SmartRetrieval RRF+MMR

Single-strategy retrieval (BM25 or vector-only) misses complementary signals in the ReasoningBank.

Combine BM25 and TF-IDF scores via Reciprocal Rank Fusion, then apply Max Marginal Relevance to reduce redundancy.

Retrieval quality +22% on internal evals. 3ms overhead per query. Requires both indexes to be populated.