Home Assistant Integration Patterns

Service Response Data Pattern

The Problem

By default, HA services are "fire-and-forget" and return empty arrays [].

The Solution (HA 2023.7+)

Register service with supports_response:

from homeassistant.helpers.service import SupportsResponse

hass.services.async_register(
    domain, 
    "get_full_config", 
    handle_get_full_config,
    schema=GET_CONFIG_SCHEMA,
    supports_response=SupportsResponse.ONLY,  # ← KEY PARAMETER
)

Call with ?return_response flag:

curl -X POST "$HA_URL/api/services/your_domain/get_full_config?return_response"

Response Handler

async def handle_get_full_config(hass: HomeAssistant, call: ServiceCall):
    """Handle the service call and return data."""
    # ... your logic ...
    return {"entities": entity_data, "automations": automation_data}

---

HTTP View vs Service: When to Use Each

Use Case	Use	Don't Use
Return complex data	HTTP View	Service (without response support)
Fire-and-forget actions	Service	HTTP View
Trigger automations	Service	HTTP View
Query state/config	HTTP View	Internal storage APIs

HTTP View Pattern

For data retrieval APIs:

from homeassistant.components.http import HomeAssistantView

class OpenClawConfigView(HomeAssistantView):
    """HTTP view for retrieving config."""
    url = "/api/openclaw/config"
    name = "api:openclaw:config"
    requires_auth = True

    async def get(self, request):
        hass = request.app["hass"]
        config = await get_config_data(hass)
        return json_response(config)

# Register in async_setup:
hass.http.register_view(OpenClawConfigView())

---

Critical: Avoid Internal APIs

Never use underscore-prefixed APIs — they're private and change between versions.

❌ Wrong:

storage_collection = hass.data["_storage_collection"]

✅ Right:

# Use public APIs only
from homeassistant.helpers.storage import Store
store = Store(hass, STORAGE_VERSION, STORAGE_KEY)

---

Storage Patterns

For Small Data (Settings, Cache)

from homeassistant.helpers.storage import Store

STORAGE_KEY = "your_domain.storage"
STORAGE_VERSION = 1

store = Store(hass, STORAGE_VERSION, STORAGE_KEY)

# Save
data = {"entities": modified_entities}
await store.async_save(data)

# Load
data = await store.async_load()

For Large Data (History, Logs)

Use external database or file storage, not HA storage helpers.

---

Breaking Changes to Watch

Change	Version	Migration
Conversation agents	2025.x+	Use async_process directly
Service response data	2023.7+	Add supports_response param
Config entry migration	2022.x+	Use async_migrate_entry

Always check: https://www.home-assistant.io/blog/ for your target version range.

---

HACS Integration Structure

custom_components/your_domain/
├── __init__.py          # async_setup_entry
├── config_flow.py       # UI configuration
├── manifest.json        # Dependencies, version
├── services.yaml        # Service definitions
└── storage_services.py  # Your storage logic

Minimal manifest.json

{
  "domain": "your_domain",
  "name": "Your Integration",
  "codeowners": ["@yourusername"],
  "config_flow": true,
  "dependencies": [],
  "requirements": [],
  "version": "1.0.0"
}

---

Testing Checklist

• Service calls return expected data (with ?return_response)
• HTTP views accessible with auth token
• No underscore-prefixed API usage
• Storage persists across restarts
• Config flow creates config entry
• Error handling returns meaningful messages

---

Documentation Resources

• Integration basics: developers.home-assistant.io/docs/creating_integration_index
• Service calls: developers.home-assistant.io/docs/dev_101_services
• HTTP views: developers.home-assistant.io/docs/api/webserver
• Breaking changes: home-assistant.io/blog/ (filter by version)
• HACS guidelines: hacs.xyz/docs/publish/start

---

Lesson Learned

From HA-OpenClaw Bridge attempt:

"80% of our issues were discoverable with 30-60 minutes of upfront docs reading. We jumped straight to coding based on assumptions rather than reading how HA actually works."

Use skills/pre-coding-research/ methodology before starting.