Powershell-Copilot-Standards style-enforcement.instructions.md

PowerShell Style Guide Enforcement

Automatically enforce PowerShell community style guidelines in all code generation.

Worked example: every file under Documentation/Examples is written to these rules and passes the repository's own quality gates. When the wording here is ambiguous, match the examples.

Mandatory Style Patterns

Code Formatting

• Brace Style: One True Brace Style (opening brace at end of line)
• Indentation: 4 spaces, never tabs
• Line Length: Maximum 115 characters
• Blank Lines: 2 blank lines before functions, 1 between methods

A team that wants these checked mechanically does not need a settings file - PSScriptAnalyzer ships CodeFormattingOTBS, which already configures the brace style, 4-space indentation, whitespace and assignment alignment above:

Invoke-ScriptAnalyzer -Path . -Recurse -Settings CodeFormattingOTBS

The 115-character limit is the one rule it does not include; add PSAvoidLongLines if the team wants it enforced. Adopting either is their choice - these standards describe the practices, not the audit configuration.

Parameter Formatting

# Correct parameter block formatting
param(
    [Parameter(Mandatory = $true,
               ValueFromPipeline = $true,
               ValueFromPipelineByPropertyName = $true)]
    [ValidateNotNullOrEmpty()]
    [string[]]$ComputerName,

    [Parameter()]
    [System.Management.Automation.PSCredential]
    [System.Management.Automation.Credential()]
    $Credential = [System.Management.Automation.PSCredential]::Empty
)

Operator Spacing

# Correct spacing around operators
$result = $value1 + $value2
$condition = ($status -eq 'Running') -and ($service -ne $null)

# Correct parameter spacing
Get-Process -Name "powershell" -ComputerName $servers

Anti-Patterns to Avoid

# Avoid backticks for line continuation
# Instead of:
Get-WmiObject -Class Win32_LogicalDisk `
              -Filter "DriveType=3" `
              -ComputerName $server

# Use splatting:
$params = @{
    Class = 'Win32_LogicalDisk'
    Filter = 'DriveType=3'
    ComputerName = $server
}
Get-WmiObject @params

# Avoid Write-Host unless specifically needed for colored output
# Use Write-Output, Write-Verbose, Write-Information instead