The shelf — copy from here
Admin → UI lab → Engine → Charts is the living catalog: column bars,
dot plot (the ranking form), line+area with endpoint label, donut paired
with the same data as ranked dots (when the question is "which is bigger",
the dots win — the donut earns its place only for "how much of the
whole"), horizontal bars, the calendar heatmap (CSS .bg cells — intensity
IS --bg; not every "chart" needs SVG), and the stat-tile sparkline. The
general builders (ChartPoint, barColSVG, dotPlotSVG, lineAreaSVG,
donutSVG, fbHBarSVG, concurrencyLine) live in view/chartrender.go —
extend those before writing a new one.
See references/worked-example.md for the full toggle command + legend-tag wiring.