We analyzed a core payments module that had grown unstable due to quick fixes over several years. Our approach was to refactor the code, introduce linting rules, and rewrite critical functions with performance in mind. Key focus areas included database queries, caching, and error handling.

// Old implementation
function calculateTotal(items) {
  let total = 0;
  for (let i = 0; i < items.length; i++) {
    total += items[i].price;
  }
  return total;
}
// New implementation with reduce
const calculateTotal = (items) =>
  items.reduce((acc, item) => acc + item.price, 0

This case demonstrates how structured technical work — from code review to modular improvements — can extend the life of existing systems and bring immediate, measurable benefits.