changes

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

@@ -3444,19 +3444,22 @@ export class BookingBatchService implements OnModuleInit {
 
   /**
    * Physical wagons marshalled in the schedule's built train, or null when the
-   * schedule has no built train (or the consist is still empty) and the legacy
-   * locomotive-derived capacity must apply. This count is what caps a built
-   * train's bookings: 50 wagons coupled → 50 wagon slots, no more.
+   * schedule has NO built train and the legacy locomotive-derived capacity must
+   * apply. This count is what caps a built train's bookings: 50 wagons coupled
+   * → 50 wagon slots, no more.
+   *
+   * A built train with an EMPTY consist returns 0, NOT null: zero coupled
+   * wagons means zero capacity. Folding that case into null used to hand an
+   * un-consisted train the abstract locomotive budget, so an empty train
+   * advertised its full maxWagons as free space and accepted bookings the
+   * allocator could never place.
    */
   private async builtTrainWagonCount(
     schedule: TrainSchedule,
   ): Promise<number | null> {
     const trainId = schedule.trainSet?.train?.id;
     if (!trainId) return null;
-    const count = await this.dataSource
-      .getRepository(Wagon)
-      .count({ where: { trainId } });
-    return count > 0 ? count : null;
+    return this.dataSource.getRepository(Wagon).count({ where: { trainId } });
   }
 
   /**

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

@@ -7090,9 +7090,19 @@ export class TrainSchedulingService {
 
     await this.dataSource.transaction(async (manager) => {
       await manager.getRepository(TrainSetWagon).delete(trainSetWagonId);
+      // Recount from the slot rows rather than decrementing the cached counter.
+      // A blind `wagonCount - 1` desyncs the moment two removals race or the
+      // in-memory schedule graph is stale, and the counter is what the schedule
+      // capacity math reads.
+      const remaining = await manager.getRepository(TrainSetWagon).find({
+        where: { trainSetId: schedule.trainSetId },
+        select: { id: true, lengthMeters: true },
+      });
       await manager.getRepository(TrainSet).update(schedule.trainSetId, {
-        wagonCount: Math.max(0, (schedule.trainSet?.wagonCount ?? 0) - 1),
-        totalLengthMeters: Math.max(0, (schedule.trainSet?.totalLengthMeters ?? 0) - (wagon.lengthMeters ?? 0)),
+        wagonCount: remaining.length,
+        totalLengthMeters: roundTons(
+          remaining.reduce((sum, w) => sum + (Number(w.lengthMeters) || 0), 0),
+        ),
       });
     });