Fitz framework achieves server-to-WASM DOM handoff without rebuilding the page

Fitz, a web framework using WebAssembly, has implemented isomorphic hydration that allows a server-rendered DOM to be adopted directly by a client-side WASM application without wiping or rebuilding the page. The server computes a full render of the component tree and serializes state, which the client then restores — including complex types like lists, maps, and nullable values — via a JSON payload. Instead of reconciling differences like React does, Fitz walks the existing DOM node-for-node, attaching event listeners to already-present elements. The approach requires no framework runtime shipped to the client, distinguishing it from JS-based solutions such as React/Next.js or Astro islands. Hydration is currently opt-in per component, with full auto-hydration planned as a future improvement.