Build Create-Account Payload

// Replace `<action>` with the action of THIS page (e.g. create-account, deposit, …)
const endpoint = 'api/2/perp/payloads/<action>';
const timestamp = Date.now();
const signature = await wallet.signMessage(`${endpoint}-${timestamp}`);

await fetch(`https://api.mobula.io/${endpoint}`, {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    timestamp,
    signature,
    // ...action-specific fields below
  }),
});

// 1. Auth-sign + fetch the create-account payload
const endpoint = 'api/2/perp/payloads/create-account';
const ts = Date.now();
const authSig = await wallet.signMessage(`${endpoint}-${ts}`);

const { data } = await fetch(`https://api.mobula.io/${endpoint}`, {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    timestamp: ts,
    signature: authSig,
    dex: 'lighter',
    chainId: 'lighter:304',
    accountIndex,         // discovered from Lighter's /api/v1/account lookup
    apiKeyIndex: 100,     // any unused slot
  }),
}).then(r => r.json());

// 2. Mutate the envelope only if Lighter returns an L1 challenge
const parsed = JSON.parse(data.payloadStr);
let finalPayloadStr = data.payloadStr;

if (parsed.payload.MessageToSign) {
  parsed.payload.L1Sig = await wallet.signMessage(parsed.payload.MessageToSign);
  delete parsed.payload.MessageToSign;
  finalPayloadStr = JSON.stringify(parsed);
}

// 3. Sign + submit execute-v2
const execTs = Date.now();
const execSig = await wallet.signMessage(
  `api/2/perp/execute-v2-${execTs}-${finalPayloadStr}`,
);

const execRes = await fetch('https://api.mobula.io/api/2/perp/execute-v2', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    action: data.action,
    dex: data.dex,
    chainId: data.chainId,
    transport: data.transport,
    payloadStr: finalPayloadStr,
    timestamp: execTs,
    signature: execSig,
  }),
}).then(r => r.json());

async function pollLighterAccountIndex(eoaAddress, { intervalMs = 1000, maxRetries = 200 } = {}) {
  for (let i = 0; i < maxRetries; i++) {
    const res = await fetch(
      `https://mainnet.zklighter.elliot.ai/api/v1/account?by=l1_address&value=${eoaAddress}`,
      { headers: { Accept: 'application/json' } },
    ).then(r => r.json()).catch(() => null);

    if (res?.code === 200 && res.accounts?.[0]?.account_index != null) {
      return res.accounts[0].account_index;
    }
    await new Promise(r => setTimeout(r, intervalMs));
  }
  throw new Error(`Lighter accountIndex not found for ${eoaAddress} after ${maxRetries} polls`);
}