Arrival edge floor aligned to the passage mouth, 0.75 m backbone floor-support budget, anchors on the planned floor: 0 unsupported, 0 grade failures. Open: 196/50,967 capsule samples blocked where a higher descending edge's floor backing meets the next edge (route-edge-6/7). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1