scripts fixes

start.ps1

@@ -24,12 +24,19 @@ $VenvPython = Join-Path $GuiDir ".venv\Scripts\python.exe"
 $AppScript  = Join-Path $Root  "apps\gui\app.py"
 $EnvFile    = Join-Path $Root  ".env"
 $EnvExample = Join-Path $Root  ".env.example"
+$LogFile    = Join-Path $Root  "start_log.txt"
+
+# Write all output to log file so errors are readable even if window closes
+Start-Transcript -Path $LogFile -Append | Out-Null
+Write-Host "=== start.ps1  $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss')  Mode=$Mode ==="
 
 function Write-Step($msg) { Write-Host "`n==> $msg" -ForegroundColor Cyan }
 function Write-OK($msg)   { Write-Host "    [OK] $msg" -ForegroundColor Green }
 function Write-Warn($msg) { Write-Host "    [!!] $msg" -ForegroundColor Yellow }
 function Write-Fail($msg) {
     Write-Host "`n[FAIL] $msg" -ForegroundColor Red
+    Write-Host "  Log: $LogFile" -ForegroundColor DarkGray
+    try { Stop-Transcript | Out-Null } catch {}
     Write-Host "`n  Press Enter to close..." -ForegroundColor DarkGray
     $null = Read-Host
     exit 1
@@ -38,6 +45,8 @@ function Write-Fail($msg) {
 # Keep window open on any unhandled error
 trap {
     Write-Host "`n[ERROR] $_" -ForegroundColor Red
+    Write-Host "  Log: $LogFile" -ForegroundColor DarkGray
+    try { Stop-Transcript | Out-Null } catch {}
     Write-Host "`n  Press Enter to close..." -ForegroundColor DarkGray
     $null = Read-Host
     exit 1
@@ -266,5 +275,7 @@ if (-not $SkipSpectrometer) {
 Write-Host "  Stop all:           .\stop.ps1"
 Write-Host "  Update code:        .\update.bat"
 Write-Host ""
+Write-Host "  Log saved to: $LogFile" -ForegroundColor DarkGray
+try { Stop-Transcript | Out-Null } catch {}
 Write-Host "  Press Enter to close this window..." -ForegroundColor DarkGray
 $null = Read-Host