EXIT markers are verifiable departure records for AI agents. This package anchors them on-chain as EAS attestations — non-transferable, permanent, queryable records on Base L2 (or any EVM chain where EAS is deployed).

EAS attestations are inherently soul-bound — they cannot be transferred, sold, or traded. No SBT wrapper needed.

Install

npm install @cellar-door/eas

Quick Start

import { anchorExit, verifyAnchor, registerExitSchema, setExitSchemaUid } from '@cellar-door/eas';
import { Wallet, JsonRpcProvider } from 'ethers';

const provider = new JsonRpcProvider('https://mainnet.base.org');
const signer = new Wallet(process.env.PRIVATE_KEY!, provider);

// One-time: register the EXIT schema on Base
const { schemaUid } = await registerExitSchema({ chain: 'base', signer });

// Or configure a known schema UID
setExitSchemaUid('base', '0x...');

// Anchor an EXIT marker on-chain
const result = await anchorExit(marker, {
  chain: 'base',
  signer,
  vcUri: 'ipfs://bafybeig...',
});
console.log(`Anchored: ${result.uid}`);

// Verify an anchored attestation
const verification = await verifyAnchor(result.uid, { chain: 'base', provider });
if (verification.valid && !verification.revoked) {
  console.log(`Valid EXIT by ${verification.attestation.attester}`);
}

Three-Tier Schema System

Choose the right level of on-chain data exposure for your use case:

Mode	Schema	On-chain Data	Use Case
`full`	All fields	exitId, subjectDid, recipient, origin, timestamp, exitType, status, selfAttested, lineageHash, vcUri	Maximum queryability, public attestations
`minimal`	Hash + DID + URI	exitHash, subjectDid, vcUri	Reduced data, keeps DID for lookups
`commitment` (default)	Hash + URI only	exitHash, vcUri	True GDPR-safe — no personal data on-chain

Usage

// Commitment mode (default) — GDPR-safe, no personal data on-chain
await anchorExit(marker, { chain: 'base', signer });

// Minimal mode — commitment hash + DID + VC URI
await anchorExit(marker, { chain: 'base', signer, schemaMode: 'minimal' });

// Full mode — all fields on-chain for maximum queryability
await anchorExit(marker, { chain: 'base', signer, schemaMode: 'full' });

// Backwards compat: minimal: true still works
await anchorExit(marker, { chain: 'base', signer, minimal: true }); // → schemaMode: 'minimal'

Schema Registration

Each mode has its own schema UID (content-addressed). Register once per chain per mode:

await registerExitSchema({ chain: 'base', signer });                          // full
await registerExitSchema({ chain: 'base', signer, mode: 'minimal' });         // minimal
await registerExitSchema({ chain: 'base', signer, mode: 'commitment' });      // commitment

Off-chain Attestations

Off-chain attestations are signed EIP-712 data that can be stored anywhere.

// Create off-chain attestation
const result = await anchorExit(marker, {
  chain: 'base',
  signer,
  mode: 'offchain',
  schemaMode: 'commitment',
});

// Verify off-chain attestation
import { verifyOffchainAnchor } from '@cellar-door/eas';
const verification = verifyOffchainAnchor(result.offchainAttestation);

Deduplication: Off-chain attestations include a deterministic nonce in the refUID field (derived from keccak256(markerId + chain + timestamp)). Consumers should check refUID uniqueness to detect duplicates.

API

`anchorExit(marker, options)` → `AnchorResult`

Anchor an EXIT marker as an EAS attestation (on-chain or off-chain).

`verifyAnchor(uid, options)` → `VerifyResult`

Verify an on-chain EXIT attestation by UID. Auto-detects schema mode (full/minimal/commitment).

`verifyOffchainAnchor(attestation)` → `VerifyResult`

Verify an off-chain EXIT attestation. Checks EIP-712 signature and decodes schema data.

`revokeAnchor(uid, options)` → `RevokeResult`

Revoke an on-chain EXIT attestation.

`registerExitSchema(options)` → `RegisterSchemaResult`

`setExitSchemaUid(chain, uid, mode?)`

Configure a known schema UID without re-registering.

`didToAddress(did)` → `string`

Convert a DID to an Ethereum address. Supports did:ethr, did:pkh, and did:key.

Supported Chains

Chain	Cost/attestation	EAS Version
Base (default)	~$0.002	v1.0.1 (native)
Optimism	~$0.002	v1.0.1 (native)
Arbitrum	~$0.01	v0.26
Ethereum	~$5-30	v0.26
Sepolia (testnet)	Free	v0.26

DID Support

DID Method	Example	Mapping
`did:ethr`	`did:ethr:0x1234...`	Direct address extraction
`did:ethr` (network)	`did:ethr:base:0x1234...`	Direct address extraction
`did:pkh`	`did:pkh:eip155:8453:0x1234...`	Direct address extraction
`did:key`	`did:key:z6Mk...`	keccak256-derived address

Security Considerations

Attestations are permissionless. Anyone can create an attestation against EXIT schemas. Consumers MUST verify the attester address against a trusted set before accepting attestation data. See TRUST_MODEL.md for details and code examples.

For EU deployments, use schemaMode: 'commitment' to avoid storing personal data on-chain. See GDPR_GUIDE.md for the full deployment guide, crypto-shredding pattern, and DPIA requirements.

Additional Documentation

Document	Description
TRUST_MODEL.md	Permissionless attestation model & attester verification
DID_METHODS.md	DID method address mapping, synthetic addresses, key rotation
GDPR_GUIDE.md	EU deployment guide, commitment mode, crypto-shredding

Ecosystem

Package	Language	Description
cellar-door-exit	TypeScript	Core protocol (reference impl)
cellar-door-exit	Python	Core protocol
cellar-door-entry	TypeScript	Arrival/entry markers
@cellar-door/langchain	TypeScript	LangChain integration
cellar-door-langchain	Python	LangChain integration
@cellar-door/vercel-ai-sdk	TypeScript	Vercel AI SDK
@cellar-door/mcp-server	TypeScript	MCP server
@cellar-door/eliza	TypeScript	ElizaOS plugin
@cellar-door/eas	TypeScript	EAS attestation anchoring ← you are here
@cellar-door/erc-8004	TypeScript	ERC-8004 identity/reputation
@cellar-door/sign-protocol	TypeScript	Sign Protocol attestation