api-backend-developmentlisted

# CIEL ADAPTATION: API & Backend Development (Server-Side) This skill formalizes the development of scalable, maintainable server-side systems. it enforces resource-based REST design and a strict layered architecture. ## API Design Mandates 1. **Resource Naming**: Use plural nouns, lowercase, kebab-case (e.g., `/api/v1/team-members`). 2. **Semantic Status Codes**: - `201 Created`: For successful POSTs. - `422 Unprocessable Entity`: For semantically invalid data (Zod/Pydantic errors). - `500`: Never leak details (stack traces/SQL) to the client. 3. **Pagination**: Default to Cursor-Based for large datasets; Offset-Based for admin/search. ## Layered Architecture (The 3-Layer Pattern) - **Controller/Handler**: Request validation and response mapping. No business logic. - **Service Layer**: Pure business orchestration. Coordinates between repositories and external APIs. - **Repository**: Abstract data access. Maps DB rows to Domain Models. ## Performance & Optimization - **N+1 Prevention**: Always batch fetch relationships using `IN` queries or Joins. - **Select Specifics**: Never `SELECT *`. Only retrieve required columns. - **Fail Gracefully**: Implement exponential backoff for all external API calls. ## Anti-Patterns - **Verb-in-URL**: Using `/api/getUsers` instead of `GET /api/users`. - **Impossible States**: Using boolean flag soup instead of a single `status` enum. - **Direct DB Leaks**: Returning raw ORM/DB objects directly in the API response.