Add likes, follows and playlist visibility; redesign web-player UI

Backend:
- New Likes feature (toggle/get liked tracks) and endpoints
- User follow/unfollow, listening stats, public user profile
- Playlist visibility (public/private) support
- Various auth and DTO/response adjustments to support the above

Frontend (web-player):
- New design system pass: theme tokens/mode (light/dark), glass menu,
  tabs bar, player dock/extras/queue components, mix tiles, artist link
- New routes: Liked, public user profile (/u/[id]), likes API proxy
- Search refactor: shared SearchBox component used by TopBar and
  MobileHeader (search now reachable on mobile), live results as you
  type instead of requiring Enter, dropped the "Buscando…" quick-result
  preview
- Removed now-unused components (MobileNav, CoverBadge, MixBentoTile,
  PlayPauseOverlay, SuggestionsTable, userDirectory)
- Design handoff reference docs added under web-player/design_handoff_musify_player
  and web-player/docs/design-system-refactor-plan.md

backend/Core/Musify.Application/Albums/Responses/AlbumApplicationResponse.cs

@@ -1,5 +1,6 @@
 using System.Text.Json.Serialization;
 using Musify.Domain.Entities;
+using Musify.Application.Serialization;
 
 namespace Musify.Application.Albums.Responses
 {
@@ -17,7 +18,7 @@ namespace Musify.Application.Albums.Responses
         string Title,
         string? Description,
         int? ReleaseYear,
-        long OwnerUserId,
+        [property: JsonConverter(typeof(LongAsStringConverter))] long OwnerUserId,
         int TrackCount,
         string? SmallImageKeyName,
         string? MediumImageKeyName,

backend/Core/Musify.Application/Contracts/IDatabase.cs

@@ -41,6 +41,10 @@ namespace Musify.Application.Contracts
 
         DbSet<ListeningHistory> ListeningHistories { get; }
 
+        DbSet<TrackLike> TrackLikes { get; }
+
+        DbSet<UserFollow> UserFollows { get; }
+
         Task<IDatabaseTransaction> BeginTransactionAsync(System.Data.IsolationLevel isolationLevel, CancellationToken cancellationToken);
 
         Task<int> SaveChangesAsync(CancellationToken cancellationToken);

backend/Core/Musify.Application/Likes/GetLikedTracks.cs

@@ -0,0 +1,45 @@
+using ErrorOr;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Contracts;
+using Musify.Application.Shared;
+using Musify.Application.Tracks.Responses;
+using Musify.Domain.Entities;
+using X.PagedList;
+using X.PagedList.EF;
+
+namespace Musify.Application.Likes
+{
+    public record GetLikedTracksQuery(
+        long UserId,
+        int PageNumber,
+        int PageSize)
+        : IQuery<ErrorOr<PaginatedResponse<TrackApplicationResponse>>>;
+
+    public class GetLikedTracksQueryHandler(IDatabase database)
+        : IQueryHandler<GetLikedTracksQuery, ErrorOr<PaginatedResponse<TrackApplicationResponse>>>
+    {
+        public async ValueTask<ErrorOr<PaginatedResponse<TrackApplicationResponse>>> Handle(GetLikedTracksQuery request, CancellationToken cancellationToken)
+        {
+            var likesQuery = database.TrackLikes
+                .AsNoTracking()
+                .Include(like => ((ExternalTrack)like.Track).TrackArtists)
+                    .ThenInclude(trackArtist => trackArtist.Artist)
+                .Include(like => ((LocalTrack)like.Track).Owner)
+                .Where(like => like.UserId == request.UserId);
+
+            var totalCount = await likesQuery.CountAsync(cancellationToken);
+
+            var pagedEntities = await likesQuery
+                .OrderByDescending(like => like.CreatedAt)
+                .Select(like => new { like.Track, ListensCount = like.Track.ListeningHistories.Count })
+                .ToPagedListAsync(request.PageNumber, request.PageSize, totalCount, cancellationToken);
+
+            var pagedTracks = new StaticPagedList<TrackApplicationResponse>(
+                pagedEntities.Select(x => TrackApplicationResponse.FromEntity(x.Track, x.ListensCount)),
+                pagedEntities.PageNumber, pagedEntities.PageSize, pagedEntities.TotalItemCount);
+
+            return PaginatedResponse<TrackApplicationResponse>.FromPagedList(pagedTracks);
+        }
+    }
+}

backend/Core/Musify.Application/Likes/ToggleTrackLike.cs

@@ -0,0 +1,83 @@
+using ErrorOr;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Contracts;
+using Musify.Application.Services;
+using Musify.Domain.Entities;
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Application.Likes
+{
+    public record ToggleTrackLikeCommand(
+        long UserId,
+        Guid? TrackId,
+        TrackSource? Source,
+        string? ExternalId)
+        : ICommand<ErrorOr<bool>>;
+
+    public class ToggleTrackLikeCommandHandler(
+        IDatabase database,
+        YouTubeTrackProvisioner provisioner,
+        ILogger<ToggleTrackLikeCommandHandler> logger)
+        : ICommandHandler<ToggleTrackLikeCommand, ErrorOr<bool>>
+    {
+        public async ValueTask<ErrorOr<bool>> Handle(ToggleTrackLikeCommand request, CancellationToken cancellationToken)
+        {
+            var trackIdResult = await ResolveTrackIdAsync(request, cancellationToken);
+            if (trackIdResult.IsError)
+                return trackIdResult.Errors;
+
+            var trackId = trackIdResult.Value;
+
+            var existingLike = await database.TrackLikes
+                .SingleOrDefaultAsync(like => like.UserId == request.UserId && like.TrackId == trackId, cancellationToken);
+
+            bool nowLiked;
+            if (existingLike is not null)
+            {
+                database.TrackLikes.Remove(existingLike);
+                nowLiked = false;
+            }
+            else
+            {
+                await database.TrackLikes.AddAsync(new TrackLike
+                {
+                    UserId = request.UserId,
+                    TrackId = trackId
+                }, cancellationToken);
+                nowLiked = true;
+            }
+
+            await database.SaveChangesAsync(cancellationToken);
+
+            logger.LogInformation("User {UserId} {Action} track {TrackId}",
+                request.UserId, nowLiked ? "liked" : "unliked", trackId);
+
+            return nowLiked;
+        }
+
+        private async ValueTask<ErrorOr<Guid>> ResolveTrackIdAsync(ToggleTrackLikeCommand request, CancellationToken cancellationToken)
+        {
+            if (request.TrackId.HasValue)
+            {
+                var trackExists = await database.Tracks
+                    .AsNoTracking()
+                    .AnyAsync(t => t.Id == request.TrackId.Value, cancellationToken);
+                if (!trackExists)
+                {
+                    logger.LogInformation("Track {TrackId} not found", request.TrackId);
+                    return Error.NotFound(description: $"Track {request.TrackId} not found");
+                }
+
+                return request.TrackId.Value;
+            }
+
+            var provisionResult = await provisioner.GetOrCreateAsync(request.ExternalId!, cancellationToken);
+            if (provisionResult.IsError)
+                return provisionResult.Errors;
+
+            return provisionResult.Value.Track.Id;
+        }
+    }
+}

backend/Core/Musify.Application/PlayLists/CreatePlayList.cs

@@ -17,7 +17,8 @@ namespace Musify.Application.PlayLists
         long UserId,
         string Name,
         string? Description,
-        Guid? PictureIntentId)
+        Guid? PictureIntentId,
+        PlaylistVisibility Visibility = PlaylistVisibility.Private)
         : ICommand<ErrorOr<PlayListApplicationResponse>>;
 
     public class CreatePlayListCommandHandler(
@@ -55,7 +56,8 @@ namespace Musify.Application.PlayLists
                 Name = request.Name,
                 NormalizedName = request.Name.Trim().ToUpperInvariant(),
                 Description = string.IsNullOrWhiteSpace(request.Description)? null: request.Description.Trim(),
-                Pictures = resolvedPictures.Pictures
+                Pictures = resolvedPictures.Pictures,
+                Visibility = request.Visibility
             };
             await database.PlayLists.AddAsync(playList, cancellationToken);
 

backend/Core/Musify.Application/PlayLists/GetPlayListById.cs

@@ -3,10 +3,11 @@ using Microsoft.EntityFrameworkCore;
 using Musify.Application.PlayLists.Responses;
 using Mediator;
 using Musify.Application.Contracts;
+using Musify.Domain.ValueObjects;
 
 namespace Musify.Application.PlayLists
 {
-    public record GetPlayListByIdQuery(Guid Id)
+    public record GetPlayListByIdQuery(Guid Id, long? RequestingUserId = null)
         : IQuery<ErrorOr<PlayListApplicationResponse>>;
 
     public class GetPlayListByIdQueryHandler(IDatabase database)
@@ -31,6 +32,10 @@ namespace Musify.Application.PlayLists
             if (entry is null)
                 return Error.NotFound();
 
+            if (entry.PlayList.Visibility == PlaylistVisibility.Private
+                && entry.PlayList.UserId != request.RequestingUserId)
+                return Error.NotFound();
+
             return PlayListApplicationResponse.FromEntity(entry.PlayList, entry.CoverTrackIds);
         }
     }

backend/Core/Musify.Application/PlayLists/GetPlayListsByUserId.cs

@@ -14,7 +14,8 @@ namespace Musify.Application.PlayLists
         long UserId,
         string? Name,
         int PageNumber,
-        int PageSize)
+        int PageSize,
+        bool OnlyPublic = false)
         : IQuery<ErrorOr<PaginatedResponse<PlayListApplicationResponse>> >;
 
     public class GetPlayListsByUserIdQueryHandler(IDatabase database)
@@ -26,6 +27,11 @@ namespace Musify.Application.PlayLists
                 .AsNoTracking()
                 .Where(p => p.UserId == request.UserId);
 
+            if (request.OnlyPublic)
+            {
+                playListsQuery = playListsQuery.Where(p => p.Visibility == PlaylistVisibility.Public);
+            }
+
             if (!string.IsNullOrEmpty(request.Name))
             {
                 var normalizedName = request.Name.Trim().ToUpperInvariant();

backend/Core/Musify.Application/PlayLists/Responses/PlayListApplicationResponse.cs

@@ -1,4 +1,5 @@
 using Musify.Domain.Entities;
+using Musify.Domain.ValueObjects;
 
 namespace Musify.Application.PlayLists.Responses
 {
@@ -9,6 +10,7 @@ namespace Musify.Application.PlayLists.Responses
         string? SmallImageKeyName,
         string? MediumImageKeyName,
         string? LargeImageKeyName,
+        PlaylistVisibility Visibility,
         DateTime CreatedAt,
         DateTime UpdatedAt,
         IReadOnlyList<Guid> CoverTrackIds)
@@ -26,6 +28,7 @@ namespace Musify.Application.PlayLists.Responses
                 playList.Pictures?.SmallName,
                 playList.Pictures?.MediumName,
                 playList.Pictures?.LargeName,
+                playList.Visibility,
                 playList.CreatedAt,
                 playList.UpdatedAt,
                 coverTrackIds ?? []);

backend/Core/Musify.Application/PlayLists/UpdatePlayList.cs

@@ -18,7 +18,8 @@ namespace Musify.Application.PlayLists
         Guid PlayListId,
         string? NewName,
         string? NewDescription,
-        Guid? NewPictureIntentId)
+        Guid? NewPictureIntentId,
+        PlaylistVisibility? NewVisibility = null)
         : ICommand<ErrorOr<PlayListApplicationResponse>>;
 
     public class UpdatePlayListCommandHandler(
@@ -57,6 +58,11 @@ namespace Musify.Application.PlayLists
                 playListEntity.Description = request.NewDescription;
             }
 
+            if (request.NewVisibility.HasValue)
+            {
+                playListEntity.Visibility = request.NewVisibility.Value;
+            }
+
             UploadIntent? pictureIntent = null;
             string? finalPictureKey = null;
 

backend/Core/Musify.Application/Serialization/LongAsStringConverter.cs

@@ -0,0 +1,44 @@
+using System.Globalization;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace Musify.Application.Serialization;
+
+// Zitadel-issued user ids routinely exceed Number.MAX_SAFE_INTEGER (2^53-1).
+// Serialized as a raw JSON number, the frontend's JSON.parse silently rounds
+// them to the nearest representable double, corrupting the id (it becomes a
+// different, sometimes valid, user id). Applied via [property: JsonConverter(...)]
+// on the specific id-shaped `long`/`long?` response properties (not globally —
+// unrelated `long` fields like byte sizes must stay numbers), this serializes
+// them as a JSON string instead, which round-trips exactly.
+public sealed class LongAsStringConverter : JsonConverter<long>
+{
+    public override long Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options) =>
+        reader.TokenType == JsonTokenType.String
+            ? long.Parse(reader.GetString()!, CultureInfo.InvariantCulture)
+            : reader.GetInt64();
+
+    public override void Write(Utf8JsonWriter writer, long value, JsonSerializerOptions options) =>
+        writer.WriteStringValue(value.ToString(CultureInfo.InvariantCulture));
+}
+
+public sealed class NullableLongAsStringConverter : JsonConverter<long?>
+{
+    public override long? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        if (reader.TokenType == JsonTokenType.Null)
+            return null;
+
+        return reader.TokenType == JsonTokenType.String
+            ? string.IsNullOrEmpty(reader.GetString()) ? null : long.Parse(reader.GetString()!, CultureInfo.InvariantCulture)
+            : reader.GetInt64();
+    }
+
+    public override void Write(Utf8JsonWriter writer, long? value, JsonSerializerOptions options)
+    {
+        if (value.HasValue)
+            writer.WriteStringValue(value.Value.ToString(CultureInfo.InvariantCulture));
+        else
+            writer.WriteNullValue();
+    }
+}

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

@@ -1,3 +1,5 @@
+using System.Text.Json.Serialization;
+using Musify.Application.Serialization;
 using Musify.Domain.Entities;
 using Musify.Domain.ValueObjects;
 
@@ -12,7 +14,7 @@ namespace Musify.Application.Tracks.Responses
         int ListensCount,
         DateTime CreatedAt,
         DateTime UpdatedAt,
-        long OwnerUserId)
+        [property: JsonConverter(typeof(LongAsStringConverter))] long OwnerUserId)
         : TrackApplicationResponse(Id, Title, Artist, AudioStatus, Duration, ListensCount, CreatedAt, UpdatedAt)
     {
         public static LocalTrackApplicationResponse FromEntity(LocalTrack track, int listensCount) =>

backend/Core/Musify.Application/Users/FollowUser.cs

@@ -0,0 +1,50 @@
+using ErrorOr;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Contracts;
+using Musify.Domain.Entities;
+
+namespace Musify.Application.Users
+{
+    public record FollowUserCommand(long FollowerId, long FollowedId) : ICommand<ErrorOr<Success>>;
+
+    public class FollowUserCommandHandler(
+        IDatabase database,
+        ILogger<FollowUserCommandHandler> logger)
+        : ICommandHandler<FollowUserCommand, ErrorOr<Success>>
+    {
+        public async ValueTask<ErrorOr<Success>> Handle(FollowUserCommand request, CancellationToken cancellationToken)
+        {
+            if (request.FollowerId == request.FollowedId)
+                return Error.Validation(description: "A user cannot follow themselves.");
+
+            var followedExists = await database.Users
+                .AsNoTracking()
+                .AnyAsync(u => u.Id == request.FollowedId, cancellationToken);
+            if (!followedExists)
+            {
+                logger.LogInformation("User {FollowedId} not found", request.FollowedId);
+                return Error.NotFound(description: $"User {request.FollowedId} not found");
+            }
+
+            var alreadyFollowing = await database.UserFollows
+                .AsNoTracking()
+                .AnyAsync(f => f.FollowerId == request.FollowerId && f.FollowedId == request.FollowedId, cancellationToken);
+            if (alreadyFollowing)
+                return new Success();
+
+            await database.UserFollows.AddAsync(new UserFollow
+            {
+                FollowerId = request.FollowerId,
+                FollowedId = request.FollowedId
+            }, cancellationToken);
+
+            await database.SaveChangesAsync(cancellationToken);
+
+            logger.LogInformation("User {FollowerId} followed user {FollowedId}", request.FollowerId, request.FollowedId);
+
+            return new Success();
+        }
+    }
+}

backend/Core/Musify.Application/Users/GetListeningStats.cs

@@ -0,0 +1,48 @@
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.Users
+{
+    public record GetListeningStatsQuery(long UserId) : IQuery<ListeningStatsResponse>;
+
+    public record ListeningStatsResponse(int TracksThisWeek, int SecondsThisWeek, int StreakDays);
+
+    public class GetListeningStatsQueryHandler(IDatabase database)
+        : IQueryHandler<GetListeningStatsQuery, ListeningStatsResponse>
+    {
+        public async ValueTask<ListeningStatsResponse> Handle(GetListeningStatsQuery request, CancellationToken cancellationToken)
+        {
+            var weekAgo = DateTime.UtcNow.AddDays(-7);
+
+            var thisWeekHistory = database.ListeningHistories
+                .Where(l => l.UserId == request.UserId && l.ListenedAt >= weekAgo);
+
+            var tracksThisWeek = await thisWeekHistory
+                .Select(l => l.TrackId)
+                .Distinct()
+                .CountAsync(cancellationToken);
+
+            var secondsThisWeek = await thisWeekHistory
+                .Join(database.Tracks, l => l.TrackId, t => t.Id, (l, t) => t.DurationSeconds)
+                .SumAsync(cancellationToken);
+
+            var listenedDates = await database.ListeningHistories
+                .Where(l => l.UserId == request.UserId)
+                .Select(l => l.ListenedAt.Date)
+                .Distinct()
+                .ToListAsync(cancellationToken);
+
+            var listenedDateSet = listenedDates.ToHashSet();
+            var streakDays = 0;
+            var day = DateTime.UtcNow.Date;
+            while (listenedDateSet.Contains(day))
+            {
+                streakDays++;
+                day = day.AddDays(-1);
+            }
+
+            return new ListeningStatsResponse(tracksThisWeek, (int)Math.Round(secondsThisWeek), streakDays);
+        }
+    }
+}

backend/Core/Musify.Application/Users/GetUserProfile.cs

@@ -0,0 +1,63 @@
+using System.Text.Json.Serialization;
+using ErrorOr;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Contracts;
+using Musify.Application.Serialization;
+
+namespace Musify.Application.Users
+{
+    public record GetUserProfileQuery(long UserId) : IQuery<ErrorOr<UserProfileResponse>>;
+
+    public record UserProfileResponse(
+        [property: JsonConverter(typeof(LongAsStringConverter))] long Id,
+        string Name,
+        string? FirstName,
+        string? SecondName,
+        string? ProfilePictureUrl,
+        DateTime CreatedAt,
+        int FollowersCount,
+        int FollowingCount);
+
+    public class GetUserProfileQueryHandler(IDatabase database)
+        : IQueryHandler<GetUserProfileQuery, ErrorOr<UserProfileResponse>>
+    {
+        public async ValueTask<ErrorOr<UserProfileResponse>> Handle(GetUserProfileQuery request, CancellationToken cancellationToken)
+        {
+            var user = await database.Users
+                .AsNoTracking()
+                .Where(u => u.Id == request.UserId)
+                .Select(u => new
+                {
+                    u.Id,
+                    u.Name,
+                    u.FirstName,
+                    u.SecondName,
+                    u.ProfilePictureUrl,
+                    u.CreatedAt
+                })
+                .SingleOrDefaultAsync(cancellationToken);
+
+            if (user is null)
+                return Error.NotFound();
+
+            var followersCount = await database.UserFollows
+                .AsNoTracking()
+                .CountAsync(f => f.FollowedId == request.UserId, cancellationToken);
+
+            var followingCount = await database.UserFollows
+                .AsNoTracking()
+                .CountAsync(f => f.FollowerId == request.UserId, cancellationToken);
+
+            return new UserProfileResponse(
+                user.Id,
+                user.Name,
+                user.FirstName,
+                user.SecondName,
+                user.ProfilePictureUrl,
+                user.CreatedAt,
+                followersCount,
+                followingCount);
+        }
+    }
+}

backend/Core/Musify.Application/Users/IsFollowingUser.cs

@@ -0,0 +1,17 @@
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.Users
+{
+    public record IsFollowingUserQuery(long FollowerId, long FollowedId) : IQuery<bool>;
+
+    public class IsFollowingUserQueryHandler(IDatabase database)
+        : IQueryHandler<IsFollowingUserQuery, bool>
+    {
+        public ValueTask<bool> Handle(IsFollowingUserQuery request, CancellationToken cancellationToken) =>
+            new(database.UserFollows
+                .AsNoTracking()
+                .AnyAsync(f => f.FollowerId == request.FollowerId && f.FollowedId == request.FollowedId, cancellationToken));
+    }
+}

backend/Core/Musify.Application/Users/Responses/UserApplicationResponse.cs

@@ -1,9 +1,11 @@
-using Musify.Domain.Entities;
+using System.Text.Json.Serialization;
+using Musify.Application.Serialization;
+using Musify.Domain.Entities;
 
 namespace Musify.Application.Users.Responses
 {
     public record UserApplicationResponse(
-        long Id,
+        [property: JsonConverter(typeof(LongAsStringConverter))] long Id,
         string Name,
         string? FirstName,
         string? SecondName,

backend/Core/Musify.Application/Users/UnfollowUser.cs

@@ -0,0 +1,32 @@
+using ErrorOr;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.Users
+{
+    public record UnfollowUserCommand(long FollowerId, long FollowedId) : ICommand<ErrorOr<Success>>;
+
+    public class UnfollowUserCommandHandler(
+        IDatabase database,
+        ILogger<UnfollowUserCommandHandler> logger)
+        : ICommandHandler<UnfollowUserCommand, ErrorOr<Success>>
+    {
+        public async ValueTask<ErrorOr<Success>> Handle(UnfollowUserCommand request, CancellationToken cancellationToken)
+        {
+            var follow = await database.UserFollows
+                .SingleOrDefaultAsync(f => f.FollowerId == request.FollowerId && f.FollowedId == request.FollowedId, cancellationToken);
+
+            if (follow is null)
+                return new Success();
+
+            database.UserFollows.Remove(follow);
+            await database.SaveChangesAsync(cancellationToken);
+
+            logger.LogInformation("User {FollowerId} unfollowed user {FollowedId}", request.FollowerId, request.FollowedId);
+
+            return new Success();
+        }
+    }
+}