State dicts produced by Module.state_dict() carry a hidden _metadata attribute storing version information per submodule. That attribute is detected, packed alongside obj in the container, and reattached on load.

Every tensor comes back with exactly the values it held. Tensors saved together that share a storage — a tensor and its views, or overlapping views — are written once and share it again after load; a tensor that shares with nothing else saved is written dense, so a view saved alone does not carry the rest of its base. On Metal only the views taken through Lucid's view ops are known to share; two tensors that merely read the same buffer are saved apart.