chore: bump app version to v4.2.1

.github/workflows/release.yml

@@ -164,13 +164,18 @@ jobs:
           path: build/app/outputs/flutter-apk/SpotiFLAC-*.apk
 
   build-ios:
-    runs-on: macos-latest
+    runs-on: macos-15
     needs: get-version # Only depends on version, NOT android build!
 
     steps:
       - name: Checkout repository
         uses: actions/checkout@v6
 
+      - name: Select Xcode 26.1.1
+        run: |
+          sudo xcode-select -s /Applications/Xcode_26.1.1.app
+          xcodebuild -version
+
       - name: Setup Go
         uses: actions/setup-go@v6
         with:

android/app/build.gradle.kts

@@ -57,6 +57,18 @@ android {
     }
 
     buildTypes {
+        getByName("debug") {
+            ndk {
+                debugSymbolLevel = "FULL"
+            }
+        }
+
+        getByName("profile") {
+            ndk {
+                debugSymbolLevel = "FULL"
+            }
+        }
+
         release {
             // For local builds: use release signing if key.properties exists
             // For CI builds: APK is signed by GitHub Action after build
@@ -71,6 +83,9 @@ android {
                 getDefaultProguardFile("proguard-android-optimize.txt"),
                 "proguard-rules.pro"
             )
+            ndk {
+                debugSymbolLevel = "FULL"
+            }
         }
     }
     

android/app/src/main/AndroidManifest.xml

@@ -94,24 +94,6 @@
             android:exported="false"
             android:foregroundServiceType="dataSync" />
 
-        <!-- Audio playback service for media notification / background audio -->
-        <service
-            android:name="com.ryanheise.audioservice.AudioService"
-            android:exported="true"
-            android:foregroundServiceType="mediaPlayback">
-            <intent-filter>
-                <action android:name="android.media.browse.MediaBrowserService" />
-            </intent-filter>
-        </service>
-
-        <receiver
-            android:name="com.ryanheise.audioservice.MediaButtonReceiver"
-            android:exported="true">
-            <intent-filter>
-                <action android:name="android.intent.action.MEDIA_BUTTON" />
-            </intent-filter>
-        </receiver>
-
         <!-- flutter_local_notifications receivers -->
         <receiver android:exported="false" android:name="com.dexterous.flutterlocalnotifications.ScheduledNotificationReceiver" />
         <receiver android:exported="false" android:name="com.dexterous.flutterlocalnotifications.ScheduledNotificationBootReceiver">

go_backend/ape_tags.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"io"
 	"os"
-	"strconv"
 	"strings"
 )
 
@@ -367,12 +366,9 @@ func APETagToAudioMetadata(tag *APETag) *AudioMetadata {
 		case "DATE":
 			metadata.Date = value
 		case "TRACK", "TRACKNUMBER":
-			// APE track format can be "3" or "3/12"
+			metadata.TrackNumber, metadata.TotalTracks = parseIndexPair(value)
-			trackNum, _ := strconv.Atoi(strings.Split(value, "/")[0])
-			metadata.TrackNumber = trackNum
 		case "DISC", "DISCNUMBER":
-			discNum, _ := strconv.Atoi(strings.Split(value, "/")[0])
+			metadata.DiscNumber, metadata.TotalDiscs = parseIndexPair(value)
-			metadata.DiscNumber = discNum
 		case "ISRC":
 			metadata.ISRC = value
 		case "LYRICS", "UNSYNCEDLYRICS":
@@ -425,10 +421,10 @@ func AudioMetadataToAPEItems(metadata *AudioMetadata) []APETagItem {
 		addItem("Year", metadata.Year)
 	}
 	if metadata.TrackNumber > 0 {
-		addItem("Track", strconv.Itoa(metadata.TrackNumber))
+		addItem("Track", formatIndexValue(metadata.TrackNumber, metadata.TotalTracks))
 	}
 	if metadata.DiscNumber > 0 {
-		addItem("Disc", strconv.Itoa(metadata.DiscNumber))
+		addItem("Disc", formatIndexValue(metadata.DiscNumber, metadata.TotalDiscs))
 	}
 	addItem("ISRC", metadata.ISRC)
 	addItem("Lyrics", metadata.Lyrics)
@@ -453,7 +449,7 @@ func apeKeysFromFields(fields map[string]string) map[string]struct{} {
 		"artist":                "ARTIST",
 		"album":                 "ALBUM",
 		"album_artist":          "ALBUM ARTIST",
-		"date":                  "YEAR",
+		"date":                  "DATE",
 		"genre":                 "GENRE",
 		"track_number":          "TRACK",
 		"disc_number":           "DISC",
@@ -475,7 +471,7 @@ func apeKeysFromFields(fields map[string]string) map[string]struct{} {
 		}
 	}
 	// Some fields have reader aliases that must also be cleared when the
-	// canonical key is updated (e.g. "Year" writer ↔ DATE/YEAR reader,
+	// canonical key is updated (e.g. DATE writer ↔ DATE/YEAR reader,
 	// DISC ↔ DISCNUMBER, TRACK ↔ TRACKNUMBER, "ALBUM ARTIST" ↔ ALBUMARTIST,
 	// LABEL ↔ PUBLISHER, LYRICS ↔ UNSYNCEDLYRICS).
 	if _, present := fields["date"]; present {
@@ -484,9 +480,15 @@ func apeKeysFromFields(fields map[string]string) map[string]struct{} {
 	if _, present := fields["disc_number"]; present {
 		result["DISCNUMBER"] = struct{}{}
 	}
+	if _, present := fields["disc_total"]; present {
+		result["DISCNUMBER"] = struct{}{}
+	}
 	if _, present := fields["track_number"]; present {
 		result["TRACKNUMBER"] = struct{}{}
 	}
+	if _, present := fields["track_total"]; present {
+		result["TRACKNUMBER"] = struct{}{}
+	}
 	if _, present := fields["album_artist"]; present {
 		result["ALBUMARTIST"] = struct{}{}
 	}

go_backend/audio_metadata.go

@@ -21,7 +21,9 @@ type AudioMetadata struct {
 	Year        string
 	Date        string
 	TrackNumber int
+	TotalTracks int
 	DiscNumber  int
+	TotalDiscs  int
 	ISRC        string
 	Lyrics      string
 	Label       string
@@ -173,9 +175,9 @@ func parseID3v22Frames(data []byte, metadata *AudioMetadata, tagUnsync bool) {
 		case "TCO":
 			metadata.Genre = cleanGenre(value)
 		case "TRK":
-			metadata.TrackNumber = parseTrackNumber(value)
+			metadata.TrackNumber, metadata.TotalTracks = parseIndexPair(value)
 		case "TPA":
-			metadata.DiscNumber = parseTrackNumber(value)
+			metadata.DiscNumber, metadata.TotalDiscs = parseIndexPair(value)
 		case "TCM":
 			metadata.Composer = value
 		case "TPB":
@@ -292,9 +294,9 @@ func parseID3v23Frames(data []byte, metadata *AudioMetadata, version byte, tagUn
 		case "TCON":
 			metadata.Genre = cleanGenre(value)
 		case "TRCK":
-			metadata.TrackNumber = parseTrackNumber(value)
+			metadata.TrackNumber, metadata.TotalTracks = parseIndexPair(value)
 		case "TPOS":
-			metadata.DiscNumber = parseTrackNumber(value)
+			metadata.DiscNumber, metadata.TotalDiscs = parseIndexPair(value)
 		case "TSRC":
 			metadata.ISRC = value
 		case "TCOM":
@@ -580,14 +582,28 @@ func cleanGenre(genre string) string {
 }
 
 func parseTrackNumber(s string) int {
-	s = strings.TrimSpace(s)
+	num, _ := parseIndexPair(s)
-	if idx := strings.Index(s, "/"); idx > 0 {
-		s = s[:idx]
-	}
-	num, _ := strconv.Atoi(s)
 	return num
 }
 
+func parseIndexPair(s string) (int, int) {
+	s = strings.TrimSpace(s)
+	if s == "" {
+		return 0, 0
+	}
+
+	first := s
+	second := ""
+	if idx := strings.Index(s, "/"); idx > 0 {
+		first = s[:idx]
+		second = s[idx+1:]
+	}
+
+	num, _ := strconv.Atoi(strings.TrimSpace(first))
+	total, _ := strconv.Atoi(strings.TrimSpace(second))
+	return num, total
+}
+
 func removeUnsync(data []byte) []byte {
 	if len(data) == 0 {
 		return data
@@ -1037,9 +1053,9 @@ func parseVorbisComments(data []byte, metadata *AudioMetadata) {
 		case "GENRE":
 			metadata.Genre = value
 		case "TRACKNUMBER", "TRACK":
-			metadata.TrackNumber = parseTrackNumber(value)
+			metadata.TrackNumber, metadata.TotalTracks = parseIndexPair(value)
 		case "DISCNUMBER", "DISC":
-			metadata.DiscNumber = parseTrackNumber(value)
+			metadata.DiscNumber, metadata.TotalDiscs = parseIndexPair(value)
 		case "ISRC":
 			metadata.ISRC = value
 		case "COMPOSER":

go_backend/cue_parser.go

@@ -513,6 +513,11 @@ func scanCueSheetForLibrary(cuePath string, sheet *CueSheet, audioPath, virtualP
 			album = "Unknown Album"
 		}
 
+		composer := track.Composer
+		if composer == "" {
+			composer = sheet.Composer
+		}
+
 		var duration int
 		if i+1 < len(sheet.Tracks) {
 			nextStart := sheet.Tracks[i+1].StartTime
@@ -539,12 +544,15 @@ func scanCueSheetForLibrary(cuePath string, sheet *CueSheet, audioPath, virtualP
 			ScannedAt:   scanTime,
 			ISRC:        track.ISRC,
 			TrackNumber: track.Number,
+			TotalTracks: len(sheet.Tracks),
 			DiscNumber:  1,
+			TotalDiscs:  1,
 			Duration:    duration,
 			ReleaseDate: sheet.Date,
 			BitDepth:    bitDepth,
 			SampleRate:  sampleRate,
 			Genre:       sheet.Genre,
+			Composer:    composer,
 			Format:      "cue+" + strings.TrimPrefix(audioExt, "."),
 		}
 

go_backend/deezer.go

@@ -630,6 +630,12 @@ func (c *DeezerClient) GetAlbum(ctx context.Context, albumID string) (*AlbumResp
 	}
 
 	isrcMap := c.fetchISRCsParallel(ctx, allTracks)
+	totalDiscs := 0
+	for _, track := range allTracks {
+		if track.DiskNumber > totalDiscs {
+			totalDiscs = track.DiskNumber
+		}
+	}
 
 	tracks := make([]AlbumTrackMetadata, 0, len(allTracks))
 	albumType := album.RecordType
@@ -658,6 +664,7 @@ func (c *DeezerClient) GetAlbum(ctx context.Context, albumID string) (*AlbumResp
 			TrackNumber: trackNum,
 			TotalTracks: album.NbTracks,
 			DiscNumber:  track.DiskNumber,
+			TotalDiscs:  totalDiscs,
 			ExternalURL: track.Link,
 			ISRC:        isrc,
 			AlbumID:     fmt.Sprintf("deezer:%d", album.ID),

go_backend/deezer_download.go

@@ -369,10 +369,12 @@ func downloadFromDeezer(req DownloadRequest) (DeezerDownloadResult, error) {
 		TrackNumber:   req.TrackNumber,
 		TotalTracks:   req.TotalTracks,
 		DiscNumber:    req.DiscNumber,
+		TotalDiscs:    req.TotalDiscs,
 		ISRC:          req.ISRC,
 		Genre:         req.Genre,
 		Label:         req.Label,
 		Copyright:     req.Copyright,
+		Composer:      req.Composer,
 	}
 
 	var coverData []byte

go_backend/exports.go

@@ -55,6 +55,7 @@ type DownloadRequest struct {
 	TrackNumber          int    `json:"track_number"`
 	DiscNumber           int    `json:"disc_number"`
 	TotalTracks          int    `json:"total_tracks"`
+	TotalDiscs           int    `json:"total_discs,omitempty"`
 	ReleaseDate          string `json:"release_date"`
 	ItemID               string `json:"item_id"`
 	DurationMS           int    `json:"duration_ms"`
@@ -62,6 +63,7 @@ type DownloadRequest struct {
 	Genre                string `json:"genre,omitempty"`
 	Label                string `json:"label,omitempty"`
 	Copyright            string `json:"copyright,omitempty"`
+	Composer             string `json:"composer,omitempty"`
 	TidalID              string `json:"tidal_id,omitempty"`
 	QobuzID              string `json:"qobuz_id,omitempty"`
 	DeezerID             string `json:"deezer_id,omitempty"`
@@ -88,11 +90,14 @@ type DownloadResponse struct {
 	ReleaseDate            string `json:"release_date,omitempty"`
 	TrackNumber            int    `json:"track_number,omitempty"`
 	DiscNumber             int    `json:"disc_number,omitempty"`
+	TotalTracks            int    `json:"total_tracks,omitempty"`
+	TotalDiscs             int    `json:"total_discs,omitempty"`
 	ISRC                   string `json:"isrc,omitempty"`
 	CoverURL               string `json:"cover_url,omitempty"`
 	Genre                  string `json:"genre,omitempty"`
 	Label                  string `json:"label,omitempty"`
 	Copyright              string `json:"copyright,omitempty"`
+	Composer               string `json:"composer,omitempty"`
 	SkipMetadataEnrichment bool   `json:"skip_metadata_enrichment,omitempty"`
 	LyricsLRC              string `json:"lyrics_lrc,omitempty"`
 	DecryptionKey          string `json:"decryption_key,omitempty"`
@@ -107,12 +112,15 @@ type DownloadResult struct {
 	Album         string
 	ReleaseDate   string
 	TrackNumber   int
+	TotalTracks   int
 	DiscNumber    int
+	TotalDiscs    int
 	ISRC          string
 	CoverURL      string
 	Genre         string
 	Label         string
 	Copyright     string
+	Composer      string
 	LyricsLRC     string
 	DecryptionKey string
 }
@@ -130,11 +138,14 @@ type reEnrichRequest struct {
 	AlbumArtist   string   `json:"album_artist"`
 	TrackNumber   int      `json:"track_number"`
 	DiscNumber    int      `json:"disc_number"`
+	TotalTracks   int      `json:"total_tracks,omitempty"`
+	TotalDiscs    int      `json:"total_discs,omitempty"`
 	ReleaseDate   string   `json:"release_date"`
 	ISRC          string   `json:"isrc"`
 	Genre         string   `json:"genre"`
 	Label         string   `json:"label"`
 	Copyright     string   `json:"copyright"`
+	Composer      string   `json:"composer"`
 	DurationMs    int64    `json:"duration_ms"`
 	SearchOnline  bool     `json:"search_online"`
 	UpdateFields  []string `json:"update_fields,omitempty"`
@@ -183,9 +194,15 @@ func applyReEnrichTrackMetadata(req *reEnrichRequest, track ExtTrackMetadata) {
 		if track.TrackNumber > 0 {
 			req.TrackNumber = track.TrackNumber
 		}
+		if track.TotalTracks > 0 {
+			req.TotalTracks = track.TotalTracks
+		}
 		if track.DiscNumber > 0 {
 			req.DiscNumber = track.DiscNumber
 		}
+		if track.TotalDiscs > 0 {
+			req.TotalDiscs = track.TotalDiscs
+		}
 	}
 	if req.shouldUpdateField("release_info") {
 		if track.ReleaseDate != "" {
@@ -213,6 +230,9 @@ func applyReEnrichTrackMetadata(req *reEnrichRequest, track ExtTrackMetadata) {
 		if track.Copyright != "" {
 			req.Copyright = track.Copyright
 		}
+		if track.Composer != "" {
+			req.Composer = track.Composer
+		}
 	}
 }
 
@@ -225,6 +245,11 @@ func reEnrichDownloadRequest(req reEnrichRequest) DownloadRequest {
 		ISRC:          req.ISRC,
 		DurationMS:    int(req.DurationMs),
 		ArtistTagMode: req.ArtistTagMode,
+		TrackNumber:   req.TrackNumber,
+		TotalTracks:   req.TotalTracks,
+		DiscNumber:    req.DiscNumber,
+		TotalDiscs:    req.TotalDiscs,
+		Composer:      req.Composer,
 	}
 }
 
@@ -256,13 +281,16 @@ func buildReEnrichFFmpegMetadata(req *reEnrichRequest, lyricsLRC string) map[str
 		if req.Copyright != "" {
 			metadata["COPYRIGHT"] = req.Copyright
 		}
+		if req.Composer != "" {
+			metadata["COMPOSER"] = req.Composer
+		}
 	}
 	if req.shouldUpdateField("track_info") {
 		if req.TrackNumber > 0 {
-			metadata["TRACKNUMBER"] = fmt.Sprintf("%d", req.TrackNumber)
+			metadata["TRACKNUMBER"] = formatIndexValue(req.TrackNumber, req.TotalTracks)
 		}
 		if req.DiscNumber > 0 {
-			metadata["DISCNUMBER"] = fmt.Sprintf("%d", req.DiscNumber)
+			metadata["DISCNUMBER"] = formatIndexValue(req.DiscNumber, req.TotalDiscs)
 		}
 	}
 	if req.shouldUpdateField("lyrics") {
@@ -367,11 +395,14 @@ func extTrackFromTrackMetadata(track *TrackMetadata, providerID string) *ExtTrac
 		Images:      track.Images,
 		ReleaseDate: track.ReleaseDate,
 		TrackNumber: track.TrackNumber,
+		TotalTracks: track.TotalTracks,
 		DiscNumber:  track.DiscNumber,
+		TotalDiscs:  track.TotalDiscs,
 		ISRC:        track.ISRC,
 		ProviderID:  providerID,
 		DeezerID:    deezerID,
 		SpotifyID:   track.SpotifyID,
+		Composer:    track.Composer,
 	}
 }
 
@@ -533,6 +564,11 @@ func buildDownloadSuccessResponse(
 		copyright = req.Copyright
 	}
 
+	composer := result.Composer
+	if composer == "" {
+		composer = req.Composer
+	}
+
 	coverURL := strings.TrimSpace(result.CoverURL)
 	if coverURL == "" {
 		coverURL = strings.TrimSpace(req.CoverURL)
@@ -552,12 +588,15 @@ func buildDownloadSuccessResponse(
 		AlbumArtist:      req.AlbumArtist,
 		ReleaseDate:      releaseDate,
 		TrackNumber:      trackNumber,
+		TotalTracks:      req.TotalTracks,
 		DiscNumber:       discNumber,
+		TotalDiscs:       req.TotalDiscs,
 		ISRC:             isrc,
 		CoverURL:         coverURL,
 		Genre:            genre,
 		Label:            label,
 		Copyright:        copyright,
+		Composer:         composer,
 		LyricsLRC:        result.LyricsLRC,
 		DecryptionKey:    result.DecryptionKey,
 	}
@@ -1005,7 +1044,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 		"album_artist": "",
 		"date":         "",
 		"track_number": 0,
+		"total_tracks": 0,
 		"disc_number":  0,
+		"total_discs":  0,
 		"isrc":         "",
 		"lyrics":       "",
 		"genre":        "",
@@ -1033,7 +1074,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 					result["date"] = oggMeta.Year
 				}
 				result["track_number"] = oggMeta.TrackNumber
+				result["total_tracks"] = oggMeta.TotalTracks
 				result["disc_number"] = oggMeta.DiscNumber
+				result["total_discs"] = oggMeta.TotalDiscs
 				result["isrc"] = oggMeta.ISRC
 				result["lyrics"] = oggMeta.Lyrics
 				result["genre"] = oggMeta.Genre
@@ -1054,7 +1097,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 			result["album_artist"] = metadata.AlbumArtist
 			result["date"] = metadata.Date
 			result["track_number"] = metadata.TrackNumber
+			result["total_tracks"] = metadata.TotalTracks
 			result["disc_number"] = metadata.DiscNumber
+			result["total_discs"] = metadata.TotalDiscs
 			result["isrc"] = metadata.ISRC
 			result["lyrics"] = metadata.Lyrics
 			result["genre"] = metadata.Genre
@@ -1088,7 +1133,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 				result["date"] = meta.Year
 			}
 			result["track_number"] = meta.TrackNumber
+			result["total_tracks"] = meta.TotalTracks
 			result["disc_number"] = meta.DiscNumber
+			result["total_discs"] = meta.TotalDiscs
 			result["isrc"] = meta.ISRC
 			result["lyrics"] = meta.Lyrics
 			result["genre"] = meta.Genre
@@ -1118,7 +1165,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 				result["date"] = meta.Year
 			}
 			result["track_number"] = meta.TrackNumber
+			result["total_tracks"] = meta.TotalTracks
 			result["disc_number"] = meta.DiscNumber
+			result["total_discs"] = meta.TotalDiscs
 			result["isrc"] = meta.ISRC
 			result["lyrics"] = meta.Lyrics
 			result["genre"] = meta.Genre
@@ -1149,7 +1198,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 				result["date"] = meta.Year
 			}
 			result["track_number"] = meta.TrackNumber
+			result["total_tracks"] = meta.TotalTracks
 			result["disc_number"] = meta.DiscNumber
+			result["total_discs"] = meta.TotalDiscs
 			result["isrc"] = meta.ISRC
 			result["lyrics"] = meta.Lyrics
 			result["genre"] = meta.Genre
@@ -1182,7 +1233,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 					result["date"] = meta.Year
 				}
 				result["track_number"] = meta.TrackNumber
+				result["total_tracks"] = meta.TotalTracks
 				result["disc_number"] = meta.DiscNumber
+				result["total_discs"] = meta.TotalDiscs
 				result["isrc"] = meta.ISRC
 				result["lyrics"] = meta.Lyrics
 				result["genre"] = meta.Genre
@@ -1281,13 +1334,21 @@ func EditFileMetadata(filePath, metadataJSON string) (string, error) {
 	// APE/WV/MPC: write APEv2 tags natively
 	if isApeFile {
 		trackNum := 0
+		totalTracks := 0
 		discNum := 0
+		totalDiscs := 0
 		if v, ok := fields["track_number"]; ok && v != "" {
 			fmt.Sscanf(v, "%d", &trackNum)
 		}
+		if v, ok := fields["track_total"]; ok && v != "" {
+			fmt.Sscanf(v, "%d", &totalTracks)
+		}
 		if v, ok := fields["disc_number"]; ok && v != "" {
 			fmt.Sscanf(v, "%d", &discNum)
 		}
+		if v, ok := fields["disc_total"]; ok && v != "" {
+			fmt.Sscanf(v, "%d", &totalDiscs)
+		}
 
 		meta := &AudioMetadata{
 			Title:               fields["title"],
@@ -1296,7 +1357,9 @@ func EditFileMetadata(filePath, metadataJSON string) (string, error) {
 			AlbumArtist:         fields["album_artist"],
 			Date:                fields["date"],
 			TrackNumber:         trackNum,
+			TotalTracks:         totalTracks,
 			DiscNumber:          discNum,
+			TotalDiscs:          totalDiscs,
 			ISRC:                fields["isrc"],
 			Genre:               fields["genre"],
 			Label:               fields["label"],
@@ -1930,11 +1993,13 @@ func buildDeezerISRCSearchResult(track *TrackMetadata) map[string]interface{} {
 		"track_number":  track.TrackNumber,
 		"total_tracks":  track.TotalTracks,
 		"disc_number":   track.DiscNumber,
+		"total_discs":   track.TotalDiscs,
 		"external_urls": track.ExternalURL,
 		"isrc":          track.ISRC,
 		"album_id":      track.AlbumID,
 		"artist_id":     track.ArtistID,
 		"album_type":    track.AlbumType,
+		"composer":      track.Composer,
 	}
 
 	if deezerID := strings.TrimSpace(strings.TrimPrefix(track.SpotifyID, "deezer:")); deezerID != "" {
@@ -2237,7 +2302,7 @@ func ReEnrichFile(requestJSON string) (string, error) {
 
 		deezerClient := GetDeezerClient()
 		GoLog("[ReEnrich] Trying metadata providers in configured priority...\n")
-		manager := GetExtensionManager()
+		manager := getExtensionManager()
 		if identifierTrack, err := resolveReEnrichTrackFromIdentifiers(req); err == nil && identifierTrack != nil {
 			GoLog("[ReEnrich] Identifier-first metadata match (%s): %s - %s (album: %s, date: %s)\n",
 				identifierTrack.ProviderID, identifierTrack.Name, identifierTrack.Artists, identifierTrack.AlbumName, identifierTrack.ReleaseDate)
@@ -2379,7 +2444,9 @@ func ReEnrichFile(requestJSON string) (string, error) {
 	}
 	if req.shouldUpdateField("track_info") {
 		enrichedMeta["track_number"] = req.TrackNumber
+		enrichedMeta["total_tracks"] = req.TotalTracks
 		enrichedMeta["disc_number"] = req.DiscNumber
+		enrichedMeta["total_discs"] = req.TotalDiscs
 	}
 	if req.shouldUpdateField("release_info") {
 		enrichedMeta["release_date"] = req.ReleaseDate
@@ -2392,6 +2459,7 @@ func ReEnrichFile(requestJSON string) (string, error) {
 		enrichedMeta["genre"] = req.Genre
 		enrichedMeta["label"] = req.Label
 		enrichedMeta["copyright"] = req.Copyright
+		enrichedMeta["composer"] = req.Composer
 	}
 
 	if isFlac {
@@ -2408,7 +2476,9 @@ func ReEnrichFile(requestJSON string) (string, error) {
 		}
 		if req.shouldUpdateField("track_info") {
 			metadata.TrackNumber = req.TrackNumber
+			metadata.TotalTracks = req.TotalTracks
 			metadata.DiscNumber = req.DiscNumber
+			metadata.TotalDiscs = req.TotalDiscs
 		}
 		if req.shouldUpdateField("release_info") {
 			metadata.Date = req.ReleaseDate
@@ -2421,6 +2491,7 @@ func ReEnrichFile(requestJSON string) (string, error) {
 			metadata.Genre = req.Genre
 			metadata.Label = req.Label
 			metadata.Copyright = req.Copyright
+			metadata.Composer = req.Composer
 		}
 
 		if len(coverDataBytes) > 0 {
@@ -2471,7 +2542,7 @@ func ReEnrichFile(requestJSON string) (string, error) {
 }
 
 func InitExtensionSystem(extensionsDir, dataDir string) error {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	if err := manager.SetDirectories(extensionsDir, dataDir); err != nil {
 		return err
 	}
@@ -2485,7 +2556,7 @@ func InitExtensionSystem(extensionsDir, dataDir string) error {
 }
 
 func LoadExtensionsFromDir(dirPath string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	loaded, errors := manager.LoadExtensionsFromDirectory(dirPath)
 
 	result := map[string]interface{}{
@@ -2506,7 +2577,7 @@ func LoadExtensionsFromDir(dirPath string) (string, error) {
 }
 
 func LoadExtensionFromPath(filePath string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.LoadExtensionFromFile(filePath)
 	if err != nil {
 		return "", err
@@ -2529,17 +2600,17 @@ func LoadExtensionFromPath(filePath string) (string, error) {
 }
 
 func UnloadExtensionByID(extensionID string) error {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	return manager.UnloadExtension(extensionID)
 }
 
 func RemoveExtensionByID(extensionID string) error {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	return manager.RemoveExtension(extensionID)
 }
 
 func UpgradeExtensionFromPath(filePath string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.UpgradeExtension(filePath)
 	if err != nil {
 		return "", err
@@ -2561,17 +2632,17 @@ func UpgradeExtensionFromPath(filePath string) (string, error) {
 }
 
 func CheckExtensionUpgradeFromPath(filePath string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	return manager.CheckExtensionUpgradeJSON(filePath)
 }
 
 func GetInstalledExtensions() (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	return manager.GetInstalledExtensionsJSON()
 }
 
 func SetExtensionEnabledByID(extensionID string, enabled bool) error {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	return manager.SetExtensionEnabled(extensionID, enabled)
 }
 
@@ -2636,12 +2707,12 @@ func SetExtensionSettingsJSON(extensionID, settingsJSON string) error {
 		return err
 	}
 
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	return manager.InitializeExtension(extensionID, settings)
 }
 
 func SearchTracksWithExtensionsJSON(query string, limit int) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	tracks, err := manager.SearchTracksWithExtensions(query, limit)
 	if err != nil {
 		return "", err
@@ -2656,7 +2727,7 @@ func SearchTracksWithExtensionsJSON(query string, limit int) (string, error) {
 }
 
 func SearchTracksWithMetadataProvidersJSON(query string, limit int, includeExtensions bool) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	tracks, err := manager.SearchTracksWithMetadataProviders(query, limit, includeExtensions)
 	if err != nil {
 		return "", err
@@ -2703,12 +2774,12 @@ func DownloadWithExtensionsJSON(requestJSON string) (string, error) {
 }
 
 func CleanupExtensions() {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	manager.UnloadAllExtensions()
 }
 
 func InvokeExtensionActionJSON(extensionID, actionName string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	result, err := manager.InvokeAction(extensionID, actionName)
 	if err != nil {
 		return "", err
@@ -2845,7 +2916,7 @@ func GetAllPendingFFmpegCommandsJSON() (string, error) {
 }
 
 func EnrichTrackWithExtensionJSON(extensionID, trackJSON string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.GetExtension(extensionID)
 	if err != nil {
 		return trackJSON, nil
@@ -2860,7 +2931,7 @@ func EnrichTrackWithExtensionJSON(extensionID, trackJSON string) (string, error)
 		return trackJSON, fmt.Errorf("failed to parse track: %w", err)
 	}
 
-	provider := NewExtensionProviderWrapper(ext)
+	provider := newExtensionProviderWrapper(ext)
 	enrichedTrack, err := provider.EnrichTrack(&track)
 	if err != nil {
 		return trackJSON, nil
@@ -2875,7 +2946,7 @@ func EnrichTrackWithExtensionJSON(extensionID, trackJSON string) (string, error)
 }
 
 func CustomSearchWithExtensionJSON(extensionID, query string, optionsJSON string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.GetExtension(extensionID)
 	if err != nil {
 		return "", err
@@ -2892,7 +2963,7 @@ func CustomSearchWithExtensionJSON(extensionID, query string, optionsJSON string
 		}
 	}
 
-	provider := NewExtensionProviderWrapper(ext)
+	provider := newExtensionProviderWrapper(ext)
 	tracks, err := provider.CustomSearch(query, options)
 	if err != nil {
 		return "", err
@@ -2910,11 +2981,14 @@ func CustomSearchWithExtensionJSON(extensionID, query string, optionsJSON string
 			"images":       track.ResolvedCoverURL(),
 			"release_date": track.ReleaseDate,
 			"track_number": track.TrackNumber,
+			"total_tracks": track.TotalTracks,
 			"disc_number":  track.DiscNumber,
+			"total_discs":  track.TotalDiscs,
 			"isrc":         track.ISRC,
 			"provider_id":  track.ProviderID,
 			"item_type":    track.ItemType,
 			"album_type":   track.AlbumType,
+			"composer":     track.Composer,
 		}
 	}
 
@@ -2927,7 +3001,7 @@ func CustomSearchWithExtensionJSON(extensionID, query string, optionsJSON string
 }
 
 func GetSearchProvidersJSON() (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	providers := manager.GetSearchProviders()
 
 	result := make([]map[string]interface{}, 0, len(providers))
@@ -2950,7 +3024,7 @@ func GetSearchProvidersJSON() (string, error) {
 }
 
 func HandleURLWithExtensionJSON(url string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	resultWithID, err := manager.HandleURLWithExtension(url)
 	if err != nil {
 		return "", err
@@ -2981,9 +3055,12 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 			"images":       result.Track.ResolvedCoverURL(),
 			"release_date": result.Track.ReleaseDate,
 			"track_number": result.Track.TrackNumber,
+			"total_tracks": result.Track.TotalTracks,
 			"disc_number":  result.Track.DiscNumber,
+			"total_discs":  result.Track.TotalDiscs,
 			"isrc":         result.Track.ISRC,
 			"provider_id":  result.Track.ProviderID,
+			"composer":     result.Track.Composer,
 		}
 	}
 
@@ -3000,11 +3077,14 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 				"images":       track.ResolvedCoverURL(),
 				"release_date": track.ReleaseDate,
 				"track_number": track.TrackNumber,
+				"total_tracks": track.TotalTracks,
 				"disc_number":  track.DiscNumber,
+				"total_discs":  track.TotalDiscs,
 				"isrc":         track.ISRC,
 				"provider_id":  track.ProviderID,
 				"item_type":    track.ItemType,
 				"album_type":   track.AlbumType,
+				"composer":     track.Composer,
 			}
 		}
 		response["tracks"] = tracks
@@ -3090,10 +3170,13 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 					"images":       track.ResolvedCoverURL(),
 					"release_date": track.ReleaseDate,
 					"track_number": track.TrackNumber,
+					"total_tracks": track.TotalTracks,
 					"disc_number":  track.DiscNumber,
+					"total_discs":  track.TotalDiscs,
 					"isrc":         track.ISRC,
 					"provider_id":  track.ProviderID,
 					"spotify_id":   track.SpotifyID,
+					"composer":     track.Composer,
 				}
 			}
 			artistResponse["top_tracks"] = topTracks
@@ -3111,7 +3194,7 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 }
 
 func FindURLHandlerJSON(url string) string {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	handler := manager.FindURLHandler(url)
 	if handler == nil {
 		return ""
@@ -3120,7 +3203,7 @@ func FindURLHandlerJSON(url string) string {
 }
 
 func GetAlbumWithExtensionJSON(extensionID, albumID string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.GetExtension(extensionID)
 	if err != nil {
 		return "", err
@@ -3133,7 +3216,7 @@ func GetAlbumWithExtensionJSON(extensionID, albumID string) (string, error) {
 		return "", fmt.Errorf("extension '%s' is disabled", extensionID)
 	}
 
-	provider := NewExtensionProviderWrapper(ext)
+	provider := newExtensionProviderWrapper(ext)
 	album, err := provider.GetAlbum(albumID)
 	if err != nil {
 		return "", err
@@ -3163,11 +3246,14 @@ func GetAlbumWithExtensionJSON(extensionID, albumID string) (string, error) {
 			"cover_url":    trackCover,
 			"release_date": track.ReleaseDate,
 			"track_number": trackNum,
+			"total_tracks": track.TotalTracks,
 			"disc_number":  track.DiscNumber,
+			"total_discs":  track.TotalDiscs,
 			"isrc":         track.ISRC,
 			"provider_id":  track.ProviderID,
 			"item_type":    track.ItemType,
 			"album_type":   track.AlbumType,
+			"composer":     track.Composer,
 		}
 	}
 
@@ -3193,7 +3279,7 @@ func GetAlbumWithExtensionJSON(extensionID, albumID string) (string, error) {
 }
 
 func GetPlaylistWithExtensionJSON(extensionID, playlistID string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.GetExtension(extensionID)
 	if err != nil {
 		return "", err
@@ -3264,11 +3350,14 @@ func GetPlaylistWithExtensionJSON(extensionID, playlistID string) (string, error
 			"cover_url":    trackCover,
 			"release_date": track.ReleaseDate,
 			"track_number": track.TrackNumber,
+			"total_tracks": track.TotalTracks,
 			"disc_number":  track.DiscNumber,
+			"total_discs":  track.TotalDiscs,
 			"isrc":         track.ISRC,
 			"provider_id":  track.ProviderID,
 			"item_type":    track.ItemType,
 			"album_type":   track.AlbumType,
+			"composer":     track.Composer,
 		}
 	}
 
@@ -3291,7 +3380,7 @@ func GetPlaylistWithExtensionJSON(extensionID, playlistID string) (string, error
 }
 
 func GetArtistWithExtensionJSON(extensionID, artistID string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.GetExtension(extensionID)
 	if err != nil {
 		return "", err
@@ -3301,7 +3390,7 @@ func GetArtistWithExtensionJSON(extensionID, artistID string) (string, error) {
 		return "", fmt.Errorf("extension '%s' is not a metadata provider", extensionID)
 	}
 
-	provider := NewExtensionProviderWrapper(ext)
+	provider := newExtensionProviderWrapper(ext)
 	artist, err := provider.GetArtist(artistID)
 	if err != nil {
 		return "", err
@@ -3375,10 +3464,13 @@ func GetArtistWithExtensionJSON(extensionID, artistID string) (string, error) {
 				"images":       track.ResolvedCoverURL(),
 				"release_date": track.ReleaseDate,
 				"track_number": track.TrackNumber,
+				"total_tracks": track.TotalTracks,
 				"disc_number":  track.DiscNumber,
+				"total_discs":  track.TotalDiscs,
 				"isrc":         track.ISRC,
 				"provider_id":  track.ProviderID,
 				"spotify_id":   track.SpotifyID,
+				"composer":     track.Composer,
 			}
 		}
 		response["top_tracks"] = topTracks
@@ -3393,7 +3485,7 @@ func GetArtistWithExtensionJSON(extensionID, artistID string) (string, error) {
 }
 
 func GetURLHandlersJSON() (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	handlers := manager.GetURLHandlers()
 
 	result := make([]map[string]interface{}, 0, len(handlers))
@@ -3421,7 +3513,7 @@ func RunPostProcessingJSON(filePath, metadataJSON string) (string, error) {
 		}
 	}
 
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	result, err := manager.RunPostProcessing(filePath, metadata)
 	if err != nil {
 		return "", err
@@ -3450,7 +3542,7 @@ func RunPostProcessingV2JSON(inputJSON, metadataJSON string) (string, error) {
 		}
 	}
 
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	result, err := manager.RunPostProcessingV2(input, metadata)
 	if err != nil {
 		return "", err
@@ -3465,7 +3557,7 @@ func RunPostProcessingV2JSON(inputJSON, metadataJSON string) (string, error) {
 }
 
 func GetPostProcessingProvidersJSON() (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	providers := manager.GetPostProcessingProviders()
 
 	result := make([]map[string]interface{}, 0, len(providers))
@@ -3631,7 +3723,7 @@ func ClearStoreCacheJSON() error {
 }
 
 func callExtensionFunctionJSON(extensionID, functionName string, timeout time.Duration) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.GetExtension(extensionID)
 	if err != nil {
 		return "", err

go_backend/exports_test.go

@@ -224,3 +224,47 @@ func TestBuildReEnrichFFmpegMetadataOmitsEmptyFields(t *testing.T) {
 		}
 	}
 }
+
+func TestApplyReEnrichTrackMetadataCopiesComposerAndTotals(t *testing.T) {
+	req := reEnrichRequest{}
+
+	applyReEnrichTrackMetadata(&req, ExtTrackMetadata{
+		TrackNumber: 7,
+		TotalTracks: 12,
+		DiscNumber:  2,
+		TotalDiscs:  3,
+		Composer:    "Composer",
+	})
+
+	if req.TrackNumber != 7 || req.TotalTracks != 12 {
+		t.Fatalf("track metadata = %d/%d", req.TrackNumber, req.TotalTracks)
+	}
+	if req.DiscNumber != 2 || req.TotalDiscs != 3 {
+		t.Fatalf("disc metadata = %d/%d", req.DiscNumber, req.TotalDiscs)
+	}
+	if req.Composer != "Composer" {
+		t.Fatalf("composer = %q", req.Composer)
+	}
+}
+
+func TestBuildReEnrichFFmpegMetadataFormatsTotalsAndComposer(t *testing.T) {
+	req := reEnrichRequest{
+		TrackNumber: 7,
+		TotalTracks: 12,
+		DiscNumber:  2,
+		TotalDiscs:  3,
+		Composer:    "Composer",
+	}
+
+	metadata := buildReEnrichFFmpegMetadata(&req, "")
+
+	if metadata["TRACKNUMBER"] != "7/12" {
+		t.Fatalf("TRACKNUMBER = %q", metadata["TRACKNUMBER"])
+	}
+	if metadata["DISCNUMBER"] != "2/3" {
+		t.Fatalf("DISCNUMBER = %q", metadata["DISCNUMBER"])
+	}
+	if metadata["COMPOSER"] != "Composer" {
+		t.Fatalf("COMPOSER = %q", metadata["COMPOSER"])
+	}
+}

go_backend/extension_manager.go

@@ -43,12 +43,12 @@ func compareVersions(v1, v2 string) int {
 	return 0
 }
 
-type LoadedExtension struct {
+type loadedExtension struct {
 	ID          string             `json:"id"`
 	Manifest    *ExtensionManifest `json:"manifest"`
 	VM          *goja.Runtime      `json:"-"`
 	VMMu        sync.Mutex         `json:"-"`
-	runtime     *ExtensionRuntime
+	runtime     *extensionRuntime
 	initialized bool
 	Enabled     bool   `json:"enabled"`
 	Error       string `json:"error,omitempty"`
@@ -73,7 +73,7 @@ func getExtensionInitSettings(extensionID string) map[string]interface{} {
 	return filtered
 }
 
-func ensureRuntimeReadyLocked(ext *LoadedExtension, applyStoredSettings bool) error {
+func ensureRuntimeReadyLocked(ext *loadedExtension, applyStoredSettings bool) error {
 	if ext.VM == nil || ext.runtime == nil {
 		if err := initializeVMLocked(ext); err != nil {
 			ext.Error = err.Error()
@@ -100,14 +100,14 @@ func ensureRuntimeReadyLocked(ext *LoadedExtension, applyStoredSettings bool) er
 	return nil
 }
 
-func (ext *LoadedExtension) ensureRuntimeReady() error {
+func (ext *loadedExtension) ensureRuntimeReady() error {
 	ext.VMMu.Lock()
 	defer ext.VMMu.Unlock()
 
 	return ensureRuntimeReadyLocked(ext, true)
 }
 
-func (ext *LoadedExtension) lockReadyVM() (*goja.Runtime, error) {
+func (ext *loadedExtension) lockReadyVM() (*goja.Runtime, error) {
 	ext.VMMu.Lock()
 	if err := ensureRuntimeReadyLocked(ext, true); err != nil {
 		ext.VMMu.Unlock()
@@ -116,28 +116,28 @@ func (ext *LoadedExtension) lockReadyVM() (*goja.Runtime, error) {
 	return ext.VM, nil
 }
 
-type ExtensionManager struct {
+type extensionManager struct {
 	mu            sync.RWMutex
-	extensions    map[string]*LoadedExtension
+	extensions    map[string]*loadedExtension
 	extensionsDir string
 	dataDir       string
 }
 
 var (
-	globalExtManager     *ExtensionManager
+	globalExtManager     *extensionManager
 	globalExtManagerOnce sync.Once
 )
 
-func GetExtensionManager() *ExtensionManager {
+func getExtensionManager() *extensionManager {
 	globalExtManagerOnce.Do(func() {
-		globalExtManager = &ExtensionManager{
+		globalExtManager = &extensionManager{
-			extensions: make(map[string]*LoadedExtension),
+			extensions: make(map[string]*loadedExtension),
 		}
 	})
 	return globalExtManager
 }
 
-func (m *ExtensionManager) SetDirectories(extensionsDir, dataDir string) error {
+func (m *extensionManager) SetDirectories(extensionsDir, dataDir string) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -154,7 +154,7 @@ func (m *ExtensionManager) SetDirectories(extensionsDir, dataDir string) error {
 	return nil
 }
 
-func (m *ExtensionManager) LoadExtensionFromFile(filePath string) (*LoadedExtension, error) {
+func (m *extensionManager) LoadExtensionFromFile(filePath string) (*loadedExtension, error) {
 	if !strings.HasSuffix(strings.ToLower(filePath), ".spotiflac-ext") {
 		return nil, fmt.Errorf("Invalid file format. Please select a .spotiflac-ext file")
 	}
@@ -272,7 +272,7 @@ func (m *ExtensionManager) LoadExtensionFromFile(filePath string) (*LoadedExtens
 		return nil, fmt.Errorf("failed to create extension data directory: %w", err)
 	}
 
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID:        manifest.Name,
 		Manifest:  manifest,
 		Enabled:   false, // New extensions start disabled
@@ -292,7 +292,7 @@ func (m *ExtensionManager) LoadExtensionFromFile(filePath string) (*LoadedExtens
 	return ext, nil
 }
 
-func initializeVMLocked(ext *LoadedExtension) error {
+func initializeVMLocked(ext *loadedExtension) error {
 	ext.VM = nil
 	ext.runtime = nil
 	ext.initialized = false
@@ -305,7 +305,7 @@ func initializeVMLocked(ext *LoadedExtension) error {
 		return fmt.Errorf("failed to read index.js: %w", err)
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 	ext.runtime = runtime
 	runtime.RegisterAPIs(vm)
 	runtime.RegisterGoBackendAPIs(vm)
@@ -342,14 +342,14 @@ func initializeVMLocked(ext *LoadedExtension) error {
 	return nil
 }
 
-func (m *ExtensionManager) initializeVM(ext *LoadedExtension) error {
+func (m *extensionManager) initializeVM(ext *loadedExtension) error {
 	ext.VMMu.Lock()
 	defer ext.VMMu.Unlock()
 	return initializeVMLocked(ext)
 }
 
 func initializeExtensionWithSettingsLocked(
-	ext *LoadedExtension,
+	ext *loadedExtension,
 	settings map[string]interface{},
 ) error {
 	if ext.VM == nil {
@@ -405,7 +405,7 @@ func initializeExtensionWithSettingsLocked(
 	return nil
 }
 
-func runCleanupLocked(ext *LoadedExtension) error {
+func runCleanupLocked(ext *loadedExtension) error {
 	if ext.VM != nil {
 		script := `
 			(function() {
@@ -446,7 +446,7 @@ func runCleanupLocked(ext *LoadedExtension) error {
 	return nil
 }
 
-func teardownVMLocked(ext *LoadedExtension) {
+func teardownVMLocked(ext *loadedExtension) {
 	if err := runCleanupLocked(ext); err != nil {
 		GoLog("[Extension] Error calling cleanup for %s: %v\n", ext.ID, err)
 	}
@@ -461,7 +461,7 @@ func teardownVMLocked(ext *LoadedExtension) {
 	ext.initialized = false
 }
 
-func validateExtensionLoad(ext *LoadedExtension) error {
+func validateExtensionLoad(ext *loadedExtension) error {
 	ext.VMMu.Lock()
 	defer ext.VMMu.Unlock()
 
@@ -472,7 +472,7 @@ func validateExtensionLoad(ext *LoadedExtension) error {
 	return nil
 }
 
-func (m *ExtensionManager) UnloadExtension(extensionID string) error {
+func (m *extensionManager) UnloadExtension(extensionID string) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -491,7 +491,7 @@ func (m *ExtensionManager) UnloadExtension(extensionID string) error {
 	return nil
 }
 
-func (m *ExtensionManager) GetExtension(extensionID string) (*LoadedExtension, error) {
+func (m *extensionManager) GetExtension(extensionID string) (*loadedExtension, error) {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
@@ -502,18 +502,18 @@ func (m *ExtensionManager) GetExtension(extensionID string) (*LoadedExtension, e
 	return ext, nil
 }
 
-func (m *ExtensionManager) GetAllExtensions() []*LoadedExtension {
+func (m *extensionManager) GetAllExtensions() []*loadedExtension {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	result := make([]*LoadedExtension, 0, len(m.extensions))
+	result := make([]*loadedExtension, 0, len(m.extensions))
 	for _, ext := range m.extensions {
 		result = append(result, ext)
 	}
 	return result
 }
 
-func (m *ExtensionManager) SetExtensionEnabled(extensionID string, enabled bool) error {
+func (m *extensionManager) SetExtensionEnabled(extensionID string, enabled bool) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -547,7 +547,7 @@ func (m *ExtensionManager) SetExtensionEnabled(extensionID string, enabled bool)
 	return nil
 }
 
-func (m *ExtensionManager) LoadExtensionsFromDirectory(dirPath string) ([]string, []error) {
+func (m *extensionManager) LoadExtensionsFromDirectory(dirPath string) ([]string, []error) {
 	var loaded []string
 	var errors []error
 
@@ -585,7 +585,7 @@ func (m *ExtensionManager) LoadExtensionsFromDirectory(dirPath string) ([]string
 	return loaded, errors
 }
 
-func (m *ExtensionManager) loadExtensionFromDirectory(dirPath string) (*LoadedExtension, error) {
+func (m *extensionManager) loadExtensionFromDirectory(dirPath string) (*loadedExtension, error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -615,7 +615,7 @@ func (m *ExtensionManager) loadExtensionFromDirectory(dirPath string) (*LoadedEx
 		return nil, fmt.Errorf("failed to create extension data directory: %w", err)
 	}
 
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID:        manifest.Name,
 		Manifest:  manifest,
 		Enabled:   false, // Will be restored from settings store
@@ -643,7 +643,7 @@ func (m *ExtensionManager) loadExtensionFromDirectory(dirPath string) (*LoadedEx
 	return ext, nil
 }
 
-func (m *ExtensionManager) RemoveExtension(extensionID string) error {
+func (m *extensionManager) RemoveExtension(extensionID string) error {
 	ext, err := m.GetExtension(extensionID)
 	if err != nil {
 		return err
@@ -663,7 +663,7 @@ func (m *ExtensionManager) RemoveExtension(extensionID string) error {
 }
 
 // Only allows upgrades (new version > current version), not downgrades
-func (m *ExtensionManager) UpgradeExtension(filePath string) (*LoadedExtension, error) {
+func (m *extensionManager) UpgradeExtension(filePath string) (*loadedExtension, error) {
 	if !strings.HasSuffix(strings.ToLower(filePath), ".spotiflac-ext") {
 		return nil, fmt.Errorf("Invalid file format. Please select a .spotiflac-ext file")
 	}
@@ -777,7 +777,7 @@ func (m *ExtensionManager) UpgradeExtension(filePath string) (*LoadedExtension,
 		}
 	}
 
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID:        newManifest.Name,
 		Manifest:  newManifest,
 		Enabled:   wasEnabled, // Preserve enabled state from before upgrade
@@ -812,7 +812,7 @@ type ExtensionUpgradeInfo struct {
 	IsInstalled    bool   `json:"is_installed"`
 }
 
-func (m *ExtensionManager) checkExtensionUpgradeInternal(filePath string) (*ExtensionUpgradeInfo, error) {
+func (m *extensionManager) checkExtensionUpgradeInternal(filePath string) (*ExtensionUpgradeInfo, error) {
 	if !strings.HasSuffix(strings.ToLower(filePath), ".spotiflac-ext") {
 		return nil, fmt.Errorf("Invalid file format. Please select a .spotiflac-ext file")
 	}
@@ -871,7 +871,7 @@ func (m *ExtensionManager) checkExtensionUpgradeInternal(filePath string) (*Exte
 	return info, nil
 }
 
-func (m *ExtensionManager) CheckExtensionUpgradeJSON(filePath string) (string, error) {
+func (m *extensionManager) CheckExtensionUpgradeJSON(filePath string) (string, error) {
 	info, err := m.checkExtensionUpgradeInternal(filePath)
 	if err != nil {
 		return "", err
@@ -885,7 +885,7 @@ func (m *ExtensionManager) CheckExtensionUpgradeJSON(filePath string) (string, e
 	return string(jsonBytes), nil
 }
 
-func (m *ExtensionManager) GetInstalledExtensionsJSON() (string, error) {
+func (m *extensionManager) GetInstalledExtensionsJSON() (string, error) {
 	extensions := m.GetAllExtensions()
 
 	type ExtensionInfo struct {
@@ -982,7 +982,7 @@ func (m *ExtensionManager) GetInstalledExtensionsJSON() (string, error) {
 	return string(jsonBytes), nil
 }
 
-func (m *ExtensionManager) InitializeExtension(extensionID string, settings map[string]interface{}) error {
+func (m *extensionManager) InitializeExtension(extensionID string, settings map[string]interface{}) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -1000,7 +1000,7 @@ func (m *ExtensionManager) InitializeExtension(extensionID string, settings map[
 	return initializeExtensionWithSettingsLocked(ext, settings)
 }
 
-func (m *ExtensionManager) CleanupExtension(extensionID string) error {
+func (m *extensionManager) CleanupExtension(extensionID string) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -1022,7 +1022,7 @@ func (m *ExtensionManager) CleanupExtension(extensionID string) error {
 	return nil
 }
 
-func (m *ExtensionManager) UnloadAllExtensions() {
+func (m *extensionManager) UnloadAllExtensions() {
 	m.mu.Lock()
 	extensionIDs := make([]string, 0, len(m.extensions))
 	for id := range m.extensions {
@@ -1037,7 +1037,7 @@ func (m *ExtensionManager) UnloadAllExtensions() {
 	GoLog("[Extension] All extensions unloaded\n")
 }
 
-func (m *ExtensionManager) InvokeAction(extensionID string, actionName string) (map[string]interface{}, error) {
+func (m *extensionManager) InvokeAction(extensionID string, actionName string) (map[string]interface{}, error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 

go_backend/extension_providers.go

@@ -26,7 +26,9 @@ type ExtTrackMetadata struct {
 	Images      string `json:"images,omitempty"`
 	ReleaseDate string `json:"release_date,omitempty"`
 	TrackNumber int    `json:"track_number,omitempty"`
+	TotalTracks int    `json:"total_tracks,omitempty"`
 	DiscNumber  int    `json:"disc_number,omitempty"`
+	TotalDiscs  int    `json:"total_discs,omitempty"`
 	ISRC        string `json:"isrc,omitempty"`
 	ProviderID  string `json:"provider_id"`
 	ItemType    string `json:"item_type,omitempty"`
@@ -41,6 +43,7 @@ type ExtTrackMetadata struct {
 	Label     string `json:"label,omitempty"`
 	Copyright string `json:"copyright,omitempty"`
 	Genre     string `json:"genre,omitempty"`
+	Composer  string `json:"composer,omitempty"`
 }
 
 func (t *ExtTrackMetadata) ResolvedCoverURL() string {
@@ -113,19 +116,19 @@ type ExtDownloadResult struct {
 	DecryptionKey string `json:"decryption_key,omitempty"`
 }
 
-type ExtensionProviderWrapper struct {
+type extensionProviderWrapper struct {
-	extension *LoadedExtension
+	extension *loadedExtension
 	vm        *goja.Runtime
 }
 
-func NewExtensionProviderWrapper(ext *LoadedExtension) *ExtensionProviderWrapper {
+func newExtensionProviderWrapper(ext *loadedExtension) *extensionProviderWrapper {
-	return &ExtensionProviderWrapper{
+	return &extensionProviderWrapper{
 		extension: ext,
 		vm:        ext.VM,
 	}
 }
 
-func (p *ExtensionProviderWrapper) lockReadyVM() error {
+func (p *extensionProviderWrapper) lockReadyVM() error {
 	vm, err := p.extension.lockReadyVM()
 	if err != nil {
 		return err
@@ -134,7 +137,7 @@ func (p *ExtensionProviderWrapper) lockReadyVM() error {
 	return nil
 }
 
-func (p *ExtensionProviderWrapper) SearchTracks(query string, limit int) (*ExtSearchResult, error) {
+func (p *extensionProviderWrapper) SearchTracks(query string, limit int) (*ExtSearchResult, error) {
 	if !p.extension.Manifest.IsMetadataProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a metadata provider", p.extension.ID)
 	}
@@ -194,7 +197,7 @@ func (p *ExtensionProviderWrapper) SearchTracks(query string, limit int) (*ExtSe
 	return &searchResult, nil
 }
 
-func (p *ExtensionProviderWrapper) GetTrack(trackID string) (*ExtTrackMetadata, error) {
+func (p *extensionProviderWrapper) GetTrack(trackID string) (*ExtTrackMetadata, error) {
 	if !p.extension.Manifest.IsMetadataProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a metadata provider", p.extension.ID)
 	}
@@ -243,7 +246,7 @@ func (p *ExtensionProviderWrapper) GetTrack(trackID string) (*ExtTrackMetadata,
 	return &track, nil
 }
 
-func (p *ExtensionProviderWrapper) GetAlbum(albumID string) (*ExtAlbumMetadata, error) {
+func (p *extensionProviderWrapper) GetAlbum(albumID string) (*ExtAlbumMetadata, error) {
 	if !p.extension.Manifest.IsMetadataProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a metadata provider", p.extension.ID)
 	}
@@ -295,7 +298,7 @@ func (p *ExtensionProviderWrapper) GetAlbum(albumID string) (*ExtAlbumMetadata,
 	return &album, nil
 }
 
-func (p *ExtensionProviderWrapper) GetArtist(artistID string) (*ExtArtistMetadata, error) {
+func (p *extensionProviderWrapper) GetArtist(artistID string) (*ExtArtistMetadata, error) {
 	if !p.extension.Manifest.IsMetadataProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a metadata provider", p.extension.ID)
 	}
@@ -350,7 +353,7 @@ func (p *ExtensionProviderWrapper) GetArtist(artistID string) (*ExtArtistMetadat
 	return &artist, nil
 }
 
-func (p *ExtensionProviderWrapper) EnrichTrack(track *ExtTrackMetadata) (*ExtTrackMetadata, error) {
+func (p *extensionProviderWrapper) EnrichTrack(track *ExtTrackMetadata) (*ExtTrackMetadata, error) {
 	if !p.extension.Manifest.IsMetadataProvider() {
 		return track, nil
 	}
@@ -412,7 +415,7 @@ func (p *ExtensionProviderWrapper) EnrichTrack(track *ExtTrackMetadata) (*ExtTra
 	return &enrichedTrack, nil
 }
 
-func (p *ExtensionProviderWrapper) CheckAvailability(isrc, trackName, artistName, spotifyID, deezerID string) (*ExtAvailabilityResult, error) {
+func (p *extensionProviderWrapper) CheckAvailability(isrc, trackName, artistName, spotifyID, deezerID string) (*ExtAvailabilityResult, error) {
 	if !p.extension.Manifest.IsDownloadProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a download provider", p.extension.ID)
 	}
@@ -460,7 +463,7 @@ func (p *ExtensionProviderWrapper) CheckAvailability(isrc, trackName, artistName
 	return &availability, nil
 }
 
-func (p *ExtensionProviderWrapper) GetDownloadURL(trackID, quality string) (*ExtDownloadURLResult, error) {
+func (p *extensionProviderWrapper) GetDownloadURL(trackID, quality string) (*ExtDownloadURLResult, error) {
 	if !p.extension.Manifest.IsDownloadProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a download provider", p.extension.ID)
 	}
@@ -510,7 +513,7 @@ func (p *ExtensionProviderWrapper) GetDownloadURL(trackID, quality string) (*Ext
 
 const ExtDownloadTimeout = DownloadTimeout
 
-func (p *ExtensionProviderWrapper) Download(trackID, quality, outputPath, itemID string, onProgress func(percent int)) (*ExtDownloadResult, error) {
+func (p *extensionProviderWrapper) Download(trackID, quality, outputPath, itemID string, onProgress func(percent int)) (*ExtDownloadResult, error) {
 	if !p.extension.Manifest.IsDownloadProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a download provider", p.extension.ID)
 	}
@@ -601,40 +604,40 @@ func (p *ExtensionProviderWrapper) Download(trackID, quality, outputPath, itemID
 	return &downloadResult, nil
 }
 
-func (m *ExtensionManager) GetMetadataProviders() []*ExtensionProviderWrapper {
+func (m *extensionManager) GetMetadataProviders() []*extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	var providers []*ExtensionProviderWrapper
+	var providers []*extensionProviderWrapper
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.IsMetadataProvider() && ext.Error == "" {
-			providers = append(providers, NewExtensionProviderWrapper(ext))
+			providers = append(providers, newExtensionProviderWrapper(ext))
 		}
 	}
 	return providers
 }
 
-func (m *ExtensionManager) GetDownloadProviders() []*ExtensionProviderWrapper {
+func (m *extensionManager) GetDownloadProviders() []*extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	var providers []*ExtensionProviderWrapper
+	var providers []*extensionProviderWrapper
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.IsDownloadProvider() && ext.Error == "" {
-			providers = append(providers, NewExtensionProviderWrapper(ext))
+			providers = append(providers, newExtensionProviderWrapper(ext))
 		}
 	}
 	return providers
 }
 
-func (m *ExtensionManager) SearchTracksWithExtensions(query string, limit int) ([]ExtTrackMetadata, error) {
+func (m *extensionManager) SearchTracksWithExtensions(query string, limit int) ([]ExtTrackMetadata, error) {
 	providers := m.GetMetadataProviders()
 	if len(providers) == 0 {
 		return nil, nil
 	}
 
-	providerByID := make(map[string]*ExtensionProviderWrapper, len(providers))
+	providerByID := make(map[string]*extensionProviderWrapper, len(providers))
-	orderedProviders := make([]*ExtensionProviderWrapper, 0, len(providers))
+	orderedProviders := make([]*extensionProviderWrapper, 0, len(providers))
 	for _, provider := range providers {
 		providerByID[provider.extension.ID] = provider
 	}
@@ -775,7 +778,9 @@ func normalizeBuiltInMetadataTrack(track TrackMetadata, providerID string) ExtTr
 		Images:      track.Images,
 		ReleaseDate: track.ReleaseDate,
 		TrackNumber: track.TrackNumber,
+		TotalTracks: track.TotalTracks,
 		DiscNumber:  track.DiscNumber,
+		TotalDiscs:  track.TotalDiscs,
 		ISRC:        track.ISRC,
 		ProviderID:  providerID,
 		SpotifyID:   prefixedID,
@@ -783,6 +788,7 @@ func normalizeBuiltInMetadataTrack(track TrackMetadata, providerID string) ExtTr
 		TidalID:     tidalID,
 		QobuzID:     qobuzID,
 		AlbumType:   track.AlbumType,
+		Composer:    track.Composer,
 	}
 }
 
@@ -824,13 +830,13 @@ func searchBuiltInMetadataTracks(providerID, query string, limit int) ([]ExtTrac
 	}
 }
 
-func (m *ExtensionManager) SearchTracksWithMetadataProviders(query string, limit int, includeExtensions bool) ([]ExtTrackMetadata, error) {
+func (m *extensionManager) SearchTracksWithMetadataProviders(query string, limit int, includeExtensions bool) ([]ExtTrackMetadata, error) {
 	priority := GetMetadataProviderPriority()
 	if limit <= 0 {
 		limit = 20
 	}
 
-	extensionProviders := make(map[string]*ExtensionProviderWrapper)
+	extensionProviders := make(map[string]*extensionProviderWrapper)
 	if includeExtensions {
 		for _, provider := range m.GetMetadataProviders() {
 			extensionProviders[provider.extension.ID] = provider
@@ -910,7 +916,7 @@ func (m *ExtensionManager) SearchTracksWithMetadataProviders(query string, limit
 
 func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, error) {
 	priority := GetProviderPriority()
-	extManager := GetExtensionManager()
+	extManager := getExtensionManager()
 	strictMode := !req.UseFallback
 	selectedProvider := strings.TrimSpace(req.Service)
 
@@ -965,7 +971,7 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 		if err == nil && ext.Enabled && ext.Error == "" && ext.Manifest.IsMetadataProvider() {
 			GoLog("[DownloadWithExtensionFallback] Enriching track from extension '%s'...\n", req.Source)
 
-			provider := NewExtensionProviderWrapper(ext)
+			provider := newExtensionProviderWrapper(ext)
 			trackMeta := &ExtTrackMetadata{
 				ID:          req.SpotifyID,
 				Name:        req.TrackName,
@@ -975,8 +981,11 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 				ISRC:        req.ISRC,
 				ReleaseDate: req.ReleaseDate,
 				TrackNumber: req.TrackNumber,
+				TotalTracks: req.TotalTracks,
 				DiscNumber:  req.DiscNumber,
+				TotalDiscs:  req.TotalDiscs,
 				ProviderID:  req.Source,
+				Composer:    req.Composer,
 			}
 
 			enrichedTrack, err := provider.EnrichTrack(trackMeta)
@@ -1041,10 +1050,22 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 					GoLog("[DownloadWithExtensionFallback] TrackNumber from enrichment: %d\n", enrichedTrack.TrackNumber)
 					req.TrackNumber = enrichedTrack.TrackNumber
 				}
+				if enrichedTrack.TotalTracks > 0 && req.TotalTracks == 0 {
+					GoLog("[DownloadWithExtensionFallback] TotalTracks from enrichment: %d\n", enrichedTrack.TotalTracks)
+					req.TotalTracks = enrichedTrack.TotalTracks
+				}
 				if enrichedTrack.DiscNumber > 0 && req.DiscNumber == 0 {
 					GoLog("[DownloadWithExtensionFallback] DiscNumber from enrichment: %d\n", enrichedTrack.DiscNumber)
 					req.DiscNumber = enrichedTrack.DiscNumber
 				}
+				if enrichedTrack.TotalDiscs > 0 && req.TotalDiscs == 0 {
+					GoLog("[DownloadWithExtensionFallback] TotalDiscs from enrichment: %d\n", enrichedTrack.TotalDiscs)
+					req.TotalDiscs = enrichedTrack.TotalDiscs
+				}
+				if enrichedTrack.Composer != "" && req.Composer == "" {
+					GoLog("[DownloadWithExtensionFallback] Composer from enrichment: %s\n", enrichedTrack.Composer)
+					req.Composer = enrichedTrack.Composer
+				}
 			}
 		}
 	}
@@ -1077,9 +1098,18 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 			if track.TrackNumber > 0 && req.TrackNumber == 0 {
 				req.TrackNumber = track.TrackNumber
 			}
+			if track.TotalTracks > 0 && req.TotalTracks == 0 {
+				req.TotalTracks = track.TotalTracks
+			}
 			if track.DiscNumber > 0 && req.DiscNumber == 0 {
 				req.DiscNumber = track.DiscNumber
 			}
+			if track.TotalDiscs > 0 && req.TotalDiscs == 0 {
+				req.TotalDiscs = track.TotalDiscs
+			}
+			if track.Composer != "" && req.Composer == "" {
+				req.Composer = track.Composer
+			}
 			if track.CoverURL != "" && req.CoverURL == "" {
 				req.CoverURL = track.CoverURL
 			}
@@ -1125,7 +1155,7 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 		if err == nil && ext.Enabled && ext.Error == "" && ext.Manifest.IsDownloadProvider() {
 			skipBuiltIn = ext.Manifest.SkipBuiltInFallback
 
-			provider := NewExtensionProviderWrapper(ext)
+			provider := newExtensionProviderWrapper(ext)
 
 			trackID := req.SpotifyID
 
@@ -1346,7 +1376,7 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 				continue
 			}
 
-			provider := NewExtensionProviderWrapper(ext)
+			provider := newExtensionProviderWrapper(ext)
 
 			availability, err := provider.CheckAvailability(req.ISRC, req.TrackName, req.ArtistName, req.SpotifyID, req.DeezerID)
 			if err != nil || !availability.Available {
@@ -1594,12 +1624,15 @@ func buildOutputPath(req DownloadRequest) string {
 		"album_artist": req.AlbumArtist,
 		"track":        req.TrackNumber,
 		"track_number": req.TrackNumber,
+		"total_tracks": req.TotalTracks,
 		"disc":         req.DiscNumber,
 		"disc_number":  req.DiscNumber,
+		"total_discs":  req.TotalDiscs,
 		"year":         extractYear(req.ReleaseDate),
 		"date":         req.ReleaseDate,
 		"release_date": req.ReleaseDate,
 		"isrc":         req.ISRC,
+		"composer":     req.Composer,
 	}
 
 	filename := buildFilenameFromTemplate(req.FilenameFormat, metadata)
@@ -1624,7 +1657,7 @@ func buildOutputPath(req DownloadRequest) string {
 	return filepath.Join(outputDir, filename+ext)
 }
 
-func buildOutputPathForExtension(req DownloadRequest, ext *LoadedExtension) string {
+func buildOutputPathForExtension(req DownloadRequest, ext *loadedExtension) string {
 	if strings.TrimSpace(req.OutputPath) != "" {
 		return strings.TrimSpace(req.OutputPath)
 	}
@@ -1644,12 +1677,15 @@ func buildOutputPathForExtension(req DownloadRequest, ext *LoadedExtension) stri
 		"album_artist": req.AlbumArtist,
 		"track":        req.TrackNumber,
 		"track_number": req.TrackNumber,
+		"total_tracks": req.TotalTracks,
 		"disc":         req.DiscNumber,
 		"disc_number":  req.DiscNumber,
+		"total_discs":  req.TotalDiscs,
 		"year":         extractYear(req.ReleaseDate),
 		"date":         req.ReleaseDate,
 		"release_date": req.ReleaseDate,
 		"isrc":         req.ISRC,
+		"composer":     req.Composer,
 	}
 
 	filename := buildFilenameFromTemplate(req.FilenameFormat, metadata)
@@ -1667,7 +1703,7 @@ func buildOutputPathForExtension(req DownloadRequest, ext *LoadedExtension) stri
 	return filepath.Join(tempDir, filename+outputExt)
 }
 
-func (p *ExtensionProviderWrapper) CustomSearch(query string, options map[string]interface{}) ([]ExtTrackMetadata, error) {
+func (p *extensionProviderWrapper) CustomSearch(query string, options map[string]interface{}) ([]ExtTrackMetadata, error) {
 	if !p.extension.Manifest.HasCustomSearch() {
 		return nil, fmt.Errorf("extension '%s' does not support custom search", p.extension.ID)
 	}
@@ -1749,7 +1785,7 @@ type ExtURLHandleResult struct {
 	CoverURL string             `json:"cover_url,omitempty"`
 }
 
-func (p *ExtensionProviderWrapper) HandleURL(url string) (*ExtURLHandleResult, error) {
+func (p *extensionProviderWrapper) HandleURL(url string) (*ExtURLHandleResult, error) {
 	if !p.extension.Manifest.HasURLHandler() {
 		return nil, fmt.Errorf("extension '%s' does not support URL handling", p.extension.ID)
 	}
@@ -1835,7 +1871,7 @@ type MatchTrackResult struct {
 	Reason     string  `json:"reason,omitempty"`
 }
 
-func (p *ExtensionProviderWrapper) MatchTrack(sourceTrack map[string]interface{}, candidates []map[string]interface{}) (*MatchTrackResult, error) {
+func (p *extensionProviderWrapper) MatchTrack(sourceTrack map[string]interface{}, candidates []map[string]interface{}) (*MatchTrackResult, error) {
 	if !p.extension.Manifest.HasCustomMatching() {
 		return nil, fmt.Errorf("extension '%s' does not support custom matching", p.extension.ID)
 	}
@@ -1906,7 +1942,7 @@ type PostProcessInput struct {
 
 const PostProcessTimeout = 2 * time.Minute
 
-func (p *ExtensionProviderWrapper) PostProcess(filePath string, metadata map[string]interface{}, hookID string) (*PostProcessResult, error) {
+func (p *extensionProviderWrapper) PostProcess(filePath string, metadata map[string]interface{}, hookID string) (*PostProcessResult, error) {
 	if !p.extension.Manifest.HasPostProcessing() {
 		return nil, fmt.Errorf("extension '%s' does not support post-processing", p.extension.ID)
 	}
@@ -1969,7 +2005,7 @@ func (p *ExtensionProviderWrapper) PostProcess(filePath string, metadata map[str
 	return &postResult, nil
 }
 
-func (p *ExtensionProviderWrapper) PostProcessV2(input PostProcessInput, metadata map[string]interface{}, hookID string) (*PostProcessResult, error) {
+func (p *extensionProviderWrapper) PostProcessV2(input PostProcessInput, metadata map[string]interface{}, hookID string) (*PostProcessResult, error) {
 	if !p.extension.Manifest.HasPostProcessing() {
 		return nil, fmt.Errorf("extension '%s' does not support post-processing", p.extension.ID)
 	}
@@ -2039,39 +2075,39 @@ func (p *ExtensionProviderWrapper) PostProcessV2(input PostProcessInput, metadat
 	return &postResult, nil
 }
 
-func (m *ExtensionManager) GetSearchProviders() []*ExtensionProviderWrapper {
+func (m *extensionManager) GetSearchProviders() []*extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	var providers []*ExtensionProviderWrapper
+	var providers []*extensionProviderWrapper
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.HasCustomSearch() && ext.Error == "" {
-			providers = append(providers, NewExtensionProviderWrapper(ext))
+			providers = append(providers, newExtensionProviderWrapper(ext))
 		}
 	}
 	return providers
 }
 
-func (m *ExtensionManager) GetURLHandlers() []*ExtensionProviderWrapper {
+func (m *extensionManager) GetURLHandlers() []*extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	var providers []*ExtensionProviderWrapper
+	var providers []*extensionProviderWrapper
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.HasURLHandler() && ext.Error == "" {
-			providers = append(providers, NewExtensionProviderWrapper(ext))
+			providers = append(providers, newExtensionProviderWrapper(ext))
 		}
 	}
 	return providers
 }
 
-func (m *ExtensionManager) FindURLHandler(url string) *ExtensionProviderWrapper {
+func (m *extensionManager) FindURLHandler(url string) *extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.MatchesURL(url) && ext.Error == "" {
-			return NewExtensionProviderWrapper(ext)
+			return newExtensionProviderWrapper(ext)
 		}
 	}
 	return nil
@@ -2082,7 +2118,7 @@ type ExtURLHandleResultWithExtID struct {
 	ExtensionID string
 }
 
-func (m *ExtensionManager) HandleURLWithExtension(url string) (*ExtURLHandleResultWithExtID, error) {
+func (m *extensionManager) HandleURLWithExtension(url string) (*ExtURLHandleResultWithExtID, error) {
 	handler := m.FindURLHandler(url)
 	if handler == nil {
 		return nil, fmt.Errorf("no extension found to handle URL: %s", url)
@@ -2102,20 +2138,20 @@ func (m *ExtensionManager) HandleURLWithExtension(url string) (*ExtURLHandleResu
 	}, nil
 }
 
-func (m *ExtensionManager) GetPostProcessingProviders() []*ExtensionProviderWrapper {
+func (m *extensionManager) GetPostProcessingProviders() []*extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	var providers []*ExtensionProviderWrapper
+	var providers []*extensionProviderWrapper
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.HasPostProcessing() && ext.Error == "" {
-			providers = append(providers, NewExtensionProviderWrapper(ext))
+			providers = append(providers, newExtensionProviderWrapper(ext))
 		}
 	}
 	return providers
 }
 
-func (m *ExtensionManager) RunPostProcessing(filePath string, metadata map[string]interface{}) (*PostProcessResult, error) {
+func (m *extensionManager) RunPostProcessing(filePath string, metadata map[string]interface{}) (*PostProcessResult, error) {
 	providers := m.GetPostProcessingProviders()
 	if len(providers) == 0 {
 		return &PostProcessResult{Success: true, NewFilePath: filePath}, nil
@@ -2160,7 +2196,7 @@ func (m *ExtensionManager) RunPostProcessing(filePath string, metadata map[strin
 	return &PostProcessResult{Success: true, NewFilePath: currentPath}, nil
 }
 
-func (m *ExtensionManager) RunPostProcessingV2(input PostProcessInput, metadata map[string]interface{}) (*PostProcessResult, error) {
+func (m *extensionManager) RunPostProcessingV2(input PostProcessInput, metadata map[string]interface{}) (*PostProcessResult, error) {
 	providers := m.GetPostProcessingProviders()
 	if len(providers) == 0 {
 		return &PostProcessResult{Success: true, NewFilePath: input.Path, NewFileURI: input.URI}, nil
@@ -2228,7 +2264,7 @@ type ExtLyricsLine struct {
 	EndTimeMs   int64  `json:"endTimeMs"`
 }
 
-func (p *ExtensionProviderWrapper) FetchLyrics(trackName, artistName, albumName string, durationSec float64) (*LyricsResponse, error) {
+func (p *extensionProviderWrapper) FetchLyrics(trackName, artistName, albumName string, durationSec float64) (*LyricsResponse, error) {
 	if !p.extension.Manifest.IsLyricsProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a lyrics provider", p.extension.ID)
 	}
@@ -2326,14 +2362,14 @@ func (p *ExtensionProviderWrapper) FetchLyrics(trackName, artistName, albumName
 	return response, nil
 }
 
-func (m *ExtensionManager) GetLyricsProviders() []*ExtensionProviderWrapper {
+func (m *extensionManager) GetLyricsProviders() []*extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	var providers []*ExtensionProviderWrapper
+	var providers []*extensionProviderWrapper
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.IsLyricsProvider() && ext.Error == "" {
-			providers = append(providers, NewExtensionProviderWrapper(ext))
+			providers = append(providers, newExtensionProviderWrapper(ext))
 		}
 	}
 

go_backend/extension_providers_test.go

@@ -51,7 +51,7 @@ func TestSearchTracksWithMetadataProvidersUsesPriorityAndDedupes(t *testing.T) {
 		}
 	}
 
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	tracks, err := manager.SearchTracksWithMetadataProviders("query", 3, false)
 	if err != nil {
 		t.Fatalf("SearchTracksWithMetadataProviders returned error: %v", err)

go_backend/extension_runtime.go

@@ -80,7 +80,7 @@ func SetExtensionTokens(extensionID string, accessToken, refreshToken string, ex
 	state.IsAuthenticated = accessToken != ""
 }
 
-type ExtensionRuntime struct {
+type extensionRuntime struct {
 	extensionID    string
 	manifest       *ExtensionManifest
 	settings       map[string]interface{}
@@ -123,10 +123,10 @@ var (
 	privateIPCacheMu sync.RWMutex
 )
 
-func NewExtensionRuntime(ext *LoadedExtension) *ExtensionRuntime {
+func newExtensionRuntime(ext *loadedExtension) *extensionRuntime {
 	jar, _ := newSimpleCookieJar()
 
-	runtime := &ExtensionRuntime{
+	runtime := &extensionRuntime{
 		extensionID:       ext.ID,
 		manifest:          ext.Manifest,
 		settings:          make(map[string]interface{}),
@@ -142,25 +142,25 @@ func NewExtensionRuntime(ext *LoadedExtension) *ExtensionRuntime {
 	return runtime
 }
 
-func (r *ExtensionRuntime) setActiveDownloadItemID(itemID string) {
+func (r *extensionRuntime) setActiveDownloadItemID(itemID string) {
 	r.activeDownloadMu.Lock()
 	defer r.activeDownloadMu.Unlock()
 	r.activeDownloadItemID = strings.TrimSpace(itemID)
 }
 
-func (r *ExtensionRuntime) clearActiveDownloadItemID() {
+func (r *extensionRuntime) clearActiveDownloadItemID() {
 	r.activeDownloadMu.Lock()
 	defer r.activeDownloadMu.Unlock()
 	r.activeDownloadItemID = ""
 }
 
-func (r *ExtensionRuntime) getActiveDownloadItemID() string {
+func (r *extensionRuntime) getActiveDownloadItemID() string {
 	r.activeDownloadMu.RLock()
 	defer r.activeDownloadMu.RUnlock()
 	return r.activeDownloadItemID
 }
 
-func newExtensionHTTPClient(ext *LoadedExtension, jar http.CookieJar, timeout time.Duration) *http.Client {
+func newExtensionHTTPClient(ext *loadedExtension, jar http.CookieJar, timeout time.Duration) *http.Client {
 	// Extension sandbox enforces HTTPS-only domains. Do not apply global
 	// allow_http scheme downgrade here, because some extension APIs (e.g.
 	// spotify-web) will redirect http -> https and can end up in 301 loops.
@@ -329,11 +329,11 @@ func (j *simpleCookieJar) Cookies(u *url.URL) []*http.Cookie {
 	return j.cookies[u.Host]
 }
 
-func (r *ExtensionRuntime) SetSettings(settings map[string]interface{}) {
+func (r *extensionRuntime) SetSettings(settings map[string]interface{}) {
 	r.settings = settings
 }
 
-func (r *ExtensionRuntime) RegisterAPIs(vm *goja.Runtime) {
+func (r *extensionRuntime) RegisterAPIs(vm *goja.Runtime) {
 	r.vm = vm
 
 	httpObj := vm.NewObject()

go_backend/extension_runtime_auth.go

@@ -52,7 +52,7 @@ func summarizeURLForLog(urlStr string) string {
 	return fmt.Sprintf("%s://%s%s", parsed.Scheme, parsed.Host, parsed.Path)
 }
 
-func (r *ExtensionRuntime) authOpenUrl(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authOpenUrl(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -99,7 +99,7 @@ func (r *ExtensionRuntime) authOpenUrl(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) authGetCode(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authGetCode(call goja.FunctionCall) goja.Value {
 	extensionAuthStateMu.RLock()
 	defer extensionAuthStateMu.RUnlock()
 
@@ -111,7 +111,7 @@ func (r *ExtensionRuntime) authGetCode(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(state.AuthCode)
 }
 
-func (r *ExtensionRuntime) authSetCode(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authSetCode(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(false)
 	}
@@ -149,7 +149,7 @@ func (r *ExtensionRuntime) authSetCode(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(true)
 }
 
-func (r *ExtensionRuntime) authClear(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authClear(call goja.FunctionCall) goja.Value {
 	extensionAuthStateMu.Lock()
 	delete(extensionAuthState, r.extensionID)
 	extensionAuthStateMu.Unlock()
@@ -162,7 +162,7 @@ func (r *ExtensionRuntime) authClear(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(true)
 }
 
-func (r *ExtensionRuntime) authIsAuthenticated(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authIsAuthenticated(call goja.FunctionCall) goja.Value {
 	extensionAuthStateMu.RLock()
 	defer extensionAuthStateMu.RUnlock()
 
@@ -178,7 +178,7 @@ func (r *ExtensionRuntime) authIsAuthenticated(call goja.FunctionCall) goja.Valu
 	return r.vm.ToValue(state.IsAuthenticated)
 }
 
-func (r *ExtensionRuntime) authGetTokens(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authGetTokens(call goja.FunctionCall) goja.Value {
 	extensionAuthStateMu.RLock()
 	defer extensionAuthStateMu.RUnlock()
 
@@ -228,7 +228,7 @@ func generatePKCEChallenge(verifier string) string {
 	return base64.RawURLEncoding.EncodeToString(hash[:])
 }
 
-func (r *ExtensionRuntime) authGeneratePKCE(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authGeneratePKCE(call goja.FunctionCall) goja.Value {
 	length := 64
 	if len(call.Arguments) > 0 && !goja.IsUndefined(call.Arguments[0]) {
 		if l, ok := call.Arguments[0].Export().(float64); ok && l >= 43 && l <= 128 {
@@ -265,7 +265,7 @@ func (r *ExtensionRuntime) authGeneratePKCE(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) authGetPKCE(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authGetPKCE(call goja.FunctionCall) goja.Value {
 	extensionAuthStateMu.RLock()
 	defer extensionAuthStateMu.RUnlock()
 
@@ -281,7 +281,7 @@ func (r *ExtensionRuntime) authGetPKCE(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) authStartOAuthWithPKCE(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authStartOAuthWithPKCE(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -385,7 +385,7 @@ func (r *ExtensionRuntime) authStartOAuthWithPKCE(call goja.FunctionCall) goja.V
 	})
 }
 
-func (r *ExtensionRuntime) authExchangeCodeWithPKCE(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authExchangeCodeWithPKCE(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,

go_backend/extension_runtime_ffmpeg.go

@@ -50,7 +50,7 @@ func ClearFFmpegCommand(commandID string) {
 	delete(ffmpegCommands, commandID)
 }
 
-func (r *ExtensionRuntime) ffmpegExecute(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) ffmpegExecute(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -107,7 +107,7 @@ func (r *ExtensionRuntime) ffmpegExecute(call goja.FunctionCall) goja.Value {
 	}
 }
 
-func (r *ExtensionRuntime) ffmpegGetInfo(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) ffmpegGetInfo(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -134,7 +134,7 @@ func (r *ExtensionRuntime) ffmpegGetInfo(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) ffmpegConvert(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) ffmpegConvert(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,

go_backend/extension_runtime_file.go

@@ -71,7 +71,7 @@ func isPathWithinBase(baseDir, targetPath string) bool {
 	return true
 }
 
-func (r *ExtensionRuntime) validatePath(path string) (string, error) {
+func (r *extensionRuntime) validatePath(path string) (string, error) {
 	if !r.manifest.Permissions.File {
 		return "", fmt.Errorf("file access denied: extension does not have 'file' permission")
 	}
@@ -106,7 +106,7 @@ func (r *ExtensionRuntime) validatePath(path string) (string, error) {
 	return absPath, nil
 }
 
-func (r *ExtensionRuntime) fileDownload(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileDownload(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -271,7 +271,7 @@ func (r *ExtensionRuntime) fileDownload(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) fileExists(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileExists(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(false)
 	}
@@ -286,7 +286,7 @@ func (r *ExtensionRuntime) fileExists(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(err == nil)
 }
 
-func (r *ExtensionRuntime) fileDelete(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileDelete(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -315,7 +315,7 @@ func (r *ExtensionRuntime) fileDelete(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) fileRead(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileRead(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -346,7 +346,7 @@ func (r *ExtensionRuntime) fileRead(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) fileWrite(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileWrite(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -386,7 +386,7 @@ func (r *ExtensionRuntime) fileWrite(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) fileCopy(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileCopy(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -459,7 +459,7 @@ func (r *ExtensionRuntime) fileCopy(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) fileMove(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileMove(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -507,7 +507,7 @@ func (r *ExtensionRuntime) fileMove(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) fileGetSize(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileGetSize(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,

go_backend/extension_runtime_http.go

@@ -17,7 +17,7 @@ type HTTPResponse struct {
 	Headers    map[string]string `json:"headers"`
 }
 
-func (r *ExtensionRuntime) validateDomain(urlStr string) error {
+func (r *extensionRuntime) validateDomain(urlStr string) error {
 	parsed, err := url.Parse(urlStr)
 	if err != nil {
 		return fmt.Errorf("invalid URL: %w", err)
@@ -49,7 +49,7 @@ func (r *ExtensionRuntime) validateDomain(urlStr string) error {
 	return nil
 }
 
-func (r *ExtensionRuntime) httpGet(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpGet(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"error": "URL is required",
@@ -124,7 +124,7 @@ func (r *ExtensionRuntime) httpGet(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) httpPost(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpPost(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"error": "URL is required",
@@ -221,7 +221,7 @@ func (r *ExtensionRuntime) httpPost(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) httpRequest(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpRequest(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"error": "URL is required",
@@ -330,19 +330,19 @@ func (r *ExtensionRuntime) httpRequest(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) httpPut(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpPut(call goja.FunctionCall) goja.Value {
 	return r.httpMethodShortcut("PUT", call)
 }
 
-func (r *ExtensionRuntime) httpDelete(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpDelete(call goja.FunctionCall) goja.Value {
 	return r.httpMethodShortcut("DELETE", call)
 }
 
-func (r *ExtensionRuntime) httpPatch(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpPatch(call goja.FunctionCall) goja.Value {
 	return r.httpMethodShortcut("PATCH", call)
 }
 
-func (r *ExtensionRuntime) httpMethodShortcut(method string, call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpMethodShortcut(method string, call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"error": "URL is required",
@@ -455,7 +455,7 @@ func (r *ExtensionRuntime) httpMethodShortcut(method string, call goja.FunctionC
 	})
 }
 
-func (r *ExtensionRuntime) httpClearCookies(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpClearCookies(call goja.FunctionCall) goja.Value {
 	if jar, ok := r.cookieJar.(*simpleCookieJar); ok {
 		jar.mu.Lock()
 		jar.cookies = make(map[string][]*http.Cookie)

go_backend/extension_runtime_matching.go

@@ -6,7 +6,7 @@ import (
 	"github.com/dop251/goja"
 )
 
-func (r *ExtensionRuntime) matchingCompareStrings(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) matchingCompareStrings(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(0.0)
 	}
@@ -22,7 +22,7 @@ func (r *ExtensionRuntime) matchingCompareStrings(call goja.FunctionCall) goja.V
 	return r.vm.ToValue(similarity)
 }
 
-func (r *ExtensionRuntime) matchingCompareDuration(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) matchingCompareDuration(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(false)
 	}
@@ -43,7 +43,7 @@ func (r *ExtensionRuntime) matchingCompareDuration(call goja.FunctionCall) goja.
 	return r.vm.ToValue(diff <= tolerance)
 }
 
-func (r *ExtensionRuntime) matchingNormalizeString(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) matchingNormalizeString(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}

go_backend/extension_runtime_polyfills.go

@@ -12,7 +12,7 @@ import (
 	"github.com/dop251/goja"
 )
 
-func (r *ExtensionRuntime) fetchPolyfill(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fetchPolyfill(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.createFetchError("URL is required")
 	}
@@ -133,7 +133,7 @@ func (r *ExtensionRuntime) fetchPolyfill(call goja.FunctionCall) goja.Value {
 	return responseObj
 }
 
-func (r *ExtensionRuntime) createFetchError(message string) goja.Value {
+func (r *extensionRuntime) createFetchError(message string) goja.Value {
 	errorObj := r.vm.NewObject()
 	errorObj.Set("ok", false)
 	errorObj.Set("status", 0)
@@ -148,7 +148,7 @@ func (r *ExtensionRuntime) createFetchError(message string) goja.Value {
 	return errorObj
 }
 
-func (r *ExtensionRuntime) atobPolyfill(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) atobPolyfill(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -164,7 +164,7 @@ func (r *ExtensionRuntime) atobPolyfill(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(string(decoded))
 }
 
-func (r *ExtensionRuntime) btoaPolyfill(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) btoaPolyfill(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -172,7 +172,7 @@ func (r *ExtensionRuntime) btoaPolyfill(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(base64.StdEncoding.EncodeToString([]byte(input)))
 }
 
-func (r *ExtensionRuntime) registerTextEncoderDecoder(vm *goja.Runtime) {
+func (r *extensionRuntime) registerTextEncoderDecoder(vm *goja.Runtime) {
 	vm.Set("TextEncoder", func(call goja.ConstructorCall) *goja.Object {
 		encoder := call.This
 		encoder.Set("encoding", "utf-8")
@@ -252,7 +252,7 @@ func (r *ExtensionRuntime) registerTextEncoderDecoder(vm *goja.Runtime) {
 	})
 }
 
-func (r *ExtensionRuntime) registerURLClass(vm *goja.Runtime) {
+func (r *extensionRuntime) registerURLClass(vm *goja.Runtime) {
 	vm.Set("URL", func(call goja.ConstructorCall) *goja.Object {
 		urlObj := call.This
 
@@ -416,7 +416,7 @@ func (r *ExtensionRuntime) registerURLClass(vm *goja.Runtime) {
 	})
 }
 
-func (r *ExtensionRuntime) registerJSONGlobal(vm *goja.Runtime) {
+func (r *extensionRuntime) registerJSONGlobal(vm *goja.Runtime) {
 	jsonScript := `
 		if (typeof JSON === 'undefined') {
 			var JSON = {

go_backend/extension_runtime_storage.go

@@ -21,7 +21,7 @@ const (
 	storageFlushRetryDelay   = 2 * time.Second
 )
 
-func (r *ExtensionRuntime) getStoragePath() string {
+func (r *extensionRuntime) getStoragePath() string {
 	return filepath.Join(r.dataDir, "storage.json")
 }
 
@@ -36,7 +36,7 @@ func cloneInterfaceMap(src map[string]interface{}) map[string]interface{} {
 	return dst
 }
 
-func (r *ExtensionRuntime) ensureStorageLoaded() error {
+func (r *extensionRuntime) ensureStorageLoaded() error {
 	r.storageMu.RLock()
 	if r.storageLoaded {
 		r.storageMu.RUnlock()
@@ -74,7 +74,7 @@ func (r *ExtensionRuntime) ensureStorageLoaded() error {
 	return nil
 }
 
-func (r *ExtensionRuntime) loadStorage() (map[string]interface{}, error) {
+func (r *extensionRuntime) loadStorage() (map[string]interface{}, error) {
 	if err := r.ensureStorageLoaded(); err != nil {
 		return nil, err
 	}
@@ -84,7 +84,7 @@ func (r *ExtensionRuntime) loadStorage() (map[string]interface{}, error) {
 	return cloneInterfaceMap(r.storageCache), nil
 }
 
-func (r *ExtensionRuntime) queueStorageFlushLocked(delay time.Duration) {
+func (r *extensionRuntime) queueStorageFlushLocked(delay time.Duration) {
 	if r.storageClosed {
 		return
 	}
@@ -94,7 +94,7 @@ func (r *ExtensionRuntime) queueStorageFlushLocked(delay time.Duration) {
 	r.storageTimer = time.AfterFunc(delay, r.flushStorageDirtyAsync)
 }
 
-func (r *ExtensionRuntime) persistStorageSnapshot(storage map[string]interface{}) error {
+func (r *extensionRuntime) persistStorageSnapshot(storage map[string]interface{}) error {
 	data, err := json.Marshal(storage)
 	if err != nil {
 		return err
@@ -106,13 +106,13 @@ func (r *ExtensionRuntime) persistStorageSnapshot(storage map[string]interface{}
 	return os.WriteFile(r.getStoragePath(), data, 0600)
 }
 
-func (r *ExtensionRuntime) flushStorageDirtyAsync() {
+func (r *extensionRuntime) flushStorageDirtyAsync() {
 	if err := r.flushStorageDirty(); err != nil {
 		GoLog("[Extension:%s] Storage flush error: %v\n", r.extensionID, err)
 	}
 }
 
-func (r *ExtensionRuntime) flushStorageDirty() error {
+func (r *extensionRuntime) flushStorageDirty() error {
 	r.storageMu.Lock()
 	if r.storageClosed {
 		r.storageTimer = nil
@@ -140,7 +140,7 @@ func (r *ExtensionRuntime) flushStorageDirty() error {
 	return nil
 }
 
-func (r *ExtensionRuntime) flushStorageNow() error {
+func (r *extensionRuntime) flushStorageNow() error {
 	r.storageMu.Lock()
 	if r.storageTimer != nil {
 		r.storageTimer.Stop()
@@ -157,7 +157,7 @@ func (r *ExtensionRuntime) flushStorageNow() error {
 	return r.persistStorageSnapshot(snapshot)
 }
 
-func (r *ExtensionRuntime) closeStorageFlusher() {
+func (r *extensionRuntime) closeStorageFlusher() {
 	r.storageMu.Lock()
 	r.storageClosed = true
 	r.storageDirty = false
@@ -168,7 +168,7 @@ func (r *ExtensionRuntime) closeStorageFlusher() {
 	r.storageMu.Unlock()
 }
 
-func (r *ExtensionRuntime) storageGet(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) storageGet(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return goja.Undefined()
 	}
@@ -193,7 +193,7 @@ func (r *ExtensionRuntime) storageGet(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(value)
 }
 
-func (r *ExtensionRuntime) storageSet(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) storageSet(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(false)
 	}
@@ -225,7 +225,7 @@ func (r *ExtensionRuntime) storageSet(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(true)
 }
 
-func (r *ExtensionRuntime) storageRemove(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) storageRemove(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(false)
 	}
@@ -254,15 +254,15 @@ func (r *ExtensionRuntime) storageRemove(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(true)
 }
 
-func (r *ExtensionRuntime) getCredentialsPath() string {
+func (r *extensionRuntime) getCredentialsPath() string {
 	return filepath.Join(r.dataDir, ".credentials.enc")
 }
 
-func (r *ExtensionRuntime) getSaltPath() string {
+func (r *extensionRuntime) getSaltPath() string {
 	return filepath.Join(r.dataDir, ".cred_salt")
 }
 
-func (r *ExtensionRuntime) getOrCreateSalt() ([]byte, error) {
+func (r *extensionRuntime) getOrCreateSalt() ([]byte, error) {
 	saltPath := r.getSaltPath()
 
 	salt, err := os.ReadFile(saltPath)
@@ -282,7 +282,7 @@ func (r *ExtensionRuntime) getOrCreateSalt() ([]byte, error) {
 	return salt, nil
 }
 
-func (r *ExtensionRuntime) getEncryptionKey() ([]byte, error) {
+func (r *extensionRuntime) getEncryptionKey() ([]byte, error) {
 	salt, err := r.getOrCreateSalt()
 	if err != nil {
 		return nil, err
@@ -293,7 +293,7 @@ func (r *ExtensionRuntime) getEncryptionKey() ([]byte, error) {
 	return hash[:], nil
 }
 
-func (r *ExtensionRuntime) ensureCredentialsLoaded() error {
+func (r *extensionRuntime) ensureCredentialsLoaded() error {
 	r.credentialsMu.RLock()
 	if r.credentialsLoaded {
 		r.credentialsMu.RUnlock()
@@ -340,7 +340,7 @@ func (r *ExtensionRuntime) ensureCredentialsLoaded() error {
 	return nil
 }
 
-func (r *ExtensionRuntime) loadCredentials() (map[string]interface{}, error) {
+func (r *extensionRuntime) loadCredentials() (map[string]interface{}, error) {
 	if err := r.ensureCredentialsLoaded(); err != nil {
 		return nil, err
 	}
@@ -350,7 +350,7 @@ func (r *ExtensionRuntime) loadCredentials() (map[string]interface{}, error) {
 	return cloneInterfaceMap(r.credentialsCache), nil
 }
 
-func (r *ExtensionRuntime) saveCredentials(creds map[string]interface{}) error {
+func (r *extensionRuntime) saveCredentials(creds map[string]interface{}) error {
 	data, err := json.Marshal(creds)
 	if err != nil {
 		return err
@@ -377,7 +377,7 @@ func (r *ExtensionRuntime) saveCredentials(creds map[string]interface{}) error {
 	return nil
 }
 
-func (r *ExtensionRuntime) credentialsStore(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) credentialsStore(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -414,7 +414,7 @@ func (r *ExtensionRuntime) credentialsStore(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) credentialsGet(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) credentialsGet(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return goja.Undefined()
 	}
@@ -439,7 +439,7 @@ func (r *ExtensionRuntime) credentialsGet(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(value)
 }
 
-func (r *ExtensionRuntime) credentialsRemove(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) credentialsRemove(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(false)
 	}
@@ -464,7 +464,7 @@ func (r *ExtensionRuntime) credentialsRemove(call goja.FunctionCall) goja.Value
 	return r.vm.ToValue(true)
 }
 
-func (r *ExtensionRuntime) credentialsHas(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) credentialsHas(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(false)
 	}

go_backend/extension_runtime_storage_test.go

@@ -11,7 +11,7 @@ import (
 	"github.com/dop251/goja"
 )
 
-func setStorageValue(t *testing.T, runtime *ExtensionRuntime, key string, value interface{}) {
+func setStorageValue(t *testing.T, runtime *extensionRuntime, key string, value interface{}) {
 	t.Helper()
 	result := runtime.storageSet(goja.FunctionCall{
 		Arguments: []goja.Value{
@@ -39,7 +39,7 @@ func readStorageMap(t *testing.T, storagePath string) map[string]interface{} {
 }
 
 func TestExtensionRuntimeStorage_DebouncedWriteCompactJSON(t *testing.T) {
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID: "storage-test",
 		Manifest: &ExtensionManifest{
 			Name: "storage-test",
@@ -47,7 +47,7 @@ func TestExtensionRuntimeStorage_DebouncedWriteCompactJSON(t *testing.T) {
 		DataDir: t.TempDir(),
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 	runtime.storageFlushDelay = 25 * time.Millisecond
 	runtime.RegisterAPIs(goja.New())
 
@@ -86,7 +86,7 @@ func TestExtensionRuntimeStorage_DebouncedWriteCompactJSON(t *testing.T) {
 }
 
 func TestUnloadExtension_FlushesPendingStorage(t *testing.T) {
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID: "unload-storage-test",
 		Manifest: &ExtensionManifest{
 			Name: "unload-storage-test",
@@ -95,13 +95,13 @@ func TestUnloadExtension_FlushesPendingStorage(t *testing.T) {
 		VM:      goja.New(),
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 	runtime.storageFlushDelay = time.Hour
 	runtime.RegisterAPIs(ext.VM)
 	ext.runtime = runtime
 
-	manager := &ExtensionManager{
+	manager := &extensionManager{
-		extensions: map[string]*LoadedExtension{
+		extensions: map[string]*loadedExtension{
 			ext.ID: ext,
 		},
 	}

go_backend/extension_runtime_utils.go

@@ -16,7 +16,7 @@ import (
 	"github.com/dop251/goja"
 )
 
-func (r *ExtensionRuntime) base64Encode(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) base64Encode(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -24,7 +24,7 @@ func (r *ExtensionRuntime) base64Encode(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(base64.StdEncoding.EncodeToString([]byte(input)))
 }
 
-func (r *ExtensionRuntime) base64Decode(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) base64Decode(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -36,7 +36,7 @@ func (r *ExtensionRuntime) base64Decode(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(string(decoded))
 }
 
-func (r *ExtensionRuntime) md5Hash(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) md5Hash(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -45,7 +45,7 @@ func (r *ExtensionRuntime) md5Hash(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(hex.EncodeToString(hash[:]))
 }
 
-func (r *ExtensionRuntime) sha256Hash(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) sha256Hash(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -54,7 +54,7 @@ func (r *ExtensionRuntime) sha256Hash(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(hex.EncodeToString(hash[:]))
 }
 
-func (r *ExtensionRuntime) hmacSHA256(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) hmacSHA256(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue("")
 	}
@@ -66,7 +66,7 @@ func (r *ExtensionRuntime) hmacSHA256(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(hex.EncodeToString(mac.Sum(nil)))
 }
 
-func (r *ExtensionRuntime) hmacSHA256Base64(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) hmacSHA256Base64(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue("")
 	}
@@ -78,7 +78,7 @@ func (r *ExtensionRuntime) hmacSHA256Base64(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(base64.StdEncoding.EncodeToString(mac.Sum(nil)))
 }
 
-func (r *ExtensionRuntime) hmacSHA1(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) hmacSHA1(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue([]byte{})
 	}
@@ -130,7 +130,7 @@ func (r *ExtensionRuntime) hmacSHA1(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(jsArray)
 }
 
-func (r *ExtensionRuntime) parseJSON(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) parseJSON(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return goja.Undefined()
 	}
@@ -145,7 +145,7 @@ func (r *ExtensionRuntime) parseJSON(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(result)
 }
 
-func (r *ExtensionRuntime) stringifyJSON(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) stringifyJSON(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -160,7 +160,7 @@ func (r *ExtensionRuntime) stringifyJSON(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(string(data))
 }
 
-func (r *ExtensionRuntime) cryptoEncrypt(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) cryptoEncrypt(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -187,7 +187,7 @@ func (r *ExtensionRuntime) cryptoEncrypt(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) cryptoDecrypt(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) cryptoDecrypt(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -222,7 +222,7 @@ func (r *ExtensionRuntime) cryptoDecrypt(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) cryptoGenerateKey(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) cryptoGenerateKey(call goja.FunctionCall) goja.Value {
 	length := 32
 	if len(call.Arguments) > 0 && !goja.IsUndefined(call.Arguments[0]) {
 		if l, ok := call.Arguments[0].Export().(float64); ok {
@@ -245,35 +245,35 @@ func (r *ExtensionRuntime) cryptoGenerateKey(call goja.FunctionCall) goja.Value
 	})
 }
 
-func (r *ExtensionRuntime) randomUserAgent(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) randomUserAgent(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(getRandomUserAgent())
 }
 
-func (r *ExtensionRuntime) logDebug(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) logDebug(call goja.FunctionCall) goja.Value {
 	msg := r.formatLogArgs(call.Arguments)
 	GoLog("[Extension:%s:DEBUG] %s\n", r.extensionID, msg)
 	return goja.Undefined()
 }
 
-func (r *ExtensionRuntime) logInfo(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) logInfo(call goja.FunctionCall) goja.Value {
 	msg := r.formatLogArgs(call.Arguments)
 	GoLog("[Extension:%s:INFO] %s\n", r.extensionID, msg)
 	return goja.Undefined()
 }
 
-func (r *ExtensionRuntime) logWarn(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) logWarn(call goja.FunctionCall) goja.Value {
 	msg := r.formatLogArgs(call.Arguments)
 	GoLog("[Extension:%s:WARN] %s\n", r.extensionID, msg)
 	return goja.Undefined()
 }
 
-func (r *ExtensionRuntime) logError(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) logError(call goja.FunctionCall) goja.Value {
 	msg := r.formatLogArgs(call.Arguments)
 	GoLog("[Extension:%s:ERROR] %s\n", r.extensionID, msg)
 	return goja.Undefined()
 }
 
-func (r *ExtensionRuntime) formatLogArgs(args []goja.Value) string {
+func (r *extensionRuntime) formatLogArgs(args []goja.Value) string {
 	parts := make([]string, len(args))
 	for i, arg := range args {
 		parts[i] = fmt.Sprintf("%v", arg.Export())
@@ -281,7 +281,7 @@ func (r *ExtensionRuntime) formatLogArgs(args []goja.Value) string {
 	return strings.Join(parts, " ")
 }
 
-func (r *ExtensionRuntime) sanitizeFilenameWrapper(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) sanitizeFilenameWrapper(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -289,7 +289,7 @@ func (r *ExtensionRuntime) sanitizeFilenameWrapper(call goja.FunctionCall) goja.
 	return r.vm.ToValue(sanitizeFilename(input))
 }
 
-func (r *ExtensionRuntime) RegisterGoBackendAPIs(vm *goja.Runtime) {
+func (r *extensionRuntime) RegisterGoBackendAPIs(vm *goja.Runtime) {
 	gobackendObj := vm.Get("gobackend")
 	if gobackendObj == nil || goja.IsUndefined(gobackendObj) {
 		gobackendObj = vm.NewObject()

go_backend/extension_store.go

@@ -295,7 +295,7 @@ func (s *extensionStore) getExtensionsWithStatus(forceRefresh bool) ([]storeExte
 		return nil, err
 	}
 
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	installed := make(map[string]string) // id -> version
 
 	if manager != nil {

go_backend/extension_test.go

@@ -99,7 +99,7 @@ func TestIsDomainAllowed(t *testing.T) {
 
 func TestExtensionRuntime_NetworkSandbox(t *testing.T) {
 	// Create a mock extension with limited network permissions
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID: "test-ext",
 		Manifest: &ExtensionManifest{
 			Name: "test-ext",
@@ -110,7 +110,7 @@ func TestExtensionRuntime_NetworkSandbox(t *testing.T) {
 		DataDir: t.TempDir(),
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 
 	if err := runtime.validateDomain("https://api.allowed.com/path"); err != nil {
 		t.Errorf("Expected api.allowed.com to be allowed, got error: %v", err)
@@ -132,7 +132,7 @@ func TestExtensionRuntime_NetworkSandbox(t *testing.T) {
 func TestExtensionRuntime_FileSandbox(t *testing.T) {
 	tempDir := t.TempDir()
 
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID: "test-ext",
 		Manifest: &ExtensionManifest{
 			Name: "test-ext",
@@ -143,7 +143,7 @@ func TestExtensionRuntime_FileSandbox(t *testing.T) {
 		DataDir: tempDir,
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 
 	validPath, err := runtime.validatePath("test.txt")
 	if err != nil {
@@ -177,7 +177,7 @@ func TestExtensionRuntime_FileSandbox(t *testing.T) {
 		t.Error("Expected absolute path to be blocked")
 	}
 
-	extNoFile := &LoadedExtension{
+	extNoFile := &loadedExtension{
 		ID: "test-ext-no-file",
 		Manifest: &ExtensionManifest{
 			Name: "test-ext-no-file",
@@ -187,7 +187,7 @@ func TestExtensionRuntime_FileSandbox(t *testing.T) {
 		},
 		DataDir: tempDir,
 	}
-	runtimeNoFile := NewExtensionRuntime(extNoFile)
+	runtimeNoFile := newExtensionRuntime(extNoFile)
 	_, err = runtimeNoFile.validatePath("test.txt")
 	if err == nil {
 		t.Error("Expected file access to be denied without file permission")
@@ -195,7 +195,7 @@ func TestExtensionRuntime_FileSandbox(t *testing.T) {
 }
 
 func TestExtensionRuntime_UtilityFunctions(t *testing.T) {
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID: "test-ext",
 		Manifest: &ExtensionManifest{
 			Name: "test-ext",
@@ -203,7 +203,7 @@ func TestExtensionRuntime_UtilityFunctions(t *testing.T) {
 		DataDir: t.TempDir(),
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 	vm := goja.New()
 	runtime.RegisterAPIs(vm)
 
@@ -243,7 +243,7 @@ func TestExtensionRuntime_UtilityFunctions(t *testing.T) {
 
 func TestExtensionRuntime_SSRFProtection(t *testing.T) {
 	// Create extension with limited network permissions
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID: "test-ext",
 		Manifest: &ExtensionManifest{
 			Name: "test-ext",
@@ -254,7 +254,7 @@ func TestExtensionRuntime_SSRFProtection(t *testing.T) {
 		DataDir: t.TempDir(),
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 
 	privateIPs := []string{
 		"http://localhost/admin",

go_backend/extension_timeout.go

@@ -53,7 +53,7 @@ func RunWithTimeout(vm *goja.Runtime, script string, timeout time.Duration) (goj
 						IsTimeout: true,
 					}}
 				} else {
-					GoLog("[ExtensionRuntime] panic during JS execution: %v\n%s\n", r, string(debug.Stack()))
+					GoLog("[extensionRuntime] panic during JS execution: %v\n%s\n", r, string(debug.Stack()))
 					resultCh <- result{nil, fmt.Errorf("panic during execution: %v", r)}
 				}
 			}
@@ -90,7 +90,7 @@ func RunWithTimeout(vm *goja.Runtime, script string, timeout time.Duration) (goj
 		case <-time.After(60 * time.Second):
 			// Goroutine is truly stuck (e.g. HTTP read with no timeout).
 			// Log a warning — the VM should NOT be reused after this.
-			GoLog("[ExtensionRuntime] WARNING: JS goroutine did not exit within 60s after interrupt, VM may be unsafe\n")
+			GoLog("[extensionRuntime] WARNING: JS goroutine did not exit within 60s after interrupt, VM may be unsafe\n")
 			return nil, &JSExecutionError{
 				Message:   "execution timeout exceeded (force)",
 				IsTimeout: true,

go_backend/library_scan.go

@@ -24,13 +24,18 @@ type LibraryScanResult struct {
 	FileModTime          int64  `json:"fileModTime,omitempty"` // Unix timestamp in milliseconds
 	ISRC                 string `json:"isrc,omitempty"`
 	TrackNumber          int    `json:"trackNumber,omitempty"`
+	TotalTracks          int    `json:"totalTracks,omitempty"`
 	DiscNumber           int    `json:"discNumber,omitempty"`
+	TotalDiscs           int    `json:"totalDiscs,omitempty"`
 	Duration             int    `json:"duration,omitempty"`
 	ReleaseDate          string `json:"releaseDate,omitempty"`
 	BitDepth             int    `json:"bitDepth,omitempty"`
 	SampleRate           int    `json:"sampleRate,omitempty"`
 	Bitrate              int    `json:"bitrate,omitempty"` // kbps, for lossy formats (MP3, Opus, Vorbis)
 	Genre                string `json:"genre,omitempty"`
+	Composer             string `json:"composer,omitempty"`
+	Label                string `json:"label,omitempty"`
+	Copyright            string `json:"copyright,omitempty"`
 	Format               string `json:"format,omitempty"`
 	MetadataFromFilename bool   `json:"metadataFromFilename,omitempty"`
 }
@@ -365,9 +370,14 @@ func scanFLACFile(filePath string, result *LibraryScanResult, displayNameHint st
 	result.AlbumArtist = metadata.AlbumArtist
 	result.ISRC = metadata.ISRC
 	result.TrackNumber = metadata.TrackNumber
+	result.TotalTracks = metadata.TotalTracks
 	result.DiscNumber = metadata.DiscNumber
+	result.TotalDiscs = metadata.TotalDiscs
 	result.ReleaseDate = metadata.Date
 	result.Genre = metadata.Genre
+	result.Composer = metadata.Composer
+	result.Label = metadata.Label
+	result.Copyright = metadata.Copyright
 
 	quality, err := GetAudioQuality(filePath)
 	if err == nil {
@@ -397,12 +407,17 @@ func scanM4AFile(filePath string, result *LibraryScanResult, displayNameHint str
 		result.AlbumArtist = metadata.AlbumArtist
 		result.ISRC = metadata.ISRC
 		result.TrackNumber = metadata.TrackNumber
+		result.TotalTracks = metadata.TotalTracks
 		result.DiscNumber = metadata.DiscNumber
+		result.TotalDiscs = metadata.TotalDiscs
 		result.ReleaseDate = metadata.Date
 		if result.ReleaseDate == "" {
 			result.ReleaseDate = metadata.Year
 		}
 		result.Genre = metadata.Genre
+		result.Composer = metadata.Composer
+		result.Label = metadata.Label
+		result.Copyright = metadata.Copyright
 	}
 
 	quality, err := GetM4AQuality(filePath)
@@ -427,7 +442,9 @@ func scanMP3File(filePath string, result *LibraryScanResult, displayNameHint str
 	result.AlbumName = metadata.Album
 	result.AlbumArtist = metadata.AlbumArtist
 	result.TrackNumber = metadata.TrackNumber
+	result.TotalTracks = metadata.TotalTracks
 	result.DiscNumber = metadata.DiscNumber
+	result.TotalDiscs = metadata.TotalDiscs
 	result.Genre = metadata.Genre
 	if metadata.Date != "" {
 		result.ReleaseDate = metadata.Date
@@ -435,6 +452,9 @@ func scanMP3File(filePath string, result *LibraryScanResult, displayNameHint str
 		result.ReleaseDate = metadata.Year
 	}
 	result.ISRC = metadata.ISRC
+	result.Composer = metadata.Composer
+	result.Label = metadata.Label
+	result.Copyright = metadata.Copyright
 
 	quality, err := GetMP3Quality(filePath)
 	if err == nil {
@@ -464,9 +484,14 @@ func scanOggFile(filePath string, result *LibraryScanResult, displayNameHint str
 	result.AlbumArtist = metadata.AlbumArtist
 	result.ISRC = metadata.ISRC
 	result.TrackNumber = metadata.TrackNumber
+	result.TotalTracks = metadata.TotalTracks
 	result.DiscNumber = metadata.DiscNumber
+	result.TotalDiscs = metadata.TotalDiscs
 	result.Genre = metadata.Genre
 	result.ReleaseDate = metadata.Date
+	result.Composer = metadata.Composer
+	result.Label = metadata.Label
+	result.Copyright = metadata.Copyright
 
 	quality, err := GetOggQuality(filePath)
 	if err == nil {
@@ -501,13 +526,18 @@ func scanAPEFile(filePath string, result *LibraryScanResult, displayNameHint str
 	result.AlbumArtist = metadata.AlbumArtist
 	result.ISRC = metadata.ISRC
 	result.TrackNumber = metadata.TrackNumber
+	result.TotalTracks = metadata.TotalTracks
 	result.DiscNumber = metadata.DiscNumber
+	result.TotalDiscs = metadata.TotalDiscs
 	result.Genre = metadata.Genre
 	if metadata.Date != "" {
 		result.ReleaseDate = metadata.Date
 	} else {
 		result.ReleaseDate = metadata.Year
 	}
+	result.Composer = metadata.Composer
+	result.Label = metadata.Label
+	result.Copyright = metadata.Copyright
 
 	applyDefaultLibraryMetadata(filePath, displayNameHint, result)
 

go_backend/lyrics.go

@@ -385,8 +385,8 @@ func (c *LyricsClient) FetchLyricsAllSources(spotifyID, trackName, artistName st
 	primaryArtist := normalizeArtistName(artistName)
 	fetchOptions := GetLyricsFetchOptions()
 
-	extManager := GetExtensionManager()
+	extManager := getExtensionManager()
-	var extensionProviders []*ExtensionProviderWrapper
+	var extensionProviders []*extensionProviderWrapper
 	if extManager != nil {
 		extensionProviders = extManager.GetLyricsProviders()
 	}

go_backend/metadata.go

@@ -110,6 +110,7 @@ type Metadata struct {
 	TrackNumber   int
 	TotalTracks   int
 	DiscNumber    int
+	TotalDiscs    int
 	ISRC          string
 	Description   string
 	Lyrics        string
@@ -273,23 +274,23 @@ func ReadMetadata(filePath string) (*Metadata, error) {
 
 			trackNum := getComment(cmt, "TRACKNUMBER")
 			if trackNum != "" {
-				fmt.Sscanf(trackNum, "%d", &metadata.TrackNumber)
+				metadata.TrackNumber, metadata.TotalTracks = parseIndexPair(trackNum)
 			}
 			if metadata.TrackNumber == 0 {
 				trackNum = getComment(cmt, "TRACK")
 				if trackNum != "" {
-					fmt.Sscanf(trackNum, "%d", &metadata.TrackNumber)
+					metadata.TrackNumber, metadata.TotalTracks = parseIndexPair(trackNum)
 				}
 			}
 
 			discNum := getComment(cmt, "DISCNUMBER")
 			if discNum != "" {
-				fmt.Sscanf(discNum, "%d", &metadata.DiscNumber)
+				metadata.DiscNumber, metadata.TotalDiscs = parseIndexPair(discNum)
 			}
 			if metadata.DiscNumber == 0 {
 				discNum = getComment(cmt, "DISC")
 				if discNum != "" {
-					fmt.Sscanf(discNum, "%d", &metadata.DiscNumber)
+					metadata.DiscNumber, metadata.TotalDiscs = parseIndexPair(discNum)
 				}
 			}
 
@@ -403,26 +404,39 @@ func EditFlacFields(filePath string, fields map[string]string) error {
 		removeCommentKey(cmt, "ALBUM_ARTIST")
 	}
 
-	// Track/disc numbers: present + empty → clear; present + "0" → clear.
+	// Track/disc numbers: present + empty → clear; when only totals are edited,
-	if v, ok := fields["track_number"]; ok {
+	// preserve the current index number and rewrite the combined value.
-		trackNum := 0
+	if _, ok := fields["track_number"]; ok || fields["track_total"] != "" || hasMapKey(fields, "track_total") {
-		if v != "" {
+		currentTrackNum, currentTotalTracks := parseIndexPair(getComment(cmt, "TRACKNUMBER"))
-			fmt.Sscanf(v, "%d", &trackNum)
+		if currentTrackNum == 0 && currentTotalTracks == 0 {
+			currentTrackNum, currentTotalTracks = parseIndexPair(getComment(cmt, "TRACK"))
 		}
-		if trackNum > 0 {
+		if v, ok := fields["track_number"]; ok {
-			setOrClearComment(cmt, "TRACKNUMBER", strconv.Itoa(trackNum))
+			currentTrackNum = parsePositiveInt(v)
+		}
+		if v, ok := fields["track_total"]; ok {
+			currentTotalTracks = parsePositiveInt(v)
+		}
+		if currentTrackNum > 0 {
+			setOrClearComment(cmt, "TRACKNUMBER", formatIndexValue(currentTrackNum, currentTotalTracks))
 		} else {
 			removeCommentKey(cmt, "TRACKNUMBER")
 		}
 		removeCommentKey(cmt, "TRACK") // alias
 	}
-	if v, ok := fields["disc_number"]; ok {
+	if _, ok := fields["disc_number"]; ok || fields["disc_total"] != "" || hasMapKey(fields, "disc_total") {
-		discNum := 0
+		currentDiscNum, currentTotalDiscs := parseIndexPair(getComment(cmt, "DISCNUMBER"))
-		if v != "" {
+		if currentDiscNum == 0 && currentTotalDiscs == 0 {
-			fmt.Sscanf(v, "%d", &discNum)
+			currentDiscNum, currentTotalDiscs = parseIndexPair(getComment(cmt, "DISC"))
 		}
-		if discNum > 0 {
+		if v, ok := fields["disc_number"]; ok {
-			setOrClearComment(cmt, "DISCNUMBER", strconv.Itoa(discNum))
+			currentDiscNum = parsePositiveInt(v)
+		}
+		if v, ok := fields["disc_total"]; ok {
+			currentTotalDiscs = parsePositiveInt(v)
+		}
+		if currentDiscNum > 0 {
+			setOrClearComment(cmt, "DISCNUMBER", formatIndexValue(currentDiscNum, currentTotalDiscs))
 		} else {
 			removeCommentKey(cmt, "DISCNUMBER")
 		}
@@ -478,15 +492,11 @@ func writeVorbisMetadata(cmt *flacvorbis.MetaDataBlockVorbisComment, metadata Me
 	setComment(cmt, "DATE", metadata.Date)
 
 	if metadata.TrackNumber > 0 {
-		if metadata.TotalTracks > 0 {
+		setComment(cmt, "TRACKNUMBER", formatIndexValue(metadata.TrackNumber, metadata.TotalTracks))
-			setComment(cmt, "TRACKNUMBER", fmt.Sprintf("%d/%d", metadata.TrackNumber, metadata.TotalTracks))
-		} else {
-			setComment(cmt, "TRACKNUMBER", strconv.Itoa(metadata.TrackNumber))
-		}
 	}
 
 	if metadata.DiscNumber > 0 {
-		setComment(cmt, "DISCNUMBER", strconv.Itoa(metadata.DiscNumber))
+		setComment(cmt, "DISCNUMBER", formatIndexValue(metadata.DiscNumber, metadata.TotalDiscs))
 	}
 
 	if metadata.ISRC != "" {
@@ -953,9 +963,9 @@ func ReadM4ATags(filePath string) (*AudioMetadata, error) {
 		case "\xa9lyr":
 			metadata.Lyrics, _ = readM4ATextValue(f, header, fi.Size())
 		case "trkn":
-			metadata.TrackNumber, _ = readM4AIndexValue(f, header, fi.Size())
+			metadata.TrackNumber, metadata.TotalTracks, _ = readM4AIndexPair(f, header, fi.Size())
 		case "disk":
-			metadata.DiscNumber, _ = readM4AIndexValue(f, header, fi.Size())
+			metadata.DiscNumber, metadata.TotalDiscs, _ = readM4AIndexPair(f, header, fi.Size())
 		case "----":
 			name, value, freeformErr := readM4AFreeformValue(f, header, fi.Size())
 			if freeformErr == nil {
@@ -1150,6 +1160,41 @@ func readM4AIndexValue(f *os.File, parent atomHeader, fileSize int64) (int, erro
 	return int(binary.BigEndian.Uint16(payload[2:4])), nil
 }
 
+func readM4AIndexPair(f *os.File, parent atomHeader, fileSize int64) (int, int, error) {
+	payload, err := readM4ADataPayload(f, parent, fileSize)
+	if err != nil {
+		return 0, 0, err
+	}
+	if len(payload) < 6 {
+		return 0, 0, fmt.Errorf("index payload too short in %s", parent.typ)
+	}
+	return int(binary.BigEndian.Uint16(payload[2:4])), int(binary.BigEndian.Uint16(payload[4:6])), nil
+}
+
+func parsePositiveInt(value string) int {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return 0
+	}
+	n, _ := strconv.Atoi(value)
+	return n
+}
+
+func formatIndexValue(number, total int) string {
+	if number <= 0 {
+		return ""
+	}
+	if total > 0 {
+		return fmt.Sprintf("%d/%d", number, total)
+	}
+	return strconv.Itoa(number)
+}
+
+func hasMapKey(fields map[string]string, key string) bool {
+	_, ok := fields[key]
+	return ok
+}
+
 func readM4AFreeformValue(f *os.File, parent atomHeader, fileSize int64) (string, string, error) {
 	start := parent.offset + parent.headerSize
 	end := parent.offset + parent.size

go_backend/metadata_types.go

@@ -23,11 +23,13 @@ type TrackMetadata struct {
 	TrackNumber int    `json:"track_number"`
 	TotalTracks int    `json:"total_tracks,omitempty"`
 	DiscNumber  int    `json:"disc_number,omitempty"`
+	TotalDiscs  int    `json:"total_discs,omitempty"`
 	ExternalURL string `json:"external_urls"`
 	ISRC        string `json:"isrc"`
 	AlbumID     string `json:"album_id,omitempty"`
 	ArtistID    string `json:"artist_id,omitempty"`
 	AlbumType   string `json:"album_type,omitempty"`
+	Composer    string `json:"composer,omitempty"`
 }
 
 type AlbumTrackMetadata struct {
@@ -42,11 +44,13 @@ type AlbumTrackMetadata struct {
 	TrackNumber int    `json:"track_number"`
 	TotalTracks int    `json:"total_tracks,omitempty"`
 	DiscNumber  int    `json:"disc_number,omitempty"`
+	TotalDiscs  int    `json:"total_discs,omitempty"`
 	ExternalURL string `json:"external_urls"`
 	ISRC        string `json:"isrc"`
 	AlbumID     string `json:"album_id,omitempty"`
 	AlbumURL    string `json:"album_url,omitempty"`
 	AlbumType   string `json:"album_type,omitempty"`
+	Composer    string `json:"composer,omitempty"`
 }
 
 type AlbumInfoMetadata struct {

go_backend/qobuz.go

@@ -1030,6 +1030,7 @@ func (q *QobuzDownloader) GetAlbumMetadata(resourceID string) (*AlbumResponsePay
 	}
 
 	tracks := make([]AlbumTrackMetadata, 0, len(album.Tracks.Items))
+	totalDiscs := 0
 	for i := range album.Tracks.Items {
 		track := &album.Tracks.Items[i]
 		track.Album.ID = album.ID
@@ -1041,8 +1042,14 @@ func (q *QobuzDownloader) GetAlbumMetadata(resourceID string) (*AlbumResponsePay
 			Large:     album.Image.Large,
 		}
 		track.Album.TracksCount = album.TracksCount
+		if track.MediaNumber > totalDiscs {
+			totalDiscs = track.MediaNumber
+		}
 		tracks = append(tracks, qobuzTrackToAlbumTrackMetadata(track))
 	}
+	for i := range tracks {
+		tracks[i].TotalDiscs = totalDiscs
+	}
 
 	return &AlbumResponsePayload{
 		AlbumInfo: qobuzAlbumToAlbumInfo(album),
@@ -2793,10 +2800,12 @@ func downloadFromQobuz(req DownloadRequest) (QobuzDownloadResult, error) {
 		TrackNumber:   actualTrackNumber,
 		TotalTracks:   req.TotalTracks,
 		DiscNumber:    req.DiscNumber,
+		TotalDiscs:    req.TotalDiscs,
 		ISRC:          track.ISRC,
 		Genre:         req.Genre,
 		Label:         req.Label,
 		Copyright:     req.Copyright,
+		Composer:      req.Composer,
 	}
 
 	var coverData []byte

go_backend/tidal.go

@@ -1012,6 +1012,7 @@ func (t *TidalDownloader) GetAlbumMetadata(resourceID string) (*AlbumResponsePay
 	}
 
 	tracks := make([]AlbumTrackMetadata, 0, len(itemsModule.PagedList.Items))
+	totalDiscs := 0
 	for _, item := range itemsModule.PagedList.Items {
 		track := item.Item
 		track.Album.ID = headerModule.Album.ID
@@ -1019,8 +1020,14 @@ func (t *TidalDownloader) GetAlbumMetadata(resourceID string) (*AlbumResponsePay
 		track.Album.Cover = headerModule.Album.Cover
 		track.Album.ReleaseDate = headerModule.Album.ReleaseDate
 		track.Album.URL = headerModule.Album.URL
+		if track.VolumeNumber > totalDiscs {
+			totalDiscs = track.VolumeNumber
+		}
 		tracks = append(tracks, tidalTrackToAlbumTrackMetadata(&track))
 	}
+	for i := range tracks {
+		tracks[i].TotalDiscs = totalDiscs
+	}
 
 	return &AlbumResponsePayload{
 		AlbumInfo: tidalAlbumToAlbumInfo(&headerModule.Album),
@@ -2360,10 +2367,12 @@ func downloadFromTidal(req DownloadRequest) (TidalDownloadResult, error) {
 		TrackNumber:   actualTrackNumber,
 		TotalTracks:   req.TotalTracks,
 		DiscNumber:    actualDiscNumber,
+		TotalDiscs:    req.TotalDiscs,
 		ISRC:          track.ISRC,
 		Genre:         req.Genre,
 		Label:         req.Label,
 		Copyright:     req.Copyright,
+		Composer:      req.Composer,
 	}
 
 	var coverData []byte

lib/constants/app_info.dart

@@ -3,8 +3,8 @@ import 'package:flutter/foundation.dart';
 /// App version and info constants
 /// Update version here only - all other files will reference this
 class AppInfo {
-  static const String version = '4.2.0';
+  static const String version = '4.2.1';
-  static const String buildNumber = '121';
+  static const String buildNumber = '122';
   static const String fullVersion = '$version+$buildNumber';
 
   /// Shows "Internal" in debug builds, actual version in release.

lib/models/track.dart

@@ -16,12 +16,14 @@ class Track {
   final int duration;
   final int? trackNumber;
   final int? discNumber;
+  final int? totalDiscs;
   final String? releaseDate;
   final String? deezerId;
   final ServiceAvailability? availability;
   final String? source;
   final String? albumType;
   final int? totalTracks;
+  final String? composer;
   final String? itemType;
 
   const Track({
@@ -37,12 +39,14 @@ class Track {
     required this.duration,
     this.trackNumber,
     this.discNumber,
+    this.totalDiscs,
     this.releaseDate,
     this.deezerId,
     this.availability,
     this.source,
     this.albumType,
     this.totalTracks,
+    this.composer,
     this.itemType,
   });
 

lib/models/track.g.dart

@@ -19,6 +19,7 @@ Track _$TrackFromJson(Map<String, dynamic> json) => Track(
   duration: (json['duration'] as num).toInt(),
   trackNumber: (json['trackNumber'] as num?)?.toInt(),
   discNumber: (json['discNumber'] as num?)?.toInt(),
+  totalDiscs: (json['totalDiscs'] as num?)?.toInt(),
   releaseDate: json['releaseDate'] as String?,
   deezerId: json['deezerId'] as String?,
   availability: json['availability'] == null
@@ -29,6 +30,7 @@ Track _$TrackFromJson(Map<String, dynamic> json) => Track(
   source: json['source'] as String?,
   albumType: json['albumType'] as String?,
   totalTracks: (json['totalTracks'] as num?)?.toInt(),
+  composer: json['composer'] as String?,
   itemType: json['itemType'] as String?,
 );
 
@@ -45,12 +47,14 @@ Map<String, dynamic> _$TrackToJson(Track instance) => <String, dynamic>{
   'duration': instance.duration,
   'trackNumber': instance.trackNumber,
   'discNumber': instance.discNumber,
+  'totalDiscs': instance.totalDiscs,
   'releaseDate': instance.releaseDate,
   'deezerId': instance.deezerId,
   'availability': instance.availability,
   'source': instance.source,
   'albumType': instance.albumType,
   'totalTracks': instance.totalTracks,
+  'composer': instance.composer,
   'itemType': instance.itemType,
 };
 

lib/providers/download_queue_provider.dart

@@ -3251,11 +3251,13 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
       isrc: backendIsrc ?? baseTrack.isrc,
       trackNumber: backendTrackNum ?? baseTrack.trackNumber,
       discNumber: backendDiscNum ?? baseTrack.discNumber,
+      totalDiscs: baseTrack.totalDiscs,
       releaseDate: backendYear ?? baseTrack.releaseDate,
       deezerId: baseTrack.deezerId,
       availability: baseTrack.availability,
       albumType: baseTrack.albumType,
       totalTracks: baseTrack.totalTracks,
+      composer: baseTrack.composer,
       source: baseTrack.source,
     );
   }
@@ -3329,17 +3331,25 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
         'ARTIST': track.artistName,
         'ALBUM': track.albumName,
       };
+      String formatIndexTag(int number, int? total) {
+        if (total != null && total > 0) {
+          return '$number/$total';
+        }
+        return number.toString();
+      }
 
       final albumArtist = _resolveAlbumArtistForMetadata(track, settings);
       metadata['ALBUMARTIST'] = albumArtist;
 
       if (track.trackNumber != null && track.trackNumber! > 0) {
-        metadata['TRACKNUMBER'] = track.trackNumber.toString();
+        final trackTag = formatIndexTag(track.trackNumber!, track.totalTracks);
-        if (isFlac || isMp3) metadata['TRACK'] = track.trackNumber.toString();
+        metadata['TRACKNUMBER'] = trackTag;
+        if (isFlac || isMp3) metadata['TRACK'] = trackTag;
       }
       if (track.discNumber != null && track.discNumber! > 0) {
-        metadata['DISCNUMBER'] = track.discNumber.toString();
+        final discTag = formatIndexTag(track.discNumber!, track.totalDiscs);
-        if (isFlac || isMp3) metadata['DISC'] = track.discNumber.toString();
+        metadata['DISCNUMBER'] = discTag;
+        if (isFlac || isMp3) metadata['DISC'] = discTag;
       }
       if (track.releaseDate != null) {
         metadata['DATE'] = track.releaseDate!;
@@ -3353,6 +3363,9 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
       if (copyright != null && copyright.isNotEmpty) {
         metadata['COPYRIGHT'] = copyright;
       }
+      if (track.composer != null && track.composer!.isNotEmpty) {
+        metadata['COMPOSER'] = track.composer!;
+      }
 
       // ── Lyrics ──────────────────────────────────────────────────────
       final lyricsMode = settings.lyricsMode;
@@ -3875,7 +3888,11 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
           (trackToDownload.isrc == null ||
               trackToDownload.isrc!.isEmpty ||
               trackToDownload.trackNumber == null ||
-              trackToDownload.trackNumber == 0);
+              trackToDownload.trackNumber == 0 ||
+              trackToDownload.totalTracks == null ||
+              trackToDownload.totalTracks == 0 ||
+              (trackToDownload.composer == null ||
+                  trackToDownload.composer!.isEmpty));
 
       if (needsEnrichment) {
         try {
@@ -3901,6 +3918,13 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
               _log.d('Track data keys: ${data.keys.toList()}');
               _log.d('ISRC from API: ${data['isrc']}');
               _log.d('album_type from API: ${data['album_type']}');
+              final enrichedTotalTracks = _parsePositiveInt(
+                data['total_tracks'],
+              );
+              final enrichedTotalDiscs = _parsePositiveInt(data['total_discs']);
+              final enrichedComposer = normalizeOptionalString(
+                data['composer']?.toString(),
+              );
               trackToDownload = Track(
                 id: (data['spotify_id'] as String?) ?? trackToDownload.id,
                 name: (data['name'] as String?) ?? trackToDownload.name,
@@ -3923,14 +3947,15 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
                 isrc: (data['isrc'] as String?) ?? trackToDownload.isrc,
                 trackNumber: data['track_number'] as int?,
                 discNumber: data['disc_number'] as int?,
+                totalDiscs: enrichedTotalDiscs ?? trackToDownload.totalDiscs,
                 releaseDate: data['release_date'] as String?,
                 deezerId: rawId,
                 availability: trackToDownload.availability,
                 albumType:
                     (data['album_type'] as String?) ??
                     trackToDownload.albumType,
-                totalTracks:
+                totalTracks: enrichedTotalTracks ?? trackToDownload.totalTracks,
-                    data['total_tracks'] as int? ?? trackToDownload.totalTracks,
+                composer: enrichedComposer ?? trackToDownload.composer,
                 source: trackToDownload.source,
               );
               _log.d(
@@ -4101,7 +4126,12 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
                 trackData['release_date'] as String?,
               );
               final provTrackNum = trackData['track_number'] as int?;
+              final provTotalTracks = trackData['total_tracks'] as int?;
               final provDiscNum = trackData['disc_number'] as int?;
+              final provTotalDiscs = trackData['total_discs'] as int?;
+              final provComposer = normalizeOptionalString(
+                trackData['composer'] as String?,
+              );
 
               trackToDownload = Track(
                 id: trackToDownload.id,
@@ -4124,11 +4154,21 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
                         trackToDownload.discNumber! > 0)
                     ? trackToDownload.discNumber
                     : provDiscNum,
+                totalDiscs:
+                    (trackToDownload.totalDiscs != null &&
+                        trackToDownload.totalDiscs! > 0)
+                    ? trackToDownload.totalDiscs
+                    : provTotalDiscs,
                 releaseDate: trackToDownload.releaseDate ?? provReleaseDate,
                 deezerId: trackToDownload.deezerId,
                 availability: trackToDownload.availability,
                 albumType: trackToDownload.albumType,
-                totalTracks: trackToDownload.totalTracks,
+                totalTracks:
+                    (trackToDownload.totalTracks != null &&
+                        trackToDownload.totalTracks! > 0)
+                    ? trackToDownload.totalTracks
+                    : provTotalTracks,
+                composer: trackToDownload.composer ?? provComposer,
                 source: trackToDownload.source,
               );
 
@@ -4198,7 +4238,12 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
               trackData['isrc'] as String?,
             );
             final deezerTrackNum = trackData['track_number'] as int?;
+            final deezerTotalTracks = trackData['total_tracks'] as int?;
             final deezerDiscNum = trackData['disc_number'] as int?;
+            final deezerTotalDiscs = trackData['total_discs'] as int?;
+            final deezerComposer = normalizeOptionalString(
+              trackData['composer'] as String?,
+            );
 
             final needsEnrich =
                 (trackToDownload.releaseDate == null &&
@@ -4210,10 +4255,21 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
                         trackToDownload.trackNumber! <= 0) &&
                     deezerTrackNum != null &&
                     deezerTrackNum > 0) ||
+                ((trackToDownload.totalTracks == null ||
+                        trackToDownload.totalTracks! <= 0) &&
+                    deezerTotalTracks != null &&
+                    deezerTotalTracks > 0) ||
                 ((trackToDownload.discNumber == null ||
                         trackToDownload.discNumber! <= 0) &&
                     deezerDiscNum != null &&
-                    deezerDiscNum > 0);
+                    deezerDiscNum > 0) ||
+                ((trackToDownload.totalDiscs == null ||
+                        trackToDownload.totalDiscs! <= 0) &&
+                    deezerTotalDiscs != null &&
+                    deezerTotalDiscs > 0) ||
+                ((trackToDownload.composer == null ||
+                        trackToDownload.composer!.isEmpty) &&
+                    deezerComposer != null);
 
             if (needsEnrich) {
               trackToDownload = Track(
@@ -4239,11 +4295,21 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
                         trackToDownload.discNumber! > 0)
                     ? trackToDownload.discNumber
                     : deezerDiscNum,
+                totalDiscs:
+                    (trackToDownload.totalDiscs != null &&
+                        trackToDownload.totalDiscs! > 0)
+                    ? trackToDownload.totalDiscs
+                    : deezerTotalDiscs,
                 releaseDate: trackToDownload.releaseDate ?? deezerReleaseDate,
                 deezerId: deezerTrackId,
                 availability: trackToDownload.availability,
                 albumType: trackToDownload.albumType,
-                totalTracks: trackToDownload.totalTracks,
+                totalTracks:
+                    (trackToDownload.totalTracks != null &&
+                        trackToDownload.totalTracks! > 0)
+                    ? trackToDownload.totalTracks
+                    : deezerTotalTracks,
+                composer: trackToDownload.composer ?? deezerComposer,
                 source: trackToDownload.source,
               );
               _log.d(
@@ -4390,6 +4456,8 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
               metadataEmbeddingEnabled && settings.maxQualityCover,
           trackNumber: normalizedTrackNumber,
           discNumber: normalizedDiscNumber,
+          totalTracks: trackToDownload.totalTracks ?? 0,
+          totalDiscs: trackToDownload.totalDiscs ?? 0,
           releaseDate: trackToDownload.releaseDate ?? '',
           itemId: item.id,
           durationMs: trackToDownload.duration,
@@ -4397,6 +4465,7 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
           genre: genre ?? '',
           label: label ?? '',
           copyright: copyright ?? '',
+          composer: trackToDownload.composer ?? '',
           qobuzId: payloadQobuzId,
           tidalId: payloadTidalId,
           deezerId: deezerTrackId ?? '',

lib/providers/track_provider.dart

@@ -906,9 +906,11 @@ class TrackNotifier extends Notifier<TrackState> {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date'] as String?,
       albumType: data['album_type'] as String?,
       totalTracks: data['total_tracks'] as int?,
+      composer: data['composer']?.toString(),
     );
   }
 
@@ -939,10 +941,12 @@ class TrackNotifier extends Notifier<TrackState> {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
       totalTracks: data['total_tracks'] as int?,
       source: effectiveSource,
       albumType: data['album_type']?.toString(),
+      composer: data['composer']?.toString(),
       itemType: itemType,
     );
   }

lib/screens/album_screen.dart

@@ -299,9 +299,11 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
       duration: ((data['duration_ms'] as int? ?? 0) / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date'] as String?,
       albumType: data['album_type'] as String?,
       totalTracks: data['total_tracks'] as int?,
+      composer: data['composer']?.toString(),
     );
   }
 

lib/screens/artist_screen.dart

@@ -410,9 +410,11 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
       albumType: data['album_type']?.toString() ?? album?.albumType,
       totalTracks: data['total_tracks'] as int? ?? album?.totalTracks,
+      composer: data['composer']?.toString(),
       source: data['provider_id']?.toString() ?? widget.extensionId,
     );
   }
@@ -1129,9 +1131,11 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
       trackNumber:
           data['track_position'] as int? ?? data['track_number'] as int?,
       discNumber: data['disk_number'] as int? ?? data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: album.releaseDate,
       albumType: album.albumType,
       totalTracks: album.totalTracks,
+      composer: data['composer']?.toString(),
     );
   }
 

lib/screens/home_tab.dart

@@ -1840,6 +1840,7 @@ class _HomeTabState extends ConsumerState<HomeTab>
       duration: item.durationMs ~/ 1000,
       trackNumber: null,
       discNumber: null,
+      totalDiscs: null,
       isrc: null,
       releaseDate: item.releaseDate,
       coverUrl: item.coverUrl,
@@ -4403,7 +4404,10 @@ class _ExtensionAlbumScreenState extends ConsumerState<ExtensionAlbumScreen> {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
+      totalTracks: data['total_tracks'] as int?,
+      composer: data['composer']?.toString(),
       source: widget.extensionId,
     );
   }
@@ -4562,7 +4566,10 @@ class _ExtensionPlaylistScreenState
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
+      totalTracks: data['total_tracks'] as int?,
+      composer: data['composer']?.toString(),
       source: widget.extensionId,
     );
   }
@@ -4739,7 +4746,10 @@ class _ExtensionArtistScreenState extends ConsumerState<ExtensionArtistScreen> {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
+      totalTracks: data['total_tracks'] as int?,
+      composer: data['composer']?.toString(),
       source: (data['provider_id'] ?? widget.extensionId).toString(),
     );
   }

lib/screens/local_album_screen.dart

@@ -1631,7 +1631,12 @@ class _LocalAlbumScreenState extends ConsumerState<LocalAlbumScreen> {
             try {
               await PlatformBridge.safDelete(item.filePath);
             } catch (_) {}
-            await localDb.deleteByPath(item.filePath);
+            await localDb.replaceWithConvertedItem(
+              item: item,
+              newFilePath: safUri,
+              targetFormat: targetFormat,
+              bitrate: bitrate,
+            );
           }
 
           try {
@@ -1643,8 +1648,12 @@ class _LocalAlbumScreenState extends ConsumerState<LocalAlbumScreen> {
             } catch (_) {}
           }
         } else {
-          // Regular file: just remove old entry, rescan will find the new one
+          await localDb.replaceWithConvertedItem(
-          await localDb.deleteByPath(item.filePath);
+            item: item,
+            newFilePath: newPath,
+            targetFormat: targetFormat,
+            bitrate: bitrate,
+          );
         }
 
         successCount++;

lib/screens/playlist_screen.dart

@@ -164,7 +164,10 @@ class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
+      totalTracks: data['total_tracks'] as int?,
+      composer: data['composer']?.toString(),
     );
   }
 

lib/screens/queue_tab.dart

@@ -5853,13 +5853,27 @@ class _QueueTabState extends ConsumerState<QueueTab> {
             final baseName = dotIdx > 0
                 ? oldFileName.substring(0, dotIdx)
                 : oldFileName;
-            final newExt = targetFormat.toLowerCase() == 'opus'
+            String newExt;
-                ? '.opus'
+            String mimeType;
-                : '.mp3';
+            switch (targetFormat.toLowerCase()) {
+              case 'opus':
+                newExt = '.opus';
+                mimeType = 'audio/opus';
+                break;
+              case 'alac':
+                newExt = '.m4a';
+                mimeType = 'audio/mp4';
+                break;
+              case 'flac':
+                newExt = '.flac';
+                mimeType = 'audio/flac';
+                break;
+              default:
+                newExt = '.mp3';
+                mimeType = 'audio/mpeg';
+                break;
+            }
             final newFileName = '$baseName$newExt';
-            final mimeType = targetFormat.toLowerCase() == 'opus'
-                ? 'audio/opus'
-                : 'audio/mpeg';
 
             final safUri = await PlatformBridge.createSafFileFromPath(
               treeUri: treeUri,
@@ -5884,7 +5898,12 @@ class _QueueTabState extends ConsumerState<QueueTab> {
             try {
               await PlatformBridge.safDelete(item.filePath);
             } catch (_) {}
-            await LibraryDatabase.instance.deleteByPath(item.filePath);
+            await LibraryDatabase.instance.replaceWithConvertedItem(
+              item: item.localItem!,
+              newFilePath: safUri,
+              targetFormat: targetFormat,
+              bitrate: bitrate,
+            );
           }
 
           try {
@@ -5903,7 +5922,12 @@ class _QueueTabState extends ConsumerState<QueueTab> {
             clearAudioSpecs: true,
           );
         } else if (item.localItem != null) {
-          await LibraryDatabase.instance.deleteByPath(item.filePath);
+          await LibraryDatabase.instance.replaceWithConvertedItem(
+            item: item.localItem!,
+            newFilePath: newPath,
+            targetFormat: targetFormat,
+            bitrate: bitrate,
+          );
         }
 
         successCount++;

lib/screens/track_metadata_screen.dart

@@ -252,7 +252,7 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
     }
     if (mounted &&
         exists &&
-        !_isLocalItem &&
+        !_isCueVirtualTrack &&
         !_hasLoadedResolvedAudioMetadata) {
       unawaited(_refreshResolvedAudioMetadataFromFile());
     }
@@ -291,8 +291,9 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
   }
 
   Future<void> _refreshResolvedAudioMetadataFromFile() async {
-    if (_isLocalItem ||
+    if ((_isLocalItem && _localLibraryItem == null) ||
-        _downloadItem == null ||
+        (!_isLocalItem && _downloadItem == null) ||
+        _isCueVirtualTrack ||
         _hasLoadedResolvedAudioMetadata) {
       return;
     }
@@ -326,8 +327,23 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
 
       // Resolve label/copyright from file when the model doesn't carry them
       // (e.g. local library items, or download history items without these fields).
+      final resolvedTotalTracks = _readPositiveInt(metadata['total_tracks']);
+      final resolvedTotalDiscs = _readPositiveInt(metadata['total_discs']);
+      final resolvedComposer = metadata['composer']?.toString();
       final resolvedLabel = metadata['label']?.toString();
       final resolvedCopyright = metadata['copyright']?.toString();
+      final needsTotalTracks =
+          resolvedTotalTracks != null &&
+          resolvedTotalTracks > 0 &&
+          totalTracks == null;
+      final needsTotalDiscs =
+          resolvedTotalDiscs != null &&
+          resolvedTotalDiscs > 0 &&
+          totalDiscs == null;
+      final needsComposer =
+          resolvedComposer != null &&
+          resolvedComposer.isNotEmpty &&
+          (composer == null || composer!.isEmpty);
       final needsLabel =
           resolvedLabel != null &&
           resolvedLabel.isNotEmpty &&
@@ -338,14 +354,18 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
           (copyright == null || copyright!.isEmpty);
 
       final shouldPersistResolvedAudioMetadata =
-          resolvedBitDepth != null ||
+          !_isLocalItem &&
-          resolvedSampleRate != null ||
+          (resolvedBitDepth != null ||
-          (isPlaceholderQualityLabel(_quality) && resolvedQuality != null);
+              resolvedSampleRate != null ||
+              (isPlaceholderQualityLabel(_quality) && resolvedQuality != null));
 
       if ((resolvedBitDepth != null ||
               resolvedSampleRate != null ||
               needsAlbum ||
               needsDuration ||
+              needsTotalTracks ||
+              needsTotalDiscs ||
+              needsComposer ||
               needsLabel ||
               needsCopyright ||
               isPlaceholderQualityLabel(_quality)) &&
@@ -359,6 +379,9 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
             if (resolvedSampleRate != null) 'sample_rate': resolvedSampleRate,
             if (needsAlbum) 'album': resolvedAlbum,
             if (needsDuration) 'duration': resolvedDuration,
+            if (needsTotalTracks) 'total_tracks': resolvedTotalTracks,
+            if (needsTotalDiscs) 'total_discs': resolvedTotalDiscs,
+            if (needsComposer) 'composer': resolvedComposer,
             if (needsLabel) 'label': resolvedLabel,
             if (needsCopyright) 'copyright': resolvedCopyright,
           };
@@ -480,6 +503,10 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
         : _downloadItem!.trackNumber;
   }
 
+  int? get totalTracks =>
+      _readPositiveInt(_editedMetadata?['total_tracks']) ??
+      (_isLocalItem ? _localLibraryItem!.totalTracks : null);
+
   int? get discNumber {
     final edited = _editedMetadata?['disc_number'];
     if (edited != null) {
@@ -491,6 +518,10 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
         : _downloadItem!.discNumber;
   }
 
+  int? get totalDiscs =>
+      _readPositiveInt(_editedMetadata?['total_discs']) ??
+      (_isLocalItem ? _localLibraryItem!.totalDiscs : null);
+
   String? get releaseDate =>
       _editedMetadata?['date']?.toString() ??
       (_isLocalItem
@@ -517,10 +548,13 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
       (_isLocalItem ? _localLibraryItem!.genre : _downloadItem!.genre);
   String? get label =>
       _editedMetadata?['label']?.toString() ??
-      (_isLocalItem ? null : _downloadItem!.label);
+      (_isLocalItem ? _localLibraryItem!.label : _downloadItem!.label);
   String? get copyright =>
       _editedMetadata?['copyright']?.toString() ??
-      (_isLocalItem ? null : _downloadItem!.copyright);
+      (_isLocalItem ? _localLibraryItem!.copyright : _downloadItem!.copyright);
+  String? get composer =>
+      _editedMetadata?['composer']?.toString() ??
+      (_isLocalItem ? _localLibraryItem!.composer : null);
   int? get duration =>
       _readPositiveInt(_editedMetadata?['duration']) ??
       (_isLocalItem ? _localLibraryItem!.duration : _downloadItem!.duration);
@@ -1255,8 +1289,12 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
       _MetadataItem(context.l10n.trackAlbum, albumName),
       if (trackNumber != null && trackNumber! > 0)
         _MetadataItem(context.l10n.trackTrackNumber, trackNumber.toString()),
+      if (totalTracks != null && totalTracks! > 0)
+        _MetadataItem('Track Total', totalTracks.toString()),
       if (discNumber != null && discNumber! > 0)
         _MetadataItem(context.l10n.trackDiscNumber, discNumber.toString()),
+      if (totalDiscs != null && totalDiscs! > 0)
+        _MetadataItem('Disc Total', totalDiscs.toString()),
       if (duration != null)
         _MetadataItem(context.l10n.trackDuration, _formatDuration(duration!)),
       if (audioQualityStr != null)
@@ -1269,6 +1307,8 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
         _MetadataItem(context.l10n.trackLabel, label!),
       if (copyright != null && copyright!.isNotEmpty)
         _MetadataItem(context.l10n.trackCopyright, copyright!),
+      if (composer != null && composer!.isNotEmpty)
+        _MetadataItem('Composer', composer!),
       if (isrc != null && isrc!.isNotEmpty) _MetadataItem('ISRC', isrc!),
     ];
 
@@ -2525,12 +2565,15 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
         'album_name': albumName,
         'album_artist': albumArtist ?? artistName,
         'track_number': trackNumber ?? 0,
+        'total_tracks': totalTracks ?? 0,
         'disc_number': discNumber ?? 0,
+        'total_discs': totalDiscs ?? 0,
         'release_date': releaseDate ?? '',
         'isrc': isrc ?? '',
         'genre': genre ?? '',
         'label': label ?? '',
         'copyright': copyright ?? '',
+        'composer': composer ?? '',
         'duration_ms': durationMs,
         'search_online': true,
       };
@@ -2548,11 +2591,14 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
             'album_artist': enriched['album_artist'] ?? albumArtist,
             'date': enriched['release_date'] ?? releaseDate,
             'track_number': enriched['track_number'] ?? trackNumber,
+            'total_tracks': enriched['total_tracks'] ?? totalTracks,
             'disc_number': enriched['disc_number'] ?? discNumber,
+            'total_discs': enriched['total_discs'] ?? totalDiscs,
             'isrc': enriched['isrc'] ?? isrc,
             'genre': enriched['genre'] ?? genre,
             'label': enriched['label'] ?? label,
             'copyright': enriched['copyright'] ?? copyright,
+            'composer': enriched['composer'] ?? composer,
           };
         });
       }
@@ -2989,19 +3035,29 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
   }
 
   Map<String, String> _buildFallbackMetadata() {
+    String formatIndexTag(int number, int? total) {
+      if (total != null && total > 0) {
+        return '$number/$total';
+      }
+      return number.toString();
+    }
+
     return {
       'TITLE': trackName,
       'ARTIST': artistName,
       'ALBUM': albumName,
       if (albumArtist != null && albumArtist!.isNotEmpty)
         'ALBUMARTIST': albumArtist!,
-      if (trackNumber != null) 'TRACKNUMBER': trackNumber.toString(),
+      if (trackNumber != null)
-      if (discNumber != null) 'DISCNUMBER': discNumber.toString(),
+        'TRACKNUMBER': formatIndexTag(trackNumber!, totalTracks),
+      if (discNumber != null)
+        'DISCNUMBER': formatIndexTag(discNumber!, totalDiscs),
       if (releaseDate != null && releaseDate!.isNotEmpty) 'DATE': releaseDate!,
       if (isrc != null && isrc!.isNotEmpty) 'ISRC': isrc!,
       if (genre != null && genre!.isNotEmpty) 'GENRE': genre!,
       if (label != null && label!.isNotEmpty) 'LABEL': label!,
       if (copyright != null && copyright!.isNotEmpty) 'COPYRIGHT': copyright!,
+      if (composer != null && composer!.isNotEmpty) 'COMPOSER': composer!,
     };
   }
 
@@ -3029,12 +3085,26 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
     put('UNSYNCEDLYRICS', source['lyrics']);
 
     final trackNumber = source['track_number'];
+    final totalTracks = source['total_tracks'];
     if (trackNumber != null && trackNumber.toString() != '0') {
-      put('TRACKNUMBER', trackNumber);
+      final trackTag =
+          totalTracks != null &&
+              totalTracks.toString().isNotEmpty &&
+              totalTracks.toString() != '0'
+          ? '${trackNumber.toString()}/${totalTracks.toString()}'
+          : trackNumber;
+      put('TRACKNUMBER', trackTag);
     }
     final discNumber = source['disc_number'];
+    final totalDiscs = source['total_discs'];
     if (discNumber != null && discNumber.toString() != '0') {
-      put('DISCNUMBER', discNumber);
+      final discTag =
+          totalDiscs != null &&
+              totalDiscs.toString().isNotEmpty &&
+              totalDiscs.toString() != '0'
+          ? '${discNumber.toString()}/${totalDiscs.toString()}'
+          : discNumber;
+      put('DISCNUMBER', discTag);
     }
 
     return mapped;
@@ -3859,8 +3929,50 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
       final newQuality = _buildConvertedQualityLabel(targetFormat, bitrate);
 
       if (isSaf) {
-        final treeUri = _downloadItem?.downloadTreeUri;
+        String? treeUri;
-        final relativeDir = _downloadItem?.safRelativeDir ?? '';
+        String relativeDir = '';
+        String oldFileName = '';
+        if (_isLocalItem) {
+          final uri = Uri.parse(cleanFilePath);
+          final pathSegments = uri.pathSegments;
+          final treeIdx = pathSegments.indexOf('tree');
+          final docIdx = pathSegments.indexOf('document');
+          if (treeIdx >= 0 && treeIdx + 1 < pathSegments.length) {
+            final treeId = pathSegments[treeIdx + 1];
+            treeUri =
+                'content://${uri.authority}/tree/${Uri.encodeComponent(treeId)}';
+          }
+          if (docIdx >= 0 && docIdx + 1 < pathSegments.length) {
+            final docPath = Uri.decodeFull(pathSegments[docIdx + 1]);
+            final slashIdx = docPath.lastIndexOf('/');
+            if (slashIdx >= 0) {
+              oldFileName = docPath.substring(slashIdx + 1);
+              final treeId = treeIdx >= 0 && treeIdx + 1 < pathSegments.length
+                  ? Uri.decodeFull(pathSegments[treeIdx + 1])
+                  : '';
+              if (treeId.isNotEmpty && docPath.startsWith(treeId)) {
+                final afterTree = docPath.substring(treeId.length);
+                final trimmed = afterTree.startsWith('/')
+                    ? afterTree.substring(1)
+                    : afterTree;
+                final lastSlash = trimmed.lastIndexOf('/');
+                relativeDir = lastSlash >= 0
+                    ? trimmed.substring(0, lastSlash)
+                    : '';
+              }
+            } else {
+              oldFileName = docPath;
+            }
+          }
+        } else {
+          treeUri = _downloadItem?.downloadTreeUri;
+          relativeDir = _downloadItem?.safRelativeDir ?? '';
+          oldFileName =
+              (_downloadItem?.safFileName != null &&
+                  _downloadItem!.safFileName!.isNotEmpty)
+              ? _downloadItem!.safFileName!
+              : _extractFileNameFromPathOrUri(cleanFilePath);
+        }
         if (treeUri == null || treeUri.isEmpty) {
           try {
             await File(newPath).delete();
@@ -3879,11 +3991,6 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
           return;
         }
 
-        final oldFileName =
-            (_downloadItem?.safFileName != null &&
-                _downloadItem!.safFileName!.isNotEmpty)
-            ? _downloadItem!.safFileName!
-            : _extractFileNameFromPathOrUri(cleanFilePath);
         final dotIdx = oldFileName.lastIndexOf('.');
         final baseName = dotIdx > 0
             ? oldFileName.substring(0, dotIdx)
@@ -3952,6 +4059,14 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
             clearAudioSpecs: true,
           );
           await ref.read(downloadHistoryProvider.notifier).reloadFromStorage();
+        } else {
+          await LibraryDatabase.instance.replaceWithConvertedItem(
+            item: _localLibraryItem!,
+            newFilePath: safUri,
+            targetFormat: targetFormat,
+            bitrate: bitrate,
+          );
+          await ref.read(localLibraryProvider.notifier).reloadFromStorage();
         }
 
         try {
@@ -3971,6 +4086,14 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
             clearAudioSpecs: true,
           );
           await ref.read(downloadHistoryProvider.notifier).reloadFromStorage();
+        } else {
+          await LibraryDatabase.instance.replaceWithConvertedItem(
+            item: _localLibraryItem!,
+            newFilePath: newPath,
+            targetFormat: targetFormat,
+            bitrate: bitrate,
+          );
+          await ref.read(localLibraryProvider.notifier).reloadFromStorage();
         }
       }
 
@@ -4021,13 +4144,17 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
       'date': val('date', releaseDate),
       'track_number': (fileMetadata?['track_number'] ?? trackNumber ?? '')
           .toString(),
+      'total_tracks': (fileMetadata?['total_tracks'] ?? totalTracks ?? '')
+          .toString(),
       'disc_number': (fileMetadata?['disc_number'] ?? discNumber ?? '')
           .toString(),
+      'total_discs': (fileMetadata?['total_discs'] ?? totalDiscs ?? '')
+          .toString(),
       'genre': val('genre', genre),
       'isrc': val('isrc', isrc),
       'label': val('label', label),
       'copyright': val('copyright', copyright),
-      'composer': fileMetadata?['composer']?.toString() ?? '',
+      'composer': val('composer', composer),
       'comment': fileMetadata?['comment']?.toString() ?? '',
     };
 
@@ -4314,11 +4441,14 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
     'album_artist': 'album_artist',
     'date': 'date',
     'track_number': 'track_number',
+    'total_tracks': 'total_tracks',
     'disc_number': 'disc_number',
+    'total_discs': 'total_discs',
     'genre': 'genre',
     'isrc': 'isrc',
     'label': 'label',
     'copyright': 'copyright',
+    'composer': 'composer',
     'cover': 'cover',
   };
 
@@ -4328,7 +4458,9 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
   late final TextEditingController _albumArtistCtrl;
   late final TextEditingController _dateCtrl;
   late final TextEditingController _trackNumCtrl;
+  late final TextEditingController _trackTotalCtrl;
   late final TextEditingController _discNumCtrl;
+  late final TextEditingController _discTotalCtrl;
   late final TextEditingController _genreCtrl;
   late final TextEditingController _isrcCtrl;
   late final TextEditingController _labelCtrl;
@@ -4516,8 +4648,12 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
         return l10n.editMetadataFieldDate;
       case 'track_number':
         return l10n.editMetadataFieldTrackNum;
+      case 'total_tracks':
+        return 'Track Total';
       case 'disc_number':
         return l10n.editMetadataFieldDiscNum;
+      case 'total_discs':
+        return 'Disc Total';
       case 'genre':
         return l10n.editMetadataFieldGenre;
       case 'isrc':
@@ -4526,6 +4662,8 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
         return l10n.editMetadataFieldLabel;
       case 'copyright':
         return l10n.editMetadataFieldCopyright;
+      case 'composer':
+        return 'Composer';
       case 'cover':
         return l10n.editMetadataFieldCover;
       default:
@@ -4547,8 +4685,12 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
         return _dateCtrl;
       case 'track_number':
         return _trackNumCtrl;
+      case 'total_tracks':
+        return _trackTotalCtrl;
       case 'disc_number':
         return _discNumCtrl;
+      case 'total_discs':
+        return _discTotalCtrl;
       case 'genre':
         return _genreCtrl;
       case 'isrc':
@@ -4557,6 +4699,8 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
         return _labelCtrl;
       case 'copyright':
         return _copyrightCtrl;
+      case 'composer':
+        return _composerCtrl;
       default:
         return null;
     }
@@ -4722,11 +4866,14 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
     put('album_artist', track['album_artist']);
     put('date', track['release_date']);
     put('track_number', track['track_number']);
+    put('total_tracks', track['total_tracks']);
     put('disc_number', track['disc_number']);
+    put('total_discs', track['total_discs']);
     put('isrc', track['isrc']);
     put('genre', track['genre']);
     put('label', track['label']);
     put('copyright', track['copyright']);
+    put('composer', track['composer']);
   }
 
   Future<_ResolvedAutoFillTrack?> _resolveAutoFillTrackFromIdentifiers(
@@ -4927,8 +5074,11 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
         'album_artist': (selectedBest['album_artist'] ?? '').toString(),
         'date': (selectedBest['release_date'] ?? '').toString(),
         'track_number': (selectedBest['track_number'] ?? '').toString(),
+        'total_tracks': (selectedBest['total_tracks'] ?? '').toString(),
         'disc_number': (selectedBest['disc_number'] ?? '').toString(),
+        'total_discs': (selectedBest['total_discs'] ?? '').toString(),
         'isrc': (selectedBest['isrc'] ?? '').toString(),
+        'composer': (selectedBest['composer'] ?? '').toString(),
       };
       _mergeOnlineTrackData(enriched, selectedBest);
 
@@ -4937,7 +5087,8 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
       final needsExtended =
           _autoFillFields.contains('genre') ||
           _autoFillFields.contains('label') ||
-          _autoFillFields.contains('copyright');
+          _autoFillFields.contains('copyright') ||
+          _autoFillFields.contains('composer');
 
       final rawSpotifyId = _extractRawSpotifyTrackId(selectedBest);
 
@@ -5099,7 +5250,9 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
     _albumArtistCtrl = TextEditingController(text: v['album_artist'] ?? '');
     _dateCtrl = TextEditingController(text: v['date'] ?? '');
     _trackNumCtrl = TextEditingController(text: v['track_number'] ?? '');
+    _trackTotalCtrl = TextEditingController(text: v['total_tracks'] ?? '');
     _discNumCtrl = TextEditingController(text: v['disc_number'] ?? '');
+    _discTotalCtrl = TextEditingController(text: v['total_discs'] ?? '');
     _genreCtrl = TextEditingController(text: v['genre'] ?? '');
     _isrcCtrl = TextEditingController(text: v['isrc'] ?? '');
     _labelCtrl = TextEditingController(text: v['label'] ?? '');
@@ -5119,7 +5272,9 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
     _albumArtistCtrl.dispose();
     _dateCtrl.dispose();
     _trackNumCtrl.dispose();
+    _trackTotalCtrl.dispose();
     _discNumCtrl.dispose();
+    _discTotalCtrl.dispose();
     _genreCtrl.dispose();
     _isrcCtrl.dispose();
     _labelCtrl.dispose();
@@ -5139,7 +5294,9 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
       'album_artist': _albumArtistCtrl.text,
       'date': _dateCtrl.text,
       'track_number': _trackNumCtrl.text,
+      'track_total': _trackTotalCtrl.text,
       'disc_number': _discNumCtrl.text,
+      'disc_total': _discTotalCtrl.text,
       'genre': _genreCtrl.text,
       'isrc': _isrcCtrl.text,
       'label': _labelCtrl.text,
@@ -5191,12 +5348,18 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
           'TRACKNUMBER':
               (metadata['track_number']?.isNotEmpty == true &&
                   metadata['track_number'] != '0')
-              ? metadata['track_number']!
+              ? (metadata['track_total']?.isNotEmpty == true &&
+                        metadata['track_total'] != '0'
+                    ? '${metadata['track_number']}/${metadata['track_total']}'
+                    : metadata['track_number']!)
               : '',
           'DISCNUMBER':
               (metadata['disc_number']?.isNotEmpty == true &&
                   metadata['disc_number'] != '0')
-              ? metadata['disc_number']!
+              ? (metadata['disc_total']?.isNotEmpty == true &&
+                        metadata['disc_total'] != '0'
+                    ? '${metadata['disc_number']}/${metadata['disc_total']}'
+                    : metadata['disc_number']!)
               : '',
           'GENRE': metadata['genre'] ?? '',
           'ISRC': metadata['isrc'] ?? '',
@@ -5409,6 +5572,18 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
                         ),
                       ),
                       const SizedBox(width: 12),
+                      Expanded(
+                        child: _field(
+                          'Track Total',
+                          _trackTotalCtrl,
+                          keyboard: TextInputType.number,
+                        ),
+                      ),
+                    ],
+                  ),
+                  const SizedBox(height: 12),
+                  Row(
+                    children: [
                       Expanded(
                         child: _field(
                           'Disc #',
@@ -5416,6 +5591,14 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
                           keyboard: TextInputType.number,
                         ),
                       ),
+                      const SizedBox(width: 12),
+                      Expanded(
+                        child: _field(
+                          'Disc Total',
+                          _discTotalCtrl,
+                          keyboard: TextInputType.number,
+                        ),
+                      ),
                     ],
                   ),
                   _field('Genre', _genreCtrl),

lib/services/download_request_payload.dart

@@ -17,6 +17,7 @@ class DownloadRequestPayload {
   final int trackNumber;
   final int discNumber;
   final int totalTracks;
+  final int totalDiscs;
   final String releaseDate;
   final String itemId;
   final int durationMs;
@@ -24,6 +25,7 @@ class DownloadRequestPayload {
   final String genre;
   final String label;
   final String copyright;
+  final String composer;
   final String tidalId;
   final String qobuzId;
   final String deezerId;
@@ -56,6 +58,7 @@ class DownloadRequestPayload {
     this.trackNumber = 0,
     this.discNumber = 0,
     this.totalTracks = 1,
+    this.totalDiscs = 0,
     this.releaseDate = '',
     this.itemId = '',
     this.durationMs = 0,
@@ -63,6 +66,7 @@ class DownloadRequestPayload {
     this.genre = '',
     this.label = '',
     this.copyright = '',
+    this.composer = '',
     this.tidalId = '',
     this.qobuzId = '',
     this.deezerId = '',
@@ -97,6 +101,7 @@ class DownloadRequestPayload {
       'track_number': trackNumber,
       'disc_number': discNumber,
       'total_tracks': totalTracks,
+      'total_discs': totalDiscs,
       'release_date': releaseDate,
       'item_id': itemId,
       'duration_ms': durationMs,
@@ -104,6 +109,7 @@ class DownloadRequestPayload {
       'genre': genre,
       'label': label,
       'copyright': copyright,
+      'composer': composer,
       'tidal_id': tidalId,
       'qobuz_id': qobuzId,
       'deezer_id': deezerId,
@@ -142,6 +148,7 @@ class DownloadRequestPayload {
       trackNumber: trackNumber,
       discNumber: discNumber,
       totalTracks: totalTracks,
+      totalDiscs: totalDiscs,
       releaseDate: releaseDate,
       itemId: itemId,
       durationMs: durationMs,
@@ -149,6 +156,7 @@ class DownloadRequestPayload {
       genre: genre,
       label: label,
       copyright: copyright,
+      composer: composer,
       tidalId: tidalId,
       qobuzId: qobuzId,
       deezerId: deezerId,

lib/services/ffmpeg_service.dart

@@ -1311,28 +1311,38 @@ class FFmpegService {
     cmdBuffer.write('-v error -hide_banner ');
     cmdBuffer.write('-i "$m4aPath" ');
 
-    final hasCover = coverPath != null && await File(coverPath).exists();
+    final normalizedCoverPath = coverPath?.trim();
+    final hasCover =
+        normalizedCoverPath != null &&
+        normalizedCoverPath.isNotEmpty &&
+        await File(normalizedCoverPath).exists();
     if (hasCover) {
-      cmdBuffer.write('-i "$coverPath" ');
+      cmdBuffer.write('-i "$normalizedCoverPath" ');
     }
 
-    cmdBuffer.write('-map 0:a ');
+    final preserveExistingStreams = preserveMetadata && !hasCover;
+    if (preserveExistingStreams) {
+      // When no replacement cover is provided, preserve all input streams so
+      // the existing attached artwork is not dropped during the metadata rewrite.
+      cmdBuffer.write('-map 0 -c copy ');
+    } else {
+      cmdBuffer.write('-map 0:a -c:a copy ');
+    }
     cmdBuffer.write(
       preserveMetadata ? '-map_metadata 0 ' : '-map_metadata -1 ',
     );
 
-    // For M4A/MP4, cover art is mapped as a video stream and stored in the
+    // For M4A cover replacements, mark the image as an attached picture so the
-    // 'covr' atom automatically by FFmpeg. The '-disposition attached_pic'
+    // mp4 muxer writes a proper covr atom instead of a generic MJPEG video track.
-    // flag is only valid for Matroska/WebM containers and must NOT be used here.
+    // Force the mp4 muxer because the default ipod muxer (auto-selected for .m4a)
-    // Force the mp4 muxer when cover art is present because the default ipod
+    // does not register a codec tag for mjpeg on FFmpeg 8.0+.
-    // muxer (auto-selected for .m4a) does not register a codec tag for mjpeg,
-    // causing "codec not currently supported in container" on FFmpeg 8.0+.
     if (hasCover) {
-      cmdBuffer.write('-map 1:v -c:v copy -f mp4 ');
+      cmdBuffer.write('-map 1:v -c:v copy -disposition:v:0 attached_pic ');
+      cmdBuffer.write('-metadata:s:v title="Album cover" ');
+      cmdBuffer.write('-metadata:s:v comment="Cover (front)" ');
+      cmdBuffer.write('-f mp4 ');
     }
 
-    cmdBuffer.write('-c:a copy ');
-
     if (metadata != null) {
       final m4aMetadata = _convertToM4aTags(metadata);
       for (final entry in m4aMetadata.entries) {
@@ -1760,9 +1770,13 @@ class FFmpegService {
           if (value != '0') vorbis['DISCNUMBER'] = value;
           break;
         case 'DATE':
-        case 'YEAR':
           vorbis['DATE'] = value;
           break;
+        case 'YEAR':
+          if (!vorbis.containsKey('DATE') || vorbis['DATE']!.isEmpty) {
+            vorbis['DATE'] = value;
+          }
+          break;
         case 'GENRE':
           vorbis['GENRE'] = value;
           break;
@@ -1921,9 +1935,13 @@ class FFmpegService {
           m4aMap['disc'] = value;
           break;
         case 'DATE':
-        case 'YEAR':
           m4aMap['date'] = value;
           break;
+        case 'YEAR':
+          if (!m4aMap.containsKey('date') || m4aMap['date']!.isEmpty) {
+            m4aMap['date'] = value;
+          }
+          break;
         case 'GENRE':
           m4aMap['genre'] = value;
           break;
@@ -2004,9 +2022,13 @@ class FFmpegService {
           }
           break;
         case 'DATE':
-        case 'YEAR':
           id3Map['date'] = value;
           break;
+        case 'YEAR':
+          if (!id3Map.containsKey('date') || id3Map['date']!.isEmpty) {
+            id3Map['date'] = value;
+          }
+          break;
         case 'ISRC':
           id3Map['TSRC'] = value;
           break;

lib/services/library_database.dart

@@ -20,13 +20,18 @@ class LocalLibraryItem {
   final int? fileModTime;
   final String? isrc;
   final int? trackNumber;
+  final int? totalTracks;
   final int? discNumber;
+  final int? totalDiscs;
   final int? duration;
   final String? releaseDate;
   final int? bitDepth;
   final int? sampleRate;
   final int? bitrate; // kbps, for lossy formats (mp3, opus, ogg)
   final String? genre;
+  final String? composer;
+  final String? label;
+  final String? copyright;
   final String? format; // flac, mp3, opus, m4a
 
   const LocalLibraryItem({
@@ -41,13 +46,18 @@ class LocalLibraryItem {
     this.fileModTime,
     this.isrc,
     this.trackNumber,
+    this.totalTracks,
     this.discNumber,
+    this.totalDiscs,
     this.duration,
     this.releaseDate,
     this.bitDepth,
     this.sampleRate,
     this.bitrate,
     this.genre,
+    this.composer,
+    this.label,
+    this.copyright,
     this.format,
   });
 
@@ -63,13 +73,18 @@ class LocalLibraryItem {
     'fileModTime': fileModTime,
     'isrc': isrc,
     'trackNumber': trackNumber,
+    'totalTracks': totalTracks,
     'discNumber': discNumber,
+    'totalDiscs': totalDiscs,
     'duration': duration,
     'releaseDate': releaseDate,
     'bitDepth': bitDepth,
     'sampleRate': sampleRate,
     'bitrate': bitrate,
     'genre': genre,
+    'composer': composer,
+    'label': label,
+    'copyright': copyright,
     'format': format,
   };
 
@@ -85,14 +100,19 @@ class LocalLibraryItem {
         scannedAt: DateTime.parse(json['scannedAt'] as String),
         fileModTime: (json['fileModTime'] as num?)?.toInt(),
         isrc: json['isrc'] as String?,
-        trackNumber: json['trackNumber'] as int?,
+        trackNumber: (json['trackNumber'] as num?)?.toInt(),
-        discNumber: json['discNumber'] as int?,
+        totalTracks: (json['totalTracks'] as num?)?.toInt(),
-        duration: json['duration'] as int?,
+        discNumber: (json['discNumber'] as num?)?.toInt(),
+        totalDiscs: (json['totalDiscs'] as num?)?.toInt(),
+        duration: (json['duration'] as num?)?.toInt(),
         releaseDate: json['releaseDate'] as String?,
-        bitDepth: json['bitDepth'] as int?,
+        bitDepth: (json['bitDepth'] as num?)?.toInt(),
-        sampleRate: json['sampleRate'] as int?,
+        sampleRate: (json['sampleRate'] as num?)?.toInt(),
         bitrate: (json['bitrate'] as num?)?.toInt(),
         genre: json['genre'] as String?,
+        composer: json['composer'] as String?,
+        label: json['label'] as String?,
+        copyright: json['copyright'] as String?,
         format: json['format'] as String?,
       );
 
@@ -122,7 +142,7 @@ class LibraryDatabase {
 
     return await openDatabase(
       path,
-      version: 4,
+      version: 6,
       onConfigure: (db) async {
         await db.rawQuery('PRAGMA journal_mode = WAL');
         await db.execute('PRAGMA synchronous = NORMAL');
@@ -148,13 +168,18 @@ class LibraryDatabase {
         file_mod_time INTEGER,
         isrc TEXT,
         track_number INTEGER,
+        total_tracks INTEGER,
         disc_number INTEGER,
+        total_discs INTEGER,
         duration INTEGER,
         release_date TEXT,
         bit_depth INTEGER,
         sample_rate INTEGER,
         bitrate INTEGER,
         genre TEXT,
+        composer TEXT,
+        label TEXT,
+        copyright TEXT,
         format TEXT
       )
     ''');
@@ -190,6 +215,19 @@ class LibraryDatabase {
       await db.execute('ALTER TABLE library ADD COLUMN bitrate INTEGER');
       _log.i('Added bitrate column for lossy format quality');
     }
+
+    if (oldVersion < 5) {
+      await db.execute('ALTER TABLE library ADD COLUMN label TEXT');
+      await db.execute('ALTER TABLE library ADD COLUMN copyright TEXT');
+      _log.i('Added label/copyright columns');
+    }
+
+    if (oldVersion < 6) {
+      await db.execute('ALTER TABLE library ADD COLUMN total_tracks INTEGER');
+      await db.execute('ALTER TABLE library ADD COLUMN total_discs INTEGER');
+      await db.execute('ALTER TABLE library ADD COLUMN composer TEXT');
+      _log.i('Added total_tracks/total_discs/composer columns');
+    }
   }
 
   Map<String, dynamic> _jsonToDbRow(Map<String, dynamic> json) {
@@ -205,13 +243,18 @@ class LibraryDatabase {
       'file_mod_time': json['fileModTime'],
       'isrc': json['isrc'],
       'track_number': json['trackNumber'],
+      'total_tracks': json['totalTracks'],
       'disc_number': json['discNumber'],
+      'total_discs': json['totalDiscs'],
       'duration': json['duration'],
       'release_date': json['releaseDate'],
       'bit_depth': json['bitDepth'],
       'sample_rate': json['sampleRate'],
       'bitrate': json['bitrate'],
       'genre': json['genre'],
+      'composer': json['composer'],
+      'label': json['label'],
+      'copyright': json['copyright'],
       'format': json['format'],
     };
   }
@@ -229,13 +272,18 @@ class LibraryDatabase {
       'fileModTime': row['file_mod_time'],
       'isrc': row['isrc'],
       'trackNumber': row['track_number'],
+      'totalTracks': row['total_tracks'],
       'discNumber': row['disc_number'],
+      'totalDiscs': row['total_discs'],
       'duration': row['duration'],
       'releaseDate': row['release_date'],
       'bitDepth': row['bit_depth'],
       'sampleRate': row['sample_rate'],
       'bitrate': row['bitrate'],
       'genre': row['genre'],
+      'composer': row['composer'],
+      'label': row['label'],
+      'copyright': row['copyright'],
       'format': row['format'],
     };
   }
@@ -383,6 +431,45 @@ class LibraryDatabase {
     await db.delete('library', where: 'file_path = ?', whereArgs: [filePath]);
   }
 
+  Future<void> replaceWithConvertedItem({
+    required LocalLibraryItem item,
+    required String newFilePath,
+    required String targetFormat,
+    required String bitrate,
+  }) async {
+    final db = await database;
+    final stat = await fileStat(newFilePath);
+    final now = DateTime.now();
+    final normalizedFormat = _normalizeConvertedFormat(targetFormat);
+    final updated = item.toJson()
+      ..['id'] = _generateLibraryId(newFilePath)
+      ..['filePath'] = newFilePath
+      ..['scannedAt'] = now.toIso8601String()
+      ..['fileModTime'] = stat?.modified?.millisecondsSinceEpoch
+      ..['format'] = normalizedFormat
+      ..['bitrate'] = _convertedBitrate(
+        targetFormat: targetFormat,
+        bitrate: bitrate,
+      );
+
+    if (normalizedFormat == 'mp3' || normalizedFormat == 'opus') {
+      updated['bitDepth'] = null;
+    }
+
+    await db.transaction((txn) async {
+      await txn.delete(
+        'library',
+        where: 'id = ? OR file_path = ?',
+        whereArgs: [item.id, item.filePath],
+      );
+      await txn.insert(
+        'library',
+        _jsonToDbRow(updated),
+        conflictAlgorithm: ConflictAlgorithm.replace,
+      );
+    });
+  }
+
   Future<void> delete(String id) async {
     final db = await database;
     await db.delete('library', where: 'id = ?', whereArgs: [id]);
@@ -554,4 +641,43 @@ class LibraryDatabase {
     }
     return totalDeleted;
   }
+
+  String _normalizeConvertedFormat(String targetFormat) {
+    switch (targetFormat.trim().toLowerCase()) {
+      case 'alac':
+        return 'm4a';
+      case 'flac':
+        return 'flac';
+      case 'opus':
+        return 'opus';
+      default:
+        return 'mp3';
+    }
+  }
+
+  int? _convertedBitrate({
+    required String targetFormat,
+    required String bitrate,
+  }) {
+    switch (targetFormat.trim().toLowerCase()) {
+      case 'mp3':
+      case 'opus':
+        final match = RegExp(r'(\d+)').firstMatch(bitrate);
+        return match != null ? int.tryParse(match.group(1)!) : null;
+      default:
+        return null;
+    }
+  }
+
+  String _generateLibraryId(String filePath) {
+    return 'lib_${_hashString(filePath).toRadixString(16)}';
+  }
+
+  int _hashString(String input) {
+    var hash = 5381;
+    for (final codeUnit in input.codeUnits) {
+      hash = (((hash << 5) + hash) + codeUnit) & 0xffffffff;
+    }
+    return hash;
+  }
 }

lib/services/local_track_redownload_service.dart

@@ -142,8 +142,10 @@ class LocalTrackRedownloadService {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
       totalTracks: data['total_tracks'] as int?,
+      composer: data['composer']?.toString(),
       source: data['source']?.toString() ?? data['provider_id']?.toString(),
       albumType: data['album_type']?.toString(),
       itemType: itemType,

lib/utils/lyrics_metadata_helper.dart

@@ -100,12 +100,28 @@ void mergePlatformMetadataForTagEmbed({
   put('UNSYNCEDLYRICS', source['lyrics']);
 
   final trackNumber = source['track_number'];
+  final totalTracks = source['total_tracks'];
   if (trackNumber != null && trackNumber.toString() != '0') {
-    put('TRACKNUMBER', trackNumber);
+    put(
+      'TRACKNUMBER',
+      totalTracks != null &&
+              totalTracks.toString().isNotEmpty &&
+              totalTracks.toString() != '0'
+          ? '${trackNumber.toString()}/${totalTracks.toString()}'
+          : trackNumber,
+    );
   }
 
   final discNumber = source['disc_number'];
+  final totalDiscs = source['total_discs'];
   if (discNumber != null && discNumber.toString() != '0') {
-    put('DISCNUMBER', discNumber);
+    put(
+      'DISCNUMBER',
+      totalDiscs != null &&
+              totalDiscs.toString().isNotEmpty &&
+              totalDiscs.toString() != '0'
+          ? '${discNumber.toString()}/${totalDiscs.toString()}'
+          : discNumber,
+    );
   }
 }

pubspec.yaml

@@ -1,7 +1,7 @@
 name: spotiflac_android
 description: Download Spotify tracks in FLAC from Tidal, Qobuz & Deezer
 publish_to: "none"
-version: 4.2.0+121
+version: 4.2.1+122
 
 environment:
   sdk: ^3.10.0