Cells are sized by the Size column, colored by the Color
column, and nested by the Path columns (group-by order).
Path chips
Drag a chip left/right to reorder the group-by hierarchy;
the treemap re-lays out on the fly.
× on a chip removes that column from the path.
+ opens a checklist of every column so you can add more
levels (e.g. the synthetic _row which puts every
source row into its own leaf sliver).
Mouse
Hover: full path + size tooltip.
Click a cell to select it; the breadcrumb lights up.
Scroll wheel over a selected cell moves the highlight up or
down the ancestor chain.
Double-click a cell to zoom in. The depth budget re-applies
from the new root, so you can drill in and keep your bearings.
Breadcrumb
Click a segment to focus that ancestor;
double-click to zoom to it. The home icon jumps to the root.
Component toolbar
Depth: levels below the current zoom. +/−
or type a number; snaps to ∞ once you reach the deepest level.
Labels: draw each leaf's full path inside its cell when it fits.
URL
All state (Size / Color / Path / zoom / theme / palette / depth …)
is URL-encoded into the hash as a single JSON blob, so any view is
a copy-paste away.