Python Packaging

• Declare everything in pyproject.toml, never add setup.py, setup.cfg or requirements.txt
• Set requires-python = ">={{python_min_version}}" and do not use syntax newer than that
• Use the src/ layout with one package directory, so tests import the installed package
• Declare dependencies with a lower bound and only add an upper bound when a break is known
• Keep development dependencies in a dependency group, out of the runtime dependencies
• Commit the lockfile, and treat it as the source of truth for reproducible installs
• Never commit a virtual environment, and never install into the system interpreter
• Expose entry points through [project.scripts] rather than telling users to run a file path
• Keep the version in one place, and derive it from the package metadata at runtime