Feat: Kalshi REST client for markets and orderbook

lib/kalshi/rest.js

@@ -0,0 +1,65 @@
+import { signRequest, KALSHI_API_BASE } from './auth.js';
+
+async function kalshiFetch(method, path, body = null) {
+  const headers = signRequest(method, path);
+  const opts = { method, headers };
+  if (body) opts.body = JSON.stringify(body);
+
+  const res = await fetch(`${KALSHI_API_BASE}${path}`, opts);
+  if (!res.ok) {
+    const text = await res.text();
+    throw new Error(`Kalshi API ${method} ${path} → ${res.status}: ${text}`);
+  }
+  return res.json();
+}
+
+/**
+ * Get events for the BTC 15-min series.
+ * Returns the currently active event + its markets.
+ */
+export async function getActiveBTCEvent() {
+  const data = await kalshiFetch('GET', '/trade-api/v2/events?series_ticker=KXBTC15M&status=open&limit=1');
+  const event = data.events?.[0];
+  if (!event) return null;
+  return event;
+}
+
+/**
+ * Get markets for a specific event ticker.
+ */
+export async function getEventMarkets(eventTicker) {
+  const data = await kalshiFetch('GET', `/trade-api/v2/events/${eventTicker}`);
+  return data.event?.markets || [];
+}
+
+/**
+ * Get orderbook for a specific market ticker.
+ */
+export async function getOrderbook(ticker) {
+  const data = await kalshiFetch('GET', `/trade-api/v2/markets/${ticker}/orderbook`);
+  return data.orderbook || data;
+}
+
+/**
+ * Get single market details.
+ */
+export async function getMarket(ticker) {
+  const data = await kalshiFetch('GET', `/trade-api/v2/markets/${ticker}`);
+  return data.market || data;
+}
+
+/**
+ * Place a real order on Kalshi. NOT used in paper mode.
+ */
+export async function placeOrder(params) {
+  return kalshiFetch('POST', '/trade-api/v2/portfolio/orders', params);
+}
+
+/**
+ * Get wallet balance.
+ */
+export async function getBalance() {
+  return kalshiFetch('GET', '/trade-api/v2/portfolio/balance');
+}
+
+export { kalshiFetch };