fix(watcher): guard AlarmReceiver finish() with FinishOnce

[TimeToBuildBob]

Problem

AlarmReceiver uses the same goAsync() + finally { pendingResult.finish() } pattern that caused the widget's top Play crash (#360). An OEM pre-finishing the broadcast before the coroutine's finally block throws IllegalStateException("Broadcast already finished"), which escapes the coroutine and kills the process.

This was noted in #360's body:

"Not changed: watcher/AlarmReceiver uses the same goAsync + finally { finish() } pattern, but it has no crash cluster, and putting a time budget on heartbeat parsing changes behavior. It is a candidate for the same helper in a follow-up."

Changes

• Import AsyncBroadcast and wrap pendingResult.finish() with FinishOnce in the LOG_DATA branch of AlarmReceiver
• FinishOnce guards with AtomicBoolean and catches/logs IllegalStateException on the second call — same protection as the widget fix
• No timing budget added: heartbeat parsing has no widget-rendering equivalent, so the existing coroutine lifetime is unchanged

Tests

Adds AlarmReceiverFinishOnceTest with three cases:

• OEM double-finish (IllegalStateException from PendingResult.finish()) does not escape the coroutine
• Normal heartbeat finish completes exactly once
• Exception during heartbeat work still finishes the broadcast

Scope

This is only the FinishOnce guard slice from the task note in ActivityWatch/activitywatch#1435. It does not implement:

• A time budget for heartbeat parsing (deliberate — behavior-change)
• Android missing-key migration for aw-notify.enabled (separate slice)

Closes the follow-up noted in #360.

[greptile-apps]

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge; no new actionable issues remain.

Summary

Guards AlarmReceiver broadcast completion with FinishOnce without adding a time limit to heartbeat work.

• Alarm heartbeats finish through a guard that handles earlier framework completion.

_{Reviews (2) · Last reviewed commit: "test(watcher): exercise production alarm..." · Reviewed by Greptile}

[TimeToBuildBob]

🤖 AI code review

This PR extracts the goAsync() completion path in AlarmReceiver into a new internal function launchAlarmHeartbeats() that wraps the pendingResult.finish() call in AsyncBroadcast.FinishOnce, so a second finish attempt (e.g. from an OEM pre-finishing the broadcast) is caught and logged instead of escaping the coroutine. It also adds a new test file AlarmReceiverFinishOnceTest with three tests covering double-finish, normal finish, and exception-during-work scenarios.

Safe to merge — no P0/P1 findings

Confidence 5/5

✅ No findings. The diff looks correct to me on this pass.

Files changed (2) — the diff as I read it

• mobile/src/main/java/net/activitywatch/android/watcher/AlarmReceiver.kt — Adds launchAlarmHeartbeats() helper that wraps finish() in FinishOnce and uses it in the LOG_DATA branch.
• mobile/src/test/java/net/activitywatch/android/watcher/AlarmReceiverFinishOnceTest.kt — Adds three tests for the new launchAlarmHeartbeats() completion path.

Previous review passes

commit	score	findings	engine	when
82b4b281bd44	4/5	1	llm	2026-10-11 17:42 UTC
48dfd8bcf81f	4/5	2	llm	2026-10-11 18:03 UTC

_{Reviewed 48dfd8bcf81f · openrouter/deepseek/deepseek-v4-flash-0731 · llm engine · 26s · about this reviewer}

_{Maintainer commands}

_{@TimeToBuildBob review (own line) — fresh review · @TimeToBuildBob fix — a worker acts on the findings. Once per comment; 👀 = received.}

[TimeToBuildBob]

@greptileai review

[TimeToBuildBob]

CI-green and mergeable (Greptile 5/5) — waiting only on a maintainer click.

This PR is ready to merge, but the bot has pull-only access to this repo and can't self-merge — surfacing it here so it isn't lost. The monitoring loop will stop re-flagging it now that this note is posted.