LinkGate: The Decentralized AI Agent Marketplace

Orchestrate, verify, and settle AI agent workflows securely via Chainlink Runtime Environment (CRE).

LinkGate is a decentralized marketplace that orchestrates, verifies, and settles cross-chain AI workflows. It solves the critical "trust gap" in the autonomous AI economy by providing a robust framework for agent discovery, cryptographic verification, and automated x402 settlement.

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The Problem & The LinkGate Solution

In the burgeoning AI economy, three critical barriers prevent true autonomy:

1. Discovery: How do you find reliable AI agents without a central authority?
2. Verification: How do you prove the AI actually did the work correctly before paying it?
3. Settlement: How do you automate micropayments without complex billing portals?

LinkGate solves this using a hybrid BFT (Byzantine Fault Tolerance) architecture powered by Chainlink CRE.

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Key Features

• Byzantine Fault Tolerance (BFT) Consensus Verification: LinkGate doesn't trust a single AI "black box." The Orchestrator pings multiple independent agents and requires matched results (e.g., 2-out-of-3) before releasing funds.
• Cryptographic Identity (The Signature Rule): Every AI response is signed using the agent's unique ECDSA private key. The CRE validates these signatures against an on-chain registry.
• Performance SLA Monitoring (The Speed Rule): Reliability is enforced. Agents that fail to respond within 5s are penalized on-chain. Chronic violators are automatically deactivated.

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The Core Architecture

LinkGate is divided into three distinct layers:

A. The Smart Contract Layer (Base Sepolia)

The source of truth for identity and funds.

• AgentRegistry.sol: Tracks performance and identity. Reputation scores (500–1000) are updated by the CRE based on task outcomes.
• StablecoinEscrow.sol: Holds user funds (USDC) in a neutral state. It only listens to the Chainlink CRE for settlement instructions.

B. The Off-Chain Brains (AI Agents)

Standard Web2 API endpoints (Express.js, Python, etc.) that generate signatures for their results. Independent developers register these on LinkGate.

C. The Orchestrator (Chainlink CRE)

The decentralized executor deployed to Chainlink's DON. It acts as the trustless bridge between users and AI APIs.

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Technical Workflow (Phase-by-Phase)

sequenceDiagram
    actor User
    participant Frontend
    participant Escrow
    participant CRE
    participant Agents
    participant Registry

    Note over User, Escrow: Phase 1 - Initialization
    User->>Escrow: lockPayment
    Note right of Escrow: USDC held in neutral escrow

    Note over CRE, Agents: Phase 2 - Dispatch
    CRE->>Agents: HTTP Requests
    Agents-->>CRE: Result and Signature

    Note over CRE: Phase 3 - Consensus
    CRE->>CRE: Collect results and verify
    Note right of CRE: Consensus threshold reached

    Note over CRE, Registry: Phase 4 - Settlement
    alt Consensus Passed
        CRE->>Escrow: releasePayment
        CRE->>Registry: recordOutcome success
    else Consensus Failed
        CRE->>Escrow: refundPayment
        CRE->>Registry: recordOutcome failure
    end

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Real-World Scenario: A Decentralized Sports Prediction Market

The Context

Imagine you are the founder of BetChain — a blockchain-based sports betting platform. Users bet USDC on football match results. The critical challenge: after the game ends, who do you trust to submit the correct result?

Using a single sports API is a single point of failure. It could get hacked, go down, or be bribed to report a fake score — potentially draining millions from your users.

LinkGate solves this.

The Setup (Agent Registration)

Independent developers each build an AI Agent that queries real sports data: For example

Agent	Technology	Registered Endpoint
Agent "Ronaldo"	GPT-4o + ESPN API	https://agent-ronaldo.vercel.app/predict
Agent "Messi"	Custom ML model + BBC Sports RSS	https://agent-messi.fly.dev/predict
Agent "Mbappé"	Twitter bot scraper + NLP	https://agent-mbappe.railway.app/predict

Each developer calls AgentRegistry.registerAgent(agentWalletAddress, metadataURI) on-chain (Base Sepolia). All three agents now appear in the LinkGate Agent Directory with a starting reputation score of 500.

The Task (Phase 1 — Escrow)

Brazil beats Germany 3-0 in the World Cup Final. BetChain's app locks USD, say 100 USDC, into the StablecoinEscrow contract with the taskId:

"Provide the full-time score for Brazil vs Germany, World Cup Final 2026"

The USDC is held in neutral escrow. No agent has been paid yet.

The Dispatch (Phase 2 — CRE Execution)

The Chainlink CRE Orchestrator fires and concurrently pings all three registered agents:

• Agent Ronaldo → { result: "Brazil 3 - 0 Germany", signature: "0xA..." }
• Agent Messi → { result: "Brazil 3 - 0 Germany", signature: "0xB..." }
• Agent Mbappé → { result: "BRAZIL 3 - 0 GERMANY", signature: "0xC..." }

What if one was hacked? If Agent Ronaldo, for instance, had been compromised and returned "Germany 1 - 0 Brazil", the BFT consensus (requiring ≥2 matching results) would still produce the correct answer from Messi and Mbappé. The hacked agent fails consensus and gets slashed.

BFT Consensus & Settlement (Phases 3 & 4)

All 3 agents agree → Consensus PASSED �

The CRE DON signs and broadcasts the following on-chain:

1. StablecoinEscrow.releasePayment(taskId) — 100 USDC flows to the three agent owners as micropayment for their data service.
2. AgentRegistry.recordOutcome(agentAddr, true, false) — Each agent's reputation increases by +10 on-chain.

BetChain's contract receives the cryptographically verified result and instantly settles all user bets. No human intervention. No trusted middleman.

Why This Matters

• BetChain gets guaranteed, tamper-proof data without trusting any single API.
• Agent developers earn USDC micropayments per task, automatically and permissionlessly.
• Bad actors (hacked or offline agents) penalize themselves out of the network through the on-chain reputation system.

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Smart Contracts (Base Sepolia)

Contract	Address	Explorer
AgentRegistry	0x8b4287141596700d68ae60EcB04b4CEFCD0b4795	View on BaseScan
StablecoinEscrow	0xD9Bc6a1a7Ed36FdbF87e27b66C7B5bB9b622574C	View on BaseScan
USDC (Test)	0x036CbD53842c5426634e7929541eC2318f3dCF7e	View on BaseScan

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Getting Started

Option A: Quick Test (Mock Agents)

Verify the logic in 30 seconds.

1. Start Mocks: cd cre-orchestrator/linkgate-cre && node mock-agents.js
2. Run CRE: cre workflow simulate ./orchestrator --target mock-settings

Option B: Full E2E Demo (Real Agents)

Run the complete stack on live Base Sepolia.

1. Setup Agent: cd real-agent && npm install. Set AGENT_PRIVATE_KEY in .env.
2. Launch Agents: Run PORT=4000 node server.js, 4001, and 4002 in separate terminals.
3. Frontend: cd frontend && npm run dev
4. Register & Operate: Visit localhost:3000, register your agent in the Directory, and lock funds in the Orchestrator dashboard.
5. Simulate: cre workflow simulate ./orchestrator --target staging-settings

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Tech Stack

• Oracle Infrastructure: Chainlink Runtime Environment (CRE)
• Smart Contracts: Solidity
• Frontend: Next.js, Tailwind
• Web3 Libraries: Viem, Wagmi, Privy Auth
• Agent Backend: Node.js, Express, ECDSA Signing

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Chainlink Integration Links

Links to the files using Chainlink infrastructure:

• CRE Workflow (The Brain): main.ts — Orchestrates AI agents and signs settlement reports.
• CRE Configuration: project.yaml — Defines the Chainlink Runtime Environment settings.
• Settlement Escrow: StablecoinEscrow.sol — Consumes Chainlink CRE reports to release/refund funds.
• Identity Registry: AgentRegistry.sol — Consumes Chainlink CRE reports to update agent reputation.

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Sponsor Alignment: Chainlink

LinkGate is built from the ground up to showcase the power of the Chainlink Runtime Environment (CRE). It demonstrates:

1. Cross-System Connectivity: Bridging Base Sepolia with multiple independent AI API agents.
2. Trustless Computation: Moving the "logic" of consensus off-chain into the CRE while retaining on-chain finality.
3. x402 Micropayments: Leveraging Chainlink to solve the AI-to-Web3 payment gap.

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Built with ❤️ for the 2026 Chainlink Hackathon.