Summary

uv tool update-shell is updating the PATH in registry, but it seems Windows is not aware it needs to reload the change.

Version: uv 0.9.18 (0cee764 2025-12-16)
Context: Windows 10 22H2

Steps to reproduce

1. Ensure %SYSTEMPROFILE%\.local\bin is not already included in %PATH%.
2. Install any uv tool, like uv tool install jtbl.
3. Run uv tool update-shell.
4. Open a fresh cmd.exe and try to run the tool, like jtbl.

Expected result

The tool runs.

Current result

The tool is not found.

Workaround

Before step 4, in Control Panel "System Properties", click "Environment Variables..." then "Ok".

Explanation

uv tool update-shell is updating the PATH in registry, but it seems Windows is not aware it needs to reload the change.

One way to do this is to broadcast WM_SETTINGCHANGE to the system. Here's a PowerShell example that works for me:

$windowBroadcastHandle = [IntPtr]0xffff
$wmSettingChangeMessageId = 0x1A
$environmentChangedParameter = "Environment"
$abortIfHungFlag = 0x0002

Add-Type @"
using System;
using System.Runtime.InteropServices;

public static class NativeMethods
{
    [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    public static extern IntPtr SendMessageTimeout(
        IntPtr windowHandle,
        int messageId,
        IntPtr wParam,
        string lParam,
        int flags,
        int timeoutMilliseconds,
        out IntPtr result);
}
"@

[NativeMethods]::SendMessageTimeout(
    $windowBroadcastHandle,
    $wmSettingChangeMessageId,
    [IntPtr]::Zero,
    $environmentChangedParameter,
    $abortIfHungFlag,
    5000,
    [ref]([IntPtr]::Zero)
)

Platform

Windows 10 22H2

Version

uv 0.9.18 (0cee764 2025-12-16)

Python version

Python 3.14.2