Regression in codex-cli 0.143.0: Existing conversation fails with Unknown parameter: input[...].namespace, but works in 0.142.0

What version of the Codex App are you using (From “About Codex” dialog)?

Codex CLI: 0.143.0

What subscription do you have?

plus

What platform is your computer?

6.18.33.2-microsoft-standard-WSL2 #1 SMP PREEMPT_DYNAMIC Thu Jun 18 21:54:43 UTC 2026 x86_64 x86_64 x86_64 GNU/Linuxx

What issue are you seeing?

After upgrading from codex-cli 0.142.0 to 0.143.0, one of my existing conversations can no longer continue.

Every new prompt in that conversation fails with the following error:

{
"type": "error",
"error": {
"type": "invalid_request_error",
"message": "[ObjectParam] [input[591].namespace] [unknown_parameter] Unknown parameter: 'input[591].namespace'."
},
"status": 400
}
If I downgrade back to codex-cli 0.142.0, the exact same conversation works normally again without any other changes.

This appears to be a regression introduced in 0.143.0, possibly related to how existing conversation history is serialized or sent to the Responses API.

What steps can reproduce the bug?

Start with an existing conversation created before upgrading.
Upgrade Codex CLI from 0.142.0 to 0.143.0.
Continue the existing conversation.
Observe the Unknown parameter: input[591].namespace error.
Downgrade back to 0.142.0.
Continue the same conversation again.
The conversation works normally.

What is the expected behavior?

Existing conversations should continue to work after upgrading the CLI.

Additional information

New conversations may work normally.
The issue only affects at least one existing conversation.
The same conversation succeeds immediately after downgrading to 0.142.0, which suggests the problem is version-specific rather than caused by the conversation content itself.