fix(android): warn about the 180s record limit only when the last chunk ended early

[thymikee]

Problem

Every chunked Android recording (over 170 s) returned the truncation warning:

Android adb screenrecord stopped before record stop, likely after reaching the 180s platform limit. The MP4 may be truncated; final interactions after the limit are not in the video.

The next chunk recorded those interactions, so the warning was wrong. Seen live on 2026-09-15: a 197 s recording returned chunks and.mp4 (188.6 s) and and.part-002.mp4 (47.9 s), plus both the chunked warning and this limit warning. The bug is on main; #2613 and #2631 did not add it.

Cause

stopOwnedChunks combined every chunk's stopChunk result with OR. Rotation (runtime.ts) starts the next chunk and then stops the previous one. So at record stop, every earlier chunk always reports already-missing, and reachedLimit was always true for a chunked recording.

Fix

stopOwnedChunks now returns the result for the active (last) chunk only. That is the only chunk that must still record at stop. Earlier chunks end because of rotation. The reattach path already used this rule: recovery.ts inspects only chunks.at(-1).

Tests

In chunks.test.ts, both tests go through the live finish path:

• omits the 180s limit warning when only a rotated-out chunk exited before record stop: two chunks, chunk 1 exited (rotation stopped it), chunk 2 still runs at stop. The result has the chunked warning and no limit warning.
• warns about the 180s limit when the last chunk exited before record stop: the only chunk exited before stop, and in a second case chunk 2 of 2 exited before stop. Both results have the warning.

Mutations I ran by hand:

• Put back the OR over all chunks (activeAlreadyExited = alreadyExited || activeAlreadyExited): the omits test fails.
• const active = chunks[0]: the omits test fails.
• return false: the warns test fails. The recovery tests still pass under this mutation because recovery passes its own reachedLimit. The warns test is the only test of the live path.

Live validation

I booted a separate emulator (Pixel_9_Pro_XL_API_37, port 5590, not Pixel_7_CI) and used a source CLI with an isolated state dir. I opened Settings, started record start, scrolled every 10 s, and ran record stop after 218 s.

• Chunks: live.mp4 171.6 s and live.part-002.mp4 39.4 s (ffprobe).
• warning: "Android adb screenrecord is capped at 180s, so this recording was split into multiple MP4 chunks. Android screenrecord encodes a frame only when the screen changes, so this video ends at the last frame it encoded: it covers 211.0s of the 222.6s recording window." The limit warning is not in it.

Checks

pnpm format done. pnpm check:affected --run stops at lint only because of .claude/workflows/agent-device-pr-review.mjs. That file is gitignored, the local harness makes it, and it is not in this diff. I ran each selected gate by hand. All pass: oxlint . --deny-warnings --ignore-pattern '.claude/**', typecheck, check:layering, check:fallow --base origin/main, build, vitest related. The Android recording unit suite passes (85 tests).

[github-actions]

Size Report

Metric	Base	Current	Diff
Installed (including dependencies)	4.57 MB	4.57 MB	+25 B
Package (unpacked)	4.57 MB	4.57 MB	+25 B
Package (download)	1.36 MB	1.36 MB	+14 B

Startup median (7 runs, lower is better):

Scenario	Base	Current	Diff
CLI --version	28.3 ms	28.2 ms	-0.1 ms
CLI --help	79.8 ms	77.7 ms	-2.1 ms

[thymikee]

Reviewed at e736fdd. Clean. stopOwnedChunks now returns the result for the last chunk only, so a chunk that rotation stopped no longer adds the 180s limit warning. The new chunks.test.ts cases cover both the dropped and the kept warning.

The live emulator run in the PR body (218 s, two chunks, no limit warning) exercises this route. All checks pass and there are no conflicts.

[github-actions]

PR Preview Action v1.8.1
Preview removed because the pull request was closed.
2026-09-15 15:36 UTC