@b402ai/sdk

Private on-chain execution for agents on Base.

One private key. Anonymous smart wallet. Gasless transactions. ZK-proven privacy.

Install

npm install @b402ai/sdk

Quick Start

import { B402 } from '@b402ai/sdk'

const b402 = new B402({ privateKey: process.env.WORKER_PRIVATE_KEY })

// Shield — move USDC into privacy pool (breaks on-chain link)
await b402.shield({ token: 'USDC', amount: '100' })

// Private swap — fully private, funded from pool
await b402.privateSwap({ from: 'USDC', to: 'WETH', amount: '10' })

// Earn yield — deposit into Morpho vault
await b402.lend({ token: 'USDC', amount: '50', vault: 'steakhouse' })

// Check everything
const status = await b402.status()

The only required config is privateKey. The SDK derives an anonymous smart wallet, and the b402 facilitator sponsors all gas.

How It Works

Your Key → Incognito EOA → Anonymous Smart Wallet → DeFi
              (derived)        (gasless, untraceable)

Shield deposits tokens into the Railgun privacy pool. Unshield generates a client-side ZK proof and moves tokens to your anonymous smart wallet — no on-chain link between source and destination. From there, lend, swap, and transact — all gasless through the facilitator.

Private operations (privateSwap, privateLend, etc.) go a step further: they unshield directly into a RelayAdapt contract, execute DeFi calls, and shield the output — all in one atomic transaction. On-chain observers see the RelayAdapt contract, never your wallet.

Configuration

const b402 = new B402({
  privateKey: '0x...',              // Required. Derives anonymous wallet.
  zeroXApiKey: '...',               // Optional. Required for swap() only.
  rpcUrl: 'https://...',            // Optional. Default: public Base RPC.
  facilitatorUrl: 'https://...',    // Optional. Default: production facilitator.
  onProgress: (event) => { ... },   // Optional. Step-by-step progress updates.
})

API

Privacy Pool

b402.shield({ token, amount }) — Enter privacy pool

Moves tokens from the smart wallet into the Railgun privacy pool. After shielding, the funding source is untraceable.

const { txHash, indexed } = await b402.shield({ token: 'USDC', amount: '100' })

b402.shieldFromEOA({ token, amount }) — Shield from master EOA

Gasless shield directly from your master EOA using EIP-3009 transferWithAuthorization. Useful for bootstrapping.

await b402.shieldFromEOA({ token: 'USDC', amount: '100' })

b402.unshield({ token, amount }) — Exit privacy pool

Generates a ZK proof (Groth16) client-side and withdraws to the anonymous smart wallet. Supports partial unshields with automatic change note management.

const { txHash, proofTimeSeconds } = await b402.unshield({ token: 'USDC', amount: '50' })
// Pass amount: 'all' to drain all UTXOs

b402.consolidate({ token? }) — Merge UTXOs

Merges fragmented UTXOs into one. Auto-runs before private operations when needed.

Yield (Morpho Vaults)

b402.lend({ token, amount, vault? }) — Deposit into vault

await b402.lend({ token: 'USDC', amount: '100', vault: 'steakhouse' })

| Vault | Name | APY | |-------|------|-----| | steakhouse | Steakhouse USDC | 3-4% | | moonwell | Moonwell Flagship USDC | 3-4% | | gauntlet | Gauntlet USDC Prime | 3-4% | | steakhouse-hy | Steakhouse High Yield | 3-4% |

b402.redeem({ vault?, shares? }) — Withdraw from vault

const { assetsReceived } = await b402.redeem({ vault: 'steakhouse' })

b402.rebalance(minApyDiff?) — Move to highest-yield source

Compares all yield sources (Morpho vaults + Aerodrome LP) and moves capital if APY difference exceeds threshold.

Swaps

b402.swap({ from, to, amount }) — Token swap via 0x

Requires zeroXApiKey in config.

await b402.swap({ from: 'USDC', to: 'WETH', amount: '10' })

Aerodrome LP

b402.addLiquidity({ pool?, amount }) — Add LP

Single-token input (USDC) — SDK splits and swaps half automatically. LP tokens are staked in gauge to earn AERO.

await b402.addLiquidity({ pool: 'weth-usdc', amount: '50' })

b402.removeLiquidity({ pool? }) — Remove LP + claim rewards

const { amountWETH, amountUSDC } = await b402.removeLiquidity({ pool: 'weth-usdc' })

b402.claimRewards({ pool? }) — Claim AERO only

Private Operations (via RelayAdapt)

All private operations execute atomically through Railgun's RelayAdapt contract. On-chain observers see the contract, never your wallet.

b402.privateSwap({ from, to, amount }) — Private token swap

await b402.privateSwap({ from: 'USDC', to: 'WETH', amount: '0.5' })

b402.privateLend({ token?, amount, vault? }) — Private vault deposit

await b402.privateLend({ token: 'USDC', amount: '0.5', vault: 'steakhouse' })

b402.privateRedeem({ vault? }) — Private vault withdrawal

Perpetuals

b402.synfuturesTrade({ instrument, side, notional, margin }) — Open perp (SynFutures V3)

await b402.synfuturesTrade({ instrument: 'BTC', side: 'long', notional: '20', margin: '10' })

b402.synfuturesClose({ instrument }) — Close perp position

b402.privateSynfuturesTrade(...) — Open perp from privacy pool

Speed Markets (Thales)

b402.speedMarket({ asset, direction, amount, duration? }) — Binary option

await b402.speedMarket({ asset: 'ETH', direction: 'up', amount: '10', duration: '10m' })

b402.privateSpeedMarket(...) — Binary option from privacy pool

General

b402.transact(calls) — Arbitrary smart contract calls

Execute any calldata through the anonymous smart wallet. Gasless.

await b402.transact([{ to: '0x...', value: '0', data: '0x...' }])

b402.status() — Wallet state

const s = await b402.status()
// s.smartWallet       — anonymous wallet address
// s.balances          — [{ token: 'USDC', balance: '50.0' }]
// s.shieldedBalances  — [{ token: 'USDC', balance: '25.0' }]
// s.positions         — [{ vault: 'steakhouse', assets: '100.5 USDC', apyEstimate: '3.5%' }]
// s.lpPositions       — [{ pool: 'weth-usdc', usdValue: '500', apyEstimate: '7.6%' }]

Static Helpers

B402.vaults          // available yield vaults
B402.tokens          // supported tokens (USDC, WETH, DAI, AERO)
B402.pools           // Aerodrome LP pools
B402.perpMarkets     // SynFutures instruments
B402.speedMarketAssets // ['ETH', 'BTC']

Supported Tokens

| Token | Address | |-------|---------| | USDC | 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 | | WETH | 0x4200000000000000000000000000000000000006 | | DAI | 0x50c5725949A6F0c72E6C4a641F24049A917DB0Cb | | AERO | 0x940181a94A35A4569E4529A3CDfB74e38FD98631 |

For Agents

Every method takes plain strings and returns plain objects. No ABI encoding, no gas estimation, no nonce management.

const b402 = new B402({ privateKey: agentKey })
await b402.shield({ token: 'USDC', amount: '1000' })
await b402.privateLend({ token: 'USDC', amount: '1000', vault: 'steakhouse' })

For tool-calling agents, each method maps directly to a tool:

{
  "name": "b402_shield",
  "description": "Move tokens into Railgun privacy pool",
  "parameters": {
    "token": { "type": "string", "enum": ["USDC", "WETH", "DAI", "AERO"] },
    "amount": { "type": "string" }
  }
}

Error Handling

All methods throw on failure:

try {
  await b402.lend({ token: 'USDC', amount: '100' })
} catch (err) {
  console.error(err.message)
}

| Error | Cause | |-------|-------| | privateKey or signer is required | Missing private key or signer | | zeroXApiKey required for swaps | Called swap() without API key | | Unknown token: X | Token not supported | | No shares in vault | Called redeem() on empty vault | | No shielded balance | Called unshield/private op without shielding first | | Facilitator verify failed | Invalid UserOp or facilitator issue |

Networks

| Chain | ID | Railgun Contract | Supported Operations | |-------|-----|-----------------|---------------------| | Base | 8453 | 0x2611...4fbE85 | All (shield, unshield, swap, lend, LP, perps, private ops) | | BSC | 56 | 0x9dB0...b04fE | Privacy layer (shield, unshield, transact) |

Default: Base. Set B402_CHAIN=bsc env var for BSC.

All operations use real tokens.

License

MIT