Problem
What real problem does this solve? Who hits it?

Proposed change
What you'd like reasonix to do differently. Include a sketch of the
UX or API if relevant.

Alternatives considered
What else you tried or thought about. "I just want it" is not an
alternative.

Scope check

• This belongs in core reasonix (not better as a separate npm package)
• I've read CLAUDE.md and CONTRIBUTING.md