Oh hey, I'm the mirror universe version of you. I used to work in a semiconductor plant, writing Python code that controlled robot arms and electronic measurement instruments and so on. In my universe we used threads over blocking calls instead of async and it was exactly as bad as you might imagine.

>Having cancellation work smoothly is also pretty important to us

+10000. Threads don't have good cancellation semantics, so we never had a robust solution to the "emergency shutdown" problem where you need to tell all the running equipment to stop whatever they're doing and return to safe positions.

Every day I worked on that codebase I wished it had been async from the beginning, but I couldn't see a way to migrate gradually because function coloring makes it an all-or-nothing affair.