diff --git a/scripts/install.ps1 b/scripts/install.ps1
index 30b558f..b0a107f 100644
--- a/scripts/install.ps1
+++ b/scripts/install.ps1
@@ -1,24 +1,38 @@
 [CmdletBinding()]
-param([switch]$DryRun)
+param(
+    [switch]$DryRun,
+    [ValidateSet('Codex','Claude','Both')][string]$Client,
+    [ValidateSet('Windows','Linux')][string]$Platform,
+    [switch]$UpdatePlugins
+)
 $ErrorActionPreference = 'Stop'
 $root = Split-Path $PSScriptRoot -Parent
 . (Join-Path $PSScriptRoot 'lib/plugins.ps1')
+. (Join-Path $PSScriptRoot 'lib/manifest.ps1')
 $buildScript = Join-Path $PSScriptRoot 'build.ps1'
 & $buildScript
 if (-not $?) { throw 'Build failed. Installation was not started.' }
 $generated = Join-Path $root 'generated'
 if (-not (Test-Path $generated)) { throw 'Generated output is missing after a successful build.' }
-Write-Output 'Select target platform:'
-Write-Output '1) Windows'
-Write-Output '2) Linux'
-do { $platformSelection = Read-Host 'Selection [1-2]' } while ($platformSelection -notin @('1','2'))
-$platform = @{'1'='windows'; '2'='linux'}[$platformSelection]
-Write-Output 'Select installation target:'
-Write-Output '1) Codex'
-Write-Output '2) Claude'
-Write-Output '3) Both'
-do { $selection = Read-Host 'Selection [1-3]' } while ($selection -notin @('1','2','3'))
-$Client = @{'1'='Codex'; '2'='Claude'; '3'='Both'}[$selection]
+
+if (-not $Platform) {
+    Write-Output 'Select target platform:'
+    Write-Output '1) Windows'
+    Write-Output '2) Linux'
+    do { $platformSelection = Read-Host 'Selection [1-2]' } while ($platformSelection -notin @('1','2'))
+    $Platform = @{'1'='Windows'; '2'='Linux'}[$platformSelection]
+}
+$platform = $Platform.ToLowerInvariant()
+
+if (-not $Client) {
+    Write-Output 'Select installation target:'
+    Write-Output '1) Codex'
+    Write-Output '2) Claude'
+    Write-Output '3) Both'
+    do { $selection = Read-Host 'Selection [1-3]' } while ($selection -notin @('1','2','3'))
+    $Client = @{'1'='Codex'; '2'='Claude'; '3'='Both'}[$selection]
+}
+
 $stamp = Get-Date -Format 'yyyyMMdd-HHmmss'
 $homePath = [Environment]::GetFolderPath('UserProfile')
 $shellCommand = 'pwsh -NoProfile -ExecutionPolicy Bypass -File'
@@ -28,31 +42,11 @@ $targets = @()
 if ($Client -in @('Codex','Both')) { $targets += @{ Source=(Join-Path $generated "codex-$platform"); Destination=(Join-Path $homePath '.codex') } }
 if ($Client -in @('Codex','Both')) { $targets += @{ Source=(Join-Path $generated "codex-$platform/skills"); Destination=(Join-Path $homePath '.agents/skills') } }
 if ($Client -in @('Claude','Both')) { $targets += @{ Source=(Join-Path $generated "claude-$platform"); Destination=(Join-Path $homePath '.claude') } }
+
 foreach ($item in $targets) {
-    $backupRoot = Join-Path $item.Destination 'backups'
-    Get-ChildItem $item.Source -File -Recurse | ForEach-Object {
-        $relative = $_.FullName.Substring($item.Source.Length).TrimStart([char[]]@('\','/'))
-        $target = Join-Path $item.Destination $relative
-        if ($DryRun) { Write-Output "DRYRUN $($_.FullName) -> $target"; return }
-        if (Test-Path $target) {
-            $backup = Join-Path $backupRoot $relative
-            New-Item (Split-Path $backup -Parent) -ItemType Directory -Force | Out-Null
-            Copy-Item $target "$backup.$stamp" -Force
-        }
-        New-Item (Split-Path $target -Parent) -ItemType Directory -Force | Out-Null
-        $content = Get-Content $_.FullName -Raw
-        if ($content.Contains('__AI_CONFIG_ROOT__') -or $content.Contains('__HOOK_COMMAND__') -or $content.Contains('__WINDOWS_HOOK_COMMAND__')) {
-            $replacement = $item.Destination.Replace('\','/')
-            $content = $content.Replace('__AI_CONFIG_ROOT__', $replacement)
-            $content = $content.Replace('__HOOK_COMMAND__', $shellCommand)
-            $content = $content.Replace('__WINDOWS_HOOK_COMMAND__', $windowsShellCommand)
-            $content = $content.Replace('__HOOK_SCRIPT__', 'flashbang.ps1')
-            $content = $content.Replace('__WINDOWS_HOOK_SCRIPT__', 'flashbang.ps1')
-            [System.IO.File]::WriteAllText($target, $content, (New-Object System.Text.UTF8Encoding($false)))
-        }
-        else { Copy-Item $_.FullName $target -Force }
-        Write-Output "INSTALL $target"
-    }
+    Sync-ManagedDestination -Source $item.Source -Destination $item.Destination -Stamp $stamp `
+        -AiConfigRoot $item.Destination.Replace('\','/') -ShellCommand $shellCommand -WindowsShellCommand $windowsShellCommand -DryRun:$DryRun
 }
-Install-ConfiguredPlugins -RepositoryRoot $root -Client $Client -DryRun:$DryRun -Update
+
+Install-ConfiguredPlugins -RepositoryRoot $root -Client $Client -DryRun:$DryRun -Update:$UpdatePlugins
 Write-Output ($(if ($DryRun) { 'PASS install dry-run' } else { 'PASS install' }))