Merge branch 'dev' into api-flash-string-progmem

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

esphome/codegen.py

@@ -11,6 +11,7 @@
 from esphome.cpp_generator import (  # noqa: F401
     ArrayInitializer,
     Expression,
+    FlashStringLiteral,
     LineComment,
     LogStringLiteral,
     MockObj,

esphome/components/api/__init__.py

@@ -524,24 +524,31 @@ async def homeassistant_service_to_code(
     cg.add_define("USE_API_HOMEASSISTANT_SERVICES")
     serv = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, serv, False)
-    templ = await cg.templatable(config[CONF_ACTION], args, None)
+    templ = await cg.templatable(config[CONF_ACTION], args, cg.std_string)
     cg.add(var.set_service(templ))
 
     # Initialize FixedVectors with exact sizes from config
     cg.add(var.init_data(len(config[CONF_DATA])))
     for key, value in config[CONF_DATA].items():
+        # output_type=None because lambdas can return non-string types (int,
+        # float, char*) that TemplatableStringValue converts via to_string.
+        # Static strings are manually wrapped for PROGMEM on ESP8266.
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data(key, templ))
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
+        cg.add(var.add_data(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_data_template(len(config[CONF_DATA_TEMPLATE])))
     for key, value in config[CONF_DATA_TEMPLATE].items():
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data_template(key, templ))
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
+        cg.add(var.add_data_template(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_variable(key, templ))
+        cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
     if on_error := config.get(CONF_ON_ERROR):
         cg.add_define("USE_API_HOMEASSISTANT_ACTION_RESPONSES")
@@ -609,24 +616,31 @@ async def homeassistant_event_to_code(config, action_id, template_arg, args):
     cg.add_define("USE_API_HOMEASSISTANT_SERVICES")
     serv = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, serv, True)
-    templ = await cg.templatable(config[CONF_EVENT], args, None)
+    templ = await cg.templatable(config[CONF_EVENT], args, cg.std_string)
     cg.add(var.set_service(templ))
 
     # Initialize FixedVectors with exact sizes from config
     cg.add(var.init_data(len(config[CONF_DATA])))
     for key, value in config[CONF_DATA].items():
+        # output_type=None because lambdas can return non-string types (int,
+        # float, char*) that TemplatableStringValue converts via to_string.
+        # Static strings are manually wrapped for PROGMEM on ESP8266.
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data(key, templ))
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
+        cg.add(var.add_data(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_data_template(len(config[CONF_DATA_TEMPLATE])))
     for key, value in config[CONF_DATA_TEMPLATE].items():
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data_template(key, templ))
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
+        cg.add(var.add_data_template(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_variable(key, templ))
+        cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
     return var
 
@@ -649,11 +663,11 @@ async def homeassistant_tag_scanned_to_code(config, action_id, template_arg, arg
     cg.add_define("USE_API_HOMEASSISTANT_SERVICES")
     serv = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, serv, True)
-    cg.add(var.set_service("esphome.tag_scanned"))
+    cg.add(var.set_service(cg.FlashStringLiteral("esphome.tag_scanned")))
     # Initialize FixedVector with exact size (1 data field)
     cg.add(var.init_data(1))
     templ = await cg.templatable(config[CONF_TAG], args, cg.std_string)
-    cg.add(var.add_data("tag_id", templ))
+    cg.add(var.add_data(cg.FlashStringLiteral("tag_id"), templ))
     return var
 
 

esphome/components/api/api_connection.h

@@ -28,7 +28,7 @@ static constexpr size_t MAX_INITIAL_PER_BATCH = 34;         // For clients >= AP
 static_assert(MAX_MESSAGES_PER_BATCH >= MAX_INITIAL_PER_BATCH,
               "MAX_MESSAGES_PER_BATCH must be >= MAX_INITIAL_PER_BATCH");
 
-class APIConnection final : public APIServerConnection {
+class APIConnection final : public APIServerConnectionBase {
  public:
   friend class APIServer;
   friend class ListEntitiesIterator;

esphome/components/api/api_pb2_service.cpp

@@ -21,6 +21,23 @@ void APIServerConnectionBase::log_receive_message_(const LogString *name) {
 #endif
 
 void APIServerConnectionBase::read_message(uint32_t msg_size, uint32_t msg_type, const uint8_t *msg_data) {
+  // Check authentication/connection requirements
+  switch (msg_type) {
+    case HelloRequest::MESSAGE_TYPE:       // No setup required
+    case DisconnectRequest::MESSAGE_TYPE:  // No setup required
+    case PingRequest::MESSAGE_TYPE:        // No setup required
+      break;
+    case DeviceInfoRequest::MESSAGE_TYPE:  // Connection setup only
+      if (!this->check_connection_setup_()) {
+        return;
+      }
+      break;
+    default:
+      if (!this->check_authenticated_()) {
+        return;
+      }
+      break;
+  }
   switch (msg_type) {
     case HelloRequest::MESSAGE_TYPE: {
       HelloRequest msg;
@@ -623,28 +640,4 @@ void APIServerConnectionBase::read_message(uint32_t msg_size, uint32_t msg_type,
   }
 }
 
-void APIServerConnection::read_message(uint32_t msg_size, uint32_t msg_type, const uint8_t *msg_data) {
-  // Check authentication/connection requirements for messages
-  switch (msg_type) {
-    case HelloRequest::MESSAGE_TYPE:       // No setup required
-    case DisconnectRequest::MESSAGE_TYPE:  // No setup required
-    case PingRequest::MESSAGE_TYPE:        // No setup required
-      break;                               // Skip all checks for these messages
-    case DeviceInfoRequest::MESSAGE_TYPE:  // Connection setup only
-      if (!this->check_connection_setup_()) {
-        return;  // Connection not setup
-      }
-      break;
-    default:
-      // All other messages require authentication (which includes connection check)
-      if (!this->check_authenticated_()) {
-        return;  // Authentication failed
-      }
-      break;
-  }
-
-  // Call base implementation to process the message
-  APIServerConnectionBase::read_message(msg_size, msg_type, msg_data);
-}
-
 }  // namespace esphome::api

esphome/components/api/api_pb2_service.h

@@ -228,9 +228,4 @@ class APIServerConnectionBase : public ProtoService {
   void read_message(uint32_t msg_size, uint32_t msg_type, const uint8_t *msg_data) override;
 };
 
-class APIServerConnection : public APIServerConnectionBase {
- protected:
-  void read_message(uint32_t msg_size, uint32_t msg_type, const uint8_t *msg_data) override;
-};
-
 }  // namespace esphome::api

esphome/components/api/homeassistant_service.h

@@ -25,7 +25,9 @@ template<typename... X> class TemplatableStringValue : public TemplatableValue<s
 
  private:
   // Helper to convert value to string - handles the case where value is already a string
-  template<typename T> static std::string value_to_string(T &&val) { return to_string(std::forward<T>(val)); }
+  template<typename T> static std::string value_to_string(T &&val) {
+    return to_string(std::forward<T>(val));  // NOLINT
+  }
 
   // Overloads for string types - needed because std::to_string doesn't support them
   static std::string value_to_string(char *val) {
@@ -126,6 +128,20 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
     this->add_kv_(this->variables_, key, std::forward<V>(value));
   }
 
+#ifdef USE_ESP8266
+  // On ESP8266, ESPHOME_F() returns __FlashStringHelper* (PROGMEM pointer).
+  // Store as const char* — populate_service_map copies from PROGMEM at play() time.
+  template<typename V> void add_data(const __FlashStringHelper *key, V &&value) {
+    this->add_kv_(this->data_, reinterpret_cast<const char *>(key), std::forward<V>(value));
+  }
+  template<typename V> void add_data_template(const __FlashStringHelper *key, V &&value) {
+    this->add_kv_(this->data_template_, reinterpret_cast<const char *>(key), std::forward<V>(value));
+  }
+  template<typename V> void add_variable(const __FlashStringHelper *key, V &&value) {
+    this->add_kv_(this->variables_, reinterpret_cast<const char *>(key), std::forward<V>(value));
+  }
+#endif
+
 #ifdef USE_API_HOMEASSISTANT_ACTION_RESPONSES
   template<typename T> void set_response_template(T response_template) {
     this->response_template_ = response_template;
@@ -217,7 +233,32 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
                                    Ts... x) {
     dest.init(source.size());
 
-    // Count non-static strings to allocate exact storage needed
+#ifdef USE_ESP8266
+    // On ESP8266, all static strings from codegen are FLASH_STRING (PROGMEM),
+    // so is_static_string() is always false — the zero-copy STATIC_STRING fast
+    // path from the non-ESP8266 branch cannot trigger. We copy all keys and
+    // values unconditionally: keys via _P functions (may be in PROGMEM), values
+    // via value() which handles FLASH_STRING internally.
+    value_storage.init(source.size() * 2);
+
+    for (auto &it : source) {
+      auto &kv = dest.emplace_back();
+
+      // Key: copy from possible PROGMEM
+      {
+        size_t key_len = strlen_P(it.key);
+        value_storage.push_back(std::string(key_len, '\0'));
+        memcpy_P(value_storage.back().data(), it.key, key_len);
+        kv.key = StringRef(value_storage.back());
+      }
+
+      // Value: value() handles FLASH_STRING via _P functions internally
+      value_storage.push_back(it.value.value(x...));
+      kv.value = StringRef(value_storage.back());
+    }
+#else
+    // On non-ESP8266, strings are directly readable from flash-mapped memory.
+    // Count non-static strings to allocate exact storage needed.
     size_t lambda_count = 0;
     for (const auto &it : source) {
       if (!it.value.is_static_string()) {
@@ -231,14 +272,15 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
       kv.key = StringRef(it.key);
 
       if (it.value.is_static_string()) {
-        // Static string from YAML - zero allocation
+        // Static string — pointer directly readable, zero allocation
         kv.value = StringRef(it.value.get_static_string());
       } else {
-        // Lambda evaluation - store result, reference it
+        // Lambda — evaluate and store result
         value_storage.push_back(it.value.value(x...));
         kv.value = StringRef(value_storage.back());
       }
     }
+#endif
   }
 
   APIServer *parent_;

esphome/components/cse7766/cse7766.cpp

@@ -7,7 +7,6 @@ namespace esphome {
 namespace cse7766 {
 
 static const char *const TAG = "cse7766";
-static constexpr size_t CSE7766_RAW_DATA_SIZE = 24;
 
 void CSE7766Component::loop() {
   const uint32_t now = App.get_loop_component_start_time();
@@ -16,25 +15,39 @@ void CSE7766Component::loop() {
     this->raw_data_index_ = 0;
   }
 
-  if (this->available() == 0) {
+  // Early return prevents updating last_transmission_ when no data is available.
+  int avail = this->available();
+  if (avail <= 0) {
     return;
   }
 
   this->last_transmission_ = now;
-  while (this->available() != 0) {
-    this->read_byte(&this->raw_data_[this->raw_data_index_]);
-    if (!this->check_byte_()) {
-      this->raw_data_index_ = 0;
-      this->status_set_warning();
-      continue;
-    }
 
-    if (this->raw_data_index_ == 23) {
-      this->parse_data_();
-      this->status_clear_warning();
+  // Read all available bytes in batches to reduce UART call overhead.
+  // At 4800 baud (~480 bytes/sec) with ~122 Hz loop rate, typically ~4 bytes per call.
+  uint8_t buf[CSE7766_RAW_DATA_SIZE];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
     }
+    avail -= to_read;
 
-    this->raw_data_index_ = (this->raw_data_index_ + 1) % 24;
+    for (size_t i = 0; i < to_read; i++) {
+      this->raw_data_[this->raw_data_index_] = buf[i];
+      if (!this->check_byte_()) {
+        this->raw_data_index_ = 0;
+        this->status_set_warning();
+        continue;
+      }
+
+      if (this->raw_data_index_ == CSE7766_RAW_DATA_SIZE - 1) {
+        this->parse_data_();
+        this->status_clear_warning();
+      }
+
+      this->raw_data_index_ = (this->raw_data_index_ + 1) % CSE7766_RAW_DATA_SIZE;
+    }
   }
 }
 
@@ -53,14 +66,15 @@ bool CSE7766Component::check_byte_() {
     return true;
   }
 
-  if (index == 23) {
+  if (index == CSE7766_RAW_DATA_SIZE - 1) {
     uint8_t checksum = 0;
-    for (uint8_t i = 2; i < 23; i++) {
+    for (uint8_t i = 2; i < CSE7766_RAW_DATA_SIZE - 1; i++) {
       checksum += this->raw_data_[i];
     }
 
-    if (checksum != this->raw_data_[23]) {
-      ESP_LOGW(TAG, "Invalid checksum from CSE7766: 0x%02X != 0x%02X", checksum, this->raw_data_[23]);
+    if (checksum != this->raw_data_[CSE7766_RAW_DATA_SIZE - 1]) {
+      ESP_LOGW(TAG, "Invalid checksum from CSE7766: 0x%02X != 0x%02X", checksum,
+               this->raw_data_[CSE7766_RAW_DATA_SIZE - 1]);
       return false;
     }
     return true;

esphome/components/cse7766/cse7766.h

@@ -8,6 +8,8 @@
 namespace esphome {
 namespace cse7766 {
 
+static constexpr size_t CSE7766_RAW_DATA_SIZE = 24;
+
 class CSE7766Component : public Component, public uart::UARTDevice {
  public:
   void set_voltage_sensor(sensor::Sensor *voltage_sensor) { voltage_sensor_ = voltage_sensor; }
@@ -33,7 +35,7 @@ class CSE7766Component : public Component, public uart::UARTDevice {
                          this->raw_data_[start_index + 2]);
   }
 
-  uint8_t raw_data_[24];
+  uint8_t raw_data_[CSE7766_RAW_DATA_SIZE];
   uint8_t raw_data_index_{0};
   uint32_t last_transmission_{0};
   sensor::Sensor *voltage_sensor_{nullptr};

esphome/components/dfplayer/dfplayer.cpp

@@ -1,4 +1,5 @@
 #include "dfplayer.h"
+#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
 namespace esphome {
@@ -131,140 +132,149 @@ void DFPlayer::send_cmd_(uint8_t cmd, uint16_t argument) {
 }
 
 void DFPlayer::loop() {
-  // Read message
-  while (this->available()) {
-    uint8_t byte;
-    this->read_byte(&byte);
-
-    if (this->read_pos_ == DFPLAYER_READ_BUFFER_LENGTH)
-      this->read_pos_ = 0;
-
-    switch (this->read_pos_) {
-      case 0:  // Start mark
-        if (byte != 0x7E)
-          continue;
-        break;
-      case 1:  // Version
-        if (byte != 0xFF) {
-          ESP_LOGW(TAG, "Expected Version 0xFF, got %#02x", byte);
-          this->read_pos_ = 0;
-          continue;
-        }
-        break;
-      case 2:  // Buffer length
-        if (byte != 0x06) {
-          ESP_LOGW(TAG, "Expected Buffer length 0x06, got %#02x", byte);
-          this->read_pos_ = 0;
-          continue;
-        }
-        break;
-      case 9:  // End byte
-#ifdef ESPHOME_LOG_HAS_VERY_VERBOSE
-        char byte_sequence[100];
-        byte_sequence[0] = '\0';
-        for (size_t i = 0; i < this->read_pos_ + 1; ++i) {
-          snprintf(byte_sequence + strlen(byte_sequence), sizeof(byte_sequence) - strlen(byte_sequence), "%02X ",
-                   this->read_buffer_[i]);
-        }
-        ESP_LOGVV(TAG, "Received byte sequence: %s", byte_sequence);
-#endif
-        if (byte != 0xEF) {
-          ESP_LOGW(TAG, "Expected end byte 0xEF, got %#02x", byte);
-          this->read_pos_ = 0;
-          continue;
-        }
-        // Parse valid received command
-        uint8_t cmd = this->read_buffer_[3];
-        uint16_t argument = (this->read_buffer_[5] << 8) | this->read_buffer_[6];
-
-        ESP_LOGV(TAG, "Received message cmd: %#02x arg %#04x", cmd, argument);
-
-        switch (cmd) {
-          case 0x3A:
-            if (argument == 1) {
-              ESP_LOGI(TAG, "USB loaded");
-            } else if (argument == 2) {
-              ESP_LOGI(TAG, "TF Card loaded");
-            }
-            break;
-          case 0x3B:
-            if (argument == 1) {
-              ESP_LOGI(TAG, "USB unloaded");
-            } else if (argument == 2) {
-              ESP_LOGI(TAG, "TF Card unloaded");
-            }
-            break;
-          case 0x3F:
-            if (argument == 1) {
-              ESP_LOGI(TAG, "USB available");
-            } else if (argument == 2) {
-              ESP_LOGI(TAG, "TF Card available");
-            } else if (argument == 3) {
-              ESP_LOGI(TAG, "USB, TF Card available");
-            }
-            break;
-          case 0x40:
-            ESP_LOGV(TAG, "Nack");
-            this->ack_set_is_playing_ = false;
-            this->ack_reset_is_playing_ = false;
-            switch (argument) {
-              case 0x01:
-                ESP_LOGE(TAG, "Module is busy or uninitialized");
-                break;
-              case 0x02:
-                ESP_LOGE(TAG, "Module is in sleep mode");
-                break;
-              case 0x03:
-                ESP_LOGE(TAG, "Serial receive error");
-                break;
-              case 0x04:
-                ESP_LOGE(TAG, "Checksum incorrect");
-                break;
-              case 0x05:
-                ESP_LOGE(TAG, "Specified track is out of current track scope");
-                this->is_playing_ = false;
-                break;
-              case 0x06:
-                ESP_LOGE(TAG, "Specified track is not found");
-                this->is_playing_ = false;
-                break;
-              case 0x07:
-                ESP_LOGE(TAG, "Insertion error (an inserting operation only can be done when a track is being played)");
-                break;
-              case 0x08:
-                ESP_LOGE(TAG, "SD card reading failed (SD card pulled out or damaged)");
-                break;
-              case 0x09:
-                ESP_LOGE(TAG, "Entered into sleep mode");
-                this->is_playing_ = false;
-                break;
-            }
-            break;
-          case 0x41:
-            ESP_LOGV(TAG, "Ack ok");
-            this->is_playing_ |= this->ack_set_is_playing_;
-            this->is_playing_ &= !this->ack_reset_is_playing_;
-            this->ack_set_is_playing_ = false;
-            this->ack_reset_is_playing_ = false;
-            break;
-          case 0x3C:
-            ESP_LOGV(TAG, "Playback finished (USB drive)");
-            this->is_playing_ = false;
-            this->on_finished_playback_callback_.call();
-          case 0x3D:
-            ESP_LOGV(TAG, "Playback finished (SD card)");
-            this->is_playing_ = false;
-            this->on_finished_playback_callback_.call();
-            break;
-          default:
-            ESP_LOGE(TAG, "Received unknown cmd %#02x arg %#04x", cmd, argument);
-        }
-        this->sent_cmd_ = 0;
-        this->read_pos_ = 0;
-        continue;
+  // Read all available bytes in batches to reduce UART call overhead.
+  int avail = this->available();
+  uint8_t buf[64];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
+    for (size_t bi = 0; bi < to_read; bi++) {
+      uint8_t byte = buf[bi];
+
+      if (this->read_pos_ == DFPLAYER_READ_BUFFER_LENGTH)
+        this->read_pos_ = 0;
+
+      switch (this->read_pos_) {
+        case 0:  // Start mark
+          if (byte != 0x7E)
+            continue;
+          break;
+        case 1:  // Version
+          if (byte != 0xFF) {
+            ESP_LOGW(TAG, "Expected Version 0xFF, got %#02x", byte);
+            this->read_pos_ = 0;
+            continue;
+          }
+          break;
+        case 2:  // Buffer length
+          if (byte != 0x06) {
+            ESP_LOGW(TAG, "Expected Buffer length 0x06, got %#02x", byte);
+            this->read_pos_ = 0;
+            continue;
+          }
+          break;
+        case 9:  // End byte
+#ifdef ESPHOME_LOG_HAS_VERY_VERBOSE
+          char byte_sequence[100];
+          byte_sequence[0] = '\0';
+          for (size_t i = 0; i < this->read_pos_ + 1; ++i) {
+            snprintf(byte_sequence + strlen(byte_sequence), sizeof(byte_sequence) - strlen(byte_sequence), "%02X ",
+                     this->read_buffer_[i]);
+          }
+          ESP_LOGVV(TAG, "Received byte sequence: %s", byte_sequence);
+#endif
+          if (byte != 0xEF) {
+            ESP_LOGW(TAG, "Expected end byte 0xEF, got %#02x", byte);
+            this->read_pos_ = 0;
+            continue;
+          }
+          // Parse valid received command
+          uint8_t cmd = this->read_buffer_[3];
+          uint16_t argument = (this->read_buffer_[5] << 8) | this->read_buffer_[6];
+
+          ESP_LOGV(TAG, "Received message cmd: %#02x arg %#04x", cmd, argument);
+
+          switch (cmd) {
+            case 0x3A:
+              if (argument == 1) {
+                ESP_LOGI(TAG, "USB loaded");
+              } else if (argument == 2) {
+                ESP_LOGI(TAG, "TF Card loaded");
+              }
+              break;
+            case 0x3B:
+              if (argument == 1) {
+                ESP_LOGI(TAG, "USB unloaded");
+              } else if (argument == 2) {
+                ESP_LOGI(TAG, "TF Card unloaded");
+              }
+              break;
+            case 0x3F:
+              if (argument == 1) {
+                ESP_LOGI(TAG, "USB available");
+              } else if (argument == 2) {
+                ESP_LOGI(TAG, "TF Card available");
+              } else if (argument == 3) {
+                ESP_LOGI(TAG, "USB, TF Card available");
+              }
+              break;
+            case 0x40:
+              ESP_LOGV(TAG, "Nack");
+              this->ack_set_is_playing_ = false;
+              this->ack_reset_is_playing_ = false;
+              switch (argument) {
+                case 0x01:
+                  ESP_LOGE(TAG, "Module is busy or uninitialized");
+                  break;
+                case 0x02:
+                  ESP_LOGE(TAG, "Module is in sleep mode");
+                  break;
+                case 0x03:
+                  ESP_LOGE(TAG, "Serial receive error");
+                  break;
+                case 0x04:
+                  ESP_LOGE(TAG, "Checksum incorrect");
+                  break;
+                case 0x05:
+                  ESP_LOGE(TAG, "Specified track is out of current track scope");
+                  this->is_playing_ = false;
+                  break;
+                case 0x06:
+                  ESP_LOGE(TAG, "Specified track is not found");
+                  this->is_playing_ = false;
+                  break;
+                case 0x07:
+                  ESP_LOGE(TAG,
+                           "Insertion error (an inserting operation only can be done when a track is being played)");
+                  break;
+                case 0x08:
+                  ESP_LOGE(TAG, "SD card reading failed (SD card pulled out or damaged)");
+                  break;
+                case 0x09:
+                  ESP_LOGE(TAG, "Entered into sleep mode");
+                  this->is_playing_ = false;
+                  break;
+              }
+              break;
+            case 0x41:
+              ESP_LOGV(TAG, "Ack ok");
+              this->is_playing_ |= this->ack_set_is_playing_;
+              this->is_playing_ &= !this->ack_reset_is_playing_;
+              this->ack_set_is_playing_ = false;
+              this->ack_reset_is_playing_ = false;
+              break;
+            case 0x3C:
+              ESP_LOGV(TAG, "Playback finished (USB drive)");
+              this->is_playing_ = false;
+              this->on_finished_playback_callback_.call();
+            case 0x3D:
+              ESP_LOGV(TAG, "Playback finished (SD card)");
+              this->is_playing_ = false;
+              this->on_finished_playback_callback_.call();
+              break;
+            default:
+              ESP_LOGE(TAG, "Received unknown cmd %#02x arg %#04x", cmd, argument);
+          }
+          this->sent_cmd_ = 0;
+          this->read_pos_ = 0;
+          continue;
+      }
+      this->read_buffer_[this->read_pos_] = byte;
+      this->read_pos_++;
     }
-    this->read_buffer_[this->read_pos_] = byte;
-    this->read_pos_++;
   }
 }
 void DFPlayer::dump_config() {

esphome/components/esp32/__init__.py

@@ -1435,6 +1435,10 @@ async def to_code(config):
         CORE.relative_internal_path(".espressif")
     )
 
+    # Set the uv cache inside the data dir so "Clean All" clears it.
+    # Avoids persistent corrupted cache from mid-stream download failures.
+    os.environ["UV_CACHE_DIR"] = str(CORE.relative_internal_path(".uv_cache"))
+
     if conf[CONF_TYPE] == FRAMEWORK_ESP_IDF:
         cg.add_build_flag("-DUSE_ESP_IDF")
         cg.add_build_flag("-DUSE_ESP32_FRAMEWORK_ESP_IDF")

esphome/components/esp32_ble/ble_uuid.h

@@ -48,7 +48,7 @@ class ESPBTUUID {
 
   // Remove before 2026.8.0
   ESPDEPRECATED("Use to_str() instead. Removed in 2026.8.0", "2026.2.0")
-  std::string to_string() const;
+  std::string to_string() const;  // NOLINT
   const char *to_str(std::span<char, UUID_STR_LEN> output) const;
 
  protected:

esphome/components/i2c/i2c_bus_arduino.cpp

@@ -134,25 +134,23 @@ ErrorCode ArduinoI2CBus::write_readv(uint8_t address, const uint8_t *write_buffe
     for (size_t j = 0; j != read_count; j++)
       read_buffer[j] = wire_->read();
   }
-  switch (status) {
-    case 0:
-      return ERROR_OK;
-    case 1:
-      // transmit buffer not large enough
-      ESP_LOGVV(TAG, "TX failed: buffer not large enough");
-      return ERROR_UNKNOWN;
-    case 2:
-    case 3:
-      ESP_LOGVV(TAG, "TX failed: not acknowledged: %d", status);
-      return ERROR_NOT_ACKNOWLEDGED;
-    case 5:
-      ESP_LOGVV(TAG, "TX failed: timeout");
-      return ERROR_UNKNOWN;
-    case 4:
-    default:
-      ESP_LOGVV(TAG, "TX failed: unknown error %u", status);
-      return ERROR_UNKNOWN;
+  // Avoid switch to prevent compiler-generated lookup table in RAM on ESP8266
+  if (status == 0)
+    return ERROR_OK;
+  if (status == 1) {
+    ESP_LOGVV(TAG, "TX failed: buffer not large enough");
+    return ERROR_UNKNOWN;
   }
+  if (status == 2 || status == 3) {
+    ESP_LOGVV(TAG, "TX failed: not acknowledged: %u", status);
+    return ERROR_NOT_ACKNOWLEDGED;
+  }
+  if (status == 5) {
+    ESP_LOGVV(TAG, "TX failed: timeout");
+    return ERROR_UNKNOWN;
+  }
+  ESP_LOGVV(TAG, "TX failed: unknown error %u", status);
+  return ERROR_UNKNOWN;
 }
 
 /// Perform I2C bus recovery, see:

esphome/components/ld2410/ld2410.cpp

@@ -275,8 +275,19 @@ void LD2410Component::restart_and_read_all_info() {
 }
 
 void LD2410Component::loop() {
-  while (this->available()) {
-    this->readline_(this->read());
+  // Read all available bytes in batches to reduce UART call overhead.
+  int avail = this->available();
+  uint8_t buf[MAX_LINE_LENGTH];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
+
+    for (size_t i = 0; i < to_read; i++) {
+      this->readline_(buf[i]);
+    }
   }
 }
 

esphome/components/ld2412/ld2412.cpp

@@ -310,8 +310,19 @@ void LD2412Component::restart_and_read_all_info() {
 }
 
 void LD2412Component::loop() {
-  while (this->available()) {
-    this->readline_(this->read());
+  // Read all available bytes in batches to reduce UART call overhead.
+  int avail = this->available();
+  uint8_t buf[MAX_LINE_LENGTH];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
+
+    for (size_t i = 0; i < to_read; i++) {
+      this->readline_(buf[i]);
+    }
   }
 }
 

esphome/components/ld2450/ld2450.cpp

@@ -276,8 +276,19 @@ void LD2450Component::dump_config() {
 }
 
 void LD2450Component::loop() {
-  while (this->available()) {
-    this->readline_(this->read());
+  // Read all available bytes in batches to reduce UART call overhead.
+  int avail = this->available();
+  uint8_t buf[MAX_LINE_LENGTH];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
+
+    for (size_t i = 0; i < to_read; i++) {
+      this->readline_(buf[i]);
+    }
   }
 }
 

esphome/components/modbus/modbus.cpp

@@ -19,16 +19,25 @@ void Modbus::setup() {
 void Modbus::loop() {
   const uint32_t now = App.get_loop_component_start_time();
 
-  while (this->available()) {
-    uint8_t byte;
-    this->read_byte(&byte);
-    if (this->parse_modbus_byte_(byte)) {
-      this->last_modbus_byte_ = now;
-    } else {
-      size_t at = this->rx_buffer_.size();
-      if (at > 0) {
-        ESP_LOGV(TAG, "Clearing buffer of %d bytes - parse failed", at);
-        this->rx_buffer_.clear();
+  // Read all available bytes in batches to reduce UART call overhead.
+  int avail = this->available();
+  uint8_t buf[64];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
+
+    for (size_t i = 0; i < to_read; i++) {
+      if (this->parse_modbus_byte_(buf[i])) {
+        this->last_modbus_byte_ = now;
+      } else {
+        size_t at = this->rx_buffer_.size();
+        if (at > 0) {
+          ESP_LOGV(TAG, "Clearing buffer of %d bytes - parse failed", at);
+          this->rx_buffer_.clear();
+        }
       }
     }
   }
@@ -219,39 +228,50 @@ void Modbus::send(uint8_t address, uint8_t function_code, uint16_t start_address
     return;
   }
 
-  std::vector<uint8_t> data;
-  data.push_back(address);
-  data.push_back(function_code);
+  static constexpr size_t ADDR_SIZE = 1;
+  static constexpr size_t FC_SIZE = 1;
+  static constexpr size_t START_ADDR_SIZE = 2;
+  static constexpr size_t NUM_ENTITIES_SIZE = 2;
+  static constexpr size_t BYTE_COUNT_SIZE = 1;
+  static constexpr size_t MAX_PAYLOAD_SIZE = std::numeric_limits<uint8_t>::max();
+  static constexpr size_t CRC_SIZE = 2;
+  static constexpr size_t MAX_FRAME_SIZE =
+      ADDR_SIZE + FC_SIZE + START_ADDR_SIZE + NUM_ENTITIES_SIZE + BYTE_COUNT_SIZE + MAX_PAYLOAD_SIZE + CRC_SIZE;
+  uint8_t data[MAX_FRAME_SIZE];
+  size_t pos = 0;
+
+  data[pos++] = address;
+  data[pos++] = function_code;
   if (this->role == ModbusRole::CLIENT) {
-    data.push_back(start_address >> 8);
-    data.push_back(start_address >> 0);
+    data[pos++] = start_address >> 8;
+    data[pos++] = start_address >> 0;
     if (function_code != ModbusFunctionCode::WRITE_SINGLE_COIL &&
         function_code != ModbusFunctionCode::WRITE_SINGLE_REGISTER) {
-      data.push_back(number_of_entities >> 8);
-      data.push_back(number_of_entities >> 0);
+      data[pos++] = number_of_entities >> 8;
+      data[pos++] = number_of_entities >> 0;
     }
   }
 
   if (payload != nullptr) {
     if (this->role == ModbusRole::SERVER || function_code == ModbusFunctionCode::WRITE_MULTIPLE_COILS ||
         function_code == ModbusFunctionCode::WRITE_MULTIPLE_REGISTERS) {  // Write multiple
-      data.push_back(payload_len);                                        // Byte count is required for write
+      data[pos++] = payload_len;                                          // Byte count is required for write
     } else {
       payload_len = 2;  // Write single register or coil
     }
     for (int i = 0; i < payload_len; i++) {
-      data.push_back(payload[i]);
+      data[pos++] = payload[i];
     }
   }
 
-  auto crc = crc16(data.data(), data.size());
-  data.push_back(crc >> 0);
-  data.push_back(crc >> 8);
+  auto crc = crc16(data, pos);
+  data[pos++] = crc >> 0;
+  data[pos++] = crc >> 8;
 
   if (this->flow_control_pin_ != nullptr)
     this->flow_control_pin_->digital_write(true);
 
-  this->write_array(data);
+  this->write_array(data, pos);
   this->flush();
 
   if (this->flow_control_pin_ != nullptr)
@@ -261,7 +281,7 @@ void Modbus::send(uint8_t address, uint8_t function_code, uint16_t start_address
 #if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
   char hex_buf[format_hex_pretty_size(MODBUS_MAX_LOG_BYTES)];
 #endif
-  ESP_LOGV(TAG, "Modbus write: %s", format_hex_pretty_to(hex_buf, data.data(), data.size()));
+  ESP_LOGV(TAG, "Modbus write: %s", format_hex_pretty_to(hex_buf, data, pos));
 }
 
 // Helper function for lambdas

esphome/components/nextion/nextion.cpp

@@ -397,11 +397,17 @@ bool Nextion::remove_from_q_(bool report_empty) {
 }
 
 void Nextion::process_serial_() {
-  uint8_t d;
+  // Read all available bytes in batches to reduce UART call overhead.
+  int avail = this->available();
+  uint8_t buf[64];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
 
-  while (this->available()) {
-    read_byte(&d);
-    this->command_data_ += d;
+    this->command_data_.append(reinterpret_cast<const char *>(buf), to_read);
   }
 }
 // nextion.tech/instruction-set/

esphome/components/pipsolar/pipsolar.cpp

@@ -13,9 +13,12 @@ void Pipsolar::setup() {
 }
 
 void Pipsolar::empty_uart_buffer_() {
-  uint8_t byte;
-  while (this->available()) {
-    this->read_byte(&byte);
+  uint8_t buf[64];
+  int avail;
+  while ((avail = this->available()) > 0) {
+    if (!this->read_array(buf, std::min(static_cast<size_t>(avail), sizeof(buf)))) {
+      break;
+    }
   }
 }
 
@@ -94,32 +97,47 @@ void Pipsolar::loop() {
   }
 
   if (this->state_ == STATE_COMMAND || this->state_ == STATE_POLL) {
-    while (this->available()) {
-      uint8_t byte;
-      this->read_byte(&byte);
-
-      // make sure data and null terminator fit in buffer
-      if (this->read_pos_ >= PIPSOLAR_READ_BUFFER_LENGTH - 1) {
-        this->read_pos_ = 0;
-        this->empty_uart_buffer_();
-        ESP_LOGW(TAG, "response data too long, discarding.");
+    int avail = this->available();
+    while (avail > 0) {
+      uint8_t buf[64];
+      size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+      if (!this->read_array(buf, to_read)) {
         break;
       }
-      this->read_buffer_[this->read_pos_] = byte;
-      this->read_pos_++;
+      avail -= to_read;
+      bool done = false;
+      for (size_t i = 0; i < to_read; i++) {
+        uint8_t byte = buf[i];
 
-      // end of answer
-      if (byte == 0x0D) {
-        this->read_buffer_[this->read_pos_] = 0;
-        this->empty_uart_buffer_();
-        if (this->state_ == STATE_POLL) {
-          this->state_ = STATE_POLL_COMPLETE;
+        // make sure data and null terminator fit in buffer
+        if (this->read_pos_ >= PIPSOLAR_READ_BUFFER_LENGTH - 1) {
+          this->read_pos_ = 0;
+          this->empty_uart_buffer_();
+          ESP_LOGW(TAG, "response data too long, discarding.");
+          done = true;
+          break;
         }
-        if (this->state_ == STATE_COMMAND) {
-          this->state_ = STATE_COMMAND_COMPLETE;
+        this->read_buffer_[this->read_pos_] = byte;
+        this->read_pos_++;
+
+        // end of answer
+        if (byte == 0x0D) {
+          this->read_buffer_[this->read_pos_] = 0;
+          this->empty_uart_buffer_();
+          if (this->state_ == STATE_POLL) {
+            this->state_ = STATE_POLL_COMPLETE;
+          }
+          if (this->state_ == STATE_COMMAND) {
+            this->state_ = STATE_COMMAND_COMPLETE;
+          }
+          done = true;
+          break;
         }
       }
-    }  // available
+      if (done) {
+        break;
+      }
+    }
   }
   if (this->state_ == STATE_COMMAND) {
     if (millis() - this->command_start_millis_ > esphome::pipsolar::Pipsolar::COMMAND_TIMEOUT) {

esphome/components/rd03d/rd03d.cpp

@@ -1,4 +1,5 @@
 #include "rd03d.h"
+#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 #include <cmath>
 
@@ -80,37 +81,47 @@ void RD03DComponent::dump_config() {
 }
 
 void RD03DComponent::loop() {
-  while (this->available()) {
-    uint8_t byte = this->read();
-    ESP_LOGVV(TAG, "Received byte: 0x%02X, buffer_pos: %d", byte, this->buffer_pos_);
+  // Read all available bytes in batches to reduce UART call overhead.
+  int avail = this->available();
+  uint8_t buf[64];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
+    for (size_t i = 0; i < to_read; i++) {
+      uint8_t byte = buf[i];
+      ESP_LOGVV(TAG, "Received byte: 0x%02X, buffer_pos: %d", byte, this->buffer_pos_);
 
-    // Check if we're looking for frame header
-    if (this->buffer_pos_ < FRAME_HEADER_SIZE) {
-      if (byte == FRAME_HEADER[this->buffer_pos_]) {
-        this->buffer_[this->buffer_pos_++] = byte;
-      } else if (byte == FRAME_HEADER[0]) {
-        // Start over if we see a potential new header
-        this->buffer_[0] = byte;
-        this->buffer_pos_ = 1;
-      } else {
+      // Check if we're looking for frame header
+      if (this->buffer_pos_ < FRAME_HEADER_SIZE) {
+        if (byte == FRAME_HEADER[this->buffer_pos_]) {
+          this->buffer_[this->buffer_pos_++] = byte;
+        } else if (byte == FRAME_HEADER[0]) {
+          // Start over if we see a potential new header
+          this->buffer_[0] = byte;
+          this->buffer_pos_ = 1;
+        } else {
+          this->buffer_pos_ = 0;
+        }
+        continue;
+      }
+
+      // Accumulate data bytes
+      this->buffer_[this->buffer_pos_++] = byte;
+
+      // Check if we have a complete frame
+      if (this->buffer_pos_ == FRAME_SIZE) {
+        // Validate footer
+        if (this->buffer_[FRAME_SIZE - 2] == FRAME_FOOTER[0] && this->buffer_[FRAME_SIZE - 1] == FRAME_FOOTER[1]) {
+          this->process_frame_();
+        } else {
+          ESP_LOGW(TAG, "Invalid frame footer: 0x%02X 0x%02X (expected 0x55 0xCC)", this->buffer_[FRAME_SIZE - 2],
+                   this->buffer_[FRAME_SIZE - 1]);
+        }
         this->buffer_pos_ = 0;
       }
-      continue;
-    }
-
-    // Accumulate data bytes
-    this->buffer_[this->buffer_pos_++] = byte;
-
-    // Check if we have a complete frame
-    if (this->buffer_pos_ == FRAME_SIZE) {
-      // Validate footer
-      if (this->buffer_[FRAME_SIZE - 2] == FRAME_FOOTER[0] && this->buffer_[FRAME_SIZE - 1] == FRAME_FOOTER[1]) {
-        this->process_frame_();
-      } else {
-        ESP_LOGW(TAG, "Invalid frame footer: 0x%02X 0x%02X (expected 0x55 0xCC)", this->buffer_[FRAME_SIZE - 2],
-                 this->buffer_[FRAME_SIZE - 1]);
-      }
-      this->buffer_pos_ = 0;
     }
   }
 }

esphome/components/rf_bridge/rf_bridge.cpp

@@ -136,14 +136,21 @@ void RFBridgeComponent::loop() {
     this->last_bridge_byte_ = now;
   }
 
-  while (this->available()) {
-    uint8_t byte;
-    this->read_byte(&byte);
-    if (this->parse_bridge_byte_(byte)) {
-      ESP_LOGVV(TAG, "Parsed: 0x%02X", byte);
-      this->last_bridge_byte_ = now;
-    } else {
-      this->rx_buffer_.clear();
+  int avail = this->available();
+  while (avail > 0) {
+    uint8_t buf[64];
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
+    for (size_t i = 0; i < to_read; i++) {
+      if (this->parse_bridge_byte_(buf[i])) {
+        ESP_LOGVV(TAG, "Parsed: 0x%02X", buf[i]);
+        this->last_bridge_byte_ = now;
+      } else {
+        this->rx_buffer_.clear();
+      }
     }
   }
 }

esphome/components/seeed_mr24hpc1/seeed_mr24hpc1.cpp

@@ -106,12 +106,19 @@ void MR24HPC1Component::update_() {
 
 // main loop
 void MR24HPC1Component::loop() {
-  uint8_t byte;
+  // Read all available bytes in batches to reduce UART call overhead.
+  int avail = this->available();
+  uint8_t buf[64];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
 
-  // Is there data on the serial port
-  while (this->available()) {
-    this->read_byte(&byte);
-    this->r24_split_data_frame_(byte);  // split data frame
+    for (size_t i = 0; i < to_read; i++) {
+      this->r24_split_data_frame_(buf[i]);  // split data frame
+    }
   }
 
   if ((this->s_output_info_switch_flag_ == OUTPUT_SWTICH_OFF) &&

esphome/components/seeed_mr60bha2/seeed_mr60bha2.cpp

@@ -30,14 +30,21 @@ void MR60BHA2Component::dump_config() {
 
 // main loop
 void MR60BHA2Component::loop() {
-  uint8_t byte;
+  // Read all available bytes in batches to reduce UART call overhead.
+  int avail = this->available();
+  uint8_t buf[64];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
 
-  // Is there data on the serial port
-  while (this->available()) {
-    this->read_byte(&byte);
-    this->rx_message_.push_back(byte);
-    if (!this->validate_message_()) {
-      this->rx_message_.clear();
+    for (size_t i = 0; i < to_read; i++) {
+      this->rx_message_.push_back(buf[i]);
+      if (!this->validate_message_()) {
+        this->rx_message_.clear();
+      }
     }
   }
 }

esphome/components/seeed_mr60fda2/seeed_mr60fda2.cpp

@@ -49,12 +49,19 @@ void MR60FDA2Component::setup() {
 
 // main loop
 void MR60FDA2Component::loop() {
-  uint8_t byte;
+  // Read all available bytes in batches to reduce UART call overhead.
+  int avail = this->available();
+  uint8_t buf[64];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
 
-  // Is there data on the serial port
-  while (this->available()) {
-    this->read_byte(&byte);
-    this->split_frame_(byte);  // split data frame
+    for (size_t i = 0; i < to_read; i++) {
+      this->split_frame_(buf[i]);  // split data frame
+    }
   }
 }
 

esphome/components/tuya/tuya.cpp

@@ -31,10 +31,19 @@ void Tuya::setup() {
 }
 
 void Tuya::loop() {
-  while (this->available()) {
-    uint8_t c;
-    this->read_byte(&c);
-    this->handle_char_(c);
+  // Read all available bytes in batches to reduce UART call overhead.
+  int avail = this->available();
+  uint8_t buf[64];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
+
+    for (size_t i = 0; i < to_read; i++) {
+      this->handle_char_(buf[i]);
+    }
   }
   process_command_queue_();
 }

esphome/components/voice_assistant/voice_assistant.h

@@ -83,7 +83,7 @@ struct Timer {
   }
   // Remove before 2026.8.0
   ESPDEPRECATED("Use to_str() instead. Removed in 2026.8.0", "2026.2.0")
-  std::string to_string() const {
+  std::string to_string() const {  // NOLINT
     char buffer[TO_STR_BUFFER_SIZE];
     return this->to_str(buffer);
   }

esphome/components/web_server_base/__init__.py

@@ -1,8 +1,11 @@
+from pathlib import Path
+
 import esphome.codegen as cg
 import esphome.config_validation as cv
 from esphome.const import CONF_ID
 from esphome.core import CORE, coroutine_with_priority
 from esphome.coroutine import CoroPriority
+from esphome.helpers import copy_file_if_changed
 
 CODEOWNERS = ["@esphome/core"]
 DEPENDENCIES = ["network"]
@@ -49,5 +52,15 @@ async def to_code(config):
             CORE.add_platformio_option(
                 "lib_ignore", ["ESPAsyncTCP", "AsyncTCP", "AsyncTCP_RP2040W"]
             )
+            # ESPAsyncWebServer uses Hash library for sha1() on RP2040
+            cg.add_library("Hash", None)
+            # Fix Hash.h include conflict: Crypto-no-arduino (used by dsmr)
+            # provides a Hash.h that shadows the framework's Hash library.
+            # Prepend the framework Hash path so it's found first.
+            copy_file_if_changed(
+                Path(__file__).parent / "fix_rp2040_hash.py.script",
+                CORE.relative_build_path("fix_rp2040_hash.py"),
+            )
+            cg.add_platformio_option("extra_scripts", ["pre:fix_rp2040_hash.py"])
         # https://github.com/ESP32Async/ESPAsyncWebServer/blob/main/library.json
         cg.add_library("ESP32Async/ESPAsyncWebServer", "3.9.6")

esphome/components/web_server_base/fix_rp2040_hash.py.script

@@ -0,0 +1,11 @@
+# ESPAsyncWebServer includes <Hash.h> expecting the Arduino-Pico framework's Hash
+# library (which provides sha1() functions). However, the Crypto-no-arduino library
+# (used by dsmr) also provides a Hash.h that can shadow the framework version when
+# PlatformIO's chain+ LDF mode auto-discovers it as a dependency.
+# Prepend the framework Hash path to CXXFLAGS so it is found first.
+import os
+
+Import("env")
+framework_dir = env.PioPlatform().get_package_dir("framework-arduinopico")
+hash_src = os.path.join(framework_dir, "libraries", "Hash", "src")
+env.Prepend(CXXFLAGS=["-I" + hash_src])

esphome/core/automation.h

@@ -4,6 +4,7 @@
 #include "esphome/core/defines.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/preferences.h"
+#include "esphome/core/progmem.h"
 #include "esphome/core/string_ref.h"
 #include <concepts>
 #include <functional>
@@ -56,6 +57,16 @@ template<typename T, typename... X> class TemplatableValue {
     this->static_str_ = str;
   }
 
+#ifdef USE_ESP8266
+  // On ESP8266, __FlashStringHelper* is a distinct type from const char*.
+  // ESPHOME_F(s) expands to F(s) which returns __FlashStringHelper* pointing to PROGMEM.
+  // Store as FLASH_STRING — value()/is_empty()/ref_or_copy_to() use _P functions
+  // to access the PROGMEM pointer safely.
+  TemplatableValue(const __FlashStringHelper *str) requires std::same_as<T, std::string> : type_(FLASH_STRING) {
+    this->static_str_ = reinterpret_cast<const char *>(str);
+  }
+#endif
+
   template<typename F> TemplatableValue(F value) requires(!std::invocable<F, X...>) : type_(VALUE) {
     if constexpr (USE_HEAP_STORAGE) {
       this->value_ = new T(std::move(value));
@@ -89,7 +100,7 @@ template<typename T, typename... X> class TemplatableValue {
       this->f_ = new std::function<T(X...)>(*other.f_);
     } else if (this->type_ == STATELESS_LAMBDA) {
       this->stateless_f_ = other.stateless_f_;
-    } else if (this->type_ == STATIC_STRING) {
+    } else if (this->type_ == STATIC_STRING || this->type_ == FLASH_STRING) {
       this->static_str_ = other.static_str_;
     }
   }
@@ -108,7 +119,7 @@ template<typename T, typename... X> class TemplatableValue {
       other.f_ = nullptr;
     } else if (this->type_ == STATELESS_LAMBDA) {
       this->stateless_f_ = other.stateless_f_;
-    } else if (this->type_ == STATIC_STRING) {
+    } else if (this->type_ == STATIC_STRING || this->type_ == FLASH_STRING) {
       this->static_str_ = other.static_str_;
     }
     other.type_ = NONE;
@@ -141,7 +152,7 @@ template<typename T, typename... X> class TemplatableValue {
     } else if (this->type_ == LAMBDA) {
       delete this->f_;
     }
-    // STATELESS_LAMBDA/STATIC_STRING/NONE: no cleanup needed (pointers, not heap-allocated)
+    // STATELESS_LAMBDA/STATIC_STRING/FLASH_STRING/NONE: no cleanup needed (pointers, not heap-allocated)
   }
 
   bool has_value() const { return this->type_ != NONE; }
@@ -165,6 +176,17 @@ template<typename T, typename... X> class TemplatableValue {
           return std::string(this->static_str_);
         }
         __builtin_unreachable();
+#ifdef USE_ESP8266
+      case FLASH_STRING:
+        // PROGMEM pointer — must use _P functions to access on ESP8266
+        if constexpr (std::same_as<T, std::string>) {
+          size_t len = strlen_P(this->static_str_);
+          std::string result(len, '\0');
+          memcpy_P(result.data(), this->static_str_, len);
+          return result;
+        }
+        __builtin_unreachable();
+#endif
       case NONE:
       default:
         return T{};
@@ -186,9 +208,12 @@ template<typename T, typename... X> class TemplatableValue {
   }
 
   /// Check if this holds a static string (const char* stored without allocation)
+  /// The pointer is always directly readable (RAM or flash-mapped).
+  /// Returns false for FLASH_STRING (PROGMEM on ESP8266, requires _P functions).
   bool is_static_string() const { return this->type_ == STATIC_STRING; }
 
   /// Get the static string pointer (only valid if is_static_string() returns true)
+  /// The pointer is always directly readable — FLASH_STRING uses a separate type.
   const char *get_static_string() const { return this->static_str_; }
 
   /// Check if the string value is empty without allocating (for std::string specialization).
@@ -200,6 +225,12 @@ template<typename T, typename... X> class TemplatableValue {
         return true;
       case STATIC_STRING:
         return this->static_str_ == nullptr || this->static_str_[0] == '\0';
+#ifdef USE_ESP8266
+      case FLASH_STRING:
+        // PROGMEM pointer — must use progmem_read_byte on ESP8266
+        return this->static_str_ == nullptr ||
+               progmem_read_byte(reinterpret_cast<const uint8_t *>(this->static_str_)) == '\0';
+#endif
       case VALUE:
         return this->value_->empty();
       default:  // LAMBDA/STATELESS_LAMBDA - must call value()
@@ -209,8 +240,9 @@ template<typename T, typename... X> class TemplatableValue {
 
   /// Get a StringRef to the string value without heap allocation when possible.
   /// For STATIC_STRING/VALUE, returns reference to existing data (no allocation).
+  /// For FLASH_STRING (ESP8266 PROGMEM), copies to provided buffer via _P functions.
   /// For LAMBDA/STATELESS_LAMBDA, calls value(), copies to provided buffer, returns ref to buffer.
-  /// @param lambda_buf Buffer used only for lambda case (must remain valid while StringRef is used).
+  /// @param lambda_buf Buffer used only for copy cases (must remain valid while StringRef is used).
   /// @param lambda_buf_size Size of the buffer.
   /// @return StringRef pointing to the string data.
   StringRef ref_or_copy_to(char *lambda_buf, size_t lambda_buf_size) const requires std::same_as<T, std::string> {
@@ -221,6 +253,19 @@ template<typename T, typename... X> class TemplatableValue {
         if (this->static_str_ == nullptr)
           return StringRef();
         return StringRef(this->static_str_, strlen(this->static_str_));
+#ifdef USE_ESP8266
+      case FLASH_STRING:
+        if (this->static_str_ == nullptr)
+          return StringRef();
+        {
+          // PROGMEM pointer — copy to buffer via _P functions
+          size_t len = strlen_P(this->static_str_);
+          size_t copy_len = std::min(len, lambda_buf_size - 1);
+          memcpy_P(lambda_buf, this->static_str_, copy_len);
+          lambda_buf[copy_len] = '\0';
+          return StringRef(lambda_buf, copy_len);
+        }
+#endif
       case VALUE:
         return StringRef(this->value_->data(), this->value_->size());
       default: {  // LAMBDA/STATELESS_LAMBDA - must call value() and copy
@@ -239,6 +284,7 @@ template<typename T, typename... X> class TemplatableValue {
    LAMBDA,
    STATELESS_LAMBDA,
    STATIC_STRING,  // For const char* when T is std::string - avoids heap allocation
+   FLASH_STRING,   // PROGMEM pointer on ESP8266; never set on other platforms
  } type_;
   // For std::string, use heap pointer to minimize union size (4 bytes vs 12+).
   // For other types, store value inline as before.
@@ -247,7 +293,7 @@ template<typename T, typename... X> class TemplatableValue {
     ValueStorage value_;  // T for inline storage, T* for heap storage
     std::function<T(X...)> *f_;
     T (*stateless_f_)(X...);
-    const char *static_str_;  // For STATIC_STRING type
+    const char *static_str_;  // For STATIC_STRING and FLASH_STRING types
   };
 };
 

esphome/core/component.cpp

@@ -152,7 +152,10 @@ void Component::set_retry(const std::string &name, uint32_t initial_wait_time, u
 
 void Component::set_retry(const char *name, uint32_t initial_wait_time, uint8_t max_attempts,
                           std::function<RetryResult(uint8_t)> &&f, float backoff_increase_factor) {  // NOLINT
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
   App.scheduler.set_retry(this, name, initial_wait_time, max_attempts, std::move(f), backoff_increase_factor);
+#pragma GCC diagnostic pop
 }
 
 bool Component::cancel_retry(const std::string &name) {  // NOLINT
@@ -163,7 +166,10 @@ bool Component::cancel_retry(const std::string &name) {  // NOLINT
 }
 
 bool Component::cancel_retry(const char *name) {  // NOLINT
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
   return App.scheduler.cancel_retry(this, name);
+#pragma GCC diagnostic pop
 }
 
 void Component::set_timeout(const std::string &name, uint32_t timeout, std::function<void()> &&f) {  // NOLINT
@@ -203,10 +209,18 @@ bool Component::cancel_interval(uint32_t id) { return App.scheduler.cancel_inter
 
 void Component::set_retry(uint32_t id, uint32_t initial_wait_time, uint8_t max_attempts,
                           std::function<RetryResult(uint8_t)> &&f, float backoff_increase_factor) {  // NOLINT
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
   App.scheduler.set_retry(this, id, initial_wait_time, max_attempts, std::move(f), backoff_increase_factor);
+#pragma GCC diagnostic pop
 }
 
-bool Component::cancel_retry(uint32_t id) { return App.scheduler.cancel_retry(this, id); }
+bool Component::cancel_retry(uint32_t id) {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+  return App.scheduler.cancel_retry(this, id);
+#pragma GCC diagnostic pop
+}
 
 void Component::call_loop() { this->loop(); }
 void Component::call_setup() { this->setup(); }
@@ -371,7 +385,10 @@ void Component::set_interval(uint32_t interval, std::function<void()> &&f) {  //
 }
 void Component::set_retry(uint32_t initial_wait_time, uint8_t max_attempts, std::function<RetryResult(uint8_t)> &&f,
                           float backoff_increase_factor) {  // NOLINT
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
   App.scheduler.set_retry(this, "", initial_wait_time, max_attempts, std::move(f), backoff_increase_factor);
+#pragma GCC diagnostic pop
 }
 bool Component::is_failed() const { return (this->component_state_ & COMPONENT_STATE_MASK) == COMPONENT_STATE_FAILED; }
 bool Component::is_ready() const {

esphome/core/component.h

@@ -68,6 +68,7 @@ extern const uint8_t STATUS_LED_OK;
 extern const uint8_t STATUS_LED_WARNING;
 extern const uint8_t STATUS_LED_ERROR;
 
+// Remove before 2026.8.0
 enum class RetryResult { DONE, RETRY };
 
 extern const uint16_t WARN_IF_BLOCKING_OVER_MS;
@@ -347,68 +348,40 @@ class Component {
   bool cancel_interval(const char *name);         // NOLINT
   bool cancel_interval(uint32_t id);              // NOLINT
 
-  /** Set an retry function with a unique name. Empty name means no cancelling possible.
-   *
-   * This will call the retry function f on the next scheduler loop. f should return RetryResult::DONE if
-   * it is successful and no repeat is required. Otherwise, returning RetryResult::RETRY will call f
-   * again in the future.
-   *
-   * The first retry of f happens after `initial_wait_time` milliseconds. The delay between retries is
-   * increased by multiplying by `backoff_increase_factor` each time. If no backoff_increase_factor is
-   * supplied (default = 1.0), the wait time will stay constant.
-   *
-   * The retry function f needs to accept a single argument: the number of attempts remaining. On the
-   * final retry of f, this value will be 0.
-   *
-   * This retry function can also be cancelled by name via cancel_retry().
-   *
-   * IMPORTANT: Do not rely on this having correct timing. This is only called from
-   * loop() and therefore can be significantly delayed.
-   *
-   * REMARK: It is an error to supply a negative or zero `backoff_increase_factor`, and 1.0 will be used instead.
-   *
-   * REMARK: The interval between retries is stored into a `uint32_t`, so this doesn't behave correctly
-   * if `initial_wait_time * (backoff_increase_factor ** (max_attempts - 2))` overflows.
-   *
-   * @param name The identifier for this retry function.
-   * @param initial_wait_time The time in ms before f is called again
-   * @param max_attempts The maximum number of executions
-   * @param f The function (or lambda) that should be called
-   * @param backoff_increase_factor time between retries is multiplied by this factor on every retry after the first
-   * @see cancel_retry()
-   */
-  // Remove before 2026.7.0
-  ESPDEPRECATED("Use const char* or uint32_t overload instead. Removed in 2026.7.0", "2026.1.0")
+  /// @deprecated set_retry is deprecated. Use set_timeout or set_interval instead. Removed in 2026.8.0.
+  // Remove before 2026.8.0
+  ESPDEPRECATED("set_retry is deprecated and will be removed in 2026.8.0. Use set_timeout or set_interval instead.",
+                "2026.2.0")
   void set_retry(const std::string &name, uint32_t initial_wait_time, uint8_t max_attempts,       // NOLINT
                  std::function<RetryResult(uint8_t)> &&f, float backoff_increase_factor = 1.0f);  // NOLINT
 
+  // Remove before 2026.8.0
+  ESPDEPRECATED("set_retry is deprecated and will be removed in 2026.8.0. Use set_timeout or set_interval instead.",
+                "2026.2.0")
   void set_retry(const char *name, uint32_t initial_wait_time, uint8_t max_attempts,              // NOLINT
                  std::function<RetryResult(uint8_t)> &&f, float backoff_increase_factor = 1.0f);  // NOLINT
 
-  /** Set a retry function with a numeric ID (zero heap allocation).
-   *
-   * @param id The numeric identifier for this retry function
-   * @param initial_wait_time The wait time after the first execution
-   * @param max_attempts The max number of attempts
-   * @param f The function to call
-   * @param backoff_increase_factor The factor to increase the retry interval by
-   */
+  // Remove before 2026.8.0
+  ESPDEPRECATED("set_retry is deprecated and will be removed in 2026.8.0. Use set_timeout or set_interval instead.",
+                "2026.2.0")
   void set_retry(uint32_t id, uint32_t initial_wait_time, uint8_t max_attempts,                   // NOLINT
                  std::function<RetryResult(uint8_t)> &&f, float backoff_increase_factor = 1.0f);  // NOLINT
 
+  // Remove before 2026.8.0
+  ESPDEPRECATED("set_retry is deprecated and will be removed in 2026.8.0. Use set_timeout or set_interval instead.",
+                "2026.2.0")
   void set_retry(uint32_t initial_wait_time, uint8_t max_attempts, std::function<RetryResult(uint8_t)> &&f,  // NOLINT
                  float backoff_increase_factor = 1.0f);                                                      // NOLINT
 
-  /** Cancel a retry function.
-   *
-   * @param name The identifier for this retry function.
-   * @return Whether a retry function was deleted.
-   */
-  // Remove before 2026.7.0
-  ESPDEPRECATED("Use const char* or uint32_t overload instead. Removed in 2026.7.0", "2026.1.0")
+  // Remove before 2026.8.0
+  ESPDEPRECATED("cancel_retry is deprecated and will be removed in 2026.8.0.", "2026.2.0")
   bool cancel_retry(const std::string &name);  // NOLINT
-  bool cancel_retry(const char *name);         // NOLINT
-  bool cancel_retry(uint32_t id);              // NOLINT
+  // Remove before 2026.8.0
+  ESPDEPRECATED("cancel_retry is deprecated and will be removed in 2026.8.0.", "2026.2.0")
+  bool cancel_retry(const char *name);  // NOLINT
+  // Remove before 2026.8.0
+  ESPDEPRECATED("cancel_retry is deprecated and will be removed in 2026.8.0.", "2026.2.0")
+  bool cancel_retry(uint32_t id);  // NOLINT
 
   /** Set a timeout function with a unique name.
    *

esphome/core/scheduler.cpp

@@ -252,6 +252,11 @@ bool HOT Scheduler::cancel_interval(Component *component, uint32_t id) {
   return this->cancel_item_(component, NameType::NUMERIC_ID, nullptr, id, SchedulerItem::INTERVAL);
 }
 
+// Suppress deprecation warnings for RetryResult usage in the still-present (but deprecated) retry implementation.
+// Remove before 2026.8.0 along with all retry code.
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+
 struct RetryArgs {
   // Ordered to minimize padding on 32-bit systems
   std::function<RetryResult(uint8_t)> func;
@@ -364,6 +369,8 @@ bool HOT Scheduler::cancel_retry(Component *component, uint32_t id) {
   return this->cancel_retry_(component, NameType::NUMERIC_ID, nullptr, id);
 }
 
+#pragma GCC diagnostic pop  // End suppression of deprecated RetryResult warnings
+
 optional<uint32_t> HOT Scheduler::next_schedule_in(uint32_t now) {
   // IMPORTANT: This method should only be called from the main thread (loop task).
   // It performs cleanup and accesses items_[0] without holding a lock, which is only

esphome/core/scheduler.h

@@ -72,18 +72,30 @@ class Scheduler {
   bool cancel_interval(Component *component, const char *name);
   bool cancel_interval(Component *component, uint32_t id);
 
-  ESPDEPRECATED("Use const char* or uint32_t overload instead. Removed in 2026.7.0", "2026.1.0")
+  // Remove before 2026.8.0
+  ESPDEPRECATED("set_retry is deprecated and will be removed in 2026.8.0. Use set_timeout or set_interval instead.",
+                "2026.2.0")
   void set_retry(Component *component, const std::string &name, uint32_t initial_wait_time, uint8_t max_attempts,
                  std::function<RetryResult(uint8_t)> func, float backoff_increase_factor = 1.0f);
+  // Remove before 2026.8.0
+  ESPDEPRECATED("set_retry is deprecated and will be removed in 2026.8.0. Use set_timeout or set_interval instead.",
+                "2026.2.0")
   void set_retry(Component *component, const char *name, uint32_t initial_wait_time, uint8_t max_attempts,
                  std::function<RetryResult(uint8_t)> func, float backoff_increase_factor = 1.0f);
-  /// Set a retry with a numeric ID (zero heap allocation)
+  // Remove before 2026.8.0
+  ESPDEPRECATED("set_retry is deprecated and will be removed in 2026.8.0. Use set_timeout or set_interval instead.",
+                "2026.2.0")
   void set_retry(Component *component, uint32_t id, uint32_t initial_wait_time, uint8_t max_attempts,
                  std::function<RetryResult(uint8_t)> func, float backoff_increase_factor = 1.0f);
 
-  ESPDEPRECATED("Use const char* or uint32_t overload instead. Removed in 2026.7.0", "2026.1.0")
+  // Remove before 2026.8.0
+  ESPDEPRECATED("cancel_retry is deprecated and will be removed in 2026.8.0.", "2026.2.0")
   bool cancel_retry(Component *component, const std::string &name);
+  // Remove before 2026.8.0
+  ESPDEPRECATED("cancel_retry is deprecated and will be removed in 2026.8.0.", "2026.2.0")
   bool cancel_retry(Component *component, const char *name);
+  // Remove before 2026.8.0
+  ESPDEPRECATED("cancel_retry is deprecated and will be removed in 2026.8.0.", "2026.2.0")
   bool cancel_retry(Component *component, uint32_t id);
 
   // Calculate when the next scheduled item should run
@@ -231,11 +243,14 @@ class Scheduler {
                          uint32_t hash_or_id, uint32_t delay, std::function<void()> func, bool is_retry = false,
                          bool skip_cancel = false);
 
-  // Common implementation for retry
+  // Common implementation for retry - Remove before 2026.8.0
   // name_type determines storage type: STATIC_STRING uses static_name, others use hash_or_id
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
   void set_retry_common_(Component *component, NameType name_type, const char *static_name, uint32_t hash_or_id,
                          uint32_t initial_wait_time, uint8_t max_attempts, std::function<RetryResult(uint8_t)> func,
                          float backoff_increase_factor);
+#pragma GCC diagnostic pop
   // Common implementation for cancel_retry
   bool cancel_retry_(Component *component, NameType name_type, const char *static_name, uint32_t hash_or_id);
 

esphome/cpp_generator.py

@@ -247,6 +247,23 @@ class LogStringLiteral(Literal):
         return f"LOG_STR({cpp_string_escape(self.string)})"
 
 
+class FlashStringLiteral(Literal):
+    """A string literal wrapped in ESPHOME_F() for PROGMEM storage on ESP8266.
+
+    On ESP8266, ESPHOME_F(s) expands to F(s) which stores the string in flash (PROGMEM).
+    On other platforms, ESPHOME_F(s) expands to plain s (no-op).
+    """
+
+    __slots__ = ("string",)
+
+    def __init__(self, string: str) -> None:
+        super().__init__()
+        self.string = string
+
+    def __str__(self) -> str:
+        return f"ESPHOME_F({cpp_string_escape(self.string)})"
+
+
 class IntLiteral(Literal):
     __slots__ = ("i",)
 
@@ -761,6 +778,15 @@ async def templatable(
     if is_template(value):
         return await process_lambda(value, args, return_type=output_type)
     if to_exp is None:
+        # Automatically wrap static strings in ESPHOME_F() for PROGMEM storage on ESP8266.
+        # On other platforms ESPHOME_F() is a no-op returning const char*.
+        # Lazy import to avoid circular dependency (cpp_generator <-> cpp_types).
+        # Identity check (is) avoids brittle string comparison.
+        if isinstance(value, str) and output_type is not None:
+            from esphome.cpp_types import std_string
+
+            if output_type is std_string:
+                return FlashStringLiteral(value)
         return value
     if isinstance(to_exp, dict):
         return to_exp[value]

script/api_protobuf/api_protobuf.py

@@ -2881,9 +2881,82 @@ static const char *const TAG = "api.service";
 
     cases = list(RECEIVE_CASES.items())
     cases.sort()
+
+    serv = file.service[0]
+
+    # Build a mapping of message input types to their authentication requirements
+    message_auth_map: dict[str, bool] = {}
+    message_conn_map: dict[str, bool] = {}
+
+    for m in serv.method:
+        inp = m.input_type[1:]
+        needs_conn = get_opt(m, pb.needs_setup_connection, True)
+        needs_auth = get_opt(m, pb.needs_authentication, True)
+
+        # Store authentication requirements for message types
+        message_auth_map[inp] = needs_auth
+        message_conn_map[inp] = needs_conn
+
+    # Categorize messages by their authentication requirements
+    no_conn_ids: set[int] = set()
+    conn_only_ids: set[int] = set()
+
+    for id_, (_, _, case_msg_name) in cases:
+        if case_msg_name in message_auth_map:
+            needs_auth = message_auth_map[case_msg_name]
+            needs_conn = message_conn_map[case_msg_name]
+
+            if not needs_conn:
+                no_conn_ids.add(id_)
+            elif not needs_auth:
+                conn_only_ids.add(id_)
+
+    # Helper to generate case statements with ifdefs
+    def generate_cases(ids: set[int], comment: str) -> str:
+        result = ""
+        for id_ in sorted(ids):
+            _, ifdef, msg_name = RECEIVE_CASES[id_]
+            if ifdef:
+                result += f"#ifdef {ifdef}\n"
+            result += f"    case {msg_name}::MESSAGE_TYPE:  {comment}\n"
+            if ifdef:
+                result += "#endif\n"
+        return result
+
+    # Generate read_message with auth check before dispatch
     hpp += " protected:\n"
     hpp += "  void read_message(uint32_t msg_size, uint32_t msg_type, const uint8_t *msg_data) override;\n"
+
     out = f"void {class_name}::read_message(uint32_t msg_size, uint32_t msg_type, const uint8_t *msg_data) {{\n"
+
+    # Auth check block before dispatch switch
+    out += "  // Check authentication/connection requirements\n"
+    if no_conn_ids or conn_only_ids:
+        out += "  switch (msg_type) {\n"
+
+        if no_conn_ids:
+            out += generate_cases(no_conn_ids, "// No setup required")
+            out += "      break;\n"
+
+        if conn_only_ids:
+            out += generate_cases(conn_only_ids, "// Connection setup only")
+            out += "      if (!this->check_connection_setup_()) {\n"
+            out += "        return;\n"
+            out += "      }\n"
+            out += "      break;\n"
+
+        out += "    default:\n"
+        out += "      if (!this->check_authenticated_()) {\n"
+        out += "        return;\n"
+        out += "      }\n"
+        out += "      break;\n"
+        out += "  }\n"
+    else:
+        out += "  if (!this->check_authenticated_()) {\n"
+        out += "    return;\n"
+        out += "  }\n"
+
+    # Dispatch switch
     out += "  switch (msg_type) {\n"
     for i, (case, ifdef, message_name) in cases:
         if ifdef is not None:
@@ -2902,89 +2975,6 @@ static const char *const TAG = "api.service";
     cpp += out
     hpp += "};\n"
 
-    serv = file.service[0]
-    class_name = "APIServerConnection"
-    hpp += "\n"
-    hpp += f"class {class_name} : public {class_name}Base {{\n"
-    hpp_protected = ""
-    cpp += "\n"
-
-    # Build a mapping of message input types to their authentication requirements
-    message_auth_map: dict[str, bool] = {}
-    message_conn_map: dict[str, bool] = {}
-
-    for m in serv.method:
-        inp = m.input_type[1:]
-        needs_conn = get_opt(m, pb.needs_setup_connection, True)
-        needs_auth = get_opt(m, pb.needs_authentication, True)
-
-        # Store authentication requirements for message types
-        message_auth_map[inp] = needs_auth
-        message_conn_map[inp] = needs_conn
-
-    # Generate optimized read_message with authentication checking
-    # Categorize messages by their authentication requirements
-    no_conn_ids: set[int] = set()
-    conn_only_ids: set[int] = set()
-
-    for id_, (_, _, case_msg_name) in cases:
-        if case_msg_name in message_auth_map:
-            needs_auth = message_auth_map[case_msg_name]
-            needs_conn = message_conn_map[case_msg_name]
-
-            if not needs_conn:
-                no_conn_ids.add(id_)
-            elif not needs_auth:
-                conn_only_ids.add(id_)
-
-    # Generate override if we have messages that skip checks
-    if no_conn_ids or conn_only_ids:
-        # Helper to generate case statements with ifdefs
-        def generate_cases(ids: set[int], comment: str) -> str:
-            result = ""
-            for id_ in sorted(ids):
-                _, ifdef, msg_name = RECEIVE_CASES[id_]
-                if ifdef:
-                    result += f"#ifdef {ifdef}\n"
-                result += f"    case {msg_name}::MESSAGE_TYPE:  {comment}\n"
-                if ifdef:
-                    result += "#endif\n"
-            return result
-
-        hpp_protected += "  void read_message(uint32_t msg_size, uint32_t msg_type, const uint8_t *msg_data) override;\n"
-
-        cpp += f"\nvoid {class_name}::read_message(uint32_t msg_size, uint32_t msg_type, const uint8_t *msg_data) {{\n"
-        cpp += "  // Check authentication/connection requirements for messages\n"
-        cpp += "  switch (msg_type) {\n"
-
-        # Messages that don't need any checks
-        if no_conn_ids:
-            cpp += generate_cases(no_conn_ids, "// No setup required")
-            cpp += "      break;  // Skip all checks for these messages\n"
-
-        # Messages that only need connection setup
-        if conn_only_ids:
-            cpp += generate_cases(conn_only_ids, "// Connection setup only")
-            cpp += "      if (!this->check_connection_setup_()) {\n"
-            cpp += "        return;  // Connection not setup\n"
-            cpp += "      }\n"
-            cpp += "      break;\n"
-
-        cpp += "    default:\n"
-        cpp += "      // All other messages require authentication (which includes connection check)\n"
-        cpp += "      if (!this->check_authenticated_()) {\n"
-        cpp += "        return;  // Authentication failed\n"
-        cpp += "      }\n"
-        cpp += "      break;\n"
-        cpp += "  }\n\n"
-        cpp += "  // Call base implementation to process the message\n"
-        cpp += f"  {class_name}Base::read_message(msg_size, msg_type, msg_data);\n"
-        cpp += "}\n"
-
-    hpp += " protected:\n"
-    hpp += hpp_protected
-    hpp += "};\n"
-
     hpp += """\
 
 }  // namespace esphome::api

script/ci-custom.py

@@ -756,6 +756,53 @@ def lint_no_sprintf(fname, match):
     )
 
 
+@lint_re_check(
+    # Match std::to_string() or unqualified to_string() calls
+    # The esphome namespace has "using std::to_string;" so unqualified calls resolve to std::to_string
+    # Use negative lookbehind for unqualified calls to avoid matching:
+    #   - Function definitions: "const char *to_string(" or "std::string to_string("
+    #   - Method definitions: "Class::to_string("
+    #   - Method calls: ".to_string(" or "->to_string("
+    #   - Other identifiers: "_to_string("
+    # Also explicitly match std::to_string since : is in the lookbehind
+    r"(?:(?<![*&.\w>:])to_string|std\s*::\s*to_string)\s*\(" + CPP_RE_EOL,
+    include=cpp_include,
+    exclude=[
+        # Vendored library
+        "esphome/components/http_request/httplib.h",
+        # Deprecated helpers that return std::string
+        "esphome/core/helpers.cpp",
+        # The using declaration itself
+        "esphome/core/helpers.h",
+        # Test fixtures - not production embedded code
+        "tests/integration/fixtures/*",
+    ],
+)
+def lint_no_std_to_string(fname, match):
+    return (
+        f"{highlight('std::to_string()')} (including unqualified {highlight('to_string()')}) "
+        f"allocates heap memory. On long-running embedded devices, repeated heap allocations "
+        f"fragment memory over time.\n"
+        f"Please use {highlight('snprintf()')} with a stack buffer instead.\n"
+        f"\n"
+        f"Buffer sizes and format specifiers (sizes include sign and null terminator):\n"
+        f"  uint8_t:          4 chars   - %u (or PRIu8)\n"
+        f"  int8_t:           5 chars   - %d (or PRId8)\n"
+        f"  uint16_t:         6 chars   - %u (or PRIu16)\n"
+        f"  int16_t:          7 chars   - %d (or PRId16)\n"
+        f"  uint32_t:         11 chars  - %" + "PRIu32\n"
+        "  int32_t:          12 chars  - %" + "PRId32\n"
+        "  uint64_t:         21 chars  - %" + "PRIu64\n"
+        "  int64_t:          21 chars  - %" + "PRId64\n"
+        f"  float/double:     24 chars  - %.8g (15 digits + sign + decimal + e+XXX)\n"
+        f"                    317 chars - %f (for DBL_MAX: 309 int digits + decimal + 6 frac + sign)\n"
+        f"\n"
+        f"For sensor values, use value_accuracy_to_buf() from helpers.h.\n"
+        f'Example: char buf[11]; snprintf(buf, sizeof(buf), "%" PRIu32, value);\n'
+        f"(If strictly necessary, add `{highlight('// NOLINT')}` to the end of the line)"
+    )
+
+
 @lint_re_check(
     # Match scanf family functions: scanf, sscanf, fscanf, vscanf, vsscanf, vfscanf
     # Also match std:: prefixed versions

tests/unit_tests/test_cpp_generator.py

@@ -248,6 +248,12 @@ class TestLiterals:
             (cg.FloatLiteral(4.2), "4.2f"),
             (cg.FloatLiteral(1.23456789), "1.23456789f"),
             (cg.FloatLiteral(math.nan), "NAN"),
+            (cg.FlashStringLiteral("hello"), 'ESPHOME_F("hello")'),
+            (cg.FlashStringLiteral(""), 'ESPHOME_F("")'),
+            (
+                cg.FlashStringLiteral('quote"here'),
+                'ESPHOME_F("quote\\042here")',
+            ),
         ),
     )
     def test_str__simple(self, target: cg.Literal, expected: str):
@@ -624,3 +630,75 @@ class TestProcessLambda:
         # Test invalid tuple format (single element)
         with pytest.raises(AssertionError):
             await cg.process_lambda(lambda_obj, [(int,)])
+
+
+@pytest.mark.asyncio
+async def test_templatable__string_with_std_string_returns_flash_literal() -> None:
+    """Static string with std::string output_type returns FlashStringLiteral."""
+    result = await cg.templatable("hello", [], ct.std_string)
+
+    assert isinstance(result, cg.FlashStringLiteral)
+    assert str(result) == 'ESPHOME_F("hello")'
+
+
+@pytest.mark.asyncio
+async def test_templatable__empty_string_with_std_string() -> None:
+    """Empty static string with std::string output_type returns FlashStringLiteral."""
+    result = await cg.templatable("", [], ct.std_string)
+
+    assert isinstance(result, cg.FlashStringLiteral)
+    assert str(result) == 'ESPHOME_F("")'
+
+
+@pytest.mark.asyncio
+async def test_templatable__string_with_none_output_type() -> None:
+    """Static string with output_type=None returns raw string (no wrapping)."""
+    result = await cg.templatable("hello", [], None)
+
+    assert isinstance(result, str)
+    assert result == "hello"
+
+
+@pytest.mark.asyncio
+async def test_templatable__int_with_std_string() -> None:
+    """Non-string value with std::string output_type returns raw value."""
+    result = await cg.templatable(42, [], ct.std_string)
+
+    assert result == 42
+
+
+@pytest.mark.asyncio
+async def test_templatable__string_with_non_string_output_type() -> None:
+    """Static string with non-std::string output_type returns raw string."""
+    result = await cg.templatable("hello", [], ct.bool_)
+
+    assert isinstance(result, str)
+    assert result == "hello"
+
+
+@pytest.mark.asyncio
+async def test_templatable__with_to_exp_callable() -> None:
+    """When to_exp is provided, it is applied to non-template values."""
+    result = await cg.templatable(42, [], None, to_exp=lambda x: x * 2)
+
+    assert result == 84
+
+
+@pytest.mark.asyncio
+async def test_templatable__with_to_exp_dict() -> None:
+    """When to_exp is a dict, value is looked up."""
+    mapping: dict[str, int] = {"on": 1, "off": 0}
+    result = await cg.templatable("on", [], None, to_exp=mapping)
+
+    assert result == 1
+
+
+@pytest.mark.asyncio
+async def test_templatable__lambda_with_std_string() -> None:
+    """Lambda value returns LambdaExpression, not FlashStringLiteral."""
+    from esphome.core import Lambda
+
+    lambda_obj = Lambda('return "hello";')
+    result = await cg.templatable(lambda_obj, [], ct.std_string)
+
+    assert isinstance(result, cg.LambdaExpression)