Account Abstraction (ERC-4337): How a Smart Contract Wallet Differs From a Regular One, and What It Costs You

ERC-4337 lets code, not a fixed keypair, decide what counts as a valid transaction, which is what makes gas sponsorship, session keys, social recovery and batching possible. This reference explains each mechanism against the primary specifications and then sets out the new trust assumptions it introduces, including bundler dependence, paymaster griefing, upgradeable wallet logic and EIP-7702 delegation phishing.