- When viewing a room that you don't have permission to join, you shouldn't have an option to send a message.
- When viewing a room that you have permission to join -- but are not a member of -- sending a message should join the room (make you a member of the thread). Ideally, the UI button should change from "Send Message" to "Join Room" or something, but this could be a future version.
- When viewing a room that you are a member of, chat should work normally.