OpenCode installation on Windows without local administrator rights

Invoke-OpenCodeInstall.ps1

<#
.SYNOPSIS
Bootstraps a fully user-scoped (non-admin) Node.js + npm environment and installs OpenCode.

.DESCRIPTION
This script downloads the latest Node.js LTS Windows x64 ZIP and extracts it into a 
shortened version-based directory (e.g., node_v24) under the user's LOCALAPPDATA.

It then:
- Configures user-level PATH to include Node.js and npm global binaries
- Redirects npm global installs to a user-writable AppData path
- Installs the OpenCode CLI globally via npm (without requiring admin rights)
- Leaves the system in a clean, portable, non-admin configuration

KEY POINTS
- No administrator privileges required at any step
- Uses ZIP distribution instead of MSI to avoid Program Files
- Keeps Node install path short and version-based (e.g., node_v24)
- Ensures npm global installs are isolated to user profile

POST-SETUP
User must restart their terminal session for PATH updates to take effect.
#>

# --- CONFIG ---
$baseDir = "$env:LOCALAPPDATA\nodejs"
$tmpZip  = "$env:TEMP\node-lts.zip"
$nodeApi = "https://nodejs.org/dist/index.json"

Write-Output '==> Getting latest Node.js LTS version...'

# Fetch Node release list and pick latest LTS
$nodeIndex = Invoke-RestMethod $nodeApi
$ltsVersion = ($nodeIndex | Where-Object { $_.lts -ne $false } | Select-Object -First 1).version

# Normalize names
$versionClean = $ltsVersion.TrimStart("v")
$majorVersion = $versionClean.Split(".")[0]
$shortFolder  = "node_v$majorVersion"
$installDir   = Join-Path $baseDir $shortFolder

# Build download URL
$zipName = "node-$ltsVersion-win-x64.zip"
$downloadUrl = "https://nodejs.org/dist/$ltsVersion/$zipName"

Write-Output "==> Latest LTS: $ltsVersion"
Write-Output "==> Downloading: $downloadUrl"

# Prepare dirs
New-Item -ItemType Directory -Force -Path $baseDir | Out-Null

# Download ZIP
Invoke-WebRequest -Uri $downloadUrl -OutFile $tmpZip
Unblock-File $tmpZip

Write-Output '==> Extracting...'

# Extract
Expand-Archive $tmpZip -DestinationPath $baseDir -Force

# Rename extracted folder to short name
$extractedPath = Join-Path $baseDir ("node-$ltsVersion-win-x64")
if (Test-Path $installDir) {
    Remove-Item -Recurse -Force $installDir
}
Rename-Item -Path $extractedPath -NewName $shortFolder

# Cleanup zip
Remove-Item $tmpZip -Force

Write-Output '==> Setting user PATH...'

# Add Node + npm global bin to PATH
$npmDir = "$env:LOCALAPPDATA\npm"
$newPath = "$installDir;$npmDir;$env:PATH"
setx PATH $newPath | Out-Null

Write-Output '==> Configuring npm prefix...'

# Use full path to npm (since PATH not active yet)
$npmExe = Join-Path $installDir "npm.cmd"
& $npmExe config set prefix $npmDir

Write-Output '==> Installing OpenCode...'

& $npmExe install -g opencode-ai

Write-Output ''
Write-Output '✅ DONE'
Write-Output ''
Write-Output 'IMPORTANT: Restart your terminal before using opencode.'
Write-Output ''
Write-Output 'After terminal restart, test with:'
Write-Output '  node -v'
Write-Output '  npm -v'
Write-Output '  opencode --version'
Write-Output ''