Breadcrumb
Breadcrumb shows where the current screen sits in a hierarchy, and takes people back up it.
Preview
A hierarchy trail. Three levels, the last one active. Rare on mobile by the file's own description, worth it only when a drill-down runs deeper than Back can explain.
The last item is the page you are on, so it takes the strong tokens and stops being a link. Everything before it stays sub.
Quantity
Two to five levels. The track hugs, stays 20 tall and adds 140 for every level past the first: eight of gap, the sixteen wide chevron, eight again, then the 108 item.
668 does not fit a 390 screen, or this column. The track scrolls in place instead of wrapping, because a breadcrumb on two lines stops reading as one line of descent.
Item
The building block behind every level. One state axis and two booleans, so a level can be an icon and a label, a label alone, or an icon alone.
Default paints fg/sub-700 and text/sub-700, Active paints fg/strong-950 and text/strong-950. Icon and label always carry the same value, so one rule moves both. The chevron stays fg/soft-500 at every level. Text false is the usual first level.
Properties
One axis on the published component. The rest sit on the item inside it, a building block not meant for direct use.
Breadcrumb ships 4 variants, one per quantity. The item ships 2, one per state, and is composed into all four, so a change there reaches every level of every trail.
Tokens
Three values and nothing else. No fill, no border, no radius anywhere in the component.
The file names the icon halves separately, fg/sub-700 and fg/strong-950, and both resolve to the same primitive as their text counterpart in both modes.
Guidelines
Save it for a drill-down deep enough that Back stops answering the question. Drop the label on the root and let the icon carry it.
Two levels do not need a trail. One step back is a Back button, and a breadcrumb there spends a whole row saying what the header already said.
The component's own description is blunt about it: rare on mobile, only for deep drill-downs.