Follow-up to the album-art resolution fix. That change upgraded MusicBrainz
Cover Art Archive thumbnails (/front-250) to the bare /front original — but
/front redirects to archive.org, which is unreliable: probing release-group
covers showed intermittent HTTP 500s (same URL 500s one second, serves the
next) and multi-MB originals (2.9 MB seen). The result was the user-reported
flakiness: cover art that "sometimes works, sometimes shows nothing", and a
huge image embedded into every track when it did work.
The sized thumbnails (/front-250, -500, -1200) are served by CAA's own CDN,
not the archive.org redirect — which is why /front-250 (240p) was always
reliable. Upgrade to /front-1200 instead: 1200x1200 is a massive jump from
240p, reliably CDN-served, and a sane ~40 KB instead of multi-MB.
Applied in all three CAA spots for consistency: the _upgrade_art_url helper
(embed + cover.jpg paths) and both prefer_caa ("CCA") blocks, which fetched
the bare /front directly with no fallback — so CCA-on users hit the same
flakiness. _fetch_art_bytes still falls back to the original /front-250 if
/front-1200 is ever refused.
Tests updated to assert the 1200px target, idempotency, and that the bare
/front original is intentionally left untouched.
User report: embedded album art came out ~600x600 while the cover.jpg in
the folder was high-res. The cover.jpg path upgraded the source CDN URL
to its highest resolution, but the tag-embed path fetched the raw URL —
so iTunes art embedded at its 600x600 default, Spotify at 640, Deezer at
1000. The "Write Tags to File" retag path had the same gap (Deezer-only
upgrade), and MusicBrainz art was worse still: every Cover Art Archive
URL is built as the /front-250 thumbnail, so MB-sourced downloads
embedded 250x250.
Factor the resolution upgrade + fetch into two shared helpers in
core/metadata/artwork.py and route every art path through them:
_upgrade_art_url(url) — bump to the source's highest resolution:
- Spotify (i.scdn.co) -> original master (~2000px+)
- iTunes (mzstatic.com) -> 3000x3000
- Deezer (dzcdn) -> 1900x1900
- Cover Art Archive -> /front original (was /front-250)
_fetch_art_bytes(url) — upgrade, fetch, and fall back once to the
original size if the CDN refuses the larger one (non-regressive).
Now consistent across: embed-into-tags (post-process), folder cover.jpg
(post-process), and the enhanced-library "Write Tags to File" retag flow.
The YouTube path already upgraded via Album.from_spotify_album, unchanged.
De-duplicates the per-source upgrade code that was copied across sites
and drops the now-unused urllib import from tag_writer.
Not covered (follow-up): Last.fm / Amazon / Tidal / Qobuz have no
explicit upgrade yet — some already serve full-res, others may hand over
a capped size that passes through unchanged.
Tests: new tests/metadata/test_artwork_resolution.py pins every upgrade
(Spotify 300/640->master, iTunes 100/600->3000, Deezer->1900, CAA
thumbnail->original, unrecognized/empty unchanged) and the fetch
fallback. Updated the two tag_writer fallback tests to patch the network
at its new home in artwork.
