fix(distribution): 修正分销模式判定与结算入账，冻结未确认分成

按买卖站点纯函数判定五种模式，分站卖主站货命中 two_party_platform_receive。
结算批次只收本站 site party，平台分成不再进入分销钱包；生产环境冻结结算入账与站点提现。

backend/internal/modules/distribution/lifecycle.go

@@ -24,74 +24,149 @@ func distributionTablesPresent(tx *gorm.DB) bool {
 	return distributionTablePresent
 }
 
-// ResolveOrderSourceTx 校验收号方站点与售出方站点、账号展示关系和生效规则，供正常订单创建事务写入快照引用。
-func ResolveOrderSourceTx(tx *gorm.DB, siteCode string, listingID, accountID uint64, at time.Time) (*model.DistributionSite, *model.DistributionRuleVersion, error) {
+// resolveDistributionMode 只根据买卖双方站点判定模式，不查库、不猜规则。
+// buySiteID / listingSiteID 为 0 表示主站。
+func resolveDistributionMode(buySiteID, listingSiteID uint64) string {
+	switch {
+	case buySiteID == 0 && listingSiteID == 0:
+		return ""
+	case buySiteID == 0:
+		return ModeTwoPartyDistributorReceive
+	case listingSiteID == 0:
+		return ModeTwoPartyPlatformReceive
+	case buySiteID == listingSiteID:
+		return ModeSiteSelfSell
+	default:
+		return ModeThreeParty
+	}
+}
+
+func derefSiteID(id *uint64) uint64 {
+	if id == nil || *id == 0 {
+		return 0
+	}
+	return *id
+}
+
+func loadListingSiteID(tx *gorm.DB, listingID uint64) (uint64, error) {
+	if listingID == 0 {
+		return 0, nil
+	}
 	var listing model.RentalListing
-	var listingSiteID *uint64
-	if listingID > 0 {
-		if err := tx.Select("id, distribution_site_id").First(&listing, listingID).Error; err == nil {
-			listingSiteID = listing.DistributionSiteID
+	if err := tx.Select("id, distribution_site_id").First(&listing, listingID).Error; err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return 0, nil
 		}
+		return 0, err
+	}
+	return derefSiteID(listing.DistributionSiteID), nil
+}
+
+func loadActiveSiteByID(tx *gorm.DB, siteID uint64) (*model.DistributionSite, error) {
+	var site model.DistributionSite
+	if err := tx.Where("id = ? AND status = 'active'", siteID).First(&site).Error; err != nil {
+		return nil, ErrSiteNotFound
+	}
+	return &site, nil
+}
+
+func loadActiveSellSiteByCode(tx *gorm.DB, siteCode string) (*model.DistributionSite, error) {
+	var site model.DistributionSite
+	if err := tx.Where("site_code = ? AND status = 'active' AND display_account_enabled = ?", siteCode, true).First(&site).Error; err != nil {
+		return nil, ErrSiteNotFound
+	}
+	return &site, nil
+}
+
+func ensureAccountDisplayTx(tx *gorm.DB, siteID, listingID, accountID uint64) error {
+	var relation model.DistributionSiteAccount
+	if err := tx.Where("site_id = ? AND listing_id = ? AND account_id = ? AND display_status = 'enabled'", siteID, listingID, accountID).First(&relation).Error; err != nil {
+		return ErrAccountDisplayNotFound
+	}
+	return nil
+}
+
+func findActiveRuleTx(tx *gorm.DB, siteID uint64, mode string, at time.Time) (*model.DistributionRuleVersion, error) {
+	var rule model.DistributionRuleVersion
+	err := tx.Where("mode = ? AND status = 'active' AND effective_from <= ? AND (effective_to IS NULL OR effective_to > ?)", mode, at, at).
+		Where("site_id = ? OR site_id IS NULL", siteID).
+		Order("CASE WHEN site_id IS NULL THEN 1 ELSE 0 END, effective_from DESC, id DESC").
+		First(&rule).Error
+	if err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return nil, ErrRuleNotFound
+		}
+		return nil, err
+	}
+	return &rule, nil
+}
+
+// ResolveOrderSourceTx 先按买卖站点判定模式，再查该 mode 的生效规则，不再在两方规则之间猜优先级。
+func ResolveOrderSourceTx(tx *gorm.DB, siteCode string, listingID, accountID uint64, at time.Time) (*model.DistributionSite, *model.DistributionRuleVersion, error) {
+	listingSiteID, err := loadListingSiteID(tx, listingID)
+	if err != nil {
+		return nil, nil, err
 	}
 
-	// 1. 两方均无分销站：纯主站交易
-	if siteCode == "" && listingSiteID == nil {
+	var buySite *model.DistributionSite
+	buySiteID := uint64(0)
+	if siteCode != "" {
+		buySite, err = loadActiveSellSiteByCode(tx, siteCode)
+		if err != nil {
+			return nil, nil, err
+		}
+		if err := ensureAccountDisplayTx(tx, buySite.ID, listingID, accountID); err != nil {
+			return nil, nil, err
+		}
+		buySiteID = buySite.ID
+	}
+
+	mode := resolveDistributionMode(buySiteID, listingSiteID)
+	if mode == "" {
 		return nil, nil, nil
 	}
 
-	// 2. 模式一：分销网收号、主站卖出 (ModeTwoPartyDistributorReceive)
-	if siteCode == "" && listingSiteID != nil {
-		var site model.DistributionSite
-		if err := tx.Where("id = ? AND status = 'active'", *listingSiteID).First(&site).Error; err != nil {
+	var anchor *model.DistributionSite
+	switch mode {
+	case ModeTwoPartyDistributorReceive:
+		anchor, err = loadActiveSiteByID(tx, listingSiteID)
+		if err != nil {
+			return nil, nil, err
+		}
+	default:
+		if buySite == nil {
 			return nil, nil, ErrSiteNotFound
 		}
-		var rule model.DistributionRuleVersion
-		query := tx.Where("mode = ? AND status = 'active' AND effective_from <= ? AND (effective_to IS NULL OR effective_to > ?)", ModeTwoPartyDistributorReceive, at, at).
-			Where("site_id = ? OR site_id IS NULL", site.ID).
-			Order("CASE WHEN site_id IS NULL THEN 1 ELSE 0 END, effective_from DESC, id DESC")
-		if err := query.First(&rule).Error; err != nil {
-			return nil, nil, ErrRuleNotFound
-		}
-		return &site, &rule, nil
+		anchor = buySite
 	}
 
-	// 3. 买家在分销站下单：校验售出站点状态与账号展示关系
-	var sellSite model.DistributionSite
-	if err := tx.Where("site_code = ? AND status = 'active' AND display_account_enabled = ?", siteCode, true).First(&sellSite).Error; err != nil {
-		return nil, nil, ErrSiteNotFound
-	}
-	var relation model.DistributionSiteAccount
-	if err := tx.Where("site_id = ? AND listing_id = ? AND account_id = ? AND display_status = 'enabled'", sellSite.ID, listingID, accountID).First(&relation).Error; err != nil {
-		return nil, nil, ErrAccountDisplayNotFound
+	rule, err := findActiveRuleTx(tx, anchor.ID, mode, at)
+	if err != nil {
+		return nil, nil, err
 	}
+	return anchor, rule, nil
+}
 
-	// 4. 解析生效规则：优先匹配有效规则版本
-	targetMode := ModeTwoPartyDistributorReceive
-	if listingSiteID != nil && *listingSiteID != sellSite.ID {
-		targetMode = ModeThreeParty
+func ruleFromVersion(rule model.DistributionRuleVersion) Rule {
+	return Rule{
+		Mode:                    rule.Mode,
+		PlatformReceiveRatio:    rule.PlatformReceiveRatio,
+		PlatformSellRatio:       rule.PlatformSellRatio,
+		DistributorReceiveRatio: rule.DistributorReceiveRatio,
+		DistributorSellRatio:    rule.DistributorSellRatio,
+		DistributorARatio:       rule.DistributorARatio,
+		DistributorBRatio:       rule.DistributorBRatio,
+		ServiceFeeValue:         rule.ServiceFeeValue,
+		ServiceFeeUnit:          rule.ServiceFeeUnit,
+		PaymentFeeBPS:           rule.PaymentFeeBPS,
+		TaxEnabled:              rule.TaxEnabled,
+		TaxRateBPS:              rule.TaxRateBPS,
 	}
-	var rule model.DistributionRuleVersion
-	query := tx.Where("status = 'active' AND effective_from <= ? AND (effective_to IS NULL OR effective_to > ?)", at, at).
-		Where("site_id = ? OR site_id IS NULL", sellSite.ID)
-	if targetMode == ModeThreeParty {
-		query = query.Where("mode = ?", ModeThreeParty)
-	} else {
-		query = query.Where("mode IN (?, ?)", ModeTwoPartyDistributorReceive, ModeTwoPartyPlatformReceive).
-			Order("CASE WHEN mode = '" + ModeTwoPartyDistributorReceive + "' THEN 0 ELSE 1 END")
-	}
-	query = query.Order("CASE WHEN site_id IS NULL THEN 1 ELSE 0 END, effective_from DESC, id DESC")
-	if err := query.First(&rule).Error; err != nil {
-		return nil, nil, ErrRuleNotFound
-	}
-	return &sellSite, &rule, nil
 }
 
 // calculateForRule 按规则快照计算手续费、服务费和分成基数。
 func calculateForRule(rule model.DistributionRuleVersion, input SettlementInput) (SettlementResult, error) {
-	return CalculateSettlement(Rule{
-		Mode: rule.Mode, ServiceFeeValue: rule.ServiceFeeValue, ServiceFeeUnit: rule.ServiceFeeUnit,
-		PaymentFeeBPS: rule.PaymentFeeBPS, TaxEnabled: rule.TaxEnabled, TaxRateBPS: rule.TaxRateBPS,
-	}, input)
+	return CalculateSettlement(ruleFromVersion(rule), input)
 }
 
 // SnapshotPaidOrderTx 在支付确认事务内幂等写入财务和参与方快照。
@@ -116,7 +191,7 @@ func SnapshotPaidOrderTx(tx *gorm.DB, orderID uint64, grossPaidCent int64) error
 	if err != nil {
 		return err
 	}
-	splits := SplitSettlement(Rule{Mode: rule.Mode}, result.SplitBaseAmountCent, markup)
+	splits := SplitSettlement(ruleFromVersion(rule), result.SplitBaseAmountCent, markup)
 	financial := model.DistributionOrderFinancial{OrderID: order.ID, SiteID: *order.DistributionSiteID, RuleVersionID: rule.ID, GrossPaidAmountCent: grossPaidCent, NetPaidAmountCent: result.NetPaidAmountCent, PaymentFeeBPS: rule.PaymentFeeBPS, PaymentFeeCent: result.PaymentFeeCent, ServiceFeeValue: rule.ServiceFeeValue, ServiceFeeUnit: rule.ServiceFeeUnit, ServiceFeeCent: result.ServiceFeeCent, MarkupAmountCent: markup, TaxEnabled: rule.TaxEnabled, TaxRateBPS: rule.TaxRateBPS, TaxAmountCent: result.TaxAmountCent, SplitBaseAmountCent: result.SplitBaseAmountCent, RoundingAdjustmentCent: SplitRemainderCent(result.SplitBaseAmountCent, splits), SettlementStatus: "pending"}
 	if err := tx.Where("order_id = ?", order.ID).Assign(financial).FirstOrCreate(&financial).Error; err != nil {
 		return err
@@ -130,12 +205,12 @@ func SnapshotPaidOrderTx(tx *gorm.DB, orderID uint64, grossPaidCent int64) error
 	}
 	parties := make([]model.DistributionOrderParty, 0, len(splits))
 	for _, split := range splits {
-		partyType := "site"
+		partyType := PartyTypeSite
 		if split.PartyRole == "platform_sell" || split.PartyRole == "platform_receive" {
-			partyType = "platform"
+			partyType = PartyTypePlatform
 		}
 		partyID := *order.DistributionSiteID
-		if partyType == "platform" {
+		if partyType == PartyTypePlatform {
 			partyID = 0
 		} else if split.PartyRole == "distributor_a" {
 			// 三方模式下 distributor_a 为商品收号站
@@ -175,7 +250,7 @@ func ApplyRefundTx(tx *gorm.DB, orderID uint64, refundAmountCent int64) error {
 	if err != nil {
 		return err
 	}
-	splits := SplitSettlement(Rule{Mode: rule.Mode}, result.SplitBaseAmountCent, financial.MarkupAmountCent)
+	splits := SplitSettlement(ruleFromVersion(rule), result.SplitBaseAmountCent, financial.MarkupAmountCent)
 	if err := tx.Model(&financial).Updates(map[string]any{"refund_amount_cent": refundAmountCent, "net_paid_amount_cent": result.NetPaidAmountCent, "payment_fee_cent": result.PaymentFeeCent, "service_fee_cent": result.ServiceFeeCent, "split_base_amount_cent": result.SplitBaseAmountCent, "rounding_adjustment_cent": SplitRemainderCent(result.SplitBaseAmountCent, splits), "settlement_status": "pending"}).Error; err != nil {
 		return err
 	}