Reusable code that must be available to more than one skill lives here as a normal Python package. Skills should import the package they bundle, not sibling skill source directories.

Small shared runtime helpers such as cadpy_metadata should still use this pattern: source lives once under packages/, then each consuming skill gets its own generated scripts/packages/<package> copy.

For local development, install packages editable into the repo venv. For production packaging, build wheels or install into a skill-local Python target such as vendor/python.