backend phase 0: foundation, cross-cutting seams & starter cleanup

Remove the Order demo (entity/feature/repo/config/gRPC/proto) and the three
pre-marketplace migrations; regenerate a fresh InitialBaseline migration.

Stand up the REST surface (PingController + System/Ping CQRS) proving the
Mediator -> behaviors -> OperationResult -> ApiResult envelope end to end.

Close wiring gaps: register LoggingBehavior (outermost) and add the built-in
rate limiter (per-IP global + otp/auth/sensitive policies), placed before
authentication.

Add current-user + audit plumbing: ICurrentUser (HttpContext + null impls),
rename BaseEntity audit fields to CreatedAt/ModifiedAt (DateTimeOffset) +
CreatedById/ModifiedById, stamped by a new AuditFieldInterceptor.

Introduce five cross-cutting seams (IDateTimeProvider, IFieldEncryptor,
ICacheService, IObjectStorage, INotificationDispatcher) with in-memory/local
mocks registered via AddCrossCuttingSeams.

Add Baya.Test.Foundation (encryptor, audit interceptor, ping handler) and
update docs, contracts (swagger.v1.json), handoff, report, and mocks registry.

server/src/Core/Baya.Application/Baya.Application.csproj

@@ -10,6 +10,9 @@
     <EmbeddedResource Remove="Common\ValidationBase\**" />
     <None Remove="Common\ValidationBase\**" />
   </ItemGroup>
+  <ItemGroup>
+    <InternalsVisibleTo Include="Baya.Test.Foundation" />
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Baya.Domain\Baya.Domain.csproj" />
     <PackageReference Include="Mediator.SourceGenerator">

server/src/Core/Baya.Application/Contracts/Common/ICacheService.cs

@@ -0,0 +1,21 @@
+#nullable enable
+namespace Baya.Application.Contracts.Common;
+
+/// <summary>
+/// Typed caching seam for read-heavy and reference data. The mock is backed by in-process memory; the
+/// real implementation swaps to Redis while keeping the same key/TTL scheme.
+/// </summary>
+public interface ICacheService
+{
+    ValueTask<T?> GetAsync<T>(string key, CancellationToken cancellationToken = default);
+
+    ValueTask SetAsync<T>(string key, T value, TimeSpan? ttl = null, CancellationToken cancellationToken = default);
+
+    ValueTask RemoveAsync(string key, CancellationToken cancellationToken = default);
+
+    ValueTask<T> GetOrCreateAsync<T>(
+        string key,
+        Func<CancellationToken, ValueTask<T>> factory,
+        TimeSpan? ttl = null,
+        CancellationToken cancellationToken = default);
+}

server/src/Core/Baya.Application/Contracts/Common/ICurrentUser.cs

@@ -0,0 +1,15 @@
+namespace Baya.Application.Contracts.Common;
+
+/// <summary>
+/// Ambient accessor for the authenticated caller, wrapping the HTTP context behind an Application
+/// contract. Registered Scoped. A null-object implementation serves non-HTTP contexts (jobs, tests)
+/// so the audit interceptor and handlers never depend on <c>IHttpContextAccessor</c> directly.
+/// </summary>
+public interface ICurrentUser
+{
+    int? UserId { get; }
+
+    bool IsAuthenticated { get; }
+
+    IReadOnlyList<string> Roles { get; }
+}

server/src/Core/Baya.Application/Contracts/Common/IDateTimeProvider.cs

@@ -0,0 +1,10 @@
+namespace Baya.Application.Contracts.Common;
+
+/// <summary>
+/// Abstracts the system clock so handlers and the audit interceptor never call <c>DateTime.Now</c>
+/// directly and time can be frozen in tests.
+/// </summary>
+public interface IDateTimeProvider
+{
+    DateTimeOffset UtcNow { get; }
+}

server/src/Core/Baya.Application/Contracts/Common/IFieldEncryptor.cs

@@ -0,0 +1,20 @@
+namespace Baya.Application.Contracts.Common;
+
+/// <summary>
+/// Seam for field-level PII encryption (phone, national id, IBAN, addresses, clinical notes).
+/// Every encrypted-at-rest column flows through this. The mock uses a local symmetric key; the real
+/// implementation swaps to a KMS / column-encryption / Key Vault provider without touching callers.
+/// Implementations must never log or surface plaintext.
+/// </summary>
+public interface IFieldEncryptor
+{
+    string Encrypt(string plaintext);
+
+    string Decrypt(string ciphertext);
+
+    /// <summary>
+    /// Deterministic keyed hash for equality lookups on encrypted columns (e.g. <c>iban_hash</c>) —
+    /// the same input always yields the same hash so it can be indexed and queried.
+    /// </summary>
+    string Hash(string value);
+}

server/src/Core/Baya.Application/Contracts/Common/INotificationDispatcher.cs

@@ -0,0 +1,32 @@
+namespace Baya.Application.Contracts.Common;
+
+/// <summary>
+/// The channel a notification is delivered through. Only <see cref="InApp"/> is wired now; SMS/push
+/// arrive in later phases behind the same seam.
+/// </summary>
+public enum NotificationChannel
+{
+    InApp,
+    Sms,
+    Push
+}
+
+/// <summary>A notification to dispatch to a recipient over one channel.</summary>
+/// <param name="RecipientUserId">The target user.</param>
+/// <param name="Channel">Delivery channel.</param>
+/// <param name="Title">Short title/subject.</param>
+/// <param name="Body">Message body (no secrets/PII in logs).</param>
+public sealed record Notification(
+    int RecipientUserId,
+    NotificationChannel Channel,
+    string Title,
+    string Body);
+
+/// <summary>
+/// Seam for emitting notifications from domains like booking and payments. The mock logs/no-ops; the
+/// real in-app write lands in backend-phase-15, with SMS/push added behind the same interface.
+/// </summary>
+public interface INotificationDispatcher
+{
+    ValueTask DispatchAsync(Notification notification, CancellationToken cancellationToken = default);
+}

server/src/Core/Baya.Application/Contracts/Common/IObjectStorage.cs

@@ -0,0 +1,22 @@
+#nullable enable
+namespace Baya.Application.Contracts.Common;
+
+/// <summary>
+/// Blob/object storage seam keyed by an opaque storage key. The mock stores blobs on local disk; the
+/// real implementation swaps to MinIO/S3/ArvanCloud (presigned URLs) without changing callers.
+/// </summary>
+public interface IObjectStorage
+{
+    ValueTask PutAsync(
+        string key,
+        Stream content,
+        string contentType,
+        CancellationToken cancellationToken = default);
+
+    ValueTask<Stream?> GetAsync(string key, CancellationToken cancellationToken = default);
+
+    ValueTask DeleteAsync(string key, CancellationToken cancellationToken = default);
+
+    /// <summary>A retrievable URL for the stored object (presigned by the real provider).</summary>
+    string GetUrl(string key);
+}

server/src/Core/Baya.Application/Contracts/Persistence/IOrderRepository.cs

@@ -1,12 +0,0 @@
-using Baya.Domain.Entities.Order;
-
-namespace Baya.Application.Contracts.Persistence;
-
-public interface IOrderRepository
-{
-    Task AddOrderAsync(Order order);
-    Task<List<Order>> GetAllUserOrdersAsync(int userId);
-    Task<List<Order>> GetAllOrdersWithRelatedUserAsync();
-    Task<Order> GetUserOrderByIdAndUserIdAsync(int userId,int orderId,bool trackEntity);
-    Task DeleteUserOrdersAsync(int userId);
-}

server/src/Core/Baya.Application/Contracts/Persistence/IUnitOfWork.cs

@@ -3,7 +3,6 @@
 public interface IUnitOfWork
 {
     public IUserRefreshTokenRepository UserRefreshTokenRepository { get; }
-    public IOrderRepository OrderRepository { get; }
     Task CommitAsync();
     ValueTask RollBackAsync();
 }

server/src/Core/Baya.Application/Features/Order/Commands/AddOrderCommand.Handler.cs

@@ -1,25 +0,0 @@
-using Baya.Application.Contracts.Identity;
-using Baya.Application.Contracts.Persistence;
-using Baya.Application.Models.Common;
-using Mediator;
-
-namespace Baya.Application.Features.Order.Commands;
-
-internal class AddOrderCommandHandler(IUnitOfWork unitOfWork, IAppUserManager userManager)
-    : IRequestHandler<AddOrderCommand, OperationResult<bool>>
-{
-    public async ValueTask<OperationResult<bool>> Handle(AddOrderCommand request, CancellationToken cancellationToken)
-    {
-        var user = await userManager.GetUserByIdAsync(request.UserId);
-
-        if(user==null)
-            return OperationResult<bool>.FailureResult("User Not Found");
-
-        await unitOfWork.OrderRepository.AddOrderAsync(new Domain.Entities.Order.Order()
-            { UserId = user.Id, OrderName = request.OrderName });
-
-        await unitOfWork.CommitAsync();
-
-        return OperationResult<bool>.SuccessResult(true);
-    }
-}

server/src/Core/Baya.Application/Features/Order/Commands/AddOrderCommand.cs

@@ -1,25 +0,0 @@
-using System.Text.Json.Serialization;
-using Baya.Application.Models.Common;
-using Baya.SharedKernel.ValidationBase;
-using Baya.SharedKernel.ValidationBase.Contracts;
-using FluentValidation;
-using Mediator;
-
-namespace Baya.Application.Features.Order.Commands;
-
-public record AddOrderCommand( string OrderName) : IRequest<OperationResult<bool>>,
-    IValidatableModel<AddOrderCommand>
-{
-    [JsonIgnore]
-    public int UserId { get; set; }
-
-    public IValidator<AddOrderCommand> ValidateApplicationModel(ApplicationBaseValidationModelProvider<AddOrderCommand> validator)
-    {
-        validator.RuleFor(c => c.OrderName)
-            .NotEmpty()
-            .NotNull()
-            .WithMessage("Please enter your role name");
-
-        return validator;
-    }
-}

server/src/Core/Baya.Application/Features/Order/Commands/DeleteUserOrdersCommand.Handler.cs

@@ -1,15 +0,0 @@
-using Baya.Application.Contracts.Persistence;
-using Baya.Application.Models.Common;
-using Mediator;
-
-namespace Baya.Application.Features.Order.Commands;
-
-public class DeleteUserOrdersCommandHandler(IUnitOfWork unitOfWork) : IRequestHandler<DeleteUserOrdersCommand,OperationResult<bool>>
-{
-    public async ValueTask<OperationResult<bool>> Handle(DeleteUserOrdersCommand request, CancellationToken cancellationToken)
-    {
-        await unitOfWork.OrderRepository.DeleteUserOrdersAsync(request.UserId);
-
-        return OperationResult<bool>.SuccessResult(true);
-    }
-}

server/src/Core/Baya.Application/Features/Order/Commands/DeleteUserOrdersCommand.cs

@@ -1,6 +0,0 @@
-using Baya.Application.Models.Common;
-using Mediator;
-
-namespace Baya.Application.Features.Order.Commands;
-
-public record DeleteUserOrdersCommand(int UserId):IRequest<OperationResult<bool>>;

server/src/Core/Baya.Application/Features/Order/Commands/UpdateUserOrderCommand.Handler.cs

@@ -1,25 +0,0 @@
-using Baya.Application.Contracts.Persistence;
-using Baya.Application.Models.Common;
-using Mediator;
-
-namespace Baya.Application.Features.Order.Commands;
-
-public class UpdateUserOrderCommandHandler(IUnitOfWork unitOfWork) : IRequestHandler<UpdateUserOrderCommand,OperationResult<bool>>
-{
-
-
-    public async ValueTask<OperationResult<bool>> Handle(UpdateUserOrderCommand request, CancellationToken cancellationToken)
-    {
-        var order = await unitOfWork.OrderRepository.GetUserOrderByIdAndUserIdAsync(request.UserId, request.OrderId,
-            true);
-
-        if(order is null)
-            return OperationResult<bool>.NotFoundResult("Specified Order not found");
-
-        order.OrderName=request.OrderName;
-
-        await unitOfWork.CommitAsync();
-
-        return OperationResult<bool>.SuccessResult(true);
-    }
-}

server/src/Core/Baya.Application/Features/Order/Commands/UpdateUserOrderCommand.cs

@@ -1,23 +0,0 @@
-using System.Text.Json.Serialization;
-using Baya.Application.Models.Common;
-using Baya.SharedKernel.ValidationBase;
-using Baya.SharedKernel.ValidationBase.Contracts;
-using FluentValidation;
-using Mediator;
-
-namespace Baya.Application.Features.Order.Commands;
-
-public record UpdateUserOrderCommand
-    (int OrderId, string OrderName) : IRequest<OperationResult<bool>>,IValidatableModel<UpdateUserOrderCommand>
-{
-    [JsonIgnore]
-    public int UserId { get; set; }
-
-    public IValidator<UpdateUserOrderCommand> ValidateApplicationModel(ApplicationBaseValidationModelProvider<UpdateUserOrderCommand> validator)
-    {
-        validator.RuleFor(c => c.OrderId).NotEmpty().GreaterThan(0);
-        validator.RuleFor(c => c.OrderName).NotEmpty().NotNull();
-
-        return validator;
-    }
-};

server/src/Core/Baya.Application/Features/Order/Queries/GetAllOrders/GetAllOrdersQuery.cs

@@ -1,6 +0,0 @@
-using Baya.Application.Models.Common;
-using Mediator;
-
-namespace Baya.Application.Features.Order.Queries.GetAllOrders;
-
-public record GetAllOrdersQuery():IRequest<OperationResult<List<GetAllOrdersQueryResult>>>;

server/src/Core/Baya.Application/Features/Order/Queries/GetAllOrders/GetAllOrdersQueryHandler.cs

@@ -1,20 +0,0 @@
-using Baya.Application.Contracts.Persistence;
-using Baya.Application.Models.Common;
-using MapsterMapper;
-using Mediator;
-
-namespace Baya.Application.Features.Order.Queries.GetAllOrders
-{
-    internal class GetAllOrdersQueryHandler(IUnitOfWork unitOfWork, IMapper mapper)
-        : IRequestHandler<GetAllOrdersQuery, OperationResult<List<GetAllOrdersQueryResult>>>
-    {
-        public async ValueTask<OperationResult<List<GetAllOrdersQueryResult>>> Handle(GetAllOrdersQuery request, CancellationToken cancellationToken)
-        {
-            var orders = await unitOfWork.OrderRepository.GetAllOrdersWithRelatedUserAsync();
-
-            var result = orders.Select(mapper.Map<Domain.Entities.Order.Order,GetAllOrdersQueryResult>).ToList();
-
-            return OperationResult<List<GetAllOrdersQueryResult>>.SuccessResult(result);
-        }
-    }
-}

server/src/Core/Baya.Application/Features/Order/Queries/GetAllOrders/GetAllOrdersQueryResult.cs

@@ -1,19 +0,0 @@
-
-
-using Mapster;
-
-namespace Baya.Application.Features.Order.Queries.GetAllOrders;
-
-public record GetAllOrdersQueryResult(int OrderId, string OrderName, int OrderOwnerId, string OrderOwnerUserName);
-
-class GetAllOrdersQueryResultMapping : IRegister
-{
-    public void Register(TypeAdapterConfig config)
-    {
-        config.NewConfig<Domain.Entities.Order.Order, GetAllOrdersQueryResult>()
-            .Map(dest => dest.OrderId, src => src.Id)
-            .Map(dest => dest.OrderName, src => src.OrderName)
-            .Map(dest => dest.OrderOwnerId, src => src.User.Id)
-            .Map(dest => dest.OrderOwnerUserName, src => src.User.UserName);
-    }
-}

server/src/Core/Baya.Application/Features/Order/Queries/GetUserOrders/GetUserOrdersQueryHandler.cs

@@ -1,21 +0,0 @@
-using Baya.Application.Contracts.Persistence;
-using Baya.Application.Models.Common;
-using Mediator;
-
-namespace Baya.Application.Features.Order.Queries.GetUserOrders;
-
-internal class GetUserOrdersQueryHandler(IUnitOfWork unitOfWork)
-    : IRequestHandler<GetUserOrdersQueryModel, OperationResult<List<GetUsersQueryResultModel>>>
-{
-    public async ValueTask<OperationResult<List<GetUsersQueryResultModel>>> Handle(GetUserOrdersQueryModel request, CancellationToken cancellationToken)
-    {
-        var orders = await unitOfWork.OrderRepository.GetAllUserOrdersAsync(request.UserId);
-
-        if(!orders.Any())
-            return OperationResult<List<GetUsersQueryResultModel>>.NotFoundResult("You Don't Have Any Orders");
-
-        var result = orders.Select(c => new GetUsersQueryResultModel(c.Id, c.OrderName));
-
-        return OperationResult<List<GetUsersQueryResultModel>>.SuccessResult(result.ToList());
-    }
-}

server/src/Core/Baya.Application/Features/Order/Queries/GetUserOrders/GetUserOrdersQueryModel.cs

@@ -1,6 +0,0 @@
-using Baya.Application.Models.Common;
-using Mediator;
-
-namespace Baya.Application.Features.Order.Queries.GetUserOrders;
-
-public record GetUserOrdersQueryModel(int UserId) : IRequest<OperationResult<List<GetUsersQueryResultModel>>>;

server/src/Core/Baya.Application/Features/Order/Queries/GetUserOrders/GetUsersQueryResultModel.cs

@@ -1,3 +0,0 @@
-namespace Baya.Application.Features.Order.Queries.GetUserOrders;
-
-public record GetUsersQueryResultModel(int OrderId, string OrderName);

server/src/Core/Baya.Application/Features/System/Queries/Ping/PingQuery.Handler.cs

@@ -0,0 +1,16 @@
+using Baya.Application.Contracts.Common;
+using Baya.Application.Models.Common;
+using Mediator;
+
+namespace Baya.Application.Features.System.Queries.Ping;
+
+internal sealed class PingQueryHandler(IDateTimeProvider dateTimeProvider)
+    : IRequestHandler<PingQuery, OperationResult<PingQueryResult>>
+{
+    public ValueTask<OperationResult<PingQueryResult>> Handle(PingQuery request, CancellationToken cancellationToken)
+    {
+        var result = new PingQueryResult("Baya.Web.Api", "ok", dateTimeProvider.UtcNow);
+
+        return ValueTask.FromResult(OperationResult<PingQueryResult>.SuccessResult(result));
+    }
+}

server/src/Core/Baya.Application/Features/System/Queries/Ping/PingQuery.Result.cs

@@ -0,0 +1,4 @@
+namespace Baya.Application.Features.System.Queries.Ping;
+
+/// <summary>Liveness payload proving the REST → Mediator → envelope pipeline end-to-end.</summary>
+public record PingQueryResult(string Service, string Status, DateTimeOffset ServerTimeUtc);

server/src/Core/Baya.Application/Features/System/Queries/Ping/PingQuery.cs

@@ -0,0 +1,6 @@
+using Baya.Application.Models.Common;
+using Mediator;
+
+namespace Baya.Application.Features.System.Queries.Ping;
+
+public record PingQuery : IRequest<OperationResult<PingQueryResult>>;

server/src/Core/Baya.Application/ServiceConfiguration/ServiceCollectionExtension.cs

@@ -16,8 +16,10 @@ public static class ServiceCollectionExtension
             options.Namespace = "Baya.Application.Mediator";
         });
 
+        services.AddScoped(typeof(IPipelineBehavior<,>), typeof(LoggingBehavior<,>));
+
         services.AddScoped(typeof(IPipelineBehavior<,>), typeof(MetricsBehaviour<,>));
-        
+
         services.AddScoped(typeof(IPipelineBehavior<,>), typeof(ValidateCommandBehavior<,>));
         
 

server/src/Core/Baya.Domain/Common/BaseEntity.cs

@@ -1,4 +1,4 @@
-namespace Baya.Domain.Common;
+namespace Baya.Domain.Common;
 
 public interface IEntity
 {
@@ -6,11 +6,21 @@ public interface IEntity
 
 public interface ITimeModification
 {
-    DateTime CreatedTime { get; set; }
-    DateTime? ModifiedDate { get; set; }
+    DateTimeOffset CreatedAt { get; set; }
+    DateTimeOffset? ModifiedAt { get; set; }
 }
 
-public abstract class BaseEntity<TKey> : IEntity, ITimeModification
+/// <summary>
+/// An entity whose create/modify timestamps and the acting user are stamped automatically by the
+/// SaveChanges audit interceptor — handlers must never set these fields themselves.
+/// </summary>
+public interface IAuditableEntity : ITimeModification
+{
+    int? CreatedById { get; set; }
+    int? ModifiedById { get; set; }
+}
+
+public abstract class BaseEntity<TKey> : IEntity, IAuditableEntity
 {
     public TKey Id { get; protected set; }
 
@@ -49,11 +59,13 @@ public abstract class BaseEntity<TKey> : IEntity, ITimeModification
         return (GetType().ToString() + Id).GetHashCode();
     }
 
-    public DateTime CreatedTime { get; set; }
-    public DateTime? ModifiedDate { get; set; }
+    public DateTimeOffset CreatedAt { get; set; }
+    public DateTimeOffset? ModifiedAt { get; set; }
+    public int? CreatedById { get; set; }
+    public int? ModifiedById { get; set; }
 }
 
 public abstract class BaseEntity : BaseEntity<int>
 {
 
-}
+}

server/src/Core/Baya.Domain/Entities/Order/Order.cs

@@ -1,16 +0,0 @@
-using Baya.Domain.Common;
-
-namespace Baya.Domain.Entities.Order;
-
-public class Order:BaseEntity
-{
-    public string OrderName { get; set; }
-    public bool IsDeleted { get; set; }
-
-    #region Navigation Properties
-
-    public User.User User { get; set; }
-    public int UserId { get; set; }
-
-    #endregion
-}

server/src/Core/Baya.Domain/Entities/User/User.cs

@@ -19,11 +19,4 @@ public class User:IdentityUser<int>,IEntity
     public ICollection<UserClaim> Claims { get; set; }
     public ICollection<UserToken> Tokens { get; set; }
     public ICollection<UserRefreshToken> UserRefreshTokens { get; set; }
-
-    #region Navigation Properties
-
-    public IList<Order.Order> Orders { get; set; }
-
-    #endregion
-
 }

server/src/Core/Baya.Domain/Entities/User/UserRefreshToken.cs

@@ -1,16 +1,10 @@
-using Baya.Domain.Common;
+using Baya.Domain.Common;
 
 namespace Baya.Domain.Entities.User;
 
 public class UserRefreshToken:BaseEntity<Guid>
 {
-    public UserRefreshToken()
-    {
-        CreatedAt=DateTime.Now;
-    }
-
     public int UserId { get; set; }
     public User User { get; set; }
-    public DateTime CreatedAt { get; set; }
     public bool IsValid { get; set; }
-}
+}