kernelcad

Add Curve

add_curve

Use this when you need a freeform/organic 3D curve — a body feature line, brow, spine rail, or G2 blend between panels — authored as a Curve3D into the user's .kcad.ts immediately before the last top-level return. One authoring path, selected by kind:

'nurbs' — insert a nurbsCurve(controlPoints, opts?) declaration. Pass controlPoints as a Vec3[] (mm, at least 2 points). Optional NURBS knobs: degree (default 3), rational weights, explicit knots, closed.
'hermite' — insert a hermiteG2(a, b) declaration: a quintic Hermite curve interpolating two endpoints with matching positions, tangents, and (optional) curvatures — bridges two curves with G2 continuity. Each endpoint is { point: Vec3, tangent: Vec3, curvature?: Vec3 } in mm; tangent magnitude ~ chord length; curvature defaults to [0,0,0] (G1-only). The returned binding has type Curve3D (peer to Shape / Surface) — consume it via add_variable_sweep (spine input), add_surface({ kind: 'boundary' }) (boundary curve), or downstream Curve3D-accepting features. Returns the modified code + diagnostics from re-evaluating. Side-effect-free. Each kind fails closed on its own missing required params.

Input Schema

TableJSON Schema

Name	Required	Description
`a`	No	kind:'hermite' — start endpoint.
`b`	No	kind:'hermite' — end endpoint.
`code`	Yes	The .kcad.ts source code.
`kind`	Yes	Which curve-construction path to use.
`knots`	No	kind:'nurbs' — optional explicit knot vector; missing => clamped-uniform inferred.
`closed`	No	kind:'nurbs' — optional periodic/closed-curve flag.
`degree`	No	kind:'nurbs' — curve degree; default 3 (cubic).
`weights`	No	kind:'nurbs' — optional rational weights, one per control point (same length as controlPoints).
`binding_name`	No	JS const name for the new Curve3D binding (default: _curve_<N>).
`controlPoints`	No	kind:'nurbs' — control points as Vec3 triples in mm; at least 2 entries.

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"
-]
```

Changed3 schema fields changedJul 18, 2026
- addedInput schema / properties / b / properties / curvature / description
```
Added value: +"Optional second derivative; defaults to [0, 0, 0] (G1-only)."
```
- addedInput schema / properties / b / properties / point / description
```
Added value: +"Endpoint position in mm."
```
- addedInput schema / properties / b / properties / tangent / description
```
Added value: +"First derivative of the curve at this endpoint."
```

Changed1 schema field changedJun 19, 2026

addedInput schema / allOf

Added value: +[
+  {
+    "if": {
+      "properties": {
+        "kind": {
+          "const": "nurbs"
+        }
+      }
+    },
+    "then": {
+      "required": [
+        "controlPoints"
+      ]
+    }
+  },
+  {
+    "if": {
+      "properties": {
+        "kind": {
+          "const": "hermite"
+        }
+      }
+    },
+    "then": {
+      "required": [
+        "a",
+        "b"
+      ]
+    }
+  }
+]

Changed1 schema field changedJun 19, 2026

removedInput schema / allOf

Removed value: -[
-  {
-    "if": {
-      "properties": {
-        "kind": {
-          "const": "nurbs"
-        }
-      }
-    },
-    "then": {
-      "required": [
-        "controlPoints"
-      ]
-    }
-  },
-  {
-    "if": {
-      "properties": {
-        "kind": {
-          "const": "hermite"
-        }
-      }
-    },
-    "then": {
-      "required": [
-        "a",
-        "b"
-      ]
-    }
-  }
-]

Changed1 schema field changedJun 15, 2026

addedInput schema / allOf

Added value: +[
+  {
+    "if": {
+      "properties": {
+        "kind": {
+          "const": "nurbs"
+        }
+      }
+    },
+    "then": {
+      "required": [
+        "controlPoints"
+      ]
+    }
+  },
+  {
+    "if": {
+      "properties": {
+        "kind": {
+          "const": "hermite"
+        }
+      }
+    },
+    "then": {
+      "required": [
+        "a",
+        "b"
+      ]
+    }
+  }
+]

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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