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a@trwnh@socialhub.activitypub.rocks (2026-05-12 12:29:34)
Also available at:

https://lists.w3.org/Archives/Public/public-swicg/2026May/0017.html
https://lists.w3.org/Archives/Public/public-socialweb/2026May/0002.html
Context:

https://github.com/w3c/activitystreams/issues/595
https://lists.w3.org/Archives/Public/public-swicg/2026May/0015.html
https://lists.w3.org/Archives/Public/public-socialweb/2026May/0001.html
In earlier discussion regarding how people expect a Link to work, it seems to me like we uncovered a sort of X-Y issue. Hong Minhee, who develops the Fedify library, indicated that overriding the term definition of "href" to be a literal string instead of a URI reference was intended to avoid dereferencing ids that don't have AS2 representations. The inherent assumption is that any id will have an AS2 representation, but this isn't a valid assumption, because non-AS2 resources exist on the Web (and in fact vastly outnumber AS2 resources).

Across the specification documents for AS2-Core, AS2-Vocab, and AP, the only remotely relevant language I could find was in AP Section 3.2 "Retrieving objects":

The HTTP GET method may be dereferenced against an object's id property to retrieve the activity. Servers MAY use HTTP content negotiation as defined in [RFC7231] to select the type of data to return in response to a request, but MUST present the ActivityStreams object representation in response to application/ld+json; profile="https://www.w3.org/ns/activitystreams", and SHOULD also present the ActivityStreams representation in response to application/activity+json as well. The client MUST specify an Accept header with the application/ld+json; profile="https://www.w3.org/ns/activitystreams" media type in order to retrieve the activity. Servers MAY implement other behavior for requests which do not comply with the above requirement

From this, we can see that there is no explicit requirement for every id in an AS2 document to be dereferenceable with an AS2 representation. At most, we can say that ActivityPub requires "c
---Reply---
silverpill@silverpill@mitra.social (2026-05-12 23:13:23)
The inherent assumption is that any id will have an AS2 representation, but this isn't a valid assumption, because non-AS2 resources exist on the Web (and in fact vastly outnumber AS2 resources).

Every id value is expected to be an identifier of an ActivityPub object. When it resolves to something else, like an HTML document, we conclude that the identifier is not valid.

Fediverse != Web

Hong Minhee, who develops the Fedify library, indicated that overriding the term definition of "href" to be a literal string instead of a URI reference was intended to avoid dereferencing ids that don't have AS2 representations.

@hongminhee So, Fedify returns a string and delegates the decision to the user?

Sounds reasonable. By default, hrefs do not point to ActivityPub objects.