Add diagnostics platform to airgradient (#126886)

homeassistant/components/airgradient/diagnostics.py

@@ -0,0 +1,18 @@
+"""Diagnostics support for Airgradient."""
+
+from __future__ import annotations
+
+from dataclasses import asdict
+from typing import Any
+
+from homeassistant.core import HomeAssistant
+
+from . import AirGradientConfigEntry
+
+
+async def async_get_config_entry_diagnostics(
+    hass: HomeAssistant, entry: AirGradientConfigEntry
+) -> dict[str, Any]:
+    """Return diagnostics for a config entry."""
+
+    return asdict(entry.runtime_data.data)