CREATE TABLE IF NOT EXISTS im_group_messages (
  id BIGINT NOT NULL AUTO_INCREMENT,
  topic VARCHAR(64) NOT NULL COMMENT '群 Topic，如 grp_xxx',
  group_id BIGINT NOT NULL COMMENT '业务群 ID，便于分区、治理和统计',
  seqid BIGINT NOT NULL COMMENT '群内消息序号，由 Redis 原子发号',
  from_user BIGINT NOT NULL COMMENT '发送人用户 ID',
  client_msg_id VARCHAR(64) NULL COMMENT '客户端幂等消息 ID',
  msg_type VARCHAR(32) NOT NULL DEFAULT 'text' COMMENT 'text/image/file/audio/video/system 等',
  status VARCHAR(32) NOT NULL DEFAULT 'normal' COMMENT 'normal/recalled/deleted/blocked',
  content JSON NULL COMMENT '消息正文或 Drafty 内容',
  head JSON NULL COMMENT '消息头，包含 @、引用、客户端能力等',
  mentioned_user_ids JSON NULL COMMENT '@ 用户列表，便于提醒和检索',
  mention_all TINYINT(1) NOT NULL DEFAULT 0 COMMENT '是否 @ 全体',
  reply_seqid BIGINT NULL COMMENT '回复的群消息 seq',
  root_seqid BIGINT NULL COMMENT '线程或合并上下文根消息 seq',
  file_count INT NOT NULL DEFAULT 0 COMMENT '附件数量',
  content_size INT NOT NULL DEFAULT 0 COMMENT '正文 JSON 序列化后的字节数',
  has_risk TINYINT(1) NOT NULL DEFAULT 0 COMMENT '是否命中风控或内容安全',
  audit_status VARCHAR(32) NOT NULL DEFAULT 'pass' COMMENT 'pass/pending/reject',
  version INT NOT NULL DEFAULT 1 COMMENT '编辑版本',
  recalled_at DATETIME(3) NULL,
  recalled_by BIGINT NULL,
  deleted_at DATETIME(3) NULL,
  expires_at DATETIME(3) NULL COMMENT '可选保留期，便于过期归档或清理',
  created_at DATETIME(3) NOT NULL,
  updated_at DATETIME(3) NOT NULL,
  PRIMARY KEY (id),
  UNIQUE KEY uk_im_group_messages_group_seq (group_id, seqid),
  UNIQUE KEY uk_im_group_messages_topic_seq (topic, seqid),
  UNIQUE KEY uk_im_group_messages_topic_sender_client_mid (topic, from_user, client_msg_id),
  KEY idx_im_group_messages_group_created (group_id, created_at),
  KEY idx_im_group_messages_group_status_seq (group_id, status, seqid),
  KEY idx_im_group_messages_topic_created (topic, created_at),
  KEY idx_im_group_messages_topic_from_seq (topic, from_user, seqid),
  KEY idx_im_group_messages_audit (audit_status, created_at),
  KEY idx_im_group_messages_expires (expires_at)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;