There was (still is) a very popular program called BOME Midi Translator that did something similar - think of it like AutoHotKey but specifically for midi.
Back when I made heavy use of Kontakt libraries I got frustrated at the lack of an easy way to audition the patches (of which there could be hundreds on a single sampler). To get around it, I created a Bome script so when I pressed an unused button on my midi controller it would trigger a mouse click to advance to the next patch in my DAW and then send a note-on / note-off for C4 for half a second.
Made previewing the sounds much easier.
That may not seem like an obvious use-case when only thinking about a piano, but since it's mapping MIDI keys to commands, I guess it should be able — or at least no very far from being able — to map ergonomic MIDI controllers to actions that are not as ergonomic with the usual keyboard / mouse / trackball / touchpad most people use.
I wrote what I believe is a similar tool but with completely different goals initially: https://github.com/Arkanosis/smhkd ; I use it with a cheap MIDI controller (namely the KORG nanoKONTROL2) and was considering using another one with motorized faders (namely the Icon Platform M).
MIDI controllers are great for all kinds of non-musical things like: - setting the volume / balance / solo / mute for speakers / multiple headsets and mixing multiple applications (eg. using pactl); - setting the zoom level / brightness for camera / webcam (eg. using v4l2-ctl) ; - setting the source / brightness for monitors (eg. using ddcutil)…
Have you considered letting users define their own key mappings in a YAML config? That way people could customize it for their specific DAW workflow without touching the code.
Mapping MIDI keys to shell commands opens some fun automation possibilities. Nice and clean project.
Thanks for sharing it.