PR Guardian AI

AI-Powered Pull Request Reviewer for GitHub

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Overview

PR Guardian AI is an advanced GitHub App that automatically reviews pull requests using artificial intelligence. It reads your code diffs, finds problems, and writes professional comments inside the PR, just like a human reviewer.

This tool helps developers deliver high-quality code faster, reduces review workload, and provides consistent feedback across teams.

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Why PR Guardian AI?

Features

Feature	Description
AI-powered Code Review	Automatically analyzes PR diffs using OpenAI.
Detects Code Issues	Finds bugs, security risks, optimization issues, unused code, etc.
Comments Inside PR	Posts human-like comments directly in the conversation.
Real-Time Webhook Processing	Handles PR events instantly (opened, updated).
Secure GitHub App Authentication	Uses JWT & installation token best practices.
Works on Any Repository	Easy installation & setup.
Developer Friendly	Fully open-source & customizable.

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How It Works (Full Explanation)

1. A Pull Request is created or updated

GitHub triggers a webhook event: pull_request with action opened, synchronize, etc.

2. GitHub sends PR data to your backend

Your backend receives it on:

POST /webhook

It contains:

• PR number
• repo information
• diff URL
• installation ID

3. The backend validates the signature

Using X-Hub-Signature-256 and your GITHUB_WEBHOOK_SECRET.

4. Backend authenticates as GitHub App

It generates:

• JWT
• Installation Access Token

5. Backend fetches the PR diff

Using:

https://patch-diff.githubusercontent.com/raw/.../pull/<id>.diff

6. AI analyzes the code diff

It sends diff to OpenAI with a structured prompt:

• detect bugs
• find performance issues
• detect bad naming
• security warnings
• suggest improvements

7. App posts comments in the PR

Using:

POST /repos/{owner}/{repo}/issues/{pr_number}/comments

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Architectural Diagram

 ┌──────────────┐
 │ Developer    │
 │ creates PR   │
 └──────┬───────┘
        │
        ▼
 ┌────────────────────┐
 │ GitHub Webhook     │────────────┐
 └──────┬─────────────┘            │
        │ (pull_request event)     │
        ▼                          │
 ┌───────────────────────┐         │
 │ FastAPI Backend       │         │
 │ /webhook              │         │
 └──────┬────────────────┘         │
        │                          │
        ▼                          │
 ┌─────────────────────────┐       │
 │ Verify Signature        │       │
 └──────┬──────────────────┘       │
        │                          │
        ▼                          │
 ┌─────────────────────────────┐   │
 │ Generate GitHub JWT         │   │
 │ Get Installation Token      │   │
 └──────┬──────────────────────┘   │
        │                          │
        ▼                          │
 ┌──────────────────────────────┐  │
 │ Fetch PR diff (.diff)        │  │
 └──────┬───────────────────────┘  │
        │                          │
        ▼                          │
 ┌────────────────────────────┐    │
 │ Send code to OpenAI        │    │
 │ AI Review Engine           │    │
 └──────┬─────────────────────┘    │
        │                          │
        ▼                          │
 ┌─────────────────────────────┐   │
 │ GitHub API: Post Comment    │◄──┘
 │ inside Pull Request         │
 └─────────────────────────────┘

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Installation (Developer Mode)

1. Clone repo

git clone https://github.com/AmirhosseinHonardoust/PR-Guardian-AI.git
cd github-ai-reviewer

2. Install requirements

pip install -r requirements.txt

3. Create .env

GITHUB_APP_ID=123456
GITHUB_PRIVATE_KEY_PATH=./private-key.pem
GITHUB_WEBHOOK_SECRET=your-secret
OPENAI_API_KEY=your-key
LOG_LEVEL=info

4. Run server

uvicorn app.main:app --host 0.0.0.0 --port 8000

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Webhook Proxy (Local Development)

Using Smee.io

npm install --global smee-client

smee --url https://smee.io/YOUR_ID --target http://localhost:8000/webhook

GitHub → App settings → Webhook URL

https://smee.io/YOUR_ID

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Deployment Options

Platform	Status	Difficulty
Railway	Recommended	Easy
Render	Works well	Medium
DigitalOcean Droplet		Medium
Heroku	Requires paid Dyno
VPS / Bare-metal	Full control

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Testing

Create or update a pull request → Check PR conversation → AI comments should appear automatically.

If not:

• Check GitHub delivery logs
• Check backend logs
• Check Smee console

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Contributing

Pull requests are welcome.

You can contribute:

• Better AI prompts
• Support for multiple file types
• Line-by-line review
• Security scanning
• Performance analysis

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License

Distributed under the MIT License.

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Credits

Built with care by Amir Hossein Honardoust Helping developers write clean, optimized, and secure code using AI.

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