Knowing the Next Block Producer in Advance (Leader Schedule)

import { Connection, Transaction, sendAndConfirmTransaction } from "@solana/web3.js";

const conn = new Connection(process.env.RPC_URL);

// Get the upcoming leader schedule
const slot = await conn.getSlot();
const leaderSchedule = await conn.getLeaderSchedule(slot);
// Returns { <validatorPubkey>: [slot1, slot2, ...] }

// Get current + next 2 leaders' TPU addresses
const clusterNodes = await conn.getClusterNodes();
const upcomingLeaders = []; // logic to find next 3 leaders from leaderSchedule

// Get their tpuQuic / tpu socket addresses
const upcomingTpus = upcomingLeaders.map(l => {
  const node = clusterNodes.find(n => n.pubkey === l);
  return node?.tpuQuic ?? node?.tpu;
}).filter(Boolean);

// Send transaction via UDP to all upcoming leaders simultaneously
// (RPC providers like Helius/Triton do this for you internally)
const tx = new Transaction().add(...);
tx.recentBlockhash = (await conn.getLatestBlockhash()).blockhash;
tx.sign(wallet);
const serialized = tx.serialize();

await Promise.all(upcomingTpus.map(tpu => sendUdpTx(serialized, tpu)));

// Why send to multiple: if leader N misses their slot, leader N+1 sees your tx
// Standard pattern: send to current + next 2 leaders for redundancy