middleware-design Skill

Goal

This skill guides the creation of the request processing pipeline ("The Onion Architecture").

Steps

1. The Standard Pipeline (Order Matters)

1. Request ID: Generate trace_id immediately. (Before logs).
2. CORS: Allow/Block origins. (Before processing).
3. Body Parser: JSON/Form parsing. (Limit size to prevent DoS).
4. Rate Limiter: Token Bucket algorithm. (Stop abuse cheaply).
5. Authentication: Verify JWT/Session. (Who is it?).
6. Authorization: Check Roles/Scopes. (Can they do it?).
7. Validation: Zod/Pydantic schema check. (Is input valid?).
8. Controller: Business Logic.
9. Error Handler: Catch exceptions, format JSON, scrub sensitive data.