openai / openai/codex

model choosing error

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#40,092 2 comments 0 reactions 0 assignees View on GitHub

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app bug model-behavior
Dominant language
Rust
Stars
125k
Forks
19.5k
PR merge metrics
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Description

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

26.818.41509

What subscription do you have?

ChatGPT Plus

What platform is your computer?

Darwin 25.4.0 arm64 arm

What issue are you seeing?

I selected GPT-5.6 in the Codex App, but when I asked the assistant which model it was using, it repeatedly reported a different model (GPT-5.5-mini).

During the same conversation, the assistant gave multiple inconsistent answers about its model identity, including GPT-5.5-mini, GPT-5.5 Thinking, and GPT-5.6 Sol.

The model selected in the UI was GPT-5.6, so I am unable to determine whether:

  1. the app routed the conversation to the wrong backend model, or
  2. the correct model was used but the assistant received or reported incorrect model identity information.

Expected behavior:
When GPT-5.6 is explicitly selected in the model selector, the request should be routed to GPT-5.6, and the assistant's reported model identity should be consistent with the selected/routed model.

Please investigate whether there is a mismatch between the Codex App model selector, backend model routing, and the model identity information exposed to the assistant.

What steps can reproduce the bug?

Feedback ID: no-active-thread-01a02901-da06-7a23-85af-e7439db1db3e

What is the expected behavior?

Please give me feedback and tell me why the condition is happening..

Additional information

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

No source file or test is named. Start by tracing the Codex App model selector and the backend routing or model-identity path, using feedback ID no-active-thread-01a02901-da06-7a23-85af-e7439db1db3e. Determine whether GPT-5.6 was routed correctly or whether the identity exposed to the assistant is wrong, and verify that the selected and reported models are consistent.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
ai, backend-api-design
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Active
Clarity
Needs clarification
Newbie friendliness
35/100

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