Wakeful/README.md

Wakeful

A menu bar switch for macOS sleep. Does what caffeinate -dis does, without a terminal window pinned open for the rest of the day.

Lives in the menu bar, toggles with a global shortcut, starts at login, and can turn itself on when you plug in or connect an external display.

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Why this exists

caffeinate is the right tool with the wrong interface. It's a foreground process, so it needs a terminal window that you can't close, that survives nothing, and that tells you nothing about its own state. Wakeful holds exactly the same kernel assertions — it just does it from a background app with a switch.

Verify that for yourself at any time:

pmset -g assertions

You'll see PreventUserIdleDisplaySleep, PreventUserIdleSystemSleep, and PreventSystemSleep attributed to Wakeful, with the reason string "Wakeful is keeping this Mac awake".

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Design

Approach

Rather than shelling out to /usr/bin/caffeinate and babysitting a child process, Wakeful calls IOPMAssertionCreateWithName directly — which is all caffeinate itself does. This means:

• No subprocess, no orphaned caffeinate in Activity Monitor if the app dies.
• The kernel releases every assertion automatically on process exit, so a crash can never leave your Mac permanently awake.
• Assertions are named and attributed properly in pmset -g assertions.

Assertion → caffeinate mapping

Menu item	IOKit assertion	caffeinate
Display sleep	PreventUserIdleDisplaySleep	-d
System idle sleep	PreventUserIdleSystemSleep	-i
Full system sleep (AC only)	PreventSystemSleep	-s
Disk spin-down	PreventDiskIdle	-m

Default is -d -i -s, i.e. caffeinate -dis. The Prevent submenu shows the equivalent command for whatever you've selected.

Module layout

Sources/Wakeful/
  main.swift            NSApplication bootstrap, .accessory activation policy
  AppDelegate.swift     NSStatusItem + the whole menu, rebuilt on every open
  WakeController.swift  State machine: on/off, source, expiry, smart rules
  SleepBlocker.swift    Owns live IOPMAssertionIDs; declarative apply(Set)
  PowerMonitor.swift    IOPS notifications (AC / charge) + screen-change notifications
  Preferences.swift     UserDefaults, all keys settable via `defaults write`
  HotKey.swift          Carbon RegisterEventHotKey global shortcut
  LaunchAtLogin.swift   SMAppService.mainApp registration

Two design decisions worth calling out:

The menu is rebuilt from scratch in menuNeedsUpdate(_:). Menu bar apps accumulate bugs from trying to keep dozens of checkmarks in sync with model state. Throwing the menu away and regenerating it from Preferences and WakeController on each open prevents desync between openings, and a menu opens rarely enough that the cost is irrelevant. State can still change while the menu is open (a timed session expires, you plug in), so the few items whose meaning depends on it — the status line, the Turn On / Turn Off toggle and "Add 30 minutes" — are refreshed live, and the toggle carries the action it displays. A click never does the opposite of its label: if the toggle changed meaning just as you clicked, the click is ignored.

SleepBlocker.apply(_:) is declarative, not imperative. You hand it the set of assertions you want held and it reconciles the delta. No if held { release } branching at call sites, and repeated calls are free.

Smart activation semantics

The tricky part of conditional activation is not the conditions, it's not fighting the user. Wakeful tracks why it is on (.manual vs .automatic), and which rules you have overridden:

• A rule becoming true turns Wakeful on with source .automatic.
• When the last rule you haven't overridden stops holding, it turns off again only if source is .automatic. Your manual session is never cancelled by a rule.
• Manually turning it off while a rule wants it on overrides that rule, so the app doesn't immediately re-enable itself. The status line names what is paused (e.g. "Sleep allowed — AC rule paused"), and Turn On (and the global shortcut) becomes Resume Smart Activation, which hands control back to the rules. Only rules that hold at that moment are overridden; the others stay armed. With the AC and battery rules both on, turning off at your desk and then unplugging lets the battery rule switch Wakeful back on.
• Each overridden rule re-arms on its own as soon as it stops being satisfied — so unplugging and replugging re-arms the AC rule even while an external display keeps another rule true. Enabling a rule arms it too.
• Starting a manual session overrides the rules that hold at that moment. When a timed session ends, a rule that held throughout stays overridden — so "Keep Awake For 15 minutes" really ends, even on AC — but a rule that became true during the session (you docked halfway through) takes over.

Global shortcut

Uses the Carbon RegisterEventHotKey API, deliberately not CGEventTap or NSEvent.addGlobalMonitorForEvents. The latter two would drag the user through an Accessibility / Input Monitoring permission prompt; RegisterEventHotKey needs no permission and no entitlement at all.

v1 ships three presets (⌃⌥⌘A, ⌃⌥⌘K, ⇧⌥⌘Z) rather than a recorder UI, and none is enabled by default — an app shouldn't claim a system-wide key combination without being asked.

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Build

Requires Xcode or the Command Line Tools (xcode-select --install).

git clone <your-repo-url> wakeful
cd wakeful
make install

make install builds in release mode, assembles Wakeful.app, ad-hoc code-signs it, copies it to /Applications, and launches it.

Other targets:

Command	Effect
make app	Build and sign into ./dist/Wakeful.app without installing
make app-universal	Same, from a universal arm64 + x86_64 binary
make run	Run the raw binary in the terminal (for debugging)
make uninstall	Quit, remove from /Applications, delete preferences
make clean	Remove build artifacts

To sign with a real Developer ID instead of ad-hoc:

make install SIGN_ID="Developer ID Application: Your Name (TEAMID)"

You can also just open Package.swift to work on it in Xcode, but note that Preferences and Launch at Login only behave correctly from the assembled bundle.

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Usage

Click the cup icon in the menu bar.

• Turn On / Turn Off — indefinite session. Same as the global shortcut. While Smart Activation is paused this reads Resume Smart Activation.
• Keep Awake For — 15m / 30m / 1h / 2h / 5h timed session, with a live countdown in the menu bar. Add 30 minutes to extend one in flight.
• Prevent — pick which assertions to hold. At least one is always held.
• Smart Activation — auto-enable while on AC, while an external display is connected, or while on battery above 20/50/80% (the battery rule only applies off AC, otherwise a charged laptop would satisfy it forever). Any display that isn't the built-in panel counts, so the rule also covers a closed laptop driving a monitor, mirroring to a projector, and a desktop Mac's only monitor. The submenu footer shows current conditions so you can see why a rule fired.
• Global Shortcut — off by default; pick a preset to enable it. Presets that clash with one of macOS's own system shortcuts (screenshots, Spotlight, Mission Control, input sources and the like, in System Settings ▸ Keyboard ▸ Keyboard Shortcuts) are marked and can't be picked; the preset you've chosen is checked when you pick it and at each launch. App Shortcuts, Services shortcuts and other apps' shortcuts can't be detected: macOS lets several apps register the same combination and delivers it to all of them, so if a preset already does something elsewhere, pick a different one. No global shortcut fires while macOS Secure Input is active — i.e. while a password field has focus.
• Launch at Login — install to /Applications first; the registration records the bundle path, so moving the app afterwards breaks it.
• Turn On at Launch — combine with Launch at Login for always-awake.

Hidden preference

The toggle and the global shortcut start an indefinite session by default (while Smart Activation is paused they resume it instead). To make them start a timed one:

defaults write com.github.wakeful.Wakeful defaultDurationMinutes -int 60

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Caveats

• Ad-hoc signing. make app signs with -, which is fine on the machine that built it. Anyone downloading a prebuilt binary would need a notarized build or a right-click → Open. Building from source sidesteps this entirely, which is why there are no releases.
• Power assertions cannot stop lid-close sleep. This is the one thing people expect and don't get. Assertions never override user-initiated sleep, so PreventSystemSleep keeps the Mac out of full sleep while idle on AC but does nothing when you shut the lid. Clamshell sleep can only be defeated with sudo pmset disablesleep 1, which has no public API and is deliberately out of scope here.
• PreventSystemSleep is AC-only. macOS ignores it on battery entirely.
• Login item approval. macOS may put the registration in a requiresApproval state the first time; the menu says so, and it's cleared in System Settings ▸ General ▸ Login Items & Extensions. SMAppService requires a code-signed bundle; ad-hoc signing is expected to satisfy that locally, but if Launch at Login errors out on your machine, a real Developer ID is the fix.
• Smart activation is coarse. "On AC" doesn't distinguish a charger from a dock. If you want "awake while on this specific display", that's a v1.1 problem.

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Roadmap

Deliberately out of scope for v1, in rough priority order:

1. Hotkey recorder UI instead of presets.
2. Per-app rules — stay awake while Zoom / a specific process is running. This is what people actually reach for after timed sessions.
3. A real Settings window (NSWindow), once the menu stops being enough.
4. Optional notification when a timed session expires.
5. Battery-drain guard: auto-release below a floor even during a manual session.
6. App icon + notarized release artifacts, if this is ever shared widely.

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License

MIT. See LICENSE.