wagmi v2 broke everything. If you've tried migrating a real DeFi frontend from wagmi v1 to v2, you know exactly what I mean.

Every hook was renamed. The provider component changed. Connectors went from classes to factory functions. TanStack Query params moved into a nested query:{} object. configureChains was removed entirely. The official migration guide is 4,000+ words long.

I built a codemod that automates 85% of this migration deterministically — with zero false positives — and leaves clear AI-ready TODO comments for the remaining 15%. Here's exactly how I did it, what worked, what didn't, and the real numbers from running it against the official wagmi v1 examples repo.

The Problem

wagmi v2 is a ground-up rewrite built around two new primitives:

Viem instead of ethers.js

TanStack Query instead of internal state management

This meant every single hook had a breaking change. Not just renames — the entire API contract changed. useContractWrite in v1 accepted the contract config at the hook level.…