- parse Excel input by header strings (pier, IP, bearing tables) - DMS azimuth parser (E03), input validation (E01, E02) - pure geometry: axis, bearings, stepped coping, column, footing, piles, blinding - warnings W01, W02, W05, W07, I01 - regression tests against spec.md section 12 (P1) Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>