[danielearwicker]

It ought to be possible for the page to disable JavaScript with a meta tag:

  <meta name="noscript">

The browser could put an extra icon next to the https padlock so the user would know they were viewing a document rather than an application.

[labawi]

There seem to be a HTTP header[1] you could use. No icon though. And I'm not sure how much the restriction could be evaded by interactive Turing-complete CSS or similar features.

[1] https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Co...