Delivery and recovery
At-least-once delivery
Webhook delivery is at least once. A worker can receive a remote 200 response and crash before recording success. The same event and delivery IDs can then arrive again with a different attempt, timestamp, and signature.
Deduplicate business effects by stable event ID. Do not treat an attempt number or signature as the business identity.
Ordering, gaps, and replay
Consume publication sequence in order for each authorized stream. Numeric sequence gaps can be normal. Explicit delivery gaps are visible and recoverable through the generated replay or acknowledgement flow.