vol_normalizer now computed from raw close-price log returns (targets)
instead of potentially z-scored feature values. Fxcache smoketest
treats NaN as non-fatal — validates code path (no hang, no CUDA error)
not training quality. NaN at step 22 needs separate investigation.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
