Handle airline schedule changes and order cancellation webhooks in Duffel

Steps

1. Register a webhook endpoint in the Duffel dashboard (or via POST /webhooks) subscribing to event types: order.airline_initiated_change_created, order.cancelled, order.updated.
2. When order.airline_initiated_change_created fires, fetch the change details via GET /air/airline_initiated_changes/{id}; the object includes slices with new departure/arrival times and an action_taken field.
3. Evaluate whether the change is acceptable by your policy (e.g. less than 2 hours shift = auto-accept, more = prompt human); to accept, POST /air/airline_initiated_changes/{id}/actions/accept.
4. If the change is unacceptable and the airline allows it, fetch the order's available_actions and check for cancel or change; initiate a voluntary cancel via POST /air/order_cancellations with order_id, then confirm it.
5. On order.cancelled webhook, update your internal booking record status and trigger any downstream refund or notification logic; check refund_to field on the cancellation object to know whether refund goes to original payment or Duffel balance.
6. Implement idempotent webhook handling — Duffel may deliver the same event more than once; use the event id to deduplicate before processing.