How to not update Page-Counter on inserted blank pages with pagebreak to odd

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1

I am currently in the process of writing my own letter-template. It should support multiple letters per file, page-numbers and double-sided printing.

I adapted How to reset the page counter after every section? - #10 by laurmaedje to reset the page-counter on each new letter.

But now the page-counter does not account for the fact, that an empty page might have been inserted if the letter was only one page long (because a pagebreak to odd has been inserted in order to support double-sided printing of the letters).

//https://forum.typst.app/t/how-to-reset-the-page-counter-after-every-section/1924/10
#let reset = <__reset>

#let subtotal() = {
  let loc = here()
  let list = query(selector(reset).after(loc))
  if list.len() > 0 {
    counter(page).at(list.first().location()).first() - 1
  } else {
    counter(page).final().first()
  }
}

#let page-numbers = context {
  let subtotal = subtotal()
  //Dont show page-numbers if there is only one page in the letter
  if subtotal == 1 {
    none
  } else {
    numbering("1 / 1", ..counter(page).get(), subtotal)
  }
}

#let letter(
  to: [],
  body,
) = {
  pagebreak(weak: true, to: "odd")
  [#metadata(none)#reset]
  counter(page).update(1)
  pagebreak(weak: true)

  set page(
    footer: context {
      align(center, page-numbers)
    },
  )

  to
  body
}

#show: letter.with(to: [To someone])

#lorem(50)

#show: letter.with(to: [To someone else])

#lorem(1000)

So my question is: How do I adapt the code, so that the subtotal-function in the MWE reports the number of pages in the letter not including the possibly inserted blank page?

Merci.