A new event, posted to each endpoint whose kinds include it
postWebhookevent
Headers
UIDWatch-Signaturestring required
t=<unix seconds>,v1=<hex HMAC-SHA256 of "t.body" with the endpoint secret>
UIDWatch-Event-Idstring required
The same for every attempt of one event
UIDWatch-Delivery-Idstring required
One delivery to one endpoint
Payload
Response
Delivered. Anything else is retried after 1 min, 5 min, 30 min, 2 h, 6 h and 12 h.
Changes
Webhooks have no change history: a webhook is keyed by its event name rather than a path and method, so no recorded change can name it.