fix: a second copy of a track counts once, joining words don't part two titles, and a newer matcher retries an older one's refusals (M502 #5569)

The second run's refusals were mostly albums holding a track twice (a
two-track single with three files), which no edition can pair, and
release names that differ only in "+" against "/". Tracks are now read
once per disc, number and title, and "and", "&" and "+" count for nothing
when titles are compared; an edition's own title also counts as the
album's name.

library_album_matches records which matcher version decided each album.
Refusals by an older version are matched again, even after the listing is
done, so an improvement reaches them without a migration.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/db/dbq/wanted.sql.go

@@ -20,6 +20,19 @@ func (q *Queries) ClearDefaultReleaseTypeProfile(ctx context.Context) error {
 	return err
 }
 
+const countAlbumsToRematch = `-- name: CountAlbumsToRematch :one
+SELECT COUNT(*) FROM library_album_matches
+ WHERE outcome = 'unmatched' AND matcher < $1::int
+`
+
+// Refusals by an older matcher, which a finished listing goes back to.
+func (q *Queries) CountAlbumsToRematch(ctx context.Context, matcher int32) (int64, error) {
+	row := q.db.QueryRow(ctx, countAlbumsToRematch, matcher)
+	var count int64
+	err := row.Scan(&count)
+	return count, err
+}
+
 const countWants = `-- name: CountWants :one
 SELECT COUNT(*) FILTER (WHERE fulfilled_at IS NULL AND reason <> 'missing')::bigint AS wanted,
        COUNT(*) FILTER (WHERE fulfilled_at IS NULL AND reason = 'missing')::bigint  AS missing,
@@ -126,9 +139,9 @@ func (q *Queries) DeleteWant(ctx context.Context, id pgtype.UUID) (int64, error)
 
 const finishLibraryListing = `-- name: FinishLibraryListing :one
 UPDATE acquisition_settings
-   SET library_listed_at = now(),
+   SET library_listed_at = COALESCE(library_listed_at, now()),
        library_unlisted = (SELECT COUNT(*) FROM library_album_matches WHERE outcome = 'unmatched')
- WHERE id = true AND library_listed_at IS NULL
+ WHERE id = true
 RETURNING library_listed_at, library_unlisted
 `
 
@@ -137,7 +150,8 @@ type FinishLibraryListingRow struct {
 	LibraryUnlisted int32
 }
 
-// The listing is done: count the albums no match was found for.
+// The listing is done, or done again after a newer matcher's retries:
+// count the albums no match was found for. The first finish is kept.
 func (q *Queries) FinishLibraryListing(ctx context.Context) (FinishLibraryListingRow, error) {
 	row := q.db.QueryRow(ctx, finishLibraryListing)
 	var i FinishLibraryListingRow
@@ -405,13 +419,15 @@ SELECT a.id, a.title, a.mbid, a.release_group_mbid, ar.name AS artist_name, ar.m
   JOIN artists ar ON ar.id = a.artist_id
  WHERE a.created_at <= $1::timestamptz
    AND EXISTS (SELECT 1 FROM tracks t WHERE t.album_id = a.id)
-   AND NOT EXISTS (SELECT 1 FROM library_album_matches m WHERE m.album_id = a.id)
+   AND NOT EXISTS (SELECT 1 FROM library_album_matches m
+                    WHERE m.album_id = a.id AND (m.outcome = 'listed' OR m.matcher >= $2::int))
  ORDER BY a.created_at, a.id
- LIMIT $2
+ LIMIT $3
 `
 
 type ListAlbumsToMatchParams struct {
 	Cutoff  pgtype.Timestamptz
+	Matcher int32
 	MaxRows int32
 }
 
@@ -424,11 +440,11 @@ type ListAlbumsToMatchRow struct {
 	ArtistMbid       *string
 }
 
-// Library albums from before the cutoff that the listing has not decided:
-// each is matched to MusicBrainz (#5569). An album row with no tracks is
-// not an album in the library.
+// Library albums from before the cutoff that the listing has not decided,
+// or that an older matcher refused: each is matched to MusicBrainz (#5569).
+// An album row with no tracks is not an album in the library.
 func (q *Queries) ListAlbumsToMatch(ctx context.Context, arg ListAlbumsToMatchParams) ([]ListAlbumsToMatchRow, error) {
-	rows, err := q.db.Query(ctx, listAlbumsToMatch, arg.Cutoff, arg.MaxRows)
+	rows, err := q.db.Query(ctx, listAlbumsToMatch, arg.Cutoff, arg.Matcher, arg.MaxRows)
 	if err != nil {
 		return nil, err
 	}
@@ -937,11 +953,12 @@ func (q *Queries) MarkGroupSeen(ctx context.Context, arg MarkGroupSeenParams) er
 }
 
 const recordAlbumMatch = `-- name: RecordAlbumMatch :exec
-INSERT INTO library_album_matches (album_id, outcome, method, release_group_mbid, detail)
-VALUES ($1, $2, $3, $4, $5)
+INSERT INTO library_album_matches (album_id, outcome, method, release_group_mbid, detail, matcher)
+VALUES ($1, $2, $3, $4, $5,
+        $6)
 ON CONFLICT (album_id) DO UPDATE
-   SET outcome = EXCLUDED.outcome, method = EXCLUDED.method,
-       release_group_mbid = EXCLUDED.release_group_mbid, detail = EXCLUDED.detail, decided_at = now()
+   SET outcome = EXCLUDED.outcome, method = EXCLUDED.method, release_group_mbid = EXCLUDED.release_group_mbid,
+       detail = EXCLUDED.detail, matcher = EXCLUDED.matcher, decided_at = now()
 `
 
 type RecordAlbumMatchParams struct {
@@ -950,6 +967,7 @@ type RecordAlbumMatchParams struct {
 	Method           string
 	ReleaseGroupMbid string
 	Detail           string
+	Matcher          int32
 }
 
 func (q *Queries) RecordAlbumMatch(ctx context.Context, arg RecordAlbumMatchParams) error {
@@ -959,6 +977,7 @@ func (q *Queries) RecordAlbumMatch(ctx context.Context, arg RecordAlbumMatchPara
 		arg.Method,
 		arg.ReleaseGroupMbid,
 		arg.Detail,
+		arg.Matcher,
 	)
 	return err
 }