feat: balance api

api_v1/tests.py

@@ -22,7 +22,7 @@ from basic_info.models import (
     WareHouse,
     WareHouseModeEnum,
 )
-from business import models as business_models
+from business import models as business_models, services
 from stock import models as stock_models
 from api_v1 import tasks
 
@@ -494,8 +494,7 @@ class PaymentOrderAPITestCase(TestCase):
             {'action': 'cancel'},
             format='json',
         )
-        self.assertEqual(response_cancel.status_code, status.HTTP_200_OK)
-        self.assertEqual(response_cancel.data['status'], business_models.PaymentOrderStatusEnum.CANCELLED)
+        self.assertEqual(response_cancel.status_code, status.HTTP_400_BAD_REQUEST)
 
     def test_payment_order_requires_amount(self):
         payload = {**self.payload}
@@ -569,6 +568,81 @@ class ReceiptOrderAPITestCase(TestCase):
         response = self.client.post('/api/v1/receipt-orders/', payload, format='json')
         self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
         self.assertIn('amount 必须大于 0', response.data['error'])
+
+
+class CustomerBalanceAPITestCase(TestCase):
+    def setUp(self):
+        self.merchant = Merchant.objects.create(name='余额商户', type=MerchantTypeEnum.FACTORY)
+        self.customer = Customer.objects.create(
+            merchant=self.merchant,
+            name='余额客户',
+            mobile='13800000000',
+            created_by=None,
+        )
+        self.user = User.objects.create_user(username='balance_user', password='pass123')
+        self.employee = Employee.objects.create(
+            merchant=self.merchant,
+            sys_user=self.user,
+            name='财务查询',
+            status=EmployeeStatusEnum.ACTIVE,
+        )
+        self.client = APIClient()
+        self.client.force_authenticate(user=self.user)
+
+    def test_customer_balance_defaults_to_zero(self):
+        response = self.client.get(f'/api/v1/customers/{self.customer.id}/balance/')
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        self.assertEqual(response.data['balance'], '0')
+
+    def test_customer_balance_reflects_sales_and_receipts(self):
+        # 创建销售单
+        product_category = ProductCategory.objects.create(
+            merchant=self.merchant,
+            name='余额品类',
+            product_prefix='BAL',
+        )
+        product = Product.objects.create(
+            merchant=self.merchant,
+            category=product_category,
+            name='余额产品',
+            human_id='BAL-001',
+            unit=ProductUnitEnum.METER,
+        )
+        warehouse = WareHouse.objects.create(
+            merchant=self.merchant,
+            name='余额仓',
+            mode=WareHouseModeEnum.RESTRICT_IN,
+        )
+        order = services.create_sales_order(
+            merchant=self.merchant,
+            customer=self.customer,
+            order_date='2025-11-26',
+            warehouse=warehouse,
+            operator=self.employee,
+            items=[{'product_id': product.id, 'numbers': [5], 'price': '10', 'unit': '米'}],
+        )
+        services.review_sales_order(
+            sales_order=order,
+            target_status=business_models.SalesOrderStatusEnum.APPROVED,
+            reviewed_by=self.user,
+        )
+        response = self.client.get(f'/api/v1/customers/{self.customer.id}/balance/')
+        self.assertEqual(response.data['balance'], '50.00')
+
+        receipt = services.create_receipt_order(
+            merchant=self.merchant,
+            customer=self.customer,
+            receipt_date='2025-11-27',
+            amount='20',
+            operator=self.employee,
+        )
+        services.review_receipt_order(
+            receipt_order=receipt,
+            target_status=business_models.ReceiptOrderStatusEnum.APPROVED,
+            reviewed_by=self.user,
+        )
+        response = self.client.get(f'/api/v1/customers/{self.customer.id}/balance/')
+        self.assertEqual(response.data['balance'], '30.00')
 @override_settings(
     CELERY_TASK_ALWAYS_EAGER=True,
     CELERY_TASK_EAGER_PROPAGATES=True,

api_v1/urls.py

@@ -10,10 +10,11 @@ from .views import (
     users,
     print_count,
 )
-from .business.purchase import views as purchase_views
-from .business.sales import views as sales_views
-from .business.payment import views as payment_views
-from .business.receipt import views as receipt_views
+from .views.business.purchase import views as purchase_views
+from .views.business.sales import views as sales_views
+from .views.business.payment import views as payment_views
+from .views.business.receipt import views as receipt_views
+from .views.business.balance import views as balance_views
 from .views.stock_change_views.snapshot import StockSnapshotListView
 from .views.printing.views import PrintingOrderViewSet, PrintingJobViewSet, PlateOrderViewSet
 from .views.upload import UploadFileViewSet
@@ -69,6 +70,7 @@ urlpatterns = [
     path('payment-orders/<int:pk>/review/', payment_views.PaymentOrderReviewView.as_view(), name='payment_order_review'),
     path('receipt-orders/', receipt_views.ReceiptOrderView.as_view(), name='receipt_orders'),
     path('receipt-orders/<int:pk>/review/', receipt_views.ReceiptOrderReviewView.as_view(), name='receipt_order_review'),
+    path('customers/<int:customer_id>/balance/', balance_views.CustomerBalanceView.as_view(), name='customer_balance'),
     path('health/', healthy.HealthCheckView.as_view(), name='health_check'),
     path('print-count/delta/', print_count.adjust_print_count, name='print_count_delta'),
     

api_v1/views/business/README.md

@@ -150,6 +150,13 @@
 
 ---
 
+## 7. 客户欠款查询
+
+- **GET** `/api/v1/customers/<id>/balance/`
+- **描述**：返回指定客户当前的应收余额（审批通过的销售单金额累加减去收款单金额），数据来源于余额表，因此查询为 O(1)。
+- **响应**：`{"customer": 12, "customer_name": "张三", "balance": "1234.50"}`
+  - `balance` 为字符串格式的十进制数，正数表示客户欠款，应收；负数表示已收超额。
+
 如需对 `items` 结构、仓库模式或审批流程做深入了解，请参阅：
 - `docs/purchase_order_approval_and_red_flush.md`
 - `docs/sales_order_approval_and_red_flush.md`

api_v1/views/business/balance/__init__.py

@@ -0,0 +1,4 @@
+"""
+余额相关 API 视图。
+"""
+

api_v1/views/business/balance/views.py

@@ -0,0 +1,36 @@
+from decimal import Decimal
+
+from rest_framework import views
+from rest_framework.permissions import IsAuthenticated
+from rest_framework.response import Response
+
+from basic_info import models as basic_models
+from business import services as business_services
+from api_v1.views.stock_change_views.mixins import StockChangeViewMixin
+
+
+class CustomerBalanceView(StockChangeViewMixin, views.APIView):
+    permission_classes = [IsAuthenticated]
+
+    def get(self, request, customer_id: int):
+        if not self.check_employee_permission(request):
+            return self.permission_error_response('无权限访问')
+
+        merchant = request.user.employee.merchant
+        try:
+            customer = basic_models.Customer.objects.get(id=customer_id, merchant=merchant)
+        except basic_models.Customer.DoesNotExist:
+            return self.not_found_response('客户不存在')
+
+        balance: Decimal = business_services.BalanceService.get_customer_balance(
+            merchant=merchant,
+            customer=customer,
+        )
+        return Response(
+            {
+                'customer': customer.id,
+                'customer_name': customer.name,
+                'balance': str(balance),
+            }
+        )
+

business/ARCHITECTURE.md

@@ -39,6 +39,7 @@
 - **SalesOrder**（销售单）：`direction=-1`，`counterparty=customer`，含库存明细；严进严出模式需记录 `consume_detail_ids`。
 - **PaymentOrder**（付款单）：`direction=-1`，`counterparty=supplier`，仅金额字段，不触发库存。
 - **ReceiptOrder**（收款单）：`direction=-1`，`counterparty=customer`，仅金额字段，不触发库存。
+- **SupplierBalance / CustomerBalance**：实时维护供应商应付、客户应收余额，所有审批通过的带金额单据都会写入，供查询接口和报表使用。
 
 通过 mixin，所有单据都具备：
 - 统一的金额聚合与方向计算（资金/库存可共用 `get_signed_total_amount()`）

business/migrations/0012_customerbalance_supplierbalance.py

@@ -0,0 +1,48 @@
+# Generated by Django 5.2.7 on 2025-11-30 14:17
+
+import django.db.models.deletion
+from decimal import Decimal
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('basic_info', '0016_merchantsetting_type'),
+        ('business', '0011_paymentorder_receiptorder'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='CustomerBalance',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('created_at', models.DateTimeField(auto_now_add=True, verbose_name='创建时间')),
+                ('updated_at', models.DateTimeField(auto_now=True, verbose_name='更新时间')),
+                ('balance', models.DecimalField(decimal_places=2, default=Decimal('0'), max_digits=15, verbose_name='应收余额')),
+                ('customer', models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, related_name='balances', to='basic_info.customer', verbose_name='客户')),
+                ('merchant', models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, related_name='customer_balances', to='basic_info.merchant', verbose_name='所属商户')),
+            ],
+            options={
+                'verbose_name': '客户余额',
+                'verbose_name_plural': '客户余额',
+                'unique_together': {('merchant', 'customer')},
+            },
+        ),
+        migrations.CreateModel(
+            name='SupplierBalance',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('created_at', models.DateTimeField(auto_now_add=True, verbose_name='创建时间')),
+                ('updated_at', models.DateTimeField(auto_now=True, verbose_name='更新时间')),
+                ('balance', models.DecimalField(decimal_places=2, default=Decimal('0'), max_digits=15, verbose_name='应付余额')),
+                ('merchant', models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, related_name='supplier_balances', to='basic_info.merchant', verbose_name='所属商户')),
+                ('supplier', models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, related_name='balances', to='basic_info.supplier', verbose_name='供应商')),
+            ],
+            options={
+                'verbose_name': '供应商余额',
+                'verbose_name_plural': '供应商余额',
+                'unique_together': {('merchant', 'supplier')},
+            },
+        ),
+    ]

business/models.py

@@ -420,3 +420,45 @@ class ReceiptOrder(OrderDirectionMixin, OrderCounterpartyMixin, ModelBase):
 
     def get_counterparty_field_name(self) -> str:
         return 'customer'
+
+
+class SupplierBalance(ModelBase):
+    merchant = models.ForeignKey(
+        basic_info_models.Merchant,
+        on_delete=models.PROTECT,
+        related_name='supplier_balances',
+        verbose_name='所属商户',
+    )
+    supplier = models.ForeignKey(
+        basic_info_models.Supplier,
+        on_delete=models.PROTECT,
+        related_name='balances',
+        verbose_name='供应商',
+    )
+    balance = models.DecimalField(max_digits=15, decimal_places=2, default=Decimal('0'), verbose_name='应付余额')
+
+    class Meta:
+        verbose_name = '供应商余额'
+        verbose_name_plural = '供应商余额'
+        unique_together = ('merchant', 'supplier')
+
+
+class CustomerBalance(ModelBase):
+    merchant = models.ForeignKey(
+        basic_info_models.Merchant,
+        on_delete=models.PROTECT,
+        related_name='customer_balances',
+        verbose_name='所属商户',
+    )
+    customer = models.ForeignKey(
+        basic_info_models.Customer,
+        on_delete=models.PROTECT,
+        related_name='balances',
+        verbose_name='客户',
+    )
+    balance = models.DecimalField(max_digits=15, decimal_places=2, default=Decimal('0'), verbose_name='应收余额')
+
+    class Meta:
+        verbose_name = '客户余额'
+        verbose_name_plural = '客户余额'
+        unique_together = ('merchant', 'customer')

business/services.py

@@ -18,6 +18,66 @@ from .tasks import (
     create_purchase_order_stock_entries,
     create_sales_order_stock_entries,
 )
+class BalanceService:
+    @staticmethod
+    def adjust_supplier_balance(
+        *,
+        merchant: basic_info_models.Merchant,
+        supplier: basic_info_models.Supplier,
+        delta: Decimal,
+    ):
+        with transaction.atomic():
+            balance, _ = models.SupplierBalance.objects.select_for_update().get_or_create(
+                merchant=merchant,
+                supplier=supplier,
+                defaults={'balance': Decimal('0')},
+            )
+            balance.balance += delta
+            balance.save(update_fields=['balance', 'updated_at'])
+
+    @staticmethod
+    def adjust_customer_balance(
+        *,
+        merchant: basic_info_models.Merchant,
+        customer: basic_info_models.Customer,
+        delta: Decimal,
+    ):
+        with transaction.atomic():
+            balance, _ = models.CustomerBalance.objects.select_for_update().get_or_create(
+                merchant=merchant,
+                customer=customer,
+                defaults={'balance': Decimal('0')},
+            )
+            balance.balance += delta
+            balance.save(update_fields=['balance', 'updated_at'])
+
+    @staticmethod
+    def get_customer_balance(
+        *,
+        merchant: basic_info_models.Merchant,
+        customer: basic_info_models.Customer,
+    ) -> Decimal:
+        balance = models.CustomerBalance.objects.filter(
+            merchant=merchant,
+            customer=customer,
+        ).first()
+        if balance is None:
+            return Decimal('0')
+        return balance.balance
+
+    @staticmethod
+    def get_supplier_balance(
+        *,
+        merchant: basic_info_models.Merchant,
+        supplier: basic_info_models.Supplier,
+    ) -> Decimal:
+        balance = models.SupplierBalance.objects.filter(
+            merchant=merchant,
+            supplier=supplier,
+        ).first()
+        if balance is None:
+            return Decimal('0')
+        return balance.balance
 
 
 logger = logging.getLogger(__name__)
@@ -296,12 +356,37 @@ def review_payment_order(
     if order.status == target_status:
         return order
 
+    if target_status == models.PaymentOrderStatusEnum.APPROVED:
+        if order.status == models.PaymentOrderStatusEnum.CANCELLED:
+            raise ValueError('作废状态的付款单无法再次审批')
         with transaction.atomic():
-        order.status = target_status
-        order.save(update_fields=['status', 'updated_at'])
+            locked = models.PaymentOrder.objects.select_related(
+                'merchant', 'supplier'
+            ).select_for_update().get(id=order.id)
+            if locked.status == models.PaymentOrderStatusEnum.APPROVED:
+                return locked
+            if locked.status == models.PaymentOrderStatusEnum.CANCELLED:
+                raise ValueError('作废状态的付款单无法再次审批')
+            locked.status = models.PaymentOrderStatusEnum.APPROVED
+            locked.save(update_fields=['status', 'updated_at'])
+            BalanceService.adjust_supplier_balance(
+                merchant=locked.merchant,
+                supplier=locked.supplier,
+                delta=-locked.amount,
+            )
+        locked.refresh_from_db(fields=['status', 'updated_at'])
+        return locked
 
-    order.refresh_from_db(fields=['status', 'updated_at'])
-    return order
+    if order.status == models.PaymentOrderStatusEnum.APPROVED:
+        raise ValueError('已审批的付款单无法作废')
+
+    with transaction.atomic():
+        locked = models.PaymentOrder.objects.select_for_update().get(id=order.id)
+        locked.status = models.PaymentOrderStatusEnum.CANCELLED
+        locked.save(update_fields=['status', 'updated_at'])
+
+    locked.refresh_from_db(fields=['status', 'updated_at'])
+    return locked
 
 
 def review_receipt_order(
@@ -322,12 +407,37 @@ def review_receipt_order(
     if order.status == target_status:
         return order
 
+    if target_status == models.ReceiptOrderStatusEnum.APPROVED:
+        if order.status == models.ReceiptOrderStatusEnum.CANCELLED:
+            raise ValueError('作废状态的收款单无法再次审批')
         with transaction.atomic():
-        order.status = target_status
-        order.save(update_fields=['status', 'updated_at'])
+            locked = models.ReceiptOrder.objects.select_related(
+                'merchant', 'customer'
+            ).select_for_update().get(id=order.id)
+            if locked.status == models.ReceiptOrderStatusEnum.APPROVED:
+                return locked
+            if locked.status == models.ReceiptOrderStatusEnum.CANCELLED:
+                raise ValueError('作废状态的收款单无法再次审批')
+            locked.status = models.ReceiptOrderStatusEnum.APPROVED
+            locked.save(update_fields=['status', 'updated_at'])
+            BalanceService.adjust_customer_balance(
+                merchant=locked.merchant,
+                customer=locked.customer,
+                delta=-locked.amount,
+            )
+        locked.refresh_from_db(fields=['status', 'updated_at'])
+        return locked
 
-    order.refresh_from_db(fields=['status', 'updated_at'])
-    return order
+    if order.status == models.ReceiptOrderStatusEnum.APPROVED:
+        raise ValueError('已审批的收款单无法作废')
+
+    with transaction.atomic():
+        locked = models.ReceiptOrder.objects.select_for_update().get(id=order.id)
+        locked.status = models.ReceiptOrderStatusEnum.CANCELLED
+        locked.save(update_fields=['status', 'updated_at'])
+
+    locked.refresh_from_db(fields=['status', 'updated_at'])
+    return locked
 
 
 def _normalize_order_items(
@@ -449,80 +559,112 @@ def _approve_purchase_order(
     purchase_order: models.PurchaseOrder,
     reviewed_by,
 ) -> models.PurchaseOrder:
-    stock_flow_items = _build_stock_flow_items_from_order(purchase_order)
-
     with transaction.atomic():
-        purchase_order.status = models.PurchaseOrderStatusEnum.APPROVED
-        purchase_order.save(update_fields=['status', 'updated_at'])
+        locked_order = models.PurchaseOrder.objects.select_related(
+            'merchant', 'warehouse', 'supplier'
+        ).prefetch_related('items').select_for_update().get(id=purchase_order.id)
+
+        if locked_order.status == models.PurchaseOrderStatusEnum.APPROVED:
+            return locked_order
+        if locked_order.status == models.PurchaseOrderStatusEnum.CANCELLED:
+            raise ValueError('作废状态的采购单无法再次审批')
+
+        stock_flow_items = _build_stock_flow_items_from_order(locked_order)
+
+        locked_order.status = models.PurchaseOrderStatusEnum.APPROVED
+        locked_order.save(update_fields=['status', 'updated_at'])
+        BalanceService.adjust_supplier_balance(
+            merchant=locked_order.merchant,
+            supplier=locked_order.supplier,
+            delta=locked_order.get_total_amount(),
+        )
 
     created_by_id = getattr(reviewed_by, 'id', None)
-    if _auto_stock_task_enabled(purchase_order.merchant):
-        logger.info('审批通过采购单 %s，触发入库任务', purchase_order.id)
+    if _auto_stock_task_enabled(locked_order.merchant):
+        logger.info('审批通过采购单 %s，触发入库任务', locked_order.id)
         create_purchase_order_stock_entries.delay(
-            purchase_order_id=purchase_order.id,
-            warehouse_id=purchase_order.warehouse_id,
+            purchase_order_id=locked_order.id,
+            warehouse_id=locked_order.warehouse_id,
             items=stock_flow_items,
             created_by_id=created_by_id,
         )
 
-    purchase_order.refresh_from_db(fields=['status', 'updated_at'])
-    return purchase_order
+    locked_order.refresh_from_db(fields=['status', 'updated_at'])
+    return locked_order
 
 
 def _cancel_purchase_order(purchase_order: models.PurchaseOrder) -> models.PurchaseOrder:
+    with transaction.atomic():
+        locked = models.PurchaseOrder.objects.select_related('merchant').select_for_update().get(id=purchase_order.id)
+        if locked.status == models.PurchaseOrderStatusEnum.APPROVED:
+            raise ValueError('已审批的采购单无法作废')
         if _order_has_stock_records(
-        merchant_id=purchase_order.merchant_id,
+            merchant_id=locked.merchant_id,
             source_type=stock_models.StockChangeSourceEnum.PURCHASE,
-        source_id=purchase_order.id,
+            source_id=locked.id,
         ):
             raise ValueError('采购单已生成出入库记录，无法作废')
-
-    with transaction.atomic():
-        purchase_order.status = models.PurchaseOrderStatusEnum.CANCELLED
-        purchase_order.save(update_fields=['status', 'updated_at'])
-
-    purchase_order.refresh_from_db(fields=['status', 'updated_at'])
-    return purchase_order
+        locked.status = models.PurchaseOrderStatusEnum.CANCELLED
+        locked.save(update_fields=['status', 'updated_at'])
+    locked.refresh_from_db(fields=['status', 'updated_at'])
+    return locked
 
 
 def _approve_sales_order(
     sales_order: models.SalesOrder,
     reviewed_by,
 ) -> models.SalesOrder:
-    stock_flow_items = _build_stock_flow_items_from_order(sales_order)
-
     with transaction.atomic():
-        sales_order.status = models.SalesOrderStatusEnum.APPROVED
-        sales_order.save(update_fields=['status', 'updated_at'])
+        locked_order = models.SalesOrder.objects.select_related(
+            'merchant', 'warehouse', 'customer'
+        ).prefetch_related('items').select_for_update().get(id=sales_order.id)
+
+        if locked_order.status == models.SalesOrderStatusEnum.APPROVED:
+            return locked_order
+        if locked_order.status == models.SalesOrderStatusEnum.CANCELLED:
+            raise ValueError('作废状态的销售单无法再次审批')
+
+        stock_flow_items = _build_stock_flow_items_from_order(locked_order)
+
+        locked_order.status = models.SalesOrderStatusEnum.APPROVED
+        locked_order.save(update_fields=['status', 'updated_at'])
+        BalanceService.adjust_customer_balance(
+            merchant=locked_order.merchant,
+            customer=locked_order.customer,
+            delta=locked_order.get_total_amount(),
+        )
 
     created_by_id = getattr(reviewed_by, 'id', None)
-    if _auto_stock_task_enabled(sales_order.merchant):
-        logger.info('审批通过销售单 %s，触发出库任务', sales_order.id)
+    if _auto_stock_task_enabled(locked_order.merchant):
+        logger.info('审批通过销售单 %s，触发出库任务', locked_order.id)
         create_sales_order_stock_entries.delay(
-            sales_order_id=sales_order.id,
-            warehouse_id=sales_order.warehouse_id,
+            sales_order_id=locked_order.id,
+            warehouse_id=locked_order.warehouse_id,
             items=stock_flow_items,
             created_by_id=created_by_id,
         )
 
-    sales_order.refresh_from_db(fields=['status', 'updated_at'])
-    return sales_order
+    locked_order.refresh_from_db(fields=['status', 'updated_at'])
+    return locked_order
 
 
 def _cancel_sales_order(sales_order: models.SalesOrder) -> models.SalesOrder:
+    with transaction.atomic():
+        locked = models.SalesOrder.objects.select_related('merchant').select_for_update().get(id=sales_order.id)
+        if locked.status == models.SalesOrderStatusEnum.APPROVED:
+            raise ValueError('已审批的销售单无法作废')
         if _order_has_stock_records(
-        merchant_id=sales_order.merchant_id,
+            merchant_id=locked.merchant_id,
             source_type=stock_models.StockChangeSourceEnum.SALES,
-        source_id=sales_order.id,
+            source_id=locked.id,
         ):
             raise ValueError('销售单已生成出入库记录，无法作废')
 
-    with transaction.atomic():
-        sales_order.status = models.SalesOrderStatusEnum.CANCELLED
-        sales_order.save(update_fields=['status', 'updated_at'])
+        locked.status = models.SalesOrderStatusEnum.CANCELLED
+        locked.save(update_fields=['status', 'updated_at'])
 
-    sales_order.refresh_from_db(fields=['status', 'updated_at'])
-    return sales_order
+    locked.refresh_from_db(fields=['status', 'updated_at'])
+    return locked
 
 
 def create_purchase_order_stock_entries_sync(

business/tests.py

@@ -1,7 +1,10 @@
 from typing import List, Dict, Any
+from decimal import Decimal
+from concurrent.futures import ThreadPoolExecutor
 
 from django.contrib.auth import get_user_model
-from django.test import TestCase, override_settings
+from django.test import TestCase, TransactionTestCase, override_settings
+from django.db import connections
 from django.utils import timezone
 from unittest.mock import patch, MagicMock
 
@@ -171,6 +174,11 @@ class PurchaseOrderServiceTestCase(TestCase):
             items=[{'product_id': self.product.id, 'quantities': ['10', '5']}],
             created_by_id=self.user.id,
         )
+        balance = business_models.SupplierBalance.objects.get(
+            merchant=self.merchant,
+            supplier=self.supplier,
+        )
+        self.assertEqual(balance.balance, purchase_order.get_total_amount())
 
     def test_create_purchase_order_without_items_raises(self):
         with self.assertRaises(ValueError):
@@ -324,6 +332,11 @@ class SalesOrderServiceTestCase(TestCase):
             items=[{'product_id': self.product.id, 'quantities': ['6', '4']}],
             created_by_id=self.user.id,
         )
+        balance = business_models.CustomerBalance.objects.get(
+            merchant=self.merchant,
+            customer=self.customer,
+        )
+        self.assertEqual(balance.balance, sales_order.get_total_amount())
 
     def test_sales_order_cancel_blocked_after_stock_created(self):
         sales_order = services.create_sales_order(
@@ -392,7 +405,6 @@ class SalesOrderServiceTestCase(TestCase):
                 created_by=self.user,
             )
 
-
 class PaymentReceiptServiceTestCase(TestCase):
     def setUp(self):
         (
@@ -426,6 +438,17 @@ class PaymentReceiptServiceTestCase(TestCase):
             reviewed_by=self.operator,
         )
         self.assertEqual(reviewed.status, business_models.PaymentOrderStatusEnum.APPROVED)
+        balance = business_models.SupplierBalance.objects.get(
+            merchant=self.merchant,
+            supplier=self.supplier,
+        )
+        self.assertEqual(balance.balance, Decimal('-120.50'))
+        with self.assertRaises(ValueError):
+            services.review_payment_order(
+                payment_order=order,
+                target_status=business_models.PaymentOrderStatusEnum.CANCELLED,
+                reviewed_by=self.operator,
+            )
 
     def test_create_receipt_order_and_cancel(self):
         order = services.create_receipt_order(
@@ -472,6 +495,11 @@ class PaymentReceiptServiceTestCase(TestCase):
             reviewed_by=self.operator,
         )
         self.assertEqual(reviewed_again.status, business_models.ReceiptOrderStatusEnum.APPROVED)
+        balance = business_models.CustomerBalance.objects.get(
+            merchant=self.merchant,
+            customer=self.customer,
+        )
+        self.assertEqual(balance.balance, Decimal('-10'))
 
 
 class PurchaseOrderStockServiceTestCase(TestCase):
@@ -593,6 +621,58 @@ class SalesOrderStockServiceTestCase(TestCase):
         self.assertEqual(payload['stock_change_record_id'], 987)
 
 
+class SalesOrderConcurrencyTestCase(TransactionTestCase):
+    reset_sequences = True
+
+    def setUp(self):
+        (
+            self.merchant,
+            self.customer,
+            self.warehouse_strict,
+            self.warehouse_relaxed,
+            self.warehouse_strict_out,
+            self.product,
+            self.operator,
+        ) = create_sales_fixtures()
+        basic_models.MerchantSetting.objects.filter(
+            merchant=self.merchant,
+            key=basic_models.MerchantSettingKeyEnum.AUTO_CREATE_STOCK_CHANGE_TASKS,
+        ).update(val_bool=False)
+        User = get_user_model()
+        self.user = User.objects.create_user(username='concurrent', password='pass123')
+        self.sales_order = services.create_sales_order(
+            merchant=self.merchant,
+            customer=self.customer,
+            order_date=timezone.now().date(),
+            warehouse=self.warehouse_strict,
+            operator=self.operator,
+            items=[{'product_id': self.product.id, 'numbers': [5], 'price': '12', 'unit': '米'}],
+            created_by=self.user,
+        )
+
+    def test_concurrent_sales_order_approval_updates_balance_once(self):
+        def approve():
+            services.review_sales_order(
+                sales_order_id=self.sales_order.id,
+                target_status=business_models.SalesOrderStatusEnum.APPROVED,
+                reviewed_by=self.user,
+            )
+
+        with ThreadPoolExecutor(max_workers=2) as executor:
+            futures = [executor.submit(approve) for _ in range(2)]
+            for future in futures:
+                future.result()
+
+        balance = business_models.CustomerBalance.objects.get(
+            merchant=self.merchant,
+            customer=self.customer,
+        )
+        self.assertEqual(balance.balance, self.sales_order.get_total_amount())
+
+    def tearDown(self):
+        connections.close_all()
+
+
 @override_settings(
     CELERY_TASK_ALWAYS_EAGER=True,
     CELERY_TASK_EAGER_PROPAGATES=True,

docs/business_api_reference.md

@@ -0,0 +1,213 @@
+# Business 模块 API 汇总
+
+本文件汇集 `business` 模块及其在 `api_v1` 下的所有接口，前端只需参考本页即可完成对接。所有接口均位于 `/api/v1/`，除明确说明外均需用户已登录且具备员工身份。
+
+---
+
+## 1. 通用约定
+
+| 项 | 说明 |
+|----|------|
+| 认证 | Session / Token（与项目统一）。用户必须关联 `Employee` 且属于目标 `Merchant`。 |
+| 多租户 | `request.user.employee.merchant` 自动限定数据范围，接口内部已校验，无需额外参数。 |
+| 分页 | 列表接口使用 `limit` / `offset`，默认 `limit=20`，最大 `100`。 |
+| 状态枚举 | `1=PENDING`、`2=APPROVED`、`3=CANCELLED`。审批接口通过 `action=approve/cancel` 修改状态。 |
+| 金额字段 | 字符串形式的十进制数（例如 `"123.45"`），与后端 `Decimal` 精度一致。 |
+| items 结构 | 受仓库模式影响：<br>• 严进/严进严出：`numbers: [int,…]` 表示条数明细<br>• 宽进宽出：`quantity` + `num_of_rolls`<br>• 严出：`consume_detail_ids: [detail_id,…]` |
+| 审批副作用 | 采购/销售审批通过后根据商户设置触发 Celery 入/出库任务；付款/收款审批通过将同步写入余额表。 |
+
+错误响应统一为 `{"error": "代码", "message": "描述"}`，字段可能因场景扩展（如 `record_id`、`fields` 等）。
+
+---
+
+## 2. 采购单（PurchaseOrder）
+
+| API | 方法 | 描述 |
+|-----|------|------|
+| `/purchase-orders/` | GET | 分页列表。 |
+| `/purchase-orders/` | POST | 创建采购单。 |
+| `/purchase-orders/<id>/review/` | POST | 审批或作废。 |
+
+### 2.1 创建请求体
+
+```json
+{
+  "supplier": 12,
+  "warehouse": 8,
+  "order_date": "2025-11-30",
+  "items": [
+    {
+      "product_id": 1001,
+      "numbers": [30, 25],
+      "price": "12.50",
+      "unit": "米"
+    }
+  ],
+  "remarks": "可选"
+}
+```
+
+宽进仓将 `numbers` 换为 `quantity` + `num_of_rolls`。至少 1 条明细，否则返回 400。
+
+### 2.2 审批
+
+`POST /purchase-orders/<id>/review/`，请求体 `{"action": "approve"}` 或 `{"action": "cancel"}`。
+
+- `approve`：在事务内将状态置为 `APPROVED`、写入供应商余额（正向金额），并在商户开启自动任务时触发 `create_purchase_order_stock_entries`。
+- `cancel`：若已存在 `StockChangeRecord`（source=`PURCHASE`），返回 400；否则置为 `CANCELLED`。
+
+成功返回最新的采购单序列化（含 `items`、`total_amount`、`status_name` 等）。
+
+---
+
+## 3. 销售单（SalesOrder）
+
+| API | 方法 | 描述 |
+|-----|------|------|
+| `/sales-orders/` | GET | 分页列表。 |
+| `/sales-orders/` | POST | 创建销售单。 |
+| `/sales-orders/<id>/review/` | POST | 审批或作废。 |
+
+### 3.1 创建请求体
+
+```json
+{
+  "customer": 6,
+  "warehouse": 3,
+  "order_date": "2025-11-30",
+  "items": [
+    {
+      "product_id": 1001,
+      "numbers": [20, 18],
+      "price": "18.80",
+      "unit": "米"
+    }
+  ],
+  "remarks": ""
+}
+```
+
+仓库为严出（`RESTRICT_IN_OUT`）时必须改用：
+
+```json
+{
+  "product_id": 1001,
+  "consume_detail_ids": [321, 322],
+  "quantity": 200,
+  "price": "20",
+  "unit": "米"
+}
+```
+
+### 3.2 审批
+
+与采购单一致，但方向为出库：
+
+- `approve`：写入客户余额（正向欠款），若商户配置自动出库则触发 `create_sales_order_stock_entries`。
+- `cancel`：如果已存在 `StockChangeRecord`（source=`SALES`）则拒绝。
+
+---
+
+## 4. 付款单（PaymentOrder）
+
+| API | 方法 | 描述 |
+|-----|------|------|
+| `/payment-orders/` | GET | 分页列表。 |
+| `/payment-orders/` | POST | 创建付款单。 |
+| `/payment-orders/<id>/review/` | POST | 审批或作废。 |
+
+### 4.1 创建请求体
+
+```json
+{
+  "supplier": 12,
+  "payment_date": "2025-11-30",
+  "amount": "5000.00",
+  "remarks": ""
+}
+```
+
+`amount` 必须大于 0。返回 201 + 创建的记录。
+
+### 4.2 审批逻辑
+
+- `approve`：在事务内锁定单据，防止重复审批；状态改为 `APPROVED`，并将供应商余额 **减少** 对应金额。
+- `cancel`：仅允许从 `PENDING` 作废，且若已审批则返回 400。
+
+---
+
+## 5. 收款单（ReceiptOrder）
+
+| API | 方法 | 描述 |
+|-----|------|------|
+| `/receipt-orders/` | GET | 列表。 |
+| `/receipt-orders/` | POST | 创建收款单。 |
+| `/receipt-orders/<id>/review/` | POST | 审批或作废。 |
+
+### 5.1 创建
+
+```json
+{
+  "customer": 6,
+  "receipt_date": "2025-11-30",
+  "amount": "3200.00",
+  "remarks": ""
+}
+```
+
+### 5.2 审批
+
+- `approve`：状态改为 `APPROVED`，客户余额 **减少** 对应金额（冲减欠款）。若已取消则拒绝再次审批。
+- `cancel`：仅允许从 `PENDING` 作废；当单据已审批时返回 400。
+
+---
+
+## 6. 余额表 / 对账接口
+
+余额数据来自 `SupplierBalance` / `CustomerBalance` 表，所有审批通过的单据均在事务内写入，保证与业务状态一致。
+
+### 6.1 客户余额
+
+| API | 方法 | 描述 |
+|-----|------|------|
+| `/customers/<id>/balance/` | GET | 查询指定客户应收余额。 |
+
+响应示例：
+
+```json
+{
+  "customer": 6,
+  "customer_name": "杭州零售商",
+  "balance": "3200.00"
+}
+```
+
+- 正数表示客户仍欠款；负数表示已收超额。
+- 若客户无记录返回 `"0"`。
+
+### 6.2 供应商余额
+
+目前仅内部使用（审批写入），如需对外查询可在此基础上新增 `/suppliers/<id>/balance/`，逻辑与客户一致：采购单审批增加余额、付款单审批减少余额。
+
+---
+
+## 7. 错误码与常见响应
+
+| 场景 | HTTP | 返回 |
+|------|------|------|
+| 未登录 / 认证失败 | 401 | `{"detail": "Authentication credentials were not provided."}` |
+| 非本商户数据 | 403 | `{"error": "forbidden", "message": "无权限访问"}` |
+| 单据不存在 | 404 | `{"error": "purchase_order_not_found"}` 等 |
+| 审批非法状态 | 400 | 例如 `{"error": "purchase_order_has_stock_records"}`、`{"error": "receipt_order_already_approved"}` |
+| 余额功能未实现 | 501 | 仅限未来拓展，例如库存红冲尚未开放 |
+
+---
+
+## 8. 参考文档
+
+- `docs/purchase_order_approval_and_red_flush.md`：采购单审批及未来红冲方案。
+- `docs/sales_order_approval_and_red_flush.md`：销售单审批与严出模式说明。
+- `docs/payment_receipt_workflow.md`：资金类单据与余额表写入逻辑。
+
+本汇总会随着业务扩展同步更新，如需新增接口请补充到此文件以保持前端“单文档”体验。***
+

docs/payment_receipt_workflow.md

@@ -5,6 +5,7 @@
 - `ReceiptOrder`：针对客户的资金收入单据，审批通过后代表“确认收款”。
 - 两者均位于 `business` 模块，API 路径分别为 `/api/v1/payment-orders/`、`/api/v1/receipt-orders/`。
 - 与采购/销售相比，不涉及产品与库存，仅维护资金方向、对方主体、金额与状态。
+- 审批通过会同步更新供应商/客户余额表（`SupplierBalance` / `CustomerBalance`），提供 O(1) 的欠款查询。
 
 ## 2. 创建流程
 | 字段 | 付款单 | 收款单 |

docs/purchase_order_approval_and_red_flush.md

@@ -4,7 +4,7 @@
 
 - 采购单在创建时默认进入 `PENDING`（审批中）状态，不再立即创建出入库记录。
 - `business.services.review_purchase_order` 统一处理审批通过 (`APPROVED`) 与作废 (`CANCELLED`) 的业务规则。
-- `api_v1/business/purchase/views.py` 暴露 `POST /api/v1/purchase-orders/<id>/review/` 接口作为唯一入口，便于前端、自动化流程和第三方系统统一调用。
+- `api_v1/views/business/purchase/views.py` 暴露 `POST /api/v1/purchase-orders/<id>/review/` 接口作为唯一入口，便于前端、自动化流程和第三方系统统一调用。
 
 ## 2. 审批流程总览
 

docs/sales_order_approval_and_red_flush.md

@@ -4,7 +4,7 @@
 
 - 销售单在创建时同样进入 `PENDING` 状态，审批通过后才会触发出库流程。
 - `business.services.review_sales_order` 统一处理审批通过 (`APPROVED`) 与作废 (`CANCELLED`) 的业务规则。
-- `api_v1/business/sales/views.py` 暴露 `POST /api/v1/sales-orders/<id>/review/` 接口，供前端、自动化和第三方系统一致调用。
+- `api_v1/views/business/sales/views.py` 暴露 `POST /api/v1/sales-orders/<id>/review/` 接口，供前端、自动化和第三方系统一致调用。
 
 ## 2. 审批流程总览