A space is one access list plus every object under it, replicated on every member's devices with no master copy.

Every later guarantee about sharing and offline work rests on this shape.

The unit of sharing is a space. Think of a room. By the door hangs a guest list.

Inside are objects. Pages, chats, types. Every object in the room is shared with everyone on the list.

The room has a header. Signed once, at creation. The space id is made from it, and it can never change.

The guest list is a chain of signed slips. Who was invited. Who joined. Who was removed.

A space lives on every device of every member. There is no master copy. The guest list and the objects are all there is.

Check yourself. Where does a space live?