fix: complete first version issue remediation

api/src/billing/billing.service.spec.ts

@@ -143,6 +143,31 @@ describe('BillingService', () => {
     });
   });
 
+  it('returns the historical balance after each manual recharge', async () => {
+    const prisma = createPrismaMock();
+    prisma.rechargeOrder.findMany.mockResolvedValue([
+      { id: 'order-1', tenantId: 'tenant-1', payMethod: 'manual_topup', amountCents: 2000 },
+      { id: 'order-2', tenantId: 'tenant-1', payMethod: 'manual_topup', amountCents: -300 },
+    ]);
+    prisma.accountTransaction.findMany.mockResolvedValue([
+      { relatedId: 'order-1', balanceAfter: 3000 },
+      { relatedId: 'order-2', balanceAfter: 2700 },
+    ]);
+    const service = new BillingService(prisma as never);
+
+    await expect(service.listManualRechargeRecords()).resolves.toEqual([
+      expect.objectContaining({ id: 'order-1', balanceAfterCents: 3000 }),
+      expect.objectContaining({ id: 'order-2', balanceAfterCents: 2700 }),
+    ]);
+    expect(prisma.accountTransaction.findMany).toHaveBeenCalledWith({
+      where: {
+        relatedType: 'recharge_order',
+        relatedId: { in: ['order-1', 'order-2'] },
+      },
+      select: { relatedId: true, balanceAfter: true },
+    });
+  });
+
   it('allows negative manual recharge amounts for balance correction', async () => {
     const prisma = createPrismaMock();
     const service = new BillingService(prisma as never);

api/src/billing/billing.service.ts

@@ -133,8 +133,8 @@ export class BillingService {
     });
   }
 
-  listManualRechargeRecords(tenantId?: string) {
-    return this.prisma.rechargeOrder.findMany({
+  async listManualRechargeRecords(tenantId?: string) {
+    const orders = await this.prisma.rechargeOrder.findMany({
       where: {
         tenantId,
         payMethod: 'manual_topup',
@@ -143,6 +143,24 @@ export class BillingService {
       orderBy: { createdAt: 'desc' },
       take: 100,
     });
+    const orderIds = orders.map((order) => order.id);
+    if (orderIds.length === 0) {
+      return orders;
+    }
+
+    const transactions = await this.prisma.accountTransaction.findMany({
+      where: {
+        relatedType: 'recharge_order',
+        relatedId: { in: orderIds },
+      },
+      select: { relatedId: true, balanceAfter: true },
+    });
+    const balanceAfterByOrderId = new Map(transactions.map((transaction) => [transaction.relatedId, transaction.balanceAfter]));
+
+    return orders.map((order) => ({
+      ...order,
+      balanceAfterCents: balanceAfterByOrderId.get(order.id) ?? null,
+    }));
   }
 
   async createRechargeOrder(data: CreateRechargeOrderDto) {