On macOS with FileVault enabled.

[pjbruce]

1. macOS 26.1.
2. FileVault enabled.
3. Add 'start-mydaemon.sh' in '/usr/local/outset/login-window'.
4. The contents of 'start-mydaemon.sh'

'#!/bin/bash
while ! /sbin/ifconfig en0 | grep -q "status: active"; do sleep 1; done

"/Library/Application Support/MyApp/MyDaemonExecutable" &

echo "$(date): Daemon launched" >> /var/log/mydaemon.log
' 

5. sudo chown root:wheel /usr/local/outset/login-window/start-mydaemon.sh
   sudo chmod 755 /usr/local/outset/login-window/start-mydaemon.sh
6. After restarting my Mac, "MyDaemonExecutable" does not run automatically on the login screen.

[bartreardon]

Correct, because the login window is not being displayed. With filevault on you see a filevault unlock window which looks like the macOS login window but isn't. The credentials entered here are used to log in to macOS and the login window is bypassed. If you use fast user switching or log out, then the macOS login window will display and the login-window script will run.

[gregneagle]

And to be clear: this is how macOS operates. There is a preference that you can set that disables the automatic login after FileVault unlock. The user unlocks FV with their credentials, macOS boots, and the Mac stops at the loginwindow, where the user must authenticate a second time. In this configuration, Outset login-window scripts would run at the loginwindow, but users must authenticate twice after reboot.

sudo defaults write /Library/Preferences/com.apple.loginwindow DisableFDEAutoLogin -bool true