Setting up LSP in Emacs

Untested. I don’t use Emacs, so this is the standard recipe rather than a verified setup. If you get it working (or it doesn’t), please let me know.

With eglot, built into Emacs 29+:

(with-eval-after-load 'eglot
  (add-to-list 'eglot-server-programs
               '(M2-mode . ("m2-ls"))))

(add-hook 'M2-mode-hook #'eglot-ensure)

M2-mode is the major mode from Macaulay2’s own Emacs package; the server works alongside it.