Viem Sweep

Overview

This skill provides implementation patterns for advanced transaction strategies using viem v2. It covers methods for moving assets from multiple sources to a destination, ranging from simple private key transfers to advanced gas-optimized and signature-based patterns.

Strategy Selection Guide

Choose the appropriate strategy based on your requirements and infrastructure:

1. Legacy Strategy (Direct Transfer)

Best for: General use case with private keys.

• Pros: Works with any ERC20 token; simple logic.
• Cons: High gas cost (requires ETH on every source account); management of dust ETH.
• Mechanism: Admin funds source -> Source sends token.

2. Factory Strategy (CREATE2)

Best for: High-volume deposit addresses (e.g., exchanges).

• Pros: Lowest gas cost; clean address management; no private keys needed (just salt).
• Cons: Requires initial setup (factory contract); addresses must be generated by factory.
• Mechanism: Predict address -> Deploy (if needed) & Flush in one tx.

3. Permit Strategy (EIP-2612)

Best for: Gasless user experiences with compatible tokens (e.g., UNI, DAI).

• Pros: Gasless for user (relayer pays); single batch transaction.
• Cons: Token MUST support EIP-2612; requires private key signature.
• Mechanism: User signs Permit -> Admin submits batch.

4. Auth Strategy (EIP-3009)

Best for: USDC and other tokens supporting TransferWithAuthorization.

• Pros: Gasless for user; single batch transaction; handles non-sequential nonces (USDC).
• Cons: Token MUST support EIP-3009.
• Mechanism: User signs Authorization -> Admin submits batch.

5. EIP-7702 Strategy (Delegation)

Best for: Future-proofing and "upgrading" EOAs to smart contracts temporarily.

• Pros: Allows EOAs to act as contracts (batching, recovery, sponsored gas) without permanent migration.
• Cons: Requires chain support (Prague hardfork+).
• Mechanism: User signs delegation -> Admin executes tx with auth list.

Implementation Details

For detailed code examples, ABI snippets, and deep-dive explanations of each strategy, refer to the Strategies Reference. The underlying Solidity contract logic can be found in the Contracts Reference.

Usage

When implementing these strategies, ensure you have:

1. Viem v2 installed.
2. Access to a PublicClient (for reads/simulation) and WalletClient (for signing/sending).
3. Relevant ABI definitions (standard ERC20, or your specific Factory/Sweeper contracts).

To request specific implementation details, ask:

• "How do I implement a factory sweep with viem?"
• "Show me the EIP-7702 signing flow."
• "What is the difference between Permit and Auth strategies?"