Question
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.
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 coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.