Fix: Ensure 404 page always shows route suggestions

packages/fern-docs/bundle/src/app/[host]/[domain]/[lang]/dynamic/not-found.tsx

@@ -3,6 +3,7 @@ import "server-only";
 import NotFoundContent from "@/components/NotFoundContent";
 
 export const dynamic = "force-dynamic";
+export const runtime = "nodejs";
 
 export default async function NotFound() {
     return <NotFoundContent />;

packages/fern-docs/bundle/src/app/[host]/[domain]/[lang]/static/not-found.tsx

@@ -3,6 +3,7 @@ import "server-only";
 import NotFoundContent from "@/components/NotFoundContent";
 
 export const dynamic = "force-dynamic";
+export const runtime = "nodejs";
 
 export default async function NotFound() {
     return <NotFoundContent />;

packages/fern-docs/bundle/src/components/NotFoundContent/index.tsx

@@ -11,6 +11,53 @@ import { NotFound404Tracker } from "../analytics/NotFound404Tracker";
 import ReturnHomeButton from "../ReturnHomeButton";
 import { getRouteSuggestions, type RouteSuggestion } from "./get-route-suggestions";
 
+/**
+ * Generate fallback suggestions based on the requested path
+ * Returns parent paths as suggestions when server suggestions fail
+ */
+function generateFallbackSuggestions(requestedPath: string): RouteSuggestion[] {
+    if (!requestedPath || requestedPath === "/") {
+        return [];
+    }
+
+    const normalizedPath = requestedPath.replace(/^\/+|\/+$/g, "");
+    const segments = normalizedPath.split("/").filter((s) => s.length > 0);
+
+    const suggestions: RouteSuggestion[] = [];
+
+    for (let i = segments.length - 1; i > 0; i--) {
+        const parentPath = "/" + segments.slice(0, i).join("/");
+        const title = segments
+            .slice(0, i)
+            .map((s) => s.charAt(0).toUpperCase() + s.slice(1).replace(/-/g, " "))
+            .join(" › ");
+
+        suggestions.push({
+            slug: parentPath,
+            title: title,
+            href: parentPath,
+            score: 1 - (segments.length - i) * 0.2,
+            subtitle: "Parent section"
+        });
+
+        if (suggestions.length >= 3) {
+            break;
+        }
+    }
+
+    if (suggestions.length < 3) {
+        suggestions.push({
+            slug: "/",
+            title: "Home",
+            href: "/",
+            score: 0.1,
+            subtitle: "Return to homepage"
+        });
+    }
+
+    return suggestions;
+}
+
 export default function NotFoundContent() {
     const pathname = usePathname();
     const [suggestedRoutes, setSuggestedRoutes] = useState<RouteSuggestion[]>([]);
@@ -23,9 +70,17 @@ export default function NotFoundContent() {
             try {
                 setIsLoading(true);
                 const suggestions = await getRouteSuggestions(requestedPath);
-                setSuggestedRoutes(suggestions);
+
+                if (suggestions.length > 0) {
+                    setSuggestedRoutes(suggestions);
+                } else {
+                    const fallbackSuggestions = generateFallbackSuggestions(requestedPath);
+                    setSuggestedRoutes(fallbackSuggestions);
+                }
             } catch (error) {
                 console.error("[NotFoundContent] Error loading suggestions:", error);
+                const fallbackSuggestions = generateFallbackSuggestions(requestedPath);
+                setSuggestedRoutes(fallbackSuggestions);
             } finally {
                 setIsLoading(false);
             }