* feat(ruvector): real float HNSW + SymphonyQG-style quantized-traversal index (ADR-261)
Adds the graph-ANN index the ruvector retrieval path was missing (ADR-156
§5 #1 noted there was no HNSW baseline to measure SymphonyQG against).
- hnsw.rs: correct float HNSW (Malkov & Yashunin) — multi-layer NSW graph,
ef_construction/ef_search, Algorithm-4 neighbour selection, seeded-
deterministic level assignment (SplitMix64, reused from rotation.rs),
L2 + cosine, brute-force ground truth, full degenerate-case guards.
recall@10 correctness gate >=0.95 vs brute force (L2 + cosine).
- hnsw_quantized.rs: SymphonyQG-style variant — same graph, traversal scored
by cheap 1-bit Hamming over the RaBitQ Pass-2 rotated sign code, final
exact-float rerank.
- ann_measure.rs: shared deterministic planted-cluster fixture + recall/QPS
measurement (ann_bench_report is the ADR source of truth).
Fixes an index-out-of-bounds bug the recall gate caught: insert wired
bidirectional edges before pushing the node's own link row. +20 tests,
ruvector lib 131->151, 0 failed.
Co-Authored-By: claude-flow <ruv@ruv.net>
* bench(ruvector): criterion ann_bench for HNSW vs quantized vs linear (ADR-261)
Times the same shared ann_measure fixture/indices through criterion so the
bench and the report test can never measure different graphs.
Co-Authored-By: claude-flow <ruv@ruv.net>
* docs(adr-261): graph-ANN index ADR with MEASURED HNSW vs quantized verdict
ADR-261 (Accepted): float HNSW ~25x QPS over linear scan at recall >=0.99
(the baseline ADR-156 said was missing). Honest negative: the 1-bit
quantized traversal is too coarse to beat float HNSW at equal recall at
N=10k (best recall 0.738, no >=0.90 equal-recall point) — the SymphonyQG
3.5-17x is NOT reproduced by our 1-bit construction; expected crossover at
large N + a multi-bit code. Caveat: our HNSW + our quant, not SymphonyQG's
system — direction tested, not a 1:1 reproduction.
ADR-156 §5 #1 + §8 backlog: CLAIMED -> MEASURED-direction-tested.
CHANGELOG [Unreleased] entry.
Co-Authored-By: claude-flow <ruv@ruv.net>
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