dqn_distributional_q.cu:285 atomicAdds ce/B into ss_q_loss (kernel-side
B divide, matching ppo_clipped_surrogate.cu:269-271's b_inv pattern).
Host previously divided by B AGAIN at integrated.rs:3944 and :5196 —
true mean CE (≈ 3.0 for 21-atom softmax) appeared as 3.0/1024 ≈ 0.003.
The "baseline l_q=1.45 at step 500" was actually a missing-zero-out
artifact: ss_q_loss accumulated 500 × 0.003 = 1.46 across steps before
bf8887400 fixed the zero-out, exposing the underlying double-divide.
Q learning has been working correctly the whole time — only the
diagnostic display was wrong.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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