Home Assistant Core Skill

Core Home Assistant API integration patterns, authentication, and entity management.

Activation Triggers

Activate this skill when working with:

• Home Assistant REST API
• WebSocket API connections
• Entity state management
• Service calls
• Event bus subscriptions

Authentication

Long-Lived Access Token

import httpx

class HAClient:
    def __init__(self, url: str, token: str):
        self.url = url.rstrip('/')
        self.headers = {
            "Authorization": f"Bearer {token}",
            "Content-Type": "application/json"
        }

    async def get_states(self) -> list:
        async with httpx.AsyncClient() as client:
            response = await client.get(
                f"{self.url}/api/states",
                headers=self.headers
            )
            response.raise_for_status()
            return response.json()

    async def get_state(self, entity_id: str) -> dict:
        async with httpx.AsyncClient() as client:
            response = await client.get(
                f"{self.url}/api/states/{entity_id}",
                headers=self.headers
            )
            response.raise_for_status()
            return response.json()

    async def call_service(
        self,
        domain: str,
        service: str,
        data: dict = None,
        target: dict = None
    ) -> dict:
        payload = {}
        if data:
            payload.update(data)
        if target:
            payload["target"] = target

        async with httpx.AsyncClient() as client:
            response = await client.post(
                f"{self.url}/api/services/{domain}/{service}",
                headers=self.headers,
                json=payload
            )
            response.raise_for_status()
            return response.json()

TypeScript Client

interface HAState {
  entity_id: string;
  state: string;
  attributes: Record<string, any>;
  last_changed: string;
  last_updated: string;
}

class HomeAssistantClient {
  private url: string;
  private token: string;

  constructor(url: string, token: string) {
    this.url = url.replace(/\/$/, '');
    this.token = token;
  }

  private get headers(): HeadersInit {
    return {
      'Authorization': `Bearer ${this.token}`,
      'Content-Type': 'application/json'
    };
  }

  async getStates(): Promise<HAState[]> {
    const response = await fetch(`${this.url}/api/states`, {
      headers: this.headers
    });
    if (!response.ok) throw new Error(`HTTP ${response.status}`);
    return response.json();
  }

  async callService(
    domain: string,
    service: string,
    data?: Record<string, any>,
    target?: { entity_id?: string | string[] }
  ): Promise<any> {
    const response = await fetch(
      `${this.url}/api/services/${domain}/${service}`,
      {
        method: 'POST',
        headers: this.headers,
        body: JSON.stringify({ ...data, target })
      }
    );
    if (!response.ok) throw new Error(`HTTP ${response.status}`);
    return response.json();
  }
}

WebSocket API

Real-Time State Updates

import asyncio
import json
import websockets

class HAWebSocket:
    def __init__(self, url: str, token: str):
        self.url = url.replace('http', 'ws') + '/api/websocket'
        self.token = token
        self.message_id = 0
        self.ws = None

    async def connect(self):
        self.ws = await websockets.connect(self.url)
        # Wait for auth_required
        await self.ws.recv()
        # Send auth
        await self.ws.send(json.dumps({
            "type": "auth",
            "access_token": self.token
        }))
        # Wait for auth_ok
        result = json.loads(await self.ws.recv())
        if result["type"] != "auth_ok":
            raise Exception("Authentication failed")

    async def subscribe_events(self, event_type: str = None):
        self.message_id += 1
        msg = {
            "id": self.message_id,
            "type": "subscribe_events"
        }
        if event_type:
            msg["event_type"] = event_type
        await self.ws.send(json.dumps(msg))
        return self.message_id

    async def subscribe_state_changes(self, entity_id: str = None):
        self.message_id += 1
        msg = {
            "id": self.message_id,
            "type": "subscribe_trigger",
            "trigger": {
                "platform": "state"
            }
        }
        if entity_id:
            msg["trigger"]["entity_id"] = entity_id
        await self.ws.send(json.dumps(msg))
        return self.message_id

    async def listen(self):
        async for message in self.ws:
            yield json.loads(message)

# Usage
async def monitor_states():
    ws = HAWebSocket("http://homeassistant.local:8123", "token")
    await ws.connect()
    await ws.subscribe_events("state_changed")

    async for event in ws.listen():
        if event.get("type") == "event":
            data = event["event"]["data"]
            print(f"{data['entity_id']}: {data['new_state']['state']}")

Entity Domains

Domain	Description	Common Services
light	Lighting control	turn_on, turn_off, toggle
switch	On/off switches	turn_on, turn_off, toggle
climate	HVAC systems	set_temperature, set_hvac_mode
cover	Blinds, doors	open, close, set_position
lock	Smart locks	lock, unlock
media_player	Media devices	play, pause, volume_set
fan	Fans	turn_on, set_speed
vacuum	Robot vacuums	start, stop, return_to_base
camera	Security cameras	snapshot, record
sensor	Sensors	(read-only)
binary_sensor	Binary sensors	(read-only)

Service Call Patterns

Light Control

# Turn on with brightness
await ha.call_service("light", "turn_on", {
    "brightness_pct": 75,
    "color_temp_kelvin": 4000,
    "transition": 2
}, target={"entity_id": "light.living_room"})

# RGB color
await ha.call_service("light", "turn_on", {
    "rgb_color": [255, 100, 50]
}, target={"entity_id": "light.accent"})

Climate Control

# Set temperature
await ha.call_service("climate", "set_temperature", {
    "temperature": 72,
    "hvac_mode": "heat"
}, target={"entity_id": "climate.thermostat"})

# Set preset
await ha.call_service("climate", "set_preset_mode", {
    "preset_mode": "away"
}, target={"entity_id": "climate.thermostat"})

Media Player

# Play media
await ha.call_service("media_player", "play_media", {
    "media_content_id": "spotify:playlist:abc123",
    "media_content_type": "playlist"
}, target={"entity_id": "media_player.living_room"})

# Volume control
await ha.call_service("media_player", "volume_set", {
    "volume_level": 0.5
}, target={"entity_id": "media_player.living_room"})

Error Handling

from httpx import HTTPStatusError

async def safe_service_call(ha, domain, service, data, target):
    try:
        result = await ha.call_service(domain, service, data, target)
        return {"success": True, "result": result}
    except HTTPStatusError as e:
        if e.response.status_code == 401:
            return {"success": False, "error": "Authentication failed"}
        elif e.response.status_code == 404:
            return {"success": False, "error": "Service or entity not found"}
        else:
            return {"success": False, "error": str(e)}
    except Exception as e:
        return {"success": False, "error": str(e)}

Best Practices

1. Use area and label targeting for group operations
2. Implement retry logic for network failures
3. Cache entity states to reduce API calls
4. Use WebSocket for real-time monitoring
5. Validate entity_ids before service calls
6. Handle unavailable states gracefully