{
  "$schema": "urn:prism:schema:v1:spec",
  "title": "Seats in use (step interpolation)",
  "data": {
    "name": "seats_in_use",
    "values": [
      {"day": "2026-01-01", "seats": 12},
      {"day": "2026-01-02", "seats": 12},
      {"day": "2026-01-03", "seats": 19},
      {"day": "2026-01-04", "seats": 19},
      {"day": "2026-01-05", "seats": 31},
      {"day": "2026-01-06", "seats": 28},
      {"day": "2026-01-07", "seats": 40}
    ]
  },
  "mark": {"type": "area", "interpolate": "step", "fill_opacity": 0.7},
  "encoding": {
    "x": {"field": "day",   "type": "temporal"},
    "y": {"field": "seats", "type": "quantitative"}
  }
}