From 19bbd39e334332d5ebc3f33a2a435e96ab54555f Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sat, 28 Feb 2026 17:06:46 -1000
Subject: [PATCH 01/10] [uart] Enable wake-on-RX by default on ESP32 (#14391)

---
 esphome/components/uart/__init__.py        | 42 +++++-----------------
 esphome/components/zwave_proxy/__init__.py |  3 --
 2 files changed, 8 insertions(+), 37 deletions(-)

diff --git a/esphome/components/uart/__init__.py b/esphome/components/uart/__init__.py
index a6f4cf5d5f..69db4b44aa 100644
--- a/esphome/components/uart/__init__.py
+++ b/esphome/components/uart/__init__.py
@@ -1,4 +1,3 @@
-from dataclasses import dataclass
 from logging import getLogger
 import math
 import re
@@ -117,38 +116,6 @@ MULTI_CONF = True
 MULTI_CONF_NO_DEFAULT = True
 
 
-@dataclass
-class UARTData:
-    """State data for UART component configuration generation."""
-
-    wake_loop_on_rx: bool = False
-
-
-def _get_data() -> UARTData:
-    """Get UART component data from CORE.data."""
-    if DOMAIN not in CORE.data:
-        CORE.data[DOMAIN] = UARTData()
-    return CORE.data[DOMAIN]
-
-
-def request_wake_loop_on_rx() -> None:
-    """Request that the UART wake the main loop when data is received.
-
-    Components that need low-latency notification of incoming UART data
-    should call this function during their code generation.
-    This enables the RX event task which wakes the main loop when data arrives.
-    """
-    data = _get_data()
-    if not data.wake_loop_on_rx:
-        data.wake_loop_on_rx = True
-
-        # UART RX event task uses wake_loop_threadsafe() to notify the main loop
-        # Automatically enable the socket wake infrastructure when RX wake is requested
-        from esphome.components import socket
-
-        socket.require_wake_loop_threadsafe()
-
-
 def validate_raw_data(value):
     if isinstance(value, str):
         return value.encode("utf-8")
@@ -542,7 +509,14 @@ async def uart_write_to_code(config, action_id, template_arg, args):
 @coroutine_with_priority(CoroPriority.FINAL)
 async def final_step():
     """Final code generation step to configure optional UART features."""
-    if _get_data().wake_loop_on_rx:
+    if CORE.is_esp32 and CORE.has_networking:
+        # Wake-on-RX is essentially free on ESP32 (just an ISR function pointer
+        # registration) — enable by default to reduce RX buffer overflow risk
+        # by waking the main loop immediately when data arrives.
+        # Requires networking for the wake_loop_isrsafe() infrastructure.
+        from esphome.components import socket
+
+        socket.require_wake_loop_threadsafe()
         cg.add_define("USE_UART_WAKE_LOOP_ON_RX")
 
 
diff --git a/esphome/components/zwave_proxy/__init__.py b/esphome/components/zwave_proxy/__init__.py
index 5be05bb464..d88f9f7041 100644
--- a/esphome/components/zwave_proxy/__init__.py
+++ b/esphome/components/zwave_proxy/__init__.py
@@ -41,6 +41,3 @@ async def to_code(config):
     await cg.register_component(var, config)
     await uart.register_uart_device(var, config)
     cg.add_define("USE_ZWAVE_PROXY")
-
-    # Request UART to wake the main loop when data arrives for low-latency processing
-    uart.request_wake_loop_on_rx()

From a1760a198047d92a36fe9c8af01ca5c86f736d80 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 1 Mar 2026 10:23:10 -1000
Subject: [PATCH 02/10] [improv_serial] Add missing USE_IMPROV_SERIAL define to
 fix WiFi scan filtering (#14359)

---
 esphome/components/improv_serial/__init__.py         | 1 +
 esphome/components/wifi/wifi_component.cpp           | 2 +-
 esphome/components/wifi/wifi_component.h             | 4 ++--
 esphome/components/wifi/wifi_component_esp8266.cpp   | 2 +-
 esphome/components/wifi/wifi_component_esp_idf.cpp   | 2 +-
 esphome/components/wifi/wifi_component_libretiny.cpp | 2 +-
 esphome/components/wifi/wifi_component_pico_w.cpp    | 2 +-
 esphome/core/defines.h                               | 1 +
 8 files changed, 9 insertions(+), 7 deletions(-)

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/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/core/defines.h b/esphome/core/defines.h
index 5c982c94b1..181425c162 100644
--- a/esphome/core/defines.h
+++ b/esphome/core/defines.h
@@ -55,6 +55,7 @@
 #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

From 48b5cae6c4692c6f563b1c250aa266e31b0b1b98 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 1 Mar 2026 11:32:44 -1000
Subject: [PATCH 03/10] [api] Use StringRef for user service string arguments
 (#13974)

---
 esphome/automation.py                         |  57 +++++-
 esphome/components/api/__init__.py            |  15 +-
 esphome/components/api/api_connection.cpp     |  43 +++--
 esphome/components/api/api_frame_helper.h     |   4 +
 .../components/api/api_frame_helper_noise.cpp |  30 ++-
 .../api/api_frame_helper_plaintext.cpp        |   7 +-
 esphome/components/api/user_services.cpp      |   5 +
 esphome/components/button/__init__.py         |   4 +-
 esphome/components/cover/__init__.py          |  20 +-
 esphome/components/fan/__init__.py            |   9 +-
 esphome/components/globals/__init__.py        |   1 +
 esphome/components/light/automation.py        |  12 +-
 esphome/components/logger/__init__.py         |   4 +-
 esphome/components/mqtt/__init__.py           |   7 +-
 esphome/components/number/__init__.py         |   6 +
 esphome/components/output/__init__.py         |   7 +-
 esphome/components/script/__init__.py         |   2 +
 esphome/components/select/__init__.py         |   7 +
 esphome/components/switch/__init__.py         |  14 +-
 esphome/components/text/__init__.py           |   1 +
 esphome/core/string_ref.h                     |  14 ++
 esphome/util.py                               |  16 +-
 tests/unit_tests/test_automation.py           | 177 ++++++++++++++++++
 23 files changed, 406 insertions(+), 56 deletions(-)
 create mode 100644 tests/unit_tests/test_automation.py

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/components/api/__init__.py b/esphome/components/api/__init__.py
index 3f7cafb485..d7b6bec357 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,
@@ -604,6 +615,7 @@ 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")
@@ -644,6 +656,7 @@ 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")
diff --git a/esphome/components/api/api_connection.cpp b/esphome/components/api/api_connection.cpp
index 8b2efdde51..215af611db 100644
--- a/esphome/components/api/api_connection.cpp
+++ b/esphome/components/api/api_connection.cpp
@@ -1711,37 +1711,42 @@ 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/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/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/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/light/automation.py b/esphome/components/light/automation.py
index e5aa8fa0e9..89b2fc0fb2 100644
--- a/esphome/components/light/automation.py
+++ b/esphome/components/light/automation.py
@@ -51,6 +51,7 @@ 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])
@@ -111,13 +112,13 @@ LIGHT_TURN_ON_ACTION_SCHEMA = automation.maybe_simple_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])
@@ -193,7 +194,10 @@ 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/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/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/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/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/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/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/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/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

From 3e7424b307b5763bba217d5f0d5d18130b67be4a Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 1 Mar 2026 15:22:55 -1000
Subject: [PATCH 04/10] [preferences] Reduce heap churn with small inline
 buffer optimization (#13259)

---
 esphome/components/esp32/preferences.cpp     | 33 ++++-----
 esphome/components/libretiny/preferences.cpp | 33 ++++-----
 esphome/core/helpers.h                       | 72 ++++++++++++++++++++
 3 files changed, 96 insertions(+), 42 deletions(-)

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/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/core/helpers.h b/esphome/core/helpers.h
index b606e68df3..65d590a5e6 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:

From 0e18e4461e8d82df75b3acbb61c7dcc8c9993311 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 1 Mar 2026 16:52:53 -1000
Subject: [PATCH 05/10] [time,api] Send pre-parsed timezone struct over
 protobuf (#14233)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
---
 esphome/components/api/api.proto          | 28 ++++++++++
 esphome/components/api/api_connection.cpp | 25 ++++++++-
 esphome/components/api/api_pb2.cpp        | 54 ++++++++++++++++++
 esphome/components/api/api_pb2.h          | 38 ++++++++++++-
 esphome/components/api/api_pb2_dump.cpp   | 39 +++++++++++++
 esphome/components/time/__init__.py       | 68 +++++++++++++++++++++--
 6 files changed, 245 insertions(+), 7 deletions(-)

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 215af611db..90287ec2dd 100644
--- a/esphome/components/api/api_connection.cpp
+++ b/esphome/components/api/api_connection.cpp
@@ -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
   }
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..033b789c18 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,
@@ -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/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)
 

From 073ca63f60bb23a7c84106eb57a5ce06388b1295 Mon Sep 17 00:00:00 2001
From: Thomas Rupprecht <rupprecht.thomas@gmail.com>
Date: Mon, 2 Mar 2026 04:44:02 +0100
Subject: [PATCH 06/10] [rtttl] improve comments Part 2 (#13971)

Co-authored-by: Jonathan Swoboda <154711427+swoboda1337@users.noreply.github.com>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
---
 esphome/components/rtttl/rtttl.cpp | 189 ++++++++++++++++-------------
 esphome/components/rtttl/rtttl.h   |  31 ++---
 2 files changed, 119 insertions(+), 101 deletions(-)

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.

From 6d3d8970a67dfeed99e48e36388b319b40f3ad79 Mon Sep 17 00:00:00 2001
From: schrob <83939986+schdro@users.noreply.github.com>
Date: Mon, 2 Mar 2026 04:47:02 +0100
Subject: [PATCH 07/10] [openthread] Disable default enabled OT diag code
 (#14399)

---
 esphome/components/openthread/__init__.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/esphome/components/openthread/__init__.py b/esphome/components/openthread/__init__.py
index 89d335c574..dde4987181 100644
--- a/esphome/components/openthread/__init__.py
+++ b/esphome/components/openthread/__init__.py
@@ -53,6 +53,9 @@ 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)
 
+    # 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)
 
     if tlv := config.get(CONF_TLV):

From f68a3ed15d441a90cd96415af05cc69ad2ab5411 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 1 Mar 2026 18:09:00 -1000
Subject: [PATCH 08/10] [api] Remove virtual destructor from ProtoMessage
 (#14393)

---
 esphome/components/api/api_pb2.h    | 6 +++---
 esphome/components/api/proto.h      | 7 ++++++-
 script/api_protobuf/api_protobuf.py | 5 ++---
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/esphome/components/api/api_pb2.h b/esphome/components/api/api_pb2.h
index 033b789c18..a97f6c0a76 100644
--- a/esphome/components/api/api_pb2.h
+++ b/esphome/components/api/api_pb2.h
@@ -322,7 +322,6 @@ enum ZWaveProxyRequestType : uint32_t {
 
 class InfoResponseProtoMessage : public ProtoMessage {
  public:
-  ~InfoResponseProtoMessage() override = default;
   StringRef object_id{};
   uint32_t key{0};
   StringRef name{};
@@ -336,28 +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:
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/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"

From 80a2acca4f576b5c43fa0a87b5752a68e1d85b6c Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 1 Mar 2026 18:19:32 -1000
Subject: [PATCH 09/10] [ld2410] Add UART mock integration test for LD2410
 component (#14377)

---
 .../external_components/uart_mock/__init__.py |  86 ++++
 .../uart_mock/uart_mock.cpp                   | 159 +++++++
 .../external_components/uart_mock/uart_mock.h |  78 ++++
 .../fixtures/uart_mock_ld2410.yaml            | 145 +++++++
 .../uart_mock_ld2410_engineering.yaml         | 156 +++++++
 tests/integration/test_uart_mock_ld2410.py    | 392 ++++++++++++++++++
 6 files changed, 1016 insertions(+)
 create mode 100644 tests/integration/fixtures/external_components/uart_mock/__init__.py
 create mode 100644 tests/integration/fixtures/external_components/uart_mock/uart_mock.cpp
 create mode 100644 tests/integration/fixtures/external_components/uart_mock/uart_mock.h
 create mode 100644 tests/integration/fixtures/uart_mock_ld2410.yaml
 create mode 100644 tests/integration/fixtures/uart_mock_ld2410_engineering.yaml
 create mode 100644 tests/integration/test_uart_mock_ld2410.py

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..5bd879ab12
--- /dev/null
+++ b/tests/integration/fixtures/external_components/uart_mock/__init__.py
@@ -0,0 +1,86 @@
+import esphome.codegen as cg
+from esphome.components import uart
+from esphome.components.uart import CONF_DATA_BITS, CONF_PARITY, CONF_STOP_BITS
+import esphome.config_validation as cv
+from esphome.const import CONF_BAUD_RATE, CONF_DATA, CONF_DELAY, CONF_ID, CONF_INTERVAL
+
+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
+)
+
+CONF_INJECTIONS = "injections"
+CONF_RESPONSES = "responses"
+CONF_INJECT_RX = "inject_rx"
+CONF_EXPECT_TX = "expect_tx"
+CONF_PERIODIC_RX = "periodic_rx"
+
+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,
+    }
+)
+
+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_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),
+    }
+).extend(cv.COMPONENT_SCHEMA)
+
+
+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_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))
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..a49d51ba10
--- /dev/null
+++ b/tests/integration/fixtures/external_components/uart_mock/uart_mock.cpp
@@ -0,0 +1,159 @@
+// 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_();
+}
+
+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::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 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..00f4bf2e2b
--- /dev/null
+++ b/tests/integration/fixtures/external_components/uart_mock/uart_mock.h
@@ -0,0 +1,78 @@
+#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;
+
+  // 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);
+
+ protected:
+  void check_logger_conflict() override {}
+  void try_match_response_();
+  void inject_to_rx_buffer_(const std::vector<uint8_t> &data);
+
+  // 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};
+};
+
+}  // 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/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']}"
+        )

From 9d4357c619ee94ae9a934276525e1bfa0ac99b8b Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 1 Mar 2026 18:20:14 -1000
Subject: [PATCH 10/10] [core] Wake main loop from ISR in
 enable_loop_soon_any_context() (#14383)

---
 esphome/components/socket/__init__.py |  7 ++++---
 esphome/core/application.h            |  8 +++++++-
 esphome/core/component.cpp            |  8 +++++++-
 esphome/core/lwip_fast_select.c       | 24 +++++++++++++++++++-----
 esphome/core/lwip_fast_select.h       |  7 +++++++
 5 files changed, 44 insertions(+), 10 deletions(-)

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/core/application.h b/esphome/core/application.h
index 13e0f63885..d2345e2b0b 100644
--- a/esphome/core/application.h
+++ b/esphome/core/application.h
@@ -501,7 +501,7 @@ 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).
@@ -509,6 +509,12 @@ 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
 #endif
 
diff --git a/esphome/core/component.cpp b/esphome/core/component.cpp
index fd4e0d2984..5afd901da2 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) {
diff --git a/esphome/core/lwip_fast_select.c b/esphome/core/lwip_fast_select.c
index da0f1f337a..989f66e9be 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>
@@ -239,4 +238,19 @@ 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 b7a70a8f9f..6fce34fd76 100644
--- a/esphome/core/lwip_fast_select.h
+++ b/esphome/core/lwip_fast_select.h
@@ -33,6 +33,13 @@ 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