BK202503 Next.js App Router review
Review changed App Router files only. Resolve the Next.js version from package.json when version semantics matter.
Check client components importing server-only code or secrets, hooks in server components, unintended fetch caching or dynamic rendering, async params and searchParams in Next 15+, route handlers returning invalid responses or missing caching policy, Edge-incompatible middleware APIs, and environment variables exposed to client code.
Report severity, file and line, runtime or data-exposure impact, and a concrete fix. Do not modify code.