The GPU backtest evaluator computed state_dim = feature_dim + 3 = 53
(unaligned), but the model was trained with 56 (8-aligned for H100
tensor cores). This caused matmul shape mismatch [5,53] vs [56,512]
and forced CPU fallback on every walk-forward evaluation.
Fix: align state_dim at construction with (dim + 7) & !7, matching
the training pipeline. The CUDA gather_states kernel already zero-pads
extra positions, so no kernel changes needed.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
cbf81d293d