PreMerge Review

PreMerge Review is a Visual Studio Code extension that helps developers perform AI-assisted code reviews before merging their feature branches. It generates a smart review prompt from the Git diff between branches, optionally using your team's custom review instructions.

Demo

🚀 Features

• 📍 Branch Comparison: Compare your current branch with a target base branch (e.g., dev)
• 🧾 Git Diff Generation: Generate a full Git diff (git diff base...feature)
• 📘 Custom Instructions: Read custom instructions from .github/instructions/
• ✍️ AI Review Prompt: Automatically build a review prompt from diff + instruction
• 🤖 AI Integration: Send the prompt to Copilot for review suggestions
• 📊 Visual Diff Viewer: Interactive diff viewer with syntax highlighting
• 📤 Slack Integration: (Optional) Notify the team with review results via Slack
• 💾 Export Functionality: Export diffs to files for sharing

🛠️ Usage

Basic Review Workflow

1. Open Project: Open any Git-enabled project in VSCode
2. Open Extension: Click the PreMerge Review tab in the primary sidebar
3. Select Branches:
   • Choose your current branch (feature branch)
   • Select your target branch (e.g., dev, main)
   • Optionally select a specific commit for more precise comparison
4. Create Review: Click Create Review to generate diff
5. View Results:
   • Click Show Details to open the Visual Diff Viewer
   • Click Process Review to get AI feedback via Copilot
   • Click Post to Slack to share results with your team

Commands Available

• PreMerge Review: Show Diff Viewer - Open diff viewer for current review
• PreMerge Review: Export Diff - Export current diff to file
• PreMerge Review: Test Slack Connection - Test Slack webhook integration
• PreMerge Review: Show Review Data - Display current review summary

⚙️ Configuration

Extension Settings

Configure the extension via VS Code settings (Ctrl+, → search "premerge"):

{
  // Instruction files for review guidance
  "premergeReview.instructionFiles": [
    ".github/instructions.md",
    ".github/review-instructions.md",
    "docs/review-guidelines.md"
  ],
  
  // Maximum size for instruction files (1MB default)
  "premergeReview.maxInstructionFileSize": 1048576,
  
  // Slack webhook URL for notifications
  "premergeReview.slack.webhookUrl": "https://hooks.slack.com/services/YOUR/WEBHOOK/URL",
  
  // Maximum tokens per AI request part
  "premergeReview.maxTokensPerPart": 8000
}

Review Instructions

Create instruction files to guide the AI review process:

.github/instructions.md example:

# Code Review Guidelines

## Focus Areas
- Security vulnerabilities
- Performance implications
- Code maintainability
- Test coverage
- Documentation completeness

## Coding Standards
- Follow TypeScript/JavaScript best practices
- Use meaningful variable names
- Add JSDoc comments for public APIs
- Ensure proper error handling

## Specific Checks
- [ ] No hardcoded credentials
- [ ] Proper input validation
- [ ] Memory leak prevention
- [ ] Accessibility compliance

🔧 Technical Requirements

Essential Requirements

• VS Code: Version 1.102.0 or higher
• Git: Installed and accessible in PATH
• GitHub Copilot Extension: Required for AI review functionality
  • Install from VS Code Marketplace: GitHub.copilot
  • Must be signed in with valid GitHub Copilot subscription
  • Extension must be active and enabled

Optional Requirements

• Slack Webhook: For team notifications (optional)
• Node.js: For development and building (development only)

GitHub Copilot Setup

1. Install GitHub Copilot Extension:

   code --install-extension GitHub.copilot
   

   Or search "GitHub Copilot" in VS Code Extensions

2. Sign In: Follow prompts to sign in with your GitHub account

3. Verify Setup: Check that Copilot is active in VS Code status bar

⚠️ Important: Without GitHub Copilot extension, the AI review functionality will not work. The extension will show error messages when trying to process reviews.

🔍 Troubleshooting

Common Issues

"No review data available"

• Ensure you've created a review first using the sidebar
• Check that your workspace is a valid Git repository

"Git error" messages

• Verify Git is installed and accessible
• Ensure you're in a Git repository with commits
• Check that selected branches exist

GitHub Copilot Issues

• Extension not found: Install GitHub Copilot extension from VS Code Marketplace
• Not signed in: Sign in to GitHub with valid Copilot subscription
• Extension disabled: Enable GitHub Copilot in Extensions panel
• Subscription expired: Verify your GitHub Copilot subscription status
• Request failures: Check VS Code Developer Console (Help → Toggle Developer Tools) for error messages
• Rate limiting: Wait a few minutes if you've exceeded API limits

AI Review not working

• Ensure GitHub Copilot extension is installed and active (check status bar)
• Verify you're signed in to GitHub with a valid Copilot subscription
• Try restarting VS Code if Copilot stopped responding
• Check that the extension has access to send chat requests

Slack integration not working

• Verify webhook URL is correct and active
• Test connection using the "Test Slack Connection" command
• Check Slack workspace permissions

Performance Tips

• For large diffs, the extension automatically splits requests into manageable parts
• Consider excluding binary files or large assets from review
• Use specific commit ranges for focused reviews

📸 UI Preview

📈 Roadmap

• [ ] Multiple AI Providers: Support for OpenAI, Claude, etc.
• [ ] Custom Review Templates: Predefined review types
• [ ] Team Collaboration: Share reviews within teams
• [ ] Review History: Track and compare previous reviews
• [ ] Integration: GitHub/GitLab PR integration
• [ ] Advanced Filtering: File type and change size filters

🤝 Contributing

We welcome contributions! Please see our contributing guidelines for more information.

Development Setup

# Clone the repository
git clone https://github.com/your-username/premerge-review.git

# Install dependencies
cd premerge-review
npm install

# Build the extension
npm run compile
npm run build-webview

# Run tests
npm test

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙋‍♂️ Support

• Issues: Report bugs or request features on GitHub
• Discussions: Join our community discussions
• Documentation: Check our wiki for detailed guides

Happy reviewing! 🚀