Desktop app UI switched to English after update - MSIX manifest declares only en-US while zh-CN localization is bundled #52800

What version of the Codex App are you using

26.1002.7124.0 (updated from 26.930.7945.0 on 2026-10-10)

Also staged with the same problem: 26.1007.2314.0

Windows deployment event log confirms the update:

2026-10-10 13:53:39  OpenAI.Codex_26.930.7945.0 is updating to OpenAI.Codex_26.1002.7124.0
2026-10-10 13:54:20  new preferred version: OpenAI.Codex_26.1007.2314.0

What issue are you seeing

After the automatic update the Codex App UI switched from Simplified Chinese to English. The Windows display language is zh-CN and was not changed.

The app still ships full Simplified Chinese localization, but it is never loaded:

• app\locales\zh-CN.pak exists (508.6 KB)
• app.asar -> .vite/build/locales/zh-CN.json contains the translations, e.g. "??", "??", "??"

Root cause appears to be the MSIX manifest, which declares only English:

<Resources>
    <Resource Language="en-US" />
</Resources>

Because of that, Windows reports the app language as en-US, so the app resolves its UI locale to English and skips the bundled Chinese resources.

The i18n bundle also hardcodes the fallback locale: yK = "en-US" and when the resolved locale is en-US an empty message set is used.

Steps to reproduce

1. Use Windows with display language zh-CN (Get-WinUILanguageOverride = zh-Hans-CN)
2. Install / update the Codex App to 26.1002.7124.0
3. Launch the app
4. The whole UI renders in English

Evidence that Windows still reports Chinese to the app:

• The app's own embedded browser profile shows intl.selected_languages = "zh-CN,zh"
• Sentry scope records culture.locale = "zh-CN"

Expected behavior

The UI should be in Simplified Chinese, or at least follow the OS display language, because zh-CN localization is bundled with the app.

Additional information

Verified the installed package contents directly (with admin rights):

• AppxManifest.xml declares only <Resource Language="en-US" /> ? identical in both 26.1002.7124.0 and 26.1007.2314.0
• app\locales\zh-CN.pak is present
• app.asar contains .vite/build/locales/zh-CN.json with the Chinese strings

There is no user-facing language setting anywhere in the app to work around this. Checked:

• ~/.codex/config.toml ? no language / locale key
• ~/.codex/.codex-global-state.json ? no language key
• %APPDATA%\Codex\** (incl. Local Storage / IndexedDB / Preferences) ? no app-level language setting
• The zh-CN translation catalog contains no "language" setting entry

Also tested: launching the already-running instance via IApplicationActivationManager with --lang=zh-CN respawns renderer processes with --lang=zh-CN, but the UI stays English (the main-process locale is fixed at startup).

Request: add the supported languages to the MSIX manifest (e.g. zh-CN, zh-TW, ja-JP ...), or expose a user-facing language setting.

Affected users: every non-English Windows user, with no in-app workaround.