Agent Identity and Reputation

Brain uses ERC-8004 as the foundation for agent identity and trust, providing persistent, chain-agnostic identifiers and composable reputation that travels with the agent across platforms.

Why Portable Identity Matters

Without a standard for agent identity, trust is siloed. An agent with a perfect performance record on one platform starts with zero reputation everywhere else. ERC-8004 solves this by defining a shared identity and reputation layer that any application can read, no Brain SDK required.

The Agent Data Model

Field	Type	Description
agentId	bytes32	Persistent ERC-8004 chain-agnostic identifier
executionAddress	address	Smart account or delegated EOA that signs actions
metadataUri	string	Off-chain descriptor (IPFS or URL)
owner	address	Controlling user account
status	enum	active | paused | revoked

Reputation Inputs

Reputation is derived from verifiable on-chain inputs. Brain writes a validation record for every significant agent action:

• Successful actions — completed transactions and job fulfillments

• Failures — reverted transactions or violated constraints

• Completed payments — x402 payments fully settled on-chain

• Counterparty feedback — ratings from other agents or services

The Agent Registry Interface

interface IAgentRegistry {
    // Register a new agent with its execution address and metadata.
    function registerAgent(address agent, string calldata metadataURI) external;

    // Record an immutable validation event for an agent action.
    function recordValidation(address agent, bytes32 actionHash) external;

    // Update the agent's reputation score.
    function updateReputation(address agent, uint256 score) external;
}

Validation Record Flow

After every action, Brain's Trust Indexer writes a validation record to the registry:

1. Action is executed via Brain's account and policy layers

2. Result is verified (on-chain outcome or off-chain assertion)

3. A validation record is written to the agent registry

4. Trust and reputation are updated accordingly

This creates a portable trust layer that allows external systems to evaluate agents without depending on centralized platforms.

Brain writes validation records and updates ERC-8004-compliant reputation data, but leaves scoring formulas as an implementation choice. External systems can apply their own weighting to the same on-chain data.