RunClosed

A macOS menu-bar utility for people who dock a laptop to external displays: toggle displays on/off, dim the ones macOS can't dim, pick resolutions, and keep the machine awake with the lid closed — from one popup with real toggles.

Formerly DisableScreen (the Python app in this repo's history); the product was rewritten in Swift and renamed. The Python implementation is kept in-tree as the audited baseline (see Repository layout).

Features

• Toggle each display on/off from a popup switch (SkyLight under the hood). The last active display is protected: its switch is greyed out.
• Brightness slider per display — native brightness for the built-in panel, a software-dim overlay for external monitors whose DDC path macOS ignores on Apple Silicon.
• Resolution picker listing the modes reported by CoreGraphics, with a read-back that verifies the mode actually changed.
• Keep awake with lid closed — flips the pmset disablesleep flag with an ownership model (see Safety model).
• Open at login via SMAppService.
• Localized: English (base) and French.

Requirements

• macOS 14 (Sonoma) or later, Apple Silicon (Intel compiles, untested)
• Xcode 16+ / Swift 6 toolchain (build only)
• No third-party dependencies

Build

bash scripts/build-runclosed-app.sh
# → build/RunClosed.app

Signing: the script ad-hoc signs by default (-). For the login-item approval flow and distribution, pass a Developer ID:

SIGN_IDENTITY="Developer ID Application: Your Name (TEAMID)" \
  bash scripts/build-runclosed-app.sh

Test:

swift test        # 295+ assertions across Core / MacSystem / Persistence / UI logic

Install

cp -R build/RunClosed.app /Applications/
open /Applications/RunClosed.app

The app lives in the menu bar (no Dock icon). Left-click opens the popup, right-click opens a small menu (Refresh / Display Settings / Quit).

Optional: passwordless lid control

The "keep awake with lid closed" toggle writes pmset -a disablesleep. Add a sudoers drop-in so the app can do it without a prompt:

sudo tee /etc/sudoers.d/runclosed-pmset >/dev/null <<'EOF'
%admin ALL=(root) NOPASSWD: /usr/bin/pmset -a disablesleep 0, /usr/bin/pmset -a disablesleep 1
EOF
sudo chmod 0440 /etc/sudoers.d/runclosed-pmset

Without this rule the toggle fails fast and honestly (it never prompts — the app calls sudo -n, and the read-back is what decides success).

State lives under ~/Library/Application Support/RunClosed/:

leases.json             # bounded keep-awake leases (CLI wrappers)
owned_displays.json     # displays we disabled (re-enabled at next launch)
owned_lid.json          # lid flag ownership record (boot-scoped)

Safety model

This app mutates global system state (display topology, a root-owned power flag), so the invariants are the interesting part:

• Read-back decides. A native call returning 0 is not success; the observable outcome is. All mutations carry a typed result (verified / failed / unknown).
• UNKNOWN ≠ OFF. An unreadable state is never rendered or treated as OFF.
• Ownership. The lid flag is restored on quit only when we set it on this boot, proven by a persisted record + read-back. A flag owned by another boot is kept as recoveryPending and never silently flipped (fail-closed).
• Last-display guard. Disabling the only active display is refused at the moment of the effect, not at render time.
• One target per command. A brightness command for display A never touches display B.

Repository layout

Sources/
  RunClosedCore/         # pure logic: policies, models, lease engine (no AppKit)
  RunClosedMacSystem/    # macOS surfaces: CoreGraphics, SkyLight, pmset, SMAppService
  RunClosedPersistence/  # on-disk state (atomic writes, schema-versioned)
  RunClosedApp/          # presentation logic (view-model + text renderer)
  RunClosedMenuBar/      # the menu-bar app (AppKit)
  RunClosedHelper*/      # privileged LaunchDaemon skeleton (registration only)
  runclosed/             # CLI: status, displays, doctor, run, disable/enable,
                         #      lid-stay-awake, restore, login-item, helper
tests/                   # Swift test suites
main.py, launcher.m,     # legacy Python app (audited baseline, kept in-tree)
build.sh, test_e2e.py
docs/mutation-inventory.md  # every external state mutation of the legacy app
DECISIONS.md             # architecture decision records (ADR table)
PROGRESS.md              # tranche-by-tranche delivery log
TEST_RESULTS.md          # what was tested, with commands and outcomes

Known limitations

• Display disable/enable uses the private SkyLight API (SLSConfigureDisplayEnabled). Not App Store-submittable; fine for direct distribution. Notarization does not change this.
• The two-display enable/disable path has not been exercised end-to-end on hardware with a single screen (the last-display guard is what runs there).
• External brightness is a software overlay, not DDC. The UI says so.
• The privileged helper daemon ships as a registration skeleton (no XPC yet); the day-to-day app uses sudo -n pmset + the sudoers rule instead.

License

MIT — see LICENSE.

Copyright (c) 2026 Benjamin Belaga.