A bitvid (kind-30078) video with a perfectly playable hosted URL (verified:
archive.org 200 video/mp4 with byte ranges) failed with "No playable source
found." — the video element's src was never even set.
Root cause: the hosted-URL probe (fetch HEAD, mode:no-cors) runs BEFORE src is
assigned, inside the playback-start window — but URL_PROBE_TIMEOUT_MS (4s) is
LONGER than PLAYBACK_START_TIMEOUT (3s). A slow no-cors HEAD (archive.org, and
any host that doesn't answer HEAD fast) consumed the whole start budget, the
withTimeout wrapper aborted the attempt, and the URL was never loaded. A
`<video>` element plays cross-origin URLs WITHOUT CORS anyway, so the fetch
probe was both unnecessary and actively harmful here.
Fix:
- Skip the probe entirely when there's no magnet (URL-only) — nothing to fail
over to, so the video element loads the URL directly. This is the reported
case; verified live: the video now plays (readyState 4, currentTime advancing).
- An ambiguous/error probe no longer VETOES the URL (only a definitively-read
"bad" status deprioritizes it, and even then only when a magnet fallback
exists) — the video element + watchdogs are the real arbiter.
Tests: spec-corrected the always-probe assertion to a dual-source case + added
a URL-only skip-probe test (tests/services/playbackService.test.mjs). 17 pass.
Co-Authored-By: Claude Fable 5 <[email protected]>
