modern-python-guidancelisted

# Modern Python Guidance Pre-generation design patterns that Ruff cannot auto-fix. Apply these transformations when writing or reviewing Python code. ## When to use - Writing new Python code (use modern patterns from the start) - Reviewing Python code (flag outdated patterns) - Migrating from Pydantic V1 to V2 - Upgrading Python version (check which new features are available) - Replacing legacy tooling (setup.py, flake8, pip) ## Dependency applicability Before applying a framework or tool pattern, inspect project evidence or explicit overrides with `mpg search ... --project-dir .` / `--dependency-version KIND:NAME=VERSION`, or the equivalent MCP arguments. Requirements use AND semantics. - `confirmed`: evidence proves every required dependency; apply only after the guide's other caveats. - `incompatible`: never auto-apply known-incompatible guidance. - `unknown`: not confirmation; verify the target environment before changing code. Do not infer it from mpg's interpreter, optional/group dependencies, or an ambiguous lockfile. ## Embedded patterns (high-frequency, Ruff-uncovered) ### Pydantic V2 (>=3.9) - `@validator("f")` → `@field_validator("f")` - `@root_validator` → `@model_validator(mode="after")` - `class Config:` → `model_config = ConfigDict(...)` - `orm_mode` → `from_attributes`, `allow_population_by_field_name` → `populate_by_name` - `.parse_obj(d)` → `.model_validate(d)`, `.parse_raw(j)` → `.model_validate_json(j)` - `.dict()` → `.model_dump()`, `.json()` →