Module feature 

Chamfer and fillet on a straight vertical edge of an exact prism (#68).

The contract

An edge is selected by the CORNER it belongs to, not by an opaque index: a caller naming “the corner nearest this point” survives a topology change that renumbers edges, while an index does not.

What is exact here

Chamfering a vertical edge of a prism replaces one corner of its profile with a straight cut, so the result is a prism over a polygon with one more vertex. That is exactly the shape extrude_polygon_rings already builds – no new surface families, no approximation.

A constant-radius FILLET replaces the corner with a circular arc, so the wall becomes a cylindrical face. That is representable, but stitching a cylindrical wall into the prism assembly is not the same construction, so it is refused here rather than approximated by a polyline. Refusing is the honest answer: a caller asking for a fillet and receiving a many-segment chamfer would have no way to tell.

Refusals

Variable radius, edge loops, curved edges, and fillets all return typed refusals naming the missing capability, never a silent no-op. A no-op is the worst outcome: the caller believes the feature was applied.

Structs

BlendCorner

Corner geometry of the fillet: where the blend starts, ends, and centres.

Enums

EdgeSelector

Which edge a feature applies to.

FeatureSize

How much material a feature removes.

Functions

chamfer_extruded_profile

Chamfer one vertical edge of an exact extruded rectangle.

chamfer_polygon_corners

Chamfer several corners of an arbitrary polygon profile.

fillet_extruded_profile

Fillet one vertical edge of an exact extruded rectangle.

fillet_polygon_corner

Fillet one corner of an arbitrary closed polygon profile.

fillet_polygon_corners

Fillet several corners of a polygon profile in one solid.