Notifications and tracking

Register webhooks before creating production withdrawals. The Events reference defines withdrawal, account, and whitelisted-own-account event payloads.

For each delivery:

1. verify the Ed25519 signature against the raw request body;
2. deduplicate by event id;
3. persist or enqueue the notification;
4. return 2xx promptly; and
5. fetch the related resource when current state matters.

Use polling and periodic reconciliation as recovery mechanisms. Webhook delivery is at least once and is not a substitute for authoritative resource reads.