Not to toot my own horn (OK, I lie: totally to toot my own horn), I just found out about a non-trivial contract change in the Nova API because one of my extension tests abruptly failed right after updating, with no changes in any code of mine .
I wasn’t entirely sure how far I wanted to carry this thing, but I’ve pretty much set my mind to make this a kinda meta extension for extension development (tentatively named NovaNova) now. Talk of a motivator.