Give tracks a source-agnostic identity so the same song from different
sources no longer replays in a loop.
- Canonicalizer resolves (artist, title) to a MusicBrainz recording MBID
(no API key; ~1 req/s, descriptive User-Agent, best-effort). Hits and
confirmed misses are cached in SQLite; transient errors are not.
- Track.key becomes mbid:<id> when resolved, else a normalized
name:<artist>|<title> fallback — still source-agnostic.
- Scheduler now owns the authoritative anti-repeat on the canonical key,
canonicalizing the drawn track with a bounded retry; providers keep a
cheap recent-locator filter to limit retries.
- db: canonical_cache table, history.locator column with migration for
existing databases, recent_locators().
- Canonicalization can be turned off via RADIEO_CANONICAL_ENABLED=0.
Verified: MBID hit/cache/miss, cross-source key collapse, scheduler
dodging a recent play, schema migration, and full stack (Navidrome +
yt-dlp) with zero Python tracebacks and a valid 192 kbps MP3 stream.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Pierre-Olivier Mercier
7e0f08b863