From the link:
“If you've used Metals before, you'll notice that when you first open up a project, you'll be prompted to Import Your Build. What does this mean? The first time this happens, it means that Metals detects that you have no .bloop directory, and therefore you need to import your build. When using sbt this means that Metals actually adds the sbt-bloop plugin to your build in project/metals.sbt. It then issues an sbt bloopInstall command which will dump out your build definition for all of your modules into JSON files, which you can see if you open up your .bloop directory in your workspace.”
One other important note:
“Keep in mind that if Metals starts Bloop, when you close Metals, it doesn't shut down the Bloop server. This is intentional. If you want to shut it down, you'll need to run a bloop exit.”
