Merge branch 'dev' into get_peername_stack_save_ram

esphome/components/api/api.proto

@@ -477,7 +477,7 @@ message FanCommandRequest {
   bool has_speed_level = 10;
   int32 speed_level = 11;
   bool has_preset_mode = 12;
-  string preset_mode = 13;
+  string preset_mode = 13 [(pointer_to_buffer) = true];
   uint32 device_id = 14 [(field_ifdef) = "USE_DEVICES"];
 }
 
@@ -747,7 +747,7 @@ message NoiseEncryptionSetKeyRequest {
   option (source) = SOURCE_CLIENT;
   option (ifdef) = "USE_API_NOISE";
 
-  bytes key = 1;
+  bytes key = 1 [(pointer_to_buffer) = true];
 }
 
 message NoiseEncryptionSetKeyResponse {
@@ -824,9 +824,9 @@ message HomeAssistantStateResponse {
   option (no_delay) = true;
   option (ifdef) = "USE_API_HOMEASSISTANT_STATES";
 
-  string entity_id = 1;
-  string state = 2;
-  string attribute = 3;
+  string entity_id = 1 [(pointer_to_buffer) = true];
+  string state = 2 [(pointer_to_buffer) = true];
+  string attribute = 3 [(pointer_to_buffer) = true];
 }
 
 // ==================== IMPORT TIME ====================
@@ -1091,16 +1091,95 @@ message ClimateCommandRequest {
   bool has_swing_mode = 14;
   ClimateSwingMode swing_mode = 15;
   bool has_custom_fan_mode = 16;
-  string custom_fan_mode = 17;
+  string custom_fan_mode = 17 [(pointer_to_buffer) = true];
   bool has_preset = 18;
   ClimatePreset preset = 19;
   bool has_custom_preset = 20;
-  string custom_preset = 21;
+  string custom_preset = 21 [(pointer_to_buffer) = true];
   bool has_target_humidity = 22;
   float target_humidity = 23;
   uint32 device_id = 24 [(field_ifdef) = "USE_DEVICES"];
 }
 
+// ==================== WATER_HEATER ====================
+enum WaterHeaterMode {
+  WATER_HEATER_MODE_OFF = 0;
+  WATER_HEATER_MODE_ECO = 1;
+  WATER_HEATER_MODE_ELECTRIC = 2;
+  WATER_HEATER_MODE_PERFORMANCE = 3;
+  WATER_HEATER_MODE_HIGH_DEMAND = 4;
+  WATER_HEATER_MODE_HEAT_PUMP = 5;
+  WATER_HEATER_MODE_GAS = 6;
+}
+
+message ListEntitiesWaterHeaterResponse {
+  option (id) = 132;
+  option (base_class) = "InfoResponseProtoMessage";
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_WATER_HEATER";
+
+  string object_id = 1;
+  fixed32 key = 2;
+  string name = 3;
+  string icon = 4 [(field_ifdef) = "USE_ENTITY_ICON"];
+  bool disabled_by_default = 5;
+  EntityCategory entity_category = 6;
+  uint32 device_id = 7 [(field_ifdef) = "USE_DEVICES"];
+  float min_temperature = 8;
+  float max_temperature = 9;
+  float target_temperature_step = 10;
+  repeated WaterHeaterMode supported_modes = 11 [(container_pointer_no_template) = "water_heater::WaterHeaterModeMask"];
+  // Bitmask of WaterHeaterFeature flags
+  uint32 supported_features = 12;
+}
+
+message WaterHeaterStateResponse {
+  option (id) = 133;
+  option (base_class) = "StateResponseProtoMessage";
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_WATER_HEATER";
+  option (no_delay) = true;
+
+  fixed32 key = 1;
+  float current_temperature = 2;
+  float target_temperature = 3;
+  WaterHeaterMode mode = 4;
+  uint32 device_id = 5 [(field_ifdef) = "USE_DEVICES"];
+  // Bitmask of current state flags (bit 0 = away, bit 1 = on)
+  uint32 state = 6;
+  float target_temperature_low = 7;
+  float target_temperature_high = 8;
+}
+
+// Bitmask for WaterHeaterCommandRequest.has_fields
+enum WaterHeaterCommandHasField {
+  WATER_HEATER_COMMAND_HAS_NONE = 0;
+  WATER_HEATER_COMMAND_HAS_MODE = 1;
+  WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE = 2;
+  WATER_HEATER_COMMAND_HAS_STATE = 4;
+  WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_LOW = 8;
+  WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_HIGH = 16;
+}
+
+message WaterHeaterCommandRequest {
+  option (id) = 134;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_WATER_HEATER";
+  option (no_delay) = true;
+  option (base_class) = "CommandProtoMessage";
+
+  fixed32 key = 1;
+  // Bitmask of which fields are set (see WaterHeaterCommandHasField)
+  uint32 has_fields = 2;
+  WaterHeaterMode mode = 3;
+  float target_temperature = 4;
+  uint32 device_id = 5 [(field_ifdef) = "USE_DEVICES"];
+  // State flags bitmask (bit 0 = away, bit 1 = on)
+  uint32 state = 6;
+  float target_temperature_low = 7;
+  float target_temperature_high = 8;
+}
+
 // ==================== NUMBER ====================
 enum NumberMode {
   NUMBER_MODE_AUTO = 0;

esphome/components/api/api_connection.cpp

@@ -13,6 +13,7 @@
 #include <cinttypes>
 #include <functional>
 #include <limits>
+#include <new>
 #include <utility>
 #ifdef USE_ESP8266
 #include <pgmspace.h>
@@ -42,6 +43,9 @@
 #ifdef USE_ZWAVE_PROXY
 #include "esphome/components/zwave_proxy/zwave_proxy.h"
 #endif
+#ifdef USE_WATER_HEATER
+#include "esphome/components/water_heater/water_heater.h"
+#endif
 
 namespace esphome::api {
 
@@ -93,8 +97,7 @@ static const int CAMERA_STOP_STREAM = 5000;
     return;
 #endif  // USE_DEVICES
 
-APIConnection::APIConnection(std::unique_ptr<socket::Socket> sock, APIServer *parent)
-    : parent_(parent), initial_state_iterator_(this), list_entities_iterator_(this) {
+APIConnection::APIConnection(std::unique_ptr<socket::Socket> sock, APIServer *parent) : parent_(parent) {
 #if defined(USE_API_PLAINTEXT) && defined(USE_API_NOISE)
   auto &noise_ctx = parent->get_noise_ctx();
   if (noise_ctx.has_psk()) {
@@ -135,6 +138,7 @@ void APIConnection::start() {
 }
 
 APIConnection::~APIConnection() {
+  this->destroy_active_iterator_();
 #ifdef USE_BLUETOOTH_PROXY
   if (bluetooth_proxy::global_bluetooth_proxy->get_api_connection() == this) {
     bluetooth_proxy::global_bluetooth_proxy->unsubscribe_api_connection(this);
@@ -147,6 +151,32 @@ APIConnection::~APIConnection() {
 #endif
 }
 
+void APIConnection::destroy_active_iterator_() {
+  switch (this->active_iterator_) {
+    case ActiveIterator::LIST_ENTITIES:
+      this->iterator_storage_.list_entities.~ListEntitiesIterator();
+      break;
+    case ActiveIterator::INITIAL_STATE:
+      this->iterator_storage_.initial_state.~InitialStateIterator();
+      break;
+    case ActiveIterator::NONE:
+      break;
+  }
+  this->active_iterator_ = ActiveIterator::NONE;
+}
+
+void APIConnection::begin_iterator_(ActiveIterator type) {
+  this->destroy_active_iterator_();
+  this->active_iterator_ = type;
+  if (type == ActiveIterator::LIST_ENTITIES) {
+    new (&this->iterator_storage_.list_entities) ListEntitiesIterator(this);
+    this->iterator_storage_.list_entities.begin();
+  } else {
+    new (&this->iterator_storage_.initial_state) InitialStateIterator(this);
+    this->iterator_storage_.initial_state.begin();
+  }
+}
+
 void APIConnection::loop() {
   if (this->flags_.next_close) {
     // requested a disconnect
@@ -189,23 +219,35 @@ void APIConnection::loop() {
     this->process_batch_();
   }
 
-  if (!this->list_entities_iterator_.completed()) {
-    this->process_iterator_batch_(this->list_entities_iterator_);
-  } else if (!this->initial_state_iterator_.completed()) {
-    this->process_iterator_batch_(this->initial_state_iterator_);
-
-    // If we've completed initial states, process any remaining and clear the flag
-    if (this->initial_state_iterator_.completed()) {
-      // Process any remaining batched messages immediately
-      if (!this->deferred_batch_.empty()) {
-        this->process_batch_();
+  switch (this->active_iterator_) {
+    case ActiveIterator::LIST_ENTITIES:
+      if (this->iterator_storage_.list_entities.completed()) {
+        this->destroy_active_iterator_();
+        if (this->flags_.state_subscription) {
+          this->begin_iterator_(ActiveIterator::INITIAL_STATE);
+        }
+      } else {
+        this->process_iterator_batch_(this->iterator_storage_.list_entities);
       }
-      // Now that everything is sent, enable immediate sending for future state changes
-      this->flags_.should_try_send_immediately = true;
-      // Release excess memory from buffers that grew during initial sync
-      this->deferred_batch_.release_buffer();
-      this->helper_->release_buffers();
-    }
+      break;
+    case ActiveIterator::INITIAL_STATE:
+      if (this->iterator_storage_.initial_state.completed()) {
+        this->destroy_active_iterator_();
+        // Process any remaining batched messages immediately
+        if (!this->deferred_batch_.empty()) {
+          this->process_batch_();
+        }
+        // Now that everything is sent, enable immediate sending for future state changes
+        this->flags_.should_try_send_immediately = true;
+        // Release excess memory from buffers that grew during initial sync
+        this->deferred_batch_.release_buffer();
+        this->helper_->release_buffers();
+      } else {
+        this->process_iterator_batch_(this->iterator_storage_.initial_state);
+      }
+      break;
+    case ActiveIterator::NONE:
+      break;
   }
 
   if (this->flags_.sent_ping) {
@@ -229,33 +271,17 @@ void APIConnection::loop() {
     }
   }
 
-#ifdef USE_CAMERA
-  if (this->image_reader_ && this->image_reader_->available() && this->helper_->can_write_without_blocking()) {
-    uint32_t to_send = std::min((size_t) MAX_BATCH_PACKET_SIZE, this->image_reader_->available());
-    bool done = this->image_reader_->available() == to_send;
-
-    CameraImageResponse msg;
-    msg.key = camera::Camera::instance()->get_object_id_hash();
-    msg.set_data(this->image_reader_->peek_data_buffer(), to_send);
-    msg.done = done;
-#ifdef USE_DEVICES
-    msg.device_id = camera::Camera::instance()->get_device_id();
-#endif
-
-    if (this->send_message_(msg, CameraImageResponse::MESSAGE_TYPE)) {
-      this->image_reader_->consume_data(to_send);
-      if (done) {
-        this->image_reader_->return_image();
-      }
-    }
-  }
-#endif
-
 #ifdef USE_API_HOMEASSISTANT_STATES
   if (state_subs_at_ >= 0) {
     this->process_state_subscriptions_();
   }
 #endif
+
+#ifdef USE_CAMERA
+  // Process camera last - state updates are higher priority
+  // (missing a frame is fine, missing a state update is not)
+  this->try_send_camera_image_();
+#endif
 }
 
 bool APIConnection::send_disconnect_response(const DisconnectRequest &msg) {
@@ -448,7 +474,7 @@ void APIConnection::fan_command(const FanCommandRequest &msg) {
   if (msg.has_direction)
     call.set_direction(static_cast<fan::FanDirection>(msg.direction));
   if (msg.has_preset_mode)
-    call.set_preset_mode(msg.preset_mode);
+    call.set_preset_mode(reinterpret_cast<const char *>(msg.preset_mode), msg.preset_mode_len);
   call.perform();
 }
 #endif
@@ -713,11 +739,11 @@ void APIConnection::climate_command(const ClimateCommandRequest &msg) {
   if (msg.has_fan_mode)
     call.set_fan_mode(static_cast<climate::ClimateFanMode>(msg.fan_mode));
   if (msg.has_custom_fan_mode)
-    call.set_fan_mode(msg.custom_fan_mode);
+    call.set_fan_mode(reinterpret_cast<const char *>(msg.custom_fan_mode), msg.custom_fan_mode_len);
   if (msg.has_preset)
     call.set_preset(static_cast<climate::ClimatePreset>(msg.preset));
   if (msg.has_custom_preset)
-    call.set_preset(msg.custom_preset);
+    call.set_preset(reinterpret_cast<const char *>(msg.custom_preset), msg.custom_preset_len);
   if (msg.has_swing_mode)
     call.set_swing_mode(static_cast<climate::ClimateSwingMode>(msg.swing_mode));
   call.perform();
@@ -1058,6 +1084,36 @@ void APIConnection::media_player_command(const MediaPlayerCommandRequest &msg) {
 #endif
 
 #ifdef USE_CAMERA
+void APIConnection::try_send_camera_image_() {
+  if (!this->image_reader_)
+    return;
+
+  // Send as many chunks as possible without blocking
+  while (this->image_reader_->available()) {
+    if (!this->helper_->can_write_without_blocking())
+      return;
+
+    uint32_t to_send = std::min((size_t) MAX_BATCH_PACKET_SIZE, this->image_reader_->available());
+    bool done = this->image_reader_->available() == to_send;
+
+    CameraImageResponse msg;
+    msg.key = camera::Camera::instance()->get_object_id_hash();
+    msg.set_data(this->image_reader_->peek_data_buffer(), to_send);
+    msg.done = done;
+#ifdef USE_DEVICES
+    msg.device_id = camera::Camera::instance()->get_device_id();
+#endif
+
+    if (!this->send_message_(msg, CameraImageResponse::MESSAGE_TYPE)) {
+      return;  // Send failed, try again later
+    }
+    this->image_reader_->consume_data(to_send);
+    if (done) {
+      this->image_reader_->return_image();
+      return;
+    }
+  }
+}
 void APIConnection::set_camera_state(std::shared_ptr<camera::CameraImage> image) {
   if (!this->flags_.state_subscription)
     return;
@@ -1065,8 +1121,11 @@ void APIConnection::set_camera_state(std::shared_ptr<camera::CameraImage> image)
     return;
   if (this->image_reader_->available())
     return;
-  if (image->was_requested_by(esphome::camera::API_REQUESTER) || image->was_requested_by(esphome::camera::IDLE))
+  if (image->was_requested_by(esphome::camera::API_REQUESTER) || image->was_requested_by(esphome::camera::IDLE)) {
     this->image_reader_->set_image(std::move(image));
+    // Try to send immediately to reduce latency
+    this->try_send_camera_image_();
+  }
 }
 uint16_t APIConnection::try_send_camera_info(EntityBase *entity, APIConnection *conn, uint32_t remaining_size,
                                              bool is_single) {
@@ -1307,6 +1366,57 @@ void APIConnection::alarm_control_panel_command(const AlarmControlPanelCommandRe
 }
 #endif
 
+#ifdef USE_WATER_HEATER
+bool APIConnection::send_water_heater_state(water_heater::WaterHeater *water_heater) {
+  return this->send_message_smart_(water_heater, &APIConnection::try_send_water_heater_state,
+                                   WaterHeaterStateResponse::MESSAGE_TYPE, WaterHeaterStateResponse::ESTIMATED_SIZE);
+}
+uint16_t APIConnection::try_send_water_heater_state(EntityBase *entity, APIConnection *conn, uint32_t remaining_size,
+                                                    bool is_single) {
+  auto *wh = static_cast<water_heater::WaterHeater *>(entity);
+  WaterHeaterStateResponse resp;
+  resp.mode = static_cast<enums::WaterHeaterMode>(wh->get_mode());
+  resp.current_temperature = wh->get_current_temperature();
+  resp.target_temperature = wh->get_target_temperature();
+  resp.target_temperature_low = wh->get_target_temperature_low();
+  resp.target_temperature_high = wh->get_target_temperature_high();
+  resp.state = wh->get_state();
+  resp.key = wh->get_object_id_hash();
+
+  return encode_message_to_buffer(resp, WaterHeaterStateResponse::MESSAGE_TYPE, conn, remaining_size, is_single);
+}
+uint16_t APIConnection::try_send_water_heater_info(EntityBase *entity, APIConnection *conn, uint32_t remaining_size,
+                                                   bool is_single) {
+  auto *wh = static_cast<water_heater::WaterHeater *>(entity);
+  ListEntitiesWaterHeaterResponse msg;
+  auto traits = wh->get_traits();
+  msg.min_temperature = traits.get_min_temperature();
+  msg.max_temperature = traits.get_max_temperature();
+  msg.target_temperature_step = traits.get_target_temperature_step();
+  msg.supported_modes = &traits.get_supported_modes();
+  msg.supported_features = traits.get_feature_flags();
+  return fill_and_encode_entity_info(wh, msg, ListEntitiesWaterHeaterResponse::MESSAGE_TYPE, conn, remaining_size,
+                                     is_single);
+}
+
+void APIConnection::on_water_heater_command_request(const WaterHeaterCommandRequest &msg) {
+  ENTITY_COMMAND_MAKE_CALL(water_heater::WaterHeater, water_heater, water_heater)
+  if (msg.has_fields & enums::WATER_HEATER_COMMAND_HAS_MODE)
+    call.set_mode(static_cast<water_heater::WaterHeaterMode>(msg.mode));
+  if (msg.has_fields & enums::WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE)
+    call.set_target_temperature(msg.target_temperature);
+  if (msg.has_fields & enums::WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_LOW)
+    call.set_target_temperature_low(msg.target_temperature_low);
+  if (msg.has_fields & enums::WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_HIGH)
+    call.set_target_temperature_high(msg.target_temperature_high);
+  if (msg.has_fields & enums::WATER_HEATER_COMMAND_HAS_STATE) {
+    call.set_away((msg.state & water_heater::WATER_HEATER_STATE_AWAY) != 0);
+    call.set_on((msg.state & water_heater::WATER_HEATER_STATE_ON) != 0);
+  }
+  call.perform();
+}
+#endif
+
 #ifdef USE_EVENT
 void APIConnection::send_event(event::Event *event, const char *event_type) {
   this->send_message_smart_(event, MessageCreator(event_type), EventResponse::MESSAGE_TYPE,
@@ -1585,15 +1695,29 @@ bool APIConnection::send_device_info_response(const DeviceInfoRequest &msg) {
 
 #ifdef USE_API_HOMEASSISTANT_STATES
 void APIConnection::on_home_assistant_state_response(const HomeAssistantStateResponse &msg) {
-  for (auto &it : this->parent_->get_state_subs()) {
-    // Compare entity_id and attribute with message fields
-    bool entity_match = (strcmp(it.entity_id, msg.entity_id.c_str()) == 0);
-    bool attribute_match = (it.attribute != nullptr && strcmp(it.attribute, msg.attribute.c_str()) == 0) ||
-                           (it.attribute == nullptr && msg.attribute.empty());
+  // Skip if entity_id is empty (invalid message)
+  if (msg.entity_id_len == 0) {
+    return;
+  }
 
-    if (entity_match && attribute_match) {
-      it.callback(msg.state);
+  for (auto &it : this->parent_->get_state_subs()) {
+    // Compare entity_id: check length matches and content matches
+    size_t entity_id_len = strlen(it.entity_id);
+    if (entity_id_len != msg.entity_id_len || memcmp(it.entity_id, msg.entity_id, msg.entity_id_len) != 0) {
+      continue;
     }
+
+    // Compare attribute: either both have matching attribute, or both have none
+    size_t sub_attr_len = it.attribute != nullptr ? strlen(it.attribute) : 0;
+    if (sub_attr_len != msg.attribute_len ||
+        (sub_attr_len > 0 && memcmp(it.attribute, msg.attribute, sub_attr_len) != 0)) {
+      continue;
+    }
+
+    // Create temporary string for callback (callback takes const std::string &)
+    // Handle empty state (nullptr with len=0)
+    std::string state(msg.state_len > 0 ? reinterpret_cast<const char *>(msg.state) : "", msg.state_len);
+    it.callback(state);
   }
 }
 #endif
@@ -1669,13 +1793,13 @@ bool APIConnection::send_noise_encryption_set_key_response(const NoiseEncryption
   resp.success = false;
 
   psk_t psk{};
-  if (msg.key.empty()) {
+  if (msg.key_len == 0) {
     if (this->parent_->clear_noise_psk(true)) {
       resp.success = true;
     } else {
       ESP_LOGW(TAG, "Failed to clear encryption key");
     }
-  } else if (base64_decode(msg.key, psk.data(), psk.size()) != psk.size()) {
+  } else if (base64_decode(msg.key, msg.key_len, psk.data(), psk.size()) != psk.size()) {
     ESP_LOGW(TAG, "Invalid encryption key length");
   } else if (!this->parent_->save_noise_psk(psk, true)) {
     ESP_LOGW(TAG, "Failed to save encryption key");

esphome/components/api/api_connection.h

@@ -177,6 +177,11 @@ class APIConnection final : public APIServerConnection {
   void alarm_control_panel_command(const AlarmControlPanelCommandRequest &msg) override;
 #endif
 
+#ifdef USE_WATER_HEATER
+  bool send_water_heater_state(water_heater::WaterHeater *water_heater);
+  void on_water_heater_command_request(const WaterHeaterCommandRequest &msg) override;
+#endif
+
 #ifdef USE_EVENT
   void send_event(event::Event *event, const char *event_type);
 #endif
@@ -204,10 +209,14 @@ class APIConnection final : public APIServerConnection {
   bool send_disconnect_response(const DisconnectRequest &msg) override;
   bool send_ping_response(const PingRequest &msg) override;
   bool send_device_info_response(const DeviceInfoRequest &msg) override;
-  void list_entities(const ListEntitiesRequest &msg) override { this->list_entities_iterator_.begin(); }
+  void list_entities(const ListEntitiesRequest &msg) override { this->begin_iterator_(ActiveIterator::LIST_ENTITIES); }
   void subscribe_states(const SubscribeStatesRequest &msg) override {
     this->flags_.state_subscription = true;
-    this->initial_state_iterator_.begin();
+    // Start initial state iterator only if no iterator is active
+    // If list_entities is running, we'll start initial_state when it completes
+    if (this->active_iterator_ == ActiveIterator::NONE) {
+      this->begin_iterator_(ActiveIterator::INITIAL_STATE);
+    }
   }
   void subscribe_logs(const SubscribeLogsRequest &msg) override {
     this->flags_.log_subscription = msg.level;
@@ -293,6 +302,10 @@ class APIConnection final : public APIServerConnection {
   // Helper function to handle authentication completion
   void complete_authentication_();
 
+#ifdef USE_CAMERA
+  void try_send_camera_image_();
+#endif
+
 #ifdef USE_API_HOMEASSISTANT_STATES
   void process_state_subscriptions_();
 #endif
@@ -316,17 +329,10 @@ 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();
-    // Try to use static reference first to avoid allocation
-    StringRef static_ref = entity->get_object_id_ref_for_api_();
-    // Store dynamic string outside the if-else to maintain lifetime
-    std::string object_id;
-    if (!static_ref.empty()) {
-      msg.set_object_id(static_ref);
-    } else {
-      // Dynamic case - need to allocate
-      object_id = entity->get_object_id();
-      msg.set_object_id(StringRef(object_id));
-    }
+    // Get object_id with zero heap allocation
+    // Static case returns direct reference, dynamic case uses buffer
+    char object_id_buf[OBJECT_ID_MAX_LEN];
+    msg.set_object_id(entity->get_object_id_to(object_id_buf));
 
     if (entity->has_own_name()) {
       msg.set_name(entity->get_name());
@@ -462,6 +468,12 @@ class APIConnection final : public APIServerConnection {
   static uint16_t try_send_alarm_control_panel_info(EntityBase *entity, APIConnection *conn, uint32_t remaining_size,
                                                     bool is_single);
 #endif
+#ifdef USE_WATER_HEATER
+  static uint16_t try_send_water_heater_state(EntityBase *entity, APIConnection *conn, uint32_t remaining_size,
+                                              bool is_single);
+  static uint16_t try_send_water_heater_info(EntityBase *entity, APIConnection *conn, uint32_t remaining_size,
+                                             bool is_single);
+#endif
 #ifdef USE_EVENT
   static uint16_t try_send_event_response(event::Event *event, const char *event_type, APIConnection *conn,
                                           uint32_t remaining_size, bool is_single);
@@ -496,10 +508,22 @@ class APIConnection final : public APIServerConnection {
   std::unique_ptr<APIFrameHelper> helper_;
   APIServer *parent_;
 
-  // Group 2: Larger objects (must be 4-byte aligned)
-  // These contain vectors/pointers internally, so putting them early ensures good alignment
-  InitialStateIterator initial_state_iterator_;
-  ListEntitiesIterator list_entities_iterator_;
+  // Group 2: Iterator union (saves ~16 bytes vs separate iterators)
+  // These iterators are never active simultaneously - list_entities runs to completion
+  // before initial_state begins, so we use a union with explicit construction/destruction.
+  enum class ActiveIterator : uint8_t { NONE, LIST_ENTITIES, INITIAL_STATE };
+
+  union IteratorUnion {
+    ListEntitiesIterator list_entities;
+    InitialStateIterator initial_state;
+    // Constructor/destructor do nothing - use placement new/explicit destructor
+    IteratorUnion() {}
+    ~IteratorUnion() {}
+  } iterator_storage_;
+
+  // Helper methods for iterator lifecycle management
+  void destroy_active_iterator_();
+  void begin_iterator_(ActiveIterator type);
 #ifdef USE_CAMERA
   std::unique_ptr<camera::CameraImageReader> image_reader_;
 #endif
@@ -614,7 +638,9 @@ class APIConnection final : public APIServerConnection {
   // 2-byte types immediately after flags_ (no padding between them)
   uint16_t client_api_version_major_{0};
   uint16_t client_api_version_minor_{0};
-  // Total: 2 (flags) + 2 + 2 = 6 bytes, then 2 bytes padding to next 4-byte boundary
+  // 1-byte type to fill padding
+  ActiveIterator active_iterator_{ActiveIterator::NONE};
+  // Total: 2 (flags) + 2 + 2 + 1 = 7 bytes, then 1 byte padding to next 4-byte boundary
 
   uint32_t get_batch_delay_ms_() const;
   // Message will use 8 more bytes than the minimum size, and typical

esphome/components/api/api_pb2.cpp

@@ -447,9 +447,12 @@ bool FanCommandRequest::decode_varint(uint32_t field_id, ProtoVarInt value) {
 }
 bool FanCommandRequest::decode_length(uint32_t field_id, ProtoLengthDelimited value) {
   switch (field_id) {
-    case 13:
-      this->preset_mode = value.as_string();
+    case 13: {
+      // Use raw data directly to avoid allocation
+      this->preset_mode = value.data();
+      this->preset_mode_len = value.size();
       break;
+    }
     default:
       return false;
   }
@@ -855,9 +858,12 @@ void SubscribeLogsResponse::calculate_size(ProtoSize &size) const {
 #ifdef USE_API_NOISE
 bool NoiseEncryptionSetKeyRequest::decode_length(uint32_t field_id, ProtoLengthDelimited value) {
   switch (field_id) {
-    case 1:
-      this->key = value.as_string();
+    case 1: {
+      // Use raw data directly to avoid allocation
+      this->key = value.data();
+      this->key_len = value.size();
       break;
+    }
     default:
       return false;
   }
@@ -960,15 +966,24 @@ void SubscribeHomeAssistantStateResponse::calculate_size(ProtoSize &size) const
 }
 bool HomeAssistantStateResponse::decode_length(uint32_t field_id, ProtoLengthDelimited value) {
   switch (field_id) {
-    case 1:
-      this->entity_id = value.as_string();
+    case 1: {
+      // Use raw data directly to avoid allocation
+      this->entity_id = value.data();
+      this->entity_id_len = value.size();
       break;
-    case 2:
-      this->state = value.as_string();
+    }
+    case 2: {
+      // Use raw data directly to avoid allocation
+      this->state = value.data();
+      this->state_len = value.size();
       break;
-    case 3:
-      this->attribute = value.as_string();
+    }
+    case 3: {
+      // Use raw data directly to avoid allocation
+      this->attribute = value.data();
+      this->attribute_len = value.size();
       break;
+    }
     default:
       return false;
   }
@@ -1392,12 +1407,18 @@ bool ClimateCommandRequest::decode_varint(uint32_t field_id, ProtoVarInt value)
 }
 bool ClimateCommandRequest::decode_length(uint32_t field_id, ProtoLengthDelimited value) {
   switch (field_id) {
-    case 17:
-      this->custom_fan_mode = value.as_string();
+    case 17: {
+      // Use raw data directly to avoid allocation
+      this->custom_fan_mode = value.data();
+      this->custom_fan_mode_len = value.size();
       break;
-    case 21:
-      this->custom_preset = value.as_string();
+    }
+    case 21: {
+      // Use raw data directly to avoid allocation
+      this->custom_preset = value.data();
+      this->custom_preset_len = value.size();
       break;
+    }
     default:
       return false;
   }
@@ -1426,6 +1447,114 @@ bool ClimateCommandRequest::decode_32bit(uint32_t field_id, Proto32Bit value) {
   return true;
 }
 #endif
+#ifdef USE_WATER_HEATER
+void ListEntitiesWaterHeaterResponse::encode(ProtoWriteBuffer buffer) const {
+  buffer.encode_string(1, this->object_id_ref_);
+  buffer.encode_fixed32(2, this->key);
+  buffer.encode_string(3, this->name_ref_);
+#ifdef USE_ENTITY_ICON
+  buffer.encode_string(4, this->icon_ref_);
+#endif
+  buffer.encode_bool(5, this->disabled_by_default);
+  buffer.encode_uint32(6, static_cast<uint32_t>(this->entity_category));
+#ifdef USE_DEVICES
+  buffer.encode_uint32(7, this->device_id);
+#endif
+  buffer.encode_float(8, this->min_temperature);
+  buffer.encode_float(9, this->max_temperature);
+  buffer.encode_float(10, this->target_temperature_step);
+  for (const auto &it : *this->supported_modes) {
+    buffer.encode_uint32(11, static_cast<uint32_t>(it), true);
+  }
+  buffer.encode_uint32(12, this->supported_features);
+}
+void ListEntitiesWaterHeaterResponse::calculate_size(ProtoSize &size) const {
+  size.add_length(1, this->object_id_ref_.size());
+  size.add_fixed32(1, this->key);
+  size.add_length(1, this->name_ref_.size());
+#ifdef USE_ENTITY_ICON
+  size.add_length(1, this->icon_ref_.size());
+#endif
+  size.add_bool(1, this->disabled_by_default);
+  size.add_uint32(1, static_cast<uint32_t>(this->entity_category));
+#ifdef USE_DEVICES
+  size.add_uint32(1, this->device_id);
+#endif
+  size.add_float(1, this->min_temperature);
+  size.add_float(1, this->max_temperature);
+  size.add_float(1, this->target_temperature_step);
+  if (!this->supported_modes->empty()) {
+    for (const auto &it : *this->supported_modes) {
+      size.add_uint32_force(1, static_cast<uint32_t>(it));
+    }
+  }
+  size.add_uint32(1, this->supported_features);
+}
+void WaterHeaterStateResponse::encode(ProtoWriteBuffer buffer) const {
+  buffer.encode_fixed32(1, this->key);
+  buffer.encode_float(2, this->current_temperature);
+  buffer.encode_float(3, this->target_temperature);
+  buffer.encode_uint32(4, static_cast<uint32_t>(this->mode));
+#ifdef USE_DEVICES
+  buffer.encode_uint32(5, this->device_id);
+#endif
+  buffer.encode_uint32(6, this->state);
+  buffer.encode_float(7, this->target_temperature_low);
+  buffer.encode_float(8, this->target_temperature_high);
+}
+void WaterHeaterStateResponse::calculate_size(ProtoSize &size) const {
+  size.add_fixed32(1, this->key);
+  size.add_float(1, this->current_temperature);
+  size.add_float(1, this->target_temperature);
+  size.add_uint32(1, static_cast<uint32_t>(this->mode));
+#ifdef USE_DEVICES
+  size.add_uint32(1, this->device_id);
+#endif
+  size.add_uint32(1, this->state);
+  size.add_float(1, this->target_temperature_low);
+  size.add_float(1, this->target_temperature_high);
+}
+bool WaterHeaterCommandRequest::decode_varint(uint32_t field_id, ProtoVarInt value) {
+  switch (field_id) {
+    case 2:
+      this->has_fields = value.as_uint32();
+      break;
+    case 3:
+      this->mode = static_cast<enums::WaterHeaterMode>(value.as_uint32());
+      break;
+#ifdef USE_DEVICES
+    case 5:
+      this->device_id = value.as_uint32();
+      break;
+#endif
+    case 6:
+      this->state = value.as_uint32();
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+bool WaterHeaterCommandRequest::decode_32bit(uint32_t field_id, Proto32Bit value) {
+  switch (field_id) {
+    case 1:
+      this->key = value.as_fixed32();
+      break;
+    case 4:
+      this->target_temperature = value.as_float();
+      break;
+    case 7:
+      this->target_temperature_low = value.as_float();
+      break;
+    case 8:
+      this->target_temperature_high = value.as_float();
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+#endif
 #ifdef USE_NUMBER
 void ListEntitiesNumberResponse::encode(ProtoWriteBuffer buffer) const {
   buffer.encode_string(1, this->object_id_ref_);

esphome/components/api/api_pb2.h

@@ -129,6 +129,25 @@ enum ClimatePreset : uint32_t {
   CLIMATE_PRESET_ACTIVITY = 7,
 };
 #endif
+#ifdef USE_WATER_HEATER
+enum WaterHeaterMode : uint32_t {
+  WATER_HEATER_MODE_OFF = 0,
+  WATER_HEATER_MODE_ECO = 1,
+  WATER_HEATER_MODE_ELECTRIC = 2,
+  WATER_HEATER_MODE_PERFORMANCE = 3,
+  WATER_HEATER_MODE_HIGH_DEMAND = 4,
+  WATER_HEATER_MODE_HEAT_PUMP = 5,
+  WATER_HEATER_MODE_GAS = 6,
+};
+#endif
+enum WaterHeaterCommandHasField : uint32_t {
+  WATER_HEATER_COMMAND_HAS_NONE = 0,
+  WATER_HEATER_COMMAND_HAS_MODE = 1,
+  WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE = 2,
+  WATER_HEATER_COMMAND_HAS_STATE = 4,
+  WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_LOW = 8,
+  WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_HIGH = 16,
+};
 #ifdef USE_NUMBER
 enum NumberMode : uint32_t {
   NUMBER_MODE_AUTO = 0,
@@ -765,7 +784,7 @@ class FanStateResponse final : public StateResponseProtoMessage {
 class FanCommandRequest final : public CommandProtoMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 31;
-  static constexpr uint8_t ESTIMATED_SIZE = 38;
+  static constexpr uint8_t ESTIMATED_SIZE = 48;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "fan_command_request"; }
 #endif
@@ -778,7 +797,8 @@ class FanCommandRequest final : public CommandProtoMessage {
   bool has_speed_level{false};
   int32_t speed_level{0};
   bool has_preset_mode{false};
-  std::string preset_mode{};
+  const uint8_t *preset_mode{nullptr};
+  uint16_t preset_mode_len{0};
 #ifdef HAS_PROTO_MESSAGE_DUMP
   void dump_to(std::string &out) const override;
 #endif
@@ -1053,11 +1073,12 @@ 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
-  std::string key{};
+  const uint8_t *key{nullptr};
+  uint16_t key_len{0};
 #ifdef HAS_PROTO_MESSAGE_DUMP
   void dump_to(std::string &out) const override;
 #endif
@@ -1201,13 +1222,16 @@ class SubscribeHomeAssistantStateResponse final : public ProtoMessage {
 class HomeAssistantStateResponse final : public ProtoDecodableMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 40;
-  static constexpr uint8_t ESTIMATED_SIZE = 27;
+  static constexpr uint8_t ESTIMATED_SIZE = 57;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "home_assistant_state_response"; }
 #endif
-  std::string entity_id{};
-  std::string state{};
-  std::string attribute{};
+  const uint8_t *entity_id{nullptr};
+  uint16_t entity_id_len{0};
+  const uint8_t *state{nullptr};
+  uint16_t state_len{0};
+  const uint8_t *attribute{nullptr};
+  uint16_t attribute_len{0};
 #ifdef HAS_PROTO_MESSAGE_DUMP
   void dump_to(std::string &out) const override;
 #endif
@@ -1475,7 +1499,7 @@ class ClimateStateResponse final : public StateResponseProtoMessage {
 class ClimateCommandRequest final : public CommandProtoMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 48;
-  static constexpr uint8_t ESTIMATED_SIZE = 84;
+  static constexpr uint8_t ESTIMATED_SIZE = 104;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "climate_command_request"; }
 #endif
@@ -1492,11 +1516,13 @@ class ClimateCommandRequest final : public CommandProtoMessage {
   bool has_swing_mode{false};
   enums::ClimateSwingMode swing_mode{};
   bool has_custom_fan_mode{false};
-  std::string custom_fan_mode{};
+  const uint8_t *custom_fan_mode{nullptr};
+  uint16_t custom_fan_mode_len{0};
   bool has_preset{false};
   enums::ClimatePreset preset{};
   bool has_custom_preset{false};
-  std::string custom_preset{};
+  const uint8_t *custom_preset{nullptr};
+  uint16_t custom_preset_len{0};
   bool has_target_humidity{false};
   float target_humidity{0.0f};
 #ifdef HAS_PROTO_MESSAGE_DUMP
@@ -1509,6 +1535,70 @@ class ClimateCommandRequest final : public CommandProtoMessage {
   bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
 };
 #endif
+#ifdef USE_WATER_HEATER
+class ListEntitiesWaterHeaterResponse final : public InfoResponseProtoMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 132;
+  static constexpr uint8_t ESTIMATED_SIZE = 63;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "list_entities_water_heater_response"; }
+#endif
+  float min_temperature{0.0f};
+  float max_temperature{0.0f};
+  float target_temperature_step{0.0f};
+  const water_heater::WaterHeaterModeMask *supported_modes{};
+  uint32_t supported_features{0};
+  void encode(ProtoWriteBuffer buffer) const override;
+  void calculate_size(ProtoSize &size) const override;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  void dump_to(std::string &out) const override;
+#endif
+
+ protected:
+};
+class WaterHeaterStateResponse final : public StateResponseProtoMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 133;
+  static constexpr uint8_t ESTIMATED_SIZE = 35;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "water_heater_state_response"; }
+#endif
+  float current_temperature{0.0f};
+  float target_temperature{0.0f};
+  enums::WaterHeaterMode mode{};
+  uint32_t state{0};
+  float target_temperature_low{0.0f};
+  float target_temperature_high{0.0f};
+  void encode(ProtoWriteBuffer buffer) const override;
+  void calculate_size(ProtoSize &size) const override;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  void dump_to(std::string &out) const override;
+#endif
+
+ protected:
+};
+class WaterHeaterCommandRequest final : public CommandProtoMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 134;
+  static constexpr uint8_t ESTIMATED_SIZE = 34;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "water_heater_command_request"; }
+#endif
+  uint32_t has_fields{0};
+  enums::WaterHeaterMode mode{};
+  float target_temperature{0.0f};
+  uint32_t state{0};
+  float target_temperature_low{0.0f};
+  float target_temperature_high{0.0f};
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  void dump_to(std::string &out) const override;
+#endif
+
+ protected:
+  bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
+  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+};
+#endif
 #ifdef USE_NUMBER
 class ListEntitiesNumberResponse final : public InfoResponseProtoMessage {
  public:

esphome/components/api/api_pb2_dump.cpp

@@ -348,6 +348,47 @@ template<> const char *proto_enum_to_string<enums::ClimatePreset>(enums::Climate
   }
 }
 #endif
+#ifdef USE_WATER_HEATER
+template<> const char *proto_enum_to_string<enums::WaterHeaterMode>(enums::WaterHeaterMode value) {
+  switch (value) {
+    case enums::WATER_HEATER_MODE_OFF:
+      return "WATER_HEATER_MODE_OFF";
+    case enums::WATER_HEATER_MODE_ECO:
+      return "WATER_HEATER_MODE_ECO";
+    case enums::WATER_HEATER_MODE_ELECTRIC:
+      return "WATER_HEATER_MODE_ELECTRIC";
+    case enums::WATER_HEATER_MODE_PERFORMANCE:
+      return "WATER_HEATER_MODE_PERFORMANCE";
+    case enums::WATER_HEATER_MODE_HIGH_DEMAND:
+      return "WATER_HEATER_MODE_HIGH_DEMAND";
+    case enums::WATER_HEATER_MODE_HEAT_PUMP:
+      return "WATER_HEATER_MODE_HEAT_PUMP";
+    case enums::WATER_HEATER_MODE_GAS:
+      return "WATER_HEATER_MODE_GAS";
+    default:
+      return "UNKNOWN";
+  }
+}
+#endif
+template<>
+const char *proto_enum_to_string<enums::WaterHeaterCommandHasField>(enums::WaterHeaterCommandHasField value) {
+  switch (value) {
+    case enums::WATER_HEATER_COMMAND_HAS_NONE:
+      return "WATER_HEATER_COMMAND_HAS_NONE";
+    case enums::WATER_HEATER_COMMAND_HAS_MODE:
+      return "WATER_HEATER_COMMAND_HAS_MODE";
+    case enums::WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE:
+      return "WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE";
+    case enums::WATER_HEATER_COMMAND_HAS_STATE:
+      return "WATER_HEATER_COMMAND_HAS_STATE";
+    case enums::WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_LOW:
+      return "WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_LOW";
+    case enums::WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_HIGH:
+      return "WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_HIGH";
+    default:
+      return "UNKNOWN";
+  }
+}
 #ifdef USE_NUMBER
 template<> const char *proto_enum_to_string<enums::NumberMode>(enums::NumberMode value) {
   switch (value) {
@@ -923,7 +964,9 @@ void FanCommandRequest::dump_to(std::string &out) const {
   dump_field(out, "has_speed_level", this->has_speed_level);
   dump_field(out, "speed_level", this->speed_level);
   dump_field(out, "has_preset_mode", this->has_preset_mode);
-  dump_field(out, "preset_mode", this->preset_mode);
+  out.append("  preset_mode: ");
+  out.append(format_hex_pretty(this->preset_mode, this->preset_mode_len));
+  out.append("\n");
 #ifdef USE_DEVICES
   dump_field(out, "device_id", this->device_id);
 #endif
@@ -1113,7 +1156,7 @@ void SubscribeLogsResponse::dump_to(std::string &out) const {
 void NoiseEncryptionSetKeyRequest::dump_to(std::string &out) const {
   MessageDumpHelper helper(out, "NoiseEncryptionSetKeyRequest");
   out.append("  key: ");
-  out.append(format_hex_pretty(reinterpret_cast<const uint8_t *>(this->key.data()), this->key.size()));
+  out.append(format_hex_pretty(this->key, this->key_len));
   out.append("\n");
 }
 void NoiseEncryptionSetKeyResponse::dump_to(std::string &out) const { dump_field(out, "success", this->success); }
@@ -1182,9 +1225,15 @@ void SubscribeHomeAssistantStateResponse::dump_to(std::string &out) const {
 }
 void HomeAssistantStateResponse::dump_to(std::string &out) const {
   MessageDumpHelper helper(out, "HomeAssistantStateResponse");
-  dump_field(out, "entity_id", this->entity_id);
-  dump_field(out, "state", this->state);
-  dump_field(out, "attribute", this->attribute);
+  out.append("  entity_id: ");
+  out.append(format_hex_pretty(this->entity_id, this->entity_id_len));
+  out.append("\n");
+  out.append("  state: ");
+  out.append(format_hex_pretty(this->state, this->state_len));
+  out.append("\n");
+  out.append("  attribute: ");
+  out.append(format_hex_pretty(this->attribute, this->attribute_len));
+  out.append("\n");
 }
 #endif
 void GetTimeRequest::dump_to(std::string &out) const { out.append("GetTimeRequest {}"); }
@@ -1374,11 +1423,15 @@ void ClimateCommandRequest::dump_to(std::string &out) const {
   dump_field(out, "has_swing_mode", this->has_swing_mode);
   dump_field(out, "swing_mode", static_cast<enums::ClimateSwingMode>(this->swing_mode));
   dump_field(out, "has_custom_fan_mode", this->has_custom_fan_mode);
-  dump_field(out, "custom_fan_mode", this->custom_fan_mode);
+  out.append("  custom_fan_mode: ");
+  out.append(format_hex_pretty(this->custom_fan_mode, this->custom_fan_mode_len));
+  out.append("\n");
   dump_field(out, "has_preset", this->has_preset);
   dump_field(out, "preset", static_cast<enums::ClimatePreset>(this->preset));
   dump_field(out, "has_custom_preset", this->has_custom_preset);
-  dump_field(out, "custom_preset", this->custom_preset);
+  out.append("  custom_preset: ");
+  out.append(format_hex_pretty(this->custom_preset, this->custom_preset_len));
+  out.append("\n");
   dump_field(out, "has_target_humidity", this->has_target_humidity);
   dump_field(out, "target_humidity", this->target_humidity);
 #ifdef USE_DEVICES
@@ -1386,6 +1439,55 @@ void ClimateCommandRequest::dump_to(std::string &out) const {
 #endif
 }
 #endif
+#ifdef USE_WATER_HEATER
+void ListEntitiesWaterHeaterResponse::dump_to(std::string &out) const {
+  MessageDumpHelper helper(out, "ListEntitiesWaterHeaterResponse");
+  dump_field(out, "object_id", this->object_id_ref_);
+  dump_field(out, "key", this->key);
+  dump_field(out, "name", this->name_ref_);
+#ifdef USE_ENTITY_ICON
+  dump_field(out, "icon", this->icon_ref_);
+#endif
+  dump_field(out, "disabled_by_default", this->disabled_by_default);
+  dump_field(out, "entity_category", static_cast<enums::EntityCategory>(this->entity_category));
+#ifdef USE_DEVICES
+  dump_field(out, "device_id", this->device_id);
+#endif
+  dump_field(out, "min_temperature", this->min_temperature);
+  dump_field(out, "max_temperature", this->max_temperature);
+  dump_field(out, "target_temperature_step", this->target_temperature_step);
+  for (const auto &it : *this->supported_modes) {
+    dump_field(out, "supported_modes", static_cast<enums::WaterHeaterMode>(it), 4);
+  }
+  dump_field(out, "supported_features", this->supported_features);
+}
+void WaterHeaterStateResponse::dump_to(std::string &out) const {
+  MessageDumpHelper helper(out, "WaterHeaterStateResponse");
+  dump_field(out, "key", this->key);
+  dump_field(out, "current_temperature", this->current_temperature);
+  dump_field(out, "target_temperature", this->target_temperature);
+  dump_field(out, "mode", static_cast<enums::WaterHeaterMode>(this->mode));
+#ifdef USE_DEVICES
+  dump_field(out, "device_id", this->device_id);
+#endif
+  dump_field(out, "state", this->state);
+  dump_field(out, "target_temperature_low", this->target_temperature_low);
+  dump_field(out, "target_temperature_high", this->target_temperature_high);
+}
+void WaterHeaterCommandRequest::dump_to(std::string &out) const {
+  MessageDumpHelper helper(out, "WaterHeaterCommandRequest");
+  dump_field(out, "key", this->key);
+  dump_field(out, "has_fields", this->has_fields);
+  dump_field(out, "mode", static_cast<enums::WaterHeaterMode>(this->mode));
+  dump_field(out, "target_temperature", this->target_temperature);
+#ifdef USE_DEVICES
+  dump_field(out, "device_id", this->device_id);
+#endif
+  dump_field(out, "state", this->state);
+  dump_field(out, "target_temperature_low", this->target_temperature_low);
+  dump_field(out, "target_temperature_high", this->target_temperature_high);
+}
+#endif
 #ifdef USE_NUMBER
 void ListEntitiesNumberResponse::dump_to(std::string &out) const {
   MessageDumpHelper helper(out, "ListEntitiesNumberResponse");

esphome/components/api/api_pb2_includes.h

@@ -10,6 +10,10 @@
 #include "esphome/components/climate/climate_traits.h"
 #endif
 
+#ifdef USE_WATER_HEATER
+#include "esphome/components/water_heater/water_heater.h"
+#endif
+
 #ifdef USE_LIGHT
 #include "esphome/components/light/light_traits.h"
 #endif

esphome/components/api/api_pb2_service.cpp

@@ -621,6 +621,17 @@ void APIServerConnectionBase::read_message(uint32_t msg_size, uint32_t msg_type,
       this->on_homeassistant_action_response(msg);
       break;
     }
+#endif
+#ifdef USE_WATER_HEATER
+    case WaterHeaterCommandRequest::MESSAGE_TYPE: {
+      WaterHeaterCommandRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      ESP_LOGVV(TAG, "on_water_heater_command_request: %s", msg.dump().c_str());
+#endif
+      this->on_water_heater_command_request(msg);
+      break;
+    }
 #endif
     default:
       break;

esphome/components/api/api_pb2_service.h

@@ -91,6 +91,10 @@ class APIServerConnectionBase : public ProtoService {
   virtual void on_climate_command_request(const ClimateCommandRequest &value){};
 #endif
 
+#ifdef USE_WATER_HEATER
+  virtual void on_water_heater_command_request(const WaterHeaterCommandRequest &value){};
+#endif
+
 #ifdef USE_NUMBER
   virtual void on_number_command_request(const NumberCommandRequest &value){};
 #endif

esphome/components/api/api_server.cpp

@@ -338,6 +338,10 @@ API_DISPATCH_UPDATE(valve::Valve, valve)
 API_DISPATCH_UPDATE(media_player::MediaPlayer, media_player)
 #endif
 
+#ifdef USE_WATER_HEATER
+API_DISPATCH_UPDATE(water_heater::WaterHeater, water_heater)
+#endif
+
 #ifdef USE_EVENT
 // Event is a special case - unlike other entities with simple state fields,
 // events store their state in a member accessed via obj->get_last_event_type()

esphome/components/api/api_server.h

@@ -133,6 +133,9 @@ class APIServer : public Component,
 #ifdef USE_MEDIA_PLAYER
   void on_media_player_update(media_player::MediaPlayer *obj) override;
 #endif
+#ifdef USE_WATER_HEATER
+  void on_water_heater_update(water_heater::WaterHeater *obj) override;
+#endif
 #ifdef USE_API_HOMEASSISTANT_SERVICES
   void send_homeassistant_action(const HomeassistantActionRequest &call);
 

esphome/components/api/list_entities.cpp

@@ -73,6 +73,9 @@ LIST_ENTITIES_HANDLER(media_player, media_player::MediaPlayer, ListEntitiesMedia
 LIST_ENTITIES_HANDLER(alarm_control_panel, alarm_control_panel::AlarmControlPanel,
                       ListEntitiesAlarmControlPanelResponse)
 #endif
+#ifdef USE_WATER_HEATER
+LIST_ENTITIES_HANDLER(water_heater, water_heater::WaterHeater, ListEntitiesWaterHeaterResponse)
+#endif
 #ifdef USE_EVENT
 LIST_ENTITIES_HANDLER(event, event::Event, ListEntitiesEventResponse)
 #endif

esphome/components/api/list_entities.h

@@ -82,6 +82,9 @@ class ListEntitiesIterator : public ComponentIterator {
 #ifdef USE_ALARM_CONTROL_PANEL
   bool on_alarm_control_panel(alarm_control_panel::AlarmControlPanel *entity) override;
 #endif
+#ifdef USE_WATER_HEATER
+  bool on_water_heater(water_heater::WaterHeater *entity) override;
+#endif
 #ifdef USE_EVENT
   bool on_event(event::Event *entity) override;
 #endif

esphome/components/api/subscribe_state.cpp

@@ -60,6 +60,9 @@ INITIAL_STATE_HANDLER(media_player, media_player::MediaPlayer)
 #ifdef USE_ALARM_CONTROL_PANEL
 INITIAL_STATE_HANDLER(alarm_control_panel, alarm_control_panel::AlarmControlPanel)
 #endif
+#ifdef USE_WATER_HEATER
+INITIAL_STATE_HANDLER(water_heater, water_heater::WaterHeater)
+#endif
 #ifdef USE_UPDATE
 INITIAL_STATE_HANDLER(update, update::UpdateEntity)
 #endif

esphome/components/api/subscribe_state.h

@@ -76,6 +76,9 @@ class InitialStateIterator : public ComponentIterator {
 #ifdef USE_ALARM_CONTROL_PANEL
   bool on_alarm_control_panel(alarm_control_panel::AlarmControlPanel *entity) override;
 #endif
+#ifdef USE_WATER_HEATER
+  bool on_water_heater(water_heater::WaterHeater *entity) override;
+#endif
 #ifdef USE_EVENT
   bool on_event(event::Event *event) override { return true; };
 #endif