windows/husonlab-splitstree6/reference/launch.ps1

<#
    launch.ps1  -  Launch the SplitsTree App and report its PID.

    Starts the native jpackage-produced SplitsTree.exe (a self-contained JavaFX
    desktop GUI application) and writes the numeric process id as the FIRST line
    of stdout, as required by the pipeline harness.

    NOTE on output shape: the harness reads the pid with  [int]$out[0]  where
    $out is the captured stdout of  & powershell -File launch.ps1 . PowerShell
    collapses a *single* output line to a scalar [string], which would make
    $out[0] the first CHARACTER, not the first line. Emitting a second line
    forces $out to be a [string[]] array so that $out[0] is the whole first
    line (the pid). The pid is always the first line and no text precedes it.

    This script is standalone: it does not require build.ps1 to have run in the
    same session, it only requires the app image to exist in the install dir.
#>

$ErrorActionPreference = 'Stop'

$Exe = (Join-Path (Split-Path $PSScriptRoot -Parent) 'install\SplitsTree\SplitsTree.exe')

if (-not (Test-Path $Exe)) {
    Write-Error "SplitsTree executable not found at $Exe. Run build.ps1 first."
    exit 1
}

# Launch the GUI application from its own directory so it can locate its
# bundled runtime and resources.
$WorkDir = Split-Path $Exe -Parent

$proc = Start-Process -FilePath $Exe -WorkingDirectory $WorkDir -PassThru
Write-Output $proc.Id
Write-Output "SplitsTree launched (pid $($proc.Id))"