diff --git a/esphome/components/addressable_light/addressable_light_display.h b/esphome/components/addressable_light/addressable_light_display.h
index f47389fd05a..53f8604b7de 100644
--- a/esphome/components/addressable_light/addressable_light_display.h
+++ b/esphome/components/addressable_light/addressable_light_display.h
@@ -25,11 +25,13 @@ class AddressableLightDisplay : public display::DisplayBuffer {
       if (enabled_ && !enabled) {  // enabled -> disabled
         // - Tell the parent light to refresh, effectively wiping the display. Also
         //   restores the previous effect (if any).
-        light_state_->make_call().set_effect(this->last_effect_).perform();
+        if (this->last_effect_index_.has_value()) {
+          light_state_->make_call().set_effect(*this->last_effect_index_).perform();
+        }
 
       } else if (!enabled_ && enabled) {  // disabled -> enabled
-        // - Save the current effect.
-        this->last_effect_ = light_state_->get_effect_name();
+        // - Save the current effect index.
+        this->last_effect_index_ = light_state_->get_current_effect_index();
         // - Disable any current effect.
         light_state_->make_call().set_effect(0).perform();
       }
@@ -56,7 +58,7 @@ class AddressableLightDisplay : public display::DisplayBuffer {
   int32_t width_;
   int32_t height_;
   std::vector<Color> addressable_light_buffer_;
-  optional<std::string> last_effect_;
+  optional<uint32_t> last_effect_index_;
   optional<std::function<int(int, int)>> pixel_mapper_f_;
 };
 }  // namespace addressable_light
diff --git a/esphome/components/api/api.proto b/esphome/components/api/api.proto
index 43b721c2d53..5efd8396735 100644
--- a/esphome/components/api/api.proto
+++ b/esphome/components/api/api.proto
@@ -2425,7 +2425,7 @@ message ZWaveProxyFrame {
   option (ifdef) = "USE_ZWAVE_PROXY";
   option (no_delay) = true;
 
-  bytes data = 1 [(pointer_to_buffer) = true];
+  bytes data = 1;
 }
 
 enum ZWaveProxyRequestType {
@@ -2439,5 +2439,5 @@ message ZWaveProxyRequest {
   option (ifdef) = "USE_ZWAVE_PROXY";
 
   ZWaveProxyRequestType type = 1;
-  bytes data = 2 [(pointer_to_buffer) = true];
+  bytes data = 2;
 }
diff --git a/esphome/components/api/api_connection.cpp b/esphome/components/api/api_connection.cpp
index 8588651968e..2ecd54bb00a 100644
--- a/esphome/components/api/api_connection.cpp
+++ b/esphome/components/api/api_connection.cpp
@@ -1530,7 +1530,7 @@ bool APIConnection::send_hello_response(const HelloRequest &msg) {
 
   HelloResponse resp;
   resp.api_version_major = 1;
-  resp.api_version_minor = 13;
+  resp.api_version_minor = 14;
   // Send only the version string - the client only logs this for debugging and doesn't use it otherwise
   resp.set_server_info(ESPHOME_VERSION_REF);
   resp.set_name(StringRef(App.get_name()));
diff --git a/esphome/components/api/api_connection.h b/esphome/components/api/api_connection.h
index 47609f79b68..59c42aa0330 100644
--- a/esphome/components/api/api_connection.h
+++ b/esphome/components/api/api_connection.h
@@ -24,9 +24,10 @@ struct ClientInfo {
 // Keepalive timeout in milliseconds
 static constexpr uint32_t KEEPALIVE_TIMEOUT_MS = 60000;
 // Maximum number of entities to process in a single batch during initial state/info sending
-// This was increased from 20 to 24 after removing the unique_id field from entity info messages,
-// which reduced message sizes allowing more entities per batch without exceeding packet limits
-static constexpr size_t MAX_INITIAL_PER_BATCH = 24;
+// API 1.14+ clients compute object_id client-side, so messages are smaller and we can fit more per batch
+// TODO: Remove MAX_INITIAL_PER_BATCH_LEGACY before 2026.7.0 - all clients should support API 1.14 by then
+static constexpr size_t MAX_INITIAL_PER_BATCH_LEGACY = 24;  // For clients < API 1.14 (includes object_id)
+static constexpr size_t MAX_INITIAL_PER_BATCH = 34;         // For clients >= API 1.14 (no object_id)
 // Maximum number of packets to process in a single batch (platform-dependent)
 // This limit exists to prevent stack overflow from the PacketInfo array in process_batch_
 // Each PacketInfo is 8 bytes, so 64 * 8 = 512 bytes, 32 * 8 = 256 bytes
@@ -323,10 +324,16 @@ class APIConnection final : public APIServerConnection {
                                               APIConnection *conn, uint32_t remaining_size, bool is_single) {
     // Set common fields that are shared by all entity types
     msg.key = entity->get_object_id_hash();
-    // Get object_id with zero heap allocation
-    // Static case returns direct reference, dynamic case uses buffer
+
+    // API 1.14+ clients compute object_id client-side from the entity name
+    // For older clients, we must send object_id for backward compatibility
+    // See: https://github.com/esphome/backlog/issues/76
+    // TODO: Remove this backward compat code before 2026.7.0 - all clients should support API 1.14 by then
+    // Buffer must remain in scope until encode_message_to_buffer is called
     char object_id_buf[OBJECT_ID_MAX_LEN];
-    msg.set_object_id(entity->get_object_id_to(object_id_buf));
+    if (!conn->client_supports_api_version(1, 14)) {
+      msg.set_object_id(entity->get_object_id_to(object_id_buf));
+    }
 
     if (entity->has_own_name()) {
       msg.set_name(entity->get_name());
@@ -349,16 +356,24 @@ class APIConnection final : public APIServerConnection {
   inline bool check_voice_assistant_api_connection_() const;
 #endif
 
+  // Get the max batch size based on client API version
+  // API 1.14+ clients don't receive object_id, so messages are smaller and more fit per batch
+  // TODO: Remove this method before 2026.7.0 and use MAX_INITIAL_PER_BATCH directly
+  size_t get_max_batch_size_() const {
+    return this->client_supports_api_version(1, 14) ? MAX_INITIAL_PER_BATCH : MAX_INITIAL_PER_BATCH_LEGACY;
+  }
+
   // Helper method to process multiple entities from an iterator in a batch
   template<typename Iterator> void process_iterator_batch_(Iterator &iterator) {
     size_t initial_size = this->deferred_batch_.size();
-    while (!iterator.completed() && (this->deferred_batch_.size() - initial_size) < MAX_INITIAL_PER_BATCH) {
+    size_t max_batch = this->get_max_batch_size_();
+    while (!iterator.completed() && (this->deferred_batch_.size() - initial_size) < max_batch) {
       iterator.advance();
     }
 
     // If the batch is full, process it immediately
     // Note: iterator.advance() already calls schedule_batch_() via schedule_message_()
-    if (this->deferred_batch_.size() >= MAX_INITIAL_PER_BATCH) {
+    if (this->deferred_batch_.size() >= max_batch) {
       this->process_batch_();
     }
   }
diff --git a/esphome/components/api/api_frame_helper.cpp b/esphome/components/api/api_frame_helper.cpp
index 20f8fcaf613..420f42a90a0 100644
--- a/esphome/components/api/api_frame_helper.cpp
+++ b/esphome/components/api/api_frame_helper.cpp
@@ -13,12 +13,26 @@ namespace esphome::api {
 
 static const char *const TAG = "api.frame_helper";
 
+// Maximum bytes to log in hex format (168 * 3 = 504, under TX buffer size of 512)
+static constexpr size_t API_MAX_LOG_BYTES = 168;
+
 #define HELPER_LOG(msg, ...) \
   ESP_LOGVV(TAG, "%s (%s): " msg, this->client_info_->name.c_str(), this->client_info_->peername.c_str(), ##__VA_ARGS__)
 
 #ifdef HELPER_LOG_PACKETS
-#define LOG_PACKET_RECEIVED(buffer) ESP_LOGVV(TAG, "Received frame: %s", format_hex_pretty(buffer).c_str())
-#define LOG_PACKET_SENDING(data, len) ESP_LOGVV(TAG, "Sending raw: %s", format_hex_pretty(data, len).c_str())
+#define LOG_PACKET_RECEIVED(buffer) \
+  do { \
+    char hex_buf_[format_hex_pretty_size(API_MAX_LOG_BYTES)]; \
+    ESP_LOGVV(TAG, "Received frame: %s", \
+              format_hex_pretty_to(hex_buf_, (buffer).data(), \
+                                   (buffer).size() < API_MAX_LOG_BYTES ? (buffer).size() : API_MAX_LOG_BYTES)); \
+  } while (0)
+#define LOG_PACKET_SENDING(data, len) \
+  do { \
+    char hex_buf_[format_hex_pretty_size(API_MAX_LOG_BYTES)]; \
+    ESP_LOGVV(TAG, "Sending raw: %s", \
+              format_hex_pretty_to(hex_buf_, data, (len) < API_MAX_LOG_BYTES ? (len) : API_MAX_LOG_BYTES)); \
+  } while (0)
 #else
 #define LOG_PACKET_RECEIVED(buffer) ((void) 0)
 #define LOG_PACKET_SENDING(data, len) ((void) 0)
diff --git a/esphome/components/api/api_frame_helper_noise.cpp b/esphome/components/api/api_frame_helper_noise.cpp
index 1d6f32ee9df..37b497e2a13 100644
--- a/esphome/components/api/api_frame_helper_noise.cpp
+++ b/esphome/components/api/api_frame_helper_noise.cpp
@@ -24,12 +24,26 @@ static const char *const PROLOGUE_INIT = "NoiseAPIInit";
 #endif
 static constexpr size_t PROLOGUE_INIT_LEN = 12;  // strlen("NoiseAPIInit")
 
+// Maximum bytes to log in hex format (168 * 3 = 504, under TX buffer size of 512)
+static constexpr size_t API_MAX_LOG_BYTES = 168;
+
 #define HELPER_LOG(msg, ...) \
   ESP_LOGVV(TAG, "%s (%s): " msg, this->client_info_->name.c_str(), this->client_info_->peername.c_str(), ##__VA_ARGS__)
 
 #ifdef HELPER_LOG_PACKETS
-#define LOG_PACKET_RECEIVED(buffer) ESP_LOGVV(TAG, "Received frame: %s", format_hex_pretty(buffer).c_str())
-#define LOG_PACKET_SENDING(data, len) ESP_LOGVV(TAG, "Sending raw: %s", format_hex_pretty(data, len).c_str())
+#define LOG_PACKET_RECEIVED(buffer) \
+  do { \
+    char hex_buf_[format_hex_pretty_size(API_MAX_LOG_BYTES)]; \
+    ESP_LOGVV(TAG, "Received frame: %s", \
+              format_hex_pretty_to(hex_buf_, (buffer).data(), \
+                                   (buffer).size() < API_MAX_LOG_BYTES ? (buffer).size() : API_MAX_LOG_BYTES)); \
+  } while (0)
+#define LOG_PACKET_SENDING(data, len) \
+  do { \
+    char hex_buf_[format_hex_pretty_size(API_MAX_LOG_BYTES)]; \
+    ESP_LOGVV(TAG, "Sending raw: %s", \
+              format_hex_pretty_to(hex_buf_, data, (len) < API_MAX_LOG_BYTES ? (len) : API_MAX_LOG_BYTES)); \
+  } while (0)
 #else
 #define LOG_PACKET_RECEIVED(buffer) ((void) 0)
 #define LOG_PACKET_SENDING(data, len) ((void) 0)
diff --git a/esphome/components/api/api_frame_helper_plaintext.cpp b/esphome/components/api/api_frame_helper_plaintext.cpp
index b5d90b24291..8b7d002d7c7 100644
--- a/esphome/components/api/api_frame_helper_plaintext.cpp
+++ b/esphome/components/api/api_frame_helper_plaintext.cpp
@@ -18,12 +18,26 @@ namespace esphome::api {
 
 static const char *const TAG = "api.plaintext";
 
+// Maximum bytes to log in hex format (168 * 3 = 504, under TX buffer size of 512)
+static constexpr size_t API_MAX_LOG_BYTES = 168;
+
 #define HELPER_LOG(msg, ...) \
   ESP_LOGVV(TAG, "%s (%s): " msg, this->client_info_->name.c_str(), this->client_info_->peername.c_str(), ##__VA_ARGS__)
 
 #ifdef HELPER_LOG_PACKETS
-#define LOG_PACKET_RECEIVED(buffer) ESP_LOGVV(TAG, "Received frame: %s", format_hex_pretty(buffer).c_str())
-#define LOG_PACKET_SENDING(data, len) ESP_LOGVV(TAG, "Sending raw: %s", format_hex_pretty(data, len).c_str())
+#define LOG_PACKET_RECEIVED(buffer) \
+  do { \
+    char hex_buf_[format_hex_pretty_size(API_MAX_LOG_BYTES)]; \
+    ESP_LOGVV(TAG, "Received frame: %s", \
+              format_hex_pretty_to(hex_buf_, (buffer).data(), \
+                                   (buffer).size() < API_MAX_LOG_BYTES ? (buffer).size() : API_MAX_LOG_BYTES)); \
+  } while (0)
+#define LOG_PACKET_SENDING(data, len) \
+  do { \
+    char hex_buf_[format_hex_pretty_size(API_MAX_LOG_BYTES)]; \
+    ESP_LOGVV(TAG, "Sending raw: %s", \
+              format_hex_pretty_to(hex_buf_, data, (len) < API_MAX_LOG_BYTES ? (len) : API_MAX_LOG_BYTES)); \
+  } while (0)
 #else
 #define LOG_PACKET_RECEIVED(buffer) ((void) 0)
 #define LOG_PACKET_SENDING(data, len) ((void) 0)
diff --git a/esphome/components/api/api_pb2.h b/esphome/components/api/api_pb2.h
index 6275b4c211f..e08cf65bb96 100644
--- a/esphome/components/api/api_pb2.h
+++ b/esphome/components/api/api_pb2.h
@@ -1046,7 +1046,7 @@ class SubscribeLogsRequest final : public ProtoDecodableMessage {
 class SubscribeLogsResponse final : public ProtoMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 29;
-  static constexpr uint8_t ESTIMATED_SIZE = 11;
+  static constexpr uint8_t ESTIMATED_SIZE = 21;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "subscribe_logs_response"; }
 #endif
@@ -1069,7 +1069,7 @@ class SubscribeLogsResponse final : public ProtoMessage {
 class NoiseEncryptionSetKeyRequest final : public ProtoDecodableMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 124;
-  static constexpr uint8_t ESTIMATED_SIZE = 9;
+  static constexpr uint8_t ESTIMATED_SIZE = 19;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "noise_encryption_set_key_request"; }
 #endif
@@ -1161,7 +1161,7 @@ class HomeassistantActionRequest final : public ProtoMessage {
 class HomeassistantActionResponse final : public ProtoDecodableMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 130;
-  static constexpr uint8_t ESTIMATED_SIZE = 24;
+  static constexpr uint8_t ESTIMATED_SIZE = 34;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "homeassistant_action_response"; }
 #endif
@@ -1388,7 +1388,7 @@ class ListEntitiesCameraResponse final : public InfoResponseProtoMessage {
 class CameraImageResponse final : public StateResponseProtoMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 44;
-  static constexpr uint8_t ESTIMATED_SIZE = 20;
+  static constexpr uint8_t ESTIMATED_SIZE = 30;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "camera_image_response"; }
 #endif
@@ -2123,7 +2123,7 @@ class BluetoothGATTReadRequest final : public ProtoDecodableMessage {
 class BluetoothGATTReadResponse final : public ProtoMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 74;
-  static constexpr uint8_t ESTIMATED_SIZE = 17;
+  static constexpr uint8_t ESTIMATED_SIZE = 27;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "bluetooth_gatt_read_response"; }
 #endif
@@ -2146,7 +2146,7 @@ class BluetoothGATTReadResponse final : public ProtoMessage {
 class BluetoothGATTWriteRequest final : public ProtoDecodableMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 75;
-  static constexpr uint8_t ESTIMATED_SIZE = 19;
+  static constexpr uint8_t ESTIMATED_SIZE = 29;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "bluetooth_gatt_write_request"; }
 #endif
@@ -2182,7 +2182,7 @@ class BluetoothGATTReadDescriptorRequest final : public ProtoDecodableMessage {
 class BluetoothGATTWriteDescriptorRequest final : public ProtoDecodableMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 77;
-  static constexpr uint8_t ESTIMATED_SIZE = 17;
+  static constexpr uint8_t ESTIMATED_SIZE = 27;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "bluetooth_gatt_write_descriptor_request"; }
 #endif
@@ -2218,7 +2218,7 @@ class BluetoothGATTNotifyRequest final : public ProtoDecodableMessage {
 class BluetoothGATTNotifyDataResponse final : public ProtoMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 79;
-  static constexpr uint8_t ESTIMATED_SIZE = 17;
+  static constexpr uint8_t ESTIMATED_SIZE = 27;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "bluetooth_gatt_notify_data_response"; }
 #endif
diff --git a/esphome/components/ch422g/ch422g.cpp b/esphome/components/ch422g/ch422g.cpp
index 9a4e342525b..f47b67da6fa 100644
--- a/esphome/components/ch422g/ch422g.cpp
+++ b/esphome/components/ch422g/ch422g.cpp
@@ -128,7 +128,9 @@ void CH422GGPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this->
 bool CH422GGPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) ^ this->inverted_; }
 
 void CH422GGPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value ^ this->inverted_); }
-std::string CH422GGPIOPin::dump_summary() const { return str_sprintf("EXIO%u via CH422G", pin_); }
+size_t CH422GGPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "EXIO%u via CH422G", this->pin_);
+}
 void CH422GGPIOPin::set_flags(gpio::Flags flags) {
   flags_ = flags;
   this->parent_->pin_mode(this->pin_, flags);
diff --git a/esphome/components/ch422g/ch422g.h b/esphome/components/ch422g/ch422g.h
index 1193a3db270..8ed63db90ae 100644
--- a/esphome/components/ch422g/ch422g.h
+++ b/esphome/components/ch422g/ch422g.h
@@ -50,7 +50,7 @@ class CH422GGPIOPin : public GPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_parent(CH422GComponent *parent) { parent_ = parent; }
   void set_pin(uint8_t pin) { pin_ = pin; }
diff --git a/esphome/components/esp32/gpio.cpp b/esphome/components/esp32/gpio.cpp
index a98245b889e..4b53d3a1721 100644
--- a/esphome/components/esp32/gpio.cpp
+++ b/esphome/components/esp32/gpio.cpp
@@ -97,10 +97,8 @@ void ESP32InternalGPIOPin::attach_interrupt(void (*func)(void *), void *arg, gpi
   gpio_isr_handler_add(this->get_pin_num(), func, arg);
 }
 
-std::string ESP32InternalGPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "GPIO%" PRIu32, static_cast<uint32_t>(this->pin_));
-  return buffer;
+size_t ESP32InternalGPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "GPIO%" PRIu32, static_cast<uint32_t>(this->pin_));
 }
 
 void ESP32InternalGPIOPin::setup() {
diff --git a/esphome/components/esp32/gpio.h b/esphome/components/esp32/gpio.h
index d30f4bdcbad..3c13bd9b4ff 100644
--- a/esphome/components/esp32/gpio.h
+++ b/esphome/components/esp32/gpio.h
@@ -24,7 +24,7 @@ class ESP32InternalGPIOPin : public InternalGPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
   void detach_interrupt() const override;
   ISRInternalGPIOPin to_isr() const override;
   uint8_t get_pin() const override { return this->pin_; }
diff --git a/esphome/components/esp32_improv/__init__.py b/esphome/components/esp32_improv/__init__.py
index 2e69d400ca0..ad2f057163b 100644
--- a/esphome/components/esp32_improv/__init__.py
+++ b/esphome/components/esp32_improv/__init__.py
@@ -3,7 +3,7 @@ import esphome.codegen as cg
 from esphome.components import binary_sensor, esp32_ble, improv_base, output
 from esphome.components.esp32_ble import BTLoggers
 import esphome.config_validation as cv
-from esphome.const import CONF_ID, CONF_ON_STATE, CONF_TRIGGER_ID
+from esphome.const import CONF_ID, CONF_ON_START, CONF_ON_STATE, CONF_TRIGGER_ID
 
 AUTO_LOAD = ["esp32_ble_server", "improv_base"]
 CODEOWNERS = ["@jesserockz"]
@@ -15,7 +15,6 @@ CONF_BLE_SERVER_ID = "ble_server_id"
 CONF_IDENTIFY_DURATION = "identify_duration"
 CONF_ON_PROVISIONED = "on_provisioned"
 CONF_ON_PROVISIONING = "on_provisioning"
-CONF_ON_START = "on_start"
 CONF_ON_STOP = "on_stop"
 CONF_STATUS_INDICATOR = "status_indicator"
 CONF_WIFI_TIMEOUT = "wifi_timeout"
diff --git a/esphome/components/esp8266/__init__.py b/esphome/components/esp8266/__init__.py
index c4969a79b2e..77ccaf52c1f 100644
--- a/esphome/components/esp8266/__init__.py
+++ b/esphome/components/esp8266/__init__.py
@@ -28,6 +28,7 @@ from .const import (
     KEY_ESP8266,
     KEY_FLASH_SIZE,
     KEY_PIN_INITIAL_STATES,
+    KEY_WAVEFORM_REQUIRED,
     esp8266_ns,
 )
 from .gpio import PinInitialState, add_pin_initial_states_array
@@ -192,7 +193,12 @@ async def to_code(config):
 
     cg.add_platformio_option(
         "extra_scripts",
-        ["pre:testing_mode.py", "pre:exclude_updater.py", "post:post_build.py"],
+        [
+            "pre:testing_mode.py",
+            "pre:exclude_updater.py",
+            "pre:exclude_waveform.py",
+            "post:post_build.py",
+        ],
     )
 
     conf = config[CONF_FRAMEWORK]
@@ -264,10 +270,24 @@ async def to_code(config):
             cg.add_platformio_option("board_build.ldscript", ld_script)
 
     CORE.add_job(add_pin_initial_states_array)
+    CORE.add_job(finalize_waveform_config)
+
+
+@coroutine_with_priority(CoroPriority.WORKAROUNDS)
+async def finalize_waveform_config() -> None:
+    """Add waveform stubs define if waveform is not required.
+
+    This runs at WORKAROUNDS priority (-999) to ensure all components
+    have had a chance to call require_waveform() first.
+    """
+    if not CORE.data.get(KEY_ESP8266, {}).get(KEY_WAVEFORM_REQUIRED, False):
+        # No component needs waveform - enable stubs and exclude Arduino waveform code
+        # Use build flag (visible to both C++ code and PlatformIO script)
+        cg.add_build_flag("-DUSE_ESP8266_WAVEFORM_STUBS")
 
 
 # Called by writer.py
-def copy_files():
+def copy_files() -> None:
     dir = Path(__file__).parent
     post_build_file = dir / "post_build.py.script"
     copy_file_if_changed(
@@ -284,3 +304,8 @@ def copy_files():
         exclude_updater_file,
         CORE.relative_build_path("exclude_updater.py"),
     )
+    exclude_waveform_file = dir / "exclude_waveform.py.script"
+    copy_file_if_changed(
+        exclude_waveform_file,
+        CORE.relative_build_path("exclude_waveform.py"),
+    )
diff --git a/esphome/components/esp8266/const.py b/esphome/components/esp8266/const.py
index b718306b01e..14425cde68e 100644
--- a/esphome/components/esp8266/const.py
+++ b/esphome/components/esp8266/const.py
@@ -1,4 +1,5 @@
 import esphome.codegen as cg
+from esphome.core import CORE
 
 KEY_ESP8266 = "esp8266"
 KEY_BOARD = "board"
@@ -6,6 +7,25 @@ KEY_PIN_INITIAL_STATES = "pin_initial_states"
 CONF_RESTORE_FROM_FLASH = "restore_from_flash"
 CONF_EARLY_PIN_INIT = "early_pin_init"
 KEY_FLASH_SIZE = "flash_size"
+KEY_WAVEFORM_REQUIRED = "waveform_required"
 
 # esp8266 namespace is already defined by arduino, manually prefix esphome
 esp8266_ns = cg.global_ns.namespace("esphome").namespace("esp8266")
+
+
+def require_waveform() -> None:
+    """Mark that Arduino waveform/PWM support is required.
+
+    Call this from components that need the Arduino waveform generator
+    (startWaveform, stopWaveform, analogWrite, Tone, Servo).
+
+    If no component calls this, the waveform code is excluded from the build
+    to save ~596 bytes of RAM and 464 bytes of flash.
+
+    Example:
+        from esphome.components.esp8266.const import require_waveform
+
+        async def to_code(config):
+            require_waveform()
+    """
+    CORE.data.setdefault(KEY_ESP8266, {})[KEY_WAVEFORM_REQUIRED] = True
diff --git a/esphome/components/esp8266/exclude_waveform.py.script b/esphome/components/esp8266/exclude_waveform.py.script
new file mode 100644
index 00000000000..35d6bc31f61
--- /dev/null
+++ b/esphome/components/esp8266/exclude_waveform.py.script
@@ -0,0 +1,50 @@
+# pylint: disable=E0602
+Import("env")  # noqa
+
+import os
+
+# Filter out waveform/PWM code from the Arduino core build
+# This saves ~596 bytes of RAM and 464 bytes of flash by not
+# instantiating the waveform generator state structures (wvfState + pwmState).
+#
+# The waveform code is used by: analogWrite, Tone, Servo, and direct
+# startWaveform/stopWaveform calls. ESPHome's esp8266_pwm component
+# calls require_waveform() to keep this code when needed.
+#
+# When excluded, we provide stub implementations of stopWaveform() and
+# _stopPWM() since digitalWrite() calls these unconditionally.
+
+
+def has_define_flag(env, name):
+    """Check if a define exists in the build flags."""
+    define_flag = f"-D{name}"
+    # Check BUILD_FLAGS (where ESPHome puts its defines)
+    for flag in env.get("BUILD_FLAGS", []):
+        if flag == define_flag or flag.startswith(f"{define_flag}="):
+            return True
+    # Also check CPPDEFINES list (parsed defines)
+    for define in env.get("CPPDEFINES", []):
+        if isinstance(define, tuple):
+            if define[0] == name:
+                return True
+        elif define == name:
+            return True
+    return False
+
+# USE_ESP8266_WAVEFORM_STUBS is defined when no component needs waveform
+if has_define_flag(env, "USE_ESP8266_WAVEFORM_STUBS"):
+
+    def filter_waveform_from_core(env, node):
+        """Filter callback to exclude waveform files from framework build."""
+        path = node.get_path()
+        filename = os.path.basename(path)
+        if filename in (
+            "core_esp8266_waveform_pwm.cpp",
+            "core_esp8266_waveform_phase.cpp",
+        ):
+            print(f"ESPHome: Excluding {filename} from build (waveform not required)")
+            return None
+        return node
+
+    # Apply the filter to framework sources
+    env.AddBuildMiddleware(filter_waveform_from_core, "**/cores/esp8266/*.cpp")
diff --git a/esphome/components/esp8266/gpio.cpp b/esphome/components/esp8266/gpio.cpp
index 124df39ce3d..7a5ee08984b 100644
--- a/esphome/components/esp8266/gpio.cpp
+++ b/esphome/components/esp8266/gpio.cpp
@@ -98,10 +98,8 @@ void ESP8266GPIOPin::pin_mode(gpio::Flags flags) {
   pinMode(pin_, flags_to_mode(flags, pin_));  // NOLINT
 }
 
-std::string ESP8266GPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "GPIO%u", pin_);
-  return buffer;
+size_t ESP8266GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "GPIO%u", this->pin_);
 }
 
 bool ESP8266GPIOPin::digital_read() {
diff --git a/esphome/components/esp8266/gpio.h b/esphome/components/esp8266/gpio.h
index 213a5c54bed..ff149abfbe7 100644
--- a/esphome/components/esp8266/gpio.h
+++ b/esphome/components/esp8266/gpio.h
@@ -17,7 +17,7 @@ class ESP8266GPIOPin : public InternalGPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
   void detach_interrupt() const override;
   ISRInternalGPIOPin to_isr() const override;
   uint8_t get_pin() const override { return pin_; }
diff --git a/esphome/components/esp8266/waveform_stubs.cpp b/esphome/components/esp8266/waveform_stubs.cpp
new file mode 100644
index 00000000000..686e03c6a90
--- /dev/null
+++ b/esphome/components/esp8266/waveform_stubs.cpp
@@ -0,0 +1,34 @@
+#ifdef USE_ESP8266_WAVEFORM_STUBS
+
+// Stub implementations for Arduino waveform/PWM functions.
+//
+// When the waveform generator is not needed (no esp8266_pwm component),
+// we exclude core_esp8266_waveform_pwm.cpp from the build to save ~596 bytes
+// of RAM and 464 bytes of flash.
+//
+// These stubs satisfy calls from the Arduino GPIO code when the real
+// waveform implementation is excluded. They must be in the global namespace
+// with C linkage to match the Arduino core function declarations.
+
+#include <cstdint>
+
+// Empty namespace to satisfy linter - actual stubs must be at global scope
+namespace esphome::esp8266 {}  // namespace esphome::esp8266
+
+extern "C" {
+
+// Called by Arduino GPIO code to stop any waveform on a pin
+int stopWaveform(uint8_t pin) {
+  (void) pin;
+  return 1;  // Success (no waveform to stop)
+}
+
+// Called by Arduino GPIO code to stop any PWM on a pin
+bool _stopPWM(uint8_t pin) {
+  (void) pin;
+  return false;  // No PWM was running
+}
+
+}  // extern "C"
+
+#endif  // USE_ESP8266_WAVEFORM_STUBS
diff --git a/esphome/components/esp8266_pwm/output.py b/esphome/components/esp8266_pwm/output.py
index 2ddf4b90147..a78831c516c 100644
--- a/esphome/components/esp8266_pwm/output.py
+++ b/esphome/components/esp8266_pwm/output.py
@@ -1,6 +1,7 @@
 from esphome import automation, pins
 import esphome.codegen as cg
 from esphome.components import output
+from esphome.components.esp8266.const import require_waveform
 import esphome.config_validation as cv
 from esphome.const import CONF_FREQUENCY, CONF_ID, CONF_NUMBER, CONF_PIN
 
@@ -34,7 +35,9 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config) -> None:
+    require_waveform()
+
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await output.register_output(var, config)
diff --git a/esphome/components/gps/__init__.py b/esphome/components/gps/__init__.py
index a872cf70151..2135189bd53 100644
--- a/esphome/components/gps/__init__.py
+++ b/esphome/components/gps/__init__.py
@@ -11,6 +11,7 @@ from esphome.const import (
     CONF_SPEED,
     DEVICE_CLASS_SPEED,
     STATE_CLASS_MEASUREMENT,
+    STATE_CLASS_MEASUREMENT_ANGLE,
     UNIT_DEGREES,
     UNIT_KILOMETER_PER_HOUR,
     UNIT_METER,
@@ -21,6 +22,7 @@ CONF_HDOP = "hdop"
 
 ICON_ALTIMETER = "mdi:altimeter"
 ICON_COMPASS = "mdi:compass"
+ICON_CIRCLE_DOUBLE = "mdi:circle-double"
 ICON_LATITUDE = "mdi:latitude"
 ICON_LONGITUDE = "mdi:longitude"
 ICON_SATELLITE = "mdi:satellite-variant"
@@ -50,7 +52,7 @@ CONFIG_SCHEMA = cv.All(
                 unit_of_measurement=UNIT_DEGREES,
                 icon=ICON_LONGITUDE,
                 accuracy_decimals=6,
-                state_class=STATE_CLASS_MEASUREMENT,
+                state_class=STATE_CLASS_MEASUREMENT_ANGLE,
             ),
             cv.Optional(CONF_SPEED): sensor.sensor_schema(
                 unit_of_measurement=UNIT_KILOMETER_PER_HOUR,
@@ -63,7 +65,7 @@ CONFIG_SCHEMA = cv.All(
                 unit_of_measurement=UNIT_DEGREES,
                 icon=ICON_COMPASS,
                 accuracy_decimals=2,
-                state_class=STATE_CLASS_MEASUREMENT,
+                state_class=STATE_CLASS_MEASUREMENT_ANGLE,
             ),
             cv.Optional(CONF_ALTITUDE): sensor.sensor_schema(
                 unit_of_measurement=UNIT_METER,
@@ -72,11 +74,14 @@ CONFIG_SCHEMA = cv.All(
                 state_class=STATE_CLASS_MEASUREMENT,
             ),
             cv.Optional(CONF_SATELLITES): sensor.sensor_schema(
+                # no unit_of_measurement
                 icon=ICON_SATELLITE,
                 accuracy_decimals=0,
                 state_class=STATE_CLASS_MEASUREMENT,
             ),
             cv.Optional(CONF_HDOP): sensor.sensor_schema(
+                # no unit_of_measurement
+                icon=ICON_CIRCLE_DOUBLE,
                 accuracy_decimals=3,
                 state_class=STATE_CLASS_MEASUREMENT,
             ),
diff --git a/esphome/components/hlw8012/hlw8012.cpp b/esphome/components/hlw8012/hlw8012.cpp
index 73696bd2a53..70a05e4f72f 100644
--- a/esphome/components/hlw8012/hlw8012.cpp
+++ b/esphome/components/hlw8012/hlw8012.cpp
@@ -34,9 +34,9 @@ void HLW8012Component::setup() {
 }
 void HLW8012Component::dump_config() {
   ESP_LOGCONFIG(TAG, "HLW8012:");
-  LOG_PIN("  SEL Pin: ", this->sel_pin_)
-  LOG_PIN("  CF Pin: ", this->cf_pin_)
-  LOG_PIN("  CF1 Pin: ", this->cf1_pin_)
+  LOG_PIN("  SEL Pin: ", this->sel_pin_);
+  LOG_PIN("  CF Pin: ", this->cf_pin_);
+  LOG_PIN("  CF1 Pin: ", this->cf1_pin_);
   ESP_LOGCONFIG(TAG,
                 "  Change measurement mode every %" PRIu32 "\n"
                 "  Current resistor: %.1f mΩ\n"
diff --git a/esphome/components/host/gpio.cpp b/esphome/components/host/gpio.cpp
index e46f158513a..f99b82bcc20 100644
--- a/esphome/components/host/gpio.cpp
+++ b/esphome/components/host/gpio.cpp
@@ -25,11 +25,7 @@ void HostGPIOPin::attach_interrupt(void (*func)(void *), void *arg, gpio::Interr
 }
 void HostGPIOPin::pin_mode(gpio::Flags flags) { ESP_LOGD(TAG, "Setting pin %d mode to %02X", pin_, (uint32_t) flags); }
 
-std::string HostGPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "GPIO%u", pin_);
-  return buffer;
-}
+size_t HostGPIOPin::dump_summary(char *buffer, size_t len) const { return snprintf(buffer, len, "GPIO%u", this->pin_); }
 
 bool HostGPIOPin::digital_read() { return inverted_; }
 void HostGPIOPin::digital_write(bool value) {
diff --git a/esphome/components/host/gpio.h b/esphome/components/host/gpio.h
index ae677291b9e..ea6b13f436e 100644
--- a/esphome/components/host/gpio.h
+++ b/esphome/components/host/gpio.h
@@ -17,7 +17,7 @@ class HostGPIOPin : public InternalGPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
   void detach_interrupt() const override;
   ISRInternalGPIOPin to_isr() const override;
   uint8_t get_pin() const override { return pin_; }
diff --git a/esphome/components/hte501/hte501.cpp b/esphome/components/hte501/hte501.cpp
index b7d3be63fe8..cde68861098 100644
--- a/esphome/components/hte501/hte501.cpp
+++ b/esphome/components/hte501/hte501.cpp
@@ -7,6 +7,8 @@ namespace hte501 {
 
 static const char *const TAG = "hte501";
 
+static constexpr size_t HTE501_SERIAL_NUMBER_SIZE = 7;
+
 void HTE501Component::setup() {
   uint8_t address[] = {0x70, 0x29};
   uint8_t identification[9];
@@ -16,7 +18,10 @@ void HTE501Component::setup() {
     this->mark_failed();
     return;
   }
-  ESP_LOGV(TAG, "    Serial Number: 0x%s", format_hex(identification + 0, 7).c_str());
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
+  char serial_hex[format_hex_size(HTE501_SERIAL_NUMBER_SIZE)];
+#endif
+  ESP_LOGV(TAG, "    Serial Number: 0x%s", format_hex_to(serial_hex, identification, HTE501_SERIAL_NUMBER_SIZE));
 }
 
 void HTE501Component::dump_config() {
diff --git a/esphome/components/kuntze/kuntze.cpp b/esphome/components/kuntze/kuntze.cpp
index 30f98aaa995..1b772d062ca 100644
--- a/esphome/components/kuntze/kuntze.cpp
+++ b/esphome/components/kuntze/kuntze.cpp
@@ -1,4 +1,5 @@
 #include "kuntze.h"
+#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 #include "esphome/core/application.h"
 
@@ -10,11 +11,17 @@ static const char *const TAG = "kuntze";
 static const uint8_t CMD_READ_REG = 0x03;
 static const uint16_t REGISTER[] = {4136, 4160, 4680, 6000, 4688, 4728, 5832};
 
+// Maximum bytes to log for Modbus responses (2 registers = 4, plus count = 5)
+static constexpr size_t KUNTZE_MAX_LOG_BYTES = 8;
+
 void Kuntze::on_modbus_data(const std::vector<uint8_t> &data) {
   auto get_16bit = [&](int i) -> uint16_t { return (uint16_t(data[i * 2]) << 8) | uint16_t(data[i * 2 + 1]); };
 
   this->waiting_ = false;
-  ESP_LOGV(TAG, "Data: %s", format_hex_pretty(data).c_str());
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
+  char hex_buf[format_hex_pretty_size(KUNTZE_MAX_LOG_BYTES)];
+#endif
+  ESP_LOGV(TAG, "Data: %s", format_hex_pretty_to(hex_buf, data.data(), data.size()));
 
   float value = (float) get_16bit(0);
   for (int i = 0; i < data[3]; i++)
diff --git a/esphome/components/libretiny/gpio_arduino.cpp b/esphome/components/libretiny/gpio_arduino.cpp
index 7a1e014ea4c..0b14c77cf27 100644
--- a/esphome/components/libretiny/gpio_arduino.cpp
+++ b/esphome/components/libretiny/gpio_arduino.cpp
@@ -63,10 +63,8 @@ void ArduinoInternalGPIOPin::pin_mode(gpio::Flags flags) {
   pinMode(pin_, flags_to_mode(flags));  // NOLINT
 }
 
-std::string ArduinoInternalGPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "%u", pin_);
-  return buffer;
+size_t ArduinoInternalGPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u", this->pin_);
 }
 
 bool ArduinoInternalGPIOPin::digital_read() {
diff --git a/esphome/components/libretiny/gpio_arduino.h b/esphome/components/libretiny/gpio_arduino.h
index 3674748c180..30c7c338697 100644
--- a/esphome/components/libretiny/gpio_arduino.h
+++ b/esphome/components/libretiny/gpio_arduino.h
@@ -16,7 +16,7 @@ class ArduinoInternalGPIOPin : public InternalGPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
   void detach_interrupt() const override;
   ISRInternalGPIOPin to_isr() const override;
   uint8_t get_pin() const override { return pin_; }
diff --git a/esphome/components/max6956/max6956.cpp b/esphome/components/max6956/max6956.cpp
index a377a1a192f..13fe5a53230 100644
--- a/esphome/components/max6956/max6956.cpp
+++ b/esphome/components/max6956/max6956.cpp
@@ -161,10 +161,8 @@ void MAX6956GPIOPin::setup() { pin_mode(flags_); }
 void MAX6956GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this->pin_, flags); }
 bool MAX6956GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void MAX6956GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
-std::string MAX6956GPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "%u via Max6956", pin_);
-  return buffer;
+size_t MAX6956GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via Max6956", this->pin_);
 }
 
 }  // namespace max6956
diff --git a/esphome/components/max6956/max6956.h b/esphome/components/max6956/max6956.h
index 0a1fd5e4b59..0c609b0b436 100644
--- a/esphome/components/max6956/max6956.h
+++ b/esphome/components/max6956/max6956.h
@@ -76,7 +76,7 @@ class MAX6956GPIOPin : public GPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_parent(MAX6956 *parent) { parent_ = parent; }
   void set_pin(uint8_t pin) { pin_ = pin; }
diff --git a/esphome/components/mcp23016/mcp23016.cpp b/esphome/components/mcp23016/mcp23016.cpp
index be86cb22569..87c26689625 100644
--- a/esphome/components/mcp23016/mcp23016.cpp
+++ b/esphome/components/mcp23016/mcp23016.cpp
@@ -99,10 +99,8 @@ void MCP23016GPIOPin::setup() { pin_mode(flags_); }
 void MCP23016GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this->pin_, flags); }
 bool MCP23016GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void MCP23016GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
-std::string MCP23016GPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "%u via MCP23016", pin_);
-  return buffer;
+size_t MCP23016GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via MCP23016", this->pin_);
 }
 
 }  // namespace mcp23016
diff --git a/esphome/components/mcp23016/mcp23016.h b/esphome/components/mcp23016/mcp23016.h
index 781c207de08..c2bc885c958 100644
--- a/esphome/components/mcp23016/mcp23016.h
+++ b/esphome/components/mcp23016/mcp23016.h
@@ -60,7 +60,7 @@ class MCP23016GPIOPin : public GPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_parent(MCP23016 *parent) { parent_ = parent; }
   void set_pin(uint8_t pin) { pin_ = pin; }
diff --git a/esphome/components/mcp23xxx_base/mcp23xxx_base.cpp b/esphome/components/mcp23xxx_base/mcp23xxx_base.cpp
index 81324e794fe..302f6b8280b 100644
--- a/esphome/components/mcp23xxx_base/mcp23xxx_base.cpp
+++ b/esphome/components/mcp23xxx_base/mcp23xxx_base.cpp
@@ -16,8 +16,8 @@ template<uint8_t N> bool MCP23XXXGPIOPin<N>::digital_read() {
 template<uint8_t N> void MCP23XXXGPIOPin<N>::digital_write(bool value) {
   this->parent_->digital_write(this->pin_, value != this->inverted_);
 }
-template<uint8_t N> std::string MCP23XXXGPIOPin<N>::dump_summary() const {
-  return str_snprintf("%u via MCP23XXX", 15, pin_);
+template<uint8_t N> size_t MCP23XXXGPIOPin<N>::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via MCP23XXX", this->pin_);
 }
 
 template class MCP23XXXGPIOPin<8>;
diff --git a/esphome/components/mcp23xxx_base/mcp23xxx_base.h b/esphome/components/mcp23xxx_base/mcp23xxx_base.h
index cf0ef5d41cc..fb992466d5d 100644
--- a/esphome/components/mcp23xxx_base/mcp23xxx_base.h
+++ b/esphome/components/mcp23xxx_base/mcp23xxx_base.h
@@ -36,7 +36,7 @@ template<uint8_t N> class MCP23XXXGPIOPin : public GPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_parent(MCP23XXXBase<N> *parent) { parent_ = parent; }
   void set_pin(uint8_t pin) { pin_ = pin; }
diff --git a/esphome/components/mpr121/mpr121.cpp b/esphome/components/mpr121/mpr121.cpp
index 5a8a8e7205f..4b358e384cc 100644
--- a/esphome/components/mpr121/mpr121.cpp
+++ b/esphome/components/mpr121/mpr121.cpp
@@ -153,10 +153,8 @@ void MPR121GPIOPin::digital_write(bool value) {
   this->parent_->digital_write(this->pin_ - 4, value != this->inverted_);
 }
 
-std::string MPR121GPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "ELE%u on MPR121", this->pin_);
-  return buffer;
+size_t MPR121GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "ELE%u on MPR121", this->pin_);
 }
 
 }  // namespace mpr121
diff --git a/esphome/components/mpr121/mpr121.h b/esphome/components/mpr121/mpr121.h
index 6dd2c383090..085018fff06 100644
--- a/esphome/components/mpr121/mpr121.h
+++ b/esphome/components/mpr121/mpr121.h
@@ -109,7 +109,7 @@ class MPR121GPIOPin : public GPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_parent(MPR121Component *parent) { this->parent_ = parent; }
   void set_pin(uint8_t pin) { this->pin_ = pin; }
diff --git a/esphome/components/pca6416a/pca6416a.cpp b/esphome/components/pca6416a/pca6416a.cpp
index c0056e780bb..909bac5f054 100644
--- a/esphome/components/pca6416a/pca6416a.cpp
+++ b/esphome/components/pca6416a/pca6416a.cpp
@@ -180,10 +180,8 @@ void PCA6416AGPIOPin::setup() { pin_mode(flags_); }
 void PCA6416AGPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this->pin_, flags); }
 bool PCA6416AGPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void PCA6416AGPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
-std::string PCA6416AGPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "%u via PCA6416A", pin_);
-  return buffer;
+size_t PCA6416AGPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via PCA6416A", this->pin_);
 }
 
 }  // namespace pca6416a
diff --git a/esphome/components/pca6416a/pca6416a.h b/esphome/components/pca6416a/pca6416a.h
index 10a4a64e9b0..138a51cc208 100644
--- a/esphome/components/pca6416a/pca6416a.h
+++ b/esphome/components/pca6416a/pca6416a.h
@@ -52,7 +52,7 @@ class PCA6416AGPIOPin : public GPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_parent(PCA6416AComponent *parent) { parent_ = parent; }
   void set_pin(uint8_t pin) { pin_ = pin; }
diff --git a/esphome/components/pca9554/pca9554.cpp b/esphome/components/pca9554/pca9554.cpp
index e8d49f66e2a..a6f9c2396c0 100644
--- a/esphome/components/pca9554/pca9554.cpp
+++ b/esphome/components/pca9554/pca9554.cpp
@@ -129,10 +129,8 @@ void PCA9554GPIOPin::setup() { pin_mode(flags_); }
 void PCA9554GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this->pin_, flags); }
 bool PCA9554GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void PCA9554GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
-std::string PCA9554GPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "%u via PCA9554", pin_);
-  return buffer;
+size_t PCA9554GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via PCA9554", this->pin_);
 }
 
 }  // namespace pca9554
diff --git a/esphome/components/pca9554/pca9554.h b/esphome/components/pca9554/pca9554.h
index 7b356b40688..bf752e50c99 100644
--- a/esphome/components/pca9554/pca9554.h
+++ b/esphome/components/pca9554/pca9554.h
@@ -59,7 +59,7 @@ class PCA9554GPIOPin : public GPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_parent(PCA9554Component *parent) { parent_ = parent; }
   void set_pin(uint8_t pin) { pin_ = pin; }
diff --git a/esphome/components/pcf8574/pcf8574.cpp b/esphome/components/pcf8574/pcf8574.cpp
index 72d8865d7fa..15418bfee5f 100644
--- a/esphome/components/pcf8574/pcf8574.cpp
+++ b/esphome/components/pcf8574/pcf8574.cpp
@@ -104,10 +104,8 @@ void PCF8574GPIOPin::setup() { pin_mode(flags_); }
 void PCF8574GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this->pin_, flags); }
 bool PCF8574GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void PCF8574GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
-std::string PCF8574GPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "%u via PCF8574", pin_);
-  return buffer;
+size_t PCF8574GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via PCF8574", this->pin_);
 }
 
 }  // namespace pcf8574
diff --git a/esphome/components/pcf8574/pcf8574.h b/esphome/components/pcf8574/pcf8574.h
index fd1ea8af633..5203030142c 100644
--- a/esphome/components/pcf8574/pcf8574.h
+++ b/esphome/components/pcf8574/pcf8574.h
@@ -54,7 +54,7 @@ class PCF8574GPIOPin : public GPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_parent(PCF8574Component *parent) { parent_ = parent; }
   void set_pin(uint8_t pin) { pin_ = pin; }
diff --git a/esphome/components/pi4ioe5v6408/pi4ioe5v6408.cpp b/esphome/components/pi4ioe5v6408/pi4ioe5v6408.cpp
index 517ca833e6d..f3a1f013d97 100644
--- a/esphome/components/pi4ioe5v6408/pi4ioe5v6408.cpp
+++ b/esphome/components/pi4ioe5v6408/pi4ioe5v6408.cpp
@@ -164,7 +164,9 @@ bool PI4IOE5V6408GPIOPin::digital_read() { return this->parent_->digital_read(th
 void PI4IOE5V6408GPIOPin::digital_write(bool value) {
   this->parent_->digital_write(this->pin_, value != this->inverted_);
 }
-std::string PI4IOE5V6408GPIOPin::dump_summary() const { return str_sprintf("%u via PI4IOE5V6408", this->pin_); }
+size_t PI4IOE5V6408GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via PI4IOE5V6408", this->pin_);
+}
 
 }  // namespace pi4ioe5v6408
 }  // namespace esphome
diff --git a/esphome/components/pi4ioe5v6408/pi4ioe5v6408.h b/esphome/components/pi4ioe5v6408/pi4ioe5v6408.h
index 82b3076fab8..4dc31201ce4 100644
--- a/esphome/components/pi4ioe5v6408/pi4ioe5v6408.h
+++ b/esphome/components/pi4ioe5v6408/pi4ioe5v6408.h
@@ -52,7 +52,7 @@ class PI4IOE5V6408GPIOPin : public GPIOPin, public Parented<PI4IOE5V6408Componen
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_pin(uint8_t pin) { this->pin_ = pin; }
   void set_inverted(bool inverted) { this->inverted_ = inverted; }
diff --git a/esphome/components/rp2040/gpio.cpp b/esphome/components/rp2040/gpio.cpp
index 3927815e466..2b1699f888a 100644
--- a/esphome/components/rp2040/gpio.cpp
+++ b/esphome/components/rp2040/gpio.cpp
@@ -64,10 +64,8 @@ void RP2040GPIOPin::pin_mode(gpio::Flags flags) {
   pinMode(pin_, flags_to_mode(flags, pin_));  // NOLINT
 }
 
-std::string RP2040GPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "GPIO%u", pin_);
-  return buffer;
+size_t RP2040GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "GPIO%u", this->pin_);
 }
 
 bool RP2040GPIOPin::digital_read() {
diff --git a/esphome/components/rp2040/gpio.h b/esphome/components/rp2040/gpio.h
index 47a6fe17f21..a98e1dab140 100644
--- a/esphome/components/rp2040/gpio.h
+++ b/esphome/components/rp2040/gpio.h
@@ -18,7 +18,7 @@ class RP2040GPIOPin : public InternalGPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
   void detach_interrupt() const override;
   ISRInternalGPIOPin to_isr() const override;
   uint8_t get_pin() const override { return pin_; }
diff --git a/esphome/components/sn74hc165/sn74hc165.cpp b/esphome/components/sn74hc165/sn74hc165.cpp
index 416d9db293d..718e0b86ed3 100644
--- a/esphome/components/sn74hc165/sn74hc165.cpp
+++ b/esphome/components/sn74hc165/sn74hc165.cpp
@@ -64,7 +64,9 @@ float SN74HC165Component::get_setup_priority() const { return setup_priority::IO
 
 bool SN74HC165GPIOPin::digital_read() { return this->parent_->digital_read_(this->pin_) != this->inverted_; }
 
-std::string SN74HC165GPIOPin::dump_summary() const { return str_snprintf("%u via SN74HC165", 18, pin_); }
+size_t SN74HC165GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via SN74HC165", this->pin_);
+}
 
 }  // namespace sn74hc165
 }  // namespace esphome
diff --git a/esphome/components/sn74hc165/sn74hc165.h b/esphome/components/sn74hc165/sn74hc165.h
index 4684844687a..5a3f3fe8ef0 100644
--- a/esphome/components/sn74hc165/sn74hc165.h
+++ b/esphome/components/sn74hc165/sn74hc165.h
@@ -47,7 +47,7 @@ class SN74HC165GPIOPin : public GPIOPin, public Parented<SN74HC165Component> {
   void pin_mode(gpio::Flags flags) override {}
   bool digital_read() override;
   void digital_write(bool value) override{};
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_pin(uint16_t pin) { pin_ = pin; }
   void set_inverted(bool inverted) { inverted_ = inverted; }
diff --git a/esphome/components/sn74hc595/sn74hc595.cpp b/esphome/components/sn74hc595/sn74hc595.cpp
index a9ada432e41..6b5c5d9fc4d 100644
--- a/esphome/components/sn74hc595/sn74hc595.cpp
+++ b/esphome/components/sn74hc595/sn74hc595.cpp
@@ -93,7 +93,9 @@ float SN74HC595Component::get_setup_priority() const { return setup_priority::IO
 void SN74HC595GPIOPin::digital_write(bool value) {
   this->parent_->digital_write_(this->pin_, value != this->inverted_);
 }
-std::string SN74HC595GPIOPin::dump_summary() const { return str_snprintf("%u via SN74HC595", 18, pin_); }
+size_t SN74HC595GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via SN74HC595", this->pin_);
+}
 
 }  // namespace sn74hc595
 }  // namespace esphome
diff --git a/esphome/components/sn74hc595/sn74hc595.h b/esphome/components/sn74hc595/sn74hc595.h
index 181015b1e6d..1cf70c86b50 100644
--- a/esphome/components/sn74hc595/sn74hc595.h
+++ b/esphome/components/sn74hc595/sn74hc595.h
@@ -54,7 +54,7 @@ class SN74HC595GPIOPin : public GPIOPin, public Parented<SN74HC595Component> {
   void pin_mode(gpio::Flags flags) override {}
   bool digital_read() override { return false; }
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_pin(uint16_t pin) { pin_ = pin; }
   void set_inverted(bool inverted) { inverted_ = inverted; }
diff --git a/esphome/components/spi/spi.cpp b/esphome/components/spi/spi.cpp
index c4876d1a747..36344a6d38d 100644
--- a/esphome/components/spi/spi.cpp
+++ b/esphome/components/spi/spi.cpp
@@ -64,9 +64,9 @@ void SPIComponent::setup() {
 
 void SPIComponent::dump_config() {
   ESP_LOGCONFIG(TAG, "SPI bus:");
-  LOG_PIN("  CLK Pin: ", this->clk_pin_)
-  LOG_PIN("  SDI Pin: ", this->sdi_pin_)
-  LOG_PIN("  SDO Pin: ", this->sdo_pin_)
+  LOG_PIN("  CLK Pin: ", this->clk_pin_);
+  LOG_PIN("  SDI Pin: ", this->sdi_pin_);
+  LOG_PIN("  SDO Pin: ", this->sdo_pin_);
   for (size_t i = 0; i != this->data_pins_.size(); i++) {
     ESP_LOGCONFIG(TAG, "  Data pin %u: GPIO%d", i, this->data_pins_[i]);
   }
diff --git a/esphome/components/spi/spi.h b/esphome/components/spi/spi.h
index 256cbcc65fd..e237cf44f45 100644
--- a/esphome/components/spi/spi.h
+++ b/esphome/components/spi/spi.h
@@ -120,7 +120,11 @@ class NullPin : public GPIOPin {
 
   void digital_write(bool value) override {}
 
-  std::string dump_summary() const override { return std::string(); }
+  size_t dump_summary(char *buffer, size_t len) const override {
+    if (len > 0)
+      buffer[0] = '\0';
+    return 0;
+  }
 
  protected:
   static GPIOPin *const NULL_PIN;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
diff --git a/esphome/components/sx1509/sx1509_gpio_pin.cpp b/esphome/components/sx1509/sx1509_gpio_pin.cpp
index a74c8b60b8b..41a99eba4ba 100644
--- a/esphome/components/sx1509/sx1509_gpio_pin.cpp
+++ b/esphome/components/sx1509/sx1509_gpio_pin.cpp
@@ -12,10 +12,8 @@ void SX1509GPIOPin::setup() { pin_mode(flags_); }
 void SX1509GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this->pin_, flags); }
 bool SX1509GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void SX1509GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
-std::string SX1509GPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "%u via sx1509", this->pin_);
-  return buffer;
+size_t SX1509GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via sx1509", this->pin_);
 }
 
 }  // namespace sx1509
diff --git a/esphome/components/sx1509/sx1509_gpio_pin.h b/esphome/components/sx1509/sx1509_gpio_pin.h
index eb9207e8822..5903af9d12a 100644
--- a/esphome/components/sx1509/sx1509_gpio_pin.h
+++ b/esphome/components/sx1509/sx1509_gpio_pin.h
@@ -13,7 +13,7 @@ class SX1509GPIOPin : public GPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_parent(SX1509Component *parent) { this->parent_ = parent; }
   void set_pin(uint8_t pin) { this->pin_ = pin; }
diff --git a/esphome/components/tca9555/tca9555.cpp b/esphome/components/tca9555/tca9555.cpp
index c3449ce2546..376de6a3708 100644
--- a/esphome/components/tca9555/tca9555.cpp
+++ b/esphome/components/tca9555/tca9555.cpp
@@ -138,7 +138,9 @@ void TCA9555GPIOPin::setup() { this->pin_mode(this->flags_); }
 void TCA9555GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this->pin_, flags); }
 bool TCA9555GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void TCA9555GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
-std::string TCA9555GPIOPin::dump_summary() const { return str_sprintf("%u via TCA9555", this->pin_); }
+size_t TCA9555GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via TCA9555", this->pin_);
+}
 
 }  // namespace tca9555
 }  // namespace esphome
diff --git a/esphome/components/tca9555/tca9555.h b/esphome/components/tca9555/tca9555.h
index 0c236ae4e3e..9f7273b1e7e 100644
--- a/esphome/components/tca9555/tca9555.h
+++ b/esphome/components/tca9555/tca9555.h
@@ -48,7 +48,7 @@ class TCA9555GPIOPin : public GPIOPin, public Parented<TCA9555Component> {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
 
   void set_pin(uint8_t pin) { this->pin_ = pin; }
   void set_inverted(bool inverted) { this->inverted_ = inverted; }
diff --git a/esphome/components/tee501/tee501.cpp b/esphome/components/tee501/tee501.cpp
index d6513dbbe00..06481b628b2 100644
--- a/esphome/components/tee501/tee501.cpp
+++ b/esphome/components/tee501/tee501.cpp
@@ -7,6 +7,8 @@ namespace tee501 {
 
 static const char *const TAG = "tee501";
 
+static constexpr size_t TEE501_SERIAL_NUMBER_SIZE = 7;
+
 void TEE501Component::setup() {
   uint8_t address[] = {0x70, 0x29};
   uint8_t identification[9];
@@ -17,7 +19,10 @@ void TEE501Component::setup() {
     this->mark_failed();
     return;
   }
-  ESP_LOGV(TAG, "    Serial Number: 0x%s", format_hex(identification + 0, 7).c_str());
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
+  char serial_hex[format_hex_size(TEE501_SERIAL_NUMBER_SIZE)];
+#endif
+  ESP_LOGV(TAG, "    Serial Number: 0x%s", format_hex_to(serial_hex, identification, TEE501_SERIAL_NUMBER_SIZE));
 }
 
 void TEE501Component::dump_config() {
diff --git a/esphome/components/uponor_smatrix/uponor_smatrix.cpp b/esphome/components/uponor_smatrix/uponor_smatrix.cpp
index 221f07c80e5..4c3a4b05dfa 100644
--- a/esphome/components/uponor_smatrix/uponor_smatrix.cpp
+++ b/esphome/components/uponor_smatrix/uponor_smatrix.cpp
@@ -8,6 +8,9 @@ namespace uponor_smatrix {
 
 static const char *const TAG = "uponor_smatrix";
 
+// Maximum bytes to log in verbose hex output
+static constexpr size_t UPONOR_MAX_LOG_BYTES = 36;
+
 void UponorSmatrixComponent::setup() {
 #ifdef USE_TIME
   if (this->time_id_ != nullptr) {
@@ -97,8 +100,11 @@ bool UponorSmatrixComponent::parse_byte_(uint8_t byte) {
     return false;
   }
 
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
+  char hex_buf[format_hex_size(UPONOR_MAX_LOG_BYTES)];
+#endif
   ESP_LOGV(TAG, "Received packet: addr=%08X, data=%s, crc=%04X", device_address,
-           format_hex(&packet[4], packet_len - 6).c_str(), crc);
+           format_hex_to(hex_buf, &packet[4], packet_len - 6), crc);
 
   // Handle packet
   size_t data_len = (packet_len - 6) / 3;
diff --git a/esphome/components/vbus/vbus.cpp b/esphome/components/vbus/vbus.cpp
index e474dcfe176..b9496a08dec 100644
--- a/esphome/components/vbus/vbus.cpp
+++ b/esphome/components/vbus/vbus.cpp
@@ -8,6 +8,9 @@ namespace vbus {
 
 static const char *const TAG = "vbus";
 
+// Maximum bytes to log in verbose hex output (16 frames * 4 bytes = 64 bytes typical)
+static constexpr size_t VBUS_MAX_LOG_BYTES = 64;
+
 void VBus::dump_config() {
   ESP_LOGCONFIG(TAG, "VBus:");
   check_uart_settings(9600);
@@ -101,8 +104,11 @@ void VBus::loop() {
         this->buffer_.push_back(this->fbytes_[i]);
       if (++this->cframe_ < this->frames_)
         continue;
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
+      char hex_buf[format_hex_size(VBUS_MAX_LOG_BYTES)];
+#endif
       ESP_LOGV(TAG, "P2 C%04x %04x->%04x: %s", this->command_, this->source_, this->dest_,
-               format_hex(this->buffer_).c_str());
+               format_hex_to(hex_buf, this->buffer_.data(), this->buffer_.size()));
       for (auto &listener : this->listeners_)
         listener->on_message(this->command_, this->source_, this->dest_, this->buffer_);
       this->state_ = 0;
diff --git a/esphome/components/voice_assistant/__init__.py b/esphome/components/voice_assistant/__init__.py
index 59c7ec8383a..d28c786dd80 100644
--- a/esphome/components/voice_assistant/__init__.py
+++ b/esphome/components/voice_assistant/__init__.py
@@ -11,6 +11,7 @@ from esphome.const import (
     CONF_ON_CLIENT_DISCONNECTED,
     CONF_ON_ERROR,
     CONF_ON_IDLE,
+    CONF_ON_START,
     CONF_SPEAKER,
 )
 
@@ -24,7 +25,6 @@ CONF_ON_INTENT_END = "on_intent_end"
 CONF_ON_INTENT_PROGRESS = "on_intent_progress"
 CONF_ON_INTENT_START = "on_intent_start"
 CONF_ON_LISTENING = "on_listening"
-CONF_ON_START = "on_start"
 CONF_ON_STT_END = "on_stt_end"
 CONF_ON_STT_VAD_END = "on_stt_vad_end"
 CONF_ON_STT_VAD_START = "on_stt_vad_start"
diff --git a/esphome/components/waveshare_epaper/waveshare_213v3.cpp b/esphome/components/waveshare_epaper/waveshare_213v3.cpp
index 068cb91d313..b55f3c8d26d 100644
--- a/esphome/components/waveshare_epaper/waveshare_213v3.cpp
+++ b/esphome/components/waveshare_epaper/waveshare_213v3.cpp
@@ -177,10 +177,10 @@ uint32_t WaveshareEPaper2P13InV3::idle_timeout_() { return 5000; }
 void WaveshareEPaper2P13InV3::dump_config() {
   LOG_DISPLAY("", "Waveshare E-Paper", this)
   ESP_LOGCONFIG(TAG, "  Model: 2.13inV3");
-  LOG_PIN("  CS Pin: ", this->cs_)
-  LOG_PIN("  Reset Pin: ", this->reset_pin_)
-  LOG_PIN("  DC Pin: ", this->dc_pin_)
-  LOG_PIN("  Busy Pin: ", this->busy_pin_)
+  LOG_PIN("  CS Pin: ", this->cs_);
+  LOG_PIN("  Reset Pin: ", this->reset_pin_);
+  LOG_PIN("  DC Pin: ", this->dc_pin_);
+  LOG_PIN("  Busy Pin: ", this->busy_pin_);
   LOG_UPDATE_INTERVAL(this);
 }
 
diff --git a/esphome/components/weikai/weikai.cpp b/esphome/components/weikai/weikai.cpp
index ebe987cc65e..3384a0572f1 100644
--- a/esphome/components/weikai/weikai.cpp
+++ b/esphome/components/weikai/weikai.cpp
@@ -245,10 +245,8 @@ void WeikaiGPIOPin::setup() {
   this->pin_mode(this->flags_);
 }
 
-std::string WeikaiGPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "%u via WeiKai %s", this->pin_, this->parent_->get_name());
-  return buffer;
+size_t WeikaiGPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via WeiKai %s", this->pin_, this->parent_->get_name());
 }
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/esphome/components/weikai/weikai.h b/esphome/components/weikai/weikai.h
index 987278213ad..a27c14106d5 100644
--- a/esphome/components/weikai/weikai.h
+++ b/esphome/components/weikai/weikai.h
@@ -278,7 +278,7 @@ class WeikaiGPIOPin : public GPIOPin {
   gpio::Flags get_flags() const override { return this->flags_; }
 
   void setup() override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
   void pin_mode(gpio::Flags flags) override { this->parent_->set_pin_direction_(this->pin_, flags); }
   bool digital_read() override { return this->parent_->read_pin_val_(this->pin_) != this->inverted_; }
   void digital_write(bool value) override { this->parent_->write_pin_val_(this->pin_, value != this->inverted_); }
diff --git a/esphome/components/xiaomi_ble/xiaomi_ble.cpp b/esphome/components/xiaomi_ble/xiaomi_ble.cpp
index 564870d74e9..9f250631330 100644
--- a/esphome/components/xiaomi_ble/xiaomi_ble.cpp
+++ b/esphome/components/xiaomi_ble/xiaomi_ble.cpp
@@ -12,6 +12,9 @@ namespace xiaomi_ble {
 
 static const char *const TAG = "xiaomi_ble";
 
+// Maximum bytes to log in very verbose hex output (covers largest packet of ~24 bytes)
+static constexpr size_t XIAOMI_MAX_LOG_BYTES = 32;
+
 bool parse_xiaomi_value(uint16_t value_type, const uint8_t *data, uint8_t value_length, XiaomiParseResult &result) {
   // button pressed, 3 bytes, only byte 3 is used for supported devices so far
   if ((value_type == 0x1001) && (value_length == 3)) {
@@ -263,7 +266,10 @@ optional<XiaomiParseResult> parse_xiaomi_header(const esp32_ble_tracker::Service
 bool decrypt_xiaomi_payload(std::vector<uint8_t> &raw, const uint8_t *bindkey, const uint64_t &address) {
   if ((raw.size() != 19) && ((raw.size() < 22) || (raw.size() > 24))) {
     ESP_LOGVV(TAG, "decrypt_xiaomi_payload(): data packet has wrong size (%d)!", raw.size());
-    ESP_LOGVV(TAG, "  Packet : %s", format_hex_pretty(raw.data(), raw.size()).c_str());
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERY_VERBOSE
+    char hex_buf[format_hex_pretty_size(XIAOMI_MAX_LOG_BYTES)];
+#endif
+    ESP_LOGVV(TAG, "  Packet : %s", format_hex_pretty_to(hex_buf, raw.data(), raw.size()));
     return false;
   }
 
@@ -320,12 +326,17 @@ bool decrypt_xiaomi_payload(std::vector<uint8_t> &raw, const uint8_t *bindkey, c
     memcpy(mac_address + 4, mac_reverse + 1, 1);
     memcpy(mac_address + 5, mac_reverse, 1);
     ESP_LOGVV(TAG, "decrypt_xiaomi_payload(): authenticated decryption failed.");
-    ESP_LOGVV(TAG, "  MAC address : %s", format_mac_address_pretty(mac_address).c_str());
-    ESP_LOGVV(TAG, "       Packet : %s", format_hex_pretty(raw.data(), raw.size()).c_str());
-    ESP_LOGVV(TAG, "          Key : %s", format_hex_pretty(vector.key, vector.keysize).c_str());
-    ESP_LOGVV(TAG, "           Iv : %s", format_hex_pretty(vector.iv, vector.ivsize).c_str());
-    ESP_LOGVV(TAG, "       Cipher : %s", format_hex_pretty(vector.ciphertext, vector.datasize).c_str());
-    ESP_LOGVV(TAG, "          Tag : %s", format_hex_pretty(vector.tag, vector.tagsize).c_str());
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERY_VERBOSE
+    char mac_buf[MAC_ADDRESS_PRETTY_BUFFER_SIZE];
+    format_mac_addr_upper(mac_address, mac_buf);
+    char hex_buf[format_hex_pretty_size(XIAOMI_MAX_LOG_BYTES)];
+#endif
+    ESP_LOGVV(TAG, "  MAC address : %s", mac_buf);
+    ESP_LOGVV(TAG, "       Packet : %s", format_hex_pretty_to(hex_buf, raw.data(), raw.size()));
+    ESP_LOGVV(TAG, "          Key : %s", format_hex_pretty_to(hex_buf, vector.key, vector.keysize));
+    ESP_LOGVV(TAG, "           Iv : %s", format_hex_pretty_to(hex_buf, vector.iv, vector.ivsize));
+    ESP_LOGVV(TAG, "       Cipher : %s", format_hex_pretty_to(hex_buf, vector.ciphertext, vector.datasize));
+    ESP_LOGVV(TAG, "          Tag : %s", format_hex_pretty_to(hex_buf, vector.tag, vector.tagsize));
     mbedtls_ccm_free(&ctx);
     return false;
   }
@@ -341,8 +352,11 @@ bool decrypt_xiaomi_payload(std::vector<uint8_t> &raw, const uint8_t *bindkey, c
   raw[0] &= ~0x08;
 
   ESP_LOGVV(TAG, "decrypt_xiaomi_payload(): authenticated decryption passed.");
-  ESP_LOGVV(TAG, "  Plaintext : %s, Packet : %d", format_hex_pretty(raw.data() + cipher_pos, vector.datasize).c_str(),
-            static_cast<int>(raw[4]));
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERY_VERBOSE
+  char hex_buf[format_hex_pretty_size(XIAOMI_MAX_LOG_BYTES)];
+#endif
+  ESP_LOGVV(TAG, "  Plaintext : %s, Packet : %d",
+            format_hex_pretty_to(hex_buf, raw.data() + cipher_pos, vector.datasize), static_cast<int>(raw[4]));
 
   mbedtls_ccm_free(&ctx);
   return true;
diff --git a/esphome/components/xl9535/xl9535.cpp b/esphome/components/xl9535/xl9535.cpp
index 958fc5eede4..dd6c8188ebd 100644
--- a/esphome/components/xl9535/xl9535.cpp
+++ b/esphome/components/xl9535/xl9535.cpp
@@ -110,7 +110,9 @@ void XL9535Component::pin_mode(uint8_t pin, gpio::Flags mode) {
 
 void XL9535GPIOPin::setup() { this->pin_mode(this->flags_); }
 
-std::string XL9535GPIOPin::dump_summary() const { return str_snprintf("%u via XL9535", 15, this->pin_); }
+size_t XL9535GPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "%u via XL9535", this->pin_);
+}
 
 void XL9535GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this->pin_, flags); }
 bool XL9535GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
diff --git a/esphome/components/xl9535/xl9535.h b/esphome/components/xl9535/xl9535.h
index 3b511fd9b3a..be0e2fbd820 100644
--- a/esphome/components/xl9535/xl9535.h
+++ b/esphome/components/xl9535/xl9535.h
@@ -39,7 +39,7 @@ class XL9535GPIOPin : public GPIOPin {
   gpio::Flags get_flags() const override { return this->flags_; }
 
   void setup() override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
diff --git a/esphome/components/zephyr/gpio.cpp b/esphome/components/zephyr/gpio.cpp
index 41b983535c0..8041c361cc1 100644
--- a/esphome/components/zephyr/gpio.cpp
+++ b/esphome/components/zephyr/gpio.cpp
@@ -85,10 +85,8 @@ void ZephyrGPIOPin::pin_mode(gpio::Flags flags) {
   }
 }
 
-std::string ZephyrGPIOPin::dump_summary() const {
-  char buffer[32];
-  snprintf(buffer, sizeof(buffer), "GPIO%u, P%u.%u", this->pin_, this->pin_ / 32, this->pin_ % 32);
-  return buffer;
+size_t ZephyrGPIOPin::dump_summary(char *buffer, size_t len) const {
+  return snprintf(buffer, len, "GPIO%u, P%u.%u", this->pin_, this->pin_ / 32, this->pin_ % 32);
 }
 
 bool ZephyrGPIOPin::digital_read() {
diff --git a/esphome/components/zephyr/gpio.h b/esphome/components/zephyr/gpio.h
index 6e8f81857a2..b405f385bcd 100644
--- a/esphome/components/zephyr/gpio.h
+++ b/esphome/components/zephyr/gpio.h
@@ -16,7 +16,7 @@ class ZephyrGPIOPin : public InternalGPIOPin {
   void pin_mode(gpio::Flags flags) override;
   bool digital_read() override;
   void digital_write(bool value) override;
-  std::string dump_summary() const override;
+  size_t dump_summary(char *buffer, size_t len) const override;
   void detach_interrupt() const override;
   ISRInternalGPIOPin to_isr() const override;
   uint8_t get_pin() const override { return this->pin_; }
diff --git a/esphome/const.py b/esphome/const.py
index 1d46e81f9d1..518247aa60b 100644
--- a/esphome/const.py
+++ b/esphome/const.py
@@ -710,6 +710,7 @@ CONF_ON_RELEASE = "on_release"
 CONF_ON_RESPONSE = "on_response"
 CONF_ON_SHUTDOWN = "on_shutdown"
 CONF_ON_SPEED_SET = "on_speed_set"
+CONF_ON_START = "on_start"
 CONF_ON_STATE = "on_state"
 CONF_ON_SUCCESS = "on_success"
 CONF_ON_TAG = "on_tag"
diff --git a/esphome/core/entity_base.cpp b/esphome/core/entity_base.cpp
index b7616a9ad38..8508b93411a 100644
--- a/esphome/core/entity_base.cpp
+++ b/esphome/core/entity_base.cpp
@@ -9,7 +9,8 @@ static const char *const TAG = "entity_base";
 
 // Entity Name
 const StringRef &EntityBase::get_name() const { return this->name_; }
-void EntityBase::set_name(const char *name) {
+void EntityBase::set_name(const char *name) { this->set_name(name, 0); }
+void EntityBase::set_name(const char *name, uint32_t object_id_hash) {
   this->name_ = StringRef(name);
   if (this->name_.empty()) {
 #ifdef USE_DEVICES
@@ -18,11 +19,29 @@ void EntityBase::set_name(const char *name) {
     } else
 #endif
     {
-      this->name_ = StringRef(App.get_friendly_name());
+      // Bug-for-bug compatibility with OLD behavior:
+      // - With MAC suffix: OLD code used App.get_friendly_name() directly (no fallback)
+      // - Without MAC suffix: OLD code used pre-computed object_id with fallback to device name
+      const std::string &friendly = App.get_friendly_name();
+      if (App.is_name_add_mac_suffix_enabled()) {
+        // MAC suffix enabled - use friendly_name directly (even if empty) for compatibility
+        this->name_ = StringRef(friendly);
+      } else {
+        // No MAC suffix - fallback to device name if friendly_name is empty
+        this->name_ = StringRef(!friendly.empty() ? friendly : App.get_name());
+      }
     }
     this->flags_.has_own_name = false;
+    // Dynamic name - must calculate hash at runtime
+    this->calc_object_id_();
   } else {
     this->flags_.has_own_name = true;
+    // Static name - use pre-computed hash if provided
+    if (object_id_hash != 0) {
+      this->object_id_hash_ = object_id_hash;
+    } else {
+      this->calc_object_id_();
+    }
   }
 }
 
@@ -45,69 +64,30 @@ void EntityBase::set_icon(const char *icon) {
 #endif
 }
 
-// Check if the object_id is dynamic (changes with MAC suffix)
-bool EntityBase::is_object_id_dynamic_() const {
-  return !this->flags_.has_own_name && App.is_name_add_mac_suffix_enabled();
-}
-
-// Entity Object ID
+// Entity Object ID - computed on-demand from name
 std::string EntityBase::get_object_id() const {
-  // Check if `App.get_friendly_name()` is constant or dynamic.
-  if (this->is_object_id_dynamic_()) {
-    // `App.get_friendly_name()` is dynamic.
-    return str_sanitize(str_snake_case(App.get_friendly_name()));
-  }
-  // `App.get_friendly_name()` is constant.
-  return this->object_id_c_str_ == nullptr ? "" : this->object_id_c_str_;
-}
-void EntityBase::set_object_id(const char *object_id) {
-  this->object_id_c_str_ = object_id;
-  this->calc_object_id_();
-}
-
-void EntityBase::set_name_and_object_id(const char *name, const char *object_id) {
-  this->set_name(name);
-  this->object_id_c_str_ = object_id;
-  this->calc_object_id_();
-}
-
-// Calculate Object ID Hash from Entity Name
-void EntityBase::calc_object_id_() {
   char buf[OBJECT_ID_MAX_LEN];
-  StringRef object_id = this->get_object_id_to(buf);
-  this->object_id_hash_ = fnv1_hash(object_id.c_str());
+  size_t len = this->write_object_id_to(buf, sizeof(buf));
+  return std::string(buf, len);
 }
 
-// Format dynamic object_id: sanitized snake_case of friendly_name
-static size_t format_dynamic_object_id(char *buf, size_t buf_size) {
-  const std::string &name = App.get_friendly_name();
-  size_t len = std::min(name.size(), buf_size - 1);
-  for (size_t i = 0; i < len; i++) {
-    buf[i] = to_sanitized_char(to_snake_case_char(name[i]));
-  }
-  buf[len] = '\0';
-  return len;
+// Calculate Object ID Hash directly from name using snake_case + sanitize
+void EntityBase::calc_object_id_() {
+  this->object_id_hash_ = fnv1_hash_object_id(this->name_.c_str(), this->name_.size());
 }
 
 size_t EntityBase::write_object_id_to(char *buf, size_t buf_size) const {
-  if (this->is_object_id_dynamic_()) {
-    return format_dynamic_object_id(buf, buf_size);
+  size_t len = std::min(this->name_.size(), buf_size - 1);
+  for (size_t i = 0; i < len; i++) {
+    buf[i] = to_sanitized_char(to_snake_case_char(this->name_[i]));
   }
-  const char *src = this->object_id_c_str_ == nullptr ? "" : this->object_id_c_str_;
-  size_t len = strlen(src);
-  if (len >= buf_size)
-    len = buf_size - 1;
-  memcpy(buf, src, len);
   buf[len] = '\0';
   return len;
 }
 
 StringRef EntityBase::get_object_id_to(std::span<char, OBJECT_ID_MAX_LEN> buf) const {
-  if (this->is_object_id_dynamic_()) {
-    size_t len = format_dynamic_object_id(buf.data(), buf.size());
-    return StringRef(buf.data(), len);
-  }
-  return this->object_id_c_str_ == nullptr ? StringRef() : StringRef(this->object_id_c_str_);
+  size_t len = this->write_object_id_to(buf.data(), buf.size());
+  return StringRef(buf.data(), len);
 }
 
 uint32_t EntityBase::get_object_id_hash() { return this->object_id_hash_; }
diff --git a/esphome/core/entity_base.h b/esphome/core/entity_base.h
index a5c69f132cc..a45c7795bf0 100644
--- a/esphome/core/entity_base.h
+++ b/esphome/core/entity_base.h
@@ -28,6 +28,9 @@ class EntityBase {
   // Get/set the name of this Entity
   const StringRef &get_name() const;
   void set_name(const char *name);
+  /// Set name with pre-computed object_id hash (avoids runtime hash calculation)
+  /// Use hash=0 for dynamic names that need runtime calculation
+  void set_name(const char *name, uint32_t object_id_hash);
 
   // Get whether this Entity has its own name or it should use the device friendly_name.
   bool has_own_name() const { return this->flags_.has_own_name; }
@@ -43,10 +46,6 @@ class EntityBase {
                 "which will remain available longer. get_object_id() will be removed in 2026.7.0",
                 "2025.12.0")
   std::string get_object_id() const;
-  void set_object_id(const char *object_id);
-
-  // Set both name and object_id in one call (reduces generated code size)
-  void set_name_and_object_id(const char *name, const char *object_id);
 
   // Get the unique Object ID of this Entity
   uint32_t get_object_id_hash();
@@ -142,11 +141,7 @@ class EntityBase {
  protected:
   void calc_object_id_();
 
-  /// Check if the object_id is dynamic (changes with MAC suffix)
-  bool is_object_id_dynamic_() const;
-
   StringRef name_;
-  const char *object_id_c_str_{nullptr};
 #ifdef USE_ENTITY_ICON
   const char *icon_c_str_{nullptr};
 #endif
diff --git a/esphome/core/entity_helpers.py b/esphome/core/entity_helpers.py
index f360b4d809e..c1801c0bdaa 100644
--- a/esphome/core/entity_helpers.py
+++ b/esphome/core/entity_helpers.py
@@ -15,7 +15,7 @@ from esphome.const import (
 from esphome.core import CORE, ID
 from esphome.cpp_generator import MockObj, add, get_variable
 import esphome.final_validate as fv
-from esphome.helpers import sanitize, snake_case
+from esphome.helpers import fnv1_hash_object_id, sanitize, snake_case
 from esphome.types import ConfigType, EntityMetadata
 
 _LOGGER = logging.getLogger(__name__)
@@ -75,34 +75,18 @@ async def setup_entity(var: MockObj, config: ConfigType, platform: str) -> None:
         config: Configuration dictionary containing entity settings
         platform: The platform name (e.g., "sensor", "binary_sensor")
     """
-    # Get device info
-    device_name: str | None = None
-    device_id_obj: ID | None
+    # Get device info if configured
     if device_id_obj := config.get(CONF_DEVICE_ID):
         device: MockObj = await get_variable(device_id_obj)
         add(var.set_device(device))
-        # Get device name for object ID calculation
-        device_name = device_id_obj.id
 
-    # Calculate base object_id using the same logic as C++
-    # This must match the C++ behavior in esphome/core/entity_base.cpp
-    base_object_id = get_base_entity_object_id(
-        config[CONF_NAME], CORE.friendly_name, device_name
-    )
-
-    if not config[CONF_NAME]:
-        _LOGGER.debug(
-            "Entity has empty name, using '%s' as object_id base", base_object_id
-        )
-
-    # Set both name and object_id in one call to reduce generated code size
-    add(var.set_name_and_object_id(config[CONF_NAME], base_object_id))
-    _LOGGER.debug(
-        "Setting object_id '%s' for entity '%s' on platform '%s'",
-        base_object_id,
-        config[CONF_NAME],
-        platform,
-    )
+    # Set the entity name with pre-computed object_id hash
+    # For named entities: pre-compute hash from entity name
+    # For empty-name entities: pass 0, C++ calculates hash at runtime from
+    # device name, friendly_name, or app name (bug-for-bug compatibility)
+    entity_name = config[CONF_NAME]
+    object_id_hash = fnv1_hash_object_id(entity_name) if entity_name else 0
+    add(var.set_name(entity_name, object_id_hash))
     # Only set disabled_by_default if True (default is False)
     if config[CONF_DISABLED_BY_DEFAULT]:
         add(var.set_disabled_by_default(True))
diff --git a/esphome/core/gpio.cpp b/esphome/core/gpio.cpp
new file mode 100644
index 00000000000..21e88b5b6d8
--- /dev/null
+++ b/esphome/core/gpio.cpp
@@ -0,0 +1,24 @@
+#include "esphome/core/gpio.h"
+#include "esphome/core/log.h"
+
+namespace esphome {
+
+#ifdef USE_ESP8266
+void log_pin(const char *tag, const __FlashStringHelper *prefix, GPIOPin *pin) {
+  if (pin == nullptr)
+    return;
+  static constexpr size_t LOG_PIN_PREFIX_MAX_LEN = 32;
+  char prefix_buf[LOG_PIN_PREFIX_MAX_LEN];
+  strncpy_P(prefix_buf, reinterpret_cast<const char *>(prefix), sizeof(prefix_buf) - 1);
+  prefix_buf[sizeof(prefix_buf) - 1] = '\0';
+  log_pin_with_prefix(tag, prefix_buf, pin);
+}
+#else
+void log_pin(const char *tag, const char *prefix, GPIOPin *pin) {
+  if (pin == nullptr)
+    return;
+  log_pin_with_prefix(tag, prefix, pin);
+}
+#endif
+
+}  // namespace esphome
diff --git a/esphome/core/gpio.h b/esphome/core/gpio.h
index dd6f14fef93..f2f85e18bc9 100644
--- a/esphome/core/gpio.h
+++ b/esphome/core/gpio.h
@@ -1,13 +1,22 @@
 #pragma once
+#include <algorithm>
 #include <cstdint>
+#include <cstring>
 #include <string>
 
+#include "esphome/core/helpers.h"
+#include "esphome/core/log.h"
+
 namespace esphome {
 
-#define LOG_PIN(prefix, pin) \
-  if ((pin) != nullptr) { \
-    ESP_LOGCONFIG(TAG, prefix "%s", (pin)->dump_summary().c_str()); \
-  }
+/// Maximum buffer size for dump_summary output
+inline constexpr size_t GPIO_SUMMARY_MAX_LEN = 48;
+
+#ifdef USE_ESP8266
+#define LOG_PIN(prefix, pin) log_pin(TAG, F(prefix), pin)
+#else
+#define LOG_PIN(prefix, pin) log_pin(TAG, prefix, pin)
+#endif
 
 // put GPIO flags in a namespace to not pollute esphome namespace
 namespace gpio {
@@ -64,7 +73,17 @@ class GPIOPin {
 
   virtual void digital_write(bool value) = 0;
 
-  virtual std::string dump_summary() const = 0;
+  /// Write a summary of this pin to the provided buffer.
+  /// @param buffer The buffer to write to
+  /// @param len The size of the buffer (must be > 0)
+  /// @return The number of characters that would be written (excluding null terminator),
+  ///         which may exceed len-1 if truncation occurred (snprintf semantics)
+  virtual size_t dump_summary(char *buffer, size_t len) const;
+
+  /// Get a summary of this pin as a string.
+  /// @deprecated Use dump_summary(char*, size_t) instead. Will be removed in 2026.7.0.
+  ESPDEPRECATED("Override dump_summary(char*, size_t) instead. Will be removed in 2026.7.0.", "2026.1.0")
+  virtual std::string dump_summary() const;
 
   virtual bool is_internal() { return false; }
 };
@@ -103,4 +122,41 @@ class InternalGPIOPin : public GPIOPin {
   virtual void attach_interrupt(void (*func)(void *), void *arg, gpio::InterruptType type) const = 0;
 };
 
+// Inline default implementations for GPIOPin virtual methods.
+// These provide bridge functionality for backwards compatibility with external components.
+
+// Default implementation bridges to old std::string method for backwards compatibility.
+inline size_t GPIOPin::dump_summary(char *buffer, size_t len) const {
+  if (len == 0)
+    return 0;
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+  std::string s = this->dump_summary();
+#pragma GCC diagnostic pop
+  size_t copy_len = std::min(s.size(), len - 1);
+  memcpy(buffer, s.c_str(), copy_len);
+  buffer[copy_len] = '\0';
+  return s.size();  // Return would-be length (snprintf semantics)
+}
+
+// Default implementation returns empty string.
+// External components should override this if they haven't migrated to buffer-based version.
+// Remove before 2026.7.0
+inline std::string GPIOPin::dump_summary() const { return {}; }
+
+// Inline helper for log_pin - allows compiler to inline into log_pin in gpio.cpp
+inline void log_pin_with_prefix(const char *tag, const char *prefix, GPIOPin *pin) {
+  char buffer[GPIO_SUMMARY_MAX_LEN];
+  size_t len = pin->dump_summary(buffer, sizeof(buffer));
+  len = std::min(len, sizeof(buffer) - 1);
+  esp_log_printf_(ESPHOME_LOG_LEVEL_CONFIG, tag, __LINE__, "%s%.*s", prefix, (int) len, buffer);
+}
+
+// log_pin function declarations - implementation in gpio.cpp
+#ifdef USE_ESP8266
+void log_pin(const char *tag, const __FlashStringHelper *prefix, GPIOPin *pin);
+#else
+void log_pin(const char *tag, const char *prefix, GPIOPin *pin);
+#endif
+
 }  // namespace esphome
diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index ac7a96a8c8e..f7a14ed2ec9 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -529,6 +529,20 @@ constexpr char to_sanitized_char(char c) {
 /// Sanitizes the input string by removing all characters but alphanumerics, dashes and underscores.
 std::string str_sanitize(const std::string &str);
 
+/// Calculate FNV-1 hash of a string while applying snake_case + sanitize transformations.
+/// This computes object_id hashes directly from names without creating an intermediate buffer.
+/// IMPORTANT: Must match Python fnv1_hash_object_id() in esphome/helpers.py.
+/// If you modify this function, update the Python version and tests in both places.
+inline uint32_t fnv1_hash_object_id(const char *str, size_t len) {
+  uint32_t hash = FNV1_OFFSET_BASIS;
+  for (size_t i = 0; i < len; i++) {
+    hash *= FNV1_PRIME;
+    // Apply snake_case (space->underscore, uppercase->lowercase) then sanitize
+    hash ^= static_cast<uint8_t>(to_sanitized_char(to_snake_case_char(str[i])));
+  }
+  return hash;
+}
+
 /// snprintf-like function returning std::string of maximum length \p len (excluding null terminator).
 std::string __attribute__((format(printf, 1, 3))) str_snprintf(const char *fmt, size_t len, ...);
 
diff --git a/esphome/helpers.py b/esphome/helpers.py
index d1623d1d3c5..ae142b7f8be 100644
--- a/esphome/helpers.py
+++ b/esphome/helpers.py
@@ -35,6 +35,10 @@ IS_MACOS = platform.system() == "Darwin"
 IS_WINDOWS = platform.system() == "Windows"
 IS_LINUX = platform.system() == "Linux"
 
+# FNV-1 hash constants (must match C++ in esphome/core/helpers.h)
+FNV1_OFFSET_BASIS = 2166136261
+FNV1_PRIME = 16777619
+
 
 def ensure_unique_string(preferred_string, current_strings):
     test_string = preferred_string
@@ -49,8 +53,17 @@ def ensure_unique_string(preferred_string, current_strings):
     return test_string
 
 
+def fnv1_hash(string: str) -> int:
+    """FNV-1 32-bit hash function (multiply then XOR)."""
+    hash_value = FNV1_OFFSET_BASIS
+    for char in string:
+        hash_value = (hash_value * FNV1_PRIME) & 0xFFFFFFFF
+        hash_value ^= ord(char)
+    return hash_value
+
+
 def fnv1a_32bit_hash(string: str) -> int:
-    """FNV-1a 32-bit hash function.
+    """FNV-1a 32-bit hash function (XOR then multiply).
 
     Note: This uses 32-bit hash instead of 64-bit for several reasons:
     1. ESPHome targets 32-bit microcontrollers with limited RAM (often <320KB)
@@ -63,13 +76,22 @@ def fnv1a_32bit_hash(string: str) -> int:
     a handful of area_ids and device_ids (typically <10 areas and <100
     devices), making collisions virtually impossible.
     """
-    hash_value = 2166136261
+    hash_value = FNV1_OFFSET_BASIS
     for char in string:
         hash_value ^= ord(char)
-        hash_value = (hash_value * 16777619) & 0xFFFFFFFF
+        hash_value = (hash_value * FNV1_PRIME) & 0xFFFFFFFF
     return hash_value
 
 
+def fnv1_hash_object_id(name: str) -> int:
+    """Compute FNV-1 hash of name with snake_case + sanitize transformations.
+
+    IMPORTANT: Must produce same result as C++ fnv1_hash_object_id() in helpers.h.
+    Used for pre-computing entity object_id hashes at code generation time.
+    """
+    return fnv1_hash(sanitize(snake_case(name)))
+
+
 def strip_accents(value: str) -> str:
     """Remove accents from a string."""
     import unicodedata
diff --git a/requirements.txt b/requirements.txt
index d457be9cd24..833ccbb0ed4 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -12,10 +12,10 @@ platformio==6.1.18  # When updating platformio, also update /docker/Dockerfile
 esptool==5.1.0
 click==8.1.7
 esphome-dashboard==20251013.0
-aioesphomeapi==43.9.1
+aioesphomeapi==43.10.0
 zeroconf==0.148.0
 puremagic==1.30
-ruamel.yaml==0.18.17 # dashboard_import
+ruamel.yaml==0.19.1 # dashboard_import
 ruamel.yaml.clib==0.2.15 # dashboard_import
 esphome-glyphsets==0.2.0
 pillow==11.3.0
diff --git a/script/api_protobuf/api_protobuf.py b/script/api_protobuf/api_protobuf.py
index 5b68c6a3d2f..7293f2abbc8 100755
--- a/script/api_protobuf/api_protobuf.py
+++ b/script/api_protobuf/api_protobuf.py
@@ -362,12 +362,12 @@ def create_field_type_info(
             # Traditional fixed array approach with copy (takes priority)
             return FixedArrayBytesType(field, fixed_size)
 
-        # For SOURCE_CLIENT only messages (decode but no encode), use pointer
+        # For messages that decode (SOURCE_CLIENT or SOURCE_BOTH), use pointer
         # for zero-copy access to the receive buffer
-        if needs_decode and not needs_encode:
+        if needs_decode:
             return PointerToBytesBufferType(field, None)
 
-        # For SOURCE_BOTH/SOURCE_SERVER, explicit annotation is still needed
+        # For SOURCE_SERVER (encode only), explicit annotation is still needed
         if get_field_opt(field, pb.pointer_to_buffer, False):
             return PointerToBytesBufferType(field, None)
 
diff --git a/script/ci-custom.py b/script/ci-custom.py
index 609d89403f3..f0676d594b8 100755
--- a/script/ci-custom.py
+++ b/script/ci-custom.py
@@ -552,6 +552,8 @@ def convert_path_to_relative(abspath, current):
     exclude=[
         "esphome/components/libretiny/generate_components.py",
         "esphome/components/web_server/__init__.py",
+        # const.py has absolute import in docstring example for external components
+        "esphome/components/esp8266/const.py",
     ],
 )
 def lint_relative_py_import(fname: Path, line, col, content):
diff --git a/tests/component_tests/binary_sensor/test_binary_sensor.py b/tests/component_tests/binary_sensor/test_binary_sensor.py
index 86e07050231..ce4e64681fe 100644
--- a/tests/component_tests/binary_sensor/test_binary_sensor.py
+++ b/tests/component_tests/binary_sensor/test_binary_sensor.py
@@ -29,7 +29,7 @@ def test_binary_sensor_sets_mandatory_fields(generate_main):
     )
 
     # Then
-    assert 'bs_1->set_name_and_object_id("test bs1", "test_bs1");' in main_cpp
+    assert 'bs_1->set_name("test bs1",' in main_cpp
     assert "bs_1->set_pin(" in main_cpp
 
 
diff --git a/tests/component_tests/button/test_button.py b/tests/component_tests/button/test_button.py
index b21665288c2..797b6fb1a42 100644
--- a/tests/component_tests/button/test_button.py
+++ b/tests/component_tests/button/test_button.py
@@ -26,7 +26,7 @@ def test_button_sets_mandatory_fields(generate_main):
     main_cpp = generate_main("tests/component_tests/button/test_button.yaml")
 
     # Then
-    assert 'wol_1->set_name_and_object_id("wol_test_1", "wol_test_1");' in main_cpp
+    assert 'wol_1->set_name("wol_test_1",' in main_cpp
     assert "wol_2->set_macaddr(18, 52, 86, 120, 144, 171);" in main_cpp
 
 
diff --git a/tests/component_tests/text/test_text.py b/tests/component_tests/text/test_text.py
index bfc3131f6d3..6b047bc62fb 100644
--- a/tests/component_tests/text/test_text.py
+++ b/tests/component_tests/text/test_text.py
@@ -25,7 +25,7 @@ def test_text_sets_mandatory_fields(generate_main):
     main_cpp = generate_main("tests/component_tests/text/test_text.yaml")
 
     # Then
-    assert 'it_1->set_name_and_object_id("test 1 text", "test_1_text");' in main_cpp
+    assert 'it_1->set_name("test 1 text",' in main_cpp
 
 
 def test_text_config_value_internal_set(generate_main):
diff --git a/tests/component_tests/text_sensor/test_text_sensor.py b/tests/component_tests/text_sensor/test_text_sensor.py
index 934ee67cef0..1593d0b6d8e 100644
--- a/tests/component_tests/text_sensor/test_text_sensor.py
+++ b/tests/component_tests/text_sensor/test_text_sensor.py
@@ -25,18 +25,9 @@ def test_text_sensor_sets_mandatory_fields(generate_main):
     main_cpp = generate_main("tests/component_tests/text_sensor/test_text_sensor.yaml")
 
     # Then
-    assert (
-        'ts_1->set_name_and_object_id("Template Text Sensor 1", "template_text_sensor_1");'
-        in main_cpp
-    )
-    assert (
-        'ts_2->set_name_and_object_id("Template Text Sensor 2", "template_text_sensor_2");'
-        in main_cpp
-    )
-    assert (
-        'ts_3->set_name_and_object_id("Template Text Sensor 3", "template_text_sensor_3");'
-        in main_cpp
-    )
+    assert 'ts_1->set_name("Template Text Sensor 1",' in main_cpp
+    assert 'ts_2->set_name("Template Text Sensor 2",' in main_cpp
+    assert 'ts_3->set_name("Template Text Sensor 3",' in main_cpp
 
 
 def test_text_sensor_config_value_internal_set(generate_main):
diff --git a/tests/components/micronova/common.yaml b/tests/components/micronova/common.yaml
index 660970350a0..5870d3726fb 100644
--- a/tests/components/micronova/common.yaml
+++ b/tests/components/micronova/common.yaml
@@ -41,7 +41,7 @@ sensor:
 switch:
   - platform: micronova
     stove:
-      name: Stove on/off
+      name: Stove
 
 text_sensor:
   - platform: micronova
diff --git a/tests/components/opentherm/common.yaml b/tests/components/opentherm/common.yaml
index 1e58a04bf0f..fb5fb39eb84 100644
--- a/tests/components/opentherm/common.yaml
+++ b/tests/components/opentherm/common.yaml
@@ -92,7 +92,7 @@ sensor:
     ch_pump_starts:
       name: "Boiler Number of starts CH pump"
     dhw_pump_valve_starts:
-      name: "Boiler Number of starts DHW pump/valve"
+      name: "Boiler Number of starts DHW pump valve"
     dhw_burner_starts:
       name: "Boiler Number of starts burner during DHW mode"
     burner_operation_hours:
@@ -139,7 +139,7 @@ binary_sensor:
     dhw_present:
       name: "Boiler DHW present"
     control_type_on_off:
-      name: "Boiler Control type is on/off"
+      name: "Boiler Control type is on-off"
     cooling_supported:
       name: "Boiler Cooling supported"
     dhw_storage_tank:
@@ -153,9 +153,9 @@ binary_sensor:
     max_ch_setpoint_transfer_enabled:
       name: "Boiler CH maximum setpoint transfer enabled"
     dhw_setpoint_rw:
-      name: "Boiler DHW setpoint read/write"
+      name: "Boiler DHW setpoint read-write"
     max_ch_setpoint_rw:
-      name: "Boiler CH maximum setpoint read/write"
+      name: "Boiler CH maximum setpoint read-write"
 
 switch:
   - platform: opentherm
diff --git a/tests/components/zhlt01/common.yaml b/tests/components/zhlt01/common.yaml
index d0fd531c877..483f9f3c4e5 100644
--- a/tests/components/zhlt01/common.yaml
+++ b/tests/components/zhlt01/common.yaml
@@ -1,4 +1,4 @@
 climate:
   - platform: zhlt01
-    name: ZH/LT-01 Climate
+    name: ZH-LT-01 Climate
     transmitter_id: xmitr
diff --git a/tests/integration/conftest.py b/tests/integration/conftest.py
index 965363972f0..50e8d4122bf 100644
--- a/tests/integration/conftest.py
+++ b/tests/integration/conftest.py
@@ -51,6 +51,9 @@ if platform.system() == "Windows":
 
 import pty  # not available on Windows
 
+# Register assert rewrite for entity_utils so assertions have proper error messages
+pytest.register_assert_rewrite("tests.integration.entity_utils")
+
 
 def _get_platformio_env(cache_dir: Path) -> dict[str, str]:
     """Get environment variables for PlatformIO with shared cache."""
diff --git a/tests/integration/entity_utils.py b/tests/integration/entity_utils.py
new file mode 100644
index 00000000000..7596983ee23
--- /dev/null
+++ b/tests/integration/entity_utils.py
@@ -0,0 +1,145 @@
+"""Utilities for computing entity object_id in integration tests.
+
+This module contains the algorithm that aioesphomeapi will use to compute
+object_id client-side from API data.
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from esphome.helpers import fnv1_hash_object_id, sanitize, snake_case
+
+if TYPE_CHECKING:
+    from aioesphomeapi import DeviceInfo, EntityInfo
+
+
+def compute_object_id(name: str) -> str:
+    """Compute object_id from name using snake_case + sanitize."""
+    return sanitize(snake_case(name))
+
+
+def infer_name_add_mac_suffix(device_info: DeviceInfo) -> bool:
+    """Infer name_add_mac_suffix from device name ending with MAC suffix."""
+    mac_suffix = device_info.mac_address.replace(":", "")[-6:].lower()
+    return device_info.name.endswith(f"-{mac_suffix}")
+
+
+def _get_name_for_object_id(
+    entity: EntityInfo,
+    device_info: DeviceInfo,
+    device_id_to_name: dict[int, str],
+) -> str:
+    """Get the name used for object_id computation.
+
+    This is the algorithm that aioesphomeapi will use to determine which
+    name to use for computing object_id client-side from API data.
+
+    Args:
+        entity: The entity to get name for
+        device_info: Device info from the API
+        device_id_to_name: Mapping of device_id to device name for sub-devices
+
+    Returns:
+        The name to use for object_id computation
+    """
+    if entity.name:
+        # Named entity: use entity name
+        return entity.name
+    if entity.device_id != 0:
+        # Empty name on sub-device: use sub-device name
+        return device_id_to_name[entity.device_id]
+    if infer_name_add_mac_suffix(device_info) or device_info.friendly_name:
+        # Empty name on main device with MAC suffix or friendly_name: use friendly_name
+        # (even if empty - this is bug-for-bug compatibility for MAC suffix case)
+        return device_info.friendly_name
+    # Empty name on main device, no friendly_name: use device name
+    return device_info.name
+
+
+def compute_entity_object_id(
+    entity: EntityInfo,
+    device_info: DeviceInfo,
+    device_id_to_name: dict[int, str],
+) -> str:
+    """Compute expected object_id for an entity.
+
+    Args:
+        entity: The entity to compute object_id for
+        device_info: Device info from the API
+        device_id_to_name: Mapping of device_id to device name for sub-devices
+
+    Returns:
+        The computed object_id string
+    """
+    name_for_id = _get_name_for_object_id(entity, device_info, device_id_to_name)
+    return compute_object_id(name_for_id)
+
+
+def compute_entity_hash(
+    entity: EntityInfo,
+    device_info: DeviceInfo,
+    device_id_to_name: dict[int, str],
+) -> int:
+    """Compute expected object_id hash for an entity.
+
+    Args:
+        entity: The entity to compute hash for
+        device_info: Device info from the API
+        device_id_to_name: Mapping of device_id to device name for sub-devices
+
+    Returns:
+        The computed FNV-1 hash
+    """
+    name_for_id = _get_name_for_object_id(entity, device_info, device_id_to_name)
+    return fnv1_hash_object_id(name_for_id)
+
+
+def verify_entity_object_id(
+    entity: EntityInfo,
+    device_info: DeviceInfo,
+    device_id_to_name: dict[int, str],
+) -> None:
+    """Verify an entity's object_id and hash match the expected values.
+
+    Args:
+        entity: The entity to verify
+        device_info: Device info from the API
+        device_id_to_name: Mapping of device_id to device name for sub-devices
+
+    Raises:
+        AssertionError: If object_id or hash doesn't match expected value
+    """
+    expected_object_id = compute_entity_object_id(
+        entity, device_info, device_id_to_name
+    )
+    assert entity.object_id == expected_object_id, (
+        f"object_id mismatch for entity '{entity.name}': "
+        f"expected '{expected_object_id}', got '{entity.object_id}'"
+    )
+
+    expected_hash = compute_entity_hash(entity, device_info, device_id_to_name)
+    assert entity.key == expected_hash, (
+        f"hash mismatch for entity '{entity.name}': "
+        f"expected {expected_hash:#x}, got {entity.key:#x}"
+    )
+
+
+def verify_all_entities(
+    entities: list[EntityInfo],
+    device_info: DeviceInfo,
+) -> None:
+    """Verify all entities have correct object_id and hash values.
+
+    Args:
+        entities: List of entities to verify
+        device_info: Device info from the API
+
+    Raises:
+        AssertionError: If any entity's object_id or hash doesn't match
+    """
+    # Build device_id -> name lookup from sub-devices
+    device_id_to_name = {d.device_id: d.name for d in device_info.devices}
+
+    for entity in entities:
+        verify_entity_object_id(entity, device_info, device_id_to_name)
diff --git a/tests/integration/fixtures/fnv1_hash_object_id.yaml b/tests/integration/fixtures/fnv1_hash_object_id.yaml
new file mode 100644
index 00000000000..2097b2fbf9c
--- /dev/null
+++ b/tests/integration/fixtures/fnv1_hash_object_id.yaml
@@ -0,0 +1,76 @@
+esphome:
+  name: fnv1-hash-object-id-test
+  platformio_options:
+    build_flags:
+      - "-DDEBUG"
+  on_boot:
+    - lambda: |-
+        using esphome::fnv1_hash_object_id;
+
+        // Test basic lowercase (hash matches Python fnv1_hash_object_id("foo"))
+        uint32_t hash_foo = fnv1_hash_object_id("foo", 3);
+        if (hash_foo == 0x408f5e13) {
+          ESP_LOGI("FNV1_OID", "foo PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "foo FAILED: 0x%08x != 0x408f5e13", hash_foo);
+        }
+
+        // Test uppercase conversion (should match lowercase)
+        uint32_t hash_Foo = fnv1_hash_object_id("Foo", 3);
+        if (hash_Foo == 0x408f5e13) {
+          ESP_LOGI("FNV1_OID", "upper PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "upper FAILED: 0x%08x != 0x408f5e13", hash_Foo);
+        }
+
+        // Test space to underscore conversion ("foo bar" -> "foo_bar")
+        uint32_t hash_space = fnv1_hash_object_id("foo bar", 7);
+        if (hash_space == 0x3ae35aa1) {
+          ESP_LOGI("FNV1_OID", "space PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "space FAILED: 0x%08x != 0x3ae35aa1", hash_space);
+        }
+
+        // Test underscore preserved ("foo_bar")
+        uint32_t hash_underscore = fnv1_hash_object_id("foo_bar", 7);
+        if (hash_underscore == 0x3ae35aa1) {
+          ESP_LOGI("FNV1_OID", "underscore PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "underscore FAILED: 0x%08x != 0x3ae35aa1", hash_underscore);
+        }
+
+        // Test hyphen preserved ("foo-bar")
+        uint32_t hash_hyphen = fnv1_hash_object_id("foo-bar", 7);
+        if (hash_hyphen == 0x438b12e3) {
+          ESP_LOGI("FNV1_OID", "hyphen PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "hyphen FAILED: 0x%08x != 0x438b12e3", hash_hyphen);
+        }
+
+        // Test special chars become underscore ("foo!bar" -> "foo_bar")
+        uint32_t hash_special = fnv1_hash_object_id("foo!bar", 7);
+        if (hash_special == 0x3ae35aa1) {
+          ESP_LOGI("FNV1_OID", "special PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "special FAILED: 0x%08x != 0x3ae35aa1", hash_special);
+        }
+
+        // Test complex name ("My Sensor Name" -> "my_sensor_name")
+        uint32_t hash_complex = fnv1_hash_object_id("My Sensor Name", 14);
+        if (hash_complex == 0x2760962a) {
+          ESP_LOGI("FNV1_OID", "complex PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "complex FAILED: 0x%08x != 0x2760962a", hash_complex);
+        }
+
+        // Test empty string returns FNV1_OFFSET_BASIS
+        uint32_t hash_empty = fnv1_hash_object_id("", 0);
+        if (hash_empty == 0x811c9dc5) {
+          ESP_LOGI("FNV1_OID", "empty PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "empty FAILED: 0x%08x != 0x811c9dc5", hash_empty);
+        }
+
+host:
+api:
+logger:
diff --git a/tests/integration/fixtures/object_id_api_verification.yaml b/tests/integration/fixtures/object_id_api_verification.yaml
new file mode 100644
index 00000000000..386270fc2c1
--- /dev/null
+++ b/tests/integration/fixtures/object_id_api_verification.yaml
@@ -0,0 +1,125 @@
+esphome:
+  name: object-id-test
+  friendly_name: Test Device
+  # Enable MAC suffix - host MAC is 98:35:69:ab:f6:79, suffix is "abf679"
+  # friendly_name becomes "Test Device abf679"
+  name_add_mac_suffix: true
+  # Sub-devices for testing empty-name entities on devices
+  devices:
+    - id: sub_device_1
+      name: Sub Device One
+    - id: sub_device_2
+      name: Sub Device Two
+
+host:
+
+api:
+
+logger:
+
+sensor:
+  # Test 1: Basic name -> object_id = "temperature_sensor"
+  - platform: template
+    name: "Temperature Sensor"
+    id: sensor_basic
+    lambda: return 42.0;
+    update_interval: 60s
+
+  # Test 2: Uppercase name -> object_id = "uppercase_name"
+  - platform: template
+    name: "UPPERCASE NAME"
+    id: sensor_uppercase
+    lambda: return 43.0;
+    update_interval: 60s
+
+  # Test 3: Special characters -> object_id = "special__chars_"
+  - platform: template
+    name: "Special!@Chars#"
+    id: sensor_special
+    lambda: return 44.0;
+    update_interval: 60s
+
+  # Test 4: Hyphen preserved -> object_id = "temp-sensor"
+  - platform: template
+    name: "Temp-Sensor"
+    id: sensor_hyphen
+    lambda: return 45.0;
+    update_interval: 60s
+
+  # Test 5: Underscore preserved -> object_id = "temp_sensor"
+  - platform: template
+    name: "Temp_Sensor"
+    id: sensor_underscore
+    lambda: return 46.0;
+    update_interval: 60s
+
+  # Test 6: Mixed case with spaces -> object_id = "living_room_temperature"
+  - platform: template
+    name: "Living Room Temperature"
+    id: sensor_mixed
+    lambda: return 47.0;
+    update_interval: 60s
+
+  # Test 7: Empty name - uses friendly_name with MAC suffix
+  # friendly_name = "Test Device abf679" -> object_id = "test_device_abf679"
+  - platform: template
+    name: ""
+    id: sensor_empty_name
+    lambda: return 48.0;
+    update_interval: 60s
+
+binary_sensor:
+  # Test 8: Different platform same conversion rules
+  - platform: template
+    name: "Door Open"
+    id: binary_door
+    lambda: return true;
+
+  # Test 9: Numbers in name -> object_id = "sensor_123"
+  - platform: template
+    name: "Sensor 123"
+    id: binary_numbers
+    lambda: return false;
+
+switch:
+  # Test 10: Long name with multiple spaces
+  - platform: template
+    name: "My Very Long Switch Name Here"
+    id: switch_long
+    lambda: return false;
+    turn_on_action:
+      - logger.log: "on"
+    turn_off_action:
+      - logger.log: "off"
+
+text_sensor:
+  # Test 11: Name starting with number (should work fine)
+  - platform: template
+    name: "123 Start"
+    id: text_num_start
+    lambda: return {"test"};
+    update_interval: 60s
+
+button:
+  # Test 12: Named entity on sub-device -> object_id from entity name
+  - platform: template
+    name: "Device Button"
+    id: button_on_device
+    device_id: sub_device_1
+    on_press: []
+
+  # Test 13: Empty name on sub-device -> object_id from device name
+  # Device name "Sub Device One" -> object_id = "sub_device_one"
+  - platform: template
+    name: ""
+    id: button_empty_on_device1
+    device_id: sub_device_1
+    on_press: []
+
+  # Test 14: Empty name on different sub-device
+  # Device name "Sub Device Two" -> object_id = "sub_device_two"
+  - platform: template
+    name: ""
+    id: button_empty_on_device2
+    device_id: sub_device_2
+    on_press: []
diff --git a/tests/integration/fixtures/object_id_friendly_name_no_mac_suffix.yaml b/tests/integration/fixtures/object_id_friendly_name_no_mac_suffix.yaml
new file mode 100644
index 00000000000..7a86e37d083
--- /dev/null
+++ b/tests/integration/fixtures/object_id_friendly_name_no_mac_suffix.yaml
@@ -0,0 +1,27 @@
+esphome:
+  name: test-device
+  # friendly_name set but NO MAC suffix
+  # Empty-name entity should use friendly_name for object_id
+  friendly_name: My Friendly Device
+
+host:
+
+api:
+
+logger:
+
+sensor:
+  # Empty name entity - should use friendly_name for object_id
+  # friendly_name = "My Friendly Device" -> object_id = "my_friendly_device"
+  - platform: template
+    name: ""
+    id: sensor_empty_name
+    lambda: return 42.0;
+    update_interval: 60s
+
+  # Named entity for comparison
+  - platform: template
+    name: "Temperature"
+    id: sensor_named
+    lambda: return 43.0;
+    update_interval: 60s
diff --git a/tests/integration/fixtures/object_id_no_friendly_name_no_mac_suffix.yaml b/tests/integration/fixtures/object_id_no_friendly_name_no_mac_suffix.yaml
new file mode 100644
index 00000000000..4a947e0f6af
--- /dev/null
+++ b/tests/integration/fixtures/object_id_no_friendly_name_no_mac_suffix.yaml
@@ -0,0 +1,25 @@
+esphome:
+  name: test-device
+  # No friendly_name set, no MAC suffix
+  # OLD behavior: object_id = device name because Python pre-computed with fallback
+
+host:
+
+api:
+
+logger:
+
+sensor:
+  # Empty name entity - OLD behavior used device name as fallback
+  - platform: template
+    name: ""
+    id: sensor_empty_name
+    lambda: return 42.0;
+    update_interval: 60s
+
+  # Named entity for comparison
+  - platform: template
+    name: "Temperature"
+    id: sensor_named
+    lambda: return 43.0;
+    update_interval: 60s
diff --git a/tests/integration/fixtures/object_id_no_friendly_name_with_mac_suffix.yaml b/tests/integration/fixtures/object_id_no_friendly_name_with_mac_suffix.yaml
new file mode 100644
index 00000000000..ab12e670a03
--- /dev/null
+++ b/tests/integration/fixtures/object_id_no_friendly_name_with_mac_suffix.yaml
@@ -0,0 +1,26 @@
+esphome:
+  name: test-device
+  # No friendly_name set, MAC suffix enabled
+  # OLD behavior: object_id = "" (empty) because is_object_id_dynamic_() used App.get_friendly_name() directly
+  name_add_mac_suffix: true
+
+host:
+
+api:
+
+logger:
+
+sensor:
+  # Empty name entity - OLD behavior produced empty object_id when MAC suffix enabled
+  - platform: template
+    name: ""
+    id: sensor_empty_name
+    lambda: return 42.0;
+    update_interval: 60s
+
+  # Named entity for comparison
+  - platform: template
+    name: "Temperature"
+    id: sensor_named
+    lambda: return 43.0;
+    update_interval: 60s
diff --git a/tests/integration/test_fnv1_hash_object_id.py b/tests/integration/test_fnv1_hash_object_id.py
new file mode 100644
index 00000000000..23e8ca04c23
--- /dev/null
+++ b/tests/integration/test_fnv1_hash_object_id.py
@@ -0,0 +1,75 @@
+"""Integration test for fnv1_hash_object_id function.
+
+This test verifies that the C++ fnv1_hash_object_id() function in
+esphome/core/helpers.h produces the same hash values as the Python
+fnv1_hash_object_id() function in esphome/helpers.py.
+
+If this test fails, one of the implementations has diverged and needs
+to be updated to match the other.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import re
+
+import pytest
+
+from .types import APIClientConnectedFactory, RunCompiledFunction
+
+
+@pytest.mark.asyncio
+async def test_fnv1_hash_object_id(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test that C++ fnv1_hash_object_id matches Python implementation."""
+
+    test_results: dict[str, str] = {}
+    all_tests_complete = asyncio.Event()
+    expected_tests = {
+        "foo",
+        "upper",
+        "space",
+        "underscore",
+        "hyphen",
+        "special",
+        "complex",
+        "empty",
+    }
+
+    def on_log_line(line: str) -> None:
+        """Capture log lines with test results."""
+        # Strip ANSI escape codes
+        clean_line = re.sub(r"\x1b\[[0-9;]*m", "", line)
+        # Look for our test result messages
+        # Format: "[timestamp][level][FNV1_OID:line]: test_name PASSED"
+        match = re.search(r"\[FNV1_OID:\d+\]:\s+(\w+)\s+(PASSED|FAILED)", clean_line)
+        if match:
+            test_name = match.group(1)
+            result = match.group(2)
+            test_results[test_name] = result
+            if set(test_results.keys()) >= expected_tests:
+                all_tests_complete.set()
+
+    async with (
+        run_compiled(yaml_config, line_callback=on_log_line),
+        api_client_connected() as client,
+    ):
+        device_info = await client.device_info()
+        assert device_info is not None
+        assert device_info.name == "fnv1-hash-object-id-test"
+
+        # Wait for all tests to complete or timeout
+        try:
+            await asyncio.wait_for(all_tests_complete.wait(), timeout=2.0)
+        except TimeoutError:
+            pytest.fail(f"Tests timed out. Got results for: {set(test_results.keys())}")
+
+        # Verify all tests passed
+        for test_name in expected_tests:
+            assert test_name in test_results, f"{test_name} test not found"
+            assert test_results[test_name] == "PASSED", (
+                f"{test_name} test failed - C++ and Python hash mismatch"
+            )
diff --git a/tests/integration/test_object_id_api_verification.py b/tests/integration/test_object_id_api_verification.py
new file mode 100644
index 00000000000..c8603e06829
--- /dev/null
+++ b/tests/integration/test_object_id_api_verification.py
@@ -0,0 +1,176 @@
+"""Integration test to verify object_id from API matches Python computation.
+
+This test verifies a three-way match between:
+1. C++ object_id generation (get_object_id_to using to_sanitized_char/to_snake_case_char)
+2. C++ hash generation (fnv1_hash_object_id in helpers.h)
+3. Python computation (sanitize/snake_case in helpers.py, fnv1_hash_object_id)
+
+The API response contains C++ computed values, so verifying API == Python
+implicitly verifies C++ == Python == API for both object_id and hash.
+
+This is important for the planned migration to remove object_id from the API
+protocol and have clients (like aioesphomeapi) compute it from the name.
+See: https://github.com/esphome/backlog/issues/76
+
+Test cases covered:
+- Named entities with various characters (uppercase, special chars, hyphens, etc.)
+- Empty-name entities on main device (uses device's friendly_name with MAC suffix)
+- Empty-name entities on sub-devices (uses sub-device's name)
+- Named entities on sub-devices (uses entity name, not device name)
+- MAC suffix handling (name_add_mac_suffix modifies friendly_name at runtime)
+- Both object_id string and hash (key) verification
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from esphome.helpers import fnv1_hash_object_id
+
+from .entity_utils import compute_object_id, verify_all_entities
+from .types import APIClientConnectedFactory, RunCompiledFunction
+
+# Host platform default MAC: 98:35:69:ab:f6:79 -> suffix "abf679"
+MAC_SUFFIX = "abf679"
+
+
+# Expected entities with their own names and expected object_ids
+# Format: (entity_name, expected_object_id)
+NAMED_ENTITIES = [
+    # sensor platform
+    ("Temperature Sensor", "temperature_sensor"),
+    ("UPPERCASE NAME", "uppercase_name"),
+    ("Special!@Chars#", "special__chars_"),
+    ("Temp-Sensor", "temp-sensor"),
+    ("Temp_Sensor", "temp_sensor"),
+    ("Living Room Temperature", "living_room_temperature"),
+    # binary_sensor platform
+    ("Door Open", "door_open"),
+    ("Sensor 123", "sensor_123"),
+    # switch platform
+    ("My Very Long Switch Name Here", "my_very_long_switch_name_here"),
+    # text_sensor platform
+    ("123 Start", "123_start"),
+    # button platform - named entity on sub-device (uses entity name, not device name)
+    ("Device Button", "device_button"),
+]
+
+# Sub-device names and their expected object_ids for empty-name entities
+# Format: (device_name, expected_object_id)
+SUB_DEVICE_EMPTY_NAME_ENTITIES = [
+    ("Sub Device One", "sub_device_one"),
+    ("Sub Device Two", "sub_device_two"),
+]
+
+
+@pytest.mark.asyncio
+async def test_object_id_api_verification(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test that object_id from API matches Python computation.
+
+    Tests:
+    1. Named entities - object_id computed from entity name
+    2. Empty-name entities - object_id computed from friendly_name (with MAC suffix)
+    3. Hash verification - key can be computed from name
+    4. Generic verification - all entities can have object_id computed from API data
+    """
+    async with run_compiled(yaml_config), api_client_connected() as client:
+        # Get device info
+        device_info = await client.device_info()
+        assert device_info is not None
+
+        # Device name should include MAC suffix (hyphen separator)
+        assert device_info.name == f"object-id-test-{MAC_SUFFIX}", (
+            f"Device name mismatch: got '{device_info.name}'"
+        )
+        # Friendly name should include MAC suffix (space separator)
+        expected_friendly_name = f"Test Device {MAC_SUFFIX}"
+        assert device_info.friendly_name == expected_friendly_name, (
+            f"Friendly name mismatch: got '{device_info.friendly_name}'"
+        )
+
+        # Get all entities
+        entities, _ = await client.list_entities_services()
+
+        # Create a map of entity names to entity info
+        entity_map = {}
+        for entity in entities:
+            entity_map[entity.name] = entity
+
+        # === Test 1: Verify each named entity ===
+        for entity_name, expected_object_id in NAMED_ENTITIES:
+            assert entity_name in entity_map, (
+                f"Entity '{entity_name}' not found in API response. "
+                f"Available: {list(entity_map.keys())}"
+            )
+
+            entity = entity_map[entity_name]
+
+            # Verify object_id matches expected
+            assert entity.object_id == expected_object_id, (
+                f"Entity '{entity_name}': object_id mismatch. "
+                f"API returned '{entity.object_id}', expected '{expected_object_id}'"
+            )
+
+            # Verify Python computation matches
+            computed = compute_object_id(entity_name)
+            assert computed == expected_object_id, (
+                f"Entity '{entity_name}': Python computation mismatch. "
+                f"Computed '{computed}', expected '{expected_object_id}'"
+            )
+
+            # Verify hash can be computed from the name
+            hash_from_name = fnv1_hash_object_id(entity_name)
+            assert hash_from_name == entity.key, (
+                f"Entity '{entity_name}': hash mismatch. "
+                f"Python hash {hash_from_name:#x}, API key {entity.key:#x}"
+            )
+
+        # === Test 2: Verify empty-name entities ===
+        # Empty-name entities have name="" in API, object_id comes from:
+        # - Main device: friendly_name (with MAC suffix)
+        # - Sub-device: device name
+
+        # Get all empty-name entities
+        empty_name_entities = [e for e in entities if e.name == ""]
+        # We expect 3: 1 on main device, 2 on sub-devices
+        assert len(empty_name_entities) == 3, (
+            f"Expected 3 empty-name entities, got {len(empty_name_entities)}"
+        )
+
+        # Build device_id -> device_name map from device_info
+        device_id_to_name = {d.device_id: d.name for d in device_info.devices}
+
+        # Verify each empty-name entity
+        for entity in empty_name_entities:
+            if entity.device_id == 0:
+                # Main device - uses friendly_name with MAC suffix
+                expected_name = expected_friendly_name
+            else:
+                # Sub-device - uses device name
+                assert entity.device_id in device_id_to_name, (
+                    f"Entity device_id {entity.device_id} not found in devices"
+                )
+                expected_name = device_id_to_name[entity.device_id]
+
+            expected_object_id = compute_object_id(expected_name)
+            assert entity.object_id == expected_object_id, (
+                f"Empty-name entity (device_id={entity.device_id}): object_id mismatch. "
+                f"API: '{entity.object_id}', expected: '{expected_object_id}' "
+                f"(from name '{expected_name}')"
+            )
+
+            # Verify hash matches
+            expected_hash = fnv1_hash_object_id(expected_name)
+            assert entity.key == expected_hash, (
+                f"Empty-name entity (device_id={entity.device_id}): hash mismatch. "
+                f"API key: {entity.key:#x}, expected: {expected_hash:#x}"
+            )
+
+        # === Test 3: Verify ALL entities using the algorithm from entity_utils ===
+        # This uses the algorithm that aioesphomeapi will use to compute object_id
+        # client-side from API data.
+        verify_all_entities(entities, device_info)
diff --git a/tests/integration/test_object_id_friendly_name_no_mac_suffix.py b/tests/integration/test_object_id_friendly_name_no_mac_suffix.py
new file mode 100644
index 00000000000..7199a2b3719
--- /dev/null
+++ b/tests/integration/test_object_id_friendly_name_no_mac_suffix.py
@@ -0,0 +1,81 @@
+"""Integration test for object_id with friendly_name but no MAC suffix.
+
+This test covers Branch 4 of the algorithm:
+- Empty name on main device
+- NO MAC suffix enabled
+- friendly_name IS set
+- Result: use friendly_name for object_id
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from esphome.helpers import fnv1_hash_object_id
+
+from .entity_utils import (
+    compute_object_id,
+    infer_name_add_mac_suffix,
+    verify_all_entities,
+)
+from .types import APIClientConnectedFactory, RunCompiledFunction
+
+
+@pytest.mark.asyncio
+async def test_object_id_friendly_name_no_mac_suffix(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test object_id when friendly_name is set but no MAC suffix.
+
+    This covers Branch 4 of the algorithm:
+    - Empty name entity
+    - name_add_mac_suffix = false (or not set)
+    - friendly_name = "My Friendly Device"
+    - Expected: object_id = "my_friendly_device"
+    """
+    async with run_compiled(yaml_config), api_client_connected() as client:
+        device_info = await client.device_info()
+        assert device_info is not None
+
+        # Device name should NOT include MAC suffix
+        assert device_info.name == "test-device"
+
+        # Friendly name should be set
+        assert device_info.friendly_name == "My Friendly Device"
+
+        entities, _ = await client.list_entities_services()
+
+        # Find the empty-name entity
+        empty_name_entities = [e for e in entities if e.name == ""]
+        assert len(empty_name_entities) == 1
+
+        entity = empty_name_entities[0]
+
+        # Should use friendly_name for object_id (Branch 4)
+        expected_object_id = compute_object_id("My Friendly Device")
+        assert expected_object_id == "my_friendly_device"  # Verify our expectation
+        assert entity.object_id == expected_object_id, (
+            f"Expected object_id '{expected_object_id}' from friendly_name, "
+            f"got '{entity.object_id}'"
+        )
+
+        # Hash should match friendly_name
+        expected_hash = fnv1_hash_object_id("My Friendly Device")
+        assert entity.key == expected_hash, (
+            f"Expected hash {expected_hash:#x}, got {entity.key:#x}"
+        )
+
+        # Named entity should work normally
+        named_entities = [e for e in entities if e.name == "Temperature"]
+        assert len(named_entities) == 1
+        assert named_entities[0].object_id == "temperature"
+
+        # Verify our inference: no MAC suffix in this test
+        assert not infer_name_add_mac_suffix(device_info), (
+            "Device name should NOT have MAC suffix"
+        )
+
+        # Verify the full algorithm from entity_utils works for ALL entities
+        verify_all_entities(entities, device_info)
diff --git a/tests/integration/test_object_id_no_friendly_name.py b/tests/integration/test_object_id_no_friendly_name.py
new file mode 100644
index 00000000000..b548f02fde2
--- /dev/null
+++ b/tests/integration/test_object_id_no_friendly_name.py
@@ -0,0 +1,140 @@
+"""Integration tests for object_id when friendly_name is not set.
+
+These tests verify bug-for-bug compatibility with the old behavior:
+
+1. With MAC suffix enabled + no friendly_name:
+   - OLD: is_object_id_dynamic_() was true, used App.get_friendly_name() directly
+   - OLD: object_id = "" (empty) because friendly_name was empty
+   - NEW: Must maintain same behavior for compatibility
+
+2. Without MAC suffix + no friendly_name:
+   - OLD: is_object_id_dynamic_() was false, used pre-computed object_id_c_str_
+   - OLD: Python computed object_id with fallback to device name
+   - NEW: Must maintain same behavior (object_id = device name)
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from esphome.helpers import fnv1_hash_object_id
+
+from .entity_utils import compute_object_id, verify_all_entities
+from .types import APIClientConnectedFactory, RunCompiledFunction
+
+# Host platform default MAC: 98:35:69:ab:f6:79 -> suffix "abf679"
+MAC_SUFFIX = "abf679"
+
+# FNV1 offset basis - hash of empty string
+FNV1_OFFSET_BASIS = 2166136261
+
+
+@pytest.mark.asyncio
+async def test_object_id_no_friendly_name_with_mac_suffix(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test object_id when friendly_name not set but MAC suffix enabled.
+
+    OLD behavior (bug-for-bug compatibility):
+    - is_object_id_dynamic_() returned true (no own name AND mac suffix enabled)
+    - format_dynamic_object_id() used App.get_friendly_name() directly
+    - Since friendly_name was empty, object_id was empty
+
+    This was arguably a bug, but we maintain it for compatibility.
+    """
+    async with run_compiled(yaml_config), api_client_connected() as client:
+        device_info = await client.device_info()
+        assert device_info is not None
+
+        # Device name should include MAC suffix
+        expected_device_name = f"test-device-{MAC_SUFFIX}"
+        assert device_info.name == expected_device_name
+
+        # Friendly name should be empty (not set in config)
+        assert device_info.friendly_name == ""
+
+        entities, _ = await client.list_entities_services()
+
+        # Find the empty-name entity
+        empty_name_entities = [e for e in entities if e.name == ""]
+        assert len(empty_name_entities) == 1
+
+        entity = empty_name_entities[0]
+
+        # OLD behavior: object_id was empty because App.get_friendly_name() was empty
+        # This is bug-for-bug compatibility
+        assert entity.object_id == "", (
+            f"Expected empty object_id for bug-for-bug compatibility, "
+            f"got '{entity.object_id}'"
+        )
+
+        # Hash should be FNV1_OFFSET_BASIS (hash of empty string)
+        assert entity.key == FNV1_OFFSET_BASIS, (
+            f"Expected hash of empty string ({FNV1_OFFSET_BASIS:#x}), "
+            f"got {entity.key:#x}"
+        )
+
+        # Named entity should work normally
+        named_entities = [e for e in entities if e.name == "Temperature"]
+        assert len(named_entities) == 1
+        assert named_entities[0].object_id == "temperature"
+
+        # Verify the full algorithm from entity_utils works for ALL entities
+        verify_all_entities(entities, device_info)
+
+
+@pytest.mark.asyncio
+async def test_object_id_no_friendly_name_no_mac_suffix(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test object_id when friendly_name not set and no MAC suffix.
+
+    OLD behavior:
+    - is_object_id_dynamic_() returned false (mac suffix not enabled)
+    - Used object_id_c_str_ which was pre-computed in Python
+    - Python used get_base_entity_object_id() with fallback to CORE.name
+
+    Result: object_id = sanitize(snake_case(device_name))
+    """
+    async with run_compiled(yaml_config), api_client_connected() as client:
+        device_info = await client.device_info()
+        assert device_info is not None
+
+        # Device name should NOT include MAC suffix
+        assert device_info.name == "test-device"
+
+        # Friendly name should be empty (not set in config)
+        assert device_info.friendly_name == ""
+
+        entities, _ = await client.list_entities_services()
+
+        # Find the empty-name entity
+        empty_name_entities = [e for e in entities if e.name == ""]
+        assert len(empty_name_entities) == 1
+
+        entity = empty_name_entities[0]
+
+        # OLD behavior: object_id was computed from device name
+        expected_object_id = compute_object_id("test-device")
+        assert entity.object_id == expected_object_id, (
+            f"Expected object_id '{expected_object_id}' from device name, "
+            f"got '{entity.object_id}'"
+        )
+
+        # Hash should match device name
+        expected_hash = fnv1_hash_object_id("test-device")
+        assert entity.key == expected_hash, (
+            f"Expected hash {expected_hash:#x}, got {entity.key:#x}"
+        )
+
+        # Named entity should work normally
+        named_entities = [e for e in entities if e.name == "Temperature"]
+        assert len(named_entities) == 1
+        assert named_entities[0].object_id == "temperature"
+
+        # Verify the full algorithm from entity_utils works for ALL entities
+        verify_all_entities(entities, device_info)
diff --git a/tests/unit_tests/core/test_entity_helpers.py b/tests/unit_tests/core/test_entity_helpers.py
index 01de0f27f9c..a58d4784cee 100644
--- a/tests/unit_tests/core/test_entity_helpers.py
+++ b/tests/unit_tests/core/test_entity_helpers.py
@@ -27,13 +27,9 @@ from esphome.helpers import sanitize, snake_case
 
 from .common import load_config_from_fixture
 
-# Pre-compiled regex patterns for extracting object IDs from expressions
-# Matches both old format: .set_object_id("obj_id")
-# and new format: .set_name_and_object_id("name", "obj_id")
-OBJECT_ID_PATTERN = re.compile(r'\.set_object_id\(["\'](.*?)["\']\)')
-COMBINED_PATTERN = re.compile(
-    r'\.set_name_and_object_id\(["\'].*?["\']\s*,\s*["\'](.*?)["\']\)'
-)
+# Pre-compiled regex pattern for extracting names from set_name calls
+# Matches: .set_name("name", hash) or .set_name("name")
+SET_NAME_PATTERN = re.compile(r'\.set_name\(["\']([^"\']*)["\']')
 
 FIXTURES_DIR = Path(__file__).parent.parent / "fixtures" / "core" / "entity_helpers"
 
@@ -276,14 +272,21 @@ def setup_test_environment() -> Generator[list[str], None, None]:
 
 
 def extract_object_id_from_expressions(expressions: list[str]) -> str | None:
-    """Extract the object ID that was set from the generated expressions."""
+    """Extract the object ID that would be computed from set_name calls.
+
+    Since object_id is now computed from the name (via snake_case + sanitize),
+    we extract the name from set_name() calls and compute the expected object_id.
+    For empty names, we fall back to CORE.friendly_name or CORE.name.
+    """
     for expr in expressions:
-        # First try new combined format: .set_name_and_object_id("name", "obj_id")
-        if match := COMBINED_PATTERN.search(expr):
-            return match.group(1)
-        # Fall back to old format: .set_object_id("obj_id")
-        if match := OBJECT_ID_PATTERN.search(expr):
-            return match.group(1)
+        if match := SET_NAME_PATTERN.search(expr):
+            name = match.group(1)
+            if name:
+                return sanitize(snake_case(name))
+            # Empty name - fall back to friendly_name or device name
+            if CORE.friendly_name:
+                return sanitize(snake_case(CORE.friendly_name))
+            return sanitize(snake_case(CORE.name)) if CORE.name else None
     return None
 
 
@@ -757,3 +760,140 @@ def test_entity_duplicate_validator_same_name_no_enhanced_message() -> None:
         r"Each entity on a device must have a unique name within its platform\.$",
     ):
         validator(config2)
+
+
+@pytest.mark.asyncio
+async def test_setup_entity_empty_name_with_device(
+    setup_test_environment: list[str],
+) -> None:
+    """Test setup_entity with empty entity name on a sub-device.
+
+    For empty-name entities, Python passes 0 and C++ calculates the hash
+    at runtime from the device's actual name.
+    """
+    added_expressions = setup_test_environment
+
+    # Mock get_variable to return a mock device
+    original_get_variable = entity_helpers.get_variable
+
+    async def mock_get_variable(id_: ID) -> MockObj:
+        return MockObj("sub_device_1")
+
+    entity_helpers.get_variable = mock_get_variable
+
+    var = MockObj("sensor1")
+    device_id = ID("sub_device_1", type="Device")
+
+    config = {
+        CONF_NAME: "",
+        CONF_DISABLED_BY_DEFAULT: False,
+        CONF_DEVICE_ID: device_id,
+    }
+
+    await setup_entity(var, config, "sensor")
+
+    entity_helpers.get_variable = original_get_variable
+
+    # Check that set_device was called
+    assert any("sensor1.set_device" in expr for expr in added_expressions)
+
+    # For empty-name entities, Python passes 0 - C++ calculates hash at runtime
+    assert any('set_name("", 0)' in expr for expr in added_expressions), (
+        f"Expected set_name with hash 0, got {added_expressions}"
+    )
+
+
+@pytest.mark.asyncio
+async def test_setup_entity_empty_name_with_mac_suffix(
+    setup_test_environment: list[str],
+) -> None:
+    """Test setup_entity with empty name and MAC suffix enabled.
+
+    For empty-name entities, Python passes 0 and C++ calculates the hash
+    at runtime from friendly_name (bug-for-bug compatibility).
+    """
+    added_expressions = setup_test_environment
+
+    # Set up CORE.config with name_add_mac_suffix enabled
+    CORE.config = {"name_add_mac_suffix": True}
+    # Set friendly_name to a specific value
+    CORE.friendly_name = "My Device"
+
+    var = MockObj("sensor1")
+
+    config = {
+        CONF_NAME: "",
+        CONF_DISABLED_BY_DEFAULT: False,
+    }
+
+    await setup_entity(var, config, "sensor")
+
+    # For empty-name entities, Python passes 0 - C++ calculates hash at runtime
+    assert any('set_name("", 0)' in expr for expr in added_expressions), (
+        f"Expected set_name with hash 0, got {added_expressions}"
+    )
+
+
+@pytest.mark.asyncio
+async def test_setup_entity_empty_name_with_mac_suffix_no_friendly_name(
+    setup_test_environment: list[str],
+) -> None:
+    """Test setup_entity with empty name, MAC suffix enabled, but no friendly_name.
+
+    For empty-name entities, Python passes 0 and C++ calculates the hash
+    at runtime. In this case C++ will hash the empty friendly_name
+    (bug-for-bug compatibility).
+    """
+    added_expressions = setup_test_environment
+
+    # Set up CORE.config with name_add_mac_suffix enabled
+    CORE.config = {"name_add_mac_suffix": True}
+    # Set friendly_name to empty
+    CORE.friendly_name = ""
+
+    var = MockObj("sensor1")
+
+    config = {
+        CONF_NAME: "",
+        CONF_DISABLED_BY_DEFAULT: False,
+    }
+
+    await setup_entity(var, config, "sensor")
+
+    # For empty-name entities, Python passes 0 - C++ calculates hash at runtime
+    assert any('set_name("", 0)' in expr for expr in added_expressions), (
+        f"Expected set_name with hash 0, got {added_expressions}"
+    )
+
+
+@pytest.mark.asyncio
+async def test_setup_entity_empty_name_no_mac_suffix_no_friendly_name(
+    setup_test_environment: list[str],
+) -> None:
+    """Test setup_entity with empty name, no MAC suffix, and no friendly_name.
+
+    For empty-name entities, Python passes 0 and C++ calculates the hash
+    at runtime from the device name.
+    """
+    added_expressions = setup_test_environment
+
+    # No MAC suffix (either not set or False)
+    CORE.config = {}
+    # No friendly_name
+    CORE.friendly_name = ""
+    # Device name is set
+    CORE.name = "my-test-device"
+
+    var = MockObj("sensor1")
+
+    config = {
+        CONF_NAME: "",
+        CONF_DISABLED_BY_DEFAULT: False,
+    }
+
+    await setup_entity(var, config, "sensor")
+
+    # For empty-name entities, Python passes 0 - C++ calculates hash at runtime
+    assert any('set_name("", 0)' in expr for expr in added_expressions), (
+        f"Expected set_name with hash 0, got {added_expressions}"
+    )
diff --git a/tests/unit_tests/test_helpers.py b/tests/unit_tests/test_helpers.py
index 47b945e0eb0..159d3230ab8 100644
--- a/tests/unit_tests/test_helpers.py
+++ b/tests/unit_tests/test_helpers.py
@@ -279,6 +279,77 @@ def test_sanitize(text, expected):
     assert actual == expected
 
 
+@pytest.mark.parametrize(
+    ("name", "expected_hash"),
+    (
+        # Basic strings - hash of sanitize(snake_case(name))
+        ("foo", 0x408F5E13),
+        ("Foo", 0x408F5E13),  # Same as "foo" (lowercase)
+        ("FOO", 0x408F5E13),  # Same as "foo" (lowercase)
+        # Spaces become underscores
+        ("foo bar", 0x3AE35AA1),  # Transforms to "foo_bar"
+        ("Foo Bar", 0x3AE35AA1),  # Same (lowercase + underscore)
+        # Already snake_case
+        ("foo_bar", 0x3AE35AA1),
+        # Special chars become underscores
+        ("foo!bar", 0x3AE35AA1),  # Transforms to "foo_bar"
+        ("foo@bar", 0x3AE35AA1),  # Transforms to "foo_bar"
+        # Hyphens are preserved
+        ("foo-bar", 0x438B12E3),
+        # Numbers are preserved
+        ("foo123", 0xF3B0067D),
+        # Empty string
+        ("", 0x811C9DC5),  # FNV1_OFFSET_BASIS (no chars processed)
+        # Single char
+        ("a", 0x050C5D7E),
+        # Mixed case and spaces
+        ("My Sensor Name", 0x2760962A),  # Transforms to "my_sensor_name"
+    ),
+)
+def test_fnv1_hash_object_id(name, expected_hash):
+    """Test fnv1_hash_object_id produces expected hashes.
+
+    These expected values were computed to match the C++ implementation
+    in esphome/core/helpers.h. If this test fails after modifying either
+    implementation, ensure both Python and C++ versions stay in sync.
+    """
+    actual = helpers.fnv1_hash_object_id(name)
+
+    assert actual == expected_hash
+
+
+def _fnv1_hash_py(s: str) -> int:
+    """Python implementation of FNV-1 hash for verification."""
+    hash_val = 2166136261  # FNV1_OFFSET_BASIS
+    for c in s:
+        hash_val = (hash_val * 16777619) & 0xFFFFFFFF  # FNV1_PRIME
+        hash_val ^= ord(c)
+    return hash_val
+
+
+@pytest.mark.parametrize(
+    "name",
+    (
+        "Simple",
+        "With Space",
+        "MixedCase",
+        "special!@#chars",
+        "already_snake_case",
+        "123numbers",
+    ),
+)
+def test_fnv1_hash_object_id_matches_manual_calculation(name):
+    """Verify fnv1_hash_object_id matches snake_case + sanitize + standard FNV-1."""
+    # Manual calculation: snake_case -> sanitize -> fnv1_hash
+    transformed = helpers.sanitize(helpers.snake_case(name))
+    expected = _fnv1_hash_py(transformed)
+
+    # Direct calculation via fnv1_hash_object_id
+    actual = helpers.fnv1_hash_object_id(name)
+
+    assert actual == expected
+
+
 @pytest.mark.parametrize(
     "text, expected",
     ((["127.0.0.1", "fe80::1", "2001::2"], ["2001::2", "127.0.0.1", "fe80::1"]),),