sipherxyz/live-coding-refresh

Live Coding Refresh Skill

Role: Build Engineer - Live Coding Trigger Scope: Trigger Unreal Engine Live Coding compilation Engine Version: UE 5.7+ Platform: Windows

Objective

Trigger Live Coding (Hot Reload) compilation in Unreal Editor by sending Ctrl+Alt+F11 keystroke, allowing code changes to be compiled without restarting the editor.

Prerequisites

1. Unreal Editor must be running with the project open
2. Live Coding must be enabled in Editor Preferences
3. No compile errors in the code

Usage

When the user asks to:

• "live reload"
• "hot reload"
• "refresh code"
• "trigger live coding"
• "compile with live coding"

Workflow

Step 1: Check if Editor is Running

$editor = Get-Process -Name "UnrealEditor" -ErrorAction SilentlyContinue
if (-not $editor) {
    Write-Host "ERROR: Unreal Editor is not running. Please open the editor first."
    exit 1
}
Write-Host "Found Unreal Editor process (PID: $($editor.Id))"

Step 2: Send Ctrl+Alt+F11 Keystroke

# Load Windows Forms for SendKeys
Add-Type -AssemblyName System.Windows.Forms

# Find the Unreal Editor window
$editor = Get-Process -Name "UnrealEditor" -ErrorAction SilentlyContinue
if ($editor) {
    # Bring editor to foreground
    Add-Type @"
    using System;
    using System.Runtime.InteropServices;
    public class Win32 {
        [DllImport("user32.dll")]
        public static extern bool SetForegroundWindow(IntPtr hWnd);
        [DllImport("user32.dll")]
        public static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
    }
"@

    $hwnd = $editor.MainWindowHandle
    [Win32]::ShowWindow($hwnd, 9)  # SW_RESTORE
    [Win32]::SetForegroundWindow($hwnd)

    Start-Sleep -Milliseconds 500

    # Send Ctrl+Alt+F11
    [System.Windows.Forms.SendKeys]::SendWait("^%{F11}")

    Write-Host "SUCCESS: Sent Ctrl+Alt+F11 to Unreal Editor"
    Write-Host "Live Coding compilation triggered. Check editor for results."
} else {
    Write-Host "ERROR: Could not find Unreal Editor window"
    exit 1
}

Complete Script

Save as trigger-live-coding.ps1:

# Trigger Live Coding in Unreal Editor
# Sends Ctrl+Alt+F11 to the editor window

param(
    [switch]$WaitForCompletion
)

# Check if editor is running
$editor = Get-Process -Name "UnrealEditor" -ErrorAction SilentlyContinue
if (-not $editor) {
    Write-Host "ERROR: Unreal Editor is not running." -ForegroundColor Red
    Write-Host "Please open the editor first, or use 'dev-workflow:ue-cpp-build' skill for standalone compilation."
    exit 1
}

Write-Host "Found Unreal Editor (PID: $($editor.Id))" -ForegroundColor Green

# Load required assemblies
Add-Type -AssemblyName System.Windows.Forms

# Import Win32 functions
Add-Type @"
using System;
using System.Runtime.InteropServices;
public class Win32User {
    [DllImport("user32.dll")]
    public static extern bool SetForegroundWindow(IntPtr hWnd);
    [DllImport("user32.dll")]
    public static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
    [DllImport("user32.dll")]
    public static extern IntPtr GetForegroundWindow();
}
"@

# Store current foreground window to restore later
$previousWindow = [Win32User]::GetForegroundWindow()

# Bring editor to foreground
$hwnd = $editor.MainWindowHandle
if ($hwnd -eq [IntPtr]::Zero) {
    Write-Host "WARNING: Could not get editor window handle. Trying anyway..." -ForegroundColor Yellow
}

[Win32User]::ShowWindow($hwnd, 9)  # SW_RESTORE
[Win32User]::SetForegroundWindow($hwnd)

# Wait for window to come to foreground
Start-Sleep -Milliseconds 300

# Send Ctrl+Alt+F11
Write-Host "Sending Ctrl+Alt+F11..." -ForegroundColor Cyan
[System.Windows.Forms.SendKeys]::SendWait("^%{F11}")

Write-Host "Live Coding triggered!" -ForegroundColor Green
Write-Host ""
Write-Host "Check the Unreal Editor for compilation results."
Write-Host "The Live Coding panel will show compilation progress."

# Restore previous window if requested
if (-not $WaitForCompletion) {
    Start-Sleep -Milliseconds 500
    [Win32User]::SetForegroundWindow($previousWindow)
}

exit 0

Execution Command

powershell -NoProfile -ExecutionPolicy Bypass -File "{ProjectRoot}/./trigger-live-coding.ps1"

Limitations

1. Cannot capture compilation output - Live Coding runs inside the editor, so we can't see the compilation results from the command line
2. No error reporting - If compilation fails, you need to check the editor's Live Coding panel
3. Window focus - Briefly brings editor to foreground to receive the keystroke
4. Editor must be responsive - If editor is frozen or in a modal dialog, the keystroke won't work

When to Use

| Scenario | Use Live Coding | Use /dev-workflow:ue-cpp-build | |----------|-----------------|------------------| | Editor is open, small code change | Yes | No | | Editor is closed | No | Yes | | Header file changes | No (restart needed) | Yes | | Adding new UPROPERTY/UFUNCTION | No (restart needed) | Yes | | Implementation-only changes | Yes | Either | | Need to see compile output | No | Yes |

Troubleshooting

"Editor not running"

• Open the Unreal Editor with your project first
• Use open-editor skill to launch it

"Live Coding failed"

• Check the Live Coding panel in editor (Window > Live Coding)
• Look for compile errors
• Some changes require full editor restart (header changes, new UPROPERTYs)

"Keystroke not received"

• Editor might be in a modal dialog
• Try clicking on the editor first
• Check if Live Coding is enabled in Editor Preferences

Related Skills

• /dev-workflow:ue-cpp-build - Full compilation when editor is closed
• open-editor - Launch Unreal Editor

Legacy Metadata

skill: live-coding-refresh
invoke: /dev-workflow:live-coding-refresh