Webmention endpoint

This instance publishes site.standard.document records from webmentions: POST a source and a target here and the linking page becomes a document record in the target publication owner's atproto repository. What identifies the publication is the request's target, not the URL that received the request, so this one endpoint serves every publication registered here.

The endpoint is https://atmosphere-bridge.services.alioth.systems/.well-known/webmention, announced in this document's Link response header and in its <link rel="webmention"> element — the same advertisement every publication page carries in its own head. An X-Webmention-Delete: true request retracts the record that page was published as — and only when the page's own state has given the mention up: the page is gone (404 or 410), or it is served and no longer links here. A page that still links this publication cannot be retracted by anyone, and a source on another host is refused.