@silverpill yes, I was thinking of the nomadic identity aspect when I said that.
So, for GoAP: a user wants to upload an image, it can specify recipients, the client builds an Image AP object out of that (including a reply collection) and wraps it in a Create collection, sends it to the server (C2S).
Server saves Image locally, creates all collections for the Image that are not empty in the Image (like replies, likes, shares, etc) adds it to outbox of user's Actor, adds it to local follower's Inbox or sends it to remote followers Inbox (S2S). If it's in reply to something(s) loads the object(s) and disseminates it to the recipients.