feat: add Markdown polymode

config.org

@@ -4260,6 +4260,41 @@ Some more convenient leader key bindings would be nice to prevent having to traw
       "c L" #'lsp-avy-lens)
 #+end_src
 
+** Markdown
+
+#+call: confpkg("Mode: Markdown")
+
+*** Polymode
+
+Markdown allows for inserting code from other languages into itself. To make this integration more seamless, we can use the =poly-markdown= package to add syntax highlighting and major mode features of the corresponding language to the buffer.
+
+#+begin_src emacs-lisp :tangle packages.el
+(package! poly-markdown)
+#+end_src
+
+#+begin_src emacs-lisp
+(add-hook! markdown-mode #'poly-markdown-mode)
+#+end_src
+
+**** Agda Polymode
+
+The Agda integration with Markdown specifically requires some changes to the polymode, as its syntax highlighting scheme is different from the usual =font-lock= system that it expects.
+
+#+begin_src emacs-lisp
+(after! poly-markdown
+  (object-add-to-list
+   poly-markdown-fenced-code-innermode :init-functions
+   (defun ~/polymode-agda2-init-function (_)
+     (when (eq major-mode 'agda2-mode)
+       (font-lock-mode 0)
+       (setq indent-line-function #'indent-relative)))))
+
+(after! agda2-mode
+  ;; This highlighting interferes with Markdown's styling
+  (setq agda2-highlight-faces
+        (assq-delete-all 'background agda2-highlight-faces)))
+#+end_src
+
 ** Slint
 
 #+call: confpkg("Mode: Slint")