diff --git a/app/[locale]/join/page.tsx b/app/[locale]/join/page.tsx
index 6c57a3a..91b77b0 100644
--- a/app/[locale]/join/page.tsx
+++ b/app/[locale]/join/page.tsx
@@ -63,7 +63,7 @@ export default function JoinPage() {
   const checkAuth = useCallback(async () => {
     if (getStoredToken()) return true;
     try {
-      const res = await fetch("/api/auth/me");
+      const res = await fetch("/api/auth/me", { credentials: "include" });
       const data = await res.json();
       return !!(data?.user && data?.token);
     } catch {
diff --git a/app/components/AuthModal.tsx b/app/components/AuthModal.tsx
index 2d7540c..539c353 100644
--- a/app/components/AuthModal.tsx
+++ b/app/components/AuthModal.tsx
@@ -49,6 +49,7 @@ export default function AuthModal({ isOpen, onClose, onSuccess }: AuthModalProps
           method: "POST",
           headers: { "Content-Type": "application/json" },
           body: JSON.stringify({ token: result.token, record: result.record }),
+          credentials: "include",
         });
       } catch {
         /* ignore */
diff --git a/app/components/Header.tsx b/app/components/Header.tsx
index 53eb633..63e0c19 100644
--- a/app/components/Header.tsx
+++ b/app/components/Header.tsx
@@ -28,7 +28,7 @@ export default function Header() {
     let mounted = true;
     (async () => {
       try {
-        const res = await fetch("/api/auth/me");
+        const res = await fetch("/api/auth/me", { credentials: "include" });
         const data = await res.json();
         if (!mounted) return;
         if (data?.user && data?.token) {