Spaxel

WiFi CSI-based indoor positioning for self-hosted homes.

Spaxel detects and localizes people in a home using WiFi Channel State Information — no cameras, no microphones, no cloud. A single Docker container (the "mothership") runs on a home server and manages a fleet of ESP32-S3 nodes that capture and stream CSI over WiFi. The mothership fuses CSI from all links to detect presence, follow motion, and — with enough nodes — estimate 2D/3D position, rendered on a Three.js floor-plan dashboard.

Everything runs locally on hardware you own. There is no cloud relay, no account, and no RF beyond the 2.4 GHz WiFi already in your home.

What it can realistically do

Based on physics and the research in docs/research/ (see docs/research/06-accuracy-and-limits.md):

• Presence detection — reliably, with 2+ nodes on opposite sides of a space
• Approximate 2D position — ±0.5–1.0 m with 4+ nodes
• Motion / trajectory tracking — follows moving people
• Rough person count — distinguishes 1 vs. 2+ (degrades at 3+)
• Rough Z-axis — ±1–2 m with mixed-height node placement (enables fall detection)
• Stationary-person detection — via breathing micro-motion (0.1–0.5 Hz)

Not achievable with 2.4 GHz CSI: sub-10 cm accuracy, skeletal pose, reliable 5+ person tracking.

Privacy by design

Spaxel is CSI-only — it never captures camera images or audio. Detection is local: data stays on the mothership, there is no cloud relay or remote access, and no user accounts are required (a single PIN protects the dashboard). See the Non-Goals section of docs/plan/plan.md.

Repository layout

Spaxel is a Go workspace of three modules, plus ESP32 firmware and a static frontend:

Path	Description
mothership/	Go backend — ingestion, signal pipeline, localizer, fleet manager, REST/WebSocket API, dashboard server (github.com/spaxel/mothership)
cmd/sim/	spaxel-sim — CSI/node simulator CLI for hardware-free development and integration tests (github.com/spaxel/sim)
test/acceptance/	Acceptance-test module (AS-1 … AS-7), driven by the simulator
firmware/	ESP-IDF (C) firmware for the ESP32-S3 node fleet
dashboard/	Vanilla JS + Three.js single-page UI (see dashboard/README.md)
docs/	Plan, notes, and research (see Documentation below)
Dockerfile, docker-compose.yml	Single-container packaging
PROGRESS.md, VERSION	Implementation status and current version

Quickstart

The mothership ships as a single container, published as ronaldraygun/spaxel. The bundled docker-compose.yml builds from source by default and exposes one port (8080).

git clone https://github.com/jedarden/spaxel.git
cd spaxel
docker compose up -d        # builds the mothership image, host networking
# …or skip the build and use the published image:
#   docker pull ronaldraygun/spaxel

Then open http://<server-ip>:8080, set a dashboard PIN, and use Add Node (Chrome/Edge Web Serial) to provision an ESP32-S3 over USB. The node discovers the mothership via mDNS and begins streaming CSI — zero manual IP configuration.

network_mode: host is required for mDNS multicast to reach ESP32 nodes on your LAN. If host networking isn't available, set SPAXEL_MDNS_ENABLED=false and provision nodes with a manual mothership IP (see docs/notes/mdns-override.md).

Key environment variables

Variable	Default	Purpose
SPAXEL_BIND_ADDR	0.0.0.0:8080	Listen address (set to 127.0.0.1:8080 behind a local reverse proxy)
SPAXEL_DATA_DIR	/data	Persistent storage: SQLite, baselines, floor plans, CSI replay buffer, firmware
SPAXEL_MQTT_BROKER	(unset)	Optional MQTT broker URL for Home Assistant integration (e.g. mqtt://homeassistant.local:1883)
TZ	UTC	Timezone for diurnal baselines, briefings, and quiet hours (IANA name)
SPAXEL_MDNS_ENABLED	true	Disable when not using host networking

The full list is in the Deployment section of docs/plan/plan.md.

Building & developing

# Mothership backend
cd mothership && go test ./... && go vet ./...

# CSI / node simulator
go build -o spaxel-sim ./cmd/sim

# Hardware-free acceptance suite (no ESP32 needed)
cd test/acceptance && go test ./...

# Dashboard unit + accessibility tests
cd dashboard && npm test && npm run test:a11y

Firmware is built with ESP-IDF 5.2.x — see the Firmware Build System section of the plan.

Documentation

• docs/plan/plan.md — the complete design: architecture, components, schema, deployment, phases
• docs/notes/ — implementation notes (recovery mechanisms, mDNS override, simulation testing, UX)
• docs/research/ — CSI fundamentals, physics, algorithms, accuracy limits, prior-art papers
• dashboard/README.md — dashboard test setup (Jest, axe-core + Playwright)
• PROGRESS.md — phase-by-phase implementation status

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Spaxel is self-hosted, CSI-only, and cloud-free by design.