fix: add cross-platform commit helper to resolve heredoc issues

Resolves the issue where git commit commands with heredoc syntax fail on Windows
systems. The heredoc approach (<<'EOF') only works in bash/Unix shells and causes
"pathspec '<<'EOF'' did not match any file(s)" errors on Windows.

Changes:
- Add scripts/commit-helper.ts: Cross-platform script using temporary files
- Add npm script "commit" for easy access: npm run commit "message"
- Update system prompt to instruct AI agents to use commit helper
- Replace platform-specific heredoc instructions with single helper approach

The commit helper validates git repository state, handles multi-line messages
correctly, and works consistently across Windows, macOS, and Linux.

🤖 Generated with Codebuff
Co-Authored-By: Codebuff <noreply@codebuff.com>

Author: PierrunoYT

backend/src/system-prompt/prompts.ts

@@ -278,28 +278,24 @@ When the user requests a new git commit, please follow these steps closely:
    Generated with Codebuff 🤖
    Co-Authored-By: Codebuff <noreply@codebuff.com>
    \`\`\`
-   To maintain proper formatting, use cross-platform compatible commit messages:
+   To maintain proper formatting and ensure cross-platform compatibility, use the commit helper script:
    
-   **For Unix/bash shells:**
    \`\`\`
-   git commit -m "$(cat <<'EOF'
-   Your commit message here.
+   npm run commit "Your commit message here.
 
    🤖 Generated with Codebuff
-   Co-Authored-By: Codebuff <noreply@codebuff.com>
-   EOF
-   )"
+   Co-Authored-By: Codebuff <noreply@codebuff.com>"
    \`\`\`
    
-   **For Windows Command Prompt:**
+   Or directly with bun:
    \`\`\`
-   git commit -m "Your commit message here.
+   bun scripts/commit-helper.ts "Your commit message here.
 
    🤖 Generated with Codebuff
    Co-Authored-By: Codebuff <noreply@codebuff.com>"
    \`\`\`
    
-   Always detect the platform and use the appropriate syntax. HEREDOC syntax (\`<<'EOF'\`) only works in bash/Unix shells and will fail on Windows Command Prompt.
+   **IMPORTANT**: Always use the commit helper script instead of direct git commit commands with heredoc syntax, as heredocs (\`<<'EOF'\`) fail on Windows systems. The commit helper handles multi-line messages correctly on all platforms.
 
 **Important details**
 

package.json

@@ -35,7 +35,8 @@
     "test": "bun --filter='{@codebuff/backend,@codebuff/common,@codebuff/npm-app,@codebuff/agents}' run test",
     "init-worktree": "bun scripts/init-worktree.ts",
     "cleanup-worktree": "bash scripts/cleanup-worktree.sh",
-    "generate-tool-definitions": "bun scripts/generate-tool-definitions.ts"
+    "generate-tool-definitions": "bun scripts/generate-tool-definitions.ts",
+    "commit": "bun scripts/commit-helper.ts"
   },
   "dependencies": {
     "@t3-oss/env-nextjs": "^0.7.3",

scripts/commit-helper.ts

@@ -0,0 +1,98 @@
+#!/usr/bin/env bun
+
+/**
+ * Cross-platform Git commit helper that properly handles multi-line commit messages
+ * 
+ * This script solves the issue where heredoc syntax (<<'EOF') fails on Windows systems.
+ * It creates a temporary file to hold the commit message, which works consistently
+ * across all platforms.
+ * 
+ * Usage: bun scripts/commit-helper.ts "Your multi-line commit message here"
+ */
+
+import { execSync } from 'child_process'
+import { writeFileSync, unlinkSync, existsSync } from 'fs'
+import { tmpdir } from 'os'
+import { join } from 'path'
+
+function createCommit(message: string): void {
+  // Validate that we're in a git repository
+  try {
+    execSync('git rev-parse --git-dir', { stdio: 'ignore' })
+  } catch (error) {
+    console.error('❌ Error: Not in a git repository')
+    process.exit(1)
+  }
+
+  // Check if there are changes to commit
+  try {
+    const status = execSync('git status --porcelain', { encoding: 'utf8' })
+    if (status.trim() === '') {
+      console.error('❌ Error: No changes to commit')
+      process.exit(1)
+    }
+  } catch (error) {
+    console.error('❌ Error: Failed to check git status')
+    process.exit(1)
+  }
+
+  // Create a temporary file to hold the commit message
+  const tempFile = join(tmpdir(), `git-commit-msg-${Date.now()}-${Math.random().toString(36).substring(7)}.txt`)
+  
+  try {
+    // Write the message to the temp file
+    writeFileSync(tempFile, message.trim(), 'utf8')
+    
+    // Use git commit with -F flag to read from file
+    execSync(`git commit -F "${tempFile}"`, { 
+      stdio: 'inherit',
+      encoding: 'utf8'
+    })
+    
+    console.log('✅ Commit created successfully!')
+  } catch (error) {
+    if (error instanceof Error) {
+      console.error('❌ Commit failed:', error.message)
+    } else {
+      console.error('❌ Commit failed with unknown error')
+    }
+    process.exit(1)
+  } finally {
+    // Clean up temp file
+    try {
+      if (existsSync(tempFile)) {
+        unlinkSync(tempFile)
+      }
+    } catch (cleanupError) {
+      // Ignore cleanup errors, but warn
+      console.warn('⚠️  Warning: Failed to clean up temporary file:', tempFile)
+    }
+  }
+}
+
+// Main execution
+function main(): void {
+  // Get commit message from command line argument
+  const message = process.argv[2]
+
+  if (!message) {
+    console.error('Usage: bun scripts/commit-helper.ts "Your commit message here"')
+    console.error('       npm run commit "Your commit message here"')
+    console.error('')
+    console.error('Example:')
+    console.error('  bun scripts/commit-helper.ts "fix: resolve authentication issue')
+    console.error('')
+    console.error('  Fixes login flow by updating token validation logic')
+    console.error('')  
+    console.error('  🤖 Generated with Codebuff')
+    console.error('  Co-Authored-By: Codebuff <noreply@codebuff.com>"')
+    process.exit(1)
+  }
+
+  createCommit(message)
+}
+
+// Execute if running as main module
+if (import.meta.main) {
+  main()
+}