Skip to main content

ADR 0001 — External appointment backends (Qmatic / JCC) are an ADR-022 exception

  • Status: Accepted
  • Date: 2026-06-15
  • Relates to: ADR-019 (integration leaves), ADR-022 (apps consume OR abstractions)
  • Change: openspec/changes/migrate-appointments-to-calendar-leaf

Context​

Procest previously shipped a pluggable appointment-scheduling engine (AppointmentService + AppointmentBackend/{LocalBackend,QmaticBackend,JccBackend}). The LocalBackend path stored events inside the app and rendered its own scheduling UI — a direct duplication of what OpenRegister's calendar integration leaf (CalendarProvider) already provides.

migrate-appointments-to-calendar-leaf moves the internal scheduling surface to the calendar leaf: a case appointment is now a calendar event created/listed/linked/deleted through the leaf's CnCalendarTab, fetched straight from OpenRegister. LocalBackend and the orphaned bespoke Vue (AppointmentSection.vue, AppointmentBookingDialog.vue, appointmentApi.js) were removed.

Decision​

QmaticBackend (Qmatic Orchestra) and JccBackend (JCC Afspraken) stay in-app. They integrate with external municipal appointment systems that own real-world counter capacity, timeslots and queue management (getTimeslots / bookAppointment / rescheduleAppointment against a third-party API). The calendar leaf models NC/CalDAV events, not external-system timeslot booking, so it cannot host these backends.

This is an ADR-022 exception under clause 1 ("fundamentally different domain requirements — external integration the leaf cannot satisfy").

Resolution (a) keep in-app is chosen over (b) move to openconnector because procest is currently the sole fleet consumer of Qmatic/JCC. Should a second app need external municipal scheduling, this decision is revisited in favour of (b) — an openconnector source mirroring shared-pdok-via-openconnector.

Consequences​

  • AppointmentService is narrowed to external backends only; there is no local fallback. An unconfigured/unknown backend now throws a configuration error instead of silently scheduling locally.
  • Zaak-specific appointment metadata the leaf does not model (productId, locationId, cancelToken, reminderSent, no-show status) is retained on the appointment object in procest's register, and AppointmentReminderJob continues to read it.
  • The citizen public cancel-by-token surface (PublicAppointmentController) is retained for external bookings.
  • Follow-up: GH issue tracks the (a)→(b) re-evaluation trigger.