Keryx — Pay-Per-Citation AI Agent

Lepton Agents Hackathon submission (Canteen × Circle) — Live Demo

Keryx is the first AI agent that pays publishers every time it cites their work, using Circle's x402 micropayment protocol on the Arc Testnet. It is a full toll layer for the agent-first internet.

The Problem

AI agents consume publisher content at scale to answer user questions — often without compensating the original creators. Keryx solves this with a machine-to-machine payment rail: every citation costs the agent a small USDC fee, which flows instantly to the publisher's wallet.

How It Works

User asks a question
       ↓
Agent identifies knowledge gaps (Groq / Llama 3.3)
       ↓
Agent fetches free previews of candidate articles
       ↓
Agent decides: PAY or SKIP based on relevance
       ↓
Circle Gateway pays the cite endpoint via x402 (Arc Testnet)
       ↓
Publisher receives USDC; citation receipt stored on-chain
       ↓
Agent integrates paid content into final answer

Key Features

Tech Stack

Environment Variables

Create a .env.local file:

NEXT_PUBLIC_SUPABASE_URL=
NEXT_PUBLIC_SUPABASE_PUBLISHABLE_KEY=
SUPABASE_SERVICE_ROLE_KEY=
ARC_TESTNET_RPC=
SELLER_ADDRESS=
SELLER_PRIVATE_KEY=
BUYER_ADDRESS=
BUYER_PRIVATE_KEY=
GROQ_API_KEY=
NEXT_PUBLIC_BASE_URL=
CRON_SECRET=          # Optional: secures /api/cron endpoint

Running Locally

npm install
npm run dev
# Navigate to http://localhost:3000

Deployment

Configured for Vercel. All env vars must be set in the Vercel dashboard. The vercel.json configures a cron job to refresh RSS feeds every hour automatically.

[!WARNING] Security Disclaimer — This is a hackathon prototype for the Arc Testnet only.

• Private Keys: The buyer agent's private key is read from environment variables in the serverless function. This is not safe for production. A real system must use a KMS or MPC wallet..
• Domain Verification: DNS TXT verification is implemented but can be bypassed via DEMO_MODE=true. Disable this for production.
• Do not use with real funds.

Hackathon Submission — This project incorporates components from the arc-nanopayments sample to demonstrate x402 Gateway capabilities natively in a Next.js App Router environment.