Ergonomically sound and backed by actual usability research — bright reading surfaces reduce eye strain for dense text, even when the surrounding UI is dark.

Dark Mode for the operating system Light Mode for cognition-heavy tools.md

All right Peter — let’s make this boringly reliable, the way infrastructure should be.

There are three sane ways to keep per-app light mode enforced on modern macOS. They differ mainly in how “enterprise” you want to get.

I’ll walk from simplest → most robust, with opinions included at no extra charge.

---

Option 1 — Login script (best balance of power vs simplicity)

This is my default recommendation.

You create a small script that re-applies the settings every time you log in. If macOS resets anything during an update, the next login quietly fixes it.

Example:

#!/bin/zsh

# Force Calendar to Light Mode
defaults write com.apple.iCal NSRequiresAquaSystemAppearance -bool true

# Force Mail to Light Mode
defaults write com.apple.mail NSRequiresAquaSystemAppearance -bool true

Save it as:

~/bin/force-light-apps.sh

Make it executable:

chmod +x ~/bin/force-light-apps.sh

Then register it as a login item:

System Settings → General → Login Items → Add → select the script

That’s it.

No permissions prompts. No background daemons. No brittle hacks.

This survives reboots, OS upgrades, and mild Apple tantrums.

---

Option 2 — macOS Shortcuts automation (clean UI, slightly less durable)

If you prefer something visible and Apple-blessed: 1. Open Shortcuts 2. Create a new shortcut called: “Enforce Light Apps” 3. Add action: Run Shell Script

defaults write com.apple.iCal NSRequiresAquaSystemAppearance -bool true
defaults write com.apple.mail NSRequiresAquaSystemAppearance -bool true

4.	Automation tab →

“When I log in” → Run shortcut

This works well, but occasionally breaks after macOS updates until you re-approve permissions. Apple really likes consent screens.

---

Option 3 — LaunchAgent (most robust, most nerdy)

This is the “I don’t trust GUIs” option. macOS has a built-in scheduler called launchd. You can tell it:

“Every login, enforce this whether the user remembers or not.”

Create this file:

~/Library/LaunchAgents/com.whateveryouwant.force-light-apps.plist

Contents:

Label com.peter.force-light-apps

<key>ProgramArguments</key>
<array>
    <string>/bin/zsh</string>
    <string>-c</string>
    <string>
        defaults write com.apple.iCal NSRequiresAquaSystemAppearance -bool true;
        defaults write com.apple.mail NSRequiresAquaSystemAppearance -bool true;
    </string>
</array>

<key>RunAtLoad</key>
<true/>

Then load it:

launchctl load ~/Library/LaunchAgents/com.peter.force-light-apps.plist

From now on:

• login → enforced • reboot → enforced • macOS update → enforced • Apple engineers quietly sobbing → irrelevant

This is how admins do it.

---

My strong recommendation

For a single power user Mac:

Option 1 (login script) It’s transparent, readable, debuggable, and future-proof enough.

For “this machine must always behave correctly”:

Option 3 (LaunchAgent) That’s professional-grade macOS automation.

---

Useful bundle IDs

For convenience:

Calendar com.apple.iCal Mail com.apple.mail Notes com.apple.Notes Reminders com.apple.reminders Safari com.apple.Safari Preview com.apple.Preview

You can confirm any app with:

osascript -e 'id of app "Calendar"'

---

One important caveat

This trick forces Aqua (Light) UI chrome, but:

• email content rendering • calendar colors • message backgrounds

may still obey app-level settings.

That’s normal. You’re overriding the window appearance, not rewriting the app.

---

Final thought

You’ve essentially created:

Dark Mode for the operating system Light Mode for cognition-heavy tools

Which is ergonomically sound and backed by actual usability research — bright reading surfaces reduce eye strain for dense text, even when the surrounding UI is dark.

Apple accidentally shipped the perfect feature… and forgot to expose the checkbox.