I attempted to read that code in order to glean information about how it communicates back to GitHub about progress etc. The goal was to make a new runner. I ran for the hills, fast.
Sadly that's an emulator of the entire stack, I wanted to do the runner part only (the goal being to end up with a sane self-hosted runner replacement).
I’m not sure if it’s open source but the actions-runner-controller project maintains a slimmed down version of the runner image that might be worth looking at
Sounds like most Microsoft projects to be honest. Not a lot of them can be highlighted as the pinnacle of software engineering, including their GitHub Actions implementation.
No kidding. I have been in the bowels of EF at work, and it has led me to (likely not independently) coin "encapsulation infatuation". Bloody hell, what a beautifully decoupled mess. The only way to make sense of a single thing is to step through/into each line of code.