# Python Typing Source Map

Use this page as the canonical source index when making typing modernization recommendations.

## Core Language and Library Docs

- [Typing module documentation](https://docs.python.org/3/library/typing.html)
- [Typing specification (typing.python.org)](https://typing.python.org/)
- [Built-in types and generic aliases](https://docs.python.org/3/library/stdtypes.html)
- [Python language reference: `match` statement](https://docs.python.org/3/reference/compound_stmts.html#the-match-statement)
- [PEP 634: Structural Pattern Matching specification](https://peps.python.org/pep-0634/)
- [typing.cast reference (runtime no-op)](https://docs.python.org/3/library/typing.html#typing.cast)
- [Typing spec directives for `cast()`](https://typing.python.org/en/latest/spec/directives.html#cast)
- [Mypy type narrowing and casts guidance](https://mypy.readthedocs.io/en/stable/type_narrowing.html#casts)
- [Typing guide: exhaustiveness and `assert_never`](https://typing.python.org/en/latest/guides/unreachable.html#assert-never-and-exhaustiveness-checking)
- [Mypy: `Literal`/`Enum` exhaustiveness with `match`](https://mypy.readthedocs.io/en/stable/literal_types.html#exhaustiveness-checking)

## Tooling References

- [Astral ty documentation](https://docs.astral.sh/ty/)
- [Astral ty usage reference (this skill)](./astral-ty.md)

## Modernization PEPs

- [PEP 585: Type Hinting Generics In Standard Collections](https://peps.python.org/pep-0585/)
- [PEP 604: Allow writing union types as `X | Y`](https://peps.python.org/pep-0604/)
- [PEP 673: Self Type](https://peps.python.org/pep-0673/)
- [PEP 695: Type Parameter Syntax](https://peps.python.org/pep-0695/)

## Advanced Typing PEPs (Load on Demand)

- [PEP 612: Parameter Specification Variables](https://peps.python.org/pep-0612/)
- [PEP 646: Variadic Generics](https://peps.python.org/pep-0646/)
- [PEP 647: User-Defined Type Guards](https://peps.python.org/pep-0647/)
- [PEP 655: Required and NotRequired for TypedDict](https://peps.python.org/pep-0655/)
- [PEP 742: Narrowing types with TypeIs](https://peps.python.org/pep-0742/)

## Version Gate Reminder

Before recommending syntax upgrades, verify the project's supported Python range and lint target so recommendations match runtime constraints.