Mount an adapter directory under id. Validates layer-name and
rank/shape compatibility against the base BEFORE any weights are
attached — a bad adapter fails here, never at request time
(reference: resolver.py + mount.py add_adapter checks).
Resolve a request's adapter spec to validated ids ([] for none). Unknown ids are an error — selection must fail loudly, not no-op.
Remove id from every linear (frees its arrays). The mount points
stay in place for other adapters, like the reference.
Ordered, content-addressed namespace for the actual mounted composition.