macOS: Cloudflare 403 blocks all chatgpt.com/backend-api/codex/responses requests — CLI unusable while browser works on same network

What version of Codex CLI is running?

0.121.0

What subscription do you have?

ChatGPT Pro (Personal org, active subscription)

Which model were you using?

gpt-5.4

What platform is your computer?

Darwin 25.2.0 x86_64 i386

What terminal emulator and version are you using (if applicable)?

macOS Terminal.app (default), no multiplexer

What issue are you seeing?

Codex CLI fails with 403 Forbidden on every request to
https://chatgpt.com/backend-api/codex/responses

What steps can reproduce the bug?

1. codex login (OAuth via ChatGPT, completes successfully)
2. codex login status → "Logged in using ChatGPT"
3. Run codex and send any prompt (e.g. "explain this codebase")
4. Response: 403 Forbidden from chatgpt.com (cf-ray above)

Reproduces 100% of the time on 0.121.0.

Same network, same account, same machine — browser access
to chatgpt.com/codex works fine.

What is the expected behavior?

CLI should reach the backend and return a normal response,
the same way the browser client does on the same account/network.

Additional information

Likely the same root cause as #17860 (rustls TLS fingerprint
detected as non-browser traffic by Cloudflare).