I used to work on the team that built this tool, and I've been eagerly awaiting its open source release. Of course, I think it's fantastic :)

There's so much interesting work being done on static analysis in Go (semgrep, ruleguard, etc), but I haven't seen similarly powerful refactoring tools. Gopatch is one approach to building a refactoring power tool - I'm excited to start using it, but I hope that it also inspires people (and companies!) to build even more capable tools.