Add BITS transfer priority configuration support

Introduces a new parameter to control BITS download priority across the build system and UI, allowing users to optimize transfer speeds when needed.

The feature adds a priority selector to the UI with four options (Foreground, High, Normal, Low) and propagates the selection through the build script and common modules. Priority can be set via UI, command-line parameter, or environment variable, with Normal as the default.

Updates the BITS transfer retry logic to respect the configured priority instead of hardcoding Normal priority, and fixes minor code formatting inconsistencies.

FFUDevelopment/BuildFFUVM.ps1

@@ -354,6 +354,8 @@ param(
     [bool]$BuildUSBDrive,
     [hashtable]$USBDriveList,
     [int]$MaxUSBDrives = 5,
+    [ValidateSet('Foreground', 'High', 'Normal', 'Low')]
+    [string]$BitsPriority = 'Normal',
     [Parameter(Mandatory = $false)]
     [ValidateSet(10, 11, 2016, 2019, 2021, 2022, 2024, 2025)]
     [int]$WindowsRelease = 11,
@@ -659,6 +661,7 @@ if ($WindowsSKU -like "*LTS*") {
 
 # Set the log path for the common logger
 Set-CommonCoreLogPath -Path $LogFile
+Set-BitsTransferPriority -Priority $BitsPriority
 
 #FUNCTIONS
 

FFUDevelopment/BuildFFUVM_UI.xaml

@@ -641,7 +641,7 @@
             <TabItem Header="Build" Padding="20">
                 <ScrollViewer VerticalScrollBarVisibility="Auto">
                     <Grid Margin="10">
-                        <!-- Define 10 rows for the Build tab -->
+                        <!-- Define 12 rows for the Build tab -->
                         <Grid.RowDefinitions>
                             <!-- Row 0: Header -->
                             <RowDefinition Height="Auto"/>
@@ -657,13 +657,15 @@
                             <RowDefinition Height="Auto"/>
                             <!-- Row 6: Threads -->
                             <RowDefinition Height="Auto"/>
-                            <!-- Row 7: General Build Options Header -->
+                            <!-- Row 7: BITS Priority -->
                             <RowDefinition Height="Auto"/>
-                            <!-- Row 8: General Build Options Checkboxes -->
+                            <!-- Row 8: General Build Options Header -->
                             <RowDefinition Height="Auto"/>
-                            <!-- Row 9: Build USB Drive Section -->
+                            <!-- Row 9: General Build Options Checkboxes -->
                             <RowDefinition Height="Auto"/>
-                            <!-- Row 10: Post-Build Cleanup -->
+                            <!-- Row 10: Build USB Drive Section -->
+                            <RowDefinition Height="Auto"/>
+                            <!-- Row 11: Post-Build Cleanup -->
                             <RowDefinition Height="Auto"/>
                         </Grid.RowDefinitions>
                         <Grid.ColumnDefinitions>
@@ -729,11 +731,25 @@
                             <TextBlock Grid.Column="0" Text="Threads" VerticalAlignment="Center" ToolTip="Controls the number of parallel threads used by ForEach-Object -Parallel and sets the value of the -ThrottleLimit parameter. Default is 5. Used in Winget, Application Copy, and driver downloads"/>
                             <TextBox x:Name="txtThreads" Grid.Column="1" Margin="5" VerticalAlignment="Center" Width="50" HorizontalAlignment="Left" Text="5" ToolTip="Controls the number of parallel threads used by ForEach-Object -Parallel and sets the value of the -ThrottleLimit parameter. Default is 5. Used in Winget, Application Copy, and driver downloads"/>
                         </Grid>
-                        <!-- Row 7: General Build Options Header -->
+                        <!-- Row 7: BITS Priority -->
-                        <TextBlock Grid.Row="7" Text="General Build Options" FontWeight="Bold" FontSize="16" Margin="0,10,0,5"/>
+                        <Grid Grid.Row="7" Margin="0,5">
+                            <Grid.ColumnDefinitions>
+                                <ColumnDefinition Width="200"/>
+                                <ColumnDefinition Width="*"/>
+                            </Grid.ColumnDefinitions>
+                            <TextBlock Grid.Column="0" Text="BITS Priority" VerticalAlignment="Center" ToolTip="Controls the BITS download priority used by the UI and BuildFFUVM.ps1. Switch to Foreground to maximize download speed if needed."/>
+                            <ComboBox x:Name="cmbBitsPriority" Grid.Column="1" Margin="5" VerticalAlignment="Center" Width="150" HorizontalAlignment="Left" ToolTip="Controls the BITS download priority used by the UI and BuildFFUVM.ps1. Switch to Foreground to maximize download speed if needed.">
+                                <sys:String>Foreground</sys:String>
+                                <sys:String>High</sys:String>
+                                <sys:String>Normal</sys:String>
+                                <sys:String>Low</sys:String>
+                            </ComboBox>
+                        </Grid>
+                        <!-- Row 8: General Build Options Header -->
+                        <TextBlock Grid.Row="8" Text="General Build Options" FontWeight="Bold" FontSize="16" Margin="0,10,0,5"/>
 
-                        <!-- Row 8: General Build Options Checkboxes -->
+                        <!-- Row 9: General Build Options Checkboxes -->
-                        <WrapPanel Grid.Row="8" Margin="0,5">
+                        <WrapPanel Grid.Row="9" Margin="0,5">
                             <CheckBox x:Name="chkBuildUSBDriveEnable" Content="Build USB Drive" Margin="5" VerticalAlignment="Center" Tag="When set to $true, will partition and format a USB drive and copy the captured FFU to the drive."/>
                             <CheckBox x:Name="chkCompactOS" Content="Compact OS" Margin="5" VerticalAlignment="Center" Tag="When set to $true, will compact the OS when building the FFU."/>
                             <CheckBox x:Name="chkUpdateADK" Content="Update ADK" Margin="5" VerticalAlignment="Center" Tag="When set to $true, the script will check for and install/update to the latest Windows ADK and WinPE add-on."/>
@@ -745,8 +761,8 @@
                             <CheckBox x:Name="chkVerbose" Content="Verbose" Margin="5" VerticalAlignment="Center" Tag="When set to $true, will enable write-verbose output to the console for the build script."/>
                         </WrapPanel>
 
-                        <!-- Row 9: Build USB Drive Section -->
+                        <!-- Row 10: Build USB Drive Section -->
-                        <StackPanel Grid.Row="9" Margin="0,10,0,5" x:Name="usbDriveSection" Visibility="Collapsed">
+                        <StackPanel Grid.Row="10" Margin="0,10,0,5" x:Name="usbDriveSection" Visibility="Collapsed">
                             <TextBlock Text="Build USB Drive Settings" FontWeight="Bold" FontSize="16" Margin="0,0,0,10"/>
                             <StackPanel Margin="5,0,0,10">
                                 <CheckBox x:Name="chkAllowExternalHardDiskMedia" Content="Allow External Hard Disk Media" Margin="5" VerticalAlignment="Center" Tag="When set to $true, will allow the use of external hard disk media."/>
@@ -811,8 +827,8 @@
                             </StackPanel>
                         </StackPanel>
 
-                        <!-- Row 10: Post-Build Cleanup -->
+                        <!-- Row 11: Post-Build Cleanup -->
-                        <StackPanel Grid.Row="10" Margin="0,10,0,5">
+                        <StackPanel Grid.Row="11" Margin="0,10,0,5">
                             <TextBlock Text="Post-Build Cleanup" FontWeight="Bold" FontSize="16" Margin="0,0,0,5"/>
                             <CheckBox x:Name="chkCleanupAppsISO" Content="Cleanup Apps ISO" Margin="5" VerticalAlignment="Center" Tag="Remove Apps ISO after FFU capture."/>
                             <CheckBox x:Name="chkCleanupCaptureISO" Content="Cleanup Capture ISO" Margin="5" VerticalAlignment="Center" Tag="Remove WinPE capture ISO after FFU capture."/>

FFUDevelopment/FFU.Common/FFU.Common.Core.psm1

@@ -12,6 +12,10 @@ $script:CommonCoreLogFilePath = $null
 # Mutex for log file access
 $script:commonCoreLogMutexName = "Global\FFUCommonCoreLogMutex" # Unique name
 $script:commonCoreLogMutex = New-Object System.Threading.Mutex($false, $script:commonCoreLogMutexName)
+$script:BitsTransferPriority = 'Normal'
+if (-not [string]::IsNullOrWhiteSpace($env:FFU_BITS_PRIORITY)) {
+    $script:BitsTransferPriority = $env:FFU_BITS_PRIORITY
+}
 
 # Function to set the log file path for this module
 function Set-CommonCoreLogPath {
@@ -31,6 +35,23 @@ function Set-CommonCoreLogPath {
     }
 }
         
+function Set-BitsTransferPriority {
+    [CmdletBinding()]
+    param(
+        [Parameter(Mandatory = $true)]
+        [ValidateSet('Foreground', 'High', 'Normal', 'Low')]
+        [string]$Priority
+    )
+    $script:BitsTransferPriority = $Priority
+    try {
+        Set-Item -Path Env:FFU_BITS_PRIORITY -Value $Priority -ErrorAction Stop
+    }
+    catch {
+        WriteLog "Failed to set FFU_BITS_PRIORITY environment variable: $($_.Exception.Message)"
+    }
+    WriteLog "BITS transfer priority set to $Priority."
+}
+        
 # Centralized WriteLog function
 function WriteLog {
     [CmdletBinding()]
@@ -143,9 +164,23 @@ function Start-BitsTransferWithRetry {
         [string]$Source,
         [Parameter(Mandatory = $true)]
         [string]$Destination,
-        [int]$Retries = 3
+        [int]$Retries = 3,
+        [ValidateSet('Foreground','High','Normal','Low')]
+        [string]$Priority
     )
 
+    if ([string]::IsNullOrWhiteSpace($Priority)) {
+        if (-not [string]::IsNullOrWhiteSpace($env:FFU_BITS_PRIORITY)) {
+            $Priority = $env:FFU_BITS_PRIORITY
+        }
+        elseif (-not [string]::IsNullOrWhiteSpace($script:BitsTransferPriority)) {
+            $Priority = $script:BitsTransferPriority
+        }
+        else {
+            $Priority = 'Normal'
+        }
+    }
+
     $attempt = 0
     $lastError = $null
     $notLoggedOnHResult = [int]0x800704dd
@@ -158,7 +193,7 @@ function Start-BitsTransferWithRetry {
             $VerbosePreference = 'SilentlyContinue'
             $ProgressPreference = 'SilentlyContinue'
 
-            Start-BitsTransfer -Source $Source -Destination $Destination -Priority Normal -ErrorAction Stop
+            Start-BitsTransfer -Source $Source -Destination $Destination -Priority $Priority -ErrorAction Stop
             
             $ProgressPreference = $OriginalProgressPreference
             $VerbosePreference = $OriginalVerbosePreference
@@ -259,7 +294,7 @@ function ConvertTo-SafeName {
     # Collapse multiple consecutive dashes
     $sanitized = $sanitized -replace '-{2,}', '-'
     # Trim leading/trailing spaces, periods, and dashes
-    $sanitized = $sanitized.Trim(' ','.','-')
+    $sanitized = $sanitized.Trim(' ', '.', '-')
     if ([string]::IsNullOrWhiteSpace($sanitized)) {
         $sanitized = 'Unnamed'
     }

FFUDevelopment/FFUUI.Core/FFUUI.Core.Config.psm1

@@ -96,6 +96,7 @@ function Get-UIConfig {
         USBDriveList                   = @{}
         Username                       = $State.Controls.txtUsername.Text
         Threads                        = [int]$State.Controls.txtThreads.Text
+        BitsPriority                    = $State.Controls.cmbBitsPriority.SelectedItem
         MaxUSBDrives                   = [int]$State.Controls.txtMaxUSBDrives.Text
         Verbose                        = $State.Controls.chkVerbose.IsChecked
         VMHostIPAddress                = $State.Controls.txtVMHostIPAddress.Text
@@ -412,6 +413,7 @@ function Update-UIFromConfig {
     Set-UIValue -ControlName 'txtShareName' -PropertyName 'Text' -ConfigObject $ConfigContent -ConfigKey 'ShareName' -State $State
     Set-UIValue -ControlName 'txtUsername' -PropertyName 'Text' -ConfigObject $ConfigContent -ConfigKey 'Username' -State $State
     Set-UIValue -ControlName 'txtThreads' -PropertyName 'Text' -ConfigObject $ConfigContent -ConfigKey 'Threads' -State $State
+    Set-UIValue -ControlName 'cmbBitsPriority' -PropertyName 'SelectedItem' -ConfigObject $ConfigContent -ConfigKey 'BitsPriority' -State $State
     Set-UIValue -ControlName 'txtMaxUSBDrives' -PropertyName 'Text' -ConfigObject $ConfigContent -ConfigKey 'MaxUSBDrives' -State $State
     Set-UIValue -ControlName 'chkBuildUSBDriveEnable' -PropertyName 'IsChecked' -ConfigObject $ConfigContent -ConfigKey 'BuildUSBDrive' -State $State
     Set-UIValue -ControlName 'chkCompactOS' -PropertyName 'IsChecked' -ConfigObject $ConfigContent -ConfigKey 'CompactOS' -State $State
@@ -748,13 +750,14 @@ function Update-UIFromConfig {
             else {
                 $State.Controls.additionalFFUPanel.Visibility = 'Collapsed'
             }
-        }
+            }
-        catch {
+            catch {
-            WriteLog "LoadConfig: Error applying Additional FFU selections: $($_.Exception.Message)"
+                WriteLog "LoadConfig: Error applying Additional FFU selections: $($_.Exception.Message)"
-        }
+            }
         
-        WriteLog "LoadConfig: Configuration loading process finished."
+            Update-BitsPrioritySetting -State $State
-    }
+            WriteLog "LoadConfig: Configuration loading process finished."
+        }
 
 function Invoke-SaveConfiguration {
     param(

FFUDevelopment/FFUUI.Core/FFUUI.Core.Handlers.psm1

@@ -152,6 +152,17 @@ function Register-EventHandlers {
             $localState.Controls.chkPromptExternalHardDiskMedia.IsChecked = $false
         })
 
+    if ($null -ne $State.Controls.cmbBitsPriority) {
+        $State.Controls.cmbBitsPriority.Add_SelectionChanged({
+                param($eventSource, $selectionChangedEventArgs)
+                $window = [System.Windows.Window]::GetWindow($eventSource)
+                if ($null -eq $window -or $null -eq $window.Tag) {
+                    return
+                }
+                Update-BitsPrioritySetting -State $window.Tag
+            })
+    }
+
     # Additional FFU Files events
     $State.Controls.chkCopyAdditionalFFUFiles.Add_Checked({
             param($eventSource, $routedEventArgs)

FFUDevelopment/FFUUI.Core/FFUUI.Core.Initialize.psm1

@@ -118,6 +118,7 @@ function Initialize-UIControls {
     $State.Controls.txtShareName = $window.FindName('txtShareName')
     $State.Controls.txtUsername = $window.FindName('txtUsername')
     $State.Controls.txtThreads = $window.FindName('txtThreads')
+    $State.Controls.cmbBitsPriority = $window.FindName('cmbBitsPriority')
     $State.Controls.txtMaxUSBDrives = $window.FindName('txtMaxUSBDrives')
     $State.Controls.chkCompactOS = $window.FindName('chkCompactOS')
     $State.Controls.chkOptimize = $window.FindName('chkOptimize')
@@ -234,6 +235,7 @@ function Initialize-UIDefaults {
     $State.Controls.txtShareName.Text = $State.Defaults.generalDefaults.ShareName
     $State.Controls.txtUsername.Text = $State.Defaults.generalDefaults.Username
     $State.Controls.txtThreads.Text = $State.Defaults.generalDefaults.Threads
+    $State.Controls.cmbBitsPriority.SelectedItem = $State.Defaults.generalDefaults.BitsPriority
     $State.Controls.txtMaxUSBDrives.Text = $State.Defaults.generalDefaults.MaxUSBDrives
     $State.Controls.chkBuildUSBDriveEnable.IsChecked = $State.Defaults.generalDefaults.BuildUSBDriveEnable
     $State.Controls.chkCompactOS.IsChecked = $State.Defaults.generalDefaults.CompactOS
@@ -263,6 +265,7 @@ function Initialize-UIDefaults {
     $State.Controls.chkPromptExternalHardDiskMedia.IsEnabled = $State.Controls.chkAllowExternalHardDiskMedia.IsChecked
     $State.Controls.chkCopyAdditionalFFUFiles.IsChecked = $State.Defaults.generalDefaults.CopyAdditionalFFUFiles
     $State.Controls.additionalFFUPanel.Visibility = if ($State.Controls.chkCopyAdditionalFFUFiles.IsChecked) { 'Visible' } else { 'Collapsed' }
+    Update-BitsPrioritySetting -State $State
 
     # Hyper-V Settings defaults from General Defaults
     Initialize-VMSwitchData -State $State

FFUDevelopment/FFUUI.Core/FFUUI.Core.Shared.psm1

@@ -220,6 +220,32 @@ function Invoke-ProgressUpdate {
     $ProgressQueue.Enqueue(@{ Identifier = $Identifier; Status = $Status })
 }
 
+function Update-BitsPrioritySetting {
+    param(
+        [Parameter(Mandatory)]
+        [pscustomobject]$State
+    )
+
+    $combo = $State.Controls.cmbBitsPriority
+    if ($null -eq $combo) {
+        WriteLog "BITS priority control not available; skipping priority update."
+        return
+    }
+
+    $selectedPriority = $combo.SelectedItem
+    if ([string]::IsNullOrWhiteSpace($selectedPriority)) {
+        $selectedPriority = 'Normal'
+    }
+
+    try {
+        Set-BitsTransferPriority -Priority $selectedPriority
+        WriteLog "BITS transfer priority set to $selectedPriority."
+    }
+    catch {
+        WriteLog "Failed to set BITS transfer priority: $($_.Exception.Message)"
+    }
+}
+
 # Add a function to create a sortable list view
 function Add-SortableColumn {
     param(

FFUDevelopment/FFUUI.Core/FFUUI.Core.psm1

@@ -117,6 +117,7 @@ function Get-GeneralDefaults {
         ShareName                      = "FFUCaptureShare"
         Username                       = "ffu_user"
         Threads                        = 5
+        BitsPriority                   = 'Normal'
         MaxUSBDrives                   = 5
         BuildUSBDriveEnable            = $false
         CompactOS                      = $true