Changes the AlbumCoverProvider and ArtistArtProvider interfaces from
MBID-only string parameters to ref-struct signatures so name-based
providers (Deezer, Last.fm in upcoming tasks) can act on rows
without MBIDs.
Today, 53 of 213 artists in the dev DB have NULL MBIDs — featured
artists, remixers, and compilation contributors created from
track-tag splits where the primary-artist MBID is in the file but
collaborator IDs aren't. These rows are unreachable by the current
MBID-only chain. Refactoring the interface unblocks future
name-based providers from acting on them.
TheAudioDB and MBCAA keep MBID-only behavior internally: they return
ErrNotFound when ref.MBID is empty rather than attempting a
name-based fallback. The MBID guard inside EnrichAlbum/EnrichArtist
is removed; providers receive the ref unconditionally and decide
whether they can act on it.
GetAlbumWithFirstTrackPath now JOINs artists to return artist_name
alongside the existing fields, supporting AlbumRef construction.
No behavioral change today (only TheAudioDB + MBCAA registered, both
keep MBID-only behavior). The change unblocks T3 (Deezer) and T4
(Last.fm) which can now register and act on every artist/album
regardless of MBID presence.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
New album-cover and artist-art source implementing
AlbumCoverProvider, ArtistArtProvider, and TestableProvider. Hits
the documented /album-mb.php and /artist-mb.php JSON endpoints by
MBID, then GETs the returned image URLs (CDN, key-less). 2 req/sec
rate limit per the upstream's documented free/test-key tier;
mutex+lastCall serialises ALL HTTP calls regardless of method so
JSON metadata fetches and image GETs share the same budget.
429 / 5xx triggers exponential backoff with jitter (250ms × 2^attempt
± 20%) up to 3 retries before surfacing ErrTransient. 401 / 403
surface as ErrTransient (auth issues are config errors, not "this
album has no art" — the row stays NULL across passes so the operator
sees pending count not decreasing as the diagnostic signal).
Artist art is atomic at the JSON metadata step (one round-trip
yields both URLs); the two image GETs are independent — partial
success returns whatever bytes landed and ErrNotFound only if
neither URL is present in the response.
Configure() falls back to the documented public test key (2) when
the operator's APIKey is empty, per the no-coercive-settings
principle. Test connection hits a stable popular release MBID
(Pink Floyd, "The Dark Side of the Moon").
theAudioDBBaseURL is a var (not const) so tests can override it.
bvandeusen