Comparing Venue Prices

The same prediction market often trades on more than one venue at the same time, at different prices. sufwan-local-test's matching pipeline links those markets together as matchedVenueMarkets so you can build a cross-venue price comparison in three calls:

1. List matched events — events confirmed on two or more venues.
2. Walk every market and its matched siblings — collect each venueMarketId.
3. Batch-fetch midpoints — one getMidpoints call returns the live Yes-side price per market. The client batches 75 ids.

The midpoint is the live orderbook's headline mark on a 0–1 scale, where 0.55 means the market implies a 55% probability of "Yes". Comparing midpoints across venues for the same matched event surfaces the spread an arbitrageur, smart router, or "best price" badge cares about.

1. Create the clientCopy Anchor Link

import { createAggClient, MarketStatus, MatchStatus } from "@agg-build/sdk";

const client = createAggClient({
  baseUrl: "https://api.t.sufwankhalid.com",
  appId: "your-app-id",
});

2. List matched eventsCopy Anchor Link

getVenueEvents accepts matchStatus as an array. Pass ["matched", "verified"] to restrict the response to events confirmed across more than one venue — every market in the response includes its matchedVenueMarkets. Calls GET /venue-events.

const { data: events } = await client.getVenueEvents({
  status: [MarketStatus.open],
  matchStatus: [MatchStatus.matched, MatchStatus.verified],
  limit: 50,
});

3. Collect every venueMarketIdCopy Anchor Link

Walk the response and gather every market ID — the event's own markets plus each matchedVenueMarkets[].id.

const ids = new Set<string>();
for (const event of events) {
  for (const market of event.venueMarkets ?? []) {
    ids.add(market.id);
    for (const matched of market.matchedVenueMarkets ?? []) {
      ids.add(matched.id);
    }
  }
}

The venueMarkets array on a list event is a preview of up to three markets. Page GET /venue-markets?venueEventId= for the full set. Sibling venues stay on matchedVenueMarkets[]. Which id to pass is Ids. Midpoints take venueMarketId.

4. Batch-fetch midpointsCopy Anchor Link

The client sends at most 75 ids per request and merges the responses. Pass bestPrice=true to add bestBid, bestAsk, and arbReturn. Two Hyperliquid listings in one cluster are different books. See Hyperliquid deployers.

const { data: midpoints } = await client.getMidpoints({
  venueMarketIds: [...ids],
  bestPrice: true,
});

Get live midpoints for multiple markets.

Entries are never dropped — check error before trusting a priceCopy Anchor Link

Every requested id gets an entry back, even one the API can't price. Unknown or resolved markets return midpoint: null alongside a structured error rather than being omitted, so the response array stays aligned with the ids you sent and a batched request can't silently shift. GET /orderbooks behaves the same way.

for (const m of midpoints) {
  if (m.error) {
    console.warn(`skipping ${m.venueMarketId}: ${m.error.code}`);
    continue;
  }
  // m.midpoint may still be null when the book is empty but the market is live.
}

5. Build the comparisonCopy Anchor Link

Index midpoints by venueMarketId, then for each market look up its own midpoint plus its siblings'.

const byId = new Map(midpoints.map((m) => [m.venueMarketId, m]));

for (const event of events) {
  for (const market of event.venueMarkets ?? []) {
    const own = byId.get(market.id);
    const siblings = (market.matchedVenueMarkets ?? [])
      .map((m) => byId.get(m.id))
      .filter((m): m is NonNullable<typeof m> => !!m);

    const usable = [own, ...siblings].filter(
      (m): m is NonNullable<typeof m> => !!m && m.midpoint !== null,
    );
    if (usable.length < 2) continue;

    const cheapest = usable.reduce((a, b) => (a.midpoint! < b.midpoint! ? a : b));
    const richest = usable.reduce((a, b) => (a.midpoint! > b.midpoint! ? a : b));

    console.log(event.id, {
      spread: richest.midpoint! - cheapest.midpoint!,
      cheapest: { venue: cheapest.venue, midpoint: cheapest.midpoint },
      richest: { venue: richest.venue, midpoint: richest.midpoint },
    });
  }
}

Live updatesCopy Anchor Link

/midpoints is a snapshot. There is no midpoint WebSocket channel. Live depth is the orderbook socket, keyed by venueMarketOutcomeId. Snapshots and deltas on that socket include a midpoint for the outcome.

RelatedCopy Anchor Link