Thanks for the quick reply, and for the project as well. It is a life changer!!!

I checked the BetterDisplay shortly after commenting, and I was so glad I found it. However it reaches only 80% of my use-case, so I would like to make this feature request for BetterDisplay instead.

I am currently using the CLI like this to display volume in Sketchybar (ref)

elif command -v betterdisplaycli 2>&1 >/dev/null; then
  if [ "$VOLUME" = "missing value" ]; then
    ALTERNATE_VOLUME=$(betterdisplaycli get -feature=volume -value -displayWithMainStatus | bc)

    MEGA=100

    if [[ $ALTERNATE_VOLUME =~ "." ]]; then
      VOLUME=$(bc -l <<<"${ALTERNATE_VOLUME}*${MEGA}" | bc)
      VOLUME=$(echo "$VOLUME" | cut -d. -f1)
    fi

    MUTE=$(betterdisplaycli get -feature=mute -value -displayWithMainStatus)

    if [ "$MUTE" = "on" ]; then
      VOLUME="0"
    fi
  fi
fi

However, I currently have to run the script as a cron job since I am not sure how to catch events from BetterDisplay and run a shell command after I change volume.

For example, in aerospace, I have this to trigger an event inside sketchybar (ref)

exec-on-workspace-change = ['/bin/bash', '-c',
    'sketchybar --trigger aerospace_workspace_change'
]

And I was hoping BetterDisplay/MonitorControl also had something like this. In the documentation I can find a way to catch the event in a Swift application. If there is a simpler alternative to that, I would appreciate that a lot.

Oh, I see - so you need sketchybar to do something when you change the volume in BetterDisplay? Well, you can do it in a somewhat roundabout way - you can create an integration control for volume, use shell script as integration method, add your command to trigger sketchybar and also add a CLI command to directly adjust the DDC volume (by addressing the right VCP). By setting up integration controls for volume and mute, the app's volume slider, keyboard etc will use that instead of DDC volume (which you can as well turn that off under DDC Features).

But I can add a feature to have built-in controls send shell script or URL events (the app now does distributed notifications).

Let's continue this discussion here: waydabber/BetterDisplay#4320