Check a booking, including whether its EHR insert has completed (`ehr_writeback`).

Booking status by booking_ref, as two independent fields. booking_status
(formerly status) is confirmed while the booking stands and cancelled if
the appointment was cancelled or removed after booking. ehr_writeback is
pending until the appointment reaches the practice's EHR, confirmed once it
has, failed if the sync to the practice's EHR permanently failed (contact
support - this will not resolve on its own), and unknown if the appointment
record can no longer be found (stop polling and verify with the practice).
Practices without an EHR integration have nothing to write back to, so their
bookings stay pending. message restates the combined state in one sentence
that is safe to relay as-is. start_iso tracks the live appointment time (a
practice-side reschedule moves it; start_local stays as booked).

Example request

curl 'https://nexhealth.info/intent/booking/status?booking_ref=bkg_4d81f30a6c2e49b7a5d81f30a6c2e49b' \
  -H 'Authorization: Bearer <token>'

Example success response

{ "ok": true,
  "message": "Booked in NexHealth. The appointment is queued for insertion into the practice's EHR; poll booking/status until ehr_writeback is confirmed.",
  "booking": { "booking_ref": "bkg_4d81f30a6c2e49b7a5d81f30a6c2e49b",
               "booking_status": "confirmed",
               "ehr_writeback": "pending",
               "appointment_id": 918273,
               "start_local": "Mon, Aug 10 · 9:00 AM PDT",
               "start_iso": "2026-08-10T16:00:00Z",
               "duration_minutes": 30,
               "provider": "Dr. Sarah Johnson",
               "location": { "location_id": 42, "name": "Main St Dental", "address": "1 Main St, Seattle, WA, 98101" },
               "patient": { "first_name": "Jane", "last_name": "Doe" } } }

Reason catalog (branch on reason when ok is false)