Codex skips modifying important files because it incorrectly assumes they are handled by subagents

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

26.513.40821

What subscription do you have?

Plus

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

In some Codex sessions, important files are not modified even though they are directly related to the requested task and subagents are not being used.

Based on the session output, Codex appears to identify these files as "dirty" during its Git diff scanning process, but then avoids modifying them because it incorrectly assumes they are being managed by a subagent. As a result, Codex may acknowledge that a file requires changes while refusing to update it.

No explicit error message is shown. Instead, the issue manifests as Codex repeatedly mentioning the file or its modified state without making the necessary edits.

What steps can reproduce the bug?

1. Start a Codex session on a repository that contains modified ("dirty") files.
2. Ensure subagents are not enabled or used.
3. Ask Codex to make changes that require modifications to one or more of the dirty files.
4. Observe that Codex recognizes the files and may mention them during planning or analysis.
5. Codex avoids editing the files despite them being necessary to complete the task.

What is the expected behavior?

Codex should modify the relevant files required to complete the requested task when subagents are not enabled.

The presence of dirty files should not cause Codex to incorrectly assume that a subagent owns those files. If Codex intentionally skips a file, it should provide a clear and descriptive explanation for why the file cannot be modified.

Additional information

This behavior appears to be related to Codex's Git diff scanning strategy. It may be incorrectly classifying dirty files as belonging to a subagent workflow even when no subagent is active.

The issue can prevent task completion because the files that require modification are often the same files Codex refuses to edit.