Client Components Are Server-Rendered to HTML Before Client-Side Hydration

This indicates a misconfiguration; 'use client' components should never appear in server HTML

'use client' marks a bundle boundary for shipping JavaScript to the browser, not a render-location restriction; Next.js still pre-renders Client Components to HTML on the server for the initial response, then hydrates that HTML on the client to attach interactivity

Next.js caches a previous client render and reuses it as a placeholder until hydration completes

The HTML seen before hydration is generated by a service worker, not the server