kb-fediverse-activity-intents

The WebFinger URL template mechanism standardizes how Fediverse servers advertise machine-readable endpoints for cross-server social interactions. It solves the problem of broken remote interactions by allowing servers to discover activity intents for actions like following, liking, and sharing content across different instances.

To implement a cross-server follow button using ActivityPub, use WebFinger to publish activity intents as RFC 6570 URI templates. Your website can then direct users to perform social actions like Follow or Like on remote content using their home server account without leaving the page.

Standard activity intents for social web interactions include Follow, Like, Announce, and Create. The Create intent specifically handles content composition, while an Object intent exists for remote object retrieval. These intents are advertised via WebFinger responses to enable seamless cross-server actions.

Yes, FEP-3b86 supports content composition through the special Create intent and remote object retrieval through the Object intent. It defines workflow callbacks for these actions and provides implementation guidance for both home servers publishing intents and remote servers consuming them.

Security considerations for cross-server social interactions include protecting against CSRF attacks and preventing open redirects. Implementations must carefully validate WebFinger URL templates and activity intent callbacks to ensure remote actions do not expose users to malicious redirection or cross-site request forgery vulnerabilities.

Remote interactions break between different Fediverse servers because servers lack a standardized way to discover each other's interaction endpoints. Activity Intents (FEP-3b86) addresses this by using WebFinger URL templates to publish machine-readable interaction paths, evolving from older oStatus standards to current ActivityPub practices.