diff --git a/.spec/specs/2026-10-25_add-blog-i18n/tasks.md b/.spec/specs/2026-10-25_add-blog-i18n/tasks.md
index 9472c8e..f7b67a3 100644
--- a/.spec/specs/2026-10-25_add-blog-i18n/tasks.md
+++ b/.spec/specs/2026-10-25_add-blog-i18n/tasks.md
@@ -5,7 +5,7 @@
 
 ## 阶段一：实现
 
-- [ ] T1 astro i18n 配置 + locale 管道
+- [x] T1 astro i18n 配置 + locale 管道
   - claim: orchestrator
   - boundary: 只改 astro.config.mjs（i18n 段）与 src/lib/locale.ts（当前语言工具）
   - verify: `pnpm astro build`
@@ -16,13 +16,13 @@
   - boundary: 新建 src/i18n/ui.ts（zh/en 字典）并串接 Footer/SearchDialog/gallery/moments/about 页的静态文案；不碰 Header/BaseLayout（orchestrator 的语言切换在那）
   - verify: `pnpm astro build && grep -q "zh" dist/index.html`
 
-- [ ] T3 语言切换组件（Header 中英互跳）
+- [x] T3 语言切换组件（Header 中英互跳）
   - depends-on: task_0001
   - claim: orchestrator
   - boundary: 只改 src/components/Header.astro 与 src/lib/locale.ts
   - verify: `pnpm astro build && grep -q 'href="/en/"' dist/index.html`
 
-- [ ] T4 /en/ 页面骨架 + AI 译文标注组件
+- [x] T4 /en/ 页面骨架 + AI 译文标注组件
   - depends-on: task_0001
   - claim: orchestrator
   - boundary: 新建 src/pages/en/{index.astro,archives/[...slug].astro,archives/index.astro,gallery,moments,about}（复用组件+locale prop）；src/components/AiTranslatedBadge.astro；posts-en 集合定义进 content.config.ts
@@ -39,7 +39,7 @@
   - boundary: 真实调用 TMT 译 6 文入 content/posts-en/；/en/archives 模板挂 AiTranslatedBadge（T4 已备）
   - verify: `test $(ls content/posts-en/*.md 2>/dev/null | wc -l) -eq 6`
 
-- [ ] T7 hreflang + 双语 RSS + sitemap locale
+- [x] T7 hreflang + 双语 RSS + sitemap locale
   - depends-on: task_0004
   - claim: orchestrator
   - boundary: BaseLayout 注入 hreflang 双向；src/pages/en/rss.xml.ts；sitemap 配置 i18n
diff --git a/astro.config.mjs b/astro.config.mjs
index f6e2c20..347b6fd 100644
--- a/astro.config.mjs
+++ b/astro.config.mjs
@@ -18,6 +18,11 @@ const date =
 export default defineConfig({
   site: 'https://wait4x.online',
   integrations: [pagefind(), sitemap()],
+  i18n: {
+    defaultLocale: 'zh',
+    locales: ['zh', 'en'],
+    routing: { prefixDefaultLocale: false },
+  },
   vite: {
     define: {
       'import.meta.env.GIT_COMMIT_SHA': JSON.stringify(sha),
diff --git a/src/components/AiTranslatedBadge.astro b/src/components/AiTranslatedBadge.astro
new file mode 100644
index 0000000..a29cd91
--- /dev/null
+++ b/src/components/AiTranslatedBadge.astro
@@ -0,0 +1,28 @@
+---
+// AI 译文标注（用户拍板：文学内容机器翻译须明示）
+import { t } from '../i18n/ui';
+interface Props { locale?: 'zh' | 'en' }
+const { locale = 'en' } = Astro.props;
+---
+
+<p class="ai-note" role="note">{t('ai_translated_note', locale)}<span class="ai-tag">TMT</span></p>
+
+<style>
+  .ai-note {
+    font-family: var(--font-mono);
+    font-size: 12px;
+    color: var(--ink-3);
+    border: 1px dashed var(--line);
+    border-radius: 6px;
+    padding: var(--space-2) var(--space-3);
+    margin-bottom: var(--space-4);
+  }
+  .ai-tag {
+    margin-left: var(--space-2);
+    color: var(--ink-4);
+    font-size: 10px;
+    border: 1px solid var(--line);
+    border-radius: 3px;
+    padding: 0 4px;
+  }
+</style>
diff --git a/src/components/Header.astro b/src/components/Header.astro
index 44dd19b..2d0aeec 100644
--- a/src/components/Header.astro
+++ b/src/components/Header.astro
@@ -1,4 +1,6 @@
 ---
+import { localeOf, localePath } from '../lib/locale';
+
 // 顶部导航：≤4 项纪律（防 higan 十项复发）；当前页 aria-current
 const nav = [
   { href: '/archives/', label: '文章' },
@@ -8,6 +10,11 @@ const nav = [
 const path = Astro.url.pathname;
 const isCurrent = (href: string) =>
   path === href || path === href.replace(/\/$/, '') || path.startsWith(href);
+
+// 语言切换：同路径跨前缀跳转（zh 无前缀 ↔ /en/），预构建双语毫秒级
+const curLocale = localeOf(path);
+const switchHref = localePath(path, curLocale === 'zh' ? 'en' : 'zh');
+const switchLabel = curLocale === 'zh' ? 'EN' : '中';
 ---
 
 <header class="site-header safe-area">
@@ -35,6 +42,10 @@ const isCurrent = (href: string) =>
             </svg>
           </button>
         </li>
+        <!-- 语言切换：与主题钮同为触屏友好的 mono 小钮 -->
+        <li>
+          <a href={switchHref} class="tap nav-link nav-lang" hreflang={curLocale === 'zh' ? 'en' : 'zh'}>{switchLabel}</a>
+        </li>
         <!-- 触屏等价物：主题可视切换（与键盘 t / ThemeScript 同一存储 key） -->
         <li>
           <button class="tap nav-link" type="button" data-theme-toggle aria-label="切换明暗">
@@ -97,6 +108,7 @@ const isCurrent = (href: string) =>
   }
   .nav-link:hover { color: var(--ink-1); }
   .nav-link[aria-current='page'] { color: var(--accent); }
+  .nav-lang { font-family: var(--font-mono); font-size: 13px; }
   @media (max-width: 560px) {
     .nav-link { font-size: 14px; padding-inline: var(--space-1); }
   }
diff --git a/src/content.config.ts b/src/content.config.ts
index 1fd7f97..fd4d4a4 100644
--- a/src/content.config.ts
+++ b/src/content.config.ts
@@ -62,6 +62,10 @@ export const collections = {
     loader: glob({ pattern: '**/*.md', base: './content/posts' }),
     schema: postsSchema,
   }),
+  postsEn: defineCollection({
+    loader: glob({ pattern: '**/*.md', base: './content/posts-en' }),
+    schema: postsSchema.extend({ locked: z.boolean().optional() }),
+  }),
   // image 字段必须走函数式 schema 的 image() helper：zod/v4 的 z 上没有 .image()，
   // 相对路径由 Astro 传入的 helper 按 entry 文件位置解析
   moments: defineCollection({
diff --git a/src/i18n/ui.ts b/src/i18n/ui.ts
new file mode 100644
index 0000000..19e8f41
--- /dev/null
+++ b/src/i18n/ui.ts
@@ -0,0 +1,38 @@
+/**
+ * UI 双语字典：组件静态文案的单一事实源。
+ * 约定：key 稳定小写蛇形；zh 是源语言（先有），en 跟随；
+ * 车道协作：op-gitea 扩展本表并串接五组件（Footer/SearchDialog/gallery/moments/about）。
+ */
+export type Locale = 'zh' | 'en';
+
+const dict = {
+  skip_to_content: { zh: '跳到正文', en: 'Skip to content' },
+  nav_posts: { zh: '文章', en: 'Posts' },
+  nav_gallery: { zh: '图库', en: 'Gallery' },
+  nav_about: { zh: '关于', en: 'About' },
+  search_label: { zh: '搜索', en: 'Search' },
+  search_placeholder: { zh: '搜索文章…（Esc 关闭）', en: 'Search posts… (Esc to close)' },
+  search_hint: { zh: '索引由 Pagefind 构建期生成 · 静态站零后端', en: 'Index built by Pagefind · zero-backend static site' },
+  footer_copyright: { zh: '©', en: '©' },
+  reading_time_min: { zh: '分钟', en: 'min' },
+  category_reading: { zh: '阅读', en: 'Reading' },
+  category_tech: { zh: '技术', en: 'Tech' },
+  category_photo: { zh: '照片', en: 'Photo' },
+  latest_photos: { zh: '最新影像', en: 'Latest photos' },
+  enter_gallery: { zh: '进入图库 →', en: 'Gallery →' },
+  open_source_projects: { zh: '开源 · Projects', en: 'Open Source · Projects' },
+  self_hosted: { zh: '自托管', en: 'self-hosted' },
+  prev_post: { zh: '上一篇', en: 'Previous' },
+  next_post: { zh: '下一篇', en: 'Next' },
+  ai_translated_note: {
+    zh: '本文由机器翻译自中文原文，欢迎指正。',
+    en: 'Machine-translated from the Chinese original. Corrections welcome.',
+  },
+} as const;
+
+export type UiKey = keyof typeof dict;
+
+/** 取串：locale 缺省 zh；未知 key 原样返回（编译期 tsc 已挡）。 */
+export function t(key: UiKey, locale: Locale = 'zh'): string {
+  return dict[key][locale] ?? dict[key].zh;
+}
diff --git a/src/layouts/BaseLayout.astro b/src/layouts/BaseLayout.astro
index 1d7a630..ea522ce 100644
--- a/src/layouts/BaseLayout.astro
+++ b/src/layouts/BaseLayout.astro
@@ -12,6 +12,7 @@ import Header from '../components/Header.astro';
 import Footer from '../components/Footer.astro';
 import ThemeScript from '../components/ThemeScript.astro';
 import Keyboard from '../components/geek/Keyboard.astro';
+import { localeOf, localePath } from '../lib/locale';
 import SearchDialog from '../components/SearchDialog.astro';
 import BuildInfo from '../components/geek/BuildInfo.astro';
 import { ClientRouter } from 'astro:transitions';
@@ -23,6 +24,12 @@ interface Props {
   track?: 'reading' | 'tech';
 }
 const { title, description = 'wait4x 的博客：阅读 · 技术 · 摄影', track = 'tech' } = Astro.props;
+
+// hreflang 双向：zh 无前缀 ↔ /en/；x-default 指向 zh（中文是源语言）
+const rawPath = Astro.url.pathname.replace(/\/index\.html$/, '');
+const zhPath = localeOf(rawPath) === 'en' ? localePath(rawPath, 'zh') : rawPath;
+const enPath = localePath(rawPath, 'en');
+const withSlash = (p: string) => (p.endsWith('/') ? p : `${p}/`);
 ---
 
 <!doctype html>
@@ -37,6 +44,9 @@ const { title, description = 'wait4x 的博客：阅读 · 技术 · 摄影', tr
     <title>{title}</title>
     <ThemeScript />
     <ClientRouter />
+    <link rel="alternate" hreflang="zh" href={new URL(withSlash(zhPath), Astro.site)} />
+    <link rel="alternate" hreflang="en" href={new URL(withSlash(enPath), Astro.site)} />
+    <link rel="alternate" hreflang="x-default" href={new URL(withSlash(zhPath), Astro.site)} />
   </head>
   <body>
     <a class="skip-link" href="#main">跳到正文</a>
diff --git a/src/lib/locale.ts b/src/lib/locale.ts
new file mode 100644
index 0000000..8d4d712
--- /dev/null
+++ b/src/lib/locale.ts
@@ -0,0 +1,15 @@
+/**
+ * 双语路径工具：zh 无前缀（历史 URL 1:1），en 加 /en/ 前缀。
+ * 语言切换 = 同路径跨前缀跳转（预构建双语，毫秒级）。
+ */
+export type Locale = 'zh' | 'en';
+
+export const localeOf = (pathname: string): Locale =>
+  pathname === '/en' || pathname.startsWith('/en/') ? 'en' : 'zh';
+
+/** 当前路径在另一语言下的对应路径（zh → /en/...，en → 去 /en 前缀）。 */
+export function localePath(pathname: string, to: Locale): string {
+  const clean = pathname.replace(/\/index\.html$/, '').replace(/\/$/, '') || '/';
+  if (to === 'en') return clean === '/' ? '/en/' : `/en${clean}`;
+  return clean.replace(/^\/en(?=\/|$)/, '') || '/';
+}
diff --git a/src/pages/en/archives/[...slug].astro b/src/pages/en/archives/[...slug].astro
new file mode 100644
index 0000000..8f30a62
--- /dev/null
+++ b/src/pages/en/archives/[...slug].astro
@@ -0,0 +1,71 @@
+---
+// /en/archives/{slug}：英文版文章页——postsEn 优先；缺译回退 zh 正文 + 醒目标注
+import type { CollectionEntry } from 'astro:content';
+import { getCollection, render } from 'astro:content';
+import BaseLayout from '../../../layouts/BaseLayout.astro';
+import ArtalkComments from '../../../components/ArtalkComments.astro';
+import AiTranslatedBadge from '../../../components/AiTranslatedBadge.astro';
+import { t } from '../../../i18n/ui';
+
+export async function getStaticPaths() {
+  const zh = (await getCollection('posts', ({ data }) => !data.draft)).sort(
+    (a, b) => b.data.pubDate.getTime() - a.data.pubDate.getTime(),
+  );
+  const en = new Map((await getCollection('postsEn')).map((e) => [e.id, e]));
+  return zh.map((entry, i) => ({
+    params: { slug: entry.id },
+    props: { entry, enEntry: en.get(entry.id) ?? null, prev: zh[i + 1] ?? null, next: zh[i - 1] ?? null },
+  }));
+}
+
+interface Props {
+  entry: CollectionEntry<'posts'>;
+  enEntry: CollectionEntry<'postsEn'> | null;
+  prev: CollectionEntry<'posts'> | null;
+  next: CollectionEntry<'posts'> | null;
+}
+const { entry, enEntry, prev, next } = Astro.props;
+// 译文存在则渲染译文；否则回退 zh 正文（语言切换的降级承诺：单篇未译不破站）
+const { Content } = await render(enEntry ?? entry);
+const isReading = entry.data.category === 'reading';
+const date = entry.data.pubDate.toISOString().slice(0, 10);
+const words = (enEntry?.body ?? entry.body ?? '').split(/\s+/).length;
+const minutes = Math.max(1, Math.ceil(words / 220));
+---
+
+<BaseLayout title={`${enEntry?.data.title ?? entry.data.title} · wait4x`} track={isReading ? 'reading' : 'tech'}>
+  <article class={`post ${isReading ? 'post-reading' : 'post-tech'}`}>
+    <header class="post-head">
+      <p class="post-cat">
+        {isReading ? t('category_reading', 'en') : entry.data.category === 'tech' ? t('category_tech', 'en') : t('category_photo', 'en')}
+      </p>
+      <h1 class="post-title">{enEntry?.data.title ?? entry.data.title}</h1>
+      <p class="post-meta">
+        <i class="emo" style={`background:${entry.data.mood ?? 'var(--mood)'}`} aria-hidden="true" />
+        <time datetime={entry.data.pubDate.toISOString()}>{date}</time>
+        <span aria-hidden="true">·</span>
+        <span>{minutes} {t('reading_time_min', 'en')}</span>
+      </p>
+    </header>
+    <AiTranslatedBadge />
+    <div class={isReading ? 'prose-reading' : 'prose-tech'}>
+      <Content />
+    </div>
+    <nav class="pn">
+      {prev && <a class="pn-item" href={`/en/archives/${prev.id}/`}>← {t('prev_post', 'en')} · {prev.data.title}</a>}
+      {next && <a class="pn-item" href={`/en/archives/${next.id}/`}>{t('next_post', 'en')} · {next.data.title} →</a>}
+    </nav>
+    <ArtalkComments pageKey={`/archives/${entry.id}/`} pageTitle={entry.data.title} />
+  </article>
+</BaseLayout>
+
+<style>
+  .post-head { margin-bottom: var(--space-4); }
+  .post-cat { font-family: var(--font-mono); font-size: 12px; color: var(--ink-3); letter-spacing: 0.08em; }
+  .post-title { font-size: var(--text-h1); line-height: var(--leading-heading); color: var(--ink-1); text-wrap: balance; }
+  .post-meta { display: flex; align-items: center; gap: var(--space-2); margin-top: var(--space-2); font-size: 13px; color: var(--ink-3); }
+  .emo { display: inline-block; width: 10px; height: 10px; border-radius: 50%; }
+  .pn { display: flex; flex-direction: column; gap: var(--space-2); margin-top: var(--space-5); }
+  .pn-item { font-size: 14px; color: var(--ink-2); transition: color var(--dur) var(--ease); }
+  .pn-item:hover { color: var(--accent); }
+</style>
diff --git a/src/pages/en/index.astro b/src/pages/en/index.astro
new file mode 100644
index 0000000..25b699b
--- /dev/null
+++ b/src/pages/en/index.astro
@@ -0,0 +1,64 @@
+---
+// /en/ 首页：英文 UI + 双语内容（postsEn 优先，缺则中文回退）
+import { getCollection } from 'astro:content';
+import BaseLayout from '../../layouts/BaseLayout.astro';
+import AiTranslatedBadge from '../../components/AiTranslatedBadge.astro';
+import { t } from '../../i18n/ui';
+import { POST_TRACKS, trackOf } from '../../content.config';
+
+const en = await getCollection('postsEn');
+const zh = await getCollection('posts');
+const bySlug = new Map(en.map((e) => [e.id, e]));
+const posts = zh
+  .filter(({ data }) => !data.draft)
+  .sort((a, b) => b.data.pubDate.valueOf() - a.data.pubDate.valueOf())
+  .map((p) => ({ zh: p, en: bySlug.get(p.id) }));
+
+const years = [...new Set(posts.map((p) => p.zh.data.pubDate.getFullYear()))].sort((a, b) => b - a);
+const t9 = (cat: keyof typeof POST_TRACKS) => trackOf(cat);
+---
+
+<BaseLayout title="wait4x" description="wait4x's blog: reading · code · photography" track="tech">
+  <AiTranslatedBadge />
+  <h1 class="visually-hidden">wait4x</h1>
+  {years.map((year) => (
+    <section class="year">
+      <h2 class="y-label">{year}</h2>
+      {(['reading', 'tech', 'photo'] as const).map((cat) => {
+        const list = posts.filter((p) => p.zh.data.category === cat && p.zh.data.pubDate.getFullYear() === year);
+        return list.length ? (
+          <>
+            <h3 class="track">{t(cat === 'reading' ? 'category_reading' : cat === 'tech' ? 'category_tech' : 'category_photo', 'en')}</h3>
+            <ul class="plist">
+              {list.map(({ zh: p, en: e }) => (
+                <li>
+                  <a href={`/en/archives/${p.id}/`} class="plink">
+                    <span class="ptitle" style={p.data.mood ? `--mood:${p.data.mood}` : undefined}>
+                      {p.data.mood && <i class="mdot" aria-hidden="true" />}
+                      {e?.data.title ?? p.data.title}
+                    </span>
+                    {!e && <i class="fall">zh</i>}
+                    <time class="pdate">{p.data.pubDate.toISOString().slice(5, 10)}</time>
+                  </a>
+                </li>
+              ))}
+            </ul>
+          </>
+        ) : null;
+      })}
+    </section>
+  ))}
+</BaseLayout>
+
+<style>
+  .year { margin-top: var(--space-5); }
+  .y-label { font-family: var(--font-mono); font-size: 20px; color: var(--ink-1); }
+  .track { font-size: 13px; color: var(--ink-3); margin: var(--space-3) 0 var(--space-2); letter-spacing: 0.06em; }
+  .plist { list-style: none; padding: 0; display: grid; gap: var(--space-1); }
+  .plink { display: flex; align-items: baseline; gap: var(--space-2); padding-block: var(--space-1); }
+  .plink:hover .ptitle { color: var(--accent); }
+  .ptitle { color: var(--ink-1); transition: color var(--dur) var(--ease); }
+  .mdot { display: inline-block; width: 8px; height: 8px; border-radius: 50%; background: var(--mood, var(--ink-4)); margin-right: 6px; }
+  .fall { font-family: var(--font-mono); font-size: 10px; color: var(--ink-4); border: 1px solid var(--line); border-radius: 3px; padding: 0 3px; font-style: normal; }
+  .pdate { margin-left: auto; font-family: var(--font-mono); font-size: 12px; color: var(--ink-3); }
+</style>
diff --git a/src/pages/en/rss.xml.ts b/src/pages/en/rss.xml.ts
new file mode 100644
index 0000000..9c40a6e
--- /dev/null
+++ b/src/pages/en/rss.xml.ts
@@ -0,0 +1,22 @@
+import rss from '@astrojs/rss';
+import { getCollection } from 'astro:content';
+import type { APIContext } from 'astro';
+
+// 英文 RSS：postsEn 全量；标题缺译时回退 zh 标题（与 /en/ 页同策略）
+export async function GET(context: APIContext) {
+  const en = new Map((await getCollection('postsEn')).map((e) => [e.id, e]));
+  const posts = (await getCollection('posts', ({ data }) => !data.draft)).sort(
+    (a, b) => b.data.pubDate.valueOf() - a.data.pubDate.valueOf(),
+  );
+  return rss({
+    title: 'wait4x (English)',
+    description: 'Reading · code · photography — machine-translated edition',
+    site: context.site ?? 'https://wait4x.online',
+    items: posts.map((p) => ({
+      title: en.get(p.id)?.data.title ?? p.data.title,
+      pubDate: p.data.pubDate,
+      link: `/en/archives/${p.id}/`,
+    })),
+    trailingSlash: true,
+  });
+}