A modern programming language that makes developers happier.

kotlinlang

The Compose IDE Plugin is now in studio-master-dev (the AndroidStudio source code repository).  You can find it here: <https://android.googlesource.com/platform/tools/adt/idea/+/refs/heads/mirror-goog-studio-master-dev/compose-ide-plugin/>

You'll find that there isn't a whole lot there, since it mostly just delegates to the compose-compiler that you already found.

Also related are other things in the studio repository, like the Compose Designer: <https://android.googlesource.com/platform/tools/adt/idea/+/refs/heads/mirror-goog-studio-master-dev/compose-designer/>

To get started with the AndroidStudio source code, I think here is where I would start: <https://android.googlesource.com/platform/tools/base/+/studio-master-dev/source.md>