fix: support legacy payment method aliases

backend/internal/payment/load_balancer.go

@@ -231,6 +231,11 @@ func getInstanceChannelLimits(inst *dbent.PaymentProviderInstance, paymentType P
 	if cl, ok := limits[lookupKey]; ok {
 		return cl
 	}
+	if aliasKey := legacyVisibleMethodAlias(lookupKey); aliasKey != "" {
+		if cl, ok := limits[aliasKey]; ok {
+			return cl
+		}
+	}
 	return ChannelLimits{}
 }
 
@@ -321,14 +326,38 @@ func InstanceSupportsType(supportedTypes string, target PaymentType) bool {
 	if supportedTypes == "" {
 		return true
 	}
+	normalizedTarget := normalizeVisibleMethodSupportType(target)
 	for _, t := range strings.Split(supportedTypes, ",") {
-		if strings.TrimSpace(t) == target {
+		supported := strings.TrimSpace(t)
+		if supported == target || normalizeVisibleMethodSupportType(supported) == normalizedTarget {
 			return true
 		}
 	}
 	return false
 }
 
+func normalizeVisibleMethodSupportType(paymentType PaymentType) PaymentType {
+	switch strings.TrimSpace(paymentType) {
+	case TypeAlipay, TypeAlipayDirect:
+		return TypeAlipay
+	case TypeWxpay, TypeWxpayDirect:
+		return TypeWxpay
+	default:
+		return strings.TrimSpace(paymentType)
+	}
+}
+
+func legacyVisibleMethodAlias(paymentType PaymentType) PaymentType {
+	switch normalizeVisibleMethodSupportType(paymentType) {
+	case TypeAlipay:
+		return TypeAlipayDirect
+	case TypeWxpay:
+		return TypeWxpayDirect
+	default:
+		return ""
+	}
+}
+
 // GetInstanceConfig decrypts and returns the configuration for a provider instance by ID.
 func (lb *DefaultLoadBalancer) GetInstanceConfig(ctx context.Context, instanceID int64) (map[string]string, error) {
 	inst, err := lb.db.PaymentProviderInstance.Get(ctx, instanceID)

backend/internal/payment/load_balancer_test.go

@@ -68,10 +68,16 @@ func TestInstanceSupportsType(t *testing.T) {
 			expected:       true,
 		},
 		{
-			name:           "partial match should not succeed",
+			name:           "legacy alipay direct supports canonical visible method",
 			supportedTypes: "alipay_direct",
 			target:         "alipay",
-			expected:       false,
+			expected:       true,
+		},
+		{
+			name:           "legacy wxpay direct supports canonical visible method",
+			supportedTypes: "wxpay_direct",
+			target:         "wxpay",
+			expected:       true,
 		},
 		{
 			name:           "empty supported types means all supported",
@@ -92,6 +98,22 @@ func TestInstanceSupportsType(t *testing.T) {
 	}
 }
 
+func TestGetInstanceChannelLimitsFallsBackToLegacyDirectAliases(t *testing.T) {
+	t.Parallel()
+
+	inst := testInstance(1, TypeAlipay, makeLimitsJSON(TypeAlipayDirect, ChannelLimits{SingleMax: 66}))
+	got := getInstanceChannelLimits(inst, TypeAlipay)
+	if got.SingleMax != 66 {
+		t.Fatalf("getInstanceChannelLimits() = %+v, want SingleMax=66", got)
+	}
+
+	wxInst := testInstance(2, TypeWxpay, makeLimitsJSON(TypeWxpayDirect, ChannelLimits{SingleMin: 8}))
+	wxGot := getInstanceChannelLimits(wxInst, TypeWxpay)
+	if wxGot.SingleMin != 8 {
+		t.Fatalf("getInstanceChannelLimits() = %+v, want SingleMin=8", wxGot)
+	}
+}
+
 // ---------------------------------------------------------------------------
 // Helper to build test PaymentProviderInstance values
 // ---------------------------------------------------------------------------