The package boundary is intentionally narrow: it owns artifact generation, validation, selector/topology extraction, mesh settings, source hashing, and the cadpy-step-artifact CLI. It also includes small generated-script helpers such as cadpy.assembly.AssemblyHelper, which wraps native build123d labels, joints, and compounds without owning skill-specific UX. Prompts, viewer UI, and snapshot job orchestration stay in their owning skills.

Local Development

Install it editable into the repo CAD runtime when working on the source package directly:

./.venv/bin/python -m pip install -e packages/cadpy

After that, changes under packages/cadpy/src/cadpy are immediately visible to local source checkouts that import the package directly.

On develop, the CAD skill and root Viewer point at this package through the development symlinks skills/cad/scripts/packages/cadpy and viewer/packages/cadpy. Keep those links intact with scripts/dev/setup-symlinks.sh --check.

Production Bundling

Build a wheel and install it into each skill's bundled Python environment during packaging:

./.venv/bin/python -m build packages/cadpy
python -m pip install packages/cadpy/dist/cadpy-*.whl

The CAD and cad-viewer skills should depend on the package artifact they bundle, not on skills/cad or the repository root. Production packaging vendors installable packages under skills/cad/scripts/packages/cadpy and skills/cad-viewer/scripts/viewer/packages/cadpy; production packaging can also set VIEWER_CAD_PYTHON to a skill-local Python runtime with this package installed.