Function diff 

pub fn diff(local: &Manifest, remote: &Manifest) -> Delta

What changed between the tree as it is (local) and as the last sync left it (remote).

Identity is category-scoped: a path that was a file and is now a symlink is uploaded and not deleted, since the upload overwrites the name in place, which is the daemon’s own extraction contract. MANIFEST_NAME never appears in either set.