Sume webhooks: return 2xx only after you store the event

After you store the event durably, return any 2xx. Sume retries network errors and non-2xx responses until all attempts are used, and you should use job_id as your idempotency key (read 2026-10-06 in the webhook docs).

What does that look like?

Write the event to your own storage keyed by job_id, then respond. A second delivery of the same job then becomes a no-op.

seen: set[str] = set()

def handle(event: dict) -> int:
    job_id = event["job_id"]
    if job_id in seen:
        return 200
    seen.add(job_id)
    return 200

print(handle({"job_id": "job_1"}), handle({"job_id": "job_1"}))

What should I do in practice?

A slow endpoint spends the retry budget.

• Keep the receiver under the 10 s timeout.
• Do heavy work after you ack.
• Use a database, not a set, in production.