Hard-surface Tier 3: a mechanical reference is planes and cylinders wearing noise, and the tool now knows which is which.
- Detection. The reference segments into smooth regions walled by sharp edges; each region is fitted as a plane, a cylinder (exact axis and radius), or honestly "free". A box is six planes and nothing else; a sphere refuses to pretend.
- From Primitives. Every detected cylinder proposes mathematically exact rings — round by construction, axis-perpendicular, spaced by your target edge — as ghosts in the usual accept/discard lane. Traced rings wobble with the mesh; these come from the fitted ideal.
- Flatten (V over a patch). The patch interior is projected onto its boundary's best-fit plane while the rim stays welded — a scanned flat panel comes out actually flat (0.022 of noise measured down to 1e-10). Mirrored pairs flatten as one.
The full hard-surface routine: From Creases → Accept → From Primitives → Accept → Suggest Arcs → Accept → Support Loops on the key edges → V on the flats → Apply.
Suite: 496 headless + 19 GUI checks, 117-layout sweep clean.