The continuity core (kernel bridge: Hermite control rows reproducing a support surface's position, tangent, curvature and change of curvature, G0 to G3), surface.blend between two edge chains (#764), and a crown for fitted patches. Existing patches and fillets are unchanged by default (crown 0 is the plain patch bit for bit). SurfaceBlend and Patch.crown are noted under format 22.
Part of #771 and #772. solid.sweep and surface.sweep take orientation (perpendicular, parallel or a direction), twist (up to 4 turns) and end scale (0.01 to 100), applied about the profile's normal through the path's start; default options run the old sweep, so existing sweeps are unchanged. New fields are optional, left out when unset and noted under format 21; twist and scale are model parameters. Both sweep dialogs get Orientation, Twist and End Scale rows; labels in every catalog. Checked on main + this branch: cargo check --workspace, kernel/engine/UI sweep tests, the doc suite and the robustness goldens.
Extend works on any surface: natural (continuing the face's own surface), tangent (G1 run-off) or curvature (G2 run-off), by a distance, up to a plane or face, or back to the surface's bounds, with neighbouring edges lengthened to meet. Untrim and Extend share face parameter-loop helpers. The new SurfaceExtend fields are noted under format 21. Closes#760.
Ruled Surface: strips off an edge chain in normal, tangent, angle or direction mode, exact planes/cylinders/cones where possible, mitred or round corners, stitched into one surface body. SurfaceRuled is noted under format 21. Closes#762.
Adds sheet.perforate: round holes on a staggered or square grid over the flat sheet, kept clear of edges, cut-outs and bend zones. The holes go to the flat pattern, the DXF and the measured volume rather than the B-rep, so a panel can carry many thousands of them.
Thin Extrude builds walls of a set thickness along sketch curves, open chains and closed loops, with the wall centred, inside, outside or on both sides at two thicknesses. Saved under format 20 (thin on an Extrude); an extrude without thin saves as before. Closes#721.
inputs_mut, inputs and expressions are now built on one exhaustive walk (walk_exprs / walk_exprs_mut) instead of two hand-written matches over FeatureKind. inputs() no longer clones the feature, plane chains are walked with the same nesting cap for inputs as for expressions, and a new variant without a walk arm does not compile. A golden record of every variant's expressions guards the walk.
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