Clojure-lsp
Calva uses a mix of static and dynamic analysis to power the experience. A lot of the static abilities come from clojure-lsp. This enables you to check something up in a project, with a lot of navigational and contextual support, without starting a REPL for it. (And once you do start a REPL you'll get even more capabilities, enabled by the dynamic analysis.)
Starting the LSP server
You don't need to do anything to start clojure-lsp. No install, no commands, no nothing. Calva downloads the correct binary for your operating system if necessary (this should only happen when the clojure-lsp version is updated in a new release of Calva) and then starts it. It does take a while for clojure-lsp to start, though, especially the first time for a new project, when clojure-lsp (via clj-kondo) indexes the project files.
Calva will show a status bar message during the download and while the server is starting, which will go away once the server is ready. However, much of Calva's functionality is available regardless of the LSP server, so please start using Calva while this server is starting.
Ignoring LSP cache files
Clojure-lsp stores its project analysis information in your project. Git users can add these lines to their project root directory .gitignore:
.clj-kondo/cache/
.clj-kondo/.cache/
.lsp/sqlite.*.db
Troubleshooting
If something doesn't seem to be working correctly, and you suspect the issue is related to clojure-lsp, a good place to start investigating is the request and response logs between the LSP client and server. In your settings, set Clojure > Trace: Server to versbose, then in the VS Code output tab, select the Clojure Language Client output channel.
It may be helpful to clear the output channel, then perform the action with which you're experiencing a problem, then read through the log for clues or paste the logs into a related issue in the Calva repo.
Related
See also: