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
Owner decision of 2026-10-06 (FEP-8fcf). A persona's delivery addressed to its followers carries a signed
Collection-Synchronization header naming its followers, its roll-call (…/groupies/roll-call) and the digest of its
accepted followers on the receiving server only. The roll-call answers a signed request with the persona's followers
on the signer's server and nobody else's.
Mastodon gives every Undo{Follow} it sends after reading a roll-call the same id (…#follows//undo), so a second one
looked like a copy: an Undo of a Follow that comes again while the follow it ends exists again is now kept once per
follow.
Checked live (scenarios/followsync.sh): Mastodon drops a follow PrivaPub lost, and undoes one it lost itself.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw
thepraandClaude Opus 5.5