The `ai_vdb_provider_elasticsearch` module (https://www.drupal.org/project/ai_vdb_provider_elasticsearch) implements the AI Search VDB interface against Elasticsearch's native `dense_vector` + HNSW. Currently, it is the only Drupal VDB provider offering native hybrid search (kNN + BM25 merged via Reciprocal Rank Fusion) in a single Elasticsearch request. Should be added to the matrix under the Vector Database column.