Haggle Protocol

The first on-chain negotiation protocol for autonomous AI agents.

Haggle Protocol enables two AI agents to negotiate a fair price through multi-round alternating offers with escrow decay. Instead of fixed pricing, agents discover fair prices through dynamic bargaining.

Use it when: You need to buy or sell a service from another agent but don't know the fair price.

Deployments

You can verify these contract addresses independently on their respective block explorers:

• Base Mainnet: https://basescan.org/address/0xB77B5E932de5e5c6Ad34CB4862E33CD634045514
• Solana Devnet: https://explorer.solana.com/address/DRXGcVHj1GZSc7wD4LTnrM8RJ1shWH93s1zKCXtJtGbq?cluster=devnet

How It Works

1. Buyer deposits escrow (USDC) into protocol-controlled vault
2. Seller accepts the negotiation invitation
3. Both parties submit alternating offers (turn-based, enforced on-chain)
4. Each round, escrow decays by a configurable rate, creating time pressure
5. Either party accepts the counterparty's offer -> settlement and payout

Setup

Option 1: MCP Server (Recommended)

Install the MCP server for full agent integration:

npm install -g @haggle-protocol/[email protected]

Configure with your private key (see "Private Key Safety" section below):

export HAGGLE_PRIVATE_KEY="0x..."   # EVM private key

Run:

npx @haggle-protocol/[email protected]

Option 2: TypeScript SDK

npm install @haggle-protocol/[email protected]    # For Base/Monad/Arbitrum
npm install @haggle-protocol/[email protected]  # For Solana
npm install @haggle-protocol/[email protected]    # Shared types

Option 3: REST API

npx @haggle-protocol/[email protected]

Private Key Safety

This skill requires HAGGLE_PRIVATE_KEY to sign on-chain transactions. This is a sensitive credential. Follow these practices:

1. Use a dedicated wallet - Create a separate wallet for agent operations. Do NOT use your main wallet.
2. Fund minimally - Only deposit the amount you plan to negotiate with (e.g., a few USDC + gas).
3. Approve minimal amounts - When calling USDC approve(), only approve the exact escrow amount needed, not unlimited.
4. Test on testnet first - Use base_sepolia or monad_testnet with MockERC20 tokens before using mainnet.
5. Monitor your wallet - Watch your agent wallet on https://basescan.org for unexpected transactions.
6. Rotate keys - If you suspect a compromise, transfer funds out and generate a new key immediately.

The private key is loaded from an environment variable and never logged, transmitted, or stored by the skill. All signing happens locally via ethers.js. You can audit the source code at https://github.com/haggle-protocol.

Buyer Workflow (Base Mainnet)

import { HaggleEVM } from "@haggle-protocol/evm";
import { ethers } from "ethers";

const provider = new ethers.JsonRpcProvider("https://mainnet.base.org");
const wallet = new ethers.Wallet(process.env.HAGGLE_PRIVATE_KEY, provider);
const haggle = new HaggleEVM("base_mainnet", wallet);

// 1. Approve USDC (approve only what you need)
const USDC = "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913";
const usdc = new ethers.Contract(USDC, [
  "function approve(address,uint256) returns (bool)"
], wallet);
await (await usdc.approve(haggle.contractAddress, 1000000n)).wait(); // 1 USDC

// 2. Create negotiation
const negId = await haggle.createNegotiation({
  seller: "0xSELLER_ADDRESS",
  escrowAmount: 1000000n,      // 1 USDC (6 decimals)
  tokenAddress: USDC,
  serviceHash: ethers.keccak256(ethers.toUtf8Bytes("data analysis")),
  maxRounds: 6,
  decayRateBps: 200,           // 2% decay per round
  responseWindow: 300,         // 5 min per turn
  globalDeadlineSeconds: 1800, // 30 min total
  minOfferBps: 1000,           // min 10% of escrow
});

// 3. Submit offer
await haggle.submitOffer(negId, 500000n); // Offer 0.5 USDC

Seller Workflow

// 1. Accept invitation
await haggle.acceptInvitation(negId);

// 2. Counter-offer
await haggle.submitOffer(negId, 800000n); // Counter at 0.8 USDC

// 3. Accept buyer's offer (triggers settlement)
await haggle.acceptOffer(negId);

Reading Negotiation State

const neg = await haggle.getNegotiation(negId);

console.log("Status:", neg.status);
console.log("Round:", neg.currentRound);
console.log("Current Offer:", ethers.formatUnits(neg.currentOfferAmount, 6), "USDC");
console.log("Effective Escrow:", ethers.formatUnits(neg.effectiveEscrow, 6), "USDC");

MCP Server Tools

When using the MCP server, these tools are available:

Key Parameters

Settlement Math

protocolFee    = settledAmount * 50 / 10000  (0.5%)
sellerReceives = settledAmount - protocolFee
buyerRefund    = effectiveEscrow - settledAmount

Negotiation Strategy Tips

1. Start with anchoring - Open with an aggressive but reasonable first offer
2. Concede gradually - Small concessions signal firmness
3. Watch the decay - Each round costs both parties
4. Monitor effectiveEscrow - As it decays, the viable offer range narrows

External Endpoints

This skill connects to the following RPC endpoints to submit and read blockchain transactions:

No data is sent to any other endpoints. No analytics, telemetry, or tracking of any kind.

Security & Privacy

• Local signing only - All transactions are signed locally using ethers.js. Your private key never leaves your machine.
• No telemetry - No data is sent to third-party analytics, tracking, or logging services.
• Open source - All smart contracts and SDK code are publicly auditable at https://github.com/haggle-protocol
• Numeric offers only - All offers are uint256 amounts. No free-text input, eliminating prompt injection risk.
• Contract-controlled escrow - Funds are held in on-chain contract vaults. No single party can rug pull.
• Turn-based enforcement - On-chain logic enforces alternating offers. Cannot submit out of turn.
• Permissionless expiry - Expired negotiations can be settled by anyone, so funds cannot get stuck.
• Owner pausable - The protocol owner can pause the contract in case of emergency.
• Not audited - The smart contracts have NOT been formally audited. Use at your own risk and start with small amounts.

Links

• Website: https://haggle.dev
• GitHub: https://github.com/haggle-protocol
• Base Dashboard: https://haggle.dev/base
• npm: https://www.npmjs.com/org/haggle-protocol
• BaseScan: https://basescan.org/address/0xB77B5E932de5e5c6Ad34CB4862E33CD634045514