Home Assistant onboarding, MQTT config-entry setup, WebSocket registry access, REST state/service helpers, and readiness waiting;
retained MQTT publishing and discovery observation; and
JSON/JSONL artifact output plus bounded retry helpers.

It deliberately contains no ArduinoHA discovery fixture, DeviceFramework import, entity expectation, or release policy. ArduinoHA owns its migration fixture in tests/ha-test-harness; DeviceFramework owns its hardware fixture and Docker adapter in its own repository. Other projects can reuse this package by providing their own retained MQTT messages and assertions.

The package is copied into a test container as a local build context and is not part of the Arduino firmware library export.