VS Code extension should support custom chat font family or honor VS Code chat.fontFamily

What variant of Codex are you using?

IDE Extension

What feature would you like to see?

The Codex VS Code extension currently appears to use its own webview font stack and does not honor VS Code settings such as:

• chat.fontFamily
• chat.editor.fontFamily
• editor.fontFamily

This is especially problematic on Japanese Windows systems when writing Chinese/Japanese mixed text. Because the system font fallback prefers Japanese CJK glyphs, Chinese text is rendered with Japanese-style glyph forms, making long Chinese conversations harder to read.

The standalone Codex app already allows font customization, which solves this issue. It would be very helpful if the VS Code extension could either:

1. Honor VS Code's existing chat.fontFamily / chat.editor.fontFamily settings, or
2. Add a Codex-specific setting, for example:

• chatgpt.fontFamily
• chatgpt.fontSize
• chatgpt.fontLigatures

Expected behavior:
The Codex chat webview should allow users to choose a CJK-friendly font such as:

• Sarasa UI CL
• Sarasa Mono CL
• Microsoft YaHei UI
• Noto Sans CJK SC
• Source Han Sans CN

Why this matters:
For users working in multilingual environments, especially Chinese + Japanese + English, font fallback is not cosmetic. It directly affects readability and fatigue during long coding-agent conversations.
<img width="870" height="98" alt="Image" src="https://github.com/user-attachments/assets/eb21e0d2-bdc0-44d1-99bb-219ff9be858e" />

Environment:

• OS: Windows, Japanese system locale / Japanese UI environment
• VS Code extension: openai.chatgpt
• VS Code settings already configured:
• chat.fontFamily
• chat.editor.fontFamily
• editor.fontFamily
• These settings do not appear to affect the Codex extension webview.

Additional information

_No response_