🤖 PR Reviewer Bot with Google Gemini

Automated GitHub Pull Request code review bot powered by Google Gemini.
This webhook intelligently analyzes PR changes and comments on code style, potential refactoring, and best practices — using an LLM context-driven approach inspired by MCP (Model Context Protocol) patterns.

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✨ Features

• 🔍 Code Diff Analysis – Parses PR diffs to understand file changes
• 🤖 Gemini AI Integration – Uses Google's Gemini model to generate intelligent code reviews
• 🧠 Suggests Improvements – Code refactoring tips, lint issues, and mitigation suggestions
• 🧵 Autocomments on PR – Posts feedback as comments on the PR automatically
• 🔌 GitHub Webhook Friendly – Easily pluggable into any GitHub repo
• ♻️ Inspired by Agentic AI patterns and future MCP-style orchestration

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📦 Tech Stack

• Node.js + Express
• Google Gemini API (via REST)
• GitHub REST API
• serverless-http + Vercel compatible
• dotenv + body-parser

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🚀 Getting Started

🛠️ How It Works

1. GitHub triggers webhook when a Pull Request is opened/updated
2. Bot parses the changed files
3. Sends file diffs as prompts to Gemini
4. Receives code review suggestions
5. Posts review comments back on the PR

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🔗 How to Integrate in Your GitHub Repo

✅ Step 2: Add a Webhook to Your GitHub Repo

webhook URL : https://pr-reviewer-bot.vercel.app/webhook

1. Go to your GitHub repository
2. Navigate to Settings → Webhooks → Add webhook
3. Fill the fields:

Field	Value
Payload URL	https://pr-reviewer-bot.vercel.app/webhook
Content type	application/json
Secret	Your GITHUB_APP_SECRET
Events to trigger	✅ Pull requests

NOTE : to add GITHUB_APP_SECRET contact me on mail : Contact

4. Click Add Webhook

✅ Step 3: That’s it!

Now, when a contributor opens or updates a PR, the bot will:

• Read the diff
• Ask Gemini to review it
• Post feedback as comments

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🧪 Example curl Test (For Vercel Deployed Webhook)

curl -X POST [https://pr-reviewer-bot.vercel.app/webhook](https://pr-reviewer-bot.vercel.app/webhook) \
  -H "Content-Type: application/json" \
  -H "X-Hub-Signature-256: sha256=<signature>" \
  -d @mock-pr-payload.json

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📁 Project Structure

.
├── src/
│   ├── github.ts          # GitHub API logic
│   ├── gemini.ts          # Gemini API integration
│   └── verifySignature.ts # Signature validation
│   └── app.ts             # Main app logic
└── .env

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🧠 Inspired by AI Design Patterns

This bot is modeled after the Agentic AI pattern, with future compatibility for Anthropic’s Model Context Protocol (MCP).
It lays the foundation for context-rich, multi-step, tool-integrated AI workflows.

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🙌 Contributing

Want to add:

• Claude or GPT support?
• Custom review templates?
• Feedback loop with AI self-evaluation?

Feel free to open an issue or PR!

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📄 License

MIT

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👤 Author

Built with ❤️ by @tamojit-123

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