Well, I couldn't let it go, so I found a way 馃槂
github.com/Shopify/ruby...
Motivation
Zed doesn't support snippet syntax ($0) in document/onTypeFormatting responses, nor is it possible for its Ruby extension to implement it. Because the cursor position isn't right...
It's disappointing that auto-insertion of "end" after typing "def foo<enter>" isn't implementable via LSP "on type formatting".
Ruby LSP makes it work with VSCode, but it relies on snippet syntax to bring the cursor back inside the method body, which isn't in the spec. So, it doesn't work in Zed.