When the grid layout does not fit a swept body (sides at an angle to the axes, root arcs where
an arm meets its bosses), mesh.plan tries the ring-and-pillow layout (cmd/plan/pillow.rs): each
boss is an annulus from its bore or pedal hole to its circle through every level, the arm a grid
carved a margin inside the outline and the bosses, with a pillow layer of blocks to the wall each
boundary face faces; a grid corner facing a boss and the outline gets a corner block reaching the
kink where the outline leaves the boss's circle. The old crank test (frame cuts) becomes the
heavy acceptance test at sizes 2.5, 3 and 4; the moved frame cut keeps a unit test.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo
