@odatano/nightgate-mcp

MCP server that lets AI agents use NIGHTGATE, the Midnight blockchain attestation layer: anchor documents, prove zero-knowledge predicates over hidden fields, manage disclosure grants, verify everything against live contract state, and poll async jobs. Wallet lifecycle (connect, send, deploy) is deliberately not exposed.

Requirements

• Node.js >= 20
• A running NIGHTGATE instance (>= 0.15.0 for the full tool set; 0.14.0 works without the equality/membership tools)

Getting a NIGHTGATE instance

The fastest way is the official Docker image; no Node setup, no host app (published from the NIGHTGATE repo on every release, details in its docs/docker.md):

docker run -d --name nightgate -p 4004:4004 \
  -e ENCRYPTION_KEY=$(openssl rand -hex 32) \
  -e NIGHTGATE_HTTP_PASSWORD=change-me \
  -v nightgate-data:/data \
  ghcr.io/odatano/nightgate:latest

That container targets Midnight preprod by default, serves with HTTP basic auth (nightgate / your password), persists its database in the nightgate-data volume, and proves in-process (wasm), so no proof server is needed to start. Point this MCP server at it with:

NIGHTGATE_BASE_URL=http://localhost:4004
NIGHTGATE_USERNAME=nightgate
NIGHTGATE_PASSWORD=change-me

For agent operation, create a scoped grant once (as the operator, e.g. via curl against createAgentGrant) and hand the returned ngat_... token to the agent as NIGHTGATE_TOKEN; the write tools are then limited to the grant's allowlist, budget and pinned session.

Alternatively any CAP app using the @odatano/nightgate plugin works, e.g. the NIGHTGATE repo itself via npm run dev.

Setup

npm install
npm run build

Configuration is environment-driven:

Variable	Default	Purpose
NIGHTGATE_BASE_URL	http://localhost:4004	NIGHTGATE host app
NIGHTGATE_USERNAME / NIGHTGATE_PASSWORD	unset	Basic auth (CAP dev/mocked auth)
NIGHTGATE_TOKEN	unset	ngat_... agent-grant token (sent as x-agent-token, combinable with basic auth) or a plain bearer token
NIGHTGATE_SERVICE_PATH	/api/v1/nightgate	OData service path
NIGHTGATE_TIMEOUT_MS	30000	Per-request timeout

Use with Claude Code

claude mcp add nightgate \
  --env NIGHTGATE_BASE_URL=http://localhost:4004 \
  --env NIGHTGATE_USERNAME=alice \
  -- node /path/to/NIGHTGATE-MCP/dist/index.js

Or in a project .mcp.json:

{
  "mcpServers": {
    "nightgate": {
      "command": "node",
      "args": ["/path/to/NIGHTGATE-MCP/dist/index.js"],
      "env": {
        "NIGHTGATE_BASE_URL": "http://localhost:4004",
        "NIGHTGATE_USERNAME": "alice"
      }
    }
  }
}

Tools

Tool	What it does
verify_attestation	Live-state check that a payload hash is attested in an AttestationVault (crawler-free, optional content-root check, optional cross-network read)
verify_predicate	Live-state check that a ZK claim was recorded true on-chain, id-free: numeric predicates, bytesEquality (+ expectedDigest) and setMembership (+ setRoot)
verify_predicate_attestation	Verify a server-issued predicate attestation by its row id
verify_document	Verify an anchored document by document id + sha256
prepare_document_proof	Canonicalize a document into payloadHash + Merkle contentRoot + per-field proof inputs, numeric and kind: "bytes" string fields (synchronous, NIGHTGATE >= 0.14.0; bytes kind >= 0.15.0)
prepare_membership_set	Build the canonical allow-list set tree: setRoot for verifiers, inclusion path for provers (synchronous, NIGHTGATE >= 0.15.0)
attest_agent_output	Anchor agent-output provenance (canonical envelope, third-party verifiable; async job, NIGHTGATE >= 0.14.0)
anchor_document	Anchor a document content hash on-chain (async job)
prove_field_predicate	ZK proof that a hidden document field satisfies a threshold, without revealing it (async job)
prove_field_equality	ZK proof that a string field carries exactly the value behind a public digest (async job, NIGHTGATE >= 0.15.0)
prove_field_membership	ZK proof that a hidden string field is one of a public allow-list, without revealing which (async job, NIGHTGATE >= 0.15.0)
prove_field_predicates_batch	Up to 8 field claims on one document in ONE transaction, any mix of numeric / equality / membership (async job)
grant_disclosure / revoke_disclosure	Attester-only on-chain disclosure ACL (async jobs)
get_job_status	Poll an async NIGHTGATE job until succeeded/failed

All verification tools return verified: false as a clean negative rather than an error when the attestation or proof is absent. Write tools require a connected wallet session (sessionId); creating sessions stays outside MCP by design.

Integration check

npm run integration

Runs an in-memory MCP client against the server: asserts the tool set, schemas, and argument validation. Optional live round-trip:

NIGHTGATE_LIVE=1 NIGHTGATE_BASE_URL=... NIGHTGATE_USERNAME=... \
NIGHTGATE_TEST_CONTRACT=<vault address> NIGHTGATE_TEST_PAYLOAD_HASH=<64 hex> \
npm run integration

License

Apache-2.0