devarch-module

Backend Pattern (MediatR CQRS / IResult / AOP)

Trigger phrases: "devarch-module", "new handler", "write a command", "add a query", "validator", "aspect"

This is the DEFAULT backend pattern, not the only one. backend-expert-csk is pattern-neutral; it applies whichever backend-pattern skill the project ships. A project on Clean Architecture, Vertical Slice, Minimal API, or plain layered replaces this skill with its own (same format) — the agent then follows that. Nothing forces DevArch.

Kit adaptation (local, .claude/): backend-expert-csk applies the devarch-module skill. Sources (alignment): the DevArchitecture pattern — its name does NOT leak into generated code / namespace / file / comment / csproj / Swagger / JWT (§4.2). The pattern lives here; the generated artifact is written with project-specific names.

Layout

Three folders under Business/Handlers/{Entity}/: Commands/ · Queries/ · ValidationRules/. Each request + its handler lives in a single file, nested.

Command pattern (write)

• Request class: IRequest<IResult> (or IRequest<IDataResult<T>> if it returns data).
• Handler: IRequestHandler<TRequest, IResult> inside the outer class; dependencies via the ctor (repository, cache, mediator).
• Body: write via the repository → SaveChangesAsync() → clear the relevant cache key → return new SuccessResult(Messages.Added).

Query pattern (read)

• Request: IRequest<IDataResult<IEnumerable<TDto>>> / IDataResult<TDto>.
• The handler fetches the data via the repository/DTO → return new SuccessDataResult<...>(data).

Result contract (NO bare types)

• Success: SuccessResult(message) / SuccessDataResult<T>(data, message?).
• Error: ErrorResult(message) / ErrorDataResult<T>(message).
• The handler never returns a raw T / void; always IResult/IDataResult<T>.