A PowerShell script (for Windows), that updates the environment variables; not only the process but the user's environment variables

pwsh.ps1

$envs = @{
    #"CHROME_EXECUTABLE" = "%ProgramFiles%\Google\Chrome Dev\Application\chrome.exe"
    "PACKAGES_ROOT" = "D:\.packages"
    "PUB_CACHE" = "%PACKAGES_ROOT%\pub"
    "npm_config_cache" = "%PACKAGES_ROOT%\npm"
    "NUGET_PACKAGES" = "%PACKAGES_ROOT%\nuget"
    "BUN_INSTALL_CACHE_DIR" = "%PACKAGES_ROOT%\bun\install\cache"
    "VCPKG_DEFAULT_BINARY_CACHE" = "%PACKAGES_ROOT%\vcpkg"
    "PIP_CACHE_DIR" = "%PACKAGES_ROOT%\pip"
    "GRADLE_USER_HOME" = "%PACKAGES_ROOT%\.gradle"
    "MAVEN_OPTS" = "-Dmaven.repo.local=%PACKAGES_ROOT%\maven %MAVEN_OPTS%"
    "JAVA_HOME"="%ProgramFiles%\Android\Android Studio\jbr"
    "CLAUDE_CODE_GIT_BASH_PATH"="%ProgramFiles%\git\bin\bash.exe"
}

$path = @(
    "%USERPROFILE%\.bun\bin"
    "%USERPROFILE%\.local\bin"
    "D:\flutter\bin"
    "%LOCALAPPDATA%\Android\Sdk\platform-tools"
    "%PUB_CACHE%\bin"
    "%JAVA_HOME%\bin"
)

# Function to expand environment variables in a string
function Expand-EnvironmentVariables {
    param([string]$Value)
    return [System.Environment]::ExpandEnvironmentVariables($Value)
}

# Function to broadcast environment variable changes
function Send-EnvironmentChangeMessage {
    if (-not ('Win32.NativeMethods' -as [type])) {
        Add-Type -Namespace Win32 -Name NativeMethods -MemberDefinition @'
[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
public static extern IntPtr SendMessageTimeout(
    IntPtr hWnd, uint Msg, UIntPtr wParam, string lParam,
    uint fuFlags, uint uTimeout, out UIntPtr lpdwResult);
'@
    }

    $HWND_BROADCAST = [IntPtr]0xffff
    $WM_SETTINGCHANGE = 0x1a
    $result = [UIntPtr]::Zero

    [Win32.NativeMethods]::SendMessageTimeout(
        $HWND_BROADCAST,
        $WM_SETTINGCHANGE,
        [UIntPtr]::Zero,
        "Environment",
        2, # SMTO_ABORTIFHUNG
        5000,
        [ref]$result
    ) | Out-Null
}

# Set environment variables to User registry (without expansion)
$changesCount = 0
foreach ($entry in $envs.GetEnumerator()) {
    $key = $entry.Key
    $value = $entry.Value

    # Check if the value is different from current registry value (unexpanded)
    $regKey = [Microsoft.Win32.Registry]::CurrentUser.OpenSubKey("Environment", $false)
    $currentValue = if ($regKey) {
        $regKey.GetValue($key, $null, [Microsoft.Win32.RegistryValueOptions]::DoNotExpandEnvironmentNames)
    } else {
        $null
    }
    if ($regKey) { $regKey.Close() }

    if ($currentValue -ne $value) {
        # Determine registry type based on whether value contains expandable variables
        $regType = if ($value -match '%\w+%') { 'ExpandString' } else { 'String' }

        # Set in user registry using Set-ItemProperty
        Set-ItemProperty -Path "HKCU:\Environment" -Name $key -Value $value -Type $regType
        $changesCount++
    }

    # Expand for display and current process
    $expandedValue = Expand-EnvironmentVariables $value

    # Set in current process (expanded)
    Set-Item -Path "env:$key" -Value $expandedValue
}

# Get current user PATH from registry (unexpanded)
$regKey = [Microsoft.Win32.Registry]::CurrentUser.OpenSubKey("Environment", $false)
$currentUserPath = if ($regKey) {
    $regKey.GetValue("Path", "", [Microsoft.Win32.RegistryValueOptions]::DoNotExpandEnvironmentNames)
} else {
    ""
}
if ($regKey) { $regKey.Close() }

# Convert to array and filter out empties
$pathArray = if ($currentUserPath) {
    $currentUserPath -split ';' | Where-Object { $_ -ne '' }
} else {
    @()
}

# Add new paths if they don't already exist (compare expanded versions)
$pathModified = $false
$expandedPathArray = $pathArray | ForEach-Object { Expand-EnvironmentVariables $_ }
$newPathArray = @()
foreach ($newPath in $path) {
    $expandedNewPath = Expand-EnvironmentVariables $newPath
    if ($expandedPathArray -notcontains $expandedNewPath) {
        $newPathArray += $newPath
        $expandedPathArray += $expandedNewPath
        $pathModified = $true
    }
}

# Update user PATH in registry if modified
if ($pathModified) {
    $newUserPath = ($newPathArray + $pathArray) -join ';'
    Set-ItemProperty -Path "HKCU:\Environment" -Name "Path" -Value $newUserPath -Type ExpandString
    $changesCount++
}

# Update current process PATH with expanded values
$processPathArray = @()
foreach ($p in $pathArray) {
    $expanded = Expand-EnvironmentVariables $p
    if ($expanded) {
        $processPathArray += $expanded
    }
}

# Add existing system paths to avoid breaking current session
$systemPath = [System.Environment]::GetEnvironmentVariable("Path", [System.EnvironmentVariableTarget]::Machine)
if ($systemPath) {
    $systemPaths = $systemPath -split ';' | Where-Object { $_ -ne '' }
    foreach ($sysPath in $systemPaths) {
        if ($processPathArray -notcontains $sysPath) {
            $processPathArray += $sysPath
        }
    }
}

$env:Path = $processPathArray -join ';'

# Broadcast the environment change to all windows only if changes were made
if ($changesCount -gt 0) {
    Send-EnvironmentChangeMessage
}