JinjaTemplate doesn't work

Hi guys,
I want to customize the web view of built-in app called Messages.

 FIrstly, I find the templates in /frappe/core/page/messages. 
           [ messages.html, messages.js, messages.py]

  But I find that messages.html doesn's support the Jinja template or frappe doesn't render this file .
  And the web view of built-in app Message is rendered by messages.js.

  The problem: why Jinja doesn;t work?


in-app (desk) pages are rendered via java-script.

You can add the feature here though:

Very thanks.
But in my opinion, separating view(html) and controll(js) is better and readable.

Thx,I have to say, Frappe is amazing :blush: