The cross-encoder reranker is off by default (enable_rerank=False everywhere)
and adds a second model download plus a candidate-widening pass on every search.
Removing it keeps the core retrieval (parse, chunk, embed, BM25 + dense, RRF,
search_knowledge_base tool) intact while dropping ~375 lines.
- delete core/rag/reranker.py and its test
- drop enable_rerank / reranker_model from the search tool, tools dispatch,
and the /rag/search route (candidate_k is now just top_k)
- remove the /rag/reranker/precache endpoint and reranker config knobs
- update tool-handler test to the trimmed rag_scope shape
42 RAG tests pass.
b085b37b69