FEDERATION.md and CLAUDE.md describe media, blocks, pins and reports

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012CzABvBkbcFqoHdmi8b9WB

FEDERATION.md

@@ -67,9 +67,16 @@ Received:
 | `Like` | counted and notified, on posts the liker could see |
 | `Announce` | counted and notified for local posts; shown to followers of the announcer, with the original refetched from its origin |
 | `Delete` | deletes the object, or the actor and its follows |
+| `Flag` | becomes a report for this server's moderators |
 
 Sent: `Follow`, `Undo{Follow}`, `Create{Note}`, `Update{Note}`, `Update{Person}`, `Delete{Tombstone}`, `Accept{Follow}`,
-`Announce` (communities). A deleted post answers 410 with a `Tombstone`.
+`Reject{Follow}`, `Like`, `Announce` and their `Undo`, `Flag`. A deleted post answers 410 with a `Tombstone`.
+
+- **Attachments** are `Document`s with `mediaType`, `name` (alt text), `blurhash`, `focalPoint`, `width` and `height`.
+  Uploaded files have all metadata removed.
+- **Pinned posts** are the actor's `featured` collection (`/trophies`); `featuredTags` is `/tattoos`.
+- **Blocks are never sent.** A blocked account is sent `Reject{Follow}` if it followed, and is unfollowed.
+- **Reports** are sent as `Flag` by the instance actor, never by the reporting account.
 
 A `Create`'s `Note` carries Mastodon's `content`, `contentMap`, `summary` and `sensitive`, plus `Mention` and `Hashtag`
 tags. A post's title becomes `name` and is also the first, bold line of `content`, because Mastodon does not show
@@ -94,7 +101,7 @@ followers-only posts are recognised by the author's own `followers` collection.
 
 ## Known limitations
 
-- Avatars cannot send likes or boosts yet (that arrives with the Mastodon client API), and media uploads and polls are not
-  implemented.
+- Polls and custom emoji are not implemented.
+- Remote media is fetched through this server's proxy when a local client displays it.
 - Collections expose counts, not members.
 - Only `rsa-sha256`-style keys are verified. RFC 9421 signatures are planned.