ai.vanticlabs/vantic

Verify an AI agent's payment authority: signed mandates, allowlists, and tamper-proof receipts.
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Verify an AI agent's payment authority: signed mandates, allowlists, and tamper-proof receipts.
Details

Kind: MCP servers
Topic: Finance & crypto
Publisher: ai.vanticlabs
Origin: official
Category: ferramentas
Transport: local
Version: 0.1.2
Last push: 2026-07-31T14:50:41Z
Repository state: ativo
Language: TypeScript
License: Apache-2.0
Added: 2026-08-29 03:00:43
Updated: 2026-08-29 03:00:43
Origin id: ai.vanticlabs/vantic
README

# Vantic

**A spending firewall and permission layer for AI agents.** Give your agent a signed budget it can't exceed — even if it gets prompt-injected — and get a tamper-proof receipt for everything it does.

Zero dependencies · TypeScript · Ed25519 + W3C DIDs · works with MCP, LangChain, or any tool-calling agent.

---

## The problem

Your AI agent can hold a wallet and call payment APIs. That's useful — and dangerous. One prompt injection from a poisoned web page, one hallucination, one bug, and your agent pays the wrong party. This is a documented, actively-exploited failure mode: agents tricked into wiring funds to attacker-controlled accounts.

## What Vantic does

You issue your agent a **signed mandate** — a budget, a per-transaction cap, allowed actions, and an allowlist of who it may pay — and wrap its money-moving calls (purchase, subscribe, transfer, pay-per-use, payout, refund — any action that moves value). From then on, an out-of-scope payment is **impossible**: the check runs *before* the money-moving code, so even a fully compromised model can't execute it. Every allowed action emits a **signed, tamper-proof receipt** — a clean audit trail, and evidence if a charge is ever disputed.

## Install

```bash
npm install @vantic/sdk
```

## Protect your agent in ~5 lines

```ts
import { generateKeyPair, issueMandate, AgentWallet } from "@vantic/sdk";

const owner = generateKeyPair();   // you (the principal)
const agent = generateKeyPair();   // your autonomous agent

// Authorize the agent: what it may pay for, ≤ $200 each, ≤ $500/week, only these counterparties.
const mandate = issueMandate({
  agent: agent.publicKey,
  principal: owner.publicKey,
  principalPrivateKeyPem: owner.privateKeyPem,
  ttlSeconds: 7 * 24 * 3600,
  scope: {
    budget: { currency: "USD", amount: 50000, windowSeconds: 7 * 24 * 3600 }, // $500 / 7 days
    maxPerTransaction: 20000,                                                  // $200
    allowedActions: ["purchase", "subscribe"], // any money-moving action: transfer, payout, refund, …
    allowedCounterparties: ["etsy.com", "*.shop.example"],
  },
});

const wallet = new AgentWallet(mandate, agent.privateKeyPem);

// Your real payment call goes inside the executor. The guard runs FIRST;
// if the action is out of scope, the executor is never called.
await wallet.spend(
  { type: "purchase", counterparty: "etsy.com", amount: 4500, currency: "USD" },
  async (action) => ({ outcome: "settled", result: await pay(action) }),
);

// A prompt-injected wallet.spend({ counterparty: "attacker.xyz", ... })
// throws GuardViolation — before any money moves.
```

Run `npm run guard-demo` to watch it block live attacker payments.

## Already have a payment tool? Wrap it once.

For MCP / LangChain / function-calling agents, gate an existing tool without restructuring anything:

```ts
import { wrapMcpTool } from "@vantic/sdk";

const guardedPurchase = wrapMcpTool(purchaseTool, {
  wallet,
  toAction: (args) => ({ type: "purchase", counterparty: args.merchant, amount: args.amountCents, currency: args.currency }),
});
// Register `guardedPurchase` instead of `purchaseTool`. A blocked call comes back as a tool
// error the model can read and recover from; the real charge never fires.
```

Framework guides (OpenAI, LangChain, Vercel AI SDK, MCP, raw): **[docs/integrations.md](docs/integrations.md)**.

## What you get

- **Hard spending limits** — per-transaction cap and a rolling budget window, enforced deterministically.
- **Counterparty allowlists** — the agent can only pay who you allow (exact match or wildcard domains).
- **Prompt-injection protection** — the mandate is enforced *outside* the model, so a compromised agent can't spend out of scope.
- **Tamper-proof receipts** — a signed, hash-chained record of every action; verify offline; use as dispute evidence.
- **Standard identity** — agents and owners are W3C `did:key`/`did:web` DIDs, and the owner→agent relationship is a W3C Verifiable Credential.
- **MCP server** — `npx vantic-mcp` exposes verification tools to any MCP host.
- **Zero dependencies** — Node's built-in crypto only. Ed25519 + SHA-256.

## How it works

Two primitives (full spec in [`spec/SPEC.md`](spec/SPEC.md)):

- **Mandate** — a signed statement from an owner authorizing an agent within a scope (budget, limits, counterparties, expiry, revocation).
- **Receipt** — a signed, hash-chained record binding each action to the mandate and its outcome. Tamper-evident.

Everything is deterministic and runs outside the agent's model.

## Use it from an MCP host

```bash
npm run mcp        # or, once published: npx vantic-mcp
```

Exposes stateless verification tools (no private keys): `mandate_authorize`, `mandate_verify_chain`, `mandate_verify_credential`, `mandate_resolve_did`.

## Identity

Agents and owners can be identified by bare keys (`key:<x>`) or by W3C **`did:key`** DIDs — interchangeable, both verify. `generateKeyPair()` returns both. DIDs resolve to standard DID documents offline (`resolveDidKey`), the same key can be published as **`did:web`** (`buildDidWebDocument`), and the owner→agent relationship is a portable **W3C Verifiable Credential** (`issueSponsorCredential` / `verifySponsorCredential`). See `npm run identity-demo`.

## Develop

```bash
cd sdk
npm install
npm test          # 39 tests
npm run demo      # end-to-end walkthrough
```

## Learn more

- **[docs/integrations.md](docs/integrations.md)** — add Vantic to OpenAI / LangChain / Vercel AI SDK / MCP / raw agents.
- **[docs/ap2-and-standards.md](docs/ap2-and-standards.md)** — how Vantic relates to AP2, x402, and the shared "mandate" concept.
- **[docs/agent-spending-security.md](docs/agent-spending-security.md)** — securing agent spending (and why not to roll your own).
- **[spec/SPEC.md](spec/SPEC.md)** — the protocol.

## Status & security

**v0.1 — early, and honest about it.** The code is production-quality (Ed25519 + SHA-256 + canonical JSON; `did:key`/`did:web` + Verifiable Credential identity; zero runtime dependencies), but it is **not yet audited** and the wire format isn't frozen.

- **[`ROADMAP.md`](ROADMAP.md)** — exactly what is and isn't hardened, and the path to v1.0.
- **[`SECURITY.md`](SECURITY.md)** — how to report a vulnerability (please don't open a public issue).
- **[`spec/SPEC.md`](spec/SPEC.md) §8** — threat model and non-goals.

Feedback and PRs welcome. Apache-2.0.
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