In fact, I was quite inspired by Sublime Text, but not Atom/Electron.

You may check travis.yml (a bit hacky script but it's all I have for now).

It's built with JUCE, all-encompassing C++ framework like QT, but smaller (and with lots of audio processing classes).

Or Bitwig Studio - it has controller scripting API.

It only runs on tablets for now (i.e. requires a screen about 12x7cm at least). And yes, mobile versions are still quite incomplete, I put all my effort into desktop versions.

Aha makes sense. Where do I sign up for updates? :-)