refactor

name	refactor
description	Refactoring process with test safety. Invoke immediately when user or document mentions refactoring, or proactively when code gets too complex or messy.
triggers	["refactor this code","refactor the code","refactoring code","clean up code","extract method"]
allowed-tools	Read Glob Write Bash

Refactoring Production Code

Work autonomously as much as possible. Start with the simplest thing or file and proceed to the more complex ones.

Stages

1. Prep
2. Main Refactoring
3. Final Evaluation
4. Summary

Test Code Policy

Do not change test code during refactoring, except:

• Renames that follow production code renames (imports, function calls)
• Import path updates if something moved

Never change test assertions, test data, or test logic.

1. Prep

• Determine scope: use specified files, or identify related files (imports, shared functionality), or ask user
• Add files in scope to todo list
• Find or create ./test.sh, verify all tests pass
• Remove comments from files in scope (commit per file)
• Create REFACTORING_SUMMARY.md in the project root with the following initial content:

  # Refactoring Summary
  ## Baseline
  - Files in scope: {list of files}
  - Test result: {PASS/FAIL with test count}
  ## Steps
  

2. Main Refactoring

Code Style

Prefer self-explanatory, readable code over comments.

• Use functional helper methods for clarity
• Remove dead code
• Extract paragraphs into methods
• Use better variable names
• Remove unused imports
• Remove unhelpful local variables
• Look for opportunities to simplify
• Use domain language - name things for what they ARE, not how they're implemented
• Keep consistent abstraction levels within methods

Example — extract method and rename variable:

Before:

// apply discount
const x = order.items.reduce((sum, i) => sum + i.price, 0);
return x * (1 - order.dc);

After:

const subtotal = sumItemPrices(order.items);
return subtotal * (1 - order.discountRate);

function sumItemPrices(items) {
  return items.reduce((sum, item) => sum + item.price, 0);
}

Example — remove dead code and use domain language:

Before:

function process(u, t) {
  // TODO: remove legacy path
  if (false) { return legacyProcess(u, t); }
  return chargeCard(u.card, t.amount);
}

After:

function processPayment(user, transaction) {
  return chargeCard(user.card, transaction.amount);
}

Process

For each refactor:

1. Ensure all tests pass
2. Choose and perform the simplest possible refactoring (one at a time)
3. Ensure all tests pass after the change
4. Commit each successful refactor with the message format: "- r " (the message must include the "- r" prefix) Prefer small granular commits. If applying the same refactoring pattern to multiple locations, change one location at a time and commit each separately.
5. Append to REFACTORING_SUMMARY.md:

   ### Step {N}: {refactoring description}
   - Commit: `- r {message}`
   - Test result: {PASS with test count}
   - Files changed: {list}
   

6. Provide a status update after each refactor

3. Final Evaluation

When you see no more obvious refactoring opportunities, say "Entering final evaluation."

Shift focus: you've been implementing. Now become a critic. Your job is to find problems, not produce code.

Re-read Code Style guidelines. Look at each file in scope. Consider blind spots - what improvements haven't we even considered that would make the code better, easier, more maintainable?

For each file, find ONE thing that could be better. If you find something:

1. Fix it using the same refactoring process (test, change, test, commit)
2. Look again; fixing one thing often reveals the next

Repeat until you find nothing more to improve.

4. Summary

Provide a high-level summary of the refactoring:

• List each file that was touched
• Describe the key improvements made in each file

Append a final section to REFACTORING_SUMMARY.md:

## Final
- Total steps: {N}
- Files touched: {list of all files changed}
- All commits: {list of commit messages}
- Final test result: {PASS with test count}

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This skill was originally adapted from Llewellyn Falco's refactoring process. See credits.md for attribution.