macOS desktop app renders UI text with incorrect font/fallback

Codex macOS desktop app renders UI and code text with incorrect font/fallback

Summary

On macOS 26.4.1, the Codex desktop app renders UI and code text with an abnormal font/fallback. This is visible in both zh-CN and en-US UI. Other apps on the same machine, including VS Code, Terminal, WeChat, and system UI, render text normally.

This appears isolated to the Codex desktop app / Electron renderer font stack rather than a broken system font installation.

Environment

• Codex app: 26.429.61741
• Bundle id: com.openai.codex
• macOS: 26.4.1 (25E253)
• Hardware: MacBook Air, Apple Silicon
• Locale/UI language: zh-CN
• System Chinese font: PingFang SC is installed and visible to CoreText

Visible Symptom

Codex text appears to use an unexpected or degraded font/fallback. The issue is visible even when the Codex UI locale is switched to en-US, so it is not limited to Simplified Chinese text. It is especially noticeable in the new-thread/home UI, permission mode dropdown, and code/terminal-style text.

Other apps on the same machine render comparable English and Chinese text correctly.

Reproduction

1. Install and launch the Codex macOS desktop app.
2. Use the app in zh-CN locale and observe the font rendering.
3. Switch the Codex UI locale to en-US and restart/reopen the app.
4. Open the new-thread/home screen, permission mode dropdown, and code/terminal-style views.
5. Observe that the abnormal font rendering still appears in English UI/code text.
6. Compare with VS Code, Terminal, or native macOS UI on the same machine.

Expected Behavior

Codex should use normal macOS system UI and monospace font resolution, and render both English and Chinese text consistently with other macOS apps.

Actual Behavior

Codex renders UI/code text with an abnormal fallback/appearance. The issue persists after switching the UI locale from zh-CN to en-US. Disabling Codex font smoothing does not fix it.

Diagnostics

CoreText can resolve the expected fonts on this machine:

PingFang SC -> family=PingFang SC, postscript=PingFangSC-Regular
SF Mono -> family=SF Mono, postscript=SFMono-Regular
Menlo -> family=Menlo, postscript=Menlo-Regular

Codex's packaged CSS contains:

--font-sans-default:-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif

There is no explicit CJK fallback such as PingFang SC, Hiragino Sans GB, or Noto Sans CJK SC. However, the issue is not limited to CJK text; it is also visible in en-US UI/code text.

Local workaround:

• Installing Noto Sans CJK SC
• Setting Codex UI font state to Noto Sans CJK SC

This makes the UI more readable, but it is not the expected native macOS app appearance and does not explain why the default English/code font rendering is also abnormal.

Additional Notes

This does not appear to be a global machine/font corruption issue because:

• VS Code renders English and Chinese text normally.
• Terminal renders English and Chinese text normally.
• macOS system UI renders English and Chinese text normally.
• CoreText resolves PingFang SC correctly.

The issue seems specific to Codex desktop app font selection/fallback/rendering on macOS, not a global machine font issue.

<img width="330" height="620" alt="Image" src="https://github.com/user-attachments/assets/fa19b683-90ed-4f8e-a41f-8f609b35d8b2" />
<img width="675" height="370" alt="Image" src="https://github.com/user-attachments/assets/20ea9d5d-5991-47ac-8c93-f02696dc9ea1" />
<img width="1050" height="450" alt="Image" src="https://github.com/user-attachments/assets/aec82252-d504-4c6e-9367-5f27670fd807" />
<img width="575" height="310" alt="Image" src="https://github.com/user-attachments/assets/de2183fb-9b29-4c5e-b55a-b46489827165" />