93 lines
3.9 KiB
Markdown
93 lines
3.9 KiB
Markdown
# Tick 15 — 2026-05-22 06:40 UTC
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**Thread:** ADR-106 (DP-SGD + biometric primitive isolation)
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**Verdict:** Closes the two items deferred from ADR-105 (member-inference defence + primitive isolation enforcement). The federation protocol now has formally-bounded privacy.
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## What shipped
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- `docs/adr/ADR-106-dp-sgd-and-primitive-isolation.md` — full ADR draft. Direct extension of ADR-105.
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## Three-layer defence
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| Layer | Mechanism | Defends against |
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|---|---|---|
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| 1 — Primitive Isolation | API-level tagging of on-device-only tensors (R15 binding list) | Exfiltration of biometric primitives via federation channel |
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| 2 — Gradient clipping | Per-sample L2 norm bound (Abadi 2016) | Bounds sensitivity of any single training sample |
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| 3 — Gaussian noise | Per-round N(0, σ²C²I) on aggregated delta | Formal (ε, δ)-DP via Moments Accountant |
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## Privacy budget
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Recommended (per Moments Accountant, δ=1e-5):
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| Profile | σ | Rounds | Total ε | Use |
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|---|---:|---:|---:|---|
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| Conservative (medical-grade) | 1.5 | 50 | **2.0** | HIPAA-aligned |
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| Standard (typical RuView) | 1.0 | 100 | **5.0** | Most cogs |
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| Lenient | 0.5 | 100 | 8.0 | Below ε=10 community soft-bound |
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## On-device-only primitive list (R15-binding)
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7 ✅ "never transmit" primitives:
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- Raw CSI window
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- Gait stride frequency
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- Breathing rate (per-subject)
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- HRV rate signature
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- RCS frequency response curve
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- Limb timing vector
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- Per-subject embedding centroid
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3 ⚠️ "transmit with mitigation":
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- MERIDIAN per-room centroid (aggregate, OK)
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- LoRA weight delta (DP-SGD applied)
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- Model logits during inference (never aggregated)
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API surface enforces ✅ as compile-time error where possible.
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## Implementation budget
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Extends ADR-105's 500 LOC by **+300 LOC**: PrimitiveTag (60) + clipping (30) + DP noise (40) + Moments Accountant (120) + per-cog config schema (50). Total federation budget: **~800 LOC, 3-week effort**.
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## Why this closes the privacy story
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R3 + R14 + R15 + ADR-105 + ADR-106 = complete chain from physics (R6 forward model) → embeddings (R3) → personalised features (R14) → trained how (ADR-105) → defended how (R7) → privacy-bounded how (ADR-106).
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The chain has:
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- A physics floor (R6/R1)
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- A spatial intelligence layer (R5/R7/R3)
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- A vertical roadmap (R10 wildlife + R11 maritime + R14 home)
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- Two negative results (R12 eigenshift, R13 contactless BP)
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- Two architectural decisions (ADR-105 + ADR-106)
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The per-occupant feature surface (R14 V1/V2/V3) now has **formal (ε, δ) privacy backing**, not just policy.
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## Composes with every prior thread
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- R3: Layer 1 blocks per-subject embedding centroid transmission
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- R7 mincut: compatible with DP-noised deltas; operates on noised graph
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- R12/R13 negative results: informed the noise-vs-structure-detection design choice
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- R14: privacy framework now has formal (ε, δ) backing
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- R15: requirements basis = on-device-only primitive list made executable
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- ADR-105: 800 LOC budget, DP slots into step 4 of protocol
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## Honest scope
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- σ values are recommendations, not measurements (per-cog tuning needed)
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- (ε, δ)-DP is worst-case bound; auxiliary info changes the practical leakage
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- Moments Accountant is conservative (slightly over-estimates budget consumed)
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- Subject-level DP not formalised (household of 4 has K=4 subjects → sample-level DP doesn't fully capture)
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- Side-channel timing leaks out of scope (future ADR)
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## Coordination
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`ticks/tick-15.md`. No PROGRESS.md edit. Branch `research/sota-adr106-dp-sgd-primitive-isolation`.
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## Remaining loop work (post ADR-106)
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- R6.1 multi-scatterer Fresnel extension
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- R3 follow-up: physics-informed env_sig prediction (zero-shot cross-room)
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- R6.2 Fresnel-aware antenna placement CLI tool
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- ADR-107: cross-installation federation w/ secure aggregation (explicitly deferred from ADR-106)
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- Loop retrospective / 00-summary.md (premature — ~5h still on clock)
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~5.3h to cron stop. **15 ticks landed. PROGRESS.md research agenda + 1 follow-up ADR closed.**
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