# Demo: phone-use diagnostic lab ## Mental model `Auto-Lock = Never` only keeps the screen from timing out. It does not remove unlock, trust, pairing, permission, or app-state requirements. ## Fault tree | Symptom | First check | Likely layer | Next question | |---|---|---|---| | Device not listed | `idevice_id -l` and `xcrun xctrace list devices` | Device discovery | Is USB connected and trusted? | | Device listed but action fails | Is the phone unlocked? | Unlock/security | Did security timeout require a fresh unlock? | | Device controllable but app state wrong | Screenshot/current app | App state | Is the target app foregrounded and logged in? | | Agent gives vague next step | Attach preflight output | Prompt quality | Which layer failed: discovery, trust, unlock, permission, or app state? | ## Question template ``` phone-use 卡住了。目标动作是：<action>。 preflight 输出： <paste output> 设备状态：<locked/unlocked/trusted/unknown> 请先判断卡在 discovery、trust、unlock、permission 还是 app state，再给下一步命令。 ```