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INFRASTRUCTURE · PRODUCT BRIEF
Base x402 Agent Payments
Research a safe path for AI agents to understand and pay for USDC-priced APIs.
Base x402 Agent Payments is an R&D product where an API presents price and payment conditions through a 402 challenge, an agent creates a bounded payment authorization, and the server validates request fingerprint, nonce and policy. Only mock E2E and Base Sepolia readiness are verified; funded wallet settlement, facilitator operations and Mainnet payment are not.
x402 v2EIP-3009Base SepoliaUSDCSDK
SAMPLE UI · NO LIVE TRANSACTION
LOCAL R&D PROTOCOL
HTTP 402From 402 to a verified response
GET
/v1/agent/data40201PAYMENT-REQUIRED
02EIP-3009 · STRUCTURAL
03Replay · protected
04Settlement · MOCK
payment-required → authorize → verify
All hashes and settlement results are samples, not onchain transactions.
Intended outcome
A verifiable protocol flow connecting payment requirements, bounded authorization, API response and replay protection
PRODUCT FLOW
Four steps users can understand
01 · API request
The agent calls a protected, priced API.
02 · 402 challenge
The server returns exact asset, amount, network and expiry conditions.
03 · Bounded authorization
The agent wallet prepares an EIP-3009 authorization bound to the request.
04 · Verify then respond
The gateway returns the API result only after policy and replay checks.
INTERFACE TEMPLATE
Sample product interface
A code-native sample for reviewing the product structure without real keys, transactions or customer data.SAMPLE UI · NO LIVE TRANSACTION
LOCAL R&D PROTOCOL
HTTP 402From 402 to a verified response
GET
/v1/agent/data40201PAYMENT-REQUIRED
02EIP-3009 · STRUCTURAL
03Replay · protected
04Settlement · MOCK
payment-required → authorize → verify
All hashes and settlement results are samples, not onchain transactions.
CAPABILITIES
Designed capabilities
x402 v2 header flow
Models PAYMENT-REQUIRED, PAYMENT-SIGNATURE and PAYMENT-RESPONSE boundaries.
Request fingerprint
Price, route and server request ID are bound to the payment identifier.
Replay protection
Exact retries are idempotent while conflicting nonce reuse is rejected.
Gateway and SDK
Provides a typed client boundary for server and agent integration.
Mock Playground
Explores states from 402 to mock settlement without real assets.
INTEGRATION SEQUENCE
Implementation sequence
- Define resource priceAttach fixed asset, amount and network policy to the API route.
- 402 middlewareUnpaid requests receive only a normalized challenge.
- Agent clientThe client validates the challenge and creates a bounded authorization.
- Verification and settlement adapterToday this is deterministic mock; a live adapter requires separate approval.
SERVER-SIDE PSEUDOCODE · NO CREDENTIALS
Server integration sketch
Secrets never enter the browser. Every external response is verified by the server before product state advances.
const challenge = await agent.fetch(resourceUrl); // HTTP 402
const payment = await policy.authorize(challenge);
const response = await agent.retry({ payment });
await verifier.record(response.receipt);SECURITY
Security and responsibility
Non-custodial
The gateway accepts no wallet private key or seed.
Strict schemas
Challenge and authorization fields, chain, token, amount and expiry are validated.
Policy first
Unauthorized requests do not learn prior nonce-conflict state.
Explicit mock labeling
A mock identifier is never presented as a transaction hash or live settlement.
READINESS
Current limitations
Local R&D
There is no public production gateway or customer SLA.
Funded settlement unverified
No funded-wallet and facilitator settlement has been run end to end.
Mainnet unverified
No Base Mainnet payment or production provider is claimed.
Commercial review required
Billing, support, abuse, legal and independent security review remain required.
Market and operating boundary