fix(jellyfin): preserve routed provider identities

allstarr.Tests/Protocols/ProtocolRouteFixtureTests.cs

@@ -2381,6 +2381,7 @@ public sealed class ProtocolRouteFixtureTests
         var actual = JsonNode.Parse(
             tracks.RootElement.GetProperty("Items")[0].GetRawText())!.AsObject();
         var expected = JsonNode.Parse(originalItem)!.AsObject();
+        expected["ProviderIds"]!["AllstarrSource"] = "spotify";
         expected["ParentId"] = virtualId;
         expected["PlaylistItemId"] = "local-song-a";
 
@@ -2389,7 +2390,7 @@ public sealed class ProtocolRouteFixtureTests
             $"Expected full source DTO with playlist overlays.\nExpected: {expected}\nActual: {actual}");
         Assert.Equal("Original Track", actual["Name"]!.GetValue<string>());
         Assert.Equal(virtualId, actual["ParentId"]!.GetValue<string>());
-        Assert.False(actual["ProviderIds"]!.AsObject().ContainsKey("AllstarrSource"));
+        Assert.Equal("spotify", actual["ProviderIds"]!["AllstarrSource"]!.GetValue<string>());
         Assert.Equal("local-song-a", actual["Id"]!.GetValue<string>());
         Assert.Equal("local-song-a", actual["PlaylistItemId"]!.GetValue<string>());
         Assert.Equal("album-original", actual["AlbumId"]!.GetValue<string>());

allstarr.Tests/Providers/DeezerMetadataCapabilityAdapterTests.cs

@@ -253,7 +253,7 @@ public sealed class DeezerMetadataCapabilityAdapterTests
             ]);
         legacy.Setup(item => item.GetArtistTracksAsync("deezer", "artist-1", It.IsAny<CancellationToken>()))
             .ReturnsAsync([
-                new Song { ExternalId = "track-1", Title = "First", Artist = "Artist", Artists = ["Artist"] },
+                new Song { ExternalId = "track-1", Title = "First", Artist = "Artist", Artists = ["Artist"], ArtistId = "artist-1" },
                 new Song { ExternalId = "track-2", Title = "Second", Artist = "Artist", Artists = ["Artist"] }
             ]);
         var adapter = new DeezerMetadataCapabilityAdapter(legacy.Object);
@@ -272,6 +272,7 @@ public sealed class DeezerMetadataCapabilityAdapterTests
         Assert.Equal("album-3", Assert.Single(remaining.Items).Id.Value);
         Assert.Null(remaining.NextCursor);
         Assert.Equal(["track-1", "track-2"], tracks.Items.Select(item => item.Id.Value));
+        Assert.Equal("artist-1", tracks.Items[0].Artists[0].ArtistId!.Value);
         legacy.VerifyAll();
     }
 

allstarr/Core/Protocols/Jellyfin/JellyfinVirtualPlaylistProtocolAdapter.cs

@@ -314,6 +314,13 @@ public sealed class JellyfinVirtualPlaylistProtocolAdapter(
                 }
             }
 
+            if (track.RouteKind == TrackRouteKind.Local &&
+                !string.IsNullOrWhiteSpace(track.SourceProviderId))
+            {
+                var providerIds = item["ProviderIds"] as JsonObject ?? [];
+                item["ProviderIds"] = providerIds;
+                providerIds["AllstarrSource"] = track.SourceProviderId;
+            }
             item["ParentId"] = responsePlaylistId;
             item["PlaylistItemId"] = track.NativePlaylistEntryId ?? track.BackendItemId;
             return item;

allstarr/Core/Providers/ConcreteMetadataCapabilityAdapter.cs

@@ -210,11 +210,17 @@ public abstract class ConcreteMetadataCapabilityAdapter(
         if (names.Length == 0)
             throw new InvalidOperationException($"The {ProviderId} track has no artist credit.");
 
-        var credits = names.Select((name, index) => new ProviderArtistCredit(
-            name.Trim(),
-            index < song.ArtistIds.Count && !string.IsNullOrWhiteSpace(song.ArtistIds[index])
-                ? ExternalId(ProviderResourceKind.Artist, song.ArtistIds[index], null, "artist")
-                : null));
+        var credits = names.Select((name, index) =>
+        {
+            var artistId = index < song.ArtistIds.Count && !string.IsNullOrWhiteSpace(song.ArtistIds[index])
+                ? song.ArtistIds[index]
+                : index == 0 ? song.ArtistId : null;
+            return new ProviderArtistCredit(
+                name.Trim(),
+                string.IsNullOrWhiteSpace(artistId)
+                    ? null
+                    : ExternalId(ProviderResourceKind.Artist, artistId, null, "artist"));
+        });
         var albumId = string.IsNullOrWhiteSpace(song.AlbumId)
             ? null
             : ExternalId(ProviderResourceKind.Album, song.AlbumId, null, "album");