Fix deferred install render timer callback

functions/private/Start-WinUtilInstallAppRendering.ps1

@@ -1,3 +1,18 @@
+function Invoke-WinUtilInstallAppRenderBatch {
+    param(
+        [Parameter(Mandatory = $true)]
+        $CategoryBatch
+    )
+
+    foreach ($appKey in $CategoryBatch.AppKeys) {
+        $sync.$appKey = Initialize-InstallAppEntry -TargetElement $CategoryBatch.TargetElement -AppKey $appKey
+    }
+
+    if ($sync.currentTab -eq "Install" -and $sync.SearchBar -and -not [string]::IsNullOrWhiteSpace($sync.SearchBar.Text)) {
+        Find-AppsByNameOrDescription -SearchString $sync.SearchBar.Text
+    }
+}
+
 function Start-WinUtilInstallAppRendering {
     if ($null -eq $sync.InstallAppRenderQueue) {
         return
@@ -5,31 +20,22 @@ function Start-WinUtilInstallAppRendering {
 
     $sync.InstallAppEntriesRendered = $false
 
-    $renderCategory = {
-        param($CategoryBatch)
-
-        foreach ($appKey in $CategoryBatch.AppKeys) {
-            $sync.$appKey = Initialize-InstallAppEntry -TargetElement $CategoryBatch.TargetElement -AppKey $appKey
-        }
-
-        if ($sync.currentTab -eq "Install" -and $sync.SearchBar -and -not [string]::IsNullOrWhiteSpace($sync.SearchBar.Text)) {
-            Find-AppsByNameOrDescription -SearchString $sync.SearchBar.Text
-        }
-    }
-
     if ($sync.Form -and $sync.Form.Dispatcher -and ("System.Windows.Threading.DispatcherTimer" -as [type])) {
         $timer = New-Object System.Windows.Threading.DispatcherTimer
         $timer.Interval = [TimeSpan]::FromMilliseconds(1)
         $timer.Add_Tick({
-            $timer.Stop()
+            param($sender)
+
+            $dispatcherTimer = [System.Windows.Threading.DispatcherTimer]$sender
+            $dispatcherTimer.Stop()
 
             if ($sync.InstallAppRenderQueue.Count -gt 0) {
                 $categoryBatch = $sync.InstallAppRenderQueue.Dequeue()
-                & $renderCategory $categoryBatch
+                Invoke-WinUtilInstallAppRenderBatch -CategoryBatch $categoryBatch
             }
 
             if ($sync.InstallAppRenderQueue.Count -gt 0) {
-                $timer.Start()
+                $dispatcherTimer.Start()
                 return
             }
 
@@ -43,7 +49,7 @@ function Start-WinUtilInstallAppRendering {
 
     while ($sync.InstallAppRenderQueue.Count -gt 0) {
         $categoryBatch = $sync.InstallAppRenderQueue.Dequeue()
-        & $renderCategory $categoryBatch
+        Invoke-WinUtilInstallAppRenderBatch -CategoryBatch $categoryBatch
     }
 
     $sync.InstallAppEntriesRendered = $true

pester/install-rendering.Tests.ps1

@@ -23,6 +23,16 @@ Describe "Install app rendering startup contract" {
         $renderScript | Should -Match 'Install app entries rendered'
     }
 
+    It "does not rely on local timer variables after the dispatcher tick fires" {
+        $renderScript = Get-Content -Path (Join-Path $script:repoRoot "functions\private\Start-WinUtilInstallAppRendering.ps1") -Raw
+
+        $renderScript | Should -Match 'param\(\$sender\)'
+        $renderScript | Should -Match '\$dispatcherTimer = \[System\.Windows\.Threading\.DispatcherTimer\]\$sender'
+        $renderScript | Should -Not -Match '\$timer\.Stop\(\)'
+        $renderScript | Should -Match '\$dispatcherTimer\.Start\(\)'
+        $renderScript | Should -Not -Match '& \$renderCategory'
+    }
+
     It "keeps app-entry metadata lookup independent from the old caller scope" {
         $entryScript = Get-Content -Path (Join-Path $script:repoRoot "functions\private\Initialize-InstallAppEntry.ps1") -Raw