fix: prevent useActionState state becoming undefined when redirect() is called (#589)

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

@@ -2036,28 +2036,25 @@ async function _handleRequest(request, __reqCtx, _mwCtx) {
         setHeadersAccessPhase(previousHeadersPhase);
       }
 
-      // If the action called redirect(), signal the client to navigate.
-      // We can't use a real HTTP redirect (the fetch would follow it automatically
-      // and receive a page HTML instead of RSC stream). Instead, we return a 200
-      // with x-action-redirect header that the client entry detects and handles.
+      // If the action called redirect(), return a 303 redirect response.
+      // This matches Next.js behavior for server action redirects.
+      // The client will handle the redirect and navigate to the target URL.
       if (actionRedirect) {
         const actionPendingCookies = getAndClearPendingCookies();
         const actionDraftCookie = getDraftModeCookieHeader();
+
         setHeadersContext(null);
         setNavigationContext(null);
         const redirectHeaders = new Headers({
-          "Content-Type": "text/x-component; charset=utf-8",
-          "Vary": "RSC, Accept",
-          "x-action-redirect": actionRedirect.url,
-          "x-action-redirect-type": actionRedirect.type,
-          "x-action-redirect-status": String(actionRedirect.status),
+          Location: actionRedirect.url,
         });
         for (const cookie of actionPendingCookies) {
           redirectHeaders.append("Set-Cookie", cookie);
         }
         if (actionDraftCookie) redirectHeaders.append("Set-Cookie", actionDraftCookie);
-        // Send an empty RSC-like body (client will navigate instead of parsing)
-        return new Response("", { status: 200, headers: redirectHeaders });
+
+        // Return 303 See Other for server action redirects (Next.js behavior)
+        return new Response(null, { status: 303, headers: redirectHeaders });
       }
 
       // After the action, re-render the current page so the client

packages/vinext/src/server/app-browser-entry.ts

@@ -133,27 +133,25 @@ function registerServerActionCallback(): void {
 
     const actionRedirect = fetchResponse.headers.get("x-action-redirect");
     if (actionRedirect) {
+      // Check for external URLs that need a hard redirect.
       try {
         const redirectUrl = new URL(actionRedirect, window.location.origin);
         if (redirectUrl.origin !== window.location.origin) {
           window.location.href = actionRedirect;
           return undefined;
         }
       } catch {
-        // Fall through to client-side navigation if URL parsing fails.
+        // Fall through to hard redirect below if URL parsing fails.
       }
 
+      // For same-origin redirects, use hard redirect to ensure navigation completes.
+      // This matches Next.js behavior for server action redirects with useActionState.
       const redirectType = fetchResponse.headers.get("x-action-redirect-type") ?? "replace";
       if (redirectType === "push") {
-        window.history.pushState(null, "", actionRedirect);
+        window.location.assign(actionRedirect);
       } else {
-        window.history.replaceState(null, "", actionRedirect);
+        window.location.replace(actionRedirect);
       }
-
-      if (typeof window.__VINEXT_RSC_NAVIGATE__ === "function") {
-        await window.__VINEXT_RSC_NAVIGATE__(actionRedirect);
-      }
-
       return undefined;
     }