Comprehensive Security Assessment

CAP-01: Decentralized Governance via Renounced Ownership

Description: The contract was engineered for full decentralization post-launch. After the initial setup of the investment plans, the contract ownership has been **irrevocably renounced** by transferring it to the zero address (`0x000...000`). This action is permanent and guarantees that no single entity, including the original developers, retains privileged control over the contract's core functions.

// Initial owner, set at deployment time.
address public owner;

// Function to permanently renounce ownership.
function renounceOwnership() public {
    require(msg.sender == owner, "Not owner");
    owner = address(0);
}

// Once renounced, this modifier will fail forever,
// permanently disabling the functions that use it.
modifier onlyOwner() {
    require(msg.sender == owner, "Ownership has been renounced");
    _;
}

// This emergency withdrawal function becomes UNUSABLE
// after renunciation, as no one can meet the 'require' condition.
function emergencyWithdraw() external onlyOwner {
    uint256 balance = USDT.balanceOf(address(this));
    USDT.transfer(owner, balance);
}

Security Assessment: This is the most critical security feature of the contract. By renouncing ownership, administrative functions like `emergencyWithdraw`, `withdrawBNB`, and `updatePlan` become permanently inoperable. This transforms the contract into an autonomous and immutable protocol. It completely eliminates the risk of malicious administrative actions, "rug pulls," or unauthorized fund withdrawals by a central entity. All funds within the contract are governed solely by the public, unchangeable rules of the code and can only be accessed by users according to their investment terms. **This represents the gold standard for trustless DeFi applications, ensuring no backdoors exist.**

// Plan structure defined within the contract.
struct Plan {
    uint256 minAmount;
    uint256 maxAmount;
    uint256 duration;
    uint256 dailyReturn; // In basis points.
}

// Deposit function with strict validation.
function deposit(uint256 amount, uint256 planId, address referrer) external payable {
    // 1. Validates the plan exists and the amount is within limits.
    require(planId >= 1 && planId <= 5, "Invalid plan");
    require(amount >= plans[planId].minAmount && amount <= plans[planId].maxAmount, "Invalid amount");
    
    // 2. Securely transfers USDT from the user to this contract.
    require(USDT.transferFrom(msg.sender, address(this), amount), "USDT transfer failed");
    
    // 3. Creates an immutable record of the investment.
    Investment memory newInvestment = Investment({ /* ... */ });
    userInvestments[msg.sender].push(newInvestment);
    
    // 4. Updates global on-chain statistics.
    if (userStats[msg.sender].investmentCount == 0) {
        totalUsers++;
    }
    totalDeposited += amount;
    
    emit InvestmentCreated(msg.sender, planId, amount);
}

// Public state variables for global statistics.
uint256 public totalUsers;
uint256 public totalDeposited;
uint256 public totalWithdrawn;

// Events providing a real-time, on-chain activity log.
event InvestmentCreated(address indexed user, uint256 planId, uint256 amount);
event WithdrawalProcessed(address indexed user, uint256 amount);
event PrincipalClaimed(address indexed user, uint256 investmentId, uint256 amount);
event ReferralPaid(address indexed referrer, address indexed user, uint256 level, uint256 amount);

// View function to retrieve global stats.
function getGlobalStats() external view returns (uint256, uint256, uint256) {
    return (totalUsers, totalDeposited, totalWithdrawn);
}