kernelcad

Add Surface

add_surface

Use this when you need an organic, freeform, or swept shape — a body shell, panel, fairing, ergonomic curve, lens, or sculpted form — authored as a NURBS Surface into the user's .kcad.ts, OR when you need to finish surfaces into a watertight solid or taper faces for moldability. One authoring/finishing path, selected by kind:

'nurbs' — insert a nurbsSurface(...) / surfaceFromCurves(...) call. Pass either { controls, degree, weights?, knots?, periodic? } for direct construction, OR { section_sketch_ids } for skinning. Weights are honored: supply rational weights to build exact circles/cylinders/spheres/conics (the surface becomes rational); omit weights for a non-rational surface.
'boundary' — insert a surfaceFromBoundary([c1,c2,c3,c4], opts?) call: one NURBS face through 4 boundary Curve3D refs (bottom, right, top, left in loop order; adjacent endpoints must coincide within 1e-6 mm).
'trim' — insert a <surface>.trimTo(<by>) or <surface>.split(<by>) call. Pass surface_binding (the Surface variable name), by_binding (the cutter Surface variable name; Shape/Curve3D cutters are deferred to a later slice), and op: 'trim' (keep the largest imprinted piece) or op: 'split' (return both halves as a [Surface, Surface] tuple).
'sew' — insert a sew([s0, s1, ...], opts?) call to stitch N surfaces into a closed watertight solid. Pass surface_bindings (array of Surface variable names). Use after trim/boundary to close patches into a solid: trim → sew → solid pipeline. Optional tolerance (mm, default 1e-6) and require_closed (emits feature.surface-sew.open-shell if result is not watertight).
'draft' — insert a <shape>.draft(angleDeg, { face, neutralPlane?, pullDir? }) call to taper the selected face(s) for mold release. Pass shape_binding, angle_deg (0–90), and face (canonical name, label, or FaceQuery descriptor). Lowering emits feature.draft.failed on invalid geometry. The returned Surface produces no Shape until you chain .thicken(t) or .toShape() (do that via add_feature on the binding name). Returns the modified code + diagnostics. Each kind fails closed on its own missing required params.

Input Schema

TableJSON Schema

Name	Required	Description
`op`	No	kind:'trim' — 'trim' discards the smaller half (calls .trimTo()); 'split' retains both halves (calls .split()).
`code`	Yes	Current .kcad.ts source.
`face`	No	kind:'draft' — face selector for the face(s) to taper. Accepts a canonical name (top/bottom/front/back/left/right), a user label declared via faceLabels, or a FaceQuery descriptor string.
`kind`	Yes	Which surface-construction or surface-finishing path to use: 'nurbs' \| 'boundary' \| 'trim' \| 'sew' \| 'draft'.
`knots`	No	kind:'nurbs' — optional explicit knot vectors; missing => clamped uniform inferred.
`degree`	No	kind:'nurbs' — degrees in U and V; each in [1, nU-1] / [1, nV-1].
`weights`	No	kind:'nurbs' — optional rational weights, same grid shape as controls. Ignored in slice-1.
`controls`	No	kind:'nurbs' — control-point grid for direct construction (controls[u][v] = [x, y, z], mm).
`periodic`	No	kind:'nurbs' — optional periodic flags per parametric direction.
`pull_dir`	No	kind:'draft' — demoulding direction as [x, y, z]. Defaults to the face normal at lower time.
`sampling`	No	kind:'boundary' — points sampled along each boundary (default 15).
`angle_deg`	No	kind:'draft' — draft angle in degrees [0, 90]. The face is tapered outward by this angle relative to the pull direction.
`tolerance`	No	kind:'sew' — edge-merging tolerance in mm (default 1e-6). Edges within this distance are merged.
`by_binding`	No	kind:'trim' — JS variable name of the cutter Surface (must be declared in source). Shape/Curve3D cutters are deferred.
`continuity`	No	kind:'boundary' — continuity grade applied to every edge ('C0' \| 'C1' \| 'C2'), or an array of 4 grades (one per edge, bottom/right/top/left order). Default 'C0'.
`binding_name`	No	JS const name for the new binding (kind:'nurbs' default surface_<N>; kind:'boundary' default _surface_<N>; kind:'trim' default _trimmed_<N>; kind:'sew' default _sewn_<N>; kind:'draft' default _drafted_<N>).
`neutral_plane`	No	kind:'draft' — parting-line face (the plane where drafted faces remain fixed). Defaults to `face` if omitted.
`shape_binding`	No	kind:'draft' — JS variable name of the Shape to taper (must be declared in source).
`curve_bindings`	No	kind:'boundary' — tuple of 4 existing Curve3D variable names (bottom, right, top, left) declared earlier in the source.
`require_closed`	No	kind:'sew' — when true the lowerer emits feature.surface-sew.open-shell if the stitched result is not a watertight solid.
`surface_binding`	No	kind:'trim' — JS variable name of the Surface to trim/split (must be declared in source).
`surface_bindings`	No	kind:'sew' — JS variable names of the surfaces to stitch into a solid (each must be declared in source).
`section_sketch_ids`	No	kind:'nurbs' — existing sketch FeatureIds (2 or more) to skin a surface through, in order.

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 11, 2026

removedOutput schema / properties

Removed value: -{
-  "binding_name": {
-    "description": "JS const name bound to the new construct (when one was created).",
-    "type": "string"
-  },
-  "diagnostics": {
-    "description": "Diagnostics from re-evaluating the modified source.",
-    "items": {
-      "additionalProperties": true,
-      "type": "object"
-    },
-    "type": "array"
-  },
-  "error": {
-    "description": "Failure message (present when ok is false).",
-    "type": "string"
-  },
-  "new_code": {
-    "description": "Modified .kcad.ts source (present on success). Caller persists it.",
-    "type": "string"
-  },
-  "ok": {
-    "description": "Whether the edit applied and re-evaluated cleanly.",
-    "type": "boolean"
-  }
-}

removedOutput schema / required
```
Removed value: -[
-  "ok"
-]
```

Changed1 schema field changedOct 9, 2026

changedInput schema / properties / sampling / description

Previous value: -"kind:'boundary' — OCCT NbPtsOnCur sampling parameter (default 15)."New value: +"kind:'boundary' — points sampled along each boundary (default 15)."

Changed14 schema fields changedSep 21, 2026

addedInput schema / properties / angle_deg

Added value: +{
+  "description": "kind:'draft' — draft angle in degrees [0, 90]. The face is tapered outward by this angle relative to the pull direction.",
+  "maximum": 90,
+  "minimum": 0,
+  "type": "number"
+}

changedInput schema / properties / binding_name / description

Previous value: -"JS const name for the new Surface binding (kind:'nurbs' default surface_<N>; kind:'boundary' default _surface_<N>)."New value: +"JS const name for the new binding (kind:'nurbs' default surface_<N>; kind:'boundary' default _surface_<N>; kind:'trim' default _trimmed_<N>; kind:'sew' default _sewn_<N>; kind:'draft' default _drafted_<N>)."

addedInput schema / properties / by_binding

Added value: +{
+  "description": "kind:'trim' — JS variable name of the cutter Surface (must be declared in source). Shape/Curve3D cutters are deferred.",
+  "type": "string"
+}

addedInput schema / properties / face

Added value: +{
+  "description": "kind:'draft' — face selector for the face(s) to taper. Accepts a canonical name (top/bottom/front/back/left/right), a user label declared via faceLabels, or a FaceQuery descriptor string.",
+  "type": "string"
+}

changedInput schema / properties / kind / description

Previous value: -"Which surface-construction path to use."New value: +"Which surface-construction or surface-finishing path to use: 'nurbs' | 'boundary' | 'trim' | 'sew' | 'draft'."

changedInput schema / properties / kind / enum

Previous value: -[
-  "nurbs",
-  "boundary"
-]New value: +[
+  "nurbs",
+  "boundary",
+  "trim",
+  "sew",
+  "draft"
+]

addedInput schema / properties / neutral_plane

Added value: +{
+  "description": "kind:'draft' — parting-line face (the plane where drafted faces remain fixed). Defaults to `face` if omitted.",
+  "type": "string"
+}

addedInput schema / properties / op

Added value: +{
+  "description": "kind:'trim' — 'trim' discards the smaller half (calls .trimTo()); 'split' retains both halves (calls .split()).",
+  "enum": [
+    "trim",
+    "split"
+  ],
+  "type": "string"
+}

addedInput schema / properties / pull_dir

Added value: +{
+  "description": "kind:'draft' — demoulding direction as [x, y, z]. Defaults to the face normal at lower time.",
+  "items": {
+    "type": "number"
+  },
+  "maxItems": 3,
+  "minItems": 3,
+  "type": "array"
+}

addedInput schema / properties / require_closed

Added value: +{
+  "description": "kind:'sew' — when true the lowerer emits feature.surface-sew.open-shell if the stitched result is not a watertight solid.",
+  "type": "boolean"
+}

addedInput schema / properties / shape_binding

Added value: +{
+  "description": "kind:'draft' — JS variable name of the Shape to taper (must be declared in source).",
+  "type": "string"
+}

addedInput schema / properties / surface_binding

Added value: +{
+  "description": "kind:'trim' — JS variable name of the Surface to trim/split (must be declared in source).",
+  "type": "string"
+}

addedInput schema / properties / surface_bindings

Added value: +{
+  "description": "kind:'sew' — JS variable names of the surfaces to stitch into a solid (each must be declared in source).",
+  "items": {
+    "type": "string"
+  },
+  "minItems": 1,
+  "type": "array"
+}

addedInput schema / properties / tolerance

Added value: +{
+  "description": "kind:'sew' — edge-merging tolerance in mm (default 1e-6). Edges within this distance are merged.",
+  "type": "number"
+}

Changed2 schema fields changedJun 19, 2026

changedInput schema / properties / continuity / description

Previous value: -"kind:'boundary' — continuity grade applied to every edge ('C0' | 'C1' | 'C2'), or an array of 4 grades (one per edge). Default 'C0'."New value: +"kind:'boundary' — continuity grade applied to every edge ('C0' | 'C1' | 'C2'), or an array of 4 grades (one per edge, bottom/right/top/left order). Default 'C0'."

addedInput schema / properties / continuity / oneOf

Added value: +[
+  {
+    "enum": [
+      "C0",
+      "C1",
+      "C2"
+    ],
+    "type": "string"
+  },
+  {
+    "items": {
+      "enum": [
+        "C0",
+        "C1",
+        "C2"
+      ],
+      "type": "string"
+    },
+    "maxItems": 4,
+    "minItems": 4,
+    "type": "array"
+  }
+]

Changed2 schema fields changedJun 19, 2026

changedInput schema / properties / continuity / description

Previous value: -"kind:'boundary' — continuity grade applied to every edge ('C0' | 'C1' | 'C2'), or an array of 4 grades (one per edge, bottom/right/top/left order). Default 'C0'."New value: +"kind:'boundary' — continuity grade applied to every edge ('C0' | 'C1' | 'C2'), or an array of 4 grades (one per edge). Default 'C0'."

removedInput schema / properties / continuity / oneOf

Removed value: -[
-  {
-    "enum": [
-      "C0",
-      "C1",
-      "C2"
-    ],
-    "type": "string"
-  },
-  {
-    "items": {
-      "enum": [
-        "C0",
-        "C1",
-        "C2"
-      ],
-      "type": "string"
-    },
-    "maxItems": 4,
-    "minItems": 4,
-    "type": "array"
-  }
-]

Changed2 schema fields changedJun 15, 2026

changedInput schema / properties / continuity / description

Previous value: -"kind:'boundary' — continuity grade applied to every edge ('C0' | 'C1' | 'C2'), or an array of 4 grades (one per edge). Default 'C0'."New value: +"kind:'boundary' — continuity grade applied to every edge ('C0' | 'C1' | 'C2'), or an array of 4 grades (one per edge, bottom/right/top/left order). Default 'C0'."

addedInput schema / properties / continuity / oneOf

Added value: +[
+  {
+    "enum": [
+      "C0",
+      "C1",
+      "C2"
+    ],
+    "type": "string"
+  },
+  {
+    "items": {
+      "enum": [
+        "C0",
+        "C1",
+        "C2"
+      ],
+      "type": "string"
+    },
+    "maxItems": 4,
+    "minItems": 4,
+    "type": "array"
+  }
+]

Changed1 schema field changedJun 15, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": true,
+  "properties": {
+    "binding_name": {
+      "description": "JS const name bound to the new construct (when one was created).",
+      "type": "string"
+    },
+    "diagnostics": {
+      "description": "Diagnostics from re-evaluating the modified source.",
+      "items": {
+        "additionalProperties": true,
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "error": {
+      "description": "Failure message (present when ok is false).",
+      "type": "string"
+    },
+    "new_code": {
+      "description": "Modified .kcad.ts source (present on success). Caller persists it.",
+      "type": "string"
+    },
+    "ok": {
+      "description": "Whether the edit applied and re-evaluated cleanly.",
+      "type": "boolean"
+    }
+  },
+  "required": [
+    "ok"
+  ],
+  "type": "object"
+}

AddedJun 13, 2026

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Input Schema

Output Schema

Schema Changelog

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