支持客服入口按业务场景分流到客服分组

联系客服支持 scene（general/mohong），按用户与场景复用会话；摸大红入口走摸大红分组选人。

backend/internal/modules/chat/conversation.go

@@ -58,6 +58,7 @@ func (r *Repository) FindConversation(ctx context.Context, principal Principal,
 			OrderID:            conversation.OrderID,
 			ListingID:          conversation.ListingID,
 			Type:               conversation.Type,
+			SupportScene:       conversation.SupportScene,
 			Title:              conversation.Title,
 			Status:             conversation.Status,
 			Role:               "admin", // 管理员角色
@@ -131,20 +132,43 @@ func (r *Repository) FindOrderConversation(ctx context.Context, userID uint64, o
 	dto := row.toDTO(participants)
 	return &dto, nil
 }
-func (r *Repository) EnsureSupportConversation(ctx context.Context, userID uint64) (*ConversationDTO, error) {
+func (r *Repository) EnsureSupportConversation(ctx context.Context, userID uint64, scene string) (*ConversationDTO, error) {
+	scene, title, groupCode, welcome := resolveSupportScene(scene)
 	var conversationID uint64
 	err := r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
 		var existing model.ChatConversation
 		err := tx.Table("chat_conversations AS c").
 			Select("c.*").
 			Joins("JOIN chat_participants AS cp ON cp.conversation_id = c.id").
-			Where("c.type = ? AND cp.participant_type = ? AND cp.participant_id = ?", "general_support", "user", userID).
+			Where(
+				"c.type = ? AND c.support_scene = ? AND cp.participant_type = ? AND cp.participant_id = ?",
+				ConversationTypeGeneralSupport, scene, "user", userID,
+			).
 			Order("c.id ASC").
 			Limit(1).
 			Find(&existing).Error
 		if err != nil {
 			return err
 		}
+		// 兼容旧数据：scene=general 时也匹配未回填 support_scene 的历史会话
+		if existing.ID == 0 && scene == SupportSceneGeneral {
+			err = tx.Table("chat_conversations AS c").
+				Select("c.*").
+				Joins("JOIN chat_participants AS cp ON cp.conversation_id = c.id").
+				Where(
+					"c.type = ? AND (c.support_scene = '' OR c.support_scene IS NULL) AND cp.participant_type = ? AND cp.participant_id = ?",
+					ConversationTypeGeneralSupport, "user", userID,
+				).
+				Order("c.id ASC").
+				Limit(1).
+				Find(&existing).Error
+			if err != nil {
+				return err
+			}
+			if existing.ID > 0 && existing.SupportScene == "" {
+				_ = tx.Model(&existing).Update("support_scene", SupportSceneGeneral).Error
+			}
+		}
 		if existing.ID > 0 {
 			conversationID = existing.ID
 			return nil
@@ -152,9 +176,10 @@ func (r *Repository) EnsureSupportConversation(ctx context.Context, userID uint6
 
 		now := time.Now()
 		conversation := model.ChatConversation{
-			Type:   "general_support",
-			Title:  "平台客服",
-			Status: "active",
+			Type:         ConversationTypeGeneralSupport,
+			SupportScene: scene,
+			Title:        title,
+			Status:       "active",
 		}
 		if err := tx.Create(&conversation).Error; err != nil {
 			return err
@@ -169,7 +194,7 @@ func (r *Repository) EnsureSupportConversation(ctx context.Context, userID uint6
 				JoinedAt:        now,
 			},
 		}
-		if supportID := defaultSupportAdminID(tx); supportID > 0 {
+		if supportID := pickSupportAdminForScene(tx, groupCode); supportID > 0 {
 			participants = append(participants, model.ChatParticipant{
 				ConversationID:  conversation.ID,
 				ParticipantType: "admin",
@@ -189,7 +214,7 @@ func (r *Repository) EnsureSupportConversation(ctx context.Context, userID uint6
 			SenderType:     "system",
 			SenderRole:     "system",
 			ContentType:    "system",
-			Content:        "您好，客服会尽快回复，请直接描述您遇到的问题。",
+			Content:        welcome,
 			AttachmentURLS: emptyJSONList(),
 		}
 		if err := tx.Create(&message).Error; err != nil {