Add Bovine reference to Portable Identity for ActivityPub

site/posts/2023-05-01-activitypub-portable-identity.md

@@ -77,6 +77,8 @@ I am not familiar enough with the Mastodon codebase to say whether moving to the
 
 There is, to the best of my knowledge, only one single ActivityPub project that supports multiple domains: [Takahē](https://github.com/jointakahe/takahe). Multiple accounts across different domains being backed by the same host doesn't get us all the way to portable identity. But the architectural decisions required to support it go a long way towards that vision. I have not taken the time to trawl through the code and work out if it's actually using the domain to look up AP objects in its database or if it, like Mastodon and others, is still just extracting the database ID from a path component and using that for the lookup. Either way, by virtue of supporting multiple domains already, I think Takahē is much closer to reaching this vision.
 
+**Update:** There is an AP implementation, [Bovine](https://codeberg.org/bovine/bovine/), which stores and identifies AP objects by their AP identifier, which goes a long way towards making this implementation of portable identity possible.
+
 Migrating existing accounts and content to portable identities, though, is an open and much harder question. The identifier for just about every AP object that's already out there specifies the host. Making those objects portable would mean either making existing domains identity resolvers rather than hosts (not feasible) or getting every instance to update all of its references to the moved objects (basically where we're at now, and it's not feasible either). This is the biggest question regarding this approach, and I readily admit that I do not have a good answer to it.
 
 ### Technical Miscellanea