fix: track Windows local process trees safely

tests/local-dev.tests.ps1

@@ -63,6 +63,43 @@ try {
     Assert-Equal './cmd/worker' $commands.Worker.Arguments[1] 'Worker command should follow the backend contract'
     Assert-Equal 'run' $commands.Frontend.Arguments[0] 'Frontend should use its checked-in dev script'
 
+    $stateDirectory = Join-Path $fixture '.local'
+    New-Item -ItemType Directory -Path $stateDirectory -Force | Out-Null
+    $currentProcess = Get-Process -Id $PID
+    @([pscustomobject]@{
+        Name = 'test-host'
+        Pid = $currentProcess.Id
+        StartTimeUtc = $currentProcess.StartTime.ToUniversalTime().ToString('o')
+    }) | ConvertTo-Json | Set-Content -LiteralPath (Join-Path $stateDirectory 'processes.json') -Encoding utf8
+    $status = @(Get-LocalDevStatus -DeploymentPath $fixture)
+    Assert-Equal $true $status[0].Running 'Status should recognize a recorded live process after JSON date conversion'
+
+    $childTreeRoot = Start-Process -FilePath 'cmd.exe' -ArgumentList @('/c', 'powershell.exe -NoProfile -Command "Start-Sleep -Seconds 60"') -WindowStyle Hidden -PassThru
+    try {
+        $childTreeRoot.Refresh()
+        @([pscustomobject]@{
+            Name = 'test-tree'
+            Pid = $childTreeRoot.Id
+            StartTimeUtc = $childTreeRoot.StartTime.ToUniversalTime().ToString('o')
+        }) | ConvertTo-Json | Set-Content -LiteralPath (Join-Path $stateDirectory 'processes.json') -Encoding utf8
+
+        $deadline = [DateTime]::UtcNow.AddSeconds(5)
+        do {
+            $child = Get-CimInstance Win32_Process -Filter "ParentProcessId=$($childTreeRoot.Id)" -ErrorAction SilentlyContinue | Select-Object -First 1
+            if (-not $child) { Start-Sleep -Milliseconds 50 }
+        } while (-not $child -and [DateTime]::UtcNow -lt $deadline)
+        if (-not $child) { throw 'Test child process did not start' }
+
+        Stop-LocalDev -DeploymentPath $fixture
+        Assert-Equal $null (Get-Process -Id $childTreeRoot.Id -ErrorAction SilentlyContinue) 'Stop should terminate the recorded wrapper process'
+        Assert-Equal $null (Get-Process -Id $child.ProcessId -ErrorAction SilentlyContinue) 'Stop should terminate descendants of the recorded wrapper process'
+    }
+    finally {
+        if (Get-Process -Id $childTreeRoot.Id -ErrorAction SilentlyContinue) {
+            & taskkill.exe /PID $childTreeRoot.Id /T /F | Out-Null
+        }
+    }
+
     Remove-Item -LiteralPath (Join-Path $backend 'cmd\worker') -Recurse
     Assert-Throws { Resolve-LocalDevCommands -BackendPath $backend -FrontendPath $frontend } 'cmd/worker' 'A missing worker entrypoint must be actionable'