research(nightly): temporal-coherence-agent-memory

[ruvnet]

Nightly Research: Temporal Coherence Decay for Agent Memory Retrieval

Adds crates/ruvector-temporal-coherence — a pure Rust crate scoring agent memories by temporal decay and graph-coherence gating.

What's included

1. Working Rust PoC — crates/ruvector-temporal-coherence with three VectorSearch variants
2. ADR-211 — docs/adr/ADR-211-temporal-coherence-agent-memory.md
3. Research document — docs/research/nightly/2026-06-13-temporal-coherence-agent-memory/README.md
4. Public gist — docs/research/nightly/2026-06-13-temporal-coherence-agent-memory/gist.md
5. Real benchmark results — all 4 acceptance tests pass

Three retrieval variants

Variant	Scoring	Primary fitness
FlatSearch	cosine similarity	cosine_recall=1.000 ✓
TemporalSearch	cosine × exp(-λ·age)	recency=0.962 ✓
CoherenceSearch	cosine × (decay + graph gate)	coh_gate=0.971 ✓

Benchmark (N=5 000, D=128, K=10, 200 queries, Rust 1.94.1)

FlatSearch    mean=1036µs  p50=1017µs  p95=1136µs  965 q/s  recall=1.000  PASS
TemporalSearch mean=1033µs p50=1020µs  p95=1096µs  967 q/s  recency=0.962 PASS
CoherenceSearch mean=1070µs p50=1053µs p95=1179µs  935 q/s  coh_gate=0.971 PASS

Ecosystem connections

• Fills the gap between ruvector-core (cosine search), ruvector-temporal-tensor (compression), and ruvector-coherence (quality metrics)
• Trait-based API — swap FlatSearch → CoherenceSearch without changing caller code
• Zero external dependencies beyond rand (for benchmark dataset generation)
• MCP tool surface planned: expose half_life_hours and coherence_weight as tool parameters
• WASM/Cognitum Seed compatible: no unsafe blocks, pure safe Rust

Research doc

docs/research/nightly/2026-06-13-temporal-coherence-agent-memory/README.md

ADR

docs/adr/ADR-211-temporal-coherence-agent-memory.md

Top alternatives considered (not selected this run)

• gMMR diversity (score 4.50) — recommended as next nightly topic
• QuIVer 2-bit topology quantization (score 4.45)
• Agent memory compaction via mincut (score 4.05)

Run it

git checkout research/nightly/2026-06-13-temporal-coherence-agent-memory
cargo test -p ruvector-temporal-coherence
cargo run --release -p ruvector-temporal-coherence --bin tcd-benchmark

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