diff --git a/esphome/automation.py b/esphome/automation.py
index 2439b1ddc4..d9b8b2ec57 100644
--- a/esphome/automation.py
+++ b/esphome/automation.py
@@ -57,8 +57,23 @@ def maybe_conf(conf, *validators):
     return validate
 
 
-def register_action(name: str, action_type: MockObjClass, schema: cv.Schema):
-    return ACTION_REGISTRY.register(name, action_type, schema)
+def register_action(
+    name: str,
+    action_type: MockObjClass,
+    schema: cv.Schema,
+    *,
+    synchronous: bool = False,
+):
+    """Register an action type.
+
+    Actions default to ``synchronous=False`` (safe default), meaning string
+    arguments use owning std::string to prevent dangling references.
+
+    Set ``synchronous=True`` only for actions that complete synchronously
+    and never store trigger arguments for later execution.  This allows
+    the code generator to use non-owning StringRef for zero-copy access.
+    """
+    return ACTION_REGISTRY.register(name, action_type, schema, synchronous=synchronous)
 
 
 def register_condition(name: str, condition_type: MockObjClass, schema: cv.Schema):
@@ -335,7 +350,9 @@ async def component_is_idle_condition_to_code(
 
 
 @register_action(
-    "delay", DelayAction, cv.templatable(cv.positive_time_period_milliseconds)
+    "delay",
+    DelayAction,
+    cv.templatable(cv.positive_time_period_milliseconds),
 )
 async def delay_action_to_code(
     config: ConfigType,
@@ -366,6 +383,7 @@ async def delay_action_to_code(
         cv.has_at_least_one_key(CONF_THEN, CONF_ELSE),
         cv.has_at_least_one_key(CONF_CONDITION, CONF_ANY, CONF_ALL),
     ),
+    synchronous=True,
 )
 async def if_action_to_code(
     config: ConfigType,
@@ -394,6 +412,7 @@ async def if_action_to_code(
             cv.Required(CONF_THEN): validate_action_list,
         }
     ),
+    synchronous=True,
 )
 async def while_action_to_code(
     config: ConfigType,
@@ -417,6 +436,7 @@ async def while_action_to_code(
             cv.Required(CONF_THEN): validate_action_list,
         }
     ),
+    synchronous=True,
 )
 async def repeat_action_to_code(
     config: ConfigType,
@@ -461,7 +481,12 @@ async def wait_until_action_to_code(
     return var
 
 
-@register_action("lambda", LambdaAction, cv.lambda_)
+# Lambda executes user C++ inline and returns — synchronous by execution model.
+# User code could theoretically store the StringRef for deferred use, but StringRef
+# is a view type and storing views beyond their scope is always unsafe regardless
+# of this optimization.  Marking non-synchronous would disable StringRef for nearly
+# all user services since most use lambda.
+@register_action("lambda", LambdaAction, cv.lambda_, synchronous=True)
 async def lambda_action_to_code(
     config: ConfigType,
     action_id: ID,
@@ -480,6 +505,7 @@ async def lambda_action_to_code(
             cv.Required(CONF_ID): cv.use_id(cg.PollingComponent),
         }
     ),
+    synchronous=True,
 )
 async def component_update_action_to_code(
     config: ConfigType,
@@ -499,6 +525,7 @@ async def component_update_action_to_code(
             cv.Required(CONF_ID): cv.use_id(cg.PollingComponent),
         }
     ),
+    synchronous=True,
 )
 async def component_suspend_action_to_code(
     config: ConfigType,
@@ -521,6 +548,7 @@ async def component_suspend_action_to_code(
             ),
         }
     ),
+    synchronous=True,
 )
 async def component_resume_action_to_code(
     config: ConfigType,
@@ -578,6 +606,27 @@ async def build_condition_list(
     return conditions
 
 
+def has_non_synchronous_actions(actions: ConfigType) -> bool:
+    """Check if a validated action list contains any non-synchronous actions.
+
+    Non-synchronous actions (delay, wait_until, script.wait, etc.) store
+    trigger args for later execution, making non-owning types like StringRef
+    unsafe.  Actions that haven't been audited default to non-synchronous.
+    """
+    if isinstance(actions, list):
+        return any(has_non_synchronous_actions(item) for item in actions)
+    if isinstance(actions, dict):
+        for key in actions:
+            if key in ACTION_REGISTRY and not ACTION_REGISTRY[key].synchronous:
+                return True
+        return any(
+            has_non_synchronous_actions(v)
+            for v in actions.values()
+            if isinstance(v, (list, dict))
+        )
+    return False
+
+
 async def build_automation(
     trigger: MockObj, args: TemplateArgsType, config: ConfigType
 ) -> MockObj:
diff --git a/esphome/codegen.py b/esphome/codegen.py
index c5283f4967..30e3135360 100644
--- a/esphome/codegen.py
+++ b/esphome/codegen.py
@@ -11,6 +11,7 @@
 from esphome.cpp_generator import (  # noqa: F401
     ArrayInitializer,
     Expression,
+    FlashStringLiteral,
     LineComment,
     LogStringLiteral,
     MockObj,
diff --git a/esphome/components/alarm_control_panel/alarm_control_panel_call.cpp b/esphome/components/alarm_control_panel/alarm_control_panel_call.cpp
index ba58ee3904..0c43cd555a 100644
--- a/esphome/components/alarm_control_panel/alarm_control_panel_call.cpp
+++ b/esphome/components/alarm_control_panel/alarm_control_panel_call.cpp
@@ -12,7 +12,14 @@ AlarmControlPanelCall::AlarmControlPanelCall(AlarmControlPanel *parent) : parent
 
 AlarmControlPanelCall &AlarmControlPanelCall::set_code(const char *code) {
   if (code != nullptr) {
-    this->code_ = std::string(code);
+    return this->set_code(code, strlen(code));
+  }
+  return *this;
+}
+
+AlarmControlPanelCall &AlarmControlPanelCall::set_code(const char *code, size_t len) {
+  if (code != nullptr) {
+    this->code_ = std::string(code, len);
   }
   return *this;
 }
diff --git a/esphome/components/alarm_control_panel/alarm_control_panel_call.h b/esphome/components/alarm_control_panel/alarm_control_panel_call.h
index 58764ea166..6e39a0a413 100644
--- a/esphome/components/alarm_control_panel/alarm_control_panel_call.h
+++ b/esphome/components/alarm_control_panel/alarm_control_panel_call.h
@@ -15,7 +15,8 @@ class AlarmControlPanelCall {
   AlarmControlPanelCall(AlarmControlPanel *parent);
 
   AlarmControlPanelCall &set_code(const char *code);
-  AlarmControlPanelCall &set_code(const std::string &code) { return this->set_code(code.c_str()); }
+  AlarmControlPanelCall &set_code(const char *code, size_t len);
+  AlarmControlPanelCall &set_code(const std::string &code) { return this->set_code(code.c_str(), code.size()); }
   AlarmControlPanelCall &arm_away();
   AlarmControlPanelCall &arm_home();
   AlarmControlPanelCall &arm_night();
diff --git a/esphome/components/api/__init__.py b/esphome/components/api/__init__.py
index 3f7cafb485..dd99862cc2 100644
--- a/esphome/components/api/__init__.py
+++ b/esphome/components/api/__init__.py
@@ -76,7 +76,7 @@ SERVICE_ARG_NATIVE_TYPES: dict[str, MockObj] = {
     "bool": cg.bool_,
     "int": cg.int32,
     "float": cg.float_,
-    "string": cg.std_string,
+    "string": cg.StringRef,
     "bool[]": cg.FixedVector.template(cg.bool_).operator("const").operator("ref"),
     "int[]": cg.FixedVector.template(cg.int32).operator("const").operator("ref"),
     "float[]": cg.FixedVector.template(cg.float_).operator("const").operator("ref"),
@@ -380,9 +380,18 @@ async def to_code(config: ConfigType) -> None:
                 if is_optional:
                     func_args.append((cg.bool_, "return_response"))
 
+            # Check if action chain has non-synchronous actions that would make
+            # non-owning StringRef dangle (rx_buf_ reused after delay)
+            has_non_synchronous = automation.has_non_synchronous_actions(
+                conf.get(CONF_THEN, [])
+            )
+
             service_arg_names: list[str] = []
             for name, var_ in conf[CONF_VARIABLES].items():
                 native = SERVICE_ARG_NATIVE_TYPES[var_]
+                # Fall back to std::string for string args if non-synchronous actions exist
+                if has_non_synchronous and native is cg.StringRef:
+                    native = cg.std_string
                 service_template_args.append(native)
                 func_args.append((native, name))
                 service_arg_names.append(name)
@@ -509,11 +518,13 @@ HOMEASSISTANT_ACTION_ACTION_SCHEMA = cv.All(
     "homeassistant.action",
     HomeAssistantServiceCallAction,
     HOMEASSISTANT_ACTION_ACTION_SCHEMA,
+    synchronous=True,
 )
 @automation.register_action(
     "homeassistant.service",
     HomeAssistantServiceCallAction,
     HOMEASSISTANT_ACTION_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def homeassistant_service_to_code(
     config: ConfigType,
@@ -524,24 +535,31 @@ async def homeassistant_service_to_code(
     cg.add_define("USE_API_HOMEASSISTANT_SERVICES")
     serv = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, serv, False)
-    templ = await cg.templatable(config[CONF_ACTION], args, None)
+    templ = await cg.templatable(config[CONF_ACTION], args, cg.std_string)
     cg.add(var.set_service(templ))
 
     # Initialize FixedVectors with exact sizes from config
     cg.add(var.init_data(len(config[CONF_DATA])))
     for key, value in config[CONF_DATA].items():
+        # output_type=None because lambdas can return non-string types (int,
+        # float, char*) that TemplatableStringValue converts via to_string.
+        # Static strings are manually wrapped for PROGMEM on ESP8266.
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data(key, templ))
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
+        cg.add(var.add_data(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_data_template(len(config[CONF_DATA_TEMPLATE])))
     for key, value in config[CONF_DATA_TEMPLATE].items():
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data_template(key, templ))
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
+        cg.add(var.add_data_template(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_variable(key, templ))
+        cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
     if on_error := config.get(CONF_ON_ERROR):
         cg.add_define("USE_API_HOMEASSISTANT_ACTION_RESPONSES")
@@ -604,29 +622,37 @@ HOMEASSISTANT_EVENT_ACTION_SCHEMA = cv.Schema(
     "homeassistant.event",
     HomeAssistantServiceCallAction,
     HOMEASSISTANT_EVENT_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def homeassistant_event_to_code(config, action_id, template_arg, args):
     cg.add_define("USE_API_HOMEASSISTANT_SERVICES")
     serv = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, serv, True)
-    templ = await cg.templatable(config[CONF_EVENT], args, None)
+    templ = await cg.templatable(config[CONF_EVENT], args, cg.std_string)
     cg.add(var.set_service(templ))
 
     # Initialize FixedVectors with exact sizes from config
     cg.add(var.init_data(len(config[CONF_DATA])))
     for key, value in config[CONF_DATA].items():
+        # output_type=None because lambdas can return non-string types (int,
+        # float, char*) that TemplatableStringValue converts via to_string.
+        # Static strings are manually wrapped for PROGMEM on ESP8266.
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data(key, templ))
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
+        cg.add(var.add_data(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_data_template(len(config[CONF_DATA_TEMPLATE])))
     for key, value in config[CONF_DATA_TEMPLATE].items():
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data_template(key, templ))
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
+        cg.add(var.add_data_template(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_variable(key, templ))
+        cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
     return var
 
@@ -644,16 +670,17 @@ HOMEASSISTANT_TAG_SCANNED_ACTION_SCHEMA = cv.maybe_simple_value(
     "homeassistant.tag_scanned",
     HomeAssistantServiceCallAction,
     HOMEASSISTANT_TAG_SCANNED_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def homeassistant_tag_scanned_to_code(config, action_id, template_arg, args):
     cg.add_define("USE_API_HOMEASSISTANT_SERVICES")
     serv = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, serv, True)
-    cg.add(var.set_service("esphome.tag_scanned"))
+    cg.add(var.set_service(cg.FlashStringLiteral("esphome.tag_scanned")))
     # Initialize FixedVector with exact size (1 data field)
     cg.add(var.init_data(1))
     templ = await cg.templatable(config[CONF_TAG], args, cg.std_string)
-    cg.add(var.add_data("tag_id", templ))
+    cg.add(var.add_data(cg.FlashStringLiteral("tag_id"), templ))
     return var
 
 
diff --git a/esphome/components/api/api.proto b/esphome/components/api/api.proto
index d7f32cd8d1..802e3e3ae2 100644
--- a/esphome/components/api/api.proto
+++ b/esphome/components/api/api.proto
@@ -834,6 +834,33 @@ message GetTimeRequest {
   option (source) = SOURCE_SERVER;
 }
 
+enum DSTRuleType {
+  DST_RULE_TYPE_NONE = 0;
+  DST_RULE_TYPE_MONTH_WEEK_DAY = 1;
+  DST_RULE_TYPE_JULIAN_NO_LEAP = 2;
+  DST_RULE_TYPE_DAY_OF_YEAR = 3;
+}
+
+message DSTRule {
+  option (source) = SOURCE_CLIENT;
+
+  sint32 time_seconds = 1;
+  uint32 day = 2;
+  DSTRuleType type = 3;
+  uint32 month = 4;
+  uint32 week = 5;
+  uint32 day_of_week = 6;
+}
+
+message ParsedTimezone {
+  option (source) = SOURCE_CLIENT;
+
+  sint32 std_offset_seconds = 1;
+  sint32 dst_offset_seconds = 2;
+  DSTRule dst_start = 3;
+  DSTRule dst_end = 4;
+}
+
 message GetTimeResponse {
   option (id) = 37;
   option (source) = SOURCE_CLIENT;
@@ -841,6 +868,7 @@ message GetTimeResponse {
 
   fixed32 epoch_seconds = 1;
   string timezone = 2;
+  ParsedTimezone parsed_timezone = 3;
 }
 
 // ==================== USER-DEFINES SERVICES ====================
diff --git a/esphome/components/api/api_connection.cpp b/esphome/components/api/api_connection.cpp
index 8b2efdde51..738dd1ef05 100644
--- a/esphome/components/api/api_connection.cpp
+++ b/esphome/components/api/api_connection.cpp
@@ -889,7 +889,7 @@ uint16_t APIConnection::try_send_text_info(EntityBase *entity, APIConnection *co
 }
 void APIConnection::on_text_command_request(const TextCommandRequest &msg) {
   ENTITY_COMMAND_MAKE_CALL(text::Text, text, text)
-  call.set_value(msg.state);
+  call.set_value(msg.state.c_str(), msg.state.size());
   call.perform();
 }
 #endif
@@ -1123,7 +1123,30 @@ void APIConnection::on_get_time_response(const GetTimeResponse &value) {
     homeassistant::global_homeassistant_time->set_epoch_time(value.epoch_seconds);
 #ifdef USE_TIME_TIMEZONE
     if (!value.timezone.empty()) {
-      homeassistant::global_homeassistant_time->set_timezone(value.timezone.c_str(), value.timezone.size());
+      // Check if the sender provided pre-parsed timezone data.
+      // If std_offset is non-zero or DST rules are present, the parsed data was populated.
+      // For UTC (all zeros), string parsing produces the same result, so the fallback is equivalent.
+      const auto &pt = value.parsed_timezone;
+      if (pt.std_offset_seconds != 0 || pt.dst_start.type != enums::DST_RULE_TYPE_NONE) {
+        time::ParsedTimezone tz{};
+        tz.std_offset_seconds = pt.std_offset_seconds;
+        tz.dst_offset_seconds = pt.dst_offset_seconds;
+        tz.dst_start.time_seconds = pt.dst_start.time_seconds;
+        tz.dst_start.day = static_cast<uint16_t>(pt.dst_start.day);
+        tz.dst_start.type = static_cast<time::DSTRuleType>(pt.dst_start.type);
+        tz.dst_start.month = static_cast<uint8_t>(pt.dst_start.month);
+        tz.dst_start.week = static_cast<uint8_t>(pt.dst_start.week);
+        tz.dst_start.day_of_week = static_cast<uint8_t>(pt.dst_start.day_of_week);
+        tz.dst_end.time_seconds = pt.dst_end.time_seconds;
+        tz.dst_end.day = static_cast<uint16_t>(pt.dst_end.day);
+        tz.dst_end.type = static_cast<time::DSTRuleType>(pt.dst_end.type);
+        tz.dst_end.month = static_cast<uint8_t>(pt.dst_end.month);
+        tz.dst_end.week = static_cast<uint8_t>(pt.dst_end.week);
+        tz.dst_end.day_of_week = static_cast<uint8_t>(pt.dst_end.day_of_week);
+        time::set_global_tz(tz);
+      } else {
+        homeassistant::global_homeassistant_time->set_timezone(value.timezone.c_str(), value.timezone.size());
+      }
     }
 #endif
   }
@@ -1337,7 +1360,7 @@ void APIConnection::on_alarm_control_panel_command_request(const AlarmControlPan
       call.pending();
       break;
   }
-  call.set_code(msg.code);
+  call.set_code(msg.code.c_str(), msg.code.size());
   call.perform();
 }
 #endif
@@ -1711,37 +1734,42 @@ void APIConnection::on_home_assistant_state_response(const HomeAssistantStateRes
     return;
   }
 
+  // Null-terminate state in-place for safe c_str() usage (e.g., parse_number in callbacks).
+  // Safe: decode is complete, byte after string data was already consumed during parse,
+  // and frame helpers reserve RX_BUF_NULL_TERMINATOR extra byte in rx_buf_.
+  // const_cast is safe: msg references mutable rx_buf_ data; the const& handler
+  // signature is a generated protobuf pattern, not a true immutability contract.
+  if (!msg.state.empty()) {
+    const_cast<char *>(msg.state.c_str())[msg.state.size()] = '\0';
+  }
+
   for (auto &it : this->parent_->get_state_subs()) {
-    // Compare entity_id: check length matches and content matches
-    size_t entity_id_len = strlen(it.entity_id);
-    if (entity_id_len != msg.entity_id.size() ||
-        memcmp(it.entity_id, msg.entity_id.c_str(), msg.entity_id.size()) != 0) {
+    if (msg.entity_id != it.entity_id) {
       continue;
     }
 
-    // Compare attribute: either both have matching attribute, or both have none
-    size_t sub_attr_len = it.attribute != nullptr ? strlen(it.attribute) : 0;
-    if (sub_attr_len != msg.attribute.size() ||
-        (sub_attr_len > 0 && memcmp(it.attribute, msg.attribute.c_str(), sub_attr_len) != 0)) {
+    // If subscriber has attribute filter (non-null), message attribute must match it;
+    // if subscriber has no filter (nullptr), message must have no attribute.
+    if (it.attribute != nullptr ? msg.attribute != it.attribute : !msg.attribute.empty()) {
       continue;
     }
 
-    // Create null-terminated state for callback (parse_number needs null-termination)
-    // HA state max length is 255 characters, but attributes can be much longer
-    // Use stack buffer for common case (states), heap fallback for large attributes
-    size_t state_len = msg.state.size();
-    SmallBufferWithHeapFallback<MAX_STATE_LEN + 1> state_buf_alloc(state_len + 1);
-    char *state_buf = reinterpret_cast<char *>(state_buf_alloc.get());
-    if (state_len > 0) {
-      memcpy(state_buf, msg.state.c_str(), state_len);
-    }
-    state_buf[state_len] = '\0';
-    it.callback(StringRef(state_buf, state_len));
+    it.callback(msg.state);
   }
 }
 #endif
 #ifdef USE_API_USER_DEFINED_ACTIONS
 void APIConnection::on_execute_service_request(const ExecuteServiceRequest &msg) {
+  // Null-terminate string args in-place for safe c_str() usage in YAML service triggers.
+  // Safe: full ExecuteServiceRequest decode is complete, all bytes in rx_buf_ consumed,
+  // and frame helpers reserve RX_BUF_NULL_TERMINATOR extra byte for the last field.
+  // const_cast is safe: msg references mutable rx_buf_ data; the const& handler
+  // signature is a generated protobuf pattern, not a true immutability contract.
+  for (auto &arg : const_cast<ExecuteServiceRequest &>(msg).args) {
+    if (!arg.string_.empty()) {
+      const_cast<char *>(arg.string_.c_str())[arg.string_.size()] = '\0';
+    }
+  }
   bool found = false;
 #ifdef USE_API_USER_DEFINED_ACTION_RESPONSES
   // Register the call and get a unique server-generated action_call_id
diff --git a/esphome/components/api/api_frame_helper.h b/esphome/components/api/api_frame_helper.h
index 03f3814bb9..2b4e9ea3cd 100644
--- a/esphome/components/api/api_frame_helper.h
+++ b/esphome/components/api/api_frame_helper.h
@@ -29,6 +29,10 @@ static constexpr uint16_t MAX_MESSAGE_SIZE = 8192;  // 8 KiB for ESP8266
 static constexpr uint16_t MAX_MESSAGE_SIZE = 32768;  // 32 KiB for ESP32 and other platforms
 #endif
 
+// Extra byte reserved in rx_buf_ beyond the message size so protobuf
+// StringRef fields can be null-terminated in-place after decode.
+static constexpr uint16_t RX_BUF_NULL_TERMINATOR = 1;
+
 // Maximum number of messages to batch in a single write operation
 // Must be >= MAX_INITIAL_PER_BATCH in api_connection.h (enforced by static_assert there)
 static constexpr size_t MAX_MESSAGES_PER_BATCH = 34;
diff --git a/esphome/components/api/api_frame_helper_noise.cpp b/esphome/components/api/api_frame_helper_noise.cpp
index 2aad732f7f..3ae35e9be8 100644
--- a/esphome/components/api/api_frame_helper_noise.cpp
+++ b/esphome/components/api/api_frame_helper_noise.cpp
@@ -194,16 +194,21 @@ APIError APINoiseFrameHelper::try_read_frame_() {
   uint16_t msg_size = (((uint16_t) rx_header_buf_[1]) << 8) | rx_header_buf_[2];
 
   // Check against size limits to prevent OOM: MAX_HANDSHAKE_SIZE for handshake, MAX_MESSAGE_SIZE for data
-  uint16_t limit = (state_ == State::DATA) ? MAX_MESSAGE_SIZE : MAX_HANDSHAKE_SIZE;
+  bool is_data = (state_ == State::DATA);
+  uint16_t limit = is_data ? MAX_MESSAGE_SIZE : MAX_HANDSHAKE_SIZE;
   if (msg_size > limit) {
     state_ = State::FAILED;
     HELPER_LOG("Bad packet: message size %u exceeds maximum %u", msg_size, limit);
-    return (state_ == State::DATA) ? APIError::BAD_DATA_PACKET : APIError::BAD_HANDSHAKE_PACKET_LEN;
+    return is_data ? APIError::BAD_DATA_PACKET : APIError::BAD_HANDSHAKE_PACKET_LEN;
   }
 
-  // Reserve space for body
-  if (this->rx_buf_.size() != msg_size) {
-    this->rx_buf_.resize(msg_size);
+  // Reserve space for body (+ null terminator in DATA state so protobuf
+  // StringRef fields can be safely null-terminated in-place after decode.
+  // During handshake, rx_buf_.size() is used in prologue construction, so
+  // the buffer must be exactly msg_size to avoid prologue mismatch.)
+  uint16_t alloc_size = msg_size + (is_data ? RX_BUF_NULL_TERMINATOR : 0);
+  if (this->rx_buf_.size() != alloc_size) {
+    this->rx_buf_.resize(alloc_size);
   }
 
   if (rx_buf_len_ < msg_size) {
@@ -407,7 +412,18 @@ APIError APINoiseFrameHelper::read_packet(ReadPacketBuffer *buffer) {
 
   NoiseBuffer mbuf;
   noise_buffer_init(mbuf);
-  noise_buffer_set_inout(mbuf, this->rx_buf_.data(), this->rx_buf_.size(), this->rx_buf_.size());
+  // read_packet() must only be called in DATA state; the extra
+  // RX_BUF_NULL_TERMINATOR byte is only allocated in DATA state
+  // (see try_read_frame_), so calling this during handshake would
+  // underflow the size calculation below.
+#ifdef ESPHOME_DEBUG_API
+  assert(this->state_ == State::DATA);
+#endif
+  // rx_buf_ has RX_BUF_NULL_TERMINATOR extra byte for null termination
+  // (only added in DATA state — see try_read_frame_), so subtract it
+  // to get the actual encrypted data size for decryption.
+  size_t encrypted_size = this->rx_buf_.size() - RX_BUF_NULL_TERMINATOR;
+  noise_buffer_set_inout(mbuf, this->rx_buf_.data(), encrypted_size, encrypted_size);
   int err = noise_cipherstate_decrypt(this->recv_cipher_, &mbuf);
   APIError decrypt_err =
       handle_noise_error_(err, LOG_STR("noise_cipherstate_decrypt"), APIError::CIPHERSTATE_DECRYPT_FAILED);
@@ -574,7 +590,9 @@ APIError APINoiseFrameHelper::init_handshake_() {
 }
 
 APIError APINoiseFrameHelper::check_handshake_finished_() {
+#ifdef ESPHOME_DEBUG_API
   assert(state_ == State::HANDSHAKE);
+#endif
 
   int action = noise_handshakestate_get_action(handshake_);
   if (action == NOISE_ACTION_READ_MESSAGE || action == NOISE_ACTION_WRITE_MESSAGE)
diff --git a/esphome/components/api/api_frame_helper_plaintext.cpp b/esphome/components/api/api_frame_helper_plaintext.cpp
index 5069dbf68b..e2bb56e0ac 100644
--- a/esphome/components/api/api_frame_helper_plaintext.cpp
+++ b/esphome/components/api/api_frame_helper_plaintext.cpp
@@ -163,9 +163,10 @@ APIError APIPlaintextFrameHelper::try_read_frame_() {
   }
   // header reading done
 
-  // Reserve space for body
-  if (this->rx_buf_.size() != this->rx_header_parsed_len_) {
-    this->rx_buf_.resize(this->rx_header_parsed_len_);
+  // Reserve space for body (+ null terminator so protobuf StringRef fields
+  // can be safely null-terminated in-place after decode)
+  if (this->rx_buf_.size() != this->rx_header_parsed_len_ + RX_BUF_NULL_TERMINATOR) {
+    this->rx_buf_.resize(this->rx_header_parsed_len_ + RX_BUF_NULL_TERMINATOR);
   }
 
   if (rx_buf_len_ < rx_header_parsed_len_) {
diff --git a/esphome/components/api/api_pb2.cpp b/esphome/components/api/api_pb2.cpp
index 5c50a8aa5b..9e74d5ddc7 100644
--- a/esphome/components/api/api_pb2.cpp
+++ b/esphome/components/api/api_pb2.cpp
@@ -954,12 +954,66 @@ bool HomeAssistantStateResponse::decode_length(uint32_t field_id, ProtoLengthDel
   return true;
 }
 #endif
+bool DSTRule::decode_varint(uint32_t field_id, ProtoVarInt value) {
+  switch (field_id) {
+    case 1:
+      this->time_seconds = value.as_sint32();
+      break;
+    case 2:
+      this->day = value.as_uint32();
+      break;
+    case 3:
+      this->type = static_cast<enums::DSTRuleType>(value.as_uint32());
+      break;
+    case 4:
+      this->month = value.as_uint32();
+      break;
+    case 5:
+      this->week = value.as_uint32();
+      break;
+    case 6:
+      this->day_of_week = value.as_uint32();
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+bool ParsedTimezone::decode_varint(uint32_t field_id, ProtoVarInt value) {
+  switch (field_id) {
+    case 1:
+      this->std_offset_seconds = value.as_sint32();
+      break;
+    case 2:
+      this->dst_offset_seconds = value.as_sint32();
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+bool ParsedTimezone::decode_length(uint32_t field_id, ProtoLengthDelimited value) {
+  switch (field_id) {
+    case 3:
+      value.decode_to_message(this->dst_start);
+      break;
+    case 4:
+      value.decode_to_message(this->dst_end);
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
 bool GetTimeResponse::decode_length(uint32_t field_id, ProtoLengthDelimited value) {
   switch (field_id) {
     case 2: {
       this->timezone = StringRef(reinterpret_cast<const char *>(value.data()), value.size());
       break;
     }
+    case 3:
+      value.decode_to_message(this->parsed_timezone);
+      break;
     default:
       return false;
   }
diff --git a/esphome/components/api/api_pb2.h b/esphome/components/api/api_pb2.h
index 22dc3de995..a97f6c0a76 100644
--- a/esphome/components/api/api_pb2.h
+++ b/esphome/components/api/api_pb2.h
@@ -63,6 +63,12 @@ enum LogLevel : uint32_t {
   LOG_LEVEL_VERBOSE = 6,
   LOG_LEVEL_VERY_VERBOSE = 7,
 };
+enum DSTRuleType : uint32_t {
+  DST_RULE_TYPE_NONE = 0,
+  DST_RULE_TYPE_MONTH_WEEK_DAY = 1,
+  DST_RULE_TYPE_JULIAN_NO_LEAP = 2,
+  DST_RULE_TYPE_DAY_OF_YEAR = 3,
+};
 #ifdef USE_API_USER_DEFINED_ACTIONS
 enum ServiceArgType : uint32_t {
   SERVICE_ARG_TYPE_BOOL = 0,
@@ -316,7 +322,6 @@ enum ZWaveProxyRequestType : uint32_t {
 
 class InfoResponseProtoMessage : public ProtoMessage {
  public:
-  ~InfoResponseProtoMessage() override = default;
   StringRef object_id{};
   uint32_t key{0};
   StringRef name{};
@@ -330,28 +335,29 @@ class InfoResponseProtoMessage : public ProtoMessage {
 #endif
 
  protected:
+  ~InfoResponseProtoMessage() = default;
 };
 
 class StateResponseProtoMessage : public ProtoMessage {
  public:
-  ~StateResponseProtoMessage() override = default;
   uint32_t key{0};
 #ifdef USE_DEVICES
   uint32_t device_id{0};
 #endif
 
  protected:
+  ~StateResponseProtoMessage() = default;
 };
 
 class CommandProtoMessage : public ProtoDecodableMessage {
  public:
-  ~CommandProtoMessage() override = default;
   uint32_t key{0};
 #ifdef USE_DEVICES
   uint32_t device_id{0};
 #endif
 
  protected:
+  ~CommandProtoMessage() = default;
 };
 class HelloRequest final : public ProtoDecodableMessage {
  public:
@@ -1116,15 +1122,45 @@ class GetTimeRequest final : public ProtoMessage {
 
  protected:
 };
+class DSTRule final : public ProtoDecodableMessage {
+ public:
+  int32_t time_seconds{0};
+  uint32_t day{0};
+  enums::DSTRuleType type{};
+  uint32_t month{0};
+  uint32_t week{0};
+  uint32_t day_of_week{0};
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *dump_to(DumpBuffer &out) const override;
+#endif
+
+ protected:
+  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+};
+class ParsedTimezone final : public ProtoDecodableMessage {
+ public:
+  int32_t std_offset_seconds{0};
+  int32_t dst_offset_seconds{0};
+  DSTRule dst_start{};
+  DSTRule dst_end{};
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *dump_to(DumpBuffer &out) const override;
+#endif
+
+ protected:
+  bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
+  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+};
 class GetTimeResponse final : public ProtoDecodableMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 37;
-  static constexpr uint8_t ESTIMATED_SIZE = 14;
+  static constexpr uint8_t ESTIMATED_SIZE = 31;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "get_time_response"; }
 #endif
   uint32_t epoch_seconds{0};
   StringRef timezone{};
+  ParsedTimezone parsed_timezone{};
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *dump_to(DumpBuffer &out) const override;
 #endif
diff --git a/esphome/components/api/api_pb2_dump.cpp b/esphome/components/api/api_pb2_dump.cpp
index 52d2486410..4eec42e936 100644
--- a/esphome/components/api/api_pb2_dump.cpp
+++ b/esphome/components/api/api_pb2_dump.cpp
@@ -208,6 +208,20 @@ template<> const char *proto_enum_to_string<enums::LogLevel>(enums::LogLevel val
       return "UNKNOWN";
   }
 }
+template<> const char *proto_enum_to_string<enums::DSTRuleType>(enums::DSTRuleType value) {
+  switch (value) {
+    case enums::DST_RULE_TYPE_NONE:
+      return "DST_RULE_TYPE_NONE";
+    case enums::DST_RULE_TYPE_MONTH_WEEK_DAY:
+      return "DST_RULE_TYPE_MONTH_WEEK_DAY";
+    case enums::DST_RULE_TYPE_JULIAN_NO_LEAP:
+      return "DST_RULE_TYPE_JULIAN_NO_LEAP";
+    case enums::DST_RULE_TYPE_DAY_OF_YEAR:
+      return "DST_RULE_TYPE_DAY_OF_YEAR";
+    default:
+      return "UNKNOWN";
+  }
+}
 #ifdef USE_API_USER_DEFINED_ACTIONS
 template<> const char *proto_enum_to_string<enums::ServiceArgType>(enums::ServiceArgType value) {
   switch (value) {
@@ -1254,10 +1268,35 @@ const char *GetTimeRequest::dump_to(DumpBuffer &out) const {
   out.append("GetTimeRequest {}");
   return out.c_str();
 }
+const char *DSTRule::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "DSTRule");
+  dump_field(out, "time_seconds", this->time_seconds);
+  dump_field(out, "day", this->day);
+  dump_field(out, "type", static_cast<enums::DSTRuleType>(this->type));
+  dump_field(out, "month", this->month);
+  dump_field(out, "week", this->week);
+  dump_field(out, "day_of_week", this->day_of_week);
+  return out.c_str();
+}
+const char *ParsedTimezone::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "ParsedTimezone");
+  dump_field(out, "std_offset_seconds", this->std_offset_seconds);
+  dump_field(out, "dst_offset_seconds", this->dst_offset_seconds);
+  out.append("  dst_start: ");
+  this->dst_start.dump_to(out);
+  out.append("\n");
+  out.append("  dst_end: ");
+  this->dst_end.dump_to(out);
+  out.append("\n");
+  return out.c_str();
+}
 const char *GetTimeResponse::dump_to(DumpBuffer &out) const {
   MessageDumpHelper helper(out, "GetTimeResponse");
   dump_field(out, "epoch_seconds", this->epoch_seconds);
   dump_field(out, "timezone", this->timezone);
+  out.append("  parsed_timezone: ");
+  this->parsed_timezone.dump_to(out);
+  out.append("\n");
   return out.c_str();
 }
 #ifdef USE_API_USER_DEFINED_ACTIONS
diff --git a/esphome/components/api/homeassistant_service.h b/esphome/components/api/homeassistant_service.h
index 340699e1a6..9d14061d07 100644
--- a/esphome/components/api/homeassistant_service.h
+++ b/esphome/components/api/homeassistant_service.h
@@ -130,6 +130,20 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
     this->add_kv_(this->variables_, key, std::forward<V>(value));
   }
 
+#ifdef USE_ESP8266
+  // On ESP8266, ESPHOME_F() returns __FlashStringHelper* (PROGMEM pointer).
+  // Store as const char* — populate_service_map copies from PROGMEM at play() time.
+  template<typename V> void add_data(const __FlashStringHelper *key, V &&value) {
+    this->add_kv_(this->data_, reinterpret_cast<const char *>(key), std::forward<V>(value));
+  }
+  template<typename V> void add_data_template(const __FlashStringHelper *key, V &&value) {
+    this->add_kv_(this->data_template_, reinterpret_cast<const char *>(key), std::forward<V>(value));
+  }
+  template<typename V> void add_variable(const __FlashStringHelper *key, V &&value) {
+    this->add_kv_(this->variables_, reinterpret_cast<const char *>(key), std::forward<V>(value));
+  }
+#endif
+
 #ifdef USE_API_HOMEASSISTANT_ACTION_RESPONSES
   template<typename T> void set_response_template(T response_template) {
     this->response_template_ = response_template;
@@ -221,7 +235,32 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
                                    Ts... x) {
     dest.init(source.size());
 
-    // Count non-static strings to allocate exact storage needed
+#ifdef USE_ESP8266
+    // On ESP8266, all static strings from codegen are FLASH_STRING (PROGMEM),
+    // so is_static_string() is always false — the zero-copy STATIC_STRING fast
+    // path from the non-ESP8266 branch cannot trigger. We copy all keys and
+    // values unconditionally: keys via _P functions (may be in PROGMEM), values
+    // via value() which handles FLASH_STRING internally.
+    value_storage.init(source.size() * 2);
+
+    for (auto &it : source) {
+      auto &kv = dest.emplace_back();
+
+      // Key: copy from possible PROGMEM
+      {
+        size_t key_len = strlen_P(it.key);
+        value_storage.push_back(std::string(key_len, '\0'));
+        memcpy_P(value_storage.back().data(), it.key, key_len);
+        kv.key = StringRef(value_storage.back());
+      }
+
+      // Value: value() handles FLASH_STRING via _P functions internally
+      value_storage.push_back(it.value.value(x...));
+      kv.value = StringRef(value_storage.back());
+    }
+#else
+    // On non-ESP8266, strings are directly readable from flash-mapped memory.
+    // Count non-static strings to allocate exact storage needed.
     size_t lambda_count = 0;
     for (const auto &it : source) {
       if (!it.value.is_static_string()) {
@@ -235,14 +274,15 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
       kv.key = StringRef(it.key);
 
       if (it.value.is_static_string()) {
-        // Static string from YAML - zero allocation
+        // Static string — pointer directly readable, zero allocation
         kv.value = StringRef(it.value.get_static_string());
       } else {
-        // Lambda evaluation - store result, reference it
+        // Lambda — evaluate and store result
         value_storage.push_back(it.value.value(x...));
         kv.value = StringRef(value_storage.back());
       }
     }
+#endif
   }
 
   APIServer *parent_;
diff --git a/esphome/components/api/proto.h b/esphome/components/api/proto.h
index c34f7744e6..750fff0810 100644
--- a/esphome/components/api/proto.h
+++ b/esphome/components/api/proto.h
@@ -452,7 +452,6 @@ class DumpBuffer {
 
 class ProtoMessage {
  public:
-  virtual ~ProtoMessage() = default;
   // Default implementation for messages with no fields
   virtual void encode(ProtoWriteBuffer &buffer) const {}
   // Default implementation for messages with no fields
@@ -463,6 +462,11 @@ class ProtoMessage {
   virtual const char *dump_to(DumpBuffer &out) const = 0;
   virtual const char *message_name() const { return "unknown"; }
 #endif
+
+ protected:
+  // Non-virtual: messages are never deleted polymorphically.
+  // Protected prevents accidental `delete base_ptr` (compile error).
+  ~ProtoMessage() = default;
 };
 
 // Base class for messages that support decoding
@@ -482,6 +486,7 @@ class ProtoDecodableMessage : public ProtoMessage {
   static uint32_t count_repeated_field(const uint8_t *buffer, size_t length, uint32_t target_field_id);
 
  protected:
+  ~ProtoDecodableMessage() = default;
   virtual bool decode_varint(uint32_t field_id, ProtoVarInt value) { return false; }
   virtual bool decode_length(uint32_t field_id, ProtoLengthDelimited value) { return false; }
   virtual bool decode_32bit(uint32_t field_id, Proto32Bit value) { return false; }
diff --git a/esphome/components/api/user_services.cpp b/esphome/components/api/user_services.cpp
index 9c2b4aa79a..28a43c656c 100644
--- a/esphome/components/api/user_services.cpp
+++ b/esphome/components/api/user_services.cpp
@@ -1,5 +1,6 @@
 #include "user_services.h"
 #include "esphome/core/log.h"
+#include "esphome/core/string_ref.h"
 
 namespace esphome::api {
 
@@ -11,6 +12,8 @@ template<> int32_t get_execute_arg_value<int32_t>(const ExecuteServiceArgument &
 }
 template<> float get_execute_arg_value<float>(const ExecuteServiceArgument &arg) { return arg.float_; }
 template<> std::string get_execute_arg_value<std::string>(const ExecuteServiceArgument &arg) { return arg.string_; }
+// Zero-copy StringRef version for YAML-generated services (string_ is null-terminated after decode)
+template<> StringRef get_execute_arg_value<StringRef>(const ExecuteServiceArgument &arg) { return arg.string_; }
 
 // Legacy std::vector versions for external components using custom_api_device.h - optimized with reserve
 template<> std::vector<bool> get_execute_arg_value<std::vector<bool>>(const ExecuteServiceArgument &arg) {
@@ -61,6 +64,8 @@ template<> enums::ServiceArgType to_service_arg_type<bool>() { return enums::SER
 template<> enums::ServiceArgType to_service_arg_type<int32_t>() { return enums::SERVICE_ARG_TYPE_INT; }
 template<> enums::ServiceArgType to_service_arg_type<float>() { return enums::SERVICE_ARG_TYPE_FLOAT; }
 template<> enums::ServiceArgType to_service_arg_type<std::string>() { return enums::SERVICE_ARG_TYPE_STRING; }
+// Zero-copy StringRef version for YAML-generated services
+template<> enums::ServiceArgType to_service_arg_type<StringRef>() { return enums::SERVICE_ARG_TYPE_STRING; }
 
 // Legacy std::vector versions for external components using custom_api_device.h
 template<> enums::ServiceArgType to_service_arg_type<std::vector<bool>>() { return enums::SERVICE_ARG_TYPE_BOOL_ARRAY; }
diff --git a/esphome/components/button/__init__.py b/esphome/components/button/__init__.py
index d2f143b97e..94816a0974 100644
--- a/esphome/components/button/__init__.py
+++ b/esphome/components/button/__init__.py
@@ -123,7 +123,9 @@ BUTTON_PRESS_SCHEMA = maybe_simple_id(
 )
 
 
-@automation.register_action("button.press", PressAction, BUTTON_PRESS_SCHEMA)
+@automation.register_action(
+    "button.press", PressAction, BUTTON_PRESS_SCHEMA, synchronous=True
+)
 async def button_press_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
     return cg.new_Pvariable(action_id, template_arg, paren)
diff --git a/esphome/components/climate/climate.cpp b/esphome/components/climate/climate.cpp
index ba6de4ff61..43d25effa3 100644
--- a/esphome/components/climate/climate.cpp
+++ b/esphome/components/climate/climate.cpp
@@ -173,14 +173,17 @@ ClimateCall &ClimateCall::set_mode(ClimateMode mode) {
   return *this;
 }
 
-ClimateCall &ClimateCall::set_mode(const std::string &mode) {
+ClimateCall &ClimateCall::set_mode(const std::string &mode) { return this->set_mode(mode.c_str(), mode.size()); }
+
+ClimateCall &ClimateCall::set_mode(const char *mode, size_t len) {
+  StringRef mode_ref(mode, len);
   for (const auto &mode_entry : CLIMATE_MODES_BY_STR) {
-    if (str_equals_case_insensitive(mode, mode_entry.str)) {
+    if (str_equals_case_insensitive(mode_ref, mode_entry.str)) {
       this->set_mode(static_cast<ClimateMode>(mode_entry.value));
       return *this;
     }
   }
-  ESP_LOGW(TAG, "'%s' - Unrecognized mode %s", this->parent_->get_name().c_str(), mode.c_str());
+  ESP_LOGW(TAG, "'%s' - Unrecognized mode %.*s", this->parent_->get_name().c_str(), (int) len, mode);
   return *this;
 }
 
@@ -266,13 +269,18 @@ ClimateCall &ClimateCall::set_swing_mode(ClimateSwingMode swing_mode) {
 }
 
 ClimateCall &ClimateCall::set_swing_mode(const std::string &swing_mode) {
+  return this->set_swing_mode(swing_mode.c_str(), swing_mode.size());
+}
+
+ClimateCall &ClimateCall::set_swing_mode(const char *swing_mode, size_t len) {
+  StringRef mode_ref(swing_mode, len);
   for (const auto &mode_entry : CLIMATE_SWING_MODES_BY_STR) {
-    if (str_equals_case_insensitive(swing_mode, mode_entry.str)) {
+    if (str_equals_case_insensitive(mode_ref, mode_entry.str)) {
       this->set_swing_mode(static_cast<ClimateSwingMode>(mode_entry.value));
       return *this;
     }
   }
-  ESP_LOGW(TAG, "'%s' - Unrecognized swing mode %s", this->parent_->get_name().c_str(), swing_mode.c_str());
+  ESP_LOGW(TAG, "'%s' - Unrecognized swing mode %.*s", this->parent_->get_name().c_str(), (int) len, swing_mode);
   return *this;
 }
 
diff --git a/esphome/components/climate/climate.h b/esphome/components/climate/climate.h
index 6fac254502..aa9ca91bc2 100644
--- a/esphome/components/climate/climate.h
+++ b/esphome/components/climate/climate.h
@@ -41,6 +41,8 @@ class ClimateCall {
   ClimateCall &set_mode(optional<ClimateMode> mode);
   /// Set the mode of the climate device based on a string.
   ClimateCall &set_mode(const std::string &mode);
+  /// Set the mode of the climate device based on a C string.
+  ClimateCall &set_mode(const char *mode, size_t len);
   /// Set the target temperature of the climate device.
   ClimateCall &set_target_temperature(float target_temperature);
   /// Set the target temperature of the climate device.
@@ -87,6 +89,8 @@ class ClimateCall {
   ClimateCall &set_swing_mode(optional<ClimateSwingMode> swing_mode);
   /// Set the swing mode of the climate device based on a string.
   ClimateCall &set_swing_mode(const std::string &swing_mode);
+  /// Set the swing mode of the climate device based on a C string.
+  ClimateCall &set_swing_mode(const char *swing_mode, size_t len);
   /// Set the preset of the climate device.
   ClimateCall &set_preset(ClimatePreset preset);
   /// Set the preset of the climate device.
diff --git a/esphome/components/cover/__init__.py b/esphome/components/cover/__init__.py
index 648fe7decf..17095f41f6 100644
--- a/esphome/components/cover/__init__.py
+++ b/esphome/components/cover/__init__.py
@@ -248,25 +248,33 @@ COVER_ACTION_SCHEMA = maybe_simple_id(
 )
 
 
-@automation.register_action("cover.open", OpenAction, COVER_ACTION_SCHEMA)
+@automation.register_action(
+    "cover.open", OpenAction, COVER_ACTION_SCHEMA, synchronous=True
+)
 async def cover_open_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
     return cg.new_Pvariable(action_id, template_arg, paren)
 
 
-@automation.register_action("cover.close", CloseAction, COVER_ACTION_SCHEMA)
+@automation.register_action(
+    "cover.close", CloseAction, COVER_ACTION_SCHEMA, synchronous=True
+)
 async def cover_close_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
     return cg.new_Pvariable(action_id, template_arg, paren)
 
 
-@automation.register_action("cover.stop", StopAction, COVER_ACTION_SCHEMA)
+@automation.register_action(
+    "cover.stop", StopAction, COVER_ACTION_SCHEMA, synchronous=True
+)
 async def cover_stop_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
     return cg.new_Pvariable(action_id, template_arg, paren)
 
 
-@automation.register_action("cover.toggle", ToggleAction, COVER_ACTION_SCHEMA)
+@automation.register_action(
+    "cover.toggle", ToggleAction, COVER_ACTION_SCHEMA, synchronous=True
+)
 async def cover_toggle_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
     return cg.new_Pvariable(action_id, template_arg, paren)
@@ -283,7 +291,9 @@ COVER_CONTROL_ACTION_SCHEMA = cv.Schema(
 )
 
 
-@automation.register_action("cover.control", ControlAction, COVER_CONTROL_ACTION_SCHEMA)
+@automation.register_action(
+    "cover.control", ControlAction, COVER_CONTROL_ACTION_SCHEMA, synchronous=True
+)
 async def cover_control_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, paren)
diff --git a/esphome/components/esp32/__init__.py b/esphome/components/esp32/__init__.py
index dd9e394fd2..a14d3af69e 100644
--- a/esphome/components/esp32/__init__.py
+++ b/esphome/components/esp32/__init__.py
@@ -1438,6 +1438,7 @@ async def to_code(config):
 
     cg.set_cpp_standard("gnu++20")
     cg.add_build_flag("-DUSE_ESP32")
+    cg.add_define("USE_NATIVE_64BIT_TIME")
     cg.add_build_flag("-Wl,-z,noexecstack")
     cg.add_define("ESPHOME_BOARD", config[CONF_BOARD])
     variant = config[CONF_VARIANT]
diff --git a/esphome/components/esp32/core.cpp b/esphome/components/esp32/core.cpp
index b9ae871abf..59b791da40 100644
--- a/esphome/components/esp32/core.cpp
+++ b/esphome/components/esp32/core.cpp
@@ -48,6 +48,7 @@ void arch_init() {
 void HOT arch_feed_wdt() { esp_task_wdt_reset(); }
 
 uint8_t progmem_read_byte(const uint8_t *addr) { return *addr; }
+uint16_t progmem_read_uint16(const uint16_t *addr) { return *addr; }
 uint32_t arch_get_cpu_cycle_count() { return esp_cpu_get_cycle_count(); }
 uint32_t arch_get_cpu_freq_hz() {
   uint32_t freq = 0;
diff --git a/esphome/components/esp32/preferences.cpp b/esphome/components/esp32/preferences.cpp
index 8d6fdc86f6..a3ef10b21f 100644
--- a/esphome/components/esp32/preferences.cpp
+++ b/esphome/components/esp32/preferences.cpp
@@ -19,16 +19,7 @@ static constexpr size_t KEY_BUFFER_SIZE = 12;
 
 struct NVSData {
   uint32_t key;
-  std::unique_ptr<uint8_t[]> data;
-  size_t len;
-
-  void set_data(const uint8_t *src, size_t size) {
-    if (!this->data || this->len != size) {
-      this->data = std::make_unique<uint8_t[]>(size);
-      this->len = size;
-    }
-    memcpy(this->data.get(), src, size);
-  }
+  SmallInlineBuffer<8> data;  // Most prefs fit in 8 bytes (covers fan, cover, select, etc.)
 };
 
 static std::vector<NVSData> s_pending_save;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
@@ -41,14 +32,14 @@ class ESP32PreferenceBackend : public ESPPreferenceBackend {
     // try find in pending saves and update that
     for (auto &obj : s_pending_save) {
       if (obj.key == this->key) {
-        obj.set_data(data, len);
+        obj.data.set(data, len);
         return true;
       }
     }
     NVSData save{};
     save.key = this->key;
-    save.set_data(data, len);
-    s_pending_save.emplace_back(std::move(save));
+    save.data.set(data, len);
+    s_pending_save.push_back(std::move(save));
     ESP_LOGVV(TAG, "s_pending_save: key: %" PRIu32 ", len: %zu", this->key, len);
     return true;
   }
@@ -56,11 +47,11 @@ class ESP32PreferenceBackend : public ESPPreferenceBackend {
     // try find in pending saves and load from that
     for (auto &obj : s_pending_save) {
       if (obj.key == this->key) {
-        if (obj.len != len) {
+        if (obj.data.size() != len) {
           // size mismatch
           return false;
         }
-        memcpy(data, obj.data.get(), len);
+        memcpy(data, obj.data.data(), len);
         return true;
       }
     }
@@ -133,10 +124,10 @@ class ESP32Preferences : public ESPPreferences {
       snprintf(key_str, sizeof(key_str), "%" PRIu32, save.key);
       ESP_LOGVV(TAG, "Checking if NVS data %s has changed", key_str);
       if (this->is_changed_(this->nvs_handle, save, key_str)) {
-        esp_err_t err = nvs_set_blob(this->nvs_handle, key_str, save.data.get(), save.len);
-        ESP_LOGV(TAG, "sync: key: %s, len: %zu", key_str, save.len);
+        esp_err_t err = nvs_set_blob(this->nvs_handle, key_str, save.data.data(), save.data.size());
+        ESP_LOGV(TAG, "sync: key: %s, len: %zu", key_str, save.data.size());
         if (err != 0) {
-          ESP_LOGV(TAG, "nvs_set_blob('%s', len=%zu) failed: %s", key_str, save.len, esp_err_to_name(err));
+          ESP_LOGV(TAG, "nvs_set_blob('%s', len=%zu) failed: %s", key_str, save.data.size(), esp_err_to_name(err));
           failed++;
           last_err = err;
           last_key = save.key;
@@ -144,7 +135,7 @@ class ESP32Preferences : public ESPPreferences {
         }
         written++;
       } else {
-        ESP_LOGV(TAG, "NVS data not changed skipping %" PRIu32 "  len=%zu", save.key, save.len);
+        ESP_LOGV(TAG, "NVS data not changed skipping %" PRIu32 "  len=%zu", save.key, save.data.size());
         cached++;
       }
     }
@@ -176,7 +167,7 @@ class ESP32Preferences : public ESPPreferences {
       return true;
     }
     // Check size first before allocating memory
-    if (actual_len != to_save.len) {
+    if (actual_len != to_save.data.size()) {
       return true;
     }
     // Most preferences are small, use stack buffer with heap fallback for large ones
@@ -186,7 +177,7 @@ class ESP32Preferences : public ESPPreferences {
       ESP_LOGV(TAG, "nvs_get_blob('%s') failed: %s", key_str, esp_err_to_name(err));
       return true;
     }
-    return memcmp(to_save.data.get(), stored_data.get(), to_save.len) != 0;
+    return memcmp(to_save.data.data(), stored_data.get(), to_save.data.size()) != 0;
   }
 
   bool reset() override {
diff --git a/esphome/components/esp8266/core.cpp b/esphome/components/esp8266/core.cpp
index 497e99b61f..b665124d66 100644
--- a/esphome/components/esp8266/core.cpp
+++ b/esphome/components/esp8266/core.cpp
@@ -3,7 +3,7 @@
 #include "core.h"
 #include "esphome/core/defines.h"
 #include "esphome/core/hal.h"
-#include "esphome/core/application.h"
+#include "esphome/core/time_64.h"
 #include "esphome/core/helpers.h"
 #include "preferences.h"
 #include <Arduino.h>
@@ -17,7 +17,7 @@ namespace esphome {
 
 void HOT yield() { ::yield(); }
 uint32_t IRAM_ATTR HOT millis() { return ::millis(); }
-uint64_t millis_64() { return App.scheduler.millis_64_impl_(::millis()); }
+uint64_t millis_64() { return Millis64Impl::compute(::millis()); }
 void HOT delay(uint32_t ms) { ::delay(ms); }
 uint32_t IRAM_ATTR HOT micros() { return ::micros(); }
 void IRAM_ATTR HOT delayMicroseconds(uint32_t us) { delay_microseconds_safe(us); }
@@ -34,6 +34,9 @@ void HOT arch_feed_wdt() { system_soft_wdt_feed(); }
 uint8_t progmem_read_byte(const uint8_t *addr) {
   return pgm_read_byte(addr);  // NOLINT
 }
+uint16_t progmem_read_uint16(const uint16_t *addr) {
+  return pgm_read_word(addr);  // NOLINT
+}
 uint32_t IRAM_ATTR HOT arch_get_cpu_cycle_count() { return esp_get_cycle_count(); }
 uint32_t arch_get_cpu_freq_hz() { return F_CPU; }
 
diff --git a/esphome/components/fan/__init__.py b/esphome/components/fan/__init__.py
index 6010aa8ed4..e839df6aee 100644
--- a/esphome/components/fan/__init__.py
+++ b/esphome/components/fan/__init__.py
@@ -311,13 +311,17 @@ FAN_ACTION_SCHEMA = maybe_simple_id(
 )
 
 
-@automation.register_action("fan.toggle", ToggleAction, FAN_ACTION_SCHEMA)
+@automation.register_action(
+    "fan.toggle", ToggleAction, FAN_ACTION_SCHEMA, synchronous=True
+)
 async def fan_toggle_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
     return cg.new_Pvariable(action_id, template_arg, paren)
 
 
-@automation.register_action("fan.turn_off", TurnOffAction, FAN_ACTION_SCHEMA)
+@automation.register_action(
+    "fan.turn_off", TurnOffAction, FAN_ACTION_SCHEMA, synchronous=True
+)
 async def fan_turn_off_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
     return cg.new_Pvariable(action_id, template_arg, paren)
@@ -336,6 +340,7 @@ async def fan_turn_off_to_code(config, action_id, template_arg, args):
             ),
         }
     ),
+    synchronous=True,
 )
 async def fan_turn_on_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
diff --git a/esphome/components/globals/__init__.py b/esphome/components/globals/__init__.py
index fc400c5dd1..fe11a93a4b 100644
--- a/esphome/components/globals/__init__.py
+++ b/esphome/components/globals/__init__.py
@@ -102,6 +102,7 @@ async def to_code(config):
             cv.Required(CONF_VALUE): cv.templatable(cv.string_strict),
         }
     ),
+    synchronous=True,
 )
 async def globals_set_to_code(config, action_id, template_arg, args):
     full_id, paren = await cg.get_variable_with_full_id(config[CONF_ID])
diff --git a/esphome/components/host/__init__.py b/esphome/components/host/__init__.py
index ba05e497c8..8adbfb02ec 100644
--- a/esphome/components/host/__init__.py
+++ b/esphome/components/host/__init__.py
@@ -41,6 +41,7 @@ CONFIG_SCHEMA = cv.All(
 
 async def to_code(config):
     cg.add_build_flag("-DUSE_HOST")
+    cg.add_define("USE_NATIVE_64BIT_TIME")
     cg.add_define("USE_ESPHOME_HOST_MAC_ADDRESS", config[CONF_MAC_ADDRESS].parts)
     cg.add_build_flag("-std=gnu++20")
     cg.add_define("ESPHOME_BOARD", "host")
diff --git a/esphome/components/host/core.cpp b/esphome/components/host/core.cpp
index 9af85bec58..cb2b2e19d7 100644
--- a/esphome/components/host/core.cpp
+++ b/esphome/components/host/core.cpp
@@ -59,6 +59,7 @@ void HOT arch_feed_wdt() {
 }
 
 uint8_t progmem_read_byte(const uint8_t *addr) { return *addr; }
+uint16_t progmem_read_uint16(const uint16_t *addr) { return *addr; }
 uint32_t arch_get_cpu_cycle_count() {
   struct timespec spec;
   clock_gettime(CLOCK_MONOTONIC, &spec);
diff --git a/esphome/components/improv_serial/__init__.py b/esphome/components/improv_serial/__init__.py
index 9a2ac2f40f..4266f5b78b 100644
--- a/esphome/components/improv_serial/__init__.py
+++ b/esphome/components/improv_serial/__init__.py
@@ -43,3 +43,4 @@ async def to_code(config):
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await improv_base.setup_improv_core(var, config, "improv_serial")
+    cg.add_define("USE_IMPROV_SERIAL")
diff --git a/esphome/components/libretiny/core.cpp b/esphome/components/libretiny/core.cpp
index 6cbc81938d..74b33a30a0 100644
--- a/esphome/components/libretiny/core.cpp
+++ b/esphome/components/libretiny/core.cpp
@@ -3,7 +3,7 @@
 #include "core.h"
 #include "esphome/core/defines.h"
 #include "esphome/core/hal.h"
-#include "esphome/core/application.h"
+#include "esphome/core/time_64.h"
 #include "esphome/core/helpers.h"
 #include "preferences.h"
 
@@ -14,7 +14,7 @@ namespace esphome {
 
 void HOT yield() { ::yield(); }
 uint32_t IRAM_ATTR HOT millis() { return ::millis(); }
-uint64_t millis_64() { return App.scheduler.millis_64_impl_(::millis()); }
+uint64_t millis_64() { return Millis64Impl::compute(::millis()); }
 uint32_t IRAM_ATTR HOT micros() { return ::micros(); }
 void HOT delay(uint32_t ms) { ::delay(ms); }
 void IRAM_ATTR HOT delayMicroseconds(uint32_t us) { ::delayMicroseconds(us); }
@@ -36,6 +36,7 @@ void HOT arch_feed_wdt() { lt_wdt_feed(); }
 uint32_t arch_get_cpu_cycle_count() { return lt_cpu_get_cycle_count(); }
 uint32_t arch_get_cpu_freq_hz() { return lt_cpu_get_freq(); }
 uint8_t progmem_read_byte(const uint8_t *addr) { return *addr; }
+uint16_t progmem_read_uint16(const uint16_t *addr) { return *addr; }
 
 }  // namespace esphome
 
diff --git a/esphome/components/libretiny/preferences.cpp b/esphome/components/libretiny/preferences.cpp
index 740c1a233a..1c101136e1 100644
--- a/esphome/components/libretiny/preferences.cpp
+++ b/esphome/components/libretiny/preferences.cpp
@@ -17,16 +17,7 @@ static constexpr size_t KEY_BUFFER_SIZE = 12;
 
 struct NVSData {
   uint32_t key;
-  std::unique_ptr<uint8_t[]> data;
-  size_t len;
-
-  void set_data(const uint8_t *src, size_t size) {
-    if (!this->data || this->len != size) {
-      this->data = std::make_unique<uint8_t[]>(size);
-      this->len = size;
-    }
-    memcpy(this->data.get(), src, size);
-  }
+  SmallInlineBuffer<8> data;  // Most prefs fit in 8 bytes (covers fan, cover, select, etc.)
 };
 
 static std::vector<NVSData> s_pending_save;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
@@ -41,14 +32,14 @@ class LibreTinyPreferenceBackend : public ESPPreferenceBackend {
     // try find in pending saves and update that
     for (auto &obj : s_pending_save) {
       if (obj.key == this->key) {
-        obj.set_data(data, len);
+        obj.data.set(data, len);
         return true;
       }
     }
     NVSData save{};
     save.key = this->key;
-    save.set_data(data, len);
-    s_pending_save.emplace_back(std::move(save));
+    save.data.set(data, len);
+    s_pending_save.push_back(std::move(save));
     ESP_LOGVV(TAG, "s_pending_save: key: %" PRIu32 ", len: %zu", this->key, len);
     return true;
   }
@@ -57,11 +48,11 @@ class LibreTinyPreferenceBackend : public ESPPreferenceBackend {
     // try find in pending saves and load from that
     for (auto &obj : s_pending_save) {
       if (obj.key == this->key) {
-        if (obj.len != len) {
+        if (obj.data.size() != len) {
           // size mismatch
           return false;
         }
-        memcpy(data, obj.data.get(), len);
+        memcpy(data, obj.data.data(), len);
         return true;
       }
     }
@@ -122,11 +113,11 @@ class LibreTinyPreferences : public ESPPreferences {
       snprintf(key_str, sizeof(key_str), "%" PRIu32, save.key);
       ESP_LOGVV(TAG, "Checking if FDB data %s has changed", key_str);
       if (this->is_changed_(&this->db, save, key_str)) {
-        ESP_LOGV(TAG, "sync: key: %s, len: %zu", key_str, save.len);
-        fdb_blob_make(&this->blob, save.data.get(), save.len);
+        ESP_LOGV(TAG, "sync: key: %s, len: %zu", key_str, save.data.size());
+        fdb_blob_make(&this->blob, save.data.data(), save.data.size());
         fdb_err_t err = fdb_kv_set_blob(&this->db, key_str, &this->blob);
         if (err != FDB_NO_ERR) {
-          ESP_LOGV(TAG, "fdb_kv_set_blob('%s', len=%zu) failed: %d", key_str, save.len, err);
+          ESP_LOGV(TAG, "fdb_kv_set_blob('%s', len=%zu) failed: %d", key_str, save.data.size(), err);
           failed++;
           last_err = err;
           last_key = save.key;
@@ -134,7 +125,7 @@ class LibreTinyPreferences : public ESPPreferences {
         }
         written++;
       } else {
-        ESP_LOGD(TAG, "FDB data not changed; skipping %" PRIu32 "  len=%zu", save.key, save.len);
+        ESP_LOGD(TAG, "FDB data not changed; skipping %" PRIu32 "  len=%zu", save.key, save.data.size());
         cached++;
       }
     }
@@ -159,7 +150,7 @@ class LibreTinyPreferences : public ESPPreferences {
     }
 
     // Check size first - if different, data has changed
-    if (kv.value_len != to_save.len) {
+    if (kv.value_len != to_save.data.size()) {
       return true;
     }
 
@@ -173,7 +164,7 @@ class LibreTinyPreferences : public ESPPreferences {
     }
 
     // Compare the actual data
-    return memcmp(to_save.data.get(), stored_data.get(), kv.value_len) != 0;
+    return memcmp(to_save.data.data(), stored_data.get(), kv.value_len) != 0;
   }
 
   bool reset() override {
diff --git a/esphome/components/light/__init__.py b/esphome/components/light/__init__.py
index f1089ad64f..40382bbda7 100644
--- a/esphome/components/light/__init__.py
+++ b/esphome/components/light/__init__.py
@@ -1,3 +1,4 @@
+from dataclasses import dataclass, field
 import enum
 
 import esphome.automation as auto
@@ -37,7 +38,7 @@ from esphome.const import (
     CONF_WEB_SERVER,
     CONF_WHITE,
 )
-from esphome.core import CORE, CoroPriority, coroutine_with_priority
+from esphome.core import CORE, ID, CoroPriority, HexInt, coroutine_with_priority
 from esphome.core.entity_helpers import entity_duplicate_validator, setup_entity
 from esphome.cpp_generator import MockObjClass
 
@@ -66,6 +67,40 @@ from .types import (  # noqa
 CODEOWNERS = ["@esphome/core"]
 IS_PLATFORM_COMPONENT = True
 
+DOMAIN = "light"
+
+
+@dataclass
+class LightData:
+    gamma_tables: dict = field(default_factory=dict)  # gamma_value -> fwd_arr
+
+
+def _get_data() -> LightData:
+    if DOMAIN not in CORE.data:
+        CORE.data[DOMAIN] = LightData()
+    return CORE.data[DOMAIN]
+
+
+def _get_or_create_gamma_table(gamma_correct):
+    data = _get_data()
+    if gamma_correct in data.gamma_tables:
+        return data.gamma_tables[gamma_correct]
+
+    if gamma_correct > 0:
+        forward = [
+            HexInt(min(65535, int(round((i / 255.0) ** gamma_correct * 65535))))
+            for i in range(256)
+        ]
+    else:
+        forward = [HexInt(int(round(i / 255.0 * 65535))) for i in range(256)]
+
+    gamma_str = f"{gamma_correct}".replace(".", "_")
+    fwd_id = ID(f"gamma_{gamma_str}_fwd", is_declaration=True, type=cg.uint16)
+    fwd_arr = cg.progmem_array(fwd_id, forward)
+    data.gamma_tables[gamma_correct] = fwd_arr
+    return fwd_arr
+
+
 LightRestoreMode = light_ns.enum("LightRestoreMode")
 RESTORE_MODES = {
     "RESTORE_DEFAULT_OFF": LightRestoreMode.LIGHT_RESTORE_DEFAULT_OFF,
@@ -239,6 +274,9 @@ async def setup_light_core_(light_var, output_var, config):
         cg.add(light_var.set_flash_transition_length(flash_transition_length))
     if (gamma_correct := config.get(CONF_GAMMA_CORRECT)) is not None:
         cg.add(light_var.set_gamma_correct(gamma_correct))
+        fwd_arr = _get_or_create_gamma_table(gamma_correct)
+        cg.add(light_var.set_gamma_table(fwd_arr))
+        cg.add_define("USE_LIGHT_GAMMA_LUT")
     effects = await cg.build_registry_list(
         EFFECTS_REGISTRY, config.get(CONF_EFFECTS, [])
     )
diff --git a/esphome/components/light/addressable_light.h b/esphome/components/light/addressable_light.h
index fcaf07f578..17cdb7d6f6 100644
--- a/esphome/components/light/addressable_light.h
+++ b/esphome/components/light/addressable_light.h
@@ -66,7 +66,9 @@ class AddressableLight : public LightOutput, public Component {
         Color(to_uint8_scale(red), to_uint8_scale(green), to_uint8_scale(blue), to_uint8_scale(white)));
   }
   void setup_state(LightState *state) override {
-    this->correction_.calculate_gamma_table(state->get_gamma_correct());
+#ifdef USE_LIGHT_GAMMA_LUT
+    this->correction_.set_gamma_table(state->get_gamma_table());
+#endif
     this->state_parent_ = state;
   }
   void update_state(LightState *state) override;
diff --git a/esphome/components/light/addressable_light_wrapper.h b/esphome/components/light/addressable_light_wrapper.h
index cd83482248..cc6aa57905 100644
--- a/esphome/components/light/addressable_light_wrapper.h
+++ b/esphome/components/light/addressable_light_wrapper.h
@@ -74,11 +74,10 @@ class AddressableLightWrapper : public light::AddressableLight {
       return;
     }
 
-    float gamma = this->light_state_->get_gamma_correct();
-    float r = gamma_uncorrect(this->wrapper_state_[0] / 255.0f, gamma);
-    float g = gamma_uncorrect(this->wrapper_state_[1] / 255.0f, gamma);
-    float b = gamma_uncorrect(this->wrapper_state_[2] / 255.0f, gamma);
-    float w = gamma_uncorrect(this->wrapper_state_[3] / 255.0f, gamma);
+    float r = this->light_state_->gamma_uncorrect_lut(this->wrapper_state_[0] / 255.0f);
+    float g = this->light_state_->gamma_uncorrect_lut(this->wrapper_state_[1] / 255.0f);
+    float b = this->light_state_->gamma_uncorrect_lut(this->wrapper_state_[2] / 255.0f);
+    float w = this->light_state_->gamma_uncorrect_lut(this->wrapper_state_[3] / 255.0f);
 
     auto call = this->light_state_->make_call();
 
diff --git a/esphome/components/light/automation.h b/esphome/components/light/automation.h
index c90d71c5df..2854bc62d9 100644
--- a/esphome/components/light/automation.h
+++ b/esphome/components/light/automation.h
@@ -41,7 +41,7 @@ template<typename... Ts> class LightControlAction : public Action<Ts...> {
   TEMPLATABLE_VALUE(float, color_temperature)
   TEMPLATABLE_VALUE(float, cold_white)
   TEMPLATABLE_VALUE(float, warm_white)
-  TEMPLATABLE_VALUE(std::string, effect)
+  TEMPLATABLE_VALUE(uint32_t, effect)
 
   void play(const Ts &...x) override {
     auto call = this->parent_->make_call();
diff --git a/esphome/components/light/automation.py b/esphome/components/light/automation.py
index e5aa8fa0e9..08fd26a937 100644
--- a/esphome/components/light/automation.py
+++ b/esphome/components/light/automation.py
@@ -10,12 +10,14 @@ from esphome.const import (
     CONF_COLOR_MODE,
     CONF_COLOR_TEMPERATURE,
     CONF_EFFECT,
+    CONF_EFFECTS,
     CONF_FLASH_LENGTH,
     CONF_GREEN,
     CONF_ID,
     CONF_LIMIT_MODE,
     CONF_MAX_BRIGHTNESS,
     CONF_MIN_BRIGHTNESS,
+    CONF_NAME,
     CONF_RANGE_FROM,
     CONF_RANGE_TO,
     CONF_RED,
@@ -24,6 +26,9 @@ from esphome.const import (
     CONF_WARM_WHITE,
     CONF_WHITE,
 )
+from esphome.core import CORE, Lambda
+from esphome.cpp_generator import LambdaExpression
+from esphome.types import ConfigType
 
 from .types import (
     COLOR_MODES,
@@ -51,6 +56,7 @@ from .types import (
             ),
         }
     ),
+    synchronous=True,
 )
 async def light_toggle_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -110,14 +116,34 @@ LIGHT_TURN_ON_ACTION_SCHEMA = automation.maybe_simple_id(
 )
 
 
+def _resolve_effect_index(config: ConfigType) -> int:
+    """Resolve a static effect name to its 1-based index at codegen time.
+
+    Effect index 0 means "None" (no effect). Effects are 1-indexed matching
+    the C++ convention in LightState.
+    """
+    original_name = config[CONF_EFFECT]
+    effect_name = original_name.lower()
+    if effect_name == "none":
+        return 0
+    light_id = config[CONF_ID]
+    light_path = CORE.config.get_path_for_id(light_id)[:-1]
+    light_config = CORE.config.get_config_for_path(light_path)
+    for i, effect_conf in enumerate(light_config.get(CONF_EFFECTS, [])):
+        key = next(iter(effect_conf))
+        if effect_conf[key][CONF_NAME].lower() == effect_name:
+            return i + 1
+    raise ValueError(f"Effect '{original_name}' not found in light '{light_id}'")
+
+
 @automation.register_action(
-    "light.turn_off", LightControlAction, LIGHT_TURN_OFF_ACTION_SCHEMA
+    "light.turn_off", LightControlAction, LIGHT_TURN_OFF_ACTION_SCHEMA, synchronous=True
 )
 @automation.register_action(
-    "light.turn_on", LightControlAction, LIGHT_TURN_ON_ACTION_SCHEMA
+    "light.turn_on", LightControlAction, LIGHT_TURN_ON_ACTION_SCHEMA, synchronous=True
 )
 @automation.register_action(
-    "light.control", LightControlAction, LIGHT_CONTROL_ACTION_SCHEMA
+    "light.control", LightControlAction, LIGHT_CONTROL_ACTION_SCHEMA, synchronous=True
 )
 async def light_control_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -164,8 +190,29 @@ async def light_control_to_code(config, action_id, template_arg, args):
         template_ = await cg.templatable(config[CONF_WARM_WHITE], args, float)
         cg.add(var.set_warm_white(template_))
     if CONF_EFFECT in config:
-        template_ = await cg.templatable(config[CONF_EFFECT], args, cg.std_string)
-        cg.add(var.set_effect(template_))
+        if isinstance(config[CONF_EFFECT], Lambda):
+            # Lambda returns a string — wrap in a C++ lambda that resolves
+            # the effect name to its uint32_t index at runtime
+            inner_lambda = await cg.process_lambda(
+                config[CONF_EFFECT], args, return_type=cg.std_string
+            )
+            fwd_args = ", ".join(n for _, n in args)
+            # capture="" is correct: paren is a global variable name
+            # string-interpolated into the body at codegen time, not a
+            # C++ runtime capture.
+            wrapper = LambdaExpression(
+                f"auto __effect_s = ({inner_lambda})({fwd_args});\n"
+                f"return {paren}->get_effect_index("
+                f"__effect_s.c_str(), __effect_s.size());",
+                args,
+                capture="",
+                return_type=cg.uint32,
+            )
+            cg.add(var.set_effect(wrapper))
+        else:
+            # Static string — resolve effect name to index at codegen time
+            effect_index = _resolve_effect_index(config)
+            cg.add(var.set_effect(effect_index))
     return var
 
 
@@ -193,7 +240,10 @@ LIGHT_DIM_RELATIVE_ACTION_SCHEMA = cv.Schema(
 
 
 @automation.register_action(
-    "light.dim_relative", DimRelativeAction, LIGHT_DIM_RELATIVE_ACTION_SCHEMA
+    "light.dim_relative",
+    DimRelativeAction,
+    LIGHT_DIM_RELATIVE_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def light_dim_relative_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
diff --git a/esphome/components/light/esp_color_correction.cpp b/esphome/components/light/esp_color_correction.cpp
index 1b511a94b2..9d731a2bd5 100644
--- a/esphome/components/light/esp_color_correction.cpp
+++ b/esphome/components/light/esp_color_correction.cpp
@@ -1,25 +1,25 @@
 #include "esp_color_correction.h"
-#include "light_color_values.h"
-#include "esphome/core/log.h"
 
 namespace esphome::light {
 
-void ESPColorCorrection::calculate_gamma_table(float gamma) {
-  for (uint16_t i = 0; i < 256; i++) {
-    // corrected = val ^ gamma
-    auto corrected = to_uint8_scale(gamma_correct(i / 255.0f, gamma));
-    this->gamma_table_[i] = corrected;
-  }
-  if (gamma == 0.0f) {
-    for (uint16_t i = 0; i < 256; i++)
-      this->gamma_reverse_table_[i] = i;
-    return;
-  }
-  for (uint16_t i = 0; i < 256; i++) {
-    // val = corrected ^ (1/gamma)
-    auto uncorrected = to_uint8_scale(powf(i / 255.0f, 1.0f / gamma));
-    this->gamma_reverse_table_[i] = uncorrected;
-  }
+uint8_t ESPColorCorrection::gamma_correct_(uint8_t value) const {
+  if (this->gamma_table_ == nullptr)
+    return value;
+  return static_cast<uint8_t>((progmem_read_uint16(&this->gamma_table_[value]) + 128) / 257);
+}
+
+uint8_t ESPColorCorrection::gamma_uncorrect_(uint8_t value) const {
+  if (this->gamma_table_ == nullptr)
+    return value;
+  if (value == 0)
+    return 0;
+  uint16_t target = value * 257;  // Scale 0-255 to 0-65535
+  uint8_t lo = gamma_table_reverse_search(this->gamma_table_, target);
+  if (lo >= 255)
+    return 255;
+  uint16_t a = progmem_read_uint16(&this->gamma_table_[lo]);
+  uint16_t b = progmem_read_uint16(&this->gamma_table_[lo + 1]);
+  return (target - a <= b - target) ? lo : lo + 1;
 }
 
 }  // namespace esphome::light
diff --git a/esphome/components/light/esp_color_correction.h b/esphome/components/light/esp_color_correction.h
index d275e045b7..48ecc46364 100644
--- a/esphome/components/light/esp_color_correction.h
+++ b/esphome/components/light/esp_color_correction.h
@@ -1,15 +1,30 @@
 #pragma once
 
 #include "esphome/core/color.h"
+#include "esphome/core/hal.h"
 
 namespace esphome::light {
 
+/// Binary search a monotonically increasing uint16[256] PROGMEM table.
+/// Returns the largest index where table[index] <= target.
+inline uint8_t gamma_table_reverse_search(const uint16_t *table, uint16_t target) {
+  uint8_t lo = 0, hi = 255;
+  while (lo < hi) {
+    uint8_t mid = (lo + hi + 1) / 2;
+    if (progmem_read_uint16(&table[mid]) <= target) {
+      lo = mid;
+    } else {
+      hi = mid - 1;
+    }
+  }
+  return lo;
+}
+
 class ESPColorCorrection {
  public:
-  ESPColorCorrection() : max_brightness_(255, 255, 255, 255) {}
   void set_max_brightness(const Color &max_brightness) { this->max_brightness_ = max_brightness; }
   void set_local_brightness(uint8_t local_brightness) { this->local_brightness_ = local_brightness; }
-  void calculate_gamma_table(float gamma);
+  void set_gamma_table(const uint16_t *table) { this->gamma_table_ = table; }
   inline Color color_correct(Color color) const ESPHOME_ALWAYS_INLINE {
     // corrected = (uncorrected * max_brightness * local_brightness) ^ gamma
     return Color(this->color_correct_red(color.red), this->color_correct_green(color.green),
@@ -17,19 +32,19 @@ class ESPColorCorrection {
   }
   inline uint8_t color_correct_red(uint8_t red) const ESPHOME_ALWAYS_INLINE {
     uint8_t res = esp_scale8_twice(red, this->max_brightness_.red, this->local_brightness_);
-    return this->gamma_table_[res];
+    return this->gamma_correct_(res);
   }
   inline uint8_t color_correct_green(uint8_t green) const ESPHOME_ALWAYS_INLINE {
     uint8_t res = esp_scale8_twice(green, this->max_brightness_.green, this->local_brightness_);
-    return this->gamma_table_[res];
+    return this->gamma_correct_(res);
   }
   inline uint8_t color_correct_blue(uint8_t blue) const ESPHOME_ALWAYS_INLINE {
     uint8_t res = esp_scale8_twice(blue, this->max_brightness_.blue, this->local_brightness_);
-    return this->gamma_table_[res];
+    return this->gamma_correct_(res);
   }
   inline uint8_t color_correct_white(uint8_t white) const ESPHOME_ALWAYS_INLINE {
     uint8_t res = esp_scale8_twice(white, this->max_brightness_.white, this->local_brightness_);
-    return this->gamma_table_[res];
+    return this->gamma_correct_(res);
   }
   inline Color color_uncorrect(Color color) const ESPHOME_ALWAYS_INLINE {
     // uncorrected = corrected^(1/gamma) / (max_brightness * local_brightness)
@@ -39,36 +54,40 @@ class ESPColorCorrection {
   inline uint8_t color_uncorrect_red(uint8_t red) const ESPHOME_ALWAYS_INLINE {
     if (this->max_brightness_.red == 0 || this->local_brightness_ == 0)
       return 0;
-    uint16_t uncorrected = this->gamma_reverse_table_[red] * 255UL;
+    uint16_t uncorrected = this->gamma_uncorrect_(red) * 255UL;
     uint16_t res = ((uncorrected / this->max_brightness_.red) * 255UL) / this->local_brightness_;
     return (uint8_t) std::min(res, uint16_t(255));
   }
   inline uint8_t color_uncorrect_green(uint8_t green) const ESPHOME_ALWAYS_INLINE {
     if (this->max_brightness_.green == 0 || this->local_brightness_ == 0)
       return 0;
-    uint16_t uncorrected = this->gamma_reverse_table_[green] * 255UL;
+    uint16_t uncorrected = this->gamma_uncorrect_(green) * 255UL;
     uint16_t res = ((uncorrected / this->max_brightness_.green) * 255UL) / this->local_brightness_;
     return (uint8_t) std::min(res, uint16_t(255));
   }
   inline uint8_t color_uncorrect_blue(uint8_t blue) const ESPHOME_ALWAYS_INLINE {
     if (this->max_brightness_.blue == 0 || this->local_brightness_ == 0)
       return 0;
-    uint16_t uncorrected = this->gamma_reverse_table_[blue] * 255UL;
+    uint16_t uncorrected = this->gamma_uncorrect_(blue) * 255UL;
     uint16_t res = ((uncorrected / this->max_brightness_.blue) * 255UL) / this->local_brightness_;
     return (uint8_t) std::min(res, uint16_t(255));
   }
   inline uint8_t color_uncorrect_white(uint8_t white) const ESPHOME_ALWAYS_INLINE {
     if (this->max_brightness_.white == 0 || this->local_brightness_ == 0)
       return 0;
-    uint16_t uncorrected = this->gamma_reverse_table_[white] * 255UL;
+    uint16_t uncorrected = this->gamma_uncorrect_(white) * 255UL;
     uint16_t res = ((uncorrected / this->max_brightness_.white) * 255UL) / this->local_brightness_;
     return (uint8_t) std::min(res, uint16_t(255));
   }
 
  protected:
-  uint8_t gamma_table_[256];
-  uint8_t gamma_reverse_table_[256];
-  Color max_brightness_;
+  /// Forward gamma: read uint16 PROGMEM table, convert to uint8
+  uint8_t gamma_correct_(uint8_t value) const;
+  /// Reverse gamma: binary search the forward PROGMEM table
+  uint8_t gamma_uncorrect_(uint8_t value) const;
+
+  const uint16_t *gamma_table_{nullptr};
+  Color max_brightness_{255, 255, 255, 255};
   uint8_t local_brightness_{255};
 };
 
diff --git a/esphome/components/light/light_call.cpp b/esphome/components/light/light_call.cpp
index 0291b2c3c6..14cd0e92f6 100644
--- a/esphome/components/light/light_call.cpp
+++ b/esphome/components/light/light_call.cpp
@@ -389,9 +389,8 @@ void LightCall::transform_parameters_() {
       const float ww_fraction = (color_temp - min_mireds) / range;
       const float cw_fraction = 1.0f - ww_fraction;
       const float max_cw_ww = std::max(ww_fraction, cw_fraction);
-      const float gamma = this->parent_->get_gamma_correct();
-      this->cold_white_ = gamma_uncorrect(cw_fraction / max_cw_ww, gamma);
-      this->warm_white_ = gamma_uncorrect(ww_fraction / max_cw_ww, gamma);
+      this->cold_white_ = this->parent_->gamma_uncorrect_lut(cw_fraction / max_cw_ww);
+      this->warm_white_ = this->parent_->gamma_uncorrect_lut(ww_fraction / max_cw_ww);
       this->set_flag_(FLAG_HAS_COLD_WHITE);
       this->set_flag_(FLAG_HAS_WARM_WHITE);
     }
diff --git a/esphome/components/light/light_color_values.h b/esphome/components/light/light_color_values.h
index dc23263312..3a9ca8c8c2 100644
--- a/esphome/components/light/light_color_values.h
+++ b/esphome/components/light/light_color_values.h
@@ -111,60 +111,54 @@ class LightColorValues {
     }
   }
 
-  // Note that method signature of as_* methods is kept as-is for compatibility reasons, so not all parameters
-  // are always used or necessary. Methods will be deprecated later.
-
   /// Convert these light color values to a binary representation and write them to binary.
   void as_binary(bool *binary) const { *binary = this->state_ == 1.0f; }
 
   /// Convert these light color values to a brightness-only representation and write them to brightness.
-  void as_brightness(float *brightness, float gamma = 0) const {
-    *brightness = gamma_correct(this->state_ * this->brightness_, gamma);
-  }
+  void as_brightness(float *brightness) const { *brightness = this->state_ * this->brightness_; }
 
   /// Convert these light color values to an RGB representation and write them to red, green, blue.
-  void as_rgb(float *red, float *green, float *blue, float gamma = 0, bool color_interlock = false) const {
+  void as_rgb(float *red, float *green, float *blue) const {
     if (this->color_mode_ & ColorCapability::RGB) {
       float brightness = this->state_ * this->brightness_ * this->color_brightness_;
-      *red = gamma_correct(brightness * this->red_, gamma);
-      *green = gamma_correct(brightness * this->green_, gamma);
-      *blue = gamma_correct(brightness * this->blue_, gamma);
+      *red = brightness * this->red_;
+      *green = brightness * this->green_;
+      *blue = brightness * this->blue_;
     } else {
       *red = *green = *blue = 0;
     }
   }
 
   /// Convert these light color values to an RGBW representation and write them to red, green, blue, white.
-  void as_rgbw(float *red, float *green, float *blue, float *white, float gamma = 0,
-               bool color_interlock = false) const {
-    this->as_rgb(red, green, blue, gamma);
+  void as_rgbw(float *red, float *green, float *blue, float *white) const {
+    this->as_rgb(red, green, blue);
     if (this->color_mode_ & ColorCapability::WHITE) {
-      *white = gamma_correct(this->state_ * this->brightness_ * this->white_, gamma);
+      *white = this->state_ * this->brightness_ * this->white_;
     } else {
       *white = 0;
     }
   }
 
   /// Convert these light color values to an RGBWW representation with the given parameters.
-  void as_rgbww(float *red, float *green, float *blue, float *cold_white, float *warm_white, float gamma = 0,
+  void as_rgbww(float *red, float *green, float *blue, float *cold_white, float *warm_white,
                 bool constant_brightness = false) const {
-    this->as_rgb(red, green, blue, gamma);
-    this->as_cwww(cold_white, warm_white, gamma, constant_brightness);
+    this->as_rgb(red, green, blue);
+    this->as_cwww(cold_white, warm_white, constant_brightness);
   }
 
   /// Convert these light color values to an RGB+CT+BR representation with the given parameters.
   void as_rgbct(float color_temperature_cw, float color_temperature_ww, float *red, float *green, float *blue,
-                float *color_temperature, float *white_brightness, float gamma = 0) const {
-    this->as_rgb(red, green, blue, gamma);
-    this->as_ct(color_temperature_cw, color_temperature_ww, color_temperature, white_brightness, gamma);
+                float *color_temperature, float *white_brightness) const {
+    this->as_rgb(red, green, blue);
+    this->as_ct(color_temperature_cw, color_temperature_ww, color_temperature, white_brightness);
   }
 
   /// Convert these light color values to an CWWW representation with the given parameters.
-  void as_cwww(float *cold_white, float *warm_white, float gamma = 0, bool constant_brightness = false) const {
+  void as_cwww(float *cold_white, float *warm_white, bool constant_brightness = false) const {
     if (this->color_mode_ & ColorCapability::COLD_WARM_WHITE) {
-      const float cw_level = gamma_correct(this->cold_white_, gamma);
-      const float ww_level = gamma_correct(this->warm_white_, gamma);
-      const float white_level = gamma_correct(this->state_ * this->brightness_, gamma);
+      const float cw_level = this->cold_white_;
+      const float ww_level = this->warm_white_;
+      const float white_level = this->state_ * this->brightness_;
       if (!constant_brightness) {
         *cold_white = white_level * cw_level;
         *warm_white = white_level * ww_level;
@@ -184,13 +178,13 @@ class LightColorValues {
   }
 
   /// Convert these light color values to a CT+BR representation with the given parameters.
-  void as_ct(float color_temperature_cw, float color_temperature_ww, float *color_temperature, float *white_brightness,
-             float gamma = 0) const {
+  void as_ct(float color_temperature_cw, float color_temperature_ww, float *color_temperature,
+             float *white_brightness) const {
     const float white_level = this->color_mode_ & ColorCapability::RGB ? this->white_ : 1;
     if (this->color_mode_ & ColorCapability::COLOR_TEMPERATURE) {
       *color_temperature =
           (this->color_temperature_ - color_temperature_cw) / (color_temperature_ww - color_temperature_cw);
-      *white_brightness = gamma_correct(this->state_ * this->brightness_ * white_level, gamma);
+      *white_brightness = this->state_ * this->brightness_ * white_level;
     } else {  // Probably won't get here but put this here anyway.
       *white_brightness = 0;
     }
diff --git a/esphome/components/light/light_state.cpp b/esphome/components/light/light_state.cpp
index ed86bf58da..161092532a 100644
--- a/esphome/components/light/light_state.cpp
+++ b/esphome/components/light/light_state.cpp
@@ -1,4 +1,5 @@
 #include "light_state.h"
+#include "esp_color_correction.h"
 #include "esphome/core/defines.h"
 #include "esphome/core/controller_registry.h"
 #include "esphome/core/log.h"
@@ -204,33 +205,90 @@ void LightState::add_effects(const std::initializer_list<LightEffect *> &effects
 
 void LightState::current_values_as_binary(bool *binary) { this->current_values.as_binary(binary); }
 void LightState::current_values_as_brightness(float *brightness) {
-  this->current_values.as_brightness(brightness, this->gamma_correct_);
+  this->current_values.as_brightness(brightness);
+  *brightness = this->gamma_correct_lut(*brightness);
 }
-void LightState::current_values_as_rgb(float *red, float *green, float *blue, bool color_interlock) {
-  this->current_values.as_rgb(red, green, blue, this->gamma_correct_, false);
+void LightState::current_values_as_rgb(float *red, float *green, float *blue) {
+  this->current_values.as_rgb(red, green, blue);
+  *red = this->gamma_correct_lut(*red);
+  *green = this->gamma_correct_lut(*green);
+  *blue = this->gamma_correct_lut(*blue);
 }
-void LightState::current_values_as_rgbw(float *red, float *green, float *blue, float *white, bool color_interlock) {
-  this->current_values.as_rgbw(red, green, blue, white, this->gamma_correct_, false);
+void LightState::current_values_as_rgbw(float *red, float *green, float *blue, float *white) {
+  this->current_values.as_rgbw(red, green, blue, white);
+  *red = this->gamma_correct_lut(*red);
+  *green = this->gamma_correct_lut(*green);
+  *blue = this->gamma_correct_lut(*blue);
+  *white = this->gamma_correct_lut(*white);
 }
 void LightState::current_values_as_rgbww(float *red, float *green, float *blue, float *cold_white, float *warm_white,
                                          bool constant_brightness) {
-  this->current_values.as_rgbww(red, green, blue, cold_white, warm_white, this->gamma_correct_, constant_brightness);
+  this->current_values.as_rgbww(red, green, blue, cold_white, warm_white, constant_brightness);
+  *red = this->gamma_correct_lut(*red);
+  *green = this->gamma_correct_lut(*green);
+  *blue = this->gamma_correct_lut(*blue);
+  *cold_white = this->gamma_correct_lut(*cold_white);
+  *warm_white = this->gamma_correct_lut(*warm_white);
 }
 void LightState::current_values_as_rgbct(float *red, float *green, float *blue, float *color_temperature,
                                          float *white_brightness) {
   auto traits = this->get_traits();
   this->current_values.as_rgbct(traits.get_min_mireds(), traits.get_max_mireds(), red, green, blue, color_temperature,
-                                white_brightness, this->gamma_correct_);
+                                white_brightness);
+  *red = this->gamma_correct_lut(*red);
+  *green = this->gamma_correct_lut(*green);
+  *blue = this->gamma_correct_lut(*blue);
+  *white_brightness = this->gamma_correct_lut(*white_brightness);
 }
 void LightState::current_values_as_cwww(float *cold_white, float *warm_white, bool constant_brightness) {
-  this->current_values.as_cwww(cold_white, warm_white, this->gamma_correct_, constant_brightness);
+  this->current_values.as_cwww(cold_white, warm_white, constant_brightness);
+  *cold_white = this->gamma_correct_lut(*cold_white);
+  *warm_white = this->gamma_correct_lut(*warm_white);
 }
 void LightState::current_values_as_ct(float *color_temperature, float *white_brightness) {
   auto traits = this->get_traits();
-  this->current_values.as_ct(traits.get_min_mireds(), traits.get_max_mireds(), color_temperature, white_brightness,
-                             this->gamma_correct_);
+  this->current_values.as_ct(traits.get_min_mireds(), traits.get_max_mireds(), color_temperature, white_brightness);
+  *white_brightness = this->gamma_correct_lut(*white_brightness);
 }
 
+#ifdef USE_LIGHT_GAMMA_LUT
+float LightState::gamma_correct_lut(float value) const {
+  if (value <= 0.0f)
+    return 0.0f;
+  if (value >= 1.0f)
+    return 1.0f;
+  if (this->gamma_table_ == nullptr)
+    return value;
+  float scaled = value * 255.0f;
+  auto idx = static_cast<uint8_t>(scaled);
+  if (idx >= 255)
+    return progmem_read_uint16(&this->gamma_table_[255]) / 65535.0f;
+  float frac = scaled - idx;
+  float a = progmem_read_uint16(&this->gamma_table_[idx]);
+  float b = progmem_read_uint16(&this->gamma_table_[idx + 1]);
+  return (a + frac * (b - a)) / 65535.0f;
+}
+float LightState::gamma_uncorrect_lut(float value) const {
+  if (value <= 0.0f)
+    return 0.0f;
+  if (value >= 1.0f)
+    return 1.0f;
+  if (this->gamma_table_ == nullptr)
+    return value;
+  uint16_t target = static_cast<uint16_t>(value * 65535.0f);
+  uint8_t lo = gamma_table_reverse_search(this->gamma_table_, target);
+  if (lo >= 255)
+    return 1.0f;
+  // Interpolate between lo and lo+1
+  uint16_t a = progmem_read_uint16(&this->gamma_table_[lo]);
+  uint16_t b = progmem_read_uint16(&this->gamma_table_[lo + 1]);
+  if (b == a)
+    return lo / 255.0f;
+  float frac = static_cast<float>(target - a) / static_cast<float>(b - a);
+  return (lo + frac) / 255.0f;
+}
+#endif  // USE_LIGHT_GAMMA_LUT
+
 bool LightState::is_transformer_active() { return this->is_transformer_active_; }
 
 void LightState::start_effect_(uint32_t effect_index) {
diff --git a/esphome/components/light/light_state.h b/esphome/components/light/light_state.h
index 83b9226d03..b8d72cc832 100644
--- a/esphome/components/light/light_state.h
+++ b/esphome/components/light/light_state.h
@@ -11,7 +11,9 @@
 #include "light_traits.h"
 #include "light_transformer.h"
 
+#include "esphome/core/hal.h"
 #include "esphome/core/helpers.h"
+#include "esphome/core/progmem.h"
 #include <strings.h>
 #include <vector>
 
@@ -166,6 +168,23 @@ class LightState : public EntityBase, public Component {
   void set_gamma_correct(float gamma_correct);
   float get_gamma_correct() const { return this->gamma_correct_; }
 
+#ifdef USE_LIGHT_GAMMA_LUT
+  /// Set pre-computed gamma forward lookup table (256-entry uint16 PROGMEM array)
+  void set_gamma_table(const uint16_t *forward) { this->gamma_table_ = forward; }
+
+  /// Get the forward gamma lookup table
+  const uint16_t *get_gamma_table() const { return this->gamma_table_; }
+
+  /// Apply gamma correction using the pre-computed forward LUT
+  float gamma_correct_lut(float value) const;
+  /// Reverse gamma correction by binary-searching the forward LUT
+  float gamma_uncorrect_lut(float value) const;
+#else
+  /// No gamma LUT — passthrough
+  float gamma_correct_lut(float value) const { return value; }
+  float gamma_uncorrect_lut(float value) const { return value; }
+#endif  // USE_LIGHT_GAMMA_LUT
+
   /// Set the restore mode of this light
   void set_restore_mode(LightRestoreMode restore_mode);
 
@@ -200,6 +219,20 @@ class LightState : public EntityBase, public Component {
     return 0;  // Effect not found
   }
 
+  /// Get effect index by name (const char* overload, avoids std::string construction).
+  uint32_t get_effect_index(const char *name, size_t len) const {
+    if (len == 4 && ESPHOME_strncasecmp_P(name, ESPHOME_PSTR("none"), 4) == 0) {
+      return 0;
+    }
+    StringRef ref(name, len);
+    for (size_t i = 0; i < this->effects_.size(); i++) {
+      if (str_equals_case_insensitive(ref, this->effects_[i]->get_name())) {
+        return i + 1;
+      }
+    }
+    return 0;
+  }
+
   /// Get effect by index. Returns nullptr if index is invalid.
   LightEffect *get_effect_by_index(uint32_t index) const {
     if (index == 0 || index > this->effects_.size()) {
@@ -224,9 +257,9 @@ class LightState : public EntityBase, public Component {
 
   void current_values_as_brightness(float *brightness);
 
-  void current_values_as_rgb(float *red, float *green, float *blue, bool color_interlock = false);
+  void current_values_as_rgb(float *red, float *green, float *blue);
 
-  void current_values_as_rgbw(float *red, float *green, float *blue, float *white, bool color_interlock = false);
+  void current_values_as_rgbw(float *red, float *green, float *blue, float *white);
 
   void current_values_as_rgbww(float *red, float *green, float *blue, float *cold_white, float *warm_white,
                                bool constant_brightness = false);
@@ -297,6 +330,10 @@ class LightState : public EntityBase, public Component {
   uint32_t flash_transition_length_{};
   /// Gamma correction factor for the light.
   float gamma_correct_{};
+#ifdef USE_LIGHT_GAMMA_LUT
+  const uint16_t *gamma_table_{nullptr};
+#endif  // USE_LIGHT_GAMMA_LUT
+
   /// Whether the light value should be written in the next cycle.
   bool next_write_{true};
   // for effects, true if a transformer (transition) is active.
diff --git a/esphome/components/logger/__init__.py b/esphome/components/logger/__init__.py
index 264197c175..026b8aaf24 100644
--- a/esphome/components/logger/__init__.py
+++ b/esphome/components/logger/__init__.py
@@ -519,7 +519,9 @@ LOGGER_LOG_ACTION_SCHEMA = cv.All(
 )
 
 
-@automation.register_action(CONF_LOGGER_LOG, LambdaAction, LOGGER_LOG_ACTION_SCHEMA)
+@automation.register_action(
+    CONF_LOGGER_LOG, LambdaAction, LOGGER_LOG_ACTION_SCHEMA, synchronous=True
+)
 async def logger_log_action_to_code(config, action_id, template_arg, args):
     esp_log = LOG_LEVEL_TO_ESP_LOG[config[CONF_LEVEL]]
     args_ = [cg.RawExpression(str(x)) for x in config[CONF_ARGS]]
diff --git a/esphome/components/lvgl/light/lvgl_light.h b/esphome/components/lvgl/light/lvgl_light.h
index 50ae4c5327..569f9a03c0 100644
--- a/esphome/components/lvgl/light/lvgl_light.h
+++ b/esphome/components/lvgl/light/lvgl_light.h
@@ -16,7 +16,7 @@ class LVLight : public light::LightOutput {
   }
   void write_state(light::LightState *state) override {
     float red, green, blue;
-    state->current_values_as_rgb(&red, &green, &blue, false);
+    state->current_values_as_rgb(&red, &green, &blue);
     auto color = lv_color_make(red * 255, green * 255, blue * 255);
     if (this->obj_ != nullptr) {
       this->set_value_(color);
diff --git a/esphome/components/mqtt/__init__.py b/esphome/components/mqtt/__init__.py
index 44e8836487..c25c472038 100644
--- a/esphome/components/mqtt/__init__.py
+++ b/esphome/components/mqtt/__init__.py
@@ -492,7 +492,7 @@ MQTT_PUBLISH_ACTION_SCHEMA = cv.Schema(
 
 
 @automation.register_action(
-    "mqtt.publish", MQTTPublishAction, MQTT_PUBLISH_ACTION_SCHEMA
+    "mqtt.publish", MQTTPublishAction, MQTT_PUBLISH_ACTION_SCHEMA, synchronous=True
 )
 async def mqtt_publish_action_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -521,7 +521,10 @@ MQTT_PUBLISH_JSON_ACTION_SCHEMA = cv.Schema(
 
 
 @automation.register_action(
-    "mqtt.publish_json", MQTTPublishJsonAction, MQTT_PUBLISH_JSON_ACTION_SCHEMA
+    "mqtt.publish_json",
+    MQTTPublishJsonAction,
+    MQTT_PUBLISH_JSON_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def mqtt_publish_json_action_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
diff --git a/esphome/components/number/__init__.py b/esphome/components/number/__init__.py
index d12ec7463b..2238f2c037 100644
--- a/esphome/components/number/__init__.py
+++ b/esphome/components/number/__init__.py
@@ -352,6 +352,7 @@ OPERATION_BASE_SCHEMA = cv.Schema(
             cv.Required(CONF_VALUE): cv.templatable(cv.float_),
         }
     ),
+    synchronous=True,
 )
 async def number_set_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -374,6 +375,7 @@ async def number_set_to_code(config, action_id, template_arg, args):
             }
         )
     ),
+    synchronous=True,
 )
 @automation.register_action(
     "number.decrement",
@@ -388,6 +390,7 @@ async def number_set_to_code(config, action_id, template_arg, args):
             }
         )
     ),
+    synchronous=True,
 )
 @automation.register_action(
     "number.to_min",
@@ -401,6 +404,7 @@ async def number_set_to_code(config, action_id, template_arg, args):
             }
         )
     ),
+    synchronous=True,
 )
 @automation.register_action(
     "number.to_max",
@@ -414,6 +418,7 @@ async def number_set_to_code(config, action_id, template_arg, args):
             }
         )
     ),
+    synchronous=True,
 )
 @automation.register_action(
     "number.operation",
@@ -426,6 +431,7 @@ async def number_set_to_code(config, action_id, template_arg, args):
             cv.Optional(CONF_CYCLE, default=True): cv.templatable(cv.boolean),
         }
     ),
+    synchronous=True,
 )
 async def number_to_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
diff --git a/esphome/components/openthread/__init__.py b/esphome/components/openthread/__init__.py
index 89d335c574..5861c3db3f 100644
--- a/esphome/components/openthread/__init__.py
+++ b/esphome/components/openthread/__init__.py
@@ -52,6 +52,11 @@ def set_sdkconfig_options(config):
 
     # There is a conflict if the logger's uart also uses the default UART, which is seen as a watchdog failure on "ot_cli"
     add_idf_sdkconfig_option("CONFIG_OPENTHREAD_CLI", False)
+    # Console is the transport layer for CLI; disable it too since CLI is disabled
+    add_idf_sdkconfig_option("CONFIG_OPENTHREAD_CONSOLE_ENABLE", False)
+
+    # Diag unused, if needed for lab/cert/etc tests then enable separately
+    add_idf_sdkconfig_option("CONFIG_OPENTHREAD_DIAG", False)
 
     add_idf_sdkconfig_option("CONFIG_OPENTHREAD_ENABLED", True)
 
diff --git a/esphome/components/output/__init__.py b/esphome/components/output/__init__.py
index bde106b085..a4c960927b 100644
--- a/esphome/components/output/__init__.py
+++ b/esphome/components/output/__init__.py
@@ -74,14 +74,16 @@ BINARY_OUTPUT_ACTION_SCHEMA = maybe_simple_id(
 )
 
 
-@automation.register_action("output.turn_on", TurnOnAction, BINARY_OUTPUT_ACTION_SCHEMA)
+@automation.register_action(
+    "output.turn_on", TurnOnAction, BINARY_OUTPUT_ACTION_SCHEMA, synchronous=True
+)
 async def output_turn_on_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
     return cg.new_Pvariable(action_id, template_arg, paren)
 
 
 @automation.register_action(
-    "output.turn_off", TurnOffAction, BINARY_OUTPUT_ACTION_SCHEMA
+    "output.turn_off", TurnOffAction, BINARY_OUTPUT_ACTION_SCHEMA, synchronous=True
 )
 async def output_turn_off_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -97,6 +99,7 @@ async def output_turn_off_to_code(config, action_id, template_arg, args):
             cv.Required(CONF_LEVEL): cv.templatable(cv.percentage),
         }
     ),
+    synchronous=True,
 )
 async def output_set_level_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
diff --git a/esphome/components/rgb/rgb_light_output.h b/esphome/components/rgb/rgb_light_output.h
index ef53c8042d..783187667a 100644
--- a/esphome/components/rgb/rgb_light_output.h
+++ b/esphome/components/rgb/rgb_light_output.h
@@ -20,7 +20,7 @@ class RGBLightOutput : public light::LightOutput {
   }
   void write_state(light::LightState *state) override {
     float red, green, blue;
-    state->current_values_as_rgb(&red, &green, &blue, false);
+    state->current_values_as_rgb(&red, &green, &blue);
     this->red_->set_level(red);
     this->green_->set_level(green);
     this->blue_->set_level(blue);
diff --git a/esphome/components/rgbw/rgbw_light_output.h b/esphome/components/rgbw/rgbw_light_output.h
index a2ab17b75d..140726a43c 100644
--- a/esphome/components/rgbw/rgbw_light_output.h
+++ b/esphome/components/rgbw/rgbw_light_output.h
@@ -25,7 +25,7 @@ class RGBWLightOutput : public light::LightOutput {
   }
   void write_state(light::LightState *state) override {
     float red, green, blue, white;
-    state->current_values_as_rgbw(&red, &green, &blue, &white, this->color_interlock_);
+    state->current_values_as_rgbw(&red, &green, &blue, &white);
     this->red_->set_level(red);
     this->green_->set_level(green);
     this->blue_->set_level(blue);
diff --git a/esphome/components/rp2040/__init__.py b/esphome/components/rp2040/__init__.py
index 23f12e651f..ea269a47c5 100644
--- a/esphome/components/rp2040/__init__.py
+++ b/esphome/components/rp2040/__init__.py
@@ -169,6 +169,7 @@ async def to_code(config):
     cg.add_platformio_option("lib_compat_mode", "strict")
     cg.add_platformio_option("board", config[CONF_BOARD])
     cg.add_build_flag("-DUSE_RP2040")
+    cg.add_define("USE_NATIVE_64BIT_TIME")
     cg.set_cpp_standard("gnu++20")
     cg.add_define("ESPHOME_BOARD", config[CONF_BOARD])
     cg.add_define("ESPHOME_VARIANT", "RP2040")
diff --git a/esphome/components/rp2040/core.cpp b/esphome/components/rp2040/core.cpp
index 8b86de4be1..6386d53292 100644
--- a/esphome/components/rp2040/core.cpp
+++ b/esphome/components/rp2040/core.cpp
@@ -34,6 +34,7 @@ void HOT arch_feed_wdt() { watchdog_update(); }
 uint8_t progmem_read_byte(const uint8_t *addr) {
   return pgm_read_byte(addr);  // NOLINT
 }
+uint16_t progmem_read_uint16(const uint16_t *addr) { return *addr; }
 uint32_t HOT arch_get_cpu_cycle_count() { return ulMainGetRunTimeCounterValue(); }
 uint32_t arch_get_cpu_freq_hz() { return RP2040::f_cpu(); }
 
diff --git a/esphome/components/rtttl/rtttl.cpp b/esphome/components/rtttl/rtttl.cpp
index ab95067f45..4ccfc539ea 100644
--- a/esphome/components/rtttl/rtttl.cpp
+++ b/esphome/components/rtttl/rtttl.cpp
@@ -8,18 +8,26 @@ namespace esphome::rtttl {
 
 static const char *const TAG = "rtttl";
 
-// These values can also be found as constants in the Tone library (Tone.h)
-static const uint16_t NOTES[] = {0,    262,  277,  294,  311,  330,  349,  370,  392,  415,  440,  466,  494,
-                                 523,  554,  587,  622,  659,  698,  740,  784,  831,  880,  932,  988,  1047,
-                                 1109, 1175, 1245, 1319, 1397, 1480, 1568, 1661, 1760, 1865, 1976, 2093, 2217,
-                                 2349, 2489, 2637, 2794, 2960, 3136, 3322, 3520, 3729, 3951};
+static constexpr uint8_t SONG_NAME_LENGTH_LIMIT = 64;
+static constexpr uint8_t SEMITONES_IN_OCTAVE = 12;
 
-#if defined(USE_OUTPUT) || defined(USE_SPEAKER)
-static const uint32_t DOUBLE_NOTE_GAP_MS = 10;
-#endif  // USE_OUTPUT || USE_SPEAKER
+static constexpr uint8_t MIN_OCTAVE = 4;
+static constexpr uint8_t MAX_OCTAVE = 7;
+
+static constexpr uint8_t DEFAULT_BPM = 63;  // Default beats per minute
+
+// These values can also be found as constants in the Tone library (Tone.h)
+static constexpr uint16_t NOTES[] = {0,    262,  277,  294,  311,  330,  349,  370,  392,  415,  440,  466,  494,
+                                     523,  554,  587,  622,  659,  698,  740,  784,  831,  880,  932,  988,  1047,
+                                     1109, 1175, 1245, 1319, 1397, 1480, 1568, 1661, 1760, 1865, 1976, 2093, 2217,
+                                     2349, 2489, 2637, 2794, 2960, 3136, 3322, 3520, 3729, 3951};
+static constexpr uint8_t NOTES_COUNT = static_cast<uint8_t>(sizeof(NOTES) / sizeof(NOTES[0]));
+
+static constexpr uint8_t REPEATING_NOTE_GAP_MS = 10;
 
 #ifdef USE_SPEAKER
-static const size_t SAMPLE_BUFFER_SIZE = 2048;
+static constexpr uint16_t SAMPLE_BUFFER_SIZE = 2048;
+static constexpr uint16_t SAMPLE_RATE = 16000;
 
 struct SpeakerSample {
   int8_t left{0};
@@ -27,7 +35,7 @@ struct SpeakerSample {
 };
 
 inline double deg2rad(double degrees) {
-  static const double PI_ON_180 = 4.0 * atan(1.0) / 180.0;
+  static constexpr double PI_ON_180 = M_PI / 180.0;
   return degrees * PI_ON_180;
 }
 #endif  // USE_SPEAKER
@@ -85,7 +93,7 @@ void Rtttl::loop() {
   }
 
 #ifdef USE_OUTPUT
-  if (this->output_ != nullptr && millis() - this->last_note_ < this->note_duration_) {
+  if (this->output_ != nullptr && millis() - this->last_note_start_time_ < this->note_duration_) {
     return;
   }
 #endif  // USE_OUTPUT
@@ -113,36 +121,34 @@ void Rtttl::loop() {
     }
     if (this->samples_sent_ != this->samples_count_) {
       SpeakerSample sample[SAMPLE_BUFFER_SIZE + 2];
-      int x = 0;
+      uint16_t sample_index = 0;
       double rem = 0.0;
 
       while (true) {
-        // Try and send out the remainder of the existing note, one per loop()
-
-        if (this->samples_per_wave_ != 0 && this->samples_sent_ >= this->samples_gap_) {  // Play note//
+        // Try and send out the remainder of the existing note, one per `loop()`
+        if (this->samples_per_wave_ != 0 && this->samples_sent_ >= this->samples_gap_) {  // Play note
           rem = ((this->samples_sent_ << 10) % this->samples_per_wave_) * (360.0 / this->samples_per_wave_);
 
-          int16_t val = (127 * this->gain_) * sin(deg2rad(rem));  // 16bit = 49152
-
-          sample[x].left = val;
-          sample[x].right = val;
+          int8_t val = (127 * this->gain_) * sin(deg2rad(rem));
 
+          sample[sample_index].left = val;
+          sample[sample_index].right = val;
         } else {
-          sample[x].left = 0;
-          sample[x].right = 0;
+          sample[sample_index].left = 0;
+          sample[sample_index].right = 0;
         }
 
-        if (static_cast<size_t>(x) >= SAMPLE_BUFFER_SIZE || this->samples_sent_ >= this->samples_count_) {
+        if (sample_index >= SAMPLE_BUFFER_SIZE || this->samples_sent_ >= this->samples_count_) {
           break;
         }
         this->samples_sent_++;
-        x++;
+        sample_index++;
       }
-      if (x > 0) {
-        size_t bytes_to_send = x * sizeof(SpeakerSample);
+      if (sample_index > 0) {
+        size_t bytes_to_send = sample_index * sizeof(SpeakerSample);
         size_t send = this->speaker_->play((uint8_t *) (&sample), bytes_to_send);
         if (send != bytes_to_send) {
-          this->samples_sent_ -= (x - (send / sizeof(SpeakerSample)));
+          this->samples_sent_ -= (sample_index - (send / sizeof(SpeakerSample)));
         }
         return;
       }
@@ -155,83 +161,84 @@ void Rtttl::loop() {
     return;
   }
 
-  // align to note: most rtttl's out there does not add and space after the ',' separator but just in case...
+  // Align to note: most rtttl's out there does not add any space after the ',' separator but just in case
   while (this->rtttl_[this->position_] == ',' || this->rtttl_[this->position_] == ' ') {
     this->position_++;
   }
 
-  // first, get note duration, if available
-  uint8_t num = this->get_integer_();
+  // First, get note duration, if available
+  uint8_t note_denominator = this->get_integer_();
 
-  if (num) {
-    this->note_duration_ = this->wholenote_ / num;
+  if (note_denominator) {
+    this->note_duration_ = this->wholenote_duration_ / note_denominator;
   } else {
-    this->note_duration_ =
-        this->wholenote_ / this->default_duration_;  // we will need to check if we are a dotted note after
+    // We will need to check if we are a dotted note after
+    this->note_duration_ = this->wholenote_duration_ / this->default_note_denominator_;
   }
 
-  uint8_t note = note_index_from_char(this->rtttl_[this->position_]);
+  uint8_t note_index_in_octave = note_index_from_char(this->rtttl_[this->position_]);
 
   this->position_++;
 
-  // now, get optional '#' sharp
+  // Now, get optional '#' sharp
   if (this->rtttl_[this->position_] == '#') {
-    note++;
+    note_index_in_octave++;
     this->position_++;
   }
 
-  // now, get scale
+  // Now, get scale
   uint8_t scale = this->get_integer_();
   if (scale == 0) {
     scale = this->default_octave_;
   }
 
-  if (scale < 4 || scale > 7) {
-    ESP_LOGE(TAG, "Octave must be between 4 and 7 (it is %d)", scale);
+  if (scale < MIN_OCTAVE || scale > MAX_OCTAVE) {
+    ESP_LOGE(TAG, "Octave must be between %d and %d (it is %d)", MIN_OCTAVE, MAX_OCTAVE, scale);
     this->finish_();
     return;
   }
 
-  // now, get optional '.' dotted note
+  // Now, get optional '.' dotted note
   if (this->rtttl_[this->position_] == '.') {
-    this->note_duration_ += this->note_duration_ / 2;
+    this->note_duration_ += this->note_duration_ / 2;  // Duration +50%
     this->position_++;
   }
 
-  // Now play the note
   bool need_note_gap = false;
-  if (note) {
-    auto note_index = (scale - 4) * 12 + note;
-    if (note_index < 0 || note_index >= (int) (sizeof(NOTES) / sizeof(NOTES[0]))) {
-      ESP_LOGE(TAG, "Note out of range (note: %d, scale: %d, index: %d, max: %d)", note, scale, note_index,
-               (int) (sizeof(NOTES) / sizeof(NOTES[0])));
+
+  // Now play the note
+  if (note_index_in_octave == 0) {
+    this->output_freq_ = 0;
+    ESP_LOGVV(TAG, "Waiting: %dms", this->note_duration_);
+  } else {
+    uint8_t note_index = (scale - MIN_OCTAVE) * SEMITONES_IN_OCTAVE + note_index_in_octave;
+    if (note_index >= NOTES_COUNT) {
+      ESP_LOGE(TAG, "Note out of range (note: %d, scale: %d, index: %d, max: %d)", note_index_in_octave, scale,
+               note_index, NOTES_COUNT);
       this->finish_();
       return;
     }
-    auto freq = NOTES[note_index];
+    uint16_t freq = NOTES[note_index];
     need_note_gap = freq == this->output_freq_;
 
     // Add small silence gap between same note
     this->output_freq_ = freq;
 
-    ESP_LOGVV(TAG, "playing note: %d for %dms", note, this->note_duration_);
-  } else {
-    ESP_LOGVV(TAG, "waiting: %dms", this->note_duration_);
-    this->output_freq_ = 0;
+    ESP_LOGVV(TAG, "Playing note: %d for %dms", note_index_in_octave, this->note_duration_);
   }
 
 #ifdef USE_OUTPUT
   if (this->output_ != nullptr) {
-    if (need_note_gap && this->note_duration_ > DOUBLE_NOTE_GAP_MS) {
+    if (this->output_freq_ == 0) {
       this->output_->set_level(0.0);
-      delay(DOUBLE_NOTE_GAP_MS);
-      this->note_duration_ -= DOUBLE_NOTE_GAP_MS;
-    }
-    if (this->output_freq_ != 0) {
+    } else {
+      if (need_note_gap && this->note_duration_ > REPEATING_NOTE_GAP_MS) {
+        this->output_->set_level(0.0);
+        delay(REPEATING_NOTE_GAP_MS);
+        this->note_duration_ -= REPEATING_NOTE_GAP_MS;
+      }
       this->output_->update_frequency(this->output_freq_);
       this->output_->set_level(this->gain_);
-    } else {
-      this->output_->set_level(0.0);
     }
   }
 #endif  // USE_OUTPUT
@@ -241,28 +248,26 @@ void Rtttl::loop() {
     this->samples_sent_ = 0;
     this->samples_gap_ = 0;
     this->samples_per_wave_ = 0;
-    this->samples_count_ = (this->sample_rate_ * this->note_duration_) / 1000;
+    this->samples_count_ = (SAMPLE_RATE * this->note_duration_) / 1000;
     if (need_note_gap) {
-      this->samples_gap_ = (this->sample_rate_ * DOUBLE_NOTE_GAP_MS) / 1000;
+      this->samples_gap_ = (SAMPLE_RATE * REPEATING_NOTE_GAP_MS) / 1000;
     }
     if (this->output_freq_ != 0) {
-      // make sure there is enough samples to add a full last sinus.
-
-      uint16_t samples_wish = this->samples_count_;
-      this->samples_per_wave_ = (this->sample_rate_ << 10) / this->output_freq_;
+      // Make sure there is enough samples to add a full last sinus.
+      uint32_t samples_wish = this->samples_count_;
+      this->samples_per_wave_ = (SAMPLE_RATE << 10) / this->output_freq_;
 
       uint16_t division = ((this->samples_count_ << 10) / this->samples_per_wave_) + 1;
 
-      this->samples_count_ = (division * this->samples_per_wave_);
-      this->samples_count_ = this->samples_count_ >> 10;
-      ESP_LOGVV(TAG, "- Calc play time: wish: %d gets: %d (div: %d spw: %d)", samples_wish, this->samples_count_,
-                division, this->samples_per_wave_);
+      this->samples_count_ = (division * this->samples_per_wave_) >> 10;
+      ESP_LOGVV(TAG, "Calc play time: wish: %" PRIu32 " gets: %" PRIu32 " (div: %d spw: %" PRIu32 ")", samples_wish,
+                this->samples_count_, division, this->samples_per_wave_);
     }
     // Convert from frequency in Hz to high and low samples in fixed point
   }
 #endif  // USE_SPEAKER
 
-  this->last_note_ = millis();
+  this->last_note_start_time_ = millis();
 }
 
 void Rtttl::play(std::string rtttl) {
@@ -275,25 +280,28 @@ void Rtttl::play(std::string rtttl) {
 
   this->rtttl_ = std::move(rtttl);
 
-  this->default_duration_ = 4;
-  this->default_octave_ = 6;
+  this->default_note_denominator_ = DEFAULT_NOTE_DENOMINATOR;
+  this->default_octave_ = DEFAULT_OCTAVE;
   this->note_duration_ = 0;
 
-  int bpm = 63;
-  uint16_t num;
+  uint16_t bpm = DEFAULT_BPM;
+  uint16_t num;  // Used for: default note-denominator, default octave, BPM
 
   // Get name
   this->position_ = this->rtttl_.find(':');
 
-  // it's somewhat documented to be up to 10 characters but let's be a bit flexible here
-  if (this->position_ == std::string::npos || this->position_ > 15) {
+  if (this->position_ == std::string::npos) {
     ESP_LOGE(TAG, "Unable to determine name; missing ':'");
     return;
   }
-
+  if (this->position_ >= SONG_NAME_LENGTH_LIMIT) {
+    ESP_LOGE(TAG, "Name is too long: length=%u, limit=%u", static_cast<unsigned>(this->position_),
+             static_cast<unsigned>(SONG_NAME_LENGTH_LIMIT));
+    return;
+  }
   ESP_LOGD(TAG, "Playing song %.*s", (int) this->position_, this->rtttl_.c_str());
 
-  // get default duration
+  // Get default duration
   this->position_ = this->rtttl_.find("d=", this->position_);
   if (this->position_ == std::string::npos) {
     ESP_LOGE(TAG, "Missing 'd='");
@@ -301,11 +309,14 @@ void Rtttl::play(std::string rtttl) {
   }
   this->position_ += 2;
   num = this->get_integer_();
-  if (num > 0) {
-    this->default_duration_ = num;
+  if (num == 1 || num == 2 || num == 4 || num == 8 || num == 16 || num == 32) {
+    this->default_note_denominator_ = num;
+  } else {
+    ESP_LOGE(TAG, "Invalid default duration: %d", num);
+    return;
   }
 
-  // get default octave
+  // Get default octave
   this->position_ = this->rtttl_.find("o=", this->position_);
   if (this->position_ == std::string::npos) {
     ESP_LOGE(TAG, "Missing 'o=");
@@ -313,11 +324,14 @@ void Rtttl::play(std::string rtttl) {
   }
   this->position_ += 2;
   num = this->get_integer_();
-  if (num >= 3 && num <= 7) {
+  if (num >= MIN_OCTAVE && num <= MAX_OCTAVE) {
     this->default_octave_ = num;
+  } else {
+    ESP_LOGE(TAG, "Invalid default octave: %d", num);
+    return;
   }
 
-  // get BPM
+  // Get BPM
   this->position_ = this->rtttl_.find("b=", this->position_);
   if (this->position_ == std::string::npos) {
     ESP_LOGE(TAG, "Missing b=");
@@ -325,8 +339,11 @@ void Rtttl::play(std::string rtttl) {
   }
   this->position_ += 2;
   num = this->get_integer_();
-  if (num != 0) {
+  if (num >= 4) {  // Below 4 is not realistic and would cause a integer overflow
     bpm = num;
+  } else {
+    ESP_LOGE(TAG, "Invalid BPM: %d", num);
+    return;
   }
 
   this->position_ = this->rtttl_.find(':', this->position_);
@@ -337,10 +354,10 @@ void Rtttl::play(std::string rtttl) {
   this->position_++;
 
   // BPM usually expresses the number of quarter notes per minute
-  this->wholenote_ = 60 * 1000L * 4 / bpm;  // this is the time for whole note (in milliseconds)
+  this->wholenote_duration_ = 60 * 1000L * 4 / bpm;  // This is the time for whole note (in milliseconds)
 
   this->output_freq_ = 0;
-  this->last_note_ = millis();
+  this->last_note_start_time_ = millis();
   this->note_duration_ = 1;
 
 #ifdef USE_OUTPUT
diff --git a/esphome/components/rtttl/rtttl.h b/esphome/components/rtttl/rtttl.h
index 4d4a652c51..e37cccae9e 100644
--- a/esphome/components/rtttl/rtttl.h
+++ b/esphome/components/rtttl/rtttl.h
@@ -13,6 +13,10 @@
 
 namespace esphome::rtttl {
 
+inline constexpr uint8_t DEFAULT_NOTE_DENOMINATOR = 4;  // Default note-denominator (quarter note)
+inline constexpr uint8_t DEFAULT_OCTAVE =
+    6;  // Default octave for a note (see: `MIN_OCTAVE`, `MAX_OCTAVE` in `rtttl.cpp`)
+
 enum class State : uint8_t {
   STOPPED = 0,
   INIT,
@@ -67,19 +71,18 @@ class Rtttl : public Component {
   std::string rtttl_{""};
   /// The current position in the RTTTL string.
   size_t position_{0};
-  /// The duration of a whole note in milliseconds.
-  uint16_t wholenote_;
   /// The default duration of a note (e.g. 4 for a quarter note).
-  uint16_t default_duration_;
+  uint8_t default_note_denominator_{DEFAULT_NOTE_DENOMINATOR};
   /// The default octave for a note.
-  uint16_t default_octave_;
-  /// The time the last note was started.
-  uint32_t last_note_;
+  uint8_t default_octave_{DEFAULT_OCTAVE};
   /// The duration of the current note in milliseconds.
-  uint16_t note_duration_;
-
+  uint16_t note_duration_{0};
+  /// The duration of a whole note in milliseconds.
+  uint16_t wholenote_duration_;
+  /// The time in milliseconds since microcontroller boot when the last note was started.
+  uint32_t last_note_start_time_;
   /// The frequency of the current note in Hz.
-  uint32_t output_freq_;
+  uint32_t output_freq_{0};
   /// The gain of the output.
   float gain_{0.6f};
   /// The current state of the RTTTL player.
@@ -93,16 +96,14 @@ class Rtttl : public Component {
 #ifdef USE_SPEAKER
   /// The speaker to write the sound to.
   speaker::Speaker *speaker_{nullptr};
-  /// The sample rate of the speaker.
-  int sample_rate_{16000};
   /// The number of samples for one full cycle of a note's waveform, in Q10 fixed-point format.
-  int samples_per_wave_{0};
+  uint32_t samples_per_wave_{0};
   /// The number of samples sent.
-  int samples_sent_{0};
+  uint32_t samples_sent_{0};
   /// The total number of samples to send.
-  int samples_count_{0};
+  uint32_t samples_count_{0};
   /// The number of samples for the gap between notes.
-  int samples_gap_{0};
+  uint32_t samples_gap_{0};
 #endif  // USE_SPEAKER
 
   /// The callback to call when playback is finished.
diff --git a/esphome/components/script/__init__.py b/esphome/components/script/__init__.py
index 8d69981db0..369cefad91 100644
--- a/esphome/components/script/__init__.py
+++ b/esphome/components/script/__init__.py
@@ -160,6 +160,7 @@ async def to_code(config):
             cv.Optional(validate_parameter_name): cv.templatable(cv.valid),
         },
     ),
+    synchronous=True,
 )
 async def script_execute_action_to_code(config, action_id, template_arg, args):
     def convert(type: str):
@@ -208,6 +209,7 @@ async def script_execute_action_to_code(config, action_id, template_arg, args):
     "script.stop",
     ScriptStopAction,
     maybe_simple_id({cv.Required(CONF_ID): cv.use_id(Script)}),
+    synchronous=True,
 )
 async def script_stop_action_to_code(config, action_id, template_arg, args):
     full_id, paren = await cg.get_variable_with_full_id(config[CONF_ID])
diff --git a/esphome/components/select/__init__.py b/esphome/components/select/__init__.py
index 84ad591ba1..c114b140a9 100644
--- a/esphome/components/select/__init__.py
+++ b/esphome/components/select/__init__.py
@@ -145,6 +145,7 @@ OPERATION_BASE_SCHEMA = cv.Schema(
             cv.Required(CONF_OPTION): cv.templatable(cv.string_strict),
         }
     ),
+    synchronous=True,
 )
 async def select_set_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -162,6 +163,7 @@ async def select_set_to_code(config, action_id, template_arg, args):
             cv.Required(CONF_INDEX): cv.templatable(cv.positive_int),
         }
     ),
+    synchronous=True,
 )
 async def select_set_index_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -217,6 +219,7 @@ async def select_is_to_code(config, condition_id, template_arg, args):
             cv.Optional(CONF_CYCLE, default=True): cv.templatable(cv.boolean),
         }
     ),
+    synchronous=True,
 )
 @automation.register_action(
     "select.next",
@@ -229,6 +232,7 @@ async def select_is_to_code(config, condition_id, template_arg, args):
             }
         )
     ),
+    synchronous=True,
 )
 @automation.register_action(
     "select.previous",
@@ -243,6 +247,7 @@ async def select_is_to_code(config, condition_id, template_arg, args):
             }
         )
     ),
+    synchronous=True,
 )
 @automation.register_action(
     "select.first",
@@ -254,6 +259,7 @@ async def select_is_to_code(config, condition_id, template_arg, args):
             }
         )
     ),
+    synchronous=True,
 )
 @automation.register_action(
     "select.last",
@@ -265,6 +271,7 @@ async def select_is_to_code(config, condition_id, template_arg, args):
             }
         )
     ),
+    synchronous=True,
 )
 async def select_operation_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
diff --git a/esphome/components/socket/__init__.py b/esphome/components/socket/__init__.py
index a83648979c..08cf3ea33c 100644
--- a/esphome/components/socket/__init__.py
+++ b/esphome/components/socket/__init__.py
@@ -189,9 +189,10 @@ async def to_code(config):
         cg.add_define("USE_SOCKET_IMPL_BSD_SOCKETS")
         cg.add_define("USE_SOCKET_SELECT_SUPPORT")
     # ESP32 and LibreTiny both have LwIP >= 2.1.3 with lwip_socket_dbg_get_socket()
-    # and FreeRTOS task notifications — enable fast select to bypass lwip_select()
-    if CORE.is_esp32 or CORE.is_libretiny:
-        cg.add_define("USE_LWIP_FAST_SELECT")
+    # and FreeRTOS task notifications — enable fast select to bypass lwip_select().
+    # Only when not using lwip_tcp, which does not provide select() support.
+    if (CORE.is_esp32 or CORE.is_libretiny) and impl != IMPLEMENTATION_LWIP_TCP:
+        cg.add_build_flag("-DUSE_LWIP_FAST_SELECT")
 
 
 def FILTER_SOURCE_FILES() -> list[str]:
diff --git a/esphome/components/switch/__init__.py b/esphome/components/switch/__init__.py
index cfc5e2b6e8..6f1be7d53d 100644
--- a/esphome/components/switch/__init__.py
+++ b/esphome/components/switch/__init__.py
@@ -204,7 +204,7 @@ SWITCH_CONTROL_ACTION_SCHEMA = automation.maybe_simple_id(
 
 
 @automation.register_action(
-    "switch.control", ControlAction, SWITCH_CONTROL_ACTION_SCHEMA
+    "switch.control", ControlAction, SWITCH_CONTROL_ACTION_SCHEMA, synchronous=True
 )
 async def switch_control_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -214,9 +214,15 @@ async def switch_control_to_code(config, action_id, template_arg, args):
     return var
 
 
-@automation.register_action("switch.toggle", ToggleAction, SWITCH_ACTION_SCHEMA)
-@automation.register_action("switch.turn_off", TurnOffAction, SWITCH_ACTION_SCHEMA)
-@automation.register_action("switch.turn_on", TurnOnAction, SWITCH_ACTION_SCHEMA)
+@automation.register_action(
+    "switch.toggle", ToggleAction, SWITCH_ACTION_SCHEMA, synchronous=True
+)
+@automation.register_action(
+    "switch.turn_off", TurnOffAction, SWITCH_ACTION_SCHEMA, synchronous=True
+)
+@automation.register_action(
+    "switch.turn_on", TurnOnAction, SWITCH_ACTION_SCHEMA, synchronous=True
+)
 async def switch_toggle_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
     return cg.new_Pvariable(action_id, template_arg, paren)
diff --git a/esphome/components/text/__init__.py b/esphome/components/text/__init__.py
index 9ceea0dfdf..61f7119cad 100644
--- a/esphome/components/text/__init__.py
+++ b/esphome/components/text/__init__.py
@@ -164,6 +164,7 @@ OPERATION_BASE_SCHEMA = cv.Schema(
             cv.Required(CONF_VALUE): cv.templatable(cv.string_strict),
         }
     ),
+    synchronous=True,
 )
 async def text_set_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
diff --git a/esphome/components/text/text_call.cpp b/esphome/components/text/text_call.cpp
index 8a1630c5ca..b7aed098c7 100644
--- a/esphome/components/text/text_call.cpp
+++ b/esphome/components/text/text_call.cpp
@@ -11,6 +11,11 @@ TextCall &TextCall::set_value(const std::string &value) {
   return *this;
 }
 
+TextCall &TextCall::set_value(const char *value, size_t len) {
+  this->value_ = std::string(value, len);
+  return *this;
+}
+
 void TextCall::validate_() {
   const auto *name = this->parent_->get_name().c_str();
 
diff --git a/esphome/components/text/text_call.h b/esphome/components/text/text_call.h
index 532fae34b2..5a2b257ab2 100644
--- a/esphome/components/text/text_call.h
+++ b/esphome/components/text/text_call.h
@@ -13,6 +13,7 @@ class TextCall {
   void perform();
 
   TextCall &set_value(const std::string &value);
+  TextCall &set_value(const char *value, size_t len);
 
  protected:
   Text *const parent_;
diff --git a/esphome/components/time/__init__.py b/esphome/components/time/__init__.py
index a20d79b857..7ffa408db9 100644
--- a/esphome/components/time/__init__.py
+++ b/esphome/components/time/__init__.py
@@ -1,6 +1,10 @@
 from importlib import resources
 import logging
 
+from aioesphomeapi.posix_tz import (
+    DSTRuleType as PyDSTRuleType,
+    parse_posix_tz as parse_posix_tz_python,
+)
 import tzlocal
 
 from esphome import automation
@@ -39,6 +43,19 @@ CronTrigger = time_ns.class_("CronTrigger", automation.Trigger.template(), cg.Co
 SyncTrigger = time_ns.class_("SyncTrigger", automation.Trigger.template(), cg.Component)
 TimeHasTimeCondition = time_ns.class_("TimeHasTimeCondition", Condition)
 
+# C++ types for pre-parsed timezone struct generation
+DSTRuleType_cpp = time_ns.enum("DSTRuleType", is_class=True)
+DSTRule_cpp = time_ns.struct("DSTRule")
+ParsedTimezone_cpp = time_ns.struct("ParsedTimezone")
+
+# Map Python DSTRuleType enum values to C++ enum expressions
+_DST_RULE_TYPE_MAP = {
+    PyDSTRuleType.NONE: DSTRuleType_cpp.NONE,
+    PyDSTRuleType.MONTH_WEEK_DAY: DSTRuleType_cpp.MONTH_WEEK_DAY,
+    PyDSTRuleType.JULIAN_NO_LEAP: DSTRuleType_cpp.JULIAN_NO_LEAP,
+    PyDSTRuleType.DAY_OF_YEAR: DSTRuleType_cpp.DAY_OF_YEAR,
+}
+
 
 def _load_tzdata(iana_key: str) -> bytes | None:
     # From https://tzdata.readthedocs.io/en/latest/#examples
@@ -260,11 +277,17 @@ def validate_tz(value: str) -> str:
     value = cv.string_strict(value)
 
     tzfile = _load_tzdata(value)
-    if tzfile is None:
-        # Not a IANA key, probably a TZ string
-        return value
+    if tzfile is not None:
+        value = _extract_tz_string(tzfile)
 
-    return _extract_tz_string(tzfile)
+    # Validate that the POSIX TZ string is parseable (skip empty strings)
+    if value:
+        try:
+            parse_posix_tz_python(value)
+        except ValueError as e:
+            raise cv.Invalid(f"Invalid POSIX timezone string '{value}': {e}") from e
+
+    return value
 
 
 TIME_SCHEMA = cv.Schema(
@@ -305,11 +328,46 @@ TIME_SCHEMA = cv.Schema(
 ).extend(cv.polling_component_schema("15min"))
 
 
+def _emit_dst_rule_fields(prefix, rule):
+    """Emit field-by-field assignments for a DSTRule to avoid rodata struct blob."""
+    cg.add(cg.RawExpression(f"{prefix}.time_seconds = {rule.time_seconds}"))
+    cg.add(cg.RawExpression(f"{prefix}.day = {rule.day}"))
+    cg.add(cg.RawExpression(f"{prefix}.type = {_DST_RULE_TYPE_MAP[rule.type]}"))
+    cg.add(cg.RawExpression(f"{prefix}.month = {rule.month}"))
+    cg.add(cg.RawExpression(f"{prefix}.week = {rule.week}"))
+    cg.add(cg.RawExpression(f"{prefix}.day_of_week = {rule.day_of_week}"))
+
+
+def _emit_parsed_timezone_fields(parsed):
+    """Emit field-by-field assignments for a local ParsedTimezone, then set_global_tz().
+
+    Uses individual assignments on a stack variable instead of a struct initializer
+    to keep constants as immediate operands in instructions (.irom0.text/flash)
+    rather than a const blob in .rodata (which maps to RAM on ESP8266).
+    Wrapped in a scope block to allow multiple time platforms in the same build.
+    """
+    cg.add(cg.RawStatement("{"))
+    cg.add(cg.RawExpression("time::ParsedTimezone tz{}"))
+    cg.add(cg.RawExpression(f"tz.std_offset_seconds = {parsed.std_offset_seconds}"))
+    cg.add(cg.RawExpression(f"tz.dst_offset_seconds = {parsed.dst_offset_seconds}"))
+    _emit_dst_rule_fields("tz.dst_start", parsed.dst_start)
+    _emit_dst_rule_fields("tz.dst_end", parsed.dst_end)
+    cg.add(time_ns.set_global_tz(cg.RawExpression("tz")))
+    cg.add(cg.RawStatement("}"))
+
+
 async def setup_time_core_(time_var, config):
     if timezone := config.get(CONF_TIMEZONE):
-        cg.add(time_var.set_timezone(timezone))
         cg.add_define("USE_TIME_TIMEZONE")
 
+        if CORE.is_host:
+            # Host platform needs setenv("TZ")/tzset() for libc compatibility
+            cg.add(time_var.set_timezone(timezone))
+        else:
+            # Embedded: pre-parse at codegen time, emit struct directly
+            parsed = parse_posix_tz_python(timezone)
+            _emit_parsed_timezone_fields(parsed)
+
     for conf in config.get(CONF_ON_TIME, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], time_var)
 
diff --git a/esphome/components/water_heater/water_heater.cpp b/esphome/components/water_heater/water_heater.cpp
index 9d7ae0cbc0..3989230d2d 100644
--- a/esphome/components/water_heater/water_heater.cpp
+++ b/esphome/components/water_heater/water_heater.cpp
@@ -5,6 +5,7 @@
 #include "esphome/core/progmem.h"
 
 #include <cmath>
+#include <cstring>
 
 namespace esphome::water_heater {
 
@@ -23,23 +24,25 @@ WaterHeaterCall &WaterHeaterCall::set_mode(WaterHeaterMode mode) {
   return *this;
 }
 
-WaterHeaterCall &WaterHeaterCall::set_mode(const char *mode) {
-  if (ESPHOME_strcasecmp_P(mode, ESPHOME_PSTR("OFF")) == 0) {
+WaterHeaterCall &WaterHeaterCall::set_mode(const char *mode) { return this->set_mode(mode, strlen(mode)); }
+
+WaterHeaterCall &WaterHeaterCall::set_mode(const char *mode, size_t len) {
+  if (len == 3 && ESPHOME_strncasecmp_P(mode, ESPHOME_PSTR("OFF"), 3) == 0) {
     this->set_mode(WATER_HEATER_MODE_OFF);
-  } else if (ESPHOME_strcasecmp_P(mode, ESPHOME_PSTR("ECO")) == 0) {
+  } else if (len == 3 && ESPHOME_strncasecmp_P(mode, ESPHOME_PSTR("ECO"), 3) == 0) {
     this->set_mode(WATER_HEATER_MODE_ECO);
-  } else if (ESPHOME_strcasecmp_P(mode, ESPHOME_PSTR("ELECTRIC")) == 0) {
+  } else if (len == 8 && ESPHOME_strncasecmp_P(mode, ESPHOME_PSTR("ELECTRIC"), 8) == 0) {
     this->set_mode(WATER_HEATER_MODE_ELECTRIC);
-  } else if (ESPHOME_strcasecmp_P(mode, ESPHOME_PSTR("PERFORMANCE")) == 0) {
+  } else if (len == 11 && ESPHOME_strncasecmp_P(mode, ESPHOME_PSTR("PERFORMANCE"), 11) == 0) {
     this->set_mode(WATER_HEATER_MODE_PERFORMANCE);
-  } else if (ESPHOME_strcasecmp_P(mode, ESPHOME_PSTR("HIGH_DEMAND")) == 0) {
+  } else if (len == 11 && ESPHOME_strncasecmp_P(mode, ESPHOME_PSTR("HIGH_DEMAND"), 11) == 0) {
     this->set_mode(WATER_HEATER_MODE_HIGH_DEMAND);
-  } else if (ESPHOME_strcasecmp_P(mode, ESPHOME_PSTR("HEAT_PUMP")) == 0) {
+  } else if (len == 9 && ESPHOME_strncasecmp_P(mode, ESPHOME_PSTR("HEAT_PUMP"), 9) == 0) {
     this->set_mode(WATER_HEATER_MODE_HEAT_PUMP);
-  } else if (ESPHOME_strcasecmp_P(mode, ESPHOME_PSTR("GAS")) == 0) {
+  } else if (len == 3 && ESPHOME_strncasecmp_P(mode, ESPHOME_PSTR("GAS"), 3) == 0) {
     this->set_mode(WATER_HEATER_MODE_GAS);
   } else {
-    ESP_LOGW(TAG, "'%s' - Unrecognized mode %s", this->parent_->get_name().c_str(), mode);
+    ESP_LOGW(TAG, "'%s' - Unrecognized mode %.*s", this->parent_->get_name().c_str(), (int) len, mode);
   }
   return *this;
 }
diff --git a/esphome/components/water_heater/water_heater.h b/esphome/components/water_heater/water_heater.h
index 070ae99575..a1e1ca10a6 100644
--- a/esphome/components/water_heater/water_heater.h
+++ b/esphome/components/water_heater/water_heater.h
@@ -76,7 +76,8 @@ class WaterHeaterCall {
 
   WaterHeaterCall &set_mode(WaterHeaterMode mode);
   WaterHeaterCall &set_mode(const char *mode);
-  WaterHeaterCall &set_mode(const std::string &mode) { return this->set_mode(mode.c_str()); }
+  WaterHeaterCall &set_mode(const char *mode, size_t len);
+  WaterHeaterCall &set_mode(const std::string &mode) { return this->set_mode(mode.c_str(), mode.size()); }
   WaterHeaterCall &set_target_temperature(float temperature);
   WaterHeaterCall &set_target_temperature_low(float temperature);
   WaterHeaterCall &set_target_temperature_high(float temperature);
diff --git a/esphome/components/web_server/web_server.cpp b/esphome/components/web_server/web_server.cpp
index 4824e33dcd..47e427c0d1 100644
--- a/esphome/components/web_server/web_server.cpp
+++ b/esphome/components/web_server/web_server.cpp
@@ -969,7 +969,9 @@ void WebServer::handle_light_request(AsyncWebServerRequest *request, const UrlMa
       parse_light_param_uint_(request, ESPHOME_F("transition"), call, &decltype(call)::set_transition_length, 1000);
 
       if (is_on) {
-        parse_string_param_(request, ESPHOME_F("effect"), call, &decltype(call)::set_effect);
+        parse_cstr_param_(
+            request, ESPHOME_F("effect"), call,
+            static_cast<light::LightCall &(light::LightCall::*) (const char *, size_t)>(&decltype(call)::set_effect));
       }
 
       DEFER_ACTION(call, call.perform());
@@ -1368,7 +1370,9 @@ void WebServer::handle_text_request(AsyncWebServerRequest *request, const UrlMat
     }
 
     auto call = obj->make_call();
-    parse_string_param_(request, ESPHOME_F("value"), call, &decltype(call)::set_value);
+    parse_cstr_param_(
+        request, ESPHOME_F("value"), call,
+        static_cast<text::TextCall &(text::TextCall::*) (const char *, size_t)>(&decltype(call)::set_value));
 
     DEFER_ACTION(call, call.perform());
     request->send(200);
@@ -1426,7 +1430,9 @@ void WebServer::handle_select_request(AsyncWebServerRequest *request, const UrlM
     }
 
     auto call = obj->make_call();
-    parse_string_param_(request, ESPHOME_F("option"), call, &decltype(call)::set_option);
+    parse_cstr_param_(
+        request, ESPHOME_F("option"), call,
+        static_cast<select::SelectCall &(select::SelectCall::*) (const char *, size_t)>(&decltype(call)::set_option));
 
     DEFER_ACTION(call, call.perform());
     request->send(200);
@@ -1487,10 +1493,18 @@ void WebServer::handle_climate_request(AsyncWebServerRequest *request, const Url
     auto call = obj->make_call();
 
     // Parse string mode parameters
-    parse_string_param_(request, ESPHOME_F("mode"), call, &decltype(call)::set_mode);
-    parse_string_param_(request, ESPHOME_F("fan_mode"), call, &decltype(call)::set_fan_mode);
-    parse_string_param_(request, ESPHOME_F("swing_mode"), call, &decltype(call)::set_swing_mode);
-    parse_string_param_(request, ESPHOME_F("preset"), call, &decltype(call)::set_preset);
+    parse_cstr_param_(
+        request, ESPHOME_F("mode"), call,
+        static_cast<climate::ClimateCall &(climate::ClimateCall::*) (const char *, size_t)>(&decltype(call)::set_mode));
+    parse_cstr_param_(request, ESPHOME_F("fan_mode"), call,
+                      static_cast<climate::ClimateCall &(climate::ClimateCall::*) (const char *, size_t)>(
+                          &decltype(call)::set_fan_mode));
+    parse_cstr_param_(request, ESPHOME_F("swing_mode"), call,
+                      static_cast<climate::ClimateCall &(climate::ClimateCall::*) (const char *, size_t)>(
+                          &decltype(call)::set_swing_mode));
+    parse_cstr_param_(request, ESPHOME_F("preset"), call,
+                      static_cast<climate::ClimateCall &(climate::ClimateCall::*) (const char *, size_t)>(
+                          &decltype(call)::set_preset));
 
     // Parse temperature parameters
     // static_cast needed to disambiguate overloaded setters (float vs optional<float>)
@@ -1804,7 +1818,10 @@ void WebServer::handle_alarm_control_panel_request(AsyncWebServerRequest *reques
     }
 
     auto call = obj->make_call();
-    parse_string_param_(request, ESPHOME_F("code"), call, &decltype(call)::set_code);
+    parse_cstr_param_(
+        request, ESPHOME_F("code"), call,
+        static_cast<alarm_control_panel::AlarmControlPanelCall &(
+            alarm_control_panel::AlarmControlPanelCall::*) (const char *, size_t)>(&decltype(call)::set_code));
 
     // Lookup table for alarm control panel methods
     static const struct {
@@ -1892,7 +1909,10 @@ void WebServer::handle_water_heater_request(AsyncWebServerRequest *request, cons
     water_heater::WaterHeaterCall &base_call = call;
 
     // Parse mode parameter
-    parse_string_param_(request, ESPHOME_F("mode"), base_call, &water_heater::WaterHeaterCall::set_mode);
+    parse_cstr_param_(
+        request, ESPHOME_F("mode"), base_call,
+        static_cast<water_heater::WaterHeaterCall &(water_heater::WaterHeaterCall::*) (const char *, size_t)>(
+            &water_heater::WaterHeaterCall::set_mode));
 
     // Parse temperature parameters
     parse_num_param_(request, ESPHOME_F("target_temperature"), base_call,
diff --git a/esphome/components/web_server/web_server.h b/esphome/components/web_server/web_server.h
index 64c492f82b..6152dfbfd3 100644
--- a/esphome/components/web_server/web_server.h
+++ b/esphome/components/web_server/web_server.h
@@ -533,13 +533,13 @@ class WebServer final : public Controller, public Component, public AsyncWebHand
     }
   }
 
-  // Generic helper to parse and apply a string parameter
+  // Generic helper to parse and apply a string parameter using const char* setter (avoids std::string allocation)
   template<typename T, typename Ret>
-  void parse_string_param_(AsyncWebServerRequest *request, ParamNameType param_name, T &call,
-                           Ret (T::*setter)(const std::string &)) {
+  void parse_cstr_param_(AsyncWebServerRequest *request, ParamNameType param_name, T &call,
+                         Ret (T::*setter)(const char *, size_t)) {
     if (request->hasArg(param_name)) {
       const auto &value = request->arg(param_name);
-      (call.*setter)(std::string(value.c_str(), value.length()));
+      (call.*setter)(value.c_str(), value.length());
     }
   }
 
diff --git a/esphome/components/wifi/wifi_component.cpp b/esphome/components/wifi/wifi_component.cpp
index 1e6961b8bd..7d5d0133c1 100644
--- a/esphome/components/wifi/wifi_component.cpp
+++ b/esphome/components/wifi/wifi_component.cpp
@@ -2121,7 +2121,7 @@ bool WiFiComponent::can_proceed() {
 #endif
 
 void WiFiComponent::set_reboot_timeout(uint32_t reboot_timeout) { this->reboot_timeout_ = reboot_timeout; }
-bool WiFiComponent::is_connected() {
+bool WiFiComponent::is_connected() const {
   return this->state_ == WIFI_COMPONENT_STATE_STA_CONNECTED &&
          this->wifi_sta_connect_status_() == WiFiSTAConnectStatus::CONNECTED && !this->error_from_callback_;
 }
diff --git a/esphome/components/wifi/wifi_component.h b/esphome/components/wifi/wifi_component.h
index 63c7039f21..a6f03a08d9 100644
--- a/esphome/components/wifi/wifi_component.h
+++ b/esphome/components/wifi/wifi_component.h
@@ -443,7 +443,7 @@ class WiFiComponent : public Component {
 
   void set_reboot_timeout(uint32_t reboot_timeout);
 
-  bool is_connected();
+  bool is_connected() const;
 
   void set_power_save_mode(WiFiPowerSaveMode power_save);
   void set_min_auth_mode(WifiMinAuthMode min_auth_mode) { min_auth_mode_ = min_auth_mode; }
@@ -677,7 +677,7 @@ class WiFiComponent : public Component {
   bool wifi_apply_hostname_();
   bool wifi_sta_connect_(const WiFiAP &ap);
   void wifi_pre_setup_();
-  WiFiSTAConnectStatus wifi_sta_connect_status_();
+  WiFiSTAConnectStatus wifi_sta_connect_status_() const;
   bool wifi_scan_start_(bool passive);
 
 #ifdef USE_WIFI_AP
diff --git a/esphome/components/wifi/wifi_component_esp8266.cpp b/esphome/components/wifi/wifi_component_esp8266.cpp
index 8911bf15e0..bd6a18a99b 100644
--- a/esphome/components/wifi/wifi_component_esp8266.cpp
+++ b/esphome/components/wifi/wifi_component_esp8266.cpp
@@ -622,7 +622,7 @@ void WiFiComponent::wifi_pre_setup_() {
   this->wifi_mode_(false, false);
 }
 
-WiFiSTAConnectStatus WiFiComponent::wifi_sta_connect_status_() {
+WiFiSTAConnectStatus WiFiComponent::wifi_sta_connect_status_() const {
   station_status_t status = wifi_station_get_connect_status();
   if (status == STATION_GOT_IP)
     return WiFiSTAConnectStatus::CONNECTED;
diff --git a/esphome/components/wifi/wifi_component_esp_idf.cpp b/esphome/components/wifi/wifi_component_esp_idf.cpp
index 57bbceb1b8..734d186205 100644
--- a/esphome/components/wifi/wifi_component_esp_idf.cpp
+++ b/esphome/components/wifi/wifi_component_esp_idf.cpp
@@ -921,7 +921,7 @@ void WiFiComponent::wifi_process_event_(IDFWiFiEvent *data) {
   }
 }
 
-WiFiSTAConnectStatus WiFiComponent::wifi_sta_connect_status_() {
+WiFiSTAConnectStatus WiFiComponent::wifi_sta_connect_status_() const {
   if (s_sta_connected && this->got_ipv4_address_) {
 #if USE_NETWORK_IPV6 && (USE_NETWORK_MIN_IPV6_ADDR_COUNT > 0)
     if (this->num_ipv6_addresses_ >= USE_NETWORK_MIN_IPV6_ADDR_COUNT) {
diff --git a/esphome/components/wifi/wifi_component_libretiny.cpp b/esphome/components/wifi/wifi_component_libretiny.cpp
index 1c5490a3ac..4c4150e44d 100644
--- a/esphome/components/wifi/wifi_component_libretiny.cpp
+++ b/esphome/components/wifi/wifi_component_libretiny.cpp
@@ -634,7 +634,7 @@ void WiFiComponent::wifi_pre_setup_() {
   // Make sure WiFi is in clean state before anything starts
   this->wifi_mode_(false, false);
 }
-WiFiSTAConnectStatus WiFiComponent::wifi_sta_connect_status_() {
+WiFiSTAConnectStatus WiFiComponent::wifi_sta_connect_status_() const {
   // Use state machine instead of querying WiFi.status() directly
   // State is updated in main loop from queued events, ensuring thread safety
   switch (s_sta_state) {
diff --git a/esphome/components/wifi/wifi_component_pico_w.cpp b/esphome/components/wifi/wifi_component_pico_w.cpp
index 9b2c077dc5..270425d8c2 100644
--- a/esphome/components/wifi/wifi_component_pico_w.cpp
+++ b/esphome/components/wifi/wifi_component_pico_w.cpp
@@ -120,7 +120,7 @@ const char *get_disconnect_reason_str(uint8_t reason) {
   return "UNKNOWN";
 }
 
-WiFiSTAConnectStatus WiFiComponent::wifi_sta_connect_status_() {
+WiFiSTAConnectStatus WiFiComponent::wifi_sta_connect_status_() const {
   // Use cyw43_wifi_link_status instead of cyw43_tcpip_link_status because the Arduino
   // framework's __wrap_cyw43_cb_tcpip_init is a no-op — the SDK's internal netif
   // (cyw43_state.netif[]) is never initialized. cyw43_tcpip_link_status checks that netif's
diff --git a/esphome/components/zephyr/__init__.py b/esphome/components/zephyr/__init__.py
index 43d5cebebb..4cc71bddca 100644
--- a/esphome/components/zephyr/__init__.py
+++ b/esphome/components/zephyr/__init__.py
@@ -112,6 +112,7 @@ def add_extra_script(stage: str, filename: str, path: Path) -> None:
 
 def zephyr_to_code(config):
     cg.add_build_flag("-DUSE_ZEPHYR")
+    cg.add_define("USE_NATIVE_64BIT_TIME")
     cg.set_cpp_standard("gnu++20")
     # build is done by west so bypass board checking in platformio
     cg.add_platformio_option("boards_dir", CORE.relative_build_path("boards"))
diff --git a/esphome/components/zephyr/core.cpp b/esphome/components/zephyr/core.cpp
index f0772a4422..cf3ea70245 100644
--- a/esphome/components/zephyr/core.cpp
+++ b/esphome/components/zephyr/core.cpp
@@ -60,6 +60,7 @@ void arch_restart() { sys_reboot(SYS_REBOOT_COLD); }
 uint32_t arch_get_cpu_cycle_count() { return k_cycle_get_32(); }
 uint32_t arch_get_cpu_freq_hz() { return sys_clock_hw_cycles_per_sec(); }
 uint8_t progmem_read_byte(const uint8_t *addr) { return *addr; }
+uint16_t progmem_read_uint16(const uint16_t *addr) { return *addr; }
 
 Mutex::Mutex() {
   auto *mutex = new k_mutex();
diff --git a/esphome/core/application.cpp b/esphome/core/application.cpp
index 3c3d69ff16..8c2ba58c86 100644
--- a/esphome/core/application.cpp
+++ b/esphome/core/application.cpp
@@ -79,7 +79,12 @@ static void insertion_sort_by_priority(Iterator first, Iterator last) {
   }
 }
 
-void Application::register_component_(Component *comp) { this->components_.push_back(comp); }
+void Application::register_component_impl_(Component *comp, bool has_loop) {
+  if (has_loop) {
+    comp->component_state_ |= COMPONENT_HAS_LOOP;
+  }
+  this->components_.push_back(comp);
+}
 void Application::setup() {
   ESP_LOGI(TAG, "Running through setup()");
   ESP_LOGV(TAG, "Sorting components by setup priority");
@@ -382,16 +387,8 @@ void Application::teardown_components(uint32_t timeout_ms) {
 }
 
 void Application::calculate_looping_components_() {
-  // Count total components that need looping
-  size_t total_looping = 0;
-  for (auto *obj : this->components_) {
-    if (obj->has_overridden_loop()) {
-      total_looping++;
-    }
-  }
-
-  // Initialize FixedVector with exact size - no reallocation possible
-  this->looping_components_.init(total_looping);
+  // FixedVector capacity was pre-initialized by codegen with the exact count
+  // of components that override loop(), computed at C++ compile time.
 
   // Add all components with loop override that aren't already LOOP_DONE
   // Some components (like logger) may call disable_loop() during initialization
diff --git a/esphome/core/application.h b/esphome/core/application.h
index c760f64e3f..f2b874cff1 100644
--- a/esphome/core/application.h
+++ b/esphome/core/application.h
@@ -5,6 +5,7 @@
 #include <limits>
 #include <span>
 #include <string>
+#include <type_traits>
 #include <vector>
 #include "esphome/core/component.h"
 #include "esphome/core/defines.h"
@@ -510,7 +511,7 @@ class Application {
   void wake_loop_threadsafe();
 #endif
 
-#if defined(USE_WAKE_LOOP_THREADSAFE) && defined(USE_LWIP_FAST_SELECT)
+#ifdef USE_LWIP_FAST_SELECT
   /// Wake the main event loop from an ISR.
   /// Uses vTaskNotifyGiveFromISR() — <1 us, ISR-safe.
   /// Only available on platforms with fast select (ESP32, LibreTiny).
@@ -518,6 +519,12 @@ class Application {
   static void IRAM_ATTR wake_loop_isrsafe(int *px_higher_priority_task_woken) {
     esphome_lwip_wake_main_loop_from_isr(px_higher_priority_task_woken);
   }
+
+#ifdef USE_ESP32
+  /// Wake the main event loop from any context (ISR, thread, or main loop).
+  /// Detects the calling context and uses the appropriate FreeRTOS API.
+  static void IRAM_ATTR wake_loop_any_context() { esphome_lwip_wake_main_loop_any_context(); }
+#endif
 #endif
 
  protected:
@@ -532,7 +539,14 @@ class Application {
   bool is_socket_ready_(int fd) const { return FD_ISSET(fd, &this->read_fds_); }
 #endif
 
-  void register_component_(Component *comp);
+  /// Register a component, detecting loop() override at compile time.
+  /// The template resolves &T::loop vs &Component::loop as a constexpr bool
+  /// and forwards it to register_component_impl_ which stores it in component_state_.
+  template<typename T> void register_component_(T *comp) {
+    this->register_component_impl_(comp, !std::is_same_v<decltype(&T::loop), decltype(&Component::loop)>);
+  }
+
+  void register_component_impl_(Component *comp, bool has_loop);
 
   void calculate_looping_components_();
   void add_looping_components_by_state_(bool match_loop_done);
diff --git a/esphome/core/automation.h b/esphome/core/automation.h
index 31a2fc06f4..7934fdbec9 100644
--- a/esphome/core/automation.h
+++ b/esphome/core/automation.h
@@ -4,6 +4,7 @@
 #include "esphome/core/defines.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/preferences.h"
+#include "esphome/core/progmem.h"
 #include "esphome/core/string_ref.h"
 #include <concepts>
 #include <functional>
@@ -56,6 +57,16 @@ template<typename T, typename... X> class TemplatableValue {
     this->static_str_ = str;
   }
 
+#ifdef USE_ESP8266
+  // On ESP8266, __FlashStringHelper* is a distinct type from const char*.
+  // ESPHOME_F(s) expands to F(s) which returns __FlashStringHelper* pointing to PROGMEM.
+  // Store as FLASH_STRING — value()/is_empty()/ref_or_copy_to() use _P functions
+  // to access the PROGMEM pointer safely.
+  TemplatableValue(const __FlashStringHelper *str) requires std::same_as<T, std::string> : type_(FLASH_STRING) {
+    this->static_str_ = reinterpret_cast<const char *>(str);
+  }
+#endif
+
   template<typename F> TemplatableValue(F value) requires(!std::invocable<F, X...>) : type_(VALUE) {
     if constexpr (USE_HEAP_STORAGE) {
       this->value_ = new T(std::move(value));
@@ -89,7 +100,7 @@ template<typename T, typename... X> class TemplatableValue {
       this->f_ = new std::function<T(X...)>(*other.f_);
     } else if (this->type_ == STATELESS_LAMBDA) {
       this->stateless_f_ = other.stateless_f_;
-    } else if (this->type_ == STATIC_STRING) {
+    } else if (this->type_ == STATIC_STRING || this->type_ == FLASH_STRING) {
       this->static_str_ = other.static_str_;
     }
   }
@@ -108,7 +119,7 @@ template<typename T, typename... X> class TemplatableValue {
       other.f_ = nullptr;
     } else if (this->type_ == STATELESS_LAMBDA) {
       this->stateless_f_ = other.stateless_f_;
-    } else if (this->type_ == STATIC_STRING) {
+    } else if (this->type_ == STATIC_STRING || this->type_ == FLASH_STRING) {
       this->static_str_ = other.static_str_;
     }
     other.type_ = NONE;
@@ -141,7 +152,7 @@ template<typename T, typename... X> class TemplatableValue {
     } else if (this->type_ == LAMBDA) {
       delete this->f_;
     }
-    // STATELESS_LAMBDA/STATIC_STRING/NONE: no cleanup needed (pointers, not heap-allocated)
+    // STATELESS_LAMBDA/STATIC_STRING/FLASH_STRING/NONE: no cleanup needed (pointers, not heap-allocated)
   }
 
   bool has_value() const { return this->type_ != NONE; }
@@ -165,6 +176,17 @@ template<typename T, typename... X> class TemplatableValue {
           return std::string(this->static_str_);
         }
         __builtin_unreachable();
+#ifdef USE_ESP8266
+      case FLASH_STRING:
+        // PROGMEM pointer — must use _P functions to access on ESP8266
+        if constexpr (std::same_as<T, std::string>) {
+          size_t len = strlen_P(this->static_str_);
+          std::string result(len, '\0');
+          memcpy_P(result.data(), this->static_str_, len);
+          return result;
+        }
+        __builtin_unreachable();
+#endif
       case NONE:
       default:
         return T{};
@@ -186,9 +208,12 @@ template<typename T, typename... X> class TemplatableValue {
   }
 
   /// Check if this holds a static string (const char* stored without allocation)
+  /// The pointer is always directly readable (RAM or flash-mapped).
+  /// Returns false for FLASH_STRING (PROGMEM on ESP8266, requires _P functions).
   bool is_static_string() const { return this->type_ == STATIC_STRING; }
 
   /// Get the static string pointer (only valid if is_static_string() returns true)
+  /// The pointer is always directly readable — FLASH_STRING uses a separate type.
   const char *get_static_string() const { return this->static_str_; }
 
   /// Check if the string value is empty without allocating (for std::string specialization).
@@ -200,6 +225,12 @@ template<typename T, typename... X> class TemplatableValue {
         return true;
       case STATIC_STRING:
         return this->static_str_ == nullptr || this->static_str_[0] == '\0';
+#ifdef USE_ESP8266
+      case FLASH_STRING:
+        // PROGMEM pointer — must use progmem_read_byte on ESP8266
+        return this->static_str_ == nullptr ||
+               progmem_read_byte(reinterpret_cast<const uint8_t *>(this->static_str_)) == '\0';
+#endif
       case VALUE:
         return this->value_->empty();
       default:  // LAMBDA/STATELESS_LAMBDA - must call value()
@@ -209,8 +240,9 @@ template<typename T, typename... X> class TemplatableValue {
 
   /// Get a StringRef to the string value without heap allocation when possible.
   /// For STATIC_STRING/VALUE, returns reference to existing data (no allocation).
+  /// For FLASH_STRING (ESP8266 PROGMEM), copies to provided buffer via _P functions.
   /// For LAMBDA/STATELESS_LAMBDA, calls value(), copies to provided buffer, returns ref to buffer.
-  /// @param lambda_buf Buffer used only for lambda case (must remain valid while StringRef is used).
+  /// @param lambda_buf Buffer used only for copy cases (must remain valid while StringRef is used).
   /// @param lambda_buf_size Size of the buffer.
   /// @return StringRef pointing to the string data.
   StringRef ref_or_copy_to(char *lambda_buf, size_t lambda_buf_size) const requires std::same_as<T, std::string> {
@@ -221,6 +253,19 @@ template<typename T, typename... X> class TemplatableValue {
         if (this->static_str_ == nullptr)
           return StringRef();
         return StringRef(this->static_str_, strlen(this->static_str_));
+#ifdef USE_ESP8266
+      case FLASH_STRING:
+        if (this->static_str_ == nullptr)
+          return StringRef();
+        {
+          // PROGMEM pointer — copy to buffer via _P functions
+          size_t len = strlen_P(this->static_str_);
+          size_t copy_len = std::min(len, lambda_buf_size - 1);
+          memcpy_P(lambda_buf, this->static_str_, copy_len);
+          lambda_buf[copy_len] = '\0';
+          return StringRef(lambda_buf, copy_len);
+        }
+#endif
       case VALUE:
         return StringRef(this->value_->data(), this->value_->size());
       default: {  // LAMBDA/STATELESS_LAMBDA - must call value() and copy
@@ -239,6 +284,7 @@ template<typename T, typename... X> class TemplatableValue {
    LAMBDA,
    STATELESS_LAMBDA,
    STATIC_STRING,  // For const char* when T is std::string - avoids heap allocation
+   FLASH_STRING,   // PROGMEM pointer on ESP8266; never set on other platforms
  } type_;
   // For std::string, use heap pointer to minimize union size (4 bytes vs 12+).
   // For other types, store value inline as before.
@@ -247,7 +293,7 @@ template<typename T, typename... X> class TemplatableValue {
     ValueStorage value_;  // T for inline storage, T* for heap storage
     std::function<T(X...)> *f_;
     T (*stateless_f_)(X...);
-    const char *static_str_;  // For STATIC_STRING type
+    const char *static_str_;  // For STATIC_STRING and FLASH_STRING types
   };
 };
 
diff --git a/esphome/core/component.cpp b/esphome/core/component.cpp
index fd4e0d2984..a71aa8b3a3 100644
--- a/esphome/core/component.cpp
+++ b/esphome/core/component.cpp
@@ -315,7 +315,7 @@ void IRAM_ATTR HOT Component::enable_loop_soon_any_context() {
   // This method is thread and ISR-safe because:
   // 1. Only performs simple assignments to volatile variables (atomic on all platforms)
   // 2. No read-modify-write operations that could be interrupted
-  // 3. No memory allocation, object construction, or function calls
+  // 3. No memory allocation or object construction; on ESP32 the only call (wake_loop_any_context) is ISR-safe
   // 4. IRAM_ATTR ensures code is in IRAM, not flash (required for ISR execution)
   // 5. Components are never destroyed, so no use-after-free concerns
   // 6. App is guaranteed to be initialized before any ISR could fire
@@ -323,6 +323,12 @@ void IRAM_ATTR HOT Component::enable_loop_soon_any_context() {
   // 8. Race condition with main loop is handled by clearing flag before processing
   this->pending_enable_loop_ = true;
   App.has_pending_enable_loop_requests_ = true;
+#if defined(USE_LWIP_FAST_SELECT) && defined(USE_ESP32)
+  // Wake the main loop if sleeping in ulTaskNotifyTake(). Without this,
+  // the main loop would not wake until the select timeout expires (~16ms).
+  // Uses xPortInIsrContext() to choose the correct FreeRTOS notify API.
+  Application::wake_loop_any_context();
+#endif
 }
 void Component::reset_to_construction_state() {
   if ((this->component_state_ & COMPONENT_STATE_MASK) == COMPONENT_STATE_FAILED) {
@@ -490,18 +496,6 @@ void Component::set_setup_priority(float priority) {
 }
 #endif
 
-bool Component::has_overridden_loop() const {
-#if defined(USE_HOST) || defined(CLANG_TIDY)
-  return true;
-#else
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpmf-conversions"
-  bool loop_overridden = (void *) (this->*(&Component::loop)) != (void *) (&Component::loop);
-#pragma GCC diagnostic pop
-  return loop_overridden;
-#endif
-}
-
 PollingComponent::PollingComponent(uint32_t update_interval) : update_interval_(update_interval) {}
 
 void PollingComponent::call_setup() {
diff --git a/esphome/core/component.h b/esphome/core/component.h
index 6b920da290..d8102ea670 100644
--- a/esphome/core/component.h
+++ b/esphome/core/component.h
@@ -76,6 +76,8 @@ inline constexpr uint8_t STATUS_LED_MASK = 0x18;
 inline constexpr uint8_t STATUS_LED_OK = 0x00;
 inline constexpr uint8_t STATUS_LED_WARNING = 0x08;
 inline constexpr uint8_t STATUS_LED_ERROR = 0x10;
+// Component loop override flag uses bit 5 (set at registration time)
+inline constexpr uint8_t COMPONENT_HAS_LOOP = 0x20;
 
 // Remove before 2026.8.0
 enum class RetryResult { DONE, RETRY };
@@ -271,7 +273,7 @@ class Component {
    */
   void status_momentary_error(const char *name, uint32_t length = 5000);
 
-  bool has_overridden_loop() const;
+  bool has_overridden_loop() const { return (this->component_state_ & COMPONENT_HAS_LOOP) != 0; }
 
   /** Set where this component was loaded from for some debug messages.
    *
@@ -510,7 +512,8 @@ class Component {
   /// Bits 0-2: Component state (0x00=CONSTRUCTION, 0x01=SETUP, 0x02=LOOP, 0x03=FAILED, 0x04=LOOP_DONE)
   /// Bit 3: STATUS_LED_WARNING
   /// Bit 4: STATUS_LED_ERROR
-  /// Bits 5-7: Unused - reserved for future expansion
+  /// Bit 5: Has overridden loop() (set at registration time)
+  /// Bits 6-7: Unused - reserved for future expansion
   uint8_t component_state_{0x00};
   volatile bool pending_enable_loop_{false};  ///< ISR-safe flag for enable_loop_soon_any_context
 };
diff --git a/esphome/core/config.py b/esphome/core/config.py
index 215432835a..3835fd3875 100644
--- a/esphome/core/config.py
+++ b/esphome/core/config.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from collections import Counter
 import logging
 import os
 from pathlib import Path
@@ -504,6 +505,40 @@ async def _add_controller_registry_define() -> None:
         cg.add_define("CONTROLLER_REGISTRY_MAX", controller_count)
 
 
+@coroutine_with_priority(CoroPriority.FINAL)
+async def _add_looping_components() -> None:
+    # Emit a constexpr that computes the looping component count at C++ compile time
+    # and pre-init the FixedVector with the exact capacity. Uses std::is_same_v to
+    # detect loop() overrides. The constexpr goes in main.cpp's global section where
+    # all component types are in scope. calculate_looping_components_() then skips
+    # the counting pass and only does the two population passes.
+    entries = CORE.data.get("looping_component_entries", [])
+    if not entries:
+        return
+
+    # Build constexpr sum for the exact count, deduplicating by type
+    type_counts = Counter(entries)
+    terms = [
+        f"({count} * !std::is_same_v<decltype(&{cpp_type}::loop), decltype(&Component::loop)>)"
+        for cpp_type, count in type_counts.items()
+    ]
+    constexpr_expr = " + \\\n  ".join(terms)
+    cg.add_global(
+        cg.RawStatement(
+            f"static constexpr size_t ESPHOME_LOOPING_COMPONENT_COUNT = \\\n"
+            f"  {constexpr_expr};"
+        )
+    )
+
+    # Pre-init FixedVector with exact capacity so calculate_looping_components_()
+    # can skip the counting pass
+    cg.add(
+        cg.RawExpression(
+            "App.looping_components_.init(ESPHOME_LOOPING_COMPONENT_COUNT)"
+        )
+    )
+
+
 @coroutine_with_priority(CoroPriority.CORE)
 async def to_code(config: ConfigType) -> None:
     cg.add_global(cg.global_ns.namespace("esphome").using)
@@ -527,6 +562,7 @@ async def to_code(config: ConfigType) -> None:
 
     CORE.add_job(_add_platform_defines)
     CORE.add_job(_add_controller_registry_define)
+    CORE.add_job(_add_looping_components)
 
     CORE.add_job(_add_automations, config)
 
@@ -650,6 +686,12 @@ FILTER_SOURCE_FILES = filter_source_files_from_platform(
             PlatformFramework.ESP32_ARDUINO,
             PlatformFramework.ESP32_IDF,
         },
+        "time_64.cpp": {
+            PlatformFramework.ESP8266_ARDUINO,
+            PlatformFramework.BK72XX_ARDUINO,
+            PlatformFramework.RTL87XX_ARDUINO,
+            PlatformFramework.LN882X_ARDUINO,
+        },
         # Note: lock_free_queue.h and event_pool.h are header files and don't need to be filtered
         # as they are only included when needed by the preprocessor
     }
diff --git a/esphome/core/controller_registry.cpp b/esphome/core/controller_registry.cpp
index 13b505e8e9..255efa86ba 100644
--- a/esphome/core/controller_registry.cpp
+++ b/esphome/core/controller_registry.cpp
@@ -10,21 +10,26 @@ StaticVector<Controller *, CONTROLLER_REGISTRY_MAX> ControllerRegistry::controll
 
 void ControllerRegistry::register_controller(Controller *controller) { controllers.push_back(controller); }
 
+void ControllerRegistry::notify(void *obj, DispatchFunc dispatch) {
+  for (auto *controller : controllers) {
+    dispatch(controller, obj);
+  }
+}
+
 // Macro for standard registry notification dispatch - calls on_<entity_name>_update()
+// Each wrapper passes a small trampoline lambda that calls the correct virtual method.
+// NOLINTBEGIN(bugprone-macro-parentheses)
 #define CONTROLLER_REGISTRY_NOTIFY(entity_type, entity_name) \
-  void ControllerRegistry::notify_##entity_name##_update(entity_type *obj) { /* NOLINT(bugprone-macro-parentheses) */ \
-    for (auto *controller : controllers) { \
-      controller->on_##entity_name##_update(obj); \
-    } \
+  void ControllerRegistry::notify_##entity_name##_update(entity_type *obj) { \
+    notify(obj, [](Controller *c, void *o) { c->on_##entity_name##_update(static_cast<entity_type *>(o)); }); \
   }
 
 // Macro for entities where controller method has no "_update" suffix (Event, Update)
 #define CONTROLLER_REGISTRY_NOTIFY_NO_UPDATE_SUFFIX(entity_type, entity_name) \
-  void ControllerRegistry::notify_##entity_name(entity_type *obj) { /* NOLINT(bugprone-macro-parentheses) */ \
-    for (auto *controller : controllers) { \
-      controller->on_##entity_name(obj); \
-    } \
+  void ControllerRegistry::notify_##entity_name(entity_type *obj) { \
+    notify(obj, [](Controller *c, void *o) { c->on_##entity_name(static_cast<entity_type *>(o)); }); \
   }
+// NOLINTEND(bugprone-macro-parentheses)
 
 #ifdef USE_BINARY_SENSOR
 CONTROLLER_REGISTRY_NOTIFY(binary_sensor::BinarySensor, binary_sensor)
diff --git a/esphome/core/controller_registry.h b/esphome/core/controller_registry.h
index d6452d8827..15e3b4ba83 100644
--- a/esphome/core/controller_registry.h
+++ b/esphome/core/controller_registry.h
@@ -247,6 +247,21 @@ class ControllerRegistry {
 #endif
 
  protected:
+  /** Type-erased dispatch function pointer.
+   *
+   * Each notify method passes a small trampoline that calls the
+   * correct virtual method on Controller. The shared notify() loop
+   * iterates controllers once, calling the trampoline for each.
+   */
+  using DispatchFunc = void (*)(Controller *, void *);
+
+  /** Shared dispatch loop - iterates controllers and calls dispatch for each.
+   *
+   * Marked noinline to ensure only one copy of the loop exists in flash,
+   * rather than being duplicated into each notify_*_update wrapper.
+   */
+  static void __attribute__((noinline)) notify(void *obj, DispatchFunc dispatch);
+
   static StaticVector<Controller *, CONTROLLER_REGISTRY_MAX> controllers;
 };
 
diff --git a/esphome/core/defines.h b/esphome/core/defines.h
index 5c982c94b1..8c78afa7d4 100644
--- a/esphome/core/defines.h
+++ b/esphome/core/defines.h
@@ -55,11 +55,13 @@
 #define USE_HOMEASSISTANT_TIME
 #define USE_HTTP_REQUEST_OTA_WATCHDOG_TIMEOUT 8000  // NOLINT
 #define USE_IMAGE
+#define USE_IMPROV_SERIAL
 #define USE_IMPROV_SERIAL_NEXT_URL
 #define USE_INFRARED
 #define USE_IR_RF
 #define USE_JSON
 #define USE_LIGHT
+#define USE_LIGHT_GAMMA_LUT
 #define USE_LOCK
 #define USE_LOGGER
 #define USE_LOGGER_LEVEL_LISTENERS
@@ -177,6 +179,11 @@
 #define USE_I2S_LEGACY
 #endif
 
+// Platforms with native 64-bit time sources (no rollover tracking needed)
+#if defined(USE_ESP32) || defined(USE_HOST) || defined(USE_ZEPHYR) || defined(USE_RP2040)
+#define USE_NATIVE_64BIT_TIME
+#endif
+
 // ESP32-specific feature flags
 #ifdef USE_ESP32
 #define USE_MQTT_IDF_ENQUEUE
diff --git a/esphome/core/hal.h b/esphome/core/hal.h
index fa5ca646f2..ef45be629d 100644
--- a/esphome/core/hal.h
+++ b/esphome/core/hal.h
@@ -42,5 +42,6 @@ void arch_feed_wdt();
 uint32_t arch_get_cpu_cycle_count();
 uint32_t arch_get_cpu_freq_hz();
 uint8_t progmem_read_byte(const uint8_t *addr);
+uint16_t progmem_read_uint16(const uint16_t *addr);
 
 }  // namespace esphome
diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index b606e68df3..c68cb549bb 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -133,6 +133,78 @@ template<typename T> class ConstVector {
   size_t size_;
 };
 
+/// Small buffer optimization - stores data inline when small, heap-allocates for large data
+/// This avoids heap fragmentation for common small allocations while supporting arbitrary sizes.
+/// Memory management is encapsulated - callers just use set() and data().
+template<size_t InlineSize = 8> class SmallInlineBuffer {
+ public:
+  SmallInlineBuffer() = default;
+  ~SmallInlineBuffer() {
+    if (!this->is_inline_())
+      delete[] this->heap_;
+  }
+
+  // Move constructor
+  SmallInlineBuffer(SmallInlineBuffer &&other) noexcept : len_(other.len_) {
+    if (other.is_inline_()) {
+      memcpy(this->inline_, other.inline_, this->len_);
+    } else {
+      this->heap_ = other.heap_;
+      other.heap_ = nullptr;
+    }
+    other.len_ = 0;
+  }
+
+  // Move assignment
+  SmallInlineBuffer &operator=(SmallInlineBuffer &&other) noexcept {
+    if (this != &other) {
+      if (!this->is_inline_())
+        delete[] this->heap_;
+      this->len_ = other.len_;
+      if (other.is_inline_()) {
+        memcpy(this->inline_, other.inline_, this->len_);
+      } else {
+        this->heap_ = other.heap_;
+        other.heap_ = nullptr;
+      }
+      other.len_ = 0;
+    }
+    return *this;
+  }
+
+  // Disable copy (would need deep copy of heap data)
+  SmallInlineBuffer(const SmallInlineBuffer &) = delete;
+  SmallInlineBuffer &operator=(const SmallInlineBuffer &) = delete;
+
+  /// Set buffer contents, allocating heap if needed
+  void set(const uint8_t *src, size_t size) {
+    // Free existing heap allocation if switching from heap to inline or different heap size
+    if (!this->is_inline_() && (size <= InlineSize || size != this->len_)) {
+      delete[] this->heap_;
+      this->heap_ = nullptr;  // Defensive: prevent use-after-free if logic changes
+    }
+    // Allocate new heap buffer if needed
+    if (size > InlineSize && (this->is_inline_() || size != this->len_)) {
+      this->heap_ = new uint8_t[size];  // NOLINT(cppcoreguidelines-owning-memory)
+    }
+    this->len_ = size;
+    memcpy(this->data(), src, size);
+  }
+
+  uint8_t *data() { return this->is_inline_() ? this->inline_ : this->heap_; }
+  const uint8_t *data() const { return this->is_inline_() ? this->inline_ : this->heap_; }
+  size_t size() const { return this->len_; }
+
+ protected:
+  bool is_inline_() const { return this->len_ <= InlineSize; }
+
+  size_t len_{0};
+  union {
+    uint8_t inline_[InlineSize]{};  // Zero-init ensures clean initial state
+    uint8_t *heap_;
+  };
+};
+
 /// Minimal static vector - saves memory by avoiding std::vector overhead
 template<typename T, size_t N> class StaticVector {
  public:
@@ -1365,8 +1437,12 @@ bool base64_decode_int32_vector(const std::string &base64, std::vector<int32_t>
 ///@{
 
 /// Applies gamma correction of \p gamma to \p value.
+// Remove before 2026.9.0
+ESPDEPRECATED("Use LightState::gamma_correct_lut() instead. Removed in 2026.9.0.", "2026.3.0")
 float gamma_correct(float value, float gamma);
 /// Reverts gamma correction of \p gamma to \p value.
+// Remove before 2026.9.0
+ESPDEPRECATED("Use LightState::gamma_uncorrect_lut() instead. Removed in 2026.9.0.", "2026.3.0")
 float gamma_uncorrect(float value, float gamma);
 
 /// Convert \p red, \p green and \p blue (all 0-1) values to \p hue (0-360), \p saturation (0-1) and \p value (0-1).
diff --git a/esphome/core/lwip_fast_select.c b/esphome/core/lwip_fast_select.c
index 83e1e0ee5c..c578a9aae9 100644
--- a/esphome/core/lwip_fast_select.c
+++ b/esphome/core/lwip_fast_select.c
@@ -105,10 +105,9 @@
 //     critical sections). Multiple concurrent xTaskNotifyGive calls are safe —
 //     the notification count simply increments.
 
-// USE_ESP32 and USE_LIBRETINY are compiler -D flags, so they are always visible in this .c file.
-// Feature macros like USE_LWIP_FAST_SELECT may come from generated headers that are not included here,
-// so this implementation is enabled based on platform flags instead of USE_LWIP_FAST_SELECT.
-#if defined(USE_ESP32) || defined(USE_LIBRETINY)
+// USE_LWIP_FAST_SELECT is set via -D build flag (not cg.add_define) so it is
+// visible in both .c and .cpp translation units.
+#ifdef USE_LWIP_FAST_SELECT
 
 // LwIP headers must come first — they define netconn_callback, struct lwip_sock, etc.
 #include <lwip/api.h>
@@ -233,4 +232,19 @@ void IRAM_ATTR esphome_lwip_wake_main_loop_from_isr(int *px_higher_priority_task
   }
 }
 
-#endif  // defined(USE_ESP32) || defined(USE_LIBRETINY)
+// Wake the main loop from any context (ISR, thread, or main loop).
+// ESP32-only: uses xPortInIsrContext() to detect ISR context.
+// LibreTiny is excluded because it lacks IRAM_ATTR support needed for ISR-safe paths.
+#ifdef USE_ESP32
+void IRAM_ATTR esphome_lwip_wake_main_loop_any_context(void) {
+  if (xPortInIsrContext()) {
+    int px_higher_priority_task_woken = 0;
+    esphome_lwip_wake_main_loop_from_isr(&px_higher_priority_task_woken);
+    portYIELD_FROM_ISR(px_higher_priority_task_woken);
+  } else {
+    esphome_lwip_wake_main_loop();
+  }
+}
+#endif
+
+#endif  // USE_LWIP_FAST_SELECT
diff --git a/esphome/core/lwip_fast_select.h b/esphome/core/lwip_fast_select.h
index fe6aa8ff92..46c6b711cd 100644
--- a/esphome/core/lwip_fast_select.h
+++ b/esphome/core/lwip_fast_select.h
@@ -66,6 +66,13 @@ void esphome_lwip_wake_main_loop(void);
 /// @param px_higher_priority_task_woken Set to pdTRUE if a context switch is needed.
 void esphome_lwip_wake_main_loop_from_isr(int *px_higher_priority_task_woken);
 
+/// Wake the main loop task from any context (ISR, thread, or main loop).
+/// ESP32-only: uses xPortInIsrContext() to detect ISR context.
+/// LibreTiny lacks IRAM_ATTR support needed for ISR-safe paths.
+#ifdef USE_ESP32
+void esphome_lwip_wake_main_loop_any_context(void);
+#endif
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/esphome/core/scheduler.cpp b/esphome/core/scheduler.cpp
index 2c10e7e2da..ca560e8250 100644
--- a/esphome/core/scheduler.cpp
+++ b/esphome/core/scheduler.cpp
@@ -9,7 +9,6 @@
 #include <algorithm>
 #include <cinttypes>
 #include <cstring>
-#include <limits>
 
 namespace esphome {
 
@@ -28,10 +27,6 @@ static constexpr size_t MAX_POOL_SIZE = 5;
 // Set to 5 to match the pool size - when we have as many cancelled items as our
 // pool can hold, it's time to clean up and recycle them.
 static constexpr uint32_t MAX_LOGICALLY_DELETED_ITEMS = 5;
-#if !defined(USE_ESP32) && !defined(USE_HOST) && !defined(USE_ZEPHYR) && !defined(USE_RP2040)
-// Half the 32-bit range - used to detect rollovers vs normal time progression
-static constexpr uint32_t HALF_MAX_UINT32 = std::numeric_limits<uint32_t>::max() / 2;
-#endif
 // max delay to start an interval sequence
 static constexpr uint32_t MAX_INTERVAL_DELAY = 5000;
 
@@ -152,9 +147,6 @@ void HOT Scheduler::set_timer_common_(Component *component, SchedulerItem::Type
     return;
   }
 
-  // Get fresh 64-bit timestamp BEFORE taking lock
-  const uint64_t now_64 = millis_64();
-
   // Take lock early to protect scheduler_item_pool_ access
   LockGuard guard{this->lock_};
 
@@ -181,6 +173,9 @@ void HOT Scheduler::set_timer_common_(Component *component, SchedulerItem::Type
   } else
 #endif /* not ESPHOME_THREAD_SINGLE */
   {
+    // Only non-defer items need a timestamp for scheduling
+    const uint64_t now_64 = millis_64();
+
     // Type-specific setup
     if (type == SchedulerItem::INTERVAL) {
       item->interval = delay;
@@ -475,19 +470,8 @@ void HOT Scheduler::call(uint32_t now) {
   if (now_64 - last_print > 2000) {
     last_print = now_64;
     std::vector<SchedulerItemPtr> old_items;
-#if !defined(USE_ESP32) && !defined(USE_HOST) && !defined(USE_ZEPHYR) && !defined(USE_RP2040) && \
-    defined(ESPHOME_THREAD_MULTI_ATOMICS)
-    const auto last_dbg = this->last_millis_.load(std::memory_order_relaxed);
-    const auto major_dbg = this->millis_major_.load(std::memory_order_relaxed);
-    ESP_LOGD(TAG, "Items: count=%zu, pool=%zu, now=%" PRIu64 " (%" PRIu16 ", %" PRIu32 ")", this->items_.size(),
-             this->scheduler_item_pool_.size(), now_64, major_dbg, last_dbg);
-#elif !defined(USE_ESP32) && !defined(USE_HOST) && !defined(USE_ZEPHYR) && !defined(USE_RP2040)
-    ESP_LOGD(TAG, "Items: count=%zu, pool=%zu, now=%" PRIu64 " (%" PRIu16 ", %" PRIu32 ")", this->items_.size(),
-             this->scheduler_item_pool_.size(), now_64, this->millis_major_, this->last_millis_);
-#else
     ESP_LOGD(TAG, "Items: count=%zu, pool=%zu, now=%" PRIu64, this->items_.size(), this->scheduler_item_pool_.size(),
              now_64);
-#endif
     // Cleanup before debug output
     this->cleanup_();
     while (!this->items_.empty()) {
@@ -715,166 +699,6 @@ bool HOT Scheduler::cancel_item_locked_(Component *component, NameType name_type
   return total_cancelled > 0;
 }
 
-#if !defined(USE_ESP32) && !defined(USE_HOST) && !defined(USE_ZEPHYR) && !defined(USE_RP2040)
-uint64_t Scheduler::millis_64_impl_(uint32_t now) {
-  // THREAD SAFETY NOTE:
-  // This function has three implementations, based on the precompiler flags
-  // - ESPHOME_THREAD_SINGLE - Runs on single-threaded platforms (ESP8266, RP2040, etc.)
-  // - ESPHOME_THREAD_MULTI_NO_ATOMICS - Runs on multi-threaded platforms without atomics (LibreTiny BK72xx)
-  // - ESPHOME_THREAD_MULTI_ATOMICS - Runs on multi-threaded platforms with atomics (ESP32, HOST, LibreTiny
-  // RTL87xx/LN882x, etc.)
-  //
-  // Make sure all changes are synchronized if you edit this function.
-  //
-  // IMPORTANT: Always pass fresh millis() values to this function. The implementation
-  // handles out-of-order timestamps between threads, but minimizing time differences
-  // helps maintain accuracy.
-  //
-
-#ifdef ESPHOME_THREAD_SINGLE
-  // This is the single core implementation.
-  //
-  // Single-core platforms have no concurrency, so this is a simple implementation
-  // that just tracks 32-bit rollover (every 49.7 days) without any locking or atomics.
-
-  uint16_t major = this->millis_major_;
-  uint32_t last = this->last_millis_;
-
-  // Check for rollover
-  if (now < last && (last - now) > HALF_MAX_UINT32) {
-    this->millis_major_++;
-    major++;
-    this->last_millis_ = now;
-#ifdef ESPHOME_DEBUG_SCHEDULER
-    ESP_LOGD(TAG, "Detected true 32-bit rollover at %" PRIu32 "ms (was %" PRIu32 ")", now, last);
-#endif /* ESPHOME_DEBUG_SCHEDULER */
-  } else if (now > last) {
-    // Only update if time moved forward
-    this->last_millis_ = now;
-  }
-
-  // Combine major (high 32 bits) and now (low 32 bits) into 64-bit time
-  return now + (static_cast<uint64_t>(major) << 32);
-
-#elif defined(ESPHOME_THREAD_MULTI_NO_ATOMICS)
-  // This is the multi core no atomics implementation.
-  //
-  // Without atomics, this implementation uses locks more aggressively:
-  // 1. Always locks when near the rollover boundary (within 10 seconds)
-  // 2. Always locks when detecting a large backwards jump
-  // 3. Updates without lock in normal forward progression (accepting minor races)
-  // This is less efficient but necessary without atomic operations.
-  uint16_t major = this->millis_major_;
-  uint32_t last = this->last_millis_;
-
-  // Define a safe window around the rollover point (10 seconds)
-  // This covers any reasonable scheduler delays or thread preemption
-  static constexpr uint32_t ROLLOVER_WINDOW = 10000;  // 10 seconds in milliseconds
-
-  // Check if we're near the rollover boundary (close to std::numeric_limits<uint32_t>::max() or just past 0)
-  bool near_rollover = (last > (std::numeric_limits<uint32_t>::max() - ROLLOVER_WINDOW)) || (now < ROLLOVER_WINDOW);
-
-  if (near_rollover || (now < last && (last - now) > HALF_MAX_UINT32)) {
-    // Near rollover or detected a rollover - need lock for safety
-    LockGuard guard{this->lock_};
-    // Re-read with lock held
-    last = this->last_millis_;
-
-    if (now < last && (last - now) > HALF_MAX_UINT32) {
-      // True rollover detected (happens every ~49.7 days)
-      this->millis_major_++;
-      major++;
-#ifdef ESPHOME_DEBUG_SCHEDULER
-      ESP_LOGD(TAG, "Detected true 32-bit rollover at %" PRIu32 "ms (was %" PRIu32 ")", now, last);
-#endif /* ESPHOME_DEBUG_SCHEDULER */
-    }
-    // Update last_millis_ while holding lock
-    this->last_millis_ = now;
-  } else if (now > last) {
-    // Normal case: Not near rollover and time moved forward
-    // Update without lock. While this may cause minor races (microseconds of
-    // backwards time movement), they're acceptable because:
-    // 1. The scheduler operates at millisecond resolution, not microsecond
-    // 2. We've already prevented the critical rollover race condition
-    // 3. Any backwards movement is orders of magnitude smaller than scheduler delays
-    this->last_millis_ = now;
-  }
-  // If now <= last and we're not near rollover, don't update
-  // This minimizes backwards time movement
-
-  // Combine major (high 32 bits) and now (low 32 bits) into 64-bit time
-  return now + (static_cast<uint64_t>(major) << 32);
-
-#elif defined(ESPHOME_THREAD_MULTI_ATOMICS)
-  // This is the multi core with atomics implementation.
-  //
-  // Uses atomic operations with acquire/release semantics to ensure coherent
-  // reads of millis_major_ and last_millis_ across cores. Features:
-  // 1. Epoch-coherency retry loop to handle concurrent updates
-  // 2. Lock only taken for actual rollover detection and update
-  // 3. Lock-free CAS updates for normal forward time progression
-  // 4. Memory ordering ensures cores see consistent time values
-
-  for (;;) {
-    uint16_t major = this->millis_major_.load(std::memory_order_acquire);
-
-    /*
-     * Acquire so that if we later decide **not** to take the lock we still
-     * observe a `millis_major_` value coherent with the loaded `last_millis_`.
-     * The acquire load ensures any later read of `millis_major_` sees its
-     * corresponding increment.
-     */
-    uint32_t last = this->last_millis_.load(std::memory_order_acquire);
-
-    // If we might be near a rollover (large backwards jump), take the lock for the entire operation
-    // This ensures rollover detection and last_millis_ update are atomic together
-    if (now < last && (last - now) > HALF_MAX_UINT32) {
-      // Potential rollover - need lock for atomic rollover detection + update
-      LockGuard guard{this->lock_};
-      // Re-read with lock held; mutex already provides ordering
-      last = this->last_millis_.load(std::memory_order_relaxed);
-
-      if (now < last && (last - now) > HALF_MAX_UINT32) {
-        // True rollover detected (happens every ~49.7 days)
-        this->millis_major_.fetch_add(1, std::memory_order_relaxed);
-        major++;
-#ifdef ESPHOME_DEBUG_SCHEDULER
-        ESP_LOGD(TAG, "Detected true 32-bit rollover at %" PRIu32 "ms (was %" PRIu32 ")", now, last);
-#endif /* ESPHOME_DEBUG_SCHEDULER */
-      }
-      /*
-       * Update last_millis_ while holding the lock to prevent races
-       * Publish the new low-word *after* bumping `millis_major_` (done above)
-       * so readers never see a mismatched pair.
-       */
-      this->last_millis_.store(now, std::memory_order_release);
-    } else {
-      // Normal case: Try lock-free update, but only allow forward movement within same epoch
-      // This prevents accidentally moving backwards across a rollover boundary
-      while (now > last && (now - last) < HALF_MAX_UINT32) {
-        if (this->last_millis_.compare_exchange_weak(last, now,
-                                                     std::memory_order_release,     // success
-                                                     std::memory_order_relaxed)) {  // failure
-          break;
-        }
-        // CAS failure means no data was published; relaxed is fine
-        // last is automatically updated by compare_exchange_weak if it fails
-      }
-    }
-    uint16_t major_end = this->millis_major_.load(std::memory_order_relaxed);
-    if (major_end == major)
-      return now + (static_cast<uint64_t>(major) << 32);
-  }
-  // Unreachable - the loop always returns when major_end == major
-  __builtin_unreachable();
-
-#else
-#error \
-    "No platform threading model defined. One of ESPHOME_THREAD_SINGLE, ESPHOME_THREAD_MULTI_NO_ATOMICS, or ESPHOME_THREAD_MULTI_ATOMICS must be defined."
-#endif
-}
-#endif  // !USE_ESP32 && !USE_HOST && !USE_ZEPHYR && !USE_RP2040
-
 bool HOT Scheduler::SchedulerItem::cmp(const SchedulerItemPtr &a, const SchedulerItemPtr &b) {
   // High bits are almost always equal (change only on 32-bit rollover ~49 days)
   // Optimize for common case: check low bits first when high bits are equal
diff --git a/esphome/core/scheduler.h b/esphome/core/scheduler.h
index d52cf5147d..cefbdd1b22 100644
--- a/esphome/core/scheduler.h
+++ b/esphome/core/scheduler.h
@@ -12,6 +12,7 @@
 #include "esphome/core/component.h"
 #include "esphome/core/hal.h"
 #include "esphome/core/helpers.h"
+#include "esphome/core/time_64.h"
 
 namespace esphome {
 
@@ -284,23 +285,16 @@ class Scheduler {
   bool cancel_retry_(Component *component, NameType name_type, const char *static_name, uint32_t hash_or_id);
 
   // Extend a 32-bit millis() value to 64-bit. Use when the caller already has a fresh now.
-  // On ESP32, Host, Zephyr, and RP2040, ignores now and uses the native 64-bit time source via millis_64().
+  // On platforms with native 64-bit time, ignores now and uses millis_64() directly.
   // On other platforms, extends now to 64-bit using rollover tracking.
   uint64_t millis_64_from_(uint32_t now) {
-#if defined(USE_ESP32) || defined(USE_HOST) || defined(USE_ZEPHYR) || defined(USE_RP2040)
+#ifdef USE_NATIVE_64BIT_TIME
     (void) now;
     return millis_64();
 #else
-    return this->millis_64_impl_(now);
+    return Millis64Impl::compute(now);
 #endif
   }
-
-#if !defined(USE_ESP32) && !defined(USE_HOST) && !defined(USE_ZEPHYR) && !defined(USE_RP2040)
-  // On platforms without native 64-bit time, millis_64() HAL function delegates to this
-  // method which tracks 32-bit millis() rollover using millis_major_ and last_millis_.
-  friend uint64_t millis_64();
-  uint64_t millis_64_impl_(uint32_t now);
-#endif
   // Cleanup logically deleted items from the scheduler
   // Returns the number of items remaining after cleanup
   // IMPORTANT: This method should only be called from the main thread (loop task).
@@ -566,39 +560,6 @@ class Scheduler {
   //   can stall the entire system, causing timing issues and dropped events for any components that need
   //   to synchronize between tasks (see https://github.com/esphome/backlog/issues/52)
   std::vector<SchedulerItemPtr> scheduler_item_pool_;
-
-#if !defined(USE_ESP32) && !defined(USE_HOST) && !defined(USE_ZEPHYR) && !defined(USE_RP2040)
-  // On platforms with native 64-bit time (ESP32, Host, Zephyr, RP2040), no rollover tracking needed.
-  // On other platforms, these fields track 32-bit millis() rollover for millis_64_impl_().
-#ifdef ESPHOME_THREAD_MULTI_ATOMICS
-  /*
-   * Multi-threaded platforms with atomic support: last_millis_ needs atomic for lock-free updates
-   *
-   * MEMORY-ORDERING NOTE
-   * --------------------
-   * `last_millis_` and `millis_major_` form a single 64-bit timestamp split in half.
-   * Writers publish `last_millis_` with memory_order_release and readers use
-   * memory_order_acquire. This ensures that once a reader sees the new low word,
-   * it also observes the corresponding increment of `millis_major_`.
-   */
-  std::atomic<uint32_t> last_millis_{0};
-#else  /* not ESPHOME_THREAD_MULTI_ATOMICS */
-  // Platforms without atomic support or single-threaded platforms
-  uint32_t last_millis_{0};
-#endif /* else ESPHOME_THREAD_MULTI_ATOMICS */
-
-  /*
-   * Upper 16 bits of the 64-bit millis counter. Incremented only while holding
-   * `lock_`; read concurrently. Atomic (relaxed) avoids a formal data race.
-   * Ordering relative to `last_millis_` is provided by its release store and the
-   * corresponding acquire loads.
-   */
-#ifdef ESPHOME_THREAD_MULTI_ATOMICS
-  std::atomic<uint16_t> millis_major_{0};
-#else  /* not ESPHOME_THREAD_MULTI_ATOMICS */
-  uint16_t millis_major_{0};
-#endif /* else ESPHOME_THREAD_MULTI_ATOMICS */
-#endif /* !USE_ESP32 && !USE_HOST && !USE_ZEPHYR && !USE_RP2040 */
 };
 
 }  // namespace esphome
diff --git a/esphome/core/string_ref.h b/esphome/core/string_ref.h
index d502c4d27f..6047202753 100644
--- a/esphome/core/string_ref.h
+++ b/esphome/core/string_ref.h
@@ -81,6 +81,20 @@ class StringRef {
 
   operator std::string() const { return str(); }
 
+  /// Compare (compatible with std::string::compare)
+  int compare(const StringRef &other) const {
+    int result = std::memcmp(base_, other.base_, std::min(len_, other.len_));
+    if (result != 0)
+      return result;
+    if (len_ < other.len_)
+      return -1;
+    if (len_ > other.len_)
+      return 1;
+    return 0;
+  }
+  int compare(const char *s) const { return compare(StringRef(s)); }
+  int compare(const std::string &s) const { return compare(StringRef(s)); }
+
   /// Find first occurrence of substring, returns std::string::npos if not found.
   /// Note: Requires the underlying string to be null-terminated.
   size_type find(const char *s, size_type pos = 0) const {
diff --git a/esphome/core/time_64.cpp b/esphome/core/time_64.cpp
new file mode 100644
index 0000000000..db5df25eb9
--- /dev/null
+++ b/esphome/core/time_64.cpp
@@ -0,0 +1,207 @@
+#include "esphome/core/defines.h"
+
+#ifndef USE_NATIVE_64BIT_TIME
+
+#include "time_64.h"
+
+#include "esphome/core/helpers.h"
+#ifdef ESPHOME_DEBUG_SCHEDULER
+#include "esphome/core/log.h"
+#include <cinttypes>
+#endif
+#ifdef ESPHOME_THREAD_MULTI_ATOMICS
+#include <atomic>
+#endif
+#include <limits>
+
+namespace esphome {
+
+#ifdef ESPHOME_DEBUG_SCHEDULER
+static const char *const TAG = "time_64";
+#endif
+
+uint64_t Millis64Impl::compute(uint32_t now) {
+  // Half the 32-bit range - used to detect rollovers vs normal time progression
+  static constexpr uint32_t HALF_MAX_UINT32 = std::numeric_limits<uint32_t>::max() / 2;
+
+  // State variables for rollover tracking - static to persist across calls
+#ifdef ESPHOME_THREAD_MULTI_ATOMICS
+  // Mutex for rollover serialization (taken only every ~49.7 days).
+  // A spinlock would be smaller (~1 byte vs ~80-100 bytes) but is unsafe on
+  // preemptive single-core RTOS platforms due to priority inversion: a high-priority
+  // task spinning would prevent the lock holder from running to release it.
+  static Mutex lock;
+  /*
+   * Multi-threaded platforms with atomic support: last_millis needs atomic for lock-free updates.
+   * Writers publish last_millis with memory_order_release and readers use memory_order_acquire.
+   * This ensures that once a reader sees the new low word, it also observes the corresponding
+   * increment of millis_major.
+   */
+  static std::atomic<uint32_t> last_millis{0};
+  /*
+   * Upper 16 bits of the 64-bit millis counter. Incremented only while holding lock;
+   * read concurrently. Atomic (relaxed) avoids a formal data race. Ordering relative
+   * to last_millis is provided by its release store and the corresponding acquire loads.
+   */
+  static std::atomic<uint16_t> millis_major{0};
+#elif !defined(ESPHOME_THREAD_SINGLE) /* ESPHOME_THREAD_MULTI_NO_ATOMICS */
+  static Mutex lock;
+  static uint32_t last_millis{0};
+  static uint16_t millis_major{0};
+#else                                 /* ESPHOME_THREAD_SINGLE */
+  static uint32_t last_millis{0};
+  static uint16_t millis_major{0};
+#endif
+
+  // THREAD SAFETY NOTE:
+  // This function has three implementations, based on the precompiler flags
+  // - ESPHOME_THREAD_SINGLE - Runs on single-threaded platforms (ESP8266, etc.)
+  // - ESPHOME_THREAD_MULTI_NO_ATOMICS - Runs on multi-threaded platforms without atomics (LibreTiny BK72xx)
+  // - ESPHOME_THREAD_MULTI_ATOMICS - Runs on multi-threaded platforms with atomics (LibreTiny RTL87xx/LN882x, etc.)
+  //
+  // Make sure all changes are synchronized if you edit this function.
+  //
+  // IMPORTANT: Always pass fresh millis() values to this function. The implementation
+  // handles out-of-order timestamps between threads, but minimizing time differences
+  // helps maintain accuracy.
+
+#ifdef ESPHOME_THREAD_SINGLE
+  // Single-core platforms have no concurrency, so this is a simple implementation
+  // that just tracks 32-bit rollover (every 49.7 days) without any locking or atomics.
+
+  uint16_t major = millis_major;
+  uint32_t last = last_millis;
+
+  // Check for rollover
+  if (now < last && (last - now) > HALF_MAX_UINT32) {
+    millis_major++;
+    major++;
+    last_millis = now;
+#ifdef ESPHOME_DEBUG_SCHEDULER
+    ESP_LOGD(TAG, "Detected true 32-bit rollover at %" PRIu32 "ms (was %" PRIu32 ")", now, last);
+#endif /* ESPHOME_DEBUG_SCHEDULER */
+  } else if (now > last) {
+    // Only update if time moved forward
+    last_millis = now;
+  }
+
+  // Combine major (high 32 bits) and now (low 32 bits) into 64-bit time
+  return now + (static_cast<uint64_t>(major) << 32);
+
+#elif defined(ESPHOME_THREAD_MULTI_NO_ATOMICS)
+  // Without atomics, this implementation uses locks more aggressively:
+  // 1. Always locks when near the rollover boundary (within 10 seconds)
+  // 2. Always locks when detecting a large backwards jump
+  // 3. Updates without lock in normal forward progression (accepting minor races)
+  // This is less efficient but necessary without atomic operations.
+  uint16_t major = millis_major;
+  uint32_t last = last_millis;
+
+  // Define a safe window around the rollover point (10 seconds)
+  // This covers any reasonable scheduler delays or thread preemption
+  static constexpr uint32_t ROLLOVER_WINDOW = 10000;  // 10 seconds in milliseconds
+
+  // Check if we're near the rollover boundary (close to std::numeric_limits<uint32_t>::max() or just past 0)
+  bool near_rollover = (last > (std::numeric_limits<uint32_t>::max() - ROLLOVER_WINDOW)) || (now < ROLLOVER_WINDOW);
+
+  if (near_rollover || (now < last && (last - now) > HALF_MAX_UINT32)) {
+    // Near rollover or detected a rollover - need lock for safety
+    LockGuard guard{lock};
+    // Re-read with lock held
+    last = last_millis;
+
+    if (now < last && (last - now) > HALF_MAX_UINT32) {
+      // True rollover detected (happens every ~49.7 days)
+      millis_major++;
+      major++;
+#ifdef ESPHOME_DEBUG_SCHEDULER
+      ESP_LOGD(TAG, "Detected true 32-bit rollover at %" PRIu32 "ms (was %" PRIu32 ")", now, last);
+#endif /* ESPHOME_DEBUG_SCHEDULER */
+    }
+    // Update last_millis while holding lock
+    last_millis = now;
+  } else if (now > last) {
+    // Normal case: Not near rollover and time moved forward
+    // Update without lock. While this may cause minor races (microseconds of
+    // backwards time movement), they're acceptable because:
+    // 1. The scheduler operates at millisecond resolution, not microsecond
+    // 2. We've already prevented the critical rollover race condition
+    // 3. Any backwards movement is orders of magnitude smaller than scheduler delays
+    last_millis = now;
+  }
+  // If now <= last and we're not near rollover, don't update
+  // This minimizes backwards time movement
+
+  // Combine major (high 32 bits) and now (low 32 bits) into 64-bit time
+  return now + (static_cast<uint64_t>(major) << 32);
+
+#elif defined(ESPHOME_THREAD_MULTI_ATOMICS)
+  // Uses atomic operations with acquire/release semantics to ensure coherent
+  // reads of millis_major and last_millis across cores. Features:
+  // 1. Epoch-coherency retry loop to handle concurrent updates
+  // 2. Lock only taken for actual rollover detection and update
+  // 3. Lock-free CAS updates for normal forward time progression
+  // 4. Memory ordering ensures cores see consistent time values
+
+  for (;;) {
+    uint16_t major = millis_major.load(std::memory_order_acquire);
+
+    /*
+     * Acquire so that if we later decide **not** to take the lock we still
+     * observe a millis_major value coherent with the loaded last_millis.
+     * The acquire load ensures any later read of millis_major sees its
+     * corresponding increment.
+     */
+    uint32_t last = last_millis.load(std::memory_order_acquire);
+
+    // If we might be near a rollover (large backwards jump), take the lock
+    // This ensures rollover detection and last_millis update are atomic together
+    if (now < last && (last - now) > HALF_MAX_UINT32) {
+      // Potential rollover - need lock for atomic rollover detection + update
+      LockGuard guard{lock};
+      // Re-read with lock held; mutex already provides ordering
+      last = last_millis.load(std::memory_order_relaxed);
+
+      if (now < last && (last - now) > HALF_MAX_UINT32) {
+        // True rollover detected (happens every ~49.7 days)
+        millis_major.fetch_add(1, std::memory_order_relaxed);
+        major++;
+#ifdef ESPHOME_DEBUG_SCHEDULER
+        ESP_LOGD(TAG, "Detected true 32-bit rollover at %" PRIu32 "ms (was %" PRIu32 ")", now, last);
+#endif /* ESPHOME_DEBUG_SCHEDULER */
+      }
+      /*
+       * Update last_millis while holding the lock to prevent races.
+       * Publish the new low-word *after* bumping millis_major (done above)
+       * so readers never see a mismatched pair.
+       */
+      last_millis.store(now, std::memory_order_release);
+    } else {
+      // Normal case: Try lock-free update, but only allow forward movement within same epoch
+      // This prevents accidentally moving backwards across a rollover boundary
+      while (now > last && (now - last) < HALF_MAX_UINT32) {
+        if (last_millis.compare_exchange_weak(last, now,
+                                              std::memory_order_release,     // success
+                                              std::memory_order_relaxed)) {  // failure
+          break;
+        }
+        // CAS failure means no data was published; relaxed is fine
+        // last is automatically updated by compare_exchange_weak if it fails
+      }
+    }
+    uint16_t major_end = millis_major.load(std::memory_order_relaxed);
+    if (major_end == major)
+      return now + (static_cast<uint64_t>(major) << 32);
+  }
+  // Unreachable - the loop always returns when major_end == major
+  __builtin_unreachable();
+
+#else
+#error \
+    "No platform threading model defined. One of ESPHOME_THREAD_SINGLE, ESPHOME_THREAD_MULTI_NO_ATOMICS, or ESPHOME_THREAD_MULTI_ATOMICS must be defined."
+#endif
+}
+
+}  // namespace esphome
+
+#endif  // !USE_NATIVE_64BIT_TIME
diff --git a/esphome/core/time_64.h b/esphome/core/time_64.h
new file mode 100644
index 0000000000..42d4b041e5
--- /dev/null
+++ b/esphome/core/time_64.h
@@ -0,0 +1,24 @@
+#pragma once
+#include "esphome/core/defines.h"
+
+#ifndef USE_NATIVE_64BIT_TIME
+
+#include <cstdint>
+
+namespace esphome {
+
+class Scheduler;
+
+/// Extends 32-bit millis() to 64-bit using rollover tracking.
+/// Access restricted to platform HAL (millis_64()) and Scheduler.
+/// All other code should call millis_64() from hal.h instead.
+class Millis64Impl {
+  friend uint64_t millis_64();
+  friend class Scheduler;
+
+  static uint64_t compute(uint32_t now);
+};
+
+}  // namespace esphome
+
+#endif  // !USE_NATIVE_64BIT_TIME
diff --git a/esphome/cpp_generator.py b/esphome/cpp_generator.py
index fe666bdd6e..5457485d25 100644
--- a/esphome/cpp_generator.py
+++ b/esphome/cpp_generator.py
@@ -247,6 +247,23 @@ class LogStringLiteral(Literal):
         return f"LOG_STR({cpp_string_escape(self.string)})"
 
 
+class FlashStringLiteral(Literal):
+    """A string literal wrapped in ESPHOME_F() for PROGMEM storage on ESP8266.
+
+    On ESP8266, ESPHOME_F(s) expands to F(s) which stores the string in flash (PROGMEM).
+    On other platforms, ESPHOME_F(s) expands to plain s (no-op).
+    """
+
+    __slots__ = ("string",)
+
+    def __init__(self, string: str) -> None:
+        super().__init__()
+        self.string = string
+
+    def __str__(self) -> str:
+        return f"ESPHOME_F({cpp_string_escape(self.string)})"
+
+
 class IntLiteral(Literal):
     __slots__ = ("i",)
 
@@ -761,6 +778,15 @@ async def templatable(
     if is_template(value):
         return await process_lambda(value, args, return_type=output_type)
     if to_exp is None:
+        # Automatically wrap static strings in ESPHOME_F() for PROGMEM storage on ESP8266.
+        # On other platforms ESPHOME_F() is a no-op returning const char*.
+        # Lazy import to avoid circular dependency (cpp_generator <-> cpp_types).
+        # Identity check (is) avoids brittle string comparison.
+        if isinstance(value, str) and output_type is not None:
+            from esphome.cpp_types import std_string
+
+            if output_type is std_string:
+                return FlashStringLiteral(value)
         return value
     if isinstance(to_exp, dict):
         return to_exp[value]
diff --git a/esphome/cpp_helpers.py b/esphome/cpp_helpers.py
index b673eaa7e1..8f8c693140 100644
--- a/esphome/cpp_helpers.py
+++ b/esphome/cpp_helpers.py
@@ -80,6 +80,11 @@ async def register_component(var, config):
         add(var.set_component_source(LogStringLiteral(name)))
 
     add(App.register_component_(var))
+
+    # Collect C++ type for compile-time looping component count
+    comp_entries = CORE.data.setdefault("looping_component_entries", [])
+    comp_entries.append(str(var.base.type))
+
     return var
 
 
diff --git a/esphome/external_files.py b/esphome/external_files.py
index 80b54ebb2f..72a3f33fdc 100644
--- a/esphome/external_files.py
+++ b/esphome/external_files.py
@@ -55,10 +55,12 @@ def has_remote_file_changed(url: str, local_file_path: Path) -> bool:
             _LOGGER.debug("has_remote_file_changed: File modified")
             return True
         except requests.exceptions.RequestException as e:
-            raise cv.Invalid(
-                f"Could not check if {url} has changed, please check if file exists "
-                f"({e})"
+            _LOGGER.warning(
+                "Could not check if %s has changed due to network error (%s), using cached file",
+                url,
+                e,
             )
+            return False
 
     _LOGGER.debug("has_remote_file_changed: File doesn't exists at %s", local_file_path)
     return True
@@ -98,6 +100,13 @@ def download_content(url: str, path: Path, timeout=NETWORK_TIMEOUT) -> bytes:
         )
         req.raise_for_status()
     except requests.exceptions.RequestException as e:
+        if path.exists():
+            _LOGGER.warning(
+                "Could not download from %s due to network error (%s), using cached file",
+                url,
+                e,
+            )
+            return path.read_bytes()
         raise cv.Invalid(f"Could not download from {url}: {e}")
 
     path.parent.mkdir(parents=True, exist_ok=True)
diff --git a/esphome/util.py b/esphome/util.py
index 7b896de27e..686aa74306 100644
--- a/esphome/util.py
+++ b/esphome/util.py
@@ -24,11 +24,14 @@ class RegistryEntry:
         fun: Callable[..., Any],
         type_id: "MockObjClass",
         schema: "Schema",
+        *,
+        synchronous: bool = False,
     ):
         self.name = name
         self.fun = fun
         self.type_id = type_id
         self.raw_schema = schema
+        self.synchronous = synchronous
 
     @property
     def coroutine_fun(self):
@@ -49,9 +52,18 @@ class Registry(dict[str, RegistryEntry]):
         self.base_schema = base_schema or {}
         self.type_id_key = type_id_key
 
-    def register(self, name: str, type_id: "MockObjClass", schema: "Schema"):
+    def register(
+        self,
+        name: str,
+        type_id: "MockObjClass",
+        schema: "Schema",
+        *,
+        synchronous: bool = False,
+    ):
         def decorator(fun: Callable[..., Any]):
-            self[name] = RegistryEntry(name, fun, type_id, schema)
+            self[name] = RegistryEntry(
+                name, fun, type_id, schema, synchronous=synchronous
+            )
             return fun
 
         return decorator
diff --git a/script/api_protobuf/api_protobuf.py b/script/api_protobuf/api_protobuf.py
index 350947a8d6..9c9cda4d36 100755
--- a/script/api_protobuf/api_protobuf.py
+++ b/script/api_protobuf/api_protobuf.py
@@ -2473,9 +2473,6 @@ def build_base_class(
     out = f"class {base_class_name} : public {parent_class} {{\n"
     out += " public:\n"
 
-    # Add destructor with override
-    public_content.insert(0, f"~{base_class_name}() override = default;")
-
     # Base classes don't implement encode/decode/calculate_size
     # Derived classes handle these with their specific field numbers
     cpp = ""
@@ -2483,6 +2480,8 @@ def build_base_class(
     out += indent("\n".join(public_content)) + "\n"
     out += "\n"
     out += " protected:\n"
+    # Non-virtual protected destructor prevents accidental polymorphic deletion
+    protected_content.insert(0, f"~{base_class_name}() = default;")
     out += indent("\n".join(protected_content))
     if protected_content:
         out += "\n"
diff --git a/tests/integration/fixtures/external_components/uart_mock/__init__.py b/tests/integration/fixtures/external_components/uart_mock/__init__.py
new file mode 100644
index 0000000000..dea8c38551
--- /dev/null
+++ b/tests/integration/fixtures/external_components/uart_mock/__init__.py
@@ -0,0 +1,165 @@
+from esphome import automation
+import esphome.codegen as cg
+from esphome.components import uart
+from esphome.components.uart import (
+    CONF_RX_FULL_THRESHOLD,
+    CONF_RX_TIMEOUT,
+    debug_to_code,
+    maybe_empty_debug,
+    validate_raw_data,
+)
+import esphome.config_validation as cv
+from esphome.const import (
+    CONF_BAUD_RATE,
+    CONF_DATA,
+    CONF_DATA_BITS,
+    CONF_DEBUG,
+    CONF_DELAY,
+    CONF_ID,
+    CONF_INTERVAL,
+    CONF_PARITY,
+    CONF_RX_BUFFER_SIZE,
+    CONF_STOP_BITS,
+    CONF_TRIGGER_ID,
+)
+from esphome.core import ID
+
+CODEOWNERS = ["@esphome/tests"]
+MULTI_CONF = True
+
+uart_mock_ns = cg.esphome_ns.namespace("uart_mock")
+MockUartComponent = uart_mock_ns.class_(
+    "MockUartComponent", uart.UARTComponent, cg.Component
+)
+MockUartInjectRXAction = uart_mock_ns.class_(
+    "MockUartInjectRXAction", automation.Action
+)
+MockUartTXTrigger = uart_mock_ns.class_(
+    "MockUartTXTrigger",
+    automation.Trigger.template(cg.std_vector.template(cg.uint8)),
+)
+
+CONF_INJECTIONS = "injections"
+CONF_RESPONSES = "responses"
+CONF_INJECT_RX = "inject_rx"
+CONF_EXPECT_TX = "expect_tx"
+CONF_PERIODIC_RX = "periodic_rx"
+CONF_ON_TX = "on_tx"
+
+UART_PARITY_OPTIONS = {
+    "NONE": uart.UARTParityOptions.UART_CONFIG_PARITY_NONE,
+    "EVEN": uart.UARTParityOptions.UART_CONFIG_PARITY_EVEN,
+    "ODD": uart.UARTParityOptions.UART_CONFIG_PARITY_ODD,
+}
+
+INJECTION_SCHEMA = cv.Schema(
+    {
+        cv.Required(CONF_INJECT_RX): [cv.hex_uint8_t],
+        cv.Optional(CONF_DELAY, default="0ms"): cv.positive_time_period_milliseconds,
+    }
+)
+
+CONFIG_INJECT_RX_SCHEMA = cv.maybe_simple_value(
+    {
+        cv.GenerateID(): cv.use_id(MockUartComponent),
+        cv.Required("data"): cv.templatable(validate_raw_data),
+    },
+    key=CONF_DATA,
+)
+
+
+RESPONSE_SCHEMA = cv.Schema(
+    {
+        cv.Required(CONF_EXPECT_TX): [cv.hex_uint8_t],
+        cv.Required(CONF_INJECT_RX): [cv.hex_uint8_t],
+    }
+)
+
+PERIODIC_RX_SCHEMA = cv.Schema(
+    {
+        cv.Required(CONF_DATA): [cv.hex_uint8_t],
+        cv.Required(CONF_INTERVAL): cv.positive_time_period_milliseconds,
+    }
+)
+
+CONFIG_SCHEMA = cv.Schema(
+    {
+        cv.GenerateID(): cv.declare_id(MockUartComponent),
+        cv.Required(CONF_BAUD_RATE): cv.int_range(min=1),
+        cv.Optional(CONF_RX_BUFFER_SIZE, default=256): cv.validate_bytes,
+        cv.Optional(CONF_RX_FULL_THRESHOLD, default=10): cv.int_range(min=1, max=120),
+        cv.Optional(CONF_RX_TIMEOUT, default=2): cv.int_range(min=0, max=92),
+        cv.Optional(CONF_STOP_BITS, default=1): cv.one_of(1, 2, int=True),
+        cv.Optional(CONF_DATA_BITS, default=8): cv.int_range(min=5, max=8),
+        cv.Optional(CONF_PARITY, default="NONE"): cv.enum(
+            UART_PARITY_OPTIONS, upper=True
+        ),
+        cv.Optional(CONF_INJECTIONS, default=[]): cv.ensure_list(INJECTION_SCHEMA),
+        cv.Optional(CONF_RESPONSES, default=[]): cv.ensure_list(RESPONSE_SCHEMA),
+        cv.Optional(CONF_PERIODIC_RX, default=[]): cv.ensure_list(PERIODIC_RX_SCHEMA),
+        cv.Optional(CONF_ON_TX): automation.validate_automation(
+            {
+                cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(MockUartTXTrigger),
+            }
+        ),
+        cv.Optional(CONF_DEBUG): maybe_empty_debug,
+    }
+).extend(cv.COMPONENT_SCHEMA)
+
+
+@automation.register_action(
+    "uart_mock.inject_rx", MockUartInjectRXAction, CONFIG_INJECT_RX_SCHEMA
+)
+async def inject_rx_to_code(config, action_id, template_arg, args):
+    var = cg.new_Pvariable(action_id, template_arg)
+    await cg.register_parented(var, config[CONF_ID])
+    data = config[CONF_DATA]
+    if isinstance(data, bytes):
+        data = list(data)
+
+    if cg.is_template(data):
+        templ = await cg.templatable(data, args, cg.std_vector.template(cg.uint8))
+        cg.add(var.set_data_template(templ))
+    else:
+        # Generate static array in flash to avoid RAM copy
+        arr_id = ID(f"{action_id}_data", is_declaration=True, type=cg.uint8)
+        arr = cg.static_const_array(arr_id, cg.ArrayInitializer(*data))
+        cg.add(var.set_data_static(arr, len(data)))
+    return var
+
+
+async def to_code(config):
+    var = cg.new_Pvariable(config[CONF_ID])
+    await cg.register_component(var, config)
+
+    cg.add(var.set_baud_rate(config[CONF_BAUD_RATE]))
+    cg.add(var.set_rx_buffer_size(config[CONF_RX_BUFFER_SIZE]))
+    cg.add(var.set_rx_full_threshold(config[CONF_RX_FULL_THRESHOLD]))
+    cg.add(var.set_rx_timeout(config[CONF_RX_TIMEOUT]))
+    cg.add(var.set_stop_bits(config[CONF_STOP_BITS]))
+    cg.add(var.set_data_bits(config[CONF_DATA_BITS]))
+    cg.add(var.set_parity(config[CONF_PARITY]))
+
+    for injection in config[CONF_INJECTIONS]:
+        rx_data = injection[CONF_INJECT_RX]
+        delay_ms = injection[CONF_DELAY]
+        cg.add(var.add_injection(rx_data, delay_ms))
+
+    for response in config[CONF_RESPONSES]:
+        tx_data = response[CONF_EXPECT_TX]
+        rx_data = response[CONF_INJECT_RX]
+        cg.add(var.add_response(tx_data, rx_data))
+
+    for periodic in config[CONF_PERIODIC_RX]:
+        data = periodic[CONF_DATA]
+        interval = periodic[CONF_INTERVAL]
+        cg.add(var.add_periodic_rx(data, interval))
+
+    for conf in config.get(CONF_ON_TX, []):
+        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
+        await automation.build_automation(
+            trigger, [(cg.std_vector.template(cg.uint8), "data")], conf
+        )
+
+    if CONF_DEBUG in config:
+        await debug_to_code(config[CONF_DEBUG], var)
diff --git a/tests/integration/fixtures/external_components/uart_mock/automation.h b/tests/integration/fixtures/external_components/uart_mock/automation.h
new file mode 100644
index 0000000000..83a057d3a0
--- /dev/null
+++ b/tests/integration/fixtures/external_components/uart_mock/automation.h
@@ -0,0 +1,51 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/core/automation.h"
+#include "uart_mock.h"
+
+namespace esphome::uart_mock {
+
+// This pattern is similar to UARTWriteAction but calls inject_rx instead of write_array, and is parented to VirtualUART
+// instead of UARTComponent
+template<typename... Ts> class MockUartInjectRXAction : public Action<Ts...>, public Parented<MockUartComponent> {
+ public:
+  void set_data_template(std::vector<uint8_t> (*func)(Ts...)) {
+    // Stateless lambdas (generated by ESPHome) implicitly convert to function pointers
+    this->code_.func = func;
+    this->len_ = -1;  // Sentinel value indicates template mode
+  }
+
+  // Store pointer to static data in flash (no RAM copy)
+  void set_data_static(const uint8_t *data, size_t len) {
+    this->code_.data = data;
+    this->len_ = len;  // Length >= 0 indicates static mode
+  }
+
+  void play(const Ts &...x) override {
+    if (this->len_ >= 0) {
+      // Static mode: use pointer and length
+      this->parent_->inject_to_rx_buffer(this->code_.data, static_cast<size_t>(this->len_));
+    } else {
+      // Template mode: call function
+      auto val = this->code_.func(x...);
+      this->parent_->inject_to_rx_buffer(val);
+    }
+  }
+
+ protected:
+  ssize_t len_{-1};  // -1 = template mode, >=0 = static mode with length
+  union Code {
+    std::vector<uint8_t> (*func)(Ts...);  // Function pointer (stateless lambdas)
+    const uint8_t *data;                  // Pointer to static data in flash
+  } code_;
+};
+
+class MockUartTXTrigger : public Trigger<std::vector<uint8_t>> {
+ public:
+  explicit MockUartTXTrigger(MockUartComponent *parent) {
+    parent->set_tx_hook([this](std::vector<uint8_t> data) { this->trigger(data); });
+  }
+};
+
+}  // namespace esphome::uart_mock
diff --git a/tests/integration/fixtures/external_components/uart_mock/uart_mock.cpp b/tests/integration/fixtures/external_components/uart_mock/uart_mock.cpp
new file mode 100644
index 0000000000..a4a1c41234
--- /dev/null
+++ b/tests/integration/fixtures/external_components/uart_mock/uart_mock.cpp
@@ -0,0 +1,176 @@
+// Host-only test component — do not copy to production code.
+// See uart_mock.h for details.
+
+#include "uart_mock.h"
+#include "esphome/core/application.h"
+#include "esphome/core/helpers.h"
+#include "esphome/core/log.h"
+
+namespace esphome::uart_mock {
+
+static const char *const TAG = "uart_mock";
+
+void MockUartComponent::setup() {
+  ESP_LOGI(TAG, "Mock UART initialized with %zu injections, %zu responses, %zu periodic", this->injections_.size(),
+           this->responses_.size(), this->periodic_rx_.size());
+}
+
+void MockUartComponent::loop() {
+  uint32_t now = App.get_loop_component_start_time();
+
+  // Initialize scenario start time on first loop() call, after all components have
+  // finished setup(). This prevents injection delays from being consumed during setup.
+  if (!this->loop_started_) {
+    this->loop_started_ = true;
+    this->scenario_start_ms_ = now;
+    this->cumulative_delay_ms_ = 0;
+    ESP_LOGD(TAG, "Scenario started at %u ms", now);
+  }
+
+  // Process at most ONE timed injection per loop iteration.
+  // This ensures each injection is in a separate loop cycle, giving the consuming
+  // component (e.g., LD2410) a chance to process each batch independently.
+  if (this->injection_index_ < this->injections_.size()) {
+    auto &injection = this->injections_[this->injection_index_];
+    uint32_t target_time = this->scenario_start_ms_ + this->cumulative_delay_ms_ + injection.delay_ms;
+    if (now >= target_time) {
+      ESP_LOGD(TAG, "Injecting %zu RX bytes (injection %u)", injection.rx_data.size(), this->injection_index_);
+      this->inject_to_rx_buffer(injection.rx_data);
+      this->cumulative_delay_ms_ += injection.delay_ms;
+      this->injection_index_++;
+    }
+  }
+
+  // Process periodic RX
+  for (auto &periodic : this->periodic_rx_) {
+    if (now - periodic.last_inject_ms >= periodic.interval_ms) {
+      this->inject_to_rx_buffer(periodic.data);
+      periodic.last_inject_ms = now;
+    }
+  }
+}
+
+void MockUartComponent::dump_config() {
+  ESP_LOGCONFIG(TAG,
+                "Mock UART Component:\n"
+                "  Baud Rate: %u\n"
+                "  Injections: %zu\n"
+                "  Responses: %zu\n"
+                "  Periodic RX: %zu",
+                this->baud_rate_, this->injections_.size(), this->responses_.size(), this->periodic_rx_.size());
+}
+
+void MockUartComponent::write_array(const uint8_t *data, size_t len) {
+  this->tx_count_ += len;
+  this->tx_buffer_.insert(this->tx_buffer_.end(), data, data + len);
+
+  // Log all TX data so tests can verify what the component sends
+  if (len > 0 && len <= 64) {
+    char hex_buf[format_hex_pretty_size(64)];
+    ESP_LOGD(TAG, "TX %zu bytes: %s", len, format_hex_pretty_to(hex_buf, sizeof(hex_buf), data, len));
+  } else if (len > 64) {
+    ESP_LOGD(TAG, "TX %zu bytes (too large to log)", len);
+  }
+
+#ifdef USE_UART_DEBUGGER
+  for (size_t i = 0; i < len; i++) {
+    this->debug_callback_.call(uart::UART_DIRECTION_TX, data[i]);
+  }
+#endif
+
+  this->try_match_response_();
+
+  // This directly calls a tx_hook (lambda) as an alternative to the simpler match_response mechanism.
+  if (this->tx_hook_) {
+    std::vector<uint8_t> buf(data, data + len);
+    this->tx_hook_(buf);
+  }
+}
+
+bool MockUartComponent::peek_byte(uint8_t *data) {
+  if (this->rx_buffer_.empty()) {
+    return false;
+  }
+  *data = this->rx_buffer_.front();
+  return true;
+}
+
+bool MockUartComponent::read_array(uint8_t *data, size_t len) {
+  if (this->rx_buffer_.size() < len) {
+    return false;
+  }
+  for (size_t i = 0; i < len; i++) {
+    data[i] = this->rx_buffer_.front();
+    this->rx_buffer_.pop_front();
+  }
+  this->rx_count_ += len;
+
+#ifdef USE_UART_DEBUGGER
+  for (size_t i = 0; i < len; i++) {
+    this->debug_callback_.call(uart::UART_DIRECTION_RX, data[i]);
+  }
+#endif
+
+  return true;
+}
+
+size_t MockUartComponent::available() { return this->rx_buffer_.size(); }
+
+void MockUartComponent::flush() {
+  // Nothing to flush in mock
+}
+
+void MockUartComponent::set_rx_full_threshold(size_t rx_full_threshold) {
+  this->rx_full_threshold_ = rx_full_threshold;
+}
+
+void MockUartComponent::set_rx_timeout(size_t rx_timeout) { this->rx_timeout_ = rx_timeout; }
+
+void MockUartComponent::add_injection(const std::vector<uint8_t> &rx_data, uint32_t delay_ms) {
+  this->injections_.push_back({rx_data, delay_ms});
+}
+
+void MockUartComponent::add_response(const std::vector<uint8_t> &expect_tx, const std::vector<uint8_t> &inject_rx) {
+  this->responses_.push_back({expect_tx, inject_rx});
+}
+
+void MockUartComponent::add_periodic_rx(const std::vector<uint8_t> &data, uint32_t interval_ms) {
+  this->periodic_rx_.push_back({data, interval_ms, 0});
+}
+
+void MockUartComponent::try_match_response_() {
+  for (auto &response : this->responses_) {
+    if (this->tx_buffer_.size() < response.expect_tx.size()) {
+      continue;
+    }
+    // Check if tx_buffer_ ends with expect_tx
+    size_t offset = this->tx_buffer_.size() - response.expect_tx.size();
+    if (std::equal(response.expect_tx.begin(), response.expect_tx.end(), this->tx_buffer_.begin() + offset)) {
+      ESP_LOGD(TAG, "TX match found, injecting %zu RX bytes", response.inject_rx.size());
+      this->inject_to_rx_buffer(response.inject_rx);
+      this->tx_buffer_.clear();
+      return;
+    }
+  }
+}
+
+void MockUartComponent::inject_to_rx_buffer(const uint8_t *data, size_t len) {
+  std::vector<uint8_t> vec(data, data + len);
+  this->inject_to_rx_buffer(vec);
+}
+
+void MockUartComponent::inject_to_rx_buffer(const std::vector<uint8_t> &data) {
+  // Log injected RX data so tests can see what's being fed to the component
+  if (!data.empty() && data.size() <= 64) {
+    char hex_buf[format_hex_pretty_size(64)];
+    ESP_LOGD(TAG, "RX inject %zu bytes: %s", data.size(),
+             format_hex_pretty_to(hex_buf, sizeof(hex_buf), data.data(), data.size()));
+  } else if (data.size() > 64) {
+    ESP_LOGD(TAG, "RX inject %zu bytes (too large to log inline)", data.size());
+  }
+  for (uint8_t byte : data) {
+    this->rx_buffer_.push_back(byte);
+  }
+}
+
+}  // namespace esphome::uart_mock
diff --git a/tests/integration/fixtures/external_components/uart_mock/uart_mock.h b/tests/integration/fixtures/external_components/uart_mock/uart_mock.h
new file mode 100644
index 0000000000..5bbc3c1bf6
--- /dev/null
+++ b/tests/integration/fixtures/external_components/uart_mock/uart_mock.h
@@ -0,0 +1,86 @@
+#pragma once
+
+// ============================================================================
+// HOST-ONLY TEST COMPONENT — DO NOT COPY TO PRODUCTION CODE
+//
+// This component runs exclusively on the host platform for integration testing.
+// It intentionally uses std::vector, std::deque, and dynamic allocation which
+// would be inappropriate for production embedded components. Do not use this
+// code as a reference for writing ESPHome components targeting real hardware.
+// ============================================================================
+
+#include "esphome/core/component.h"
+#include "esphome/components/uart/uart_component.h"
+#include <deque>
+#include <vector>
+
+namespace esphome::uart_mock {
+
+class MockUartComponent : public uart::UARTComponent, public Component {
+ public:
+  void setup() override;
+  void loop() override;
+  void dump_config() override;
+  float get_setup_priority() const override { return setup_priority::BUS; }
+
+  // UARTComponent interface
+  void write_array(const uint8_t *data, size_t len) override;
+  bool peek_byte(uint8_t *data) override;
+  bool read_array(uint8_t *data, size_t len) override;
+  size_t available() override;
+  void flush() override;
+  void set_rx_full_threshold(size_t rx_full_threshold) override;
+  void set_rx_timeout(size_t rx_timeout) override;
+
+  // Scenario configuration - called from generated code
+  void add_injection(const std::vector<uint8_t> &rx_data, uint32_t delay_ms);
+  void add_response(const std::vector<uint8_t> &expect_tx, const std::vector<uint8_t> &inject_rx);
+  void add_periodic_rx(const std::vector<uint8_t> &data, uint32_t interval_ms);
+
+  void set_tx_hook(std::function<void(const std::vector<uint8_t> &)> &&cb) { this->tx_hook_ = std::move(cb); }
+  void inject_to_rx_buffer(const std::vector<uint8_t> &data);
+  void inject_to_rx_buffer(const uint8_t *data, size_t len);
+
+ protected:
+  void check_logger_conflict() override {}
+  void try_match_response_();
+
+  // Timed injections
+  struct Injection {
+    std::vector<uint8_t> rx_data;
+    uint32_t delay_ms;
+  };
+  std::vector<Injection> injections_;
+  uint32_t injection_index_{0};
+  uint32_t scenario_start_ms_{0};
+  uint32_t cumulative_delay_ms_{0};
+  bool loop_started_{false};
+
+  // TX-triggered responses
+  struct Response {
+    std::vector<uint8_t> expect_tx;
+    std::vector<uint8_t> inject_rx;
+  };
+  std::vector<Response> responses_;
+  std::vector<uint8_t> tx_buffer_;
+
+  // RX buffer
+  std::deque<uint8_t> rx_buffer_;
+
+  // Periodic RX
+  struct PeriodicRx {
+    std::vector<uint8_t> data;
+    uint32_t interval_ms;
+    uint32_t last_inject_ms{0};
+  };
+  std::vector<PeriodicRx> periodic_rx_;
+
+  // Observability
+  uint32_t tx_count_{0};
+  uint32_t rx_count_{0};
+
+  // Direct TX hook for tests that want to bypass the response-matching logic
+  std::function<void(const std::vector<uint8_t> &)> tx_hook_;
+};
+
+}  // namespace esphome::uart_mock
diff --git a/tests/integration/fixtures/uart_mock_ld2410.yaml b/tests/integration/fixtures/uart_mock_ld2410.yaml
new file mode 100644
index 0000000000..9a81468263
--- /dev/null
+++ b/tests/integration/fixtures/uart_mock_ld2410.yaml
@@ -0,0 +1,145 @@
+esphome:
+  name: uart-mock-ld2410-test
+
+host:
+api:
+logger:
+  level: VERBOSE
+
+external_components:
+  - source:
+      type: local
+      path: EXTERNAL_COMPONENT_PATH
+
+# Dummy uart entry to satisfy ld2410's DEPENDENCIES = ["uart"]
+# The actual UART bus used is the uart_mock component below
+uart:
+  baud_rate: 115200
+  port: /dev/null
+
+uart_mock:
+  id: mock_uart
+  baud_rate: 256000
+  injections:
+    # Phase 1 (t=100ms): Valid LD2410 normal mode data frame - happy path
+    # The buffer is clean at this point, so this frame should parse correctly.
+    # Moving target: 100cm, energy 50
+    # Still target: 120cm, energy 25
+    # Detection distance: 300cm
+    # Target state: 0x03 (moving + still)
+    #
+    # Note: LD2410's two_byte_to_int() uses signed char, so low bytes must be
+    # <=127 to produce correct values. Values >127 wrap negative.
+    #
+    # Frame layout (24 bytes):
+    #   [0-3]  F4 F3 F2 F1 = data frame header
+    #   [4-5]  0D 00       = length 13
+    #   [6]    02          = data type (normal)
+    #   [7]    AA          = data header marker
+    #   [8]    03          = target states (moving+still)
+    #   [9-10] 64 00       = moving distance 100 (0x0064)
+    #   [11]   32          = moving energy 50
+    #   [12-13] 78 00      = still distance 120 (0x0078)
+    #   [14]   19          = still energy 25
+    #   [15-16] 2C 01      = detection distance 300 (0x012C)
+    #   [17]   00          = padding
+    #   [18]   55          = data footer marker
+    #   [19]   00          = CRC/check
+    #   [20-23] F8 F7 F6 F5 = data frame footer
+    - delay: 100ms
+      inject_rx:
+        [
+          0xF4, 0xF3, 0xF2, 0xF1,
+          0x0D, 0x00,
+          0x02, 0xAA,
+          0x03,
+          0x64, 0x00,
+          0x32,
+          0x78, 0x00,
+          0x19,
+          0x2C, 0x01,
+          0x00,
+          0x55, 0x00,
+          0xF8, 0xF7, 0xF6, 0xF5,
+        ]
+
+    # Phase 2 (t=200ms): Garbage bytes - corrupt the buffer
+    # These random bytes will accumulate in the LD2410's internal buffer.
+    # No footer will be found, so the buffer just grows.
+    - delay: 100ms
+      inject_rx: [0xDE, 0xAD, 0xBE, 0xEF, 0x00, 0x11, 0x22]
+
+    # Phase 3 (t=300ms): Truncated frame (header + partial data, no footer)
+    # More bytes accumulating in the buffer without a footer match.
+    - delay: 100ms
+      inject_rx: [0xF4, 0xF3, 0xF2, 0xF1, 0x0D, 0x00, 0x02, 0xAA]
+
+    # Phase 4 (t=500ms): Overflow - inject 85 bytes of 0xFF (MAX_LINE_LENGTH=50)
+    # Buffer has 15 bytes from phases 2+3.
+    # Overflow math: need 35 bytes to trigger first overflow (pos 15->49),
+    # then 50 more to trigger second overflow (pos 0->49). Total = 85 bytes.
+    # After two overflows, buffer_pos_ = 0 with a completely clean buffer.
+    # The LD2410 logs "Max command length exceeded" at each overflow.
+    - delay: 200ms
+      inject_rx:
+        [
+          0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+          0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+          0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+          0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+          0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+          0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+          0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+          0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+          0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+        ]
+
+    # Phase 5 (t=600ms): Valid frame after overflow - recovery test
+    # Buffer was reset by overflow. This valid frame should parse correctly.
+    # Moving target: 50cm, energy 100
+    # Still target: 75cm, energy 80
+    # Detection distance: 127cm
+    - delay: 100ms
+      inject_rx:
+        [
+          0xF4, 0xF3, 0xF2, 0xF1,
+          0x0D, 0x00,
+          0x02, 0xAA,
+          0x03,
+          0x32, 0x00,
+          0x64,
+          0x4B, 0x00,
+          0x50,
+          0x7F, 0x00,
+          0x00,
+          0x55, 0x00,
+          0xF8, 0xF7, 0xF6, 0xF5,
+        ]
+
+ld2410:
+  id: ld2410_dev
+  uart_id: mock_uart
+
+sensor:
+  - platform: ld2410
+    ld2410_id: ld2410_dev
+    moving_distance:
+      name: "Moving Distance"
+    still_distance:
+      name: "Still Distance"
+    moving_energy:
+      name: "Moving Energy"
+    still_energy:
+      name: "Still Energy"
+    detection_distance:
+      name: "Detection Distance"
+
+binary_sensor:
+  - platform: ld2410
+    ld2410_id: ld2410_dev
+    has_target:
+      name: "Has Target"
+    has_moving_target:
+      name: "Has Moving Target"
+    has_still_target:
+      name: "Has Still Target"
diff --git a/tests/integration/fixtures/uart_mock_ld2410_engineering.yaml b/tests/integration/fixtures/uart_mock_ld2410_engineering.yaml
new file mode 100644
index 0000000000..3b730fc1f8
--- /dev/null
+++ b/tests/integration/fixtures/uart_mock_ld2410_engineering.yaml
@@ -0,0 +1,156 @@
+esphome:
+  name: uart-mock-ld2410-eng-test
+
+host:
+api:
+logger:
+  level: VERBOSE
+
+external_components:
+  - source:
+      type: local
+      path: EXTERNAL_COMPONENT_PATH
+
+# Dummy uart entry to satisfy ld2410's DEPENDENCIES = ["uart"]
+uart:
+  baud_rate: 115200
+  port: /dev/null
+
+uart_mock:
+  id: mock_uart
+  baud_rate: 256000
+  injections:
+    # Phase 1 (t=100ms): Valid LD2410 engineering mode data frame
+    # Captured from a real Screek Human Presence Sensor 1U with LD2410 firmware 2.4.x
+    #
+    # Engineering mode frame layout (45 bytes):
+    #   [0-3]   F4 F3 F2 F1 = data frame header
+    #   [4-5]   23 00       = length 35
+    #   [6]     01          = data type (engineering mode)
+    #   [7]     AA          = data header marker
+    #   [8]     03          = target states (moving+still)
+    #   [9-10]  1E 00       = moving distance 30 (0x001E)
+    #   [11]    64          = moving energy 100
+    #   [12-13] 1E 00       = still distance 30 (0x001E)
+    #   [14]    64          = still energy 100
+    #   [15-16] 00 00       = detection distance 0
+    #   [17]    08          = max moving distance gate
+    #   [18]    08          = max still distance gate
+    #   [19-27] gate moving energies (gates 0-8)
+    #   [28-36] gate still energies (gates 0-8)
+    #   [37]    57          = light sensor value 87
+    #   [38]    01          = out pin presence (HIGH)
+    #   [39]    55          = data footer marker
+    #   [40]    00          = check
+    #   [41-44] F8 F7 F6 F5 = data frame footer
+    - delay: 100ms
+      inject_rx:
+        [
+          0xF4, 0xF3, 0xF2, 0xF1,
+          0x23, 0x00,
+          0x01, 0xAA,
+          0x03,
+          0x1E, 0x00,
+          0x64,
+          0x1E, 0x00,
+          0x64,
+          0x00, 0x00,
+          0x08, 0x08,
+          0x64, 0x41, 0x06, 0x0E, 0x2B, 0x16, 0x03, 0x03, 0x07,
+          0x00, 0x00, 0x64, 0x64, 0x64, 0x64, 0x64, 0x64, 0x64,
+          0x57, 0x01,
+          0x55, 0x00,
+          0xF8, 0xF7, 0xF6, 0xF5,
+        ]
+
+    # Phase 2 (t=200ms): Second engineering mode frame with different values
+    # Real capture: moving at 73cm, still at 30cm, detection at 33cm
+    - delay: 100ms
+      inject_rx:
+        [
+          0xF4, 0xF3, 0xF2, 0xF1,
+          0x23, 0x00,
+          0x01, 0xAA,
+          0x03,
+          0x49, 0x00,
+          0x64,
+          0x1E, 0x00,
+          0x64,
+          0x21, 0x00,
+          0x08, 0x08,
+          0x11, 0x64, 0x05, 0x29, 0x39, 0x10, 0x03, 0x11, 0x0E,
+          0x00, 0x00, 0x64, 0x64, 0x64, 0x64, 0x64, 0x64, 0x64,
+          0x57, 0x01,
+          0x55, 0x00,
+          0xF8, 0xF7, 0xF6, 0xF5,
+        ]
+
+    # Phase 3 (t=300ms): Frame with still target at 291cm (multi-byte distance)
+    # This tests the two_byte_to_int function with high byte > 0
+    # Note: low byte 0x2F < 0x80 so it avoids the signed char bug
+    - delay: 100ms
+      inject_rx:
+        [
+          0xF4, 0xF3, 0xF2, 0xF1,
+          0x23, 0x00,
+          0x01, 0xAA,
+          0x03,
+          0x2F, 0x00,
+          0x36,
+          0x23, 0x01,
+          0x64,
+          0x21, 0x00,
+          0x08, 0x08,
+          0x2F, 0x36, 0x09, 0x0D, 0x15, 0x0B, 0x06, 0x06, 0x08,
+          0x00, 0x00, 0x64, 0x64, 0x64, 0x64, 0x64, 0x5A, 0x3D,
+          0x57, 0x01,
+          0x55, 0x00,
+          0xF8, 0xF7, 0xF6, 0xF5,
+        ]
+
+ld2410:
+  id: ld2410_dev
+  uart_id: mock_uart
+
+sensor:
+  - platform: ld2410
+    ld2410_id: ld2410_dev
+    moving_distance:
+      name: "Moving Distance"
+    still_distance:
+      name: "Still Distance"
+    moving_energy:
+      name: "Moving Energy"
+    still_energy:
+      name: "Still Energy"
+    detection_distance:
+      name: "Detection Distance"
+    light:
+      name: "Light"
+    g0:
+      move_energy:
+        name: "Gate 0 Move Energy"
+      still_energy:
+        name: "Gate 0 Still Energy"
+    g1:
+      move_energy:
+        name: "Gate 1 Move Energy"
+      still_energy:
+        name: "Gate 1 Still Energy"
+    g2:
+      move_energy:
+        name: "Gate 2 Move Energy"
+      still_energy:
+        name: "Gate 2 Still Energy"
+
+binary_sensor:
+  - platform: ld2410
+    ld2410_id: ld2410_dev
+    has_target:
+      name: "Has Target"
+    has_moving_target:
+      name: "Has Moving Target"
+    has_still_target:
+      name: "Has Still Target"
+    out_pin_presence_status:
+      name: "Out Pin Presence"
diff --git a/tests/integration/fixtures/uart_mock_modbus.yaml b/tests/integration/fixtures/uart_mock_modbus.yaml
new file mode 100644
index 0000000000..89b9b91861
--- /dev/null
+++ b/tests/integration/fixtures/uart_mock_modbus.yaml
@@ -0,0 +1,40 @@
+esphome:
+  name: uart-mock-modbus-test
+
+host:
+api:
+logger:
+  level: VERBOSE
+
+external_components:
+  - source:
+      type: local
+      path: EXTERNAL_COMPONENT_PATH
+
+# Dummy uart entry to satisfy modbus's DEPENDENCIES = ["uart"]
+# The actual UART bus used is the uart_mock component below
+uart:
+  baud_rate: 115200
+  port: /dev/null
+
+uart_mock:
+  - id: virtual_uart_dev
+    baud_rate: 9600
+    rx_full_threshold: 120
+    rx_timeout: 2
+    debug:
+    responses:
+      - expect_tx: [0x01, 0x03, 0x00, 0x03, 0x00, 0x01, 0x74, 0x0A] # Read holding register 1 on device 1
+        inject_rx: [0x01, 0x03, 0x02, 0x01, 0x03, 0xF9, 0xD5] # Return value 0x0103 (hex) = 259 (dec)
+
+modbus:
+  uart_id: virtual_uart_dev
+
+modbus_controller:
+  address: 1
+
+sensor:
+  - platform: modbus_controller
+    name: "basic_register"
+    address: 0x03
+    register_type: holding
diff --git a/tests/integration/fixtures/uart_mock_modbus_timing.yaml b/tests/integration/fixtures/uart_mock_modbus_timing.yaml
new file mode 100644
index 0000000000..cd485ca394
--- /dev/null
+++ b/tests/integration/fixtures/uart_mock_modbus_timing.yaml
@@ -0,0 +1,54 @@
+esphome:
+  name: uart-mock-modbus-test
+
+host:
+api:
+logger:
+  level: VERBOSE
+
+external_components:
+  - source:
+      type: local
+      path: EXTERNAL_COMPONENT_PATH
+
+# Dummy uart entry to satisfy modbus's DEPENDENCIES = ["uart"]
+# The actual UART bus used is the uart_mock component below
+uart:
+  baud_rate: 115200
+  port: /dev/null
+
+uart_mock:
+  - id: virtual_uart_dev
+    baud_rate: 9600
+    rx_full_threshold: 120
+    rx_timeout: 2
+    debug:
+    on_tx:
+      - then:
+          - if:
+              condition: #Read 80 input registers on device 2, starting at address 0 (SDM meter request)
+                lambda: "return data == std::vector<uint8_t>({0x02,0x04,0x00,0x00,0x00,0x50,0xF0,0x05});"
+              then:
+                - uart_mock.inject_rx: # Good response from SDM meter with CRC. Voltage is 243V
+                    !lambda return {0x02,0x04,0xA0,0x43,0x73,0x19,0x9A,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+                    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+                    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+                    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x3F,0x80,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+                    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+                    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+                    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00};
+                - delay: 120ms # Simulate some delay for UART buffer to fill before next part of response (1ms = 1 byte at 9600 baud)
+                - uart_mock.inject_rx: # Rest of response (including CRC)
+                    !lambda return{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+                    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x42,0x6F,0xCC,0xCD,0x43,0x7C,0xB8,0x10,0x3D,0x38,0x51,0xEC,
+                    0x43,0x81,0x1B,0xE7,0x3B,0x03,0x12,0x6F,0x50,0x1B};
+
+modbus:
+  uart_id: virtual_uart_dev
+
+sensor:
+  - platform: sdm_meter
+    address: 2
+    phase_a:
+      voltage:
+        name: sdm_voltage
diff --git a/tests/integration/test_uart_mock_ld2410.py b/tests/integration/test_uart_mock_ld2410.py
new file mode 100644
index 0000000000..e01d6ff8e8
--- /dev/null
+++ b/tests/integration/test_uart_mock_ld2410.py
@@ -0,0 +1,392 @@
+"""Integration test for LD2410 component with mock UART.
+
+Tests:
+test_uart_mock_ld2410 (normal mode):
+  1. Happy path - valid data frame publishes correct sensor values
+  2. Garbage resilience - random bytes don't crash the component
+  3. Truncated frame handling - partial frame doesn't corrupt state
+  4. Buffer overflow recovery - overflow resets the parser
+  5. Post-overflow parsing - next valid frame after overflow is parsed correctly
+  6. TX logging - verifies LD2410 sends expected setup commands
+
+test_uart_mock_ld2410_engineering (engineering mode):
+  1. Engineering mode frames with per-gate energy data and light sensor
+  2. Multi-byte still distance (291cm) using high byte > 0
+  3. Out pin presence binary sensor
+  4. Gate energy sensor values from real device captures
+"""
+
+from __future__ import annotations
+
+import asyncio
+from pathlib import Path
+
+from aioesphomeapi import (
+    BinarySensorInfo,
+    BinarySensorState,
+    EntityState,
+    SensorInfo,
+    SensorState,
+)
+import pytest
+
+from .state_utils import InitialStateHelper, build_key_to_entity_mapping, find_entity
+from .types import APIClientConnectedFactory, RunCompiledFunction
+
+
+@pytest.mark.asyncio
+async def test_uart_mock_ld2410(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test LD2410 data parsing with happy path, garbage, overflow, and recovery."""
+    # Replace external component path placeholder
+    external_components_path = str(
+        Path(__file__).parent / "fixtures" / "external_components"
+    )
+    yaml_config = yaml_config.replace(
+        "EXTERNAL_COMPONENT_PATH", external_components_path
+    )
+
+    loop = asyncio.get_running_loop()
+
+    # Track overflow warning in logs
+    overflow_seen = loop.create_future()
+
+    # Track TX data logged by the mock for assertions
+    tx_log_lines: list[str] = []
+
+    def line_callback(line: str) -> None:
+        if "Max command length exceeded" in line and not overflow_seen.done():
+            overflow_seen.set_result(True)
+        # Capture all TX log lines from uart_mock
+        if "uart_mock" in line and "TX " in line:
+            tx_log_lines.append(line)
+
+    # Track sensor state updates (after initial state is swallowed)
+    sensor_states: dict[str, list[float]] = {
+        "moving_distance": [],
+        "still_distance": [],
+        "moving_energy": [],
+        "still_energy": [],
+        "detection_distance": [],
+    }
+    binary_states: dict[str, list[bool]] = {
+        "has_target": [],
+        "has_moving_target": [],
+        "has_still_target": [],
+    }
+
+    # Signal when we see recovery frame values
+    recovery_received = loop.create_future()
+
+    def on_state(state: EntityState) -> None:
+        if isinstance(state, SensorState) and not state.missing_state:
+            sensor_name = key_to_sensor.get(state.key)
+            if sensor_name and sensor_name in sensor_states:
+                sensor_states[sensor_name].append(state.state)
+                # Check if this is the recovery frame (moving_distance = 50)
+                if (
+                    sensor_name == "moving_distance"
+                    and state.state == pytest.approx(50.0)
+                    and not recovery_received.done()
+                ):
+                    recovery_received.set_result(True)
+        elif isinstance(state, BinarySensorState):
+            sensor_name = key_to_sensor.get(state.key)
+            if sensor_name and sensor_name in binary_states:
+                binary_states[sensor_name].append(state.state)
+
+    async with (
+        run_compiled(yaml_config, line_callback=line_callback),
+        api_client_connected() as client,
+    ):
+        entities, _ = await client.list_entities_services()
+
+        # Build key mappings for all sensor types
+        all_names = list(sensor_states.keys()) + list(binary_states.keys())
+        key_to_sensor = build_key_to_entity_mapping(entities, all_names)
+
+        # Set up initial state helper
+        initial_state_helper = InitialStateHelper(entities)
+        client.subscribe_states(initial_state_helper.on_state_wrapper(on_state))
+
+        try:
+            await initial_state_helper.wait_for_initial_states()
+        except TimeoutError:
+            pytest.fail("Timeout waiting for initial states")
+
+        # Phase 1 values are in the initial states (swallowed by InitialStateHelper).
+        # Verify them via initial_states dict.
+        moving_dist_entity = find_entity(entities, "moving_distance", SensorInfo)
+        assert moving_dist_entity is not None
+        initial_moving = initial_state_helper.initial_states.get(moving_dist_entity.key)
+        assert initial_moving is not None and isinstance(initial_moving, SensorState)
+        assert initial_moving.state == pytest.approx(100.0), (
+            f"Initial moving distance should be 100, got {initial_moving.state}"
+        )
+
+        still_dist_entity = find_entity(entities, "still_distance", SensorInfo)
+        assert still_dist_entity is not None
+        initial_still = initial_state_helper.initial_states.get(still_dist_entity.key)
+        assert initial_still is not None and isinstance(initial_still, SensorState)
+        assert initial_still.state == pytest.approx(120.0), (
+            f"Initial still distance should be 120, got {initial_still.state}"
+        )
+
+        moving_energy_entity = find_entity(entities, "moving_energy", SensorInfo)
+        assert moving_energy_entity is not None
+        initial_me = initial_state_helper.initial_states.get(moving_energy_entity.key)
+        assert initial_me is not None and isinstance(initial_me, SensorState)
+        assert initial_me.state == pytest.approx(50.0), (
+            f"Initial moving energy should be 50, got {initial_me.state}"
+        )
+
+        still_energy_entity = find_entity(entities, "still_energy", SensorInfo)
+        assert still_energy_entity is not None
+        initial_se = initial_state_helper.initial_states.get(still_energy_entity.key)
+        assert initial_se is not None and isinstance(initial_se, SensorState)
+        assert initial_se.state == pytest.approx(25.0), (
+            f"Initial still energy should be 25, got {initial_se.state}"
+        )
+
+        detect_dist_entity = find_entity(entities, "detection_distance", SensorInfo)
+        assert detect_dist_entity is not None
+        initial_dd = initial_state_helper.initial_states.get(detect_dist_entity.key)
+        assert initial_dd is not None and isinstance(initial_dd, SensorState)
+        assert initial_dd.state == pytest.approx(300.0), (
+            f"Initial detection distance should be 300, got {initial_dd.state}"
+        )
+
+        # Wait for the recovery frame (Phase 5) to be parsed
+        # This proves the component survived garbage + truncated + overflow
+        try:
+            await asyncio.wait_for(recovery_received, timeout=15.0)
+        except TimeoutError:
+            pytest.fail(
+                f"Timeout waiting for recovery frame. Received sensor states:\n"
+                f"  moving_distance: {sensor_states['moving_distance']}\n"
+                f"  still_distance: {sensor_states['still_distance']}\n"
+                f"  moving_energy: {sensor_states['moving_energy']}\n"
+                f"  still_energy: {sensor_states['still_energy']}\n"
+                f"  detection_distance: {sensor_states['detection_distance']}"
+            )
+
+        # Verify overflow warning was logged
+        assert overflow_seen.done(), (
+            "Expected 'Max command length exceeded' warning in logs"
+        )
+
+        # Verify LD2410 sent setup commands (TX logging)
+        # LD2410 sends 7 commands during setup: FF (config on), A0 (version),
+        # A5 (MAC), AB (distance res), AE (light), 61 (params), FE (config off)
+        assert len(tx_log_lines) > 0, "Expected TX log lines from uart_mock"
+        tx_data = " ".join(tx_log_lines)
+        # Verify command frame header appears (FD:FC:FB:FA)
+        assert "FD:FC:FB:FA" in tx_data, (
+            "Expected LD2410 command frame header FD:FC:FB:FA in TX log"
+        )
+        # Verify command frame footer appears (04:03:02:01)
+        assert "04:03:02:01" in tx_data, (
+            "Expected LD2410 command frame footer 04:03:02:01 in TX log"
+        )
+
+        # Recovery frame values (Phase 5, after overflow)
+        assert len(sensor_states["moving_distance"]) >= 1, (
+            f"Expected recovery moving_distance, got: {sensor_states['moving_distance']}"
+        )
+        # Find the recovery value (moving_distance = 50)
+        recovery_values = [
+            v for v in sensor_states["moving_distance"] if v == pytest.approx(50.0)
+        ]
+        assert len(recovery_values) >= 1, (
+            f"Expected moving_distance=50 in recovery, got: {sensor_states['moving_distance']}"
+        )
+
+        # Recovery frame: moving=50, still=75, energy=100/80, detect=127
+        recovery_idx = next(
+            i
+            for i, v in enumerate(sensor_states["moving_distance"])
+            if v == pytest.approx(50.0)
+        )
+        assert sensor_states["still_distance"][recovery_idx] == pytest.approx(75.0), (
+            f"Recovery still distance should be 75, got {sensor_states['still_distance'][recovery_idx]}"
+        )
+        assert sensor_states["moving_energy"][recovery_idx] == pytest.approx(100.0), (
+            f"Recovery moving energy should be 100, got {sensor_states['moving_energy'][recovery_idx]}"
+        )
+        assert sensor_states["still_energy"][recovery_idx] == pytest.approx(80.0), (
+            f"Recovery still energy should be 80, got {sensor_states['still_energy'][recovery_idx]}"
+        )
+        assert sensor_states["detection_distance"][recovery_idx] == pytest.approx(
+            127.0
+        ), (
+            f"Recovery detection distance should be 127, got {sensor_states['detection_distance'][recovery_idx]}"
+        )
+
+        # Verify binary sensors detected targets
+        # Binary sensors could be in initial states or forwarded states
+        has_target_entity = find_entity(entities, "has_target", BinarySensorInfo)
+        assert has_target_entity is not None
+        initial_ht = initial_state_helper.initial_states.get(has_target_entity.key)
+        assert initial_ht is not None and isinstance(initial_ht, BinarySensorState)
+        assert initial_ht.state is True, "Has target should be True"
+
+        has_moving_entity = find_entity(entities, "has_moving_target", BinarySensorInfo)
+        assert has_moving_entity is not None
+        initial_hm = initial_state_helper.initial_states.get(has_moving_entity.key)
+        assert initial_hm is not None and isinstance(initial_hm, BinarySensorState)
+        assert initial_hm.state is True, "Has moving target should be True"
+
+        has_still_entity = find_entity(entities, "has_still_target", BinarySensorInfo)
+        assert has_still_entity is not None
+        initial_hs = initial_state_helper.initial_states.get(has_still_entity.key)
+        assert initial_hs is not None and isinstance(initial_hs, BinarySensorState)
+        assert initial_hs.state is True, "Has still target should be True"
+
+
+@pytest.mark.asyncio
+async def test_uart_mock_ld2410_engineering(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test LD2410 engineering mode with per-gate energy, light, and multi-byte distance."""
+    external_components_path = str(
+        Path(__file__).parent / "fixtures" / "external_components"
+    )
+    yaml_config = yaml_config.replace(
+        "EXTERNAL_COMPONENT_PATH", external_components_path
+    )
+
+    loop = asyncio.get_running_loop()
+
+    # Track sensor state updates (after initial state is swallowed)
+    sensor_states: dict[str, list[float]] = {
+        "moving_distance": [],
+        "still_distance": [],
+        "moving_energy": [],
+        "still_energy": [],
+        "detection_distance": [],
+        "light": [],
+        "gate_0_move_energy": [],
+        "gate_1_move_energy": [],
+        "gate_2_move_energy": [],
+        "gate_0_still_energy": [],
+        "gate_1_still_energy": [],
+        "gate_2_still_energy": [],
+    }
+    binary_states: dict[str, list[bool]] = {
+        "has_target": [],
+        "has_moving_target": [],
+        "has_still_target": [],
+        "out_pin_presence": [],
+    }
+
+    # Signal when we see Phase 3 frame (still_distance = 291)
+    phase3_received = loop.create_future()
+
+    def on_state(state: EntityState) -> None:
+        if isinstance(state, SensorState) and not state.missing_state:
+            sensor_name = key_to_sensor.get(state.key)
+            if sensor_name and sensor_name in sensor_states:
+                sensor_states[sensor_name].append(state.state)
+                if (
+                    sensor_name == "still_distance"
+                    and state.state == pytest.approx(291.0)
+                    and not phase3_received.done()
+                ):
+                    phase3_received.set_result(True)
+        elif isinstance(state, BinarySensorState):
+            sensor_name = key_to_sensor.get(state.key)
+            if sensor_name and sensor_name in binary_states:
+                binary_states[sensor_name].append(state.state)
+
+    async with (
+        run_compiled(yaml_config),
+        api_client_connected() as client,
+    ):
+        entities, _ = await client.list_entities_services()
+
+        all_names = list(sensor_states.keys()) + list(binary_states.keys())
+        key_to_sensor = build_key_to_entity_mapping(entities, all_names)
+
+        initial_state_helper = InitialStateHelper(entities)
+        client.subscribe_states(initial_state_helper.on_state_wrapper(on_state))
+
+        try:
+            await initial_state_helper.wait_for_initial_states()
+        except TimeoutError:
+            pytest.fail("Timeout waiting for initial states")
+
+        # Phase 1 initial values (engineering mode frame):
+        # moving=30, energy=100, still=30, energy=100, detect=0
+        moving_dist_entity = find_entity(entities, "moving_distance", SensorInfo)
+        assert moving_dist_entity is not None
+        initial_moving = initial_state_helper.initial_states.get(moving_dist_entity.key)
+        assert initial_moving is not None and isinstance(initial_moving, SensorState)
+        assert initial_moving.state == pytest.approx(30.0), (
+            f"Initial moving distance should be 30, got {initial_moving.state}"
+        )
+
+        still_dist_entity = find_entity(entities, "still_distance", SensorInfo)
+        assert still_dist_entity is not None
+        initial_still = initial_state_helper.initial_states.get(still_dist_entity.key)
+        assert initial_still is not None and isinstance(initial_still, SensorState)
+        assert initial_still.state == pytest.approx(30.0), (
+            f"Initial still distance should be 30, got {initial_still.state}"
+        )
+
+        # Verify engineering mode sensors from initial state
+        # Gate 0 moving energy = 0x64 = 100
+        gate0_move_entity = find_entity(entities, "gate_0_move_energy", SensorInfo)
+        assert gate0_move_entity is not None
+        initial_g0m = initial_state_helper.initial_states.get(gate0_move_entity.key)
+        assert initial_g0m is not None and isinstance(initial_g0m, SensorState)
+        assert initial_g0m.state == pytest.approx(100.0), (
+            f"Gate 0 move energy should be 100, got {initial_g0m.state}"
+        )
+
+        # Gate 1 moving energy = 0x41 = 65
+        gate1_move_entity = find_entity(entities, "gate_1_move_energy", SensorInfo)
+        assert gate1_move_entity is not None
+        initial_g1m = initial_state_helper.initial_states.get(gate1_move_entity.key)
+        assert initial_g1m is not None and isinstance(initial_g1m, SensorState)
+        assert initial_g1m.state == pytest.approx(65.0), (
+            f"Gate 1 move energy should be 65, got {initial_g1m.state}"
+        )
+
+        # Light sensor = 0x57 = 87
+        light_entity = find_entity(entities, "light", SensorInfo)
+        assert light_entity is not None
+        initial_light = initial_state_helper.initial_states.get(light_entity.key)
+        assert initial_light is not None and isinstance(initial_light, SensorState)
+        assert initial_light.state == pytest.approx(87.0), (
+            f"Light sensor should be 87, got {initial_light.state}"
+        )
+
+        # Out pin presence = 0x01 = True
+        out_pin_entity = find_entity(entities, "out_pin_presence", BinarySensorInfo)
+        assert out_pin_entity is not None
+        initial_out = initial_state_helper.initial_states.get(out_pin_entity.key)
+        assert initial_out is not None and isinstance(initial_out, BinarySensorState)
+        assert initial_out.state is True, "Out pin presence should be True"
+
+        # Wait for Phase 3 frame (still_distance = 291cm, multi-byte)
+        try:
+            await asyncio.wait_for(phase3_received, timeout=15.0)
+        except TimeoutError:
+            pytest.fail(
+                f"Timeout waiting for Phase 3 frame. Received sensor states:\n"
+                f"  still_distance: {sensor_states['still_distance']}\n"
+                f"  moving_distance: {sensor_states['moving_distance']}"
+            )
+
+        # Phase 3: still distance = 0x0123 = 291cm (multi-byte distance test)
+        phase3_still = [
+            v for v in sensor_states["still_distance"] if v == pytest.approx(291.0)
+        ]
+        assert len(phase3_still) >= 1, (
+            f"Expected still_distance=291, got: {sensor_states['still_distance']}"
+        )
diff --git a/tests/integration/test_uart_mock_modbus.py b/tests/integration/test_uart_mock_modbus.py
new file mode 100644
index 0000000000..309cb56dc9
--- /dev/null
+++ b/tests/integration/test_uart_mock_modbus.py
@@ -0,0 +1,153 @@
+"""Integration test for modbus component with virtual UART.
+
+Tests:
+test_uart_mock_modbus :
+  1. Read a single register and parse successfully (basic_register)
+  2. Read multiple registers from SDM meter and parse successfully (sdm_voltage), with some intermediate delay to simulate UART buffer time.
+
+"""
+
+from __future__ import annotations
+
+import asyncio
+from pathlib import Path
+
+from aioesphomeapi import EntityState, SensorState
+import pytest
+
+from .state_utils import InitialStateHelper, build_key_to_entity_mapping
+from .types import APIClientConnectedFactory, RunCompiledFunction
+
+
+@pytest.mark.asyncio
+async def test_uart_mock_modbus(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test basic modbus data parsing."""
+    # Replace external component path placeholder
+    external_components_path = str(
+        Path(__file__).parent / "fixtures" / "external_components"
+    )
+    yaml_config = yaml_config.replace(
+        "EXTERNAL_COMPONENT_PATH", external_components_path
+    )
+
+    loop = asyncio.get_running_loop()
+
+    # Track sensor state updates (after initial state is swallowed)
+    sensor_states: dict[str, list[float]] = {
+        "basic_register": [],
+    }
+
+    basic_register_changed = loop.create_future()
+
+    def on_state(state: EntityState) -> None:
+        if isinstance(state, SensorState) and not state.missing_state:
+            sensor_name = key_to_sensor.get(state.key)
+            if sensor_name and sensor_name in sensor_states:
+                sensor_states[sensor_name].append(state.state)
+                if (
+                    sensor_name == "basic_register"
+                    and state.state == 259.0
+                    and not basic_register_changed.done()
+                ):
+                    basic_register_changed.set_result(True)
+
+    async with (
+        run_compiled(yaml_config),
+        api_client_connected() as client,
+    ):
+        entities, _ = await client.list_entities_services()
+
+        # Build key mappings for all sensor types
+        all_names = list(sensor_states.keys())
+        key_to_sensor = build_key_to_entity_mapping(entities, all_names)
+
+        # Set up initial state helper
+        initial_state_helper = InitialStateHelper(entities)
+        client.subscribe_states(initial_state_helper.on_state_wrapper(on_state))
+
+        try:
+            await initial_state_helper.wait_for_initial_states()
+        except TimeoutError:
+            pytest.fail("Timeout waiting for initial states")
+
+        # Wait for basic register to be updated with successful parse
+        try:
+            await asyncio.wait_for(basic_register_changed, timeout=15.0)
+        except TimeoutError:
+            pytest.fail(
+                f"Timeout waiting for Basic Register change. Received sensor states:\n"
+                f"  basic_register: {sensor_states['basic_register']}\n"
+            )
+
+
+@pytest.mark.asyncio
+@pytest.mark.xfail(
+    reason="There is a bug in UART which will timeout for long responses."
+)
+async def test_uart_mock_modbus_timing(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test basic modbus data parsing."""
+    # Replace external component path placeholder
+    external_components_path = str(
+        Path(__file__).parent / "fixtures" / "external_components"
+    )
+    yaml_config = yaml_config.replace(
+        "EXTERNAL_COMPONENT_PATH", external_components_path
+    )
+
+    loop = asyncio.get_running_loop()
+
+    # Track sensor state updates (after initial state is swallowed)
+    sensor_states: dict[str, list[float]] = {
+        "sdm_voltage": [],
+    }
+
+    voltage_changed = loop.create_future()
+
+    def on_state(state: EntityState) -> None:
+        if isinstance(state, SensorState) and not state.missing_state:
+            sensor_name = key_to_sensor.get(state.key)
+            if sensor_name and sensor_name in sensor_states:
+                sensor_states[sensor_name].append(state.state)
+                # Check if this is a good voltage reading (243V)
+                if (
+                    sensor_name == "sdm_voltage"
+                    and state.state > 200.0
+                    and not voltage_changed.done()
+                ):
+                    voltage_changed.set_result(True)
+
+    async with (
+        run_compiled(yaml_config),
+        api_client_connected() as client,
+    ):
+        entities, _ = await client.list_entities_services()
+
+        # Build key mappings for all sensor types
+        all_names = list(sensor_states.keys())
+        key_to_sensor = build_key_to_entity_mapping(entities, all_names)
+
+        # Set up initial state helper
+        initial_state_helper = InitialStateHelper(entities)
+        client.subscribe_states(initial_state_helper.on_state_wrapper(on_state))
+
+        try:
+            await initial_state_helper.wait_for_initial_states()
+        except TimeoutError:
+            pytest.fail("Timeout waiting for initial states")
+
+        # Wait for voltage to be updated with successful parse
+        try:
+            await asyncio.wait_for(voltage_changed, timeout=15.0)
+        except TimeoutError:
+            pytest.fail(
+                f"Timeout waiting for SDM voltage change. Received sensor states:\n"
+                f"  sdm_voltage: {sensor_states['sdm_voltage']}\n"
+            )
diff --git a/tests/unit_tests/test_automation.py b/tests/unit_tests/test_automation.py
new file mode 100644
index 0000000000..61fef8201d
--- /dev/null
+++ b/tests/unit_tests/test_automation.py
@@ -0,0 +1,177 @@
+"""Tests for esphome.automation module."""
+
+from collections.abc import Generator
+from unittest.mock import patch
+
+import pytest
+
+from esphome.automation import has_non_synchronous_actions
+from esphome.util import RegistryEntry
+
+
+def _make_registry(non_synchronous_actions: set[str]) -> dict[str, RegistryEntry]:
+    """Create a mock ACTION_REGISTRY with specified non-synchronous actions.
+
+    Uses the default synchronous=False, matching the real registry behavior.
+    """
+    registry: dict[str, RegistryEntry] = {}
+    for name in non_synchronous_actions:
+        registry[name] = RegistryEntry(name, lambda: None, None, None)
+    return registry
+
+
+@pytest.fixture
+def mock_registry() -> Generator[dict[str, RegistryEntry]]:
+    """Fixture that patches ACTION_REGISTRY with delay, wait_until, script.wait as non-synchronous."""
+    registry: dict[str, RegistryEntry] = _make_registry(
+        {"delay", "wait_until", "script.wait"}
+    )
+    registry["logger.log"] = RegistryEntry(
+        "logger.log", lambda: None, None, None, synchronous=True
+    )
+    with patch("esphome.automation.ACTION_REGISTRY", registry):
+        yield registry
+
+
+def test_has_non_synchronous_actions_empty_list(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    assert has_non_synchronous_actions([]) is False
+
+
+def test_has_non_synchronous_actions_empty_dict(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    assert has_non_synchronous_actions({}) is False
+
+
+def test_has_non_synchronous_actions_non_dict_non_list(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    assert has_non_synchronous_actions("string") is False
+    assert has_non_synchronous_actions(42) is False
+    assert has_non_synchronous_actions(None) is False
+
+
+def test_has_non_synchronous_actions_delay(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    assert has_non_synchronous_actions([{"delay": "1s"}]) is True
+
+
+def test_has_non_synchronous_actions_wait_until(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    assert has_non_synchronous_actions([{"wait_until": {"condition": {}}}]) is True
+
+
+def test_has_non_synchronous_actions_script_wait(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    assert has_non_synchronous_actions([{"script.wait": "script_id"}]) is True
+
+
+def test_has_non_synchronous_actions_synchronous(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    assert has_non_synchronous_actions([{"logger.log": "hello"}]) is False
+
+
+def test_has_non_synchronous_actions_unknown_not_in_registry(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    """Unknown actions not in registry are not flagged (only registered actions count)."""
+    assert has_non_synchronous_actions([{"unknown.action": "value"}]) is False
+
+
+def test_has_non_synchronous_actions_default_non_synchronous(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    """Actions registered without explicit synchronous=True default to non-synchronous."""
+    mock_registry["some.action"] = RegistryEntry(
+        "some.action", lambda: None, None, None
+    )
+    assert has_non_synchronous_actions([{"some.action": "value"}]) is True
+
+
+def test_has_non_synchronous_actions_nested_in_then(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    """Non-synchronous action nested inside a synchronous action's then block."""
+    actions: list[dict[str, object]] = [
+        {
+            "logger.log": "first",
+            "then": [{"delay": "1s"}],
+        }
+    ]
+    assert has_non_synchronous_actions(actions) is True
+
+
+def test_has_non_synchronous_actions_deeply_nested(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    """Non-synchronous action deeply nested in action structure."""
+    actions: list[dict[str, object]] = [
+        {
+            "if": {
+                "then": [
+                    {"logger.log": "hello"},
+                    {"delay": "500ms"},
+                ]
+            }
+        }
+    ]
+    assert has_non_synchronous_actions(actions) is True
+
+
+def test_has_non_synchronous_actions_none_in_nested(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    """No non-synchronous actions even with nesting."""
+    actions: list[dict[str, object]] = [
+        {
+            "if": {
+                "then": [
+                    {"logger.log": "hello"},
+                ]
+            }
+        }
+    ]
+    assert has_non_synchronous_actions(actions) is False
+
+
+def test_has_non_synchronous_actions_multiple_one_non_synchronous(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    assert (
+        has_non_synchronous_actions(
+            [
+                {"logger.log": "first"},
+                {"delay": "1s"},
+                {"logger.log": "second"},
+            ]
+        )
+        is True
+    )
+
+
+def test_has_non_synchronous_actions_multiple_all_synchronous(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    assert (
+        has_non_synchronous_actions(
+            [
+                {"logger.log": "first"},
+                {"logger.log": "second"},
+            ]
+        )
+        is False
+    )
+
+
+def test_has_non_synchronous_actions_dict_input(
+    mock_registry: dict[str, RegistryEntry],
+) -> None:
+    """Direct dict input (single action)."""
+    assert has_non_synchronous_actions({"delay": "1s"}) is True
+    assert has_non_synchronous_actions({"logger.log": "hello"}) is False
diff --git a/tests/unit_tests/test_cpp_generator.py b/tests/unit_tests/test_cpp_generator.py
index 049d21027f..bdc31cdef8 100644
--- a/tests/unit_tests/test_cpp_generator.py
+++ b/tests/unit_tests/test_cpp_generator.py
@@ -248,6 +248,12 @@ class TestLiterals:
             (cg.FloatLiteral(4.2), "4.2f"),
             (cg.FloatLiteral(1.23456789), "1.23456789f"),
             (cg.FloatLiteral(math.nan), "NAN"),
+            (cg.FlashStringLiteral("hello"), 'ESPHOME_F("hello")'),
+            (cg.FlashStringLiteral(""), 'ESPHOME_F("")'),
+            (
+                cg.FlashStringLiteral('quote"here'),
+                'ESPHOME_F("quote\\042here")',
+            ),
         ),
     )
     def test_str__simple(self, target: cg.Literal, expected: str):
@@ -624,3 +630,75 @@ class TestProcessLambda:
         # Test invalid tuple format (single element)
         with pytest.raises(AssertionError):
             await cg.process_lambda(lambda_obj, [(int,)])
+
+
+@pytest.mark.asyncio
+async def test_templatable__string_with_std_string_returns_flash_literal() -> None:
+    """Static string with std::string output_type returns FlashStringLiteral."""
+    result = await cg.templatable("hello", [], ct.std_string)
+
+    assert isinstance(result, cg.FlashStringLiteral)
+    assert str(result) == 'ESPHOME_F("hello")'
+
+
+@pytest.mark.asyncio
+async def test_templatable__empty_string_with_std_string() -> None:
+    """Empty static string with std::string output_type returns FlashStringLiteral."""
+    result = await cg.templatable("", [], ct.std_string)
+
+    assert isinstance(result, cg.FlashStringLiteral)
+    assert str(result) == 'ESPHOME_F("")'
+
+
+@pytest.mark.asyncio
+async def test_templatable__string_with_none_output_type() -> None:
+    """Static string with output_type=None returns raw string (no wrapping)."""
+    result = await cg.templatable("hello", [], None)
+
+    assert isinstance(result, str)
+    assert result == "hello"
+
+
+@pytest.mark.asyncio
+async def test_templatable__int_with_std_string() -> None:
+    """Non-string value with std::string output_type returns raw value."""
+    result = await cg.templatable(42, [], ct.std_string)
+
+    assert result == 42
+
+
+@pytest.mark.asyncio
+async def test_templatable__string_with_non_string_output_type() -> None:
+    """Static string with non-std::string output_type returns raw string."""
+    result = await cg.templatable("hello", [], ct.bool_)
+
+    assert isinstance(result, str)
+    assert result == "hello"
+
+
+@pytest.mark.asyncio
+async def test_templatable__with_to_exp_callable() -> None:
+    """When to_exp is provided, it is applied to non-template values."""
+    result = await cg.templatable(42, [], None, to_exp=lambda x: x * 2)
+
+    assert result == 84
+
+
+@pytest.mark.asyncio
+async def test_templatable__with_to_exp_dict() -> None:
+    """When to_exp is a dict, value is looked up."""
+    mapping: dict[str, int] = {"on": 1, "off": 0}
+    result = await cg.templatable("on", [], None, to_exp=mapping)
+
+    assert result == 1
+
+
+@pytest.mark.asyncio
+async def test_templatable__lambda_with_std_string() -> None:
+    """Lambda value returns LambdaExpression, not FlashStringLiteral."""
+    from esphome.core import Lambda
+
+    lambda_obj = Lambda('return "hello";')
+    result = await cg.templatable(lambda_obj, [], ct.std_string)
+
+    assert isinstance(result, cg.LambdaExpression)
diff --git a/tests/unit_tests/test_cpp_helpers.py b/tests/unit_tests/test_cpp_helpers.py
index 82ded409c7..5b6eed156f 100644
--- a/tests/unit_tests/test_cpp_helpers.py
+++ b/tests/unit_tests/test_cpp_helpers.py
@@ -14,7 +14,11 @@ async def test_gpio_pin_expression__conf_is_none(monkeypatch):
 
 @pytest.mark.asyncio
 async def test_register_component(monkeypatch):
-    var = Mock(base="foo.bar")
+    base_mock = Mock()
+    base_mock.__str__ = lambda self: "foo.bar"
+    base_mock.type = Mock()
+    base_mock.type.__str__ = lambda self: "foo::Bar"
+    var = Mock(base=base_mock)
 
     app_mock = Mock(register_component_=Mock(return_value=var))
     monkeypatch.setattr(ch, "App", app_mock)
@@ -46,7 +50,11 @@ async def test_register_component__no_component_id(monkeypatch):
 
 @pytest.mark.asyncio
 async def test_register_component__with_setup_priority(monkeypatch):
-    var = Mock(base="foo.bar")
+    base_mock = Mock()
+    base_mock.__str__ = lambda self: "foo.bar"
+    base_mock.type = Mock()
+    base_mock.type.__str__ = lambda self: "foo::Bar"
+    var = Mock(base=base_mock)
 
     app_mock = Mock(register_component_=Mock(return_value=var))
     monkeypatch.setattr(ch, "App", app_mock)
diff --git a/tests/unit_tests/test_external_files.py b/tests/unit_tests/test_external_files.py
index 05e0bd3523..a319fae83d 100644
--- a/tests/unit_tests/test_external_files.py
+++ b/tests/unit_tests/test_external_files.py
@@ -144,16 +144,16 @@ def test_has_remote_file_changed_no_local_file(setup_core: Path) -> None:
 def test_has_remote_file_changed_network_error(
     mock_head: MagicMock, setup_core: Path
 ) -> None:
-    """Test has_remote_file_changed handles network errors gracefully."""
+    """Test has_remote_file_changed returns False on network error when file is cached."""
     test_file = setup_core / "cached.txt"
     test_file.write_text("cached content")
 
     mock_head.side_effect = requests.exceptions.RequestException("Network error")
 
     url = "https://example.com/file.txt"
+    result = external_files.has_remote_file_changed(url, test_file)
 
-    with pytest.raises(Invalid, match="Could not check if.*Network error"):
-        external_files.has_remote_file_changed(url, test_file)
+    assert result is False
 
 
 @patch("esphome.external_files.requests.head")
@@ -198,3 +198,41 @@ def test_is_file_recent_handles_float_seconds(setup_core: Path) -> None:
     result = external_files.is_file_recent(test_file, refresh)
 
     assert result is True
+
+
+@patch("esphome.external_files.requests.get")
+@patch("esphome.external_files.has_remote_file_changed")
+def test_download_content_with_network_error_uses_cache(
+    mock_has_changed: MagicMock, mock_get: MagicMock, setup_core: Path
+) -> None:
+    """Test download_content uses cached file when network fails."""
+    test_file = setup_core / "cached.txt"
+    cached_content = b"cached content"
+    test_file.write_bytes(cached_content)
+
+    # Simulate file has changed, so it tries to download
+    mock_has_changed.return_value = True
+    mock_get.side_effect = requests.exceptions.RequestException("Network error")
+
+    url = "https://example.com/file.txt"
+    result = external_files.download_content(url, test_file)
+
+    assert result == cached_content
+
+
+@patch("esphome.external_files.requests.get")
+@patch("esphome.external_files.has_remote_file_changed")
+def test_download_content_with_network_error_no_cache_fails(
+    mock_has_changed: MagicMock, mock_get: MagicMock, setup_core: Path
+) -> None:
+    """Test download_content raises error when network fails and no cache exists."""
+    test_file = setup_core / "nonexistent.txt"
+
+    # Simulate file has changed (doesn't exist), so it tries to download
+    mock_has_changed.return_value = True
+    mock_get.side_effect = requests.exceptions.RequestException("Network error")
+
+    url = "https://example.com/file.txt"
+
+    with pytest.raises(Invalid, match="Could not download from.*Network error"):
+        external_files.download_content(url, test_file)