Add login gate, calculation history, and AI markdown download.

Co-authored-by: Cursor <cursoragent@cursor.com>

components/header.tsx

@@ -1,27 +1,41 @@
 "use client";
+
 import Link from "next/link";
 import { usePathname } from "next/navigation";
+import { History, LogIn, LogOut } from "lucide-react";
 import { TaijiIcon } from "@/components/svg/taiji";
 import { ModeToggle } from "@/components/mode-toggle";
 import { SITE_WIDTH_INNER } from "@/components/layout/site-width";
+import { useAuth } from "@/components/auth/auth-provider";
+import { Button } from "@/components/ui/button";
 
 const NAV_ITEMS = [
-  { href: "/learn", label: "易经学习" },
-  { href: "/liuyao", label: "六爻算卦" },
-  { href: "/bazi", label: "生辰八字" },
-  { href: "/combined", label: "综合测算" },
-];
+  { href: "/learn", label: "易经学习", protected: false },
+  { href: "/liuyao", label: "六爻算卦", protected: true },
+  { href: "/bazi", label: "生辰八字", protected: true },
+  { href: "/combined", label: "综合测算", protected: true },
+] as const;
 
-function NavLink({ href, label }: { href: string; label: string }) {
+function NavLink({
+  href,
+  label,
+  needLogin,
+}: {
+  href: string;
+  label: string;
+  needLogin: boolean;
+}) {
   const pathname = usePathname();
   const active =
     href === "/"
       ? pathname === "/"
       : pathname === href || pathname.startsWith(`${href}/`);
 
+  const target = needLogin ? `/login?next=${encodeURIComponent(href)}` : href;
+
   return (
     <Link
-      href={href}
+      href={target}
       className={`whitespace-nowrap text-sm transition-colors ${
         active
           ? "font-medium text-foreground"
@@ -34,6 +48,8 @@ function NavLink({ href, label }: { href: string; label: string }) {
 }
 
 export default function Header() {
+  const { authEnabled, loggedIn, username, logout, loading } = useAuth();
+
   return (
     <header className="relative z-10 border-b border-border/40 bg-card/70 py-3 shadow-sm backdrop-blur-md">
       <div
@@ -43,13 +59,54 @@ export default function Header() {
           <TaijiIcon />
           <span className="font-medium tracking-wide">知命阁</span>
         </Link>
-        <div className="justify-self-end sm:order-last">
+        <div className="flex items-center justify-self-end gap-2 sm:order-last">
+          {!loading && authEnabled && loggedIn && (
+            <Link
+              href="/history"
+              className="hidden text-muted-foreground hover:text-foreground sm:inline-flex"
+              title="测算历史"
+            >
+              <History size={18} />
+            </Link>
+          )}
           <ModeToggle />
+          {!loading && authEnabled && (
+            loggedIn ? (
+              <Button
+                variant="ghost"
+                size="sm"
+                className="h-9 gap-1 px-2 text-xs"
+                onClick={() => logout()}
+              >
+                <LogOut size={16} />
+                <span className="hidden sm:inline">{username ?? "退出"}</span>
+              </Button>
+            ) : (
+              <Link href="/login">
+                <Button variant="ghost" size="sm" className="h-9 gap-1 px-2 text-xs">
+                  <LogIn size={16} />
+                  <span className="hidden sm:inline">登录</span>
+                </Button>
+              </Link>
+            )
+          )}
         </div>
         <nav className="col-span-2 flex flex-wrap items-center justify-center gap-x-4 gap-y-1 sm:order-none sm:col-span-1 sm:flex-1">
           {NAV_ITEMS.map((item) => (
-            <NavLink key={item.href} {...item} />
+            <NavLink
+              key={item.href}
+              {...item}
+              needLogin={item.protected && authEnabled && !loggedIn}
+            />
           ))}
+          {!loading && authEnabled && loggedIn && (
+            <Link
+              href="/history"
+              className="whitespace-nowrap text-sm text-muted-foreground hover:text-foreground sm:hidden"
+            >
+              测算历史
+            </Link>
+          )}
         </nav>
       </div>
     </header>