Root cause of the failing downloads: containers usually have no working IPv6 route, but
googlevideo CDN hosts advertise AAAA records, so the downloader tried IPv6 and failed with
'[Errno -5] No address associated with hostname'. Small clips happened to use IPv4; long videos
(more CDN requests / the ffmpeg path) hit IPv6 and died.
- yt-dlp source_address=0.0.0.0 forces IPv4 for every connection (== --force-ipv4). Verified: the
full video+audio download completes cleanly.
- Also: retry (resume) now resets the shared asset from 'error' to 'pending', so it actually
re-downloads — previously the requeued job instantly re-inherited the asset's stale error
because the worker short-circuits a job whose asset already errored.
- Dropped the localdev DNS override (wrong hypothesis; the issue was IPv6, not the resolver).
- Kept yt-dlp retries/fragment_retries/socket_timeout for transient blips.
Verified end-to-end in the worker: two previously-failing long videos now download to done.
Two UAT findings:
1. The device download filename (Content-Disposition) kept emoji/symbols from the video title.
Add storage.display_filename (drops emoji/symbol/control unicode, keeps spaces + accents)
and use it for the download name — readable and clean ("…alapján!.mp4", no emoji).
2. Deleting/canceling a download removed the job but the shared MediaAsset (and its file) lingered
as cache, so 'Ready files' stayed inflated and disk wasn't freed. Rework: _release_asset drops
the hold and, once no job holds the asset, deletes the file + row immediately (the cache only
needs to span overlapping holders). Also fixes cancel never decrementing (it flipped status to
'canceled' before releasing, tripping the holding-state guard).
Verified: filename emoji-stripped; enqueue→delete removes the asset row + file from disk.
