fix: merge conflicts and upstream changes merged

octo-fiesta/Services/Common/BaseDownloadService.cs

@@ -4,6 +4,7 @@ using octo_fiesta.Models.Download;
 using octo_fiesta.Models.Search;
 using octo_fiesta.Models.Subsonic;
 using octo_fiesta.Services.Local;
+using octo_fiesta.Services.Subsonic;
 using TagLib;
 using IOFile = System.IO.File;
 
@@ -21,12 +22,30 @@ public abstract class BaseDownloadService : IDownloadService
     protected readonly IMusicMetadataService MetadataService;
     protected readonly SubsonicSettings SubsonicSettings;
     protected readonly ILogger Logger;
+    private readonly IServiceProvider _serviceProvider;
     
     protected readonly string DownloadPath;
+    protected readonly string CachePath;
     
     protected readonly Dictionary<string, DownloadInfo> ActiveDownloads = new();
     protected readonly SemaphoreSlim DownloadLock = new(1, 1);
     
+    /// <summary>
+    /// Lazy-loaded PlaylistSyncService to avoid circular dependency
+    /// </summary>
+    private PlaylistSyncService? _playlistSyncService;
+    protected PlaylistSyncService? PlaylistSyncService
+    {
+        get
+        {
+            if (_playlistSyncService == null)
+            {
+                _playlistSyncService = _serviceProvider.GetService<PlaylistSyncService>();
+            }
+            return _playlistSyncService;
+        }
+    }
+    
     /// <summary>
     /// Provider name (e.g., "deezer", "qobuz")
     /// </summary>
@@ -37,20 +56,28 @@ public abstract class BaseDownloadService : IDownloadService
         ILocalLibraryService localLibraryService,
         IMusicMetadataService metadataService,
         SubsonicSettings subsonicSettings,
+        IServiceProvider serviceProvider,
         ILogger logger)
     {
         Configuration = configuration;
         LocalLibraryService = localLibraryService;
         MetadataService = metadataService;
         SubsonicSettings = subsonicSettings;
+        _serviceProvider = serviceProvider;
         Logger = logger;
         
         DownloadPath = configuration["Library:DownloadPath"] ?? "./downloads";
+        CachePath = PathHelper.GetCachePath();
         
         if (!Directory.Exists(DownloadPath))
         {
             Directory.CreateDirectory(DownloadPath);
         }
+        
+        if (!Directory.Exists(CachePath))
+        {
+            Directory.CreateDirectory(CachePath);
+        }
     }
     
     #region IDownloadService Implementation
@@ -62,7 +89,7 @@ public abstract class BaseDownloadService : IDownloadService
     
     public async Task<Stream> DownloadAndStreamAsync(string externalProvider, string externalId, CancellationToken cancellationToken = default)
     {
-        var localPath = await DownloadSongAsync(externalProvider, externalId, cancellationToken);
+        var localPath = await DownloadSongInternalAsync(externalProvider, externalId, triggerAlbumDownload: true, cancellationToken);
         return IOFile.OpenRead(localPath);
     }
     
@@ -72,6 +99,30 @@ public abstract class BaseDownloadService : IDownloadService
         return info;
     }
     
+    public async Task<string?> GetLocalPathIfExistsAsync(string externalProvider, string externalId)
+    {
+        if (externalProvider != ProviderName)
+        {
+            return null;
+        }
+        
+        // Check local library
+        var localPath = await LocalLibraryService.GetLocalPathForExternalSongAsync(externalProvider, externalId);
+        if (localPath != null && IOFile.Exists(localPath))
+        {
+            return localPath;
+        }
+        
+        // Check cache directory
+        var cachedPath = GetCachedFilePath(externalProvider, externalId);
+        if (cachedPath != null && IOFile.Exists(cachedPath))
+        {
+            return cachedPath;
+        }
+        
+        return null;
+    }
+    
     public abstract Task<bool> IsAvailableAsync();
     
     public void DownloadRemainingAlbumTracksInBackground(string externalProvider, string albumExternalId, string excludeTrackExternalId)
@@ -130,37 +181,86 @@ public abstract class BaseDownloadService : IDownloadService
         }
 
         var songId = $"ext-{externalProvider}-{externalId}";
+        var isCache = SubsonicSettings.StorageMode == StorageMode.Cache;
         
-        // Check if already downloaded
-        var existingPath = await LocalLibraryService.GetLocalPathForExternalSongAsync(externalProvider, externalId);
-        if (existingPath != null && IOFile.Exists(existingPath))
-        {
-            Logger.LogInformation("Song already downloaded: {Path}", existingPath);
-            return existingPath;
-        }
-
-        // Check if download in progress
-        if (ActiveDownloads.TryGetValue(songId, out var activeDownload) && activeDownload.Status == DownloadStatus.InProgress)
-        {
-            Logger.LogInformation("Download already in progress for {SongId}", songId);
-            while (ActiveDownloads.TryGetValue(songId, out activeDownload) && activeDownload.Status == DownloadStatus.InProgress)
-            {
-                await Task.Delay(500, cancellationToken);
-            }
-            
-            if (activeDownload?.Status == DownloadStatus.Completed && activeDownload.LocalPath != null)
-            {
-                return activeDownload.LocalPath;
-            }
-            
-            throw new Exception(activeDownload?.ErrorMessage ?? "Download failed");
-        }
-
+        // Acquire lock BEFORE checking existence to prevent race conditions with concurrent requests
         await DownloadLock.WaitAsync(cancellationToken);
+        
         try
         {
+            // Check if already downloaded (skip for cache mode as we want to check cache folder)
+            if (!isCache)
+            {
+                var existingPath = await LocalLibraryService.GetLocalPathForExternalSongAsync(externalProvider, externalId);
+                if (existingPath != null && IOFile.Exists(existingPath))
+                {
+                    Logger.LogInformation("Song already downloaded: {Path}", existingPath);
+                    return existingPath;
+                }
+            }
+            else
+            {
+                // For cache mode, check if file exists in cache directory
+                var cachedPath = GetCachedFilePath(externalProvider, externalId);
+                if (cachedPath != null && IOFile.Exists(cachedPath))
+                {
+                    Logger.LogInformation("Song found in cache: {Path}", cachedPath);
+                    // Update file access time for cache cleanup logic
+                    IOFile.SetLastAccessTime(cachedPath, DateTime.UtcNow);
+                    return cachedPath;
+                }
+            }
+
+            // Check if download in progress
+            if (ActiveDownloads.TryGetValue(songId, out var activeDownload) && activeDownload.Status == DownloadStatus.InProgress)
+            {
+                Logger.LogInformation("Download already in progress for {SongId}, waiting...", songId);
+                // Release lock while waiting
+                DownloadLock.Release();
+                
+                while (ActiveDownloads.TryGetValue(songId, out activeDownload) && activeDownload.Status == DownloadStatus.InProgress)
+                {
+                    await Task.Delay(500, cancellationToken);
+                }
+                
+                if (activeDownload?.Status == DownloadStatus.Completed && activeDownload.LocalPath != null)
+                {
+                    return activeDownload.LocalPath;
+                }
+                
+                throw new Exception(activeDownload?.ErrorMessage ?? "Download failed");
+            }
+
             // Get metadata
-            var song = await MetadataService.GetSongAsync(externalProvider, externalId);
+            // In Album mode, fetch the full album first to ensure AlbumArtist is correctly set
+            Song? song = null;
+            
+            if (SubsonicSettings.DownloadMode == DownloadMode.Album)
+            {
+                // First try to get the song to extract album ID
+                var tempSong = await MetadataService.GetSongAsync(externalProvider, externalId);
+                if (tempSong != null && !string.IsNullOrEmpty(tempSong.AlbumId))
+                {
+                    var albumExternalId = ExtractExternalIdFromAlbumId(tempSong.AlbumId);
+                    if (!string.IsNullOrEmpty(albumExternalId))
+                    {
+                        // Get full album with correct AlbumArtist
+                        var album = await MetadataService.GetAlbumAsync(externalProvider, albumExternalId);
+                        if (album != null)
+                        {
+                            // Find the track in the album
+                            song = album.Songs.FirstOrDefault(s => s.ExternalId == externalId);
+                        }
+                    }
+                }
+            }
+            
+            // Fallback to individual song fetch if not in Album mode or album fetch failed
+            if (song == null)
+            {
+                song = await MetadataService.GetSongAsync(externalProvider, externalId);
+            }
+            
             if (song == null)
             {
                 throw new Exception("Song not found");
@@ -176,15 +276,35 @@ public abstract class BaseDownloadService : IDownloadService
             };
             ActiveDownloads[songId] = downloadInfo;
 
-            try
+            var localPath = await DownloadTrackAsync(externalId, song, cancellationToken);
+            
+            downloadInfo.Status = DownloadStatus.Completed;
+            downloadInfo.LocalPath = localPath;
+            downloadInfo.CompletedAt = DateTime.UtcNow;
+            
+            song.LocalPath = localPath;
+            
+            // Check if this track belongs to a playlist and update M3U
+            if (PlaylistSyncService != null)
+            {
+                try
+                {
+                    var playlistId = PlaylistSyncService.GetPlaylistIdForTrack(songId);
+                    if (playlistId != null)
+                    {
+                        Logger.LogInformation("Track {SongId} belongs to playlist {PlaylistId}, adding to M3U", songId, playlistId);
+                        await PlaylistSyncService.AddTrackToM3UAsync(playlistId, song, localPath, isFullPlaylistDownload: false);
+                    }
+                }
+                catch (Exception ex)
+                {
+                    Logger.LogWarning(ex, "Failed to update playlist M3U for track {SongId}", songId);
+                }
+            }
+            
+            // Only register and scan if NOT in cache mode
+            if (!isCache)
             {
-                var localPath = await DownloadTrackAsync(externalId, song, cancellationToken);
-                
-                downloadInfo.Status = DownloadStatus.Completed;
-                downloadInfo.LocalPath = localPath;
-                downloadInfo.CompletedAt = DateTime.UtcNow;
-                
-                song.LocalPath = localPath;
                 await LocalLibraryService.RegisterDownloadedSongAsync(song, localPath);
                 
                 // Trigger a Subsonic library rescan (with debounce)
@@ -210,17 +330,24 @@ public abstract class BaseDownloadService : IDownloadService
                         DownloadRemainingAlbumTracksInBackground(externalProvider, albumExternalId, externalId);
                     }
                 }
-                
-                Logger.LogInformation("Download completed: {Path}", localPath);
-                return localPath;
             }
-            catch (Exception ex)
+            else
+            {
+                Logger.LogInformation("Cache mode: skipping library registration and scan");
+            }
+            
+            Logger.LogInformation("Download completed: {Path}", localPath);
+            return localPath;
+        }
+        catch (Exception ex)
+        {
+            if (ActiveDownloads.TryGetValue(songId, out var downloadInfo))
             {
                 downloadInfo.Status = DownloadStatus.Failed;
                 downloadInfo.ErrorMessage = ex.Message;
-                Logger.LogError(ex, "Download failed for {SongId}", songId);
-                throw;
             }
+            Logger.LogError(ex, "Download failed for {SongId}", songId);
+            throw;
         }
         finally
         {
@@ -258,6 +385,23 @@ public abstract class BaseDownloadService : IDownloadService
                     continue;
                 }
 
+                // Check if download is already in progress or recently completed
+                var songId = $"ext-{ProviderName}-{track.ExternalId}";
+                if (ActiveDownloads.TryGetValue(songId, out var activeDownload))
+                {
+                    if (activeDownload.Status == DownloadStatus.InProgress)
+                    {
+                        Logger.LogDebug("Track {TrackId} download already in progress, skipping", track.ExternalId);
+                        continue;
+                    }
+                    
+                    if (activeDownload.Status == DownloadStatus.Completed)
+                    {
+                        Logger.LogDebug("Track {TrackId} already downloaded in this session, skipping", track.ExternalId);
+                        continue;
+                    }
+                }
+
                 Logger.LogInformation("Downloading track '{Title}' from album '{Album}'", track.Title, album.Title);
                 await DownloadSongInternalAsync(ProviderName, track.ExternalId!, triggerAlbumDownload: false, CancellationToken.None);
             }
@@ -401,5 +545,31 @@ public abstract class BaseDownloadService : IDownloadService
         }
     }
     
+    /// <summary>
+    /// Gets the cached file path for a given provider and external ID
+    /// Returns null if no cached file exists
+    /// </summary>
+    protected string? GetCachedFilePath(string provider, string externalId)
+    {
+        try
+        {
+            // Search for cached files matching the pattern: {provider}_{externalId}.*
+            var pattern = $"{provider}_{externalId}.*";
+            var files = Directory.GetFiles(CachePath, pattern, SearchOption.AllDirectories);
+            
+            if (files.Length > 0)
+            {
+                return files[0]; // Return first match
+            }
+            
+            return null;
+        }
+        catch (Exception ex)
+        {
+            Logger.LogWarning(ex, "Failed to search for cached file: {Provider}_{ExternalId}", provider, externalId);
+            return null;
+        }
+    }
+    
     #endregion
 }

octo-fiesta/Services/Common/CacheCleanupService.cs

@@ -0,0 +1,163 @@
+using Microsoft.Extensions.Options;
+using octo_fiesta.Models.Settings;
+
+namespace octo_fiesta.Services.Common;
+
+/// <summary>
+/// Background service that periodically cleans up old cached files
+/// Only runs when StorageMode is set to Cache
+/// </summary>
+public class CacheCleanupService : BackgroundService
+{
+    private readonly IConfiguration _configuration;
+    private readonly SubsonicSettings _subsonicSettings;
+    private readonly ILogger<CacheCleanupService> _logger;
+    private readonly TimeSpan _cleanupInterval = TimeSpan.FromHours(1);
+
+    public CacheCleanupService(
+        IConfiguration configuration,
+        IOptions<SubsonicSettings> subsonicSettings,
+        ILogger<CacheCleanupService> logger)
+    {
+        _configuration = configuration;
+        _subsonicSettings = subsonicSettings.Value;
+        _logger = logger;
+    }
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        // Only run if storage mode is Cache
+        if (_subsonicSettings.StorageMode != StorageMode.Cache)
+        {
+            _logger.LogInformation("CacheCleanupService disabled: StorageMode is not Cache");
+            return;
+        }
+
+        _logger.LogInformation("CacheCleanupService started with cleanup interval of {Interval} and retention of {Hours} hours",
+            _cleanupInterval, _subsonicSettings.CacheDurationHours);
+
+        while (!stoppingToken.IsCancellationRequested)
+        {
+            try
+            {
+                await CleanupOldCachedFilesAsync(stoppingToken);
+                await Task.Delay(_cleanupInterval, stoppingToken);
+            }
+            catch (OperationCanceledException)
+            {
+                // Service is stopping, exit gracefully
+                break;
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Error during cache cleanup");
+                // Continue running even if cleanup fails
+                await Task.Delay(_cleanupInterval, stoppingToken);
+            }
+        }
+
+        _logger.LogInformation("CacheCleanupService stopped");
+    }
+
+    private async Task CleanupOldCachedFilesAsync(CancellationToken cancellationToken)
+    {
+        var cachePath = PathHelper.GetCachePath();
+
+        if (!Directory.Exists(cachePath))
+        {
+            _logger.LogDebug("Cache directory does not exist: {Path}", cachePath);
+            return;
+        }
+
+        var cutoffTime = DateTime.UtcNow.AddHours(-_subsonicSettings.CacheDurationHours);
+        var deletedCount = 0;
+        var totalSize = 0L;
+
+        _logger.LogInformation("Starting cache cleanup: deleting files older than {CutoffTime}", cutoffTime);
+
+        try
+        {
+            // Get all files in cache directory and subdirectories
+            var files = Directory.GetFiles(cachePath, "*.*", SearchOption.AllDirectories);
+
+            foreach (var filePath in files)
+            {
+                if (cancellationToken.IsCancellationRequested)
+                    break;
+
+                try
+                {
+                    var fileInfo = new FileInfo(filePath);
+
+                    // Use last access time to determine if file should be deleted
+                    // This gets updated when a cached file is streamed
+                    if (fileInfo.LastAccessTimeUtc < cutoffTime)
+                    {
+                        var size = fileInfo.Length;
+                        File.Delete(filePath);
+                        deletedCount++;
+                        totalSize += size;
+                        _logger.LogDebug("Deleted cached file: {Path} (last accessed: {LastAccess})",
+                            filePath, fileInfo.LastAccessTimeUtc);
+                    }
+                }
+                catch (Exception ex)
+                {
+                    _logger.LogWarning(ex, "Failed to delete cached file: {Path}", filePath);
+                }
+            }
+
+            // Clean up empty directories
+            await CleanupEmptyDirectoriesAsync(cachePath, cancellationToken);
+
+            if (deletedCount > 0)
+            {
+                var sizeMB = totalSize / (1024.0 * 1024.0);
+                _logger.LogInformation("Cache cleanup completed: deleted {Count} files, freed {Size:F2} MB",
+                    deletedCount, sizeMB);
+            }
+            else
+            {
+                _logger.LogDebug("Cache cleanup completed: no files to delete");
+            }
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Error during cache cleanup");
+        }
+    }
+
+    private async Task CleanupEmptyDirectoriesAsync(string rootPath, CancellationToken cancellationToken)
+    {
+        try
+        {
+            var directories = Directory.GetDirectories(rootPath, "*", SearchOption.AllDirectories)
+                .OrderByDescending(d => d.Length); // Process deepest directories first
+
+            foreach (var directory in directories)
+            {
+                if (cancellationToken.IsCancellationRequested)
+                    break;
+
+                try
+                {
+                    if (!Directory.EnumerateFileSystemEntries(directory).Any())
+                    {
+                        Directory.Delete(directory);
+                        _logger.LogDebug("Deleted empty directory: {Path}", directory);
+                    }
+                }
+                catch (Exception ex)
+                {
+                    _logger.LogWarning(ex, "Failed to delete empty directory: {Path}", directory);
+                }
+            }
+        }
+        catch (Exception ex)
+        {
+            _logger.LogWarning(ex, "Error cleaning up empty directories");
+        }
+
+        await Task.CompletedTask;
+    }
+}

octo-fiesta/Services/Common/PathHelper.cs

@@ -8,6 +8,17 @@ namespace octo_fiesta.Services.Common;
 /// </summary>
 public static class PathHelper
 {
+    /// <summary>
+    /// Gets the cache directory path for temporary file storage.
+    /// Uses system temp directory combined with octo-fiesta-cache subfolder.
+    /// Respects TMPDIR environment variable on Linux/macOS.
+    /// </summary>
+    /// <returns>Full path to the cache directory.</returns>
+    public static string GetCachePath()
+    {
+        return Path.Combine(Path.GetTempPath(), "octo-fiesta-cache");
+    }
+    
     /// <summary>
     /// Builds the output path for a downloaded track following the Artist/Album/Track structure.
     /// </summary>

octo-fiesta/Services/Common/PlaylistIdHelper.cs

@@ -0,0 +1,76 @@
+namespace octo_fiesta.Services.Common;
+
+/// <summary>
+/// Helper class for handling external playlist IDs.
+/// Playlist IDs use the format: "pl-{provider}-{externalId}"
+/// Example: "pl-deezer-123456", "pl-qobuz-789"
+/// </summary>
+public static class PlaylistIdHelper
+{
+    private const string PlaylistPrefix = "pl-";
+    
+    /// <summary>
+    /// Checks if an ID represents an external playlist.
+    /// </summary>
+    /// <param name="id">The ID to check</param>
+    /// <returns>True if the ID starts with "pl-", false otherwise</returns>
+    public static bool IsExternalPlaylist(string? id)
+    {
+        return !string.IsNullOrEmpty(id) && id.StartsWith(PlaylistPrefix, StringComparison.OrdinalIgnoreCase);
+    }
+    
+    /// <summary>
+    /// Parses a playlist ID to extract provider and external ID.
+    /// </summary>
+    /// <param name="id">The playlist ID in format "pl-{provider}-{externalId}"</param>
+    /// <returns>A tuple containing (provider, externalId)</returns>
+    /// <exception cref="ArgumentException">Thrown if the ID format is invalid</exception>
+    public static (string provider, string externalId) ParsePlaylistId(string id)
+    {
+        if (!IsExternalPlaylist(id))
+        {
+            throw new ArgumentException($"Invalid playlist ID format. Expected 'pl-{{provider}}-{{externalId}}', got '{id}'", nameof(id));
+        }
+        
+        // Remove "pl-" prefix
+        var withoutPrefix = id.Substring(PlaylistPrefix.Length);
+        
+        // Split by first dash to get provider and externalId
+        var dashIndex = withoutPrefix.IndexOf('-');
+        if (dashIndex == -1)
+        {
+            throw new ArgumentException($"Invalid playlist ID format. Expected 'pl-{{provider}}-{{externalId}}', got '{id}'", nameof(id));
+        }
+        
+        var provider = withoutPrefix.Substring(0, dashIndex);
+        var externalId = withoutPrefix.Substring(dashIndex + 1);
+        
+        if (string.IsNullOrEmpty(provider) || string.IsNullOrEmpty(externalId))
+        {
+            throw new ArgumentException($"Invalid playlist ID format. Provider or external ID is empty in '{id}'", nameof(id));
+        }
+        
+        return (provider, externalId);
+    }
+    
+    /// <summary>
+    /// Creates a playlist ID from provider and external ID.
+    /// </summary>
+    /// <param name="provider">The provider name (e.g., "deezer", "qobuz")</param>
+    /// <param name="externalId">The external ID from the provider</param>
+    /// <returns>A playlist ID in format "pl-{provider}-{externalId}"</returns>
+    public static string CreatePlaylistId(string provider, string externalId)
+    {
+        if (string.IsNullOrEmpty(provider))
+        {
+            throw new ArgumentException("Provider cannot be null or empty", nameof(provider));
+        }
+        
+        if (string.IsNullOrEmpty(externalId))
+        {
+            throw new ArgumentException("External ID cannot be null or empty", nameof(externalId));
+        }
+        
+        return $"{PlaylistPrefix}{provider.ToLowerInvariant()}-{externalId}";
+    }
+}

octo-fiesta/Services/Deezer/DeezerDownloadService.cs

@@ -11,6 +11,7 @@ using octo_fiesta.Models.Search;
 using octo_fiesta.Models.Subsonic;
 using octo_fiesta.Services.Local;
 using octo_fiesta.Services.Common;
+using octo_fiesta.Services.Subsonic;
 using Microsoft.Extensions.Options;
 using IOFile = System.IO.File;
 
@@ -50,8 +51,9 @@ public class DeezerDownloadService : BaseDownloadService
         IMusicMetadataService metadataService,
         IOptions<SubsonicSettings> subsonicSettings,
         IOptions<DeezerSettings> deezerSettings,
+        IServiceProvider serviceProvider,
         ILogger<DeezerDownloadService> logger)
-        : base(configuration, localLibraryService, metadataService, subsonicSettings.Value, logger)
+        : base(configuration, localLibraryService, metadataService, subsonicSettings.Value, serviceProvider, logger)
     {
         _httpClient = httpClientFactory.CreateClient();
         
@@ -109,7 +111,8 @@ public class DeezerDownloadService : BaseDownloadService
 
         // Build organized folder structure: Artist/Album/Track using AlbumArtist (fallback to Artist for singles)
         var artistForPath = song.AlbumArtist ?? song.Artist;
-        var outputPath = PathHelper.BuildTrackPath(DownloadPath, artistForPath, song.Album, song.Title, song.Track, extension);
+        var basePath = SubsonicSettings.StorageMode == StorageMode.Cache ? CachePath : DownloadPath;
+        var outputPath = PathHelper.BuildTrackPath(basePath, artistForPath, song.Album, song.Title, song.Track, extension);
         
         // Create directories if they don't exist
         var albumFolder = Path.GetDirectoryName(outputPath)!;

octo-fiesta/Services/Deezer/DeezerMetadataService.cs

@@ -229,8 +229,14 @@ public class DeezerMetadataService : IMusicMetadataService
             int trackIndex = 1;
             foreach (var track in tracksData.EnumerateArray())
             {
-                // Pass the index as fallback for track_position (Deezer doesn't include it in album tracks)
-                var song = ParseDeezerTrack(track, trackIndex);
+                // Pass the album artist to ensure proper folder organization
+                var song = ParseDeezerTrack(track, trackIndex, album.Artist);
+                
+                // Ensure album metadata is set (tracks in album response may not have full album object)
+                song.Album = album.Title;
+                song.AlbumId = album.Id;
+                song.AlbumArtist = album.Artist;
+                
                 if (ShouldIncludeSong(song))
                 {
                     album.Songs.Add(song);
@@ -283,7 +289,7 @@ public class DeezerMetadataService : IMusicMetadataService
         return albums;
     }
 
-    private Song ParseDeezerTrack(JsonElement track, int? fallbackTrackNumber = null)
+    private Song ParseDeezerTrack(JsonElement track, int? fallbackTrackNumber = null, string? albumArtist = null)
     {
         var externalId = track.GetProperty("id").GetInt64().ToString();
         
@@ -321,6 +327,7 @@ public class DeezerMetadataService : IMusicMetadataService
                           albumForCover.TryGetProperty("cover_medium", out var cover)
                 ? cover.GetString()
                 : null,
+            AlbumArtist = albumArtist,
             IsLocal = false,
             ExternalProvider = "deezer",
             ExternalId = externalId,
@@ -510,6 +517,163 @@ public class DeezerMetadataService : IMusicMetadataService
         };
     }
 
+    public async Task<List<ExternalPlaylist>> SearchPlaylistsAsync(string query, int limit = 20)
+    {
+        try
+        {
+            var url = $"{BaseUrl}/search/playlist?q={Uri.EscapeDataString(query)}&limit={limit}";
+            var response = await _httpClient.GetAsync(url);
+            
+            if (!response.IsSuccessStatusCode) return new List<ExternalPlaylist>();
+            
+            var json = await response.Content.ReadAsStringAsync();
+            var result = JsonDocument.Parse(json);
+            
+            var playlists = new List<ExternalPlaylist>();
+            if (result.RootElement.TryGetProperty("data", out var data))
+            {
+                foreach (var playlist in data.EnumerateArray())
+                {
+                    playlists.Add(ParseDeezerPlaylist(playlist));
+                }
+            }
+            
+            return playlists;
+        }
+        catch
+        {
+            return new List<ExternalPlaylist>();
+        }
+    }
+    
+    public async Task<ExternalPlaylist?> GetPlaylistAsync(string externalProvider, string externalId)
+    {
+        if (externalProvider != "deezer") return null;
+        
+        try
+        {
+            var url = $"{BaseUrl}/playlist/{externalId}";
+            var response = await _httpClient.GetAsync(url);
+            
+            if (!response.IsSuccessStatusCode) return null;
+            
+            var json = await response.Content.ReadAsStringAsync();
+            var playlistElement = JsonDocument.Parse(json).RootElement;
+            
+            if (playlistElement.TryGetProperty("error", out _)) return null;
+            
+            return ParseDeezerPlaylist(playlistElement);
+        }
+        catch
+        {
+            return null;
+        }
+    }
+    
+    public async Task<List<Song>> GetPlaylistTracksAsync(string externalProvider, string externalId)
+    {
+        if (externalProvider != "deezer") return new List<Song>();
+        
+        try
+        {
+            var url = $"{BaseUrl}/playlist/{externalId}";
+            var response = await _httpClient.GetAsync(url);
+            
+            if (!response.IsSuccessStatusCode) return new List<Song>();
+            
+            var json = await response.Content.ReadAsStringAsync();
+            var playlistElement = JsonDocument.Parse(json).RootElement;
+            
+            if (playlistElement.TryGetProperty("error", out _)) return new List<Song>();
+            
+            var songs = new List<Song>();
+            
+            // Get playlist name for album field
+            var playlistName = playlistElement.TryGetProperty("title", out var titleEl)
+                ? titleEl.GetString() ?? "Unknown Playlist"
+                : "Unknown Playlist";
+            
+            if (playlistElement.TryGetProperty("tracks", out var tracks) &&
+                tracks.TryGetProperty("data", out var tracksData))
+            {
+                int trackIndex = 1;
+                foreach (var track in tracksData.EnumerateArray())
+                {
+                    // For playlists, use the track's own artist (not a single album artist)
+                    var song = ParseDeezerTrack(track, trackIndex);
+                    
+                    // Override album name to be the playlist name
+                    song.Album = playlistName;
+                    
+                    if (ShouldIncludeSong(song))
+                    {
+                        songs.Add(song);
+                    }
+                    trackIndex++;
+                }
+            }
+            
+            return songs;
+        }
+        catch
+        {
+            return new List<Song>();
+        }
+    }
+
+    private ExternalPlaylist ParseDeezerPlaylist(JsonElement playlist)
+    {
+        var externalId = playlist.GetProperty("id").GetInt64().ToString();
+        
+        // Get curator/creator name
+        string? curatorName = null;
+        if (playlist.TryGetProperty("user", out var user) &&
+            user.TryGetProperty("name", out var userName))
+        {
+            curatorName = userName.GetString();
+        }
+        else if (playlist.TryGetProperty("creator", out var creator) &&
+                 creator.TryGetProperty("name", out var creatorName))
+        {
+            curatorName = creatorName.GetString();
+        }
+        
+        // Get creation date
+        DateTime? createdDate = null;
+        if (playlist.TryGetProperty("creation_date", out var creationDateEl))
+        {
+            var dateStr = creationDateEl.GetString();
+            if (!string.IsNullOrEmpty(dateStr) && DateTime.TryParse(dateStr, out var date))
+            {
+                createdDate = date;
+            }
+        }
+        
+        return new ExternalPlaylist
+        {
+            Id = Common.PlaylistIdHelper.CreatePlaylistId("deezer", externalId),
+            Name = playlist.GetProperty("title").GetString() ?? "",
+            Description = playlist.TryGetProperty("description", out var desc) 
+                ? desc.GetString() 
+                : null,
+            CuratorName = curatorName,
+            Provider = "deezer",
+            ExternalId = externalId,
+            TrackCount = playlist.TryGetProperty("nb_tracks", out var nbTracks) 
+                ? nbTracks.GetInt32() 
+                : 0,
+            Duration = playlist.TryGetProperty("duration", out var duration) 
+                ? duration.GetInt32() 
+                : 0,
+            CoverUrl = playlist.TryGetProperty("picture_medium", out var picture) 
+                ? picture.GetString() 
+                : (playlist.TryGetProperty("picture_big", out var pictureBig) 
+                    ? pictureBig.GetString() 
+                    : null),
+            CreatedDate = createdDate
+        };
+    }
+
     /// <summary>
     /// Determines whether a song should be included based on the explicit content filter setting
     /// </summary>

octo-fiesta/Services/IDownloadService.cs

@@ -42,6 +42,14 @@ public interface IDownloadService
     /// </summary>
     DownloadInfo? GetDownloadStatus(string songId);
     
+    /// <summary>
+    /// Gets the local path for a song if it has been downloaded already
+    /// </summary>
+    /// <param name="externalProvider">The provider (deezer, qobuz, etc.)</param>
+    /// <param name="externalId">The ID on the external provider</param>
+    /// <returns>The local file path if exists, null otherwise</returns>
+    Task<string?> GetLocalPathIfExistsAsync(string externalProvider, string externalId);
+    
     /// <summary>
     /// Checks if the service is properly configured and functional
     /// </summary>

octo-fiesta/Services/IMusicMetadataService.cs

@@ -54,4 +54,28 @@ public interface IMusicMetadataService
     /// Gets an artist's albums
     /// </summary>
     Task<List<Album>> GetArtistAlbumsAsync(string externalProvider, string externalId);
+    
+    /// <summary>
+    /// Searches for playlists on external providers
+    /// </summary>
+    /// <param name="query">Search term</param>
+    /// <param name="limit">Maximum number of results</param>
+    /// <returns>List of found playlists</returns>
+    Task<List<ExternalPlaylist>> SearchPlaylistsAsync(string query, int limit = 20);
+    
+    /// <summary>
+    /// Gets details of an external playlist (metadata only, not tracks)
+    /// </summary>
+    /// <param name="externalProvider">Provider name (e.g., "deezer", "qobuz")</param>
+    /// <param name="externalId">Playlist ID from the provider</param>
+    /// <returns>Playlist details or null if not found</returns>
+    Task<ExternalPlaylist?> GetPlaylistAsync(string externalProvider, string externalId);
+    
+    /// <summary>
+    /// Gets all tracks from an external playlist
+    /// </summary>
+    /// <param name="externalProvider">Provider name (e.g., "deezer", "qobuz")</param>
+    /// <param name="externalId">Playlist ID from the provider</param>
+    /// <returns>List of songs in the playlist</returns>
+    Task<List<Song>> GetPlaylistTracksAsync(string externalProvider, string externalId);
 }

octo-fiesta/Services/Qobuz/QobuzBundleService.cs

@@ -40,7 +40,7 @@ public class QobuzBundleService
     /// <summary>
     /// Gets the Qobuz App ID, extracting it from the bundle if not cached
     /// </summary>
-    public async Task<string> GetAppIdAsync()
+    public virtual async Task<string> GetAppIdAsync()
     {
         await EnsureInitializedAsync();
         return _cachedAppId!;
@@ -49,7 +49,7 @@ public class QobuzBundleService
     /// <summary>
     /// Gets the Qobuz secrets list, extracting them from the bundle if not cached
     /// </summary>
-    public async Task<List<string>> GetSecretsAsync()
+    public virtual async Task<List<string>> GetSecretsAsync()
     {
         await EnsureInitializedAsync();
         return _cachedSecrets!;
@@ -58,7 +58,7 @@ public class QobuzBundleService
     /// <summary>
     /// Gets a specific secret by index (used for signing requests)
     /// </summary>
-    public async Task<string> GetSecretAsync(int index = 0)
+    public virtual async Task<string> GetSecretAsync(int index = 0)
     {
         var secrets = await GetSecretsAsync();
         if (index < 0 || index >= secrets.Count)

octo-fiesta/Services/Qobuz/QobuzDownloadService.cs

@@ -8,6 +8,7 @@ using octo_fiesta.Models.Search;
 using octo_fiesta.Models.Subsonic;
 using octo_fiesta.Services.Local;
 using octo_fiesta.Services.Common;
+using octo_fiesta.Services.Subsonic;
 using Microsoft.Extensions.Options;
 using IOFile = System.IO.File;
 
@@ -43,8 +44,9 @@ public class QobuzDownloadService : BaseDownloadService
         QobuzBundleService bundleService,
         IOptions<SubsonicSettings> subsonicSettings,
         IOptions<QobuzSettings> qobuzSettings,
+        IServiceProvider serviceProvider,
         ILogger<QobuzDownloadService> logger)
-        : base(configuration, localLibraryService, metadataService, subsonicSettings.Value, logger)
+        : base(configuration, localLibraryService, metadataService, subsonicSettings.Value, serviceProvider, logger)
     {
         _httpClient = httpClientFactory.CreateClient();
         _bundleService = bundleService;
@@ -108,7 +110,8 @@ public class QobuzDownloadService : BaseDownloadService
 
         // Build organized folder structure using AlbumArtist (fallback to Artist for singles)
         var artistForPath = song.AlbumArtist ?? song.Artist;
-        var outputPath = PathHelper.BuildTrackPath(DownloadPath, artistForPath, song.Album, song.Title, song.Track, extension);
+        var basePath = SubsonicSettings.StorageMode == StorageMode.Cache ? CachePath : DownloadPath;
+        var outputPath = PathHelper.BuildTrackPath(basePath, artistForPath, song.Album, song.Title, song.Track, extension);
         
         var albumFolder = Path.GetDirectoryName(outputPath)!;
         EnsureDirectoryExists(albumFolder);

octo-fiesta/Services/Qobuz/QobuzMetadataService.cs

@@ -212,6 +212,12 @@ public class QobuzMetadataService : IMusicMetadataService
                 foreach (var track in tracksData.EnumerateArray())
                 {
                     var song = ParseQobuzTrack(track);
+                    
+                    // Ensure album metadata is set (tracks in album response may not have full album object)
+                    song.Album = album.Title;
+                    song.AlbumId = album.Id;
+                    song.AlbumArtist = album.Artist;
+                    
                     if (ShouldIncludeSong(song))
                     {
                         album.Songs.Add(song);
@@ -305,6 +311,180 @@ public class QobuzMetadataService : IMusicMetadataService
         }
     }
 
+    public async Task<List<ExternalPlaylist>> SearchPlaylistsAsync(string query, int limit = 20)
+    {
+        try
+        {
+            var appId = await _bundleService.GetAppIdAsync();
+            var url = $"{BaseUrl}playlist/search?query={Uri.EscapeDataString(query)}&limit={limit}&app_id={appId}";
+            
+            var response = await GetWithAuthAsync(url);
+            if (!response.IsSuccessStatusCode) return new List<ExternalPlaylist>();
+            
+            var json = await response.Content.ReadAsStringAsync();
+            var result = JsonDocument.Parse(json);
+            
+            var playlists = new List<ExternalPlaylist>();
+            if (result.RootElement.TryGetProperty("playlists", out var playlistsData) &&
+                playlistsData.TryGetProperty("items", out var items))
+            {
+                foreach (var playlist in items.EnumerateArray())
+                {
+                    playlists.Add(ParseQobuzPlaylist(playlist));
+                }
+            }
+            
+            return playlists;
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to search playlists for query: {Query}", query);
+            return new List<ExternalPlaylist>();
+        }
+    }
+    
+    public async Task<ExternalPlaylist?> GetPlaylistAsync(string externalProvider, string externalId)
+    {
+        if (externalProvider != "qobuz") return null;
+        
+        try
+        {
+            var appId = await _bundleService.GetAppIdAsync();
+            var url = $"{BaseUrl}playlist/get?playlist_id={externalId}&app_id={appId}";
+            
+            var response = await GetWithAuthAsync(url);
+            if (!response.IsSuccessStatusCode) return null;
+            
+            var json = await response.Content.ReadAsStringAsync();
+            var playlistElement = JsonDocument.Parse(json).RootElement;
+            
+            if (playlistElement.TryGetProperty("error", out _)) return null;
+            
+            return ParseQobuzPlaylist(playlistElement);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to get playlist {ExternalId}", externalId);
+            return null;
+        }
+    }
+    
+    public async Task<List<Song>> GetPlaylistTracksAsync(string externalProvider, string externalId)
+    {
+        if (externalProvider != "qobuz") return new List<Song>();
+        
+        try
+        {
+            var appId = await _bundleService.GetAppIdAsync();
+            var url = $"{BaseUrl}playlist/get?playlist_id={externalId}&app_id={appId}&extra=tracks";
+            
+            var response = await GetWithAuthAsync(url);
+            if (!response.IsSuccessStatusCode) return new List<Song>();
+            
+            var json = await response.Content.ReadAsStringAsync();
+            var playlistElement = JsonDocument.Parse(json).RootElement;
+            
+            if (playlistElement.TryGetProperty("error", out _)) return new List<Song>();
+            
+            var songs = new List<Song>();
+            
+            // Get playlist name for album field
+            var playlistName = playlistElement.TryGetProperty("name", out var nameEl)
+                ? nameEl.GetString() ?? "Unknown Playlist"
+                : "Unknown Playlist";
+            
+            if (playlistElement.TryGetProperty("tracks", out var tracks) &&
+                tracks.TryGetProperty("items", out var tracksData))
+            {
+                int trackIndex = 1;
+                foreach (var track in tracksData.EnumerateArray())
+                {
+                    // For playlists, use the track's own artist (not a single album artist)
+                    var song = ParseQobuzTrack(track);
+                    
+                    // Override album name to be the playlist name
+                    song.Album = playlistName;
+                    song.Track = trackIndex;
+                    
+                    if (ShouldIncludeSong(song))
+                    {
+                        songs.Add(song);
+                    }
+                    trackIndex++;
+                }
+            }
+            
+            return songs;
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to get playlist tracks for {ExternalId}", externalId);
+            return new List<Song>();
+        }
+    }
+    
+    private ExternalPlaylist ParseQobuzPlaylist(JsonElement playlist)
+    {
+        var externalId = GetIdAsString(playlist.GetProperty("id"));
+        
+        // Get curator/creator name
+        string? curatorName = null;
+        if (playlist.TryGetProperty("owner", out var owner) &&
+            owner.TryGetProperty("name", out var ownerName))
+        {
+            curatorName = ownerName.GetString();
+        }
+        
+        // Get creation date
+        DateTime? createdDate = null;
+        if (playlist.TryGetProperty("created_at", out var createdAtEl))
+        {
+            var timestamp = createdAtEl.GetInt64();
+            createdDate = DateTimeOffset.FromUnixTimeSeconds(timestamp).DateTime;
+        }
+        
+        // Get cover URL from images
+        string? coverUrl = null;
+        if (playlist.TryGetProperty("images300", out var images300))
+        {
+            var imagesArray = images300.EnumerateArray().ToList();
+            if (imagesArray.Count > 0)
+            {
+                coverUrl = imagesArray[0].GetString();
+            }
+        }
+        else if (playlist.TryGetProperty("image_rectangle", out var imageRect))
+        {
+            var imagesArray = imageRect.EnumerateArray().ToList();
+            if (imagesArray.Count > 0)
+            {
+                coverUrl = imagesArray[0].GetString();
+            }
+        }
+        
+        return new ExternalPlaylist
+        {
+            Id = Common.PlaylistIdHelper.CreatePlaylistId("qobuz", externalId),
+            Name = playlist.TryGetProperty("name", out var name)
+                ? name.GetString() ?? ""
+                : "",
+            Description = playlist.TryGetProperty("description", out var desc)
+                ? desc.GetString()
+                : null,
+            CuratorName = curatorName,
+            Provider = "qobuz",
+            ExternalId = externalId,
+            TrackCount = playlist.TryGetProperty("tracks_count", out var tracksCount)
+                ? tracksCount.GetInt32()
+                : 0,
+            Duration = playlist.TryGetProperty("duration", out var duration)
+                ? duration.GetInt32()
+                : 0,
+            CoverUrl = coverUrl,
+            CreatedDate = createdDate
+        };
+    }
+
     /// <summary>
     /// Safely gets an ID value as a string, handling both number and string types from JSON
     /// </summary>

octo-fiesta/Services/Subsonic/PlaylistSyncService.cs

@@ -0,0 +1,411 @@
+using System.Collections.Concurrent;
+using System.Text;
+using Microsoft.Extensions.Options;
+using octo_fiesta.Models.Domain;
+using octo_fiesta.Models.Settings;
+using octo_fiesta.Models.Subsonic;
+using octo_fiesta.Services.Common;
+using IOFile = System.IO.File;
+
+namespace octo_fiesta.Services.Subsonic;
+
+/// <summary>
+/// Service responsible for downloading playlist tracks and creating M3U files
+/// </summary>
+public class PlaylistSyncService
+{
+    private readonly IMusicMetadataService _deezerMetadataService;
+    private readonly IMusicMetadataService _qobuzMetadataService;
+    private readonly IEnumerable<IDownloadService> _downloadServices;
+    private readonly IConfiguration _configuration;
+    private readonly SubsonicSettings _subsonicSettings;
+    private readonly ILogger<PlaylistSyncService> _logger;
+    
+    // In-memory cache to track which playlist a track belongs to
+    // Key: trackId (format: ext-{provider}-{externalId}), Value: playlistId
+    // TTL: 5 minutes (tracks expire automatically)
+    private readonly ConcurrentDictionary<string, (string PlaylistId, DateTime ExpiresAt)> _trackPlaylistCache = new();
+    private static readonly TimeSpan CacheTTL = TimeSpan.FromMinutes(5);
+    
+    private readonly string _musicDirectory;
+    private readonly string _playlistDirectory;
+    
+    // Cancellation token for background cleanup task
+    private readonly CancellationTokenSource _cleanupCancellationTokenSource = new();
+    private readonly Task _cleanupTask;
+    
+    public PlaylistSyncService(
+        IEnumerable<IMusicMetadataService> metadataServices,
+        IEnumerable<IDownloadService> downloadServices,
+        IConfiguration configuration,
+        IOptions<SubsonicSettings> subsonicSettings,
+        ILogger<PlaylistSyncService> logger)
+    {
+        // Get Deezer and Qobuz metadata services
+        _deezerMetadataService = metadataServices.FirstOrDefault(s => s.GetType().Name.Contains("Deezer"))
+            ?? throw new InvalidOperationException("Deezer metadata service not found");
+        _qobuzMetadataService = metadataServices.FirstOrDefault(s => s.GetType().Name.Contains("Qobuz"))
+            ?? throw new InvalidOperationException("Qobuz metadata service not found");
+        
+        _downloadServices = downloadServices;
+        _configuration = configuration;
+        _subsonicSettings = subsonicSettings.Value;
+        _logger = logger;
+        
+        _musicDirectory = configuration["Library:DownloadPath"] ?? "./downloads";
+        _playlistDirectory = Path.Combine(_musicDirectory, _subsonicSettings.PlaylistsDirectory ?? "playlists");
+        
+        // Ensure playlists directory exists
+        if (!Directory.Exists(_playlistDirectory))
+        {
+            Directory.CreateDirectory(_playlistDirectory);
+        }
+        
+        // Start background cleanup task for expired cache entries
+        _cleanupTask = Task.Run(() => CleanupExpiredCacheEntriesAsync(_cleanupCancellationTokenSource.Token));
+    }
+    
+    /// <summary>
+    /// Gets the metadata service for the specified provider
+    /// </summary>
+    private IMusicMetadataService? GetMetadataServiceForProvider(string provider)
+    {
+        return provider.ToLower() switch
+        {
+            "deezer" => _deezerMetadataService,
+            "qobuz" => _qobuzMetadataService,
+            _ => null
+        };
+    }
+    
+    /// <summary>
+    /// Adds a track to the playlist context cache.
+    /// This allows the download service to know which playlist a track belongs to.
+    /// </summary>
+    public void AddTrackToPlaylistCache(string trackId, string playlistId)
+    {
+        var expiresAt = DateTime.UtcNow.Add(CacheTTL);
+        _trackPlaylistCache[trackId] = (playlistId, expiresAt);
+        _logger.LogInformation("Added track {TrackId} to playlist cache with playlistId {PlaylistId}", trackId, playlistId);
+    }
+    
+    /// <summary>
+    /// Gets the playlist ID for a given track ID from cache.
+    /// Returns null if not found or expired.
+    /// </summary>
+    public string? GetPlaylistIdForTrack(string trackId)
+    {
+        if (_trackPlaylistCache.TryGetValue(trackId, out var entry))
+        {
+            if (entry.ExpiresAt > DateTime.UtcNow)
+            {
+                return entry.PlaylistId;
+            }
+            
+            // Expired, remove it
+            _trackPlaylistCache.TryRemove(trackId, out _);
+        }
+        
+        return null;
+    }
+    
+    /// <summary>
+    /// Downloads all tracks from a playlist and creates an M3U file.
+    /// This is triggered when a user stars a playlist.
+    /// </summary>
+    public async Task DownloadFullPlaylistAsync(string playlistId, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            _logger.LogInformation("Starting download for playlist {PlaylistId}", playlistId);
+            
+            // Parse playlist ID
+            if (!PlaylistIdHelper.IsExternalPlaylist(playlistId))
+            {
+                _logger.LogWarning("Invalid playlist ID format: {PlaylistId}", playlistId);
+                return;
+            }
+            
+            var (provider, externalId) = PlaylistIdHelper.ParsePlaylistId(playlistId);
+            
+            // Get playlist metadata
+            var metadataService = GetMetadataServiceForProvider(provider);
+            if (metadataService == null)
+            {
+                throw new NotSupportedException($"Provider '{provider}' not supported for playlists");
+            }
+            
+            var playlist = await metadataService.GetPlaylistAsync(provider, externalId);
+            if (playlist == null)
+            {
+                _logger.LogWarning("Playlist not found: {PlaylistId}", playlistId);
+                return;
+            }
+            
+            var tracks = await metadataService.GetPlaylistTracksAsync(provider, externalId);
+            if (tracks == null || tracks.Count == 0)
+            {
+                _logger.LogWarning("No tracks found in playlist {PlaylistId}", playlistId);
+                return;
+            }
+            
+            _logger.LogInformation("Found {TrackCount} tracks in playlist '{PlaylistName}'", tracks.Count, playlist.Name);
+            
+            // Get the appropriate download service for this provider
+            var downloadService = _downloadServices.FirstOrDefault(s => 
+                s.GetType().Name.Contains(provider, StringComparison.OrdinalIgnoreCase));
+            
+            if (downloadService == null)
+            {
+                _logger.LogError("No download service found for provider '{Provider}'", provider);
+                return;
+            }
+            
+            // Download all tracks (M3U will be created once at the end)
+            var downloadedTracks = new List<(Song Song, string LocalPath)>();
+            
+            foreach (var track in tracks)
+            {
+                try
+                {
+                    if (string.IsNullOrEmpty(track.ExternalId))
+                    {
+                        _logger.LogWarning("Track has no external ID, skipping: {Title}", track.Title);
+                        continue;
+                    }
+                    
+                    // Add track to playlist cache BEFORE downloading
+                    // This marks it as part of a full playlist download, so AddTrackToM3UAsync will skip real-time updates
+                    var trackId = $"ext-{provider}-{track.ExternalId}";
+                    AddTrackToPlaylistCache(trackId, playlistId);
+                    
+                    _logger.LogInformation("Downloading track '{Artist} - {Title}'", track.Artist, track.Title);
+                    var localPath = await downloadService.DownloadSongAsync(provider, track.ExternalId, cancellationToken);
+                    
+                    downloadedTracks.Add((track, localPath));
+                    _logger.LogDebug("Downloaded: {Path}", localPath);
+                }
+                catch (Exception ex)
+                {
+                    _logger.LogWarning(ex, "Failed to download track '{Artist} - {Title}'", track.Artist, track.Title);
+                }
+            }
+            
+            if (downloadedTracks.Count == 0)
+            {
+                _logger.LogWarning("No tracks were successfully downloaded for playlist '{PlaylistName}'", playlist.Name);
+                return;
+            }
+            
+            // Create M3U file ONCE at the end with all downloaded tracks
+            await CreateM3UPlaylistAsync(playlist.Name, downloadedTracks);
+            
+            _logger.LogInformation("Playlist download completed: {DownloadedCount}/{TotalCount} tracks for '{PlaylistName}'",
+                downloadedTracks.Count, tracks.Count, playlist.Name);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to download playlist {PlaylistId}", playlistId);
+            throw;
+        }
+    }
+    
+    /// <summary>
+    /// Creates an M3U playlist file with relative paths to downloaded tracks
+    /// </summary>
+    private async Task CreateM3UPlaylistAsync(string playlistName, List<(Song Song, string LocalPath)> tracks)
+    {
+        try
+        {
+            // Sanitize playlist name for file system
+            var fileName = PathHelper.SanitizeFileName(playlistName) + ".m3u";
+            var playlistPath = Path.Combine(_playlistDirectory, fileName);
+            
+            var m3uContent = new StringBuilder();
+            m3uContent.AppendLine("#EXTM3U");
+            
+            foreach (var (song, localPath) in tracks)
+            {
+                // Calculate relative path from playlist directory to track
+                var relativePath = Path.GetRelativePath(_playlistDirectory, localPath);
+                
+                // Convert backslashes to forward slashes for M3U compatibility
+                relativePath = relativePath.Replace('\\', '/');
+                
+                // Add EXTINF line with duration and artist - title
+                var duration = song.Duration ?? 0;
+                m3uContent.AppendLine($"#EXTINF:{duration},{song.Artist} - {song.Title}");
+                m3uContent.AppendLine(relativePath);
+            }
+            
+            await IOFile.WriteAllTextAsync(playlistPath, m3uContent.ToString());
+            _logger.LogInformation("Created M3U playlist: {Path}", playlistPath);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to create M3U playlist for '{PlaylistName}'", playlistName);
+            throw;
+        }
+    }
+    
+    /// <summary>
+    /// Adds a track to an existing M3U playlist or creates it if it doesn't exist.
+    /// Called when individual tracks are played/downloaded (NOT during full playlist download).
+    /// The M3U is rebuilt in the correct playlist order each time.
+    /// </summary>
+    /// <param name="isFullPlaylistDownload">If true, skips M3U update (will be done at the end by DownloadFullPlaylistAsync)</param>
+    public async Task AddTrackToM3UAsync(string playlistId, Song track, string localPath, bool isFullPlaylistDownload = false)
+    {
+        // Skip real-time updates during full playlist download (M3U will be created once at the end)
+        if (isFullPlaylistDownload)
+        {
+            _logger.LogDebug("Skipping M3U update for track {TrackId} (full playlist download in progress)", track.Id);
+            return;
+        }
+        
+        try
+        {
+            // Get playlist metadata to get the name and track order
+            if (!PlaylistIdHelper.IsExternalPlaylist(playlistId))
+            {
+                _logger.LogWarning("Invalid playlist ID format: {PlaylistId}", playlistId);
+                return;
+            }
+            
+            var (provider, externalId) = PlaylistIdHelper.ParsePlaylistId(playlistId);
+            
+            var metadataService = GetMetadataServiceForProvider(provider);
+            if (metadataService == null)
+            {
+                _logger.LogWarning("No metadata service found for provider '{Provider}'", provider);
+                return;
+            }
+            
+            var playlist = await metadataService.GetPlaylistAsync(provider, externalId);
+            if (playlist == null)
+            {
+                _logger.LogWarning("Playlist not found: {PlaylistId}", playlistId);
+                return;
+            }
+            
+            // Get all tracks from the playlist to maintain order
+            var allPlaylistTracks = await metadataService.GetPlaylistTracksAsync(provider, externalId);
+            if (allPlaylistTracks == null || allPlaylistTracks.Count == 0)
+            {
+                _logger.LogWarning("No tracks found in playlist: {PlaylistId}", playlistId);
+                return;
+            }
+            
+            // Sanitize playlist name for file system
+            var fileName = PathHelper.SanitizeFileName(playlist.Name) + ".m3u";
+            var playlistPath = Path.Combine(_playlistDirectory, fileName);
+            
+            // Build M3U content in the correct order
+            var m3uContent = new StringBuilder();
+            m3uContent.AppendLine("#EXTM3U");
+            
+            int addedCount = 0;
+            foreach (var playlistTrack in allPlaylistTracks)
+            {
+                // Check if this track has been downloaded locally
+                string? trackLocalPath = null;
+                
+                // If this is the track we just downloaded
+                if (playlistTrack.Id == track.Id)
+                {
+                    trackLocalPath = localPath;
+                }
+                else
+                {
+                    // Check if track was previously downloaded
+                    var trackProvider = playlistTrack.ExternalProvider;
+                    var trackExternalId = playlistTrack.ExternalId;
+                    
+                    if (!string.IsNullOrEmpty(trackProvider) && !string.IsNullOrEmpty(trackExternalId))
+                    {
+                        // Try to find the download service for this provider
+                        var downloadService = _downloadServices.FirstOrDefault(s => 
+                            s.GetType().Name.Contains(trackProvider, StringComparison.OrdinalIgnoreCase));
+                        
+                        if (downloadService != null)
+                        {
+                            trackLocalPath = await downloadService.GetLocalPathIfExistsAsync(trackProvider, trackExternalId);
+                        }
+                    }
+                }
+                
+                // If track is downloaded, add it to M3U
+                if (!string.IsNullOrEmpty(trackLocalPath) && IOFile.Exists(trackLocalPath))
+                {
+                    var relativePath = Path.GetRelativePath(_playlistDirectory, trackLocalPath);
+                    relativePath = relativePath.Replace('\\', '/');
+                    
+                    var duration = playlistTrack.Duration ?? 0;
+                    m3uContent.AppendLine($"#EXTINF:{duration},{playlistTrack.Artist} - {playlistTrack.Title}");
+                    m3uContent.AppendLine(relativePath);
+                    addedCount++;
+                }
+            }
+            
+            // Write the M3U file (overwrites existing)
+            await IOFile.WriteAllTextAsync(playlistPath, m3uContent.ToString());
+            _logger.LogInformation("Updated M3U playlist '{PlaylistName}' with {Count} tracks (in correct order)", 
+                playlist.Name, addedCount);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to add track to M3U playlist");
+        }
+    }
+    
+    /// <summary>
+    /// Background task to clean up expired cache entries every minute
+    /// </summary>
+    private async Task CleanupExpiredCacheEntriesAsync(CancellationToken cancellationToken)
+    {
+        while (!cancellationToken.IsCancellationRequested)
+        {
+            try
+            {
+                await Task.Delay(TimeSpan.FromMinutes(1), cancellationToken);
+                
+                var now = DateTime.UtcNow;
+                var expiredKeys = _trackPlaylistCache
+                    .Where(kvp => kvp.Value.ExpiresAt <= now)
+                    .Select(kvp => kvp.Key)
+                    .ToList();
+                
+                foreach (var key in expiredKeys)
+                {
+                    _trackPlaylistCache.TryRemove(key, out _);
+                }
+                
+                if (expiredKeys.Count > 0)
+                {
+                    _logger.LogDebug("Cleaned up {Count} expired playlist cache entries", expiredKeys.Count);
+                }
+            }
+            catch (OperationCanceledException)
+            {
+                // Expected when cancellation is requested
+                break;
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "Error during playlist cache cleanup");
+            }
+        }
+        
+        _logger.LogInformation("Playlist cache cleanup task stopped");
+    }
+    
+    /// <summary>
+    /// Stops the background cleanup task
+    /// </summary>
+    public async Task StopCleanupAsync()
+    {
+        _cleanupCancellationTokenSource.Cancel();
+        await _cleanupTask;
+        _cleanupCancellationTokenSource.Dispose();
+    }
+}

octo-fiesta/Services/Subsonic/SubsonicModelMapper.cs

@@ -2,6 +2,7 @@ using System.Text;
 using System.Text.Json;
 using System.Xml.Linq;
 using octo_fiesta.Models.Search;
+using octo_fiesta.Models.Subsonic;
 
 namespace octo_fiesta.Services.Subsonic;
 
@@ -97,22 +98,23 @@ public class SubsonicModelMapper
     }
 
     /// <summary>
-    /// Merges local search results with external search results, deduplicating by name.
+    /// Merges local and external search results (songs, albums, artists, playlists).
     /// </summary>
     public (List<object> MergedSongs, List<object> MergedAlbums, List<object> MergedArtists) MergeSearchResults(
         List<object> localSongs,
         List<object> localAlbums,
         List<object> localArtists,
         SearchResult externalResult,
+        List<ExternalPlaylist> externalPlaylists,
         bool isJson)
     {
         if (isJson)
         {
-            return MergeSearchResultsJson(localSongs, localAlbums, localArtists, externalResult);
+            return MergeSearchResultsJson(localSongs, localAlbums, localArtists, externalResult, externalPlaylists);
         }
         else
         {
-            return MergeSearchResultsXml(localSongs, localAlbums, localArtists, externalResult);
+            return MergeSearchResultsXml(localSongs, localAlbums, localArtists, externalResult, externalPlaylists);
         }
     }
 
@@ -120,14 +122,17 @@ public class SubsonicModelMapper
         List<object> localSongs,
         List<object> localAlbums,
         List<object> localArtists,
-        SearchResult externalResult)
+        SearchResult externalResult,
+        List<ExternalPlaylist> externalPlaylists)
     {
         var mergedSongs = localSongs
             .Concat(externalResult.Songs.Select(s => _responseBuilder.ConvertSongToJson(s)))
             .ToList();
         
+        // Merge albums with playlists (playlists appear as albums with genre "Playlist")
         var mergedAlbums = localAlbums
             .Concat(externalResult.Albums.Select(a => _responseBuilder.ConvertAlbumToJson(a)))
+            .Concat(externalPlaylists.Select(p => ConvertPlaylistToAlbumJson(p)))
             .ToList();
         
         // Deduplicate artists by name - prefer local artists over external ones
@@ -157,7 +162,8 @@ public class SubsonicModelMapper
         List<object> localSongs,
         List<object> localAlbums,
         List<object> localArtists,
-        SearchResult externalResult)
+        SearchResult externalResult,
+        List<ExternalPlaylist> externalPlaylists)
     {
         var ns = XNamespace.Get("http://subsonic.org/restapi");
         
@@ -196,6 +202,11 @@ public class SubsonicModelMapper
         {
             mergedAlbums.Add(_responseBuilder.ConvertAlbumToXml(album, ns));
         }
+        // Add playlists as albums
+        foreach (var playlist in externalPlaylists)
+        {
+            mergedAlbums.Add(ConvertPlaylistToAlbumXml(playlist, ns));
+        }
         
         // Songs
         var mergedSongs = new List<object>();
@@ -211,4 +222,81 @@ public class SubsonicModelMapper
 
         return (mergedSongs, mergedAlbums, mergedArtists);
     }
+    
+    /// <summary>
+    /// Converts an ExternalPlaylist to a JSON object representing an album.
+    /// Playlists are represented as albums with genre "Playlist" and artist "🎵 {Provider} {Curator}".
+    /// </summary>
+    private Dictionary<string, object> ConvertPlaylistToAlbumJson(ExternalPlaylist playlist)
+    {
+        var artistName = $"🎵 {char.ToUpper(playlist.Provider[0])}{playlist.Provider.Substring(1)}";
+        if (!string.IsNullOrEmpty(playlist.CuratorName))
+        {
+            artistName += $" {playlist.CuratorName}";
+        }
+        
+        var artistId = $"curator-{playlist.Provider}-{playlist.CuratorName?.ToLowerInvariant().Replace(" ", "-") ?? "unknown"}";
+        
+        var album = new Dictionary<string, object>
+        {
+            ["id"] = playlist.Id,
+            ["name"] = playlist.Name,
+            ["artist"] = artistName,
+            ["artistId"] = artistId,
+            ["genre"] = "Playlist",
+            ["songCount"] = playlist.TrackCount,
+            ["duration"] = playlist.Duration
+        };
+        
+        if (playlist.CreatedDate.HasValue)
+        {
+            album["year"] = playlist.CreatedDate.Value.Year;
+            album["created"] = playlist.CreatedDate.Value.ToString("yyyy-MM-ddTHH:mm:ss");
+        }
+        
+        if (!string.IsNullOrEmpty(playlist.CoverUrl))
+        {
+            album["coverArt"] = playlist.Id;
+        }
+        
+        return album;
+    }
+    
+    /// <summary>
+    /// Converts an ExternalPlaylist to an XML element representing an album.
+    /// Playlists are represented as albums with genre "Playlist" and artist "🎵 {Provider} {Curator}".
+    /// </summary>
+    private XElement ConvertPlaylistToAlbumXml(ExternalPlaylist playlist, XNamespace ns)
+    {
+        var artistName = $"🎵 {char.ToUpper(playlist.Provider[0])}{playlist.Provider.Substring(1)}";
+        if (!string.IsNullOrEmpty(playlist.CuratorName))
+        {
+            artistName += $" {playlist.CuratorName}";
+        }
+        
+        var artistId = $"curator-{playlist.Provider}-{playlist.CuratorName?.ToLowerInvariant().Replace(" ", "-") ?? "unknown"}";
+        
+        var album = new XElement(ns + "album",
+            new XAttribute("id", playlist.Id),
+            new XAttribute("name", playlist.Name),
+            new XAttribute("artist", artistName),
+            new XAttribute("artistId", artistId),
+            new XAttribute("genre", "Playlist"),
+            new XAttribute("songCount", playlist.TrackCount),
+            new XAttribute("duration", playlist.Duration)
+        );
+        
+        if (playlist.CreatedDate.HasValue)
+        {
+            album.Add(new XAttribute("year", playlist.CreatedDate.Value.Year));
+            album.Add(new XAttribute("created", playlist.CreatedDate.Value.ToString("yyyy-MM-ddTHH:mm:ss")));
+        }
+        
+        if (!string.IsNullOrEmpty(playlist.CoverUrl))
+        {
+            album.Add(new XAttribute("coverArt", playlist.Id));
+        }
+        
+        return album;
+    }
 }

octo-fiesta/Services/Subsonic/SubsonicResponseBuilder.cs

@@ -2,6 +2,7 @@ using Microsoft.AspNetCore.Mvc;
 using System.Xml.Linq;
 using System.Text.Json;
 using octo_fiesta.Models.Domain;
+using octo_fiesta.Models.Subsonic;
 
 namespace octo_fiesta.Services.Subsonic;
 
@@ -137,6 +138,81 @@ public class SubsonicResponseBuilder
         );
         return new ContentResult { Content = doc.ToString(), ContentType = "application/xml" };
     }
+    
+    /// <summary>
+    /// Creates a Subsonic response for a playlist represented as an album.
+    /// Playlists appear as albums with genre "Playlist".
+    /// </summary>
+    public IActionResult CreatePlaylistAsAlbumResponse(string format, ExternalPlaylist playlist, List<Song> tracks)
+    {
+        var totalDuration = tracks.Sum(s => s.Duration ?? 0);
+        
+        // Build artist name with emoji and curator
+        var artistName = $"🎵 {char.ToUpper(playlist.Provider[0])}{playlist.Provider.Substring(1)}";
+        if (!string.IsNullOrEmpty(playlist.CuratorName))
+        {
+            artistName += $" {playlist.CuratorName}";
+        }
+        
+        var artistId = $"curator-{playlist.Provider}-{playlist.CuratorName?.ToLowerInvariant().Replace(" ", "-") ?? "unknown"}";
+        
+        if (format == "json")
+        {
+            return CreateJsonResponse(new 
+            { 
+                status = "ok", 
+                version = SubsonicVersion,
+                album = new
+                {
+                    id = playlist.Id,
+                    name = playlist.Name,
+                    artist = artistName,
+                    artistId = artistId,
+                    coverArt = playlist.Id,
+                    songCount = tracks.Count,
+                    duration = totalDuration,
+                    year = playlist.CreatedDate?.Year ?? 0,
+                    genre = "Playlist",
+                    isCompilation = false,
+                    created = playlist.CreatedDate?.ToString("yyyy-MM-ddTHH:mm:ss"),
+                    song = tracks.Select(s => ConvertSongToJson(s)).ToList()
+                }
+            });
+        }
+        
+        var ns = XNamespace.Get(SubsonicNamespace);
+        var albumElement = new XElement(ns + "album",
+            new XAttribute("id", playlist.Id),
+            new XAttribute("name", playlist.Name),
+            new XAttribute("artist", artistName),
+            new XAttribute("artistId", artistId),
+            new XAttribute("songCount", tracks.Count),
+            new XAttribute("duration", totalDuration),
+            new XAttribute("genre", "Playlist"),
+            new XAttribute("coverArt", playlist.Id)
+        );
+        
+        if (playlist.CreatedDate.HasValue)
+        {
+            albumElement.Add(new XAttribute("year", playlist.CreatedDate.Value.Year));
+            albumElement.Add(new XAttribute("created", playlist.CreatedDate.Value.ToString("yyyy-MM-ddTHH:mm:ss")));
+        }
+        
+        // Add songs
+        foreach (var song in tracks)
+        {
+            albumElement.Add(ConvertSongToXml(song, ns));
+        }
+        
+        var doc = new XDocument(
+            new XElement(ns + "subsonic-response",
+                new XAttribute("status", "ok"),
+                new XAttribute("version", SubsonicVersion),
+                albumElement
+            )
+        );
+        return new ContentResult { Content = doc.ToString(), ContentType = "application/xml" };
+    }
 
     /// <summary>
     /// Creates a Subsonic response containing an artist with albums.