Migrate from Zerion API to GoldRush

// BEFORE -- Zerion: Basic auth, JSON:API envelope, all chains by default
const auth = Buffer.from(process.env.ZERION_API_KEY + ":").toString("base64");
const res = await fetch(
  "https://api.zerion.io/v1/wallets/" + address +
    "/positions/?currency=usd&filter[positions]=only_simple",
  { headers: { accept: "application/json", authorization: "Basic " + auth } }
);
const { data } = await res.json();

// Amounts live under attributes; chain under relationships.
const tokens = data.map((p) => ({
  symbol: p.attributes.fungible_info.symbol,
  amount: p.attributes.quantity.float,
  usd: p.attributes.value,
  chain: p.relationships.chain.data.id,
}));

// AFTER -- GoldRush: Bearer auth, flat items[], one chain per path
const res = await fetch(
  "https://api.covalenthq.com/v1/eth-mainnet/address/" + address + "/balances_v2/",
  { headers: { Authorization: "Bearer " + process.env.GOLDRUSH_API_KEY } }
);
const { data, error, error_message } = await res.json();
if (error) throw new Error(error_message);

// balance is the raw integer string; divide by contract_decimals yourself.
const tokens = data.items.map((t) => ({
  symbol: t.contract_ticker_symbol,
  amount: Number(t.balance) / 10 ** t.contract_decimals,
  usd: t.quote,
  chain: data.chain_name,
}));

// BEFORE -- Zerion returns every chain by default; narrow with a filter.
const res = await fetch(
  "https://api.zerion.io/v1/wallets/" + address +
    "/positions/?filter[chain_ids]=ethereum,base,arbitrum",
  { headers: { authorization: "Basic " + auth } }
);

// AFTER -- GoldRush uses a dedicated allchains endpoint.
const res = await fetch(
  "https://api.covalenthq.com/v1/allchains/address/" + address +
    "/balances/?chains=eth-mainnet,base-mainnet,arbitrum-mainnet",
  { headers: { Authorization: "Bearer " + process.env.GOLDRUSH_API_KEY } }
);
const { data } = await res.json();

// BEFORE -- Zerion hands you the next URL; follow it until it is absent.
let url =
  "https://api.zerion.io/v1/wallets/" + address + "/transactions/?page[size]=100";
const all = [];
while (url) {
  const res = await fetch(url, { headers: { authorization: "Basic " + auth } });
  const body = await res.json();
  all.push(...body.data);
  url = body.links?.next;
}

// AFTER -- GoldRush pages by number in the path.
// NOTE: page 0 is the OLDEST page. Walk down from has_more, or start at 0
// and ascend if you want chronological order.
const all = [];
let page = 0;
for (;;) {
  const res = await fetch(
    "https://api.covalenthq.com/v1/eth-mainnet/address/" + address +
      "/transactions_v3/page/" + page + "/",
    { headers: { Authorization: "Bearer " + process.env.GOLDRUSH_API_KEY } }
  );
  const { data, error, error_message } = await res.json();
  if (error) throw new Error(error_message);
  all.push(...data.items);
  if (!data.links?.next) break;
  page += 1;
}

# BEFORE -- Zerion requires a dashboard account and a provisioned key
# before an agent can make its first call.
curl -H "Authorization: Basic $(printf '%s:' "$ZERION_API_KEY" | base64)" \
  "https://api.zerion.io/v1/wallets/$ADDRESS/positions/"

# AFTER -- GoldRush x402: the agent pays from its own wallet.
# No signup, no dashboard, no long-lived credential to rotate.
curl "https://api.covalenthq.com/v1/eth-mainnet/address/$ADDRESS/balances_v2/"
# -> 402 Payment Required, with payment details in the response.
# An x402-aware client settles onchain and retries automatically.