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/wanted/library_test.go

@@ -268,7 +268,48 @@ func TestTrackAgreement(t *testing.T) {
 	if _, miss := trackAgreement([]libraryTrack{{Title: "Other", LengthMs: 61000}}, edition, true); miss != `no track of its edition is like "Other" (1:01)` {
 		t.Errorf("unplaced: %q", miss)
 	}
+	if !sameTitle("Brain Stew + Jaded", "Brain Stew / Jaded") || sameTitle("+++", "Grind & Hustle") || sameTitle("Blur", "The Best of Blur") {
+		t.Error("sameTitle: joining words count for nothing, and a title of none is no title")
+	}
+	n := int32(1)
+	copies := tracksToMatch([]dbq.ListAlbumTracksToMatchRow{
+		{Title: "Song", TrackNumber: &n, DurationMs: 1}, {Title: "song", TrackNumber: &n, DurationMs: 2}, {Title: "Other", TrackNumber: &n}})
+	if len(copies) != 2 {
+		t.Errorf("a second copy of a track is read once: %+v", copies)
+	}
 	if agrees(3, 4) || !agrees(4, 5) || agrees(0, 0) {
 		t.Error("agrees: 80% of the album's tracks, and an album has tracks")
 	}
 }
+
+// A refusal by an older matcher is matched again once the matching improves,
+// even after the listing is done; a refusal by this one is not.
+func TestListLibrary_RetriesAnOlderMatchersRefusals_Integration(t *testing.T) {
+	pool := newPool(t)
+	ctx := context.Background()
+	q := dbq.New(pool)
+	s := newService(t, pool, newFakeMB(t))
+	ballad := seedAlbum(t, q, blur, "The Ballad of Darren", "", []string{"The Ballad", "St. Charles Square"})
+	bootleg := seedAlbum(t, q, blur, "Bootleg", "", []string{"Intro"})
+	for _, a := range []pgtype.UUID{ballad.ID, bootleg.ID} {
+		if err := q.RecordAlbumMatch(ctx, dbq.RecordAlbumMatchParams{AlbumID: a, Outcome: "unmatched", Detail: "old", Matcher: 1}); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if _, err := pool.Exec(ctx, `UPDATE library_album_matches SET matcher = $1 WHERE album_id = $2`, libraryMatcher, bootleg.ID); err != nil {
+		t.Fatal(err)
+	}
+	// The reset leaves the listing done.
+	if err := s.listLibrary(ctx, &PassResult{}); err != nil {
+		t.Fatal(err)
+	}
+	if outcome, method, _, _ := matchOf(t, pool, ballad.ID); outcome != "listed" || method != matchDiscography {
+		t.Errorf("the older refusal was decided %s by %s", outcome, method)
+	}
+	if _, _, _, detail := matchOf(t, pool, bootleg.ID); detail != "old" {
+		t.Errorf("this matcher's own refusal was retried: %q", detail)
+	}
+	if state, _ := q.GetLibraryListing(ctx); state.LibraryUnlisted != 1 {
+		t.Errorf("unlisted = %d, want the bootleg alone", state.LibraryUnlisted)
+	}
+}