research(nightly): adaptive-sq-coherence — mixed-precision SQ with coherence-precision routing

[ruvnet]

Summary

Nightly RuVector research for 2026-07-17: Adaptive Scalar Quantization with Coherence-Precision Routing.

Core idea: route each stored vector to 8-bit or 16-bit scalar quantization at insert time, based on its local neighbourhood density score (mean kNN L2 distance). Dense, contested embedding regions get 16-bit precision; sparse regions get 8-bit. The result is a memory:recall Pareto improvement over both uniform options.

• Recall@10: AdaptiveSQ 0.9520 vs Uniform8 0.8235 vs Uniform16 1.0000
• Memory: AdaptiveSQ 195 KB = 62.5% of Uniform16 (312 KB) and 125% of Uniform8 (156 KB)
• Latency overhead: +2.7% vs Uniform8 (421 µs vs 410 µs)
• Both acceptance tests pass: recall ≥ 0.93 × Uniform16; memory ≤ 75% × Uniform16

All numbers from cargo run --release -p ruvector-adaptive-sq --bin benchmark, seed=42, N=5000, dim=32, 200 queries, k=10.

Deliverables

• Crate: crates/ruvector-adaptive-sq — zero external deps (library), builds to WASM unmodified
• Tests: 17 unit tests, all passing (cargo test -p ruvector-adaptive-sq)
• Benchmark: cargo run --release -p ruvector-adaptive-sq --bin benchmark
• ADR: docs/adr/ADR-272-adaptive-sq-coherence.md
• Research doc: docs/research/nightly/2026-07-17-adaptive-sq-coherence/README.md
• Public gist: docs/research/nightly/2026-07-17-adaptive-sq-coherence/gist.md

Ecosystem Connections

Connects: RuVector vector search + coherence scoring + agent memory + edge WASM + RVF + ruFlo.

Known Limitations (documented in ADR)

• Build time is O(N²) for brute-force density scoring — Phase 2 replaces with HNSW-based approximate kNN
• Static routing; streaming density score updates are a Phase 2 item
• Benchmark uses synthetic clustered data; real embedding distributions may show smaller routing accuracy

Build Status

cargo build --release -p ruvector-adaptive-sq  ✓
cargo test -p ruvector-adaptive-sq             ✓  17/17 pass
cargo run --release -p ruvector-adaptive-sq --bin benchmark  ✓  PASS

---

Generated by Claude Code