接入分销订单支付退款与站点隔离

backend/internal/modules/chat/listing_group.go

@@ -91,7 +91,7 @@ func EnsureListingConversation(tx *gorm.DB, listing model.RentalListing, preferr
 	// 4. 取二维码(带行锁)
 	var qrcode *model.ChatQrCode
 	var qrcodeImageURL string
-	qrcodeObj, err := fetchUnusedQrCode(tx)
+	qrcodeObj, err := fetchUnusedQrCodeForListing(tx, listing.ID)
 	if err != nil {
 		return nil, err
 	}
@@ -301,12 +301,32 @@ func updateConversationLastMessage(tx *gorm.DB, conversationID uint64, message *
 }
 
 func fetchUnusedQrCode(tx *gorm.DB) (*model.ChatQrCode, error) {
+	return fetchUnusedQrCodeForSite(tx, nil)
+}
+
+func fetchUnusedQrCodeForListing(tx *gorm.DB, listingID uint64) (*model.ChatQrCode, error) {
+	var relation model.DistributionSiteAccount
+	if err := tx.Where("listing_id = ? AND display_status = 'enabled'", listingID).Order("id ASC").First(&relation).Error; err == nil {
+		return fetchUnusedQrCodeForSite(tx, &relation.SiteID)
+	} else if !errors.Is(err, gorm.ErrRecordNotFound) {
+		// 兼容尚未执行分销迁移的环境，继续使用全局二维码池。
+		return fetchUnusedQrCodeForSite(tx, nil)
+	}
+	return fetchUnusedQrCodeForSite(tx, nil)
+}
+
+func fetchUnusedQrCodeForSite(tx *gorm.DB, siteID *uint64) (*model.ChatQrCode, error) {
 	var qrcode model.ChatQrCode
 	now := time.Now()
-
-	err := tx.Where("status = ?", QrCodeStatusUnused).
+	query := tx.Where("status = ?", QrCodeStatusUnused).
 		Where("expires_at IS NULL OR expires_at > ?", now).
-		Order("id ASC").
+		Order("id ASC")
+	if siteID == nil {
+		query = query.Where("distribution_site_id IS NULL")
+	} else {
+		query = query.Where("distribution_site_id = ?", *siteID)
+	}
+	err := query.
 		Limit(1).
 		Clauses(clause.Locking{Strength: "UPDATE"}).
 		First(&qrcode).Error