diff --git a/app/docs/[...slug]/page.tsx b/app/docs/[...slug]/page.tsx
index 960c092..ab699a1 100644
--- a/app/docs/[...slug]/page.tsx
+++ b/app/docs/[...slug]/page.tsx
@@ -18,6 +18,7 @@ import { PageFeedback } from "@/app/components/PageFeedback";
 import { DocHistoryPanel } from "@/app/components/DocHistoryPanel";
 import { DocShareButton } from "@/app/components/DocShareButton";
 import { cookies } from "next/headers";
+import { type PageData } from "@/app/types/doc";
 // Extract clean text content from MDX - no longer used on client/page side
 // content fetching moved to API route for performance
 
@@ -51,7 +52,7 @@ function getPageWithLocale(
     return { page: originalPage, isFallback: false };
 
   const originalLang =
-    (originalPage?.data as { lang?: string } | undefined)?.lang ?? null;
+    (originalPage?.data as PageData | undefined)?.lang ?? null;
 
   // 已经是目标语言，直接返回
   if (originalLang === locale) return { page: originalPage, isFallback: false };
@@ -83,11 +84,8 @@ export default async function DocPage({ params }: Param) {
 
   // 统一通过工具函数生成 Edit 链接，内部已处理中文目录编码
   const editUrl = buildDocsEditUrl(page.path);
-  const docIdFromPage =
-    (page.data as { docId?: string; frontmatter?: { docId?: string } })
-      ?.docId ??
-    (page.data as { docId?: string; frontmatter?: { docId?: string } })
-      ?.frontmatter?.docId;
+  const data = page.data as PageData;
+  const docIdFromPage = data.docId ?? data.frontmatter?.docId;
 
   const contributorsEntry =
     getDocContributorsByPath(page.file.path) ||
diff --git a/app/sitemap.ts b/app/sitemap.ts
index 85cc8db..262722b 100644
--- a/app/sitemap.ts
+++ b/app/sitemap.ts
@@ -24,36 +24,12 @@ import leaderboard from "@/generated/site-leaderboard.json";
 // SITE_URL 由 lib/site-url.ts 统一提供（从 NEXT_PUBLIC_SITE_URL 读 + 归一化），
 // 这里和 app/robots.ts 共用一份，避免两边 drift。
 import { SITE_URL } from "@/lib/site-url";
+import { type PageData, type DateLike } from "@/app/types/doc";
 
 /** * 定义 `source.getPages()` 返回的单个页面对象的类型别名
  */
 type SourcePage = ReturnType<typeof source.getPages>[number];
 
-/** * 定义可以被解析为日期的宽松类型
- */
-type DateLike = string | number | Date | undefined | null;
-
-/**
- * (FIX) 定义一个用于 page.data 的基础类型，
- * 以避免在 isDraftOrHidden 和 extractDateFromPage 中使用 'any'。
- */
-type PageData = {
-  date?: DateLike;
-  updated?: DateLike;
-  updatedAt?: DateLike;
-  lastUpdated?: DateLike;
-  draft?: boolean;
-  hidden?: boolean;
-  frontmatter?: {
-    date?: DateLike;
-    updated?: DateLike;
-    updatedAt?: DateLike;
-    lastUpdated?: DateLike;
-    draft?: boolean;
-    hidden?: boolean;
-  };
-};
-
 /**
  * Next.js 会调用的默认导出函数，用于生成整个站点的 Sitemap。
  * * @returns {MetadataRoute.Sitemap} 一个包含所有站点地图条目的数组。
diff --git a/app/types/doc.ts b/app/types/doc.ts
new file mode 100644
index 0000000..557c216
--- /dev/null
+++ b/app/types/doc.ts
@@ -0,0 +1,46 @@
+import type { StructuredData } from "fumadocs-core/mdx-plugins";
+
+/**
+ * 定义可以被解析为日期的宽松类型
+ */
+export type DateLike = string | number | Date | undefined | null;
+
+/**
+ * 定义用于 page.data 的基础类型，
+ * 包含 Fumadocs 自动生成的字段以及常见的前置元数据 (frontmatter)。
+ */
+export interface PageData {
+  title?: string;
+  description?: string;
+  date?: DateLike;
+  updated?: DateLike;
+  updatedAt?: DateLike;
+  lastUpdated?: DateLike;
+  draft?: boolean;
+  hidden?: boolean;
+  docId?: string;
+  lang?: string;
+  structuredData?: StructuredData;
+  load?: () => Promise<{ structuredData: StructuredData }>;
+  /**
+   * 允许访问 frontmatter 原始对象（Fumadocs 默认会将字段打平到 data 根部，
+   * 但部分逻辑可能仍显式访问 .frontmatter）。
+   */
+  frontmatter?: {
+    title?: string;
+    description?: string;
+    date?: DateLike;
+    updated?: DateLike;
+    updatedAt?: DateLike;
+    lastUpdated?: DateLike;
+    draft?: boolean;
+    hidden?: boolean;
+    docId?: string;
+    lang?: string;
+    [key: string]: unknown;
+  };
+  // 故意不挂顶层 [key: string]: unknown 索引签名 —— Fumadocs 的 page.data 由
+  // zod DocOut 推出，没有 index signature；如果在 PageData 上挂一个，as PageData
+  // 会触发 TS2352 "neither type sufficiently overlaps"。所有需要的字段都已
+  // 在上面显式声明；真要拓展加新字段，往这里加显式 ? 字段，别走 escape hatch。
+}
diff --git a/lib/search-index.ts b/lib/search-index.ts
index f0af15f..c76198c 100644
--- a/lib/search-index.ts
+++ b/lib/search-index.ts
@@ -4,26 +4,16 @@ import type { AdvancedIndex } from "fumadocs-core/search/server";
 import type { StructuredData } from "fumadocs-core/mdx-plugins";
 import { source } from "@/lib/source";
 import { basename, extname } from "path";
+import { type PageData } from "@/app/types/doc";
 
 type Page = ReturnType<typeof source.getPages>[number];
 
-/**
- * fumadocs page.data 在构建产物里的 runtime shape。
- * 老路径：structuredData 直接 inline；新路径：通过 load() 异步拉。
- */
-interface PageDataShape {
-  structuredData?: StructuredData;
-  load?: () => Promise<{ structuredData: StructuredData }>;
-  title?: string;
-  description?: string;
-}
-
 /**
  * 把一个 fumadocs 页面转成 Orama 索引项（复用 fumadocs-core 默认实现逻辑），
  * 单独抽出来是因为我们需要分片（zh / en），用 createSearchAPI 手动传 indexes。
  */
 export async function pageToIndex(page: Page): Promise<AdvancedIndex> {
-  const data = page.data as PageDataShape;
+  const data = page.data as PageData;
 
   let structuredData: StructuredData | undefined;
   if (data.structuredData) {
@@ -52,6 +42,6 @@ export async function pageToIndex(page: Page): Promise<AdvancedIndex> {
  * 翻译版 frontmatter 会声明 `lang: "en"` 且通常 `translatedFrom: "zh"`。
  */
 export function isEnglishPage(page: Page): boolean {
-  const lang = (page.data as { lang?: string }).lang;
+  const lang = (page.data as PageData).lang;
   return lang === "en";
 }