wifi-densepose/examples/research-sota/05-cross-room-reid/README.md

05 — Cross-room person re-identification (R3 arc, 3 ticks)

Whether the same person can be identified across two different rooms with WiFi CSI. Three-tick arc: R3 baseline → R3.1 (architecture error negative) → R3.2 (corrected architecture, structurally validated).

Scripts (in arc order)

Script	Thread	Headline	State
r3_crossroom_reid.py	R3	MERIDIAN env-centroid subtraction recovers cross-room re-ID to 100% (synthetic 128-dim embedding setup)	POSITIVE
r3_1_physics_informed_env.py	R3.1	Physics-informed env subtraction at raw-CSI level FAILS (10% = chance). Even labelled MERIDIAN at raw CSI = 10%. Identifies architecture error: position-variance dominates at raw level.	NEGATIVE (architecture-error)
r3_2_embedding_physics_env.py	R3.2	Embedding-level physics-informed env: 20% = matches labelled oracle with zero labels. Architecture correct; per-subject signal weak in synthetic AETHER stand-in.	STRUCTURALLY VALIDATED

The three-kind-of-negative pattern

R3.1 was the loop's first architecture-error negative:

Kind	Example	Path forward
Missing-tool (revisitable)	R12 → R12 PABS	Tool arrives later; approach works
Physics-floor (permanent)	R13 contactless BP	Hard wall; no tool changes this
Architecture-error (correctable)	R3.1 (here)	Wrong application level; corrected sketch explicit

Corrected architecture (R3.2)

raw CSI → AETHER embedding (position-invariant, ADR-024)
              → physics-informed env subtraction (uses R6.1 forward operator)
                  → cosine K-NN against per-installation gallery

The physics-informed env prediction must operate at embedding level, not raw level. AETHER does position-invariance; predicted-env removes the remaining room-shift component.

Privacy constraints (R14 + R15 + ADR-106/107)

Cross-room re-ID is a powerful biometric. The loop's privacy framework enforces:

1. No cross-installation linkage — each install has its own embedding space
2. Storage requires explicit opt-in (biometric-class consent)
3. Cryptographically verifiable forgetting of raw primitives
4. No re-ID across legal entities (hard-walled)

ADR-107 Layer 5 (per-installation embedding-space rotation key) enforces these technically.

See also

• Research notes: docs/research/sota-2026-05-22/R3-*.md, R3_1-*.md, R3_2-*.md
• ADRs: ADR-024 (AETHER), ADR-027 (MERIDIAN), ADR-106 (DP+isolation), ADR-107 (cross-install)
• Composes with: 01-physics-floor/ (R6.1 forward operator)