feat(rag): hybrid multi-path search with RRF fusion

Add configurable hybrid mode on KnowledgeSearchPort that fuses dense unfiltered, dense filtered, and lexical ranks via RRF while preserving dense-compatible threshold scores. Archives Delivery 2 OpenSpec change.
2026-07-27 18:33:31 +08:00
parent ac1f831903
commit 376ad0c241
19 changed files with 661 additions and 8 deletions
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+# Tasks: rag-hybrid-search-rrf
+
+- [x] 1. Add RRF fusion utility
+- [x] 2. Extend KnowledgeSearchRequest/Hit metadata for fusion ranks
+- [x] 3. Implement hybrid multi-path search in VectorKnowledgeSearchAdapter
+- [x] 4. Wire retrieval.search.mode and rrf config
+- [x] 5. Pass mode from LookupKnowledgeTool / retriever
+- [x] 6. Unit tests for RRF and hybrid adapter ordering
+- [x] 7. Verify dense mode regression tests still pass