feat: ADR-063/064 mmWave sensor fusion + multimodal ambient intelligence

docs/adr/ADR-063-mmwave-sensor-fusion.md

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+# ADR-063: 60 GHz mmWave Sensor Fusion with WiFi CSI
+
+**Status:** Proposed
+**Date:** 2026-03-15
+**Deciders:** @ruvnet
+**Related:** ADR-014 (SOTA signal processing), ADR-021 (vital sign extraction), ADR-029 (RuvSense multistatic), ADR-039 (edge intelligence), ADR-042 (CHCI coherent sensing)
+
+## Context
+
+RuView currently senses the environment using WiFi CSI — a passive technique that analyzes how WiFi signals are disturbed by human presence and movement. While this works through walls and requires no line of sight, CSI-derived vital signs (breathing rate, heart rate) are inherently noisy because they rely on phase extraction from multipath-rich WiFi channels.
+
+A complementary sensing modality exists: **60 GHz mmWave radar** modules (e.g., Seeed MR60BHA2) that use active FMCW radar at 60 GHz to measure breathing and heart rate with clinical-grade accuracy. These modules are inexpensive (~$15), run on ESP32-C6/C3, and output structured vital signs over UART.
+
+**Live hardware capture (COM4, 2026-03-15)** from a Seeed MR60BHA2 on an ESP32-C6 running ESPHome:
+
+```
+[D][sensor:093]: 'Real-time respiratory rate': Sending state 22.00000
+[D][sensor:093]: 'Real-time heart rate': Sending state 92.00000 bpm
+[D][sensor:093]: 'Distance to detection object': Sending state 0.00000 cm
+[D][sensor:093]: 'Target Number': Sending state 0.00000
+[D][binary_sensor:036]: 'Person Information': Sending state OFF
+[D][sensor:093]: 'Seeed MR60BHA2 Illuminance': Sending state 0.67913 lx
+```
+
+### The Opportunity
+
+Fusing WiFi CSI with mmWave radar creates a sensor system that is greater than the sum of its parts:
+
+| Capability | WiFi CSI Alone | mmWave Alone | Fused |
+|-----------|---------------|-------------|-------|
+| Through-wall sensing | Yes (5m+) | No (LoS only, ~3m) | Yes — CSI for room-scale, mmWave for precision |
+| Heart rate accuracy | ±5-10 BPM | ±1-2 BPM | ±1-2 BPM (mmWave primary, CSI cross-validates) |
+| Breathing accuracy | ±2-3 BPM | ±0.5 BPM | ±0.5 BPM |
+| Presence detection | Good (adaptive threshold) | Excellent (range-gated) | Excellent + through-wall |
+| Multi-person | Via subcarrier clustering | Via range-Doppler bins | Combined spatial + RF resolution |
+| Fall detection | Phase acceleration | Range/velocity + micro-Doppler | Dual-confirm reduces false positives to near-zero |
+| Pose estimation | Via trained model | Not available | CSI provides pose; mmWave provides ground-truth vitals for training |
+| Coverage | Whole room (passive) | ~120° cone, 3m range | Full room + precision zone |
+| Cost per node | ~$9 (ESP32-S3) | ~$15 (ESP32-C6 + MR60BHA2) | ~$24 combined |
+
+### RuVector Integration Points
+
+The RuVector v2.0.4 stack (already integrated per ADR-016) provides the signal processing backbone:
+
+| RuVector Component | Role in mmWave Fusion |
+|-------------------|----------------------|
+| `ruvector-attention` (`bvp.rs`) | Blood Volume Pulse estimation — mmWave heart rate can calibrate the WiFi CSI BVP phase extraction |
+| `ruvector-temporal-tensor` (`breathing.rs`) | Breathing rate estimation — mmWave provides ground-truth for adaptive filter tuning |
+| `ruvector-solver` (`triangulation.rs`) | Multilateration — mmWave range-gated distance + CSI amplitude = 3D position |
+| `ruvector-attn-mincut` (`spectrogram.rs`) | Time-frequency decomposition — mmWave Doppler complements CSI phase spectrogram |
+| `ruvector-mincut` (`metrics.rs`, DynamicPersonMatcher) | Multi-person association — mmWave target IDs help disambiguate CSI subcarrier clusters |
+
+### RuvSense Integration Points
+
+The RuvSense multistatic sensing pipeline (ADR-029) gains new capabilities:
+
+| RuvSense Module | mmWave Integration |
+|----------------|-------------------|
+| `pose_tracker.rs` (AETHER re-ID) | mmWave distance + velocity as additional re-ID features for Kalman tracker |
+| `longitudinal.rs` (Welford stats) | mmWave vitals as reference signal for CSI drift detection |
+| `intention.rs` (pre-movement) | mmWave micro-Doppler detects pre-movement 100-200ms earlier than CSI |
+| `adversarial.rs` (consistency check) | mmWave provides independent signal to detect CSI spoofing/anomalies |
+| `coherence_gate.rs` | mmWave presence as additional gate input — if mmWave says "no person", CSI coherence gate rejects |
+
+### Cross-Viewpoint Fusion Integration
+
+The viewpoint fusion pipeline (`ruvector/src/viewpoint/`) extends naturally:
+
+| Viewpoint Module | mmWave Extension |
+|-----------------|-----------------|
+| `attention.rs` (CrossViewpointAttention) | mmWave range becomes a new "viewpoint" in the attention mechanism |
+| `geometry.rs` (GeometricDiversityIndex) | mmWave cone geometry contributes to Fisher Information / Cramer-Rao bounds |
+| `coherence.rs` (phase phasor) | mmWave phase coherence as validation for WiFi phasor coherence |
+| `fusion.rs` (MultistaticArray) | mmWave node becomes a member of the multistatic array with its own domain events |
+
+## Decision
+
+Add 60 GHz mmWave radar sensor support to the RuView firmware and sensing pipeline with auto-detection and device-specific capabilities.
+
+### Architecture
+
+```
+┌─────────────────────────────────────────────────────────┐
+│                    Sensing Node                          │
+│                                                          │
+│  ┌──────────────┐    ┌──────────────┐    ┌────────────┐ │
+│  │ ESP32-S3     │    │ ESP32-C6     │    │ Combined   │ │
+│  │ WiFi CSI     │    │ + MR60BHA2   │    │ S3 + UART  │ │
+│  │ (COM7)       │    │ 60GHz mmWave │    │ mmWave     │ │
+│  │              │    │ (COM4)       │    │            │ │
+│  │ Passive      │    │ Active radar │    │ Both modes │ │
+│  │ Through-wall │    │ LoS, precise │    │            │ │
+│  └──────┬───────┘    └──────┬───────┘    └─────┬──────┘ │
+│         │                    │                   │       │
+│         └────────┬───────────┘                   │       │
+│                  ▼                               │       │
+│         ┌────────────────┐                       │       │
+│         │ Fusion Engine  │◄──────────────────────┘       │
+│         │                │                               │
+│         │ • Kalman fuse  │  Vitals packet (extended):    │
+│         │ • Cross-validate│  magic 0xC5110004             │
+│         │ • Ground-truth │  + mmwave_hr, mmwave_br       │
+│         │   calibration  │  + mmwave_distance             │
+│         │ • Fall confirm │  + mmwave_target_count         │
+│         └────────────────┘  + confidence scores           │
+└─────────────────────────────────────────────────────────┘
+```
+
+### Three Deployment Modes
+
+**Mode 1: Standalone CSI (existing)** — ESP32-S3 only, WiFi CSI sensing.
+
+**Mode 2: Standalone mmWave** — ESP32-C6 + MR60BHA2, precise vitals in a single room.
+
+**Mode 3: Fused (recommended)** — ESP32-S3 + mmWave module on UART, or two separate nodes with server-side fusion.
+
+### Auto-Detection Protocol
+
+The firmware will auto-detect connected mmWave modules at boot:
+
+1. **UART probe** — On configured UART pins, send the MR60BHA2 identification command (`0x01 0x01 0x00 0x01 ...`) and check for valid response header
+2. **Protocol detection** — Identify the sensor family:
+   - Seeed MR60BHA2 (breathing + heart rate)
+   - Seeed MR60FDA1 (fall detection)
+   - Seeed MR24HPC1 (presence + light sleep/deep sleep)
+   - HLK-LD2410 (presence + distance)
+   - HLK-LD2450 (multi-target tracking)
+3. **Capability registration** — Register detected sensor capabilities in the edge config:
+
+```c
+typedef struct {
+    uint8_t  mmwave_detected;      /** 1 if mmWave module found on UART */
+    uint8_t  mmwave_type;          /** Sensor family (MR60BHA2, MR60FDA1, etc.) */
+    uint8_t  mmwave_has_hr;        /** Heart rate capability */
+    uint8_t  mmwave_has_br;        /** Breathing rate capability */
+    uint8_t  mmwave_has_fall;      /** Fall detection capability */
+    uint8_t  mmwave_has_presence;  /** Presence detection capability */
+    uint8_t  mmwave_has_distance;  /** Range measurement capability */
+    uint8_t  mmwave_has_tracking;  /** Multi-target tracking capability */
+    float    mmwave_hr_bpm;        /** Latest heart rate from mmWave */
+    float    mmwave_br_bpm;        /** Latest breathing rate from mmWave */
+    float    mmwave_distance_cm;   /** Distance to nearest target */
+    uint8_t  mmwave_target_count;  /** Number of detected targets */
+    bool     mmwave_person_present;/** mmWave presence state */
+} mmwave_state_t;
+```
+
+### Supported Sensors
+
+| Sensor | Frequency | Capabilities | UART Protocol | Cost |
+|--------|-----------|-------------|---------------|------|
+| **Seeed MR60BHA2** | 60 GHz | HR, BR, presence, illuminance | Seeed proprietary frames | ~$15 |
+| **Seeed MR60FDA1** | 60 GHz | Fall detection, presence | Seeed proprietary frames | ~$15 |
+| **Seeed MR24HPC1** | 24 GHz | Presence, sleep stage, distance | Seeed proprietary frames | ~$10 |
+| **HLK-LD2410** | 24 GHz | Presence, distance (motion + static) | HLK binary protocol | ~$3 |
+| **HLK-LD2450** | 24 GHz | Multi-target tracking (x,y,speed) | HLK binary protocol | ~$5 |
+
+### Fusion Algorithms
+
+**1. Vital Sign Fusion (Kalman filter)**
+```
+mmWave HR (high confidence, 1 Hz) ─┐
+                                    ├─► Kalman fuse → fused HR ± confidence
+CSI-derived HR (lower confidence)  ─┘
+```
+
+**2. Fall Detection (dual-confirm)**
+```
+CSI phase accel > thresh ──────┐
+                               ├─► AND gate → confirmed fall (near-zero false positives)
+mmWave range-velocity pattern ─┘
+```
+
+**3. Presence Validation**
+```
+CSI adaptive threshold ────┐
+                           ├─► Weighted vote → robust presence
+mmWave target count > 0 ──┘
+```
+
+**4. Training Calibration**
+```
+mmWave ground-truth vitals → train CSI BVP extraction model
+mmWave distance → calibrate CSI triangulation
+mmWave micro-Doppler → label CSI activity patterns
+```
+
+### Vitals Packet Extension
+
+Extend the existing 32-byte vitals packet (magic `0xC5110002`) with a new 48-byte fused packet:
+
+```c
+typedef struct __attribute__((packed)) {
+    /* Existing 32-byte vitals fields */
+    uint32_t magic;            /* 0xC5110004 (fused vitals) */
+    uint8_t  node_id;
+    uint8_t  flags;            /* Bit0=presence, Bit1=fall, Bit2=motion, Bit3=mmwave_present */
+    uint16_t breathing_rate;   /* Fused BPM * 100 */
+    uint32_t heartrate;        /* Fused BPM * 10000 */
+    int8_t   rssi;
+    uint8_t  n_persons;
+    uint8_t  mmwave_type;      /* Sensor type enum */
+    uint8_t  fusion_confidence;/* 0-100 fusion quality score */
+    float    motion_energy;
+    float    presence_score;
+    uint32_t timestamp_ms;
+    /* New mmWave fields (16 bytes) */
+    float    mmwave_hr_bpm;    /* Raw mmWave heart rate */
+    float    mmwave_br_bpm;    /* Raw mmWave breathing rate */
+    float    mmwave_distance;  /* Distance to nearest target (cm) */
+    uint8_t  mmwave_targets;   /* Target count */
+    uint8_t  mmwave_confidence;/* mmWave signal quality 0-100 */
+    uint16_t reserved;
+} edge_fused_vitals_pkt_t;
+
+_Static_assert(sizeof(edge_fused_vitals_pkt_t) == 48, "fused vitals must be 48 bytes");
+```
+
+### NVS Configuration
+
+New provisioning parameters:
+
+```bash
+python provision.py --port COM7 \
+  --mmwave-uart-tx 17 --mmwave-uart-rx 18 \  # UART pins for mmWave module
+  --mmwave-type auto \                         # auto-detect, or: mr60bha2, ld2410, etc.
+  --fusion-mode kalman \                       # kalman, vote, mmwave-primary, csi-primary
+  --fall-dual-confirm true                     # require both CSI + mmWave for fall alert
+```
+
+### Implementation Phases
+
+| Phase | Scope | Effort |
+|-------|-------|--------|
+| **Phase 1** | UART driver + MR60BHA2 parser + auto-detection | 2 weeks |
+| **Phase 2** | Fused vitals packet + Kalman vital sign fusion | 1 week |
+| **Phase 3** | Dual-confirm fall detection + presence voting | 1 week |
+| **Phase 4** | HLK-LD2410/LD2450 support + multi-target fusion | 2 weeks |
+| **Phase 5** | RuVector calibration pipeline (mmWave as ground truth) | 3 weeks |
+| **Phase 6** | Server-side fusion for separate CSI + mmWave nodes | 2 weeks |
+
+## Consequences
+
+### Positive
+- Near-zero false positive fall detection (dual-confirm)
+- Clinical-grade vital signs when mmWave is present, with CSI as fallback
+- Self-calibrating CSI pipeline using mmWave ground truth
+- Backward compatible — existing CSI-only nodes work unchanged
+- Low incremental cost (~$3-15 per mmWave module)
+- Auto-detection means zero configuration for supported sensors
+- RuVector attention/solver/temporal-tensor modules gain a high-quality reference signal
+
+### Negative
+- Added firmware complexity (~2-3 KB RAM for mmWave state + UART buffer)
+- mmWave modules require line-of-sight (complementary to CSI, not replacement)
+- Multiple UART protocols to maintain (Seeed, HLK families)
+- 48-byte fused packet requires server parser update
+
+### Neutral
+- ESP32-C6 cannot run the full CSI pipeline (single-core RISC-V) but can serve as a dedicated mmWave bridge node
+- mmWave modules add ~15 mA power draw per node