Fix Modbus temperature restoration using the saved unit (#185991)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: abmantis

homeassistant/components/modbus/climate.py

@@ -39,6 +39,7 @@
 from homeassistant.helpers.entity_platform import AddEntitiesCallback
 from homeassistant.helpers.restore_state import RestoreEntity
 from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType
+from homeassistant.util.unit_conversion import TemperatureConverter
 
 from . import get_hub
 from .const import (
@@ -318,8 +319,13 @@ async def async_added_to_hass(self) -> None:
         if state and state.attributes.get(
             ClimateEntityStateAttribute.TARGET_TEMPERATURE
         ):
-            self._attr_native_target_temperature = float(
-                state.attributes[ClimateEntityStateAttribute.TARGET_TEMPERATURE]
+            self._attr_native_target_temperature = TemperatureConverter.convert(
+                float(state.attributes[ClimateEntityStateAttribute.TARGET_TEMPERATURE]),
+                state.attributes.get(
+                    ClimateEntityStateAttribute.TEMPERATURE_UNIT,
+                    self.hass.config.units.temperature_unit,
+                ),
+                self.native_temperature_unit,
             )
 
     @override

tests/components/modbus/test_climate.py

@@ -101,8 +101,10 @@
     CONF_PLATFORM,
     CONF_SCAN_INTERVAL,
     CONF_SLAVE,
+    CONF_TEMPERATURE_UNIT,
     STATE_UNAVAILABLE,
     STATE_UNKNOWN,
+    UnitOfTemperature,
 )
 from homeassistant.core import DOMAIN as HOMEASSISTANT_DOMAIN, HomeAssistant, State
 from homeassistant.setup import async_setup_component
@@ -1656,6 +1658,140 @@ async def test_restore_state_climate(
     assert state.attributes[ATTR_TEMPERATURE] == 37
 
 
+@pytest.mark.parametrize(
+    ("mock_test_state", "do_config"),
+    [
+        pytest.param(
+            (
+                State(
+                    ENTITY_ID,
+                    HVACMode.AUTO,
+                    {
+                        ATTR_TEMPERATURE: 17,
+                        "temperature_unit": UnitOfTemperature.CELSIUS,
+                    },
+                ),
+            ),
+            {
+                CONF_CLIMATES: [
+                    {
+                        CONF_NAME: TEST_ENTITY_NAME,
+                        CONF_TARGET_TEMP: 117,
+                        CONF_ADDRESS: 117,
+                        CONF_TEMPERATURE_UNIT: "C",
+                    }
+                ],
+            },
+            id="celsius_to_celsius",
+        ),
+        pytest.param(
+            (
+                State(
+                    ENTITY_ID,
+                    HVACMode.AUTO,
+                    {
+                        ATTR_TEMPERATURE: 17,
+                        "temperature_unit": UnitOfTemperature.CELSIUS,
+                    },
+                ),
+            ),
+            {
+                CONF_CLIMATES: [
+                    {
+                        CONF_NAME: TEST_ENTITY_NAME,
+                        CONF_TARGET_TEMP: 117,
+                        CONF_ADDRESS: 117,
+                        CONF_TEMPERATURE_UNIT: "F",
+                    }
+                ],
+            },
+            id="celsius_to_fahrenheit",
+        ),
+        pytest.param(
+            (
+                State(
+                    ENTITY_ID,
+                    HVACMode.AUTO,
+                    {
+                        ATTR_TEMPERATURE: 63,
+                        "temperature_unit": UnitOfTemperature.FAHRENHEIT,
+                    },
+                ),
+            ),
+            {
+                CONF_CLIMATES: [
+                    {
+                        CONF_NAME: TEST_ENTITY_NAME,
+                        CONF_TARGET_TEMP: 117,
+                        CONF_ADDRESS: 117,
+                        CONF_TEMPERATURE_UNIT: "C",
+                    }
+                ],
+            },
+            id="fahrenheit_to_celsius",
+        ),
+        pytest.param(
+            (
+                State(
+                    ENTITY_ID,
+                    HVACMode.AUTO,
+                    {
+                        ATTR_TEMPERATURE: 63,
+                        "temperature_unit": UnitOfTemperature.FAHRENHEIT,
+                    },
+                ),
+            ),
+            {
+                CONF_CLIMATES: [
+                    {
+                        CONF_NAME: TEST_ENTITY_NAME,
+                        CONF_TARGET_TEMP: 117,
+                        CONF_ADDRESS: 117,
+                        CONF_TEMPERATURE_UNIT: "F",
+                    }
+                ],
+            },
+            id="fahrenheit_to_fahrenheit",
+        ),
+        pytest.param(
+            (State(ENTITY_ID, HVACMode.AUTO, {ATTR_TEMPERATURE: 17}),),
+            {
+                CONF_CLIMATES: [
+                    {
+                        CONF_NAME: TEST_ENTITY_NAME,
+                        CONF_TARGET_TEMP: 117,
+                        CONF_ADDRESS: 117,
+                        CONF_TEMPERATURE_UNIT: "C",
+                    }
+                ],
+            },
+            id="legacy_to_celsius",
+        ),
+        pytest.param(
+            (State(ENTITY_ID, HVACMode.AUTO, {ATTR_TEMPERATURE: 17}),),
+            {
+                CONF_CLIMATES: [
+                    {
+                        CONF_NAME: TEST_ENTITY_NAME,
+                        CONF_TARGET_TEMP: 117,
+                        CONF_ADDRESS: 117,
+                        CONF_TEMPERATURE_UNIT: "F",
+                    }
+                ],
+            },
+            id="legacy_to_fahrenheit",
+        ),
+    ],
+    indirect=["mock_test_state"],
+)
+@pytest.mark.usefixtures("mock_test_state", "mock_modbus_to_test_errors_config")
+async def test_restore_temperature_unit(hass: HomeAssistant) -> None:
+    """Test restoration uses the saved unit, falling back to the configured unit."""
+    # The fixture does not poll, so the restored target temperature is kept.
+    state = hass.states.get(ENTITY_ID)
+    assert state.attributes[ATTR_TEMPERATURE] == 17
+
+
 @pytest.mark.parametrize(
     "do_config",
     [