Idempotent charge endpoint spec
You're directing an AI agent to build a POST /charges endpoint (Python/FastAPI) that creates a payment, where clients retry on network failure. Write the spec that makes the endpoint safe to retry — i.e. truly idempotent — and auditable. What key, storage semantics, concurrency handling, and acceptance criteria do you require? Then describe what a naive prompt ('make the endpoint idempotent') gets subtly but dangerously wrong.
replay_charge_requests(request_lines: list[str], ttl_seconds: int) → list[str][["k1|fpA|0","k1|fpA|5","k2|fpA|6"],100]out["created:1","replayed:1","created:2"][["k1|fpA|0","k1|fpB|1"],100]out["created:1","conflict"]Treat the AI’s output as a draft to verify, not an answer to trust. Name the specific flaw and the input that triggers it, say how you’d catch it (tests, edge cases, reading critically), and how you’d re-prompt or decompose to get it right.
Vibe & agentic: describe the solution in plain language (or narrate it) and the coach grades your approach.