AppleScript saved as application doesn't execute whole script when argument is passed
It looks like passing arguments to an AppleScript saved as an application has become broken at some point. I accomplished my task by using Automator to create an equivalent new Application that makes use of an Action &gt; Utilities &gt; Run Shell Script:

open -a Firefox
sleep 1
lsappinfo setinfo -app Firefox ApplicationType=UIElement
osascript -e 'tell application "System Events" to tell process "Firefox" to set value of attribute "AXFullScreen" of first window to true'
sleep 0.5
for f in "$@"; do open -a Firefox "$f"; done


I set the shell script Shell: to /bin/sh and Pass input: to as arguments, save it as "Firefox Full Screen" in /Applications, change its icon as explained here and add it as an exception in System Preferences &gt; Security &amp; Privacy &gt; Privacy Tab &gt; Accessibility.

I then can run any of the following and it works as expected:


open -a "Firefox Full Screen"
open -a "Firefox Full Screen" --args "https://google.com"
open -a "Firefox Full Screen" --args "https://google.com" "https://twitter.com"


I'm using this coupled with the following userChrome.css to both evade a well known issue with the macOS menu bar on full screen applications and another long standing address bar and tab auto-hide bug that Firefox have with macOS native full screen.

userChrome.css

#navigator-toolbox[inFullscreen] {
    position: relative;
    z-index: 1;
    height: 3px;
    margin-bottom: -3px;
    opacity: 0;
    overflow: hidden;
}

#navigator-toolbox[inFullscreen]:hover {
    height: auto;
    margin-bottom: 0px;
    opacity: 1;
    overflow: show;
}

#content-deck[inFullscreen]{
    position:relative;
    z-index: 0;
}


For a generic approach, check my other answer.

TIP


Firefox, by default, does not have any issue on Linux or Windows to auto-hide address bar and tabs in full screen as expected. With that said, I grabbed this userChrome.css from my ArchLinux setup. I use it on i3 and sway tiling window managers, with all the [inFullscreen] removed, to get address bar and tabs to auto-hide in normal bordless windows.