Payment Failure Lab: Webhooks, Idempotency, and Retries

This workshop uses a fake checkout flow, a webhook receiver, and a queue of messy events: duplicates, delays, missing signatures, customer refreshes, and partial failures. The challenge is to keep the order state correct without trusting any single request too much.

Participants will design idempotency keys, verify webhook signatures, log decision points, and write retry rules that avoid double charging or silently dropping orders. The session is useful for anyone building commerce, subscriptions, donations, bookings, or paid community tools.