the official conventions also discourage some of things we’re very opinionanted about, like favoring expression bodies and hinting Unit return types 😄

Yes, and that’s fine. I don’t think those are part of the code style, though, and are rather intentions (from an IntelliJ perspective). Is this something that should be mentioned in the Contributing.MD? Do you use the Kotlin code style conventions in IntelliJ? Or more importantly, do you use IntelliJ or something else?

we use intellij's baseline with a couple of tweaks for 2 spaces everywhere IIRC

I noticed the 2 spaces almost immediately. I’ve been doing Java/Kotlin work for so long that it felt ‘weird’ 😉