diff --git a/windows/installer/build.ps1 b/windows/installer/build.ps1
index b9d9211..925c3b2 100644
--- a/windows/installer/build.ps1
+++ b/windows/installer/build.ps1
@@ -155,6 +155,15 @@ function Copy-WelcomePayload {
     } else {
         Write-Warning "   No *.json flavour files found in $flavoursDir -- image will ship with no flavours."
     }
+    # --- Guard: verify the payload actually landed in the mounted image -------
+    $stagedExe = Join-Path $dest 'SilverOS.Welcome.App.exe'
+    if (-not (Test-Path $stagedExe)) {
+        throw "Welcome bake failed: SilverOS.Welcome.App.exe missing from image (expected at '$stagedExe'). Check that dotnet publish produced the exe and Copy-Item succeeded."
+    }
+    $stagedFlavours = Get-ChildItem $destFlavours -Filter '*.json' -EA SilentlyContinue
+    if (-not $stagedFlavours) {
+        throw "Welcome bake failed: no flavour manifests staged in '$destFlavours'. Add *.json files under windows/flavours/ or the installed wizard will have no flavour choices."
+    }
     Write-Host "   Welcome payload staged at $dest"
 }
 
diff --git a/windows/tests/Assert-IsoStructure.ps1 b/windows/tests/Assert-IsoStructure.ps1
index e958978..37d9329 100644
--- a/windows/tests/Assert-IsoStructure.ps1
+++ b/windows/tests/Assert-IsoStructure.ps1
@@ -36,6 +36,14 @@ try {
             $mods = Get-ChildItem (Join-Path $mount 'Windows\Setup\Scripts\hardening') -Filter *.ps1 -EA SilentlyContinue
             Assert 'hardening modules baked (>=9 .ps1)' ($mods.Count -ge 9)
             Assert 'Verify script baked' (Test-Path (Join-Path $mount 'Windows\Setup\Scripts\hardening\Verify-SilverMetalWindows.ps1'))
+
+            # Welcome app payload assertions (skipped when Welcome is intentionally disabled).
+            if ($env:SILVERMETAL_WELCOME_ENABLED -ne '0') {
+                $welcomeExe = Join-Path $mount 'Program Files\SilverOS\Welcome\SilverOS.Welcome.App.exe'
+                Assert 'Welcome exe baked into WIM' (Test-Path $welcomeExe)
+                $welcomeFlavours = Get-ChildItem (Join-Path $mount 'Program Files\SilverOS\Welcome\flavours') -Filter '*.json' -EA SilentlyContinue
+                Assert 'Welcome flavours baked (>=1 .json)' ($welcomeFlavours.Count -ge 1)
+            }
         } finally { Dismount-WindowsImage -Path $mount -Discard | Out-Null }
     }
 } finally { Dismount-DiskImage -ImagePath $IsoPath | Out-Null }