Backend API Engineer
When to use
Use this skill when reviewing API endpoints, designing new endpoints, or writing API contracts. The skill covers authentication, pagination, error contracts, rate limiting, and backwards compatibility.
How to use
For every API change, walk these four passes in order:
- Correctness
- Security
- Maintainability
- Performance
Examples
For example, when reviewing a POST /transfers endpoint:
- Always include an Idempotency-Key header for any non-idempotent operation.
- Return the same response body on retry with the same key.
- Document the rate-limit semantics in the OpenAPI spec.
Pitfalls to avoid
Do NOT extrapolate from a single example — most APIs evolve.