MsgAuthorization

The following code snippet requires LocalTerra.
test1 creates MsgGrantAuthorization message to grant MsgSend authorization to grantee test2.
test2 creates MsgExecAuthorized message to send 2000000000000uluna from the test1 account to the test3 account.
import {
  LCDClient,
  MnemonicKey,
  Wallet,
  MsgGrantAuthorization,
  SendAuthorization,
  MsgSend,
  Int,
  MsgExecAuthorized,
  Coins,
} from '@terra-money/feather.js';
function grant(
  granter: Wallet,
  grantee: string,
  spendLimit: Coins.Input,
  duration: Int,
) {
  const msgs = [
    new MsgGrantAuthorization(
      granter.key.accAddress('terra'),
      grantee,
      new SendAuthorization(spendLimit),
      duration,
    ),
  ];
  return granter.createAndSignTx({ msgs, chainID: 'pisco-1' });
}
function sendAuthorized(
  granter: Wallet,
  grantee: Wallet,
  to: string,
  amount: Coins.Input,
) {
  const msgs = [
    new MsgExecAuthorized(grantee.key.accAddress, [
      new MsgSend(
        granter.key.accAddress('terra'), // From test1
        to,
        amount,
      ),
    ]),
  ];
  return grantee.createAndSignTx({ msgs, chainID: 'pisco-1' });
}
async function main() {
  const client = new LCDClient(...);
  // Granter (terra1x46rqay4d3cssq8gxxvqz8xt6nwlz4td20k38v)
  const granter = client.wallet(
    new MnemonicKey({
      mnemonic:
        'notice oak worry limit wrap speak medal online prefer cluster roof addict wrist behave treat actual wasp year salad speed social layer crew genius',
    }),
  );
  // Grantee (terra17lmam6zguazs5q5u6z5mmx76uj63gldnse2pdp)
  const grantee = client.wallet(
    new MnemonicKey({
      mnemonic:
        'quality vacuum heart guard buzz spike sight swarm shove special gym robust assume sudden deposit grid alcohol choice devote leader tilt noodle tide penalty',
    }),
  );
  // MsgGrantAuthorization
  await grant(
    granter,
    grantee.key.accAddress('terra'),
    // Set enough spend limit since it will be decreased upon every MsgSend transactions
    '1000000000000uluna',
    // expire after 100 years
    new Int(86400 * 365 * 100 * 1000000000),
  )
    .then((tx) => client.tx.broadcast(tx, 'pisco-1'))
    .then(console.info)
    .catch((err) => {
      if (err.response) {
        console.error(err.response.data);
      } else {
        console.error(err.message);
      }
    });
  // MsgExecAuthorized of MsgSend
  await sendAuthorized(
    granter,
    grantee,
    // Test3
    'terra1757tkx08n0cqrw7p86ny9lnxsqeth0wgp0em95',
    '2000000000000uluna',
  )
    .then((tx) => client.tx.broadcast(tx, 'piscp-1'))
    .then(console.info)
    .catch((err) => {
      if (err.response) {
        // unauthorized: authorization not found: failed to execute message; message index: 0: failed to simulate tx
        // happens when the granted amount of tokens is exceeded.
        // insufficient funds: insufficient account funds; ...
        // happens when granter does not have enough tokens
        console.error(err.response.data);
      } else {
        console.error(err.message);
      }
    });
}
main().catch(console.error);