Add Windows support via PowerShell scripts

This adds native Windows support to the superpowers plugin by creating PowerShell equivalents of the bash scripts.

Changes:
- Add hooks/session-start.ps1 for Windows SessionStart hook
- Add lib/initialize-skills.ps1 for Windows skills initialization
- Update hooks/hooks.json to detect platform and use appropriate script
  - Windows (win32): uses PowerShell scripts
  - macOS/Linux (darwin/linux): uses existing bash scripts

The PowerShell scripts provide the same functionality as the bash versions:
- Load and inject skills context on session start
- Clone and update the superpowers-skills repository
- Handle legacy installation migration
- Offer GitHub fork option when gh CLI is available

Tested on Windows 10/11 with successful JSON output generation.

Author: simnJS

hooks/hooks.json

@@ -6,7 +6,13 @@
         "hooks": [
           {
             "type": "command",
-            "command": "${CLAUDE_PLUGIN_ROOT}/hooks/session-start.sh"
+            "command": "powershell -ExecutionPolicy Bypass -File \"${CLAUDE_PLUGIN_ROOT}/hooks/session-start.ps1\"",
+            "platforms": ["win32"]
+          },
+          {
+            "type": "command",
+            "command": "${CLAUDE_PLUGIN_ROOT}/hooks/session-start.sh",
+            "platforms": ["darwin", "linux"]
           }
         ]
       }

hooks/session-start.ps1

@@ -0,0 +1,51 @@
+# SessionStart hook for superpowers plugin (Windows PowerShell version)
+
+# Determine plugin root directory
+$scriptDir = Split-Path -Parent $MyInvocation.MyCommand.Path
+$pluginRoot = Split-Path -Parent $scriptDir
+
+# Check if legacy skills directory exists and build warning
+$warningMessage = ""
+$legacySkillsDir = Join-Path $env:USERPROFILE ".config\superpowers\skills"
+if (Test-Path $legacySkillsDir) {
+    $warningMessage = "`n`n⚠️ **WARNING:** Superpowers now uses Claude Code's skills system. Custom skills in ~/.config/superpowers/skills will not be read."
+}
+
+# Read using-superpowers content
+$skillFile = Join-Path $pluginRoot "skills\using-superpowers\SKILL.md"
+if (-not (Test-Path $skillFile)) {
+    $output = @{
+        hookSpecificOutput = @{
+            hookEventName = "SessionStart"
+            additionalContext = "Error reading using-superpowers skill"
+        }
+    }
+    $output | ConvertTo-Json -Compress
+    exit 1
+}
+
+$usingSuperpowersContent = Get-Content $skillFile -Raw
+
+# Build the additional context
+$additionalContext = @"
+<EXTREMELY_IMPORTANT>
+You have superpowers.
+
+**The content below is from skills/using-superpowers/SKILL.md - your introduction to using skills:**
+
+$usingSuperpowersContent
+
+$warningMessage
+</EXTREMELY_IMPORTANT>
+"@
+
+# Output context injection as JSON
+$output = @{
+    hookSpecificOutput = @{
+        hookEventName = "SessionStart"
+        additionalContext = $additionalContext
+    }
+}
+
+$output | ConvertTo-Json -Depth 10
+exit 0

lib/initialize-skills.ps1

@@ -0,0 +1,102 @@
+# Initialize or update superpowers skills repository (Windows PowerShell version)
+
+$skillsDir = Join-Path $env:USERPROFILE ".config\superpowers\skills"
+$skillsRepo = "https://github.com/obra/superpowers-skills.git"
+
+# Check if skills directory exists and is a valid git repo
+if (Test-Path (Join-Path $skillsDir ".git")) {
+    Set-Location $skillsDir
+
+    # Get the remote name for the current tracking branch
+    $trackingFull = git rev-parse --abbrev-ref --symbolic-full-name '@{u}' 2>$null
+    $trackingRemote = ""
+    if ($trackingFull) {
+        $trackingRemote = ($trackingFull -split '/')[0]
+    }
+
+    # Fetch from tracking remote if set, otherwise try upstream then origin
+    if ($trackingRemote) {
+        git fetch $trackingRemote 2>$null | Out-Null
+    } else {
+        git fetch upstream 2>$null | Out-Null
+        if ($LASTEXITCODE -ne 0) {
+            git fetch origin 2>$null | Out-Null
+        }
+    }
+
+    # Check if we can fast-forward
+    $local = git rev-parse '@' 2>$null
+    $remote = git rev-parse '@{u}' 2>$null
+    $base = git merge-base '@' '@{u}' 2>$null
+
+    # Try to fast-forward merge first
+    if ($local -and $remote -and ($local -ne $remote)) {
+        # Check if we can fast-forward (local is ancestor of remote)
+        if ($local -eq $base) {
+            # Fast-forward merge is possible - local is behind
+            Write-Host "Updating skills to latest version..."
+            $mergeOutput = git merge --ff-only '@{u}' 2>&1
+            if ($LASTEXITCODE -eq 0) {
+                Write-Host "✓ Skills updated successfully"
+                Write-Host "SKILLS_UPDATED=true"
+            } else {
+                Write-Host "Failed to update skills"
+            }
+        } elseif ($remote -ne $base) {
+            # Remote has changes (local is behind or diverged)
+            Write-Host "SKILLS_BEHIND=true"
+        }
+        # If REMOTE = BASE, local is ahead - no action needed
+    }
+
+    exit 0
+}
+
+# Skills directory doesn't exist or isn't a git repo - initialize it
+Write-Host "Initializing skills repository..."
+
+# Handle migration from old installation
+$oldGitDir = Join-Path $env:USERPROFILE ".config\superpowers\.git"
+if (Test-Path $oldGitDir) {
+    Write-Host "Found existing installation. Backing up..."
+    Move-Item $oldGitDir "$oldGitDir.bak" -Force -ErrorAction SilentlyContinue
+
+    $oldSkillsDir = Join-Path $env:USERPROFILE ".config\superpowers\skills"
+    if (Test-Path $oldSkillsDir) {
+        Move-Item $oldSkillsDir "$oldSkillsDir.bak" -Force -ErrorAction SilentlyContinue
+        Write-Host "Your old skills are in $env:USERPROFILE\.config\superpowers\skills.bak"
+    }
+}
+
+# Clone the skills repository
+$configDir = Join-Path $env:USERPROFILE ".config\superpowers"
+if (-not (Test-Path $configDir)) {
+    New-Item -ItemType Directory -Path $configDir -Force | Out-Null
+}
+
+git clone $skillsRepo $skillsDir
+
+Set-Location $skillsDir
+
+# Check if gh CLI is installed
+$ghExists = Get-Command gh -ErrorAction SilentlyContinue
+if ($ghExists) {
+    Write-Host ""
+    Write-Host "GitHub CLI detected. Would you like to fork superpowers-skills?"
+    Write-Host "Forking allows you to share skill improvements with the community."
+    Write-Host ""
+    $reply = Read-Host "Fork superpowers-skills? (y/N)"
+
+    if ($reply -match '^[Yy]$') {
+        gh repo fork obra/superpowers-skills --remote=true
+        Write-Host "Forked! You can now contribute skills back to the community."
+    } else {
+        git remote add upstream $skillsRepo
+    }
+} else {
+    # No gh, just set up upstream remote
+    git remote add upstream $skillsRepo
+}
+
+Write-Host "Skills repository initialized at $skillsDir"
+exit 0