Chromy/plans/06-add-ruff-mypy-configuration.md

6. Add Ruff and Mypy Configuration

Summary

Add linting, formatting, and static type checking configuration to pyproject.toml. Do not add pytest configuration for this improvement.

Implementation Steps

• Add ruff and mypy to the development dependency group.
• Configure Ruff formatting and lint rules in pyproject.toml.
• Configure mypy in strict or near-strict mode suitable for the current Chroma and third-party boundaries.
• Add README development commands for uv run ruff check ., uv run ruff format ., and uv run mypy ..
• Fix only minimal configuration blockers in this plan; broad type modernization belongs to the type-hints plan.

Public Interface Changes

• No runtime CLI behavior changes.
• Development workflow gains standard lint, format, and type-check commands.

Test Plan

• Run uv run ruff check ..
• Run uv run ruff format --check ..
• Run uv run mypy ..
• Confirm no pytest configuration is added as part of this plan.

Assumptions

• Pytest is intentionally out of scope for this improvement.
• Strict mypy may need targeted ignores for third-party packages that do not expose complete typing.