diff --git a/app/docs/[...slug]/page.tsx b/app/docs/[...slug]/page.tsx
index 3f251721..45dba950 100644
--- a/app/docs/[...slug]/page.tsx
+++ b/app/docs/[...slug]/page.tsx
@@ -93,8 +93,59 @@ export default async function DocPage({ params }: Param) {
     getDocContributorsByDocId(docIdFromPage);
   const Mdx = page.data.body;
 
+  // SEO 结构化数据
+  const siteUrl =
+    process.env.NEXT_PUBLIC_SITE_URL || "https://involutionhell.com";
+  const slugPath = (slug ?? []).join("/");
+  const docUrl = slugPath ? `${siteUrl}/docs/${slugPath}` : `${siteUrl}/docs`;
+
+  // TechArticle: 让 docs 在 Google 搜索结果上更可能展示为技术文章卡片
+  const articleJsonLd = {
+    "@context": "https://schema.org",
+    "@type": "TechArticle",
+    headline: page.data.title,
+    description: page.data.description,
+    url: docUrl,
+    inLanguage: locale === "en" ? "en-US" : "zh-CN",
+    publisher: {
+      "@type": "Organization",
+      name: "Involution Hell",
+      url: siteUrl,
+    },
+  };
+
+  // BreadcrumbList: 按 slug 层级生成面包屑（Google 搜索结果里的那种层级链接）
+  const breadcrumbItems = [
+    { name: "Involution Hell", url: siteUrl },
+    { name: "Docs", url: `${siteUrl}/docs` },
+    ...(slug ?? []).map((seg, idx) => ({
+      name: decodeURIComponent(seg),
+      url: `${siteUrl}/docs/${slug!.slice(0, idx + 1).join("/")}`,
+    })),
+  ];
+  const breadcrumbJsonLd = {
+    "@context": "https://schema.org",
+    "@type": "BreadcrumbList",
+    itemListElement: breadcrumbItems.map((item, idx) => ({
+      "@type": "ListItem",
+      position: idx + 1,
+      name: item.name,
+      item: item.url,
+    })),
+  };
+
   return (
     <>
+      <script
+        type="application/ld+json"
+        // eslint-disable-next-line react/no-danger
+        dangerouslySetInnerHTML={{ __html: JSON.stringify(articleJsonLd) }}
+      />
+      <script
+        type="application/ld+json"
+        // eslint-disable-next-line react/no-danger
+        dangerouslySetInnerHTML={{ __html: JSON.stringify(breadcrumbJsonLd) }}
+      />
       <DocsPage toc={page.data.toc}>
         <DocsBody>
           <div className="mb-6 flex flex-col gap-3 border-b border-border pb-6 md:mb-8 md:flex-row md:items-start md:justify-between">
@@ -144,8 +195,35 @@ export async function generateMetadata({ params }: Param): Promise<Metadata> {
     notFound();
   }
 
+  // 规范化 slug → canonical 路径。用户访问 /docs/ai/rl（原文）或 /docs/ai/rl.en（翻译版）
+  // 都统一指向原始 slug，避免两个 URL 竞争同一份内容的 PageRank。
+  const slugPath = (slug ?? []).join("/");
+  const canonical = slugPath ? `/docs/${slugPath}` : "/docs";
+
+  // hreflang：告诉搜索引擎该文档有哪些语言版本。
+  // 翻译版文件命名是 `<slug>.en.mdx` / `<slug>.zh.mdx`，URL 靠 cookie 切换，
+  // 两种语言走同一 canonical URL，因此 hreflang 都指向自己。
+  const languages: Record<string, string> = {
+    "zh-CN": canonical,
+    "en-US": canonical,
+    "x-default": canonical,
+  };
+
   return {
     title: page.data.title,
     description: page.data.description,
+    alternates: { canonical, languages },
+    openGraph: {
+      type: "article",
+      title: page.data.title,
+      description: page.data.description,
+      url: canonical,
+      locale: locale === "en" ? "en_US" : "zh_CN",
+    },
+    twitter: {
+      card: "summary_large_image",
+      title: page.data.title,
+      description: page.data.description,
+    },
   };
 }
diff --git a/app/layout.tsx b/app/layout.tsx
index 98786f21..203029d8 100644
--- a/app/layout.tsx
+++ b/app/layout.tsx
@@ -67,15 +67,16 @@ export const metadata: Metadata = {
     canonical: "/",
   },
   robots: {
+    // nocache 会抑制 rich snippet / cached page，对 SEO 反而不利；移除
     index: true,
     follow: true,
-    nocache: true,
     googleBot: {
       index: true,
       follow: true,
-      "max-image-preview": "standard",
-      "max-snippet": 160,
-      "max-video-preview": 0,
+      // 允许摘要长度，不要限制过短（160 char → -1 让 Google 自行判断）
+      "max-image-preview": "large",
+      "max-snippet": -1,
+      "max-video-preview": -1,
     },
   },
   formatDetection: {
@@ -187,6 +188,33 @@ export default async function RootLayout({
           type="image/png"
           fetchPriority="high"
         />
+        {/*
+          WebSite + SearchAction 结构化数据：Google 搜索结果下方可能直接显示站内搜索框
+          （Sitelinks Search Box）。target 指向我们的搜索页带 query 参数；
+          search-input 占位符必须叫 "search_term_string"（Google 硬约定）。
+        */}
+        <script
+          type="application/ld+json"
+          // eslint-disable-next-line react/no-danger
+          dangerouslySetInnerHTML={{
+            __html: JSON.stringify({
+              "@context": "https://schema.org",
+              "@type": "WebSite",
+              name: "Involution Hell",
+              alternateName: ["内卷地狱"],
+              url: SITE_URL,
+              inLanguage: ["zh-CN", "en-US"],
+              potentialAction: {
+                "@type": "SearchAction",
+                target: {
+                  "@type": "EntryPoint",
+                  urlTemplate: `${SITE_URL}/docs?q={search_term_string}`,
+                },
+                "query-input": "required name=search_term_string",
+              },
+            }),
+          }}
+        />
         {/* 结构化数据：英文主名 + 中文 alternateName */}
         <script
           type="application/ld+json"
diff --git a/app/login/page.tsx b/app/login/page.tsx
index bebeb2e6..69772bb0 100644
--- a/app/login/page.tsx
+++ b/app/login/page.tsx
@@ -1,6 +1,15 @@
+import type { Metadata } from "next";
 import { getTranslations } from "next-intl/server";
 import { SignInButton } from "@/app/components/SignInButton";
 
+// SEO: 登录页不参与 index（搜索引擎不需要收录登录入口）
+export const metadata: Metadata = {
+  title: "Sign In",
+  description: "Sign in to Involution Hell with GitHub.",
+  alternates: { canonical: "/login" },
+  robots: { index: false, follow: true },
+};
+
 export default async function LoginPage() {
   const t = await getTranslations("login");
   return (
diff --git a/app/rank/page.tsx b/app/rank/page.tsx
index 8b2a3c90..7b527c91 100644
--- a/app/rank/page.tsx
+++ b/app/rank/page.tsx
@@ -1,3 +1,4 @@
+import type { Metadata } from "next";
 import { Header } from "@/app/components/Header";
 import { Footer } from "@/app/components/Footer";
 import { ContributorRow } from "@/app/components/rank/ContributorRow";
@@ -6,6 +7,21 @@ import { Suspense } from "react";
 
 import leaderboardData from "@/generated/site-leaderboard.json";
 
+// SEO: rank 页用 canonical + 稳定 title/description，避免 tab/window 参数造成重复索引
+export const metadata: Metadata = {
+  title: "贡献者排行榜 / Contributors Rank",
+  description:
+    "Involution Hell 社区贡献者排行榜 — 按文档 commits 实时统计。谁在写、谁在维护、本周最热文档。Realtime contributor leaderboard of the Involution Hell community.",
+  alternates: { canonical: "/rank" },
+  openGraph: {
+    title: "Contributors Rank · Involution Hell",
+    description:
+      "Realtime contributor leaderboard & hottest docs in the Involution Hell community.",
+    url: "/rank",
+    type: "website",
+  },
+};
+
 import { MAINTAINERS } from "@/lib/admins";
 
 const rawRanks = leaderboardData as {
diff --git a/app/settings/page.tsx b/app/settings/page.tsx
index 12a2b488..11a7e248 100644
--- a/app/settings/page.tsx
+++ b/app/settings/page.tsx
@@ -1,10 +1,19 @@
 // 用户偏好设置页（Server Component）
 // 登录态由客户端 SettingsForm 内部的 useAuth 处理：token 存在 localStorage，服务端无法读取，
 // 所以这里不做服务端鉴权，仅负责渲染页面壳。未登录 → 客户端 router.replace 到 /login?redirect=/settings。
+import type { Metadata } from "next";
 import { Header } from "@/app/components/Header";
 import { Footer } from "@/app/components/Footer";
 import { SettingsForm } from "./SettingsForm";
 
+// SEO: 设置页仅登录用户相关，不参与搜索索引
+export const metadata: Metadata = {
+  title: "Settings",
+  description: "Customize theme, language, and AI assistant preferences.",
+  alternates: { canonical: "/settings" },
+  robots: { index: false, follow: true },
+};
+
 export default function SettingsPage() {
   return (
     <>
diff --git a/app/sitemap.ts b/app/sitemap.ts
index eefbcef6..426c08e5 100644
--- a/app/sitemap.ts
+++ b/app/sitemap.ts
@@ -20,6 +20,7 @@
 
 import type { MetadataRoute } from "next";
 import { source } from "@/lib/source";
+import leaderboard from "@/generated/site-leaderboard.json";
 
 /**
  * 从环境变量中读取的站点根 URL。
@@ -102,12 +103,34 @@ export default function sitemap(): MetadataRoute.Sitemap {
     priority: 1, // 首页是最高优先级
   };
 
-  // 4. 合并与处理
+  // 4. /rank 排行榜页（静态路由）
+  const rankEntry: MetadataRoute.Sitemap[number] = {
+    url: `${SITE_URL}/rank`,
+    changeFrequency: "daily", // 贡献排行榜每天都可能变
+    priority: 0.7,
+  };
+
+  // 5. 个人主页 /u/[githubId] — 从 build-time leaderboard JSON 枚举所有贡献者。
+  // 非贡献者 / 新注册用户的 profile 不入 sitemap（search crawler 进去也是空白，浪费 crawl budget）。
+  type LeaderboardRow = { id?: string };
+  const profileEntries: MetadataRoute.Sitemap = (
+    leaderboard as LeaderboardRow[]
+  )
+    .filter((r) => typeof r.id === "string" && /^\d+$/.test(r.id))
+    .map((r) => ({
+      url: `${SITE_URL}/u/${r.id}`,
+      changeFrequency: "weekly" as const,
+      priority: 0.5,
+    }));
+
+  // 6. 合并与处理
   const unique = new Map(docsEntries.map((e) => [e.url, e]));
 
-  // 返回合并后的数组：首页 + (去重后的文档页)
+  // 返回合并后的数组：首页 + /rank + 贡献者 profiles + (去重后的文档页)
   return [
     homeEntry,
+    rankEntry,
+    ...profileEntries,
     ...[...unique.values()].sort((a, b) => a.url.localeCompare(b.url)),
   ];
 }
diff --git a/app/u/[username]/page.tsx b/app/u/[username]/page.tsx
index 474793f3..449ac965 100644
--- a/app/u/[username]/page.tsx
+++ b/app/u/[username]/page.tsx
@@ -114,8 +114,10 @@ interface ProfileResponse {
  */
 function warnFetchProfile(message: string, details?: Record<string, unknown>) {
   const isProduction = process.env.NODE_ENV === "production";
-  const status = typeof details?.status === "number" ? details.status : undefined;
-  const success = typeof details?.success === "boolean" ? details.success : undefined;
+  const status =
+    typeof details?.status === "number" ? details.status : undefined;
+  const success =
+    typeof details?.success === "boolean" ? details.success : undefined;
   const isExpectedNotFound = status === 404 || success === false;
 
   // 生产环境仅记录需要诊断的异常场景；404 / success=false 属于预期控制流，
@@ -294,13 +296,32 @@ interface Param {
 export async function generateMetadata({ params }: Param): Promise<Metadata> {
   const { username } = await params;
   const data = await fetchProfile(username);
-  if (!data) return { title: `@${username}` };
+  if (!data) return { title: `@${username}`, robots: { index: false } };
   const displayName = data.user.displayName || data.user.username;
+  const description =
+    data.preferences?.bio ||
+    `${displayName} on Involution Hell — projects, papers, and docs contributions.`;
+  // 用 githubId 作为 canonical URL，避免 /u/github_114939201 和 /u/114939201 两个入口重复索引
+  const canonicalId = data.user.githubId ?? data.user.username;
+  const canonical = `/u/${canonicalId}`;
+  const title = `${displayName} (@${data.user.username})`;
   return {
-    title: `${displayName} (@${data.user.username})`,
-    description:
-      data.preferences?.bio ||
-      `${displayName} 在 Involution Hell 的个人主页 — 项目、论文与文档贡献。`,
+    title,
+    description,
+    alternates: { canonical },
+    openGraph: {
+      type: "profile",
+      title,
+      description,
+      url: canonical,
+      images: data.user.avatarUrl ? [{ url: data.user.avatarUrl }] : undefined,
+    },
+    twitter: {
+      card: "summary",
+      title,
+      description,
+      images: data.user.avatarUrl ? [data.user.avatarUrl] : undefined,
+    },
   };
 }
 
@@ -339,8 +360,34 @@ export default async function UserProfilePage({ params }: Param) {
     };
   });
 
+  // Person JSON-LD：让搜索引擎识别这是一个"个人档案"而不是普通页面，有机会走 knowledge panel
+  const siteUrl =
+    process.env.NEXT_PUBLIC_SITE_URL || "https://involutionhell.com";
+  const personJsonLd = {
+    "@context": "https://schema.org",
+    "@type": "Person",
+    name: user.displayName || user.username,
+    alternateName: user.username,
+    url: `${siteUrl}/u/${user.githubId ?? user.username}`,
+    ...(user.avatarUrl ? { image: user.avatarUrl } : {}),
+    ...(preferences.bio ? { description: preferences.bio } : {}),
+    ...(user.githubId
+      ? { sameAs: [`https://github.com/${user.githubId}`] }
+      : {}),
+    memberOf: {
+      "@type": "Organization",
+      name: "Involution Hell",
+      url: siteUrl,
+    },
+  };
+
   return (
     <>
+      <script
+        type="application/ld+json"
+        // eslint-disable-next-line react/no-danger
+        dangerouslySetInnerHTML={{ __html: JSON.stringify(personJsonLd) }}
+      />
       <Header />
       <main className="pt-32 pb-16 bg-[var(--background)] min-h-screen">
         <div className="max-w-7xl mx-auto px-6 lg:px-8">