fix(metadata): normalize artist credits and preserve recording versions

go_backend/title_match_utils.go

@@ -120,8 +120,8 @@ func artistsMatch(expectedArtist, foundArtist string) bool {
 		return true
 	}
 
-	expectedArtists := splitArtists(normExpected)
-	foundArtists := splitArtists(normFound)
+	expectedArtists := splitArtists(expectedArtist)
+	foundArtists := splitArtists(foundArtist)
 
 	for _, expected := range expectedArtists {
 		for _, found := range foundArtists {
@@ -142,20 +142,21 @@ func artistsMatch(expectedArtist, foundArtist string) bool {
 }
 
 func splitArtists(artists string) []string {
-	normalized := artists
+	normalized := strings.ToLower(artists)
 	normalized = strings.ReplaceAll(normalized, " feat. ", "|")
 	normalized = strings.ReplaceAll(normalized, " feat ", "|")
 	normalized = strings.ReplaceAll(normalized, " ft. ", "|")
 	normalized = strings.ReplaceAll(normalized, " ft ", "|")
 	normalized = strings.ReplaceAll(normalized, " & ", "|")
 	normalized = strings.ReplaceAll(normalized, " and ", "|")
-	normalized = strings.ReplaceAll(normalized, ", ", "|")
+	normalized = strings.ReplaceAll(normalized, ",", "|")
+	normalized = strings.ReplaceAll(normalized, ";", "|")
 	normalized = strings.ReplaceAll(normalized, " x ", "|")
 
 	parts := strings.Split(normalized, "|")
 	result := make([]string, 0, len(parts))
 	for _, part := range parts {
-		trimmed := strings.TrimSpace(part)
+		trimmed := normalizeLooseArtistName(part)
 		if trimmed != "" {
 			result = append(result, trimmed)
 		}
@@ -253,6 +254,26 @@ func titlesMatch(expectedTitle, foundTitle string) bool {
 	return false
 }
 
+func trackTitlesMatch(expectedTitle, foundTitle string) bool {
+	expected := normalizeLooseTitle(expectedTitle)
+	found := normalizeLooseTitle(foundTitle)
+	if expected != "" && expected == found {
+		return true
+	}
+
+	// Version words identify recordings; punctuation around them does not.
+	for _, title := range []string{expected, found} {
+		for _, word := range strings.Fields(title) {
+			switch word {
+			case "mix", "remix", "live", "acoustic", "demo", "instrumental",
+				"karaoke", "edit", "extended", "slowed", "sped":
+				return false
+			}
+		}
+	}
+	return titlesMatch(expectedTitle, foundTitle)
+}
+
 func extractCoreTitle(title string) string {
 	parenIdx := strings.Index(title, "(")
 	bracketIdx := strings.Index(title, "[")
@@ -425,7 +446,7 @@ func trackMatchesRequest(req DownloadRequest, resolved resolvedTrackInfo, logPre
 		}
 
 		if req.TrackName != "" && resolved.Title != "" &&
-			!titlesMatch(req.TrackName, resolved.Title) {
+			!trackTitlesMatch(req.TrackName, resolved.Title) {
 			GoLog("[%s] Verification failed: title mismatch — expected '%s', got '%s'\n",
 				logPrefix, req.TrackName, resolved.Title)
 			return false

go_backend/title_match_utils_test.go

@@ -171,6 +171,65 @@ func TestTitlesMatch_SeparatorVariants(t *testing.T) {
 	}
 }
 
+func TestTrackMatchingPreservesArtistCreditBoundaries(t *testing.T) {
+	req := DownloadRequest{
+		TrackName: "Signal - Remix", ArtistName: "Composer, Lead Singer & Lyric Writer",
+		AlbumName: "Original Soundtrack", DurationMS: 234000,
+	}
+	for _, artist := range []string{
+		"Composer, Lead Singer, Guest Writer",
+		"Lead Singer & Composer",
+		"GUEST WRITER; LEAD SINGER",
+	} {
+		t.Run(artist, func(t *testing.T) {
+			resolved := resolvedTrackInfo{
+				Title: "Signal (Remix)", ArtistName: artist,
+				AlbumName: "Original Soundtrack", Duration: 234,
+			}
+			if !trackMatchesRequest(req, resolved, "test") {
+				t.Fatal("matching recording rejected because contributor credits differ")
+			}
+			tracks := []ExtTrackMetadata{{
+				Name: resolved.Title, Artists: artist, AlbumName: "Collection",
+				DurationMS: 234000, ProviderID: "provider",
+			}}
+			if selectBestMetadataEnrichmentTrack(req, tracks) == nil {
+				t.Fatal("matching recording rejected during metadata enrichment")
+			}
+		})
+	}
+}
+
+func TestTrackMetadataTolerancePreservesRecordingIdentity(t *testing.T) {
+	req := DownloadRequest{
+		TrackName: "Signal - Remix", ArtistName: "Composer, Lead Singer & Lyric Writer",
+		AlbumName: "Original Soundtrack", DurationMS: 234000,
+	}
+	for _, tc := range []struct {
+		name     string
+		title    string
+		artist   string
+		duration int
+		want     bool
+	}{
+		{"punctuation", "Signal (Remix)", req.ArtistName, 234, true},
+		{"original", "Signal", req.ArtistName, 234, false},
+		{"named mix", "Signal (Club Mix)", req.ArtistName, 234, false},
+		{"live remix", "Signal (Remix Live)", req.ArtistName, 234, false},
+		{"other artist", "Signal (Remix)", "Unrelated Singer", 234, false},
+		{"other duration", "Signal (Remix)", "Composer, Lead Singer, Guest Writer", 305, false},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			got := trackMatchesRequest(req, resolvedTrackInfo{
+				Title: tc.title, ArtistName: tc.artist, AlbumName: req.AlbumName, Duration: tc.duration,
+			}, "test")
+			if got != tc.want {
+				t.Fatalf("trackMatchesRequest = %v, want %v", got, tc.want)
+			}
+		})
+	}
+}
+
 func TestTitlesMatch_EmojiStrict(t *testing.T) {
 	if titlesMatch("🪐", "Higher Power") {
 		t.Fatal("expected emoji title not to match unrelated textual title")