Refactor

Refactor code safely using characterization tests, incremental changes, and continuous verification. Every change preserves existing behavior while improving code structure, readability, and maintainability.

Refactoring Goal

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Core Principle: Behavior Preservation

CRITICAL: Refactoring changes code structure WITHOUT changing behavior. Every step must be verified against existing tests. If tests break, the refactoring introduced a bug — revert and retry.

Anti-Hallucination Guidelines

1. Read before changing — Never refactor code that has not been read and understood. Understand all callers and dependencies first.
2. Test before and after — Run the full test suite before starting. Run it again after every incremental change. The results must match.
3. Characterization tests first — If test coverage is insufficient for the target code, write characterization tests that capture current behavior BEFORE refactoring.
4. Incremental changes — Make one small, verifiable change at a time. Never combine multiple refactoring steps into a single edit.
5. No feature changes — Do not add features, fix bugs, or change behavior during refactoring. These are separate tasks.