This remains one of my least favorite features of #ActivityPub.
1. It violates fundamental type safety principles.
2. "without authentication" means that it needs to be accessible to random people on the internet if read literally, and evidently changing this (along with "we should all require transport layer security") are controversial opinions in fediverse development.
3. Literally everything about that Note makes me die inside.
4. Yet another example of how "there are no servers in ActivityPub" is undermined by the spec. Because this entire concept and its use cases assume a server. "There are no servers" has always been a fiction, but this illustrates the tension.
5. It is the kind of thing that could be better implemented by using actors, but the protocol is unwilling to take that route for how to implement features.
![5.6 Public Addressing
In addition to [ActivityStreams] collections and objects, Activities may additionally be addressed to the special "public" collection, with the identifier https://www.w3.org/ns/activitystreams#Public. For example:
EXAMPLE 10
{
"@context": "https://www.w3.org/ns/activitystreams",
"id": "https://www.w3.org/ns/activitystreams#Public",
"type": "Collection"
}
Activities addressed to this special URI shall be accessible to all users, without authentication. Implementations MUST NOT deliver to the "public" special collection; it is not capable of receiving actual activities. However, actors MAY have a sharedInbox endpoint which is available for efficient shared delivery of public posts (as well as posts to followers-only); see 7.1.3 Shared Inbox Delivery.
NOTE
Compacting an ActivityStreams object using the ActivityStreams JSON-LD context might result in https://www.w3.org/ns/activitystreams#Public being represented as simply Public or as:Public which are valid representations of the Public collection. Implementations which treat ActivityStreams objects as simply JSON rather than converting an incoming activity over to a local context using JSON-LD tooling should be aware of this and should be prepared to accept all three representations.](https://media.hachyderm.io/media_attachments/files/116/889/985/405/101/811/original/d247a1691816af10.jpeg)
