CODEOWNERS

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

.github/actions/build-image/action.yaml

@@ -47,7 +47,7 @@ runs:
 
     - name: Build and push to ghcr by digest
       id: build-ghcr
-      uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83 # v6.18.0
+      uses: docker/build-push-action@601a80b39c9405e50806ae38af30926f9d957c47 # v6.19.1
       env:
         DOCKER_BUILD_SUMMARY: false
         DOCKER_BUILD_RECORD_UPLOAD: false
@@ -73,7 +73,7 @@ runs:
 
     - name: Build and push to dockerhub by digest
       id: build-dockerhub
-      uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83 # v6.18.0
+      uses: docker/build-push-action@601a80b39c9405e50806ae38af30926f9d957c47 # v6.19.1
       env:
         DOCKER_BUILD_SUMMARY: false
         DOCKER_BUILD_RECORD_UPLOAD: false

CODEOWNERS

@@ -429,6 +429,7 @@ esphome/components/sen21231/* @shreyaskarnik
 esphome/components/sen5x/* @martgras
 esphome/components/sensirion_common/* @martgras
 esphome/components/sensor/* @esphome/core
+esphome/components/serial_proxy/* @kbx81
 esphome/components/sfa30/* @ghsensdev
 esphome/components/sgp40/* @SenexCrenshaw
 esphome/components/sgp4x/* @martgras @SenexCrenshaw

esphome/components/api/api.proto

@@ -69,6 +69,12 @@ service APIConnection {
   rpc zwave_proxy_request(ZWaveProxyRequest) returns (void) {}
 
   rpc infrared_rf_transmit_raw_timings(InfraredRFTransmitRawTimingsRequest) returns (void) {}
+
+  rpc serial_proxy_configure(SerialProxyConfigureRequest) returns (void) {}
+  rpc serial_proxy_write(SerialProxyWriteRequest) returns (void) {}
+  rpc serial_proxy_set_modem_pins(SerialProxySetModemPinsRequest) returns (void) {}
+  rpc serial_proxy_get_modem_pins(SerialProxyGetModemPinsRequest) returns (void) {}
+  rpc serial_proxy_flush(SerialProxyFlushRequest) returns (void) {}
 }
 
 
@@ -260,6 +266,9 @@ message DeviceInfoResponse {
   // Indicates if Z-Wave proxy support is available and features supported
   uint32 zwave_proxy_feature_flags = 23 [(field_ifdef) = "USE_ZWAVE_PROXY"];
   uint32 zwave_home_id = 24 [(field_ifdef) = "USE_ZWAVE_PROXY"];
+
+  // Number of serial proxy instances available on the device
+  uint32 serial_proxy_count = 25 [(field_ifdef) = "USE_SERIAL_PROXY"];
 }
 
 message ListEntitiesRequest {
@@ -2488,3 +2497,87 @@ message InfraredRFReceiveEvent {
   fixed32 key = 2;                                    // Key identifying the receiver instance
   repeated sint32 timings = 3 [packed = true, (container_pointer_no_template) = "std::vector<int32_t>"];  // Raw timings in microseconds (zigzag-encoded): alternating mark/space periods
 }
+
+// ==================== SERIAL PROXY ====================
+
+enum SerialProxyParity {
+  SERIAL_PROXY_PARITY_NONE = 0;
+  SERIAL_PROXY_PARITY_EVEN = 1;
+  SERIAL_PROXY_PARITY_ODD = 2;
+}
+
+// Configure UART parameters for a serial proxy instance
+message SerialProxyConfigureRequest {
+  option (id) = 138;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;          // Instance index (0-based)
+  uint32 baudrate = 2;          // Baud rate in bits per second
+  bool flow_control = 3;        // Enable hardware flow control
+  SerialProxyParity parity = 4; // Parity setting
+  uint32 stop_bits = 5;         // Number of stop bits (1 or 2)
+  uint32 data_size = 6;         // Number of data bits (5-8)
+}
+
+// Data received from a serial device, forwarded to clients
+message SerialProxyDataReceived {
+  option (id) = 139;
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_SERIAL_PROXY";
+  option (no_delay) = true;
+
+  uint32 instance = 1;          // Instance index (0-based)
+  bytes data = 2;               // Raw data received from the serial device
+}
+
+// Write data to a serial device
+message SerialProxyWriteRequest {
+  option (id) = 140;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_SERIAL_PROXY";
+  option (no_delay) = true;
+
+  uint32 instance = 1;          // Instance index (0-based)
+  bytes data = 2;               // Raw data to write to the serial device
+}
+
+// Set modem control pin states (RTS and DTR)
+message SerialProxySetModemPinsRequest {
+  option (id) = 141;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;          // Instance index (0-based)
+  bool rts = 2;                 // Desired RTS pin state
+  bool dtr = 3;                 // Desired DTR pin state
+}
+
+// Request current modem control pin states
+message SerialProxyGetModemPinsRequest {
+  option (id) = 142;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;          // Instance index (0-based)
+}
+
+// Response with current modem control pin states
+message SerialProxyGetModemPinsResponse {
+  option (id) = 143;
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;          // Instance index (0-based)
+  bool rts = 2;                 // Current RTS pin state
+  bool dtr = 3;                 // Current DTR pin state
+}
+
+// Flush the serial port (block until all TX data is sent)
+message SerialProxyFlushRequest {
+  option (id) = 144;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;          // Instance index (0-based)
+}

esphome/components/api/api_connection.cpp

@@ -1413,6 +1413,66 @@ void APIConnection::send_infrared_rf_receive_event(const InfraredRFReceiveEvent
 }
 #endif
 
+#ifdef USE_SERIAL_PROXY
+void APIConnection::on_serial_proxy_configure_request(const SerialProxyConfigureRequest &msg) {
+  auto &proxies = App.get_serial_proxies();
+  if (msg.instance >= proxies.size()) {
+    ESP_LOGW(TAG, "Serial proxy instance %u out of range (max %u)", msg.instance,
+             static_cast<uint32_t>(proxies.size()));
+    return;
+  }
+  proxies[msg.instance]->configure(msg.baudrate, msg.flow_control, static_cast<uint8_t>(msg.parity), msg.stop_bits,
+                                   msg.data_size);
+}
+
+void APIConnection::on_serial_proxy_write_request(const SerialProxyWriteRequest &msg) {
+  auto &proxies = App.get_serial_proxies();
+  if (msg.instance >= proxies.size()) {
+    ESP_LOGW(TAG, "Serial proxy instance %u out of range", msg.instance);
+    return;
+  }
+  proxies[msg.instance]->write(msg.data, msg.data_len);
+}
+
+void APIConnection::on_serial_proxy_set_modem_pins_request(const SerialProxySetModemPinsRequest &msg) {
+  auto &proxies = App.get_serial_proxies();
+  if (msg.instance >= proxies.size()) {
+    ESP_LOGW(TAG, "Serial proxy instance %u out of range", msg.instance);
+    return;
+  }
+  proxies[msg.instance]->set_modem_pins(msg.rts, msg.dtr);
+}
+
+void APIConnection::on_serial_proxy_get_modem_pins_request(const SerialProxyGetModemPinsRequest &msg) {
+  auto &proxies = App.get_serial_proxies();
+  if (msg.instance >= proxies.size()) {
+    ESP_LOGW(TAG, "Serial proxy instance %u out of range", msg.instance);
+    return;
+  }
+  bool rts, dtr;
+  proxies[msg.instance]->get_modem_pins(rts, dtr);
+
+  SerialProxyGetModemPinsResponse resp{};
+  resp.instance = msg.instance;
+  resp.rts = rts;
+  resp.dtr = dtr;
+  this->send_message(resp, SerialProxyGetModemPinsResponse::MESSAGE_TYPE);
+}
+
+void APIConnection::on_serial_proxy_flush_request(const SerialProxyFlushRequest &msg) {
+  auto &proxies = App.get_serial_proxies();
+  if (msg.instance >= proxies.size()) {
+    ESP_LOGW(TAG, "Serial proxy instance %u out of range", msg.instance);
+    return;
+  }
+  proxies[msg.instance]->flush_port();
+}
+
+void APIConnection::send_serial_proxy_data(const SerialProxyDataReceived &msg) {
+  this->send_message(msg, SerialProxyDataReceived::MESSAGE_TYPE);
+}
+#endif
+
 #ifdef USE_INFRARED
 uint16_t APIConnection::try_send_infrared_info(EntityBase *entity, APIConnection *conn, uint32_t remaining_size) {
   auto *infrared = static_cast<infrared::Infrared *>(entity);
@@ -1510,7 +1570,7 @@ bool APIConnection::send_hello_response_(const HelloRequest &msg) {
   this->client_api_version_major_ = msg.api_version_major;
   this->client_api_version_minor_ = msg.api_version_minor;
   char peername[socket::SOCKADDR_STR_LEN];
-  ESP_LOGV(TAG, "Hello from client: '%s' | %s | API Version %" PRIu32 ".%" PRIu32, this->helper_->get_client_name(),
+  ESP_LOGV(TAG, "Hello from client: '%s' | %s | API Version %" PRIu16 ".%" PRIu16, this->helper_->get_client_name(),
            this->helper_->get_peername_to(peername), this->client_api_version_major_, this->client_api_version_minor_);
 
   HelloResponse resp;
@@ -1627,6 +1687,9 @@ bool APIConnection::send_device_info_response_() {
   resp.zwave_proxy_feature_flags = zwave_proxy::global_zwave_proxy->get_feature_flags();
   resp.zwave_home_id = zwave_proxy::global_zwave_proxy->get_home_id();
 #endif
+#ifdef USE_SERIAL_PROXY
+  resp.serial_proxy_count = App.get_serial_proxies().size();
+#endif
 #ifdef USE_API_NOISE
   resp.api_encryption_supported = true;
 #endif
@@ -1921,10 +1984,6 @@ bool APIConnection::schedule_batch_() {
 }
 
 void APIConnection::process_batch_() {
-  // Ensure MessageInfo remains trivially destructible for our placement new approach
-  static_assert(std::is_trivially_destructible<MessageInfo>::value,
-                "MessageInfo must remain trivially destructible with this placement-new approach");
-
   if (this->deferred_batch_.empty()) {
     this->flags_.batch_scheduled = false;
     return;
@@ -1949,6 +2008,10 @@ void APIConnection::process_batch_() {
   for (size_t i = 0; i < num_items; i++) {
     total_estimated_size += this->deferred_batch_[i].estimated_size;
   }
+  // Clamp to MAX_BATCH_PACKET_SIZE — we won't send more than that per batch
+  if (total_estimated_size > MAX_BATCH_PACKET_SIZE) {
+    total_estimated_size = MAX_BATCH_PACKET_SIZE;
+  }
 
   this->prepare_first_message_buffer(shared_buf, header_padding, total_estimated_size);
 
@@ -1972,7 +2035,20 @@ void APIConnection::process_batch_() {
     return;
   }
 
-  size_t messages_to_process = std::min(num_items, MAX_MESSAGES_PER_BATCH);
+  // Multi-message path — heavy stack frame isolated in separate noinline function
+  this->process_batch_multi_(shared_buf, num_items, header_padding, footer_size);
+}
+
+// Separated from process_batch_() so the single-message fast path gets a minimal
+// stack frame without the MAX_MESSAGES_PER_BATCH * sizeof(MessageInfo) array.
+void APIConnection::process_batch_multi_(std::vector<uint8_t> &shared_buf, size_t num_items, uint8_t header_padding,
+                                         uint8_t footer_size) {
+  // Ensure MessageInfo remains trivially destructible for our placement new approach
+  static_assert(std::is_trivially_destructible<MessageInfo>::value,
+                "MessageInfo must remain trivially destructible with this placement-new approach");
+
+  const size_t messages_to_process = std::min(num_items, MAX_MESSAGES_PER_BATCH);
+  const uint8_t frame_overhead = header_padding + footer_size;
 
   // Stack-allocated array for message info
   alignas(MessageInfo) char message_info_storage[MAX_MESSAGES_PER_BATCH * sizeof(MessageInfo)];
@@ -1999,7 +2075,7 @@ void APIConnection::process_batch_() {
 
     // Message was encoded successfully
     // payload_size is header_padding + actual payload size + footer_size
-    uint16_t proto_payload_size = payload_size - header_padding - footer_size;
+    uint16_t proto_payload_size = payload_size - frame_overhead;
     // Use placement new to construct MessageInfo in pre-allocated stack array
     // This avoids default-constructing all MAX_MESSAGES_PER_BATCH elements
     // Explicit destruction is not needed because MessageInfo is trivially destructible,
@@ -2015,42 +2091,38 @@ void APIConnection::process_batch_() {
     current_offset = shared_buf.size() + footer_size;
   }
 
-  if (items_processed == 0) {
-    this->deferred_batch_.clear();
-    return;
-  }
+  if (items_processed > 0) {
+    // Add footer space for the last message (for Noise protocol MAC)
+    if (footer_size > 0) {
+      shared_buf.resize(shared_buf.size() + footer_size);
+    }
 
-  // Add footer space for the last message (for Noise protocol MAC)
-  if (footer_size > 0) {
-    shared_buf.resize(shared_buf.size() + footer_size);
-  }
-
-  // Send all collected messages
-  APIError err = this->helper_->write_protobuf_messages(ProtoWriteBuffer{&shared_buf},
-                                                        std::span<const MessageInfo>(message_info, items_processed));
-  if (err != APIError::OK && err != APIError::WOULD_BLOCK) {
-    this->fatal_error_with_log_(LOG_STR("Batch write failed"), err);
-  }
+    // Send all collected messages
+    APIError err = this->helper_->write_protobuf_messages(ProtoWriteBuffer{&shared_buf},
+                                                          std::span<const MessageInfo>(message_info, items_processed));
+    if (err != APIError::OK && err != APIError::WOULD_BLOCK) {
+      this->fatal_error_with_log_(LOG_STR("Batch write failed"), err);
+    }
 
 #ifdef HAS_PROTO_MESSAGE_DUMP
-  // Log messages after send attempt for VV debugging
-  // It's safe to use the buffer for logging at this point regardless of send result
-  for (size_t i = 0; i < items_processed; i++) {
-    const auto &item = this->deferred_batch_[i];
-    this->log_batch_item_(item);
-  }
+    // Log messages after send attempt for VV debugging
+    // It's safe to use the buffer for logging at this point regardless of send result
+    for (size_t i = 0; i < items_processed; i++) {
+      const auto &item = this->deferred_batch_[i];
+      this->log_batch_item_(item);
+    }
 #endif
 
-  // Handle remaining items more efficiently
-  if (items_processed < this->deferred_batch_.size()) {
-    // Remove processed items from the beginning
-    this->deferred_batch_.remove_front(items_processed);
-    // Reschedule for remaining items
-    this->schedule_batch_();
-  } else {
-    // All items processed
-    this->clear_batch_();
+    // Partial batch — remove processed items and reschedule
+    if (items_processed < this->deferred_batch_.size()) {
+      this->deferred_batch_.remove_front(items_processed);
+      this->schedule_batch_();
+      return;
+    }
   }
+
+  // All items processed (or none could be processed)
+  this->clear_batch_();
 }
 
 // Dispatch message encoding based on message_type

esphome/components/api/api_connection.h

@@ -182,6 +182,15 @@ class APIConnection final : public APIServerConnectionBase {
   void send_infrared_rf_receive_event(const InfraredRFReceiveEvent &msg);
 #endif
 
+#ifdef USE_SERIAL_PROXY
+  void on_serial_proxy_configure_request(const SerialProxyConfigureRequest &msg) override;
+  void on_serial_proxy_write_request(const SerialProxyWriteRequest &msg) override;
+  void on_serial_proxy_set_modem_pins_request(const SerialProxySetModemPinsRequest &msg) override;
+  void on_serial_proxy_get_modem_pins_request(const SerialProxyGetModemPinsRequest &msg) override;
+  void on_serial_proxy_flush_request(const SerialProxyFlushRequest &msg) override;
+  void send_serial_proxy_data(const SerialProxyDataReceived &msg);
+#endif
+
 #ifdef USE_EVENT
   void send_event(event::Event *event);
 #endif
@@ -548,8 +557,8 @@ class APIConnection final : public APIServerConnectionBase {
       batch_start_time = 0;
     }
 
-    // Remove processed items from the front
-    void remove_front(size_t count) { items.erase(items.begin(), items.begin() + count); }
+    // Remove processed items from the front — noinline to keep memmove out of warm callers
+    void remove_front(size_t count) __attribute__((noinline)) { items.erase(items.begin(), items.begin() + count); }
 
     bool empty() const { return items.empty(); }
     size_t size() const { return items.size(); }
@@ -621,6 +630,8 @@ class APIConnection final : public APIServerConnectionBase {
 
   bool schedule_batch_();
   void process_batch_();
+  void process_batch_multi_(std::vector<uint8_t> &shared_buf, size_t num_items, uint8_t header_padding,
+                            uint8_t footer_size) __attribute__((noinline));
   void clear_batch_() {
     this->deferred_batch_.clear();
     this->flags_.batch_scheduled = false;

esphome/components/api/api_frame_helper_plaintext.cpp

@@ -295,9 +295,8 @@ APIError APIPlaintextFrameHelper::write_protobuf_messages(ProtoWriteBuffer buffe
     buf_start[header_offset] = 0x00;  // indicator
 
     // Encode varints directly into buffer
-    ProtoVarInt(msg.payload_size).encode_to_buffer_unchecked(buf_start + header_offset + 1, size_varint_len);
-    ProtoVarInt(msg.message_type)
-        .encode_to_buffer_unchecked(buf_start + header_offset + 1 + size_varint_len, type_varint_len);
+    encode_varint_to_buffer(msg.payload_size, buf_start + header_offset + 1);
+    encode_varint_to_buffer(msg.message_type, buf_start + header_offset + 1 + size_varint_len);
 
     // Add iovec for this message (header + payload)
     size_t msg_len = static_cast<size_t>(total_header_len + msg.payload_size);

esphome/components/api/api_pb2.cpp

@@ -119,6 +119,9 @@ void DeviceInfoResponse::encode(ProtoWriteBuffer buffer) const {
 #ifdef USE_ZWAVE_PROXY
   buffer.encode_uint32(24, this->zwave_home_id);
 #endif
+#ifdef USE_SERIAL_PROXY
+  buffer.encode_uint32(25, this->serial_proxy_count);
+#endif
 }
 void DeviceInfoResponse::calculate_size(ProtoSize &size) const {
   size.add_length(1, this->name.size());
@@ -174,6 +177,9 @@ void DeviceInfoResponse::calculate_size(ProtoSize &size) const {
 #ifdef USE_ZWAVE_PROXY
   size.add_uint32(2, this->zwave_home_id);
 #endif
+#ifdef USE_SERIAL_PROXY
+  size.add_uint32(2, this->serial_proxy_count);
+#endif
 }
 #ifdef USE_BINARY_SENSOR
 void ListEntitiesBinarySensorResponse::encode(ProtoWriteBuffer buffer) const {
@@ -3440,5 +3446,108 @@ void InfraredRFReceiveEvent::calculate_size(ProtoSize &size) const {
   }
 }
 #endif
+#ifdef USE_SERIAL_PROXY
+bool SerialProxyConfigureRequest::decode_varint(uint32_t field_id, ProtoVarInt value) {
+  switch (field_id) {
+    case 1:
+      this->instance = value.as_uint32();
+      break;
+    case 2:
+      this->baudrate = value.as_uint32();
+      break;
+    case 3:
+      this->flow_control = value.as_bool();
+      break;
+    case 4:
+      this->parity = static_cast<enums::SerialProxyParity>(value.as_uint32());
+      break;
+    case 5:
+      this->stop_bits = value.as_uint32();
+      break;
+    case 6:
+      this->data_size = value.as_uint32();
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+void SerialProxyDataReceived::encode(ProtoWriteBuffer buffer) const {
+  buffer.encode_uint32(1, this->instance);
+  buffer.encode_bytes(2, this->data_ptr_, this->data_len_);
+}
+void SerialProxyDataReceived::calculate_size(ProtoSize &size) const {
+  size.add_uint32(1, this->instance);
+  size.add_length(1, this->data_len_);
+}
+bool SerialProxyWriteRequest::decode_varint(uint32_t field_id, ProtoVarInt value) {
+  switch (field_id) {
+    case 1:
+      this->instance = value.as_uint32();
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+bool SerialProxyWriteRequest::decode_length(uint32_t field_id, ProtoLengthDelimited value) {
+  switch (field_id) {
+    case 2: {
+      this->data = value.data();
+      this->data_len = value.size();
+      break;
+    }
+    default:
+      return false;
+  }
+  return true;
+}
+bool SerialProxySetModemPinsRequest::decode_varint(uint32_t field_id, ProtoVarInt value) {
+  switch (field_id) {
+    case 1:
+      this->instance = value.as_uint32();
+      break;
+    case 2:
+      this->rts = value.as_bool();
+      break;
+    case 3:
+      this->dtr = value.as_bool();
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+bool SerialProxyGetModemPinsRequest::decode_varint(uint32_t field_id, ProtoVarInt value) {
+  switch (field_id) {
+    case 1:
+      this->instance = value.as_uint32();
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+void SerialProxyGetModemPinsResponse::encode(ProtoWriteBuffer buffer) const {
+  buffer.encode_uint32(1, this->instance);
+  buffer.encode_bool(2, this->rts);
+  buffer.encode_bool(3, this->dtr);
+}
+void SerialProxyGetModemPinsResponse::calculate_size(ProtoSize &size) const {
+  size.add_uint32(1, this->instance);
+  size.add_bool(1, this->rts);
+  size.add_bool(1, this->dtr);
+}
+bool SerialProxyFlushRequest::decode_varint(uint32_t field_id, ProtoVarInt value) {
+  switch (field_id) {
+    case 1:
+      this->instance = value.as_uint32();
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+#endif
 
 }  // namespace esphome::api

esphome/components/api/api_pb2.h

@@ -311,6 +311,13 @@ enum ZWaveProxyRequestType : uint32_t {
   ZWAVE_PROXY_REQUEST_TYPE_HOME_ID_CHANGE = 2,
 };
 #endif
+#ifdef USE_SERIAL_PROXY
+enum SerialProxyParity : uint32_t {
+  SERIAL_PROXY_PARITY_NONE = 0,
+  SERIAL_PROXY_PARITY_EVEN = 1,
+  SERIAL_PROXY_PARITY_ODD = 2,
+};
+#endif
 
 }  // namespace enums
 
@@ -474,7 +481,7 @@ class DeviceInfo final : public ProtoMessage {
 class DeviceInfoResponse final : public ProtoMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 10;
-  static constexpr uint8_t ESTIMATED_SIZE = 255;
+  static constexpr uint16_t ESTIMATED_SIZE = 260;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "device_info_response"; }
 #endif
@@ -526,6 +533,9 @@ class DeviceInfoResponse final : public ProtoMessage {
 #endif
 #ifdef USE_ZWAVE_PROXY
   uint32_t zwave_home_id{0};
+#endif
+#ifdef USE_SERIAL_PROXY
+  uint32_t serial_proxy_count{0};
 #endif
   void encode(ProtoWriteBuffer buffer) const override;
   void calculate_size(ProtoSize &size) const override;
@@ -3025,5 +3035,132 @@ class InfraredRFReceiveEvent final : public ProtoMessage {
  protected:
 };
 #endif
+#ifdef USE_SERIAL_PROXY
+class SerialProxyConfigureRequest final : public ProtoDecodableMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 138;
+  static constexpr uint8_t ESTIMATED_SIZE = 20;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "serial_proxy_configure_request"; }
+#endif
+  uint32_t instance{0};
+  uint32_t baudrate{0};
+  bool flow_control{false};
+  enums::SerialProxyParity parity{};
+  uint32_t stop_bits{0};
+  uint32_t data_size{0};
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *dump_to(DumpBuffer &out) const override;
+#endif
+
+ protected:
+  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+};
+class SerialProxyDataReceived final : public ProtoMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 139;
+  static constexpr uint8_t ESTIMATED_SIZE = 23;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "serial_proxy_data_received"; }
+#endif
+  uint32_t instance{0};
+  const uint8_t *data_ptr_{nullptr};
+  size_t data_len_{0};
+  void set_data(const uint8_t *data, size_t len) {
+    this->data_ptr_ = data;
+    this->data_len_ = len;
+  }
+  void encode(ProtoWriteBuffer buffer) const override;
+  void calculate_size(ProtoSize &size) const override;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *dump_to(DumpBuffer &out) const override;
+#endif
+
+ protected:
+};
+class SerialProxyWriteRequest final : public ProtoDecodableMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 140;
+  static constexpr uint8_t ESTIMATED_SIZE = 23;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "serial_proxy_write_request"; }
+#endif
+  uint32_t instance{0};
+  const uint8_t *data{nullptr};
+  uint16_t data_len{0};
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *dump_to(DumpBuffer &out) const override;
+#endif
+
+ protected:
+  bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
+  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+};
+class SerialProxySetModemPinsRequest final : public ProtoDecodableMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 141;
+  static constexpr uint8_t ESTIMATED_SIZE = 8;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "serial_proxy_set_modem_pins_request"; }
+#endif
+  uint32_t instance{0};
+  bool rts{false};
+  bool dtr{false};
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *dump_to(DumpBuffer &out) const override;
+#endif
+
+ protected:
+  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+};
+class SerialProxyGetModemPinsRequest final : public ProtoDecodableMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 142;
+  static constexpr uint8_t ESTIMATED_SIZE = 4;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "serial_proxy_get_modem_pins_request"; }
+#endif
+  uint32_t instance{0};
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *dump_to(DumpBuffer &out) const override;
+#endif
+
+ protected:
+  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+};
+class SerialProxyGetModemPinsResponse final : public ProtoMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 143;
+  static constexpr uint8_t ESTIMATED_SIZE = 8;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "serial_proxy_get_modem_pins_response"; }
+#endif
+  uint32_t instance{0};
+  bool rts{false};
+  bool dtr{false};
+  void encode(ProtoWriteBuffer buffer) const override;
+  void calculate_size(ProtoSize &size) const override;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *dump_to(DumpBuffer &out) const override;
+#endif
+
+ protected:
+};
+class SerialProxyFlushRequest final : public ProtoDecodableMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 144;
+  static constexpr uint8_t ESTIMATED_SIZE = 4;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "serial_proxy_flush_request"; }
+#endif
+  uint32_t instance{0};
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *dump_to(DumpBuffer &out) const override;
+#endif
+
+ protected:
+  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+};
+#endif
 
 }  // namespace esphome::api

esphome/components/api/api_pb2_dump.cpp

@@ -736,6 +736,20 @@ template<> const char *proto_enum_to_string<enums::ZWaveProxyRequestType>(enums:
   }
 }
 #endif
+#ifdef USE_SERIAL_PROXY
+template<> const char *proto_enum_to_string<enums::SerialProxyParity>(enums::SerialProxyParity value) {
+  switch (value) {
+    case enums::SERIAL_PROXY_PARITY_NONE:
+      return "SERIAL_PROXY_PARITY_NONE";
+    case enums::SERIAL_PROXY_PARITY_EVEN:
+      return "SERIAL_PROXY_PARITY_EVEN";
+    case enums::SERIAL_PROXY_PARITY_ODD:
+      return "SERIAL_PROXY_PARITY_ODD";
+    default:
+      return "UNKNOWN";
+  }
+}
+#endif
 
 const char *HelloRequest::dump_to(DumpBuffer &out) const {
   MessageDumpHelper helper(out, "HelloRequest");
@@ -845,6 +859,9 @@ const char *DeviceInfoResponse::dump_to(DumpBuffer &out) const {
 #endif
 #ifdef USE_ZWAVE_PROXY
   dump_field(out, "zwave_home_id", this->zwave_home_id);
+#endif
+#ifdef USE_SERIAL_PROXY
+  dump_field(out, "serial_proxy_count", this->serial_proxy_count);
 #endif
   return out.c_str();
 }
@@ -2469,6 +2486,54 @@ const char *InfraredRFReceiveEvent::dump_to(DumpBuffer &out) const {
   return out.c_str();
 }
 #endif
+#ifdef USE_SERIAL_PROXY
+const char *SerialProxyConfigureRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyConfigureRequest");
+  dump_field(out, "instance", this->instance);
+  dump_field(out, "baudrate", this->baudrate);
+  dump_field(out, "flow_control", this->flow_control);
+  dump_field(out, "parity", static_cast<enums::SerialProxyParity>(this->parity));
+  dump_field(out, "stop_bits", this->stop_bits);
+  dump_field(out, "data_size", this->data_size);
+  return out.c_str();
+}
+const char *SerialProxyDataReceived::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyDataReceived");
+  dump_field(out, "instance", this->instance);
+  dump_bytes_field(out, "data", this->data_ptr_, this->data_len_);
+  return out.c_str();
+}
+const char *SerialProxyWriteRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyWriteRequest");
+  dump_field(out, "instance", this->instance);
+  dump_bytes_field(out, "data", this->data, this->data_len);
+  return out.c_str();
+}
+const char *SerialProxySetModemPinsRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxySetModemPinsRequest");
+  dump_field(out, "instance", this->instance);
+  dump_field(out, "rts", this->rts);
+  dump_field(out, "dtr", this->dtr);
+  return out.c_str();
+}
+const char *SerialProxyGetModemPinsRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyGetModemPinsRequest");
+  dump_field(out, "instance", this->instance);
+  return out.c_str();
+}
+const char *SerialProxyGetModemPinsResponse::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyGetModemPinsResponse");
+  dump_field(out, "instance", this->instance);
+  dump_field(out, "rts", this->rts);
+  dump_field(out, "dtr", this->dtr);
+  return out.c_str();
+}
+const char *SerialProxyFlushRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyFlushRequest");
+  dump_field(out, "instance", this->instance);
+  return out.c_str();
+}
+#endif
 
 }  // namespace esphome::api
 

esphome/components/api/api_pb2_service.cpp

@@ -634,6 +634,61 @@ void APIServerConnectionBase::read_message(uint32_t msg_size, uint32_t msg_type,
       this->on_infrared_rf_transmit_raw_timings_request(msg);
       break;
     }
+#endif
+#ifdef USE_SERIAL_PROXY
+    case SerialProxyConfigureRequest::MESSAGE_TYPE: {
+      SerialProxyConfigureRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_serial_proxy_configure_request"), msg);
+#endif
+      this->on_serial_proxy_configure_request(msg);
+      break;
+    }
+#endif
+#ifdef USE_SERIAL_PROXY
+    case SerialProxyWriteRequest::MESSAGE_TYPE: {
+      SerialProxyWriteRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_serial_proxy_write_request"), msg);
+#endif
+      this->on_serial_proxy_write_request(msg);
+      break;
+    }
+#endif
+#ifdef USE_SERIAL_PROXY
+    case SerialProxySetModemPinsRequest::MESSAGE_TYPE: {
+      SerialProxySetModemPinsRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_serial_proxy_set_modem_pins_request"), msg);
+#endif
+      this->on_serial_proxy_set_modem_pins_request(msg);
+      break;
+    }
+#endif
+#ifdef USE_SERIAL_PROXY
+    case SerialProxyGetModemPinsRequest::MESSAGE_TYPE: {
+      SerialProxyGetModemPinsRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_serial_proxy_get_modem_pins_request"), msg);
+#endif
+      this->on_serial_proxy_get_modem_pins_request(msg);
+      break;
+    }
+#endif
+#ifdef USE_SERIAL_PROXY
+    case SerialProxyFlushRequest::MESSAGE_TYPE: {
+      SerialProxyFlushRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_serial_proxy_flush_request"), msg);
+#endif
+      this->on_serial_proxy_flush_request(msg);
+      break;
+    }
 #endif
     default:
       break;

esphome/components/api/api_pb2_service.h

@@ -224,6 +224,23 @@ class APIServerConnectionBase : public ProtoService {
   virtual void on_infrared_rf_transmit_raw_timings_request(const InfraredRFTransmitRawTimingsRequest &value){};
 #endif
 
+#ifdef USE_SERIAL_PROXY
+  virtual void on_serial_proxy_configure_request(const SerialProxyConfigureRequest &value){};
+#endif
+
+#ifdef USE_SERIAL_PROXY
+  virtual void on_serial_proxy_write_request(const SerialProxyWriteRequest &value){};
+#endif
+#ifdef USE_SERIAL_PROXY
+  virtual void on_serial_proxy_set_modem_pins_request(const SerialProxySetModemPinsRequest &value){};
+#endif
+#ifdef USE_SERIAL_PROXY
+  virtual void on_serial_proxy_get_modem_pins_request(const SerialProxyGetModemPinsRequest &value){};
+#endif
+
+#ifdef USE_SERIAL_PROXY
+  virtual void on_serial_proxy_flush_request(const SerialProxyFlushRequest &value){};
+#endif
  protected:
   void read_message(uint32_t msg_size, uint32_t msg_type, const uint8_t *msg_data) override;
 };

esphome/components/api/api_server.cpp

@@ -370,6 +370,17 @@ void APIServer::send_infrared_rf_receive_event([[maybe_unused]] uint32_t device_
 }
 #endif
 
+#ifdef USE_SERIAL_PROXY
+void APIServer::send_serial_proxy_data(uint32_t instance, const uint8_t *data, size_t len) {
+  SerialProxyDataReceived msg{};
+  msg.instance = instance;
+  msg.set_data(data, len);
+
+  for (auto &c : this->clients_)
+    c->send_serial_proxy_data(msg);
+}
+#endif
+
 #ifdef USE_ALARM_CONTROL_PANEL
 API_DISPATCH_UPDATE(alarm_control_panel::AlarmControlPanel, alarm_control_panel)
 #endif

esphome/components/api/api_server.h

@@ -189,6 +189,10 @@ class APIServer : public Component,
   void send_infrared_rf_receive_event(uint32_t device_id, uint32_t key, const std::vector<int32_t> *timings);
 #endif
 
+#ifdef USE_SERIAL_PROXY
+  void send_serial_proxy_data(uint32_t instance, const uint8_t *data, size_t len);
+#endif
+
   bool is_connected(bool state_subscription_only = false) const;
 
 #ifdef USE_API_HOMEASSISTANT_STATES

esphome/components/api/proto.cpp

@@ -133,7 +133,7 @@ void ProtoDecodableMessage::decode(const uint8_t *buffer, size_t length) {
         break;
       }
       default:
-        ESP_LOGV(TAG, "Invalid field type %u at offset %ld", field_type, (long) (ptr - buffer));
+        ESP_LOGV(TAG, "Invalid field type %" PRIu32 " at offset %ld", field_type, (long) (ptr - buffer));
         return;
     }
   }

esphome/components/api/proto.h

@@ -57,6 +57,16 @@ inline uint16_t count_packed_varints(const uint8_t *data, size_t len) {
   return count;
 }
 
+/// Encode a varint directly into a pre-allocated buffer.
+/// Caller must ensure buffer has space (use ProtoSize::varint() to calculate).
+inline void encode_varint_to_buffer(uint32_t val, uint8_t *buffer) {
+  while (val > 0x7F) {
+    *buffer++ = static_cast<uint8_t>(val | 0x80);
+    val >>= 7;
+  }
+  *buffer = static_cast<uint8_t>(val);
+}
+
 /*
  * StringRef Ownership Model for API Protocol Messages
  * ===================================================
@@ -93,17 +103,17 @@ class ProtoVarInt {
   ProtoVarInt() : value_(0) {}
   explicit ProtoVarInt(uint64_t value) : value_(value) {}
 
+  /// Parse a varint from buffer. consumed must be a valid pointer (not null).
   static optional<ProtoVarInt> parse(const uint8_t *buffer, uint32_t len, uint32_t *consumed) {
-    if (len == 0) {
-      if (consumed != nullptr)
-        *consumed = 0;
+#ifdef ESPHOME_DEBUG_API
+    assert(consumed != nullptr);
+#endif
+    if (len == 0)
       return {};
-    }
 
     // Most common case: single-byte varint (values 0-127)
     if ((buffer[0] & 0x80) == 0) {
-      if (consumed != nullptr)
-        *consumed = 1;
+      *consumed = 1;
       return ProtoVarInt(buffer[0]);
     }
 
@@ -122,14 +132,11 @@ class ProtoVarInt {
       result |= uint64_t(val & 0x7F) << uint64_t(bitpos);
       bitpos += 7;
       if ((val & 0x80) == 0) {
-        if (consumed != nullptr)
-          *consumed = i + 1;
+        *consumed = i + 1;
         return ProtoVarInt(result);
       }
     }
 
-    if (consumed != nullptr)
-      *consumed = 0;
     return {};  // Incomplete or invalid varint
   }
 
@@ -153,50 +160,6 @@ class ProtoVarInt {
     // with ZigZag encoding
     return decode_zigzag64(this->value_);
   }
-  /**
-   * Encode the varint value to a pre-allocated buffer without bounds checking.
-   *
-   * @param buffer The pre-allocated buffer to write the encoded varint to
-   * @param len The size of the buffer in bytes
-   *
-   * @note The caller is responsible for ensuring the buffer is large enough
-   *       to hold the encoded value. Use ProtoSize::varint() to calculate
-   *       the exact size needed before calling this method.
-   * @note No bounds checking is performed for performance reasons.
-   */
-  void encode_to_buffer_unchecked(uint8_t *buffer, size_t len) {
-    uint64_t val = this->value_;
-    if (val <= 0x7F) {
-      buffer[0] = val;
-      return;
-    }
-    size_t i = 0;
-    while (val && i < len) {
-      uint8_t temp = val & 0x7F;
-      val >>= 7;
-      if (val) {
-        buffer[i++] = temp | 0x80;
-      } else {
-        buffer[i++] = temp;
-      }
-    }
-  }
-  void encode(std::vector<uint8_t> &out) {
-    uint64_t val = this->value_;
-    if (val <= 0x7F) {
-      out.push_back(val);
-      return;
-    }
-    while (val) {
-      uint8_t temp = val & 0x7F;
-      val >>= 7;
-      if (val) {
-        out.push_back(temp | 0x80);
-      } else {
-        out.push_back(temp);
-      }
-    }
-  }
 
  protected:
   uint64_t value_;
@@ -256,8 +219,20 @@ class ProtoWriteBuffer {
  public:
   ProtoWriteBuffer(std::vector<uint8_t> *buffer) : buffer_(buffer) {}
   void write(uint8_t value) { this->buffer_->push_back(value); }
-  void encode_varint_raw(ProtoVarInt value) { value.encode(*this->buffer_); }
-  void encode_varint_raw(uint32_t value) { this->encode_varint_raw(ProtoVarInt(value)); }
+  void encode_varint_raw(uint32_t value) {
+    while (value > 0x7F) {
+      this->buffer_->push_back(static_cast<uint8_t>(value | 0x80));
+      value >>= 7;
+    }
+    this->buffer_->push_back(static_cast<uint8_t>(value));
+  }
+  void encode_varint_raw_64(uint64_t value) {
+    while (value > 0x7F) {
+      this->buffer_->push_back(static_cast<uint8_t>(value | 0x80));
+      value >>= 7;
+    }
+    this->buffer_->push_back(static_cast<uint8_t>(value));
+  }
   /**
    * Encode a field key (tag/wire type combination).
    *
@@ -307,13 +282,13 @@ class ProtoWriteBuffer {
     if (value == 0 && !force)
       return;
     this->encode_field_raw(field_id, 0);  // type 0: Varint - uint64
-    this->encode_varint_raw(ProtoVarInt(value));
+    this->encode_varint_raw_64(value);
   }
   void encode_bool(uint32_t field_id, bool value, bool force = false) {
     if (!value && !force)
       return;
     this->encode_field_raw(field_id, 0);  // type 0: Varint - bool
-    this->write(0x01);
+    this->buffer_->push_back(value ? 0x01 : 0x00);
   }
   void encode_fixed32(uint32_t field_id, uint32_t value, bool force = false) {
     if (value == 0 && !force)
@@ -938,13 +913,15 @@ inline void ProtoWriteBuffer::encode_message(uint32_t field_id, const ProtoMessa
   this->buffer_->resize(this->buffer_->size() + varint_length_bytes);
 
   // Write the length varint directly
-  ProtoVarInt(msg_length_bytes).encode_to_buffer_unchecked(this->buffer_->data() + begin, varint_length_bytes);
+  encode_varint_to_buffer(msg_length_bytes, this->buffer_->data() + begin);
 
   // Now encode the message content - it will append to the buffer
   value.encode(*this);
 
+#ifdef ESPHOME_DEBUG_API
   // Verify that the encoded size matches what we calculated
   assert(this->buffer_->size() == begin + varint_length_bytes + msg_length_bytes);
+#endif
 }
 
 // Implementation of decode_to_message - must be after ProtoDecodableMessage is defined

esphome/components/bl0942/bl0942.h

@@ -59,10 +59,10 @@ namespace bl0942 {
 //
 // Which makes BL0952_EREF = BL0942_PREF * 3600000 / 419430.4
 
-static const float BL0942_PREF = 596;              // taken from tasmota
-static const float BL0942_UREF = 15873.35944299;   // should be 73989/1.218
-static const float BL0942_IREF = 251213.46469622;  // 305978/1.218
-static const float BL0942_EREF = 3304.61127328;    // Measured
+static const float BL0942_PREF = 623.0270705;  // calculated using UREF and IREF
+static const float BL0942_UREF = 15883.34116;  // calculated for (390k x 5 / 510R) voltage divider
+static const float BL0942_IREF = 251065.6814;  // calculated for 1mR shunt
+static const float BL0942_EREF = 5347.484240;  // calculated using UREF and IREF
 
 struct DataPacket {
   uint8_t frame_header;
@@ -86,11 +86,11 @@ enum LineFrequency : uint8_t {
 
 class BL0942 : public PollingComponent, public uart::UARTDevice {
  public:
-  void set_voltage_sensor(sensor::Sensor *voltage_sensor) { voltage_sensor_ = voltage_sensor; }
-  void set_current_sensor(sensor::Sensor *current_sensor) { current_sensor_ = current_sensor; }
-  void set_power_sensor(sensor::Sensor *power_sensor) { power_sensor_ = power_sensor; }
-  void set_energy_sensor(sensor::Sensor *energy_sensor) { energy_sensor_ = energy_sensor; }
-  void set_frequency_sensor(sensor::Sensor *frequency_sensor) { frequency_sensor_ = frequency_sensor; }
+  void set_voltage_sensor(sensor::Sensor *voltage_sensor) { this->voltage_sensor_ = voltage_sensor; }
+  void set_current_sensor(sensor::Sensor *current_sensor) { this->current_sensor_ = current_sensor; }
+  void set_power_sensor(sensor::Sensor *power_sensor) { this->power_sensor_ = power_sensor; }
+  void set_energy_sensor(sensor::Sensor *energy_sensor) { this->energy_sensor_ = energy_sensor; }
+  void set_frequency_sensor(sensor::Sensor *frequency_sensor) { this->frequency_sensor_ = frequency_sensor; }
   void set_line_freq(LineFrequency freq) { this->line_freq_ = freq; }
   void set_address(uint8_t address) { this->address_ = address; }
   void set_reset(bool reset) { this->reset_ = reset; }

esphome/components/cover/__init__.py

@@ -11,6 +11,7 @@ from esphome.const import (
     CONF_ICON,
     CONF_ID,
     CONF_MQTT_ID,
+    CONF_MQTT_JSON_STATE_PAYLOAD,
     CONF_ON_IDLE,
     CONF_ON_OPEN,
     CONF_POSITION,
@@ -119,6 +120,9 @@ _COVER_SCHEMA = (
     .extend(
         {
             cv.OnlyWith(CONF_MQTT_ID, "mqtt"): cv.declare_id(mqtt.MQTTCoverComponent),
+            cv.Optional(CONF_MQTT_JSON_STATE_PAYLOAD): cv.All(
+                cv.requires_component("mqtt"), cv.boolean
+            ),
             cv.Optional(CONF_DEVICE_CLASS): cv.one_of(*DEVICE_CLASSES, lower=True),
             cv.Optional(CONF_POSITION_COMMAND_TOPIC): cv.All(
                 cv.requires_component("mqtt"), cv.subscribe_topic
@@ -148,6 +152,22 @@ _COVER_SCHEMA = (
 _COVER_SCHEMA.add_extra(entity_duplicate_validator("cover"))
 
 
+def _validate_mqtt_state_topics(config):
+    if config.get(CONF_MQTT_JSON_STATE_PAYLOAD):
+        if CONF_POSITION_STATE_TOPIC in config:
+            raise cv.Invalid(
+                f"'{CONF_POSITION_STATE_TOPIC}' cannot be used with '{CONF_MQTT_JSON_STATE_PAYLOAD}: true'"
+            )
+        if CONF_TILT_STATE_TOPIC in config:
+            raise cv.Invalid(
+                f"'{CONF_TILT_STATE_TOPIC}' cannot be used with '{CONF_MQTT_JSON_STATE_PAYLOAD}: true'"
+            )
+    return config
+
+
+_COVER_SCHEMA.add_extra(_validate_mqtt_state_topics)
+
+
 def cover_schema(
     class_: MockObjClass,
     *,
@@ -195,6 +215,9 @@ async def setup_cover_core_(var, config):
             position_command_topic := config.get(CONF_POSITION_COMMAND_TOPIC)
         ) is not None:
             cg.add(mqtt_.set_custom_position_command_topic(position_command_topic))
+        if config.get(CONF_MQTT_JSON_STATE_PAYLOAD):
+            cg.add_define("USE_MQTT_COVER_JSON")
+            cg.add(mqtt_.set_use_json_format(True))
         if (tilt_state_topic := config.get(CONF_TILT_STATE_TOPIC)) is not None:
             cg.add(mqtt_.set_custom_tilt_state_topic(tilt_state_topic))
         if (tilt_command_topic := config.get(CONF_TILT_COMMAND_TOPIC)) is not None:

esphome/components/esp32/preferences.cpp

@@ -124,14 +124,11 @@ class ESP32Preferences : public ESPPreferences {
       return true;
 
     ESP_LOGV(TAG, "Saving %zu items...", s_pending_save.size());
-    // goal try write all pending saves even if one fails
     int cached = 0, written = 0, failed = 0;
     esp_err_t last_err = ESP_OK;
     uint32_t last_key = 0;
 
-    // go through vector from back to front (makes erase easier/more efficient)
-    for (ssize_t i = s_pending_save.size() - 1; i >= 0; i--) {
-      const auto &save = s_pending_save[i];
+    for (const auto &save : s_pending_save) {
       char key_str[KEY_BUFFER_SIZE];
       snprintf(key_str, sizeof(key_str), "%" PRIu32, save.key);
       ESP_LOGVV(TAG, "Checking if NVS data %s has changed", key_str);
@@ -150,8 +147,9 @@ class ESP32Preferences : public ESPPreferences {
         ESP_LOGV(TAG, "NVS data not changed skipping %" PRIu32 "  len=%zu", save.key, save.len);
         cached++;
       }
-      s_pending_save.erase(s_pending_save.begin() + i);
     }
+    s_pending_save.clear();
+
     ESP_LOGD(TAG, "Writing %d items: %d cached, %d written, %d failed", cached + written + failed, cached, written,
              failed);
     if (failed > 0) {

esphome/components/esp32_improv/esp32_improv_component.cpp

@@ -338,8 +338,8 @@ void ESP32ImprovComponent::process_incoming_data_() {
           return;
         }
         wifi::WiFiAP sta{};
-        sta.set_ssid(command.ssid);
-        sta.set_password(command.password);
+        sta.set_ssid(command.ssid.c_str());
+        sta.set_password(command.password.c_str());
         this->connecting_sta_ = sta;
 
         wifi::global_wifi_component->set_sta(sta);

esphome/components/esp8266/preferences.cpp

@@ -33,6 +33,10 @@ static constexpr uint32_t MAX_PREFERENCE_WORDS = 255;
 
 #define ESP_RTC_USER_MEM ((uint32_t *) ESP_RTC_USER_MEM_START)
 
+// Flash storage size depends on esp8266 -> restore_from_flash YAML option (default: false).
+// When enabled (USE_ESP8266_PREFERENCES_FLASH), all preferences default to flash and need
+// 128 words (512 bytes). When disabled, only explicit flash prefs use this storage so
+// 64 words (256 bytes) suffices since most preferences go to RTC memory instead.
 #ifdef USE_ESP8266_PREFERENCES_FLASH
 static constexpr uint32_t ESP8266_FLASH_STORAGE_SIZE = 128;
 #else
@@ -127,9 +131,11 @@ static bool load_from_rtc(size_t offset, uint32_t *data, size_t len) {
   return true;
 }
 
-// Stack buffer size - 16 words total: up to 15 words of preference data + 1 word CRC (60 bytes of preference data)
-// This handles virtually all real-world preferences without heap allocation
-static constexpr size_t PREF_BUFFER_WORDS = 16;
+// Maximum buffer for any single preference - bounded by storage sizes.
+// Flash prefs: bounded by ESP8266_FLASH_STORAGE_SIZE (128 or 64 words).
+// RTC prefs: bounded by RTC_NORMAL_REGION_WORDS (96) - a single pref can't span both RTC regions.
+static constexpr size_t PREF_MAX_BUFFER_WORDS =
+    ESP8266_FLASH_STORAGE_SIZE > RTC_NORMAL_REGION_WORDS ? ESP8266_FLASH_STORAGE_SIZE : RTC_NORMAL_REGION_WORDS;
 
 class ESP8266PreferenceBackend : public ESPPreferenceBackend {
  public:
@@ -141,15 +147,13 @@ class ESP8266PreferenceBackend : public ESPPreferenceBackend {
   bool save(const uint8_t *data, size_t len) override {
     if (bytes_to_words(len) != this->length_words)
       return false;
-
     const size_t buffer_size = static_cast<size_t>(this->length_words) + 1;
-    SmallBufferWithHeapFallback<PREF_BUFFER_WORDS, uint32_t> buffer_alloc(buffer_size);
-    uint32_t *buffer = buffer_alloc.get();
+    if (buffer_size > PREF_MAX_BUFFER_WORDS)
+      return false;
+    uint32_t buffer[PREF_MAX_BUFFER_WORDS];
     memset(buffer, 0, buffer_size * sizeof(uint32_t));
-
     memcpy(buffer, data, len);
     buffer[this->length_words] = calculate_crc(buffer, buffer + this->length_words, this->type);
-
     return this->in_flash ? save_to_flash(this->offset, buffer, buffer_size)
                           : save_to_rtc(this->offset, buffer, buffer_size);
   }
@@ -157,19 +161,16 @@ class ESP8266PreferenceBackend : public ESPPreferenceBackend {
   bool load(uint8_t *data, size_t len) override {
     if (bytes_to_words(len) != this->length_words)
       return false;
-
     const size_t buffer_size = static_cast<size_t>(this->length_words) + 1;
-    SmallBufferWithHeapFallback<PREF_BUFFER_WORDS, uint32_t> buffer_alloc(buffer_size);
-    uint32_t *buffer = buffer_alloc.get();
-
+    if (buffer_size > PREF_MAX_BUFFER_WORDS)
+      return false;
+    uint32_t buffer[PREF_MAX_BUFFER_WORDS];
     bool ret = this->in_flash ? load_from_flash(this->offset, buffer, buffer_size)
                               : load_from_rtc(this->offset, buffer, buffer_size);
     if (!ret)
       return false;
-
     if (buffer[this->length_words] != calculate_crc(buffer, buffer + this->length_words, this->type))
       return false;
-
     memcpy(data, buffer, len);
     return true;
   }

esphome/components/improv_serial/improv_serial_component.cpp

@@ -235,8 +235,8 @@ bool ImprovSerialComponent::parse_improv_payload_(improv::ImprovCommand &command
   switch (command.command) {
     case improv::WIFI_SETTINGS: {
       wifi::WiFiAP sta{};
-      sta.set_ssid(command.ssid);
-      sta.set_password(command.password);
+      sta.set_ssid(command.ssid.c_str());
+      sta.set_password(command.password.c_str());
       this->connecting_sta_ = sta;
 
       wifi::global_wifi_component->set_sta(sta);
@@ -267,16 +267,26 @@ bool ImprovSerialComponent::parse_improv_payload_(improv::ImprovCommand &command
       for (auto &scan : results) {
         if (scan.get_is_hidden())
           continue;
-        const std::string &ssid = scan.get_ssid();
-        if (std::find(networks.begin(), networks.end(), ssid) != networks.end())
+        const char *ssid_cstr = scan.get_ssid().c_str();
+        // Check if we've already sent this SSID
+        bool duplicate = false;
+        for (const auto &seen : networks) {
+          if (strcmp(seen.c_str(), ssid_cstr) == 0) {
+            duplicate = true;
+            break;
+          }
+        }
+        if (duplicate)
           continue;
+        // Only allocate std::string after confirming it's not a duplicate
+        std::string ssid(ssid_cstr);
         // Send each ssid separately to avoid overflowing the buffer
         char rssi_buf[5];  // int8_t: -128 to 127, max 4 chars + null
         *int8_to_str(rssi_buf, scan.get_rssi()) = '\0';
         std::vector<uint8_t> data =
             improv::build_rpc_response(improv::GET_WIFI_NETWORKS, {ssid, rssi_buf, YESNO(scan.get_with_auth())}, false);
         this->send_response_(data);
-        networks.push_back(ssid);
+        networks.push_back(std::move(ssid));
       }
       // Send empty response to signify the end of the list.
       std::vector<uint8_t> data =

esphome/components/libretiny/preferences.cpp

@@ -114,14 +114,11 @@ class LibreTinyPreferences : public ESPPreferences {
       return true;
 
     ESP_LOGV(TAG, "Saving %zu items...", s_pending_save.size());
-    // goal try write all pending saves even if one fails
     int cached = 0, written = 0, failed = 0;
     fdb_err_t last_err = FDB_NO_ERR;
     uint32_t last_key = 0;
 
-    // go through vector from back to front (makes erase easier/more efficient)
-    for (ssize_t i = s_pending_save.size() - 1; i >= 0; i--) {
-      const auto &save = s_pending_save[i];
+    for (const auto &save : s_pending_save) {
       char key_str[KEY_BUFFER_SIZE];
       snprintf(key_str, sizeof(key_str), "%" PRIu32, save.key);
       ESP_LOGVV(TAG, "Checking if FDB data %s has changed", key_str);
@@ -141,8 +138,9 @@ class LibreTinyPreferences : public ESPPreferences {
         ESP_LOGD(TAG, "FDB data not changed; skipping %" PRIu32 "  len=%zu", save.key, save.len);
         cached++;
       }
-      s_pending_save.erase(s_pending_save.begin() + i);
     }
+    s_pending_save.clear();
+
     ESP_LOGD(TAG, "Writing %d items: %d cached, %d written, %d failed", cached + written + failed, cached, written,
              failed);
     if (failed > 0) {

esphome/components/light/light_call.cpp

@@ -270,22 +270,23 @@ LightColorValues LightCall::validate_() {
   if (this->has_state())
     v.set_state(this->state_);
 
-#define VALIDATE_AND_APPLY(field, setter, name_str, ...) \
+    // clamp_and_log_if_invalid already clamps in-place, so assign directly
+    // to avoid redundant clamp code from the setter being inlined.
+#define VALIDATE_AND_APPLY(field, name_str, ...) \
   if (this->has_##field()) { \
     clamp_and_log_if_invalid(name, this->field##_, LOG_STR(name_str), ##__VA_ARGS__); \
-    v.setter(this->field##_); \
+    v.field##_ = this->field##_; \
   }
 
-  VALIDATE_AND_APPLY(brightness, set_brightness, "Brightness")
-  VALIDATE_AND_APPLY(color_brightness, set_color_brightness, "Color brightness")
-  VALIDATE_AND_APPLY(red, set_red, "Red")
-  VALIDATE_AND_APPLY(green, set_green, "Green")
-  VALIDATE_AND_APPLY(blue, set_blue, "Blue")
-  VALIDATE_AND_APPLY(white, set_white, "White")
-  VALIDATE_AND_APPLY(cold_white, set_cold_white, "Cold white")
-  VALIDATE_AND_APPLY(warm_white, set_warm_white, "Warm white")
-  VALIDATE_AND_APPLY(color_temperature, set_color_temperature, "Color temperature", traits.get_min_mireds(),
-                     traits.get_max_mireds())
+  VALIDATE_AND_APPLY(brightness, "Brightness")
+  VALIDATE_AND_APPLY(color_brightness, "Color brightness")
+  VALIDATE_AND_APPLY(red, "Red")
+  VALIDATE_AND_APPLY(green, "Green")
+  VALIDATE_AND_APPLY(blue, "Blue")
+  VALIDATE_AND_APPLY(white, "White")
+  VALIDATE_AND_APPLY(cold_white, "Cold white")
+  VALIDATE_AND_APPLY(warm_white, "Warm white")
+  VALIDATE_AND_APPLY(color_temperature, "Color temperature", traits.get_min_mireds(), traits.get_max_mireds())
 
 #undef VALIDATE_AND_APPLY
 

esphome/components/light/light_color_values.h

@@ -95,15 +95,18 @@ class LightColorValues {
    */
   void normalize_color() {
     if (this->color_mode_ & ColorCapability::RGB) {
-      float max_value = fmaxf(this->get_red(), fmaxf(this->get_green(), this->get_blue()));
+      float max_value = fmaxf(this->red_, fmaxf(this->green_, this->blue_));
+      // Assign directly to avoid redundant clamp in set_red/green/blue.
+      // Values are guaranteed in [0,1]: inputs are already clamped to [0,1],
+      // and dividing by max_value (the largest) keeps results in [0,1].
       if (max_value == 0.0f) {
-        this->set_red(1.0f);
-        this->set_green(1.0f);
-        this->set_blue(1.0f);
+        this->red_ = 1.0f;
+        this->green_ = 1.0f;
+        this->blue_ = 1.0f;
       } else {
-        this->set_red(this->get_red() / max_value);
-        this->set_green(this->get_green() / max_value);
-        this->set_blue(this->get_blue() / max_value);
+        this->red_ /= max_value;
+        this->green_ /= max_value;
+        this->blue_ /= max_value;
       }
     }
   }
@@ -276,6 +279,8 @@ class LightColorValues {
   /// Set the warm white property of these light color values. In range 0.0 to 1.0.
   void set_warm_white(float warm_white) { this->warm_white_ = clamp(warm_white, 0.0f, 1.0f); }
 
+  friend class LightCall;
+
  protected:
   float state_;  ///< ON / OFF, float for transition
   float brightness_;

esphome/components/logger/__init__.py

@@ -231,9 +231,16 @@ CONFIG_SCHEMA = cv.All(
                 bk72xx=768,
                 ln882x=768,
                 rtl87xx=768,
+                nrf52=768,
             ): cv.All(
                 cv.only_on(
-                    [PLATFORM_ESP32, PLATFORM_BK72XX, PLATFORM_LN882X, PLATFORM_RTL87XX]
+                    [
+                        PLATFORM_ESP32,
+                        PLATFORM_BK72XX,
+                        PLATFORM_LN882X,
+                        PLATFORM_RTL87XX,
+                        PLATFORM_NRF52,
+                    ]
                 ),
                 cv.validate_bytes,
                 cv.Any(
@@ -313,11 +320,13 @@ async def to_code(config):
     )
     if CORE.is_esp32:
         cg.add(log.create_pthread_key())
-    if CORE.is_esp32 or CORE.is_libretiny:
+    if CORE.is_esp32 or CORE.is_libretiny or CORE.is_nrf52:
         task_log_buffer_size = config[CONF_TASK_LOG_BUFFER_SIZE]
         if task_log_buffer_size > 0:
             cg.add_define("USE_ESPHOME_TASK_LOG_BUFFER")
             cg.add(log.init_log_buffer(task_log_buffer_size))
+            if CORE.using_zephyr:
+                zephyr_add_prj_conf("MPSC_PBUF", True)
     elif CORE.is_host:
         cg.add(log.create_pthread_key())
         cg.add_define("USE_ESPHOME_TASK_LOG_BUFFER")
@@ -417,6 +426,7 @@ async def to_code(config):
         pass
 
     if CORE.is_nrf52:
+        zephyr_add_prj_conf("THREAD_LOCAL_STORAGE", True)
         if config[CONF_HARDWARE_UART] == UART0:
             zephyr_add_overlay("""&uart0 { status = "okay";};""")
         if config[CONF_HARDWARE_UART] == UART1:

esphome/components/logger/log_buffer.h

@@ -0,0 +1,190 @@
+#pragma once
+
+#include "esphome/core/helpers.h"
+#include "esphome/core/log.h"
+
+namespace esphome::logger {
+
+// Maximum header size: 35 bytes fixed + 32 bytes tag + 16 bytes thread name = 83 bytes (45 byte safety margin)
+static constexpr uint16_t MAX_HEADER_SIZE = 128;
+
+// ANSI color code last digit (30-38 range, store only last digit to save RAM)
+static constexpr char LOG_LEVEL_COLOR_DIGIT[] = {
+    '\0',  // NONE
+    '1',   // ERROR (31 = red)
+    '3',   // WARNING (33 = yellow)
+    '2',   // INFO (32 = green)
+    '5',   // CONFIG (35 = magenta)
+    '6',   // DEBUG (36 = cyan)
+    '7',   // VERBOSE (37 = gray)
+    '8',   // VERY_VERBOSE (38 = white)
+};
+
+static constexpr char LOG_LEVEL_LETTER_CHARS[] = {
+    '\0',  // NONE
+    'E',   // ERROR
+    'W',   // WARNING
+    'I',   // INFO
+    'C',   // CONFIG
+    'D',   // DEBUG
+    'V',   // VERBOSE (VERY_VERBOSE uses two 'V's)
+};
+
+// Buffer wrapper for log formatting functions
+struct LogBuffer {
+  char *data;
+  uint16_t size;
+  uint16_t pos{0};
+  // Replaces the null terminator with a newline for console output.
+  // Must be called after notify_listeners_() since listeners need null-terminated strings.
+  // Console output uses length-based writes (buf.pos), so null terminator is not needed.
+  void terminate_with_newline() {
+    if (this->pos < this->size) {
+      this->data[this->pos++] = '\n';
+    } else if (this->size > 0) {
+      // Buffer was full - replace last char with newline to ensure it's visible
+      this->data[this->size - 1] = '\n';
+      this->pos = this->size;
+    }
+  }
+  void HOT write_header(uint8_t level, const char *tag, int line, const char *thread_name) {
+    // Early return if insufficient space - intentionally don't update pos to prevent partial writes
+    if (this->pos + MAX_HEADER_SIZE > this->size)
+      return;
+
+    char *p = this->current_();
+
+    // Write ANSI color
+    this->write_ansi_color_(p, level);
+
+    // Construct: [LEVEL][tag:line]
+    *p++ = '[';
+    if (level != 0) {
+      if (level >= 7) {
+        *p++ = 'V';  // VERY_VERBOSE = "VV"
+        *p++ = 'V';
+      } else {
+        *p++ = LOG_LEVEL_LETTER_CHARS[level];
+      }
+    }
+    *p++ = ']';
+    *p++ = '[';
+
+    // Copy tag
+    this->copy_string_(p, tag);
+
+    *p++ = ':';
+
+    // Format line number without modulo operations
+    if (line > 999) [[unlikely]] {
+      int thousands = line / 1000;
+      *p++ = '0' + thousands;
+      line -= thousands * 1000;
+    }
+    int hundreds = line / 100;
+    int remainder = line - hundreds * 100;
+    int tens = remainder / 10;
+    *p++ = '0' + hundreds;
+    *p++ = '0' + tens;
+    *p++ = '0' + (remainder - tens * 10);
+    *p++ = ']';
+
+#if defined(USE_ESP32) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR) || defined(USE_HOST)
+    // Write thread name with bold red color
+    if (thread_name != nullptr) {
+      this->write_ansi_color_(p, 1);  // Bold red for thread name
+      *p++ = '[';
+      this->copy_string_(p, thread_name);
+      *p++ = ']';
+      this->write_ansi_color_(p, level);  // Restore original color
+    }
+#endif
+
+    *p++ = ':';
+    *p++ = ' ';
+
+    this->pos = p - this->data;
+  }
+  void HOT format_body(const char *format, va_list args) {
+    this->format_vsnprintf_(format, args);
+    this->finalize_();
+  }
+#ifdef USE_STORE_LOG_STR_IN_FLASH
+  void HOT format_body_P(PGM_P format, va_list args) {
+    this->format_vsnprintf_P_(format, args);
+    this->finalize_();
+  }
+#endif
+  void write_body(const char *text, uint16_t text_length) {
+    this->write_(text, text_length);
+    this->finalize_();
+  }
+
+ private:
+  bool full_() const { return this->pos >= this->size; }
+  uint16_t remaining_() const { return this->size - this->pos; }
+  char *current_() { return this->data + this->pos; }
+  void write_(const char *value, uint16_t length) {
+    const uint16_t available = this->remaining_();
+    const uint16_t copy_len = (length < available) ? length : available;
+    if (copy_len > 0) {
+      memcpy(this->current_(), value, copy_len);
+      this->pos += copy_len;
+    }
+  }
+  void finalize_() {
+    // Write color reset sequence
+    static constexpr uint16_t RESET_COLOR_LEN = sizeof(ESPHOME_LOG_RESET_COLOR) - 1;
+    this->write_(ESPHOME_LOG_RESET_COLOR, RESET_COLOR_LEN);
+    // Null terminate
+    this->data[this->full_() ? this->size - 1 : this->pos] = '\0';
+  }
+  void strip_trailing_newlines_() {
+    while (this->pos > 0 && this->data[this->pos - 1] == '\n')
+      this->pos--;
+  }
+  void process_vsnprintf_result_(int ret) {
+    if (ret < 0)
+      return;
+    const uint16_t rem = this->remaining_();
+    this->pos += (ret >= rem) ? (rem - 1) : static_cast<uint16_t>(ret);
+    this->strip_trailing_newlines_();
+  }
+  void format_vsnprintf_(const char *format, va_list args) {
+    if (this->full_())
+      return;
+    this->process_vsnprintf_result_(vsnprintf(this->current_(), this->remaining_(), format, args));
+  }
+#ifdef USE_STORE_LOG_STR_IN_FLASH
+  void format_vsnprintf_P_(PGM_P format, va_list args) {
+    if (this->full_())
+      return;
+    this->process_vsnprintf_result_(vsnprintf_P(this->current_(), this->remaining_(), format, args));
+  }
+#endif
+  // Write ANSI color escape sequence to buffer, updates pointer in place
+  // Caller is responsible for ensuring buffer has sufficient space
+  void write_ansi_color_(char *&p, uint8_t level) {
+    if (level == 0)
+      return;
+    // Direct buffer fill: "\033[{bold};3{color}m" (7 bytes)
+    *p++ = '\033';
+    *p++ = '[';
+    *p++ = (level == 1) ? '1' : '0';  // Only ERROR is bold
+    *p++ = ';';
+    *p++ = '3';
+    *p++ = LOG_LEVEL_COLOR_DIGIT[level];
+    *p++ = 'm';
+  }
+  // Copy string without null terminator, updates pointer in place
+  // Caller is responsible for ensuring buffer has sufficient space
+  void copy_string_(char *&p, const char *str) {
+    const size_t len = strlen(str);
+    // NOLINTNEXTLINE(bugprone-not-null-terminated-result) - intentionally no null terminator, building string piece by
+    // piece
+    memcpy(p, str, len);
+    p += len;
+  }
+};
+
+}  // namespace esphome::logger

esphome/components/logger/logger.cpp

@@ -10,9 +10,9 @@ namespace esphome::logger {
 
 static const char *const TAG = "logger";
 
-#if defined(USE_ESP32) || defined(USE_HOST) || defined(USE_LIBRETINY)
-// Implementation for multi-threaded platforms (ESP32 with FreeRTOS, Host with pthreads, LibreTiny with FreeRTOS)
-// Main thread/task always uses direct buffer access for console output and callbacks
+#if defined(USE_ESP32) || defined(USE_HOST) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR)
+// Implementation for multi-threaded platforms (ESP32 with FreeRTOS, Host with pthreads, LibreTiny with FreeRTOS,
+// Zephyr) Main thread/task always uses direct buffer access for console output and callbacks
 //
 // For non-main threads/tasks:
 //  - WITH task log buffer: Prefer sending to ring buffer for async processing
@@ -31,6 +31,9 @@ void HOT Logger::log_vprintf_(uint8_t level, const char *tag, int line, const ch
   // Get task handle once - used for both main task check and passing to non-main thread handler
   TaskHandle_t current_task = xTaskGetCurrentTaskHandle();
   const bool is_main_task = (current_task == this->main_task_);
+#elif (USE_ZEPHYR)
+  k_tid_t current_task = k_current_get();
+  const bool is_main_task = (current_task == this->main_task_);
 #else  // USE_HOST
   const bool is_main_task = pthread_equal(pthread_self(), this->main_thread_);
 #endif
@@ -54,6 +57,9 @@ void HOT Logger::log_vprintf_(uint8_t level, const char *tag, int line, const ch
   // Host: pass a stack buffer for pthread_getname_np to write into.
 #if defined(USE_ESP32) || defined(USE_LIBRETINY)
   const char *thread_name = get_thread_name_(current_task);
+#elif defined(USE_ZEPHYR)
+  char thread_name_buf[MAX_POINTER_REPRESENTATION];
+  const char *thread_name = get_thread_name_(thread_name_buf, current_task);
 #else  // USE_HOST
   char thread_name_buf[THREAD_NAME_BUF_SIZE];
   const char *thread_name = this->get_thread_name_(thread_name_buf);
@@ -83,18 +89,21 @@ void Logger::log_vprintf_non_main_thread_(uint8_t level, const char *tag, int li
     // This is safe to call from any context including ISRs
     this->enable_loop_soon_any_context();
   }
-#endif  // USE_ESPHOME_TASK_LOG_BUFFER
-
+#endif
   // Emergency console logging for non-main threads when ring buffer is full or disabled
   // This is a fallback mechanism to ensure critical log messages are visible
   // Note: This may cause interleaved/corrupted console output if multiple threads
   // log simultaneously, but it's better than losing important messages entirely
 #ifdef USE_HOST
-  if (!message_sent) {
+  if (!message_sent)
+#else
+  if (!message_sent && this->baud_rate_ > 0)  // If logging is enabled, write to console
+#endif
+  {
+#ifdef USE_HOST
     // Host always has console output - no baud_rate check needed
     static const size_t MAX_CONSOLE_LOG_MSG_SIZE = 512;
 #else
-  if (!message_sent && this->baud_rate_ > 0) {  // If logging is enabled, write to console
     // Maximum size for console log messages (includes null terminator)
     static const size_t MAX_CONSOLE_LOG_MSG_SIZE = 144;
 #endif
@@ -107,22 +116,16 @@ void Logger::log_vprintf_non_main_thread_(uint8_t level, const char *tag, int li
   // RAII guard automatically resets on return
 }
 #else
-// Implementation for single-task platforms (ESP8266, RP2040, Zephyr)
-// TODO: Zephyr may have multiple threads (work queues, etc.) but uses this single-task path.
+// Implementation for single-task platforms (ESP8266, RP2040)
 // Logging calls are NOT thread-safe: global_recursion_guard_ is a plain bool and tx_buffer_ has no locking.
 // Not a problem in practice yet since Zephyr has no API support (logs are console-only).
 void HOT Logger::log_vprintf_(uint8_t level, const char *tag, int line, const char *format, va_list args) {  // NOLINT
   if (level > this->level_for(tag) || global_recursion_guard_)
     return;
-#ifdef USE_ZEPHYR
-  char tmp[MAX_POINTER_REPRESENTATION];
-  this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args,
-                                        this->get_thread_name_(tmp));
-#else  // Other single-task platforms don't have thread names, so pass nullptr
+  // Other single-task platforms don't have thread names, so pass nullptr
   this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args, nullptr);
-#endif
 }
-#endif  // USE_ESP32 / USE_HOST / USE_LIBRETINY
+#endif  // USE_ESP32 || USE_HOST || USE_LIBRETINY || USE_ZEPHYR
 
 #ifdef USE_STORE_LOG_STR_IN_FLASH
 // Implementation for ESP8266 with flash string support.
@@ -163,19 +166,12 @@ Logger::Logger(uint32_t baud_rate, size_t tx_buffer_size) : baud_rate_(baud_rate
 }
 #ifdef USE_ESPHOME_TASK_LOG_BUFFER
 void Logger::init_log_buffer(size_t total_buffer_size) {
-#ifdef USE_HOST
   // Host uses slot count instead of byte size
-  // NOLINTNEXTLINE(cppcoreguidelines-owning-memory) - allocated once, never freed
-  this->log_buffer_ = new logger::TaskLogBufferHost(total_buffer_size);
-#elif defined(USE_ESP32)
   // NOLINTNEXTLINE(cppcoreguidelines-owning-memory) - allocated once, never freed
   this->log_buffer_ = new logger::TaskLogBuffer(total_buffer_size);
-#elif defined(USE_LIBRETINY)
-  // NOLINTNEXTLINE(cppcoreguidelines-owning-memory) - allocated once, never freed
-  this->log_buffer_ = new logger::TaskLogBufferLibreTiny(total_buffer_size);
-#endif
 
-#if defined(USE_ESP32) || defined(USE_LIBRETINY)
+// Zephyr needs loop working to check when CDC port is open
+#if !(defined(USE_ZEPHYR) || defined(USE_LOGGER_USB_CDC))
   // Start with loop disabled when using task buffer (unless using USB CDC on ESP32)
   // The loop will be enabled automatically when messages arrive
   this->disable_loop_when_buffer_empty_();
@@ -183,52 +179,33 @@ void Logger::init_log_buffer(size_t total_buffer_size) {
 }
 #endif
 
-#ifdef USE_ESPHOME_TASK_LOG_BUFFER
-void Logger::loop() { this->process_messages_(); }
+#if defined(USE_ESPHOME_TASK_LOG_BUFFER) || (defined(USE_ZEPHYR) && defined(USE_LOGGER_USB_CDC))
+void Logger::loop() {
+  this->process_messages_();
+#if defined(USE_ZEPHYR) && defined(USE_LOGGER_USB_CDC)
+  this->cdc_loop_();
+#endif
+}
 #endif
 
 void Logger::process_messages_() {
 #ifdef USE_ESPHOME_TASK_LOG_BUFFER
   // Process any buffered messages when available
   if (this->log_buffer_->has_messages()) {
-#ifdef USE_HOST
-    logger::TaskLogBufferHost::LogMessage *message;
-    while (this->log_buffer_->get_message_main_loop(&message)) {
-      const char *thread_name = message->thread_name[0] != '\0' ? message->thread_name : nullptr;
-      LogBuffer buf{this->tx_buffer_, this->tx_buffer_size_};
-      this->format_buffered_message_and_notify_(message->level, message->tag, message->line, thread_name, message->text,
-                                                message->text_length, buf);
-      this->log_buffer_->release_message_main_loop();
-      this->write_log_buffer_to_console_(buf);
-    }
-#elif defined(USE_ESP32)
     logger::TaskLogBuffer::LogMessage *message;
-    const char *text;
-    void *received_token;
-    while (this->log_buffer_->borrow_message_main_loop(&message, &text, &received_token)) {
+    uint16_t text_length;
+    while (this->log_buffer_->borrow_message_main_loop(message, text_length)) {
       const char *thread_name = message->thread_name[0] != '\0' ? message->thread_name : nullptr;
       LogBuffer buf{this->tx_buffer_, this->tx_buffer_size_};
-      this->format_buffered_message_and_notify_(message->level, message->tag, message->line, thread_name, text,
-                                                message->text_length, buf);
-      // Release the message to allow other tasks to use it as soon as possible
-      this->log_buffer_->release_message_main_loop(received_token);
-      this->write_log_buffer_to_console_(buf);
-    }
-#elif defined(USE_LIBRETINY)
-    logger::TaskLogBufferLibreTiny::LogMessage *message;
-    const char *text;
-    while (this->log_buffer_->borrow_message_main_loop(&message, &text)) {
-      const char *thread_name = message->thread_name[0] != '\0' ? message->thread_name : nullptr;
-      LogBuffer buf{this->tx_buffer_, this->tx_buffer_size_};
-      this->format_buffered_message_and_notify_(message->level, message->tag, message->line, thread_name, text,
-                                                message->text_length, buf);
+      this->format_buffered_message_and_notify_(message->level, message->tag, message->line, thread_name,
+                                                message->text_data(), text_length, buf);
       // Release the message to allow other tasks to use it as soon as possible
       this->log_buffer_->release_message_main_loop();
       this->write_log_buffer_to_console_(buf);
     }
-#endif
   }
-#if defined(USE_ESP32) || defined(USE_LIBRETINY)
+// Zephyr needs loop working to check when CDC port is open
+#if !(defined(USE_ZEPHYR) || defined(USE_LOGGER_USB_CDC))
   else {
     // No messages to process, disable loop if appropriate
     // This reduces overhead when there's no async logging activity

esphome/components/logger/logger.h

@@ -13,15 +13,11 @@
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
-#ifdef USE_ESPHOME_TASK_LOG_BUFFER
-#ifdef USE_HOST
+#include "log_buffer.h"
 #include "task_log_buffer_host.h"
-#elif defined(USE_ESP32)
 #include "task_log_buffer_esp32.h"
-#elif defined(USE_LIBRETINY)
 #include "task_log_buffer_libretiny.h"
-#endif
-#endif
+#include "task_log_buffer_zephyr.h"
 
 #ifdef USE_ARDUINO
 #if defined(USE_ESP8266)
@@ -97,195 +93,10 @@ struct CStrCompare {
 };
 #endif
 
-// ANSI color code last digit (30-38 range, store only last digit to save RAM)
-static constexpr char LOG_LEVEL_COLOR_DIGIT[] = {
-    '\0',  // NONE
-    '1',   // ERROR (31 = red)
-    '3',   // WARNING (33 = yellow)
-    '2',   // INFO (32 = green)
-    '5',   // CONFIG (35 = magenta)
-    '6',   // DEBUG (36 = cyan)
-    '7',   // VERBOSE (37 = gray)
-    '8',   // VERY_VERBOSE (38 = white)
-};
-
-static constexpr char LOG_LEVEL_LETTER_CHARS[] = {
-    '\0',  // NONE
-    'E',   // ERROR
-    'W',   // WARNING
-    'I',   // INFO
-    'C',   // CONFIG
-    'D',   // DEBUG
-    'V',   // VERBOSE (VERY_VERBOSE uses two 'V's)
-};
-
-// Maximum header size: 35 bytes fixed + 32 bytes tag + 16 bytes thread name = 83 bytes (45 byte safety margin)
-static constexpr uint16_t MAX_HEADER_SIZE = 128;
-
-// "0x" + 2 hex digits per byte + '\0'
-static constexpr size_t MAX_POINTER_REPRESENTATION = 2 + sizeof(void *) * 2 + 1;
-
 // Stack buffer size for retrieving thread/task names from the OS
 // macOS allows up to 64 bytes, Linux up to 16
 static constexpr size_t THREAD_NAME_BUF_SIZE = 64;
 
-// Buffer wrapper for log formatting functions
-struct LogBuffer {
-  char *data;
-  uint16_t size;
-  uint16_t pos{0};
-  // Replaces the null terminator with a newline for console output.
-  // Must be called after notify_listeners_() since listeners need null-terminated strings.
-  // Console output uses length-based writes (buf.pos), so null terminator is not needed.
-  void terminate_with_newline() {
-    if (this->pos < this->size) {
-      this->data[this->pos++] = '\n';
-    } else if (this->size > 0) {
-      // Buffer was full - replace last char with newline to ensure it's visible
-      this->data[this->size - 1] = '\n';
-      this->pos = this->size;
-    }
-  }
-  void HOT write_header(uint8_t level, const char *tag, int line, const char *thread_name) {
-    // Early return if insufficient space - intentionally don't update pos to prevent partial writes
-    if (this->pos + MAX_HEADER_SIZE > this->size)
-      return;
-
-    char *p = this->current_();
-
-    // Write ANSI color
-    this->write_ansi_color_(p, level);
-
-    // Construct: [LEVEL][tag:line]
-    *p++ = '[';
-    if (level != 0) {
-      if (level >= 7) {
-        *p++ = 'V';  // VERY_VERBOSE = "VV"
-        *p++ = 'V';
-      } else {
-        *p++ = LOG_LEVEL_LETTER_CHARS[level];
-      }
-    }
-    *p++ = ']';
-    *p++ = '[';
-
-    // Copy tag
-    this->copy_string_(p, tag);
-
-    *p++ = ':';
-
-    // Format line number without modulo operations
-    if (line > 999) [[unlikely]] {
-      int thousands = line / 1000;
-      *p++ = '0' + thousands;
-      line -= thousands * 1000;
-    }
-    int hundreds = line / 100;
-    int remainder = line - hundreds * 100;
-    int tens = remainder / 10;
-    *p++ = '0' + hundreds;
-    *p++ = '0' + tens;
-    *p++ = '0' + (remainder - tens * 10);
-    *p++ = ']';
-
-#if defined(USE_ESP32) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR) || defined(USE_HOST)
-    // Write thread name with bold red color
-    if (thread_name != nullptr) {
-      this->write_ansi_color_(p, 1);  // Bold red for thread name
-      *p++ = '[';
-      this->copy_string_(p, thread_name);
-      *p++ = ']';
-      this->write_ansi_color_(p, level);  // Restore original color
-    }
-#endif
-
-    *p++ = ':';
-    *p++ = ' ';
-
-    this->pos = p - this->data;
-  }
-  void HOT format_body(const char *format, va_list args) {
-    this->format_vsnprintf_(format, args);
-    this->finalize_();
-  }
-#ifdef USE_STORE_LOG_STR_IN_FLASH
-  void HOT format_body_P(PGM_P format, va_list args) {
-    this->format_vsnprintf_P_(format, args);
-    this->finalize_();
-  }
-#endif
-  void write_body(const char *text, uint16_t text_length) {
-    this->write_(text, text_length);
-    this->finalize_();
-  }
-
- private:
-  bool full_() const { return this->pos >= this->size; }
-  uint16_t remaining_() const { return this->size - this->pos; }
-  char *current_() { return this->data + this->pos; }
-  void write_(const char *value, uint16_t length) {
-    const uint16_t available = this->remaining_();
-    const uint16_t copy_len = (length < available) ? length : available;
-    if (copy_len > 0) {
-      memcpy(this->current_(), value, copy_len);
-      this->pos += copy_len;
-    }
-  }
-  void finalize_() {
-    // Write color reset sequence
-    static constexpr uint16_t RESET_COLOR_LEN = sizeof(ESPHOME_LOG_RESET_COLOR) - 1;
-    this->write_(ESPHOME_LOG_RESET_COLOR, RESET_COLOR_LEN);
-    // Null terminate
-    this->data[this->full_() ? this->size - 1 : this->pos] = '\0';
-  }
-  void strip_trailing_newlines_() {
-    while (this->pos > 0 && this->data[this->pos - 1] == '\n')
-      this->pos--;
-  }
-  void process_vsnprintf_result_(int ret) {
-    if (ret < 0)
-      return;
-    const uint16_t rem = this->remaining_();
-    this->pos += (ret >= rem) ? (rem - 1) : static_cast<uint16_t>(ret);
-    this->strip_trailing_newlines_();
-  }
-  void format_vsnprintf_(const char *format, va_list args) {
-    if (this->full_())
-      return;
-    this->process_vsnprintf_result_(vsnprintf(this->current_(), this->remaining_(), format, args));
-  }
-#ifdef USE_STORE_LOG_STR_IN_FLASH
-  void format_vsnprintf_P_(PGM_P format, va_list args) {
-    if (this->full_())
-      return;
-    this->process_vsnprintf_result_(vsnprintf_P(this->current_(), this->remaining_(), format, args));
-  }
-#endif
-  // Write ANSI color escape sequence to buffer, updates pointer in place
-  // Caller is responsible for ensuring buffer has sufficient space
-  void write_ansi_color_(char *&p, uint8_t level) {
-    if (level == 0)
-      return;
-    // Direct buffer fill: "\033[{bold};3{color}m" (7 bytes)
-    *p++ = '\033';
-    *p++ = '[';
-    *p++ = (level == 1) ? '1' : '0';  // Only ERROR is bold
-    *p++ = ';';
-    *p++ = '3';
-    *p++ = LOG_LEVEL_COLOR_DIGIT[level];
-    *p++ = 'm';
-  }
-  // Copy string without null terminator, updates pointer in place
-  // Caller is responsible for ensuring buffer has sufficient space
-  void copy_string_(char *&p, const char *str) {
-    const size_t len = strlen(str);
-    // NOLINTNEXTLINE(bugprone-not-null-terminated-result) - intentionally no null terminator, building string piece by
-    // piece
-    memcpy(p, str, len);
-    p += len;
-  }
-};
-
 #if defined(USE_ESP32) || defined(USE_ESP8266) || defined(USE_RP2040) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR)
 /** Enum for logging UART selection
  *
@@ -411,11 +222,14 @@ class Logger : public Component {
     bool &flag_;
   };
 
-#if defined(USE_ESP32) || defined(USE_HOST) || defined(USE_LIBRETINY)
+#if defined(USE_ESP32) || defined(USE_HOST) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR)
   // Handles non-main thread logging only (~0.1% of calls)
   // thread_name is resolved by the caller from the task handle, avoiding redundant lookups
   void log_vprintf_non_main_thread_(uint8_t level, const char *tag, int line, const char *format, va_list args,
                                     const char *thread_name);
+#endif
+#if defined(USE_ZEPHYR) && defined(USE_LOGGER_USB_CDC)
+  void cdc_loop_();
 #endif
   void process_messages_();
   void write_msg_(const char *msg, uint16_t len);
@@ -534,13 +348,7 @@ class Logger : public Component {
   std::vector<LoggerLevelListener *> level_listeners_;  // Log level change listeners
 #endif
 #ifdef USE_ESPHOME_TASK_LOG_BUFFER
-#ifdef USE_HOST
-  logger::TaskLogBufferHost *log_buffer_{nullptr};  // Allocated once, never freed
-#elif defined(USE_ESP32)
   logger::TaskLogBuffer *log_buffer_{nullptr};  // Allocated once, never freed
-#elif defined(USE_LIBRETINY)
-  logger::TaskLogBufferLibreTiny *log_buffer_{nullptr};  // Allocated once, never freed
-#endif
 #endif
 
   // Group smaller types together at the end
@@ -552,7 +360,7 @@ class Logger : public Component {
 #ifdef USE_LIBRETINY
   UARTSelection uart_{UART_SELECTION_DEFAULT};
 #endif
-#if defined(USE_ESP32) || defined(USE_HOST) || defined(USE_LIBRETINY)
+#if defined(USE_ESP32) || defined(USE_HOST) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR)
   bool main_task_recursion_guard_{false};
 #ifdef USE_LIBRETINY
   bool non_main_task_recursion_guard_{false};  // Shared guard for all non-main tasks on LibreTiny
@@ -595,8 +403,10 @@ class Logger : public Component {
   }
 
 #elif defined(USE_ZEPHYR)
-  const char *HOT get_thread_name_(std::span<char> buff) {
-    k_tid_t current_task = k_current_get();
+  const char *HOT get_thread_name_(std::span<char> buff, k_tid_t current_task = nullptr) {
+    if (current_task == nullptr) {
+      current_task = k_current_get();
+    }
     if (current_task == main_task_) {
       return nullptr;  // Main task
     }
@@ -635,7 +445,7 @@ class Logger : public Component {
   // Create RAII guard for non-main task recursion
   inline NonMainTaskRecursionGuard make_non_main_task_guard_() { return NonMainTaskRecursionGuard(log_recursion_key_); }
 
-#elif defined(USE_LIBRETINY)
+#elif defined(USE_LIBRETINY) || defined(USE_ZEPHYR)
   // LibreTiny doesn't have FreeRTOS TLS, so use a simple approach:
   // - Main task uses dedicated boolean (same as ESP32)
   // - Non-main tasks share a single recursion guard
@@ -643,6 +453,8 @@ class Logger : public Component {
   // - Recursion from logging within logging is the main concern
   // - Cross-task "recursion" is prevented by the buffer mutex anyway
   // - Missing a recursive call from another task is acceptable (falls back to direct output)
+  //
+  // Zephyr use __thread as TLS
 
   // Check if non-main task is already in recursion
   inline bool HOT is_non_main_task_recursive_() const { return non_main_task_recursion_guard_; }
@@ -651,7 +463,8 @@ class Logger : public Component {
   inline RecursionGuard make_non_main_task_guard_() { return RecursionGuard(non_main_task_recursion_guard_); }
 #endif
 
-#if defined(USE_ESP32) || defined(USE_LIBRETINY)
+// Zephyr needs loop working to check when CDC port is open
+#if defined(USE_ESPHOME_TASK_LOG_BUFFER) && !(defined(USE_ZEPHYR) || defined(USE_LOGGER_USB_CDC))
   // Disable loop when task buffer is empty (with USB CDC check on ESP32)
   inline void disable_loop_when_buffer_empty_() {
     // Thread safety note: This is safe even if another task calls enable_loop_soon_any_context()

esphome/components/logger/logger_zephyr.cpp

@@ -14,7 +14,7 @@ namespace esphome::logger {
 static const char *const TAG = "logger";
 
 #ifdef USE_LOGGER_USB_CDC
-void Logger::loop() {
+void Logger::cdc_loop_() {
   if (this->uart_ != UART_SELECTION_USB_CDC || this->uart_dev_ == nullptr) {
     return;
   }

esphome/components/logger/task_log_buffer_esp32.cpp

@@ -31,8 +31,8 @@ TaskLogBuffer::~TaskLogBuffer() {
   }
 }
 
-bool TaskLogBuffer::borrow_message_main_loop(LogMessage **message, const char **text, void **received_token) {
-  if (message == nullptr || text == nullptr || received_token == nullptr) {
+bool TaskLogBuffer::borrow_message_main_loop(LogMessage *&message, uint16_t &text_length) {
+  if (this->current_token_) {
     return false;
   }
 
@@ -43,18 +43,19 @@ bool TaskLogBuffer::borrow_message_main_loop(LogMessage **message, const char **
   }
 
   LogMessage *msg = static_cast<LogMessage *>(received_item);
-  *message = msg;
-  *text = msg->text_data();
-  *received_token = received_item;
+  message = msg;
+  text_length = msg->text_length;
+  this->current_token_ = received_item;
 
   return true;
 }
 
-void TaskLogBuffer::release_message_main_loop(void *token) {
-  if (token == nullptr) {
+void TaskLogBuffer::release_message_main_loop() {
+  if (this->current_token_ == nullptr) {
     return;
   }
-  vRingbufferReturnItem(ring_buffer_, token);
+  vRingbufferReturnItem(ring_buffer_, this->current_token_);
+  this->current_token_ = nullptr;
   // Update counter to mark all messages as processed
   last_processed_counter_ = message_counter_.load(std::memory_order_relaxed);
 }

esphome/components/logger/task_log_buffer_esp32.h

@@ -52,10 +52,10 @@ class TaskLogBuffer {
   ~TaskLogBuffer();
 
   // NOT thread-safe - borrow a message from the ring buffer, only call from main loop
-  bool borrow_message_main_loop(LogMessage **message, const char **text, void **received_token);
+  bool borrow_message_main_loop(LogMessage *&message, uint16_t &text_length);
 
   // NOT thread-safe - release a message buffer and update the counter, only call from main loop
-  void release_message_main_loop(void *token);
+  void release_message_main_loop();
 
   // Thread-safe - send a message to the ring buffer from any thread
   bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
@@ -78,6 +78,7 @@ class TaskLogBuffer {
   // Atomic counter for message tracking (only differences matter)
   std::atomic<uint16_t> message_counter_{0};    // Incremented when messages are committed
   mutable uint16_t last_processed_counter_{0};  // Tracks last processed message
+  void *current_token_{nullptr};
 };
 
 }  // namespace esphome::logger

esphome/components/logger/task_log_buffer_host.cpp

@@ -10,16 +10,16 @@
 
 namespace esphome::logger {
 
-TaskLogBufferHost::TaskLogBufferHost(size_t slot_count) : slot_count_(slot_count) {
+TaskLogBuffer::TaskLogBuffer(size_t slot_count) : slot_count_(slot_count) {
   // Allocate message slots
   this->slots_ = std::make_unique<LogMessage[]>(slot_count);
 }
 
-TaskLogBufferHost::~TaskLogBufferHost() {
+TaskLogBuffer::~TaskLogBuffer() {
   // unique_ptr handles cleanup automatically
 }
 
-int TaskLogBufferHost::acquire_write_slot_() {
+int TaskLogBuffer::acquire_write_slot_() {
   // Try to reserve a slot using compare-and-swap
   size_t current_reserve = this->reserve_index_.load(std::memory_order_relaxed);
 
@@ -43,7 +43,7 @@ int TaskLogBufferHost::acquire_write_slot_() {
   }
 }
 
-void TaskLogBufferHost::commit_write_slot_(int slot_index) {
+void TaskLogBuffer::commit_write_slot_(int slot_index) {
   // Mark the slot as ready for reading
   this->slots_[slot_index].ready.store(true, std::memory_order_release);
 
@@ -70,8 +70,8 @@ void TaskLogBufferHost::commit_write_slot_(int slot_index) {
   }
 }
 
-bool TaskLogBufferHost::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
-                                                 const char *format, va_list args) {
+bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
+                                             const char *format, va_list args) {
   // Acquire a slot
   int slot_index = this->acquire_write_slot_();
   if (slot_index < 0) {
@@ -115,11 +115,7 @@ bool TaskLogBufferHost::send_message_thread_safe(uint8_t level, const char *tag,
   return true;
 }
 
-bool TaskLogBufferHost::get_message_main_loop(LogMessage **message) {
-  if (message == nullptr) {
-    return false;
-  }
-
+bool TaskLogBuffer::borrow_message_main_loop(LogMessage *&message, uint16_t &text_length) {
   size_t current_read = this->read_index_.load(std::memory_order_relaxed);
   size_t current_write = this->write_index_.load(std::memory_order_acquire);
 
@@ -134,11 +130,12 @@ bool TaskLogBufferHost::get_message_main_loop(LogMessage **message) {
     return false;
   }
 
-  *message = &msg;
+  message = &msg;
+  text_length = msg.text_length;
   return true;
 }
 
-void TaskLogBufferHost::release_message_main_loop() {
+void TaskLogBuffer::release_message_main_loop() {
   size_t current_read = this->read_index_.load(std::memory_order_relaxed);
 
   // Clear the ready flag

esphome/components/logger/task_log_buffer_host.h

@@ -21,12 +21,12 @@ namespace esphome::logger {
  *
  * Threading Model: Multi-Producer Single-Consumer (MPSC)
  * - Multiple threads can safely call send_message_thread_safe() concurrently
- * - Only the main loop thread calls get_message_main_loop() and release_message_main_loop()
+ * - Only the main loop thread calls borrow_message_main_loop() and release_message_main_loop()
  *
  *   Producers (multiple threads)              Consumer (main loop only)
  *            │                                        │
  *            ▼                                        ▼
- *     acquire_write_slot_()                  get_message_main_loop()
+ *     acquire_write_slot_()                  bool borrow_message_main_loop()
  *       CAS on reserve_index_                  read write_index_
  *            │                                   check ready flag
  *            ▼                                        │
@@ -48,7 +48,7 @@ namespace esphome::logger {
  * - Atomic CAS for slot reservation allows multiple producers without locks
  * - Single consumer (main loop) processes messages in order
  */
-class TaskLogBufferHost {
+class TaskLogBuffer {
  public:
   // Default number of message slots - host has plenty of memory
   static constexpr size_t DEFAULT_SLOT_COUNT = 64;
@@ -71,15 +71,16 @@ class TaskLogBufferHost {
       thread_name[0] = '\0';
       text[0] = '\0';
     }
+    inline char *text_data() { return this->text; }
   };
 
   /// Constructor that takes the number of message slots
-  explicit TaskLogBufferHost(size_t slot_count);
-  ~TaskLogBufferHost();
+  explicit TaskLogBuffer(size_t slot_count);
+  ~TaskLogBuffer();
 
   // NOT thread-safe - get next message from buffer, only call from main loop
   // Returns true if a message was retrieved, false if buffer is empty
-  bool get_message_main_loop(LogMessage **message);
+  bool borrow_message_main_loop(LogMessage *&message, uint16_t &text_length);
 
   // NOT thread-safe - release the message after processing, only call from main loop
   void release_message_main_loop();

esphome/components/logger/task_log_buffer_libretiny.cpp

@@ -8,7 +8,7 @@
 
 namespace esphome::logger {
 
-TaskLogBufferLibreTiny::TaskLogBufferLibreTiny(size_t total_buffer_size) {
+TaskLogBuffer::TaskLogBuffer(size_t total_buffer_size) {
   this->size_ = total_buffer_size;
   // Allocate memory for the circular buffer using ESPHome's RAM allocator
   RAMAllocator<uint8_t> allocator;
@@ -17,7 +17,7 @@ TaskLogBufferLibreTiny::TaskLogBufferLibreTiny(size_t total_buffer_size) {
   this->mutex_ = xSemaphoreCreateMutex();
 }
 
-TaskLogBufferLibreTiny::~TaskLogBufferLibreTiny() {
+TaskLogBuffer::~TaskLogBuffer() {
   if (this->mutex_ != nullptr) {
     vSemaphoreDelete(this->mutex_);
     this->mutex_ = nullptr;
@@ -29,7 +29,7 @@ TaskLogBufferLibreTiny::~TaskLogBufferLibreTiny() {
   }
 }
 
-size_t TaskLogBufferLibreTiny::available_contiguous_space() const {
+size_t TaskLogBuffer::available_contiguous_space() const {
   if (this->head_ >= this->tail_) {
     // head is ahead of or equal to tail
     // Available space is from head to end, plus from start to tail
@@ -47,11 +47,7 @@ size_t TaskLogBufferLibreTiny::available_contiguous_space() const {
   }
 }
 
-bool TaskLogBufferLibreTiny::borrow_message_main_loop(LogMessage **message, const char **text) {
-  if (message == nullptr || text == nullptr) {
-    return false;
-  }
-
+bool TaskLogBuffer::borrow_message_main_loop(LogMessage *&message, uint16_t &text_length) {
   // Check if buffer was initialized successfully
   if (this->mutex_ == nullptr || this->storage_ == nullptr) {
     return false;
@@ -77,15 +73,15 @@ bool TaskLogBufferLibreTiny::borrow_message_main_loop(LogMessage **message, cons
     this->tail_ = 0;
     msg = reinterpret_cast<LogMessage *>(this->storage_);
   }
-  *message = msg;
-  *text = msg->text_data();
+  message = msg;
+  text_length = msg->text_length;
   this->current_message_size_ = message_total_size(msg->text_length);
 
   // Keep mutex held until release_message_main_loop()
   return true;
 }
 
-void TaskLogBufferLibreTiny::release_message_main_loop() {
+void TaskLogBuffer::release_message_main_loop() {
   // Advance tail past the current message
   this->tail_ += this->current_message_size_;
 
@@ -100,8 +96,8 @@ void TaskLogBufferLibreTiny::release_message_main_loop() {
   xSemaphoreGive(this->mutex_);
 }
 
-bool TaskLogBufferLibreTiny::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line,
-                                                      const char *thread_name, const char *format, va_list args) {
+bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
+                                             const char *format, va_list args) {
   // First, calculate the exact length needed using a null buffer (no actual writing)
   va_list args_copy;
   va_copy(args_copy, args);

esphome/components/logger/task_log_buffer_libretiny.h

@@ -40,7 +40,7 @@ namespace esphome::logger {
  * - Volatile counter enables fast has_messages() without lock overhead
  * - If message doesn't fit at end, padding is added and message wraps to start
  */
-class TaskLogBufferLibreTiny {
+class TaskLogBuffer {
  public:
   // Structure for a log message header (text data follows immediately after)
   struct LogMessage {
@@ -60,11 +60,11 @@ class TaskLogBufferLibreTiny {
   static constexpr uint8_t PADDING_MARKER_LEVEL = 0xFF;
 
   // Constructor that takes a total buffer size
-  explicit TaskLogBufferLibreTiny(size_t total_buffer_size);
-  ~TaskLogBufferLibreTiny();
+  explicit TaskLogBuffer(size_t total_buffer_size);
+  ~TaskLogBuffer();
 
   // NOT thread-safe - borrow a message from the buffer, only call from main loop
-  bool borrow_message_main_loop(LogMessage **message, const char **text);
+  bool borrow_message_main_loop(LogMessage *&message, uint16_t &text_length);
 
   // NOT thread-safe - release a message buffer, only call from main loop
   void release_message_main_loop();

esphome/components/logger/task_log_buffer_zephyr.cpp

@@ -0,0 +1,116 @@
+#ifdef USE_ZEPHYR
+
+#include "task_log_buffer_zephyr.h"
+
+namespace esphome::logger {
+
+__thread bool non_main_task_recursion_guard_;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+
+#ifdef USE_ESPHOME_TASK_LOG_BUFFER
+
+static inline uint32_t total_size_in_32bit_words(uint16_t text_length) {
+  // Calculate total size in 32-bit words needed (header + text length + null terminator + 3(4 bytes alignment)
+  return (sizeof(TaskLogBuffer::LogMessage) + text_length + 1 + 3) / sizeof(uint32_t);
+}
+
+static inline uint32_t get_wlen(const mpsc_pbuf_generic *item) {
+  return total_size_in_32bit_words(reinterpret_cast<const TaskLogBuffer::LogMessage *>(item)->text_length);
+}
+
+TaskLogBuffer::TaskLogBuffer(size_t total_buffer_size) {
+  // alignment to 4 bytes
+  total_buffer_size = (total_buffer_size + 3) / sizeof(uint32_t);
+  this->mpsc_config_.buf = new uint32_t[total_buffer_size];
+  this->mpsc_config_.size = total_buffer_size;
+  this->mpsc_config_.flags = MPSC_PBUF_MODE_OVERWRITE;
+  this->mpsc_config_.get_wlen = get_wlen,
+
+  mpsc_pbuf_init(&this->log_buffer_, &this->mpsc_config_);
+}
+
+TaskLogBuffer::~TaskLogBuffer() { delete[] this->mpsc_config_.buf; }
+
+bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
+                                             const char *format, va_list args) {
+  // First, calculate the exact length needed using a null buffer (no actual writing)
+  va_list args_copy;
+  va_copy(args_copy, args);
+  int ret = vsnprintf(nullptr, 0, format, args_copy);
+  va_end(args_copy);
+
+  if (ret <= 0) {
+    return false;  // Formatting error or empty message
+  }
+
+  // Calculate actual text length (capped to maximum size)
+  static constexpr size_t MAX_TEXT_SIZE = 255;
+  size_t text_length = (static_cast<size_t>(ret) > MAX_TEXT_SIZE) ? MAX_TEXT_SIZE : ret;
+  size_t total_size = total_size_in_32bit_words(text_length);
+  auto *msg = reinterpret_cast<LogMessage *>(mpsc_pbuf_alloc(&this->log_buffer_, total_size, K_NO_WAIT));
+  if (msg == nullptr) {
+    return false;
+  }
+  msg->level = level;
+  msg->tag = tag;
+  msg->line = line;
+  strncpy(msg->thread_name, thread_name, sizeof(msg->thread_name) - 1);
+  msg->thread_name[sizeof(msg->thread_name) - 1] = '\0';  // Ensure null termination
+
+  // Format the message text directly into the acquired memory
+  // We add 1 to text_length to ensure space for null terminator during formatting
+  char *text_area = msg->text_data();
+  ret = vsnprintf(text_area, text_length + 1, format, args);
+
+  // Handle unexpected formatting error (ret < 0 is encoding error; ret == 0 is valid empty output)
+  if (ret < 0) {
+    // this should not happen, vsnprintf was called already once
+    // fill with '\n' to not call mpsc_pbuf_free from producer
+    // it will be trimmed anyway
+    for (size_t i = 0; i < text_length; ++i) {
+      text_area[i] = '\n';
+    }
+    text_area[text_length] = 0;
+    // do not return false to free the buffer from main thread
+  }
+
+  msg->text_length = text_length;
+
+  mpsc_pbuf_commit(&this->log_buffer_, reinterpret_cast<mpsc_pbuf_generic *>(msg));
+  return true;
+}
+
+bool TaskLogBuffer::borrow_message_main_loop(LogMessage *&message, uint16_t &text_length) {
+  if (this->current_token_) {
+    return false;
+  }
+
+  this->current_token_ = mpsc_pbuf_claim(&this->log_buffer_);
+
+  if (this->current_token_ == nullptr) {
+    return false;
+  }
+
+  // we claimed buffer already, const_cast is safe here
+  message = const_cast<LogMessage *>(reinterpret_cast<const LogMessage *>(this->current_token_));
+
+  text_length = message->text_length;
+  // Remove trailing newlines
+  while (text_length > 0 && message->text_data()[text_length - 1] == '\n') {
+    text_length--;
+  }
+
+  return true;
+}
+
+void TaskLogBuffer::release_message_main_loop() {
+  if (this->current_token_ == nullptr) {
+    return;
+  }
+  mpsc_pbuf_free(&this->log_buffer_, this->current_token_);
+  this->current_token_ = nullptr;
+}
+#endif  // USE_ESPHOME_TASK_LOG_BUFFER
+
+}  // namespace esphome::logger
+
+#endif  // USE_ZEPHYR

esphome/components/logger/task_log_buffer_zephyr.h

@@ -0,0 +1,66 @@
+#pragma once
+
+#ifdef USE_ZEPHYR
+
+#include "esphome/core/defines.h"
+#include "esphome/core/helpers.h"
+#include <zephyr/sys/mpsc_pbuf.h>
+
+namespace esphome::logger {
+
+// "0x" + 2 hex digits per byte + '\0'
+static constexpr size_t MAX_POINTER_REPRESENTATION = 2 + sizeof(void *) * 2 + 1;
+
+extern __thread bool non_main_task_recursion_guard_;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+
+#ifdef USE_ESPHOME_TASK_LOG_BUFFER
+
+class TaskLogBuffer {
+ public:
+  // Structure for a log message header (text data follows immediately after)
+  struct LogMessage {
+    MPSC_PBUF_HDR;  // this is only 2 bits but no more than 30 bits directly after
+    uint16_t line;  // Source code line number
+    uint8_t level;  // Log level (0-7)
+#if defined(CONFIG_THREAD_NAME)
+    char thread_name[CONFIG_THREAD_MAX_NAME_LEN];  // Store thread name directly (only used for non-main threads)
+#else
+    char thread_name[MAX_POINTER_REPRESENTATION];  // Store thread name directly (only used for non-main threads)
+#endif
+    const char *tag;       // We store the pointer, assuming tags are static
+    uint16_t text_length;  // Length of the message text (up to ~64KB)
+
+    // Methods for accessing message contents
+    inline char *text_data() { return reinterpret_cast<char *>(this) + sizeof(LogMessage); }
+  };
+  // Constructor that takes a total buffer size
+  explicit TaskLogBuffer(size_t total_buffer_size);
+  ~TaskLogBuffer();
+
+  // Check if there are messages ready to be processed using an atomic counter for performance
+  inline bool HOT has_messages() { return mpsc_pbuf_is_pending(&this->log_buffer_); }
+
+  // Get the total buffer size in bytes
+  inline size_t size() const { return this->mpsc_config_.size * sizeof(uint32_t); }
+
+  // NOT thread-safe - borrow a message from the ring buffer, only call from main loop
+  bool borrow_message_main_loop(LogMessage *&message, uint16_t &text_length);
+
+  // NOT thread-safe - release a message buffer and update the counter, only call from main loop
+  void release_message_main_loop();
+
+  // Thread-safe - send a message to the ring buffer from any thread
+  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
+                                const char *format, va_list args);
+
+ protected:
+  mpsc_pbuf_buffer_config mpsc_config_{};
+  mpsc_pbuf_buffer log_buffer_{};
+  const mpsc_pbuf_generic *current_token_{};
+};
+
+#endif  // USE_ESPHOME_TASK_LOG_BUFFER
+
+}  // namespace esphome::logger
+
+#endif  // USE_ZEPHYR

esphome/components/mqtt/mqtt_cover.cpp

@@ -67,17 +67,26 @@ void MQTTCoverComponent::dump_config() {
   auto traits = this->cover_->get_traits();
   bool has_command_topic = traits.get_supports_position() || !traits.get_supports_tilt();
   LOG_MQTT_COMPONENT(true, has_command_topic);
+  char topic_buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
+#ifdef USE_MQTT_COVER_JSON
+  if (this->use_json_format_) {
+    ESP_LOGCONFIG(TAG, "  JSON State Payload: YES");
+  } else {
+#endif
+    if (traits.get_supports_position()) {
+      ESP_LOGCONFIG(TAG, "  Position State Topic: '%s'", this->get_position_state_topic_to(topic_buf).c_str());
+    }
+    if (traits.get_supports_tilt()) {
+      ESP_LOGCONFIG(TAG, "  Tilt State Topic: '%s'", this->get_tilt_state_topic_to(topic_buf).c_str());
+    }
+#ifdef USE_MQTT_COVER_JSON
+  }
+#endif
   if (traits.get_supports_position()) {
-    ESP_LOGCONFIG(TAG,
-                  "  Position State Topic: '%s'\n"
-                  "  Position Command Topic: '%s'",
-                  this->get_position_state_topic().c_str(), this->get_position_command_topic().c_str());
+    ESP_LOGCONFIG(TAG, "  Position Command Topic: '%s'", this->get_position_command_topic_to(topic_buf).c_str());
   }
   if (traits.get_supports_tilt()) {
-    ESP_LOGCONFIG(TAG,
-                  "  Tilt State Topic: '%s'\n"
-                  "  Tilt Command Topic: '%s'",
-                  this->get_tilt_state_topic().c_str(), this->get_tilt_command_topic().c_str());
+    ESP_LOGCONFIG(TAG, "  Tilt Command Topic: '%s'", this->get_tilt_command_topic_to(topic_buf).c_str());
   }
 }
 void MQTTCoverComponent::send_discovery(JsonObject root, mqtt::SendDiscoveryConfig &config) {
@@ -92,13 +101,33 @@ void MQTTCoverComponent::send_discovery(JsonObject root, mqtt::SendDiscoveryConf
   if (traits.get_is_assumed_state()) {
     root[MQTT_OPTIMISTIC] = true;
   }
-  if (traits.get_supports_position()) {
-    root[MQTT_POSITION_TOPIC] = this->get_position_state_topic();
-    root[MQTT_SET_POSITION_TOPIC] = this->get_position_command_topic();
-  }
-  if (traits.get_supports_tilt()) {
-    root[MQTT_TILT_STATUS_TOPIC] = this->get_tilt_state_topic();
-    root[MQTT_TILT_COMMAND_TOPIC] = this->get_tilt_command_topic();
+  char topic_buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
+#ifdef USE_MQTT_COVER_JSON
+  if (this->use_json_format_) {
+    // JSON mode: all state published to state_topic as JSON, use templates to extract
+    root[MQTT_VALUE_TEMPLATE] = ESPHOME_F("{{ value_json.state }}");
+    if (traits.get_supports_position()) {
+      root[MQTT_POSITION_TOPIC] = this->get_state_topic_to_(topic_buf);
+      root[MQTT_POSITION_TEMPLATE] = ESPHOME_F("{{ value_json.position }}");
+      root[MQTT_SET_POSITION_TOPIC] = this->get_position_command_topic_to(topic_buf);
+    }
+    if (traits.get_supports_tilt()) {
+      root[MQTT_TILT_STATUS_TOPIC] = this->get_state_topic_to_(topic_buf);
+      root[MQTT_TILT_STATUS_TEMPLATE] = ESPHOME_F("{{ value_json.tilt }}");
+      root[MQTT_TILT_COMMAND_TOPIC] = this->get_tilt_command_topic_to(topic_buf);
+    }
+  } else
+#endif
+  {
+    // Standard mode: separate topics for position and tilt
+    if (traits.get_supports_position()) {
+      root[MQTT_POSITION_TOPIC] = this->get_position_state_topic_to(topic_buf);
+      root[MQTT_SET_POSITION_TOPIC] = this->get_position_command_topic_to(topic_buf);
+    }
+    if (traits.get_supports_tilt()) {
+      root[MQTT_TILT_STATUS_TOPIC] = this->get_tilt_state_topic_to(topic_buf);
+      root[MQTT_TILT_COMMAND_TOPIC] = this->get_tilt_command_topic_to(topic_buf);
+    }
   }
   if (traits.get_supports_tilt() && !traits.get_supports_position()) {
     config.command_topic = false;
@@ -111,8 +140,24 @@ const EntityBase *MQTTCoverComponent::get_entity() const { return this->cover_;
 bool MQTTCoverComponent::send_initial_state() { return this->publish_state(); }
 bool MQTTCoverComponent::publish_state() {
   auto traits = this->cover_->get_traits();
-  bool success = true;
   char topic_buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
+#ifdef USE_MQTT_COVER_JSON
+  if (this->use_json_format_) {
+    return this->publish_json(this->get_state_topic_to_(topic_buf), [this, traits](JsonObject root) {
+      // NOLINTBEGIN(clang-analyzer-cplusplus.NewDeleteLeaks) false positive with ArduinoJson
+      root[ESPHOME_F("state")] = cover_state_to_mqtt_str(this->cover_->current_operation, this->cover_->position,
+                                                         traits.get_supports_position());
+      if (traits.get_supports_position()) {
+        root[ESPHOME_F("position")] = static_cast<int>(roundf(this->cover_->position * 100));
+      }
+      if (traits.get_supports_tilt()) {
+        root[ESPHOME_F("tilt")] = static_cast<int>(roundf(this->cover_->tilt * 100));
+      }
+      // NOLINTEND(clang-analyzer-cplusplus.NewDeleteLeaks)
+    });
+  }
+#endif
+  bool success = true;
   if (traits.get_supports_position()) {
     char pos[VALUE_ACCURACY_MAX_LEN];
     size_t len = value_accuracy_to_buf(pos, roundf(this->cover_->position * 100), 0);

esphome/components/mqtt/mqtt_cover.h

@@ -27,12 +27,18 @@ class MQTTCoverComponent : public mqtt::MQTTComponent {
   bool publish_state();
 
   void dump_config() override;
+#ifdef USE_MQTT_COVER_JSON
+  void set_use_json_format(bool use_json_format) { this->use_json_format_ = use_json_format; }
+#endif
 
  protected:
   const char *component_type() const override;
   const EntityBase *get_entity() const override;
 
   cover::Cover *cover_;
+#ifdef USE_MQTT_COVER_JSON
+  bool use_json_format_{false};
+#endif
 };
 
 }  // namespace esphome::mqtt

esphome/components/openthread/openthread_esp.cpp

@@ -104,7 +104,7 @@ void OpenThreadComponent::ot_main() {
   esp_cli_custom_command_init();
 #endif  // CONFIG_OPENTHREAD_CLI_ESP_EXTENSION
 
-  otLinkModeConfig link_mode_config = {0};
+  otLinkModeConfig link_mode_config{};
 #if CONFIG_OPENTHREAD_FTD
   link_mode_config.mRxOnWhenIdle = true;
   link_mode_config.mDeviceType = true;

esphome/components/rp2040/preferences.cpp

@@ -25,8 +25,8 @@ static uint8_t
     s_flash_storage[RP2040_FLASH_STORAGE_SIZE];  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 static bool s_flash_dirty = false;               // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 
-// Stack buffer size for preferences - covers virtually all real-world preferences without heap allocation
-static constexpr size_t PREF_BUFFER_SIZE = 64;
+// No preference can exceed the total flash storage, so stack buffer covers all cases.
+static constexpr size_t PREF_MAX_BUFFER_SIZE = RP2040_FLASH_STORAGE_SIZE;
 
 extern "C" uint8_t _EEPROM_start;
 
@@ -46,14 +46,14 @@ class RP2040PreferenceBackend : public ESPPreferenceBackend {
 
   bool save(const uint8_t *data, size_t len) override {
     const size_t buffer_size = len + 1;
-    SmallBufferWithHeapFallback<PREF_BUFFER_SIZE> buffer_alloc(buffer_size);
-    uint8_t *buffer = buffer_alloc.get();
-
+    if (buffer_size > PREF_MAX_BUFFER_SIZE)
+      return false;
+    uint8_t buffer[PREF_MAX_BUFFER_SIZE];
     memcpy(buffer, data, len);
-    buffer[len] = calculate_crc(buffer, buffer + len, type);
+    buffer[len] = calculate_crc(buffer, buffer + len, this->type);
 
     for (size_t i = 0; i < buffer_size; i++) {
-      uint32_t j = offset + i;
+      uint32_t j = this->offset + i;
       if (j >= RP2040_FLASH_STORAGE_SIZE)
         return false;
       uint8_t v = buffer[i];
@@ -66,17 +66,18 @@ class RP2040PreferenceBackend : public ESPPreferenceBackend {
   }
   bool load(uint8_t *data, size_t len) override {
     const size_t buffer_size = len + 1;
-    SmallBufferWithHeapFallback<PREF_BUFFER_SIZE> buffer_alloc(buffer_size);
-    uint8_t *buffer = buffer_alloc.get();
+    if (buffer_size > PREF_MAX_BUFFER_SIZE)
+      return false;
+    uint8_t buffer[PREF_MAX_BUFFER_SIZE];
 
     for (size_t i = 0; i < buffer_size; i++) {
-      uint32_t j = offset + i;
+      uint32_t j = this->offset + i;
       if (j >= RP2040_FLASH_STORAGE_SIZE)
         return false;
       buffer[i] = s_flash_storage[j];
     }
 
-    uint8_t crc = calculate_crc(buffer, buffer + len, type);
+    uint8_t crc = calculate_crc(buffer, buffer + len, this->type);
     if (buffer[len] != crc) {
       return false;
     }

esphome/components/serial_proxy/__init__.py

@@ -0,0 +1,62 @@
+"""
+Serial Proxy component for ESPHome.
+
+WARNING: This component is EXPERIMENTAL. The API (both Python configuration
+and C++ interfaces) may change at any time without following the normal
+breaking changes policy. Use at your own risk.
+
+Once the API is considered stable, this warning will be removed.
+
+Provides a proxy to/from a serial interface on the ESPHome device, allowing
+Home Assistant to connect to the serial port and send/receive data to/from
+an arbitrary serial device.
+"""
+
+from esphome import pins
+import esphome.codegen as cg
+from esphome.components import uart
+import esphome.config_validation as cv
+from esphome.const import CONF_ID
+
+CODEOWNERS = ["@kbx81"]
+DEPENDENCIES = ["api", "uart"]
+
+MULTI_CONF = True
+
+serial_proxy_ns = cg.esphome_ns.namespace("serial_proxy")
+SerialProxy = serial_proxy_ns.class_("SerialProxy", cg.Component, uart.UARTDevice)
+
+CONF_RTS_PIN = "rts_pin"
+CONF_DTR_PIN = "dtr_pin"
+
+
+CONFIG_SCHEMA = (
+    cv.Schema(
+        {
+            cv.GenerateID(): cv.declare_id(SerialProxy),
+            cv.Optional(CONF_RTS_PIN): pins.gpio_output_pin_schema,
+            cv.Optional(CONF_DTR_PIN): pins.gpio_output_pin_schema,
+        }
+    )
+    .extend(cv.COMPONENT_SCHEMA)
+    .extend(uart.UART_DEVICE_SCHEMA)
+)
+
+
+async def to_code(config):
+    var = cg.new_Pvariable(config[CONF_ID])
+    await cg.register_component(var, config)
+    await uart.register_uart_device(var, config)
+    cg.add(cg.App.register_serial_proxy(var))
+    cg.add_define("USE_SERIAL_PROXY")
+
+    if CONF_RTS_PIN in config:
+        rts_pin = await cg.gpio_pin_expression(config[CONF_RTS_PIN])
+        cg.add(var.set_rts_pin(rts_pin))
+
+    if CONF_DTR_PIN in config:
+        dtr_pin = await cg.gpio_pin_expression(config[CONF_DTR_PIN])
+        cg.add(var.set_dtr_pin(dtr_pin))
+
+    # Request UART to wake the main loop when data arrives for low-latency processing
+    uart.request_wake_loop_on_rx()

esphome/components/serial_proxy/serial_proxy.cpp

@@ -0,0 +1,131 @@
+#include "serial_proxy.h"
+
+#ifdef USE_SERIAL_PROXY
+
+#include "esphome/core/log.h"
+
+#ifdef USE_API
+#include "esphome/components/api/api_server.h"
+#endif
+
+namespace esphome::serial_proxy {
+
+static const char *const TAG = "serial_proxy";
+
+void SerialProxy::setup() {
+  // Set up modem control pins if configured
+  if (this->rts_pin_ != nullptr) {
+    this->rts_pin_->setup();
+    this->rts_pin_->digital_write(this->rts_state_);
+  }
+  if (this->dtr_pin_ != nullptr) {
+    this->dtr_pin_->setup();
+    this->dtr_pin_->digital_write(this->dtr_state_);
+  }
+}
+
+void SerialProxy::loop() {
+  // Read available data from UART and forward to API clients
+  size_t available = this->available();
+  if (available == 0)
+    return;
+
+  // Read in chunks up to SERIAL_PROXY_MAX_READ_SIZE
+  uint8_t buffer[SERIAL_PROXY_MAX_READ_SIZE];
+  size_t to_read = std::min(available, sizeof(buffer));
+
+  if (!this->read_array(buffer, to_read))
+    return;
+
+#ifdef USE_API
+  if (api::global_api_server != nullptr) {
+    api::global_api_server->send_serial_proxy_data(this->instance_index_, buffer, to_read);
+  }
+#endif
+}
+
+void SerialProxy::dump_config() {
+  ESP_LOGCONFIG(TAG,
+                "Serial Proxy [%u]:\n"
+                "  RTS Pin: %s\n"
+                "  DTR Pin: %s",
+                this->instance_index_, this->rts_pin_ != nullptr ? "configured" : "not configured",
+                this->dtr_pin_ != nullptr ? "configured" : "not configured");
+}
+
+void SerialProxy::configure(uint32_t baudrate, bool flow_control, uint8_t parity, uint8_t stop_bits,
+                            uint8_t data_size) {
+  ESP_LOGD(TAG, "Configuring serial proxy [%u]: baud=%u, flow_ctrl=%s, parity=%u, stop=%u, data=%u",
+           this->instance_index_, baudrate, YESNO(flow_control), parity, stop_bits, data_size);
+
+  auto *uart_comp = this->parent_;
+  if (uart_comp == nullptr) {
+    ESP_LOGE(TAG, "UART component not available");
+    return;
+  }
+
+  // Apply UART parameters
+  uart_comp->set_baud_rate(baudrate);
+  uart_comp->set_stop_bits(stop_bits);
+  uart_comp->set_data_bits(data_size);
+
+  // Map parity enum to UARTParityOptions
+  switch (parity) {
+    case 0:
+      uart_comp->set_parity(uart::UART_CONFIG_PARITY_NONE);
+      break;
+    case 1:
+      uart_comp->set_parity(uart::UART_CONFIG_PARITY_EVEN);
+      break;
+    case 2:
+      uart_comp->set_parity(uart::UART_CONFIG_PARITY_ODD);
+      break;
+    default:
+      ESP_LOGW(TAG, "Unknown parity value: %u, using NONE", parity);
+      uart_comp->set_parity(uart::UART_CONFIG_PARITY_NONE);
+      break;
+  }
+
+    // Apply the new settings
+    // load_settings() is available on ESP8266 and ESP32 platforms
+#if defined(USE_ESP8266) || defined(USE_ESP32)
+  uart_comp->load_settings(true);
+#endif
+
+  // Note: Hardware flow control configuration is stored but not yet applied
+  // to the UART hardware - this requires additional platform support
+  (void) flow_control;
+}
+
+void SerialProxy::write(const uint8_t *data, size_t len) {
+  if (data == nullptr || len == 0)
+    return;
+  this->write_array(data, len);
+}
+
+void SerialProxy::set_modem_pins(bool rts, bool dtr) {
+  ESP_LOGV(TAG, "Setting modem pins [%u]: RTS=%s, DTR=%s", this->instance_index_, ONOFF(rts), ONOFF(dtr));
+
+  if (this->rts_pin_ != nullptr) {
+    this->rts_state_ = rts;
+    this->rts_pin_->digital_write(rts);
+  }
+  if (this->dtr_pin_ != nullptr) {
+    this->dtr_state_ = dtr;
+    this->dtr_pin_->digital_write(dtr);
+  }
+}
+
+void SerialProxy::get_modem_pins(bool &rts, bool &dtr) const {
+  rts = this->rts_state_;
+  dtr = this->dtr_state_;
+}
+
+void SerialProxy::flush_port() {
+  ESP_LOGV(TAG, "Flushing serial proxy [%u]", this->instance_index_);
+  this->flush();
+}
+
+}  // namespace esphome::serial_proxy
+
+#endif  // USE_SERIAL_PROXY

esphome/components/serial_proxy/serial_proxy.h

@@ -0,0 +1,80 @@
+#pragma once
+
+// WARNING: This component is EXPERIMENTAL. The API may change at any time
+// without following the normal breaking changes policy. Use at your own risk.
+// Once the API is considered stable, this warning will be removed.
+
+#include "esphome/core/defines.h"
+
+#ifdef USE_SERIAL_PROXY
+
+#include "esphome/core/component.h"
+#include "esphome/core/hal.h"
+#include "esphome/components/uart/uart.h"
+
+namespace esphome::serial_proxy {
+
+/// Maximum bytes to read from UART in a single loop iteration
+static constexpr size_t SERIAL_PROXY_MAX_READ_SIZE = 256;
+
+class SerialProxy : public uart::UARTDevice, public Component {
+ public:
+  void setup() override;
+  void loop() override;
+  void dump_config() override;
+  float get_setup_priority() const override { return setup_priority::AFTER_CONNECTION; }
+
+  /// Get the instance index (position in Application's serial_proxies_ vector)
+  uint32_t get_instance_index() const { return this->instance_index_; }
+
+  /// Set the instance index (called by Application::register_serial_proxy)
+  void set_instance_index(uint32_t index) { this->instance_index_ = index; }
+
+  /// Configure UART parameters and apply them
+  /// @param baudrate Baud rate in bits per second
+  /// @param flow_control True to enable hardware flow control
+  /// @param parity Parity setting (0=none, 1=even, 2=odd)
+  /// @param stop_bits Number of stop bits (1 or 2)
+  /// @param data_size Number of data bits (5-8)
+  void configure(uint32_t baudrate, bool flow_control, uint8_t parity, uint8_t stop_bits, uint8_t data_size);
+
+  /// Write data to the serial device
+  /// @param data Pointer to data buffer
+  /// @param len Number of bytes to write
+  void write(const uint8_t *data, size_t len);
+
+  /// Set modem pin states (RTS and DTR)
+  /// @param rts Desired RTS pin state
+  /// @param dtr Desired DTR pin state
+  void set_modem_pins(bool rts, bool dtr);
+
+  /// Get current modem pin states
+  /// @param[out] rts Current RTS pin state
+  /// @param[out] dtr Current DTR pin state
+  void get_modem_pins(bool &rts, bool &dtr) const;
+
+  /// Flush the serial port (block until all TX data is sent)
+  void flush_port();
+
+  /// Set the RTS GPIO pin (from YAML configuration)
+  void set_rts_pin(GPIOPin *pin) { this->rts_pin_ = pin; }
+
+  /// Set the DTR GPIO pin (from YAML configuration)
+  void set_dtr_pin(GPIOPin *pin) { this->dtr_pin_ = pin; }
+
+ protected:
+  /// Instance index for identifying this proxy in API messages
+  uint32_t instance_index_{0};
+
+  /// Optional GPIO pins for modem control
+  GPIOPin *rts_pin_{nullptr};
+  GPIOPin *dtr_pin_{nullptr};
+
+  /// Current modem pin states
+  bool rts_state_{false};
+  bool dtr_state_{false};
+};
+
+}  // namespace esphome::serial_proxy
+
+#endif  // USE_SERIAL_PROXY

esphome/components/socket/bsd_sockets_impl.cpp

@@ -16,19 +16,13 @@ namespace esphome::socket {
 
 class BSDSocketImpl final : public Socket {
  public:
-  BSDSocketImpl(int fd, bool monitor_loop = false) : fd_(fd) {
-#ifdef USE_SOCKET_SELECT_SUPPORT
+  BSDSocketImpl(int fd, bool monitor_loop = false) {
+    this->fd_ = fd;
     // Register new socket with the application for select() if monitoring requested
     if (monitor_loop && this->fd_ >= 0) {
       // Only set loop_monitored_ to true if registration succeeds
       this->loop_monitored_ = App.register_socket_fd(this->fd_);
-    } else {
-      this->loop_monitored_ = false;
     }
-#else
-    // Without select support, ignore monitor_loop parameter
-    (void) monitor_loop;
-#endif
   }
   ~BSDSocketImpl() override {
     if (!this->closed_) {
@@ -52,12 +46,10 @@ class BSDSocketImpl final : public Socket {
   int bind(const struct sockaddr *addr, socklen_t addrlen) override { return ::bind(this->fd_, addr, addrlen); }
   int close() override {
     if (!this->closed_) {
-#ifdef USE_SOCKET_SELECT_SUPPORT
       // Unregister from select() before closing if monitored
       if (this->loop_monitored_) {
         App.unregister_socket_fd(this->fd_);
       }
-#endif
       int ret = ::close(this->fd_);
       this->closed_ = true;
       return ret;
@@ -130,23 +122,6 @@ class BSDSocketImpl final : public Socket {
     ::fcntl(this->fd_, F_SETFL, fl);
     return 0;
   }
-
-  int get_fd() const override { return this->fd_; }
-
-#ifdef USE_SOCKET_SELECT_SUPPORT
-  bool ready() const override {
-    if (!this->loop_monitored_)
-      return true;
-    return App.is_socket_ready(this->fd_);
-  }
-#endif
-
- protected:
-  int fd_;
-  bool closed_{false};
-#ifdef USE_SOCKET_SELECT_SUPPORT
-  bool loop_monitored_{false};
-#endif
 };
 
 // Helper to create a socket with optional monitoring

esphome/components/socket/lwip_raw_tcp_impl.cpp

@@ -452,6 +452,8 @@ class LWIPRawImpl : public Socket {
     errno = ENOSYS;
     return -1;
   }
+  bool ready() const override { return this->rx_buf_ != nullptr || this->rx_closed_ || this->pcb_ == nullptr; }
+
   int setblocking(bool blocking) final {
     if (pcb_ == nullptr) {
       errno = ECONNRESET;
@@ -576,6 +578,8 @@ class LWIPRawListenImpl final : public LWIPRawImpl {
     tcp_err(pcb_, LWIPRawImpl::s_err_fn);  // Use base class error handler
   }
 
+  bool ready() const override { return this->accepted_socket_count_ > 0; }
+
   std::unique_ptr<Socket> accept(struct sockaddr *addr, socklen_t *addrlen) override {
     if (pcb_ == nullptr) {
       errno = EBADF;

esphome/components/socket/lwip_sockets_impl.cpp

@@ -11,19 +11,13 @@ namespace esphome::socket {
 
 class LwIPSocketImpl final : public Socket {
  public:
-  LwIPSocketImpl(int fd, bool monitor_loop = false) : fd_(fd) {
-#ifdef USE_SOCKET_SELECT_SUPPORT
+  LwIPSocketImpl(int fd, bool monitor_loop = false) {
+    this->fd_ = fd;
     // Register new socket with the application for select() if monitoring requested
     if (monitor_loop && this->fd_ >= 0) {
       // Only set loop_monitored_ to true if registration succeeds
       this->loop_monitored_ = App.register_socket_fd(this->fd_);
-    } else {
-      this->loop_monitored_ = false;
     }
-#else
-    // Without select support, ignore monitor_loop parameter
-    (void) monitor_loop;
-#endif
   }
   ~LwIPSocketImpl() override {
     if (!this->closed_) {
@@ -49,12 +43,10 @@ class LwIPSocketImpl final : public Socket {
   int bind(const struct sockaddr *addr, socklen_t addrlen) override { return lwip_bind(this->fd_, addr, addrlen); }
   int close() override {
     if (!this->closed_) {
-#ifdef USE_SOCKET_SELECT_SUPPORT
       // Unregister from select() before closing if monitored
       if (this->loop_monitored_) {
         App.unregister_socket_fd(this->fd_);
       }
-#endif
       int ret = lwip_close(this->fd_);
       this->closed_ = true;
       return ret;
@@ -97,23 +89,6 @@ class LwIPSocketImpl final : public Socket {
     lwip_fcntl(this->fd_, F_SETFL, fl);
     return 0;
   }
-
-  int get_fd() const override { return this->fd_; }
-
-#ifdef USE_SOCKET_SELECT_SUPPORT
-  bool ready() const override {
-    if (!this->loop_monitored_)
-      return true;
-    return App.is_socket_ready(this->fd_);
-  }
-#endif
-
- protected:
-  int fd_;
-  bool closed_{false};
-#ifdef USE_SOCKET_SELECT_SUPPORT
-  bool loop_monitored_{false};
-#endif
 };
 
 // Helper to create a socket with optional monitoring

esphome/components/socket/socket.cpp

@@ -10,6 +10,10 @@ namespace esphome::socket {
 
 Socket::~Socket() {}
 
+#ifdef USE_SOCKET_SELECT_SUPPORT
+bool Socket::ready() const { return !this->loop_monitored_ || App.is_socket_ready_(this->fd_); }
+#endif
+
 // Platform-specific inet_ntop wrappers
 #if defined(USE_SOCKET_IMPL_LWIP_TCP)
 // LWIP raw TCP (ESP8266) uses inet_ntoa_r which takes struct by value

esphome/components/socket/socket.h

@@ -63,13 +63,29 @@ class Socket {
   virtual int setblocking(bool blocking) = 0;
   virtual int loop() { return 0; };
 
-  /// Get the underlying file descriptor (returns -1 if not supported)
-  virtual int get_fd() const { return -1; }
+    /// Get the underlying file descriptor (returns -1 if not supported)
+    /// Non-virtual: only one socket implementation is active per build.
+#ifdef USE_SOCKET_SELECT_SUPPORT
+  int get_fd() const { return this->fd_; }
+#else
+  int get_fd() const { return -1; }
+#endif
 
   /// Check if socket has data ready to read
-  /// For loop-monitored sockets, checks with the Application's select() results
-  /// For non-monitored sockets, always returns true (assumes data may be available)
+  /// For select()-based sockets: non-virtual, checks Application's select() results
+  /// For LWIP raw TCP sockets: virtual, checks internal buffer state
+#ifdef USE_SOCKET_SELECT_SUPPORT
+  bool ready() const;
+#else
   virtual bool ready() const { return true; }
+#endif
+
+ protected:
+#ifdef USE_SOCKET_SELECT_SUPPORT
+  int fd_{-1};
+  bool closed_{false};
+  bool loop_monitored_{false};
+#endif
 };
 
 /// Create a socket of the given domain, type and protocol.

esphome/components/web_server/web_server.h

@@ -112,10 +112,10 @@ class DeferredUpdateEventSource : public AsyncEventSource {
   /*
     This class holds a pointer to the source component that wants to publish a state event, and a pointer to a function
     that will lazily generate that event.  The two pointers allow dedup in the deferred queue if multiple publishes for
-    the same component are backed up, and take up only 8 bytes of memory.  The entry in the deferred queue (a
-    std::vector) is the DeferredEvent instance itself (not a pointer to one elsewhere in heap) so still only 8 bytes per
-    entry (and no heap fragmentation).  Even 100 backed up events (you'd have to have at least 100 sensors publishing
-    because of dedup) would take up only 0.8 kB.
+    the same component are backed up, and take up only two pointers of memory.  The entry in the deferred queue (a
+    std::vector) is the DeferredEvent instance itself (not a pointer to one elsewhere in heap) so still only two
+    pointers per entry (and no heap fragmentation).  Even 100 backed up events (you'd have to have at least 100 sensors
+    publishing because of dedup) would take up only 0.8 kB.
   */
   struct DeferredEvent {
     friend class DeferredUpdateEventSource;
@@ -130,7 +130,9 @@ class DeferredUpdateEventSource : public AsyncEventSource {
     bool operator==(const DeferredEvent &test) const {
       return (source_ == test.source_ && message_generator_ == test.message_generator_);
     }
-  } __attribute__((packed));
+  };
+  static_assert(sizeof(DeferredEvent) == sizeof(void *) + sizeof(message_generator_t *),
+                "DeferredEvent should have no padding");
 
  protected:
   // surface a couple methods from the base class

esphome/components/web_server_idf/multipart.cpp

@@ -54,14 +54,15 @@ size_t MultipartReader::parse(const char *data, size_t len) {
 
 void MultipartReader::process_header_(const char *value, size_t length) {
   // Process the completed header (field + value pair)
-  std::string value_str(value, length);
+  const char *field = current_header_field_.c_str();
+  size_t field_len = current_header_field_.length();
 
-  if (str_startswith_case_insensitive(current_header_field_, "content-disposition")) {
+  if (str_startswith_case_insensitive(field, field_len, "content-disposition")) {
     // Parse name and filename from Content-Disposition
-    current_part_.name = extract_header_param(value_str, "name");
-    current_part_.filename = extract_header_param(value_str, "filename");
-  } else if (str_startswith_case_insensitive(current_header_field_, "content-type")) {
-    current_part_.content_type = str_trim(value_str);
+    extract_header_param(value, length, "name", current_part_.name);
+    extract_header_param(value, length, "filename", current_part_.filename);
+  } else if (str_startswith_case_insensitive(field, field_len, "content-type")) {
+    str_trim(value, length, current_part_.content_type);
   }
 
   // Clear field for next header
@@ -107,25 +108,29 @@ int MultipartReader::on_part_data_end(multipart_parser *parser) {
 // ========== Utility Functions ==========
 
 // Case-insensitive string prefix check
-bool str_startswith_case_insensitive(const std::string &str, const std::string &prefix) {
-  if (str.length() < prefix.length()) {
+bool str_startswith_case_insensitive(const char *str, size_t str_len, const char *prefix) {
+  size_t prefix_len = strlen(prefix);
+  if (str_len < prefix_len) {
     return false;
   }
-  return str_ncmp_ci(str.c_str(), prefix.c_str(), prefix.length());
+  return str_ncmp_ci(str, prefix, prefix_len);
 }
 
 // Extract a parameter value from a header line
 // Handles both quoted and unquoted values
-std::string extract_header_param(const std::string &header, const std::string &param) {
+// Assigns to out if found, clears out otherwise
+void extract_header_param(const char *header, size_t header_len, const char *param, std::string &out) {
+  size_t param_len = strlen(param);
   size_t search_pos = 0;
 
-  while (search_pos < header.length()) {
+  while (search_pos < header_len) {
     // Look for param name
-    const char *found = stristr(header.c_str() + search_pos, param.c_str());
+    const char *found = strcasestr_n(header + search_pos, header_len - search_pos, param);
     if (!found) {
-      return "";
+      out.clear();
+      return;
     }
-    size_t pos = found - header.c_str();
+    size_t pos = found - header;
 
     // Check if this is a word boundary (not part of another parameter)
     if (pos > 0 && header[pos - 1] != ' ' && header[pos - 1] != ';' && header[pos - 1] != '\t') {
@@ -134,14 +139,14 @@ std::string extract_header_param(const std::string &header, const std::string &p
     }
 
     // Move past param name
-    pos += param.length();
+    pos += param_len;
 
     // Skip whitespace and find '='
-    while (pos < header.length() && (header[pos] == ' ' || header[pos] == '\t')) {
+    while (pos < header_len && (header[pos] == ' ' || header[pos] == '\t')) {
       pos++;
     }
 
-    if (pos >= header.length() || header[pos] != '=') {
+    if (pos >= header_len || header[pos] != '=') {
       search_pos = pos;
       continue;
     }
@@ -149,36 +154,39 @@ std::string extract_header_param(const std::string &header, const std::string &p
     pos++;  // Skip '='
 
     // Skip whitespace after '='
-    while (pos < header.length() && (header[pos] == ' ' || header[pos] == '\t')) {
+    while (pos < header_len && (header[pos] == ' ' || header[pos] == '\t')) {
       pos++;
     }
 
-    if (pos >= header.length()) {
-      return "";
+    if (pos >= header_len) {
+      out.clear();
+      return;
     }
 
     // Check if value is quoted
     if (header[pos] == '"') {
       pos++;
-      size_t end = header.find('"', pos);
-      if (end != std::string::npos) {
-        return header.substr(pos, end - pos);
+      const char *end = static_cast<const char *>(memchr(header + pos, '"', header_len - pos));
+      if (end) {
+        out.assign(header + pos, end - (header + pos));
+        return;
       }
       // Malformed - no closing quote
-      return "";
+      out.clear();
+      return;
     }
 
     // Unquoted value - find the end (semicolon, comma, or end of string)
     size_t end = pos;
-    while (end < header.length() && header[end] != ';' && header[end] != ',' && header[end] != ' ' &&
-           header[end] != '\t') {
+    while (end < header_len && header[end] != ';' && header[end] != ',' && header[end] != ' ' && header[end] != '\t') {
       end++;
     }
 
-    return header.substr(pos, end - pos);
+    out.assign(header + pos, end - pos);
+    return;
   }
 
-  return "";
+  out.clear();
 }
 
 // Parse boundary from Content-Type header
@@ -189,13 +197,15 @@ bool parse_multipart_boundary(const char *content_type, const char **boundary_st
     return false;
   }
 
+  size_t content_type_len = strlen(content_type);
+
   // Check for multipart/form-data (case-insensitive)
-  if (!stristr(content_type, "multipart/form-data")) {
+  if (!strcasestr_n(content_type, content_type_len, "multipart/form-data")) {
     return false;
   }
 
   // Look for boundary parameter
-  const char *b = stristr(content_type, "boundary=");
+  const char *b = strcasestr_n(content_type, content_type_len, "boundary=");
   if (!b) {
     return false;
   }
@@ -238,14 +248,15 @@ bool parse_multipart_boundary(const char *content_type, const char **boundary_st
   return true;
 }
 
-// Trim whitespace from both ends of a string
-std::string str_trim(const std::string &str) {
-  size_t start = str.find_first_not_of(" \t\r\n");
-  if (start == std::string::npos) {
-    return "";
-  }
-  size_t end = str.find_last_not_of(" \t\r\n");
-  return str.substr(start, end - start + 1);
+// Trim whitespace from both ends, assign result to out
+void str_trim(const char *str, size_t len, std::string &out) {
+  const char *start = str;
+  const char *end = str + len;
+  while (start < end && (*start == ' ' || *start == '\t' || *start == '\r' || *start == '\n'))
+    start++;
+  while (end > start && (end[-1] == ' ' || end[-1] == '\t' || end[-1] == '\r' || end[-1] == '\n'))
+    end--;
+  out.assign(start, end - start);
 }
 
 }  // namespace esphome::web_server_idf

esphome/components/web_server_idf/multipart.h

@@ -66,19 +66,20 @@ class MultipartReader {
 // ========== Utility Functions ==========
 
 // Case-insensitive string prefix check
-bool str_startswith_case_insensitive(const std::string &str, const std::string &prefix);
+bool str_startswith_case_insensitive(const char *str, size_t str_len, const char *prefix);
 
 // Extract a parameter value from a header line
 // Handles both quoted and unquoted values
-std::string extract_header_param(const std::string &header, const std::string &param);
+// Assigns to out if found, clears out otherwise
+void extract_header_param(const char *header, size_t header_len, const char *param, std::string &out);
 
 // Parse boundary from Content-Type header
 // Returns true if boundary found, false otherwise
 // boundary_start and boundary_len will point to the boundary value
 bool parse_multipart_boundary(const char *content_type, const char **boundary_start, size_t *boundary_len);
 
-// Trim whitespace from both ends of a string
-std::string str_trim(const std::string &str);
+// Trim whitespace from both ends, assign result to out
+void str_trim(const char *str, size_t len, std::string &out);
 
 }  // namespace esphome::web_server_idf
 #endif  // defined(USE_ESP32) && defined(USE_WEBSERVER_OTA)

esphome/components/web_server_idf/utils.cpp

@@ -98,8 +98,8 @@ bool str_ncmp_ci(const char *s1, const char *s2, size_t n) {
   return true;
 }
 
-// Case-insensitive string search (like strstr but case-insensitive)
-const char *stristr(const char *haystack, const char *needle) {
+// Bounded case-insensitive string search (like strcasestr but length-bounded)
+const char *strcasestr_n(const char *haystack, size_t haystack_len, const char *needle) {
   if (!haystack) {
     return nullptr;
   }
@@ -109,7 +109,12 @@ const char *stristr(const char *haystack, const char *needle) {
     return haystack;
   }
 
-  for (const char *p = haystack; *p; p++) {
+  if (haystack_len < needle_len) {
+    return nullptr;
+  }
+
+  const char *end = haystack + haystack_len - needle_len + 1;
+  for (const char *p = haystack; p < end; p++) {
     if (str_ncmp_ci(p, needle, needle_len)) {
       return p;
     }

esphome/components/web_server_idf/utils.h

@@ -25,8 +25,8 @@ inline bool char_equals_ci(char a, char b) { return ::tolower(a) == ::tolower(b)
 // Helper function for case-insensitive string region comparison
 bool str_ncmp_ci(const char *s1, const char *s2, size_t n);
 
-// Case-insensitive string search (like strstr but case-insensitive)
-const char *stristr(const char *haystack, const char *needle);
+// Bounded case-insensitive string search (like strcasestr but length-bounded)
+const char *strcasestr_n(const char *haystack, size_t haystack_len, const char *needle);
 
 }  // namespace esphome::web_server_idf
 #endif  // USE_ESP32

esphome/components/web_server_idf/web_server_idf.cpp

@@ -171,10 +171,11 @@ esp_err_t AsyncWebServer::request_post_handler(httpd_req_t *r) {
     const char *content_type_char = content_type.value().c_str();
 
     // Check most common case first
-    if (stristr(content_type_char, "application/x-www-form-urlencoded") != nullptr) {
+    size_t content_type_len = strlen(content_type_char);
+    if (strcasestr_n(content_type_char, content_type_len, "application/x-www-form-urlencoded") != nullptr) {
       // Normal form data - proceed with regular handling
 #ifdef USE_WEBSERVER_OTA
-    } else if (stristr(content_type_char, "multipart/form-data") != nullptr) {
+    } else if (strcasestr_n(content_type_char, content_type_len, "multipart/form-data") != nullptr) {
       auto *server = static_cast<AsyncWebServer *>(r->user_ctx);
       return server->handle_multipart_upload_(r, content_type_char);
 #endif
@@ -352,7 +353,26 @@ bool AsyncWebServerRequest::authenticate(const char *username, const char *passw
   esp_crypto_base64_encode(reinterpret_cast<uint8_t *>(digest), max_digest_len, &out,
                            reinterpret_cast<const uint8_t *>(user_info), user_info_len);
 
-  return strcmp(digest, auth_str + auth_prefix_len) == 0;
+  // Constant-time comparison to avoid timing side channels.
+  // No early return on length mismatch — the length difference is folded
+  // into the accumulator so any mismatch is rejected.
+  const char *provided = auth_str + auth_prefix_len;
+  size_t digest_len = out;  // length from esp_crypto_base64_encode
+  // Derive provided_len from the already-sized std::string rather than
+  // rescanning with strlen (avoids attacker-controlled scan length).
+  size_t provided_len = auth.value().size() - auth_prefix_len;
+  // Use full-width XOR so any bit difference in the lengths is preserved
+  // (uint8_t truncation would miss differences in higher bytes, e.g.
+  // digest_len vs digest_len + 256).
+  volatile size_t result = digest_len ^ provided_len;
+  // Iterate over the expected digest length only — the full-width length
+  // XOR above already rejects any length mismatch, and bounding the loop
+  // prevents a long Authorization header from forcing extra work.
+  for (size_t i = 0; i < digest_len; i++) {
+    char provided_ch = (i < provided_len) ? provided[i] : 0;
+    result |= static_cast<uint8_t>(digest[i] ^ provided_ch);
+  }
+  return result == 0;
 }
 
 void AsyncWebServerRequest::requestAuthentication(const char *realm) const {
@@ -862,12 +882,12 @@ esp_err_t AsyncWebServer::handle_multipart_upload_(httpd_req_t *r, const char *c
     }
   });
 
-  // Process data - use stack buffer to avoid heap allocation
-  char buffer[MULTIPART_CHUNK_SIZE];
+  // Use heap buffer - 1460 bytes is too large for the httpd task stack
+  auto buffer = std::make_unique<char[]>(MULTIPART_CHUNK_SIZE);
   size_t bytes_since_yield = 0;
 
   for (size_t remaining = r->content_len; remaining > 0;) {
-    int recv_len = httpd_req_recv(r, buffer, std::min(remaining, MULTIPART_CHUNK_SIZE));
+    int recv_len = httpd_req_recv(r, buffer.get(), std::min(remaining, MULTIPART_CHUNK_SIZE));
 
     if (recv_len <= 0) {
       httpd_resp_send_err(r, recv_len == HTTPD_SOCK_ERR_TIMEOUT ? HTTPD_408_REQ_TIMEOUT : HTTPD_400_BAD_REQUEST,
@@ -875,7 +895,7 @@ esp_err_t AsyncWebServer::handle_multipart_upload_(httpd_req_t *r, const char *c
       return recv_len == HTTPD_SOCK_ERR_TIMEOUT ? ESP_ERR_TIMEOUT : ESP_FAIL;
     }
 
-    if (reader->parse(buffer, recv_len) != static_cast<size_t>(recv_len)) {
+    if (reader->parse(buffer.get(), recv_len) != static_cast<size_t>(recv_len)) {
       ESP_LOGW(TAG, "Multipart parser error");
       httpd_resp_send_err(r, HTTPD_400_BAD_REQUEST, nullptr);
       return ESP_FAIL;

esphome/components/web_server_idf/web_server_idf.h

@@ -259,9 +259,9 @@ using message_generator_t = std::string(esphome::web_server::WebServer *, void *
 /*
   This class holds a pointer to the source component that wants to publish a state event, and a pointer to a function
   that will lazily generate that event.  The two pointers allow dedup in the deferred queue if multiple publishes for
-  the same component are backed up, and take up only 8 bytes of memory.  The entry in the deferred queue (a
-  std::vector) is the DeferredEvent instance itself (not a pointer to one elsewhere in heap) so still only 8 bytes per
-  entry (and no heap fragmentation).  Even 100 backed up events (you'd have to have at least 100 sensors publishing
+  the same component are backed up, and take up only two pointers of memory.  The entry in the deferred queue (a
+  std::vector) is the DeferredEvent instance itself (not a pointer to one elsewhere in heap) so still only two pointers
+  per entry (and no heap fragmentation).  Even 100 backed up events (you'd have to have at least 100 sensors publishing
   because of dedup) would take up only 0.8 kB.
 */
 struct DeferredEvent {
@@ -277,7 +277,9 @@ struct DeferredEvent {
   bool operator==(const DeferredEvent &test) const {
     return (source_ == test.source_ && message_generator_ == test.message_generator_);
   }
-} __attribute__((packed));
+};
+static_assert(sizeof(DeferredEvent) == sizeof(void *) + sizeof(message_generator_t *),
+              "DeferredEvent should have no padding");
 
 class AsyncEventSourceResponse {
   friend class AsyncEventSource;

esphome/components/wifi/wifi_component.cpp

@@ -20,6 +20,7 @@
 #endif
 
 #include <algorithm>
+#include <new>
 #include <utility>
 #include "lwip/dns.h"
 #include "lwip/err.h"
@@ -47,6 +48,69 @@ namespace esphome::wifi {
 
 static const char *const TAG = "wifi";
 
+// CompactString implementation
+CompactString::CompactString(const char *str, size_t len) {
+  if (len > MAX_LENGTH) {
+    len = MAX_LENGTH;  // Clamp to max valid length
+  }
+
+  this->length_ = len;
+  if (len <= INLINE_CAPACITY) {
+    // Store inline with null terminator
+    this->is_heap_ = 0;
+    if (len > 0) {
+      std::memcpy(this->storage_, str, len);
+    }
+    this->storage_[len] = '\0';
+  } else {
+    // Heap allocate with null terminator
+    this->is_heap_ = 1;
+    char *heap_data = new char[len + 1];  // NOLINT(cppcoreguidelines-owning-memory)
+    std::memcpy(heap_data, str, len);
+    heap_data[len] = '\0';
+    this->set_heap_ptr_(heap_data);
+  }
+}
+
+CompactString::CompactString(const CompactString &other) : CompactString(other.data(), other.size()) {}
+
+CompactString &CompactString::operator=(const CompactString &other) {
+  if (this != &other) {
+    this->~CompactString();
+    new (this) CompactString(other);
+  }
+  return *this;
+}
+
+CompactString::CompactString(CompactString &&other) noexcept : length_(other.length_), is_heap_(other.is_heap_) {
+  // Copy full storage (includes null terminator for inline, or pointer for heap)
+  std::memcpy(this->storage_, other.storage_, INLINE_CAPACITY + 1);
+  other.length_ = 0;
+  other.is_heap_ = 0;
+  other.storage_[0] = '\0';
+}
+
+CompactString &CompactString::operator=(CompactString &&other) noexcept {
+  if (this != &other) {
+    this->~CompactString();
+    new (this) CompactString(std::move(other));
+  }
+  return *this;
+}
+
+CompactString::~CompactString() {
+  if (this->is_heap_) {
+    delete[] this->get_heap_ptr_();  // NOLINT(cppcoreguidelines-owning-memory)
+  }
+}
+
+bool CompactString::operator==(const CompactString &other) const {
+  return this->size() == other.size() && std::memcmp(this->data(), other.data(), this->size()) == 0;
+}
+bool CompactString::operator==(const StringRef &other) const {
+  return this->size() == other.size() && std::memcmp(this->data(), other.c_str(), this->size()) == 0;
+}
+
 /// WiFi Retry Logic - Priority-Based BSSID Selection
 ///
 /// The WiFi component uses a state machine with priority degradation to handle connection failures
@@ -349,18 +413,18 @@ bool WiFiComponent::needs_scan_results_() const {
   return this->scan_result_.empty() || !this->scan_result_[0].get_matches();
 }
 
-bool WiFiComponent::ssid_was_seen_in_scan_(const std::string &ssid) const {
+bool WiFiComponent::ssid_was_seen_in_scan_(const CompactString &ssid) const {
   // Check if this SSID is configured as hidden
   // If explicitly marked hidden, we should always try hidden mode regardless of scan results
   for (const auto &conf : this->sta_) {
-    if (conf.get_ssid() == ssid && conf.get_hidden()) {
+    if (conf.ssid_ == ssid && conf.get_hidden()) {
       return false;  // Treat as not seen - force hidden mode attempt
     }
   }
 
   // Otherwise, check if we saw it in scan results
   for (const auto &scan : this->scan_result_) {
-    if (scan.get_ssid() == ssid) {
+    if (scan.ssid_ == ssid) {
       return true;
     }
   }
@@ -409,14 +473,14 @@ bool WiFiComponent::matches_configured_network_(const char *ssid, const uint8_t
       continue;
     }
     // For BSSID-only configs (empty SSID), match by BSSID
-    if (sta.get_ssid().empty()) {
+    if (sta.ssid_.empty()) {
       if (sta.has_bssid() && std::memcmp(sta.get_bssid().data(), bssid, 6) == 0) {
         return true;
       }
       continue;
     }
     // Match by SSID
-    if (sta.get_ssid() == ssid) {
+    if (sta.ssid_ == ssid) {
       return true;
     }
   }
@@ -465,18 +529,18 @@ int8_t WiFiComponent::find_next_hidden_sta_(int8_t start_index) {
     if (!include_explicit_hidden && sta.get_hidden()) {
       int8_t first_non_hidden_idx = this->find_first_non_hidden_index_();
       if (first_non_hidden_idx < 0 || static_cast<int8_t>(i) < first_non_hidden_idx) {
-        ESP_LOGD(TAG, "Skipping " LOG_SECRET("'%s'") " (explicit hidden, already tried)", sta.get_ssid().c_str());
+        ESP_LOGD(TAG, "Skipping " LOG_SECRET("'%s'") " (explicit hidden, already tried)", sta.ssid_.c_str());
         continue;
       }
     }
 
     // In BLIND_RETRY mode, treat all networks as candidates
     // In SCAN_BASED mode, only retry networks that weren't seen in the scan
-    if (this->retry_hidden_mode_ == RetryHiddenMode::BLIND_RETRY || !this->ssid_was_seen_in_scan_(sta.get_ssid())) {
-      ESP_LOGD(TAG, "Hidden candidate " LOG_SECRET("'%s'") " at index %d", sta.get_ssid().c_str(), static_cast<int>(i));
+    if (this->retry_hidden_mode_ == RetryHiddenMode::BLIND_RETRY || !this->ssid_was_seen_in_scan_(sta.ssid_)) {
+      ESP_LOGD(TAG, "Hidden candidate " LOG_SECRET("'%s'") " at index %d", sta.ssid_.c_str(), static_cast<int>(i));
       return static_cast<int8_t>(i);
     }
-    ESP_LOGD(TAG, "Skipping hidden retry for visible network " LOG_SECRET("'%s'"), sta.get_ssid().c_str());
+    ESP_LOGD(TAG, "Skipping hidden retry for visible network " LOG_SECRET("'%s'"), sta.ssid_.c_str());
   }
   // No hidden SSIDs found
   return -1;
@@ -593,11 +657,11 @@ void WiFiComponent::start() {
     // Fast connect optimization: only use when we have saved BSSID+channel data
     // Without saved data, try first configured network or use normal flow
     if (loaded_fast_connect) {
-      ESP_LOGI(TAG, "Starting fast_connect (saved) " LOG_SECRET("'%s'"), params.get_ssid().c_str());
+      ESP_LOGI(TAG, "Starting fast_connect (saved) " LOG_SECRET("'%s'"), params.ssid_.c_str());
       this->start_connecting(params);
     } else if (!this->sta_.empty() && !this->sta_[0].get_hidden()) {
       // No saved data, but have configured networks - try first non-hidden network
-      ESP_LOGI(TAG, "Starting fast_connect (config) " LOG_SECRET("'%s'"), this->sta_[0].get_ssid().c_str());
+      ESP_LOGI(TAG, "Starting fast_connect (config) " LOG_SECRET("'%s'"), this->sta_[0].ssid_.c_str());
       this->selected_sta_index_ = 0;
       params = this->build_params_for_current_phase_();
       this->start_connecting(params);
@@ -827,7 +891,7 @@ void WiFiComponent::setup_ap_config_() {
   if (this->ap_setup_)
     return;
 
-  if (this->ap_.get_ssid().empty()) {
+  if (this->ap_.ssid_.empty()) {
     // Build AP SSID from app name without heap allocation
     // WiFi SSID max is 32 bytes, with MAC suffix we keep first 25 + last 7
     static constexpr size_t AP_SSID_MAX_LEN = 32;
@@ -863,7 +927,7 @@ void WiFiComponent::setup_ap_config_() {
                 "  AP SSID: '%s'\n"
                 "  AP Password: '%s'\n"
                 "  IP Address: %s",
-                this->ap_.get_ssid().c_str(), this->ap_.get_password().c_str(), this->wifi_soft_ap_ip().str_to(ip_buf));
+                this->ap_.ssid_.c_str(), this->ap_.password_.c_str(), this->wifi_soft_ap_ip().str_to(ip_buf));
 
 #ifdef USE_WIFI_MANUAL_IP
   auto manual_ip = this->ap_.get_manual_ip();
@@ -960,9 +1024,12 @@ WiFiAP WiFiComponent::get_sta() const {
   return config ? *config : WiFiAP{};
 }
 void WiFiComponent::save_wifi_sta(const std::string &ssid, const std::string &password) {
+  this->save_wifi_sta(ssid.c_str(), password.c_str());
+}
+void WiFiComponent::save_wifi_sta(const char *ssid, const char *password) {
   SavedWifiSettings save{};  // zero-initialized - all bytes set to \0, guaranteeing null termination
-  strncpy(save.ssid, ssid.c_str(), sizeof(save.ssid) - 1);              // max 32 chars, byte 32 remains \0
-  strncpy(save.password, password.c_str(), sizeof(save.password) - 1);  // max 64 chars, byte 64 remains \0
+  strncpy(save.ssid, ssid, sizeof(save.ssid) - 1);              // max 32 chars, byte 32 remains \0
+  strncpy(save.password, password, sizeof(save.password) - 1);  // max 64 chars, byte 64 remains \0
   this->pref_.save(&save);
   // ensure it's written immediately
   global_preferences->sync();
@@ -996,14 +1063,14 @@ void WiFiComponent::start_connecting(const WiFiAP &ap) {
 
   ESP_LOGI(TAG,
            "Connecting to " LOG_SECRET("'%s'") " " LOG_SECRET("(%s)") " (priority %d, attempt %u/%u in phase %s)...",
-           ap.get_ssid().c_str(), ap.has_bssid() ? bssid_s : LOG_STR_LITERAL("any"), priority, this->num_retried_ + 1,
+           ap.ssid_.c_str(), ap.has_bssid() ? bssid_s : LOG_STR_LITERAL("any"), priority, this->num_retried_ + 1,
            get_max_retries_for_phase(this->retry_phase_), LOG_STR_ARG(retry_phase_to_log_string(this->retry_phase_)));
 
 #ifdef ESPHOME_LOG_HAS_VERBOSE
   ESP_LOGV(TAG,
            "Connection Params:\n"
            "  SSID: '%s'",
-           ap.get_ssid().c_str());
+           ap.ssid_.c_str());
   if (ap.has_bssid()) {
     ESP_LOGV(TAG, "  BSSID: %s", bssid_s);
   } else {
@@ -1036,7 +1103,7 @@ void WiFiComponent::start_connecting(const WiFiAP &ap) {
              client_key_present ? "present" : "not present");
   } else {
 #endif
-    ESP_LOGV(TAG, "  Password: " LOG_SECRET("'%s'"), ap.get_password().c_str());
+    ESP_LOGV(TAG, "  Password: " LOG_SECRET("'%s'"), ap.password_.c_str());
 #ifdef USE_WIFI_WPA2_EAP
   }
 #endif
@@ -1411,7 +1478,7 @@ void WiFiComponent::check_connecting_finished(uint32_t now) {
     if (const WiFiAP *config = this->get_selected_sta_(); this->retry_phase_ == WiFiRetryPhase::RETRY_HIDDEN &&
                                                           config && !config->get_hidden() &&
                                                           this->scan_result_.empty()) {
-      ESP_LOGW(TAG, LOG_SECRET("'%s'") " should be marked hidden", config->get_ssid().c_str());
+      ESP_LOGW(TAG, LOG_SECRET("'%s'") " should be marked hidden", config->ssid_.c_str());
     }
     // Reset to initial phase on successful connection (don't log transition, just reset state)
     this->retry_phase_ = WiFiRetryPhase::INITIAL_CONNECT;
@@ -1825,11 +1892,11 @@ void WiFiComponent::log_and_adjust_priority_for_failed_connect_() {
   }
 
   // Get SSID for logging (use pointer to avoid copy)
-  const std::string *ssid = nullptr;
+  const char *ssid = nullptr;
   if (this->retry_phase_ == WiFiRetryPhase::SCAN_CONNECTING && !this->scan_result_.empty()) {
-    ssid = &this->scan_result_[0].get_ssid();
+    ssid = this->scan_result_[0].ssid_.c_str();
   } else if (const WiFiAP *config = this->get_selected_sta_()) {
-    ssid = &config->get_ssid();
+    ssid = config->ssid_.c_str();
   }
 
   // Only decrease priority on the last attempt for this phase
@@ -1849,8 +1916,8 @@ void WiFiComponent::log_and_adjust_priority_for_failed_connect_() {
   }
   char bssid_s[18];
   format_mac_addr_upper(failed_bssid.value().data(), bssid_s);
-  ESP_LOGD(TAG, "Failed " LOG_SECRET("'%s'") " " LOG_SECRET("(%s)") ", priority %d → %d",
-           ssid != nullptr ? ssid->c_str() : "", bssid_s, old_priority, new_priority);
+  ESP_LOGD(TAG, "Failed " LOG_SECRET("'%s'") " " LOG_SECRET("(%s)") ", priority %d → %d", ssid != nullptr ? ssid : "",
+           bssid_s, old_priority, new_priority);
 
   // After adjusting priority, check if all priorities are now at minimum
   // If so, clear the vector to save memory and reset for fresh start
@@ -2098,10 +2165,14 @@ void WiFiComponent::save_fast_connect_settings_() {
 }
 #endif
 
-void WiFiAP::set_ssid(const std::string &ssid) { this->ssid_ = ssid; }
+void WiFiAP::set_ssid(const std::string &ssid) { this->ssid_ = CompactString(ssid.c_str(), ssid.size()); }
+void WiFiAP::set_ssid(const char *ssid) { this->ssid_ = CompactString(ssid, strlen(ssid)); }
 void WiFiAP::set_bssid(const bssid_t &bssid) { this->bssid_ = bssid; }
 void WiFiAP::clear_bssid() { this->bssid_ = {}; }
-void WiFiAP::set_password(const std::string &password) { this->password_ = password; }
+void WiFiAP::set_password(const std::string &password) {
+  this->password_ = CompactString(password.c_str(), password.size());
+}
+void WiFiAP::set_password(const char *password) { this->password_ = CompactString(password, strlen(password)); }
 #ifdef USE_WIFI_WPA2_EAP
 void WiFiAP::set_eap(optional<EAPAuth> eap_auth) { this->eap_ = std::move(eap_auth); }
 #endif
@@ -2111,10 +2182,8 @@ void WiFiAP::clear_channel() { this->channel_ = 0; }
 void WiFiAP::set_manual_ip(optional<ManualIP> manual_ip) { this->manual_ip_ = manual_ip; }
 #endif
 void WiFiAP::set_hidden(bool hidden) { this->hidden_ = hidden; }
-const std::string &WiFiAP::get_ssid() const { return this->ssid_; }
 const bssid_t &WiFiAP::get_bssid() const { return this->bssid_; }
 bool WiFiAP::has_bssid() const { return this->bssid_ != bssid_t{}; }
-const std::string &WiFiAP::get_password() const { return this->password_; }
 #ifdef USE_WIFI_WPA2_EAP
 const optional<EAPAuth> &WiFiAP::get_eap() const { return this->eap_; }
 #endif
@@ -2125,12 +2194,12 @@ const optional<ManualIP> &WiFiAP::get_manual_ip() const { return this->manual_ip
 #endif
 bool WiFiAP::get_hidden() const { return this->hidden_; }
 
-WiFiScanResult::WiFiScanResult(const bssid_t &bssid, std::string ssid, uint8_t channel, int8_t rssi, bool with_auth,
-                               bool is_hidden)
+WiFiScanResult::WiFiScanResult(const bssid_t &bssid, const char *ssid, size_t ssid_len, uint8_t channel, int8_t rssi,
+                               bool with_auth, bool is_hidden)
     : bssid_(bssid),
       channel_(channel),
       rssi_(rssi),
-      ssid_(std::move(ssid)),
+      ssid_(ssid, ssid_len),
       with_auth_(with_auth),
       is_hidden_(is_hidden) {}
 bool WiFiScanResult::matches(const WiFiAP &config) const {
@@ -2139,9 +2208,9 @@ bool WiFiScanResult::matches(const WiFiAP &config) const {
     // don't match SSID
     if (!this->is_hidden_)
       return false;
-  } else if (!config.get_ssid().empty()) {
+  } else if (!config.ssid_.empty()) {
     // check if SSID matches
-    if (config.get_ssid() != this->ssid_)
+    if (this->ssid_ != config.ssid_)
       return false;
   } else {
     // network is configured without SSID - match other settings
@@ -2152,15 +2221,15 @@ bool WiFiScanResult::matches(const WiFiAP &config) const {
 
 #ifdef USE_WIFI_WPA2_EAP
   // BSSID requires auth but no PSK or EAP credentials given
-  if (this->with_auth_ && (config.get_password().empty() && !config.get_eap().has_value()))
+  if (this->with_auth_ && (config.password_.empty() && !config.get_eap().has_value()))
     return false;
 
   // BSSID does not require auth, but PSK or EAP credentials given
-  if (!this->with_auth_ && (!config.get_password().empty() || config.get_eap().has_value()))
+  if (!this->with_auth_ && (!config.password_.empty() || config.get_eap().has_value()))
     return false;
 #else
   // If PSK given, only match for networks with auth (and vice versa)
-  if (config.get_password().empty() == this->with_auth_)
+  if (config.password_.empty() == this->with_auth_)
     return false;
 #endif
 
@@ -2173,7 +2242,6 @@ bool WiFiScanResult::matches(const WiFiAP &config) const {
 bool WiFiScanResult::get_matches() const { return this->matches_; }
 void WiFiScanResult::set_matches(bool matches) { this->matches_ = matches; }
 const bssid_t &WiFiScanResult::get_bssid() const { return this->bssid_; }
-const std::string &WiFiScanResult::get_ssid() const { return this->ssid_; }
 uint8_t WiFiScanResult::get_channel() const { return this->channel_; }
 int8_t WiFiScanResult::get_rssi() const { return this->rssi_; }
 bool WiFiScanResult::get_with_auth() const { return this->with_auth_; }
@@ -2284,7 +2352,7 @@ void WiFiComponent::process_roaming_scan_() {
 
   for (const auto &result : this->scan_result_) {
     // Must be same SSID, different BSSID
-    if (current_ssid != result.get_ssid() || result.get_bssid() == current_bssid)
+    if (result.ssid_ != current_ssid || result.get_bssid() == current_bssid)
       continue;
 
 #if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE

esphome/components/wifi/wifi_component.h

@@ -172,12 +172,67 @@ template<typename T> using wifi_scan_vector_t = std::vector<T>;
 template<typename T> using wifi_scan_vector_t = FixedVector<T>;
 #endif
 
+/// 20-byte string: 18 chars inline + null, heap for longer. Always null-terminated.
+/// Used internally for WiFi SSID/password storage to reduce heap fragmentation.
+class CompactString {
+ public:
+  static constexpr uint8_t MAX_LENGTH = 127;
+  static constexpr uint8_t INLINE_CAPACITY = 18;  // 18 chars + null terminator fits in 19 bytes
+
+  CompactString() : length_(0), is_heap_(0) { this->storage_[0] = '\0'; }
+  CompactString(const char *str, size_t len);
+  CompactString(const CompactString &other);
+  CompactString(CompactString &&other) noexcept;
+  CompactString &operator=(const CompactString &other);
+  CompactString &operator=(CompactString &&other) noexcept;
+  ~CompactString();
+
+  const char *data() const { return this->is_heap_ ? this->get_heap_ptr_() : this->storage_; }
+  const char *c_str() const { return this->data(); }  // Always null-terminated
+  size_t size() const { return this->length_; }
+  bool empty() const { return this->length_ == 0; }
+
+  /// Return a StringRef view of this string (zero-copy)
+  StringRef ref() const { return StringRef(this->data(), this->size()); }
+
+  bool operator==(const CompactString &other) const;
+  bool operator!=(const CompactString &other) const { return !(*this == other); }
+  bool operator==(const StringRef &other) const;
+  bool operator!=(const StringRef &other) const { return !(*this == other); }
+  bool operator==(const char *other) const { return *this == StringRef(other); }
+  bool operator!=(const char *other) const { return !(*this == other); }
+
+ protected:
+  char *get_heap_ptr_() const {
+    char *ptr;
+    std::memcpy(&ptr, this->storage_, sizeof(ptr));
+    return ptr;
+  }
+  void set_heap_ptr_(char *ptr) { std::memcpy(this->storage_, &ptr, sizeof(ptr)); }
+
+  // Storage for string data. When is_heap_=0, contains the string directly (null-terminated).
+  // When is_heap_=1, first sizeof(char*) bytes contain pointer to heap allocation.
+  char storage_[INLINE_CAPACITY + 1];  // 19 bytes: 18 chars + null terminator
+  uint8_t length_ : 7;                 // String length (0-127)
+  uint8_t is_heap_ : 1;                // 1 if using heap pointer, 0 if using inline storage
+  // Total size: 20 bytes (19 bytes storage + 1 byte bitfields)
+};
+
+static_assert(sizeof(CompactString) == 20, "CompactString must be exactly 20 bytes");
+
 class WiFiAP {
+  friend class WiFiComponent;
+  friend class WiFiScanResult;
+
  public:
   void set_ssid(const std::string &ssid);
+  void set_ssid(const char *ssid);
+  void set_ssid(StringRef ssid) { this->ssid_ = CompactString(ssid.c_str(), ssid.size()); }
   void set_bssid(const bssid_t &bssid);
   void clear_bssid();
   void set_password(const std::string &password);
+  void set_password(const char *password);
+  void set_password(StringRef password) { this->password_ = CompactString(password.c_str(), password.size()); }
 #ifdef USE_WIFI_WPA2_EAP
   void set_eap(optional<EAPAuth> eap_auth);
 #endif  // USE_WIFI_WPA2_EAP
@@ -188,10 +243,10 @@ class WiFiAP {
   void set_manual_ip(optional<ManualIP> manual_ip);
 #endif
   void set_hidden(bool hidden);
-  const std::string &get_ssid() const;
+  StringRef get_ssid() const { return this->ssid_.ref(); }
+  StringRef get_password() const { return this->password_.ref(); }
   const bssid_t &get_bssid() const;
   bool has_bssid() const;
-  const std::string &get_password() const;
 #ifdef USE_WIFI_WPA2_EAP
   const optional<EAPAuth> &get_eap() const;
 #endif  // USE_WIFI_WPA2_EAP
@@ -204,8 +259,8 @@ class WiFiAP {
   bool get_hidden() const;
 
  protected:
-  std::string ssid_;
-  std::string password_;
+  CompactString ssid_;
+  CompactString password_;
 #ifdef USE_WIFI_WPA2_EAP
   optional<EAPAuth> eap_;
 #endif  // USE_WIFI_WPA2_EAP
@@ -220,15 +275,18 @@ class WiFiAP {
 };
 
 class WiFiScanResult {
+  friend class WiFiComponent;
+
  public:
-  WiFiScanResult(const bssid_t &bssid, std::string ssid, uint8_t channel, int8_t rssi, bool with_auth, bool is_hidden);
+  WiFiScanResult(const bssid_t &bssid, const char *ssid, size_t ssid_len, uint8_t channel, int8_t rssi, bool with_auth,
+                 bool is_hidden);
 
   bool matches(const WiFiAP &config) const;
 
   bool get_matches() const;
   void set_matches(bool matches);
   const bssid_t &get_bssid() const;
-  const std::string &get_ssid() const;
+  StringRef get_ssid() const { return this->ssid_.ref(); }
   uint8_t get_channel() const;
   int8_t get_rssi() const;
   bool get_with_auth() const;
@@ -242,7 +300,7 @@ class WiFiScanResult {
   bssid_t bssid_;
   uint8_t channel_;
   int8_t rssi_;
-  std::string ssid_;
+  CompactString ssid_;
   int8_t priority_{0};
   bool matches_{false};
   bool with_auth_;
@@ -381,6 +439,8 @@ class WiFiComponent : public Component {
   void set_passive_scan(bool passive);
 
   void save_wifi_sta(const std::string &ssid, const std::string &password);
+  void save_wifi_sta(const char *ssid, const char *password);
+  void save_wifi_sta(StringRef ssid, StringRef password) { this->save_wifi_sta(ssid.c_str(), password.c_str()); }
 
   // ========== INTERNAL METHODS ==========
   // (In most use cases you won't need these)
@@ -545,7 +605,7 @@ class WiFiComponent : public Component {
   int8_t find_first_non_hidden_index_() const;
   /// Check if an SSID was seen in the most recent scan results
   /// Used to skip hidden mode for SSIDs we know are visible
-  bool ssid_was_seen_in_scan_(const std::string &ssid) const;
+  bool ssid_was_seen_in_scan_(const CompactString &ssid) const;
   /// Check if full scan results are needed (captive portal active, improv, listeners)
   bool needs_full_scan_results_() const;
   /// Check if network matches any configured network (for scan result filtering)

esphome/components/wifi/wifi_component_esp8266.cpp

@@ -247,16 +247,16 @@ bool WiFiComponent::wifi_sta_connect_(const WiFiAP &ap) {
 
   struct station_config conf {};
   memset(&conf, 0, sizeof(conf));
-  if (ap.get_ssid().size() > sizeof(conf.ssid)) {
+  if (ap.ssid_.size() > sizeof(conf.ssid)) {
     ESP_LOGE(TAG, "SSID too long");
     return false;
   }
-  if (ap.get_password().size() > sizeof(conf.password)) {
+  if (ap.password_.size() > sizeof(conf.password)) {
     ESP_LOGE(TAG, "Password too long");
     return false;
   }
-  memcpy(reinterpret_cast<char *>(conf.ssid), ap.get_ssid().c_str(), ap.get_ssid().size());
-  memcpy(reinterpret_cast<char *>(conf.password), ap.get_password().c_str(), ap.get_password().size());
+  memcpy(reinterpret_cast<char *>(conf.ssid), ap.ssid_.c_str(), ap.ssid_.size());
+  memcpy(reinterpret_cast<char *>(conf.password), ap.password_.c_str(), ap.password_.size());
 
   if (ap.has_bssid()) {
     conf.bssid_set = 1;
@@ -266,7 +266,7 @@ bool WiFiComponent::wifi_sta_connect_(const WiFiAP &ap) {
   }
 
 #if USE_ARDUINO_VERSION_CODE >= VERSION_CODE(2, 4, 0)
-  if (ap.get_password().empty()) {
+  if (ap.password_.empty()) {
     conf.threshold.authmode = AUTH_OPEN;
   } else {
     // Set threshold based on configured minimum auth mode
@@ -738,8 +738,8 @@ void WiFiComponent::wifi_scan_done_callback_(void *arg, STATUS status) {
     const char *ssid_cstr = reinterpret_cast<const char *>(it->ssid);
     if (needs_full || this->matches_configured_network_(ssid_cstr, it->bssid)) {
       this->scan_result_.emplace_back(
-          bssid_t{it->bssid[0], it->bssid[1], it->bssid[2], it->bssid[3], it->bssid[4], it->bssid[5]},
-          std::string(ssid_cstr, it->ssid_len), it->channel, it->rssi, it->authmode != AUTH_OPEN, it->is_hidden != 0);
+          bssid_t{it->bssid[0], it->bssid[1], it->bssid[2], it->bssid[3], it->bssid[4], it->bssid[5]}, ssid_cstr,
+          it->ssid_len, it->channel, it->rssi, it->authmode != AUTH_OPEN, it->is_hidden != 0);
     } else {
       this->log_discarded_scan_result_(ssid_cstr, it->bssid, it->rssi, it->channel);
     }
@@ -832,27 +832,27 @@ bool WiFiComponent::wifi_start_ap_(const WiFiAP &ap) {
     return false;
 
   struct softap_config conf {};
-  if (ap.get_ssid().size() > sizeof(conf.ssid)) {
+  if (ap.ssid_.size() > sizeof(conf.ssid)) {
     ESP_LOGE(TAG, "AP SSID too long");
     return false;
   }
-  memcpy(reinterpret_cast<char *>(conf.ssid), ap.get_ssid().c_str(), ap.get_ssid().size());
-  conf.ssid_len = static_cast<uint8>(ap.get_ssid().size());
+  memcpy(reinterpret_cast<char *>(conf.ssid), ap.ssid_.c_str(), ap.ssid_.size());
+  conf.ssid_len = static_cast<uint8>(ap.ssid_.size());
   conf.channel = ap.has_channel() ? ap.get_channel() : 1;
   conf.ssid_hidden = ap.get_hidden();
   conf.max_connection = 5;
   conf.beacon_interval = 100;
 
-  if (ap.get_password().empty()) {
+  if (ap.password_.empty()) {
     conf.authmode = AUTH_OPEN;
     *conf.password = 0;
   } else {
     conf.authmode = AUTH_WPA2_PSK;
-    if (ap.get_password().size() > sizeof(conf.password)) {
+    if (ap.password_.size() > sizeof(conf.password)) {
       ESP_LOGE(TAG, "AP password too long");
       return false;
     }
-    memcpy(reinterpret_cast<char *>(conf.password), ap.get_password().c_str(), ap.get_password().size());
+    memcpy(reinterpret_cast<char *>(conf.password), ap.password_.c_str(), ap.password_.size());
   }
 
   ETS_UART_INTR_DISABLE();

esphome/components/wifi/wifi_component_esp_idf.cpp

@@ -300,19 +300,19 @@ bool WiFiComponent::wifi_sta_connect_(const WiFiAP &ap) {
   // https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/network/esp_wifi.html#_CPPv417wifi_sta_config_t
   wifi_config_t conf;
   memset(&conf, 0, sizeof(conf));
-  if (ap.get_ssid().size() > sizeof(conf.sta.ssid)) {
+  if (ap.ssid_.size() > sizeof(conf.sta.ssid)) {
     ESP_LOGE(TAG, "SSID too long");
     return false;
   }
-  if (ap.get_password().size() > sizeof(conf.sta.password)) {
+  if (ap.password_.size() > sizeof(conf.sta.password)) {
     ESP_LOGE(TAG, "Password too long");
     return false;
   }
-  memcpy(reinterpret_cast<char *>(conf.sta.ssid), ap.get_ssid().c_str(), ap.get_ssid().size());
-  memcpy(reinterpret_cast<char *>(conf.sta.password), ap.get_password().c_str(), ap.get_password().size());
+  memcpy(reinterpret_cast<char *>(conf.sta.ssid), ap.ssid_.c_str(), ap.ssid_.size());
+  memcpy(reinterpret_cast<char *>(conf.sta.password), ap.password_.c_str(), ap.password_.size());
 
   // The weakest authmode to accept in the fast scan mode
-  if (ap.get_password().empty()) {
+  if (ap.password_.empty()) {
     conf.sta.threshold.authmode = WIFI_AUTH_OPEN;
   } else {
     // Set threshold based on configured minimum auth mode
@@ -864,8 +864,7 @@ void WiFiComponent::wifi_process_event_(IDFWiFiEvent *data) {
       if (needs_full || this->matches_configured_network_(ssid_cstr, record.bssid)) {
         bssid_t bssid;
         std::copy(record.bssid, record.bssid + 6, bssid.begin());
-        std::string ssid(ssid_cstr);
-        this->scan_result_.emplace_back(bssid, std::move(ssid), record.primary, record.rssi,
+        this->scan_result_.emplace_back(bssid, ssid_cstr, strlen(ssid_cstr), record.primary, record.rssi,
                                         record.authmode != WIFI_AUTH_OPEN, ssid_cstr[0] == '\0');
       } else {
         this->log_discarded_scan_result_(ssid_cstr, record.bssid, record.rssi, record.primary);
@@ -1055,26 +1054,26 @@ bool WiFiComponent::wifi_start_ap_(const WiFiAP &ap) {
 
   wifi_config_t conf;
   memset(&conf, 0, sizeof(conf));
-  if (ap.get_ssid().size() > sizeof(conf.ap.ssid)) {
+  if (ap.ssid_.size() > sizeof(conf.ap.ssid)) {
     ESP_LOGE(TAG, "AP SSID too long");
     return false;
   }
-  memcpy(reinterpret_cast<char *>(conf.ap.ssid), ap.get_ssid().c_str(), ap.get_ssid().size());
+  memcpy(reinterpret_cast<char *>(conf.ap.ssid), ap.ssid_.c_str(), ap.ssid_.size());
   conf.ap.channel = ap.has_channel() ? ap.get_channel() : 1;
-  conf.ap.ssid_hidden = ap.get_ssid().size();
+  conf.ap.ssid_hidden = ap.get_hidden();
   conf.ap.max_connection = 5;
   conf.ap.beacon_interval = 100;
 
-  if (ap.get_password().empty()) {
+  if (ap.password_.empty()) {
     conf.ap.authmode = WIFI_AUTH_OPEN;
     *conf.ap.password = 0;
   } else {
     conf.ap.authmode = WIFI_AUTH_WPA2_PSK;
-    if (ap.get_password().size() > sizeof(conf.ap.password)) {
+    if (ap.password_.size() > sizeof(conf.ap.password)) {
       ESP_LOGE(TAG, "AP password too long");
       return false;
     }
-    memcpy(reinterpret_cast<char *>(conf.ap.password), ap.get_password().c_str(), ap.get_password().size());
+    memcpy(reinterpret_cast<char *>(conf.ap.password), ap.password_.c_str(), ap.password_.size());
   }
 
   // pairwise cipher of SoftAP, group cipher will be derived using this.

esphome/components/wifi/wifi_component_libretiny.cpp

@@ -193,7 +193,7 @@ bool WiFiComponent::wifi_sta_connect_(const WiFiAP &ap) {
     return false;
 
   String ssid = WiFi.SSID();
-  if (ssid && strcmp(ssid.c_str(), ap.get_ssid().c_str()) != 0) {
+  if (ssid && strcmp(ssid.c_str(), ap.ssid_.c_str()) != 0) {
     WiFi.disconnect();
   }
 
@@ -213,7 +213,7 @@ bool WiFiComponent::wifi_sta_connect_(const WiFiAP &ap) {
   s_sta_state = LTWiFiSTAState::CONNECTING;
   s_ignored_disconnect_count = 0;
 
-  WiFiStatus status = WiFi.begin(ap.get_ssid().c_str(), ap.get_password().empty() ? NULL : ap.get_password().c_str(),
+  WiFiStatus status = WiFi.begin(ap.ssid_.c_str(), ap.password_.empty() ? NULL : ap.password_.c_str(),
                                  ap.get_channel(),  // 0 = auto
                                  ap.has_bssid() ? ap.get_bssid().data() : NULL);
   if (status != WL_CONNECTED) {
@@ -688,7 +688,7 @@ void WiFiComponent::wifi_scan_done_callback_() {
       auto &ap = scan->ap[i];
       this->scan_result_.emplace_back(bssid_t{ap.bssid.addr[0], ap.bssid.addr[1], ap.bssid.addr[2], ap.bssid.addr[3],
                                               ap.bssid.addr[4], ap.bssid.addr[5]},
-                                      std::string(ssid_cstr), ap.channel, ap.rssi, ap.auth != WIFI_AUTH_OPEN,
+                                      ssid_cstr, strlen(ssid_cstr), ap.channel, ap.rssi, ap.auth != WIFI_AUTH_OPEN,
                                       ssid_cstr[0] == '\0');
     } else {
       auto &ap = scan->ap[i];
@@ -735,7 +735,7 @@ bool WiFiComponent::wifi_start_ap_(const WiFiAP &ap) {
 
   yield();
 
-  return WiFi.softAP(ap.get_ssid().c_str(), ap.get_password().empty() ? NULL : ap.get_password().c_str(),
+  return WiFi.softAP(ap.ssid_.c_str(), ap.password_.empty() ? NULL : ap.password_.c_str(),
                      ap.has_channel() ? ap.get_channel() : 1, ap.get_hidden());
 }
 

esphome/components/wifi/wifi_component_pico_w.cpp

@@ -78,7 +78,7 @@ bool WiFiComponent::wifi_sta_connect_(const WiFiAP &ap) {
     return false;
 #endif
 
-  auto ret = WiFi.begin(ap.get_ssid().c_str(), ap.get_password().c_str());
+  auto ret = WiFi.begin(ap.ssid_.c_str(), ap.password_.c_str());
   if (ret != WL_CONNECTED)
     return false;
 
@@ -149,9 +149,8 @@ void WiFiComponent::wifi_scan_result(void *env, const cyw43_ev_scan_result_t *re
 
   bssid_t bssid;
   std::copy(result->bssid, result->bssid + 6, bssid.begin());
-  std::string ssid(ssid_cstr);
-  WiFiScanResult res(bssid, std::move(ssid), result->channel, result->rssi, result->auth_mode != CYW43_AUTH_OPEN,
-                     ssid_cstr[0] == '\0');
+  WiFiScanResult res(bssid, ssid_cstr, strlen(ssid_cstr), result->channel, result->rssi,
+                     result->auth_mode != CYW43_AUTH_OPEN, ssid_cstr[0] == '\0');
   if (std::find(this->scan_result_.begin(), this->scan_result_.end(), res) == this->scan_result_.end()) {
     this->scan_result_.push_back(res);
   }
@@ -204,7 +203,7 @@ bool WiFiComponent::wifi_start_ap_(const WiFiAP &ap) {
   }
 #endif
 
-  WiFi.beginAP(ap.get_ssid().c_str(), ap.get_password().c_str(), ap.has_channel() ? ap.get_channel() : 1);
+  WiFi.beginAP(ap.ssid_.c_str(), ap.password_.c_str(), ap.has_channel() ? ap.get_channel() : 1);
 
   return true;
 }

esphome/components/wifi_info/wifi_info_text_sensor.cpp

@@ -89,7 +89,7 @@ void ScanResultsWiFiInfo::on_wifi_scan_results(const wifi::wifi_scan_vector_t<wi
   for (const auto &scan : results) {
     if (scan.get_is_hidden())
       continue;
-    const std::string &ssid = scan.get_ssid();
+    const auto &ssid = scan.get_ssid();
     // Max space: ssid + ": " (2) + "-128" (4) + "dB\n" (3) = ssid + 9
     if (ptr + ssid.size() + 9 > end)
       break;

esphome/components/zigbee/zigbee_zephyr.cpp

@@ -61,11 +61,19 @@ void ZigbeeComponent::zboss_signal_handler_esphome(zb_bufid_t bufid) {
       break;
   }
 
+  auto before = millis();
   auto err = zigbee_default_signal_handler(bufid);
   if (err != RET_OK) {
     ESP_LOGE(TAG, "Zigbee_default_signal_handler ERROR %u [%s]", err, zb_error_to_string_get(err));
   }
 
+  if (sig == ZB_COMMON_SIGNAL_CAN_SLEEP) {
+    this->sleep_remainder_ += millis() - before;
+    uint32_t seconds = this->sleep_remainder_ / 1000;
+    this->sleep_remainder_ -= seconds * 1000;
+    this->sleep_time_ += seconds;
+  }
+
   switch (sig) {
     case ZB_BDB_SIGNAL_STEERING:
       ESP_LOGD(TAG, "ZB_BDB_SIGNAL_STEERING, status: %d", status);
@@ -213,6 +221,7 @@ void ZigbeeComponent::dump_config() {
                 "Zigbee\n"
                 "  Wipe on boot: %s\n"
                 "  Device is joined to the network: %s\n"
+                "  Sleep time: %us\n"
                 "  Current channel: %d\n"
                 "  Current page: %d\n"
                 "  Sleep threshold: %ums\n"
@@ -221,9 +230,9 @@ void ZigbeeComponent::dump_config() {
                 "  Short addr: 0x%04X\n"
                 "  Long pan id: 0x%s\n"
                 "  Short pan id: 0x%04X",
-                get_wipe_on_boot(), YESNO(zb_zdo_joined()), zb_get_current_channel(), zb_get_current_page(),
-                zb_get_sleep_threshold(), role(), ieee_addr_buf, zb_get_short_address(), extended_pan_id_buf,
-                zb_get_pan_id());
+                get_wipe_on_boot(), YESNO(zb_zdo_joined()), this->sleep_time_, zb_get_current_channel(),
+                zb_get_current_page(), zb_get_sleep_threshold(), role(), ieee_addr_buf, zb_get_short_address(),
+                extended_pan_id_buf, zb_get_pan_id());
   dump_reporting_();
 }
 

esphome/components/zigbee/zigbee_zephyr.h

@@ -92,6 +92,8 @@ class ZigbeeComponent : public Component {
   CallbackManager<void()> join_cb_;
   Trigger<> join_trigger_;
   bool force_report_{false};
+  uint32_t sleep_time_{};
+  uint32_t sleep_remainder_{};
 };
 
 class ZigbeeEntity {

esphome/const.py

@@ -639,6 +639,7 @@ CONF_MOVEMENT_COUNTER = "movement_counter"
 CONF_MOVING_DISTANCE = "moving_distance"
 CONF_MQTT = "mqtt"
 CONF_MQTT_ID = "mqtt_id"
+CONF_MQTT_JSON_STATE_PAYLOAD = "mqtt_json_state_payload"
 CONF_MULTIPLE = "multiple"
 CONF_MULTIPLEXER = "multiplexer"
 CONF_MULTIPLY = "multiply"

esphome/core/application.cpp

@@ -609,15 +609,6 @@ void Application::unregister_socket_fd(int fd) {
   }
 }
 
-bool Application::is_socket_ready(int fd) const {
-  // This function is thread-safe for reading the result of select()
-  // However, it should only be called after select() has been executed in the main loop
-  // The read_fds_ is only modified by select() in the main loop
-  if (fd < 0 || fd >= FD_SETSIZE)
-    return false;
-
-  return FD_ISSET(fd, &this->read_fds_);
-}
 #endif
 
 void Application::yield_with_select_(uint32_t delay_ms) {

esphome/core/application.h

@@ -94,6 +94,9 @@
 #ifdef USE_INFRARED
 #include "esphome/components/infrared/infrared.h"
 #endif
+#ifdef USE_SERIAL_PROXY
+#include "esphome/components/serial_proxy/serial_proxy.h"
+#endif
 #ifdef USE_EVENT
 #include "esphome/components/event/event.h"
 #endif
@@ -101,6 +104,10 @@
 #include "esphome/components/update/update_entity.h"
 #endif
 
+namespace esphome::socket {
+class Socket;
+}  // namespace esphome::socket
+
 namespace esphome {
 
 // Teardown timeout constant (in milliseconds)
@@ -230,6 +237,13 @@ class Application {
   void register_infrared(infrared::Infrared *infrared) { this->infrareds_.push_back(infrared); }
 #endif
 
+#ifdef USE_SERIAL_PROXY
+  void register_serial_proxy(serial_proxy::SerialProxy *proxy) {
+    proxy->set_instance_index(this->serial_proxies_.size());
+    this->serial_proxies_.push_back(proxy);
+  }
+#endif
+
 #ifdef USE_EVENT
   void register_event(event::Event *event) { this->events_.push_back(event); }
 #endif
@@ -469,6 +483,10 @@ class Application {
   GET_ENTITY_METHOD(infrared::Infrared, infrared, infrareds)
 #endif
 
+#ifdef USE_SERIAL_PROXY
+  auto &get_serial_proxies() const { return this->serial_proxies_; }
+#endif
+
 #ifdef USE_EVENT
   auto &get_events() const { return this->events_; }
   GET_ENTITY_METHOD(event::Event, event, events)
@@ -491,7 +509,8 @@ class Application {
   void unregister_socket_fd(int fd);
   /// Check if there's data available on a socket without blocking
   /// This function is thread-safe for reading, but should be called after select() has run
-  bool is_socket_ready(int fd) const;
+  /// The read_fds_ is only modified by select() in the main loop
+  bool is_socket_ready(int fd) const { return fd >= 0 && this->is_socket_ready_(fd); }
 
 #ifdef USE_WAKE_LOOP_THREADSAFE
   /// Wake the main event loop from a FreeRTOS task
@@ -503,6 +522,15 @@ class Application {
 
  protected:
   friend Component;
+  friend class socket::Socket;
+
+#ifdef USE_SOCKET_SELECT_SUPPORT
+  /// Fast path for Socket::ready() via friendship - skips negative fd check.
+  /// Safe because: fd was validated in register_socket_fd() at registration time,
+  /// and Socket::ready() only calls this when loop_monitored_ is true (registration succeeded).
+  /// FD_ISSET may include its own upper bounds check depending on platform.
+  bool is_socket_ready_(int fd) const { return FD_ISSET(fd, &this->read_fds_); }
+#endif
 
   void register_component_(Component *comp);
 
@@ -676,6 +704,9 @@ class Application {
 #ifdef USE_INFRARED
   StaticVector<infrared::Infrared *, ESPHOME_ENTITY_INFRARED_COUNT> infrareds_{};
 #endif
+#ifdef USE_SERIAL_PROXY
+  std::vector<serial_proxy::SerialProxy *> serial_proxies_{};
+#endif
 #ifdef USE_UPDATE
   StaticVector<update::UpdateEntity *, ESPHOME_ENTITY_UPDATE_COUNT> updates_{};
 #endif

esphome/core/defines.h

@@ -14,6 +14,7 @@
 #define ESPHOME_PROJECT_VERSION_30 "v2"
 #define ESPHOME_VARIANT "ESP32"
 #define ESPHOME_DEBUG_SCHEDULER
+#define ESPHOME_DEBUG_API
 
 // Default threading model for static analysis (ESP32 is multi-threaded with atomics)
 #define ESPHOME_THREAD_MULTI_ATOMICS
@@ -108,6 +109,7 @@
 #define USE_SAFE_MODE_CALLBACK
 #define USE_SELECT
 #define USE_SENSOR
+#define USE_SERIAL_PROXY
 #define USE_STATUS_LED
 #define USE_STATUS_SENSOR
 #define USE_SWITCH
@@ -145,6 +147,7 @@
 #define USE_MD5
 #define USE_SHA256
 #define USE_MQTT
+#define USE_MQTT_COVER_JSON
 #define USE_NETWORK
 #define USE_ONLINE_IMAGE_BMP_SUPPORT
 #define USE_ONLINE_IMAGE_PNG_SUPPORT
@@ -320,6 +323,7 @@
 #endif
 
 #ifdef USE_NRF52
+#define USE_ESPHOME_TASK_LOG_BUFFER
 #define USE_NRF52_DFU
 #define USE_NRF52_REG0_VOUT 5
 #define USE_NRF52_UICR_ERASE

tests/components/logger/test.nrf52-adafruit.yaml

@@ -5,3 +5,4 @@ esphome:
 
 logger:
   level: DEBUG
+  task_log_buffer_size: 0

tests/components/mqtt/common.yaml

@@ -219,6 +219,7 @@ cover:
     name: Template Cover
     state_topic: some/topic/cover
     qos: 2
+    mqtt_json_state_payload: true
     lambda: |-
       if (id(some_binary_sensor).state) {
         return COVER_OPEN;
@@ -231,6 +232,53 @@ cover:
     stop_action:
       - logger.log: stop_action
     optimistic: true
+  - platform: template
+    name: Template Cover with Position and Tilt
+    state_topic: some/topic/cover_pt
+    position_state_topic: some/topic/cover_pt/position
+    position_command_topic: some/topic/cover_pt/position/set
+    tilt_state_topic: some/topic/cover_pt/tilt
+    tilt_command_topic: some/topic/cover_pt/tilt/set
+    qos: 2
+    has_position: true
+    lambda: |-
+      if (id(some_binary_sensor).state) {
+        return COVER_OPEN;
+      }
+      return COVER_CLOSED;
+    position_action:
+      - logger.log: position_action
+    tilt_action:
+      - logger.log: tilt_action
+    open_action:
+      - logger.log: open_action
+    close_action:
+      - logger.log: close_action
+    stop_action:
+      - logger.log: stop_action
+    optimistic: true
+  - platform: template
+    name: Template Cover with Position and Tilt JSON
+    state_topic: some/topic/cover_pt_json
+    qos: 2
+    mqtt_json_state_payload: true
+    has_position: true
+    lambda: |-
+      if (id(some_binary_sensor).state) {
+        return COVER_OPEN;
+      }
+      return COVER_CLOSED;
+    position_action:
+      - logger.log: position_action
+    tilt_action:
+      - logger.log: tilt_action
+    open_action:
+      - logger.log: open_action
+    close_action:
+      - logger.log: close_action
+    stop_action:
+      - logger.log: stop_action
+    optimistic: true
 
 datetime:
   - platform: template

tests/components/serial_proxy/common.yaml

@@ -0,0 +1,8 @@
+wifi:
+  ssid: MySSID
+  password: password1
+
+api:
+
+serial_proxy:
+  - id: serial_proxy_1

tests/components/serial_proxy/test.esp32-idf.yaml

@@ -0,0 +1,8 @@
+substitutions:
+  tx_pin: GPIO4
+  rx_pin: GPIO5
+
+packages:
+  uart: !include ../../test_build_components/common/uart/esp32-idf.yaml
+
+<<: !include common.yaml

tests/components/serial_proxy/test.esp8266-ard.yaml

@@ -0,0 +1,8 @@
+substitutions:
+  tx_pin: GPIO0
+  rx_pin: GPIO2
+
+packages:
+  uart: !include ../../test_build_components/common/uart/esp8266-ard.yaml
+
+<<: !include common.yaml

tests/components/serial_proxy/test.rp2040-ard.yaml

@@ -0,0 +1,8 @@
+substitutions:
+  tx_pin: GPIO4
+  rx_pin: GPIO5
+
+packages:
+  uart: !include ../../test_build_components/common/uart/rp2040-ard.yaml
+
+<<: !include common.yaml

tests/integration/conftest.py

@@ -197,6 +197,7 @@ async def yaml_config(request: pytest.FixtureRequest, unused_tcp_port: int) -> s
             "  platformio_options:\n"
             "    build_flags:\n"
             '      - "-DDEBUG"  # Enable assert() statements\n'
+            '      - "-DESPHOME_DEBUG_API"  # Enable API protocol asserts\n'
             '      - "-g"       # Add debug symbols',
         )