cloudflare · james-elicx · Sep 15, 2026
diff --git a/packages/vinext/src/server/app-metadata-tracing.ts b/packages/vinext/src/server/app-metadata-tracing.ts
@@ -0,0 +1,22 @@
+import { frameworkTracer } from "./tracer.js";
+
+type AppMetadataModuleType = "forbidden" | "layout" | "not-found" | "page" | "unauthorized";
+
+export function createAppMetadataModuleRoute(
+  routeSegments: readonly string[],
+  moduleType: AppMetadataModuleType,
+): string {
+  return `/${[...routeSegments.filter((segment) => !segment.startsWith("@")), moduleType].join("/")}`;
+}
+
+export function traceGenerateMetadata<T>(moduleRoute: string, callback: () => T): T {
+  return frameworkTracer.trace(createGenerateMetadataSpanDescriptor(moduleRoute), callback);
+}
+
+export function createGenerateMetadataSpanDescriptor(moduleRoute: string) {
+  return {
+    attributes: { "next.page": moduleRoute },
+    name: `generateMetadata ${moduleRoute}`,
+    type: "ResolveMetadata.generateMetadata",
+  } as const;
+}
diff --git a/packages/vinext/src/server/app-page-boundary-render.ts b/packages/vinext/src/server/app-page-boundary-render.ts
@@ -625,6 +625,11 @@ export async function renderAppPageHttpAccessFallback<TModule extends AppPageMod
             ...(intercept?.interceptNotFound
               ? {
                   notFoundModule: intercept.interceptNotFound,
+                  notFoundModuleRouteSegments: (
+                    intercept.interceptNotFoundBranchSegments ??
+                    intercept.interceptSourcePageSegments ??
+                    fallbackRouteSegments
+                  ).slice(0, intercept.interceptNotFoundTreePosition ?? 0),
                   notFoundParams: resolveAppPageBranchParams(
                     intercept.interceptNotFoundBranchSegments ??
                       intercept.interceptBranchSegments ??
@@ -640,7 +645,14 @@ export async function renderAppPageHttpAccessFallback<TModule extends AppPageMod
       const fallbackHeadOptions = {
         boundaryModule,
         boundaryParams,
+        boundaryRouteSegments: fallbackRouteSegments.slice(0, boundaryTreePosition ?? 0),
         branchNotFoundConventions: options.statusCode === 404,
+        errorConvention:
+          options.statusCode === 403
+            ? ("forbidden" as const)
+            : options.statusCode === 401
+              ? ("unauthorized" as const)
+              : ("not-found" as const),
         layoutModules,
         layoutTreePositions: resolveHttpAccessFallbackHeadLayoutTreePositions(
           options.route,

diff --git a/packages/vinext/src/server/app-page-dispatch.ts b/packages/vinext/src/server/app-page-dispatch.ts
@@ -1132,23 +1132,12 @@ async function dispatchAppPageInner<TRoute extends AppPageDispatchRoute>(
     discardAppPageRenderState();
   }
 
-  const pageBuildResult = await buildCurrentPageElement();
-  if (pageBuildResult.response) {
-    return pageBuildResult.response;
-  }
-
   const navigationParams = resolveAppPageNavigationParams(
     route,
     options.params,
     options.cleanPathname,
     interceptResult.interceptOpts,
   );
-  options.setNavigationContext({
-    pathname: options.displayPathname ?? options.cleanPathname,
-    searchParams: pageSearchParams,
-    params: navigationParams,
-  });
-
   const layoutClassifications = getEffectiveLayoutClassifications(
     route,
     options.debugClassification,
@@ -1174,7 +1163,16 @@ async function dispatchAppPageInner<TRoute extends AppPageDispatchRoute>(
     createRscOnErrorHandler(pathname, routePath, overrides) {
       return options.createRscOnErrorHandler(pathname, routePath, overrides);
     },
-    element: pageBuildResult.element,
+    async prepareElement() {
+      const pageBuildResult = await buildCurrentPageElement();
+      if (pageBuildResult.response) return { response: pageBuildResult.response };
+      options.setNavigationContext({
+        pathname: options.displayPathname ?? options.cleanPathname,
+        searchParams: pageSearchParams,
+        params: navigationParams,
+      });
+      return { element: pageBuildResult.element };
+    },
     clientReuseManifest: options.clientReuseManifest,
     getDraftModeCookieHeader,
     getFontLinks: options.getFontLinks,

diff --git a/packages/vinext/src/server/app-page-element-builder.ts b/packages/vinext/src/server/app-page-element-builder.ts
@@ -338,6 +338,12 @@ export async function buildPageElements<
         ...(opts?.interceptNotFound
           ? {
               notFoundModule: opts.interceptNotFound,
+              notFoundModuleRouteSegments: (
+                opts.interceptNotFoundBranchSegments ??
+                opts.interceptSourcePageSegments ??
+                route.routeSegments ??
+                []
+              ).slice(0, opts.interceptNotFoundTreePosition ?? 0),
               notFoundParams: resolveAppPageBranchParams(
                 opts.interceptNotFoundBranchSegments ??
                   opts.interceptBranchSegments ??
@@ -426,6 +432,8 @@ export async function buildPageElements<
     return {
       boundaryModule,
       boundaryParams,
+      boundaryRouteSegments: (route.routeSegments ?? []).slice(0, boundaryTreePosition ?? 0),
+      errorConvention: "not-found" as const,
       layoutModules: route.layouts,
       layoutTreePositions: route.layoutTreePositions,
       parallelBranches: activeParallelRouteHeadInputs,

diff --git a/packages/vinext/src/server/app-page-head.ts b/packages/vinext/src/server/app-page-head.ts
@@ -13,6 +13,7 @@ import { runWithFetchDedupe } from "vinext/shims/fetch-cache";
 import type { ThenableParamsObserver } from "vinext/shims/thenable-params";
 import type { AppPageParams } from "./app-page-boundary.js";
 import { tagAppPageMetadataError } from "./app-page-execution.js";
+import { createAppMetadataModuleRoute, traceGenerateMetadata } from "./app-metadata-tracing.js";
 import { resolveAppPageBranchParams, resolveAppPageSegmentParams } from "./app-page-params.js";
 import type { MetadataFileRoute } from "./metadata-routes.js";
 
@@ -29,10 +30,13 @@ import type { MetadataFileRoute } from "./metadata-routes.js";
  * and Next.js test/e2e/app-dir/metadata-streaming.
  */
 async function resolveModuleMetadata(
+  moduleRoute: string,
   ...args: Parameters<typeof _resolveModuleMetadata>
 ): Promise<Metadata | null> {
   try {
-    return await _resolveModuleMetadata(...args);
+    return await (typeof args[0].generateMetadata === "function"
+      ? traceGenerateMetadata(moduleRoute, () => _resolveModuleMetadata(...args))
+      : _resolveModuleMetadata(...args));
   } catch (error) {
     throw tagAppPageMetadataError(error);
   }
@@ -54,6 +58,7 @@ export type OrderedAppPageMetadataSource<TModule extends AppPageHeadModule = App
   /** Preserve an empty result as the most specific file-metadata source. */
   includeWhenEmpty?: boolean;
   module: TModule;
+  moduleRoute: string;
   params: AppPageParams;
   routeSegments: readonly string[];
   searchParams?: AppPageSearchParams;
@@ -70,6 +75,8 @@ export type AppPageHeadParallelRoute<TModule extends AppPageHeadModule = AppPage
   layoutModule?: TModule | null;
   layoutModules?: readonly (TModule | null | undefined)[] | null;
   layoutTreePositions?: readonly number[] | null;
+  moduleRoutePrefixSegments?: readonly string[] | null;
+  moduleRouteSegments?: readonly string[] | null;
   pageModule?: TModule | null;
   params?: AppPageParams | null;
   routeSegments?: readonly string[] | null;
@@ -78,6 +85,7 @@ export type AppPageHeadParallelRoute<TModule extends AppPageHeadModule = AppPage
 export type ActiveParallelRouteHeadInput<TModule extends AppPageHeadModule = AppPageHeadModule> = {
   head: AppPageHeadParallelRoute<TModule>;
   notFoundModule?: TModule | null;
+  notFoundModuleRouteSegments?: readonly string[] | null;
   notFoundParams?: AppPageParams | null;
   ownerTreePosition: number;
 };
@@ -184,6 +192,7 @@ export function resolveActiveParallelRouteHeadInputs<TModule extends AppPageHead
 ): ActiveParallelRouteHeadInput<TModule>[] {
   const inputs = Object.entries(options.slots ?? {}).map(([slotKey, slot]) => {
     const ownerTreePosition = options.layoutTreePositions?.[slot.layoutIndex ?? 0] ?? 0;
+    const ownerRouteSegments = options.routeSegments.slice(0, ownerTreePosition);
     const ownerParams = resolveAppPageSegmentParams(
       options.routeSegments,
       ownerTreePosition,
@@ -209,6 +218,16 @@ export function resolveActiveParallelRouteHeadInputs<TModule extends AppPageHead
       const inheritedSlotNotFound =
         slot.notFoundTreePosition === 0 ? (slot.notFound ?? null) : null;
       const interceptNotFound = options.interceptNotFound ?? inheritedSlotNotFound;
+      const interceptRouteSegments = options.interceptSourcePageSegments ?? options.routeSegments;
+      const interceptNotFoundRouteSegments = options.interceptNotFound
+        ? (options.interceptNotFoundBranchSegments ?? interceptRouteSegments).slice(
+            0,
+            options.interceptNotFoundTreePosition ?? 0,
+          )
+        : [
+            ...ownerRouteSegments,
+            ...(slot.routeSegments ?? []).slice(0, slot.notFoundTreePosition ?? 0),
+          ];
       const interceptNotFoundParams = interceptNotFound
         ? {
             ...ownerParams,
@@ -246,15 +265,21 @@ export function resolveActiveParallelRouteHeadInputs<TModule extends AppPageHead
           ],
           pageModule: options.interceptPage,
           params: options.interceptParams ?? options.params,
-          routeSegments: options.interceptSourcePageSegments ?? options.routeSegments,
+          routeSegments: interceptRouteSegments,
         },
         ...(interceptNotFound
-          ? { notFoundModule: interceptNotFound, notFoundParams: interceptNotFoundParams }
+          ? {
+              notFoundModule: interceptNotFound,
+              notFoundModuleRouteSegments: interceptNotFoundRouteSegments,
+              notFoundParams: interceptNotFoundParams,
+            }
           : {}),
         ownerTreePosition,
       };
     }
 
+    const slotRouteSegments = slot.routeSegments ?? options.routeSegments;
+    const moduleRouteSegments = slot.routeSegments ?? [];
     return {
       head: {
         layoutModules: [slot.layout, ...(slot.configLayouts ?? [])].filter(isPresent),
@@ -275,9 +300,20 @@ export function resolveActiveParallelRouteHeadInputs<TModule extends AppPageHead
         ],
         pageModule: slot.page,
         params: slotParams,
-        routeSegments: slot.routeSegments ?? options.routeSegments,
+        ...(ownerRouteSegments.length > 0 ? { moduleRoutePrefixSegments: ownerRouteSegments } : {}),
+        ...(slot.routeSegments ? {} : { moduleRouteSegments }),
+        routeSegments: slotRouteSegments,
       },
-      ...(slot.notFound ? { notFoundModule: slot.notFound, notFoundParams } : {}),
+      ...(slot.notFound
+        ? {
+            notFoundModule: slot.notFound,
+            notFoundModuleRouteSegments: [
+              ...ownerRouteSegments,
+              ...moduleRouteSegments.slice(0, slot.notFoundTreePosition ?? 0),
+            ],
+            notFoundParams,
+          }
+        : {}),
       ownerTreePosition,
     };
   });
@@ -414,6 +450,7 @@ async function resolveLayoutMetadata<TModule extends AppPageHeadModule>(
       params,
     );
     const metadataPromise = resolveModuleMetadata(
+      createAppMetadataModuleRoute(routeSegments.slice(0, layoutInput.treePosition), "layout"),
       layoutInput.module,
       layoutParams,
       undefined,
@@ -505,6 +542,8 @@ async function resolveParallelRouteMetadata<TModule extends AppPageHeadModule>(
 ): Promise<ResolvedParallelRouteMetadata> {
   const params = parallelRoute.params ?? fallbackParams;
   const routeSegments = parallelRoute.routeSegments ?? fallbackRouteSegments;
+  const moduleRoutePrefixSegments = parallelRoute.moduleRoutePrefixSegments ?? [];
+  const moduleRouteSegments = parallelRoute.moduleRouteSegments ?? routeSegments;
   const metadataResults: (Metadata | null)[] = [];
   const metadataSources: AppPageHeadSource[] = [];
   let accumulatedMetadata = parent;
@@ -517,6 +556,13 @@ async function resolveParallelRouteMetadata<TModule extends AppPageHeadModule>(
       layoutParams[index] ??
       resolveParallelLayoutParams(routeSegments, layoutTreePositions[index] ?? 0, params);
     const layoutMetadata = await resolveModuleMetadata(
+      createAppMetadataModuleRoute(
+        [
+          ...moduleRoutePrefixSegments,
+          ...moduleRouteSegments.slice(0, layoutTreePositions[index] ?? 0),
+        ],
+        "layout",
+      ),
       layoutModule,
       currentLayoutParams,
       undefined,
@@ -537,6 +583,7 @@ async function resolveParallelRouteMetadata<TModule extends AppPageHeadModule>(
 
   if (parallelRoute.pageModule) {
     const pageMetadata = await resolveModuleMetadata(
+      createAppMetadataModuleRoute([...moduleRoutePrefixSegments, ...moduleRouteSegments], "page"),
       parallelRoute.pageModule,
       params,
       pageSearchParams,
@@ -622,6 +669,7 @@ export function resolveOrderedAppPageMetadata<TModule extends AppPageHeadModule>
         entries.length > 0 ? mergeMetadataEntries(entries) : {},
       );
       const metadataPromise = resolveModuleMetadata(
+        source.moduleRoute,
         source.module,
         source.params,
         source.searchParams,
@@ -704,6 +752,7 @@ function prepareAppPageHeadInner<TModule extends AppPageHeadModule>(
   void pageParentPromise.catch(() => null);
   const pageMetadataPromise = options.pageModule
     ? resolveModuleMetadata(
+        createAppMetadataModuleRoute(routeSegments, "page"),
         options.pageModule,
         options.params,
         pageSearchParams,

diff --git a/packages/vinext/src/server/app-page-http-access-fallback-metadata.ts b/packages/vinext/src/server/app-page-http-access-fallback-metadata.ts
@@ -12,15 +12,18 @@ import {
   type ApplyAppPageFileBasedMetadata,
   type OrderedAppPageMetadataSource,
 } from "./app-page-head.js";
+import { createAppMetadataModuleRoute } from "./app-metadata-tracing.js";
 import { resolveAppPageBranchParams, resolveAppPageSegmentParams } from "./app-page-params.js";
 import type { MetadataFileRoute } from "./metadata-routes.js";
 
 type HttpAccessFallbackMetadataPlanOptions<TModule extends AppPageHeadModule = AppPageHeadModule> =
   {
     boundaryModule?: TModule | null;
     boundaryParams: AppPageParams;
+    boundaryRouteSegments?: readonly string[] | null;
     /** Whether active branches may replace the fallback with their local not-found convention. */
     branchNotFoundConventions?: boolean;
+    errorConvention: "forbidden" | "not-found" | "unauthorized";
     layoutModules: readonly (TModule | null | undefined)[];
     layoutTreePositions?: readonly number[] | null;
     parallelBranches?: readonly ActiveParallelRouteHeadInput<TModule>[] | null;
@@ -70,6 +73,10 @@ function createHttpAccessFallbackPlan<TModule extends AppPageHeadModule>(
       source: {
         includeWhenEmpty: true,
         module: layoutModule,
+        moduleRoute: createAppMetadataModuleRoute(
+          routeSegments.slice(0, treePosition),
+          options.errorConvention,
+        ),
         params: resolveAppPageSegmentParams(routeSegments, treePosition, options.params),
         routeSegments: routeSegments.slice(0, treePosition),
       },
@@ -78,7 +85,7 @@ function createHttpAccessFallbackPlan<TModule extends AppPageHeadModule>(
 
   let activeBoundaryModule = options.boundaryModule;
   let activeBoundaryParams = options.boundaryParams;
-  let activeBoundaryRouteSegments = routeSegments;
+  let activeBoundaryRouteSegments = options.boundaryRouteSegments ?? [];
   const appendFallbackLeaf = () => {
     if (fallbackLeafMode === "final") {
       plan.push({ kind: "fallback-leaf" });
@@ -90,6 +97,10 @@ function createHttpAccessFallbackPlan<TModule extends AppPageHeadModule>(
       source: {
         includeWhenEmpty: true,
         module: activeBoundaryModule,
+        moduleRoute: createAppMetadataModuleRoute(
+          activeBoundaryRouteSegments,
+          options.errorConvention,
+        ),
         params: activeBoundaryParams,
         routeSegments: activeBoundaryRouteSegments,
       },
@@ -111,6 +122,8 @@ function createHttpAccessFallbackPlan<TModule extends AppPageHeadModule>(
     const parallelRoute = branch.head;
     const parallelParams = parallelRoute.params ?? options.params;
     const parallelRouteSegments = parallelRoute.routeSegments ?? routeSegments;
+    const parallelModuleRoutePrefix = parallelRoute.moduleRoutePrefixSegments ?? [];
+    const parallelModuleRouteSegments = parallelRoute.moduleRouteSegments ?? parallelRouteSegments;
     const layoutModules = [
       ...(parallelRoute.layoutModules ?? []),
       parallelRoute.layoutModule,
@@ -124,6 +137,13 @@ function createHttpAccessFallbackPlan<TModule extends AppPageHeadModule>(
         source: {
           includeWhenEmpty: true,
           module: layoutModule,
+          moduleRoute: createAppMetadataModuleRoute(
+            [
+              ...parallelModuleRoutePrefix,
+              ...parallelModuleRouteSegments.slice(0, layoutTreePositions[index] ?? 0),
+            ],
+            options.errorConvention,
+          ),
           params:
             layoutParams[index] ??
             resolveAppPageBranchParams(
@@ -138,7 +158,10 @@ function createHttpAccessFallbackPlan<TModule extends AppPageHeadModule>(
     if (options.branchNotFoundConventions !== false && branch.notFoundModule) {
       activeBoundaryModule = branch.notFoundModule;
       activeBoundaryParams = branch.notFoundParams ?? parallelParams;
-      activeBoundaryRouteSegments = parallelRouteSegments;
+      activeBoundaryRouteSegments = branch.notFoundModuleRouteSegments ?? [
+        ...parallelModuleRoutePrefix,
+        ...parallelModuleRouteSegments,
+      ];
     }
     appendFallbackLeaf();
   }
@@ -150,6 +173,10 @@ function createHttpAccessFallbackPlan<TModule extends AppPageHeadModule>(
       {
         includeWhenEmpty: true,
         module: activeBoundaryModule,
+        moduleRoute: createAppMetadataModuleRoute(
+          activeBoundaryRouteSegments,
+          options.errorConvention,
+        ),
         params: activeBoundaryParams,
         routeSegments: activeBoundaryRouteSegments,
       },