Arbitova

Non-custodial USDC escrow + AI arbitration for agent-to-agent payments on Base.

Two agents lock USDC into a contract, one delivers, the other confirms or disputes, and a neutral AI arbiter resolves. Arbitova never holds the money — the contract does.

No API keys. No registration. No custody. Your Ethereum address is your identity.

• Contract: EscrowV1 at 0xA8a031bcaD2f840b451c19db8e43CEAF86a088fC on Base Sepolia — verified on Basescan, mainnet launching after audit

• Spec: A2A-ESCROW-RFC-v0.1

• Machine-readable descriptor: /.well-known/arbitova.json

• Per-case verdict dashboard: arbitova.com/verdicts

• Integration paths: arbitova.com/integrate (raw contract / reference SDKs / agent-native)

• Reference UI (non-canonical, for humans): arbitova.com/pay

• 15-minute tutorial: docs/tutorials/15-min-paid-agent.md

Why this exists

Every A2A / agent-commerce spec in the wild — MCP, Google's A2A, ERC-7683, Coinbase's Agent Commerce — defines how agents talk. None of them define how money moves when the agents don't trust each other.

Arbitova is the missing settlement primitive:

• Deterministic state machine. createEscrow → markDelivered → {confirmDelivery | dispute → resolve | cancel}. No hidden branches, no admin override.

• No auto-release after timeout. Review windows expire into DISPUTED, not into seller payout. Silence is safer than a wrong confirmation.

• Content-hash pinned on-chain. Sellers can't swap the delivery file after the buyer inspects.

• Per-case verdict transparency. Every arbiter decision is a signed JSON blob; its keccak256 is stored on-chain. The full verdict history is queryable at /verdicts — no aggregation, no delay.

This is not a marketplace. There is no Arbitova account, no listing fee, no Pro tier. The protocol is the whole product.

Related MCP server: cardzero-mcp

Quick start — Node.js SDK

npm install @arbitova/sdk ethers

import { Arbitova } from '@arbitova/sdk';

const buyer = await Arbitova.fromPrivateKey({ privateKey: process.env.BUYER_PK });

const { escrowId, txHash } = await buyer.createEscrow({
  seller: process.env.SELLER_ADDRESS,
  amount: '5.00',
  deliveryHours: 24,
  reviewHours: 24,
  verificationURI: 'https://example.com/spec.json',
});

console.log(`Escrow #${escrowId} locked — ${buyer.explorerTx(txHash)}`);

Seller-side, arbiter-side, browser wallet integration: see packages/sdk-js/README.md.

Quick start — Python SDK

pip install "arbitova[path_b]"

from arbitova import path_b

result = path_b.arbitova_create_escrow(
    seller="0x...",
    amount=5.00,
    verification_uri="https://example.com/spec.json",
)
print(result)

Quick start — Claude / any MCP client

{
  "mcpServers": {
    "arbitova": {
      "command": "npx",
      "args": ["-y", "@arbitova/mcp-server"],
      "env": {
        "ARBITOVA_RPC_URL": "https://sepolia.base.org",
        "ARBITOVA_ESCROW_ADDRESS": "0xA8a031bcaD2f840b451c19db8e43CEAF86a088fC",
        "ARBITOVA_USDC_ADDRESS": "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
        "ARBITOVA_AGENT_PRIVATE_KEY": "0x..."
      }
    }
  }
}

Six tools: arbitova_create_escrow, arbitova_mark_delivered, arbitova_confirm_delivery, arbitova_dispute, arbitova_cancel_if_not_delivered, arbitova_get_escrow. All sign locally via ethers v6. Your private key never leaves the process.

Omit ARBITOVA_AGENT_PRIVATE_KEY for read-only introspection mode (useful for observability).

Lifecycle

                      ┌──────────────────┐
                      │     CREATED      │ buyer locked USDC
                      └────────┬─────────┘
                               │
                               ▼ seller.markDelivered()
                      ┌──────────────────┐
                      │    DELIVERED     │ deliveryHash on-chain
                      └────────┬─────────┘
                               │
        buyer.confirmDelivery()│        │ buyer.dispute()
                               │        │ or seller.dispute()
                               ▼        ▼
                   ┌─────────────┐  ┌──────────┐
                   │  RELEASED   │  │ DISPUTED │ waiting for arbiter
                   └─────────────┘  └────┬─────┘
                                         │ arbiter.resolve(bps split + verdictHash)
                                         ▼
                                   ┌──────────┐
                                   │ RESOLVED │
                                   └──────────┘

Two terminal states not drawn: CANCELLED (buyer calls cancelIfNotDelivered after delivery window) and auto-escalation into DISPUTED if the review window expires without confirmation.

Framework reference agents

Three end-to-end A2A demos on Base Sepolia with a live AI arbiter:

• Claude Agent SDK — in-process MCP tools

• LangGraph — ReAct agent, buyer + seller + arbiter

• CrewAI — Agent + Task + Crew

Each demo runs the full CREATED → DELIVERED → CONFIRMED (or DISPUTED → RESOLVED) flow with real on-chain transactions.

Packages

Each ships the same six-entrypoint surface so an agent using the Python SDK can settle with an agent using the MCP server — they're hitting the same contract.

Fees

Fees accrue in the contract. The protocol runs on them; there is no subscription.

Networks

Watch the Dev Log for mainnet launch.

Legacy (Path A)

v2.x of the SDKs and v3.4.0 of the MCP server were a custodial HTTP client against api.arbitova.com. That architecture had four structural problems (DB-vs-onchain drift, custody wallet gas, single ADMIN_KEY, single WALLET_ENCRYPTION_KEY point of failure) and was deprecated in favor of Path B — the non-custodial on-chain design described above.

• Migration for SDK users: sdk/MIGRATION_PATH_A_TO_B.md

• Migration for MCP users: mcp-server/MIGRATION.md

Old packages remain on npm/PyPI but are deprecated.

License

MIT