# STEP import

SolveCraft reads STEP (ISO 10303-21; AP203, AP214 and AP242 geometry) with its own reader in `crates/kernel/src/step_in` (written from the public standards; no third-party STEP code). A STEP file becomes an **Import** base feature on the timeline: it holds the file's B-rep (the STEP text is kept in the design, so the design reopens without the file) and later features — fillets, holes, cuts sketched on its faces, shells — build on its bodies.

- **Open**: File → Open (`doc.open`) accepts `.step`/`.stp` in any case and starts a new design; `solvecraft part.step`; `solvecraft-cli eval part.step`, `solvecraft-cli run script.json --in part.step`; the MCP `open` tool.
- **Insert** into the current design: File → Insert STEP… or SOLID → INSERT (`FusionImportCommandFromToolbar {path}`).
- **Drag and drop** a STEP file on the window: inserted when the design has features, opened otherwise.

Read: manifold solid breps (with voids), faceted breps, shell-based surface models; planes, cylinders, cones, spheres, tori, B-spline and rational B-spline surfaces (with knots, Bézier, uniform, quasi-uniform), surfaces of revolution and linear extrusion, trimmed surfaces; lines, circles, ellipses, B-spline curves, polylines, trimmed/surface/seam curves; length and angle units (SI prefixes, conversion-based units such as inches); product names (body names come from the solid's name, else the product's); surface colours; assemblies (next-assembly-usage occurrences placed by item-defined transformations, and mapped items) — the product tree is kept in the feature for the components milestone. Files are untrusted: sizes, entity counts and nesting are capped and every kernel call is guarded. What cannot be read becomes a warning on the feature (a face left out gives an open body); not read yet: offset surfaces, pcurve-only edges.

## Fusion corpus

Generated by `cargo xtask step-corpus`. Each case is a part exported from Fusion as STEP (AP214; kept locally in `plan/fusion/oracle/`, never committed). SolveCraft opens `part.step` exactly as File → Open does (an Import base feature) and compares with Fusion's own measurements: body count, volume and area (relative tolerance 1e-3) and the number of faces read from the file.

**60 / 66 files pass.**

| Case | Result | Bodies | Volume mm³ (got / Fusion) | Area mm² (got / Fusion) | Faces (got / Fusion) | ms | Notes |
|---|---|---|---|---|---|---|---|
| 01-box | pass | Box | 24000.000 / 24000.000 | 5200.000 / 5200.000 | 6 / 6 | 16 |  |
| 02-cylinder | pass | Cylinder | 35339.346 / 35342.917 | 6125.844 / 6126.106 | 3 / 3 | 37 |  |
| 03-box-through-hole | pass | Box | 45738.489 / 45738.053 | 9327.795 / 9327.788 | 7 / 7 | 28 |  |
| 04-revolve-vase | pass | Vase | 112487.028 / 112499.479 | 13156.053 / 13156.615 | 5 / 5 | 371 |  |
| 05-taper-extrude | pass | Frustum | 61814.826 / 61814.826 | 9676.915 / 9676.915 | 6 / 6 | 19 |  |
| 06-symmetric-extrude | pass | Block | 30000.000 / 30000.000 | 6200.000 / 6200.000 | 6 / 6 | 1 |  |
| 07-fillet-all-edges | pass | Box | 23340.395 / 23340.849 | 4726.168 / 4726.265 | 26 / 26 | 63 |  |
| 08-chamfer | pass | Box | 23730.667 / 23730.667 | 5029.352 / 5029.352 | 10 / 10 | 12 |  |
| 09-shell | pass | Box | 13632.000 / 13632.000 | 13992.000 / 13992.000 | 11 / 11 | 8 |  |
| 10-rect-pattern-holes | pass | Plate | 29803.869 / 29803.540 | 14652.467 / 14652.389 | 18 / 18 | 270 |  |
| 11-circular-pattern-flange | pass | Flange | 66758.484 / 66758.844 | 19320.589 / 19320.795 | 10 / 10 | 90 |  |
| 12-mirror-feature | pass | Base | 21392.261 / 21392.920 | 6530.917 / 6530.973 | 10 / 10 | 16 |  |
| 13-combine-join | pass | A | 45547.074 / 45571.680 | 8633.463 / 8634.336 | 9 / 9 | 19 |  |
| 14-combine-cut | pass | A | 42934.679 / 42931.417 | 9706.604 / 9706.858 | 7 / 7 | 95 |  |
| 15-combine-intersect | pass | A | 54442.787 / 54454.273 | 7381.985 / 7382.743 | 7 / 7 | 223 |  |
| 16-sweep | pass | Tube | 2584.167 / 2584.724 | 1779.580 / 1779.698 | 5 / 5 | 430 |  |
| 17-loft | pass | Loft | 35124.785 / 35125.498 | 6496.433 / 6495.000 | 6 / 6 | 91 |  |
| 18-hole-features | pass | Plate | 33890.986 / 33890.710 | 8568.685 / 8568.696 | 13 / 13 | 26 |  |
| 19-l-bracket-constrained | pass | LBracket | 14720.000 / 14720.000 | 5472.000 / 5472.000 | 8 / 8 | 9 |  |
| 20-slot-constrained | pass | Slot | 2965.374 / 2965.487 | 1774.635 / 1774.690 | 6 / 6 | 4 |  |
| 21-draft | pass | Box | 54574.737 / 54574.737 | 8781.998 / 8781.998 | 6 / 6 | 1 |  |
| 22-split-body | pass | Cyl, Cyl (1) | 75380.935 / 75398.224 | 12954.433 / 12955.175 | 6 / 6 | 19 |  |
| 23-bracket-multifeature | pass | Bracket | 59331.560 / 59331.129 | 18290.761 / 18290.737 | 19 / 19 | 37 |  |
| 24-user-parameters | pass | Block | 34822.124 / 34821.903 | 8114.167 / 8114.159 | 7 / 7 | 4 |  |
| 25-sketch-triangle | pass | Triangle | 4032.155 / 4032.155 | 2274.099 / 2274.099 | 5 / 5 | 18 |  |
| 26-sketch-belt | pass | Belt | 11326.051 / 11326.170 | 5637.346 / 5637.404 | 7 / 7 | 24 |  |
| 27-sketch-trapezoid | pass | Trapezoid | 5342.311 / 5342.257 | 3066.959 / 3066.946 | 8 / 8 | 9 |  |
| 28-blind-pocket-fillets | pass | Block | 84299.400 / 84299.249 | 16279.542 / 16279.572 | 23 / 23 | 56 |  |
| 29-two-sided-and-partial-revolve | pass | Block | 25731.359 / 25731.307 | 6312.589 / 6312.602 | 12 / 12 | 9 |  |
| 30-fillet-after-shell | pass | Box | 21745.919 / 21745.876 | 14968.279 / 14968.332 | 27 / 27 | 82 |  |
| 31-fillet-l-all-edges | pass | L | 14321.347 / 14321.626 | 5023.960 / 5024.045 | 38 / 38 | 68 |  |
| 32-boss-plate-fillets | pass | Part | 33590.191 / 33590.350 | 9929.841 / 9929.864 | 10 / 10 | 620 |  |
| 33-fillet-tangent-chain | pass | Slot | 8236.938 / 8237.122 | 2793.516 / 2793.569 | 14 / 14 | 202 |  |
| 34-chamfer-then-fillet | pass | Box | 22892.369 / 22892.421 | 4753.674 / 4753.688 | 18 / 18 | 31 |  |
| 35-fillet-curved-curved | FAIL | Tee | 63090.315 / 63171.443 | 10267.244 / 10269.348 | 6 / 6 | 1602 |  |
| 36-corner-blend-two-radii | pass | Box | 57799.345 / 57800.240 | 8585.404 / 8585.524 | 18 / 18 | 88 |  |
| 37-pyramid-apex-blend | FAIL | Pyramid | 15483.389 / 15465.575 | 3972.101 / 3914.581 | 18 / 18 | 786 |  |
| 38-coincident-cylinders | pass | A | 15706.106 / 15707.963 | 3769.742 / 3769.911 | 3 / 3 | 27 |  |
| 39-tee-pipe | FAIL | Tee | 24069.177 / 24096.237 | 16706.241 / 16710.048 | 7 / 7 | 64 |  |
| 40-box-sphere-torus | pass | A | 36287.351 / 36287.433 | 10695.939 / 10696.165 | 10 / 10 | 764 |  |
| 41-tube-radial-holes | FAIL | Tube | 20070.139 / 20243.981 | 14849.742 / 14873.773 | 22 / 22 | 428 |  |
| 42-overlapping-patterns | pass | Plate | 38489.045 / 38487.064 | 21687.203 / 21686.603 | 43 / 43 | 469 | solid 'Plate': imported as an open body (the shell is not closed) |
| 43-cut-splits-body | pass | Bar, Bar (1) | 28000.000 / 28000.000 | 7200.000 / 7200.000 | 12 / 12 | 19 |  |
| 44-shell-l-bracket | pass | L | 8384.000 / 8384.000 | 8784.000 / 8784.000 | 15 / 15 | 17 |  |
| 45-shell-boss-plate | pass | Part | 13676.925 / 13676.602 | 14156.500 / 14156.602 | 15 / 15 | 11 |  |
| 46-shell-two-open-faces | pass | Box | 16044.000 / 16044.000 | 11398.000 / 11398.000 | 10 / 10 | 2 |  |
| 47-draft-curved-pocket | pass | Block | 111388.144 / 111387.712 | 17700.329 / 17700.361 | 11 / 11 | 11 |  |
| 48-pulley | pass | Pulley | 168507.117 / 168510.841 | 23718.181 / 23718.644 | 12 / 12 | 83 |  |
| 49-helical-sweep | pass | Spring | 4736.230 / 4738.099 | 4766.821 / 4767.652 | 3 / 3 | 390482 | solid 'Spring': face wrapping around a closed surface kept whole: split line does not reach the rings |
| 50-sweep-tight-bend | FAIL | Bend | 3822.321 / 3758.443 | 1708.995 / 2153.937 | 5 / 5 | 1797 |  |
| 51-loft-rect-circle-offset | pass | Loft | 61143.729 / 61133.116 | 9415.804 / 9411.655 | 6 / 6 | 142 |  |
| 52-circular-pattern-fillet | pass | Hub | 47206.223 / 47206.850 | 14142.022 / 14142.171 | 21 / 21 | 625 |  |
| 53-path-pattern | pass | Plate | 35010.589 / 35010.398 | 16463.939 / 16463.894 | 13 / 13 | 87 |  |
| 54-mirror-body-fillets | pass | Bracket | 22780.205 / 22780.089 | 6972.823 / 6972.832 | 12 / 12 | 38 |  |
| 55-tapped-hole-cosmetic | pass | Plate | 17542.404 / 17542.314 | 4761.584 / 4761.596 | 8 / 8 | 13 |  |
| 56-holes-on-curved-face | FAIL | Cyl | 77733.175 / 77942.388 | 10590.123 / 10593.139 | 7 / 7 | 93 |  |
| 57-hole-pattern-sketch-points | pass | Plate | 36767.098 / 36766.712 | 11818.159 / 11818.153 | 24 / 24 | 165 |  |
| 58-phone-stand | pass | Stand | 74559.445 / 74559.177 | 29148.741 / 29148.785 | 19 / 19 | 25 |  |
| 59-enclosure-base | pass | Enclosure | 34309.026 / 34309.486 | 33795.404 / 33795.610 | 39 / 39 | 74 |  |
| 60-pipe-flange | pass | Flange | 323660.116 / 323660.979 | 56984.492 / 56984.564 | 16 / 16 | 495 |  |
| 61-shaft-keyway | pass | Shaft | 47493.351 / 47525.946 | 9675.779 / 9677.096 | 14 / 14 | 77 |  |
| 62-heat-sink | pass | HeatSink | 43125.000 / 43125.000 | 45725.000 / 45725.000 | 66 / 66 | 41 |  |
| 63-hinge-knuckle | pass | Hinge | 4781.312 / 4783.117 | 4109.841 / 4110.287 | 14 / 14 | 47 |  |
| 64-sketch-tangent-arc-chain | pass | Wave | 4800.000 / 4800.000 | 3843.701 / 3843.712 | 9 / 9 | 47 |  |
| 65-sketch-gear-tooth | pass | Tooth | 3987.829 / 3988.084 | 1945.416 / 1945.485 | 9 / 9 | 20 |  |
| 66-sketch-linkage | pass | Link | 8045.431 / 8045.386 | 4308.168 / 4308.175 | 10 / 10 | 94 |  |