[automation] Eliminate trigger trampolines with deduplicated forwarder structs (#15174)

esphome/automation.py

@@ -137,6 +137,9 @@ UpdateComponentAction = cg.esphome_ns.class_("UpdateComponentAction", Action)
 SuspendComponentAction = cg.esphome_ns.class_("SuspendComponentAction", Action)
 ResumeComponentAction = cg.esphome_ns.class_("ResumeComponentAction", Action)
 Automation = cg.esphome_ns.class_("Automation")
+TriggerForwarder = cg.esphome_ns.class_("TriggerForwarder")
+TriggerOnTrueForwarder = cg.esphome_ns.class_("TriggerOnTrueForwarder")
+TriggerOnFalseForwarder = cg.esphome_ns.class_("TriggerOnFalseForwarder")
 
 LambdaCondition = cg.esphome_ns.class_("LambdaCondition", Condition)
 StatelessLambdaCondition = cg.esphome_ns.class_("StatelessLambdaCondition", Condition)
@@ -661,3 +664,44 @@ async def build_automation(
     actions = await build_action_list(config[CONF_THEN], templ, args)
     cg.add(obj.add_actions(actions))
     return obj
+
+
+async def build_callback_automation(
+    parent: MockObj,
+    callback_method: str,
+    args: TemplateArgsType,
+    config: ConfigType,
+    forwarder: MockObj | MockObjClass | None = None,
+) -> None:
+    """Build an Automation and register it as a callback on the parent.
+
+    Eliminates the need for a Trigger wrapper object by registering the
+    automation's trigger() directly as a callback on the parent component.
+
+    Uses template forwarder structs so the compiler deduplicates the operator()
+    body across all call sites with the same signature. The forwarder must be
+    pointer-sized (single Automation* field) to fit inline in Callback::ctx_
+    and avoid heap allocation.
+
+    :param parent: The component object (e.g., button, sensor).
+    :param callback_method: Name of the callback method (e.g., "add_on_press_callback").
+    :param args: Automation template args as list of (type, name) tuples.
+    :param config: The automation config dict.
+    :param forwarder: Optional forwarder type to use instead of the default
+        TriggerForwarder<Ts...>. Pass any struct type whose aggregate init takes
+        a single Automation pointer (e.g., TriggerOnTrueForwarder).
+    """
+    arg_types = [arg[0] for arg in args]
+    templ = cg.TemplateArguments(*arg_types)
+    obj = cg.new_Pvariable(config[CONF_AUTOMATION_ID], templ)
+    actions = await build_action_list(config[CONF_THEN], templ, args)
+    cg.add(obj.add_actions(actions))
+    # Use template forwarder structs for deduplication. The compiler generates
+    # one operator() per forwarder type; different automation pointers are just
+    # data in the struct.
+    if forwarder is None:
+        forwarder = TriggerForwarder.template(templ)
+    # RawExpression for aggregate init — both forwarder and obj are codegen
+    # MockObjs (not user input), and there's no Expression type for positional
+    # aggregate initialization (StructInitializer uses named fields).
+    cg.add(getattr(parent, callback_method)(cg.RawExpression(f"{forwarder}{{{obj}}}")))

esphome/components/binary_sensor/__init__.py

@@ -120,10 +120,6 @@ BinarySensorInitiallyOff = binary_sensor_ns.class_(
 BinarySensorPtr = BinarySensor.operator("ptr")
 
 # Triggers
-PressTrigger = binary_sensor_ns.class_("PressTrigger", automation.Trigger.template())
-ReleaseTrigger = binary_sensor_ns.class_(
-    "ReleaseTrigger", automation.Trigger.template()
-)
 ClickTrigger = binary_sensor_ns.class_("ClickTrigger", automation.Trigger.template())
 DoubleClickTrigger = binary_sensor_ns.class_(
     "DoubleClickTrigger", automation.Trigger.template()
@@ -132,13 +128,6 @@ MultiClickTrigger = binary_sensor_ns.class_(
     "MultiClickTrigger", automation.Trigger.template(), cg.Component
 )
 MultiClickTriggerEvent = binary_sensor_ns.struct("MultiClickTriggerEvent")
-StateTrigger = binary_sensor_ns.class_(
-    "StateTrigger", automation.Trigger.template(bool)
-)
-StateChangeTrigger = binary_sensor_ns.class_(
-    "StateChangeTrigger",
-    automation.Trigger.template(cg.optional.template(bool), cg.optional.template(bool)),
-)
 
 BinarySensorPublishAction = binary_sensor_ns.class_(
     "BinarySensorPublishAction", automation.Action
@@ -458,16 +447,8 @@ _BINARY_SENSOR_SCHEMA = (
             ): cv.boolean,
             cv.Optional(CONF_DEVICE_CLASS): validate_device_class,
             cv.Optional(CONF_FILTERS): validate_filters,
-            cv.Optional(CONF_ON_PRESS): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(PressTrigger),
-                }
-            ),
-            cv.Optional(CONF_ON_RELEASE): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(ReleaseTrigger),
-                }
-            ),
+            cv.Optional(CONF_ON_PRESS): automation.validate_automation({}),
+            cv.Optional(CONF_ON_RELEASE): automation.validate_automation({}),
             cv.Optional(CONF_ON_CLICK): cv.All(
                 automation.validate_automation(
                     {
@@ -509,16 +490,8 @@ _BINARY_SENSOR_SCHEMA = (
                     ): cv.positive_time_period_milliseconds,
                 }
             ),
-            cv.Optional(CONF_ON_STATE): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(StateTrigger),
-                }
-            ),
-            cv.Optional(CONF_ON_STATE_CHANGE): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(StateChangeTrigger),
-                }
-            ),
+            cv.Optional(CONF_ON_STATE): automation.validate_automation({}),
+            cv.Optional(CONF_ON_STATE_CHANGE): automation.validate_automation({}),
         }
     )
 )
@@ -556,13 +529,14 @@ def binary_sensor_schema(
 
 @coroutine_with_priority(CoroPriority.AUTOMATION)
 async def _build_binary_sensor_automations(var, config):
-    for conf in config.get(CONF_ON_PRESS, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [], conf)
-
-    for conf in config.get(CONF_ON_RELEASE, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [], conf)
+    for conf_key, forwarder in (
+        (CONF_ON_PRESS, automation.TriggerOnTrueForwarder),
+        (CONF_ON_RELEASE, automation.TriggerOnFalseForwarder),
+    ):
+        for conf in config.get(conf_key, []):
+            await automation.build_callback_automation(
+                var, "add_on_state_callback", [], conf, forwarder=forwarder
+            )
 
     for conf in config.get(CONF_ON_CLICK, []):
         trigger = cg.new_Pvariable(
@@ -593,13 +567,14 @@ async def _build_binary_sensor_automations(var, config):
         await automation.build_automation(trigger, [], conf)
 
     for conf in config.get(CONF_ON_STATE, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [(bool, "x")], conf)
+        await automation.build_callback_automation(
+            var, "add_on_state_callback", [(bool, "x")], conf
+        )
 
     for conf in config.get(CONF_ON_STATE_CHANGE, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(
-            trigger,
+        await automation.build_callback_automation(
+            var,
+            "add_full_state_callback",
             [
                 (cg.optional.template(bool), "x_previous"),
                 (cg.optional.template(bool), "x"),

esphome/components/button/__init__.py

@@ -10,7 +10,6 @@ from esphome.const import (
     CONF_ID,
     CONF_MQTT_ID,
     CONF_ON_PRESS,
-    CONF_TRIGGER_ID,
     CONF_WEB_SERVER,
     DEVICE_CLASS_EMPTY,
     DEVICE_CLASS_IDENTIFY,
@@ -41,10 +40,6 @@ ButtonPtr = Button.operator("ptr")
 
 PressAction = button_ns.class_("PressAction", automation.Action)
 
-ButtonPressTrigger = button_ns.class_(
-    "ButtonPressTrigger", automation.Trigger.template()
-)
-
 validate_device_class = cv.one_of(*DEVICE_CLASSES, lower=True, space="_")
 
 
@@ -55,11 +50,7 @@ _BUTTON_SCHEMA = (
         {
             cv.OnlyWith(CONF_MQTT_ID, "mqtt"): cv.declare_id(mqtt.MQTTButtonComponent),
             cv.Optional(CONF_DEVICE_CLASS): validate_device_class,
-            cv.Optional(CONF_ON_PRESS): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(ButtonPressTrigger),
-                }
-            ),
+            cv.Optional(CONF_ON_PRESS): automation.validate_automation({}),
         }
     )
 )
@@ -91,8 +82,9 @@ def button_schema(
 @setup_entity("button")
 async def setup_button_core_(var, config):
     for conf in config.get(CONF_ON_PRESS, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [], conf)
+        await automation.build_callback_automation(
+            var, "add_on_press_callback", [], conf
+        )
 
     setup_device_class(config)
 

esphome/components/event/__init__.py

@@ -10,7 +10,6 @@ from esphome.const import (
     CONF_ID,
     CONF_MQTT_ID,
     CONF_ON_EVENT,
-    CONF_TRIGGER_ID,
     CONF_WEB_SERVER,
     DEVICE_CLASS_BUTTON,
     DEVICE_CLASS_DOORBELL,
@@ -41,8 +40,6 @@ EventPtr = Event.operator("ptr")
 
 TriggerEventAction = event_ns.class_("TriggerEventAction", automation.Action)
 
-EventTrigger = event_ns.class_("EventTrigger", automation.Trigger.template())
-
 validate_device_class = cv.one_of(*DEVICE_CLASSES, lower=True, space="_")
 
 _EVENT_SCHEMA = (
@@ -53,11 +50,7 @@ _EVENT_SCHEMA = (
             cv.OnlyWith(CONF_MQTT_ID, "mqtt"): cv.declare_id(mqtt.MQTTEventComponent),
             cv.GenerateID(): cv.declare_id(Event),
             cv.Optional(CONF_DEVICE_CLASS): validate_device_class,
-            cv.Optional(CONF_ON_EVENT): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(EventTrigger),
-                }
-            ),
+            cv.Optional(CONF_ON_EVENT): automation.validate_automation({}),
         }
     )
 )
@@ -92,8 +85,9 @@ def event_schema(
 @setup_entity("event")
 async def setup_event_core_(var, config, *, event_types: list[str]):
     for conf in config.get(CONF_ON_EVENT, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [(cg.StringRef, "event_type")], conf)
+        await automation.build_callback_automation(
+            var, "add_on_event_callback", [(cg.StringRef, "event_type")], conf
+        )
 
     cg.add(var.set_event_types(event_types))
 

esphome/components/number/__init__.py

@@ -155,9 +155,6 @@ Number = number_ns.class_("Number", cg.EntityBase)
 NumberPtr = Number.operator("ptr")
 
 # Triggers
-NumberStateTrigger = number_ns.class_(
-    "NumberStateTrigger", automation.Trigger.template(cg.float_)
-)
 ValueRangeTrigger = number_ns.class_(
     "ValueRangeTrigger", automation.Trigger.template(cg.float_), cg.Component
 )
@@ -198,11 +195,7 @@ _NUMBER_SCHEMA = (
     .extend(
         {
             cv.OnlyWith(CONF_MQTT_ID, "mqtt"): cv.declare_id(mqtt.MQTTNumberComponent),
-            cv.Optional(CONF_ON_VALUE): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(NumberStateTrigger),
-                }
-            ),
+            cv.Optional(CONF_ON_VALUE): automation.validate_automation({}),
             cv.Optional(CONF_ON_VALUE_RANGE): automation.validate_automation(
                 {
                     cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(ValueRangeTrigger),
@@ -248,8 +241,9 @@ def number_schema(
 @coroutine_with_priority(CoroPriority.AUTOMATION)
 async def _build_number_automations(var, config):
     for conf in config.get(CONF_ON_VALUE, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [(float, "x")], conf)
+        await automation.build_callback_automation(
+            var, "add_on_state_callback", [(float, "x")], conf
+        )
     for conf in config.get(CONF_ON_VALUE_RANGE, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
         await cg.register_component(trigger, conf)

esphome/components/sensor/__init__.py

@@ -238,12 +238,6 @@ Sensor = sensor_ns.class_("Sensor", cg.EntityBase)
 SensorPtr = Sensor.operator("ptr")
 
 # Triggers
-SensorStateTrigger = sensor_ns.class_(
-    "SensorStateTrigger", automation.Trigger.template(cg.float_)
-)
-SensorRawStateTrigger = sensor_ns.class_(
-    "SensorRawStateTrigger", automation.Trigger.template(cg.float_)
-)
 ValueRangeTrigger = sensor_ns.class_(
     "ValueRangeTrigger", automation.Trigger.template(cg.float_), cg.Component
 )
@@ -316,18 +310,8 @@ _SENSOR_SCHEMA = (
                 cv.Any(None, cv.positive_time_period_milliseconds),
             ),
             cv.Optional(CONF_FILTERS): validate_filters,
-            cv.Optional(CONF_ON_VALUE): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(SensorStateTrigger),
-                }
-            ),
-            cv.Optional(CONF_ON_RAW_VALUE): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(
-                        SensorRawStateTrigger
-                    ),
-                }
-            ),
+            cv.Optional(CONF_ON_VALUE): automation.validate_automation({}),
+            cv.Optional(CONF_ON_RAW_VALUE): automation.validate_automation({}),
             cv.Optional(CONF_ON_VALUE_RANGE): automation.validate_automation(
                 {
                     cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(ValueRangeTrigger),
@@ -897,12 +881,14 @@ async def build_filters(config):
 
 @coroutine_with_priority(CoroPriority.AUTOMATION)
 async def _build_sensor_automations(var, config):
-    for conf in config.get(CONF_ON_VALUE, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [(float, "x")], conf)
-    for conf in config.get(CONF_ON_RAW_VALUE, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [(float, "x")], conf)
+    for conf_key, callback in (
+        (CONF_ON_VALUE, "add_on_state_callback"),
+        (CONF_ON_RAW_VALUE, "add_on_raw_state_callback"),
+    ):
+        for conf in config.get(conf_key, []):
+            await automation.build_callback_automation(
+                var, callback, [(float, "x")], conf
+            )
     for conf in config.get(CONF_ON_VALUE_RANGE, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
         await cg.register_component(trigger, conf)

esphome/components/switch/__init__.py

@@ -15,7 +15,6 @@ from esphome.const import (
     CONF_ON_TURN_ON,
     CONF_RESTORE_MODE,
     CONF_STATE,
-    CONF_TRIGGER_ID,
     CONF_WEB_SERVER,
     DEVICE_CLASS_EMPTY,
     DEVICE_CLASS_OUTLET,
@@ -61,17 +60,6 @@ TurnOnAction = switch_ns.class_("TurnOnAction", automation.Action)
 SwitchPublishAction = switch_ns.class_("SwitchPublishAction", automation.Action)
 
 SwitchCondition = switch_ns.class_("SwitchCondition", Condition)
-SwitchStateTrigger = switch_ns.class_(
-    "SwitchStateTrigger", automation.Trigger.template(bool)
-)
-SwitchTurnOnTrigger = switch_ns.class_(
-    "SwitchTurnOnTrigger", automation.Trigger.template()
-)
-SwitchTurnOffTrigger = switch_ns.class_(
-    "SwitchTurnOffTrigger", automation.Trigger.template()
-)
-
-
 validate_device_class = cv.one_of(*DEVICE_CLASSES, lower=True)
 
 
@@ -86,21 +74,9 @@ _SWITCH_SCHEMA = (
             cv.Optional(CONF_RESTORE_MODE, default="ALWAYS_OFF"): cv.enum(
                 RESTORE_MODES, upper=True, space="_"
             ),
-            cv.Optional(CONF_ON_STATE): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(SwitchStateTrigger),
-                }
-            ),
-            cv.Optional(CONF_ON_TURN_ON): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(SwitchTurnOnTrigger),
-                }
-            ),
-            cv.Optional(CONF_ON_TURN_OFF): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(SwitchTurnOffTrigger),
-                }
-            ),
+            cv.Optional(CONF_ON_STATE): automation.validate_automation({}),
+            cv.Optional(CONF_ON_TURN_ON): automation.validate_automation({}),
+            cv.Optional(CONF_ON_TURN_OFF): automation.validate_automation({}),
             cv.Optional(CONF_DEVICE_CLASS): validate_device_class,
         }
     )
@@ -147,15 +123,15 @@ def switch_schema(
 
 @coroutine_with_priority(CoroPriority.AUTOMATION)
 async def _build_switch_automations(var, config):
-    for conf in config.get(CONF_ON_STATE, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [(bool, "x")], conf)
-    for conf in config.get(CONF_ON_TURN_ON, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [], conf)
-    for conf in config.get(CONF_ON_TURN_OFF, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [], conf)
+    for conf_key, args, forwarder in (
+        (CONF_ON_STATE, [(bool, "x")], None),
+        (CONF_ON_TURN_ON, [], automation.TriggerOnTrueForwarder),
+        (CONF_ON_TURN_OFF, [], automation.TriggerOnFalseForwarder),
+    ):
+        for conf in config.get(conf_key, []):
+            await automation.build_callback_automation(
+                var, "add_on_state_callback", args, conf, forwarder=forwarder
+            )
 
 
 @setup_entity("switch")

esphome/components/text_sensor/__init__.py

@@ -14,7 +14,6 @@ from esphome.const import (
     CONF_ON_VALUE,
     CONF_STATE,
     CONF_TO,
-    CONF_TRIGGER_ID,
     CONF_WEB_SERVER,
     DEVICE_CLASS_DATE,
     DEVICE_CLASS_EMPTY,
@@ -42,12 +41,6 @@ text_sensor_ns = cg.esphome_ns.namespace("text_sensor")
 TextSensor = text_sensor_ns.class_("TextSensor", cg.EntityBase)
 TextSensorPtr = TextSensor.operator("ptr")
 
-TextSensorStateTrigger = text_sensor_ns.class_(
-    "TextSensorStateTrigger", automation.Trigger.template(cg.std_string)
-)
-TextSensorStateRawTrigger = text_sensor_ns.class_(
-    "TextSensorStateRawTrigger", automation.Trigger.template(cg.std_string)
-)
 TextSensorPublishAction = text_sensor_ns.class_(
     "TextSensorPublishAction", automation.Action
 )
@@ -150,20 +143,8 @@ _TEXT_SENSOR_SCHEMA = (
             cv.GenerateID(): cv.declare_id(TextSensor),
             cv.Optional(CONF_DEVICE_CLASS): validate_device_class,
             cv.Optional(CONF_FILTERS): validate_filters,
-            cv.Optional(CONF_ON_VALUE): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(
-                        TextSensorStateTrigger
-                    ),
-                }
-            ),
-            cv.Optional(CONF_ON_RAW_VALUE): automation.validate_automation(
-                {
-                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(
-                        TextSensorStateRawTrigger
-                    ),
-                }
-            ),
+            cv.Optional(CONF_ON_VALUE): automation.validate_automation({}),
+            cv.Optional(CONF_ON_RAW_VALUE): automation.validate_automation({}),
         }
     )
 )
@@ -203,13 +184,14 @@ async def build_filters(config):
 
 @coroutine_with_priority(CoroPriority.AUTOMATION)
 async def _build_text_sensor_automations(var, config):
-    for conf in config.get(CONF_ON_VALUE, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [(cg.std_string, "x")], conf)
-
-    for conf in config.get(CONF_ON_RAW_VALUE, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [(cg.std_string, "x")], conf)
+    for conf_key, callback in (
+        (CONF_ON_VALUE, "add_on_state_callback"),
+        (CONF_ON_RAW_VALUE, "add_on_raw_state_callback"),
+    ):
+        for conf in config.get(conf_key, []):
+            await automation.build_callback_automation(
+                var, callback, [(cg.std_string, "x")], conf
+            )
 
 
 @setup_entity("text_sensor")

esphome/core/automation.h

@@ -470,7 +470,9 @@ template<typename... Ts> class ActionList {
 
 template<typename... Ts> class Automation {
  public:
-  explicit Automation(Trigger<Ts...> *trigger) : trigger_(trigger) { this->trigger_->set_automation_parent(this); }
+  /// Default constructor for use with TriggerForwarder (no Trigger object needed).
+  Automation() = default;
+  explicit Automation(Trigger<Ts...> *trigger) { trigger->set_automation_parent(this); }
 
   void add_action(Action<Ts...> *action) { this->actions_.add_action(action); }
   void add_actions(const std::initializer_list<Action<Ts...> *> &actions) { this->actions_.add_actions(actions); }
@@ -487,8 +489,44 @@ template<typename... Ts> class Automation {
   int num_running() { return this->actions_.num_running(); }
 
  protected:
-  Trigger<Ts...> *trigger_;
   ActionList<Ts...> actions_;
 };
 
+/// Callback forwarder that triggers an Automation directly.
+/// One operator() instantiation per Automation<Ts...> signature, shared across all call sites.
+/// Must stay pointer-sized to fit inline in Callback::ctx_ without heap allocation.
+template<typename... Ts> struct TriggerForwarder {
+  Automation<Ts...> *automation;
+  void operator()(const Ts &...args) const { this->automation->trigger(args...); }
+};
+
+/// Callback forwarder that triggers an Automation<> only when the bool arg is true.
+/// Must stay pointer-sized to fit inline in Callback::ctx_ without heap allocation.
+struct TriggerOnTrueForwarder {
+  Automation<> *automation;
+  void operator()(bool state) const {
+    if (state)
+      this->automation->trigger();
+  }
+};
+
+/// Callback forwarder that triggers an Automation<> only when the bool arg is false.
+/// Must stay pointer-sized to fit inline in Callback::ctx_ without heap allocation.
+struct TriggerOnFalseForwarder {
+  Automation<> *automation;
+  void operator()(bool state) const {
+    if (!state)
+      this->automation->trigger();
+  }
+};
+
+// Ensure forwarders fit in Callback::ctx_ (pointer-sized inline storage).
+// If these fail, the forwarder would heap-allocate in Callback::create().
+static_assert(sizeof(TriggerForwarder<>) <= sizeof(void *));
+static_assert(sizeof(TriggerOnTrueForwarder) <= sizeof(void *));
+static_assert(sizeof(TriggerOnFalseForwarder) <= sizeof(void *));
+static_assert(std::is_trivially_copyable_v<TriggerForwarder<>>);
+static_assert(std::is_trivially_copyable_v<TriggerOnTrueForwarder>);
+static_assert(std::is_trivially_copyable_v<TriggerOnFalseForwarder>);
+
 }  // namespace esphome

tests/unit_tests/test_automation.py

@@ -5,7 +5,13 @@ from unittest.mock import patch
 
 import pytest
 
-from esphome.automation import has_non_synchronous_actions
+from esphome.automation import (
+    TriggerForwarder,
+    TriggerOnFalseForwarder,
+    TriggerOnTrueForwarder,
+    has_non_synchronous_actions,
+)
+from esphome.cpp_generator import MockObj, RawExpression
 from esphome.util import RegistryEntry
 
 
@@ -175,3 +181,76 @@ def test_has_non_synchronous_actions_dict_input(
     """Direct dict input (single action)."""
     assert has_non_synchronous_actions({"delay": "1s"}) is True
     assert has_non_synchronous_actions({"logger.log": "hello"}) is False
+
+
+def _build_forwarder(
+    automation_name: str,
+    args: list[tuple[str, str]],
+    forwarder: MockObj | None = None,
+) -> str:
+    """Build a trigger forwarder expression the same way build_callback_automation does.
+
+    Mirrors the forwarder selection logic in automation.build_callback_automation.
+    """
+    import esphome.codegen as cg
+
+    obj = MockObj(automation_name, "->")
+    if forwarder is None:
+        arg_types = [RawExpression(t) for t, _ in args]
+        templ = (
+            cg.TemplateArguments(*arg_types) if arg_types else cg.TemplateArguments()
+        )
+        forwarder = TriggerForwarder.template(templ)
+    return f"{forwarder}{{{obj}}}"
+
+
+def test_trigger_forwarder_no_args() -> None:
+    """Button on_press: TriggerForwarder<> with no args."""
+    result = _build_forwarder("auto_1", [])
+    assert result == "TriggerForwarder<>{auto_1}"
+
+
+def test_trigger_forwarder_single_float_arg() -> None:
+    """Sensor on_value: TriggerForwarder<float>."""
+    result = _build_forwarder("auto_1", [("float", "x")])
+    assert result == "TriggerForwarder<float>{auto_1}"
+
+
+def test_trigger_forwarder_single_bool_arg() -> None:
+    """Switch on_state: TriggerForwarder<bool>."""
+    result = _build_forwarder("auto_1", [("bool", "x")])
+    assert result == "TriggerForwarder<bool>{auto_1}"
+
+
+def test_trigger_forwarder_on_true() -> None:
+    """Binary_sensor on_press / switch on_turn_on: TriggerOnTrueForwarder."""
+    result = _build_forwarder("auto_1", [], forwarder=TriggerOnTrueForwarder)
+    assert result == "TriggerOnTrueForwarder{auto_1}"
+
+
+def test_trigger_forwarder_on_false() -> None:
+    """Binary_sensor on_release / switch on_turn_off: TriggerOnFalseForwarder."""
+    result = _build_forwarder("auto_1", [], forwarder=TriggerOnFalseForwarder)
+    assert result == "TriggerOnFalseForwarder{auto_1}"
+
+
+def test_trigger_forwarder_multiple_args() -> None:
+    """Binary_sensor on_state_change: TriggerForwarder with two args."""
+    result = _build_forwarder(
+        "auto_1",
+        [("optional<bool>", "x_previous"), ("optional<bool>", "x")],
+    )
+    assert result == "TriggerForwarder<optional<bool>, optional<bool>>{auto_1}"
+
+
+def test_trigger_forwarder_string_arg() -> None:
+    """Text_sensor on_value: TriggerForwarder<std::string>."""
+    result = _build_forwarder("auto_1", [("std::string", "x")])
+    assert result == "TriggerForwarder<std::string>{auto_1}"
+
+
+def test_trigger_forwarder_custom_type() -> None:
+    """Custom forwarder type passed directly."""
+    custom = MockObj("MyForwarder", "")
+    result = _build_forwarder("auto_1", [], forwarder=custom)
+    assert result == "MyForwarder{auto_1}"