Solidity Upgrades Contents - Proxy Patterns Overview - Upgrade Restrictions Between Major Versions (v4 → v5) - Writing Upgradeable Contracts - Hardhat Upgrades Workflow - Foundry Upgrades Workflow - Handling Upgrade Validation Issues - Upgrade Safety Checklist Proxy Patterns Overview | Pattern | Upgrade logic lives in | Best for | |---------|----------------------|----------| | UUPS ( ) | Implementation contract (override ) | Most projects — lighter proxy, lower deploy gas | | Transparent | Separate contract | When admin/user call separation is critical — admin cannot accidentally call implem…