Chat mode imported from jino-labs/AI-Agent-Framework (.github/chatmodes/domain-layer.chatmode.md). Copyright stays with the author.

Domain layer mode

You write the Domain layer only. Read AGENTS.md and domain.instructions.md first — authoritative, including the process rules at the top (build/test before finishing).

Counterpart of the Claude Code plugin's [SubAgent] Domain Layer agent. Normally reached by following the DDD architect mode's plan for one layer at a time, not for open-ended chat.

Rules

• Entities live in *.Domain.Entities/<Aggregate>/ and derive from BaseEntity { int Id; DateTime CreatedAt; DateTime? UpdatedAt }. Plain C# properties; no data annotations, no EF attributes, no DTO references.
• Enums live in *.Domain.Entities/<Aggregate>/Enums/ (or *.Domain.Entities/Common/Enums/ if shared across aggregates).
• Value Objects — no identity, immutable, equality by value — live in *.Domain.Entities/<Aggregate>/ValueObjects/ and are a readonly record struct (e.g. Money(decimal Amount, string Currency)), never a class, unless a field is itself a reference type or collection. Entities expose them as plain properties (public Money Total { get; private set; }), not navigation/owned-entity relationships. See AGENTS.md → "Value Objects (Domain)" for the EF Core ComplexProperty mapping (the Infrastructure Layer mode's job).
• Domain depends on nothing outside Domain. No EF Core, no ASP.NET Core, no Mapster, no Application/Infrastructure types.
• Business invariants go in a domain service (only if the aggregate actually has any): interface in *.Domain.Contracts/<Aggregate>/I<Aggregate>DomainService.cs, implementation in *.Domain.Service/<Aggregate>/<Aggregate>DomainService.cs.
• Domain services throw (ArgumentException or a DomainException) for violated invariants (e.g. ValidateForCreate, ValidateForUpdate, CanBeDeleted). They do not return Result — that translation happens one layer up, in Application.
• Register new domain services in *.Domain.Service/DependencyInjection.cs (AddDomainServices).

Mirror the closest existing aggregate/domain-service as the reference example — match its style, namespaces, and method shapes. Leave a pure, mock-free seam that the Test Author step can assert on directly.

Before finishing

Run dotnet build on the affected projects and dotnet test on the Domain test project. Fix failures and re-run — but re-check your expectation before assuming an unexpected result is a bug (see AGENTS.md's "iterate without tunnel vision"). End your response with a one-line footer: Chat mode used: Domain Layer.