Lincoln

Lincoln SDK, CLI and MCP server

Give an AI agent (or any program) its own private balance on Robinhood Chain. Hold ETH, dollars and tokenized stocks in the Lincoln privacy pool; send, swap and withdraw with zero-knowledge proofs generated on your machine and submitted by a relayer, so the agent's wallet never appears on chain.

Status: release candidate on Robinhood Chain mainnet (chain 4663): 13 pools (ETH, USDG, USDe, eight stock tokens, PONS and CASHCAT). The contracts are not independently audited yet.

Install

Claude Code (skill + MCP server in one plugin):

/plugin install lincoln --marketplace LincolnProtocol-com/sdk

Then create the wallet (npx @lincolnprotocol/cli init, below) and start Claude Code with LINCOLN_PASSPHRASE set in its environment.

Any MCP client:

export LINCOLN_PASSPHRASE='…'                 # encrypts the agent key; required on mainnet
npx @lincolnprotocol/cli init                 # creates ~/.lincoln/mainnet/agent.json and ~/.lincoln/policy.json
claude mcp add lincoln -e LINCOLN_PASSPHRASE="$LINCOLN_PASSPHRASE" -- npx -y @lincolnprotocol/mcp
codex mcp add lincoln --env LINCOLN_PASSPHRASE="$LINCOLN_PASSPHRASE" -- npx -y @lincolnprotocol/mcp

Just looking? The hosted server is read-only and needs no key or install (pools, fees, relay status, prices, docs):

claude mcp add --transport http lincoln-docs https://mcp.lincolnprotocol.com/mcp

Other harnesses read AGENTS.md; the skill alone is cp -r skills/lincoln ~/.claude/skills/.

CLI

npm i -g @lincolnprotocol/cli
lincoln address       # share the lincoln3: address to fund it privately
lincoln balance
lincoln quote swap 100 usdg nvda
lincoln execute q_…

MCP

{
  "mcpServers": {
    "lincoln": {
      "command": "npx",
      "args": ["-y", "@lincolnprotocol/mcp"],
      "env": { "LINCOLN_PASSPHRASE": "…" }
    }
  }
}

Tools: lincoln_balance, lincoln_address, lincoln_pools, lincoln_policy, lincoln_activity, lincoln_status, lincoln_quote, and lincoln_send / lincoln_swap / lincoln_withdraw / lincoln_deposit, which take a quoteId, never raw amounts.

SDK

import { Lincoln } from '@lincolnprotocol/sdk';

const agent = await Lincoln.open();
console.log(await agent.balances());
const q = await agent.quoteSwap({ from: "usdg", to: "nvda", amount: "100" });
const r = await agent.execute(q.id);            // { txHash, jobId, explorer, message }

How it works

• Wallet. init creates an ordinary key pair. It signs the same sign-in message as the Lincoln web app, and the private wallet seed is derived from that signature, so importing the key into a browser wallet opens the same private balance in the app.
• Spends. Pool state comes from the relay and is checked against the chain (Merkle root and association-set policy) before use. The proof is generated and verified locally, then the relay submits it. Job IDs are kept, so an interrupted spend is followed, never paid twice.
• Circuits. Downloaded once from the Lincoln app, checked against the SHA-256 pins in this package, cached in ~/.lincoln/circuits.
• Network. Pool profiles, swap routes and circuit pins ship with the package; a relay can't redirect funds. Relays, the bridge proxy and circuit files are reached through the Lincoln app's own origin, so third parties don't see the agent's IP.
• Withdrawals to other chains (Base, Arbitrum, Ethereum, Optimism, BSC, Solana; ETH arrives as BNB on BSC and SOL on Solana, USDG stays USDG on Ethereum and Solana, USDT on BSC, USDC elsewhere) go through a single-use Relay deposit address (--receive wbtc|cbbtc|usdc|… picks another token there); withdrawals to Zcash, Bitcoin and Tron go through NEAR Intents. Solana, Zcash, Bitcoin and Tron need --refund <0x…>, a Robinhood Chain address used only if the swap fails. Mainnet only.

Spending policy

~/.lincoln/policy.json is checked at quote time and again before every spend:

{ "perTransactionUsd": 250, "dailyUsd": 1000, "approvalAboveUsd": 100, "allowedRecipients": [], "allowedActions": ["send", "swap", "withdraw", "deposit"] }

Spends above approvalAboveUsd, or of an asset without a USD price, fail with APPROVAL_REQUIRED until the user approves (--approve, or userApproved: true over MCP). Limits are enforced by this software, not by the contracts: anyone with the agent's key can spend its whole balance, so keep only what the agent needs in it.

Rules

Same Terms as the app: no funds linked to crime or sanctions, and not offered in the United States, the United Kingdom or sanctioned regions. The contracts are not independently audited yet.

Develop

npm run build    # tsc -b for all three packages
npm test         # vitest
npm run release  # clean build, tests, then publish sdk, cli and mcp to npm (needs npm login)

Protocol code in packages/sdk/src/core is ported from the Lincoln web app (sdk.ts, relay.ts, fees.ts, state.ts, chain-state.ts, caps.ts, bridge.ts) and must stay byte-compatible with it.