实现支付商户池与微信授权配置

新增收款商户、商户池轮询、微信授权配置独立管理；三类新支付
（C端套餐购买、C端资产钱包充值、代理在线预存款充值）无条件
经商户池选择并冻结路由，无旧综合配置回退。merchant_id 为空
历史支付继续按 payment_config_id 双读。凭证版本化加载与
ID+版本缓存保证轮换一致性。删除商户池新支付创建开关及全部
引用。

internal/service/refund/approval_decision.go

@@ -62,6 +62,9 @@ func (s *Service) applyApprovedDecision(ctx context.Context, event approvalapp.T
 		if err := validateApprovedRefundAmount(approvedAmount, refund.RequestedRefundAmount, &order); err != nil {
 			return err
 		}
+		if err := s.preparePaymentRefundCredentials(ctx, tx, order.ID); err != nil {
+			return err
+		}
 		if refund.Status == model.RefundStatusPending {
 			changed = true
 			result := tx.WithContext(ctx).Model(&model.RefundRequest{}).

internal/service/refund/payment_merchant.go

@@ -0,0 +1,99 @@
+package refund
+
+import (
+	"context"
+	"strings"
+
+	"gorm.io/gorm"
+
+	merchantpayment "github.com/break/junhong_cmp_fiber/internal/application/merchantpayment"
+	"github.com/break/junhong_cmp_fiber/internal/model"
+	"github.com/break/junhong_cmp_fiber/pkg/errors"
+)
+
+// SetPaymentMerchantRuntime 注入冻结商户的当前凭证版本加载器。
+func (s *Service) SetPaymentMerchantRuntime(runtime *merchantpayment.RuntimeLoader) {
+	s.paymentMerchantRuntime = runtime
+}
+
+// preparePaymentRefundCredentials 只为既有套餐订单退款流程装载和校验支付凭证；本 Change
+// 不发起任何渠道退款请求。钱包支付和线下支付没有收款商户凭证，直接放行。
+// merchant_id 为空仅是留存期内的历史线上支付，独立 Change 清理后才可删除按
+// payment_config_id 读取的兼容路径，绝不能按当前商户池推断商户。
+func (s *Service) preparePaymentRefundCredentials(ctx context.Context, tx *gorm.DB, orderID uint) error {
+	var payment model.Payment
+	err := tx.WithContext(ctx).
+		Where("order_id = ? AND order_type = ? AND status = ?", orderID, model.PaymentOrderTypePackage, model.PaymentRecordStatusPaid).
+		Order("id DESC").
+		First(&payment).Error
+	if err != nil {
+		if err == gorm.ErrRecordNotFound {
+			return nil
+		}
+		return errors.Wrap(errors.CodeDatabaseError, err, "查询退款关联支付单失败")
+	}
+	// 钱包支付和线下支付没有收款商户凭证，不被本检查阻断。
+	if payment.PaymentMethod == model.PaymentByWallet || payment.PaymentMethod == model.PaymentByOffline {
+		return nil
+	}
+	if payment.MerchantID != nil {
+		if s.paymentMerchantRuntime == nil {
+			return errors.New(errors.CodeServiceUnavailable, "支付商户加载能力未配置")
+		}
+		merchant, loadErr := s.paymentMerchantRuntime.LoadMerchant(ctx, *payment.MerchantID)
+		if loadErr != nil {
+			return loadErr
+		}
+		return validateFrozenMerchantRefundCredentials(merchant)
+	}
+	if payment.PaymentConfigID == nil {
+		return errors.New(errors.CodeNoPaymentConfig, "历史支付单缺少支付配置")
+	}
+	var legacy model.WechatConfig
+	if err := tx.WithContext(ctx).Unscoped().First(&legacy, *payment.PaymentConfigID).Error; err != nil {
+		if err == gorm.ErrRecordNotFound {
+			return errors.New(errors.CodeNoPaymentConfig, "历史支付配置不可用")
+		}
+		return errors.Wrap(errors.CodeDatabaseError, err, "读取历史支付配置失败")
+	}
+	return nil
+}
+
+// validateFrozenMerchantRefundCredentials 只判断既有渠道流程所需凭证是否完整。
+// 当前系统没有任何渠道原路退款 Adapter，因此返回前不调用微信、支付宝或富友。
+func validateFrozenMerchantRefundCredentials(merchant *model.PaymentMerchant) error {
+	config, err := merchantpayment.MerchantConfig(merchant, nil)
+	if err != nil {
+		return err
+	}
+	switch config.ProviderType {
+	case model.ProviderTypeWechat:
+		if blank(config.WxMchID, config.WxAPIV3Key, config.WxCertContent, config.WxKeyContent, config.WxSerialNo, config.WxNotifyURL) {
+			return errors.New(errors.CodeNoPaymentConfig, "冻结微信商户退款凭证不完整")
+		}
+	case model.ProviderTypeWechatV2:
+		if blank(config.WxMchID, config.WxAPIV2Key, config.WxNotifyURL) {
+			return errors.New(errors.CodeNoPaymentConfig, "冻结微信商户退款凭证不完整")
+		}
+	case model.ProviderTypeFuiou:
+		if blank(config.FyInsCd, config.FyMchntCd, config.FyTermID, config.FyPrivateKey, config.FyPublicKey, config.FyAPIURL, config.FyNotifyURL) {
+			return errors.New(errors.CodeNoPaymentConfig, "冻结富友商户退款凭证不完整")
+		}
+	case "alipay":
+		if blank(config.AliAppID, config.AliPrivateKey, config.AliPublicKey, config.AliNotifyURL, config.AliReturnURL) {
+			return errors.New(errors.CodeNoPaymentConfig, "冻结支付宝商户退款凭证不完整")
+		}
+	default:
+		return errors.New(errors.CodeNoPaymentConfig, "冻结商户不支持现有退款流程")
+	}
+	return nil
+}
+
+func blank(values ...string) bool {
+	for _, value := range values {
+		if strings.TrimSpace(value) == "" {
+			return true
+		}
+	}
+	return false
+}

internal/service/refund/service.go

@@ -15,6 +15,7 @@ import (
 	"gorm.io/gorm"
 	"gorm.io/gorm/clause"
 
+	merchantpayment "github.com/break/junhong_cmp_fiber/internal/application/merchantpayment"
 	notificationapp "github.com/break/junhong_cmp_fiber/internal/application/notification"
 	refundapprovalapp "github.com/break/junhong_cmp_fiber/internal/application/refundapproval"
 	walletapp "github.com/break/junhong_cmp_fiber/internal/application/wallet"
@@ -56,6 +57,7 @@ type Service struct {
 	notificationOutbox          *outbox.Repository
 	auditWriter                 *audit.Writer
 	logger                      *zap.Logger
+	paymentMerchantRuntime      *merchantpayment.RuntimeLoader
 }
 
 // New 创建退款业务服务实例
@@ -355,6 +357,9 @@ func (s *Service) Approve(ctx context.Context, id uint, req *dto.ApproveRefundRe
 		if orderResult.RowsAffected == 0 {
 			return errors.New(errors.CodeInvalidStatus, "订单状态已变更，无法执行退款审批")
 		}
+		if err := s.preparePaymentRefundCredentials(ctx, tx, order.ID); err != nil {
+			return err
+		}
 
 		if err := s.refundWalletPayment(ctx, tx, refund, order, approvedAmount, userID); err != nil {
 			return err