Closes#587. Three coordinated fixes per codex's diagnosis. AcoustID
verification gate left intact — these fixes target the upstream
scanner false-positive surface plus a separate retag-path gap.
Bug 1 — scanner used recordings[0] as authoritative
`core/repair_jobs/acoustid_scanner.py:_scan_file` only checked the
top fingerprint match's metadata. AcoustID often returns multiple
recordings per fingerprint (sample collisions, multi-MB-record
cases) and the wrong-credited recording can outrank the right-
credited one. Foxxify case 2 (Nana / Nana): top match credited the
wrong artist while a lower-ranked candidate matched the user's
expected metadata exactly.
Lifted the verifier's all-candidates check to a shared pure helper
`core/matching/acoustid_candidates.py:find_matching_recording`. Both
verifier and scanner can now ask "given these candidates, does ANY
of them match expected (title, artist)?" with the same contract.
Scanner suppresses the finding when any candidate matches.
Bug 2 — no duration check guards against fingerprint hash collisions
Foxxify case 3: 17-minute mashup edit fingerprinted to a 5-minute
late-70s Japanese hiphop track (different songs, fingerprint hash
collision on a sampled section). Scanner had no signal to detect
this and would have recommended retagging the 17-min file as the
5-min track.
`duration_mismatches_strongly` in the same helper module flags drifts
beyond max(60s, 35%). Scanner now skips findings when the candidate's
duration disagrees strongly with the file's expected duration. Loaded
duration via the existing tracks SQL (added `t.duration` to the
SELECT). Returns False when either side is unknown — no behavior
change for older rows without duration data.
Bug 3 — scanner retag bypassed multi-value ARTISTS tag setting
`core/repair_worker.py:_fix_wrong_song` called `write_tags_to_file`
with single-string artist updates. The writer only wrote TPE1
(single string) and never read the user's
`metadata_enhancement.tags.write_multi_artist` config. Multi-value
ARTISTS tags got stripped on every retag, contradicting the
post-download enrichment pipeline's behavior.
Per codex's pick (option B over routing through enhance_file_metadata),
extended `write_tags_to_file` with an optional `artists_list`
parameter. Each format-specific writer respects the config flag the
same way enrichment.py does:
- ID3: TPE1 stays as joined display string + TXXX:Artists multi-value
- Vorbis/Opus/FLAC: `artist` display string + `artists` multi-value key
- MP4: \xa9ART as list when on, single string when off
Scanner retag derives the per-artist list by splitting AcoustID's
credit through the existing `split_artist_credit` helper (same
separators the matching layer already uses).
Backward compatible: callers that don't pass `artists_list` get the
exact same single-string write as before. No regression for the
write_artist_image button or any other tag_writer caller.
15 tests on the candidate helper + duration guard.
13 tests on the tag_writer multi-value path (write/skip/single/
no-list cases for FLAC + the config-gate helper).
4 new scanner regression tests pinning lower-ranked candidate
suppression, no-suppression when no candidate matches, duration
mismatch skip, no-skip when duration matches.
Existing scanner tests updated for the new 11-column SQL select
(added duration column to fake schema + test row tuples).
Full suite: 3097 passed. Ruff clean.
Broque Thomas
