The monobuild combines the IntelliJ Community project and the Android Studio project into a single combined IDE build. This can be helpful when working on features that span both projects (since it quickens the edit/compile/debug cycle significantly).
Run ./generate.py and then open this directory in IntelliJ.
From there you can launch the Android Studio run configuration as usual.
If you change the project structure (e.g. module dependencies) of Studio code, then you will need to re-run generate.py for those changes to take effect in the monobuild.
If you change the project structure of IntelliJ Platform, then you will need to run generate.py with flag --rebuild-intellij-module-descriptors (or update intellij-sdk prebuilts).
The generate.py script is expected to break occasionally, such as when there are new conflicts between Studio/IntelliJ configuration files. Please spend a few minutes debugging to see if it is an easy fix. Otherwise, file a bug.
See the IntelliJ README for IDE build configuration tips.
To test code changes in generate.py, you should diff the generated output against previous runs. You can utilize git diff --no-index <before> <after> for this.
You can use the “Load/Unload Modules” action in the IDE to exclude any broken modules (assuming these modules are not needed by the run configurations you care about).