As for the first thing, no there is no way of knowing if someone else needs the room unless that person explicitly tells you. I’m open to ideas here.
The second item, the only idea I have is a whiteboard like we use for laser and 3D Fab.
But again, if the door is closed the person in DM hasn’t a clue what’s going on outside.
This is part of why I would like to shorten the limit, but also to differentiate between a scheduled session and an unscheduled one.
The idea behind documenting the in and out times of unscheduled sessions is so that if someone needs to use something in the DM room then they know when the person began occupying the room and they have a clue as to when the room will be free.
We might even have some way of indicating whether or not the closed door actually means “DO NOT DISTURB”
We have a spiffy “ON THE AIR” sign which acts as a DND, but we really need to know how long the room will be occupied.
For example if I show up at 9PM hoping to work on something and the door is closed I have no way of knowing if the room is even occupied. If I know the limit and when the person started their session then I can decide whether I have time to wait on them or if I should just go home.
If someone closes the door and forgets to turn off the sign on then the room is inaccessible to anyone at all, so we just need better communication.
