Your agent didn't fail. You closed the lid

SleepSwitch is a macOS menu bar toggle that stops your Mac from sleeping — lid closed included. One click, no password prompts, and a battery guard so you don't cook your laptop in a bag.

You kick off a long agent run — Claude Code refactoring half a service, Codex grinding through a test suite, some pipeline that's going to take 40 minutes. You close the lid and walk away.

You come back to a session that died somewhere in the middle. Half the edits applied. The agent's context gone. Whatever it was in the middle of writing, gone with it.

Your Mac went to sleep. That's it. That's the whole bug.

Why caffeinate doesn't save you

The standard answer is caffeinate -dimsu. It works — right up until you close the lid, at which point the Mac sleeps anyway.

Lid-close sleep is a separate setting, it lives behind sudo, and no user-level assertion touches it:

sudo pmset -a disablesleep 1   # the one that actually matters

So the real workflow becomes: remember the flag, type your password, remember to turn it back off later, and — the fun part — forget once, drop the laptop in a bag, and it runs hot in there until the battery is flat.

I got tired of that loop and wrote SleepSwitch. One menu bar icon, one click, both layers at once.

The icon is the state

Left click toggles. Right click is the menu — launch behaviour, login item, updates, the sudo rule.

Close the lid with the mode on and you get a muted porcelain tone; open it and a higher one. Enough to confirm the machine stayed awake without opening anything to check.

Why this matters for agentic workflows specifically

This started as a "keep the build running" utility. Then AI coding agents happened, and it turned out they're the worst possible workload for macOS power management:

• They run long. A serious agent session is tens of minutes of tool calls, not a 30-second command.
• They look idle to the OS. The heavy lifting is on a remote API. Your Mac is waiting on network I/O with no keyboard, no mouse, no display activity. macOS sees a machine nobody is using.
• They fail badly, not gracefully. A dropped SSH session you just reconnect. An agent halfway through a multi-file edit leaves you diffing to figure out what actually landed.
• The natural instinct is to close the lid. You started the run precisely so you could go do something else.

So: hit the switch, close the lid, come back to a finished run. Same for npm run build on a monorepo, a long download, a render, an SSH session you need to survive lunch.

Two layers, because macOS treats these as two different things

The IOKit assertions are held by the process, so they evaporate the moment the app dies — they can't get stuck. The pmset setting is different: it's a system setting that outlives the process. So the app clears it on quit, on SIGTERM, and reports the real state at launch by reading SleepDisabled straight from IOPMrootDomain rather than trusting its own memory of what it did.

The password question

pmset disablesleep needs root, and prompting on every toggle makes the whole thing pointless. So the installer writes /etc/sudoers.d/sleepswitch:

you ALL=(root) NOPASSWD: /usr/bin/pmset -a disablesleep 0
you ALL=(root) NOPASSWD: /usr/bin/pmset -a disablesleep 1

Two commands, no wildcards. sudo matches arguments exactly, so this grants "toggle one sleep setting" and nothing else — pmset -a sleep 0 still asks for a password.

The rule is written, validated with visudo and installed entirely as root inside a mode-0700 temp directory, so there's no user-writable file to swap in between the check and the install. The username is validated before it reaches sudoers, and only an account in the admin group gets it.

Don't want it? Untick the box at install time, remove it later from the menu, or:

sudo rm /etc/sudoers.d/sleepswitch

The battery guard

The failure mode I mentioned above is real and it's the reason this feature exists: mode on, lid closed, laptop in a bag, cooking.

So the mode switches itself off once the battery drops to a threshold you pick — 20% out of the box — and, optionally, the instant the power adapter is unplugged. A notification tells you which of the two fired.

Two small decisions I'd defend:

• On a Mac with no built-in battery those settings aren't shown at all. An inert control is worse than no control. The check is by power-source type, since a UPS on a desktop counts as one too.
• If the battery reading is missing, nothing trips. Switching the mode off for a reason the app can't state to you is worse than leaving it alone.

Install

Grab the .pkg from the latest release and open it.

It's not signed with an Apple Developer certificate, so macOS blocks the first open. On Sequoia and newer, Control-click no longer overrides that: open the .pkg, let it be refused, then System Settings → Privacy & Security → Open Anyway. One time.

Or from source:

./make-installer.sh     # → dist/SleepSwitch-<version>.pkg
./install.sh            # or straight into /Applications

Command Line Tools is the only requirement. The icon is drawn in code at build time, the lid tones are synthesised at build time — no binary assets in the repo. A missing translation fails the build.

One warning worth repeating: turn the mode off before deleting the app. The pmset setting is a system setting; dragging the app to the Trash while the mode is on leaves you with a Mac that won't sleep and no switch left to turn it off. The Uninstall SleepSwitch… menu item handles the ordering for you.

The rest of it

• Updates: asks GitHub once a day, offers a notification, never swaps binaries behind your back — it downloads the .pkg and hands it to the system Installer. Requests pinned to https on GitHub hosts, redirects included. Turn the check off and nothing goes over the network.
• Screen lock is a separate macOS setting and SleepSwitch doesn't touch it. If your Mac asks for a password on lid-open, that's the lock, and macOS deliberately requires your account password to change it.
• macOS 13+, universal binary, English and Russian, plain Swift, no dependencies, no daemon, no telemetry. MIT.

github.com/AppsGanin/SleepSwitch — stars are appreciated, issues more so. ☕️