How I took a frontend that grew without a plan, measured the mess, and moved it to clean architecture in eleven small PRs, finding real bugs along the way. When I started building our markets-data platform, I didn't think about architecture. I focused on getting equities, indices, and screen prices. It's a Next.js App Router project that shows stock exchange data, news, watchlists, and paid subscriptions. That worked until it didn't. As the app grew, I adopted clean architecture for ne...