Add Home Automation capability

[lewisthorpe1994]

Summary

Adds a Home Automation capability backed by a Home Assistant REST API adapter.

This includes:

• A backend protocol with normalized entity, state, service, service argument, and service-call result dataclasses.
• A HomeAutomation capability and HomeAutomationToolset exposing service discovery, entity/state inspection, and service calls to agents.
• A Home Assistant backend that validates /api/services and /api/states responses with Pydantic models, caches the service catalog, handles return_response service calls, and verifies service-call outcomes with changed states or follow-up state polling.
• Capability-local README documentation and tests covering the backend contract, Home Assistant response mapping, service calls, polling, and exports.

Linked Issue

Fixes #125

Checklist

• Linked issue exists and is referenced above
• Tests added/updated for new behavior
• make lint && make typecheck && make test passes locally (don't stress about CI -- we'll help)
• No changes to pyproject.toml or uv.lock (dependency changes require a separate issue)
• Docstrings use single backticks (not RST double backticks)

Local validation run:

• make lint
• make typecheck
• make testcov (123 passed, 100% coverage)

[lewisthorpe1994]

Also tested this manually against a local Home Assistant instance using Gemma via llama.cpp.

Prompt: “turn off the computer room light”

The agent flow was:

1. Called list_entities(domain='light')
2. Selected light.computer_room_light from the returned entities
3. Called call_service(domain='light', entity_id='light.computer_room_light', service_name='turn_off')
4. Received ServiceCallResult(..., verified_state=EntityState(..., state='off'))

The physical light turned off and the backend returned a verified post-call state.

[devin-ai-integration]

Devin Review found 2 new potential issues.

View 3 additional findings in Devin Review.

[devin-ai-integration]

🚩 httpx is used but not declared as a direct dependency

The _backend.py module imports httpx directly at line 4, and the HomeAssistantBackend.__init__ constructs httpx.AsyncClient instances. However, httpx is not listed in pyproject.toml dependencies — it's only available transitively through pydantic-ai-slim. If pydantic-ai-slim ever makes httpx optional, this module would break at import time. Consider adding a home-automation optional dependency extra (similar to the code-mode extra for pydantic-monty) that includes httpx.

---

Was this helpful? React with 👍 or 👎 to provide feedback.