Overview

When a remote account is deleted in the fediverse, it sends out a Delete event (I believe). We should handle that event and delete the remote user from our DB whenever that happens.

It might also be helpful to add a shared inbox (TODO: create task), because the server gets pounded when there are multiple followees on the server that the now-deleted account was following.

Implementation

Delete the actor from remoteusers, and that remoteuser's ID from remotefollows and remoteuserkeys.

An actor Delete activity from Mastodon looks like this (partially):

...
"id":"https://mastodon.social/users/UserName#delete",
"type":"Delete",
"actor":"https://mastodon.social/users/UserName",
"to":["https://www.w3.org/ns/activitystreams#Public"],
"object":"https://mastodon.social/users/UserName"
...