Keep the Mac awake while your agents work

Part one: system sleep

caffeinate -i (or a power assertion like PreventUserIdleSystemSleep) keeps the machine from idle-sleeping. Every keep-awake utility does this.

Part two: display sleep

A separate assertion (PreventUserIdleDisplaySleep) keeps the screen on. Most tools do this too.

Part three: the one everyone forgets

The screen-saver / lock-screen idle timer is a third mechanism that power assertions do not touch. With “require password after screen saver” enabled, your Mac can lock over a perfectly awake session. The fix is periodically declaring user activity (IOPMAssertionDeclareUserActivity) — which resets the lock timer the way moving the mouse would.

What NapCat does

• Holds all three — system, display, and the activity heartbeat — during a fake nap, and automatically whenever a watched agent is working.
• Lets go the moment the last agent stops, so your normal lock behavior returns.
• Optional battery guard: release below 15% unplugged, so a forgotten overnight run can’t drain the Mac flat.