Initial new-chat conversation ignores selected model and falls back to GPT-5.5

Summary

In a brand-new chat, the first conversation appears to ignore the selected model and defaults to GPT-5.5 (medium intelligence), even when the user tries to switch before sending the first message.

Observed behavior

• This only happens in the initial / first conversation state of a new chat.
• After the first message is sent, the model selector appears to behave normally.
• The UI may show a different selection, but the first turn still executes with GPT-5.5.

Expected behavior

The model selected by the user before the first message should be the model used for that first turn.

Reproduction steps

1. Open a new chat.
2. Before sending the first message, open the model selector.
3. Choose a model other than GPT-5.5.
4. Send the first message.
5. Observe that the first turn still uses GPT-5.5 / medium intelligence.
6. Send a follow-up message and observe that the selector then appears to work normally.

Environment

• Variant: Codex App (desktop app)
• Platform: Windows

Notes

This looks like a startup / initialization precedence issue in the first conversation state rather than a general selector bug.