Is "Both" an option? Like have a list of people who are always allowed but having the option to invite outsiders?
Yeah that'd be good. I kinda underestimated the complexity of room access control I think. What I'm going to go for at the moment is:
1. Rooms can either be public/private.
2. Private rooms can have a list of always-permitted users.
3. Private rooms can have an option to "allow invitations" to be sent from either users/mods/admins/owner.
I think that meets all the requirements?