Originally posted by @deining in #526 (comment) :

I just realized that shortcode lead treats its .Inner content either as markdown or as HTML, depending on the extension of the page that makes use of the the shortcode:

{{ if eq .Page.File.Ext "md" }}
    {{ .Inner | markdownify }}
{{ else }}
    {{ .Inner | htmlUnescape | safeHTML }}
{{ end }}

Does it make sense to implement this for shortcode feature in a similar way?

IMHO, that is the wrong way to do it. When using a shortcode, one needs to use either {{< >}} or {{% %}} instead, depending on the content of the shortcode (HTML and markdown, respectively).

If we all agree that this is the way to go, then a number of files will need to be changed (which mostly were introduced by #378 I believe):

• blocks/feature reworked to support use from .md files #727
• layouts/shortcodes/alert.html - A better alert shortcode more markdown friendly #941
• layouts/shortcodes/card.html - [BSv5] Adapt cardpane shortcode #1376
• layouts/shortcodes/blocks/cover.html - shortcode 'blocks/cover': improvements #1400
• layouts/shortcodes/imgproc.html - Fix: shortcode imgproc does not work with % for markdown body #1522
• layouts/shortcodes/blocks/lead.html - shortcode 'blocks/lead' improvements #1398
• layouts/shortcodes/blocks/section.html - [BSv5] blocks/section row-col hierarchy fix #1472
• And other shortcodes, see the output of the GH search for .Page.File.Ext "md"

Related:

• Shortcodes: drop support for pre-Hugo-0.54.x behavior of {{% %}} #939