How to imitate `twoside=semi` in ConTeXt?

Question

ConTeXt's page setup seems to be very powerful for single pages. But as I am used to the powers of KOMA there is something I could not achieve: twoside=semi.

From what I have read I need to set up the page numbering to alternative=doublesided for being able to differentiate between odd and even pages. However, this will force the layout to flip sides (margins are adapted). Basically, I want to have the following layout (not to scale).

-----------------------  -----------------------
|                     |  |                     |
| -- ---------------  |  | --  --------------  |
| || |             |  |  | ||  |            |  |
| || |             |  |  | ||  |            |  |
| || |             |  |  | ||  |            |  |
| || |             |  |  | ||  |            |  |
| -- ---------------  |  | --  --------------  |
|                     |  |                     |
| ------------------  |  | ------------------  |
| | #                 |  |                # |  |
| ------------------  |  | ------------------  |
|                     |  |                     |
-----------------------  -----------------------

Code for a single-sided version:

\setuppagenumbering [alternative=singlesided,location={footer}]

\setuplayout        [grid=yes,
                     rightedge=1.25cm,
                     rightmargin=0pt,
                     rightmargindistance=0pt,
                     backspace=6cm,
                     leftmargin=4cm,
                     width=fit]
\showframe


\starttext
    Quack\margintext{Test}
    \page
    Quack\margintext{Test}
    \page
    Quack\margintext{Test}
\stoptext

So my question is: How to get double-sided page numbers while having a single-sided margin setup (margin with margin text on the left)?

What I have tried:

• messing around with footer setup and page number modulo 2 expressions
• layers (unfortunately their odd and even page detection only works for alternative=doublesided)
• using alternative=doublesided and \definelayout[even][…] to be the same as the \setuplayout

Answer 1

To create a document which has left and right pages but use the same layout for both of them use location={singlesided,doublesided} for \setuppagenumbering.

The location of the page numbers can be set with the \setupfootertexts command but you have add location= (or location=none) to \setuppagenumbering to disable the automatic placement of the number.

\setuppagenumbering
  [location=,
   alternative={doublesided,singlesided}]

\setupfootertexts
  [] [pagenumber]
  [pagenumber] []

\starttext
\dorecurse{2}{\page[dummy]}
\stoptext