Verifying LSP Works

After installing a language server in Mason, confirm everything is wired up correctly.

Open a file of that language (e.g., nvim test.py) and run these checks:

Check	How	What you should see
LSP attached	`:checkhealth vim.lsp`	Server listed as "attached"
Completion works	Type `import os` then `os.`	Popup with functions
Go-to-definition	Place cursor on a function call, press `gd`	Jumps to definition
Hover docs	Place cursor on a symbol, press `K`	Floating documentation window
Diagnostics	Make a syntax error, wait 1 second	Red underline and gutter marker
Manual completion	Press `<C-Space>`	Force-opens the completion menu

If something isn't working

:checkhealth vim.lsp shows "no client attached" — install the server in :Mason and reopen the file.
Completion doesn't appear — make sure the file type is detected. Try :set ft? — it should show the language (e.g., filetype=python). If not, use :set ft=python.
Diagnostics don't show — check :checkhealth vim.lsp to confirm the server is running. Some servers need a few seconds to start.
Completion menu appears but has no LSP results — press <C-Space> to force the menu. If still empty, check :checkhealth vim.lsp for a running server.