greenfield-python-stacklisted

# Greenfield Python Stack Opinionated defaults for a new Python service in 2026. Time-stamped: these reflect today's tools and will go stale — treat them as a starting point to adapt. For a non-trivial new project, run megapowers:brainstorming and megapowers:writing-plans first (if installed) — this skill supplies the stack, not the process. ## Toolchain (pin these) - **uv** — dependency + venv + lockfile manager. `uv init`, `uv add`, `uv run`, `uv sync`. One tool, fast, a real lockfile (`uv.lock`). Commit the lock. - **ruff** — lint *and* format (replaces black + flake8 + isort). `ruff check --fix` and `ruff format`. Enable a strict ruleset in `pyproject.toml`. - **pyright** (or **ty**) in **strict** mode — types are a correctness tool, not decoration. CI fails on a type error. - **pytest** — tests. `pytest-asyncio` for async tests. - **pydantic v2** — validation and settings (`pydantic-settings` for config from env). ## Layout `src/` layout so tests import the installed package, not the working dir: ``` myservice/ ├── pyproject.toml # deps, ruff, pyright, pytest config all here ├── uv.lock ├── src/myservice/ │ ├── __init__.py │ ├── main.py # app wiring only │ ├── api/ # routes │ ├── domain/ # logic, no framework imports │ └── db.py └── tests/ ``` Keep framework imports out of `domain/` — logic you can test without a server. ## Web: FastAPI + uvicorn FastAPI + pydantic v2 for typed request/response. Prefer `as