When running models from openrouter providers the model messages are not displayed

What version of Codex is running?

codex-cli 0.16.0

Which model were you using?

openrouter gpt-oss-120b

What platform is your computer?

Darwin 24.5.0 arm64 arm

What steps can reproduce the bug?

Originally seen with the homebrew install of 0.14.0, but re-validated steps today with npm install of 0.16.0.

1. configure oss120 profile using openrouter like below

```[model_providers.openrouter]
name = "OpenRouter"
base_url = "https://openrouter.ai/api/v1"
env_key = "OPENROUTER_API_KEY"

[profiles.oss120]
model_provider = "openrouter"
model = "openai/gpt-oss-120b"

2. set OPENROUTER_API_KEY like usual
3. launch codex with: `codex --profile oss120`
4. prompt something simple 'please summarize the readme'
5. you'll notice commands and plans show as expected, but no 'codex' messages will be added. feels like it just 'gave up' even though the model IS correctly generating the message.

### What is the expected behavior?

'codex' messages should so with messages from the model at the end and during processing.

<img width="1266" height="718" alt="Image" src="https://github.com/user-attachments/assets/8e53b4cd-e31b-4991-af69-4497c35bd1a7" />

### What do you see instead?

<img width="2080" height="1574" alt="Image" src="https://github.com/user-attachments/assets/a229b551-21a7-42d0-92b5-7f869f02fd69" />

### Additional information

will be linking to a fix shortly.