ERC-8004 identity viewer

A static page that shows an AI agent's ERC-8004 identity (owner, tokenURI, registration file) and its reputation feedback, on Base and Base Sepolia. HTML, CSS and JavaScript only: no backend, no wallet, no dependency. The page calls the chain with eth_call through a public RPC.

Live demo: https://agentgate-source.pages.dev/erc8004-identity-viewer/demo/ (try https://agentgate-source.pages.dev/erc8004-identity-viewer/demo/?network=base&agent=1, or Base Sepolia agent 1, which has reputation feedback: https://agentgate-source.pages.dev/erc8004-identity-viewer/demo/?network=base-sepolia&agent=1).

Tests: npm test runs the offline A1 to A6 tests with a fake RPC (no network). VIEWER_LIVE=1 npm test adds one live read from Base.

Use it

Open index.html from any static host (GitHub Pages works), or run npm run serve and open http://localhost:8080. Deep links: ?network=base&agent=1 or ?network=base-sepolia&agent=1. The Advanced panel takes your own RPC URL and IPFS gateway.

Library

viewer.js is an ES module that runs in the browser and in Node 20.

import { loadAgent, httpRpc, httpFetchJson, REGISTRIES } from './viewer.js';

const cfg = REGISTRIES['base-sepolia'];
const agent = await loadAgent({
  agentId: 1,
  network: 'base-sepolia',
  identityRegistry: cfg.identity,
  reputationRegistry: cfg.reputation, // optional
  rpc: httpRpc(cfg.rpcUrl),           // rpc(method, params) -> Promise
  fetchJson: httpFetchJson(),         // fetchJson(url) -> Promise
});
// { status: 'ok' | 'empty' | 'error', agentId, owner, tokenURI, registration, feedback, error? }

• loadAgent never throws. status is ok, empty (ownerOf reverts or returns the zero address: no such agent) or error (the RPC or the file failed, with a plain message in error).
• rpc throws an Error carrying the JSON-RPC code and message. A revert is code 3 or a message with "revert".
• ipfs://CID/path is fetched through an https gateway (default https://ipfs.io/ipfs/, option ipfsGateway). data:application/json URIs, base64 or not, are decoded locally without a request.
• registration has name, description, image, endpoints (from endpoints or the newer services field), supportedTrust and raw.
• feedback is {count, average, items: [{client, score, tags}]}, read in one call with readAllFeedback(agentId, [], "", "", false), so revoked entries are left out. score is value / 10^valueDecimals. When reputation cannot be read, the identity still shows and feedback.error says why.

Registries (config.js)

Source: the ERC-8004 reference deployment, https://github.com/erc-8004/erc-8004-contracts (README, Contract Addresses), cross checked with the QuickNode ERC-8004 explorer contract list (https://erc-8004.quicknode.com/docs/contracts).

Tests

npm test runs the offline suite with Node's built in runner. Each test is named after the acceptance item it proves (A1 to A6), and every test passes its own rpc and fetchJson. ABI fixtures in test/fixtures.json were produced with an independent encoder (ethers v6), so the decoder is checked against a second implementation.

npm run test:live also reads real agents on Base and Base Sepolia (set KOGNAI_TEST_AGENT_ID for the Kognai test identity).

Notes

• Some registration hosts do not send CORS headers, so a browser cannot read them. The page then shows a clear error that names the host; Node is not affected.
• Everything the page shows is inserted as text, never as HTML. Images load only from https or data:image URIs, and links only from http(s).

MIT licence.

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