Designing an HTTP API (REST, Done Right)

Most "REST" APIs are RPC in disguise. This quiz sharpens the decisions that matter when other people build against your endpoints: method safety and idempotency, PUT/PATCH/POST, idempotency keys, cursor vs. offset pagination, the real meaning of 409/412/422/429, versioning, and error envelopes a client can program against. Every answer is grounded in the HTTP specs (RFC 9110, RFC 5789, RFC 9457).