ERC721A Upgradeable

ERC721A-Upgradeable (v4.3.0) is the upgradeable variant of ERC721A, a gas-efficient ERC721 implementation for batch minting popularized by NFTs. It uses the diamond storage pattern (EIP-2535) for storage layout compatibility across upgrades. Major version changes break storage (e.g., 3.x to 4.x). Requires OpenZeppelin's initializer pattern and a separate initializerERC721A modifier. Release cadence follows ERC721A main package. Differentiators: batch minting to save gas, upgradeable-friendly storage, explicit tooling recommendations (OpenZeppelin Upgrades Plugins). No peer dependencies beyond Solidity ^0.8.4.