Checkpoint web-player design-system refactor and backend track genre tagging

Advances the ongoing token/componentization cleanup (anchored player dock,
border-based panels instead of floating shadows, corrected light-mode
accent/gradient tokens) alongside in-progress backend support for track
genre tags.

backend/Tests/Musify.Application.Tests/TestSupport/TestDatabase.cs

@@ -95,6 +95,16 @@ namespace Musify.Application.Tests.TestSupport
                 .HasIndex(like => new { like.UserId, like.TrackId })
                 .IsUnique();
 
+            modelBuilder.Entity<TrackTag>()
+                .HasOne(trackTag => trackTag.Track)
+                .WithMany(track => track.Tags)
+                .HasForeignKey(trackTag => trackTag.TrackId)
+                .OnDelete(DeleteBehavior.Cascade);
+
+            modelBuilder.Entity<TrackTag>()
+                .HasIndex(trackTag => new { trackTag.TrackId, trackTag.Tag })
+                .IsUnique();
+
             modelBuilder.Entity<UserFollow>()
                 .HasOne(follow => follow.Follower)
                 .WithMany()
@@ -138,6 +148,8 @@ namespace Musify.Application.Tests.TestSupport
 
         public DbSet<TrackLike> TrackLikes => Set<TrackLike>();
 
+        public DbSet<TrackTag> TrackTags => Set<TrackTag>();
+
         public DbSet<UserFollow> UserFollows => Set<UserFollow>();
 
         public async Task<IDatabaseTransaction> BeginTransactionAsync(System.Data.IsolationLevel isolationLevel, CancellationToken cancellationToken)

backend/Tests/Musify.Application.Tests/TestSupport/TestEntities.cs

@@ -55,8 +55,10 @@ namespace Musify.Application.Tests.TestSupport
             double durationSeconds = 180,
             TrackPictures? pictures = null,
             TrackAudio? audio = null,
-            LifeCycleStatus lifeCycleStatus = LifeCycleStatus.Active) =>
-            new()
+            LifeCycleStatus lifeCycleStatus = LifeCycleStatus.Active,
+            IEnumerable<Genre>? tags = null)
+        {
+            var track = new Track
             {
                 Title = title,
                 NormalizedTitle = title.ToUpperInvariant(),
@@ -68,6 +70,13 @@ namespace Musify.Application.Tests.TestSupport
                 Audio = audio ?? ProcessedAudio()
             };
 
+            track.Tags = (tags ?? [Genre.Pop])
+                .Select(tag => new TrackTag { TrackId = track.Id, Tag = tag })
+                .ToList();
+
+            return track;
+        }
+
         public static PlayListPictures PlayListPictures() => new()
         {
             OriginalName = "original.webp",

backend/Tests/Musify.Application.Tests/Tracks/CreateTrackCommandHandlerTests.cs

@@ -42,7 +42,7 @@ namespace Musify.Application.Tests.Tracks
             var (picture, audio) = SeedIntents(user.Id);
             await SeedAsync(user, picture, audio);
 
-            var command = new CreateTrackCommand(user.Id, "My Song", picture.Id, audio.Id);
+            var command = new CreateTrackCommand(user.Id, "My Song", picture.Id, audio.Id, [Genre.Pop, Genre.Rock]);
 
             var result = await CreateHandler().Handle(command, TestContext.Current.CancellationToken);
 
@@ -50,6 +50,7 @@ namespace Musify.Application.Tests.Tracks
             Assert.Equal("My Song", result.Value.Title);
             var localResponse = Assert.IsType<TrackApplicationResponse>(result.Value);
             Assert.Equal(user.Id, localResponse.OwnerUserId);
+            Assert.Equal([Genre.Pop, Genre.Rock], localResponse.Tags);
             await eventBus.Received(1).PublishAsync(Arg.Any<Musify.Application.Events.CreateTrackResourcesEvent>(), Arg.Any<CancellationToken>());
 
             var stored = await Database.Tracks.FindAsync([result.Value.Id], TestContext.Current.CancellationToken);
@@ -57,10 +58,38 @@ namespace Musify.Application.Tests.Tracks
             Assert.Equal(ProcessingStatus.Pending, stored.Audio.TranscodeStatus);
         }
 
+        [Fact]
+        public async Task Handle_NoTags_ReturnsValidationError()
+        {
+            var user = TestEntities.User();
+            var (picture, audio) = SeedIntents(user.Id);
+            await SeedAsync(user, picture, audio);
+
+            var command = new CreateTrackCommand(user.Id, "My Song", picture.Id, audio.Id, []);
+
+            var result = await CreateHandler().Handle(command, TestContext.Current.CancellationToken);
+
+            Assert.Equal(ErrorType.Validation, result.FirstError.Type);
+        }
+
+        [Fact]
+        public async Task Handle_IncompatibleTags_ReturnsValidationError()
+        {
+            var user = TestEntities.User();
+            var (picture, audio) = SeedIntents(user.Id);
+            await SeedAsync(user, picture, audio);
+
+            var command = new CreateTrackCommand(user.Id, "My Song", picture.Id, audio.Id, [Genre.Classical, Genre.Metal]);
+
+            var result = await CreateHandler().Handle(command, TestContext.Current.CancellationToken);
+
+            Assert.Equal(ErrorType.Validation, result.FirstError.Type);
+        }
+
         [Fact]
         public async Task Handle_UserMissing_ReturnsNotFound()
         {
-            var command = new CreateTrackCommand(404, "Orphan Song", Guid.NewGuid(), Guid.NewGuid());
+            var command = new CreateTrackCommand(404, "Orphan Song", Guid.NewGuid(), Guid.NewGuid(), [Genre.Pop]);
 
             var result = await CreateHandler().Handle(command, TestContext.Current.CancellationToken);
 
@@ -75,7 +104,7 @@ namespace Musify.Application.Tests.Tracks
             var (picture, audio) = SeedIntents(otherUser.Id);
             await SeedAsync(user, otherUser, picture, audio);
 
-            var command = new CreateTrackCommand(user.Id, "My Song", picture.Id, audio.Id);
+            var command = new CreateTrackCommand(user.Id, "My Song", picture.Id, audio.Id, [Genre.Pop]);
 
             var result = await CreateHandler().Handle(command, TestContext.Current.CancellationToken);
 
@@ -91,7 +120,7 @@ namespace Musify.Application.Tests.Tracks
             var audio = TestEntities.UploadIntent(user.Id, UploadIntentPurpose.TrackAudio, objectName: "song.mp3", status: UploadIntentStatus.Consumed);
             await SeedAsync(user, picture, audio);
 
-            var command = new CreateTrackCommand(user.Id, "My Song", picture.Id, audio.Id);
+            var command = new CreateTrackCommand(user.Id, "My Song", picture.Id, audio.Id, [Genre.Pop]);
 
             var result = await CreateHandler().Handle(command, TestContext.Current.CancellationToken);
 

backend/Tests/Musify.Domain.Tests/ValueObjects/GenreCompatibilityTests.cs

@@ -0,0 +1,51 @@
+using Musify.Domain.ValueObjects;
+using Xunit;
+
+namespace Musify.Domain.Tests.ValueObjects
+{
+    public sealed class GenreCompatibilityTests
+    {
+        [Theory]
+        [InlineData(Genre.Classical, Genre.Metal)]
+        [InlineData(Genre.Classical, Genre.Punk)]
+        [InlineData(Genre.Ambient, Genre.Dubstep)]
+        [InlineData(Genre.Lofi, Genre.DrumAndBass)]
+        public void AreCompatible_IncompatiblePair_ReturnsFalse(Genre first, Genre second)
+        {
+            Assert.False(GenreCompatibility.AreCompatible(first, second));
+            Assert.False(GenreCompatibility.AreCompatible(second, first));
+        }
+
+        [Theory]
+        [InlineData(Genre.Pop, Genre.Rock)]
+        [InlineData(Genre.HipHop, Genre.RnB)]
+        [InlineData(Genre.Classical, Genre.Jazz)]
+        public void AreCompatible_CompatiblePair_ReturnsTrue(Genre first, Genre second)
+        {
+            Assert.True(GenreCompatibility.AreCompatible(first, second));
+        }
+
+        [Fact]
+        public void AreCompatible_SameGenre_ReturnsTrue()
+        {
+            Assert.True(GenreCompatibility.AreCompatible(Genre.Pop, Genre.Pop));
+        }
+
+        [Fact]
+        public void FindConflicts_NoIncompatiblePairs_ReturnsEmpty()
+        {
+            var conflicts = GenreCompatibility.FindConflicts([Genre.Pop, Genre.Rock, Genre.Indie]);
+
+            Assert.Empty(conflicts);
+        }
+
+        [Fact]
+        public void FindConflicts_IncompatiblePairPresent_ReturnsIt()
+        {
+            var conflicts = GenreCompatibility.FindConflicts([Genre.Pop, Genre.Classical, Genre.Metal]);
+
+            var conflict = Assert.Single(conflicts);
+            Assert.Equal((Genre.Classical, Genre.Metal), conflict);
+        }
+    }
+}

backend/Tests/Musify.Infrastructure.Tests/Persistence/DatabaseTests.cs

@@ -41,6 +41,31 @@ namespace Musify.Infrastructure.Tests.Persistence
             Assert.Equal(user.Id, stored.OwnerUserId);
         }
 
+        [Fact]
+        public async Task SaveChangesAsync_TrackWithTags_RoundTripsThroughNativePostgresEnum()
+        {
+            await using var database = fixture.CreateDatabase();
+
+            var userName = "tags-roundtrip-user";
+            var user = new User { Id = Random.Shared.NextInt64(1, long.MaxValue), Name = userName, NormalizedName = userName.ToUpperInvariant() };
+            var track = BuildTrack(user, $"tags-{Guid.NewGuid():N}");
+            track.Tags =
+            [
+                new TrackTag { TrackId = track.Id, Tag = Genre.Pop },
+                new TrackTag { TrackId = track.Id, Tag = Genre.Rock }
+            ];
+
+            await database.AddRangeAsync(user, track);
+            await database.SaveChangesAsync(TestContext.Current.CancellationToken);
+
+            await using var reloaded = fixture.CreateDatabase();
+            var stored = await reloaded.Tracks.AsNoTracking()
+                .Include(t => t.Tags)
+                .SingleAsync(t => t.Id == track.Id, TestContext.Current.CancellationToken);
+
+            Assert.Equal([Genre.Pop, Genre.Rock], stored.Tags.Select(t => t.Tag).OrderBy(t => t));
+        }
+
         [Fact]
         public async Task AlbumHasTracks_DeletingAlbum_CascadesToTheLinkRows()
         {