diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 38767975c1..6ae781c17d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -18,9 +18,12 @@ jobs:
         distribution: temurin
 
     - name: Clone Flutter SDK
-      # TODO(#1204) reinstate shallow clone with --depth=1000 and its corresponding comment here
+      # We can't do a depth-1 clone, because we need the most recent tag
+      # so that Flutter knows its version and sees the constraint in our
+      # pubspec is satisfied.  It's uncommon for flutter/flutter to go
+      # more than 100 commits between tags.  Fetch 1000 for good measure.
       run: |
-        git clone -b main https://github.com/flutter/flutter ~/flutter
+        git clone --depth=1000 -b main https://github.com/flutter/flutter ~/flutter
         TZ=UTC git --git-dir ~/flutter/.git log -1 --format='%h | %ci | %s' --date=iso8601-local
         echo ~/flutter/bin >> "$GITHUB_PATH"
 
diff --git a/.github/workflows/update-translations.yml b/.github/workflows/update-translations.yml
index b0e934e287..1fc63e27c2 100644
--- a/.github/workflows/update-translations.yml
+++ b/.github/workflows/update-translations.yml
@@ -1,22 +1,56 @@
 name: Update translations from Weblate
+permissions:
+  contents: write
+  pull-requests: write
 on:
+  pull_request:
   schedule:
     - cron: "0 10 * * 1"
   workflow_dispatch:
+
 jobs:
   update-translations:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
       - name: Fetch and merge from Weblate
         # The commit message is generated in Weblate; see https://hosted.weblate.org/addon/17163/
         run: |
+          git checkout -b main
+          git log --oneline --graph --all -n5
           git remote add weblate https://hosted.weblate.org/git/zulip/zulip-flutter/
           git fetch weblate
-          git merge --ff-only weblate/main
+          GIT_COMMITTER_NAME="Hosted Weblate" GIT_COMMITTER_EMAIL="hosted@weblate.org" \
+            git cherry-pick weblate/main ^HEAD
+
+      - name: Clone Flutter SDK
+        # TODO(#1204) reinstate shallow clone with --depth=1000 and its corresponding comment here
+        run: |
+          git clone -b main https://github.com/flutter/flutter ~/flutter
+          TZ=UTC git --git-dir ~/flutter/.git log -1 --format='%h | %ci | %s' --date=iso8601-local
+          echo ~/flutter/bin >> "$GITHUB_PATH"
+
+          # The Flutter tool assumes the tip of tree is "origin/master"
+          # (or "upstream/master"):
+          #   https://github.com/flutter/flutter/issues/160626
+          # TODO(upstream): make workaround unneeded
+          git --git-dir ~/flutter/.git update-ref refs/remotes/origin/master origin/main
+
+      - name: Update generated code
+        run: |
+          mkdir -p build
+          tools/check l10n --fix
+          git add lib/generated/l10n/
+          GIT_COMMITTER_NAME="Hosted Weblate" GIT_COMMITTER_EMAIL="hosted@weblate.org" \
+            git commit --amend -C HEAD
+
       - name: Create Pull Request
         uses: peter-evans/create-pull-request@v7
         with:
           branch: update-translations/weblate
           delete-branch: true
           title: Update translations from Weblate
+          base: ${{ github.head_ref }}
diff --git a/android/app/src/main/kotlin/com/zulip/flutter/Notifications.g.kt b/android/app/src/main/kotlin/com/zulip/flutter/Notifications.g.kt
index 2fb36634e6..2070473b96 100644
--- a/android/app/src/main/kotlin/com/zulip/flutter/Notifications.g.kt
+++ b/android/app/src/main/kotlin/com/zulip/flutter/Notifications.g.kt
@@ -1,4 +1,4 @@
-// Autogenerated from Pigeon (v20.0.2), do not edit directly.
+// Autogenerated from Pigeon (v22.7.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 @file:Suppress("UNCHECKED_CAST", "ArrayInDataClass")
 
@@ -7,7 +7,9 @@ package com.zulip.flutter
 import android.util.Log
 import io.flutter.plugin.common.BasicMessageChannel
 import io.flutter.plugin.common.BinaryMessenger
+import io.flutter.plugin.common.EventChannel
 import io.flutter.plugin.common.MessageCodec
+import io.flutter.plugin.common.StandardMethodCodec
 import io.flutter.plugin.common.StandardMessageCodec
 import java.io.ByteArrayOutputStream
 import java.nio.ByteBuffer
@@ -64,17 +66,16 @@ data class NotificationChannel (
   val lightsEnabled: Boolean? = null,
   val soundUrl: String? = null,
   val vibrationPattern: LongArray? = null
-
-) {
+)
+ {
   companion object {
-    @Suppress("LocalVariableName")
-    fun fromList(__pigeon_list: List<Any?>): NotificationChannel {
-      val id = __pigeon_list[0] as String
-      val importance = __pigeon_list[1].let { num -> if (num is Int) num.toLong() else num as Long }
-      val name = __pigeon_list[2] as String?
-      val lightsEnabled = __pigeon_list[3] as Boolean?
-      val soundUrl = __pigeon_list[4] as String?
-      val vibrationPattern = __pigeon_list[5] as LongArray?
+    fun fromList(pigeonVar_list: List<Any?>): NotificationChannel {
+      val id = pigeonVar_list[0] as String
+      val importance = pigeonVar_list[1] as Long
+      val name = pigeonVar_list[2] as String?
+      val lightsEnabled = pigeonVar_list[3] as Boolean?
+      val soundUrl = pigeonVar_list[4] as String?
+      val vibrationPattern = pigeonVar_list[5] as LongArray?
       return NotificationChannel(id, importance, name, lightsEnabled, soundUrl, vibrationPattern)
     }
   }
@@ -104,14 +105,13 @@ data class AndroidIntent (
   val dataUrl: String,
   /** A combination of flags from [IntentFlag]. */
   val flags: Long
-
-) {
+)
+ {
   companion object {
-    @Suppress("LocalVariableName")
-    fun fromList(__pigeon_list: List<Any?>): AndroidIntent {
-      val action = __pigeon_list[0] as String
-      val dataUrl = __pigeon_list[1] as String
-      val flags = __pigeon_list[2].let { num -> if (num is Int) num.toLong() else num as Long }
+    fun fromList(pigeonVar_list: List<Any?>): AndroidIntent {
+      val action = pigeonVar_list[0] as String
+      val dataUrl = pigeonVar_list[1] as String
+      val flags = pigeonVar_list[2] as Long
       return AndroidIntent(action, dataUrl, flags)
     }
   }
@@ -139,14 +139,13 @@ data class PendingIntent (
    * with `Intent`; see Android docs for `PendingIntent.getActivity`.
    */
   val flags: Long
-
-) {
+)
+ {
   companion object {
-    @Suppress("LocalVariableName")
-    fun fromList(__pigeon_list: List<Any?>): PendingIntent {
-      val requestCode = __pigeon_list[0].let { num -> if (num is Int) num.toLong() else num as Long }
-      val intent = __pigeon_list[1] as AndroidIntent
-      val flags = __pigeon_list[2].let { num -> if (num is Int) num.toLong() else num as Long }
+    fun fromList(pigeonVar_list: List<Any?>): PendingIntent {
+      val requestCode = pigeonVar_list[0] as Long
+      val intent = pigeonVar_list[1] as AndroidIntent
+      val flags = pigeonVar_list[2] as Long
       return PendingIntent(requestCode, intent, flags)
     }
   }
@@ -168,12 +167,11 @@ data class PendingIntent (
  */
 data class InboxStyle (
   val summaryText: String
-
-) {
+)
+ {
   companion object {
-    @Suppress("LocalVariableName")
-    fun fromList(__pigeon_list: List<Any?>): InboxStyle {
-      val summaryText = __pigeon_list[0] as String
+    fun fromList(pigeonVar_list: List<Any?>): InboxStyle {
+      val summaryText = pigeonVar_list[0] as String
       return InboxStyle(summaryText)
     }
   }
@@ -205,14 +203,13 @@ data class Person (
   val iconBitmap: ByteArray? = null,
   val key: String,
   val name: String
-
-) {
+)
+ {
   companion object {
-    @Suppress("LocalVariableName")
-    fun fromList(__pigeon_list: List<Any?>): Person {
-      val iconBitmap = __pigeon_list[0] as ByteArray?
-      val key = __pigeon_list[1] as String
-      val name = __pigeon_list[2] as String
+    fun fromList(pigeonVar_list: List<Any?>): Person {
+      val iconBitmap = pigeonVar_list[0] as ByteArray?
+      val key = pigeonVar_list[1] as String
+      val name = pigeonVar_list[2] as String
       return Person(iconBitmap, key, name)
     }
   }
@@ -236,14 +233,13 @@ data class MessagingStyleMessage (
   val text: String,
   val timestampMs: Long,
   val person: Person
-
-) {
+)
+ {
   companion object {
-    @Suppress("LocalVariableName")
-    fun fromList(__pigeon_list: List<Any?>): MessagingStyleMessage {
-      val text = __pigeon_list[0] as String
-      val timestampMs = __pigeon_list[1].let { num -> if (num is Int) num.toLong() else num as Long }
-      val person = __pigeon_list[2] as Person
+    fun fromList(pigeonVar_list: List<Any?>): MessagingStyleMessage {
+      val text = pigeonVar_list[0] as String
+      val timestampMs = pigeonVar_list[1] as Long
+      val person = pigeonVar_list[2] as Person
       return MessagingStyleMessage(text, timestampMs, person)
     }
   }
@@ -266,17 +262,16 @@ data class MessagingStyleMessage (
 data class MessagingStyle (
   val user: Person,
   val conversationTitle: String? = null,
-  val messages: List<MessagingStyleMessage?>,
+  val messages: List<MessagingStyleMessage>,
   val isGroupConversation: Boolean
-
-) {
+)
+ {
   companion object {
-    @Suppress("LocalVariableName")
-    fun fromList(__pigeon_list: List<Any?>): MessagingStyle {
-      val user = __pigeon_list[0] as Person
-      val conversationTitle = __pigeon_list[1] as String?
-      val messages = __pigeon_list[2] as List<MessagingStyleMessage?>
-      val isGroupConversation = __pigeon_list[3] as Boolean
+    fun fromList(pigeonVar_list: List<Any?>): MessagingStyle {
+      val user = pigeonVar_list[0] as Person
+      val conversationTitle = pigeonVar_list[1] as String?
+      val messages = pigeonVar_list[2] as List<MessagingStyleMessage>
+      val isGroupConversation = pigeonVar_list[3] as Boolean
       return MessagingStyle(user, conversationTitle, messages, isGroupConversation)
     }
   }
@@ -299,14 +294,13 @@ data class MessagingStyle (
  */
 data class Notification (
   val group: String,
-  val extras: Map<String?, String?>
-
-) {
+  val extras: Map<String, String>
+)
+ {
   companion object {
-    @Suppress("LocalVariableName")
-    fun fromList(__pigeon_list: List<Any?>): Notification {
-      val group = __pigeon_list[0] as String
-      val extras = __pigeon_list[1] as Map<String?, String?>
+    fun fromList(pigeonVar_list: List<Any?>): Notification {
+      val group = pigeonVar_list[0] as String
+      val extras = pigeonVar_list[1] as Map<String, String>
       return Notification(group, extras)
     }
   }
@@ -329,14 +323,13 @@ data class StatusBarNotification (
   val id: Long,
   val tag: String,
   val notification: Notification
-
-) {
+)
+ {
   companion object {
-    @Suppress("LocalVariableName")
-    fun fromList(__pigeon_list: List<Any?>): StatusBarNotification {
-      val id = __pigeon_list[0].let { num -> if (num is Int) num.toLong() else num as Long }
-      val tag = __pigeon_list[1] as String
-      val notification = __pigeon_list[2] as Notification
+    fun fromList(pigeonVar_list: List<Any?>): StatusBarNotification {
+      val id = pigeonVar_list[0] as Long
+      val tag = pigeonVar_list[1] as String
+      val notification = pigeonVar_list[2] as Notification
       return StatusBarNotification(id, tag, notification)
     }
   }
@@ -370,14 +363,13 @@ data class StoredNotificationSound (
   val isOwned: Boolean,
   /** A `content://…` URL pointing to the sound file. */
   val contentUrl: String
-
-) {
+)
+ {
   companion object {
-    @Suppress("LocalVariableName")
-    fun fromList(__pigeon_list: List<Any?>): StoredNotificationSound {
-      val fileName = __pigeon_list[0] as String
-      val isOwned = __pigeon_list[1] as Boolean
-      val contentUrl = __pigeon_list[2] as String
+    fun fromList(pigeonVar_list: List<Any?>): StoredNotificationSound {
+      val fileName = pigeonVar_list[0] as String
+      val isOwned = pigeonVar_list[1] as Boolean
+      val contentUrl = pigeonVar_list[2] as String
       return StoredNotificationSound(fileName, isOwned, contentUrl)
     }
   }
@@ -389,7 +381,7 @@ data class StoredNotificationSound (
     )
   }
 }
-private object NotificationsPigeonCodec : StandardMessageCodec() {
+private open class NotificationsPigeonCodec : StandardMessageCodec() {
   override fun readValueOfType(type: Byte, buffer: ByteBuffer): Any? {
     return when (type) {
       129.toByte() -> {
@@ -561,7 +553,7 @@ interface AndroidNotificationHostApi {
    *   https://developer.android.com/reference/kotlin/android/app/NotificationManager.html#notify
    *   https://developer.android.com/reference/androidx/core/app/NotificationCompat.Builder
    */
-  fun notify(tag: String?, id: Long, autoCancel: Boolean?, channelId: String, color: Long?, contentIntent: PendingIntent?, contentText: String?, contentTitle: String?, extras: Map<String?, String?>?, groupKey: String?, inboxStyle: InboxStyle?, isGroupSummary: Boolean?, messagingStyle: MessagingStyle?, number: Long?, smallIconResourceName: String?)
+  fun notify(tag: String?, id: Long, autoCancel: Boolean?, channelId: String, color: Long?, contentIntent: PendingIntent?, contentText: String?, contentTitle: String?, extras: Map<String, String>?, groupKey: String?, inboxStyle: InboxStyle?, isGroupSummary: Boolean?, messagingStyle: MessagingStyle?, number: Long?, smallIconResourceName: String?)
   /**
    * Wraps `androidx.core.app.NotificationManagerCompat.getActiveNotifications`,
    * combined with `androidx.core.app.NotificationCompat.MessagingStyle.extractMessagingStyleFromNotification`.
@@ -597,7 +589,7 @@ interface AndroidNotificationHostApi {
   companion object {
     /** The codec used by AndroidNotificationHostApi. */
     val codec: MessageCodec<Any?> by lazy {
-      NotificationsPigeonCodec
+      NotificationsPigeonCodec()
     }
     /** Sets up an instance of `AndroidNotificationHostApi` to handle messages through the `binaryMessenger`. */
     @JvmOverloads
@@ -693,19 +685,19 @@ interface AndroidNotificationHostApi {
           channel.setMessageHandler { message, reply ->
             val args = message as List<Any?>
             val tagArg = args[0] as String?
-            val idArg = args[1].let { num -> if (num is Int) num.toLong() else num as Long }
+            val idArg = args[1] as Long
             val autoCancelArg = args[2] as Boolean?
             val channelIdArg = args[3] as String
-            val colorArg = args[4].let { num -> if (num is Int) num.toLong() else num as Long? }
+            val colorArg = args[4] as Long?
             val contentIntentArg = args[5] as PendingIntent?
             val contentTextArg = args[6] as String?
             val contentTitleArg = args[7] as String?
-            val extrasArg = args[8] as Map<String?, String?>?
+            val extrasArg = args[8] as Map<String, String>?
             val groupKeyArg = args[9] as String?
             val inboxStyleArg = args[10] as InboxStyle?
             val isGroupSummaryArg = args[11] as Boolean?
             val messagingStyleArg = args[12] as MessagingStyle?
-            val numberArg = args[13].let { num -> if (num is Int) num.toLong() else num as Long? }
+            val numberArg = args[13] as Long?
             val smallIconResourceNameArg = args[14] as String?
             val wrapped: List<Any?> = try {
               api.notify(tagArg, idArg, autoCancelArg, channelIdArg, colorArg, contentIntentArg, contentTextArg, contentTitleArg, extrasArg, groupKeyArg, inboxStyleArg, isGroupSummaryArg, messagingStyleArg, numberArg, smallIconResourceNameArg)
@@ -759,7 +751,7 @@ interface AndroidNotificationHostApi {
           channel.setMessageHandler { message, reply ->
             val args = message as List<Any?>
             val tagArg = args[0] as String?
-            val idArg = args[1].let { num -> if (num is Int) num.toLong() else num as Long }
+            val idArg = args[1] as Long
             val wrapped: List<Any?> = try {
               api.cancel(tagArg, idArg)
               listOf(null)
diff --git a/android/app/src/main/kotlin/com/zulip/flutter/ZulipPlugin.kt b/android/app/src/main/kotlin/com/zulip/flutter/ZulipPlugin.kt
index bae5ad43ab..eb332d786f 100644
--- a/android/app/src/main/kotlin/com/zulip/flutter/ZulipPlugin.kt
+++ b/android/app/src/main/kotlin/com/zulip/flutter/ZulipPlugin.kt
@@ -183,7 +183,7 @@ private class AndroidNotificationHost(val context: Context)
         contentIntent: PendingIntent?,
         contentText: String?,
         contentTitle: String?,
-        extras: Map<String?, String?>?,
+        extras: Map<String, String>?,
         groupKey: String?,
         inboxStyle: InboxStyle?,
         isGroupSummary: Boolean?,
@@ -221,13 +221,13 @@ private class AndroidNotificationHost(val context: Context)
                 val style = NotificationCompat.MessagingStyle(toAndroidPerson(messagingStyle.user))
                     .setConversationTitle(messagingStyle.conversationTitle)
                     .setGroupConversation(messagingStyle.isGroupConversation)
-                messagingStyle.messages.forEach { it?.let {
+                messagingStyle.messages.forEach {
                     style.addMessage(NotificationCompat.MessagingStyle.Message(
                         it.text,
                         it.timestampMs,
                         toAndroidPerson(it.person),
                     ))
-                } }
+                }
                 setStyle(style)
             }
             number?.let { setNumber(it.toInt()) }
@@ -268,8 +268,11 @@ private class AndroidNotificationHost(val context: Context)
                 Notification(
                     it.notification.group,
                     desiredExtras
-                        .associateWith { key -> it.notification.extras.getString(key) }
-                        .filter { entry -> entry.value != null }
+                        .mapNotNull { key ->
+                            it.notification.extras.getString(key)?.let { value ->
+                                key to value
+                            } }
+                        .toMap()
                 ),
             )
         }
diff --git a/android/gradle.properties b/android/gradle.properties
index 0a5710a599..b0202e3120 100644
--- a/android/gradle.properties
+++ b/android/gradle.properties
@@ -1,4 +1,4 @@
-org.gradle.jvmargs=-Xmx1536M
+org.gradle.jvmargs=-Xmx4G
 android.useAndroidX=true
 android.enableJetifier=true
 
diff --git a/assets/icons/ZulipIcons.ttf b/assets/icons/ZulipIcons.ttf
index 57a301f2e8..0be670d5cb 100644
Binary files a/assets/icons/ZulipIcons.ttf and b/assets/icons/ZulipIcons.ttf differ
diff --git a/assets/icons/check.svg b/assets/icons/check.svg
new file mode 100644
index 0000000000..26332a3599
--- /dev/null
+++ b/assets/icons/check.svg
@@ -0,0 +1,3 @@
+<svg width="24" height="25" viewBox="0 0 24 25" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path fill-rule="evenodd" clip-rule="evenodd" d="M20.7071 5.79289C21.0976 6.18342 21.0976 6.81658 20.7071 7.20711L9.70711 18.2071C9.31658 18.5976 8.68342 18.5976 8.29289 18.2071L3.29289 13.2071C2.90237 12.8166 2.90237 12.1834 3.29289 11.7929C3.68342 11.4024 4.31658 11.4024 4.70711 11.7929L9 16.0858L19.2929 5.79289C19.6834 5.40237 20.3166 5.40237 20.7071 5.79289Z" fill="black"/>
+</svg>
diff --git a/assets/icons/check_remove.svg b/assets/icons/check_remove.svg
new file mode 100644
index 0000000000..cc5939b04d
--- /dev/null
+++ b/assets/icons/check_remove.svg
@@ -0,0 +1,4 @@
+<svg width="24" height="25" viewBox="0 0 24 25" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path d="M19.2058 4.20528L8.20577 15.2053C7.81622 15.5948 7.18464 15.5948 6.79509 15.2053L1.79509 10.2053C1.40554 9.81573 1.40554 9.18415 1.79509 8.7946C2.18464 8.40505 2.81622 8.40505 3.20577 8.7946L7.50043 13.0893L17.7951 2.7946C18.1846 2.40505 18.8162 2.40505 19.2058 2.7946C19.5953 3.18415 19.5953 3.81573 19.2058 4.20528Z" fill="black"/>
+<path d="M12.7045 13.2045C13.1438 12.7652 13.8562 12.7652 14.2955 13.2045L17.25 16.159L20.2045 13.2045C20.6438 12.7652 21.3562 12.7652 21.7955 13.2045C22.2348 13.6438 22.2348 14.3562 21.7955 14.7955L18.841 17.75L21.7955 20.7045C22.2348 21.1438 22.2348 21.8562 21.7955 22.2955C21.3562 22.7348 20.6438 22.7348 20.2045 22.2955L17.25 19.341L14.2955 22.2955C13.8562 22.7348 13.1438 22.7348 12.7045 22.2955C12.2652 21.8562 12.2652 21.1438 12.7045 20.7045L15.659 17.75L12.7045 14.7955C12.2652 14.3562 12.2652 13.6438 12.7045 13.2045Z" fill="black"/>
+</svg>
diff --git a/assets/icons/three_person.svg b/assets/icons/three_person.svg
new file mode 100644
index 0000000000..294155cf5a
--- /dev/null
+++ b/assets/icons/three_person.svg
@@ -0,0 +1,8 @@
+<svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path fill-rule="evenodd" clip-rule="evenodd" d="M11.2788 14.675C11.9843 13.8766 12.9697 13.3999 14.0276 13.3999H19.6828C20.7407 13.3999 21.7261 13.8766 22.4316 14.675C23.1336 15.4694 23.5105 16.5232 23.5105 17.5999V19.1999C23.5105 19.7522 23.0628 20.1999 22.5105 20.1999C21.9582 20.1999 21.5105 19.7522 21.5105 19.1999V17.5999C21.5105 16.9792 21.2915 16.4051 20.9329 15.9993C20.5779 15.5975 20.1248 15.3999 19.6828 15.3999H14.0276C13.5856 15.3999 13.1325 15.5975 12.7775 15.9993C12.4189 16.4051 12.2 16.9792 12.2 17.5999V19.1999C12.2 19.7522 11.7522 20.1999 11.2 20.1999C10.6477 20.1999 10.2 19.7522 10.2 19.1999V17.5999C10.2 16.5232 10.5768 15.4694 11.2788 14.675Z" fill="black"/>
+<path fill-rule="evenodd" clip-rule="evenodd" d="M16.7999 5.8C15.5849 5.8 14.5999 6.78497 14.5999 8C14.5999 9.21503 15.5849 10.2 16.7999 10.2C18.0149 10.2 18.9999 9.21503 18.9999 8C18.9999 6.78497 18.0149 5.8 16.7999 5.8ZM12.5999 8C12.5999 5.6804 14.4803 3.8 16.7999 3.8C19.1195 3.8 20.9999 5.6804 20.9999 8C20.9999 10.3196 19.1195 12.2 16.7999 12.2C14.4803 12.2 12.5999 10.3196 12.5999 8Z" fill="black"/>
+<path fill-rule="evenodd" clip-rule="evenodd" d="M5.16832 14.2537C5.03025 13.7189 4.48482 13.3973 3.95007 13.5354C3.04904 13.7681 2.25078 14.2934 1.68064 15.0288C1.1105 15.7643 0.800768 16.6683 0.800074 17.5989L0.800073 19.1997C0.800073 19.7519 1.24779 20.1997 1.80007 20.1997C2.35236 20.1997 2.80007 19.7519 2.80007 19.1997V17.6001C2.8005 17.1128 2.96274 16.6394 3.26132 16.2542C3.55997 15.8689 3.9781 15.5938 4.45007 15.4719C4.98482 15.3338 5.30639 14.7884 5.16832 14.2537Z" fill="black"/>
+<path fill-rule="evenodd" clip-rule="evenodd" d="M7.36865 4.65567C7.23166 4.12065 6.68689 3.79797 6.15186 3.93496C5.24843 4.16628 4.44767 4.6917 3.87584 5.42839C3.30401 6.16508 2.99363 7.07113 2.99363 8.00371C2.99363 8.93629 3.30401 9.84235 3.87584 10.579C4.44767 11.3157 5.24843 11.8411 6.15186 12.0725C6.68689 12.2094 7.23166 11.8868 7.36865 11.3518C7.50564 10.8167 7.18297 10.2719 6.64794 10.135C6.17471 10.0138 5.75527 9.73858 5.45574 9.35269C5.15621 8.9668 4.99363 8.4922 4.99363 8.00371C4.99363 7.51522 5.15621 7.04062 5.45574 6.65473C5.75527 6.26885 6.17471 5.99363 6.64794 5.87246C7.18297 5.73547 7.50564 5.1907 7.36865 4.65567Z" fill="black"/>
+<path fill-rule="evenodd" clip-rule="evenodd" d="M9.96837 14.2537C9.8303 13.7189 9.28487 13.3973 8.75012 13.5354C7.84909 13.7681 7.05083 14.2934 6.48069 15.0288C5.91055 15.7643 5.60082 16.6683 5.60012 17.5989L5.60012 19.1997C5.60012 19.7519 6.04784 20.1997 6.60012 20.1997C7.15241 20.1997 7.60012 19.7519 7.60012 19.1997V17.6001C7.60055 17.1128 7.76279 16.6394 8.06137 16.2542C8.36002 15.8689 8.77815 15.5938 9.25012 15.4719C9.78487 15.3338 10.1064 14.7884 9.96837 14.2537Z" fill="black"/>
+<path fill-rule="evenodd" clip-rule="evenodd" d="M12.1687 4.65577C12.0317 4.12074 11.4869 3.79807 10.9519 3.93506C10.0485 4.16637 9.24772 4.69179 8.67589 5.42848C8.10406 6.16517 7.79368 7.07123 7.79368 8.00381C7.79368 8.93639 8.10406 9.84244 8.67589 10.5791C9.24772 11.3158 10.0485 11.8412 10.9519 12.0726C11.4869 12.2095 12.0317 11.8869 12.1687 11.3518C12.3057 10.8168 11.983 10.272 11.448 10.1351C10.9748 10.0139 10.5553 9.73867 10.2558 9.35279C9.95626 8.9669 9.79368 8.4923 9.79368 8.00381C9.79368 7.51532 9.95626 7.04071 10.2558 6.65483C10.5553 6.26894 10.9748 5.99372 11.448 5.87256C11.983 5.73557 12.3057 5.1908 12.1687 4.65577Z" fill="black"/>
+</svg>
diff --git a/assets/l10n/app_ar.arb b/assets/l10n/app_ar.arb
index 0967ef424b..5ca1208723 100644
--- a/assets/l10n/app_ar.arb
+++ b/assets/l10n/app_ar.arb
@@ -1 +1,11 @@
-{}
+{
+  "wildcardMentionAll": "الجميع",
+  "wildcardMentionEveryone": "الكل",
+  "wildcardMentionChannel": "القناة",
+  "wildcardMentionStream": "الدفق",
+  "wildcardMentionTopic": "الموضوع",
+  "wildcardMentionChannelDescription": "إخطار القناة",
+  "wildcardMentionStreamDescription": "إخطار الدفق",
+  "wildcardMentionAllDmDescription": "إخطار المستلمين",
+  "wildcardMentionTopicDescription": "إخطار الموضوع"
+}
diff --git a/assets/l10n/app_en.arb b/assets/l10n/app_en.arb
index 58822303fd..0640af9ee1 100644
--- a/assets/l10n/app_en.arb
+++ b/assets/l10n/app_en.arb
@@ -56,6 +56,10 @@
   "@profileButtonSendDirectMessage": {
     "description": "Label for button in profile screen to navigate to DMs with the shown user."
   },
+  "errorCouldNotShowUserProfile": "Could not show user profile.",
+  "@errorCouldNotShowUserProfile": {
+    "description": "Message that appears on the user profile page when the profile cannot be shown."
+  },
   "permissionsNeededTitle": "Permissions needed",
   "@permissionsNeededTitle": {
     "description": "Title for dialog asking the user to grant additional permissions."
@@ -88,6 +92,22 @@
   "@actionSheetOptionUnfollowTopic":  {
     "description": "Label for unfollowing a topic on action sheet."
   },
+  "actionSheetOptionResolveTopic": "Mark as resolved",
+  "@actionSheetOptionResolveTopic": {
+    "description": "Label for the 'Mark as resolved' button on the topic action sheet."
+  },
+  "actionSheetOptionUnresolveTopic": "Mark as unresolved",
+  "@actionSheetOptionUnresolveTopic": {
+    "description": "Label for the 'Mark as unresolved' button on the topic action sheet."
+  },
+  "errorResolveTopicFailedTitle": "Failed to mark topic as resolved",
+  "@errorResolveTopicFailedTitle": {
+    "description": "Error title when marking a topic as resolved failed."
+  },
+  "errorUnresolveTopicFailedTitle": "Failed to mark topic as unresolved",
+  "@errorUnresolveTopicFailedTitle": {
+    "description": "Error title when marking a topic as unresolved failed."
+  },
   "actionSheetOptionCopyMessageText": "Copy message text",
   "@actionSheetOptionCopyMessageText":  {
     "description": "Label for copy message text button on action sheet."
@@ -151,13 +171,21 @@
       "filename": {"type": "String", "example": "file.txt"}
     }
   },
+  "filenameAndSizeInMiB": "{filename}: {size} MiB",
+  "@filenameAndSizeInMiB": {
+    "description": "The name of a file, and its size in mebibytes.",
+    "placeholders": {
+      "filename": {"type": "String", "example": "foo.txt"},
+      "size": {"type": "String", "example": "20.2"}
+    }
+  },
   "errorFilesTooLarge": "{num, plural, =1{File is} other{{num} files are}} larger than the server's limit of {maxFileUploadSizeMib} MiB and will not be uploaded:\n\n{listMessage}",
   "@errorFilesTooLarge": {
     "description": "Error message when attached files are too large in size.",
     "placeholders": {
       "num": {"type": "int", "example": "2"},
       "maxFileUploadSizeMib": {"type": "int", "example": "15"},
-      "listMessage": {"type": "String", "example": "foo.txt\nbar.txt"}
+      "listMessage": {"type": "String", "example": "foo.txt: 10.1 MiB\nbar.txt 20.2 MiB"}
     }
   },
   "errorFilesTooLargeTitle": "{num, plural, =1{File} other{Files}} too large",
@@ -230,6 +258,17 @@
       "event": {"type": "String", "example": "UpdateMessageEvent(id: 123, messageIds: [2345, 3456], newTopic: 'dinner')"}
     }
   },
+  "errorCouldNotOpenLinkTitle": "Unable to open link",
+  "@errorCouldNotOpenLinkTitle": {
+    "description": "Error title when opening a link failed."
+  },
+  "errorCouldNotOpenLink": "Link could not be opened: {url}",
+  "@errorCouldNotOpenLink": {
+    "description": "Error message when opening a link failed.",
+    "placeholders": {
+      "url": {"type":  "String", "example":  "https://chat.example.com"}
+    }
+  },
   "errorMuteTopicFailed": "Failed to mute topic",
   "@errorMuteTopicFailed": {
     "description": "Error message when muting a topic failed."
@@ -321,8 +360,8 @@
   "@composeBoxSendTooltip":  {
     "description": "Tooltip for send button in compose box."
   },
-  "composeBoxUnknownChannelName": "(unknown channel)",
-  "@composeBoxUnknownChannelName": {
+  "unknownChannelName": "(unknown channel)",
+  "@unknownChannelName": {
     "description": "Replacement name for channel when it cannot be found in the store."
   },
   "composeBoxTopicHintText": "Topic",
@@ -336,10 +375,21 @@
       "filename": {"type": "String", "example": "file.txt"}
     }
   },
+  "composeBoxLoadingMessage": "(loading message {messageId})",
+  "@composeBoxLoadingMessage": {
+    "description": "Placeholder in compose box showing the quoted message is currently loading.",
+    "placeholders": {
+      "messageId": {"type": "int", "example": "1234"}
+    }
+  },
   "unknownUserName": "(unknown user)",
   "@unknownUserName": {
     "description": "Name placeholder to use for a user when we don't know their name."
   },
+  "dmsWithYourselfPageTitle": "DMs with yourself",
+  "@dmsWithYourselfPageTitle": {
+    "description": "Message list page title for a DM group that only includes yourself."
+  },
   "messageListGroupYouAndOthers": "You and {others}",
   "@messageListGroupYouAndOthers": {
     "description": "Message list recipient header for a DM group with others.",
@@ -347,6 +397,13 @@
       "others": {"type": "String", "example": "Alice, Bob"}
     }
   },
+  "dmsWithOthersPageTitle": "DMs with {others}",
+  "@dmsWithOthersPageTitle": {
+    "description": "Message list page title for a DM group with others.",
+    "placeholders": {
+      "others": {"type": "String", "example": "Alice, Bob"}
+    }
+  },
   "messageListGroupYouWithYourself": "You with yourself",
   "@messageListGroupYouWithYourself": {
     "description": "Message list recipient header for a DM group that only includes yourself."
@@ -395,6 +452,14 @@
   "@lightboxCopyLinkTooltip": {
     "description": "Tooltip in lightbox for the copy link action."
   },
+  "lightboxVideoCurrentPosition": "Current position",
+  "@lightboxVideoCurrentPosition": {
+    "description": "The current playback position of the video playing in the lightbox."
+  },
+  "lightboxVideoDuration": "Video duration",
+  "@lightboxVideoDuration": {
+    "description": "The total duration of the video playing in the lightbox."
+  },
   "loginPageTitle": "Log in",
   "@loginPageTitle": {
     "description": "Title for login page."
@@ -418,9 +483,9 @@
   "@loginAddAnAccountPageTitle": {
     "description": "Title for page to add a Zulip account."
   },
-  "loginServerUrlInputLabel": "Your Zulip server URL",
-  "@loginServerUrlInputLabel": {
-    "description": "Input label in login page for Zulip server URL entry."
+  "loginServerUrlLabel": "Your Zulip server URL",
+  "@loginServerUrlLabel": {
+    "description": "Label in login page for Zulip server URL entry."
   },
   "loginHidePassword": "Hide password",
   "@loginHidePassword": {
@@ -586,6 +651,10 @@
   "@recentDmConversationsPageTitle": {
     "description": "Title for the page with a list of DM conversations."
   },
+  "recentDmConversationsSectionHeader": "Direct messages",
+  "@recentDmConversationsSectionHeader": {
+    "description": "Heading for direct messages section on the 'Inbox' message view."
+  },
   "combinedFeedPageTitle": "Combined feed",
   "@combinedFeedPageTitle": {
     "description": "Page title for the 'Combined feed' message view."
@@ -618,10 +687,26 @@
       "numOthers": {"type": "int", "example": "4"}
     }
   },
+  "pinnedSubscriptionsLabel": "Pinned",
+  "@pinnedSubscriptionsLabel": {
+    "description": "Label for the list of pinned subscribed channels."
+  },
+  "unpinnedSubscriptionsLabel": "Unpinned",
+  "@unpinnedSubscriptionsLabel": {
+    "description": "Label for the list of unpinned subscribed channels."
+  },
+  "subscriptionListNoChannels": "No channels found",
+  "@subscriptionListNoChannels": {
+    "description": "Text to display on subscribed-channels page when there are no subscribed channels."
+  },
   "notifSelfUser": "You",
   "@notifSelfUser": {
     "description": "Display name for the user themself, to show after replying in an Android notification"
   },
+  "reactedEmojiSelfUser": "You",
+  "@reactedEmojiSelfUser": {
+    "description": "Display name for the user themself, to show on an emoji reaction added by the user."
+  },
   "onePersonTyping": "{typist} is typing…",
   "@onePersonTyping": {
     "description": "Text to display when there is one user typing.",
@@ -641,6 +726,42 @@
   "@manyPeopleTyping": {
     "description": "Text to display when there are multiple users typing."
   },
+  "wildcardMentionAll": "all",
+  "@wildcardMentionAll": {
+    "description": "Text for \"@all\" wildcard-mention autocomplete option when writing a channel or DM message."
+  },
+  "wildcardMentionEveryone": "everyone",
+  "@wildcardMentionEveryone": {
+    "description": "Text for \"@everyone\" wildcard-mention autocomplete option when writing a channel or DM message."
+  },
+  "wildcardMentionChannel": "channel",
+  "@wildcardMentionChannel": {
+    "description": "Text for \"@channel\" wildcard-mention autocomplete option when writing a channel message."
+  },
+  "wildcardMentionStream": "stream",
+  "@wildcardMentionStream": {
+    "description": "Text for \"@stream\" wildcard-mention autocomplete option when writing a channel message in older servers."
+  },
+  "wildcardMentionTopic": "topic",
+  "@wildcardMentionTopic": {
+    "description": "Text for \"@topic\" wildcard-mention autocomplete option when writing a channel message."
+  },
+  "wildcardMentionChannelDescription": "Notify channel",
+  "@wildcardMentionChannelDescription": {
+    "description": "Description for \"@all\", \"@everyone\", \"@channel\", and \"@stream\" wildcard-mention autocomplete options when writing a channel message."
+  },
+  "wildcardMentionStreamDescription": "Notify stream",
+  "@wildcardMentionStreamDescription": {
+    "description": "Description for \"@all\", \"@everyone\", and \"@stream\" wildcard-mention autocomplete options when writing a channel message in older servers."
+  },
+  "wildcardMentionAllDmDescription": "Notify recipients",
+  "@wildcardMentionAllDmDescription": {
+    "description": "Description for \"@all\" and \"@everyone\" wildcard-mention autocomplete options when writing a DM message."
+  },
+  "wildcardMentionTopicDescription": "Notify topic",
+  "@wildcardMentionTopicDescription": {
+    "description": "Description for \"@topic\" wildcard-mention autocomplete options when writing a channel message."
+  },
   "messageIsEditedLabel": "EDITED",
   "@messageIsEditedLabel": {
     "description": "Label for an edited message. (Use ALL CAPS for cased alphabets: Latin, Greek, Cyrillic, etc.)"
@@ -649,6 +770,13 @@
   "@messageIsMovedLabel": {
     "description": "Label for a moved message. (Use ALL CAPS for cased alphabets: Latin, Greek, Cyrillic, etc.)"
   },
+  "pollVoterNames": "({voterNames})",
+  "@pollVoterNames": {
+    "description": "The list of people who voted for a poll option, wrapped in parentheses.",
+    "placeholders": {
+      "voterNames": {"type":  "String", "example": "Alice, Bob, Chad"}
+    }
+  },
   "pollWidgetQuestionMissing": "No question.",
   "@pollWidgetQuestionMissing": {
     "description": "Text to display for a poll when the question is missing"
@@ -680,5 +808,21 @@
   "emojiPickerSearchEmoji": "Search emoji",
   "@emojiPickerSearchEmoji": {
     "description": "Hint text for the emoji picker search text field."
+  },
+  "noEarlierMessages": "No earlier messages",
+  "@noEarlierMessages": {
+    "description": "Text to show at the start of a message list if there are no earlier messages."
+  },
+  "scrollToBottomTooltip": "Scroll to bottom",
+  "@scrollToBottomTooltip": {
+    "description": "Tooltip for button to scroll to bottom."
+  },
+  "appVersionUnknownPlaceholder": "(…)",
+  "@appVersionUnknownPlaceholder": {
+    "description": "Placeholder to show in place of the app version when it is unknown."
+  },
+  "zulipAppTitle": "Zulip",
+  "@zulipAppTitle": {
+    "description": "The name of Zulip. This should be either 'Zulip' or a transliteration."
   }
 }
diff --git a/assets/l10n/app_nb.arb b/assets/l10n/app_nb.arb
index 0967ef424b..fb72c02a9d 100644
--- a/assets/l10n/app_nb.arb
+++ b/assets/l10n/app_nb.arb
@@ -1 +1,14 @@
-{}
+{
+  "aboutPageAppVersion": "App versjon",
+  "@aboutPageAppVersion": {
+    "description": "Label for Zulip app version in About Zulip page"
+  },
+  "aboutPageTitle": "Om Zulip",
+  "@aboutPageTitle": {
+    "description": "Title for About Zulip page."
+  },
+  "aboutPageOpenSourceLicenses": "Lisenser for åpen kildekode",
+  "@aboutPageOpenSourceLicenses": {
+    "description": "Item title in About Zulip page to navigate to Licenses page"
+  }
+}
diff --git a/assets/l10n/app_pl.arb b/assets/l10n/app_pl.arb
index ba918083d1..6821033271 100644
--- a/assets/l10n/app_pl.arb
+++ b/assets/l10n/app_pl.arb
@@ -277,10 +277,6 @@
       }
     }
   },
-  "composeBoxUnknownChannelName": "(nieznany kanał)",
-  "@composeBoxUnknownChannelName": {
-    "description": "Replacement name for channel when it cannot be found in the store."
-  },
   "composeBoxTopicHintText": "Wątek",
   "@composeBoxTopicHintText": {
     "description": "Hint text for topic input widget in compose box."
@@ -359,9 +355,9 @@
   "@loginAddAnAccountPageTitle": {
     "description": "Title for page to add a Zulip account."
   },
-  "loginServerUrlInputLabel": "URL serwera Zulip",
-  "@loginServerUrlInputLabel": {
-    "description": "Input label in login page for Zulip server URL entry."
+  "loginServerUrlLabel": "URL serwera Zulip",
+  "@loginServerUrlLabel": {
+    "description": "Label in login page for Zulip server URL entry."
   },
   "loginHidePassword": "Ukryj hasło",
   "@loginHidePassword": {
@@ -776,5 +772,171 @@
   "errorUnmuteTopicFailed": "Wznowienie bez powodzenia",
   "@errorUnmuteTopicFailed": {
     "description": "Error message when unmuting a topic failed."
+  },
+  "wildcardMentionAll": "wszyscy",
+  "@wildcardMentionAll": {
+    "description": "Text for \"@all\" wildcard-mention autocomplete option when writing a channel or DM message."
+  },
+  "wildcardMentionStream": "strumień",
+  "@wildcardMentionStream": {
+    "description": "Text for \"@stream\" wildcard-mention autocomplete option when writing a channel message in older servers."
+  },
+  "wildcardMentionEveryone": "każdy",
+  "@wildcardMentionEveryone": {
+    "description": "Text for \"@everyone\" wildcard-mention autocomplete option when writing a channel or DM message."
+  },
+  "wildcardMentionChannel": "kanał",
+  "@wildcardMentionChannel": {
+    "description": "Text for \"@channel\" wildcard-mention autocomplete option when writing a channel message."
+  },
+  "wildcardMentionTopic": "wątek",
+  "@wildcardMentionTopic": {
+    "description": "Text for \"@topic\" wildcard-mention autocomplete option when writing a channel message."
+  },
+  "wildcardMentionTopicDescription": "Powiadom w wątku",
+  "@wildcardMentionTopicDescription": {
+    "description": "Description for \"@topic\" wildcard-mention autocomplete options when writing a channel message."
+  },
+  "wildcardMentionAllDmDescription": "Powiadom zainteresowanych",
+  "@wildcardMentionAllDmDescription": {
+    "description": "Description for \"@all\" and \"@everyone\" wildcard-mention autocomplete options when writing a DM message."
+  },
+  "wildcardMentionStreamDescription": "Powiadom w strumieniu",
+  "@wildcardMentionStreamDescription": {
+    "description": "Description for \"@all\", \"@everyone\", and \"@stream\" wildcard-mention autocomplete options when writing a channel message in older servers."
+  },
+  "wildcardMentionChannelDescription": "Powiadom w kanale",
+  "@wildcardMentionChannelDescription": {
+    "description": "Description for \"@all\", \"@everyone\", \"@channel\", and \"@stream\" wildcard-mention autocomplete options when writing a channel message."
+  },
+  "errorCouldNotShowUserProfile": "Nie udało się wyświetlić profilu.",
+  "@errorCouldNotShowUserProfile": {
+    "description": "Message that appears on the user profile page when the profile cannot be shown."
+  },
+  "errorCouldNotOpenLinkTitle": "Nie udało się otworzyć odnośnika",
+  "@errorCouldNotOpenLinkTitle": {
+    "description": "Error title when opening a link failed."
+  },
+  "errorCouldNotOpenLink": "Nie można otworzyć: {url}",
+  "@errorCouldNotOpenLink": {
+    "description": "Error message when opening a link failed.",
+    "placeholders": {
+      "url": {
+        "type": "String",
+        "example": "https://chat.example.com"
+      }
+    }
+  },
+  "dmsWithYourselfPageTitle": "DM do siebie",
+  "@dmsWithYourselfPageTitle": {
+    "description": "Message list page title for a DM group that only includes yourself."
+  },
+  "dmsWithOthersPageTitle": "DM z {others}",
+  "@dmsWithOthersPageTitle": {
+    "description": "Message list page title for a DM group with others.",
+    "placeholders": {
+      "others": {
+        "type": "String",
+        "example": "Alice, Bob"
+      }
+    }
+  },
+  "lightboxVideoCurrentPosition": "Obecna pozycja",
+  "@lightboxVideoCurrentPosition": {
+    "description": "The current playback position of the video playing in the lightbox."
+  },
+  "lightboxVideoDuration": "Długość wideo",
+  "@lightboxVideoDuration": {
+    "description": "The total duration of the video playing in the lightbox."
+  },
+  "recentDmConversationsSectionHeader": "Wiadomości bezpośrednie",
+  "@recentDmConversationsSectionHeader": {
+    "description": "Heading for direct messages section on the 'Inbox' message view."
+  },
+  "reactedEmojiSelfUser": "Ty",
+  "@reactedEmojiSelfUser": {
+    "description": "Display name for the user themself, to show on an emoji reaction added by the user."
+  },
+  "pollVoterNames": "({voterNames})",
+  "@pollVoterNames": {
+    "description": "The list of people who voted for a poll option, wrapped in parentheses.",
+    "placeholders": {
+      "voterNames": {
+        "type": "String",
+        "example": "Alice, Bob, Chad"
+      }
+    }
+  },
+  "noEarlierMessages": "Brak historii",
+  "@noEarlierMessages": {
+    "description": "Text to show at the start of a message list if there are no earlier messages."
+  },
+  "scrollToBottomTooltip": "Przewiń do dołu",
+  "@scrollToBottomTooltip": {
+    "description": "Tooltip for button to scroll to bottom."
+  },
+  "composeBoxLoadingMessage": "(ładowanie wiadomości {messageId})",
+  "@composeBoxLoadingMessage": {
+    "description": "Placeholder in compose box showing the quoted message is currently loading.",
+    "placeholders": {
+      "messageId": {
+        "type": "int",
+        "example": "1234"
+      }
+    }
+  },
+  "pinnedSubscriptionsLabel": "Przypięte",
+  "@pinnedSubscriptionsLabel": {
+    "description": "Label for the list of pinned subscribed channels."
+  },
+  "subscriptionListNoChannels": "Nie odnaleziono kanałów",
+  "@subscriptionListNoChannels": {
+    "description": "Text to display on subscribed-channels page when there are no subscribed channels."
+  },
+  "unknownChannelName": "(nieznany kanał)",
+  "@unknownChannelName": {
+    "description": "Replacement name for channel when it cannot be found in the store."
+  },
+  "unpinnedSubscriptionsLabel": "Odpięte",
+  "@unpinnedSubscriptionsLabel": {
+    "description": "Label for the list of unpinned subscribed channels."
+  },
+  "actionSheetOptionResolveTopic": "Oznacz jako rozwiązany",
+  "@actionSheetOptionResolveTopic": {
+    "description": "Label for the 'Mark as resolved' button on the topic action sheet."
+  },
+  "actionSheetOptionUnresolveTopic": "Oznacz brak rozwiązania",
+  "@actionSheetOptionUnresolveTopic": {
+    "description": "Label for the 'Mark as unresolved' button on the topic action sheet."
+  },
+  "errorResolveTopicFailedTitle": "Nie udało się oznaczyć jako rozwiązany",
+  "@errorResolveTopicFailedTitle": {
+    "description": "Error title when marking a topic as resolved failed."
+  },
+  "errorUnresolveTopicFailedTitle": "Nie udało się oznaczyć brak rozwiązania",
+  "@errorUnresolveTopicFailedTitle": {
+    "description": "Error title when marking a topic as unresolved failed."
+  },
+  "appVersionUnknownPlaceholder": "(…)",
+  "@appVersionUnknownPlaceholder": {
+    "description": "Placeholder to show in place of the app version when it is unknown."
+  },
+  "zulipAppTitle": "Zulip",
+  "@zulipAppTitle": {
+    "description": "The name of Zulip. This should be either 'Zulip' or a transliteration."
+  },
+  "filenameAndSizeInMiB": "{filename}: {size} MiB",
+  "@filenameAndSizeInMiB": {
+    "description": "The name of a file, and its size in mebibytes.",
+    "placeholders": {
+      "filename": {
+        "type": "String",
+        "example": "foo.txt"
+      },
+      "size": {
+        "type": "String",
+        "example": "20.2"
+      }
+    }
   }
 }
diff --git a/assets/l10n/app_ru.arb b/assets/l10n/app_ru.arb
index fc7e7c964d..ef38533bb2 100644
--- a/assets/l10n/app_ru.arb
+++ b/assets/l10n/app_ru.arb
@@ -207,9 +207,9 @@
   "@loginAddAnAccountPageTitle": {
     "description": "Title for page to add a Zulip account."
   },
-  "loginServerUrlInputLabel": "URL вашего сервера Zulip",
-  "@loginServerUrlInputLabel": {
-    "description": "Input label in login page for Zulip server URL entry."
+  "loginServerUrlLabel": "URL вашего сервера Zulip",
+  "@loginServerUrlLabel": {
+    "description": "Label in login page for Zulip server URL entry."
   },
   "loginHidePassword": "Скрыть пароль",
   "@loginHidePassword": {
@@ -571,10 +571,6 @@
   "@errorFollowTopicFailed": {
     "description": "Error message when following a topic failed."
   },
-  "composeBoxUnknownChannelName": "(неизвестный канал)",
-  "@composeBoxUnknownChannelName": {
-    "description": "Replacement name for channel when it cannot be found in the store."
-  },
   "dialogContinue": "Продолжить",
   "@dialogContinue": {
     "description": "Button label in dialogs to proceed."
diff --git a/assets/l10n/app_sk.arb b/assets/l10n/app_sk.arb
index 4ad83e6790..087f459697 100644
--- a/assets/l10n/app_sk.arb
+++ b/assets/l10n/app_sk.arb
@@ -69,9 +69,9 @@
       }
     }
   },
-  "loginServerUrlInputLabel": "Adresa vášho Zulip servera",
-  "@loginServerUrlInputLabel": {
-    "description": "Input label in login page for Zulip server URL entry."
+  "loginServerUrlLabel": "Adresa vášho Zulip servera",
+  "@loginServerUrlLabel": {
+    "description": "Label in login page for Zulip server URL entry."
   },
   "errorMessageNotSent": "Správa nebola odoslaná",
   "@errorMessageNotSent": {
diff --git a/docs/changelog.md b/docs/changelog.md
index 024ab93cdb..e9e4caadd5 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -3,6 +3,43 @@
 ## Unreleased
 
 
+## 0.0.26 (2025-02-07)
+
+### Highlights for users
+
+* Resolve or unresolve a topic, from the menu after you
+  press and hold the topic. (#744)
+* Autocomplete now offers `@all`, `@topic`, and other
+  wildcards. (#234)
+* Channel names starting with emoji go at the start of the
+  list. (#1202)
+* Too many other improvements and fixes to describe them all here.
+
+
+### Highlights for developers
+
+* Resolved: #1205, #1289, #942, #1238, #1202, #1219, #1204, #1171,
+  PR #1296, #234, #1207, #1330, #1309, #725, #744
+
+
+## 0.0.25 (2025-01-13)
+
+### Highlights for users
+
+* The combined feed is now conveniently accessible from the app's main
+  navigation bar. (#1164)
+* Messages with @-topic mentions now show them properly. (#892)
+* The lightbox now shows the sender's avatar. (#41)
+* The About Zulip screen is now available from the main menu. (#1128)
+* Too many other improvements and fixes to describe them all here.
+
+
+### Highlights for developers
+
+* Resolved in main: #892, #1177, #1164, #1177, #1128, #1189, #1116,
+  #739, #41
+
+
 ## 0.0.24 (2024-12-11)
 
 This is a preview beta, including some experimental changes
diff --git a/docs/release.md b/docs/release.md
index cbf0020223..7895ba50b0 100644
--- a/docs/release.md
+++ b/docs/release.md
@@ -6,6 +6,9 @@
   Flutter and packages dependencies, do that first.
   For details of how, see our README.
 
+* Update translations from Weblate.
+  See `git log --stat --grep eblate` for previous examples.
+
 * Write an entry in `docs/changelog.md`, under "Unreleased".
   Commit that change.
 
diff --git a/docs/setup.md b/docs/setup.md
index 6a83cfa55c..03ecc87996 100644
--- a/docs/setup.md
+++ b/docs/setup.md
@@ -179,3 +179,37 @@ For the original reports and debugging of this issue, see
 chat threads
 [here](https://chat.zulip.org/#narrow/stream/243-mobile-team/topic/flutter.20json_annotation.20unexpected.20behavior/near/1824410)
 and [here](https://chat.zulip.org/#narrow/stream/516-mobile-dev-help/topic/generated.20plugin.20files.20changed/near/1944826).
+
+
+<div id="libdrm" />
+
+### Lack of libdrm on Linux target
+
+This item applies only when building the app to run as a Linux desktop
+app.  (This is an unsupported configuration which is sometimes
+convenient in development.)  It does not affect using Linux for a
+development environment when building or running Zulip as an Android
+app.
+
+When building or running as a Linux desktop app, you may see an error
+about `/usr/include/libdrm`, like this:
+```
+$ flutter run -d linux
+Launching lib/main.dart on Linux in debug mode...
+CMake Error in CMakeLists.txt:
+  Imported target "PkgConfig::GTK" includes non-existent path
+
+    "/usr/include/libdrm"
+
+  in its INTERFACE_INCLUDE_DIRECTORIES.  Possible reasons include:
+…
+```
+
+This means you need to install the header files for "DRM", part of the
+Linux graphics infrastructure.
+
+To resolve the issue, install the appropriate package from your OS
+distribution.  For example, on Debian or Ubuntu:
+```
+$ sudo apt install libdrm-dev
+```
diff --git a/ios/Podfile.lock b/ios/Podfile.lock
index a8e8b195a3..27e8691603 100644
--- a/ios/Podfile.lock
+++ b/ios/Podfile.lock
@@ -37,31 +37,31 @@ PODS:
   - file_picker (0.0.1):
     - DKImagePickerController/PhotoGallery
     - Flutter
-  - Firebase/CoreOnly (11.4.0):
-    - FirebaseCore (= 11.4.0)
-  - Firebase/Messaging (11.4.0):
+  - Firebase/CoreOnly (11.6.0):
+    - FirebaseCore (~> 11.6.0)
+  - Firebase/Messaging (11.6.0):
     - Firebase/CoreOnly
-    - FirebaseMessaging (~> 11.4.0)
-  - firebase_core (3.9.0):
-    - Firebase/CoreOnly (= 11.4.0)
+    - FirebaseMessaging (~> 11.6.0)
+  - firebase_core (3.10.0):
+    - Firebase/CoreOnly (= 11.6.0)
     - Flutter
-  - firebase_messaging (15.1.6):
-    - Firebase/Messaging (= 11.4.0)
+  - firebase_messaging (15.2.0):
+    - Firebase/Messaging (= 11.6.0)
     - firebase_core
     - Flutter
-  - FirebaseCore (11.4.0):
-    - FirebaseCoreInternal (~> 11.0)
+  - FirebaseCore (11.6.0):
+    - FirebaseCoreInternal (~> 11.6.0)
     - GoogleUtilities/Environment (~> 8.0)
     - GoogleUtilities/Logger (~> 8.0)
   - FirebaseCoreInternal (11.6.0):
     - "GoogleUtilities/NSData+zlib (~> 8.0)"
-  - FirebaseInstallations (11.4.0):
-    - FirebaseCore (~> 11.0)
+  - FirebaseInstallations (11.6.0):
+    - FirebaseCore (~> 11.6.0)
     - GoogleUtilities/Environment (~> 8.0)
     - GoogleUtilities/UserDefaults (~> 8.0)
     - PromisesObjC (~> 2.4)
-  - FirebaseMessaging (11.4.0):
-    - FirebaseCore (~> 11.0)
+  - FirebaseMessaging (11.6.0):
+    - FirebaseCore (~> 11.6.0)
     - FirebaseInstallations (~> 11.0)
     - GoogleDataTransport (~> 10.0)
     - GoogleUtilities/AppDelegateSwizzler (~> 8.0)
@@ -213,17 +213,17 @@ EXTERNAL SOURCES:
 
 SPEC CHECKSUMS:
   app_settings: 017320c6a680cdc94c799949d95b84cb69389ebc
-  device_info_plus: 97af1d7e84681a90d0693e63169a5d50e0839a0d
+  device_info_plus: bf2e3232933866d73fe290f2942f2156cdd10342
   DKImagePickerController: 946cec48c7873164274ecc4624d19e3da4c1ef3c
   DKPhotoGallery: b3834fecb755ee09a593d7c9e389d8b5d6deed60
   file_picker: 09aa5ec1ab24135ccd7a1621c46c84134bfd6655
-  Firebase: cf1b19f21410b029b6786a54e9764a0cacad3c99
-  firebase_core: b62a5080210edad3f2934314a8b2c6f5124e8e10
-  firebase_messaging: 98619a0572d82cfb3668e78859ba9f1110e268c9
-  FirebaseCore: e0510f1523bc0eb21653cac00792e1e2bd6f1771
+  Firebase: 374a441a91ead896215703a674d58cdb3e9d772b
+  firebase_core: feb37e79f775c2bd08dd35e02d83678291317e10
+  firebase_messaging: e2f0ba891b1509668c07f5099761518a5af8fe3c
+  FirebaseCore: 48b0dd707581cf9c1a1220da68223fb0a562afaa
   FirebaseCoreInternal: d98ab91e2d80a56d7b246856a8885443b302c0c2
-  FirebaseInstallations: 6ef4a1c7eb2a61ee1f74727d7f6ce2e72acf1414
-  FirebaseMessaging: f8a160d99c2c2e5babbbcc90c4a3e15db036aee2
+  FirebaseInstallations: efc0946fc756e4d22d8113f7c761948120322e8c
+  FirebaseMessaging: e1aca1fcc23e8b9eddb0e33f375ff90944623021
   Flutter: e0871f40cf51350855a761d2e70bf5af5b9b5de7
   GoogleDataTransport: aae35b7ea0c09004c3797d53c8c41f66f219d6a7
   GoogleUtilities: 26a3abef001b6533cf678d3eb38fd3f614b7872d
diff --git a/lib/api/exception.dart b/lib/api/exception.dart
index cda75b4b07..d4bebeeb62 100644
--- a/lib/api/exception.dart
+++ b/lib/api/exception.dart
@@ -28,19 +28,46 @@ sealed class ApiRequestException implements Exception {
   String toString() => message;
 }
 
-/// An error returned through the Zulip server API.
+/// A network-level error that prevented even getting an HTTP response
+/// to some Zulip API network request.
 ///
-/// See API docs: https://zulip.com/api/rest-error-handling
-class ZulipApiException extends ApiRequestException {
+/// This is the antonym of [HttpException].
+class NetworkException extends ApiRequestException {
+  /// The exception describing the underlying error.
+  ///
+  /// This can be any exception value that [http.Client.send] throws.
+  /// Ideally that would always be an [http.ClientException],
+  /// but empirically it can be [TlsException] and possibly others.
+  final Object cause;
 
-  /// The Zulip API error code returned by the server.
-  final String code;
+  NetworkException({required super.routeName, required super.message, required this.cause});
 
+  @override
+  String toString() {
+    return 'NetworkException: $message ($cause)';
+  }
+}
+
+/// Some kind of [ApiRequestException] that came as an HTTP response.
+///
+/// This is the antonym of [NetworkException].
+sealed class HttpException extends ApiRequestException {
   /// The HTTP status code returned by the server.
   ///
-  /// This is always in the range 400..499.
+  /// On [ZulipApiException], this is always in the range 400..499.
   final int httpStatus;
 
+  HttpException({required super.routeName, required this.httpStatus, required super.message});
+}
+
+/// An error returned through the Zulip server API,
+/// and with a 4xx HTTP status code.
+///
+/// See API docs: https://zulip.com/api/rest-error-handling
+class ZulipApiException extends HttpException {
+  /// The Zulip API error code returned by the server.
+  final String code;
+
   /// The error's JSON data, if any, beyond the properties common to all errors.
   ///
   /// This consists of the properties other than `result`, `code`, and `msg`.
@@ -50,8 +77,8 @@ class ZulipApiException extends ApiRequestException {
 
   ZulipApiException({
     required super.routeName,
+    required super.httpStatus,
     required this.code,
-    required this.httpStatus,
     required this.data,
     required super.message,
   }) : assert(400 <= httpStatus && httpStatus <= 499);
@@ -69,31 +96,12 @@ class ZulipApiException extends ApiRequestException {
   }
 }
 
-/// A network-level error that prevented even getting an HTTP response.
-class NetworkException extends ApiRequestException {
-  /// The exception describing the underlying error.
-  ///
-  /// This can be any exception value that [http.Client.send] throws.
-  /// Ideally that would always be an [http.ClientException],
-  /// but empirically it can be [TlsException] and possibly others.
-  final Object cause;
-
-  NetworkException({required super.routeName, required super.message, required this.cause});
-
-  @override
-  String toString() {
-    return 'NetworkException: $message ($cause)';
-  }
-}
-
 /// Some kind of server-side error in handling the request.
 ///
 /// This should always represent either some kind of operational issue
 /// on the server, or a bug in the server where its responses don't
 /// agree with the documented API.
-sealed class ServerException extends ApiRequestException {
-  final int httpStatus;
-
+sealed class ServerException extends HttpException {
   /// The response body, decoded as a JSON object.
   ///
   /// This is null if the body could not be read, or was not a valid JSON object.
@@ -101,7 +109,7 @@ sealed class ServerException extends ApiRequestException {
 
   ServerException({
     required super.routeName,
-    required this.httpStatus,
+    required super.httpStatus,
     required this.data,
     required super.message,
   });
diff --git a/lib/api/model/events.dart b/lib/api/model/events.dart
index 837aab120f..9faa3d367e 100644
--- a/lib/api/model/events.dart
+++ b/lib/api/model/events.dart
@@ -645,7 +645,7 @@ class UserTopicEvent extends Event {
   String get type => 'user_topic';
 
   final int streamId;
-  final String topicName;
+  final TopicName topicName;
   final int lastUpdated;
   final UserTopicVisibilityPolicy visibilityPolicy;
 
@@ -725,9 +725,9 @@ class UpdateMessageEvent extends Event {
   final PropagateMode? propagateMode;
 
   @JsonKey(name: 'orig_subject')
-  final String? origTopic;
+  final TopicName? origTopic;
   @JsonKey(name: 'subject')
-  final String? newTopic;
+  final TopicName? newTopic;
 
   // final List<TopicLink> topicLinks; // TODO handle
 
@@ -766,14 +766,6 @@ class UpdateMessageEvent extends Event {
   Map<String, dynamic> toJson() => _$UpdateMessageEventToJson(this);
 }
 
-/// As in [UpdateMessageEvent.propagateMode].
-@JsonEnum(fieldRename: FieldRename.snake)
-enum PropagateMode {
-  changeOne,
-  changeLater,
-  changeAll;
-}
-
 /// A Zulip event of type `delete_message`: https://zulip.com/api/get-events#delete_message
 @JsonSerializable(fieldRename: FieldRename.snake)
 class DeleteMessageEvent extends Event {
@@ -788,7 +780,7 @@ class DeleteMessageEvent extends Event {
   @MessageTypeConverter()
   final MessageType messageType;
   final int? streamId;
-  final String? topic;
+  final TopicName? topic;
 
   DeleteMessageEvent({
     required super.id,
@@ -924,7 +916,7 @@ class UpdateMessageFlagsMessageDetail {
   final bool? mentioned;
   final List<int>? userIds;
   final int? streamId;
-  final String? topic;
+  final TopicName? topic;
 
   UpdateMessageFlagsMessageDetail({
     required this.type,
@@ -1002,7 +994,7 @@ class TypingEvent extends Event {
   @JsonKey(name: 'recipients', fromJson: _recipientIdsFromJson)
   final List<int>? recipientIds;
   final int? streamId;
-  final String? topic;
+  final TopicName? topic;
 
   TypingEvent({
     required super.id,
diff --git a/lib/api/model/events.g.dart b/lib/api/model/events.g.dart
index 8f11b8b655..5d47444ecd 100644
--- a/lib/api/model/events.g.dart
+++ b/lib/api/model/events.g.dart
@@ -389,7 +389,7 @@ UserTopicEvent _$UserTopicEventFromJson(Map<String, dynamic> json) =>
     UserTopicEvent(
       id: (json['id'] as num).toInt(),
       streamId: (json['stream_id'] as num).toInt(),
-      topicName: json['topic_name'] as String,
+      topicName: TopicName.fromJson(json['topic_name'] as String),
       lastUpdated: (json['last_updated'] as num).toInt(),
       visibilityPolicy: $enumDecode(
           _$UserTopicVisibilityPolicyEnumMap, json['visibility_policy']),
@@ -430,8 +430,12 @@ UpdateMessageEvent _$UpdateMessageEventFromJson(Map<String, dynamic> json) =>
       newStreamId: (json['new_stream_id'] as num?)?.toInt(),
       propagateMode:
           $enumDecodeNullable(_$PropagateModeEnumMap, json['propagate_mode']),
-      origTopic: json['orig_subject'] as String?,
-      newTopic: json['subject'] as String?,
+      origTopic: json['orig_subject'] == null
+          ? null
+          : TopicName.fromJson(json['orig_subject'] as String),
+      newTopic: json['subject'] == null
+          ? null
+          : TopicName.fromJson(json['subject'] as String),
       origContent: json['orig_content'] as String?,
       origRenderedContent: json['orig_rendered_content'] as String?,
       content: json['content'] as String?,
@@ -451,7 +455,7 @@ Map<String, dynamic> _$UpdateMessageEventToJson(UpdateMessageEvent instance) =>
       'edit_timestamp': instance.editTimestamp,
       'stream_id': instance.origStreamId,
       'new_stream_id': instance.newStreamId,
-      'propagate_mode': _$PropagateModeEnumMap[instance.propagateMode],
+      'propagate_mode': instance.propagateMode,
       'orig_subject': instance.origTopic,
       'subject': instance.newTopic,
       'orig_content': instance.origContent,
@@ -487,7 +491,9 @@ DeleteMessageEvent _$DeleteMessageEventFromJson(Map<String, dynamic> json) =>
       messageType:
           const MessageTypeConverter().fromJson(json['message_type'] as String),
       streamId: (json['stream_id'] as num?)?.toInt(),
-      topic: json['topic'] as String?,
+      topic: json['topic'] == null
+          ? null
+          : TopicName.fromJson(json['topic'] as String),
     );
 
 Map<String, dynamic> _$DeleteMessageEventToJson(DeleteMessageEvent instance) =>
@@ -561,7 +567,9 @@ UpdateMessageFlagsMessageDetail _$UpdateMessageFlagsMessageDetailFromJson(
           ?.map((e) => (e as num).toInt())
           .toList(),
       streamId: (json['stream_id'] as num?)?.toInt(),
-      topic: json['topic'] as String?,
+      topic: json['topic'] == null
+          ? null
+          : TopicName.fromJson(json['topic'] as String),
     );
 
 Map<String, dynamic> _$UpdateMessageFlagsMessageDetailToJson(
@@ -609,7 +617,9 @@ TypingEvent _$TypingEventFromJson(Map<String, dynamic> json) => TypingEvent(
       senderId: (TypingEvent._readSenderId(json, 'sender_id') as num).toInt(),
       recipientIds: TypingEvent._recipientIdsFromJson(json['recipients']),
       streamId: (json['stream_id'] as num?)?.toInt(),
-      topic: json['topic'] as String?,
+      topic: json['topic'] == null
+          ? null
+          : TopicName.fromJson(json['topic'] as String),
     );
 
 Map<String, dynamic> _$TypingEventToJson(TypingEvent instance) =>
diff --git a/lib/api/model/initial_snapshot.dart b/lib/api/model/initial_snapshot.dart
index 6be0cadda9..1adc44196f 100644
--- a/lib/api/model/initial_snapshot.dart
+++ b/lib/api/model/initial_snapshot.dart
@@ -64,6 +64,13 @@ class InitialSnapshot {
 
   final List<UserTopicItem>? userTopics; // TODO(server-6)
 
+  /// The policy for who can use wildcard mentions in large channels.
+  ///
+  /// Search for "realm_wildcard_mention_policy" in https://zulip.com/api/register-queue.
+  final RealmWildcardMentionPolicy realmWildcardMentionPolicy;
+
+  final bool realmMandatoryTopics;
+
   /// The number of days until a user's account is treated as a full member.
   ///
   /// Search for "realm_waiting_period_threshold" in https://zulip.com/api/register-queue.
@@ -125,6 +132,8 @@ class InitialSnapshot {
     required this.streams,
     required this.userSettings,
     required this.userTopics,
+    required this.realmWildcardMentionPolicy,
+    required this.realmMandatoryTopics,
     required this.realmWaitingPeriodThreshold,
     required this.realmDefaultExternalAccounts,
     required this.maxFileUploadSizeMib,
@@ -148,6 +157,22 @@ enum EmailAddressVisibility {
   @JsonValue(5) moderators,
 }
 
+@JsonEnum(valueField: 'apiValue')
+enum RealmWildcardMentionPolicy {
+  everyone(apiValue: 1),
+  members(apiValue: 2),
+  fullMembers(apiValue: 3),
+  admins(apiValue: 5),
+  nobody(apiValue: 6),
+  moderators(apiValue: 7);
+
+  const RealmWildcardMentionPolicy({required this.apiValue});
+
+  final int? apiValue;
+
+  int? toJson() => apiValue;
+}
+
 /// An item in `realm_default_external_accounts`.
 ///
 /// For docs, search for "realm_default_external_accounts:"
@@ -231,7 +256,7 @@ class UserSettings {
 @JsonSerializable(fieldRename: FieldRename.snake)
 class UserTopicItem {
   final int streamId;
-  final String topicName;
+  final TopicName topicName;
   final int lastUpdated;
   @JsonKey(unknownEnumValue: UserTopicVisibilityPolicy.unknown)
   final UserTopicVisibilityPolicy visibilityPolicy;
@@ -310,7 +335,7 @@ class UnreadDmSnapshot {
 /// An item in [UnreadMessagesSnapshot.channels].
 @JsonSerializable(fieldRename: FieldRename.snake)
 class UnreadChannelSnapshot {
-  final String topic;
+  final TopicName topic;
   final int streamId;
   final List<int> unreadMessageIds;
 
diff --git a/lib/api/model/initial_snapshot.g.dart b/lib/api/model/initial_snapshot.g.dart
index 75472c1d7f..a69b6ebafe 100644
--- a/lib/api/model/initial_snapshot.g.dart
+++ b/lib/api/model/initial_snapshot.g.dart
@@ -58,6 +58,10 @@ InitialSnapshot _$InitialSnapshotFromJson(Map<String, dynamic> json) =>
       userTopics: (json['user_topics'] as List<dynamic>?)
           ?.map((e) => UserTopicItem.fromJson(e as Map<String, dynamic>))
           .toList(),
+      realmWildcardMentionPolicy: $enumDecode(
+          _$RealmWildcardMentionPolicyEnumMap,
+          json['realm_wildcard_mention_policy']),
+      realmMandatoryTopics: json['realm_mandatory_topics'] as bool,
       realmWaitingPeriodThreshold:
           (json['realm_waiting_period_threshold'] as num).toInt(),
       realmDefaultExternalAccounts:
@@ -108,6 +112,8 @@ Map<String, dynamic> _$InitialSnapshotToJson(InitialSnapshot instance) =>
       'streams': instance.streams,
       'user_settings': instance.userSettings,
       'user_topics': instance.userTopics,
+      'realm_wildcard_mention_policy': instance.realmWildcardMentionPolicy,
+      'realm_mandatory_topics': instance.realmMandatoryTopics,
       'realm_waiting_period_threshold': instance.realmWaitingPeriodThreshold,
       'realm_default_external_accounts': instance.realmDefaultExternalAccounts,
       'max_file_upload_size_mib': instance.maxFileUploadSizeMib,
@@ -125,6 +131,15 @@ const _$EmailAddressVisibilityEnumMap = {
   EmailAddressVisibility.moderators: 5,
 };
 
+const _$RealmWildcardMentionPolicyEnumMap = {
+  RealmWildcardMentionPolicy.everyone: 1,
+  RealmWildcardMentionPolicy.members: 2,
+  RealmWildcardMentionPolicy.fullMembers: 3,
+  RealmWildcardMentionPolicy.admins: 5,
+  RealmWildcardMentionPolicy.nobody: 6,
+  RealmWildcardMentionPolicy.moderators: 7,
+};
+
 RealmDefaultExternalAccount _$RealmDefaultExternalAccountFromJson(
         Map<String, dynamic> json) =>
     RealmDefaultExternalAccount(
@@ -188,7 +203,7 @@ const _$EmojisetEnumMap = {
 UserTopicItem _$UserTopicItemFromJson(Map<String, dynamic> json) =>
     UserTopicItem(
       streamId: (json['stream_id'] as num).toInt(),
-      topicName: json['topic_name'] as String,
+      topicName: TopicName.fromJson(json['topic_name'] as String),
       lastUpdated: (json['last_updated'] as num).toInt(),
       visibilityPolicy: $enumDecode(
           _$UserTopicVisibilityPolicyEnumMap, json['visibility_policy'],
@@ -260,7 +275,7 @@ Map<String, dynamic> _$UnreadDmSnapshotToJson(UnreadDmSnapshot instance) =>
 UnreadChannelSnapshot _$UnreadChannelSnapshotFromJson(
         Map<String, dynamic> json) =>
     UnreadChannelSnapshot(
-      topic: json['topic'] as String,
+      topic: TopicName.fromJson(json['topic'] as String),
       streamId: (json['stream_id'] as num).toInt(),
       unreadMessageIds: (json['unread_message_ids'] as List<dynamic>)
           .map((e) => (e as num).toInt())
diff --git a/lib/api/model/model.dart b/lib/api/model/model.dart
index b36e1f2490..fad8ddc5bc 100644
--- a/lib/api/model/model.dart
+++ b/lib/api/model/model.dart
@@ -556,11 +556,11 @@ sealed class Message {
   final String senderFullName;
   final int senderId;
   final String senderRealmStr;
-  @JsonKey(name: 'subject')
-  String topic;
+
   /// Poll data if "submessages" describe a poll, `null` otherwise.
   @JsonKey(name: 'submessages', readValue: _readPoll, fromJson: Poll.fromJson, toJson: Poll.toJson)
   Poll? poll;
+
   final int timestamp;
   String get type;
 
@@ -613,7 +613,6 @@ sealed class Message {
     required this.senderFullName,
     required this.senderId,
     required this.senderRealmStr,
-    required this.topic,
     required this.timestamp,
     required this.flags,
     required this.matchContent,
@@ -656,6 +655,65 @@ enum MessageFlag {
   String toJson() => _$MessageFlagEnumMap[this]!;
 }
 
+/// The name of a Zulip topic.
+// TODO(dart): Can we forbid calling Object members on this extension type?
+//   (The lack of "implements Object" ought to do that, but doesn't.)
+//   In particular an interpolation "foo > $topic" is a bug we'd like to catch.
+// TODO(dart): Can we forbid using this extension type as a key in a Map?
+//   (The lack of "implements Object" arguably should do that, but doesn't.)
+//   Using as a Map key is almost certainly a bug because it won't case-fold;
+//   see for example #739, #980, #1205.
+extension type const TopicName(String _value) {
+  /// The canonical form of the resolved-topic prefix.
+  // This is RESOLVED_TOPIC_PREFIX in web:
+  //   https://github.com/zulip/zulip/blob/1fac99733/web/shared/src/resolved_topic.ts
+  static const resolvedTopicPrefix = '✔ ';
+
+  /// Pattern for an arbitrary resolved-topic prefix.
+  ///
+  /// These always begin with [resolvedTopicPrefix]
+  /// but can be weird and go on longer, like "✔ ✔✔ ".
+  // This is RESOLVED_TOPIC_PREFIX_RE in web:
+  //   https://github.com/zulip/zulip/blob/1fac99733/web/shared/src/resolved_topic.ts#L4-L12
+  static final resolvedTopicPrefixRegexp = RegExp(r'^✔ [ ✔]*');
+
+  /// The string this topic is identified by in the Zulip API.
+  ///
+  /// This should be used in constructing HTTP requests to the server,
+  /// but rarely for other purposes.  See [displayName] and [canonicalize].
+  String get apiName => _value;
+
+  /// The string this topic is displayed as to the user in our UI.
+  ///
+  /// At the moment this always equals [apiName].
+  /// In the future this will become null for the "general chat" topic (#1250),
+  /// so that UI code can identify when it needs to represent the topic
+  /// specially in the way prescribed for "general chat".
+  // TODO(#1250) carry out that plan
+  String get displayName => _value;
+
+  /// The key to use for "same topic as" comparisons.
+  String canonicalize() => apiName.toLowerCase();
+
+  /// Whether the topic starts with [resolvedTopicPrefix].
+  bool get isResolved => _value.startsWith(resolvedTopicPrefix);
+
+  /// This [TopicName] plus the [resolvedTopicPrefix] prefix.
+  TopicName resolve() => TopicName(resolvedTopicPrefix + _value);
+
+  /// A [TopicName] with [resolvedTopicPrefixRegexp] stripped if present.
+  TopicName unresolve() =>
+    TopicName(_value.replaceFirst(resolvedTopicPrefixRegexp, ''));
+
+  /// Whether [this] and [other] have the same canonical form,
+  /// using [canonicalize].
+  bool isSameAs(TopicName other) => canonicalize() == other.canonicalize();
+
+  TopicName.fromJson(this._value);
+
+  String toJson() => apiName;
+}
+
 @JsonSerializable(fieldRename: FieldRename.snake)
 class StreamMessage extends Message {
   @override
@@ -667,8 +725,16 @@ class StreamMessage extends Message {
   // invalidated.
   @JsonKey(required: true, disallowNullValue: true)
   String? displayRecipient;
+
   int streamId;
 
+  // The topic/subject is documented to be present on DMs too, just empty.
+  // We ignore it on DMs; if a future server introduces distinct topics in DMs,
+  // that will need new UI that we'll design then as part of that feature,
+  // and ignoring the topics seems as good a fallback behavior as any.
+  @JsonKey(name: 'subject')
+  TopicName topic;
+
   StreamMessage({
     required super.client,
     required super.content,
@@ -683,13 +749,13 @@ class StreamMessage extends Message {
     required super.senderFullName,
     required super.senderId,
     required super.senderRealmStr,
-    required super.topic,
     required super.timestamp,
     required super.flags,
     required super.matchContent,
     required super.matchTopic,
     required this.displayRecipient,
     required this.streamId,
+    required this.topic,
   });
 
   factory StreamMessage.fromJson(Map<String, dynamic> json) =>
@@ -786,7 +852,6 @@ class DmMessage extends Message {
     required super.senderFullName,
     required super.senderId,
     required super.senderRealmStr,
-    required super.topic,
     required super.timestamp,
     required super.flags,
     required super.matchContent,
@@ -806,25 +871,28 @@ enum MessageEditState {
   edited,
   moved;
 
-  // Adapted from the shared code:
-  //   https://github.com/zulip/zulip/blob/1fac99733/web/shared/src/resolved_topic.ts
-  // The canonical resolved-topic prefix.
-  static const String _resolvedTopicPrefix = '✔ ';
-
   /// Whether the given topic move reflected either a "resolve topic"
   /// or "unresolve topic" operation.
   ///
   /// The Zulip "resolved topics" feature is implemented by renaming the topic;
   /// but for purposes of [Message.editState], we want to ignore such renames.
   /// This method identifies topic moves that should be ignored in that context.
-  static bool topicMoveWasResolveOrUnresolve(String topic, String prevTopic) {
-    if (topic.startsWith(_resolvedTopicPrefix)
-        && topic.substring(_resolvedTopicPrefix.length) == prevTopic) {
+  static bool topicMoveWasResolveOrUnresolve(TopicName topic, TopicName prevTopic) {
+    // Implemented to match web; see analyze_edit_history in zulip/zulip's
+    // web/src/message_list_view.ts.
+    //
+    // Also, this is a hot codepath (decoding messages, a high-volume type of
+    // data we get from the server), so we avoid calling [canonicalize] and
+    // using [TopicName.resolvedTopicPrefixRegexp], to be performance-sensitive.
+    // Discussion:
+    //   https://github.com/zulip/zulip-flutter/pull/1242#discussion_r1917592157
+    if (topic.apiName.startsWith(TopicName.resolvedTopicPrefix)
+        && topic.apiName.substring(TopicName.resolvedTopicPrefix.length) == prevTopic.apiName) {
       return true;
     }
 
-    if (prevTopic.startsWith(_resolvedTopicPrefix)
-        && prevTopic.substring(_resolvedTopicPrefix.length) == topic) {
+    if (prevTopic.apiName.startsWith(TopicName.resolvedTopicPrefix)
+        && prevTopic.apiName.substring(TopicName.resolvedTopicPrefix.length) == topic.apiName) {
       return true;
     }
 
@@ -857,8 +925,10 @@ enum MessageEditState {
       }
 
       // TODO(server-5) prev_subject was the old name of prev_topic on pre-5.0 servers
-      final prevTopic = (entry['prev_topic'] ?? entry['prev_subject']) as String?;
-      final topic = entry['topic'] as String?;
+      final prevTopicStr = (entry['prev_topic'] ?? entry['prev_subject']) as String?;
+      final prevTopic = prevTopicStr == null ? null : TopicName.fromJson(prevTopicStr);
+      final topicStr = entry['topic'] as String?;
+      final topic = topicStr == null ? null : TopicName.fromJson(topicStr);
       if (prevTopic != null) {
         // TODO(server-5) pre-5.0 servers do not have the 'topic' field
         if (topic == null) {
@@ -875,3 +945,13 @@ enum MessageEditState {
     return MessageEditState.none;
   }
 }
+
+/// As in [updateMessage] or [UpdateMessageEvent.propagateMode].
+@JsonEnum(fieldRename: FieldRename.snake, alwaysCreate: true)
+enum PropagateMode {
+  changeOne,
+  changeLater,
+  changeAll;
+
+  String toJson() => _$PropagateModeEnumMap[this]!;
+}
diff --git a/lib/api/model/model.g.dart b/lib/api/model/model.g.dart
index 2c5adbe15c..cfa38aec5f 100644
--- a/lib/api/model/model.g.dart
+++ b/lib/api/model/model.g.dart
@@ -267,13 +267,13 @@ StreamMessage _$StreamMessageFromJson(Map<String, dynamic> json) {
     senderFullName: json['sender_full_name'] as String,
     senderId: (json['sender_id'] as num).toInt(),
     senderRealmStr: json['sender_realm_str'] as String,
-    topic: json['subject'] as String,
     timestamp: (json['timestamp'] as num).toInt(),
     flags: Message._flagsFromJson(json['flags']),
     matchContent: json['match_content'] as String?,
     matchTopic: json['match_subject'] as String?,
     displayRecipient: json['display_recipient'] as String?,
     streamId: (json['stream_id'] as num).toInt(),
+    topic: TopicName.fromJson(json['subject'] as String),
   )..poll = Poll.fromJson(Message._readPoll(json, 'submessages'));
 }
 
@@ -292,7 +292,6 @@ Map<String, dynamic> _$StreamMessageToJson(StreamMessage instance) =>
       'sender_full_name': instance.senderFullName,
       'sender_id': instance.senderId,
       'sender_realm_str': instance.senderRealmStr,
-      'subject': instance.topic,
       'submessages': Poll.toJson(instance.poll),
       'timestamp': instance.timestamp,
       'flags': instance.flags,
@@ -302,6 +301,7 @@ Map<String, dynamic> _$StreamMessageToJson(StreamMessage instance) =>
       if (instance.displayRecipient case final value?)
         'display_recipient': value,
       'stream_id': instance.streamId,
+      'subject': instance.topic,
     };
 
 const _$MessageEditStateEnumMap = {
@@ -338,7 +338,6 @@ DmMessage _$DmMessageFromJson(Map<String, dynamic> json) => DmMessage(
       senderFullName: json['sender_full_name'] as String,
       senderId: (json['sender_id'] as num).toInt(),
       senderRealmStr: json['sender_realm_str'] as String,
-      topic: json['subject'] as String,
       timestamp: (json['timestamp'] as num).toInt(),
       flags: Message._flagsFromJson(json['flags']),
       matchContent: json['match_content'] as String?,
@@ -361,7 +360,6 @@ Map<String, dynamic> _$DmMessageToJson(DmMessage instance) => <String, dynamic>{
       'sender_full_name': instance.senderFullName,
       'sender_id': instance.senderId,
       'sender_realm_str': instance.senderRealmStr,
-      'subject': instance.topic,
       'submessages': Poll.toJson(instance.poll),
       'timestamp': instance.timestamp,
       'flags': instance.flags,
@@ -405,3 +403,9 @@ const _$MessageFlagEnumMap = {
   MessageFlag.historical: 'historical',
   MessageFlag.unknown: 'unknown',
 };
+
+const _$PropagateModeEnumMap = {
+  PropagateMode.changeOne: 'change_one',
+  PropagateMode.changeLater: 'change_later',
+  PropagateMode.changeAll: 'change_all',
+};
diff --git a/lib/api/model/narrow.dart b/lib/api/model/narrow.dart
index 3ec08a4fe4..8082ac64ff 100644
--- a/lib/api/model/narrow.dart
+++ b/lib/api/model/narrow.dart
@@ -1,5 +1,7 @@
 import 'package:json_annotation/json_annotation.dart';
 
+import 'model.dart';
+
 part 'narrow.g.dart';
 
 typedef ApiNarrow = List<ApiNarrowElement>;
@@ -26,7 +28,37 @@ ApiNarrow resolveDmElements(ApiNarrow narrow, int zulipFeatureLevel) {
 /// please add more as needed.
 sealed class ApiNarrowElement {
   String get operator;
-  Object get operand;
+
+  /// The operand of this narrow filter.
+  ///
+  /// The base-class getter [ApiNarrowElement.operand] returns `dynamic`,
+  /// and its value should only be used for encoding as JSON, for use in a
+  /// request to the Zulip server.
+  ///
+  /// For any operations that depend more specifically on the operand's type,
+  /// do not use run-time type checks on the value of [operand]; instead, make
+  /// a run-time type check (e.g. with `switch`) on the [ApiNarrowElement]
+  /// itself, and use the [operand] getter of the specific subtype.
+  ///
+  /// That makes a difference because [ApiNarrowTopic.operand] has type
+  /// [TopicName]; at runtime a [TopicName] is indistinguishable from [String],
+  /// but an [ApiNarrowTopic] can still be distinguished from other subclasses.
+  //
+  // We can't just write [Object] here; if we do, the compiler rejects the
+  // override in ApiNarrowTopic because TopicName can't be assigned to Object.
+  // The reason that could be bad is that a caller of [ApiNarrowElement.operand]
+  // could take the result and call Object members on it, like toString, even
+  // though TopicName doesn't declare those members.
+  //
+  // In this case that's fine because the only plausible thing to do with
+  // a generic [ApiNarrowElement.operand] is to encode it as JSON anyway,
+  // which behaves just fine on TopicName.
+  //
+  // ... Even if it weren't fine, in the case of Object this protection is
+  // thoroughly undermined already: code that has a TopicName can call Object
+  // members on it directly.  See comments at [TopicName].
+  dynamic get operand; // see justification for `dynamic` above
+
   final bool negated;
 
   ApiNarrowElement({this.negated = false});
@@ -54,12 +86,12 @@ class ApiNarrowStream extends ApiNarrowElement {
 class ApiNarrowTopic extends ApiNarrowElement {
   @override String get operator => 'topic';
 
-  @override final String operand;
+  @override final TopicName operand;
 
   ApiNarrowTopic(this.operand, {super.negated});
 
   factory ApiNarrowTopic.fromJson(Map<String, dynamic> json) => ApiNarrowTopic(
-    json['operand'] as String,
+    TopicName.fromJson(json['operand'] as String),
     negated: json['negated'] as bool? ?? false,
   );
 }
diff --git a/lib/api/notifications.dart b/lib/api/notifications.dart
index 2337c0456e..6d028aa267 100644
--- a/lib/api/notifications.dart
+++ b/lib/api/notifications.dart
@@ -1,6 +1,8 @@
 
 import 'package:json_annotation/json_annotation.dart';
 
+import 'model/model.dart';
+
 part 'notifications.g.dart';
 
 /// Parsed version of an FCM message, of any type.
@@ -187,7 +189,7 @@ class FcmMessageChannelRecipient extends FcmMessageRecipient {
   @JsonKey(name: 'stream')
   final String? streamName;
 
-  final String topic;
+  final TopicName topic;
 
   FcmMessageChannelRecipient({required this.streamId, required this.streamName, required this.topic});
 
diff --git a/lib/api/notifications.g.dart b/lib/api/notifications.g.dart
index 4a9752a9af..b56412f1fd 100644
--- a/lib/api/notifications.g.dart
+++ b/lib/api/notifications.g.dart
@@ -47,7 +47,7 @@ FcmMessageChannelRecipient _$FcmMessageChannelRecipientFromJson(
     FcmMessageChannelRecipient(
       streamId: const _IntConverter().fromJson(json['stream_id'] as String),
       streamName: json['stream'] as String?,
-      topic: json['topic'] as String,
+      topic: TopicName.fromJson(json['topic'] as String),
     );
 
 RemoveFcmMessage _$RemoveFcmMessageFromJson(Map<String, dynamic> json) =>
diff --git a/lib/api/route/channels.dart b/lib/api/route/channels.dart
index 00832f7fd0..bfa46f5ab8 100644
--- a/lib/api/route/channels.dart
+++ b/lib/api/route/channels.dart
@@ -28,7 +28,7 @@ class GetStreamTopicsResult {
 @JsonSerializable(fieldRename: FieldRename.snake)
 class GetStreamTopicsEntry {
   final int maxId;
-  final String name;
+  final TopicName name;
 
   GetStreamTopicsEntry({
     required this.maxId,
@@ -46,7 +46,7 @@ class GetStreamTopicsEntry {
 // TODO(server-7): remove this and just use updateUserTopic
 Future<void> updateUserTopicCompat(ApiConnection connection, {
   required int streamId,
-  required String topic,
+  required TopicName topic,
   required UserTopicVisibilityPolicy visibilityPolicy,
 }) {
   final useLegacyApi = connection.zulipFeatureLevel! < 170;
@@ -59,7 +59,7 @@ Future<void> updateUserTopicCompat(ApiConnection connection, {
     // https://zulip.com/api/mute-topic
     return connection.patch('muteTopic', (_) {}, 'users/me/subscriptions/muted_topics', {
       'stream_id': streamId,
-      'topic': RawParameter(topic),
+      'topic': RawParameter(topic.apiName),
       'op': RawParameter(op),
     });
   } else {
@@ -76,14 +76,14 @@ Future<void> updateUserTopicCompat(ApiConnection connection, {
 // TODO(server-7) remove FL 170+ mention in doc, and the related `assert`
 Future<void> updateUserTopic(ApiConnection connection, {
   required int streamId,
-  required String topic,
+  required TopicName topic,
   required UserTopicVisibilityPolicy visibilityPolicy,
 }) {
   assert(visibilityPolicy != UserTopicVisibilityPolicy.unknown);
   assert(connection.zulipFeatureLevel! >= 170);
   return connection.post('updateUserTopic', (_) {}, 'user_topics', {
     'stream_id': streamId,
-    'topic': RawParameter(topic),
+    'topic': RawParameter(topic.apiName),
     'visibility_policy': visibilityPolicy,
   });
 }
diff --git a/lib/api/route/channels.g.dart b/lib/api/route/channels.g.dart
index 561b43f005..4a5f7009c3 100644
--- a/lib/api/route/channels.g.dart
+++ b/lib/api/route/channels.g.dart
@@ -26,7 +26,7 @@ GetStreamTopicsEntry _$GetStreamTopicsEntryFromJson(
         Map<String, dynamic> json) =>
     GetStreamTopicsEntry(
       maxId: (json['max_id'] as num).toInt(),
-      name: json['name'] as String,
+      name: TopicName.fromJson(json['name'] as String),
     );
 
 Map<String, dynamic> _$GetStreamTopicsEntryToJson(
diff --git a/lib/api/route/messages.dart b/lib/api/route/messages.dart
index 26fd80f3ac..be6728c790 100644
--- a/lib/api/route/messages.dart
+++ b/lib/api/route/messages.dart
@@ -156,7 +156,7 @@ class GetMessagesResult {
 }
 
 // https://zulip.com/api/send-message#parameter-topic
-const int kMaxTopicLength = 60;
+const int kMaxTopicLengthCodePoints = 60;
 
 // https://zulip.com/api/send-message#parameter-content
 const int kMaxMessageLengthCodePoints = 10000;
@@ -186,7 +186,7 @@ Future<SendMessageResult> sendMessage(
       StreamDestination() => {
         'type': RawParameter('stream'),
         'to': destination.streamId,
-        'topic': RawParameter(destination.topic),
+        'topic': RawParameter(destination.topic.apiName),
       },
       DmDestination() => {
         'type': supportsTypeDirect ? RawParameter('direct') : RawParameter('private'),
@@ -231,7 +231,7 @@ class StreamDestination extends MessageDestination {
   const StreamDestination(this.streamId, this.topic);
 
   final int streamId;
-  final String topic;
+  final TopicName topic;
 }
 
 /// A DM conversation, for specifying to [sendMessage].
@@ -258,6 +258,39 @@ class SendMessageResult {
   Map<String, dynamic> toJson() => _$SendMessageResultToJson(this);
 }
 
+/// https://zulip.com/api/update-message
+Future<UpdateMessageResult> updateMessage(
+  ApiConnection connection, {
+  required int messageId,
+  TopicName? topic,
+  PropagateMode? propagateMode,
+  bool? sendNotificationToOldThread,
+  bool? sendNotificationToNewThread,
+  String? content,
+  int? streamId,
+}) {
+  return connection.patch('updateMessage', UpdateMessageResult.fromJson, 'messages/$messageId', {
+    if (topic != null) 'topic': RawParameter(topic.apiName),
+    if (propagateMode != null) 'propagate_mode': RawParameter(propagateMode.toJson()),
+    if (sendNotificationToOldThread != null) 'send_notification_to_old_thread': sendNotificationToOldThread,
+    if (sendNotificationToNewThread != null) 'send_notification_to_new_thread': sendNotificationToNewThread,
+    if (content != null) 'content': RawParameter(content),
+    if (streamId != null) 'stream_id': streamId,
+  });
+}
+
+@JsonSerializable(fieldRename: FieldRename.snake)
+class UpdateMessageResult {
+  // final List<DetachedUpload> detachedUploads; // TODO handle
+
+  UpdateMessageResult();
+
+  factory UpdateMessageResult.fromJson(Map<String, dynamic> json) =>
+    _$UpdateMessageResultFromJson(json);
+
+  Map<String, dynamic> toJson() => _$UpdateMessageResultToJson(this);
+}
+
 /// https://zulip.com/api/upload-file
 Future<UploadFileResult> uploadFile(
   ApiConnection connection, {
@@ -449,10 +482,10 @@ Future<void> markStreamAsRead(ApiConnection connection, {
 // TODO(server-6): Remove as deprecated by updateMessageFlagsForNarrow
 Future<void> markTopicAsRead(ApiConnection connection, {
   required int streamId,
-  required String topicName,
+  required TopicName topicName,
 }) {
   return connection.post('markTopicAsRead', (_) {}, 'mark_topic_as_read', {
     'stream_id': streamId,
-    'topic_name': RawParameter(topicName),
+    'topic_name': RawParameter(topicName.apiName),
   });
 }
diff --git a/lib/api/route/messages.g.dart b/lib/api/route/messages.g.dart
index 161ea7588e..3a449d73ac 100644
--- a/lib/api/route/messages.g.dart
+++ b/lib/api/route/messages.g.dart
@@ -50,6 +50,13 @@ Map<String, dynamic> _$SendMessageResultToJson(SendMessageResult instance) =>
       'id': instance.id,
     };
 
+UpdateMessageResult _$UpdateMessageResultFromJson(Map<String, dynamic> json) =>
+    UpdateMessageResult();
+
+Map<String, dynamic> _$UpdateMessageResultToJson(
+        UpdateMessageResult instance) =>
+    <String, dynamic>{};
+
 UploadFileResult _$UploadFileResultFromJson(Map<String, dynamic> json) =>
     UploadFileResult(
       uri: json['uri'] as String,
diff --git a/lib/api/route/typing.dart b/lib/api/route/typing.dart
index b9f8503172..8e2e5dae6b 100644
--- a/lib/api/route/typing.dart
+++ b/lib/api/route/typing.dart
@@ -17,7 +17,7 @@ Future<void> setTypingStatus(ApiConnection connection, {
         'type':  RawParameter(supportsTypeChannel ? 'channel' : 'stream'),
         if (supportsStreamId) 'stream_id': destination.streamId
         else                  'to': [destination.streamId],
-        'topic': RawParameter(destination.topic),
+        'topic': RawParameter(destination.topic.apiName),
       });
     case DmDestination():
       final supportsDirect = connection.zulipFeatureLevel! >= 174; // TODO(server-7)
diff --git a/lib/example/sticky_header.dart b/lib/example/sticky_header.dart
new file mode 100644
index 0000000000..3fa2185c1a
--- /dev/null
+++ b/lib/example/sticky_header.dart
@@ -0,0 +1,428 @@
+/// Example app for exercising the sticky_header library.
+///
+/// This is useful when developing changes to [StickyHeaderListView],
+/// [SliverStickyHeaderList], and [StickyHeaderItem],
+/// for experimenting visually with changes.
+///
+/// To use this example app, run the command:
+///     flutter run lib/example/sticky_header.dart
+/// or run this file from your IDE.
+///
+/// One inconvenience: this means the example app will use the same app ID
+/// as the actual Zulip app.  The app's data remains untouched, though, so
+/// a normal `flutter run` will put things back as they were.
+/// This inconvenience could be fixed with a bit more work: we'd use
+/// `flutter run --flavor`, and define an Android flavor in build.gradle
+/// and an Xcode scheme in the iOS build config
+/// so as to set the app ID differently.
+library;
+
+import 'package:flutter/material.dart';
+
+import '../widgets/sticky_header.dart';
+
+/// Example page using [StickyHeaderListView] and [StickyHeaderItem] in a
+/// vertically-scrolling list.
+class ExampleVertical extends StatelessWidget {
+  ExampleVertical({
+    super.key,
+    required this.title,
+    this.reverse = false,
+    this.headerDirection = AxisDirection.down,
+  }) : assert(axisDirectionToAxis(headerDirection) == Axis.vertical);
+
+  final String title;
+  final bool reverse;
+  final AxisDirection headerDirection;
+
+  @override
+  Widget build(BuildContext context) {
+    final headerAtBottom = axisDirectionIsReversed(headerDirection);
+
+    const numSections = 100;
+    const numPerSection = 10;
+    return Scaffold(
+      appBar: AppBar(title: Text(title)),
+
+      // Invoke StickyHeaderListView the same way you'd invoke ListView.
+      // The constructor takes the same arguments.
+      body: StickyHeaderListView.separated(
+        reverse: reverse,
+        reverseHeader: headerAtBottom,
+        itemCount: numSections,
+        separatorBuilder: (context, i) => const SizedBox.shrink(),
+
+        // Use StickyHeaderItem as an item widget in the ListView.
+        // A header will float over the item as needed in order to
+        // "stick" at the edge of the viewport.
+        //
+        // You can also include non-StickyHeaderItem items in the list.
+        // They'll behave just like in a plain ListView.
+        //
+        // Each StickyHeaderItem needs to be an item directly in the list, not
+        // wrapped inside other widgets that affect layout, in order to get
+        // the sticky-header behavior.
+        itemBuilder: (context, i) => StickyHeaderItem(
+          header: WideHeader(i: i),
+          child: Column(
+            verticalDirection: headerAtBottom
+              ? VerticalDirection.up : VerticalDirection.down,
+            children: List.generate(
+              numPerSection + 1, (j) {
+                if (j == 0) return WideHeader(i: i);
+                return WideItem(i: i, j: j-1);
+              })))));
+  }
+}
+
+/// Example page using [StickyHeaderListView] and [StickyHeaderItem] in a
+/// horizontally-scrolling list.
+class ExampleHorizontal extends StatelessWidget {
+  ExampleHorizontal({
+    super.key,
+    required this.title,
+    this.reverse = false,
+    required this.headerDirection,
+  }) : assert(axisDirectionToAxis(headerDirection) == Axis.horizontal);
+
+  final String title;
+  final bool reverse;
+  final AxisDirection headerDirection;
+
+  @override
+  Widget build(BuildContext context) {
+    final headerAtRight = axisDirectionIsReversed(headerDirection);
+    const numSections = 100;
+    const numPerSection = 10;
+    return Scaffold(
+      appBar: AppBar(title: Text(title)),
+      body: StickyHeaderListView.separated(
+
+        // StickyHeaderListView and StickyHeaderItem also work for horizontal
+        // scrolling.  Pass `scrollDirection: Axis.horizontal` to the
+        // StickyHeaderListView constructor, just like for ListView.
+        scrollDirection: Axis.horizontal,
+        reverse: reverse,
+        reverseHeader: headerAtRight,
+        itemCount: numSections,
+        separatorBuilder: (context, i) => const SizedBox.shrink(),
+        itemBuilder: (context, i) => StickyHeaderItem(
+          header: TallHeader(i: i),
+          child: Row(
+            textDirection: headerAtRight ? TextDirection.rtl : TextDirection.ltr,
+            children: List.generate(
+              numPerSection + 1,
+              (j) {
+                if (j == 0) return TallHeader(i: i);
+                return TallItem(i: i, j: j-1, numPerSection: numPerSection);
+              })))));
+  }
+}
+
+/// An experimental example approximating the Zulip message list.
+class ExampleVerticalDouble extends StatelessWidget {
+  const ExampleVerticalDouble({
+    super.key,
+    required this.title,
+    // this.reverse = false,
+    // this.headerDirection = AxisDirection.down,
+  }); // : assert(axisDirectionToAxis(headerDirection) == Axis.vertical);
+
+  final String title;
+  // final bool reverse;
+  // final AxisDirection headerDirection;
+
+  @override
+  Widget build(BuildContext context) {
+    const centerSliverKey = ValueKey('center sliver');
+    const numSections = 100;
+    const numBottomSections = 2;
+    const numPerSection = 10;
+    return Scaffold(
+      appBar: AppBar(title: Text(title)),
+      body: CustomScrollView(
+        semanticChildCount: numSections,
+        anchor: 0.5,
+        center: centerSliverKey,
+        slivers: [
+          SliverStickyHeaderList(
+            headerPlacement: HeaderPlacement.scrollingStart,
+            delegate: SliverChildBuilderDelegate(
+              childCount: numSections - numBottomSections,
+              (context, i) {
+                final ii = i + numBottomSections;
+                return StickyHeaderItem(
+                  header: WideHeader(i: ii),
+                  child: Column(
+                    children: List.generate(numPerSection + 1, (j) {
+                      if (j == 0) return WideHeader(i: ii);
+                      return WideItem(i: ii, j: j-1);
+                    })));
+              })),
+          SliverStickyHeaderList(
+            key: centerSliverKey,
+            headerPlacement: HeaderPlacement.scrollingStart,
+            delegate: SliverChildBuilderDelegate(
+              childCount: numBottomSections,
+              (context, i) {
+                final ii = numBottomSections - 1 - i;
+                return StickyHeaderItem(
+                  header: WideHeader(i: ii),
+                  child: Column(
+                    children: List.generate(numPerSection + 1, (j) {
+                        if (j == 0) return WideHeader(i: ii);
+                        return WideItem(i: ii, j: j-1);
+                      })));
+              })),
+        ]));
+  }
+}
+
+////////////////////////////////////////////////////////////////////////////
+//
+// That's it!
+//
+// The rest of this file is boring infrastructure for navigating to the
+// different examples, and for having some content to put inside them.
+//
+////////////////////////////////////////////////////////////////////////////
+
+class WideHeader extends StatelessWidget {
+  const WideHeader({super.key, required this.i});
+
+  final int i;
+
+  @override
+  Widget build(BuildContext context) {
+    return Material(
+      color: Theme.of(context).colorScheme.primaryContainer,
+      child: ListTile(
+        title: Text("Section ${i + 1}",
+          style: TextStyle(
+            color: Theme.of(context).colorScheme.onPrimaryContainer))));
+  }
+}
+
+class WideItem extends StatelessWidget {
+  const WideItem({super.key, required this.i, required this.j});
+
+  final int i;
+  final int j;
+
+  @override
+  Widget build(BuildContext context) {
+    return ListTile(title: Text("Item ${i + 1}.${j + 1}"));
+  }
+}
+
+class TallHeader extends StatelessWidget {
+  const TallHeader({super.key, required this.i});
+
+  final int i;
+
+  @override
+  Widget build(BuildContext context) {
+    final contents = Column(children: [
+      Text("Section ${i + 1}",
+        style: TextStyle(
+          fontWeight: FontWeight.bold,
+          color: Theme.of(context).colorScheme.onPrimaryContainer)),
+      const SizedBox(height: 8),
+      const Expanded(child: SizedBox.shrink()),
+      const SizedBox(height: 8),
+      const Text("end"),
+    ]);
+
+    return Container(
+      alignment: Alignment.center,
+      child: Card(
+        color: Theme.of(context).colorScheme.primaryContainer,
+        child: Padding(padding: const EdgeInsets.all(8), child: contents)));
+  }
+}
+
+class TallItem extends StatelessWidget {
+  const TallItem({super.key,
+    required this.i,
+    required this.j,
+    required this.numPerSection,
+  });
+
+  final int i;
+  final int j;
+  final int numPerSection;
+
+  @override
+  Widget build(BuildContext context) {
+    final heightFactor = (1 + j) / numPerSection;
+
+    final contents = Column(children: [
+      Text("Item ${i + 1}.${j + 1}"),
+      const SizedBox(height: 8),
+      Expanded(
+        child: FractionallySizedBox(
+          heightFactor: heightFactor,
+          child: ColoredBox(
+            color: Theme.of(context).colorScheme.secondary,
+            child: const SizedBox(width: 4)))),
+      const SizedBox(height: 8),
+      const Text("end"),
+    ]);
+
+    return Container(
+      alignment: Alignment.center,
+      child: Card(
+        child: Padding(padding: const EdgeInsets.all(8), child: contents)));
+  }
+}
+
+enum _ExampleType { vertical, horizontal }
+
+class MainPage extends StatelessWidget {
+  const MainPage({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final verticalItems = [
+      _buildItem(context, _ExampleType.vertical,
+        primary: true,
+        title: 'Scroll down, headers at top (a standard list)',
+        headerDirection: AxisDirection.down),
+      _buildItem(context, _ExampleType.vertical,
+        title: 'Scroll up, headers at top',
+        reverse: true,
+        headerDirection: AxisDirection.down),
+      _buildItem(context, _ExampleType.vertical,
+        title: 'Scroll down, headers at bottom',
+        headerDirection: AxisDirection.up),
+      _buildItem(context, _ExampleType.vertical,
+        title: 'Scroll up, headers at bottom',
+        reverse: true,
+        headerDirection: AxisDirection.up),
+    ];
+    final horizontalItems = [
+      _buildItem(context, _ExampleType.horizontal,
+        title: 'Scroll right, headers at left',
+        headerDirection: AxisDirection.right),
+      _buildItem(context, _ExampleType.horizontal,
+        title: 'Scroll left, headers at left',
+        reverse: true,
+        headerDirection: AxisDirection.right),
+      _buildItem(context, _ExampleType.horizontal,
+        title: 'Scroll right, headers at right',
+        headerDirection: AxisDirection.left),
+      _buildItem(context, _ExampleType.horizontal,
+        title: 'Scroll left, headers at right',
+        reverse: true,
+        headerDirection: AxisDirection.left),
+    ];
+    final otherItems = [
+      _buildButton(context,
+        title: 'Double slivers',
+        page: ExampleVerticalDouble(title: 'Double slivers')),
+    ];
+    return Scaffold(
+        appBar: AppBar(title: const Text('Sticky Headers example')),
+        body: CustomScrollView(slivers: [
+          SliverToBoxAdapter(
+            child: Padding(
+              padding: const EdgeInsets.only(top: 24),
+              child: Center(
+                child: Text("Vertical lists",
+                  style: Theme.of(context).textTheme.headlineMedium)))),
+          SliverPadding(
+            padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 16),
+            sliver: SliverGrid.count(
+              childAspectRatio: 2,
+              crossAxisCount: 2,
+              children: verticalItems)),
+          SliverToBoxAdapter(
+            child: Padding(
+              padding: const EdgeInsets.only(top: 24),
+              child: Center(
+                child: Text("Horizontal lists",
+                  style: Theme.of(context).textTheme.headlineMedium)))),
+          SliverPadding(
+            padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 16),
+            sliver: SliverGrid.count(
+              childAspectRatio: 2,
+              crossAxisCount: 2,
+              children: horizontalItems)),
+          SliverToBoxAdapter(
+            child: Padding(
+              padding: const EdgeInsets.only(top: 24),
+              child: Center(
+                child: Text("Other examples",
+                  style: Theme.of(context).textTheme.headlineMedium)))),
+          SliverPadding(
+            padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 16),
+            sliver: SliverGrid.count(
+              childAspectRatio: 2,
+              crossAxisCount: 2,
+              children: otherItems)),
+        ]));
+  }
+
+  Widget _buildItem(BuildContext context, _ExampleType exampleType, {
+    required String title,
+    bool reverse = false,
+    required AxisDirection headerDirection,
+    bool primary = false,
+  }) {
+    Widget page;
+    switch (exampleType) {
+      case _ExampleType.vertical:
+        page = ExampleVertical(
+          title: title, reverse: reverse, headerDirection: headerDirection);
+        break;
+      case _ExampleType.horizontal:
+        page = ExampleHorizontal(
+          title: title, reverse: reverse, headerDirection: headerDirection);
+        break;
+    }
+    return _buildButton(context, title: title, page: page);
+  }
+
+  Widget _buildButton(BuildContext context, {
+    bool primary = false,
+    required String title,
+    required Widget page,
+  }) {
+    var label = Text(title,
+      textAlign: TextAlign.center,
+      style: TextStyle(
+        inherit: true,
+        fontSize: Theme.of(context).textTheme.titleMedium?.fontSize));
+    var buttonStyle = primary
+      ? null
+      : ElevatedButton.styleFrom(
+          foregroundColor: Theme.of(context).colorScheme.onSecondary,
+          backgroundColor: Theme.of(context).colorScheme.secondary);
+    return Container(
+      padding: const EdgeInsets.all(16),
+      child: ElevatedButton(
+        style: buttonStyle,
+        onPressed: () => Navigator.of(context)
+          .push(MaterialPageRoute<void>(builder: (_) => page)),
+        child: label));
+  }
+}
+
+class ExampleApp extends StatelessWidget {
+  const ExampleApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Sticky Headers example',
+      theme: ThemeData(
+        colorScheme:
+          ColorScheme.fromSeed(seedColor: const Color(0xff3366cc))),
+      home: const MainPage(),
+    );
+  }
+}
+
+void main() {
+  runApp(const ExampleApp());
+}
diff --git a/lib/generated/l10n/zulip_localizations.dart b/lib/generated/l10n/zulip_localizations.dart
index 6ff41633fd..3cbd917563 100644
--- a/lib/generated/l10n/zulip_localizations.dart
+++ b/lib/generated/l10n/zulip_localizations.dart
@@ -189,6 +189,12 @@ abstract class ZulipLocalizations {
   /// **'Send direct message'**
   String get profileButtonSendDirectMessage;
 
+  /// Message that appears on the user profile page when the profile cannot be shown.
+  ///
+  /// In en, this message translates to:
+  /// **'Could not show user profile.'**
+  String get errorCouldNotShowUserProfile;
+
   /// Title for dialog asking the user to grant additional permissions.
   ///
   /// In en, this message translates to:
@@ -237,6 +243,30 @@ abstract class ZulipLocalizations {
   /// **'Unfollow topic'**
   String get actionSheetOptionUnfollowTopic;
 
+  /// Label for the 'Mark as resolved' button on the topic action sheet.
+  ///
+  /// In en, this message translates to:
+  /// **'Mark as resolved'**
+  String get actionSheetOptionResolveTopic;
+
+  /// Label for the 'Mark as unresolved' button on the topic action sheet.
+  ///
+  /// In en, this message translates to:
+  /// **'Mark as unresolved'**
+  String get actionSheetOptionUnresolveTopic;
+
+  /// Error title when marking a topic as resolved failed.
+  ///
+  /// In en, this message translates to:
+  /// **'Failed to mark topic as resolved'**
+  String get errorResolveTopicFailedTitle;
+
+  /// Error title when marking a topic as unresolved failed.
+  ///
+  /// In en, this message translates to:
+  /// **'Failed to mark topic as unresolved'**
+  String get errorUnresolveTopicFailedTitle;
+
   /// Label for copy message text button on action sheet.
   ///
   /// In en, this message translates to:
@@ -321,6 +351,12 @@ abstract class ZulipLocalizations {
   /// **'Failed to upload file: {filename}'**
   String errorFailedToUploadFileTitle(String filename);
 
+  /// The name of a file, and its size in mebibytes.
+  ///
+  /// In en, this message translates to:
+  /// **'{filename}: {size} MiB'**
+  String filenameAndSizeInMiB(String filename, String size);
+
   /// Error message when attached files are too large in size.
   ///
   /// In en, this message translates to:
@@ -405,6 +441,18 @@ abstract class ZulipLocalizations {
   /// **'Error handling a Zulip event from {serverUrl}; will retry.\n\nError: {error}\n\nEvent: {event}'**
   String errorHandlingEventDetails(String serverUrl, String error, String event);
 
+  /// Error title when opening a link failed.
+  ///
+  /// In en, this message translates to:
+  /// **'Unable to open link'**
+  String get errorCouldNotOpenLinkTitle;
+
+  /// Error message when opening a link failed.
+  ///
+  /// In en, this message translates to:
+  /// **'Link could not be opened: {url}'**
+  String errorCouldNotOpenLink(String url);
+
   /// Error message when muting a topic failed.
   ///
   /// In en, this message translates to:
@@ -535,7 +583,7 @@ abstract class ZulipLocalizations {
   ///
   /// In en, this message translates to:
   /// **'(unknown channel)'**
-  String get composeBoxUnknownChannelName;
+  String get unknownChannelName;
 
   /// Hint text for topic input widget in compose box.
   ///
@@ -549,18 +597,36 @@ abstract class ZulipLocalizations {
   /// **'Uploading {filename}…'**
   String composeBoxUploadingFilename(String filename);
 
+  /// Placeholder in compose box showing the quoted message is currently loading.
+  ///
+  /// In en, this message translates to:
+  /// **'(loading message {messageId})'**
+  String composeBoxLoadingMessage(int messageId);
+
   /// Name placeholder to use for a user when we don't know their name.
   ///
   /// In en, this message translates to:
   /// **'(unknown user)'**
   String get unknownUserName;
 
+  /// Message list page title for a DM group that only includes yourself.
+  ///
+  /// In en, this message translates to:
+  /// **'DMs with yourself'**
+  String get dmsWithYourselfPageTitle;
+
   /// Message list recipient header for a DM group with others.
   ///
   /// In en, this message translates to:
   /// **'You and {others}'**
   String messageListGroupYouAndOthers(String others);
 
+  /// Message list page title for a DM group with others.
+  ///
+  /// In en, this message translates to:
+  /// **'DMs with {others}'**
+  String dmsWithOthersPageTitle(String others);
+
   /// Message list recipient header for a DM group that only includes yourself.
   ///
   /// In en, this message translates to:
@@ -633,6 +699,18 @@ abstract class ZulipLocalizations {
   /// **'Copy link'**
   String get lightboxCopyLinkTooltip;
 
+  /// The current playback position of the video playing in the lightbox.
+  ///
+  /// In en, this message translates to:
+  /// **'Current position'**
+  String get lightboxVideoCurrentPosition;
+
+  /// The total duration of the video playing in the lightbox.
+  ///
+  /// In en, this message translates to:
+  /// **'Video duration'**
+  String get lightboxVideoDuration;
+
   /// Title for login page.
   ///
   /// In en, this message translates to:
@@ -663,11 +741,11 @@ abstract class ZulipLocalizations {
   /// **'Add an account'**
   String get loginAddAnAccountPageTitle;
 
-  /// Input label in login page for Zulip server URL entry.
+  /// Label in login page for Zulip server URL entry.
   ///
   /// In en, this message translates to:
   /// **'Your Zulip server URL'**
-  String get loginServerUrlInputLabel;
+  String get loginServerUrlLabel;
 
   /// Icon label for button to hide password in input form.
   ///
@@ -891,6 +969,12 @@ abstract class ZulipLocalizations {
   /// **'Direct messages'**
   String get recentDmConversationsPageTitle;
 
+  /// Heading for direct messages section on the 'Inbox' message view.
+  ///
+  /// In en, this message translates to:
+  /// **'Direct messages'**
+  String get recentDmConversationsSectionHeader;
+
   /// Page title for the 'Combined feed' message view.
   ///
   /// In en, this message translates to:
@@ -933,12 +1017,36 @@ abstract class ZulipLocalizations {
   /// **'{senderFullName} to you and {numOthers, plural, =1{1 other} other{{numOthers} others}}'**
   String notifGroupDmConversationLabel(String senderFullName, int numOthers);
 
+  /// Label for the list of pinned subscribed channels.
+  ///
+  /// In en, this message translates to:
+  /// **'Pinned'**
+  String get pinnedSubscriptionsLabel;
+
+  /// Label for the list of unpinned subscribed channels.
+  ///
+  /// In en, this message translates to:
+  /// **'Unpinned'**
+  String get unpinnedSubscriptionsLabel;
+
+  /// Text to display on subscribed-channels page when there are no subscribed channels.
+  ///
+  /// In en, this message translates to:
+  /// **'No channels found'**
+  String get subscriptionListNoChannels;
+
   /// Display name for the user themself, to show after replying in an Android notification
   ///
   /// In en, this message translates to:
   /// **'You'**
   String get notifSelfUser;
 
+  /// Display name for the user themself, to show on an emoji reaction added by the user.
+  ///
+  /// In en, this message translates to:
+  /// **'You'**
+  String get reactedEmojiSelfUser;
+
   /// Text to display when there is one user typing.
   ///
   /// In en, this message translates to:
@@ -957,6 +1065,60 @@ abstract class ZulipLocalizations {
   /// **'Several people are typing…'**
   String get manyPeopleTyping;
 
+  /// Text for "@all" wildcard-mention autocomplete option when writing a channel or DM message.
+  ///
+  /// In en, this message translates to:
+  /// **'all'**
+  String get wildcardMentionAll;
+
+  /// Text for "@everyone" wildcard-mention autocomplete option when writing a channel or DM message.
+  ///
+  /// In en, this message translates to:
+  /// **'everyone'**
+  String get wildcardMentionEveryone;
+
+  /// Text for "@channel" wildcard-mention autocomplete option when writing a channel message.
+  ///
+  /// In en, this message translates to:
+  /// **'channel'**
+  String get wildcardMentionChannel;
+
+  /// Text for "@stream" wildcard-mention autocomplete option when writing a channel message in older servers.
+  ///
+  /// In en, this message translates to:
+  /// **'stream'**
+  String get wildcardMentionStream;
+
+  /// Text for "@topic" wildcard-mention autocomplete option when writing a channel message.
+  ///
+  /// In en, this message translates to:
+  /// **'topic'**
+  String get wildcardMentionTopic;
+
+  /// Description for "@all", "@everyone", "@channel", and "@stream" wildcard-mention autocomplete options when writing a channel message.
+  ///
+  /// In en, this message translates to:
+  /// **'Notify channel'**
+  String get wildcardMentionChannelDescription;
+
+  /// Description for "@all", "@everyone", and "@stream" wildcard-mention autocomplete options when writing a channel message in older servers.
+  ///
+  /// In en, this message translates to:
+  /// **'Notify stream'**
+  String get wildcardMentionStreamDescription;
+
+  /// Description for "@all" and "@everyone" wildcard-mention autocomplete options when writing a DM message.
+  ///
+  /// In en, this message translates to:
+  /// **'Notify recipients'**
+  String get wildcardMentionAllDmDescription;
+
+  /// Description for "@topic" wildcard-mention autocomplete options when writing a channel message.
+  ///
+  /// In en, this message translates to:
+  /// **'Notify topic'**
+  String get wildcardMentionTopicDescription;
+
   /// Label for an edited message. (Use ALL CAPS for cased alphabets: Latin, Greek, Cyrillic, etc.)
   ///
   /// In en, this message translates to:
@@ -969,6 +1131,12 @@ abstract class ZulipLocalizations {
   /// **'MOVED'**
   String get messageIsMovedLabel;
 
+  /// The list of people who voted for a poll option, wrapped in parentheses.
+  ///
+  /// In en, this message translates to:
+  /// **'({voterNames})'**
+  String pollVoterNames(String voterNames);
+
   /// Text to display for a poll when the question is missing
   ///
   /// In en, this message translates to:
@@ -1016,6 +1184,30 @@ abstract class ZulipLocalizations {
   /// In en, this message translates to:
   /// **'Search emoji'**
   String get emojiPickerSearchEmoji;
+
+  /// Text to show at the start of a message list if there are no earlier messages.
+  ///
+  /// In en, this message translates to:
+  /// **'No earlier messages'**
+  String get noEarlierMessages;
+
+  /// Tooltip for button to scroll to bottom.
+  ///
+  /// In en, this message translates to:
+  /// **'Scroll to bottom'**
+  String get scrollToBottomTooltip;
+
+  /// Placeholder to show in place of the app version when it is unknown.
+  ///
+  /// In en, this message translates to:
+  /// **'(…)'**
+  String get appVersionUnknownPlaceholder;
+
+  /// The name of Zulip. This should be either 'Zulip' or a transliteration.
+  ///
+  /// In en, this message translates to:
+  /// **'Zulip'**
+  String get zulipAppTitle;
 }
 
 class _ZulipLocalizationsDelegate extends LocalizationsDelegate<ZulipLocalizations> {
diff --git a/lib/generated/l10n/zulip_localizations_ar.dart b/lib/generated/l10n/zulip_localizations_ar.dart
index 542b85031b..0304fd3e6f 100644
--- a/lib/generated/l10n/zulip_localizations_ar.dart
+++ b/lib/generated/l10n/zulip_localizations_ar.dart
@@ -52,6 +52,9 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   @override
   String get profileButtonSendDirectMessage => 'Send direct message';
 
+  @override
+  String get errorCouldNotShowUserProfile => 'Could not show user profile.';
+
   @override
   String get permissionsNeededTitle => 'Permissions needed';
 
@@ -76,6 +79,18 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   @override
   String get actionSheetOptionUnfollowTopic => 'Unfollow topic';
 
+  @override
+  String get actionSheetOptionResolveTopic => 'Mark as resolved';
+
+  @override
+  String get actionSheetOptionUnresolveTopic => 'Mark as unresolved';
+
+  @override
+  String get errorResolveTopicFailedTitle => 'Failed to mark topic as resolved';
+
+  @override
+  String get errorUnresolveTopicFailedTitle => 'Failed to mark topic as unresolved';
+
   @override
   String get actionSheetOptionCopyMessageText => 'Copy message text';
 
@@ -122,6 +137,11 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
     return 'Failed to upload file: $filename';
   }
 
+  @override
+  String filenameAndSizeInMiB(String filename, String size) {
+    return '$filename: $size MiB';
+  }
+
   @override
   String errorFilesTooLarge(int num, int maxFileUploadSizeMib, String listMessage) {
     String _temp0 = intl.Intl.pluralLogic(
@@ -188,6 +208,14 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
     return 'Error handling a Zulip event from $serverUrl; will retry.\n\nError: $error\n\nEvent: $event';
   }
 
+  @override
+  String get errorCouldNotOpenLinkTitle => 'Unable to open link';
+
+  @override
+  String errorCouldNotOpenLink(String url) {
+    return 'Link could not be opened: $url';
+  }
+
   @override
   String get errorMuteTopicFailed => 'Failed to mute topic';
 
@@ -256,7 +284,7 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   String get composeBoxSendTooltip => 'Send';
 
   @override
-  String get composeBoxUnknownChannelName => '(unknown channel)';
+  String get unknownChannelName => '(unknown channel)';
 
   @override
   String get composeBoxTopicHintText => 'Topic';
@@ -266,14 +294,27 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
     return 'Uploading $filename…';
   }
 
+  @override
+  String composeBoxLoadingMessage(int messageId) {
+    return '(loading message $messageId)';
+  }
+
   @override
   String get unknownUserName => '(unknown user)';
 
+  @override
+  String get dmsWithYourselfPageTitle => 'DMs with yourself';
+
   @override
   String messageListGroupYouAndOthers(String others) {
     return 'You and $others';
   }
 
+  @override
+  String dmsWithOthersPageTitle(String others) {
+    return 'DMs with $others';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'You with yourself';
 
@@ -310,6 +351,12 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   @override
   String get lightboxCopyLinkTooltip => 'Copy link';
 
+  @override
+  String get lightboxVideoCurrentPosition => 'Current position';
+
+  @override
+  String get lightboxVideoDuration => 'Video duration';
+
   @override
   String get loginPageTitle => 'Log in';
 
@@ -328,7 +375,7 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   String get loginAddAnAccountPageTitle => 'Add an account';
 
   @override
-  String get loginServerUrlInputLabel => 'Your Zulip server URL';
+  String get loginServerUrlLabel => 'Your Zulip server URL';
 
   @override
   String get loginHidePassword => 'Hide password';
@@ -463,6 +510,9 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   @override
   String get recentDmConversationsPageTitle => 'Direct messages';
 
+  @override
+  String get recentDmConversationsSectionHeader => 'Direct messages';
+
   @override
   String get combinedFeedPageTitle => 'Combined feed';
 
@@ -492,9 +542,21 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
     return '$senderFullName to you and $_temp0';
   }
 
+  @override
+  String get pinnedSubscriptionsLabel => 'Pinned';
+
+  @override
+  String get unpinnedSubscriptionsLabel => 'Unpinned';
+
+  @override
+  String get subscriptionListNoChannels => 'No channels found';
+
   @override
   String get notifSelfUser => 'You';
 
+  @override
+  String get reactedEmojiSelfUser => 'You';
+
   @override
   String onePersonTyping(String typist) {
     return '$typist is typing…';
@@ -508,12 +570,44 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   @override
   String get manyPeopleTyping => 'Several people are typing…';
 
+  @override
+  String get wildcardMentionAll => 'الجميع';
+
+  @override
+  String get wildcardMentionEveryone => 'الكل';
+
+  @override
+  String get wildcardMentionChannel => 'القناة';
+
+  @override
+  String get wildcardMentionStream => 'الدفق';
+
+  @override
+  String get wildcardMentionTopic => 'الموضوع';
+
+  @override
+  String get wildcardMentionChannelDescription => 'إخطار القناة';
+
+  @override
+  String get wildcardMentionStreamDescription => 'إخطار الدفق';
+
+  @override
+  String get wildcardMentionAllDmDescription => 'إخطار المستلمين';
+
+  @override
+  String get wildcardMentionTopicDescription => 'إخطار الموضوع';
+
   @override
   String get messageIsEditedLabel => 'EDITED';
 
   @override
   String get messageIsMovedLabel => 'MOVED';
 
+  @override
+  String pollVoterNames(String voterNames) {
+    return '($voterNames)';
+  }
+
   @override
   String get pollWidgetQuestionMissing => 'No question.';
 
@@ -537,4 +631,16 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get noEarlierMessages => 'No earlier messages';
+
+  @override
+  String get scrollToBottomTooltip => 'Scroll to bottom';
+
+  @override
+  String get appVersionUnknownPlaceholder => '(…)';
+
+  @override
+  String get zulipAppTitle => 'Zulip';
 }
diff --git a/lib/generated/l10n/zulip_localizations_en.dart b/lib/generated/l10n/zulip_localizations_en.dart
index b6bc9f72e7..7af8cd7bab 100644
--- a/lib/generated/l10n/zulip_localizations_en.dart
+++ b/lib/generated/l10n/zulip_localizations_en.dart
@@ -52,6 +52,9 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   @override
   String get profileButtonSendDirectMessage => 'Send direct message';
 
+  @override
+  String get errorCouldNotShowUserProfile => 'Could not show user profile.';
+
   @override
   String get permissionsNeededTitle => 'Permissions needed';
 
@@ -76,6 +79,18 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   @override
   String get actionSheetOptionUnfollowTopic => 'Unfollow topic';
 
+  @override
+  String get actionSheetOptionResolveTopic => 'Mark as resolved';
+
+  @override
+  String get actionSheetOptionUnresolveTopic => 'Mark as unresolved';
+
+  @override
+  String get errorResolveTopicFailedTitle => 'Failed to mark topic as resolved';
+
+  @override
+  String get errorUnresolveTopicFailedTitle => 'Failed to mark topic as unresolved';
+
   @override
   String get actionSheetOptionCopyMessageText => 'Copy message text';
 
@@ -122,6 +137,11 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
     return 'Failed to upload file: $filename';
   }
 
+  @override
+  String filenameAndSizeInMiB(String filename, String size) {
+    return '$filename: $size MiB';
+  }
+
   @override
   String errorFilesTooLarge(int num, int maxFileUploadSizeMib, String listMessage) {
     String _temp0 = intl.Intl.pluralLogic(
@@ -188,6 +208,14 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
     return 'Error handling a Zulip event from $serverUrl; will retry.\n\nError: $error\n\nEvent: $event';
   }
 
+  @override
+  String get errorCouldNotOpenLinkTitle => 'Unable to open link';
+
+  @override
+  String errorCouldNotOpenLink(String url) {
+    return 'Link could not be opened: $url';
+  }
+
   @override
   String get errorMuteTopicFailed => 'Failed to mute topic';
 
@@ -256,7 +284,7 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   String get composeBoxSendTooltip => 'Send';
 
   @override
-  String get composeBoxUnknownChannelName => '(unknown channel)';
+  String get unknownChannelName => '(unknown channel)';
 
   @override
   String get composeBoxTopicHintText => 'Topic';
@@ -266,14 +294,27 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
     return 'Uploading $filename…';
   }
 
+  @override
+  String composeBoxLoadingMessage(int messageId) {
+    return '(loading message $messageId)';
+  }
+
   @override
   String get unknownUserName => '(unknown user)';
 
+  @override
+  String get dmsWithYourselfPageTitle => 'DMs with yourself';
+
   @override
   String messageListGroupYouAndOthers(String others) {
     return 'You and $others';
   }
 
+  @override
+  String dmsWithOthersPageTitle(String others) {
+    return 'DMs with $others';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'You with yourself';
 
@@ -310,6 +351,12 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   @override
   String get lightboxCopyLinkTooltip => 'Copy link';
 
+  @override
+  String get lightboxVideoCurrentPosition => 'Current position';
+
+  @override
+  String get lightboxVideoDuration => 'Video duration';
+
   @override
   String get loginPageTitle => 'Log in';
 
@@ -328,7 +375,7 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   String get loginAddAnAccountPageTitle => 'Add an account';
 
   @override
-  String get loginServerUrlInputLabel => 'Your Zulip server URL';
+  String get loginServerUrlLabel => 'Your Zulip server URL';
 
   @override
   String get loginHidePassword => 'Hide password';
@@ -463,6 +510,9 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   @override
   String get recentDmConversationsPageTitle => 'Direct messages';
 
+  @override
+  String get recentDmConversationsSectionHeader => 'Direct messages';
+
   @override
   String get combinedFeedPageTitle => 'Combined feed';
 
@@ -492,9 +542,21 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
     return '$senderFullName to you and $_temp0';
   }
 
+  @override
+  String get pinnedSubscriptionsLabel => 'Pinned';
+
+  @override
+  String get unpinnedSubscriptionsLabel => 'Unpinned';
+
+  @override
+  String get subscriptionListNoChannels => 'No channels found';
+
   @override
   String get notifSelfUser => 'You';
 
+  @override
+  String get reactedEmojiSelfUser => 'You';
+
   @override
   String onePersonTyping(String typist) {
     return '$typist is typing…';
@@ -508,12 +570,44 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   @override
   String get manyPeopleTyping => 'Several people are typing…';
 
+  @override
+  String get wildcardMentionAll => 'all';
+
+  @override
+  String get wildcardMentionEveryone => 'everyone';
+
+  @override
+  String get wildcardMentionChannel => 'channel';
+
+  @override
+  String get wildcardMentionStream => 'stream';
+
+  @override
+  String get wildcardMentionTopic => 'topic';
+
+  @override
+  String get wildcardMentionChannelDescription => 'Notify channel';
+
+  @override
+  String get wildcardMentionStreamDescription => 'Notify stream';
+
+  @override
+  String get wildcardMentionAllDmDescription => 'Notify recipients';
+
+  @override
+  String get wildcardMentionTopicDescription => 'Notify topic';
+
   @override
   String get messageIsEditedLabel => 'EDITED';
 
   @override
   String get messageIsMovedLabel => 'MOVED';
 
+  @override
+  String pollVoterNames(String voterNames) {
+    return '($voterNames)';
+  }
+
   @override
   String get pollWidgetQuestionMissing => 'No question.';
 
@@ -537,4 +631,16 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get noEarlierMessages => 'No earlier messages';
+
+  @override
+  String get scrollToBottomTooltip => 'Scroll to bottom';
+
+  @override
+  String get appVersionUnknownPlaceholder => '(…)';
+
+  @override
+  String get zulipAppTitle => 'Zulip';
 }
diff --git a/lib/generated/l10n/zulip_localizations_ja.dart b/lib/generated/l10n/zulip_localizations_ja.dart
index 7adbc9ae8a..6ac34645e2 100644
--- a/lib/generated/l10n/zulip_localizations_ja.dart
+++ b/lib/generated/l10n/zulip_localizations_ja.dart
@@ -52,6 +52,9 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   @override
   String get profileButtonSendDirectMessage => 'ダイレクトメッセージを送信';
 
+  @override
+  String get errorCouldNotShowUserProfile => 'Could not show user profile.';
+
   @override
   String get permissionsNeededTitle => 'Permissions needed';
 
@@ -76,6 +79,18 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   @override
   String get actionSheetOptionUnfollowTopic => 'Unfollow topic';
 
+  @override
+  String get actionSheetOptionResolveTopic => 'Mark as resolved';
+
+  @override
+  String get actionSheetOptionUnresolveTopic => 'Mark as unresolved';
+
+  @override
+  String get errorResolveTopicFailedTitle => 'Failed to mark topic as resolved';
+
+  @override
+  String get errorUnresolveTopicFailedTitle => 'Failed to mark topic as unresolved';
+
   @override
   String get actionSheetOptionCopyMessageText => 'Copy message text';
 
@@ -122,6 +137,11 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
     return 'Failed to upload file: $filename';
   }
 
+  @override
+  String filenameAndSizeInMiB(String filename, String size) {
+    return '$filename: $size MiB';
+  }
+
   @override
   String errorFilesTooLarge(int num, int maxFileUploadSizeMib, String listMessage) {
     String _temp0 = intl.Intl.pluralLogic(
@@ -188,6 +208,14 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
     return 'Error handling a Zulip event from $serverUrl; will retry.\n\nError: $error\n\nEvent: $event';
   }
 
+  @override
+  String get errorCouldNotOpenLinkTitle => 'Unable to open link';
+
+  @override
+  String errorCouldNotOpenLink(String url) {
+    return 'Link could not be opened: $url';
+  }
+
   @override
   String get errorMuteTopicFailed => 'Failed to mute topic';
 
@@ -256,7 +284,7 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   String get composeBoxSendTooltip => 'Send';
 
   @override
-  String get composeBoxUnknownChannelName => '(unknown channel)';
+  String get unknownChannelName => '(unknown channel)';
 
   @override
   String get composeBoxTopicHintText => 'Topic';
@@ -266,14 +294,27 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
     return 'Uploading $filename…';
   }
 
+  @override
+  String composeBoxLoadingMessage(int messageId) {
+    return '(loading message $messageId)';
+  }
+
   @override
   String get unknownUserName => '(unknown user)';
 
+  @override
+  String get dmsWithYourselfPageTitle => 'DMs with yourself';
+
   @override
   String messageListGroupYouAndOthers(String others) {
     return 'You and $others';
   }
 
+  @override
+  String dmsWithOthersPageTitle(String others) {
+    return 'DMs with $others';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'You with yourself';
 
@@ -310,6 +351,12 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   @override
   String get lightboxCopyLinkTooltip => 'Copy link';
 
+  @override
+  String get lightboxVideoCurrentPosition => 'Current position';
+
+  @override
+  String get lightboxVideoDuration => 'Video duration';
+
   @override
   String get loginPageTitle => 'Log in';
 
@@ -328,7 +375,7 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   String get loginAddAnAccountPageTitle => 'Add an account';
 
   @override
-  String get loginServerUrlInputLabel => 'Your Zulip server URL';
+  String get loginServerUrlLabel => 'Your Zulip server URL';
 
   @override
   String get loginHidePassword => 'Hide password';
@@ -463,6 +510,9 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   @override
   String get recentDmConversationsPageTitle => 'Direct messages';
 
+  @override
+  String get recentDmConversationsSectionHeader => 'Direct messages';
+
   @override
   String get combinedFeedPageTitle => 'Combined feed';
 
@@ -492,9 +542,21 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
     return '$senderFullName to you and $_temp0';
   }
 
+  @override
+  String get pinnedSubscriptionsLabel => 'Pinned';
+
+  @override
+  String get unpinnedSubscriptionsLabel => 'Unpinned';
+
+  @override
+  String get subscriptionListNoChannels => 'No channels found';
+
   @override
   String get notifSelfUser => 'You';
 
+  @override
+  String get reactedEmojiSelfUser => 'You';
+
   @override
   String onePersonTyping(String typist) {
     return '$typist is typing…';
@@ -508,12 +570,44 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   @override
   String get manyPeopleTyping => 'Several people are typing…';
 
+  @override
+  String get wildcardMentionAll => 'all';
+
+  @override
+  String get wildcardMentionEveryone => 'everyone';
+
+  @override
+  String get wildcardMentionChannel => 'channel';
+
+  @override
+  String get wildcardMentionStream => 'stream';
+
+  @override
+  String get wildcardMentionTopic => 'topic';
+
+  @override
+  String get wildcardMentionChannelDescription => 'Notify channel';
+
+  @override
+  String get wildcardMentionStreamDescription => 'Notify stream';
+
+  @override
+  String get wildcardMentionAllDmDescription => 'Notify recipients';
+
+  @override
+  String get wildcardMentionTopicDescription => 'Notify topic';
+
   @override
   String get messageIsEditedLabel => 'EDITED';
 
   @override
   String get messageIsMovedLabel => 'MOVED';
 
+  @override
+  String pollVoterNames(String voterNames) {
+    return '($voterNames)';
+  }
+
   @override
   String get pollWidgetQuestionMissing => 'No question.';
 
@@ -537,4 +631,16 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get noEarlierMessages => 'No earlier messages';
+
+  @override
+  String get scrollToBottomTooltip => 'Scroll to bottom';
+
+  @override
+  String get appVersionUnknownPlaceholder => '(…)';
+
+  @override
+  String get zulipAppTitle => 'Zulip';
 }
diff --git a/lib/generated/l10n/zulip_localizations_nb.dart b/lib/generated/l10n/zulip_localizations_nb.dart
index 99c545f98e..b3360e9f62 100644
--- a/lib/generated/l10n/zulip_localizations_nb.dart
+++ b/lib/generated/l10n/zulip_localizations_nb.dart
@@ -9,13 +9,13 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   ZulipLocalizationsNb([String locale = 'nb']) : super(locale);
 
   @override
-  String get aboutPageTitle => 'About Zulip';
+  String get aboutPageTitle => 'Om Zulip';
 
   @override
-  String get aboutPageAppVersion => 'App version';
+  String get aboutPageAppVersion => 'App versjon';
 
   @override
-  String get aboutPageOpenSourceLicenses => 'Open-source licenses';
+  String get aboutPageOpenSourceLicenses => 'Lisenser for åpen kildekode';
 
   @override
   String get aboutPageTapToView => 'Tap to view';
@@ -52,6 +52,9 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   @override
   String get profileButtonSendDirectMessage => 'Send direct message';
 
+  @override
+  String get errorCouldNotShowUserProfile => 'Could not show user profile.';
+
   @override
   String get permissionsNeededTitle => 'Permissions needed';
 
@@ -76,6 +79,18 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   @override
   String get actionSheetOptionUnfollowTopic => 'Unfollow topic';
 
+  @override
+  String get actionSheetOptionResolveTopic => 'Mark as resolved';
+
+  @override
+  String get actionSheetOptionUnresolveTopic => 'Mark as unresolved';
+
+  @override
+  String get errorResolveTopicFailedTitle => 'Failed to mark topic as resolved';
+
+  @override
+  String get errorUnresolveTopicFailedTitle => 'Failed to mark topic as unresolved';
+
   @override
   String get actionSheetOptionCopyMessageText => 'Copy message text';
 
@@ -122,6 +137,11 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
     return 'Failed to upload file: $filename';
   }
 
+  @override
+  String filenameAndSizeInMiB(String filename, String size) {
+    return '$filename: $size MiB';
+  }
+
   @override
   String errorFilesTooLarge(int num, int maxFileUploadSizeMib, String listMessage) {
     String _temp0 = intl.Intl.pluralLogic(
@@ -188,6 +208,14 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
     return 'Error handling a Zulip event from $serverUrl; will retry.\n\nError: $error\n\nEvent: $event';
   }
 
+  @override
+  String get errorCouldNotOpenLinkTitle => 'Unable to open link';
+
+  @override
+  String errorCouldNotOpenLink(String url) {
+    return 'Link could not be opened: $url';
+  }
+
   @override
   String get errorMuteTopicFailed => 'Failed to mute topic';
 
@@ -256,7 +284,7 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   String get composeBoxSendTooltip => 'Send';
 
   @override
-  String get composeBoxUnknownChannelName => '(unknown channel)';
+  String get unknownChannelName => '(unknown channel)';
 
   @override
   String get composeBoxTopicHintText => 'Topic';
@@ -266,14 +294,27 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
     return 'Uploading $filename…';
   }
 
+  @override
+  String composeBoxLoadingMessage(int messageId) {
+    return '(loading message $messageId)';
+  }
+
   @override
   String get unknownUserName => '(unknown user)';
 
+  @override
+  String get dmsWithYourselfPageTitle => 'DMs with yourself';
+
   @override
   String messageListGroupYouAndOthers(String others) {
     return 'You and $others';
   }
 
+  @override
+  String dmsWithOthersPageTitle(String others) {
+    return 'DMs with $others';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'You with yourself';
 
@@ -310,6 +351,12 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   @override
   String get lightboxCopyLinkTooltip => 'Copy link';
 
+  @override
+  String get lightboxVideoCurrentPosition => 'Current position';
+
+  @override
+  String get lightboxVideoDuration => 'Video duration';
+
   @override
   String get loginPageTitle => 'Log in';
 
@@ -328,7 +375,7 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   String get loginAddAnAccountPageTitle => 'Add an account';
 
   @override
-  String get loginServerUrlInputLabel => 'Your Zulip server URL';
+  String get loginServerUrlLabel => 'Your Zulip server URL';
 
   @override
   String get loginHidePassword => 'Hide password';
@@ -463,6 +510,9 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   @override
   String get recentDmConversationsPageTitle => 'Direct messages';
 
+  @override
+  String get recentDmConversationsSectionHeader => 'Direct messages';
+
   @override
   String get combinedFeedPageTitle => 'Combined feed';
 
@@ -492,9 +542,21 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
     return '$senderFullName to you and $_temp0';
   }
 
+  @override
+  String get pinnedSubscriptionsLabel => 'Pinned';
+
+  @override
+  String get unpinnedSubscriptionsLabel => 'Unpinned';
+
+  @override
+  String get subscriptionListNoChannels => 'No channels found';
+
   @override
   String get notifSelfUser => 'You';
 
+  @override
+  String get reactedEmojiSelfUser => 'You';
+
   @override
   String onePersonTyping(String typist) {
     return '$typist is typing…';
@@ -508,12 +570,44 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   @override
   String get manyPeopleTyping => 'Several people are typing…';
 
+  @override
+  String get wildcardMentionAll => 'all';
+
+  @override
+  String get wildcardMentionEveryone => 'everyone';
+
+  @override
+  String get wildcardMentionChannel => 'channel';
+
+  @override
+  String get wildcardMentionStream => 'stream';
+
+  @override
+  String get wildcardMentionTopic => 'topic';
+
+  @override
+  String get wildcardMentionChannelDescription => 'Notify channel';
+
+  @override
+  String get wildcardMentionStreamDescription => 'Notify stream';
+
+  @override
+  String get wildcardMentionAllDmDescription => 'Notify recipients';
+
+  @override
+  String get wildcardMentionTopicDescription => 'Notify topic';
+
   @override
   String get messageIsEditedLabel => 'EDITED';
 
   @override
   String get messageIsMovedLabel => 'MOVED';
 
+  @override
+  String pollVoterNames(String voterNames) {
+    return '($voterNames)';
+  }
+
   @override
   String get pollWidgetQuestionMissing => 'No question.';
 
@@ -537,4 +631,16 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get noEarlierMessages => 'No earlier messages';
+
+  @override
+  String get scrollToBottomTooltip => 'Scroll to bottom';
+
+  @override
+  String get appVersionUnknownPlaceholder => '(…)';
+
+  @override
+  String get zulipAppTitle => 'Zulip';
 }
diff --git a/lib/generated/l10n/zulip_localizations_pl.dart b/lib/generated/l10n/zulip_localizations_pl.dart
index e7a05a58aa..22a56e5a0c 100644
--- a/lib/generated/l10n/zulip_localizations_pl.dart
+++ b/lib/generated/l10n/zulip_localizations_pl.dart
@@ -52,6 +52,9 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   @override
   String get profileButtonSendDirectMessage => 'Wyślij wiadomość bezpośrednią';
 
+  @override
+  String get errorCouldNotShowUserProfile => 'Nie udało się wyświetlić profilu.';
+
   @override
   String get permissionsNeededTitle => 'Wymagane uprawnienia';
 
@@ -76,6 +79,18 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   @override
   String get actionSheetOptionUnfollowTopic => 'Nie śledź wątku';
 
+  @override
+  String get actionSheetOptionResolveTopic => 'Oznacz jako rozwiązany';
+
+  @override
+  String get actionSheetOptionUnresolveTopic => 'Oznacz brak rozwiązania';
+
+  @override
+  String get errorResolveTopicFailedTitle => 'Nie udało się oznaczyć jako rozwiązany';
+
+  @override
+  String get errorUnresolveTopicFailedTitle => 'Nie udało się oznaczyć brak rozwiązania';
+
   @override
   String get actionSheetOptionCopyMessageText => 'Skopiuj tekst wiadomości';
 
@@ -122,6 +137,11 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
     return 'Nie udało się załadować pliku: $filename';
   }
 
+  @override
+  String filenameAndSizeInMiB(String filename, String size) {
+    return '$filename: $size MiB';
+  }
+
   @override
   String errorFilesTooLarge(int num, int maxFileUploadSizeMib, String listMessage) {
     String _temp0 = intl.Intl.pluralLogic(
@@ -188,6 +208,14 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
     return 'Błąd zdarzenia Zulip z $serverUrl; ponawiam.\n\nBłąd: $error\n\nZdarzenie: $event';
   }
 
+  @override
+  String get errorCouldNotOpenLinkTitle => 'Nie udało się otworzyć odnośnika';
+
+  @override
+  String errorCouldNotOpenLink(String url) {
+    return 'Nie można otworzyć: $url';
+  }
+
   @override
   String get errorMuteTopicFailed => 'Wyciszenie bez powodzenia';
 
@@ -256,7 +284,7 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   String get composeBoxSendTooltip => 'Wyślij';
 
   @override
-  String get composeBoxUnknownChannelName => '(nieznany kanał)';
+  String get unknownChannelName => '(nieznany kanał)';
 
   @override
   String get composeBoxTopicHintText => 'Wątek';
@@ -266,14 +294,27 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
     return 'Przekazywanie $filename…';
   }
 
+  @override
+  String composeBoxLoadingMessage(int messageId) {
+    return '(ładowanie wiadomości $messageId)';
+  }
+
   @override
   String get unknownUserName => '(nieznany użytkownik)';
 
+  @override
+  String get dmsWithYourselfPageTitle => 'DM do siebie';
+
   @override
   String messageListGroupYouAndOthers(String others) {
     return 'Ty i $others';
   }
 
+  @override
+  String dmsWithOthersPageTitle(String others) {
+    return 'DM z $others';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'Ty ze sobą';
 
@@ -310,6 +351,12 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   @override
   String get lightboxCopyLinkTooltip => 'Skopiuj odnośnik';
 
+  @override
+  String get lightboxVideoCurrentPosition => 'Obecna pozycja';
+
+  @override
+  String get lightboxVideoDuration => 'Długość wideo';
+
   @override
   String get loginPageTitle => 'Zaloguj';
 
@@ -328,7 +375,7 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   String get loginAddAnAccountPageTitle => 'Dodaj konto';
 
   @override
-  String get loginServerUrlInputLabel => 'URL serwera Zulip';
+  String get loginServerUrlLabel => 'URL serwera Zulip';
 
   @override
   String get loginHidePassword => 'Ukryj hasło';
@@ -463,6 +510,9 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   @override
   String get recentDmConversationsPageTitle => 'Wiadomości bezpośrednie';
 
+  @override
+  String get recentDmConversationsSectionHeader => 'Wiadomości bezpośrednie';
+
   @override
   String get combinedFeedPageTitle => 'Mieszany widok';
 
@@ -492,9 +542,21 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
     return '$senderFullName do ciebie i $_temp0';
   }
 
+  @override
+  String get pinnedSubscriptionsLabel => 'Przypięte';
+
+  @override
+  String get unpinnedSubscriptionsLabel => 'Odpięte';
+
+  @override
+  String get subscriptionListNoChannels => 'Nie odnaleziono kanałów';
+
   @override
   String get notifSelfUser => 'Ty';
 
+  @override
+  String get reactedEmojiSelfUser => 'Ty';
+
   @override
   String onePersonTyping(String typist) {
     return '$typist coś pisze…';
@@ -508,12 +570,44 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   @override
   String get manyPeopleTyping => 'Wielu ludzi coś pisze…';
 
+  @override
+  String get wildcardMentionAll => 'wszyscy';
+
+  @override
+  String get wildcardMentionEveryone => 'każdy';
+
+  @override
+  String get wildcardMentionChannel => 'kanał';
+
+  @override
+  String get wildcardMentionStream => 'strumień';
+
+  @override
+  String get wildcardMentionTopic => 'wątek';
+
+  @override
+  String get wildcardMentionChannelDescription => 'Powiadom w kanale';
+
+  @override
+  String get wildcardMentionStreamDescription => 'Powiadom w strumieniu';
+
+  @override
+  String get wildcardMentionAllDmDescription => 'Powiadom zainteresowanych';
+
+  @override
+  String get wildcardMentionTopicDescription => 'Powiadom w wątku';
+
   @override
   String get messageIsEditedLabel => 'ZMIENIONO';
 
   @override
   String get messageIsMovedLabel => 'PRZENIESIONO';
 
+  @override
+  String pollVoterNames(String voterNames) {
+    return '($voterNames)';
+  }
+
   @override
   String get pollWidgetQuestionMissing => 'Brak pytania.';
 
@@ -537,4 +631,16 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Szukaj emoji';
+
+  @override
+  String get noEarlierMessages => 'Brak historii';
+
+  @override
+  String get scrollToBottomTooltip => 'Przewiń do dołu';
+
+  @override
+  String get appVersionUnknownPlaceholder => '(…)';
+
+  @override
+  String get zulipAppTitle => 'Zulip';
 }
diff --git a/lib/generated/l10n/zulip_localizations_ru.dart b/lib/generated/l10n/zulip_localizations_ru.dart
index 2082984588..babbc976fd 100644
--- a/lib/generated/l10n/zulip_localizations_ru.dart
+++ b/lib/generated/l10n/zulip_localizations_ru.dart
@@ -52,6 +52,9 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   @override
   String get profileButtonSendDirectMessage => 'Отправить личное сообщение';
 
+  @override
+  String get errorCouldNotShowUserProfile => 'Could not show user profile.';
+
   @override
   String get permissionsNeededTitle => 'Требуются разрешения';
 
@@ -76,6 +79,18 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   @override
   String get actionSheetOptionUnfollowTopic => 'Не отслеживать тему';
 
+  @override
+  String get actionSheetOptionResolveTopic => 'Mark as resolved';
+
+  @override
+  String get actionSheetOptionUnresolveTopic => 'Mark as unresolved';
+
+  @override
+  String get errorResolveTopicFailedTitle => 'Failed to mark topic as resolved';
+
+  @override
+  String get errorUnresolveTopicFailedTitle => 'Failed to mark topic as unresolved';
+
   @override
   String get actionSheetOptionCopyMessageText => 'Скопировать текст сообщения';
 
@@ -122,6 +137,11 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
     return 'Не удалось загрузить файл: $filename';
   }
 
+  @override
+  String filenameAndSizeInMiB(String filename, String size) {
+    return '$filename: $size MiB';
+  }
+
   @override
   String errorFilesTooLarge(int num, int maxFileUploadSizeMib, String listMessage) {
     String _temp0 = intl.Intl.pluralLogic(
@@ -188,6 +208,14 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
     return 'Ошибка обработки события Zulip от $serverUrl; повторим попытку.\n\nОшибка: $error\n\nСобытие: $event';
   }
 
+  @override
+  String get errorCouldNotOpenLinkTitle => 'Unable to open link';
+
+  @override
+  String errorCouldNotOpenLink(String url) {
+    return 'Link could not be opened: $url';
+  }
+
   @override
   String get errorMuteTopicFailed => 'Не удалось отключить тему';
 
@@ -256,7 +284,7 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   String get composeBoxSendTooltip => 'Отправить';
 
   @override
-  String get composeBoxUnknownChannelName => '(неизвестный канал)';
+  String get unknownChannelName => '(unknown channel)';
 
   @override
   String get composeBoxTopicHintText => 'Тема';
@@ -266,14 +294,27 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
     return 'Загрузка $filename…';
   }
 
+  @override
+  String composeBoxLoadingMessage(int messageId) {
+    return '(loading message $messageId)';
+  }
+
   @override
   String get unknownUserName => '(неизвестный пользователь)';
 
+  @override
+  String get dmsWithYourselfPageTitle => 'DMs with yourself';
+
   @override
   String messageListGroupYouAndOthers(String others) {
     return 'Вы и $others';
   }
 
+  @override
+  String dmsWithOthersPageTitle(String others) {
+    return 'DMs with $others';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'Вы с собой';
 
@@ -310,6 +351,12 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   @override
   String get lightboxCopyLinkTooltip => 'Скопировать ссылку';
 
+  @override
+  String get lightboxVideoCurrentPosition => 'Current position';
+
+  @override
+  String get lightboxVideoDuration => 'Video duration';
+
   @override
   String get loginPageTitle => 'Вход в систему';
 
@@ -328,7 +375,7 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   String get loginAddAnAccountPageTitle => 'Добавление учетной записи';
 
   @override
-  String get loginServerUrlInputLabel => 'URL вашего сервера Zulip';
+  String get loginServerUrlLabel => 'URL вашего сервера Zulip';
 
   @override
   String get loginHidePassword => 'Скрыть пароль';
@@ -463,6 +510,9 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   @override
   String get recentDmConversationsPageTitle => 'Личные сообщения';
 
+  @override
+  String get recentDmConversationsSectionHeader => 'Direct messages';
+
   @override
   String get combinedFeedPageTitle => 'Объединенная лента';
 
@@ -492,9 +542,21 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
     return '$senderFullName вам и еще $_temp0';
   }
 
+  @override
+  String get pinnedSubscriptionsLabel => 'Pinned';
+
+  @override
+  String get unpinnedSubscriptionsLabel => 'Unpinned';
+
+  @override
+  String get subscriptionListNoChannels => 'No channels found';
+
   @override
   String get notifSelfUser => 'Вы';
 
+  @override
+  String get reactedEmojiSelfUser => 'You';
+
   @override
   String onePersonTyping(String typist) {
     return '$typist набирает сообщение…';
@@ -508,12 +570,44 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   @override
   String get manyPeopleTyping => 'Несколько человек набирают сообщения…';
 
+  @override
+  String get wildcardMentionAll => 'all';
+
+  @override
+  String get wildcardMentionEveryone => 'everyone';
+
+  @override
+  String get wildcardMentionChannel => 'channel';
+
+  @override
+  String get wildcardMentionStream => 'stream';
+
+  @override
+  String get wildcardMentionTopic => 'topic';
+
+  @override
+  String get wildcardMentionChannelDescription => 'Notify channel';
+
+  @override
+  String get wildcardMentionStreamDescription => 'Notify stream';
+
+  @override
+  String get wildcardMentionAllDmDescription => 'Notify recipients';
+
+  @override
+  String get wildcardMentionTopicDescription => 'Notify topic';
+
   @override
   String get messageIsEditedLabel => 'ИЗМЕНЕНО';
 
   @override
   String get messageIsMovedLabel => 'ПЕРЕМЕЩЕНО';
 
+  @override
+  String pollVoterNames(String voterNames) {
+    return '($voterNames)';
+  }
+
   @override
   String get pollWidgetQuestionMissing => 'Нет вопроса.';
 
@@ -537,4 +631,16 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Поиск эмодзи';
+
+  @override
+  String get noEarlierMessages => 'No earlier messages';
+
+  @override
+  String get scrollToBottomTooltip => 'Scroll to bottom';
+
+  @override
+  String get appVersionUnknownPlaceholder => '(…)';
+
+  @override
+  String get zulipAppTitle => 'Zulip';
 }
diff --git a/lib/generated/l10n/zulip_localizations_sk.dart b/lib/generated/l10n/zulip_localizations_sk.dart
index fabfa06eb4..964dbc29ad 100644
--- a/lib/generated/l10n/zulip_localizations_sk.dart
+++ b/lib/generated/l10n/zulip_localizations_sk.dart
@@ -52,6 +52,9 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   @override
   String get profileButtonSendDirectMessage => 'Poslať priamu správu';
 
+  @override
+  String get errorCouldNotShowUserProfile => 'Could not show user profile.';
+
   @override
   String get permissionsNeededTitle => 'Permissions needed';
 
@@ -76,6 +79,18 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   @override
   String get actionSheetOptionUnfollowTopic => 'Prestať sledovať tému';
 
+  @override
+  String get actionSheetOptionResolveTopic => 'Mark as resolved';
+
+  @override
+  String get actionSheetOptionUnresolveTopic => 'Mark as unresolved';
+
+  @override
+  String get errorResolveTopicFailedTitle => 'Failed to mark topic as resolved';
+
+  @override
+  String get errorUnresolveTopicFailedTitle => 'Failed to mark topic as unresolved';
+
   @override
   String get actionSheetOptionCopyMessageText => 'Skopírovať text správy';
 
@@ -122,6 +137,11 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
     return 'Nepodarilo sa nahrať súbor: $filename';
   }
 
+  @override
+  String filenameAndSizeInMiB(String filename, String size) {
+    return '$filename: $size MiB';
+  }
+
   @override
   String errorFilesTooLarge(int num, int maxFileUploadSizeMib, String listMessage) {
     String _temp0 = intl.Intl.pluralLogic(
@@ -188,6 +208,14 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
     return 'Chyba obsluhy Zulip udalosti na serveri $serverUrl; skúsim znovu.\n\nChyba: $error\n\nUdalosť: $event';
   }
 
+  @override
+  String get errorCouldNotOpenLinkTitle => 'Unable to open link';
+
+  @override
+  String errorCouldNotOpenLink(String url) {
+    return 'Link could not be opened: $url';
+  }
+
   @override
   String get errorMuteTopicFailed => 'Nepodarilo sa ztíšiť tému';
 
@@ -256,7 +284,7 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   String get composeBoxSendTooltip => 'Send';
 
   @override
-  String get composeBoxUnknownChannelName => '(unknown channel)';
+  String get unknownChannelName => '(unknown channel)';
 
   @override
   String get composeBoxTopicHintText => 'Topic';
@@ -266,14 +294,27 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
     return 'Uploading $filename…';
   }
 
+  @override
+  String composeBoxLoadingMessage(int messageId) {
+    return '(loading message $messageId)';
+  }
+
   @override
   String get unknownUserName => '(unknown user)';
 
+  @override
+  String get dmsWithYourselfPageTitle => 'DMs with yourself';
+
   @override
   String messageListGroupYouAndOthers(String others) {
     return 'You and $others';
   }
 
+  @override
+  String dmsWithOthersPageTitle(String others) {
+    return 'DMs with $others';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'You with yourself';
 
@@ -310,6 +351,12 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   @override
   String get lightboxCopyLinkTooltip => 'Skopírovať odkaz';
 
+  @override
+  String get lightboxVideoCurrentPosition => 'Current position';
+
+  @override
+  String get lightboxVideoDuration => 'Video duration';
+
   @override
   String get loginPageTitle => 'Prihlásiť sa';
 
@@ -328,7 +375,7 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   String get loginAddAnAccountPageTitle => 'Pridať účet';
 
   @override
-  String get loginServerUrlInputLabel => 'Adresa vášho Zulip servera';
+  String get loginServerUrlLabel => 'Adresa vášho Zulip servera';
 
   @override
   String get loginHidePassword => 'Skryť heslo';
@@ -463,6 +510,9 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   @override
   String get recentDmConversationsPageTitle => 'Priama správa';
 
+  @override
+  String get recentDmConversationsSectionHeader => 'Direct messages';
+
   @override
   String get combinedFeedPageTitle => 'Zlúčený kanál';
 
@@ -492,9 +542,21 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
     return '$senderFullName to you and $_temp0';
   }
 
+  @override
+  String get pinnedSubscriptionsLabel => 'Pinned';
+
+  @override
+  String get unpinnedSubscriptionsLabel => 'Unpinned';
+
+  @override
+  String get subscriptionListNoChannels => 'No channels found';
+
   @override
   String get notifSelfUser => 'Ty';
 
+  @override
+  String get reactedEmojiSelfUser => 'You';
+
   @override
   String onePersonTyping(String typist) {
     return '$typist píše…';
@@ -508,12 +570,44 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   @override
   String get manyPeopleTyping => 'Niekoľko ludí píše…';
 
+  @override
+  String get wildcardMentionAll => 'all';
+
+  @override
+  String get wildcardMentionEveryone => 'everyone';
+
+  @override
+  String get wildcardMentionChannel => 'channel';
+
+  @override
+  String get wildcardMentionStream => 'stream';
+
+  @override
+  String get wildcardMentionTopic => 'topic';
+
+  @override
+  String get wildcardMentionChannelDescription => 'Notify channel';
+
+  @override
+  String get wildcardMentionStreamDescription => 'Notify stream';
+
+  @override
+  String get wildcardMentionAllDmDescription => 'Notify recipients';
+
+  @override
+  String get wildcardMentionTopicDescription => 'Notify topic';
+
   @override
   String get messageIsEditedLabel => 'UPRAVENÉ';
 
   @override
   String get messageIsMovedLabel => 'PRESUNUTÉ';
 
+  @override
+  String pollVoterNames(String voterNames) {
+    return '($voterNames)';
+  }
+
   @override
   String get pollWidgetQuestionMissing => 'Bez otázky.';
 
@@ -537,4 +631,16 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Hľadať emotikon';
+
+  @override
+  String get noEarlierMessages => 'No earlier messages';
+
+  @override
+  String get scrollToBottomTooltip => 'Scroll to bottom';
+
+  @override
+  String get appVersionUnknownPlaceholder => '(…)';
+
+  @override
+  String get zulipAppTitle => 'Zulip';
 }
diff --git a/lib/host/android_notifications.g.dart b/lib/host/android_notifications.g.dart
index 54825750ca..7b53559e64 100644
--- a/lib/host/android_notifications.g.dart
+++ b/lib/host/android_notifications.g.dart
@@ -1,4 +1,4 @@
-// Autogenerated from Pigeon (v20.0.2), do not edit directly.
+// Autogenerated from Pigeon (v22.7.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import, no_leading_underscores_for_local_identifiers
 
@@ -256,7 +256,7 @@ class MessagingStyle {
 
   String? conversationTitle;
 
-  List<MessagingStyleMessage?> messages;
+  List<MessagingStyleMessage> messages;
 
   bool isGroupConversation;
 
@@ -274,7 +274,7 @@ class MessagingStyle {
     return MessagingStyle(
       user: result[0]! as Person,
       conversationTitle: result[1] as String?,
-      messages: (result[2] as List<Object?>?)!.cast<MessagingStyleMessage?>(),
+      messages: (result[2] as List<Object?>?)!.cast<MessagingStyleMessage>(),
       isGroupConversation: result[3]! as bool,
     );
   }
@@ -291,7 +291,7 @@ class Notification {
 
   String group;
 
-  Map<String?, String?> extras;
+  Map<String, String> extras;
 
   Object encode() {
     return <Object?>[
@@ -304,7 +304,7 @@ class Notification {
     result as List<Object?>;
     return Notification(
       group: result[0]! as String,
-      extras: (result[1] as Map<Object?, Object?>?)!.cast<String?, String?>(),
+      extras: (result[1] as Map<Object?, Object?>?)!.cast<String, String>(),
     );
   }
 }
@@ -390,34 +390,37 @@ class _PigeonCodec extends StandardMessageCodec {
   const _PigeonCodec();
   @override
   void writeValue(WriteBuffer buffer, Object? value) {
-    if (value is NotificationChannel) {
+    if (value is int) {
+      buffer.putUint8(4);
+      buffer.putInt64(value);
+    }    else if (value is NotificationChannel) {
       buffer.putUint8(129);
       writeValue(buffer, value.encode());
-    } else     if (value is AndroidIntent) {
+    }    else if (value is AndroidIntent) {
       buffer.putUint8(130);
       writeValue(buffer, value.encode());
-    } else     if (value is PendingIntent) {
+    }    else if (value is PendingIntent) {
       buffer.putUint8(131);
       writeValue(buffer, value.encode());
-    } else     if (value is InboxStyle) {
+    }    else if (value is InboxStyle) {
       buffer.putUint8(132);
       writeValue(buffer, value.encode());
-    } else     if (value is Person) {
+    }    else if (value is Person) {
       buffer.putUint8(133);
       writeValue(buffer, value.encode());
-    } else     if (value is MessagingStyleMessage) {
+    }    else if (value is MessagingStyleMessage) {
       buffer.putUint8(134);
       writeValue(buffer, value.encode());
-    } else     if (value is MessagingStyle) {
+    }    else if (value is MessagingStyle) {
       buffer.putUint8(135);
       writeValue(buffer, value.encode());
-    } else     if (value is Notification) {
+    }    else if (value is Notification) {
       buffer.putUint8(136);
       writeValue(buffer, value.encode());
-    } else     if (value is StatusBarNotification) {
+    }    else if (value is StatusBarNotification) {
       buffer.putUint8(137);
       writeValue(buffer, value.encode());
-    } else     if (value is StoredNotificationSound) {
+    }    else if (value is StoredNotificationSound) {
       buffer.putUint8(138);
       writeValue(buffer, value.encode());
     } else {
@@ -459,33 +462,33 @@ class AndroidNotificationHostApi {
   /// available for dependency injection.  If it is left null, the default
   /// BinaryMessenger will be used which routes to the host platform.
   AndroidNotificationHostApi({BinaryMessenger? binaryMessenger, String messageChannelSuffix = ''})
-      : __pigeon_binaryMessenger = binaryMessenger,
-        __pigeon_messageChannelSuffix = messageChannelSuffix.isNotEmpty ? '.$messageChannelSuffix' : '';
-  final BinaryMessenger? __pigeon_binaryMessenger;
+      : pigeonVar_binaryMessenger = binaryMessenger,
+        pigeonVar_messageChannelSuffix = messageChannelSuffix.isNotEmpty ? '.$messageChannelSuffix' : '';
+  final BinaryMessenger? pigeonVar_binaryMessenger;
 
   static const MessageCodec<Object?> pigeonChannelCodec = _PigeonCodec();
 
-  final String __pigeon_messageChannelSuffix;
+  final String pigeonVar_messageChannelSuffix;
 
   /// Corresponds to `androidx.core.app.NotificationManagerCompat.createNotificationChannel`.
   ///
   /// See: https://developer.android.com/reference/androidx/core/app/NotificationManagerCompat#createNotificationChannel(androidx.core.app.NotificationChannelCompat)
   Future<void> createNotificationChannel(NotificationChannel channel) async {
-    final String __pigeon_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.createNotificationChannel$__pigeon_messageChannelSuffix';
-    final BasicMessageChannel<Object?> __pigeon_channel = BasicMessageChannel<Object?>(
-      __pigeon_channelName,
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.createNotificationChannel$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
       pigeonChannelCodec,
-      binaryMessenger: __pigeon_binaryMessenger,
+      binaryMessenger: pigeonVar_binaryMessenger,
     );
-    final List<Object?>? __pigeon_replyList =
-        await __pigeon_channel.send(<Object?>[channel]) as List<Object?>?;
-    if (__pigeon_replyList == null) {
-      throw _createConnectionError(__pigeon_channelName);
-    } else if (__pigeon_replyList.length > 1) {
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_channel.send(<Object?>[channel]) as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
       throw PlatformException(
-        code: __pigeon_replyList[0]! as String,
-        message: __pigeon_replyList[1] as String?,
-        details: __pigeon_replyList[2],
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
       );
     } else {
       return;
@@ -495,30 +498,30 @@ class AndroidNotificationHostApi {
   /// Corresponds to `androidx.core.app.NotificationManagerCompat.getNotificationChannelsCompat`.
   ///
   /// See: https://developer.android.com/reference/kotlin/androidx/core/app/NotificationManagerCompat#getNotificationChannelsCompat()
-  Future<List<NotificationChannel?>> getNotificationChannels() async {
-    final String __pigeon_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.getNotificationChannels$__pigeon_messageChannelSuffix';
-    final BasicMessageChannel<Object?> __pigeon_channel = BasicMessageChannel<Object?>(
-      __pigeon_channelName,
+  Future<List<NotificationChannel>> getNotificationChannels() async {
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.getNotificationChannels$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
       pigeonChannelCodec,
-      binaryMessenger: __pigeon_binaryMessenger,
+      binaryMessenger: pigeonVar_binaryMessenger,
     );
-    final List<Object?>? __pigeon_replyList =
-        await __pigeon_channel.send(null) as List<Object?>?;
-    if (__pigeon_replyList == null) {
-      throw _createConnectionError(__pigeon_channelName);
-    } else if (__pigeon_replyList.length > 1) {
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_channel.send(null) as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
       throw PlatformException(
-        code: __pigeon_replyList[0]! as String,
-        message: __pigeon_replyList[1] as String?,
-        details: __pigeon_replyList[2],
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
       );
-    } else if (__pigeon_replyList[0] == null) {
+    } else if (pigeonVar_replyList[0] == null) {
       throw PlatformException(
         code: 'null-error',
         message: 'Host platform returned null value for non-null return value.',
       );
     } else {
-      return (__pigeon_replyList[0] as List<Object?>?)!.cast<NotificationChannel?>();
+      return (pigeonVar_replyList[0] as List<Object?>?)!.cast<NotificationChannel>();
     }
   }
 
@@ -526,21 +529,21 @@ class AndroidNotificationHostApi {
   ///
   /// See: https://developer.android.com/reference/kotlin/androidx/core/app/NotificationManagerCompat#deleteNotificationChannel(java.lang.String)
   Future<void> deleteNotificationChannel(String channelId) async {
-    final String __pigeon_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.deleteNotificationChannel$__pigeon_messageChannelSuffix';
-    final BasicMessageChannel<Object?> __pigeon_channel = BasicMessageChannel<Object?>(
-      __pigeon_channelName,
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.deleteNotificationChannel$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
       pigeonChannelCodec,
-      binaryMessenger: __pigeon_binaryMessenger,
+      binaryMessenger: pigeonVar_binaryMessenger,
     );
-    final List<Object?>? __pigeon_replyList =
-        await __pigeon_channel.send(<Object?>[channelId]) as List<Object?>?;
-    if (__pigeon_replyList == null) {
-      throw _createConnectionError(__pigeon_channelName);
-    } else if (__pigeon_replyList.length > 1) {
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_channel.send(<Object?>[channelId]) as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
       throw PlatformException(
-        code: __pigeon_replyList[0]! as String,
-        message: __pigeon_replyList[1] as String?,
-        details: __pigeon_replyList[2],
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
       );
     } else {
       return;
@@ -557,30 +560,30 @@ class AndroidNotificationHostApi {
   /// Requires minimum of Android 10 (API 29) or higher.
   ///
   /// See: https://developer.android.com/reference/android/content/ContentResolver#query(android.net.Uri,%20java.lang.String[],%20java.lang.String,%20java.lang.String[],%20java.lang.String)
-  Future<List<StoredNotificationSound?>> listStoredSoundsInNotificationsDirectory() async {
-    final String __pigeon_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.listStoredSoundsInNotificationsDirectory$__pigeon_messageChannelSuffix';
-    final BasicMessageChannel<Object?> __pigeon_channel = BasicMessageChannel<Object?>(
-      __pigeon_channelName,
+  Future<List<StoredNotificationSound>> listStoredSoundsInNotificationsDirectory() async {
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.listStoredSoundsInNotificationsDirectory$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
       pigeonChannelCodec,
-      binaryMessenger: __pigeon_binaryMessenger,
+      binaryMessenger: pigeonVar_binaryMessenger,
     );
-    final List<Object?>? __pigeon_replyList =
-        await __pigeon_channel.send(null) as List<Object?>?;
-    if (__pigeon_replyList == null) {
-      throw _createConnectionError(__pigeon_channelName);
-    } else if (__pigeon_replyList.length > 1) {
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_channel.send(null) as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
       throw PlatformException(
-        code: __pigeon_replyList[0]! as String,
-        message: __pigeon_replyList[1] as String?,
-        details: __pigeon_replyList[2],
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
       );
-    } else if (__pigeon_replyList[0] == null) {
+    } else if (pigeonVar_replyList[0] == null) {
       throw PlatformException(
         code: 'null-error',
         message: 'Host platform returned null value for non-null return value.',
       );
     } else {
-      return (__pigeon_replyList[0] as List<Object?>?)!.cast<StoredNotificationSound?>();
+      return (pigeonVar_replyList[0] as List<Object?>?)!.cast<StoredNotificationSound>();
     }
   }
 
@@ -599,29 +602,29 @@ class AndroidNotificationHostApi {
   ///   https://developer.android.com/reference/android/content/ContentResolver#openOutputStream(android.net.Uri)
   ///   https://developer.android.com/reference/android/content/res/Resources#openRawResource(int)
   Future<String> copySoundResourceToMediaStore({required String targetFileDisplayName, required String sourceResourceName}) async {
-    final String __pigeon_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.copySoundResourceToMediaStore$__pigeon_messageChannelSuffix';
-    final BasicMessageChannel<Object?> __pigeon_channel = BasicMessageChannel<Object?>(
-      __pigeon_channelName,
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.copySoundResourceToMediaStore$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
       pigeonChannelCodec,
-      binaryMessenger: __pigeon_binaryMessenger,
+      binaryMessenger: pigeonVar_binaryMessenger,
     );
-    final List<Object?>? __pigeon_replyList =
-        await __pigeon_channel.send(<Object?>[targetFileDisplayName, sourceResourceName]) as List<Object?>?;
-    if (__pigeon_replyList == null) {
-      throw _createConnectionError(__pigeon_channelName);
-    } else if (__pigeon_replyList.length > 1) {
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_channel.send(<Object?>[targetFileDisplayName, sourceResourceName]) as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
       throw PlatformException(
-        code: __pigeon_replyList[0]! as String,
-        message: __pigeon_replyList[1] as String?,
-        details: __pigeon_replyList[2],
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
       );
-    } else if (__pigeon_replyList[0] == null) {
+    } else if (pigeonVar_replyList[0] == null) {
       throw PlatformException(
         code: 'null-error',
         message: 'Host platform returned null value for non-null return value.',
       );
     } else {
-      return (__pigeon_replyList[0] as String?)!;
+      return (pigeonVar_replyList[0] as String?)!;
     }
   }
 
@@ -642,22 +645,22 @@ class AndroidNotificationHostApi {
   /// See:
   ///   https://developer.android.com/reference/kotlin/android/app/NotificationManager.html#notify
   ///   https://developer.android.com/reference/androidx/core/app/NotificationCompat.Builder
-  Future<void> notify({String? tag, required int id, bool? autoCancel, required String channelId, int? color, PendingIntent? contentIntent, String? contentText, String? contentTitle, Map<String?, String?>? extras, String? groupKey, InboxStyle? inboxStyle, bool? isGroupSummary, MessagingStyle? messagingStyle, int? number, String? smallIconResourceName,}) async {
-    final String __pigeon_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.notify$__pigeon_messageChannelSuffix';
-    final BasicMessageChannel<Object?> __pigeon_channel = BasicMessageChannel<Object?>(
-      __pigeon_channelName,
+  Future<void> notify({String? tag, required int id, bool? autoCancel, required String channelId, int? color, PendingIntent? contentIntent, String? contentText, String? contentTitle, Map<String, String>? extras, String? groupKey, InboxStyle? inboxStyle, bool? isGroupSummary, MessagingStyle? messagingStyle, int? number, String? smallIconResourceName, }) async {
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.notify$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
       pigeonChannelCodec,
-      binaryMessenger: __pigeon_binaryMessenger,
+      binaryMessenger: pigeonVar_binaryMessenger,
     );
-    final List<Object?>? __pigeon_replyList =
-        await __pigeon_channel.send(<Object?>[tag, id, autoCancel, channelId, color, contentIntent, contentText, contentTitle, extras, groupKey, inboxStyle, isGroupSummary, messagingStyle, number, smallIconResourceName]) as List<Object?>?;
-    if (__pigeon_replyList == null) {
-      throw _createConnectionError(__pigeon_channelName);
-    } else if (__pigeon_replyList.length > 1) {
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_channel.send(<Object?>[tag, id, autoCancel, channelId, color, contentIntent, contentText, contentTitle, extras, groupKey, inboxStyle, isGroupSummary, messagingStyle, number, smallIconResourceName]) as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
       throw PlatformException(
-        code: __pigeon_replyList[0]! as String,
-        message: __pigeon_replyList[1] as String?,
-        details: __pigeon_replyList[2],
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
       );
     } else {
       return;
@@ -676,24 +679,24 @@ class AndroidNotificationHostApi {
   ///   https://developer.android.com/reference/kotlin/androidx/core/app/NotificationManagerCompat#getActiveNotifications()
   ///   https://developer.android.com/reference/kotlin/androidx/core/app/NotificationCompat.MessagingStyle#extractMessagingStyleFromNotification(android.app.Notification)
   Future<MessagingStyle?> getActiveNotificationMessagingStyleByTag(String tag) async {
-    final String __pigeon_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.getActiveNotificationMessagingStyleByTag$__pigeon_messageChannelSuffix';
-    final BasicMessageChannel<Object?> __pigeon_channel = BasicMessageChannel<Object?>(
-      __pigeon_channelName,
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.getActiveNotificationMessagingStyleByTag$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
       pigeonChannelCodec,
-      binaryMessenger: __pigeon_binaryMessenger,
+      binaryMessenger: pigeonVar_binaryMessenger,
     );
-    final List<Object?>? __pigeon_replyList =
-        await __pigeon_channel.send(<Object?>[tag]) as List<Object?>?;
-    if (__pigeon_replyList == null) {
-      throw _createConnectionError(__pigeon_channelName);
-    } else if (__pigeon_replyList.length > 1) {
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_channel.send(<Object?>[tag]) as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
       throw PlatformException(
-        code: __pigeon_replyList[0]! as String,
-        message: __pigeon_replyList[1] as String?,
-        details: __pigeon_replyList[2],
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
       );
     } else {
-      return (__pigeon_replyList[0] as MessagingStyle?);
+      return (pigeonVar_replyList[0] as MessagingStyle?);
     }
   }
 
@@ -705,30 +708,30 @@ class AndroidNotificationHostApi {
   /// is not of type string or is null, then that entry will be skipped.
   ///
   /// See: https://developer.android.com/reference/kotlin/androidx/core/app/NotificationManagerCompat?hl=en#getActiveNotifications()
-  Future<List<StatusBarNotification?>> getActiveNotifications({required List<String?> desiredExtras}) async {
-    final String __pigeon_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.getActiveNotifications$__pigeon_messageChannelSuffix';
-    final BasicMessageChannel<Object?> __pigeon_channel = BasicMessageChannel<Object?>(
-      __pigeon_channelName,
+  Future<List<StatusBarNotification>> getActiveNotifications({required List<String> desiredExtras}) async {
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.getActiveNotifications$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
       pigeonChannelCodec,
-      binaryMessenger: __pigeon_binaryMessenger,
+      binaryMessenger: pigeonVar_binaryMessenger,
     );
-    final List<Object?>? __pigeon_replyList =
-        await __pigeon_channel.send(<Object?>[desiredExtras]) as List<Object?>?;
-    if (__pigeon_replyList == null) {
-      throw _createConnectionError(__pigeon_channelName);
-    } else if (__pigeon_replyList.length > 1) {
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_channel.send(<Object?>[desiredExtras]) as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
       throw PlatformException(
-        code: __pigeon_replyList[0]! as String,
-        message: __pigeon_replyList[1] as String?,
-        details: __pigeon_replyList[2],
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
       );
-    } else if (__pigeon_replyList[0] == null) {
+    } else if (pigeonVar_replyList[0] == null) {
       throw PlatformException(
         code: 'null-error',
         message: 'Host platform returned null value for non-null return value.',
       );
     } else {
-      return (__pigeon_replyList[0] as List<Object?>?)!.cast<StatusBarNotification?>();
+      return (pigeonVar_replyList[0] as List<Object?>?)!.cast<StatusBarNotification>();
     }
   }
 
@@ -736,21 +739,21 @@ class AndroidNotificationHostApi {
   ///
   /// See: https://developer.android.com/reference/kotlin/androidx/core/app/NotificationManagerCompat?hl=en#cancel(java.lang.String,int)
   Future<void> cancel({String? tag, required int id}) async {
-    final String __pigeon_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.cancel$__pigeon_messageChannelSuffix';
-    final BasicMessageChannel<Object?> __pigeon_channel = BasicMessageChannel<Object?>(
-      __pigeon_channelName,
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.zulip.AndroidNotificationHostApi.cancel$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
       pigeonChannelCodec,
-      binaryMessenger: __pigeon_binaryMessenger,
+      binaryMessenger: pigeonVar_binaryMessenger,
     );
-    final List<Object?>? __pigeon_replyList =
-        await __pigeon_channel.send(<Object?>[tag, id]) as List<Object?>?;
-    if (__pigeon_replyList == null) {
-      throw _createConnectionError(__pigeon_channelName);
-    } else if (__pigeon_replyList.length > 1) {
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_channel.send(<Object?>[tag, id]) as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
       throw PlatformException(
-        code: __pigeon_replyList[0]! as String,
-        message: __pigeon_replyList[1] as String?,
-        details: __pigeon_replyList[2],
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
       );
     } else {
       return;
diff --git a/lib/licenses.dart b/lib/licenses.dart
index a52c3f3240..c23882bb83 100644
--- a/lib/licenses.dart
+++ b/lib/licenses.dart
@@ -23,6 +23,12 @@ Stream<LicenseEntry> additionalLicenses() async* {
         rootBundle.loadString('assets/Pygments/AUTHORS.txt'),
       ]);
 
+      // This does not need to be translated, as it is just a small fragment
+      // of text surrounded by a large quantity of English text that isn't
+      // translated anyway.
+      // (And it would be logistically tricky to translate, as this code is
+      // called from the `main` function before the [ZulipApp] widget is built,
+      // let alone has updated [GlobalLocalizations].)
       return '$licenseFileText\n\nAUTHORS file follows:\n\n$authorsFileText';
     }());
   yield LicenseEntryWithLineBreaks(
diff --git a/lib/model/autocomplete.dart b/lib/model/autocomplete.dart
index 5b66a6d52a..dffe44d6fe 100644
--- a/lib/model/autocomplete.dart
+++ b/lib/model/autocomplete.dart
@@ -6,7 +6,9 @@ import 'package:flutter/services.dart';
 import '../api/model/events.dart';
 import '../api/model/model.dart';
 import '../api/route/channels.dart';
+import '../generated/l10n/zulip_localizations.dart';
 import '../widgets/compose_box.dart';
+import 'compose.dart';
 import 'emoji.dart';
 import 'narrow.dart';
 import 'store.dart';
@@ -417,18 +419,21 @@ class MentionAutocompleteView extends AutocompleteView<MentionAutocompleteQuery,
   MentionAutocompleteView._({
     required super.store,
     required super.query,
+    required this.localizations,
     required this.narrow,
     required this.sortedUsers,
   });
 
   factory MentionAutocompleteView.init({
     required PerAccountStore store,
+    required ZulipLocalizations localizations,
     required Narrow narrow,
     required MentionAutocompleteQuery query,
   }) {
     final view = MentionAutocompleteView._(
       store: store,
       query: query,
+      localizations: localizations,
       narrow: narrow,
       sortedUsers: _usersByRelevance(store: store, narrow: narrow),
     );
@@ -438,23 +443,7 @@ class MentionAutocompleteView extends AutocompleteView<MentionAutocompleteQuery,
 
   final Narrow narrow;
   final List<User> sortedUsers;
-
-  @override
-  Future<List<MentionAutocompleteResult>?> computeResults() async {
-    final results = <MentionAutocompleteResult>[];
-    if (await filterCandidates(filter: _testUser,
-          candidates: sortedUsers, results: results)) {
-      return null;
-    }
-    return results;
-  }
-
-  MentionAutocompleteResult? _testUser(MentionAutocompleteQuery query, User user) {
-    if (query.testUser(user, store.autocompleteViewManager.autocompleteDataCache)) {
-      return UserMentionAutocompleteResult(userId: user.userId);
-    }
-    return null;
-  }
+  final ZulipLocalizations localizations;
 
   static List<User> _usersByRelevance({
     required PerAccountStore store,
@@ -485,7 +474,7 @@ class MentionAutocompleteView extends AutocompleteView<MentionAutocompleteQuery,
     required Narrow narrow,
   }) {
     int? streamId;
-    String? topic;
+    TopicName? topic;
     switch (narrow) {
       case ChannelNarrow():
         streamId = narrow.streamId;
@@ -506,11 +495,9 @@ class MentionAutocompleteView extends AutocompleteView<MentionAutocompleteQuery,
 
   static int _compareByRelevance(User userA, User userB, {
     required int? streamId,
-    required String? topic,
+    required TopicName? topic,
     required PerAccountStore store,
   }) {
-    // TODO(#234): give preference to "all", "everyone" or "stream"
-
     // TODO(#618): give preference to subscribed users first
 
     if (streamId != null) {
@@ -543,7 +530,7 @@ class MentionAutocompleteView extends AutocompleteView<MentionAutocompleteQuery,
   @visibleForTesting
   static int compareByRecency(User userA, User userB, {
     required int streamId,
-    required String? topic,
+    required TopicName? topic,
     required PerAccountStore store,
   }) {
     final recentSenders = store.recentSenders;
@@ -615,6 +602,59 @@ class MentionAutocompleteView extends AutocompleteView<MentionAutocompleteQuery,
     return userAName.compareTo(userBName); // TODO(i18n): add locale-aware sorting
   }
 
+  void computeWildcardMentionResults({
+    required List<MentionAutocompleteResult> results,
+    required bool isComposingChannelMessage,
+  }) {
+    if (query.silent) return;
+
+    bool tryOption(WildcardMentionOption option) {
+      if (query.testWildcardOption(option, localizations: localizations)) {
+        results.add(WildcardMentionAutocompleteResult(wildcardOption: option));
+        return true;
+      }
+      return false;
+    }
+
+    // Only one of the (all, everyone, channel, stream) channel wildcards are
+    // shown.
+    all: {
+      if (tryOption(WildcardMentionOption.all)) break all;
+      if (tryOption(WildcardMentionOption.everyone)) break all;
+      if (isComposingChannelMessage) {
+        final isChannelWildcardAvailable = store.account.zulipFeatureLevel >= 247; // TODO(server-9)
+        if (isChannelWildcardAvailable && tryOption(WildcardMentionOption.channel)) break all;
+        if (tryOption(WildcardMentionOption.stream)) break all;
+      }
+    }
+
+    final isTopicWildcardAvailable = store.account.zulipFeatureLevel >= 224; // TODO(server-8)
+    if (isComposingChannelMessage && isTopicWildcardAvailable) {
+      tryOption(WildcardMentionOption.topic);
+    }
+  }
+
+  @override
+  Future<List<MentionAutocompleteResult>?> computeResults() async {
+    final results = <MentionAutocompleteResult>[];
+    // Give priority to wildcard mentions.
+    computeWildcardMentionResults(results: results,
+      isComposingChannelMessage: narrow is ChannelNarrow || narrow is TopicNarrow);
+
+    if (await filterCandidates(filter: _testUser,
+        candidates: sortedUsers, results: results)) {
+      return null;
+    }
+    return results;
+  }
+
+  MentionAutocompleteResult? _testUser(MentionAutocompleteQuery query, User user) {
+    if (query.testUser(user, store.autocompleteViewManager.autocompleteDataCache)) {
+      return UserMentionAutocompleteResult(userId: user.userId);
+    }
+    return null;
+  }
+
   @override
   void dispose() {
     store.autocompleteViewManager.unregisterMentionAutocomplete(this);
@@ -642,13 +682,17 @@ class MentionAutocompleteView extends AutocompleteView<MentionAutocompleteQuery,
 /// to prepare for whatever particular form of searching will be done
 /// for the given type of autocomplete interaction.
 abstract class AutocompleteQuery {
-  AutocompleteQuery(this.raw)
-    : _lowercaseWords = raw.toLowerCase().split(' ');
+  AutocompleteQuery(this.raw) {
+    _lowercase = raw.toLowerCase();
+    _lowercaseWords = _lowercase.split(' ');
+  }
 
   /// The actual string the user entered.
   final String raw;
 
-  final List<String> _lowercaseWords;
+  late final String _lowercase;
+
+  late final List<String> _lowercaseWords;
 
   /// Whether all of this query's words have matches in [words] that appear in order.
   ///
@@ -679,7 +723,11 @@ abstract class ComposeAutocompleteQuery extends AutocompleteQuery {
 
   /// Construct an [AutocompleteView] initialized with this query
   /// and ready to handle queries of the same type.
-  ComposeAutocompleteView initViewModel(PerAccountStore store, Narrow narrow);
+  ComposeAutocompleteView initViewModel({
+    required PerAccountStore store,
+    required ZulipLocalizations localizations,
+    required Narrow narrow,
+  });
 }
 
 /// A @-mention autocomplete query, used by [MentionAutocompleteView].
@@ -690,13 +738,24 @@ class MentionAutocompleteQuery extends ComposeAutocompleteQuery {
   final bool silent;
 
   @override
-  MentionAutocompleteView initViewModel(PerAccountStore store, Narrow narrow) {
-    return MentionAutocompleteView.init(store: store, narrow: narrow, query: this);
+  MentionAutocompleteView initViewModel({
+    required PerAccountStore store,
+    required ZulipLocalizations localizations,
+    required Narrow narrow,
+  }) {
+    return MentionAutocompleteView.init(
+      store: store, localizations: localizations, narrow: narrow, query: this);
+  }
+
+  bool testWildcardOption(WildcardMentionOption wildcardOption, {
+      required ZulipLocalizations localizations}) {
+    // TODO(#237): match insensitively to diacritics
+    return wildcardOption.canonicalString.contains(_lowercase)
+      || wildcardOption.localizedCanonicalString(localizations).contains(_lowercase);
   }
 
   bool testUser(User user, AutocompleteDataCache cache) {
     // TODO(#236) test email too, not just name
-
     if (!user.isActive) return false;
 
     return _testName(user, cache);
@@ -720,6 +779,19 @@ class MentionAutocompleteQuery extends ComposeAutocompleteQuery {
   int get hashCode => Object.hash('MentionAutocompleteQuery', raw, silent);
 }
 
+extension WildcardMentionOptionExtension on WildcardMentionOption {
+  /// A translation of [canonicalString], from [localizations].
+  String localizedCanonicalString(ZulipLocalizations localizations) {
+    return switch (this) {
+      WildcardMentionOption.all      => localizations.wildcardMentionAll,
+      WildcardMentionOption.everyone => localizations.wildcardMentionEveryone,
+      WildcardMentionOption.channel  => localizations.wildcardMentionChannel,
+      WildcardMentionOption.stream   => localizations.wildcardMentionStream,
+      WildcardMentionOption.topic    => localizations.wildcardMentionTopic,
+    };
+  }
+}
+
 /// Cached data that is used for autocomplete
 /// but kept around in between autocomplete interactions.
 ///
@@ -788,9 +860,14 @@ class UserMentionAutocompleteResult extends MentionAutocompleteResult {
   final int userId;
 }
 
-// TODO(#233): // class UserGroupMentionAutocompleteResult extends MentionAutocompleteResult {
+/// An autocomplete result for an @-mention of all the users in a conversation.
+class WildcardMentionAutocompleteResult extends MentionAutocompleteResult {
+  WildcardMentionAutocompleteResult({required this.wildcardOption});
+
+  final WildcardMentionOption wildcardOption;
+}
 
-// TODO(#234): // class WildcardMentionAutocompleteResult extends MentionAutocompleteResult {
+// TODO(#233): // class UserGroupMentionAutocompleteResult extends MentionAutocompleteResult {
 
 /// An autocomplete interaction for choosing a topic for a message.
 class TopicAutocompleteView extends AutocompleteView<TopicAutocompleteQuery, TopicAutocompleteResult> {
@@ -815,7 +892,7 @@ class TopicAutocompleteView extends AutocompleteView<TopicAutocompleteQuery, Top
   /// The channel/stream the eventual message will be sent to.
   final int streamId;
 
-  Iterable<String> _topics = [];
+  Iterable<TopicName> _topics = [];
   bool _isFetching = false;
 
   /// Fetches topics of the current stream narrow, expected to fetch
@@ -843,7 +920,7 @@ class TopicAutocompleteView extends AutocompleteView<TopicAutocompleteQuery, Top
     return results;
   }
 
-  TopicAutocompleteResult? _testTopic(TopicAutocompleteQuery query, String topic) {
+  TopicAutocompleteResult? _testTopic(TopicAutocompleteQuery query, TopicName topic) {
     if (query.testTopic(topic)) {
       return TopicAutocompleteResult(topic: topic);
     }
@@ -862,9 +939,10 @@ class TopicAutocompleteView extends AutocompleteView<TopicAutocompleteQuery, Top
 class TopicAutocompleteQuery extends AutocompleteQuery {
   TopicAutocompleteQuery(super.raw);
 
-  bool testTopic(String topic) {
+  bool testTopic(TopicName topic) {
     // TODO(#881): Sort by match relevance, like web does.
-    return topic != raw && topic.toLowerCase().contains(raw.toLowerCase());
+    return topic.displayName != raw
+      && topic.displayName.toLowerCase().contains(raw.toLowerCase());
   }
 
   @override
@@ -883,7 +961,7 @@ class TopicAutocompleteQuery extends AutocompleteQuery {
 
 /// A topic chosen in an autocomplete interaction, via a [TopicAutocompleteView].
 class TopicAutocompleteResult extends AutocompleteResult {
-  final String topic;
+  final TopicName topic;
 
   TopicAutocompleteResult({required this.topic});
 }
diff --git a/lib/model/channel.dart b/lib/model/channel.dart
index 3ea29d7538..3f5fbe33af 100644
--- a/lib/model/channel.dart
+++ b/lib/model/channel.dart
@@ -41,7 +41,7 @@ mixin ChannelStore {
   ///
   /// For policies directly applicable in the UI, see
   /// [isTopicVisibleInStream] and [isTopicVisible].
-  UserTopicVisibilityPolicy topicVisibilityPolicy(int streamId, String topic);
+  UserTopicVisibilityPolicy topicVisibilityPolicy(int streamId, TopicName topic);
 
   /// The raw data structure underlying [topicVisibilityPolicy].
   ///
@@ -51,7 +51,7 @@ mixin ChannelStore {
   /// and on the other hand being a concrete, finite data structure that
   /// can be compared using `deepEquals`.
   @visibleForTesting
-  Map<int, Map<String, UserTopicVisibilityPolicy>> get debugTopicVisibility;
+  Map<int, Map<TopicName, UserTopicVisibilityPolicy>> get debugTopicVisibility;
 
   /// Whether this topic should appear when already focusing on its stream.
   ///
@@ -63,7 +63,7 @@ mixin ChannelStore {
   ///
   /// For UI contexts that are not specific to a particular stream, see
   /// [isTopicVisible].
-  bool isTopicVisibleInStream(int streamId, String topic) {
+  bool isTopicVisibleInStream(int streamId, TopicName topic) {
     return _isTopicVisibleInStream(topicVisibilityPolicy(streamId, topic));
   }
 
@@ -100,7 +100,7 @@ mixin ChannelStore {
   ///
   /// For UI contexts that are specific to a particular stream, see
   /// [isTopicVisibleInStream].
-  bool isTopicVisible(int streamId, String topic) {
+  bool isTopicVisible(int streamId, TopicName topic) {
     return _isTopicVisible(streamId, topicVisibilityPolicy(streamId, topic));
   }
 
@@ -171,7 +171,7 @@ class ChannelStoreImpl with ChannelStore {
       streams.putIfAbsent(stream.streamId, () => stream);
     }
 
-    final topicVisibility = <int, Map<String, UserTopicVisibilityPolicy>>{};
+    final topicVisibility = <int, Map<TopicName, UserTopicVisibilityPolicy>>{};
     for (final item in initialSnapshot.userTopics ?? const <UserTopicItem>[]) {
       if (_warnInvalidVisibilityPolicy(item.visibilityPolicy)) {
         // Not a value we expect. Keep it out of our data structures. // TODO(log)
@@ -204,12 +204,12 @@ class ChannelStoreImpl with ChannelStore {
   final Map<int, Subscription> subscriptions;
 
   @override
-  Map<int, Map<String, UserTopicVisibilityPolicy>> get debugTopicVisibility => topicVisibility;
+  Map<int, Map<TopicName, UserTopicVisibilityPolicy>> get debugTopicVisibility => topicVisibility;
 
-  final Map<int, Map<String, UserTopicVisibilityPolicy>> topicVisibility;
+  final Map<int, Map<TopicName, UserTopicVisibilityPolicy>> topicVisibility;
 
   @override
-  UserTopicVisibilityPolicy topicVisibilityPolicy(int streamId, String topic) {
+  UserTopicVisibilityPolicy topicVisibilityPolicy(int streamId, TopicName topic) {
     return topicVisibility[streamId]?[topic] ?? UserTopicVisibilityPolicy.none;
   }
 
diff --git a/lib/model/compose.dart b/lib/model/compose.dart
index b59a3efcc7..54c7f6ce00 100644
--- a/lib/model/compose.dart
+++ b/lib/model/compose.dart
@@ -1,10 +1,33 @@
 import 'dart:math';
 
 import '../api/model/model.dart';
+import '../generated/l10n/zulip_localizations.dart';
 import 'internal_link.dart';
 import 'narrow.dart';
 import 'store.dart';
 
+/// The available user wildcard mention options,
+/// known to the server as [canonicalString].
+///
+/// See API docs:
+///   https://zulip.com/api/message-formatting#mentions-and-silent-mentions
+enum WildcardMentionOption {
+  all(canonicalString: 'all'),
+  everyone(canonicalString: 'everyone'),
+  channel(canonicalString: 'channel'),
+  // TODO(server-9): Deprecated in FL 247. Empirically, current servers (FL 339)
+  // still parse "@**stream**" in messages though.
+  stream(canonicalString: 'stream'),
+  topic(canonicalString: 'topic'); // TODO(server-8): New in FL 224.
+
+  const WildcardMentionOption({required this.canonicalString});
+
+  /// The string identifying this option (e.g. "all" as in "@**all**").
+  final String canonicalString;
+
+  String get name => throw UnsupportedError('Use [canonicalString] instead.');
+}
+
 //
 // Put functions for nontrivial message-content generation in this file.
 //
@@ -101,18 +124,42 @@ String wrapWithBacktickFence({required String content, String? infoString}) {
   return resultBuffer.toString();
 }
 
-/// An @-mention, like @**Chris Bobbe|13313**.
+/// An @-mention of an individual user, like @**Chris Bobbe|13313**.
 ///
 /// To omit the user ID part ("|13313") whenever the name part is unambiguous,
 /// pass a Map of all users we know about. This means accepting a linear scan
 /// through all users; avoid it in performance-sensitive codepaths.
-String mention(User user, {bool silent = false, Map<int, User>? users}) {
+String userMention(User user, {bool silent = false, Map<int, User>? users}) {
   bool includeUserId = users == null
     || users.values.where((u) => u.fullName == user.fullName).take(2).length == 2;
 
   return '@${silent ? '_' : ''}**${user.fullName}${includeUserId ? '|${user.userId}' : ''}**';
 }
 
+/// An @-mention of all the users in a conversation, like @**channel**.
+String wildcardMention(WildcardMentionOption wildcardOption, {
+  required PerAccountStore store,
+}) {
+  final isChannelWildcardAvailable = store.account.zulipFeatureLevel >= 247; // TODO(server-9)
+  final isTopicWildcardAvailable = store.account.zulipFeatureLevel >= 224; // TODO(server-8)
+
+  String name = wildcardOption.canonicalString;
+  switch (wildcardOption) {
+    case WildcardMentionOption.all:
+    case WildcardMentionOption.everyone:
+      break;
+    case WildcardMentionOption.channel:
+      assert(isChannelWildcardAvailable);
+    case WildcardMentionOption.stream:
+      if (isChannelWildcardAvailable) {
+        name = WildcardMentionOption.channel.canonicalString;
+      }
+    case WildcardMentionOption.topic:
+      assert(isTopicWildcardAvailable);
+  }
+  return '@**$name**';
+}
+
 /// https://spec.commonmark.org/0.30/#inline-link
 ///
 /// The "link text" is made by enclosing [visibleText] in square brackets.
@@ -136,7 +183,9 @@ String inlineLink(String visibleText, Uri? destination) {
 }
 
 /// What we show while fetching the target message's raw Markdown.
-String quoteAndReplyPlaceholder(PerAccountStore store, {
+String quoteAndReplyPlaceholder(
+  ZulipLocalizations zulipLocalizations,
+  PerAccountStore store, {
   required Message message,
 }) {
   final sender = store.users[message.senderId];
@@ -145,8 +194,8 @@ String quoteAndReplyPlaceholder(PerAccountStore store, {
     SendableNarrow.ofMessage(message, selfUserId: store.selfUserId),
     nearMessageId: message.id);
   // See note in [quoteAndReply] about asking `mention` to omit the |<id> part.
-  return '${mention(sender!, silent: true)} ${inlineLink('said', url)}: ' // TODO(i18n) ?
-    '*(loading message ${message.id})*\n'; // TODO(i18n) ?
+  return '${userMention(sender!, silent: true)} ${inlineLink('said', url)}: ' // TODO(#1285)
+    '*${zulipLocalizations.composeBoxLoadingMessage(message.id)}*\n';
 }
 
 /// Quote-and-reply syntax.
@@ -169,6 +218,6 @@ String quoteAndReply(PerAccountStore store, {
     // Could ask `mention` to omit the |<id> part unless the mention is ambiguous…
     // but that would mean a linear scan through all users, and the extra noise
     // won't much matter with the already probably-long message link in there too.
-    return '${mention(sender!, silent: true)} ${inlineLink('said', url)}:\n' // TODO(i18n) ?
+    return '${userMention(sender!, silent: true)} ${inlineLink('said', url)}:\n' // TODO(#1285)
       '${wrapWithBacktickFence(content: rawContent, infoString: 'quote')}';
 }
diff --git a/lib/model/content.dart b/lib/model/content.dart
index c98a5ceaaf..e228163a2e 100644
--- a/lib/model/content.dart
+++ b/lib/model/content.dart
@@ -786,7 +786,7 @@ class MathInlineNode extends InlineContentNode {
 class GlobalTimeNode extends InlineContentNode {
   const GlobalTimeNode({super.debugHtmlNode, required this.datetime});
 
-  /// Always in UTC, enforced in [_ZulipContentParser.parseInlineContent].
+  /// Always in UTC, enforced in [_ZulipInlineContentParser.parseInlineContent].
   final DateTime datetime;
 
   @override
@@ -806,72 +806,68 @@ class GlobalTimeNode extends InlineContentNode {
 
 ////////////////////////////////////////////////////////////////
 
-/// What sort of nodes a [_ZulipContentParser] is currently expecting to find.
-enum _ParserContext {
-  /// The parser is currently looking for block nodes.
-  block,
+String? _parseMath(dom.Element element, {required bool block}) {
+  final dom.Element katexElement;
+  if (!block) {
+    assert(element.localName == 'span' && element.className == 'katex');
 
-  /// The parser is currently looking for inline nodes.
-  inline,
-}
-
-class _ZulipContentParser {
-  /// The current state of what sort of nodes the parser is looking for.
-  ///
-  /// This exists for the sake of debug-mode checks,
-  /// and should be read or updated only inside an assertion.
-  _ParserContext _debugParserContext = _ParserContext.block;
-
-  String? parseMath(dom.Element element, {required bool block}) {
-    assert(block == (_debugParserContext == _ParserContext.block));
-
-    final dom.Element katexElement;
-    if (!block) {
-      assert(element.localName == 'span' && element.className == 'katex');
+    katexElement = element;
+  } else {
+    assert(element.localName == 'span' && element.className == 'katex-display');
 
-      katexElement = element;
-    } else {
-      assert(element.localName == 'span' && element.className == 'katex-display');
-
-      if (element.nodes.length != 1) return null;
-      final child = element.nodes.single;
-      if (child is! dom.Element) return null;
-      if (child.localName != 'span') return null;
-      if (child.className != 'katex') return null;
-      katexElement = child;
-    }
-
-    // Expect two children span.katex-mathml, span.katex-html .
-    // For now we only care about the .katex-mathml .
-    if (katexElement.nodes.isEmpty) return null;
-    final child = katexElement.nodes.first;
+    if (element.nodes.length != 1) return null;
+    final child = element.nodes.single;
     if (child is! dom.Element) return null;
     if (child.localName != 'span') return null;
-    if (child.className != 'katex-mathml') return null;
-
-    if (child.nodes.length != 1) return null;
-    final grandchild = child.nodes.single;
-    if (grandchild is! dom.Element) return null;
-    if (grandchild.localName != 'math') return null;
-    if (grandchild.attributes['display'] != (block ? 'block' : null)) return null;
-    if (grandchild.namespaceUri != 'http://www.w3.org/1998/Math/MathML') return null;
-
-    if (grandchild.nodes.length != 1) return null;
-    final greatgrand = grandchild.nodes.single;
-    if (greatgrand is! dom.Element) return null;
-    if (greatgrand.localName != 'semantics') return null;
-
-    if (greatgrand.nodes.isEmpty) return null;
-    final descendant4 = greatgrand.nodes.last;
-    if (descendant4 is! dom.Element) return null;
-    if (descendant4.localName != 'annotation') return null;
-    if (descendant4.attributes['encoding'] != 'application/x-tex') return null;
-
-    return descendant4.text.trim();
+    if (child.className != 'katex') return null;
+    katexElement = child;
+  }
+
+  // Expect two children span.katex-mathml, span.katex-html .
+  // For now we only care about the .katex-mathml .
+  if (katexElement.nodes.isEmpty) return null;
+  final child = katexElement.nodes.first;
+  if (child is! dom.Element) return null;
+  if (child.localName != 'span') return null;
+  if (child.className != 'katex-mathml') return null;
+
+  if (child.nodes.length != 1) return null;
+  final grandchild = child.nodes.single;
+  if (grandchild is! dom.Element) return null;
+  if (grandchild.localName != 'math') return null;
+  if (grandchild.attributes['display'] != (block ? 'block' : null)) return null;
+  if (grandchild.namespaceUri != 'http://www.w3.org/1998/Math/MathML') return null;
+
+  if (grandchild.nodes.length != 1) return null;
+  final greatgrand = grandchild.nodes.single;
+  if (greatgrand is! dom.Element) return null;
+  if (greatgrand.localName != 'semantics') return null;
+
+  if (greatgrand.nodes.isEmpty) return null;
+  final descendant4 = greatgrand.nodes.last;
+  if (descendant4 is! dom.Element) return null;
+  if (descendant4.localName != 'annotation') return null;
+  if (descendant4.attributes['encoding'] != 'application/x-tex') return null;
+
+  return descendant4.text.trim();
+}
+
+/// Parser for the inline-content subtrees within Zulip content HTML.
+///
+/// The only entry point to this class is [parseBlockInline].
+///
+/// After a call to [parseBlockInline] returns, the [_ZulipInlineContentParser]
+/// instance has been reset to its starting state, and can be re-used for
+/// parsing other subtrees.
+class _ZulipInlineContentParser {
+  InlineContentNode? parseInlineMath(dom.Element element) {
+    final debugHtmlNode = kDebugMode ? element : null;
+    final texSource = _parseMath(element, block: false);
+    if (texSource == null) return null;
+    return MathInlineNode(texSource: texSource, debugHtmlNode: debugHtmlNode);
   }
 
   UserMentionNode? parseUserMention(dom.Element element) {
-    assert(_debugParserContext == _ParserContext.inline);
     assert(element.localName == 'span');
     final debugHtmlNode = kDebugMode ? element : null;
 
@@ -945,7 +941,6 @@ class _ZulipContentParser {
   static final _emojiCodeFromClassNameRegexp = RegExp(r"emoji-([^ ]+)");
 
   InlineContentNode parseInlineContent(dom.Node node) {
-    assert(_debugParserContext == _ParserContext.inline);
     final debugHtmlNode = kDebugMode ? node : null;
     InlineContentNode unimplemented() => UnimplementedInlineContentNode(htmlNode: node);
 
@@ -1025,9 +1020,7 @@ class _ZulipContentParser {
     }
 
     if (localName == 'span' && className == 'katex') {
-      final texSource = parseMath(element, block: false);
-      if (texSource == null) return unimplemented();
-      return MathInlineNode(texSource: texSource, debugHtmlNode: debugHtmlNode);
+      return parseInlineMath(element) ?? unimplemented();
     }
 
     // TODO more types of node
@@ -1035,26 +1028,41 @@ class _ZulipContentParser {
   }
 
   List<InlineContentNode> parseInlineContentList(List<dom.Node> nodes) {
-    assert(_debugParserContext == _ParserContext.inline);
     return nodes.map(parseInlineContent).toList(growable: false);
   }
 
+  /// Parse the children of a [BlockInlineContainerNode], making up a
+  /// complete subtree of inline content with no further inline ancestors.
   ({List<InlineContentNode> nodes, List<LinkNode>? links}) parseBlockInline(List<dom.Node> nodes) {
-    assert(_debugParserContext == _ParserContext.block);
-    assert(() {
-      _debugParserContext = _ParserContext.inline;
-      return true;
-    }());
     final resultNodes = parseInlineContentList(nodes);
-    assert(() {
-      _debugParserContext = _ParserContext.block;
-      return true;
-    }());
     return (nodes: resultNodes, links: _takeLinkNodes());
   }
+}
+
+/// Parser for a complete piece of Zulip HTML content, a [ZulipContent].
+///
+/// The only entry point to this class is [parse].
+class _ZulipContentParser {
+  /// The single inline-content parser used and re-used throughout parsing of
+  /// a complete piece of Zulip HTML content.
+  ///
+  /// Because block content can never appear nested inside inline content,
+  /// there's never a need for more than one of these at a time,
+  /// so we can allocate just one up front.
+  final inlineParser = _ZulipInlineContentParser();
+
+  ({List<InlineContentNode> nodes, List<LinkNode>? links}) parseBlockInline(List<dom.Node> nodes) {
+    return inlineParser.parseBlockInline(nodes);
+  }
+
+  BlockContentNode parseMathBlock(dom.Element element) {
+    final debugHtmlNode = kDebugMode ? element : null;
+    final texSource = _parseMath(element, block: true);
+    if (texSource == null) return UnimplementedBlockContentNode(htmlNode: element);
+    return MathBlockNode(texSource: texSource, debugHtmlNode: debugHtmlNode);
+  }
 
   BlockContentNode parseListNode(dom.Element element) {
-    assert(_debugParserContext == _ParserContext.block);
     ListStyle? listStyle;
     switch (element.localName) {
       case 'ol': listStyle = ListStyle.ordered; break;
@@ -1077,7 +1085,6 @@ class _ZulipContentParser {
   }
 
   BlockContentNode parseSpoilerNode(dom.Element divElement) {
-    assert(_debugParserContext == _ParserContext.block);
     assert(divElement.localName == 'div'
         && divElement.className == 'spoiler-block');
 
@@ -1097,7 +1104,6 @@ class _ZulipContentParser {
   }
 
   BlockContentNode parseCodeBlock(dom.Element divElement) {
-    assert(_debugParserContext == _ParserContext.block);
     final mainElement = () {
       assert(divElement.localName == 'div'
           && divElement.className == "codehilite");
@@ -1180,7 +1186,6 @@ class _ZulipContentParser {
   static final _imageDimensionsRegExp = RegExp(r'^(\d+)x(\d+)$');
 
   BlockContentNode parseImageNode(dom.Element divElement) {
-    assert(_debugParserContext == _ParserContext.block);
     final elements = () {
       assert(divElement.localName == 'div'
           && divElement.className == 'message_inline_image');
@@ -1272,7 +1277,6 @@ class _ZulipContentParser {
   }();
 
   BlockContentNode parseInlineVideoNode(dom.Element divElement) {
-    assert(_debugParserContext == _ParserContext.block);
     assert(divElement.localName == 'div'
       && _videoClassNameRegexp.hasMatch(divElement.className));
 
@@ -1305,7 +1309,6 @@ class _ZulipContentParser {
   }
 
   BlockContentNode parseEmbedVideoNode(dom.Element divElement) {
-    assert(_debugParserContext == _ParserContext.block);
     assert(divElement.localName == 'div'
       && _videoClassNameRegexp.hasMatch(divElement.className));
 
@@ -1344,7 +1347,6 @@ class _ZulipContentParser {
   }
 
   BlockContentNode parseTableContent(dom.Element tableElement) {
-    assert(_debugParserContext == _ParserContext.block);
     assert(tableElement.localName == 'table'
         && tableElement.className.isEmpty);
 
@@ -1452,7 +1454,6 @@ class _ZulipContentParser {
   }
 
   BlockContentNode parseBlockContent(dom.Node node) {
-    assert(_debugParserContext == _ParserContext.block);
     final debugHtmlNode = kDebugMode ? node : null;
     if (node is! dom.Element) {
       return UnimplementedBlockContentNode(htmlNode: node);
@@ -1480,9 +1481,7 @@ class _ZulipContentParser {
             // The case with the `<br>\n` can happen when at the end of a quote;
             // it seems like a glitch in the server's Markdown processing,
             // so hopefully there just aren't any further such glitches.
-            final texSource = parseMath(child, block: true);
-            if (texSource == null) return UnimplementedBlockContentNode(htmlNode: node);
-            return MathBlockNode(texSource: texSource, debugHtmlNode: debugHtmlNode);
+            return parseMathBlock(child);
           }
         }
       }
@@ -1579,10 +1578,15 @@ class _ZulipContentParser {
   ///
   /// See [ParagraphNode].
   List<BlockContentNode> parseImplicitParagraphBlockContentList(dom.NodeList nodes) {
-    assert(_debugParserContext == _ParserContext.block);
     final List<BlockContentNode> result = [];
-    final List<dom.Node> currentParagraph = [];
+
     List<ImageNode> imageNodes = [];
+    void consumeImageNodes() {
+      result.add(ImageNodeList(imageNodes));
+      imageNodes = [];
+    }
+
+    final List<dom.Node> currentParagraph = [];
     void consumeParagraph() {
       final parsed = parseBlockInline(currentParagraph);
       result.add(ParagraphNode(
@@ -1597,8 +1601,7 @@ class _ZulipContentParser {
 
       if (_isPossibleInlineNode(node)) {
         if (imageNodes.isNotEmpty) {
-          result.add(ImageNodeList(imageNodes));
-          imageNodes = [];
+          consumeImageNodes();
           // In a context where paragraphs are implicit it should be impossible
           // to have more paragraph content after image previews.
           result.add(UnimplementedBlockContentNode(htmlNode: node));
@@ -1613,24 +1616,25 @@ class _ZulipContentParser {
         imageNodes.add(block);
         continue;
       }
-      if (imageNodes.isNotEmpty) {
-        result.add(ImageNodeList(imageNodes));
-        imageNodes = [];
-      }
+      if (imageNodes.isNotEmpty) consumeImageNodes();
       result.add(block);
     }
     if (currentParagraph.isNotEmpty) consumeParagraph();
-    if (imageNodes.isNotEmpty) result.add(ImageNodeList(imageNodes));
-
+    if (imageNodes.isNotEmpty) consumeImageNodes();
     return result;
   }
 
   static final _redundantLineBreaksRegexp = RegExp(r'^\n+$');
 
   List<BlockContentNode> parseBlockContentList(dom.NodeList nodes) {
-    assert(_debugParserContext == _ParserContext.block);
     final List<BlockContentNode> result = [];
+
     List<ImageNode> imageNodes = [];
+    void consumeImageNodes() {
+      result.add(ImageNodeList(imageNodes));
+      imageNodes = [];
+    }
+
     for (final node in nodes) {
       // We get a bunch of newline Text nodes between paragraphs.
       // A browser seems to ignore these; let's do the same.
@@ -1643,13 +1647,10 @@ class _ZulipContentParser {
         imageNodes.add(block);
         continue;
       }
-      if (imageNodes.isNotEmpty) {
-        result.add(ImageNodeList(imageNodes));
-        imageNodes = [];
-      }
+      if (imageNodes.isNotEmpty) consumeImageNodes();
       result.add(block);
     }
-    if (imageNodes.isNotEmpty) result.add(ImageNodeList(imageNodes));
+    if (imageNodes.isNotEmpty) consumeImageNodes();
     return result;
   }
 
@@ -1660,6 +1661,8 @@ class _ZulipContentParser {
   }
 }
 
+/// Parse a complete piece of Zulip HTML content,
+/// such as an entire value of [Message.content].
 ZulipContent parseContent(String html) {
   return _ZulipContentParser().parse(html);
 }
diff --git a/lib/model/emoji.dart b/lib/model/emoji.dart
index 2728600e44..b0ec5f7324 100644
--- a/lib/model/emoji.dart
+++ b/lib/model/emoji.dart
@@ -5,6 +5,7 @@ import '../api/model/events.dart';
 import '../api/model/initial_snapshot.dart';
 import '../api/model/model.dart';
 import '../api/route/realm.dart';
+import '../generated/l10n/zulip_localizations.dart';
 import 'algorithms.dart';
 import 'autocomplete.dart';
 import 'narrow.dart';
@@ -465,7 +466,11 @@ class EmojiAutocompleteQuery extends ComposeAutocompleteQuery {
   }
 
   @override
-  EmojiAutocompleteView initViewModel(PerAccountStore store, Narrow narrow) {
+  EmojiAutocompleteView initViewModel({
+    required PerAccountStore store,
+    required ZulipLocalizations localizations,
+    required Narrow narrow,
+  }) {
     return EmojiAutocompleteView.init(store: store, query: this);
   }
 
diff --git a/lib/model/internal_link.dart b/lib/model/internal_link.dart
index a5dd23c2a2..db11115cf3 100644
--- a/lib/model/internal_link.dart
+++ b/lib/model/internal_link.dart
@@ -1,6 +1,7 @@
 import 'package:flutter/foundation.dart';
 import 'package:json_annotation/json_annotation.dart';
 
+import '../api/model/model.dart';
 import '../api/model/narrow.dart';
 import 'narrow.dart';
 import 'store.dart';
@@ -76,7 +77,7 @@ Uri narrowLink(PerAccountStore store, Narrow narrow, {int? nearMessageId}) {
         final slugifiedName = _encodeHashComponent(name.replaceAll(' ', '-'));
         fragment.write('$streamId-$slugifiedName');
       case ApiNarrowTopic():
-        fragment.write(_encodeHashComponent(element.operand));
+        fragment.write(_encodeHashComponent(element.operand.apiName));
       case ApiNarrowDmModern():
         final suffix = element.operand.length >= 3 ? 'group' : 'dm';
         fragment.write('${element.operand.join(',')}-$suffix');
@@ -178,7 +179,7 @@ Narrow? _interpretNarrowSegments(List<String> segments, PerAccountStore store) {
         if (topicElement != null) return null;
         final String? topic = decodeHashComponent(operand);
         if (topic == null) return null;
-        topicElement = ApiNarrowTopic(topic, negated: negated);
+        topicElement = ApiNarrowTopic(TopicName(topic), negated: negated);
 
       case _NarrowOperator.dm:
       case _NarrowOperator.pmWith:
diff --git a/lib/model/localizations.dart b/lib/model/localizations.dart
index 0f719fed06..07598cd8fe 100644
--- a/lib/model/localizations.dart
+++ b/lib/model/localizations.dart
@@ -1,6 +1,17 @@
 import '../generated/l10n/zulip_localizations.dart';
 
 abstract final class GlobalLocalizations {
+  /// The [ZulipLocalizations] for the user's chosen language and locale.
+  ///
+  /// Where possible, the [ZulipLocalizations] should be acquired
+  /// through [ZulipLocalizations.of] instead, using a [BuildContext].
+  /// This static field is to be used where access to a [BuildContext]
+  /// is impractical, such as in the API bindings
+  /// (which use localizations when throwing exceptions).
+  ///
+  /// This gets set during app startup once we have the user's choice of locale.
+  /// If accessed before that point, it uses the app's first supported locale,
+  /// namely 'en'.
   static ZulipLocalizations zulipLocalizations =
     lookupZulipLocalizations(ZulipLocalizations.supportedLocales.first);
 }
diff --git a/lib/model/message_list.dart b/lib/model/message_list.dart
index ecfb16c2b9..670785ac4e 100644
--- a/lib/model/message_list.dart
+++ b/lib/model/message_list.dart
@@ -352,7 +352,7 @@ mixin _MessageSequence {
 bool haveSameRecipient(Message prevMessage, Message message) {
   if (prevMessage is StreamMessage && message is StreamMessage) {
     if (prevMessage.streamId != message.streamId) return false;
-    if (prevMessage.topic.toLowerCase() != message.topic.toLowerCase()) return false;
+    if (prevMessage.topic.canonicalize() != message.topic.canonicalize()) return false;
   } else if (prevMessage is DmMessage && message is DmMessage) {
     if (!_equalIdSequences(prevMessage.allRecipientIds, message.allRecipientIds)) {
       return false;
@@ -686,8 +686,8 @@ class MessageListView with ChangeNotifier, _MessageSequence {
   void messagesMoved({
     required int origStreamId,
     required int newStreamId,
-    required String origTopic,
-    required String newTopic,
+    required TopicName origTopic,
+    required TopicName newTopic,
     required List<int> messageIds,
     required PropagateMode propagateMode,
   }) {
diff --git a/lib/model/narrow.dart b/lib/model/narrow.dart
index 1553750849..9e29808ceb 100644
--- a/lib/model/narrow.dart
+++ b/lib/model/narrow.dart
@@ -99,7 +99,7 @@ class TopicNarrow extends Narrow implements SendableNarrow {
   }
 
   final int streamId;
-  final String topic;
+  final TopicName topic;
 
   @override
   bool containsMessage(Message message) {
@@ -114,7 +114,7 @@ class TopicNarrow extends Narrow implements SendableNarrow {
   StreamDestination get destination => StreamDestination(streamId, topic);
 
   @override
-  String toString() => 'TopicNarrow($streamId, $topic)';
+  String toString() => 'TopicNarrow($streamId, ${topic.displayName})';
 
   @override
   bool operator ==(Object other) {
diff --git a/lib/model/recent_senders.dart b/lib/model/recent_senders.dart
index d075d05eee..a5c4bca778 100644
--- a/lib/model/recent_senders.dart
+++ b/lib/model/recent_senders.dart
@@ -16,7 +16,7 @@ class RecentSenders {
 
   // topicSenders[streamId][topic][senderId] = MessageIdTracker
   @visibleForTesting
-  final Map<int, Map<String, Map<int, MessageIdTracker>>> topicSenders = {};
+  final Map<int, Map<TopicName, Map<int, MessageIdTracker>>> topicSenders = {};
 
   /// The latest message the given user sent to the given stream,
   /// or null if no such message is known.
@@ -29,7 +29,7 @@ class RecentSenders {
   /// or null if no such message is known.
   int? latestMessageIdOfSenderInTopic({
     required int streamId,
-    required String topic,
+    required TopicName topic,
     required int senderId,
   }) => topicSenders[streamId]?[topic]?[senderId]?.maxId;
 
@@ -38,7 +38,7 @@ class RecentSenders {
   /// The messages must be sorted by [Message.id] ascending.
   void handleMessages(List<Message> messages) {
     final messagesByUserInStream = <(int, int), QueueList<int>>{};
-    final messagesByUserInTopic = <(int, String, int), QueueList<int>>{};
+    final messagesByUserInTopic = <(int, TopicName, int), QueueList<int>>{};
     for (final message in messages) {
       if (message is! StreamMessage) continue;
       final StreamMessage(:streamId, :topic, :senderId, id: int messageId) = message;
diff --git a/lib/model/store.dart b/lib/model/store.dart
index 58a8a70615..7603c7f452 100644
--- a/lib/model/store.dart
+++ b/lib/model/store.dart
@@ -268,6 +268,8 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, ChannelStore, Mess
       globalStore: globalStore,
       connection: connection,
       realmUrl: realmUrl,
+      realmWildcardMentionPolicy: initialSnapshot.realmWildcardMentionPolicy,
+      realmMandatoryTopics: initialSnapshot.realmMandatoryTopics,
       realmWaitingPeriodThreshold: initialSnapshot.realmWaitingPeriodThreshold,
       maxFileUploadSizeMib: initialSnapshot.maxFileUploadSizeMib,
       realmDefaultExternalAccounts: initialSnapshot.realmDefaultExternalAccounts,
@@ -311,6 +313,8 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, ChannelStore, Mess
     required GlobalStore globalStore,
     required this.connection,
     required this.realmUrl,
+    required this.realmWildcardMentionPolicy,
+    required this.realmMandatoryTopics,
     required this.realmWaitingPeriodThreshold,
     required this.maxFileUploadSizeMib,
     required this.realmDefaultExternalAccounts,
@@ -375,6 +379,8 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, ChannelStore, Mess
   Uri? tryResolveUrl(String reference) => _tryResolveUrl(realmUrl, reference);
 
   String get zulipVersion => account.zulipVersion;
+  final RealmWildcardMentionPolicy realmWildcardMentionPolicy; // TODO(#668): update this realm setting
+  final bool realmMandatoryTopics;  // TODO(#668): update this realm setting
   /// For docs, please see [InitialSnapshot.realmWaitingPeriodThreshold].
   final int realmWaitingPeriodThreshold;  // TODO(#668): update this realm setting
   final int maxFileUploadSizeMib; // No event for this.
@@ -466,10 +472,10 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, ChannelStore, Mess
   @override
   Map<int, Subscription> get subscriptions => _channels.subscriptions;
   @override
-  UserTopicVisibilityPolicy topicVisibilityPolicy(int streamId, String topic) =>
+  UserTopicVisibilityPolicy topicVisibilityPolicy(int streamId, TopicName topic) =>
     _channels.topicVisibilityPolicy(streamId, topic);
   @override
-  Map<int, Map<String, UserTopicVisibilityPolicy>> get debugTopicVisibility =>
+  Map<int, Map<TopicName, UserTopicVisibilityPolicy>> get debugTopicVisibility =>
     _channels.debugTopicVisibility;
 
   final ChannelStoreImpl _channels;
@@ -1128,8 +1134,7 @@ class UpdateMachine {
       case Server5xxException():
         shouldReportToUser = true;
 
-      case ServerException(httpStatus: 429):
-      case ZulipApiException(httpStatus: 429):
+      case HttpException(httpStatus: 429):
       case ZulipApiException(code: 'RATE_LIMIT_HIT'):
         // TODO(#946) handle rate-limit errors more generally, in ApiConnection
         shouldReportToUser = true;
diff --git a/lib/model/unreads.dart b/lib/model/unreads.dart
index 4f1ddc603c..1fcea3f83c 100644
--- a/lib/model/unreads.dart
+++ b/lib/model/unreads.dart
@@ -40,7 +40,7 @@ class Unreads extends ChangeNotifier {
     required int selfUserId,
     required ChannelStore channelStore,
   }) {
-    final streams = <int, Map<String, QueueList<int>>>{};
+    final streams = <int, Map<TopicName, QueueList<int>>>{};
     final dms = <DmNarrow, QueueList<int>>{};
     final mentions = Set.of(initial.mentions);
 
@@ -86,7 +86,7 @@ class Unreads extends ChangeNotifier {
   // int count;
 
   /// Unread stream messages, as: stream ID → topic → message IDs (sorted).
-  final Map<int, Map<String, QueueList<int>>> streams;
+  final Map<int, Map<TopicName, QueueList<int>>> streams;
 
   /// Unread DM messages, as: DM narrow → message IDs (sorted).
   final Map<DmNarrow, QueueList<int>> dms;
@@ -185,7 +185,7 @@ class Unreads extends ChangeNotifier {
     return c;
   }
 
-  int countInTopicNarrow(int streamId, String topic) {
+  int countInTopicNarrow(int streamId, TopicName topic) {
     final topics = streams[streamId];
     return topics?[topic]?.length ?? 0;
   }
@@ -365,7 +365,7 @@ class Unreads extends ChangeNotifier {
               _slowRemoveAllInDms(messageIdsSet);
             }
           case UpdateMessageFlagsRemoveEvent():
-            final newlyUnreadInStreams = <int, Map<String, QueueList<int>>>{};
+            final newlyUnreadInStreams = <int, Map<TopicName, QueueList<int>>>{};
             final newlyUnreadInDms = <DmNarrow, QueueList<int>>{};
             for (final messageId in event.messages) {
               final detail = event.messageDetails![messageId];
@@ -449,12 +449,12 @@ class Unreads extends ChangeNotifier {
     );
   }
 
-  void _addLastInStreamTopic(int messageId, int streamId, String topic) {
+  void _addLastInStreamTopic(int messageId, int streamId, TopicName topic) {
     ((streams[streamId] ??= {})[topic] ??= QueueList()).addLast(messageId);
   }
 
   // [messageIds] must be sorted ascending and without duplicates.
-  void _addAllInStreamTopic(QueueList<int> messageIds, int streamId, String topic) {
+  void _addAllInStreamTopic(QueueList<int> messageIds, int streamId, TopicName topic) {
     final topics = streams[streamId] ??= {};
     topics.update(topic,
       ifAbsent: () => messageIds,
@@ -469,7 +469,7 @@ class Unreads extends ChangeNotifier {
   void _slowRemoveAllInStreams(Set<int> idsToRemove) {
     final newlyEmptyStreams = <int>[];
     for (final MapEntry(key: streamId, value: topics) in streams.entries) {
-      final newlyEmptyTopics = <String>[];
+      final newlyEmptyTopics = <TopicName>[];
       for (final MapEntry(key: topic, value: messageIds) in topics.entries) {
         messageIds.removeWhere((id) => idsToRemove.contains(id));
         if (messageIds.isEmpty) {
@@ -488,7 +488,7 @@ class Unreads extends ChangeNotifier {
     }
   }
 
-  void _removeAllInStreamTopic(Set<int> incomingMessageIds, int streamId, String topic) {
+  void _removeAllInStreamTopic(Set<int> incomingMessageIds, int streamId, TopicName topic) {
     final topics = streams[streamId];
     if (topics == null) return;
     final messageIds = topics[topic];
diff --git a/lib/notifications/display.dart b/lib/notifications/display.dart
index 46ea95486a..1d74db6854 100644
--- a/lib/notifications/display.dart
+++ b/lib/notifications/display.dart
@@ -6,6 +6,7 @@ import 'package:collection/collection.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart' hide Notification;
 
+import '../api/model/model.dart';
 import '../api/notifications.dart';
 import '../generated/l10n/zulip_localizations.dart';
 import '../host/android_notifications.dart';
@@ -24,10 +25,11 @@ import '../widgets/theme.dart';
 AndroidNotificationHostApi get _androidHost => ZulipBinding.instance.androidNotificationHost;
 
 enum NotificationSound {
-  // Any new entry here must appear in `keep.xml` too, see #528.
+  // TODO(i18n): translate these file display names
   chime2(resourceName: 'chime2', fileDisplayName: 'Zulip - Low Chime.m4a'),
   chime3(resourceName: 'chime3', fileDisplayName: 'Zulip - Chime.m4a'),
   chime4(resourceName: 'chime4', fileDisplayName: 'Zulip - High Chime.m4a');
+  // Any new entry here must appear in `keep.xml` too, see #528.
 
   const NotificationSound({
     required this.resourceName,
@@ -107,7 +109,7 @@ class NotificationChannelManager {
     // and check against our list of sounds we have.
     final soundsToAdd = NotificationSound.values.toList();
 
-    final List<StoredNotificationSound?> storedSounds;
+    final List<StoredNotificationSound> storedSounds;
     try {
       storedSounds = await _androidHost.listStoredSoundsInNotificationsDirectory();
     } catch (e, st) {
@@ -115,11 +117,9 @@ class NotificationChannelManager {
       return defaultSoundUrl;
     }
     for (final storedSound in storedSounds) {
-      assert(storedSound != null); // TODO(#942)
-
       // If the file is one we put there, and has the name we give to our
       // default sound, then use it as the default sound.
-      if (storedSound!.fileName == kDefaultNotificationSound.fileDisplayName
+      if (storedSound.fileName == kDefaultNotificationSound.fileDisplayName
           && storedSound.isOwned) {
         defaultSoundUrl = storedSound.contentUrl;
       }
@@ -187,8 +187,7 @@ class NotificationChannelManager {
     var found = false;
     final channels = await _androidHost.getNotificationChannels();
     for (final channel in channels) {
-      assert(channel != null); // TODO(#942)
-      if (channel!.id == kChannelId) {
+      if (channel.id == kChannelId) {
         found = true;
       } else {
         await _androidHost.deleteNotificationChannel(channel.id);
@@ -206,7 +205,7 @@ class NotificationChannelManager {
 
     await _androidHost.createNotificationChannel(NotificationChannel(
       id: kChannelId,
-      name: 'Messages', // TODO(i18n)
+      name: 'Messages', // TODO(#1284)
       importance: NotificationImportance.high,
       lightsEnabled: true,
       soundUrl: defaultSoundUrl,
@@ -263,9 +262,9 @@ class NotificationDisplayManager {
     // the first.
     messagingStyle.conversationTitle = switch (data.recipient) {
       FcmMessageChannelRecipient(:var streamName?, :var topic) =>
-        '#$streamName > $topic',
+        '#$streamName > ${topic.displayName}',
       FcmMessageChannelRecipient(:var topic) =>
-        '#(unknown channel) > $topic', // TODO get stream name from data
+        '#${zulipLocalizations.unknownChannelName} > ${topic.displayName}', // TODO get stream name from data
       FcmMessageDmRecipient(:var allRecipientIds) when allRecipientIds.length > 2 =>
         zulipLocalizations.notifGroupDmConversationLabel(
           data.senderFullName, allRecipientIds.length - 2), // TODO use others' names, from data
@@ -377,8 +376,6 @@ class NotificationDisplayManager {
     final activeNotifications = await _androidHost.getActiveNotifications(
       desiredExtras: [kExtraLastZulipMessageId]);
     for (final statusBarNotification in activeNotifications) {
-      if (statusBarNotification == null) continue; // TODO(pigeon) eliminate this case
-
       // The StatusBarNotification object describes an active notification in the UI.
       // Its `.tag`, `.id`, and `.notification` are the same values as we passed to
       // [AndroidNotificationHostApi.notify] (and so to `NotificationManager#notify`
@@ -442,7 +439,7 @@ class NotificationDisplayManager {
 
   static String _conversationKey(MessageFcmMessage data, String groupKey) {
     final conversation = switch (data.recipient) {
-      FcmMessageChannelRecipient(:var streamId, :var topic) => 'stream:$streamId:$topic',
+      FcmMessageChannelRecipient(:var streamId, :var topic) => 'stream:$streamId:${topic.canonicalize()}',
       FcmMessageDmRecipient(:var allRecipientIds) => 'dm:${allRecipientIds.join(',')}',
     };
     return '$groupKey|$conversation';
@@ -456,6 +453,40 @@ class NotificationDisplayManager {
 
   static String _personKey(Uri realmUrl, int userId) => "$realmUrl|$userId";
 
+  /// Provides the route and the account ID by parsing the notification URL.
+  ///
+  /// The URL must have been generated using [NotificationOpenPayload.buildUrl]
+  /// while creating the notification.
+  ///
+  /// Returns null and shows an error dialog if the associated account is not
+  /// found in the global store.
+  static AccountRoute<void>? routeForNotification({
+    required BuildContext context,
+    required Uri url,
+  }) {
+    final globalStore = GlobalStoreWidget.of(context);
+
+    assert(debugLog('got notif: url: $url'));
+    assert(url.scheme == 'zulip' && url.host == 'notification');
+    final payload = NotificationOpenPayload.parseUrl(url);
+
+    final account = globalStore.accounts.firstWhereOrNull(
+      (account) => account.realmUrl.origin == payload.realmUrl.origin
+                && account.userId == payload.userId);
+    if (account == null) { // TODO(log)
+      final zulipLocalizations = ZulipLocalizations.of(context);
+      showErrorDialog(context: context,
+        title: zulipLocalizations.errorNotificationOpenTitle,
+        message: zulipLocalizations.errorNotificationOpenAccountMissing);
+      return null;
+    }
+
+    return MessageListPage.buildRoute(
+      accountId: account.id,
+      // TODO(#82): Open at specific message, not just conversation
+      narrow: payload.narrow);
+  }
+
   /// Navigates to the [MessageListPage] of the specific conversation
   /// given the `zulip://notification/…` Android intent data URL,
   /// generated with [NotificationOpenPayload.buildUrl] while creating
@@ -463,29 +494,16 @@ class NotificationDisplayManager {
   static Future<void> navigateForNotification(Uri url) async {
     assert(debugLog('opened notif: url: $url'));
 
-    assert(url.scheme == 'zulip' && url.host == 'notification');
-    final payload = NotificationOpenPayload.parseUrl(url);
-
     NavigatorState navigator = await ZulipApp.navigator;
     final context = navigator.context;
     assert(context.mounted);
     if (!context.mounted) return; // TODO(linter): this is impossible as there's no actual async gap, but the use_build_context_synchronously lint doesn't see that
 
-    final zulipLocalizations = ZulipLocalizations.of(context);
-    final globalStore = GlobalStoreWidget.of(context);
-    final account = globalStore.accounts.firstWhereOrNull((account) =>
-      account.realmUrl == payload.realmUrl && account.userId == payload.userId);
-    if (account == null) { // TODO(log)
-      showErrorDialog(context: context,
-        title: zulipLocalizations.errorNotificationOpenTitle,
-        message: zulipLocalizations.errorNotificationOpenAccountMissing);
-      return;
-    }
+    final route = routeForNotification(context: context, url: url);
+    if (route == null) return; // TODO(log)
 
     // TODO(nav): Better interact with existing nav stack on notif open
-    unawaited(navigator.push(MaterialAccountWidgetRoute<void>(accountId: account.id,
-      // TODO(#82): Open at specific message, not just conversation
-      page: MessageListPage(initNarrow: payload.narrow))));
+    unawaited(navigator.push(route));
   }
 
   static Future<Uint8List?> _fetchBitmap(Uri url) async {
@@ -538,8 +556,8 @@ class NotificationOpenPayload {
         case 'topic':
           final channelIdStr = url.queryParameters['channel_id']!;
           final channelId = int.parse(channelIdStr, radix: 10);
-          final topic = url.queryParameters['topic']!;
-          narrow = TopicNarrow(channelId, topic);
+          final topicStr = url.queryParameters['topic']!;
+          narrow = TopicNarrow(channelId, TopicName(topicStr));
         case 'dm':
           final allRecipientIdsStr = url.queryParameters['all_recipient_ids']!;
           final allRecipientIds = allRecipientIdsStr.split(',')
@@ -572,7 +590,7 @@ class NotificationOpenPayload {
           TopicNarrow(streamId: var channelId, :var topic) => {
             'narrow_type': 'topic',
             'channel_id': channelId.toString(),
-            'topic': topic,
+            'topic': topic.apiName,
           },
           DmNarrow(:var allRecipientIds) => {
             'narrow_type': 'dm',
diff --git a/lib/widgets/about_zulip.dart b/lib/widgets/about_zulip.dart
index d0c1c8d29e..8abfa97c49 100644
--- a/lib/widgets/about_zulip.dart
+++ b/lib/widgets/about_zulip.dart
@@ -43,7 +43,8 @@ class _AboutZulipPageState extends State<AboutZulipPage> {
               child: Column(mainAxisAlignment: MainAxisAlignment.center, children: [
                 ListTile(
                   title: Text(zulipLocalizations.aboutPageAppVersion),
-                  subtitle: Text(_packageInfo?.version ?? '(…)')),
+                  subtitle: Text(_packageInfo?.version
+                    ?? zulipLocalizations.appVersionUnknownPlaceholder)),
                 ListTile(
                   title: Text(zulipLocalizations.aboutPageOpenSourceLicenses),
                   subtitle: Text(zulipLocalizations.aboutPageTapToView),
diff --git a/lib/widgets/action_sheet.dart b/lib/widgets/action_sheet.dart
index fca61d4810..7c3ea6e622 100644
--- a/lib/widgets/action_sheet.dart
+++ b/lib/widgets/action_sheet.dart
@@ -24,6 +24,7 @@ import 'emoji_reaction.dart';
 import 'icons.dart';
 import 'inset_shadow.dart';
 import 'message_list.dart';
+import 'page.dart';
 import 'store.dart';
 import 'text.dart';
 import 'theme.dart';
@@ -64,6 +65,20 @@ void _showActionSheet(
     });
 }
 
+/// A button in an action sheet.
+///
+/// When built from server data, the action sheet ignores changes in that data;
+/// we intentionally don't live-update the buttons on events.
+/// If a button's label, action, or position changes suddenly,
+/// it can be confusing and make the on-tap behavior unexpected.
+/// Better to let the user decide to tap
+/// based on information that's comfortably in their working memory,
+/// even if we sometimes have to explain (where we handle the tap)
+/// that that information has changed and they need to decide again.
+///
+/// (Even if we did live-update the buttons, it's possible anyway that a user's
+/// action can race with a change that's already been applied on the server,
+/// because it takes some time for the server to report changes to us.)
 abstract class ActionSheetMenuItemButton extends StatelessWidget {
   const ActionSheetMenuItemButton({super.key, required this.pageContext});
 
@@ -149,11 +164,19 @@ class ActionSheetCancelButton extends StatelessWidget {
 }
 
 /// Show a sheet of actions you can take on a topic.
+///
+/// Needs a [PageRoot] ancestor.
+///
+/// The API request for resolving/unresolving a topic needs a message ID.
+/// If [someMessageIdInTopic] is null, the button for that will be absent.
 void showTopicActionSheet(BuildContext context, {
   required int channelId,
-  required String topic,
+  required TopicName topic,
+  required int? someMessageIdInTopic,
 }) {
-  final store = PerAccountStoreWidget.of(context);
+  final pageContext = PageRoot.contextOf(context);
+
+  final store = PerAccountStoreWidget.of(pageContext);
   final subscription = store.subscriptions[channelId];
 
   final optionButtons = <ActionSheetMenuItemButton>[];
@@ -223,9 +246,15 @@ void showTopicActionSheet(BuildContext context, {
       currentVisibilityPolicy: visibilityPolicy,
       newVisibilityPolicy: to,
       narrow: TopicNarrow(channelId, topic),
-      pageContext: context);
+      pageContext: pageContext);
   }));
 
+  if (someMessageIdInTopic != null) {
+    optionButtons.add(ResolveUnresolveButton(pageContext: pageContext,
+      topic: topic,
+      someMessageIdInTopic: someMessageIdInTopic));
+  }
+
   if (optionButtons.isEmpty) {
     // TODO(a11y): This case makes a no-op gesture handler; as a consequence,
     //   we're presenting some UI (to people who use screen-reader software) as
@@ -236,7 +265,7 @@ void showTopicActionSheet(BuildContext context, {
     return;
   }
 
-  _showActionSheet(context, optionButtons: optionButtons);
+  _showActionSheet(pageContext, optionButtons: optionButtons);
 }
 
 class UserTopicUpdateButton extends ActionSheetMenuItemButton {
@@ -358,18 +387,93 @@ class UserTopicUpdateButton extends ActionSheetMenuItemButton {
   }
 }
 
+class ResolveUnresolveButton extends ActionSheetMenuItemButton {
+  ResolveUnresolveButton({
+    super.key,
+    required this.topic,
+    required this.someMessageIdInTopic,
+    required super.pageContext,
+  }) : _actionIsResolve = !topic.isResolved;
+
+  /// The topic that the action sheet was opened for.
+  ///
+  /// There might not currently be any messages with this topic;
+  /// see dartdoc of [ActionSheetMenuItemButton].
+  final TopicName topic;
+
+  /// The message ID that was passed when opening the action sheet.
+  ///
+  /// The message with this ID might currently not exist,
+  /// or might exist with a different topic;
+  /// see dartdoc of [ActionSheetMenuItemButton].
+  final int someMessageIdInTopic;
+
+  final bool _actionIsResolve;
+
+  @override
+  IconData get icon => _actionIsResolve ? ZulipIcons.check : ZulipIcons.check_remove;
+
+  @override
+  String label(ZulipLocalizations zulipLocalizations) {
+    return _actionIsResolve
+      ? zulipLocalizations.actionSheetOptionResolveTopic
+      : zulipLocalizations.actionSheetOptionUnresolveTopic;
+  }
+
+  @override void onPressed() async {
+    final zulipLocalizations = ZulipLocalizations.of(pageContext);
+    final store = PerAccountStoreWidget.of(pageContext);
+
+    // We *could* check here if the topic has changed since the action sheet was
+    // opened (see dartdoc of [ActionSheetMenuItemButton]) and abort if so.
+    // We simplify by not doing so.
+    // There's already an inherent race that that check wouldn't help with:
+    // when you tap the button, an intervening topic change may already have
+    // happened, just not reached us in an event yet.
+    // Discussion, including about what web does:
+    //   https://github.com/zulip/zulip-flutter/pull/1301#discussion_r1936181560
+
+    try {
+      await updateMessage(store.connection,
+        messageId: someMessageIdInTopic,
+        topic: _actionIsResolve ? topic.resolve() : topic.unresolve(),
+        propagateMode: PropagateMode.changeAll,
+        sendNotificationToOldThread: false,
+        sendNotificationToNewThread: true,
+      );
+    } catch (e) {
+      if (!pageContext.mounted) return;
+
+      String? errorMessage;
+      switch (e) {
+        case ZulipApiException():
+          errorMessage = e.message;
+          // TODO(#741) specific messages for common errors, like network errors
+          //   (support with reusable code)
+        default:
+      }
+
+      final title = _actionIsResolve
+        ? zulipLocalizations.errorResolveTopicFailedTitle
+        : zulipLocalizations.errorUnresolveTopicFailedTitle;
+      showErrorDialog(context: pageContext, title: title, message: errorMessage);
+    }
+  }
+}
+
 /// Show a sheet of actions you can take on a message in the message list.
 ///
 /// Must have a [MessageListPage] ancestor.
 void showMessageActionSheet({required BuildContext context, required Message message}) {
-  final store = PerAccountStoreWidget.of(context);
+  final pageContext = PageRoot.contextOf(context);
+  final store = PerAccountStoreWidget.of(pageContext);
 
   // The UI that's conditioned on this won't live-update during this appearance
   // of the action sheet (we avoid calling composeBoxControllerOf in a build
   // method; see its doc).
   // So we rely on the fact that isComposeBoxOffered for any given message list
   // will be constant through the page's life.
-  final messageListPage = MessageListPage.ancestorOf(context);
+  final messageListPage = MessageListPage.ancestorOf(pageContext);
   final isComposeBoxOffered = messageListPage.composeBoxController != null;
 
   final isMessageRead = message.flags.contains(MessageFlag.read);
@@ -377,18 +481,18 @@ void showMessageActionSheet({required BuildContext context, required Message mes
   final showMarkAsUnreadButton = markAsUnreadSupported && isMessageRead;
 
   final optionButtons = [
-    ReactionButtons(message: message, pageContext: context),
-    StarButton(message: message, pageContext: context),
+    ReactionButtons(message: message, pageContext: pageContext),
+    StarButton(message: message, pageContext: pageContext),
     if (isComposeBoxOffered)
-      QuoteAndReplyButton(message: message, pageContext: context),
+      QuoteAndReplyButton(message: message, pageContext: pageContext),
     if (showMarkAsUnreadButton)
-      MarkAsUnreadButton(message: message, pageContext: context),
-    CopyMessageTextButton(message: message, pageContext: context),
-    CopyMessageLinkButton(message: message, pageContext: context),
-    ShareButton(message: message, pageContext: context),
+      MarkAsUnreadButton(message: message, pageContext: pageContext),
+    CopyMessageTextButton(message: message, pageContext: pageContext),
+    CopyMessageLinkButton(message: message, pageContext: pageContext),
+    ShareButton(message: message, pageContext: pageContext),
   ];
 
-  _showActionSheet(context, optionButtons: optionButtons);
+  _showActionSheet(pageContext, optionButtons: optionButtons);
 }
 
 abstract class MessageActionSheetMenuItemButton extends ActionSheetMenuItemButton {
@@ -633,6 +737,7 @@ class QuoteAndReplyButton extends MessageActionSheetMenuItemButton {
 
   @override void onPressed() async {
     final zulipLocalizations = ZulipLocalizations.of(pageContext);
+    final message = this.message;
 
     var composeBoxController = findMessageListPage().composeBoxController;
     // The compose box doesn't null out its controller; it's either always null
@@ -644,13 +749,15 @@ class QuoteAndReplyButton extends MessageActionSheetMenuItemButton {
       && composeBoxController.topic.textNormalized == kNoTopicTopic
       && message is StreamMessage
     ) {
-      composeBoxController.topic.value = TextEditingValue(text: message.topic);
+      composeBoxController.topic.setTopic(message.topic);
     }
 
     // This inserts a "[Quoting…]" placeholder into the content input,
     // giving the user a form of progress feedback.
     final tag = composeBoxController.content
-      .registerQuoteAndReplyStart(PerAccountStoreWidget.of(pageContext),
+      .registerQuoteAndReplyStart(
+        zulipLocalizations,
+        PerAccountStoreWidget.of(pageContext),
         message: message,
       );
 
diff --git a/lib/widgets/app.dart b/lib/widgets/app.dart
index 75fec7bc8b..9fa82144a1 100644
--- a/lib/widgets/app.dart
+++ b/lib/widgets/app.dart
@@ -139,6 +139,52 @@ class ZulipApp extends StatefulWidget {
 }
 
 class _ZulipAppState extends State<ZulipApp> with WidgetsBindingObserver {
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addObserver(this);
+  }
+
+  @override
+  void dispose() {
+    WidgetsBinding.instance.removeObserver(this);
+    super.dispose();
+  }
+
+  List<Route<dynamic>> _handleGenerateInitialRoutes(String initialRoute) {
+    // The `_ZulipAppState.context` lacks the required ancestors. Instead
+    // we use the Navigator which should be available when this callback is
+    // called and it's context should have the required ancestors.
+    final context = ZulipApp.navigatorKey.currentContext!;
+
+    final initialRouteUrl = Uri.tryParse(initialRoute);
+    if (initialRouteUrl case Uri(scheme: 'zulip', host: 'notification')) {
+      final route = NotificationDisplayManager.routeForNotification(
+        context: context,
+        url: initialRouteUrl);
+
+      if (route != null) {
+        return [
+          HomePage.buildRoute(accountId: route.accountId),
+          route,
+        ];
+      } else {
+        // The account didn't match any existing accounts,
+        // fall through to show the default route below.
+      }
+    }
+
+    final globalStore = GlobalStoreWidget.of(context);
+    // TODO(#524) choose initial account as last one used
+    final initialAccountId = globalStore.accounts.firstOrNull?.id;
+    return [
+      if (initialAccountId == null)
+        MaterialWidgetRoute(page: const ChooseAccountPage())
+      else
+        HomePage.buildRoute(accountId: initialAccountId),
+    ];
+  }
+
   @override
   Future<bool> didPushRouteInformation(routeInformation) async {
     switch (routeInformation.uri) {
@@ -152,69 +198,39 @@ class _ZulipAppState extends State<ZulipApp> with WidgetsBindingObserver {
     return super.didPushRouteInformation(routeInformation);
   }
 
-  Future<void> _handleInitialRoute() async {
-    final initialRouteUrl = Uri.parse(WidgetsBinding.instance.platformDispatcher.defaultRouteName);
-    if (initialRouteUrl case Uri(scheme: 'zulip', host: 'notification')) {
-      await NotificationDisplayManager.navigateForNotification(initialRouteUrl);
-    }
-  }
-
-  @override
-  void initState() {
-    super.initState();
-    WidgetsBinding.instance.addObserver(this);
-    _handleInitialRoute();
-  }
-
-  @override
-  void dispose() {
-    WidgetsBinding.instance.removeObserver(this);
-    super.dispose();
-  }
-
   @override
   Widget build(BuildContext context) {
     final themeData = zulipThemeData(context);
     return GlobalStoreWidget(
-      child: Builder(builder: (context) {
-        final globalStore = GlobalStoreWidget.of(context);
-        // TODO(#524) choose initial account as last one used
-        final initialAccountId = globalStore.accounts.firstOrNull?.id;
-        return MaterialApp(
-          title: 'Zulip',
-          localizationsDelegates: ZulipLocalizations.localizationsDelegates,
-          supportedLocales: ZulipLocalizations.supportedLocales,
-          theme: themeData,
-
-          navigatorKey: ZulipApp.navigatorKey,
-          navigatorObservers: widget.navigatorObservers ?? const [],
-          builder: (BuildContext context, Widget? child) {
-            if (!ZulipApp.ready.value) {
-              SchedulerBinding.instance.addPostFrameCallback(
-                (_) => widget._declareReady());
-            }
-            GlobalLocalizations.zulipLocalizations = ZulipLocalizations.of(context);
-            return child!;
-          },
-
-          // We use onGenerateInitialRoutes for the real work of specifying the
-          // initial nav state.  To do that we need [MaterialApp] to decide to
-          // build a [Navigator]... which means specifying either `home`, `routes`,
-          // `onGenerateRoute`, or `onUnknownRoute`.  Make it `onGenerateRoute`.
-          // It never actually gets called, though: `onGenerateInitialRoutes`
-          // handles startup, and then we always push whole routes with methods
-          // like [Navigator.push], never mere names as with [Navigator.pushNamed].
-          onGenerateRoute: (_) => null,
-
-          onGenerateInitialRoutes: (_) {
-            return [
-              if (initialAccountId == null)
-                MaterialWidgetRoute(page: const ChooseAccountPage())
-              else
-                HomePage.buildRoute(accountId: initialAccountId),
-            ];
-          });
-        }));
+      child: MaterialApp(
+        onGenerateTitle: (BuildContext context) {
+          return ZulipLocalizations.of(context).zulipAppTitle;
+        },
+        localizationsDelegates: ZulipLocalizations.localizationsDelegates,
+        supportedLocales: ZulipLocalizations.supportedLocales,
+        theme: themeData,
+
+        navigatorKey: ZulipApp.navigatorKey,
+        navigatorObservers: widget.navigatorObservers ?? const [],
+        builder: (BuildContext context, Widget? child) {
+          if (!ZulipApp.ready.value) {
+            SchedulerBinding.instance.addPostFrameCallback(
+              (_) => widget._declareReady());
+          }
+          GlobalLocalizations.zulipLocalizations = ZulipLocalizations.of(context);
+          return child!;
+        },
+
+        // We use onGenerateInitialRoutes for the real work of specifying the
+        // initial nav state.  To do that we need [MaterialApp] to decide to
+        // build a [Navigator]... which means specifying either `home`, `routes`,
+        // `onGenerateRoute`, or `onUnknownRoute`.  Make it `onGenerateRoute`.
+        // It never actually gets called, though: `onGenerateInitialRoutes`
+        // handles startup, and then we always push whole routes with methods
+        // like [Navigator.push], never mere names as with [Navigator.pushNamed].
+        onGenerateRoute: (_) => null,
+
+        onGenerateInitialRoutes: _handleGenerateInitialRoutes));
   }
 }
 
@@ -323,6 +339,7 @@ class ChooseAccountPageOverflowButton extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final zulipLocalizations = ZulipLocalizations.of(context);
     final materialLocalizations = MaterialLocalizations.of(context);
     return MenuAnchor(
       menuChildren: [
@@ -330,7 +347,7 @@ class ChooseAccountPageOverflowButton extends StatelessWidget {
           onPressed: () {
             Navigator.push(context, AboutZulipPage.buildRoute(context));
           },
-          child: const Text('About Zulip')), // TODO(i18n)
+          child: Text(zulipLocalizations.aboutPageTitle)),
       ],
       builder: (BuildContext context, MenuController controller, Widget? child) {
         return IconButton(
diff --git a/lib/widgets/app_bar.dart b/lib/widgets/app_bar.dart
index a69e71f7fa..f548557681 100644
--- a/lib/widgets/app_bar.dart
+++ b/lib/widgets/app_bar.dart
@@ -6,14 +6,66 @@ import 'store.dart';
 ///
 /// This should be used for most of the pages with access to [PerAccountStore].
 class ZulipAppBar extends AppBar {
+  /// Creates our Zulip custom app bar based on [AppBar].
+  ///
+  /// [buildTitle] is passed a boolean `willCenterTitle` that answers
+  /// whether the underlying [AppBar] will decide to center [title]
+  /// based on [centerTitle], the theme, the platform, and [actions].
+  /// Useful if [title] is a container whose children should align the same way,
+  /// such as a [Column] with multiple lines of text.
+  // TODO(upstream) send a PR to replace our `willCenterTitle` code
   ZulipAppBar({
     super.key,
     super.titleSpacing,
-    required super.title,
+    Widget? title,
+    Widget Function(bool willCenterTitle)? buildTitle,
+    super.centerTitle,
     super.backgroundColor,
     super.shape,
     super.actions,
-  }) : super(bottom: _ZulipAppBarBottom(backgroundColor: backgroundColor));
+  }) :
+    assert((title == null) != (buildTitle == null)),
+    super(
+      bottom: _ZulipAppBarBottom(backgroundColor: backgroundColor),
+      title: title ?? _Title(centerTitle: centerTitle, actions: actions, buildTitle: buildTitle!)
+    );
+}
+
+class _Title extends StatelessWidget {
+  const _Title({
+    required this.centerTitle,
+    required this.actions,
+    required this.buildTitle,
+  });
+
+  final bool? centerTitle;
+  final List<Widget>? actions;
+  final Widget Function(bool centerTitle) buildTitle;
+
+  // A copy of [AppBar._getEffectiveCenterTitle].
+  bool _getEffectiveCenterTitle(ThemeData theme) {
+    bool platformCenter() {
+      switch (theme.platform) {
+        case TargetPlatform.android:
+        case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
+          return false;
+        case TargetPlatform.iOS:
+        case TargetPlatform.macOS:
+          return actions == null || actions!.length < 2;
+      }
+    }
+
+    return centerTitle ?? theme.appBarTheme.centerTitle ?? platformCenter();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final willCenterTitle = _getEffectiveCenterTitle(theme);
+    return buildTitle(willCenterTitle);
+  }
 }
 
 class _ZulipAppBarBottom extends StatelessWidget implements PreferredSizeWidget {
diff --git a/lib/widgets/autocomplete.dart b/lib/widgets/autocomplete.dart
index a1e5289b01..40d1f2bf16 100644
--- a/lib/widgets/autocomplete.dart
+++ b/lib/widgets/autocomplete.dart
@@ -1,8 +1,11 @@
 import 'package:flutter/material.dart';
 
+import '../generated/l10n/zulip_localizations.dart';
 import '../model/emoji.dart';
+import '../model/store.dart';
 import 'content.dart';
 import 'emoji.dart';
+import 'icons.dart';
 import 'store.dart';
 import '../model/autocomplete.dart';
 import '../model/compose.dart';
@@ -173,7 +176,9 @@ class ComposeAutocomplete extends AutocompleteField<ComposeAutocompleteQuery, Co
   @override
   ComposeAutocompleteView initViewModel(BuildContext context, ComposeAutocompleteQuery query) {
     final store = PerAccountStoreWidget.of(context);
-    return query.initViewModel(store, narrow);
+    final localizations = ZulipLocalizations.of(context);
+    return query.initViewModel(store: store, localizations: localizations,
+      narrow: narrow);
   }
 
   void _onTapOption(BuildContext context, ComposeAutocompleteResult option) {
@@ -197,7 +202,9 @@ class ComposeAutocomplete extends AutocompleteField<ComposeAutocompleteQuery, Co
         }
         // TODO(i18n) language-appropriate space character; check active keyboard?
         //   (maybe handle centrally in `controller`)
-        replacementString = '${mention(store.users[userId]!, silent: query.silent, users: store.users)} ';
+        replacementString = '${userMention(store.users[userId]!, silent: query.silent, users: store.users)} ';
+      case WildcardMentionAutocompleteResult(:var wildcardOption):
+        replacementString = '${wildcardMention(wildcardOption, store: store)} ';
     }
 
     controller.value = intent.textEditingValue.replaced(
@@ -211,7 +218,8 @@ class ComposeAutocomplete extends AutocompleteField<ComposeAutocompleteQuery, Co
   @override
   Widget buildItem(BuildContext context, int index, ComposeAutocompleteResult option) {
     final child = switch (option) {
-      MentionAutocompleteResult() => _MentionAutocompleteItem(option: option),
+      MentionAutocompleteResult() => _MentionAutocompleteItem(
+        option: option, narrow: narrow),
       EmojiAutocompleteResult() => _EmojiAutocompleteItem(option: option),
     };
     return InkWell(
@@ -223,18 +231,47 @@ class ComposeAutocomplete extends AutocompleteField<ComposeAutocompleteQuery, Co
 }
 
 class _MentionAutocompleteItem extends StatelessWidget {
-  const _MentionAutocompleteItem({required this.option});
+  const _MentionAutocompleteItem({required this.option, required this.narrow});
 
   final MentionAutocompleteResult option;
+  final Narrow narrow;
+
+  Widget wildcardLabel(WildcardMentionOption wildcardOption, {
+    required BuildContext context,
+    required PerAccountStore store,
+  }) {
+    final isDmNarrow = narrow is DmNarrow;
+    final isChannelWildcardAvailable = store.account.zulipFeatureLevel >= 247; // TODO(server-9)
+    final localizations = ZulipLocalizations.of(context);
+    final description = switch (wildcardOption) {
+      WildcardMentionOption.all || WildcardMentionOption.everyone => isDmNarrow
+        ? localizations.wildcardMentionAllDmDescription
+        : isChannelWildcardAvailable
+            ? localizations.wildcardMentionChannelDescription
+            : localizations.wildcardMentionStreamDescription,
+      WildcardMentionOption.channel => localizations.wildcardMentionChannelDescription,
+      WildcardMentionOption.stream => isChannelWildcardAvailable
+        ? localizations.wildcardMentionChannelDescription
+        : localizations.wildcardMentionStreamDescription,
+      WildcardMentionOption.topic => localizations.wildcardMentionTopicDescription,
+    };
+    return Text.rich(TextSpan(text: '${wildcardOption.canonicalString} ', children: [
+      TextSpan(text: description, style: TextStyle(fontSize: 12,
+        color: DefaultTextStyle.of(context).style.color?.withValues(alpha: 0.8)))]));
+  }
 
   @override
   Widget build(BuildContext context) {
+    final store = PerAccountStoreWidget.of(context);
     Widget avatar;
-    String label;
+    Widget label;
     switch (option) {
       case UserMentionAutocompleteResult(:var userId):
-        avatar = Avatar(userId: userId, size: 32, borderRadius: 3);
-        label = PerAccountStoreWidget.of(context).users[userId]!.fullName;
+        avatar = Avatar(userId: userId, size: 32, borderRadius: 3); // web uses 21px
+        label = Text(store.users[userId]!.fullName);
+      case WildcardMentionAutocompleteResult(:var wildcardOption):
+        avatar = const Icon(ZulipIcons.three_person, size: 29); // web uses 19px
+        label = wildcardLabel(wildcardOption, context: context, store: store);
     }
 
     return Padding(
@@ -242,7 +279,7 @@ class _MentionAutocompleteItem extends StatelessWidget {
       child: Row(children: [
         avatar,
         const SizedBox(width: 8),
-        Text(label),
+        label,
       ]));
   }
 }
@@ -321,13 +358,8 @@ class TopicAutocomplete extends AutocompleteField<TopicAutocompleteQuery, TopicA
   void _onTapOption(BuildContext context, TopicAutocompleteResult option) {
     final intent = autocompleteIntent();
     if (intent == null) return;
-    final replacementString = option.topic;
-    controller.value = intent.textEditingValue.replaced(
-      TextRange(
-        start: intent.syntaxStart,
-        end: intent.textEditingValue.text.length),
-      replacementString,
-    );
+    assert(intent.syntaxStart == 0);
+    controller.setTopic(option.topic);
     contentFocusNode.requestFocus();
   }
 
@@ -339,6 +371,6 @@ class TopicAutocomplete extends AutocompleteField<TopicAutocompleteQuery, TopicA
       },
       child: Padding(
         padding: const EdgeInsets.symmetric(horizontal: 16.0, vertical: 8.0),
-        child: Text(option.topic)));
+        child: Text(option.topic.displayName)));
   }
 }
diff --git a/lib/widgets/compose_box.dart b/lib/widgets/compose_box.dart
index 114e392bc7..2b1756e4fe 100644
--- a/lib/widgets/compose_box.dart
+++ b/lib/widgets/compose_box.dart
@@ -22,16 +22,90 @@ import 'store.dart';
 import 'text.dart';
 import 'theme.dart';
 
+/// Compose-box styles that differ between light and dark theme.
+///
+/// These styles will animate on theme changes (with help from [lerp]).
+class ComposeBoxTheme extends ThemeExtension<ComposeBoxTheme> {
+  static final light = ComposeBoxTheme._(
+    boxShadow: null,
+  );
+
+  static final dark = ComposeBoxTheme._(
+    boxShadow: [BoxShadow(
+      color: DesignVariables.dark.bgTopBar,
+      offset: const Offset(0, -4),
+      blurRadius: 16,
+      spreadRadius: 0,
+    )],
+  );
+
+  ComposeBoxTheme._({
+    required this.boxShadow,
+  });
+
+  /// The [ComposeBoxTheme] from the context's active theme.
+  ///
+  /// The [ThemeData] must include [ComposeBoxTheme] in [ThemeData.extensions].
+  static ComposeBoxTheme of(BuildContext context) {
+    final theme = Theme.of(context);
+    final extension = theme.extension<ComposeBoxTheme>();
+    assert(extension != null);
+    return extension!;
+  }
+
+  final List<BoxShadow>? boxShadow;
+
+  @override
+  ComposeBoxTheme copyWith({
+    List<BoxShadow>? boxShadow,
+  }) {
+    return ComposeBoxTheme._(
+      boxShadow: boxShadow ?? this.boxShadow,
+    );
+  }
+
+  @override
+  ComposeBoxTheme lerp(ComposeBoxTheme other, double t) {
+    if (identical(this, other)) {
+      return this;
+    }
+    return ComposeBoxTheme._(
+      boxShadow: BoxShadow.lerpList(boxShadow, other.boxShadow, t)!,
+    );
+  }
+}
+
 const double _composeButtonSize = 44;
 
 /// A [TextEditingController] for use in the compose box.
 ///
 /// Subclasses must ensure that [_update] is called in all exposed constructors.
 abstract class ComposeController<ErrorT> extends TextEditingController {
+  int get maxLengthUnicodeCodePoints;
+
   String get textNormalized => _textNormalized;
   late String _textNormalized;
   String _computeTextNormalized();
 
+  /// Length of [textNormalized] in Unicode code points
+  /// if it might exceed [maxLengthUnicodeCodePoints], else null.
+  ///
+  /// Use this instead of [String.length]
+  /// to enforce a max length expressed in code points.
+  /// [String.length] is conservative and may cut the user off too short.
+  ///
+  /// Counting code points ([String.runes])
+  /// is more expensive than getting the number of UTF-16 code units
+  /// ([String.length]), so we avoid it when the result definitely won't exceed
+  /// [maxLengthUnicodeCodePoints].
+  late int? _lengthUnicodeCodePointsIfLong;
+  @visibleForTesting
+  int? get debugLengthUnicodeCodePointsIfLong => _lengthUnicodeCodePointsIfLong;
+  int? _computeLengthUnicodeCodePointsIfLong() =>
+    _textNormalized.length > maxLengthUnicodeCodePoints
+      ? _textNormalized.runes.length
+      : null;
+
   List<ErrorT> get validationErrors => _validationErrors;
   late List<ErrorT> _validationErrors;
   List<ErrorT> _computeValidationErrors();
@@ -40,6 +114,8 @@ abstract class ComposeController<ErrorT> extends TextEditingController {
 
   void _update() {
     _textNormalized = _computeTextNormalized();
+    // uses _textNormalized, so comes after _computeTextNormalized()
+    _lengthUnicodeCodePointsIfLong = _computeLengthUnicodeCodePointsIfLong();
     _validationErrors = _computeValidationErrors();
     hasValidationErrors.value = _validationErrors.isNotEmpty;
   }
@@ -66,13 +142,17 @@ enum TopicValidationError {
 }
 
 class ComposeTopicController extends ComposeController<TopicValidationError> {
-  ComposeTopicController() {
+  ComposeTopicController({required this.store}) {
     _update();
   }
 
-  // TODO: subscribe to this value:
-  //   https://zulip.com/help/require-topics
-  final mandatory = true;
+  PerAccountStore store;
+
+  // TODO(#668): listen to [PerAccountStore] once we subscribe to this value
+  bool get mandatory => store.realmMandatoryTopics;
+
+  // TODO(#307) use `max_topic_length` instead of hardcoded limit
+  @override final maxLengthUnicodeCodePoints = kMaxTopicLengthCodePoints;
 
   @override
   String _computeTextNormalized() {
@@ -85,10 +165,18 @@ class ComposeTopicController extends ComposeController<TopicValidationError> {
     return [
       if (mandatory && textNormalized == kNoTopicTopic)
         TopicValidationError.mandatoryButEmpty,
-      if (textNormalized.length > kMaxTopicLength)
+
+      if (
+        _lengthUnicodeCodePointsIfLong != null
+        && _lengthUnicodeCodePointsIfLong! > maxLengthUnicodeCodePoints
+      )
         TopicValidationError.tooLong,
     ];
   }
+
+  void setTopic(TopicName newTopic) {
+    value = TextEditingValue(text: newTopic.displayName);
+  }
 }
 
 enum ContentValidationError {
@@ -116,6 +204,9 @@ class ComposeContentController extends ComposeController<ContentValidationError>
     _update();
   }
 
+  // TODO(#1237) use `max_message_length` instead of hardcoded limit
+  @override final maxLengthUnicodeCodePoints = kMaxMessageLengthCodePoints;
+
   int _nextQuoteAndReplyTag = 0;
   int _nextUploadTag = 0;
 
@@ -175,10 +266,15 @@ class ComposeContentController extends ComposeController<ContentValidationError>
   ///
   /// Returns an int "tag" that should be passed to registerQuoteAndReplyEnd on
   /// success or failure
-  int registerQuoteAndReplyStart(PerAccountStore store, {required Message message}) {
+  int registerQuoteAndReplyStart(
+    ZulipLocalizations zulipLocalizations,
+    PerAccountStore store, {
+      required Message message,
+    }) {
     final tag = _nextQuoteAndReplyTag;
     _nextQuoteAndReplyTag += 1;
-    final placeholder = quoteAndReplyPlaceholder(store, message: message);
+    final placeholder = quoteAndReplyPlaceholder(
+      zulipLocalizations, store, message: message);
     _quoteAndReplies[tag] = (messageId: message.id, placeholder: placeholder);
     notifyListeners(); // _quoteAndReplies change could affect validationErrors
     insertPadded(placeholder);
@@ -257,10 +353,10 @@ class ComposeContentController extends ComposeController<ContentValidationError>
       if (textNormalized.isEmpty)
         ContentValidationError.empty,
 
-      // normalized.length is the number of UTF-16 code units, while the server
-      // API expresses the max in Unicode code points. So this comparison will
-      // be conservative and may cut the user off shorter than necessary.
-      if (textNormalized.length > kMaxMessageLengthCodePoints)
+      if (
+        _lengthUnicodeCodePointsIfLong != null
+        && _lengthUnicodeCodePointsIfLong! > maxLengthUnicodeCodePoints
+      )
         ContentValidationError.tooLong,
 
       if (_quoteAndReplies.isNotEmpty)
@@ -483,10 +579,10 @@ class _StreamContentInputState extends State<_StreamContentInput> {
     final store = PerAccountStoreWidget.of(context);
     final zulipLocalizations = ZulipLocalizations.of(context);
     final streamName = store.streams[widget.narrow.streamId]?.name
-      ?? zulipLocalizations.composeBoxUnknownChannelName;
+      ?? zulipLocalizations.unknownChannelName;
     return _ContentInput(
       narrow: widget.narrow,
-      destination: TopicNarrow(widget.narrow.streamId, _topicTextNormalized),
+      destination: TopicNarrow(widget.narrow.streamId, TopicName(_topicTextNormalized)),
       controller: widget.controller,
       hintText: zulipLocalizations.composeBoxChannelContentHint(streamName, _topicTextNormalized));
   }
@@ -545,8 +641,9 @@ class _FixedDestinationContentInput extends StatelessWidget {
       case TopicNarrow(:final streamId, :final topic):
         final store = PerAccountStoreWidget.of(context);
         final streamName = store.streams[streamId]?.name
-          ?? zulipLocalizations.composeBoxUnknownChannelName;
-        return zulipLocalizations.composeBoxChannelContentHint(streamName, topic);
+          ?? zulipLocalizations.unknownChannelName;
+        return zulipLocalizations.composeBoxChannelContentHint(
+          streamName, topic.displayName);
 
       case DmNarrow(otherRecipientIds: []): // The self-1:1 thread.
         return zulipLocalizations.composeBoxSelfDmContentHint;
@@ -612,7 +709,8 @@ Future<void> _uploadFiles({
 
   if (tooLargeFiles.isNotEmpty) {
     final listMessage = tooLargeFiles
-      .map((file) => '${file.filename}: ${(file.length / (1 << 20)).toStringAsFixed(1)} MiB')
+      .map((file) => zulipLocalizations.filenameAndSizeInMiB(
+        file.filename, (file.length / (1 << 20)).toStringAsFixed(1)))
       .join('\n');
     showErrorDialog(
       context: context,
@@ -1048,10 +1146,12 @@ class _ComposeBoxContainer extends StatelessWidget {
     };
 
     // TODO(design): Maybe put a max width on the compose box, like we do on
-    //   the message list itself
+    //   the message list itself; if so, remember to update ComposeBox's dartdoc.
     return Container(width: double.infinity,
       decoration: BoxDecoration(
-        border: Border(top: BorderSide(color: designVariables.borderBar))),
+        border: Border(top: BorderSide(color: designVariables.borderBar)),
+        boxShadow: ComposeBoxTheme.of(context).boxShadow,
+      ),
       // TODO(#720) try a Stack for the overlaid linear progress indicator
       child: Material(
         color: designVariables.composeBoxBg,
@@ -1151,7 +1251,7 @@ class _StreamComposeBoxBody extends _ComposeBoxBody {
   @override Widget buildSendButton() => _SendButton(
     controller: controller,
     getDestination: () => StreamDestination(
-      narrow.streamId, controller.topic.textNormalized),
+      narrow.streamId, TopicName(controller.topic.textNormalized)),
   );
 }
 
@@ -1189,7 +1289,10 @@ sealed class ComposeBoxController {
 }
 
 class StreamComposeBoxController extends ComposeBoxController {
-  final topic = ComposeTopicController();
+  StreamComposeBoxController({required PerAccountStore store})
+    : topic = ComposeTopicController(store: store);
+
+  final ComposeTopicController topic;
   final topicFocusNode = FocusNode();
 
   @override
@@ -1237,6 +1340,10 @@ class _ErrorBanner extends StatelessWidget {
   }
 }
 
+/// The compose box.
+///
+/// Takes the full screen width, covering the horizontal insets with its surface.
+/// Also covers the bottom inset with its surface.
 class ComposeBox extends StatefulWidget {
   ComposeBox({super.key, required this.narrow})
     : assert(ComposeBox.hasComposeBox(narrow));
@@ -1266,16 +1373,20 @@ abstract class ComposeBoxState extends State<ComposeBox> {
   ComposeBoxController get controller;
 }
 
-class _ComposeBoxState extends State<ComposeBox> implements ComposeBoxState {
-  @override ComposeBoxController get controller => _controller;
-  late final ComposeBoxController _controller;
+class _ComposeBoxState extends State<ComposeBox> with PerAccountStoreAwareStateMixin<ComposeBox> implements ComposeBoxState {
+  @override ComposeBoxController get controller => _controller!;
+  ComposeBoxController? _controller;
 
   @override
-  void initState() {
-    super.initState();
+  void onNewStore() {
     switch (widget.narrow) {
       case ChannelNarrow():
-        _controller = StreamComposeBoxController();
+        final store = PerAccountStoreWidget.of(context);
+        if (_controller == null) {
+          _controller = StreamComposeBoxController(store: store);
+        } else {
+          (controller as StreamComposeBoxController).topic.store = store;
+        }
       case TopicNarrow():
       case DmNarrow():
         _controller = FixedDestinationComposeBoxController();
@@ -1288,7 +1399,7 @@ class _ComposeBoxState extends State<ComposeBox> implements ComposeBoxState {
 
   @override
   void dispose() {
-    _controller.dispose();
+    controller.dispose();
     super.dispose();
   }
 
@@ -1328,15 +1439,16 @@ class _ComposeBoxState extends State<ComposeBox> implements ComposeBoxState {
       return _ComposeBoxContainer(body: null, errorBanner: errorBanner);
     }
 
+    final controller = this.controller;
     final narrow = widget.narrow;
-    switch (_controller) {
+    switch (controller) {
       case StreamComposeBoxController(): {
         narrow as ChannelNarrow;
-        body = _StreamComposeBoxBody(controller: _controller, narrow: narrow);
+        body = _StreamComposeBoxBody(controller: controller, narrow: narrow);
       }
       case FixedDestinationComposeBoxController(): {
         narrow as SendableNarrow;
-        body = _FixedDestinationComposeBoxBody(controller: _controller, narrow: narrow);
+        body = _FixedDestinationComposeBoxBody(controller: controller, narrow: narrow);
       }
     }
 
diff --git a/lib/widgets/content.dart b/lib/widgets/content.dart
index f3b369e876..8799e8d192 100644
--- a/lib/widgets/content.dart
+++ b/lib/widgets/content.dart
@@ -1214,7 +1214,7 @@ class GlobalTime extends StatelessWidget {
   final GlobalTimeNode node;
   final TextStyle ambientTextStyle;
 
-  static final _dateFormat = DateFormat('EEE, MMM d, y, h:mm a'); // TODO(intl): localize date
+  static final _dateFormat = DateFormat('EEE, MMM d, y, h:mm a'); // TODO(i18n): localize date
 
   @override
   Widget build(BuildContext context) {
@@ -1319,10 +1319,11 @@ class MessageTableCell extends StatelessWidget {
 
 void _launchUrl(BuildContext context, String urlString) async {
   DialogStatus showError(BuildContext context, String? message) {
+    final zulipLocalizations = ZulipLocalizations.of(context);
     return showErrorDialog(context: context,
-      title: 'Unable to open link',
+      title: zulipLocalizations.errorCouldNotOpenLinkTitle,
       message: [
-        'Link could not be opened: $urlString',
+        zulipLocalizations.errorCouldNotOpenLink(urlString),
         if (message != null) message,
       ].join("\n\n"));
   }
@@ -1570,6 +1571,7 @@ InlineSpan _errorUnimplemented(UnimplementedNode node, {required BuildContext co
   // because release mode isn't yet about general users but developer demos,
   // and we want to keep the demos honest.
   // TODO(#194) think through UX for general release
+  // TODO(#1285) translate this
   final htmlNode = node.htmlNode;
   if (htmlNode is dom.Element) {
     return TextSpan(children: [
diff --git a/lib/widgets/emoji_reaction.dart b/lib/widgets/emoji_reaction.dart
index 98147a54d7..de3e2baa26 100644
--- a/lib/widgets/emoji_reaction.dart
+++ b/lib/widgets/emoji_reaction.dart
@@ -16,38 +16,36 @@ import 'theme.dart';
 
 /// Emoji-reaction styles that differ between light and dark themes.
 class EmojiReactionTheme extends ThemeExtension<EmojiReactionTheme> {
-  EmojiReactionTheme.light() :
-    this._(
-      bgSelected: Colors.white,
-
-      // TODO shadow effect, following web, which uses `box-shadow: inset`:
-      //   https://developer.mozilla.org/en-US/docs/Web/CSS/box-shadow#inset
-      //   Needs Flutter support for something like that:
-      //     https://github.com/flutter/flutter/issues/18636
-      //     https://github.com/flutter/flutter/issues/52999
-      //   Until then use a solid color; a much-lightened version of the shadow color.
-      //   Also adapt by making [borderUnselected] more transparent, so we'll
-      //   want to check that against web when implementing the shadow.
-      bgUnselected: const HSLColor.fromAHSL(0.08, 210, 0.50, 0.875).toColor(),
-
-      borderSelected: Colors.black.withValues(alpha: 0.45),
-
-      // TODO see TODO on [bgUnselected] about shadow effect
-      borderUnselected: Colors.black.withValues(alpha: 0.05),
-
-      textSelected: const HSLColor.fromAHSL(1, 210, 0.20, 0.20).toColor(),
-      textUnselected: const HSLColor.fromAHSL(1, 210, 0.20, 0.25).toColor(),
-    );
-
-  EmojiReactionTheme.dark() :
-    this._(
-      bgSelected: Colors.black.withValues(alpha: 0.8),
-      bgUnselected: Colors.black.withValues(alpha: 0.3),
-      borderSelected: Colors.white.withValues(alpha: 0.75),
-      borderUnselected: Colors.white.withValues(alpha: 0.15),
-      textSelected: Colors.white.withValues(alpha: 0.85),
-      textUnselected: Colors.white.withValues(alpha: 0.75),
-    );
+  static final light = EmojiReactionTheme._(
+    bgSelected: Colors.white,
+
+    // TODO shadow effect, following web, which uses `box-shadow: inset`:
+    //   https://developer.mozilla.org/en-US/docs/Web/CSS/box-shadow#inset
+    //   Needs Flutter support for something like that:
+    //     https://github.com/flutter/flutter/issues/18636
+    //     https://github.com/flutter/flutter/issues/52999
+    //   Until then use a solid color; a much-lightened version of the shadow color.
+    //   Also adapt by making [borderUnselected] more transparent, so we'll
+    //   want to check that against web when implementing the shadow.
+    bgUnselected: const HSLColor.fromAHSL(0.08, 210, 0.50, 0.875).toColor(),
+
+    borderSelected: Colors.black.withValues(alpha: 0.45),
+
+    // TODO see TODO on [bgUnselected] about shadow effect
+    borderUnselected: Colors.black.withValues(alpha: 0.05),
+
+    textSelected: const HSLColor.fromAHSL(1, 210, 0.20, 0.20).toColor(),
+    textUnselected: const HSLColor.fromAHSL(1, 210, 0.20, 0.25).toColor(),
+  );
+
+  static final dark = EmojiReactionTheme._(
+    bgSelected: Colors.black.withValues(alpha: 0.8),
+    bgUnselected: Colors.black.withValues(alpha: 0.3),
+    borderSelected: Colors.white.withValues(alpha: 0.75),
+    borderUnselected: Colors.white.withValues(alpha: 0.15),
+    textSelected: Colors.white.withValues(alpha: 0.85),
+    textUnselected: Colors.white.withValues(alpha: 0.75),
+  );
 
   EmojiReactionTheme._({
     required this.bgSelected,
@@ -149,6 +147,7 @@ class ReactionChip extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final store = PerAccountStoreWidget.of(context);
+    final zulipLocalizations = ZulipLocalizations.of(context);
 
     final reactionType = reactionWithVotes.reactionType;
     final emojiCode = reactionWithVotes.emojiCode;
@@ -162,8 +161,8 @@ class ReactionChip extends StatelessWidget {
       //   // 'Chris、Greg、Alya、Shu'
       ? userIds.map((id) {
           return id == store.selfUserId
-            ? 'You'
-            : store.users[id]?.fullName ?? '(unknown user)'; // TODO(i18n)
+            ? zulipLocalizations.reactedEmojiSelfUser
+            : store.users[id]?.fullName ?? zulipLocalizations.unknownUserName;
         }).join(', ')
       : userIds.length.toString();
 
diff --git a/lib/widgets/home.dart b/lib/widgets/home.dart
index 6b5a497928..d7b1585022 100644
--- a/lib/widgets/home.dart
+++ b/lib/widgets/home.dart
@@ -31,7 +31,7 @@ enum _HomePageTab {
 class HomePage extends StatefulWidget {
   const HomePage({super.key});
 
-  static Route<void> buildRoute({required int accountId}) {
+  static AccountRoute<void> buildRoute({required int accountId}) {
     return MaterialAccountWidgetRoute(accountId: accountId,
       loadingPlaceholderPage: _LoadingPlaceholderPage(accountId: accountId),
       page: const HomePage());
@@ -151,6 +151,11 @@ const kTryAnotherAccountWaitPeriod = Duration(seconds: 5);
 class _LoadingPlaceholderPage extends StatefulWidget {
   const _LoadingPlaceholderPage({required this.accountId});
 
+  /// The relevant account for this page.
+  ///
+  /// The account is not guaranteed to exist in the global store. This can
+  /// happen briefly when the account is removed from the database for logout,
+  /// but before [PerAccountStoreWidget.routeToRemoveOnLogout] is processed.
   final int accountId;
 
   @override
@@ -180,9 +185,15 @@ class _LoadingPlaceholderPageState extends State<_LoadingPlaceholderPage> {
   @override
   Widget build(BuildContext context) {
     final zulipLocalizations = ZulipLocalizations.of(context);
-    final realmUrl = GlobalStoreWidget.of(context)
-      // TODO(#1219) `!` is incorrect
-      .getAccount(widget.accountId)!.realmUrl;
+    final account = GlobalStoreWidget.of(context).getAccount(widget.accountId);
+
+    if (account == null) {
+      // We should only reach this state very briefly.
+      // See [_LoadingPlaceholderPage.accountId].
+      return Scaffold(
+        appBar: AppBar(),
+        body: const SizedBox.shrink());
+    }
 
     return Scaffold(
       appBar: AppBar(),
@@ -201,7 +212,7 @@ class _LoadingPlaceholderPageState extends State<_LoadingPlaceholderPage> {
                 child: Column(
                   children: [
                     const SizedBox(height: 16),
-                    Text(zulipLocalizations.tryAnotherAccountMessage(realmUrl.toString())),
+                    Text(zulipLocalizations.tryAnotherAccountMessage(account.realmUrl.toString())),
                     const SizedBox(height: 8),
                     ElevatedButton(
                       onPressed: () => Navigator.push(context,
diff --git a/lib/widgets/icons.dart b/lib/widgets/icons.dart
index ba21bec42f..82cb83704b 100644
--- a/lib/widgets/icons.dart
+++ b/lib/widgets/icons.dart
@@ -42,92 +42,101 @@ abstract final class ZulipIcons {
   /// The Zulip custom icon "camera".
   static const IconData camera = IconData(0xf106, fontFamily: "Zulip Icons");
 
+  /// The Zulip custom icon "check".
+  static const IconData check = IconData(0xf107, fontFamily: "Zulip Icons");
+
+  /// The Zulip custom icon "check_remove".
+  static const IconData check_remove = IconData(0xf108, fontFamily: "Zulip Icons");
+
   /// The Zulip custom icon "chevron_right".
-  static const IconData chevron_right = IconData(0xf107, fontFamily: "Zulip Icons");
+  static const IconData chevron_right = IconData(0xf109, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "clock".
-  static const IconData clock = IconData(0xf108, fontFamily: "Zulip Icons");
+  static const IconData clock = IconData(0xf10a, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "contacts".
-  static const IconData contacts = IconData(0xf109, fontFamily: "Zulip Icons");
+  static const IconData contacts = IconData(0xf10b, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "copy".
-  static const IconData copy = IconData(0xf10a, fontFamily: "Zulip Icons");
+  static const IconData copy = IconData(0xf10c, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "follow".
-  static const IconData follow = IconData(0xf10b, fontFamily: "Zulip Icons");
+  static const IconData follow = IconData(0xf10d, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "format_quote".
-  static const IconData format_quote = IconData(0xf10c, fontFamily: "Zulip Icons");
+  static const IconData format_quote = IconData(0xf10e, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "globe".
-  static const IconData globe = IconData(0xf10d, fontFamily: "Zulip Icons");
+  static const IconData globe = IconData(0xf10f, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "group_dm".
-  static const IconData group_dm = IconData(0xf10e, fontFamily: "Zulip Icons");
+  static const IconData group_dm = IconData(0xf110, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "hash_italic".
-  static const IconData hash_italic = IconData(0xf10f, fontFamily: "Zulip Icons");
+  static const IconData hash_italic = IconData(0xf111, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "hash_sign".
-  static const IconData hash_sign = IconData(0xf110, fontFamily: "Zulip Icons");
+  static const IconData hash_sign = IconData(0xf112, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "image".
-  static const IconData image = IconData(0xf111, fontFamily: "Zulip Icons");
+  static const IconData image = IconData(0xf113, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "inbox".
-  static const IconData inbox = IconData(0xf112, fontFamily: "Zulip Icons");
+  static const IconData inbox = IconData(0xf114, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "info".
-  static const IconData info = IconData(0xf113, fontFamily: "Zulip Icons");
+  static const IconData info = IconData(0xf115, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "inherit".
-  static const IconData inherit = IconData(0xf114, fontFamily: "Zulip Icons");
+  static const IconData inherit = IconData(0xf116, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "language".
-  static const IconData language = IconData(0xf115, fontFamily: "Zulip Icons");
+  static const IconData language = IconData(0xf117, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "lock".
-  static const IconData lock = IconData(0xf116, fontFamily: "Zulip Icons");
+  static const IconData lock = IconData(0xf118, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "menu".
-  static const IconData menu = IconData(0xf117, fontFamily: "Zulip Icons");
+  static const IconData menu = IconData(0xf119, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "message_feed".
-  static const IconData message_feed = IconData(0xf118, fontFamily: "Zulip Icons");
+  static const IconData message_feed = IconData(0xf11a, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "mute".
-  static const IconData mute = IconData(0xf119, fontFamily: "Zulip Icons");
+  static const IconData mute = IconData(0xf11b, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "read_receipts".
-  static const IconData read_receipts = IconData(0xf11a, fontFamily: "Zulip Icons");
+  static const IconData read_receipts = IconData(0xf11c, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "send".
-  static const IconData send = IconData(0xf11b, fontFamily: "Zulip Icons");
+  static const IconData send = IconData(0xf11d, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "share".
-  static const IconData share = IconData(0xf11c, fontFamily: "Zulip Icons");
+  static const IconData share = IconData(0xf11e, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "share_ios".
-  static const IconData share_ios = IconData(0xf11d, fontFamily: "Zulip Icons");
+  static const IconData share_ios = IconData(0xf11f, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "smile".
-  static const IconData smile = IconData(0xf11e, fontFamily: "Zulip Icons");
+  static const IconData smile = IconData(0xf120, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "star".
-  static const IconData star = IconData(0xf11f, fontFamily: "Zulip Icons");
+  static const IconData star = IconData(0xf121, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "star_filled".
-  static const IconData star_filled = IconData(0xf120, fontFamily: "Zulip Icons");
+  static const IconData star_filled = IconData(0xf122, fontFamily: "Zulip Icons");
+
+  /// The Zulip custom icon "three_person".
+  static const IconData three_person = IconData(0xf123, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "topic".
-  static const IconData topic = IconData(0xf121, fontFamily: "Zulip Icons");
+  static const IconData topic = IconData(0xf124, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "unmute".
-  static const IconData unmute = IconData(0xf122, fontFamily: "Zulip Icons");
+  static const IconData unmute = IconData(0xf125, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "user".
-  static const IconData user = IconData(0xf123, fontFamily: "Zulip Icons");
+  static const IconData user = IconData(0xf126, fontFamily: "Zulip Icons");
 
   // END GENERATED ICON DATA
 }
diff --git a/lib/widgets/inbox.dart b/lib/widgets/inbox.dart
index 12ec8751a1..799f763f1c 100644
--- a/lib/widgets/inbox.dart
+++ b/lib/widgets/inbox.dart
@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 
 import '../api/model/model.dart';
+import '../generated/l10n/zulip_localizations.dart';
 import '../model/narrow.dart';
 import '../model/recent_dm_conversations.dart';
 import '../model/unreads.dart';
@@ -132,7 +133,7 @@ class _InboxPageState extends State<InboxPageBody> with PerAccountStoreAwareStat
       });
 
     for (final MapEntry(key: streamId, value: topics) in sortedUnreadStreams) {
-      final topicItems = <(String, int, bool, int)>[];
+      final topicItems = <_StreamSectionTopicData>[];
       int countInStream = 0;
       bool streamHasMention = false;
       for (final MapEntry(key: topic, value: messageIds) in topics.entries) {
@@ -140,15 +141,20 @@ class _InboxPageState extends State<InboxPageBody> with PerAccountStoreAwareStat
         final countInTopic = messageIds.length;
         final hasMention = messageIds.any((messageId) => unreadsModel!.mentions.contains(messageId));
         if (hasMention) streamHasMention = true;
-        topicItems.add((topic, countInTopic, hasMention, messageIds.last));
+        topicItems.add(_StreamSectionTopicData(
+          topic: topic,
+          count: countInTopic,
+          hasMention: hasMention,
+          lastUnreadId: messageIds.last,
+        ));
         countInStream += countInTopic;
       }
       if (countInStream == 0) {
         continue;
       }
       topicItems.sort((a, b) {
-        final (_, _, _, aLastUnreadId) = a;
-        final (_, _, _, bLastUnreadId) = b;
+        final aLastUnreadId = a.lastUnreadId;
+        final bLastUnreadId = b.lastUnreadId;
         return bLastUnreadId.compareTo(aLastUnreadId);
       });
       sections.add(_StreamSectionData(streamId, countInStream, streamHasMention, topicItems));
@@ -192,11 +198,25 @@ class _StreamSectionData extends _InboxSectionData {
   final int streamId;
   final int count;
   final bool hasMention;
-  final List<(String, int, bool, int)> items;
+  final List<_StreamSectionTopicData> items;
 
   const _StreamSectionData(this.streamId, this.count, this.hasMention, this.items);
 }
 
+class _StreamSectionTopicData {
+  final TopicName topic;
+  final int count;
+  final bool hasMention;
+  final int lastUnreadId;
+
+  const _StreamSectionTopicData({
+    required this.topic,
+    required this.count,
+    required this.hasMention,
+    required this.lastUnreadId,
+  });
+}
+
 abstract class _HeaderItem extends StatelessWidget {
   final bool collapsed;
   final _InboxPageState pageState;
@@ -218,7 +238,7 @@ abstract class _HeaderItem extends StatelessWidget {
     required this.sectionContext,
   });
 
-  String get title;
+  String title(ZulipLocalizations zulipLocalizations);
   IconData get icon;
   Color collapsedIconColor(BuildContext context);
   Color uncollapsedIconColor(BuildContext context);
@@ -238,6 +258,7 @@ abstract class _HeaderItem extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final zulipLocalizations = ZulipLocalizations.of(context);
     final designVariables = DesignVariables.of(context);
     return Material(
       color: collapsed
@@ -272,7 +293,7 @@ abstract class _HeaderItem extends StatelessWidget {
               ).merge(weightVariableTextStyle(context, wght: 600)),
               maxLines: 1,
               overflow: TextOverflow.ellipsis,
-              title))),
+              title(zulipLocalizations)))),
           const SizedBox(width: 12),
           if (hasMention) const _IconMarker(icon: ZulipIcons.at_sign),
           Padding(padding: const EdgeInsetsDirectional.only(end: 16),
@@ -293,7 +314,8 @@ class _AllDmsHeaderItem extends _HeaderItem {
     required super.sectionContext,
   });
 
-  @override String get title => 'Direct messages'; // TODO(i18n)
+  @override String title(ZulipLocalizations zulipLocalizations) =>
+    zulipLocalizations.recentDmConversationsSectionHeader;
   @override IconData get icon => ZulipIcons.user;
 
   // TODO(design) check if this is the right variable for these
@@ -362,16 +384,20 @@ class _DmItem extends StatelessWidget {
     final store = PerAccountStoreWidget.of(context);
     final selfUser = store.users[store.selfUserId]!;
 
+    final zulipLocalizations = ZulipLocalizations.of(context);
     final designVariables = DesignVariables.of(context);
 
     final title = switch (narrow.otherRecipientIds) { // TODO dedupe with [RecentDmConversationsItem]
       [] => selfUser.fullName,
-      [var otherUserId] => store.users[otherUserId]?.fullName ?? '(unknown user)',
+      [var otherUserId] =>
+        store.users[otherUserId]?.fullName ?? zulipLocalizations.unknownUserName,
 
       // TODO(i18n): List formatting, like you can do in JavaScript:
       //   new Intl.ListFormat('ja').format(['Chris', 'Greg', 'Alya', 'Shu'])
       //   // 'Chris、Greg、Alya、Shu'
-      _ => narrow.otherRecipientIds.map((id) => store.users[id]?.fullName ?? '(unknown user)').join(', '),
+      _ => narrow.otherRecipientIds.map(
+        (id) => store.users[id]?.fullName ?? zulipLocalizations.unknownUserName
+      ).join(', '),
     };
 
     return Material(
@@ -417,7 +443,8 @@ class _StreamHeaderItem extends _HeaderItem {
     required super.sectionContext,
   });
 
-  @override String get title => subscription.name;
+  @override String title(ZulipLocalizations zulipLocalizations) =>
+    subscription.name;
   @override IconData get icon => iconDataForStream(subscription);
   @override Color collapsedIconColor(context) =>
     colorSwatchFor(context, subscription).iconOnPlainBackground;
@@ -466,33 +493,23 @@ class _StreamSection extends StatelessWidget {
       child: Column(children: [
         header,
         if (!collapsed) ...data.items.map((item) {
-          final (topic, count, hasMention, _) = item;
-          return _TopicItem(
-            streamId: data.streamId,
-            topic: topic,
-            count: count,
-            hasMention: hasMention,
-          );
+          return _TopicItem(streamId: data.streamId, data: item);
         }),
       ]));
   }
 }
 
 class _TopicItem extends StatelessWidget {
-  const _TopicItem({
-    required this.streamId,
-    required this.topic,
-    required this.count,
-    required this.hasMention,
-  });
+  const _TopicItem({required this.streamId, required this.data});
 
   final int streamId;
-  final String topic;
-  final int count;
-  final bool hasMention;
+  final _StreamSectionTopicData data;
 
   @override
   Widget build(BuildContext context) {
+    final _StreamSectionTopicData(
+      :topic, :count, :hasMention, :lastUnreadId) = data;
+
     final store = PerAccountStoreWidget.of(context);
     final subscription = store.subscriptions[streamId]!;
 
@@ -509,7 +526,9 @@ class _TopicItem extends StatelessWidget {
             MessageListPage.buildRoute(context: context, narrow: narrow));
         },
         onLongPress: () => showTopicActionSheet(context,
-          channelId: streamId, topic: topic),
+          channelId: streamId,
+          topic: topic,
+          someMessageIdInTopic: lastUnreadId),
         child: ConstrainedBox(constraints: const BoxConstraints(minHeight: 34),
           child: Row(crossAxisAlignment: CrossAxisAlignment.center, children: [
             const SizedBox(width: 63),
@@ -524,7 +543,7 @@ class _TopicItem extends StatelessWidget {
                 ),
                 maxLines: 2,
                 overflow: TextOverflow.ellipsis,
-                topic))),
+                topic.displayName))),
             const SizedBox(width: 12),
             if (hasMention) const _IconMarker(icon: ZulipIcons.at_sign),
             // TODO(design) copies the "@" marker color; is there a better color?
diff --git a/lib/widgets/lightbox.dart b/lib/widgets/lightbox.dart
index 4635e496f4..65d013a4b6 100644
--- a/lib/widgets/lightbox.dart
+++ b/lib/widgets/lightbox.dart
@@ -340,7 +340,7 @@ class VideoDurationLabel extends StatelessWidget {
     final hours = value.inHours.toString().padLeft(2, '0');
     final minutes = value.inMinutes.remainder(60).toString().padLeft(2, '0');
     final seconds = value.inSeconds.remainder(60).toString().padLeft(2, '0');
-    return '${hours == '00' ? '' : '$hours:'}$minutes:$seconds';
+    return '${hours == '00' ? '' : '$hours:'}$minutes:$seconds'; // TODO(i18n)
   }
 
   @override
@@ -385,13 +385,14 @@ class _VideoPositionSliderControlState extends State<_VideoPositionSliderControl
 
   @override
   Widget build(BuildContext context) {
+    final zulipLocalizations = ZulipLocalizations.of(context);
     final currentPosition = _isSliderDragging
       ? _sliderValue
       : widget.controller.value.position;
 
     return Row(children: [
       VideoDurationLabel(currentPosition,
-        semanticsLabel: "Current position"),
+        semanticsLabel: zulipLocalizations.lightboxVideoCurrentPosition),
       Expanded(
         child: Slider(
           value: currentPosition.inMilliseconds.toDouble(),
@@ -421,7 +422,7 @@ class _VideoPositionSliderControlState extends State<_VideoPositionSliderControl
         ),
       ),
       VideoDurationLabel(widget.controller.value.duration,
-        semanticsLabel: "Video duration"),
+        semanticsLabel: zulipLocalizations.lightboxVideoDuration),
     ]);
   }
 }
diff --git a/lib/widgets/login.dart b/lib/widgets/login.dart
index ce1cf09438..195bf75e62 100644
--- a/lib/widgets/login.dart
+++ b/lib/widgets/login.dart
@@ -115,6 +115,20 @@ class AddAccountPage extends StatefulWidget {
     return _LoginSequenceRoute(page: const AddAccountPage());
   }
 
+  /// The hint text to show in the "Zulip server URL" input.
+  ///
+  /// If this contains an example value, it must be one that has been reserved
+  /// so that it cannot point to a real Zulip realm (nor any unknown other site).
+  /// The realm name `your-org` under zulipchat.com is reserved for this reason.
+  /// See discussion:
+  ///   https://chat.zulip.org/#narrow/channel/243-mobile-team/topic/flutter.3A.20login.20URL/near/1570347
+  // TODO(i18n): In principle this should be translated, because it's trying to
+  //   convey to the user the English phrase "your org".  But doing that is
+  //   tricky because of the need to have the example name reserved.
+  //   Realistically that probably means we'll only ever translate this for
+  //   at most a handful of languages, most likely none.
+  static const _serverUrlHint = 'your-org.zulipchat.com';
+
   @override
   State<AddAccountPage> createState() => _AddAccountPageState();
 }
@@ -230,10 +244,10 @@ class _AddAccountPageState extends State<AddAccountPage> {
                   // …but leave out unfocusing the input in case more editing is needed.
                 },
                 decoration: InputDecoration(
-                  labelText: zulipLocalizations.loginServerUrlInputLabel,
+                  labelText: zulipLocalizations.loginServerUrlLabel,
                   errorText: errorText,
                   helperText: kLayoutPinningHelperText,
-                  hintText: 'your-org.zulipchat.com')),
+                  hintText: AddAccountPage._serverUrlHint)),
               const SizedBox(height: 8),
               ElevatedButton(
                 onPressed: !_inProgress && errorText == null
diff --git a/lib/widgets/message_list.dart b/lib/widgets/message_list.dart
index 8c32a12115..25993efa30 100644
--- a/lib/widgets/message_list.dart
+++ b/lib/widgets/message_list.dart
@@ -27,56 +27,54 @@ import 'theme.dart';
 
 /// Message-list styles that differ between light and dark themes.
 class MessageListTheme extends ThemeExtension<MessageListTheme> {
-  MessageListTheme.light() :
-    this._(
-      dateSeparator: Colors.black,
-      dateSeparatorText: const HSLColor.fromAHSL(0.75, 0, 0, 0.15).toColor(),
-      dmRecipientHeaderBg: const HSLColor.fromAHSL(1, 46, 0.35, 0.93).toColor(),
-      messageTimestamp: const HSLColor.fromAHSL(0.8, 0, 0, 0.2).toColor(),
-      recipientHeaderText: const HSLColor.fromAHSL(1, 0, 0, 0.15).toColor(),
-      senderBotIcon: const HSLColor.fromAHSL(1, 180, 0.08, 0.65).toColor(),
-      senderName: const HSLColor.fromAHSL(1, 0, 0, 0.2).toColor(),
-      streamMessageBgDefault: Colors.white,
-      streamRecipientHeaderChevronRight: Colors.black.withValues(alpha: 0.3),
-
-      // From the Figma mockup at:
-      //   https://www.figma.com/file/1JTNtYo9memgW7vV6d0ygq/Zulip-Mobile?node-id=132-9684
-      // See discussion about design at:
-      //   https://chat.zulip.org/#narrow/stream/243-mobile-team/topic/flutter.3A.20unread.20marker/near/1658008
-      // (Web uses a left-to-right gradient from hsl(217deg 64% 59%) to transparent,
-      // in both light and dark theme.)
-      unreadMarker: const HSLColor.fromAHSL(1, 227, 0.78, 0.59).toColor(),
-
-      unreadMarkerGap: Colors.white.withValues(alpha: 0.6),
-
-      // TODO(design) this seems ad-hoc; is there a better color?
-      unsubscribedStreamRecipientHeaderBg: const Color(0xfff5f5f5),
-    );
-
-  MessageListTheme.dark() :
-    this._(
-      dateSeparator: Colors.white,
-      dateSeparatorText: const HSLColor.fromAHSL(0.75, 0, 0, 1).toColor(),
-      dmRecipientHeaderBg: const HSLColor.fromAHSL(1, 46, 0.15, 0.2).toColor(),
-      messageTimestamp: const HSLColor.fromAHSL(0.8, 0, 0, 0.85).toColor(),
-      recipientHeaderText: const HSLColor.fromAHSL(0.8, 0, 0, 1).toColor(),
-      senderBotIcon: const HSLColor.fromAHSL(1, 180, 0.05, 0.5).toColor(),
-      senderName: const HSLColor.fromAHSL(0.85, 0, 0, 1).toColor(),
-      streamMessageBgDefault: const HSLColor.fromAHSL(1, 0, 0, 0.15).toColor(),
-      streamRecipientHeaderChevronRight: Colors.white.withValues(alpha: 0.3),
-
-      // 0.75 opacity from here:
-      //   https://www.figma.com/design/1JTNtYo9memgW7vV6d0ygq/Zulip-Mobile?node-id=807-33998&m=dev
-      // Discussion, some weeks after the discussion linked on the light variant:
-      //   https://github.com/zulip/zulip-flutter/pull/317#issuecomment-1784311663
-      // where Vlad includes screenshots that look like they're from there.
-      unreadMarker: const HSLColor.fromAHSL(0.75, 227, 0.78, 0.59).toColor(),
-
-      unreadMarkerGap: Colors.transparent,
-
-      // TODO(design) this is ad-hoc and untested; is there a better color?
-      unsubscribedStreamRecipientHeaderBg: const Color(0xff0a0a0a),
-    );
+  static final light = MessageListTheme._(
+    dateSeparator: Colors.black,
+    dateSeparatorText: const HSLColor.fromAHSL(0.75, 0, 0, 0.15).toColor(),
+    dmRecipientHeaderBg: const HSLColor.fromAHSL(1, 46, 0.35, 0.93).toColor(),
+    messageTimestamp: const HSLColor.fromAHSL(0.8, 0, 0, 0.2).toColor(),
+    recipientHeaderText: const HSLColor.fromAHSL(1, 0, 0, 0.15).toColor(),
+    senderBotIcon: const HSLColor.fromAHSL(1, 180, 0.08, 0.65).toColor(),
+    senderName: const HSLColor.fromAHSL(1, 0, 0, 0.2).toColor(),
+    streamMessageBgDefault: Colors.white,
+    streamRecipientHeaderChevronRight: Colors.black.withValues(alpha: 0.3),
+
+    // From the Figma mockup at:
+    //   https://www.figma.com/file/1JTNtYo9memgW7vV6d0ygq/Zulip-Mobile?node-id=132-9684
+    // See discussion about design at:
+    //   https://chat.zulip.org/#narrow/stream/243-mobile-team/topic/flutter.3A.20unread.20marker/near/1658008
+    // (Web uses a left-to-right gradient from hsl(217deg 64% 59%) to transparent,
+    // in both light and dark theme.)
+    unreadMarker: const HSLColor.fromAHSL(1, 227, 0.78, 0.59).toColor(),
+
+    unreadMarkerGap: Colors.white.withValues(alpha: 0.6),
+
+    // TODO(design) this seems ad-hoc; is there a better color?
+    unsubscribedStreamRecipientHeaderBg: const Color(0xfff5f5f5),
+  );
+
+  static final dark = MessageListTheme._(
+    dateSeparator: Colors.white,
+    dateSeparatorText: const HSLColor.fromAHSL(0.75, 0, 0, 1).toColor(),
+    dmRecipientHeaderBg: const HSLColor.fromAHSL(1, 46, 0.15, 0.2).toColor(),
+    messageTimestamp: const HSLColor.fromAHSL(0.8, 0, 0, 0.85).toColor(),
+    recipientHeaderText: const HSLColor.fromAHSL(0.8, 0, 0, 1).toColor(),
+    senderBotIcon: const HSLColor.fromAHSL(1, 180, 0.05, 0.5).toColor(),
+    senderName: const HSLColor.fromAHSL(0.85, 0, 0, 1).toColor(),
+    streamMessageBgDefault: const HSLColor.fromAHSL(1, 0, 0, 0.15).toColor(),
+    streamRecipientHeaderChevronRight: Colors.white.withValues(alpha: 0.3),
+
+    // 0.75 opacity from here:
+    //   https://www.figma.com/design/1JTNtYo9memgW7vV6d0ygq/Zulip-Mobile?node-id=807-33998&m=dev
+    // Discussion, some weeks after the discussion linked on the light variant:
+    //   https://github.com/zulip/zulip-flutter/pull/317#issuecomment-1784311663
+    // where Vlad includes screenshots that look like they're from there.
+    unreadMarker: const HSLColor.fromAHSL(0.75, 227, 0.78, 0.59).toColor(),
+
+    unreadMarkerGap: Colors.transparent,
+
+    // TODO(design) this is ad-hoc and untested; is there a better color?
+    unsubscribedStreamRecipientHeaderBg: const Color(0xff0a0a0a),
+  );
 
   MessageListTheme._({
     required this.dateSeparator,
@@ -155,7 +153,7 @@ class MessageListTheme extends ThemeExtension<MessageListTheme> {
     return MessageListTheme._(
       dateSeparator: Color.lerp(dateSeparator, other.dateSeparator, t)!,
       dateSeparatorText: Color.lerp(dateSeparatorText, other.dateSeparatorText, t)!,
-      dmRecipientHeaderBg: Color.lerp(streamMessageBgDefault, other.dmRecipientHeaderBg, t)!,
+      dmRecipientHeaderBg: Color.lerp(dmRecipientHeaderBg, other.dmRecipientHeaderBg, t)!,
       messageTimestamp: Color.lerp(messageTimestamp, other.messageTimestamp, t)!,
       recipientHeaderText: Color.lerp(recipientHeaderText, other.recipientHeaderText, t)!,
       senderBotIcon: Color.lerp(senderBotIcon, other.senderBotIcon, t)!,
@@ -177,14 +175,20 @@ abstract class MessageListPageState {
   Narrow get narrow;
 
   /// The controller for this [MessageListPage]'s compose box,
-  /// if this [MessageListPage] offers a compose box.
+  /// if this [MessageListPage] offers a compose box and it has mounted,
+  /// else null.
   ComposeBoxController? get composeBoxController;
+
+  /// The active [MessageListView].
+  ///
+  /// This is null if [MessageList] has not mounted yet.
+  MessageListView? get model;
 }
 
 class MessageListPage extends StatefulWidget {
   const MessageListPage({super.key, required this.initNarrow});
 
-  static Route<void> buildRoute({int? accountId, BuildContext? context,
+  static AccountRoute<void> buildRoute({int? accountId, BuildContext? context,
       required Narrow narrow}) {
     return MaterialAccountWidgetRoute(accountId: accountId, context: context,
       page: MessageListPage(initNarrow: narrow));
@@ -214,9 +218,12 @@ class _MessageListPageState extends State<MessageListPage> implements MessageLis
 
   @override
   ComposeBoxController? get composeBoxController => _composeBoxKey.currentState?.controller;
-
   final GlobalKey<ComposeBoxState> _composeBoxKey = GlobalKey();
 
+  @override
+  MessageListView? get model => _messageListKey.currentState?.model;
+  final GlobalKey<_MessageListState> _messageListKey = GlobalKey();
+
   @override
   void initState() {
     super.initState();
@@ -262,8 +269,6 @@ class _MessageListPageState extends State<MessageListPage> implements MessageLis
 
     List<Widget>? actions;
     if (narrow case TopicNarrow(:final streamId)) {
-      // The helper [_getEffectiveCenterTitle] relies on the fact that we
-      // have at most one action here.
       (actions ??= []).add(IconButton(
         icon: const Icon(ZulipIcons.message_feed),
         tooltip: zulipLocalizations.channelFeedButtonTooltip,
@@ -272,9 +277,12 @@ class _MessageListPageState extends State<MessageListPage> implements MessageLis
             narrow: ChannelNarrow(streamId)))));
     }
 
-    return Scaffold(
+    // Insert a PageRoot here, to provide a context that can be used for
+    // MessageListPage.ancestorOf.
+    return PageRoot(child: Scaffold(
       appBar: ZulipAppBar(
-        title: MessageListAppBarTitle(narrow: narrow),
+        buildTitle: (willCenterTitle) =>
+          MessageListAppBarTitle(narrow: narrow, willCenterTitle: willCenterTitle),
         actions: actions,
         backgroundColor: appBarBackgroundColor,
         shape: removeAppBarBottomBorder
@@ -288,8 +296,11 @@ class _MessageListPageState extends State<MessageListPage> implements MessageLis
       //   we matched to the Figma in 21dbae120. See another frame, which uses that:
       //     https://www.figma.com/file/1JTNtYo9memgW7vV6d0ygq/Zulip-Mobile?node-id=147%3A9088&mode=dev
       body: Builder(
-        builder: (BuildContext context) => Center(
-          child: Column(children: [
+        builder: (BuildContext context) => Column(
+          // Children are expected to take the full horizontal space
+          // and handle the horizontal device insets.
+          // The bottom inset should be handled by the last child only.
+          children: [
             MediaQuery.removePadding(
               // Scaffold knows about the app bar, and so has run this
               // BuildContext, which is under `body`, through
@@ -302,7 +313,11 @@ class _MessageListPageState extends State<MessageListPage> implements MessageLis
               removeBottom: ComposeBox.hasComposeBox(narrow),
 
               child: Expanded(
-                child: MessageList(narrow: narrow, onNarrowChanged: _narrowChanged))),
+                child: MessageList(
+                  key: _messageListKey,
+                  narrow: narrow,
+                  onNarrowChanged: _narrowChanged,
+                ))),
             if (ComposeBox.hasComposeBox(narrow))
               ComposeBox(key: _composeBoxKey, narrow: narrow)
           ]))));
@@ -310,13 +325,19 @@ class _MessageListPageState extends State<MessageListPage> implements MessageLis
 }
 
 class MessageListAppBarTitle extends StatelessWidget {
-  const MessageListAppBarTitle({super.key, required this.narrow});
+  const MessageListAppBarTitle({
+    super.key,
+    required this.narrow,
+    required this.willCenterTitle,
+  });
 
   final Narrow narrow;
+  final bool willCenterTitle;
 
   Widget _buildStreamRow(BuildContext context, {
     ZulipStream? stream,
   }) {
+    final zulipLocalizations = ZulipLocalizations.of(context);
     // A null [Icon.icon] makes a blank space.
     final icon = stream != null ? iconDataForStream(stream) : null;
     return Row(
@@ -328,13 +349,14 @@ class MessageListAppBarTitle extends StatelessWidget {
       children: [
         Icon(size: 16, icon),
         const SizedBox(width: 4),
-        Flexible(child: Text(stream?.name ?? '(unknown channel)')),
+        Flexible(child: Text(
+          stream?.name ?? zulipLocalizations.unknownChannelName)),
       ]);
   }
 
   Widget _buildTopicRow(BuildContext context, {
     required ZulipStream? stream,
-    required String topic,
+    required TopicName topic,
   }) {
     final store = PerAccountStoreWidget.of(context);
     final designVariables = DesignVariables.of(context);
@@ -344,7 +366,7 @@ class MessageListAppBarTitle extends StatelessWidget {
     return Row(
       mainAxisSize: MainAxisSize.min,
       children: [
-        Flexible(child: Text(topic, style: const TextStyle(
+        Flexible(child: Text(topic.displayName, style: const TextStyle(
           fontSize: 13,
         ).merge(weightVariableTextStyle(context)))),
         if (icon != null)
@@ -356,29 +378,6 @@ class MessageListAppBarTitle extends StatelessWidget {
       ]);
   }
 
-  // TODO(upstream): provide an API for this
-  // Adapted from [AppBar._getEffectiveCenterTitle].
-  bool _getEffectiveCenterTitle(ThemeData theme) {
-    bool platformCenter() {
-      switch (theme.platform) {
-        case TargetPlatform.android:
-        case TargetPlatform.fuchsia:
-        case TargetPlatform.linux:
-        case TargetPlatform.windows:
-          return false;
-        case TargetPlatform.iOS:
-        case TargetPlatform.macOS:
-        // We rely on the fact that there is at most one action
-        // on the message list app bar, so that the expression returned
-        // in the original helper, `actions == null || actions!.length < 2`,
-        // always evaluates to `true`:
-          return true;
-      }
-    }
-
-    return theme.appBarTheme.centerTitle ?? platformCenter();
-  }
-
   @override
   Widget build(BuildContext context) {
     final zulipLocalizations = ZulipLocalizations.of(context);
@@ -399,19 +398,29 @@ class MessageListAppBarTitle extends StatelessWidget {
         return _buildStreamRow(context, stream: stream);
 
       case TopicNarrow(:var streamId, :var topic):
-        final theme = Theme.of(context);
         final store = PerAccountStoreWidget.of(context);
         final stream = store.streams[streamId];
-        final centerTitle = _getEffectiveCenterTitle(theme);
         return SizedBox(
           width: double.infinity,
           child: GestureDetector(
             behavior: HitTestBehavior.translucent,
-            onLongPress: () => showTopicActionSheet(context,
-              channelId: streamId, topic: topic),
+            onLongPress: () {
+              final someMessage = MessageListPage.ancestorOf(context)
+                .model?.messages.firstOrNull;
+              // If someMessage is null, the topic action sheet won't have a
+              // resolve/unresolve button. That seems OK; in that case we're
+              // either still fetching messages (and the user can reopen the
+              // sheet after that finishes) or there aren't any messages to
+              // act on anyway.
+              assert(someMessage == null || narrow.containsMessage(someMessage));
+              showTopicActionSheet(context,
+                channelId: streamId,
+                topic: topic,
+                someMessageIdInTopic: someMessage?.id);
+            },
             child: Column(
-              crossAxisAlignment: centerTitle ? CrossAxisAlignment.center
-                                              : CrossAxisAlignment.start,
+              crossAxisAlignment: willCenterTitle ? CrossAxisAlignment.center
+                                                  : CrossAxisAlignment.start,
               children: [
                 _buildStreamRow(context, stream: stream),
                 _buildTopicRow(context, stream: stream, topic: topic),
@@ -420,10 +429,13 @@ class MessageListAppBarTitle extends StatelessWidget {
       case DmNarrow(:var otherRecipientIds):
         final store = PerAccountStoreWidget.of(context);
         if (otherRecipientIds.isEmpty) {
-          return const Text("DMs with yourself");
+          return Text(zulipLocalizations.dmsWithYourselfPageTitle);
         } else {
-          final names = otherRecipientIds.map((id) => store.users[id]?.fullName ?? '(unknown user)');
-          return Text("DMs with ${names.join(", ")}"); // TODO show avatars
+          final names = otherRecipientIds.map(
+            (id) => store.users[id]?.fullName ?? zulipLocalizations.unknownUserName);
+          // TODO show avatars
+          return Text(
+            zulipLocalizations.dmsWithOthersPageTitle(names.join(', ')));
         }
     }
   }
@@ -442,6 +454,12 @@ const _kShortMessageHeight = 80;
 // previous batch.
 const kFetchMessagesBufferPixels = (kMessageListFetchBatchSize / 2) * _kShortMessageHeight;
 
+/// The message list.
+///
+/// Takes the full screen width, keeping its contents
+/// out of the horizontal insets with transparent [SafeArea] padding.
+/// When there is no [ComposeBox], also takes responsibility
+/// for dealing with the bottom inset.
 class MessageList extends StatefulWidget {
   const MessageList({super.key, required this.narrow, required this.onNarrowChanged});
 
@@ -535,12 +553,15 @@ class _MessageListState extends State<MessageList> with PerAccountStoreAwareStat
     // Pad the left and right insets, for small devices in landscape.
     return SafeArea(
       // Don't let this be the place we pad the bottom inset. When there's
-      // no compose box, we want to let the message-list content pad it.
+      // no compose box, we want to let the message-list content
+      // and the scroll-to-bottom button avoid it.
       // TODO(#311) Remove as unnecessary if we do a bottom nav.
       //   The nav will pad the bottom inset, and an ancestor of this widget
       //   will have a `MediaQuery.removePadding` with `removeBottom: true`.
       bottom: false,
 
+      // Horizontally, on wide screens, this Center grows the SafeArea
+      // to position its padding over the device insets and centers content.
       child: Center(
         child: ConstrainedBox(
           constraints: const BoxConstraints(maxWidth: 760),
@@ -553,7 +574,9 @@ class _MessageListState extends State<MessageList> with PerAccountStoreAwareStat
                   bottom: 0,
                   right: 0,
                   // TODO(#311) SafeArea shouldn't be needed if we have a
-                  //   bottom nav. That will pad the bottom inset.
+                  //   bottom nav; that will pad the bottom inset. Remove it,
+                  //   and the mention of bottom-inset handling in
+                  //   MessageList's dartdoc.
                   child: SafeArea(
                     child: ScrollToBottomButton(
                       scrollController: scrollController,
@@ -564,6 +587,7 @@ class _MessageListState extends State<MessageList> with PerAccountStoreAwareStat
   Widget _buildListView(BuildContext context) {
     final length = model!.items.length;
     const centerSliverKey = ValueKey('center sliver');
+    final zulipLocalizations = ZulipLocalizations.of(context);
 
     Widget sliver = SliverStickyHeaderList(
       headerPlacement: HeaderPlacement.scrollingStart,
@@ -600,12 +624,12 @@ class _MessageListState extends State<MessageList> with PerAccountStoreAwareStat
           if (i == 2) return TypingStatusWidget(narrow: widget.narrow);
 
           final data = model!.items[length - 1 - (i - 3)];
-          return _buildItem(data, i);
+          return _buildItem(zulipLocalizations, data, i);
         }));
 
     if (!ComposeBox.hasComposeBox(widget.narrow)) {
-      // TODO(#311) If we have a bottom nav, it will pad the bottom
-      //   inset, and this shouldn't be necessary
+      // TODO(#311) If we have a bottom nav, it will pad the bottom inset,
+      //   and this can be removed; also remove mention in MessageList dartdoc
       sliver = SliverSafeArea(sliver: sliver);
     }
 
@@ -636,13 +660,13 @@ class _MessageListState extends State<MessageList> with PerAccountStoreAwareStat
       ]);
   }
 
-  Widget _buildItem(MessageListItem data, int i) {
+  Widget _buildItem(ZulipLocalizations zulipLocalizations, MessageListItem data, int i) {
     switch (data) {
       case MessageListHistoryStartItem():
-        return const Center(
+        return Center(
           child: Padding(
-            padding: EdgeInsets.symmetric(vertical: 16.0),
-            child: Text("No earlier messages."))); // TODO use an icon
+            padding: const EdgeInsets.symmetric(vertical: 16.0),
+            child: Text(zulipLocalizations.noEarlierMessages))); // TODO use an icon
       case MessageListLoadingItem():
         return const Center(
           child: Padding(
@@ -686,6 +710,7 @@ class ScrollToBottomButton extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final zulipLocalizations = ZulipLocalizations.of(context);
     return ValueListenableBuilder<bool>(
       valueListenable: visibleValue,
       builder: (BuildContext context, bool value, Widget? child) {
@@ -693,7 +718,7 @@ class ScrollToBottomButton extends StatelessWidget {
       },
       // TODO: fix hardcoded values for size and style here
       child: IconButton(
-        tooltip: "Scroll to bottom",
+        tooltip: zulipLocalizations.scrollToBottomTooltip,
         icon: const Icon(Icons.expand_circle_down_rounded),
         iconSize: 40,
         // Web has the same color in light and dark mode.
@@ -880,27 +905,12 @@ class RecipientHeader extends StatelessWidget {
   final Message message;
   final Narrow narrow;
 
-  static bool _containsDifferentChannels(Narrow narrow) {
-    switch (narrow) {
-      case CombinedFeedNarrow():
-      case MentionsNarrow():
-      case StarredMessagesNarrow():
-        return true;
-
-      case ChannelNarrow():
-      case TopicNarrow():
-      case DmNarrow():
-        return false;
-    }
-  }
-
   @override
   Widget build(BuildContext context) {
     final message = this.message;
     return switch (message) {
-      StreamMessage() => StreamMessageRecipientHeader(message: message,
-        showStream: _containsDifferentChannels(narrow)),
-      DmMessage() => DmRecipientHeader(message: message),
+      StreamMessage() => StreamMessageRecipientHeader(message: message, narrow: narrow),
+      DmMessage() => DmRecipientHeader(message: message, narrow: narrow),
     };
   }
 }
@@ -1014,11 +1024,25 @@ class StreamMessageRecipientHeader extends StatelessWidget {
   const StreamMessageRecipientHeader({
     super.key,
     required this.message,
-    required this.showStream,
+    required this.narrow,
   });
 
   final StreamMessage message;
-  final bool showStream;
+  final Narrow narrow;
+
+  static bool _containsDifferentChannels(Narrow narrow) {
+    switch (narrow) {
+      case CombinedFeedNarrow():
+      case MentionsNarrow():
+      case StarredMessagesNarrow():
+        return true;
+
+      case ChannelNarrow():
+      case TopicNarrow():
+      case DmNarrow():
+        return false;
+    }
+  }
 
   @override
   Widget build(BuildContext context) {
@@ -1027,6 +1051,7 @@ class StreamMessageRecipientHeader extends StatelessWidget {
     //   https://github.com/zulip/zulip-mobile/issues/5511
     final store = PerAccountStoreWidget.of(context);
     final designVariables = DesignVariables.of(context);
+    final zulipLocalizations = ZulipLocalizations.of(context);
 
     final topic = message.topic;
 
@@ -1045,13 +1070,13 @@ class StreamMessageRecipientHeader extends StatelessWidget {
     }
 
     final Widget streamWidget;
-    if (!showStream) {
+    if (!_containsDifferentChannels(narrow)) {
       streamWidget = const SizedBox(width: 16);
     } else {
       final stream = store.streams[message.streamId];
       final streamName = stream?.name
         ?? message.displayRecipient
-        ?? '(unknown channel)'; // TODO(log)
+        ?? zulipLocalizations.unknownChannelName; // TODO(log)
 
       streamWidget = GestureDetector(
         onTap: () => Navigator.push(context,
@@ -1091,7 +1116,7 @@ class StreamMessageRecipientHeader extends StatelessWidget {
       child: Row(
         children: [
           Flexible(
-            child: Text(topic,
+            child: Text(topic.displayName,
               // TODO: Give a way to see the whole topic (maybe a
               //   long-press interaction?)
               overflow: TextOverflow.ellipsis,
@@ -1105,11 +1130,18 @@ class StreamMessageRecipientHeader extends StatelessWidget {
         ]));
 
     return GestureDetector(
-      onTap: () => Navigator.push(context,
-        MessageListPage.buildRoute(context: context,
-          narrow: TopicNarrow.ofMessage(message))),
+      // When already in a topic narrow, disable tap interaction that would just
+      // push a MessageListPage for the same topic narrow.
+      // TODO(#1039) simplify by removing topic-narrow condition if we remove
+      //   recipient headers in topic narrows
+      onTap: narrow is TopicNarrow ? null
+        : () => Navigator.push(context,
+            MessageListPage.buildRoute(context: context,
+              narrow: TopicNarrow.ofMessage(message))),
       onLongPress: () => showTopicActionSheet(context,
-        channelId: message.streamId, topic: topic),
+        channelId: message.streamId,
+        topic: topic,
+        someMessageIdInTopic: message.id),
       child: ColoredBox(
         color: backgroundColor,
         child: Row(
@@ -1126,9 +1158,14 @@ class StreamMessageRecipientHeader extends StatelessWidget {
 }
 
 class DmRecipientHeader extends StatelessWidget {
-  const DmRecipientHeader({super.key, required this.message});
+  const DmRecipientHeader({
+    super.key,
+    required this.message,
+    required this.narrow,
+  });
 
   final DmMessage message;
+  final Narrow narrow;
 
   @override
   Widget build(BuildContext context) {
@@ -1149,9 +1186,14 @@ class DmRecipientHeader extends StatelessWidget {
     final messageListTheme = MessageListTheme.of(context);
 
     return GestureDetector(
-      onTap: () => Navigator.push(context,
-        MessageListPage.buildRoute(context: context,
-          narrow: DmNarrow.ofMessage(message, selfUserId: store.selfUserId))),
+      // When already in a DM narrow, disable tap interaction that would just
+      // push a MessageListPage for the same DM narrow.
+      // TODO(#1244) simplify by removing DM-narrow condition if we remove
+      //   recipient headers in DM narrows
+      onTap: narrow is DmNarrow ? null
+        : () => Navigator.push(context,
+            MessageListPage.buildRoute(context: context,
+              narrow: DmNarrow.ofMessage(message, selfUserId: store.selfUserId))),
       child: ColoredBox(
         color: messageListTheme.dmRecipientHeaderBg,
         child: Padding(
@@ -1384,5 +1426,5 @@ class MessageWithPossibleSender extends StatelessWidget {
   }
 }
 
-// TODO web seems to ignore locale in formatting time, but we could do better
+// TODO(i18n): web seems to ignore locale in formatting time, but we could do better
 final _kMessageTimestampFormat = DateFormat('h:mm aa', 'en_US');
diff --git a/lib/widgets/page.dart b/lib/widgets/page.dart
index bebb37c22c..a2c6fe52a1 100644
--- a/lib/widgets/page.dart
+++ b/lib/widgets/page.dart
@@ -3,6 +3,30 @@ import 'package:flutter/material.dart';
 
 import 'store.dart';
 
+/// An [InheritedWidget] for near the root of a page's widget subtree,
+/// providing its [BuildContext].
+///
+/// Useful when needing a context that persists through the page's lifespan,
+/// e.g. for a show-action-sheet function
+/// whose buttons use a context to close the sheet
+/// or show an error dialog / snackbar asynchronously.
+///
+/// (In this scenario, it would be buggy to use the context of the element
+/// that was long-pressed,
+/// if the element can unmount as part of handling a Zulip event.)
+class PageRoot extends InheritedWidget {
+  const PageRoot({super.key, required super.child});
+
+  @override
+  bool updateShouldNotify(covariant PageRoot oldWidget) => false;
+
+  static BuildContext contextOf(BuildContext context) {
+    final element = context.getElementForInheritedWidgetOfExactType<PageRoot>();
+    assert(element != null, 'No PageRoot ancestor');
+    return element!;
+  }
+}
+
 /// A page route that always builds the same widget.
 ///
 /// This is useful for making the route more transparent for a test to inspect.
@@ -11,6 +35,12 @@ abstract class WidgetRoute<T extends Object?> extends PageRoute<T> {
   Widget get page;
 }
 
+/// A page route that specifies a particular Zulip account to use, by ID.
+abstract class AccountRoute<T extends Object?> extends PageRoute<T> {
+  /// The [Account.id] of the account to use for this page.
+  int get accountId;
+}
+
 /// A [MaterialPageRoute] that always builds the same widget.
 ///
 /// This is useful for making the route more transparent for a test to inspect.
@@ -32,8 +62,10 @@ class MaterialWidgetRoute<T extends Object?> extends MaterialPageRoute<T> implem
 }
 
 /// A mixin for providing a given account's per-account store on a page route.
-mixin AccountPageRouteMixin<T extends Object?> on PageRoute<T> {
+mixin AccountPageRouteMixin<T extends Object?> on PageRoute<T> implements AccountRoute<T> {
+  @override
   int get accountId;
+
   Widget? get loadingPlaceholderPage;
 
   @override
@@ -42,7 +74,10 @@ mixin AccountPageRouteMixin<T extends Object?> on PageRoute<T> {
       accountId: accountId,
       placeholder: loadingPlaceholderPage ?? const LoadingPlaceholderPage(),
       routeToRemoveOnLogout: this,
-      child: super.buildPage(context, animation, secondaryAnimation));
+      // PageRoot goes under PerAccountStoreWidget, so the provided context
+      // can be used for PerAccountStoreWidget.of.
+      child: PageRoot(
+        child: super.buildPage(context, animation, secondaryAnimation)));
   }
 }
 
diff --git a/lib/widgets/poll.dart b/lib/widgets/poll.dart
index 07123fe196..dc340d08b8 100644
--- a/lib/widgets/poll.dart
+++ b/lib/widgets/poll.dart
@@ -126,8 +126,8 @@ class _PollWidgetState extends State<PollWidget> {
                 children: [
                   Text(option.text, style: textStyleBold.copyWith(fontSize: 16)),
                   if (option.voters.isNotEmpty)
-                    // TODO(i18n): Localize parenthesis characters.
-                    Text('($voterNames)', style: textStyleVoterNames),
+                    Text(zulipLocalizations.pollVoterNames(voterNames),
+                      style: textStyleVoterNames),
                 ]))),
         ]);
     }
diff --git a/lib/widgets/profile.dart b/lib/widgets/profile.dart
index 57dd76a0ab..327910f6c0 100644
--- a/lib/widgets/profile.dart
+++ b/lib/widgets/profile.dart
@@ -30,7 +30,7 @@ class ProfilePage extends StatelessWidget {
 
   final int userId;
 
-  static Route<void> buildRoute({int? accountId, BuildContext? context,
+  static AccountRoute<void> buildRoute({int? accountId, BuildContext? context,
       required int userId}) {
     return MaterialAccountWidgetRoute(accountId: accountId, context: context,
       page: ProfilePage(userId: userId));
@@ -121,17 +121,18 @@ class _ProfileErrorPage extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final zulipLocalizations = ZulipLocalizations.of(context);
     return Scaffold(
-      appBar: ZulipAppBar(title: const Text('Error')),
-      body: const SingleChildScrollView(
+      appBar: ZulipAppBar(title: Text(zulipLocalizations.errorDialogTitle)),
+      body: SingleChildScrollView(
         child: Padding(
-          padding: EdgeInsets.symmetric(horizontal: 16, vertical: 32),
+          padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 32),
           child: Row(
             mainAxisAlignment: MainAxisAlignment.center,
             children: [
-              Icon(Icons.error),
-              SizedBox(width: 4),
-              Text('Could not show user profile.'),
+              const Icon(Icons.error),
+              const SizedBox(width: 4),
+              Text(zulipLocalizations.errorCouldNotShowUserProfile),
             ]))));
   }
 }
@@ -199,7 +200,7 @@ class _ProfileDataTable extends StatelessWidget {
         // TODO(server): The value's format is undocumented, but empirically
         //   it's a date in ISO format, like 2000-01-01.
         // That's readable as is, but:
-        // TODO format this date using user's locale.
+        // TODO(i18n) format this date using user's locale.
         return _TextWidget(text: value);
 
       case CustomProfileFieldType.shortText:
@@ -290,8 +291,9 @@ class _UserWidget extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final store = PerAccountStoreWidget.of(context);
+    final zulipLocalizations = ZulipLocalizations.of(context);
     final user = store.users[userId];
-    final fullName = user?.fullName ?? '(unknown user)';
+    final fullName = user?.fullName ?? zulipLocalizations.unknownUserName;
     return InkWell(
       onTap: () => Navigator.push(context,
         ProfilePage.buildRoute(context: context,
diff --git a/lib/widgets/recent_dm_conversations.dart b/lib/widgets/recent_dm_conversations.dart
index c9d3131591..ddc32861a3 100644
--- a/lib/widgets/recent_dm_conversations.dart
+++ b/lib/widgets/recent_dm_conversations.dart
@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 
+import '../generated/l10n/zulip_localizations.dart';
 import '../model/narrow.dart';
 import '../model/recent_dm_conversations.dart';
 import '../model/unreads.dart';
@@ -81,6 +82,7 @@ class RecentDmConversationsItem extends StatelessWidget {
     final store = PerAccountStoreWidget.of(context);
     final selfUser = store.users[store.selfUserId]!;
 
+    final zulipLocalizations = ZulipLocalizations.of(context);
     final designVariables = DesignVariables.of(context);
 
     final String title;
@@ -94,13 +96,15 @@ class RecentDmConversationsItem extends StatelessWidget {
         //   (should we offer a "spam folder" style summary screen of recent
         //   1:1 DM conversations from muted users?)
         final otherUser = store.users[otherUserId];
-        title = otherUser?.fullName ?? '(unknown user)';
+        title = otherUser?.fullName ?? zulipLocalizations.unknownUserName;
         avatar = AvatarImage(userId: otherUserId, size: _avatarSize);
       default:
         // TODO(i18n): List formatting, like you can do in JavaScript:
         //   new Intl.ListFormat('ja').format(['Chris', 'Greg', 'Alya'])
         //   // 'Chris、Greg、Alya'
-        title = narrow.otherRecipientIds.map((id) => store.users[id]?.fullName ?? '(unknown user)').join(', ');
+        title = narrow.otherRecipientIds.map(
+          (id) => store.users[id]?.fullName ?? zulipLocalizations.unknownUserName
+        ).join(', ');
         avatar = ColoredBox(color: designVariables.groupDmConversationIconBg,
           child: Center(
             child: Icon(color: designVariables.groupDmConversationIcon,
diff --git a/lib/widgets/sticky_header.dart b/lib/widgets/sticky_header.dart
index 356a056094..24eeb8d518 100644
--- a/lib/widgets/sticky_header.dart
+++ b/lib/widgets/sticky_header.dart
@@ -489,6 +489,11 @@ class _RenderSliverStickyHeaderList extends RenderSliver with RenderSliverHelper
     if (_header != null) adoptChild(_header!);
   }
 
+  /// This sliver's child sliver, a modified [RenderSliverList].
+  ///
+  /// The child manages the items in the list (deferring to [RenderSliverList]);
+  /// and identifies which list item, if any, should be consulted
+  /// for a sticky header.
   _RenderSliverStickyHeaderListInner? get child => _child;
   _RenderSliverStickyHeaderListInner? _child;
   set child(_RenderSliverStickyHeaderListInner? value) {
@@ -552,44 +557,74 @@ class _RenderSliverStickyHeaderList extends RenderSliver with RenderSliverHelper
 
   @override
   void performLayout() {
+    // First, lay out the child sliver.  This does all the normal work of
+    // [RenderSliverList], then calls [_rebuildHeader] on this sliver
+    // so that [header] and [_headerEndBound] are up to date.
     assert(child != null);
     child!.layout(constraints, parentUsesSize: true);
     SliverGeometry geometry = child!.geometry!;
 
+    if (geometry.scrollOffsetCorrection != null) {
+      this.geometry = geometry;
+      return;
+    }
+
+    // We assume [child]'s geometry is free of certain complications.
+    // Probably most or all of these *could* be handled if necessary, just at
+    // the cost of further complicating this code.  Fortunately they aren't,
+    // because [RenderSliverList.performLayout] never has these complications.
+    assert(geometry.paintOrigin == 0);
+    assert(geometry.layoutExtent == geometry.paintExtent);
+    assert(geometry.hitTestExtent == geometry.paintExtent);
+    assert(geometry.visible == (geometry.paintExtent > 0));
+    assert(geometry.maxScrollObstructionExtent == 0);
+    assert(geometry.crossAxisExtent == null);
+    final childExtent = geometry.layoutExtent;
+
     if (header != null) {
       header!.layout(constraints.asBoxConstraints(), parentUsesSize: true);
-
       final headerExtent = header!.size.onAxis(constraints.axis);
+
       final double headerOffset;
       if (_headerEndBound == null) {
-        final paintedHeaderSize = calculatePaintOffset(constraints, from: 0, to: headerExtent);
-        final cacheExtent = calculateCacheOffset(constraints, from: 0, to: headerExtent);
-
-        assert(0 <= paintedHeaderSize && paintedHeaderSize.isFinite);
+        // The header's item has [StickyHeaderItem.allowOverflow] true.
+        // Show the header in full, with one edge at the edge of the viewport,
+        // even if the (visible part of the) item is smaller than the header,
+        // and even if the whole child sliver is smaller than the header.
 
+        final paintedHeaderSize = calculatePaintOffset(constraints, from: 0, to: headerExtent);
         geometry = SliverGeometry( // TODO review interaction with other slivers
           scrollExtent: geometry.scrollExtent,
-          layoutExtent: geometry.layoutExtent,
-          paintExtent: math.max(geometry.paintExtent, paintedHeaderSize),
-          cacheExtent: math.max(geometry.cacheExtent, cacheExtent),
+          layoutExtent: childExtent,
+          paintExtent: math.max(childExtent, paintedHeaderSize),
           maxPaintExtent: math.max(geometry.maxPaintExtent, headerExtent),
-          hitTestExtent: math.max(geometry.hitTestExtent, paintedHeaderSize),
           hasVisualOverflow: geometry.hasVisualOverflow
             || headerExtent > constraints.remainingPaintExtent,
+
+          // The cache extent is an extension of layout, not paint; it controls
+          // where the next sliver should start laying out content.  (See
+          // [SliverConstraints.remainingCacheExtent].)  The header isn't meant
+          // to affect where the next sliver gets laid out, so it shouldn't
+          // affect the cache extent.
+          cacheExtent: geometry.cacheExtent,
         );
 
         headerOffset = _headerAtCoordinateEnd()
-          ? geometry.layoutExtent - headerExtent
+          ? childExtent - headerExtent
           : 0.0;
       } else {
+        // The header's item has [StickyHeaderItem.allowOverflow] false.
+        // Keep the header within the item, pushing the header partly out of
+        // the viewport if the item's visible part is smaller than the header.
+
         // The limiting edge of the header's item,
         // in the outer, non-scrolling coordinates.
         final endBoundAbsolute = axisDirectionIsReversed(constraints.growthAxisDirection)
-          ? geometry.layoutExtent - (_headerEndBound! - constraints.scrollOffset)
+          ? childExtent - (_headerEndBound! - constraints.scrollOffset)
           : _headerEndBound! - constraints.scrollOffset;
 
         headerOffset = _headerAtCoordinateEnd()
-          ? math.max(geometry.layoutExtent - headerExtent, endBoundAbsolute)
+          ? math.max(childExtent - headerExtent, endBoundAbsolute)
           : math.min(0.0, endBoundAbsolute - headerExtent);
       }
 
@@ -706,7 +741,10 @@ class _RenderSliverStickyHeaderListInner extends RenderSliverList {
   ///
   /// This means (child start) < (viewport end) <= (child end).
   RenderBox? _findChildAtEnd() {
-    final endOffset = constraints.scrollOffset + constraints.viewportMainAxisExtent;
+    /// The end of the visible area available to this sliver,
+    /// in this sliver's "scroll offset" coordinates.
+    final endOffset = constraints.scrollOffset
+      + constraints.remainingPaintExtent;
 
     RenderBox? child;
     for (child = lastChild; ; child = childBefore(child)) {
@@ -736,10 +774,23 @@ class _RenderSliverStickyHeaderListInner extends RenderSliverList {
 
     final RenderBox? child;
     switch (widget.headerPlacement._byGrowth(constraints.growthDirection)) {
+      case _HeaderGrowthPlacement.growthStart:
+        if (constraints.remainingPaintExtent < constraints.viewportMainAxisExtent) {
+          // Part of the viewport is occupied already by other slivers.  The way
+          // a RenderViewport does layout means that the already-occupied part is
+          // the part that's before this sliver in the growth direction.
+          // Which means that's the place where the header would go.
+          child = null;
+        } else {
+          child = _findChildAtStart();
+        }
       case _HeaderGrowthPlacement.growthEnd:
+        // The edge this sliver wants to place a header at is the one where
+        // this sliver is free to run all the way to the viewport's edge; any
+        // further slivers in that direction will be laid out after this one.
+        // So if this sliver placed a child there, it's at the edge of the
+        // whole viewport and should determine a header.
         child = _findChildAtEnd();
-      case _HeaderGrowthPlacement.growthStart:
-        child = _findChildAtStart();
     }
 
     (parent! as _RenderSliverStickyHeaderList)._rebuildHeader(child);
diff --git a/lib/widgets/subscription_list.dart b/lib/widgets/subscription_list.dart
index d2faf03b2c..a51e722b51 100644
--- a/lib/widgets/subscription_list.dart
+++ b/lib/widgets/subscription_list.dart
@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 
 import '../api/model/model.dart';
+import '../generated/l10n/zulip_localizations.dart';
 import '../model/narrow.dart';
 import '../model/unreads.dart';
 import 'icons.dart';
@@ -41,10 +42,22 @@ class _SubscriptionListPageBodyState extends State<SubscriptionListPageBody> wit
     });
   }
 
+  static final _startsWithEmojiRegex = RegExp(r'^\p{Emoji}', unicode: true);
+
   void _sortSubs(List<Subscription> list) {
     list.sort((a, b) {
       if (a.isMuted && !b.isMuted) return 1;
       if (!a.isMuted && b.isMuted) return -1;
+
+      // A user gave feedback wanting zulip-flutter to match web in putting
+      // emoji-prefixed channels first; see #1202.
+      // For matching web's ordering completely, see:
+      //   https://github.com/zulip/zulip-flutter/issues/1165
+      final aStartsWithEmoji = _startsWithEmojiRegex.hasMatch(a.name);
+      final bStartsWithEmoji = _startsWithEmojiRegex.hasMatch(b.name);
+      if (aStartsWithEmoji && !bStartsWithEmoji) return -1;
+      if (!aStartsWithEmoji && bStartsWithEmoji) return 1;
+
       // TODO(i18n): add locale-aware sorting
       return a.name.toLowerCase().compareTo(b.name.toLowerCase());
     });
@@ -65,10 +78,8 @@ class _SubscriptionListPageBodyState extends State<SubscriptionListPageBody> wit
 
     // TODO: Implement collapsible topics
 
-    // TODO(i18n): localize strings on page
-    //   Strings here left unlocalized as they likely will not
-    //   exist in the settled design.
     final store = PerAccountStoreWidget.of(context);
+    final zulipLocalizations = ZulipLocalizations.of(context);
 
     final List<Subscription> pinned = [];
     final List<Subscription> unpinned = [];
@@ -90,11 +101,11 @@ class _SubscriptionListPageBodyState extends State<SubscriptionListPageBody> wit
           if (pinned.isEmpty && unpinned.isEmpty)
             const _NoSubscriptionsItem(),
           if (pinned.isNotEmpty) ...[
-            const _SubscriptionListHeader(label: "Pinned"),
+            _SubscriptionListHeader(label: zulipLocalizations.pinnedSubscriptionsLabel),
             _SubscriptionList(unreadsModel: unreadsModel, subscriptions: pinned),
           ],
           if (unpinned.isNotEmpty) ...[
-            const _SubscriptionListHeader(label: "Unpinned"),
+            _SubscriptionListHeader(label: zulipLocalizations.unpinnedSubscriptionsLabel),
             _SubscriptionList(unreadsModel: unreadsModel, subscriptions: unpinned),
           ],
 
@@ -112,11 +123,12 @@ class _NoSubscriptionsItem extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final designVariables = DesignVariables.of(context);
+    final zulipLocalizations = ZulipLocalizations.of(context);
 
     return SliverToBoxAdapter(
       child: Padding(
         padding: const EdgeInsets.all(10),
-        child: Text("No channels found",
+        child: Text(zulipLocalizations.subscriptionListNoChannels,
           textAlign: TextAlign.center,
           style: TextStyle(
             color: designVariables.subscriptionListHeaderText,
diff --git a/lib/widgets/theme.dart b/lib/widgets/theme.dart
index 0ce1d4cdb4..ec8ad8aecc 100644
--- a/lib/widgets/theme.dart
+++ b/lib/widgets/theme.dart
@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 
 import '../api/model/model.dart';
+import 'compose_box.dart';
 import 'content.dart';
 import 'emoji_reaction.dart';
 import 'message_list.dart';
@@ -30,8 +31,9 @@ ThemeData zulipThemeData(BuildContext context) {
       themeExtensions = [
         ContentTheme.light(context),
         designVariables,
-        EmojiReactionTheme.light(),
-        MessageListTheme.light(),
+        EmojiReactionTheme.light,
+        MessageListTheme.light,
+        ComposeBoxTheme.light,
       ];
     }
     case Brightness.dark: {
@@ -39,8 +41,9 @@ ThemeData zulipThemeData(BuildContext context) {
       themeExtensions = [
         ContentTheme.dark(context),
         designVariables,
-        EmojiReactionTheme.dark(),
-        MessageListTheme.dark(),
+        EmojiReactionTheme.dark,
+        MessageListTheme.dark,
+        ComposeBoxTheme.dark,
       ];
     }
   }
@@ -175,7 +178,7 @@ class DesignVariables extends ThemeExtension<DesignVariables> {
     bgMenuButtonActive: Colors.black.withValues(alpha: 0.2),
     bgMenuButtonSelected: Colors.black.withValues(alpha: 0.25),
     bgTopBar: const Color(0xff242424),
-    borderBar: Colors.black.withValues(alpha: 0.5),
+    borderBar: const Color(0xffffffff).withValues(alpha: 0.1),
     borderMenuButtonSelected: Colors.white.withValues(alpha: 0.1),
     btnLabelAttLowIntDanger: const Color(0xffff8b7c),
     btnLabelAttMediumIntDanger: const Color(0xffff8b7c),
diff --git a/macos/Podfile.lock b/macos/Podfile.lock
index 8c7b011db1..7125e9452b 100644
--- a/macos/Podfile.lock
+++ b/macos/Podfile.lock
@@ -3,32 +3,32 @@ PODS:
     - FlutterMacOS
   - file_selector_macos (0.0.1):
     - FlutterMacOS
-  - Firebase/CoreOnly (11.4.2):
-    - FirebaseCore (= 11.4.2)
-  - Firebase/Messaging (11.4.2):
+  - Firebase/CoreOnly (11.6.0):
+    - FirebaseCore (~> 11.6.0)
+  - Firebase/Messaging (11.6.0):
     - Firebase/CoreOnly
-    - FirebaseMessaging (~> 11.4.0)
-  - firebase_core (3.9.0):
-    - Firebase/CoreOnly (~> 11.4.0)
+    - FirebaseMessaging (~> 11.6.0)
+  - firebase_core (3.10.0):
+    - Firebase/CoreOnly (~> 11.6.0)
     - FlutterMacOS
-  - firebase_messaging (15.1.6):
-    - Firebase/CoreOnly (~> 11.4.0)
-    - Firebase/Messaging (~> 11.4.0)
+  - firebase_messaging (15.2.0):
+    - Firebase/CoreOnly (~> 11.6.0)
+    - Firebase/Messaging (~> 11.6.0)
     - firebase_core
     - FlutterMacOS
-  - FirebaseCore (11.4.2):
-    - FirebaseCoreInternal (< 12.0, >= 11.4.2)
+  - FirebaseCore (11.6.0):
+    - FirebaseCoreInternal (~> 11.6.0)
     - GoogleUtilities/Environment (~> 8.0)
     - GoogleUtilities/Logger (~> 8.0)
   - FirebaseCoreInternal (11.6.0):
     - "GoogleUtilities/NSData+zlib (~> 8.0)"
-  - FirebaseInstallations (11.4.0):
-    - FirebaseCore (~> 11.0)
+  - FirebaseInstallations (11.6.0):
+    - FirebaseCore (~> 11.6.0)
     - GoogleUtilities/Environment (~> 8.0)
     - GoogleUtilities/UserDefaults (~> 8.0)
     - PromisesObjC (~> 2.4)
-  - FirebaseMessaging (11.4.0):
-    - FirebaseCore (~> 11.0)
+  - FirebaseMessaging (11.6.0):
+    - FirebaseCore (~> 11.6.0)
     - FirebaseInstallations (~> 11.0)
     - GoogleDataTransport (~> 10.0)
     - GoogleUtilities/AppDelegateSwizzler (~> 8.0)
@@ -158,15 +158,15 @@ EXTERNAL SOURCES:
     :path: Flutter/ephemeral/.symlinks/plugins/wakelock_plus/macos
 
 SPEC CHECKSUMS:
-  device_info_plus: ce1b7762849d3ec103d0e0517299f2db7ad60720
+  device_info_plus: 1b14eed9bf95428983aed283a8d51cce3d8c4215
   file_selector_macos: cc3858c981fe6889f364731200d6232dac1d812d
-  Firebase: 7fd5466678d964be78fbf536d8a3385da19c4828
-  firebase_core: 1dfe1f4d02ad78be0277e320aa3d8384cf46231f
-  firebase_messaging: 61f678060b69a7ae1013e3a939ec8e1c56ef6fcf
-  FirebaseCore: 6b32c57269bd999aab34354c3923d92a6e5f3f84
+  Firebase: 374a441a91ead896215703a674d58cdb3e9d772b
+  firebase_core: 6d9bb8b0ea817e8fe0d928177d42275b45fdba6f
+  firebase_messaging: ae8e88b586e4d50abc7cac5bacf74d21967fd226
+  FirebaseCore: 48b0dd707581cf9c1a1220da68223fb0a562afaa
   FirebaseCoreInternal: d98ab91e2d80a56d7b246856a8885443b302c0c2
-  FirebaseInstallations: 6ef4a1c7eb2a61ee1f74727d7f6ce2e72acf1414
-  FirebaseMessaging: f8a160d99c2c2e5babbbcc90c4a3e15db036aee2
+  FirebaseInstallations: efc0946fc756e4d22d8113f7c761948120322e8c
+  FirebaseMessaging: e1aca1fcc23e8b9eddb0e33f375ff90944623021
   FlutterMacOS: 8f6f14fa908a6fb3fba0cd85dbd81ec4b251fb24
   GoogleDataTransport: aae35b7ea0c09004c3797d53c8c41f66f219d6a7
   GoogleUtilities: 26a3abef001b6533cf678d3eb38fd3f614b7872d
diff --git a/pigeon/notifications.dart b/pigeon/notifications.dart
index 3976899279..708ae4efb5 100644
--- a/pigeon/notifications.dart
+++ b/pigeon/notifications.dart
@@ -129,9 +129,7 @@ class MessagingStyle {
 
   final Person user;
   final String? conversationTitle;
-  // TODO(pigeon): Make list item non-nullable, once pigeon supports non-nullable type arguments.
-  //   https://github.com/flutter/flutter/issues/97848
-  final List<MessagingStyleMessage?> messages;
+  final List<MessagingStyleMessage> messages;
   final bool isGroupConversation;
 }
 
@@ -142,7 +140,7 @@ class Notification {
   Notification({required this.group, required this.extras});
 
   final String group;
-  final Map<String?, String?> extras;
+  final Map<String, String> extras;
   // Various other properties too; add them if needed.
 }
 
@@ -267,7 +265,7 @@ abstract class AndroidNotificationHostApi {
     PendingIntent? contentIntent,
     String? contentText,
     String? contentTitle,
-    Map<String?, String?>? extras,
+    Map<String, String>? extras,
     String? groupKey,
     InboxStyle? inboxStyle,
     bool? isGroupSummary,
diff --git a/pubspec.lock b/pubspec.lock
index e98a6a5339..4ee3317f8d 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -13,10 +13,10 @@ packages:
     dependency: transitive
     description:
       name: _flutterfire_internals
-      sha256: daa1d780fdecf8af925680c06c86563cdd445deea995d5c9176f1302a2b10bbe
+      sha256: "27899c95f9e7ec06c8310e6e0eac967707714b9f1450c4a58fa00ca011a4a8ae"
       url: "https://pub.dev"
     source: hosted
-    version: "1.3.48"
+    version: "1.3.49"
   _macros:
     dependency: transitive
     description: dart
@@ -30,14 +30,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.11.0"
-  analyzer_plugin:
-    dependency: transitive
-    description:
-      name: analyzer_plugin
-      sha256: "9661b30b13a685efaee9f02e5d01ed9f2b423bd889d28a304d02d704aee69161"
-      url: "https://pub.dev"
-    source: hosted
-    version: "0.11.3"
   app_settings:
     dependency: "direct main"
     description:
@@ -138,10 +130,10 @@ packages:
     dependency: transitive
     description:
       name: characters
-      sha256: "04a925763edad70e8443c99234dc3328f442e811f1d8fd1a72f1c8ad0f69a605"
+      sha256: f71061c654a3380576a52b451dd5532377954cf9dbd272a78fc8479606670803
       url: "https://pub.dev"
     source: hosted
-    version: "1.3.0"
+    version: "1.4.0"
   charcode:
     dependency: transitive
     description:
@@ -194,10 +186,10 @@ packages:
     dependency: "direct main"
     description:
       name: collection
-      sha256: a1ace0a119f20aabc852d165077c036cd864315bd99b7eaa10a60100341941bf
+      sha256: "2f5709ae4d3d59dd8f7cd309b4e023046b57d8a6c82130785d2b0e5868084e76"
       url: "https://pub.dev"
     source: hosted
-    version: "1.19.0"
+    version: "1.19.1"
   color_models:
     dependency: "direct overridden"
     description:
@@ -267,10 +259,10 @@ packages:
     dependency: "direct main"
     description:
       name: device_info_plus
-      sha256: a7fd703482b391a87d60b6061d04dfdeab07826b96f9abd8f5ed98068acc0074
+      sha256: "4fa68e53e26ab17b70ca39f072c285562cfc1589df5bb1e9295db90f6645f431"
       url: "https://pub.dev"
     source: hosted
-    version: "10.1.2"
+    version: "11.2.0"
   device_info_plus_platform_interface:
     dependency: transitive
     description:
@@ -283,18 +275,18 @@ packages:
     dependency: "direct main"
     description:
       name: drift
-      sha256: c2d073d35ad441730812f4ea05b5dd031fb81c5f9786a4f5fb77ecd6307b6f74
+      sha256: af3941e4d544727b2eb80590eb64e9cb8d77cd68c7690265502ea6a2427aa621
       url: "https://pub.dev"
     source: hosted
-    version: "2.22.1"
+    version: "2.23.1"
   drift_dev:
     dependency: "direct dev"
     description:
       name: drift_dev
-      sha256: f4ab5d6976b1e31551ceb82ff597a505bda7818ff4f7be08a1da9d55eb6e730c
+      sha256: fa98fdbb7303a1b5b2dc110cb516eda2253a5d291680f8cbc72b1af24099f7f9
       url: "https://pub.dev"
     source: hosted
-    version: "2.22.1"
+    version: "2.23.1"
   fake_async:
     dependency: "direct dev"
     description:
@@ -323,10 +315,10 @@ packages:
     dependency: "direct main"
     description:
       name: file_picker
-      sha256: c2376a6aae82358a9f9ccdd7d1f4006d08faa39a2767cce01031d9f593a8bd3b
+      sha256: c904b4ab56d53385563c7c39d8e9fa9af086f91495dfc48717ad84a42c3cf204
       url: "https://pub.dev"
     source: hosted
-    version: "8.1.6"
+    version: "8.1.7"
   file_selector_linux:
     dependency: transitive
     description:
@@ -363,10 +355,10 @@ packages:
     dependency: "direct main"
     description:
       name: firebase_core
-      sha256: "15d761b95dfa2906dfcc31b7fc6fe293188533d1a3ffe78389ba9e69bd7fdbde"
+      sha256: "0307c1fde82e2b8b97e0be2dab93612aff9a72f31ebe9bfac66ed8b37ef7c568"
       url: "https://pub.dev"
     source: hosted
-    version: "3.9.0"
+    version: "3.10.0"
   firebase_core_platform_interface:
     dependency: transitive
     description:
@@ -387,26 +379,26 @@ packages:
     dependency: "direct main"
     description:
       name: firebase_messaging
-      sha256: "151a3ee68736abf293aab66d1317ade53c88abe1db09c75a0460aebf7767bbdf"
+      sha256: "48a8a59197c1c5174060ba9aa1e0036e9b5a0d28a0cc22d19c1fcabc67fafe3c"
       url: "https://pub.dev"
     source: hosted
-    version: "15.1.6"
+    version: "15.2.0"
   firebase_messaging_platform_interface:
     dependency: transitive
     description:
       name: firebase_messaging_platform_interface
-      sha256: f331ee51e40c243f90cc7bc059222dfec4e5df53125b08d31fb28961b00d2a9d
+      sha256: "9770a8e91f54296829dcaa61ce9b7c2f9ae9abbf99976dd3103a60470d5264dd"
       url: "https://pub.dev"
     source: hosted
-    version: "4.5.49"
+    version: "4.6.0"
   firebase_messaging_web:
     dependency: transitive
     description:
       name: firebase_messaging_web
-      sha256: efaf3fdc54cd77e0eedb8e75f7f01c808828c64d052ddbf94d3009974e47d30f
+      sha256: "329ca4ef45ec616abe6f1d5e58feed0934a50840a65aa327052354ad3c64ed77"
       url: "https://pub.dev"
     source: hosted
-    version: "3.9.5"
+    version: "3.10.0"
   fixnum:
     dependency: transitive
     description:
@@ -446,10 +438,10 @@ packages:
     dependency: "direct dev"
     description:
       name: flutter_lints
-      sha256: "3f41d009ba7172d5ff9be5f6e6e6abb4300e263aab8866d2a0842ed2a70f8f0c"
+      sha256: "5398f14efa795ffb7a33e9b6a08798b26a180edac4ad7db3f231e40f82ce11e1"
       url: "https://pub.dev"
     source: hosted
-    version: "4.0.0"
+    version: "5.0.0"
   flutter_localizations:
     dependency: "direct main"
     description: flutter
@@ -530,10 +522,10 @@ packages:
     dependency: "direct main"
     description:
       name: http_parser
-      sha256: "76d306a1c3afb33fe82e2bbacad62a61f409b5634c915fceb0d799de1a913360"
+      sha256: "178d74305e7866013777bab2c3d8726205dc5a4dd935297175b19a23a2e66571"
       url: "https://pub.dev"
     source: hosted
-    version: "4.1.1"
+    version: "4.1.2"
   image_picker:
     dependency: "direct main"
     description:
@@ -546,10 +538,10 @@ packages:
     dependency: transitive
     description:
       name: image_picker_android
-      sha256: fa8141602fde3f7e2f81dbf043613eb44dfa325fa0bcf93c0f142c9f7a2c193e
+      sha256: b62d34a506e12bb965e824b6db4fbf709ee4589cf5d3e99b45ab2287b008ee0c
       url: "https://pub.dev"
     source: hosted
-    version: "0.8.12+18"
+    version: "0.8.12+20"
   image_picker_for_web:
     dependency: transitive
     description:
@@ -562,10 +554,10 @@ packages:
     dependency: transitive
     description:
       name: image_picker_ios
-      sha256: "4f0568120c6fcc0aaa04511cb9f9f4d29fc3d0139884b1d06be88dcec7641d6b"
+      sha256: "05da758e67bc7839e886b3959848aa6b44ff123ab4b28f67891008afe8ef9100"
       url: "https://pub.dev"
     source: hosted
-    version: "0.8.12+1"
+    version: "0.8.12+2"
   image_picker_linux:
     dependency: transitive
     description:
@@ -586,10 +578,10 @@ packages:
     dependency: transitive
     description:
       name: image_picker_platform_interface
-      sha256: "9ec26d410ff46f483c5519c29c02ef0e02e13a543f882b152d4bfd2f06802f80"
+      sha256: "886d57f0be73c4b140004e78b9f28a8914a09e50c2d816bdd0520051a71236a0"
       url: "https://pub.dev"
     source: hosted
-    version: "2.10.0"
+    version: "2.10.1"
   image_picker_windows:
     dependency: transitive
     description:
@@ -647,10 +639,10 @@ packages:
     dependency: "direct dev"
     description:
       name: json_serializable
-      sha256: c2fcb3920cf2b6ae6845954186420fca40bc0a8abcc84903b7801f17d7050d7c
+      sha256: b0a98230538fe5d0b60a22fb6bf1b6cb03471b53e3324ff6069c591679dd59c9
       url: "https://pub.dev"
     source: hosted
-    version: "6.9.0"
+    version: "6.9.3"
   leak_tracker:
     dependency: transitive
     description:
@@ -687,10 +679,10 @@ packages:
     dependency: transitive
     description:
       name: lints
-      sha256: "976c774dd944a42e83e2467f4cc670daef7eed6295b10b36ae8c85bcbf828235"
+      sha256: c35bb79562d980e9a453fc715854e1ed39e24e7d0297a880ef54e17f9874a9d7
       url: "https://pub.dev"
     source: hosted
-    version: "4.0.0"
+    version: "5.1.1"
   logging:
     dependency: transitive
     description:
@@ -711,10 +703,10 @@ packages:
     dependency: transitive
     description:
       name: matcher
-      sha256: d2323aa2060500f906aa31a895b4030b6da3ebdcc5619d14ce1aada65cd161cb
+      sha256: dc58c723c3c24bf8d3e2d3ad3f2f9d7bd9cf43ec6feaa64181775e60190153f2
       url: "https://pub.dev"
     source: hosted
-    version: "0.12.16+1"
+    version: "0.12.17"
   material_color_utilities:
     dependency: transitive
     description:
@@ -727,18 +719,18 @@ packages:
     dependency: transitive
     description:
       name: meta
-      sha256: bdb68674043280c3428e9ec998512fb681678676b3c54e773629ffe74419f8c7
+      sha256: e3641ec5d63ebf0d9b41bd43201a66e3fc79a65db5f61fc181f04cd27aab950c
       url: "https://pub.dev"
     source: hosted
-    version: "1.15.0"
+    version: "1.16.0"
   mime:
     dependency: "direct main"
     description:
       name: mime
-      sha256: "801fd0b26f14a4a58ccb09d5892c3fbdeff209594300a542492cf13fba9d247a"
+      sha256: "41a20518f0cb1256669420fdba0cd90d21561e560ac240f26ef8322e45bb7ed6"
       url: "https://pub.dev"
     source: hosted
-    version: "1.0.6"
+    version: "2.0.0"
   node_preamble:
     dependency: transitive
     description:
@@ -839,18 +831,18 @@ packages:
     dependency: transitive
     description:
       name: petitparser
-      sha256: c15605cd28af66339f8eb6fbe0e541bfe2d1b72d5825efc6598f3e0a31b9ad27
+      sha256: "07c8f0b1913bcde1ff0d26e57ace2f3012ccbf2b204e070290dad3bb22797646"
       url: "https://pub.dev"
     source: hosted
-    version: "6.0.2"
+    version: "6.1.0"
   pigeon:
     dependency: "direct dev"
     description:
       name: pigeon
-      sha256: ba3727eabe6c23876605d05062de35ab861227ff87a77379898ecd0b8951ef49
+      sha256: "694073e4677d631a5aa2c633c5944140c0e7f361cbf3e55b1709dd11688713bb"
       url: "https://pub.dev"
     source: hosted
-    version: "20.0.2"
+    version: "22.7.2"
   platform:
     dependency: transitive
     description:
@@ -903,10 +895,10 @@ packages:
     dependency: transitive
     description:
       name: pubspec_parse
-      sha256: "81876843eb50dc2e1e5b151792c9a985c5ed2536914115ed04e9c8528f6647b0"
+      sha256: "0560ba233314abbed0a48a2956f7f022cce7c3e1e73df540277da7544cad4082"
       url: "https://pub.dev"
     source: hosted
-    version: "1.4.0"
+    version: "1.5.0"
   recase:
     dependency: transitive
     description:
@@ -972,10 +964,10 @@ packages:
     dependency: transitive
     description:
       name: source_gen
-      sha256: "14658ba5f669685cd3d63701d01b31ea748310f7ab854e471962670abcf57832"
+      sha256: "35c8150ece9e8c8d263337a265153c3329667640850b9304861faea59fc98f6b"
       url: "https://pub.dev"
     source: hosted
-    version: "1.5.0"
+    version: "2.0.0"
   source_helper:
     dependency: transitive
     description:
@@ -1020,10 +1012,10 @@ packages:
     dependency: "direct main"
     description:
       name: sqlite3
-      sha256: cb7f4e9dc1b52b1fa350f7b3d41c662e75fc3d399555fa4e5efcf267e9a4fbb5
+      sha256: c284434c408d207863800341298cadfde23abe074a0f01b19c9d8cce4edb8eaa
       url: "https://pub.dev"
     source: hosted
-    version: "2.5.0"
+    version: "2.6.0"
   sqlite3_flutter_libs:
     dependency: "direct main"
     description:
@@ -1044,18 +1036,18 @@ packages:
     dependency: "direct dev"
     description:
       name: stack_trace
-      sha256: "9f47fd3630d76be3ab26f0ee06d213679aa425996925ff3feffdec504931c377"
+      sha256: "8b27215b45d22309b5cddda1aa2b19bdfec9df0e765f2de506401c071d38d1b1"
       url: "https://pub.dev"
     source: hosted
-    version: "1.12.0"
+    version: "1.12.1"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
-      sha256: ba2aa5d8cc609d96bbb2899c28934f9e1af5cddbd60a827822ea467161eb54e7
+      sha256: "969e04c80b8bcdf826f8f16579c7b14d780458bd97f56d107d3950fdbeef059d"
       url: "https://pub.dev"
     source: hosted
-    version: "2.1.2"
+    version: "2.1.4"
   stream_transform:
     dependency: transitive
     description:
@@ -1068,10 +1060,10 @@ packages:
     dependency: transitive
     description:
       name: string_scanner
-      sha256: "0bd04f5bb74fcd6ff0606a888a30e917af9bd52820b178eaa464beb11dca84b6"
+      sha256: "921cd31725b72fe181906c6a94d987c78e3b98c2e205b397ea399d4054872b43"
       url: "https://pub.dev"
     source: hosted
-    version: "1.4.0"
+    version: "1.4.1"
   sync_http:
     dependency: transitive
     description:
@@ -1084,10 +1076,10 @@ packages:
     dependency: transitive
     description:
       name: term_glyph
-      sha256: a29248a84fbb7c79282b40b8c72a1209db169a2e0542bce341da992fe1bc7e84
+      sha256: "7f554798625ea768a7518313e58f83891c7f5024f88e46e7182a4558850a4b8e"
       url: "https://pub.dev"
     source: hosted
-    version: "1.2.1"
+    version: "1.2.2"
   test:
     dependency: "direct dev"
     description:
@@ -1180,18 +1172,18 @@ packages:
     dependency: transitive
     description:
       name: url_launcher_web
-      sha256: "772638d3b34c779ede05ba3d38af34657a05ac55b06279ea6edd409e323dca8e"
+      sha256: "3ba963161bd0fe395917ba881d320b9c4f6dd3c4a233da62ab18a5025c85f1e9"
       url: "https://pub.dev"
     source: hosted
-    version: "2.3.3"
+    version: "2.4.0"
   url_launcher_windows:
     dependency: transitive
     description:
       name: url_launcher_windows
-      sha256: "44cf3aabcedde30f2dba119a9dea3b0f2672fbe6fa96e85536251d678216b3c4"
+      sha256: "3284b6d2ac454cf34f114e1d3319866fdd1e19cdc329999057e44ffe936cfa77"
       url: "https://pub.dev"
     source: hosted
-    version: "3.1.3"
+    version: "3.1.4"
   uuid:
     dependency: transitive
     description:
@@ -1220,18 +1212,18 @@ packages:
     dependency: transitive
     description:
       name: video_player_android
-      sha256: "391e092ba4abe2f93b3e625bd6b6a6ec7d7414279462c1c0ee42b5ab8d0a0898"
+      sha256: "7018dbcb395e2bca0b9a898e73989e67c0c4a5db269528e1b036ca38bcca0d0b"
       url: "https://pub.dev"
     source: hosted
-    version: "2.7.16"
+    version: "2.7.17"
   video_player_avfoundation:
     dependency: transitive
     description:
       name: video_player_avfoundation
-      sha256: "33224c19775fd244be2d6e3dbd8e1826ab162877bd61123bf71890772119a2b7"
+      sha256: "61c54fb08fee52861d819a9b3b8e30b92456dad43a875434c677c892eb7772de"
       url: "https://pub.dev"
     source: hosted
-    version: "2.6.5"
+    version: "2.6.6"
   video_player_platform_interface:
     dependency: "direct dev"
     description:
@@ -1324,10 +1316,10 @@ packages:
     dependency: transitive
     description:
       name: win32
-      sha256: "8b338d4486ab3fbc0ba0db9f9b4f5239b6697fcee427939a40e720cbb9ee0a69"
+      sha256: "154360849a56b7b67331c21f09a386562d88903f90a1099c5987afc1912e1f29"
       url: "https://pub.dev"
     source: hosted
-    version: "5.9.0"
+    version: "5.10.0"
   win32_registry:
     dependency: transitive
     description:
@@ -1368,5 +1360,5 @@ packages:
     source: path
     version: "0.0.1"
 sdks:
-  dart: ">=3.7.0-267.0.dev <4.0.0"
-  flutter: ">=3.28.0-2.0.pre.38575"
+  dart: ">=3.8.0-24.0.dev <4.0.0"
+  flutter: ">=3.29.0-1.0.pre.105"
diff --git a/pubspec.yaml b/pubspec.yaml
index c81b52a367..cc1d93cca8 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -8,14 +8,14 @@ description: A Zulip client for Android and iOS
 publish_to: 'none'
 
 # Keep the last two numbers equal; see docs/release.md.
-version: 0.0.24+24
+version: 0.0.26+26
 
 environment:
   # We use a recent version of Flutter from its main channel, and
   # the corresponding recent version of the Dart SDK.
   # Feel free to update these regularly; see README.md for instructions.
-  sdk: '>=3.7.0-267.0.dev <4.0.0'
-  flutter: '>=3.28.0-2.0.pre.38575'  # 65ff060283e19423e9538c18c24e44495b70aeff
+  sdk: '>=3.8.0-24.0.dev <4.0.0'
+  flutter: '>=3.29.0-1.0.pre.105'  # c1ffaa9d9deb3e0853176271922e0b1c1356d21f
 
 # To update dependencies, see instructions in README.md.
 dependencies:
@@ -39,7 +39,7 @@ dependencies:
   collection: ^1.17.2
   convert: ^3.1.1
   crypto: ^3.0.3
-  device_info_plus: ^10.0.1
+  device_info_plus: ^11.2.0
   drift: ^2.5.0
   file_picker: ^8.0.0+1
   firebase_core: ^3.3.0
@@ -50,7 +50,7 @@ dependencies:
   http_parser: ^4.0.2
   image_picker: ^1.0.0
   json_annotation: ^4.9.0
-  mime: ^1.0.5
+  mime: ^2.0.0
   package_info_plus: ^8.0.0
   path: ^1.8.3
   path_provider: ^2.0.13
@@ -97,11 +97,11 @@ dev_dependencies:
   drift_dev: ^2.5.2
   fake_async: ^1.3.1
   flutter_checks: ^0.1.1
-  flutter_lints: ^4.0.0
+  flutter_lints: ^5.0.0
   ini: ^2.1.0
   json_serializable: ^6.5.4
   legacy_checks: ^0.1.0
-  pigeon: ^20.0.1
+  pigeon: ^22.7.2
   plugin_platform_interface: ^2.1.8
   stack_trace: ^1.11.1
   test: ^1.23.1
diff --git a/test/api/model/events_checks.dart b/test/api/model/events_checks.dart
index f95c6b4362..c1fa0a117f 100644
--- a/test/api/model/events_checks.dart
+++ b/test/api/model/events_checks.dart
@@ -51,8 +51,8 @@ extension UpdateMessageEventChecks on Subject<UpdateMessageEvent> {
   Subject<int?> get origStreamId => has((e) => e.origStreamId, 'origStreamId');
   Subject<int?> get newStreamId => has((e) => e.newStreamId, 'newStreamId');
   Subject<PropagateMode?> get propagateMode => has((e) => e.propagateMode, 'propagateMode');
-  Subject<String?> get origTopic => has((e) => e.origTopic, 'origTopic');
-  Subject<String?> get newTopic => has((e) => e.newTopic, 'newTopic');
+  Subject<TopicName?> get origTopic => has((e) => e.origTopic, 'origTopic');
+  Subject<TopicName?> get newTopic => has((e) => e.newTopic, 'newTopic');
   Subject<String?> get origContent => has((e) => e.origContent, 'origContent');
   Subject<String?> get origRenderedContent => has((e) => e.origRenderedContent, 'origRenderedContent');
   Subject<String?> get content => has((e) => e.content, 'content');
@@ -77,7 +77,7 @@ extension TypingEventChecks on Subject<TypingEvent> {
   Subject<int> get senderId => has((e) => e.senderId, 'senderId');
   Subject<List<int>?> get recipientIds => has((e) => e.recipientIds, 'recipientIds');
   Subject<int?> get streamId => has((e) => e.streamId, 'streamId');
-  Subject<String?> get topic => has((e) => e.topic, 'topic');
+  Subject<TopicName?> get topic => has((e) => e.topic, 'topic');
 }
 
 extension HeartbeatEventChecks on Subject<HeartbeatEvent> {
diff --git a/test/api/model/events_test.dart b/test/api/model/events_test.dart
index 0f1f52f843..51b36350cc 100644
--- a/test/api/model/events_test.dart
+++ b/test/api/model/events_test.dart
@@ -116,8 +116,8 @@ void main() {
         'orig_subject': 'foo',
         'subject': 'bar',
       }) as UpdateMessageEvent)
-        ..origTopic.equals('foo')
-        ..newTopic.equals('bar');
+        ..origTopic.equals(const TopicName('foo'))
+        ..newTopic.equals(const TopicName('bar'));
     });
   });
 
diff --git a/test/api/model/initial_snapshot_test.dart b/test/api/model/initial_snapshot_test.dart
index 7b441de779..3228602fff 100644
--- a/test/api/model/initial_snapshot_test.dart
+++ b/test/api/model/initial_snapshot_test.dart
@@ -1,6 +1,7 @@
 import 'package:checks/checks.dart';
 import 'package:test/scaffolding.dart';
 import 'package:zulip/api/model/initial_snapshot.dart';
+import 'package:zulip/api/model/model.dart';
 
 import '../../stdlib_checks.dart';
 
@@ -20,7 +21,7 @@ void main() {
 
     check(snapshot.channels).single.jsonEquals(
       UnreadChannelSnapshot(
-        topic: 'topic name', streamId: 1,
+        topic: const TopicName('topic name'), streamId: 1,
         unreadMessageIds: [1, 2]));
   });
 
diff --git a/test/api/model/model_checks.dart b/test/api/model/model_checks.dart
index 6a3eee8c8c..8b39b1ad57 100644
--- a/test/api/model/model_checks.dart
+++ b/test/api/model/model_checks.dart
@@ -38,7 +38,6 @@ extension MessageChecks on Subject<Message> {
   Subject<String> get senderFullName => has((e) => e.senderFullName, 'senderFullName');
   Subject<int> get senderId => has((e) => e.senderId, 'senderId');
   Subject<String> get senderRealmStr => has((e) => e.senderRealmStr, 'senderRealmStr');
-  Subject<String> get topic => has((e) => e.topic, 'topic');
   Subject<Poll?> get poll => has((e) => e.poll, 'poll');
   Subject<int> get timestamp => has((e) => e.timestamp, 'timestamp');
   Subject<String> get type => has((e) => e.type, 'type');
@@ -47,8 +46,14 @@ extension MessageChecks on Subject<Message> {
   Subject<String?> get matchTopic => has((e) => e.matchTopic, 'matchTopic');
 }
 
+extension TopicNameChecks on Subject<TopicName> {
+  Subject<String> get apiName => has((x) => x.apiName, 'apiName');
+  Subject<String> get displayName => has((x) => x.displayName, 'displayName');
+}
+
 extension StreamMessageChecks on Subject<StreamMessage> {
   Subject<String?> get displayRecipient => has((e) => e.displayRecipient, 'displayRecipient');
+  Subject<TopicName> get topic => has((e) => e.topic, 'topic');
 }
 
 extension ReactionsChecks on Subject<Reactions> {
diff --git a/test/api/model/model_test.dart b/test/api/model/model_test.dart
index b3636b5ed6..95737c173f 100644
--- a/test/api/model/model_test.dart
+++ b/test/api/model/model_test.dart
@@ -89,7 +89,8 @@ void main() {
       check(baseStreamJson()).not((it) => it.containsKey('topic'));
       check(Message.fromJson(baseStreamJson()
         ..['subject'] = 'hello'
-      )).topic.equals('hello');
+      )).isA<StreamMessage>()
+        .topic.equals(const TopicName('hello'));
     });
 
     test('match_subject -> matchTopic', () {
@@ -125,6 +126,43 @@ void main() {
     // MessageEditState group.
   });
 
+  group('TopicName', () {
+    test('unresolve', () {
+      void doCheck(TopicName input, TopicName expected) {
+        final output = input.unresolve();
+        check(output).apiName.equals(expected.apiName);
+      }
+
+      doCheck(eg.t('some topic'),       eg.t('some topic'));
+      doCheck(eg.t('Some Topic'),       eg.t('Some Topic'));
+      doCheck(eg.t('✔ some topic'),     eg.t('some topic'));
+      doCheck(eg.t('✔ Some Topic'),     eg.t('Some Topic'));
+
+      doCheck(eg.t('Some ✔ Topic'),     eg.t('Some ✔ Topic'));
+      doCheck(eg.t('✔ Some ✔ Topic'),   eg.t('Some ✔ Topic'));
+
+      doCheck(eg.t('✔ ✔✔✔ some topic'), eg.t('some topic'));
+      doCheck(eg.t('✔ ✔ ✔✔some topic'), eg.t('some topic'));
+    });
+
+    test('isSameAs', () {
+      void doCheck(TopicName topicA, TopicName topicB, bool expected) {
+        check(topicA.isSameAs(topicB)).equals(expected);
+      }
+
+      doCheck(eg.t('some topic'),   eg.t('some topic'),   true);
+      doCheck(eg.t('SOME TOPIC'),   eg.t('SOME TOPIC'),   true);
+      doCheck(eg.t('Some Topic'),   eg.t('sOME tOPIC'),   true);
+      doCheck(eg.t('✔ a'),          eg.t('✔ a'),          true);
+
+      doCheck(eg.t('✔ some topic'), eg.t('some topic'),   false);
+      doCheck(eg.t('SOME TOPIC'),   eg.t('✔ SOME TOPIC'), false);
+      doCheck(eg.t('✔ Some Topic'), eg.t('sOME tOPIC'),   false);
+
+      doCheck(eg.t('✔ a'),          eg.t('✔ b'),          false);
+    });
+  });
+
   group('DmMessage', () {
     final Map<String, dynamic> baseJson = Map.unmodifiable(deepToJson(
       eg.dmMessage(from: eg.otherUser, to: [eg.selfUser]),
@@ -287,10 +325,35 @@ void main() {
         ]);
       });
 
+      // Technically the topic *was* unresolved, so MessageEditState.none
+      // would be valid and preferable -- if it didn't need more intense
+      // computation than we're comfortable with in a hot codepath, i.e.,
+      // a regex test instead of a simple `startsWith` / `substring` check.
+      // See comment on the implementation, and discussion:
+      //   https://github.com/zulip/zulip-flutter/pull/1242#discussion_r1917592157
       test('Unresolving topic with a weird prefix -> moved', () {
           checkEditState(MessageEditState.moved,
             [{'prev_topic': '✔ ✔old_topic', 'topic': 'old_topic'}]);
       });
+
+      // Similar reasoning as in the previous test.
+      // Also, Zulip doesn't produce topics with a weird resolved-topic prefix,
+      // so this case can only be produced by unusual input in an
+      // edit/move-topic UI. A "moved" marker seems like a fine response
+      // in that circumstance.
+      test('Resolving topic with a weird prefix -> moved', () {
+          checkEditState(MessageEditState.moved,
+            [{'prev_topic': 'old_topic', 'topic': '✔ ✔old_topic'}]);
+      });
+
+      // Similar reasoning as the previous test, including that this case had to
+      // involve unusual input in an edit/move-topic UI.
+      // Here the computation burden would have come from calling
+      // [TopicName.canonicalize].
+      test('Topic was resolved but with changed case -> moved', () {
+        checkEditState(MessageEditState.moved,
+          [{'prev_topic': 'old ToPiC', 'topic': '✔ OLD tOpIc'}]);
+      });
     });
   });
 }
diff --git a/test/api/notifications_test.dart b/test/api/notifications_test.dart
index fd4465f33a..53240d7b09 100644
--- a/test/api/notifications_test.dart
+++ b/test/api/notifications_test.dart
@@ -1,5 +1,6 @@
 import 'package:checks/checks.dart';
 import 'package:test/scaffolding.dart';
+import 'package:zulip/api/model/model.dart';
 import 'package:zulip/api/notifications.dart';
 
 import '../stdlib_checks.dart';
@@ -81,7 +82,7 @@ void main() {
         ..recipient.isA<FcmMessageChannelRecipient>().which((it) => it
           ..streamId.equals(42)
           ..streamName.equals(streamJson['stream']!)
-          ..topic.equals(streamJson['topic']!))
+          ..topic.jsonEquals(streamJson['topic']!))
         ..content.equals(streamJson['content']!)
         ..time.equals(1546300800);
 
@@ -279,7 +280,7 @@ extension MessageFcmMessageChecks on Subject<MessageFcmMessage> {
 extension FcmMessageChannelRecipientChecks on Subject<FcmMessageChannelRecipient> {
   Subject<int> get streamId => has((x) => x.streamId, 'streamId');
   Subject<String?> get streamName => has((x) => x.streamName, 'streamName');
-  Subject<String> get topic => has((x) => x.topic, 'topic');
+  Subject<TopicName> get topic => has((x) => x.topic, 'topic');
 }
 
 extension FcmMessageDmRecipientChecks on Subject<FcmMessageDmRecipient> {
diff --git a/test/api/route/channels_test.dart b/test/api/route/channels_test.dart
index d86c9447fe..011dc508c5 100644
--- a/test/api/route/channels_test.dart
+++ b/test/api/route/channels_test.dart
@@ -12,7 +12,7 @@ void main() {
     return FakeApiConnection.with_((connection) async {
       connection.prepare(json: {});
       await updateUserTopic(connection,
-        streamId: 1, topic: 'topic',
+        streamId: 1, topic: const TopicName('topic'),
         visibilityPolicy: UserTopicVisibilityPolicy.followed);
       check(connection.takeRequests()).single.isA<http.Request>()
         ..method.equals('POST')
@@ -28,7 +28,7 @@ void main() {
   test('updateUserTopic only accepts valid visibility policy', () {
     return FakeApiConnection.with_((connection) async {
       check(() => updateUserTopic(connection,
-        streamId: 1, topic: 'topic',
+        streamId: 1, topic: const TopicName('topic'),
         visibilityPolicy: UserTopicVisibilityPolicy.unknown),
       ).throws<AssertionError>();
     });
@@ -38,7 +38,7 @@ void main() {
     return FakeApiConnection.with_((connection) async {
       connection.prepare(json: {});
       await updateUserTopicCompat(connection,
-        streamId: 1, topic: 'topic',
+        streamId: 1, topic: const TopicName('topic'),
         visibilityPolicy: UserTopicVisibilityPolicy.followed);
       check(connection.takeRequests()).single.isA<http.Request>()
         ..method.equals('POST')
@@ -55,7 +55,7 @@ void main() {
     test('updateUserTopic throws AssertionError when FL < 170', () {
       return FakeApiConnection.with_(zulipFeatureLevel: 169, (connection) async {
         check(() => updateUserTopic(connection,
-          streamId: 1, topic: 'topic',
+          streamId: 1, topic: const TopicName('topic'),
           visibilityPolicy: UserTopicVisibilityPolicy.muted),
         ).throws<AssertionError>();
       });
@@ -64,7 +64,7 @@ void main() {
     test('updateUserTopicCompat throws UnsupportedError on unsupported policy', () {
       return FakeApiConnection.with_(zulipFeatureLevel: 169, (connection) async {
         check(() => updateUserTopicCompat(connection,
-          streamId: 1, topic: 'topic',
+          streamId: 1, topic: const TopicName('topic'),
           visibilityPolicy: UserTopicVisibilityPolicy.followed),
         ).throws<UnsupportedError>();
       });
@@ -74,7 +74,7 @@ void main() {
       return FakeApiConnection.with_(zulipFeatureLevel: 169, (connection) async {
         connection.prepare(json: {});
         await updateUserTopicCompat(connection,
-          streamId: 1, topic: 'topic',
+          streamId: 1, topic: const TopicName('topic'),
           visibilityPolicy: UserTopicVisibilityPolicy.none);
         check(connection.takeRequests()).single.isA<http.Request>()
           ..method.equals('PATCH')
@@ -91,7 +91,7 @@ void main() {
       return FakeApiConnection.with_(zulipFeatureLevel: 169, (connection) async {
         connection.prepare(json: {});
         await updateUserTopicCompat(connection,
-          streamId: 1, topic: 'topic',
+          streamId: 1, topic: const TopicName('topic'),
           visibilityPolicy: UserTopicVisibilityPolicy.muted);
         check(connection.takeRequests()).single.isA<http.Request>()
           ..method.equals('PATCH')
diff --git a/test/api/route/messages_test.dart b/test/api/route/messages_test.dart
index c634c87ff7..4da4334bae 100644
--- a/test/api/route/messages_test.dart
+++ b/test/api/route/messages_test.dart
@@ -184,7 +184,7 @@ void main() {
       checkNarrow(const ChannelNarrow(12).apiEncode(), jsonEncode([
         {'operator': 'stream', 'operand': 12},
       ]));
-      checkNarrow(const TopicNarrow(12, 'stuff').apiEncode(), jsonEncode([
+      checkNarrow(eg.topicNarrow(12, 'stuff').apiEncode(), jsonEncode([
         {'operator': 'stream', 'operand': 12},
         {'operator': 'topic', 'operand': 'stuff'},
       ]));
@@ -328,7 +328,7 @@ void main() {
     test('smoke', () {
       return FakeApiConnection.with_((connection) async {
         await checkSendMessage(connection,
-          destination: const StreamDestination(streamId, topic), content: content,
+          destination: StreamDestination(streamId, eg.t(topic)), content: content,
           queueId: 'abc:123',
           localId: '456',
           readBySender: true,
@@ -347,7 +347,7 @@ void main() {
     test('to stream', () {
       return FakeApiConnection.with_((connection) async {
         await checkSendMessage(connection,
-          destination: const StreamDestination(streamId, topic), content: content,
+          destination: StreamDestination(streamId, eg.t(topic)), content: content,
           readBySender: true,
           expectedBodyFields: {
             'type': 'stream',
@@ -391,7 +391,7 @@ void main() {
     test('when readBySender is null, sends a User-Agent we know the server will recognize', () {
       return FakeApiConnection.with_((connection) async {
         await checkSendMessage(connection,
-          destination: const StreamDestination(streamId, topic), content: content,
+          destination: StreamDestination(streamId, eg.t(topic)), content: content,
           readBySender: null,
           expectedBodyFields: {
             'type': 'stream',
@@ -406,7 +406,7 @@ void main() {
     test('legacy: when server does not support readBySender, sends a User-Agent the server will recognize', () {
       return FakeApiConnection.with_(zulipFeatureLevel: 235, (connection) async {
         await checkSendMessage(connection,
-          destination: const StreamDestination(streamId, topic), content: content,
+          destination: StreamDestination(streamId, eg.t(topic)), content: content,
           readBySender: true,
           expectedBodyFields: {
             'type': 'stream',
@@ -420,6 +420,67 @@ void main() {
     });
   });
 
+  group('updateMessage', () {
+    Future<UpdateMessageResult> checkUpdateMessage(
+      FakeApiConnection connection, {
+      required int messageId,
+      TopicName? topic,
+      PropagateMode? propagateMode,
+      bool? sendNotificationToOldThread,
+      bool? sendNotificationToNewThread,
+      String? content,
+      int? streamId,
+      required Map<String, String> expected,
+    }) async {
+      final result = await updateMessage(connection,
+        messageId: messageId,
+        topic: topic,
+        propagateMode: propagateMode,
+        sendNotificationToOldThread: sendNotificationToOldThread,
+        sendNotificationToNewThread: sendNotificationToNewThread,
+        content: content,
+        streamId: streamId,
+      );
+      check(connection.lastRequest).isA<http.Request>()
+        ..method.equals('PATCH')
+        ..url.path.equals('/api/v1/messages/$messageId')
+        ..bodyFields.deepEquals(expected);
+      return result;
+    }
+
+    test('topic/content change', () {
+      // A separate test exercises `streamId`;
+      // the API doesn't allow changing channel and content at the same time.
+      return FakeApiConnection.with_((connection) async {
+        connection.prepare(json: UpdateMessageResult().toJson());
+        await checkUpdateMessage(connection,
+          messageId: eg.streamMessage().id,
+          topic: eg.t('new topic'),
+          propagateMode: PropagateMode.changeAll,
+          sendNotificationToOldThread: true,
+          sendNotificationToNewThread: true,
+          content: 'asdf',
+          expected: {
+            'topic': 'new topic',
+            'propagate_mode': 'change_all',
+            'send_notification_to_old_thread': 'true',
+            'send_notification_to_new_thread': 'true',
+            'content': 'asdf',
+          });
+      });
+    });
+
+    test('channel change', () {
+      return FakeApiConnection.with_((connection) async {
+        connection.prepare(json: UpdateMessageResult().toJson());
+        await checkUpdateMessage(connection,
+          messageId: eg.streamMessage().id,
+          streamId: 1,
+          expected: {'stream_id': '1'});
+      });
+    });
+  });
+
   group('uploadFile', () {
     Future<void> checkUploadFile(FakeApiConnection connection, {
       required List<List<int>> content,
@@ -743,7 +804,7 @@ void main() {
     }) async {
       connection.prepare(json: {});
       await markTopicAsRead(connection,
-        streamId: streamId, topicName: topicName);
+        streamId: streamId, topicName: eg.t(topicName));
       check(connection.lastRequest).isA<http.Request>()
         ..method.equals('POST')
         ..url.path.equals('/api/v1/mark_topic_as_read')
diff --git a/test/api/route/typing_test.dart b/test/api/route/typing_test.dart
index 0d933e6f54..551f1a5a4e 100644
--- a/test/api/route/typing_test.dart
+++ b/test/api/route/typing_test.dart
@@ -4,6 +4,7 @@ import 'package:http/http.dart' as http;
 import 'package:checks/checks.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:zulip/api/model/events.dart';
+import 'package:zulip/api/model/model.dart';
 import 'package:zulip/api/route/messages.dart';
 import 'package:zulip/api/route/typing.dart';
 
@@ -31,7 +32,7 @@ void main() {
   Future<void> checkSetTypingStatusForTopic(TypingOp op, String expectedOp) {
     return FakeApiConnection.with_((connection) {
       return checkSetTypingStatus(connection, op,
-        destination: const StreamDestination(streamId, topic),
+        destination: const StreamDestination(streamId, TopicName(topic)),
         expectedBodyFields: {
           'op': expectedOp,
           'type': 'channel',
@@ -64,7 +65,7 @@ void main() {
   test('legacy: use "stream" instead of "channel"', () {
     return FakeApiConnection.with_(zulipFeatureLevel: 247, (connection) {
       return checkSetTypingStatus(connection, TypingOp.start,
-        destination: const StreamDestination(streamId, topic),
+        destination: const StreamDestination(streamId, TopicName(topic)),
         expectedBodyFields: {
           'op': 'start',
           'type': 'stream',
@@ -77,7 +78,7 @@ void main() {
   test('legacy: use to=[streamId] instead of stream_id=streamId', () {
     return FakeApiConnection.with_(zulipFeatureLevel: 214, (connection) {
       return checkSetTypingStatus(connection, TypingOp.start,
-        destination: const StreamDestination(streamId, topic),
+        destination: const StreamDestination(streamId, TopicName(topic)),
         expectedBodyFields: {
           'op': 'start',
           'type': 'stream',
diff --git a/test/example_data.dart b/test/example_data.dart
index d071307ec4..6b84bf185c 100644
--- a/test/example_data.dart
+++ b/test/example_data.dart
@@ -241,7 +241,8 @@ const _stream = stream;
 
 GetStreamTopicsEntry getStreamTopicsEntry({int? maxId, String? name}) {
   maxId ??= 123;
-  return GetStreamTopicsEntry(maxId: maxId, name: name ?? 'Test Topic #$maxId');
+  return GetStreamTopicsEntry(maxId: maxId,
+    name: TopicName(name ?? 'Test Topic #$maxId'));
 }
 
 /// Construct an example subscription from a stream.
@@ -283,11 +284,20 @@ Subscription subscription(
   );
 }
 
+/// The [TopicName] constructor, but shorter.
+///
+/// Useful in test code that mentions a lot of topics in a compact format.
+TopicName t(String apiName) => TopicName(apiName);
+
+TopicNarrow topicNarrow(int channelId, String topicName) {
+  return TopicNarrow(channelId, TopicName(topicName));
+}
+
 UserTopicItem userTopicItem(
     ZulipStream stream, String topic, UserTopicVisibilityPolicy policy) {
   return UserTopicItem(
     streamId: stream.streamId,
-    topicName: topic,
+    topicName: TopicName(topic),
     lastUpdated: 1234567890,
     visibilityPolicy: policy,
   );
@@ -519,6 +529,18 @@ Submessage submessage({
 // Aggregate data structures.
 //
 
+UnreadChannelSnapshot unreadChannelMsgs({
+  required String topic,
+  required int streamId,
+  required List<int> unreadMessageIds,
+}) {
+  return UnreadChannelSnapshot(
+    topic: TopicName(topic),
+    streamId: streamId,
+    unreadMessageIds: unreadMessageIds,
+  );
+}
+
 UnreadMessagesSnapshot unreadMsgs({
   int? count,
   List<UnreadDmSnapshot>? dms,
@@ -547,7 +569,7 @@ UserTopicEvent userTopicEvent(
   return UserTopicEvent(
     id: 1,
     streamId: streamId,
-    topicName: topic,
+    topicName: TopicName(topic),
     lastUpdated: 1234567890,
     visibilityPolicy: visibilityPolicy,
   );
@@ -605,8 +627,8 @@ UpdateMessageEvent _updateMessageMoveEvent(
   List<int> messageIds, {
   required int origStreamId,
   int? newStreamId,
-  required String origTopic,
-  String? newTopic,
+  required TopicName origTopic,
+  TopicName? newTopic,
   String? origContent,
   String? newContent,
   required List<MessageFlag> flags,
@@ -642,12 +664,15 @@ UpdateMessageEvent _updateMessageMoveEvent(
 UpdateMessageEvent updateMessageEventMoveFrom({
   required List<StreamMessage> origMessages,
   int? newStreamId,
-  String? newTopic,
+  TopicName? newTopic,
+  String? newTopicStr,
   String? newContent,
   PropagateMode propagateMode = PropagateMode.changeOne,
 }) {
   _checkPositive(newStreamId, 'stream ID');
   assert(origMessages.isNotEmpty);
+  assert(newTopic == null || newTopicStr == null);
+  newTopic ??= newTopicStr == null ? null : TopicName(newTopicStr);
   final origMessage = origMessages.first;
   // Only present on content change.
   final origContent = (newContent != null) ? origMessage.content : null;
@@ -667,12 +692,15 @@ UpdateMessageEvent updateMessageEventMoveFrom({
 UpdateMessageEvent updateMessageEventMoveTo({
   required List<StreamMessage> newMessages,
   int? origStreamId,
-  String? origTopic,
+  TopicName? origTopic,
+  String? origTopicStr,
   String? origContent,
   PropagateMode propagateMode = PropagateMode.changeOne,
 }) {
   _checkPositive(origStreamId, 'stream ID');
   assert(newMessages.isNotEmpty);
+  assert(origTopic == null || origTopicStr == null);
+  origTopic ??= origTopicStr == null ? null : TopicName(origTopicStr);
   final newMessage = newMessages.first;
   // Only present on topic move.
   final newTopic = (origTopic != null) ? newMessage.topic : null;
@@ -828,6 +856,8 @@ InitialSnapshot initialSnapshot({
   List<ZulipStream>? streams,
   UserSettings? userSettings,
   List<UserTopicItem>? userTopics,
+  RealmWildcardMentionPolicy? realmWildcardMentionPolicy,
+  bool? realmMandatoryTopics,
   int? realmWaitingPeriodThreshold,
   Map<String, RealmDefaultExternalAccount>? realmDefaultExternalAccounts,
   int? maxFileUploadSizeMib,
@@ -862,6 +892,8 @@ InitialSnapshot initialSnapshot({
       emojiset: Emojiset.google,
     ),
     userTopics: userTopics,
+    realmWildcardMentionPolicy: realmWildcardMentionPolicy ?? RealmWildcardMentionPolicy.everyone,
+    realmMandatoryTopics: realmMandatoryTopics ?? true,
     realmWaitingPeriodThreshold: realmWaitingPeriodThreshold ?? 0,
     realmDefaultExternalAccounts: realmDefaultExternalAccounts ?? {},
     maxFileUploadSizeMib: maxFileUploadSizeMib ?? 25,
diff --git a/test/flutter_checks.dart b/test/flutter_checks.dart
index 4e4ae7d986..505f5189f2 100644
--- a/test/flutter_checks.dart
+++ b/test/flutter_checks.dart
@@ -66,6 +66,12 @@ extension TextChecks on Subject<Text> {
   Subject<TextStyle?> get style => has((t) => t.style, 'style');
 }
 
+extension TextEditingValueChecks on Subject<TextEditingValue> {
+  Subject<String> get text => has((x) => x.text, 'text');
+  Subject<TextSelection> get selection => has((x) => x.selection, 'selection');
+  Subject<TextRange> get composing => has((x) => x.composing, 'composing');
+}
+
 extension TextEditingControllerChecks on Subject<TextEditingController> {
   Subject<String?> get text => has((t) => t.text, 'text');
 }
diff --git a/test/model/autocomplete_checks.dart b/test/model/autocomplete_checks.dart
index cb94735894..ec8acbe500 100644
--- a/test/model/autocomplete_checks.dart
+++ b/test/model/autocomplete_checks.dart
@@ -1,4 +1,5 @@
 import 'package:checks/checks.dart';
+import 'package:zulip/api/model/model.dart';
 import 'package:zulip/model/autocomplete.dart';
 import 'package:zulip/widgets/compose_box.dart';
 
@@ -20,5 +21,5 @@ extension UserMentionAutocompleteResultChecks on Subject<UserMentionAutocomplete
 }
 
 extension TopicAutocompleteResultChecks on Subject<TopicAutocompleteResult> {
-  Subject<String> get topic => has((r) => r.topic, 'topic');
+  Subject<TopicName> get topic => has((r) => r.topic, 'topic');
 }
diff --git a/test/model/autocomplete_test.dart b/test/model/autocomplete_test.dart
index 9d6667ca3f..da05030493 100644
--- a/test/model/autocomplete_test.dart
+++ b/test/model/autocomplete_test.dart
@@ -7,8 +7,11 @@ import 'package:test/scaffolding.dart';
 import 'package:zulip/api/model/initial_snapshot.dart';
 import 'package:zulip/api/model/model.dart';
 import 'package:zulip/api/route/channels.dart';
+import 'package:zulip/generated/l10n/zulip_localizations.dart';
 import 'package:zulip/model/autocomplete.dart';
+import 'package:zulip/model/compose.dart';
 import 'package:zulip/model/emoji.dart';
+import 'package:zulip/model/localizations.dart';
 import 'package:zulip/model/narrow.dart';
 import 'package:zulip/model/store.dart';
 import 'package:zulip/widgets/compose_box.dart';
@@ -21,6 +24,11 @@ import 'autocomplete_checks.dart';
 
 typedef MarkedTextParse = ({int? expectedSyntaxStart, TextEditingValue value});
 
+final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
+final zulipLocalizationsArabic =
+  lookupZulipLocalizations(ZulipLocalizations.supportedLocales
+    .firstWhere((locale) => locale.languageCode == 'ar'));
+
 void main() {
   ({int? expectedSyntaxStart, TextEditingValue value}) parseMarkedText(String markedText) {
     final TextSelection selection;
@@ -258,8 +266,8 @@ void main() {
     final store = eg.store();
     await store.addUsers([eg.selfUser, eg.otherUser, eg.thirdUser]);
 
-    final view = MentionAutocompleteView.init(store: store, narrow: narrow,
-      query: MentionAutocompleteQuery('Third'));
+    final view = MentionAutocompleteView.init(store: store, localizations: zulipLocalizations,
+      narrow: narrow, query: MentionAutocompleteQuery('Third'));
     bool done = false;
     view.addListener(() { done = true; });
     await Future(() {});
@@ -288,8 +296,8 @@ void main() {
         check(searchDone).isFalse();
       });
 
-      final view = MentionAutocompleteView.init(store: store, narrow: narrow,
-        query: MentionAutocompleteQuery('Third'));
+      final view = MentionAutocompleteView.init(store: store, localizations: zulipLocalizations,
+        narrow: narrow, query: MentionAutocompleteQuery('Third'));
       view.addListener(() {
         searchDone = true;
       });
@@ -312,8 +320,8 @@ void main() {
     }
 
     bool done = false;
-    final view = MentionAutocompleteView.init(store: store, narrow: narrow,
-      query: MentionAutocompleteQuery('User 2222'));
+    final view = MentionAutocompleteView.init(store: store, localizations: zulipLocalizations,
+      narrow: narrow, query: MentionAutocompleteQuery('User 2222'));
     view.addListener(() { done = true; });
 
     await Future(() {});
@@ -335,8 +343,8 @@ void main() {
     }
 
     bool done = false;
-    final view = MentionAutocompleteView.init(store: store, narrow: narrow,
-      query: MentionAutocompleteQuery('User 1111'));
+    final view = MentionAutocompleteView.init(store: store, localizations: zulipLocalizations,
+      narrow: narrow, query: MentionAutocompleteQuery('User 1111'));
     view.addListener(() { done = true; });
 
     await Future(() {});
@@ -370,8 +378,8 @@ void main() {
     }
 
     bool done = false;
-    final view = MentionAutocompleteView.init(store: store, narrow: narrow,
-      query: MentionAutocompleteQuery('User 110'));
+    final view = MentionAutocompleteView.init(store: store, localizations: zulipLocalizations,
+      narrow: narrow, query: MentionAutocompleteQuery('User 110'));
     view.addListener(() { done = true; });
 
     await Future(() {});
@@ -481,10 +489,11 @@ void main() {
       }
 
       int compareAB({required String? topic}) {
+        final realTopic = topic == null ? null : TopicName(topic);
         final resultAB = MentionAutocompleteView.compareByRecency(userA, userB,
-          streamId: stream.streamId, topic: topic, store: store);
+          streamId: stream.streamId, topic: realTopic, store: store);
         final resultBA = MentionAutocompleteView.compareByRecency(userB, userA,
-          streamId: stream.streamId, topic: topic, store: store);
+          streamId: stream.streamId, topic: realTopic, store: store);
         switch (resultAB) {
           case <0: check(resultBA).isGreaterThan(0);
           case >0: check(resultBA).isLessThan(0);
@@ -624,8 +633,8 @@ void main() {
 
     group('ranking across signals', () {
       void checkPrecedes(Narrow narrow, User userA, Iterable<User> usersB) {
-        final view = MentionAutocompleteView.init(store: store, narrow: narrow,
-          query: MentionAutocompleteQuery(''));
+        final view = MentionAutocompleteView.init(store: store, localizations: zulipLocalizations,
+          narrow: narrow, query: MentionAutocompleteQuery(''));
         for (final userB in usersB) {
           check(view.debugCompareUsers(userA, userB)).isLessThan(0);
           check(view.debugCompareUsers(userB, userA)).isGreaterThan(0);
@@ -633,8 +642,8 @@ void main() {
       }
 
       void checkRankEqual(Narrow narrow, List<User> users) {
-        final view = MentionAutocompleteView.init(store: store, narrow: narrow,
-          query: MentionAutocompleteQuery(''));
+        final view = MentionAutocompleteView.init(store: store, localizations: zulipLocalizations,
+          narrow: narrow, query: MentionAutocompleteQuery(''));
         for (int i = 0; i < users.length; i++) {
           for (int j = i + 1; j < users.length; j++) {
             check(view.debugCompareUsers(users[i], users[j])).equals(0);
@@ -659,7 +668,7 @@ void main() {
           eg.user(fullName: 'b', isBot: true),
         ];
         final stream = eg.stream();
-        final narrow = TopicNarrow(stream.streamId, 'this');
+        final narrow = eg.topicNarrow(stream.streamId, 'this');
         await prepare(users: users, messages: [
           eg.streamMessage(sender: users[1], stream: stream, topic: 'this'),
           eg.streamMessage(sender: users[0], stream: stream, topic: 'this'),
@@ -751,46 +760,51 @@ void main() {
       test('CombinedFeedNarrow gives error', () async {
         await prepare(users: [eg.user(), eg.user()], messages: []);
         const narrow = CombinedFeedNarrow();
-        check(() => MentionAutocompleteView.init(store: store, narrow: narrow,
-                      query: MentionAutocompleteQuery('')))
+        check(() => MentionAutocompleteView.init(store: store, localizations: zulipLocalizations,
+                      narrow: narrow, query: MentionAutocompleteQuery('')))
           .throws<AssertionError>();
       });
 
       test('MentionsNarrow gives error', () async {
         await prepare(users: [eg.user(), eg.user()], messages: []);
         const narrow = MentionsNarrow();
-        check(() => MentionAutocompleteView.init(store: store, narrow: narrow,
-                      query: MentionAutocompleteQuery('')))
+        check(() => MentionAutocompleteView.init(store: store, localizations: zulipLocalizations,
+                      narrow: narrow, query: MentionAutocompleteQuery('')))
           .throws<AssertionError>();
       });
 
       test('StarredMessagesNarrow gives error', () async {
         await prepare(users: [eg.user(), eg.user()], messages: []);
         const narrow = StarredMessagesNarrow();
-        check(() => MentionAutocompleteView.init(store: store, narrow: narrow,
-                      query: MentionAutocompleteQuery('')))
+        check(() => MentionAutocompleteView.init(store: store, localizations: zulipLocalizations,
+                      narrow: narrow, query: MentionAutocompleteQuery('')))
           .throws<AssertionError>();
       });
     });
 
     test('final results end-to-end', () async {
-      Future<Iterable<int>> getResults(
+      Future<Iterable<MentionAutocompleteResult>> getResults(
           Narrow narrow, MentionAutocompleteQuery query) async {
         bool done = false;
-        final view = MentionAutocompleteView.init(store: store, narrow: narrow,
-          query: query);
+        final view = MentionAutocompleteView.init(store: store,
+          localizations: zulipLocalizations, narrow: narrow, query: query);
         view.addListener(() { done = true; });
         await Future(() {});
         check(done).isTrue();
-        final results = view.results
-          .map((e) => (e as UserMentionAutocompleteResult).userId);
+        final results = view.results;
         view.dispose();
         return results;
       }
 
+      Iterable<int> getUsersFromResults(Iterable<MentionAutocompleteResult> results)
+        => results.map((e) => (e as UserMentionAutocompleteResult).userId);
+
+      Iterable<WildcardMentionOption> getWildcardOptionsFromResults(Iterable<MentionAutocompleteResult> results)
+        => results.map((e) => (e as WildcardMentionAutocompleteResult).wildcardOption);
+
       final stream = eg.stream();
       const topic = 'topic';
-      final topicNarrow = TopicNarrow(stream.streamId, topic);
+      final topicNarrow = eg.topicNarrow(stream.streamId, topic);
 
       final users = [
         eg.user(userId: 1, fullName: 'User One'),
@@ -811,20 +825,133 @@ void main() {
         RecentDmConversation(userIds: [1, 2], maxMessageId: 100),
       ]);
 
-      // Check the ranking of the full list of users.
+      // Check the ranking of the full list of mentions.
       // The order should be:
-      // 1. Users most recent in the current topic/stream.
-      // 2. Users most recent in the DM conversations.
-      // 3. Human vs. Bot users (human users come first).
-      // 4. Alphabetical order by name.
-      check(await getResults(topicNarrow, MentionAutocompleteQuery('')))
+      // 1. Wildcards before individual users.
+      // 2. Users most recent in the current topic/stream.
+      // 3. Users most recent in the DM conversations.
+      // 4. Human vs. Bot users (human users come first).
+      // 5. Users by name alphabetical order.
+      final results1 = await getResults(topicNarrow, MentionAutocompleteQuery(''));
+      check(getWildcardOptionsFromResults(results1.take(2)))
+        .deepEquals([WildcardMentionOption.all, WildcardMentionOption.topic]);
+      check(getUsersFromResults(results1.skip(2)))
         .deepEquals([1, 5, 4, 2, 7, 3, 6]);
 
       // Check the ranking applies also to results filtered by a query.
-      check(await getResults(topicNarrow, MentionAutocompleteQuery('t')))
-        .deepEquals([2, 3]);
-      check(await getResults(topicNarrow, MentionAutocompleteQuery('f')))
-        .deepEquals([5, 4]);
+      final results2 = await getResults(topicNarrow, MentionAutocompleteQuery('t'));
+      check(getWildcardOptionsFromResults(results2.take(2)))
+        .deepEquals([WildcardMentionOption.stream, WildcardMentionOption.topic]);
+      check(getUsersFromResults(results2.skip(2))).deepEquals([2, 3]);
+      final results3 = await getResults(topicNarrow, MentionAutocompleteQuery('f'));
+      check(getWildcardOptionsFromResults(results3.take(0))).deepEquals([]);
+      check(getUsersFromResults(results3.skip(0))).deepEquals([5, 4]);
+    });
+  });
+
+  group('MentionAutocompleteView.computeWildcardMentionResults', () {
+    Iterable<WildcardMentionOption> getWildcardOptionsFor(String rawQuery, {
+      bool isSilent = false,
+      required Narrow narrow,
+      int? zulipFeatureLevel,
+      ZulipLocalizations? localizations,
+    }) {
+      final store = eg.store(
+        account: eg.account(user: eg.selfUser, zulipFeatureLevel: zulipFeatureLevel),
+        initialSnapshot: eg.initialSnapshot(zulipFeatureLevel: zulipFeatureLevel));
+      localizations ??= zulipLocalizations;
+      final view = MentionAutocompleteView.init(store: store, localizations: localizations,
+        narrow: narrow, query: MentionAutocompleteQuery(rawQuery, silent: isSilent));
+      final results = <MentionAutocompleteResult>[];
+      view.computeWildcardMentionResults(results: results,
+        isComposingChannelMessage: narrow is ChannelNarrow
+          || narrow is TopicNarrow);
+      view.dispose();
+      return results.map((e) => (e as WildcardMentionAutocompleteResult).wildcardOption);
+    }
+
+    const channelNarrow = ChannelNarrow(1);
+    const topicNarrow = TopicNarrow(1, TopicName('topic'));
+    final dmNarrow = DmNarrow.withUser(10, selfUserId: 5);
+
+    final testCases = [
+      ('',          channelNarrow, [WildcardMentionOption.all, WildcardMentionOption.topic]),
+      ('',          topicNarrow,   [WildcardMentionOption.all, WildcardMentionOption.topic]),
+      ('',          dmNarrow,      [WildcardMentionOption.all]),
+
+      ('c',         channelNarrow, [WildcardMentionOption.channel, WildcardMentionOption.topic]),
+      ('ch',        topicNarrow,   [WildcardMentionOption.channel]),
+      ('str',       channelNarrow, [WildcardMentionOption.stream]),
+      ('e',         topicNarrow,   [WildcardMentionOption.everyone]),
+      ('everyone',  channelNarrow, [WildcardMentionOption.everyone]),
+      ('t',         topicNarrow,   [WildcardMentionOption.stream, WildcardMentionOption.topic]),
+      ('topic',     channelNarrow, [WildcardMentionOption.topic]),
+      ('topic etc', topicNarrow,   <WildcardMentionOption>[]),
+
+      ('a',         dmNarrow,      [WildcardMentionOption.all]),
+      ('every',     dmNarrow,      [WildcardMentionOption.everyone]),
+      ('channel',   dmNarrow,      <WildcardMentionOption>[]),
+      ('stream',    dmNarrow,      <WildcardMentionOption>[]),
+      ('topic',     dmNarrow,      <WildcardMentionOption>[]),
+    ];
+
+    for (final (String query, Narrow narrow, List<WildcardMentionOption> wildcardOptions) in testCases) {
+      test('query "$query" in ${narrow.runtimeType} -> $wildcardOptions', () async {
+        check(getWildcardOptionsFor(query, narrow: narrow)).deepEquals(wildcardOptions);
+      });
+    }
+
+    final localizedTestCases = [
+      ('ال',        channelNarrow, [WildcardMentionOption.all, WildcardMentionOption.topic]),
+      ('الجميع',    topicNarrow,   [WildcardMentionOption.all]),
+      ('الموضوع',   channelNarrow, [WildcardMentionOption.topic]),
+      ('ق',         topicNarrow,   [WildcardMentionOption.channel]),
+      ('دفق',       channelNarrow, [WildcardMentionOption.stream]),
+      ('الكل',      dmNarrow,      [WildcardMentionOption.everyone]),
+
+      ('top',       channelNarrow, [WildcardMentionOption.topic]),
+      ('channel',   topicNarrow,   [WildcardMentionOption.channel]),
+      ('every',     dmNarrow,      [WildcardMentionOption.everyone]),
+    ];
+
+    for (final (String localizedQuery, Narrow narrow, List<WildcardMentionOption> wildcardOptions) in localizedTestCases) {
+      test('different locale -> query "$localizedQuery" in ${narrow.runtimeType} -> $wildcardOptions', () async {
+        check(getWildcardOptionsFor(localizedQuery, narrow: narrow,
+          localizations: zulipLocalizationsArabic)).deepEquals(wildcardOptions);
+      });
+    }
+
+    test('no wildcards for a silent mention', () {
+      check(getWildcardOptionsFor('', isSilent: true, narrow: channelNarrow))
+        .isEmpty();
+      check(getWildcardOptionsFor('all', isSilent: true, narrow: topicNarrow))
+        .isEmpty();
+      check(getWildcardOptionsFor('everyone', isSilent: true, narrow: dmNarrow))
+        .isEmpty();
+    });
+
+    test('${WildcardMentionOption.channel} is available FL-247 onwards', () {
+      check(getWildcardOptionsFor('channel',
+          narrow: channelNarrow, zulipFeatureLevel: 247))
+        .deepEquals([WildcardMentionOption.channel]);
+    });
+
+    test('${WildcardMentionOption.channel} is not available before FL-247', () {
+      check(getWildcardOptionsFor('channel',
+          narrow: channelNarrow, zulipFeatureLevel: 246))
+        .deepEquals([]);
+    });
+
+    test('${WildcardMentionOption.topic} is available FL-224 onwards', () {
+      check(getWildcardOptionsFor('topic',
+          narrow: channelNarrow, zulipFeatureLevel: 224))
+        .deepEquals([WildcardMentionOption.topic]);
+    });
+
+    test('${WildcardMentionOption.topic} is not available before FL-224', () {
+      check(getWildcardOptionsFor('topic',
+          narrow: channelNarrow, zulipFeatureLevel: 223))
+        .deepEquals([]);
     });
   });
 
@@ -834,7 +961,8 @@ void main() {
 
       final description = 'topic-input with text: $markedText produces: ${expectedQuery?.raw ?? 'No Query!'}';
       test(description, () {
-        final controller = ComposeTopicController();
+        final store = eg.store();
+        final controller = ComposeTopicController(store: store);
         controller.value = parsed.value;
         if (expectedQuery == null) {
           check(controller).autocompleteIntent.isNull();
@@ -900,7 +1028,7 @@ void main() {
 
   group('TopicAutocompleteQuery.testTopic', () {
     void doCheck(String rawQuery, String topic, bool expected) {
-      final result = TopicAutocompleteQuery(rawQuery).testTopic(topic);
+      final result = TopicAutocompleteQuery(rawQuery).testTopic(eg.t(topic));
       expected ? check(result).isTrue() : check(result).isFalse();
     }
 
diff --git a/test/model/binding.dart b/test/model/binding.dart
index badbbcf7e0..039d6c3787 100644
--- a/test/model/binding.dart
+++ b/test/model/binding.dart
@@ -4,6 +4,7 @@ import 'package:clock/clock.dart';
 import 'package:firebase_core/firebase_core.dart';
 import 'package:firebase_messaging/firebase_messaging.dart';
 import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
 import 'package:test/fake.dart';
 import 'package:url_launcher/url_launcher.dart' as url_launcher;
 import 'package:zulip/host/android_notifications.dart';
@@ -398,6 +399,7 @@ class FakeFirebaseMessaging extends Fake implements FirebaseMessaging {
     timeSensitive: AppleNotificationSetting.disabled,
     criticalAlert: AppleNotificationSetting.disabled,
     sound: AppleNotificationSetting.enabled,
+    providesAppNotificationSettings: AppleNotificationSetting.disabled,
   );
 
   List<FirebaseMessagingRequestPermissionCall> takeRequestPermissionCalls() {
@@ -416,6 +418,7 @@ class FakeFirebaseMessaging extends Fake implements FirebaseMessaging {
     bool criticalAlert = false,
     bool provisional = false,
     bool sound = true,
+    bool providesAppNotificationSettings = false,
   }) async {
     _requestPermissionCalls.add((
       alert: alert,
@@ -425,6 +428,7 @@ class FakeFirebaseMessaging extends Fake implements FirebaseMessaging {
       criticalAlert: criticalAlert,
       provisional: provisional,
       sound: sound,
+      providesAppNotificationSettings: providesAppNotificationSettings,
     ));
     return requestPermissionResult;
   }
@@ -505,9 +509,24 @@ typedef FirebaseMessagingRequestPermissionCall = ({
   bool criticalAlert,
   bool provisional,
   bool sound,
+  bool providesAppNotificationSettings,
 });
 
 class FakeAndroidNotificationHostApi implements AndroidNotificationHostApi {
+  // TODO(?): Find a better way to handle this. This member is exported from
+  //   the Pigeon generated class but are not used for this fake class,
+  //   so return the default value.
+  @override
+  // ignore: non_constant_identifier_names
+  final BinaryMessenger? pigeonVar_binaryMessenger = null;
+
+  // TODO(?): Find a better way to handle this. This member is exported from
+  //   the Pigeon generated class but are not used for this fake class,
+  //   so return the default value.
+  @override
+  // ignore: non_constant_identifier_names
+  final String pigeonVar_messageChannelSuffix = '';
+
   /// Lists currently active channels, result is aggregated from calls made to
   /// [createNotificationChannel] and [deleteNotificationChannel],
   /// order of creation is preserved.
@@ -532,7 +551,7 @@ class FakeAndroidNotificationHostApi implements AndroidNotificationHostApi {
   }
 
   @override
-  Future<List<NotificationChannel?>> getNotificationChannels() async {
+  Future<List<NotificationChannel>> getNotificationChannels() async {
     return _activeChannels.values.toList(growable: false);
   }
 
@@ -567,7 +586,7 @@ class FakeAndroidNotificationHostApi implements AndroidNotificationHostApi {
   }
 
   @override
-  Future<List<StoredNotificationSound?>> listStoredSoundsInNotificationsDirectory() async {
+  Future<List<StoredNotificationSound>> listStoredSoundsInNotificationsDirectory() async {
     return _storedNotificationSounds.toList(growable: false);
   }
 
@@ -631,7 +650,7 @@ class FakeAndroidNotificationHostApi implements AndroidNotificationHostApi {
     PendingIntent? contentIntent,
     String? contentText,
     String? contentTitle,
-    Map<String?, String?>? extras,
+    Map<String, String>? extras,
     String? groupKey,
     InboxStyle? inboxStyle,
     bool? isGroupSummary,
@@ -671,7 +690,7 @@ class FakeAndroidNotificationHostApi implements AndroidNotificationHostApi {
             isGroupConversation: messagingStyle.isGroupConversation,
             messages: messagingStyle.messages.map((message) =>
               MessagingStyleMessage(
-                text: message!.text,
+                text: message.text,
                 timestampMs: message.timestampMs,
                 person: Person(
                   key: message.person.key,
@@ -686,14 +705,14 @@ class FakeAndroidNotificationHostApi implements AndroidNotificationHostApi {
     _activeNotificationsMessagingStyle[tag];
 
   @override
-  Future<List<StatusBarNotification?>> getActiveNotifications({required List<String?> desiredExtras}) async {
+  Future<List<StatusBarNotification>> getActiveNotifications({required List<String> desiredExtras}) async {
     return _activeNotifications.values.map((statusNotif) {
       final notificationExtras = statusNotif.notification.extras;
-      statusNotif.notification.extras = Map.fromEntries(
-        desiredExtras
-          .map((key) => MapEntry(key, notificationExtras[key]))
-          .where((entry) => entry.value != null)
-      );
+      statusNotif.notification.extras = {
+        for (final key in desiredExtras)
+          if (notificationExtras[key] != null)
+            key: notificationExtras[key]!,
+      };
       return statusNotif;
     }).toList(growable: false);
   }
diff --git a/test/model/channel_test.dart b/test/model/channel_test.dart
index 14a9f69ea3..f22ac7cc8f 100644
--- a/test/model/channel_test.dart
+++ b/test/model/channel_test.dart
@@ -123,14 +123,14 @@ void main() {
     group('getter topicVisibilityPolicy', () {
       test('with nothing for stream', () {
         final store = eg.store();
-        check(store.topicVisibilityPolicy(stream1.streamId, 'topic'))
+        check(store.topicVisibilityPolicy(stream1.streamId, eg.t('topic')))
           .equals(UserTopicVisibilityPolicy.none);
       });
 
       test('with nothing for topic', () async {
         final store = eg.store();
         await store.addUserTopic(stream1, 'other topic', UserTopicVisibilityPolicy.muted);
-        check(store.topicVisibilityPolicy(stream1.streamId, 'topic'))
+        check(store.topicVisibilityPolicy(stream1.streamId, eg.t('topic')))
           .equals(UserTopicVisibilityPolicy.none);
       });
 
@@ -142,7 +142,7 @@ void main() {
           UserTopicVisibilityPolicy.followed,
         ]) {
           await store.addUserTopic(stream1, 'topic', policy);
-          check(store.topicVisibilityPolicy(stream1.streamId, 'topic'))
+          check(store.topicVisibilityPolicy(stream1.streamId, eg.t('topic')))
             .equals(policy);
         }
       });
@@ -153,23 +153,23 @@ void main() {
         final store = eg.store();
         await store.addStream(stream1);
         await store.addSubscription(eg.subscription(stream1));
-        check(store.isTopicVisibleInStream(stream1.streamId, 'topic')).isTrue();
-        check(store.isTopicVisible        (stream1.streamId, 'topic')).isTrue();
+        check(store.isTopicVisibleInStream(stream1.streamId, eg.t('topic'))).isTrue();
+        check(store.isTopicVisible        (stream1.streamId, eg.t('topic'))).isTrue();
       });
 
       test('with policy none, stream muted', () async {
         final store = eg.store();
         await store.addStream(stream1);
         await store.addSubscription(eg.subscription(stream1, isMuted: true));
-        check(store.isTopicVisibleInStream(stream1.streamId, 'topic')).isTrue();
-        check(store.isTopicVisible        (stream1.streamId, 'topic')).isFalse();
+        check(store.isTopicVisibleInStream(stream1.streamId, eg.t('topic'))).isTrue();
+        check(store.isTopicVisible        (stream1.streamId, eg.t('topic'))).isFalse();
       });
 
       test('with policy none, stream unsubscribed', () async {
         final store = eg.store();
         await store.addStream(stream1);
-        check(store.isTopicVisibleInStream(stream1.streamId, 'topic')).isTrue();
-        check(store.isTopicVisible        (stream1.streamId, 'topic')).isFalse();
+        check(store.isTopicVisibleInStream(stream1.streamId, eg.t('topic'))).isTrue();
+        check(store.isTopicVisible        (stream1.streamId, eg.t('topic'))).isFalse();
       });
 
       test('with policy muted', () async {
@@ -177,8 +177,8 @@ void main() {
         await store.addStream(stream1);
         await store.addSubscription(eg.subscription(stream1));
         await store.addUserTopic(stream1, 'topic', UserTopicVisibilityPolicy.muted);
-        check(store.isTopicVisibleInStream(stream1.streamId, 'topic')).isFalse();
-        check(store.isTopicVisible        (stream1.streamId, 'topic')).isFalse();
+        check(store.isTopicVisibleInStream(stream1.streamId, eg.t('topic'))).isFalse();
+        check(store.isTopicVisible        (stream1.streamId, eg.t('topic'))).isFalse();
       });
 
       test('with policy unmuted', () async {
@@ -186,8 +186,8 @@ void main() {
         await store.addStream(stream1);
         await store.addSubscription(eg.subscription(stream1, isMuted: true));
         await store.addUserTopic(stream1, 'topic', UserTopicVisibilityPolicy.unmuted);
-        check(store.isTopicVisibleInStream(stream1.streamId, 'topic')).isTrue();
-        check(store.isTopicVisible        (stream1.streamId, 'topic')).isTrue();
+        check(store.isTopicVisibleInStream(stream1.streamId, eg.t('topic'))).isTrue();
+        check(store.isTopicVisible        (stream1.streamId, eg.t('topic'))).isTrue();
       });
 
       test('with policy followed', () async {
@@ -195,8 +195,8 @@ void main() {
         await store.addStream(stream1);
         await store.addSubscription(eg.subscription(stream1, isMuted: true));
         await store.addUserTopic(stream1, 'topic', UserTopicVisibilityPolicy.followed);
-        check(store.isTopicVisibleInStream(stream1.streamId, 'topic')).isTrue();
-        check(store.isTopicVisible        (stream1.streamId, 'topic')).isTrue();
+        check(store.isTopicVisibleInStream(stream1.streamId, eg.t('topic'))).isTrue();
+        check(store.isTopicVisible        (stream1.streamId, eg.t('topic'))).isTrue();
       });
     });
 
@@ -265,16 +265,16 @@ void main() {
                   eg.subscription(stream1, isMuted: streamMuted));
               }
               await store.handleEvent(mkEvent(oldPolicy));
-              final oldVisibleInStream = store.isTopicVisibleInStream(stream1.streamId, 'topic');
-              final oldVisible         = store.isTopicVisible(stream1.streamId, 'topic');
+              final oldVisibleInStream = store.isTopicVisibleInStream(stream1.streamId, eg.t('topic'));
+              final oldVisible         = store.isTopicVisible(stream1.streamId, eg.t('topic'));
 
               final event = mkEvent(newPolicy);
               final willChangeInStream = store.willChangeIfTopicVisibleInStream(event);
               final willChange         = store.willChangeIfTopicVisible(event);
 
               await store.handleEvent(event);
-              final newVisibleInStream = store.isTopicVisibleInStream(stream1.streamId, 'topic');
-              final newVisible         = store.isTopicVisible(stream1.streamId, 'topic');
+              final newVisibleInStream = store.isTopicVisibleInStream(stream1.streamId, eg.t('topic'));
+              final newVisible         = store.isTopicVisible(stream1.streamId, eg.t('topic'));
 
               VisibilityEffect fromOldNew(bool oldVisible, bool newVisible) {
                 if (newVisible == oldVisible) return VisibilityEffect.none;
@@ -384,13 +384,13 @@ void main() {
           eg.userTopicItem(stream, 'topic 2', UserTopicVisibilityPolicy.unmuted),
           eg.userTopicItem(stream, 'topic 3', UserTopicVisibilityPolicy.followed),
         ]));
-      check(store.topicVisibilityPolicy(stream.streamId, 'topic 1'))
+      check(store.topicVisibilityPolicy(stream.streamId, eg.t('topic 1')))
         .equals(UserTopicVisibilityPolicy.muted);
-      check(store.topicVisibilityPolicy(stream.streamId, 'topic 2'))
+      check(store.topicVisibilityPolicy(stream.streamId, eg.t('topic 2')))
         .equals(UserTopicVisibilityPolicy.unmuted);
-      check(store.topicVisibilityPolicy(stream.streamId, 'topic 3'))
+      check(store.topicVisibilityPolicy(stream.streamId, eg.t('topic 3')))
         .equals(UserTopicVisibilityPolicy.followed);
-      check(store.topicVisibilityPolicy(stream.streamId, 'topic 4'))
+      check(store.topicVisibilityPolicy(stream.streamId, eg.t('topic 4')))
         .equals(UserTopicVisibilityPolicy.none);
     });
   });
diff --git a/test/model/compose_test.dart b/test/model/compose_test.dart
index 9d6387cd5c..73fa9452d7 100644
--- a/test/model/compose_test.dart
+++ b/test/model/compose_test.dart
@@ -1,6 +1,8 @@
 import 'package:checks/checks.dart';
 import 'package:test/scaffolding.dart';
 import 'package:zulip/model/compose.dart';
+import 'package:zulip/model/localizations.dart';
+import 'package:zulip/model/store.dart';
 
 import '../example_data.dart' as eg;
 import 'test_store.dart';
@@ -221,27 +223,54 @@ hello
   });
 
   group('mention', () {
-    final user = eg.user(userId: 123, fullName: 'Full Name');
-    test('not silent', () {
-      check(mention(user, silent: false)).equals('@**Full Name|123**');
+    group('user', () {
+      final user = eg.user(userId: 123, fullName: 'Full Name');
+      test('not silent', () {
+        check(userMention(user, silent: false)).equals('@**Full Name|123**');
+      });
+      test('silent', () {
+        check(userMention(user, silent: true)).equals('@_**Full Name|123**');
+      });
+      test('`users` passed; has two users with same fullName', () async {
+        final store = eg.store();
+        await store.addUsers([user, eg.user(userId: 5), eg.user(userId: 234, fullName: user.fullName)]);
+        check(userMention(user, silent: true, users: store.users)).equals('@_**Full Name|123**');
+      });
+      test('`users` passed; has two same-name users but one of them is deactivated', () async {
+        final store = eg.store();
+        await store.addUsers([user, eg.user(userId: 5), eg.user(userId: 234, fullName: user.fullName, isActive: false)]);
+        check(userMention(user, silent: true, users: store.users)).equals('@_**Full Name|123**');
+      });
+      test('`users` passed; user has unique fullName', () async {
+        final store = eg.store();
+        await store.addUsers([user, eg.user(userId: 234, fullName: 'Another Name')]);
+        check(userMention(user, silent: true, users: store.users)).equals('@_**Full Name**');
+      });
     });
-    test('silent', () {
-      check(mention(user, silent: true)).equals('@_**Full Name|123**');
-    });
-    test('`users` passed; has two users with same fullName', () async {
-      final store = eg.store();
-      await store.addUsers([user, eg.user(userId: 5), eg.user(userId: 234, fullName: user.fullName)]);
-      check(mention(user, silent: true, users: store.users)).equals('@_**Full Name|123**');
-    });
-    test('`users` passed; has two same-name users but one of them is deactivated', () async {
-      final store = eg.store();
-      await store.addUsers([user, eg.user(userId: 5), eg.user(userId: 234, fullName: user.fullName, isActive: false)]);
-      check(mention(user, silent: true, users: store.users)).equals('@_**Full Name|123**');
-    });
-    test('`users` passed; user has unique fullName', () async {
-      final store = eg.store();
-      await store.addUsers([user, eg.user(userId: 234, fullName: 'Another Name')]);
-      check(mention(user, silent: true, users: store.users)).equals('@_**Full Name**');
+
+    test('wildcard', () {
+      PerAccountStore store({int? zulipFeatureLevel}) {
+        return eg.store(
+          account: eg.account(user: eg.selfUser,
+            zulipFeatureLevel: zulipFeatureLevel),
+          initialSnapshot: eg.initialSnapshot(
+            zulipFeatureLevel: zulipFeatureLevel));
+      }
+
+      check(wildcardMention(WildcardMentionOption.all, store: store()))
+        .equals('@**all**');
+      check(wildcardMention(WildcardMentionOption.everyone, store: store()))
+        .equals('@**everyone**');
+      check(wildcardMention(WildcardMentionOption.channel, store: store()))
+        .equals('@**channel**');
+      check(wildcardMention(WildcardMentionOption.stream,
+          store: store(zulipFeatureLevel: 247)))
+        .equals('@**channel**');
+      check(wildcardMention(WildcardMentionOption.stream,
+          store: store(zulipFeatureLevel: 246)))
+        .equals('@**stream**');
+      check(wildcardMention(WildcardMentionOption.topic, store: store()))
+        .equals('@**topic**');
     });
   });
 
@@ -260,7 +289,8 @@ hello
     await store.addStream(stream);
     await store.addUser(sender);
 
-    check(quoteAndReplyPlaceholder(store, message: message)).equals('''
+    check(quoteAndReplyPlaceholder(
+      GlobalLocalizations.zulipLocalizations, store, message: message)).equals('''
 @_**Full Name|123** [said](${eg.selfAccount.realmUrl}#narrow/stream/1-test-here/topic/some.20topic/near/${message.id}): *(loading message ${message.id})*
 ''');
 
diff --git a/test/model/internal_link_test.dart b/test/model/internal_link_test.dart
index 3949339321..eb91e35855 100644
--- a/test/model/internal_link_test.dart
+++ b/test/model/internal_link_test.dart
@@ -72,7 +72,7 @@ void main() {
         await store.addStream(eg.stream(streamId: streamId, name: name));
         final narrow = topic == null
           ? ChannelNarrow(streamId)
-          : TopicNarrow(streamId, topic);
+          : eg.topicNarrow(streamId, topic);
         check(narrowLink(store, narrow, nearMessageId: nearMessageId))
           .equals(store.realmUrl.resolve(expectedFragment));
       }
@@ -281,28 +281,28 @@ void main() {
     });
 
     group('"/#narrow/stream/<...>/topic/<...>" returns expected TopicNarrow', () {
-      const testCases = [
-        ('/#narrow/stream/check/topic/test',                 TopicNarrow(1, 'test')),
-        ('/#narrow/stream/mobile/subject/topic/near/378333', TopicNarrow(3, 'topic')),
-        ('/#narrow/stream/mobile/subject/topic/with/1',      TopicNarrow(3, 'topic')),
-        ('/#narrow/stream/mobile/topic/topic/',              TopicNarrow(3, 'topic')),
-        ('/#narrow/stream/stream/topic/topic/near/1',        TopicNarrow(5, 'topic')),
-        ('/#narrow/stream/stream/topic/topic/with/22',       TopicNarrow(5, 'topic')),
-        ('/#narrow/stream/stream/subject/topic/near/1',      TopicNarrow(5, 'topic')),
-        ('/#narrow/stream/stream/subject/topic/with/333',    TopicNarrow(5, 'topic')),
-        ('/#narrow/stream/stream/subject/topic',             TopicNarrow(5, 'topic')),
+      final testCases = [
+        ('/#narrow/stream/check/topic/test',                 eg.topicNarrow(1, 'test')),
+        ('/#narrow/stream/mobile/subject/topic/near/378333', eg.topicNarrow(3, 'topic')),
+        ('/#narrow/stream/mobile/subject/topic/with/1',      eg.topicNarrow(3, 'topic')),
+        ('/#narrow/stream/mobile/topic/topic/',              eg.topicNarrow(3, 'topic')),
+        ('/#narrow/stream/stream/topic/topic/near/1',        eg.topicNarrow(5, 'topic')),
+        ('/#narrow/stream/stream/topic/topic/with/22',       eg.topicNarrow(5, 'topic')),
+        ('/#narrow/stream/stream/subject/topic/near/1',      eg.topicNarrow(5, 'topic')),
+        ('/#narrow/stream/stream/subject/topic/with/333',    eg.topicNarrow(5, 'topic')),
+        ('/#narrow/stream/stream/subject/topic',             eg.topicNarrow(5, 'topic')),
       ];
       testExpectedNarrows(testCases, streams: streams);
     });
 
     group('Both `stream` and `channel` can be used interchangeably', () {
-      const testCases = [
-        ('/#narrow/stream/check',                         ChannelNarrow(1)),
-        ('/#narrow/channel/check',                        ChannelNarrow(1)),
-        ('/#narrow/stream/check/topic/test',              TopicNarrow(1, 'test')),
-        ('/#narrow/channel/check/topic/test',             TopicNarrow(1, 'test')),
-        ('/#narrow/stream/check/topic/test/near/378333',  TopicNarrow(1, 'test')),
-        ('/#narrow/channel/check/topic/test/near/378333', TopicNarrow(1, 'test')),
+      final testCases = [
+        ('/#narrow/stream/check',                         const ChannelNarrow(1)),
+        ('/#narrow/channel/check',                        const ChannelNarrow(1)),
+        ('/#narrow/stream/check/topic/test',              eg.topicNarrow(1, 'test')),
+        ('/#narrow/channel/check/topic/test',             eg.topicNarrow(1, 'test')),
+        ('/#narrow/stream/check/topic/test/near/378333',  eg.topicNarrow(1, 'test')),
+        ('/#narrow/channel/check/topic/test/near/378333', eg.topicNarrow(1, 'test')),
       ];
       testExpectedNarrows(testCases, streams: streams);
     });
@@ -414,13 +414,13 @@ void main() {
         eg.stream(streamId: 2, name: 'some stream'),
         eg.stream(streamId: 3, name: 'some.stream'),
       ];
-      const testCases = [
-        ('/#narrow/stream/some_stream',                    ChannelNarrow(1)),
-        ('/#narrow/stream/some.20stream',                  ChannelNarrow(2)),
-        ('/#narrow/stream/some.2Estream',                  ChannelNarrow(3)),
-        ('/#narrow/stream/some_stream/topic/some_topic',   TopicNarrow(1, 'some_topic')),
-        ('/#narrow/stream/some_stream/topic/some.20topic', TopicNarrow(1, 'some topic')),
-        ('/#narrow/stream/some_stream/topic/some.2Etopic', TopicNarrow(1, 'some.topic')),
+      final testCases = [
+        ('/#narrow/stream/some_stream',                    const ChannelNarrow(1)),
+        ('/#narrow/stream/some.20stream',                  const ChannelNarrow(2)),
+        ('/#narrow/stream/some.2Estream',                  const ChannelNarrow(3)),
+        ('/#narrow/stream/some_stream/topic/some_topic',   eg.topicNarrow(1, 'some_topic')),
+        ('/#narrow/stream/some_stream/topic/some.20topic', eg.topicNarrow(1, 'some topic')),
+        ('/#narrow/stream/some_stream/topic/some.2Etopic', eg.topicNarrow(1, 'some.topic')),
       ];
       testExpectedNarrows(testCases, streams: streams);
     });
@@ -518,8 +518,8 @@ void main() {
           return '#narrow/stream/${stream.streamId}-${stream.name}/topic/$operand';
         }
         final testCases = [
-          (mkUrlString('(no.20topic)'), TopicNarrow(stream.streamId, '(no topic)')),
-          (mkUrlString('lunch'),        TopicNarrow(stream.streamId, 'lunch')),
+          (mkUrlString('(no.20topic)'), eg.topicNarrow(stream.streamId, '(no topic)')),
+          (mkUrlString('lunch'),        eg.topicNarrow(stream.streamId, 'lunch')),
         ];
         testExpectedNarrows(testCases, streams: [stream]);
       });
@@ -529,12 +529,12 @@ void main() {
           return '#narrow/stream/${stream.name}/topic/$operand';
         }
         final testCases = [
-          (mkUrlString('(no.20topic)'), TopicNarrow(stream.streamId, '(no topic)')),
-          (mkUrlString('google.2Ecom'), TopicNarrow(stream.streamId, 'google.com')),
+          (mkUrlString('(no.20topic)'), eg.topicNarrow(stream.streamId, '(no topic)')),
+          (mkUrlString('google.2Ecom'), eg.topicNarrow(stream.streamId, 'google.com')),
           (mkUrlString('google.com'),   null),
-          (mkUrlString('topic.20name'), TopicNarrow(stream.streamId, 'topic name')),
-          (mkUrlString('stream'),       TopicNarrow(stream.streamId, 'stream')),
-          (mkUrlString('topic'),        TopicNarrow(stream.streamId, 'topic')),
+          (mkUrlString('topic.20name'), eg.topicNarrow(stream.streamId, 'topic name')),
+          (mkUrlString('stream'),       eg.topicNarrow(stream.streamId, 'stream')),
+          (mkUrlString('topic'),        eg.topicNarrow(stream.streamId, 'topic')),
         ];
         testExpectedNarrows(testCases, streams: [stream]);
       });
diff --git a/test/model/message_list_test.dart b/test/model/message_list_test.dart
index e92b2489b3..6a1d103c84 100644
--- a/test/model/message_list_test.dart
+++ b/test/model/message_list_test.dart
@@ -440,7 +440,7 @@ void main() {
     });
 
     test('in TopicNarrow, stay visible', () async {
-      await prepare(narrow: TopicNarrow(stream.streamId, topic));
+      await prepare(narrow: eg.topicNarrow(stream.streamId, topic));
       await prepareMutes();
       await prepareMessages(foundOldest: true, messages: [
         eg.streamMessage(id: 1, stream: stream, topic: topic),
@@ -720,7 +720,7 @@ void main() {
 
         await store.handleEvent(eg.updateMessageEventMoveFrom(
           origMessages: movedMessages,
-          newTopic: 'new',
+          newTopicStr: 'new',
         ));
         checkHasMessages(initialMessages + movedMessages);
         checkNotified(count: 2);
@@ -738,7 +738,7 @@ void main() {
 
         await store.handleEvent(eg.updateMessageEventMoveFrom(
           origMessages: movedMessages,
-          newTopic: 'new',
+          newTopicStr: 'new',
         ));
         checkHasMessages(initialMessages + movedMessages);
         checkNotified(count: 2);
@@ -752,7 +752,7 @@ void main() {
           messages: initialMessages + movedMessages,
         ).toJson());
         await store.handleEvent(eg.updateMessageEventMoveTo(
-          origTopic: 'orig topic',
+          origTopicStr: 'orig topic',
           origStreamId: otherStream.streamId,
           newMessages: movedMessages,
         ));
@@ -770,7 +770,7 @@ void main() {
 
         await store.handleEvent(eg.updateMessageEventMoveFrom(
           origMessages: movedMessages,
-          newTopic: 'new',
+          newTopicStr: 'new',
           newStreamId: otherStream.streamId,
         ));
         checkHasMessages(initialMessages);
@@ -793,7 +793,7 @@ void main() {
 
         await store.handleEvent(eg.updateMessageEventMoveFrom(
           origMessages: otherChannelMovedMessages,
-          newTopic: 'new',
+          newTopicStr: 'new',
         ));
         checkHasMessages(initialMessages);
         checkNotNotified();
@@ -807,7 +807,7 @@ void main() {
         ).toJson());
         await store.handleEvent(eg.updateMessageEventMoveFrom(
           origMessages: movedMessages,
-          newTopic: 'new',
+          newTopicStr: 'new',
           newStreamId: otherStream.streamId,
           propagateMode: propagateMode,
         ));
@@ -832,7 +832,7 @@ void main() {
     });
 
     group('in topic narrow', () {
-      final narrow = TopicNarrow(stream.streamId, 'topic');
+      final narrow = eg.topicNarrow(stream.streamId, 'topic');
       final initialMessages = List.generate(5, (i) => eg.streamMessage(stream: stream, topic: 'topic'));
       final movedMessages = List.generate(5, (i) => eg.streamMessage(stream: stream, topic: 'topic'));
       final otherTopicMovedMessages = List.generate(5, (i) => eg.streamMessage(stream: stream, topic: 'other topic'));
@@ -855,7 +855,7 @@ void main() {
             ).toJson());
             await store.handleEvent(eg.updateMessageEventMoveTo(
               origStreamId: origStreamId,
-              origTopic: origTopic,
+              origTopicStr: origTopic,
               newMessages: movedMessages,
             ));
             check(model).fetched.isFalse();
@@ -883,7 +883,7 @@ void main() {
             await store.handleEvent(eg.updateMessageEventMoveFrom(
               origMessages: movedMessages,
               newStreamId: newStreamId,
-              newTopic: newTopic,
+              newTopicStr: newTopic,
             ));
             checkHasMessages(initialMessages);
             checkNotifiedOnce();
@@ -896,7 +896,7 @@ void main() {
           await prepareNarrow(narrow, initialMessages);
 
           await store.handleEvent(eg.updateMessageEventMoveTo(
-            origTopic: 'other',
+            origTopicStr: 'other',
             newMessages: otherTopicMovedMessages,
           ));
           check(model).fetched.isTrue();
@@ -925,7 +925,7 @@ void main() {
         ).toJson());
         await store.handleEvent(eg.updateMessageEventMoveFrom(
           origMessages: movedMessages,
-          newTopic: 'new',
+          newTopicStr: 'new',
           newStreamId: otherStream.streamId,
           propagateMode: propagateMode,
         ));
@@ -937,21 +937,21 @@ void main() {
         handleMoveEvent(PropagateMode.changeOne);
         checkNotNotified();
         checkHasMessages(initialMessages);
-        check(model).narrow.equals(TopicNarrow(stream.streamId, 'topic'));
+        check(model).narrow.equals(eg.topicNarrow(stream.streamId, 'topic'));
       });
 
       test('follow to the new narrow when propagateMode = changeLater', () {
         handleMoveEvent(PropagateMode.changeLater);
         checkNotifiedOnce();
         checkHasMessages(movedMessages);
-        check(model).narrow.equals(TopicNarrow(otherStream.streamId, 'new'));
+        check(model).narrow.equals(eg.topicNarrow(otherStream.streamId, 'new'));
       });
 
       test('follow to the new narrow when propagateMode = changeAll', () {
         handleMoveEvent(PropagateMode.changeAll);
         checkNotifiedOnce();
         checkHasMessages(movedMessages);
-        check(model).narrow.equals(TopicNarrow(otherStream.streamId, 'new'));
+        check(model).narrow.equals(eg.topicNarrow(otherStream.streamId, 'new'));
       });
 
       test('handle move event before initial fetch', () => awaitFakeAsync((async) async {
@@ -969,11 +969,11 @@ void main() {
         check(model).fetched.isFalse();
         checkHasMessages([]);
         await store.handleEvent(eg.updateMessageEventMoveTo(
-          origTopic: 'topic',
+          origTopicStr: 'topic',
           newMessages: [followedMessage],
           propagateMode: PropagateMode.changeAll,
         ));
-        check(model).narrow.equals(TopicNarrow(stream.streamId, 'new'));
+        check(model).narrow.equals(eg.topicNarrow(stream.streamId, 'new'));
 
         async.elapse(const Duration(seconds: 2));
         checkHasMessages([followedMessage]);
@@ -1255,7 +1255,7 @@ void main() {
 
       int notifiedCount2 = 0;
       final model2 = MessageListView.init(store: store,
-          narrow: TopicNarrow(stream.streamId, 'hello'))
+          narrow: eg.topicNarrow(stream.streamId, 'hello'))
         ..addListener(() => notifiedCount2++);
 
       for (final m in [model1, model2]) {
@@ -1481,7 +1481,7 @@ void main() {
 
     test('in TopicNarrow', () async {
       final stream = eg.stream();
-      await prepare(narrow: TopicNarrow(stream.streamId, 'A'));
+      await prepare(narrow: eg.topicNarrow(stream.streamId, 'A'));
       await store.addStream(stream);
       await store.addSubscription(eg.subscription(stream, isMuted: true));
       await store.addUserTopic(stream, 'A', UserTopicVisibilityPolicy.muted);
diff --git a/test/model/message_test.dart b/test/model/message_test.dart
index c1fad15ac7..43f17be61a 100644
--- a/test/model/message_test.dart
+++ b/test/model/message_test.dart
@@ -320,7 +320,7 @@ void main() {
         final originalDisplayRecipient = origMessages[0].displayRecipient!;
         await store.handleEvent(eg.updateMessageEventMoveFrom(
           origMessages: origMessages,
-          newTopic:  'new topic'));
+          newTopicStr: 'new topic'));
         checkNotified(count: 2);
         check(store).messages.values.every(((message) =>
           message.isA<StreamMessage>()
@@ -332,7 +332,7 @@ void main() {
         await prepareOrigMessages(origTopic: 'new topic');
         await store.handleEvent(eg.updateMessageEventMoveFrom(
           origMessages: origMessages,
-          newTopic:  '✔ new topic'));
+          newTopicStr: '✔ new topic'));
         checkNotified(count: 2);
         check(store).messages.values.every(((message) => message.editState.equals(MessageEditState.none)));
       });
@@ -341,7 +341,7 @@ void main() {
         await prepareOrigMessages(origTopic: '✔ new topic');
         await store.handleEvent(eg.updateMessageEventMoveFrom(
           origMessages: origMessages,
-          newTopic:  'new topic'));
+          newTopicStr: 'new topic'));
         checkNotified(count: 2);
         check(store).messages.values.every(((message) => message.editState.equals(MessageEditState.none)));
       });
@@ -350,7 +350,7 @@ void main() {
         await prepareOrigMessages(origTopic: 'new topic');
         await store.handleEvent(eg.updateMessageEventMoveFrom(
           origMessages: origMessages,
-          newTopic:  '✔ new topic 2'));
+          newTopicStr: '✔ new topic 2'));
         checkNotified(count: 2);
         check(store).messages.values.every(((message) => message.editState.equals(MessageEditState.moved)));
       });
@@ -359,7 +359,7 @@ void main() {
         await prepareOrigMessages(origTopic: '✔ new topic');
         await store.handleEvent(eg.updateMessageEventMoveFrom(
           origMessages: origMessages,
-          newTopic:  'new topic 2'));
+          newTopicStr: 'new topic 2'));
         checkNotified(count: 2);
         check(store).messages.values.every(((message) => message.editState.equals(MessageEditState.moved)));
       });
diff --git a/test/model/narrow_checks.dart b/test/model/narrow_checks.dart
index 241547d782..ce65de854d 100644
--- a/test/model/narrow_checks.dart
+++ b/test/model/narrow_checks.dart
@@ -1,5 +1,6 @@
 
 import 'package:checks/checks.dart';
+import 'package:zulip/api/model/model.dart';
 import 'package:zulip/api/model/narrow.dart';
 import 'package:zulip/model/narrow.dart';
 
@@ -14,5 +15,5 @@ extension DmNarrowChecks on Subject<DmNarrow> {
 
 extension TopicNarrowChecks on Subject<TopicNarrow> {
   Subject<int> get streamId => has((x) => x.streamId, 'streamId');
-  Subject<String> get topic => has((x) => x.topic, 'topic');
+  Subject<TopicName> get topic => has((x) => x.topic, 'topic');
 }
diff --git a/test/model/recent_senders_test.dart b/test/model/recent_senders_test.dart
index 2da516e11c..602362cbcc 100644
--- a/test/model/recent_senders_test.dart
+++ b/test/model/recent_senders_test.dart
@@ -7,7 +7,7 @@ import '../example_data.dart' as eg;
 /// [messages] should be sorted by [id] ascending.
 void checkMatchesMessages(RecentSenders model, List<Message> messages) {
   final Map<int, Map<int, Set<int>>> messagesByUserInStream = {};
-  final Map<int, Map<String, Map<int, Set<int>>>> messagesByUserInTopic = {};
+  final Map<int, Map<TopicName, Map<int, Set<int>>>> messagesByUserInTopic = {};
   for (final message in messages) {
     if (message is! StreamMessage) {
       throw UnsupportedError('Message of type ${message.runtimeType} is not expected.');
@@ -199,15 +199,15 @@ void main() {
     model.handleMessages(messages);
 
     check(model.latestMessageIdOfSenderInTopic(streamId: 1,
-      topic: 'a', senderId: 10)).equals(300);
+      topic: eg.t('a'), senderId: 10)).equals(300);
     // No message of user 20 in topic "a".
     check(model.latestMessageIdOfSenderInTopic(streamId: 1,
-      topic: 'a', senderId: 20)).equals(null);
+      topic: eg.t('a'), senderId: 20)).equals(null);
     // No message in topic "b" at all.
     check(model.latestMessageIdOfSenderInTopic(streamId: 1,
-      topic: 'b', senderId: 10)).equals(null);
+      topic: eg.t('b'), senderId: 10)).equals(null);
     // No message in stream 2 at all.
     check(model.latestMessageIdOfSenderInTopic(streamId: 2,
-      topic: 'a', senderId: 10)).equals(null);
+      topic: eg.t('a'), senderId: 10)).equals(null);
   });
 }
diff --git a/test/model/store_checks.dart b/test/model/store_checks.dart
index 3495aa0359..f2ef63cd4b 100644
--- a/test/model/store_checks.dart
+++ b/test/model/store_checks.dart
@@ -31,6 +31,7 @@ extension PerAccountStoreChecks on Subject<PerAccountStore> {
   Subject<bool> get isLoading => has((x) => x.isLoading, 'isLoading');
   Subject<Uri> get realmUrl => has((x) => x.realmUrl, 'realmUrl');
   Subject<String> get zulipVersion => has((x) => x.zulipVersion, 'zulipVersion');
+  Subject<bool> get realmMandatoryTopics => has((x) => x.realmMandatoryTopics, 'realmMandatoryTopics');
   Subject<int> get maxFileUploadSizeMib => has((x) => x.maxFileUploadSizeMib, 'maxFileUploadSizeMib');
   Subject<Map<String, RealmDefaultExternalAccount>> get realmDefaultExternalAccounts => has((x) => x.realmDefaultExternalAccounts, 'realmDefaultExternalAccounts');
   Subject<List<CustomProfileField>> get customProfileFields => has((x) => x.customProfileFields, 'customProfileFields');
diff --git a/test/model/store_test.dart b/test/model/store_test.dart
index 10e8698360..c8c6b4c266 100644
--- a/test/model/store_test.dart
+++ b/test/model/store_test.dart
@@ -386,7 +386,7 @@ void main() {
       final stream = eg.stream();
       connection.prepare(json: SendMessageResult(id: 12345).toJson());
       await store.sendMessage(
-        destination: StreamDestination(stream.streamId, 'world'),
+        destination: StreamDestination(stream.streamId, eg.t('world')),
         content: 'hello');
       check(connection.takeRequests()).single.isA<http.Request>()
         ..method.equals('POST')
diff --git a/test/model/test_store.dart b/test/model/test_store.dart
index 2322e78d7a..b6887cbed7 100644
--- a/test/model/test_store.dart
+++ b/test/model/test_store.dart
@@ -85,6 +85,9 @@ class TestGlobalStore extends GlobalStore {
   /// [PerAccountStore] when [perAccount] is subsequently called for this
   /// account, in particular when a [PerAccountStoreWidget] is mounted.
   Future<void> add(Account account, InitialSnapshot initialSnapshot) async {
+    assert(initialSnapshot.zulipVersion == account.zulipVersion);
+    assert(initialSnapshot.zulipMergeBase == account.zulipMergeBase);
+    assert(initialSnapshot.zulipFeatureLevel == account.zulipFeatureLevel);
     await insertAccount(account.toCompanion(false));
     assert(!_initialSnapshots.containsKey(account.id));
     _initialSnapshots[account.id] = initialSnapshot;
diff --git a/test/model/typing_status_test.dart b/test/model/typing_status_test.dart
index 45348afb01..4061301366 100644
--- a/test/model/typing_status_test.dart
+++ b/test/model/typing_status_test.dart
@@ -35,7 +35,7 @@ void checkSetTypingStatusRequests(
           'type': 'channel',
           'op': op.toJson(),
           'stream_id': narrow.streamId.toString(),
-          'topic': narrow.topic}),
+          'topic': narrow.topic.apiName}),
         DmNarrow() => conditionTypingRequest({
           'type': 'direct',
           'op': op.toJson(),
@@ -94,7 +94,7 @@ void main() {
   }
 
   final stream = eg.stream();
-  final topicNarrow = TopicNarrow(stream.streamId, 'foo');
+  final topicNarrow = eg.topicNarrow(stream.streamId, 'foo');
 
   final dmNarrow = DmNarrow.withUser(eg.otherUser.userId, selfUserId: eg.selfUser.userId);
   final groupNarrow = DmNarrow.withOtherUsers(
@@ -272,7 +272,7 @@ void main() {
       final channel = eg.stream();
       await store.addStream(channel);
       await store.addSubscription(eg.subscription(channel));
-      narrow = TopicNarrow(channel.streamId, 'topic');
+      narrow = eg.topicNarrow(channel.streamId, 'topic');
     }
 
     /// Prepares store and triggers a "typing started" notice.
diff --git a/test/model/unreads_checks.dart b/test/model/unreads_checks.dart
index 836e497b2b..ac4d64846a 100644
--- a/test/model/unreads_checks.dart
+++ b/test/model/unreads_checks.dart
@@ -1,10 +1,11 @@
 import 'package:checks/checks.dart';
 import 'package:collection/collection.dart';
+import 'package:zulip/api/model/model.dart';
 import 'package:zulip/model/narrow.dart';
 import 'package:zulip/model/unreads.dart';
 
 extension UnreadsChecks on Subject<Unreads> {
-  Subject<Map<int, Map<String, QueueList<int>>>> get streams => has((u) => u.streams, 'streams');
+  Subject<Map<int, Map<TopicName, QueueList<int>>>> get streams => has((u) => u.streams, 'streams');
   Subject<Map<DmNarrow, QueueList<int>>> get dms => has((u) => u.dms, 'dms');
   Subject<Set<int>> get mentions => has((u) => u.mentions, 'mentions');
   Subject<bool> get oldUnreadsMissing => has((u) => u.oldUnreadsMissing, 'oldUnreadsMissing');
diff --git a/test/model/unreads_test.dart b/test/model/unreads_test.dart
index f5eab5a845..40e074dcaa 100644
--- a/test/model/unreads_test.dart
+++ b/test/model/unreads_test.dart
@@ -58,7 +58,7 @@ void main() {
     assert(Set.of(messages.map((m) => m.id)).length == messages.length,
       'checkMatchesMessages: duplicate messages in test input');
 
-    final Map<int, Map<String, QueueList<int>>> expectedStreams = {};
+    final Map<int, Map<TopicName, QueueList<int>>> expectedStreams = {};
     final Map<DmNarrow, QueueList<int>> expectedDms = {};
     final Set<int> expectedMentions = {};
     for (final message in messages) {
@@ -114,10 +114,10 @@ void main() {
       prepare(initial: UnreadMessagesSnapshot(
         count: 0,
         channels: [
-          UnreadChannelSnapshot(streamId: stream1.streamId, topic: 'a', unreadMessageIds: [1, 2]),
-          UnreadChannelSnapshot(streamId: stream1.streamId, topic: 'b', unreadMessageIds: [3, 4]),
-          UnreadChannelSnapshot(streamId: stream2.streamId, topic: 'b', unreadMessageIds: [5, 6]),
-          UnreadChannelSnapshot(streamId: stream2.streamId, topic: 'c', unreadMessageIds: [7, 8]),
+          eg.unreadChannelMsgs(streamId: stream1.streamId, topic: 'a', unreadMessageIds: [1, 2]),
+          eg.unreadChannelMsgs(streamId: stream1.streamId, topic: 'b', unreadMessageIds: [3, 4]),
+          eg.unreadChannelMsgs(streamId: stream2.streamId, topic: 'b', unreadMessageIds: [5, 6]),
+          eg.unreadChannelMsgs(streamId: stream2.streamId, topic: 'c', unreadMessageIds: [7, 8]),
         ],
         dms: [
           UnreadDmSnapshot(otherUserId: 1, unreadMessageIds: [9, 10]),
@@ -204,7 +204,7 @@ void main() {
       prepare();
       fillWithMessages(List.generate(7, (i) => eg.streamMessage(
         stream: stream, topic: 'a', flags: [])));
-      check(model.countInTopicNarrow(stream.streamId, 'a')).equals(7);
+      check(model.countInTopicNarrow(stream.streamId, eg.t('a'))).equals(7);
     });
 
     test('countInDmNarrow', () {
@@ -538,7 +538,7 @@ void main() {
         messageIds: [11, 12],
         messageType: MessageType.stream,
         streamId: stream1.streamId,
-        topic: 'a',
+        topic: eg.t('a'),
       ));
       checkNotifiedOnce();
       checkMatchesMessages(expectedRemainingMessages..removeAll([message11, message12]));
@@ -547,7 +547,7 @@ void main() {
         messageIds: [13, 14],
         messageType: MessageType.stream,
         streamId: stream2.streamId,
-        topic: 'b',
+        topic: eg.t('b'),
       ));
       checkNotifiedOnce();
       checkMatchesMessages(expectedRemainingMessages..removeAll([message13, message14]));
@@ -1029,7 +1029,7 @@ void main() {
                 type: MessageType.stream,
                 mentioned: false,
                 streamId: stream.streamId,
-                topic: topic,
+                topic: eg.t(topic),
                 userIds: null,
               ),
               // message 2 and 3 have their details missing
diff --git a/test/notifications/display_test.dart b/test/notifications/display_test.dart
index cb49a5f8a8..b1c56b55b1 100644
--- a/test/notifications/display_test.dart
+++ b/test/notifications/display_test.dart
@@ -540,21 +540,47 @@ void main() {
         messageStyleMessages: [data1],
         expectedIsGroupConversation: true,
         expectedTitle: '#${stream.name} > $topicA',
-        expectedTagComponent: 'stream:${stream.streamId}:$topicA');
+        expectedTagComponent: 'stream:${stream.streamId}:${topicA.toLowerCase()}');
 
       receiveFcmMessage(async, data2);
       checkNotification(data2,
         messageStyleMessages: [data2],
         expectedIsGroupConversation: true,
         expectedTitle: '#${stream.name} > $topicB',
-        expectedTagComponent: 'stream:${stream.streamId}:$topicB');
+        expectedTagComponent: 'stream:${stream.streamId}:${topicB.toLowerCase()}');
 
       receiveFcmMessage(async, data3);
       checkNotification(data3,
         messageStyleMessages: [data1, data3],
         expectedIsGroupConversation: true,
         expectedTitle: '#${stream.name} > $topicA',
-        expectedTagComponent: 'stream:${stream.streamId}:$topicA');
+        expectedTagComponent: 'stream:${stream.streamId}:${topicA.toLowerCase()}');
+    })));
+
+    test('stream message: topic changes only case', () => runWithHttpClient(() => awaitFakeAsync((async) async {
+      await init();
+      final stream = eg.stream();
+      const topic1 = 'A ToPic';
+      const topic2 = 'a TOpic';
+      final message1 = eg.streamMessage(topic: topic1, stream: stream);
+      final data1 = messageFcmMessage(message1, streamName: stream.name);
+      final message2 = eg.streamMessage(topic: topic2, stream: stream);
+      final data2 = messageFcmMessage(message2, streamName: stream.name);
+
+      receiveFcmMessage(async, data1);
+      checkNotification(data1,
+        messageStyleMessages: [data1],
+        expectedIsGroupConversation: true,
+        expectedTitle: '#${stream.name} > $topic1',
+        expectedTagComponent: 'stream:${stream.streamId}:a topic');
+
+      receiveFcmMessage(async, data2);
+      checkNotification(data2,
+        messageStyleMessages: [data1, data2],
+        expectedIsGroupConversation: true,
+        // Title updates with latest casing of topic.
+        expectedTitle: '#${stream.name} > $topic2',
+        expectedTagComponent: 'stream:${stream.streamId}:a topic');
     })));
 
     test('stream message: conversation stays same when stream is renamed', () => runWithHttpClient(() => awaitFakeAsync((async) async {
@@ -781,6 +807,7 @@ void main() {
       final data2 = messageFcmMessage(message2, streamName: stream.name);
       final message3 = eg.streamMessage(stream: stream, topic: topicA);
       final data3 = messageFcmMessage(message3, streamName: stream.name);
+      final conversationKey = 'stream:${stream.streamId}:${topicA.toLowerCase()}';
       final expectedGroupKey = '${data1.realmUrl}|${data1.userId}';
 
       check(testBinding.androidNotificationHost.activeNotifications).isEmpty();
@@ -789,14 +816,14 @@ void main() {
       receiveFcmMessage(async, data2);
       receiveFcmMessage(async, data3);
       check(testBinding.androidNotificationHost.activeNotifications).deepEquals(<Condition<Object?>>[
-        conditionActiveNotif(data3, 'stream:${stream.streamId}:$topicA'),
+        conditionActiveNotif(data3, conversationKey),
         conditionSummaryActiveNotif(expectedGroupKey),
       ]);
 
       // A RemoveFcmMessage for the first two messages; the notification stays.
       receiveFcmMessage(async, removeFcmMessage([message1, message2]));
       check(testBinding.androidNotificationHost.activeNotifications).deepEquals(<Condition<Object?>>[
-        conditionActiveNotif(data3, 'stream:${stream.streamId}:$topicA'),
+        conditionActiveNotif(data3, conversationKey),
         conditionSummaryActiveNotif(expectedGroupKey),
       ]);
 
@@ -808,13 +835,17 @@ void main() {
     test('remove: clears summary notification only if all conversation notifications are cleared', () => runWithHttpClient(() => awaitFakeAsync((async) async {
       await init();
       final stream = eg.stream();
+
       const topicA = 'Topic A';
       final message1 = eg.streamMessage(stream: stream, topic: topicA);
       final data1 = messageFcmMessage(message1, streamName: stream.name);
+      final conversationKey1 = 'stream:${stream.streamId}:${topicA.toLowerCase()}';
+      final expectedGroupKey = '${data1.realmUrl}|${data1.userId}';
+
       const topicB = 'Topic B';
       final message2 = eg.streamMessage(stream: stream, topic: topicB);
       final data2 = messageFcmMessage(message2, streamName: stream.name);
-      final expectedGroupKey = '${data1.realmUrl}|${data1.userId}';
+      final conversationKey2 = 'stream:${stream.streamId}:${topicB.toLowerCase()}';
 
       check(testBinding.androidNotificationHost.activeNotifications).isEmpty();
 
@@ -822,16 +853,16 @@ void main() {
       receiveFcmMessage(async, data1);
       receiveFcmMessage(async, data2);
       check(testBinding.androidNotificationHost.activeNotifications).deepEquals(<Condition<Object?>>[
-        conditionActiveNotif(data1, 'stream:${stream.streamId}:$topicA'),
+        conditionActiveNotif(data1, conversationKey1),
         conditionSummaryActiveNotif(expectedGroupKey),
-        conditionActiveNotif(data2, 'stream:${stream.streamId}:$topicB'),
+        conditionActiveNotif(data2, conversationKey2),
       ]);
 
       // A RemoveFcmMessage for first conversation; only clears the first conversation notif.
       receiveFcmMessage(async, removeFcmMessage([message1]));
       check(testBinding.androidNotificationHost.activeNotifications).deepEquals(<Condition<Object?>>[
         conditionSummaryActiveNotif(expectedGroupKey),
-        conditionActiveNotif(data2, 'stream:${stream.streamId}:$topicB'),
+        conditionActiveNotif(data2, conversationKey2),
       ]);
 
       // Then a RemoveFcmMessage for the only remaining conversation;
@@ -844,6 +875,7 @@ void main() {
       await init();
       final stream = eg.stream();
       const topic = 'Some Topic';
+      final conversationKey = 'stream:${stream.streamId}:some topic';
 
       final account1 = eg.account(
         realmUrl: Uri.parse('https://1.chat.example'),
@@ -868,15 +900,15 @@ void main() {
       receiveFcmMessage(async, data1);
       receiveFcmMessage(async, data2);
       check(testBinding.androidNotificationHost.activeNotifications).deepEquals(<Condition<Object?>>[
-        conditionActiveNotif(data1, 'stream:${stream.streamId}:$topic'),
+        conditionActiveNotif(data1, conversationKey),
         conditionSummaryActiveNotif(groupKey1),
-        conditionActiveNotif(data2, 'stream:${stream.streamId}:$topic'),
+        conditionActiveNotif(data2, conversationKey),
         conditionSummaryActiveNotif(groupKey2),
       ]);
 
       receiveFcmMessage(async, removeFcmMessage([message1], account: account1));
       check(testBinding.androidNotificationHost.activeNotifications).deepEquals(<Condition<Object?>>[
-        conditionActiveNotif(data2, 'stream:${stream.streamId}:$topic'),
+        conditionActiveNotif(data2, conversationKey),
         conditionSummaryActiveNotif(groupKey2),
       ]);
 
@@ -889,6 +921,7 @@ void main() {
       final realmUrl = eg.realmUrl;
       final stream = eg.stream();
       const topic = 'Some Topic';
+      final conversationKey = 'stream:${stream.streamId}:some topic';
 
       final account1 = eg.account(id: 1001, user: eg.user(userId: 1001), realmUrl: realmUrl);
       final message1 = eg.streamMessage(id: 1000, stream: stream, topic: topic);
@@ -907,15 +940,15 @@ void main() {
       receiveFcmMessage(async, data1);
       receiveFcmMessage(async, data2);
       check(testBinding.androidNotificationHost.activeNotifications).deepEquals(<Condition<Object?>>[
-        conditionActiveNotif(data1, 'stream:${stream.streamId}:$topic'),
+        conditionActiveNotif(data1, conversationKey),
         conditionSummaryActiveNotif(groupKey1),
-        conditionActiveNotif(data2, 'stream:${stream.streamId}:$topic'),
+        conditionActiveNotif(data2, conversationKey),
         conditionSummaryActiveNotif(groupKey2),
       ]);
 
       receiveFcmMessage(async, removeFcmMessage([message1], account: account1));
       check(testBinding.androidNotificationHost.activeNotifications).deepEquals(<Condition<Object?>>[
-        conditionActiveNotif(data2, 'stream:${stream.streamId}:$topic'),
+        conditionActiveNotif(data2, conversationKey),
         conditionSummaryActiveNotif(groupKey2),
       ]);
 
@@ -927,11 +960,12 @@ void main() {
   group('NotificationDisplayManager open', () {
     late List<Route<void>> pushedRoutes;
 
-    void takeStartingRoutes({bool withAccount = true}) {
+    void takeStartingRoutes({Account? account, bool withAccount = true}) {
+      account ??= eg.selfAccount;
       final expected = <Condition<Object?>>[
         if (withAccount)
           (it) => it.isA<MaterialAccountWidgetRoute>()
-            ..accountId.equals(eg.selfAccount.id)
+            ..accountId.equals(account!.id)
             ..page.isA<HomePage>()
         else
           (it) => it.isA<WidgetRoute>().page.isA<ChooseAccountPage>(),
@@ -1003,6 +1037,21 @@ void main() {
         eg.dmMessage(from: eg.otherUser, to: [eg.selfUser]));
     });
 
+    testWidgets('account queried by realmUrl origin component', (tester) async {
+      addTearDown(testBinding.reset);
+      await testBinding.globalStore.add(
+        eg.selfAccount.copyWith(realmUrl: Uri.parse('http://chat.example')),
+        eg.initialSnapshot());
+      await prepare(tester);
+
+      await checkOpenNotification(tester,
+        eg.selfAccount.copyWith(realmUrl: Uri.parse('http://chat.example/')),
+        eg.streamMessage());
+      await checkOpenNotification(tester,
+        eg.selfAccount.copyWith(realmUrl: Uri.parse('http://chat.example')),
+        eg.streamMessage());
+    });
+
     testWidgets('no accounts', (tester) async {
       await prepare(tester, withAccount: false);
       await openNotification(tester, eg.selfAccount, eg.streamMessage());
@@ -1079,11 +1128,12 @@ void main() {
         realmUrl: data.realmUrl,
         userId: data.userId,
         narrow: switch (data.recipient) {
-        FcmMessageChannelRecipient(:var streamId, :var topic) =>
-          TopicNarrow(streamId, topic),
-        FcmMessageDmRecipient(:var allRecipientIds) =>
-          DmNarrow(allRecipientIds: allRecipientIds, selfUserId: data.userId),
-      }).buildUrl();
+          FcmMessageChannelRecipient(:var streamId, :var topic) =>
+            TopicNarrow(streamId, topic),
+          FcmMessageDmRecipient(:var allRecipientIds) =>
+            DmNarrow(allRecipientIds: allRecipientIds, selfUserId: data.userId),
+        }).buildUrl();
+      addTearDown(tester.binding.platformDispatcher.clearDefaultRouteNameTestValue);
       tester.binding.platformDispatcher.defaultRouteNameTestValue = intentDataUrl.toString();
 
       // Now start the app.
@@ -1096,6 +1146,36 @@ void main() {
       takeStartingRoutes();
       matchesNavigation(check(pushedRoutes).single, account, message);
     });
+
+    testWidgets('uses associated account as initial account; if initial route', (tester) async {
+      addTearDown(testBinding.reset);
+
+      final accountA = eg.selfAccount;
+      final accountB = eg.otherAccount;
+      final message = eg.streamMessage();
+      final data = messageFcmMessage(message, account: accountB);
+      await testBinding.globalStore.add(accountA, eg.initialSnapshot());
+      await testBinding.globalStore.add(accountB, eg.initialSnapshot());
+
+      final intentDataUrl = NotificationOpenPayload(
+        realmUrl: data.realmUrl,
+        userId: data.userId,
+        narrow: switch (data.recipient) {
+          FcmMessageChannelRecipient(:var streamId, :var topic) =>
+            TopicNarrow(streamId, topic),
+          FcmMessageDmRecipient(:var allRecipientIds) =>
+            DmNarrow(allRecipientIds: allRecipientIds, selfUserId: data.userId),
+        }).buildUrl();
+      addTearDown(tester.binding.platformDispatcher.clearDefaultRouteNameTestValue);
+      tester.binding.platformDispatcher.defaultRouteNameTestValue = intentDataUrl.toString();
+
+      await prepare(tester, early: true);
+      check(pushedRoutes).isEmpty(); // GlobalStore hasn't loaded yet
+
+      await tester.pump();
+      takeStartingRoutes(account: accountB);
+      matchesNavigation(check(pushedRoutes).single, accountB, message);
+    });
   });
 
   group('NotificationOpenPayload', () {
@@ -1116,7 +1196,7 @@ void main() {
       payload = NotificationOpenPayload(
         realmUrl: Uri.parse('http://chat.example'),
         userId: 1001,
-        narrow: const TopicNarrow(1, 'topic A'),
+        narrow: eg.topicNarrow(1, 'topic A'),
       );
       url = payload.buildUrl();
       check(NotificationOpenPayload.parseUrl(url))
@@ -1146,7 +1226,7 @@ void main() {
       final url = NotificationOpenPayload(
         realmUrl: Uri.parse('http://chat.example'),
         userId: 1001,
-        narrow: const TopicNarrow(1, 'topic A'),
+        narrow: eg.topicNarrow(1, 'topic A'),
       ).buildUrl();
       check(url)
         ..scheme.equals('zulip')
@@ -1194,7 +1274,7 @@ void main() {
         ..userId.equals(1001)
         ..narrow.which((it) => it.isA<TopicNarrow>()
           ..streamId.equals(1)
-          ..topic.equals('topic A'));
+          ..topic.equals(eg.t('topic A')));
     });
 
     test('parse: fails when missing any expected query parameters', () {
diff --git a/test/widgets/action_sheet_test.dart b/test/widgets/action_sheet_test.dart
index cf19bc3e9f..7da94cfd36 100644
--- a/test/widgets/action_sheet_test.dart
+++ b/test/widgets/action_sheet_test.dart
@@ -1,12 +1,14 @@
 import 'dart:convert';
 
 import 'package:checks/checks.dart';
+import 'package:collection/collection.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_checks/flutter_checks.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:http/http.dart' as http;
 import 'package:zulip/api/model/events.dart';
+import 'package:zulip/api/model/initial_snapshot.dart';
 import 'package:zulip/api/model/model.dart';
 import 'package:zulip/api/route/channels.dart';
 import 'package:zulip/api/route/messages.dart';
@@ -106,27 +108,58 @@ void main() {
     connection.prepare(httpStatus: 400, json: fakeResponseJson);
   }
 
-  group('showTopicActionSheet', () {
-    final channel = eg.stream();
-    const topic = 'my topic';
-    final message = eg.streamMessage(
-      stream: channel, topic: topic, sender: eg.otherUser);
+  group('topic action sheet', () {
+    final someChannel = eg.stream();
+    const someTopic = 'my topic';
+    final someMessage = eg.streamMessage(
+      stream: someChannel, topic: someTopic, sender: eg.otherUser);
+
+    Future<void> prepare({
+      ZulipStream? channel,
+      String topic = someTopic,
+      bool isChannelSubscribed = true,
+      bool? isChannelMuted,
+      UserTopicVisibilityPolicy? visibilityPolicy,
+      UnreadMessagesSnapshot? unreadMsgs,
+      int? zulipFeatureLevel,
+    }) async {
+      final effectiveChannel = channel ?? someChannel;
+      assert(isChannelSubscribed || isChannelMuted == null);
 
-    Future<void> prepare() async {
       addTearDown(testBinding.reset);
 
-      await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot(
+      final account = eg.selfAccount.copyWith(zulipFeatureLevel: zulipFeatureLevel);
+      await testBinding.globalStore.add(account, eg.initialSnapshot(
         realmUsers: [eg.selfUser, eg.otherUser],
-        streams: [channel],
-        subscriptions: [eg.subscription(channel)]));
+        streams: [effectiveChannel],
+        subscriptions: isChannelSubscribed
+          ? [eg.subscription(effectiveChannel, isMuted: isChannelMuted ?? false)]
+          : null,
+        userTopics: visibilityPolicy != null
+          ? [eg.userTopicItem(effectiveChannel, topic, visibilityPolicy)]
+          : null,
+        unreadMsgs: unreadMsgs,
+        zulipFeatureLevel: zulipFeatureLevel));
       store = await testBinding.globalStore.perAccount(eg.selfAccount.id);
       connection = store.connection as FakeApiConnection;
-
-      await store.addMessage(message);
     }
 
-    testWidgets('show from inbox', (tester) async {
-      await prepare();
+    Future<void> showFromInbox(WidgetTester tester, {
+      String topic = someTopic,
+    }) async {
+      final channelIdsWithUnreads = store.unreads.streams.keys;
+      final hasTopicWithUnreads = channelIdsWithUnreads.any((streamId) =>
+        store.unreads.countInTopicNarrow(streamId, TopicName(topic)) > 0);
+      if (!hasTopicWithUnreads) {
+        throw FlutterError.fromParts([
+          ErrorSummary('showFromInbox called without an unread message'),
+          ErrorHint(
+            'Before calling showFromInbox, ensure that [Unreads] '
+            'has an unread message in the relevant topic. ',
+          ),
+        ]);
+      }
+
       await tester.pumpWidget(TestZulipApp(accountId: eg.selfAccount.id,
         child: const HomePage()));
       await tester.pump();
@@ -135,271 +168,497 @@ void main() {
       await tester.longPress(find.text(topic));
       // sheet appears onscreen; default duration of bottom-sheet enter animation
       await tester.pump(const Duration(milliseconds: 250));
-      check(find.byType(BottomSheet)).findsOne();
-      check(find.text('Follow topic')).findsOne();
-    });
+    }
+
+    Future<void> showFromAppBar(WidgetTester tester, {
+      ZulipStream? channel,
+      String topic = someTopic,
+      List<StreamMessage>? messages,
+    }) async {
+      final effectiveChannel = channel ?? someChannel;
+      final effectiveMessages = messages ?? [someMessage];
+      assert(effectiveMessages.every((m) => m.topic.apiName == topic));
 
-    testWidgets('show from app bar', (tester) async {
-      await prepare();
       connection.prepare(json: eg.newestGetMessagesResult(
-        foundOldest: true, messages: [message]).toJson());
+        foundOldest: true, messages: effectiveMessages).toJson());
       await tester.pumpWidget(TestZulipApp(accountId: eg.selfAccount.id,
         child: MessageListPage(
-          initNarrow: TopicNarrow(channel.streamId, topic))));
+          initNarrow: eg.topicNarrow(effectiveChannel.streamId, topic))));
       // global store, per-account store, and message list get loaded
       await tester.pumpAndSettle();
 
-      await tester.longPress(find.byType(ZulipAppBar));
+      final topicRow = find.descendant(
+        of: find.byType(ZulipAppBar),
+        matching: find.text(topic));
+      await tester.longPress(topicRow);
       // sheet appears onscreen; default duration of bottom-sheet enter animation
       await tester.pump(const Duration(milliseconds: 250));
-      check(find.byType(BottomSheet)).findsOne();
-      check(find.text('Follow topic')).findsOne();
-    });
+    }
+
+    Future<void> showFromRecipientHeader(WidgetTester tester, {
+      StreamMessage? message,
+    }) async {
+      final effectiveMessage = message ?? someMessage;
 
-    testWidgets('show from recipient header', (tester) async {
-      await prepare();
       connection.prepare(json: eg.newestGetMessagesResult(
-        foundOldest: true, messages: [message]).toJson());
+        foundOldest: true, messages: [effectiveMessage]).toJson());
       await tester.pumpWidget(TestZulipApp(accountId: eg.selfAccount.id,
         child: const MessageListPage(initNarrow: CombinedFeedNarrow())));
       // global store, per-account store, and message list get loaded
       await tester.pumpAndSettle();
 
       await tester.longPress(find.descendant(
-        of: find.byType(RecipientHeader), matching: find.text(topic)));
+        of: find.byType(RecipientHeader),
+        matching: find.text(effectiveMessage.topic.displayName)));
       // sheet appears onscreen; default duration of bottom-sheet enter animation
       await tester.pump(const Duration(milliseconds: 250));
-      check(find.byType(BottomSheet)).findsOne();
-      check(find.text('Follow topic')).findsOne();
-    });
-  });
+    }
 
-  group('UserTopicUpdateButton', () {
-    late ZulipStream channel;
-    late String topic;
-
-    final mute =     find.text('Mute topic');
-    final unmute =   find.text('Unmute topic');
-    final follow =   find.text('Follow topic');
-    final unfollow = find.text('Unfollow topic');
-
-    /// Prepare store and bring up a topic action sheet.
-    ///
-    /// If `isChannelMuted` is `null`, the user is not subscribed to the
-    /// channel.
-    Future<void> setupToTopicActionSheet(WidgetTester tester, {
-      required bool? isChannelMuted,
-      required UserTopicVisibilityPolicy visibilityPolicy,
-      int? zulipFeatureLevel,
-    }) async {
-      addTearDown(testBinding.reset);
+    final actionSheetFinder = find.byType(BottomSheet);
+    Finder findButtonForLabel(String label) =>
+      find.descendant(of: actionSheetFinder, matching: find.text(label));
 
-      channel = eg.stream();
-      topic = 'isChannelMuted: $isChannelMuted, policy: $visibilityPolicy';
+    group('showTopicActionSheet', () {
+      void checkButtons() {
+        check(actionSheetFinder).findsOne();
 
-      final account = eg.selfAccount.copyWith(zulipFeatureLevel: zulipFeatureLevel);
-      final subscriptions = isChannelMuted == null ? <Subscription>[]
-        : [eg.subscription(channel, isMuted: isChannelMuted)];
-      await testBinding.globalStore.add(account, eg.initialSnapshot(
-        realmUsers: [eg.selfUser],
-        streams: [channel],
-        subscriptions: subscriptions,
-        userTopics: [eg.userTopicItem(channel, topic, visibilityPolicy)],
-        zulipFeatureLevel: zulipFeatureLevel));
-      store = await testBinding.globalStore.perAccount(account.id);
-      connection = store.connection as FakeApiConnection;
+        void checkButton(String label) {
+          check(findButtonForLabel(label)).findsOne();
+        }
 
-      connection.prepare(json: eg.newestGetMessagesResult(
-        foundOldest: true, messages: [
-          eg.streamMessage(stream: channel, topic: topic)]).toJson());
-      await tester.pumpWidget(TestZulipApp(accountId: account.id,
-        child: MessageListPage(
-          initNarrow: TopicNarrow(channel.streamId, topic))));
-      await tester.pumpAndSettle();
+        checkButton('Follow topic');
+        checkButton('Mark as resolved');
+      }
 
-      await tester.longPress(find.descendant(
-        of: find.byType(RecipientHeader), matching: find.text(topic)));
-      // sheet appears onscreen; default duration of bottom-sheet enter animation
-      await tester.pump(const Duration(milliseconds: 250));
-    }
+      testWidgets('show from inbox; message in Unreads but not in MessageStore', (tester) async {
+        await prepare(unreadMsgs: eg.unreadMsgs(count: 1,
+          channels: [eg.unreadChannelMsgs(
+            streamId: someChannel.streamId,
+            topic: someTopic,
+            unreadMessageIds: [someMessage.id],
+          )]));
+        await showFromInbox(tester);
+        check(store.unreads.isUnread(someMessage.id)).isNotNull().isTrue();
+        check(store.messages).not((it) => it.containsKey(someMessage.id));
+        checkButtons();
+      });
+
+      testWidgets('show from inbox; message in Unreads and in MessageStore', (tester) async {
+        await prepare();
+        await store.addMessage(someMessage);
+        await showFromInbox(tester);
+        check(store.unreads.isUnread(someMessage.id)).isNotNull().isTrue();
+        check(store.messages)[someMessage.id].isNotNull();
+        checkButtons();
+      });
 
-    void checkButtons(List<Finder> expectedButtonFinders) {
-      if (expectedButtonFinders.isEmpty) {
-        check(find.byType(BottomSheet)).findsNothing();
-        return;
+      testWidgets('show from app bar', (tester) async {
+        await prepare();
+        await showFromAppBar(tester);
+        checkButtons();
+      });
+
+      testWidgets('show from app bar: resolve/unresolve not offered when msglist empty', (tester) async {
+        await prepare();
+        await showFromAppBar(tester, messages: []);
+        check(findButtonForLabel('Mark as resolved')).findsNothing();
+        check(findButtonForLabel('Mark as unresolved')).findsNothing();
+      });
+
+      testWidgets('show from recipient header', (tester) async {
+        await prepare();
+        await showFromRecipientHeader(tester);
+        checkButtons();
+      });
+    });
+
+    group('UserTopicUpdateButton', () {
+      late String topic;
+
+      final mute =     findButtonForLabel('Mute topic');
+      final unmute =   findButtonForLabel('Unmute topic');
+      final follow =   findButtonForLabel('Follow topic');
+      final unfollow = findButtonForLabel('Unfollow topic');
+
+      /// Prepare store and bring up a topic action sheet.
+      ///
+      /// If `isChannelMuted` is `null`, the user is not subscribed to the
+      /// channel.
+      Future<void> setupToTopicActionSheet(WidgetTester tester, {
+        required bool? isChannelMuted,
+        required UserTopicVisibilityPolicy visibilityPolicy,
+        int? zulipFeatureLevel,
+      }) async {
+        addTearDown(testBinding.reset);
+
+        topic = 'isChannelMuted: $isChannelMuted, policy: $visibilityPolicy';
+        await prepare(
+          channel: someChannel,
+          topic: topic,
+          isChannelSubscribed: isChannelMuted != null, // shorthand; see dartdoc
+          isChannelMuted: isChannelMuted,
+          visibilityPolicy: visibilityPolicy,
+          zulipFeatureLevel: zulipFeatureLevel,
+        );
+
+        final message = eg.streamMessage(
+          stream: someChannel, topic: topic, sender: eg.otherUser);
+        await showFromAppBar(tester,
+          channel: someChannel, topic: topic, messages: [message]);
       }
-      check(find.byType(BottomSheet)).findsOne();
 
-      for (final buttonFinder in expectedButtonFinders) {
-        check(buttonFinder).findsOne();
+      void checkButtons(List<Finder> expectedButtonFinders) {
+        check(actionSheetFinder).findsOne();
+
+        for (final buttonFinder in expectedButtonFinders) {
+          check(buttonFinder).findsOne();
+        }
+        check(find.bySubtype<UserTopicUpdateButton>())
+          .findsExactly(expectedButtonFinders.length);
       }
-      check(find.bySubtype<UserTopicUpdateButton>())
-        .findsExactly(expectedButtonFinders.length);
-    }
 
-    void checkUpdateUserTopicRequest(UserTopicVisibilityPolicy expectedPolicy) async {
-      check(connection.lastRequest).isA<http.Request>()
-        ..url.path.equals('/api/v1/user_topics')
-        ..bodyFields.deepEquals({
-          'stream_id': '${channel.streamId}',
-          'topic': topic,
-          'visibility_policy': jsonEncode(expectedPolicy),
-        });
-    }
+      void checkUpdateUserTopicRequest(UserTopicVisibilityPolicy expectedPolicy) async {
+        check(connection.lastRequest).isA<http.Request>()
+          ..url.path.equals('/api/v1/user_topics')
+          ..bodyFields.deepEquals({
+            'stream_id': '${someChannel.streamId}',
+            'topic': topic,
+            'visibility_policy': jsonEncode(expectedPolicy),
+          });
+      }
 
-    testWidgets('unmuteInMutedChannel', (tester) async {
-      await setupToTopicActionSheet(tester,
-        isChannelMuted: true,
-        visibilityPolicy: UserTopicVisibilityPolicy.none);
-      await tester.tap(unmute);
-      await tester.pump();
-      checkUpdateUserTopicRequest(UserTopicVisibilityPolicy.unmuted);
-    });
+      testWidgets('unmuteInMutedChannel', (tester) async {
+        await setupToTopicActionSheet(tester,
+          isChannelMuted: true,
+          visibilityPolicy: UserTopicVisibilityPolicy.none);
+        await tester.tap(unmute);
+        await tester.pump();
+        checkUpdateUserTopicRequest(UserTopicVisibilityPolicy.unmuted);
+      });
 
-    testWidgets('unmute', (tester) async {
-      await setupToTopicActionSheet(tester,
-        isChannelMuted: false,
-        visibilityPolicy: UserTopicVisibilityPolicy.muted);
-      await tester.tap(unmute);
-      await tester.pump();
-      checkUpdateUserTopicRequest(UserTopicVisibilityPolicy.none);
-    });
+      testWidgets('unmute', (tester) async {
+        await setupToTopicActionSheet(tester,
+          isChannelMuted: false,
+          visibilityPolicy: UserTopicVisibilityPolicy.muted);
+        await tester.tap(unmute);
+        await tester.pump();
+        checkUpdateUserTopicRequest(UserTopicVisibilityPolicy.none);
+      });
 
-    testWidgets('mute', (tester) async {
-      await setupToTopicActionSheet(tester,
-        isChannelMuted: false,
-        visibilityPolicy: UserTopicVisibilityPolicy.none);
-      await tester.tap(mute);
-      await tester.pump();
-      checkUpdateUserTopicRequest(UserTopicVisibilityPolicy.muted);
-    });
+      testWidgets('mute', (tester) async {
+        await setupToTopicActionSheet(tester,
+          isChannelMuted: false,
+          visibilityPolicy: UserTopicVisibilityPolicy.none);
+        await tester.tap(mute);
+        await tester.pump();
+        checkUpdateUserTopicRequest(UserTopicVisibilityPolicy.muted);
+      });
 
-    testWidgets('follow', (tester) async {
-      await setupToTopicActionSheet(tester,
-        isChannelMuted: false,
-        visibilityPolicy: UserTopicVisibilityPolicy.none);
-      await tester.tap(follow);
-      await tester.pump();
-      checkUpdateUserTopicRequest(UserTopicVisibilityPolicy.followed);
-    });
+      testWidgets('follow', (tester) async {
+        await setupToTopicActionSheet(tester,
+          isChannelMuted: false,
+          visibilityPolicy: UserTopicVisibilityPolicy.none);
+        await tester.tap(follow);
+        await tester.pump();
+        checkUpdateUserTopicRequest(UserTopicVisibilityPolicy.followed);
+      });
 
-    testWidgets('unfollow', (tester) async {
-      await setupToTopicActionSheet(tester,
-        isChannelMuted: false,
-        visibilityPolicy: UserTopicVisibilityPolicy.followed);
-      await tester.tap(unfollow);
-      await tester.pump();
-      checkUpdateUserTopicRequest(UserTopicVisibilityPolicy.none);
-    });
+      testWidgets('unfollow', (tester) async {
+        await setupToTopicActionSheet(tester,
+          isChannelMuted: false,
+          visibilityPolicy: UserTopicVisibilityPolicy.followed);
+        await tester.tap(unfollow);
+        await tester.pump();
+        checkUpdateUserTopicRequest(UserTopicVisibilityPolicy.none);
+      });
 
-    testWidgets('request fails with an error dialog', (tester) async {
-      await setupToTopicActionSheet(tester,
-        isChannelMuted: false,
-        visibilityPolicy: UserTopicVisibilityPolicy.followed);
+      testWidgets('request fails with an error dialog', (tester) async {
+        await setupToTopicActionSheet(tester,
+          isChannelMuted: false,
+          visibilityPolicy: UserTopicVisibilityPolicy.followed);
 
-      connection.prepare(httpStatus: 400, json: {
-        'result': 'error', 'code': 'BAD_REQUEST', 'msg': ''});
-      await tester.tap(unfollow);
-      await tester.pumpAndSettle();
+        connection.prepare(httpStatus: 400, json: {
+          'result': 'error', 'code': 'BAD_REQUEST', 'msg': ''});
+        await tester.tap(unfollow);
+        await tester.pumpAndSettle();
+
+        checkErrorDialog(tester, expectedTitle: 'Failed to unfollow topic');
+      });
+
+      group('check expected buttons', () {
+        final testCases = [
+          (false, UserTopicVisibilityPolicy.muted,    [unmute, follow]),
+          (false, UserTopicVisibilityPolicy.none,     [mute, follow]),
+          (false, UserTopicVisibilityPolicy.unmuted,  [mute, follow]),
+          (false, UserTopicVisibilityPolicy.followed, [mute, unfollow]),
+
+          (true,  UserTopicVisibilityPolicy.muted,    [unmute, follow]),
+          (true,  UserTopicVisibilityPolicy.none,     [unmute, follow]),
+          (true,  UserTopicVisibilityPolicy.unmuted,  [mute, follow]),
+          (true,  UserTopicVisibilityPolicy.followed, [mute, unfollow]),
+
+          (null,  UserTopicVisibilityPolicy.none,     <Finder>[]),
+        ];
+
+        for (final (isChannelMuted, visibilityPolicy, buttons) in testCases) {
+          final description = 'isChannelMuted: ${isChannelMuted ?? "(not subscribed)"}, $visibilityPolicy';
+          testWidgets(description, (tester) async {
+            await setupToTopicActionSheet(tester,
+              isChannelMuted: isChannelMuted,
+              visibilityPolicy: visibilityPolicy);
+            checkButtons(buttons);
+          });
+        }
+      });
+
+      group('legacy: follow is unsupported when FL < 219', () {
+        final testCases = [
+          (false, UserTopicVisibilityPolicy.muted,    [unmute]),
+          (false, UserTopicVisibilityPolicy.none,     [mute]),
+          (false, UserTopicVisibilityPolicy.unmuted,  [mute]),
+          (false, UserTopicVisibilityPolicy.followed, [mute]),
+
+          (true,  UserTopicVisibilityPolicy.muted,    [unmute]),
+          (true,  UserTopicVisibilityPolicy.none,     [unmute]),
+          (true,  UserTopicVisibilityPolicy.unmuted,  [mute]),
+          (true,  UserTopicVisibilityPolicy.followed, [mute]),
+
+          (null,  UserTopicVisibilityPolicy.none,     <Finder>[]),
+        ];
+
+        for (final (isChannelMuted, visibilityPolicy, buttons) in testCases) {
+          final description = 'isChannelMuted: ${isChannelMuted ?? "(not subscribed)"}, $visibilityPolicy';
+          testWidgets(description, (tester) async {
+            await setupToTopicActionSheet(tester,
+              isChannelMuted: isChannelMuted,
+              visibilityPolicy: visibilityPolicy,
+              zulipFeatureLevel: 218);
+            checkButtons(buttons);
+          });
+        }
+      });
 
-      checkErrorDialog(tester, expectedTitle: 'Failed to unfollow topic');
+      group('legacy: unmute is unsupported when FL < 170', () {
+        final testCases = [
+          (false, UserTopicVisibilityPolicy.muted,    [unmute]),
+          (false, UserTopicVisibilityPolicy.none,     [mute]),
+          (false, UserTopicVisibilityPolicy.unmuted,  [mute]),
+          (false, UserTopicVisibilityPolicy.followed, [mute]),
+
+          (true,  UserTopicVisibilityPolicy.muted,    <Finder>[]),
+          (true,  UserTopicVisibilityPolicy.none,     <Finder>[]),
+          (true,  UserTopicVisibilityPolicy.unmuted,  <Finder>[]),
+          (true,  UserTopicVisibilityPolicy.followed, <Finder>[]),
+
+          (null,  UserTopicVisibilityPolicy.none,     <Finder>[]),
+        ];
+
+        for (final (isChannelMuted, visibilityPolicy, buttons) in testCases) {
+          final description = 'isChannelMuted: ${isChannelMuted ?? "(not subscribed)"}, $visibilityPolicy';
+          testWidgets(description, (tester) async {
+            await setupToTopicActionSheet(tester,
+              isChannelMuted: isChannelMuted,
+              visibilityPolicy: visibilityPolicy,
+              zulipFeatureLevel: 169);
+            checkButtons(buttons);
+          });
+        }
+      });
     });
 
-    group('check expected buttons', () {
-      final testCases = [
-        (false, UserTopicVisibilityPolicy.muted,    [unmute, follow]),
-        (false, UserTopicVisibilityPolicy.none,     [mute, follow]),
-        (false, UserTopicVisibilityPolicy.unmuted,  [mute, follow]),
-        (false, UserTopicVisibilityPolicy.followed, [mute, unfollow]),
-
-        (true,  UserTopicVisibilityPolicy.muted,    [unmute, follow]),
-        (true,  UserTopicVisibilityPolicy.none,     [unmute, follow]),
-        (true,  UserTopicVisibilityPolicy.unmuted,  [mute, follow]),
-        (true,  UserTopicVisibilityPolicy.followed, [mute, unfollow]),
-
-        (null,  UserTopicVisibilityPolicy.none,     <Finder>[]),
-      ];
-
-      for (final (isChannelMuted, visibilityPolicy, buttons) in testCases) {
-        final description = 'isChannelMuted: ${isChannelMuted ?? "(not subscribed)"}, $visibilityPolicy';
-        testWidgets(description, (tester) async {
-          await setupToTopicActionSheet(tester,
-            isChannelMuted: isChannelMuted,
-            visibilityPolicy: visibilityPolicy);
-          checkButtons(buttons);
-        });
+    group('ResolveUnresolveButton', () {
+      void checkRequest(int messageId, String topic) {
+        check(connection.takeRequests()).single.isA<http.Request>()
+          ..method.equals('PATCH')
+          ..url.path.equals('/api/v1/messages/$messageId')
+          ..bodyFields.deepEquals({
+            'topic': topic,
+            'propagate_mode': 'change_all',
+            'send_notification_to_old_thread': 'false',
+            'send_notification_to_new_thread': 'true',
+          });
       }
+
+      testWidgets('resolve: happy path from inbox; message in Unreads but not MessageStore', (tester) async {
+        final message = eg.streamMessage(stream: someChannel, topic: 'zulip');
+        await prepare(
+          topic: 'zulip',
+          unreadMsgs: eg.unreadMsgs(count: 1,
+            channels: [eg.unreadChannelMsgs(
+              streamId: someChannel.streamId,
+              topic: 'zulip',
+              unreadMessageIds: [message.id],
+            )]));
+        await showFromInbox(tester, topic: 'zulip');
+        check(store.messages).not((it) => it.containsKey(message.id));
+        connection.prepare(json: UpdateMessageResult().toJson());
+        await tester.tap(findButtonForLabel('Mark as resolved'));
+        await tester.pumpAndSettle();
+
+        checkNoErrorDialog(tester);
+        checkRequest(message.id, '✔ zulip');
+      });
+
+      testWidgets('resolve: happy path from inbox; message in Unreads and MessageStore', (tester) async {
+        final message = eg.streamMessage(stream: someChannel, topic: 'zulip');
+        await prepare(topic: 'zulip');
+        await store.addMessage(message);
+        await showFromInbox(tester, topic: 'zulip');
+        check(store.unreads.isUnread(message.id)).isNotNull().isTrue();
+        check(store.messages)[message.id].isNotNull();
+        connection.prepare(json: UpdateMessageResult().toJson());
+        await tester.tap(findButtonForLabel('Mark as resolved'));
+        await tester.pumpAndSettle();
+
+        checkNoErrorDialog(tester);
+        checkRequest(message.id, '✔ zulip');
+      });
+
+      testWidgets('unresolve: happy path', (tester) async {
+        final message = eg.streamMessage(stream: someChannel, topic: '✔ zulip');
+        await prepare(topic: '✔ zulip');
+        await showFromAppBar(tester, topic: '✔ zulip', messages: [message]);
+        connection.takeRequests();
+        connection.prepare(json: UpdateMessageResult().toJson());
+        await tester.tap(findButtonForLabel('Mark as unresolved'));
+        await tester.pumpAndSettle();
+
+        checkNoErrorDialog(tester);
+        checkRequest(message.id, 'zulip');
+      });
+
+      testWidgets('unresolve: weird prefix', (tester) async {
+        final message = eg.streamMessage(stream: someChannel, topic: '✔ ✔ zulip');
+        await prepare(topic: '✔ ✔ zulip');
+        await showFromAppBar(tester, topic: '✔ ✔ zulip', messages: [message]);
+        connection.takeRequests();
+        connection.prepare(json: UpdateMessageResult().toJson());
+        await tester.tap(findButtonForLabel('Mark as unresolved'));
+        await tester.pumpAndSettle();
+
+        checkNoErrorDialog(tester);
+        checkRequest(message.id, 'zulip');
+      });
+
+      testWidgets('resolve: request fails', (tester) async {
+        final message = eg.streamMessage(stream: someChannel, topic: 'zulip');
+        await prepare(topic: 'zulip');
+        await showFromRecipientHeader(tester, message: message);
+        connection.takeRequests();
+        connection.prepare(exception: http.ClientException('Oops'));
+        await tester.tap(findButtonForLabel('Mark as resolved'));
+        await tester.pumpAndSettle();
+        checkRequest(message.id, '✔ zulip');
+
+        checkErrorDialog(tester,
+          expectedTitle: 'Failed to mark topic as resolved');
+      });
+
+      testWidgets('unresolve: request fails', (tester) async {
+        final message = eg.streamMessage(stream: someChannel, topic: '✔ zulip');
+        await prepare(topic: '✔ zulip');
+        await showFromRecipientHeader(tester, message: message);
+        connection.takeRequests();
+        connection.prepare(exception: http.ClientException('Oops'));
+        await tester.tap(findButtonForLabel('Mark as unresolved'));
+        await tester.pumpAndSettle();
+        checkRequest(message.id, 'zulip');
+
+        checkErrorDialog(tester,
+          expectedTitle: 'Failed to mark topic as unresolved');
+      });
     });
+  });
 
-    group('legacy: follow is unsupported when FL < 219', () {
-      final testCases = [
-        (false, UserTopicVisibilityPolicy.muted,    [unmute]),
-        (false, UserTopicVisibilityPolicy.none,     [mute]),
-        (false, UserTopicVisibilityPolicy.unmuted,  [mute]),
-        (false, UserTopicVisibilityPolicy.followed, [mute]),
-
-        (true,  UserTopicVisibilityPolicy.muted,    [unmute]),
-        (true,  UserTopicVisibilityPolicy.none,     [unmute]),
-        (true,  UserTopicVisibilityPolicy.unmuted,  [mute]),
-        (true,  UserTopicVisibilityPolicy.followed, [mute]),
-
-        (null,  UserTopicVisibilityPolicy.none,     <Finder>[]),
-      ];
-
-      for (final (isChannelMuted, visibilityPolicy, buttons) in testCases) {
-        final description = 'isChannelMuted: ${isChannelMuted ?? "(not subscribed)"}, $visibilityPolicy';
-        testWidgets(description, (tester) async {
-          await setupToTopicActionSheet(tester,
-            isChannelMuted: isChannelMuted,
-            visibilityPolicy: visibilityPolicy,
-            zulipFeatureLevel: 218);
-          checkButtons(buttons);
+  group('message action sheet', () {
+    group('ReactionButtons', () {
+      final popularCandidates = EmojiStore.popularEmojiCandidates;
+
+      for (final emoji in popularCandidates) {
+        final emojiDisplay = emoji.emojiDisplay as UnicodeEmojiDisplay;
+
+        Future<void> tapButton(WidgetTester tester) async {
+          await tester.tap(find.descendant(
+            of: find.byType(BottomSheet),
+            matching: find.text(emojiDisplay.emojiUnicode)));
+        }
+
+        testWidgets('${emoji.emojiName} adding success', (tester) async {
+          final message = eg.streamMessage();
+          await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+
+          connection.prepare(json: {});
+          await tapButton(tester);
+          await tester.pump(Duration.zero);
+
+          check(connection.lastRequest).isA<http.Request>()
+            ..method.equals('POST')
+            ..url.path.equals('/api/v1/messages/${message.id}/reactions')
+            ..bodyFields.deepEquals({
+                'reaction_type': 'unicode_emoji',
+                'emoji_code': emoji.emojiCode,
+                'emoji_name': emoji.emojiName,
+              });
+        });
+
+        testWidgets('${emoji.emojiName} removing success', (tester) async {
+          final message = eg.streamMessage(
+            reactions: [Reaction(
+              emojiName: emoji.emojiName,
+              emojiCode: emoji.emojiCode,
+              reactionType: ReactionType.unicodeEmoji,
+              userId: eg.selfAccount.userId)]
+          );
+          await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+
+          connection.prepare(json: {});
+          await tapButton(tester);
+          await tester.pump(Duration.zero);
+
+          check(connection.lastRequest).isA<http.Request>()
+            ..method.equals('DELETE')
+            ..url.path.equals('/api/v1/messages/${message.id}/reactions')
+            ..bodyFields.deepEquals({
+                'reaction_type': 'unicode_emoji',
+                'emoji_code': emoji.emojiCode,
+                'emoji_name': emoji.emojiName,
+              });
         });
-      }
-    });
 
-    group('legacy: unmute is unsupported when FL < 170', () {
-      final testCases = [
-        (false, UserTopicVisibilityPolicy.muted,    [unmute]),
-        (false, UserTopicVisibilityPolicy.none,     [mute]),
-        (false, UserTopicVisibilityPolicy.unmuted,  [mute]),
-        (false, UserTopicVisibilityPolicy.followed, [mute]),
-
-        (true,  UserTopicVisibilityPolicy.muted,    <Finder>[]),
-        (true,  UserTopicVisibilityPolicy.none,     <Finder>[]),
-        (true,  UserTopicVisibilityPolicy.unmuted,  <Finder>[]),
-        (true,  UserTopicVisibilityPolicy.followed, <Finder>[]),
-
-        (null,  UserTopicVisibilityPolicy.none,     <Finder>[]),
-      ];
-
-      for (final (isChannelMuted, visibilityPolicy, buttons) in testCases) {
-        final description = 'isChannelMuted: ${isChannelMuted ?? "(not subscribed)"}, $visibilityPolicy';
-        testWidgets(description, (tester) async {
-          await setupToTopicActionSheet(tester,
-            isChannelMuted: isChannelMuted,
-            visibilityPolicy: visibilityPolicy,
-            zulipFeatureLevel: 169);
-          checkButtons(buttons);
+        testWidgets('${emoji.emojiName} request has an error', (tester) async {
+          final message = eg.streamMessage();
+          await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+
+          connection.prepare(httpStatus: 400, json: {
+            'code': 'BAD_REQUEST',
+            'msg': 'Invalid message(s)',
+            'result': 'error',
+          });
+          await tapButton(tester);
+          await tester.pump(Duration.zero); // error arrives; error dialog shows
+
+          await tester.tap(find.byWidget(checkErrorDialog(tester,
+            expectedTitle: 'Adding reaction failed',
+            expectedMessage: 'Invalid message(s)')));
         });
       }
     });
-  });
-
-  group('ReactionButtons', () {
-    final popularCandidates = EmojiStore.popularEmojiCandidates;
 
-    for (final emoji in popularCandidates) {
-      final emojiDisplay = emoji.emojiDisplay as UnicodeEmojiDisplay;
-
-      Future<void> tapButton(WidgetTester tester) async {
+    group('StarButton', () {
+      Future<void> tapButton(WidgetTester tester, {bool starred = false}) async {
+        // Starred messages include the same icon so we need to
+        // match only by descendants of [BottomSheet].
+        await tester.ensureVisible(find.descendant(
+          of: find.byType(BottomSheet),
+          matching: find.byIcon(starred ? ZulipIcons.star_filled : ZulipIcons.star, skipOffstage: false)));
         await tester.tap(find.descendant(
           of: find.byType(BottomSheet),
-          matching: find.text(emojiDisplay.emojiUnicode)));
+          matching: find.byIcon(starred ? ZulipIcons.star_filled : ZulipIcons.star)));
+        await tester.pump(); // [MenuItemButton.onPressed] called in a post-frame callback: flutter/flutter@e4a39fa2e
       }
 
-      testWidgets('${emoji.emojiName} adding success', (tester) async {
-        final message = eg.streamMessage();
+      testWidgets('star success', (tester) async {
+        final message = eg.streamMessage(flags: []);
         await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
 
         connection.prepare(json: {});
@@ -408,41 +667,36 @@ void main() {
 
         check(connection.lastRequest).isA<http.Request>()
           ..method.equals('POST')
-          ..url.path.equals('/api/v1/messages/${message.id}/reactions')
+          ..url.path.equals('/api/v1/messages/flags')
           ..bodyFields.deepEquals({
-              'reaction_type': 'unicode_emoji',
-              'emoji_code': emoji.emojiCode,
-              'emoji_name': emoji.emojiName,
-            });
+            'messages': jsonEncode([message.id]),
+            'op': 'add',
+            'flag': 'starred',
+          });
       });
 
-      testWidgets('${emoji.emojiName} removing success', (tester) async {
-        final message = eg.streamMessage(
-          reactions: [Reaction(
-            emojiName: emoji.emojiName,
-            emojiCode: emoji.emojiCode,
-            reactionType: ReactionType.unicodeEmoji,
-            userId: eg.selfAccount.userId)]
-        );
+      testWidgets('unstar success', (tester) async {
+        final message = eg.streamMessage(flags: [MessageFlag.starred]);
         await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
 
         connection.prepare(json: {});
-        await tapButton(tester);
+        await tapButton(tester, starred: true);
         await tester.pump(Duration.zero);
 
         check(connection.lastRequest).isA<http.Request>()
-          ..method.equals('DELETE')
-          ..url.path.equals('/api/v1/messages/${message.id}/reactions')
+          ..method.equals('POST')
+          ..url.path.equals('/api/v1/messages/flags')
           ..bodyFields.deepEquals({
-              'reaction_type': 'unicode_emoji',
-              'emoji_code': emoji.emojiCode,
-              'emoji_name': emoji.emojiName,
-            });
+            'messages': jsonEncode([message.id]),
+            'op': 'remove',
+            'flag': 'starred',
+          });
       });
 
-      testWidgets('${emoji.emojiName} request has an error', (tester) async {
-        final message = eg.streamMessage();
+      testWidgets('star request has an error', (tester) async {
+        final message = eg.streamMessage(flags: []);
         await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+        final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
 
         connection.prepare(httpStatus: 400, json: {
           'code': 'BAD_REQUEST',
@@ -453,180 +707,94 @@ void main() {
         await tester.pump(Duration.zero); // error arrives; error dialog shows
 
         await tester.tap(find.byWidget(checkErrorDialog(tester,
-          expectedTitle: 'Adding reaction failed',
+          expectedTitle: zulipLocalizations.errorStarMessageFailedTitle,
           expectedMessage: 'Invalid message(s)')));
       });
-    }
-  });
 
-  group('StarButton', () {
-    Future<void> tapButton(WidgetTester tester, {bool starred = false}) async {
-      // Starred messages include the same icon so we need to
-      // match only by descendants of [BottomSheet].
-      await tester.ensureVisible(find.descendant(
-        of: find.byType(BottomSheet),
-        matching: find.byIcon(starred ? ZulipIcons.star_filled : ZulipIcons.star, skipOffstage: false)));
-      await tester.tap(find.descendant(
-        of: find.byType(BottomSheet),
-        matching: find.byIcon(starred ? ZulipIcons.star_filled : ZulipIcons.star)));
-      await tester.pump(); // [MenuItemButton.onPressed] called in a post-frame callback: flutter/flutter@e4a39fa2e
-    }
-
-    testWidgets('star success', (tester) async {
-      final message = eg.streamMessage(flags: []);
-      await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
-
-      connection.prepare(json: {});
-      await tapButton(tester);
-      await tester.pump(Duration.zero);
-
-      check(connection.lastRequest).isA<http.Request>()
-        ..method.equals('POST')
-        ..url.path.equals('/api/v1/messages/flags')
-        ..bodyFields.deepEquals({
-          'messages': jsonEncode([message.id]),
-          'op': 'add',
-          'flag': 'starred',
-        });
-    });
+      testWidgets('unstar request has an error', (tester) async {
+        final message = eg.streamMessage(flags: [MessageFlag.starred]);
+        await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+        final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
 
-    testWidgets('unstar success', (tester) async {
-      final message = eg.streamMessage(flags: [MessageFlag.starred]);
-      await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
-
-      connection.prepare(json: {});
-      await tapButton(tester, starred: true);
-      await tester.pump(Duration.zero);
-
-      check(connection.lastRequest).isA<http.Request>()
-        ..method.equals('POST')
-        ..url.path.equals('/api/v1/messages/flags')
-        ..bodyFields.deepEquals({
-          'messages': jsonEncode([message.id]),
-          'op': 'remove',
-          'flag': 'starred',
+        connection.prepare(httpStatus: 400, json: {
+          'code': 'BAD_REQUEST',
+          'msg': 'Invalid message(s)',
+          'result': 'error',
         });
-    });
-
-    testWidgets('star request has an error', (tester) async {
-      final message = eg.streamMessage(flags: []);
-      await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
-      final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
-
-      connection.prepare(httpStatus: 400, json: {
-        'code': 'BAD_REQUEST',
-        'msg': 'Invalid message(s)',
-        'result': 'error',
-      });
-      await tapButton(tester);
-      await tester.pump(Duration.zero); // error arrives; error dialog shows
-
-      await tester.tap(find.byWidget(checkErrorDialog(tester,
-        expectedTitle: zulipLocalizations.errorStarMessageFailedTitle,
-        expectedMessage: 'Invalid message(s)')));
-    });
-
-    testWidgets('unstar request has an error', (tester) async {
-      final message = eg.streamMessage(flags: [MessageFlag.starred]);
-      await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
-      final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
+        await tapButton(tester, starred: true);
+        await tester.pump(Duration.zero); // error arrives; error dialog shows
 
-      connection.prepare(httpStatus: 400, json: {
-        'code': 'BAD_REQUEST',
-        'msg': 'Invalid message(s)',
-        'result': 'error',
+        await tester.tap(find.byWidget(checkErrorDialog(tester,
+          expectedTitle: zulipLocalizations.errorUnstarMessageFailedTitle,
+          expectedMessage: 'Invalid message(s)')));
       });
-      await tapButton(tester, starred: true);
-      await tester.pump(Duration.zero); // error arrives; error dialog shows
-
-      await tester.tap(find.byWidget(checkErrorDialog(tester,
-        expectedTitle: zulipLocalizations.errorUnstarMessageFailedTitle,
-        expectedMessage: 'Invalid message(s)')));
     });
-  });
-
-  group('QuoteAndReplyButton', () {
-    ComposeBoxController? findComposeBoxController(WidgetTester tester) {
-      return tester.stateList<ComposeBoxState>(find.byType(ComposeBox))
-        .singleOrNull?.controller;
-    }
 
-    Widget? findQuoteAndReplyButton(WidgetTester tester) {
-      return tester.widgetList(find.byIcon(ZulipIcons.format_quote)).singleOrNull;
-    }
+    group('QuoteAndReplyButton', () {
+      ComposeBoxController? findComposeBoxController(WidgetTester tester) {
+        return tester.stateList<ComposeBoxState>(find.byType(ComposeBox))
+          .singleOrNull?.controller;
+      }
 
-    /// Simulates tapping the quote-and-reply button in the message action sheet.
-    ///
-    /// Checks that there is a quote-and-reply button.
-    Future<void> tapQuoteAndReplyButton(WidgetTester tester) async {
-      await tester.ensureVisible(find.byIcon(ZulipIcons.format_quote, skipOffstage: false));
-      final quoteAndReplyButton = findQuoteAndReplyButton(tester);
-      check(quoteAndReplyButton).isNotNull();
-      TypingNotifier.debugEnable = false;
-      addTearDown(TypingNotifier.debugReset);
-      await tester.tap(find.byWidget(quoteAndReplyButton!));
-      await tester.pump(); // [MenuItemButton.onPressed] called in a post-frame callback: flutter/flutter@e4a39fa2e
-    }
+      Widget? findQuoteAndReplyButton(WidgetTester tester) {
+        return tester.widgetList(find.byIcon(ZulipIcons.format_quote)).singleOrNull;
+      }
 
-    void checkLoadingState(PerAccountStore store, ComposeContentController contentController, {
-      required TextEditingValue valueBefore,
-      required Message message,
-    }) {
-      check(contentController).value.equals((ComposeContentController()
-        ..value = valueBefore
-        ..insertPadded(quoteAndReplyPlaceholder(store, message: message))
-      ).value);
-      check(contentController).validationErrors.contains(ContentValidationError.quoteAndReplyInProgress);
-    }
+      /// Simulates tapping the quote-and-reply button in the message action sheet.
+      ///
+      /// Checks that there is a quote-and-reply button.
+      Future<void> tapQuoteAndReplyButton(WidgetTester tester) async {
+        await tester.ensureVisible(find.byIcon(ZulipIcons.format_quote, skipOffstage: false));
+        final quoteAndReplyButton = findQuoteAndReplyButton(tester);
+        check(quoteAndReplyButton).isNotNull();
+        TypingNotifier.debugEnable = false;
+        addTearDown(TypingNotifier.debugReset);
+        await tester.tap(find.byWidget(quoteAndReplyButton!));
+        await tester.pump(); // [MenuItemButton.onPressed] called in a post-frame callback: flutter/flutter@e4a39fa2e
+      }
 
-    void checkSuccessState(PerAccountStore store, ComposeContentController contentController, {
-      required TextEditingValue valueBefore,
-      required Message message,
-      required String rawContent,
-    }) {
-      final builder = ComposeContentController()
-        ..value = valueBefore
-        ..insertPadded(quoteAndReply(store, message: message, rawContent: rawContent));
-      if (!valueBefore.selection.isValid) {
-        // (At the end of the process, we focus the input, which puts a cursor
-        // at text's end, if there was no cursor at the time.)
-        builder.selection = TextSelection.collapsed(offset: builder.text.length);
+      void checkLoadingState(PerAccountStore store, ComposeContentController contentController, {
+        required TextEditingValue valueBefore,
+        required Message message,
+      }) {
+        check(contentController).value.equals((ComposeContentController()
+          ..value = valueBefore
+          ..insertPadded(quoteAndReplyPlaceholder(
+              GlobalLocalizations.zulipLocalizations, store, message: message))
+        ).value);
+        check(contentController).validationErrors.contains(ContentValidationError.quoteAndReplyInProgress);
       }
-      check(contentController).value.equals(builder.value);
-      check(contentController).not((it) => it.validationErrors.contains(ContentValidationError.quoteAndReplyInProgress));
-    }
 
-    testWidgets('in channel narrow', (tester) async {
-      final message = eg.streamMessage();
-      await setupToMessageActionSheet(tester, message: message, narrow: ChannelNarrow(message.streamId));
-
-      final composeBoxController = findComposeBoxController(tester) as StreamComposeBoxController;
-      final contentController = composeBoxController.content;
-
-      // Ensure channel-topics are loaded before testing quote & reply behavior
-      connection.prepare(body:
-        jsonEncode(GetStreamTopicsResult(topics: [eg.getStreamTopicsEntry()]).toJson()));
-      final topicController = composeBoxController.topic;
-      topicController.value = const TextEditingValue(text: kNoTopicTopic);
-
-      final valueBefore = contentController.value;
-      prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world');
-      await tapQuoteAndReplyButton(tester);
-      checkLoadingState(store, contentController, valueBefore: valueBefore, message: message);
-      await tester.pump(Duration.zero); // message is fetched; compose box updates
-      check(composeBoxController.contentFocusNode.hasFocus).isTrue();
-      checkSuccessState(store, contentController,
-        valueBefore: valueBefore, message: message, rawContent: 'Hello world');
-    });
+      void checkSuccessState(PerAccountStore store, ComposeContentController contentController, {
+        required TextEditingValue valueBefore,
+        required Message message,
+        required String rawContent,
+      }) {
+        final builder = ComposeContentController()
+          ..value = valueBefore
+          ..insertPadded(quoteAndReply(store, message: message, rawContent: rawContent));
+        if (!valueBefore.selection.isValid) {
+          // (At the end of the process, we focus the input, which puts a cursor
+          // at text's end, if there was no cursor at the time.)
+          builder.selection = TextSelection.collapsed(offset: builder.text.length);
+        }
+        check(contentController).value.equals(builder.value);
+        check(contentController).not((it) => it.validationErrors.contains(ContentValidationError.quoteAndReplyInProgress));
+      }
 
-    group('in topic narrow', () {
-      testWidgets('smoke', (tester) async {
+      testWidgets('in channel narrow', (tester) async {
         final message = eg.streamMessage();
-        await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+        await setupToMessageActionSheet(tester, message: message, narrow: ChannelNarrow(message.streamId));
 
-        final composeBoxController = findComposeBoxController(tester)!;
+        final composeBoxController = findComposeBoxController(tester) as StreamComposeBoxController;
         final contentController = composeBoxController.content;
 
+        // Ensure channel-topics are loaded before testing quote & reply behavior
+        connection.prepare(body:
+          jsonEncode(GetStreamTopicsResult(topics: [eg.getStreamTopicsEntry()]).toJson()));
+        final topicController = composeBoxController.topic;
+        topicController.value = const TextEditingValue(text: kNoTopicTopic);
+
         final valueBefore = contentController.value;
         prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world');
         await tapQuoteAndReplyButton(tester);
@@ -637,383 +805,402 @@ void main() {
           valueBefore: valueBefore, message: message, rawContent: 'Hello world');
       });
 
-      testWidgets('no error if user lost posting permission after action sheet opened', (tester) async {
-        final stream = eg.stream();
-        final message = eg.streamMessage(stream: stream);
-        await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+      group('in topic narrow', () {
+        testWidgets('smoke', (tester) async {
+          final message = eg.streamMessage();
+          await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+
+          final composeBoxController = findComposeBoxController(tester)!;
+          final contentController = composeBoxController.content;
+
+          final valueBefore = contentController.value;
+          prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world');
+          await tapQuoteAndReplyButton(tester);
+          checkLoadingState(store, contentController, valueBefore: valueBefore, message: message);
+          await tester.pump(Duration.zero); // message is fetched; compose box updates
+          check(composeBoxController.contentFocusNode.hasFocus).isTrue();
+          checkSuccessState(store, contentController,
+            valueBefore: valueBefore, message: message, rawContent: 'Hello world');
+        });
 
-        await store.handleEvent(RealmUserUpdateEvent(id: 1, userId: eg.selfUser.userId,
-          role: UserRole.guest));
-        await store.handleEvent(eg.channelUpdateEvent(stream,
-          property: ChannelPropertyName.channelPostPolicy,
-          value: ChannelPostPolicy.administrators));
-        await tester.pump();
+        testWidgets('no error if user lost posting permission after action sheet opened', (tester) async {
+          final stream = eg.stream();
+          final message = eg.streamMessage(stream: stream);
+          await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
 
-        await tapQuoteAndReplyButton(tester);
-        // no error
+          await store.handleEvent(RealmUserUpdateEvent(id: 1, userId: eg.selfUser.userId,
+            role: UserRole.guest));
+          await store.handleEvent(eg.channelUpdateEvent(stream,
+            property: ChannelPropertyName.channelPostPolicy,
+            value: ChannelPostPolicy.administrators));
+          await tester.pump();
+
+          await tapQuoteAndReplyButton(tester);
+          // no error
+        });
       });
-    });
 
-    group('in DM narrow', () {
-      testWidgets('smoke', (tester) async {
-        final message = eg.dmMessage(from: eg.selfUser, to: [eg.otherUser]);
-        await setupToMessageActionSheet(tester,
-          message: message, narrow: DmNarrow.ofMessage(message, selfUserId: eg.selfUser.userId));
+      group('in DM narrow', () {
+        testWidgets('smoke', (tester) async {
+          final message = eg.dmMessage(from: eg.selfUser, to: [eg.otherUser]);
+          await setupToMessageActionSheet(tester,
+            message: message, narrow: DmNarrow.ofMessage(message, selfUserId: eg.selfUser.userId));
+
+          final composeBoxController = findComposeBoxController(tester)!;
+          final contentController = composeBoxController.content;
+
+          final valueBefore = contentController.value;
+          prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world');
+          await tapQuoteAndReplyButton(tester);
+          checkLoadingState(store, contentController, valueBefore: valueBefore, message: message);
+          await tester.pump(Duration.zero); // message is fetched; compose box updates
+          check(composeBoxController.contentFocusNode.hasFocus).isTrue();
+          checkSuccessState(store, contentController,
+            valueBefore: valueBefore, message: message, rawContent: 'Hello world');
+        });
+
+        testWidgets('no error if recipient was deactivated while raw-content request in progress', (tester) async {
+          final message = eg.dmMessage(from: eg.selfUser, to: [eg.otherUser]);
+          await setupToMessageActionSheet(tester,
+            message: message,
+            narrow: DmNarrow.ofMessage(message, selfUserId: eg.selfUser.userId));
+
+          prepareRawContentResponseSuccess(
+            message: message,
+            rawContent: 'Hello world',
+            delay: const Duration(seconds: 5),
+          );
+          await tapQuoteAndReplyButton(tester);
+          await tester.pump(const Duration(seconds: 1)); // message not yet fetched
+
+          await store.handleEvent(RealmUserUpdateEvent(id: 1, userId: eg.otherUser.userId,
+            isActive: false));
+          await tester.pump();
+          // no error
+          await tester.pump(const Duration(seconds: 4));
+        });
+      });
+
+      testWidgets('request has an error', (tester) async {
+        final message = eg.streamMessage();
+        await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
 
         final composeBoxController = findComposeBoxController(tester)!;
         final contentController = composeBoxController.content;
 
-        final valueBefore = contentController.value;
-        prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world');
+        final valueBefore = contentController.value = TextEditingValue.empty;
+        prepareRawContentResponseError();
         await tapQuoteAndReplyButton(tester);
         checkLoadingState(store, contentController, valueBefore: valueBefore, message: message);
-        await tester.pump(Duration.zero); // message is fetched; compose box updates
-        check(composeBoxController.contentFocusNode.hasFocus).isTrue();
-        checkSuccessState(store, contentController,
-          valueBefore: valueBefore, message: message, rawContent: 'Hello world');
+        await tester.pump(Duration.zero); // error arrives; error dialog shows
+
+        await tester.tap(find.byWidget(checkErrorDialog(tester,
+          expectedTitle: 'Quotation failed',
+          expectedMessage: 'That message does not seem to exist.',
+        )));
+
+        check(contentController.value).equals(const TextEditingValue(
+          // The placeholder was removed. (A newline from the placeholder's
+          // insertPadded remains; I guess ideally we'd try to prevent that.)
+          text: '\n',
+
+          // (At the end of the process, we focus the input.)
+          selection: TextSelection.collapsed(offset: 1), //
+        ));
       });
 
-      testWidgets('no error if recipient was deactivated while raw-content request in progress', (tester) async {
-        final message = eg.dmMessage(from: eg.selfUser, to: [eg.otherUser]);
-        await setupToMessageActionSheet(tester,
-          message: message,
-          narrow: DmNarrow.ofMessage(message, selfUserId: eg.selfUser.userId));
+      testWidgets('not offered in CombinedFeedNarrow (composing to reply is not yet supported)', (tester) async {
+        final message = eg.streamMessage();
+        await setupToMessageActionSheet(tester, message: message, narrow: const CombinedFeedNarrow());
+        check(findQuoteAndReplyButton(tester)).isNull();
+      });
 
-        prepareRawContentResponseSuccess(
-          message: message,
-          rawContent: 'Hello world',
-          delay: const Duration(seconds: 5),
-        );
-        await tapQuoteAndReplyButton(tester);
-        await tester.pump(const Duration(seconds: 1)); // message not yet fetched
+      testWidgets('not offered in MentionsNarrow (composing to reply is not yet supported)', (tester) async {
+        final message = eg.streamMessage(flags: [MessageFlag.mentioned]);
+        await setupToMessageActionSheet(tester, message: message, narrow: const MentionsNarrow());
+        check(findQuoteAndReplyButton(tester)).isNull();
+      });
 
-        await store.handleEvent(RealmUserUpdateEvent(id: 1, userId: eg.otherUser.userId,
-          isActive: false));
-        await tester.pump();
-        // no error
-        await tester.pump(const Duration(seconds: 4));
+      testWidgets('not offered in StarredMessagesNarrow (composing to reply is not yet supported)', (tester) async {
+        final message = eg.streamMessage(flags: [MessageFlag.starred]);
+        await setupToMessageActionSheet(tester, message: message, narrow: const StarredMessagesNarrow());
+        check(findQuoteAndReplyButton(tester)).isNull();
       });
     });
 
-    testWidgets('request has an error', (tester) async {
-      final message = eg.streamMessage();
-      await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
-
-      final composeBoxController = findComposeBoxController(tester)!;
-      final contentController = composeBoxController.content;
-
-      final valueBefore = contentController.value = TextEditingValue.empty;
-      prepareRawContentResponseError();
-      await tapQuoteAndReplyButton(tester);
-      checkLoadingState(store, contentController, valueBefore: valueBefore, message: message);
-      await tester.pump(Duration.zero); // error arrives; error dialog shows
+    group('MarkAsUnread', () {
+      testWidgets('not visible if message is not read', (tester) async {
+        final unreadMessage = eg.streamMessage(flags: []);
+        await setupToMessageActionSheet(tester, message: unreadMessage, narrow: TopicNarrow.ofMessage(unreadMessage));
 
-      await tester.tap(find.byWidget(checkErrorDialog(tester,
-        expectedTitle: 'Quotation failed',
-        expectedMessage: 'That message does not seem to exist.',
-      )));
+        check(find.byIcon(Icons.mark_chat_unread_outlined).evaluate()).isEmpty();
+      });
 
-      check(contentController.value).equals(const TextEditingValue(
-        // The placeholder was removed. (A newline from the placeholder's
-        // insertPadded remains; I guess ideally we'd try to prevent that.)
-        text: '\n',
+      testWidgets('visible if message is read', (tester) async {
+        final readMessage = eg.streamMessage(flags: [MessageFlag.read]);
+        await setupToMessageActionSheet(tester, message: readMessage, narrow: TopicNarrow.ofMessage(readMessage));
 
-        // (At the end of the process, we focus the input.)
-        selection: TextSelection.collapsed(offset: 1), //
-      ));
-    });
+        check(find.byIcon(Icons.mark_chat_unread_outlined).evaluate()).single;
+      });
 
-    testWidgets('not offered in CombinedFeedNarrow (composing to reply is not yet supported)', (tester) async {
-      final message = eg.streamMessage();
-      await setupToMessageActionSheet(tester, message: message, narrow: const CombinedFeedNarrow());
-      check(findQuoteAndReplyButton(tester)).isNull();
-    });
+      group('onPressed', () {
+        testWidgets('smoke test', (tester) async {
+          final message = eg.streamMessage(flags: [MessageFlag.read]);
+          await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+
+          connection.prepare(json: UpdateMessageFlagsForNarrowResult(
+            processedCount: 11, updatedCount: 3,
+            firstProcessedId: 1, lastProcessedId: 1980,
+            foundOldest: true, foundNewest: true).toJson());
+
+          await tester.ensureVisible(find.byIcon(Icons.mark_chat_unread_outlined, skipOffstage: false));
+          await tester.tap(find.byIcon(Icons.mark_chat_unread_outlined, skipOffstage: false));
+          await tester.pumpAndSettle();
+          check(connection.lastRequest).isA<http.Request>()
+            ..method.equals('POST')
+            ..url.path.equals('/api/v1/messages/flags/narrow')
+            ..bodyFields.deepEquals({
+                'anchor': '${message.id}',
+                'include_anchor': 'true',
+                'num_before': '0',
+                'num_after': '1000',
+                'narrow': jsonEncode(TopicNarrow.ofMessage(message).apiEncode()),
+                'op': 'remove',
+                'flag': 'read',
+              });
+        });
 
-    testWidgets('not offered in MentionsNarrow (composing to reply is not yet supported)', (tester) async {
-      final message = eg.streamMessage(flags: [MessageFlag.mentioned]);
-      await setupToMessageActionSheet(tester, message: message, narrow: const MentionsNarrow());
-      check(findQuoteAndReplyButton(tester)).isNull();
-    });
+        testWidgets('on topic move, acts on new topic', (tester) async {
+          final stream = eg.stream();
+          const topic = 'old topic';
+          final message = eg.streamMessage(flags: [MessageFlag.read],
+            stream: stream, topic: topic);
+          await setupToMessageActionSheet(tester, message: message,
+            narrow: TopicNarrow.ofMessage(message));
+
+          // Get the action sheet fully deployed while the old narrow applies.
+          // (This way we maximize the range of potential bugs this test can catch,
+          // by giving the code maximum opportunity to latch onto the old topic.)
+          await tester.pumpAndSettle();
+
+          final newStream = eg.stream();
+          const newTopic = 'other topic';
+          // This result isn't quite realistic for this request: it should get
+          // the updated channel/stream ID and topic, because we don't even
+          // start the request until after we get the move event.
+          // But constructing the right result is annoying at the moment, and
+          // it doesn't matter anyway: [MessageStoreImpl.reconcileMessages] will
+          // keep the version updated by the event.  If that somehow changes in
+          // some future refactor, it'll cause this test to fail.
+          connection.prepare(json: eg.newestGetMessagesResult(
+            foundOldest: true, messages: [message]).toJson());
+          await store.handleEvent(eg.updateMessageEventMoveFrom(
+            newStreamId: newStream.streamId, newTopicStr: newTopic,
+            propagateMode: PropagateMode.changeAll,
+            origMessages: [message]));
+
+          connection.prepare(json: UpdateMessageFlagsForNarrowResult(
+            processedCount: 11, updatedCount: 3,
+            firstProcessedId: 1, lastProcessedId: 1980,
+            foundOldest: true, foundNewest: true).toJson());
+          await tester.tap(find.byIcon(Icons.mark_chat_unread_outlined, skipOffstage: false));
+          await tester.pumpAndSettle();
+          check(connection.lastRequest).isA<http.Request>()
+            ..method.equals('POST')
+            ..url.path.equals('/api/v1/messages/flags/narrow')
+            ..bodyFields['narrow'].equals(
+                jsonEncode(eg.topicNarrow(newStream.streamId, newTopic).apiEncode()));
+        });
 
-    testWidgets('not offered in StarredMessagesNarrow (composing to reply is not yet supported)', (tester) async {
-      final message = eg.streamMessage(flags: [MessageFlag.starred]);
-      await setupToMessageActionSheet(tester, message: message, narrow: const StarredMessagesNarrow());
-      check(findQuoteAndReplyButton(tester)).isNull();
-    });
-  });
+        testWidgets('shows error when fails', (tester) async {
+          final message = eg.streamMessage(flags: [MessageFlag.read]);
+          await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
 
-  group('MarkAsUnread', () {
-    testWidgets('not visible if message is not read', (tester) async {
-      final unreadMessage = eg.streamMessage(flags: []);
-      await setupToMessageActionSheet(tester, message: unreadMessage, narrow: TopicNarrow.ofMessage(unreadMessage));
+          connection.prepare(exception: http.ClientException('Oops'));
+          final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
 
-      check(find.byIcon(Icons.mark_chat_unread_outlined).evaluate()).isEmpty();
+          await tester.ensureVisible(find.byIcon(Icons.mark_chat_unread_outlined, skipOffstage: false));
+          await tester.tap(find.byIcon(Icons.mark_chat_unread_outlined, skipOffstage: false));
+          await tester.pumpAndSettle();
+          checkErrorDialog(tester,
+            expectedTitle: zulipLocalizations.errorMarkAsUnreadFailedTitle,
+            expectedMessage: 'NetworkException: Oops (ClientException: Oops)');
+        });
+      });
     });
 
-    testWidgets('visible if message is read', (tester) async {
-      final readMessage = eg.streamMessage(flags: [MessageFlag.read]);
-      await setupToMessageActionSheet(tester, message: readMessage, narrow: TopicNarrow.ofMessage(readMessage));
+    group('CopyMessageTextButton', () {
+      setUp(() async {
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
+          SystemChannels.platform,
+          MockClipboard().handleMethodCall,
+        );
+      });
 
-      check(find.byIcon(Icons.mark_chat_unread_outlined).evaluate()).single;
-    });
+      Future<void> tapCopyMessageTextButton(WidgetTester tester) async {
+        await tester.ensureVisible(find.byIcon(ZulipIcons.copy, skipOffstage: false));
+        await tester.tap(find.byIcon(ZulipIcons.copy));
+        await tester.pump(); // [MenuItemButton.onPressed] called in a post-frame callback: flutter/flutter@e4a39fa2e
+      }
 
-    group('onPressed', () {
-      testWidgets('smoke test', (tester) async {
-        final message = eg.streamMessage(flags: [MessageFlag.read]);
+      testWidgets('success', (tester) async {
+        final message = eg.streamMessage();
         await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
 
-        connection.prepare(json: UpdateMessageFlagsForNarrowResult(
-          processedCount: 11, updatedCount: 3,
-          firstProcessedId: 1, lastProcessedId: 1980,
-          foundOldest: true, foundNewest: true).toJson());
-
-        await tester.ensureVisible(find.byIcon(Icons.mark_chat_unread_outlined, skipOffstage: false));
-        await tester.tap(find.byIcon(Icons.mark_chat_unread_outlined, skipOffstage: false));
-        await tester.pumpAndSettle();
-        check(connection.lastRequest).isA<http.Request>()
-          ..method.equals('POST')
-          ..url.path.equals('/api/v1/messages/flags/narrow')
-          ..bodyFields.deepEquals({
-              'anchor': '${message.id}',
-              'include_anchor': 'true',
-              'num_before': '0',
-              'num_after': '1000',
-              'narrow': jsonEncode(TopicNarrow.ofMessage(message).apiEncode()),
-              'op': 'remove',
-              'flag': 'read',
-            });
-      });
-
-      testWidgets('on topic move, acts on new topic', (tester) async {
-        final stream = eg.stream();
-        const topic = 'old topic';
-        final message = eg.streamMessage(flags: [MessageFlag.read],
-          stream: stream, topic: topic);
-        await setupToMessageActionSheet(tester, message: message,
-          narrow: TopicNarrow.ofMessage(message));
-
-        // Get the action sheet fully deployed while the old narrow applies.
-        // (This way we maximize the range of potential bugs this test can catch,
-        // by giving the code maximum opportunity to latch onto the old topic.)
-        await tester.pumpAndSettle();
-
-        final newStream = eg.stream();
-        const newTopic = 'other topic';
-        // This result isn't quite realistic for this request: it should get
-        // the updated channel/stream ID and topic, because we don't even
-        // start the request until after we get the move event.
-        // But constructing the right result is annoying at the moment, and
-        // it doesn't matter anyway: [MessageStoreImpl.reconcileMessages] will
-        // keep the version updated by the event.  If that somehow changes in
-        // some future refactor, it'll cause this test to fail.
-        connection.prepare(json: eg.newestGetMessagesResult(
-          foundOldest: true, messages: [message]).toJson());
-        await store.handleEvent(eg.updateMessageEventMoveFrom(
-          newStreamId: newStream.streamId, newTopic: newTopic,
-          propagateMode: PropagateMode.changeAll,
-          origMessages: [message]));
-
-        connection.prepare(json: UpdateMessageFlagsForNarrowResult(
-          processedCount: 11, updatedCount: 3,
-          firstProcessedId: 1, lastProcessedId: 1980,
-          foundOldest: true, foundNewest: true).toJson());
-        await tester.tap(find.byIcon(Icons.mark_chat_unread_outlined, skipOffstage: false));
-        await tester.pumpAndSettle();
-        check(connection.lastRequest).isA<http.Request>()
-          ..method.equals('POST')
-          ..url.path.equals('/api/v1/messages/flags/narrow')
-          ..bodyFields['narrow'].equals(
-              jsonEncode(TopicNarrow(newStream.streamId, newTopic).apiEncode()));
+        prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world');
+        await tapCopyMessageTextButton(tester);
+        await tester.pump(Duration.zero);
+        check(await Clipboard.getData('text/plain')).isNotNull().text.equals('Hello world');
       });
 
-      testWidgets('shows error when fails', (tester) async {
-        final message = eg.streamMessage(flags: [MessageFlag.read]);
+      testWidgets('can show snackbar on success', (tester) async {
+        // Regression test for: https://github.com/zulip/zulip-flutter/issues/732
+        testBinding.deviceInfoResult = const IosDeviceInfo(systemVersion: '16.0');
+
+        final message = eg.streamMessage();
         await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
 
-        connection.prepare(exception: http.ClientException('Oops'));
+        // Make the request take a bit of time to complete…
+        prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world',
+          delay: const Duration(milliseconds: 500));
+        await tapCopyMessageTextButton(tester);
+        // … and pump a frame to finish the NavigationState.pop animation…
+        await tester.pump(const Duration(milliseconds: 250));
+        // … before the request finishes.  This is the repro condition for #732.
+        await tester.pump(const Duration(milliseconds: 250));
+
+        final snackbar = tester.widget<SnackBar>(find.byType(SnackBar));
+        check(snackbar.behavior).equals(SnackBarBehavior.floating);
         final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
-
-        await tester.ensureVisible(find.byIcon(Icons.mark_chat_unread_outlined, skipOffstage: false));
-        await tester.tap(find.byIcon(Icons.mark_chat_unread_outlined, skipOffstage: false));
-        await tester.pumpAndSettle();
-        checkErrorDialog(tester,
-          expectedTitle: zulipLocalizations.errorMarkAsUnreadFailedTitle,
-          expectedMessage: 'NetworkException: Oops (ClientException: Oops)');
+        tester.widget(find.descendant(matchRoot: true,
+          of: find.byWidget(snackbar.content),
+          matching: find.text(zulipLocalizations.successMessageTextCopied)));
       });
-    });
-  });
-
-  group('CopyMessageTextButton', () {
-    setUp(() async {
-      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
-        SystemChannels.platform,
-        MockClipboard().handleMethodCall,
-      );
-    });
-
-    Future<void> tapCopyMessageTextButton(WidgetTester tester) async {
-      await tester.ensureVisible(find.byIcon(ZulipIcons.copy, skipOffstage: false));
-      await tester.tap(find.byIcon(ZulipIcons.copy));
-      await tester.pump(); // [MenuItemButton.onPressed] called in a post-frame callback: flutter/flutter@e4a39fa2e
-    }
-
-    testWidgets('success', (tester) async {
-      final message = eg.streamMessage();
-      await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
-
-      prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world');
-      await tapCopyMessageTextButton(tester);
-      await tester.pump(Duration.zero);
-      check(await Clipboard.getData('text/plain')).isNotNull().text.equals('Hello world');
-    });
-
-    testWidgets('can show snackbar on success', (tester) async {
-      // Regression test for: https://github.com/zulip/zulip-flutter/issues/732
-      testBinding.deviceInfoResult = const IosDeviceInfo(systemVersion: '16.0');
 
-      final message = eg.streamMessage();
-      await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
-
-      // Make the request take a bit of time to complete…
-      prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world',
-        delay: const Duration(milliseconds: 500));
-      await tapCopyMessageTextButton(tester);
-      // … and pump a frame to finish the NavigationState.pop animation…
-      await tester.pump(const Duration(milliseconds: 250));
-      // … before the request finishes.  This is the repro condition for #732.
-      await tester.pump(const Duration(milliseconds: 250));
-
-      final snackbar = tester.widget<SnackBar>(find.byType(SnackBar));
-      check(snackbar.behavior).equals(SnackBarBehavior.floating);
-      final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
-      tester.widget(find.descendant(matchRoot: true,
-        of: find.byWidget(snackbar.content),
-        matching: find.text(zulipLocalizations.successMessageTextCopied)));
-    });
-
-    testWidgets('request has an error', (tester) async {
-      final message = eg.streamMessage();
-      await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+      testWidgets('request has an error', (tester) async {
+        final message = eg.streamMessage();
+        await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
 
-      prepareRawContentResponseError();
-      await tapCopyMessageTextButton(tester);
-      await tester.pump(Duration.zero); // error arrives; error dialog shows
+        prepareRawContentResponseError();
+        await tapCopyMessageTextButton(tester);
+        await tester.pump(Duration.zero); // error arrives; error dialog shows
 
-      await tester.tap(find.byWidget(checkErrorDialog(tester,
-        expectedTitle: 'Copying failed',
-        expectedMessage: 'That message does not seem to exist.',
-      )));
-      check(await Clipboard.getData('text/plain')).isNull();
+        await tester.tap(find.byWidget(checkErrorDialog(tester,
+          expectedTitle: 'Copying failed',
+          expectedMessage: 'That message does not seem to exist.',
+        )));
+        check(await Clipboard.getData('text/plain')).isNull();
+      });
     });
-  });
 
-  group('CopyMessageLinkButton', () {
-    setUp(() async {
-      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
-        SystemChannels.platform,
-        MockClipboard().handleMethodCall,
-      );
-    });
+    group('CopyMessageLinkButton', () {
+      setUp(() async {
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
+          SystemChannels.platform,
+          MockClipboard().handleMethodCall,
+        );
+      });
 
-    Future<void> tapCopyMessageLinkButton(WidgetTester tester) async {
-      await tester.ensureVisible(find.byIcon(Icons.link, skipOffstage: false));
-      await tester.tap(find.byIcon(Icons.link));
-      await tester.pump(); // [MenuItemButton.onPressed] called in a post-frame callback: flutter/flutter@e4a39fa2e
-    }
+      Future<void> tapCopyMessageLinkButton(WidgetTester tester) async {
+        await tester.ensureVisible(find.byIcon(Icons.link, skipOffstage: false));
+        await tester.tap(find.byIcon(Icons.link));
+        await tester.pump(); // [MenuItemButton.onPressed] called in a post-frame callback: flutter/flutter@e4a39fa2e
+      }
 
-    testWidgets('copies message link to clipboard', (tester) async {
-      final message = eg.streamMessage();
-      final narrow = TopicNarrow.ofMessage(message);
-      await setupToMessageActionSheet(tester, message: message, narrow: narrow);
+      testWidgets('copies message link to clipboard', (tester) async {
+        final message = eg.streamMessage();
+        final narrow = TopicNarrow.ofMessage(message);
+        await setupToMessageActionSheet(tester, message: message, narrow: narrow);
 
-      await tapCopyMessageLinkButton(tester);
-      await tester.pump(Duration.zero);
-      final expectedLink = narrowLink(store, narrow, nearMessageId: message.id).toString();
-      check(await Clipboard.getData('text/plain')).isNotNull().text.equals(expectedLink);
+        await tapCopyMessageLinkButton(tester);
+        await tester.pump(Duration.zero);
+        final expectedLink = narrowLink(store, narrow, nearMessageId: message.id).toString();
+        check(await Clipboard.getData('text/plain')).isNotNull().text.equals(expectedLink);
+      });
     });
-  });
 
-  group('ShareButton', () {
-    // Tests should call this.
-    MockSharePlus setupMockSharePlus() {
-      final mock = MockSharePlus();
-      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
-        MethodChannelShare.channel,
-        mock.handleMethodCall,
-      );
-      return mock;
-    }
+    group('ShareButton', () {
+      // Tests should call this.
+      MockSharePlus setupMockSharePlus() {
+        final mock = MockSharePlus();
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
+          MethodChannelShare.channel,
+          mock.handleMethodCall,
+        );
+        return mock;
+      }
 
-    Future<void> tapShareButton(WidgetTester tester) async {
-      await tester.ensureVisible(find.byIcon(ZulipIcons.share, skipOffstage: false));
-      await tester.tap(find.byIcon(ZulipIcons.share));
-      await tester.pump(); // [MenuItemButton.onPressed] called in a post-frame callback: flutter/flutter@e4a39fa2e
-    }
+      Future<void> tapShareButton(WidgetTester tester) async {
+        await tester.ensureVisible(find.byIcon(ZulipIcons.share, skipOffstage: false));
+        await tester.tap(find.byIcon(ZulipIcons.share));
+        await tester.pump(); // [MenuItemButton.onPressed] called in a post-frame callback: flutter/flutter@e4a39fa2e
+      }
 
-    testWidgets('request succeeds; sharing succeeds', (tester) async {
-      final mockSharePlus = setupMockSharePlus();
-      final message = eg.streamMessage();
-      await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+      testWidgets('request succeeds; sharing succeeds', (tester) async {
+        final mockSharePlus = setupMockSharePlus();
+        final message = eg.streamMessage();
+        await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
 
-      prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world');
-      await tapShareButton(tester);
-      await tester.pump(Duration.zero);
-      check(mockSharePlus.sharedString).equals('Hello world');
-    });
+        prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world');
+        await tapShareButton(tester);
+        await tester.pump(Duration.zero);
+        check(mockSharePlus.sharedString).equals('Hello world');
+      });
 
-    testWidgets('request succeeds; sharing fails', (tester) async {
-      final mockSharePlus = setupMockSharePlus();
-      final message = eg.streamMessage();
-      await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+      testWidgets('request succeeds; sharing fails', (tester) async {
+        final mockSharePlus = setupMockSharePlus();
+        final message = eg.streamMessage();
+        await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
 
-      prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world');
-      mockSharePlus.resultString = 'dev.fluttercommunity.plus/share/unavailable';
-      await tapShareButton(tester);
-      await tester.pump(Duration.zero);
-      check(mockSharePlus.sharedString).equals('Hello world');
-      await tester.pump();
-      await tester.tap(find.byWidget(checkErrorDialog(tester,
-        expectedTitle: 'Sharing failed')));
-    });
+        prepareRawContentResponseSuccess(message: message, rawContent: 'Hello world');
+        mockSharePlus.resultString = 'dev.fluttercommunity.plus/share/unavailable';
+        await tapShareButton(tester);
+        await tester.pump(Duration.zero);
+        check(mockSharePlus.sharedString).equals('Hello world');
+        await tester.pump();
+        await tester.tap(find.byWidget(checkErrorDialog(tester,
+          expectedTitle: 'Sharing failed')));
+      });
 
-    testWidgets('request has an error', (tester) async {
-      final mockSharePlus = setupMockSharePlus();
-      final message = eg.streamMessage();
-      await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+      testWidgets('request has an error', (tester) async {
+        final mockSharePlus = setupMockSharePlus();
+        final message = eg.streamMessage();
+        await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
 
-      prepareRawContentResponseError();
-      await tapShareButton(tester);
-      await tester.pump(Duration.zero); // error arrives; error dialog shows
+        prepareRawContentResponseError();
+        await tapShareButton(tester);
+        await tester.pump(Duration.zero); // error arrives; error dialog shows
 
-      await tester.tap(find.byWidget(checkErrorDialog(tester,
-        expectedTitle: 'Sharing failed',
-        expectedMessage: 'That message does not seem to exist.',
-      )));
+        await tester.tap(find.byWidget(checkErrorDialog(tester,
+          expectedTitle: 'Sharing failed',
+          expectedMessage: 'That message does not seem to exist.',
+        )));
 
-      check(mockSharePlus.sharedString).isNull();
+        check(mockSharePlus.sharedString).isNull();
+      });
     });
-  });
 
-  group('MessageActionSheetCancelButton', () {
-    final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
+    group('MessageActionSheetCancelButton', () {
+      final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
 
-    void checkActionSheet(WidgetTester tester, {required bool isShown}) {
-      check(find.text(zulipLocalizations.actionSheetOptionStarMessage)
-        .evaluate().length).equals(isShown ? 1 : 0);
+      void checkActionSheet(WidgetTester tester, {required bool isShown}) {
+        check(find.text(zulipLocalizations.actionSheetOptionStarMessage)
+          .evaluate().length).equals(isShown ? 1 : 0);
 
-      final findCancelButton = find.text(zulipLocalizations.dialogCancel);
-      check(findCancelButton.evaluate().length).equals(isShown ? 1 : 0);
-    }
+        final findCancelButton = find.text(zulipLocalizations.dialogCancel);
+        check(findCancelButton.evaluate().length).equals(isShown ? 1 : 0);
+      }
 
-    testWidgets('pressing the button dismisses the action sheet', (tester) async {
-      final message = eg.streamMessage();
-      await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
-      checkActionSheet(tester, isShown: true);
+      testWidgets('pressing the button dismisses the action sheet', (tester) async {
+        final message = eg.streamMessage();
+        await setupToMessageActionSheet(tester, message: message, narrow: TopicNarrow.ofMessage(message));
+        checkActionSheet(tester, isShown: true);
 
-      final findCancelButton = find.text(zulipLocalizations.dialogCancel);
-      await tester.tap(findCancelButton);
-      await tester.pumpAndSettle();
-      checkActionSheet(tester, isShown: false);
+        final findCancelButton = find.text(zulipLocalizations.dialogCancel);
+        await tester.tap(findCancelButton);
+        await tester.pumpAndSettle();
+        checkActionSheet(tester, isShown: false);
+      });
     });
   });
 }
diff --git a/test/widgets/actions_test.dart b/test/widgets/actions_test.dart
index 4a4698a175..5a957c44e0 100644
--- a/test/widgets/actions_test.dart
+++ b/test/widgets/actions_test.dart
@@ -42,6 +42,7 @@ void main() {
   Future<void> prepare(WidgetTester tester, {
     UnreadMessagesSnapshot? unreadMsgs,
     String? ackedPushToken = '123',
+    bool skipAssertAccountExists = false,
   }) async {
     addTearDown(testBinding.reset);
     final selfAccount = eg.selfAccount.copyWith(ackedPushToken: Value(ackedPushToken));
@@ -50,7 +51,9 @@ void main() {
     store = await testBinding.globalStore.perAccount(selfAccount.id);
     connection = store.connection as FakeApiConnection;
 
-    await tester.pumpWidget(TestZulipApp(accountId: selfAccount.id,
+    await tester.pumpWidget(TestZulipApp(
+      accountId: selfAccount.id,
+      skipAssertAccountExists: skipAssertAccountExists,
       child: const Scaffold(body: Placeholder())));
     await tester.pump();
     context = tester.element(find.byType(Placeholder));
@@ -99,7 +102,7 @@ void main() {
 
   group('logOutAccount', () {
     testWidgets('smoke', (tester) async {
-      await prepare(tester);
+      await prepare(tester, skipAssertAccountExists: true);
       check(testBinding.globalStore).accountIds.single.equals(eg.selfAccount.id);
       const unregisterDelay = Duration(seconds: 5);
       assert(unregisterDelay > TestGlobalStore.removeAccountDuration);
@@ -124,7 +127,7 @@ void main() {
     });
 
     testWidgets('unregister request has an error', (tester) async {
-      await prepare(tester);
+      await prepare(tester, skipAssertAccountExists: true);
       check(testBinding.globalStore).accountIds.single.equals(eg.selfAccount.id);
       const unregisterDelay = Duration(seconds: 5);
       assert(unregisterDelay > TestGlobalStore.removeAccountDuration);
diff --git a/test/widgets/app_bar_test.dart b/test/widgets/app_bar_test.dart
index 3685eb4ae0..099471d4f7 100644
--- a/test/widgets/app_bar_test.dart
+++ b/test/widgets/app_bar_test.dart
@@ -1,5 +1,7 @@
 import 'package:checks/checks.dart';
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter_checks/flutter_checks.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:zulip/widgets/app_bar.dart';
 import 'package:zulip/widgets/profile.dart';
@@ -35,4 +37,124 @@ void main() {
     check(tester.getRect(find.byType(ZulipAppBar))).equals(rectBefore);
     check(finder.evaluate()).single;
   });
+
+  group("buildTitle's willCenterTitle agrees with Material AppBar", () {
+    /// Build an [AppBar]; inspect and return whether it decided to center.
+    Future<bool> material(WidgetTester tester, {
+      required bool? paramValue,
+      required bool? themeValue,
+      required List<Widget>? actions,
+    }) async {
+      testBinding.reset();
+
+      final themeData = ThemeData(appBarTheme: AppBarTheme(centerTitle: themeValue));
+      final widget = TestZulipApp(
+        child: Theme(data: themeData,
+          child: AppBar(
+            centerTitle: paramValue,
+            actions: actions,
+            title: const Text('a'))));
+
+      await tester.pumpWidget(widget);
+      await tester.pump();
+
+      // test assumes LTR text direction
+      check(tester.platformDispatcher.locale).equals(const Locale('en', 'US'));
+      assert(actions == null || actions.isNotEmpty);
+      final titleAreaRightEdgeOffset = actions == null
+        ? (tester.view.physicalSize / tester.view.devicePixelRatio).width
+        : tester.getTopLeft(find.byWidget(actions.first)).dx;
+      final titlePosition = tester.getTopLeft(find.text('a')).dx;
+      final isCentered = titlePosition > ((1 / 3) * titleAreaRightEdgeOffset);
+      check(titlePosition).isLessThan((2 / 3) * titleAreaRightEdgeOffset);
+
+      return isCentered;
+    }
+
+    /// Build a [ZulipAppBar]; return willCenterTitle from the buildTitle call.
+    Future<bool> ours(WidgetTester tester, {
+      required bool? paramValue,
+      required bool? themeValue,
+      required List<Widget>? actions,
+    }) async {
+      testBinding.reset();
+      await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot());
+
+      bool? result;
+
+      final widget = TestZulipApp(
+        // ZulipAppBar expects a per-account context (for the loading indicator)
+        accountId: eg.selfAccount.id,
+        child: Builder(builder: (context) => Theme(
+          data: Theme.of(context).copyWith(appBarTheme: AppBarTheme(centerTitle: themeValue)),
+          child: ZulipAppBar(
+            centerTitle: paramValue,
+            actions: actions,
+            buildTitle: (willCenterTitle) {
+              result = willCenterTitle;
+              return const Text('a');
+            }))));
+
+      await tester.pumpWidget(widget);
+      await tester.pump(); // global store
+      await tester.pump(); // per-account store
+      check(find.widgetWithText(ZulipAppBar, 'a')).findsOne();
+
+      check(result).isNotNull();
+      return result!;
+    }
+
+    void doTest(String description, bool expectedWillCenter, {
+      bool? paramValue,
+      bool? themeValue,
+      TargetPlatform? platform,
+      List<Widget>? actions,
+    }) {
+      testWidgets(description, (tester) async {
+        addTearDown(testBinding.reset);
+        debugDefaultTargetPlatformOverride = platform;
+
+        check(
+          await ours(tester, paramValue: paramValue, themeValue: themeValue, actions: actions)
+        )..equals(
+          await material(tester, paramValue: paramValue, themeValue: themeValue, actions: actions)
+        )..equals(expectedWillCenter);
+
+        // TODO(upstream) Do this in an addTearDown, once we can:
+        //   https://github.com/flutter/flutter/issues/123189
+        debugDefaultTargetPlatformOverride = null;
+      });
+    }
+
+    const iOS = TargetPlatform.iOS;
+    const android = TargetPlatform.android;
+
+    Widget button() => IconButton(icon: const Icon(Icons.add), onPressed: () {});
+    final oneButton =    [button()];
+    final twoButtons =   [button(), button()];
+    final threeButtons = [button(), button(), button()];
+
+    doTest('ios',     true,  platform: iOS);
+    doTest('android', false, platform: android);
+
+    doTest('ios, theme false',    false, platform: iOS,     themeValue: false);
+    doTest('android, theme true', true,  platform: android, themeValue: true);
+
+    doTest('ios, param false',    false, platform: iOS,     paramValue: false);
+    doTest('android, param true', true,  platform: android, paramValue: true);
+
+    doTest('ios, theme true, param false', false,     platform: iOS,     themeValue: true,  paramValue: false);
+    doTest('ios, theme false, param true', true,      platform: iOS,     themeValue: false, paramValue: true);
+
+    doTest('android, theme true, param false', false, platform: android, themeValue: true,  paramValue: false);
+    doTest('android, theme false, param true', true,  platform: android, themeValue: false, paramValue: true);
+
+    doTest('ios, no actions',    true,  platform: iOS, actions: null);
+    doTest('ios, one action',    true,  platform: iOS, actions: oneButton);
+    doTest('ios, two actions' ,  false, platform: iOS, actions: twoButtons);
+    doTest('ios, three actions', false, platform: iOS, actions: threeButtons);
+
+    doTest('ios, two actions but param true', true, platform: iOS, paramValue: true, actions: twoButtons);
+    doTest('ios, two actions but theme true', true, platform: iOS, themeValue: true, actions: twoButtons);
+  });
 }
diff --git a/test/widgets/app_test.dart b/test/widgets/app_test.dart
index 8c992533ee..af386bfdf1 100644
--- a/test/widgets/app_test.dart
+++ b/test/widgets/app_test.dart
@@ -280,14 +280,14 @@ void main() {
       check(ZulipApp.ready).value.isFalse();
       await tester.pump();
       check(findSnackBarByText(message).evaluate()).isEmpty();
-      check(find.byType(AlertDialog).evaluate()).isEmpty();
+      checkNoErrorDialog(tester);
 
       check(ZulipApp.ready).value.isTrue();
       // After app startup, reportErrorToUserBriefly displays a SnackBar.
       reportErrorToUserBriefly(message, details: details);
       await tester.pumpAndSettle();
       check(findSnackBarByText(message).evaluate()).single;
-      check(find.byType(AlertDialog).evaluate()).isEmpty();
+      checkNoErrorDialog(tester);
 
       // Open the error details dialog.
       await tester.tap(find.text('Details'));
diff --git a/test/widgets/autocomplete_test.dart b/test/widgets/autocomplete_test.dart
index 24ae2dba83..3f3c32bd59 100644
--- a/test/widgets/autocomplete_test.dart
+++ b/test/widgets/autocomplete_test.dart
@@ -13,10 +13,13 @@ import 'package:zulip/model/localizations.dart';
 import 'package:zulip/model/narrow.dart';
 import 'package:zulip/model/store.dart';
 import 'package:zulip/model/typing_status.dart';
+import 'package:zulip/widgets/compose_box.dart';
+import 'package:zulip/widgets/icons.dart';
 import 'package:zulip/widgets/message_list.dart';
 
 import '../api/fake_api.dart';
 import '../example_data.dart' as eg;
+import '../flutter_checks.dart';
 import '../model/binding.dart';
 import '../model/test_store.dart';
 import '../test_images.dart';
@@ -33,7 +36,9 @@ import 'test_app.dart';
 /// before the end of the test.
 Future<Finder> setupToComposeInput(WidgetTester tester, {
   List<User> users = const [],
+  Narrow? narrow,
 }) async {
+  assert(narrow is ChannelNarrow? || narrow is SendableNarrow?);
   TypingNotifier.debugEnable = false;
   addTearDown(TypingNotifier.debugReset);
 
@@ -44,8 +49,24 @@ Future<Finder> setupToComposeInput(WidgetTester tester, {
   await store.addUsers(users);
   final connection = store.connection as FakeApiConnection;
 
+  narrow ??= DmNarrow(
+    allRecipientIds: [eg.selfUser.userId, eg.otherUser.userId],
+    selfUserId: eg.selfUser.userId);
   // prepare message list data
-  final message = eg.dmMessage(from: eg.selfUser, to: [eg.otherUser]);
+  final Message message;
+  switch(narrow) {
+    case DmNarrow():
+      message = eg.dmMessage(from: eg.selfUser, to: [eg.otherUser]);
+    case ChannelNarrow(:final streamId):
+      final stream = eg.stream(streamId: streamId);
+      message = eg.streamMessage(stream: stream);
+      await store.addStream(stream);
+    case TopicNarrow(:final streamId, :final topic):
+      final stream = eg.stream(streamId: streamId);
+      message = eg.streamMessage(stream: stream, topic: topic.apiName);
+      await store.addStream(stream);
+    default: throw StateError('unexpected narrow type');
+  }
   connection.prepare(json: GetMessagesResult(
     anchor: message.id,
     foundNewest: true,
@@ -58,15 +79,13 @@ Future<Finder> setupToComposeInput(WidgetTester tester, {
   prepareBoringImageHttpClient();
 
   await tester.pumpWidget(TestZulipApp(accountId: eg.selfAccount.id,
-    child: MessageListPage(initNarrow: DmNarrow(
-      allRecipientIds: [eg.selfUser.userId, eg.otherUser.userId],
-      selfUserId: eg.selfUser.userId))));
+    child: MessageListPage(initNarrow: narrow)));
 
   // global store, per-account store, and message list get loaded
   await tester.pumpAndSettle();
 
-  // (hint text of compose input in a 1:1 DM)
-  final finder = find.widgetWithText(TextField, 'Message @${eg.otherUser.fullName}');
+  final finder = find.byWidgetPredicate((widget) => widget is TextField
+    && widget.controller is ComposeContentController);
   check(finder.evaluate()).isNotEmpty();
   return finder;
 }
@@ -133,7 +152,7 @@ void main() {
       check(avatarFinder.evaluate().length).equals(expected ? 1 : 0);
     }
 
-    testWidgets('options appear, disappear, and change correctly', (tester) async {
+    testWidgets('user options appear, disappear, and change correctly', (tester) async {
       final user1 = eg.user(userId: 1, fullName: 'User One', avatarUrl: 'user1.png');
       final user2 = eg.user(userId: 2, fullName: 'User Two', avatarUrl: 'user2.png');
       final user3 = eg.user(userId: 3, fullName: 'User Three', avatarUrl: 'user3.png');
@@ -155,7 +174,7 @@ void main() {
       await tester.tap(find.text('User Three'));
       await tester.pump();
       check(tester.widget<TextField>(composeInputFinder).controller!.text)
-        .contains(mention(user3, users: store.users));
+        .contains(userMention(user3, users: store.users));
       checkUserShown(user1, store, expected: false);
       checkUserShown(user2, store, expected: false);
       checkUserShown(user3, store, expected: false);
@@ -177,6 +196,46 @@ void main() {
 
       debugNetworkImageHttpClientProvider = null;
     });
+
+    void checkWildcardShown(WildcardMentionOption wildcard, {required bool expected}) {
+      final richTextFinder = find.textContaining(wildcard.canonicalString, findRichText: true);
+      final iconFinder = find.byIcon(ZulipIcons.three_person);
+      final wildcardItemFinder = find.ancestor(of: richTextFinder,
+        matching: find.ancestor(of: iconFinder, matching: find.byType(Row)));
+      check(wildcardItemFinder.evaluate().length).equals(expected ? 1 : 0);
+    }
+
+    testWidgets('wildcard options appear, disappear, and change correctly', (tester) async {
+      final composeInputFinder = await setupToComposeInput(tester,
+        narrow: const ChannelNarrow(1));
+      final store = await testBinding.globalStore.perAccount(eg.selfAccount.id);
+
+      // Options are filtered correctly for query
+      // TODO(#226): Remove this extra edit when this bug is fixed.
+      await tester.enterText(composeInputFinder, 'hello @');
+      await tester.enterText(composeInputFinder, 'hello @c');
+      await tester.pumpAndSettle(); // async computation; options appear
+
+      checkWildcardShown(WildcardMentionOption.channel, expected: true);
+      checkWildcardShown(WildcardMentionOption.topic, expected: true);
+      checkWildcardShown(WildcardMentionOption.all, expected: false);
+      checkWildcardShown(WildcardMentionOption.everyone, expected: false);
+      checkWildcardShown(WildcardMentionOption.stream, expected: false);
+
+      // Finishing autocomplete updates compose box; causes options to disappear
+      await tester.tap(find.textContaining(WildcardMentionOption.channel.canonicalString,
+        findRichText: true));
+      await tester.pump();
+      check(tester.widget<TextField>(composeInputFinder).controller!.text)
+        .contains(wildcardMention(WildcardMentionOption.channel, store: store));
+      checkWildcardShown(WildcardMentionOption.channel, expected: false);
+      checkWildcardShown(WildcardMentionOption.topic, expected: false);
+      checkWildcardShown(WildcardMentionOption.all, expected: false);
+      checkWildcardShown(WildcardMentionOption.everyone, expected: false);
+      checkWildcardShown(WildcardMentionOption.stream, expected: false);
+
+      debugNetworkImageHttpClientProvider = null;
+    });
   });
 
   group('emoji', () {
@@ -224,6 +283,9 @@ void main() {
       await tester.enterText(composeInputFinder, 'hi :');
       await tester.enterText(composeInputFinder, 'hi :z');
       await tester.pump();
+      // Add an extra pump to account for any potential frame delays introduced
+      // by the post frame callback in RawAutocomplete's implementation.
+      await tester.pump();
       checkEmojiShown(expected: true, zzzOption);
       checkEmojiShown(expected: true, buzzingOption);
       checkEmojiShown(expected: true, zulipOption);
@@ -273,7 +335,7 @@ void main() {
 
   group('TopicAutocomplete', () {
     void checkTopicShown(GetStreamTopicsEntry topic, PerAccountStore store, {required bool expected}) {
-      check(find.text(topic.name).evaluate().length).equals(expected ? 1 : 0);
+      check(find.text(topic.name.displayName).evaluate().length).equals(expected ? 1 : 0);
     }
 
     testWidgets('options appear, disappear, and change correctly', (WidgetTester tester) async {
@@ -298,7 +360,7 @@ void main() {
       await tester.tap(find.text('Topic three'));
       await tester.pumpAndSettle();
       check(tester.widget<TextField>(topicInputFinder).controller!.text)
-        .equals(topic3.name);
+        .equals(topic3.name.displayName);
       checkTopicShown(topic1, store, expected: false);
       checkTopicShown(topic2, store, expected: false);
       checkTopicShown(topic3, store, expected: true); // shown in `_TopicInput` once
@@ -309,5 +371,40 @@ void main() {
       await tester.pumpAndSettle();
       checkTopicShown(topic2, store, expected: true);
     });
+
+    testWidgets('text selection is reset on choosing an option', (tester) async {
+      // TODO test also that composing region gets reset.
+      //   (Just adding it to the updateEditingValue call below doesn't seem
+      //   to suffice to set it up; the controller value after the pump still
+      //   has empty composing region, so there's nothing to check after tap.)
+
+      final topic = eg.getStreamTopicsEntry(name: 'some topic');
+      final topicInputFinder = await setupToTopicInput(tester, topics: [topic]);
+      final controller = tester.widget<TextField>(topicInputFinder).controller!;
+
+      await tester.enterText(topicInputFinder, 'so');
+      await tester.enterText(topicInputFinder, 'some');
+      tester.testTextInput.updateEditingValue(const TextEditingValue(
+        text: 'some',
+        selection: TextSelection(baseOffset: 1, extentOffset: 3)));
+      await tester.pump();
+      // Add an extra pump to account for any potential frame delays introduced
+      // by the post frame callback in RawAutocomplete's implementation.
+      await tester.pump();
+
+      check(controller.value)
+        ..text.equals('some')
+        ..selection.equals(
+            const TextSelection(baseOffset: 1, extentOffset: 3));
+
+      await tester.tap(find.text('some topic'));
+      await tester.pump();
+      check(controller.value)
+        ..text.equals('some topic')
+        ..selection.equals(
+            const TextSelection.collapsed(offset: 'some topic'.length));
+
+      await tester.pump(Duration.zero);
+    });
   });
 }
diff --git a/test/widgets/compose_box_test.dart b/test/widgets/compose_box_test.dart
index 077134e7d1..f1eb9bb3ba 100644
--- a/test/widgets/compose_box_test.dart
+++ b/test/widgets/compose_box_test.dart
@@ -41,15 +41,12 @@ void main() {
   late FakeApiConnection connection;
   late ComposeBoxController? controller;
 
-  final contentInputFinder = find.byWidgetPredicate(
-    (widget) => widget is TextField && widget.controller is ComposeContentController);
-
   Future<void> prepareComposeBox(WidgetTester tester, {
     required Narrow narrow,
     User? selfUser,
-    int? realmWaitingPeriodThreshold,
-    List<User> users = const [],
+    List<User> otherUsers = const [],
     List<ZulipStream> streams = const [],
+    bool? mandatoryTopics,
   }) async {
     if (narrow case ChannelNarrow(:var streamId) || TopicNarrow(: var streamId)) {
       assert(streams.any((stream) => stream.streamId == streamId),
@@ -59,11 +56,12 @@ void main() {
     selfUser ??= eg.selfUser;
     final selfAccount = eg.account(user: selfUser);
     await testBinding.globalStore.add(selfAccount, eg.initialSnapshot(
-      realmWaitingPeriodThreshold: realmWaitingPeriodThreshold));
+      realmMandatoryTopics: mandatoryTopics,
+    ));
 
     store = await testBinding.globalStore.perAccount(selfAccount.id);
 
-    await store.addUsers([selfUser, ...users]);
+    await store.addUsers([selfUser, ...otherUsers]);
     await store.addStreams(streams);
     connection = store.connection as FakeApiConnection;
 
@@ -80,6 +78,7 @@ void main() {
     controller = tester.state<ComposeBoxState>(find.byType(ComposeBox)).controller;
   }
 
+  /// Set the topic input's text to [topic], using [WidgetTester.enterText].
   Future<void> enterTopic(WidgetTester tester, {
     required ChannelNarrow narrow,
     required String topic,
@@ -95,6 +94,32 @@ void main() {
       ..url.path.equals('/api/v1/users/me/${narrow.streamId}/topics');
   }
 
+  /// A [Finder] for the content input.
+  ///
+  /// To enter some text, use [enterContent].
+  final contentInputFinder = find.byWidgetPredicate(
+    (widget) => widget is TextField && widget.controller is ComposeContentController);
+
+  /// Set the content input's text to [content], using [WidgetTester.enterText].
+  Future<void> enterContent(WidgetTester tester, String content) async {
+    await tester.enterText(contentInputFinder, content);
+  }
+
+  Future<void> tapSendButton(WidgetTester tester) async {
+    connection.prepare(json: SendMessageResult(id: 123).toJson());
+    await tester.tap(find.byIcon(ZulipIcons.send));
+    await tester.pump(Duration.zero);
+  }
+
+  group('ComposeBoxTheme', () {
+    test('lerp light to dark, no crash', () {
+      final a = ComposeBoxTheme.light;
+      final b = ComposeBoxTheme.dark;
+
+      check(() => a.lerp(b, 0.5)).returnsNormally();
+    });
+  });
+
   group('ComposeContentController', () {
     group('insertPadded', () {
       // Like `parseMarkedText` in test/model/autocomplete_test.dart,
@@ -197,6 +222,102 @@ void main() {
     });
   });
 
+  group('length validation', () {
+    final channel = eg.stream();
+
+    /// String where there are [n] Unicode code points,
+    /// >[n] UTF-16 code units, and <[n] "characters" a.k.a. grapheme clusters.
+    String makeStringWithCodePoints(int n) {
+      assert(n >= 5);
+      const graphemeCluster = '👨‍👩‍👦';
+      assert(graphemeCluster.runes.length == 5);
+      assert(graphemeCluster.length == 8);
+      assert(graphemeCluster.characters.length == 1);
+
+      final result =
+        graphemeCluster * (n ~/ 5)
+        + 'a' * (n % 5);
+      assert(result.runes.length == n);
+
+      return result;
+    }
+
+    group('content', () {
+      Future<void> prepareWithContent(WidgetTester tester, String content) async {
+        TypingNotifier.debugEnable = false;
+        addTearDown(TypingNotifier.debugReset);
+
+        final narrow = ChannelNarrow(channel.streamId);
+        await prepareComposeBox(tester, narrow: narrow, streams: [channel]);
+        await enterTopic(tester, narrow: narrow, topic: 'some topic');
+        await enterContent(tester, content);
+      }
+
+      Future<void> checkErrorResponse(WidgetTester tester) async {
+        await tester.tap(find.byWidget(checkErrorDialog(tester,
+          expectedTitle: 'Message not sent',
+          expectedMessage: 'Message length shouldn\'t be greater than 10000 characters.')));
+      }
+
+      testWidgets('too-long content is rejected', (tester) async {
+        await prepareWithContent(tester,
+          makeStringWithCodePoints(kMaxMessageLengthCodePoints + 1));
+        await tapSendButton(tester);
+        await checkErrorResponse(tester);
+      });
+
+      testWidgets('max-length content not rejected', (tester) async {
+        await prepareWithContent(tester,
+          makeStringWithCodePoints(kMaxMessageLengthCodePoints));
+        await tapSendButton(tester);
+        checkNoErrorDialog(tester);
+      });
+
+      testWidgets('code points not counted unnecessarily', (tester) async {
+        await prepareWithContent(tester, 'a' * kMaxMessageLengthCodePoints);
+        check(controller!.content.debugLengthUnicodeCodePointsIfLong).isNull();
+      });
+    });
+
+    group('topic', () {
+      Future<void> prepareWithTopic(WidgetTester tester, String topic) async {
+        TypingNotifier.debugEnable = false;
+        addTearDown(TypingNotifier.debugReset);
+
+        final narrow = ChannelNarrow(channel.streamId);
+        await prepareComposeBox(tester, narrow: narrow, streams: [channel]);
+        await enterTopic(tester, narrow: narrow, topic: topic);
+        await enterContent(tester, 'some content');
+      }
+
+      Future<void> checkErrorResponse(WidgetTester tester) async {
+        await tester.tap(find.byWidget(checkErrorDialog(tester,
+          expectedTitle: 'Message not sent',
+          expectedMessage: 'Topic length shouldn\'t be greater than 60 characters.')));
+      }
+
+      testWidgets('too-long topic is rejected', (tester) async {
+        await prepareWithTopic(tester,
+          makeStringWithCodePoints(kMaxTopicLengthCodePoints + 1));
+        await tapSendButton(tester);
+        await checkErrorResponse(tester);
+      });
+
+      testWidgets('max-length topic not rejected', (tester) async {
+        await prepareWithTopic(tester,
+          makeStringWithCodePoints(kMaxTopicLengthCodePoints));
+        await tapSendButton(tester);
+        checkNoErrorDialog(tester);
+      });
+
+      testWidgets('code points not counted unnecessarily', (tester) async {
+        await prepareWithTopic(tester, 'a' * kMaxTopicLengthCodePoints);
+        check((controller as StreamComposeBoxController)
+          .topic.debugLengthUnicodeCodePointsIfLong).isNull();
+      });
+    });
+  });
+
   group('ComposeBox textCapitalization', () {
     void checkComposeBoxTextFields(WidgetTester tester, {
       required bool expectTopicTextField,
@@ -230,21 +351,21 @@ void main() {
     testWidgets('_FixedDestinationComposeBox', (tester) async {
       final channel = eg.stream();
       await prepareComposeBox(tester,
-        narrow: TopicNarrow(channel.streamId, 'topic'), streams: [channel]);
+        narrow: eg.topicNarrow(channel.streamId, 'topic'), streams: [channel]);
       checkComposeBoxTextFields(tester, expectTopicTextField: false);
     });
   });
 
   group('ComposeBox typing notices', () {
     final channel = eg.stream();
-    final narrow = TopicNarrow(channel.streamId, 'some topic');
+    final narrow = eg.topicNarrow(channel.streamId, 'some topic');
 
     void checkTypingRequest(TypingOp op, SendableNarrow narrow) =>
       checkSetTypingStatusRequests(connection.takeRequests(), [(op, narrow)]);
 
     Future<void> checkStartTyping(WidgetTester tester, SendableNarrow narrow) async {
       connection.prepare(json: {});
-      await tester.enterText(contentInputFinder, 'hello world');
+      await enterContent(tester, 'hello world');
       checkTypingRequest(TypingOp.start, narrow);
     }
 
@@ -272,9 +393,9 @@ void main() {
 
     testWidgets('smoke ChannelNarrow', (tester) async {
       final narrow = ChannelNarrow(channel.streamId);
-      final destinationNarrow = TopicNarrow(narrow.streamId, 'test topic');
+      final destinationNarrow = eg.topicNarrow(narrow.streamId, 'test topic');
       await prepareComposeBox(tester, narrow: narrow, streams: [channel]);
-      await enterTopic(tester, narrow: narrow, topic: destinationNarrow.topic);
+      await enterTopic(tester, narrow: narrow, topic: 'test topic');
 
       await checkStartTyping(tester, destinationNarrow);
 
@@ -289,7 +410,7 @@ void main() {
       await checkStartTyping(tester, narrow);
 
       connection.prepare(json: {});
-      await tester.enterText(contentInputFinder, '');
+      await enterContent(tester, '');
       checkTypingRequest(TypingOp.stop, narrow);
     });
 
@@ -339,9 +460,9 @@ void main() {
 
     testWidgets('for content input, unfocusing sends a "typing stopped" notice', (tester) async {
       final narrow = ChannelNarrow(channel.streamId);
-      final destinationNarrow = TopicNarrow(narrow.streamId, 'test topic');
+      final destinationNarrow = eg.topicNarrow(narrow.streamId, 'test topic');
       await prepareComposeBox(tester, narrow: narrow, streams: [channel]);
-      await enterTopic(tester, narrow: narrow, topic: destinationNarrow.topic);
+      await enterTopic(tester, narrow: narrow, topic: 'test topic');
 
       await checkStartTyping(tester, destinationNarrow);
 
@@ -402,10 +523,10 @@ void main() {
       addTearDown(TypingNotifier.debugReset);
 
       final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
-      await prepareComposeBox(tester, narrow: const TopicNarrow(123, 'some topic'),
+      await prepareComposeBox(tester, narrow: eg.topicNarrow(123, 'some topic'),
         streams: [eg.stream(streamId: 123)]);
 
-      await tester.enterText(contentInputFinder, 'hello world');
+      await enterContent(tester, 'hello world');
 
       prepareResponse(456);
       await tester.tap(find.byTooltip(zulipLocalizations.composeBoxSendTooltip));
@@ -427,8 +548,7 @@ void main() {
       await setupAndTapSend(tester, prepareResponse: (int messageId) {
         connection.prepare(json: SendMessageResult(id: messageId).toJson());
       });
-      final errorDialogs = tester.widgetList(find.byType(AlertDialog));
-      check(errorDialogs).isEmpty();
+      checkNoErrorDialog(tester);
     });
 
     testWidgets('ZulipApiException', (tester) async {
@@ -450,6 +570,60 @@ void main() {
     });
   });
 
+  group('sending to empty topic', () {
+    late ZulipStream channel;
+
+    Future<void> setupAndTapSend(WidgetTester tester, {
+      required String topicInputText,
+      required bool mandatoryTopics,
+    }) async {
+      TypingNotifier.debugEnable = false;
+      addTearDown(TypingNotifier.debugReset);
+
+      channel = eg.stream();
+      final narrow = ChannelNarrow(channel.streamId);
+      await prepareComposeBox(tester,
+        narrow: narrow, streams: [channel],
+        mandatoryTopics: mandatoryTopics);
+
+      await enterTopic(tester, narrow: narrow, topic: topicInputText);
+      await tester.enterText(contentInputFinder, 'test content');
+      await tester.tap(find.byIcon(ZulipIcons.send));
+      await tester.pump();
+    }
+
+    void checkMessageNotSent(WidgetTester tester) {
+      check(connection.takeRequests()).isEmpty();
+      checkErrorDialog(tester,
+        expectedTitle: 'Message not sent',
+        expectedMessage: 'Topics are required in this organization.');
+    }
+
+    testWidgets('empty topic -> "(no topic)"', (tester) async {
+      await setupAndTapSend(tester,
+        topicInputText: '',
+        mandatoryTopics: false);
+      check(connection.lastRequest).isA<http.Request>()
+        ..method.equals('POST')
+        ..url.path.equals('/api/v1/messages')
+        ..bodyFields['topic'].equals('(no topic)');
+    });
+
+    testWidgets('if topics are mandatory, reject empty topic', (tester) async {
+      await setupAndTapSend(tester,
+        topicInputText: '',
+        mandatoryTopics: true);
+      checkMessageNotSent(tester);
+    });
+
+    testWidgets('if topics are mandatory, reject "(no topic)"', (tester) async {
+      await setupAndTapSend(tester,
+        topicInputText: '(no topic)',
+        mandatoryTopics: true);
+      checkMessageNotSent(tester);
+    });
+  });
+
   group('uploads', () {
     void checkAppearsLoading(WidgetTester tester, bool expected) {
       final sendButtonElement = tester.element(find.ancestor(
@@ -497,8 +671,7 @@ void main() {
         check(call.allowMultiple).equals(true);
         check(call.type).equals(FileType.media);
 
-        final errorDialogs = tester.widgetList(find.byType(AlertDialog));
-        check(errorDialogs).isEmpty();
+        checkNoErrorDialog(tester);
 
         check(controller!.content.text)
           .equals('see image: [Uploading image.jpg…]()\n\n');
@@ -557,8 +730,7 @@ void main() {
         check(call.source).equals(ImageSource.camera);
         check(call.requestFullMetadata).equals(false);
 
-        final errorDialogs = tester.widgetList(find.byType(AlertDialog));
-        check(errorDialogs).isEmpty();
+        checkNoErrorDialog(tester);
 
         check(controller!.content.text)
           .equals('see image: [Uploading image.jpg…]()\n\n');
@@ -640,7 +812,7 @@ void main() {
         testWidgets('compose box replaced with a banner', (tester) async {
           final deactivatedUser = eg.user(isActive: false);
           await prepareComposeBox(tester, narrow: dmNarrowWith(deactivatedUser),
-            users: [deactivatedUser]);
+            otherUsers: [deactivatedUser]);
           checkComposeBox(isShown: false);
         });
 
@@ -648,7 +820,7 @@ void main() {
             'compose box is replaced with a banner', (tester) async {
           final activeUser = eg.user(isActive: true);
           await prepareComposeBox(tester, narrow: dmNarrowWith(activeUser),
-            users: [activeUser]);
+            otherUsers: [activeUser]);
           checkComposeBox(isShown: true);
 
           await changeUserStatus(tester, user: activeUser, isActive: false);
@@ -659,7 +831,7 @@ void main() {
             'banner is replaced with the compose box', (tester) async {
           final deactivatedUser = eg.user(isActive: false);
           await prepareComposeBox(tester, narrow: dmNarrowWith(deactivatedUser),
-            users: [deactivatedUser]);
+            otherUsers: [deactivatedUser]);
           checkComposeBox(isShown: false);
 
           await changeUserStatus(tester, user: deactivatedUser, isActive: true);
@@ -671,7 +843,7 @@ void main() {
         testWidgets('compose box replaced with a banner', (tester) async {
           final deactivatedUsers = [eg.user(isActive: false), eg.user(isActive: false)];
           await prepareComposeBox(tester, narrow: groupDmNarrowWith(deactivatedUsers),
-            users: deactivatedUsers);
+            otherUsers: deactivatedUsers);
           checkComposeBox(isShown: false);
         });
 
@@ -679,7 +851,7 @@ void main() {
             'compose box is replaced with a banner', (tester) async {
           final activeUsers = [eg.user(isActive: true), eg.user(isActive: true)];
           await prepareComposeBox(tester, narrow: groupDmNarrowWith(activeUsers),
-            users: activeUsers);
+            otherUsers: activeUsers);
           checkComposeBox(isShown: true);
 
           await changeUserStatus(tester, user: activeUsers[0], isActive: false);
@@ -690,7 +862,7 @@ void main() {
             'banner is replaced with the compose box', (tester) async {
           final deactivatedUsers = [eg.user(isActive: false), eg.user(isActive: false)];
           await prepareComposeBox(tester, narrow: groupDmNarrowWith(deactivatedUsers),
-            users: deactivatedUsers);
+            otherUsers: deactivatedUsers);
           checkComposeBox(isShown: false);
 
           await changeUserStatus(tester, user: deactivatedUsers[0], isActive: true);
@@ -708,7 +880,7 @@ void main() {
 
       final narrowTestCases = [
         ('channel', const ChannelNarrow(1)),
-        ('topic',   const TopicNarrow(1, 'topic')),
+        ('topic',   eg.topicNarrow(1, 'topic')),
       ];
 
       for (final (String narrowType, Narrow narrow) in narrowTestCases) {
@@ -802,7 +974,7 @@ void main() {
   group('ComposeBox content input scaling', () {
     const verticalPadding = 8;
     final stream = eg.stream();
-    final narrow = TopicNarrow(stream.streamId, 'foo');
+    final narrow = eg.topicNarrow(stream.streamId, 'foo');
 
     Future<void> checkContentInputMaxHeight(WidgetTester tester, {
       required double maxHeight,
@@ -816,7 +988,7 @@ void main() {
       double? height;
       for (numLines = 2; numLines <= 1000; numLines++) {
         final content = List.generate(numLines, (_) => 'foo').join('\n');
-        await tester.enterText(contentInputFinder, content);
+        await enterContent(tester, content);
         await tester.pump();
         final newHeight = tester.getRect(contentInputFinder).height;
         if (newHeight == height) {
diff --git a/test/widgets/dialog_checks.dart b/test/widgets/dialog_checks.dart
index 504042d07e..af0c6e2963 100644
--- a/test/widgets/dialog_checks.dart
+++ b/test/widgets/dialog_checks.dart
@@ -1,4 +1,6 @@
+import 'package:checks/checks.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter_checks/flutter_checks.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:zulip/widgets/dialog.dart';
 
@@ -26,6 +28,11 @@ Widget checkErrorDialog(WidgetTester tester, {
       matching: find.widgetWithText(TextButton, 'OK')));
 }
 
+// TODO(#996) update this to check for per-platform flavors of alert dialog
+void checkNoErrorDialog(WidgetTester tester) {
+  check(find.byType(AlertDialog)).findsNothing();
+}
+
 /// In a widget test, check that [showSuggestedActionDialog] was called
 /// with the right text.
 ///
diff --git a/test/widgets/emoji_reaction_test.dart b/test/widgets/emoji_reaction_test.dart
index 58b4f64a77..89333ee1af 100644
--- a/test/widgets/emoji_reaction_test.dart
+++ b/test/widgets/emoji_reaction_test.dart
@@ -251,15 +251,15 @@ void main() {
     }
 
     check(backgroundColor('smile')).isNotNull()
-      .isSameColorAs(EmojiReactionTheme.light().bgSelected);
+      .isSameColorAs(EmojiReactionTheme.light.bgSelected);
     check(backgroundColor('tada')).isNotNull()
-      .isSameColorAs(EmojiReactionTheme.light().bgUnselected);
+      .isSameColorAs(EmojiReactionTheme.light.bgUnselected);
 
     tester.platformDispatcher.platformBrightnessTestValue = Brightness.dark;
     await tester.pump();
 
     await tester.pump(kThemeAnimationDuration * 0.4);
-    final expectedLerped = EmojiReactionTheme.light().lerp(EmojiReactionTheme.dark(), 0.4);
+    final expectedLerped = EmojiReactionTheme.light.lerp(EmojiReactionTheme.dark, 0.4);
     check(backgroundColor('smile')).isNotNull()
       .isSameColorAs(expectedLerped.bgSelected);
     check(backgroundColor('tada')).isNotNull()
@@ -267,9 +267,9 @@ void main() {
 
     await tester.pump(kThemeAnimationDuration * 0.6);
     check(backgroundColor('smile')).isNotNull()
-      .isSameColorAs(EmojiReactionTheme.dark().bgSelected);
+      .isSameColorAs(EmojiReactionTheme.dark.bgSelected);
     check(backgroundColor('tada')).isNotNull()
-      .isSameColorAs(EmojiReactionTheme.dark().bgUnselected);
+      .isSameColorAs(EmojiReactionTheme.dark.bgUnselected);
   });
 
   testWidgets('use emoji font', (tester) async {
diff --git a/test/widgets/home_test.dart b/test/widgets/home_test.dart
index 2939358bb8..5bb789727f 100644
--- a/test/widgets/home_test.dart
+++ b/test/widgets/home_test.dart
@@ -6,6 +6,7 @@ import 'package:zulip/api/model/events.dart';
 import 'package:zulip/model/narrow.dart';
 import 'package:zulip/model/store.dart';
 import 'package:zulip/widgets/about_zulip.dart';
+import 'package:zulip/widgets/actions.dart';
 import 'package:zulip/widgets/app.dart';
 import 'package:zulip/widgets/app_bar.dart';
 import 'package:zulip/widgets/home.dart';
@@ -21,6 +22,7 @@ import '../api/fake_api.dart';
 import '../example_data.dart' as eg;
 import '../flutter_checks.dart';
 import '../model/binding.dart';
+import '../model/store_checks.dart';
 import '../model/test_store.dart';
 import '../test_navigation.dart';
 import 'message_list_checks.dart';
@@ -49,6 +51,23 @@ void main () {
     await tester.pump();
   }
 
+  void checkOnLoadingPage() {
+    check(find.byType(CircularProgressIndicator).hitTestable()).findsOne();
+    check(find.byType(ChooseAccountPage)).findsNothing();
+    check(find.byType(HomePage)).findsNothing();
+  }
+
+  ModalRoute<void>? getRouteOf(WidgetTester tester, Finder finder) =>
+    ModalRoute.of(tester.element(finder));
+
+  void checkOnHomePage(WidgetTester tester, {required Account expectedAccount}) {
+    check(find.byType(CircularProgressIndicator)).findsNothing();
+    check(find.byType(ChooseAccountPage)).findsNothing();
+    check(find.byType(HomePage).hitTestable()).findsOne();
+    check(getRouteOf(tester, find.byType(HomePage)))
+      .isA<MaterialAccountWidgetRoute>().accountId.equals(expectedAccount.id);
+  }
+
   group('bottom nav navigation', () {
     testWidgets('preserve states when switching between views', (tester) async {
       await prepare(tester);
@@ -255,12 +274,6 @@ void main () {
     const loadPerAccountDuration = Duration(seconds: 30);
     assert(loadPerAccountDuration > kTryAnotherAccountWaitPeriod);
 
-    void checkOnLoadingPage() {
-      check(find.byType(CircularProgressIndicator).hitTestable()).findsOne();
-      check(find.byType(ChooseAccountPage)).findsNothing();
-      check(find.byType(HomePage)).findsNothing();
-    }
-
     void checkOnChooseAccountPage() {
       // Ignore the possible loading page in the background.
       check(find.byType(CircularProgressIndicator).hitTestable()).findsNothing();
@@ -268,17 +281,6 @@ void main () {
       check(find.byType(HomePage)).findsNothing();
     }
 
-    ModalRoute<void>? getRouteOf(WidgetTester tester, Finder finder) =>
-      ModalRoute.of(tester.element(finder));
-
-    void checkOnHomePage(WidgetTester tester, {required Account expectedAccount}) {
-      check(find.byType(CircularProgressIndicator)).findsNothing();
-      check(find.byType(ChooseAccountPage)).findsNothing();
-      check(find.byType(HomePage).hitTestable()).findsOne();
-      check(getRouteOf(tester, find.byType(HomePage)))
-        .isA<MaterialAccountWidgetRoute>().accountId.equals(expectedAccount.id);
-    }
-
     Future<void> prepare(WidgetTester tester) async {
       addTearDown(testBinding.reset);
       await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot());
@@ -442,4 +444,39 @@ void main () {
       checkOnHomePage(tester, expectedAccount: eg.selfAccount);
     });
   });
+
+  testWidgets('logging out while still loading', (tester) async {
+    // Regression test for: https://github.com/zulip/zulip-flutter/issues/1219
+    addTearDown(testBinding.reset);
+    await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot());
+    await tester.pumpWidget(const ZulipApp());
+    await tester.pump(); // wait for the loading page
+    checkOnLoadingPage();
+
+    final element = tester.element(find.byType(MaterialApp));
+    final future = logOutAccount(element, eg.selfAccount.id);
+    await tester.pump(TestGlobalStore.removeAccountDuration);
+    await future;
+    // No error expected from briefly not having
+    // access to the account being logged out.
+    check(testBinding.globalStore).accountIds.isEmpty();
+  });
+
+  testWidgets('logging out after fully loaded', (tester) async {
+    // Regression test for: https://github.com/zulip/zulip-flutter/issues/1219
+    addTearDown(testBinding.reset);
+    await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot());
+    await tester.pumpWidget(const ZulipApp());
+    await tester.pump(); // wait for the loading page
+    await tester.pump(); // wait for store
+    checkOnHomePage(tester, expectedAccount: eg.selfAccount);
+
+    final element = tester.element(find.byType(HomePage));
+    final future = logOutAccount(element, eg.selfAccount.id);
+    await tester.pump(TestGlobalStore.removeAccountDuration);
+    await future;
+    // No error expected from briefly not having
+    // access to the account being logged out.
+    check(testBinding.globalStore).accountIds.isEmpty();
+  });
 }
diff --git a/test/widgets/inbox_test.dart b/test/widgets/inbox_test.dart
index b7af250d03..3fa3713d5d 100644
--- a/test/widgets/inbox_test.dart
+++ b/test/widgets/inbox_test.dart
@@ -206,6 +206,8 @@ void main() {
     // TODO test that tapping a conversation row opens the message list
     //   for the conversation
 
+    // Tests for the topic action sheet are in test/widgets/action_sheet_test.dart.
+
     group('muting', () { // aka topic visibility
       testWidgets('baseline', (tester) async {
         final stream = eg.stream();
diff --git a/test/widgets/message_list_test.dart b/test/widgets/message_list_test.dart
index b1f443c8b5..b3cc208463 100644
--- a/test/widgets/message_list_test.dart
+++ b/test/widgets/message_list_test.dart
@@ -133,12 +133,14 @@ void main() {
   });
 
   group('app bar', () {
+    // Tests for the topic action sheet are in test/widgets/action_sheet_test.dart.
+
     testWidgets('has channel-feed action for topic narrows', (tester) async {
       final pushedRoutes = <Route<void>>[];
       final navObserver = TestNavigatorObserver()
         ..onPushed = (route, prevRoute) => pushedRoutes.add(route);
       final channel = eg.stream();
-      await setupMessageListPage(tester, narrow: TopicNarrow(channel.streamId, 'hi'),
+      await setupMessageListPage(tester, narrow: eg.topicNarrow(channel.streamId, 'hi'),
         navObservers: [navObserver],
         streams: [channel], messageCount: 1);
 
@@ -157,7 +159,7 @@ void main() {
       final channel = eg.stream();
       const topic = 'topic';
       await setupMessageListPage(tester,
-        narrow: TopicNarrow(channel.streamId, topic),
+        narrow: eg.topicNarrow(channel.streamId, topic),
         streams: [channel], subscriptions: [eg.subscription(channel)],
         messageCount: 1);
       await store.handleEvent(eg.userTopicEvent(
@@ -207,17 +209,17 @@ void main() {
       return widget.color;
     }
 
-    check(backgroundColor()).isSameColorAs(MessageListTheme.light().streamMessageBgDefault);
+    check(backgroundColor()).isSameColorAs(MessageListTheme.light.streamMessageBgDefault);
 
     tester.platformDispatcher.platformBrightnessTestValue = Brightness.dark;
     await tester.pump();
 
     await tester.pump(kThemeAnimationDuration * 0.4);
-    final expectedLerped = MessageListTheme.light().lerp(MessageListTheme.dark(), 0.4);
+    final expectedLerped = MessageListTheme.light.lerp(MessageListTheme.dark, 0.4);
     check(backgroundColor()).isSameColorAs(expectedLerped.streamMessageBgDefault);
 
     await tester.pump(kThemeAnimationDuration * 0.6);
-    check(backgroundColor()).isSameColorAs(MessageListTheme.dark().streamMessageBgDefault);
+    check(backgroundColor()).isSameColorAs(MessageListTheme.dark.streamMessageBgDefault);
   });
 
   group('fetch older messages on scroll', () {
@@ -661,7 +663,7 @@ void main() {
     const topic = 'foo';
     final channel = eg.stream();
     final otherChannel = eg.stream();
-    final narrow = TopicNarrow(channel.streamId, topic);
+    final narrow = eg.topicNarrow(channel.streamId, topic);
 
     void prepareGetMessageResponse(List<Message> messages) {
       connection.prepare(json: eg.newestGetMessagesResult(
@@ -671,7 +673,7 @@ void main() {
     void handleMessageMoveEvent(List<StreamMessage> messages, String newTopic, {int? newChannelId}) {
       store.handleEvent(eg.updateMessageEventMoveFrom(
         origMessages: messages,
-        newTopic: newTopic,
+        newTopicStr: newTopic,
         newStreamId: newChannelId,
         propagateMode: PropagateMode.changeAll));
     }
@@ -748,8 +750,11 @@ void main() {
 
   group('recipient headers', () {
     group('StreamMessageRecipientHeader', () {
+      // Tests for the topic action sheet are in test/widgets/action_sheet_test.dart.
+
       final stream = eg.stream(name: 'stream name');
-      final message = eg.streamMessage(stream: stream, topic: 'topic name');
+      const topic = 'topic name';
+      final message = eg.streamMessage(stream: stream, topic: topic);
 
       FinderResult<Element> findInMessageList(String text) {
         // Stream name shows up in [AppBar] so need to avoid matching that
@@ -808,7 +813,7 @@ void main() {
           narrow: const CombinedFeedNarrow(),
           messages: [message], subscriptions: [eg.subscription(stream)]);
         await store.handleEvent(eg.userTopicEvent(
-          stream.streamId, message.topic, UserTopicVisibilityPolicy.followed));
+          stream.streamId, topic, UserTopicVisibilityPolicy.followed));
         await tester.pump();
         check(find.descendant(
           of: find.byType(MessageList),
@@ -820,7 +825,7 @@ void main() {
           narrow: TopicNarrow.ofMessage(message),
           messages: [message], subscriptions: [eg.subscription(stream, isMuted: true)]);
         await store.handleEvent(eg.userTopicEvent(
-          stream.streamId, message.topic, UserTopicVisibilityPolicy.unmuted));
+          stream.streamId, topic, UserTopicVisibilityPolicy.unmuted));
         await tester.pump();
         check(find.descendant(
           of: find.byType(MessageList),
@@ -922,6 +927,54 @@ void main() {
         await tester.pump();
         tester.widget(find.text('new stream name'));
       });
+
+      testWidgets('navigates to TopicNarrow on tapping topic in ChannelNarrow', (tester) async {
+        final pushedRoutes = <Route<void>>[];
+        final navObserver = TestNavigatorObserver()
+          ..onPushed = (route, prevRoute) => pushedRoutes.add(route);
+        final channel = eg.stream();
+        final message = eg.streamMessage(stream: channel, topic: 'topic name');
+        await setupMessageListPage(tester,
+          narrow: ChannelNarrow(channel.streamId),
+          streams: [channel],
+          messages: [message],
+          navObservers: [navObserver]);
+
+        assert(pushedRoutes.length == 1);
+        pushedRoutes.clear();
+
+        connection.prepare(json: eg.newestGetMessagesResult(
+          foundOldest: true, messages: [message]).toJson());
+        await tester.tap(find.descendant(
+          of: find.byType(StreamMessageRecipientHeader),
+          matching: find.text('topic name')));
+        await tester.pump();
+        check(pushedRoutes).single.isA<WidgetRoute>().page.isA<MessageListPage>()
+          .initNarrow.equals(TopicNarrow.ofMessage(message));
+        await tester.pumpAndSettle();
+      });
+
+      testWidgets('does not navigate on tapping topic in TopicNarrow', (tester) async {
+        final pushedRoutes = <Route<void>>[];
+        final navObserver = TestNavigatorObserver()
+          ..onPushed = (route, prevRoute) => pushedRoutes.add(route);
+        final channel = eg.stream();
+        final message = eg.streamMessage(stream: channel, topic: 'topic name');
+        await setupMessageListPage(tester,
+          narrow: TopicNarrow.ofMessage(message),
+          streams: [channel],
+          messages: [message],
+          navObservers: [navObserver]);
+
+        assert(pushedRoutes.length == 1);
+        pushedRoutes.clear();
+
+        await tester.tap(find.descendant(
+          of: find.byType(StreamMessageRecipientHeader),
+          matching: find.text('topic name')));
+        await tester.pump();
+        check(pushedRoutes).isEmpty();
+      });
     });
 
     group('DmRecipientHeader', () {
@@ -987,6 +1040,46 @@ void main() {
       tester.widget(find.textContaining(RegExp("Dec 1[89], 2022")));
       tester.widget(find.textContaining(RegExp("Aug 2[23], 2022")));
     });
+
+    testWidgets('navigates to DmNarrow on tapping recipient header in CombinedFeedNarrow', (tester) async {
+      final pushedRoutes = <Route<void>>[];
+      final navObserver = TestNavigatorObserver()
+        ..onPushed = (route, prevRoute) => pushedRoutes.add(route);
+      final dmMessage = eg.dmMessage(from: eg.selfUser, to: [eg.otherUser]);
+      await setupMessageListPage(tester,
+        narrow: const CombinedFeedNarrow(),
+        messages: [dmMessage],
+        navObservers: [navObserver]);
+
+      assert(pushedRoutes.length == 1);
+      pushedRoutes.clear();
+
+      connection.prepare(json: eg.newestGetMessagesResult(
+        foundOldest: true, messages: [dmMessage]).toJson());
+      await tester.tap(find.byType(DmRecipientHeader));
+      await tester.pump();
+      check(pushedRoutes).single.isA<WidgetRoute>().page.isA<MessageListPage>()
+        .initNarrow.equals(DmNarrow.withUser(eg.otherUser.userId, selfUserId: eg.selfUser.userId));
+      await tester.pumpAndSettle();
+    });
+    
+    testWidgets('does not navigate on tapping recipient header in DmNarrow', (tester) async {
+      final pushedRoutes = <Route<void>>[];
+      final navObserver = TestNavigatorObserver()
+        ..onPushed = (route, prevRoute) => pushedRoutes.add(route);
+      final dmMessage = eg.dmMessage(from: eg.selfUser, to: [eg.otherUser]);
+      await setupMessageListPage(tester,
+        narrow: DmNarrow.withUser(eg.otherUser.userId, selfUserId: eg.selfUser.userId),
+        messages: [dmMessage],
+        navObservers: [navObserver]);
+
+      assert(pushedRoutes.length == 1);
+      pushedRoutes.clear();
+
+      await tester.tap(find.byType(DmRecipientHeader));
+      await tester.pump();
+      check(pushedRoutes).isEmpty();
+    });
   });
 
   group('formatHeaderDate', () {
@@ -1134,7 +1227,7 @@ void main() {
       checkMarkersCount(edited: 1, moved: 0);
 
       await store.handleEvent(eg.updateMessageEventMoveFrom(
-        origMessages: [message, message2], newTopic: 'new'));
+        origMessages: [message, message2], newTopicStr: 'new'));
       await tester.pump();
       checkMarkersCount(edited: 1, moved: 1);
 
diff --git a/test/widgets/page_checks.dart b/test/widgets/page_checks.dart
index 412a59fc49..a3692273bf 100644
--- a/test/widgets/page_checks.dart
+++ b/test/widgets/page_checks.dart
@@ -6,6 +6,6 @@ extension WidgetRouteChecks<T> on Subject<WidgetRoute<T>> {
   Subject<Widget> get page => has((x) => x.page, 'page');
 }
 
-extension AccountPageRouteMixinChecks<T> on Subject<AccountPageRouteMixin<T>> {
+extension AccountRouteChecks<T> on Subject<AccountRoute<T>> {
   Subject<int> get accountId => has((x) => x.accountId, 'accountId');
 }
diff --git a/test/widgets/sticky_header_test.dart b/test/widgets/sticky_header_test.dart
index fc363c71e8..c283652ae1 100644
--- a/test/widgets/sticky_header_test.dart
+++ b/test/widgets/sticky_header_test.dart
@@ -103,6 +103,116 @@ void main() {
       }
     }
   }
+
+  testWidgets('sticky headers: propagate scrollOffsetCorrection properly', (tester) async {
+    Widget page(Widget Function(BuildContext, int) itemBuilder) {
+      return Directionality(textDirection: TextDirection.ltr,
+        child: StickyHeaderListView.builder(
+          cacheExtent: 0,
+          itemCount: 10, itemBuilder: itemBuilder));
+    }
+
+    await tester.pumpWidget(page((context, i) =>
+      StickyHeaderItem(
+        allowOverflow: true,
+        header: _Header(i, height: 40),
+        child: _Item(i, height: 200))));
+    check(tester.getTopLeft(find.text("Item 2"))).equals(Offset(0, 400));
+
+    // Scroll down (dragging up) to get item 0 off screen.
+    await tester.drag(find.text("Item 2"), Offset(0, -300));
+    await tester.pump();
+    check(tester.getTopLeft(find.text("Item 2"))).equals(Offset(0, 100));
+
+    // Make the off-screen item 0 taller, so scrolling back up will underflow.
+    await tester.pumpWidget(page((context, i) =>
+      StickyHeaderItem(
+        allowOverflow: true,
+        header: _Header(i, height: 40),
+        child: _Item(i, height: i == 0 ? 400 : 200))));
+    // Confirm the change in item 0's height hasn't already been applied,
+    // as it would if the item were within the viewport or its cache area.
+    check(tester.getTopLeft(find.text("Item 2"))).equals(Offset(0, 100));
+
+    // Scroll back up (dragging down).  This will cause a correction as the list
+    // discovers that moving 300px up doesn't reach the start anymore.
+    await tester.drag(find.text("Item 2"), Offset(0, 300));
+
+    // As a bonus, mark one of the already-visible items as needing layout.
+    // (In a real app, this would typically happen because some state changed.)
+    tester.firstElement(find.widgetWithText(SizedBox, "Item 2"))
+      .renderObject!.markNeedsLayout();
+
+    // If scrollOffsetCorrection doesn't get propagated to the viewport, this
+    // pump will record an exception (causing the test to fail at the end)
+    // because the marked item won't get laid out.
+    await tester.pump();
+    check(tester.getTopLeft(find.text("Item 2"))).equals(Offset(0, 400));
+
+    // Moreover if scrollOffsetCorrection doesn't get propagated, this item
+    // will get placed at zero rather than properly extend up off screen.
+    check(tester.getTopLeft(find.text("Item 0"))).equals(Offset(0, -200));
+  });
+
+  testWidgets('sliver only part of viewport, header at end', (tester) async {
+    const centerKey = ValueKey('center');
+    final controller = ScrollController();
+    await tester.pumpWidget(Directionality(textDirection: TextDirection.ltr,
+      child: CustomScrollView(
+        controller: controller,
+        anchor: 0.5,
+        center: centerKey,
+        slivers: [
+          SliverStickyHeaderList(
+            headerPlacement: HeaderPlacement.scrollingStart,
+            delegate: SliverChildListDelegate(
+              List.generate(100, (i) => StickyHeaderItem(
+                header: _Header(99 - i, height: 20),
+                child: _Item(99 - i, height: 100))))),
+          SliverStickyHeaderList(
+            key: centerKey,
+            headerPlacement: HeaderPlacement.scrollingStart,
+            delegate: SliverChildListDelegate(
+              List.generate(100, (i) => StickyHeaderItem(
+                header: _Header(100 + i, height: 20),
+                child: _Item(100 + i, height: 100))))),
+        ])));
+
+    final overallSize = tester.getSize(find.byType(CustomScrollView));
+    final extent = overallSize.onAxis(Axis.vertical);
+    assert(extent == 600);
+
+    void checkState(int index, {required double item, required double header}) {
+      final itemElement = tester.firstElement(find.byElementPredicate((element) {
+        if (element.widget is! _Item) return false;
+        final renderObject = element.renderObject as RenderBox;
+        return (renderObject.size.contains(renderObject.globalToLocal(
+            Offset(overallSize.width / 2, 1)
+        )));
+      }));
+      final itemWidget = itemElement.widget as _Item;
+      check(itemWidget.index).equals(index);
+      check(_headerIndex(tester)).equals(index);
+      check((itemElement.renderObject as RenderBox).localToGlobal(Offset(0, 0)))
+        .equals(Offset(0, item));
+      check(tester.getTopLeft(find.byType(_Header))).equals(Offset(0, header));
+    }
+
+    check(controller.offset).equals(0);
+    checkState( 97, item:   0, header:   0);
+
+    controller.jumpTo(-5);
+    await tester.pump();
+    checkState( 96, item: -95, header: -15);
+
+    controller.jumpTo(-600);
+    await tester.pump();
+    checkState( 91, item:   0, header:   0);
+
+    controller.jumpTo(600);
+    await tester.pump();
+    checkState(103, item:   0, header:   0);
+  });
 }
 
 Future<void> _checkSequence(
@@ -174,7 +284,6 @@ Future<void> _checkSequence(
     final expectedHeaderIndex = first
       ? (scrollOffset / 100).floor()
       : (extent ~/ 100 - 1) + (scrollOffset / 100).ceil();
-    // print("$scrollOffset, $extent, $expectedHeaderIndex");
     check(tester.widget<_Item>(itemFinder).index).equals(expectedHeaderIndex);
     check(_headerIndex(tester)).equals(expectedHeaderIndex);
 
diff --git a/test/widgets/subscription_list_test.dart b/test/widgets/subscription_list_test.dart
index 9439bac865..a3fc13dac9 100644
--- a/test/widgets/subscription_list_test.dart
+++ b/test/widgets/subscription_list_test.dart
@@ -150,12 +150,35 @@ void main() {
       ]);
       check(listedStreamIds(tester)).deepEquals([2, 1, 3, 4, 6, 5]);
     });
+
+    testWidgets('channels with names starting with an emoji are above channel names that do not start with an emoji', (tester) async {
+      await setupStreamListPage(tester, subscriptions: [
+        eg.subscription(eg.stream(streamId: 1, name: 'Happy 😊 Stream')),
+        eg.subscription(eg.stream(streamId: 2, name: 'Alpha Stream')),
+        eg.subscription(eg.stream(streamId: 3, name: '🚀 Rocket Stream')),
+      ]);
+      check(listedStreamIds(tester)).deepEquals([3, 2, 1]);
+    });
+
+    testWidgets('channels with names starting with an emoji, pinned, unpinned, muted, and unmuted are sorted correctly', (tester) async {
+      await setupStreamListPage(tester, subscriptions: [
+        eg.subscription(eg.stream(streamId: 1, name: '😊 Happy Stream'), pinToTop: true, isMuted: false),
+        eg.subscription(eg.stream(streamId: 2, name: '🚀 Rocket Stream'), pinToTop: true, isMuted: true),
+        eg.subscription(eg.stream(streamId: 3, name: 'Alpha Stream'), pinToTop: true, isMuted: false),
+        eg.subscription(eg.stream(streamId: 4, name: 'Beta Stream'), pinToTop: true, isMuted: true),
+        eg.subscription(eg.stream(streamId: 5, name: '🌟 Star Stream'), pinToTop: false, isMuted: false),
+        eg.subscription(eg.stream(streamId: 6, name: '🔥 Fire Stream'), pinToTop: false, isMuted: true),
+        eg.subscription(eg.stream(streamId: 7, name: 'Gamma Stream'), pinToTop: false, isMuted: false),
+        eg.subscription(eg.stream(streamId: 8, name: 'Delta Stream'), pinToTop: false, isMuted: true),
+      ]);
+      check(listedStreamIds(tester)).deepEquals([1, 3, 2, 4, 5, 7, 6, 8]);
+    });
   });
 
   testWidgets('unread badge shows with unreads', (tester) async {
     final stream = eg.stream();
     final unreadMsgs = eg.unreadMsgs(channels: [
-      UnreadChannelSnapshot(streamId: stream.streamId, topic: 'a', unreadMessageIds: [1, 2]),
+      eg.unreadChannelMsgs(streamId: stream.streamId, topic: 'a', unreadMessageIds: [1, 2]),
     ]);
     await setupStreamListPage(tester, subscriptions: [
       eg.subscription(stream),
@@ -167,14 +190,14 @@ void main() {
   testWidgets('unread badge counts unmuted only', (tester) async {
     final stream = eg.stream();
     final unreadMsgs = eg.unreadMsgs(channels: [
-      UnreadChannelSnapshot(streamId: stream.streamId, topic: 'a', unreadMessageIds: [1, 2]),
-      UnreadChannelSnapshot(streamId: stream.streamId, topic: 'b', unreadMessageIds: [3]),
+      eg.unreadChannelMsgs(streamId: stream.streamId, topic: 'a', unreadMessageIds: [1, 2]),
+      eg.unreadChannelMsgs(streamId: stream.streamId, topic: 'b', unreadMessageIds: [3]),
     ]);
     await setupStreamListPage(tester,
       subscriptions: [eg.subscription(stream, isMuted: true)],
         userTopics: [UserTopicItem(
           streamId: stream.streamId,
-          topicName: 'b',
+          topicName: eg.t('b'),
           lastUpdated: 1234567890,
           visibilityPolicy: UserTopicVisibilityPolicy.unmuted,
         )],
@@ -198,7 +221,7 @@ void main() {
   testWidgets('muted unread badge shows when unreads are visible in channel but not inbox', (tester) async {
     final stream = eg.stream();
     final unreadMsgs = eg.unreadMsgs(channels: [
-      UnreadChannelSnapshot(streamId: stream.streamId, topic: 'b', unreadMessageIds: [3]),
+      eg.unreadChannelMsgs(streamId: stream.streamId, topic: 'b', unreadMessageIds: [3]),
     ]);
     await setupStreamListPage(tester,
       subscriptions: [eg.subscription(stream, isMuted: true)],
@@ -211,7 +234,7 @@ void main() {
   testWidgets('muted unread badge does not show when unreads are visible in both channel & inbox', (tester) async {
     final stream = eg.stream();
     final unreadMsgs = eg.unreadMsgs(channels: [
-      UnreadChannelSnapshot(streamId: stream.streamId, topic: 'b', unreadMessageIds: [3]),
+      eg.unreadChannelMsgs(streamId: stream.streamId, topic: 'b', unreadMessageIds: [3]),
     ]);
     await setupStreamListPage(tester,
       subscriptions: [eg.subscription(stream, isMuted: false)],
@@ -224,7 +247,7 @@ void main() {
   testWidgets('muted unread badge does not show when unreads are not visible in channel nor inbox', (tester) async {
     final stream = eg.stream();
     final unreadMsgs = eg.unreadMsgs(channels: [
-      UnreadChannelSnapshot(streamId: stream.streamId, topic: 'b', unreadMessageIds: [3]),
+      eg.unreadChannelMsgs(streamId: stream.streamId, topic: 'b', unreadMessageIds: [3]),
     ]);
     await setupStreamListPage(tester,
       subscriptions: [eg.subscription(stream, isMuted: true)],
@@ -237,7 +260,7 @@ void main() {
   testWidgets('color propagates to icon and badge', (tester) async {
     final stream = eg.stream();
     final unreadMsgs = eg.unreadMsgs(channels: [
-      UnreadChannelSnapshot(streamId: stream.streamId, topic: 'a', unreadMessageIds: [1, 2]),
+      eg.unreadChannelMsgs(streamId: stream.streamId, topic: 'a', unreadMessageIds: [1, 2]),
     ]);
     final subscription = eg.subscription(stream, color: Colors.red.argbInt);
     final swatch = ChannelColorSwatch.light(subscription.color);
@@ -275,8 +298,8 @@ void main() {
         eg.userTopicItem(stream2, 'b', UserTopicVisibilityPolicy.unmuted),
       ],
       unreadMsgs: eg.unreadMsgs(channels: [
-        UnreadChannelSnapshot(streamId: stream1.streamId, topic: 'a', unreadMessageIds: [1, 2]),
-        UnreadChannelSnapshot(streamId: stream2.streamId, topic: 'b', unreadMessageIds: [3]),
+        eg.unreadChannelMsgs(streamId: stream1.streamId, topic: 'a', unreadMessageIds: [1, 2]),
+        eg.unreadChannelMsgs(streamId: stream2.streamId, topic: 'b', unreadMessageIds: [3]),
       ]),
     );
 
@@ -310,10 +333,10 @@ void main() {
         eg.userTopicItem(mutedStreamWithNoUnmutedUnreads,   'd', UserTopicVisibilityPolicy.muted),
       ],
       unreadMsgs: eg.unreadMsgs(channels: [
-        UnreadChannelSnapshot(streamId: unmutedStreamWithUnmutedUnreads.streamId,   topic: 'a', unreadMessageIds: [1]),
-        UnreadChannelSnapshot(streamId: unmutedStreamWithNoUnmutedUnreads.streamId, topic: 'b', unreadMessageIds: [2]),
-        UnreadChannelSnapshot(streamId: mutedStreamWithUnmutedUnreads.streamId,     topic: 'c', unreadMessageIds: [3]),
-        UnreadChannelSnapshot(streamId: mutedStreamWithNoUnmutedUnreads.streamId,   topic: 'd', unreadMessageIds: [4]),
+        eg.unreadChannelMsgs(streamId: unmutedStreamWithUnmutedUnreads.streamId,   topic: 'a', unreadMessageIds: [1]),
+        eg.unreadChannelMsgs(streamId: unmutedStreamWithNoUnmutedUnreads.streamId, topic: 'b', unreadMessageIds: [2]),
+        eg.unreadChannelMsgs(streamId: mutedStreamWithUnmutedUnreads.streamId,     topic: 'c', unreadMessageIds: [3]),
+        eg.unreadChannelMsgs(streamId: mutedStreamWithNoUnmutedUnreads.streamId,   topic: 'd', unreadMessageIds: [4]),
       ]),
     );
 
diff --git a/test/widgets/test_app.dart b/test/widgets/test_app.dart
index 0a358484c4..e431aeaf23 100644
--- a/test/widgets/test_app.dart
+++ b/test/widgets/test_app.dart
@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 
 import 'package:zulip/generated/l10n/zulip_localizations.dart';
+import 'package:zulip/widgets/page.dart';
 import 'package:zulip/widgets/store.dart';
 import 'package:zulip/widgets/theme.dart';
 
@@ -9,12 +10,29 @@ class TestZulipApp extends StatelessWidget {
   const TestZulipApp({
     super.key,
     this.accountId,
+    this.skipAssertAccountExists = false,
     this.navigatorObservers,
     this.child = const Placeholder(),
-  });
+  }) : assert(!skipAssertAccountExists || accountId != null);
 
   final int? accountId;
 
+  /// Whether to proceed if [accountId] doesn't have an [Account] in the store.
+  ///
+  /// If this widget's [GlobalStoreWidget] loads
+  /// with no [Account] for [accountId],
+  /// [build] will error unless this param is true.
+  ///
+  /// Usually, this case is just a mistake;
+  /// the caller either forgot to add the account to the store
+  /// or they didn't want to simulate a per-account context in the first place.
+  ///
+  /// Sometimes we want to simulate an account's UI
+  /// just after the account is logged out (so is absent in the store)
+  /// but before we tear down that UI.
+  /// Pass true to silence the assertion in that case.
+  final bool skipAssertAccountExists;
+
   /// A list to pass through to [MaterialApp.navigatorObservers].
   final List<NavigatorObserver>? navigatorObservers;
 
@@ -27,8 +45,31 @@ class TestZulipApp extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return GlobalStoreWidget(
-      child: MaterialApp(
+    return GlobalStoreWidget(child: Builder(builder: (context) {
+      assert(() {
+        if (accountId != null && !skipAssertAccountExists) {
+          final account = GlobalStoreWidget.of(context).getAccount(accountId!);
+          if (account == null) {
+            throw FlutterError.fromParts([
+              ErrorSummary(
+                'TestZulipApp() was called with [accountId] but a corresponding '
+                'Account was not found in the GlobalStore.'),
+              ErrorHint(
+                'If [child] needs per-account data, consider calling '
+                '`testBinding.globalStore.add` before pumping `TestZulipApp`.'),
+              ErrorHint(
+                'If [child] is not specific to an account, omit [accountId].'),
+              ErrorHint(
+                'If you are testing behavior when an account is logged out, '
+                'consider building ZulipApp instead of TestZulipApp, '
+                'or pass `skipAssertAccountExists: true`.'),
+            ]);
+          }
+        }
+        return true;
+      }());
+
+      return MaterialApp(
         title: 'Zulip',
         localizationsDelegates: ZulipLocalizations.localizationsDelegates,
         supportedLocales: ZulipLocalizations.supportedLocales,
@@ -37,8 +78,9 @@ class TestZulipApp extends StatelessWidget {
         navigatorObservers: navigatorObservers ?? const [],
 
         home: accountId != null
-          ? PerAccountStoreWidget(accountId: accountId!, child: child)
-          : child,
-      ));
+          ? PerAccountStoreWidget(accountId: accountId!,
+              child: PageRoot(child: child))
+          : PageRoot(child: child));
+    }));
   }
 }
diff --git a/tools/customer-testing/setup.sh b/tools/customer-testing/setup.sh
new file mode 100755
index 0000000000..4e7659c7c2
--- /dev/null
+++ b/tools/customer-testing/setup.sh
@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+# Setup script for running Zulip's tests as part of the Flutter
+# "customer testing" suite:
+#   https://github.com/flutter/tests
+
+set -euo pipefail
+
+# Flutter's "customer testing" suite runs in two environments:
+#  * GitHub Actions for changes to the flutter/tests tree itself
+#    (which is just a registry of downstream test suites to run);
+#  * LUCI, at ci.chromium.org, for changes in Flutter.
+#
+# For background, see:
+#   https://github.com/flutter/flutter/issues/162041#issuecomment-2611129958
+
+if ! sudo -v; then
+    # In the LUCI environment sudo isn't available,
+    # but also the setup below isn't needed.  Skip it.
+    exit 0
+fi
+
+# Otherwise, assume we're in the GitHub Actions environment.
+
+
+# Install libsqlite3-dev.
+#
+# A few Zulip tests use SQLite, and so need libsqlite3.so.
+# (The actual databases involved are tiny and in-memory.)
+#
+# Both older and newer GitHub Actions images have the SQLite shared
+# library, from the libsqlite3-0 package.  But newer images
+# (ubuntu-24.04, which the ubuntu-latest alias switched to around
+# 2025-01) no longer have a symlink "libsqlite3.so" pointing to it,
+# which is part of the libsqlite3-dev package.  Install that.
+sudo apt install -y libsqlite3-dev