Create a webhook subscription in Cal.com API v2 (POST /v2/webhooks) with subscriberUrl, triggers, active flag, and an optional payload template and signing secret.

Documented steps

1. Authenticate with Authorization: 'Bearer cal_live_xxx' (or a cal_ test key), created in Cal.com Settings > Security.
2. Set Content-Type: application/json.
3. Send POST https://api.cal.com/v2/webhooks.
4. Include the body fields subscriberUrl (string, your receiving endpoint), triggers (array of trigger enum strings, e.g. ['BOOKING_CREATED','BOOKING_CANCELLED']), and active (boolean).
5. Optionally include payloadTemplate, a string using double-brace syntax, e.g. '{"organizer":"{{organizer.name}}","booker":"{{attendees.0.name}}"}', to customize the delivered payload shape.
6. Optionally include secret (string) — this is the HMAC key used to verify the X-Cal-Signature-256 header on incoming deliveries.
7. Optionally include version (documented enum value '2021-10-20'); omit to use the default.
8. Expect HTTP 201 with {status:'success', data:{id, userId, subscriberUrl, active, triggers, payloadTemplate, secret}} — store the id and secret.
9. For an event-type-scoped webhook, POST https://api.cal.com/v2/event-types/{eventTypeId}/webhooks with the same body fields.
10. For an organization-scoped webhook, POST https://api.cal.com/v2/organizations/{orgId}/webhooks; this requires org admin role and the ORG_WEBHOOK_WRITE scope / webhook.create permission.
11. With OAuth rather than an API key, the general webhook write operation requires the WEBHOOK_WRITE scope.
12. Docs: https://cal.com/docs/api-reference/v2/webhooks/create-a-webhook