Codex Windows Fast Patch Skill: restoring Codex Desktop features after a Windows upgrade

The problem: a Codex Desktop update on Windows quietly removes local patches

Codex Desktop on Windows ships as a Store / MSIX package. When it updates, the app directory is replaced, and anything that was patched into the packaged files goes with it. The README frames the skill around exactly that failure: after an upgrade, Fast Mode and the gpt-6-astra, gpt-5.6-sol, gpt-5.6-terra and gpt-5.6-luna model entries stop showing, the blue-purple Power drag bar disappears, and the Ultra toggle under a custom provider turns grey. The same update can take out the plugin entry and install buttons, the built-in browser and Chrome / browser_use, Computer Use, the phone remote-control entry, and the Goal entry.

It is also not purely about files being overwritten. The README describes a second class of breakage where a patch survives but stops being effective: Desktop rewrites the surface list in the unified-computer-use plugin cache back to browser, so editing .mcp.json alone does nothing because the value is restored on every Desktop start. There is also a session-visibility case: after switching model_provider or API configuration, old sessions remain on disk but the official sidebar no longer lists them.

The intended user is a Windows Codex Desktop user who already runs local patches and wants them reapplied by an agent rather than by hand. The skill is a set of instructions plus PowerShell reference scripts, not a background service. It is aimed at someone who can point an Agent Skills harness at a directory and let it run PowerShell against an installed MSIX package.

How the patching works: MSIX package, ASAR bundle, hash-gated scripts

The mechanism follows the Windows packaging chain. The scripts use Get-AppxPackage to find the installed package, work on the staged MSIX payload, patch the Electron app.asar inside it, repack, and rewrite the embedded integrity table so the package still launches. The README states that the launcher is identified by content rather than by file name, because builds before 26.9xx use Codex.exe and later ones use ChatGPT.exe. If a binary references app.asar but the integrity table cannot be parsed, the library fails hard rather than installing a package that will not start.

Launching is handled separately. The README warns against running the executable in the install directory directly: on 26.9xx, app\Codex.exe is only a CLI shim and starting it produces no desktop window. The shared launch helper goes through the AppUserModelId instead.

Several patches are deliberately narrow. The Fast Mode patch only unhides model entries that already exist in the current version directory; it does not create entries, so a model that is not present will never appear no matter how many times the patch is reapplied. The Computer Use node_repl fix applies only to exact documented @oai/sky source hashes, and the Win10 screenshot helper fix applies only to the listed helper hashes. The README notes that 0.6.16 and 0.6.17 have identical protected code layout but different whole-file hashes, so a profile must be selected by full hash, not by version prefix. That is a deliberate refusal to guess.

Installing the skill and running a first repair

The skill directory is a clone of the repository, placed into whatever skills root your harness uses. The README gives two examples. Pick the one matching your agent, then restart the agent so it reloads skill metadata.

# Codex
git clone https://github.com/chen0416ccc-cpu/codex-windows-fast-patch-skill.git "$env:USERPROFILE\.codex\skills\codex-windows-fast-patch"

# Claude Code
git clone https://github.com/chen0416ccc-cpu/codex-windows-fast-patch-skill.git "$env:USERPROFILE\.claude\skills\codex-windows-fast-patch"

The README notes that the full history is about 800 KB, smaller than the working tree. If your harness installs skills through a plugin or marketplace mechanism, that copy is not a git working tree and the self-update feature is unavailable.

After the clone, you do not run the scripts by hand. You describe the symptom to the agent and let it load SKILL.md and choose a script. For example, asking the agent to fix the missing plugin marketplace should lead it to scripts/patch_codex_fast_mode_windows_msix.ps1, while a missing phone remote-control entry leads to scripts/patch-remote-control-windows-msix.ps1. The scripts are reference implementations; the README lists them as the workflow the agent follows, and several accept flags such as -VerifyOnly, -Json and -Rollback where the README documents them.

For the restriction-removal case the README gives a plain-language trigger rather than a command: ask the agent to configure the restriction-removal files and the related settings in config.toml. The README states the default behaviour of the session-sync script is not to modify config.toml and not to modify workspace or project roots.

Where the skill refuses to work, and when that is correct

The limits are stated more plainly than most projects state theirs. Windows only. The README says the skill depends on the Windows Store / MSIX package structure, PowerShell, Get-AppxPackage, makeappx.exe, signtool.exe, Windows user environment variables and the Windows Computer Use helper paths, and that macOS needs a separate implementation covering the .app bundle, ASAR unpack and repack, codesign or quarantine, shell scripts and macOS-specific Computer Use gating. Running the Windows scripts on macOS is not a degraded experience; it is the wrong tool.

The hash gating is the second limit and the one most likely to bite. Patches apply only to the exact source and helper hashes the README lists. A new Codex Desktop build with a changed helper will not be patched, and the scripts are described as failing rather than attempting a best-effort match. The native app-server replacement has the same shape: the README documents built-in mappings for Desktop 26.715.2305.0 with 0.145.0-alpha.18 and Desktop 26.707.3748.0 with 0.144.0-alpha.4, both verified end to end on a phone, plus a historical 0.142.4 patch verified only through clean patch-apply. Any other version requires a strictly matching -CodexSourceRef, -AppServerVersion and a verified -PatchPathOverride. The README explicitly says the 0.142.4 patch must not be described as fully compiled or end-to-end verified.

Model entries are the third boundary. If the Fast Mode patch is expected to add a model that is not in the version directory, it will not, and reapplying cannot help. Finally, the -OnlyComputerUseSurface mode cannot be combined with other targeted modes, marketplace registration or Fast Mode verification, and the README notes the test scripts do not replace real Desktop approval and screenshot acceptance.

Alternatives: manual ASAR patching or a macOS-oriented workflow

The direct alternative is doing it yourself: unpack app.asar from the MSIX payload, edit the bundle, repack with asar pack, rewrite the integrity table and reinstall the package. That is what the scripts do, and the README's own library description shows why it is unpleasant: the integrity table must be rewritten and read back to assert correctness, and a binary that references app.asar with an unparseable table is a hard failure. Doing this by hand after every Store update means repeating the same steps with no idempotence check and no rollback.

The other alternative is a macOS implementation of the same idea. That is a different approach, not a port: the README says macOS needs its own flow for the Codex .app bundle, ASAR unpack and repack, codesign or quarantine and shell scripts, plus its own Computer Use availability gating. If you work on macOS, this repository is not a starting point you can adapt by swapping paths.

A third option is to stop patching and use the unmodified Desktop build. That is legitimate if you do not need Fast Mode, the plugin marketplace, Computer Use or the phone remote-control entry. The skill exists because those toggles are local and get reset; if you never enabled them, there is nothing to restore.

Maintenance, self-update and licence status

The README states the skill can update itself to the latest version before each repair run, which is the main reason to install it as a git clone rather than through a marketplace. A marketplace copy is not a git working tree and self-update is unavailable there, so you would be pinned to whatever revision was published. The last push to the repository was on 2026-09-16.

The upgrade cost is mostly in the hash profiles. Each new Codex Desktop build can change helper hashes, and the README treats exact hashes as the contract. When a build is not in the built-in mapping, the agent needs a matching -CodexSourceRef, -AppServerVersion and a verified -PatchPathOverride before the native replacement path is usable. Budget for that whenever Desktop updates.

On licensing, the repository has no licence file and no licence identifier is given, so the default position is that no permission has been granted. There is a SECURITY.md in the repository root, but the README does not describe a security policy or a signature-verification requirement for the patches. Anyone redistributing or bundling this into a product should treat the licence question as unresolved and get their own answer; nothing here is legal advice. Note also that signtool.exe appears in the dependency list, which means the workflow touches package signing on your machine.

Editorial conclusion

Adopt it if you run Codex Desktop from the Windows Store or MSIX package and an update has silently dropped Fast Mode, the plugin marketplace, Computer Use or the phone remote-control entry, and you are willing to keep a git clone of the skill so its self-update works. Do not adopt it on macOS: the README states the macOS path needs a separate implementation for the .app bundle, ASAR unpacking, codesign and shell scripts. Before trusting it on your machine, check which Desktop build you are on against the baselines the README lists (26.715.2305.0 and 26.707.3748.0 for the native app-server replacement, the listed 26.7xx and 26.8xx builds for the Win10 Computer Use helper) and confirm your helper hashes match, because the scripts apply patches only to exact hashes and fail otherwise.

Frequently asked questions

Official sources

1. chen0416ccc-cpu/codex-windows-fast-patch-skill on GitHub
2. Issues
3. README