@hongminhee洪 民憙 (Hong Minhee) 
i think the only support from fedify needed is basically like an environment variable or property for wherever identifiers are assigned or dereferenced
so for example if the service is mastodon.social it would assign identifiers using trwnh.com/mastodon/ as a base uri
it only needs to know which uris are already used, so it doesn't assign an id that's already in use.
@trwnhinfinite love ⴳ Actually, Fedify already supports this quite well. The actor dispatcher gives you full control over the actor's id—you can set it to any URL, including one on a custom domain. And since Fedify 1.4.0, there's a mapAlias() method that lets you handle WebFinger lookups for those custom URLs too. So running Fedify behind a reverse proxy that routes multiple hostnames, and assigning per-actor custom domain identifiers, should be achievable without any changes to Fedify itself.
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