-- 创建知识库对话会话表
CREATE TABLE IF NOT EXISTS chat_session (
    session_id BIGINT PRIMARY KEY AUTO_INCREMENT COMMENT '会话ID',
    project_id BIGINT NOT NULL COMMENT '项目ID',
    user_id BIGINT NOT NULL COMMENT '创建用户ID',
    model_config_id BIGINT NOT NULL COMMENT '使用的LLM模型配置ID',
    title VARCHAR(255) NOT NULL COMMENT '会话标题',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间',
    INDEX idx_project_user (project_id, user_id),
    INDEX idx_created_at (created_at)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci COMMENT='知识库对话会话表';

-- 创建知识库对话消息表
CREATE TABLE IF NOT EXISTS chat_message (
    message_id BIGINT PRIMARY KEY AUTO_INCREMENT COMMENT '消息ID',
    session_id BIGINT NOT NULL COMMENT '所属会话ID',
    role VARCHAR(20) NOT NULL COMMENT '角色(user/assistant)',
    content LONGTEXT NOT NULL COMMENT '消息内容',
    retrieved_docs JSON COMMENT '检索到的相关文档(JSON数组)',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
    FOREIGN KEY (session_id) REFERENCES chat_session(session_id) ON DELETE CASCADE,
    INDEX idx_session_id (session_id),
    INDEX idx_created_at (created_at)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci COMMENT='知识库对话消息表';