An AI assistant can help you make payments, but it needs a way to execute transactions without having access to your wallet's private key.
In this build, we'll explore how to delegate USDT0 payments to an AI assistant on Stable. Using an ERC-20 allowance, you can authorize the assistant's signer to spend up to a specified amount while keeping control of your wallet in MetaMask.
We’ll use a demo on Stable Testnet and @stablechain/agent-wallet-clito follow a payment from approval to confirmation and revocation. The page prepares prompts; the CLI runs in your assistant’s environment, signs transferFrom transactions and persists signed transactions for recovery. Payments and gas both use USDT0.
Suppose Alice covered dinner. You owe her 6 USDT0. You tell your assistant:
“Send Alice 6 USDT0. Here’s her wallet address.”
Let's see how the assistant can execute that payment within the spending limit you've approved.
You approve 10 USDT0 for the agent’s signer:
// Signed by you. ERC-20 USDT0 uses 6 decimals.
USDT0.approve(agent, 10_000_000);
The token contract records allowance(owner, agent). That allowance permits aggregate spending up to 10 USDT0, to any recipient. It has no expiry and reserves no funds.
The allowance does not encode Alice, dinner or “once.” Your instruction authorizes one payment; the signer holds broader authority. Recipient restrictions and expiry require a different authorization design.
Once the approval is confirmed, the agent signs a transaction calling the USDT0 contract:
// Signed by the agent.
USDT0.transferFrom(owner, aliceAddress, 6_000_000);
The contract checks your balance and the agent’s allowance. A successful transfer moves 6 USDT0 from your account to Alice’s and reduces the allowance to 4, assuming no other spending or changes.
The agent pays gas from its own account. On Stable, USDT0 is also the native gas asset: its native interface uses 18 decimals; its ERC-20 interface uses 6. Both expose the same underlying balance per account.
Fund the signer for gas before sending. Those fees sit outside your token allowance.
A transaction hash gives you something to look up. Confirmation requires a successful receipt with evidence of the requested transfer.
The CLI verifies the transaction’s signer, token contract, and calldata, and matches a USDT0 Transfer event from your address to Alice’s for the exact amount. It reports confirmed only after those checks pass.
The transaction may be confirmed while your client is still waiting for a response. Alice may already have received the funds.
The CLI persists the signed transaction and nonce before broadcasting. Keep the original payment ID and signer directory to check or recover that transaction. Recovery can reuse the saved signed bytes.
Starting over with a new ID creates a separate payment intent. The ID is local bookkeeping, not an onchain duplicate check. If two payments fit within the allowance, the contract permits both.
Once Alice’s payment is confirmed, sign approve(agent, 0) from your wallet and wait for confirmation. Further payments using that allowance then fail. Revocation doesn’t undo confirmed transfers or reclaim the signer’s gas balance.
The demo runs this flow on Stable Testnet with smaller amounts. Use a second testnet wallet for Alice: approve 0.01 USDT0, send 0.006, then dry-run another 0.006. The CLI rejects it before signing because only 0.004 allowance remains. Revoke the remainder and check that another payment fails.
Source and setup · CLI and recovery reference
Testnet only; unaudited. Signer keys are plaintext files with restricted permissions. Keep the state private and persistent.
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