diff --git a/Cargo.lock b/Cargo.lock
index d423c35..8f8495d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1968,7 +1968,7 @@ dependencies = [
 
 [[package]]
 name = "secrets-mcp"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "anyhow",
  "askama",
diff --git a/crates/secrets-mcp/Cargo.toml b/crates/secrets-mcp/Cargo.toml
index 8b0e268..33c44da 100644
--- a/crates/secrets-mcp/Cargo.toml
+++ b/crates/secrets-mcp/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "secrets-mcp"
-version = "0.2.1"
+version = "0.2.2"
 edition.workspace = true
 
 [[bin]]
diff --git a/crates/secrets-mcp/src/web.rs b/crates/secrets-mcp/src/web.rs
index 44b36d8..be2f451 100644
--- a/crates/secrets-mcp/src/web.rs
+++ b/crates/secrets-mcp/src/web.rs
@@ -39,6 +39,15 @@ const SESSION_LOGIN_PROVIDER: &str = "login_provider";
 #[template(path = "login.html")]
 struct LoginTemplate {
     has_google: bool,
+    base_url: String,
+    version: &'static str,
+}
+
+#[derive(Template)]
+#[template(path = "home.html")]
+struct HomeTemplate {
+    is_logged_in: bool,
+    base_url: String,
     version: &'static str,
 }
 
@@ -134,7 +143,8 @@ pub fn web_router() -> Router<AppState> {
             "/.well-known/oauth-protected-resource",
             get(oauth_protected_resource_metadata),
         )
-        .route("/", get(login_page))
+        .route("/", get(home_page))
+        .route("/login", get(login_page))
         .route("/auth/google", get(auth_google))
         .route("/auth/google/callback", get(auth_google_callback))
         .route("/auth/logout", post(auth_logout))
@@ -188,6 +198,21 @@ async fn favicon_svg() -> Response {
         .expect("favicon response")
 }
 
+// ── Home page (public) ───────────────────────────────────────────────────────
+
+async fn home_page(
+    State(state): State<AppState>,
+    session: Session,
+) -> Result<Response, StatusCode> {
+    let is_logged_in = current_user_id(&session).await.is_some();
+    let tmpl = HomeTemplate {
+        is_logged_in,
+        base_url: state.base_url.clone(),
+        version: env!("CARGO_PKG_VERSION"),
+    };
+    render_template(tmpl)
+}
+
 // ── Login page ────────────────────────────────────────────────────────────────
 
 async fn login_page(
@@ -200,6 +225,7 @@ async fn login_page(
 
     let tmpl = LoginTemplate {
         has_google: state.google_config.is_some(),
+        base_url: state.base_url.clone(),
         version: env!("CARGO_PKG_VERSION"),
     };
     render_template(tmpl)
@@ -282,16 +308,16 @@ where
 {
     if let Some(err) = params.error {
         tracing::warn!(provider, error = %err, "OAuth error");
-        return Ok(Redirect::to("/?error=oauth_error").into_response());
+        return Ok(Redirect::to("/login?error=oauth_error").into_response());
     }
 
     let Some(code) = params.code else {
         tracing::warn!(provider, "OAuth callback missing code");
-        return Ok(Redirect::to("/?error=oauth_missing_code").into_response());
+        return Ok(Redirect::to("/login?error=oauth_missing_code").into_response());
     };
     let Some(returned_state) = params.state.as_deref() else {
         tracing::warn!(provider, "OAuth callback missing state");
-        return Ok(Redirect::to("/?error=oauth_missing_state").into_response());
+        return Ok(Redirect::to("/login?error=oauth_missing_state").into_response());
     };
 
     let expected_state: Option<String> = session.get(SESSION_OAUTH_STATE).await.map_err(|e| {
@@ -304,7 +330,7 @@ where
             expected_present = expected_state.is_some(),
             "OAuth state mismatch (empty session often means SameSite=Strict or server restart)"
         );
-        return Ok(Redirect::to("/?error=oauth_state").into_response());
+        return Ok(Redirect::to("/login?error=oauth_state").into_response());
     }
     if let Err(e) = session.remove::<String>(SESSION_OAUTH_STATE).await {
         tracing::warn!(provider, error = %e, "failed to remove oauth_state from session");
@@ -430,7 +456,7 @@ async fn dashboard(
     session: Session,
 ) -> Result<Response, StatusCode> {
     let Some(user_id) = current_user_id(&session).await else {
-        return Ok(Redirect::to("/").into_response());
+        return Ok(Redirect::to("/login").into_response());
     };
 
     let user = match get_user_by_id(&state.pool, user_id).await.map_err(|e| {
@@ -438,7 +464,7 @@ async fn dashboard(
         StatusCode::INTERNAL_SERVER_ERROR
     })? {
         Some(u) => u,
-        None => return Ok(Redirect::to("/").into_response()),
+        None => return Ok(Redirect::to("/login").into_response()),
     };
 
     let tmpl = DashboardTemplate {
@@ -457,7 +483,7 @@ async fn audit_page(
     session: Session,
 ) -> Result<Response, StatusCode> {
     let Some(user_id) = current_user_id(&session).await else {
-        return Ok(Redirect::to("/").into_response());
+        return Ok(Redirect::to("/login").into_response());
     };
 
     let user = match get_user_by_id(&state.pool, user_id).await.map_err(|e| {
@@ -465,7 +491,7 @@ async fn audit_page(
         StatusCode::INTERNAL_SERVER_ERROR
     })? {
         Some(u) => u,
-        None => return Ok(Redirect::to("/").into_response()),
+        None => return Ok(Redirect::to("/login").into_response()),
     };
 
     let rows = list_for_user(&state.pool, user_id, 100)
diff --git a/crates/secrets-mcp/static/llms.txt b/crates/secrets-mcp/static/llms.txt
index e8fa819..e7672e3 100644
--- a/crates/secrets-mcp/static/llms.txt
+++ b/crates/secrets-mcp/static/llms.txt
@@ -2,10 +2,15 @@
 
 > 给 AI 与自动化工具的简要说明。本站是 **secrets-mcp**：Streamable HTTP **MCP**（Model Context Protocol）与 **Web 控制台** 的组合，用于在多租户场景下存储条目元数据与加密后的秘密字段；持久化在 PostgreSQL。用户通过 OAuth（如已配置）登录 Web；MCP 调用使用 API Key 与加密相关请求头。
 
+## 公开页面
+
+- **`/`**：公开首页，说明安全架构（客户端密钥派生、密文存储、多租户与审计等），无需登录。
+
 ## 不应抓取或索引的内容
 
 - **`/mcp`**：MCP 流式 HTTP 端点（JSON-RPC 等），**不是** HTML 文档，也不适合作为公开知识库来源。
 - **`/api/*`**：会话或 API Key 相关的 HTTP API。
+- **`/login`**：登录入口页（`noindex` / robots 通常 disallow）。
 - **`/dashboard`、`/audit`、`/auth/*`、`/account/*`**：需浏览器会话，属于用户私有界面与 OAuth 流程。
 
 ## 给 AI 助手的实用提示
@@ -16,7 +21,7 @@
 
 ## 延伸阅读
 
-- 开源仓库中的 `README.md`、`AGENTS.md`（若可访问）包含环境变量、表结构与运维约定。
+- 源码仓库：<https://gitea.refining.dev/refining/secrets>（`README.md`、`AGENTS.md` 含环境变量、表结构与运维约定）。
 
 ## 关于本文件
 
diff --git a/crates/secrets-mcp/static/robots.txt b/crates/secrets-mcp/static/robots.txt
index 51bcb18..4109430 100644
--- a/crates/secrets-mcp/static/robots.txt
+++ b/crates/secrets-mcp/static/robots.txt
@@ -8,8 +8,11 @@ Disallow: /api/
 Disallow: /dashboard
 Disallow: /audit
 Disallow: /auth/
+Disallow: /login
 Disallow: /account/
 
+# 首页 `/` 为公开安全说明页，允许抓取。
+
 # 面向 AI / LLM 的机器可读站点说明（Markdown）：/llms.txt
 # Human & AI-readable site summary: /llms.txt (also /ai.txt)
 
@@ -24,4 +27,5 @@ Disallow: /api/
 Disallow: /dashboard
 Disallow: /audit
 Disallow: /auth/
+Disallow: /login
 Disallow: /account/
diff --git a/crates/secrets-mcp/templates/home.html b/crates/secrets-mcp/templates/home.html
new file mode 100644
index 0000000..a5d34ee
--- /dev/null
+++ b/crates/secrets-mcp/templates/home.html
@@ -0,0 +1,269 @@
+<!DOCTYPE html>
+<html lang="zh-CN">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <meta name="description" content="Secrets MCP：基于 Model Context Protocol 的密钥与配置管理。密码短语在浏览器本地 PBKDF2 派生，密文 AES-GCM 存储，完整审计与历史版本。">
+    <meta name="keywords" content="secrets management,MCP,Model Context Protocol,end-to-end encryption,AES-GCM,PBKDF2,API key,密钥管理">
+    <meta name="robots" content="index, follow">
+    <link rel="canonical" href="{{ base_url }}/">
+    <link rel="icon" href="/favicon.svg?v={{ version }}" type="image/svg+xml">
+    <title>Secrets MCP — 端到端加密的密钥管理</title>
+    <meta property="og:type" content="website">
+    <meta property="og:url" content="{{ base_url }}/">
+    <meta property="og:title" content="Secrets MCP — 端到端加密的密钥管理">
+    <meta property="og:description" content="密码短语客户端派生，密文存储；MCP API 与 Web 控制台，多租户与审计。">
+    <meta name="twitter:card" content="summary">
+    <meta name="twitter:title" content="Secrets MCP — 端到端加密的密钥管理">
+    <meta name="twitter:description" content="密码短语客户端派生，密文存储；MCP API 与 Web 控制台，多租户与审计。">
+    <style>
+        *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
+        @import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@500;600&family=Inter:wght@400;500;600&display=swap');
+        :root {
+            --bg: #0d1117;
+            --surface: #161b22;
+            --surface2: #21262d;
+            --border: #30363d;
+            --text: #e6edf3;
+            --text-muted: #8b949e;
+            --accent: #58a6ff;
+            --accent-hover: #79b8ff;
+        }
+        html, body { height: 100%; overflow: hidden; }
+        @supports (height: 100dvh) {
+            html, body { height: 100dvh; }
+        }
+        body {
+            background: var(--bg);
+            color: var(--text);
+            font-family: 'Inter', sans-serif;
+            display: flex;
+            flex-direction: column;
+        }
+        .nav {
+            flex-shrink: 0;
+            display: flex;
+            align-items: center;
+            justify-content: space-between;
+            padding: 14px 24px;
+            border-bottom: 1px solid var(--border);
+            background: var(--surface);
+        }
+        .brand {
+            font-family: 'JetBrains Mono', monospace;
+            font-size: 15px;
+            font-weight: 600;
+            color: var(--text);
+            text-decoration: none;
+        }
+        .brand span { color: var(--accent); }
+        .nav-right { display: flex; align-items: center; gap: 14px; }
+        .lang-bar { display: flex; gap: 2px; background: rgba(255,255,255,0.04); border-radius: 6px; padding: 2px; }
+        .lang-btn {
+            padding: 4px 10px; border: none; background: none; color: var(--text-muted);
+            font-size: 12px; cursor: pointer; border-radius: 4px;
+        }
+        .lang-btn.active { background: var(--border); color: var(--text); }
+        .cta {
+            display: inline-flex; align-items: center; justify-content: center;
+            padding: 8px 18px; border-radius: 8px; font-size: 13px; font-weight: 600;
+            text-decoration: none; border: 1px solid var(--accent);
+            background: rgba(88, 166, 255, 0.12); color: var(--accent);
+            transition: background 0.15s, color 0.15s;
+        }
+        .cta:hover { background: var(--accent); color: var(--bg); }
+        .main {
+            flex: 1;
+            min-height: 0;
+            display: flex;
+            flex-direction: column;
+            align-items: center;
+            justify-content: center;
+            padding: 16px 24px 12px;
+            gap: 20px;
+        }
+        .hero { text-align: center; max-width: 720px; }
+        .hero h1 { font-size: clamp(20px, 4vw, 28px); font-weight: 600; margin-bottom: 8px; line-height: 1.25; }
+        .hero .tagline { color: var(--text-muted); font-size: clamp(13px, 2vw, 15px); line-height: 1.5; }
+        .grid {
+            display: grid;
+            grid-template-columns: repeat(3, 1fr);
+            gap: 12px;
+            width: 100%;
+            max-width: 900px;
+        }
+        @media (max-width: 900px) {
+            .grid { grid-template-columns: repeat(2, 1fr); }
+        }
+        @media (max-width: 480px) {
+            .grid { grid-template-columns: 1fr; gap: 8px; }
+            .main { justify-content: flex-start; padding-top: 12px; }
+        }
+        .card {
+            background: var(--surface);
+            border: 1px solid var(--border);
+            border-radius: 10px;
+            padding: 14px 14px 12px;
+            min-height: 0;
+        }
+        .card-icon {
+            width: 32px; height: 32px; border-radius: 8px;
+            background: var(--surface2);
+            display: flex; align-items: center; justify-content: center;
+            margin-bottom: 10px; color: var(--accent);
+        }
+        .card-icon svg { width: 18px; height: 18px; }
+        .card h2 { font-size: 13px; font-weight: 600; margin-bottom: 6px; line-height: 1.3; }
+        .card p { font-size: 12px; color: var(--text-muted); line-height: 1.45; }
+        .foot {
+            flex-shrink: 0;
+            text-align: center;
+            padding: 8px 16px 12px;
+            font-size: 11px;
+            color: var(--text-muted);
+            border-top: 1px solid var(--border);
+            background: var(--surface);
+        }
+        .foot a { color: var(--accent); text-decoration: none; }
+        .foot a:hover { text-decoration: underline; }
+    </style>
+</head>
+<body>
+    <header class="nav">
+        <a class="brand" href="/">secrets<span>-mcp</span></a>
+        <div class="nav-right">
+            <div class="lang-bar">
+                <button type="button" class="lang-btn" onclick="setLang('zh-CN')">简</button>
+                <button type="button" class="lang-btn" onclick="setLang('zh-TW')">繁</button>
+                <button type="button" class="lang-btn" onclick="setLang('en')">EN</button>
+            </div>
+            {% if is_logged_in %}
+            <a class="cta" href="/dashboard" data-i18n="ctaDashboard">进入控制台</a>
+            {% else %}
+            <a class="cta" href="/login" data-i18n="ctaLogin">登录</a>
+            {% endif %}
+        </div>
+    </header>
+    <main class="main">
+        <div class="hero">
+            <h1 data-i18n="heroTitle">端到端加密的密钥与配置管理</h1>
+            <p class="tagline" data-i18n="heroTagline">Streamable HTTP MCP 与 Web 控制台：元数据与密文分库存储，密钥永不离开你的客户端逻辑。</p>
+        </div>
+        <div class="grid">
+            <article class="card">
+                <div class="card-icon" aria-hidden="true">
+                    <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M12 11c1.66 0 3-1.34 3-3V5c0-1.66-1.34-3-3-3S9 3.34 9 5v3c0 1.66 1.34 3 3 3z"/><path d="M19 10v1a7 7 0 01-14 0v-1"/><path d="M12 14v7M9 18h6"/></svg>
+                </div>
+                <h2 data-i18n="c1t">客户端密钥派生</h2>
+                <p data-i18n="c1d">PBKDF2-SHA256（约 60 万次）在浏览器本地从密码短语派生密钥；服务端仅保存盐与校验值，不持有密码或明文主密钥。</p>
+            </article>
+            <article class="card">
+                <div class="card-icon" aria-hidden="true">
+                    <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><rect x="3" y="11" width="18" height="11" rx="2"/><path d="M7 11V7a5 5 0 0110 0v4"/></svg>
+                </div>
+                <h2 data-i18n="c2t">AES-256-GCM 加密</h2>
+                <p data-i18n="c2d">敏感字段以 AES-GCM 密文落库；Web 端在本地加解密，明文默认不经过服务端持久化。</p>
+            </article>
+            <article class="card">
+                <div class="card-icon" aria-hidden="true">
+                    <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M14 2H6a2 2 0 00-2 2v16a2 2 0 002 2h12a2 2 0 002-2V8z"/><path d="M14 2v6h6M16 13H8M16 17H8M10 9H8"/></svg>
+                </div>
+                <h2 data-i18n="c3t">审计与历史</h2>
+                <p data-i18n="c3d">操作写入审计日志；条目与密文保留历史版本，支持按版本查看与恢复。</p>
+            </article>
+        </div>
+    </main>
+    <footer class="foot">
+        <span data-i18n="versionLabel">版本</span> {{ version }} ·
+        <a href="/llms.txt">llms.txt</a>
+        <span data-i18n="sep"> · </span>
+        <a href="https://gitea.refining.dev/refining/secrets" target="_blank" rel="noopener noreferrer" data-i18n="footRepo">源码仓库</a>
+        {% if !is_logged_in %}
+        <span data-i18n="sep"> · </span>
+        <a href="/login" data-i18n="footLogin">登录</a>
+        {% endif %}
+    </footer>
+    <script>
+    const T = {
+        'zh-CN': {
+            docTitle: 'Secrets MCP — 端到端加密的密钥管理',
+            ctaDashboard: '进入控制台',
+            ctaLogin: '登录',
+            heroTitle: '端到端加密的密钥与配置管理',
+            heroTagline: 'Streamable HTTP MCP 与 Web 控制台：元数据与密文分库存储，密钥永不离开你的客户端逻辑。',
+            c1t: '客户端密钥派生',
+            c1d: 'PBKDF2-SHA256（约 60 万次）在浏览器本地从密码短语派生密钥；服务端仅保存盐与校验值，不持有密码或明文主密钥。',
+            c2t: 'AES-256-GCM 加密',
+            c2d: '敏感字段以 AES-GCM 密文落库；Web 端在本地加解密，明文默认不经过服务端持久化。',
+            c3t: '审计与历史',
+            c3d: '操作写入审计日志；条目与密文保留历史版本，支持按版本查看与恢复。',
+            versionLabel: '版本',
+            sep: ' · ',
+            footRepo: '源码仓库',
+            footLogin: '登录',
+        },
+        'zh-TW': {
+            docTitle: 'Secrets MCP — 端到端加密的金鑰管理',
+            ctaDashboard: '進入控制台',
+            ctaLogin: '登入',
+            heroTitle: '端到端加密的金鑰與設定管理',
+            heroTagline: 'Streamable HTTP MCP 與 Web 控制台：中繼資料與密文分庫儲存，金鑰不離開你的用戶端邏輯。',
+            c1t: '用戶端金鑰派生',
+            c1d: 'PBKDF2-SHA256（約 60 萬次）在瀏覽器本地從密碼片語派生金鑰；伺服端僅保存鹽與校驗值，不持有密碼或明文主金鑰。',
+            c2t: 'AES-256-GCM 加密',
+            c2d: '敏感欄位以 AES-GCM 密文落庫；Web 端在本地加解密，明文預設不經伺服端持久化。',
+            c3t: '稽核與歷史',
+            c3d: '操作寫入稽核日誌；條目與密文保留歷史版本，支援依版本檢視與還原。',
+            versionLabel: '版本',
+            sep: ' · ',
+            footRepo: '原始碼倉庫',
+            footLogin: '登入',
+        },
+        'en': {
+            docTitle: 'Secrets MCP — End-to-end encrypted secrets',
+            ctaDashboard: 'Open dashboard',
+            ctaLogin: 'Sign in',
+            heroTitle: 'End-to-end encrypted secrets and configuration',
+            heroTagline: 'Streamable HTTP MCP plus web console: metadata and ciphertext stored separately; keys stay on your client.',
+            c1t: 'Client-side key derivation',
+            c1d: 'PBKDF2-SHA256 (~600k iterations) derives keys from your passphrase in the browser; the server stores only salt and a verification blob, never your password or raw master key.',
+            c2t: 'AES-256-GCM',
+            c2d: 'Secret fields are stored as AES-GCM ciphertext; the web UI encrypts and decrypts locally so plaintext is not persisted server-side by default.',
+            c3t: 'Audit and history',
+            c3d: 'Operations are audited; entries and secrets keep version history for review and rollback.',
+            versionLabel: 'Version',
+            sep: ' · ',
+            footRepo: 'Source repository',
+            footLogin: 'Sign in',
+        }
+    };
+
+    let currentLang = localStorage.getItem('lang') || 'zh-CN';
+
+    function t(key) {
+        return (T[currentLang] && T[currentLang][key]) || T['en'][key] || key;
+    }
+
+    function applyLang() {
+        document.documentElement.lang = currentLang;
+        document.title = t('docTitle');
+        document.querySelectorAll('[data-i18n]').forEach(el => {
+            const key = el.getAttribute('data-i18n');
+            el.textContent = t(key);
+        });
+        document.querySelectorAll('.lang-btn').forEach(btn => {
+            const map = { 'zh-CN': '简', 'zh-TW': '繁', 'en': 'EN' };
+            btn.classList.toggle('active', btn.textContent === map[currentLang]);
+        });
+    }
+
+    function setLang(lang) {
+        currentLang = lang;
+        localStorage.setItem('lang', lang);
+        applyLang();
+    }
+
+    applyLang();
+    </script>
+</body>
+</html>
diff --git a/crates/secrets-mcp/templates/login.html b/crates/secrets-mcp/templates/login.html
index 835e507..a7cedee 100644
--- a/crates/secrets-mcp/templates/login.html
+++ b/crates/secrets-mcp/templates/login.html
@@ -3,8 +3,19 @@
 <head>
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <meta name="robots" content="noindex, follow">
+    <meta name="description" content="登录 Secrets MCP Web 控制台，安全管理跨设备加密 secrets。">
+    <meta name="keywords" content="Secrets MCP,登录,OAuth,密钥管理">
+    <link rel="canonical" href="{{ base_url }}/login">
     <link rel="icon" href="/favicon.svg?v={{ version }}" type="image/svg+xml">
-    <title>Secrets — Sign In</title>
+    <title>登录 — Secrets MCP</title>
+    <meta property="og:type" content="website">
+    <meta property="og:url" content="{{ base_url }}/login">
+    <meta property="og:title" content="登录 — Secrets MCP">
+    <meta property="og:description" content="登录 Web 控制台，管理加密存储的密钥与配置。">
+    <meta name="twitter:card" content="summary">
+    <meta name="twitter:title" content="登录 — Secrets MCP">
+    <meta name="twitter:description" content="登录 Web 控制台，管理加密存储的密钥与配置。">
     <style>
         *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
         @import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&display=swap');
@@ -17,6 +28,7 @@
             --accent: #58a6ff;
             --accent-hover: #79b8ff;
             --google: #4285f4;
+            --danger: #f85149;
         }
         body { background: var(--bg); color: var(--text); font-family: 'Inter', sans-serif;
                min-height: 100vh; display: flex; align-items: center; justify-content: center; }
@@ -25,11 +37,24 @@
             padding: 48px 40px; width: 100%; max-width: 400px;
             box-shadow: 0 8px 32px rgba(0,0,0,0.4);
         }
-        .topbar { display: flex; justify-content: flex-end; margin-bottom: 20px; }
-        .lang-bar { display: flex; gap: 2px; background: rgba(255,255,255,0.04); border-radius: 6px; padding: 2px; }
+        .topbar { display: flex; justify-content: space-between; align-items: flex-start; margin-bottom: 20px; gap: 12px; }
+        .back-home {
+            font-size: 13px; color: var(--accent); text-decoration: none; white-space: nowrap;
+        }
+        .back-home:hover { text-decoration: underline; }
+        .lang-bar { display: flex; gap: 2px; background: rgba(255,255,255,0.04); border-radius: 6px; padding: 2px; flex-shrink: 0; }
         .lang-btn { padding: 3px 9px; border: none; background: none; color: var(--text-muted);
                     font-size: 12px; cursor: pointer; border-radius: 4px; }
         .lang-btn.active { background: var(--border); color: var(--text); }
+        .oauth-alert {
+            display: none;
+            margin-bottom: 16px; padding: 10px 12px; border-radius: 8px;
+            font-size: 13px; line-height: 1.4;
+            background: rgba(248, 81, 73, 0.12);
+            border: 1px solid rgba(248, 81, 73, 0.35);
+            color: #ffa198;
+        }
+        .oauth-alert.visible { display: block; }
         h1 { font-size: 22px; font-weight: 600; margin-bottom: 8px; }
         .subtitle { color: var(--text-muted); font-size: 14px; margin-bottom: 32px; }
         .btn {
@@ -48,12 +73,14 @@
 <body>
     <div class="card">
         <div class="topbar">
+            <a class="back-home" href="/" data-i18n="backHome">返回首页</a>
             <div class="lang-bar">
-                <button class="lang-btn" onclick="setLang('zh-CN')">简</button>
-                <button class="lang-btn" onclick="setLang('zh-TW')">繁</button>
-                <button class="lang-btn" onclick="setLang('en')">EN</button>
+                <button type="button" class="lang-btn" onclick="setLang('zh-CN')">简</button>
+                <button type="button" class="lang-btn" onclick="setLang('zh-TW')">繁</button>
+                <button type="button" class="lang-btn" onclick="setLang('en')">EN</button>
             </div>
         </div>
+        <div id="oauth-alert" class="oauth-alert" role="alert"></div>
         <h1 data-i18n="title">登录</h1>
         <p class="subtitle" data-i18n="subtitle">安全管理你的跨设备 secrets。</p>
 
@@ -78,22 +105,40 @@
     <script>
     const T = {
         'zh-CN': {
+            docTitle: '登录 — Secrets MCP',
+            backHome: '返回首页',
             title: '登录',
             subtitle: '安全管理你的跨设备 secrets。',
             google: '使用 Google 登录',
             noProviders: '未配置登录方式，请联系管理员。',
+            err_oauth_error: '登录失败：授权提供方返回错误，请重试。',
+            err_oauth_missing_code: '登录失败：未收到授权码，请重试。',
+            err_oauth_missing_state: '登录失败：缺少安全校验参数，请重试。',
+            err_oauth_state: '登录失败：会话校验不匹配（可能因 Cookie 策略或服务器重启）。请返回首页再试。',
         },
         'zh-TW': {
+            docTitle: '登入 — Secrets MCP',
+            backHome: '返回首頁',
             title: '登入',
             subtitle: '安全管理你的跨裝置 secrets。',
             google: '使用 Google 登入',
             noProviders: '尚未設定登入方式，請聯絡管理員。',
+            err_oauth_error: '登入失敗：授權方回傳錯誤，請再試一次。',
+            err_oauth_missing_code: '登入失敗：未取得授權碼，請再試一次。',
+            err_oauth_missing_state: '登入失敗：缺少安全校驗參數，請再試一次。',
+            err_oauth_state: '登入失敗：工作階段校驗不符（可能與 Cookie 政策或伺服器重啟有關）。請回到首頁再試。',
         },
         'en': {
+            docTitle: 'Sign in — Secrets MCP',
+            backHome: 'Back to home',
             title: 'Sign in',
             subtitle: 'Manage your cross-device secrets securely.',
             google: 'Continue with Google',
             noProviders: 'No login providers configured. Please contact your administrator.',
+            err_oauth_error: 'Sign-in failed: the identity provider returned an error. Please try again.',
+            err_oauth_missing_code: 'Sign-in failed: no authorization code was returned. Please try again.',
+            err_oauth_missing_state: 'Sign-in failed: missing security state. Please try again.',
+            err_oauth_state: 'Sign-in failed: session state mismatch (often cookies or server restart). Open the home page and try again.',
         }
     };
 
@@ -101,8 +146,23 @@
 
     function t(key) { return T[currentLang][key] || T['en'][key] || key; }
 
+    function showOAuthError() {
+        const params = new URLSearchParams(window.location.search);
+        const code = params.get('error');
+        const el = document.getElementById('oauth-alert');
+        if (!code || !code.startsWith('oauth_')) {
+            el.classList.remove('visible');
+            el.textContent = '';
+            return;
+        }
+        const key = 'err_' + code;
+        el.textContent = t(key) || t('err_oauth_error');
+        el.classList.add('visible');
+    }
+
     function applyLang() {
         document.documentElement.lang = currentLang;
+        document.title = t('docTitle');
         document.querySelectorAll('[data-i18n]').forEach(el => {
             const key = el.getAttribute('data-i18n');
             el.textContent = t(key);
@@ -111,6 +171,7 @@
             const map = { 'zh-CN': '简', 'zh-TW': '繁', 'en': 'EN' };
             btn.classList.toggle('active', btn.textContent === map[currentLang]);
         });
+        showOAuthError();
     }
 
     function setLang(lang) {