refactor

When to use

The user wants code cleaner / simpler / restructured, with the same observable behaviour.

How

1. Read the file and its tests first.
2. Make one focused change at a time with edit_file (exact, unique old_string).
3. Preserve behaviour — outputs must not change. Keep names and style consistent.
4. Suggest running the tests after each change.

Avoid

• Behaviour changes smuggled into a "refactor".
• Rewriting unrelated code.
• Big-bang rewrites instead of small, safe steps.

Done well

The code reads better, the tests still pass, and you can state in one line why each change is behaviour-preserving.