Instructions are not valid

What version of Codex is running?

codex-cli 0.31.0

Which model were you using?

gpt-5

What platform is your computer?

Darwin 24.5.0 arm64 arm

What steps can reproduce the bug?

This will be triggered when experimental_instructions_file is configured in config.toml and the prompt in that file differs from the built-in prompt in codex-core.

What is the expected behavior?

run normally

What do you see instead?

⚠️ stream error: unexpected status 400 Bad Request: {"detail":"Instructions are not valid"}; retrying 1/5 in 203ms…

⚠️ stream error: unexpected status 400 Bad Request: {"detail":"Instructions are not valid"}; retrying 2/5 in 376ms…

⚠️ stream error: unexpected status 400 Bad Request: {"detail":"Instructions are not valid"}; retrying 3/5 in 787ms…

⚠️ stream error: unexpected status 400 Bad Request: {"detail":"Instructions are not valid"}; retrying 4/5 in 1.443s…

⚠️ stream error: unexpected status 400 Bad Request: {"detail":"Instructions are not valid"}; retrying 5/5 in 2.966s…

🖐  unexpected status 400 Bad Request: {"detail":"Instructions are not valid"}

Additional information

_No response_