1. The agent drops it
NexusFree.exe, the MCP server running under your account, writes the request to %ProgramData%\NexusFree\inbox, then starts the NexusFree scheduled task.
v1.2.3 · OPEN SOURCE · MIT
Admin rights.
MCP SERVER · SYSTEM · WINDOWS
Admin rights.
No UAC prompt.
Administrator and SYSTEM commands for your AI coding agents on Windows.
An agent working in the background cannot answer a UAC prompt, so sfc, dism, services, HKLM keys, drivers or installers fail. NexusFree runs those commands under SYSTEM for one Windows account, the one that installed it, after a single elevation at install time. One MCP server, shared by Claude Code, Codex and Antigravity.
What this means. Installing NexusFree turns that account into one that can act as SYSTEM without confirming each time: any program running under it, not only your AI agents, can use it. Install it only on a PC you own, for an account you already use as an administrator, and treat the agents’ commands as you would your own. Other Windows accounts on the PC get no access.
- One authorized account
- One UAC prompt, at install time
- Every command logged
Works with
free(command, timeout_seconds=600)- a PowerShell command line, run under SYSTEM
exit codeand output: stdout, then stderrfree_status()- are the SYSTEM task and the spool installed
MCP/C# .NET 10/SYSTEM/WINDOWS/X64 · ARM64/MIT
01 / WHAT IT DOES
Two tools.
One account.
The same for Claude Code, Codex and Antigravity: run a command under SYSTEM, check the installation.
freeRuns a PowerShell command line under SYSTEM and returns its exit code and output (stdout, then stderr). Default timeout: 600 s.
free_statusTells whether the SYSTEM task and the spool are installed.
--status, --exec, --versionThe NexusFree.exe engine also works from the command line: status, running a command, version.
01 / HOW IT WORKS
One request.
One SYSTEM task. One answer.
2. The SYSTEM task picks it up
Its only action, the dispatcher Dispatch-NexusFree.ps1 installed in %ProgramFiles%\NexusFree, moves the request out of the inbox.
3. Check, then run
It checks that the request file belongs to the authorized account, then runs the command under SYSTEM.
4. The answer comes back
It writes the answer to outbox, which the agent receives. Every command is written to logs\elevation.log.
Native C# engine (.NET 10), stdio MCP server. Access rights are set by SID, so installation works in any Windows display language.
02 / INSTALLATION
One message.
A single UAC prompt.
Before you install. The account that installs NexusFree will be able to act as SYSTEM without confirming each time, and so will any program running under it. Only on a PC you own, for an account that is already an administrator.
Requirements
- Windows 10 or 11, as the account that will use it (not another account’s elevated prompt)
- An account you already use as an administrator, on a PC you own
- Claude Code, Codex and/or Antigravity
Ask your AI
Paste this message into Claude Code, Codex or Antigravity: it follows the NexusSystem guide and installs NexusFree. The Nexus pack never installs it on its own: only when it is named.
Install NexusFree by following https://raw.githubusercontent.com/pironjulien/NexusSystem/main/INSTALL-AI.mdOr the NexusSystem app
Free on the Microsoft Store, no account: it shows your AI apps and installs NexusFree with one button.
Accept the UAC prompt, once
The SYSTEM side needs one UAC prompt; later updates go through NexusFree itself. Claude Code and Codex get the plugin from the NexusSystem catalog; the installation declares it to Antigravity.
Restart your AI apps
Quit them completely so they load the new MCP server.
Check
Ask your AI for NexusFree’s status: the free_status tool tells whether the SYSTEM task and the spool are installed.
Or by hand, from the repository
In PowerShell, as the account that will use it: clone the repository and run the installer.
git clone https://github.com/pironjulien/NexusFree
powershell -NoProfile -ExecutionPolicy Bypass -File NexusFree\install.ps1 -ApplyFrom the source, the installer builds the engine with the .NET 10 SDK; from a release package (NexusFree-win-x64.zip or NexusFree-win-arm64.zip, checked against its SHA256SUMS.txt), the engine is already built. Details: repository README.
Uninstall
From an elevated prompt:
Unregister-ScheduledTask -TaskName NexusFree -Confirm:$false
Remove-Item -Recurse -Force "$env:ProgramFiles\NexusFree", "$env:ProgramData\NexusFree"Then remove %USERPROFILE%\.nexus\nexus-free and the nexus-free plugin from your AI apps.
Or the whole Nexus pack, at once
Paste this message into your AI: it follows the NexusSystem guide, offers the Nexus products that suit your PC, installs each one with its official installer, then checks the result. NexusFree is included only if you name it. Or the NexusSystem, free on the Microsoft Store.
Install Nexus for me by following https://raw.githubusercontent.com/pironjulien/NexusSystem/main/INSTALL-AI.mdCode, documentation and installer: NexusFree GitHub repository.
Independent project, not affiliated with Microsoft, Anthropic, OpenAI or Google.
- Version
- 1.2.3
- Licence
- MIT
- System
- Windows 10 or 11, x64 or Arm64
- Clients
- Claude Code, Codex, Antigravity
- Engine
- Native C# (.NET 10), stdio MCP server
- Checks
- test.ps1: xUnit suite (MCP protocol), no elevation needed
03 / NEXUS ECOSYSTEM
On its own, it works.
Together, it does more.
NexusFree installs on its own, or with the other Nexus bricks, each one à la carte.
NexusSystem
WithNexusSystem installs NexusFree when you name it; Claude Code and Codex get its plugin from the Nexus catalog.
Withoutinstall.ps1, from the repository, installs NexusFree and declares it to Antigravity.
Discover NexusSystemThe other Nexus bricks
Each one installs on its own, à la carte, with its own installer.
04 / SECURITY
Powerful.
And said plainly.
NexusFree removes UAC as a confirmation step for one account: it is not a sandbox and does not judge commands.
The authorized account acts as SYSTEM
By design, the authorized account can act as SYSTEM without a prompt. Any program that runs under that account, malicious or not, can do so too, the same way it could use an elevated prompt left open. Install it only for an account that is already an administrator, on a PC you control.
Other accounts, shut out
The spool %ProgramData%\NexusFree has a protected ACL, with nothing inherited: only SYSTEM, Administrators and the authorized account can write requests, read answers or start the task. The dispatcher also refuses a request whose file is not owned by the authorized account, Administrators or SYSTEM.
Every command logged
Every command line is written to %ProgramData%\NexusFree\logs\elevation.log: do not pass secrets on the command line.
Trusted updates
install.ps1 -Apply, sent through an installed NexusFree, replaces the dispatcher under SYSTEM: run it only from a copy you trust, a release whose files match its SHA256SUMS.txt and build attestation, or the repository.
Immutable releases
GitHub releases are immutable: their files and tag cannot be replaced. Every file carries a build provenance attestation.
Report a vulnerability privately
Through GitHub private vulnerability reporting, never in a public issue. First answer within 3 days; a confirmed vulnerability is fixed in a new release, usually within 30 days.
Who can access what
The access rights set at install time, by SID.
| Path | SYSTEM, Administrators | Authorized account | Other accounts |
|---|---|---|---|
%ProgramFiles%\NexusFree (dispatcher, config.json) | full | read | read |
%ProgramData%\NexusFree\inbox, outbox | full | modify | none |
%ProgramData%\NexusFree\logs | full | read | none |
%ProgramData%\NexusFree\staging | full | none | none |
| NexusFree scheduled task | full | read, run | none |
05 / GOOD TO KNOW
Honest.
Limits included.
Not a sandbox
NexusFree does not judge the commands it runs: treat the agents’ commands as you would your own.
One Windows account
The one that ran the installation. Other accounts on the PC get no access, and only the latest release is supported.
SYSTEM has its own profile
Its environment variables and user folder are not yours: use absolute paths. A timeout on the AI side does not necessarily cancel the command.
06 / LINKS
Read the code.
Before you install it.
The engine, the dispatcher, the installer, the tests and the security policy are on GitHub, under the MIT licence.