You're about to ship your SaaS. The landing page looks gorgeous. You copy the URL, paste it into Twitter. The preview shows your favicon, your default title, your base description. No product screenshot. No specific page context. Just... nothing. This is the OGP (Open Graph Protocol) blindspot that haunts every SPA developer. Your single-page application renders content client-side, which means social media crawlers — Twitter's crawler, Facebook's crawler, Slack's link previews — see an empty shell. No meta tags. No page-specific content. Just the shell your index.html ships with. I've been digging into how Japanese developers tackle this problem on Qiita, and there's a particularly elegant approach using CloudFront Functions that deserves more attention in Western dev circles. The Root Problem: Why SPAs Break Social Previews Social media crawlers execute JavaScript, but they do it with a timeout. Most crawlers give your page seconds to render before they snapshot the DOM.…