Merge remote-tracking branch 'origin/logger-simplify' into HEAD

# Conflicts:
#	tests/component_tests/logger/test_logger.py

esphome/components/logger/__init__.py

@@ -37,6 +37,7 @@ from esphome.types import ConfigType
 _LOGGER = logging.getLogger(__name__)
 
 CODEOWNERS = ["@esphome/core"]
+DOMAIN = "logger"
 logger_ns = cg.esphome_ns.namespace("logger")
 LOG_LEVELS = {
     "NONE": cg.global_ns.ESPHOME_LOG_LEVEL_NONE,
@@ -93,6 +94,7 @@ UART_SELECTION_RP2040 = [USB_CDC, UART0, UART1]
 
 UART_SELECTION_NRF52 = [USB_CDC, UART0]
 
+# Read by device-builder
 HARDWARE_UART_TO_UART_SELECTION = {
     UART0: logger_ns.UART_SELECTION_UART0,
     UART0_SWAP: logger_ns.UART_SELECTION_UART0_SWAP,
@@ -108,8 +110,6 @@ HARDWARE_UART_TO_SERIAL = {
         UART0: cg.global_ns.Serial,
         UART0_SWAP: cg.global_ns.Serial,
         UART1: cg.global_ns.Serial1,
-        UART2: cg.global_ns.Serial2,
-        DEFAULT: cg.global_ns.Serial,
     },
     PLATFORM_RP2: {
         UART0: cg.global_ns.Serial1,
@@ -503,13 +503,10 @@ async def to_code(config: ConfigType) -> None:
     CORE.data.setdefault(DOMAIN, {})[CONF_LEVEL] = level
     tx_buffer_size = config[CONF_TX_BUFFER_SIZE]
     cg.add_define("ESPHOME_LOGGER_TX_BUFFER_SIZE", tx_buffer_size)
-    # Determine task log buffer size. The buffer is a direct member of Logger
-    # (no separate heap allocation).
-    task_log_buffer_size = 0
-    if CORE.is_esp32 or CORE.is_libretiny or CORE.is_nrf52:
-        task_log_buffer_size = config[CONF_TASK_LOG_BUFFER_SIZE]
-    elif CORE.is_host:
-        task_log_buffer_size = 64  # Fixed 64 slots for host
+    # The host has a fixed 64 slots
+    task_log_buffer_size = (
+        64 if CORE.is_host else config.get(CONF_TASK_LOG_BUFFER_SIZE, 0)
+    )
     if task_log_buffer_size > 0:
         cg.add_define("USE_ESPHOME_TASK_LOG_BUFFER")
         cg.add_define("ESPHOME_TASK_LOG_BUFFER_SIZE", task_log_buffer_size)
@@ -542,17 +539,17 @@ async def to_code(config: ConfigType) -> None:
                 cg.add(log.set_boot_log_level(tag, LOG_LEVELS[log_level]))
     if CORE.is_esp32 or CORE.is_host:
         cg.add(log.create_pthread_key())
-    # set_uart_selection() must be called before pre_setup() because
-    # pre_setup() switches on uart_ to decide which hardware to initialize
-    # (e.g. UART0 vs USB_SERIAL_JTAG). Without this, uart_ is still the
-    # default UART_SELECTION_UART0 and the wrong hardware gets initialized.
-    # uart_ is UART0 in C++ except on LibreTiny where it is DEFAULT; skip the
-    # setter when the config matches it.
-    cpp_default_uart = DEFAULT if CORE.is_libretiny else UART0
-    if (
-        hardware_uart := config.get(CONF_HARDWARE_UART)
-    ) is not None and hardware_uart != cpp_default_uart:
-        cg.add(log.set_uart_selection(HARDWARE_UART_TO_UART_SELECTION[hardware_uart]))
+    if (hardware_uart := config.get(CONF_HARDWARE_UART)) is not None:
+        cg.add_define(f"USE_LOGGER_UART_SELECTION_{hardware_uart}")
+        cg.add_define(
+            "ESPHOME_LOGGER_UART_SELECTION",
+            cg.RawExpression(f"logger::UART_SELECTION_{hardware_uart}"),
+        )
+        # ESP8266 without serial logging never opens a port
+        cg.add_define(
+            "ESPHOME_LOGGER_UART_NAME",
+            "NONE" if CORE.is_esp8266 and baud_rate == 0 else hardware_uart,
+        )
     # pre_setup() sets global_logger and must run before any other code
     # that may call ESP_LOG* (e.g. setup_preferences contains ESP_LOGVV).
     cg.add(log.pre_setup())
@@ -647,10 +644,8 @@ async def _late_logger_init(config: ConfigType) -> None:
 
         if config[CONF_HARDWARE_UART] == USB_CDC:
             add_idf_sdkconfig_option("CONFIG_ESP_CONSOLE_USB_CDC", True)
-            cg.add_define("USE_LOGGER_UART_SELECTION_USB_CDC")
         elif config[CONF_HARDWARE_UART] == USB_SERIAL_JTAG:
             add_idf_sdkconfig_option("CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG", True)
-            cg.add_define("USE_LOGGER_UART_SELECTION_USB_SERIAL_JTAG")
         # Log V2 formats centrally in esp_log() (~4KB flash, ~180B RAM). 6.1
         # adds CONSTRAINED_ENV_SAFE=n, keeping early/DRAM logs on
         # esp_rom_printf instead of pulling ~1.2KB esp_rom_vprintf into IRAM.
@@ -667,8 +662,13 @@ async def _late_logger_init(config: ConfigType) -> None:
             cg.add_define("USE_ESP32_LOG_V2")
             # --wrap: a strong definition collides; see logger_esp32.cpp
             cg.add_build_flag("-Wl,--wrap=esp_log_format")
-    if CORE.is_rp2 and config[CONF_HARDWARE_UART] == USB_CDC:
-        cg.add_define("USE_LOGGER_UART_SELECTION_USB_CDC")
+    # Zephyr polls the USB port only when it logs there
+    if (
+        CORE.using_zephyr
+        and has_serial_logging
+        and config[CONF_HARDWARE_UART] == USB_CDC
+    ):
+        cg.add_define("USE_LOGGER_ZEPHYR_CDC_LOOP")
     # Define platform support flags for components that need auto-detection
     try:
         uart_selection(USB_SERIAL_JTAG)
@@ -718,7 +718,6 @@ async def _late_logger_init(config: ConfigType) -> None:
             if config[CONF_HARDWARE_UART] == UART1:
                 zephyr_add_overlay("""&uart1 { status = "okay";};""")
             if config[CONF_HARDWARE_UART] == USB_CDC:
-                cg.add_define("USE_LOGGER_UART_SELECTION_USB_CDC")
                 zephyr_add_prj_conf("UART_LINE_CTRL", True)
 
     # Register at end for safe mode
@@ -739,8 +738,6 @@ async def _late_logger_init(config: ConfigType) -> None:
             conf,
         )
 
-    CORE.add_job(final_step)
-
 
 def validate_printf(value: ConfigType) -> ConfigType:
     # https://stackoverflow.com/questions/30011379/how-can-i-parse-a-c-format-string-in-python
@@ -875,11 +872,6 @@ FILTER_SOURCE_FILES = filter_source_files_from_platform(
     }
 )
 
-# Keys for CORE.data storage
-DOMAIN = "logger"
-KEY_LEVEL_LISTENERS = "level_listeners"
-KEY_LOG_LISTENERS = "log_listeners"
-
 
 def request_logger_level_listeners() -> None:
     """Request that logger level listeners be compiled in.
@@ -888,29 +880,18 @@ def request_logger_level_listeners() -> None:
     function during their code generation. This enables the add_level_listener()
     method and compiles in the listener vector.
     """
-    CORE.data.setdefault(DOMAIN, {})[KEY_LEVEL_LISTENERS] = True
+    cg.add_define("USE_LOGGER_LEVEL_LISTENERS")
+
+
+_request_log_listener_slot = cg.slot_counter("ESPHOME_LOG_MAX_LISTENERS")
+
+
+def request_console() -> None:
+    """Compile in Logger::console_read() and console_write(); call from to_code."""
+    cg.add_define("USE_LOGGER_CONSOLE")
 
 
 def request_log_listener() -> None:
-    """Request a log listener slot.
-
-    Components that need to receive log messages should call this function
-    during their code generation. This increments the listener count used
-    to size the StaticVector.
-    """
-    data = CORE.data.setdefault(DOMAIN, {})
-    data[KEY_LOG_LISTENERS] = data.get(KEY_LOG_LISTENERS, 0) + 1
-
-
-@coroutine_with_priority(CoroPriority.FINAL)
-async def final_step() -> None:
-    """Final code generation step to configure optional logger features."""
-    domain_data = CORE.data.get(DOMAIN, {})
-    if domain_data.get(KEY_LEVEL_LISTENERS, False):
-        cg.add_define("USE_LOGGER_LEVEL_LISTENERS")
-
-    # Only generate log listener code if any component needs it
-    log_listener_count = domain_data.get(KEY_LOG_LISTENERS, 0)
-    if log_listener_count > 0:
-        cg.add_define("USE_LOG_LISTENERS")
-        cg.add_define("ESPHOME_LOG_MAX_LISTENERS", log_listener_count)
+    """Reserve a log listener slot; call once per listener from to_code."""
+    cg.add_define("USE_LOG_LISTENERS")
+    _request_log_listener_slot()

esphome/components/logger/logger.cpp

@@ -32,7 +32,7 @@ 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)
+#elif defined(USE_ZEPHYR)
   k_tid_t current_task = k_current_get();
   const bool is_main_task = (current_task == this->main_task_);
 #else  // USE_HOST
@@ -57,10 +57,10 @@ void HOT Logger::log_vprintf_(uint8_t level, const char *tag, int line, const ch
   // (we already have the handle from the main task check above).
   // 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);
+  const char *thread_name = this->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);
+  const char *thread_name = this->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);
@@ -103,10 +103,10 @@ void Logger::log_vprintf_non_main_thread_(uint8_t level, const char *tag, int li
   {
 #ifdef USE_HOST
     // Host always has console output - no baud_rate check needed
-    static const size_t MAX_CONSOLE_LOG_MSG_SIZE = 512;
+    static constexpr size_t MAX_CONSOLE_LOG_MSG_SIZE = 512;
 #else
     // Maximum size for console log messages (includes null terminator)
-    static const size_t MAX_CONSOLE_LOG_MSG_SIZE = 144;
+    static constexpr size_t MAX_CONSOLE_LOG_MSG_SIZE = 144;
 #endif
     char console_buffer[MAX_CONSOLE_LOG_MSG_SIZE];  // MUST be stack allocated for thread safety
     LogBuffer buf{console_buffer, MAX_CONSOLE_LOG_MSG_SIZE};
@@ -118,13 +118,11 @@ void Logger::log_vprintf_non_main_thread_(uint8_t level, const char *tag, int li
 }
 #else
 // 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).
+// Logging calls are NOT thread-safe: the recursion guard is a plain bool and tx_buffer_ has no locking.
 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_)
+  if (level > this->level_for(tag) || this->main_task_recursion_guard_)
     return;
-  // 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);
+  this->log_message_to_buffer_and_send_(this->main_task_recursion_guard_, level, tag, line, format, args, nullptr);
 }
 #endif  // USE_ESP32 || USE_HOST || USE_LIBRETINY || USE_ZEPHYR
 
@@ -136,10 +134,10 @@ void HOT Logger::log_vprintf_(uint8_t level, const char *tag, int line, const ch
 //
 void Logger::log_vprintf_(uint8_t level, const char *tag, int line, const __FlashStringHelper *format,
                           va_list args) {  // NOLINT
-  if (level > this->level_for(tag) || global_recursion_guard_)
+  if (level > this->level_for(tag) || this->main_task_recursion_guard_)
     return;
 
-  this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args, nullptr);
+  this->log_message_to_buffer_and_send_(this->main_task_recursion_guard_, level, tag, line, format, args, nullptr);
 }
 #endif  // USE_ESP8266
 
@@ -184,10 +182,10 @@ Logger::Logger(uint32_t baud_rate) : baud_rate_(baud_rate) {
 #endif
 }
 
-#if defined(USE_ESPHOME_TASK_LOG_BUFFER) || (defined(USE_ZEPHYR) && defined(USE_LOGGER_UART_SELECTION_USB_CDC))
+#if defined(USE_ESPHOME_TASK_LOG_BUFFER) || defined(USE_LOGGER_ZEPHYR_CDC_LOOP)
 void Logger::loop() {
   this->process_messages_();
-#if defined(USE_ZEPHYR) && defined(USE_LOGGER_UART_SELECTION_USB_CDC)
+#ifdef USE_LOGGER_ZEPHYR_CDC_LOOP
   this->cdc_loop_();
 #endif
 }
@@ -213,11 +211,11 @@ void Logger::process_messages_() {
       this->write_log_buffer_to_console_(buf);
     }
   }
-#if !(defined(USE_ZEPHYR) && defined(USE_LOGGER_UART_SELECTION_USB_CDC))
+  // Zephyr with USB CDC keeps the loop running for cdc_loop_()
+#ifndef USE_LOGGER_ZEPHYR_CDC_LOOP
   else {
-    // No messages to process, disable loop if appropriate
-    // This reduces overhead when there's no async logging activity
-    this->disable_loop_when_buffer_empty_();
+    // A concurrent enable_loop_soon_any_context() still wakes the next iteration
+    this->disable_loop();
   }
 #endif
 #endif  // USE_ESPHOME_TASK_LOG_BUFFER
@@ -265,7 +263,7 @@ void Logger::boot_log_capture_(uint8_t level, const char *tag, const LogBuffer &
 
 void Logger::replay_boot_logs() {
   // The replay shares tx_buffer_ with normal logging, so it is dropped like any other re-entrant log
-  bool &recursion_guard = this->main_loop_recursion_guard_();
+  bool &recursion_guard = this->main_task_recursion_guard_;
   if (recursion_guard)
     return;
   this->boot_log_done_ = true;  // Stops capture first, so the replay output is not buffered again
@@ -307,6 +305,25 @@ static const LogString *get_log_level_str(uint8_t level) {
   return LogLevelStrings::get_log_str(level, LogLevelStrings::LAST_INDEX);
 }
 
+#ifndef USE_HOST
+const LogString *Logger::get_uart_selection_() {
+#ifdef USE_LOGGER_UART_SELECTION_DEFAULT
+  // LibreTiny resolves DEFAULT to the board's port only when serial logging is on
+  if (this->baud_rate_ > 0) {
+    switch (this->get_uart()) {
+      case UART_SELECTION_UART0:
+        return LOG_STR("UART0");
+      case UART_SELECTION_UART1:
+        return LOG_STR("UART1");
+      default:
+        return LOG_STR("UART2");
+    }
+  }
+#endif
+  return LOG_STR(ESPHOME_LOGGER_UART_NAME);
+}
+#endif
+
 void Logger::dump_config() {
   ESP_LOGCONFIG(TAG,
                 "Logger:\n"
@@ -342,7 +359,7 @@ void Logger::dump_config() {
   }
 #endif
 #ifdef USE_ZEPHYR
-  dump_crash_();
+  this->dump_crash_();
 #ifdef USE_BOOTLOADER_ADAFRUIT
   this->dump_bootloader_();
 #endif

esphome/components/logger/logger.h

@@ -42,9 +42,6 @@ struct device;
 namespace esphome::logger {
 
 /** Lightweight callback for receiving log messages without virtual dispatch overhead.
- *
- * Replaces the former LogListener virtual interface to eliminate per-implementer
- * vtable sub-tables and thunk code (~39 bytes saved per class that used LogListener).
  *
  * Usage:
  *   // In your component's setup():
@@ -73,7 +70,7 @@ struct LogCallback {
  *    public:
  *     void setup() override {
  *       if (logger::global_logger != nullptr)
- *         logger::global_logger->add_logger_level_listener(this);
+ *         logger::global_logger->add_level_listener(this);
  *     }
  *     void on_log_level_change(uint8_t level) override {
  *       // Handle log level change
@@ -127,6 +124,9 @@ enum UARTSelection : uint8_t {
   UART_SELECTION_UART0_SWAP,
 #endif  // USE_ESP8266
 };
+
+// The port chosen by hardware_uart, fixed at build time
+static constexpr UARTSelection CONFIGURED_UART_SELECTION = ESPHOME_LOGGER_UART_SELECTION;
 #endif  // USE_ESP32 || USE_ESP8266 || USE_RP2 || USE_LIBRETINY || USE_ZEPHYR
 
 /**
@@ -138,7 +138,7 @@ enum UARTSelection : uint8_t {
  * - On ESP32: Uses task-specific recursion guards
  *   * Main task: Uses a dedicated boolean member variable for efficiency
  *   * Other tasks: Uses pthread TLS with a dynamically allocated key for task-specific state
- * - On other platforms: Uses a simple global recursion guard
+ * - On single-task platforms: Uses the main task guard alone
  *
  * We use pthread TLS via pthread_key_create to create a unique key for storing
  * task-specific recursion state, which:
@@ -149,7 +149,7 @@ enum UARTSelection : uint8_t {
 class Logger final : public Component {
  public:
   explicit Logger(uint32_t baud_rate);
-#if defined(USE_ESPHOME_TASK_LOG_BUFFER) || (defined(USE_ZEPHYR) && defined(USE_LOGGER_UART_SELECTION_USB_CDC))
+#if defined(USE_ESPHOME_TASK_LOG_BUFFER) || defined(USE_LOGGER_ZEPHYR_CDC_LOOP)
   void loop() override;
 #endif
 #if defined(USE_RP2_CRASH_HANDLER) && defined(USE_LOGGER_UART_SELECTION_USB_CDC)
@@ -157,21 +157,52 @@ class Logger final : public Component {
 #endif
   /// Manually set the baud rate for serial, set to 0 to disable.
   void set_baud_rate(uint32_t baud_rate) { this->baud_rate_ = baud_rate; }
-  uint32_t get_baud_rate() const { return baud_rate_; }
+  uint32_t get_baud_rate() const { return this->baud_rate_; }
 #if defined(USE_ARDUINO) && !defined(USE_ESP32)
-  Stream *get_hw_serial() const { return hw_serial_; }
+  Stream *get_hw_serial() const { return this->hw_serial_; }
 #endif
 #ifdef USE_ESP32
-  uart_port_t get_uart_num() const { return uart_num_; }
-  void create_pthread_key() { pthread_key_create(&log_recursion_key_, nullptr); }
+  /// UART_NUM_0 when logging to USB
+  constexpr uart_port_t get_uart_num() const {
+#if defined(USE_LOGGER_UART_SELECTION_USB_CDC) || defined(USE_LOGGER_UART_SELECTION_USB_SERIAL_JTAG)
+    return UART_NUM_0;
+#else
+    return static_cast<uart_port_t>(CONFIGURED_UART_SELECTION);
 #endif
-#ifdef USE_HOST
-  void create_pthread_key() { pthread_key_create(&log_recursion_key_, nullptr); }
+  }
+#endif
+#if defined(USE_ESP32) || defined(USE_HOST)
+  void create_pthread_key() { pthread_key_create(&this->log_recursion_key_, nullptr); }
 #endif
 #if defined(USE_ESP32) || defined(USE_ESP8266) || defined(USE_RP2) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR)
-  void set_uart_selection(UARTSelection uart_selection) { uart_ = uart_selection; }
   /// Get the UART used by the logger.
-  UARTSelection get_uart() const { return this->uart_; }
+#ifdef USE_LIBRETINY
+  // DEFAULT resolves to the board's default port
+  constexpr UARTSelection get_uart() const {
+    return CONFIGURED_UART_SELECTION == UART_SELECTION_DEFAULT ? static_cast<UARTSelection>(LT_UART_DEFAULT_SERIAL + 1)
+                                                               : CONFIGURED_UART_SELECTION;
+  }
+#else
+  constexpr UARTSelection get_uart() const { return CONFIGURED_UART_SELECTION; }
+#endif
+#endif
+#ifdef USE_LOGGER_CONSOLE
+  // Raw bytes on the console port, without log framing; request with logger.request_console()
+#if defined(USE_ARDUINO) && !defined(USE_ESP32)
+  size_t console_write(const uint8_t *data, size_t len) { return this->hw_serial_->write(data, len); }
+  bool console_read(uint8_t &byte) {
+    int c = this->hw_serial_->read();
+    if (c < 0)
+      return false;
+    byte = c;
+    return true;
+  }
+#elif defined(USE_ESP32)
+  /// Blocking write; returns the bytes written.
+  size_t console_write(const uint8_t *data, size_t len);
+  /// Non-blocking read of one byte; false if none is waiting.
+  bool console_read(uint8_t &byte);
+#endif
 #endif
 
   /// Set the default log level for this logger.
@@ -242,14 +273,17 @@ class Logger final : public Component {
   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_UART_SELECTION_USB_CDC)
+#ifdef USE_LOGGER_ZEPHYR_CDC_LOOP
   void cdc_loop_();
 #endif
   void process_messages_();
-#if defined(USE_HOST) || defined(USE_ZEPHYR)
-  void write_msg_(const char *msg, uint16_t len);
+  // msg already ends in a newline
+#if defined(USE_ARDUINO) && !defined(USE_ESP32)
+  inline void HOT write_msg_(const char *msg, uint16_t len) { this->hw_serial_->write(msg, len); }
+#elif defined(USE_ESP32)
+  inline void write_msg_(const char *msg, uint16_t len);  // Defined in logger_esp32.h
 #else
-  inline void write_msg_(const char *msg, uint16_t len);  // Defined in platform-specific logger_*.h
+  void write_msg_(const char *msg, uint16_t len);
 #endif
 
   // Format a log message with printf-style arguments and write it to a buffer with header, footer, and null terminator
@@ -317,7 +351,6 @@ class Logger final : public Component {
 
 #ifdef USE_ESPHOME_TASK_LOG_BUFFER
   // Helper to format a pre-formatted message from the task log buffer and notify listeners
-  // Used by process_messages_ to avoid code duplication between ESP32 and host platforms
   inline void HOT format_buffered_message_and_notify_(uint8_t level, const char *tag, uint16_t line,
                                                       const char *thread_name, const char *text, uint16_t text_length,
                                                       LogBuffer &buf) {
@@ -359,15 +392,8 @@ class Logger final : public Component {
 #ifdef USE_HOST
   pthread_t main_thread_{};  // Main thread for pthread_equal() comparison
 #endif
-#ifdef USE_ESP32
-  // Task-specific recursion guards:
-  // - Main task uses a dedicated member variable for efficiency
-  // - Other tasks use pthread TLS with a dynamically created key via pthread_key_create
-  pthread_key_t log_recursion_key_;  // 4 bytes
-  uart_port_t uart_num_;             // 4 bytes (enum defaults to int size)
-#endif
-#ifdef USE_HOST
-  // Thread-specific recursion guards using pthread TLS
+#if defined(USE_ESP32) || defined(USE_HOST)
+  // Non-main task recursion guard (pthread TLS)
   pthread_key_t log_recursion_key_;
 #endif
 
@@ -392,23 +418,10 @@ class Logger final : public Component {
   bool boot_log_done_{false};     // Set on first replay; stops further capture
 #endif
   uint8_t current_level_{ESPHOME_LOG_LEVEL_VERY_VERBOSE};
-#if defined(USE_ESP32) || defined(USE_ESP8266) || defined(USE_RP2) || defined(USE_ZEPHYR)
-  UARTSelection uart_{UART_SELECTION_UART0};  // Must match cpp_default_uart in __init__.py
-#endif
-#ifdef USE_LIBRETINY
-  UARTSelection uart_{UART_SELECTION_DEFAULT};  // Must match cpp_default_uart in __init__.py
-#endif
-#if defined(USE_ESP32) || defined(USE_HOST) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR)
-  bool main_task_recursion_guard_{false};
+  bool main_task_recursion_guard_{false};  // Guards tx_buffer_ on the main loop
 #ifdef USE_LIBRETINY
   bool non_main_task_recursion_guard_{false};  // Shared guard for all non-main tasks on LibreTiny
 #endif
-  // The guard that protects tx_buffer_ on the main loop, for callers that run on any platform
-  bool &main_loop_recursion_guard_() { return this->main_task_recursion_guard_; }
-#else
-  bool global_recursion_guard_{false};  // Simple global recursion guard for single-task platforms
-  bool &main_loop_recursion_guard_() { return this->global_recursion_guard_; }
-#endif
 
   // Large buffers placed last to keep frequently-accessed member offsets small
   char tx_buffer_[ESPHOME_LOGGER_TX_BUFFER_SIZE + 1];  // +1 for null terminator
@@ -477,9 +490,9 @@ class Logger final : public Component {
   class NonMainTaskRecursionGuard {
    public:
     explicit NonMainTaskRecursionGuard(pthread_key_t key) : key_(key) {
-      pthread_setspecific(key_, reinterpret_cast<void *>(1));
+      pthread_setspecific(this->key_, reinterpret_cast<void *>(1));
     }
-    ~NonMainTaskRecursionGuard() { pthread_setspecific(key_, nullptr); }
+    ~NonMainTaskRecursionGuard() { pthread_setspecific(this->key_, nullptr); }
     NonMainTaskRecursionGuard(const NonMainTaskRecursionGuard &) = delete;
     NonMainTaskRecursionGuard &operator=(const NonMainTaskRecursionGuard &) = delete;
     NonMainTaskRecursionGuard(NonMainTaskRecursionGuard &&) = delete;
@@ -490,40 +503,24 @@ class Logger final : public Component {
   };
 
   // Check if non-main task is already in recursion (via TLS)
-  inline bool HOT is_non_main_task_recursive_() const { return pthread_getspecific(log_recursion_key_) != nullptr; }
+  inline bool HOT is_non_main_task_recursive_() const {
+    return pthread_getspecific(this->log_recursion_key_) != nullptr;
+  }
 
   // Create RAII guard for non-main task recursion
-  inline NonMainTaskRecursionGuard make_non_main_task_guard_() { return NonMainTaskRecursionGuard(log_recursion_key_); }
-
-#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
-  // This is safe because:
-  // - 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_; }
-
-  // Create RAII guard for non-main task recursion (uses shared boolean for all non-main tasks)
-  inline RecursionGuard make_non_main_task_guard_() { return RecursionGuard(non_main_task_recursion_guard_); }
-#endif
-
-#if defined(USE_ESPHOME_TASK_LOG_BUFFER) && !(defined(USE_ZEPHYR) && defined(USE_LOGGER_UART_SELECTION_USB_CDC))
-  // Disable loop when task buffer is empty
-  // Zephyr with USB CDC needs loop active to poll port readiness via cdc_loop_()
-  inline void disable_loop_when_buffer_empty_() {
-    // Thread safety note: This is safe even if another task calls enable_loop_soon_any_context()
-    // concurrently. If that happens between our check and disable_loop(), the enable request
-    // will be processed on the next main loop iteration since:
-    // - disable_loop() takes effect immediately
-    // - enable_loop_soon_any_context() sets a pending flag that's checked at loop start
-    this->disable_loop();
+  inline NonMainTaskRecursionGuard make_non_main_task_guard_() {
+    return NonMainTaskRecursionGuard(this->log_recursion_key_);
   }
+
+#elif defined(USE_LIBRETINY)
+  // No FreeRTOS TLS on LibreTiny: all non-main tasks share one guard
+  inline bool HOT is_non_main_task_recursive_() const { return this->non_main_task_recursion_guard_; }
+  inline RecursionGuard make_non_main_task_guard_() { return RecursionGuard(this->non_main_task_recursion_guard_); }
+
+#elif defined(USE_ZEPHYR)
+  // Thread-local guard (__thread)
+  inline bool HOT is_non_main_task_recursive_() const { return non_main_task_recursion_guard; }
+  inline RecursionGuard make_non_main_task_guard_() { return RecursionGuard(non_main_task_recursion_guard); }
 #endif
 };
 extern Logger *global_logger;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
@@ -563,14 +560,7 @@ void log_crash_to_client();
 
 }  // namespace esphome::logger
 
-// Platform-specific inline implementations of write_msg_()
-// Must be included after the Logger class definition is complete
-#if defined(USE_ESP32)
+// ESP32 inline write_msg_(), included after the Logger class definition is complete
+#ifdef USE_ESP32
 #include "logger_esp32.h"
-#elif defined(USE_ESP8266)
-#include "logger_esp8266.h"
-#elif defined(USE_RP2)
-#include "logger_rp2.h"
-#elif defined(USE_LIBRETINY)
-#include "logger_libretiny.h"
 #endif

esphome/components/logger/logger_esp32.cpp

@@ -17,6 +17,9 @@
 #include <driver/usb_serial_jtag_vfs.h>
 #endif
 #endif
+#if defined(USE_LOGGER_CONSOLE) && defined(USE_LOGGER_UART_SELECTION_USB_CDC) && defined(CONFIG_ESP_CONSOLE_USB_CDC)
+#include <esp_private/usb_console.h>
+#endif
 #if defined(CONFIG_PM_ENABLE) && defined(CONFIG_FREERTOS_USE_TICKLESS_IDLE) && \
     (ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(6, 0, 0))
 #include "esp_sleep.h"
@@ -73,7 +76,8 @@ static void init_usb_serial_jtag() {
 }
 #endif
 
-void init_uart(uart_port_t uart_num, uint32_t baud_rate, int tx_buffer_size) {
+#if !defined(USE_LOGGER_UART_SELECTION_USB_CDC) && !defined(USE_LOGGER_UART_SELECTION_USB_SERIAL_JTAG)
+static void init_uart(uart_port_t uart_num, uint32_t baud_rate, int tx_buffer_size) {
   uart_config_t uart_config{};
   uart_config.baud_rate = (int) baud_rate;
   uart_config.data_bits = UART_DATA_8_BITS;
@@ -97,37 +101,22 @@ void init_uart(uart_port_t uart_num, uint32_t baud_rate, int tx_buffer_size) {
   esp_sleep_set_console_uart_handling_mode(ESP_SLEEP_ALWAYS_FLUSH_UART);
 #endif
 }
+#endif
+
+// get_uart_num() and pre_setup() cast the selection straight to a port
+static_assert(static_cast<int>(UART_SELECTION_UART0) == static_cast<int>(UART_NUM_0) &&
+              static_cast<int>(UART_SELECTION_UART1) == static_cast<int>(UART_NUM_1));
+#ifdef USE_ESP32_VARIANT_ESP32
+static_assert(static_cast<int>(UART_SELECTION_UART2) == static_cast<int>(UART_NUM_2));
+#endif
 
 void Logger::pre_setup() {
   if (this->baud_rate_ > 0) {
-    this->uart_num_ = UART_NUM_0;
-    switch (this->uart_) {
-      case UART_SELECTION_UART0:
-        this->uart_num_ = UART_NUM_0;
-        init_uart(this->uart_num_, baud_rate_, ESPHOME_LOGGER_TX_BUFFER_SIZE);
-        break;
-      case UART_SELECTION_UART1:
-        this->uart_num_ = UART_NUM_1;
-        init_uart(this->uart_num_, baud_rate_, ESPHOME_LOGGER_TX_BUFFER_SIZE);
-        break;
-#ifdef USE_ESP32_VARIANT_ESP32
-      case UART_SELECTION_UART2:
-        this->uart_num_ = UART_NUM_2;
-        init_uart(this->uart_num_, baud_rate_, ESPHOME_LOGGER_TX_BUFFER_SIZE);
-        break;
-#endif
-#ifdef USE_LOGGER_USB_CDC
-      case UART_SELECTION_USB_CDC:
-        break;
-#endif
-#ifdef USE_LOGGER_USB_SERIAL_JTAG
-      case UART_SELECTION_USB_SERIAL_JTAG:
 #ifdef USE_LOGGER_UART_SELECTION_USB_SERIAL_JTAG
-        init_usb_serial_jtag();
+    init_usb_serial_jtag();
+#elif !defined(USE_LOGGER_UART_SELECTION_USB_CDC)
+    init_uart(this->get_uart_num(), this->baud_rate_, ESPHOME_LOGGER_TX_BUFFER_SIZE);
 #endif
-        break;
-#endif
-    }
   }
 
   global_logger = this;
@@ -139,29 +128,36 @@ void Logger::pre_setup() {
 #endif
 }
 
-const LogString *Logger::get_uart_selection_() {
-  switch (this->uart_) {
-    case UART_SELECTION_UART0:
-      return LOG_STR("UART0");
-    case UART_SELECTION_UART1:
-      return LOG_STR("UART1");
-#ifdef USE_ESP32_VARIANT_ESP32
-    case UART_SELECTION_UART2:
-      return LOG_STR("UART2");
+#ifdef USE_LOGGER_CONSOLE
+size_t Logger::console_write(const uint8_t *data, size_t len) {
+  int written = 0;
+#if defined(USE_LOGGER_UART_SELECTION_USB_CDC)
+#ifdef CONFIG_ESP_CONSOLE_USB_CDC
+  written = esp_usb_console_write_buf(reinterpret_cast<const char *>(data), len);
 #endif
-#ifdef USE_LOGGER_USB_CDC
-    case UART_SELECTION_USB_CDC:
-      return LOG_STR("USB_CDC");
+#elif defined(USE_LOGGER_UART_SELECTION_USB_SERIAL_JTAG)
+  written = usb_serial_jtag_write_bytes(data, len, 20 / portTICK_PERIOD_MS);
+#else
+  written = uart_write_bytes(this->get_uart_num(), data, len);
 #endif
-#ifdef USE_LOGGER_USB_SERIAL_JTAG
-    case UART_SELECTION_USB_SERIAL_JTAG:
-      return LOG_STR("USB_SERIAL_JTAG");
-#endif
-    default:
-      return LOG_STR("UNKNOWN");
-  }
+  return written > 0 ? written : 0;
 }
 
+bool Logger::console_read(uint8_t &byte) {
+#if defined(USE_LOGGER_UART_SELECTION_USB_CDC)
+#ifdef CONFIG_ESP_CONSOLE_USB_CDC
+  return esp_usb_console_available_for_read() && esp_usb_console_read_buf(reinterpret_cast<char *>(&byte), 1) == 1;
+#else
+  return false;
+#endif
+#elif defined(USE_LOGGER_UART_SELECTION_USB_SERIAL_JTAG)
+  return usb_serial_jtag_read_bytes(&byte, 1, 0) > 0;
+#else
+  return uart_read_bytes(this->get_uart_num(), &byte, 1, 0) > 0;
+#endif
+}
+#endif
+
 #ifdef USE_CRASH_HANDLER
 bool crash_log_pending() { return esp32::crash_handler_has_data(); }
 void log_crash_to_client() {

esphome/components/logger/logger_esp32.h

@@ -19,7 +19,7 @@ inline void HOT Logger::write_msg_(const char *msg, uint16_t len) {
   fwrite(msg, 1, len, stdout);
 #else
   // Regular UART - single write including newline (already in buffer)
-  uart_write_bytes(this->uart_num_, msg, len);
+  uart_write_bytes(this->get_uart_num(), msg, len);
 #endif
 }
 

esphome/components/logger/logger_esp8266.cpp

@@ -14,9 +14,9 @@ void Logger::pre_setup() {
 #if defined(USE_ESP8266_LOGGER_SERIAL)
   this->hw_serial_ = &Serial;
   Serial.begin(this->baud_rate_);
-  if (this->uart_ == UART_SELECTION_UART0_SWAP) {
-    Serial.swap();
-  }
+#ifdef USE_LOGGER_UART_SELECTION_UART0_SWAP
+  Serial.swap();
+#endif
   Serial.setDebugOutput(ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE);
 #elif defined(USE_ESP8266_LOGGER_SERIAL1)
   this->hw_serial_ = &Serial1;
@@ -35,19 +35,6 @@ void Logger::pre_setup() {
 #endif
 }
 
-const LogString *Logger::get_uart_selection_() {
-#if defined(USE_ESP8266_LOGGER_SERIAL)
-  if (this->uart_ == UART_SELECTION_UART0_SWAP) {
-    return LOG_STR("UART0_SWAP");
-  }
-  return LOG_STR("UART0");
-#elif defined(USE_ESP8266_LOGGER_SERIAL1)
-  return LOG_STR("UART1");
-#else
-  return LOG_STR("NONE");
-#endif
-}
-
 #ifdef USE_CRASH_HANDLER
 bool crash_log_pending() { return esp8266::crash_handler_has_data(); }
 void log_crash_to_client() { esp8266::crash_handler_log(); }

esphome/components/logger/logger_esp8266.h

@@ -1,13 +0,0 @@
-#pragma once
-
-#ifdef USE_ESP8266
-#include "esphome/core/helpers.h"
-
-namespace esphome::logger {
-
-// Single write with newline already in buffer (added by caller)
-inline void HOT Logger::write_msg_(const char *msg, uint16_t len) { this->hw_serial_->write(msg, len); }
-
-}  // namespace esphome::logger
-
-#endif

esphome/components/logger/logger_libretiny.cpp

@@ -12,45 +12,28 @@ ESPHOME_LOG_TAG(TAG, "logger");
 
 void Logger::pre_setup() {
   if (this->baud_rate_ > 0) {
-    switch (this->uart_) {
-#if LT_HW_UART0
-      case UART_SELECTION_UART0:
-        this->hw_serial_ = &Serial0;
-        libretiny::ensure_serial_handle(0);
-        Serial0.begin(this->baud_rate_);
-        break;
-#endif
-#if LT_HW_UART1
-      case UART_SELECTION_UART1:
-        this->hw_serial_ = &Serial1;
-        libretiny::ensure_serial_handle(1);
-        Serial1.begin(this->baud_rate_);
-        break;
-#endif
-#if LT_HW_UART2
-      case UART_SELECTION_UART2:
-        this->hw_serial_ = &Serial2;
-        libretiny::ensure_serial_handle(2);
-        Serial2.begin(this->baud_rate_);
-        break;
-#endif
-      default:
-        this->hw_serial_ = &Serial;
-        Serial.begin(this->baud_rate_);
-        if (this->uart_ != UART_SELECTION_DEFAULT) {
-          ESP_LOGW(TAG, "  The chosen logger UART port is not available on this board."
-                        "The default port was used instead.");
-        }
-        break;
+#if defined(USE_LOGGER_UART_SELECTION_UART0) && LT_HW_UART0
+    this->hw_serial_ = &Serial0;
+    libretiny::ensure_serial_handle(0);
+    Serial0.begin(this->baud_rate_);
+#elif defined(USE_LOGGER_UART_SELECTION_UART1) && LT_HW_UART1
+    this->hw_serial_ = &Serial1;
+    libretiny::ensure_serial_handle(1);
+    Serial1.begin(this->baud_rate_);
+#elif defined(USE_LOGGER_UART_SELECTION_UART2) && LT_HW_UART2
+    this->hw_serial_ = &Serial2;
+    libretiny::ensure_serial_handle(2);
+    Serial2.begin(this->baud_rate_);
+#else
+    this->hw_serial_ = &Serial;
+    Serial.begin(this->baud_rate_);
+    if (CONFIGURED_UART_SELECTION != UART_SELECTION_DEFAULT) {
+      ESP_LOGW(TAG, "  The chosen logger UART port is not available on this board."
+                    "The default port was used instead.");
     }
-
+#endif
     // change lt_log() port to match default Serial
-    if (this->uart_ == UART_SELECTION_DEFAULT) {
-      this->uart_ = (UARTSelection) (LT_UART_DEFAULT_SERIAL + 1);
-      lt_log_set_port(LT_UART_DEFAULT_SERIAL);
-    } else {
-      lt_log_set_port(this->uart_ - 1);
-    }
+    lt_log_set_port(this->get_uart() - 1);
   }
 
   global_logger = this;
@@ -60,20 +43,6 @@ void Logger::pre_setup() {
 #endif
 }
 
-const LogString *Logger::get_uart_selection_() {
-  switch (this->uart_) {
-    case UART_SELECTION_DEFAULT:
-      return LOG_STR("DEFAULT");
-    case UART_SELECTION_UART0:
-      return LOG_STR("UART0");
-    case UART_SELECTION_UART1:
-      return LOG_STR("UART1");
-    case UART_SELECTION_UART2:
-    default:
-      return LOG_STR("UART2");
-  }
-}
-
 #ifdef USE_LIBRETINY_CRASH_HANDLER
 bool crash_log_pending() { return libretiny::crash_handler_has_data(); }
 void log_crash_to_client() { libretiny::crash_handler_log(); }

esphome/components/logger/logger_libretiny.h

@@ -1,13 +0,0 @@
-#pragma once
-
-#ifdef USE_LIBRETINY
-#include "esphome/core/helpers.h"
-
-namespace esphome::logger {
-
-// Single write with newline already in buffer (added by caller)
-inline void HOT Logger::write_msg_(const char *msg, uint16_t len) { this->hw_serial_->write(msg, len); }
-
-}  // namespace esphome::logger
-
-#endif

esphome/components/logger/logger_rp2.cpp

@@ -26,20 +26,16 @@ void Logger::setup() {
 
 void Logger::pre_setup() {
   if (this->baud_rate_ > 0) {
-    switch (this->uart_) {
-      case UART_SELECTION_UART0:
-        this->hw_serial_ = &Serial1;
-        Serial1.begin(this->baud_rate_);
-        break;
-      case UART_SELECTION_UART1:
-        this->hw_serial_ = &Serial2;
-        Serial2.begin(this->baud_rate_);
-        break;
-      case UART_SELECTION_USB_CDC:
-        this->hw_serial_ = &Serial;
-        Serial.begin(this->baud_rate_);
-        break;
-    }
+#if defined(USE_LOGGER_UART_SELECTION_USB_CDC)
+    this->hw_serial_ = &Serial;
+    Serial.begin(this->baud_rate_);
+#elif defined(USE_LOGGER_UART_SELECTION_UART1)
+    this->hw_serial_ = &Serial2;
+    Serial2.begin(this->baud_rate_);
+#else
+    this->hw_serial_ = &Serial1;
+    Serial1.begin(this->baud_rate_);
+#endif
   }
   global_logger = this;
   ESP_LOGI(TAG, "Log initialized");
@@ -49,21 +45,6 @@ void Logger::pre_setup() {
 #endif
 }
 
-const LogString *Logger::get_uart_selection_() {
-  switch (this->uart_) {
-    case UART_SELECTION_UART0:
-      return LOG_STR("UART0");
-    case UART_SELECTION_UART1:
-      return LOG_STR("UART1");
-#ifdef USE_LOGGER_USB_CDC
-    case UART_SELECTION_USB_CDC:
-      return LOG_STR("USB_CDC");
-#endif
-    default:
-      return LOG_STR("UNKNOWN");
-  }
-}
-
 #ifdef USE_CRASH_HANDLER
 bool crash_log_pending() { return rp2::crash_handler_has_data(); }
 void log_crash_to_client() { rp2::crash_handler_log(); }

esphome/components/logger/logger_rp2.h

@@ -1,13 +0,0 @@
-#pragma once
-
-#ifdef USE_RP2
-#include "esphome/core/helpers.h"
-
-namespace esphome::logger {
-
-// Single write with newline already in buffer (added by caller)
-inline void HOT Logger::write_msg_(const char *msg, uint16_t len) { this->hw_serial_->write(msg, len); }
-
-}  // namespace esphome::logger
-
-#endif

esphome/components/logger/logger_zephyr.cpp

@@ -42,9 +42,9 @@ __attribute__((section(".noinit"))) struct {
 
 ESPHOME_LOG_TAG(TAG, "logger");
 
-#ifdef USE_LOGGER_UART_SELECTION_USB_CDC
+#ifdef USE_LOGGER_ZEPHYR_CDC_LOOP
 void Logger::cdc_loop_() {
-  if (this->uart_ != UART_SELECTION_USB_CDC || this->uart_dev_ == nullptr) {
+  if (this->uart_dev_ == nullptr) {
     return;
   }
   static bool opened = false;
@@ -74,26 +74,20 @@ void Logger::cdc_loop_() {
 void Logger::pre_setup() {
 #ifdef CONFIG_SERIAL
   if (this->baud_rate_ > 0) {
-    static const struct device *uart_dev = nullptr;
-    switch (this->uart_) {
-      case UART_SELECTION_UART0:  // NOLINT(bugprone-branch-clone)
-        uart_dev = DEVICE_DT_GET_OR_NULL(DT_NODELABEL(ESPHOME_LOGGER_UART0_NODE));
-        break;
-      case UART_SELECTION_UART1:
-        uart_dev = DEVICE_DT_GET_OR_NULL(DT_NODELABEL(uart1));
-        break;
-#ifdef USE_LOGGER_USB_CDC
-      case UART_SELECTION_USB_CDC:
+    const struct device *uart_dev = nullptr;
+#if defined(USE_LOGGER_UART_SELECTION_USB_CDC)
 #if defined(CONFIG_USB_DEVICE_STACK) || defined(CONFIG_USB_DEVICE_STACK_NEXT)
-        uart_dev = DEVICE_DT_GET_OR_NULL(DT_NODELABEL(cdc_acm_uart0));
-        if (device_is_ready(uart_dev)) {
-          // Nothing can log this early, and the logger has no output without USB anyway
-          zephyr::usb_device_enable();
-        }
-#endif
-        break;
-#endif
+    uart_dev = DEVICE_DT_GET_OR_NULL(DT_NODELABEL(cdc_acm_uart0));
+    if (device_is_ready(uart_dev)) {
+      // Nothing can log this early, and the logger has no output without USB anyway
+      zephyr::usb_device_enable();
     }
+#endif
+#elif defined(USE_LOGGER_UART_SELECTION_UART1)
+    uart_dev = DEVICE_DT_GET_OR_NULL(DT_NODELABEL(uart1));
+#else
+    uart_dev = DEVICE_DT_GET_OR_NULL(DT_NODELABEL(ESPHOME_LOGGER_UART0_NODE));
+#endif
     if (device_is_ready(uart_dev)) {
       this->uart_dev_ = uart_dev;
 #if defined(USE_LOGGER_WAIT_FOR_CDC) && defined(USE_LOGGER_UART_SELECTION_USB_CDC)
@@ -114,14 +108,10 @@ void Logger::pre_setup() {
   char reason_buffer[zephyr::RESET_REASON_BUFFER_SIZE];
   const char *reset_reason = zephyr::get_reset_reason(std::span<char, zephyr::RESET_REASON_BUFFER_SIZE>(reason_buffer));
   ESP_LOGI(TAG, "Reset reason: %s", reset_reason);
-  dump_crash_();
+  this->dump_crash_();
 #endif
-#ifdef USE_CRASH_HANDLER
-#ifdef USE_LOGGER_UART_SELECTION_USB_CDC
   // Nobody reads a USB port this early; cdc_loop_() reports the dump once the port is opened
-  if (this->uart_ == UART_SELECTION_USB_CDC)
-    return;
-#endif
+#if defined(USE_CRASH_HANDLER) && !defined(USE_LOGGER_ZEPHYR_CDC_LOOP)
   // Without a UART (baud_rate: 0, or one that did not come up) nothing reaches the console
   if (this->uart_dev_ != nullptr)
     log_crash_to_client();
@@ -143,22 +133,7 @@ void HOT Logger::write_msg_(const char *msg, uint16_t len) {
   }
 }
 
-const LogString *Logger::get_uart_selection_() {
-  switch (this->uart_) {
-    case UART_SELECTION_UART0:
-      return LOG_STR("UART0");
-    case UART_SELECTION_UART1:
-      return LOG_STR("UART1");
-#ifdef USE_LOGGER_USB_CDC
-    case UART_SELECTION_USB_CDC:
-      return LOG_STR("USB_CDC");
-#endif
-    default:
-      return LOG_STR("UNKNOWN");
-  }
-}
-
-static const uint8_t REASON_BUF_SIZE = 32;
+static constexpr uint8_t REASON_BUF_SIZE = 32;
 
 static const char *reason_to_str(unsigned int reason, char *buf) {
   switch (reason) {

esphome/components/logger/task_log_buffer_esp32.cpp

@@ -44,19 +44,15 @@ void TaskLogBuffer::release_message_main_loop() {
 
 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)
+  // Measure on a copy; the caller's va_list formats the text later
   va_list args_copy;
   va_copy(args_copy, args);
-  int ret = vsnprintf(nullptr, 0, format, args_copy);
+  int ret = task_log_cap_length(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;
+  uint16_t text_length = ret;
 
   // Calculate total size needed (header + text length + null terminator)
   size_t total_size = sizeof(LogMessage) + text_length + 1;
@@ -69,24 +65,10 @@ bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uin
     return false;  // Failed to acquire memory
   }
 
-  // Set up the message header in the acquired memory
   LogMessage *msg = static_cast<LogMessage *>(acquired_memory);
-  msg->level = level;
-  msg->tag = tag;
-  msg->line = line;
-
-  // Store the thread name now instead of waiting until main loop processing
-  // This avoids crashes if the task completes or is deleted between when this message
-  // is enqueued and when it's processed by the main loop
-  if (thread_name != nullptr) {
-    strncpy(msg->thread_name, thread_name, sizeof(msg->thread_name) - 1);
-    msg->thread_name[sizeof(msg->thread_name) - 1] = '\0';  // Ensure null termination
-  } else {
-    msg->thread_name[0] = '\0';  // Empty string if no thread name
-  }
+  fill_task_log_header(msg, level, tag, line, thread_name);
 
   // 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);
 
@@ -96,12 +78,7 @@ bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uin
     return false;
   }
 
-  // Remove trailing newlines
-  while (text_length > 0 && text_area[text_length - 1] == '\n') {
-    text_length--;
-  }
-
-  msg->text_length = text_length;
+  msg->text_length = trim_trailing_newlines(text_area, text_length);
   // Complete the send operation with the acquired memory
   result = xRingbufferSendComplete(this->handle_(), acquired_memory);
 

esphome/components/logger/task_log_buffer_esp32.h

@@ -12,6 +12,8 @@
 #include <freertos/FreeRTOS.h>
 #include <freertos/ringbuf.h>
 
+#include "task_log_message.h"
+
 namespace esphome::logger {
 
 /**
@@ -32,19 +34,7 @@ namespace esphome::logger {
  */
 class TaskLogBuffer {
  public:
-  // Structure for a log message header (text data follows immediately after)
-  struct LogMessage {
-    const char *tag;       // We store the pointer, assuming tags are static
-    char thread_name[16];  // Store thread name directly (only used for non-main threads)
-    uint16_t text_length;  // Length of the message text (up to ~64KB)
-    uint16_t line;         // Source code line number
-    uint8_t level;         // Log level (0-7)
-
-    // Methods for accessing message contents
-    inline char *text_data() { return reinterpret_cast<char *>(this) + sizeof(LogMessage); }
-
-    inline const char *text_data() const { return reinterpret_cast<const char *>(this) + sizeof(LogMessage); }
-  };
+  using LogMessage = TaskLogMessage;
 
   TaskLogBuffer();
   // No destructor: Logger is never destroyed

esphome/components/logger/task_log_buffer_host.cpp

@@ -71,18 +71,8 @@ bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uin
 
   LogMessage &msg = this->slots_[slot_index];
 
-  // Fill in the message header
-  msg.level = level;
-  msg.tag = tag;
-  msg.line = line;
-
-  // Store the thread name now to avoid crashes if thread exits before processing
-  if (thread_name != nullptr) {
-    strncpy(msg.thread_name, thread_name, sizeof(msg.thread_name) - 1);
-    msg.thread_name[sizeof(msg.thread_name) - 1] = '\0';
-  } else {
-    msg.thread_name[0] = '\0';
-  }
+  // Copied now; the thread may exit before processing
+  fill_task_log_header(&msg, level, tag, line, thread_name);
 
   // Format the message text
   int ret = vsnprintf(msg.text, sizeof(msg.text), format, args);
@@ -94,10 +84,7 @@ bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uin
     msg.text_length = static_cast<uint16_t>(std::min(static_cast<size_t>(ret), sizeof(msg.text) - 1));
   }
 
-  // Remove trailing newlines
-  while (msg.text_length > 0 && msg.text[msg.text_length - 1] == '\n') {
-    msg.text_length--;
-  }
+  msg.text_length = trim_trailing_newlines(msg.text, msg.text_length);
   msg.text[msg.text_length] = '\0';
 
   // Commit the slot

esphome/components/logger/task_log_buffer_host.h

@@ -13,6 +13,8 @@
 #include <cstring>
 #include <pthread.h>
 
+#include "task_log_message.h"
+
 namespace esphome::logger {
 
 /**

esphome/components/logger/task_log_buffer_libretiny.cpp

@@ -13,13 +13,6 @@ TaskLogBuffer::TaskLogBuffer() {
   this->mutex_ = xSemaphoreCreateMutex();
 }
 
-TaskLogBuffer::~TaskLogBuffer() {
-  if (this->mutex_ != nullptr) {
-    vSemaphoreDelete(this->mutex_);
-    this->mutex_ = nullptr;
-  }
-}
-
 size_t TaskLogBuffer::available_contiguous_space_() const {
   if (this->head_ >= this->tail_) {
     // head is ahead of or equal to tail
@@ -85,19 +78,15 @@ void TaskLogBuffer::release_message_main_loop() {
 
 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)
+  // Measure on a copy; the caller's va_list formats the text later
   va_list args_copy;
   va_copy(args_copy, args);
-  int ret = vsnprintf(nullptr, 0, format, args_copy);
+  int ret = task_log_cap_length(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;
+  uint16_t text_length = ret;
 
   // Calculate total size needed (header + text length + null terminator)
   size_t total_size = message_total_size(text_length);
@@ -128,17 +117,7 @@ bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uin
 
   // Write message header
   LogMessage *msg = reinterpret_cast<LogMessage *>(this->storage_ + write_pos);
-  msg->level = level;
-  msg->tag = tag;
-  msg->line = line;
-
-  // Store the thread name now to avoid crashes if task is deleted before processing
-  if (thread_name != nullptr) {
-    strncpy(msg->thread_name, thread_name, sizeof(msg->thread_name) - 1);
-    msg->thread_name[sizeof(msg->thread_name) - 1] = '\0';
-  } else {
-    msg->thread_name[0] = '\0';
-  }
+  fill_task_log_header(msg, level, tag, line, thread_name);
 
   // Format the message text directly into the buffer
   char *text_area = msg->text_data();
@@ -150,9 +129,7 @@ bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uin
   }
 
   // Trim before storing so the next message reuses the freed bytes
-  while (text_length > 0 && text_area[text_length - 1] == '\n') {
-    text_length--;
-  }
+  text_length = trim_trailing_newlines(text_area, text_length);
   text_area[text_length] = '\0';
   msg->text_length = text_length;
 

esphome/components/logger/task_log_buffer_libretiny.h

@@ -13,6 +13,8 @@
 #include <semphr.h>
 #include <task.h>
 
+#include "task_log_message.h"
+
 namespace esphome::logger {
 
 /**
@@ -42,25 +44,14 @@ namespace esphome::logger {
  */
 class TaskLogBuffer {
  public:
-  // Structure for a log message header (text data follows immediately after)
-  struct LogMessage {
-    const char *tag;       // We store the pointer, assuming tags are static
-    char thread_name[16];  // Store thread name directly (only used for non-main threads)
-    uint16_t text_length;  // Length of the message text (up to ~64KB)
-    uint16_t line;         // Source code line number
-    uint8_t level;         // Log level (0-7)
-
-    // Methods for accessing message contents
-    inline char *text_data() { return reinterpret_cast<char *>(this) + sizeof(LogMessage); }
-    inline const char *text_data() const { return reinterpret_cast<const char *>(this) + sizeof(LogMessage); }
-  };
+  using LogMessage = TaskLogMessage;
 
   // Padding marker level to indicate wrap-around point (stored in LogMessage.level field)
   // Valid log levels are 0-7, so 0xFF cannot be a real message
   static constexpr uint8_t PADDING_MARKER_LEVEL = 0xFF;
 
   TaskLogBuffer();
-  ~TaskLogBuffer();
+  // No destructor: Logger is never destroyed
 
   // NOT thread-safe - borrow a message from the buffer, only call from main loop
   bool borrow_message_main_loop(LogMessage *&message, uint16_t &text_length);

esphome/components/logger/task_log_buffer_zephyr.cpp

@@ -4,7 +4,7 @@
 
 namespace esphome::logger {
 
-__thread bool non_main_task_recursion_guard_;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+__thread bool non_main_task_recursion_guard;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 
 #ifdef USE_ESPHOME_TASK_LOG_BUFFER
 
@@ -29,29 +29,21 @@ TaskLogBuffer::TaskLogBuffer() {
 
 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)
+  // Measure on a copy; the caller's va_list formats the text later
   va_list args_copy;
   va_copy(args_copy, args);
-  int ret = vsnprintf(nullptr, 0, format, args_copy);
+  int ret = task_log_cap_length(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;
+  uint16_t text_length = 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
+  fill_task_log_header(msg, level, tag, line, thread_name);
 
   // Format the message text directly into the acquired memory
   // We add 1 to text_length to ensure space for null terminator during formatting
@@ -90,11 +82,7 @@ bool TaskLogBuffer::borrow_message_main_loop(LogMessage *&message, uint16_t &tex
   // 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--;
-  }
+  text_length = trim_trailing_newlines(message->text_data(), message->text_length);
 
   return true;
 }

esphome/components/logger/task_log_buffer_zephyr.h

@@ -6,12 +6,14 @@
 #include "esphome/core/helpers.h"
 #include <zephyr/sys/mpsc_pbuf.h>
 
+#include "task_log_message.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)
+extern __thread bool non_main_task_recursion_guard;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 
 #ifdef USE_ESPHOME_TASK_LOG_BUFFER
 
@@ -34,7 +36,6 @@ class TaskLogBuffer {
     inline char *text_data() { return reinterpret_cast<char *>(this) + sizeof(LogMessage); }
   };
   TaskLogBuffer();
-  ~TaskLogBuffer() = default;
 
   // 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_); }

esphome/components/logger/task_log_message.h

@@ -0,0 +1,54 @@
+#pragma once
+
+#include "esphome/core/defines.h"
+
+#ifdef USE_ESPHOME_TASK_LOG_BUFFER
+#include <cstdarg>
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+#include <cstring>
+
+namespace esphome::logger {
+
+#if defined(USE_ESP32) || defined(USE_LIBRETINY)
+// Header of a variable-size task log message; the text follows it
+struct TaskLogMessage {
+  const char *tag;       // We store the pointer, assuming tags are static
+  char thread_name[16];  // Copied, the task may be gone before the main loop reads it
+  uint16_t text_length;
+  uint16_t line;
+  uint8_t level;
+
+  inline char *text_data() { return reinterpret_cast<char *>(this) + sizeof(TaskLogMessage); }
+};
+#endif
+
+#if defined(USE_ESP32) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR)
+static constexpr int TASK_LOG_MAX_TEXT_SIZE = 255;
+
+inline int task_log_cap_length(int ret) { return ret > TASK_LOG_MAX_TEXT_SIZE ? TASK_LOG_MAX_TEXT_SIZE : ret; }
+#endif
+
+template<typename Message>
+inline void fill_task_log_header(Message *msg, uint8_t level, const char *tag, uint16_t line, const char *thread_name) {
+  msg->level = level;
+  msg->tag = tag;
+  msg->line = line;
+  if (thread_name != nullptr) {
+    strncpy(msg->thread_name, thread_name, sizeof(msg->thread_name) - 1);
+    msg->thread_name[sizeof(msg->thread_name) - 1] = '\0';
+  } else {
+    msg->thread_name[0] = '\0';
+  }
+}
+
+inline uint16_t trim_trailing_newlines(const char *text, uint16_t length) {
+  while (length > 0 && text[length - 1] == '\n')
+    length--;
+  return length;
+}
+
+}  // namespace esphome::logger
+
+#endif  // USE_ESPHOME_TASK_LOG_BUFFER

esphome/components/web_server/__init__.py

@@ -614,25 +614,9 @@ async def to_code(config: ConfigType) -> None:
 
 
 def FILTER_SOURCE_FILES() -> list[str]:
-    """Filter out web_server_v1.cpp when version is not 1, the ESP32 event stream elsewhere, and the server on host."""
+    """Filter out web_server_v1.cpp when version is not 1."""
     files_to_filter: list[str] = []
 
-    # The host has no web server; it builds only sse_chunk.cpp, for its unit tests
-    if CORE.is_host:
-        files_to_filter.extend(
-            (
-                "event_source.cpp",
-                "list_entities.cpp",
-                "web_server.cpp",
-                "web_server_v1.cpp",
-            )
-        )
-        return files_to_filter
-
-    # The /events implementation is ESP32 only
-    if not CORE.is_esp32:
-        files_to_filter.extend(("event_source.cpp", "sse_chunk.cpp"))
-
     # web_server_v1.cpp is only needed when version is 1
     config = CORE.config.get(DOMAIN, {})
     if config.get(CONF_VERSION, 2) != 1:

esphome/components/web_server/event_source.cpp

@@ -1,491 +0,0 @@
-#include "event_source.h"
-#if defined(USE_ESP32) && defined(USE_WEBSERVER)
-
-#include <algorithm>
-#include <cstring>
-#include <iterator>
-
-#include "esphome/core/application.h"
-#include "esphome/core/helpers.h"
-#include "esphome/core/log.h"
-#include "web_server.h"
-
-namespace esphome::web_server {
-
-ESPHOME_LOG_TAG(TAG, "web_server_idf");
-
-// Only prepare_json_() may hold the JSON arena: every other frame in this file is capped below one
-// arena. Measured at -Os on GCC 14; newer toolchains stay checked on purpose, older ones skip it.
-#if defined(__GNUC__) && !defined(__clang__) && __GNUC__ >= 14 && defined(__OPTIMIZE_SIZE__)
-#pragma GCC diagnostic error "-Wstack-usage=2048"
-#endif
-
-AsyncEventSource::~AsyncEventSource() {
-  LockGuard guard{this->pending_mutex_};
-  for (auto *vec : {&this->sessions_, &this->pending_sessions_}) {
-    for (auto *ses : *vec) {
-      delete ses;  // NOLINT(cppcoreguidelines-owning-memory)
-    }
-  }
-}
-
-void AsyncEventSource::handleRequest(AsyncWebServerRequest *request) {
-  // Httpd task: set up the live httpd_req_t and park the session; main loop does the rest.
-  // NOLINTNEXTLINE(cppcoreguidelines-owning-memory,clang-analyzer-cplusplus.NewDeleteLeaks)
-  auto *rsp = new AsyncEventSourceResponse(request, this, this->web_server_);
-  {
-    LockGuard guard{this->pending_mutex_};
-    this->pending_sessions_.push_back(rsp);
-    this->has_pending_sessions_.store(true, std::memory_order_release);
-  }
-  this->web_server_->enable_loop_soon_any_context();
-}
-
-// clang-analyzer traces a false-positive leak path from loop() through
-// adopt_pending_sessions_main_loop_() into start_session_main_loop_() and
-// finally ArduinoJson. Suppress along the entire in-our-code call chain.
-// NOLINTBEGIN(clang-analyzer-cplusplus.NewDeleteLeaks)
-bool AsyncEventSource::loop() {
-  // Fast path: one atomic load per tick. Slow path is out-of-line on connect.
-  if (this->has_pending_sessions_.load(std::memory_order_acquire)) {
-    this->adopt_pending_sessions_main_loop_();
-  }
-
-  // Clean up dead sessions safely
-  // This follows the ESP-IDF pattern where free_ctx marks resources as dead
-  // and the main loop handles the actual cleanup to avoid race conditions
-  for (size_t i = 0; i < this->sessions_.size();) {
-    auto *ses = this->sessions_[i];
-    // If the session has a dead socket (marked by destroy callback)
-    if (ses->safe_to_delete()) {
-      // destroy() already logged the close with the fd; don't double-log here.
-      delete ses;  // NOLINT(cppcoreguidelines-owning-memory)
-      // Remove by swapping with last element (O(1) removal, order doesn't matter for sessions)
-      this->sessions_[i] = this->sessions_.back();
-      this->sessions_.pop_back();
-    } else {
-      ses->loop();
-      ++i;
-    }
-  }
-  // A session still waiting for httpd to commit its context keeps the loop alive too
-  return !this->sessions_.empty() || this->has_pending_sessions_.load(std::memory_order_acquire);
-}
-
-void AsyncEventSource::adopt_pending_sessions_main_loop_() {
-  std::vector<AsyncEventSourceResponse *> incoming;
-  {
-    LockGuard guard{this->pending_mutex_};
-    incoming.swap(this->pending_sessions_);
-    this->has_pending_sessions_.store(false, std::memory_order_relaxed);
-  }
-  for (auto *rsp : incoming) {
-    // Already disconnected? Drop it; skip session start on a dead session.
-    if (rsp->safe_to_delete()) {
-      delete rsp;  // NOLINT(cppcoreguidelines-owning-memory)
-      continue;
-    }
-    // httpd commits the session context only after the creating handler returns, so stay
-    // pending until then; httpd_req_cleanup() always commits it or calls destroy()
-    if (!rsp->is_attached()) {
-      LockGuard guard{this->pending_mutex_};
-      this->pending_sessions_.push_back(rsp);
-      this->has_pending_sessions_.store(true, std::memory_order_release);
-      continue;
-    }
-    this->sessions_.push_back(rsp);
-    rsp->start_session_main_loop_();
-  }
-}
-// NOLINTEND(clang-analyzer-cplusplus.NewDeleteLeaks)
-
-void AsyncEventSource::try_send_nodefer(const char *message, size_t message_len, const char *event, uint32_t id,
-                                        uint32_t reconnect) {
-  for (auto *ses : this->sessions_) {
-    if (ses->is_connected()) {
-      ses->try_send_nodefer(message, message_len, event, id, reconnect);
-    }
-  }
-}
-
-void AsyncEventSource::deferrable_send_state(void *source, bool detail_all, message_generator_t *message_generator) {
-  // Skip if no connected clients to avoid unnecessary processing
-  if (this->empty())
-    return;
-  for (auto *ses : this->sessions_) {
-    if (ses->is_connected()) {
-      ses->deferrable_send_state(source, detail_all, message_generator);
-    }
-  }
-}
-
-AsyncEventSourceResponse::AsyncEventSourceResponse(AsyncWebServerRequest *request, AsyncEventSource *server,
-                                                   WebServer *ws)
-    : server_(server), web_server_(ws), entities_iterator_(ws, this) {
-  // Httpd task only. start_session_main_loop_() sends the greeting and starts the iterator.
-  this->begin(request, SSE_STATUS, SSE_CONTENT_TYPE, SSE_HEADERS, SSE_FIRST_CHUNK);
-}
-static_assert(web_server_base::stream_head_iov_count(std::size(SSE_HEADERS) + WEB_SERVER_DEFAULT_HEADERS_COUNT) <=
-                  web_server_base::STREAM_HEAD_MAX_IOV,
-              "the event stream head must go out in one write");
-
-// NOLINTBEGIN(clang-analyzer-cplusplus.NewDeleteLeaks) false positive with ArduinoJson
-void AsyncEventSourceResponse::start_session_main_loop_() {
-  auto *ws = this->web_server_;
-
-  // The tcp send buffer is empty on connect. A refusal is a closing session or a failed tail
-  // allocation; nothing retries the greeting, so close and let the client reconnect.
-  auto message = ws->get_config_json();
-  if (!this->try_send_nodefer(message.c_str(), message.size(), "ping", millis(), 30000)) {
-    ESP_LOGW(TAG, "Config not sent to fd %d", this->log_id());
-    this->close();
-    return;
-  }
-
-#ifdef USE_WEBSERVER_SORTING
-  for (auto &group : ws->sorting_groups_) {
-    json::JsonBuilder builder;
-    JsonObject root = builder.root();
-    root["name"] = json::linked(group.second.name);
-    root["sorting_weight"] = group.second.weight;
-    message = builder.serialize();
-
-    // a (very) large number of these should be able to be queued initially without defer
-    // since the only thing in the send buffer at this point is the initial ping/config.
-    // A refusal means the socket is full or closing; the remaining groups are not sent. The
-    // session stays up on purpose: partial grouping beats a reconnect loop on a slow link.
-    if (!this->try_send_nodefer(message.c_str(), message.size(), "sorting_group")) {
-      ESP_LOGW(TAG, "Sorting groups not sent to fd %d", this->log_id());
-      break;
-    }
-  }
-#endif
-
-  this->entities_iterator_.begin(ws->include_internal_);
-}
-// NOLINTEND(clang-analyzer-cplusplus.NewDeleteLeaks)
-
-// helper for allowing only unique entries in the queue
-void AsyncEventSourceResponse::deq_push_back_with_dedup_(void *source, message_generator_t *message_generator) {
-  DeferredEvent item(source, message_generator);
-
-  // Use range-based for loop instead of std::find_if to reduce template instantiation overhead and binary size
-  for (auto &event : this->deferred_queue_) {
-    if (event == item) {
-      return;  // Already in queue, no need to update since items are equal
-    }
-  }
-  this->deferred_queue_.push_back(item);
-}
-
-void AsyncEventSourceResponse::process_deferred_queue_() {
-  if (this->is_closing()) {
-    return;
-  }
-  while (!deferred_queue_.empty()) {
-    DeferredEvent &de = deferred_queue_.front();
-    if (this->send_json_(de.source_, de.message_generator_)) {
-      if (this->is_closing() || deferred_queue_.empty()) {
-        return;
-      }
-      // O(n) but memory efficiency is more important than speed here which is why std::vector was chosen
-      deferred_queue_.erase(deferred_queue_.begin());
-    } else {
-      break;
-    }
-  }
-}
-
-void AsyncEventSourceResponse::release_buffers_() {
-  std::vector<DeferredEvent>().swap(this->deferred_queue_);
-  this->tail_.reset();
-  this->tail_cap_ = 0;
-  this->tail_len_ = 0;
-  this->tail_sent_ = 0;
-}
-
-void AsyncEventSourceResponse::drain_tail_() {
-  if (this->sending_ || this->is_closing() || this->tail_len_ == 0) {
-    return;
-  }
-  SendGuard guard{*this};
-
-  const size_t remaining = this->tail_len_ - this->tail_sent_;
-  const ssize_t sent = this->write(this->tail_.get() + this->tail_sent_, remaining);
-  if (sent <= 0) {
-    return;  // write() owns the stall clock and the close
-  }
-  this->no_memory_logged_ = false;
-  this->tail_sent_ += sent;
-  if (this->tail_sent_ < this->tail_len_) {
-    ESP_LOGV(TAG, "Partial send: %zd/%zu bytes (total: %u/%u)", sent, remaining, this->tail_sent_, this->tail_len_);
-    return;
-  }
-  // Fully sent; the storage stays for the next stall
-  this->tail_len_ = 0;
-}
-
-bool AsyncEventSourceResponse::reserve_tail_(size_t len) {
-  if (this->tail_cap_ >= len) {
-    return true;
-  }
-  if (len > TAIL_MAX_SIZE) {
-    return false;
-  }
-  // Nothing is pending while the tail grows, so free the old block first. PREFER_INTERNAL keeps
-  // the tail where plain new put it.
-  this->tail_.reset();
-  this->tail_ = RAMAllocator<uint8_t>(RAMAllocator<uint8_t>::PREFER_INTERNAL).make_unique_array_for_overwrite(len);
-  this->tail_cap_ = this->tail_ ? len : 0;
-  return this->tail_cap_ != 0;
-}
-
-bool AsyncEventSourceResponse::stash_chunk_(const char *prefix, size_t prefix_len, const char *message,
-                                            size_t message_len, size_t total, size_t sent) {
-  // A log event of nothing but line breaks is the largest chunk; reserve_tail_() must never
-  // refuse it for size, only for memory
-  static_assert(SSE_SEP_LEN * LOG_EVENT_MAX_LEN + PREFIX_BUF_SIZE + SSE_SUFFIX_LEN <= TAIL_MAX_SIZE,
-                "the log cut in web_server.h must keep a worst case log event inside the tail ceiling");
-  if (!this->reserve_tail_(total)) {
-    if (sent != 0) {
-      // Part of the chunk is on the wire, so the stream is broken and the client has to go
-      ESP_LOGW(TAG, "Cannot buffer a %zu byte chunk, closing", total);
-      this->close();
-    } else {
-      this->tail_alloc_failed_(total);  // nothing on the wire, the caller retries on the stall clock
-    }
-    return false;
-  }
-  uint8_t *dst = this->tail_.get();
-  std::memcpy(dst, prefix, prefix_len);
-  dst += prefix_len;
-  for_each_chunk_piece(
-      message, message_len,
-      [](void *ctx, const char *piece, size_t len) {
-        auto &out = *static_cast<uint8_t **>(ctx);
-        std::memcpy(out, piece, len);
-        out += len;
-      },
-      &dst);
-  this->tail_len_ = total;
-  this->tail_sent_ = sent;
-  return true;
-}
-
-void AsyncEventSourceResponse::loop() {
-  AsyncStreamResponse::loop();
-  if (this->is_closing()) {
-    if (this->tail_cap_ != 0 || this->deferred_queue_.capacity() != 0) {
-      this->release_buffers_();
-    }
-    return;
-  }
-  drain_tail_();
-  process_deferred_queue_();
-  if (this->is_closing())
-    return;
-  // One step per loop; refusals retry next pass
-  this->entities_iterator_.try_advance(1);
-}
-
-#if defined(__GNUC__) && !defined(__clang__) && __GNUC__ >= 14 && defined(__OPTIMIZE_SIZE__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wstack-usage="  // the one frame that holds the JSON arena
-#endif
-AsyncEventSourceResponse::JsonPrepareResult AsyncEventSourceResponse::prepare_json_(void *source,
-                                                                                    message_generator_t *generator,
-                                                                                    char *buffer, size_t *size_out) {
-  // Log lines emitted while the generator runs are dropped for this session: on the large path they would fill
-  // tail_ before it is overwritten, and on the small path they would go out ahead of the event being built.
-  SendGuard guard{*this};
-  json::JsonArena<json::JSON_ARENA_SIZE> arena;
-  json::JsonBuilder builder(&arena);
-  generator(this->web_server_, source, builder);
-  *size_out = builder.serialize_to(buffer, JSON_BUF_SIZE);
-  if (*size_out < JSON_BUF_SIZE) {
-    return JsonPrepareResult::JSON_PREPARE_RESULT_BUFFER;
-  }
-
-  char prefix[PREFIX_BUF_SIZE];
-  const size_t prefix_len = build_chunk_prefix(prefix, sizeof(prefix), "state", 0, 0, true);
-
-  // Nothing reaches the wire until the complete document and its framing are owned by the caller.
-  size_t json_len = 0;
-  size_t cap = std::max<size_t>(JSON_BUF_SIZE * 2, this->tail_cap_);
-  for (;;) {
-    if (!this->reserve_tail_(cap)) {
-      *size_out = cap;
-      return JsonPrepareResult::JSON_PREPARE_RESULT_NO_MEMORY;
-    }
-    const size_t room = cap - prefix_len - SSE_SUFFIX_LEN;
-    json_len = builder.serialize_to(reinterpret_cast<char *>(this->tail_.get()) + prefix_len, room);
-    if (json_len < room) {
-      break;
-    }
-    if (cap >= TAIL_MAX_SIZE) {
-      *size_out = room;
-      return JsonPrepareResult::JSON_PREPARE_RESULT_TOO_LARGE;
-    }
-    cap = std::min<size_t>(cap * 2, TAIL_MAX_SIZE);
-  }
-
-  const size_t total = prefix_len + json_len + SSE_SUFFIX_LEN;
-  write_chunk_header(prefix, total - CHUNK_HDR_LEN - CHUNK_END_LEN);
-  uint8_t *dst = this->tail_.get();
-  std::memcpy(dst, prefix, prefix_len);
-  std::memcpy(dst + prefix_len + json_len, SSE_SUFFIX, SSE_SUFFIX_LEN);
-  this->tail_len_ = total;
-  this->tail_sent_ = 0;
-  return JsonPrepareResult::JSON_PREPARE_RESULT_TAIL;
-}
-#if defined(__GNUC__) && !defined(__clang__) && __GNUC__ >= 14 && defined(__OPTIMIZE_SIZE__)
-#pragma GCC diagnostic pop
-#endif
-
-bool AsyncEventSourceResponse::send_json_(void *source, message_generator_t *generator) {
-  if (!this->ready_to_send_()) {
-    return false;
-  }
-  char buffer[JSON_BUF_SIZE];
-  size_t size;
-  const auto result = this->prepare_json_(source, generator, buffer, &size);
-  switch (result) {
-    case JsonPrepareResult::JSON_PREPARE_RESULT_BUFFER:
-      return this->try_send_nodefer(buffer, size, "state");
-    case JsonPrepareResult::JSON_PREPARE_RESULT_TAIL:
-      this->drain_tail_();
-      return true;
-    case JsonPrepareResult::JSON_PREPARE_RESULT_NO_MEMORY: {
-      SendGuard guard{*this};
-      this->tail_alloc_failed_(size);
-      return false;
-    }
-    case JsonPrepareResult::JSON_PREPARE_RESULT_TOO_LARGE: {
-      SendGuard guard{*this};
-      ESP_LOGW(TAG, "State event does not fit %zu bytes, dropped", size);
-      this->tail_.reset();
-      this->tail_cap_ = 0;
-      this->stall_.clear();
-      this->no_memory_logged_ = false;
-      return true;
-    }
-  }
-  return false;
-}
-
-void AsyncEventSourceResponse::tail_alloc_failed_(size_t cap) {
-  // Same stall clock as a socket that stops draining, so a session cannot retry forever. A refused write may
-  // already have started it, so the warning keeps its own flag.
-  if (!this->no_memory_logged_) {
-    this->no_memory_logged_ = true;
-    ESP_LOGW(TAG, "No memory for a %zu byte chunk", cap);
-  }
-  const uint32_t now = App.get_loop_component_start_time();
-  if (!this->stall_.is_running()) {
-    this->stall_.start(now);
-    return;
-  }
-  if (this->stall_.is_expired(now, SEND_STALL_TIMEOUT_MS)) {
-    ESP_LOGW(TAG, "Closing EventSource after %" PRIu32 " ms without memory", this->stall_.elapsed(now));
-    this->close();
-  }
-}
-
-bool AsyncEventSourceResponse::ready_to_send_() {
-  if (this->sending_ || !this->is_connected() || this->is_closing()) {
-    return false;
-  }
-  drain_tail_();
-  return !this->is_closing() && this->tail_len_ == 0;
-}
-
-bool AsyncEventSourceResponse::try_send_nodefer(const char *message, size_t message_len, const char *event, uint32_t id,
-                                                uint32_t reconnect) {
-  if (!this->ready_to_send_()) {
-    return false;
-  }
-  SendGuard guard{*this};
-
-  // Everything after the prefix goes out straight from the caller's buffer
-  char prefix[PREFIX_BUF_SIZE];
-  const size_t prefix_len = build_chunk_prefix(prefix, sizeof(prefix), event, id, reconnect, message != nullptr);
-  if (message == nullptr && prefix_len == CHUNK_HDR_LEN) {
-    return true;  // Match ESPAsyncWebServer: nothing to send
-  }
-  if (prefix_len >= PREFIX_BUF_SIZE - 1) {
-    // The appenders truncate silently, which would put a malformed event on the wire
-    ESP_LOGW(TAG, "Event name too long, dropped");
-    return true;
-  }
-
-  // Gather list: the prefix, then the data lines and their separators from the message
-  struct Gather {
-    web_server_base::StreamIovec iov[MAX_SEND_IOV];  // left uninitialized on purpose
-    int iovcnt{1};
-    size_t total{0};
-    bool fits{true};
-  } g;
-  g.total = prefix_len;
-  for_each_chunk_piece(
-      message, message_len,
-      [](void *ctx, const char *piece, size_t len) {
-        auto &g = *static_cast<Gather *>(ctx);
-        g.total += len;
-        if (len == 0) {
-          return;
-        }
-        if (g.iovcnt == MAX_SEND_IOV) {
-          g.fits = false;
-          return;
-        }
-        g.iov[g.iovcnt++] = {const_cast<char *>(piece), len};
-      },
-      &g);
-  // The header and the terminator are not part of the chunk length
-  write_chunk_header(prefix, g.total - CHUNK_HDR_LEN - CHUNK_END_LEN);
-  g.iov[0] = {prefix, prefix_len};
-
-  // A message with more lines than the list holds skips straight to the tail
-  const ssize_t sent = g.fits ? this->write(g.iov, g.iovcnt) : 0;
-  if (sent < 0) {
-    return false;
-  }
-  if (sent > 0) {
-    this->no_memory_logged_ = false;
-  }
-  if (static_cast<size_t>(sent) == g.total) {
-    return true;
-  }
-  // The caller's buffers do not outlive this call, so keep the chunk and continue from loop()
-  return this->stash_chunk_(prefix, prefix_len, message, message_len, g.total, sent);
-}
-
-void AsyncEventSourceResponse::deferrable_send_state(void *source, bool detail_all,
-                                                     message_generator_t *message_generator) {
-  // Let the detail_all listing finish before bare state events, so the web UI never shows unnamed entries and
-  // initial connect sends less
-  if (!detail_all && !this->entities_iterator_.completed())
-    return;
-
-  drain_tail_();
-  process_deferred_queue_();
-
-  if (this->is_closing()) {
-    return;
-  }
-
-  if (this->tail_len_ != 0 || !deferred_queue_.empty()) {
-    // outgoing event buffer or deferred queue still not empty which means downstream tcp send buffer full, no point
-    // trying to send first
-    deq_push_back_with_dedup_(source, message_generator);
-  } else {
-    // A send error closes the session and clears the queue; nothing is queued after that
-    if (!this->send_json_(source, message_generator) && !this->is_closing()) {
-      deq_push_back_with_dedup_(source, message_generator);
-    }
-  }
-}
-
-}  // namespace esphome::web_server
-
-#endif  // USE_ESP32 && USE_WEBSERVER

esphome/components/web_server/event_source.h

@@ -1,176 +0,0 @@
-#pragma once
-
-#include "esphome/core/defines.h"
-#if defined(USE_ESP32) && defined(USE_WEBSERVER)
-
-#include "esphome/components/json/json_util.h"
-#include "esphome/components/web_server_base/stream_response.h"
-#include "esphome/core/helpers.h"
-#include "esphome/core/string_ref.h"
-#include "list_entities.h"
-#include "sse_chunk.h"
-
-#include <atomic>
-#include <cstdint>
-#include <vector>
-
-namespace esphome::web_server {
-
-class WebServer;
-class AsyncEventSource;
-class AsyncEventSourceResponse;
-
-using message_generator_t = void(WebServer *, void *, json::JsonBuilder &);
-
-/*
-  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 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 AsyncEventSourceResponse;
-
- protected:
-  void *source_;
-  message_generator_t *message_generator_;
-
- public:
-  DeferredEvent(void *source, message_generator_t *message_generator)
-      : source_(source), message_generator_(message_generator) {}
-  bool operator==(const DeferredEvent &test) const {
-    return (source_ == test.source_ && message_generator_ == test.message_generator_);
-  }
-};
-static_assert(sizeof(DeferredEvent) == sizeof(void *) + sizeof(message_generator_t *),
-              "DeferredEvent should have no padding");
-
-class AsyncEventSourceResponse : public web_server_base::AsyncStreamResponse {
-  friend class AsyncEventSource;
-
- public:
-  bool try_send_nodefer(const char *message, size_t message_len, const char *event = nullptr, uint32_t id = 0,
-                        uint32_t reconnect = 0);
-  // detail_all events go out while entities are still being listed; state events wait until listing is done
-  void deferrable_send_state(void *source, bool detail_all, message_generator_t *message_generator);
-  // The old event name argument would otherwise convert to true
-  void deferrable_send_state(void *source, const char *event_type, message_generator_t *message_generator) = delete;
-  void loop();
-
- protected:
-  AsyncEventSourceResponse(AsyncWebServerRequest *request, AsyncEventSource *server, WebServer *ws);
-
-  // Main-loop only: sends initial ping/config/sorting_groups, starts entity iterator.
-  void start_session_main_loop_();
-
-  void deq_push_back_with_dedup_(void *source, message_generator_t *message_generator);
-  void process_deferred_queue_();
-  // A new chunk may go out: not re-entered from a log line, session alive, tail empty
-  bool ready_to_send_();
-  // Push what is left of the chunk in tail_ to the socket
-  void drain_tail_();
-  // Grow tail_ to hold len bytes, kept at its high-water mark. False on OOM.
-  bool reserve_tail_(size_t len);
-  // Keep the whole chunk in tail_ and continue from sent; false when the tail cannot be allocated.
-  bool stash_chunk_(const char *prefix, size_t prefix_len, const char *message, size_t message_len, size_t total,
-                    size_t sent);
-  // Send a state event; JSON too large for the stack buffer is serialized into tail_ instead
-  bool send_json_(void *source, message_generator_t *generator);
-  enum class JsonPrepareResult : uint8_t {
-    JSON_PREPARE_RESULT_BUFFER,
-    JSON_PREPARE_RESULT_TAIL,
-    JSON_PREPARE_RESULT_NO_MEMORY,
-    JSON_PREPARE_RESULT_TOO_LARGE,
-  };
-  // Keep the arena out of the caller's frame so it is gone before the state send.
-  // size_out: BUFFER = JSON length, NO_MEMORY = requested tail capacity, TOO_LARGE = available JSON room;
-  // unused for TAIL.
-  JsonPrepareResult __attribute__((noinline)) prepare_json_(void *source, message_generator_t *generator, char *buffer,
-                                                            size_t *size_out);
-  // Warn once per stall, and close the session once the stall timeout passes with no memory for the tail
-  void tail_alloc_failed_(size_t cap);
-
-  // A log line emitted inside a send re-enters try_send_nodefer on this session; refuse it
-  struct SendGuard {
-    AsyncEventSourceResponse &owner;
-    explicit SendGuard(AsyncEventSourceResponse &owner) : owner(owner) { owner.sending_ = true; }
-    ~SendGuard() { this->owner.sending_ = false; }
-  };
-  // Frees the tail and the queue's storage once the session is closing
-  void release_buffers_();
-
-  AsyncEventSource *server_;
-  std::vector<DeferredEvent> deferred_queue_;
-  WebServer *web_server_;
-  ListEntitiesIterator entities_iterator_;
-  // One chunk the socket did not take whole, allocated on the first stall; the only heap use
-  // on the send path
-  RAMUniquePtr<uint8_t[]> tail_;
-  uint16_t tail_cap_{0};
-  uint16_t tail_len_{0};  // Zero means nothing pending
-  uint16_t tail_sent_{0};
-  bool sending_{false};
-  // The no-memory warning went out during the current stall; cleared on send progress
-  bool no_memory_logged_{false};
-  // The longest multi line log message in the tree (a climate dump_config) has 22 lines; a
-  // longer one goes through the tail
-  static constexpr size_t MAX_SEND_LINES = 22;
-  static constexpr size_t MAX_SEND_IOV = 1 + 2 * MAX_SEND_LINES;
-  // Chunk header, retry/id/event lines and the first "data: "
-  static constexpr size_t PREFIX_BUF_SIZE = 128;
-
-  // Stack buffer for a state event's JSON; a larger document is serialized into the tail
-  static constexpr size_t JSON_BUF_SIZE = 1024;
-  // Same ceiling JsonBuilder::serialize() applies (max_heap_size in json_util.cpp); a larger
-  // document is dropped before anything is on the wire
-  static constexpr size_t JSON_MAX_SIZE = 5120;
-  // Most RAM a stalled session keeps: the largest state document plus any accepted framing
-  static constexpr size_t TAIL_MAX_SIZE = JSON_MAX_SIZE + PREFIX_BUF_SIZE + SSE_SUFFIX_LEN;
-};
-
-class AsyncEventSource : public AsyncWebHandler {
-  friend class AsyncEventSourceResponse;
-
- public:
-  AsyncEventSource(StringRef url, WebServer *ws) : url_(url), web_server_(ws) {}
-  ~AsyncEventSource() override;
-
-  // NOLINTNEXTLINE(readability-identifier-naming)
-  bool canHandle(AsyncWebServerRequest *request) const override {
-    if (request->method() != HTTP_GET)
-      return false;
-    char url_buf[AsyncWebServerRequest::URL_BUF_SIZE];
-    return request->url_to(url_buf) == this->url_;
-  }
-  // NOLINTNEXTLINE(readability-identifier-naming)
-  void handleRequest(AsyncWebServerRequest *request) override;
-  void try_send_nodefer(const char *message, size_t message_len, const char *event = nullptr, uint32_t id = 0,
-                        uint32_t reconnect = 0);
-  void deferrable_send_state(void *source, bool detail_all, message_generator_t *message_generator);
-  // The old event name argument would otherwise convert to true
-  void deferrable_send_state(void *source, const char *event_type, message_generator_t *message_generator) = delete;
-  /// Returns true if there are sessions remaining (including pending cleanup).
-  bool loop();
-  bool empty() { return this->count() == 0; }
-
-  size_t count() const { return this->sessions_.size(); }
-
- protected:
-  // Cold path: move sessions from pending_sessions_ into sessions_ and greet each one.
-  void __attribute__((noinline, cold)) adopt_pending_sessions_main_loop_();
-
-  StringRef url_;  // Must outlive this object (string literal)
-  // Main-loop only. Vector: SSE sessions are 1-5 connections, linear search beats set.
-  std::vector<AsyncEventSourceResponse *> sessions_;
-  // Httpd-task intake; guarded by pending_mutex_, gated by has_pending_sessions_.
-  std::vector<AsyncEventSourceResponse *> pending_sessions_;
-  Mutex pending_mutex_;
-  WebServer *web_server_;
-  std::atomic<bool> has_pending_sessions_{false};
-};
-
-}  // namespace esphome::web_server
-
-#endif  // USE_ESP32 && USE_WEBSERVER

esphome/components/web_server/list_entities.cpp

@@ -8,8 +8,14 @@
 
 namespace esphome::web_server {
 
+#ifdef USE_ESP32
+ListEntitiesIterator::ListEntitiesIterator(const WebServer *ws, AsyncEventSource *es) : web_server_(ws), events_(es) {}
+#elif USE_ARDUINO
+ListEntitiesIterator::ListEntitiesIterator(const WebServer *ws, DeferredUpdateEventSource *es)
+    : web_server_(ws), events_(es) {}
+#endif
 void ListEntitiesIterator::send_all_(void *source, message_generator_t *generator) {
-  this->session_->deferrable_send_state(source, true, generator);
+  this->events_->deferrable_send_state(source, true, generator);
 }
 
 #ifdef USE_BINARY_SENSOR

esphome/components/web_server/list_entities.h

@@ -1,28 +1,33 @@
 #pragma once
 
 #include "esphome/core/defines.h"
-#if defined(USE_WEBSERVER) && (defined(USE_ESP32) || defined(USE_ARDUINO))
+#ifdef USE_WEBSERVER
 #include "esphome/core/component.h"
 #include "esphome/core/component_iterator.h"
 namespace esphome::json {
 class JsonBuilder;
 }  // namespace esphome::json
 
+namespace esphome::web_server_idf {
+#ifdef USE_ESP32
+class AsyncEventSource;
+#endif
+}  // namespace esphome::web_server_idf
+
 namespace esphome::web_server {
 
-// The /events session the iterator lists entities to
-#ifdef USE_ESP32
-class AsyncEventSourceResponse;
-using EventSession = AsyncEventSourceResponse;
-#elif defined(USE_ARDUINO)
+#if !defined(USE_ESP32) && defined(USE_ARDUINO)
 class DeferredUpdateEventSource;
-using EventSession = DeferredUpdateEventSource;
 #endif
 class WebServer;
 
 class ListEntitiesIterator final : public ComponentIterator {
  public:
-  ListEntitiesIterator(const WebServer *ws, EventSession *session) : web_server_(ws), session_(session) {}
+#ifdef USE_ESP32
+  ListEntitiesIterator(const WebServer *ws, esphome::web_server_idf::AsyncEventSource *es);
+#elif defined(USE_ARDUINO)
+  ListEntitiesIterator(const WebServer *ws, DeferredUpdateEventSource *es);
+#endif
 
 // Entity overrides (generated from entity_types.h).
 // Implementations live in list_entities.cpp.
@@ -40,7 +45,11 @@ class ListEntitiesIterator final : public ComponentIterator {
   void send_all_(void *source, void (*generator)(WebServer *, void *, json::JsonBuilder &));
 
   const WebServer *web_server_;
-  EventSession *session_;
+#ifdef USE_ESP32
+  esphome::web_server_idf::AsyncEventSource *events_;
+#elif USE_ARDUINO
+  DeferredUpdateEventSource *events_;
+#endif
 };
 
 }  // namespace esphome::web_server

esphome/components/web_server/web_server.cpp

@@ -245,7 +245,7 @@ void DeferredUpdateEventSource::process_deferred_queue_() {
       deferred_queue_.erase(deferred_queue_.begin());
       this->consecutive_send_failures_ = 0;  // Reset failure count on successful send
     } else {
-      // NOTE: Similar logic exists in web_server_idf/web_server_idf.cpp in AsyncStreamResponse::write().
+      // NOTE: Similar logic exists in web_server_idf/web_server_idf.cpp in AsyncEventSourceResponse::drain_tail_().
       // The close mechanisms are platform-specific (this path calls close() directly; the IDF path is time-based and
       // closes through HTTPD to preserve session ownership), but both drop a client after roughly 20 seconds without
       // send progress. Keep that stall policy in sync when changing either side.

esphome/components/web_server/web_server.h

@@ -5,11 +5,7 @@
 #include "esphome/components/json/json_util.h"
 #include "esphome/components/web_server_base/web_server_base.h"
 #include "esphome/components/web_server_base/captive_dns.h"
-// The host only builds sse_chunk.cpp for unit tests, but other tests can define USE_WEBSERVER there
-#if defined(USE_WEBSERVER) && (defined(USE_ESP32) || defined(USE_ARDUINO))
-#ifdef USE_ESP32
-#include "event_source.h"
-#endif
+#ifdef USE_WEBSERVER
 #include "esphome/core/component.h"
 #include "esphome/core/entity_base.h"
 #include "esphome/core/entity_includes.h"

esphome/components/web_server_base/__init__.py

@@ -105,9 +105,9 @@ async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     cg.add(cg.RawExpression(f"{web_server_base_ns}::global_web_server_base = {var}"))
 
-    # Default headers added in init(): web_server_idf's StaticVector, or the library's DefaultHeaders
-    cg.add_define("WEB_SERVER_DEFAULT_HEADERS_COUNT", 1)
     if CORE.is_esp32:
+        # Count for StaticVector in web_server_idf - matches headers added in init()
+        cg.add_define("WEB_SERVER_DEFAULT_HEADERS_COUNT", 1)
         return
 
     # ESP32 uses IDF web server (early return above), so this is for other Arduino platforms

esphome/components/web_server_base/stream_head.h

@@ -1,126 +0,0 @@
-#pragma once
-
-#include <cstddef>
-#include <cstdint>
-#include <cstring>
-#include <span>
-
-#include <strings.h>
-
-// Pure helpers of AsyncStreamResponse, kept free of httpd and lwIP so they build on the host.
-// The iovec type is a template parameter: lwIP defines its own on the device, POSIX on the host.
-
-namespace esphome::web_server_base {
-
-struct HttpHeader {
-  const char *name;
-  const char *value;
-};
-
-/// Drops the first sent bytes from a gather list after a write; a short write resumes inside the
-/// element it stopped in. count reaches 0 once everything went out.
-template<typename Iovec> void advance_iovecs(Iovec *&iov, int &count, size_t sent) {
-  while (count > 0 && sent >= iov->iov_len) {
-    sent -= iov->iov_len;
-    ++iov;
-    --count;
-  }
-  if (count > 0) {
-    iov->iov_base = static_cast<char *>(iov->iov_base) + sent;
-    iov->iov_len -= sent;
-  }
-}
-
-/// Pieces in a head: 4 for the status line and Content-Type, 4 per header, the blank line and the body
-constexpr size_t stream_head_iov_count(size_t header_count) { return 4 + 4 * header_count + 2; }
-
-/// Pieces per batch: a head with up to four headers goes out in one write; 192 bytes on 32-bit
-static constexpr int STREAM_HEAD_MAX_IOV = 24;
-
-/// True if headers holds a header named name, compared case insensitively
-inline bool has_header(std::span<const HttpHeader> headers, const char *name) {
-  for (const auto &header : headers) {
-    if (strcasecmp(header.name, name) == 0) {
-      return true;
-    }
-  }
-  return false;
-}
-
-/// Gathers the head of a stream response: "HTTP/1.1 <status>", Content-Type, headers, the default_headers that
-/// headers does not replace, the blank line and body (may be null). send(Iovec *iov, int count) gets each full batch of
-/// STREAM_HEAD_MAX_IOV pieces and then the rest; once it returns false the later pieces are skipped. Returns false if
-/// any send failed.
-template<typename Iovec, typename Send>
-bool write_stream_head(Send &&send, const char *status, const char *content_type, std::span<const HttpHeader> headers,
-                       std::span<const HttpHeader> default_headers, const char *body) {
-  struct Batch {
-    Send &send;
-    int count{0};
-    bool ok{true};
-    Iovec iov[STREAM_HEAD_MAX_IOV];  // left uninitialized on purpose
-
-    void flush() {
-      if (this->ok && this->count > 0) {
-        this->ok = this->send(this->iov, this->count);
-      }
-      this->count = 0;
-    }
-    void add(const char *buf, size_t len) {
-      if (this->count == STREAM_HEAD_MAX_IOV) {
-        this->flush();
-      }
-      this->iov[this->count++] = {const_cast<char *>(buf), len};
-    }
-    void add(const char *str) { this->add(str, strlen(str)); }
-    void add_header(const HttpHeader &header) {
-      this->add("\r\n", 2);
-      this->add(header.name);
-      this->add(": ", 2);
-      this->add(header.value);
-    }
-  } batch{send};
-
-  batch.add("HTTP/1.1 ", 9);
-  batch.add(status);
-  batch.add("\r\nContent-Type: ", 16);
-  batch.add(content_type);
-  for (const auto &header : headers) {
-    batch.add_header(header);
-  }
-  for (const auto &header : default_headers) {
-    if (!has_header(headers, header.name)) {
-      batch.add_header(header);
-    }
-  }
-  batch.add("\r\n\r\n", 4);
-  if (body != nullptr) {
-    batch.add(body);
-  }
-  batch.flush();
-  return batch.ok;
-}
-
-/// How long sends have made no progress. Zero means not running, so a start at millis() == 0 records 1.
-/// The comparison is wraparound safe across a millis() rollover.
-class StallClock {
- public:
-  /// Starts the clock; a running clock keeps its start time.
-  void start(uint32_t now) {
-    if (this->started_ms_ == 0) {
-      this->started_ms_ = now != 0 ? now : 1;
-    }
-  }
-  void clear() { this->started_ms_ = 0; }
-  bool is_running() const { return this->started_ms_ != 0; }
-  /// True once the clock has run for timeout_ms
-  bool is_expired(uint32_t now, uint32_t timeout_ms) const {
-    return this->started_ms_ != 0 && static_cast<int32_t>(now - (this->started_ms_ + timeout_ms)) >= 0;
-  }
-  uint32_t elapsed(uint32_t now) const { return now - this->started_ms_; }
-
- protected:
-  uint32_t started_ms_{0};
-};
-
-}  // namespace esphome::web_server_base

esphome/components/web_server_base/stream_response.h

@@ -1,16 +0,0 @@
-#pragma once
-
-#include "esphome/core/defines.h"
-
-// The long lived stream response the /events layer writes to, for the platform's web server
-#ifdef USE_ESP32
-#include "esphome/components/web_server_idf/web_server_idf.h"
-
-#include <sys/socket.h>
-
-namespace esphome::web_server_base {
-using web_server_idf::AsyncStreamResponse;
-// One entry of the gather list AsyncStreamResponse::write() takes
-using StreamIovec = ::iovec;
-}  // namespace esphome::web_server_base
-#endif

esphome/components/web_server_idf/sse_chunk.cpp

@@ -5,7 +5,7 @@
 
 #include "esphome/core/helpers.h"
 
-namespace esphome::web_server {
+namespace esphome::web_server_idf {
 
 void for_each_chunk_piece(const char *message, size_t message_len, ChunkPieceSink sink, void *ctx) {
   if (message == nullptr) {
@@ -63,4 +63,4 @@ void write_chunk_header(char *buf, size_t chunk_len) {
   buf[9] = '\n';
 }
 
-}  // namespace esphome::web_server
+}  // namespace esphome::web_server_idf

esphome/components/web_server_idf/sse_chunk.h

@@ -3,9 +3,7 @@
 #include <cstddef>
 #include <cstdint>
 
-#include "esphome/components/web_server_base/stream_head.h"
-
-namespace esphome::web_server {
+namespace esphome::web_server_idf {
 
 // Wire framing of one Server-Sent-Events event inside the chunked /events response:
 //   "%08x\r\n" + fields + "data: " line ["\r\ndata: " line]... "\r\n" + "\r\n" + "\r\n"
@@ -24,17 +22,6 @@ constexpr size_t SSE_SEP_LEN = sizeof(SSE_SEP) - 1;
 constexpr char SSE_SUFFIX[] = "\r\n\r\n\r\n";
 constexpr size_t SSE_SUFFIX_LEN = sizeof(SSE_SUFFIX) - 1;
 
-// Status, Content-Type and headers of the /events response head
-constexpr char SSE_STATUS[] = "200 OK";
-constexpr char SSE_CONTENT_TYPE[] = "text/event-stream";
-constexpr web_server_base::HttpHeader SSE_HEADERS[] = {
-    {"Transfer-Encoding", "chunked"},
-    {"Cache-Control", "no-cache"},
-    {"Connection", "keep-alive"},
-};
-// Hand-framed first chunk holding an empty event (one blank line), as httpd_resp_send_chunk() sent it before
-constexpr char SSE_FIRST_CHUNK[] = "2\r\n\r\n\r\n";
-
 // Receives one piece of the chunk; ctx is whatever the caller passed to for_each_chunk_piece()
 using ChunkPieceSink = void (*)(void *ctx, const char *piece, size_t len);
 
@@ -50,4 +37,4 @@ size_t build_chunk_prefix(char *buf, size_t size, const char *event, uint32_t id
 // Fills the header placeholder at the start of buf once the chunk length is known
 void write_chunk_header(char *buf, size_t chunk_len);
 
-}  // namespace esphome::web_server
+}  // namespace esphome::web_server_idf

esphome/components/web_server_idf/web_server_idf.cpp

@@ -17,6 +17,7 @@
 #include <freertos/task.h>
 
 #include "utils.h"
+#include "sse_chunk.h"
 #include "web_server_idf.h"
 
 #ifdef USE_WEBSERVER_AUTH_DIGEST
@@ -29,15 +30,17 @@
 #include "multipart.h"  // For parse_multipart_boundary and other utils
 #endif
 
+#ifdef USE_WEBSERVER
+#include "esphome/components/web_server/web_server.h"
+#include "esphome/components/web_server/list_entities.h"
+#endif  // USE_WEBSERVER
+
 // Include socket headers after Arduino headers to avoid IPADDR_NONE/INADDR_NONE macro conflicts
 #include <cerrno>
 #include <sys/socket.h>
 
 namespace esphome::web_server_idf {
 
-using web_server_base::advance_iovecs;
-using web_server_base::write_stream_head;
-
 // Status strings not provided by esp_http_server.h
 #ifndef HTTPD_401
 #define HTTPD_401 "401 Unauthorized"
@@ -52,10 +55,13 @@ using web_server_base::write_stream_head;
 #define HTTPD_422 "422 Unprocessable Entity"
 #endif
 
+#define CRLF_STR "\r\n"
+#define CRLF_LEN (sizeof(CRLF_STR) - 1)
+
 ESPHOME_LOG_TAG(TAG, "web_server_idf");
 
-// Every frame in this file is capped below one JSON arena.
-// Measured at -Os on GCC 14; newer toolchains stay checked on purpose, older ones skip it.
+// Only prepare_json_() may hold the JSON arena: every other frame in this file is capped below one
+// arena. Measured at -Os on GCC 14; newer toolchains stay checked on purpose, older ones skip it.
 #if defined(__GNUC__) && !defined(__clang__) && __GNUC__ >= 14 && defined(__OPTIMIZE_SIZE__)
 #pragma GCC diagnostic error "-Wstack-usage=2048"
 #endif
@@ -134,8 +140,6 @@ void AsyncWebServer::safe_close_with_shutdown(httpd_handle_t hd, int sockfd) {
   //
   // See: https://github.com/esphome/esphome-webserver/issues/163
 
-  AsyncStreamResponse::socket_closing(hd, sockfd);
-
   // Attempt shutdown - ignore errors as socket may already be closed
   shutdown(sockfd, SHUT_RD);
 
@@ -732,84 +736,224 @@ void AsyncResponseStream::printf(const char *fmt, ...) {
   this->print(str);
 }
 
-void AsyncStreamResponse::begin(AsyncWebServerRequest *request, const char *status, const char *content_type,
-                                std::span<const HttpHeader> headers, const char *body) {
-  httpd_req_t *req = *request;
-  // Same head httpd_resp_send_chunk() writes, without its first chunk. Blocking sends: the session's non-blocking
-  // send override is not installed yet.
-  const int fd = httpd_req_to_sockfd(req);
-  const auto &defaults = DefaultHeaders::Instance().headers_;
-  const bool head_sent = write_stream_head<struct iovec>(
-      [fd](struct iovec *iov, int count) {
-        while (count > 0) {
-          struct msghdr msg{};
-          msg.msg_iov = iov;
-          msg.msg_iovlen = count;
-          const ssize_t sent = sendmsg(fd, &msg, 0);
-          if (sent <= 0) {
-            return false;
-          }
-          advance_iovecs(iov, count, sent);
-        }
-        return true;
-      },
-      status, content_type, headers, std::span<const HttpHeader>(defaults.data(), defaults.size()), body);
-
-  req->sess_ctx = this;
-  req->free_ctx = AsyncStreamResponse::destroy;
-
-  this->hd_ = req->handle;
-  this->fd_.store(fd);
-
-  // Use non-blocking send to prevent watchdog timeouts when TCP buffers are full
-  httpd_sess_set_send_override(this->hd_, fd, nonblocking_send);
-
-  if (!head_sent) {
-    // A partly sent head must not be continued by later writes. close() is main loop only, so shut the socket
-    // down here; the first write() then fails and closes the stream, and httpd frees the session as usual.
-    shutdown(fd, SHUT_RDWR);
+#ifdef USE_WEBSERVER
+AsyncEventSource::~AsyncEventSource() {
+  LockGuard guard{this->pending_mutex_};
+  for (auto *vec : {&this->sessions_, &this->pending_sessions_}) {
+    for (auto *ses : *vec) {
+      delete ses;  // NOLINT(cppcoreguidelines-owning-memory)
+    }
   }
 }
 
-// Held around a stream's ownership check and send, and while its socket is marked closed.
-// Created at boot, so no allocation can fail once requests arrive.
-static Mutex stream_send_mutex;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
-
-void AsyncStreamResponse::socket_closing(httpd_handle_t hd, int fd) {
-  // Only streams set a session context
-  auto *rsp = static_cast<AsyncStreamResponse *>(httpd_sess_get_ctx(hd, fd));
-  if (rsp == nullptr)
-    return;
-  LockGuard guard{stream_send_mutex};
-  rsp->socket_closed_ = true;
+void AsyncEventSource::handleRequest(AsyncWebServerRequest *request) {
+  // Httpd task: set up the live httpd_req_t and park the session; main loop does the rest.
+  // NOLINTNEXTLINE(cppcoreguidelines-owning-memory,clang-analyzer-cplusplus.NewDeleteLeaks)
+  auto *rsp = new AsyncEventSourceResponse(request, this, this->web_server_);
+  {
+    LockGuard guard{this->pending_mutex_};
+    this->pending_sessions_.push_back(rsp);
+    this->has_pending_sessions_.store(true, std::memory_order_release);
+  }
+  this->web_server_->enable_loop_soon_any_context();
 }
 
-void AsyncStreamResponse::destroy(void *ptr) {
-  auto *rsp = static_cast<AsyncStreamResponse *>(ptr);
+// clang-analyzer traces a false-positive leak path from loop() through
+// adopt_pending_sessions_main_loop_() into start_session_main_loop_() and
+// finally ArduinoJson. Suppress along the entire in-our-code call chain.
+// NOLINTBEGIN(clang-analyzer-cplusplus.NewDeleteLeaks)
+bool AsyncEventSource::loop() {
+  // Fast path: one atomic load per tick. Slow path is out-of-line on connect.
+  if (this->has_pending_sessions_.load(std::memory_order_acquire)) {
+    this->adopt_pending_sessions_main_loop_();
+  }
+
+  // Clean up dead sessions safely
+  // This follows the ESP-IDF pattern where free_ctx marks resources as dead
+  // and the main loop handles the actual cleanup to avoid race conditions
+  for (size_t i = 0; i < this->sessions_.size();) {
+    auto *ses = this->sessions_[i];
+    // If the session has a dead socket (marked by destroy callback)
+    if (ses->safe_to_delete_()) {
+      // destroy() already logged the close with the fd; don't double-log here.
+      delete ses;  // NOLINT(cppcoreguidelines-owning-memory)
+      // Remove by swapping with last element (O(1) removal, order doesn't matter for sessions)
+      this->sessions_[i] = this->sessions_.back();
+      this->sessions_.pop_back();
+    } else {
+      ses->loop();
+      ++i;
+    }
+  }
+  // A session still waiting for httpd to commit its context keeps the loop alive too
+  return !this->sessions_.empty() || this->has_pending_sessions_.load(std::memory_order_acquire);
+}
+
+void AsyncEventSource::adopt_pending_sessions_main_loop_() {
+  std::vector<AsyncEventSourceResponse *> incoming;
+  {
+    LockGuard guard{this->pending_mutex_};
+    incoming.swap(this->pending_sessions_);
+    this->has_pending_sessions_.store(false, std::memory_order_relaxed);
+  }
+  for (auto *rsp : incoming) {
+    // Already disconnected? Drop it; skip session start on a dead session.
+    if (rsp->safe_to_delete_()) {
+      delete rsp;  // NOLINT(cppcoreguidelines-owning-memory)
+      continue;
+    }
+    // httpd commits the session context only after the creating handler returns, so stay
+    // pending until then; httpd_req_cleanup() always commits it or calls destroy()
+    if (httpd_sess_get_ctx(rsp->hd_, rsp->fd_.load()) != rsp) {
+      LockGuard guard{this->pending_mutex_};
+      this->pending_sessions_.push_back(rsp);
+      this->has_pending_sessions_.store(true, std::memory_order_release);
+      continue;
+    }
+    this->sessions_.push_back(rsp);
+    rsp->start_session_main_loop_();
+  }
+}
+// NOLINTEND(clang-analyzer-cplusplus.NewDeleteLeaks)
+
+void AsyncEventSource::try_send_nodefer(const char *message, size_t message_len, const char *event, uint32_t id,
+                                        uint32_t reconnect) {
+  for (auto *ses : this->sessions_) {
+    if (ses->fd_.load() != 0) {  // Skip dead sessions
+      ses->try_send_nodefer(message, message_len, event, id, reconnect);
+    }
+  }
+}
+
+void AsyncEventSource::deferrable_send_state(void *source, bool detail_all, message_generator_t *message_generator) {
+  // Skip if no connected clients to avoid unnecessary processing
+  if (this->empty())
+    return;
+  for (auto *ses : this->sessions_) {
+    if (ses->fd_.load() != 0) {  // Skip dead sessions
+      ses->deferrable_send_state(source, detail_all, message_generator);
+    }
+  }
+}
+
+AsyncEventSourceResponse::AsyncEventSourceResponse(const AsyncWebServerRequest *request,
+                                                   esphome::web_server_idf::AsyncEventSource *server,
+                                                   esphome::web_server::WebServer *ws)
+    : server_(server), web_server_(ws), entities_iterator_(ws, server) {
+  // Httpd task only. start_session_main_loop_() sends the greeting and starts the iterator.
+  httpd_req_t *req = *request;
+
+  httpd_resp_set_status(req, HTTPD_200);
+  httpd_resp_set_type(req, "text/event-stream");
+  httpd_resp_set_hdr(req, "Cache-Control", "no-cache");
+  httpd_resp_set_hdr(req, "Connection", "keep-alive");
+
+  DefaultHeaders::Instance().apply_(req);
+
+  httpd_resp_send_chunk(req, CRLF_STR, CRLF_LEN);
+
+  req->sess_ctx = this;
+  req->free_ctx = AsyncEventSourceResponse::destroy;
+
+  this->hd_ = req->handle;
+  this->fd_.store(httpd_req_to_sockfd(req));
+
+  // Use non-blocking send to prevent watchdog timeouts when TCP buffers are full
+  httpd_sess_set_send_override(this->hd_, this->fd_.load(), nonblocking_send);
+}
+
+// NOLINTBEGIN(clang-analyzer-cplusplus.NewDeleteLeaks) false positive with ArduinoJson
+void AsyncEventSourceResponse::start_session_main_loop_() {
+  auto *ws = this->web_server_;
+
+  // The tcp send buffer is empty on connect. A refusal is a closing session or a failed tail
+  // allocation; nothing retries the greeting, so close and let the client reconnect.
+  auto message = ws->get_config_json();
+  if (!this->try_send_nodefer(message.c_str(), message.size(), "ping", millis(), 30000)) {
+    ESP_LOGW(TAG, "Config not sent to fd %d", this->fd_.load());
+    this->request_close_();
+    return;
+  }
+
+#ifdef USE_WEBSERVER_SORTING
+  for (auto &group : ws->sorting_groups_) {
+    json::JsonBuilder builder;
+    JsonObject root = builder.root();
+    root["name"] = json::linked(group.second.name);
+    root["sorting_weight"] = group.second.weight;
+    message = builder.serialize();
+
+    // a (very) large number of these should be able to be queued initially without defer
+    // since the only thing in the send buffer at this point is the initial ping/config.
+    // A refusal means the socket is full or closing; the remaining groups are not sent. The
+    // session stays up on purpose: partial grouping beats a reconnect loop on a slow link.
+    if (!this->try_send_nodefer(message.c_str(), message.size(), "sorting_group")) {
+      ESP_LOGW(TAG, "Sorting groups not sent to fd %d", this->fd_.load());
+      break;
+    }
+  }
+#endif
+
+  this->entities_iterator_.begin(ws->include_internal_);
+}
+// NOLINTEND(clang-analyzer-cplusplus.NewDeleteLeaks)
+
+void AsyncEventSourceResponse::destroy(void *ptr) {
+  auto *rsp = static_cast<AsyncEventSourceResponse *>(ptr);
   int fd = rsp->fd_.exchange(0);  // Atomically get and clear fd
-  ESP_LOGD(TAG, "Stream connection closed (fd: %d)", fd);
-  // Mark as dead - the owner deletes it from the main loop once safe_to_delete().
+  ESP_LOGD(TAG, "Event source connection closed (fd: %d)", fd);
+  // Mark as dead - will be cleaned up in the main loop
+  // Note: We don't delete or remove from set here to avoid race conditions
   // httpd will call our custom close_fn (safe_close_with_shutdown) which handles
   // shutdown() before close() to prevent lwIP race conditions
 }
 
-void AsyncStreamResponse::close() {
+// helper for allowing only unique entries in the queue
+void AsyncEventSourceResponse::deq_push_back_with_dedup_(void *source, message_generator_t *message_generator) {
+  DeferredEvent item(source, message_generator);
+
+  // Use range-based for loop instead of std::find_if to reduce template instantiation overhead and binary size
+  for (auto &event : this->deferred_queue_) {
+    if (event == item) {
+      return;  // Already in queue, no need to update since items are equal
+    }
+  }
+  this->deferred_queue_.push_back(item);
+}
+
+void AsyncEventSourceResponse::process_deferred_queue_() {
+  if (this->close_requested_) {
+    return;
+  }
+  while (!deferred_queue_.empty()) {
+    DeferredEvent &de = deferred_queue_.front();
+    if (this->send_json_(de.source_, de.message_generator_)) {
+      if (this->close_requested_ || deferred_queue_.empty()) {
+        return;
+      }
+      // O(n) but memory efficiency is more important than speed here which is why std::vector was chosen
+      deferred_queue_.erase(deferred_queue_.begin());
+    } else {
+      break;
+    }
+  }
+}
+
+void AsyncEventSourceResponse::request_close_() {
   if (!this->close_requested_) {
     this->close_requested_ = true;
+    this->deferred_queue_.clear();
+    this->tail_.reset();
+    this->tail_cap_ = 0;
+    this->tail_len_ = 0;
+    this->tail_sent_ = 0;
     this->next_close_attempt_ms_ = App.get_loop_component_start_time();
   }
+
   this->process_close_();
 }
 
-void AsyncStreamResponse::loop() {
-  if (this->close_requested_) {
-    this->process_close_();
-  } else {
-    this->refresh_lru_();
-  }
-}
-
-void AsyncStreamResponse::process_close_() {
+void AsyncEventSourceResponse::process_close_() {
   if (!this->close_requested_ || this->close_work_queued_.load(std::memory_order_acquire)) {
     return;
   }
@@ -827,7 +971,7 @@ void AsyncStreamResponse::process_close_() {
   // httpd_sess_trigger_close() queues only a reusable fd/session slot and can
   // therefore close a new client if the original peer disconnects meanwhile.
   this->close_work_queued_.store(true, std::memory_order_release);
-  const esp_err_t err = httpd_queue_work(this->hd_, &AsyncStreamResponse::close_session_work, this);
+  const esp_err_t err = httpd_queue_work(this->hd_, &AsyncEventSourceResponse::close_session_work, this);
   this->next_close_attempt_ms_ = now + (err == ESP_OK ? CLOSE_CONFIRM_INTERVAL_MS : CLOSE_RETRY_INTERVAL_MS);
   if (err == ESP_OK) {
     return;
@@ -835,17 +979,17 @@ void AsyncStreamResponse::process_close_() {
 
   this->close_work_queued_.store(false, std::memory_order_release);
   if (!this->close_retry_warning_logged_) {
-    ESP_LOGW(TAG, "Failed to queue stream close (%s); retrying", esp_err_to_name(err));
+    ESP_LOGW(TAG, "Failed to queue EventSource close (%s); retrying", esp_err_to_name(err));
     this->close_retry_warning_logged_ = true;
   }
 }
 
-void AsyncStreamResponse::refresh_lru_() {
-  // httpd only advances a session's LRU counter when a request arrives, and a stream receives one
+void AsyncEventSourceResponse::refresh_lru_() {
+  // httpd only advances a session's LRU counter when a request arrives, and an event stream receives one
   // request ever, so the purge that frees a socket for a new client would evict the live streams first.
   // The HTTPD task owns the session table, so the refresh runs there.
   // A stalled stream is the socket the purge should take, and a zeroed fd has no session left to refresh.
-  if (this->stall_.is_running() || this->fd_.load() == 0)
+  if (this->send_failure_started_ms_ != 0 || this->fd_.load() == 0)
     return;
   const uint32_t now = App.get_loop_component_start_time();
   if (now - this->last_lru_refresh_ms_ < LRU_REFRESH_INTERVAL_MS ||
@@ -854,13 +998,13 @@ void AsyncStreamResponse::refresh_lru_() {
   }
   this->last_lru_refresh_ms_ = now;  // a full queue also waits for the next interval
   this->lru_work_queued_.store(true, std::memory_order_release);
-  if (httpd_queue_work(this->hd_, &AsyncStreamResponse::refresh_lru_work, this) != ESP_OK) {
+  if (httpd_queue_work(this->hd_, &AsyncEventSourceResponse::refresh_lru_work, this) != ESP_OK) {
     this->lru_work_queued_.store(false, std::memory_order_release);
   }
 }
 
-void AsyncStreamResponse::refresh_lru_work(void *arg) {
-  auto *response = static_cast<AsyncStreamResponse *>(arg);
+void AsyncEventSourceResponse::refresh_lru_work(void *arg) {
+  auto *response = static_cast<AsyncEventSourceResponse *>(arg);
   const int fd = response->fd_.load();
   if (response->owns_session_(fd)) {
     httpd_sess_update_lru_counter(response->hd_, fd);
@@ -869,8 +1013,8 @@ void AsyncStreamResponse::refresh_lru_work(void *arg) {
   response->lru_work_queued_.store(false, std::memory_order_release);
 }
 
-void AsyncStreamResponse::close_session_work(void *arg) {
-  auto *response = static_cast<AsyncStreamResponse *>(arg);
+void AsyncEventSourceResponse::close_session_work(void *arg) {
+  auto *response = static_cast<AsyncEventSourceResponse *>(arg);
   const int fd = response->fd_.load();
   if (response->owns_session_(fd)) {
     // The HTTPD task remains the session owner. Shutting the socket down makes
@@ -882,61 +1026,320 @@ void AsyncStreamResponse::close_session_work(void *arg) {
   response->close_work_queued_.store(false, std::memory_order_release);
 }
 
-ssize_t AsyncStreamResponse::write(struct iovec *iov, int iovcnt) {
-  if (this->close_requested_) {
-    return -1;
-  }
-  // Nothing to send is not a stall
-  size_t total = 0;
-  for (int i = 0; i < iovcnt; i++) {
-    total += iov[i].iov_len;
-  }
-  if (total == 0) {
-    return 0;
-  }
-  // httpd closes the socket before it clears the session, so the fd number may already be a new client's.
+ssize_t AsyncEventSourceResponse::send_(struct iovec *iov, int iovcnt) {
+  // httpd frees a session before closing its socket, so the fd may already be a new client's.
   // Treated as would-block; the stall timer ends a session that never becomes ours again.
   const int fd = this->fd_.load();
-  ssize_t sent = 0;
-  int err = 0;
-  {
-    // Held across the check and the send, so socket_closing() cannot close the socket in between
-    LockGuard guard{stream_send_mutex};
-    if (!this->socket_closed_ && this->owns_session_(fd)) {
-      struct msghdr msg{};
-      msg.msg_iov = iov;
-      msg.msg_iovlen = iovcnt;
-      sent = sendmsg(fd, &msg, MSG_DONTWAIT);
-      err = errno;
-    }
+  if (!this->owns_session_(fd)) {
+    return 0;
   }
-  if (sent > 0) {
-    this->stall_.clear();
+  struct msghdr msg{};
+  msg.msg_iov = iov;
+  msg.msg_iovlen = iovcnt;
+  const ssize_t sent = sendmsg(fd, &msg, MSG_DONTWAIT);
+  if (sent >= 0) {
     return sent;
   }
-  if (sent < 0 && err != EAGAIN && err != EWOULDBLOCK) {
-    ESP_LOGD(TAG, "send error: errno %d", err);
-    // A hard error is not a timeout, so is_stalled() must not report one
-    this->stall_.clear();
-    this->close();
-    return -1;
+  const int err = errno;
+  if (err == EAGAIN || err == EWOULDBLOCK) {
+    return 0;
   }
-  // Socket buffer full, try again later; a socket that stays full past the stall timeout is closed
-  const uint32_t now = App.get_loop_component_start_time();
-  this->stall_.start(now);
-  if (this->stall_.is_expired(now, SEND_STALL_TIMEOUT_MS)) {
-    ESP_LOGW(TAG, "Closing stuck stream after %" PRIu32 " ms without send progress", this->stall_.elapsed(now));
-    this->close();
-    return -1;
-  }
-  return 0;
+  ESP_LOGD(TAG, "send error: errno %d", err);
+  this->request_close_();
+  return -1;
 }
 
-ssize_t AsyncStreamResponse::write(const void *data, size_t len) {
-  struct iovec iov = {const_cast<void *>(data), len};
-  return this->write(&iov, 1);
+void AsyncEventSourceResponse::drain_tail_() {
+  if (this->sending_ || this->close_requested_ || this->tail_len_ == 0) {
+    return;
+  }
+  SendGuard guard{*this};
+
+  const size_t remaining = this->tail_len_ - this->tail_sent_;
+  struct iovec iov = {this->tail_.get() + this->tail_sent_, remaining};
+  const ssize_t sent = this->send_(&iov, 1);
+  if (sent < 0) {
+    return;
+  }
+  if (sent == 0) {
+    // Socket buffer full, try again later
+    // NOTE: Similar logic exists in web_server/web_server.cpp in DeferredUpdateEventSource::process_deferred_queue_().
+    // The IDF path is intentionally time-based and closes through HTTPD to preserve session ownership.
+    const uint32_t now = App.get_loop_component_start_time();
+    if (this->send_failure_started_ms_ == 0) {
+      this->send_failure_started_ms_ = now != 0 ? now : 1;  // Reserve zero for no stall.
+    }
+    if (static_cast<int32_t>(now - (this->send_failure_started_ms_ + SEND_STALL_TIMEOUT_MS)) >= 0) {
+      ESP_LOGW(TAG, "Closing stuck EventSource connection after %" PRIu32 " ms without send progress",
+               now - this->send_failure_started_ms_);
+      this->request_close_();
+    }
+    return;
+  }
+
+  this->send_failure_started_ms_ = 0;
+  this->tail_sent_ += sent;
+  if (this->tail_sent_ < this->tail_len_) {
+    ESP_LOGV(TAG, "Partial send: %zd/%zu bytes (total: %u/%u)", sent, remaining, this->tail_sent_, this->tail_len_);
+    return;
+  }
+  // Fully sent; the storage stays for the next stall
+  this->tail_len_ = 0;
 }
 
+bool AsyncEventSourceResponse::reserve_tail_(size_t len) {
+  if (this->tail_cap_ >= len) {
+    return true;
+  }
+  if (len > TAIL_MAX_SIZE) {
+    return false;
+  }
+  // Nothing is pending while the tail grows, so free the old block first. PREFER_INTERNAL keeps
+  // the tail where plain new put it.
+  this->tail_.reset();
+  this->tail_ = RAMAllocator<uint8_t>(RAMAllocator<uint8_t>::PREFER_INTERNAL).make_unique_array_for_overwrite(len);
+  this->tail_cap_ = this->tail_ ? len : 0;
+  return this->tail_cap_ != 0;
+}
+
+bool AsyncEventSourceResponse::stash_chunk_(const char *prefix, size_t prefix_len, const char *message,
+                                            size_t message_len, size_t total, size_t sent) {
+  // A log event of nothing but line breaks is the largest chunk; reserve_tail_() must never
+  // refuse it for size, only for memory
+  static_assert(SSE_SEP_LEN * web_server::LOG_EVENT_MAX_LEN + PREFIX_BUF_SIZE + SSE_SUFFIX_LEN <= TAIL_MAX_SIZE,
+                "the log cut in web_server.h must keep a worst case log event inside the tail ceiling");
+  if (!this->reserve_tail_(total)) {
+    if (sent != 0) {
+      // Part of the chunk is on the wire, so the stream is broken and the client has to go
+      ESP_LOGW(TAG, "Cannot buffer a %zu byte chunk, closing", total);
+      this->request_close_();
+    } else {
+      this->tail_alloc_failed_(total);  // nothing on the wire, the caller retries on the stall clock
+    }
+    return false;
+  }
+  uint8_t *dst = this->tail_.get();
+  std::memcpy(dst, prefix, prefix_len);
+  dst += prefix_len;
+  for_each_chunk_piece(
+      message, message_len,
+      [](void *ctx, const char *piece, size_t len) {
+        auto &out = *static_cast<uint8_t **>(ctx);
+        std::memcpy(out, piece, len);
+        out += len;
+      },
+      &dst);
+  this->tail_len_ = total;
+  this->tail_sent_ = sent;
+  return true;
+}
+
+void AsyncEventSourceResponse::loop() {
+  if (this->close_requested_) {
+    this->process_close_();
+    return;
+  }
+  this->refresh_lru_();
+  drain_tail_();
+  process_deferred_queue_();
+  if (this->close_requested_)
+    return;
+  // One step per loop; refusals retry next pass
+  this->entities_iterator_.try_advance(1);
+}
+
+#if defined(__GNUC__) && !defined(__clang__) && __GNUC__ >= 14 && defined(__OPTIMIZE_SIZE__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstack-usage="  // the one frame that holds the JSON arena
+#endif
+AsyncEventSourceResponse::JsonPrepareResult AsyncEventSourceResponse::prepare_json_(void *source,
+                                                                                    message_generator_t *generator,
+                                                                                    char *buffer, size_t *size_out) {
+  // Log lines emitted while the generator runs are dropped for this session: on the large path they would fill
+  // tail_ before it is overwritten, and on the small path they would go out ahead of the event being built.
+  SendGuard guard{*this};
+  json::JsonArena<json::JSON_ARENA_SIZE> arena;
+  json::JsonBuilder builder(&arena);
+  generator(this->web_server_, source, builder);
+  *size_out = builder.serialize_to(buffer, JSON_BUF_SIZE);
+  if (*size_out < JSON_BUF_SIZE) {
+    return JsonPrepareResult::JSON_PREPARE_RESULT_BUFFER;
+  }
+
+  char prefix[PREFIX_BUF_SIZE];
+  const size_t prefix_len = build_chunk_prefix(prefix, sizeof(prefix), "state", 0, 0, true);
+
+  // Nothing reaches the wire until the complete document and its framing are owned by the caller.
+  size_t json_len = 0;
+  size_t cap = std::max<size_t>(JSON_BUF_SIZE * 2, this->tail_cap_);
+  for (;;) {
+    if (!this->reserve_tail_(cap)) {
+      *size_out = cap;
+      return JsonPrepareResult::JSON_PREPARE_RESULT_NO_MEMORY;
+    }
+    const size_t room = cap - prefix_len - SSE_SUFFIX_LEN;
+    json_len = builder.serialize_to(reinterpret_cast<char *>(this->tail_.get()) + prefix_len, room);
+    if (json_len < room) {
+      break;
+    }
+    if (cap >= TAIL_MAX_SIZE) {
+      *size_out = room;
+      return JsonPrepareResult::JSON_PREPARE_RESULT_TOO_LARGE;
+    }
+    cap = std::min<size_t>(cap * 2, TAIL_MAX_SIZE);
+  }
+
+  const size_t total = prefix_len + json_len + SSE_SUFFIX_LEN;
+  write_chunk_header(prefix, total - CHUNK_HDR_LEN - CHUNK_END_LEN);
+  uint8_t *dst = this->tail_.get();
+  std::memcpy(dst, prefix, prefix_len);
+  std::memcpy(dst + prefix_len + json_len, SSE_SUFFIX, SSE_SUFFIX_LEN);
+  this->tail_len_ = total;
+  this->tail_sent_ = 0;
+  return JsonPrepareResult::JSON_PREPARE_RESULT_TAIL;
+}
+#if defined(__GNUC__) && !defined(__clang__) && __GNUC__ >= 14 && defined(__OPTIMIZE_SIZE__)
+#pragma GCC diagnostic pop
+#endif
+
+bool AsyncEventSourceResponse::send_json_(void *source, message_generator_t *generator) {
+  if (!this->ready_to_send_()) {
+    return false;
+  }
+  char buffer[JSON_BUF_SIZE];
+  size_t size;
+  const auto result = this->prepare_json_(source, generator, buffer, &size);
+  switch (result) {
+    case JsonPrepareResult::JSON_PREPARE_RESULT_BUFFER:
+      return this->try_send_nodefer(buffer, size, "state");
+    case JsonPrepareResult::JSON_PREPARE_RESULT_TAIL:
+      this->drain_tail_();
+      return true;
+    case JsonPrepareResult::JSON_PREPARE_RESULT_NO_MEMORY: {
+      SendGuard guard{*this};
+      this->tail_alloc_failed_(size);
+      return false;
+    }
+    case JsonPrepareResult::JSON_PREPARE_RESULT_TOO_LARGE: {
+      SendGuard guard{*this};
+      ESP_LOGW(TAG, "State event does not fit %zu bytes, dropped", size);
+      this->tail_.reset();
+      this->tail_cap_ = 0;
+      this->send_failure_started_ms_ = 0;
+      return true;
+    }
+  }
+  return false;
+}
+
+void AsyncEventSourceResponse::tail_alloc_failed_(size_t cap) {
+  // Same stall clock as a socket that stops draining, so a session cannot retry forever
+  const uint32_t now = App.get_loop_component_start_time();
+  if (this->send_failure_started_ms_ == 0) {
+    this->send_failure_started_ms_ = now != 0 ? now : 1;  // Reserve zero for no stall.
+    ESP_LOGW(TAG, "No memory for a %zu byte chunk", cap);
+    return;
+  }
+  if (static_cast<int32_t>(now - (this->send_failure_started_ms_ + SEND_STALL_TIMEOUT_MS)) >= 0) {
+    ESP_LOGW(TAG, "Closing EventSource after %" PRIu32 " ms without memory", now - this->send_failure_started_ms_);
+    this->request_close_();
+  }
+}
+
+bool AsyncEventSourceResponse::ready_to_send_() {
+  if (this->sending_ || this->fd_.load() == 0 || this->close_requested_) {
+    return false;
+  }
+  drain_tail_();
+  return !this->close_requested_ && this->tail_len_ == 0;
+}
+
+bool AsyncEventSourceResponse::try_send_nodefer(const char *message, size_t message_len, const char *event, uint32_t id,
+                                                uint32_t reconnect) {
+  if (!this->ready_to_send_()) {
+    return false;
+  }
+  SendGuard guard{*this};
+
+  // Everything after the prefix goes out straight from the caller's buffer
+  char prefix[PREFIX_BUF_SIZE];
+  const size_t prefix_len = build_chunk_prefix(prefix, sizeof(prefix), event, id, reconnect, message != nullptr);
+  if (message == nullptr && prefix_len == CHUNK_HDR_LEN) {
+    return true;  // Match ESPAsyncWebServer: nothing to send
+  }
+  if (prefix_len >= PREFIX_BUF_SIZE - 1) {
+    // The appenders truncate silently, which would put a malformed event on the wire
+    ESP_LOGW(TAG, "Event name too long, dropped");
+    return true;
+  }
+
+  // Gather list: the prefix, then the data lines and their separators from the message
+  struct Gather {
+    struct iovec iov[MAX_SEND_IOV];  // left uninitialized on purpose
+    int iovcnt{1};
+    size_t total{0};
+    bool fits{true};
+  } g;
+  g.total = prefix_len;
+  for_each_chunk_piece(
+      message, message_len,
+      [](void *ctx, const char *piece, size_t len) {
+        auto &g = *static_cast<Gather *>(ctx);
+        g.total += len;
+        if (len == 0) {
+          return;
+        }
+        if (g.iovcnt == MAX_SEND_IOV) {
+          g.fits = false;
+          return;
+        }
+        g.iov[g.iovcnt++] = {const_cast<char *>(piece), len};
+      },
+      &g);
+  // The header and the terminator are not part of the chunk length
+  write_chunk_header(prefix, g.total - CHUNK_HDR_LEN - CHUNK_END_LEN);
+  g.iov[0] = {prefix, prefix_len};
+
+  // A message with more lines than the list holds skips straight to the tail
+  const ssize_t sent = g.fits ? this->send_(g.iov, g.iovcnt) : 0;
+  if (sent < 0) {
+    return false;
+  }
+  if (static_cast<size_t>(sent) == g.total) {
+    this->send_failure_started_ms_ = 0;  // progress, whichever stall clock was running
+    return true;
+  }
+  // The caller's buffers do not outlive this call, so keep the chunk and continue from loop()
+  return this->stash_chunk_(prefix, prefix_len, message, message_len, g.total, sent);
+}
+
+void AsyncEventSourceResponse::deferrable_send_state(void *source, bool detail_all,
+                                                     message_generator_t *message_generator) {
+  // Let the detail_all listing finish before bare state events, so the web UI never shows unnamed entries and
+  // initial connect sends less
+  if (!detail_all && !this->entities_iterator_.completed())
+    return;
+
+  drain_tail_();
+  process_deferred_queue_();
+
+  if (this->close_requested_) {
+    return;
+  }
+
+  if (this->tail_len_ != 0 || !deferred_queue_.empty()) {
+    // outgoing event buffer or deferred queue still not empty which means downstream tcp send buffer full, no point
+    // trying to send first
+    deq_push_back_with_dedup_(source, message_generator);
+  } else {
+    // A send error closes the session and clears the queue; nothing is queued after that
+    if (!this->send_json_(source, message_generator) && !this->close_requested_) {
+      deq_push_back_with_dedup_(source, message_generator);
+    }
+  }
+}
+#endif
+
 #ifdef USE_WEBSERVER_OTA
 esp_err_t AsyncWebServer::handle_multipart_upload_(httpd_req_t *r, const char *content_type) {
   // Parse boundary and create reader

esphome/components/web_server_idf/web_server_idf.h

@@ -15,14 +15,21 @@
 #include <utility>
 #include <vector>
 
-#include "esphome/components/web_server_base/stream_head.h"
+#ifdef USE_WEBSERVER
+#include "esphome/components/json/json_util.h"
+#include "esphome/components/web_server/list_entities.h"
+#include "sse_chunk.h"
+#endif
 
 struct iovec;  // NOLINT(readability-identifier-naming) - forward decl of lwip's gather list entry
 
-namespace esphome::web_server_idf {
-
-using web_server_base::HttpHeader;
-using web_server_base::StallClock;
+namespace esphome {
+#ifdef USE_WEBSERVER
+namespace web_server {
+class WebServer;
+};  // namespace web_server
+#endif
+namespace web_server_idf {
 
 class AsyncWebParameter {
  public:
@@ -184,7 +191,6 @@ class AsyncWebServerRequest {
   void onDisconnect(std::function<void()> fn) { this->on_disconnect_ = std::move(fn); }
 #endif
 
-  /// sess_ctx is reserved for AsyncStreamResponse: the server's close_fn treats any session context as one.
   operator httpd_req_t *() const { return this->req_; }
   optional<std::string> get_header(const char *name) const;
   /// Copy a header value into buf without heap allocation.
@@ -263,85 +269,204 @@ class AsyncWebHandler {
   virtual bool isRequestHandlerTrivial() const { return true; }
 };
 
-/// A response that keeps its connection open and is written from the main loop, such as an event stream or
-/// an audio stream. Use it directly or derive from it. Call loop() and delete the object only through the type
-/// it was created as: subclasses hide loop() instead of overriding it, and the destructor is not virtual.
-///
-/// Lifecycle:
-///  1. Httpd task, inside handleRequest(): create it and call begin(), then hand the pointer to the main loop.
-///  2. Main loop: once is_attached() is true, write() may go through. Call loop() on every pass.
-///  3. Main loop: delete it once safe_to_delete() is true. httpd owns the socket throughout.
-class AsyncStreamResponse {
- public:
-  /// Httpd task, once. Sends the status line (for example HTTPD_200), Content-Type, headers, the default headers
-  /// and body (a C string or null, sent as is), then makes this object the session context. A chunked response
-  /// passes {"Transfer-Encoding", "chunked"} as its first header and frames each chunk itself.
-  void begin(AsyncWebServerRequest *request, const char *status, const char *content_type,
-             std::span<const HttpHeader> headers, const char *body = nullptr);
+#ifdef USE_WEBSERVER
+class AsyncEventSource;
+class AsyncEventSourceResponse;
 
-  /// Main loop. Non-blocking gather write. Returns the bytes accepted, which may be fewer than offered: the caller
-  /// keeps the rest and continues from there. 0 means the socket is full or not ours yet; -1 means the stream failed
-  /// and is closing. Refused writes for SEND_STALL_TIMEOUT_MS in a row also close it.
-  ssize_t write(struct iovec *iov, int iovcnt);
-  ssize_t write(const void *data, size_t len);
-  /// Main loop. Shuts the connection down through httpd; safe to call more than once.
-  void close();
-  /// Main loop, every pass. Keeps the session fresh in httpd's LRU and retries a pending close.
-  void loop();
-  /// Httpd task, from the server's close_fn: no write() reaches the socket after this returns.
-  static void socket_closing(httpd_handle_t hd, int fd);
+using message_generator_t = void(esphome::web_server::WebServer *, void *, json::JsonBuilder &);
 
-  /// httpd holds this response as the session context; begin() has sent the whole head by then.
-  bool is_attached() const { return this->owns_session_(this->fd_.load()); }
-  /// The client is still connected; httpd has not freed the session.
-  bool is_connected() const { return this->fd_.load() != 0; }
-  bool is_closing() const { return this->close_requested_; }
-  /// The socket fd, for log lines only
-  int log_id() const { return this->fd_.load(); }
-  /// Sends are making no progress; after write() returns -1 this tells a send timeout from a send error.
-  bool is_stalled() const { return this->stall_.is_running(); }
-  /// The session is gone and no queued httpd work still references this object.
-  bool safe_to_delete() const {
-    return this->fd_.load() == 0 && !this->close_work_queued_.load(std::memory_order_acquire) &&
-           !this->lru_work_queued_.load(std::memory_order_acquire);
-  }
-
-  static constexpr uint32_t SEND_STALL_TIMEOUT_MS = 20000;
+/*
+  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 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 AsyncEventSourceResponse;
 
  protected:
+  void *source_;
+  message_generator_t *message_generator_;
+
+ public:
+  DeferredEvent(void *source, message_generator_t *message_generator)
+      : source_(source), message_generator_(message_generator) {}
+  bool operator==(const DeferredEvent &test) const {
+    return (source_ == test.source_ && message_generator_ == test.message_generator_);
+  }
+};
+static_assert(sizeof(DeferredEvent) == sizeof(void *) + sizeof(message_generator_t *),
+              "DeferredEvent should have no padding");
+
+class AsyncEventSourceResponse {
+  friend class AsyncEventSource;
+
+ public:
+  bool try_send_nodefer(const char *message, size_t message_len, const char *event = nullptr, uint32_t id = 0,
+                        uint32_t reconnect = 0);
+  // detail_all events go out while entities are still being listed; state events wait until listing is done
+  void deferrable_send_state(void *source, bool detail_all, message_generator_t *message_generator);
+  // The old event name argument would otherwise convert to true
+  void deferrable_send_state(void *source, const char *event_type, message_generator_t *message_generator) = delete;
+  void loop();
+
+ protected:
+  AsyncEventSourceResponse(const AsyncWebServerRequest *request, esphome::web_server_idf::AsyncEventSource *server,
+                           esphome::web_server::WebServer *ws);
+
+  // Main-loop only: sends initial ping/config/sorting_groups, starts entity iterator.
+  void start_session_main_loop_();
+
+  void deq_push_back_with_dedup_(void *source, message_generator_t *message_generator);
+  void process_deferred_queue_();
+  // A new chunk may go out: not re-entered from a log line, session alive, tail empty
+  bool ready_to_send_();
+  // Non-blocking gather write. Returns bytes written, 0 on would-block or a socket that is not
+  // ours, -1 after requesting the close on any other error.
+  ssize_t send_(struct iovec *iov, int iovcnt);
+  // Push what is left of the chunk in tail_ to the socket; owns the stall timer.
+  void drain_tail_();
+  // Grow tail_ to hold len bytes, kept at its high-water mark. False on OOM.
+  bool reserve_tail_(size_t len);
+  // Keep the whole chunk in tail_ and continue from sent; false when the tail cannot be allocated.
+  bool stash_chunk_(const char *prefix, size_t prefix_len, const char *message, size_t message_len, size_t total,
+                    size_t sent);
+  // Send a state event; JSON too large for the stack buffer is serialized into tail_ instead
+  bool send_json_(void *source, message_generator_t *generator);
+  enum class JsonPrepareResult : uint8_t {
+    JSON_PREPARE_RESULT_BUFFER,
+    JSON_PREPARE_RESULT_TAIL,
+    JSON_PREPARE_RESULT_NO_MEMORY,
+    JSON_PREPARE_RESULT_TOO_LARGE,
+  };
+  // Keep the arena out of the caller's frame so it is gone before the state send.
+  // size_out: BUFFER = JSON length, NO_MEMORY = requested tail capacity, TOO_LARGE = available JSON room;
+  // unused for TAIL.
+  JsonPrepareResult __attribute__((noinline)) prepare_json_(void *source, message_generator_t *generator, char *buffer,
+                                                            size_t *size_out);
+  // Warn once, and close the session once the stall timeout passes with no memory for the tail
+  void tail_alloc_failed_(size_t cap);
+  void request_close_();
+
+  // A log line emitted inside a send re-enters try_send_nodefer on this session; refuse it
+  struct SendGuard {
+    AsyncEventSourceResponse &owner;
+    explicit SendGuard(AsyncEventSourceResponse &owner) : owner(owner) { owner.sending_ = true; }
+    ~SendGuard() { this->owner.sending_ = false; }
+  };
   void process_close_();
   static void close_session_work(void *arg);
   void refresh_lru_();
   static void refresh_lru_work(void *arg);
-  // httpd closes the socket before it clears the session, so this can still match a closed fd; write() also checks
-  // socket_closed_
+  // httpd frees a session before closing its socket, so the fd may already belong to a new client
   bool owns_session_(int fd) const { return fd != 0 && httpd_sess_get_ctx(this->hd_, fd) == this; }
-  static void destroy(void *p);
 
+  // Deletable only after destroy() zeroed fd_ and no queued HTTPD work still references this object.
+  bool safe_to_delete_() const {
+    return this->fd_.load() == 0 && !this->close_work_queued_.load(std::memory_order_acquire) &&
+           !this->lru_work_queued_.load(std::memory_order_acquire);
+  }
+
+  static void destroy(void *p);
+  AsyncEventSource *server_;
   httpd_handle_t hd_{};
   std::atomic<int> fd_{};
-  // Runs while sends make no progress; a running clock keeps its start time
-  StallClock stall_;
+  std::vector<DeferredEvent> deferred_queue_;
+  esphome::web_server::WebServer *web_server_;
+  esphome::web_server::ListEntitiesIterator entities_iterator_;
+  // One chunk the socket did not take whole, allocated on the first stall; the only heap use
+  // on the send path
+  RAMUniquePtr<uint8_t[]> tail_;
+  uint32_t send_failure_started_ms_{0};  // Zero means no send stall in progress.
   uint32_t next_close_attempt_ms_{0};
   uint32_t last_lru_refresh_ms_{0};
+  uint16_t tail_cap_{0};
+  uint16_t tail_len_{0};  // Zero means nothing pending
+  uint16_t tail_sent_{0};
   // Set on the main loop before queueing close work, cleared by the HTTPD-task callback when done.
   std::atomic<bool> close_work_queued_{false};
   std::atomic<bool> lru_work_queued_{false};
-  // Guarded by the stream send mutex
-  bool socket_closed_{false};
   // Main-loop only; the HTTPD task never reads or writes these flags.
   bool close_requested_{false};
   bool close_retry_warning_logged_{false};
+  bool sending_{false};
+  // The longest multi line log message in the tree (a climate dump_config) has 22 lines; a
+  // longer one goes through the tail
+  static constexpr size_t MAX_SEND_LINES = 22;
+  static constexpr size_t MAX_SEND_IOV = 1 + 2 * MAX_SEND_LINES;
+  // Chunk header, retry/id/event lines and the first "data: "
+  static constexpr size_t PREFIX_BUF_SIZE = 128;
 
+  // Stack buffer for a state event's JSON; a larger document is serialized into the tail
+  static constexpr size_t JSON_BUF_SIZE = 1024;
+  // Same ceiling JsonBuilder::serialize() applies (max_heap_size in json_util.cpp); a larger
+  // document is dropped before anything is on the wire
+  static constexpr size_t JSON_MAX_SIZE = 5120;
+  // Most RAM a stalled session keeps: the largest state document plus any accepted framing
+  static constexpr size_t TAIL_MAX_SIZE = JSON_MAX_SIZE + PREFIX_BUF_SIZE + SSE_SUFFIX_LEN;
+  static constexpr uint32_t SEND_STALL_TIMEOUT_MS = 20000;
   static constexpr uint32_t CLOSE_RETRY_INTERVAL_MS = 250;
   static constexpr uint32_t CLOSE_CONFIRM_INTERVAL_MS = 1000;
   static constexpr uint32_t LRU_REFRESH_INTERVAL_MS = 1000;
 };
 
+using AsyncEventSourceClient = AsyncEventSourceResponse;
+
+class AsyncEventSource : public AsyncWebHandler {
+  friend class AsyncEventSourceResponse;
+
+ public:
+  AsyncEventSource(StringRef url, esphome::web_server::WebServer *ws) : url_(url), web_server_(ws) {}
+  ~AsyncEventSource() override;
+
+  // NOLINTNEXTLINE(readability-identifier-naming)
+  bool canHandle(AsyncWebServerRequest *request) const override {
+    if (request->method() != HTTP_GET)
+      return false;
+    char url_buf[AsyncWebServerRequest::URL_BUF_SIZE];
+    return request->url_to(url_buf) == this->url_;
+  }
+  // NOLINTNEXTLINE(readability-identifier-naming)
+  void handleRequest(AsyncWebServerRequest *request) override;
+  void try_send_nodefer(const char *message, size_t message_len, const char *event = nullptr, uint32_t id = 0,
+                        uint32_t reconnect = 0);
+  void deferrable_send_state(void *source, bool detail_all, message_generator_t *message_generator);
+  // The old event name argument would otherwise convert to true
+  void deferrable_send_state(void *source, const char *event_type, message_generator_t *message_generator) = delete;
+  /// Returns true if there are sessions remaining (including pending cleanup).
+  bool loop();
+  bool empty() { return this->count() == 0; }
+
+  size_t count() const { return this->sessions_.size(); }
+
+ protected:
+  // Cold path: move sessions from pending_sessions_ into sessions_ and greet each one.
+  void __attribute__((noinline, cold)) adopt_pending_sessions_main_loop_();
+
+  StringRef url_;  // Must outlive this object (string literal)
+  // Main-loop only. Vector: SSE sessions are 1-5 connections, linear search beats set.
+  std::vector<AsyncEventSourceResponse *> sessions_;
+  // Httpd-task intake; guarded by pending_mutex_, gated by has_pending_sessions_.
+  std::vector<AsyncEventSourceResponse *> pending_sessions_;
+  Mutex pending_mutex_;
+  esphome::web_server::WebServer *web_server_;
+  std::atomic<bool> has_pending_sessions_{false};
+};
+#endif  // USE_WEBSERVER
+
+struct HttpHeader {
+  const char *name;
+  const char *value;
+};
+
 class DefaultHeaders {
   friend class AsyncWebServerRequest;
-  friend class AsyncStreamResponse;
   friend class AsyncWebServerResponse;
+#ifdef USE_WEBSERVER
+  friend class AsyncEventSourceResponse;
+#endif
   static_assert(WEB_SERVER_DEFAULT_HEADERS_COUNT <= 8, "AsyncWebServerResponse::replaced_defaults_ holds 8 bits");
 
  public:
@@ -359,7 +484,8 @@ class DefaultHeaders {
   void apply_(httpd_req_t *req, uint8_t skip_mask = 0) const;
 };
 
-}  // namespace esphome::web_server_idf
+}  // namespace web_server_idf
+}  // namespace esphome
 
 using namespace esphome::web_server_idf;  // NOLINT(google-global-names-in-headers)
 

esphome/core/defines.h

@@ -151,6 +151,7 @@
 #define USE_LINE_READER
 #define USE_LOCK
 #define USE_LOGGER
+#define USE_LOGGER_CONSOLE
 #define USE_LOGGER_LEVEL_LISTENERS
 #define USE_LOGGER_RUNTIME_TAG_LEVELS
 #define USE_LVGL
@@ -758,16 +759,26 @@
 #if defined(USE_ESP32_VARIANT_ESP32S2)
 #define USE_LOGGER_USB_CDC
 #define USE_LOGGER_UART_SELECTION_USB_CDC
+#define ESPHOME_LOGGER_UART_NAME "USB_CDC"
+#define ESPHOME_LOGGER_UART_SELECTION logger::UART_SELECTION_USB_CDC
 #elif defined(USE_ESP32_VARIANT_ESP32H21)
 #define USE_LOGGER_USB_SERIAL_JTAG
+#define USE_LOGGER_UART_SELECTION_USB_SERIAL_JTAG
+#define ESPHOME_LOGGER_UART_NAME "USB_SERIAL_JTAG"
+#define ESPHOME_LOGGER_UART_SELECTION logger::UART_SELECTION_USB_SERIAL_JTAG
 #elif defined(USE_ESP32_VARIANT_ESP32C3) || defined(USE_ESP32_VARIANT_ESP32C5) || \
     defined(USE_ESP32_VARIANT_ESP32C6) || defined(USE_ESP32_VARIANT_ESP32C61) || defined(USE_ESP32_VARIANT_ESP32H2) || \
-    defined(USE_ESP32_VARIANT_ESP32H21) || defined(USE_ESP32_VARIANT_ESP32H4) || defined(USE_ESP32_VARIANT_ESP32P4) || \
-    defined(USE_ESP32_VARIANT_ESP32S3) || defined(USE_ESP32_VARIANT_ESP32S31)
+    defined(USE_ESP32_VARIANT_ESP32H4) || defined(USE_ESP32_VARIANT_ESP32P4) || defined(USE_ESP32_VARIANT_ESP32S3) || \
+    defined(USE_ESP32_VARIANT_ESP32S31)
 #define USE_LOGGER_USB_CDC
-#define USE_LOGGER_UART_SELECTION_USB_CDC
 #define USE_LOGGER_USB_SERIAL_JTAG
 #define USE_LOGGER_UART_SELECTION_USB_SERIAL_JTAG
+#define ESPHOME_LOGGER_UART_NAME "USB_SERIAL_JTAG"
+#define ESPHOME_LOGGER_UART_SELECTION logger::UART_SELECTION_USB_SERIAL_JTAG
+#else
+#define USE_LOGGER_UART_SELECTION_UART0
+#define ESPHOME_LOGGER_UART_NAME "UART0"
+#define ESPHOME_LOGGER_UART_SELECTION logger::UART_SELECTION_UART0
 #endif
 #endif
 
@@ -781,6 +792,9 @@
 #define USE_WIFI_SCAN_RESULTS_LOCK
 #define USE_ESP8266_LOGGER_SERIAL
 #define USE_ESP8266_LOGGER_SERIAL1
+#define USE_LOGGER_UART_SELECTION_UART0
+#define ESPHOME_LOGGER_UART_NAME "UART0"
+#define ESPHOME_LOGGER_UART_SELECTION logger::UART_SELECTION_UART0
 #define USE_ESP8266_PREFERENCES_FLASH
 #define ESP8266_PREFERENCES_FLASH_WORDS 128
 #define ESP8266_PREFERENCES_RTC_EBOOT_WORDS 32
@@ -826,6 +840,8 @@
 #define USE_I2C
 #define USE_LOGGER_USB_CDC
 #define USE_LOGGER_UART_SELECTION_USB_CDC
+#define ESPHOME_LOGGER_UART_NAME "USB_CDC"
+#define ESPHOME_LOGGER_UART_SELECTION logger::UART_SELECTION_USB_CDC
 #define USE_SOCKET_IMPL_LWIP_TCP
 #define USE_RP2040_BLE
 #define USE_RP2_BLE_TRACKER
@@ -856,6 +872,9 @@
 #if defined(USE_BK72XX) || defined(USE_RTL87XX) || defined(USE_LN882X)
 #define USE_LIBRETINY_CRASH_HANDLER
 #endif
+#define USE_LOGGER_UART_SELECTION_DEFAULT
+#define ESPHOME_LOGGER_UART_NAME "DEFAULT"
+#define ESPHOME_LOGGER_UART_SELECTION logger::UART_SELECTION_DEFAULT
 #ifdef USE_BK72XX
 #define USE_REMOTE_RECEIVER_TIMER_SAMPLING
 #endif
@@ -910,8 +929,11 @@
 #define ESPHOME_TASK_LOG_BUFFER_SIZE 768
 #define USE_LOGGER_EARLY_MESSAGE
 #define USE_LOGGER_UART_SELECTION_USB_CDC
+#define ESPHOME_LOGGER_UART_NAME "USB_CDC"
+#define ESPHOME_LOGGER_UART_SELECTION logger::UART_SELECTION_USB_CDC
 #define USE_LOGGER_USB_CDC
 #define USE_LOGGER_WAIT_FOR_CDC
+#define USE_LOGGER_ZEPHYR_CDC_LOOP
 #define USE_NRF52_DFU
 #define USE_NRF52_REG0_VOUT 5
 #define USE_NRF52_UICR_ERASE

tests/component_tests/logger/test_logger.py

@@ -68,38 +68,6 @@ def test_logger_pre_setup_before_other_components(generate_main):
         )
 
 
-def test_default_uart_selection_is_not_emitted(generate_main):
-    """UART0 is the C++ initializer on ESP8266, so the setter is skipped."""
-    main_cpp = generate_main("tests/component_tests/logger/test_logger.yaml")
-
-    assert "set_uart_selection(" not in main_cpp
-
-
-def test_custom_uart_selection_is_emitted(generate_main):
-    """A non default UART still reaches the setter before pre_setup()."""
-    main_cpp = generate_main("tests/component_tests/logger/test_logger_uart1.yaml")
-
-    assert "set_uart_selection(logger::UART_SELECTION_UART1);" in main_cpp
-
-
-def test_libretiny_default_uart_selection_is_not_emitted(generate_main):
-    """DEFAULT is the C++ initializer on LibreTiny, so the setter is skipped."""
-    main_cpp = generate_main(
-        "tests/component_tests/logger/test_logger_libretiny_default.yaml"
-    )
-
-    assert "set_uart_selection(" not in main_cpp
-
-
-def test_libretiny_uart0_is_emitted(generate_main):
-    """UART0 is not the LibreTiny initializer, so it must still be set."""
-    main_cpp = generate_main(
-        "tests/component_tests/logger/test_logger_libretiny_uart0.yaml"
-    )
-
-    assert "set_uart_selection(logger::UART_SELECTION_UART0);" in main_cpp
-
-
 def test_ram_log_strings_is_deprecated(
     generate_main: Callable[[str | Path], str],
     caplog: pytest.LogCaptureFixture,
@@ -168,23 +136,108 @@ def test_log_v2_only_on_native_toolchain(
 
 
 @pytest.mark.parametrize(
-    ("config", "usb_cdc"),
+    ("config", "port", "name", "zephyr_cdc_loop"),
     [
-        pytest.param("test_logger_rp2_usb_cdc.yaml", True, id="usb_cdc"),
-        pytest.param("test_logger_rp2_uart0.yaml", False, id="uart0"),
+        pytest.param("test_logger.yaml", "UART0", "UART0", False, id="esp8266_default"),
+        pytest.param(
+            "test_logger_uart1.yaml", "UART1", "UART1", False, id="esp8266_uart1"
+        ),
+        pytest.param(
+            "test_logger_uart0_swap.yaml",
+            "UART0_SWAP",
+            "UART0_SWAP",
+            False,
+            id="esp8266_uart0_swap",
+        ),
+        # ESP8266 without serial logging never opens a port
+        pytest.param(
+            "test_logger_no_serial.yaml", "UART0", "NONE", False, id="esp8266_no_serial"
+        ),
+        pytest.param(
+            "test_logger_libretiny_default.yaml",
+            "DEFAULT",
+            "DEFAULT",
+            False,
+            id="libretiny_default",
+        ),
+        pytest.param(
+            "test_logger_libretiny_uart0.yaml",
+            "UART0",
+            "UART0",
+            False,
+            id="libretiny_uart0",
+        ),
+        pytest.param(
+            "test_logger_rp2_usb_cdc.yaml",
+            "USB_CDC",
+            "USB_CDC",
+            False,
+            id="rp2_usb_cdc",
+        ),
+        pytest.param(
+            "test_logger_rp2_uart0.yaml", "UART0", "UART0", False, id="rp2_uart0"
+        ),
+        pytest.param(
+            "test_logger_esp32_usb_cdc.yaml",
+            "USB_CDC",
+            "USB_CDC",
+            False,
+            id="esp32_usb_cdc",
+        ),
+        pytest.param(
+            "test_logger_esp32_usb_serial_jtag.yaml",
+            "USB_SERIAL_JTAG",
+            "USB_SERIAL_JTAG",
+            False,
+            id="esp32_usb_serial_jtag",
+        ),
+        pytest.param(
+            "test_logger_nrf52_usb_cdc.yaml",
+            "USB_CDC",
+            "USB_CDC",
+            True,
+            id="nrf52_usb_cdc",
+        ),
+        # Zephyr polls the USB port only when it logs there
+        pytest.param(
+            "test_logger_nrf52_usb_cdc_no_serial.yaml",
+            "USB_CDC",
+            "USB_CDC",
+            False,
+            id="nrf52_no_serial",
+        ),
     ],
 )
-def test_rp2_usb_cdc_selection_define(
+def test_uart_selection_defines(
     generate_main: Callable[[str | Path], str],
     config: str,
-    usb_cdc: bool,
+    port: str,
+    name: str,
+    zephyr_cdc_loop: bool,
 ) -> None:
-    """The USB CDC crash replay only compiles in when the logger uses USB CDC."""
+    """The chosen port is fixed at build time: one flag, its enum value and its dump_config name."""
     generate_main(f"tests/component_tests/logger/{config}")
 
+    defines = {d.name: d.value for d in CORE.defines}
+    prefix = "USE_LOGGER_UART_SELECTION_"
+    assert {d.removeprefix(prefix) for d in defines if d.startswith(prefix)} == {port}
     assert (
-        "USE_LOGGER_UART_SELECTION_USB_CDC" in {d.name for d in CORE.defines}
-    ) is usb_cdc
+        str(defines["ESPHOME_LOGGER_UART_SELECTION"])
+        == f"logger::UART_SELECTION_{port}"
+    )
+    assert str(defines["ESPHOME_LOGGER_UART_NAME"]) == f'"{name}"'
+    assert ("USE_LOGGER_ZEPHYR_CDC_LOOP" in defines) is zephyr_cdc_loop
+
+
+def test_log_listener_slots_count_every_listener(
+    generate_main: Callable[[str | Path], str],
+) -> None:
+    """Two on_message triggers and the API each take a slot."""
+    generate_main("tests/component_tests/logger/test_logger_listeners.yaml")
+
+    assert (
+        str({d.name: d.value for d in CORE.defines}["ESPHOME_LOG_MAX_LISTENERS"]) == "3"
+    )
 
 
 @pytest.mark.parametrize(

tests/component_tests/logger/test_logger_esp32_usb_cdc.yaml

@@ -0,0 +1,11 @@
+---
+esphome:
+  name: test
+
+esp32:
+  variant: esp32s3
+  framework:
+    type: esp-idf
+
+logger:
+  hardware_uart: USB_CDC

tests/component_tests/logger/test_logger_esp32_usb_serial_jtag.yaml

@@ -0,0 +1,11 @@
+---
+esphome:
+  name: test
+
+esp32:
+  variant: esp32c3
+  framework:
+    type: esp-idf
+
+logger:
+  hardware_uart: USB_SERIAL_JTAG

tests/component_tests/logger/test_logger_listeners.yaml

@@ -0,0 +1,23 @@
+---
+esphome:
+  name: test
+
+esp32:
+  variant: esp32
+  framework:
+    type: esp-idf
+
+wifi:
+  ssid: test
+  password: testtesttest
+
+api:
+
+logger:
+  on_message:
+    - level: ERROR
+      then:
+        - lambda: "(void) message;"
+    - level: WARN
+      then:
+        - lambda: "(void) message;"

tests/component_tests/logger/test_logger_no_serial.yaml

@@ -0,0 +1,9 @@
+---
+esphome:
+  name: test
+
+esp8266:
+  board: d1_mini_lite
+
+logger:
+  baud_rate: 0

tests/component_tests/logger/test_logger_nrf52_usb_cdc.yaml

@@ -0,0 +1,10 @@
+---
+esphome:
+  name: test
+
+nrf52:
+  board: adafruit_itsybitsy_nrf52840
+  bootloader: adafruit_nrf52_sd140_v6
+
+logger:
+  hardware_uart: USB_CDC

tests/component_tests/logger/test_logger_nrf52_usb_cdc_no_serial.yaml

@@ -0,0 +1,11 @@
+---
+esphome:
+  name: test
+
+nrf52:
+  board: adafruit_itsybitsy_nrf52840
+  bootloader: adafruit_nrf52_sd140_v6
+
+logger:
+  hardware_uart: USB_CDC
+  baud_rate: 0

tests/component_tests/logger/test_logger_uart0_swap.yaml

@@ -0,0 +1,9 @@
+---
+esphome:
+  name: test
+
+esp8266:
+  board: d1_mini_lite
+
+logger:
+  hardware_uart: UART0_SWAP

tests/components/logger/task_log_message_test.cpp

@@ -0,0 +1,54 @@
+#include <gtest/gtest.h>
+#include <cstring>
+
+#include "esphome/core/defines.h"
+
+// The cap and message header are compiled only for platforms with a task log buffer
+#define USE_LIBRETINY
+#ifndef USE_ESPHOME_TASK_LOG_BUFFER
+#define USE_ESPHOME_TASK_LOG_BUFFER
+#endif
+#include "esphome/components/logger/task_log_message.h"
+#undef USE_LIBRETINY
+
+namespace esphome::logger::testing {
+
+TEST(TaskLogMessageTest, CapLengthStopsAt255) {
+  EXPECT_EQ(task_log_cap_length(0), 0);
+  EXPECT_EQ(task_log_cap_length(255), 255);
+  EXPECT_EQ(task_log_cap_length(256), 255);
+  EXPECT_EQ(task_log_cap_length(1000), 255);
+}
+
+TEST(TaskLogMessageTest, HeaderCopiesFieldsAndThreadName) {
+  TaskLogMessage msg{};
+  fill_task_log_header(&msg, 3, "tag", 42, "worker");
+  EXPECT_EQ(msg.level, 3);
+  EXPECT_STREQ(msg.tag, "tag");
+  EXPECT_EQ(msg.line, 42);
+  EXPECT_STREQ(msg.thread_name, "worker");
+}
+
+TEST(TaskLogMessageTest, HeaderNullThreadNameIsEmpty) {
+  TaskLogMessage msg{};
+  std::memset(msg.thread_name, 'x', sizeof(msg.thread_name));
+  fill_task_log_header(&msg, 1, "tag", 1, nullptr);
+  EXPECT_STREQ(msg.thread_name, "");
+}
+
+TEST(TaskLogMessageTest, HeaderTruncatesLongThreadName) {
+  TaskLogMessage msg{};
+  fill_task_log_header(&msg, 1, "tag", 1, "a_thread_name_longer_than_sixteen");
+  EXPECT_EQ(std::strlen(msg.thread_name), sizeof(msg.thread_name) - 1);
+  EXPECT_EQ(std::strncmp(msg.thread_name, "a_thread_name_l", sizeof(msg.thread_name) - 1), 0);
+}
+
+TEST(TaskLogMessageTest, TrimTrailingNewlines) {
+  EXPECT_EQ(trim_trailing_newlines("", 0), 0);
+  EXPECT_EQ(trim_trailing_newlines("abc", 3), 3);
+  EXPECT_EQ(trim_trailing_newlines("abc\n\n", 5), 3);
+  EXPECT_EQ(trim_trailing_newlines("\n\n\n", 3), 0);
+  EXPECT_EQ(trim_trailing_newlines("a\nb", 3), 3);
+}
+
+}  // namespace esphome::logger::testing

tests/components/web_server/test_stream_head.cpp

@@ -1,300 +0,0 @@
-#ifdef USE_HOST
-#include <gtest/gtest.h>
-
-#include <sys/uio.h>
-
-#include <cstdint>
-#include <cstdio>
-#include <string>
-#include <vector>
-
-#include "esphome/components/web_server/sse_chunk.h"
-#include "esphome/components/web_server_base/stream_head.h"
-
-namespace esphome::web_server::testing {
-
-using namespace web_server_base;  // NOLINT(google-build-using-namespace)
-
-// Collects every batch write_stream_head() sends
-struct Capture {
-  std::string bytes;
-  std::vector<int> batch_sizes;
-  int attempts{0};
-  int fail_after_batches{-1};
-
-  bool operator()(struct iovec *iov, int count) {
-    this->attempts++;
-    if (static_cast<int>(this->batch_sizes.size()) == this->fail_after_batches) {
-      return false;
-    }
-    this->batch_sizes.push_back(count);
-    for (int i = 0; i < count; i++) {
-      this->bytes.append(static_cast<const char *>(iov[i].iov_base), iov[i].iov_len);
-    }
-    return true;
-  }
-};
-
-static std::string build_head(Capture &cap, const char *status, const char *content_type,
-                              std::span<const HttpHeader> headers, std::span<const HttpHeader> defaults,
-                              const char *body) {
-  EXPECT_TRUE(write_stream_head<struct iovec>(cap, status, content_type, headers, defaults, body));
-  return cap.bytes;
-}
-
-// What httpd_resp_send_chunk() put on the wire for its first chunk (esp_http_server/src/httpd_txrx.c in
-// ESP-IDF 5.5): the chunked head with Transfer-Encoding, each httpd_resp_set_hdr() header, the blank line,
-// then "%lx\r\n", the chunk data and "\r\n".
-static std::string reference_send_chunk(const char *status, const char *content_type,
-                                        const std::vector<HttpHeader> &resp_hdrs, const char *buf, size_t buf_len) {
-  char head[256];
-  std::string out(
-      head, snprintf(head, sizeof(head), "HTTP/1.1 %s\r\nContent-Type: %s\r\nTransfer-Encoding: chunked\r\n", status,
-                     content_type));
-  for (const auto &hdr : resp_hdrs) {
-    out.append(hdr.name).append(": ").append(hdr.value).append("\r\n");
-  }
-  out.append("\r\n");
-  char len_str[10];
-  out.append(len_str, snprintf(len_str, sizeof(len_str), "%lx\r\n", static_cast<long>(buf_len)));
-  out.append(buf, buf_len);
-  out.append("\r\n");
-  return out;
-}
-
-static constexpr HttpHeader DEFAULTS[] = {
-    {"Access-Control-Allow-Origin", "*"},
-    {"Access-Control-Allow-Private-Network", "true"},
-};
-
-TEST(StreamHead, SseHeadMatchesHttpdRespSendChunk) {
-  // The old event source set Cache-Control and Connection, then the default headers, and sent "\r\n" as a chunk
-  const std::string expected = reference_send_chunk(
-      "200 OK", "text/event-stream",
-      {{"Cache-Control", "no-cache"}, {"Connection", "keep-alive"}, DEFAULTS[0], DEFAULTS[1]}, "\r\n", 2);
-  Capture cap;
-  EXPECT_EQ(build_head(cap, SSE_STATUS, SSE_CONTENT_TYPE, SSE_HEADERS, DEFAULTS, SSE_FIRST_CHUNK), expected);
-}
-
-TEST(StreamHead, HeaderReplacesDefaultOfSameName) {
-  // A default the caller also sets, in any case, goes out once with the caller's value
-  static constexpr HttpHeader HEADERS[] = {
-      {"access-control-allow-origin", "http://example.com"},
-  };
-  Capture cap;
-  EXPECT_EQ(build_head(cap, "200 OK", "text/plain", HEADERS, DEFAULTS, nullptr),
-            "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\naccess-control-allow-origin: http://example.com"
-            "\r\nAccess-Control-Allow-Private-Network: true\r\n\r\n");
-}
-
-TEST(StreamHead, RawHeadWithCustomHeadersAndNoBody) {
-  static constexpr HttpHeader HEADERS[] = {
-      {"Cache-Control", "no-store"},
-      {"X-Stream", "audio"},
-  };
-  Capture cap;
-  EXPECT_EQ(build_head(cap, "200 OK", "audio/wav", HEADERS, {}, nullptr), "HTTP/1.1 200 OK\r\n"
-                                                                          "Content-Type: audio/wav\r\n"
-                                                                          "Cache-Control: no-store\r\n"
-                                                                          "X-Stream: audio\r\n"
-                                                                          "\r\n");
-}
-
-TEST(StreamHead, BareHead) {
-  Capture cap;
-  EXPECT_EQ(build_head(cap, "204 No Content", "text/plain", {}, {}, nullptr),
-            "HTTP/1.1 204 No Content\r\nContent-Type: text/plain\r\n\r\n");
-  EXPECT_EQ(cap.batch_sizes, std::vector<int>{5});
-}
-
-TEST(StreamHead, ManyHeadersSplitIntoBatchesWithSameBytes) {
-  // 4 + 12 * 4 + 2 = 54 pieces, more than two batches hold
-  static constexpr HttpHeader HEADERS[] = {
-      {"X-Header-0", "value-0"}, {"X-Header-1", "value-1"}, {"X-Header-2", "value-2"}, {"X-Header-3", "value-3"},
-      {"X-Header-4", "value-4"}, {"X-Header-5", "value-5"}, {"X-Header-6", "value-6"}, {"X-Header-7", "value-7"},
-      {"X-Header-8", "value-8"}, {"X-Header-9", "value-9"},
-  };
-  const std::span<const HttpHeader> headers{HEADERS};
-
-  Capture batched;
-  const std::string bytes = build_head(batched, "200 OK", "text/plain", headers, DEFAULTS, "body");
-  EXPECT_EQ(batched.batch_sizes, (std::vector<int>{STREAM_HEAD_MAX_IOV, STREAM_HEAD_MAX_IOV, 6}));
-
-  std::string expected = "HTTP/1.1 200 OK\r\nContent-Type: text/plain";
-  const auto append_headers = [&expected](std::span<const HttpHeader> list) {
-    for (const auto &h : list) {
-      expected.append("\r\n").append(h.name).append(": ").append(h.value);
-    }
-  };
-  append_headers(headers);
-  append_headers(DEFAULTS);
-  expected.append("\r\n\r\nbody");
-  EXPECT_EQ(bytes, expected);
-}
-
-TEST(StreamHead, BatchBoundary) {
-  // 4 + 4 * 4 + 1 + 1 = 22 pieces fit one batch; a fifth header makes 4 + 5 * 4 = 24 before the blank line
-  static constexpr HttpHeader HEADERS[] = {{"A", "1"}, {"B", "2"}, {"C", "3"}, {"D", "4"}, {"E", "5"}};
-  Capture four;
-  build_head(four, "200 OK", "text/plain", std::span(HEADERS, 4), {}, "x");
-  EXPECT_EQ(four.batch_sizes, std::vector<int>{22});
-  EXPECT_EQ(stream_head_iov_count(4), 22u);
-  Capture five;
-  const std::string bytes = build_head(five, "200 OK", "text/plain", HEADERS, {}, "x");
-  EXPECT_EQ(five.batch_sizes, (std::vector<int>{STREAM_HEAD_MAX_IOV, 2}));
-  EXPECT_EQ(bytes, "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\nA: 1\r\nB: 2\r\nC: 3\r\nD: 4\r\nE: 5\r\n\r\nx");
-}
-
-TEST(StreamHead, FailedSendSkipsLaterBatches) {
-  // Three batches; the second fails, so the third is never sent
-  std::vector<HttpHeader> headers(12, HttpHeader{"X", "y"});
-  Capture full;
-  build_head(full, "200 OK", "text/plain", headers, {}, nullptr);
-  ASSERT_EQ(full.batch_sizes.size(), 3u);
-  Capture cap;
-  cap.fail_after_batches = 1;
-  EXPECT_FALSE(write_stream_head<struct iovec>(cap, "200 OK", "text/plain", headers, {}, nullptr));
-  EXPECT_EQ(cap.attempts, 2);
-  EXPECT_EQ(cap.batch_sizes.size(), 1u);
-}
-
-// Three elements of 3, 4 and 5 bytes
-struct IovFixture {
-  char a[4] = "abc";
-  char b[5] = "defg";
-  char c[6] = "hijkl";
-  struct iovec iov[3] = {{a, 3}, {b, 4}, {c, 5}};
-  struct iovec *cur = iov;
-  int count = 3;
-
-  std::string rest() const {
-    std::string out;
-    for (int i = 0; i < this->count; i++) {
-      out.append(static_cast<const char *>(this->cur[i].iov_base), this->cur[i].iov_len);
-    }
-    return out;
-  }
-};
-
-TEST(AdvanceIovecs, ZeroLengthWriteChangesNothing) {
-  IovFixture f;
-  advance_iovecs(f.cur, f.count, 0);
-  EXPECT_EQ(f.cur, f.iov);
-  EXPECT_EQ(f.count, 3);
-  EXPECT_EQ(f.rest(), "abcdefghijkl");
-}
-
-TEST(AdvanceIovecs, PartialInsideFirstElement) {
-  IovFixture f;
-  advance_iovecs(f.cur, f.count, 2);
-  EXPECT_EQ(f.cur, f.iov);
-  EXPECT_EQ(f.count, 3);
-  EXPECT_EQ(f.cur->iov_len, 1u);
-  EXPECT_EQ(f.rest(), "cdefghijkl");
-}
-
-TEST(AdvanceIovecs, ExactlyOnElementBoundary) {
-  IovFixture f;
-  advance_iovecs(f.cur, f.count, 3);
-  EXPECT_EQ(f.cur, &f.iov[1]);
-  EXPECT_EQ(f.count, 2);
-  EXPECT_EQ(f.rest(), "defghijkl");
-}
-
-TEST(AdvanceIovecs, AcrossElementBoundaries) {
-  IovFixture f;
-  advance_iovecs(f.cur, f.count, 9);
-  EXPECT_EQ(f.cur, &f.iov[2]);
-  EXPECT_EQ(f.count, 1);
-  EXPECT_EQ(f.rest(), "jkl");
-}
-
-TEST(AdvanceIovecs, RepeatedShortWrites) {
-  IovFixture f;
-  std::string sent;
-  while (f.count > 0) {
-    const std::string before = f.rest();
-    advance_iovecs(f.cur, f.count, 2);
-    sent += before.substr(0, before.size() - f.rest().size());
-  }
-  EXPECT_EQ(sent, "abcdefghijkl");
-}
-
-TEST(AdvanceIovecs, EverythingWritten) {
-  IovFixture f;
-  advance_iovecs(f.cur, f.count, 12);
-  EXPECT_EQ(f.count, 0);
-  EXPECT_EQ(f.rest(), "");
-}
-
-TEST(AdvanceIovecs, SkipsZeroLengthElements) {
-  char a[] = "ab";
-  char c[] = "cd";
-  struct iovec iov[3] = {{a, 2}, {nullptr, 0}, {c, 2}};
-  struct iovec *cur = iov;
-  int count = 3;
-  advance_iovecs(cur, count, 2);
-  EXPECT_EQ(cur, &iov[2]);
-  EXPECT_EQ(count, 1);
-}
-
-static constexpr uint32_t TIMEOUT = 20000;
-
-TEST(StallClock, NotStarted) {
-  StallClock clock;
-  EXPECT_FALSE(clock.is_running());
-  EXPECT_FALSE(clock.is_expired(0, TIMEOUT));
-  EXPECT_FALSE(clock.is_expired(UINT32_MAX, TIMEOUT));
-}
-
-TEST(StallClock, ExpiresAtExactlyTheTimeout) {
-  StallClock clock;
-  clock.start(1000);
-  EXPECT_TRUE(clock.is_running());
-  EXPECT_FALSE(clock.is_expired(1000, TIMEOUT));
-  EXPECT_FALSE(clock.is_expired(1000 + TIMEOUT - 1, TIMEOUT));
-  EXPECT_TRUE(clock.is_expired(1000 + TIMEOUT, TIMEOUT));
-  EXPECT_TRUE(clock.is_expired(1000 + TIMEOUT + 1, TIMEOUT));
-  EXPECT_EQ(clock.elapsed(1000 + TIMEOUT), TIMEOUT);
-}
-
-TEST(StallClock, RunningClockKeepsItsStart) {
-  StallClock clock;
-  clock.start(1000);
-  clock.start(5000);
-  EXPECT_TRUE(clock.is_expired(1000 + TIMEOUT, TIMEOUT));
-}
-
-TEST(StallClock, Cleared) {
-  StallClock clock;
-  clock.start(1000);
-  clock.clear();
-  EXPECT_FALSE(clock.is_running());
-  EXPECT_FALSE(clock.is_expired(1000 + TIMEOUT, TIMEOUT));
-  clock.start(50000);
-  EXPECT_FALSE(clock.is_expired(50000 + TIMEOUT - 1, TIMEOUT));
-  EXPECT_TRUE(clock.is_expired(50000 + TIMEOUT, TIMEOUT));
-}
-
-TEST(StallClock, StartAtZeroStillRuns) {
-  StallClock clock;
-  clock.start(0);
-  EXPECT_TRUE(clock.is_running());
-  // Recorded as 1, so it expires one millisecond late
-  EXPECT_FALSE(clock.is_expired(TIMEOUT, TIMEOUT));
-  EXPECT_TRUE(clock.is_expired(TIMEOUT + 1, TIMEOUT));
-}
-
-TEST(StallClock, AcrossMillisWraparound) {
-  StallClock clock;
-  const uint32_t start = UINT32_MAX - 5000;
-  clock.start(start);
-  EXPECT_FALSE(clock.is_expired(UINT32_MAX, TIMEOUT));
-  EXPECT_FALSE(clock.is_expired(start + TIMEOUT - 1, TIMEOUT));  // wrapped to 14998
-  EXPECT_TRUE(clock.is_expired(start + TIMEOUT, TIMEOUT));
-  EXPECT_EQ(clock.elapsed(start + TIMEOUT), TIMEOUT);
-}
-
-}  // namespace esphome::web_server::testing
-
-#endif  // USE_HOST

tests/components/web_server_idf/test_sse_chunk.cpp

@@ -6,9 +6,9 @@
 #include <random>
 #include <string>
 
-#include "esphome/components/web_server/sse_chunk.h"
+#include "esphome/components/web_server_idf/sse_chunk.h"
 
-namespace esphome::web_server::testing {
+namespace esphome::web_server_idf::testing {
 
 // The chunk as try_send_nodefer lays it out: header, fields, first "data: ", then the pieces
 static std::string build_chunk(const char *message, size_t message_len, const char *event, uint32_t id,
@@ -128,4 +128,4 @@ TEST(SseChunk, MatchesReferenceOnRandomMessages) {
   }
 }
 
-}  // namespace esphome::web_server::testing
+}  // namespace esphome::web_server_idf::testing

tests/dummy_main.cpp

@@ -17,7 +17,6 @@ void setup() {
   App.pre_setup(name, sizeof(name) - 1, friendly_name, sizeof(friendly_name) - 1);
   auto *log = new logger::Logger(115200);  // NOLINT
   log->pre_setup();
-  log->set_uart_selection(logger::UART_SELECTION_UART0);
   App.register_component_(log);
 
   auto *wifi = new wifi::WiFiComponent();  // NOLINT