A Merkle-CHAMP maps random 32-byte labels to sealed blobs; every chunk and large folder is spread across labels the server cannot relate; the folder shape lives inside the ciphertext; each bag hangs from one root hash.

It is the shape the server actually sees, and it has no shape.

So what does a server hold for you? A map from random thirty two byte labels to sealed blobs.

The map is a Merkle champ. A hash tree that works like a dictionary. Change one entry, and only the path to the root changes.

Every five mebibyte piece of a file sits under a different label. A big folder is spread the same way.

Your folders have a shape. The bag has none. The shape lives inside the ciphertext, where the server cannot see it.

A bag has one root hash. Everything in it hangs from that one hash.

Check yourself. How many labels does a 20 MiB file occupy, and can the server relate them?