Several people edit one model at once through a server you run yourself
(archify-vscode-ext-sync); the files stay ordinary files on each disk.
Sign-in through the browser, offline-first with later merge, teammates'
cursors in the Source view and text editors, and a Shared section on the
model page with people, versions, Compare and Restore.
Without a server nothing changes: the sync code is a separate bundle that
loads only when a model is shared, after a sign-in, or when a sync command
or invite link is used.
