fix issue

apps/edr-freight-api/src/modules/train-scheduling/booking-batch.smart-need.spec.ts

@@ -86,6 +86,40 @@ describe('BookingBatchService.smartBulkNeed', () => {
     expect(call(booking(695), stock, contested)).toBeNull();
   });
 
+  it('S-2026-00020 shape: 42x40ft eat the NW5, 200T bulk still seats on the 10 coupled PW2', () => {
+    // The staging complaint: a built train of 42 NW5 + 10 PW2, containers
+    // hold every NW5, and a bulk booking sits in "Ready for batch" while the
+    // PW2 ride empty. The chain: committed containers drain NW5 from the
+    // ledger (their types cannot touch PW2), then the smart gate must seat
+    // 200T of Perishable on the 10 PW2 at the 20T cap.
+    const stock = new WagonStockLedger(
+      new Map([
+        [nw5.id, 42],
+        [pw2.id, 10],
+      ]),
+      2, // DCT -> Dire -> GMP: two edges
+    );
+    // Committed container booking rides Dire->GMP (edge 1) on 42 NW5 —
+    // container-capable types only, exactly how stockLedgerFor debits it.
+    stock.consume([nw5.id], 42, { fromEdge: 1, toEdge: 2 });
+    expect(stock.availableFor([nw5.id], { fromEdge: 0, toEdge: 2 })).toBe(0);
+    expect(stock.availableFor([pw2.id], { fromEdge: 0, toEdge: 2 })).toBe(10);
+
+    const smart = (
+      service as unknown as {
+        smartBulkNeed: (
+          b: Booking,
+          d: unknown,
+          s: WagonStockLedger,
+          l: { fromEdge: number; toEdge: number },
+          r: Map<string, number>,
+        ) => { need: { wagons: number }; perType: Array<{ wagonTypeId: string; wagons: number }> } | null;
+      }
+    ).smartBulkNeed(booking(200), wagonDims, stock, { fromEdge: 0, toEdge: 2 }, contested);
+    expect(smart).not.toBeNull();
+    expect(smart!.perType).toEqual([{ wagonTypeId: pw2.id, wagons: 10 }]);
+  });
+
   it('uncontested types fall back to biggest per-cargo take (fewest wagons)', () => {
     const stock = new WagonStockLedger(
       new Map([