When an experience has an availabilityEndpoint, Riposte POSTs every slot lookup to your service using the SchedulerAvailabilityCallbackPayload structure. The payload includes the experience context plus the visitor’s exact filter: date range, durationMinutes, optional attendees, booking-form answers, and any metadata you attached while proxying the widget request.
Your handler must return a SchedulerAvailabilityResponse with a generatedAt timestamp and at least one slots entry (or an explicit empty array). If generatedAt is missing the widget refuses to render and logs generatedAt is required.