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POST
/
x402
/
agent
/
transfer-ownership
Prepare ERC-8004 identity ownership transfer
curl --request POST \
  --url https://api.sandbox.brickken.com/x402/agent/transfer-ownership \
  --header 'Content-Type: application/json' \
  --header 'X-Payment: <api-key>' \
  --data '
{
  "chainId": "8453",
  "newOwner": "<string>",
  "executionMode": "client-signed",
  "signerAddress": "<string>",
  "gasLimit": "<string>",
  "nonce": 123,
  "privateRpcUrl": "<string>",
  "ownerEmail": "jsmith@example.com",
  "email": "jsmith@example.com",
  "agentUuid": "<string>",
  "agentId": "<string>"
}
'
{
  "transactions": {},
  "txId": "<string>",
  "info": {}
}
Prepares an unsigned ERC-721 safeTransferFrom that moves an ERC-8004 agent identity from Brickken custody to a wallet you control. This facade maps to agentTransferOwnership. By default Brickken is the on-chain owner of the agent identity in brickken-relayed mode. Call this method only when you explicitly want to take custody of the identity NFT yourself.

​
Authentication

Omit x-api-key. Prepare is free. On POST /send-transactions the API returns 402 Payment Required; sign the x402 payment locally and retry with X-PAYMENT. In brickken-relayed mode Brickken’s relayer (the current owner) signs and broadcasts the transfer once payment is verified.

​
Key Fields

ParameterRequiredDescription
chainIdYesTarget chain ID. Use 8453 for Base mainnet or 84532 for Base Sepolia. Decimal and hex values are accepted.
newOwnerYesWallet that will receive the ERC-8004 identity NFT. Must differ from the current owner.
agentUuid or agentIdUsuallyAgent identifier from registration or the on-chain agent ID. The agent must already be registered on-chain.
executionModeNobrickken-relayed (recommended) or client-signed.
signerAddressConditionalRequired in client-signed mode (must be the current owner). Omit in brickken-relayed mode.

​
Response

Returns a prepared unsigned transaction and txId. Submit it to POST /send-transactions and complete the x402 payment.
  • brickken-relayed: send { txId, transactions }; Brickken signs and broadcasts.
  • client-signed: sign the transaction locally as the current owner, then send { txId, signedTransactions }.
Ownership transfer is irreversible and is different from agentSetWallet, which only changes the operational wallet. After the identity leaves Brickken custody, Brickken’s relayer can no longer perform owner-only operations for that agent unless ownership is transferred back.

Authorizations

​
X-Payment
string
header
required

Base64-encoded x402 payment payload. Supported for x402-eligible agentic methods on /x402/... facades, /prepare-transactions, and eligible /send-transactions retries.

Body

application/json
​
chainId
string
default:8453
required

Target operation chain ID. Use 8453 on Base mainnet or 84532 on Base Sepolia.

Examples:

"8453"

"84532"

​
newOwner
string
required

Wallet that will receive the ERC-8004 identity NFT.

Pattern: ^0x[a-fA-F0-9]{40}$
​
executionMode
enum<string>
default:client-signed

Execution mode. Use brickken-relayed to let Brickken's relayer sign, pay gas, and broadcast (omit signerAddress). Use client-signed to sign the prepared transaction yourself.

Available options:
brickken-relayed,
client-signed
​
signerAddress
string

Wallet that signs the prepared blockchain transaction. Required only in client-signed mode; omit in brickken-relayed mode.

Pattern: ^0x[a-fA-F0-9]{40}$
​
gasLimit

Optional explicit gas limit.

​
nonce
number

Optional explicit nonce when managing nonces manually.

​
privateRpcUrl
string

Optional private RPC URL override.

​
ownerEmail
string<email>

Optional owner attribution email.

​
email
string<email>

Alias for ownerEmail where supported.

​
agentUuid
string

Stored tokenized agent UUID returned by agentRegister.

​
agentId
string

On-chain ERC-8004 agent ID.

Response

Prepared unsigned transaction payload.

​
transactions
object
​
txId
string
​
info
object