Keep AI agents running when you close a MacBook lid

The short answer

To keep Claude Code, Codex, OpenCode, Cursor, a build, or another local task running after you close a MacBook, the Mac must remain awake through the lid-close transition. Apple's supported closed-display setup uses an external monitor and usually power. Without that hardware, a lid-focused utility such as StillOn is the direct option on a supported Apple-silicon or Intel MacBook.

StillOn does not need an external monitor, dock, or HDMI dummy plug. Start the task, arm StillOn, and close the lid. The built-in display turns off, the macOS session locks, and the existing work can continue. StillOn keeps the computer available; supported local connections can report agent lifecycle state, but StillOn does not operate the agent or read its work.

Start with the exact problem

Closing a MacBook normally triggers system sleep. An AI coding agent, build, download, or local automation cannot make progress while the computer is asleep. Keeping the screen merely dim is not the same as keeping the system available after the lid sensor changes state.

StillOn is built for this narrow case on Apple-silicon and Intel Macs running macOS 13 or later. It suppresses the lid-close sleep transition only after you arm it, asks the display to turn off, and locks the session. It does not run the agent itself and it does not certify that the task is healthy.

Before the first lid-closed run

Test every dependency while the Mac is open. Start the agent, confirm it can progress without another prompt, and verify the separate connection you plan to use for checking it. That might be the agent product’s own remote session, Screen Sharing, or SSH. Configure and secure that tool according to its own documentation before relying on it.

Keep the Mac on a hard, ventilated surface. A closed display reduces one source of power use, but CPU, GPU, storage, and network activity can still produce heat. Do not test inside a sleeve, backpack, drawer, or other enclosed space.

• Use Apple silicon or Intel with macOS 13 or later.
• Connect power for a long run, or set a conservative battery stop.
• Verify the task and remote-check path while the lid is open.
• Place the Mac on a stable surface with unobstructed ventilation.
• Save work that cannot be reconstructed.

Arm StillOn deliberately

For a single close, hold Fn as you close the lid. For repeated closes during the same work period, use the persistent control in the StillOn menu-bar app. The explicit gesture is there so an ordinary close remains ordinary unless you choose otherwise.

Wait for the display to go dark and for the notebook to finish the physical transition. StillOn locks the session as part of this path. If you change your mind, reopen the lid; the app restores normal lid behaviour when the lid opens.

Verify from the outside

Use the independently configured connection to check that the Mac is reachable and that the agent’s own session shows new progress. Reachability proves only that a connection worked. Agent output, a completed build, or another task-specific signal is what proves the work progressed.

For the first several runs, keep the interval short and stay nearby. Reopen the lid if the connection drops, the task behaves unexpectedly, the Mac feels unusually hot, or battery state is uncertain. A monitoring plan should fail safe: lack of evidence is a reason to check locally, not a reason to assume success.

• Check that the Mac responds through the pre-tested connection.
• Check a task-specific progress signal, not only network reachability.
• Confirm the display is off and the session is locked when reopened.
• Confirm ordinary lid-sleep behaviour returns after disarming or quitting.

Know what StillOn does not do

StillOn can stop at the battery and temperature limits you configure, but those limits cannot make an enclosed running Mac safe. It does not restart failed agents, preserve an unsaved prompt, judge whether a task succeeded, or provide its own remote desktop.

The lid control uses an undocumented macOS power-management interface. Apple may change that interface in a future update, so test a short run after major macOS upgrades before trusting a long unattended session.

StillOn, caffeinate, or a general keep-awake app?

Use caffeinate when the lid stays open and you only need to prevent idle sleep for a command or a fixed period. General keep-awake apps can offer timers and process triggers, but confirm explicitly that they support a fully closed MacBook without an external display; ordinary power assertions do not necessarily override lid-close sleep.

Use StillOn when the requirement is narrow: a supported MacBook should keep running after its lid physically closes. StillOn can connect locally to Claude Code, Codex, OpenCode, and Cursor so it knows when supported agents start and finish; manual controls still cover every other app and task. It does not inspect prompts, code, tool arguments, file paths, or model output, and it does not claim that a task finished successfully.