fix(nextjs): Use nextjs fetcher to identify internal page navigation

.changeset/late-falcons-sell.md

@@ -0,0 +1,5 @@
+---
+'@clerk/nextjs': patch
+---
+
+Enhance page detection by utilizing the patched fetch from nextjs.

integration/tests/protect.test.ts

@@ -67,16 +67,13 @@ testAgainstRunningApps({ withEnv: [appConfigs.envs.withCustomRoles] })('authoriz
   test('Protect in RSCs and RCCs as `signed-out user`', async ({ page, context }) => {
     const u = createTestUtils({ app, page, context });
 
-    // Do not run this part for nextjs v14, the flow is broken in 14.2.3 because vercel removed a header that our page detection logic depends on
-    if (!u.nexJsVersion.startsWith('14')) {
-      /**
-       * Soft navigations
-       */
-      await u.page.goToRelative('/');
-      await page.getByText('Page Protected').click();
-      await page.waitForURL('**/sign-in?**');
-      await u.po.signIn.waitForMounted();
-    }
+    /**
+     * Soft navigations
+     */
+    await u.page.goToRelative('/');
+    await page.getByText('Page Protected').click();
+    await page.waitForURL('**/sign-in?**');
+    await u.po.signIn.waitForMounted();
 
     /**
      * Hard navigations

packages/nextjs/src/server/nextFetcher.ts

@@ -0,0 +1,22 @@
+type Fetcher = typeof globalThis.fetch;
+
+/**
+ * Based on nextjs internal implementation https://github.com/vercel/next.js/blob/6185444e0a944a82e7719ac37dad8becfed86acd/packages/next/src/server/lib/patch-fetch.ts#L23
+ */
+type NextFetcher = Fetcher & {
+  readonly __nextPatched: true;
+  readonly __nextGetStaticStore: () => { getStore: () => StaticGenerationAsyncStorage };
+};
+
+/**
+ * Full type can be found https://github.com/vercel/next.js/blob/6185444e0a944a82e7719ac37dad8becfed86acd/packages/next/src/client/components/static-generation-async-storage.external.ts#L4
+ */
+interface StaticGenerationAsyncStorage {
+  readonly pagePath?: string;
+}
+
+function isNextFetcher(fetch: Fetcher | NextFetcher): fetch is NextFetcher {
+  return '__nextPatched' in fetch && fetch.__nextPatched === true;
+}
+
+export { isNextFetcher };

packages/nextjs/src/server/protect.ts

@@ -6,6 +6,7 @@ import type {
 } from '@clerk/types';
 
 import { constants as nextConstants } from '../constants';
+import { isNextFetcher } from './nextFetcher';
 
 type AuthProtectOptions = { unauthorizedUrl?: string; unauthenticatedUrl?: string };
 
@@ -121,12 +122,24 @@ const isPageRequest = (req: Request): boolean => {
   return (
     req.headers.get(constants.Headers.SecFetchDest) === 'document' ||
     req.headers.get(constants.Headers.Accept)?.includes('text/html') ||
-    (!!req.headers.get(nextConstants.Headers.NextUrl) && !isServerActionRequest(req)) ||
-    !!req.headers.get(nextConstants.Headers.NextjsData)
+    isAppRouterInternalNavigation(req) ||
+    isPagesRouterInternalNavigation(req)
   );
 };
 
-// In case we want to handle router handlers and server actions differently in the future
-// const isRouteHandler = (req: Request) => {
-//   return !isPageRequest(req) && !isServerAction(req);
+const isAppRouterInternalNavigation = (req: Request) =>
+  (!!req.headers.get(nextConstants.Headers.NextUrl) && !isServerActionRequest(req)) || isPagePathAvailable();
+
+const isPagePathAvailable = () => {
+  const __fetch = globalThis.fetch;
+  return Boolean(isNextFetcher(__fetch) ? __fetch.__nextGetStaticStore().getStore().pagePath : false);
+};
+
+const isPagesRouterInternalNavigation = (req: Request) => !!req.headers.get(nextConstants.Headers.NextjsData);
+
+// /**
+//  * In case we want to handle router handlers and server actions differently in the future
+//  */
+// const isApiRouteRequest = (req: Request) => {
+//   return !isPageRequest(req) && !isServerActionRequest(req);
 // };