# Insomniac: keep the Mac awake, lid closed, without cooking it

> A macOS menu-bar app that keeps a Mac awake with the lid shut, built as a safe wrapper around a privileged system command, with a live thermal cutoff so it never overheats.

Canonical URL: https://saifsiddiqui.in/work/insomniac/ (this is its markdown representation; the same URL serves HTML to browsers)
Other languages: hi: https://saifsiddiqui.in/hi/work/insomniac/ · kn: https://saifsiddiqui.in/kn/work/insomniac/ · ur: https://saifsiddiqui.in/ur/work/insomniac/ · te: https://saifsiddiqui.in/te/work/insomniac/ · ar: https://saifsiddiqui.in/ar/work/insomniac/ · hi-Latn: https://saifsiddiqui.in/hi-latn/work/insomniac/

**Role:** Built 0→1  
**Stack:** Swift, SwiftUI, macOS, IOKit

**Links**

- Web: https://saif-09.github.io/insomniac/

## Problem

I wanted my Mac to keep running with the lid shut. Not dimmed: actually working,
an AI agent overnight, an Xcode archive, a long sync, lid closed, no external
monitor. macOS calls that clamshell sleep, and it does not care that your task is
mid-flight.

The catch is in the mechanism. The popular keep-awake tools use IOKit power
assertions, and those do not prevent clamshell sleep unless you have an external
display, power, and a keyboard attached, exactly the setup I was trying to avoid.
The only lever that works with nothing attached is a privileged command: pmset
disablesleep. So the whole product is really one thing, a safe wrapper around a
dangerous system setting, and everything else exists to make that one lever safe
and pleasant to pull.

## Decisions

**Safety is the feature, not staying awake.** A generic paid keep-awake app is dead
on arrival: Amphetamine and caffeinate already do it for free. The unserved angle
was heat. A closed lid chokes airflow, and no existing tool says a word about it.
So Insomniac is not "stay awake", it is "stay awake without cooking the machine".

**Measure what macOS exposes honestly, not fake degrees.** The tempting version
reads a CPU temperature and shows a countdown in degrees. But Apple Silicon exposes
no supported way to read die temperature; anything claiming to is reading private
keys that break across models. So I built on ProcessInfo.thermalState (nominal,
fair, serious, critical), which needs no admin and is supported forever. And the
real protection is not an up-front prediction at all: it is a live thermal cutoff
that watches the state while the lid is closed and auto-stops the session if it
escalates. A prediction can be wrong; a live cutoff is ground truth.

**An architecture where the dangerous part is swappable.** Running pmset as root
has two paths: an AppleScript prompt that asks for a password on every toggle
(trivial, works day one) and a privileged helper over XPC that toggles silently
(production-grade, needs signing and a pinned contract). Instead of coupling the
app to either, I hid both behind one PowerControlling protocol. I shipped the
password-prompt version on day one and added the silent helper later with zero
caller changes. The helper is locked down: as a root daemon it only accepts XPC
connections pinned to this app's identifier and Team ID.

**The safety invariants are enforced by the code.** A keep-awake app has one
catastrophic failure: leaving sleep disabled after you are done. I treated "never
leave sleep disabled" as an invariant and closed every exit. Toggle off, auto-off,
thermal cutoff, and battery cutoff all restore sleep. Quit and logout defer
termination until the restore completes; the app refuses to die with sleep still
disabled. A hard crash cannot be intercepted, so on next launch the app detects
sleep disabled with no active session and offers to reset it. There is also no
"indefinite": the longest session is a hard 8-hour cap, because "forever" is
exactly the setting that leaves a dead, hot laptop in a bag.

**Honest UI, honest privacy.** The app is menu-bar only. The advisory shows a risk
level (low, moderate, high) and a plain message, never degrees I cannot read
honestly, and the weather nudge is deliberately the weakest input: a hot room can
raise risk, but a cold room can never make a cooking CPU safe. The weather location
comes from IP geolocation, city-level, so there is no GPS permission prompt; turn
weather off and the app sends nothing. No telemetry, no analytics.

**The bug I only found by living with it.** V1 kept the Mac awake, but the screen
stayed lit with the lid closed, because disabling sleep also stops macOS from
turning the internal display off. A backlight burning against the keyboard is
wasted battery and heat, the exact thing the app protects against. I added a lid
monitor that fires on the open-to-closed edge and puts the display to sleep with a
harmless user-level command, kept deliberately separate from the privileged helper.
Least privilege for the thing that does not need it.

**Ship now, own the rough edge.** The core feature needs the App Sandbox off, which
rules out the Mac App Store, so I shipped a direct download. Rather than spend days
on Apple's paperwork first, I shipped an un-notarized build now and made the
resulting Gatekeeper warning a guided, one-minute step: the installer is a
hand-drawn setup guide, the quarantine-clearing command sits right next to the app
as a copyable file, and the app strips its own quarantine flag on every launch so
the warning never comes back. The packaging script re-signs and notarizes with one
command the moment a certificate exists.

## Outcome

{/* TODO(saif): downloads / usage once it is public. Qualitative for now. */}

Insomniac is [live](https://saif-09.github.io/insomniac/): a menu-bar app that
keeps a Mac awake lid-closed, with a live thermal cutoff, a battery cutoff, crash
recovery, and silent toggling through a signed helper. The whole thing rests on two
rules: be honest (the real mechanism, risk levels instead of fake degrees, a weak
signal kept weak) and ship fast with the rough edges owned rather than hidden. A
keep-awake app is a small thing, but it touches a setting that can damage hardware,
so every shortcut that would have made the demo flashier would have made the
product less trustworthy.

All work: [/work/](/work/)

---

Mohd Saif, Product Engineer. I build solutions, not dead software.
Email: saifmd238@gmail.com · GitHub: https://github.com/Saif-09 · LinkedIn: https://www.linkedin.com/in/mohd-saif-134076141/ · Résumé (PDF): https://saifsiddiqui.in/resume

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