[JustYannicc]

Problem

On mobile, opening Agent's browser (fork) or the browser preview (upstream) throws Render Error: undefined is not a function in createNativeStackNavigator.js. Closes #662 and #619: they're the same bug.

pnpm-workspace.yaml overrides @react-navigation/core to 7.21.13 (added upstream in pingdotgg/t3code#10663 for TypeScript 7). Upstream's Expo bump (#20067) then moved @react-navigation/native to 7.5.1, which requires core ^7.24.0, and native-stack to 7.21.0, which calls the render() that useNavigationBuilder only returns from newer core. The override silently forced the old core, so every plain createNativeStackNavigator throws on mount. The app's own stacks use createV5StackNavigator (which reads NavigationContent), so on iOS only the two nested-stack screens crash; on Android upstream reports it crashes at launch.

Fix

• Move the override to 7.24.0. This is byte-for-byte the workspace change in upstream's open fix(mobile): the app builds and launches again after the Expo update pingdotgg/t3code#20131, so the next upstream merge applies cleanly. 7.24.0 still returns the deprecated NavigationContent, so the custom navigators keep working, and the mobile typecheck passes, so the TypeScript 7 problem the override exists for doesn't come back.
• Lockfile trimmed to the navigation change only (core 7.24.0, routers 7.6.5, query-string and its deps dropped); pnpm install --frozen-lockfile passes.
• apps/mobile/src/navigation-dependencies.test.ts walks the installed @react-navigation/* graph from the app and fails when any package resolves outside another's declared range. It fails on main with @react-navigation/native@7.5.1 wants @react-navigation/core@^7.24.0, got 7.21.13 and passes here. That's the guard for the next time the override doesn't move with native.

Verification

• vp test run src/navigation-dependencies.test.ts: red on main, green here.
• tsc-rs --noEmit in apps/mobile: clean.
• iPhone 17 simulator (iOS 26.5, Xcode 27 runner per Mobile walks fail on this Mac: agent-device's XCUITest runner never starts (Xcode 26.5) #470) against the fix(mobile): Agent's browser and browser preview no longer crash on open #665 preview, signed in by email. With main's lockfile the core resolves to 7.21.13 and both screens throw the render error; with this branch (core 7.24.0) both open. Upstream's BrowserPreviewRouteScreen crashes the same way, so Upstream's mobile browser screen likely crashes on iOS (nested stack navigator) #619 is this bug.
• Opened Agent's browser from the thread header on a real test thread (Opus 5.5 opened a Wikipedia page): the screen opens, the status reads "The agent is driving" while the turn runs, and steps stream in live. The mirror pane itself was blank; that's a separate bug (the WebView refused Cloudflare's /agent-browser.html redirect), fixed in fix(mobile): Agent's browser shows the agent's page instead of a blank pane #706. With both applied, the mirror shows the agent's page and tapping a link in it opens my own copy in the thread's tabs.
• Android: no emulator installed on this machine, so not walked. The cause is shared JS, and upstream's fix(mobile): the app builds and launches again after the Expo update pingdotgg/t3code#20131 reports the same crash at Android launch.

	Agent's browser	Browser preview (upstream screen)
Before (main)
After

Upstream: pingdotgg/t3code#20131 (open, not ours) already makes this exact override change for the Android launch crash but couldn't check iOS. A comment with the iOS evidence is drafted in upstream-drafts/20131-ios-comment.md, not posted.

🤖 Generated with Claude Code

[JustYannicc]

From the #654 review: with this PR applied locally on an iOS 26.5 simulator against the #654 preview, Agent's browser opened without the crash, and the #579 banner, status and Done all worked. The mirror area itself stayed blank on mobile, though: both while resting and while someone drove the tab from web, where the page rendered fine. Please check that the WebView renders the mirror once the crash is fixed; it may be a separate issue.

[JustYannicc]

Merged by the coordinator. CI was green on the head, with no bot findings. The builder's live proof is in this PR. A scratch merge of current main with #665, #706, #688, #693 and #651 passed: contracts 676 tests, automations 24, the api parity check 21, cloud GitHub and automations 38, mobile 17, plus server layer, compiler and upstream-sync hook tests. Typecheck was clean for contracts, cloud, server, web and mobile.