Adding a parent directory as an additional project source prevents the project from opening

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

26.715.12143

What subscription do you have?

When the parent directory of the current project is added as an additional source, ChatGPT fails to open the project and displays a generic error screen. Restarting the application does not resolve the issue because the invalid source configuration is loaded again on startup.

What platform is your computer?

Microsoft Windows NT 10.0.26100.0 x64

What issue are you seeing?

<img width="1074" height="525" alt="Image" src="https://github.com/user-attachments/assets/dd16d788-0b43-4f8c-a660-a5855b8421ef" />

What steps can reproduce the bug?

Open an existing local project.
Add the project’s parent directory as an additional source.
Close or reopen the project.
The project can no longer be opened, and ChatGPT displays an error.

Example directory structure:

D:\workspace
└── current-project
Main project: D:\workspace\current-project
Additional source: D:\workspace

What is the expected behavior?

The application should either:

support overlapping parent and child source directories safely, or
prevent users from adding a directory that contains the current project.
Actual behavior

The project becomes inaccessible and continues to fail after restarting ChatGPT.

<img width="1074" height="525" alt="Image" src="https://github.com/user-attachments/assets/53ff9193-de58-4643-9209-ba4b6a9fcc52" />

Additional information

_No response_