Smart Accounts Kit

forge install metamask/[email protected]

Core Concepts Summary

1. Smart Accounts (ERC-4337)

Three implementation types:

• Hybrid (Implementation.Hybrid) - EOA + passkey signers
• Multisig (Implementation.MultiSig) - Multiple signers with threshold
• Stateless7702 (Implementation.Stateless7702) - EIP-7702 upgraded EOA

2. Delegation Framework (ERC-7710)

Grant permissions from delegator to delegate:

• Scopes - Initial authority (spending limits, function calls)
• Caveats - Restrictions enforced by smart contracts
• Types - Root, open root, redelegation, open redelegation
• Lifecycle - Create → Sign → Store → Redeem

3. Advanced Permissions (ERC-7715)

Request permissions via MetaMask extension:

• Human-readable UI confirmations
• ERC-20 and native token permissions
• Requires MetaMask Flask 13.5.0+
• User must have smart account

Quick Code Examples

Create Smart Account

import { Implementation, toMetaMaskSmartAccount } from '@metamask/smart-accounts-kit'
import { privateKeyToAccount } from 'viem/accounts'

const account = privateKeyToAccount('0x...')

const smartAccount = await toMetaMaskSmartAccount({
  client: publicClient,
  implementation: Implementation.Hybrid,
  deployParams: [account.address, [], [], []],
  deploySalt: '0x',
  signer: { account },
})

Create Delegation

import { createDelegation } from '@metamask/smart-accounts-kit'
import { parseUnits } from 'viem'

const delegation = createDelegation({
  to: delegateAddress,
  from: delegatorSmartAccount.address,
  environment: delegatorSmartAccount.environment,
  scope: {
    type: 'erc20TransferAmount',
    tokenAddress: '0x1c7D4B196Cb0C7B01d743Fbc6116a902379C7238',
    maxAmount: parseUnits('10', 6),
  },
  caveats: [
    { type: 'timestamp', afterThreshold: now, beforeThreshold: expiry },
    { type: 'limitedCalls', limit: 5 },
  ],
})

Sign Delegation

const signature = await smartAccount.signDelegation({ delegation })
const signedDelegation = { ...delegation, signature }

Redeem Delegation

import { createExecution, ExecutionMode } from '@metamask/smart-accounts-kit'
import { DelegationManager } from '@metamask/smart-accounts-kit/contracts'
import { encodeFunctionData, erc20Abi } from 'viem'

const callData = encodeFunctionData({
  abi: erc20Abi,
  args: [recipient, parseUnits('1', 6)],
  functionName: 'transfer',
})

const execution = createExecution({ target: tokenAddress, callData })

const redeemCalldata = DelegationManager.encode.redeemDelegations({
  delegations: [[signedDelegation]],
  modes: [ExecutionMode.SingleDefault],
  executions: [[execution]],
})

// Via smart account
const userOpHash = await bundlerClient.sendUserOperation({
  account: delegateSmartAccount,
  calls: [{ to: delegateSmartAccount.address, data: redeemCalldata }],
})

// Via EOA
const txHash = await delegateWalletClient.sendTransaction({
  to: environment.DelegationManager,
  data: redeemCalldata,
})

Request Advanced Permissions

import { erc7715ProviderActions } from '@metamask/smart-accounts-kit/actions'

const walletClient = createWalletClient({
  transport: custom(window.ethereum),
}).extend(erc7715ProviderActions())

const grantedPermissions = await walletClient.requestExecutionPermissions([
  {
    chainId: chain.id,
    expiry: now + 604800,
    signer: {
      type: 'account',
      data: { address: sessionAccount.address },
    },
    permission: {
      type: 'erc20-token-periodic',
      data: {
        tokenAddress,
        periodAmount: parseUnits('10', 6),
        periodDuration: 86400,
        justification: 'Transfer 10 USDC daily',
      },
    },
    isAdjustmentAllowed: true,
  },
])

Redeem Advanced Permissions

// Smart account
import { erc7710BundlerActions } from '@metamask/smart-accounts-kit/actions'

const bundlerClient = createBundlerClient({
  client: publicClient,
  transport: http(bundlerUrl),
}).extend(erc7710BundlerActions())

const permissionsContext = grantedPermissions[0].context
const delegationManager = grantedPermissions[0].signerMeta.delegationManager

const userOpHash = await bundlerClient.sendUserOperationWithDelegation({
  publicClient,
  account: sessionAccount,
  calls: [
    {
      to: tokenAddress,
      data: calldata,
      permissionsContext,
      delegationManager,
    },
  ],
})

// EOA
import { erc7710WalletActions } from '@metamask/smart-accounts-kit/actions'

const walletClient = createWalletClient({
  account: sessionAccount,
  chain,
  transport: http(),
}).extend(erc7710WalletActions())

const txHash = await walletClient.sendTransactionWithDelegation({
  to: tokenAddress,
  data: calldata,
  permissionsContext,
  delegationManager,
})

Key API Methods

Smart Accounts

• toMetaMaskSmartAccount() - Create smart account
• aggregateSignature() - Combine multisig signatures
• signDelegation() - Sign delegation
• signUserOperation() - Sign user operation
• signMessage() / signTypedData() - Standard signing

Delegations

• createDelegation() - Create delegation with delegate
• createOpenDelegation() - Create open delegation
• createCaveatBuilder() - Build caveats array
• createExecution() - Create execution struct
• redeemDelegations() - Encode redemption calldata
• signDelegation() - Sign with private key
• getSmartAccountsEnvironment() - Resolve environment
• deploySmartAccountsEnvironment() - Deploy contracts
• overrideDeployedEnvironment() - Override environment

Advanced Permissions

• erc7715ProviderActions() - Wallet client extension for requesting
• requestExecutionPermissions() - Request permissions
• erc7710BundlerActions() - Bundler client extension
• sendUserOperationWithDelegation() - Redeem with smart account
• erc7710WalletActions() - Wallet client extension
• sendTransactionWithDelegation() - Redeem with EOA

Supported ERC-7715 Permission Types

ERC-20 Token Permissions

Native Token Permissions

Common Delegation Scopes

Spending Limits

Function Calls

Common Caveat Enforcers

Target & Method

• allowedTargets - Limit callable addresses
• allowedMethods - Limit callable methods
• allowedCalldata - Validate specific calldata
• exactCalldata / exactCalldataBatch - Exact calldata match
• exactExecution / exactExecutionBatch - Exact execution match

Value & Token

• valueLte - Limit native token value
• erc20TransferAmount - Limit ERC-20 amount
• erc20BalanceChange - Validate ERC-20 balance change
• erc721Transfer / erc721BalanceChange - ERC-721 restrictions
• erc1155BalanceChange - ERC-1155 validation

Time & Frequency

• timestamp - Valid time range (seconds)
• blockNumber - Valid block range
• limitedCalls - Limit redemption count
• erc20PeriodTransfer / erc20Streaming - Time-based ERC-20
• nativeTokenPeriodTransfer / nativeTokenStreaming - Time-based native

Security & State

• redeemer - Limit redemption to specific addresses
• id - One-time delegation with ID
• nonce - Bulk revocation via nonce
• deployed - Auto-deploy contract
• ownershipTransfer - Ownership transfer only
• nativeTokenPayment - Require payment
• nativeBalanceChange - Validate native balance
• multiTokenPeriod - Multi-token period limits

Execution Modes

Contract Addresses (v1.3.0)

Core

Critical Rules

Always Required

1. Always use caveats - Never create unrestricted delegations
2. Deploy delegator first - Account must be deployed before redeeming
3. Check smart account status - ERC-7715 requires user has smart account

Behavior

4. Caveats are cumulative - In delegation chains, restrictions stack
5. Function call default - v0.3.0 defaults to NO native token (use valueLte)
6. Batch mode caveat - No compatible caveat enforcers available

Requirements

7. ERC-7715 requirements - MetaMask Flask 13.5.0+, smart account
8. Multisig threshold - Need at least threshold signers
9. 7702 upgrade - Stateless7702 requires EIP-7702 upgrade first

Common Patterns

Pattern 1: ERC-20 with Time Limit

const delegation = createDelegation({
  to: delegate,
  from: delegator,
  environment,
  scope: {
    type: 'erc20TransferAmount',
    tokenAddress,
    maxAmount: parseUnits('100', 6),
  },
  caveats: [
    { type: 'timestamp', afterThreshold: now, beforeThreshold: expiry },
    { type: 'limitedCalls', limit: 10 },
    { type: 'redeemer', redeemers: [delegate] },
  ],
})

Pattern 2: Function Call with Value

const delegation = createDelegation({
  to: delegate,
  from: delegator,
  environment,
  scope: {
    type: 'functionCall',
    targets: [contractAddress],
    selectors: ['transfer(address,uint256)'],
    valueLte: { maxValue: parseEther('0.1') },
  },
  caveats: [{ type: 'allowedMethods', selectors: ['transfer(address,uint256)'] }],
})

Pattern 3: Periodic Native Token

const delegation = createDelegation({
  to: delegate,
  from: delegator,
  environment,
  scope: {
    type: 'nativeTokenPeriodTransfer',
    periodAmount: parseEther('0.01'),
    periodDuration: 86400,
    startDate: now,
  },
})

Pattern 4: Redelegation Chain

// Alice → Bob (100 USDC)
const aliceToBob = createDelegation({
  to: bob,
  from: alice,
  environment,
  scope: { type: 'erc20TransferAmount', tokenAddress, maxAmount: parseUnits('100', 6) },
})

// Bob → Carol (50 USDC, subset of authority)
const bobToCarol = createDelegation({
  to: carol,
  from: bob,
  environment,
  scope: { type: 'erc20TransferAmount', tokenAddress, maxAmount: parseUnits('50', 6) },
  parentDelegation: aliceToBob,
  caveats: [{ type: 'timestamp', afterThreshold: now, beforeThreshold: expiry }],
})

Troubleshooting Quick Fixes

Resources

• NPM: @metamask/smart-accounts-kit
• Contracts: metamask/[email protected]
• ERC Standards: ERC-4337, ERC-7710, ERC-7715, ERC-7579
• MetaMask Flask: https://metamask.io/flask

Version Info

• Toolkit: 0.3.0
• Delegation Framework: 1.3.0
• Breaking Change: Function call scope defaults to no native token transfer

For detailed documentation, see the reference files in the /references directory.