Can't display more than 2 swatches for quantitative data

[stevage]

I'm not sure if this is a bug, a feature request or support request.

I have a dataset which has approx 10 discreet values, integers from 0 to 15.

I'd a like a legend to display a reasonable number of those values (most likely, all of them). I'm setting it up like this:

const plotEl = Plot.plot({
  marks: [
    Plot.rectY(
        expeditions,
        Plot.binX(
            { y: 'count' },
            {
                x: {
                    value: 'date',
                    interval: d3.utcMonth,
                },
                fill: 'participantsCount'
            }
        )
    ),
  ],
  background: '#222',
  width: document.getElementById('chart').getClientRects()[0].width,
      style: {
          background: '#222',
          color: 'white',
      },
  });
  const legendEl = plotEl.legend('color', {
      legend: 'swatches',
      columns: 8,
      style: { color: 'white', background: '#222' },
  });
  document.getElementById('chart').replaceChildren(plotEl);

I can't see anything in the docs that offers a way to display more swatches.

Result:

Of note:

• only two swatches (min and max value)
• also some strange artefacts that look like a 1 pixel height swatch

See in action here (select Show chart, Number of participants).