reply-flow-with-webfinger

reply-flow-with-webfinger.md

For a given target post activity pub id url, say: https://example.com/@alice/posts/9b905f9a-f607-4d97-8b6a-e4f212b07561

1. Prompt for the user's fediverse identity, say: @bob@bobsdomain.com
2. Issue a webfinger request to find the redirect url:

GET https://bobsdomain.com/.well-known/webfinger?resource=acct:bob@bobsdomain.com

200 OK
content-type: application/jrd+json; charset=utf-8

{
  "subject": "acct:bob@bobsdomain.com",
  "aliases": [
    "https://bobsdomain.com/@bob",
    "https://bobsdomain.com/users/bob"
  ],
  "links": [
    {
      "rel": "http://webfinger.net/rel/profile-page",
      "type": "text/html",
      "href": "https://bobsdomain.com/@bob"
    },
    {
      "rel": "self",
      "type": "application/activity+json",
      "href": "https://bobsdomain.com/users/bob"
    },
    {
      "rel": "http://ostatus.org/schema/1.0/subscribe",
      "template": "https://bobsdomain.com/authorize_interaction?uri={uri}"
    }
  ]
}

3. Use the url template from the object with "rel": "http://ostatus.org/schema/1.0/subscribe" and redirect the user to it, replacing {uri} with the url encoded version of the target post activity pub id url

GET https://bobsdomain.com/authorize_interaction?uri=https%3A%2F%2Fexample.com%2F%40alice%2Fposts%2F9b905f9a-f607-4d97-8b6a-e4f212b07561

4. This will prompt the user to login, then display the target post on that server's UI. The user will be able to favorite, reply, follow, etc from there