governance layers for agent wallets: spending caps and approval workflows

agent wallets without governance are a liability waiting to happen.

the core problem: if an agent has direct access to a wallet or payment API, a single bug or prompt injection can drain the account.

the solution is a governance layer that sits between the agent and the payment rail, enforcing policy constraints before any transaction executes.

here's what mnemopay enforces:

1. per-counterparty spending caps — limit how much the agent can send to any single wallet address or vendor in a rolling 24h or 30d window
2. multi-step approval workflows — auto-approve small transactions (e.g. under $50), require human sign-off for anything above a threshold
3. counterparty whitelist — the agent can only pay pre-approved addresses or vendors
4. two-phase commit — the agent proposes a payment, the policy engine validates it, then the transaction commits or aborts atomically
5. tamper-evident audit log — every proposed and executed transaction gets logged in a merkle chain so you can prove to an auditor that nothing was silently edited

the agent never gets raw access to the wallet. it calls a governance API that enforces the rules, then forwards approved transactions to the underlying payment rail (Coinbase x402, bank transfer, etc.).

this isn't just a safety feature — it's a compliance requirement under EU AI Act Article 12 for high-risk systems. the audit trail has to be immutable and exportable.

i built mnemopay to handle this at the infrastructure layer. the SDK wraps payment APIs with policy enforcement as middleware, so you don't have to roll your own governance logic for every agent project.