WebSocketでのトークンアカウント（ATA）フィルタリング

const ws = new WebSocket('wss://mainnet.helius-rpc.com/?api-key=<API_KEY>');

ws.on('open', () => {
  ws.send(JSON.stringify({
    jsonrpc: '2.0',
    id: 1,
    method: 'transactionSubscribe',
    params: [
      {
        accountInclude: ['<WALLET_PUBKEY>'],
        tokenAccounts: 'balanceChanged' // also match the wallet's ATAs
      },
      { commitment: 'confirmed', encoding: 'jsonParsed', maxSupportedTransactionVersion: 0 }
    ]
  }));
  setInterval(() => ws.ping(), 30_000);
});

ws.on('message', (data) => {
  const msg = JSON.parse(data.toString());
  const result = msg.params?.result;
  if (!result) return;
  // Token balances this wallet owns that changed in the tx
  const owned = (result.transaction.meta.postTokenBalances || [])
    .filter((b) => b.owner === '<WALLET_PUBKEY>');
  console.log(result.signature, owned);
});