Buyer-controlled x402 recipe

Build a Base address evidence pack

Validate an EVM address, read its point-in-time Base account state, then retrieve recent official Circle USDC transfers over a bounded block range. The results are public-chain evidence, not proof of identity, ownership, authorization, solvency, or compliance.

3separately authorized steps
$0.01maximum listed total · USDC
eip155:8453Base network
1
$0.002 USDC · separate authorization

EVM address inspection

Validate, normalize, and checksum the supplied EVM address offline.

POSThttps://apiacre.com/v1/crypto/address-inspect

Input template

{
  "address": "$walletAddress"
}
Use this result

Stop unless result.data.valid is true, and reject result.data.isZero when the zero address is not explicitly intended.

2
$0.003 USDC · separate authorization

Base account status

Read ETH balance, nonce, and contract-code evidence at one safe Base block.

POSThttps://apiacre.com/v1/crypto/base-account-status

Input template

{
  "address": "$step1.result.data.checksumAddress",
  "block_tag": "safe"
}
Use this result

Review the resolved block and account fields as a point-in-time status; empty bytecode does not establish control or permanent account type.

3
$0.005 USDC · separate authorization

Base USDC transfer history

Retrieve newest-first official Base USDC events over a bounded range.

POSThttps://apiacre.com/v1/crypto/base-usdc-transfers

Input template

{
  "address": "$step1.result.data.checksumAddress",
  "lookback_blocks": 2000,
  "direction": "any",
  "limit": 25,
  "block_tag": "safe"
}
Use this result

Treat result.data.transfers as bounded public event evidence only; the result is not complete history or proof of transfer purpose or authority.

You stay in control. Each step is an independent API call. Inspect its HTTP 402 challenge, authorize no more than the displayed price, verify the result, and continue only when the output is suitable. The listed total is not a bundle charge.