Agent wallets: when the software holds the keys
AI agents that transact onchain need wallets, and giving an autonomous program unrestricted keys is an obviously bad idea. This note surveys how smart accounts turn "the agent has my money" into "the agent has a budget."
A conventional wallet is binary: whoever holds the private key can do anything. Smart accounts — the account-abstraction model standardized as ERC-4337 — replace that key with programmable logic, and that single change is what makes agent custody tractable.
The useful primitive is the session key: a temporary credential scoped to specific contracts, specific functions, a spending cap, and an expiry. An agent buying compute or paying for API calls can be granted exactly that ability and nothing else. If the agent is compromised or simply wrong, the blast radius is the budget, not the account.
What to evaluate in any agent system
Three questions sort serious designs from demos. Who can revoke the agent's permissions, and how fast? Is the spending policy enforced onchain, where the agent cannot route around it, or merely in the agent's own code? And is there an activity log a human actually reviews? On Base, where each transaction costs fractions of a cent, the honest answer to the last question is observable: the agent's full history is public, whether or not anyone is reading it.