trwnh

Mastodon protocol contains many departures from ActivityPub specification, mostly in the form of additional requirements.

The point is that the following is a non-zero list of differences. Compliant ActivityPub gets dropped by Mastodon all the time. I'm probably missing things here, since there are a ton of issues I haven't looked through, but this is what I could find just reading through the spec. I maintain that reading https://docs.joinmastodon.org/spec/activitypub/ is more useful than reading https://www.w3.org/TR/activitypub/ if your goal is to talk to Mastodon.

Mastodon protocol's differences from ActivityPub

• The primary unit of content is a Note, not an Activity.
• You MUST compact your documents against the same context as Mastodon's internal context. URIs are not expanded to become unambiguous.
• Actors MUST have a type of Person, Group, Organization, Application, Service. (AP says that actors can have any type.)
• Actors MUST have a preferredUsername (instead of MAY). Performing a WebFinger

trwnh

the Signature-cid-v1-subject auth-scheme

Authorization: Signature-cid-v1-subject \
	signature=sig1 \
	cid="https://cid.example/"
Signature: sig1=::
Signature-Input: sig1=();keyid="https://key.example/"

trwnh

[
  [
    {
      "a": 6
    },
    "Esc",
    {
      "x": 0.25
    },
    "F1",

trwnh

/*sidebar (expanded)*/
.wT, .aeN {min-width: 320px !important;}
.wT { /*label list*/
    background: rgba(0,0,0,0);
    color: white;
}
.bsU { /*unread counter*/
    background: red;
    color: white;
    padding: 0 0.5em;