I know you said no passive aggresive, but maybe a door hanger that says "don't disturb" might do the work? Or actually start the topic in more calm way?
...That’s probably a good idea, but I’ve been putting up with that behaviour for a while and at this point I’m not sure if I could have it in myself to remain calm while broaching this subject with her xD (And, what do you even say without sounding antisocial? Or without making the person paranoid when they actually have some urgent business to talk to me about?)
even the people i lived with at uni knew that if you want something you either wait until you meet the person in the kitchen or you KNOCK and wait until they let you inside their room... and i lived with a bunch of caveborn dudebros -_-
It’s not like she just walks in without knocking (she wouldn’t be living in this flat if that was the case); she does knock on the door and waits until I say “come in”, but my problem is the frequency xD (Like, it’s weird, b/c she also lived in a dorm when she was at uni, so it’s weird that in those five years she hasn’t learnt to respect people’s space)