The bug is currently being reviewed by Albert, because the thought should indeed be removed when hearthlings are outside buildings too, so that might get fixed soon.
We don’t have a list of requirements, since this is something that still needs to be balanced and can change in the future.
Besides having windows, the only other tip that I have at the moment is don’t let hearthlings wander close to doors for too much time, keep them busy (I’ve noticed sometimes they like to chat around the door of the dining hall after eating, and they sometimes end up feeling cramped).
As you can see in the images I posted, the area they observe for calculating this is adjusted and expands towards open spaces. I’ve tested again on the tiny cottage and they don’t always get the ‘cramped’ thought, might be depending on the time they take to sleep or something; I’ve seen their area expanding towards the window and the door and not becoming yellow/red.
Don’t worry about the objects, the base of the area is at the level of the hearthlings eyes : worry about the space between the walls (if the hearthling spends too much time on the inner corner of a building and the room does not have open spaces / windows / doors nearby then yes, it might get cramped). Since the thought appears a little after they’ve felt cramped (for a certain time) you might think it immediately relates to the space they are currently in, but due to this bug, it might have happened way before (maybe when they were building, or mining…).
After this bug gets fixed, let’s compare how often they feel cramped again. Try to make rooms of all sizes and send us the savefiles, that way the tuning will be easier. We’re concerned about this and we also want to be able to have small cozy houses that make your hearthlings happy