LaserStreamヒストリカルリプレイ：欠落データのバックフィル

async function getCurrentSlot(): Promise<number> {
  const r = await fetch(`https://mainnet.helius-rpc.com/?api-key=${process.env.HELIUS_API_KEY}`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ jsonrpc: '2.0', id: 1, method: 'getSlot', params: [{ commitment: 'confirmed' }] }),
  });
  const { result } = await r.json();
  return result as number;
}

// Load the last slot you processed from wherever you store it.
let lastProcessedSlot = Number(process.env.LAST_PROCESSED_SLOT ?? 0);

// Check if it's still within the replay window
// (~691,200 slots at current ~250ms slot time; recompute if network slot time changes)
const currentSlot = await getCurrentSlot();
const maxReplaySlot = currentSlot - 691_200;

if (lastProcessedSlot < maxReplaySlot) {
  console.warn('Disconnection too long, some data may be lost');
  lastProcessedSlot = maxReplaySlot;
}

const subscriptionRequest: SubscribeRequest = {
  // ... your subscription config
  fromSlot: lastProcessedSlot, // pass as number, not string
};

await subscribe(config, subscriptionRequest,
  async (data) => {
    // your handler here
    if (data.transaction?.slot) {
      lastProcessedSlot = Number(data.transaction.slot);
      // persist `lastProcessedSlot` here so the next reconnect picks up
    }
  }
);

// Get a slot from 10 minutes ago (within the 48-hour window)
const currentSlot = await getCurrentSlot();
const startSlot = currentSlot - 2400; // ~10 minutes ago at current ~250ms slot time

const subscriptionRequest: SubscribeRequest = {
  // ... your subscription config
  fromSlot: startSlot, // u64 number
};

// Test with data from the last 5 minutes
const currentSlot = await getCurrentSlot();
const testStartSlot = currentSlot - 1200; // ~5 minutes ago at current ~250ms slot time
const testEndSlot = currentSlot - 240;    // ~1 minute ago at current ~250ms slot time

const subscriptionRequest: SubscribeRequest = {
  // ... your subscription config
  fromSlot: testStartSlot, // u64 number
};

// Stop processing when reaching the test end slot
const stream = await subscribe(config, subscriptionRequest,
  async (data) => {
    const slot = Number(data.transaction?.slot ?? data.account?.slot ?? 0);
    if (slot >= testEndSlot) {
      stream.cancel();
      return;
    }
    // your test handler here
  }
);