Conversation recap language is incorrectly inferred from timezone

What version of the Codex App are you using?

Codex App for Windows 26.825.6671.0

What subscription do you have?

Unknown (not exposed to the reporting agent)

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

An automatic Conversation recap was generated in German even though the entire conversation and the system UI locale were English.

Actual recap (Windows username redacted):

Die alte Konfiguration C:\Users<REDACTED>.spinloaf wurde in den Papierkorb verschoben und eine neue Entwicklungssitzung gestartet. pnpm run dev läuft erfolgreich unter http://127.0.0.1:3084; die Aufgabe ist abgeschlossen.

The user does not understand German.

What steps can reproduce the bug?

1. Use Codex App on Windows with an English conversation.
2. Have Windows configured with the W. Europe Standard Time timezone. Node exposes this as the IANA identifier Europe/Berlin.
3. Continue a sufficiently long/tool-heavy thread until Codex creates a visible Conversation recap.
4. Observe that the recap is written in German instead of English.

Verified environment signals:

• Conversation language: English
• Windows culture: en-US
• Windows UI culture: en-US
• Installed UI culture: en-US
• LANG: C.UTF-8
• LC_ALL: C.UTF-8
• Windows timezone: W. Europe Standard Time
• Node timezone: Europe/Berlin
• TZ environment variable: unset
• No language or locale entry in Codex settings

What is the expected behavior?

Conversation recaps should preserve the conversation language or follow an explicit UI/language preference. A timezone identifier must not be treated as a language or country preference. Europe/Berlin is a technical timezone identifier used across multiple countries and does not imply that the user understands German.

Additional information

The assistant's normal responses before and after compaction remained in English. Only the automatically generated Conversation recap switched to German, suggesting the recap-generation path applies a different language-selection heuristic.

Start by tracing the Conversation recap generation path and its language-selection heuristic, using the reported Windows and Node timezone signals as the reproduction setup. Verify that an English conversation with Europe/Berlin still produces an English recap, and add or update coverage for the timezone-versus-language case.