Install the ob-mermaid package

configuration.org

@@ -2978,6 +2978,14 @@ An alternative could be
   (org-mode . org-bullets-mode))
 #+END_SRC
 
+** Edit diagrams with mermaid
+
+#+BEGIN_SRC emacs-lisp
+(use-package ob-mermaid
+  :custom
+  (ob-mermaid-cli-path "/home/polesz/.local/node/bin/mmdc"))
+#+END_SRC
+
 * Git & Co.
 
 ** Git status on the fringe

customizations.el

@@ -159,6 +159,7 @@
      ng2-mode
      nyan-mode
      nyan-prompt
+     ob-mermaid
      ob-restclient
      objed
      org