Optimize installed app detection (#771)

Scripts/FileIO/Import-AppDetailsFromJson.ps1

@@ -37,6 +37,16 @@ function Import-AppDetailsFromJson {
         return $apps
     }
 
+    $installedAppNames = @{}
+    if ($OnlyInstalled) {
+        # Get-AppxPackage is expensive; query it once and use its package names for the catalog lookup.
+        foreach ($installedApp in @(Get-AppxPackage -ErrorAction SilentlyContinue)) {
+            if ($installedApp.Name -is [string]) {
+                $installedAppNames[$installedApp.Name] = $true
+            }
+        }
+    }
+
     foreach ($appData in $jsonContent.Apps) {
         # Handle AppId as array (could be single or multiple IDs)
         $appIdArray = @(
@@ -51,8 +61,7 @@ function Import-AppDetailsFromJson {
         if ($OnlyInstalled) {
             $isInstalled = $false
             foreach ($appId in $appIdArray) {
-                # Check Get-AppxPackage first (fast, no process launch)
-                if (Get-AppxPackage -Name $appId) {
+                if ($installedAppNames.ContainsKey($appId)) {
                     $isInstalled = $true
                     break
                 }

Tests/Settings-And-Apps-FileIO.Tests.ps1

@@ -187,13 +187,14 @@ Describe 'Import-AppDetailsFromJson' {
     }
 
     It 'filters to installed apps using Appx and winget detection' {
-        Mock Get-AppxPackage { param($Name) if ($Name -eq 'Two.App') { [PSCustomObject]@{ Name = $Name } } }
+        Mock Get-AppxPackage { [PSCustomObject]@{ Name = 'Two.App' } }
         Mock Test-AppInWingetList { $false }
 
         $apps = @(Import-AppDetailsFromJson -OnlyInstalled -InstalledList @())
 
         $apps | Should -HaveCount 1
         $apps[0].AppId | Should -Be 'Two.App'
+        Should -Invoke Get-AppxPackage -Times 1 -Exactly
     }
 
     It 'loads presets and preserves their ID arrays' {