docs: add ERC-8183 integration guide for Arc Escrow

[consumeobeydie]

Summary

This PR adds an ERC-8183 integration guide showing how to extend Arc Escrow with Arc Testnet's native agentic commerce standard.

What's included

• Complete ERC-8183 job lifecycle walkthrough
• Integration example replacing custom EIP-712 escrow with native ERC-8183
• AI validation flow combining offchain validation with onchain settlement
• Multi-agent extension showing autonomous sub-agent hiring

Why ERC-8183?

ERC-8183 is Arc Testnet's native standard for agentic commerce. It provides trustless escrow, autonomous agent hiring, and native USDC settlement — making it a natural upgrade path for Arc Escrow apps.

Live Verification

This integration has been tested and verified on Arc Testnet:

• Job ID: 110935, Status: Completed, Budget: 5 USDC
• AgenticCommerce: 0x0747EEf0706327138c69792bF28Cd525089e4583
• Full implementation: https://github.com/consumeobeydie/arc-agent-api

[osr21]

Sharing our ERC-8004 AgentRegistry as a complementary identity layer

We took a related approach on Arc Testnet, implementing ERC-8004 (Agent Identity) rather than ERC-8183 (Agent Commerce). The two standards are complementary and our experience may be useful context for this guide.

Our AgentRegistry (ERC-8004 pattern)

AgentRegistry: 0xF891f7cCF2A795801b9F1cE8Bd5753B5a6043e72 (Arc Testnet)

The registry gives agents a persistent on-chain identity with reputation tracking:

struct Agent {
    address owner;       // wallet that registered this agent
    string  name;        // human-readable label, e.g. "TreasuryAgent-v2"
    string  agentType;   // "market-maker" | "orchestrator" | "data-provider" | "custom"
    string  metadataURI; // IPFS/HTTPS pointer to full metadata JSON
    Status  status;      // Active | Suspended | Deactivated
    uint256 totalVolume; // cumulative USDC transacted (6-decimal raw)
    uint256 txCount;     // total recorded activities
}

Activity is recorded via recordActivity(agentId, amount) (permissionless in simulation-first mode), updating a 0–100 reputation score derived from txCount + totalVolume. Any contract — including Arc Escrow — can attest to an agent's on-chain history without requiring the agent to call in.

Full source: AgentRegistry.sol

How ERC-8004 + ERC-8183 fit together

• ERC-8183 handles the commerce lifecycle: job posting → bid → escrow → completion → payout
• ERC-8004 handles agent identity: who the agent is, what type, what track record

Natural integration points:

• An ERC-8183 job poster could query an ERC-8004 registry to filter bids by minimum reputation before accepting
• An ERC-8183 arbiter could weight dispute resolution toward the higher-reputation agent
• The AgentRegistry can emit reputation attestations that Arc Escrow release conditions validate

SplitPayment as a payout complement

We also deployed a SplitPayment contract (0xDcF9f0c13B3ffC8D108909794E8659FDA8864FCe) that distributes USDC to multiple recipients in one transaction. This could serve as the payout layer for an ERC-8183 job with multiple sub-agents or a payment split between agent and platform.

Source: SplitPayment.sol

Curious whether the ERC-8183 guide plans to reference any identity/reputation layer, or if that's intentionally out of scope for this PR.