Optionalmembership_Role of the member within the thread. One of "owner" (the user who created or was granted ownership) or "member" (a regular participant).
OptionalthreadID of the thread this membership belongs to (thr_...).
OptionaluserFull user object for the member (usr_...). Present when the association is preloaded; null otherwise.
A user's membership record in a thread, capturing their role and full user profile.