Why the filter counts are context-aware

Every filter chip on the list page carries a number beside it. That number is not the total in the catalogue; it is how many results you will see if you pick that filter. The difference looks small and changes the behaviour completely.

An interface with fixed counts produces this scene: "Air" is selected, and a number still sits next to a land brand. You click, and the page empties. The interface has not exactly lied to you — but what it said was not the answer to the question you asked.

Here the counts are computed per group with every active filter applied except the group's own dimension. While "Air" is selected, brand counts are computed within air vehicles only. The counts on the other options in the main-category group answer a different question: what you would find if you switched to that mode. Leaving a group's own dimension out is standard facet behaviour.

This has a visible consequence: an option that would return nothing is not shown at all. The only exception is the active option, which has to stay on screen so you can remove it. Every button you can see therefore leads to a page with something on it.

The same discipline applies to pagination. When the results do not fit on one page, the list continues through links, and those links appear in the address bar. This is not only about clickability: a "next" control that opens only under JavaScript is absent from the first HTML response, and for any software reading the page those results do not exist. For the other axes of navigation, see How to read this catalogue.