Vyper developer banteg just shipped a tool designed to take the terror out of upgrading legacy smart contracts.
The tool is called vyupgrade, and it automatically rewrites legacy Vyper smart contracts to be compatible with modern versions of the language, then runs a battery of safety checks to make sure the updated code behaves identically to the original.
How vyupgrade actually works
Developers run a single command, uvx vyupgrade contracts/, and the tool handles the rest. Point it at a folder of old contracts and let it do the heavy lifting.
Under the hood, vyupgrade compares compilation outputs between the original and rewritten versions of each contract. It checks Application Binary Interfaces, which are essentially the rules governing how external software talks to a smart contract. It verifies method identifiers. It inspects storage layouts, which dictate how data is organized on-chain.
