DEEP DIVE
Why not just vector search?
Vector Search
bge-small-en-v1.5 (384d). Finds conceptually related code even with different naming.
Recall: 0.78
bge-small-en-v1.5 (384d). Finds conceptually related code even with different naming.
Recall: 0.78
FTS5 (BM25)
Exact keyword matching. Catches function names and identifiers vector search fuzzes over.
Recall: 0.72
Exact keyword matching. Catches function names and identifiers vector search fuzzes over.
Recall: 0.72
RRF Fusion
Reciprocal Rank Fusion (k=60) merges both. Confidence blends similarity, keywords, recency.
Recall: 0.90
Reciprocal Rank Fusion (k=60) merges both. Confidence blends similarity, keywords, recency.
Recall: 0.90
Neither retriever is good enough alone. Together they cover each other's blind spots.