4.8 KiB
PKG-TOOL-THUMB-02 extraction and lifecycle baseline
Started from 0338e0b8b1. No production runtime or
distribution changes. This task reproduces behavior before the resource/module
work in 03 and TS migration in 04. The old default-semantics conflict remains open.
Repeatable controlled tests
yarn test:thumbnail runs the 26 frozen contract assertions and 36 extraction
assertions against recovered CDN 3.5.31 and frozen workspace main/legacy.
The new behavior file also runs in the normal unit/CI command.
Controlled timers and deferred Blob callbacks allow assertions without arbitrary waiting: serial frames, interval clamps/density guards, progress/done ordering, repeat generation, duplicate start/download, pending callback gating, null Blob, late callback after destroy, replacement URLs, missing metadata, changed input, seek setter failure, throwing done/update listeners. These are baseline tests, not assertions that the defects are fixed. Future candidate regression tests must assert corrected resource ownership separately while preserving old evidence.
The old and current implementations leak the first source URL on replacement, retain changed-input listeners and generated wrapper inputs, permit late update after destroy, and leave several callback-failure promises unsettled. Missing metadata rejects with an unbound receiver in 3.5.31; workspace keeps polling even after destruction. Seek-assignment failure rejects correctly in both; a throwing done listener emits error twice in 3.5.31 and once in workspace. Normal progress and PNG URL replacement remain ordered. These distinctions guide 03 fixes.
Actual browser evidence and limitations
Run yarn test:browser test/browser/thumbnail-tool.spec.js test/browser/thumbnail-native.spec.js.
The final 39 rows have zero retries/skips: 24 actual tool scenarios in
Chromium/Firefox, 12 Windows WebKit Blob-unavailable controls, and 3 native
media comparison tests. The 12 controls do not establish successful extraction.
Every control proves that the same file loads in native HTTP video but fails in
native Blob video with media error 4, then reproduces the tool's corresponding
failure and cleanup. If native Blob starts working, the full scenario runs.
Actual scenarios use native file selection, metadata/seek, real canvas.toBlob, PNG decode and non-black opaque pixels. They verify ten updates, two complete generations and normal final URL cleanup. DOM drop dispatch with a real File reproduces the missing listener; calling the existing ondrop method does load. Corrupt media raises a native error without a tool error event; replacement leaks the first URL and a second destroy throws NotFoundError. A captured native PNG callback, delivered after destroy, still emits update and creates an unreleased URL. Only callback delivery is controlled; encoding and media are native.
Initial docs sample testing passed 24 Chromium/Firefox cases and failed all 12 WebKit cases. A second 24-second video-only MP4 probe still failed WebKit. The independent native control then demonstrated HTTP success and Blob failure for the original pattern, looped pattern and docs sample. An exploratory WebM HTTP control did not settle within its 1.5-second observation and is not used to claim codec support. All failed reports and trace directories remain archived. No production media workaround or claimed physical Safari result was introduced.
test/browser/media/thumbnail-pattern.mp4 is a 24-second stream-copy loop of the
existing generated 8-second pattern, needed for the tool's minimum ten samples
and maximum one-sample-per-second density. Reproduce with FFmpeg:
ffmpeg -stream_loop 2 -i test/browser/media/pattern.mp4 -t 24 -an -c:v copy -movflags +faststart test/browser/media/thumbnail-pattern.mp4
The local test server exposes this fixture; no dist or compiled docs files were
edited. Hashes, individual outcomes, measurements, browser versions and CI counts
are in refactor/baselines/thumbnail-behavior-validation.json. The ordinary
browser job discovers the new spec files automatically. No hosted CI run,
coverage improvement, successful WebKit Blob extraction or npm publication is claimed.
Handoff and rollback
03 should own source URLs, generated inputs/listeners, metadata waiting and extraction callbacks; settle pending work on cancellation/error and stop late effects. Keep historical public methods/events and use a documented compatibility policy for delay/height defaults. 04 covers emitter provenance and strict TS; 05 keeps actual Safari/WebKit Blob extraction and old/new core sheet integration open; 06 owns complete installed-package/demo checks. Reverting this task's dedicated commit removes only tests, fixture/server registration, scripts and refactor evidence; it does not roll back production code.