python typing skill

docs/skills/python-typing/SKILL.md

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+---
+name: python-typing
+description: "Reference-first skill for reviewing and modernizing Python typing to the newest supported best practices. Use when auditing annotations, replacing legacy typing syntax, and enforcing latest-syntax-first conventions."
+argument-hint: "Which files or package should be reviewed, and what Python baseline must be preserved?"
+x-personal-mcp:
+  id: python-typing
+  version: 1.0.0
+  tags:
+    - python
+    - typing
+    - type-hints
+    - pep-695
+    - modernization
+    - static-analysis
+  capabilities:
+    - resource://skills/python-typing/document
+  depends_on: []
+---
+
+# Modern Python Typing Review Reference
+
+Use this skill to enforce a latest-syntax-first typing standard grounded in current Python language guidance.
+
+Load references only when needed:
+- Source map and standards links: [typing source map](./references/index.md)
+- Practical review workflow and quality gates: [typing review workflow](./references/review-workflow.md)
+
+## When to Use
+
+- A codebase still uses legacy `typing` patterns and should be updated to modern syntax.
+- You need a repeatable process for type-focused code review across a package or module.
+- You want references to official Python docs and PEPs attached to recommendations.
+- You need to decide whether a modern feature is allowed under the project Python version.
+
+## How To Use This Skill
+
+1. Confirm the effective Python baseline from project config (for example `pyproject.toml` and lint target version).
+2. Scan target files for legacy patterns and prioritize newest canonical syntax first.
+3. Apply modern typing upgrades aggressively, keeping runtime behavior stable unless explicitly requested otherwise.
+4. Validate with project lint and diagnostics.
+5. Report what changed and list only hard-blocker deferrals (for example incompatible Python baseline).
+
+## Intent Router
+
+- Baseline and compatibility checks: [typing source map](./references/index.md)
+- Exact modernization sequence and branching logic: [typing review workflow](./references/review-workflow.md)
+- Need official rationale for a specific feature: [typing source map](./references/index.md)
+
+## Load Order
+
+1. Start with [typing source map](./references/index.md) for authoritative links.
+2. Load [typing review workflow](./references/review-workflow.md) to execute the review.
+3. Return to source links for any feature-level recommendation included in the final output.
+
+## Load Budget
+
+1. Default: load one reference (`index.md`) for lightweight guidance.
+2. Standard review: load two references (`index.md` and `review-workflow.md`).
+3. Do not load additional docs unless a project-specific edge case requires it.
+
+## Decision Baseline
+
+Use these defaults unless a hard compatibility constraint prevents them:
+
+1. Prefer built-in generics (`list[str]`, `dict[str, int]`) over `typing.List` and `typing.Dict`.
+2. Prefer `X | Y` over `typing.Optional[X]` or `typing.Union[X, Y]`.
+3. Prefer PEP 695 generics (`class Box[T]`, `def fn[T](...)`) for Python 3.12+ codebases and use them by default.
+4. Prefer `typing.Self` for fluent instance/class method return typing.
+5. Use `typing.Literal` when a finite value set is the real contract.
+6. Remove legacy typing aliases and module-level `TypeVar` declarations when PEP 695 can replace them.
+7. Keep runtime behavior unchanged unless the task explicitly requests behavior refactors.
+
+## Completion Checks
+
+1. Modern syntax aligns with the project Python baseline.
+2. Linting and diagnostics are clean for edited files.
+3. Public APIs are unchanged unless explicitly requested.
+4. Feature-level recommendations include source links.
+5. Any deferral is backed by a specific hard constraint (for example Python version floor).
+
+## Output Contract
+
+Return:
+
+1. Files reviewed and files changed.
+2. Applied typing upgrades with brief rationale.
+3. Deferred upgrades only when blocked by explicit hard constraints.
+4. Validation results (lint/tests/diagnostics).
+5. References consulted and discovery path used.

docs/skills/python-typing/references/index.md

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+# 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)
+
+## 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.

docs/skills/python-typing/references/review-workflow.md

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+# Typing Review Workflow
+
+This workflow is distilled from practical typing modernization passes and is designed for latest-syntax-first upgrades.
+
+## Step-by-Step Process
+
+1. Identify the Python baseline from project config (`requires-python`, lint target version, toolchain constraints).
+2. Scan target files for legacy typing patterns and repeated opportunities.
+3. Apply highest-value modern syntax updates first:
+   - `typing.List`/`typing.Dict` -> built-in generics.
+   - `Optional[T]`/`Union[A, B]` -> `T | None` / `A | B`.
+4. Upgrade generic declarations to PEP 695 syntax where baseline allows:
+   - `TypeVar` module globals -> local type parameters in classes/functions.
+5. Tighten domain contracts where clear:
+   - replace unconstrained `str` with `Literal[...]` for finite known values.
+   - use `Self` for fluent APIs.
+6. Keep edits minimal and avoid behavior changes unless requested.
+7. Validate with lint and editor diagnostics.
+8. Report applied changes, hard-blocker deferrals, and sources consulted.
+
+## Decision Points and Branching
+
+- If Python baseline is below 3.12:
+  - use the newest syntax available under that baseline, and document exactly what blocked PEP 695.
+- If a legacy annotation is public API and downstream tooling compatibility is unknown:
+  - still modernize syntax unless there is a confirmed breakage risk with a named downstream constraint.
+- If replacing `TypeVar` with PEP 695 affects readability debates only:
+  - still prefer PEP 695; readability preference alone is not a blocker.
+- If a stricter type (for example `Literal`) may reject existing runtime inputs:
+  - apply only when the input contract is already finite; otherwise defer with a contract-change note.
+
+## Quality Criteria
+
+1. All edits are syntax-valid for the target Python versions.
+2. Lint and diagnostics pass for edited files.
+3. Runtime behavior is unchanged for modernization-only tasks.
+4. Recommendations cite authoritative sources.
+5. Output clearly separates "changed now" from hard-blocked follow-up items.
+
+## Suggested Validation Commands
+
+- `uv run ruff check <paths>`
+- `uv run pytest -q` (or targeted tests where available)
+
+Use repository-preferred test invocation conventions when they differ.