Northveil — Non-Custodial Agent Wallet & MCP Control Plane

Northveil is a strictly non-custodial control plane and Model Context Protocol (MCP) server for AI agents (Claude Desktop, Cursor, custom autonomous agents).

Core Invariant

The AI never holds keys. The server never holds a full key. The agent proposes an operation. A grant + policy engine decides if it can run. If approval is required, the user signs with a passkey. Signing happens by threshold MPC across isolated parties/TEEs. The agent only ever receives a derived result (tx hash, signature, scoped token) — never a private key, seed, or MPC share.

🔌 Official MCP Gateway Endpoints

Single Universal URL: https://mcp.northveil.xyz/mcp is the universal endpoint for every user. User authentication (OAuth 2.0 / Bearer token) binds directly to the user's primary vault. No ?wallet_address= query parameter is needed in the URL.

Related MCP server: SE2-Minikit MCP Server

🛡️ Interactive In-Chat UI (MCP Apps)

Northveil serves interactive cards conforming to the MCP Apps specification (text/html;profile=mcp-app):

• ui://northveil/send — In-chat transfer approval card

• ui://northveil/swap — In-chat token swap staging card

• ui://northveil/deploy — In-chat smart contract deployment & execution card

• ui://northveil/status — Live spend request polling & transaction confirmation card

• ui://northveil/read — Vault balances and multi-chain portfolio rollups

Tool responses return _meta.ui.resourceUri so supporting clients render cards directly in the conversation. pure-text clients cleanly fallback to standard markdown text.

🏛️ Ecosystem Monorepo Architecture

Northveil/
├── mcp-server/                   # Non-custodial MCP Gateway (HTTP, SSE, OpenAPI, stdio)
│   ├── src/                      # Modular control plane (grantEngine, approvals, passkey, mpcAdapter)
│   ├── test/                     # Security and policy invariant test suites
│   └── supabase/                 # Non-custodial PostgreSQL schema & RLS policies
├── sdk/                          # Official TypeScript / JavaScript Client (npm: northveil-sdk)
├── wallet/                       # Next.js App Router biometric passkey control plane (wallet.northveil.xyz)
├── docs/                         # Protocol architecture specifications & database schemas
└── supabase/                     # Supabase migrations & row-level security

🔐 Non-Custodial MPC Control-Plane Architecture

1. Zero Server-Side Private Key Storage: Northveil does not store your seed; Turnkey holds key material. No private keys, seed phrases, or MPC secret shares exist on the server, in memory as long-lived secrets, in Postgres, in environment variables, or in git.

2. WebAuthn Biometric Passkey Gating: Operations under Always Ask mode generate single-use approval tickets with 10-minute TTL. The challenge commits cryptographically to sha256(canonicalUnsignedTx).

3. Autonomous Agent Spending Scopes: Users grant AI agents scoped operational budgets with maximum per-transaction caps, rolling 24-hour daily limits, and recipient allowlists. Non-zero calldata is forbidden in autonomous mode.

4. Isolated Threshold MPC: Signing occurs inside hardware-isolated enclaves (Turnkey TEE partitions) upon validation of policy and cryptographic passkey assertion evidence. On hosted environments, Northveil cannot sign with the operator key alone; the code throws ORG_ROOT_SIGN_FORBIDDEN unless stamped by the user or scoped delegate (see SECURITY.md).

📄 License

MIT License © 2026 Northveil Protocol.