diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6e9cb34..8a33084 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,9 @@
 
 ## [Unreleased]
 
+- Added: explicit `app-it` dev-server recipes for Vite + React, SvelteKit, and Astro, including disk detection signals, port behavior, and loopback-only start commands.
+- Fixed: generated run scripts now preserve `$PORT`/`$API_PORT` inside configured start commands until the launcher has selected the runtime ports.
+- Changed: hardened the shared Swift `WKWebView` shell against unusable restored window frames by clamping saved frames to the visible display and enforcing a minimum first-launch size.
 - Added: `desktop:doctor` — a self-diagnosing command for generated `app-it` launchers (`scripts/desktop-doctor.sh`). Run `npm run desktop:doctor` long after the build session to get a short, issue-ready report on one launcher: config + placeholder leakage, installed/build `.app`, Info.plist identity, ad-hoc signature, quarantine / iCloud signature-breaking xattrs, preferred-vs-runtime port, stale PID, **whether the process on the runtime port is actually in the recorded supervisor's descendant tree** (reuses the launcher's reattach gate), start-command binary resolution on the launcher's PATH, log/state paths, and **template drift** (feature-probes the installed `wrapper`/`run` against the current templates — no version stamp needed). `--tail[=N]` appends the launcher log. It is a diagnostic, not a fixer: read-only, deterministic, local (no network, no new dependencies), and it says "probably" when a check can't be certain. The opt-in `--fix-safe` flag touches **only app-it's own generated state** — stale pid/port files, this bundle's stale LaunchServices registration, the rebuilt icon, and quarantine on the generated `.app` — never the user's product code, dependencies, config, or anything outside app-it's artifacts. macOS `app-it` plugin only (the `app-it-static` companion has a different runtime model). Embodies Core principle #8 (*runtime truth beats build-time guess*) for end users.
 - Added: `app-it-static` companion plugin (`plugins/app-it-static/`) — a macOS sibling of `app-it` for **finished or buildable** apps. Builds once, then serves the built output (`dist/`/`build/`/`out/`/…) from a tiny zero-dependency static server (~15 MB) or directly via `file://` (~0 MB) — **no dev server**, instead of the 300–700 MB a dev server holds. Reuses `app-it`'s native Swift WebKit window, icon pipeline, and one-folder Dock install (the five shared templates are byte-identical and CI guards them against drift). The served output is a snapshot; `desktop:rebuild` refreshes it. Inspired by r/ClaudeAI launch feedback (see README → Community nudge) and recorded in [ADR 0006](docs/decisions/0006-static-companion-snapshot-model.md).
 - Added: Windows beta scaffold (`plugins/app-it-windows/`) — a sibling plugin mirroring the macOS contract with Windows primitives (WPF + WebView2 host, PowerShell lifecycle scripts, multi-resolution `.ico`, Start Menu `.lnk`). Build + lint gated by a required `windows-latest` CI job; **untested on real hardware, looking for a maintainer.** See [docs/WINDOWS.md](docs/WINDOWS.md).
diff --git a/README.md b/README.md
index aa5ad00..f3c175e 100644
--- a/README.md
+++ b/README.md
@@ -27,9 +27,9 @@ Turn a local web project into a macOS Dock-launchable `.app` bundle — a native
   WHAT YOU HAVE               WHAT APP-IT DOES           WHAT YOU GET
   ───────────────────────     ──────────────────────     ───────────────────────────
   a local web project         inspects it from disk,     YourApp.app on your Dock
-  Vite, Next, or a static     picks a strategy, then     · its own icon
-  site, run with          ──▶ builds & signs a .app  ──▶ · native window, one click
-  `npm run dev` in a tab      around a WebKit shell      · ⌘Q quits & frees the port
+  Vite React, SvelteKit,      picks a strategy, then     · its own icon
+  Astro, Next, or static  ──▶ builds & signs a .app  ──▶ · native window, one click
+  sites (`npm run dev`)       around a WebKit shell      · ⌘Q quits & frees the port
 ```
 
 Under the hood, app-it:
diff --git a/docs/COMPATIBILITY.md b/docs/COMPATIBILITY.md
index 90cc8b7..bfec9bf 100644
--- a/docs/COMPATIBILITY.md
+++ b/docs/COMPATIBILITY.md
@@ -9,7 +9,7 @@
 | OS | macOS |
 | Primary shell | Swift `WKWebView` wrapper |
 | Fallback shell | Chrome `--app` mode |
-| Common targets | Vite, Next.js, static sites, local multi-server apps |
+| Common targets | Vite + React, SvelteKit, Astro, Next.js, static sites, local multi-server apps |
 | Install destination | `~/Applications/App It/` by default |
 | Signing | Ad-hoc local code signing only |
 
diff --git a/plugins/app-it-static/skills/app-it-static/templates/wrapper.swift b/plugins/app-it-static/skills/app-it-static/templates/wrapper.swift
index fd97d42..cde8a93 100644
--- a/plugins/app-it-static/skills/app-it-static/templates/wrapper.swift
+++ b/plugins/app-it-static/skills/app-it-static/templates/wrapper.swift
@@ -38,6 +38,8 @@ import WebKit
 
 private let DEFAULT_WIDTH: CGFloat = 1280
 private let DEFAULT_HEIGHT: CGFloat = 820
+private let MIN_WIDTH: CGFloat = 720
+private let MIN_HEIGHT: CGFloat = 480
 
 final class AppDelegate: NSObject,
     NSApplicationDelegate,
@@ -84,6 +86,7 @@ final class AppDelegate: NSObject,
         installKeyboardShortcutMonitor()
 
         let frame = NSRect(x: 0, y: 0, width: DEFAULT_WIDTH, height: DEFAULT_HEIGHT)
+        let autosaveName = "App-itWindow.\(appName)"
 
         window = NSWindow(
             contentRect: frame,
@@ -92,10 +95,11 @@ final class AppDelegate: NSObject,
             defer: false
         )
         window.title = appName
-        window.setFrameAutosaveName("App-itWindow.\(appName)")
+        window.setFrameAutosaveName(autosaveName)
+        window.minSize = NSSize(width: MIN_WIDTH, height: MIN_HEIGHT)
         window.tabbingMode = .disallowed
         window.delegate = self
-        window.center()
+        restoreUsableWindowFrame(named: autosaveName)
 
         let config = WKWebViewConfiguration()
         config.websiteDataStore = .default()
@@ -139,6 +143,56 @@ final class AppDelegate: NSObject,
         NSApp.activate(ignoringOtherApps: true)
     }
 
+    private func restoreUsableWindowFrame(named autosaveName: String) {
+        // AppKit can restore a frame saved on a now-disconnected display, or a
+        // tiny frame saved before the WebKit shell had a minimum size. Clamp
+        // the restored frame into a visible screen before the first paint so
+        // the WKWebView opens usable instead of off-screen or postage-stamp.
+        if !window.setFrameUsingName(autosaveName) {
+            window.center()
+        }
+
+        guard let screen = bestScreen(for: window.frame) else { return }
+        var frame = window.frame
+        let visible = screen.visibleFrame
+
+        frame.size.width = min(max(frame.size.width, MIN_WIDTH), visible.width)
+        frame.size.height = min(max(frame.size.height, MIN_HEIGHT), visible.height)
+
+        if frame.maxX > visible.maxX {
+            frame.origin.x = visible.maxX - frame.size.width
+        }
+        if frame.minX < visible.minX {
+            frame.origin.x = visible.minX
+        }
+        if frame.maxY > visible.maxY {
+            frame.origin.y = visible.maxY - frame.size.height
+        }
+        if frame.minY < visible.minY {
+            frame.origin.y = visible.minY
+        }
+
+        window.setFrame(frame, display: false)
+    }
+
+    private func bestScreen(for frame: NSRect) -> NSScreen? {
+        // When a frame straddles two displays, the first intersecting screen is
+        // arbitrary. Pick the screen holding the largest slice of the frame, and
+        // only fall back to main/first when nothing intersects at all.
+        var best: NSScreen?
+        var largestArea: CGFloat = 0
+        for screen in NSScreen.screens {
+            let overlap = screen.visibleFrame.intersection(frame)
+            guard !overlap.isNull else { continue }
+            let area = overlap.width * overlap.height
+            if area > largestArea {
+                largestArea = area
+                best = screen
+            }
+        }
+        return best ?? NSScreen.main ?? NSScreen.screens.first
+    }
+
     private var hasSynthesizedGesture = false
 
     func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
diff --git a/plugins/app-it/skills/app-it/SKILL.md b/plugins/app-it/skills/app-it/SKILL.md
index f74e4d8..2b8d6c4 100644
--- a/plugins/app-it/skills/app-it/SKILL.md
+++ b/plugins/app-it/skills/app-it/SKILL.md
@@ -190,6 +190,18 @@ For A3 multi-server, add `"backend_port"` and `"backend_start_command"`. The bui
 
 Edits should be minimal and additive (env-var reads with sensible defaults), so existing developer workflows (`npm run dev` from terminal without env vars set) keep working unchanged.
 
+### Framework dev recipes
+
+Use these when disk signals are unambiguous. Examples use `npm`; translate to
+the package manager actually present in the project while preserving the same
+script arguments.
+
+| Framework | Reliable detection signals | Preferred port | `START_COMMAND` | Notes |
+|---|---|---:|---|---|
+| Vite + React | `vite.config.*`; `package.json` has `vite`, `react`, `react-dom`, and `@vitejs/plugin-react` or `@vitejs/plugin-react-swc`; fresh apps usually have `src/main.jsx` or `src/main.tsx` | 5173 | `npm run dev -- --host 127.0.0.1 --port "$PORT" --strictPort` | Vanilla single-server path. The CLI flags beat `vite.config.*` port literals without source edits. If a proxy target or backend port is hardcoded, route to A3.2 and make the ports env-driven. |
+| SvelteKit | `svelte.config.*`; `package.json` has `@sveltejs/kit`, `@sveltejs/vite-plugin-svelte`, `svelte`, and `vite` | 5173 | `npm run dev -- --host 127.0.0.1 --port "$PORT" --strictPort` | SvelteKit runs through Vite, so use Vite CLI port flags instead of relying on `PORT` alone. First launch must happen after dependencies are installed. |
+| Astro | `astro.config.*`; `package.json` has `astro`; `scripts.dev` is usually `astro dev` | 4321 | `npm run dev -- --host 127.0.0.1 --port "$PORT"` | Astro's dev server accepts `--port`, and the explicit flag works across current Astro releases. Keep the host loopback-only; do not use `--host 0.0.0.0`. |
+
 Never:
 - Modify app business-logic source code.
 - Add runtime dependencies for Strategy A.
@@ -511,13 +523,13 @@ Hard-won from real-project iteration. Do not rediscover these:
 | Framework | Default behavior | What `START_COMMAND` should do |
 |---|---|---|
 | Next.js (`next dev`) | reads `PORT` env, exits if busy | nothing — works out of the box. **But** check `package.json` `"dev"` for hardcoded `-p N`; if present, replace with `pnpm exec next dev` (or add `dev:app-it`). |
-| Vite (vanilla, no proxy) | reads config's `server.port` literal; `strictPort: false` silently bumps | `npm run dev -- --port "$PORT"` — CLI flag wins over config literal. No source edits. |
+| Vite + React / vanilla Vite (no proxy) | reads config's `server.port` literal; `strictPort: false` silently bumps | `npm run dev -- --host 127.0.0.1 --port "$PORT" --strictPort` — CLI flags win over config literals. No source edits. |
 | Vite (cohabiting w/ proxy) | as above, plus proxy target hardcoded | edit `vite.config.ts`: `server.port` reads `process.env.PORT`; `strictPort: true`; `server.proxy.<route>.target` reads `process.env.API_PORT`. |
+| SvelteKit | Vite-backed; `PORT` alone is not the reliable contract | `npm run dev -- --host 127.0.0.1 --port "$PORT" --strictPort`. |
 | Express (typical) | `process.env.PORT \|\| 3001` | none — works. For cohabiting, rename to `API_PORT` in the entrypoint. |
 | Flask | reads `PORT`/`FLASK_RUN_PORT` env | none. |
 | CRA (`react-scripts start`) | reads `PORT` env | none. |
-| Astro 4+ | reads `PORT` env | none. |
-| Astro 3 | needs `--port` flag | embed `--port "$PORT"` in `START_COMMAND`. |
+| Astro | current releases accept `--port`; older Astro needed the flag | `npm run dev -- --host 127.0.0.1 --port "$PORT"`. |
 | Docusaurus | needs `--port` flag | embed `--port "$PORT"`. |
 
 **Recommended PORT-respecting invocations per package manager:**
@@ -693,9 +705,12 @@ Replace `assets/<slug>-icon.png`, then `pnpm desktop:icons:<app> && pnpm desktop
 | Signal | Strategy | Notes |
 |---|---|---|
 | `next.config.*`, dev on `:3000` | A1 native | Check `dev` script for `-p N` literal; bypass via `pnpm exec next dev` if found. |
+| `vite.config.*` + React deps (`react`, `react-dom`, `@vitejs/plugin-react*`) | A1 native | Vite + React recipe: `START_COMMAND="npm run dev -- --host 127.0.0.1 --port \"\$PORT\" --strictPort"`. |
 | `vite.config.*` + existing `dist/` | A2 | Static — `file://` URL, no server. |
-| `vite.config.*` no build (vanilla) | A1 native | `START_COMMAND="npm run dev -- --port \$PORT"` — CLI flag wins over config literal. |
+| `vite.config.*` no build (vanilla) | A1 native | `START_COMMAND="npm run dev -- --host 127.0.0.1 --port \"\$PORT\" --strictPort"` — CLI flags win over config literals. |
 | `vite.config.*` + proxy block | A3.2 | Make ports env-driven (3 vite-config edits + 1 server-entry edit). |
+| `svelte.config.*` + `@sveltejs/kit` | A1 native | SvelteKit recipe: Vite-backed dev server, use `--port "$PORT" --strictPort`; do not treat adapter choice as static unless using app-it-static. |
+| `astro.config.*` + `astro` dependency | A1 native | Astro recipe: default preferred port 4321, `START_COMMAND="npm run dev -- --host 127.0.0.1 --port \"\$PORT\""`. |
 | `concurrently` / `npm-run-all -p` / `turbo run dev` in `dev` | A3.1 | Reuse orchestrator as single START_COMMAND. |
 | `apps/web` + `apps/api` (cohabiting, no orchestrator) | A3.2 | Multi-server template. |
 | `apps/web` + `apps/studio` (separate) | A1 native × 2 | Two `.app`s. |
diff --git a/plugins/app-it/skills/app-it/templates/inspect.sh b/plugins/app-it/skills/app-it/templates/inspect.sh
index 6d515a7..2187d8b 100755
--- a/plugins/app-it/skills/app-it/templates/inspect.sh
+++ b/plugins/app-it/skills/app-it/templates/inspect.sh
@@ -40,7 +40,7 @@ if [ -d "$ROOT/.git" ] || [ -f "$ROOT/.git" ]; then
 fi
 
 print_section "Project type signals (verify from disk, ignore CLAUDE.md)"
-for f in package.json next.config.ts next.config.js next.config.mjs vite.config.ts vite.config.js vite.config.mjs tauri.conf.json electron.json electron-builder.yml electron-builder.json pyproject.toml requirements.txt Cargo.toml Gemfile manifest.json index.html; do
+for f in package.json next.config.ts next.config.js next.config.mjs vite.config.ts vite.config.js vite.config.mjs astro.config.ts astro.config.js astro.config.mjs svelte.config.ts svelte.config.js svelte.config.mjs tauri.conf.json electron.json electron-builder.yml electron-builder.json pyproject.toml requirements.txt Cargo.toml Gemfile manifest.json index.html; do
     [ -f "$ROOT/$f" ] && echo "  $f" || true
 done
 [ -d "$ROOT/src-tauri" ] && echo "  src-tauri/ (Tauri project)" || true
@@ -76,6 +76,35 @@ for k, v in matched:
 print()
 print(f"  package.json name:        {pkg.get('name', '(none)')}")
 print(f"  package.json displayName: {pkg.get('displayName', '(none)')}")
+
+deps = {}
+for section in ("dependencies", "devDependencies", "optionalDependencies"):
+    deps.update(pkg.get(section, {}))
+
+def has(name):
+    return name in deps
+
+recipes = []
+if has("vite") and has("react") and has("react-dom") and (
+    has("@vitejs/plugin-react") or has("@vitejs/plugin-react-swc")
+):
+    recipes.append(
+        "Vite + React — port 5173; start_command '<pm> run dev -- --host 127.0.0.1 --port $PORT --strictPort'"
+    )
+if has("@sveltejs/kit") and has("@sveltejs/vite-plugin-svelte") and has("svelte") and has("vite"):
+    recipes.append(
+        "SvelteKit — port 5173; start_command '<pm> run dev -- --host 127.0.0.1 --port $PORT --strictPort'"
+    )
+if has("astro"):
+    recipes.append(
+        "Astro — port 4321; start_command '<pm> run dev -- --host 127.0.0.1 --port $PORT'"
+    )
+
+if recipes:
+    print()
+    print("  framework recipe candidates:")
+    for recipe in recipes:
+        print(f"    - {recipe}")
 PY
 fi
 
@@ -85,7 +114,7 @@ if [ -f "$ROOT/vite.config.ts" ] || [ -f "$ROOT/vite.config.js" ] || [ -f "$ROOT
         [ -f "$cfg" ] || continue
         if grep -nE 'server:\s*\{[^}]*port:\s*[0-9]+' "$cfg" 2>/dev/null | head -3; then
             echo "  → vite.config.ts has hardcoded server.port literal."
-            echo "    Vanilla single-server: pass --port via START_COMMAND ('npm run dev -- --port \$PORT')."
+            echo "    Vanilla single-server: pass CLI flags via START_COMMAND ('npm run dev -- --host 127.0.0.1 --port \$PORT --strictPort')."
             echo "    Multi-server / proxy: edit vite.config.ts — see SKILL.md A3.2 carve-out."
         fi
         if grep -nE 'proxy:\s*\{[^}]*target:\s*["'"'"']http://localhost:[0-9]+' "$cfg" 2>/dev/null | head -3; then
diff --git a/plugins/app-it/skills/app-it/templates/run-template-chrome.sh b/plugins/app-it/skills/app-it/templates/run-template-chrome.sh
index 14ec299..6a50226 100755
--- a/plugins/app-it/skills/app-it/templates/run-template-chrome.sh
+++ b/plugins/app-it/skills/app-it/templates/run-template-chrome.sh
@@ -25,9 +25,16 @@ APP_NAME="__APP_NAME__"
 APP_SLUG="__APP_SLUG__"
 PROJECT_ROOT="__PROJECT_ROOT__"
 PREFERRED_PORT=__PORT__
-START_COMMAND="__START_COMMAND__"
 POLYFILL_PATH="__POLYFILL_PATH__"
 
+# Keep `$PORT` and other shell syntax literal until the daemon spawns below.
+# A plain double-quoted assignment here would expand `$PORT` before the
+# launcher has selected its runtime port, breaking Vite/SvelteKit recipes.
+START_COMMAND="$(cat <<'APP_IT_START_COMMAND'
+__START_COMMAND__
+APP_IT_START_COMMAND
+)"
+
 STATE_DIR="$HOME/Library/Application Support/app-it/$APP_SLUG"
 LOG_DIR="$HOME/Library/Logs/app-it/$APP_SLUG"
 mkdir -p "$STATE_DIR" "$LOG_DIR"
diff --git a/plugins/app-it/skills/app-it/templates/run-template-multiserver.sh b/plugins/app-it/skills/app-it/templates/run-template-multiserver.sh
index 91ebb0c..a8a2c95 100755
--- a/plugins/app-it/skills/app-it/templates/run-template-multiserver.sh
+++ b/plugins/app-it/skills/app-it/templates/run-template-multiserver.sh
@@ -34,11 +34,21 @@ APP_NAME="__APP_NAME__"
 APP_SLUG="__APP_SLUG__"
 PROJECT_ROOT="__PROJECT_ROOT__"
 PREFERRED_FE_PORT=__PORT__
-START_COMMAND="__START_COMMAND__"
 PREFERRED_BE_PORT=__BACKEND_PORT__
-BACKEND_START_COMMAND="__BACKEND_START_COMMAND__"
 POLYFILL_PATH="__POLYFILL_PATH__"
 
+# Keep `$PORT` / `$API_PORT` and other shell syntax literal until the daemon
+# spawns below. A plain double-quoted assignment here would expand those values
+# before the launcher has selected its runtime ports.
+START_COMMAND="$(cat <<'APP_IT_START_COMMAND'
+__START_COMMAND__
+APP_IT_START_COMMAND
+)"
+BACKEND_START_COMMAND="$(cat <<'APP_IT_BACKEND_START_COMMAND'
+__BACKEND_START_COMMAND__
+APP_IT_BACKEND_START_COMMAND
+)"
+
 STATE_DIR="$HOME/Library/Application Support/app-it/$APP_SLUG"
 LOG_DIR="$HOME/Library/Logs/app-it/$APP_SLUG"
 mkdir -p "$STATE_DIR" "$LOG_DIR"
diff --git a/plugins/app-it/skills/app-it/templates/run-template.sh b/plugins/app-it/skills/app-it/templates/run-template.sh
index 8d26584..2d2de8b 100755
--- a/plugins/app-it/skills/app-it/templates/run-template.sh
+++ b/plugins/app-it/skills/app-it/templates/run-template.sh
@@ -32,9 +32,16 @@ APP_NAME="__APP_NAME__"
 APP_SLUG="__APP_SLUG__"
 PROJECT_ROOT="__PROJECT_ROOT__"
 PREFERRED_PORT=__PORT__
-START_COMMAND="__START_COMMAND__"
 POLYFILL_PATH="__POLYFILL_PATH__"
 
+# Keep `$PORT` and other shell syntax literal until the daemon spawns below.
+# A plain double-quoted assignment here would expand `$PORT` before the
+# launcher has selected its runtime port, breaking Vite/SvelteKit recipes.
+START_COMMAND="$(cat <<'APP_IT_START_COMMAND'
+__START_COMMAND__
+APP_IT_START_COMMAND
+)"
+
 STATE_DIR="$HOME/Library/Application Support/app-it/$APP_SLUG"
 LOG_DIR="$HOME/Library/Logs/app-it/$APP_SLUG"
 mkdir -p "$STATE_DIR" "$LOG_DIR"
diff --git a/plugins/app-it/skills/app-it/templates/wrapper.swift b/plugins/app-it/skills/app-it/templates/wrapper.swift
index fd97d42..cde8a93 100644
--- a/plugins/app-it/skills/app-it/templates/wrapper.swift
+++ b/plugins/app-it/skills/app-it/templates/wrapper.swift
@@ -38,6 +38,8 @@ import WebKit
 
 private let DEFAULT_WIDTH: CGFloat = 1280
 private let DEFAULT_HEIGHT: CGFloat = 820
+private let MIN_WIDTH: CGFloat = 720
+private let MIN_HEIGHT: CGFloat = 480
 
 final class AppDelegate: NSObject,
     NSApplicationDelegate,
@@ -84,6 +86,7 @@ final class AppDelegate: NSObject,
         installKeyboardShortcutMonitor()
 
         let frame = NSRect(x: 0, y: 0, width: DEFAULT_WIDTH, height: DEFAULT_HEIGHT)
+        let autosaveName = "App-itWindow.\(appName)"
 
         window = NSWindow(
             contentRect: frame,
@@ -92,10 +95,11 @@ final class AppDelegate: NSObject,
             defer: false
         )
         window.title = appName
-        window.setFrameAutosaveName("App-itWindow.\(appName)")
+        window.setFrameAutosaveName(autosaveName)
+        window.minSize = NSSize(width: MIN_WIDTH, height: MIN_HEIGHT)
         window.tabbingMode = .disallowed
         window.delegate = self
-        window.center()
+        restoreUsableWindowFrame(named: autosaveName)
 
         let config = WKWebViewConfiguration()
         config.websiteDataStore = .default()
@@ -139,6 +143,56 @@ final class AppDelegate: NSObject,
         NSApp.activate(ignoringOtherApps: true)
     }
 
+    private func restoreUsableWindowFrame(named autosaveName: String) {
+        // AppKit can restore a frame saved on a now-disconnected display, or a
+        // tiny frame saved before the WebKit shell had a minimum size. Clamp
+        // the restored frame into a visible screen before the first paint so
+        // the WKWebView opens usable instead of off-screen or postage-stamp.
+        if !window.setFrameUsingName(autosaveName) {
+            window.center()
+        }
+
+        guard let screen = bestScreen(for: window.frame) else { return }
+        var frame = window.frame
+        let visible = screen.visibleFrame
+
+        frame.size.width = min(max(frame.size.width, MIN_WIDTH), visible.width)
+        frame.size.height = min(max(frame.size.height, MIN_HEIGHT), visible.height)
+
+        if frame.maxX > visible.maxX {
+            frame.origin.x = visible.maxX - frame.size.width
+        }
+        if frame.minX < visible.minX {
+            frame.origin.x = visible.minX
+        }
+        if frame.maxY > visible.maxY {
+            frame.origin.y = visible.maxY - frame.size.height
+        }
+        if frame.minY < visible.minY {
+            frame.origin.y = visible.minY
+        }
+
+        window.setFrame(frame, display: false)
+    }
+
+    private func bestScreen(for frame: NSRect) -> NSScreen? {
+        // When a frame straddles two displays, the first intersecting screen is
+        // arbitrary. Pick the screen holding the largest slice of the frame, and
+        // only fall back to main/first when nothing intersects at all.
+        var best: NSScreen?
+        var largestArea: CGFloat = 0
+        for screen in NSScreen.screens {
+            let overlap = screen.visibleFrame.intersection(frame)
+            guard !overlap.isNull else { continue }
+            let area = overlap.width * overlap.height
+            if area > largestArea {
+                largestArea = area
+                best = screen
+            }
+        }
+        return best ?? NSScreen.main ?? NSScreen.screens.first
+    }
+
     private var hasSynthesizedGesture = false
 
     func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {