Noise, light, and guests: the shared-room agreements to set early
Set a quiet window and define what it means: headphones, no speakerphone, and no bright overhead light after a stated hour. Decide how alarms, late returns, and work calls will work.
For light, agree whether one person can sleep while the other reads or works. A lamp, eye mask, and task light can solve most of it, but only if used consistently.
Guests need the clearest rule. Decide whether they can enter the bedroom, how much notice is needed, whether overnight guests are allowed, and where private conversations happen. Either roommate should be able to veto a guest in the room without drama.
Put these agreements in a shared note. They are basic care, not an attempt to control one another.