[nwparker]

What

The mobile session screen (session/[worktreeId].tsx) runs a fallback poll that sends both session.tabs.list AND terminal.list every 2 seconds while the route is focused. useFocusEffect stops it when you navigate away, but not when the app goes to background — so a connected phone in your pocket kept firing ~60 RPC/min (plus host work + a radio wakeup) on this screen.

This applies the same fix as #9857 (host screen): gate the 2s poll on AppState.currentState === 'active' and immediately reconcile both lists on foreground return.

• The interval now calls a refreshOnForeground that returns early unless the app is active.
• An AppState 'change' listener (attached before the immediate focus refresh, to cover the attach race) refetches both lists on return to 'active'.
• Cleanup clears the interval and removes the listener.

The live session.tabs.subscribe subscription and the terminal streams are untouched — those carry live data with no polling replacement.

ELI5

When you had a terminal session open on your phone and put the phone away, it kept asking the computer "what tabs and terminals exist?" twice a second forever. Now it pauses that while the app is backgrounded and instantly catches up the moment you return. The live terminal output stream is never touched.

Proof of zero regression

• Live subscriptions (session.tabs.subscribe, terminal streams) and existing in-flight / modal / optimistic-reconciliation behavior are preserved; only the fallback list poll is background-gated.
• Foreground behavior is unchanged: on focus (which only happens while active) it still refreshes immediately, and the AppState listener guarantees an immediate refresh on any background→foreground transition, so the view is never stale on resume.
• Verified in a deps-installed mobile checkout: pnpm typecheck clean, full mobile suite 2228 pass / 2 skipped (306 files), oxlint clean (screen stays within its frozen max-lines budget), oxfmt --check clean. Added test covers: early background return, both fetches while active, listener-before-refresh ordering, resume refresh, the 2s interval, and both cleanup paths.

Proof of perf improvement

While backgrounded this stops ~60 RPC/min (session.tabs.list + terminal.list) and the associated host work + radio wakeups on the session screen; the added test asserts the poll body returns without issuing either RPC while AppState !== 'active', and refetches on resume. Foreground steady-state keeps the exact 2s fallback cadence. Companion to #9857 (host screen).

Made with Orca 🐋

[coderabbitai]

📝 Walkthrough

Walkthrough

Updated session polling to check for an active app state before fetching session tabs and terminals. The session screen now refreshes immediately when the app returns to the foreground, schedules guarded polling every two seconds, and removes the interval and app-state listener during cleanup. Added source-based tests covering foreground transitions, polling cadence, subscription registration, and teardown.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description explains the change well, but it does not follow the required template or include several required sections.	Reformat the PR body to match the template and add Summary, Screenshots, Testing, AI Review Report, Security Audit, and Notes sections.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: pausing session-screen polling while backgrounded.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

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🧹 Nitpick comments (1)

mobile/src/session/mobile-session-startup-source.test.ts (1)

32-50: 📐 Maintainability & Code Quality | 🔵 Trivial | 🏗️ Heavy lift

Prefer behavioral coverage for the polling lifecycle.

This test only matches source strings, so it cannot detect runtime regressions in AppState gating, listener registration, interval behavior, or cleanup. Extract the polling lifecycle into a small testable helper (or add a runtime harness), and document why source-level testing is required here.

Source: Coding guidelines

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 99905198-2b76-4d1d-9652-2c9a37b92a49

📥 Commits

Reviewing files that changed from the base of the PR and between e600600 and f6eda4c.

📒 Files selected for processing (2)

• mobile/app/h/[hostId]/session/[worktreeId].tsx
• mobile/src/session/mobile-session-startup-source.test.ts