Added entropy gradient (∂H/∂logits) to PPO backward, fires on ALL
batch elements. Fixed controller: COEF_FLOOR=0.01, COEF_MAX=0.5,
emergency bypass Wiener when entropy < 50% target. Symmetric response
(non-zero coef even when entropy above target).
Still collapses: PPO done-gated gradient concentrates on trading
actions, overwhelming the diffuse entropy gradient. Hold drops to 0%
despite coef=0.5. The surfer philosophy needs structural enforcement
at the action-selection level, not just gradient-level entropy bonus.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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