leg-aware capacity and wagon sharing

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

@@ -6925,6 +6925,42 @@ export class TrainSchedulingService {
         reverseWagonOrder: schedule.reverseWagonOrder,
       });
 
+    // Heaviest-edge consist usage. Cross-leg slot sharing means plain sums
+    // over-report a multi-stop train — a wagon reused Gelan→Adama and
+    // Adama→Doraleh is two slots but ONE physical wagon, and the train is never
+    // heavier/longer than its heaviest single leg. Same math as the pull-limit
+    // enforcement; coupled-but-empty consist wagons ride every edge.
+    const heaviestLeg = schedule.trainSet
+      ? (() => {
+          const usage = maxEdgeConsistUsage(
+            [
+              ...(schedule.trainSet.wagons ?? []).map((w) => ({
+                lengthMeters: Number(w.lengthMeters),
+                tareWeightTons: w.wagonType
+                  ? Number(w.wagonType.tareWeightTons)
+                  : 0,
+                assignedWeightTons: Number(w.assignedWeightTons),
+                boardYardId: w.boardYardId ?? null,
+                alightYardId: w.alightYardId ?? null,
+                allocations: w.allocations ?? [],
+              })),
+              ...emptyConsistWagons.map((w) => ({
+                lengthMeters: w.lengthMeters,
+                tareWeightTons: Number(w.tareWeightTons ?? 0),
+                assignedWeightTons: 0,
+                allocations: [],
+              })),
+            ],
+            this.mapScheduleStops(schedule).map((s) => s.yardId),
+          );
+          return {
+            grossWeightTons: roundTons(usage.grossWeightTons),
+            lengthMeters: roundTons(usage.lengthMeters),
+            loadedWagonCount: usage.loadedWagonCount,
+          };
+        })()
+      : null;
+
     return {
       id: schedule.id,
       reference: schedule.reference ?? null,
@@ -6997,6 +7033,9 @@ export class TrainSchedulingService {
             wagonCount: schedule.trainSet.wagonCount,
             totalWeightTons: roundTons(Number(schedule.trainSet.totalWeightTons)),
             totalLengthMeters: roundTons(Number(schedule.trainSet.totalLengthMeters)),
+            // What the locomotives actually haul: usage on the corridor's
+            // heaviest edge, not the sum of every leg's slots.
+            heaviestLeg,
             locomotive: schedule.trainSet.locomotive
               ? {
                   id: schedule.trainSet.locomotive.id,