Orderbook Data

wss://api.bison.markets/ws/kalshi/orderbook/{marketTicker}

const marketTicker = "KXBTC-100K-DEC31";
const ws = new WebSocket(
  `wss://api.bison.markets/ws/kalshi/orderbook/${marketTicker}`
);

// Track orderbook state
let orderbook = {
  yes: new Map(), // price_uusdc -> ccontracts (bigint)
  no: new Map()   // price_uusdc -> ccontracts (bigint)
};

ws.onopen = () => {
  console.log(`Connected to ${marketTicker} orderbook`);
  
  // Send heartbeat every 30 seconds
  setInterval(() => {
    if (ws.readyState === WebSocket.OPEN) {
      ws.send(JSON.stringify({ type: "ping" }));
    }
  }, 30000);
};

ws.onmessage = (event) => {
  const data = JSON.parse(event.data);
  
  if (data.type === "orderbook_snapshot") {
    handleSnapshot(data);
  } else if (data.type === "orderbook_delta") {
    handleDelta(data);
  }
};

function handleSnapshot(snapshot) {
  // Reset orderbook with full snapshot
  orderbook.yes.clear();
  orderbook.no.clear();
  
  if (snapshot.yes) {
    snapshot.yes.forEach(level => {
      orderbook.yes.set(level.price_uusdc, BigInt(level.ccontracts));
    });
  }
  
  if (snapshot.no) {
    snapshot.no.forEach(level => {
      orderbook.no.set(level.price_uusdc, BigInt(level.ccontracts));
    });
  }
  
  console.log("Orderbook initialized:", orderbook);
}

function handleDelta(delta) {
  // Apply incremental update
  const book = delta.side === "yes" ? orderbook.yes : orderbook.no;
  const currentCcontracts = book.get(delta.price_uusdc) || 0n;
  const newCcontracts = currentCcontracts + BigInt(delta.delta);
  
  if (newCcontracts <= 0n) {
    book.delete(delta.price_uusdc);
  } else {
    book.set(delta.price_uusdc, newCcontracts);
  }
  
  console.log(`Orderbook updated: ${delta.side} @ ${delta.price_uusdc}: ${newCcontracts.toString()}`);
}

{
  "type": "orderbook_snapshot",
  "market_ticker": "KXBTC-100K-DEC31",
  "yes": [
    { "price_uusdc": "750000", "ccontracts": "100" },
    { "price_uusdc": "740000", "ccontracts": "250" },
    { "price_uusdc": "730000", "ccontracts": "500" }
  ],
  "no": [
    { "price_uusdc": "260000", "ccontracts": "150" },
    { "price_uusdc": "270000", "ccontracts": "300" },
    { "price_uusdc": "280000", "ccontracts": "400" }
  ]
}

{
  "type": "orderbook_delta",
  "market_ticker": "KXBTC-100K-DEC31",
  "side": "yes",
  "price_uusdc": "750000",
  "delta": "50"
}

class OrderbookManager {
  constructor(marketTicker) {
    this.marketTicker = marketTicker;
    this.orderbook = {
      yes: new Map(),
      no: new Map()
    };
    this.ws = null;
  }
  
  connect() {
    this.ws = new WebSocket(
      `wss://api.bison.markets/ws/kalshi/orderbook/${this.marketTicker}`
    );
    
    this.ws.onmessage = (event) => {
      const data = JSON.parse(event.data);
      
      if (data.type === "orderbook_snapshot") {
        this.applySnapshot(data);
      } else if (data.type === "orderbook_delta") {
        this.applyDelta(data);
      }
    };
    
    // Heartbeat
    setInterval(() => {
      if (this.ws.readyState === WebSocket.OPEN) {
        this.ws.send(JSON.stringify({ type: "ping" }));
      }
    }, 30000);
  }
  
  applySnapshot(snapshot) {
    this.orderbook.yes.clear();
    this.orderbook.no.clear();
    
    if (snapshot.yes) {
      snapshot.yes.forEach(level => {
        this.orderbook.yes.set(level.price_uusdc, BigInt(level.ccontracts));
      });
    }
    
    if (snapshot.no) {
      snapshot.no.forEach(level => {
        this.orderbook.no.set(level.price_uusdc, BigInt(level.ccontracts));
      });
    }
    
    this.render();
  }
  
  applyDelta(delta) {
    const book = delta.side === "yes" ? this.orderbook.yes : this.orderbook.no;
    const currentCcontracts = book.get(delta.price_uusdc) || 0n;
    const newCcontracts = currentCcontracts + BigInt(delta.delta);
    
    if (newCcontracts <= 0n) {
      book.delete(delta.price_uusdc);
    } else {
      book.set(delta.price_uusdc, newCcontracts);
    }
    
    this.render();
  }
  
  render() {
    console.log(`\n=== ${this.marketTicker} Orderbook ===`);
    
    // YES side (sorted descending by price)
    console.log("\nYES:");
    const yesPrices = Array.from(this.orderbook.yes.keys()).sort((a, b) => Number(b) - Number(a));
    yesPrices.forEach(price => {
      const ccontracts = this.orderbook.yes.get(price) || 0n;
      const priceUSDC = (Number(price) / 1_000_000).toFixed(2);
      console.log(`  ${priceUSDC}: ${ccontracts.toString()} ccontracts`);
    });
    
    // NO side (sorted descending by price)
    console.log("\nNO:");
    const noPrices = Array.from(this.orderbook.no.keys()).sort((a, b) => Number(b) - Number(a));
    noPrices.forEach(price => {
      const ccontracts = this.orderbook.no.get(price) || 0n;
      const priceUSDC = (Number(price) / 1_000_000).toFixed(2);
      console.log(`  ${priceUSDC}: ${ccontracts.toString()} ccontracts`);
    });
  }
  
  getBestBidAsk() {
    const yesPrices = Array.from(this.orderbook.yes.keys()).map(Number);
    const noPrices = Array.from(this.orderbook.no.keys()).map(Number);
    
    return {
      yesBid: yesPrices.length > 0 ? Math.max(...yesPrices) : null,
      yesAsk: yesPrices.length > 0 ? Math.min(...yesPrices) : null,
      noBid: noPrices.length > 0 ? Math.max(...noPrices) : null,
      noAsk: noPrices.length > 0 ? Math.min(...noPrices) : null,
    };
  }
  
  disconnect() {
    if (this.ws) {
      this.ws.close();
    }
  }
}

// Usage
const manager = new OrderbookManager("KXBTC-100K-DEC31");
manager.connect();

// Later, get best bid/ask
const { yesBid, yesAsk, noBid, noAsk } = manager.getBestBidAsk();
console.log(`Best YES: ${yesBid} / ${yesAsk}`);
console.log(`Best NO: ${noBid} / ${noAsk}`);