refactor: replace Ardalis.Result with ErrorOr across the app

Ardalis Result<T> carried incoherent success sub-statuses and a clunky
generic converter; ErrorOr models success-or-errors cleanly.

- Application: all commands/queries/handlers now return ErrorOr<T>
  (non-generic Result -> ErrorOr<Success>); errors via Error.NotFound/
  Conflict/Validation/Unauthorized/Failure; success via value or new Success()
- Drop ResultExtensions.As<>(): error propagation is now just return .Errors
- Rewrite HTTP mapping (ErrorOrHttpExtensions) off Error.Type; success maps
  to 200 (value) or 204 (Success); Created still built in the endpoints
- Endpoints/gateway middleware: !IsSuccess -> IsError
- Swap Ardalis.Result package for ErrorOr 2.1.1 (remove unused ref from Worker)

Build: 0 warnings, 0 errors.

backend/Directory.Packages.props

@@ -5,9 +5,9 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageVersion Include="Ardalis.Result" Version="10.1.0" />
     <PackageVersion Include="AWSSDK.S3" Version="4.0.23.4" />
     <PackageVersion Include="DispatchR.Mediator" Version="2.2.0" />
+    <PackageVersion Include="ErrorOr" Version="2.1.1" />
     <PackageVersion Include="FluentValidation.DependencyInjectionExtensions" Version="12.1.1" />
     <PackageVersion Include="MassTransit" Version="8.5.9" />
     <PackageVersion Include="MassTransit.EntityFrameworkCore" Version="8.5.9" />

backend/Musify.Api/Endpoints/PlayListEndpoints.cs

@@ -119,7 +119,7 @@ public static class PlayListEndpoints
             new CreatePlayListCommand(currentUser.RequiredId, request.Name, request.Description, request.PictureIntentId),
             cancellationToken);
 
-        if (!result.IsSuccess)
+        if (result.IsError)
             return result.ToHttpResult();
 
         return Results.Created($"/playlists/{result.Value.Id}", result.Value);

backend/Musify.Api/Endpoints/TrackEndpoints.cs

@@ -103,7 +103,7 @@ public static class TrackEndpoints
             new CreateTrackCommand(currentUser.RequiredId, request.Title, request.PictureIntentId, request.AudioIntentId),
             cancellationToken);
 
-        if (!result.IsSuccess)
+        if (result.IsError)
             return result.ToHttpResult();
 
         return Results.Created($"/tracks/{result.Value.Id}", result.Value);

backend/Musify.Api/Endpoints/UserEndpoints.cs

@@ -59,7 +59,7 @@ public static class UserEndpoints
             new CreateUserCommand(request.Id, request.Name, request.FirstName, request.SecondName),
             cancellationToken);
 
-        if (!result.IsSuccess)
+        if (result.IsError)
             return result.ToHttpResult();
 
         return Results.Created($"/users/{result.Value.Id}", result.Value);

backend/Musify.Api/Extensions/ErrorOrHttpExtensions.cs

@@ -0,0 +1,38 @@
+using ErrorOr;
+using IResult = Microsoft.AspNetCore.Http.IResult;
+
+namespace Musify.Api.Extensions;
+
+public static class ErrorOrHttpExtensions
+{
+    public static IResult ToHttpResult<T>(this ErrorOr<T> result)
+    {
+        if (result.IsError)
+            return Problem(result.Errors);
+
+        return result.Value is Success
+            ? Results.NoContent()
+            : Results.Ok(result.Value);
+    }
+
+    private static IResult Problem(List<Error> errors)
+    {
+        if (errors.All(e => e.Type == ErrorType.Validation))
+            return Results.ValidationProblem(ToValidationDictionary(errors));
+
+        var error = errors[0];
+        return error.Type switch
+        {
+            ErrorType.NotFound => Results.NotFound(error.Description),
+            ErrorType.Unauthorized => Results.Unauthorized(),
+            ErrorType.Forbidden => Results.StatusCode(StatusCodes.Status403Forbidden),
+            ErrorType.Conflict => Results.Conflict(error.Description),
+            _ => Results.Problem(error.Description)
+        };
+    }
+
+    private static Dictionary<string, string[]> ToValidationDictionary(IEnumerable<Error> errors) =>
+        errors
+            .GroupBy(e => string.IsNullOrEmpty(e.Code) ? "general" : e.Code)
+            .ToDictionary(g => g.Key, g => g.Select(e => e.Description).ToArray());
+}

backend/Musify.Api/Extensions/ResultHttpExtensions.cs

@@ -1,36 +0,0 @@
-using Ardalis.Result;
-using IResult = Microsoft.AspNetCore.Http.IResult;
-
-namespace Musify.Api.Extensions;
-
-public static class ResultHttpExtensions
-{
-    public static IResult ToHttpResult(this Result result) =>
-        result.Status switch
-        {
-            ResultStatus.Ok or ResultStatus.NoContent => Results.NoContent(),
-            ResultStatus.NotFound => Results.NotFound(result.Errors.FirstOrDefault()),
-            ResultStatus.Invalid => Results.ValidationProblem(ToValidationDictionary(result.ValidationErrors)),
-            ResultStatus.Unauthorized => Results.Unauthorized(),
-            ResultStatus.Forbidden => Results.StatusCode(StatusCodes.Status403Forbidden),
-            ResultStatus.Conflict => Results.Conflict(result.Errors.FirstOrDefault()),
-            _ => Results.Problem(string.Join(", ", result.Errors))
-        };
-
-    public static IResult ToHttpResult<T>(this Result<T> result) =>
-        result.Status switch
-        {
-            ResultStatus.Ok => Results.Ok(result.Value),
-            ResultStatus.NotFound => Results.NotFound(result.Errors.FirstOrDefault()),
-            ResultStatus.Invalid => Results.ValidationProblem(ToValidationDictionary(result.ValidationErrors)),
-            ResultStatus.Unauthorized => Results.Unauthorized(),
-            ResultStatus.Forbidden => Results.StatusCode(StatusCodes.Status403Forbidden),
-            ResultStatus.Conflict => Results.Conflict(result.Errors.FirstOrDefault()),
-            _ => Results.Problem(string.Join(", ", result.Errors))
-        };
-
-    private static Dictionary<string, string[]> ToValidationDictionary(IEnumerable<ValidationError> errors) =>
-        errors
-            .GroupBy(e => string.IsNullOrEmpty(e.Identifier) ? "general" : e.Identifier)
-            .ToDictionary(g => g.Key, g => g.Select(e => e.ErrorMessage).ToArray());
-}

backend/Musify.Api/Musify.Api.csproj

@@ -5,7 +5,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Ardalis.Result" />
+    <PackageReference Include="ErrorOr" />
     <PackageReference Include="AWSSDK.S3" />
     <PackageReference Include="FluentValidation.DependencyInjectionExtensions" />
     <PackageReference Include="MassTransit" />

backend/Musify.Application/Extensions/ResultExtensions.cs

@@ -1,25 +0,0 @@
-using Ardalis.Result;
-
-namespace Musify.Application.Extensions;
-
-public static class ResultExtensions
-{
-    public static Result<TOut> As<TIn, TOut>(this Result<TIn> result)
-    {
-        return result.Status switch
-        {
-            ResultStatus.Ok or
-            ResultStatus.Created or
-            ResultStatus.NoContent   => throw new InvalidOperationException($"Cannot convert a successful result ( {result.Status} ) to another type. Use Map or Bind instead."),
-            ResultStatus.NotFound    => Result<TOut>.NotFound(result.Errors.ToArray()),
-            ResultStatus.Forbidden   => Result<TOut>.Forbidden(result.Errors.ToArray()),
-            ResultStatus.Unauthorized => Result<TOut>.Unauthorized(result.Errors.ToArray()),
-            ResultStatus.Invalid     => Result<TOut>.Invalid(result.ValidationErrors.ToArray()),
-            ResultStatus.Conflict    => Result<TOut>.Conflict(result.Errors.ToArray()),
-            ResultStatus.CriticalError => Result<TOut>.CriticalError(result.Errors.ToArray()),
-            ResultStatus.Unavailable => Result<TOut>.Unavailable(result.Errors.ToArray()),
-            ResultStatus.Error       => Result<TOut>.Error(string.Join(";", result.Errors)),
-            _                        => Result<TOut>.Error(string.Join(";", result.Errors))
-        };
-    }
-}

backend/Musify.Application/Musify.Application.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <ItemGroup>
-    <PackageReference Include="Ardalis.Result" />
+    <PackageReference Include="ErrorOr" />
     <PackageReference Include="MassTransit" />
     <PackageReference Include="Mediator.Abstractions" />
     <PackageReference Include="Mediator.SourceGenerator">

backend/Musify.Application/PlayLists/Commands/AddTrackToPlayListCommand.cs

@@ -1,8 +1,8 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 
 namespace Musify.Application.PlayLists.Commands
 {
     public record AddTrackToPlayListCommand(long UserId, Guid PlayListId, Guid TrackId)
-        : ICommand<Result>;
+        : ICommand<ErrorOr<Success>>;
 }

backend/Musify.Application/PlayLists/Commands/CreatePlayListCommand.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.PlayLists.Responses;
 
@@ -9,5 +9,5 @@ namespace Musify.Application.PlayLists.Commands
         string Name,
         string Description,
         Guid? PictureIntentId)
-        : ICommand<Result<PlayListApplicationResponse>>;
+        : ICommand<ErrorOr<PlayListApplicationResponse>>;
 }

backend/Musify.Application/PlayLists/Commands/DeletePlayListCommand.cs

@@ -1,8 +1,8 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 
 namespace Musify.Application.PlayLists.Commands
 {
     public record DeletePlayListCommand(long UserId, Guid PlayListId)
-        : ICommand<Result>;
+        : ICommand<ErrorOr<Success>>;
 }

backend/Musify.Application/PlayLists/Commands/RemoveTrackFromPlayListCommand.cs

@@ -1,8 +1,8 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 
 namespace Musify.Application.PlayLists.Commands
 {
     public record RemoveTrackFromPlayListCommand(long UserId, Guid PlayListId, Guid TrackId)
-        : ICommand<Result>;
+        : ICommand<ErrorOr<Success>>;
 }

backend/Musify.Application/PlayLists/Commands/RequestPlayListPictureUploadCommand.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.PlayLists.Responses;
 
@@ -9,5 +9,5 @@ namespace Musify.Application.PlayLists.Commands
         string FileType,
         string ContentType,
         long? ExpectedSizeBytes = null)
-        : ICommand<Result<PlayListPictureUploadResponse>>;
+        : ICommand<ErrorOr<PlayListPictureUploadResponse>>;
 }

backend/Musify.Application/PlayLists/Commands/UpdatePlayListCommand.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.PlayLists.Responses;
 
@@ -10,5 +10,5 @@ namespace Musify.Application.PlayLists.Commands
         string? NewName,
         string? NewDescription,
         Guid? NewPictureIntentId)
-        : ICommand<Result<PlayListApplicationResponse>>;
+        : ICommand<ErrorOr<PlayListApplicationResponse>>;
 }

backend/Musify.Application/PlayLists/Handlers/AddTrackToPlayListCommandHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -11,22 +11,22 @@ namespace Musify.Application.PlayLists.Handlers
     public class AddTrackToPlayListCommandHandler(
         IDatabase database,
         ILogger<AddTrackToPlayListCommandHandler> logger)
-        : ICommandHandler<AddTrackToPlayListCommand, Result>
+        : ICommandHandler<AddTrackToPlayListCommand, ErrorOr<Success>>
     {
-        public async ValueTask<Result> Handle(AddTrackToPlayListCommand request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<Success>> Handle(AddTrackToPlayListCommand request, CancellationToken cancellationToken)
         {
             var playList = await database.PlayLists
                 .SingleOrDefaultAsync(pl => pl.Id == request.PlayListId, cancellationToken);
             if (playList is null)
             {
                 logger.LogInformation("Playlist {PlayListId} not found", request.PlayListId);
-                return Result.NotFound();
+                return Error.NotFound();
             }
 
             if (playList.UserId != request.UserId)
             {
                 logger.LogWarning("User {UserId} is not the owner of playlist {PlayListId}", request.UserId, request.PlayListId);
-                return Result.Unauthorized();
+                return Error.Unauthorized();
             }
 
             var trackExists = await database.Tracks
@@ -35,7 +35,7 @@ namespace Musify.Application.PlayLists.Handlers
             if (!trackExists)
             {
                 logger.LogInformation("Track {TrackId} not found", request.TrackId);
-                return Result.NotFound($"Track {request.TrackId} not found");
+                return Error.NotFound(description: $"Track {request.TrackId} not found");
             }
 
             var alreadyAdded = await database.PlayListHasTracks
@@ -44,7 +44,7 @@ namespace Musify.Application.PlayLists.Handlers
             if (alreadyAdded)
             {
                 logger.LogInformation("Track {TrackId} already in playlist {PlayListId}", request.TrackId, request.PlayListId);
-                return Result.Conflict("Track is already in the playlist.");
+                return Error.Conflict(description: "Track is already in the playlist.");
             }
 
             var nextPosition = await database.PlayListHasTracks
@@ -64,7 +64,7 @@ namespace Musify.Application.PlayLists.Handlers
             logger.LogInformation("Added track {TrackId} to playlist {PlayListId} at position {Position}",
                 request.TrackId, request.PlayListId, nextPosition);
 
-            return Result.Success();
+            return new Success();
         }
     }
 }

backend/Musify.Application/PlayLists/Handlers/CreatePlayListCommandHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -7,7 +7,6 @@ using Musify.Application.Shared;
 using Musify.Application.Events;
 using Musify.Application.PlayLists.Commands;
 using Musify.Application.PlayLists.Responses;
-using Musify.Application.Extensions;
 using Musify.Application.Services;
 using Musify.Domain.Entities;
 using Musify.Application.Contracts;
@@ -22,9 +21,9 @@ namespace Musify.Application.PlayLists.Handlers
         ApplicationStorageConfiguration storageConfiguration,
         PlayListConfiguration playListConfiguration,
         UploadIntentConfiguration uploadIntentConfiguration)
-        : ICommandHandler<CreatePlayListCommand, Result<PlayListApplicationResponse>>
+        : ICommandHandler<CreatePlayListCommand, ErrorOr<PlayListApplicationResponse>>
     {
-        public async ValueTask<Result<PlayListApplicationResponse>> Handle(CreatePlayListCommand request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<PlayListApplicationResponse>> Handle(CreatePlayListCommand request, CancellationToken cancellationToken)
         {
             var userExists = await database.Users
                 .AsNoTracking()
@@ -32,7 +31,7 @@ namespace Musify.Application.PlayLists.Handlers
             if (!userExists)
             {
                 logger.LogWarning("User {UserId} not found", request.UserId);
-                return Result.NotFound($"User {request.UserId} not found");
+                return Error.NotFound(description: $"User {request.UserId} not found");
             }
 
             UploadIntent? pictureIntent = null;
@@ -43,8 +42,8 @@ namespace Musify.Application.PlayLists.Handlers
                 var validation = await uploadIntentValidator.ValidateAndLoadAsync(
                     uploadIntentConfiguration,
                     request.PictureIntentId.Value, request.UserId, cancellationToken);
-                if (!validation.IsSuccess)
+                if (validation.IsError)
-                    return validation.As<UploadIntent, PlayListApplicationResponse>();
+                    return validation.Errors;
 
                 pictureIntent = validation.Value;
                 originalPictureName = pictureIntent.ObjectName;
@@ -73,8 +72,8 @@ namespace Musify.Application.PlayLists.Handlers
                 var finalPictureKey = playListConfiguration.Routes.BuildOriginalPicturePath(request.UserId, originalPictureName);
                 var publishResult = await PublishCreatePlayListEventAsync(
                     playList.Id, pictureIntent, finalPictureKey, cancellationToken);
-                if (!publishResult.IsSuccess)
+                if (publishResult.IsError)
-                    return publishResult;
+                    return publishResult.Errors;
             }
 
             try
@@ -84,14 +83,14 @@ namespace Musify.Application.PlayLists.Handlers
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to save playlist for user {UserId}", request.UserId);
-                return Result.Error($"Failed to create playlist for user {request.UserId}");
+                return Error.Failure(description: $"Failed to create playlist for user {request.UserId}");
             }
 
             logger.LogInformation("Created playlist {PlayListId} for user {UserId}", playList.Id, request.UserId);
-            return Result.Created(PlayListApplicationResponse.FromEntity(playList));
+            return PlayListApplicationResponse.FromEntity(playList);
         }
 
-        async Task<Result<PlayListApplicationResponse>> PublishCreatePlayListEventAsync(
+        async Task<ErrorOr<Success>> PublishCreatePlayListEventAsync(
             Guid playListId,
             UploadIntent pictureIntent,
             string finalPictureKey,
@@ -119,12 +118,12 @@ namespace Musify.Application.PlayLists.Handlers
                             playListConfiguration.PicturesSizes.LargePictureWidth,
                             playListConfiguration.PicturesSizes.LargePictureHeight)),
                     cancellationToken);
-                return Result.Success();
+                return new Success();
             }
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to publish create playlist event for playlist {PlayListId}", playListId);
-                return Result.Error($"Failed to publish create playlist event for playlist {playListId}");
+                return Error.Failure(description: $"Failed to publish create playlist event for playlist {playListId}");
             }
         }
     }

backend/Musify.Application/PlayLists/Handlers/DeletePlayListCommandHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -13,21 +13,21 @@ namespace Musify.Application.PlayLists.Handlers
         IDatabase database,
         IEventBus eventBus,
         ILogger<DeletePlayListCommandHandler> logger)
-        : ICommandHandler<DeletePlayListCommand, Result>
+        : ICommandHandler<DeletePlayListCommand, ErrorOr<Success>>
     {
-        public async ValueTask<Result> Handle(DeletePlayListCommand request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<Success>> Handle(DeletePlayListCommand request, CancellationToken cancellationToken)
         {
             var playList = await database.PlayLists.SingleOrDefaultAsync(p => p.Id == request.PlayListId, cancellationToken);
             if (playList is null)
             {
                 logger.LogDebug("Playlist {PlayListId} not found", request.PlayListId);
-                return Result.NotFound();
+                return Error.NotFound();
             }
 
             if (playList.UserId != request.UserId)
             {
                 logger.LogWarning("Playlist {PlayListId} does not belong to user {UserId}", request.PlayListId, request.UserId);
-                return Result.Unauthorized();
+                return Error.Unauthorized();
             }
 
             playList.LifeCycleStatus = LifeCycleStatus.Removing;
@@ -41,7 +41,7 @@ namespace Musify.Application.PlayLists.Handlers
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to publish delete playlist event for playlist {PlayListId}", request.PlayListId);
-                return Result.Error($"Failed to delete playlist {request.PlayListId}");
+                return Error.Failure(description: $"Failed to delete playlist {request.PlayListId}");
             }
 
             try
@@ -51,10 +51,10 @@ namespace Musify.Application.PlayLists.Handlers
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to mark playlist {PlayListId} as removing", request.PlayListId);
-                return Result.Error($"Failed to delete playlist {request.PlayListId}");
+                return Error.Failure(description: $"Failed to delete playlist {request.PlayListId}");
             }
 
-            return Result.NoContent();
+            return new Success();
         }
     }
 }

backend/Musify.Application/PlayLists/Handlers/GetPlayListByIdQueryHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Microsoft.EntityFrameworkCore;
 using Musify.Application.PlayLists.Responses;
 using Musify.Application.PlayLists.Queries;
@@ -8,9 +8,9 @@ using Musify.Application.Contracts;
 namespace Musify.Application.PlayLists.Handlers
 {
     public class GetPlayListByIdQueryHandler(IDatabase database)
-        : IQueryHandler<GetPlayListByIdQuery, Result<PlayListApplicationResponse>>
+        : IQueryHandler<GetPlayListByIdQuery, ErrorOr<PlayListApplicationResponse>>
     {
-        public async ValueTask<Result<PlayListApplicationResponse>> Handle(GetPlayListByIdQuery request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<PlayListApplicationResponse>> Handle(GetPlayListByIdQuery request, CancellationToken cancellationToken)
         {
             var playList = await database.PlayLists
                 .AsNoTracking()
@@ -18,9 +18,10 @@ namespace Musify.Application.PlayLists.Handlers
                 .Select(p => PlayListApplicationResponse.FromEntity(p))
                 .SingleOrDefaultAsync(cancellationToken);
 
-            return playList is null
+            if (playList is null)
-                ? Result<PlayListApplicationResponse>.NotFound()
+                return Error.NotFound();
-                : Result.Success(playList);
+
+            return playList;
         }
     }
 }

backend/Musify.Application/PlayLists/Handlers/GetPlayListTracksQueryHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Musify.Application.Contracts;
@@ -10,15 +10,15 @@ using X.PagedList.EF;
 namespace Musify.Application.PlayLists.Handlers
 {
     public class GetPlayListTracksQueryHandler(IDatabase database)
-        : IQueryHandler<GetPlayListTracksQuery, Result<PaginatedResponse<TrackApplicationResponse>> >
+        : IQueryHandler<GetPlayListTracksQuery, ErrorOr<PaginatedResponse<TrackApplicationResponse>> >
     {
-        public async ValueTask<Result<PaginatedResponse<TrackApplicationResponse> >> Handle(GetPlayListTracksQuery request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<PaginatedResponse<TrackApplicationResponse> >> Handle(GetPlayListTracksQuery request, CancellationToken cancellationToken)
         {
             var playListExists = await database.PlayLists
                 .AsNoTracking()
                 .AnyAsync(p => p.Id == request.PlayListId, cancellationToken);
             if (!playListExists)
-                return Result<PaginatedResponse<TrackApplicationResponse>>.NotFound();
+                return Error.NotFound();
 
             var tracksQuery = database.PlayListHasTracks
                 .AsNoTracking()
@@ -32,7 +32,7 @@ namespace Musify.Application.PlayLists.Handlers
                 .Select(plt => TrackApplicationResponse.FromEntity(plt.Track))
                 .ToPagedListAsync(request.PageNumber, request.PageSize, totalCount, cancellationToken);
 
-            return Result.Success(PaginatedResponse<TrackApplicationResponse>.FromPagedList(pagedTracks));
+            return PaginatedResponse<TrackApplicationResponse>.FromPagedList(pagedTracks);
         }
     }
 }

backend/Musify.Application/PlayLists/Handlers/GetPlayListsByUserIdQueryHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Microsoft.EntityFrameworkCore;
 using Musify.Application.Pagination;
 using Musify.Application.PlayLists.Responses;
@@ -10,9 +10,9 @@ using Musify.Application.Contracts;
 namespace Musify.Application.PlayLists.Handlers
 {
     public class GetPlayListsByUserIdQueryHandler(IDatabase database)
-        : IQueryHandler<GetPlayListsByUserIdQuery, Result<PaginatedResponse<PlayListApplicationResponse> > >
+        : IQueryHandler<GetPlayListsByUserIdQuery, ErrorOr<PaginatedResponse<PlayListApplicationResponse> > >
     {
-        public async ValueTask<Result<PaginatedResponse<PlayListApplicationResponse> >> Handle(GetPlayListsByUserIdQuery request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<PaginatedResponse<PlayListApplicationResponse> >> Handle(GetPlayListsByUserIdQuery request, CancellationToken cancellationToken)
         {
             var playListsQuery = database.PlayLists
                 .AsNoTracking()
@@ -31,7 +31,7 @@ namespace Musify.Application.PlayLists.Handlers
                 .Select(p => PlayListApplicationResponse.FromEntity(p))
                 .ToPagedListAsync(request.PageNumber, request.PageSize, totalCount, cancellationToken);
 
-            return Result.Success(PaginatedResponse<PlayListApplicationResponse>.FromPagedList(pagedPlayLists));
+            return PaginatedResponse<PlayListApplicationResponse>.FromPagedList(pagedPlayLists);
         }
     }
 }

backend/Musify.Application/PlayLists/Handlers/GetPlayListsQueryHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Microsoft.EntityFrameworkCore;
 using Musify.Application.Pagination;
 using Musify.Application.PlayLists.Responses;
@@ -10,9 +10,9 @@ using Musify.Application.Contracts;
 namespace Musify.Application.PlayLists.Handlers
 {
     public class GetPlayListsQueryHandler(IDatabase database)
-        : IQueryHandler<GetPlayListsQuery, Result<PaginatedResponse<PlayListApplicationResponse> >>
+        : IQueryHandler<GetPlayListsQuery, ErrorOr<PaginatedResponse<PlayListApplicationResponse> >>
     {
-        public async ValueTask<Result<PaginatedResponse<PlayListApplicationResponse> >> Handle(GetPlayListsQuery request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<PaginatedResponse<PlayListApplicationResponse> >> Handle(GetPlayListsQuery request, CancellationToken cancellationToken)
         {
             var totalCount = await database.PlayLists.CountAsync(cancellationToken);
 
@@ -22,7 +22,7 @@ namespace Musify.Application.PlayLists.Handlers
                 .Select(p => PlayListApplicationResponse.FromEntity(p))
                 .ToPagedListAsync(request.PageNumber, request.PageSize, totalCount, cancellationToken);
 
-            return Result.Success(PaginatedResponse<PlayListApplicationResponse>.FromPagedList(pagedPlayLists));
+            return PaginatedResponse<PlayListApplicationResponse>.FromPagedList(pagedPlayLists);
         }
     }
 }

backend/Musify.Application/PlayLists/Handlers/RemoveTrackFromPlayListCommandHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -10,22 +10,22 @@ namespace Musify.Application.PlayLists.Handlers
     public class RemoveTrackFromPlayListCommandHandler(
         IDatabase database,
         ILogger<RemoveTrackFromPlayListCommandHandler> logger)
-        : ICommandHandler<RemoveTrackFromPlayListCommand, Result>
+        : ICommandHandler<RemoveTrackFromPlayListCommand, ErrorOr<Success>>
     {
-        public async ValueTask<Result> Handle(RemoveTrackFromPlayListCommand request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<Success>> Handle(RemoveTrackFromPlayListCommand request, CancellationToken cancellationToken)
         {
             var playList = await database.PlayLists
                 .SingleOrDefaultAsync(pl => pl.Id == request.PlayListId, cancellationToken);
             if (playList is null)
             {
                 logger.LogInformation("Playlist {PlayListId} not found", request.PlayListId);
-                return Result.NotFound();
+                return Error.NotFound();
             }
 
             if (playList.UserId != request.UserId)
             {
                 logger.LogWarning("User {UserId} is not the owner of playlist {PlayListId}", request.UserId, request.PlayListId);
-                return Result.Unauthorized();
+                return Error.Unauthorized();
             }
 
             var link = await database.PlayListHasTracks
@@ -33,7 +33,7 @@ namespace Musify.Application.PlayLists.Handlers
             if (link is null)
             {
                 logger.LogInformation("Track {TrackId} not in playlist {PlayListId}", request.TrackId, request.PlayListId);
-                return Result.NotFound("Track is not in the playlist.");
+                return Error.NotFound(description: "Track is not in the playlist.");
             }
 
             database.PlayListHasTracks.Remove(link);
@@ -41,7 +41,7 @@ namespace Musify.Application.PlayLists.Handlers
 
             logger.LogInformation("Removed track {TrackId} from playlist {PlayListId}", request.TrackId, request.PlayListId);
 
-            return Result.Success();
+            return new Success();
         }
     }
 }

backend/Musify.Application/PlayLists/Handlers/RequestPlayListPictureUploadCommandHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -20,9 +20,9 @@ namespace Musify.Application.PlayLists.Handlers
         ApplicationStorageConfiguration storageConfiguration,
         PlayListConfiguration playListConfiguration,
         UploadIntentConfiguration uploadIntentConfiguration)
-        : ICommandHandler<RequestPlayListPictureUploadCommand, Result<PlayListPictureUploadResponse>>
+        : ICommandHandler<RequestPlayListPictureUploadCommand, ErrorOr<PlayListPictureUploadResponse>>
     {
-        public async ValueTask<Result<PlayListPictureUploadResponse>> Handle(RequestPlayListPictureUploadCommand request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<PlayListPictureUploadResponse>> Handle(RequestPlayListPictureUploadCommand request, CancellationToken cancellationToken)
         {
             var userExists = await database.Users
                 .AsNoTracking()
@@ -30,7 +30,7 @@ namespace Musify.Application.PlayLists.Handlers
             if (!userExists)
             {
                 logger.LogWarning("User {UserId} not found", request.UserId);
-                return Result.NotFound($"User {request.UserId} not found");
+                return Error.NotFound(description: $"User {request.UserId} not found");
             }
 
             var effectiveSizeBytes = request.ExpectedSizeBytes
@@ -56,10 +56,10 @@ namespace Musify.Application.PlayLists.Handlers
                 var quotaCheck = await uploadIntentValidator.CheckQuotaAsync(
                     uploadIntentConfiguration,
                     request.UserId, effectiveSizeBytes, 1, cancellationToken);
-                if (!quotaCheck.IsSuccess)
+                if (quotaCheck.IsError)
                 {
                     logger.LogWarning("User {UserId} failed upload intent quota check", request.UserId);
-                    return quotaCheck;
+                    return quotaCheck.Errors;
                 }
 
                 var intent = new UploadIntent
@@ -80,19 +80,19 @@ namespace Musify.Application.PlayLists.Handlers
 
                 logger.LogInformation("Issued upload intent {IntentId} for user {UserId} (PlayListPicture, temp key: {Key})", intent.Id, request.UserId, tempKey);
 
-                return Result.Success(new PlayListPictureUploadResponse(
+                return new PlayListPictureUploadResponse(
                     intent.Id,
                     storageConfiguration.Bucket,
                     tempKey,
                     objectName,
                     request.ContentType,
                     uploadIntentConfiguration.UploadUrlExpiresInSeconds,
-                    uploadUrl));
+                    uploadUrl);
             }
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to generate playlist picture upload URL for user {UserId}", request.UserId);
-                return Result.Error("Failed to generate upload URL");
+                return Error.Failure(description: "Failed to generate upload URL");
             }
         }
     }

backend/Musify.Application/PlayLists/Handlers/UpdatePlayListCommandHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -7,7 +7,6 @@ using Musify.Application.Shared;
 using Musify.Application.Events;
 using Musify.Application.PlayLists.Commands;
 using Musify.Application.PlayLists.Responses;
-using Musify.Application.Extensions;
 using Musify.Application.Services;
 using Musify.Domain.Entities;
 using Musify.Application.Contracts;
@@ -22,21 +21,21 @@ namespace Musify.Application.PlayLists.Handlers
         ApplicationStorageConfiguration storageConfiguration,
         PlayListConfiguration playListConfiguration,
         UploadIntentConfiguration uploadIntentConfiguration)
-        : ICommandHandler<UpdatePlayListCommand, Result<PlayListApplicationResponse>>
+        : ICommandHandler<UpdatePlayListCommand, ErrorOr<PlayListApplicationResponse>>
     {
-        public async ValueTask<Result<PlayListApplicationResponse>> Handle(UpdatePlayListCommand request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<PlayListApplicationResponse>> Handle(UpdatePlayListCommand request, CancellationToken cancellationToken)
         {
             var playListEntity = await database.PlayLists.SingleOrDefaultAsync(pl => pl.Id == request.PlayListId, cancellationToken);
             if (playListEntity is null)
             {
                 logger.LogInformation("Playlist {PlayListId} not found", request.PlayListId);
-                return Result.NotFound();
+                return Error.NotFound();
             }
 
             if (playListEntity.UserId != request.UserId)
             {
                 logger.LogWarning("User {UserId} is not the owner of playlist {PlayListId}", request.UserId, request.PlayListId);
-                return Result.Unauthorized();
+                return Error.Unauthorized();
             }
 
             if (request.NewName is not null)
@@ -58,8 +57,8 @@ namespace Musify.Application.PlayLists.Handlers
                 var validation = await uploadIntentValidator.ValidateAndLoadAsync(
                     uploadIntentConfiguration,
                     request.NewPictureIntentId.Value, request.UserId, cancellationToken);
-                if (!validation.IsSuccess)
+                if (validation.IsError)
-                    return validation.As<UploadIntent, PlayListApplicationResponse>();
+                    return validation.Errors;
 
                 pictureIntent = validation.Value;
                 playListEntity.OriginalPictureName = pictureIntent.ObjectName;
@@ -72,8 +71,8 @@ namespace Musify.Application.PlayLists.Handlers
             {
                 var publishResult = await PublishUpdatePlayListPictureSourceEventAsync(
                     playListEntity.Id, pictureIntent, finalPictureKey, cancellationToken);
-                if (!publishResult.IsSuccess)
+                if (publishResult.IsError)
-                    return publishResult;
+                    return publishResult.Errors;
             }
 
             try
@@ -83,14 +82,14 @@ namespace Musify.Application.PlayLists.Handlers
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to update playlist {PlayListId}", playListEntity.Id);
-                return Result.Error($"Failed to update playlist {playListEntity.Id}");
+                return Error.Failure(description: $"Failed to update playlist {playListEntity.Id}");
             }
 
             logger.LogInformation("Updated playlist {PlayListId}", playListEntity.Id);
-            return Result.Success(PlayListApplicationResponse.FromEntity(playListEntity));
+            return PlayListApplicationResponse.FromEntity(playListEntity);
         }
 
-        async Task<Result<PlayListApplicationResponse>> PublishUpdatePlayListPictureSourceEventAsync(
+        async Task<ErrorOr<Success>> PublishUpdatePlayListPictureSourceEventAsync(
             Guid playListId,
             UploadIntent pictureIntent,
             string finalPictureKey,
@@ -118,12 +117,12 @@ namespace Musify.Application.PlayLists.Handlers
                             playListConfiguration.PicturesSizes.LargePictureWidth,
                             playListConfiguration.PicturesSizes.LargePictureHeight)),
                     cancellationToken);
-                return Result.Success();
+                return new Success();
             }
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to publish update playlist picture source event for playlist {PlayListId}", playListId);
-                return Result.Error($"Failed to publish update playlist picture source event for playlist {playListId}");
+                return Error.Failure(description: $"Failed to publish update playlist picture source event for playlist {playListId}");
             }
         }
     }

backend/Musify.Application/PlayLists/Queries/GetPlayListByIdQuery.cs

@@ -1,9 +1,9 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.PlayLists.Responses;
 
 namespace Musify.Application.PlayLists.Queries
 {
     public record GetPlayListByIdQuery(Guid Id)
-        : IQuery<Result<PlayListApplicationResponse>>;
+        : IQuery<ErrorOr<PlayListApplicationResponse>>;
 }

backend/Musify.Application/PlayLists/Queries/GetPlayListTracksQuery.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.Pagination;
 using Musify.Application.Tracks.Responses;
@@ -9,5 +9,5 @@ namespace Musify.Application.PlayLists.Queries
         Guid PlayListId,
         int PageNumber = 1,
         int PageSize = 10)
-        : IQuery<Result<PaginatedResponse<TrackApplicationResponse>>>;
+        : IQuery<ErrorOr<PaginatedResponse<TrackApplicationResponse>>>;
 }

backend/Musify.Application/PlayLists/Queries/GetPlayListsByUserIdQuery.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.Pagination;
 using Musify.Application.PlayLists.Responses;
@@ -10,5 +10,5 @@ namespace Musify.Application.PlayLists.Queries
         string? Name,
         int PageNumber = 1,
         int PageSize = 10)
-        : IQuery<Result<PaginatedResponse<PlayListApplicationResponse>> >;
+        : IQuery<ErrorOr<PaginatedResponse<PlayListApplicationResponse>> >;
 }

backend/Musify.Application/PlayLists/Queries/GetPlayListsQuery.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.Pagination;
 using Musify.Application.PlayLists.Responses;
@@ -6,5 +6,5 @@ using Musify.Application.PlayLists.Responses;
 namespace Musify.Application.PlayLists.Queries
 {
     public record GetPlayListsQuery(int PageNumber = 1, int PageSize = 10)
-        : IQuery<Result<PaginatedResponse<PlayListApplicationResponse>> >;
+        : IQuery<ErrorOr<PaginatedResponse<PlayListApplicationResponse>> >;
 }

backend/Musify.Application/Services/UploadIntentValidator.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Microsoft.EntityFrameworkCore;
 using Musify.Application.Configuration;
 using Musify.Domain.Entities;
@@ -11,7 +11,7 @@ public sealed class UploadIntentValidator(
     IDatabase database,
     IStorageService storageService)
 {
-    public async Task<Result> CheckQuotaAsync(
+    public async Task<ErrorOr<Success>> CheckQuotaAsync(
         UploadIntentConfiguration config,
         long userId,
         long requiredBytes,
@@ -24,16 +24,16 @@ public sealed class UploadIntentValidator(
             .ToListAsync(cancellationToken);
 
         if (activeIntents.Count + requiredIntentCount > config.MaxActiveUploadIntentsPerUser)
-            return Result.Invalid(new ValidationError("Upload intent limit exceeded. Wait for existing uploads to complete or expire."));
+            return Error.Validation(description: "Upload intent limit exceeded. Wait for existing uploads to complete or expire.");
 
         var activeBytes = activeIntents.Sum(i => i.ExpectedSizeBytes ?? config.DefaultExpectedPictureSizeBytes);
         if (activeBytes + requiredBytes > config.MaxActiveUploadBytesPerUser)
-            return Result.Invalid(new ValidationError("Upload byte quota exceeded. Wait for existing uploads to complete or expire."));
+            return Error.Validation(description: "Upload byte quota exceeded. Wait for existing uploads to complete or expire.");
 
-        return Result.Success();
+        return new Success();
     }
 
-    public async Task<Result<UploadIntent>> ValidateAndLoadAsync(
+    public async Task<ErrorOr<UploadIntent>> ValidateAndLoadAsync(
         UploadIntentConfiguration config,
         Guid intentId,
         long userId,
@@ -43,21 +43,21 @@ public sealed class UploadIntentValidator(
             .FirstOrDefaultAsync(i => i.Id == intentId, cancellationToken);
 
         if (intent is null || intent.UserId != userId)
-            return Result.NotFound("Upload intent not found or not accessible.");
+            return Error.NotFound(description: "Upload intent not found or not accessible.");
 
         if (intent.Status == UploadIntentStatus.Consumed)
-            return Result.Conflict("Upload intent has already been consumed.");
+            return Error.Conflict(description: "Upload intent has already been consumed.");
 
         if (intent.Status == UploadIntentStatus.Expired || intent.ExpiresAt < DateTime.UtcNow)
-            return Result.Invalid(new ValidationError("Upload intent has expired."));
+            return Error.Validation(description: "Upload intent has expired.");
 
         var metadata = await storageService.HeadObjectAsync(intent.Bucket, intent.Key, cancellationToken);
         if (metadata is null)
-            return Result.NotFound("Uploaded object not found in storage. Upload the file first.");
+            return Error.NotFound(description: "Uploaded object not found in storage. Upload the file first.");
 
         if (metadata.ContentLength > config.MaxUploadBytes)
-            return Result.Invalid(new ValidationError($"Uploaded file exceeds the maximum allowed size of {config.MaxUploadBytes} bytes."));
+            return Error.Validation(description: $"Uploaded file exceeds the maximum allowed size of {config.MaxUploadBytes} bytes.");
 
-        return Result.Success(intent);
+        return intent;
     }
 }

backend/Musify.Application/Tracks/Commands/CreateTrackCommand.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.Tracks.Responses;
 
@@ -9,5 +9,5 @@ namespace Musify.Application.Tracks.Commands
         string Title,
         Guid PictureIntentId,
         Guid AudioIntentId)
-        : ICommand<Result<TrackApplicationResponse>>;
+        : ICommand<ErrorOr<TrackApplicationResponse>>;
 }

backend/Musify.Application/Tracks/Commands/DeleteTrackCommand.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 
 namespace Musify.Application.Tracks.Commands
@@ -6,5 +6,5 @@ namespace Musify.Application.Tracks.Commands
     public record DeleteTrackCommand(
         long UserId,
         Guid TrackId)
-        : ICommand<Result>;
+        : ICommand<ErrorOr<Success>>;
 }

backend/Musify.Application/Tracks/Commands/RequestTrackUploadUrlsCommand.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.Tracks.Responses;
 
@@ -12,5 +12,5 @@ namespace Musify.Application.Tracks.Commands
         string AudioContentType,
         long? ExpectedPictureSizeBytes = null,
         long? ExpectedAudioSizeBytes = null)
-        : ICommand<Result<TrackUploadUrlsResponse>>;
+        : ICommand<ErrorOr<TrackUploadUrlsResponse>>;
 }

backend/Musify.Application/Tracks/Handlers/CreateTrackCommandHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -7,7 +7,6 @@ using Musify.Application.Shared;
 using Musify.Application.Events;
 using Musify.Application.Tracks.Commands;
 using Musify.Application.Tracks.Responses;
-using Musify.Application.Extensions;
 using Musify.Application.Services;
 using Musify.Domain.Entities;
 using Musify.Domain.ValueObjects;
@@ -23,29 +22,29 @@ namespace Musify.Application.Tracks.Handlers
         ApplicationStorageConfiguration storageConfiguration,
         TrackConfiguration trackConfiguration,
         UploadIntentConfiguration uploadIntentConfiguration)
-        : ICommandHandler<CreateTrackCommand, Result<TrackApplicationResponse>>
+        : ICommandHandler<CreateTrackCommand, ErrorOr<TrackApplicationResponse>>
     {
-        public async ValueTask<Result<TrackApplicationResponse>> Handle(CreateTrackCommand request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<TrackApplicationResponse>> Handle(CreateTrackCommand request, CancellationToken cancellationToken)
         {
             var userExists = await database.Users.AsNoTracking()
                 .AnyAsync(u => u.Id == request.UserId, cancellationToken);
             if (!userExists)
             {
                 logger.LogWarning("User {UserId} not found", request.UserId);
-                return Result.NotFound($"User {request.UserId} not found");
+                return Error.NotFound(description: $"User {request.UserId} not found");
             }
 
             var pictureValidation = await uploadIntentValidator.ValidateAndLoadAsync(
                 uploadIntentConfiguration,
                 request.PictureIntentId, request.UserId, cancellationToken);
-            if (!pictureValidation.IsSuccess)
+            if (pictureValidation.IsError)
-                return pictureValidation.As<UploadIntent, TrackApplicationResponse>();
+                return pictureValidation.Errors;
 
             var audioValidation = await uploadIntentValidator.ValidateAndLoadAsync(
                 uploadIntentConfiguration,
                 request.AudioIntentId, request.UserId, cancellationToken);
-            if (!audioValidation.IsSuccess)
+            if (audioValidation.IsError)
-                return audioValidation.As<UploadIntent, TrackApplicationResponse>();
+                return audioValidation.Errors;
 
             var pictureIntent = pictureValidation.Value;
             var audioIntent = audioValidation.Value;
@@ -105,7 +104,7 @@ namespace Musify.Application.Tracks.Handlers
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to publish create track event for track {TrackId}", trackEntity.Id);
-                return Result.Error($"Failed to create track for {request.Title}");
+                return Error.Failure(description: $"Failed to create track for {request.Title}");
             }
 
             try
@@ -115,10 +114,10 @@ namespace Musify.Application.Tracks.Handlers
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to save track {Title}", request.Title);
-                return Result.Error($"Failed to create track for {request.Title}");
+                return Error.Failure(description: $"Failed to create track for {request.Title}");
             }
 
-            return Result.Created(TrackApplicationResponse.FromEntity(trackEntity));
+            return TrackApplicationResponse.FromEntity(trackEntity);
         }
     }
 }

backend/Musify.Application/Tracks/Handlers/DeleteTrackCommandHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -13,15 +13,15 @@ namespace Musify.Application.Tracks.Handlers
         IDatabase database,
         IEventBus eventBus,
         ILogger<DeleteTrackCommandHandler> logger)
-        : ICommandHandler<DeleteTrackCommand, Result>
+        : ICommandHandler<DeleteTrackCommand, ErrorOr<Success>>
     {
-        public async ValueTask<Result> Handle(DeleteTrackCommand request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<Success>> Handle(DeleteTrackCommand request, CancellationToken cancellationToken)
         {
             var track = await database.Tracks.SingleOrDefaultAsync(t => t.Id == request.TrackId, cancellationToken);
             if (track is null)
             {
                 logger.LogInformation("Track {TrackId} not found", request.TrackId);
-                return Result.NotFound();
+                return Error.NotFound();
             }
 
             var isOwner = await database.UserHasTracks
@@ -30,14 +30,14 @@ namespace Musify.Application.Tracks.Handlers
             if (!isOwner)
             {
                 logger.LogWarning("User {UserId} unauthorized to delete track {TrackId}", request.UserId, request.TrackId);
-                return Result.Unauthorized();
+                return Error.Unauthorized();
             }
 
             if (track.AudioTranscodeProcessingStatus == ProcessingStatus.Processing
                 || track.AudioTranscodeProcessingStatus == ProcessingStatus.Pending)
             {
                 logger.LogWarning("Track {TrackId} is currently being processed and cannot be deleted", request.TrackId);
-                return Result.Conflict("Track is currently being processed and cannot be deleted");
+                return Error.Conflict(description: "Track is currently being processed and cannot be deleted");
             }
 
             track.LifeCycleStatus = LifeCycleStatus.Removing;
@@ -51,7 +51,7 @@ namespace Musify.Application.Tracks.Handlers
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to publish delete track event for track {TrackId}", request.TrackId);
-                return Result.Error($"Failed to delete track {request.TrackId}");
+                return Error.Failure(description: $"Failed to delete track {request.TrackId}");
             }
 
             try
@@ -61,10 +61,10 @@ namespace Musify.Application.Tracks.Handlers
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to mark track {TrackId} as processing before deletion", request.TrackId);
-                return Result.Error($"Failed to delete track {request.TrackId}");
+                return Error.Failure(description: $"Failed to delete track {request.TrackId}");
             }
 
-            return Result.NoContent();
+            return new Success();
         }
     }
 }

backend/Musify.Application/Tracks/Handlers/GetTrackByIdQueryHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Musify.Application.Contracts;
@@ -8,18 +8,19 @@ using Musify.Application.Tracks.Responses;
 namespace Musify.Application.Tracks.Handlers
 {
     public class GetTrackByIdQueryHandler(IDatabase database)
-        : IQueryHandler<GetTrackByIdQuery, Result<TrackApplicationResponse> >
+        : IQueryHandler<GetTrackByIdQuery, ErrorOr<TrackApplicationResponse> >
     {
-        public async ValueTask<Result<TrackApplicationResponse>> Handle(GetTrackByIdQuery request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<TrackApplicationResponse>> Handle(GetTrackByIdQuery request, CancellationToken cancellationToken)
         {
             var track = await database.Tracks.AsNoTracking()
                 .Where(t => t.Id == request.TrackId)
                 .Select(t => TrackApplicationResponse.FromEntity(t))
                 .SingleOrDefaultAsync(cancellationToken);
 
-            return track is null
+            if (track is null)
-                ? Result<TrackApplicationResponse>.NotFound()
+                return Error.NotFound();
-                : Result.Success(track);
+
+            return track;
         }
     }
 }

backend/Musify.Application/Tracks/Handlers/GetTrackStreamQueryHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -16,9 +16,9 @@ namespace Musify.Application.Tracks.Handlers
         TrackConfiguration trackConfiguration,
         StreamGatewayConfiguration streamGatewayConfiguration,
         ILogger<GetTrackStreamQueryHandler> logger)
-        : IQueryHandler<GetTrackStreamQuery, Result<TrackStreamResponse>>
+        : IQueryHandler<GetTrackStreamQuery, ErrorOr<TrackStreamResponse>>
     {
-        public async ValueTask<Result<TrackStreamResponse>> Handle(GetTrackStreamQuery request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<TrackStreamResponse>> Handle(GetTrackStreamQuery request, CancellationToken cancellationToken)
         {
             var track = await database.Tracks.AsNoTracking()
                 .Where(t => t.Id == request.TrackId)
@@ -26,13 +26,13 @@ namespace Musify.Application.Tracks.Handlers
                 .SingleOrDefaultAsync(cancellationToken);
 
             if (track is null)
-                return Result<TrackStreamResponse>.NotFound();
+                return Error.NotFound();
 
             if (string.IsNullOrWhiteSpace(track.AudioFolderName)
                 || track.AudioTranscodeProcessingStatus != ProcessingStatus.Completed)
             {
                 logger.LogInformation("Stream requested for track {TrackId} but audio is not ready", request.TrackId);
-                return Result<TrackStreamResponse>.Conflict("Track audio is not available for streaming yet.");
+                return Error.Conflict(description: "Track audio is not available for streaming yet.");
             }
 
             var folderPath = trackConfiguration.Routes.BuildProcessedAudioPath(track.AudioFolderName);
@@ -48,7 +48,7 @@ namespace Musify.Application.Tracks.Handlers
 
             logger.LogInformation("Issued stream ticket for track {TrackId} to user {UserId}", request.TrackId, request.UserId);
 
-            return Result.Success(new TrackStreamResponse(manifestUrl, ticket.Token, ticket.ExpiresInSeconds));
+            return new TrackStreamResponse(manifestUrl, ticket.Token, ticket.ExpiresInSeconds);
         }
     }
 }

backend/Musify.Application/Tracks/Handlers/GetTracksByUserIdQueryHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Musify.Application.Pagination;
@@ -10,9 +10,9 @@ using Musify.Application.Contracts;
 namespace Musify.Application.Tracks.Handlers
 {
     public class GetTracksByUserIdQueryHandler(IDatabase database)
-        : IQueryHandler<GetTracksByUserIdQuery, Result<PaginatedResponse<TrackApplicationResponse>> >
+        : IQueryHandler<GetTracksByUserIdQuery, ErrorOr<PaginatedResponse<TrackApplicationResponse>> >
     {
-        public async ValueTask<Result<PaginatedResponse<TrackApplicationResponse> >> Handle(GetTracksByUserIdQuery request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<PaginatedResponse<TrackApplicationResponse> >> Handle(GetTracksByUserIdQuery request, CancellationToken cancellationToken)
         {
             var pageNumber = request.PageNumber < 1 ? 1 : request.PageNumber;
             var pageSize = request.PageSize < 1 ? 10 : request.PageSize;
@@ -35,7 +35,7 @@ namespace Musify.Application.Tracks.Handlers
                 .Select(t => TrackApplicationResponse.FromEntity(t.Track))
                 .ToPagedListAsync(pageNumber, pageSize, totalCount, cancellationToken);
 
-            return Result.Success(PaginatedResponse<TrackApplicationResponse>.FromPagedList(pagedTracks));
+            return PaginatedResponse<TrackApplicationResponse>.FromPagedList(pagedTracks);
         }
     }
 }

backend/Musify.Application/Tracks/Handlers/GetTracksQueryHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Musify.Application.Pagination;
@@ -10,9 +10,9 @@ using Musify.Application.Contracts;
 namespace Musify.Application.Tracks.Handlers
 {
     public class GetTracksQueryHandler(IDatabase database)
-        : IQueryHandler<GetTracksQuery, Result<PaginatedResponse<TrackApplicationResponse>> >
+        : IQueryHandler<GetTracksQuery, ErrorOr<PaginatedResponse<TrackApplicationResponse>> >
     {
-        public async ValueTask<Result<PaginatedResponse<TrackApplicationResponse> >> Handle(GetTracksQuery request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<PaginatedResponse<TrackApplicationResponse> >> Handle(GetTracksQuery request, CancellationToken cancellationToken)
         {
             var tracksQuery = database.UserHasTracks
                 .AsNoTracking()
@@ -23,7 +23,7 @@ namespace Musify.Application.Tracks.Handlers
             var totalCount = await tracksQuery.CountAsync(cancellationToken);
             var pagedTracks = await tracksQuery.ToPagedListAsync(request.PageNumber, request.PageSize, totalCount, cancellationToken);
 
-            return Result.Success(PaginatedResponse<TrackApplicationResponse>.FromPagedList(pagedTracks));
+            return PaginatedResponse<TrackApplicationResponse>.FromPagedList(pagedTracks);
         }
     }
 }

backend/Musify.Application/Tracks/Handlers/RequestTrackUploadUrlsCommandHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -20,9 +20,9 @@ namespace Musify.Application.Tracks.Handlers
         ApplicationStorageConfiguration storageConfiguration,
         TrackConfiguration trackConfiguration,
         UploadIntentConfiguration uploadIntentConfiguration)
-        : ICommandHandler<RequestTrackUploadUrlsCommand, Result<TrackUploadUrlsResponse>>
+        : ICommandHandler<RequestTrackUploadUrlsCommand, ErrorOr<TrackUploadUrlsResponse>>
     {
-        public async ValueTask<Result<TrackUploadUrlsResponse>> Handle(RequestTrackUploadUrlsCommand request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<TrackUploadUrlsResponse>> Handle(RequestTrackUploadUrlsCommand request, CancellationToken cancellationToken)
         {
             var userExists = await database.Users
                 .AsNoTracking()
@@ -30,7 +30,7 @@ namespace Musify.Application.Tracks.Handlers
             if (!userExists)
             {
                 logger.LogWarning("User {UserId} not found", request.UserId);
-                return Result.NotFound($"User {request.UserId} not found");
+                return Error.NotFound(description: $"User {request.UserId} not found");
             }
 
             var effectivePictureSize = request.ExpectedPictureSizeBytes
@@ -72,10 +72,10 @@ namespace Musify.Application.Tracks.Handlers
                 var quotaCheck = await uploadIntentValidator.CheckQuotaAsync(
                     uploadIntentConfiguration,
                     request.UserId, effectivePictureSize + effectiveAudioSize, 2, cancellationToken);
-                if (!quotaCheck.IsSuccess)
+                if (quotaCheck.IsError)
                 {
                     logger.LogWarning("User {UserId} failed upload intent quota check", request.UserId);
-                    return quotaCheck;
+                    return quotaCheck.Errors;
                 }
 
                 var pictureIntent = new UploadIntent
@@ -110,7 +110,7 @@ namespace Musify.Application.Tracks.Handlers
                 logger.LogInformation("Issued upload intents {PictureIntentId}/{AudioIntentId} for user {UserId} (TrackPicture/TrackAudio)",
                     pictureIntent.Id, audioIntent.Id, request.UserId);
 
-                return Result.Success(new TrackUploadUrlsResponse(
+                return new TrackUploadUrlsResponse(
                     pictureIntent.Id,
                     audioIntent.Id,
                     storageConfiguration.Bucket,
@@ -122,12 +122,12 @@ namespace Musify.Application.Tracks.Handlers
                     audioObjectName,
                     request.AudioContentType,
                     audioUploadUrl,
-                    uploadIntentConfiguration.UploadUrlExpiresInSeconds));
+                    uploadIntentConfiguration.UploadUrlExpiresInSeconds);
             }
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to generate track upload URLs for user {UserId}", request.UserId);
-                return Result.Error("Failed to generate upload URLs");
+                return Error.Failure(description: "Failed to generate upload URLs");
             }
         }
     }

backend/Musify.Application/Tracks/Queries/GetTrackByIdQuery.cs

@@ -1,9 +1,9 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.Tracks.Responses;
 
 namespace Musify.Application.Tracks.Queries
 {
     public record GetTrackByIdQuery(Guid TrackId)
-        : IQuery<Result<TrackApplicationResponse>>;
+        : IQuery<ErrorOr<TrackApplicationResponse>>;
 }

backend/Musify.Application/Tracks/Queries/GetTrackStreamQuery.cs

@@ -1,9 +1,9 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.Tracks.Responses;
 
 namespace Musify.Application.Tracks.Queries
 {
     public record GetTrackStreamQuery(Guid TrackId, long UserId)
-        : IQuery<Result<TrackStreamResponse>>;
+        : IQuery<ErrorOr<TrackStreamResponse>>;
 }

backend/Musify.Application/Tracks/Queries/GetTracksByUserIdQuery.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.Pagination;
 using Musify.Application.Tracks.Responses;
@@ -10,5 +10,5 @@ namespace Musify.Application.Tracks.Queries
     string? Name = null,
         int PageNumber = 1,
         int PageSize = 10)
-        : IQuery<Result<PaginatedResponse<TrackApplicationResponse> > >;
+        : IQuery<ErrorOr<PaginatedResponse<TrackApplicationResponse> > >;
 }

backend/Musify.Application/Tracks/Queries/GetTracksQuery.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.Pagination;
 using Musify.Application.Tracks.Responses;
@@ -6,5 +6,5 @@ using Musify.Application.Tracks.Responses;
 namespace Musify.Application.Tracks.Queries
 {
     public record GetTracksQuery(int PageNumber = 1, int PageSize = 10)
-        : IQuery<Result<PaginatedResponse<TrackApplicationResponse> >>;
+        : IQuery<ErrorOr<PaginatedResponse<TrackApplicationResponse> >>;
 }

backend/Musify.Application/Users/Commands/CreateUserCommand.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.Users.Responses;
 using Musify.Domain.Entities;
@@ -9,7 +9,7 @@ namespace Musify.Application.Users.Commands
         string Name,
         string? FirstName,
         string? SecondName)
-        : ICommand<Result<UserApplicationResponse>>
+        : ICommand<ErrorOr<UserApplicationResponse>>
     {
         public static User ToEntity(CreateUserCommand command)
         {

backend/Musify.Application/Users/Commands/SyncUserCommand.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 
 namespace Musify.Application.Users.Commands
@@ -9,5 +9,5 @@ namespace Musify.Application.Users.Commands
         string? FirstName,
         string? SecondName,
         string? ProfilePictureUrl)
-        : ICommand<Result>;
+        : ICommand<ErrorOr<Success>>;
 }

backend/Musify.Application/Users/Handlers/CreateUserCommandHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -9,15 +9,15 @@ using Musify.Application.Users.Responses;
 namespace Musify.Application.Users.Handlers
 {
     public class CreateUserCommandHandler(IDatabase database, ILogger<CreateUserCommandHandler> logger)
-        : ICommandHandler<CreateUserCommand, Result<UserApplicationResponse> >
+        : ICommandHandler<CreateUserCommand, ErrorOr<UserApplicationResponse> >
     {
-        public async ValueTask<Result<UserApplicationResponse>> Handle(CreateUserCommand request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<UserApplicationResponse>> Handle(CreateUserCommand request, CancellationToken cancellationToken)
         {
             var userExists = await database.Users.AnyAsync(u => u.Id == request.Id, cancellationToken);
             if (userExists)
             {
                 logger.LogInformation("User {UserId} already exists", request.Id);
-                return Result<UserApplicationResponse>.Conflict($"User {request.Id} already exists");
+                return Error.Conflict(description: $"User {request.Id} already exists");
             }
 
             var newUser = CreateUserCommand.ToEntity(request);
@@ -30,11 +30,11 @@ namespace Musify.Application.Users.Handlers
             catch (Exception exception)
             {
                 logger.LogError(exception, "Failed to create user {UserId}", request.Id);
-                return Result.Error($"Failed to create user {request.Id}");
+                return Error.Failure(description: $"Failed to create user {request.Id}");
             }
 
             logger.LogInformation("Created user {UserId}", newUser.Id);
-            return Result.Created(UserApplicationResponse.FromEntity(newUser));
+            return UserApplicationResponse.FromEntity(newUser);
         }
     }
 }

backend/Musify.Application/Users/Handlers/GetUserByIdQueryHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Musify.Application.Contracts;
@@ -8,9 +8,9 @@ using Musify.Application.Users.Responses;
 namespace Musify.Application.Users.Handlers
 {
     public class GetUserByIdQueryHandler(IDatabase database)
-        : IQueryHandler<GetUserByIdQuery, Result<UserApplicationResponse> >
+        : IQueryHandler<GetUserByIdQuery, ErrorOr<UserApplicationResponse> >
     {
-        public async ValueTask<Result<UserApplicationResponse>> Handle(GetUserByIdQuery request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<UserApplicationResponse>> Handle(GetUserByIdQuery request, CancellationToken cancellationToken)
         {
             var user = await database.Users
                 .AsNoTracking()
@@ -18,9 +18,10 @@ namespace Musify.Application.Users.Handlers
                 .Select(u => UserApplicationResponse.FromEntity(u))
                 .SingleOrDefaultAsync(cancellationToken);
 
-            return user is null
+            if (user is null)
-                ? Result<UserApplicationResponse>.NotFound()
+                return Error.NotFound();
-                : Result.Success(user);
+
+            return user;
         }
     }
 }

backend/Musify.Application/Users/Handlers/GetUsersQueryHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Musify.Application.Pagination;
@@ -10,9 +10,9 @@ using Musify.Application.Contracts;
 namespace Musify.Application.Users.Handlers
 {
     public class GetUsersQueryHandler(IDatabase database)
-        : IQueryHandler<GetUsersQuery, Result<PaginatedResponse<UserApplicationResponse> > >
+        : IQueryHandler<GetUsersQuery, ErrorOr<PaginatedResponse<UserApplicationResponse> > >
     {
-        public async ValueTask<Result<PaginatedResponse<UserApplicationResponse> >> Handle(GetUsersQuery request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<PaginatedResponse<UserApplicationResponse> >> Handle(GetUsersQuery request, CancellationToken cancellationToken)
         {
             var user = database.Users
                 .AsNoTracking()
@@ -29,7 +29,7 @@ namespace Musify.Application.Users.Handlers
                 .Select(u => UserApplicationResponse.FromEntity(u))
                 .ToPagedListAsync(request.PageNumber, request.PageSize, totalCount, cancellationToken);
 
-            return Result.Success(PaginatedResponse<UserApplicationResponse>.FromPagedList(pagedUser));
+            return PaginatedResponse<UserApplicationResponse>.FromPagedList(pagedUser);
         }
     }
 }

backend/Musify.Application/Users/Handlers/SyncUserCommandHandler.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -9,9 +9,9 @@ using Musify.Domain.Entities;
 namespace Musify.Application.Users.Handlers
 {
     public class SyncUserCommandHandler(IDatabase database, ILogger<SyncUserCommandHandler> logger)
-        : ICommandHandler<SyncUserCommand, Result>
+        : ICommandHandler<SyncUserCommand, ErrorOr<Success>>
     {
-        public async ValueTask<Result> Handle(SyncUserCommand request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<Success>> Handle(SyncUserCommand request, CancellationToken cancellationToken)
         {
             var user = await database.Users
                 .SingleOrDefaultAsync(u => u.Id == request.Id, cancellationToken);
@@ -31,7 +31,7 @@ namespace Musify.Application.Users.Handlers
                 await database.SaveChangesAsync(cancellationToken);
                 logger.LogInformation("Provisioned user {UserId}", request.Id);
 
-                return Result.Success();
+                return new Success();
             }
 
             user.Name = request.Name;
@@ -44,7 +44,7 @@ namespace Musify.Application.Users.Handlers
             if (written > 0)
                 logger.LogInformation("Synced profile for user {UserId}", request.Id);
 
-            return Result.Success();
+            return new Success();
         }
     }
 }

backend/Musify.Application/Users/Queries/GetUserByIdQuery.cs

@@ -1,9 +1,9 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.Users.Responses;
 
 namespace Musify.Application.Users.Queries
 {
     public record GetUserByIdQuery(long Id)
-        : IQuery<Result<UserApplicationResponse> >;
+        : IQuery<ErrorOr<UserApplicationResponse> >;
 }

backend/Musify.Application/Users/Queries/GetUsersQuery.cs

@@ -1,4 +1,4 @@
-using Ardalis.Result;
+using ErrorOr;
 using Mediator;
 using Musify.Application.Pagination;
 using Musify.Application.Users.Responses;
@@ -6,5 +6,5 @@ using Musify.Application.Users.Responses;
 namespace Musify.Application.Users.Queries
 {
     public record GetUsersQuery(int PageNumber, int PageSize, string? UsernameSearch = null)
-        : IQuery<Result<PaginatedResponse<UserApplicationResponse> >>;
+        : IQuery<ErrorOr<PaginatedResponse<UserApplicationResponse> >>;
 }

backend/Musify.StreamingGateway/Authentication/TicketValidator.cs

@@ -1,5 +1,5 @@
 using System.Security.Cryptography;
-using Ardalis.Result;
+using ErrorOr;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.JsonWebTokens;
 using Microsoft.IdentityModel.Tokens;
@@ -35,25 +35,25 @@ public sealed class TicketValidator : IDisposable
         };
     }
 
-    public async Task<Result<string>> ValidateTicketAsync(string? token)
+    public async Task<ErrorOr<string>> ValidateTicketAsync(string? token)
     {
         if (string.IsNullOrWhiteSpace(token))
-            return Result.Unauthorized();
+            return Error.Unauthorized();
 
         var result = await _handler.ValidateTokenAsync(token, _validationParameters);
         if (!result.IsValid)
-            return Result.Unauthorized();
+            return Error.Unauthorized();
 
         if (!result.Claims.TryGetValue("prefix", out var claim))
-            return Result.Unauthorized();
+            return Error.Unauthorized();
 
         if (claim is not string prefix)
-            return Result.Unauthorized();
+            return Error.Unauthorized();
 
         if (string.IsNullOrEmpty(prefix))
-            return Result.Unauthorized();
+            return Error.Unauthorized();
 
-        return Result.Success(prefix);
+        return prefix;
     }
 
     public void Dispose() => _rsa.Dispose();

backend/Musify.StreamingGateway/Middleware/TicketValidationMiddleware.cs

@@ -30,7 +30,7 @@ public sealed class TicketValidationMiddleware(
 
         var validation = await ticketValidator.ValidateTicketAsync(token);
 
-        if (!validation.IsSuccess)
+        if (validation.IsError)
         {
             logger.LogWarning("Rejected media request {Path}: missing or invalid ticket", path);
             context.Response.StatusCode = StatusCodes.Status401Unauthorized;

backend/Musify.StreamingGateway/Musify.StreamingGateway.csproj

@@ -5,7 +5,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Ardalis.Result" />
+    <PackageReference Include="ErrorOr" />
     <PackageReference Include="Microsoft.IdentityModel.JsonWebTokens" />
     <PackageReference Include="Yarp.ReverseProxy" />
   </ItemGroup>

backend/Musify.Worker/Musify.Worker.csproj

@@ -5,7 +5,6 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Ardalis.Result" />
     <PackageReference Include="AWSSDK.S3" />
     <PackageReference Include="DispatchR.Mediator" />
     <PackageReference Include="MassTransit" />