diff --git a/docs/ROADMAP.md b/docs/ROADMAP.md
index 748b825..ec55cda 100644
--- a/docs/ROADMAP.md
+++ b/docs/ROADMAP.md
@@ -164,6 +164,10 @@
 - [x] ~~首启动空屏~~（v0.2.1：启动自动打开一个终端）
 - [ ] zh-TW 用语统一（i18n 质量专项）：`命令/指令` 全文件混用（panels/ssh/settings/terminal，台湾惯用「指令」）、`口令`→`密碼`（ssh.secret.passphrase）、顺带通读 服务器→伺服器 / 默认→預設 / 网络→網路 / 软件→軟體。需要一次全局连贯的专项，零散改会制造新的不一致
 - [ ] ja 片假名长音符号统一：`フォルダ`(6) / `フォルダー`(7) 混用，二选一全局统一
+- [ ] 周期检查可被高频设置写入推迟（updater：每次 mutateSettings 重排 4h 定时器，字体快捷键连按/ColorPicker 拖动会重置倒计时；改为「仅 interval 值变化时重排」或记录上次触发时间）
+- [ ] 「启动时自动检查」运行中途拨开会在 ~5s 后立即检查（startupArmed 语义应为下次启动生效）
+- [ ] 下载无整体超时：检查有 withTimeout，下载没有——慢滴流可让 downloading 卡死且自动下载不再重试（需设计，不能简单套超时杀死慢速下载）
+- [ ] release.cjs `--channel-only` 与 `--skip-gitea` 组合矛盾（channel-only 先 return，警告永不打印，Gitea 通道仍会上传）
 - [ ] autoWrap=false 的固定列宽模式（xterm.js 无原生 wrapMode，需自定义列数控制）
 - [ ] 终端标题跟随 OSC 序列（窗格标题显示当前目录/命令）
 - [ ] 内置等宽字体打包（OFL 许可：JetBrains Mono / Fira Code 等）
diff --git a/src/main/updater.ts b/src/main/updater.ts
index 7802a3a..b2ce8d0 100644
--- a/src/main/updater.ts
+++ b/src/main/updater.ts
@@ -323,11 +323,17 @@ async function performCheck(source: CheckSource): Promise<UpdateState> {
  */
 export function runCheck(source: CheckSource = 'manual'): Promise<UpdateState> {
   // A manual check is an explicit act, so whatever it finds counts as news even
-  // if this run has already dealt with that version: the suppression record is
-  // dropped here — before the in-flight guard, so a click that joins a check
-  // already running gets the same treatment. (A manual DOWNLOAD needs no
-  // equivalent: its entry point never consults the record.)
-  if (source === 'manual') actedRelease = undefined
+  // if this run has already announced that version: the announcement half of the
+  // record is dropped here — before the in-flight guard, so a click that joins a
+  // check already running gets the same treatment. The DOWNLOADED half is kept:
+  // for a release whose package sits on disk, "downloaded" *is* the truthful
+  // answer, and dropping it made update-available report `available` again —
+  // folding the About tab's install button back into "download" for a manual
+  // check on an already-fetched release. (A manual DOWNLOAD needs no equivalent:
+  // its entry point never consults the record.)
+  if (source === 'manual') {
+    actedRelease = actedRelease?.downloaded ? actedRelease : undefined
+  }
   if (checkInFlight) return checkInFlight
   const task = performCheck(source)
   checkInFlight = task
diff --git a/src/renderer/src/workspace/ZmodemOffers.tsx b/src/renderer/src/workspace/ZmodemOffers.tsx
index 8f31b7e..5436269 100644
--- a/src/renderer/src/workspace/ZmodemOffers.tsx
+++ b/src/renderer/src/workspace/ZmodemOffers.tsx
@@ -1,7 +1,8 @@
 import { useCallback, useEffect, useRef, useState } from 'react'
 import { App as AntdApp, Button, Modal, Space, Typography } from 'antd'
 import type { ZmodemOfferEvent, ZmodemResponse } from '@shared/ipc'
-import { t } from '@shared/i18n'
+import { DEFAULT_LANGUAGE, t, tFor } from '@shared/i18n'
+import { useSettingsStore } from '../settings/store'
 
 /**
  * M6 ZMODEM offer/done UX: renders one dialog per active zmodem offer.
@@ -15,6 +16,10 @@ import { t } from '@shared/i18n'
  */
 export default function ZmodemOffers(): null | React.JSX.Element {
   const { message } = AntdApp.useApp()
+  // Rendered as App's sibling: a language switch re-renders App, but the parent's
+  // children element is identical, so this subtree bails out and would keep the
+  // old language. Subscribe here and translate with the explicit language.
+  const language = useSettingsStore((s) => s.settings.system.language ?? DEFAULT_LANGUAGE)
   const [offers, setOffers] = useState<Map<string, ZmodemOfferEvent>>(new Map())
   const busyRef = useRef<Set<string>>(new Set())
 
@@ -117,21 +122,21 @@ export default function ZmodemOffers(): null | React.JSX.Element {
       closable={false}
       maskClosable={false}
       keyboard={false}
-      title={isReceive ? t('ssh.zmodem.titleReceive') : t('ssh.zmodem.titleSend')}
+      title={isReceive ? tFor(language, 'ssh.zmodem.titleReceive') : tFor(language, 'ssh.zmodem.titleSend')}
       footer={
         <Space>
           <Button
             type="primary"
             onClick={() => (isReceive ? void handlePickDir(first.id) : void handlePickFiles(first.id))}
           >
-            {isReceive ? t('ssh.zmodem.pickDir') : t('ssh.zmodem.pickFiles')}
+            {isReceive ? tFor(language, 'ssh.zmodem.pickDir') : tFor(language, 'ssh.zmodem.pickFiles')}
           </Button>
-          <Button onClick={() => handleCancel(first.id)}>{t('common.cancel')}</Button>
+          <Button onClick={() => handleCancel(first.id)}>{tFor(language, 'common.cancel')}</Button>
         </Space>
       }
     >
       <Typography.Text>
-        {isReceive ? t('ssh.zmodem.receiveDesc') : t('ssh.zmodem.sendDesc')}
+        {isReceive ? tFor(language, 'ssh.zmodem.receiveDesc') : tFor(language, 'ssh.zmodem.sendDesc')}
       </Typography.Text>
     </Modal>
   )
diff --git a/tests/updater-fallback.mjs b/tests/updater-fallback.mjs
index c56a2ed..56259d8 100644
--- a/tests/updater-fallback.mjs
+++ b/tests/updater-fallback.mjs
@@ -986,6 +986,28 @@ console.log('a finished download stays finished')
     ok(s.status === 'available', `a different release starts from 'available' (got '${s.status}')`)
     ok(s.version === '4.4.2', `and is named (${s.version})`)
   }
+
+  // A manual check after a finished download must ALSO keep the downloaded
+  // state — the package is on disk, so "downloaded" is the truthful answer, and
+  // folding the install button back into "download" would make the user fetch
+  // what they already have. The manual record drop only discards announcement
+  // bookkeeping, never the on-disk fact.
+  live.emit('update-downloaded', { version: '4.4.2' })
+  await tick()
+  ok(call(Ipc.UPDATE_STATE_GET).status === 'downloaded', 'the new release finishes too')
+  ctl.checkForUpdates = () => {
+    live.emit('checking-for-update')
+    live.emit('update-available', { version: '4.4.2' })
+    return Promise.resolve(null)
+  }
+  {
+    const state = await call(Ipc.UPDATE_CHECK)
+    ok(
+      state.status === 'downloaded' && state.version === '4.4.2',
+      `a manual check keeps a finished download finished (got '${state.status}')`
+    )
+    ok(state.status !== 'checking', 'and is not parked on the spinner')
+  }
 }
 
 console.log('balloons respect the visible-window guard')
diff --git a/website/assets/i18n-apply.js b/website/assets/i18n-apply.js
index baff421..910cb1c 100644
--- a/website/assets/i18n-apply.js
+++ b/website/assets/i18n-apply.js
@@ -27,6 +27,8 @@
     if (!tag) return null;
     var t = String(tag).replace(/_/g, '-');
     if (/^zh-?(tw|hk|mo)/i.test(t)) return 'zh-TW';
+    // zh-Hant-* is Traditional by definition (kept in sync with the head script).
+    if (/^zh-hant/i.test(t)) return 'zh-TW';
     if (/^zh/i.test(t)) return 'zh-CN';
     if (/^ja/i.test(t)) return 'ja';
     if (/^en/i.test(t)) return 'en';
diff --git a/website/index.html b/website/index.html
index 9dc1f1e..bb467f0 100644
--- a/website/index.html
+++ b/website/index.html
@@ -27,6 +27,9 @@
         if (!tag) return null;
         var t = String(tag).replace(/_/g, '-');
         if (/^zh-?(tw|hk|mo)/i.test(t)) return 'zh-TW';
+        // BCP-47 can carry a script subtag (zh-Hant-TW, zh-Hant-HK, zh-Hant):
+        // some browsers report those forms, and they are Traditional by definition.
+        if (/^zh-hant/i.test(t)) return 'zh-TW';
         if (/^zh/i.test(t)) return 'zh-CN';
         if (/^ja/i.test(t)) return 'ja';
         if (/^en/i.test(t)) return 'en';
@@ -35,7 +38,12 @@
       function pickLang() {
         var m = /[?&]lang=([^&]+)/.exec(location.search);
         if (m) {
-          var fromUrl = normalize(decodeURIComponent(m[1]));
+          // A truncated % escape in a shared link must not throw inside this
+          // first-frame IIFE: a throw here would skip setting html[lang] AND the
+          // pending flag, leaving the page stuck on the default language.
+          var raw = null;
+          try { raw = decodeURIComponent(m[1]); } catch (e) {}
+          var fromUrl = normalize(raw);
           if (fromUrl) return fromUrl;
         }
         try {