How I Built an AI Agent That Earns $150 Reviewing Pull Requests

What if your code could write code that earns money? That's exactly what I built: a PR Review Agent that autonomously reviews GitHub pull requests and claims bounties in cryptocurrency.

In this article, I'll walk you through how I built claude-review-agent, a CLI tool that fetches GitHub PR diffs, generates structured code reviews, and earned me a $150 bounty.

The Problem

Open source maintainers are overwhelmed. PRs pile up, reviews take hours, and contributors wait days for feedback. What if an AI could handle the first-pass review?

RustChain, a DePIN blockchain project, had a bounty for exactly this:

"Build a CLI tool that reviews PRs and posts structured comments"

Reward: $150 in RTC tokens

The Solution: claude-review-agent

I built a Node.js CLI tool that:

1. Fetches PR diffs via GitHub API
2. Generates structured reviews using Claude AI
3. Posts comments directly on PRs
4. Outputs Markdown for easy reading

Architecture

┌─────────────┐     ┌──────────────┐     ┌─────────────┐
│ GitHub API  │────▶│   claude-    │────▶│   Claude    │
│  (PR diff)  │     │  review.js   │     │     AI      │
└─────────────┘     └──────────────┘     └─────────────┘
                           │
                           ▼
                    ┌──────────────┐
                    │   Markdown   │
                    │   Review     │
                    └──────────────┘

Step 1: Parse the PR URL

First, we need to extract owner, repo, and PR number from the URL:

function parsePrUrl(url) {
  const match = url.match(/github\.com\/([^/]+)\/([^/]+)\/pull\/(\d+)/);
  if (!match) throw new Error('Invalid GitHub PR URL');
  return {
    owner: match[1],
    repo: match[2],
    prNumber: parseInt(match[3])
  };
}

Step 2: Fetch the PR Diff

Using the GitHub API with Accept: application/vnd.github.v3.diff header:

function fetchPrDiff(owner, repo, prNumber, token) {
  const diff = execSync(
    `curl -s -L -H "Authorization: Bearer ${token}" ` +
    `-H "Accept: application/vnd.github.v3.diff" ` +
    `"https://api.github.com/repos/${owner}/${repo}/pulls/${prNumber}"`,
    { encoding: 'utf-8', maxBuffer: 10 * 1024 * 1024 }
  );
  return diff;
}

Step 3: Generate the Review

Here's where Claude AI shines. We send the diff and ask for structured analysis:

const prompt = `You are an expert code reviewer. Analyze this PR diff and provide:

## Summary
Brief overview of changes (2-3 sentences)

## Risks
List potential issues or concerns (bulleted list)

## Suggestions
Improvement recommendations (bulleted list)

## Confidence
Rate your confidence: High/Medium/Low

Diff:
${diff}`;

const response = await anthropic.messages.create({
  model: 'claude-3-5-sonnet-20241022',
  max_tokens: 4096,
  messages: [{ role: 'user', content: prompt }]
});

Step 4: Output Formats

The tool supports multiple output modes:

# Print to console
claude-review --pr https://github.com/owner/repo/pull/123

# Save to file
claude-review --pr https://github.com/owner/repo/pull/123 --output review.md

# Post as PR comment
claude-review --pr https://github.com/owner/repo/pull/123 --post

Example Output

Here's a real review from testing on awesome-depin PR #28:

## Summary
This PR adds RustChain to the DePIN infrastructure list. It's a minimal 
addition of one entry under the L1/L2 category with project description 
and links.

## Risks
- Low complexity change, minimal risk
- Link validation should be verified

## Suggestions
- Consider adding a brief note about the Proof-of-Antiquity mechanism
- The description could mention supported hardware architectures

## Confidence
Medium

Testing on Real PRs

I tested the agent on two real pull requests:

PR	Repository	Result
#28	iotexproject/awesome-depin	✅ Review generated
#2372	rust-unofficial/awesome-rust	✅ Review generated

Both tests produced meaningful, actionable feedback.

The Bounty Submission

After testing, I submitted the tool to the RustChain bounty issue:

Repository: https://github.com/ZG361/claude-review-agent

Acceptance criteria met:

• ✅ Works via CLI
• ✅ Structured Markdown output
• ✅ Tested on 2 real PRs
• ✅ README with setup/usage instructions

Result: $150 bounty claimed!

Installation

Want to use it yourself?

# Clone the repo
git clone https://github.com/ZG361/claude-review-agent
cd claude-review-agent

# Install dependencies
npm install

# Set environment variables
export GH_TOKEN=your_github_token
export ANTHROPIC_API_KEY=your_anthropic_key

# Run
node bin/claude-review.js --pr https://github.com/owner/repo/pull/123

Lessons Learned

1. Start with the acceptance criteria - Read the bounty requirements carefully before coding
2. Test on real data - Use actual PRs to validate your tool works
3. Template mode is useful - When you don't have API access, generate structured templates
4. Document everything - A good README is half the battle

What's Next?

The agent is just the beginning. Future improvements could include:

• Multi-language support for non-English reviews
• Custom review templates per repository
• Integration with CI/CD for automated reviews on every PR
• Support for other AI providers (GPT-4, Gemini, etc.)

Conclusion

Building AI agents that earn cryptocurrency isn't science fiction—it's happening right now. The claude-review-agent took about 3 hours to build and earned $150 in RTC tokens.

The future of work is AI-assisted, and platforms like RustChain are creating the infrastructure for AI agents to participate in the economy.

Your old hardware might be worth more than you think—and so is your code.

---

Built with ❤️ and Claude AI. Check out RustChain for more bounties.

Wallet: ZG361