fix(payment): convert subscription CNY pay amount

backend/internal/service/payment_fulfillment_test.go

@@ -602,8 +602,8 @@ func TestExecuteSubscriptionFulfillmentAppliesAffiliateRebate(t *testing.T) {
 		SetUserID(user.ID).
 		SetUserEmail(user.Email).
 		SetUserName(user.Username).
-		SetAmount(120).
-		SetPayAmount(120).
+		SetAmount(9.99).
+		SetPayAmount(71.36).
 		SetFeeRate(0).
 		SetRechargeCode("PAY-SUB-AFFILIATE").
 		SetOutTradeNo("sub2_subscription_affiliate").
@@ -636,7 +636,7 @@ func TestExecuteSubscriptionFulfillmentAppliesAffiliateRebate(t *testing.T) {
 	}
 	settingSvc := NewSettingService(&paymentFulfillmentSettingRepoStub{values: map[string]string{
 		SettingKeyAffiliateEnabled:           "true",
-		SettingKeyAffiliateRebateRate:        "20",
+		SettingKeyAffiliateRebateRate:        "15",
 		SettingKeyAffiliateRebateFreezeHours: "0",
 	}}, nil)
 	subRepo := newSubscriptionUserSubRepoStub()
@@ -659,7 +659,7 @@ func TestExecuteSubscriptionFulfillmentAppliesAffiliateRebate(t *testing.T) {
 	require.Len(t, affiliateRepo.accrueCalls, 1)
 	require.Equal(t, inviterID, affiliateRepo.accrueCalls[0].inviterID)
 	require.Equal(t, user.ID, affiliateRepo.accrueCalls[0].inviteeUserID)
-	require.Equal(t, 24.0, affiliateRepo.accrueCalls[0].amount)
+	require.InDelta(t, 1.4985, affiliateRepo.accrueCalls[0].amount, 0.00000001)
 	require.NotNil(t, affiliateRepo.accrueCalls[0].sourceOrderID)
 	require.Equal(t, order.ID, *affiliateRepo.accrueCalls[0].sourceOrderID)
 	require.Equal(t, 1, subRepo.createCalls)
@@ -668,8 +668,8 @@ func TestExecuteSubscriptionFulfillmentAppliesAffiliateRebate(t *testing.T) {
 		Where(paymentauditlog.OrderIDEQ(strconv.FormatInt(order.ID, 10)), paymentauditlog.ActionEQ("AFFILIATE_REBATE_APPLIED")).
 		Only(ctx)
 	require.NoError(t, err)
-	require.Contains(t, applied.Detail, `"baseAmount":120`)
-	require.Contains(t, applied.Detail, `"rebateAmount":24`)
+	require.Contains(t, applied.Detail, `"baseAmount":9.99`)
+	require.Contains(t, applied.Detail, `"rebateAmount":1.4985`)
 }
 
 func TestExecuteSubscriptionFulfillmentDoesNotDuplicateWorkAfterLegacySuccessAudit(t *testing.T) {

backend/internal/service/payment_order.go

@@ -16,6 +16,7 @@ import (
 	"github.com/Wei-Shaw/sub2api/internal/payment"
 	"github.com/Wei-Shaw/sub2api/internal/payment/provider"
 	infraerrors "github.com/Wei-Shaw/sub2api/internal/pkg/errors"
+	"github.com/shopspring/decimal"
 )
 
 // --- Order Creation ---
@@ -67,8 +68,7 @@ func (s *PaymentService) CreateOrder(ctx context.Context, req CreateOrderRequest
 			return nil, err
 		}
 	}
-	// 订阅套餐 price 是直付价，余额充值倍率只影响余额充值到账，不参与订阅 pay_amount 计算。
-	payAmountStr, payAmount, err := calculateCreateOrderPayAmount(limitAmount, feeRate, methodCurrency)
+	payAmountStr, payAmount, err := calculateCreateOrderPayAmountForOrderType(limitAmount, feeRate, methodCurrency, req.OrderType, cfg.BalanceRechargeMultiplier)
 	if err != nil {
 		return nil, err
 	}
@@ -84,7 +84,7 @@ func (s *PaymentService) CreateOrder(ctx context.Context, req CreateOrderRequest
 		selectedCurrency = paymentProviderConfigCurrency(sel.ProviderKey, sel.Config)
 	}
 	if selectedCurrency != methodCurrency {
-		payAmountStr, payAmount, err = calculateCreateOrderPayAmount(limitAmount, feeRate, selectedCurrency)
+		payAmountStr, payAmount, err = calculateCreateOrderPayAmountForOrderType(limitAmount, feeRate, selectedCurrency, req.OrderType, cfg.BalanceRechargeMultiplier)
 		if err != nil {
 			return nil, err
 		}
@@ -630,6 +630,24 @@ func calculateCreateOrderPayAmount(limitAmount, feeRate float64, currency string
 	return payAmountStr, payAmount, nil
 }
 
+func calculateCreateOrderPayAmountForOrderType(limitAmount, feeRate float64, currency, orderType string, multiplier float64) (string, float64, error) {
+	paymentAmount := limitAmount
+	if orderType == payment.OrderTypeSubscription {
+		paymentAmount = calculateSubscriptionGatewayBaseAmount(limitAmount, multiplier, currency)
+	}
+	return calculateCreateOrderPayAmount(paymentAmount, feeRate, currency)
+}
+
+func calculateSubscriptionGatewayBaseAmount(amount, multiplier float64, currency string) float64 {
+	if currency != payment.DefaultPaymentCurrency {
+		return amount
+	}
+	return decimal.NewFromFloat(amount).
+		Div(decimal.NewFromFloat(normalizeBalanceRechargeMultiplier(multiplier))).
+		Round(int32(payment.CurrencyMaxFractionDigits(currency))).
+		InexactFloat64()
+}
+
 func validateCreateOrderAmountCurrency(amount float64, currency string) error {
 	amountStr := strconv.FormatFloat(amount, 'f', -1, 64)
 	if _, err := payment.AmountToMinorUnit(amountStr, currency); err != nil {

backend/internal/service/payment_order_result_test.go

@@ -161,27 +161,39 @@ func TestCalculateCreateOrderPayAmountUsesCurrencyPrecision(t *testing.T) {
 	}
 }
 
-func TestCalculateCreateOrderPayAmountForSubscriptionKeepsDirectPrice(t *testing.T) {
+func TestCalculateCreateOrderPayAmountForSubscriptionConvertsCNYPrice(t *testing.T) {
 	t.Parallel()
 
-	amountStr, amount, err := calculateCreateOrderPayAmount(5, 0, "CNY")
+	amountStr, amount, err := calculateCreateOrderPayAmountForOrderType(9.99, 0, "CNY", payment.OrderTypeSubscription, 0.14)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
-	if amountStr != "5.00" || amount != 5 {
-		t.Fatalf("subscription CNY pay amount = (%q, %v), want (5.00, 5)", amountStr, amount)
+	if amountStr != "71.36" || amount != 71.36 {
+		t.Fatalf("subscription CNY pay amount = (%q, %v), want (71.36, 71.36)", amountStr, amount)
 	}
 }
 
-func TestCalculateCreateOrderPayAmountForSubscriptionAppliesFeeToDirectPrice(t *testing.T) {
+func TestCalculateCreateOrderPayAmountForSubscriptionAppliesFeeAfterCNYConversion(t *testing.T) {
 	t.Parallel()
 
-	amountStr, amount, err := calculateCreateOrderPayAmount(5, 2.5, "CNY")
+	amountStr, amount, err := calculateCreateOrderPayAmountForOrderType(9.99, 2.5, "CNY", payment.OrderTypeSubscription, 0.14)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
-	if amountStr != "5.13" || amount != 5.13 {
-		t.Fatalf("subscription CNY pay amount with fee = (%q, %v), want (5.13, 5.13)", amountStr, amount)
+	if amountStr != "73.15" || amount != 73.15 {
+		t.Fatalf("subscription CNY pay amount with fee = (%q, %v), want (73.15, 73.15)", amountStr, amount)
+	}
+}
+
+func TestCalculateCreateOrderPayAmountForSubscriptionKeepsNonCNYPrice(t *testing.T) {
+	t.Parallel()
+
+	amountStr, amount, err := calculateCreateOrderPayAmountForOrderType(9.99, 0, "USD", payment.OrderTypeSubscription, 0.14)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if amountStr != "9.99" || amount != 9.99 {
+		t.Fatalf("subscription USD pay amount = (%q, %v), want (9.99, 9.99)", amountStr, amount)
 	}
 }