业务逻辑层:处理客服对话管理、用户认证、多语言切换等业务逻辑 3.数据访问层:封装数据库操作,提供统一的数据访问接口 4.AI服务层:集成智能问答引擎,处理自然语言理解与生成 mermaid graph...错误:'.... 'greeting'=>['你好','您好','嗨','哈喽'], 'farewell'=>['再见','拜拜','退出','结束对话'], 'help'=>['帮助','怎么用'...user_id`), KEY`sender_type_index`(`sender_type`), KEY`created_at_index`(`created_at`), CONSTRAINT`messages_conversations_foreign...`FOREIGN KEY(`conversation_id`)REFERENCES`conversations`(`id`), CONSTRAINT`messages_users_foreign`FOREIGN