vivliostyle · ogwata · Feb 2, 2026 · Feb 1, 2026 · Feb 1, 2026 · Feb 1, 2026
diff --git a/astro.config.mjs b/astro.config.mjs
@@ -2,11 +2,22 @@
 import { defineConfig } from 'astro/config';
 import sitemap from '@astrojs/sitemap';
 
+const languages = ['en', 'ja'];
+
 // https://astro.build/config
 export default defineConfig({
   site: 'https://docs.vivliostyle.org',
   output: 'static',
-  integrations: [sitemap()],
+  integrations: [sitemap({
+    filter: (page) => {
+      const url = new URL(page);
+      return languages.includes(url.pathname.split('/')[1]);
+    },
+    i18n: {
+      defaultLocale: 'en',
+      locales: Object.fromEntries(languages.map((lang) => [lang, lang])),
+    },
+  })],
   build: {
     format: 'directory',
   },

diff --git a/src/layouts/DocsLayout.astro b/src/layouts/DocsLayout.astro
@@ -12,9 +12,10 @@ interface Props {
   description?: string;
   lang?: string;
   showBreadcrumb?: boolean;
+  availableLanguages: ('en' | 'ja')[];
 }
 
-const { title, description = '', lang = 'en', showBreadcrumb = true } = Astro.props;
+const { title, description = '', lang = 'en', showBreadcrumb = true, availableLanguages = [] } = Astro.props;
 const currentPath = Astro.url.pathname;
 ---
 <!DOCTYPE html>
@@ -25,6 +26,15 @@ const currentPath = Astro.url.pathname;
   <meta name="description" content={description}>
   <title>{title} | Vivliostyle Documentation</title>
   <link rel="icon" type="image/png" href="/favicon.png">
+  <link rel="canonical" href={`${Astro.url.origin}${currentPath}`}>
+  {availableLanguages.map((language) => (
+    <link
+      rel="alternate"
+      hreflang={language}
+      href={`${Astro.url.origin}/${language}${currentPath.replace(/^\/[^/]+/, '')}`}
+    />
+  ))}
+  <link rel="sitemap" href="/sitemap-index.xml">
   <link rel="stylesheet" href="/styles/global.css">
   <!-- Prism.js syntax highlighting -->
   <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/prism/1.29.0/themes/prism.min.css" media="(prefers-color-scheme: light)">

diff --git a/src/layouts/LanguageSwitchLayout.astro b/src/layouts/LanguageSwitchLayout.astro
@@ -0,0 +1,58 @@
+---
+/**
+ * 言語切り替えレイアウト - 言語検出とリダイレクト
+ *
+ * Accept-Languageヘッダーを確認し、適切な言語ページにリダイレクト。
+ * SSRが必要な場合はクライアントサイドで処理。
+ */
+
+interface Props {
+  targetPath: string;
+  availableLanguages?: ('en' | 'ja')[];
+  defaultLanguage?: 'en' | 'ja';
+}
+
+const {
+  targetPath,
+  availableLanguages = ['en', 'ja'],
+  defaultLanguage = 'en',
+} = Astro.props;
+---
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <title>Vivliostyle Documentation</title>
+  <meta name="robots" content="noindex">
+  <link rel="canonical" href={`${Astro.url.origin}/${defaultLanguage}${targetPath}`}>
+  <link rel="stylesheet" href="/styles/global.css">
+  <script data-target-path={targetPath} data-supported-languages={availableLanguages.join(',')} data-default-language={defaultLanguage}>
+    // 言語検出とリダイレクト
+    (function() {
+      const supportedLangs = document.currentScript.getAttribute('data-supported-languages').split(',');
+      const defaultLang = document.currentScript.getAttribute('data-default-language');
+
+      // ブラウザの言語設定を取得
+      const browserLang = navigator.language || '';
+      const langCode = browserLang.split('-')[0].toLowerCase();
+
+      // サポートされている言語かチェック
+      const targetLang = supportedLangs.includes(langCode) ? langCode : defaultLang;
+
+      // リダイレクト
+      const targetPath = document.currentScript.getAttribute('data-target-path');
+      window.location.replace(`/${targetLang}${targetPath}`);
+    })();
+  </script>
+  <noscript>
+    <meta http-equiv="refresh" content={`0; url=/${defaultLanguage}${targetPath}`}>
+  </noscript>
+</head>
+<body>
+  <noscript>
+    <meta http-equiv="refresh" content={`0; url=/${defaultLanguage}${targetPath}`}>
+  </noscript>
+  <p style="font-size: 0">Welcome to the documentation. Please navigate to <a href={`/${defaultLanguage}${targetPath}`}>English documentation</a>.</p>
+</body>
+</html>
diff --git a/src/pages/[...slug].astro b/src/pages/[...slug].astro
@@ -0,0 +1,69 @@
+---
+import LanguageSwitchLayout from '../layouts/LanguageSwitchLayout.astro';
+
+export async function getStaticPaths() {
+  const languages = ['en', 'ja'] as const;
+  const pageComponents = Object.entries(
+    import.meta.glob<{
+      getStaticPaths?: () => Promise<
+        { params: { slug: string | undefined } }[]
+      >;
+    }>('./**/*.astro', { eager: true })
+  ).flatMap((it) => {
+    const [key, value] = it;
+    const { getStaticPaths } = value;
+    const matched = /^\.\/(\w+)\/(.+\/)[^/]+\.astro$/.exec(key);
+    if (!getStaticPaths || !matched) {
+      return [];
+    }
+    const [, language, path] = matched;
+    if (!languages.includes(language as (typeof languages)[number])) {
+      return [];
+    }
+    return [
+      {
+        getStaticPaths,
+        language: language as (typeof languages)[number],
+        path,
+      } as const,
+    ];
+  });
+
+  const pages = (
+    await Promise.all(
+      pageComponents.map(async ({ getStaticPaths, ...rest }) => ({
+        ...rest,
+        staticPaths: await getStaticPaths(),
+      }))
+    )
+  ).flatMap(({ staticPaths, path, language }) =>
+    staticPaths.map(({ params }) => ({
+      language,
+      slug: `${path}${params.slug ?? ''}`,
+    }))
+  );
+  const allSlugs = new Set(pages.map(({ slug }) => slug));
+  return Array.from(allSlugs).map((slug) => {
+    const availableLanguages = pages.flatMap((page) =>
+      page.slug === slug ? [page.language] : []
+    );
+    return {
+      params: { slug },
+      props: {
+        availableLanguages,
+        defaultLanguage: availableLanguages.includes('en')
+          ? 'en'
+          : availableLanguages[0],
+      },
+    };
+  });
+}
+
+const { availableLanguages, defaultLanguage } = Astro.props;
+---
+
+<LanguageSwitchLayout
+  targetPath={`/${Astro.params.slug}/`}
+  availableLanguages={availableLanguages}
+  defaultLanguage={defaultLanguage}
+/>
diff --git a/src/pages/en/cli/[...slug].astro b/src/pages/en/cli/[...slug].astro
@@ -88,7 +88,12 @@ const prevPage = currentIndex > 0 ? sortedDocs[currentIndex - 1] : null;
 const nextPage = currentIndex < sortedDocs.length - 1 ? sortedDocs[currentIndex + 1] : null;
 ---
 
-<DocsLayout title={title} description={description} lang="en">
+<DocsLayout
+  title={title}
+  description={description}
+  lang="en"
+  availableLanguages={hasJaTranslation ? ['en', 'ja'] : []}
+>
   <div slot="header" class="language-switcher-container">
     <LanguageSwitcher currentLang="en" pagePath={pagePath} hasTranslation={hasJaTranslation} />
   </div>

diff --git a/src/pages/en/index.astro b/src/pages/en/index.astro
@@ -36,7 +36,12 @@ const title = indexDoc?.data?.title || 'Welcome to Vivliostyle Documentation';
 const description = indexDoc?.data?.description || 'Official documentation for Vivliostyle';
 ---
 
-<DocsLayout title={title} description={description} lang="en">
+<DocsLayout
+  title={title}
+  description={description}
+  lang="en"
+  availableLanguages={['en', 'ja']}
+>
   <LanguageSwitcher slot="header" currentLang="en" pagePath="/" hasTranslation={true} />
   <nav slot="sidebar">
     <h3>Documentation</h3>

diff --git a/src/pages/en/reference/[...slug].astro b/src/pages/en/reference/[...slug].astro
@@ -164,11 +164,12 @@ for (let i = currentIndex + 1; i < sortedDocs.length; i++) {
 }
 ---
 
-<DocsLayout 
-  title={title} 
+<DocsLayout
+  title={title}
   description={description}
   lang="en"
   section="reference"
+  availableLanguages={hasJaTranslation ? ['en', 'ja'] : []}
 >
   <!-- Language switcher in header -->
   {hasJaTranslation && (

diff --git a/src/pages/en/reference/index.astro b/src/pages/en/reference/index.astro
@@ -20,10 +20,11 @@ const description = indexDoc?.data?.description || 'Reference documentation for
 ---
 
 <DocsLayout 
-  title={title} 
+  title={title}
   description={description}
   lang="en"
   section="reference"
+  availableLanguages={hasJaTranslation ? ['en', 'ja'] : []}
 >
   <!-- Language switcher in header -->
   {hasJaTranslation && (

diff --git a/src/pages/en/themes/[...slug].astro b/src/pages/en/themes/[...slug].astro
@@ -67,7 +67,12 @@ const prevPage = currentIndex > 0 ? sortedDocs[currentIndex - 1] : null;
 const nextPage = currentIndex < sortedDocs.length - 1 ? sortedDocs[currentIndex + 1] : null;
 ---
 
-<DocsLayout title={title} description={description} lang="en">
+<DocsLayout
+  title={title}
+  description={description}
+  lang="en"
+  availableLanguages={hasJaTranslation ? ['en', 'ja'] : []}
+>
   <div slot="header" class="language-switcher-container">
     <LanguageSwitcher currentLang="en" pagePath={pagePath} hasTranslation={hasJaTranslation} />
   </div>

diff --git a/src/pages/en/vfm/[...slug].astro b/src/pages/en/vfm/[...slug].astro
@@ -66,7 +66,12 @@ const prevPage = currentIndex > 0 ? sortedDocs[currentIndex - 1] : null;
 const nextPage = currentIndex < sortedDocs.length - 1 ? sortedDocs[currentIndex + 1] : null;
 ---
 
-<DocsLayout title={title} description={description} lang="en">
+<DocsLayout
+  title={title}
+  description={description}
+  lang="en"
+  availableLanguages={hasJaTranslation ? ['en', 'ja'] : []}
+>
   <div slot="header" class="language-switcher-container">
     <LanguageSwitcher currentLang="en" pagePath={pagePath} hasTranslation={hasJaTranslation} />
   </div>

diff --git a/src/pages/en/viewer/[...slug].astro b/src/pages/en/viewer/[...slug].astro
@@ -67,11 +67,12 @@ const prevPage = currentIndex > 0 ? sortedDocs[currentIndex - 1] : null;
 const nextPage = currentIndex < sortedDocs.length - 1 ? sortedDocs[currentIndex + 1] : null;
 ---
 
-<DocsLayout 
-  title={title} 
+<DocsLayout
+  title={title}
   description={description}
   lang="en"
   section="viewer"
+  availableLanguages={hasJaTranslation ? ['en', 'ja'] : []}
 >
   <!-- ヘッダーに言語切り替え -->
   {hasJaTranslation && (

diff --git a/src/pages/index.astro b/src/pages/index.astro
@@ -1,42 +1,5 @@
 ---
-/**
- * ルートページ - 言語検出とリダイレクト
- * 
- * Accept-Languageヘッダーを確認し、適切な言語ページにリダイレクト。
- * SSRが必要な場合はクライアントサイドで処理。
- */
+import LanguageSwitchLayout from '../layouts/LanguageSwitchLayout.astro';
 ---
-<!DOCTYPE html>
-<html lang="en">
-<head>
-  <meta charset="UTF-8">
-  <meta name="viewport" content="width=device-width, initial-scale=1.0">
-  <title>Vivliostyle Documentation</title>
-  <script>
-    // 言語検出とリダイレクト
-    (function() {
-      const supportedLangs = ['en', 'ja'];
-      const defaultLang = 'en';
-
-      // ブラウザの言語設定を取得
-      const browserLang = navigator.language || '';
-      const langCode = browserLang.split('-')[0].toLowerCase();
-
-      // サポートされている言語かチェック
-      const targetLang = supportedLangs.includes(langCode) ? langCode : defaultLang;
-
-      // リダイレクト
-      window.location.replace('/' + targetLang + '/');
-    })();
-  </script>
-  <noscript>
-    <meta http-equiv="refresh" content="0; url=/en/">
-  </noscript>
-</head>
-<body>
-  <noscript>
-    <meta http-equiv="refresh" content="0; url=/en/">
-  </noscript>
-  <p>Welcome to the documentation. Please navigate to <a href="/en/">English documentation</a>.</p>
-</body>
-</html>
+
+<LanguageSwitchLayout targetPath="/" />
diff --git a/src/pages/ja/cli/[...slug].astro b/src/pages/ja/cli/[...slug].astro
@@ -121,7 +121,12 @@ const prevPage = currentIndex > 0 ? sortedDocs[currentIndex - 1] : null;
 const nextPage = currentIndex < sortedDocs.length - 1 ? sortedDocs[currentIndex + 1] : null;
 ---
 
-<DocsLayout title={title} description={description} lang="ja">
+<DocsLayout
+  title={title}
+  description={description}
+  lang="ja"
+  availableLanguages={hasEnTranslation ? ['en', 'ja']: []}
+>
   <div slot="header" class="language-switcher-container">
     <LanguageSwitcher currentLang="ja" pagePath={pagePath} hasTranslation={hasEnTranslation} />
   </div>

diff --git a/src/pages/ja/index.astro b/src/pages/ja/index.astro
@@ -25,7 +25,12 @@ const title = indexDoc?.data?.title || 'Vivliostyle ドキュメントへよう
 const description = indexDoc?.data?.description || 'Vivliostyle公式ドキュメント';
 ---
 
-<DocsLayout title={title} description={description} lang="ja">
+<DocsLayout
+  title={title}
+  description={description}
+  lang="ja"
+  availableLanguages={['en', 'ja']}
+>
   <LanguageSwitcher slot="header" currentLang="ja" pagePath="/" hasTranslation={true} />
   <nav slot="sidebar">
     <h3>ドキュメント</h3>

diff --git a/src/pages/ja/reference/[...slug].astro b/src/pages/ja/reference/[...slug].astro
@@ -164,11 +164,12 @@ for (let i = currentIndex + 1; i < sortedDocs.length; i++) {
 }
 ---
 
-<DocsLayout 
-  title={title} 
+<DocsLayout
+  title={title}
   description={description}
   lang="ja"
   section="reference"
+  availableLanguages={hasEnTranslation ? ['en', 'ja'] : []}
 >
   <!-- ヘッダーに言語切り替え -->
   {hasEnTranslation && (

diff --git a/src/pages/ja/reference/index.astro b/src/pages/ja/reference/index.astro
@@ -19,11 +19,12 @@ const title = indexDoc?.data?.title || 'リファレンス';
 const description = indexDoc?.data?.description || 'Vivliostyle関連ドキュメントのリファレンス集';
 ---
 
-<DocsLayout 
-  title={title} 
+<DocsLayout
+  title={title}
   description={description}
   lang="ja"
   section="reference"
+  availableLanguages={hasEnTranslation ? ['en', 'ja'] : []}
 >
   <!-- ヘッダーに言語切り替え -->
   {hasEnTranslation && (

diff --git a/src/pages/ja/themes/[...slug].astro b/src/pages/ja/themes/[...slug].astro
@@ -68,7 +68,12 @@ const prevPage = currentIndex > 0 ? sortedDocs[currentIndex - 1] : null;
 const nextPage = currentIndex < sortedDocs.length - 1 ? sortedDocs[currentIndex + 1] : null;
 ---
 
-<DocsLayout title={title} description={description} lang="ja">
+<DocsLayout
+  title={title}
+  description={description}
+  lang="ja"
+  availableLanguages={hasEnTranslation ? ['en', 'ja']: []}
+>
   <div slot="header" class="language-switcher-container">
     <LanguageSwitcher currentLang="ja" pagePath={pagePath} hasTranslation={hasEnTranslation} />
   </div>