Adding your own fee

import { type WalletClient } from 'viem';

const API = 'https://app.dynamicauth.com/api/v0';
const ENV_ID = 'your-environment-id';
const API_TOKEN = 'dyn_your_api_token'; // must have flow.write scope

// The recipient wallet from feeConfig — it signs to authorize the claim.
declare const wallet: WalletClient;

const claimFees = async (recipientAddress: `0x${string}`) => {
  const headers = {
    Authorization: `Bearer ${API_TOKEN}`,
    'Content-Type': 'application/json',
  };

  // 1. Is there anything to claim?
  const balancesRes = await fetch(
    `${API}/server/${ENV_ID}/flow/fees/balances?recipientAddress=${recipientAddress}`,
    { headers },
  );
  const { hasClaimableFees } = await balancesRes.json();
  if (!hasClaimableFees) {
    return;
  }

  // 2. Initiate — get the steps to sign.
  const initRes = await fetch(`${API}/server/${ENV_ID}/flow/fees/claim`, {
    body: JSON.stringify({ recipientAddress }),
    headers,
    method: 'POST',
  });
  const { requestId, steps } = await initRes.json();

  // 3. Sign each step's message with the recipient wallet.
  // data.signatureKind is `eip191` — viem's signMessage produces exactly that.
  const signatures = await Promise.all(
    steps.map(async (step: { data: { message: string }; id: string }) => ({
      signature: await wallet.signMessage({
        account: recipientAddress,
        message: step.data.message,
      }),
      stepId: step.id,
    })),
  );

  // 4. Submit the signatures.
  const submitRes = await fetch(
    `${API}/server/${ENV_ID}/flow/fees/claim/submit`,
    {
      body: JSON.stringify({ requestId, signatures }),
      headers,
      method: 'POST',
    },
  );

  return submitRes.json();
};