Splits mixed Server/Client pages into separate files with clean boundaries — extracting client logic into a `<DescriptiveName>Client.tsx` and rewriting `page.tsx` as a pure Server Component — and flags repeated JSX structures for extraction into shared typed components. Apply when working in a Next.js App Router project and you detect `export const metadata` alongside `"use client"`, hooks in a Server Component, a page file that has grown unwieldy (>200–300 LOC) with interactive logic, or the same layout block duplicated inline multiple times.