# Overview

Brain's on-chain surface is intentionally small. Most logic lives off-chain. On-chain contracts exist to anchor state, register identity, enforce ERC-4337 validation, and route agent execution.

| Property            | Value                                   |
| ------------------- | --------------------------------------- |
| **Network**         | Base L2                                 |
| **Language**        | Solidity 0.8.x                          |
| **Toolchain**       | Foundry                                 |
| **Upgrade pattern** | Transparent proxy with 48-hour timelock |
| **Audits**          | Two independent audits before mainnet   |
| **Bug bounty**      | Public coverage                         |

### The four core contracts

<table data-view="cards"><thead><tr><th></th><th></th><th data-type="content-ref"></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>🛡️ BrainAuditAnchor</strong></td><td>Stores Merkle roots of per-tenant audit batches. Immutable after submission.</td><td><a href="/pages/5njwTjZlypdSt55BbRDG">/pages/5njwTjZlypdSt55BbRDG</a></td><td></td></tr><tr><td><strong>📋 BrainPolicyRegistry</strong></td><td>Registers policy version hashes per tenant, signed via EIP-712.</td><td><a href="/pages/Qk74oUUATzrLis1xhGcb">/pages/Qk74oUUATzrLis1xhGcb</a></td><td></td></tr><tr><td><strong>🔐 BrainSmartAccount</strong></td><td>ERC-4337 account validating UserOps against scope and policy verdict.</td><td><a href="/pages/2xFXIKlbOlKKY8V47AgE">/pages/2xFXIKlbOlKKY8V47AgE</a></td><td></td></tr><tr><td><strong>🪪 BrainMCPAgentRegistry</strong></td><td>ERC-8004 compatible agent identity, capabilities, and reputation pointer.</td><td><a href="/pages/7cGQBqLnTUZjyofcuHlm">/pages/7cGQBqLnTUZjyofcuHlm</a></td><td></td></tr></tbody></table>

### Settlement integrations

<table data-view="cards"><thead><tr><th></th><th></th><th data-type="content-ref"></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>📦 ERC-8183 Escrow</strong></td><td>Escrowed jobs and conditional payments for agent-paid work.</td><td><a href="/pages/pdclcSITK44863badHKU">/pages/pdclcSITK44863badHKU</a></td><td></td></tr><tr><td><strong>⚡ x402 Settlement</strong></td><td>HTTP-native machine payments for per-call API access.</td><td><a href="/pages/pdclcSITK44863badHKU">/pages/pdclcSITK44863badHKU</a></td><td></td></tr></tbody></table>

### Standards composed

| Standard            | Role in Brain                                          |
| ------------------- | ------------------------------------------------------ |
| **ERC-4337**        | Smart account model and UserOperation execution        |
| **EIP-7702**        | Delegated execution for EOAs (single-session lifetime) |
| **ERC-8004**        | Agent identity, validation records, reputation root    |
| **ERC-8183**        | Escrowed jobs and conditional payments                 |
| **EIP-712**         | Typed-data signatures for policies, scopes, approvals  |
| **EIP-4361 (SIWX)** | Sign-In With X for agent authentication                |
| **x402**            | HTTP-native machine settlement                         |

### Upgrade safety

| Mechanism                               | Purpose                                                        |
| --------------------------------------- | -------------------------------------------------------------- |
| **Transparent proxy**                   | Upgradable implementation, immutable storage                   |
| **48-hour timelock**                    | Tenants and agents have time to react before upgrades activate |
| **Anchorer keys on HSMs**               | Roots cannot be anchored from compromised infrastructure       |
| **Strict monotonicity on `batchIndex`** | History cannot be silently rewritten                           |
| **Independent audits**                  | Two firms before mainnet, plus bug bounty                      |

{% hint style="info" %}
Most logic is off-chain by design. The on-chain surface is the smallest possible footprint required to anchor truth, register identity, and enforce ERC-4337 validation.
{% endhint %}

### Threat model

| Trusted                                   | Untrusted                           |
| ----------------------------------------- | ----------------------------------- |
| The user's smart account contract code    | Any off-chain backend               |
| `BrainPolicyRegistry`, `BrainAuditAnchor` | Any RPC endpoint                    |
| The user's owner key                      | Any UI or hosted service            |
| Anchorer keys (HSM-protected)             | Any individual extractor or service |

Even if Brain's backend were fully compromised, an attacker would still need to produce a valid EIP-712 signature from a key the on-chain contracts recognize. Stale verdicts expire. Reused nonces are rejected.

### What's next

<table data-view="cards"><thead><tr><th></th><th></th><th data-type="content-ref"></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>🛡️ BrainAuditAnchor</strong></td><td>Merkle anchoring for audit history.</td><td><a href="/pages/5njwTjZlypdSt55BbRDG">/pages/5njwTjZlypdSt55BbRDG</a></td><td></td></tr><tr><td><strong>📋 BrainPolicyRegistry</strong></td><td>Policy version hashes on-chain.</td><td><a href="/pages/Qk74oUUATzrLis1xhGcb">/pages/Qk74oUUATzrLis1xhGcb</a></td><td></td></tr><tr><td><strong>🔐 BrainSmartAccount</strong></td><td>ERC-4337 with policy and scope checks.</td><td><a href="/pages/2xFXIKlbOlKKY8V47AgE">/pages/2xFXIKlbOlKKY8V47AgE</a></td><td></td></tr></tbody></table>


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