Returns the bookable appointment slots for a clinic's calendar resources over a date range of up to 7 days.

Calendar availability represents the open appointment slots for each resource on a calendar, with all scheduling rules applied — resource schedules, existing appointments, calendar events, designations, and business hours are all accounted for. Availability can be requested for one or more resources and one or more appointment kinds at once; the result is computed independently for each resource-and-kind combination, since an appointment kind's configured duration and designation-based restrictions affect which slots are bookable.

The appointment length used to size the returned slots defaults to the kind's configured duration, but can be overridden with a custom length that applies to every requested kind. Start times are offered on the calendar's block-increment grid rather than stepping by the appointment length, so overlapping start times are returned (for example, a 15-minute grid with a 30-minute appointment offers starts at 8:00, 8:15, and 8:30). Grid alignment is computed in the clinic's local time.

Results are paginated by appointment slot rather than by resource. When a resource's slots span a page boundary, that resource appears on consecutive pages with the remaining slots.

To keep responses bounded, the number of requested appointment kinds per call is capped, and each page returns a bounded number of slots.