For uri-identifiers that are non-webfinger identifiers, you'll see people say @wilkie.fyi
and this will mean it does discovery by looking at that page and discovering via content negotiation and/or links. This is useful for people who are creating content on sites that doesn't implement webfinger, for instance a blogging or photo posting site. They'll add Link tags instead and use a full URI. Basically: it is eas(ier) to syndicate that content without having to own the domain, but hard to add something to .well-known
.
I might be @example.org/wilkie
or even, dare I say, @mastodon.social/@wilkie
but it will still look like @wilkie
to humans. The same methods you are using to disambiguate, but hide the details to human beings, will still work here.
To disambiguate, in AS2, mentions and "hashtags" etc can be parsed universally using tag
:
{
"@context": "https://www.w3.org/ns/activitystreams",
"name": "A thank-you note",