Feature vectors are [f64; 51] after WAVE 10 (Proxy OFI removal): [0..5] static, [5..15] known, [15..51] unknown (36 features) Old code used fv[15..54].min(fv.len()) which silently produced 36 features per step but expected 39 in Array2 shape → ShapeError. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>