I have checked that this feature is not already implemented

• This feature does not exist

Use case

I would make it possible to use a per-project configuration with eglot on Emacs using a default way to do that via .dir-locals.el.

Description

I have been trying to set up Ruby LSP via eglot with a per-project settings (using StandardRB addon) via .dir-locals.el, as described here. However, the formatting did not work as the server kept telling me it does not support :documentFormattingProvider. I found that this is because eglot sends workspace/didChangeConfiguration after having initialized the language server, but Ruby LSP does not support such reconfiguration.

I found #205 where this was considered, but dropped, because it was not needed for VSCode.

Implementation

I think with some guidance, I can implement it. It seems that what's mainly needed in response to this message is to update the global state and send new capabilities to the client. Although there might be some other details I'm not able to predict right now.