Use this when you are handed an STL, OBJ or 3MF of a mostly prismatic mechanical part (plate, bracket, spacer, flange, housing block) and need an EDITABLE kernelCAD model of it rather than a faceted lib.fromSTL import. Deterministic, measured, self-verifying: it welds and checks the mesh, segments planes and cylinders, picks the extrusion axis, slices each band and fits exact lines / arcs / circles, snaps near-round values (each snap recorded), then emits a readable .kcad.ts with named param()s — a revolve for concentric round stacks, extruded profiles otherwise, .hole()/.holes() for through, blind and counterbored bores (axial and side-drilled), .cutout() for pockets, .fillet() for constant-radius edge blends (radius measured on the sharp edge, edges grouped by radius and picked with the shortest exact edge query), boolean subtractions for what no drilling feature can reach. It then EVALUATES that script and compares it with the mesh: volume IoU (column ray casting) and symmetric surface deviation (max + RMS), over up to 4 refinement passes. Returns { script, ledger, fidelity: { maxDeviationMm, rmsMm, volumeIoU, verdict: faithful | approximate | failed, thresholds }, unmatchedRegions, features, passes }. A fillet or sharp reading is kept by which measures better; variable-radius blends and chamfers are reported, not forced. The verdict is computed from the numbers — faithful needs IoU >= minIoU AND max deviation <= maxDeviationMm AND a watertight mesh AND no unmatched region. Freeform surfaces, tilted planes and side bosses are listed in unmatchedRegions (reference.mesh.freeform-region-unmatched), never silently dropped. The ledger uses fact ids equal to param names, so resolve_assumptions on the written .ledger.json yields paramOverrides for set_param. Pass { out } to write the script and ledger; the mesh itself is never modified.
