Add missing docstrings

Scripts/Features/InvokeChanges.ps1

@@ -9,10 +9,6 @@
         - Custom logic: app removal, Windows optional features, start menu
         replacement, and other special-case features.
 #>
-function Test-RunningAsSystem {
-    return ([Security.Principal.WindowsIdentity]::GetCurrent().User.Value -eq 'S-1-5-18')
-}
-
 function Invoke-FeatureApply {
     param(
         [Parameter(Mandatory)]
@@ -433,3 +429,19 @@ function Invoke-AllChanges {
         Write-Host "$($script:RegistryImportFailures) registry import change(s) failed. See output above for details." -ForegroundColor Yellow
     }
 }
+
+<#
+    .SYNOPSIS
+        Tests whether Win11Debloat is running under the SYSTEM account.
+
+    .DESCRIPTION
+        Compares the current Windows identity's security identifier (SID) with
+        the well-known Local System SID (S-1-5-18).
+
+    .OUTPUTS
+        System.Boolean
+        Returns $true when the current process runs as SYSTEM; otherwise, $false.
+#>
+function Test-RunningAsSystem {
+    return ([Security.Principal.WindowsIdentity]::GetCurrent().User.Value -eq 'S-1-5-18')
+}

Scripts/Features/RestoreRegistryApplyState.ps1

@@ -1,3 +1,16 @@
+<#
+    .SYNOPSIS
+        Runs a script block against the registry hive for a backup target.
+
+    .PARAMETER Target
+        A supported backup target: DefaultUserProfile or User:<user name>.
+
+    .PARAMETER ScriptBlock
+        The operation to run after the target user hive is available.
+
+    .PARAMETER ArgumentObject
+        Optional object passed to the script block.
+#>
 function Invoke-WithLoadedRestoreHive {
     param(
         [Parameter(Mandatory)]
@@ -24,6 +37,13 @@ function Invoke-WithLoadedRestoreHive {
     Invoke-WithTargetUserHive -TargetUserName $targetUserName -ScriptBlock $ScriptBlock -ArgumentObject $ArgumentObject
 }
 
+<#
+    .SYNOPSIS
+        Restores a registry key and its child keys from a backup snapshot.
+
+    .PARAMETER Snapshot
+        The saved registry-key state, including existence, values, and subkeys.
+#>
 function Restore-RegistryKeySnapshot {
     param(
         [Parameter(Mandatory)]
@@ -74,6 +94,16 @@ function Restore-RegistryKeySnapshot {
     }
 }
 
+<#
+    .SYNOPSIS
+        Restores or removes a registry value from a backup snapshot.
+
+    .PARAMETER RegistryKey
+        The open registry key that contains the value.
+
+    .PARAMETER Snapshot
+        The saved registry-value state to apply.
+#>
 function Restore-RegistryValueSnapshot {
     param(
         [Parameter(Mandatory)]
@@ -105,6 +135,16 @@ function Restore-RegistryValueSnapshot {
     }
 }
 
+<#
+    .SYNOPSIS
+        Converts a backed-up registry value-kind name to its .NET enum value.
+
+    .PARAMETER KindName
+        The registry value-kind name stored in the backup.
+
+    .OUTPUTS
+        Microsoft.Win32.RegistryValueKind
+#>
 function Convert-RegistryValueKindFromBackup {
     param(
         [string]$KindName
@@ -122,6 +162,16 @@ function Convert-RegistryValueKindFromBackup {
     }
 }
 
+<#
+    .SYNOPSIS
+        Converts backed-up data to a value suitable for registry restoration.
+
+    .PARAMETER Kind
+        The registry value kind that determines how the data is converted.
+
+    .PARAMETER Data
+        The serialized value data from the backup.
+#>
 function Convert-RegistryValueDataFromBackup {
     param(
         [Microsoft.Win32.RegistryValueKind]$Kind,
@@ -162,6 +212,17 @@ function Convert-RegistryValueDataFromBackup {
     }
 }
 
+<#
+    .SYNOPSIS
+        Converts serialized binary backup data to a byte array.
+
+    .PARAMETER Data
+        A byte array or collection of integer byte values from the backup.
+
+    .OUTPUTS
+        System.Byte[]
+        Returns $null when the input contains invalid byte data.
+#>
 function Convert-BackupDataToByteArray {
     param(
         $Data

Scripts/FileIO/LoadAppsDetailsFromJson.ps1

@@ -1,4 +1,26 @@
-# Read Apps.json and return list of app objects with optional filtering
+<#
+    .SYNOPSIS
+        Loads application details from Apps.json.
+
+    .DESCRIPTION
+        Reads the application definitions from Apps.json, optionally filters the
+        results to installed applications, and returns normalized app objects for
+        display and selection.
+
+    .PARAMETER OnlyInstalled
+        Filters the results to applications detected through Appx or the supplied
+        winget installation list.
+
+    .PARAMETER InstalledList
+        A pre-fetched winget installation list used when filtering installed apps.
+
+    .PARAMETER InitialCheckedFromJson
+        Sets each returned app's IsChecked value from its SelectedByDefault setting.
+
+    .OUTPUTS
+        System.Management.Automation.PSCustomObject[]
+        Application detail objects containing display, selection, and removal data.
+#>
 function LoadAppsDetailsFromJson {
     param (
         [switch]$OnlyInstalled,