mcpproxy doesn't see environment variables on windows

[andreimirt]

I used the binary installer to install on windows.
I imported some working mcps from claude.
The http ones work just fine. The stdio ones don't.
All the mcps that don't work have a line like this:
"message": "2026-02-10T12:32:28.318+02:00 | INFO | core/monitoring.go:27 | stderr | {"server": "qgis_mcp", "message": "'uv' is not recognized as an internal or external command,"}",

So uv can't be found, but I can run uv just fine from cmd, powershell, even git bash without providing the full path. Also, mcps work in claude, gemini, etc.
I have no clue why mcp-proxy can't find uv..
Same story with any other stdio mcp, even if it's not uv based.
Is there an option that I'm missing that says "ignore user environment"?

[andreimirt]

there's definitely an issue with how PATH is passed over. It is probably sanitized and something I have in PATH breaks it.

This feels quite personal, but here is how my PATH looks like, if anyone wants to try it out.

C:\Program Files\Common Files\Oracle\Java\javapath;C:\Program Files (x86)\Intel\iCLS Client\;C:\Program Files\Intel\iCLS Client\;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\WINDOWS\System32\OpenSSH\;C:\Program Files (x86)\ATI Technologies\ATI.ACE\Core-Static;C:\Program Files (x86)\Gpg4win\..\GnuPG\bin;C:\Program Files\dotnet\;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Git\cmd;C:\Program Files\Microsoft VS Code\bin;C:\Program Files (x86)\glab;C:\Program Files\SafeNet\Authentication\SAC\x64;C:\Program Files\SafeNet\Authentication\SAC\x32;C:\Program Files\Docker\Docker\resources\bin;C:\tools\geckodriver-v0.36.0-win64;C:\Program Files\Positron\bin;C:\ProgramData\anaconda3\Scripts;C:\ProgramData\anaconda3\Library\bin;C:\ProgramData\anaconda3;C:\Program Files (x86)\glab;C:\tools\gitlab-mcp;C:\Program Files\nodejs\;C:\ProgramData\chocolatey\bin;C:\Program Files\R\R-4.5.1\bin\x64;C:\Program Files\Go\bin;C:\Program Files\MCPProxy;C:\Program Files\PowerToys\DSCModules\;C:\Program Files\MCPProxy;C:\Users\AndreiMirt\.local\bin;C:\Users\AndreiMirt\AppData\Local\Microsoft\WindowsApps;C:\Program Files\mitmproxy\bin;C:\ProgramData\anaconda3;C:\ProgramData\anaconda3\Scripts;C:\ProgramData\anaconda3\Library\bin;C:\Users\AndreiMirt\AppData\Roaming\npm;C:\Program Files (x86)\Nmap;C:\Users\AndreiMirt\AppData\Local\Google\Cloud SDK\google-cloud-sdk\bin;C:\Users\AndreiMirt\AppData\Local\Programs\Antigravity\bin;C:\Users\AndreiMirt\go\bin;C:\tools\gitlab-mcp;

[andreimirt]

One other related issue is that the config can't deal with spaces in command.

Not parsed correctly
mcp_config.json:

...
            "command": C:\\my mcps\\mcp.bat"
...

I created a dummy mcp to dump the environment and it looks like below. The PATH is being reconstructed and filtered, but for me it filters uv path, which kind of sucks.

========================================= 
Environment dump at 10/02/2026 14:32:49.27 
========================================= 
APPDATA=C:\Users\AndreiMirt\AppData\Roaming
ComSpec=C:\WINDOWS\system32\cmd.exe
GITLAB_TOKEN=glpat-haha-no!
LOCALAPPDATA=C:\Users\AndreiMirt\AppData\Local
PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.JS;.WS;.MSC
ProgramFiles=C:\Program Files
PROMPT=$P$G
SystemRoot=C:\WINDOWS
TEMP=C:\Users\ANDREI~1\AppData\Local\Temp
TMP=C:\Users\ANDREI~1\AppData\Local\Temp
USERNAME=AndreiMirt
USERPROFILE=C:\Users\AndreiMirt
UV_CACHE_DIR=C:\uvcache
UV_ROOT=C:\Users\AndreiMirt\.local\bin
PATH=C:\Windows\System32;C:\Windows;C:\Program Files\Docker\Docker\resources\bin;C:\Program Files\Git\bin;C:\Program Files\nodejs;C:\Users\AndreiMirt\AppData\Roaming\npm
 
========================================= 
End of environment dump 
=========================================