fix(search): include English pages in the en search index

source.getPages() without a locale argument only returns default-locale
(zh) pages, so the static /search.en.json index has been empty since the
i18n split. Enumerate pages with getPages("en") and classify English
pages by the .en.md(x) file suffix in addition to lang frontmatter, so
translations missing lang: en are indexed and excluded from the zh shard.

Author: colin-zheng

app/search.en.json/route.ts

@@ -5,12 +5,12 @@ import { pageToIndex, isEnglishPage } from "@/lib/search-index";
 export const dynamic = "force-static";
 
 /**
- * 英文搜索索引分片：只包含 lang==="en" 的翻译版文档，
+ * 英文搜索索引分片：按 frontmatter 或 .en 文件名识别翻译版文档，
  * 用 Orama 默认英文分词（无需 mandarin tokenizer）。
  */
 const api = createSearchAPI("advanced", {
   indexes: () =>
-    Promise.all(source.getPages().filter(isEnglishPage).map(pageToIndex)),
+    Promise.all(source.getPages("en").filter(isEnglishPage).map(pageToIndex)),
   language: "english",
   search: {
     threshold: 0.3,

lib/search-index.ts

@@ -39,9 +39,9 @@ export async function pageToIndex(page: Page): Promise<AdvancedIndex> {
 
 /**
  * 判断一个 fumadocs 页面是否为英文翻译版。
- * 翻译版 frontmatter 会声明 `lang: "en"` 且通常 `translatedFrom: "zh"`。
+ * 兼容 frontmatter 语言标记和 Fumadocs 保留的原始 source path。
  */
-export function isEnglishPage(page: Page): boolean {
+export function isEnglishPage(page: { data: unknown; path: string }): boolean {
   const lang = (page.data as PageData).lang;
-  return lang === "en";
+  return lang === "en" || /\.en\.mdx?$/i.test(page.path);
 }

tests/search-index-locale.test.ts

@@ -0,0 +1,26 @@
+import { describe, expect, it, vi } from "vitest";
+
+vi.mock("@/lib/source", () => ({ source: { getPages: () => [] } }));
+
+import { isEnglishPage } from "@/lib/search-index";
+
+describe("search index locale classification", () => {
+  it("classifies English source filenames even without lang frontmatter", () => {
+    expect(
+      isEnglishPage({
+        path: "learn/cs/data-structures/array/index.en.mdx",
+        data: {},
+      }),
+    ).toBe(true);
+    expect(isEnglishPage({ path: "career/example.en.md", data: {} })).toBe(
+      true,
+    );
+    expect(isEnglishPage({ path: "career/example.md", data: {} })).toBe(false);
+  });
+
+  it("retains explicit lang frontmatter classification", () => {
+    expect(
+      isEnglishPage({ path: "career/legacy.mdx", data: { lang: "en" } }),
+    ).toBe(true);
+  });
+});