On Wed, 2024-05-29 at 13:02 +0000, Stephen Paul Weber wrote:
A 1:1 chat *is* a groupchat with two participants. It's not a MUC but as you quoted the XEP says it doesn't have to be.
The XEP says that clients can assume it is MUC, but that it doesn't have to be. It has to be a "chatroom of any particular groupchat protocol". While you are free to argue that 1:1 chats are groupchats of a group of two and therefor regular chat messages form a groupchat protocol, I doubt it was intended that way by the authors (neither in XEP-0402 nor in any other XEP). What makes it still clear in the XEP, is that the bookmark must be of a *chatroom* of a groupchat protocol, and a regular user JID is certainly not a chatroom. The XEP is clearly hinting and a successor of MUC (like MIX) being potentially using it. Not that you use it for 1:1 chats. If there is really confusion about this and the word groupchat and you're not trying to make this up to retrofit this XEP, I suggest we put some official definitions of terms popularly used in XEPs up somewhere.