Separate responsibilities: start-listening command, API-side JSON converters, bulk track endpoints, mix kinds

backend/Core/Musify.Application/Tracks/CreateTrack.cs

@@ -41,21 +41,6 @@ public class CreateTrackCommandHandler(
         }
 
         var distinctTags = request.Tags.Distinct().ToList();
-        if (distinctTags.Count == 0)
-        {
-            logger.LogWarning("Track {Title} was submitted without any tags", request.Title);
-            return Error.Validation(description: "At least one tag is required.");
-        }
-
-        var tagConflicts = GenreCompatibility.FindConflicts(distinctTags);
-        if (tagConflicts.Count > 0)
-        {
-            var conflict = tagConflicts.First();
-            logger.LogWarning(
-                "Track {Title} was submitted with incompatible tags {First} and {Second}",
-                request.Title, conflict.First, conflict.Second);
-            return Error.Validation(description: $"Tags '{conflict.First}' and '{conflict.Second}' are not compatible.");
-        }
 
         if (request.PictureIntentId == request.AudioIntentId)
             return Error.Validation(description: "Picture and audio must use different upload intents.");
@@ -105,11 +90,6 @@ public class CreateTrackCommandHandler(
 
         await database.Tracks.AddAsync(trackEntity, cancellationToken);
 
-        await database.UserHasTracks.AddAsync(new UserHasTrack
-        {
-            UserId = request.UserId,
-            TrackId = trackEntity.Id
-        }, cancellationToken);
 
         var sizes = trackConfiguration.PicturesSizes.ToImageSizes(trackConfiguration.Routes);
         await eventBus.PublishAsync(

backend/Core/Musify.Application/Tracks/RecordListeningProgress.cs

@@ -17,9 +17,6 @@ public class RecordListeningProgressCommandHandler(IDatabase database)
 {
     public async ValueTask<ErrorOr<Success>> Handle(RecordListeningProgressCommand request, CancellationToken cancellationToken)
     {
-        if (!double.IsFinite(request.PlayedSeconds) || request.PlayedSeconds < 0)
-            return Error.Validation(description: "playedSeconds must be a non-negative number.");
-
         var listen = await database.ListeningHistories
             .Include(l => l.Track)
             .SingleOrDefaultAsync(l => l.Id == request.ListenId && l.UserId == request.UserId, cancellationToken);

backend/Core/Musify.Application/Tracks/Responses/TrackApplicationResponse.cs

@@ -1,5 +1,3 @@
-using System.Text.Json.Serialization;
-using Musify.Application.Serialization;
 using Musify.Domain.Entities;
 using Musify.Domain.ValueObjects;
 
@@ -14,7 +12,7 @@ public record TrackApplicationResponse(
     int ListensCount,
     DateTime CreatedAt,
     DateTime UpdatedAt,
-    [property: JsonConverter(typeof(LongAsStringConverter))] long OwnerUserId,
+    long OwnerUserId,
     IReadOnlyCollection<Genre> Tags,
     bool IsExplicit)
 {

backend/Core/Musify.Application/Tracks/StartListening.cs

@@ -5,24 +5,25 @@ using Microsoft.Extensions.Logging;
 using Musify.Application.Configuration;
 using Musify.Application.Contracts;
 using Musify.Application.Services;
-using Musify.Application.Tracks.Responses;
-using Musify.Domain.ValueObjects;
 using Musify.Application.Shared;
+using Musify.Application.Tracks.Responses;
+using Musify.Domain.Entities;
+using Musify.Domain.ValueObjects;
 
 namespace Musify.Application.Tracks;
 
+/// <summary>Starts a listen: records it for signed-in users and issues the stream ticket.</summary>
+public record StartListeningCommand(Guid TrackId, long? UserId)
+    : ICommand<ErrorOr<TrackStreamResponse>>;
 
-public record GetTrackStreamQuery(Guid TrackId, long? UserId)
-    : IQuery<ErrorOr<TrackStreamResponse>>;
-
-public class GetTrackStreamQueryHandler(
+public class StartListeningCommandHandler(
     IDatabase database,
     TrackStreamIssuer streamIssuer,
     PlaybackConfiguration playbackConfiguration,
-    ILogger<GetTrackStreamQueryHandler> logger)
-    : IQueryHandler<GetTrackStreamQuery, ErrorOr<TrackStreamResponse>>
+    ILogger<StartListeningCommandHandler> logger)
+    : ICommandHandler<StartListeningCommand, ErrorOr<TrackStreamResponse>>
 {
-    public async ValueTask<ErrorOr<TrackStreamResponse>> Handle(GetTrackStreamQuery request, CancellationToken cancellationToken)
+    public async ValueTask<ErrorOr<TrackStreamResponse>> Handle(StartListeningCommand request, CancellationToken cancellationToken)
     {
         if (request.UserId == null && !playbackConfiguration.AllowAnonymousListening)
             return Error.Unauthorized(description: "Sign in to stream music, or ask an administrator to enable anonymous listening.");
@@ -38,10 +39,17 @@ public class GetTrackStreamQueryHandler(
         if (!track.Audio.IsProcessed)
             return AppErrors.Conflict("Track.AudioNotReady", "Track audio is not available for streaming yet.");
 
-        var response = await streamIssuer.IssueAsync(track.Id, track.Audio.FolderName, request.UserId, cancellationToken);
+        Guid? listenId = null;
+        if (request.UserId is { } userId)
+        {
+            var listen = new ListeningHistory { UserId = userId, TrackId = track.Id };
+            await database.ListeningHistories.AddAsync(listen, cancellationToken);
+            await database.SaveChangesAsync(cancellationToken);
+            listenId = listen.Id;
+        }
 
         logger.LogInformation("Issued stream ticket for track {TrackId} to user {UserId}", request.TrackId, request.UserId?.ToString() ?? "(anonymous)");
 
-        return response;
+        return streamIssuer.Issue(track.Audio.FolderName, request.UserId, listenId);
     }
 }