backend/src/common/errors/error-codes.ts

@@ -63,6 +63,7 @@ export const ErrorCode = {
   CONFLICT: 'CONFLICT',
   CONFLICT_FUTURE_APPOINTMENTS: 'CONFLICT_FUTURE_APPOINTMENTS',
   APPOINTMENT_PATIENT_LOCKED: 'APPOINTMENT_PATIENT_LOCKED',
+  APPOINTMENT_HAS_TREATMENT: 'APPOINTMENT_HAS_TREATMENT',
   BAD_REQUEST: 'BAD_REQUEST',
   INTERNAL_ERROR: 'INTERNAL_ERROR',
 } as const;

backend/src/modules/appointments/appointments.service.ts

@@ -1,6 +1,7 @@
 import {
   BadRequestException,
   ForbiddenException,
+  HttpStatus,
   Injectable,
   NotFoundException,
 } from '@nestjs/common';
@@ -16,6 +17,7 @@ import { ListAppointmentsDto } from './dto/list-appointments.dto';
 import { UpdateAppointmentDto } from './dto/update-appointment.dto';
 import { TreatmentCatalogService } from '../treatment-catalog/treatment-catalog.service';
 import { hasEffectivePermission } from '../../common/membership-permissions';
+import { AppException, ErrorCode } from '../../common/errors';
 
 const MS_PER_DAY = 86_400_000;
 
@@ -215,9 +217,7 @@ export class AppointmentsService {
         select: { id: true },
       });
       if (linkedTreatment) {
-        throw new BadRequestException(
-          'Cannot change the patient while a treatment is linked to this appointment',
-        );
+        throw new AppException(ErrorCode.APPOINTMENT_PATIENT_LOCKED, HttpStatus.CONFLICT);
       }
     }
 
@@ -256,13 +256,17 @@ export class AppointmentsService {
 
     const existing = await this.prisma.appointment.findFirst({
       where: { id, organizationId },
-      select: { id: true },
+      select: { id: true, treatment: { select: { id: true } } },
     });
 
     if (!existing) {
       throw new NotFoundException('Appointment not found');
     }
 
+    if (existing.treatment) {
+      throw new AppException(ErrorCode.APPOINTMENT_HAS_TREATMENT, HttpStatus.CONFLICT);
+    }
+
     await this.prisma.appointment.delete({
       where: { id },
     });

frontend/messages/en.json

@@ -582,6 +582,7 @@
     "confirmRemove": "Remove this appointment?",
     "successRemoved": "Appointment removed.",
     "errorDelete": "Could not delete appointment.",
+    "deleteBlockedHint": "This appointment cannot be deleted because a treatment is linked to it.",
     "errorLoadSchedule": "Failed to load schedule.",
     "successPatientSaved": "Patient {firstName} {lastName} was saved.",
     "searchPlaceholder": "Search existing patients",
@@ -1013,6 +1014,7 @@
     "CONFLICT": "This action conflicts with existing data.",
     "CONFLICT_FUTURE_APPOINTMENTS": "You cannot stop participating in treatments while you have future appointments. Reassign or cancel them first.",
     "APPOINTMENT_PATIENT_LOCKED": "Cannot change the patient while a treatment is linked to this appointment.",
+    "APPOINTMENT_HAS_TREATMENT": "This appointment cannot be deleted because a treatment is linked to it.",
     "BAD_REQUEST": "The request could not be processed.",
     "INTERNAL_ERROR": "Something went wrong on our end. Please try again later."
   }

frontend/messages/fa.json

@@ -583,6 +583,7 @@
     "confirmRemove": "این نوبت حذف شود؟",
     "successRemoved": "نوبت حذف شد.",
     "errorDelete": "حذف نوبت امکان‌پذیر نبود.",
+    "deleteBlockedHint": "به‌دلیل وجود درمان مرتبط با این نوبت، امکان حذف آن وجود ندارد.",
     "errorLoadSchedule": "بارگذاری برنامه ناموفق بود.",
     "successPatientSaved": "بیمار {firstName} {lastName} ذخیره شد.",
     "searchPlaceholder": "جستجوی بیماران موجود",
@@ -1014,6 +1015,7 @@
     "CONFLICT": "این عمل با داده‌های موجود در تضاد است.",
     "CONFLICT_FUTURE_APPOINTMENTS": "تا وقتی نوبت‌های آینده دارید نمی‌توانید مشارکت در درمان را متوقف کنید. ابتدا آن‌ها را لغو یا واگذار کنید.",
     "APPOINTMENT_PATIENT_LOCKED": "تا وقتی درمانی به این نوبت متصل است، امکان تغییر بیمار وجود ندارد.",
+    "APPOINTMENT_HAS_TREATMENT": "به‌دلیل وجود درمان مرتبط با این نوبت، امکان حذف آن وجود ندارد.",
     "BAD_REQUEST": "درخواست قابل پردازش نبود.",
     "INTERNAL_ERROR": "مشکلی در سرور رخ داد. لطفاً بعداً تلاش کنید."
   }

frontend/messages/nl.json

@@ -582,6 +582,7 @@
     "confirmRemove": "Deze afspraak verwijderen?",
     "successRemoved": "Afspraak verwijderd.",
     "errorDelete": "Kon afspraak niet verwijderen.",
+    "deleteBlockedHint": "Deze afspraak kan niet worden verwijderd omdat er een behandeling aan is gekoppeld.",
     "errorLoadSchedule": "Rooster laden mislukt.",
     "successPatientSaved": "Patiënt {firstName} {lastName} is opgeslagen.",
     "searchPlaceholder": "Bestaande patiënten zoeken",
@@ -1013,6 +1014,7 @@
     "CONFLICT": "Deze actie conflicteert met bestaande gegevens.",
     "CONFLICT_FUTURE_APPOINTMENTS": "U kunt niet stoppen met deelnemen aan behandelingen zolang u toekomstige afspraken hebt. Wijs ze eerst opnieuw toe of annuleer ze.",
     "APPOINTMENT_PATIENT_LOCKED": "De patiënt kan niet worden gewijzigd zolang er een behandeling aan deze afspraak is gekoppeld.",
+    "APPOINTMENT_HAS_TREATMENT": "Deze afspraak kan niet worden verwijderd omdat er een behandeling aan is gekoppeld.",
     "BAD_REQUEST": "Het verzoek kon niet worden verwerkt.",
     "INTERNAL_ERROR": "Er is iets misgegaan aan onze kant. Probeer het later opnieuw."
   }

frontend/src/components/ui/appointments/AppointmentBookingModal.tsx

@@ -310,6 +310,10 @@ export function AppointmentBookingModal({
 
         {error && <p className="text-sm text-red-400">{error}</p>}
 
+        {editingAppointment?.hasTreatment ? (
+          <p className="text-sm text-text-secondary">{t('deleteBlockedHint')}</p>
+        ) : null}
+
         <div className="flex flex-col-reverse gap-2 sm:flex-row sm:flex-wrap sm:items-center sm:justify-between">
           {editingAppointment && canDelete && onDelete ? (
             <Button

frontend/src/components/ui/appointments/AppointmentsPage.tsx

@@ -279,7 +279,12 @@ export function AppointmentsPage() {
         }}
         onSubmit={handleSaveAppointment}
         loading={savingAppointment}
-
+        canDelete={
+          canManageAppointments &&
+          !isViewingPastDay &&
+          !!activeEditingAppointment &&
+          !activeEditingAppointment.hasTreatment
+        }
         onDelete={() => void handleDeleteEditingAppointment()}
         deleting={deletingAppointment}
       />