feat: REPLs, by major mode, by project

Also includes Doom's popup code. }:)

users/crumb/programs/emacs/lib/syd-project.el

@@ -0,0 +1,12 @@
+;;; syd-project.el -*- lexical-binding: t; -*-
+
+(eval-when-compile (require 'cl-lib))
+(require 'project)
+
+(cl-defun syd-project-root (&key (dir default-directory))
+  "Return the project root of DIR, or nil if DIR belongs to no project."
+  (when-let* ((project (project-current nil dir)))
+    (project-root project)))
+
+(provide 'syd-project)
+;;; syd-project.el ends here