ST006: HasPyTyped

Overview

Checks that a py.typed marker file exists in the package directory.

The py.typed marker is required by PEP 561 for packages that include inline type annotations to be recognized by type checkers.

The check verifies that a py.typed file exists in your package directory:

The package name is derived from pyproject.toml, with hyphens converted to underscores.

Without py.typed, type checkers like mypy, pyright, and ty will not use your package’s type annotations:

Without py.typed:

# mypy: error: Skipping analyzing "your_package": module is installed,
# but missing library stubs or py.typed marker

With py.typed:

# mypy uses your package's type annotations
# IDE shows proper type hints and autocomplete

The file should be empty (or can contain a comment). Create it in your package directory:

For src layout:

touch src/my_package/py.typed

For flat layout:

touch my_package/py.typed

Most build backends include py.typed automatically. If not, add it explicitly:

For Hatchling (pyproject.toml):

[tool.hatch.build.targets.wheel]
include = ["src/my_package/py.typed"]

For Setuptools (pyproject.toml):

[tool.setuptools.package-data]
my_package = ["py.typed"]

For Setuptools (MANIFEST.in):

include src/my_package/py.typed

After installing your package:

pip install -e .
python -c "import my_package; import pathlib; print(pathlib.Path(my_package.__file__).parent / 'py.typed')"

Check that the py.typed file exists at the printed path.

You may want to skip this check if:

[tool.pycmdcheck]
skip = ["ST006"]

pycmdcheck --skip ST006