diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index ebad81f..0108969 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -230,6 +230,15 @@ jobs:
             exit 1
           }
 
+      - name: Run GUI app selection tests
+        shell: pwsh
+        run: |
+          $result = Invoke-Pester -Path "Tests/Unit/Test-GuiAppSelection.ps1" -Output Detailed -PassThru
+          if ($result.FailedCount -gt 0) {
+            Write-Error "$($result.FailedCount) test(s) failed in Test-GuiAppSelection.ps1"
+            exit 1
+          }
+
       - name: Run Store search suggestion tests
         shell: pwsh
         run: |
diff --git a/Tests/Unit/Test-GuiAppSelection.ps1 b/Tests/Unit/Test-GuiAppSelection.ps1
new file mode 100644
index 0000000..24464e0
--- /dev/null
+++ b/Tests/Unit/Test-GuiAppSelection.ps1
@@ -0,0 +1,300 @@
+#Requires -Modules Pester
+<#
+.SYNOPSIS
+    Unit tests for the app-selection panel helpers that operate on live WPF
+    controls but not on a fully built window.
+.DESCRIPTION
+    Update-AppRemovalScopeDescription, Update-AppSelectionStatus,
+    Update-AppsPanelRebuildSearchIndex, Update-SortArrows, Update-AppsPanelSort
+    and Invoke-AppPreset take real panels, checkboxes, combo boxes and text
+    blocks. Each scenario builds the controls, drives the function, and returns
+    the resulting state.
+
+    WPF construction needs a single-threaded apartment; the unit suite runs
+    under pwsh (MTA), so every scenario runs in its own STA runspace. The
+    runspace shares this process, so the returned values are real.
+
+    Invoke-AppPreset delegates its checkbox summary to Update-AppPresetStates,
+    which reaches into the main window via FindName. The scenario overrides that
+    collaborator with a stub after dot-sourcing so the preset check/uncheck
+    logic can be exercised without a built window; the window-bound helpers
+    (Update-AppPresetStates, the scroll helpers) are covered by the Sandbox
+    smoke run, not here.
+#>
+
+BeforeAll {
+    $script:repoRoot = Resolve-Path (Join-Path $PSScriptRoot '..\..') | Select-Object -ExpandProperty Path
+
+    function Invoke-InStaRunspace {
+        param(
+            [Parameter(Mandatory)][scriptblock]$Script,
+            [object[]]$ArgumentList = @()
+        )
+        $runspace = [runspacefactory]::CreateRunspace()
+        $runspace.ApartmentState = 'STA'
+        $runspace.ThreadOptions = 'ReuseThread'
+        $runspace.Open()
+        try {
+            $shell = [powershell]::Create()
+            $shell.Runspace = $runspace
+            [void]$shell.AddScript($Script.ToString())
+            foreach ($argument in $ArgumentList) { [void]$shell.AddArgument($argument) }
+            $output = $shell.Invoke()
+            if ($shell.HadErrors) {
+                throw (($shell.Streams.Error | ForEach-Object { $_.ToString() }) -join '; ')
+            }
+            $shell.Dispose()
+            return $output[-1]
+        }
+        finally {
+            $runspace.Dispose()
+        }
+    }
+
+    $script:scopeDescriptionScenario = {
+        param($repoRoot, $itemContent)
+        Add-Type -AssemblyName PresentationFramework, PresentationCore, WindowsBase -ErrorAction Stop
+        . (Join-Path $repoRoot 'Scripts\GUI\MainWindow-AppSelection.ps1')
+
+        $combo = New-Object System.Windows.Controls.ComboBox
+        foreach ($text in 'All users', 'Current user only', 'Target user only') {
+            $item = New-Object System.Windows.Controls.ComboBoxItem
+            $item.Content = $text
+            [void]$combo.Items.Add($item)
+            if ($text -eq $itemContent) { $combo.SelectedItem = $item }
+        }
+        $desc = New-Object System.Windows.Controls.TextBlock
+        Update-AppRemovalScopeDescription -AppRemovalScopeCombo $combo -AppRemovalScopeDescription $desc
+        return @{ Text = $desc.Text }
+    }
+
+    $script:selectionStatusScenario = {
+        param($repoRoot, $checkedCount, $userComboIndex)
+        Add-Type -AssemblyName PresentationFramework, PresentationCore, WindowsBase -ErrorAction Stop
+        . (Join-Path $repoRoot 'Scripts\GUI\MainWindow-AppSelection.ps1')
+
+        $panel = New-Object System.Windows.Controls.StackPanel
+        for ($i = 0; $i -lt 3; $i++) {
+            $cb = New-Object System.Windows.Controls.CheckBox
+            $cb.IsChecked = ($i -lt $checkedCount)
+            [void]$panel.Children.Add($cb)
+        }
+
+        $status = New-Object System.Windows.Controls.TextBlock
+        $scopeCombo = New-Object System.Windows.Controls.ComboBox
+        $allUsers = New-Object System.Windows.Controls.ComboBoxItem
+        $allUsers.Content = 'All users'
+        [void]$scopeCombo.Items.Add($allUsers)
+        $scopeCombo.SelectedItem = $allUsers
+        $scopeCombo.IsEnabled = $false
+        $scopeSection = New-Object System.Windows.Controls.Border
+        $scopeSection.Visibility = 'Collapsed'
+        $scopeDesc = New-Object System.Windows.Controls.TextBlock
+        $userCombo = New-Object System.Windows.Controls.ComboBox
+        foreach ($u in 'a', 'b', 'c') {
+            $ui = New-Object System.Windows.Controls.ComboBoxItem
+            $ui.Content = $u
+            [void]$userCombo.Items.Add($ui)
+        }
+        $userCombo.SelectedIndex = $userComboIndex
+
+        Update-AppSelectionStatus -AppsPanel $panel -AppSelectionStatus $status `
+            -AppRemovalScopeCombo $scopeCombo -AppRemovalScopeSection $scopeSection `
+            -AppRemovalScopeDescription $scopeDesc -UserSelectionCombo $userCombo
+
+        return @{
+            StatusText  = $status.Text
+            Visibility  = $scopeSection.Visibility.ToString()
+            ScopeEnabled = $scopeCombo.IsEnabled
+        }
+    }
+
+    $script:searchIndexScenario = {
+        param($repoRoot, $case)
+        Add-Type -AssemblyName PresentationFramework, PresentationCore, WindowsBase -ErrorAction Stop
+        . (Join-Path $repoRoot 'Scripts\GUI\MainWindow-AppSelection.ps1')
+
+        $panel = New-Object System.Windows.Controls.StackPanel
+        # Two highlighted (match) checkboxes with a plain one between them, plus a
+        # non-checkbox child that must be ignored.
+        $match1 = New-Object System.Windows.Controls.CheckBox
+        $match1.Background = [System.Windows.Media.Brushes]::Yellow
+        $plain = New-Object System.Windows.Controls.CheckBox
+        $plain.Background = [System.Windows.Media.Brushes]::Transparent
+        $match2 = New-Object System.Windows.Controls.CheckBox
+        $match2.Background = [System.Windows.Media.Brushes]::Yellow
+        [void]$panel.Children.Add($match1)
+        [void]$panel.Children.Add((New-Object System.Windows.Controls.TextBlock))
+        [void]$panel.Children.Add($plain)
+        [void]$panel.Children.Add($match2)
+
+        $active = if ($case -eq 'active-second') { $match2 } else { $null }
+        Update-AppsPanelRebuildSearchIndex -AppsPanel $panel -ActiveMatch $active
+
+        return @{ MatchCount = $script:AppSearchMatches.Count; Index = $script:AppSearchMatchIndex }
+    }
+
+    $script:sortArrowsScenario = {
+        param($repoRoot, $column, $ascending)
+        Add-Type -AssemblyName PresentationFramework, PresentationCore, WindowsBase -ErrorAction Stop
+        . (Join-Path $repoRoot 'Scripts\GUI\MainWindow-AppSelection.ps1')
+
+        function New-Arrow {
+            $tb = New-Object System.Windows.Controls.TextBlock
+            $tb.RenderTransform = New-Object System.Windows.Media.RotateTransform
+            return $tb
+        }
+        $name = New-Arrow; $descr = New-Arrow; $appId = New-Arrow
+        $script:SortColumn = $column
+        $script:SortAscending = [bool]$ascending
+
+        Update-SortArrows -SortArrowName $name -SortArrowDescription $descr -SortArrowAppId $appId
+        return @{ Name = $name.Opacity; Description = $descr.Opacity; AppId = $appId.Opacity }
+    }
+
+    $script:sortScenario = {
+        param($repoRoot, $ascending)
+        Add-Type -AssemblyName PresentationFramework, PresentationCore, WindowsBase -ErrorAction Stop
+        . (Join-Path $repoRoot 'Scripts\GUI\MainWindow-AppSelection.ps1')
+
+        $panel = New-Object System.Windows.Controls.StackPanel
+        foreach ($n in 'Charlie', 'Alpha', 'Bravo') {
+            $cb = New-Object System.Windows.Controls.CheckBox
+            $cb | Add-Member -NotePropertyName AppName -NotePropertyValue $n -Force
+            $cb | Add-Member -NotePropertyName AppDescription -NotePropertyValue $n -Force
+            $cb | Add-Member -NotePropertyName AppIdDisplay -NotePropertyValue $n -Force
+            [void]$panel.Children.Add($cb)
+        }
+
+        function New-PanelSortArrow {
+            $tb = New-Object System.Windows.Controls.TextBlock
+            $tb.RenderTransform = New-Object System.Windows.Media.RotateTransform
+            return $tb
+        }
+        $script:SortColumn = 'Name'
+        $script:SortAscending = [bool]$ascending
+        $script:AppSearchMatches = @()
+        $script:AppSearchMatchIndex = -1
+
+        Update-AppsPanelSort -AppsPanel $panel -SortArrowName (New-PanelSortArrow) -SortArrowDescription (New-PanelSortArrow) -SortArrowAppId (New-PanelSortArrow)
+        return @{ Order = (@($panel.Children) | ForEach-Object { $_.AppName }) -join ',' }
+    }
+
+    $script:presetScenario = {
+        param($repoRoot, $mode)
+        Add-Type -AssemblyName PresentationFramework, PresentationCore, WindowsBase -ErrorAction Stop
+        . (Join-Path $repoRoot 'Scripts\GUI\MainWindow-AppSelection.ps1')
+        # Override the window-bound summary collaborator so only the preset
+        # check/uncheck logic runs.
+        function Update-AppPresetStates { param($AppsPanel) }
+
+        $panel = New-Object System.Windows.Controls.StackPanel
+        foreach ($spec in @(@{ Tag = 'x'; Pre = $false }, @{ Tag = 'y'; Pre = $true }, @{ Tag = 'x'; Pre = $false })) {
+            $cb = New-Object System.Windows.Controls.CheckBox
+            $cb.Tag = $spec.Tag
+            $cb.IsChecked = $spec.Pre
+            [void]$panel.Children.Add($cb)
+        }
+        $filter = { param($c) $c.Tag -eq 'x' }
+
+        if ($mode -eq 'exclusive') {
+            Invoke-AppPreset -AppsPanel $panel -MatchFilter $filter -Check $true -Exclusive
+        }
+        else {
+            Invoke-AppPreset -AppsPanel $panel -MatchFilter $filter -Check $true
+        }
+
+        $states = @($panel.Children | ForEach-Object { [bool]$_.IsChecked })
+        return @{ First = $states[0]; Second = $states[1]; Third = $states[2] }
+    }
+}
+
+Describe 'Update-AppRemovalScopeDescription' {
+    It 'sets the all-users copy, mentioning the image, for the all-users scope' {
+        $r = Invoke-InStaRunspace -Script $script:scopeDescriptionScenario -ArgumentList @($script:repoRoot, 'All users')
+        $r.Text | Should -Match 'all users'
+        $r.Text | Should -Match 'image'
+    }
+
+    It 'sets the current-user copy' {
+        $r = Invoke-InStaRunspace -Script $script:scopeDescriptionScenario -ArgumentList @($script:repoRoot, 'Current user only')
+        $r.Text | Should -Match 'current user'
+    }
+
+    It 'sets the target-user copy' {
+        $r = Invoke-InStaRunspace -Script $script:scopeDescriptionScenario -ArgumentList @($script:repoRoot, 'Target user only')
+        $r.Text | Should -Match 'target user'
+    }
+}
+
+Describe 'Update-AppSelectionStatus' {
+    It 'reports the count and reveals the scope section when apps are selected' {
+        $r = Invoke-InStaRunspace -Script $script:selectionStatusScenario -ArgumentList @($script:repoRoot, 2, 0)
+        $r.StatusText | Should -Be '2 app(s) selected for removal'
+        $r.Visibility | Should -Be 'Visible'
+        $r.ScopeEnabled | Should -BeTrue
+    }
+
+    It 'collapses the scope section when nothing is selected' {
+        $r = Invoke-InStaRunspace -Script $script:selectionStatusScenario -ArgumentList @($script:repoRoot, 0, 0)
+        $r.StatusText | Should -Be '0 app(s) selected for removal'
+        $r.Visibility | Should -Be 'Collapsed'
+    }
+
+    It 'leaves the scope combo disabled while the target-user option is selected' {
+        $r = Invoke-InStaRunspace -Script $script:selectionStatusScenario -ArgumentList @($script:repoRoot, 2, 2)
+        $r.Visibility | Should -Be 'Visible'
+        $r.ScopeEnabled | Should -BeFalse
+    }
+}
+
+Describe 'Update-AppsPanelRebuildSearchIndex' {
+    It 'indexes only the highlighted checkboxes and skips other children' {
+        $r = Invoke-InStaRunspace -Script $script:searchIndexScenario -ArgumentList @($script:repoRoot, 'none')
+        $r.MatchCount | Should -Be 2
+        $r.Index | Should -Be 0
+    }
+
+    It 'points the active index at the supplied active match' {
+        $r = Invoke-InStaRunspace -Script $script:searchIndexScenario -ArgumentList @($script:repoRoot, 'active-second')
+        $r.MatchCount | Should -Be 2
+        $r.Index | Should -Be 1
+    }
+}
+
+Describe 'Update-SortArrows' {
+    It 'lights the active column and dims the others' {
+        $r = Invoke-InStaRunspace -Script $script:sortArrowsScenario -ArgumentList @($script:repoRoot, 'Name', $true)
+        $r.Name | Should -Be 1.0
+        $r.Description | Should -Be 0.3
+        $r.AppId | Should -Be 0.3
+    }
+}
+
+Describe 'Update-AppsPanelSort' {
+    It 'reorders the panel ascending by the active column' {
+        $r = Invoke-InStaRunspace -Script $script:sortScenario -ArgumentList @($script:repoRoot, $true)
+        $r.Order | Should -Be 'Alpha,Bravo,Charlie'
+    }
+
+    It 'reorders the panel descending' {
+        $r = Invoke-InStaRunspace -Script $script:sortScenario -ArgumentList @($script:repoRoot, $false)
+        $r.Order | Should -Be 'Charlie,Bravo,Alpha'
+    }
+}
+
+Describe 'Invoke-AppPreset' {
+    It 'checks only the matching boxes and leaves the rest alone in additive mode' {
+        $r = Invoke-InStaRunspace -Script $script:presetScenario -ArgumentList @($script:repoRoot, 'additive')
+        $r.First | Should -BeTrue
+        $r.Second | Should -BeTrue -Because 'an already-checked non-match is not touched in additive mode'
+        $r.Third | Should -BeTrue
+    }
+
+    It 'checks matches and unchecks non-matches in exclusive mode' {
+        $r = Invoke-InStaRunspace -Script $script:presetScenario -ArgumentList @($script:repoRoot, 'exclusive')
+        $r.First | Should -BeTrue
+        $r.Second | Should -BeFalse -Because 'a non-match is unchecked in exclusive mode'
+        $r.Third | Should -BeTrue
+    }
+}