Add logout flow and header sign-out button

app/api/logout/route.ts

@@ -0,0 +1,16 @@
+import { NextResponse } from "next/server";
+import { cookieName } from "@/lib/auth";
+
+export async function POST() {
+  const res = NextResponse.json({ ok: true });
+  res.cookies.set(cookieName, "", {
+    httpOnly: true,
+    sameSite: "lax",
+    secure: process.env.NODE_ENV === "production",
+    maxAge: 0,
+    expires: new Date(0),
+    path: "/"
+  });
+
+  return res;
+}

app/layout.tsx

@@ -3,6 +3,7 @@ import type { Metadata } from "next";
 import Link from "next/link";
 import { ReactNode } from "react";
 import { cookies } from "next/headers";
+import { LogoutButton } from "@/components/LogoutButton";
 import { cookieName, verifySession } from "@/lib/auth";
 
 export const metadata: Metadata = {
@@ -44,9 +45,12 @@ export default async function RootLayout({ children }: { children: ReactNode })
               </nav>
 
               {session ? (
-                <span className="rounded-full bg-slate-100 px-3 py-1 text-xs font-medium text-slate-700">
+                <div className="flex items-center gap-2">
-                  {userName}
+                  <span className="rounded-full bg-slate-100 px-3 py-1 text-xs font-medium text-slate-700">
-                </span>
+                    {userName}
+                  </span>
+                  <LogoutButton />
+                </div>
               ) : (
                 <div className="flex items-center gap-2">
                   <Link

components/LogoutButton.tsx

@@ -0,0 +1,44 @@
+"use client";
+
+import { useRouter } from "next/navigation";
+import { useState } from "react";
+
+const LOGOUT_FAILED_TEXT = "\u9000\u51fa\u767b\u5f55\u5931\u8d25";
+const LOGGING_OUT_TEXT = "\u9000\u51fa\u4e2d...";
+const LOGOUT_TEXT = "\u9000\u51fa\u767b\u5f55";
+
+export function LogoutButton() {
+  const router = useRouter();
+  const [loading, setLoading] = useState(false);
+
+  async function handleLogout() {
+    if (loading) return;
+
+    setLoading(true);
+    try {
+      const res = await fetch("/api/logout", { method: "POST" });
+      const data = await res.json().catch(() => ({}));
+
+      if (!res.ok) {
+        alert(data.error || LOGOUT_FAILED_TEXT);
+        return;
+      }
+
+      router.replace("/");
+      router.refresh();
+    } finally {
+      setLoading(false);
+    }
+  }
+
+  return (
+    <button
+      type="button"
+      onClick={handleLogout}
+      disabled={loading}
+      className="rounded-full bg-red-50 px-3 py-1 text-xs font-medium text-red-600 ring-1 ring-red-100 hover:bg-red-100 disabled:cursor-not-allowed disabled:opacity-60"
+    >
+      {loading ? LOGGING_OUT_TEXT : LOGOUT_TEXT}
+    </button>
+  );
+}