Detect Liquidity Drains in Real Time

// drain-detector.mjs: alert when a pool loses a big share of its liquidity
// in one block. Node 18+, no dependencies, no API key.

const POOLS = [
  { chain: "ethereum", address: "0x88e6a0c2ddd26feeb64f039a2c41296fcb3f5640", label: "USDC/WETH 0.05%" },
  { chain: "base", address: "0xb2cc224c1c9fee385f8ad6a55b4d94e92359dc59", label: "WETH/USDC (Aerodrome)" },
  { chain: "solana", address: "8sjV1AqBFvFuADBCQHhotaRq5DFFYSjjg1jMyVWMqXvZ", label: "USDT/USDC (Orca)" },
];

const MIN_USD = 10_000; // ignore moves smaller than this
const MIN_PCT = 0.2; // ...and smaller than this share of the pool

async function watch() {
  const res = await fetch("https://streaming.dexpaprika.com/sse/reserves", {
    method: "POST",
    headers: { "content-type": "application/json" },
    body: JSON.stringify(POOLS.map(({ chain, address }) => ({ chain, address, method: "pool_reserves" }))),
  });
  if (!res.ok) throw new Error(`${res.status}: ${await res.text()}`);

  let buffer = "";
  for await (const chunk of res.body.pipeThrough(new TextDecoderStream())) {
    buffer += chunk;
    const frames = buffer.split("\n\n");
    buffer = frames.pop(); // keep the partial frame for the next chunk

    for (const frame of frames) {
      const event = frame.match(/^event: (.*)$/m)?.[1];
      const id = frame.match(/^request_id: (.*)$/m)?.[1];
      const data = frame.match(/^data: (.*)$/m)?.[1];
      if (!data) continue;
      if (event === "error") throw new Error(JSON.parse(data).message);
      if (event !== "pool_reserves") continue; // skip pings and warnings

      const update = JSON.parse(data);
      const delta = update.total_delta_usd;
      const before = update.total_reserve_usd - delta; // reserve before this block
      const pct = before > 0 ? delta / before : 0;

      // A swap moves one token up and the other down, so total_delta_usd nets
      // to ~0. Only liquidity entering or leaving the pool moves the total.
      if (Math.abs(delta) < MIN_USD || Math.abs(pct) < MIN_PCT) continue;

      const pool = POOLS[Number(id)] ?? { label: update.pool_id };
      const verb = delta < 0 ? "🚨 DRAIN" : "🟢 ADD";
      console.log(
        `${verb} ${pool.label} on ${update.chain}: ` +
          `${delta < 0 ? "-" : "+"}$${Math.abs(delta).toLocaleString("en-US", { maximumFractionDigits: 0 })} ` +
          `(${(pct * 100).toFixed(1)}% of the pool) at block ${update.block}`,
      );
    }
  }
}

while (true) {
  try {
    console.log("connecting…");
    await watch();
  } catch (err) {
    console.error(String(err));
  }
  await new Promise((r) => setTimeout(r, 5000)); // simple retry; see the production guide
}