Delegation

Delegation is the ability for a MetaMask smart account to grant permission to another smart account or externally owned account (EOA) to perform specific executions on its behalf. The account that grants the permission is called the delegator account, while the account that receives the permission is called the delegate account.

The MetaMask Delegation Toolkit follows the ERC-7710 standard for smart contract delegation. In addition, users can use caveat enforcers to apply rules and restrictions to delegations. For example: Alice delegates the ability to spend her USDC to Bob, limiting the amount to 100 USDC.

Delegation lifecycle

The delegation lifecycle is as follows:

1. Create a delegation - The delegator account creates a delegation, applying caveats which specify conditions under which the delegation can be redeemed. The delegator signs the delegation.

2. Store the delegation - A dapp can store the delegation, enabling retrieval for future redemption.

3. Redeem the delegation - The delegate (the account being granted the permission) redeems the delegation via the Delegation Manager, which verifies that the delegated authority is valid in order to perform the execution.

See how to perform executions on a smart account's behalf to get started with the delegation lifecycle.

Delegation types

You can create the following delegation types:

• Root delegation - A root delegation is when a delegator delegates their own authority away, as opposed to redelegating permissions they received from a previous delegation. In a chain of delegations, the first delegation is the root delegation. For example, Alice delegates the ability to spend her USDC to Bob, limiting the amount to 100 USDC.

  Use createDelegation to create a root delegation.

• Open root delegation - An open root delegation is a root delegation that doesn't specify a delegate. This means that any account can redeem the delegation. For example, Alice delegates the ability to spend 100 of her USDC to anyone.

  You must create open root delegations carefully, to ensure that they are not misused. Use createOpenDelegation to create an open root delegation.

• Redelegation - A delegate can redelegate permissions that have been granted to them, creating a chain of delegations across trusted parties. For example, Alice delegates the ability to spend 100 of her USDC to Bob. Bob redelegates the ability to spend 50 of Alice's 100 USDC to Carol.

  Use createDelegation to create a redelegation.

• Open redelegation - An open redelegation is a redelegation that doesn't specify a delegate. This means that any account can redeem the redelegation. For example, Alice delegates the ability to spend 100 of her USDC to Bob. Bob redelegates the ability to spend 50 of Alice's 100 USDC to anyone.

  As with open root delegations, you must create open redelegations carefully, to ensure that they are not misused. Use createOpenDelegation to create an open redelegation.

Delegation Framework

The MetaMask Delegation Toolkit includes the Delegation Framework, which is a set of comprehensively audited smart contracts that collectively handle delegator account creation, the delegation lifecycle, and caveat enforcement. It consists of the following components:

• Delegator Core - Delegator Core contains the logic for the ERC-4337 compliant delegator accounts. It defines the interface needed for the Delegation Manager to invoke executions on behalf of the accounts.

• Delegator account implementations - Delegator accounts are smart accounts, and there are multiple smart account implementations, with differing signature schemes used to manage the underlying account.

• Delegation Manager - The Delegation Manager validates delegations and triggers executions on behalf of the delegator, ensuring tasks are executed accurately and securely.

  When you redeem a delegation using redeemDelegations, the Delegation Manager performs the following steps. It processes a single step for all redemptions before proceeding to the next one:

  1. Validates the input data by ensuring the lengths of delegations, modes, and executions match.
  2. Decodes and validates the delegation, checking that the caller is the delegate and that there are no empty signatures.
  3. Verifies delegation signatures, ensuring validity using ECDSA (for EOAs) or isValidSignature (for contracts).
  4. Validates the delegation chain's authority and ensures delegations are not disabled.
  5. Executes the beforeHook for each caveat in the delegation, passing relevant data (terms, arguments, mode, execution calldata, and delegationHash) to the caveat enforcer.
  6. Calls executeFromExecutor to perform the delegation's execution, either by the delegator or the caller for self-authorized executions.
  7. Executes the afterHook for each caveat, similar to the beforeHook, passing required data to enforce post-execution conditions.
  8. Emits RedeemedDelegation events for each delegation that was successfully redeemed.

• Caveat enforcers - Caveat enforcers manage rules and restrictions for delegations, providing fine-tuned control over delegated executions.

Delegation flow

This diagram shows how a delegation is created and redeemed with the Delegation Manager. The Delegation Manager is responsible for validating the signature of the delegation and the caveat enforcers. If everything is correct, it allows a delegate to execute an action on behalf of the delegator.

Learn more about the caveat enforcer hooks in the Caveat enforcers section.

Execution modes

When redeeming a delegation using redeemDelegations, you must pass an execution mode for each delegation chain you pass to the method. The Delegation Toolkit supports the following execution modes, based on ERC-7579:

Execution mode	Number of delegation chains passed to redeemDelegations	Processing method	Does user operation continue execution if redemption reverts?
SINGLE_DEFAULT_MODE	One	Sequential	No
SINGLE_TRY_MODE	One	Sequential	Yes
BATCH_DEFAULT_MODE	Multiple	Interleaved	No
BATCH_TRY_MODE	Multiple	Interleaved	Yes

Sequential processing

In SINGLE modes, processing is sequential:

1. For each delegation in the chain, all caveats' before hooks are called.
2. The single redeemed action is executed.
3. For each delegation in the chain, all caveats' after hooks are called.

Interleaved processing

In BATCH modes, processing is interleaved:

1. For each chain in the batch, and each delegation in the chain, all caveats' before hooks are called.
2. Each redeemed action is executed.
3. For each chain in the batch, and each delegation in the chain, all caveats' after hooks are called.

BATCH mode allows for powerful use cases, but the Delegation Framework currently does not include any BATCH compatible caveat enforcers.