会话不断线Sessions never die
类 screen/tmux 的会话保持,但不需要学任何命令。设备端 agent 守护每个 PTY:用户端关掉、网络断开都不影响任务,重连自动恢复现场,最近输出随时回看。screen/tmux-style persistence, without learning any new commands. The device agent keeps every PTY alive — closing the client or dropping the network never touches the task. Reattach restores the screen; recent output stays reviewable.