diff --git a/playbook/shopfloor-setup/Shopfloor/00-PreInstall-MachineApps.ps1 b/playbook/shopfloor-setup/Shopfloor/00-PreInstall-MachineApps.ps1
index 22714c8..de75a5d 100644
--- a/playbook/shopfloor-setup/Shopfloor/00-PreInstall-MachineApps.ps1
+++ b/playbook/shopfloor-setup/Shopfloor/00-PreInstall-MachineApps.ps1
@@ -184,22 +184,39 @@ foreach ($app in $config.Applications) {
         Write-PreInstallLog "  InstallArgs: $($app.InstallArgs)"
     }
 
+    # Per-app verbose msiexec log path - written by /L*v on MSI installs and tailed
+    # into the runner log on failure so we don't need to dig through C:\Logs manually.
+    $safeName = $app.Name -replace '[^a-zA-Z0-9]','_'
+    $msiLog   = Join-Path $logDir "msi-$safeName.log"
+    if (Test-Path $msiLog) { Remove-Item $msiLog -Force -ErrorAction SilentlyContinue }
+
     try {
-        # Start without -Wait so we can poll. UDC_Setup.exe in particular hangs forever
-        # after install (it spawns UDC.exe and hides its main window without exiting),
-        # so we can't rely on the process exiting on its own.
+        # We use [System.Diagnostics.Process]::Start() directly instead of Start-Process
+        # because PowerShell 5.1's Start-Process -PassThru has a bug where the returned
+        # Process object's OS handle is disposed when control returns to the script,
+        # causing ExitCode to always read as $null even after WaitForExit() succeeds.
+        # Calling Process.Start() directly returns a Process object with a live handle
+        # that exposes ExitCode correctly. We poll HasExited so UDC_Setup.exe (which
+        # hangs forever after spawning a hidden WPF window) can be killed via the
+        # detection-during-install path.
+        $psi = New-Object System.Diagnostics.ProcessStartInfo
+        $psi.UseShellExecute = $false
+        $psi.CreateNoWindow  = $true
+        $psi.WindowStyle     = [System.Diagnostics.ProcessWindowStyle]::Hidden
+
         if ($app.Type -eq "MSI") {
-            $msiArgs = "/i `"$installerPath`""
+            $psi.FileName  = "msiexec.exe"
+            $psi.Arguments = "/i `"$installerPath`""
             if ($app.InstallArgs) {
-                $msiArgs += " " + $app.InstallArgs
+                $psi.Arguments += " " + $app.InstallArgs
             }
-            $proc = Start-Process -FilePath "msiexec.exe" -ArgumentList $msiArgs -PassThru -NoNewWindow
+            $psi.Arguments += " /L*v `"$msiLog`""
+            Write-PreInstallLog "  msiexec verbose log: $msiLog"
         }
         elseif ($app.Type -eq "EXE") {
+            $psi.FileName = $installerPath
             if ($app.InstallArgs) {
-                $proc = Start-Process -FilePath $installerPath -ArgumentList $app.InstallArgs -PassThru -NoNewWindow
-            } else {
-                $proc = Start-Process -FilePath $installerPath -PassThru -NoNewWindow
+                $psi.Arguments = $app.InstallArgs
             }
         }
         else {
@@ -208,6 +225,8 @@ foreach ($app in $config.Applications) {
             continue
         }
 
+        $proc = [System.Diagnostics.Process]::Start($psi)
+
         # Poll for completion: process exit OR detection success (whichever happens first)
         $timeoutSec   = 600   # 10 min hard cap per app
         $pollInterval = 5
@@ -256,16 +275,59 @@ foreach ($app in $config.Applications) {
             Write-PreInstallLog "  SUCCESS (verified via detection during install)"
             $installed++
         }
-        elseif ($proc.ExitCode -eq 0 -or $proc.ExitCode -eq 3010) {
-            Write-PreInstallLog "  Exit code $($proc.ExitCode) after $elapsed s - SUCCESS"
-            if ($proc.ExitCode -eq 3010) {
-                Write-PreInstallLog "  (Reboot required for $($app.Name))"
-            }
-            $installed++
-        }
         else {
-            Write-PreInstallLog "  Exit code $($proc.ExitCode) - FAILED" "ERROR"
-            $failed++
+            # Start-Process -PassThru returns a Process object whose ExitCode is null
+            # until WaitForExit() is called - even if HasExited is already true. Without
+            # this, every install that goes through the exit-code branch gets reported
+            # as "Exit code  - FAILED" (empty) regardless of the real result.
+            try { $proc.WaitForExit() } catch { }
+            $exitCode = $proc.ExitCode
+
+            if ($exitCode -eq 0 -or $exitCode -eq 3010) {
+                Write-PreInstallLog "  Exit code $exitCode after $elapsed s - SUCCESS"
+                if ($exitCode -eq 3010) {
+                    Write-PreInstallLog "  (Reboot required for $($app.Name))"
+                }
+                $installed++
+            }
+            else {
+                Write-PreInstallLog "  Exit code $exitCode - FAILED" "ERROR"
+                # Surface the *meaningful* lines from the verbose msiexec log (not just
+                # the tail, which is rollback/cleanup noise). The actual root-cause lines
+                # are: MSI error notes (Note: 1: <code>), failed action returns (return
+                # value 3), errors logged by custom actions, and any line containing the
+                # word "Error". Grep these out so the runner log shows the smoking gun.
+                if ($app.Type -eq "MSI" -and (Test-Path $msiLog)) {
+                    Write-PreInstallLog "  --- meaningful lines from $msiLog ---"
+                    $patterns = @(
+                        'Note: 1: ',
+                        'return value 3',
+                        'Error \d+\.',
+                        'CustomAction .* returned actual error',
+                        'Failed to ',
+                        'Installation failed',
+                        'Calling custom action',
+                        '1: 2262',  # Database not found
+                        '1: 2203',  # Cannot open database
+                        '1: 2330'   # Insufficient permissions
+                    )
+                    $regex = ($patterns -join '|')
+                    $matches = Select-String -Path $msiLog -Pattern $regex -ErrorAction SilentlyContinue |
+                               Select-Object -First 30
+                    if ($matches) {
+                        foreach ($m in $matches) {
+                            Write-PreInstallLog "    $($m.Line.Trim())"
+                        }
+                    } else {
+                        Write-PreInstallLog "    (no error patterns matched - falling back to last 25 lines)"
+                        Get-Content $msiLog -Tail 25 -ErrorAction SilentlyContinue | ForEach-Object {
+                            Write-PreInstallLog "    $_"
+                        }
+                    }
+                    Write-PreInstallLog "  --- end MSI log scan ---"
+                }
+                $failed++
+            }
         }
     } catch {
         Write-PreInstallLog "  Install threw: $_" "ERROR"