A remote handle on its own domain, once that domain's WebFinger agrees (FEP-2c59)

An account on a server whose handles are not its host's (Mastodon's LOCAL_DOMAIN apart from WEB_DOMAIN) showed as
user@host. The actor's `webfinger` names the handle; its domain is kept once WebFinger there points back to the actor,
and asked again when the name changes. A persona's blocked servers match a handle's domain as well as the actor's host,
as the lists Mastodon exports name handles' domains.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

docs/INTEROP.md

@@ -36,7 +36,8 @@ Priorities, used throughout:
   - Up to 16 are kept. Mastodon drops anything past 4; Pixelfed albums and Threads carousels go beyond it.
   - `{type: Link}` attachments are not mistaken for media.
 - **Deleted posts** answer 410 with a `Tombstone`. Actor `published` is truncated to the day. The `webfinger` property
-  (FEP-2c59) is on every actor.
+  (FEP-2c59) is on every actor, and a peer's is read: a handle on another domain than the actor's host is shown once
+  that domain's WebFinger confirms it (2026-10-06).
 - **Live check:** the whole follow, post, reply, like, boost, DM, edit and delete set round-trips with GoToSocial
   0.22.1 (`tools/pasture/`).