How many jobs the node stands for.
How many of them ended in error, so a surface can hue by share rather than by the worst.
The index of the parent group, or null at the root.
The plugin name.
The worst word among them: an error anywhere is the group's, else anything still moving, else finished.
One node of a feed's collapsed shape: every job of one plugin hanging from the same parent group, as one node with a count.