Correct! We designed LSIF to be a complement to LSP. LSIF is basically a way to persist language server state, so that LSP queries (e.g. what are the definitions for this symbol?) can be answered without needing an active LSP server running.

Among other things, LSIF enables rich IDE navigations on remote codebases, where’s its much more scalable to perform those queries using indexed data vs. spinning up language servers. Here’s the blog post where we first announced the work we were doing, that led to the creation of LSIF: https://code.visualstudio.com/blogs/2018/12/04/rich-navigati....

Thanks for making that clear.