Nextjs Ttfb Routing

Resolve locale from route params

• For localized trees such as app/[locale]/..., use params.locale as the source of truth.
• Move locale-aware providers into app/[locale]/layout.tsx.
• Use generateStaticParams() for known locales when appropriate.

Keep middleware narrow

• Limit proxy.ts or middleware to the smallest possible matcher.
• Do not inject locale headers into already localized routes just to support layout logic.
• Prefer redirect-only middleware for / or legacy non-localized entry points.

Gate private layouts on the server

• Prefer a server auth gate in app/(group)/layout.tsx for private sections.
• Redirect unauthorized users before rendering the route.
• Do not rely on a client-only ProtectedRoute to block the whole tree.

Render shell first, data second

• Render sidebar, header, titles, and section structure immediately.
• Use local skeletons per section instead of a full-page auth skeleton.
• Keep the route entry small and move interactive data-heavy logic into isolated client components.

Load Detailed Guidance Only When Needed

Read references/performance-ttfb-and-routing.md when you need:

• the rationale behind these rules
• Netlify-specific context
• a review checklist for layouts, middleware, auth, and i18n changes
• concrete do/don't guidance before implementing a refactor