🥩 Time-Locked Staking Protocol

A decentralized yield farming protocol enabling time-locked asset staking with native Ether rewards.

This system replaces centralized scheduling (Cron jobs) with on-chain timekeeping, creating a trustless mechanism for asset maturity. It is engineered with a "Safety-First" architecture, utilizing defensive coding patterns to handle non-standard ERC20 tokens and potential interactions with malicious contracts.

🏗 Architecture & Design Decisions

1. Trustless Scheduling

• EVM Time Management:
  • Logic relies purely on block.timestamp state deltas to determine reward eligibility (timeElapsed < stakingPeriod).
  • Benefit: Removes dependency on external Keepers or Oracle updates for reward distribution, ensuring the protocol is self-contained and censorship-resistant.

2. Defensive Engineering

• SafeERC20 Integration:
  • Uses OpenZeppelin's SafeERC20 wrapper for all token transfers. This ensures compatibility with non-compliant tokens (like USDT) that do not return a boolean value on transfer, preventing silent failures.
• Hostile Actor Protection:
  • The claimRewards function is protected by ReentrancyGuard and strictly validates the return value of the low-level ETH .call.
  • Explicit Failure Handling: If the recipient cannot accept ETH (e.g., a contract without a receive() function), the transaction reverts securely with TransferFailed rather than leaving the system in an inconsistent state.

3. Advanced QA Strategy (Foundry)

The test suite goes beyond happy paths to achieve 100% Branch Coverage:

• Hostile Simulation: Implemented a RejectEther mock contract in the test suite specifically to force low-level call failures, verifying that the protocol correctly reverts when interactions fail.
• Time Travel Fuzzing: Leverages vm.warp() to simulate weeks of staking duration in milliseconds, validating logic across varied timeframes without mainnet waiting periods.

🛠 Tech Stack

• Core: Solidity ^0.8.24
• Libraries: OpenZeppelin (SafeERC20, Ownable, ReentrancyGuard)
• Testing: Foundry (Fuzzing, Mocking, Time Manipulation)

📝 Contract Interface

The protocol exposes a simple state-machine interface for stakers:

// Core Interaction
function depositTokens(uint256 amount) external;
function withdrawTokens() external;
function claimRewards() external; // Distributes ETH based on time deltas