diff --git a/scripts/dev-launch.ps1 b/scripts/dev-launch.ps1
new file mode 100644
index 0000000..8330b20
--- /dev/null
+++ b/scripts/dev-launch.ps1
@@ -0,0 +1,83 @@
+<#
+.SYNOPSIS
+    Dev launcher: starts the service in one window and the GUI in another, both
+    pointing at an isolated data root so production %ProgramData% is not touched.
+
+.DESCRIPTION
+    MUST be run from an elevated PowerShell — the admin pipe is ACL'd to SYSTEM
+    and the Administrators group, and a non-elevated process cannot connect.
+#>
+[CmdletBinding()]
+param(
+    [string]$DataRoot = (Join-Path $env:TEMP 'webhook-dev'),
+    [int]$HttpPort = 18080
+)
+
+$ErrorActionPreference = 'Stop'
+$root = Split-Path -Parent $PSScriptRoot
+$servicePath = Join-Path $root 'publish\service\WebhookServer.Service.exe'
+$guiPath     = Join-Path $root 'publish\gui\WebhookServer.Gui.exe'
+
+if (-not (Test-Path $servicePath)) { throw "Service not built. Run: dotnet publish src/WebhookServer.Service -c Release -o publish/service" }
+if (-not (Test-Path $guiPath))     { throw "GUI not built. Run: dotnet publish src/WebhookServer.Gui -c Release -o publish/gui" }
+
+# Verify the current shell is elevated.
+$currentPrincipal = New-Object Security.Principal.WindowsPrincipal([Security.Principal.WindowsIdentity]::GetCurrent())
+if (-not $currentPrincipal.IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)) {
+    throw 'This script must be run from an elevated PowerShell so the GUI can connect to the SYSTEM/Admins-only admin pipe.'
+}
+
+New-Item -ItemType Directory -Path $DataRoot -Force | Out-Null
+New-Item -ItemType Directory -Path (Join-Path $DataRoot 'logs') -Force | Out-Null
+
+$cfgPath = Join-Path $DataRoot 'config.json'
+if (-not (Test-Path $cfgPath)) {
+    $cfg = @"
+{
+  "httpPort": $HttpPort,
+  "trustedProxies": [],
+  "logRetentionDays": 7,
+  "endpoints": [
+    {
+      "id": "11111111-1111-1111-1111-111111111111",
+      "slug": "ping",
+      "description": "Trivial sync hook",
+      "enabled": true,
+      "allowedClients": [],
+      "authMode": "none",
+      "executorType": "windowsPowerShell",
+      "inlineCommand": "Write-Output 'pong'",
+      "executableArgs": [],
+      "dataPassing": { "stdinJson": false, "envVars": false, "argTemplate": false },
+      "responseMode": "sync",
+      "timeoutSeconds": 30,
+      "failOnNonZeroExit": true,
+      "serialize": false
+    }
+  ]
+}
+"@
+    Set-Content -Path $cfgPath -Value $cfg -Encoding utf8
+}
+
+Write-Host "Data root  : $DataRoot"
+Write-Host "Config     : $cfgPath"
+Write-Host "Service exe: $servicePath"
+Write-Host "GUI exe    : $guiPath"
+Write-Host ""
+
+$serviceArgs = @(
+    '-NoExit', '-NoProfile', '-Command',
+    "`$env:WEBHOOKSERVER_DATA = '$DataRoot'; & '$servicePath'"
+)
+Start-Process powershell -ArgumentList $serviceArgs -WindowStyle Normal
+
+Start-Sleep -Seconds 2
+
+# GUI inherits this shell's environment automatically.
+$env:WEBHOOKSERVER_DATA = $DataRoot
+Start-Process -FilePath $guiPath
+
+Write-Host "Service window opened; GUI launched."
+Write-Host "Hit http://localhost:$HttpPort/healthz to confirm Kestrel is up."
+Write-Host "Logs: $(Join-Path $DataRoot 'logs')"