Claude PR Reviewer

A GitHub App that automatically reviews pull requests using Claude AI.

Features

• Automated PR Reviews: Triggered when requested as a reviewer
• Severity Classification: Critical, High, Medium, Low findings
• Smart Blocking: Only critical issues block PRs
• Re-review Support: Tracks fixed issues across reviews
• GitHub Suggestions: Uses native suggestion blocks for fixes

Architecture

GitHub Webhook → API Gateway → Lambda → ECS Fargate (Claude CLI)
                                              ↓
                                        GitHub API

Setup

Prerequisites

• AWS Account with CDK bootstrapped
• GitHub organization admin access
• Anthropic API key

1. Deploy Infrastructure

# Install dependencies
pnpm install

# Build the project
pnpm build

# Deploy to AWS
pnpm cdk:deploy

2. Create GitHub App

1. Go to your GitHub organization settings

2. Navigate to Developer settings → GitHub Apps

3. Click "New GitHub App"

4. Configure:

   • Name: Claude PR Reviewer
   • Homepage URL: Your organization URL
   • Webhook URL: Use the WebhookUrl output from CDK
   • Webhook secret: Generate a secure secret
   • Permissions:
     • Pull requests: Read & Write
     • Contents: Read
     • Metadata: Read
   • Events:
     • Pull request
     • Pull request review

5. After creation, note the App ID and generate a private key

3. Configure Secrets

Update the AWS Secrets Manager secrets with your values:

# GitHub App credentials
aws secretsmanager put-secret-value \
  --secret-id claude-pr-reviewer/github-app \
  --secret-string '{"appId":"YOUR_APP_ID","privateKey":"YOUR_PRIVATE_KEY"}'

# Anthropic API key
aws secretsmanager put-secret-value \
  --secret-id claude-pr-reviewer/anthropic \
  --secret-string '{"apiKey":"YOUR_ANTHROPIC_API_KEY"}'

# Config (use the command from CDK output)
aws secretsmanager put-secret-value \
  --secret-id claude-pr-reviewer/config \
  --secret-string '{"webhookSecret":"YOUR_WEBHOOK_SECRET",...}'

4. Build and Push Docker Image

# Get ECR login
aws ecr get-login-password --region us-east-1 | docker login --username AWS --password-stdin YOUR_ACCOUNT.dkr.ecr.us-east-1.amazonaws.com

# Build image
docker build -t claude-pr-reviewer .

# Tag and push
docker tag claude-pr-reviewer:latest YOUR_ECR_URI:latest
docker push YOUR_ECR_URI:latest

5. Install GitHub App

1. Go to your GitHub App settings
2. Click "Install App"
3. Select the repositories to enable

Usage

Trigger a Review

Request the bot as a reviewer on any PR:

1. Open a PR
2. Click "Reviewers" in the sidebar
3. Select your Claude PR Reviewer app

Labels

Label	Meaning
ai-review-pending	Review in progress
ai-reviewed	Review complete

Review Actions

Findings	GitHub Action
Any Critical	Request Changes
High only	Comment
Medium/Low only	Approval comment

Comment Format

Each finding is posted as a PR review comment with:

• Severity indicator (🔴 Critical, 🟠 High, 🟡 Medium, 🔵 Low)
• Category (Security, Performance, Logic, etc.)
• Description and fix suggestion
• Confidence level and reasoning
• References when applicable

Configuration

Environment variables for the Fargate task:

Variable	Description	Default
MAX_FILES_THRESHOLD	Skip PRs with more files	100
RETRY_ON_ERROR	Retry once on failure	true

Development

# Install dependencies
pnpm install

# Run type checking
pnpm typecheck

# Run tests
pnpm test

# Lint code
pnpm lint

# Format code
pnpm format

License

MIT