--- name: ha-integration-patterns description: Home Assistant custom integration patterns and architectural decisions. Use when building HACS integrations, custom components, or API bridges for Home Assistant. Covers service response data, HTTP views, storage APIs, and integration architecture. ---

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.