forked from 1b-agent/fieldcraft-upstream
arc-shallow-arch: a sinusoidal arch of 40 × 2 × 1 hex20 under a sinusoidal dead load scaled to the one-mode closed form's upper limit load: the upper limit point at 0.992 (−0.8 %), the lower at 0.219 (0.8 % of the peak load) and exactly one negative eigenvalue between them. ROADMAP and parity updated, docs/oracle.md regenerated. Co-Authored-By: Claude Opus 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo