Here's you FEP:
# FEP-ce05: Discovering ActivityPub object from an HTML document
## Summary
## Content negotiation
If HTML document has an ActivityPub representation and request has an Accept header containing application/activity+json or application/ld+json; profile="https://www.w3.org/ns/activitystreams" media type, the server SHOULD return a response with HTTP 308 Permanent Redirect status code and a Location header containing ActivityPub object ID. The server MAY use 302 Found status code.
If ActivityPub object has an HTML representation and request has an Accept header containing text/html media type, the server SHOULD return a response with HTTP 308 Permanent Redirect status code and a Location header containing an URL of HTML document. The server MAY use 302 Found status code.
## Copyright
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
To the extent possible under law, the authors of this Fediverse Enhancement Proposal have waived all copyright and related or neighboring rights to this work.
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