diff --git a/app/api/auth/logout/route.ts b/app/api/auth/logout/route.ts
index 12fd2af..938680d 100644
--- a/app/api/auth/logout/route.ts
+++ b/app/api/auth/logout/route.ts
@@ -1,10 +1,15 @@
-import { NextResponse } from "next/server";
+import { NextRequest, NextResponse } from "next/server";
+import { getAuthCookieDomain } from "@/app/lib/auth-cookie-domain";
 
 const COOKIE_NAME = "pb_session";
-const COOKIE_DOMAIN = process.env.AUTH_COOKIE_DOMAIN || ".hackrobot.cn";
 
-export async function POST() {
+export async function POST(request: NextRequest) {
+  const domain = getAuthCookieDomain(request);
   const res = NextResponse.json({ ok: true });
-  res.cookies.set(COOKIE_NAME, "", { domain: COOKIE_DOMAIN, path: "/", maxAge: 0 });
+  res.cookies.set(COOKIE_NAME, "", {
+    ...(domain && { domain }),
+    path: "/",
+    maxAge: 0,
+  });
   return res;
 }
diff --git a/app/api/auth/me/route.ts b/app/api/auth/me/route.ts
index 89569eb..22e3efe 100644
--- a/app/api/auth/me/route.ts
+++ b/app/api/auth/me/route.ts
@@ -1,12 +1,13 @@
 import { NextRequest, NextResponse } from "next/server";
 import { getPocketBaseConfig } from "@/config/services.config";
+import { getAuthCookieDomain } from "@/app/lib/auth-cookie-domain";
 
 const COOKIE_NAME = "pb_session";
-const COOKIE_DOMAIN = process.env.AUTH_COOKIE_DOMAIN || ".hackrobot.cn";
 const COOKIE_MAX_AGE = 60 * 60 * 24 * 365;
 
 export async function GET(request: NextRequest) {
   const cookie = request.cookies.get(COOKIE_NAME)?.value;
+  const domain = getAuthCookieDomain(request);
   if (!cookie) {
     return NextResponse.json({ ok: true, user: null });
   }
@@ -21,7 +22,7 @@ export async function GET(request: NextRequest) {
     });
     if (!res.ok) {
       const r = NextResponse.json({ ok: true, user: null });
-      r.cookies.set(COOKIE_NAME, "", { domain: COOKIE_DOMAIN, path: "/", maxAge: 0 });
+      r.cookies.set(COOKIE_NAME, "", { ...(domain && { domain }), path: "/", maxAge: 0 });
       return r;
     }
     const data = await res.json();
@@ -40,7 +41,7 @@ export async function GET(request: NextRequest) {
         token: newToken,
       });
       r.cookies.set(COOKIE_NAME, encoded, {
-        domain: COOKIE_DOMAIN,
+        ...(domain && { domain }),
         path: "/",
         maxAge: COOKIE_MAX_AGE,
         secure: process.env.NODE_ENV === "production",
diff --git a/app/api/auth/sync-session/route.ts b/app/api/auth/sync-session/route.ts
index 0578d90..23018db 100644
--- a/app/api/auth/sync-session/route.ts
+++ b/app/api/auth/sync-session/route.ts
@@ -1,8 +1,8 @@
 import { NextRequest, NextResponse } from "next/server";
+import { getAuthCookieDomain } from "@/app/lib/auth-cookie-domain";
 
 const COOKIE_NAME = "pb_session";
 const COOKIE_MAX_AGE = 60 * 60 * 24 * 365; // 365 天，登录态持续有效直至用户主动退出
-const COOKIE_DOMAIN = process.env.AUTH_COOKIE_DOMAIN || ".hackrobot.cn";
 
 export async function POST(request: NextRequest) {
   const body = await request.json().catch(() => ({}));
@@ -19,9 +19,10 @@ export async function POST(request: NextRequest) {
   });
   const encoded = Buffer.from(payload, "utf-8").toString("base64url");
 
+  const domain = getAuthCookieDomain(request);
   const res = NextResponse.json({ ok: true });
   res.cookies.set(COOKIE_NAME, encoded, {
-    domain: COOKIE_DOMAIN,
+    ...(domain && { domain }),
     path: "/",
     maxAge: COOKIE_MAX_AGE,
     secure: process.env.NODE_ENV === "production",
diff --git a/app/lib/auth-cookie-domain.ts b/app/lib/auth-cookie-domain.ts
new file mode 100644
index 0000000..555d48a
--- /dev/null
+++ b/app/lib/auth-cookie-domain.ts
@@ -0,0 +1,11 @@
+/**
+ * 根据请求 host 返回 Cookie domain。
+ * localhost 时不设 domain，生产环境用根域实现跨站 SSO。
+ */
+export function getAuthCookieDomain(request: { headers: { get: (name: string) => string | null } }): string | undefined {
+  const envDomain = process.env.AUTH_COOKIE_DOMAIN;
+  if (envDomain) return envDomain;
+  const host = request.headers.get("host") ?? "";
+  if (host.includes("localhost") || host.startsWith("127.0.0.1")) return undefined;
+  return process.env.AUTH_COOKIE_DOMAIN || ".hackrobot.cn";
+}
diff --git a/app/vip/components/VipHeader.tsx b/app/vip/components/VipHeader.tsx
index fc866ab..7a47a71 100644
--- a/app/vip/components/VipHeader.tsx
+++ b/app/vip/components/VipHeader.tsx
@@ -37,11 +37,7 @@ export function VipHeader({ isLoggedIn, userName, onLogout }: VipHeaderProps) {
               </button>
             )}
           </div>
-        ) : (
-          <Link href="/#login" className={styles.loginLink}>
-            登录
-          </Link>
-        )}
+        ) : null}
       </nav>
     </header>
   );