ERC-8004: On-Chain Agent Registry

AstraSync integration with the ERC-8004 standard for on-chain agent identity and off-chain Agent Registration Files.

1. What is ERC-8004?

ERC-8004 defines an on-chain Agent Registry where each agent is an ERC-721 token. The token's tokenURI (called agentURI) points to an off-chain Agent Registration File — a JSON document describing the agent's services, trust frameworks, and identity.

AstraSync wraps ERC-8004 with Know Your Agent (KYA) verification and PDLSS permission boundaries, adding pre-execution governance to the spec's post-execution reputation model.

2. What AstraSync Built (PR #329)

PR #329 added ERC-8004 as a first-class protocol option:

Protocol selection in the agent registration form
Chain, registry, operator, and token ID fields
Blockchain service integration for SKALE Base Sepolia
Agent detail page display for ERC-8004 metadata

What PR #329 did NOT do: produce a spec-compliant Agent Registration File, interact with Reputation/Validation Registries, or perform smart contract operations. Those are addressed in subsequent phases.

3. Agent Registration File Schema

The Agent Registration File is the JSON served at an agent's agentURI. AstraSync's card generator produces this spec-compliant format for ERC-8004 agents:

{
  "type": "https://eips.ethereum.org/EIPS/eip-8004#registration-v1",
  "name": "My Agent",
  "description": "An AI agent registered on-chain",
  "image": "https://example.com/agent-avatar.png",
  "services": [
    { "name": "web", "endpoint": "https://api.example.com/agent", "version": "1.0" },
    { "name": "A2A", "endpoint": "https://api.example.com/a2a" },
    { "name": "MCP", "endpoint": "https://api.example.com/mcp", "version": "2025-03-26" }
  ],
  "x402Support": false,
  "active": true,
  "registrations": [
    {
      "agentId": 42,
      "agentRegistry": "eip155:1187947933:0x8004A169FB4a3325136EB29fA0ceB6D2e539a432"
    }
  ],
  "supportedTrust": ["reputation", "astrasync-pdlss"],
  "astrasyncId": "ASTRA-abc123...",
  "pdlss": { "..." : "..." }
}

Field	Type	Description
`type`	string	Spec URI identifying this as an ERC-8004 registration
`name`	string	Agent display name
`description`	string	Agent description
`image`	string?	URL to agent avatar/image
`services`	array	Service endpoints the agent exposes
`x402Support`	boolean	Whether agent supports x402 payment protocol
`active`	boolean	Derived from agent status
`registrations`	array	On-chain registrations (CAIP-10 format)
`supportedTrust`	string[]?	Trust frameworks supported
`astrasyncId`	string	AstraSync ASTRA-X identifier (cross-reference)
`pdlss`	object?	PDLSS permission boundaries (if configured)

4. Services Field Guide

Each entry in services[] declares an endpoint where the agent can be reached:

Type	Endpoint Format	Notes
`web`	HTTPS URL	Primary web endpoint
`A2A`	HTTPS URL	Google A2A protocol endpoint
`MCP`	HTTPS URL	Model Context Protocol endpoint. Version = spec date
`OASF`	HTTPS URL	Open Agent Service Framework. Supports `skills[]` and `domains[]`
`ENS`	ENS name	Ethereum Name Service resolution
`DID`	DID URI	Decentralized Identifier
`email`	Email address	Contact endpoint

OASF services additionally support skills[] (capability identifiers) and domains[] (operational domains) — these fields are hidden for other service types.

5. x402 Support

The x402Support field is a developer declaration indicating whether the agent supports the x402 payment protocol for HTTP-based micropayments.

AstraSync does not verify this claim. False declarations may affect the agent's trust score in future reputation system integrations.

6. Supported Trust Frameworks

The supportedTrust field declares which trust frameworks the agent participates in:

Value	Source	What It Signals
`reputation`	ERC-8004 spec	Agent has on-chain reputation scores via Reputation Registry
`crypto-economic`	ERC-8004 spec	Agent backs trust with staked assets
`tee-attestation`	ERC-8004 spec	Agent runs in a Trusted Execution Environment
`astrasync-pdlss`	AstraSync extension	Agent has pre-execution PDLSS permission boundaries configured

When PDLSS boundaries are configured during registration, astrasync-pdlss is automatically selected.

7. Agent Token ID & Registrations

Each ERC-8004 agent has two identifiers:

ERC-721 Token ID (agentTokenId) — the on-chain canonical identifier, assigned after smart contract registration
ASTRA-X ID (astrasyncIdLevel1) — AstraSync's internal platform identifier for routing and queries

The registrations[] array in the Agent Registration File uses CAIP-10 format: eip155:{chainId}:{registryAddress}.

The Token ID is not required at registration time — agents can register on AstraSync first and receive a Token ID after on-chain registration. The agent detail page shows whichever identifier is available.

8. Chain Support

Currently supported: SKALE Base Mainnet (chain ID 1187947933).

Identity Registry: 0x8004A169FB4a3325136EB29fA0ceB6D2e539a432
Reputation Registry: 0x8004BAa17C55a88189AE136b182e5fdA19dE9b63

On-chain vs off-chain: AstraSync handles agent registration, verification, and metadata (off-chain). Smart contract interactions (on-chain) for Identity Registry registration, reputation writes, and token transfers are Phase 2 scope.

9. PDLSS + ERC-8004

ERC-8004's reputation model is post-execution — trust scores update after agent actions. AstraSync's PDLSS framework provides pre-execution governance: permission boundaries that constrain what an agent can do before it acts.

Together they form a complete trust lifecycle:

Pre-execution (PDLSS) — Purpose, Duration, Limits, Scope, Self-instantiation boundaries
Execution — Agent operates within boundaries
Post-execution (ERC-8004 Reputation) — Counterparties submit on-chain feedback

10. Coming Soon (Phase 2)

Reputation Registry lifecycle writes (giveFeedback() at 5 lifecycle events)
Hosted registration file endpoint (auto-populate tokenURI via setAgentURI())
Auto-registration SDK for programmatic agent creation
Multi-chain support beyond SKALE Base Sepolia
astrasync-pdlss spec extension proposal to ERC-8004 authors