PR Review Bot

AI-powered GitHub PR reviewer using a prompt chaining pipeline — classifier → parallel checks → synthesizer.

Architecture

PR opened
    │
    ▼
[1] Classifier          — what type of change is this?
    │
    ▼
[2] Parallel checks     — runs simultaneously
    ├── Security check
    ├── Logic check
    └── Quality check
    │
    ▼
[3] Synthesizer         — combines all results into final comment
    │
    ▼
GitHub comment posted

Setup

1. Clone & restore

git clone https://github.com/your-org/pr-review-bot
cd pr-review-bot
dotnet restore

2. Environment variables

Variable	Required	Description
ANTHROPIC_API_KEY	✅	From console.anthropic.com
GITHUB_TOKEN	✅	PAT with repo scope
WEBHOOK_SECRET	Recommended	Any random string

3. Run locally

$env:ANTHROPIC_API_KEY="sk-ant-..."
$env:GITHUB_TOKEN="ghp_..."
$env:WEBHOOK_SECRET="your-secret"
dotnet run

4. Expose via ngrok (dev only)

ngrok http 3000

5. GitHub Webhook

Settings → Webhooks → Add webhook:

• URL: https://your-domain.com/webhook
• Content type: application/json
• Secret: value of WEBHOOK_SECRET
• Events: Pull requests only

Production deploy

Railway (recommended — simplest)

railway init
railway up
railway variables set ANTHROPIC_API_KEY=... GITHUB_TOKEN=... WEBHOOK_SECRET=...

Docker

docker build -t pr-review-bot .
docker run -p 3000:3000 \
  -e ANTHROPIC_API_KEY=... \
  -e GITHUB_TOKEN=... \
  -e WEBHOOK_SECRET=... \
  pr-review-bot

Customizing the prompts

All prompts are in src/Prompts/ReviewPrompts.cs. Add your team's rules:

public const string QualityReviewer = """
    ...existing prompt...
    
    Additional rules for our team:
    - No magic numbers — use named constants
    - Repository methods must be async
    - Controllers must not contain business logic
    """;

Endpoints

Endpoint	Description
GET /	Version info
GET /health	Health check
POST /webhook	GitHub webhook receiver