[core] Eliminate trigger trampolines for common entity automations

Add build_callback_automation() to register automation callbacks
directly on parent components, bypassing the Trigger wrapper object.

Migrates button, sensor, binary_sensor, switch, and text_sensor
to the new pattern, eliminating 12 thin wrapper trigger classes
from runtime instantiation.

esphome/automation.py

@@ -661,3 +661,48 @@ 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,
+    callback_args: TemplateArgsType | None = None,
+    condition: str | 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.
+
+    :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 callback_args: Lambda parameter types if different from args (e.g., for
+        conditional triggers where the callback receives (bool state) but the
+        automation is Automation<> with no args). Defaults to args.
+    :param condition: Optional C++ condition. Use callback arg names directly
+        (e.g., "state", "!state").
+    """
+    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))
+    # Build trigger call expression: automation->trigger(arg1, arg2, ...)
+    trigger_args = [MockObj(arg[1], "") for arg in args]
+    trigger_expr = obj.trigger(*trigger_args)
+    if condition is not None:
+        body = [f"if ({condition}) {{ ", trigger_expr, "; }"]
+    else:
+        body = [trigger_expr, ";"]
+    # Use callback_args for the lambda parameters if provided (e.g., when the
+    # callback signature differs from the automation args due to filtering).
+    lambda_params = callback_args if callback_args is not None else args
+    # ESPHome codegen allocates all variables as static pointers, so they
+    # are accessible without explicit lambda capture. Using "" avoids
+    # -Wcapture-of-non-automatic-storage-duration warnings.
+    lambda_expr = LambdaExpression(body, lambda_params, capture="")
+    cg.add(getattr(parent, callback_method)(lambda_expr))

esphome/components/binary_sensor/__init__.py

@@ -557,12 +557,24 @@ 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)
+        await automation.build_callback_automation(
+            var,
+            "add_on_state_callback",
+            [],
+            conf,
+            callback_args=[(bool, "state")],
+            condition="state",
+        )
 
     for conf in config.get(CONF_ON_RELEASE, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [], conf)
+        await automation.build_callback_automation(
+            var,
+            "add_on_state_callback",
+            [],
+            conf,
+            callback_args=[(bool, "state")],
+            condition="!state",
+        )
 
     for conf in config.get(CONF_ON_CLICK, []):
         trigger = cg.new_Pvariable(
@@ -593,13 +605,14 @@ 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

@@ -91,8 +91,9 @@ 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/sensor/__init__.py

@@ -898,11 +898,13 @@ 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)
+        await automation.build_callback_automation(
+            var, "add_on_state_callback", [(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)
+        await automation.build_callback_automation(
+            var, "add_on_raw_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/switch/__init__.py

@@ -148,14 +148,27 @@ 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)
+        await automation.build_callback_automation(
+            var, "add_on_state_callback", [(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)
+        await automation.build_callback_automation(
+            var,
+            "add_on_state_callback",
+            [],
+            conf,
+            callback_args=[(bool, "state")],
+            condition="state",
+        )
     for conf in config.get(CONF_ON_TURN_OFF, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [], conf)
+        await automation.build_callback_automation(
+            var,
+            "add_on_state_callback",
+            [],
+            conf,
+            callback_args=[(bool, "state")],
+            condition="!state",
+        )
 
 
 @setup_entity("switch")

esphome/components/text_sensor/__init__.py

@@ -204,12 +204,14 @@ 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)
+        await automation.build_callback_automation(
+            var, "add_on_state_callback", [(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)
+        await automation.build_callback_automation(
+            var, "add_on_raw_state_callback", [(cg.std_string, "x")], conf
+        )
 
 
 @setup_entity("text_sensor")

esphome/core/automation.h

@@ -470,6 +470,7 @@ template<typename... Ts> class ActionList {
 
 template<typename... Ts> class Automation {
  public:
+  Automation() = default;
   explicit Automation(Trigger<Ts...> *trigger) : trigger_(trigger) { this->trigger_->set_automation_parent(this); }
 
   void add_action(Action<Ts...> *action) { this->actions_.add_action(action); }
@@ -487,7 +488,7 @@ template<typename... Ts> class Automation {
   int num_running() { return this->actions_.num_running(); }
 
  protected:
-  Trigger<Ts...> *trigger_;
+  Trigger<Ts...> *trigger_{nullptr};
   ActionList<Ts...> actions_;
 };