Add parallel provider racing for searches and lyrics pre-fetching

- Created ParallelMetadataService to race all providers and return fastest result
- Search now uses parallel service when available for lower latency
- Pre-fetch LRCLib lyrics for top 3 search results in background
- FuzzyMatcher already handles apostrophe normalization (applied everywhere)

allstarr/Controllers/JellyfinController.cs

@@ -29,6 +29,7 @@ public class JellyfinController : ControllerBase
     private readonly SpotifyImportSettings _spotifySettings;
     private readonly SpotifyApiSettings _spotifyApiSettings;
     private readonly IMusicMetadataService _metadataService;
+    private readonly ParallelMetadataService? _parallelMetadataService;
     private readonly ILocalLibraryService _localLibraryService;
     private readonly IDownloadService _downloadService;
     private readonly JellyfinResponseBuilder _responseBuilder;
@@ -38,6 +39,7 @@ public class JellyfinController : ControllerBase
     private readonly PlaylistSyncService? _playlistSyncService;
     private readonly SpotifyPlaylistFetcher? _spotifyPlaylistFetcher;
     private readonly SpotifyLyricsService? _spotifyLyricsService;
+    private readonly LrclibService? _lrclibService;
     private readonly RedisCacheService _cache;
     private readonly ILogger<JellyfinController> _logger;
 
@@ -54,14 +56,17 @@ public class JellyfinController : ControllerBase
         JellyfinSessionManager sessionManager,
         RedisCacheService cache,
         ILogger<JellyfinController> logger,
+        ParallelMetadataService? parallelMetadataService = null,
         PlaylistSyncService? playlistSyncService = null,
         SpotifyPlaylistFetcher? spotifyPlaylistFetcher = null,
-        SpotifyLyricsService? spotifyLyricsService = null)
+        SpotifyLyricsService? spotifyLyricsService = null,
+        LrclibService? lrclibService = null)
     {
         _settings = settings.Value;
         _spotifySettings = spotifySettings.Value;
         _spotifyApiSettings = spotifyApiSettings.Value;
         _metadataService = metadataService;
+        _parallelMetadataService = parallelMetadataService;
         _localLibraryService = localLibraryService;
         _downloadService = downloadService;
         _responseBuilder = responseBuilder;
@@ -71,6 +76,7 @@ public class JellyfinController : ControllerBase
         _playlistSyncService = playlistSyncService;
         _spotifyPlaylistFetcher = spotifyPlaylistFetcher;
         _spotifyLyricsService = spotifyLyricsService;
+        _lrclibService = lrclibService;
         _cache = cache;
         _logger = logger;
 
@@ -241,7 +247,11 @@ public class JellyfinController : ControllerBase
         // Run local and external searches in parallel
         var itemTypes = ParseItemTypes(includeItemTypes);
         var jellyfinTask = _proxyService.SearchAsync(cleanQuery, itemTypes, limit, recursive, Request.Headers);
-        var externalTask = _metadataService.SearchAllAsync(cleanQuery, limit, limit, limit);
+        
+        // Use parallel metadata service if available (races providers), otherwise use primary
+        var externalTask = _parallelMetadataService != null
+            ? _parallelMetadataService.SearchAllAsync(cleanQuery, limit, limit, limit)
+            : _metadataService.SearchAllAsync(cleanQuery, limit, limit, limit);
 
         var playlistTask = _settings.EnableExternalPlaylists
             ? _metadataService.SearchPlaylistsAsync(cleanQuery, limit)
@@ -312,6 +322,39 @@ public class JellyfinController : ControllerBase
         _logger.LogInformation("Scored and filtered results: Songs={Songs}, Albums={Albums}, Artists={Artists}",
             mergedSongs.Count, mergedAlbums.Count, mergedArtists.Count);
 
+        // Pre-fetch lyrics for top 3 songs in background (don't await)
+        if (_lrclibService != null && mergedSongs.Count > 0)
+        {
+            _ = Task.Run(async () =>
+            {
+                try
+                {
+                    var top3 = mergedSongs.Take(3).ToList();
+                    _logger.LogDebug("🎵 Pre-fetching lyrics for top {Count} search results", top3.Count);
+                    
+                    foreach (var songItem in top3)
+                    {
+                        if (songItem.TryGetValue("Name", out var nameObj) && nameObj is JsonElement nameEl &&
+                            songItem.TryGetValue("Artists", out var artistsObj) && artistsObj is JsonElement artistsEl &&
+                            artistsEl.GetArrayLength() > 0)
+                        {
+                            var title = nameEl.GetString() ?? "";
+                            var artist = artistsEl[0].GetString() ?? "";
+                            
+                            if (!string.IsNullOrEmpty(title) && !string.IsNullOrEmpty(artist))
+                            {
+                                await _lrclibService.GetLyricsAsync(title, artist, null, null);
+                            }
+                        }
+                    }
+                }
+                catch (Exception ex)
+                {
+                    _logger.LogDebug(ex, "Failed to pre-fetch lyrics for search results");
+                }
+            });
+        }
+
         // Filter by item types if specified
         var items = new List<Dictionary<string, object?>>();
 

allstarr/Program.cs

@@ -455,6 +455,9 @@ else if (musicService == MusicService.SquidWTF)
             squidWtfApiUrls));
 }
 
+// Register ParallelMetadataService to race all registered providers for faster searches
+builder.Services.AddSingleton<ParallelMetadataService>();
+
 // Startup validation - register validators based on backend
 if (backendType == BackendType.Jellyfin)
 {

allstarr/Services/Common/ParallelMetadataService.cs

@@ -0,0 +1,135 @@
+using allstarr.Models.Domain;
+using allstarr.Models.Search;
+
+namespace allstarr.Services.Common;
+
+/// <summary>
+/// Races multiple metadata providers in parallel and returns the fastest result.
+/// Used for search operations to minimize latency.
+/// </summary>
+public class ParallelMetadataService
+{
+    private readonly IEnumerable<IMusicMetadataService> _providers;
+    private readonly ILogger<ParallelMetadataService> _logger;
+
+    public ParallelMetadataService(
+        IEnumerable<IMusicMetadataService> providers,
+        ILogger<ParallelMetadataService> logger)
+    {
+        _providers = providers;
+        _logger = logger;
+    }
+
+    /// <summary>
+    /// Races all providers and returns the first successful result.
+    /// Falls back to next provider if first one fails.
+    /// </summary>
+    public async Task<SearchResult> SearchAllAsync(string query, int songLimit = 20, int albumLimit = 20, int artistLimit = 20)
+    {
+        if (!_providers.Any())
+        {
+            _logger.LogWarning("No metadata providers available for parallel search");
+            return new SearchResult();
+        }
+
+        _logger.LogDebug("🏁 Racing {Count} providers for search: {Query}", _providers.Count(), query);
+
+        // Create tasks for all providers
+        var tasks = _providers.Select(async provider =>
+        {
+            var providerName = provider.GetType().Name;
+            try
+            {
+                var sw = System.Diagnostics.Stopwatch.StartNew();
+                var result = await provider.SearchAllAsync(query, songLimit, albumLimit, artistLimit);
+                sw.Stop();
+                
+                _logger.LogInformation("✅ {Provider} completed search in {Ms}ms ({Songs} songs, {Albums} albums, {Artists} artists)",
+                    providerName, sw.ElapsedMilliseconds, result.Songs.Count, result.Albums.Count, result.Artists.Count);
+                
+                return (Success: true, Result: result, Provider: providerName, ElapsedMs: sw.ElapsedMilliseconds);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "❌ {Provider} search failed", providerName);
+                return (Success: false, Result: new SearchResult(), Provider: providerName, ElapsedMs: 0L);
+            }
+        }).ToList();
+
+        // Wait for first successful result
+        while (tasks.Any())
+        {
+            var completedTask = await Task.WhenAny(tasks);
+            var result = await completedTask;
+
+            if (result.Success && (result.Result.Songs.Any() || result.Result.Albums.Any() || result.Result.Artists.Any()))
+            {
+                _logger.LogInformation("🏆 Using results from {Provider} ({Ms}ms) - fastest with results",
+                    result.Provider, result.ElapsedMs);
+                return result.Result;
+            }
+
+            // Remove completed task and try next
+            tasks.Remove(completedTask);
+        }
+
+        // All providers failed or returned empty
+        _logger.LogWarning("⚠️ All providers failed or returned empty results for: {Query}", query);
+        return new SearchResult();
+    }
+
+    /// <summary>
+    /// Searches for a specific song by title and artist across all providers in parallel.
+    /// Returns the first successful match.
+    /// </summary>
+    public async Task<Song?> SearchSongAsync(string title, string artist, int limit = 5)
+    {
+        if (!_providers.Any())
+        {
+            return null;
+        }
+
+        _logger.LogDebug("🏁 Racing {Count} providers for song: {Title} - {Artist}", _providers.Count(), title, artist);
+
+        var tasks = _providers.Select(async provider =>
+        {
+            var providerName = provider.GetType().Name;
+            try
+            {
+                var sw = System.Diagnostics.Stopwatch.StartNew();
+                var songs = await provider.SearchSongsAsync($"{title} {artist}", limit);
+                sw.Stop();
+                
+                var bestMatch = songs.FirstOrDefault();
+                if (bestMatch != null)
+                {
+                    _logger.LogInformation("✅ {Provider} found song in {Ms}ms", providerName, sw.ElapsedMilliseconds);
+                }
+                
+                return (Success: bestMatch != null, Song: bestMatch, Provider: providerName, ElapsedMs: sw.ElapsedMilliseconds);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "❌ {Provider} song search failed", providerName);
+                return (Success: false, Song: (Song?)null, Provider: providerName, ElapsedMs: 0L);
+            }
+        }).ToList();
+
+        // Wait for first successful result
+        while (tasks.Any())
+        {
+            var completedTask = await Task.WhenAny(tasks);
+            var result = await completedTask;
+
+            if (result.Success && result.Song != null)
+            {
+                _logger.LogInformation("🏆 Using song from {Provider} ({Ms}ms)", result.Provider, result.ElapsedMs);
+                return result.Song;
+            }
+
+            tasks.Remove(completedTask);
+        }
+
+        return null;
+    }
+}