research(nightly): page-coherent-memory — paged agent context loading via greedy coherence clustering

[ruvnet]

Summary

Nightly RuVector research: Page-Coherent Agent Memory — organizing vector memory stores into semantically coherent pages for faster retrieval and higher-quality agent context loading.

• Topic: Paged agent memory with greedy coherence clustering
• Crate: ruvector-coherence-pages (zero external dependencies, WASM-safe)
• ADR: docs/adr/ADR-280-page-coherent-memory.md
• Research doc: docs/research/nightly/2026-08-03-page-coherent-memory/README.md

What this adds

Three PageStore implementations benchmarked on 8,000 vectors × 128 dimensions:

Variant	Speedup vs flat	Recall@10	Coherence	Build
FlatStore (baseline)	1×	1.000	0.7533	0 ms
CentroidPageStore (k-means)	7.0×	0.346	0.7693	832 ms
GreedyCoherenceStore	9.6×	0.233	0.7782	65 ms

Key finding: greedy coherence achieves highest intra-page cosine similarity (+0.025 vs flat) but lower recall than centroid paging. K-means centroids are better retrieval anchors; greedy seeds produce tighter topic clusters for context loading. Both achieve 7–10× speedup at 10% probe rate. All 8 acceptance criteria pass.

Files changed

• crates/ruvector-coherence-pages/ — new crate (zero deps)
  • src/lib.rs — PageStore trait, VecPage, utilities, 6 unit tests
  • src/flat.rs — exhaustive baseline
  • src/centroid.rs — k-means centroid paging
  • src/greedy.rs — greedy coherence paging
  • src/bin/benchmark.rs — benchmark binary with real measured numbers
• docs/adr/ADR-280-page-coherent-memory.md
• docs/research/nightly/2026-08-03-page-coherent-memory/README.md
• docs/research/nightly/2026-08-03-page-coherent-memory/gist.md
• Cargo.toml — added ruvector-coherence-pages to workspace members

Test status

cargo test -p ruvector-coherence-pages
running 6 tests
test tests::dot_and_normalize_correct ... ok
test tests::flat_store_recall_perfect ... ok
test tests::page_coherence_greedy_beats_flat ... ok
test tests::centroid_store_builds_correct_pages ... ok
test tests::greedy_store_recall_above_threshold ... ok
test tests::centroid_store_recall_above_threshold ... ok
test result: ok. 6 passed; 0 failed; 0 ignored; 0 measured

Benchmark: cargo run --release -p ruvector-coherence-pages --bin benchmark → RESULT: ALL CHECKS PASSED ✓

Ecosystem connections

Page-coherent memory bridges: vector search + agent memory + coherence scoring + DiskANN-style paging + WASM edge deployment + MCP tool surface + ruFlo recompaction workflows.

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