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What is the EVC?

The Ethereum Vault Connector (EVC) is Mewler’s system for enabling advanced transaction patterns. It allows you to:
  • Execute multiple operations atomically
  • Use sub-accounts for position isolation
  • Delegate permissions to operators
  • Temporarily violate limits (with deferred checks)

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Batching Operations

The EVC allows you to combine multiple operations into a single atomic transaction. This is useful for:
  • Opening leveraged positions
  • Repaying debt and withdrawing collateral in one step
  • Complex DeFi strategies requiring multiple steps

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Example: Opening a Leveraged Position

Without EVC, you’d need multiple transactions:
  1. Deposit collateral
  2. Borrow asset
  3. Swap borrowed asset for more collateral
  4. Deposit new collateral
With EVC, all steps happen atomically in one transaction.

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Sub-Accounts

Each wallet address can have up to 256 sub-accounts. Sub-accounts are virtual accounts identified by a sub-account ID (0-255).

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Use Cases

Position Isolation: Separate trading strategies or risk profiles: 
Main Account (ID: 0)
├── Sub-account 1: Conservative strategy
├── Sub-account 2: Aggressive leverage
└── Sub-account 3: Experimental positions
Risk Management: Isolate risky positions from your main account to prevent cross-contamination. Testing: Use sub-accounts to test strategies without affecting your main position.

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Sub-Account Addressing

Sub-accounts are addressed using the format: 
address:subAccountId
For example:
  • 0x123...abc:0 - Main account
  • 0x123...abc:1 - Sub-account 1
  • 0x123...abc:42 - Sub-account 42

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Operators

Operators are addresses you trust to execute transactions on your behalf. This enables:
  • Automated strategies
  • Bot trading
  • DeFi protocol integrations
  • Smart contract automation

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Setting an Operator

You can grant operator permissions to:
  • Specific addresses
  • Smart contracts
  • Your own contracts for automation
Security Note: Only grant operator permissions to addresses you fully trust, as they can execute transactions on your behalf.

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Deferred Checks

The EVC implements deferred checks, which allow operations to temporarily violate limits as long as the final state is valid.

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How It Works

  1. Start Transaction: Begin a batch of operations
  2. Intermediate States: Some operations might temporarily violate limits (e.g., health score drops below 1.0)
  3. Final State: All limits must be satisfied at the end
  4. Atomic Execution: Either all operations succeed or all fail

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Example

You want to:
  1. Withdraw collateral (would make health score < 1.0)
  2. Repay debt (brings health score back > 1.0)
Without deferred checks, step 1 would fail. With deferred checks, both steps execute atomically, and the final state (after repayment) is valid.

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EVC Functions

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Batch Operations

function batch(bytes[] calldata calls) external;
Execute multiple operations in a single transaction.

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Sub-Account Operations

Operations can specify a sub-account ID to target a specific sub-account.

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Operator Delegation

function setOperator(address operator, bool enabled) external;
Enable or disable an operator for your account.

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Best Practices

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Batching

  • Group related operations together
  • Consider gas costs (batching can save gas)
  • Ensure final state is always valid

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Sub-Accounts

  • Use sub-accounts to isolate different strategies
  • Don’t create more sub-accounts than necessary
  • Document which sub-account is for what purpose

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Operators

  • Only grant permissions to trusted addresses
  • Regularly review and revoke unused operators
  • Use time-limited permissions when possible

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References

For more technical details: