ref-sp-py-pythonlisted

# Python ## Purpose Provide portable Python defaults that emphasize explicit typing, simple structure, maintainable CLIs, and focused tests. ## When to use this skill - Writing or refactoring Python application code. - Designing a Python CLI or maintenance script. - Choosing how to type shared data and interfaces. - Deciding where tests should live and what they should cover. - Reviewing Python code for readability and long-term maintainability. ## Scope Boundaries - Use this skill for portable Python structure, typing, CLI, and testing guidance. - Use `ref-sp-dev-coding-patterns` for language-agnostic naming, comment, and CLI ergonomics defaults. - Use `ref-sp-dev-projects-architecture` for shared-utility thresholds and product-versus-maintenance boundaries. - Use a repo's own repo-conventions skill (in this repo, `ref-sp-dev-repo-conventions`) when the question is about that repository's exact package names, top-level folders, or validation commands. ## Defaults - Prefer modern Python with type hints throughout public and shared code. - If the repo already targets a modern Python baseline such as 3.14+, do not add `from __future__ import annotations` or similar compatibility boilerplate just to mimic older code. - Prefer inferred return types for local helpers when the type checker can infer them cleanly; add return annotations when the function defines an API contract or inference would hide ambiguity. - Prefer `pathlib.Path` over raw path strings. - Prefer datacla