Tufte-style charts

skill · published by agentleFS · version 1 · approved by frdchang@gmail.com on 2026-10-12

Clean, directly labelled charts from a JSON spec that read in light and dark mode: stacks, lines, slopegraphs, small multiples.

Mount

examples/made-up/lines.spec.json

{
 "_note": "Made-up numbers, to show a line chart with gaps: a null value breaks the line, and the last value is null.",
 "data": {},
 "title": "Two made-up series with missing months",
 "subtitle": [
  "Series A went from {a[0]:.0f} to {a_last:.0f}, a negative value printed with a true minus. Series B went from {b[0]:.0f} to {b_last:.0f}."
 ],
 "periods": [
  "2026-01",
  "2026-02",
  "2026-03",
  "2026-04",
  "2026-05",
  "2026-06"
 ],
 "series": [
  {
   "label": "series A",
   "color": "#111",
   "values": [
    42,
    48,
    null,
    61,
    -3,
    null
   ],
   "counts": [
    10,
    12,
    0,
    15,
    9,
    0
   ]
  },
  {
   "label": "series B",
   "color": "#8a8478",
   "values": [
    30,
    33,
    35,
    null,
    41,
    44
   ],
   "counts": [
    8,
    8,
    9,
    0,
    11,
    12
   ]
  }
 ],
 "y": {
  "min": -25,
  "max": 75,
  "step": 25,
  "tick": "{:.0f}",
  "reference": 0
 },
 "value_format": "{:.0f}",
 "ylabel": "made-up units",
 "count_label": "n: A · B",
 "events": [
  {
   "date": "2026-03-10",
   "label": "an event"
  }
 ],
 "footnote": [
  "Made-up data for the smoke test."
 ]
}