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Never fulfill from client state. Validate confirmed transaction data and atomically claim its hash in persistent storage before you reserve inventory, issue credentials, or return a paid resource.

Demo

The demo above is mock only. If you want to see onchain demos on Vibenet, head to Base chain demos.

Verify a Raw Token Transfer

Backend
claimOnce must use a database uniqueness constraint and participate in the same durable workflow as fulfillment. A process-local Set cannot prevent replay across restarts or multiple workers.
Only the first request with the expected chain, token, sender, recipient, amount, and optional memo reaches fulfillment.

Verify Every Settlement Shape

Direct transfer, EIP-3009 capture, and transferFrom after a permit all emit the same ERC-20 Transfer event. That makes the settlement check rail-agnostic, but the order binding differs: Choose a confirmation depth that matches the value and reversibility of fulfillment. See transaction finality for Base’s confirmation stages.

See Also

Request a Payment

Accept an immediately settled USDC or B20 checkout.

Watch for Payments

Backfill and process confirmed token events.