2-state read receipts (sent / read) via two custom packets:
MarkConsoleRead (client->server, header 4085) sent on thread focus,
relayed by the emulator to the peer as ConsoleReadReceipt (server->
client, header 4086). Client marks own messages READ and renders
checkmarks. Live-relay only (no DB table / login batch) since the
client doesn't persist message history across sessions.
Store messages to offline friends in messenger_offline (capped inbox),
replay on login via the existing FriendChatMessageComposer with an
"offline" extraData marker, and render a "sent while offline" tag in
the client thread. No new packets; emulator + small client touch.
Bite-sized TDD plan across all three codebases for the friend-groups
feature: 4 client->server category packets (renderer composers +
Arcturus handlers), DB persistence (reusing existing
messenger_categories + messenger_friendships.category), server-
authoritative re-push via existing MessengerInit/UpdateFriend
composers, and client store actions + chip-filter UI + manager modal +
per-friend assign control + pure filter helper with tests.
simoleo89