Redirect to space base path on fallback true

packages/gitbook/src/components/SitePage/SitePage.tsx

@@ -102,6 +102,9 @@ export async function generateSitePageMetadata(props: SitePageProps): Promise<Me
     });
 
     if (!pageTarget) {
+        if (context.isFallback) {
+            redirect(context.linker.toPathInSpace('/'));
+        }
         notFound();
     }
 
@@ -154,6 +157,10 @@ export async function getSitePageData(props: SitePageProps) {
             // before trying to resolve the page again
             redirect(context.linker.toPathInSpace(pathname));
         } else {
+            // If the page is not found and we are in fallback mode, return a redirect to the basepath
+            if (context.isFallback) {
+                redirect(context.linker.toPathInSpace('/'));
+            }
             notFound();
         }
     } else if (getPagePath(context.revision.pages, pageTarget.page) !== rawPathname) {

packages/gitbook/src/lib/context.ts

@@ -50,6 +50,13 @@ export type SiteURLData = Pick<
      * Identifier used for image resizing.
      */
     imagesContextId: string;
+
+    /**
+     * Whether this request is a fallback rendering.
+     * We use this when switching variant as we don't know if the page exists in the other variant.
+     * By knowing it's a fallback, we can redirect to the space base path instead of returning a 404.
+     */
+    isFallback?: boolean;
 };
 
 /**
@@ -127,6 +134,9 @@ export type GitBookSiteContext = GitBookSpaceContext & {
 
     /** Context ID used by adaptive content. It represents an unique identifier for the authentication context */
     contextId?: string;
+
+    /** Whether this request is a fallback rendering. */
+    isFallback: boolean;
 };
 
 /**
@@ -205,6 +215,7 @@ export async function fetchSiteContextByURLLookup(
         changeRequest: data.changeRequest,
         revision: data.revision,
         contextId: data.contextId,
+        isFallback: data.isFallback ?? false,
     });
 }
 
@@ -223,6 +234,7 @@ export async function fetchSiteContextByIds(
         changeRequest: string | undefined;
         revision: string | undefined;
         contextId?: string;
+        isFallback: boolean;
     }
 ): Promise<GitBookSiteContext> {
     const { dataFetcher } = baseContext;
@@ -321,6 +333,7 @@ export async function fetchSiteContextByIds(
         sections,
         scripts,
         contextId: ids.contextId,
+        isFallback: ids.isFallback,
     };
 }
 

packages/gitbook/src/middleware.ts

@@ -298,6 +298,7 @@ async function serveSiteRoutes(requestURL: URL, request: NextRequest) {
             apiToken: siteURLData.apiToken,
             imagesContextId: imagesContextId,
             contextId: siteURLData.contextId,
+            isFallback: requestURL.searchParams.get('fallback') === 'true' ? true : undefined,
         };
 
         const requestHeaders = new Headers(request.headers);
@@ -382,7 +383,11 @@ async function serveSiteRoutes(requestURL: URL, request: NextRequest) {
         ].join('/');
 
         const rewrittenURL = new URL(`/${route}`, request.nextUrl.toString());
-        rewrittenURL.search = request.nextUrl.search; // Preserve the original search params
+        // Preserve the original search params but remove fallback=true if present
+        rewrittenURL.search = request.nextUrl.search;
+        if (rewrittenURL.searchParams.has('fallback')) {
+            rewrittenURL.searchParams.delete('fallback');
+        }
 
         const response = NextResponse.rewrite(rewrittenURL, {
             request: {