Streamgraph
Follow composition through centred layers.
Use a streamgraph for changing nonnegative contributions over an ordered X axis. The centred offsets describe geometry; they are never the reported data values.
Named series with stable id/x/y points. Values are nonnegative or null. A missing contribution breaks the entire row; no value is fabricated as zero.
Shared or individual detail preserves original values. Configure axes, colours, labels, legend, references and viewport. Centred stacking is fixed: no layout stacking, curve/gaps overrides, line width, markers or point colours.