fix(server): render progressive action not-found HTML

packages/vinext/src/entries/app-rsc-entry.ts

@@ -447,6 +447,8 @@ export default __createAppRscHandler({
   dispatchMatchedPage({
     cleanPathname,
     formState,
+    actionError,
+    actionFailed,
     handlerStart,
     interceptionContext,
     isProgressiveActionRender,
@@ -513,6 +515,8 @@ export default __createAppRscHandler({
       interceptionContext,
       expireSeconds: __expireTime,
       formState,
+      actionError,
+      actionFailed,
       isProgressiveActionRender,
       isProduction: process.env.NODE_ENV === "production",
       isRscRequest,

packages/vinext/src/server/app-page-dispatch.ts

@@ -157,6 +157,8 @@ type DispatchAppPageOptions<TRoute extends AppPageDispatchRoute> = {
   fetchCache?: FetchCacheMode | null;
   findIntercept: (pathname: string) => AppPageDispatchIntercept | null;
   formState?: ReactFormState | null;
+  actionError?: unknown;
+  actionFailed?: boolean;
   generateStaticParams?: ValidateAppPageDynamicParamsOptions["generateStaticParams"];
   getFontLinks: () => string[];
   getFontPreloads: () => AppPageFontPreload[];
@@ -583,6 +585,9 @@ async function dispatchAppPageInner<TRoute extends AppPageDispatchRoute>(
 
   const pageBuildResult = await buildAppPageElement({
     buildPageElement() {
+      if (options.actionFailed) {
+        throw options.actionError;
+      }
       return options.buildPageElement(
         route,
         options.params,

packages/vinext/src/server/app-rsc-handler.ts

@@ -85,6 +85,8 @@ type AppRscRouteMatch<TRoute> = {
 type DispatchMatchedPageOptions<TRoute> = {
   cleanPathname: string;
   formState: ReactFormState | null;
+  actionError?: unknown;
+  actionFailed?: boolean;
   handlerStart: number;
   interceptionContext: string | null;
   isProgressiveActionRender: boolean;
@@ -116,6 +118,18 @@ type HandleProgressiveActionRequestOptions = {
   request: Request;
 };
 
+type ProgressiveActionFormStateResult =
+  | {
+      formState: ReactFormState | null;
+      kind: "form-state";
+    }
+  | {
+      actionError: unknown;
+      actionFailed: true;
+      formState: null;
+      kind: "form-state";
+    };
+
 type HandleServerActionRequestOptions = {
   actionId: string | null;
   cleanPathname: string;
@@ -167,7 +181,7 @@ type CreateAppRscHandlerOptions<TRoute extends AppRscHandlerRoute> = {
   ensureInstrumentation?: () => Promise<void>;
   handleProgressiveActionRequest: (
     options: HandleProgressiveActionRequestOptions,
-  ) => Promise<Response | { formState: ReactFormState | null; kind: "form-state" } | null>;
+  ) => Promise<Response | ProgressiveActionFormStateResult | null>;
   handleServerActionRequest: (
     options: HandleServerActionRequestOptions,
   ) => Promise<Response | null>;
@@ -420,6 +434,12 @@ async function handleAppRscRequest<TRoute extends AppRscHandlerRoute>(
   if (progressiveActionResult instanceof Response) return progressiveActionResult;
   const isProgressiveActionRender = progressiveActionResult?.kind === "form-state";
   const formState = isProgressiveActionRender ? progressiveActionResult.formState : null;
+  const failedProgressiveActionResult =
+    isProgressiveActionRender && "actionFailed" in progressiveActionResult
+      ? progressiveActionResult
+      : null;
+  const actionFailed = failedProgressiveActionResult !== null;
+  const actionError = failedProgressiveActionResult?.actionError;
 
   const serverActionResponse = await options.handleServerActionRequest({
     actionId,
@@ -521,6 +541,8 @@ async function handleAppRscRequest<TRoute extends AppRscHandlerRoute>(
   return options.dispatchMatchedPage({
     cleanPathname,
     formState,
+    actionError,
+    actionFailed,
     handlerStart,
     interceptionContext: interceptionContextHeader,
     isProgressiveActionRender,

packages/vinext/src/server/app-server-action-execution.ts

@@ -73,10 +73,17 @@ type AppServerActionRoute = {
   pattern: string;
 };
 
-type ProgressiveServerActionResult = {
-  formState: ReactFormState | null;
-  kind: "form-state";
-};
+type ProgressiveServerActionResult =
+  | {
+      formState: ReactFormState | null;
+      kind: "form-state";
+    }
+  | {
+      actionError: unknown;
+      actionFailed: true;
+      formState: null;
+      kind: "form-state";
+    };
 
 type AppServerActionMatch<TRoute extends AppServerActionRoute> = {
   params: AppPageParams;
@@ -198,16 +205,6 @@ export type HandleServerActionRscRequestOptions<
   toInterceptOpts: (intercept: AppServerActionIntercept<TPage>) => TInterceptOpts;
 };
 
-type ActionControlResponse =
-  | {
-      kind: "redirect";
-      url: string;
-    }
-  | {
-      kind: "status";
-      statusCode: number;
-    };
-
 /**
  * Matches Next.js' server action argument cap to prevent stack overflow in
  * Function.prototype.apply when decoding hostile action payloads.
@@ -297,33 +294,6 @@ export async function readActionFormDataWithLimit(
   }).formData();
 }
 
-function getActionControlResponse(error: unknown): ActionControlResponse | null {
-  const digest = getNextErrorDigest(error);
-  if (!digest) return null;
-
-  const redirect = parseNextRedirectDigest(digest);
-  if (redirect) {
-    return {
-      kind: "redirect",
-      url: redirect.url,
-    };
-  }
-
-  const httpError = parseNextHttpErrorDigest(digest);
-  if (httpError) {
-    if (!Number.isInteger(httpError.status)) {
-      return null;
-    }
-
-    return {
-      kind: "status",
-      statusCode: httpError.status,
-    };
-  }
-
-  return null;
-}
-
 function getActionRedirect(error: unknown): AppServerActionRedirect | null {
   const digest = getNextErrorDigest(error);
   if (!digest) return null;
@@ -449,22 +419,43 @@ export async function handleProgressiveServerActionRequest(
       return null;
     }
 
-    let actionControlResponse: ActionControlResponse | null = null;
+    let actionRedirect: AppServerActionRedirect | null = null;
+    let actionError: unknown = undefined;
+    let actionFailed = false;
     let actionResult: unknown;
     const previousHeadersPhase = options.setHeadersAccessPhase("action");
     try {
       actionResult = await action();
     } catch (error) {
-      actionControlResponse = getActionControlResponse(error);
-      if (!actionControlResponse) {
-        throw error;
+      actionRedirect = getActionRedirect(error);
+      if (!actionRedirect) {
+        actionError = error;
+        actionFailed = true;
+        const isControlFlow =
+          getActionHttpFallbackStatus(error) !== null || isServerActionNotFoundError(error, null);
+        if (!isControlFlow) {
+          console.error("[vinext] Server action error:", error);
+          options.reportRequestError(
+            normalizeError(error),
+            {
+              path: options.cleanPathname,
+              method: options.request.method,
+              headers: Object.fromEntries(options.request.headers.entries()),
+            },
+            { routerKind: "App Router", routePath: options.cleanPathname, routeType: "action" },
+          );
+        }
       }
     } finally {
       options.setHeadersAccessPhase(previousHeadersPhase);
     }
 
-    if (!actionControlResponse) {
+    if (!actionRedirect) {
       getAndClearActionRevalidationKind();
+      if (actionFailed) {
+        return { kind: "form-state", formState: null, actionError, actionFailed };
+      }
+
       const formState = await options.decodeFormState(actionResult, body);
       return { kind: "form-state", formState: formState ?? null };
     }
@@ -477,9 +468,7 @@ export async function handleProgressiveServerActionRequest(
     options.clearRequestContext();
 
     const headers = new Headers();
-    if (actionControlResponse.kind === "redirect") {
-      headers.set("Location", new URL(actionControlResponse.url, options.request.url).toString());
-    }
+    headers.set("Location", new URL(actionRedirect.url, options.request.url).toString());
     mergeMiddlewareResponseHeaders(headers, options.middlewareHeaders);
     for (const cookie of actionPendingCookies) {
       headers.append("Set-Cookie", cookie);
@@ -490,7 +479,7 @@ export async function handleProgressiveServerActionRequest(
     setActionRevalidatedHeader(headers, actionRevalidationKind);
 
     return new Response(null, {
-      status: actionControlResponse.kind === "redirect" ? 303 : actionControlResponse.statusCode,
+      status: 303,
       headers,
     });
   } catch (error) {
@@ -503,10 +492,7 @@ export async function handleProgressiveServerActionRequest(
 
     getAndClearActionRevalidationKind();
     options.getAndClearPendingCookies();
-    // Next.js rethrows generic MPA action errors into its page render path.
-    // vinext does not yet implement that form-state render path, so unexpected
-    // action failures remain request failures here.
-    console.error("[vinext] Server action error:", error);
+    console.error("[vinext] Server action payload parsing error:", error);
     options.reportRequestError(
       normalizeError(error),
       {
@@ -520,7 +506,7 @@ export async function handleProgressiveServerActionRequest(
     return internalServerErrorResponse(
       process.env.NODE_ENV === "production"
         ? undefined
-        : "Server action failed: " + getServerActionFailureMessage(error),
+        : "Server action parsing failed: " + getServerActionFailureMessage(error),
     );
   }
 }

tests/app-page-dispatch.test.ts

@@ -74,6 +74,8 @@ function createDispatchOptions(
     clearRequestContext?: DispatchOptions["clearRequestContext"];
     generateStaticParams?: DispatchOptions["generateStaticParams"];
     formState?: DispatchOptions["formState"];
+    actionError?: DispatchOptions["actionError"];
+    actionFailed?: DispatchOptions["actionFailed"];
     isProgressiveActionRender?: DispatchOptions["isProgressiveActionRender"];
     isProduction?: boolean;
     isRscRequest?: boolean;
@@ -126,6 +128,8 @@ function createDispatchOptions(
     hasPageModule: true,
     handlerStart: 10,
     formState: overrides.formState,
+    actionError: overrides.actionError,
+    actionFailed: overrides.actionFailed,
     interceptionContext: null,
     isProgressiveActionRender: overrides.isProgressiveActionRender,
     isProduction: overrides.isProduction ?? false,
@@ -272,6 +276,31 @@ describe("app page dispatch", () => {
     await expect(response.text()).resolves.toBe("<html>page</html>");
   });
 
+  it("renders not-found HTML when a progressive action calls notFound()", async () => {
+    const buildPageElement = vi.fn(async () => React.createElement("main", null, "page"));
+    const renderHttpAccessFallbackPage = vi.fn(
+      async () => new Response("<html>not found</html>", { status: 404 }),
+    );
+    const { options } = createDispatchOptions({
+      actionError: { digest: "NEXT_HTTP_ERROR_FALLBACK;404" },
+      actionFailed: true,
+      buildPageElement,
+      isProgressiveActionRender: true,
+    });
+    options.renderHttpAccessFallbackPage = renderHttpAccessFallbackPage;
+
+    const response = await dispatchAppPage(options);
+
+    expect(response.status).toBe(404);
+    await expect(response.text()).resolves.toBe("<html>not found</html>");
+    expect(buildPageElement).not.toHaveBeenCalled();
+    expect(renderHttpAccessFallbackPage).toHaveBeenCalledWith(
+      404,
+      { matchedParams: { slug: "hello" } },
+      null,
+    );
+  });
+
   it("does not bypass cached production HTML for arbitrary draft cookie values", async () => {
     vi.stubEnv("__VINEXT_DRAFT_SECRET", "draft-secret");
     const isrGet = vi.fn(async () =>