Seed-2 shell carver measured: vertical-shafts route-edge-0, the layer's own connection edge from the 2-3 lower
mouth. Connection edges legitimately run beside the passage 12-20 m from the mouth, so an 8 m mouth-sphere exclusion
rejects 9/16 otherwise valid plans. Points to one continuous tube across the mouth instead of two overlapping ones.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1
