| name | gen-sketch |
| description | Generate a PartCAD 2D sketch from a natural-language description by authoring the sketch (build123d / cadquery / dxf / svg / basic) and validating it with the PartCAD CLI. Use for /pc:gen-sketch or when the user asks to generate, create, or draw a 2D sketch, profile, outline, or blueprint. |
pc:gen-sketch
Generate one PartCAD sketch — a 2D profile — from a description. You author
the sketch yourself and prove it renders with the PartCAD CLI. There is no
built-in ai-* sketch type; you are the model. The hard requirement: the
sketch renders without errors.
The flow mirrors /pc:gen-part, adapted to 2D. Treat it as a strong default, not
a script — but always finish by rendering. (Sketches are not manufacturable, so
unlike parts they need no manufacturable: flag and skip the cam tests.)
1. Understand the request
$ARGUMENTS is the description. Read it and any requirements, and view
reference images directly. Ask the user to clarify only load-bearing
ambiguities. Work in millimeters unless told otherwise.
2. Make sure PartCAD is available
Resolve a command as /pc:init does (pc, then partcad, then
python -m partcad_cli.click.command). If none is found, stop and run
/pc:install executable first.
3. Choose a representation
| Kind | Good for |
|---|
build123d | parametric 2D sketches (recommended default) |
cadquery | fluent 2D sketching |
dxf | a DXF outline |
svg | an SVG outline |
basic | simple primitive-based sketches |
4. Author and register
Write the sketch file first, then register it:
pc add sketch <kind> <name>.<ext>
- build123d / cadquery (Python): import everything you use (including
math
and the library itself); expose the 2D result with show_object(<sketch>); do
not export anything.
- dxf / svg: write the outline file directly.
Record the description in the sketch's desc: in partcad.yaml. If you started
the project with pc init, delete the empty null sections it leaves.
5. Render, compare, and iterate
Rendering is the build gate. Sketches render to SVG:
mkdir -p /tmp/pc-render
pc render -s -t svg -O /tmp/pc-render <name>
View /tmp/pc-render/<name>.svg and compare it against the description — the
outline and every stated dimension. Fix any error or mismatch, then re-render.
Iterate until it is right.
6. Finalize
Summarize what you drew — key dimensions and assumptions — and how to view it:
pc inspect -s <name>.
