if (doc != null && doc.get(idField) instanceof final String id) {
                    // Calculate RRF score: 1 / (rank_constant + rank)
                    final float rrfScore = 1.0f / (rankConstant + docRank);
                    if (documentsByIdMap.containsKey(id)) {
                        final Map<String, Object> existingDoc = documentsByIdMap.get(id);