hybrid retrieval

Pure vector search drops exact terms; pure keyword search drops meaning. The signal is understanding why each fails on its own and how to merge two rankings on incomparable scales without hand-tuning weights. Here is the answer.

A dense encoder given 'refund policy' has almost nothing to work with. The fix is counterintuitive and it is not a better embedding model, and the reason this bug survives your eval set is worse than the bug.

E-commerce search is where retrieval, ranking, and business goals meet, and it carries a strict exact-match requirement (brand, size, SKU). The signal is query understanding plus hybrid retrieval plus business-aware ranking. Here is the design.