Refactor

Refactor $ARGUMENTS to improve readability, structure, and maintainability while keeping observable behavior exactly the same. If $ARGUMENTS is empty, ask which file or function to target before making any changes.

1. Establish a baseline

Before touching anything, understand the current behavior and how it is verified.

• Read $ARGUMENTS and the code that calls it. Note the public interface: function signatures, exported symbols, and any side effects (I/O, network, mutation, logging).
• Find the relevant tests. Run them to confirm they pass before you start, so you have a known-good baseline.

# Adjust to the project's test runner
npm test            # or: pytest, go test ./..., cargo test

If there are no tests covering the target, say so. Add a minimal characterization test that captures current behavior before refactoring, or ask the user how to proceed.

2. Identify what to improve

Look for concrete, well-known issues rather than stylistic preference:

• Naming — vague or misleading identifiers (data, tmp, doStuff).
• Duplication — repeated logic that can be extracted into one place.
• Long functions — units doing several jobs that should be split.
• Deep nesting — guard clauses and early returns can flatten control flow.
• Dead code — unused variables, unreachable branches, stale comments.
• Leaky structure — mixed levels of abstraction in one function.

3. Apply changes in small steps

Make one focused transformation at a time. Prefer many small, verifiable edits over one large rewrite.

A typical move is replacing nested conditionals with guard clauses:

// Before
function getDiscount(user) {
  if (user) {
    if (user.isActive) {
      return user.isPremium ? 0.2 : 0.1;
    }
  }
  return 0;
}
 
// After
function getDiscount(user) {
  if (!user || !user.isActive) return 0;
  return user.isPremium ? 0.2 : 0.1;
}

After each meaningful step, re-run the tests so a regression is caught immediately and isolated to the change that caused it.

4. Verify behavior is unchanged

• Run the full test suite again; it must pass with no modifications to the assertions.
• Run the linter and type checker to confirm nothing was broken.

npm run lint
npm run build   # or the project's typecheck command

5. Summarize

Report back concisely:

• What changed — the specific refactorings applied (e.g. "extracted validateInput, flattened nesting in parse").
• Why — the readability or structure problem each change addressed.
• Verification — that tests, lint, and types still pass.
• Follow-ups — anything out of scope you noticed (suspected bugs, missing test coverage) listed separately, not acted on.