We could already support ruff format or ruff fmt or ruff rtrip (in Astor parlance). Soon there will be more tools and sub-commands, e.g., #423.

A few open questions:

• Do we want to move the core linting functionality to ruff check? Or leave it as a "default" sub-command? (I think the latter can cause a variety of ambiguities but it'd be nice to do something backwards compatible here.)
• Do we want to expose a dedicated ruff fix command in lieu of or in addition to --fix? Perhaps ruff fix applies fixes recursively.