SSR and Islands

zfb pages are server-rendered by default. That means every route in pages/ is turned into a real HTML file at build time, with the markup already in place when the browser receives it. Search engines, RSS readers, and link previews all see the same content the user does.

For interactive bits — a counter, a theme toggle, a search box — zfb uses the island pattern. A component file marked "use client" becomes a hydration boundary: the server renders its initial HTML, and the client loads just enough JavaScript to wake up that one widget. Everything else on the page stays static.

This trade is the whole point of the architecture. You get the SEO and performance of a static site, plus the interactivity of a SPA exactly where you ask for it, and nowhere else. The <ThemeToggle /> in this example is the smallest possible demonstration of the pattern.