appointment.cancelled

An appointment was cancelled (via dashboard delete, via the Media Agency API, or as a side-effect of listing cancellation).

Category: Appointment Lifecycle

Emitted when: After the Google Calendar event is deleted AND the Tour cache fields are cleared. Also emitted as a side-effect by the listing.cancelled emitter when the cancelled tour had an active appointment (Wave 3B follow-up).

Envelope

Every delivery wraps the event-specific data block in the canonical envelope documented on the webhook overview page. The body carries SIX keys; the HMAC signature is delivered as the X-Webhook-Signature request header on the inbound POST to your endpoint (NOT as a body field; including it in the body would make the HMAC a function of its own output).

Field	Type	Description
event_id	string	ULID; globally unique. Safe to persist as the dedup key.
event_type	string	Always appointment.cancelled for this event.
api_version	string	Payload schema version (YYYY-MM-DD).
timestamp	integer	Unix epoch seconds at dispatch time.
nonce	string	ULID; unique per delivery, used for replay rejection.
data	object	Event-specific payload (see below).

Delivery also sets three HTTP headers on the inbound POST:

Header	Meaning
X-Webhook-Event-Id	Mirrors event_id; cheaper than parsing the body to dedup.
X-Webhook-Timestamp	Mirrors timestamp for replay-window checks.
X-Webhook-Signature	sha256=<hex> HMAC over timestamp.body.

Data schema

Field	Type	Required	Description
agency_id	string	yes	Agency Id
listing_number	string	yes	Public listing number, 7-char lowercase nanoid ([a-z0-9]{7})
tour_id	string	yes	Hex ObjectId of the Tour document
calendar_event_id	string	yes	Google Calendar event id that was deleted. Globally unique; drives the dedupe operation_id.
scheduled_at	string	yes	UTC moment the appointment was scheduled FOR (not the cancellation time).
cancelled_at	string	yes	UTC moment the deletion was committed.
cancelled_by	string	yes	Actor token: 'apikey:' for API calls, 'user:' for dashboard / listing_cancelled side effects.
reason	string | null	no	Free-form reason supplied on the request body. None when no reason was provided.
source	"dashboard" | "api" | "listing_cancelled"	yes	Source

Sample payload

The sample below is a live fixture. Feed the exact body bytes shown plus the timestamp into the HMAC-SHA256 recipe from the webhook overview using the documented test-vector secret (test_secret_001 ) and you will recover the signature header value printed below.

Body (delivered as the HTTP request body):

{
  "event_id": "evt_70WGW729W5TVAVAPP8PX066NZJ",
  "event_type": "appointment.cancelled",
  "api_version": "2026-04-17",
  "timestamp": 1745339401,
  "nonce": "4Z8YX3GD8J70H1CQ9CCWZGPXS7",
  "data": {
    "agency_id": "user_01HXAGENCY0000000000000",
    "listing_number": "abc1234",
    "tour_id": "66312a4b5c6d7e8f90a1b2c3",
    "calendar_event_id": "evt_cal_01HXCALEVT0000000000",
    "scheduled_at": "2026-05-29T12:00:00Z",
    "cancelled_at": "2026-05-29T12:00:00Z",
    "cancelled_by": "apikey:key_01HXAPIKEY000000000000",
    "reason": "agency_request",
    "source": "dashboard"
  }
}

Signature header (delivered as X-Webhook-Signature on the same request):

sha256=2e50191d8e2a0b917e46fa2ab86b8b2287324616caee242c2c414c6896dee8b8

Retry behaviour

Failed deliveries retry on the sequence 2, 4, 8, 16, 32 seconds (five attempts plus the initial call for a total of six over approximately 62 seconds of wall clock). After the final attempt the delivery lands in the dead-letter queue and the dashboard operator can replay it from Settings > API Keys > Webhook Endpoint > Deliveries. See the webhook overview for the full rules.

Verification

Every receiver MUST verify the X-Webhook-Signature header using the recipe in the webhook overview. Rejecting deliveries whose timestamp is more than 5 minutes off your wall clock (after NTP correction on your side) or whose nonce has already been consumed in the last 10 minutes is part of the contract.