What changed about route and request APIs in modern Next.js?

I await the value near the component or handler that owns the decision instead of passing an unresolved route object through the whole application. A dynamic segment still arrives as a broad string, string array, or optional value, so I validate identifiers, locales, pagination, and enum-like values at runtime before narrowing them. Page searchParams are appropriate for server rendering, while interactive client components can use useSearchParams. During an upgrade I use the official codemod, then review request-bound code rather than preserving synchronous compatibility patterns.