I believe the W3C should reconsider splitting the #ActivityPub Recommendation into three documents: Core/Shared requirements, S2S (Server-to-Server, "social/federation protocol"), and C2S (Client-to-Server, "social API"). I think it would reduce developer confusion and help them focus on requirements that are relevant to their work (typically, S2S/Core). It would also allow C2S to be improved independently so that more developers might consider using it.