[Windows Desktop] GPT-5.6 disappeared and all new chats fail with :workspace permission-profile type error

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

OpenAI.Codex_26.820.7780.0_x64

What subscription do you have?

enterprise version

What platform is your computer?

No response

What issue are you seeing?

Codex App version

OpenAI.Codex_26.820.7780.0_x64

Platform

Windows 11 x64

What happened?

GPT-5.6 models were previously available in the Codex Desktop model picker for this same account.

They have now disappeared from the picker, which only shows GPT-5.5 and older models. At the same time, every Codex chat fails:

• resuming existing chats fails
• creating completely new chats also fails

The exact error is:

Invalid request: invalid type: string ":workspace",
expected internally tagged enum PermissionProfileSelectionParams

### Steps to reproduce

1. Open Codex Desktop on Windows.
2. Create a new local chat.
3. Send any prompt.

### Expected behavior

A new chat should start normally, and previously available GPT-5.6 models should remain available in the model picker.

### Actual behavior

The request immediately fails with the permission-profile type error above. GPT-5.6 has also disappeared from the model picker.

### Troubleshooting already attempted

- Updated Codex Desktop to the latest Microsoft Store package available to me.
- Reset the Codex Windows app data using Reset-AppxPackage.
- Confirmed that ~/.codex/config.toml does not contain a custom default_permissions = ":workspace" configuration.
- The issue persists for every new and existing chat.

### Additional context

This looks related to the Desktop model-picker/session/permission-state regressions reported in:

- #31873
- #34137
- #39195

Please investigate whether the Desktop client is sending the built-in :workspace permission profile as a string where the backend now expects PermissionProfileSelectionParams.

### What steps can reproduce the bug?

### Steps to reproduce

1. Open Codex Desktop on Windows.
2. Create a new local chat.
3. Send any prompt.

### What is the expected behavior?

_No response_

### Additional information

_No response_

Start by reproducing the failure in Codex Desktop on Windows 11 with a new local chat, then compare the request behavior with the PermissionProfileSelectionParams error and the related issues #31873, #34137, and #39195. Done means new and existing chats work again and GPT-5.6 is available in the model picker without requiring a custom config.toml setting.