Casambi Web Controller

Local Casambi BLE lighting control exposed as an HTTP API. Compatible with matter_webcontrol v0.25.0+ federation, so a Casambi network can be merged into a Matter fabric as a logical bridge.

Architecture

FastAPI middleware over the casambi-bt library. The server discovers a Casambi network over BLE, authenticates with the network password, and exposes each unit through a REST API that matches matter_webcontrol's federation contract — so federation peers call /api/devices, /api/level, /api/mired, /api/set directly without embedded scripts (no RCE surface).

┌──────────────┐    HTTP+API key    ┌──────────────────┐    BLE    ┌──────────┐
│ matter-srv   │ ─────────────────▶ │ casambi-srv      │ ────────▶ │ Casambi  │
│ (Matter      │                    │ (this project)   │           │ network  │
│  fabric)     │ ◀─── /api/devices  │ FastAPI + bleak  │ ◀──notif─ │          │
└──────────────┘                    └──────────────────┘           └──────────┘

Limitations

• Single Casambi network per server instance (uses devices[0] from discovery).
• Lighting units only — sensor / occupancy not exposed.
• BLE depends on host OS permissions (on macOS, grant Bluetooth to the parent process via System Settings → Privacy & Security → Bluetooth).

Install

pip install -e .            # from source
# or
pip install casambi-web-controller   # from PyPI

Run

casambi-srv --port 8000 --api-key <secret>
# or via env:
CASAMBI_NETWORK_PWD=<network-password> CASAMBI_SRV_KEY=<secret> casambi-srv --port 8000

CLI options:

Password resolution order: --password flag → $CASAMBI_NETWORK_PWD env var → interactive getpass prompt. The env var is preferred over --password because CLI args are visible to other users via ps. Whichever source supplies it, the value is held only on app.state and the env var is pop()'d so it does not leak via /proc/PID/environ.

Federation with matter_webcontrol

Once both servers are running, register this server as a logical bridge on the Matter side:

GET http://<matter-host>:8080/api/bridge?ip=<casambi-host>&port=8000&api_key=<secret>

After this, every Casambi device appears under matter's /api/devices with id cas_* and is controllable through any matter endpoint (/api/level, /api/set, /api/toggle, etc.). Matter routes calls back through this server's REST API.

API endpoints

All endpoints require X-API-Key: <secret> if --api-key was set.

GET /api/devices

Federation device list. Each entry: {id, names, states}.

[
  {
    "id": "cas_d8dccdc7a8bc4f079f4e76d49bf9c7bc",
    "names": ["Sofa and Painting"],
    "states": {"on_off": false, "brightness_raw": 0}
  }
]

states keys (only emitted when the unit type supports the control):

• on_off (bool)
• brightness_raw (int 0–254, Matter scale)
• color_temp_mireds (int 153–500)

GET /api/lights

Light-only view with normalized fields.

[{"id": "cas_…", "names": ["…"], "on_off": true, "brightness": 0.78}]

GET /api/status

Summary counts.

{"lights_on": 1, "lights_off": 7, "sensors_active": 0, "logical_bridges": 0, "total_devices": 8}

GET|POST /api/level

Read or write Matter-scale level (0–254).

Body for POST: {"id": "cas_…", "level": 200}. Read-back response: {id, level}. Write response: {status, id, level, type}.

GET|POST /api/mired

Color temperature in mireds (153–500). Auto-clamped to per-unit Kelvin range. Returns 400 for units without temperature control.

Body for POST: {"id": "cas_…", "mireds": 250}.

GET|POST /api/set

Multi-attribute write. At least one of brightness / temperature is required (else 400).

Body for POST: {"id": "cas_…", "brightness": 0.5, "temperature": 4000}.

GET /api/toggle?id=

Flip on/off. When turning on, restores the last non-zero level (cached in-memory) instead of jumping to 100%.

GET /api/refresh

If BLE is connected, no-op (state is push-driven via Casambi notifications). If disconnected, attempts a reconnect using the cached network password.

GET /api/metadata

Declarative bridge metadata for federation discovery. No embedded Python scripts — peers consume the device list via /api/devices and call control endpoints directly.

{
  "bridge": {
    "id": "casambi_bridge_http",
    "type": "lighting_controller",
    "network_host": "192.168.1.220",
    "network_port": 8000,
    "api_version": "2"
  },
  "devices": [
    {
      "id": "cas_d8dccdc7a8bc4f079f4e76d49bf9c7bc",
      "name": "Sofa and Painting",
      "names": ["Sofa and Painting"],
      "hardware_type": "dimmable_light",
      "capabilities": ["on_off", "brightness"],
      "states": {"on_off": false, "brightness_raw": 0}
    }
  ]
}

Security notes

• X-API-Key comparison is constant-time (hmac.compare_digest) to resist timing attacks.
• The Casambi network password is held on app.state and not written into os.environ (no leak via /proc/PID/environ on Linux).
• Default bind is 127.0.0.1. Binding to 0.0.0.0 without --api-key logs a warning.
• /api/metadata no longer emits executable Python; the previous events.{name}.script shape was removed in v0.9.0 to match matter_webcontrol v0.25.0 (closes a federation RCE risk).

Compatibility matrix