[api][climate][water_heater][core] Add temperature unit support to climate and water heater c++ entities (#16477)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

esphome/components/api/api_connection.cpp

@@ -794,6 +794,7 @@ uint16_t APIConnection::try_send_climate_info(EntityBase *entity, APIConnection
   msg.supports_action = traits.has_feature_flags(climate::CLIMATE_SUPPORTS_ACTION);
   // Current feature flags and other supported parameters
   msg.feature_flags = traits.get_feature_flags();
+  msg.temperature_unit = static_cast<enums::TemperatureUnit>(traits.get_temperature_unit());
   msg.supported_modes = &traits.get_supported_modes();
   msg.visual_min_temperature = traits.get_visual_min_temperature();
   msg.visual_max_temperature = traits.get_visual_max_temperature();
@@ -1468,6 +1469,7 @@ uint16_t APIConnection::try_send_water_heater_info(EntityBase *entity, APIConnec
   msg.target_temperature_step = traits.get_target_temperature_step();
   msg.supported_modes = &traits.get_supported_modes();
   msg.supported_features = traits.get_feature_flags();
+  msg.temperature_unit = static_cast<enums::TemperatureUnit>(traits.get_temperature_unit());
   return fill_and_encode_entity_info(wh, msg, conn, remaining_size);
 }
 

esphome/components/climate/__init__.py

@@ -274,7 +274,7 @@ def climate_schema(
 
 @setup_entity("climate")
 async def setup_climate_core_(var, config):
-    visual = config[CONF_VISUAL]
+    visual = config.get(CONF_VISUAL, {})
     if (min_temp := visual.get(CONF_MIN_TEMPERATURE)) is not None:
         cg.add_define("USE_CLIMATE_VISUAL_OVERRIDES")
         cg.add(var.set_visual_min_temperature_override(min_temp))

esphome/components/climate/climate_traits.h

@@ -205,6 +205,9 @@ class ClimateTraits {
   float get_visual_max_humidity() const { return this->visual_max_humidity_; }
   void set_visual_max_humidity(float visual_max_humidity) { this->visual_max_humidity_ = visual_max_humidity; }
 
+  TemperatureUnit get_temperature_unit() const { return this->temperature_unit_; }
+  void set_temperature_unit(TemperatureUnit unit) { this->temperature_unit_ = unit; }
+
  protected:
   void set_mode_support_(climate::ClimateMode mode, bool supported) {
     if (supported) {
@@ -274,6 +277,7 @@ class ClimateTraits {
   climate::ClimateFanModeMask supported_fan_modes_;
   climate::ClimateSwingModeMask supported_swing_modes_;
   climate::ClimatePresetMask supported_presets_;
+  TemperatureUnit temperature_unit_{TemperatureUnit::CELSIUS};
 
   /** Custom mode storage - pointers to vectors owned by the Climate base class.
    *

esphome/components/water_heater/__init__.py

@@ -76,7 +76,7 @@ def water_heater_schema(
 @setup_entity("water_heater")
 async def setup_water_heater_core_(var: cg.Pvariable, config: ConfigType) -> None:
     """Set up the core water heater properties in C++."""
-    visual = config[CONF_VISUAL]
+    visual = config.get(CONF_VISUAL, {})
     if (min_temp := visual.get(CONF_MIN_TEMPERATURE)) is not None:
         cg.add_define("USE_WATER_HEATER_VISUAL_OVERRIDES")
         cg.add(var.set_visual_min_temperature_override(min_temp))

esphome/components/water_heater/water_heater.h

@@ -183,6 +183,9 @@ class WaterHeaterTraits {
   const WaterHeaterModeMask &get_supported_modes() const { return this->supported_modes_; }
   bool supports_mode(WaterHeaterMode mode) const { return this->supported_modes_.count(mode); }
 
+  TemperatureUnit get_temperature_unit() const { return this->temperature_unit_; }
+  void set_temperature_unit(TemperatureUnit unit) { this->temperature_unit_ = unit; }
+
  protected:
   // Ordered to minimize padding: 4-byte members first
   uint32_t feature_flags_{0};
@@ -190,6 +193,7 @@ class WaterHeaterTraits {
   float max_temperature_{0.0f};
   float target_temperature_step_{0.0f};
   WaterHeaterModeMask supported_modes_;
+  TemperatureUnit temperature_unit_{TemperatureUnit::CELSIUS};
 };
 
 class WaterHeater : public EntityBase {

esphome/core/helpers.h

@@ -1625,6 +1625,12 @@ constexpr float celsius_to_fahrenheit(float value) { return value * 1.8f + 32.0f
 /// Convert degrees Fahrenheit to degrees Celsius.
 constexpr float fahrenheit_to_celsius(float value) { return (value - 32.0f) / 1.8f; }
 
+enum class TemperatureUnit : uint8_t {
+  CELSIUS = 0,
+  FAHRENHEIT = 1,
+  KELVIN = 2,
+};
+
 ///@}
 
 /// @name Utilities