diff --git a/.github/workflows/unittests.yaml b/.github/workflows/unittests.yaml
index 68d0e563..b17cd74f 100644
--- a/.github/workflows/unittests.yaml
+++ b/.github/workflows/unittests.yaml
@@ -27,13 +27,16 @@ jobs:
     - name: Install Pester
       run: |
         Set-ExecutionPolicy -ExecutionPolicy Bypass -Scope Process
-        Install-Module -Name Pester -Force -SkipPublisherCheck -AllowClobber
+        Install-Module -Name Pester -RequiredVersion 5.8.0 -Force -SkipPublisherCheck -AllowClobber
+        Import-Module Pester -RequiredVersion 5.8.0 -Force
+        Get-Module Pester | Select-Object Name, Version, Path
       shell: pwsh
 
     - name: Run Pester tests
       run: |
         Set-ExecutionPolicy -ExecutionPolicy Bypass -Scope Process
-        Invoke-Pester -Path 'pester/*.Tests.ps1' -Output Detailed
+        Import-Module Pester -RequiredVersion 5.8.0 -Force
+        Invoke-Pester -Path 'pester/*.Tests.ps1' -Output Detailed -CI
 
       shell: pwsh
       env:
diff --git a/.gitignore b/.gitignore
index a97fe97d..038c7354 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@ Microsoft.PowerShell.ConsoleHost.dll
 winutil.exe.config
 winutil.ps1
 binary/
+testResults.xml
 
 # general software/os specific
 desktop.ini
diff --git a/AGENTS.md b/AGENTS.md
index 072010a5..e28a4498 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -44,6 +44,7 @@ WinUtil is a Windows PowerShell utility with a WPF interface. The repository is
   ```
 - Run tests:
   ```powershell
+  Import-Module Pester -RequiredVersion 5.8.0 -Force
   Invoke-Pester -Path 'pester/*.Tests.ps1' -Output Detailed
   ```
 - Run Script Analyzer with project settings when available:
@@ -182,4 +183,8 @@ Proceed without asking when:
 When the user corrects an agent approach, add or tighten one concrete rule here before ending the session. Keep this section short and prune rules that no longer matter.
 
 - Keep `winutil.ps1` generated-only: change source files, compile to verify, and never stage the generated script.
-
+- Keep WinUtil runtime logging in the existing timestamped `%LocalAppData%\winutil\logs\winutil_*.log` session file; do not create a separate root `winutil.log`.
+- Import Pester 5.8.0 before running tests so `Invoke-Pester -Output Detailed -CI` does not resolve to Windows' inbox Pester 3.4.0.
+- Keep package install/uninstall process launches simple unless explicitly requested; do not add a separate stdout/stderr process logging helper for winget or Chocolatey.
+- When the active log file is owned by `Start-Transcript`, do not call `Add-Content` against that file; write to host output so the transcript captures the line in the same log file without recording a terminating-error diagnostic.
+- Log install/uninstall package names and package-manager IDs before queuing background runspace work; do not rely on runspace host output for the package identity.
diff --git a/SPEC.md b/SPEC.md
index 780dc636..62e9225e 100644
--- a/SPEC.md
+++ b/SPEC.md
@@ -94,7 +94,8 @@ Expected validation for source changes:
 
 - `.\Compile.ps1` verifies the compiler can generate `winutil.ps1`.
 - `.\Compile.ps1 -Run` compiles and launches the generated utility for manual GUI verification.
-- `Invoke-Pester -Path 'pester/*.Tests.ps1' -Output Detailed` runs the Pester suite.
+- `Install-Module -Name Pester -RequiredVersion 5.8.0 -Scope CurrentUser -Force -SkipPublisherCheck` installs the supported Pester version.
+- `Import-Module Pester -RequiredVersion 5.8.0 -Force; Invoke-Pester -Path 'pester/*.Tests.ps1' -Output Detailed -CI` runs the Pester suite.
 - GitHub Actions also runs a compile check and PowerShell Script Analyzer with `lint/PSScriptAnalyser.ps1`.
 
 The generated `winutil.ps1` may appear locally after compile. It remains ignored build output and must not be committed.
@@ -102,4 +103,3 @@ The generated `winutil.ps1` may appear locally after compile. It remains ignored
 ## Release Artifact
 
 GitHub Actions is responsible for producing the release `winutil.ps1` from repository sources. A release should be considered valid only if the generated script came from the compile process, not from direct manual edits to `winutil.ps1`.
-
diff --git a/TEST_TODO.md b/TEST_TODO.md
new file mode 100644
index 00000000..d117d0b7
--- /dev/null
+++ b/TEST_TODO.md
@@ -0,0 +1,107 @@
+# Test TODO
+
+Current suite status: broad parser, import, config JSON, compile, and runspace smoke coverage exists, but runtime behavior coverage is still very thin. Work from the top down; the first items are the highest-value gaps.
+
+## P0 - Highest Priority
+
+- [x] Add config reference integrity tests.
+  - Verify every preset entry points to an existing tweak, feature, app, appx item, or supported action.
+  - Verify `appnavigation.json` entries point to real tabs/panels and valid config groups.
+  - Verify tweak, feature, DNS, appx, and theme entries include all fields used by the UI/rendering code.
+  - Verify all embedded script strings in `config/*.json` parse as PowerShell when wrapped as scriptblocks.
+
+- [x] Add XAML/control wiring tests.
+  - Load `xaml/inputXML.xaml` as XML and verify expected named controls exist.
+  - Verify controls referenced through `$sync["Name"]`, `$sync.Name`, or event handlers exist in XAML or are intentionally created dynamically.
+  - Verify `Invoke-WPF*` handler names used by buttons/tabs correspond to real functions.
+  - Verify core tabs, search controls, install panels, tweak panels, and Win11 Creator controls are present.
+
+- [x] Add mock-based tests for registry and service helpers.
+  - Cover `Set-WinUtilRegistry` set/remove paths with `Mock New-Item`, `Mock Set-ItemProperty`, and `Mock Remove-ItemProperty`.
+  - Cover `Set-WinUtilService` for missing services, startup type changes, and no-op behavior.
+  - Assert command parameters instead of touching the real registry or services.
+
+- [x] Add package selection and package manager tests.
+  - Cover `Get-WinUtilSelectedPackages` for winget-only, choco-only, mixed, `na`, empty, duplicate, and missing package entries.
+  - Cover `Test-WinUtilPackageManager` with mocked `Get-Command`.
+  - Cover `Install-WinUtilProgramWinget` and `Install-WinUtilProgramChoco` with mocked `Start-Process`, including install/uninstall arguments.
+
+- [x] Add runspace behavior tests beyond the smoke test.
+  - Cover no argument list, one named parameter, multiple named parameters, and scriptblock failures.
+  - Assert callers receive a single `IAsyncResult`.
+  - Verify failure output/errors can be retrieved by the owning PowerShell instance.
+  - Add focused tests for public functions that call `Invoke-WPFRunspace` without executing their destructive inner work.
+
+## P1 - Important Workflow Coverage
+
+- [x] Add tweak execution orchestration tests.
+  - Cover `Invoke-WinUtilTweaks` with mocked `Invoke-WinUtilScript`, `Set-WinUtilRegistry`, `Set-WinUtilService`, and `Set-WinUtilDNS`.
+  - Verify undo mode uses `OriginalValue` and `OriginalType`.
+  - Verify DNS provider and progress counters are passed through correctly.
+
+- [x] Add install/uninstall workflow tests.
+  - Cover `Invoke-WPFInstall` and `Invoke-WPFUnInstall` with mocked package sorting and mocked installers.
+  - Verify empty selection prompts and exits.
+  - Verify process-running guard prevents a second install/uninstall.
+  - Verify taskbar/progress cleanup happens on success and error.
+
+- [x] Add update profile tests.
+  - Cover `Invoke-WPFUpdatesdisable`, `Invoke-WPFUpdatesdefault`, and `Invoke-WPFUpdatessecurity` with mocks for registry, services, scheduled tasks, and process calls.
+  - Assert intended registry paths, values, service startup types, and scheduled task paths.
+  - Keep all tests non-mutating.
+
+- [x] Add AppX removal tests.
+  - Cover `Remove-WinUtilAPPX` with mocked `Get-AppxPackage` and `Remove-AppxPackage`.
+  - Cover `Invoke-WPFAppxRemoval` selection behavior and runspace parameter passing.
+  - Verify empty selection is handled without removal calls.
+
+- [x] Add UI selection/state helper tests.
+  - Cover `Update-WinUtilSelections`, `Reset-WPFCheckBoxes`, `Invoke-WPFSelectedCheckboxesUpdate`, and `Invoke-WPFToggleAllCategories`.
+  - Use small fake checkbox/control objects instead of WPF windows where possible.
+  - Verify selected apps, tweaks, toggles, appx, and features stay in sync with checkbox state.
+
+## P2 - Domain-Specific Coverage
+
+- [x] Expand Win11 Creator tests.
+  - Test edition name to edition ID mapping.
+  - Test `ei.cfg` and `PID.txt` generation/removal behavior in a temp directory.
+  - Test autounattend conversion preserves required nodes and removes unsupported product key paths.
+  - Test driver injection branching with mocked DISM commands.
+  - Test ISO export fallback when `oscdimg.exe` is missing and winget install fails.
+
+- [x] Add preferences/theme tests.
+  - Cover `Set-Preferences` loading, saving, old preference cleanup, and defaults.
+  - Cover theme resource updates without opening the full GUI.
+  - Verify theme config contains required brushes/colors used by the theme code.
+
+- [x] Add search/filter tests.
+  - Cover `Find-AppsByNameOrDescription` and `Find-TweaksByNameOrDescription` with fake UI item trees.
+  - Verify empty search restores visibility.
+  - Verify category labels and panels hide/show correctly.
+  - Verify description and display-name matches both work.
+
+- [x] Add compile contract tests.
+  - Verify compiled config key transformation for `applications.json` adds `WPFInstall` prefixes.
+  - Verify source ordering in `winutil.ps1`: start script, functions, configs, XAML, autounattend XML, main script.
+  - Verify generated build date placeholder is replaced.
+  - Verify generated script does not contain unresolved `#{replaceme}`.
+
+## P3 - Nice To Have
+
+- [ ] Add Script Analyzer as a failing CI gate once existing findings are triaged.
+- [ ] Add docs generation/link checks for `docs/content`.
+- [ ] Add coverage reporting in CI as informational output.
+- [ ] Add a lightweight test helper module for fake `$sync`, fake WPF controls, and common mocks.
+- [ ] Add regression tests whenever a production bug is fixed.
+
+## Guardrails
+
+- Tests must not mutate the real registry, services, scheduled tasks, package managers, AppX packages, USB disks, ISOs, or user profile state.
+- Prefer Pester mocks and temp directories for system-facing code.
+- Keep generated `winutil.ps1` ignored and never commit it.
+- Run the full gate before marking test work complete:
+
+```powershell
+Import-Module Pester -RequiredVersion 5.8.0 -Force
+Invoke-Pester -Path 'pester/*.Tests.ps1' -Output Detailed -CI
+```
diff --git a/docs/content/dev/architecture.md b/docs/content/dev/architecture.md
index 11ca1e4d..490b64a7 100644
--- a/docs/content/dev/architecture.md
+++ b/docs/content/dev/architecture.md
@@ -578,7 +578,9 @@ Tests are in `/pester/`:
 
 Run tests:
 ```powershell
-Invoke-Pester
+Install-Module -Name Pester -RequiredVersion 5.8.0 -Scope CurrentUser -Force -SkipPublisherCheck
+Import-Module Pester -RequiredVersion 5.8.0 -Force
+Invoke-Pester -Path 'pester/*.Tests.ps1' -Output Detailed -CI
 ```
 
 ## Build Process
diff --git a/functions/private/Get-WinUtilPackageLogSummary.ps1 b/functions/private/Get-WinUtilPackageLogSummary.ps1
new file mode 100644
index 00000000..b588c22d
--- /dev/null
+++ b/functions/private/Get-WinUtilPackageLogSummary.ps1
@@ -0,0 +1,28 @@
+function Get-WinUtilPackageLogSummary {
+    param(
+        [Parameter(Mandatory = $true)]
+        [object[]]$Packages,
+
+        [Parameter(Mandatory = $true)]
+        [PackageManagers]$Preference
+    )
+
+    @($Packages | ForEach-Object {
+        $package = $_
+        $packageName = @($package.Name, $package.Description, $package.winget, $package.choco) |
+            Where-Object { -not [string]::IsNullOrWhiteSpace([string]$_) -and $_ -ne "na" } |
+            Select-Object -First 1
+
+        if ([string]::IsNullOrWhiteSpace([string]$packageName)) {
+            $packageName = "Unknown package"
+        }
+
+        if ($Preference -eq [PackageManagers]::Choco -and -not [string]::IsNullOrWhiteSpace([string]$package.choco) -and $package.choco -ne "na") {
+            "$packageName (choco: $($package.choco))"
+        } elseif (-not [string]::IsNullOrWhiteSpace([string]$package.winget) -and $package.winget -ne "na") {
+            "$packageName (winget: $($package.winget))"
+        } else {
+            "$packageName (no package id)"
+        }
+    })
+}
diff --git a/functions/private/Get-WinUtilSelectedPackages.ps1 b/functions/private/Get-WinUtilSelectedPackages.ps1
index dc67c0c7..dae05524 100644
--- a/functions/private/Get-WinUtilSelectedPackages.ps1
+++ b/functions/private/Get-WinUtilSelectedPackages.ps1
@@ -21,17 +21,32 @@ function Get-WinUtilSelectedPackages {
     $packages[[PackageManagers]::Winget] = $packagesWinget
     $packages[[PackageManagers]::Choco] = $packagesChoco
 
+    function Add-PackageId {
+        param(
+            [System.Collections.ArrayList]$Target,
+            $PackageId
+        )
+
+        if ([string]::IsNullOrWhiteSpace([string]$PackageId) -or $PackageId -eq "na") {
+            return
+        }
+
+        if (-not $Target.Contains($PackageId)) {
+            $null = $Target.Add($PackageId)
+        }
+    }
+
     foreach ($package in $PackageList) {
         switch ($Preference) {
             "Choco" {
-                if ($package.choco -eq "na") {
-                    $null = $packagesWinget.add($package.winget)
+                if ([string]::IsNullOrWhiteSpace([string]$package.choco) -or $package.choco -eq "na") {
+                    Add-PackageId -Target $packagesWinget -PackageId $package.winget
                 } else {
-                    $null = $packagesChoco.add($package.choco)
+                    Add-PackageId -Target $packagesChoco -PackageId $package.choco
                 }
             }
             "Winget" {
-                $null = $packagesWinget.add($package.winget)
+                Add-PackageId -Target $packagesWinget -PackageId $package.winget
             }
         }
     }
diff --git a/functions/private/Install-WinUtilProgramChoco.ps1 b/functions/private/Install-WinUtilProgramChoco.ps1
index 4c673cdd..9d9853e5 100644
--- a/functions/private/Install-WinUtilProgramChoco.ps1
+++ b/functions/private/Install-WinUtilProgramChoco.ps1
@@ -9,8 +9,12 @@ function Install-WinUtilProgramChoco {
     )
 
     if ($Action -eq 'Install') {
-        Start-Process -FilePath choco -ArgumentList "install $Programs -y" -NoNewWindow -Wait
+        $arguments = "install $Programs -y"
     } else {
-        Start-Process -FilePath choco -ArgumentList "uninstall $Programs -y" -NoNewWindow -Wait
+        $arguments = "uninstall $Programs -y"
     }
+
+    Write-WinUtilLog -Component "Package" -Message "$Action choco package(s): $($Programs -join ', ')"
+    $process = Start-Process -FilePath choco -ArgumentList $arguments -NoNewWindow -Wait -PassThru
+    Write-WinUtilLog -Component "Package" -Message "$Action choco package(s) completed: $($Programs -join ', ') (exit code: $($process.ExitCode))"
 }
diff --git a/functions/private/Install-WinUtilProgramWinget.ps1 b/functions/private/Install-WinUtilProgramWinget.ps1
index 3ab8ef54..d4b6f1f4 100644
--- a/functions/private/Install-WinUtilProgramWinget.ps1
+++ b/functions/private/Install-WinUtilProgramWinget.ps1
@@ -20,9 +20,13 @@ Function Install-WinUtilProgramWinget {
         }
 
         if ($Action -eq 'Install') {
-            Start-Process -FilePath winget -ArgumentList @("install", "--id", $program, "--accept-package-agreements", "--accept-source-agreements", "--source", $source, "--silent") -NoNewWindow -Wait
+            $arguments = @("install", "--id", $program, "--accept-package-agreements", "--accept-source-agreements", "--source", $source, "--silent")
         } else {
-            Start-Process -FilePath winget -ArgumentList @("uninstall", "--id", $program, "--source", $source, "--silent") -NoNewWindow -Wait
+            $arguments = @("uninstall", "--id", $program, "--source", $source, "--silent")
         }
+
+        Write-WinUtilLog -Component "Package" -Message "$Action winget package: $program (source: $source)"
+        $process = Start-Process -FilePath winget -ArgumentList $arguments -NoNewWindow -Wait -PassThru
+        Write-WinUtilLog -Component "Package" -Message "$Action winget package completed: $program (exit code: $($process.ExitCode))"
     }
 }
diff --git a/functions/private/Invoke-WinUtilFeatureInstall.ps1 b/functions/private/Invoke-WinUtilFeatureInstall.ps1
index 1017223f..560bde65 100644
--- a/functions/private/Invoke-WinUtilFeatureInstall.ps1
+++ b/functions/private/Invoke-WinUtilFeatureInstall.ps1
@@ -1,16 +1,22 @@
 function Invoke-WinUtilFeatureInstall ($CheckBox) {
+    Write-WinUtilLog -Component "Feature" -Message "Applying feature action: $CheckBox"
 
     if ($sync.configs.feature.$CheckBox.feature) {
         foreach ($feature in $sync.configs.feature.$CheckBox.feature) {
             Write-Host "Installing $feature"
+            Write-WinUtilLog -Component "Feature" -Message "Enabling Windows optional feature: $feature"
             Enable-WindowsOptionalFeature -Online -FeatureName $feature -All -NoRestart -ErrorAction Stop
+            Write-WinUtilLog -Component "Feature" -Message "Enabled Windows optional feature: $feature"
         }
     }
 
     if ($sync.configs.feature.$CheckBox.InvokeScript) {
         foreach ($script in $sync.configs.feature.$CheckBox.InvokeScript) {
             Write-Host "Running Script for $CheckBox"
+            Write-WinUtilLog -Component "Feature" -Message "Running feature script for: $CheckBox"
             Invoke-Command -ScriptBlock ([scriptblock]::Create($script)) -ErrorAction Stop
+            Write-WinUtilLog -Component "Feature" -Message "Completed feature script for: $CheckBox"
         }
     }
+    Write-WinUtilLog -Component "Feature" -Message "Feature action completed: $CheckBox"
 }
diff --git a/functions/private/Invoke-WinUtilScript.ps1 b/functions/private/Invoke-WinUtilScript.ps1
index d49b9f46..59a98541 100644
--- a/functions/private/Invoke-WinUtilScript.ps1
+++ b/functions/private/Invoke-WinUtilScript.ps1
@@ -22,23 +22,30 @@ function Invoke-WinUtilScript {
 
     try {
         Write-Host "Running Script for $Name"
+        Write-WinUtilLog -Component "Script" -Message "Running script for $Name"
         Invoke-Command $scriptblock -ErrorAction Stop
+        Write-WinUtilLog -Component "Script" -Message "Completed script for $Name"
     } catch [System.Management.Automation.CommandNotFoundException] {
         Write-Warning "The specified command was not found."
         Write-Warning $PSItem.Exception.message
+        Write-WinUtilLog -Level "ERROR" -Component "Script" -Message "Command not found while running script for $Name`: $($PSItem.Exception.Message)"
     } catch [System.Management.Automation.RuntimeException] {
         Write-Warning "A runtime exception occurred."
         Write-Warning $PSItem.Exception.message
+        Write-WinUtilLog -Level "ERROR" -Component "Script" -Message "Runtime exception while running script for $Name`: $($PSItem.Exception.Message)"
     } catch [System.Security.SecurityException] {
         Write-Warning "A security exception occurred."
         Write-Warning $PSItem.Exception.message
+        Write-WinUtilLog -Level "ERROR" -Component "Script" -Message "Security exception while running script for $Name`: $($PSItem.Exception.Message)"
     } catch [System.UnauthorizedAccessException] {
         Write-Warning "Access denied. You do not have permission to perform this operation."
         Write-Warning $PSItem.Exception.message
+        Write-WinUtilLog -Level "ERROR" -Component "Script" -Message "Access denied while running script for $Name`: $($PSItem.Exception.Message)"
     } catch {
         # Generic catch block to handle any other type of exception
         Write-Warning "Unable to run script for $Name due to unhandled exception."
         Write-Warning $psitem.Exception.StackTrace
+        Write-WinUtilLog -Level "ERROR" -Component "Script" -Message "Unhandled exception while running script for $Name`: $($psitem.Exception.Message)"
     }
 
 }
diff --git a/functions/private/Invoke-WinUtilTweaks.ps1 b/functions/private/Invoke-WinUtilTweaks.ps1
index f3812c88..2576f7f9 100644
--- a/functions/private/Invoke-WinUtilTweaks.ps1
+++ b/functions/private/Invoke-WinUtilTweaks.ps1
@@ -21,6 +21,9 @@ function Invoke-WinUtilTweaks {
         $KeepServiceStartup = $true
     )
 
+    $action = if ($undo) { "Undo" } else { "Apply" }
+    Write-WinUtilLog -Component "Tweaks" -Message "$action tweak: $CheckBox"
+
     if ($undo) {
         $Values = @{
             Registry = "OriginalValue"
@@ -77,4 +80,5 @@ function Invoke-WinUtilTweaks {
             }
         }
     }
+    Write-WinUtilLog -Component "Tweaks" -Message "$action tweak completed: $CheckBox"
 }
diff --git a/functions/private/Remove-WinUtilAPPX.ps1 b/functions/private/Remove-WinUtilAPPX.ps1
index 12c0ed42..38759157 100644
--- a/functions/private/Remove-WinUtilAPPX.ps1
+++ b/functions/private/Remove-WinUtilAPPX.ps1
@@ -16,6 +16,8 @@ function Remove-WinUtilAPPX {
     )
 
     Write-Host "Removing $Name"
+    Write-WinUtilLog -Component "AppX" -Message "Removing AppX package pattern: $Name"
     Get-AppxPackage $Name -AllUsers | Remove-AppxPackage -AllUsers
     Get-AppxProvisionedPackage -Online | Where-Object DisplayName -like $Name | Remove-AppxProvisionedPackage -Online
+    Write-WinUtilLog -Component "AppX" -Message "AppX removal completed for package pattern: $Name"
 }
diff --git a/functions/private/Set-WinUtilDNS.ps1 b/functions/private/Set-WinUtilDNS.ps1
index 04be90be..f96a5682 100644
--- a/functions/private/Set-WinUtilDNS.ps1
+++ b/functions/private/Set-WinUtilDNS.ps1
@@ -12,22 +12,31 @@ function Set-WinUtilDNS {
 
     #>
     param($DNSProvider)
-    if($DNSProvider -eq "Default") {return}
+    if($DNSProvider -eq "Default") {
+        Write-WinUtilLog -Component "DNS" -Message "DNS provider is Default; no DNS changes applied."
+        return
+    }
     try {
         $Adapters = Get-NetAdapter | Where-Object {$_.Status -eq "Up"}
         Write-Host "Ensuring DNS is set to $DNSProvider on the following interfaces:"
         Write-Host $($Adapters | Out-String)
+        Write-WinUtilLog -Component "DNS" -Message "Setting DNS provider to $DNSProvider for $(@($Adapters).Count) active adapter(s)."
 
         Foreach ($Adapter in $Adapters) {
             if($DNSProvider -eq "DHCP") {
+                Write-WinUtilLog -Component "DNS" -Message "Resetting DNS to DHCP on adapter $($Adapter.Name) (ifIndex: $($Adapter.ifIndex))."
                 Set-DnsClientServerAddress -InterfaceIndex $Adapter.ifIndex -ResetServerAddresses
             } else {
+                Write-WinUtilLog -Component "DNS" -Message "Setting IPv4 DNS on adapter $($Adapter.Name) (ifIndex: $($Adapter.ifIndex)) to $($sync.configs.dns.$DNSProvider.Primary), $($sync.configs.dns.$DNSProvider.Secondary)."
                 Set-DnsClientServerAddress -InterfaceIndex $Adapter.ifIndex -ServerAddresses ("$($sync.configs.dns.$DNSProvider.Primary)", "$($sync.configs.dns.$DNSProvider.Secondary)")
+                Write-WinUtilLog -Component "DNS" -Message "Setting IPv6 DNS on adapter $($Adapter.Name) (ifIndex: $($Adapter.ifIndex)) to $($sync.configs.dns.$DNSProvider.Primary6), $($sync.configs.dns.$DNSProvider.Secondary6)."
                 Set-DnsClientServerAddress -InterfaceIndex $Adapter.ifIndex -ServerAddresses ("$($sync.configs.dns.$DNSProvider.Primary6)", "$($sync.configs.dns.$DNSProvider.Secondary6)")
             }
         }
+        Write-WinUtilLog -Component "DNS" -Message "DNS provider change completed: $DNSProvider"
     } catch {
         Write-Warning "Unable to set DNS Provider due to an unhandled exception."
         Write-Warning $psitem.Exception.StackTrace
+        Write-WinUtilLog -Level "ERROR" -Component "DNS" -Message "Unable to set DNS provider $DNSProvider`: $($psitem.Exception.Message)"
     }
 }
diff --git a/functions/private/Set-WinUtilRegistry.ps1 b/functions/private/Set-WinUtilRegistry.ps1
index 3eacaf45..b15b3e59 100644
--- a/functions/private/Set-WinUtilRegistry.ps1
+++ b/functions/private/Set-WinUtilRegistry.ps1
@@ -32,25 +32,32 @@ function Set-WinUtilRegistry {
 
         If (!(Test-Path $Path)) {
             Write-Host "$Path was not found. Creating..."
+            Write-WinUtilLog -Component "Registry" -Message "Creating registry path: $Path"
             New-Item -Path $Path -Force -ErrorAction Stop | Out-Null
         }
 
         if ($Value -ne "<RemoveEntry>") {
             Write-Host "Set $Path\$Name to $Value"
+            Write-WinUtilLog -Component "Registry" -Message "Setting $Path\$Name ($Type) to $Value"
             Set-ItemProperty -Path $Path -Name $Name -Type $Type -Value $Value -Force -ErrorAction Stop | Out-Null
         }
         else{
             Write-Host "Remove $Path\$Name"
+            Write-WinUtilLog -Component "Registry" -Message "Removing $Path\$Name"
             Remove-ItemProperty -Path $Path -Name $Name -Force -ErrorAction Stop | Out-Null
         }
     } catch [System.Security.SecurityException] {
         Write-Warning "Unable to set $Path\$Name to $Value due to a Security Exception."
+        Write-WinUtilLog -Level "ERROR" -Component "Registry" -Message "Security exception while changing $Path\$Name to $Value`: $($psitem.Exception.Message)"
     } catch [System.Management.Automation.ItemNotFoundException] {
         Write-Warning $psitem.Exception.ErrorRecord
+        Write-WinUtilLog -Level "ERROR" -Component "Registry" -Message "Registry item not found while changing $Path\$Name`: $($psitem.Exception.Message)"
     } catch [System.UnauthorizedAccessException] {
        Write-Warning $psitem.Exception.Message
+       Write-WinUtilLog -Level "ERROR" -Component "Registry" -Message "Unauthorized while changing $Path\$Name`: $($psitem.Exception.Message)"
     } catch {
         Write-Warning "Unable to set $Name due to unhandled exception."
         Write-Warning $psitem.Exception.StackTrace
+        Write-WinUtilLog -Level "ERROR" -Component "Registry" -Message "Unhandled exception while changing $Path\$Name`: $($psitem.Exception.Message)"
     }
 }
diff --git a/functions/private/Set-WinUtilService.ps1 b/functions/private/Set-WinUtilService.ps1
index 3ef8bd06..8be5525e 100644
--- a/functions/private/Set-WinUtilService.ps1
+++ b/functions/private/Set-WinUtilService.ps1
@@ -20,21 +20,33 @@ Function Set-WinUtilService {
     )
     try {
         Write-Host "Setting Service $Name to $StartupType"
+        Write-WinUtilLog -Component "Service" -Message "Setting service $Name startup type to $StartupType"
 
         # Check if the service exists
         $service = Get-Service -Name $Name -ErrorAction Stop
 
+        if (($service.PSObject.Properties.Name -contains "StartType") -and ([string]$service.StartType -eq [string]$StartupType) ) {
+            Write-Host "Service $Name is already set to $StartupType"
+            Write-WinUtilLog -Component "Service" -Message "Service $Name startup type is already $StartupType; no change needed."
+            return
+        }
+
         # Service exists, proceed with changing properties -- while handling auto delayed start for PWSH 5
         if (($PSVersionTable.PSVersion.Major -lt 7) -and ($StartupType -eq "AutomaticDelayedStart")) {
             sc.exe config $Name start=delayed-auto
         } else {
             $service | Set-Service -StartupType $StartupType -ErrorAction Stop
         }
-    } catch [System.ServiceProcess.ServiceNotFoundException] {
-        Write-Warning "Service $Name was not found."
+        Write-WinUtilLog -Component "Service" -Message "Service $Name startup type set to $StartupType"
     } catch {
-        Write-Warning "Unable to set $Name due to unhandled exception."
-        Write-Warning $_.Exception.Message
+        if ($_.FullyQualifiedErrorId -like "NoServiceFoundForGivenName,*") {
+            Write-Warning "Service $Name was not found."
+            Write-WinUtilLog -Level "WARN" -Component "Service" -Message "Service $Name was not found."
+        } else {
+            Write-Warning "Unable to set $Name due to unhandled exception."
+            Write-Warning $_.Exception.Message
+            Write-WinUtilLog -Level "ERROR" -Component "Service" -Message "Unable to set service $Name to $StartupType`: $($_.Exception.Message)"
+        }
     }
 
 }
diff --git a/functions/private/Show-WinUtilMessage.ps1 b/functions/private/Show-WinUtilMessage.ps1
new file mode 100644
index 00000000..f52256ab
--- /dev/null
+++ b/functions/private/Show-WinUtilMessage.ps1
@@ -0,0 +1,14 @@
+function Show-WinUtilMessage {
+    <#
+    .SYNOPSIS
+        Shows a WinUtil message box and returns the selected result.
+    #>
+    param (
+        [string]$Message,
+        [string]$Title = "Winutil",
+        $Button = "OK",
+        $Icon = "Information"
+    )
+
+    [System.Windows.MessageBox]::Show($Message, $Title, $Button, $Icon)
+}
diff --git a/functions/private/Write-WinUtilLog.ps1 b/functions/private/Write-WinUtilLog.ps1
new file mode 100644
index 00000000..da9e13ab
--- /dev/null
+++ b/functions/private/Write-WinUtilLog.ps1
@@ -0,0 +1,81 @@
+function Write-WinUtilLog {
+    <#
+
+    .SYNOPSIS
+        Writes a timestamped WinUtil log entry to the active session log.
+
+    .PARAMETER Message
+        The message to write.
+
+    .PARAMETER Level
+        The severity level for the log entry.
+
+    .PARAMETER Component
+        The WinUtil component producing the log entry.
+
+    #>
+    param (
+        [Parameter(Mandatory = $true)]
+        [string]$Message,
+
+        [ValidateSet("INFO", "WARN", "ERROR", "DEBUG")]
+        [string]$Level = "INFO",
+
+        [string]$Component = "WinUtil"
+    )
+
+    try {
+        $logPath = $null
+        $transcriptPath = $null
+        if ($null -ne $sync -and $sync.ContainsKey("logPath")) {
+            $logPath = $sync.logPath
+        }
+
+        if ($null -ne $sync -and $sync.ContainsKey("transcriptPath")) {
+            $transcriptPath = $sync.transcriptPath
+        }
+
+        if ([string]::IsNullOrWhiteSpace($logPath) -and -not [string]::IsNullOrWhiteSpace($transcriptPath)) {
+            $logPath = $transcriptPath
+        }
+
+        if ([string]::IsNullOrWhiteSpace($logPath) -and $null -ne $sync -and $sync.ContainsKey("winutildir")) {
+            $logDirectory = Join-Path $sync.winutildir "logs"
+            $logPath = Join-Path $logDirectory "winutil_$(Get-Date -Format "yyyy-MM-dd_HH-mm-ss").log"
+            $sync.logPath = $logPath
+        }
+
+        if ([string]::IsNullOrWhiteSpace($logPath) -and -not [string]::IsNullOrWhiteSpace($env:LocalAppData)) {
+            if ([string]::IsNullOrWhiteSpace($script:WinUtilLogPath)) {
+                $logDirectory = Join-Path (Join-Path $env:LocalAppData "winutil") "logs"
+                $script:WinUtilLogPath = Join-Path $logDirectory "winutil_$(Get-Date -Format "yyyy-MM-dd_HH-mm-ss").log"
+            }
+            $logPath = $script:WinUtilLogPath
+        }
+
+        if ([string]::IsNullOrWhiteSpace($logPath)) {
+            return
+        }
+
+        $logDirectory = Split-Path -Path $logPath -Parent
+        if (-not (Test-Path $logDirectory)) {
+            New-Item -Path $logDirectory -ItemType Directory -Force | Out-Null
+        }
+
+        $timestamp = Get-Date -Format "yyyy-MM-dd HH:mm:ss.fff"
+        $line = "[$timestamp] [$Level] [$Component] $Message"
+
+        if (-not [string]::IsNullOrWhiteSpace($transcriptPath) -and $logPath -eq $transcriptPath) {
+            Write-Host $line
+            return
+        }
+
+        try {
+            Add-Content -Path $logPath -Value $line -Encoding UTF8 -ErrorAction Stop
+        } catch [System.IO.IOException] {
+            Write-Host $line
+        }
+    } catch {
+        Write-Warning "Unable to write WinUtil log entry: $($_.Exception.Message)"
+    }
+}
diff --git a/functions/public/Invoke-WPFAppxRemoval.ps1 b/functions/public/Invoke-WPFAppxRemoval.ps1
index d192c375..074a30df 100644
--- a/functions/public/Invoke-WPFAppxRemoval.ps1
+++ b/functions/public/Invoke-WPFAppxRemoval.ps1
@@ -1,6 +1,6 @@
 function Invoke-WPFAppxRemoval {
-    if (-not ($sync.selectedAppx)) {
-        [System.Windows.Forms.MessageBox]::Show("No AppX Package selected","Error","OK","Error")
+    if ($null -eq $sync.selectedAppx -or $sync.selectedAppx.Count -eq 0) {
+        Show-WinUtilMessage -Message "No AppX Package selected" -Title "Error" -Button "OK" -Icon "Error"
         return
     }
 
@@ -11,26 +11,32 @@ function Invoke-WPFAppxRemoval {
         param($selected, $apps)
 
         $sync.ProcessRunning = $true
+        Write-WinUtilLog -Component "AppX" -Message "Starting AppX removal for $(@($selected).Count) selected package(s)."
 
         foreach ($key in $selected) {
             if ($key -eq "WPFAppxMicrosoft_XboxGamingOverlay") {
                 # Making sure Game Bar isn't running
+                Write-WinUtilLog -Component "AppX" -Message "Stopping GameBarFTServer before removing Xbox Gaming Overlay."
                 Stop-Process -Name GameBarFTServer
 
                 # This stops annoying ms-gamebar popup when launching games.
+                Write-WinUtilLog -Component "AppX" -Message "Disabling Game DVR capture before removing Xbox Gaming Overlay."
                 Set-ItemProperty -Path HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\GameDVR -Name AppCaptureEnabled -Value 0
             }
 
             if ($key -eq "WPFAppxMicrosoft_WindowsNotepad") {
                 # i hope your having fun reading this
+                Write-WinUtilLog -Component "AppX" -Message "Stopping dllhost before removing Notepad."
                 Stop-Process -Name dllhost
             }
 
             Write-Host "Removing $($apps[$key].Content)"
+            Write-WinUtilLog -Component "AppX" -Message "Removing $($apps[$key].Content) ($($apps[$key].PackageId))."
             Get-AppxPackage -Name $apps[$key].PackageId -AllUsers | Remove-AppxPackage -AllUsers
 
             if ($key -eq "WPFAppxMSTeams") {
                 # Uninstalls Microsoft Teams Meeting Add-in for Microsoft Office
+                Write-WinUtilLog -Component "AppX" -Message "Uninstalling Microsoft Teams meeting add-in package."
                 Get-Package -Name "Microsoft Teams*" -ErrorAction SilentlyContinue | Uninstall-Package -Force
             }
         }
@@ -38,6 +44,7 @@ function Invoke-WPFAppxRemoval {
         Write-Host "================================="
         Write-Host "--   AppX Removal Finished   ---"
         Write-Host "================================="
+        Write-WinUtilLog -Component "AppX" -Message "AppX removal finished."
 
         $sync.ProcessRunning = $false
     }
diff --git a/functions/public/Invoke-WPFInstall.ps1 b/functions/public/Invoke-WPFInstall.ps1
index 3d052e31..d7a70cb2 100644
--- a/functions/public/Invoke-WPFInstall.ps1
+++ b/functions/public/Invoke-WPFInstall.ps1
@@ -9,17 +9,20 @@ function Invoke-WPFInstall {
 
     if($sync.ProcessRunning) {
         $msg = "[Invoke-WPFInstall] An Install process is currently running."
-        [System.Windows.MessageBox]::Show($msg, "Winutil", [System.Windows.MessageBoxButton]::OK, [System.Windows.MessageBoxImage]::Warning)
+        Show-WinUtilMessage -Message $msg -Title "Winutil" -Button "OK" -Icon "Warning"
         return
     }
 
     if ($PackagesToInstall.Count -eq 0) {
         $WarningMsg = "Please select the program(s) to install or upgrade."
-        [System.Windows.MessageBox]::Show($WarningMsg, $AppTitle, [System.Windows.MessageBoxButton]::OK, [System.Windows.MessageBoxImage]::Warning)
+        Show-WinUtilMessage -Message $WarningMsg -Title $AppTitle -Button "OK" -Icon "Warning"
         return
     }
 
     $ManagerPreference = $sync.preferences.packagemanager
+    Write-WinUtilLog -Component "Install" -Message "Install requested for $(@($PackagesToInstall).Count) selected package(s) using preference: $ManagerPreference"
+    $packageSummary = Get-WinUtilPackageLogSummary -Packages $PackagesToInstall -Preference $ManagerPreference
+    Write-WinUtilLog -Component "Install" -Message "Install selected package(s): $($packageSummary -join '; ')"
 
     $handle = Invoke-WPFRunspace -ParameterList @(("PackagesToInstall", $PackagesToInstall),("ManagerPreference", $ManagerPreference)) -ScriptBlock {
         param($PackagesToInstall, $ManagerPreference)
@@ -28,6 +31,7 @@ function Invoke-WPFInstall {
 
         $packagesWinget = $packagesSorted[[PackageManagers]::Winget]
         $packagesChoco = $packagesSorted[[PackageManagers]::Choco]
+        Write-WinUtilLog -Component "Install" -Message "Install package manager split: winget=$(@($packagesWinget).Count), choco=$(@($packagesChoco).Count)"
 
         try {
             $sync.ProcessRunning = $true
@@ -44,13 +48,17 @@ function Invoke-WPFInstall {
             Write-Host "==========================================="
             Write-Host "--      Installs have finished          ---"
             Write-Host "==========================================="
+            Write-WinUtilLog -Component "Install" -Message "Install workflow completed."
             Invoke-WPFUIThread -ScriptBlock { Set-WinUtilTaskbaritem -state "None" -overlay "checkmark" }
         } catch {
+            Hide-WPFInstallAppBusy
             Write-Host "==========================================="
             Write-Host "Error: $_"
             Write-Host "==========================================="
+            Write-WinUtilLog -Level "ERROR" -Component "Install" -Message "Install workflow failed: $($_.Exception.Message)"
             Invoke-WPFUIThread -ScriptBlock { Set-WinUtilTaskbaritem -state "Error" -overlay "warning" }
+        } finally {
+            $sync.ProcessRunning = $False
         }
-        $sync.ProcessRunning = $False
     }
 }
diff --git a/functions/public/Invoke-WPFRunspace.ps1 b/functions/public/Invoke-WPFRunspace.ps1
index bccdd5df..03e05038 100644
--- a/functions/public/Invoke-WPFRunspace.ps1
+++ b/functions/public/Invoke-WPFRunspace.ps1
@@ -34,11 +34,11 @@ function Invoke-WPFRunspace {
     $script:powershell = [powershell]::Create()
 
     # Add Scriptblock and Arguments to runspace
-    $script:powershell.AddScript($ScriptBlock)
-    $script:powershell.AddArgument($ArgumentList)
+    [void]$script:powershell.AddScript($ScriptBlock)
+    [void]$script:powershell.AddArgument($ArgumentList)
 
     foreach ($parameter in $ParameterList) {
-        $script:powershell.AddParameter($parameter[0], $parameter[1])
+        [void]$script:powershell.AddParameter($parameter[0], $parameter[1])
     }
 
     $script:powershell.RunspacePool = $sync.runspace
diff --git a/functions/public/Invoke-WPFUnInstall.ps1 b/functions/public/Invoke-WPFUnInstall.ps1
index 4df18cb0..25ba23e7 100644
--- a/functions/public/Invoke-WPFUnInstall.ps1
+++ b/functions/public/Invoke-WPFUnInstall.ps1
@@ -11,26 +11,29 @@ function Invoke-WPFUnInstall {
 
     if($sync.ProcessRunning) {
         $msg = "[Invoke-WPFUnInstall] Install process is currently running"
-        [System.Windows.MessageBox]::Show($msg, "Winutil", [System.Windows.MessageBoxButton]::OK, [System.Windows.MessageBoxImage]::Warning)
+        Show-WinUtilMessage -Message $msg -Title "Winutil" -Button "OK" -Icon "Warning"
         return
     }
 
     if ($PackagesToUninstall.Count -eq 0) {
         $WarningMsg = "Please select the program(s) to uninstall"
-        [System.Windows.MessageBox]::Show($WarningMsg, $AppTitle, [System.Windows.MessageBoxButton]::OK, [System.Windows.MessageBoxImage]::Warning)
+        Show-WinUtilMessage -Message $WarningMsg -Title $AppTitle -Button "OK" -Icon "Warning"
         return
     }
 
-    $ButtonType = [System.Windows.MessageBoxButton]::YesNo
+    $ButtonType = "YesNo"
     $MessageboxTitle = "Are you sure?"
     $Messageboxbody = ("This will uninstall the following applications: `n $($PackagesToUninstall | Select-Object Name, Description| Out-String)")
-    $MessageIcon = [System.Windows.MessageBoxImage]::Information
+    $MessageIcon = "Information"
 
-    $confirm = [System.Windows.MessageBox]::Show($Messageboxbody, $MessageboxTitle, $ButtonType, $MessageIcon)
+    $confirm = Show-WinUtilMessage -Message $Messageboxbody -Title $MessageboxTitle -Button $ButtonType -Icon $MessageIcon
 
     if($confirm -eq "No") {return}
 
     $ManagerPreference = $sync.preferences.packagemanager
+    Write-WinUtilLog -Component "Uninstall" -Message "Uninstall requested for $(@($PackagesToUninstall).Count) selected package(s) using preference: $ManagerPreference"
+    $packageSummary = Get-WinUtilPackageLogSummary -Packages $PackagesToUninstall -Preference $ManagerPreference
+    Write-WinUtilLog -Component "Uninstall" -Message "Uninstall selected package(s): $($packageSummary -join '; ')"
 
     Invoke-WPFRunspace -ParameterList @(("PackagesToUninstall", $PackagesToUninstall),("ManagerPreference", $ManagerPreference)) -ScriptBlock {
         param($PackagesToUninstall, $ManagerPreference)
@@ -38,6 +41,7 @@ function Invoke-WPFUnInstall {
         $packagesSorted = Get-WinUtilSelectedPackages -PackageList $PackagesToUninstall -Preference $ManagerPreference
         $packagesWinget = $packagesSorted[[PackageManagers]::Winget]
         $packagesChoco = $packagesSorted[[PackageManagers]::Choco]
+        Write-WinUtilLog -Component "Uninstall" -Message "Uninstall package manager split: winget=$(@($packagesWinget).Count), choco=$(@($packagesChoco).Count)"
 
         try {
             $sync.ProcessRunning = $true
@@ -58,14 +62,18 @@ function Invoke-WPFUnInstall {
             Write-Host "==========================================="
             Write-Host "--       Uninstalls have finished       ---"
             Write-Host "==========================================="
+            Write-WinUtilLog -Component "Uninstall" -Message "Uninstall workflow completed."
             Invoke-WPFUIThread -ScriptBlock { Set-WinUtilTaskbaritem -state "None" -overlay "checkmark" }
         } catch {
+            Hide-WPFInstallAppBusy
             Write-Host "==========================================="
             Write-Host "Error: $_"
             Write-Host "==========================================="
+            Write-WinUtilLog -Level "ERROR" -Component "Uninstall" -Message "Uninstall workflow failed: $($_.Exception.Message)"
            Invoke-WPFUIThread -ScriptBlock { Set-WinUtilTaskbaritem -state "Error" -overlay "warning" }
+        } finally {
+            $sync.ProcessRunning = $False
         }
-        $sync.ProcessRunning = $False
 
     }
 }
diff --git a/functions/public/Invoke-WPFUpdatesdefault.ps1 b/functions/public/Invoke-WPFUpdatesdefault.ps1
index 7e280c32..dcd88982 100644
--- a/functions/public/Invoke-WPFUpdatesdefault.ps1
+++ b/functions/public/Invoke-WPFUpdatesdefault.ps1
@@ -6,8 +6,10 @@ function Invoke-WPFUpdatesdefault {
 
     #>
     $ErrorActionPreference = 'SilentlyContinue'
+    Write-WinUtilLog -Component "Updates" -Message "Resetting Windows Update settings to default."
 
     Write-Host "Removing Windows Update policy settings..." -ForegroundColor Green
+    Write-WinUtilLog -Component "Updates" -Message "Removing Windows Update policy registry paths."
 
     Remove-Item -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Recurse -Force
     Remove-Item -Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\DeliveryOptimization" -Recurse -Force
@@ -17,24 +19,31 @@ function Invoke-WPFUpdatesdefault {
     Remove-Item -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" -Recurse -Force
 
     Write-Host "Showing Windows Updates in settings..."
+    Write-WinUtilLog -Component "Updates" -Message "Showing Windows Update settings page."
     Remove-ItemProperty -Path HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer -Name SettingsPageVisibility
 
     Write-Host "Reenabling Windows Update Services..." -ForegroundColor Green
+    Write-WinUtilLog -Component "Updates" -Message "Restoring Windows Update service startup types."
 
     Write-Host "Restored BITS to Manual."
+    Write-WinUtilLog -Component "Updates" -Message "Restoring BITS service to Manual."
     Set-Service -Name BITS -StartupType Manual
 
     Write-Host "Restored wuauserv to Manual."
+    Write-WinUtilLog -Component "Updates" -Message "Restoring wuauserv service to Manual."
     Set-Service -Name wuauserv -StartupType Manual
 
     Write-Host "Restored UsoSvc to Automatic."
+    Write-WinUtilLog -Component "Updates" -Message "Starting UsoSvc service and restoring startup type to Automatic."
     Start-Service -Name UsoSvc
     Set-Service -Name UsoSvc -StartupType Automatic
 
     Write-Host "Restored WaaSMedicSvc to Manual."
+    Write-WinUtilLog -Component "Updates" -Message "Restoring WaaSMedicSvc service to Manual."
     Set-Service -Name WaaSMedicSvc -StartupType Manual
 
     Write-Host "Enabling update related scheduled tasks..." -ForegroundColor Green
+    Write-WinUtilLog -Component "Updates" -Message "Enabling update related scheduled tasks."
 
     $Tasks =
         '\Microsoft\Windows\InstallService\*',
@@ -49,6 +58,7 @@ function Invoke-WPFUpdatesdefault {
     }
 
     Write-Host "Windows Local Policies Reset to Default."
+    Write-WinUtilLog -Component "Updates" -Message "Resetting local security policy to defaults with secedit."
     secedit /configure /cfg "$Env:SystemRoot\inf\defltbase.inf" /db defltbase.sdb
 
     Write-Host "===================================================" -ForegroundColor Green
@@ -56,4 +66,5 @@ function Invoke-WPFUpdatesdefault {
     Write-Host "===================================================" -ForegroundColor Green
 
     Write-Host "Note: You must restart your system in order for all changes to take effect." -ForegroundColor Yellow
+    Write-WinUtilLog -Component "Updates" -Message "Windows Update default workflow completed. Restart required."
 }
diff --git a/functions/public/Invoke-WPFUpdatesdisable.ps1 b/functions/public/Invoke-WPFUpdatesdisable.ps1
index 6a65f76e..d020d9b6 100644
--- a/functions/public/Invoke-WPFUpdatesdisable.ps1
+++ b/functions/public/Invoke-WPFUpdatesdisable.ps1
@@ -9,8 +9,10 @@ function Invoke-WPFUpdatesdisable {
 
     #>
     $ErrorActionPreference = 'SilentlyContinue'
+    Write-WinUtilLog -Component "Updates" -Message "Disabling Windows Update settings."
 
     Write-Host "Configuring registry settings..." -ForegroundColor Yellow
+    Write-WinUtilLog -Component "Updates" -Message "Configuring Windows Update registry policy values for disable mode."
     New-Item -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Force
 
     Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Name "NoAutoUpdate" -Type DWord -Value 1
@@ -20,22 +22,28 @@ function Invoke-WPFUpdatesdisable {
     Set-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\DeliveryOptimization\Config" -Name "DODownloadMode" -Type DWord -Value 0
 
     Write-Host "Hiding Windows Updates from settings..."
+    Write-WinUtilLog -Component "Updates" -Message "Hiding Windows Update settings page."
     Set-ItemProperty -Path HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer -Name SettingsPageVisibility -Value hide:windowsupdate
 
     Write-Host "Disabled BITS Service."
+    Write-WinUtilLog -Component "Updates" -Message "Disabling BITS service."
     Set-Service -Name BITS -StartupType Disabled
 
     Write-Host "Disabled wuauserv Service."
+    Write-WinUtilLog -Component "Updates" -Message "Disabling wuauserv service."
     Set-Service -Name wuauserv -StartupType Disabled
 
     Write-Host "Disabled UsoSvc Service."
+    Write-WinUtilLog -Component "Updates" -Message "Stopping and disabling UsoSvc service."
     Stop-Service -Name UsoSvc -Force
     Set-Service -Name UsoSvc -StartupType Disabled
 
     Remove-Item "C:\Windows\SoftwareDistribution\*" -Recurse -Force
     Write-Host "Cleared SoftwareDistribution folder."
+    Write-WinUtilLog -Component "Updates" -Message "Cleared SoftwareDistribution folder."
 
     Write-Host "Disabling update related scheduled tasks..." -ForegroundColor Yellow
+    Write-WinUtilLog -Component "Updates" -Message "Disabling update related scheduled tasks."
 
     $Tasks =
         '\Microsoft\Windows\InstallService\*',
@@ -54,4 +62,5 @@ function Invoke-WPFUpdatesdisable {
     Write-Host "=================================" -ForegroundColor Green
 
     Write-Host "Note: You must restart your system in order for all changes to take effect." -ForegroundColor Yellow
+    Write-WinUtilLog -Component "Updates" -Message "Windows Update disable workflow completed. Restart required."
 }
diff --git a/functions/public/Invoke-WPFUpdatessecurity.ps1 b/functions/public/Invoke-WPFUpdatessecurity.ps1
index 97ef2688..5c5e97c6 100644
--- a/functions/public/Invoke-WPFUpdatessecurity.ps1
+++ b/functions/public/Invoke-WPFUpdatessecurity.ps1
@@ -14,6 +14,8 @@ function Invoke-WPFUpdatessecurity {
     #>
 
     Write-Host "Disabling driver offering through Windows Update..."
+    Write-WinUtilLog -Component "Updates" -Message "Applying recommended Windows Update settings."
+    Write-WinUtilLog -Component "Updates" -Message "Disabling driver offering through Windows Update."
 
     New-Item -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\Device Metadata" -Force
     Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\Device Metadata" -Name "PreventDeviceMetadataFromNetwork" -Type DWord -Value 1
@@ -28,6 +30,7 @@ function Invoke-WPFUpdatessecurity {
     Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" -Name "ExcludeWUDriversInQualityUpdate" -Type DWord -Value 1
 
     Write-Host "Setting cumulative updates back by 1 year and security updates by 4 days..."
+    Write-WinUtilLog -Component "Updates" -Message "Deferring feature updates by 365 days and quality updates by 4 days."
 
     New-Item -Path "HKLM:\SOFTWARE\Microsoft\WindowsUpdate\UX\Settings" -Force
 
@@ -36,6 +39,7 @@ function Invoke-WPFUpdatessecurity {
     Set-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\WindowsUpdate\UX\Settings" -Name "DeferQualityUpdatesPeriodInDays" -Type DWord -Value 4
 
     Write-Host "Disabling Windows Update automatic restart..."
+    Write-WinUtilLog -Component "Updates" -Message "Disabling Windows Update automatic restart while users are logged in."
 
     New-Item -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Force
     Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Name "NoAutoRebootWithLoggedOnUsers" -Type DWord -Value 1
@@ -44,4 +48,5 @@ function Invoke-WPFUpdatessecurity {
     Write-Host "================================="
     Write-Host "-- Updates Set to Recommended ---"
     Write-Host "================================="
+    Write-WinUtilLog -Component "Updates" -Message "Recommended Windows Update settings workflow completed."
 }
diff --git a/functions/public/Invoke-WPFtweaksbutton.ps1 b/functions/public/Invoke-WPFtweaksbutton.ps1
index 1c413a66..f6186c40 100644
--- a/functions/public/Invoke-WPFtweaksbutton.ps1
+++ b/functions/public/Invoke-WPFtweaksbutton.ps1
@@ -22,6 +22,7 @@ function Invoke-WPFtweaksbutton {
   $tweaksToRun = @($Tweaks | Where-Object { $_ -ne $restorePointTweak })
   $totalSteps = [Math]::Max($Tweaks.Count, 1)
   $completedSteps = 0
+  Write-WinUtilLog -Component "Tweaks" -Message "Tweaks requested: $(@($Tweaks).Count) selected tweak(s), DNS provider: $dnsProvider"
 
   if ($tweaks.count -eq 0 -and $dnsProvider -eq "Default") {
     $msg = "Please check the tweaks you wish to perform."
@@ -39,6 +40,7 @@ function Invoke-WPFtweaksbutton {
     }
 
     Set-WinUtilProgressBar -Label "Creating restore point" -Percent 0
+    Write-WinUtilLog -Component "Tweaks" -Message "Creating restore point before applying selected tweaks."
     Invoke-WinUtilTweaks $restorePointTweak
     $completedSteps = 1
 
@@ -49,6 +51,7 @@ function Invoke-WPFtweaksbutton {
       Write-Host "================================="
       Write-Host "--     Tweaks are Finished    ---"
       Write-Host "================================="
+      Write-WinUtilLog -Component "Tweaks" -Message "Tweaks workflow completed after restore point."
       return
     }
   }
@@ -82,5 +85,6 @@ function Invoke-WPFtweaksbutton {
     Write-Host "================================="
     Write-Host "--     Tweaks are Finished    ---"
     Write-Host "================================="
+    Write-WinUtilLog -Component "Tweaks" -Message "Tweaks workflow completed."
   }
 }
diff --git a/functions/public/Invoke-WPFundoall.ps1 b/functions/public/Invoke-WPFundoall.ps1
index 6bde6d13..230dce52 100644
--- a/functions/public/Invoke-WPFundoall.ps1
+++ b/functions/public/Invoke-WPFundoall.ps1
@@ -24,6 +24,7 @@ function Invoke-WPFundoall {
         param($tweaks)
 
         $sync.ProcessRunning = $true
+        Write-WinUtilLog -Component "Tweaks" -Message "Undo tweaks requested: $(@($tweaks).Count) selected tweak(s)."
         if ($tweaks.count -eq 1) {
             Invoke-WPFUIThread -ScriptBlock { Set-WinUtilTaskbaritem -state "Indeterminate" -value 0.01 -overlay "logo" }
         } else {
@@ -43,6 +44,7 @@ function Invoke-WPFundoall {
         Write-Host "=================================="
         Write-Host "---  Undo Tweaks are Finished  ---"
         Write-Host "=================================="
+        Write-WinUtilLog -Component "Tweaks" -Message "Undo tweaks workflow completed."
 
     }
 }
diff --git a/pester/appx.Tests.ps1 b/pester/appx.Tests.ps1
new file mode 100644
index 00000000..d1b459f9
--- /dev/null
+++ b/pester/appx.Tests.ps1
@@ -0,0 +1,259 @@
+#===========================================================================
+# Tests - AppX Removal
+#===========================================================================
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+    . (Join-Path $script:repoRoot "functions\private\Remove-WinUtilAPPX.ps1")
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFAppxRemoval.ps1")
+
+    function Write-WinUtilLog {
+        param($Message, $Level, $Component)
+    }
+    function Show-WinUtilMessage {
+        param($Message, $Title, $Button, $Icon)
+    }
+    function Invoke-WPFRunspace {
+        param($ArgumentList, $ParameterList, [scriptblock]$ScriptBlock)
+    }
+    function Get-AppxPackage {
+        param($Name, [switch]$AllUsers)
+    }
+    function Remove-AppxPackage {
+        param(
+            [Parameter(ValueFromPipeline = $true)]
+            $InputObject,
+            [switch]$AllUsers
+        )
+        process { }
+    }
+    function Get-AppxProvisionedPackage {
+        param([switch]$Online)
+    }
+    function Remove-AppxProvisionedPackage {
+        param(
+            [Parameter(ValueFromPipeline = $true)]
+            $InputObject,
+            [switch]$Online
+        )
+        process { }
+    }
+    function Get-Package {
+        param($Name, $ErrorAction)
+    }
+    function Uninstall-Package {
+        param(
+            [Parameter(ValueFromPipeline = $true)]
+            $InputObject,
+            [switch]$Force
+        )
+        process { }
+    }
+}
+
+Describe "Remove-WinUtilAPPX" {
+    BeforeEach {
+        Mock Write-Host { }
+        Mock Write-WinUtilLog { }
+        Mock Get-AppxPackage {
+            [pscustomobject]@{
+                Name = $Name
+            }
+        }
+        Mock Remove-AppxPackage { }
+        Mock Get-AppxProvisionedPackage {
+            @(
+                [pscustomobject]@{ DisplayName = "Microsoft.XboxGamingOverlay" }
+                [pscustomobject]@{ DisplayName = "Microsoft.WindowsCalculator" }
+            )
+        }
+        Mock Remove-AppxProvisionedPackage { }
+    }
+
+    It "removes matching installed and provisioned AppX packages" {
+        Remove-WinUtilAPPX -Name "Microsoft.Xbox*"
+
+        Should -Invoke -CommandName Get-AppxPackage -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "Microsoft.Xbox*" -and $AllUsers -eq $true
+        }
+        Should -Invoke -CommandName Remove-AppxPackage -Times 1 -Exactly -ParameterFilter {
+            $InputObject.Name -eq "Microsoft.Xbox*" -and $AllUsers -eq $true
+        }
+        Should -Invoke -CommandName Get-AppxProvisionedPackage -Times 1 -Exactly -ParameterFilter {
+            $Online -eq $true
+        }
+        Should -Invoke -CommandName Remove-AppxProvisionedPackage -Times 1 -Exactly -ParameterFilter {
+            $InputObject.DisplayName -eq "Microsoft.XboxGamingOverlay" -and $Online -eq $true
+        }
+    }
+}
+
+Describe "Invoke-WPFAppxRemoval entrypoint" {
+    BeforeEach {
+        $script:sync = [Hashtable]::Synchronized(@{
+            ProcessRunning = $false
+            selectedAppx = [System.Collections.Generic.List[string]]::new()
+            configs = @{
+                appxHashtable = @{}
+            }
+        })
+        $script:capturedAppxScriptBlock = $null
+        $script:capturedAppxParameterList = $null
+
+        Mock Show-WinUtilMessage { "OK" }
+        Mock Invoke-WPFRunspace {
+            $script:capturedAppxScriptBlock = $ScriptBlock
+            $script:capturedAppxParameterList = $ParameterList
+            [pscustomobject]@{ MockHandle = $true }
+        }
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name capturedAppxScriptBlock -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name capturedAppxParameterList -Scope Script -ErrorAction SilentlyContinue
+    }
+
+    It "prompts and exits when no AppX packages are selected" {
+        Invoke-WPFAppxRemoval
+
+        Should -Invoke -CommandName Show-WinUtilMessage -Times 1 -Exactly -ParameterFilter {
+            $Message -eq "No AppX Package selected" -and
+                $Title -eq "Error" -and
+                $Button -eq "OK" -and
+                $Icon -eq "Error"
+        }
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 0 -Exactly
+    }
+
+    It "passes selected AppX keys and app metadata to the removal runspace" {
+        $script:sync.selectedAppx.Add("WPFAppxExample")
+        $script:sync.configs.appxHashtable["WPFAppxExample"] = [pscustomobject]@{
+            Content = "Example App"
+            PackageId = "Example.Package"
+        }
+
+        Invoke-WPFAppxRemoval
+
+        Should -Invoke -CommandName Show-WinUtilMessage -Times 0 -Exactly
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 1 -Exactly -ParameterFilter {
+            $ScriptBlock -is [scriptblock] -and
+                $ParameterList.Count -eq 2 -and
+                $ParameterList[0][0] -eq "selected" -and
+                $ParameterList[0][1][0] -eq "WPFAppxExample" -and
+                $ParameterList[1][0] -eq "apps" -and
+                $ParameterList[1][1]["WPFAppxExample"].PackageId -eq "Example.Package"
+        }
+    }
+}
+
+Describe "Invoke-WPFAppxRemoval runspace body" {
+    BeforeEach {
+        $script:sync = [Hashtable]::Synchronized(@{
+            ProcessRunning = $false
+            selectedAppx = [System.Collections.Generic.List[string]]::new()
+            configs = @{
+                appxHashtable = @{}
+            }
+        })
+        $script:capturedAppxScriptBlock = $null
+        $script:apps = @{
+            WPFAppxExample = [pscustomobject]@{
+                Content = "Example App"
+                PackageId = "Example.Package"
+            }
+            WPFAppxMicrosoft_XboxGamingOverlay = [pscustomobject]@{
+                Content = "Xbox Gaming Overlay"
+                PackageId = "Microsoft.XboxGamingOverlay"
+            }
+            WPFAppxMicrosoft_WindowsNotepad = [pscustomobject]@{
+                Content = "Notepad"
+                PackageId = "Microsoft.WindowsNotepad"
+            }
+            WPFAppxMSTeams = [pscustomobject]@{
+                Content = "Microsoft Teams"
+                PackageId = "MSTeams"
+            }
+        }
+
+        Mock Invoke-WPFRunspace {
+            $script:capturedAppxScriptBlock = $ScriptBlock
+            [pscustomobject]@{ MockHandle = $true }
+        }
+        Mock Show-WinUtilMessage { "OK" }
+        Mock Write-Host { }
+        Mock Write-WinUtilLog { }
+        Mock Stop-Process { }
+        Mock Set-ItemProperty { }
+        Mock Get-AppxPackage {
+            [pscustomobject]@{
+                Name = $Name
+            }
+        }
+        Mock Remove-AppxPackage { }
+        Mock Get-Package {
+            [pscustomobject]@{
+                Name = "Microsoft Teams Meeting Add-in"
+            }
+        }
+        Mock Uninstall-Package { }
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name capturedAppxScriptBlock -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name apps -Scope Script -ErrorAction SilentlyContinue
+    }
+
+    It "removes selected AppX packages and clears ProcessRunning when finished" {
+        $selected = @("WPFAppxExample")
+        $script:sync.selectedAppx.Add("WPFAppxExample")
+        $script:sync.configs.appxHashtable = $script:apps
+
+        Invoke-WPFAppxRemoval
+        & $script:capturedAppxScriptBlock -selected $selected -apps $script:apps
+
+        Should -Invoke -CommandName Get-AppxPackage -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "Example.Package" -and $AllUsers -eq $true
+        }
+        Should -Invoke -CommandName Remove-AppxPackage -Times 1 -Exactly -ParameterFilter {
+            $InputObject.Name -eq "Example.Package" -and $AllUsers -eq $true
+        }
+        $script:sync.ProcessRunning | Should -BeFalse
+    }
+
+    It "applies special cleanup for Xbox overlay, Notepad, and Teams selections" {
+        $selected = @(
+            "WPFAppxMicrosoft_XboxGamingOverlay",
+            "WPFAppxMicrosoft_WindowsNotepad",
+            "WPFAppxMSTeams"
+        )
+        foreach ($key in $selected) {
+            $script:sync.selectedAppx.Add($key)
+        }
+        $script:sync.configs.appxHashtable = $script:apps
+
+        Invoke-WPFAppxRemoval
+        & $script:capturedAppxScriptBlock -selected $selected -apps $script:apps
+
+        Should -Invoke -CommandName Stop-Process -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "GameBarFTServer"
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\GameDVR" -and
+                $Name -eq "AppCaptureEnabled" -and
+                $Value -eq 0
+        }
+        Should -Invoke -CommandName Stop-Process -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "dllhost"
+        }
+        Should -Invoke -CommandName Get-Package -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "Microsoft Teams*"
+        }
+        Should -Invoke -CommandName Uninstall-Package -Times 1 -Exactly -ParameterFilter {
+            $InputObject.Name -eq "Microsoft Teams Meeting Add-in" -and $Force -eq $true
+        }
+        Should -Invoke -CommandName Remove-AppxPackage -Times 3 -Exactly
+        $script:sync.ProcessRunning | Should -BeFalse
+    }
+}
diff --git a/pester/configs.Tests.ps1 b/pester/configs.Tests.ps1
index e90f9984..ee321360 100644
--- a/pester/configs.Tests.ps1
+++ b/pester/configs.Tests.ps1
@@ -2,7 +2,12 @@
 # Tests - Config Files
 #===========================================================================
 
+$repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
 $configRoot = Join-Path $PSScriptRoot "..\config"
+$functionRoot = Join-Path $repoRoot "functions"
+$xamlPath = Join-Path $repoRoot "xaml\inputXML.xaml"
+$mainScriptPath = Join-Path $repoRoot "scripts\main.ps1"
+$buttonScriptPath = Join-Path $repoRoot "functions\public\Invoke-WPFButton.ps1"
 $configCases = @(
     Get-ChildItem -Path $configRoot -Filter *.json | ForEach-Object {
         @{
@@ -12,6 +17,103 @@ $configCases = @(
     }
 )
 
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+    $script:configRoot = Join-Path $script:repoRoot "config"
+    $script:functionRoot = Join-Path $script:repoRoot "functions"
+    $script:xamlPath = Join-Path $script:repoRoot "xaml\inputXML.xaml"
+    $script:mainScriptPath = Join-Path $script:repoRoot "scripts\main.ps1"
+    $script:buttonScriptPath = Join-Path $script:repoRoot "functions\public\Invoke-WPFButton.ps1"
+
+function script:Get-WinUtilConfigObject {
+    param([string]$Name)
+
+    Get-Content -Path (Join-Path $script:configRoot "$Name.json") -Raw | ConvertFrom-Json
+}
+
+function script:Test-WinUtilHasProperty {
+    param(
+        [Parameter(Mandatory)]
+        [psobject]$Object,
+
+        [Parameter(Mandatory)]
+        [string]$Name
+    )
+
+    return @($Object.PSObject.Properties.Name) -contains $Name
+}
+
+function script:Test-WinUtilHasNonEmptyProperty {
+    param(
+        [Parameter(Mandatory)]
+        [psobject]$Object,
+
+        [Parameter(Mandatory)]
+        [string]$Name
+    )
+
+    if (-not (Test-WinUtilHasProperty -Object $Object -Name $Name)) {
+        return $false
+    }
+
+    $value = $Object.$Name
+    if ($null -eq $value) {
+        return $false
+    }
+
+    if ($value -is [string]) {
+        return -not [string]::IsNullOrWhiteSpace($value)
+    }
+
+    if ($value -is [array]) {
+        return @($value).Count -gt 0
+    }
+
+    return -not [string]::IsNullOrWhiteSpace([string]$value)
+}
+
+function script:Get-WinUtilMissingRequiredFields {
+    param(
+        [Parameter(Mandatory)]
+        [string]$EntryName,
+
+        [Parameter(Mandatory)]
+        [psobject]$Entry,
+
+        [Parameter(Mandatory)]
+        [string[]]$RequiredFields
+    )
+
+    foreach ($field in $RequiredFields) {
+        if (-not (Test-WinUtilHasNonEmptyProperty -Object $Entry -Name $field)) {
+            "$EntryName missing $field"
+        }
+    }
+}
+
+function script:Get-WinUtilTopLevelFunctionNames {
+    Get-ChildItem -Path $script:functionRoot -Filter *.ps1 -Recurse | ForEach-Object {
+        $tokens = $null
+        $syntaxErrors = $null
+        $ast = [System.Management.Automation.Language.Parser]::ParseFile($_.FullName, [ref]$tokens, [ref]$syntaxErrors)
+        if ($syntaxErrors.Count -ne 0) {
+            throw ($syntaxErrors | Out-String)
+        }
+
+        $ast.EndBlock.Statements |
+            Where-Object { $_ -is [System.Management.Automation.Language.FunctionDefinitionAst] } |
+            ForEach-Object { $_.Name }
+    } | Sort-Object -Unique
+}
+
+function script:Get-WinUtilButtonSwitchNames {
+    $buttonSource = Get-Content -Path $script:buttonScriptPath -Raw
+    [regex]::Matches($buttonSource, '"(WPF[A-Za-z0-9_]+)"\s*\{') |
+        ForEach-Object { $_.Groups[1].Value } |
+        Sort-Object -Unique
+}
+}
+
 Describe "Config files" {
     foreach ($configCase in $configCases) {
         It "imports $($configCase.Name) with no JSON errors" -TestCases $configCase {
@@ -108,3 +210,341 @@ Describe "Tweaks config" {
         }
     }
 }
+
+Describe "Preset config" {
+    It "references existing config entries or supported actions" {
+        $preset = Get-WinUtilConfigObject -Name "preset"
+        $applications = Get-WinUtilConfigObject -Name "applications"
+        $tweaks = Get-WinUtilConfigObject -Name "tweaks"
+        $feature = Get-WinUtilConfigObject -Name "feature"
+        $appx = Get-WinUtilConfigObject -Name "appx"
+
+        $validReferences = @(
+            $tweaks.PSObject.Properties.Name
+            $feature.PSObject.Properties.Name
+            $appx.PSObject.Properties.Name
+            $applications.PSObject.Properties.Name | ForEach-Object { "WPFInstall$_" }
+            Get-WinUtilButtonSwitchNames
+        ) | Sort-Object -Unique
+
+        $invalidReferences = New-Object System.Collections.Generic.List[string]
+        foreach ($presetEntry in $preset.PSObject.Properties) {
+            foreach ($reference in @($presetEntry.Value)) {
+                if ($validReferences -notcontains $reference) {
+                    $invalidReferences.Add("$($presetEntry.Name) references missing item $reference")
+                }
+            }
+        }
+
+        if ($invalidReferences.Count -gt 0) {
+            throw ($invalidReferences -join "`n")
+        }
+    }
+}
+
+Describe "App navigation config" {
+    It "is wired to an existing XAML target grid" {
+        $mainScript = Get-Content -Path $script:mainScriptPath -Raw
+        $targetGridMatch = [regex]::Match(
+            $mainScript,
+            'Invoke-WPFUIElements\s+-configVariable\s+\$sync\.configs\.appnavigation\s+-targetGridName\s+"([^"]+)"'
+        )
+
+        if (-not $targetGridMatch.Success) {
+            throw "scripts/main.ps1 does not wire appnavigation through Invoke-WPFUIElements."
+        }
+
+        $xamlText = Get-Content -Path $script:xamlPath -Raw
+        $targetGridName = $targetGridMatch.Groups[1].Value
+        if ($xamlText -notmatch "Name=`"$([regex]::Escape($targetGridName))`"") {
+            throw "appnavigation target grid '$targetGridName' was not found in xaml/inputXML.xaml."
+        }
+    }
+
+    It "contains renderable entries with valid button and radio groups" {
+        $appnavigation = Get-WinUtilConfigObject -Name "appnavigation"
+        $feature = Get-WinUtilConfigObject -Name "feature"
+        $requiredFields = @("Content", "Category", "Type", "Order", "Description")
+        $allowedTypes = @("Button", "RadioButton", "Note")
+        $supportedButtons = @(
+            Get-WinUtilButtonSwitchNames
+            $feature.PSObject.Properties.Name
+        ) | Sort-Object -Unique
+        $invalidEntries = New-Object System.Collections.Generic.List[string]
+
+        foreach ($entry in $appnavigation.PSObject.Properties) {
+            foreach ($missingField in (Get-WinUtilMissingRequiredFields -EntryName $entry.Name -Entry $entry.Value -RequiredFields $requiredFields)) {
+                $invalidEntries.Add($missingField)
+            }
+
+            if ($allowedTypes -notcontains $entry.Value.Type) {
+                $invalidEntries.Add("$($entry.Name) has unsupported Type '$($entry.Value.Type)'")
+            }
+
+            if ($entry.Value.Type -eq "Button" -and $supportedButtons -notcontains $entry.Name) {
+                $invalidEntries.Add("$($entry.Name) is not handled by Invoke-WPFButton or feature config")
+            }
+
+            if ($entry.Value.Type -eq "RadioButton") {
+                if (-not (Test-WinUtilHasNonEmptyProperty -Object $entry.Value -Name "GroupName")) {
+                    $invalidEntries.Add("$($entry.Name) missing GroupName")
+                }
+
+                if (-not (Test-WinUtilHasProperty -Object $entry.Value -Name "Checked")) {
+                    $invalidEntries.Add("$($entry.Name) missing Checked")
+                }
+            }
+        }
+
+        $radioButtons = @($appnavigation.PSObject.Properties | Where-Object { $_.Value.Type -eq "RadioButton" })
+        foreach ($group in ($radioButtons | Group-Object -Property { $_.Value.GroupName })) {
+            if ([string]::IsNullOrWhiteSpace($group.Name)) {
+                $invalidEntries.Add("RadioButton group name is blank")
+                continue
+            }
+
+            $checkedCount = @($group.Group | Where-Object { $_.Value.Checked -eq $true }).Count
+            if ($checkedCount -ne 1) {
+                $invalidEntries.Add("RadioButton group '$($group.Name)' has $checkedCount checked entries")
+            }
+        }
+
+        if ($invalidEntries.Count -gt 0) {
+            throw ($invalidEntries -join "`n")
+        }
+    }
+}
+
+Describe "UI-rendered config entries" {
+    It "contains required AppX fields" {
+        $appx = Get-WinUtilConfigObject -Name "appx"
+        $requiredFields = @("Category", "Content", "Description", "Panel", "PackageId")
+        $invalidEntries = New-Object System.Collections.Generic.List[string]
+
+        foreach ($entry in $appx.PSObject.Properties) {
+            foreach ($missingField in (Get-WinUtilMissingRequiredFields -EntryName $entry.Name -Entry $entry.Value -RequiredFields $requiredFields)) {
+                $invalidEntries.Add($missingField)
+            }
+        }
+
+        if ($invalidEntries.Count -gt 0) {
+            throw ($invalidEntries -join "`n")
+        }
+    }
+
+    It "contains required DNS fields with parseable IP addresses" {
+        $dns = Get-WinUtilConfigObject -Name "dns"
+        $requiredFields = @("Primary", "Secondary", "Primary6", "Secondary6")
+        $invalidEntries = New-Object System.Collections.Generic.List[string]
+
+        foreach ($entry in $dns.PSObject.Properties) {
+            foreach ($missingField in (Get-WinUtilMissingRequiredFields -EntryName $entry.Name -Entry $entry.Value -RequiredFields $requiredFields)) {
+                $invalidEntries.Add($missingField)
+            }
+
+            foreach ($field in $requiredFields) {
+                if (-not (Test-WinUtilHasNonEmptyProperty -Object $entry.Value -Name $field)) {
+                    continue
+                }
+
+                try {
+                    [System.Net.IPAddress]::Parse([string]$entry.Value.$field) | Out-Null
+                } catch {
+                    $invalidEntries.Add("$($entry.Name) $field is not a parseable IP address")
+                }
+            }
+        }
+
+        if ($invalidEntries.Count -gt 0) {
+            throw ($invalidEntries -join "`n")
+        }
+    }
+
+    It "contains required feature fields and valid configured functions" {
+        $feature = Get-WinUtilConfigObject -Name "feature"
+        $functionNames = Get-WinUtilTopLevelFunctionNames
+        $requiredFields = @("Content", "category", "panel", "link")
+        $invalidEntries = New-Object System.Collections.Generic.List[string]
+
+        foreach ($entry in $feature.PSObject.Properties) {
+            foreach ($missingField in (Get-WinUtilMissingRequiredFields -EntryName $entry.Name -Entry $entry.Value -RequiredFields $requiredFields)) {
+                $invalidEntries.Add($missingField)
+            }
+
+            if ($entry.Value.Type -and $entry.Value.Type -ne "Button") {
+                $invalidEntries.Add("$($entry.Name) has unsupported Type '$($entry.Value.Type)'")
+            }
+
+            if ($entry.Value.Type -eq "Button") {
+                if (-not $entry.Value.function -and -not $entry.Value.InvokeScript) {
+                    $invalidEntries.Add("$($entry.Name) button missing function or InvokeScript")
+                }
+            } else {
+                if (-not (Test-WinUtilHasNonEmptyProperty -Object $entry.Value -Name "Description")) {
+                    $invalidEntries.Add("$($entry.Name) missing Description")
+                }
+
+                if (-not $entry.Value.feature -and -not $entry.Value.InvokeScript) {
+                    $invalidEntries.Add("$($entry.Name) missing feature or InvokeScript action")
+                }
+            }
+
+            if ($entry.Value.function -and $functionNames -notcontains $entry.Value.function) {
+                $invalidEntries.Add("$($entry.Name) references missing function $($entry.Value.function)")
+            }
+        }
+
+        if ($invalidEntries.Count -gt 0) {
+            throw ($invalidEntries -join "`n")
+        }
+    }
+
+    It "contains required tweak fields and valid action metadata" {
+        $tweaks = Get-WinUtilConfigObject -Name "tweaks"
+        $requiredFields = @("Content", "category", "panel", "link")
+        $allowedTypes = @("Button", "Combobox", "Toggle", "ToggleButton")
+        $supportedButtons = Get-WinUtilButtonSwitchNames
+        $invalidEntries = New-Object System.Collections.Generic.List[string]
+
+        foreach ($entry in $tweaks.PSObject.Properties) {
+            foreach ($missingField in (Get-WinUtilMissingRequiredFields -EntryName $entry.Name -Entry $entry.Value -RequiredFields $requiredFields)) {
+                $invalidEntries.Add($missingField)
+            }
+
+            if ($entry.Value.Type -and $allowedTypes -notcontains $entry.Value.Type) {
+                $invalidEntries.Add("$($entry.Name) has unsupported Type '$($entry.Value.Type)'")
+            }
+
+            if ($entry.Value.Type -eq "Button") {
+                if ($supportedButtons -notcontains $entry.Name) {
+                    $invalidEntries.Add("$($entry.Name) is not handled by Invoke-WPFButton")
+                }
+            } elseif ($entry.Value.Type -eq "Combobox") {
+                if (-not (Test-WinUtilHasNonEmptyProperty -Object $entry.Value -Name "ComboItems")) {
+                    $invalidEntries.Add("$($entry.Name) combobox missing ComboItems")
+                }
+            } else {
+                if (-not (Test-WinUtilHasNonEmptyProperty -Object $entry.Value -Name "Description")) {
+                    $invalidEntries.Add("$($entry.Name) missing Description")
+                }
+
+                if (-not $entry.Value.registry -and -not $entry.Value.service -and -not $entry.Value.InvokeScript -and -not $entry.Value.appx) {
+                    $invalidEntries.Add("$($entry.Name) missing registry, service, InvokeScript, or appx action")
+                }
+            }
+
+            foreach ($registryEntry in @($entry.Value.registry)) {
+                if ($null -eq $registryEntry) { continue }
+
+                foreach ($missingField in (Get-WinUtilMissingRequiredFields -EntryName "$($entry.Name),registry" -Entry $registryEntry -RequiredFields @("Path", "Name", "Type", "Value", "OriginalValue"))) {
+                    $invalidEntries.Add($missingField)
+                }
+            }
+
+            foreach ($serviceEntry in @($entry.Value.service)) {
+                if ($null -eq $serviceEntry) { continue }
+
+                foreach ($missingField in (Get-WinUtilMissingRequiredFields -EntryName "$($entry.Name),service" -Entry $serviceEntry -RequiredFields @("Name", "StartupType", "OriginalType"))) {
+                    $invalidEntries.Add($missingField)
+                }
+            }
+        }
+
+        if ($invalidEntries.Count -gt 0) {
+            throw ($invalidEntries -join "`n")
+        }
+    }
+
+    It "defines theme resources required by XAML rendering" {
+        $themes = Get-WinUtilConfigObject -Name "themes"
+        $invalidEntries = New-Object System.Collections.Generic.List[string]
+
+        foreach ($themeName in @("shared", "Light", "Dark")) {
+            if (-not (Test-WinUtilHasProperty -Object $themes -Name $themeName)) {
+                $invalidEntries.Add("themes.json missing $themeName")
+                continue
+            }
+
+            foreach ($property in $themes.$themeName.PSObject.Properties) {
+                if ([string]::IsNullOrWhiteSpace([string]$property.Value)) {
+                    $invalidEntries.Add("$themeName.$($property.Name) is blank")
+                }
+            }
+        }
+
+        $lightKeys = @($themes.Light.PSObject.Properties.Name)
+        $darkKeys = @($themes.Dark.PSObject.Properties.Name)
+        foreach ($key in $lightKeys) {
+            if ($darkKeys -notcontains $key) {
+                $invalidEntries.Add("Dark theme missing $key")
+            }
+        }
+        foreach ($key in $darkKeys) {
+            if ($lightKeys -notcontains $key) {
+                $invalidEntries.Add("Light theme missing $key")
+            }
+        }
+
+        $xamlText = Get-Content -Path $script:xamlPath -Raw
+        $dynamicResourceNames = @(
+            [regex]::Matches($xamlText, '\{DynamicResource\s+([^\}\s]+)') |
+                ForEach-Object { $_.Groups[1].Value }
+        ) | Sort-Object -Unique
+        $xamlDefinedResourceNames = @(
+            [regex]::Matches($xamlText, 'x:Key="([^"]+)"') |
+                ForEach-Object { $_.Groups[1].Value }
+        ) | Sort-Object -Unique
+        $themeResourceNames = @(
+            $themes.shared.PSObject.Properties.Name
+            $themes.Light.PSObject.Properties.Name
+            $themes.Dark.PSObject.Properties.Name
+            "CBorderColor"
+            "CButtonBackgroundMouseoverColor"
+        ) | Sort-Object -Unique
+
+        foreach ($resourceName in $dynamicResourceNames) {
+            if ($xamlDefinedResourceNames -notcontains $resourceName -and $themeResourceNames -notcontains $resourceName) {
+                $invalidEntries.Add("XAML DynamicResource '$resourceName' is not defined in themes.json or XAML resources")
+            }
+        }
+
+        if ($invalidEntries.Count -gt 0) {
+            throw ($invalidEntries -join "`n")
+        }
+    }
+}
+
+Describe "Embedded config scripts" {
+    It "parse as PowerShell scriptblocks" {
+        $invalidScripts = New-Object System.Collections.Generic.List[string]
+
+        foreach ($configFile in (Get-ChildItem -Path $script:configRoot -Filter *.json)) {
+            $config = Get-Content -Path $configFile.FullName -Raw | ConvertFrom-Json
+            foreach ($entry in $config.PSObject.Properties) {
+                foreach ($field in @("InvokeScript", "UndoScript")) {
+                    if (-not (Test-WinUtilHasProperty -Object $entry.Value -Name $field)) {
+                        continue
+                    }
+
+                    $index = 0
+                    foreach ($scriptText in @($entry.Value.$field)) {
+                        $index++
+                        if ([string]::IsNullOrWhiteSpace([string]$scriptText)) {
+                            continue
+                        }
+
+                        try {
+                            [scriptblock]::Create([string]$scriptText) | Out-Null
+                        } catch {
+                            $invalidScripts.Add("$($configFile.Name):$($entry.Name).$field[$index] $($psitem.Exception.Message)")
+                        }
+                    }
+                }
+            }
+        }
+
+        if ($invalidScripts.Count -gt 0) {
+            throw ($invalidScripts -join "`n")
+        }
+    }
+}
diff --git a/pester/install-workflow.Tests.ps1 b/pester/install-workflow.Tests.ps1
new file mode 100644
index 00000000..f4d633cb
--- /dev/null
+++ b/pester/install-workflow.Tests.ps1
@@ -0,0 +1,414 @@
+#===========================================================================
+# Tests - Install and Uninstall Workflows
+#===========================================================================
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+
+    if (-not ("PackageManagers" -as [type])) {
+        Add-Type @"
+public enum PackageManagers
+{
+    Winget,
+    Choco
+}
+"@
+    }
+
+    . (Join-Path $script:repoRoot "functions\private\Get-WinUtilPackageLogSummary.ps1")
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFInstall.ps1")
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFUnInstall.ps1")
+
+    function Show-WinUtilMessage {
+        param($Message, $Title, $Button, $Icon)
+    }
+    function Invoke-WPFRunspace {
+        param($ArgumentList, $ParameterList, [scriptblock]$ScriptBlock)
+    }
+    function Get-WinUtilSelectedPackages {
+        param($PackageList, [PackageManagers]$Preference)
+    }
+    function Show-WPFInstallAppBusy {
+        param($text)
+    }
+    function Hide-WPFInstallAppBusy { }
+    function Install-WinUtilWinget { }
+    function Install-WinUtilChoco { }
+    function Install-WinUtilProgramWinget {
+        param($Action, $Programs)
+    }
+    function Install-WinUtilProgramChoco {
+        param($Action, $Programs)
+    }
+    function Invoke-WPFUIThread {
+        param([scriptblock]$ScriptBlock)
+    }
+    function Write-WinUtilLog {
+        param($Message, $Level, $Component)
+    }
+
+    function script:New-WinUtilPackage {
+        param(
+            [string]$Name = "Git",
+            [string]$Winget = "Git.Git",
+            [string]$Choco = "git"
+        )
+
+        [pscustomobject]@{
+            Name = $Name
+            Description = "$Name package"
+            winget = $Winget
+            choco = $Choco
+        }
+    }
+
+    function script:New-WinUtilInstallTestContext {
+        param(
+            [bool]$ProcessRunning = $false,
+            [object[]]$Packages = @()
+        )
+
+        $applications = @{}
+        $selectedApps = [System.Collections.Generic.List[string]]::new()
+
+        for ($i = 0; $i -lt $Packages.Count; $i++) {
+            $key = "WPFInstallTest$i"
+            $applications[$key] = $Packages[$i]
+            $selectedApps.Add($key)
+        }
+
+        $script:AppTitle = "Winutil"
+        $script:sync = [Hashtable]::Synchronized(@{
+            ProcessRunning = $ProcessRunning
+            selectedApps = $selectedApps
+            preferences = [pscustomobject]@{
+                packagemanager = [PackageManagers]::Winget
+            }
+            configs = @{
+                applicationsHashtable = $applications
+            }
+        })
+    }
+
+    function script:New-WinUtilPackageSplit {
+        param(
+            [string[]]$Winget = @(),
+            [string[]]$Choco = @()
+        )
+
+        $packages = @{}
+        $packages[[PackageManagers]::Winget] = [System.Collections.Generic.List[string]]::new()
+        $packages[[PackageManagers]::Choco] = [System.Collections.Generic.List[string]]::new()
+
+        foreach ($package in $Winget) {
+            $null = $packages[[PackageManagers]::Winget].Add($package)
+        }
+
+        foreach ($package in $Choco) {
+            $null = $packages[[PackageManagers]::Choco].Add($package)
+        }
+
+        $packages
+    }
+}
+
+Describe "Invoke-WPFInstall entrypoint" {
+    BeforeEach {
+        $script:package = New-WinUtilPackage
+        New-WinUtilInstallTestContext -Packages @($script:package)
+        $script:capturedInstallScriptBlock = $null
+        $script:capturedInstallParameterList = $null
+
+        Mock Show-WinUtilMessage { "OK" }
+        Mock Invoke-WPFRunspace {
+            $script:capturedInstallScriptBlock = $ScriptBlock
+            $script:capturedInstallParameterList = $ParameterList
+            [pscustomobject]@{ MockHandle = $true }
+        }
+        Mock Write-WinUtilLog { }
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name AppTitle -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name capturedInstallScriptBlock -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name capturedInstallParameterList -Scope Script -ErrorAction SilentlyContinue
+    }
+
+    It "queues selected packages with the configured package manager preference" {
+        Invoke-WPFInstall
+
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 1 -Exactly -ParameterFilter {
+            $ScriptBlock -is [scriptblock] -and
+                $ParameterList.Count -eq 2 -and
+                $ParameterList[0][0] -eq "PackagesToInstall" -and
+                @($ParameterList[0][1]).Count -eq 1 -and
+                @($ParameterList[0][1])[0].winget -eq "Git.Git" -and
+                $ParameterList[1][0] -eq "ManagerPreference" -and
+                $ParameterList[1][1] -eq [PackageManagers]::Winget
+        }
+        Should -Invoke -CommandName Show-WinUtilMessage -Times 0 -Exactly
+        Should -Invoke -CommandName Write-WinUtilLog -Times 1 -Exactly -ParameterFilter {
+            $Component -eq "Install" -and
+                $Message -eq "Install selected package(s): Git (winget: Git.Git)"
+        }
+    }
+
+    It "prompts and exits when no packages are selected" {
+        New-WinUtilInstallTestContext
+
+        Invoke-WPFInstall
+
+        Should -Invoke -CommandName Show-WinUtilMessage -Times 1 -Exactly -ParameterFilter {
+            $Message -eq "Please select the program(s) to install or upgrade." -and
+                $Title -eq "Winutil" -and
+                $Button -eq "OK" -and
+                $Icon -eq "Warning"
+        }
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 0 -Exactly
+    }
+
+    It "prompts and exits when another install process is running" {
+        New-WinUtilInstallTestContext -ProcessRunning $true -Packages @($script:package)
+
+        Invoke-WPFInstall
+
+        Should -Invoke -CommandName Show-WinUtilMessage -Times 1 -Exactly -ParameterFilter {
+            $Message -eq "[Invoke-WPFInstall] An Install process is currently running." -and
+                $Title -eq "Winutil" -and
+                $Button -eq "OK" -and
+                $Icon -eq "Warning"
+        }
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 0 -Exactly
+    }
+}
+
+Describe "Invoke-WPFInstall runspace body" {
+    BeforeEach {
+        $script:package = New-WinUtilPackage
+        New-WinUtilInstallTestContext -Packages @($script:package)
+        $script:capturedInstallScriptBlock = $null
+
+        Mock Show-WinUtilMessage { "OK" }
+        Mock Invoke-WPFRunspace {
+            $script:capturedInstallScriptBlock = $ScriptBlock
+            [pscustomobject]@{ MockHandle = $true }
+        }
+        Mock Get-WinUtilSelectedPackages {
+            New-WinUtilPackageSplit -Winget @("Git.Git") -Choco @("vlc")
+        }
+        Mock Show-WPFInstallAppBusy { }
+        Mock Hide-WPFInstallAppBusy { }
+        Mock Install-WinUtilWinget { }
+        Mock Install-WinUtilChoco { }
+        Mock Install-WinUtilProgramWinget { }
+        Mock Install-WinUtilProgramChoco { }
+        Mock Invoke-WPFUIThread { }
+        Mock Write-WinUtilLog { }
+        Mock Write-Host { }
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name AppTitle -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name capturedInstallScriptBlock -Scope Script -ErrorAction SilentlyContinue
+    }
+
+    It "installs split winget and choco packages and cleans up on success" {
+        Invoke-WPFInstall
+
+        & $script:capturedInstallScriptBlock -PackagesToInstall @($script:package) -ManagerPreference ([PackageManagers]::Winget)
+
+        Should -Invoke -CommandName Get-WinUtilSelectedPackages -Times 1 -Exactly -ParameterFilter {
+            @($PackageList).Count -eq 1 -and $Preference -eq [PackageManagers]::Winget
+        }
+        Should -Invoke -CommandName Show-WPFInstallAppBusy -Times 1 -Exactly -ParameterFilter {
+            $text -eq "Installing apps..."
+        }
+        Should -Invoke -CommandName Install-WinUtilWinget -Times 1 -Exactly
+        Should -Invoke -CommandName Install-WinUtilProgramWinget -Times 1 -Exactly -ParameterFilter {
+            $Action -eq "Install" -and @($Programs)[0] -eq "Git.Git"
+        }
+        Should -Invoke -CommandName Install-WinUtilChoco -Times 1 -Exactly
+        Should -Invoke -CommandName Install-WinUtilProgramChoco -Times 1 -Exactly -ParameterFilter {
+            $Action -eq "Install" -and @($Programs)[0] -eq "vlc"
+        }
+        Should -Invoke -CommandName Hide-WPFInstallAppBusy -Times 1 -Exactly
+        Should -Invoke -CommandName Invoke-WPFUIThread -Times 1 -Exactly -ParameterFilter {
+            $ScriptBlock.ToString() -like '*Set-WinUtilTaskbaritem -state "None" -overlay "checkmark"*'
+        }
+        $script:sync.ProcessRunning | Should -BeFalse
+    }
+
+    It "hides the busy overlay, sets taskbar error state, and clears ProcessRunning on failure" {
+        Mock Install-WinUtilProgramWinget { throw "winget failed" }
+
+        Invoke-WPFInstall
+
+        & $script:capturedInstallScriptBlock -PackagesToInstall @($script:package) -ManagerPreference ([PackageManagers]::Winget)
+
+        Should -Invoke -CommandName Hide-WPFInstallAppBusy -Times 1 -Exactly
+        Should -Invoke -CommandName Invoke-WPFUIThread -Times 1 -Exactly -ParameterFilter {
+            $ScriptBlock.ToString() -like '*Set-WinUtilTaskbaritem -state "Error" -overlay "warning"*'
+        }
+        Should -Invoke -CommandName Write-WinUtilLog -Times 1 -Exactly -ParameterFilter {
+            $Level -eq "ERROR" -and $Component -eq "Install" -and $Message -like "Install workflow failed:*"
+        }
+        $script:sync.ProcessRunning | Should -BeFalse
+    }
+}
+
+Describe "Invoke-WPFUnInstall entrypoint" {
+    BeforeEach {
+        $script:package = New-WinUtilPackage
+        New-WinUtilInstallTestContext -Packages @($script:package)
+        $script:capturedUninstallScriptBlock = $null
+        $script:capturedUninstallParameterList = $null
+
+        Mock Show-WinUtilMessage { "Yes" }
+        Mock Invoke-WPFRunspace {
+            $script:capturedUninstallScriptBlock = $ScriptBlock
+            $script:capturedUninstallParameterList = $ParameterList
+            [pscustomobject]@{ MockHandle = $true }
+        }
+        Mock Write-WinUtilLog { }
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name AppTitle -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name capturedUninstallScriptBlock -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name capturedUninstallParameterList -Scope Script -ErrorAction SilentlyContinue
+    }
+
+    It "confirms and queues selected packages with the configured package manager preference" {
+        Invoke-WPFUnInstall -PackagesToUninstall @($script:package)
+
+        Should -Invoke -CommandName Show-WinUtilMessage -Times 1 -Exactly -ParameterFilter {
+            $Message -like "*This will uninstall the following applications:*" -and
+                $Message -like "*Git*" -and
+                $Title -eq "Are you sure?" -and
+                "$Button" -eq "YesNo" -and
+                "$Icon" -eq "Information"
+        }
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 1 -Exactly -ParameterFilter {
+            $ScriptBlock -is [scriptblock] -and
+                $ParameterList.Count -eq 2 -and
+                $ParameterList[0][0] -eq "PackagesToUninstall" -and
+                @($ParameterList[0][1]).Count -eq 1 -and
+                @($ParameterList[0][1])[0].winget -eq "Git.Git" -and
+                $ParameterList[1][0] -eq "ManagerPreference" -and
+                $ParameterList[1][1] -eq [PackageManagers]::Winget
+        }
+        Should -Invoke -CommandName Write-WinUtilLog -Times 1 -Exactly -ParameterFilter {
+            $Component -eq "Uninstall" -and
+                $Message -eq "Uninstall selected package(s): Git (winget: Git.Git)"
+        }
+    }
+
+    It "prompts and exits when no packages are selected" {
+        Invoke-WPFUnInstall -PackagesToUninstall @()
+
+        Should -Invoke -CommandName Show-WinUtilMessage -Times 1 -Exactly -ParameterFilter {
+            $Message -eq "Please select the program(s) to uninstall" -and
+                $Title -eq "Winutil" -and
+                $Button -eq "OK" -and
+                $Icon -eq "Warning"
+        }
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 0 -Exactly
+    }
+
+    It "prompts and exits when another install process is running" {
+        $script:sync.ProcessRunning = $true
+
+        Invoke-WPFUnInstall -PackagesToUninstall @($script:package)
+
+        Should -Invoke -CommandName Show-WinUtilMessage -Times 1 -Exactly -ParameterFilter {
+            $Message -eq "[Invoke-WPFUnInstall] Install process is currently running" -and
+                $Title -eq "Winutil" -and
+                $Button -eq "OK" -and
+                $Icon -eq "Warning"
+        }
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 0 -Exactly
+    }
+
+    It "exits without queueing uninstall when confirmation is declined" {
+        Mock Show-WinUtilMessage { "No" } -ParameterFilter { $Title -eq "Are you sure?" }
+
+        Invoke-WPFUnInstall -PackagesToUninstall @($script:package)
+
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 0 -Exactly
+    }
+}
+
+Describe "Invoke-WPFUnInstall runspace body" {
+    BeforeEach {
+        $script:package = New-WinUtilPackage
+        New-WinUtilInstallTestContext -Packages @($script:package)
+        $script:capturedUninstallScriptBlock = $null
+
+        Mock Show-WinUtilMessage { "Yes" }
+        Mock Invoke-WPFRunspace {
+            $script:capturedUninstallScriptBlock = $ScriptBlock
+            [pscustomobject]@{ MockHandle = $true }
+        }
+        Mock Get-WinUtilSelectedPackages {
+            New-WinUtilPackageSplit -Winget @("Git.Git") -Choco @("vlc")
+        }
+        Mock Show-WPFInstallAppBusy { }
+        Mock Hide-WPFInstallAppBusy { }
+        Mock Install-WinUtilProgramWinget { }
+        Mock Install-WinUtilProgramChoco { }
+        Mock Invoke-WPFUIThread { }
+        Mock Write-WinUtilLog { }
+        Mock Write-Host { }
+        Mock New-Item { }
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name AppTitle -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name capturedUninstallScriptBlock -Scope Script -ErrorAction SilentlyContinue
+    }
+
+    It "uninstalls split winget and choco packages and cleans up on success" {
+        Invoke-WPFUnInstall -PackagesToUninstall @($script:package)
+
+        & $script:capturedUninstallScriptBlock -PackagesToUninstall @($script:package) -ManagerPreference ([PackageManagers]::Winget)
+
+        Should -Invoke -CommandName Get-WinUtilSelectedPackages -Times 1 -Exactly -ParameterFilter {
+            @($PackageList).Count -eq 1 -and $Preference -eq [PackageManagers]::Winget
+        }
+        Should -Invoke -CommandName Show-WPFInstallAppBusy -Times 1 -Exactly -ParameterFilter {
+            $text -eq "Uninstalling apps..."
+        }
+        Should -Invoke -CommandName Install-WinUtilProgramWinget -Times 1 -Exactly -ParameterFilter {
+            $Action -eq "Uninstall" -and @($Programs)[0] -eq "Git.Git"
+        }
+        Should -Invoke -CommandName Install-WinUtilProgramChoco -Times 1 -Exactly -ParameterFilter {
+            $Action -eq "Uninstall" -and @($Programs)[0] -eq "vlc"
+        }
+        Should -Invoke -CommandName Hide-WPFInstallAppBusy -Times 1 -Exactly
+        Should -Invoke -CommandName Invoke-WPFUIThread -Times 1 -Exactly -ParameterFilter {
+            $ScriptBlock.ToString() -like '*Set-WinUtilTaskbaritem -state "None" -overlay "checkmark"*'
+        }
+        $script:sync.ProcessRunning | Should -BeFalse
+    }
+
+    It "hides the busy overlay, sets taskbar error state, and clears ProcessRunning on failure" {
+        Mock Install-WinUtilProgramWinget { throw "winget failed" }
+
+        Invoke-WPFUnInstall -PackagesToUninstall @($script:package)
+
+        & $script:capturedUninstallScriptBlock -PackagesToUninstall @($script:package) -ManagerPreference ([PackageManagers]::Winget)
+
+        Should -Invoke -CommandName Hide-WPFInstallAppBusy -Times 1 -Exactly
+        Should -Invoke -CommandName Invoke-WPFUIThread -Times 1 -Exactly -ParameterFilter {
+            $ScriptBlock.ToString() -like '*Set-WinUtilTaskbaritem -state "Error" -overlay "warning"*'
+        }
+        Should -Invoke -CommandName Write-WinUtilLog -Times 1 -Exactly -ParameterFilter {
+            $Level -eq "ERROR" -and $Component -eq "Uninstall" -and $Message -like "Uninstall workflow failed:*"
+        }
+        $script:sync.ProcessRunning | Should -BeFalse
+    }
+}
diff --git a/pester/logging.Tests.ps1 b/pester/logging.Tests.ps1
new file mode 100644
index 00000000..79c3d745
--- /dev/null
+++ b/pester/logging.Tests.ps1
@@ -0,0 +1,107 @@
+#===========================================================================
+# Tests - WinUtil Logging
+#===========================================================================
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+
+    . (Join-Path $script:repoRoot "functions\private\Write-WinUtilLog.ps1")
+}
+
+Describe "Write-WinUtilLog" {
+    BeforeEach {
+        $script:testRoot = Join-Path ([System.IO.Path]::GetTempPath()) "winutil-logging-$([guid]::NewGuid())"
+        New-Item -Path $script:testRoot -ItemType Directory -Force | Out-Null
+        Remove-Variable -Name WinUtilLogPath -Scope Script -ErrorAction SilentlyContinue
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name WinUtilLogPath -Scope Script -ErrorAction SilentlyContinue
+        Remove-Item -Path $script:testRoot -Recurse -Force -ErrorAction SilentlyContinue
+    }
+
+    It "writes to the active timestamped session log under logs" {
+        $logPath = Join-Path $script:testRoot "logs\winutil_2026-07-01_12-00-00.log"
+        $script:sync = [hashtable]::Synchronized(@{
+            winutildir = $script:testRoot
+            logPath = $logPath
+        })
+
+        Write-WinUtilLog -Component "Test" -Message "same session log"
+
+        Test-Path -Path $logPath | Should -BeTrue
+        Test-Path -Path (Join-Path $script:testRoot "winutil.log") | Should -BeFalse
+        Get-Content -Path $logPath -Raw | Should -Match "\[INFO\] \[Test\] same session log"
+    }
+
+    It "uses the transcript stream when logPath is not set" {
+        $transcriptPath = Join-Path $script:testRoot "logs\winutil_2026-07-01_12-00-00.log"
+        $script:sync = [hashtable]::Synchronized(@{
+            winutildir = $script:testRoot
+            transcriptPath = $transcriptPath
+        })
+        Mock Add-Content { }
+        Mock Write-Host { }
+
+        Write-WinUtilLog -Component "Test" -Message "transcript fallback"
+
+        Should -Invoke -CommandName Add-Content -Times 0 -Exactly
+        Should -Invoke -CommandName Write-Host -Times 1 -Exactly -ParameterFilter {
+            $Object -match "\[INFO\] \[Test\] transcript fallback"
+        }
+        Test-Path -Path (Join-Path $script:testRoot "winutil.log") | Should -BeFalse
+    }
+
+    It "creates one fallback log under logs when only winutildir is available" {
+        $script:sync = [hashtable]::Synchronized(@{
+            winutildir = $script:testRoot
+        })
+
+        Write-WinUtilLog -Component "Test" -Message "first fallback entry"
+        Write-WinUtilLog -Component "Test" -Message "second fallback entry"
+
+        $logFiles = @(Get-ChildItem -Path (Join-Path $script:testRoot "logs") -Filter "winutil_*.log")
+        $logFiles.Count | Should -Be 1
+        Test-Path -Path (Join-Path $script:testRoot "winutil.log") | Should -BeFalse
+
+        $content = Get-Content -Path $logFiles[0].FullName -Raw
+        $content | Should -Match "first fallback entry"
+        $content | Should -Match "second fallback entry"
+    }
+
+    It "does not append directly when the active log file is the transcript" {
+        $logPath = Join-Path $script:testRoot "logs\winutil_2026-07-01_12-00-00.log"
+        $script:sync = [hashtable]::Synchronized(@{
+            winutildir = $script:testRoot
+            logPath = $logPath
+            transcriptPath = $logPath
+        })
+
+        Mock Add-Content { throw [System.IO.IOException]::new("locked by transcript") } -ParameterFilter {
+            $Path -eq $logPath -and $ErrorAction -eq "Stop"
+        }
+        Mock Write-Host { }
+        Mock Write-Warning { }
+
+        Write-WinUtilLog -Component "Test" -Message "transcript stream fallback"
+
+        Should -Invoke -CommandName Add-Content -Times 0 -Exactly
+        Should -Invoke -CommandName Write-Host -Times 1 -Exactly -ParameterFilter {
+            $Object -match "\[INFO\] \[Test\] transcript stream fallback"
+        }
+        Should -Invoke -CommandName Write-Warning -Times 0 -Exactly
+    }
+
+}
+
+Describe "WinUtil startup logging path" {
+    It "uses one timestamped log file under the logs directory" {
+        $startScript = Get-Content -Path (Join-Path $script:repoRoot "scripts\start.ps1") -Raw
+
+        $startScript | Should -Match '\$sync\.logPath = "\$logdir\\winutil_\$dateTime\.log"'
+        $startScript | Should -Match '\$sync\.transcriptPath = \$sync\.logPath'
+        $startScript | Should -Match 'Start-Transcript -Path \$sync\.logPath'
+        $startScript | Should -Not -Match '\$sync\.logPath = "\$winutildir\\winutil\.log"'
+    }
+}
diff --git a/pester/package.Tests.ps1 b/pester/package.Tests.ps1
new file mode 100644
index 00000000..e5a0e468
--- /dev/null
+++ b/pester/package.Tests.ps1
@@ -0,0 +1,181 @@
+#===========================================================================
+# Tests - Package Selection and Package Managers
+#===========================================================================
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+
+    if (-not ("PackageManagers" -as [type])) {
+        Add-Type @"
+public enum PackageManagers
+{
+    Winget,
+    Choco
+}
+"@
+    }
+
+    . (Join-Path $script:repoRoot "functions\private\Get-WinUtilSelectedPackages.ps1")
+    . (Join-Path $script:repoRoot "functions\private\Test-WinUtilPackageManager.ps1")
+    . (Join-Path $script:repoRoot "functions\private\Install-WinUtilProgramWinget.ps1")
+    . (Join-Path $script:repoRoot "functions\private\Install-WinUtilProgramChoco.ps1")
+
+    function Invoke-WPFUIThread { }
+    function Write-WinUtilLog { }
+}
+
+Describe "Get-WinUtilSelectedPackages" {
+    BeforeEach {
+        Mock Invoke-WPFUIThread { }
+    }
+
+    It "uses winget IDs when winget is preferred" {
+        $packages = @(
+            [pscustomobject]@{ winget = "Git.Git"; choco = "git" }
+            [pscustomobject]@{ winget = "VideoLAN.VLC"; choco = "vlc" }
+        )
+
+        $result = Get-WinUtilSelectedPackages -PackageList $packages -Preference ([PackageManagers]::Winget)
+
+        (@($result[[PackageManagers]::Winget]) -join "|") | Should -Be "Git.Git|VideoLAN.VLC"
+        @($result[[PackageManagers]::Choco]).Count | Should -Be 0
+    }
+
+    It "uses choco IDs and falls back to winget for na or missing choco IDs" {
+        $packages = @(
+            [pscustomobject]@{ winget = "Git.Git"; choco = "git" }
+            [pscustomobject]@{ winget = "VideoLAN.VLC"; choco = "na" }
+            [pscustomobject]@{ winget = "Mozilla.Firefox" }
+        )
+
+        $result = Get-WinUtilSelectedPackages -PackageList $packages -Preference ([PackageManagers]::Choco)
+
+        (@($result[[PackageManagers]::Choco]) -join "|") | Should -Be "git"
+        (@($result[[PackageManagers]::Winget]) -join "|") | Should -Be "VideoLAN.VLC|Mozilla.Firefox"
+    }
+
+    It "skips blank, na, and missing package IDs" {
+        $packages = @(
+            [pscustomobject]@{ winget = ""; choco = "" }
+            [pscustomobject]@{ winget = "na"; choco = "na" }
+            [pscustomobject]@{ choco = "only-choco" }
+            [pscustomobject]@{ winget = "   " }
+        )
+
+        $result = Get-WinUtilSelectedPackages -PackageList $packages -Preference ([PackageManagers]::Winget)
+
+        @($result[[PackageManagers]::Winget]).Count | Should -Be 0
+        @($result[[PackageManagers]::Choco]).Count | Should -Be 0
+    }
+
+    It "deduplicates package IDs" {
+        $packages = @(
+            [pscustomobject]@{ winget = "Git.Git"; choco = "git" }
+            [pscustomobject]@{ winget = "Git.Git"; choco = "git" }
+            [pscustomobject]@{ winget = "VideoLAN.VLC"; choco = "vlc" }
+        )
+
+        $result = Get-WinUtilSelectedPackages -PackageList $packages -Preference ([PackageManagers]::Choco)
+
+        (@($result[[PackageManagers]::Choco]) -join "|") | Should -Be "git|vlc"
+        @($result[[PackageManagers]::Winget]).Count | Should -Be 0
+    }
+
+    It "returns empty package lists for an empty selection" {
+        $result = Get-WinUtilSelectedPackages -PackageList @() -Preference ([PackageManagers]::Winget)
+
+        @($result[[PackageManagers]::Winget]).Count | Should -Be 0
+        @($result[[PackageManagers]::Choco]).Count | Should -Be 0
+    }
+}
+
+Describe "Test-WinUtilPackageManager" {
+    BeforeEach {
+        Mock Write-Host { }
+    }
+
+    It "reports winget installed when the command exists" {
+        Mock Get-Command {
+            [pscustomobject]@{ Name = "winget" }
+        } -ParameterFilter { $Name -eq "winget" -and $ErrorAction -eq "SilentlyContinue" }
+
+        Test-WinUtilPackageManager -winget | Should -Be "installed"
+
+        Should -Invoke -CommandName Get-Command -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "winget" -and $ErrorAction -eq "SilentlyContinue"
+        }
+    }
+
+    It "reports choco not installed when the command is missing" {
+        Mock Get-Command {
+            $null
+        } -ParameterFilter { $Name -eq "choco" -and $ErrorAction -eq "SilentlyContinue" }
+
+        Test-WinUtilPackageManager -choco | Should -Be "not-installed"
+
+        Should -Invoke -CommandName Get-Command -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "choco" -and $ErrorAction -eq "SilentlyContinue"
+        }
+    }
+}
+
+Describe "Install-WinUtilProgramWinget" {
+    BeforeEach {
+        Mock Write-WinUtilLog { }
+        Mock Start-Process { [pscustomobject]@{ ExitCode = 0 } }
+    }
+
+    It "starts winget with install arguments" {
+        Install-WinUtilProgramWinget -Action Install -Programs @("Git.Git")
+
+        Should -Invoke -CommandName Start-Process -Times 1 -Exactly -ParameterFilter {
+            $FilePath -eq "winget" -and
+                (@($ArgumentList) -join "|") -eq "install|--id|Git.Git|--accept-package-agreements|--accept-source-agreements|--source|winget|--silent" -and
+                $NoNewWindow -eq $true -and
+                $Wait -eq $true -and
+                $PassThru -eq $true
+        }
+    }
+
+    It "starts winget with uninstall arguments and msstore source when requested" {
+        Install-WinUtilProgramWinget -Action Uninstall -Programs @("msstore:9NBLGGH4NNS1")
+
+        Should -Invoke -CommandName Start-Process -Times 1 -Exactly -ParameterFilter {
+            $FilePath -eq "winget" -and
+                (@($ArgumentList) -join "|") -eq "uninstall|--id|9NBLGGH4NNS1|--source|msstore|--silent"
+        }
+    }
+
+    It "skips whitespace and na package IDs" {
+        Install-WinUtilProgramWinget -Action Install -Programs @(" ", "na")
+
+        Should -Invoke -CommandName Start-Process -Times 0 -Exactly
+    }
+}
+
+Describe "Install-WinUtilProgramChoco" {
+    BeforeEach {
+        Mock Write-WinUtilLog { }
+        Mock Start-Process { [pscustomobject]@{ ExitCode = 0 } }
+    }
+
+    It "starts choco with install arguments" {
+        Install-WinUtilProgramChoco -Action Install -Programs @("git", "vlc")
+
+        Should -Invoke -CommandName Start-Process -Times 1 -Exactly -ParameterFilter {
+            $FilePath -eq "choco" -and
+                $ArgumentList -eq "install git vlc -y" -and
+                $NoNewWindow -eq $true -and
+                $Wait -eq $true -and
+                $PassThru -eq $true
+        }
+    }
+
+    It "starts choco with uninstall arguments" {
+        Install-WinUtilProgramChoco -Action Uninstall -Programs @("git")
+
+        Should -Invoke -CommandName Start-Process -Times 1 -Exactly -ParameterFilter {
+            $FilePath -eq "choco" -and $ArgumentList -eq "uninstall git -y"
+        }
+    }
+}
diff --git a/pester/preferences-theme.Tests.ps1 b/pester/preferences-theme.Tests.ps1
new file mode 100644
index 00000000..c65eba3e
--- /dev/null
+++ b/pester/preferences-theme.Tests.ps1
@@ -0,0 +1,347 @@
+#===========================================================================
+# Tests - Preferences and Themes
+#===========================================================================
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+
+    if (-not ("PackageManagers" -as [type])) {
+        Add-Type @"
+public enum PackageManagers
+{
+    Winget,
+    Choco
+}
+"@
+    }
+
+    if (-not ("Windows.Media.SolidColorBrush" -as [type])) {
+        Add-Type @"
+namespace Windows.Media
+{
+    public class SolidColorBrush
+    {
+        public object Value { get; private set; }
+
+        public SolidColorBrush(object value)
+        {
+            Value = value;
+        }
+
+        public override string ToString()
+        {
+            return Value == null ? "" : Value.ToString();
+        }
+    }
+
+    public struct Color
+    {
+        public byte R;
+        public byte G;
+        public byte B;
+
+        public static Color FromRgb(byte r, byte g, byte b)
+        {
+            return new Color { R = r, G = g, B = b };
+        }
+
+        public override string ToString()
+        {
+            return string.Format("#{0:X2}{1:X2}{2:X2}", R, G, B);
+        }
+    }
+
+    public class FontFamily
+    {
+        public string Value { get; private set; }
+
+        public FontFamily(string value)
+        {
+            Value = value;
+        }
+
+        public override string ToString()
+        {
+            return Value;
+        }
+    }
+}
+
+namespace System.Windows
+{
+    public class CornerRadius
+    {
+        public double Value { get; private set; }
+
+        public CornerRadius(double value)
+        {
+            Value = value;
+        }
+
+        public override string ToString()
+        {
+            return Value.ToString();
+        }
+    }
+
+    public class GridLength
+    {
+        public double Value { get; private set; }
+
+        public GridLength(double value)
+        {
+            Value = value;
+        }
+
+        public override string ToString()
+        {
+            return Value.ToString();
+        }
+    }
+
+    public class Thickness
+    {
+        public double Left { get; private set; }
+        public double Top { get; private set; }
+        public double Right { get; private set; }
+        public double Bottom { get; private set; }
+
+        public Thickness(double uniformLength)
+        {
+            Left = uniformLength;
+            Top = uniformLength;
+            Right = uniformLength;
+            Bottom = uniformLength;
+        }
+
+        public Thickness(double horizontal, double vertical)
+        {
+            Left = horizontal;
+            Top = vertical;
+            Right = horizontal;
+            Bottom = vertical;
+        }
+
+        public Thickness(double left, double top, double right, double bottom)
+        {
+            Left = left;
+            Top = top;
+            Right = right;
+            Bottom = bottom;
+        }
+
+        public override string ToString()
+        {
+            return string.Format("{0},{1},{2},{3}", Left, Top, Right, Bottom);
+        }
+    }
+}
+"@
+    }
+
+    . (Join-Path $script:repoRoot "functions\private\Set-Preferences.ps1")
+    . (Join-Path $script:repoRoot "functions\private\Invoke-WinutilThemeChange.ps1")
+
+    function Get-WinUtilToggleStatus {
+        param($ToggleName)
+        return $false
+    }
+
+    function script:New-WinUtilPreferencesTestRoot {
+        $testRoot = Join-Path ([IO.Path]::GetTempPath()) "WinUtilPreferences_$([guid]::NewGuid())"
+        New-Item -Path $testRoot -ItemType Directory -Force | Out-Null
+        $testRoot
+    }
+
+    function script:New-WinUtilFakeThemeForm {
+        $themeButton = [pscustomobject]@{
+            Content = $null
+        }
+
+        $form = [pscustomobject]@{
+            Resources = @{}
+            ThemeButton = $themeButton
+        }
+        $form | Add-Member -MemberType ScriptMethod -Name FindName -Value {
+            param($name)
+
+            if ($name -eq "ThemeButton") {
+                return $this.ThemeButton
+            }
+
+            return $null
+        }
+
+        $form
+    }
+
+    function script:New-WinUtilPreferenceSync {
+        param(
+            [hashtable]$Preferences = @{}
+        )
+
+        $script:sync = [Hashtable]::Synchronized(@{
+            preferences = $Preferences
+            configs = @{
+                themes = Get-Content -Path (Join-Path $script:repoRoot "config\themes.json") -Raw | ConvertFrom-Json
+            }
+            Form = New-WinUtilFakeThemeForm
+        })
+        $global:sync = $script:sync
+    }
+
+    function script:Remove-WinUtilPreferenceGlobals {
+        Remove-Variable -Name sync -Scope Global -ErrorAction SilentlyContinue
+        Remove-Variable -Name winutildir -Scope Global -ErrorAction SilentlyContinue
+    }
+}
+
+Describe "Set-Preferences" {
+    AfterEach {
+        if ($script:testRoot -and (Test-Path $script:testRoot)) {
+            Remove-Item -Path $script:testRoot -Recurse -Force -ErrorAction SilentlyContinue
+        }
+        $script:testRoot = $null
+        Remove-WinUtilPreferenceGlobals
+    }
+
+    It "loads default preferences when no preferences file exists" {
+        $script:testRoot = New-WinUtilPreferencesTestRoot
+        $global:winutildir = $script:testRoot
+        New-WinUtilPreferenceSync
+
+        Set-Preferences
+
+        $script:sync.preferences.theme | Should -Be "Auto"
+        $script:sync.preferences.packagemanager | Should -Be ([PackageManagers]::Winget)
+    }
+
+    It "loads saved preferences and converts the package manager to an enum" {
+        $script:testRoot = New-WinUtilPreferencesTestRoot
+        $global:winutildir = $script:testRoot
+        New-WinUtilPreferenceSync
+        Set-Content -Path (Join-Path $script:testRoot "preferences.ini") -Value @(
+            "theme = Dark"
+            "packagemanager = Choco"
+        )
+
+        Set-Preferences
+
+        $script:sync.preferences.theme | Should -Be "Dark"
+        $script:sync.preferences.packagemanager | Should -Be ([PackageManagers]::Choco)
+    }
+
+    It "saves current preferences to preferences.ini" {
+        $script:testRoot = New-WinUtilPreferencesTestRoot
+        $global:winutildir = $script:testRoot
+        New-WinUtilPreferenceSync -Preferences @{
+            theme = "Light"
+            packagemanager = [PackageManagers]::Winget
+        }
+
+        Set-Preferences -save
+
+        $preferencesText = Get-Content -Path (Join-Path $script:testRoot "preferences.ini") -Raw
+        $preferencesText | Should -Match "theme=Light"
+        $preferencesText | Should -Match "packagemanager=Winget"
+    }
+
+    It "absorbs legacy preference files and removes old markers" {
+        $script:testRoot = New-WinUtilPreferencesTestRoot
+        $global:winutildir = $script:testRoot
+        New-WinUtilPreferenceSync
+        Set-Content -Path (Join-Path $script:testRoot "LightTheme.ini") -Value ""
+        Set-Content -Path (Join-Path $script:testRoot "preferChocolatey.ini") -Value ""
+
+        Set-Preferences
+
+        $script:sync.preferences.theme | Should -Be "Light"
+        $script:sync.preferences.packagemanager | Should -Be ([PackageManagers]::Choco)
+        Test-Path (Join-Path $script:testRoot "LightTheme.ini") | Should -BeFalse
+        Test-Path (Join-Path $script:testRoot "preferChocolatey.ini") | Should -BeFalse
+    }
+
+    It "absorbs old package manager preferences stored without a key" {
+        $script:testRoot = New-WinUtilPreferencesTestRoot
+        $global:winutildir = $script:testRoot
+        New-WinUtilPreferenceSync
+        Set-Content -Path (Join-Path $script:testRoot "preferences.ini") -Value "Choco"
+
+        Set-Preferences
+
+        $script:sync.preferences.theme | Should -Be "Auto"
+        $script:sync.preferences.packagemanager | Should -Be ([PackageManagers]::Choco)
+    }
+}
+
+Describe "Invoke-WinutilThemeChange" {
+    AfterEach {
+        if ($script:testRoot -and (Test-Path $script:testRoot)) {
+            Remove-Item -Path $script:testRoot -Recurse -Force -ErrorAction SilentlyContinue
+        }
+        $script:testRoot = $null
+        Remove-WinUtilPreferenceGlobals
+    }
+
+    It "applies shared and selected theme resources, saves the preference, and updates the theme button" {
+        $script:testRoot = New-WinUtilPreferencesTestRoot
+        $global:winutildir = $script:testRoot
+        New-WinUtilPreferenceSync
+
+        Invoke-WinutilThemeChange -theme "Dark"
+
+        $script:sync.preferences.theme | Should -Be "Dark"
+        $script:sync.Form.Resources.ContainsKey("FontFamily") | Should -BeTrue
+        $script:sync.Form.Resources.ContainsKey("ButtonCornerRadius") | Should -BeTrue
+        $script:sync.Form.Resources.ContainsKey("MainBackgroundColor") | Should -BeTrue
+        $script:sync.Form.Resources.ContainsKey("CBorderColor") | Should -BeTrue
+        $script:sync.Form.ThemeButton.Content | Should -Be ([string][char]0xE708)
+
+        $preferencesText = Get-Content -Path (Join-Path $script:testRoot "preferences.ini") -Raw
+        $preferencesText | Should -Match "theme=Dark"
+    }
+
+    It "uses the system dark-mode toggle when Auto theme is selected" {
+        $script:testRoot = New-WinUtilPreferencesTestRoot
+        $global:winutildir = $script:testRoot
+        New-WinUtilPreferenceSync
+        Mock Get-WinUtilToggleStatus { return $true }
+
+        Invoke-WinutilThemeChange -theme "Auto"
+
+        Should -Invoke -CommandName Get-WinUtilToggleStatus -Times 1 -Exactly -ParameterFilter {
+            $ToggleName -eq "WPFToggleDarkMode"
+        }
+        $script:sync.preferences.theme | Should -Be "Auto"
+        $script:sync.Form.Resources.ContainsKey("MainBackgroundColor") | Should -BeTrue
+        $script:sync.Form.ThemeButton.Content | Should -Be ([string][char]0xF08C)
+    }
+}
+
+Describe "Theme configuration" {
+    It "contains resources with value shapes consumed by theme application" {
+        $themes = Get-Content -Path (Join-Path $script:repoRoot "config\themes.json") -Raw | ConvertFrom-Json
+        $invalidEntries = [System.Collections.Generic.List[string]]::new()
+
+        foreach ($themeName in @("shared", "Light", "Dark")) {
+            foreach ($property in $themes.$themeName.PSObject.Properties) {
+                if ($property.Name -like "*Color" -and [string]$property.Value -notmatch '^(#[0-9A-Fa-f]{6}|Transparent)$') {
+                    $invalidEntries.Add("$themeName.$($property.Name) should be a hex color or Transparent")
+                }
+                elseif ($property.Name -like "*Radius" -and [string]$property.Value -notmatch '^\d+(\.\d+)?$') {
+                    $invalidEntries.Add("$themeName.$($property.Name) should be numeric")
+                }
+                elseif (($property.Name -like "*Thickness" -or $property.Name -like "*Margin") -and [string]$property.Value -notmatch '^\d+(\.\d+)?(,\d+(\.\d+)?){0,3}$') {
+                    $invalidEntries.Add("$themeName.$($property.Name) should be one, two, or four numeric values")
+                }
+                elseif ($property.Name -like "*RowHeight*" -and [string]$property.Value -notmatch '^\d+(\.\d+)?$') {
+                    $invalidEntries.Add("$themeName.$($property.Name) should be numeric")
+                }
+            }
+        }
+
+        if ($invalidEntries.Count -gt 0) {
+            throw ($invalidEntries -join "`n")
+        }
+    }
+}
diff --git a/pester/runspace.Tests.ps1 b/pester/runspace.Tests.ps1
new file mode 100644
index 00000000..9cb42e85
--- /dev/null
+++ b/pester/runspace.Tests.ps1
@@ -0,0 +1,168 @@
+#===========================================================================
+# Tests - Runspace Behavior
+#===========================================================================
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFRunspace.ps1")
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFFeatureInstall.ps1")
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFAppxRemoval.ps1")
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFundoall.ps1")
+
+    function script:New-WinUtilRunspaceTestContext {
+        param([hashtable]$InitialSync = @{})
+
+        $script:sync = [Hashtable]::Synchronized($InitialSync)
+        $initialSessionState = [System.Management.Automation.Runspaces.InitialSessionState]::CreateDefault()
+        $syncVariable = New-Object System.Management.Automation.Runspaces.SessionStateVariableEntry -ArgumentList "sync", $script:sync, $null
+        $initialSessionState.Variables.Add($syncVariable)
+        $script:sync.runspace = [runspacefactory]::CreateRunspacePool(1, 2, $initialSessionState, $Host)
+        $script:sync.runspace.Open()
+    }
+
+    function script:Clear-WinUtilRunspaceTestContext {
+        if ($script:powershell) {
+            $script:powershell.Dispose()
+        }
+
+        if ($script:sync -and $script:sync.runspace) {
+            $script:sync.runspace.Close()
+            $script:sync.runspace.Dispose()
+        }
+
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name powershell -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name handle -Scope Script -ErrorAction SilentlyContinue
+    }
+
+    function script:Assert-WinUtilAsyncHandle {
+        param($Handle)
+
+        ($Handle -is [System.IAsyncResult]) | Should -BeTrue
+        ($Handle -is [array]) | Should -BeFalse
+        $Handle.AsyncWaitHandle.WaitOne(5000) | Should -BeTrue
+    }
+}
+
+Describe "Invoke-WPFRunspace behavior" {
+    BeforeEach {
+        New-WinUtilRunspaceTestContext -InitialSync @{ Marker = "shared" }
+    }
+
+    AfterEach {
+        Clear-WinUtilRunspaceTestContext
+    }
+
+    It "returns a single async handle with no argument list" {
+        $handle = Invoke-WPFRunspace -ScriptBlock {
+            Start-Sleep -Milliseconds 100
+            "no-args|$($sync.Marker)"
+        }
+
+        Assert-WinUtilAsyncHandle -Handle $handle
+        @($script:powershell.EndInvoke($handle))[0] | Should -Be "no-args|shared"
+    }
+
+    It "passes one named parameter" {
+        $handle = Invoke-WPFRunspace -ParameterList @(,("Name", "value")) -ScriptBlock {
+            param([string]$Name)
+
+            Start-Sleep -Milliseconds 100
+            "Name=$Name"
+        }
+
+        Assert-WinUtilAsyncHandle -Handle $handle
+        @($script:powershell.EndInvoke($handle))[0] | Should -Be "Name=value"
+    }
+
+    It "passes multiple named parameters" {
+        $handle = Invoke-WPFRunspace -ParameterList @(
+            ("First", "alpha"),
+            ("Second", "beta")
+        ) -ScriptBlock {
+            param(
+                [string]$First,
+                [string]$Second
+            )
+
+            Start-Sleep -Milliseconds 100
+            "$First|$Second|$($sync.Marker)"
+        }
+
+        Assert-WinUtilAsyncHandle -Handle $handle
+        @($script:powershell.EndInvoke($handle))[0] | Should -Be "alpha|beta|shared"
+    }
+
+    It "surfaces scriptblock failures through the owning PowerShell instance" {
+        $handle = Invoke-WPFRunspace -ScriptBlock {
+            Start-Sleep -Milliseconds 100
+            throw "runspace failure"
+        }
+
+        Assert-WinUtilAsyncHandle -Handle $handle
+        { $script:powershell.EndInvoke($handle) } | Should -Throw -ExpectedMessage "*runspace failure*"
+    }
+}
+
+Describe "Public runspace callers" {
+    BeforeEach {
+        $script:sync = [Hashtable]::Synchronized(@{
+            ProcessRunning = $false
+            selectedFeatures = [System.Collections.Generic.List[string]]::new()
+            selectedTweaks = [System.Collections.Generic.List[string]]::new()
+            selectedAppx = [System.Collections.Generic.List[string]]::new()
+            configs = @{
+                appxHashtable = @{}
+            }
+        })
+
+        Mock Invoke-WPFRunspace { [pscustomobject]@{ MockHandle = $true } }
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+    }
+
+    It "queues selected feature installation without executing the runspace body" {
+        $script:sync.selectedFeatures.Add("WPFFeaturesSandbox")
+
+        Invoke-WPFFeatureInstall
+
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 1 -Exactly -ParameterFilter {
+            $ScriptBlock -is [scriptblock] -and $null -eq $ArgumentList -and $null -eq $ParameterList
+        }
+    }
+
+    It "passes selected tweaks as the runspace argument list for undo all" {
+        $script:sync.selectedTweaks.Add("WPFTweaksTelemetry")
+        $script:sync.selectedTweaks.Add("WPFTweaksServices")
+
+        Invoke-WPFundoall
+
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 1 -Exactly -ParameterFilter {
+            $ScriptBlock -is [scriptblock] -and
+                $ArgumentList.Count -eq 2 -and
+                $ArgumentList[0] -eq "WPFTweaksTelemetry" -and
+                $ArgumentList[1] -eq "WPFTweaksServices"
+        }
+    }
+
+    It "passes selected AppX items and app metadata to the removal runspace" {
+        $script:sync.selectedAppx.Add("WPFAppxExample")
+        $script:sync.configs.appxHashtable["WPFAppxExample"] = [pscustomobject]@{
+            Content = "Example"
+            PackageId = "Example.Package"
+        }
+
+        Invoke-WPFAppxRemoval
+
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 1 -Exactly -ParameterFilter {
+            $ScriptBlock -is [scriptblock] -and
+                $ParameterList.Count -eq 2 -and
+                $ParameterList[0][0] -eq "selected" -and
+                $ParameterList[0][1][0] -eq "WPFAppxExample" -and
+                $ParameterList[1][0] -eq "apps" -and
+                $ParameterList[1][1].ContainsKey("WPFAppxExample")
+        }
+    }
+}
diff --git a/pester/sanity.Tests.ps1 b/pester/sanity.Tests.ps1
new file mode 100644
index 00000000..91c62aa8
--- /dev/null
+++ b/pester/sanity.Tests.ps1
@@ -0,0 +1,259 @@
+#===========================================================================
+# Tests - General Sanity
+#===========================================================================
+
+$repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+
+    function script:Test-WinUtilParser {
+        param([string]$Path)
+
+        $tokens = $null
+        $syntaxErrors = $null
+        [System.Management.Automation.Language.Parser]::ParseFile($Path, [ref]$tokens, [ref]$syntaxErrors) | Out-Null
+
+        if ($syntaxErrors.Count -ne 0) {
+            throw ($syntaxErrors | Out-String)
+        }
+    }
+
+    function script:Invoke-WindowsPowerShellParser {
+        param([string[]]$Path)
+
+        $windowsPowerShell = Get-Command powershell.exe -ErrorAction SilentlyContinue
+        if (-not $windowsPowerShell) {
+            Set-ItResult -Skipped -Because "powershell.exe is not available on this platform."
+            return
+        }
+
+        $previousPaths = $env:WINUTIL_TEST_PARSE_PATHS
+        try {
+            $env:WINUTIL_TEST_PARSE_PATHS = @($Path) -join [Environment]::NewLine
+            $parseScript = @'
+$ErrorActionPreference = 'Stop'
+$paths = $env:WINUTIL_TEST_PARSE_PATHS -split "`r?`n" | Where-Object { $_ }
+$failed = @()
+
+foreach ($path in $paths) {
+    $tokens = $null
+    $syntaxErrors = $null
+    [System.Management.Automation.Language.Parser]::ParseFile($path, [ref]$tokens, [ref]$syntaxErrors) | Out-Null
+
+    if ($syntaxErrors.Count -ne 0) {
+        $messages = $syntaxErrors | ForEach-Object { $_.Message }
+        $failed += "[$path] $($messages -join '; ')"
+    }
+}
+
+if ($failed.Count -gt 0) {
+    $failed -join [Environment]::NewLine
+    exit 1
+}
+'@
+
+            $output = & $windowsPowerShell.Source -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command $parseScript 2>&1
+            if ($LASTEXITCODE -ne 0) {
+                throw "Windows PowerShell parser failed:`n$($output | Out-String)"
+            }
+        } finally {
+            if ($null -eq $previousPaths) {
+                Remove-Item Env:\WINUTIL_TEST_PARSE_PATHS -ErrorAction SilentlyContinue
+            } else {
+                $env:WINUTIL_TEST_PARSE_PATHS = $previousPaths
+            }
+        }
+    }
+}
+
+Describe "PowerShell source sanity" {
+    $scriptCases = @(
+        "Compile.ps1",
+        "windev.ps1",
+        "scripts\start.ps1",
+        "scripts\main.ps1"
+    ) | ForEach-Object {
+        @{
+            Name = $_
+            Path = Join-Path $repoRoot $_
+        }
+    }
+
+    foreach ($scriptCase in $scriptCases) {
+        It "parses $($scriptCase.Name) with the current PowerShell parser" -TestCases $scriptCase {
+            param([string]$Path)
+
+            Test-WinUtilParser -Path $Path
+        }
+    }
+
+    It "parses WinUtil source files with Windows PowerShell when available" {
+        $sourcePaths = @(
+            Join-Path $script:repoRoot "Compile.ps1"
+            Join-Path $script:repoRoot "windev.ps1"
+            Join-Path $script:repoRoot "scripts\start.ps1"
+            Join-Path $script:repoRoot "scripts\main.ps1"
+            Get-ChildItem -Path (Join-Path $script:repoRoot "functions") -Filter *.ps1 -Recurse | Select-Object -ExpandProperty FullName
+        )
+
+        Invoke-WindowsPowerShellParser -Path $sourcePaths
+    }
+}
+
+Describe "Compiled WinUtil sanity" {
+    BeforeAll {
+        $script:compiledPath = Join-Path $script:repoRoot "winutil.ps1"
+
+        Push-Location $script:repoRoot
+        try {
+            & (Join-Path $script:repoRoot "Compile.ps1")
+        } finally {
+            Pop-Location
+        }
+    }
+
+    It "generates winutil.ps1" {
+        Test-Path -Path $script:compiledPath | Should -BeTrue
+    }
+
+    It "parses compiled winutil.ps1 with the current PowerShell parser" {
+        Test-WinUtilParser -Path $script:compiledPath
+    }
+
+    It "parses compiled winutil.ps1 with Windows PowerShell when available" {
+        Invoke-WindowsPowerShellParser -Path $script:compiledPath
+    }
+
+    It "contains embedded configs, XAML, autounattend XML, and runspace bootstrap" {
+        $content = Get-Content -Path $script:compiledPath -Raw
+        $requiredSnippets = @(
+            ('$sync.configs.applications = @' + "'"),
+            ('$inputXML = @' + "'"),
+            ('$WinUtilAutounattendXml = @' + "'"),
+            "SessionStateVariableEntry -ArgumentList 'sync'",
+            "SessionStateFunctionEntry",
+            "[runspacefactory]::CreateRunspacePool",
+            "function Invoke-WPFRunspace"
+        )
+
+        foreach ($snippet in $requiredSnippets) {
+            if (-not $content.Contains($snippet)) {
+                throw "Compiled script is missing expected content: $snippet"
+            }
+        }
+    }
+
+    It "transforms applications config keys with WPFInstall prefixes" {
+        $content = Get-Content -Path $script:compiledPath -Raw
+        $configMatch = [regex]::Match(
+            $content,
+            "(?s)\`$sync\.configs\.applications = @'\r?\n(?<json>.*?)\r?\n'@ \| ConvertFrom-Json"
+        )
+
+        if (-not $configMatch.Success) {
+            throw "Compiled script is missing embedded applications config."
+        }
+
+        $sourceApps = Get-Content -Path (Join-Path $script:repoRoot "config\applications.json") -Raw | ConvertFrom-Json
+        $compiledApps = $configMatch.Groups["json"].Value | ConvertFrom-Json
+
+        foreach ($sourceApp in $sourceApps.PSObject.Properties) {
+            $compiledKey = "WPFInstall$($sourceApp.Name)"
+            if ($compiledApps.PSObject.Properties.Name -notcontains $compiledKey) {
+                throw "Compiled applications config is missing transformed key: $compiledKey"
+            }
+            if ($compiledApps.PSObject.Properties.Name -contains $sourceApp.Name) {
+                throw "Compiled applications config contains untransformed source key: $($sourceApp.Name)"
+            }
+        }
+    }
+
+    It "preserves compile source ordering" {
+        $content = Get-Content -Path $script:compiledPath -Raw
+        $orderedSnippets = @(
+            '$sync.version =',
+            'function Add-SelectedAppsMenuItem',
+            ('$sync.configs.applications = @' + "'"),
+            ('$inputXML = @' + "'"),
+            ('$WinUtilAutounattendXml = @' + "'"),
+            '$sync.SearchBarClearButton.Add_Click({'
+        )
+
+        $lastIndex = -1
+        foreach ($snippet in $orderedSnippets) {
+            $index = $content.IndexOf($snippet)
+            if ($index -lt 0) {
+                throw "Compiled script is missing expected ordered content: $snippet"
+            }
+            if ($index -le $lastIndex) {
+                throw "Compiled script content is out of order near: $snippet"
+            }
+
+            $lastIndex = $index
+        }
+    }
+
+    It "replaces the generated build date placeholder" {
+        $content = Get-Content -Path $script:compiledPath -Raw
+        $expectedBuildDate = Get-Date -Format "yy.MM.dd"
+
+        $content | Should -Not -Match ([regex]::Escape("#{replaceme}"))
+        $content | Should -Match ([regex]::Escape('$sync.version = "' + $expectedBuildDate + '"'))
+    }
+}
+
+Describe "Runspace sanity" {
+    BeforeAll {
+        . (Join-Path $script:repoRoot "functions\public\Invoke-WPFRunspace.ps1")
+    }
+
+    It "returns a single async handle and runs a scriptblock with arguments in the shared runspace pool" {
+        $script:sync = [Hashtable]::Synchronized(@{ SmokeValue = "shared" })
+        $initialSessionState = [System.Management.Automation.Runspaces.InitialSessionState]::CreateDefault()
+        $syncVariable = New-Object System.Management.Automation.Runspaces.SessionStateVariableEntry -ArgumentList "sync", $script:sync, $null
+        $initialSessionState.Variables.Add($syncVariable)
+        $script:sync.runspace = [runspacefactory]::CreateRunspacePool(1, 2, $initialSessionState, $Host)
+        $script:sync.runspace.Open()
+
+        $ended = $false
+        try {
+            $handle = Invoke-WPFRunspace -ArgumentList "argument" -ParameterList @(,("NamedValue", "parameter")) -ScriptBlock {
+                param($ArgumentValue, [string]$NamedValue)
+
+                Start-Sleep -Milliseconds 200
+                "$ArgumentValue|$NamedValue|$($sync.SmokeValue)"
+            }
+
+            ($handle -is [System.IAsyncResult]) | Should -BeTrue
+            ($handle -is [array]) | Should -BeFalse
+            $handle.AsyncWaitHandle.WaitOne(5000) | Should -BeTrue
+
+            $result = $script:powershell.EndInvoke($handle)
+            $ended = $true
+
+            @($result)[0] | Should -Be "argument|parameter|shared"
+        } finally {
+            if (-not $ended -and $handle -and $handle.IsCompleted -and $script:powershell) {
+                try {
+                    $script:powershell.EndInvoke($handle) | Out-Null
+                } catch {
+                    # The assertion failure is more useful than cleanup errors here.
+                }
+            }
+
+            if ($script:powershell) {
+                $script:powershell.Dispose()
+            }
+
+            if ($script:sync -and $script:sync.runspace) {
+                $script:sync.runspace.Close()
+                $script:sync.runspace.Dispose()
+            }
+
+            Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+            Remove-Variable -Name powershell -Scope Script -ErrorAction SilentlyContinue
+            Remove-Variable -Name handle -Scope Script -ErrorAction SilentlyContinue
+        }
+    }
+}
diff --git a/pester/search-filter.Tests.ps1 b/pester/search-filter.Tests.ps1
new file mode 100644
index 00000000..8231f5d1
--- /dev/null
+++ b/pester/search-filter.Tests.ps1
@@ -0,0 +1,446 @@
+#===========================================================================
+# Tests - Search and Filter Helpers
+#===========================================================================
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+
+    if (-not ("Windows.Visibility" -as [type])) {
+        Add-Type @"
+namespace Windows
+{
+    public enum Visibility
+    {
+        Visible,
+        Collapsed
+    }
+}
+"@
+    }
+
+    if (-not ("System.Windows.Controls.CheckBox" -as [type])) {
+        Add-Type @"
+namespace System.Windows.Controls
+{
+    public class CheckBox
+    {
+        public bool? IsChecked { get; set; }
+    }
+
+    public class Label
+    {
+        public object Content { get; set; }
+    }
+
+    public class WrapPanel
+    {
+        public object Visibility { get; set; }
+    }
+
+    public class StackPanel
+    {
+        public System.Collections.ArrayList Children { get; private set; }
+
+        public StackPanel()
+        {
+            Children = new System.Collections.ArrayList();
+        }
+    }
+}
+"@
+    }
+
+    if (-not ("Windows.Controls.Border" -as [type])) {
+        Add-Type @"
+namespace Windows.Controls
+{
+    public class Border
+    {
+        public object Child { get; set; }
+        public object Visibility { get; set; }
+    }
+
+    public class DockPanel
+    {
+        public System.Collections.ArrayList Children { get; private set; }
+        public object Visibility { get; set; }
+
+        public DockPanel()
+        {
+            Children = new System.Collections.ArrayList();
+        }
+    }
+
+    public class StackPanel
+    {
+        public System.Collections.ArrayList Children { get; private set; }
+        public object Visibility { get; set; }
+
+        public StackPanel()
+        {
+            Children = new System.Collections.ArrayList();
+        }
+    }
+
+    public class ItemsControl
+    {
+        public System.Collections.ArrayList Items { get; private set; }
+        public object Visibility { get; set; }
+
+        public ItemsControl()
+        {
+            Items = new System.Collections.ArrayList();
+        }
+    }
+
+    public class Label
+    {
+        public object Content { get; set; }
+        public object ToolTip { get; set; }
+        public object Visibility { get; set; }
+    }
+
+    public class CheckBox
+    {
+        public object Content { get; set; }
+        public object ToolTip { get; set; }
+        public object Visibility { get; set; }
+    }
+}
+"@
+    }
+
+    . (Join-Path $script:repoRoot "functions\private\Find-AppsByNameOrDescription.ps1")
+    . (Join-Path $script:repoRoot "functions\private\Find-TweaksByNameOrDescription.ps1")
+
+    function script:New-WinUtilSearchCollection {
+        return ,[System.Collections.ArrayList]::new()
+    }
+
+    function script:New-WinUtilAppSearchItem {
+        param([string]$Tag)
+
+        [pscustomobject]@{
+            Tag = $Tag
+            Visibility = [Windows.Visibility]::Visible
+        }
+    }
+
+    function script:New-WinUtilAppCategory {
+        param(
+            [string]$Label,
+            [object[]]$Items
+        )
+
+        $labelControl = [pscustomobject]@{
+            Content = $Label
+            Visibility = [Windows.Visibility]::Visible
+        }
+        $wrapPanel = [pscustomobject]@{
+            Children = New-WinUtilSearchCollection
+            Visibility = [Windows.Visibility]::Visible
+        }
+
+        foreach ($item in $Items) {
+            $null = $wrapPanel.Children.Add($item)
+        }
+
+        $children = New-WinUtilSearchCollection
+        $null = $children.Add($labelControl)
+        $null = $children.Add($wrapPanel)
+
+        [pscustomobject]@{
+            Children = $children
+            Visibility = [Windows.Visibility]::Visible
+        }
+    }
+
+    function script:New-WinUtilAppSearchContext {
+        param([object[]]$Categories)
+
+        $items = New-WinUtilSearchCollection
+        foreach ($category in $Categories) {
+            $null = $items.Add($category)
+        }
+
+        $script:sync = [Hashtable]::Synchronized(@{
+            ItemsControl = [pscustomobject]@{
+                Items = $items
+            }
+            configs = @{
+                applicationsHashtable = @{
+                    WPFInstallBrowser = [pscustomobject]@{
+                        Content = "Firefox"
+                        Description = "Fast private browser"
+                    }
+                    WPFInstallMedia = [pscustomobject]@{
+                        Content = "VLC"
+                        Description = "Media player"
+                    }
+                    WPFInstallLiteral = [pscustomobject]@{
+                        Content = "Tool [abc]"
+                        Description = "Literal wildcard sample"
+                    }
+                    WPFInstallEditor = [pscustomobject]@{
+                        Content = "Code Editor"
+                        Description = "Text editing"
+                    }
+                }
+            }
+        })
+        $global:sync = $script:sync
+    }
+
+    function script:New-WinUtilFakeSearchForm {
+        param(
+            $TweaksPanel,
+            $AppxPanel
+        )
+
+        $form = [pscustomobject]@{
+            tweakspanel = $TweaksPanel
+            appxpanel = $AppxPanel
+        }
+        $form | Add-Member -MemberType ScriptMethod -Name FindName -Value {
+            param($name)
+
+            return $this.$name
+        }
+
+        $form
+    }
+
+    function script:New-WinUtilTweakLabelItem {
+        param(
+            [string]$Content,
+            [string]$ToolTip = ""
+        )
+
+        $item = [Windows.Controls.DockPanel]::new()
+        $checkbox = [Windows.Controls.CheckBox]::new()
+        $label = [Windows.Controls.Label]::new()
+        $label.Content = $Content
+        $label.ToolTip = $ToolTip
+        $null = $item.Children.Add($checkbox)
+        $null = $item.Children.Add($label)
+        $item.Visibility = [Windows.Visibility]::Visible
+        $item
+    }
+
+    function script:New-WinUtilTweakCheckboxItem {
+        param(
+            [string]$Content,
+            [string]$ToolTip = ""
+        )
+
+        $item = [Windows.Controls.StackPanel]::new()
+        $checkbox = [Windows.Controls.CheckBox]::new()
+        $checkbox.Content = $Content
+        $checkbox.ToolTip = $ToolTip
+        $null = $item.Children.Add($checkbox)
+        $item.Visibility = [Windows.Visibility]::Visible
+        $item
+    }
+
+    function script:New-WinUtilTweakCategory {
+        param(
+            [string]$Label,
+            [object[]]$Items
+        )
+
+        $categoryLabel = [Windows.Controls.Label]::new()
+        $categoryLabel.Content = $Label
+        $categoryLabel.Visibility = [Windows.Visibility]::Visible
+
+        $itemsControl = [Windows.Controls.ItemsControl]::new()
+        $null = $itemsControl.Items.Add($categoryLabel)
+        foreach ($item in $Items) {
+            $null = $itemsControl.Items.Add($item)
+        }
+
+        $dockPanel = [Windows.Controls.DockPanel]::new()
+        $null = $dockPanel.Children.Add($itemsControl)
+
+        $border = [Windows.Controls.Border]::new()
+        $border.Child = $dockPanel
+        $border.Visibility = [Windows.Visibility]::Visible
+
+        [pscustomobject]@{
+            Border = $border
+            Label = $categoryLabel
+            ItemsControl = $itemsControl
+        }
+    }
+
+    function script:New-WinUtilTweakPanel {
+        param([object[]]$Categories)
+
+        $panel = [pscustomobject]@{
+            Children = New-WinUtilSearchCollection
+        }
+
+        foreach ($category in $Categories) {
+            $null = $panel.Children.Add($category.Border)
+        }
+
+        $panel
+    }
+
+    function script:New-WinUtilTweakSearchContext {
+        param(
+            $TweaksPanel,
+            $AppxPanel = $null,
+            [string]$CurrentTab = "Tweaks"
+        )
+
+        $script:sync = [Hashtable]::Synchronized(@{
+            currentTab = $CurrentTab
+            Form = New-WinUtilFakeSearchForm -TweaksPanel $TweaksPanel -AppxPanel $AppxPanel
+        })
+        $global:sync = $script:sync
+    }
+
+    function script:Remove-WinUtilSearchGlobals {
+        Remove-Variable -Name sync -Scope Global -ErrorAction SilentlyContinue
+    }
+}
+
+Describe "Find-AppsByNameOrDescription" {
+    AfterEach {
+        Remove-WinUtilSearchGlobals
+    }
+
+    It "restores app visibility and respects collapsed category state for empty search" {
+        $browserItem = New-WinUtilAppSearchItem -Tag "WPFInstallBrowser"
+        $mediaItem = New-WinUtilAppSearchItem -Tag "WPFInstallMedia"
+        $browserItem.Visibility = [Windows.Visibility]::Collapsed
+        $mediaItem.Visibility = [Windows.Visibility]::Collapsed
+
+        $collapsedCategory = New-WinUtilAppCategory -Label "+ Browsers" -Items @($browserItem)
+        $expandedCategory = New-WinUtilAppCategory -Label "- Media" -Items @($mediaItem)
+        $collapsedCategory.Children[1].Visibility = [Windows.Visibility]::Collapsed
+        $expandedCategory.Children[1].Visibility = [Windows.Visibility]::Collapsed
+        New-WinUtilAppSearchContext -Categories @($collapsedCategory, $expandedCategory)
+
+        Find-AppsByNameOrDescription -SearchString ""
+
+        $collapsedCategory.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $collapsedCategory.Children[0].Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $collapsedCategory.Children[1].Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+        $browserItem.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $expandedCategory.Children[1].Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $mediaItem.Visibility | Should -Be ([Windows.Visibility]::Visible)
+    }
+
+    It "shows matching apps by description and hides categories without matches" {
+        $browserItem = New-WinUtilAppSearchItem -Tag "WPFInstallBrowser"
+        $mediaItem = New-WinUtilAppSearchItem -Tag "WPFInstallMedia"
+        $editorItem = New-WinUtilAppSearchItem -Tag "WPFInstallEditor"
+        $browserCategory = New-WinUtilAppCategory -Label "+ Browsers" -Items @($browserItem, $mediaItem)
+        $editorCategory = New-WinUtilAppCategory -Label "- Editors" -Items @($editorItem)
+        New-WinUtilAppSearchContext -Categories @($browserCategory, $editorCategory)
+
+        Find-AppsByNameOrDescription -SearchString "private"
+
+        $browserCategory.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $browserCategory.Children[0].Content | Should -Be "- Browsers"
+        $browserCategory.Children[1].Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $browserItem.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $mediaItem.Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+        $editorCategory.Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+        $editorItem.Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+    }
+
+    It "treats wildcard characters as literal app search text" {
+        $literalItem = New-WinUtilAppSearchItem -Tag "WPFInstallLiteral"
+        $mediaItem = New-WinUtilAppSearchItem -Tag "WPFInstallMedia"
+        $category = New-WinUtilAppCategory -Label "- Tools" -Items @($literalItem, $mediaItem)
+        New-WinUtilAppSearchContext -Categories @($category)
+
+        Find-AppsByNameOrDescription -SearchString "[abc]"
+
+        $literalItem.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $mediaItem.Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+        $category.Visibility | Should -Be ([Windows.Visibility]::Visible)
+    }
+}
+
+Describe "Find-TweaksByNameOrDescription" {
+    AfterEach {
+        Remove-WinUtilSearchGlobals
+    }
+
+    It "restores category labels and tweak item visibility for empty search" {
+        $labelItem = New-WinUtilTweakLabelItem -Content "Disable Telemetry" -ToolTip "Stop tracking"
+        $stackItem = New-WinUtilTweakCheckboxItem -Content "Show Extensions" -ToolTip "File extension display"
+        $category = New-WinUtilTweakCategory -Label "+ Privacy" -Items @($labelItem, $stackItem)
+        $labelItem.Visibility = [Windows.Visibility]::Collapsed
+        $stackItem.Visibility = [Windows.Visibility]::Collapsed
+        $category.Label.Visibility = [Windows.Visibility]::Collapsed
+        $category.Border.Visibility = [Windows.Visibility]::Collapsed
+        $panel = New-WinUtilTweakPanel -Categories @($category)
+        New-WinUtilTweakSearchContext -TweaksPanel $panel
+
+        Find-TweaksByNameOrDescription -SearchString ""
+
+        $category.Border.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $category.Label.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $labelItem.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $stackItem.Visibility | Should -Be ([Windows.Visibility]::Visible)
+    }
+
+    It "shows tweak matches by label tooltip and checkbox content" {
+        $telemetryItem = New-WinUtilTweakLabelItem -Content "Disable Telemetry" -ToolTip "Stop tracking"
+        $extensionsItem = New-WinUtilTweakCheckboxItem -Content "Show Extensions" -ToolTip "File extension display"
+        $nonMatchItem = New-WinUtilTweakLabelItem -Content "Enable NumLock" -ToolTip "Keyboard setting"
+        $category = New-WinUtilTweakCategory -Label "+ Privacy" -Items @($telemetryItem, $extensionsItem, $nonMatchItem)
+        $panel = New-WinUtilTweakPanel -Categories @($category)
+        New-WinUtilTweakSearchContext -TweaksPanel $panel
+
+        Find-TweaksByNameOrDescription -SearchString "tracking"
+
+        $category.Border.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $category.Label.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $category.Label.Content | Should -Be "- Privacy"
+        $telemetryItem.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $extensionsItem.Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+        $nonMatchItem.Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+
+        Find-TweaksByNameOrDescription -SearchString "Show Extensions"
+
+        $telemetryItem.Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+        $extensionsItem.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $nonMatchItem.Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+    }
+
+    It "hides tweak category panels when no items match" {
+        $item = New-WinUtilTweakLabelItem -Content "Disable Telemetry" -ToolTip "Stop tracking"
+        $category = New-WinUtilTweakCategory -Label "- Privacy" -Items @($item)
+        $panel = New-WinUtilTweakPanel -Categories @($category)
+        New-WinUtilTweakSearchContext -TweaksPanel $panel
+
+        Find-TweaksByNameOrDescription -SearchString "not-present"
+
+        $category.Border.Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+        $category.Label.Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+        $item.Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+    }
+
+    It "searches the AppX panel when AppX is the current tab" {
+        $tweakItem = New-WinUtilTweakLabelItem -Content "Disable Telemetry" -ToolTip "Stop tracking"
+        $appxItem = New-WinUtilTweakCheckboxItem -Content "Xbox Overlay" -ToolTip "Gaming overlay package"
+        $tweakCategory = New-WinUtilTweakCategory -Label "- Privacy" -Items @($tweakItem)
+        $appxCategory = New-WinUtilTweakCategory -Label "+ AppX" -Items @($appxItem)
+        $tweakPanel = New-WinUtilTweakPanel -Categories @($tweakCategory)
+        $appxPanel = New-WinUtilTweakPanel -Categories @($appxCategory)
+        New-WinUtilTweakSearchContext -TweaksPanel $tweakPanel -AppxPanel $appxPanel -CurrentTab "AppX"
+
+        Find-TweaksByNameOrDescription -SearchString "overlay"
+
+        $appxCategory.Border.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $appxCategory.Label.Content | Should -Be "- AppX"
+        $appxItem.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $tweakCategory.Border.Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $tweakItem.Visibility | Should -Be ([Windows.Visibility]::Visible)
+    }
+}
diff --git a/pester/system-helpers.Tests.ps1 b/pester/system-helpers.Tests.ps1
new file mode 100644
index 00000000..875467cc
--- /dev/null
+++ b/pester/system-helpers.Tests.ps1
@@ -0,0 +1,157 @@
+#===========================================================================
+# Tests - System Helper Functions
+#===========================================================================
+
+$repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+    . (Join-Path $script:repoRoot "functions\private\Set-WinUtilRegistry.ps1")
+    . (Join-Path $script:repoRoot "functions\private\Set-WinUtilService.ps1")
+
+    function Write-WinUtilLog { }
+}
+
+Describe "Set-WinUtilRegistry" {
+    BeforeEach {
+        $script:testPathResults = @{}
+
+        Mock Write-Host { }
+        Mock Write-Warning { }
+        Mock Write-WinUtilLog { }
+        Mock Test-Path {
+            param([string]$Path)
+
+            if ($script:testPathResults.ContainsKey($Path)) {
+                return $script:testPathResults[$Path]
+            }
+
+            throw "Unexpected Test-Path call: $Path"
+        }
+        Mock New-PSDrive { }
+        Mock New-Item { }
+        Mock Set-ItemProperty { }
+        Mock Remove-ItemProperty { }
+    }
+
+    It "creates a missing registry path before setting a value" {
+        $registryPath = "HKCU:\Software\WinUtilTest"
+        $script:testPathResults["HKU:\"] = $true
+        $script:testPathResults[$registryPath] = $false
+
+        Set-WinUtilRegistry -Path $registryPath -Name "Enabled" -Type "DWord" -Value "1"
+
+        Should -Invoke -CommandName New-PSDrive -Times 0 -Exactly
+        Should -Invoke -CommandName New-Item -Times 1 -Exactly -ParameterFilter {
+            $Path -eq $registryPath -and $Force -eq $true -and $ErrorAction -eq "Stop"
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq $registryPath -and
+                $Name -eq "Enabled" -and
+                $Type -eq "DWord" -and
+                $Value -eq "1" -and
+                $Force -eq $true -and
+                $ErrorAction -eq "Stop"
+        }
+        Should -Invoke -CommandName Remove-ItemProperty -Times 0 -Exactly
+    }
+
+    It "creates the HKU PSDrive when it is missing" {
+        $registryPath = "HKCU:\Software\WinUtilTest"
+        $script:testPathResults["HKU:\"] = $false
+        $script:testPathResults[$registryPath] = $true
+
+        Set-WinUtilRegistry -Path $registryPath -Name "Enabled" -Type "DWord" -Value "1"
+
+        Should -Invoke -CommandName New-PSDrive -Times 1 -Exactly -ParameterFilter {
+            $PSProvider -eq "Registry" -and
+                $Name -eq "HKU" -and
+                $Root -eq "HKEY_USERS"
+        }
+        Should -Invoke -CommandName New-Item -Times 0 -Exactly
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq $registryPath -and $Name -eq "Enabled" -and $Type -eq "DWord" -and $Value -eq "1"
+        }
+    }
+
+    It "removes a registry value when requested" {
+        $registryPath = "HKLM:\Software\WinUtilTest"
+        $script:testPathResults["HKU:\"] = $true
+        $script:testPathResults[$registryPath] = $true
+
+        Set-WinUtilRegistry -Path $registryPath -Name "ObsoleteValue" -Type "String" -Value "<RemoveEntry>"
+
+        Should -Invoke -CommandName Set-ItemProperty -Times 0 -Exactly
+        Should -Invoke -CommandName Remove-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq $registryPath -and
+                $Name -eq "ObsoleteValue" -and
+                $Force -eq $true -and
+                $ErrorAction -eq "Stop"
+        }
+    }
+}
+
+Describe "Set-WinUtilService" {
+    BeforeEach {
+        Mock Write-Host { }
+        Mock Write-Warning { }
+        Mock Write-WinUtilLog { }
+        Mock Get-Service { }
+        Mock Set-Service { }
+    }
+
+    It "sets the startup type for an existing service" {
+        Mock Get-Service {
+            [pscustomobject]@{
+                Name = "DiagTrack"
+                StartType = "Automatic"
+            }
+        } -ParameterFilter { $Name -eq "DiagTrack" -and $ErrorAction -eq "Stop" }
+
+        Set-WinUtilService -Name "DiagTrack" -StartupType "Disabled"
+
+        Should -Invoke -CommandName Get-Service -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "DiagTrack" -and $ErrorAction -eq "Stop"
+        }
+        Should -Invoke -CommandName Set-Service -Times 1 -Exactly -ParameterFilter {
+            $StartupType -eq "Disabled" -and $ErrorAction -eq "Stop"
+        }
+    }
+
+    It "does not change a service that already has the requested startup type" {
+        Mock Get-Service {
+            [pscustomobject]@{
+                Name = "DiagTrack"
+                StartType = "Disabled"
+            }
+        } -ParameterFilter { $Name -eq "DiagTrack" -and $ErrorAction -eq "Stop" }
+
+        Set-WinUtilService -Name "DiagTrack" -StartupType "Disabled"
+
+        Should -Invoke -CommandName Get-Service -Times 1 -Exactly
+        Should -Invoke -CommandName Set-Service -Times 0 -Exactly
+    }
+
+    It "does not call Set-Service when the service is missing" {
+        Mock Get-Service {
+            $exception = [Microsoft.PowerShell.Commands.ServiceCommandException]::new("Cannot find any service with service name '$Name'.")
+            $errorRecord = [System.Management.Automation.ErrorRecord]::new(
+                $exception,
+                "NoServiceFoundForGivenName,Microsoft.PowerShell.Commands.GetServiceCommand",
+                [System.Management.Automation.ErrorCategory]::ObjectNotFound,
+                $Name
+            )
+            throw $errorRecord
+        } -ParameterFilter { $Name -eq "MissingService" -and $ErrorAction -eq "Stop" }
+
+        Set-WinUtilService -Name "MissingService" -StartupType "Disabled"
+
+        Should -Invoke -CommandName Get-Service -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "MissingService" -and $ErrorAction -eq "Stop"
+        }
+        Should -Invoke -CommandName Set-Service -Times 0 -Exactly
+        Should -Invoke -CommandName Write-Warning -Times 1 -Exactly -ParameterFilter {
+            $Message -eq "Service MissingService was not found."
+        }
+    }
+}
diff --git a/pester/tweaks.Tests.ps1 b/pester/tweaks.Tests.ps1
new file mode 100644
index 00000000..7eda9d2d
--- /dev/null
+++ b/pester/tweaks.Tests.ps1
@@ -0,0 +1,231 @@
+#===========================================================================
+# Tests - Tweak Orchestration
+#===========================================================================
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+    . (Join-Path $script:repoRoot "functions\private\Invoke-WinUtilTweaks.ps1")
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFtweaksbutton.ps1")
+
+    function Set-WinUtilService {
+        param($Name, $StartupType)
+    }
+    function Set-WinUtilRegistry {
+        param($Name, $Path, $Type, $Value)
+    }
+    function Invoke-WinUtilScript {
+        param($Name, [scriptblock]$ScriptBlock)
+    }
+    function Remove-WinUtilAPPX {
+        param($Name)
+    }
+    function Set-WinUtilDNS {
+        param($DNSProvider)
+    }
+    function Invoke-WPFRunspace {
+        param($ArgumentList, $ParameterList, [scriptblock]$ScriptBlock)
+    }
+    function Invoke-WPFUIThread {
+        param([scriptblock]$ScriptBlock)
+    }
+    function Set-WinUtilProgressBar {
+        param($Label, $Percent)
+    }
+    function Write-WinUtilLog {
+        param($Message, $Level, $Component)
+    }
+
+    function script:New-WinUtilTweaksConfig {
+        [pscustomobject]@{
+            WPFTweaksExample = [pscustomobject]@{
+                service = @(
+                    [pscustomobject]@{
+                        Name = "DiagTrack"
+                        StartupType = "Disabled"
+                        OriginalType = "Automatic"
+                    }
+                )
+                registry = @(
+                    [pscustomobject]@{
+                        Path = "HKLM:\Software\WinUtilTest"
+                        Name = "AllowTelemetry"
+                        Type = "DWord"
+                        Value = "0"
+                        OriginalValue = "1"
+                    }
+                )
+                InvokeScript = @("Write-Output 'apply tweak'")
+                UndoScript = @("Write-Output 'undo tweak'")
+                appx = @("Microsoft.ExampleApp")
+            }
+            WPFTweaksServiceOnly = [pscustomobject]@{
+                service = @(
+                    [pscustomobject]@{
+                        Name = "DiagTrack"
+                        StartupType = "Disabled"
+                        OriginalType = "Automatic"
+                    }
+                )
+            }
+        }
+    }
+}
+
+Describe "Invoke-WinUtilTweaks" {
+    BeforeEach {
+        $script:sync = [Hashtable]::Synchronized(@{
+            configs = @{
+                tweaks = New-WinUtilTweaksConfig
+            }
+        })
+
+        Mock Get-Service {
+            [pscustomobject]@{
+                Name = "DiagTrack"
+                StartType = "Automatic"
+            }
+        }
+        Mock Set-WinUtilService { }
+        Mock Set-WinUtilRegistry { }
+        Mock Invoke-WinUtilScript { }
+        Mock Remove-WinUtilAPPX { }
+        Mock Write-WinUtilLog { }
+        Mock Write-Warning { }
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+    }
+
+    It "dispatches apply actions to service, registry, script, and AppX helpers" {
+        Invoke-WinUtilTweaks -CheckBox "WPFTweaksExample"
+
+        Should -Invoke -CommandName Get-Service -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "DiagTrack" -and $ErrorAction -eq "Stop"
+        }
+        Should -Invoke -CommandName Set-WinUtilService -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "DiagTrack" -and $StartupType -eq "Disabled"
+        }
+        Should -Invoke -CommandName Set-WinUtilRegistry -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\Software\WinUtilTest" -and
+                $Name -eq "AllowTelemetry" -and
+                $Type -eq "DWord" -and
+                $Value -eq "0"
+        }
+        Should -Invoke -CommandName Invoke-WinUtilScript -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "WPFTweaksExample" -and $ScriptBlock.ToString() -eq "Write-Output 'apply tweak'"
+        }
+        Should -Invoke -CommandName Remove-WinUtilAPPX -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "Microsoft.ExampleApp"
+        }
+    }
+
+    It "uses original registry values and service startup types in undo mode" {
+        Invoke-WinUtilTweaks -CheckBox "WPFTweaksExample" -undo $true
+
+        Should -Invoke -CommandName Get-Service -Times 0 -Exactly
+        Should -Invoke -CommandName Set-WinUtilService -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "DiagTrack" -and $StartupType -eq "Automatic"
+        }
+        Should -Invoke -CommandName Set-WinUtilRegistry -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\Software\WinUtilTest" -and
+                $Name -eq "AllowTelemetry" -and
+                $Type -eq "DWord" -and
+                $Value -eq "1"
+        }
+        Should -Invoke -CommandName Invoke-WinUtilScript -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "WPFTweaksExample" -and $ScriptBlock.ToString() -eq "Write-Output 'undo tweak'"
+        }
+        Should -Invoke -CommandName Remove-WinUtilAPPX -Times 0 -Exactly
+    }
+
+    It "keeps a user-changed service startup type by default" {
+        Mock Get-Service {
+            [pscustomobject]@{
+                Name = "DiagTrack"
+                StartType = "Manual"
+            }
+        } -ParameterFilter { $Name -eq "DiagTrack" }
+
+        Invoke-WinUtilTweaks -CheckBox "WPFTweaksServiceOnly"
+
+        Should -Invoke -CommandName Get-Service -Times 1 -Exactly
+        Should -Invoke -CommandName Set-WinUtilService -Times 0 -Exactly
+    }
+
+    It "forces a service startup type when KeepServiceStartup is disabled" {
+        Invoke-WinUtilTweaks -CheckBox "WPFTweaksServiceOnly" -KeepServiceStartup $false
+
+        Should -Invoke -CommandName Get-Service -Times 0 -Exactly
+        Should -Invoke -CommandName Set-WinUtilService -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "DiagTrack" -and $StartupType -eq "Disabled"
+        }
+    }
+}
+
+Describe "Invoke-WPFtweaksbutton" {
+    BeforeEach {
+        $script:sync = [Hashtable]::Synchronized(@{
+            ProcessRunning = $false
+            selectedTweaks = [System.Collections.Generic.List[string]]::new()
+            WPFchangedns = [pscustomobject]@{
+                text = "Cloudflare"
+            }
+        })
+
+        Mock Invoke-WPFRunspace { [pscustomobject]@{ MockHandle = $true } }
+        Mock Invoke-WinUtilTweaks { }
+        Mock Invoke-WPFUIThread { }
+        Mock Set-WinUtilProgressBar { }
+        Mock Write-WinUtilLog { }
+        Mock Write-Host { }
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+    }
+
+    It "passes selected tweaks, DNS provider, and progress counters to the tweak runspace" {
+        $script:sync.selectedTweaks.Add("WPFTweaksTelemetry")
+        $script:sync.selectedTweaks.Add("WPFTweaksServices")
+
+        Invoke-WPFtweaksbutton
+
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 1 -Exactly -ParameterFilter {
+            $ParameterList.Count -eq 4 -and
+                $ParameterList[0][0] -eq "tweaks" -and
+                $ParameterList[0][1].Count -eq 2 -and
+                $ParameterList[0][1][0] -eq "WPFTweaksTelemetry" -and
+                $ParameterList[0][1][1] -eq "WPFTweaksServices" -and
+                $ParameterList[1][0] -eq "dnsProvider" -and
+                $ParameterList[1][1] -eq "Cloudflare" -and
+                $ParameterList[2][0] -eq "completedSteps" -and
+                $ParameterList[2][1] -eq 0 -and
+                $ParameterList[3][0] -eq "totalSteps" -and
+                $ParameterList[3][1] -eq 2
+        }
+    }
+
+    It "runs the restore point first and advances progress before queueing remaining tweaks" {
+        $script:sync.selectedTweaks.Add("WPFTweaksRestorePoint")
+        $script:sync.selectedTweaks.Add("WPFTweaksTelemetry")
+
+        Invoke-WPFtweaksbutton
+
+        Should -Invoke -CommandName Invoke-WinUtilTweaks -Times 1 -Exactly -ParameterFilter {
+            $CheckBox -eq "WPFTweaksRestorePoint"
+        }
+        Should -Invoke -CommandName Invoke-WPFRunspace -Times 1 -Exactly -ParameterFilter {
+            $ParameterList.Count -eq 4 -and
+                $ParameterList[0][0] -eq "tweaks" -and
+                $ParameterList[0][1].Count -eq 1 -and
+                $ParameterList[0][1][0] -eq "WPFTweaksTelemetry" -and
+                $ParameterList[1][0] -eq "dnsProvider" -and
+                $ParameterList[1][1] -eq "Cloudflare" -and
+                $ParameterList[2][0] -eq "completedSteps" -and
+                $ParameterList[2][1] -eq 1 -and
+                $ParameterList[3][0] -eq "totalSteps" -and
+                $ParameterList[3][1] -eq 2
+        }
+    }
+}
diff --git a/pester/ui-state.Tests.ps1 b/pester/ui-state.Tests.ps1
new file mode 100644
index 00000000..0b2a9488
--- /dev/null
+++ b/pester/ui-state.Tests.ps1
@@ -0,0 +1,274 @@
+#===========================================================================
+# Tests - UI Selection and State Helpers
+#===========================================================================
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+
+    if (-not ("System.Windows.Controls.CheckBox" -as [type])) {
+        Add-Type @"
+namespace Windows
+{
+    public enum Visibility
+    {
+        Visible,
+        Collapsed
+    }
+}
+
+namespace System.Windows.Controls
+{
+    public class CheckBox
+    {
+        public bool? IsChecked { get; set; }
+    }
+
+    public class Label
+    {
+        public object Content { get; set; }
+    }
+
+    public class WrapPanel
+    {
+        public global::Windows.Visibility Visibility { get; set; }
+    }
+
+    public class StackPanel
+    {
+        public System.Collections.ArrayList Children { get; } = new System.Collections.ArrayList();
+    }
+}
+"@
+    }
+
+    . (Join-Path $script:repoRoot "functions\private\Update-WinUtilSelections.ps1")
+    . (Join-Path $script:repoRoot "functions\private\Reset-WPFCheckBoxes.ps1")
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFSelectedCheckboxesUpdate.ps1")
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFToggleAllCategories.ps1")
+
+    function script:New-WinUtilFakeCheckBox {
+        param([bool]$IsChecked = $false)
+
+        $checkbox = [System.Windows.Controls.CheckBox]::new()
+        $checkbox.IsChecked = $IsChecked
+        $checkbox
+    }
+
+    function script:New-WinUtilFakeCategory {
+        param(
+            [string]$Label,
+            [Windows.Visibility]$Visibility
+        )
+
+        $category = [System.Windows.Controls.StackPanel]::new()
+        $categoryLabel = [System.Windows.Controls.Label]::new()
+        $categoryLabel.Content = $Label
+        $wrapPanel = [System.Windows.Controls.WrapPanel]::new()
+        $wrapPanel.Visibility = $Visibility
+
+        $null = $category.Children.Add($categoryLabel)
+        $null = $category.Children.Add($wrapPanel)
+
+        $category
+    }
+
+    function script:New-WinUtilUiStateTestContext {
+        $testSync = [Hashtable]::Synchronized(@{
+            selectedApps = [System.Collections.Generic.List[string]]::new()
+            selectedTweaks = [System.Collections.Generic.List[string]]::new()
+            selectedToggles = [System.Collections.Generic.List[string]]::new()
+            selectedFeatures = [System.Collections.Generic.List[string]]::new()
+            selectedAppx = [System.Collections.Generic.List[string]]::new()
+            configs = @{
+                applicationsHashtable = @{
+                    WPFInstallGit = [pscustomobject]@{
+                        Content = "Git"
+                    }
+                }
+            }
+            WPFselectedAppsButton = [pscustomobject]@{
+                Content = ""
+            }
+            selectedAppsstackPanel = [pscustomobject]@{
+                Children = [System.Collections.ArrayList]::new()
+            }
+        })
+        $script:sync = $testSync
+        $global:sync = $testSync
+    }
+
+    function Add-SelectedAppsMenuItem {
+        param($name, $key)
+
+        $null = $global:sync.selectedAppsstackPanel.Children.Add([pscustomobject]@{
+            Name = $name
+            Key = $key
+        })
+    }
+}
+
+Describe "Update-WinUtilSelections" {
+    BeforeEach {
+        New-WinUtilUiStateTestContext
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name sync -Scope Global -ErrorAction SilentlyContinue
+    }
+
+    It "adds imported checkbox keys to the matching selected lists" {
+        Update-WinUtilSelections @(
+            "WPFInstallGit",
+            "WPFTweaksTelemetry",
+            "WPFToggleDarkMode",
+            "WPFFeatureSandbox",
+            "WPFAppxExample"
+        )
+
+        @($script:sync.selectedApps) | Should -Be @("WPFInstallGit")
+        @($script:sync.selectedTweaks) | Should -Be @("WPFTweaksTelemetry")
+        @($script:sync.selectedToggles) | Should -Be @("WPFToggleDarkMode")
+        @($script:sync.selectedFeatures) | Should -Be @("WPFFeatureSandbox")
+        @($script:sync.selectedAppx) | Should -Be @("WPFAppxExample")
+    }
+}
+
+Describe "Invoke-WPFSelectedCheckboxesUpdate" {
+    BeforeEach {
+        New-WinUtilUiStateTestContext
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name sync -Scope Global -ErrorAction SilentlyContinue
+    }
+
+    It "adds each checkbox family without duplicating existing selections" {
+        Invoke-WPFSelectedCheckboxesUpdate -type "Add" -checkboxName "WPFInstallGit"
+        Invoke-WPFSelectedCheckboxesUpdate -type "Add" -checkboxName "WPFInstallGit"
+        Invoke-WPFSelectedCheckboxesUpdate -type "Add" -checkboxName "WPFTweaksTelemetry"
+        Invoke-WPFSelectedCheckboxesUpdate -type "Add" -checkboxName "WPFToggleDarkMode"
+        Invoke-WPFSelectedCheckboxesUpdate -type "Add" -checkboxName "WPFFeatureSandbox"
+        Invoke-WPFSelectedCheckboxesUpdate -type "Add" -checkboxName "WPFAppxExample"
+
+        @($script:sync.selectedApps) | Should -Be @("WPFInstallGit")
+        @($script:sync.selectedTweaks) | Should -Be @("WPFTweaksTelemetry")
+        @($script:sync.selectedToggles) | Should -Be @("WPFToggleDarkMode")
+        @($script:sync.selectedFeatures) | Should -Be @("WPFFeatureSandbox")
+        @($script:sync.selectedAppx) | Should -Be @("WPFAppxExample")
+    }
+
+    It "removes checkbox keys from the matching selected lists" {
+        $script:sync.selectedApps.Add("WPFInstallGit")
+        $script:sync.selectedTweaks.Add("WPFTweaksTelemetry")
+        $script:sync.selectedToggles.Add("WPFToggleDarkMode")
+        $script:sync.selectedFeatures.Add("WPFFeatureSandbox")
+        $script:sync.selectedAppx.Add("WPFAppxExample")
+
+        Invoke-WPFSelectedCheckboxesUpdate -type "Remove" -checkboxName "WPFInstallGit"
+        Invoke-WPFSelectedCheckboxesUpdate -type "Remove" -checkboxName "WPFTweaksTelemetry"
+        Invoke-WPFSelectedCheckboxesUpdate -type "Remove" -checkboxName "WPFToggleDarkMode"
+        Invoke-WPFSelectedCheckboxesUpdate -type "Remove" -checkboxName "WPFFeatureSandbox"
+        Invoke-WPFSelectedCheckboxesUpdate -type "Remove" -checkboxName "WPFAppxExample"
+
+        $script:sync.selectedApps.Count | Should -Be 0
+        $script:sync.selectedTweaks.Count | Should -Be 0
+        $script:sync.selectedToggles.Count | Should -Be 0
+        $script:sync.selectedFeatures.Count | Should -Be 0
+        $script:sync.selectedAppx.Count | Should -Be 0
+    }
+}
+
+Describe "Reset-WPFCheckBoxes" {
+    BeforeEach {
+        New-WinUtilUiStateTestContext
+
+        $script:sync.selectedApps.Add("WPFInstallGit")
+        $script:sync.selectedTweaks.Add("WPFTweaksTelemetry")
+        $script:sync.selectedFeatures.Add("WPFFeatureSandbox")
+        $script:sync.selectedAppx.Add("WPFAppxExample")
+        $script:sync.selectedToggles.Add("WPFToggleDarkMode")
+
+        $script:sync.WPFInstallGit = New-WinUtilFakeCheckBox
+        $script:sync.WPFInstallVlc = New-WinUtilFakeCheckBox -IsChecked $true
+        $script:sync.WPFTweaksTelemetry = New-WinUtilFakeCheckBox
+        $script:sync.WPFFeatureSandbox = New-WinUtilFakeCheckBox
+        $script:sync.WPFAppxExample = New-WinUtilFakeCheckBox
+        $script:sync.WPFToggleDarkMode = New-WinUtilFakeCheckBox
+        $script:sync.WPFToggleOther = New-WinUtilFakeCheckBox -IsChecked $true
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name sync -Scope Global -ErrorAction SilentlyContinue
+    }
+
+    It "syncs non-toggle checkboxes from selected lists and updates selected app UI state" {
+        Reset-WPFCheckBoxes
+
+        $script:sync.WPFInstallGit.IsChecked | Should -BeTrue
+        $script:sync.WPFInstallVlc.IsChecked | Should -BeFalse
+        $script:sync.WPFTweaksTelemetry.IsChecked | Should -BeTrue
+        $script:sync.WPFFeatureSandbox.IsChecked | Should -BeTrue
+        $script:sync.WPFAppxExample.IsChecked | Should -BeTrue
+        $script:sync.WPFToggleDarkMode.IsChecked | Should -BeFalse
+        $script:sync.WPFselectedAppsButton.Content | Should -Be "Selected Apps: 1"
+        $script:sync.selectedAppsstackPanel.Children.Count | Should -Be 1
+        $script:sync.selectedAppsstackPanel.Children[0].Name | Should -Be "Git"
+        $script:sync.selectedAppsstackPanel.Children[0].Key | Should -Be "WPFInstallGit"
+    }
+
+    It "restores imported toggles when requested without changing absent toggles" {
+        Reset-WPFCheckBoxes -doToggles $true
+
+        $script:sync.WPFToggleDarkMode.IsChecked | Should -BeTrue
+        $script:sync.WPFToggleOther.IsChecked | Should -BeTrue
+    }
+}
+
+Describe "Invoke-WPFToggleAllCategories" {
+    BeforeEach {
+        New-WinUtilUiStateTestContext
+
+        $script:sync.ItemsControl = [pscustomobject]@{
+            Items = [System.Collections.ArrayList]::new()
+        }
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name sync -Scope Global -ErrorAction SilentlyContinue
+    }
+
+    It "expands all install categories and updates collapsed labels" {
+        $category = New-WinUtilFakeCategory -Label "+ Browsers" -Visibility ([Windows.Visibility]::Collapsed)
+        $null = $script:sync.ItemsControl.Items.Add($category)
+
+        Invoke-WPFToggleAllCategories -Action "Expand"
+
+        $category.Children[1].Visibility | Should -Be ([Windows.Visibility]::Visible)
+        $category.Children[0].Content | Should -Be "- Browsers"
+    }
+
+    It "collapses all install categories and updates expanded labels" {
+        $category = New-WinUtilFakeCategory -Label "- Browsers" -Visibility ([Windows.Visibility]::Visible)
+        $null = $script:sync.ItemsControl.Items.Add($category)
+
+        Invoke-WPFToggleAllCategories -Action "Collapse"
+
+        $category.Children[1].Visibility | Should -Be ([Windows.Visibility]::Collapsed)
+        $category.Children[0].Content | Should -Be "+ Browsers"
+    }
+
+    It "warns and exits when ItemsControl is not initialized" {
+        $script:sync.ItemsControl = $null
+        Mock Write-Warning { }
+
+        Invoke-WPFToggleAllCategories -Action "Expand"
+
+        Should -Invoke -CommandName Write-Warning -Times 1 -Exactly -ParameterFilter {
+            $Message -eq "ItemsControl not initialized"
+        }
+    }
+}
diff --git a/pester/update-profiles.Tests.ps1 b/pester/update-profiles.Tests.ps1
new file mode 100644
index 00000000..161b49f0
--- /dev/null
+++ b/pester/update-profiles.Tests.ps1
@@ -0,0 +1,294 @@
+#===========================================================================
+# Tests - Windows Update Profiles
+#===========================================================================
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFUpdatesdisable.ps1")
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFUpdatesdefault.ps1")
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFUpdatessecurity.ps1")
+
+    function Write-WinUtilLog {
+        param($Message, $Level, $Component)
+    }
+    function Get-ScheduledTask {
+        param($TaskPath)
+    }
+    function Disable-ScheduledTask {
+        param(
+            [Parameter(ValueFromPipeline = $true)]
+            $InputObject,
+            $ErrorAction
+        )
+        process { }
+    }
+    function Enable-ScheduledTask {
+        param(
+            [Parameter(ValueFromPipeline = $true)]
+            $InputObject,
+            $ErrorAction
+        )
+        process { }
+    }
+    function secedit {
+        param(
+            [Parameter(ValueFromRemainingArguments = $true)]
+            $Arguments
+        )
+    }
+
+    $script:updateTaskPaths = @(
+        '\Microsoft\Windows\InstallService\*',
+        '\Microsoft\Windows\UpdateOrchestrator\*',
+        '\Microsoft\Windows\UpdateAssistant\*',
+        '\Microsoft\Windows\WaaSMedic\*',
+        '\Microsoft\Windows\WindowsUpdate\*',
+        '\Microsoft\WindowsUpdate\*'
+    )
+}
+
+Describe "Invoke-WPFUpdatesdisable" {
+    BeforeEach {
+        Mock Write-Host { }
+        Mock Write-WinUtilLog { }
+        Mock New-Item { }
+        Mock Set-ItemProperty { }
+        Mock Set-Service { }
+        Mock Stop-Service { }
+        Mock Remove-Item { }
+        Mock Get-ScheduledTask {
+            [pscustomobject]@{
+                TaskPath = $TaskPath
+            }
+        }
+        Mock Disable-ScheduledTask { }
+    }
+
+    It "sets update disable registry policy values" {
+        Invoke-WPFUpdatesdisable
+
+        Should -Invoke -CommandName New-Item -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -and $Force -eq $true
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -and
+                $Name -eq "NoAutoUpdate" -and
+                $Type -eq "DWord" -and
+                $Value -eq 1
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -and
+                $Name -eq "AUOptions" -and
+                $Type -eq "DWord" -and
+                $Value -eq 1
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\DeliveryOptimization\Config" -and
+                $Name -eq "DODownloadMode" -and
+                $Type -eq "DWord" -and
+                $Value -eq 0
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer" -and
+                $Name -eq "SettingsPageVisibility" -and
+                $Value -eq "hide:windowsupdate"
+        }
+    }
+
+    It "disables update services and clears the SoftwareDistribution folder" {
+        Invoke-WPFUpdatesdisable
+
+        Should -Invoke -CommandName Set-Service -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "BITS" -and $StartupType -eq "Disabled"
+        }
+        Should -Invoke -CommandName Set-Service -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "wuauserv" -and $StartupType -eq "Disabled"
+        }
+        Should -Invoke -CommandName Stop-Service -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "UsoSvc" -and $Force -eq $true
+        }
+        Should -Invoke -CommandName Set-Service -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "UsoSvc" -and $StartupType -eq "Disabled"
+        }
+        Should -Invoke -CommandName Remove-Item -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "C:\Windows\SoftwareDistribution\*" -and
+                $Recurse -eq $true -and
+                $Force -eq $true
+        }
+    }
+
+    It "disables update scheduled task paths" {
+        Invoke-WPFUpdatesdisable
+
+        foreach ($expectedTaskPath in $script:updateTaskPaths) {
+            $expected = $expectedTaskPath
+            Should -Invoke -CommandName Get-ScheduledTask -Times 1 -Exactly -ParameterFilter {
+                $TaskPath -eq $expected
+            }
+        }
+        Should -Invoke -CommandName Disable-ScheduledTask -Times $script:updateTaskPaths.Count -Exactly
+    }
+}
+
+Describe "Invoke-WPFUpdatesdefault" {
+    BeforeEach {
+        Mock Write-Host { }
+        Mock Write-WinUtilLog { }
+        Mock Remove-Item { }
+        Mock Remove-ItemProperty { }
+        Mock Set-Service { }
+        Mock Start-Service { }
+        Mock Get-ScheduledTask {
+            [pscustomobject]@{
+                TaskPath = $TaskPath
+            }
+        }
+        Mock Enable-ScheduledTask { }
+        Mock secedit { }
+    }
+
+    It "removes update policy registry paths and shows the Windows Update settings page" {
+        Invoke-WPFUpdatesdefault
+
+        $expectedPaths = @(
+            "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU",
+            "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\DeliveryOptimization",
+            "HKLM:\SOFTWARE\Microsoft\WindowsUpdate\UX\Settings",
+            "HKLM:\SOFTWARE\Policies\Microsoft\Windows\Device Metadata",
+            "HKLM:\SOFTWARE\Policies\Microsoft\Windows\DriverSearching",
+            "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate"
+        )
+
+        foreach ($expectedRegistryPath in $expectedPaths) {
+            $expected = $expectedRegistryPath
+            Should -Invoke -CommandName Remove-Item -Times 1 -Exactly -ParameterFilter {
+                $Path -eq $expected -and $Recurse -eq $true -and $Force -eq $true
+            }
+        }
+        Should -Invoke -CommandName Remove-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer" -and
+                $Name -eq "SettingsPageVisibility"
+        }
+    }
+
+    It "restores update service startup types" {
+        Invoke-WPFUpdatesdefault
+
+        Should -Invoke -CommandName Set-Service -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "BITS" -and $StartupType -eq "Manual"
+        }
+        Should -Invoke -CommandName Set-Service -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "wuauserv" -and $StartupType -eq "Manual"
+        }
+        Should -Invoke -CommandName Start-Service -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "UsoSvc"
+        }
+        Should -Invoke -CommandName Set-Service -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "UsoSvc" -and $StartupType -eq "Automatic"
+        }
+        Should -Invoke -CommandName Set-Service -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "WaaSMedicSvc" -and $StartupType -eq "Manual"
+        }
+    }
+
+    It "enables update scheduled task paths and resets local policy defaults" {
+        Invoke-WPFUpdatesdefault
+
+        foreach ($expectedTaskPath in $script:updateTaskPaths) {
+            $expected = $expectedTaskPath
+            Should -Invoke -CommandName Get-ScheduledTask -Times 1 -Exactly -ParameterFilter {
+                $TaskPath -eq $expected
+            }
+        }
+        Should -Invoke -CommandName Enable-ScheduledTask -Times $script:updateTaskPaths.Count -Exactly
+        Should -Invoke -CommandName secedit -Times 1 -Exactly -ParameterFilter {
+            $Arguments[0] -eq "/configure" -and
+                $Arguments[1] -eq "/cfg" -and
+                $Arguments[2] -like "*\inf\defltbase.inf" -and
+                $Arguments[3] -eq "/db" -and
+                $Arguments[4] -eq "defltbase.sdb"
+        }
+    }
+}
+
+Describe "Invoke-WPFUpdatessecurity" {
+    BeforeEach {
+        Mock Write-Host { }
+        Mock Write-WinUtilLog { }
+        Mock New-Item { }
+        Mock Set-ItemProperty { }
+    }
+
+    It "disables driver metadata and Windows Update driver search" {
+        Invoke-WPFUpdatessecurity
+
+        Should -Invoke -CommandName New-Item -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Policies\Microsoft\Windows\Device Metadata" -and $Force -eq $true
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Policies\Microsoft\Windows\Device Metadata" -and
+                $Name -eq "PreventDeviceMetadataFromNetwork" -and
+                $Type -eq "DWord" -and
+                $Value -eq 1
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Policies\Microsoft\Windows\DriverSearching" -and
+                $Name -eq "DontPromptForWindowsUpdate" -and
+                $Type -eq "DWord" -and
+                $Value -eq 1
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Policies\Microsoft\Windows\DriverSearching" -and
+                $Name -eq "DontSearchWindowsUpdate" -and
+                $Type -eq "DWord" -and
+                $Value -eq 1
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Policies\Microsoft\Windows\DriverSearching" -and
+                $Name -eq "DriverUpdateWizardWuSearchEnabled" -and
+                $Type -eq "DWord" -and
+                $Value -eq 0
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" -and
+                $Name -eq "ExcludeWUDriversInQualityUpdate" -and
+                $Type -eq "DWord" -and
+                $Value -eq 1
+        }
+    }
+
+    It "sets recommended update deferral and auto-reboot policy values" {
+        Invoke-WPFUpdatessecurity
+
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Microsoft\WindowsUpdate\UX\Settings" -and
+                $Name -eq "BranchReadinessLevel" -and
+                $Type -eq "DWord" -and
+                $Value -eq 20
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Microsoft\WindowsUpdate\UX\Settings" -and
+                $Name -eq "DeferFeatureUpdatesPeriodInDays" -and
+                $Type -eq "DWord" -and
+                $Value -eq 365
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Microsoft\WindowsUpdate\UX\Settings" -and
+                $Name -eq "DeferQualityUpdatesPeriodInDays" -and
+                $Type -eq "DWord" -and
+                $Value -eq 4
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -and
+                $Name -eq "NoAutoRebootWithLoggedOnUsers" -and
+                $Type -eq "DWord" -and
+                $Value -eq 1
+        }
+        Should -Invoke -CommandName Set-ItemProperty -Times 1 -Exactly -ParameterFilter {
+            $Path -eq "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -and
+                $Name -eq "AUPowerManagement" -and
+                $Type -eq "DWord" -and
+                $Value -eq 0
+        }
+    }
+}
diff --git a/pester/win11creator.Tests.ps1 b/pester/win11creator.Tests.ps1
index 5fee297c..1c7d0c26 100644
--- a/pester/win11creator.Tests.ps1
+++ b/pester/win11creator.Tests.ps1
@@ -3,9 +3,47 @@
 #===========================================================================
 
 Describe "Win11 Creator setup media" {
+    BeforeAll {
+        $script:repoRoot = Resolve-Path (Join-Path $PSScriptRoot "..")
+        $script:isoWorkflowPath = Join-Path $script:repoRoot "functions\private\Invoke-WinUtilISO.ps1"
+        $script:isoScriptPath = Join-Path $script:repoRoot "functions\private\Invoke-WinUtilISOScript.ps1"
+        $script:autoUnattendPath = Join-Path $script:repoRoot "tools\autounattend.xml"
+
+        function Get-WinUtilFunctionText {
+            param (
+                [Parameter(Mandatory)][string]$Path,
+                [Parameter(Mandatory)][string]$FunctionName
+            )
+
+            $tokens = $null
+            $errors = $null
+            $ast = [System.Management.Automation.Language.Parser]::ParseFile((Resolve-Path $Path), [ref]$tokens, [ref]$errors)
+            if ($errors.Count -gt 0) {
+                throw "Unable to parse $Path`: $($errors[0].Message)"
+            }
+
+            $functionAst = $ast.Find({
+                param($node)
+                $node -is [System.Management.Automation.Language.FunctionDefinitionAst] -and
+                    $node.Name -eq $FunctionName
+            }, $true)
+
+            if (-not $functionAst) {
+                throw "Unable to find function $FunctionName in $Path."
+            }
+
+            return $functionAst.Extent.Text
+        }
+
+        $script:editionIdFunction = Get-WinUtilFunctionText -Path $script:isoWorkflowPath -FunctionName "Get-WinUtilEditionIdFromName"
+        $script:addDriversFunction = Get-WinUtilFunctionText -Path $script:isoScriptPath -FunctionName "Add-DriversToImage"
+        $script:answerFileChildElementFunction = Get-WinUtilFunctionText -Path $script:isoScriptPath -FunctionName "Get-WinUtilISOScriptChildElement"
+        $script:answerFileConversionFunction = Get-WinUtilFunctionText -Path $script:isoScriptPath -FunctionName "ConvertTo-WinUtilISOAnswerFile"
+        $script:editionConfigFunction = Get-WinUtilFunctionText -Path $script:isoScriptPath -FunctionName "Write-WinUtilISOEditionConfig"
+    }
+
     It "autounattend template does not force a product key" {
-        $templatePath = Join-Path $PSScriptRoot "..\tools\autounattend.xml"
-        [xml]$xml = Get-Content -Path $templatePath -Raw
+        [xml]$xml = Get-Content -Path $script:autoUnattendPath -Raw
         $nsMgr = New-Object System.Xml.XmlNamespaceManager($xml.NameTable)
         $nsMgr.AddNamespace("u", "urn:schemas-microsoft-com:unattend")
 
@@ -30,4 +68,167 @@ Describe "Win11 Creator setup media" {
             }
         }
     }
+
+    It "maps Windows edition names to setup edition IDs" {
+        . ([scriptblock]::Create($script:editionIdFunction))
+
+        $cases = @{
+            "Windows 11 Home Single Language" = "CoreSingleLanguage"
+            "Windows 11 Home N"               = "CoreN"
+            "Windows 11 Home"                 = "Core"
+            "Windows 11 Pro for Workstations N" = "ProfessionalWorkstationN"
+            "Windows 11 Pro for Workstations" = "ProfessionalWorkstation"
+            "Windows 11 Pro Education N"      = "ProfessionalEducationN"
+            "Windows 11 Pro Education"        = "ProfessionalEducation"
+            "Windows 11 Pro N"                = "ProfessionalN"
+            "Windows 11 Pro"                  = "Professional"
+            "Windows 11 Education N"          = "EducationN"
+            "Windows 11 Education"            = "Education"
+            "Windows 11 Enterprise LTSC N"    = "EnterpriseSN"
+            "Windows 11 Enterprise LTSC"      = "EnterpriseS"
+            "Windows 11 Enterprise N"         = "EnterpriseN"
+            "Windows 11 Enterprise"           = "Enterprise"
+        }
+
+        foreach ($case in $cases.GetEnumerator()) {
+            Get-WinUtilEditionIdFromName -EditionName $case.Key | Should -Be $case.Value
+        }
+
+        Get-WinUtilEditionIdFromName -EditionName "Windows 11 Unknown Edition" | Should -Be ""
+    }
+
+    It "writes ei.cfg and removes stale PID.txt for selected editions" {
+        . ([scriptblock]::Create($script:editionConfigFunction))
+
+        $contentRoot = Join-Path ([IO.Path]::GetTempPath()) "WinUtilIsoConfig_$([guid]::NewGuid())"
+        $sourcesDir = Join-Path $contentRoot "sources"
+        $logs = [System.Collections.Generic.List[string]]::new()
+        $logger = { param($message) $logs.Add([string]$message) }
+
+        try {
+            New-Item -Path $sourcesDir -ItemType Directory -Force | Out-Null
+            Set-Content -Path (Join-Path $sourcesDir "PID.txt") -Value "stale-key" -Encoding UTF8
+
+            Write-WinUtilISOEditionConfig -ContentRoot $contentRoot -EditionId "Professional" -Logger $logger
+
+            Test-Path (Join-Path $sourcesDir "PID.txt") | Should -BeFalse
+            Test-Path (Join-Path $sourcesDir "ei.cfg") | Should -BeTrue
+            (Get-Content -Path (Join-Path $sourcesDir "ei.cfg")) -join "|" |
+                Should -Be "[EditionID]|Professional|[Channel]|Retail|[VL]|0"
+            ($logs -join "|") | Should -Match "Removed sources\\PID\.txt"
+            ($logs -join "|") | Should -Match "Written sources\\ei\.cfg"
+        } finally {
+            Remove-Item -Path $contentRoot -Recurse -Force -ErrorAction SilentlyContinue
+        }
+    }
+
+    It "skips ei.cfg when selected edition ID is unknown" {
+        . ([scriptblock]::Create($script:editionConfigFunction))
+
+        $contentRoot = Join-Path ([IO.Path]::GetTempPath()) "WinUtilIsoConfig_$([guid]::NewGuid())"
+        $logs = [System.Collections.Generic.List[string]]::new()
+        $logger = { param($message) $logs.Add([string]$message) }
+
+        try {
+            New-Item -Path $contentRoot -ItemType Directory -Force | Out-Null
+
+            Write-WinUtilISOEditionConfig -ContentRoot $contentRoot -EditionId "" -Logger $logger
+
+            Test-Path (Join-Path $contentRoot "sources\ei.cfg") | Should -BeFalse
+            ($logs -join "|") | Should -Match "selected edition ID is unknown"
+        } finally {
+            Remove-Item -Path $contentRoot -Recurse -Force -ErrorAction SilentlyContinue
+        }
+    }
+
+    It "converts autounattend setup metadata without preserving placeholder product keys" {
+        . ([scriptblock]::Create($script:answerFileChildElementFunction))
+        . ([scriptblock]::Create($script:answerFileConversionFunction))
+
+        [xml]$templateXml = Get-Content -Path $script:autoUnattendPath -Raw
+        $unattendNs = "urn:schemas-microsoft-com:unattend"
+        $nsMgr = New-Object System.Xml.XmlNamespaceManager($templateXml.NameTable)
+        $nsMgr.AddNamespace("u", $unattendNs)
+        $nsMgr.AddNamespace("sg", "https://schneegans.de/windows/unattend-generator/")
+
+        $setupComponent = $templateXml.SelectSingleNode('//u:settings[@pass="windowsPE"]/u:component[@name="Microsoft-Windows-Setup"]', $nsMgr)
+        $userData = $templateXml.CreateElement("UserData", $unattendNs)
+        $productKey = $templateXml.CreateElement("ProductKey", $unattendNs)
+        $key = $templateXml.CreateElement("Key", $unattendNs)
+        $key.InnerText = "00000-00000-00000-00000-00000"
+        [void]$productKey.AppendChild($key)
+        [void]$userData.AppendChild($productKey)
+        [void]$setupComponent.AppendChild($userData)
+
+        $originalSetupFileCount = $templateXml.SelectNodes("//sg:File", $nsMgr).Count
+        [xml]$converted = ConvertTo-WinUtilISOAnswerFile -XmlContent $templateXml.OuterXml -ImageIndex 3
+        $convertedNsMgr = New-Object System.Xml.XmlNamespaceManager($converted.NameTable)
+        $convertedNsMgr.AddNamespace("u", $unattendNs)
+        $convertedNsMgr.AddNamespace("sg", "https://schneegans.de/windows/unattend-generator/")
+
+        $converted.DocumentElement.NamespaceURI | Should -Be $unattendNs
+        $converted.DocumentElement.GetAttribute("xmlns:wcm") | Should -Be "http://schemas.microsoft.com/WMIConfig/2002/State"
+        $converted.SelectNodes('//u:component[@name="Microsoft-Windows-Setup"]/u:UserData/u:ProductKey', $convertedNsMgr).Count | Should -Be 0
+        $converted.SelectSingleNode('//u:ImageInstall/u:OSImage/u:InstallFrom/u:MetaData[u:Key="/IMAGE/INDEX"]/u:Value', $convertedNsMgr).InnerText | Should -Be "3"
+        $converted.SelectNodes("//sg:File", $convertedNsMgr).Count | Should -Be $originalSetupFileCount
+    }
+
+    It "logs DISM output for driver injection through a mocked command" {
+        . ([scriptblock]::Create($script:addDriversFunction))
+
+        $script:dismArguments = @()
+        function dism {
+            param([Parameter(ValueFromRemainingArguments)]$Arguments)
+            $script:dismArguments = @($Arguments)
+            "driver one"
+            "driver two"
+        }
+
+        $logs = [System.Collections.Generic.List[string]]::new()
+        Add-DriversToImage -MountPath "C:\Mount" -DriverDir "C:\Drivers" -Label "install" -Logger {
+            param($message)
+            $logs.Add([string]$message)
+        }
+
+        ($script:dismArguments -join "|") | Should -Be "/English|/image:C:\Mount|/Add-Driver|/Driver:C:\Drivers|/Recurse"
+        ($logs -join "|") | Should -Be "  dism[install]: driver one|  dism[install]: driver two"
+    }
+
+    It "keeps driver export and boot.wim injection behind the selected branch" {
+        $content = Get-Content -Path $script:isoScriptPath -Raw
+
+        foreach ($expectedText in @(
+            'if ($InjectCurrentSystemDrivers)',
+            'Export-WindowsDriver -Online -Destination $driverExportRoot',
+            'Add-DriversToImage -MountPath $ScratchDir -DriverDir $driverExportRoot -Label "install" -Logger $Log',
+            'Invoke-BootWimInject -BootWimPath $bootWim -DriverDir $driverExportRoot -Logger $Log',
+            'Warning: boot.wim not found - skipping boot.wim driver injection.',
+            'Driver injection skipped.'
+        )) {
+            $content | Should -Match ([regex]::Escape($expectedText))
+        }
+    }
+
+    It "attempts winget oscdimg install and exits before export when fallback fails" {
+        $content = Get-Content -Path $script:isoWorkflowPath -Raw
+
+        foreach ($expectedText in @(
+            'oscdimg.exe not found. Attempting to install via winget...',
+            'Install-WinUtilWinget',
+            'Get-Command winget',
+            'install -e --id Microsoft.OSCDIMG --accept-package-agreements --accept-source-agreements',
+            'oscdimg.exe still not found after install attempt.',
+            'oscdimg Not Found'
+        )) {
+            $content | Should -Match ([regex]::Escape($expectedText))
+        }
+
+        $fallbackIndex = $content.IndexOf('oscdimg.exe not found. Attempting to install via winget...')
+        $notFoundDialogIndex = $content.IndexOf('oscdimg Not Found', $fallbackIndex)
+        $runspaceIndex = $content.IndexOf('[Management.Automation.Runspaces.RunspaceFactory]::CreateRunspace()', $fallbackIndex)
+
+        $fallbackIndex | Should -BeGreaterThan -1
+        $notFoundDialogIndex | Should -BeGreaterThan $fallbackIndex
+        $runspaceIndex | Should -BeGreaterThan $notFoundDialogIndex
+    }
 }
diff --git a/pester/xaml.Tests.ps1 b/pester/xaml.Tests.ps1
new file mode 100644
index 00000000..05e35bf2
--- /dev/null
+++ b/pester/xaml.Tests.ps1
@@ -0,0 +1,404 @@
+#===========================================================================
+# Tests - XAML Control Wiring
+#===========================================================================
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+    $script:configRoot = Join-Path $script:repoRoot "config"
+    $script:functionRoot = Join-Path $script:repoRoot "functions"
+    $script:scriptsRoot = Join-Path $script:repoRoot "scripts"
+    $script:xamlPath = Join-Path $script:repoRoot "xaml\inputXML.xaml"
+    $script:mainScriptPath = Join-Path $script:scriptsRoot "main.ps1"
+    $script:buttonScriptPath = Join-Path $script:functionRoot "public\Invoke-WPFButton.ps1"
+    $script:xamlText = Get-Content -Path $script:xamlPath -Raw
+    $script:xaml = [xml]$script:xamlText
+    $script:xamlNamespace = New-Object System.Xml.XmlNamespaceManager -ArgumentList $script:xaml.NameTable
+    $script:xamlNamespace.AddNamespace("x", "http://schemas.microsoft.com/winfx/2006/xaml")
+
+    function script:Get-WinUtilConfigObject {
+        param([string]$Name)
+
+        Get-Content -Path (Join-Path $script:configRoot "$Name.json") -Raw | ConvertFrom-Json
+    }
+
+    function script:Get-WinUtilSourceText {
+        Get-ChildItem -Path @($script:functionRoot, $script:scriptsRoot) -Filter *.ps1 -Recurse |
+            ForEach-Object { Get-Content -Path $_.FullName -Raw } |
+            Out-String
+    }
+
+    function script:Get-WinUtilTopLevelFunctionNames {
+        Get-ChildItem -Path $script:functionRoot -Filter *.ps1 -Recurse | ForEach-Object {
+            $tokens = $null
+            $syntaxErrors = $null
+            $ast = [System.Management.Automation.Language.Parser]::ParseFile($_.FullName, [ref]$tokens, [ref]$syntaxErrors)
+            if ($syntaxErrors.Count -ne 0) {
+                throw ($syntaxErrors | Out-String)
+            }
+
+            $ast.EndBlock.Statements |
+                Where-Object { $_ -is [System.Management.Automation.Language.FunctionDefinitionAst] } |
+                ForEach-Object { $_.Name }
+        } | Sort-Object -Unique
+    }
+
+    function script:Get-WinUtilXamlNamedControls {
+        $nodes = $script:xaml.SelectNodes("//*[@Name or @x:Name]", $script:xamlNamespace)
+        foreach ($node in $nodes) {
+            $controlName = $node.GetAttribute("Name")
+            if ([string]::IsNullOrWhiteSpace($controlName)) {
+                $controlName = $node.GetAttribute("Name", "http://schemas.microsoft.com/winfx/2006/xaml")
+            }
+
+            [pscustomobject]@{
+                Name = $controlName
+                Type = $node.LocalName
+            }
+        }
+    }
+
+    function script:Get-WinUtilXamlRuntimeNamedControls {
+        $nodes = $script:xaml.SelectNodes("//*[@Name]")
+        foreach ($node in $nodes) {
+            [pscustomobject]@{
+                Name = $node.GetAttribute("Name")
+                Type = $node.LocalName
+            }
+        }
+    }
+
+    function script:Get-WinUtilGeneratedControlNames {
+        $names = New-Object System.Collections.Generic.List[string]
+        foreach ($configName in @("appnavigation", "tweaks", "feature", "appx")) {
+            $config = Get-WinUtilConfigObject -Name $configName
+            foreach ($entry in $config.PSObject.Properties.Name) {
+                $names.Add($entry)
+            }
+        }
+
+        $applications = Get-WinUtilConfigObject -Name "applications"
+        foreach ($entry in $applications.PSObject.Properties.Name) {
+            $names.Add($entry)
+            $names.Add(($entry -replace "-", "_"))
+        }
+
+        $names | Sort-Object -Unique
+    }
+
+    function script:Get-WinUtilButtonSwitchNames {
+        $buttonSource = Get-Content -Path $script:buttonScriptPath -Raw
+        [regex]::Matches($buttonSource, '"(WPF[A-Za-z0-9_]+)"\s*\{') |
+            ForEach-Object { $_.Groups[1].Value } |
+            Sort-Object -Unique
+    }
+
+    function script:Test-WinUtilNameInSet {
+        param(
+            [Parameter(Mandatory)]
+            [string]$Name,
+
+            [Parameter(Mandatory)]
+            [string[]]$Set
+        )
+
+        foreach ($item in $Set) {
+            if ($item -ieq $Name) {
+                return $true
+            }
+        }
+
+        return $false
+    }
+}
+
+Describe "XAML document" {
+    It "loads inputXML.xaml as a WPF window XML document" {
+        $script:xaml.DocumentElement.LocalName | Should -Be "Window"
+    }
+
+    It "contains expected core controls" {
+        $xamlNames = @(Get-WinUtilXamlRuntimeNamedControls | ForEach-Object { $_.Name })
+        $requiredControls = @(
+            "WPFMainGrid",
+            "NavDockPanel",
+            "GridBesideNavDockPanel",
+            "WPFTabNav",
+            "WPFTab1",
+            "WPFTab2",
+            "WPFTab3",
+            "WPFTab4",
+            "WPFTab5",
+            "WPFTab6",
+            "WPFTab1BT",
+            "WPFTab2BT",
+            "WPFTab3BT",
+            "WPFTab4BT",
+            "WPFTab5BT",
+            "WPFTab6BT",
+            "SearchBar",
+            "SearchBarClearButton",
+            "appscategory",
+            "appspanel",
+            "tweakspanel",
+            "featurespanel",
+            "updatespanel",
+            "appxpanel",
+            "WPFstandard",
+            "WPFminimal",
+            "WPFAdvanced",
+            "WPFClearTweaksSelection",
+            "WPFGetInstalledTweaks",
+            "WPFTweaksbutton",
+            "WPFUndoall",
+            "WPFUpdatesdefault",
+            "WPFUpdatessecurity",
+            "WPFUpdatesdisable",
+            "WPFDefaultAppxSelection",
+            "WPFGetInstalledAppx",
+            "WPFSelectAllAppx",
+            "WPFClearAppxSelection",
+            "WPFRemoveSelectedAppx"
+        )
+
+        $missingControls = @($requiredControls | Where-Object { -not (Test-WinUtilNameInSet -Name $_ -Set $xamlNames) })
+        if ($missingControls.Count -gt 0) {
+            throw ($missingControls -join "`n")
+        }
+    }
+
+    It "contains Win11 Creator controls used by the ISO workflow" {
+        $xamlNames = @(Get-WinUtilXamlRuntimeNamedControls | ForEach-Object { $_.Name })
+        $requiredControls = @(
+            "Win11ISOPanel",
+            "WPFWin11ISOSelectSection",
+            "WPFWin11ISOPath",
+            "WPFWin11ISOBrowseButton",
+            "WPFWin11ISOFileInfo",
+            "WPFWin11ISODownloadLink",
+            "WPFWin11ISOMountSection",
+            "WPFWin11ISOMountButton",
+            "WPFWin11ISOInjectDrivers",
+            "WPFWin11ISOVerifyResultPanel",
+            "WPFWin11ISOMountDriveLetter",
+            "WPFWin11ISOArchLabel",
+            "WPFWin11ISOEditionComboBox",
+            "WPFWin11ISOModifySection",
+            "WPFWin11ISOModifyButton",
+            "WPFWin11ISOOutputSection",
+            "WPFWin11ISOCleanResetButton",
+            "WPFWin11ISOChooseISOButton",
+            "WPFWin11ISOChooseUSBButton",
+            "WPFWin11ISOOptionUSB",
+            "WPFWin11ISOUSBDriveComboBox",
+            "WPFWin11ISORefreshUSBButton",
+            "WPFWin11ISOWriteUSBButton",
+            "WPFWin11ISOStatusLog"
+        )
+
+        $missingControls = @($requiredControls | Where-Object { -not (Test-WinUtilNameInSet -Name $_ -Set $xamlNames) })
+        if ($missingControls.Count -gt 0) {
+            throw ($missingControls -join "`n")
+        }
+    }
+
+    It "defines core tabs in the expected order" {
+        $tabItems = @($script:xaml.SelectNodes('//*[local-name()="TabControl"][@Name="WPFTabNav"]/*[local-name()="TabItem"]'))
+        $actualTabs = @($tabItems | ForEach-Object { "$($_.GetAttribute("Name")):$($_.GetAttribute("Header"))" })
+        $expectedTabs = @(
+            "WPFTab1:Install",
+            "WPFTab2:Tweaks",
+            "WPFTab3:Config",
+            "WPFTab4:Updates",
+            "WPFTab5:Win11ISO",
+            "WPFTab6:AppX"
+        )
+
+        if (@($actualTabs).Count -ne $expectedTabs.Count) {
+            throw "Expected $($expectedTabs.Count) tabs but found $(@($actualTabs).Count): $($actualTabs -join ', ')"
+        }
+
+        for ($index = 0; $index -lt $expectedTabs.Count; $index++) {
+            if ($actualTabs[$index] -ne $expectedTabs[$index]) {
+                throw "Tab order mismatch at index ${index}: expected $($expectedTabs[$index]), found $($actualTabs[$index])"
+            }
+        }
+    }
+}
+
+Describe "XAML and sync wiring" {
+    It "wires generated config panels to existing target grids" {
+        $xamlNames = @(Get-WinUtilXamlRuntimeNamedControls | ForEach-Object { $_.Name })
+        $mainLines = Get-Content -Path $script:mainScriptPath
+        $invalidTargets = New-Object System.Collections.Generic.List[string]
+
+        foreach ($line in $mainLines) {
+            if ($line.TrimStart().StartsWith("#")) {
+                continue
+            }
+
+            $match = [regex]::Match(
+                $line,
+                'Invoke-WPFUIElements\s+-configVariable\s+\$sync\.configs\.([A-Za-z0-9_]+)\s+-targetGridName\s+"([^"]+)"'
+            )
+            if (-not $match.Success) {
+                continue
+            }
+
+            $configName = $match.Groups[1].Value
+            $targetGridName = $match.Groups[2].Value
+            if (-not (Test-Path -Path (Join-Path $script:configRoot "$configName.json"))) {
+                $invalidTargets.Add("$configName references missing config file")
+            }
+
+            if (-not (Test-WinUtilNameInSet -Name $targetGridName -Set $xamlNames)) {
+                $invalidTargets.Add("$configName target grid '$targetGridName' was not found in XAML")
+            }
+        }
+
+        if ($invalidTargets.Count -gt 0) {
+            throw ($invalidTargets -join "`n")
+        }
+    }
+
+    It "references only XAML, generated, or intentionally dynamic sync members" {
+        $sourceText = Get-WinUtilSourceText
+        $xamlNames = @(Get-WinUtilXamlRuntimeNamedControls | ForEach-Object { $_.Name })
+        $generatedNames = @(Get-WinUtilGeneratedControlNames)
+        $dynamicStateNames = @(
+            "Form",
+            "configs",
+            "preferences",
+            "runspace",
+            "Buttons",
+            "PSScriptRoot",
+            "version",
+            "winutildir",
+            "logPath",
+            "transcriptPath",
+            "ProcessRunning",
+            "selected",
+            "selectedAppx",
+            "selectedApps",
+            "selectedTweaks",
+            "selectedToggles",
+            "selectedFeatures",
+            "currentTab",
+            "selectedAppsStackPanel",
+            "selectedAppsstackPanel",
+            "selectedAppsPopup",
+            "appPopup",
+            "appPopupSelectedApp",
+            "ItemsControl",
+            "InstalledPrograms",
+            "ImportInProgress",
+            "ScriptsInstallPrograms",
+            "keys",
+            "ContainsKey",
+            "GetEnumerator",
+            "logorender",
+            "checkmarkrender",
+            "warningrender",
+            "InstallAppAreaBorder",
+            "InstallAppAreaScrollViewer",
+            "InstallAppAreaOverlay",
+            "InstallAppAreaOverlayText",
+            "ProgressBar",
+            "progressBarTextBlock",
+            "Win11ISOImageInfo",
+            "Win11ISODriveLetter",
+            "Win11ISOWimPath",
+            "Win11ISOImagePath",
+            "Win11ISOModifying",
+            "Win11ISOWorkDir",
+            "Win11ISOContentsDir",
+            "Win11ISOUSBDisks"
+        )
+        $allowedNames = @($xamlNames + $generatedNames + $dynamicStateNames) | Sort-Object -Unique
+        $bracketReferences = @(
+            [regex]::Matches($sourceText, '\$sync\[\s*["'']([A-Za-z_][A-Za-z0-9_]*)["'']\s*\]') |
+                ForEach-Object { $_.Groups[1].Value }
+        )
+        $dotReferences = @(
+            [regex]::Matches($sourceText, '\$sync\.([A-Za-z_][A-Za-z0-9_]*)') |
+                ForEach-Object { $_.Groups[1].Value }
+        )
+        $literalReferences = @($bracketReferences + $dotReferences) | Sort-Object -Unique
+
+        $invalidReferences = @(
+            $literalReferences | Where-Object { -not (Test-WinUtilNameInSet -Name $_ -Set $allowedNames) }
+        )
+        if ($invalidReferences.Count -gt 0) {
+            throw ($invalidReferences -join "`n")
+        }
+    }
+}
+
+Describe "WPF handler wiring" {
+    It "calls only defined Invoke-WPF functions" {
+        $sourceText = Get-WinUtilSourceText
+        $functionNames = @(Get-WinUtilTopLevelFunctionNames)
+        $featureFunctions = @(
+            (Get-WinUtilConfigObject -Name "feature").PSObject.Properties |
+                Where-Object { $_.Value.function -and $_.Value.function -like "Invoke-WPF*" } |
+                ForEach-Object { $_.Value.function }
+        )
+        $invokedFunctions = @(
+            [regex]::Matches($sourceText, '\b(Invoke-WPF[A-Za-z0-9]+)\b') |
+                ForEach-Object { $_.Groups[1].Value }
+            $featureFunctions
+        ) | Sort-Object -Unique
+
+        $missingFunctions = @(
+            $invokedFunctions | Where-Object { -not (Test-WinUtilNameInSet -Name $_ -Set $functionNames) }
+        )
+        if ($missingFunctions.Count -gt 0) {
+            throw ($missingFunctions -join "`n")
+        }
+    }
+
+    It "routes static WPF buttons through Invoke-WPFButton or explicit handlers" {
+        $runtimeControls = @(Get-WinUtilXamlRuntimeNamedControls)
+        $buttonControls = @(
+            $runtimeControls |
+                Where-Object { $_.Name -like "WPF*" -and $_.Type -in @("Button", "ToggleButton") }
+        )
+        $buttonSwitchNames = @(Get-WinUtilButtonSwitchNames)
+        $featureNames = @((Get-WinUtilConfigObject -Name "feature").PSObject.Properties.Name)
+        $mainScript = Get-Content -Path $script:mainScriptPath -Raw
+        $unhandledButtons = New-Object System.Collections.Generic.List[string]
+
+        foreach ($button in $buttonControls) {
+            $hasSwitchHandler = (Test-WinUtilNameInSet -Name $button.Name -Set $buttonSwitchNames) -or $button.Name -like "WPFTab?BT"
+            $hasFeatureHandler = Test-WinUtilNameInSet -Name $button.Name -Set $featureNames
+            $escapedName = [regex]::Escape($button.Name)
+            $explicitHandlerPattern = '\$sync\s*(?:\[\s*["'']' + $escapedName + '["'']\s*\]|\.' + $escapedName + ')\.Add_Click'
+            $hasExplicitHandler = $mainScript -imatch $explicitHandlerPattern
+
+            if (-not ($hasSwitchHandler -or $hasFeatureHandler -or $hasExplicitHandler)) {
+                $unhandledButtons.Add($button.Name)
+            }
+        }
+
+        if ($unhandledButtons.Count -gt 0) {
+            throw ($unhandledButtons -join "`n")
+        }
+    }
+
+    It "invokes existing WPF button names" {
+        $sourceText = Get-WinUtilSourceText
+        $xamlNames = @(Get-WinUtilXamlRuntimeNamedControls | ForEach-Object { $_.Name })
+        $generatedNames = @(Get-WinUtilGeneratedControlNames)
+        $validButtonNames = @($xamlNames + $generatedNames) | Sort-Object -Unique
+        $buttonNames = @(
+            [regex]::Matches($sourceText, 'Invoke-WPFButton\s+["'']([^"'']+)["'']') |
+                ForEach-Object { $_.Groups[1].Value }
+        ) | Sort-Object -Unique
+
+        $missingButtons = @(
+            $buttonNames | Where-Object { -not (Test-WinUtilNameInSet -Name $_ -Set $validButtonNames) }
+        )
+        if ($missingButtons.Count -gt 0) {
+            throw ($missingButtons -join "`n")
+        }
+    }
+}
diff --git a/scripts/start.ps1 b/scripts/start.ps1
index e689b493..25e82580 100644
--- a/scripts/start.ps1
+++ b/scripts/start.ps1
@@ -81,10 +81,13 @@ $dateTime = Get-Date -Format "yyyy-MM-dd_HH-mm-ss"
 # Set the path for the winutil directory
 $winutildir = "$env:LocalAppData\winutil"
 New-Item $winutildir -ItemType Directory -Force | Out-Null
+$sync.winutildir = $winutildir
 
 $logdir = "$winutildir\logs"
 New-Item $logdir -ItemType Directory -Force | Out-Null
-Start-Transcript -Path "$logdir\winutil_$dateTime.log" -Append -NoClobber | Out-Null
+$sync.logPath = "$logdir\winutil_$dateTime.log"
+$sync.transcriptPath = $sync.logPath
+Start-Transcript -Path $sync.logPath -Append -NoClobber | Out-Null
 
 # Set PowerShell window title
 $Host.UI.RawUI.WindowTitle = "WinUtil (Admin)"