Abracadabra

The server this site cannot exist without: Rust, Tokio, Axum, and Yrs holding every document. It speaks one binary protocol over one WebSocket, and it does four jobs — persist, broadcast, enforce permissions, and route RPC.

The job that is easy to miss

Permissions. Visitors here can edit pages but cannot sign the guestbook as somebody else, and that is not a UI restriction — the write is refused at the server against a signed identity. "Can write" was never a scope worth granting; the guestbook is its own document with its own grant, which is the narrowest thing that could possibly work.