-- 将历史平板会话归入手机设备桶，确保新旧数据使用同一套 PC/手机上限。
UPDATE worker_sessions
SET device_type = 'mobile', updated_at = NOW()
WHERE device_type = 'tablet';

UPDATE worker_sessions
SET device_type = 'pc', updated_at = NOW()
WHERE device_type IS NULL OR device_type NOT IN ('pc', 'mobile');
