An AtCollection<T> is a fully-qualified namespace ('todos.demos', 'nodes.dockerstats.demos', etc.) plus the verbs that read and write CItem<T> records under it.
A CItem<T> is one typed record, carrying (owner, id, obj, sharedWith, type, createdAt, expiresAt, availableAt, readBy).
Sub-collections let any CItem host its own AtCollection<U> of children, with the sub's namespace composed from the parent's id and namespace. To arbitrary depth.
That's the entire object graph.