I occasionally undock my Macbook to take it to work, or out for a weekend, etc. I have the battery settings setup to automatically dim the screen when on battery, and this works great. Unfortunately Apple doesn’t seem to include an option to max the screen brightness when connected to power again, so for a while on re-attaching to my Studio Display I was manually adjusting brightness back to max to (roughly) match the output between the two panels.
I looked at a number of options to accomplish this - Building something myself as a shell script, shortcut buttons, or other paid products like Power Manager, however I came across Stecker while doing my research on launch daemons to handle this and decided that simple might be the best.
Stecker is an Apple silicon native app that allows you to run shortcuts from the Apple Shortcuts app on connecting/disconnecting various USB devices. It looks for IOKit notifications for the triggers, and it’s incredibly lightweight. In my case, the only time I really cared about maxing the brightness was when my Studio Display was connected, so it was pretty trivial to just setup a shortcut for 100% brightness and run it on connecting to the studio display. Voila, problem solved.
Now, it won’t detect me just plugging in a USB-C charger, which means I can’t automate this for every scenario here. However I’m only really using this to match display brightnesses - On the go just charging the Macbook it doesn’t matter as much. I’d love to see the developer extend this to also detecting power source for the additional flexibility, but that’s more of a nice to have.
Anyway, check out Stecker - It’s free! Lots of flexibility with it too!