If you're an engineering leader at a dev-tools company, an AI infrastructure platform, or an API-first SaaS, there's a good chance your marketing site is a React SPA — Vite, Create React App, or something similar — that your team built five-to-eight years ago, shipped, and never had a reason to revisit. Conversions weren't bad. The site loaded. Your engineers respected it because they wrote it. There was no fire. Quietly, though, your marketing pages may not be in Google's index. Or they may be in the index in a degraded form that's worse than not being indexed at all. Either way, the searches that should bring buyers to your pricing page or your developer-experience post are going to your competitors instead — competitors who probably migrated to Next.js the same year you decided not to. I want to walk through one site in detail to show what this actually looks like.…