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codex app does not respect model_reasoning_effort #10643

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Closed as not planned

Description

@SunRunAway

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

260203.1501 (523)

What subscription do you have?

plus

What issue are you seeing?

in .codex/config.toml

model = "gpt-5.2"
model_reasoning_effort = "high"

When I start codex.app, the reasoning level of a new thread is High,
but when click a previous thread, the reasoning level becomes medium.

What steps can reproduce the bug?

  1. Create a new thread in the Codex tui. Right now it uses GPT-5.2 with model_reasoning_effort=high.
  2. Select this session in the Codex app. The UI shows GPT-5.2 medium.

What is the expected behavior?

No response

Additional information

No response

Activity

  1. added
    appIssues related to the Codex desktop app
    on Feb 4, 2026
  2. etraut-openai commented on Feb 4, 2026

    @etraut-openai
    Contributor

    The model_reasoning_effort affects the default reasoning level. When you switch to an existing thread, the app will go back to the reasoning level that was last used in that thread. If you want to change the reasoning level on an existing thread, you can use the control in the UI.

  3. SunRunAway commented on Feb 5, 2026

    @SunRunAway
    Author

    I found a better way to reproduce it.

    1. Create a new thread in the Codex tui. Right now it uses GPT-5.2 with model_reasoning_effort=high.
    2. Select this session in the Codex app. The UI shows GPT-5.2 medium.
  4. SunRunAway commented on Feb 5, 2026

    @SunRunAway
    Author

    And I’ve found that as long as the same thread is used alternately in the Codex TUI and the Codex app, after using the Codex TUI, the thread’s reasoning level in the Codex app gets reset to medium.

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