feat: add custom installation script.

README.md

@@ -15,6 +15,8 @@ Manage [Agent Skills](https://agentskills.io/specification) from the command lin
 ## Table of Contents
 
 - [Installation](#installation)
+  - [Shell (macOS / Linux)](#shell-macos--linux)
+  - [PowerShell (Windows)](#powershell-windows)
   - [Python](#python)
   - [Node](#node)
   - [Homebrew](#homebrew)
@@ -33,6 +35,33 @@ Manage [Agent Skills](https://agentskills.io/specification) from the command lin
 
 ## Installation
 
+### Shell (macOS / Linux)
+
+Download a prebuilt binary, verify its checksum, and install it to `~/.local/bin`. No Python, Node, or Homebrew required.
+
+```shell
+curl -fsSL --proto '=https' --tlsv1.2 https://raw.githubusercontent.com/xelandernt/skilly/main/install.sh | sh
+```
+
+Pin a version or change the install directory:
+
+```shell
+curl -fsSL --proto '=https' --tlsv1.2 https://raw.githubusercontent.com/xelandernt/skilly/main/install.sh | sh -s -- --version 0.0.32 --to /usr/local/bin
+```
+
+Run with `-s -- --help` to see all options (`--version`, `--to`, `--no-modify-path`, `--dry-run`, `--verbose`).
+
+### PowerShell (Windows)
+
+```powershell
+irm https://raw.githubusercontent.com/xelandernt/skilly/main/install.ps1 | iex
+```
+
+Pin a version:
+
+```powershell
+& ([scriptblock]::Create((irm https://raw.githubusercontent.com/xelandernt/skilly/main/install.ps1))) -Version 0.0.32
+```
 
 ### Python
 ```shell
@@ -55,6 +84,7 @@ brew install xelandernt/skilly/skilly
 
 | Method        | Ships                                                                                                |
 |---------------|------------------------------------------------------------------------------------------------------|
+| `install.sh` / `install.ps1` | Native Rust CLI from GitHub releases (macOS arm64/x64, Linux x64 glibc, Windows x64)   |
 | `uvx` / `pip` | Python package with import surface + CLI (pre-built wheels: Linux x64, macOS arm64/x64, Windows x64) |
 | `npx`         | Native Rust CLI (macOS arm64/x64, Linux x64 glibc, Windows x64)                                      |
 | `brew`        | Native Rust CLI (macOS arm64/x64, Linux x64)                                                         |

install.ps1

@@ -0,0 +1,176 @@
+<#
+.SYNOPSIS
+    skilly installer for Windows.
+
+.DESCRIPTION
+    Downloads the prebuilt skilly binary from GitHub releases, verifies its
+    SHA256 checksum, installs it, and adds the install directory to PATH.
+
+.EXAMPLE
+    irm https://raw.githubusercontent.com/xelandernt/skilly/main/install.ps1 | iex
+
+.EXAMPLE
+    & ([scriptblock]::Create((irm https://raw.githubusercontent.com/xelandernt/skilly/main/install.ps1))) -Version 0.0.32
+#>
+[CmdletBinding()]
+param(
+    [string]$Version = $env:SKILLY_VERSION,
+    [string]$InstallDir = $env:SKILLY_INSTALL_DIR,
+    [switch]$NoModifyPath,
+    [switch]$DryRun,
+    [switch]$Help
+)
+
+$ErrorActionPreference = 'Stop'
+Set-StrictMode -Version Latest
+
+$Repo = 'xelandernt/skilly'
+$Binary = 'skilly'
+
+function Write-Info { param([string]$Message) Write-Host $Message }
+function Write-Warn { param([string]$Message) Write-Warning $Message }
+
+function Show-Usage {
+    @"
+skilly installer (Windows)
+
+Usage:
+  irm https://raw.githubusercontent.com/$Repo/main/install.ps1 | iex
+
+  # With options:
+  & ([scriptblock]::Create((irm https://raw.githubusercontent.com/$Repo/main/install.ps1))) -Version 0.0.32
+
+Options:
+  -Version <version>   Version to install (default: latest, e.g. 0.0.32)
+  -InstallDir <dir>    Install directory (default: %LOCALAPPDATA%\skilly\bin)
+  -NoModifyPath        Do not add the install directory to your user PATH
+  -DryRun              Print what would happen without installing
+  -Help                Show this help
+
+Environment variables:
+  SKILLY_VERSION         Same as -Version
+  SKILLY_INSTALL_DIR     Same as -InstallDir
+  SKILLY_GITHUB_TOKEN    GitHub token for higher API rate limits (latest lookup)
+"@
+}
+
+if ($Help) {
+    Show-Usage
+    return
+}
+
+if ([string]::IsNullOrWhiteSpace($Version)) { $Version = 'latest' }
+if ([string]::IsNullOrWhiteSpace($InstallDir)) {
+    $InstallDir = Join-Path $env:LOCALAPPDATA 'skilly\bin'
+}
+
+function Get-Target {
+    $arch = $env:PROCESSOR_ARCHITECTURE
+    if ($env:PROCESSOR_ARCHITEW6432) { $arch = $env:PROCESSOR_ARCHITEW6432 }
+    switch ($arch) {
+        'AMD64' { return 'x86_64-pc-windows-msvc' }
+        default {
+            throw "no prebuilt skilly binary for architecture '$arch'. Supported: x86_64 (AMD64). Install via 'uvx skilly', 'npx @xelandernt/skilly', or 'cargo install' instead."
+        }
+    }
+}
+
+function Get-AuthHeaders {
+    $token = $env:SKILLY_GITHUB_TOKEN
+    if ([string]::IsNullOrWhiteSpace($token)) { return @{} }
+    return @{ Authorization = "Bearer $token" }
+}
+
+function Resolve-Version {
+    param([string]$Requested)
+    if ($Requested -ne 'latest') { return $Requested }
+    $api = "https://api.github.com/repos/$Repo/releases/latest"
+    $headers = Get-AuthHeaders
+    $headers['Accept'] = 'application/vnd.github+json'
+    try {
+        $release = Invoke-RestMethod -Uri $api -Headers $headers -UseBasicParsing
+    }
+    catch {
+        throw "failed to query latest release: $($_.Exception.Message)"
+    }
+    if ([string]::IsNullOrWhiteSpace($release.tag_name)) {
+        throw 'could not determine latest version from GitHub API'
+    }
+    return $release.tag_name
+}
+
+function Test-Checksum {
+    param([string]$ArchivePath, [string]$ChecksumsPath, [string]$Name)
+    $line = Select-String -Path $ChecksumsPath -Pattern ([regex]::Escape($Name)) | Select-Object -First 1
+    if (-not $line) { throw "no checksum found for $Name" }
+    $expected = ($line.Line -split '\s+')[0].ToLower()
+    $actual = (Get-FileHash -Path $ArchivePath -Algorithm SHA256).Hash.ToLower()
+    if ($expected -ne $actual) {
+        throw "checksum mismatch for ${Name}: expected $expected, got $actual"
+    }
+}
+
+function Add-ToUserPath {
+    param([string]$Dir)
+    if ($NoModifyPath) { return }
+    $userPath = [Environment]::GetEnvironmentVariable('Path', 'User')
+    if ($null -eq $userPath) { $userPath = '' }
+    $entries = $userPath -split ';' | Where-Object { $_ -ne '' }
+    if ($entries -contains $Dir) { return }
+    $newPath = if ([string]::IsNullOrEmpty($userPath)) { $Dir } else { "$userPath;$Dir" }
+    [Environment]::SetEnvironmentVariable('Path', $newPath, 'User')
+    $env:Path = "$env:Path;$Dir"
+    Write-Info "Added $Dir to your user PATH. Restart your terminal to pick it up."
+}
+
+$target = Get-Target
+$Version = Resolve-Version -Requested $Version
+
+$base = "https://github.com/$Repo/releases/download/$Version"
+$archiveName = "$Binary-$Version-$target.zip"
+$archiveUrl = "$base/$archiveName"
+$checksumsUrl = "$base/$Binary-sha256sums.txt"
+$binaryName = "$Binary.exe"
+
+Write-Info "Installing $Binary $Version ($target) to $InstallDir"
+
+if ($DryRun) {
+    Write-Info "[dry-run] would download: $archiveUrl"
+    Write-Info "[dry-run] would verify against: $checksumsUrl"
+    Write-Info "[dry-run] would install to: $(Join-Path $InstallDir $binaryName)"
+    return
+}
+
+$tmp = Join-Path ([System.IO.Path]::GetTempPath()) "skilly-install-$(Get-Random)"
+New-Item -ItemType Directory -Path $tmp -Force | Out-Null
+try {
+    $archivePath = Join-Path $tmp $archiveName
+    $checksumsPath = Join-Path $tmp "$Binary-sha256sums.txt"
+
+    try {
+        Invoke-WebRequest -Uri $archiveUrl -OutFile $archivePath -UseBasicParsing
+    }
+    catch {
+        throw "failed to download ${archiveUrl} (does version $Version exist?): $($_.Exception.Message)"
+    }
+    Invoke-WebRequest -Uri $checksumsUrl -OutFile $checksumsPath -UseBasicParsing
+
+    Test-Checksum -ArchivePath $archivePath -ChecksumsPath $checksumsPath -Name $archiveName
+
+    $extractDir = Join-Path $tmp 'extract'
+    Expand-Archive -Path $archivePath -DestinationPath $extractDir -Force
+    $extracted = Join-Path $extractDir $binaryName
+    if (-not (Test-Path $extracted)) {
+        throw "archive did not contain $binaryName"
+    }
+
+    New-Item -ItemType Directory -Path $InstallDir -Force | Out-Null
+    Copy-Item -Path $extracted -Destination (Join-Path $InstallDir $binaryName) -Force
+
+    Write-Info "Installed $Binary to $(Join-Path $InstallDir $binaryName)"
+    Add-ToUserPath -Dir $InstallDir
+    Write-Info "Run '$Binary --help' to get started."
+}
+finally {
+    if (Test-Path $tmp) { Remove-Item -Path $tmp -Recurse -Force -ErrorAction SilentlyContinue }
+}