05 · Slope Chart.

Comparing the same metric across the same set of categories at exactly two points in time. Outcome scores 2024 vs 2025, NPS Q1 vs Q4. Lines that cross are a feature, not a bug — they show category rank-flips, which a side-by-side grouped bar makes invisible.

Each <line> draws left → right via the same stroke-dasharray trick as the line chart. Dots fade in when the line arrives at each end. Labels follow the dots. Stagger 100ms per series so the eye can track each line individually.

outcomeScores: {
  leftYear:  2024,    // editable
  rightYear: 2025,
  series: [
    { label: 'Cardiology',
      left: 78, right: 86,
      color: 'var(--primary)' },
    // any number of series
  ],
}

const all   = series.flatMap(s => [s.left, s.right]);
const minV  = Math.min(...all) - 5; // pad bottom
const maxV  = Math.max(...all) + 2; // pad top
const scale = (v) =>
  padTop + (1 - (v - minV) / (maxV - minV)) * usableH;