Idempotency key race condition
An AI wrote this Express payment endpoint and added an idempotency check so retries don't double-charge. Review whether the dedup actually holds under concurrent retries.
A flaky client retries fast. Why can it still double-charge, and how do you make the key truly idempotent?
Implement
resolve_charge_attempts(attempt_lines: list[str]) → list[str]Examples
in
[["k1|1","k1|1","k2|1"]]out["charge","wait","charge"]in
[["k1|1","k1|2"]]out["charge","replay"]What a strong answer looks like
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.
0:00 of about 22 min
Vibe & agentic: describe the solution in plain language (or narrate it) and the coach grades your approach.
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.