[Critical][Windows App 26.825] One writable-root setup failure disables exec and apply_patch globally

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

Codex App 26.825.4187.0; bundled Codex CLI 0.149.0.

What subscription do you have?

Not disclosed in this public report.

What platform is your computer?

Windows 11 Pro x64, build 26200. PowerShell 7.6.4.

What issue are you seeing?

Severity: Critical workflow blocker.

The Codex App's Windows workspace-write sandbox repeatedly fails during setup refresh before any requested process starts. If setup cannot update one configured writable root, the entire sandbox becomes unusable, including narrower writable roots that are otherwise valid.

The user-visible error is:

Failed to create unified exec process:
helper_unknown_error: setup refresh had errors

apply_patch fails through the filesystem sandbox helper with the same setup-refresh error before it can read or edit a file.

A sanitized local sandbox log identifies the underlying operation only as:

write ACE grant failed on <WRITABLE_ROOT>: SetNamedSecurityInfoW failed: 5
setup refresh completed with errors
setup error: setup refresh had errors

The following all failed in the same task before process or file access:

• a minimal Get-Location command through bundled PowerShell;
• a read-only Git command through cmd.exe;
• apply_patch on a file inside an explicitly writable task worktree;
• repeated attempts using both native and normalized path syntax.

The same read-only commands succeed when explicitly escalated outside the sandbox. This confirms that the shell, repository, worktree, and requested commands are healthy. There is no equivalent policy-compliant fallback for the required apply_patch editor, so normal repository work cannot be completed.

What steps can reproduce the bug?

1. On Windows, open a local Codex project with multiple configured writable roots, including a broad workspace root and a narrower task worktree.
2. Use workspace-write sandboxing.
3. Run a minimal read-only command such as Get-Location through normal unified exec.
4. Observe that the process never starts and setup refresh returns helper_unknown_error.
5. Retry through cmd.exe; observe the same pre-launch failure.
6. Attempt apply_patch inside the explicitly writable worktree; observe the same sandbox setup failure before file access.
7. Run the read-only command with explicit escalation outside the sandbox; observe that it succeeds.

What is the expected behavior?

• A failure on one redundant or broad writable root must not disable all valid narrower writable roots.
• The helper should skip or isolate the failing root, or provide a supported repair/elevation flow.
• The user-visible error should include the failed operation and Win32 error code instead of only helper_unknown_error.
• apply_patch and read-only exec should remain usable for valid explicitly writable roots.
• Sandbox setup should recover after workspace-root configuration changes without requiring unsafe filesystem workarounds.

Additional information

This is recurring rather than transient and has blocked multiple local tasks. No secrets, repository content, real paths, account identifiers, session identifiers, or customer data are included in this report.

Related open reports reviewed before filing:

• #40596 — same generic unified-exec setup-refresh error
• #40889 — exec_command and apply_patch fail together
• #38290 — pre-launch unified-exec failure
• #36087 — Windows sandbox ACL failures in workspace-write

This report adds a current reproduction on Codex App 26.825.4187.0 and the fail-all behavior where one writable-root setup error disables otherwise valid task-specific roots.

Begin with the Windows workspace-write setup-refresh path and filesystem sandbox helper, reproducing the failure with a minimal PowerShell command and apply_patch against a narrower worktree. Trace the SetNamedSecurityInfoW error and verify that a failing writable root no longer disables valid roots, with clearer error reporting and usable read-only exec.