refactor

name	refactor
description	Safely refactor code with test coverage as a safety net
argument-hint	[target to refactor. File, function, or pattern]
disable-model-invocation	true

Refactor $ARGUMENTS safely.

Process

1. Understand the current state

• Read the code and its tests
• Identify what the code does, who calls it, and what it depends on
• If there are no tests, WRITE TESTS FIRST. You need a safety net before changing anything

2. Plan the refactoring

• State what you're changing and why (clearer naming, less duplication, better structure)
• List the specific transformations (extract function, inline variable, move module, etc.)
• Check whether this changes any external behavior. If it does, it isn't a refactor — reconsider.

3. Make changes in small, testable steps

• One transformation at a time
• Run the tests after EACH step, not just at the end
• If a test breaks, undo the last step and make a smaller change

4. Verify

• All existing tests pass
• Lint and typecheck pass
• The public API is unchanged (unless changing it was the explicit goal)
• The code is objectively simpler: fewer lines, fewer branches, clearer names

Rules

• If you can't run the tests, don't refactor
• Never mix refactoring with behavior changes in the same commit
• If the refactoring is large (10+ files), split it across multiple commits