Windows: Codex 0.123.0 injects both PATH and Path into the shell environment, breaking PowerShell Env provider and causing intermittent shell startup failures

What version of Codex CLI is running?

codex-cli 0.123.0

What subscription do you have?

ChatGPT Pro

Which model were you using?

gpt-5.4

What platform is your computer?

Microsoft Windows x64

What terminal emulator and version are you using (if applicable)?

Codex Desktop app on Windows, with the npm-installed codex also on PATH

What issue are you seeing?

On Windows, Codex appears to construct a malformed process environment for shell execution by injecting both PATH and Path into the same process environment block.

Because Windows environment variables are case-insensitive, PowerShell's Env: provider treats this as a duplicate-key collision and fails with:

Get-ChildItem : An item with the same key has already been added.

In earlier threads on the same machine, this also correlated with Codex shell startup failures before command execution, including:

Internal Windows PowerShell error. Loading managed Windows PowerShell failed with error 8009001d.

So the root problem here appears to be malformed Windows env var merging in Codex, not a repo-specific issue.

What steps can reproduce the bug?

In a Codex Windows session:

1. Confirm the installed CLI version:

``powershell
codex --version
`
Observed:
`text
codex-cli 0.123.0
``

1. Confirm the npm package version:

``powershell
npm list -g @openai/codex --depth=0
`
Observed:
`text
@openai/codex@0.123.0
``

1. Inspect the effective process environment from within the Codex shell context:

``powershell
cmd /c "set PATH & set Path"
`
Observed: both PATH= and Path=` are present in the same process environment.

1. Try enumerating the PowerShell env provider:

``powershell
Get-ChildItem Env:
`
Observed:
`text
Get-ChildItem : An item with the same key has already been added.
``

1. Compare against the actual Windows environment sources:

``powershell
reg query "HKCU\Environment"
reg query "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment"
`
Observed: only Path exists in the registry sources, not a separate uppercase PATH`.

What is the expected behavior?

Codex should normalize Windows environment variables case-insensitively before spawning the shell.

Expected behavior:

• only one canonical Path entry should be present in the spawned process environment
• Get-ChildItem Env: should succeed normally
• shell startup should not intermittently fail due to malformed env state

What do you see instead?

Codex spawns a shell environment that includes both PATH and Path, which breaks PowerShell env enumeration and appears to contribute to intermittent shell startup failures.

Additional information

Concrete local evidence:

• where codex resolves the npm global install first:
• C:\Users\hnili\AppData\Roaming\npm\codex
• In the Codex shell process, both PATH and Path are present.
• In HKCU\Environment and HKLM\...\Environment, only Path exists.
• So the duplicate is being introduced during Codex environment construction, not inherited directly from Windows registry state.

This looks distinct from the broader 8009001d symptom reports because it provides a narrower repro and a likely root cause.

Possibly related:

• #19100
• #13917
• #14057
• #18465