.onion capsules?

[Stephane Bortzmeyer]

On Fri, Mar 26, 2021 at 02:27:34PM -0700,
 Rohan Kumar <seirdy@seirdy.one> wrote 
 a message of 42 lines which said:

> Onion sites often have clearnet counterparts that send an HTTP
> header to inform the user agent that a hidden site exists;

The non-standard Onion-Location:
<https://community.torproject.org/onion-services/advanced/onion-location/>.

> Some way to inform the user agent to switch to the hidden version
> when available would be appreciated,

Yes, but I'm not sure how to do it without headers. In the DNS?