diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..99547e2
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,4 @@
+* text=auto
+*.sh text eol=lf
+*.yml text eol=lf
+*.yaml text eol=lf
diff --git a/.github/workflows/validate.yml b/.github/workflows/validate.yml
index 75dbec9..fd9d21d 100644
--- a/.github/workflows/validate.yml
+++ b/.github/workflows/validate.yml
@@ -43,6 +43,11 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v7
 
+      - name: Set up Python
+        uses: actions/setup-python@v7
+        with:
+          python-version: "3.11"
+
       - name: Test install and uninstall
         shell: powershell
         run: .\scripts\test-installers.ps1
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 93b6774..9e1c4f6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,8 @@
 - Added `CAVEMAN_OPENCODE_DEFAULT_LEVEL` install-time override for `lite`, `full`, `ultra`, `wenyan`, `wenyan-lite`, and `wenyan-ultra`.
 - Accepted trailing commas in existing OpenCode configuration without changing comma-like text inside JSON strings.
 - Added functional install/uninstall tests for POSIX and Windows PowerShell environments.
+- Replaced the Windows `Expand-Archive` dependency with .NET ZIP extraction for hosts where `Microsoft.PowerShell.Archive` cannot load.
+- Enforced LF endings for shell scripts and workflow files across Windows and POSIX checkouts.
 
 ## 0.2.0
 
diff --git a/install-opencode.ps1 b/install-opencode.ps1
index f63c5b0..1d32e42 100644
--- a/install-opencode.ps1
+++ b/install-opencode.ps1
@@ -92,6 +92,11 @@ function ConvertFrom-OpenCodeJson([string]$Content) {
   }
 }
 
+function Expand-ZipArchive([string]$Path, [string]$DestinationPath) {
+  Add-Type -AssemblyName System.IO.Compression.FileSystem -ErrorAction Stop
+  [System.IO.Compression.ZipFile]::ExtractToDirectory($Path, $DestinationPath)
+}
+
 if (-not (Test-Path -LiteralPath (Join-Path $sourceOpenCode "AGENTS.md"))) {
   $archiveUrl = $env:CAVEMAN_OPENCODE_ARCHIVE_URL
   if ([string]::IsNullOrWhiteSpace($archiveUrl)) {
@@ -103,8 +108,8 @@ if (-not (Test-Path -LiteralPath (Join-Path $sourceOpenCode "AGENTS.md"))) {
   New-Item -ItemType Directory -Force $tempDir | Out-Null
 
   Write-Host "Downloading Caveman for OpenCode from $archiveUrl"
-  Invoke-WebRequest -Uri $archiveUrl -OutFile $zipPath
-  Expand-Archive -LiteralPath $zipPath -DestinationPath $tempDir -Force
+  Invoke-WebRequest -UseBasicParsing -Uri $archiveUrl -OutFile $zipPath
+  Expand-ZipArchive -Path $zipPath -DestinationPath $tempDir
 
   $sourceDir = Get-ChildItem -LiteralPath $tempDir -Directory | Select-Object -First 1
   if (-not $sourceDir) {
diff --git a/scripts/test-installers.ps1 b/scripts/test-installers.ps1
index d4786a0..ac50303 100644
--- a/scripts/test-installers.ps1
+++ b/scripts/test-installers.ps1
@@ -10,9 +10,10 @@ $repo = Split-Path -Parent $PSScriptRoot
 $testRoot = Join-Path ([System.IO.Path]::GetTempPath()) ("caveman-opencode-test-" + [guid]::NewGuid().ToString("N"))
 $originalUserProfile = $env:USERPROFILE
 $originalDefaultLevel = $env:CAVEMAN_OPENCODE_DEFAULT_LEVEL
+$originalArchiveUrl = $env:CAVEMAN_OPENCODE_ARCHIVE_URL
+$serverProcess = $null
 
 try {
-  $env:USERPROFILE = $testRoot
   $env:CAVEMAN_OPENCODE_DEFAULT_LEVEL = "ultra"
 
   $configDir = Join-Path $testRoot ".config\opencode"
@@ -37,7 +38,57 @@ try {
 }
 '@ | Set-Content -LiteralPath $configFile -Encoding UTF8
 
-  & (Join-Path $repo "install-opencode.ps1")
+  Add-Type -AssemblyName System.IO.Compression.FileSystem -ErrorAction Stop
+  $archiveRoot = Join-Path $testRoot "archive"
+  $archiveSource = Join-Path $archiveRoot "caveman-opencode-main"
+  $archivePath = Join-Path $testRoot "source.zip"
+  New-Item -ItemType Directory -Force -Path $archiveSource | Out-Null
+  Copy-Item -Recurse -Force -LiteralPath (Join-Path $repo ".opencode") -Destination $archiveSource
+  [System.IO.Compression.ZipFile]::CreateFromDirectory($archiveRoot, $archivePath)
+
+  $portProbe = [System.Net.Sockets.TcpListener]::new([System.Net.IPAddress]::Loopback, 0)
+  $portProbe.Start()
+  $port = ([System.Net.IPEndPoint]$portProbe.LocalEndpoint).Port
+  $portProbe.Stop()
+  $serverUrl = "http://127.0.0.1:$port/source.zip"
+  $serverOutputPath = Join-Path $testRoot "archive-server.out"
+  $serverErrorPath = Join-Path $testRoot "archive-server.err"
+  $python = (Get-Command python -ErrorAction Stop).Source
+  $pythonArguments = "-m http.server $port --bind 127.0.0.1 --directory `"$testRoot`""
+  $serverProcess = Start-Process -FilePath $python -ArgumentList $pythonArguments -PassThru -WindowStyle Hidden -RedirectStandardOutput $serverOutputPath -RedirectStandardError $serverErrorPath
+
+  $remoteDir = Join-Path $testRoot "remote-installer"
+  $remoteInstaller = Join-Path $remoteDir "install-opencode.ps1"
+  New-Item -ItemType Directory -Force -Path $remoteDir | Out-Null
+  Copy-Item -Force -LiteralPath (Join-Path $repo "install-opencode.ps1") -Destination $remoteInstaller
+  $env:CAVEMAN_OPENCODE_ARCHIVE_URL = $serverUrl
+
+  $serverDeadline = [DateTime]::UtcNow.AddSeconds(10)
+  $serverReady = $false
+  while (-not $serverReady -and [DateTime]::UtcNow -lt $serverDeadline) {
+    if ($serverProcess.HasExited) {
+      $serverDetails = Get-Content -LiteralPath $serverErrorPath -Raw -ErrorAction SilentlyContinue
+      throw "Archive server exited before startup. $serverDetails"
+    }
+    $client = [System.Net.Sockets.TcpClient]::new()
+    try {
+      $client.Connect("127.0.0.1", $port)
+      $serverReady = $client.Connected
+    } catch {
+      Start-Sleep -Milliseconds 100
+    } finally {
+      $client.Close()
+    }
+  }
+  Assert-True $serverReady "archive server should start"
+
+  $env:USERPROFILE = $testRoot
+  try {
+    & $remoteInstaller
+  } catch {
+    $serverDetails = Get-Content -LiteralPath $serverErrorPath -Raw -ErrorAction SilentlyContinue
+    throw "Remote installer failed: $($_.Exception.Message). Archive server: $serverDetails"
+  }
 
   $config = Get-Content -LiteralPath $configFile -Raw -Encoding UTF8 | ConvertFrom-Json
   $skills = @("caveman", "caveman-commit", "caveman-review", "caveman-help", "caveman-compress")
@@ -74,6 +125,15 @@ try {
   } else {
     $env:CAVEMAN_OPENCODE_DEFAULT_LEVEL = $originalDefaultLevel
   }
+  if ($null -eq $originalArchiveUrl) {
+    Remove-Item Env:CAVEMAN_OPENCODE_ARCHIVE_URL -ErrorAction SilentlyContinue
+  } else {
+    $env:CAVEMAN_OPENCODE_ARCHIVE_URL = $originalArchiveUrl
+  }
+  if ($null -ne $serverProcess -and -not $serverProcess.HasExited) {
+    Stop-Process -Id $serverProcess.Id -Force -ErrorAction SilentlyContinue
+    [void]$serverProcess.WaitForExit(5000)
+  }
   if (Test-Path -LiteralPath $testRoot) {
     Remove-Item -Recurse -Force -LiteralPath $testRoot
   }