writing-pythonlisted

# Python Development Use this only for Python 3.12+ code. Keep language-agnostic rules out of this skill. ## Read First Read [principles.md](references/principles.md) before generating or changing Python code. ## Core Rules - Prefer existing project patterns over these defaults. - Inspect the project Python target before using 3.12-only syntax. - Prefer stdlib and existing dependencies before adding packages. - Validate untyped boundary input before it spreads. ## Conditional References - [patterns.md](references/patterns.md) — read for module design, typing, async, config, file I/O, and error patterns. - [cli.md](references/cli.md) — read before writing or changing Python CLIs. - [testing.md](references/testing.md) — read before adding or reshaping Python tests. ## Verification Run project-configured tests, lint, format, and type checks. Prefer pytest, ruff, and pyright when present. If a tool is not configured, say so and run the closest available gate. If a check fails, diagnose the cause, make a targeted fix, and rerun the relevant check. ## Python-Specific Failure Cases - No clear project root: locate `pyproject.toml` before editing or choosing commands. - Unknown Python target: inspect `pyproject.toml`, `.python-version`, CI, or lockfiles before using 3.12-only syntax. - Type checker reports missing attributes: check imports, package exports, and runtime shape before loosening types. ## Final Response Include: - changed files - checks run and results - ch