SBTB 2019: Ólafur Geirsson, Metals - building rich IDE features beyond the Language Server Protocol

ai.bythebay.io Nov 2025, Oakland, full-stack AI conference The Language Server Protocol (LSP) has enabled hundreds of programming languages to support rich code editing features such as code completions in dozens of text editors including VS Code, Vim, Emacs and Sublime Text as well as the next generation of web IDEs. While LSP has been successful at gaining industry adoption, users coming from IDEs such as IntelliJ or XCode quickly observe that a lot of nice features may be missing from the protocol. In this talk, you will learn what steps Metals, a Scala language server, is taking to bridge the gap between IDEs and LSP. We demonstrate how Metals uses a suite of additional protocols including the Debug Adapter Protocol, Build Server Protocol and Tree View Protocol to support run/test/debug, package explorers, build explorers and more. Join us as we build a bright future for cross-language, cross-platform and cross-editor tooling! Ólafur Geirsson Twitter Ólafur Páll works on Scala developer tooling at Twitter. He is the author of several open source projects including Scalafmt, Scalafix and Metals.