Symptom 1's 'stuck on first load, fixed by toggling the playlist' is stale
download backoff. On a fresh device the first downloads fail while the link is
settling; DownloadCoordinator escalates an exponential backoff (15s..5min cap),
and ensure() then SKIPS those items. The 60s playlist refresh re-fires
onPlaylistUpdate but ensure() still skips them, and backoff was only ever cleared
by forget() (content-delete) — never by a re-assignment. So the item stays stuck
until the 5-min window happens to lapse; toggling the playlist is just a manual
way to wait it out.
Fix (storm-safe — neither reset fires on the routine same-playlist 60s refresh):
1. DownloadCoordinator.resetBackoff(id) / resetAllBackoff() — clear attempts +
nextAttemptAt but KEEP inFlight (single-flight preserved, no duplicate .part).
2. onPlaylistUpdate resets backoff for each item ONLY when the content-id
signature changed (first load, reassignment, toggle-back), then ensures — so a
genuine (re)assignment retries immediately. Same-signature 60s refresh -> no
reset -> the retry-storm guard stays intact.
3. Network onAvailable (was onLost-only) -> resetAllBackoff() + requestPlaylistRefresh,
so content that failed while the link was settling retries the moment real
connectivity arrives.
Tests: DownloadCoordinatorTest — resetBackoff/resetAllBackoff re-attempt a
backed-off item before the clock advances; existing backoff/single-flight tests
unchanged. :app:testDebugUnitTest green.
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
