Streaming Fee Module — Index Lab

Description

AUM-based streaming fee implementation following the Index Coop pattern. Continuously accrues fees via index token inflation directed to a fee recipient. Supports configurable fee rates with governance-controlled caps and a timelock on fee changes to protect index holders.

Details

Category: contracts
Files: 10
Chains: Ethereum, Arbitrum, Base, Optimism

Solidity ^0.8.24 OpenZeppelin v5 Foundry Ethereum Arbitrum Base Optimism

Continuous streaming fee accrual
Inflation-to-recipient pattern (Index Coop style)
Configurable annual fee rate (basis points)
Immutable fee cap (max 5% annually)
48-hour timelock on fee rate changes
Fee recipient management with 2-step transfer
Pure calculation functions for off-chain preview
Composable — attaches to any index token
Full NatSpec documentation
Comprehensive Foundry test suite

streaming-fee-module.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

/// @title Streaming Fee Module
/// @notice AUM fee implementation (inflation-to-recipient, Index Coop pattern).
contract StreamingFeeModule {
    address public immutable owner;
    uint256 public constant VERSION = 1;

    event Initialized(address indexed deployer);

    constructor() {
        owner = msg.sender;
        emit Initialized(msg.sender);
    }

    // ... full implementation in purchased package
}