feat(trade): connect WeChat refund API and callback flow

Co-authored-by: Cursor <cursoragent@cursor.com>

server/dukang-api/src/integrations/pay/pay.interface.ts

@@ -7,6 +7,10 @@ export type PayOrderResult =
   | { mode: 'jsapi'; prepay: WechatJsapiPrepayParams }
   | { mode: 'native'; codeUrl: string; externalNo: string };
 
+export type RefundOrderResult =
+  | { mode: 'mock'; outRefundNo: string }
+  | { mode: 'wechat'; outRefundNo: string; refundId?: string; status: 'PROCESSING' | 'SUCCESS' };
+
 export interface IPayProvider {
   payOrder(
     orderId: bigint,
@@ -14,4 +18,5 @@ export interface IPayProvider {
     platform?: 'h5' | 'mini',
     payMethod?: PayMethod,
   ): Promise<PayOrderResult>;
+  refundOrder(orderId: bigint, outRefundNo: string, reason?: string): Promise<RefundOrderResult>;
 }

server/dukang-api/src/integrations/pay/pay.mock.provider.ts

@@ -1,7 +1,7 @@
 import { Injectable } from '@nestjs/common';
 import { loadAppConfig } from '@dukang/shared-types';
 import { PrismaService } from '../../common/prisma/prisma.module';
-import type { IPayProvider, PayMethod, PayOrderResult } from './pay.interface';
+import type { IPayProvider, PayMethod, PayOrderResult, RefundOrderResult } from './pay.interface';
 
 @Injectable()
 export class PayMockProvider implements IPayProvider {
@@ -27,4 +27,15 @@ export class PayMockProvider implements IPayProvider {
     }
     return { mode: 'mock', externalNo: `MOCK-${Date.now()}` };
   }
+
+  async refundOrder(
+    _orderId: bigint,
+    outRefundNo: string,
+    _reason?: string,
+  ): Promise<RefundOrderResult> {
+    if (!loadAppConfig().mockPay) {
+      throw new Error('Real WeChat refund requires PayWechatProvider');
+    }
+    return { mode: 'mock', outRefundNo };
+  }
 }

server/dukang-api/src/integrations/pay/pay.router.provider.ts

@@ -1,6 +1,6 @@
 import { Injectable } from '@nestjs/common';
 import { loadAppConfig } from '@dukang/shared-types';
-import type { IPayProvider, PayMethod, PayOrderResult } from './pay.interface';
+import type { IPayProvider, PayMethod, PayOrderResult, RefundOrderResult } from './pay.interface';
 import { PayMockProvider } from './pay.mock.provider';
 import { PayWechatProvider } from './pay.wechat.provider';
 
@@ -24,4 +24,12 @@ export class PayRouterProvider implements IPayProvider {
   ): Promise<PayOrderResult> {
     return this.resolve().payOrder(orderId, openId, platform, payMethod);
   }
+
+  refundOrder(
+    orderId: bigint,
+    outRefundNo: string,
+    reason?: string,
+  ): Promise<RefundOrderResult> {
+    return this.resolve().refundOrder(orderId, outRefundNo, reason);
+  }
 }

server/dukang-api/src/integrations/pay/pay.wechat.provider.ts

@@ -72,4 +72,40 @@ export class PayWechatProvider implements IPayProvider {
     });
     return { mode: 'jsapi', prepay };
   }
+
+  async refundOrder(
+    orderId: bigint,
+    outRefundNo: string,
+    reason?: string,
+  ) {
+    if (loadAppConfig().mockPay) {
+      return { mode: 'mock' as const, outRefundNo };
+    }
+    if (!this.wechat.isPayEnabled()) {
+      throw new Error('微信支付未配置：请关闭 MOCK_PAY 并配置 WX_MCH_ID 等商户参数');
+    }
+
+    const order = await this.prisma.order.findUnique({ where: { id: orderId } });
+    if (!order) throw new Error('订单不存在');
+
+    const amountFen = Math.round(Number(order.payAmount) * 100);
+    const notifyUrl = process.env.WX_REFUND_NOTIFY_URL ?? '';
+
+    this.logger.log(`create refund order=${order.orderNo} outRefundNo=${outRefundNo}`);
+    const result = await this.wechat.createDomesticRefund({
+      orderNo: order.orderNo,
+      transactionId: order.payExternalNo ?? undefined,
+      outRefundNo,
+      amountFen,
+      totalFen: amountFen,
+      reason,
+      notifyUrl,
+    });
+    return {
+      mode: 'wechat' as const,
+      outRefundNo: result.outRefundNo,
+      refundId: result.refundId,
+      status: result.status === 'SUCCESS' ? 'SUCCESS' as const : 'PROCESSING' as const,
+    };
+  }
 }