Semantic search is good at understanding what somebody means. By default it understands it across your whole catalogue.
Most of the time that is exactly right. Sometimes it is not. A visitor already browsing your Winter collection should not get a summer jacket back, however well it matches the words they typed. A course platform showing the Business track should not answer with a Photography lesson. The shopper's question is the same either way. What changes is which shelf the question is asked of.
That is what filter_ parameters are for. One addition to the search URL, and the AI runs on the slice you chose.
