This sounds small until you have seen a tool audit itself into nonsense. The minute you inject a panel, controls, overlays, and support markup into the page, you have changed the page. If you do not handle that properly, your own interface starts polluting the scan.
A11Y Cat explicitly carves out its own UI from the normal audit surface. It also keeps route-aware scan state, which matters on sites where the DOM and URL can change under your feet. That is the sort of detail people ignore right up until the results stop being trustworthy.
I like this feature because it is quiet and disciplined. Nobody markets self-exclusion. Nobody gets excited about contamination boundaries. But this is exactly the sort of engineering that separates a demo from a tool you can use day after day without second-guessing it.
A lot of my decisions in this project come back to one thing: if the tool can lie to me by accident, I want to close that hole.
Documentation trail
ARCHITECTURE.mdTECHNICAL_GUIDE.md
