macOS actually does that somehow indeed. Not exactly, but it does prevent charge when it “guesses” the computer will stay plugged in for a long time based on previous usage.
Which isn't a solution, I just want a toggle so I know it works. I don't want to train some hidden logic so it correctly guesses what I want based on what someone on the other side of the planet assumed my usage pattern looks like.
…for you. For me, I am perfectly content with the algorithm deciding, and then me, deciding when I know I am going to be disconnected outside of my normal usage pattern…telling the machine to charge it to a 100%.