I know lexical coloring is something that should be done on the client. However as this information is fully declarative (TextMate language grammars) we could serve the initial configuration from a language server instead of putting it into the extension json.

The reason is that I would like to define and package one language server and use it in many different editors as is. I.e. without the need to do some editor specific plumbing for every editor. Today only VSCode understands this protocol, but we should try to make it more widely used in order to leverage its full potential. I.e. we are working on a client for Che and on a server side implementation with Xtext.

For servers that only target vscode It could be simply ignored and turned off through the server capabilities.