Slash Command

/messaging

This document explains how messages are delivered and processed in ActivityPub (Client-to-Server).

Install

Run in your terminal

npx claudepluginhub utakatakyosui/c2lab --plugin activitypub-c2s

Namespaceactivitypub-c2s/guides/

Stats

Parent Repo Stars3

Parent Repo Forks2

Last CommitFeb 17, 2026

Actions

This document explains how messages are delivered and processed in ActivityPub (Client-to-Server).

Outbox: The endpoint where a user posts Activities (via POST). It can also be read (via GET) to see the user's public activities.
Inbox: The endpoint where a user receives messages (from other servers or users). In C2S, clients read from here. In S2S, other servers POST here.

When a server receives an Activity in the Outbox (C2S), it must perform specific side effects:

Validation: Check authentication, authorization, and object structure.
ID Generation: Assign a unique URI to the new object (if applicable, e.g., on Create).
Persistence: Save the object/activity to the database.
Federation (Delivery):
- Analyze to, cc, and audience fields.
- Resolve Inboxes for recipients (handling Shared Inboxes for efficiency).
- Deliver the Activity to external servers (S2S).
Collection Updates: Update the user's outbox, followers, likes, etc., as appropriate.