Project-attached new threads start on GPT-5.4 instead of configured GPT-5.5

Summary

In Codex Desktop, when I start a new thread from a project-attached environment, the thread starts on gpt-5.4 even though my default model is configured as gpt-5.5.

I can change the model to gpt-5.5 after opening the thread, but that is not the issue.
The problem is that the thread does not start on gpt-5.5 from the beginning.

This issue appears to be project-specific. Other projects on the same machine start new threads with the configured default model correctly, but this particular attached project environment consistently starts new threads on gpt-5.4.

Expected behavior

A new thread created from the project screen / attached project environment should start with the configured default model: gpt-5.5.

Actual behavior

A new thread created from this specific project-attached environment starts on gpt-5.4.
Inside the thread, I can manually switch to gpt-5.5, but the initial thread model is still gpt-5.4.

This does not happen with other projects on the same machine. So far, I have only been able to reproduce it with this particular attached project environment.

Repro steps

1. Set default model to gpt-5.5 in ~/.codex/config.toml
2. Open Codex Desktop
3. Attach or reconnect the affected local project environment
4. Start a new thread from that project
5. Observe that the thread starts on gpt-5.4 instead of gpt-5.5

What I already checked

• config.toml default model is gpt-5.5
• gpt-5.5 is available and selectable inside an opened thread
• Deleting .codex-global-state.json and reconnecting the project does not fix it
• This happens at thread creation time, not only in UI display
• Other projects on the same machine start new threads with the configured default model correctly
• The issue only occurs for this particular attached project environment

Local evidence

On my machine, newly created project threads for this affected project are written with gpt-5.4 in the local thread DB even though the configured default is gpt-5.5.

Example:

• Default config: C:\Users\dlffo\.codex\config.toml
• New affected thread created on May 7, 2026 at about 11:17 AM starts as gpt-5.4
• Switching to gpt-5.5 is possible only after entering the thread

Environment

• Codex Desktop CLI/session version seen in local session metadata: 0.128.0-alpha.1
• Local version file currently shows:
• latest_version: 0.118.0
• OS: Windows

Notes

This appears to be a bug in the project attach / new-thread bootstrap path, where the initial thread model ignores the configured default model and falls back to gpt-5.4.

Since other projects on the same machine do not reproduce the issue, it may be related to this specific project's attached-environment state, cached metadata, or project-level thread bootstrap data.