Social & federation
Cairn includes a full social layer:
- Follow other users and see their activities in your feed.
- Profiles with public/follower/private visibility.
- Kudos and comments on activities.
- Clubs with membership and moderation tools.
- Sharing via unguessable share links for individual activities.
Visibility
Every non-owner read goes through a single visibility choke-point. Owners see their own activities directly; everyone else sees only what your visibility settings project to them. This keeps private data private regardless of which endpoint is used.
ActivityPub federation (optional, beta)
Federation is currently beta: the protocol surface and remote-instance compatibility may still change between releases. Expect rough edges before enabling it on an instance you care about.
Enable CAIRN_FEDERATION_ENABLED to let your instance federate over
ActivityPub — follow and be followed across Cairn (and other compatible)
instances. It's off by default, and off means fully dormant: the home feed
does not surface remote activities the instance may have received earlier, the
web UI hides the "Federated" feed filter, and the public
GET /api/instance/features endpoint reports federation as disabled so clients
can hide it too. Flip the flag and restart to bring it all back.
Federation fetches and deliveries only reach public addresses: an address
guard refuses loopback, private, link-local, CGNAT (including the
100.100.100.200 cloud metadata endpoint) and every other IANA
special-purpose range, see
Outbound requests. For local
testing between instances on private addresses, additionally set
CAIRN_FEDERATION_ALLOW_PRIVATE_HOSTS=true; leave it off in production.