The hybrid_search RPC always returns up to recall_k dense neighbours, so a
query for a term absent from the corpus (e.g. "varginha") returned its 12
nearest vectors — irrelevant chunks like PAGE_NUMBER "1". Two bugs:
the reranker was skipped whenever results <= top_k, and there was no relevance
floor.
Now always run the cross-encoder reranker (BGE-reranker-v2-m3, normalized
sigmoid) and drop hits below 0.02. Verified: "varginha" → 0 results;
"roswell"/"tic tac"/"disco voador" → relevant hits on top (reranker cleanly
separates 0.0001 garbage from 0.03-0.27 matches).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
