修复仲裁退款并新增免押额度

backend/internal/modules/order/repository.go

@@ -173,6 +173,11 @@ func (r *Repository) Create(renterID uint64, req CreateRequest) (*OrderDTO, erro
 		}
 		rentHours := internalOrderHours
 		pricing := buildOrderPricing(listing, account)
+		depositOriginalAmount := roundMoney(listing.DepositAmount)
+		paidDepositAmount, waivedDepositAmount, err := r.depositAmountsForOrder(tx, renterID, depositOriginalAmount)
+		if err != nil {
+			return err
+		}
 		order := model.RentalOrder{
 			OrderNo:                orderNo,
 			ListingID:              listing.ID,
@@ -182,7 +187,9 @@ func (r *Repository) Create(renterID uint64, req CreateRequest) (*OrderDTO, erro
 			EstimatedDurationHours: rentHours,
 			RentAmount:             pricing.RentAmount,
 			OwnerRentAmount:        pricing.OwnerRentAmount,
-			DepositAmount:          listing.DepositAmount,
+			DepositAmount:          paidDepositAmount,
+			DepositOriginalAmount:  depositOriginalAmount,
+			DepositWaivedAmount:    waivedDepositAmount,
 			PlatformFee:            pricing.PlatformFee,
 			AccountSnapshot:        snapshot,
 			Status:                 "pending_payment",
@@ -218,6 +225,43 @@ func (r *Repository) Create(renterID uint64, req CreateRequest) (*OrderDTO, erro
 	return r.FindForUser(renterID, createdID)
 }
 
+func (r *Repository) depositAmountsForOrder(tx *gorm.DB, renterID uint64, originalDeposit float64) (float64, float64, error) {
+	originalDeposit = roundMoney(originalDeposit)
+	if originalDeposit <= 0 {
+		return 0, 0, nil
+	}
+	var user model.User
+	if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).First(&user, renterID).Error; err != nil {
+		return 0, 0, err
+	}
+	used, err := activeDepositFreeUsed(tx, renterID)
+	if err != nil {
+		return 0, 0, err
+	}
+	paidDeposit, waivedDeposit := calculateDepositWaiver(originalDeposit, user.DepositFreeQuota, used)
+	return paidDeposit, waivedDeposit, nil
+}
+
+func activeDepositFreeUsed(tx *gorm.DB, renterID uint64) (float64, error) {
+	var used float64
+	err := tx.Model(&model.RentalOrder{}).
+		Where("renter_id = ? AND status NOT IN ?",
+			renterID,
+			[]string{"completed", "cancelled", "closed"},
+		).
+		Select("COALESCE(SUM(deposit_waived_amount), 0)").
+		Scan(&used).Error
+	return roundMoney(used), err
+}
+
+func calculateDepositWaiver(originalDeposit float64, quota float64, used float64) (float64, float64) {
+	originalDeposit = roundMoney(originalDeposit)
+	remaining := maxMoney(roundMoney(quota)-roundMoney(used), 0)
+	waived := minMoney(originalDeposit, remaining)
+	paid := maxMoney(originalDeposit-waived, 0)
+	return roundMoney(paid), roundMoney(waived)
+}
+
 // Pay 保留旧接口兼容，但真实付款必须走 payment 模块的渠道支付入口。
 func (r *Repository) Pay(userID uint64, orderID uint64) error {
 	return ErrChannelPaymentRequired
@@ -1424,6 +1468,8 @@ func (row orderRow) toAdminDTO() OrderDTO {
 		RentAmount:             &rentAmount,
 		OwnerRentAmount:        &ownerRentAmount,
 		DepositAmount:          row.DepositAmount,
+		DepositOriginalAmount:  effectiveDepositOriginalAmount(row.RentalOrder),
+		DepositWaivedAmount:    row.DepositWaivedAmount,
 		PlatformFee:            &platformFee,
 		AccountSnapshot:        row.AccountSnapshot,
 		Status:                 row.Status,
@@ -1454,6 +1500,13 @@ func toHandoffDTO(record model.HandoffRecord) HandoffRecordDTO {
 	}
 }
 
+func effectiveDepositOriginalAmount(order model.RentalOrder) float64 {
+	if order.DepositOriginalAmount > 0 {
+		return order.DepositOriginalAmount
+	}
+	return order.DepositAmount
+}
+
 func toCheckoutAdminDTO(checkout model.OrderCheckout) CheckoutDTO {
 	rentAmount := checkout.RentAmount
 	ownerRentAmount := checkout.OwnerRentAmount