Show Chinese locale only when Chinese language signals are detected.

Hide the language switcher for English-only browsers; gate /zh via Accept-Language and a client cookie.

Co-authored-by: Cursor <cursoragent@cursor.com>

middleware.ts

@@ -1,7 +1,37 @@
 import createMiddleware from "next-intl/middleware";
+import { NextRequest, NextResponse } from "next/server";
 import { routing } from "./i18n/routing";
+import {
+  acceptLanguageHasChinese,
+  ZH_OK_COOKIE,
+} from "./lib/chinese-locale";
 
-export default createMiddleware(routing);
+const intlMiddleware = createMiddleware({
+  ...routing,
+  localeDetection: true,
+});
+
+function requestAllowsChinese(request: NextRequest): boolean {
+  if (acceptLanguageHasChinese(request.headers.get("accept-language"))) {
+    return true;
+  }
+  return request.cookies.get(ZH_OK_COOKIE)?.value === "1";
+}
+
+export default function middleware(request: NextRequest) {
+  const { pathname } = request.nextUrl;
+
+  // Shared /zh links: without Chinese signals → English only
+  if (pathname === "/zh" || pathname.startsWith("/zh/")) {
+    if (!requestAllowsChinese(request)) {
+      const url = request.nextUrl.clone();
+      url.pathname = pathname.replace(/^\/zh/, "/en") || "/en";
+      return NextResponse.redirect(url);
+    }
+  }
+
+  return intlMiddleware(request);
+}
 
 export const config = {
   matcher: ["/", "/(en|zh)/:path*", "/((?!api|_next|_vercel|.*\\..*).*)"],