Halfcaf

Headless work mode for macOS. One menu bar click, and your Mac goes dark while your work keeps going. Reverses cleanly when you return.

halfcaf.app

---

Install

brew tap rasterandstate/tap
brew install --cask halfcaf

That installs the menu bar app into /Applications and the companion CLI onto your PATH.

CLI only:

brew install rasterandstate/tap/halfcaf

Or grab the latest signed and notarized DMG directly from downloads.halfcaf.app/halfcaf-1.0.0.dmg.

Requires macOS 14 (Sonoma) or later on Apple Silicon.

What it does

When you walk away from your Mac:

• Holds a system power assertion so background work keeps running.
• Dims every active display to 0 (the panel goes black; backlight off; auto-brightness can't fight you).
• Mutes audio.
• Optionally enables a Mac-only Focus mode so notifications don't light up the room.

When you come back, every captured value is restored. SIGKILL, crash, hard reboot, the auto-restore on next launch reverses the state. The CLI uses IOPMAssertion so the kernel handles the caffeination side under any termination.

Why

caffeinate, Amphetamine, and Raycast Coffee answer "how long should I prevent sleep?" None of them answer "the user is absent but the work is not."

The old workaround was hand-assembled state: caffeinate, plus manually dim brightness to zero, plus DND on, plus mute. Then remember to undo all of it.

Halfcaf collapses that into one declarative command (or one menu bar click) with a clean reverse on exit.

The name is a barista term, half-caffeinated: full system caffeination, but display, audio, and notification stimulation dialed back.

Use it

From the menu bar:

1. Click the moon icon
2. Click Engage
3. Walk away
4. When you return, hit ⌘⇧⎋ anywhere (works while the screen is dark) or click Disengage

From the terminal:

halfcaf                       # engage; Ctrl+C to disengage
halfcaf -t 4h                 # disengage automatically after 4 hours
halfcaf -- ./long-render.sh   # disengage when the command exits
halfcaf -w 12345              # disengage when pid 12345 exits
halfcaf --status              # show the active session

Privacy

Halfcaf does not phone home. It has no telemetry, no analytics, no crash reporter. It reads your display brightness, audio mute state, and the name of your current Focus mode at engage time, writes those values to ~/Library/Application Support/halfcaf/state.json, and uses them to restore at disengage time. That file never leaves your Mac.

The CLI uses Apple's private DisplayServices framework via dlopen to read and set brightness on Apple Silicon, since no public API exists. This is the same path used by BetterDisplay and MonitorControl.

License

MIT. Copyright © 2026 Stephen Way / Raster & State.