feat(payment): balance recharge multiplier and refund amount separation

- Add balance_recharge_multiplier system setting (e.g. 1.2 = charge 100 get 120)
- Separate order_amount (credited balance) from pay_amount (actual payment)
- Refund calculates gateway amount proportionally from pay_amount
- Frontend shows both amounts in order details, payment status, refund dialog
- Admin settings UI for configuring recharge multiplier

backend/internal/handler/admin/setting_handler.go

@@ -188,6 +188,7 @@ func (h *SettingHandler) GetSettings(c *gin.Context) {
 		PaymentMaxPendingOrders:              paymentCfg.MaxPendingOrders,
 		PaymentEnabledTypes:                  paymentCfg.EnabledTypes,
 		PaymentBalanceDisabled:               paymentCfg.BalanceDisabled,
+		PaymentBalanceRechargeMultiplier:     paymentCfg.BalanceRechargeMultiplier,
 		PaymentLoadBalanceStrat:              paymentCfg.LoadBalanceStrategy,
 		PaymentProductNamePrefix:             paymentCfg.ProductNamePrefix,
 		PaymentProductNameSuffix:             paymentCfg.ProductNameSuffix,
@@ -323,9 +324,10 @@ type UpdateSettingsRequest struct {
 	PaymentDailyLimit        *float64 `json:"payment_daily_limit"`
 	PaymentOrderTimeoutMin   *int     `json:"payment_order_timeout_minutes"`
 	PaymentMaxPendingOrders  *int     `json:"payment_max_pending_orders"`
-	PaymentEnabledTypes      []string `json:"payment_enabled_types"`
-	PaymentBalanceDisabled   *bool    `json:"payment_balance_disabled"`
-	PaymentLoadBalanceStrat  *string  `json:"payment_load_balance_strategy"`
+	PaymentEnabledTypes              []string `json:"payment_enabled_types"`
+	PaymentBalanceDisabled           *bool    `json:"payment_balance_disabled"`
+	PaymentBalanceRechargeMultiplier *float64 `json:"payment_balance_recharge_multiplier"`
+	PaymentLoadBalanceStrat          *string  `json:"payment_load_balance_strategy"`
 	PaymentProductNamePrefix *string  `json:"payment_product_name_prefix"`
 	PaymentProductNameSuffix *string  `json:"payment_product_name_suffix"`
 	PaymentHelpImageURL      *string  `json:"payment_help_image_url"`
@@ -934,24 +936,25 @@ func (h *SettingHandler) UpdateSettings(c *gin.Context) {
 	// Skip if no payment fields were provided (prevents accidental wipe).
 	if h.paymentConfigService != nil && hasPaymentFields(req) {
 		paymentReq := service.UpdatePaymentConfigRequest{
-			Enabled:                req.PaymentEnabled,
-			MinAmount:              req.PaymentMinAmount,
-			MaxAmount:              req.PaymentMaxAmount,
-			DailyLimit:             req.PaymentDailyLimit,
-			OrderTimeoutMin:        req.PaymentOrderTimeoutMin,
-			MaxPendingOrders:       req.PaymentMaxPendingOrders,
-			EnabledTypes:           req.PaymentEnabledTypes,
-			BalanceDisabled:        req.PaymentBalanceDisabled,
-			LoadBalanceStrategy:    req.PaymentLoadBalanceStrat,
-			ProductNamePrefix:      req.PaymentProductNamePrefix,
-			ProductNameSuffix:      req.PaymentProductNameSuffix,
-			HelpImageURL:           req.PaymentHelpImageURL,
-			HelpText:               req.PaymentHelpText,
-			CancelRateLimitEnabled: req.PaymentCancelRateLimitEnabled,
-			CancelRateLimitMax:     req.PaymentCancelRateLimitMax,
-			CancelRateLimitWindow:  req.PaymentCancelRateLimitWindow,
-			CancelRateLimitUnit:    req.PaymentCancelRateLimitUnit,
-			CancelRateLimitMode:    req.PaymentCancelRateLimitMode,
+			Enabled:                   req.PaymentEnabled,
+			MinAmount:                 req.PaymentMinAmount,
+			MaxAmount:                 req.PaymentMaxAmount,
+			DailyLimit:                req.PaymentDailyLimit,
+			OrderTimeoutMin:           req.PaymentOrderTimeoutMin,
+			MaxPendingOrders:          req.PaymentMaxPendingOrders,
+			EnabledTypes:              req.PaymentEnabledTypes,
+			BalanceDisabled:           req.PaymentBalanceDisabled,
+			BalanceRechargeMultiplier: req.PaymentBalanceRechargeMultiplier,
+			LoadBalanceStrategy:       req.PaymentLoadBalanceStrat,
+			ProductNamePrefix:         req.PaymentProductNamePrefix,
+			ProductNameSuffix:         req.PaymentProductNameSuffix,
+			HelpImageURL:              req.PaymentHelpImageURL,
+			HelpText:                  req.PaymentHelpText,
+			CancelRateLimitEnabled:    req.PaymentCancelRateLimitEnabled,
+			CancelRateLimitMax:        req.PaymentCancelRateLimitMax,
+			CancelRateLimitWindow:     req.PaymentCancelRateLimitWindow,
+			CancelRateLimitUnit:       req.PaymentCancelRateLimitUnit,
+			CancelRateLimitMode:       req.PaymentCancelRateLimitMode,
 		}
 		if err := h.paymentConfigService.UpdatePaymentConfig(c.Request.Context(), paymentReq); err != nil {
 			response.ErrorFrom(c, err)
@@ -1082,6 +1085,7 @@ func (h *SettingHandler) UpdateSettings(c *gin.Context) {
 		PaymentMaxPendingOrders:              updatedPaymentCfg.MaxPendingOrders,
 		PaymentEnabledTypes:                  updatedPaymentCfg.EnabledTypes,
 		PaymentBalanceDisabled:               updatedPaymentCfg.BalanceDisabled,
+		PaymentBalanceRechargeMultiplier:     updatedPaymentCfg.BalanceRechargeMultiplier,
 		PaymentLoadBalanceStrat:              updatedPaymentCfg.LoadBalanceStrategy,
 		PaymentProductNamePrefix:             updatedPaymentCfg.ProductNamePrefix,
 		PaymentProductNameSuffix:             updatedPaymentCfg.ProductNameSuffix,
@@ -1101,6 +1105,7 @@ func hasPaymentFields(req UpdateSettingsRequest) bool {
 		req.PaymentMaxAmount != nil || req.PaymentDailyLimit != nil ||
 		req.PaymentOrderTimeoutMin != nil || req.PaymentMaxPendingOrders != nil ||
 		req.PaymentEnabledTypes != nil || req.PaymentBalanceDisabled != nil ||
+		req.PaymentBalanceRechargeMultiplier != nil ||
 		req.PaymentLoadBalanceStrat != nil || req.PaymentProductNamePrefix != nil ||
 		req.PaymentProductNameSuffix != nil || req.PaymentHelpImageURL != nil ||
 		req.PaymentHelpText != nil || req.PaymentCancelRateLimitEnabled != nil ||

backend/internal/handler/dto/settings.go

@@ -134,9 +134,10 @@ type SystemSettings struct {
 	PaymentDailyLimit        float64  `json:"payment_daily_limit"`
 	PaymentOrderTimeoutMin   int      `json:"payment_order_timeout_minutes"`
 	PaymentMaxPendingOrders  int      `json:"payment_max_pending_orders"`
-	PaymentEnabledTypes      []string `json:"payment_enabled_types"`
-	PaymentBalanceDisabled   bool     `json:"payment_balance_disabled"`
-	PaymentLoadBalanceStrat  string   `json:"payment_load_balance_strategy"`
+	PaymentEnabledTypes              []string `json:"payment_enabled_types"`
+	PaymentBalanceDisabled           bool     `json:"payment_balance_disabled"`
+	PaymentBalanceRechargeMultiplier float64  `json:"payment_balance_recharge_multiplier"`
+	PaymentLoadBalanceStrat          string   `json:"payment_load_balance_strategy"`
 	PaymentProductNamePrefix string   `json:"payment_product_name_prefix"`
 	PaymentProductNameSuffix string   `json:"payment_product_name_suffix"`
 	PaymentHelpImageURL      string   `json:"payment_help_image_url"`

backend/internal/handler/payment_handler.go

@@ -126,26 +126,28 @@ func (h *PaymentHandler) GetCheckoutInfo(c *gin.Context) {
 	}
 
 	response.Success(c, checkoutInfoResponse{
-		Methods:              limitsResp.Methods,
-		GlobalMin:            limitsResp.GlobalMin,
-		GlobalMax:            limitsResp.GlobalMax,
-		Plans:                planList,
-		BalanceDisabled:      cfg.BalanceDisabled,
-		HelpText:             cfg.HelpText,
-		HelpImageURL:         cfg.HelpImageURL,
-		StripePublishableKey: cfg.StripePublishableKey,
+		Methods:                   limitsResp.Methods,
+		GlobalMin:                 limitsResp.GlobalMin,
+		GlobalMax:                 limitsResp.GlobalMax,
+		Plans:                     planList,
+		BalanceDisabled:           cfg.BalanceDisabled,
+		BalanceRechargeMultiplier: cfg.BalanceRechargeMultiplier,
+		HelpText:                  cfg.HelpText,
+		HelpImageURL:              cfg.HelpImageURL,
+		StripePublishableKey:      cfg.StripePublishableKey,
 	})
 }
 
 type checkoutInfoResponse struct {
-	Methods              map[string]service.MethodLimits `json:"methods"`
-	GlobalMin            float64                         `json:"global_min"`
-	GlobalMax            float64                         `json:"global_max"`
-	Plans                []checkoutPlan                  `json:"plans"`
-	BalanceDisabled      bool                            `json:"balance_disabled"`
-	HelpText             string                          `json:"help_text"`
-	HelpImageURL         string                          `json:"help_image_url"`
-	StripePublishableKey string                          `json:"stripe_publishable_key"`
+	Methods                   map[string]service.MethodLimits `json:"methods"`
+	GlobalMin                 float64                         `json:"global_min"`
+	GlobalMax                 float64                         `json:"global_max"`
+	Plans                     []checkoutPlan                  `json:"plans"`
+	BalanceDisabled           bool                            `json:"balance_disabled"`
+	BalanceRechargeMultiplier float64                         `json:"balance_recharge_multiplier"`
+	HelpText                  string                          `json:"help_text"`
+	HelpImageURL              string                          `json:"help_image_url"`
+	StripePublishableKey      string                          `json:"stripe_publishable_key"`
 }
 
 type checkoutPlan struct {
@@ -381,6 +383,7 @@ type PublicOrderResult struct {
 	Amount      float64 `json:"amount"`
 	PayAmount   float64 `json:"pay_amount"`
 	PaymentType string  `json:"payment_type"`
+	OrderType   string  `json:"order_type"`
 	Status      string  `json:"status"`
 }
 
@@ -404,6 +407,7 @@ func (h *PaymentHandler) VerifyOrderPublic(c *gin.Context) {
 		Amount:      order.Amount,
 		PayAmount:   order.PayAmount,
 		PaymentType: order.PaymentType,
+		OrderType:   order.OrderType,
 		Status:      order.Status,
 	})
 }

backend/internal/service/payment_amounts.go

+package service
+
+import (
+	"math"
+
+	"github.com/shopspring/decimal"
+)
+
+const defaultBalanceRechargeMultiplier = 1.0
+
+func normalizeBalanceRechargeMultiplier(multiplier float64) float64 {
+	if math.IsNaN(multiplier) || math.IsInf(multiplier, 0) || multiplier <= 0 {
+		return defaultBalanceRechargeMultiplier
+	}
+	return multiplier
+}
+
+func calculateCreditedBalance(paymentAmount, multiplier float64) float64 {
+	return decimal.NewFromFloat(paymentAmount).
+		Mul(decimal.NewFromFloat(normalizeBalanceRechargeMultiplier(multiplier))).
+		Round(2).
+		InexactFloat64()
+}
+
+func calculateGatewayRefundAmount(orderAmount, payAmount, refundAmount float64) float64 {
+	if orderAmount <= 0 || payAmount <= 0 || refundAmount <= 0 {
+		return 0
+	}
+	if math.Abs(refundAmount-orderAmount) <= amountToleranceCNY {
+		return decimal.NewFromFloat(payAmount).Round(2).InexactFloat64()
+	}
+	return decimal.NewFromFloat(payAmount).
+		Mul(decimal.NewFromFloat(refundAmount)).
+		Div(decimal.NewFromFloat(orderAmount)).
+		Round(2).
+		InexactFloat64()
+}

backend/internal/service/payment_config_service.go

@@ -3,12 +3,14 @@ package service
 import (
 	"context"
 	"fmt"
+	"math"
 	"strconv"
 	"strings"
 
 	dbent "github.com/Wei-Shaw/sub2api/ent"
 	"github.com/Wei-Shaw/sub2api/ent/paymentproviderinstance"
 	"github.com/Wei-Shaw/sub2api/internal/payment"
+	infraerrors "github.com/Wei-Shaw/sub2api/internal/pkg/errors"
 )
 
 const (
@@ -21,6 +23,7 @@ const (
 	SettingEnabledPaymentTypes = "ENABLED_PAYMENT_TYPES"
 	SettingLoadBalanceStrategy = "LOAD_BALANCE_STRATEGY"
 	SettingBalancePayDisabled  = "BALANCE_PAYMENT_DISABLED"
+	SettingBalanceRechargeMult = "BALANCE_RECHARGE_MULTIPLIER"
 	SettingProductNamePrefix   = "PRODUCT_NAME_PREFIX"
 	SettingProductNameSuffix   = "PRODUCT_NAME_SUFFIX"
 	SettingHelpImageURL        = "PAYMENT_HELP_IMAGE_URL"
@@ -46,9 +49,10 @@ type PaymentConfig struct {
 	DailyLimit           float64  `json:"daily_limit"`
 	OrderTimeoutMin      int      `json:"order_timeout_minutes"`
 	MaxPendingOrders     int      `json:"max_pending_orders"`
-	EnabledTypes         []string `json:"enabled_payment_types"`
-	BalanceDisabled      bool     `json:"balance_disabled"`
-	LoadBalanceStrategy  string   `json:"load_balance_strategy"`
+	EnabledTypes              []string `json:"enabled_payment_types"`
+	BalanceDisabled           bool     `json:"balance_disabled"`
+	BalanceRechargeMultiplier float64  `json:"balance_recharge_multiplier"`
+	LoadBalanceStrategy       string   `json:"load_balance_strategy"`
 	ProductNamePrefix    string   `json:"product_name_prefix"`
 	ProductNameSuffix    string   `json:"product_name_suffix"`
 	HelpImageURL         string   `json:"help_image_url"`
@@ -71,9 +75,10 @@ type UpdatePaymentConfigRequest struct {
 	DailyLimit          *float64 `json:"daily_limit"`
 	OrderTimeoutMin     *int     `json:"order_timeout_minutes"`
 	MaxPendingOrders    *int     `json:"max_pending_orders"`
-	EnabledTypes        []string `json:"enabled_payment_types"`
-	BalanceDisabled     *bool    `json:"balance_disabled"`
-	LoadBalanceStrategy *string  `json:"load_balance_strategy"`
+	EnabledTypes              []string `json:"enabled_payment_types"`
+	BalanceDisabled           *bool    `json:"balance_disabled"`
+	BalanceRechargeMultiplier *float64 `json:"balance_recharge_multiplier"`
+	LoadBalanceStrategy       *string  `json:"load_balance_strategy"`
 	ProductNamePrefix   *string  `json:"product_name_prefix"`
 	ProductNameSuffix   *string  `json:"product_name_suffix"`
 	HelpImageURL        *string  `json:"help_image_url"`
@@ -183,7 +188,7 @@ func (s *PaymentConfigService) GetPaymentConfig(ctx context.Context) (*PaymentCo
 	keys := []string{
 		SettingPaymentEnabled, SettingMinRechargeAmount, SettingMaxRechargeAmount,
 		SettingDailyRechargeLimit, SettingOrderTimeoutMinutes, SettingMaxPendingOrders,
-		SettingEnabledPaymentTypes, SettingBalancePayDisabled, SettingLoadBalanceStrategy,
+		SettingEnabledPaymentTypes, SettingBalancePayDisabled, SettingBalanceRechargeMult, SettingLoadBalanceStrategy,
 		SettingProductNamePrefix, SettingProductNameSuffix,
 		SettingHelpImageURL, SettingHelpText,
 		SettingCancelRateLimitOn, SettingCancelRateLimitMax,
@@ -207,8 +212,9 @@ func (s *PaymentConfigService) parsePaymentConfig(vals map[string]string) *Payme
 		DailyLimit:          pcParseFloat(vals[SettingDailyRechargeLimit], 0),
 		OrderTimeoutMin:     pcParseInt(vals[SettingOrderTimeoutMinutes], defaultOrderTimeoutMin),
 		MaxPendingOrders:    pcParseInt(vals[SettingMaxPendingOrders], defaultMaxPendingOrders),
-		BalanceDisabled:     vals[SettingBalancePayDisabled] == "true",
-		LoadBalanceStrategy: vals[SettingLoadBalanceStrategy],
+		BalanceDisabled:           vals[SettingBalancePayDisabled] == "true",
+		BalanceRechargeMultiplier: normalizeBalanceRechargeMultiplier(pcParseFloat(vals[SettingBalanceRechargeMult], defaultBalanceRechargeMultiplier)),
+		LoadBalanceStrategy:       vals[SettingLoadBalanceStrategy],
 		ProductNamePrefix:   vals[SettingProductNamePrefix],
 		ProductNameSuffix:   vals[SettingProductNameSuffix],
 		HelpImageURL:        vals[SettingHelpImageURL],
@@ -256,6 +262,11 @@ func (s *PaymentConfigService) getStripePublishableKey(ctx context.Context) stri
 // nil-check before serialisation — this is inherent to patch-style update patterns
 // and cannot be meaningfully decomposed without introducing unnecessary abstraction.
 func (s *PaymentConfigService) UpdatePaymentConfig(ctx context.Context, req UpdatePaymentConfigRequest) error {
+	if req.BalanceRechargeMultiplier != nil {
+		if math.IsNaN(*req.BalanceRechargeMultiplier) || math.IsInf(*req.BalanceRechargeMultiplier, 0) || *req.BalanceRechargeMultiplier <= 0 {
+			return infraerrors.BadRequest("INVALID_BALANCE_RECHARGE_MULTIPLIER", "balance recharge multiplier must be greater than 0")
+		}
+	}
 	m := map[string]string{
 		SettingPaymentEnabled:      formatBoolOrEmpty(req.Enabled),
 		SettingMinRechargeAmount:   formatPositiveFloat(req.MinAmount),
@@ -264,6 +275,7 @@ func (s *PaymentConfigService) UpdatePaymentConfig(ctx context.Context, req Upda
 		SettingOrderTimeoutMinutes: formatPositiveInt(req.OrderTimeoutMin),
 		SettingMaxPendingOrders:    formatPositiveInt(req.MaxPendingOrders),
 		SettingBalancePayDisabled:  formatBoolOrEmpty(req.BalanceDisabled),
+		SettingBalanceRechargeMult: formatPositiveFloat(req.BalanceRechargeMultiplier),
 		SettingLoadBalanceStrategy: derefStr(req.LoadBalanceStrategy),
 		SettingProductNamePrefix:   derefStr(req.ProductNamePrefix),
 		SettingProductNameSuffix:   derefStr(req.ProductNameSuffix),

backend/internal/service/payment_fulfillment.go

@@ -216,7 +216,11 @@ func (s *PaymentService) markCompleted(ctx context.Context, o *dbent.PaymentOrde
 	if err != nil {
 		return fmt.Errorf("mark completed: %w", err)
 	}
-	s.writeAuditLog(ctx, o.ID, auditAction, "system", map[string]any{"rechargeCode": o.RechargeCode, "amount": o.Amount})
+	s.writeAuditLog(ctx, o.ID, auditAction, "system", map[string]any{
+		"rechargeCode":   o.RechargeCode,
+		"creditedAmount": o.Amount,
+		"payAmount":      o.PayAmount,
+	})
 	return nil
 }
 

backend/internal/service/payment_order.go

@@ -43,14 +43,18 @@ func (s *PaymentService) CreateOrder(ctx context.Context, req CreateOrderRequest
 	if user.Status != payment.EntityStatusActive {
 		return nil, infraerrors.Forbidden("USER_INACTIVE", "user account is disabled")
 	}
-	amount := req.Amount
+	orderAmount := req.Amount
+	limitAmount := req.Amount
 	if plan != nil {
-		amount = plan.Price
+		orderAmount = plan.Price
+		limitAmount = plan.Price
+	} else if req.OrderType == payment.OrderTypeBalance {
+		orderAmount = calculateCreditedBalance(req.Amount, cfg.BalanceRechargeMultiplier)
 	}
 	feeRate := s.getFeeRate(req.PaymentType)
-	payAmountStr := payment.CalculatePayAmount(amount, feeRate)
+	payAmountStr := payment.CalculatePayAmount(limitAmount, feeRate)
 	payAmount, _ := strconv.ParseFloat(payAmountStr, 64)
-	order, err := s.createOrderInTx(ctx, req, user, plan, cfg, amount, feeRate, payAmount)
+	order, err := s.createOrderInTx(ctx, req, user, plan, cfg, orderAmount, limitAmount, feeRate, payAmount)
 	if err != nil {
 		return nil, err
 	}
@@ -99,7 +103,7 @@ func (s *PaymentService) validateSubOrder(ctx context.Context, req CreateOrderRe
 	return plan, nil
 }
 
-func (s *PaymentService) createOrderInTx(ctx context.Context, req CreateOrderRequest, user *User, plan *dbent.SubscriptionPlan, cfg *PaymentConfig, amount, feeRate, payAmount float64) (*dbent.PaymentOrder, error) {
+func (s *PaymentService) createOrderInTx(ctx context.Context, req CreateOrderRequest, user *User, plan *dbent.SubscriptionPlan, cfg *PaymentConfig, orderAmount, limitAmount, feeRate, payAmount float64) (*dbent.PaymentOrder, error) {
 	tx, err := s.entClient.Tx(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("begin transaction: %w", err)
@@ -108,7 +112,7 @@ func (s *PaymentService) createOrderInTx(ctx context.Context, req CreateOrderReq
 	if err := s.checkPendingLimit(ctx, tx, req.UserID, cfg.MaxPendingOrders); err != nil {
 		return nil, err
 	}
-	if err := s.checkDailyLimit(ctx, tx, req.UserID, amount, cfg.DailyLimit); err != nil {
+	if err := s.checkDailyLimit(ctx, tx, req.UserID, limitAmount, cfg.DailyLimit); err != nil {
 		return nil, err
 	}
 	tm := cfg.OrderTimeoutMin
@@ -121,7 +125,7 @@ func (s *PaymentService) createOrderInTx(ctx context.Context, req CreateOrderReq
 		SetUserEmail(user.Email).
 		SetUserName(user.Username).
 		SetNillableUserNotes(psNilIfEmpty(user.Notes)).
-		SetAmount(amount).
+		SetAmount(orderAmount).
 		SetPayAmount(payAmount).
 		SetFeeRate(feeRate).
 		SetRechargeCode("").
@@ -180,6 +184,10 @@ func (s *PaymentService) checkDailyLimit(ctx context.Context, tx *dbent.Tx, user
 	}
 	var used float64
 	for _, o := range orders {
+		if o.OrderType == payment.OrderTypeBalance {
+			used += o.PayAmount
+			continue
+		}
 		used += o.Amount
 	}
 	if used+amount > limit {
@@ -213,7 +221,13 @@ func (s *PaymentService) invokeProvider(ctx context.Context, order *dbent.Paymen
 	if err != nil {
 		return nil, fmt.Errorf("update order with payment details: %w", err)
 	}
-	s.writeAuditLog(ctx, order.ID, "ORDER_CREATED", fmt.Sprintf("user:%d", req.UserID), map[string]any{"amount": req.Amount, "paymentType": req.PaymentType, "orderType": req.OrderType})
+	s.writeAuditLog(ctx, order.ID, "ORDER_CREATED", fmt.Sprintf("user:%d", req.UserID), map[string]any{
+		"paymentAmount":  req.Amount,
+		"creditedAmount": order.Amount,
+		"payAmount":      order.PayAmount,
+		"paymentType":    req.PaymentType,
+		"orderType":      req.OrderType,
+	})
 	return &CreateOrderResponse{OrderID: order.ID, Amount: order.Amount, PayAmount: payAmount, FeeRate: order.FeeRate, Status: OrderStatusPending, PaymentType: req.PaymentType, PayURL: pr.PayURL, QRCode: pr.QRCode, ClientSecret: pr.ClientSecret, ExpiresAt: order.ExpiresAt, PaymentMode: sel.PaymentMode}, nil
 }
 

backend/internal/service/payment_refund.go

@@ -113,11 +113,7 @@ func (s *PaymentService) PrepareRefund(ctx context.Context, oid int64, amt float
 	if amt-o.Amount > amountToleranceCNY {
 		return nil, nil, infraerrors.BadRequest("REFUND_AMOUNT_EXCEEDED", "refund amount exceeds recharge")
 	}
-	// Full refund: use actual pay_amount for gateway (includes fees)
-	ga := amt
-	if math.Abs(amt-o.Amount) <= amountToleranceCNY {
-		ga = o.PayAmount
-	}
+	ga := calculateGatewayRefundAmount(o.Amount, o.PayAmount, amt)
 	rr := strings.TrimSpace(reason)
 	if rr == "" && o.RefundRequestReason != nil {
 		rr = *o.RefundRequestReason

frontend/src/api/admin/payment.ts

@@ -23,6 +23,7 @@ export interface AdminPaymentConfig {
   max_pending_orders: number
   enabled_payment_types: string[]
   balance_disabled: boolean
+  balance_recharge_multiplier: number
   load_balance_strategy: string
   product_name_prefix: string
   product_name_suffix: string
@@ -40,6 +41,7 @@ export interface UpdatePaymentConfigRequest {
   max_pending_orders?: number
   enabled_payment_types?: string[]
   balance_disabled?: boolean
+  balance_recharge_multiplier?: number
   load_balance_strategy?: string
   product_name_prefix?: string
   product_name_suffix?: string

frontend/src/api/admin/settings.ts

@@ -125,6 +125,7 @@ export interface SystemSettings {
   payment_max_pending_orders: number
   payment_enabled_types: string[]
   payment_balance_disabled: boolean
+  payment_balance_recharge_multiplier: number
   payment_load_balance_strategy: string
   payment_product_name_prefix: string
   payment_product_name_suffix: string
@@ -231,6 +232,7 @@ export interface UpdateSettingsRequest {
   payment_max_pending_orders?: number
   payment_enabled_types?: string[]
   payment_balance_disabled?: boolean
+  payment_balance_recharge_multiplier?: number
   payment_load_balance_strategy?: string
   payment_product_name_prefix?: string
   payment_product_name_suffix?: string

frontend/src/components/admin/payment/AdminOrderDetail.vue

@@ -19,11 +19,11 @@
         </div>
         <div>
           <p class="text-xs text-gray-500 dark:text-gray-400">{{ t('payment.orders.amount') }}</p>
-          <p class="text-sm font-medium text-gray-900 dark:text-white">${{ order.amount.toFixed(2) }}</p>
+          <p class="text-sm font-medium text-gray-900 dark:text-white">{{ order.order_type === 'balance' ? '$' : '¥' }}{{ order.amount.toFixed(2) }}</p>
         </div>
         <div>
           <p class="text-xs text-gray-500 dark:text-gray-400">{{ t('payment.orders.payAmount') }}</p>
-          <p class="text-sm font-medium text-gray-900 dark:text-white">${{ order.pay_amount.toFixed(2) }}</p>
+          <p class="text-sm font-medium text-gray-900 dark:text-white">¥{{ order.pay_amount.toFixed(2) }}</p>
         </div>
         <div>
           <p class="text-xs text-gray-500 dark:text-gray-400">{{ t('payment.orders.paymentMethod') }}</p>
@@ -73,7 +73,7 @@
         <div class="grid grid-cols-2 gap-2 text-sm">
           <div>
             <span class="text-red-600 dark:text-red-400">{{ t('payment.admin.refundAmount') }}:</span>
-            <span class="ml-1 font-medium text-red-700 dark:text-red-300">${{ order.refund_amount.toFixed(2) }}</span>
+            <span class="ml-1 font-medium text-red-700 dark:text-red-300">{{ order.order_type === 'balance' ? '$' : '¥' }}{{ order.refund_amount.toFixed(2) }}</span>
           </div>
           <div v-if="order.refund_reason" class="col-span-2">
             <span class="text-red-600 dark:text-red-400">{{ t('payment.admin.refundReason') }}:</span>

frontend/src/components/admin/payment/AdminOrderTable.vue

@@ -53,9 +53,9 @@
 
       <template #cell-amount="{ value, row }">
         <div class="text-sm">
-          <span class="font-medium text-gray-900 dark:text-white">${{ value.toFixed(2) }}</span>
+          <span class="font-medium text-gray-900 dark:text-white">{{ row.order_type === 'balance' ? '$' : '¥' }}{{ value.toFixed(2) }}</span>
           <span v-if="row.pay_amount !== value" class="ml-1 text-xs text-gray-500">
-            ({{ t('payment.orders.payAmount') }}: ${{ row.pay_amount.toFixed(2) }})
+            ({{ t('payment.orders.payAmount') }}: ¥{{ row.pay_amount.toFixed(2) }})
           </span>
         </div>
       </template>

frontend/src/components/admin/payment/AdminRefundDialog.vue

@@ -35,11 +35,15 @@
         </div>
         <div class="mt-1 flex justify-between text-sm">
           <span class="text-gray-500 dark:text-gray-400">{{ t('payment.orders.amount') }}</span>
-          <span class="font-medium text-gray-900 dark:text-white">${{ order?.pay_amount?.toFixed(2) }}</span>
+          <span class="font-medium text-gray-900 dark:text-white">{{ order?.order_type === 'balance' ? '$' : '¥' }}{{ order?.amount?.toFixed(2) }}</span>
+        </div>
+        <div class="mt-1 flex justify-between text-sm">
+          <span class="text-gray-500 dark:text-gray-400">{{ t('payment.orders.payAmount') }}</span>
+          <span class="font-medium text-gray-900 dark:text-white">¥{{ order?.pay_amount?.toFixed(2) }}</span>
         </div>
         <div v-if="actuallyRefunded > 0" class="mt-1 flex justify-between text-sm">
           <span class="text-gray-500 dark:text-gray-400">{{ t('payment.admin.alreadyRefunded') }}</span>
-          <span class="font-medium text-red-600 dark:text-red-400">${{ actuallyRefunded.toFixed(2) }}</span>
+          <span class="font-medium text-red-600 dark:text-red-400">{{ order?.order_type === 'balance' ? '$' : '¥' }}{{ actuallyRefunded.toFixed(2) }}</span>
         </div>
       </div>
 
@@ -66,7 +70,7 @@
           </div>
           <div class="rounded-lg bg-gray-50 p-3 text-sm dark:bg-dark-700">
             <div class="text-gray-500 dark:text-gray-400">{{ t('payment.admin.orderAmount') }}</div>
-            <div class="mt-1 font-semibold text-gray-900 dark:text-white">${{ order?.pay_amount?.toFixed(2) }}</div>
+            <div class="mt-1 font-semibold text-gray-900 dark:text-white">{{ order?.order_type === 'balance' ? '$' : '¥' }}{{ order?.amount?.toFixed(2) }}</div>
           </div>
         </div>
 
@@ -91,7 +95,7 @@
       <div>
         <label class="input-label">{{ t('payment.admin.refundAmount') }}</label>
         <div class="relative">
-          <span class="absolute left-3 top-1/2 -translate-y-1/2 text-gray-500">$</span>
+          <span class="absolute left-3 top-1/2 -translate-y-1/2 text-gray-500">{{ order?.order_type === 'balance' ? '$' : '¥' }}</span>
           <input
             v-model.number="form.amount"
             type="number"
@@ -103,7 +107,7 @@
           />
         </div>
         <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">
-          {{ t('payment.admin.maxRefundable') }}: ${{ maxRefundable.toFixed(2) }}
+          {{ t('payment.admin.maxRefundable') }}: {{ order?.order_type === 'balance' ? '$' : '¥' }}{{ maxRefundable.toFixed(2) }}
         </p>
       </div>
 
@@ -200,12 +204,12 @@ const actuallyRefunded = computed(() => {
 
 const maxRefundable = computed(() => {
   if (!props.order) return 0
-  return props.order.pay_amount - actuallyRefunded.value
+  return props.order.amount - actuallyRefunded.value
 })
 
 const balanceInsufficient = computed(() => {
   if (props.userBalance == null || !props.order) return false
-  return props.userBalance < props.order.pay_amount
+  return props.userBalance < props.order.amount
 })
 
 watch(() => props.show, (val) => {

frontend/src/components/payment/OrderTable.vue

@@ -14,8 +14,8 @@
     </template>
     <template #cell-amount="{ value, row }">
       <div class="text-sm">
-        <span class="font-medium text-gray-900 dark:text-white">${{ value.toFixed(2) }}</span>
-        <span v-if="row.pay_amount !== value" class="ml-1 text-xs text-gray-500">(${{ row.pay_amount.toFixed(2) }})</span>
+        <span class="font-medium text-gray-900 dark:text-white">{{ row.order_type === 'balance' ? '$' : '¥' }}{{ value.toFixed(2) }}</span>
+        <span v-if="row.pay_amount !== value" class="ml-1 text-xs text-gray-500">(¥{{ row.pay_amount.toFixed(2) }})</span>
       </div>
     </template>
     <template #cell-payment_type="{ value }">

frontend/src/components/payment/PaymentQRDialog.vue

@@ -45,7 +45,11 @@
           </div>
           <div class="flex justify-between">
             <span class="text-gray-500 dark:text-gray-400">{{ t('payment.orders.amount') }}</span>
-            <span class="font-medium text-gray-900 dark:text-white">${{ paidOrder.pay_amount.toFixed(2) }}</span>
+            <span class="font-medium text-gray-900 dark:text-white">{{ paidOrder.order_type === 'balance' ? '$' : '¥' }}{{ paidOrder.amount.toFixed(2) }}</span>
+          </div>
+          <div class="flex justify-between">
+            <span class="text-gray-500 dark:text-gray-400">{{ t('payment.orders.payAmount') }}</span>
+            <span class="font-medium text-gray-900 dark:text-white">¥{{ paidOrder.pay_amount.toFixed(2) }}</span>
           </div>
         </div>
       </div>

frontend/src/components/payment/PaymentStatusPanel.vue

@@ -22,7 +22,11 @@
               </div>
               <div class="flex justify-between">
                 <span class="text-gray-500 dark:text-gray-400">{{ t('payment.orders.amount') }}</span>
-                <span class="font-medium text-gray-900 dark:text-white">${{ paidOrder.pay_amount.toFixed(2) }}</span>
+                <span class="font-medium text-gray-900 dark:text-white">{{ paidOrder.order_type === 'balance' ? '$' : '¥' }}{{ paidOrder.amount.toFixed(2) }}</span>
+              </div>
+              <div class="flex justify-between">
+                <span class="text-gray-500 dark:text-gray-400">{{ t('payment.orders.payAmount') }}</span>
+                <span class="font-medium text-gray-900 dark:text-white">¥{{ paidOrder.pay_amount.toFixed(2) }}</span>
               </div>
             </div>
           </div>

frontend/src/components/payment/StripePaymentInline.vue

@@ -21,9 +21,13 @@
                 <span class="text-gray-500 dark:text-gray-400">{{ t('payment.orders.orderId') }}</span>
                 <span class="font-medium text-gray-900 dark:text-white">#{{ orderId }}</span>
               </div>
-              <div class="flex justify-between">
+              <div v-if="amount > 0" class="flex justify-between">
                 <span class="text-gray-500 dark:text-gray-400">{{ t('payment.orders.amount') }}</span>
-                <span class="font-medium text-gray-900 dark:text-white">${{ payAmount.toFixed(2) }}</span>
+                <span class="font-medium text-gray-900 dark:text-white">{{ orderType === 'balance' ? '$' : '¥' }}{{ amount.toFixed(2) }}</span>
+              </div>
+              <div class="flex justify-between">
+                <span class="text-gray-500 dark:text-gray-400">{{ t('payment.orders.payAmount') }}</span>
+                <span class="font-medium text-gray-900 dark:text-white">¥{{ payAmount.toFixed(2) }}</span>
               </div>
             </div>
           </div>
@@ -36,7 +40,7 @@
       <div class="card overflow-hidden">
         <div class="bg-gradient-to-br from-[#635bff] to-[#4f46e5] px-6 py-5 text-center">
           <p class="text-sm font-medium text-indigo-200">{{ t('payment.actualPay') }}</p>
-          <p class="mt-1 text-3xl font-bold text-white">${{ payAmount.toFixed(2) }}</p>
+          <p class="mt-1 text-3xl font-bold text-white">¥{{ payAmount.toFixed(2) }}</p>
         </div>
       </div>
       <!-- Stripe Payment Element -->
@@ -75,7 +79,9 @@ const POPUP_METHODS = new Set(['alipay', 'wechat_pay'])
 
 const props = defineProps<{
   orderId: number
+  amount: number
   clientSecret: string
+  orderType?: 'balance' | 'subscription'
   publishableKey: string
   payAmount: number
 }>()

frontend/src/i18n/locales/en.ts

@@ -4566,6 +4566,9 @@ export default {
         minAmount: 'Minimum Amount',
         maxAmount: 'Maximum Amount',
         dailyLimit: 'Daily Limit',
+        balanceRechargeMultiplier: 'Balance Recharge Multiplier',
+        balanceRechargeMultiplierHint: 'How many USD balance the user receives for each 1 CNY paid',
+        balanceRechargePreview: 'Preview: 1 CNY = {usd} USD',
         orderTimeout: 'Order Timeout',
         orderTimeoutHint: 'In minutes, minimum 1',
         maxPendingOrders: 'Max Pending Orders',
@@ -5324,6 +5327,8 @@ export default {
   payment: {
     title: 'Recharge / Subscription',
     amountLabel: 'Amount',
+    paymentAmount: 'Payment Amount',
+    creditedBalance: 'Credited Balance',
     quickAmounts: 'Quick Amounts',
     customAmount: 'Custom Amount',
     enterAmount: 'Enter amount',
@@ -5408,6 +5413,7 @@ export default {
     amountTooLow: 'Minimum amount is {min}',
     amountTooHigh: 'Maximum amount is {max}',
     amountNoMethod: 'No payment method available for this amount',
+    rechargeRatePreview: 'Current rate: 1 CNY = {usd} USD',
     refundReason: 'Refund Reason',
     refundReasonPlaceholder: 'Please describe your refund reason',
     stripeLoadFailed: 'Failed to load payment component. Please refresh and try again.',

frontend/src/i18n/locales/zh.ts

@@ -4730,6 +4730,9 @@ export default {
         minAmount: '最低金额',
         maxAmount: '最高金额',
         dailyLimit: '每日限额',
+        balanceRechargeMultiplier: '余额充值倍率',
+        balanceRechargeMultiplierHint: '用户每支付 1 CNY 可获得多少 USD 余额',
+        balanceRechargePreview: '预览：1 CNY = {usd} USD',
         orderTimeout: '订单超时时间',
         orderTimeoutHint: '单位：分钟，至少 1 分钟',
         maxPendingOrders: '最大待支付订单数',
@@ -5512,6 +5515,8 @@ export default {
   payment: {
     title: '充值/订阅',
     amountLabel: '充值金额',
+    paymentAmount: '支付金额',
+    creditedBalance: '到账余额',
     quickAmounts: '快捷金额',
     customAmount: '自定义金额',
     enterAmount: '输入金额',
@@ -5596,6 +5601,7 @@ export default {
     amountTooLow: '最低金额为 {min}',
     amountTooHigh: '最高金额为 {max}',
     amountNoMethod: '该金额没有可用的支付方式',
+    rechargeRatePreview: '当前倍率：1 CNY = {usd} USD',
     refundReason: '退款原因',
     refundReasonPlaceholder: '请描述您的退款原因',
     stripeLoadFailed: '支付组件加载失败，请刷新页面重试',

frontend/src/types/payment.ts

@@ -32,6 +32,7 @@ export interface PaymentConfig {
   max_pending_orders: number
   order_timeout_minutes: number
   balance_disabled: boolean
+  balance_recharge_multiplier: number
   enabled_payment_types: PaymentType[]
   help_image_url: string
   help_text: string
@@ -62,6 +63,7 @@ export interface CheckoutInfoResponse {
   global_max: number
   plans: SubscriptionPlan[]
   balance_disabled: boolean
+  balance_recharge_multiplier: number
   help_text: string
   help_image_url: string
   stripe_publishable_key: string
@@ -155,6 +157,7 @@ export interface CreateOrderRequest {
 
 export interface CreateOrderResult {
   order_id: number
+  amount: number
   pay_url?: string
   qr_code?: string
   client_secret?: string