Home Assistant Integration Development

Home Assistant Integration Development

Create professional-grade custom Home Assistant integrations with complete config flows and entity implementations.

⚠️ BEFORE YOU START

This skill prevents 8 common integration errors and saves ~40% implementation time.

Known Issues This Skill Prevents

1. Missing manifest.json dependencies - Forgetting to declare required Home Assistant components
2. Async/​await issues - Not properly awaiting coordinator updates and entity initialization
3. Entity state class mismatches - Using wrong STATE_CLASS (measurement vs total) for sensor platforms
4. Config flow schema errors - Invalid vol.Schema definitions causing validation failures
5. Device info not linked - Entities created without proper device registry connections
6. Coordinator errors - Not handling data update failures gracefully
7. Platform import timing - Loading platform files before component initialization
8. Missing unique ID generation - Creating duplicate entities across restarts

Quick Start

Step 1: Create manifest.json

{
  "domain": "my_integration",
  "name": "My Integration",
  "codeowners": ["@username"],
  "config_flow": true,
  "documentation": "https://github.com/​username/​ha-my-integration",
  "requirements": [],
  "version": "0.0.1"
}

Why this matters: The manifest.json defines integration metadata, declares dependencies, and enables config flow UI in Home Assistant.

Step 2: Create init.py with async setup

import asyncio
from homeassistant.config_entries import ConfigEntry
from homeassistant.core import HomeAssistant
from homeassistant.exceptions import ConfigEntryNotReady

from .coordinator import MyDataUpdateCoordinator

DOMAIN = "my_integration"

async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
    """Set up the integration from config entry."""
    hass.data.setdefault(DOMAIN, {})

    # Create coordinator
    coordinator = MyDataUpdateCoordinator(hass, entry)
    await coordinator.async_config_entry_first_refresh()

    hass.data[DOMAIN][entry.entry_id] = coordinator

    # Forward setup to platforms
    await hass.config_entries.async_forward_entry_setups(entry, ["sensor"])

    return True

async def async_unload_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
    """Unload the integration."""
    unload_ok = await hass.config_entries.async_unload_platforms(entry, ["sensor"])
    if unload_ok:
        hass.data[DOMAIN].pop(entry.entry_id)
    return unload_ok

Why this matters: Proper async initialization ensures Home Assistant waits for data loading and platform setup completes before continuing.

Step 3: Create config_flow.py with validation

from typing import Any, Dict, Optional
import voluptuous as vol
from homeassistant.config_entries import ConfigFlow, ConfigEntry
from homeassistant.core import callback
from homeassistant.data_entry_flow import FlowResult

from .const import DOMAIN

class MyIntegrationConfigFlow(ConfigFlow, domain=DOMAIN):
    """Handle config flow for my_integration."""

    async def async_step_user(self, user_input: Optional[Dict[str, Any]] = None) -> FlowResult:
        """Handle user initiation of config flow."""
        errors = {}

        if user_input is not None:
            # Validate user input
            try:
                # Validate connection or API call
                pass
            except Exception as exc:
                errors["base"] = "invalid_auth"

            if not errors:
                # Create unique entry
                await self.async_set_unique_id(user_input.get("host"))
                self._abort_if_unique_id_configured()

                return self.async_create_entry(
                    title=user_input.get("name"),
                    data=user_input
                )

        # Show form
        return self.async_show_form(
            step_id="user",
            data_schema=vol.Schema({
                vol.Required("name"): str,
                vol.Required("host"): str,
            }),
            errors=errors
        )

    @staticmethod
    @callback
    def async_get_options_flow(config_entry: ConfigEntry):
        """Return options flow for this integration."""
        return MyIntegrationOptionsFlow(config_entry)

Why this matters: Config flows provide user-friendly setup UI and validate input before creating config entries.

Critical Rules

✅ Always Do

• ✅ Use async/​await throughout (async_setup_entry, async_added_to_hass, async_update_data)
• ✅ Generate unique_id for each entity (prevents duplicates on restart)
• ✅ Link entities to devices via device_info property
• ✅ Handle coordinator update failures gracefully (log, mark unavailable)
• ✅ Declare all external dependencies in manifest.json requirements
• ✅ Use type hints for better IDE support and Home Assistant compliance
• ✅ Register entities via coordinator patterns (DataUpdateCoordinator)

❌ Never Do

• ❌ Use synchronous network calls (requests library) - use aiohttp
• ❌ Import platform files at component level - let Home Assistant forward setup
• ❌ Create entities without unique_id - causes duplicates on restart
• ❌ Ignore coordinator update failures - mark entities unavailable
• ❌ Hardcode API endpoints - use config flow to store them
• ❌ Forget device_info when implementing multi-device integrations
• ❌ Use STATE_CLASS incorrectly (measurement vs total vs total_increasing)

Common Mistakes

❌ Wrong:

# Synchronous network call - blocks event loop
import requests
data = requests.get("https://api.example.com/​data").json()

# No unique_id - duplicate entities on restart
class MySensor(SensorEntity):
    pass

# Missing await
coordinator.async_refresh()

✅ Correct:

# Async network call - doesn't block
async with aiohttp.ClientSession() as session:
    async with session.get("https://api.example.com/​data") as resp:
        data = await resp.json()

# Proper unique_id generation
class MySensor(SensorEntity):
    @property
    def unique_id(self) -> str:
        return f"{self.coordinator.data['id']}_sensor"

# Proper await
await coordinator.async_request_refresh()

Why: Synchronous calls block Home Assistant's event loop, causing UI freezes. Missing unique_id causes entity duplicates. Missing await means code continues before async operation completes.

Known Issues Prevention

Manifest Configuration Reference

manifest.json

{
  "domain": "integration_name",
  "name": "Integration Display Name",
  "codeowners": ["@github_username"],
  "config_flow": true,
  "documentation": "https://github.com/​username/​repo",
  "homeassistant": "2024.1.0",
  "requirements": ["requests>=2.25.0"],
  "version": "1.0.0",
  "issue_tracker": "https://github.com/​username/​repo/​issues"
}

Key settings:

• domain: Unique identifier (alphanumeric, underscores, lowercase)
• config_flow: Set to true to enable config UI
• requirements: List of PyPI packages needed (e.g., ["requests>=2.25.0"])
• homeassistant: Minimum Home Assistant version required

Config Flow Patterns

Schema with vol.All for validation

vol.Schema({
    vol.Required("host"): vol.All(str, vol.Length(min=5)),
    vol.Required("port", default=8080): int,
    vol.Optional("api_key"): str,
})

Reauth flow for expired credentials

async def async_step_reauth(self, user_input: Dict[str, Any] | None = None) -> FlowResult:
    """Handle reauth upon an API authentication error."""
    config_entry = self.hass.config_entries.async_get_entry(
        self.context["entry_id"]
    )

    if user_input is not None:
        config_entry.data = {**config_entry.data, **user_input}
        self.hass.config_entries.async_update_entry(config_entry)
        return self.async_abort(reason="reauth_successful")

    return self.async_show_form(
        step_id="reauth",
        data_schema=vol.Schema({vol.Required("api_key"): str})
    )

Entity Implementation Patterns

Sensor with State Class

from homeassistant.components.sensor import SensorEntity, SensorStateClass
from homeassistant.const import UnitOfTemperature

class TemperatureSensor(SensorEntity):
    """Temperature sensor entity."""

    _attr_device_class = "temperature"
    _attr_state_class = SensorStateClass.MEASUREMENT
    _attr_native_unit_of_measurement = UnitOfTemperature.CELSIUS

    def __init__(self, coordinator, idx):
        """Initialize sensor."""
        self.coordinator = coordinator
        self._idx = idx

    @property
    def unique_id(self) -> str:
        """Return unique ID."""
        return f"{self.coordinator.data['id']}_temp_{self._idx}"

    @property
    def device_info(self) -> DeviceInfo:
        """Return device information."""
        return DeviceInfo(
            identifiers={(DOMAIN, self.coordinator.data['id'])},
            name=self.coordinator.data['name'],
            manufacturer="My Company",
        )

    @property
    def native_value(self) -> float | None:
        """Return sensor value."""
        try:
            return float(self.coordinator.data['temperature'])
        except (KeyError, TypeError):
            return None

    async def async_added_to_hass(self) -> None:
        """Connect to coordinator when added."""
        await super().async_added_to_hass()
        self.async_on_remove(
            self.coordinator.async_add_listener(self._handle_coordinator_update)
        )

    @callback
    def _handle_coordinator_update(self) -> None:
        """Update when coordinator updates."""
        self.async_write_ha_state()

Binary Sensor

from homeassistant.components.binary_sensor import BinarySensorEntity, BinarySensorDeviceClass

class MotionSensor(BinarySensorEntity):
    """Motion detection sensor."""

    _attr_device_class = BinarySensorDeviceClass.MOTION

    @property
    def is_on(self) -> bool | None:
        """Return True if motion detected."""
        return self.coordinator.data.get('motion', False)

DataUpdateCoordinator Pattern

from datetime import timedelta
from homeassistant.helpers.update_coordinator import (
    DataUpdateCoordinator,
    UpdateFailed,
)
import logging

_LOGGER = logging.getLogger(__name__)

class MyDataUpdateCoordinator(DataUpdateCoordinator):
    """Coordinator for fetching data."""

    def __init__(self, hass, entry):
        """Initialize coordinator."""
        super().__init__(
            hass,
            _LOGGER,
            name="My Integration",
            update_interval=timedelta(minutes=5),
        )
        self.entry = entry

    async def _async_update_data(self):
        """Fetch data from API."""
        try:
            async with aiohttp.ClientSession() as session:
                async with session.get(
                    f"https://api.example.com/​data",
                    headers={"Authorization": f"Bearer {self.entry.data['api_key']}"}
                ) as resp:
                    if resp.status == 401:
                        raise ConfigEntryAuthFailed("Invalid API key")
                    return await resp.json()
        except asyncio.TimeoutError as err:
            raise UpdateFailed("API timeout") from err
        except Exception as err:
            raise UpdateFailed(f"API error: {err}") from err

Device Registry Patterns

Creating device with identifiers

from homeassistant.helpers.device_registry import DeviceInfo

device_info = DeviceInfo(
    identifiers={(DOMAIN, "device_unique_id")},
    name="Device Name",
    manufacturer="Manufacturer",
    model="Model Name",
    sw_version="1.0.0",
    via_device=(DOMAIN, "parent_device_id"),  # For child devices
)

Serial number and connections

device_info = DeviceInfo(
    identifiers={(DOMAIN, device_id)},
    serial_number="SERIAL123",
    connections={(dr.CONNECTION_NETWORK_MAC, "aa:bb:cc:dd:ee:ff")},
)

Common Patterns

Loading config from config entry

class MyIntegration:
    def __init__(self, hass: HomeAssistant, entry: ConfigEntry):
        self.hass = hass
        self.entry = entry
        self.api_key = entry.data.get("api_key")
        self.host = entry.data.get("host")

Handling options flow

async def async_step_init(self, user_input: Optional[Dict[str, Any]] = None) -> FlowResult:
    """Manage integration options."""
    if user_input is not None:
        return self.async_create_entry(
            title="",
            data=user_input
        )

    current_options = self.config_entry.options
    return self.async_show_form(
        step_id="init",
        data_schema=vol.Schema({
            vol.Optional("refresh_rate", default=current_options.get("refresh_rate", 5)): int,
        })
    )

Bundled Resources

References

Located in references/:

• manifest-reference.md - Complete manifest.json field reference
• entity-base-classes.md - Entity implementation base classes and properties
• config-flow-patterns.md - Advanced config flow patterns and validation

Templates

Located in assets/:

• manifest.json - Starter manifest.json template
• config_flow.py - Basic config flow boilerplate
• __init__.py - Component initialization template
• coordinator.py - DataUpdateCoordinator template

Note: For deep dives on specific topics, see the reference files above.

Dependencies

Required

Optional

Official Documentation

• Creating a Component - Home Assistant Developers
• Config Entries - Home Assistant Developers
• Entity Index - Home Assistant Developers
• Device Registry - Home Assistant Developers

Troubleshooting

Entity appears multiple times after restart

Symptoms: Same sensor/​switch/​light appears 2+ times in Home Assistant after reboot

Solution:

# Add unique_id property to entity class
@property
def unique_id(self) -> str:
    return f"{self.coordinator.data['id']}_{self.platform}_{self._attr_name}"

Config flow validation never completes

Symptoms: Form hangs when submitting, no error displayed

Solution:

# Ensure all async operations are awaited and errors caught
async def async_step_user(self, user_input=None):
    errors = {}
    if user_input is not None:
        try:
            await self._validate_input(user_input)  # ← Add await
        except Exception as e:
            errors["base"] = "validation_error"  # ← Set error

        if not errors:
            return self.async_create_entry(...)

Entities show unavailable after update

Symptoms: All entities turn unavailable after coordinator update

Solution:

# Handle coordinator errors gracefully
async def _async_update_data(self):
    try:
        return await self.api.fetch_data()
    except Exception as err:
        raise UpdateFailed(f"Error: {err}") from err  # ← Raises UpdateFailed, not Exception

Device doesn't appear in device registry

Symptoms: Device created but not visible in Home Assistant devices

Solution:

# Ensure device_info is returned by ALL entities for the device
@property
def device_info(self) -> DeviceInfo:
    return DeviceInfo(
        identifiers={(DOMAIN, self.coordinator.data['id'])},  # ← Must be consistent
        name=self.coordinator.data['name'],
        manufacturer="Manufacturer",
    )

Setup Checklist

Before implementing a new integration, verify:

• Domain name is unique and follows lowercase-with-underscores convention
• manifest.json created with domain, name, and codeowners
• Config flow or manual configuration method implemented
• All async functions properly awaited
• Unique IDs generated for all entities (prevents duplicates)
• Device info linked if multi-device integration
• DataUpdateCoordinator or equivalent polling pattern
• Error handling with UpdateFailed exceptions
• Type hints on all function signatures
• Tests written for config flow validation
• Documentation URL in manifest points to valid location