Market Making Agent

This guide shows how a market maker listens for auction requests and provides signed bids.

Maker (liquidity provider) flow

1. Connect to the WebSocket
2. Listen for auction.started { auctionId, maker, wager, resolver, predictedOutcomes[] }
3. Construct and send bid.submit { auctionId, taker, takerWager, takerDeadline, takerSignature, makerNonce }
4. Receive bid.ack { error? }
5. Optionally auction.subscribe { auctionId } to keep receiving auction.bids

Minimal listener and bid (Node)

import WebSocket from 'ws';
 
const ws = new WebSocket('wss://api.sapience.xyz/auction');
 
ws.on('message', (data) => {
  try {
    const msg = JSON.parse(String(data));
    if (msg.type === 'auction.started') {
      const auction = msg.payload;
      const bid = createBid(auction);
      ws.send(JSON.stringify(bid));
    }
  } catch (e) {
    console.error('parse error', e);
  }
});
 
function createBid(auction: any) {
  const now = Math.floor(Date.now() / 1000);
  return {
    type: 'bid.submit',
    payload: {
      auctionId: auction.auctionId,
      taker: '0xMakerEOAUsedToProvideLiquidity...',
      takerWager: (BigInt(auction.wager) / 2n).toString(),
      takerDeadline: now + 60,
      takerSignature: '0x' + '11'.repeat(32) + '22'.repeat(32),
      makerNonce: 1,
    },
  } as const;
}

Notes

• Ensure ERC‑20 approvals for the collateral token if you automate on-chain fills
• The relayer enforces structure and expiry; optional strict EIP‑712 verification mirrors on‑chain SignatureProcessor

Reference

• Builder Reference: [Auction Relayer](/builder-guide/reference/auction-relayer)
• On-chain: packages/protocol/src/predictionMarket/PredictionMarket.sol