diff --git a/src/_locales/en/messages.json b/src/_locales/en/messages.json
index 986ec37..0718c25 100644
--- a/src/_locales/en/messages.json
+++ b/src/_locales/en/messages.json
@@ -14,7 +14,6 @@
 
   "settingsTitle": { "message": "Settings" },
   "language": { "message": "Language" },
-  "langFollowBrowser": { "message": "Follow browser" },
   "openSourced": { "message": "It's open sourced!" },
   "viewOnGithub": { "message": "View on GitHub" },
   "tokenLabel": { "message": "GitHub Personal Access Token" },
diff --git a/src/_locales/zh_CN/messages.json b/src/_locales/zh_CN/messages.json
index 57c124f..1e29a18 100644
--- a/src/_locales/zh_CN/messages.json
+++ b/src/_locales/zh_CN/messages.json
@@ -14,7 +14,6 @@
 
   "settingsTitle": { "message": "设置" },
   "language": { "message": "语言" },
-  "langFollowBrowser": { "message": "跟随浏览器" },
   "openSourced": { "message": "本项目已开源！" },
   "viewOnGithub": { "message": "在 GitHub 上查看" },
   "tokenLabel": { "message": "GitHub 个人访问令牌" },
@@ -34,7 +33,7 @@
   "groupHome": { "message": "首页" },
   "groupPRsIssues": { "message": "PR 和 Issue" },
   "groupPRDetails": { "message": "PR 详情" },
-  "groupCommits": { "message": "提交" },
+  "groupCommits": { "message": "Commits" },
   "groupRepository": { "message": "仓库" },
 
   "featBetterTopReposName": { "message": "增强的热门仓库" },
@@ -67,17 +66,17 @@
   },
   "featPrCollapseExpandName": { "message": "折叠/展开所有文件" },
   "featPrCollapseExpandDesc": {
-    "message": "在 PR、提交和对比页面添加一个折叠或展开所有文件差异的按钮。"
+    "message": "在 PR、Commit 和对比页面添加一个折叠或展开所有文件差异的按钮。"
   },
-  "featCommitTagsName": { "message": "提交标签" },
+  "featCommitTagsName": { "message": "Commit Tags" },
   "featCommitTagsDesc": {
-    "message": "在提交列表页显示 git 标签，便于识别。"
+    "message": "在 Commits 列表页显示 git tags，便于识别。"
   },
-  "featCommitDiffStatsName": { "message": "提交差异统计" },
+  "featCommitDiffStatsName": { "message": "Commit 差异统计" },
   "featCommitDiffStatsDesc": {
-    "message": "在提交列表页显示新增、删除行数和文件数（如 +223 −114 · 5 files）。需要令牌。"
+    "message": "在 Commits 列表页显示新增、删除行数和文件数（如 +223 −114 · 5 files）。需要令牌。"
   },
-  "featReleaseTabName": { "message": "发布标签页" },
+  "featReleaseTabName": { "message": "Releases 标签页" },
   "featReleaseTabDesc": {
     "message": "在仓库导航栏添加一个 Releases 标签页，方便快速访问。"
   },
@@ -100,7 +99,7 @@
   "saveFailed": { "message": "保存失败" },
   "saved": { "message": "已保存！" },
 
-  "releases": { "message": "发布" },
+  "releases": { "message": "Releases" },
   "approveNow": { "message": "立即批准" },
   "approveDialogTitle": { "message": "批准此 Pull Request？" },
   "approveCommentPlaceholder": { "message": "添加评论（可选）" },
@@ -113,7 +112,7 @@
   },
 
   "commitTagTitle": {
-    "message": "标签：$name$",
+    "message": "Tag: $name$",
     "placeholders": { "name": { "content": "$1", "example": "v1.0.0" } }
   },
   "copied": { "message": "已复制！" },
@@ -122,13 +121,13 @@
   "pinRepository": { "message": "置顶仓库" },
   "unpinRepository": { "message": "取消置顶" },
 
-  "watchers": { "message": "关注者" },
-  "forks": { "message": "复刻" },
-  "stargazers": { "message": "星标用户" },
+  "watchers": { "message": "Watchers" },
+  "forks": { "message": "Forks" },
+  "stargazers": { "message": "Stargazers" },
   "viewAll": { "message": "查看全部" },
-  "noWatchers": { "message": "暂无关注者" },
-  "noStargazers": { "message": "暂无星标用户" },
-  "noForks": { "message": "暂无复刻" },
+  "noWatchers": { "message": "暂无 Watchers" },
+  "noStargazers": { "message": "暂无 Stargazers" },
+  "noForks": { "message": "暂无 Forks" },
   "failedToLoad": { "message": "加载失败" },
 
   "collapseTree": { "message": "折叠目录树" },
diff --git a/src/_locales/zh_TW/messages.json b/src/_locales/zh_TW/messages.json
index 12e2575..ab573c6 100644
--- a/src/_locales/zh_TW/messages.json
+++ b/src/_locales/zh_TW/messages.json
@@ -14,7 +14,6 @@
 
   "settingsTitle": { "message": "設定" },
   "language": { "message": "語言" },
-  "langFollowBrowser": { "message": "跟隨瀏覽器" },
   "openSourced": { "message": "本專案已開源！" },
   "viewOnGithub": { "message": "在 GitHub 上查看" },
   "tokenLabel": { "message": "GitHub 個人存取權杖" },
@@ -34,7 +33,7 @@
   "groupHome": { "message": "首頁" },
   "groupPRsIssues": { "message": "PR 和 Issue" },
   "groupPRDetails": { "message": "PR 詳情" },
-  "groupCommits": { "message": "提交" },
+  "groupCommits": { "message": "Commits" },
   "groupRepository": { "message": "儲存庫" },
 
   "featBetterTopReposName": { "message": "增強的熱門儲存庫" },
@@ -67,17 +66,17 @@
   },
   "featPrCollapseExpandName": { "message": "摺疊/展開所有檔案" },
   "featPrCollapseExpandDesc": {
-    "message": "在 PR、提交和比較頁面新增一個摺疊或展開所有檔案差異的按鈕。"
+    "message": "在 PR、Commit 和比較頁面新增一個摺疊或展開所有檔案差異的按鈕。"
   },
-  "featCommitTagsName": { "message": "提交標籤" },
+  "featCommitTagsName": { "message": "Commit Tags" },
   "featCommitTagsDesc": {
-    "message": "在提交清單頁顯示 git 標籤，便於識別。"
+    "message": "在 Commits 清單頁顯示 git tags，便於識別。"
   },
-  "featCommitDiffStatsName": { "message": "提交差異統計" },
+  "featCommitDiffStatsName": { "message": "Commit 差異統計" },
   "featCommitDiffStatsDesc": {
-    "message": "在提交清單頁顯示新增、刪除行數和檔案數（如 +223 −114 · 5 files）。需要權杖。"
+    "message": "在 Commits 清單頁顯示新增、刪除行數和檔案數（如 +223 −114 · 5 files）。需要權杖。"
   },
-  "featReleaseTabName": { "message": "發佈分頁" },
+  "featReleaseTabName": { "message": "Releases 分頁" },
   "featReleaseTabDesc": {
     "message": "在儲存庫導覽列新增一個 Releases 分頁，方便快速存取。"
   },
@@ -100,7 +99,7 @@
   "saveFailed": { "message": "儲存失敗" },
   "saved": { "message": "已儲存！" },
 
-  "releases": { "message": "發佈" },
+  "releases": { "message": "Releases" },
   "approveNow": { "message": "立即核准" },
   "approveDialogTitle": { "message": "核准此 Pull Request？" },
   "approveCommentPlaceholder": { "message": "新增留言（選填）" },
@@ -113,7 +112,7 @@
   },
 
   "commitTagTitle": {
-    "message": "標籤：$name$",
+    "message": "Tag: $name$",
     "placeholders": { "name": { "content": "$1", "example": "v1.0.0" } }
   },
   "copied": { "message": "已複製！" },
@@ -122,13 +121,13 @@
   "pinRepository": { "message": "置頂儲存庫" },
   "unpinRepository": { "message": "取消置頂" },
 
-  "watchers": { "message": "關注者" },
-  "forks": { "message": "復刻" },
-  "stargazers": { "message": "星標使用者" },
+  "watchers": { "message": "Watchers" },
+  "forks": { "message": "Forks" },
+  "stargazers": { "message": "Stargazers" },
   "viewAll": { "message": "查看全部" },
-  "noWatchers": { "message": "尚無關注者" },
-  "noStargazers": { "message": "尚無星標使用者" },
-  "noForks": { "message": "尚無復刻" },
+  "noWatchers": { "message": "尚無 Watchers" },
+  "noStargazers": { "message": "尚無 Stargazers" },
+  "noForks": { "message": "尚無 Forks" },
   "failedToLoad": { "message": "載入失敗" },
 
   "collapseTree": { "message": "摺疊目錄樹" },
diff --git a/src/content.ts b/src/content.ts
index 133f7c4..3a44014 100644
--- a/src/content.ts
+++ b/src/content.ts
@@ -128,7 +128,7 @@ if (isExtensionValid()) {
     if (area !== "local") return;
     // Picked-up on the next injection/navigation; a refresh re-renders all text.
     if (LOCALE_KEY in changes) {
-      setLocale((changes[LOCALE_KEY].newValue as LocalePref) ?? "auto");
+      setLocale((changes[LOCALE_KEY].newValue as LocalePref) ?? "en");
     }
     for (const key of FEATURE_KEYS) {
       if (!(key in changes)) continue;
diff --git a/src/lib/i18n.test.ts b/src/lib/i18n.test.ts
index 1749791..ac08dcc 100644
--- a/src/lib/i18n.test.ts
+++ b/src/lib/i18n.test.ts
@@ -15,7 +15,6 @@ describe("i18n", () => {
     setLocale("zh_CN");
     expect(t("approveNow")).toBe("立即批准");
     expect(t("settingsTitle")).toBe("设置");
-    expect(t("langFollowBrowser")).toBe("跟随浏览器");
   });
 
   it("switches to Traditional Chinese via setLocale", () => {
@@ -32,7 +31,15 @@ describe("i18n", () => {
       "1,234 additions, 56 deletions across 3 files",
     );
     setLocale("zh_CN");
-    expect(t("commitTagTitle", "v1.0.0")).toBe("标签：v1.0.0");
+    expect(t("commitTagTitle", "v1.0.0")).toBe("Tag: v1.0.0");
+  });
+
+  it("falls back to English for a legacy/unknown preference", () => {
+    // "auto" was a valid preference before we dropped browser auto-detection;
+    // an existing user may still have it stored. It must resolve to English.
+    setLocale("auto" as unknown as Parameters<typeof setLocale>[0]);
+    expect(t("settingsTitle")).toBe("Settings");
+    expect(t("approveNow")).toBe("approve now");
   });
 
   it("returns empty string for an unknown key", () => {
diff --git a/src/lib/i18n.ts b/src/lib/i18n.ts
index 928389c..9c829f1 100644
--- a/src/lib/i18n.ts
+++ b/src/lib/i18n.ts
@@ -1,8 +1,9 @@
 // Lightweight i18n that, unlike chrome.i18n (which is locked to the browser UI
 // locale), supports an in-extension manual language override stored in
-// chrome.storage.local. Catalogs are bundled so t() stays synchronous; the
-// active locale is resolved once from the stored preference (default: follow
-// the browser locale) and can be changed at runtime via setLocale().
+// chrome.storage.local. Catalogs are bundled so t() stays synchronous. The
+// active locale defaults to English for everyone; we deliberately do NOT
+// auto-detect the browser locale. Users opt into another language explicitly
+// on the options page, and the choice can be applied at runtime via setLocale().
 import enMessages from "../_locales/en/messages.json";
 import zhCNMessages from "../_locales/zh_CN/messages.json";
 import zhTWMessages from "../_locales/zh_TW/messages.json";
@@ -19,52 +20,43 @@ const CATALOGS: Record<string, Catalog> = {
   zh_TW: zhTWMessages as unknown as Catalog,
 };
 
-/** Locale preference: "auto" follows the browser, or a concrete catalog id. */
-export type LocalePref = "auto" | "en" | "zh_CN" | "zh_TW";
+/** A concrete catalog id. English is the default; other locales are opt-in. */
+export type LocalePref = "en" | "zh_CN" | "zh_TW";
 /** Order shown in the language picker. */
-export const LOCALE_OPTIONS: LocalePref[] = ["auto", "en", "zh_CN", "zh_TW"];
+export const LOCALE_OPTIONS: LocalePref[] = ["en", "zh_CN", "zh_TW"];
 /** chrome.storage.local key holding the LocalePref. */
 export const LOCALE_KEY = "locale";
+/** Locale used when the user hasn't explicitly picked one. */
+export const DEFAULT_LOCALE: LocalePref = "en";
 
-/** Map the browser UI language to one of our catalogs (en fallback). */
-function resolveAuto(): string {
-  let ui = "en";
-  try {
-    const g = globalThis as unknown as { chrome?: { i18n?: { getUILanguage?: () => string } } };
-    ui = g.chrome?.i18n?.getUILanguage?.() || "en";
-  } catch {
-    ui = "en";
-  }
-  const lc = ui.toLowerCase();
-  if (lc.startsWith("zh")) {
-    // Traditional for Taiwan / Hong Kong / Macau / explicit Hant script.
-    return /hant|-tw|-hk|-mo/.test(lc) ? "zh_TW" : "zh_CN";
-  }
-  return "en";
+/** Normalize an arbitrary stored value to a known locale (en fallback). Also
+ * absorbs the legacy "auto" preference, which no longer exists. */
+function normalize(pref: unknown): LocalePref {
+  return typeof pref === "string" && pref in CATALOGS ? (pref as LocalePref) : DEFAULT_LOCALE;
 }
 
-let currentLocale = resolveAuto();
+let currentLocale: LocalePref = DEFAULT_LOCALE;
 
 /** Apply a preference immediately (synchronous). */
 export function setLocale(pref: LocalePref): void {
-  currentLocale = pref === "auto" ? resolveAuto() : pref;
+  currentLocale = normalize(pref);
 }
 
 /**
- * Load the stored preference and apply it. Resolves to the stored pref
- * ("auto" when unset or storage is unavailable) so callers can reflect it in a
- * picker. Safe to call repeatedly.
+ * Load the stored preference and apply it. Resolves to the effective locale
+ * (DEFAULT_LOCALE when unset, unrecognized, or storage is unavailable) so
+ * callers can reflect it in a picker. Safe to call repeatedly.
  */
 export function initLocale(): Promise<LocalePref> {
   return new Promise((resolve) => {
     try {
       chrome.storage.local.get([LOCALE_KEY], (result) => {
-        const pref = (result?.[LOCALE_KEY] as LocalePref) || "auto";
+        const pref = normalize(result?.[LOCALE_KEY]);
         setLocale(pref);
         resolve(pref);
       });
     } catch {
-      resolve("auto");
+      resolve(DEFAULT_LOCALE);
     }
   });
 }
diff --git a/static/options.html b/static/options.html
index a2371e0..6759d2b 100644
--- a/static/options.html
+++ b/static/options.html
@@ -460,7 +460,6 @@ <h2 class="brand-title" data-i18n="settingsTitle">Settings</h2>
     <div class="lang-row">
       <span class="lang-label" data-i18n="language">Language</span>
       <select id="langSelect" class="lang-select">
-        <option value="auto" data-i18n="langFollowBrowser">Follow browser</option>
         <option value="en">English</option>
         <option value="zh_CN">简体中文</option>
         <option value="zh_TW">繁體中文</option>