update train scheduling logic to clear trainScheduleId when unassigning bookings

apps/edr-freight-api/src/modules/bookings/bookings.repository.ts

@@ -1269,7 +1269,12 @@ export class BookingsRepository extends BaseRepository<Booking> {
     fields: Partial<
       Pick<
         Booking,
-        'schedulingStatus' | 'wagonsRequired' | 'scheduledAt' | 'holdStartedAt' | 'holdExpiresAt'
+        | 'schedulingStatus'
+        | 'wagonsRequired'
+        | 'scheduledAt'
+        | 'holdStartedAt'
+        | 'holdExpiresAt'
+        | 'trainScheduleId'
       >
     >,
     manager?: EntityManager,

apps/edr-freight-api/src/modules/train-scheduling/train-scheduling.service.ts

@@ -1387,9 +1387,13 @@ export class TrainSchedulingService {
 
       const booking = await this.bookingsRepository.findById(bookingId);
       const schedulingStatus = this.resolvePostUnassignStatus(booking);
+      // Clear the schedule pointer too: unassign fully detaches the booking from
+      // this train. Leaving trainScheduleId set glued the booking to a schedule
+      // that may then be dispatched/cancelled/deleted, orphaning it — the
+      // assign-bookings parity guard would reject it from every OTHER schedule.
       await this.bookingsRepository.updateSchedulingFields(
         bookingId,
-        { schedulingStatus, wagonsRequired: null },
+        { schedulingStatus, wagonsRequired: null, trainScheduleId: null },
         manager,
       );
 
@@ -3043,9 +3047,15 @@ export class TrainSchedulingService {
       }
       for (const sb of schedule.scheduleBookings ?? []) {
         const booking = await this.bookingsRepository.findById(sb.bookingId);
+        // Detach from the cancelled schedule — clear the pointer so the freed
+        // booking can be assigned to another train. Leaving it set orphans the
+        // booking against a schedule that is about to be gone.
         await this.bookingsRepository.updateSchedulingFields(
           sb.bookingId,
-          { schedulingStatus: this.resolvePostUnassignStatus(booking) },
+          {
+            schedulingStatus: this.resolvePostUnassignStatus(booking),
+            trainScheduleId: null,
+          },
           manager,
         );
       }