diff --git a/apps/agent/entrypoints/background/index.ts b/apps/agent/entrypoints/background/index.ts
index 3cdfb825..1ca4d940 100644
--- a/apps/agent/entrypoints/background/index.ts
+++ b/apps/agent/entrypoints/background/index.ts
@@ -31,6 +31,17 @@ export default defineBackground(() => {
 
   scheduledJobRuns()
 
+  // Track which tabs belong to each agent conversation for side panel management
+  const agentTabSets = new Map<string, Set<number>>()
+
+  chrome.tabs.onRemoved.addListener((tabId) => {
+    for (const [conversationId, tabSet] of agentTabSets) {
+      tabSet.delete(tabId)
+      // Prune empty entries to prevent unbounded growth
+      if (tabSet.size === 0) agentTabSets.delete(conversationId)
+    }
+  })
+
   chrome.action.onClicked.addListener(async (tab) => {
     if (tab.id) {
       await toggleSidePanel(tab.id)
@@ -91,6 +102,29 @@ export default defineBackground(() => {
         timestamp: Date.now(),
       })
     }
+
+    // Open side panel on tabs the agent interacts with
+    if (
+      message?.type === 'open-sidepanel-on-tab' &&
+      message?.tabId &&
+      message?.conversationId
+    ) {
+      const { tabId, conversationId } = message
+      let tabSet = agentTabSets.get(conversationId)
+      if (!tabSet) {
+        tabSet = new Set()
+        agentTabSets.set(conversationId, tabSet)
+      }
+      if (!tabSet.has(tabId)) {
+        tabSet.add(tabId)
+        openSidePanel(tabId).catch(() => {})
+      }
+    }
+
+    // Clean up tab tracking when conversation resets
+    if (message?.type === 'clear-agent-tabs' && message?.conversationId) {
+      agentTabSets.delete(message.conversationId)
+    }
   })
 
   sessionStorage.watch(async (newSession) => {
diff --git a/apps/agent/entrypoints/sidepanel/index/useChatSession.ts b/apps/agent/entrypoints/sidepanel/index/useChatSession.ts
index c9d13e7a..b5a21529 100644
--- a/apps/agent/entrypoints/sidepanel/index/useChatSession.ts
+++ b/apps/agent/entrypoints/sidepanel/index/useChatSession.ts
@@ -468,6 +468,13 @@ export const useChatSession = (options?: ChatSessionOptions) => {
   const resetConversation = () => {
     track(CONVERSATION_RESET_EVENT, { message_count: messages.length })
     stop()
+    // Clear agent tab tracking in background before generating new conversationId
+    chrome.runtime
+      .sendMessage({
+        type: 'clear-agent-tabs',
+        conversationId: conversationIdRef.current,
+      })
+      .catch(() => {})
     setConversationId(crypto.randomUUID())
     setMessages([])
     setTextToAction(new Map())
diff --git a/apps/agent/entrypoints/sidepanel/index/useNotifyActiveTab.tsx b/apps/agent/entrypoints/sidepanel/index/useNotifyActiveTab.tsx
index 14483e2a..3a4dc427 100644
--- a/apps/agent/entrypoints/sidepanel/index/useNotifyActiveTab.tsx
+++ b/apps/agent/entrypoints/sidepanel/index/useNotifyActiveTab.tsx
@@ -29,6 +29,7 @@ export const useNotifyActiveTab = ({
   conversationId: string
 }) => {
   const lastTabIdRef = useRef<number | null>(null)
+  const knownTabsRef = useRef<Set<number>>(new Set())
 
   const lastMessage = messages?.[messages.length - 1]
 
@@ -39,6 +40,11 @@ export const useNotifyActiveTab = ({
   const hasToolCalls = !!latestTool
   const toolTabId = extractTabId(latestTool as ToolUIPart | null)
 
+  // biome-ignore lint/correctness/useExhaustiveDependencies: intentionally reset when conversationId changes
+  useEffect(() => {
+    knownTabsRef.current = new Set()
+  }, [conversationId])
+
   useEffect(() => {
     const isStreaming = status === 'streaming'
     const previousTabId = lastTabIdRef.current
@@ -82,6 +88,18 @@ export const useNotifyActiveTab = ({
 
       if (cancelled || !targetTabId) return
 
+      // Open side panel on tabs the agent hasn't seen yet
+      if (!knownTabsRef.current.has(targetTabId)) {
+        knownTabsRef.current.add(targetTabId)
+        chrome.runtime
+          .sendMessage({
+            type: 'open-sidepanel-on-tab',
+            tabId: targetTabId,
+            conversationId,
+          })
+          .catch(() => {})
+      }
+
       if (previousTabId && previousTabId !== targetTabId) {
         const deactivateMessage: GlowMessage = {
           conversationId,