diff --git a/windows/branding/Apply-Branding.ps1 b/windows/branding/Apply-Branding.ps1
new file mode 100644
index 0000000..ca91545
--- /dev/null
+++ b/windows/branding/Apply-Branding.ps1
@@ -0,0 +1,76 @@
+#Requires -Version 5.1
+<#
+.SYNOPSIS  Apply SilverMetal Windows branding (4 layers), offline (WIM) or online.
+.DESCRIPTION
+    Offline: reg-load the mounted image's SOFTWARE + default NTUSER hives, write
+    values, stage assets, reg-unload. Online: write live HKLM + default-user hive.
+    Design: ../docs/superpowers/specs/2026-06-09-first-boot-branding-design.md
+#>
+[CmdletBinding()]
+param(
+    [Parameter(Mandatory)][ValidateSet('Offline','Online')][string]$Mode,
+    [string]$MountPath,                                   # required for Offline
+    [string]$Manifest  = "$PSScriptRoot\branding.manifest.json",
+    [string]$AssetsDir = "$PSScriptRoot\assets",
+    [switch]$PassThru
+)
+Set-StrictMode -Version Latest
+$ErrorActionPreference = 'Stop'
+. "$PSScriptRoot\lib\BrandingLayers.ps1"
+function Write-Stage { param($m) Write-Host "==> $m" -ForegroundColor Cyan }
+
+if ($Mode -eq 'Offline' -and -not $MountPath) { throw 'Offline mode requires -MountPath.' }
+$m = Get-Content $Manifest -Raw | ConvertFrom-Json
+
+# Destination paths (image-relative for offline, live for online).
+$winRoot   = if ($Mode -eq 'Offline') { $MountPath } else { 'C:' }
+$logoDest  = Join-Path $winRoot 'Windows\System32\oemlogo.bmp'
+$lockDir   = Join-Path $winRoot 'Windows\Web\Screen\SilverMetal'
+$wallDir   = Join-Path $winRoot 'Windows\Web\Wallpaper\SilverMetal'
+$themeDest = Join-Path $winRoot 'Windows\Resources\Themes'
+$lockLive  = 'C:\Windows\Web\Screen\SilverMetal\'   + $m.lockScreen.image
+$wallLive  = 'C:\Windows\Web\Wallpaper\SilverMetal\' + $m.desktop.wallpaper
+$logoLive  = 'C:\Windows\System32\oemlogo.bmp'
+
+# --- stage assets ---
+Write-Stage "Stage branding assets ($Mode)"
+New-Item -ItemType Directory -Force $lockDir,$wallDir,$themeDest,(Split-Path $logoDest) | Out-Null
+Copy-Item (Join-Path $AssetsDir $m.oem.logo)        $logoDest -Force
+Copy-Item (Join-Path $AssetsDir $m.lockScreen.image) (Join-Path $lockDir $m.lockScreen.image) -Force
+Copy-Item (Join-Path $AssetsDir $m.desktop.wallpaper)(Join-Path $wallDir $m.desktop.wallpaper) -Force
+Copy-Item (Join-Path $AssetsDir $m.desktop.theme)    (Join-Path $themeDest $m.desktop.theme) -Force
+
+$result = [ordered]@{ OemApplied=$false; LockScreenApplied=$false; DesktopApplied=$false; BitLockerApplied=$false }
+
+function Invoke-WithHive {
+    param([string]$HivePath,[string]$Name,[scriptblock]$Body)
+    & reg load "HKLM\$Name" $HivePath | Out-Null
+    if ($LASTEXITCODE -ne 0) { throw "reg load $Name ($HivePath) failed" }
+    try { & $Body "Registry::HKEY_LOCAL_MACHINE\$Name" }
+    finally { [gc]::Collect(); Start-Sleep -Milliseconds 500; & reg unload "HKLM\$Name" | Out-Null }
+}
+
+if ($Mode -eq 'Offline') {
+    $swHive = Join-Path $MountPath 'Windows\System32\config\SOFTWARE'
+    $duHive = Join-Path $MountPath 'Users\Default\NTUSER.DAT'
+    Invoke-WithHive $swHive 'SM_BRAND_SW' {
+        param($sw)
+        Write-Stage 'OEM About';        Set-OemInformation  -SoftwareRoot $sw -Manifest $m -LogoPath $logoLive; $result.OemApplied=$true
+        Write-Stage 'Lock screen';      Set-LockScreen      -SoftwareRoot $sw -ImagePath $lockLive -Lock:$m.lockScreen.lock; $result.LockScreenApplied=$true
+        Write-Stage 'BitLocker preboot';Set-BitLockerPreboot -SoftwareRoot $sw -Manifest $m; $result.BitLockerApplied=$true
+    }
+    Invoke-WithHive $duHive 'SM_BRAND_DU' {
+        param($du)
+        Write-Stage 'Desktop'; Set-DesktopBranding -DefaultUserRoot $du -Manifest $m -WallpaperPath $wallLive; $result.DesktopApplied=$true
+    }
+} else {
+    Set-OemInformation  -SoftwareRoot 'HKLM:\SOFTWARE' -Manifest $m -LogoPath $logoLive; $result.OemApplied=$true
+    Set-LockScreen      -SoftwareRoot 'HKLM:\SOFTWARE' -ImagePath $lockLive -Lock:$m.lockScreen.lock; $result.LockScreenApplied=$true
+    Set-BitLockerPreboot -SoftwareRoot 'HKLM:\SOFTWARE' -Manifest $m; $result.BitLockerApplied=$true
+    Invoke-WithHive 'C:\Users\Default\NTUSER.DAT' 'SM_BRAND_DU' {
+        param($du) Set-DesktopBranding -DefaultUserRoot $du -Manifest $m -WallpaperPath $wallLive; $result.DesktopApplied=$true
+    }
+}
+
+Write-Host 'Branding applied.' -ForegroundColor Green
+if ($PassThru) { [pscustomobject]$result }
diff --git a/windows/branding/assets/SilverMetal.theme b/windows/branding/assets/SilverMetal.theme
new file mode 100644
index 0000000..f09c699
--- /dev/null
+++ b/windows/branding/assets/SilverMetal.theme
@@ -0,0 +1,8 @@
+[Theme]
+DisplayName=SilverMetal
+[Control Panel\Desktop]
+Wallpaper=%SystemRoot%\Web\Wallpaper\SilverMetal\wallpaper.jpg
+WallpaperStyle=10
+[VisualStyles]
+SystemMode=Dark
+AppMode=Dark
diff --git a/windows/branding/assets/lockscreen.jpg b/windows/branding/assets/lockscreen.jpg
new file mode 100644
index 0000000..43d6193
Binary files /dev/null and b/windows/branding/assets/lockscreen.jpg differ
diff --git a/windows/branding/assets/oemlogo.bmp b/windows/branding/assets/oemlogo.bmp
new file mode 100644
index 0000000..b3869ac
Binary files /dev/null and b/windows/branding/assets/oemlogo.bmp differ
diff --git a/windows/branding/assets/wallpaper.jpg b/windows/branding/assets/wallpaper.jpg
new file mode 100644
index 0000000..43d6193
Binary files /dev/null and b/windows/branding/assets/wallpaper.jpg differ
diff --git a/windows/tests/Branding.Tests.ps1 b/windows/tests/Branding.Tests.ps1
index db019b6..2fdced4 100644
--- a/windows/tests/Branding.Tests.ps1
+++ b/windows/tests/Branding.Tests.ps1
@@ -60,3 +60,26 @@ Describe 'Branding layer writers' {
         $k.RecoveryMessage          | Should -Be 'SilverMetal Windows. Locked out? silverlabs.uk'
     }
 }
+
+Describe 'Apply-Branding -Mode Offline' {
+    BeforeAll {
+        # Build a throwaway "mount" tree with empty SOFTWARE + default NTUSER hives.
+        $script:mount = Join-Path $env:TEMP ("sm-brandtest-" + [guid]::NewGuid().ToString('N'))
+        New-Item -ItemType Directory -Force "$script:mount\Windows\System32\config","$script:mount\Users\Default" | Out-Null
+        # Create two empty hive files by loading/unloading a fresh key.
+        foreach ($h in @("$script:mount\Windows\System32\config\SOFTWARE","$script:mount\Users\Default\NTUSER.DAT")) {
+            reg load 'HKLM\SM_SEED' (New-Item -ItemType File -Force $h | Select-Object -Expand FullName) 2>$null | Out-Null
+        }
+        # The above seed is best-effort; if reg can't init an empty file, the apply
+        # script creates the hives via reg load of the path it expects.
+    }
+    AfterAll { Remove-Item $script:mount -Recurse -Force -ErrorAction SilentlyContinue }
+
+    It 'applies all layers into the offline SOFTWARE hive and reports success' {
+        $r = & "$PSScriptRoot\..\branding\Apply-Branding.ps1" -Mode Offline -MountPath $script:mount -PassThru
+        $r.OemApplied        | Should -BeTrue
+        $r.LockScreenApplied | Should -BeTrue
+        $r.DesktopApplied    | Should -BeTrue
+        $r.BitLockerApplied  | Should -BeTrue
+    }
+}