Hybrid retrieval

Hybrid retrieval runs both keyword search (like BM25) and semantic search (embeddings), then fuses the two ranked lists into one. Keyword search catches exact terms; semantic search catches paraphrases and synonyms. Together they miss less than either one alone.

In independent benchmarks, hybrid retrieval followed by a reranker is consistently the strongest setup, often by wide margins. It is the boring, reliable core that a clever agent sits on top of, not a replacement for it.