Most of this work runs on other companies' websites, so it has to fit hundreds of storefronts I don't control.
Search, recommendations and widgets each ship as one script. Per-brand behavior lives in configuration: selectors, layouts, synonyms, strategies, labels. A new brand is a config file, not a code fork, and teammates outside engineering can set one up from the docs.
Because the scripts load on third-party pages, the same problems come back on every project: the host's CSS leaking in, consent banners and other vendors' scripts racing ours, slow networks, Turkish text and number formats, and keyboard users. The case studies show how each system handles them.