fix(library): persist lossless bitrate metadata

lib/providers/download_history_provider_maintenance.dart

@@ -275,6 +275,18 @@ extension _HistoryStartupMaintenance on DownloadHistoryNotifier {
   }
 
   bool _shouldBackfillAudioMetadata(DownloadHistoryItem item) {
+    return _needsAverageBitrateBackfill(item) ||
+        _shouldBackfillAudioMetadataIgnoringBitrate(item);
+  }
+
+  bool _needsAverageBitrateBackfill(DownloadHistoryItem item) {
+    return _supportsAudioMetadataProbe(item.filePath) &&
+        (item.bitrate == null || item.bitrate! <= 0) &&
+        item.duration != null &&
+        item.duration! > 0;
+  }
+
+  bool _shouldBackfillAudioMetadataIgnoringBitrate(DownloadHistoryItem item) {
     if (!_supportsAudioMetadataProbe(item.filePath)) {
       return false;
     }
@@ -396,10 +408,9 @@ extension _HistoryStartupMaintenance on DownloadHistoryNotifier {
       final detectedFormat = normalizeAudioFormatValue(
         result['audio_codec']?.toString() ?? result['format']?.toString(),
       );
-      final rawBitrateKbps = readPositiveBitrateKbps(result['bitrate']);
-      final bitrateKbps = isLossyAudioFormat(detectedFormat)
-          ? rawBitrateKbps
-          : null;
+      final bitrateKbps = readPositiveBitrateKbps(
+        result['bitrate'] ?? result['bit_rate'],
+      );
       final quality = resolveDisplayQuality(
         filePath: filePath,
         detectedFormat: detectedFormat,
@@ -496,10 +507,24 @@ extension _HistoryStartupMaintenance on DownloadHistoryNotifier {
       for (final index in selectedIndexes) {
         final item = items[index];
 
-        final probed = await _probeAudioMetadata(
-          item.filePath,
-          fallbackQuality: item.quality,
-        );
+        Map<String, dynamic>? probed;
+        if (_shouldBackfillAudioMetadataIgnoringBitrate(item)) {
+          probed = await _probeAudioMetadata(
+            item.filePath,
+            fallbackQuality: item.quality,
+          );
+        } else if (_needsAverageBitrateBackfill(item)) {
+          // A stat is enough for average bitrate and avoids copying an entire
+          // SAF file to cache merely to update the Library badge.
+          final stat = await fileStat(item.filePath);
+          final bitrate = estimateAverageBitrateKbps(
+            fileSizeBytes: stat?.size,
+            durationSeconds: item.duration,
+          );
+          if (bitrate != null) {
+            probed = {'bitrate': bitrate};
+          }
+        }
         if (probed == null) {
           continue;
         }

lib/providers/download_queue_provider_finalization.dart

@@ -382,7 +382,7 @@ extension _DownloadQueueFinalization on DownloadQueueNotifier {
     if (bitDepth != null) result['actual_bit_depth'] = bitDepth;
     if (sampleRate != null) result['actual_sample_rate'] = sampleRate;
     if (detectedFormat != null) result['audio_codec'] = detectedFormat;
-    if (bitrateKbps != null && isLossyAudioFormat(detectedFormat)) {
+    if (bitrateKbps != null) {
       result['bitrate'] = bitrateKbps;
     }
 

lib/providers/download_queue_provider_native_worker.dart

@@ -50,9 +50,9 @@ extension _DownloadQueueNativeWorker on DownloadQueueNotifier {
         : readPositiveInt(
             result['actual_sample_rate'] ?? result['sample_rate'],
           );
-    final bitrate = isLossy
-        ? readPositiveBitrateKbps(result['actual_bitrate'] ?? result['bitrate'])
-        : null;
+    final bitrate = readPositiveBitrateKbps(
+      result['actual_bitrate'] ?? result['bitrate'],
+    );
     final storedQuality =
         result['quality']?.toString().trim().isNotEmpty == true
         ? result['quality'].toString()
@@ -1023,9 +1023,9 @@ extension _DownloadQueueNativeWorker on DownloadQueueNotifier {
           result['audio_codec']?.toString() ?? result['format']?.toString(),
         ) ??
         normalizeAudioFormatValue(audioFormatForPath(filePath));
-    var actualBitrate = isLossyAudioFormat(actualFormat)
-        ? readPositiveBitrateKbps(result['bitrate'] ?? result['actual_bitrate'])
-        : null;
+    var actualBitrate = readPositiveBitrateKbps(
+      result['bitrate'] ?? result['actual_bitrate'],
+    );
     final resolvedQuality = resolveDisplayQuality(
       filePath: filePath,
       detectedFormat: actualFormat,
@@ -1119,11 +1119,9 @@ extension _DownloadQueueNativeWorker on DownloadQueueNotifier {
       actualFormat =
           normalizeAudioFormatValue(result['audio_codec']?.toString()) ??
           normalizeAudioFormatValue(audioFormatForPath(filePath));
-      actualBitrate = isLossyAudioFormat(actualFormat)
-          ? readPositiveBitrateKbps(
-              result['bitrate'] ?? result['actual_bitrate'],
-            )
-          : null;
+      actualBitrate = readPositiveBitrateKbps(
+        result['bitrate'] ?? result['actual_bitrate'],
+      );
       final finalQuality = resolveDisplayQuality(
         filePath: filePath,
         fileName: variantOutcome.fileName,
@@ -1199,7 +1197,7 @@ extension _DownloadQueueNativeWorker on DownloadQueueNotifier {
                     : context.safFileName,
                 bitDepth: isLossyOutput ? null : actualBitDepth,
                 sampleRate: isLossyOutput ? null : actualSampleRate,
-                bitrate: isLossyOutput ? actualBitrate : null,
+                bitrate: actualBitrate,
                 format: historyFormat,
                 genre: normalizeOptionalString(result['genre'] as String?),
                 label: normalizeOptionalString(result['label'] as String?),

lib/providers/download_queue_provider_single_item.dart

@@ -1481,9 +1481,7 @@ class _DownloadRun {
       int? finalBitDepth = backendBitDepth;
       int? finalSampleRate = backendSampleRate;
       String? finalFormat = backendFormat;
-      int? finalBitrateKbps = isLossyAudioFormat(finalFormat)
-          ? backendBitrateKbps
-          : null;
+      int? finalBitrateKbps = backendBitrateKbps;
       final lowerFilePath = path.toLowerCase();
       final canProbeFinalMetadata =
           path.startsWith('content://') ||
@@ -1525,7 +1523,7 @@ class _DownloadRun {
             final probedBitrateKbps = readPositiveBitrateKbps(
               metadata['bitrate'] ?? metadata['bit_rate'],
             );
-            if (probedBitrateKbps != null && isLossyAudioFormat(finalFormat)) {
+            if (probedBitrateKbps != null) {
               finalBitrateKbps = probedBitrateKbps;
             }
 
@@ -1556,7 +1554,7 @@ class _DownloadRun {
           lowerFilePath.endsWith('.ogg');
       final historyBitDepth = isLossyOutput ? null : finalBitDepth;
       final historySampleRate = isLossyOutput ? null : finalSampleRate;
-      final historyBitrate = isLossyOutput ? finalBitrateKbps : null;
+      final historyBitrate = finalBitrateKbps;
 
       await persistBeforePublishingDownloadCompletion(
         persist: () async {

lib/services/library_database_models.dart

@@ -21,7 +21,7 @@ class LocalLibraryItem {
   final String? releaseDate;
   final int? bitDepth;
   final int? sampleRate;
-  final int? bitrate; // kbps, for lossy formats (mp3, opus, ogg)
+  final int? bitrate; // average kbps for both lossless and lossy audio
   final String? genre;
   final String? composer;
   final String? label;

lib/utils/audio_format_utils.dart

@@ -10,6 +10,24 @@ int? readPositiveBitrateKbps(dynamic value) {
   return kbps >= 16 ? kbps : null;
 }
 
+/// Estimates average stream bitrate without decoding audio. Older SAF-backed
+/// Library rows can therefore be updated with a cheap size query instead of
+/// copying the complete audio file into app cache.
+int? estimateAverageBitrateKbps({
+  required int? fileSizeBytes,
+  required int? durationSeconds,
+}) {
+  if (fileSizeBytes == null ||
+      fileSizeBytes <= 0 ||
+      durationSeconds == null ||
+      durationSeconds <= 0) {
+    return null;
+  }
+  return readPositiveBitrateKbps(
+    (fileSizeBytes * 8 / durationSeconds / 1000).round(),
+  );
+}
+
 String? audioFormatForPath(String? filePath, {String? fileName}) {
   final candidates = <String>[?filePath, ?fileName];
   for (final candidate in candidates) {