[CmdletBinding()]
param(
  [string]$BackendCache = "",
  [switch]$AllowDownload
)
$ErrorActionPreference = "Stop"
$Root = Resolve-Path (Join-Path $PSScriptRoot "..\..")
$ollamaDest = Join-Path $Root "backends\ollama\windows\ollama.exe"
$llamaDest = Join-Path $Root "backends\llama.cpp\windows\llama-server.exe"
New-Item -ItemType Directory -Force -Path (Split-Path $ollamaDest),(Split-Path $llamaDest) | Out-Null

if ($BackendCache) {
  if (Test-Path "$BackendCache\ollama.exe") { Copy-Item "$BackendCache\ollama.exe" $ollamaDest -Force }
  if (Test-Path "$BackendCache\llama-server.exe") { Copy-Item "$BackendCache\llama-server.exe" $llamaDest -Force }
}

if (!(Test-Path $ollamaDest)) { Write-Warning "Missing ollama.exe. Put it in $ollamaDest or pass -BackendCache." }
if (!(Test-Path $llamaDest)) { Write-Warning "Missing llama-server.exe. Put it in $llamaDest or pass -BackendCache." }

# Production rule: pin backend versions and verify checksums in manifest/backend-sources.json.