Codex IDE extension fails to open in Cursor due to Secondary Side Bar restriction

What version of the IDE extension are you using?

26.818.21641

What subscription do you have?

ChatGPT Plus

Which IDE are you using?

Cursor

What platform is your computer?

Darwin 23.6.0 arm64 arm

What issue are you seeing?

The Codex IDE extension activates successfully in Cursor, but the Codex sidebar does not open.

When I run the command “Codex: Open Codex Sidebar” from the Command Palette, there is no visible response. The Codex sidebar and sign-in interface do not appear.

In “Developer: Show Running Extensions”, the Codex extension is shown as activated, but the following warning appears:

“View containers cannot be contributed to the Secondary Side Bar in Cursor. It is reserved for Cursor's agent UI. Contribute to 'activitybar' or 'panel' instead.”

Expected behavior:
The Codex sidebar should open and display the ChatGPT sign-in interface.

Actual behavior:
The extension activates, but its user interface cannot be opened because the Secondary Side Bar contribution is rejected by Cursor.

<img width="1446" height="72" alt="Image" src="https://github.com/user-attachments/assets/ea06289c-843c-4598-aec4-4718d42e1d48" />

What steps can reproduce the bug?

1. Open Cursor on macOS.
2. Install and enable the official “Codex – OpenAI’s coding agent” extension.
3. Restart Cursor or run “Developer: Reload Window”.
4. Open the Command Palette.
5. Run “Codex: Open Codex Sidebar”.
6. Observe that no Codex sidebar or sign-in interface appears.
7. Run “Developer: Show Running Extensions”.
8. Observe that the Codex extension is activated, but it displays the following warning:

“View containers cannot be contributed to the Secondary Side Bar in Cursor. It is reserved for Cursor's agent UI. Contribute to 'activitybar' or 'panel' instead.”

I also tried restarting the extension host, reloading Cursor, resetting view locations, and testing both the release and pre-release versions, but the problem persisted.

What is the expected behavior?

Running “Codex: Open Codex Sidebar” should open the Codex interface in Cursor. If the user is not authenticated, the extension should display the ChatGPT sign-in interface. After authentication, the user should be able to access Codex and start a new conversation from the sidebar.

Additional information

The extension itself appears under “Developer: Show Running Extensions” and is successfully activated. However, Cursor rejects the extension’s Secondary Side Bar view contribution.

I have already tried the following troubleshooting steps:

Restarting the extension
Reloading the Cursor window
Restarting Cursor
Resetting view locations
Testing both the release and pre-release versions of the Codex extension

The issue persisted after all of these steps. A screenshot of the warning message is attached.