@boris @feditips I think you're talking of two different things here:
1) client behaviours when opening links (URLs) in the app, such that the user gains an interact-able experience when visiting links to other fedi software.
2) Behaviour for fetching link previews (these are currently handled by fedi implementations, but does need a way to communicate an initial value via activitypub, but has security risks). Client's probably shouldn't be requesting link previews directly from the URL.