slide-number updates after first page during reveal

[derdilla]

I have a simple slide with a progress indication similar to https://polylux.dev/book/toolbox/progress.html, with the exception that I do
#set page(header: my-progress) to add the progress to each slide.

When I create the nth slide with an animation:

#slide[
  === tst
  reveal-code(lines: (1,2,3), after:gray)[```
    A
    B
    C```]
]

The PDF creates the slide n for the slide with A highlighted, and the slides numbered with n+1 for the other subslides and the next slide.

[andreasKroepelin]

So you mean slide n+1 occurs twice? And what does it have to do with the progress header?

[derdilla]

I think this example illustrates it:

Sample code

#import "@preview/polylux:0.4.0": *

#set page(paper: "presentation-16-9")

#let progress = {
  [#toolbox.slide-number / #toolbox.last-slide-number]

  toolbox.progress-ratio(ratio => {
    stack(
      dir: ltr,
      rect(stroke: blue, fill: blue, width: ratio       * 8cm),
      rect(stroke: blue, fill: none, width: (1 - ratio) * 8cm),
    )
  })
}

#set align(horizon)

#slide[
  Slide 0
]

#set page(header: progress)

#slide[
  Slide 1
]

#slide[
  Slide 2

  #show: later

  B
]

#slide[
  Slide 3
]

Output

You can see that the numbering as well as the progress passed to slide 2 part B are wrong. One notable precondition I missed before is that there is no progress displayed on the first slide.

[andreasKroepelin]

So the #set page(header: progress) between slides 0 and 1 makes a difference?