ExternalDisplayTools is a small macOS app for turning the notch into something useful instead of leaving it empty.

I built it as a menu-bar style accessory app that keeps a notch view alive in the background, shows Now Playing artwork and music bars, surfaces battery and charging activity, and accepts external requests through a custom URL scheme.

• Keeps a notch window pinned at the top of the main display
• Shows the current music state when nothing else is taking over
• Accepts external notch requests through notch://show
• Displays battery and charging activity in the notch
• Supports Bluetooth, keyboard remapping, haptic feedback, and launch-at-login settings
• Runs as an accessory app, so it stays out of the Dock in normal use

• macOS
• Xcode
• Accessibility and Input Monitoring permissions if you want keyboard remapping to work

1. Open ExternalDisplayTools.xcodeproj in Xcode.
2. Build and run the ExternalDisplayTools scheme.
3. Open the app settings if you want to change launch-at-login, haptics, battery notifications, or charging animation behavior.

If you want the app to start automatically, turn on Launch at Login in Settings. The app registers itself with SMAppService when that setting changes.

The app registers a custom URL scheme:

notch://show?duration=5&content=text:Hello
llo

The parser is strict about the request shape:

• duration is required and is clamped between 1 and 60 seconds
• content is required
• left is optional
• right is optional
• Only one external request can be active at a time
• Requests are ignored while the screen is locked or the screen saver is active

content supports:

• text:Your message
• image:https://example.com/image.png
• gif:file:///tmp/animation.gif

right supports:

• text:LIVE
• icon:bolt.horizontal.fill
• image:https://example.com/image.png
• gif:file:///tmp/animation.gif

left must be a bundle identifier for an installed app on the current machine.

Show a short text message:

open "notch://show?duration=6&content=text:Hello from the notch"
ch"

Show text with a right-side label:

open "notch://show?duration=5&right=text:LIVE&content=text:Recording"
ording"

Show an image:

open "notch://show?duration=8&content=image:https://example.com/pic.png"
ng"

The Settings window is split into a few simple sections:

• General: launch at login and haptic feedback
• Battery: battery notifications and charging animation
• Keyboard: key remapping and permission checks

Keyboard remapping needs Accessibility and Input Monitoring permissions. If those permissions are missing, the app shows the prompt in Settings instead of trying to guess.

This started as a practical macOS experiment, not a polished product. The code leans on SwiftUI, AppKit, and a small amount of window delegation to keep the notch pinned where it belongs.

The current implementation also keeps the notch responsive to screen lock state, screen saver activity, and wake/display changes so it does not drift out of place after the machine sleeps or the display setup changes.

• External requests do not queue up; they are ignored while one is already active
• Invalid URLs are rejected silently
• The left-side app icon only works if the bundle identifier resolves on the current machine
• The notch content is intentionally constrained, so oversized content will clip or shrink to fit

• Notch-implementation.md
• ExternalDisplayToolsApp.swift
• ExternalNotchRequestManager.swift
• SettingsView.swift