Gen Sketch

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:setup executable first.

3. Choose a representation

4. Author and register

Write the sketch file first, then register it:

pc add sketch <kind> <name>.<ext>       # e.g. pc add sketch build123d profile.py

• 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                          # the -O directory must already exist
pc render -s -t svg -O /tmp/pc-render <name>     # writes /tmp/pc-render/<name>.svg

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>.