ActivityPub protocol specification and federation concepts. Use when working with ActivityPub activities, understanding federation mechanics, implementing protocol features, or debugging federation issues.
name federation description ActivityPub protocol specification and federation concepts. Use when working with ActivityPub activities, understanding federation mechanics, implementing protocol features, or debugging federation issues. ActivityPub Federation Protocol This skill provides understanding of the ActivityPub protocol specification and how federation works. For supported features and compatibility: See FEDERATION.md for the complete list of implemented FEPs, supported standards, and federation compatibility details. For implementation details: See AGENTS.md for transformers, handlers, and PHP code patterns. Core Concepts Three Building Blocks Actors
curl -H
"Accept: application/activity+json"
https://site.com/@username
curl https://site.com/.well-known/nodeinfo Common Issues Activities Not Received Check inbox URL is accessible Verify HTTP signature validation Ensure content-type headers correct Check for firewall/security blocks Replies Not Federated Verify inbox forwarding enabled Check addressing includes relevant actors Ensure inReplyTo properly set Follower Sync Issues Check Accept activities sent for Follow Verify followers collection updates Ensure shared inbox used when available Resources ActivityPub Spec ActivityStreams Vocabulary Project FEDERATION.md FEPs Repository