A sender's digest of its followers here is compared and mended

FEP-8fcf, received. When a delivery's Collection-Synchronization header digests the sender's followers on PrivaPub
otherwise than the personas following it, a job reads the list the header names (on the sender's origin, signed by the
instance actor): a follow the list leaves out ends, only when the list is the one the digest describes; a request it
lists is taken as accepted; a persona it lists that follows nothing there sends Undo{Follow}, as Mastodon does. Each
claiming delivery is compared once.

Checked live (scenarios/followsync.sh, now 15 checks): PrivaPub ends a follow Mastodon lost and undoes one only
Mastodon remembered.

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

CLAUDE.md

@@ -562,10 +562,12 @@ tools/pasture/run.sh down                                            # removes e
 - **Threads (`scenarios/threads.sh`, needs mastodon):** mastouser follows alice, carol answers alice's public post,
   and opening the thread on Mastodon finds carol's reply through alice's `replies` (the scenario makes Mastodon's copy
   look ten minutes old: Mastodon reads a thread's replies only five minutes after it first holds the post). 5 checks.
-- **Followers synchronisation (`scenarios/followsync.sh`, needs mastodon):** PrivaPub forgets mastouser's follow of
-  alice (mongo), alice's followers-only post naming mastouser makes Mastodon read her roll-call and drop it; then
+- **Followers synchronisation (`scenarios/followsync.sh`, needs mastodon):** sent: PrivaPub forgets mastouser's follow
+  of alice (mongo), alice's followers-only post naming mastouser makes Mastodon read her roll-call and drop it; then
   Mastodon forgets a follow (rails) and alice's next followers-only post makes it send the `Undo` PrivaPub applies.
-  Follows are checked in Mastodon's database: its API caches relationships for a day. 8 checks.
+  Received: alice and bob follow mastouser; Mastodon forgets alice's follow and mastouser's followers-only post makes
+  PrivaPub end it, then PrivaPub forgets it and the next makes PrivaPub undo it there. Follows are checked in Mastodon's
+  database: its API caches relationships for a day. 15 checks.
 - **Pins (`scenarios/pins.sh`, needs mastodon):** a Mastodon account pins and unpins while alice follows it, alice pins
   and unpins while it follows her, a fresh account's earlier pin shows once PrivaPub resolves it, and following it brings
   its earlier posts (its outbox). 9 checks.