[Windows ARM64] Codex Desktop cannot install Primary Runtime because runtime manifest has no windows-arm64 target

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

26.818.5229.0 (Microsoft Store, ARM64)

What subscription do you have?

ChatGPT Plus

What platform is your computer?

Windows 11 ARM64

What issue are you seeing?

Codex Desktop is usable on Windows 11 ARM64, but Codex dependencies / Primary Runtime cannot be installed.

In Settings, the app shows:

• Current version: Not installed
• Unable to reinstall Codex dependencies

The desktop log shows that Codex selects:

target=win32-arm64

However, the Primary Runtime configuration only contains a Windows x64 package:

windows-x86_64

There is no windows-arm64 or windows-aarch64 entry.

When I click "Reinstall", installation fails before the runtime archive is downloaded or extracted:

primary_runtime_install_started
forceReinstall=true
release=latest
target=win32-arm64
trigger=repair

Then:

primary_runtime_bundle_install_outcome
bundleVersion=null
errorMessage="Failed to download primary runtime manifest (404 )."
failureStage=resolve_manifest
outcome=failed
retryable=false
target=win32-arm64

And:

primary_runtime_install_failed
failureDomain=bundle
failureStage=resolve_manifest
errorMessage="Failed to download primary runtime manifest (404 )."
target=win32-arm64

The runtime configuration logged immediately before the failure includes:

bundleVersion=26.819.11345
windows-x86_64 -> codex-primary-runtime-win32-x64-26.819.11345.tar.gz

but no Windows ARM64 Primary Runtime.

This appears to be a platform/runtime-manifest issue rather than a local Node or npm failure.

What steps can reproduce the bug?

1. Use a Windows 11 ARM64 machine.

1. Install Codex Desktop from the Microsoft Store.

1. Confirm that the installed Codex package is ARM64.

My installed package is:

Name: OpenAI.Codex
Version: 26.818.5229.0
Architecture: Arm64

1. Open Codex Desktop.

1. Go to:

Settings -> Configuration -> Workspace dependencies -> Codex dependencies

1. The UI shows:

Current version: Not installed

1. Click "Reinstall".

1. Codex reports:

Unable to reinstall Codex dependencies

1. Check the Codex Desktop log.

The repair attempt contains:

target=win32-arm64
failureStage=resolve_manifest
errorMessage="Failed to download primary runtime manifest (404 )."
retryable=false

This issue occurs in the Desktop runtime installer and is not associated with a model conversation, so session ID, token usage and context window usage are not applicable.

What is the expected behavior?

Codex Desktop on Windows ARM64 should be able to install its Primary Runtime successfully.

Ideally, the Primary Runtime manifest should provide a native Windows ARM64 artifact, such as:

windows-arm64

If a native ARM64 Primary Runtime is not currently available, Codex Desktop could optionally support the existing Windows x64 Primary Runtime through Windows 11 ARM64 x64 emulation / Prism, if that configuration is compatible.

After successful installation, the Settings page should display an installed runtime version instead of:

Current version: Not installed

Additional information

I performed several checks to rule out common local environment problems.

Codex already installs another bundled runtime successfully as native ARM64.

Its manifest reports:

platform: windows
arch: arm64
target: windows-arm64
node_version: 24.19.0

The bundled Node executable runs successfully:

arm64 v24.19.0

The bundled runtime validation script also completes successfully:

validated node_path=...
node_repl_path=...
node_modules=...

Other checks already completed:

• Windows Long Paths are enabled: LongPathsEnabled = 1
• System Node is native ARM64 and functional
• npm.cmd works
• Codex can execute commands normally
• Codex can read and write files in the workspace
• Reinstalling Codex Desktop from the Microsoft Store did not resolve the issue
• PowerShell Execution Policy was tested and was not the cause
• The failure occurs at resolve_manifest, before runtime archive download or extraction

The runtime configuration currently contains Windows artifacts only for:

windows-x86_64

while the native ARM64 Codex Desktop requests:

win32-arm64

This mismatch appears to be the direct cause of the installation failure.