Refactoring Safely With AI

Refactoring means improving the structure of code without changing what it does. Renaming for clarity, splitting one big function into small ones, moving code to a better file. AI is very good at these mechanical tasks because they rarely require new ideas.

The safety net first

1. 1Make sure you have tests that pass before touching anything
2. 2If no tests exist, ask the AI to help write a few
3. 3Commit your changes to git so you can roll back
4. 4Only then start refactoring

Three refactors AI does well

// Before: one long function doing too much
function processOrder(order) {
  if (!order.email.includes("@")) throw new Error("bad email");
  const tax = order.total * 0.08;
  const shipping = order.total > 50 ? 0 : 9.99;
  const final = order.total + tax + shipping;
  db.save({ ...order, final });
  sendEmail(order.email, `Total: ${final}`);
}

// After: small, named functions a human can read
function validateOrder(order) {
  if (!order.email.includes("@")) throw new Error("bad email");
}

function calculateTotal(order) {
  const tax = order.total * 0.08;
  const shipping = order.total > 50 ? 0 : 9.99;
  return order.total + tax + shipping;
}

function processOrder(order) {
  validateOrder(order);
  const final = calculateTotal(order);
  db.save({ ...order, final });
  sendEmail(order.email, `Total: ${final}`);
}

Refactor prompts that work

• Rename `x`, `y`, `z` to descriptive names based on how they are used
• Extract the validation block into a function called `validateOrder`
• Move these helper functions into a new file called `utils/pricing.ts`
• Replace the switch statement with a lookup map

When to stop

Every refactor has a diminishing return. Rename until names are clear. Extract until functions fit on one screen. Stop when the next change would be a matter of taste, not clarity.

“Refactoring is a surgical act. AI hands you the scalpel, but you still choose where to cut.”

The big idea: refactoring is safe when behavior is pinned down by tests and changes are small. AI is ideal for mechanical restructuring, but you own the safety net.