The warp-parallel (32,1,1) change to c51_loss_reduce caused the same
hang as isv_feature_gate: changing block_dim inside graph_mega alters
CUDA Graph node structure on Hopper's TMA scheduler. Must stay (1,1,1).
Also: batch_size 8192→16384, gpu_n_episodes 1024→4096, num_atoms 51→52
to align h100.toml with dqn-production.toml.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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