Minimal, explicit configuration files

Configuration and dependency files (requirements files, setup.py/setup.cfg, .gitignore) should be scoped precisely to what is actually needed and should declare constraints explicitly rather than relying on implicit or environment-specific behavior.

• Only list dependencies that are genuinely required for the stated purpose of a file. For example, a typing.in requirements file used for running mypy should not also list pytest if tests aren’t type-checked.
• Never commit IDE- or machine-specific generated files (e.g. .idea/*.iml, local virtualenv paths) to the repository. Add these to .gitignore or .git/info/exclude so they stay local to each developer’s environment.
• Prefer configuration options that work across environments instead of tool- or platform-specific ones. For instance, favor a portable tag_build/tag_date scheme in setup.cfg over tag_svn_revision, which only applies when using Subversion.
• Make supported environments and versions explicit in configuration, e.g. set python_requires in setup.py to state exactly which Python versions are supported, instead of leaving this implicit or undocumented.

Following this standard keeps configuration files lean, portable, and self-documenting, reducing confusion about what a project actually depends on or supports.</description>