FATAL for the prompt: uses aiohttp (external dep) despite 'stdlib only' requirement. ModuleNotFoundError on import — won't run as delivered.
Chose aiohttp reasoning that stdlib http.server is synchronous/blocks the loop — a fair architectural point, but it violated the explicit constraint instead of using asyncio.start_server (stdlib, async) like Qwen did.
Wrapped in markdown + prose preamble (needed extraction).
▮ RECOMMENDED USE
Violated the stdlib-only constraint: used aiohttp (2 imports) for the HTTP server, so it won't run as-is. Weaker than Qwen's 75 on the same prompt (Qwen used stdlib and passed). Not the offload pick for webhook work; Qwen is.
▮ REFACTORED PATCH
# FIX: replace aiohttp server with asyncio.start_server (stdlib, fully async) — exactly
# what the Qwen webhook submission did. Then the logic (rate limit/idempotency/429) can run.