feat(M08-B): 补保洁微信转账回调与轮询

backend/src/payments/wechat-pay-client.ts

@@ -210,6 +210,22 @@ export class WechatPayClient {
     };
   }
 
+  async queryMerchantTransferByOutBillNo(credential: WechatPayCredential, outBillNo: string) {
+    const result = await this.apiRequest(
+      credential,
+      'GET',
+      `/v3/fund-app/mch-transfer/transfer-bills/out-bill-no/${encodeURIComponent(outBillNo)}`
+    );
+    return {
+      merchantId: stringField(result, 'mch_id'),
+      outBillNo: stringField(result, 'out_bill_no'),
+      transferBillNo: optionalStringField(result, 'transfer_bill_no'),
+      state: stringField(result, 'state'),
+      failReason: optionalStringField(result, 'fail_reason'),
+      amountCents: optionalNumberField(result, 'transfer_amount')
+    };
+  }
+
   verifyAndDecrypt(
     credential: WechatPayCredential,
     headers: WechatNotificationHeaders,
@@ -368,6 +384,11 @@ function optionalStringField(value: Record<string, unknown>, key: string) {
   return typeof field === 'string' ? field : '';
 }
 
+function optionalNumberField(value: Record<string, unknown>, key: string) {
+  const field = value[key];
+  return typeof field === 'number' ? field : 0;
+}
+
 function parseTransferReportInfos(value: unknown) {
   if (!Array.isArray(value)) return undefined;
   return value.map((item) => {