Explore a comprehensive conference talk on Metals, a rich code editing tool for Scala in various text editors. Dive into the intricacies of Scala editor usage, global editor functionality, and two in-depth case studies focusing on diagnostics and completions. Learn about different approaches to diagnostics, the Build Server Protocol, and the challenges of slow feedback. Discover the nuances of completions, including presentation compiler usage, pattern matching, and performance optimization techniques. Gain insights into compiler plugins, blackbox macros, and the differences between blackbox and whitebox macros. Understand the importance of cancellation in editor performance and explore the wide range of features Metals offers. Compare its implementation across Visual Studio Code, Emacs, and Sublime Text, and get a glimpse of future developments in Scala code editing.