Blockchain & Web3 Development Smart Contract Development (Solidity) Contract Structure Security Patterns - Checks-Effects-Interactions: Validate → update state → external calls - Reentrancy guard: Use OpenZeppelin or - Access control: , , or custom modifiers - Integer safety: Solidity 0.8+ has built-in overflow checks - Pull over push: Let users withdraw rather than sending funds Common Vulnerabilities | Vulnerability | Prevention | |--------------|------------| | Reentrancy | modifier, CEI pattern | | Front-running | Commit-reveal schemes, flashbot protection | | Oracle manipulation | Use Ch…