fix: 微信退款API参数修正——refund_order正确字段(openid/order_id/refund_order_id/left_fee/refund_fee/refund_reason/req_from/env)替换错误的offerId/outTradeNo

server/src/routes/admin.js

@@ -1294,7 +1294,20 @@ router.post('/vpay/orders/:id/refund', requirePermission('orders:write'), async
       const accessToken = tokenRes.access_token
       if (!accessToken) throw new Error('获取access_token失败: ' + JSON.stringify(tokenRes))
 
-      const refundBody = JSON.stringify({ offerId: OFFER_ID, outTradeNo: order.orderNo })
+      // refund_order 正确参数（snake_case，官方文档 https://developers.weixin.qq.com/miniprogram/dev/server/API/VirtualPayment/api_refund_order.html）
+      const refundOrderId = `RF${Date.now()}${require('crypto').randomBytes(3).toString('hex').toUpperCase()}`
+      const refundFee = Math.round(order.amount * 100) // 退款金额（分）= 订单金额
+      const refundBody = JSON.stringify({
+        openid: user.openid,
+        order_id: order.orderNo,          // 商户单号（下单时的 outTradeNo）
+        refund_order_id: refundOrderId,   // 本次退款单号（8-32位）
+        left_fee: refundFee,              // 剩余可退金额（分）
+        refund_fee: refundFee,            // 本次退款金额（分），须 ≤ left_fee
+        biz_meta: JSON.stringify({ admin: req.admin.username, reason: 'user_refund' }),
+        refund_reason: 0,                 // 0=用户申请退款
+        req_from: 1,                      // 1=商户后台发起
+        env: ENV,
+      })
       const paySig = require('crypto').createHmac('sha256', APPKEY).update('/xpay/refund_order&' + refundBody).digest('hex')
 
       const wxRes = await fetch(`https://api.weixin.qq.com/xpay/refund_order?access_token=${accessToken}&pay_sig=${paySig}`, {