A world whose shape comes from who invites whom. Your tab will host it for 2 hours. Everyone who comes in, you included, holds exactly two invitations, and nobody ever gets more.
Whoever opens the world is its authority: their tab signs every invitation and enforces the rules.
Talk here about who deserves an invitation.
What you keep: your part of the tree, not the whole of it. Nobody keeps the whole tree.
It's on this browser's shelf, signed by the world. Open your shelf.