Binary format: magic + version + step + sections. Sections include ISV (585 f32), 26 device buffers (DQN/policy/value/IQN/FRD/NoisyNet/ outcome weights + targets), 20 AdamW optimizer states, and encoder (delegated to CfcTrunk). All device transfers use mapped-pinned DtoD. load_checkpoint invalidates CUDA graphs to force re-capture. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>