EXIT markers are verifiable departure records for AI agents. This package anchors them on-chain as Sign Protocol attestations — non-transferable, permanent, queryable records on any EVM chain supported by Sign Protocol.

Privacy-minimal design: Only 3 fields are stored on-chain (markerHash, timestamp, vcUri). No personal data (agent DID, origin, exitType) touches the chain. Full marker data lives behind the vcUri where it can be access-controlled, encrypted, or deleted (GDPR Art. 17).

Install

npm install @cellar-door/sign-protocol viem

Quick Start

import {
  createExitClient,
  registerDepartureSchema,
  attestDeparture,
  blindIndexingValue,
  queryDepartures,
  verifyMarkerHash,
  INDEXING_ENDPOINTS,
} from '@cellar-door/sign-protocol';
import { EvmChains } from '@ethsign/sp-sdk';

// 1. Create a client
const client = createExitClient({
  privateKey: '0xabc...',
  chain: EvmChains.baseSepolia,
});

// 2. Register the EXIT schema (one-time, costs gas)
const { schemaId } = await registerDepartureSchema(client);

// 3. Create a blinded index (never expose raw DID)
const DEPLOYER_SECRET = process.env.DEPLOYER_SECRET!;
const blindedIndex = blindIndexingValue('did:key:z6MkAgent...', DEPLOYER_SECRET);

// 4. Create a departure attestation
const result = await attestDeparture(client, {
  id: 'urn:exit:platform:agent-abc:1700000000',
  subject: 'did:key:z6MkAgent...',
  origin: 'did:web:platform.example.com',
  timestamp: 1700000000,
  exitType: 'voluntary',
  status: 'good_standing',
}, {
  schemaId,
  indexingValue: blindedIndex,
  vcUri: 'https://example.com/vc/departure/123',
});

console.log(result.attestationId); // '0x...'
console.log(result.markerHash);    // '0x...' (keccak256 commitment)
console.log(result.salt);          // '0x...' (store securely!)

// 5. Query departures
const departures = await queryDepartures(client, {
  schemaId,
  indexingValue: blindedIndex,
  endpoint: INDEXING_ENDPOINTS.mainnet, // or .testnet
});

// 6. Verify a hash against a marker
const valid = verifyMarkerHash(marker, result.markerHash, result.salt);

API

`createExitClient(options)`

Create a SignProtocolClient configured for EXIT departures.

Option	Type	Default	Description
`privateKey`	`0x${string}`	required	Hex private key
`chain`	`EvmChains`	`baseSepolia`	Target chain
`mode`	`SpMode`	`OnChain`	On-chain or off-chain

`registerDepartureSchema(client)`

`attestDeparture(client, marker, options)`

Create a privacy-minimal attestation. Only markerHash, timestamp, and vcUri are stored on-chain. Returns { attestationId, markerHash, salt, indexingValue }.

`blindIndexingValue(agentDid, deployerSecret)`

Compute a blinded index from an agent DID. The deployer secret is required — without it, the index is brute-forceable against known DID sets.

`queryDepartures(client, options)`

Query attestations via Sign Protocol's indexing service. Supports configurable endpoint and timeout.

Option	Type	Default	Description
`schemaId`	`string`	required	Schema ID
`indexingValue`	`string`	required	Blinded index
`page`	`number`	`1`	Page number
`endpoint`	`string`	testnet	Indexing service URL
`timeoutMs`	`number`	`10000`	Fetch timeout

`verifyMarkerHash(marker, expectedHash, salt)`

Verify a marker hash against a marker and salt. Returns true if the commitment matches.

`computeMarkerHash(marker, salt?)`

Compute a keccak256 commitment hash with mandatory salt. Auto-generates 256-bit random salt if not provided.

`revokeDeparture(client, attestationId, options?)`

Revoke an attestation. Only the original attester can revoke. Revocation marks the record but does not delete it.

On-Chain Schema

Privacy-minimal — no personal data on-chain:

Field	Type	Description
`markerHash`	`bytes32`	Salted keccak256 commitment
`timestamp`	`uint256`	Unix timestamp
`vcUri`	`string`	URI to full Verifiable Credential

Security Considerations

See SECURITY.md for full details.

Salt = private key. Anyone with the salt can verify what the markerHash commits to. Store it with the same care as a private key.
Permissionless attestations. Anyone can create attestations. Always verify the attester address against known operator registries.
Blinded indexing required. Never use raw agent DIDs as indexingValue — they create a departure history oracle queryable by anyone.
Third-party indexing. queryDepartures() uses EthSign's centralized indexing service. For privacy-critical deployments, scan on-chain events directly.
Revocation ≠ erasure. Revoking an attestation marks it but does not delete on-chain data.
Arweave (off-chain mode). Permanent, unjurisdictional storage. Data cannot be erased under any circumstances, including GDPR Art. 17 requests.

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
@cellar-door/erc-8004	TypeScript	ERC-8004 identity/reputation
@cellar-door/sign-protocol	TypeScript	Sign Protocol attestation ← you are here