From 3767c5ec91c7ab483a8a68982b82cdd028cc5546 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 9 Feb 2026 16:48:08 -0600
Subject: [PATCH 1/9] [scheduler] Make core timer ID collisions impossible with
 type-safe internal IDs (#13882)

Co-authored-by: Jonathan Swoboda <154711427+swoboda1337@users.noreply.github.com>

From dacc557a16232b4e51e47609fa94ce7f66808c70 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 9 Feb 2026 18:15:48 -0600
Subject: [PATCH 2/9] [uart] Convert parity_to_str to PROGMEM_STRING_TABLE
 (#13805)

---
 esphome/components/uart/uart.cpp | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/esphome/components/uart/uart.cpp b/esphome/components/uart/uart.cpp
index 6cfd6537a59..337fa352c14 100644
--- a/esphome/components/uart/uart.cpp
+++ b/esphome/components/uart/uart.cpp
@@ -3,12 +3,16 @@
 #include "esphome/core/defines.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
+#include "esphome/core/progmem.h"
 #include <cinttypes>
 
 namespace esphome::uart {
 
 static const char *const TAG = "uart";
 
+// UART parity strings indexed by UARTParityOptions enum (0-2): NONE, EVEN, ODD
+PROGMEM_STRING_TABLE(UARTParityStrings, "NONE", "EVEN", "ODD", "UNKNOWN");
+
 void UARTDevice::check_uart_settings(uint32_t baud_rate, uint8_t stop_bits, UARTParityOptions parity,
                                      uint8_t data_bits) {
   if (this->parent_->get_baud_rate() != baud_rate) {
@@ -30,16 +34,7 @@ void UARTDevice::check_uart_settings(uint32_t baud_rate, uint8_t stop_bits, UART
 }
 
 const LogString *parity_to_str(UARTParityOptions parity) {
-  switch (parity) {
-    case UART_CONFIG_PARITY_NONE:
-      return LOG_STR("NONE");
-    case UART_CONFIG_PARITY_EVEN:
-      return LOG_STR("EVEN");
-    case UART_CONFIG_PARITY_ODD:
-      return LOG_STR("ODD");
-    default:
-      return LOG_STR("UNKNOWN");
-  }
+  return UARTParityStrings::get_log_str(static_cast<uint8_t>(parity), UARTParityStrings::LAST_INDEX);
 }
 
 }  // namespace esphome::uart

From 78df8be31fd061cba7a09179db45977aba08e6e5 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 9 Feb 2026 18:16:27 -0600
Subject: [PATCH 3/9] [logger] Resolve thread name once and pass through
 logging chain (#13836)

---
 esphome/components/logger/logger.cpp          |  43 ++++---
 esphome/components/logger/logger.h            | 114 +++++++++---------
 .../logger/task_log_buffer_esp32.cpp          |   3 +-
 .../components/logger/task_log_buffer_esp32.h |   2 +-
 .../logger/task_log_buffer_host.cpp           |  12 +-
 .../components/logger/task_log_buffer_host.h  |   3 +-
 .../logger/task_log_buffer_libretiny.cpp      |   3 +-
 .../logger/task_log_buffer_libretiny.h        |   2 +-
 8 files changed, 93 insertions(+), 89 deletions(-)

diff --git a/esphome/components/logger/logger.cpp b/esphome/components/logger/logger.cpp
index 4cbd4f1bf1b..bb20c403e53 100644
--- a/esphome/components/logger/logger.cpp
+++ b/esphome/components/logger/logger.cpp
@@ -36,8 +36,9 @@ void HOT Logger::log_vprintf_(uint8_t level, const char *tag, int line, const ch
 #endif
 
   // Fast path: main thread, no recursion (99.9% of all logs)
+  // Pass nullptr for thread_name since we already know this is the main task
   if (is_main_task && !this->main_task_recursion_guard_) [[likely]] {
-    this->log_message_to_buffer_and_send_(this->main_task_recursion_guard_, level, tag, line, format, args);
+    this->log_message_to_buffer_and_send_(this->main_task_recursion_guard_, level, tag, line, format, args, nullptr);
     return;
   }
 
@@ -47,21 +48,23 @@ void HOT Logger::log_vprintf_(uint8_t level, const char *tag, int line, const ch
   }
 
   // Non-main thread handling (~0.1% of logs)
+  // Resolve thread name once and pass it through the logging chain.
+  // ESP32/LibreTiny: use TaskHandle_t overload to avoid redundant xTaskGetCurrentTaskHandle()
+  // (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)
-  this->log_vprintf_non_main_thread_(level, tag, line, format, args, current_task);
+  const char *thread_name = get_thread_name_(current_task);
 #else  // USE_HOST
-  this->log_vprintf_non_main_thread_(level, tag, line, format, args);
+  char thread_name_buf[THREAD_NAME_BUF_SIZE];
+  const char *thread_name = this->get_thread_name_(thread_name_buf);
 #endif
+  this->log_vprintf_non_main_thread_(level, tag, line, format, args, thread_name);
 }
 
 // Handles non-main thread logging only
 // Kept separate from hot path to improve instruction cache performance
-#if defined(USE_ESP32) || defined(USE_LIBRETINY)
 void Logger::log_vprintf_non_main_thread_(uint8_t level, const char *tag, int line, const char *format, va_list args,
-                                          TaskHandle_t current_task) {
-#else  // USE_HOST
-void Logger::log_vprintf_non_main_thread_(uint8_t level, const char *tag, int line, const char *format, va_list args) {
-#endif
+                                          const char *thread_name) {
   // Check if already in recursion for this non-main thread/task
   if (this->is_non_main_task_recursive_()) {
     return;
@@ -73,12 +76,8 @@ void Logger::log_vprintf_non_main_thread_(uint8_t level, const char *tag, int li
   bool message_sent = false;
 #ifdef USE_ESPHOME_TASK_LOG_BUFFER
   // For non-main threads/tasks, queue the message for callbacks
-#if defined(USE_ESP32) || defined(USE_LIBRETINY)
   message_sent =
-      this->log_buffer_->send_message_thread_safe(level, tag, static_cast<uint16_t>(line), current_task, format, args);
-#else  // USE_HOST
-  message_sent = this->log_buffer_->send_message_thread_safe(level, tag, static_cast<uint16_t>(line), format, args);
-#endif
+      this->log_buffer_->send_message_thread_safe(level, tag, static_cast<uint16_t>(line), thread_name, format, args);
   if (message_sent) {
     // Enable logger loop to process the buffered message
     // This is safe to call from any context including ISRs
@@ -101,19 +100,27 @@ void Logger::log_vprintf_non_main_thread_(uint8_t level, const char *tag, int li
 #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};
-    this->format_log_to_buffer_with_terminator_(level, tag, line, format, args, buf);
+    this->format_log_to_buffer_with_terminator_(level, tag, line, format, args, buf, thread_name);
     this->write_to_console_(buf);
   }
 
   // RAII guard automatically resets on return
 }
 #else
-// Implementation for all other platforms (single-task, no threading)
+// Implementation for single-task platforms (ESP8266, RP2040, Zephyr)
+// TODO: Zephyr may have multiple threads (work queues, etc.) but uses this single-task path.
+// Logging calls are NOT thread-safe: global_recursion_guard_ is a plain bool and tx_buffer_ has no locking.
+// Not a problem in practice yet since Zephyr has no API support (logs are console-only).
 void HOT Logger::log_vprintf_(uint8_t level, const char *tag, int line, const char *format, va_list args) {  // NOLINT
   if (level > this->level_for(tag) || global_recursion_guard_)
     return;
-
-  this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args);
+#ifdef USE_ZEPHYR
+  char tmp[MAX_POINTER_REPRESENTATION];
+  this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args,
+                                        this->get_thread_name_(tmp));
+#else  // Other single-task platforms don't have thread names, so pass nullptr
+  this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args, nullptr);
+#endif
 }
 #endif  // USE_ESP32 / USE_HOST / USE_LIBRETINY
 
@@ -129,7 +136,7 @@ void Logger::log_vprintf_(uint8_t level, const char *tag, int line, const __Flas
   if (level > this->level_for(tag) || global_recursion_guard_)
     return;
 
-  this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args);
+  this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args, nullptr);
 }
 #endif  // USE_STORE_LOG_STR_IN_FLASH
 
diff --git a/esphome/components/logger/logger.h b/esphome/components/logger/logger.h
index 1678fed5f5e..ecf032ee0ec 100644
--- a/esphome/components/logger/logger.h
+++ b/esphome/components/logger/logger.h
@@ -2,6 +2,7 @@
 
 #include <cstdarg>
 #include <map>
+#include <span>
 #include <type_traits>
 #if defined(USE_ESP32) || defined(USE_HOST)
 #include <pthread.h>
@@ -124,6 +125,10 @@ static constexpr uint16_t MAX_HEADER_SIZE = 128;
 // "0x" + 2 hex digits per byte + '\0'
 static constexpr size_t MAX_POINTER_REPRESENTATION = 2 + sizeof(void *) * 2 + 1;
 
+// Stack buffer size for retrieving thread/task names from the OS
+// macOS allows up to 64 bytes, Linux up to 16
+static constexpr size_t THREAD_NAME_BUF_SIZE = 64;
+
 // Buffer wrapper for log formatting functions
 struct LogBuffer {
   char *data;
@@ -408,34 +413,24 @@ class Logger : public Component {
 
 #if defined(USE_ESP32) || defined(USE_HOST) || defined(USE_LIBRETINY)
   // Handles non-main thread logging only (~0.1% of calls)
-#if defined(USE_ESP32) || defined(USE_LIBRETINY)
-  // ESP32/LibreTiny: Pass task handle to avoid calling xTaskGetCurrentTaskHandle() twice
+  // thread_name is resolved by the caller from the task handle, avoiding redundant lookups
   void log_vprintf_non_main_thread_(uint8_t level, const char *tag, int line, const char *format, va_list args,
-                                    TaskHandle_t current_task);
-#else  // USE_HOST
-  // Host: No task handle parameter needed (not used in send_message_thread_safe)
-  void log_vprintf_non_main_thread_(uint8_t level, const char *tag, int line, const char *format, va_list args);
-#endif
+                                    const char *thread_name);
 #endif
   void process_messages_();
   void write_msg_(const char *msg, uint16_t len);
 
   // Format a log message with printf-style arguments and write it to a buffer with header, footer, and null terminator
+  // thread_name: name of the calling thread/task, or nullptr for main task (callers already know which task they're on)
   inline void HOT format_log_to_buffer_with_terminator_(uint8_t level, const char *tag, int line, const char *format,
-                                                        va_list args, LogBuffer &buf) {
-#if defined(USE_ESP32) || defined(USE_LIBRETINY) || defined(USE_HOST)
-    buf.write_header(level, tag, line, this->get_thread_name_());
-#elif defined(USE_ZEPHYR)
-    char tmp[MAX_POINTER_REPRESENTATION];
-    buf.write_header(level, tag, line, this->get_thread_name_(tmp));
-#else
-    buf.write_header(level, tag, line, nullptr);
-#endif
+                                                        va_list args, LogBuffer &buf, const char *thread_name) {
+    buf.write_header(level, tag, line, thread_name);
     buf.format_body(format, args);
   }
 
 #ifdef USE_STORE_LOG_STR_IN_FLASH
   // Format a log message with flash string format and write it to a buffer with header, footer, and null terminator
+  // ESP8266-only (single-task), thread_name is always nullptr
   inline void HOT format_log_to_buffer_with_terminator_P_(uint8_t level, const char *tag, int line,
                                                           const __FlashStringHelper *format, va_list args,
                                                           LogBuffer &buf) {
@@ -466,9 +461,10 @@ class Logger : public Component {
 
   // Helper to format and send a log message to both console and listeners
   // Template handles both const char* (RAM) and __FlashStringHelper* (flash) format strings
+  // thread_name: name of the calling thread/task, or nullptr for main task
   template<typename FormatType>
   inline void HOT log_message_to_buffer_and_send_(bool &recursion_guard, uint8_t level, const char *tag, int line,
-                                                  FormatType format, va_list args) {
+                                                  FormatType format, va_list args, const char *thread_name) {
     RecursionGuard guard(recursion_guard);
     LogBuffer buf{this->tx_buffer_, this->tx_buffer_size_};
 #ifdef USE_STORE_LOG_STR_IN_FLASH
@@ -477,7 +473,7 @@ class Logger : public Component {
     } else
 #endif
     {
-      this->format_log_to_buffer_with_terminator_(level, tag, line, format, args, buf);
+      this->format_log_to_buffer_with_terminator_(level, tag, line, format, args, buf, thread_name);
     }
     this->notify_listeners_(level, tag, buf);
     this->write_log_buffer_to_console_(buf);
@@ -565,37 +561,57 @@ class Logger : public Component {
   bool global_recursion_guard_{false};  // Simple global recursion guard for single-task platforms
 #endif
 
-#if defined(USE_ESP32) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR)
-  const char *HOT get_thread_name_(
-#ifdef USE_ZEPHYR
-      char *buff
+  // --- get_thread_name_ overloads (per-platform) ---
+
+#if defined(USE_ESP32) || defined(USE_LIBRETINY)
+  // Primary overload - takes a task handle directly to avoid redundant xTaskGetCurrentTaskHandle() calls
+  // when the caller already has the handle (e.g. from the main task check in log_vprintf_)
+  const char *get_thread_name_(TaskHandle_t task) {
+    if (task == this->main_task_) {
+      return nullptr;  // Main task
+    }
+#if defined(USE_ESP32)
+    return pcTaskGetName(task);
+#elif defined(USE_LIBRETINY)
+    return pcTaskGetTaskName(task);
 #endif
-  ) {
-#ifdef USE_ZEPHYR
+  }
+
+  // Convenience overload - gets the current task handle and delegates
+  const char *HOT get_thread_name_() { return this->get_thread_name_(xTaskGetCurrentTaskHandle()); }
+
+#elif defined(USE_HOST)
+  // Takes a caller-provided buffer for the thread name (stack-allocated for thread safety)
+  const char *HOT get_thread_name_(std::span<char> buff) {
+    pthread_t current_thread = pthread_self();
+    if (pthread_equal(current_thread, main_thread_)) {
+      return nullptr;  // Main thread
+    }
+    // For non-main threads, get the thread name into the caller-provided buffer
+    if (pthread_getname_np(current_thread, buff.data(), buff.size()) == 0) {
+      return buff.data();
+    }
+    return nullptr;
+  }
+
+#elif defined(USE_ZEPHYR)
+  const char *HOT get_thread_name_(std::span<char> buff) {
     k_tid_t current_task = k_current_get();
-#else
-    TaskHandle_t current_task = xTaskGetCurrentTaskHandle();
-#endif
     if (current_task == main_task_) {
       return nullptr;  // Main task
-    } else {
-#if defined(USE_ESP32)
-      return pcTaskGetName(current_task);
-#elif defined(USE_LIBRETINY)
-      return pcTaskGetTaskName(current_task);
-#elif defined(USE_ZEPHYR)
-      const char *name = k_thread_name_get(current_task);
-      if (name) {
-        // zephyr print task names only if debug component is present
-        return name;
-      }
-      std::snprintf(buff, MAX_POINTER_REPRESENTATION, "%p", current_task);
-      return buff;
-#endif
     }
+    const char *name = k_thread_name_get(current_task);
+    if (name) {
+      // zephyr print task names only if debug component is present
+      return name;
+    }
+    std::snprintf(buff.data(), buff.size(), "%p", current_task);
+    return buff.data();
   }
 #endif
 
+  // --- Non-main task recursion guards (per-platform) ---
+
 #if defined(USE_ESP32) || defined(USE_HOST)
   // RAII guard for non-main task recursion using pthread TLS
   class NonMainTaskRecursionGuard {
@@ -635,22 +651,6 @@ class Logger : public Component {
   inline RecursionGuard make_non_main_task_guard_() { return RecursionGuard(non_main_task_recursion_guard_); }
 #endif
 
-#ifdef USE_HOST
-  const char *HOT get_thread_name_() {
-    pthread_t current_thread = pthread_self();
-    if (pthread_equal(current_thread, main_thread_)) {
-      return nullptr;  // Main thread
-    }
-    // For non-main threads, return the thread name
-    // We store it in thread-local storage to avoid allocation
-    static thread_local char thread_name_buf[32];
-    if (pthread_getname_np(current_thread, thread_name_buf, sizeof(thread_name_buf)) == 0) {
-      return thread_name_buf;
-    }
-    return nullptr;
-  }
-#endif
-
 #if defined(USE_ESP32) || defined(USE_LIBRETINY)
   // Disable loop when task buffer is empty (with USB CDC check on ESP32)
   inline void disable_loop_when_buffer_empty_() {
diff --git a/esphome/components/logger/task_log_buffer_esp32.cpp b/esphome/components/logger/task_log_buffer_esp32.cpp
index b9dfe45b7fa..56c0a4ae2d4 100644
--- a/esphome/components/logger/task_log_buffer_esp32.cpp
+++ b/esphome/components/logger/task_log_buffer_esp32.cpp
@@ -59,7 +59,7 @@ void TaskLogBuffer::release_message_main_loop(void *token) {
   last_processed_counter_ = message_counter_.load(std::memory_order_relaxed);
 }
 
-bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, TaskHandle_t task_handle,
+bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
                                              const char *format, va_list args) {
   // First, calculate the exact length needed using a null buffer (no actual writing)
   va_list args_copy;
@@ -95,7 +95,6 @@ bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uin
   // 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
-  const char *thread_name = pcTaskGetName(task_handle);
   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
diff --git a/esphome/components/logger/task_log_buffer_esp32.h b/esphome/components/logger/task_log_buffer_esp32.h
index fde9bd60d5e..6c1bafaeba3 100644
--- a/esphome/components/logger/task_log_buffer_esp32.h
+++ b/esphome/components/logger/task_log_buffer_esp32.h
@@ -58,7 +58,7 @@ class TaskLogBuffer {
   void release_message_main_loop(void *token);
 
   // Thread-safe - send a message to the ring buffer from any thread
-  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, TaskHandle_t task_handle,
+  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
                                 const char *format, va_list args);
 
   // Check if there are messages ready to be processed using an atomic counter for performance
diff --git a/esphome/components/logger/task_log_buffer_host.cpp b/esphome/components/logger/task_log_buffer_host.cpp
index 0660aeb0611..676686304a3 100644
--- a/esphome/components/logger/task_log_buffer_host.cpp
+++ b/esphome/components/logger/task_log_buffer_host.cpp
@@ -70,8 +70,8 @@ void TaskLogBufferHost::commit_write_slot_(int slot_index) {
   }
 }
 
-bool TaskLogBufferHost::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *format,
-                                                 va_list args) {
+bool TaskLogBufferHost::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
+                                                 const char *format, va_list args) {
   // Acquire a slot
   int slot_index = this->acquire_write_slot_();
   if (slot_index < 0) {
@@ -85,11 +85,9 @@ bool TaskLogBufferHost::send_message_thread_safe(uint8_t level, const char *tag,
   msg.tag = tag;
   msg.line = line;
 
-  // Get thread name using pthread
-  char thread_name_buf[LogMessage::MAX_THREAD_NAME_SIZE];
-  // pthread_getname_np works the same on Linux and macOS
-  if (pthread_getname_np(pthread_self(), thread_name_buf, sizeof(thread_name_buf)) == 0) {
-    strncpy(msg.thread_name, thread_name_buf, sizeof(msg.thread_name) - 1);
+  // 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';
diff --git a/esphome/components/logger/task_log_buffer_host.h b/esphome/components/logger/task_log_buffer_host.h
index d421d50ec6a..f8e4ee7bee5 100644
--- a/esphome/components/logger/task_log_buffer_host.h
+++ b/esphome/components/logger/task_log_buffer_host.h
@@ -86,7 +86,8 @@ class TaskLogBufferHost {
 
   // Thread-safe - send a message to the buffer from any thread
   // Returns true if message was queued, false if buffer is full
-  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *format, va_list args);
+  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
+                                const char *format, va_list args);
 
   // Check if there are messages ready to be processed
   inline bool HOT has_messages() const {
diff --git a/esphome/components/logger/task_log_buffer_libretiny.cpp b/esphome/components/logger/task_log_buffer_libretiny.cpp
index 580066e621d..5a22857dcb1 100644
--- a/esphome/components/logger/task_log_buffer_libretiny.cpp
+++ b/esphome/components/logger/task_log_buffer_libretiny.cpp
@@ -101,7 +101,7 @@ void TaskLogBufferLibreTiny::release_message_main_loop() {
 }
 
 bool TaskLogBufferLibreTiny::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line,
-                                                      TaskHandle_t task_handle, const char *format, va_list args) {
+                                                      const char *thread_name, const char *format, va_list args) {
   // First, calculate the exact length needed using a null buffer (no actual writing)
   va_list args_copy;
   va_copy(args_copy, args);
@@ -162,7 +162,6 @@ bool TaskLogBufferLibreTiny::send_message_thread_safe(uint8_t level, const char
   msg->line = line;
 
   // Store the thread name now to avoid crashes if task is deleted before processing
-  const char *thread_name = pcTaskGetTaskName(task_handle);
   if (thread_name != nullptr) {
     strncpy(msg->thread_name, thread_name, sizeof(msg->thread_name) - 1);
     msg->thread_name[sizeof(msg->thread_name) - 1] = '\0';
diff --git a/esphome/components/logger/task_log_buffer_libretiny.h b/esphome/components/logger/task_log_buffer_libretiny.h
index bf6b2d2fa4b..bf315e828a5 100644
--- a/esphome/components/logger/task_log_buffer_libretiny.h
+++ b/esphome/components/logger/task_log_buffer_libretiny.h
@@ -70,7 +70,7 @@ class TaskLogBufferLibreTiny {
   void release_message_main_loop();
 
   // Thread-safe - send a message to the buffer from any thread
-  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, TaskHandle_t task_handle,
+  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
                                 const char *format, va_list args);
 
   // Fast check using volatile counter - no lock needed

From bcd4a9fc39a3a35e4ea58d28f2bfc9495e7790bd Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 9 Feb 2026 18:20:53 -0600
Subject: [PATCH 4/9] [pylontech] Batch UART reads to reduce loop overhead
 (#13824)

---
 esphome/components/pylontech/pylontech.cpp | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/esphome/components/pylontech/pylontech.cpp b/esphome/components/pylontech/pylontech.cpp
index 1dc7caaf166..d7242532564 100644
--- a/esphome/components/pylontech/pylontech.cpp
+++ b/esphome/components/pylontech/pylontech.cpp
@@ -56,17 +56,23 @@ void PylontechComponent::setup() {
 void PylontechComponent::update() { this->write_str("pwr\n"); }
 
 void PylontechComponent::loop() {
-  if (this->available() > 0) {
+  int avail = this->available();
+  if (avail > 0) {
     // pylontech sends a lot of data very suddenly
     // we need to quickly put it all into our own buffer, otherwise the uart's buffer will overflow
-    uint8_t data;
     int recv = 0;
-    while (this->available() > 0) {
-      if (this->read_byte(&data)) {
-        buffer_[buffer_index_write_] += (char) data;
-        recv++;
-        if (buffer_[buffer_index_write_].back() == static_cast<char>(ASCII_LF) ||
-            buffer_[buffer_index_write_].length() >= MAX_DATA_LENGTH_BYTES) {
+    uint8_t buf[64];
+    while (avail > 0) {
+      size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+      if (!this->read_array(buf, to_read)) {
+        break;
+      }
+      avail -= to_read;
+      recv += to_read;
+
+      for (size_t i = 0; i < to_read; i++) {
+        buffer_[buffer_index_write_] += (char) buf[i];
+        if (buf[i] == ASCII_LF || buffer_[buffer_index_write_].length() >= MAX_DATA_LENGTH_BYTES) {
           // complete line received
           buffer_index_write_ = (buffer_index_write_ + 1) % NUM_BUFFERS;
         }

From 2edfcf278fb8cb549b175701b4a70fe96c742eda Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 9 Feb 2026 18:21:10 -0600
Subject: [PATCH 5/9] [hlk_fm22x] Replace per-cycle vector allocation with
 member buffer (#13859)

---
 esphome/components/hlk_fm22x/hlk_fm22x.cpp | 62 +++++++++++++---------
 esphome/components/hlk_fm22x/hlk_fm22x.h   | 10 ++--
 2 files changed, 45 insertions(+), 27 deletions(-)

diff --git a/esphome/components/hlk_fm22x/hlk_fm22x.cpp b/esphome/components/hlk_fm22x/hlk_fm22x.cpp
index c0f14c7105c..18d26f057a8 100644
--- a/esphome/components/hlk_fm22x/hlk_fm22x.cpp
+++ b/esphome/components/hlk_fm22x/hlk_fm22x.cpp
@@ -1,20 +1,16 @@
 #include "hlk_fm22x.h"
 #include "esphome/core/log.h"
 #include "esphome/core/helpers.h"
-#include <array>
 #include <cinttypes>
 
 namespace esphome::hlk_fm22x {
 
 static const char *const TAG = "hlk_fm22x";
 
-// Maximum response size is 36 bytes (VERIFY reply: face_id + 32-byte name)
-static constexpr size_t HLK_FM22X_MAX_RESPONSE_SIZE = 36;
-
 void HlkFm22xComponent::setup() {
   ESP_LOGCONFIG(TAG, "Setting up HLK-FM22X...");
   this->set_enrolling_(false);
-  while (this->available()) {
+  while (this->available() > 0) {
     this->read();
   }
   this->defer([this]() { this->send_command_(HlkFm22xCommand::GET_STATUS); });
@@ -35,7 +31,7 @@ void HlkFm22xComponent::update() {
 }
 
 void HlkFm22xComponent::enroll_face(const std::string &name, HlkFm22xFaceDirection direction) {
-  if (name.length() > 31) {
+  if (name.length() > HLK_FM22X_NAME_SIZE - 1) {
     ESP_LOGE(TAG, "enroll_face(): name too long '%s'", name.c_str());
     return;
   }
@@ -88,7 +84,7 @@ void HlkFm22xComponent::send_command_(HlkFm22xCommand command, const uint8_t *da
   }
   this->wait_cycles_ = 0;
   this->active_command_ = command;
-  while (this->available())
+  while (this->available() > 0)
     this->read();
   this->write((uint8_t) (START_CODE >> 8));
   this->write((uint8_t) (START_CODE & 0xFF));
@@ -137,17 +133,24 @@ void HlkFm22xComponent::recv_command_() {
   checksum ^= byte;
   length |= byte;
 
-  std::vector<uint8_t> data;
-  data.reserve(length);
+  if (length > HLK_FM22X_MAX_RESPONSE_SIZE) {
+    ESP_LOGE(TAG, "Response too large: %u bytes", length);
+    // Discard exactly the remaining payload and checksum for this frame
+    for (uint16_t i = 0; i < length + 1 && this->available() > 0; ++i)
+      this->read();
+    return;
+  }
+
   for (uint16_t idx = 0; idx < length; ++idx) {
     byte = this->read();
     checksum ^= byte;
-    data.push_back(byte);
+    this->recv_buf_[idx] = byte;
   }
 
 #if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
   char hex_buf[format_hex_pretty_size(HLK_FM22X_MAX_RESPONSE_SIZE)];
-  ESP_LOGV(TAG, "Recv type: 0x%.2X, data: %s", response_type, format_hex_pretty_to(hex_buf, data.data(), data.size()));
+  ESP_LOGV(TAG, "Recv type: 0x%.2X, data: %s", response_type,
+           format_hex_pretty_to(hex_buf, this->recv_buf_.data(), length));
 #endif
 
   byte = this->read();
@@ -157,10 +160,10 @@ void HlkFm22xComponent::recv_command_() {
   }
   switch (response_type) {
     case HlkFm22xResponseType::NOTE:
-      this->handle_note_(data);
+      this->handle_note_(this->recv_buf_.data(), length);
       break;
     case HlkFm22xResponseType::REPLY:
-      this->handle_reply_(data);
+      this->handle_reply_(this->recv_buf_.data(), length);
       break;
     default:
       ESP_LOGW(TAG, "Unexpected response type: 0x%.2X", response_type);
@@ -168,11 +171,15 @@ void HlkFm22xComponent::recv_command_() {
   }
 }
 
-void HlkFm22xComponent::handle_note_(const std::vector<uint8_t> &data) {
+void HlkFm22xComponent::handle_note_(const uint8_t *data, size_t length) {
+  if (length < 1) {
+    ESP_LOGE(TAG, "Empty note data");
+    return;
+  }
   switch (data[0]) {
     case HlkFm22xNoteType::FACE_STATE:
-      if (data.size() < 17) {
-        ESP_LOGE(TAG, "Invalid face note data size: %u", data.size());
+      if (length < 17) {
+        ESP_LOGE(TAG, "Invalid face note data size: %zu", length);
         break;
       }
       {
@@ -209,9 +216,13 @@ void HlkFm22xComponent::handle_note_(const std::vector<uint8_t> &data) {
   }
 }
 
-void HlkFm22xComponent::handle_reply_(const std::vector<uint8_t> &data) {
+void HlkFm22xComponent::handle_reply_(const uint8_t *data, size_t length) {
   auto expected = this->active_command_;
   this->active_command_ = HlkFm22xCommand::NONE;
+  if (length < 2) {
+    ESP_LOGE(TAG, "Reply too short: %zu bytes", length);
+    return;
+  }
   if (data[0] != (uint8_t) expected) {
     ESP_LOGE(TAG, "Unexpected response command. Expected: 0x%.2X, Received: 0x%.2X", expected, data[0]);
     return;
@@ -238,16 +249,20 @@ void HlkFm22xComponent::handle_reply_(const std::vector<uint8_t> &data) {
   }
   switch (expected) {
     case HlkFm22xCommand::VERIFY: {
+      if (length < 4 + HLK_FM22X_NAME_SIZE) {
+        ESP_LOGE(TAG, "VERIFY response too short: %zu bytes", length);
+        break;
+      }
       int16_t face_id = ((int16_t) data[2] << 8) | data[3];
-      std::string name(data.begin() + 4, data.begin() + 36);
-      ESP_LOGD(TAG, "Face verified. ID: %d, name: %s", face_id, name.c_str());
+      const char *name_ptr = reinterpret_cast<const char *>(data + 4);
+      ESP_LOGD(TAG, "Face verified. ID: %d, name: %.*s", face_id, (int) HLK_FM22X_NAME_SIZE, name_ptr);
       if (this->last_face_id_sensor_ != nullptr) {
         this->last_face_id_sensor_->publish_state(face_id);
       }
       if (this->last_face_name_text_sensor_ != nullptr) {
-        this->last_face_name_text_sensor_->publish_state(name);
+        this->last_face_name_text_sensor_->publish_state(name_ptr, HLK_FM22X_NAME_SIZE);
       }
-      this->face_scan_matched_callback_.call(face_id, name);
+      this->face_scan_matched_callback_.call(face_id, std::string(name_ptr, HLK_FM22X_NAME_SIZE));
       break;
     }
     case HlkFm22xCommand::ENROLL: {
@@ -266,9 +281,8 @@ void HlkFm22xComponent::handle_reply_(const std::vector<uint8_t> &data) {
       this->defer([this]() { this->send_command_(HlkFm22xCommand::GET_VERSION); });
       break;
     case HlkFm22xCommand::GET_VERSION:
-      if (this->version_text_sensor_ != nullptr) {
-        std::string version(data.begin() + 2, data.end());
-        this->version_text_sensor_->publish_state(version);
+      if (this->version_text_sensor_ != nullptr && length > 2) {
+        this->version_text_sensor_->publish_state(reinterpret_cast<const char *>(data + 2), length - 2);
       }
       this->defer([this]() { this->get_face_count_(); });
       break;
diff --git a/esphome/components/hlk_fm22x/hlk_fm22x.h b/esphome/components/hlk_fm22x/hlk_fm22x.h
index 9c981d3c445..0ea4636281c 100644
--- a/esphome/components/hlk_fm22x/hlk_fm22x.h
+++ b/esphome/components/hlk_fm22x/hlk_fm22x.h
@@ -7,12 +7,15 @@
 #include "esphome/components/text_sensor/text_sensor.h"
 #include "esphome/components/uart/uart.h"
 
+#include <array>
 #include <utility>
-#include <vector>
 
 namespace esphome::hlk_fm22x {
 
 static const uint16_t START_CODE = 0xEFAA;
+static constexpr size_t HLK_FM22X_NAME_SIZE = 32;
+// Maximum response payload: command(1) + result(1) + face_id(2) + name(32) = 36
+static constexpr size_t HLK_FM22X_MAX_RESPONSE_SIZE = 36;
 enum HlkFm22xCommand {
   NONE = 0x00,
   RESET = 0x10,
@@ -118,10 +121,11 @@ class HlkFm22xComponent : public PollingComponent, public uart::UARTDevice {
   void get_face_count_();
   void send_command_(HlkFm22xCommand command, const uint8_t *data = nullptr, size_t size = 0);
   void recv_command_();
-  void handle_note_(const std::vector<uint8_t> &data);
-  void handle_reply_(const std::vector<uint8_t> &data);
+  void handle_note_(const uint8_t *data, size_t length);
+  void handle_reply_(const uint8_t *data, size_t length);
   void set_enrolling_(bool enrolling);
 
+  std::array<uint8_t, HLK_FM22X_MAX_RESPONSE_SIZE> recv_buf_;
   HlkFm22xCommand active_command_ = HlkFm22xCommand::NONE;
   uint16_t wait_cycles_ = 0;
   sensor::Sensor *face_count_sensor_{nullptr};

From 57b85a840017e6aa8662c1a0228bcb50052a597a Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 9 Feb 2026 18:24:20 -0600
Subject: [PATCH 6/9] [dlms_meter] Batch UART reads to reduce per-loop overhead
 (#13828)

Co-authored-by: Jonathan Swoboda <154711427+swoboda1337@users.noreply.github.com>
---
 esphome/components/dlms_meter/dlms_meter.cpp | 27 +++++++++++++++-----
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/esphome/components/dlms_meter/dlms_meter.cpp b/esphome/components/dlms_meter/dlms_meter.cpp
index 6aa465143e5..11d05b3a088 100644
--- a/esphome/components/dlms_meter/dlms_meter.cpp
+++ b/esphome/components/dlms_meter/dlms_meter.cpp
@@ -28,15 +28,28 @@ void DlmsMeterComponent::dump_config() {
 
 void DlmsMeterComponent::loop() {
   // Read while data is available, netznoe uses two frames so allow 2x max frame length
-  while (this->available()) {
-    if (this->receive_buffer_.size() >= MBUS_MAX_FRAME_LENGTH * 2) {
+  size_t avail = this->available();
+  if (avail > 0) {
+    size_t remaining = MBUS_MAX_FRAME_LENGTH * 2 - this->receive_buffer_.size();
+    if (remaining == 0) {
       ESP_LOGW(TAG, "Receive buffer full, dropping remaining bytes");
-      break;
+    } else {
+      // Read all available bytes in batches to reduce UART call overhead.
+      // Cap reads to remaining buffer capacity.
+      if (avail > remaining) {
+        avail = remaining;
+      }
+      uint8_t buf[64];
+      while (avail > 0) {
+        size_t to_read = std::min(avail, sizeof(buf));
+        if (!this->read_array(buf, to_read)) {
+          break;
+        }
+        avail -= to_read;
+        this->receive_buffer_.insert(this->receive_buffer_.end(), buf, buf + to_read);
+        this->last_read_ = millis();
+      }
     }
-    uint8_t c;
-    this->read_byte(&c);
-    this->receive_buffer_.push_back(c);
-    this->last_read_ = millis();
   }
 
   if (!this->receive_buffer_.empty() && millis() - this->last_read_ > this->read_timeout_) {

From 01a90074ba94e9661aa077ba272bc6e2d350ee51 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 9 Feb 2026 18:25:34 -0600
Subject: [PATCH 7/9] [ld2420] Batch UART reads to reduce loop overhead
 (#13821)

Co-authored-by: Jonathan Swoboda <154711427+swoboda1337@users.noreply.github.com>
---
 esphome/components/ld2420/ld2420.cpp | 22 ++++++++++++++++++++--
 esphome/components/ld2420/ld2420.h   |  2 ++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/esphome/components/ld2420/ld2420.cpp b/esphome/components/ld2420/ld2420.cpp
index 10c623bce06..69b69f4a61e 100644
--- a/esphome/components/ld2420/ld2420.cpp
+++ b/esphome/components/ld2420/ld2420.cpp
@@ -335,9 +335,10 @@ void LD2420Component::revert_config_action() {
 
 void LD2420Component::loop() {
   // If there is a active send command do not process it here, the send command call will handle it.
-  while (!this->cmd_active_ && this->available()) {
-    this->readline_(this->read(), this->buffer_data_, MAX_LINE_LENGTH);
+  if (this->cmd_active_) {
+    return;
   }
+  this->read_batch_(this->buffer_data_);
 }
 
 void LD2420Component::update_radar_data(uint16_t const *gate_energy, uint8_t sample_number) {
@@ -539,6 +540,23 @@ void LD2420Component::handle_simple_mode_(const uint8_t *inbuf, int len) {
   }
 }
 
+void LD2420Component::read_batch_(std::span<uint8_t, MAX_LINE_LENGTH> buffer) {
+  // Read all available bytes in batches to reduce UART call overhead.
+  size_t avail = this->available();
+  uint8_t buf[MAX_LINE_LENGTH];
+  while (avail > 0) {
+    size_t to_read = std::min(avail, sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
+
+    for (size_t i = 0; i < to_read; i++) {
+      this->readline_(buf[i], buffer.data(), buffer.size());
+    }
+  }
+}
+
 void LD2420Component::handle_ack_data_(uint8_t *buffer, int len) {
   this->cmd_reply_.command = buffer[CMD_FRAME_COMMAND];
   this->cmd_reply_.length = buffer[CMD_FRAME_DATA_LENGTH];
diff --git a/esphome/components/ld2420/ld2420.h b/esphome/components/ld2420/ld2420.h
index 50ddf45264a..6d81f864970 100644
--- a/esphome/components/ld2420/ld2420.h
+++ b/esphome/components/ld2420/ld2420.h
@@ -4,6 +4,7 @@
 #include "esphome/components/uart/uart.h"
 #include "esphome/core/automation.h"
 #include "esphome/core/helpers.h"
+#include <span>
 #ifdef USE_TEXT_SENSOR
 #include "esphome/components/text_sensor/text_sensor.h"
 #endif
@@ -165,6 +166,7 @@ class LD2420Component : public Component, public uart::UARTDevice {
   void handle_energy_mode_(uint8_t *buffer, int len);
   void handle_ack_data_(uint8_t *buffer, int len);
   void readline_(int rx_data, uint8_t *buffer, int len);
+  void read_batch_(std::span<uint8_t, MAX_LINE_LENGTH> buffer);
   void set_calibration_(bool state) { this->calibration_ = state; };
   bool get_calibration_() { return this->calibration_; };
 

From 097901e9c89e284e424bb51eb6cc504a07ba261b Mon Sep 17 00:00:00 2001
From: Sean Kelly <xconverge@users.noreply.github.com>
Date: Mon, 9 Feb 2026 16:30:37 -0800
Subject: [PATCH 8/9] [aqi] Fix AQI calculation for specific pm2.5 or pm10
 readings (#13770)

---
 esphome/components/aqi/aqi_calculator.h  | 38 +++++++++++++++++++-----
 esphome/components/aqi/caqi_calculator.h | 30 ++++++++++++++++---
 2 files changed, 56 insertions(+), 12 deletions(-)

diff --git a/esphome/components/aqi/aqi_calculator.h b/esphome/components/aqi/aqi_calculator.h
index 993504c1e94..d624af0432f 100644
--- a/esphome/components/aqi/aqi_calculator.h
+++ b/esphome/components/aqi/aqi_calculator.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <algorithm>
 #include <cmath>
 #include <limits>
 #include "abstract_aqi_calculator.h"
@@ -14,7 +15,11 @@ class AQICalculator : public AbstractAQICalculator {
     float pm2_5_index = calculate_index(pm2_5_value, PM2_5_GRID);
     float pm10_0_index = calculate_index(pm10_0_value, PM10_0_GRID);
 
-    return static_cast<uint16_t>(std::round((pm2_5_index < pm10_0_index) ? pm10_0_index : pm2_5_index));
+    float aqi = std::max(pm2_5_index, pm10_0_index);
+    if (aqi < 0.0f) {
+      aqi = 0.0f;
+    }
+    return static_cast<uint16_t>(std::lround(aqi));
   }
 
  protected:
@@ -22,13 +27,27 @@ class AQICalculator : public AbstractAQICalculator {
 
   static constexpr int INDEX_GRID[NUM_LEVELS][2] = {{0, 50}, {51, 100}, {101, 150}, {151, 200}, {201, 300}, {301, 500}};
 
-  static constexpr float PM2_5_GRID[NUM_LEVELS][2] = {{0.0f, 9.0f},     {9.1f, 35.4f},
-                                                      {35.5f, 55.4f},   {55.5f, 125.4f},
-                                                      {125.5f, 225.4f}, {225.5f, std::numeric_limits<float>::max()}};
+  static constexpr float PM2_5_GRID[NUM_LEVELS][2] = {
+      // clang-format off
+      {0.0f, 9.1f},
+      {9.1f, 35.5f},
+      {35.5f, 55.5f},
+      {55.5f, 125.5f},
+      {125.5f, 225.5f},
+      {225.5f, std::numeric_limits<float>::max()}
+      // clang-format on
+  };
 
-  static constexpr float PM10_0_GRID[NUM_LEVELS][2] = {{0.0f, 54.0f},    {55.0f, 154.0f},
-                                                       {155.0f, 254.0f}, {255.0f, 354.0f},
-                                                       {355.0f, 424.0f}, {425.0f, std::numeric_limits<float>::max()}};
+  static constexpr float PM10_0_GRID[NUM_LEVELS][2] = {
+      // clang-format off
+      {0.0f, 55.0f},
+      {55.0f, 155.0f},
+      {155.0f, 255.0f},
+      {255.0f, 355.0f},
+      {355.0f, 425.0f},
+      {425.0f, std::numeric_limits<float>::max()}
+      // clang-format on
+  };
 
   static float calculate_index(float value, const float array[NUM_LEVELS][2]) {
     int grid_index = get_grid_index(value, array);
@@ -45,7 +64,10 @@ class AQICalculator : public AbstractAQICalculator {
 
   static int get_grid_index(float value, const float array[NUM_LEVELS][2]) {
     for (int i = 0; i < NUM_LEVELS; i++) {
-      if (value >= array[i][0] && value <= array[i][1]) {
+      const bool in_range =
+          (value >= array[i][0]) && ((i == NUM_LEVELS - 1) ? (value <= array[i][1])   // last bucket inclusive
+                                                           : (value < array[i][1]));  // others exclusive on hi
+      if (in_range) {
         return i;
       }
     }
diff --git a/esphome/components/aqi/caqi_calculator.h b/esphome/components/aqi/caqi_calculator.h
index d2ec4bb98f6..fe2efe7059d 100644
--- a/esphome/components/aqi/caqi_calculator.h
+++ b/esphome/components/aqi/caqi_calculator.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <algorithm>
 #include <cmath>
 #include <limits>
 #include "abstract_aqi_calculator.h"
@@ -12,7 +13,11 @@ class CAQICalculator : public AbstractAQICalculator {
     float pm2_5_index = calculate_index(pm2_5_value, PM2_5_GRID);
     float pm10_0_index = calculate_index(pm10_0_value, PM10_0_GRID);
 
-    return static_cast<uint16_t>(std::round((pm2_5_index < pm10_0_index) ? pm10_0_index : pm2_5_index));
+    float aqi = std::max(pm2_5_index, pm10_0_index);
+    if (aqi < 0.0f) {
+      aqi = 0.0f;
+    }
+    return static_cast<uint16_t>(std::lround(aqi));
   }
 
  protected:
@@ -21,10 +26,24 @@ class CAQICalculator : public AbstractAQICalculator {
   static constexpr int INDEX_GRID[NUM_LEVELS][2] = {{0, 25}, {26, 50}, {51, 75}, {76, 100}, {101, 400}};
 
   static constexpr float PM2_5_GRID[NUM_LEVELS][2] = {
-      {0.0f, 15.0f}, {15.1f, 30.0f}, {30.1f, 55.0f}, {55.1f, 110.0f}, {110.1f, std::numeric_limits<float>::max()}};
+      // clang-format off
+      {0.0f, 15.1f},
+      {15.1f, 30.1f},
+      {30.1f, 55.1f},
+      {55.1f, 110.1f},
+      {110.1f, std::numeric_limits<float>::max()}
+      // clang-format on
+  };
 
   static constexpr float PM10_0_GRID[NUM_LEVELS][2] = {
-      {0.0f, 25.0f}, {25.1f, 50.0f}, {50.1f, 90.0f}, {90.1f, 180.0f}, {180.1f, std::numeric_limits<float>::max()}};
+      // clang-format off
+      {0.0f, 25.1f},
+      {25.1f, 50.1f},
+      {50.1f, 90.1f},
+      {90.1f, 180.1f},
+      {180.1f, std::numeric_limits<float>::max()}
+      // clang-format on
+  };
 
   static float calculate_index(float value, const float array[NUM_LEVELS][2]) {
     int grid_index = get_grid_index(value, array);
@@ -42,7 +61,10 @@ class CAQICalculator : public AbstractAQICalculator {
 
   static int get_grid_index(float value, const float array[NUM_LEVELS][2]) {
     for (int i = 0; i < NUM_LEVELS; i++) {
-      if (value >= array[i][0] && value <= array[i][1]) {
+      const bool in_range =
+          (value >= array[i][0]) && ((i == NUM_LEVELS - 1) ? (value <= array[i][1])   // last bucket inclusive
+                                                           : (value < array[i][1]));  // others exclusive on hi
+      if (in_range) {
         return i;
       }
     }

From 87ac263264b02033638abbed3d661ff33ff7bffd Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 9 Feb 2026 18:32:52 -0600
Subject: [PATCH 9/9] [dsmr] Batch UART reads to reduce per-loop overhead
 (#13826)

---
 esphome/components/dsmr/dsmr.cpp | 243 +++++++++++++++++--------------
 esphome/components/dsmr/dsmr.h   |   1 +
 2 files changed, 137 insertions(+), 107 deletions(-)

diff --git a/esphome/components/dsmr/dsmr.cpp b/esphome/components/dsmr/dsmr.cpp
index c78d37bf5ef..20fbd20cd63 100644
--- a/esphome/components/dsmr/dsmr.cpp
+++ b/esphome/components/dsmr/dsmr.cpp
@@ -40,9 +40,7 @@ bool Dsmr::ready_to_request_data_() {
       this->start_requesting_data_();
     }
     if (!this->requesting_data_) {
-      while (this->available()) {
-        this->read();
-      }
+      this->drain_rx_buffer_();
     }
   }
   return this->requesting_data_;
@@ -115,138 +113,169 @@ void Dsmr::stop_requesting_data_() {
     } else {
       ESP_LOGV(TAG, "Stop reading data from P1 port");
     }
-    while (this->available()) {
-      this->read();
-    }
+    this->drain_rx_buffer_();
     this->requesting_data_ = false;
   }
 }
 
+void Dsmr::drain_rx_buffer_() {
+  uint8_t buf[64];
+  int avail;
+  while ((avail = this->available()) > 0) {
+    if (!this->read_array(buf, std::min(static_cast<size_t>(avail), sizeof(buf)))) {
+      break;
+    }
+  }
+}
+
 void Dsmr::reset_telegram_() {
   this->header_found_ = false;
   this->footer_found_ = false;
   this->bytes_read_ = 0;
   this->crypt_bytes_read_ = 0;
   this->crypt_telegram_len_ = 0;
-  this->last_read_time_ = 0;
 }
 
 void Dsmr::receive_telegram_() {
   while (this->available_within_timeout_()) {
-    const char c = this->read();
+    // Read all available bytes in batches to reduce UART call overhead.
+    uint8_t buf[64];
+    int avail = this->available();
+    while (avail > 0) {
+      size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+      if (!this->read_array(buf, to_read))
+        return;
+      avail -= to_read;
 
-    // Find a new telegram header, i.e. forward slash.
-    if (c == '/') {
-      ESP_LOGV(TAG, "Header of telegram found");
-      this->reset_telegram_();
-      this->header_found_ = true;
-    }
-    if (!this->header_found_)
-      continue;
+      for (size_t i = 0; i < to_read; i++) {
+        const char c = static_cast<char>(buf[i]);
 
-    // Check for buffer overflow.
-    if (this->bytes_read_ >= this->max_telegram_len_) {
-      this->reset_telegram_();
-      ESP_LOGE(TAG, "Error: telegram larger than buffer (%d bytes)", this->max_telegram_len_);
-      return;
-    }
+        // Find a new telegram header, i.e. forward slash.
+        if (c == '/') {
+          ESP_LOGV(TAG, "Header of telegram found");
+          this->reset_telegram_();
+          this->header_found_ = true;
+        }
+        if (!this->header_found_)
+          continue;
 
-    // Some v2.2 or v3 meters will send a new value which starts with '('
-    // in a new line, while the value belongs to the previous ObisId. For
-    // proper parsing, remove these new line characters.
-    if (c == '(') {
-      while (true) {
-        auto previous_char = this->telegram_[this->bytes_read_ - 1];
-        if (previous_char == '\n' || previous_char == '\r') {
-          this->bytes_read_--;
-        } else {
-          break;
+        // Check for buffer overflow.
+        if (this->bytes_read_ >= this->max_telegram_len_) {
+          this->reset_telegram_();
+          ESP_LOGE(TAG, "Error: telegram larger than buffer (%d bytes)", this->max_telegram_len_);
+          return;
+        }
+
+        // Some v2.2 or v3 meters will send a new value which starts with '('
+        // in a new line, while the value belongs to the previous ObisId. For
+        // proper parsing, remove these new line characters.
+        if (c == '(') {
+          while (true) {
+            auto previous_char = this->telegram_[this->bytes_read_ - 1];
+            if (previous_char == '\n' || previous_char == '\r') {
+              this->bytes_read_--;
+            } else {
+              break;
+            }
+          }
+        }
+
+        // Store the byte in the buffer.
+        this->telegram_[this->bytes_read_] = c;
+        this->bytes_read_++;
+
+        // Check for a footer, i.e. exclamation mark, followed by a hex checksum.
+        if (c == '!') {
+          ESP_LOGV(TAG, "Footer of telegram found");
+          this->footer_found_ = true;
+          continue;
+        }
+        // Check for the end of the hex checksum, i.e. a newline.
+        if (this->footer_found_ && c == '\n') {
+          // Parse the telegram and publish sensor values.
+          this->parse_telegram();
+          this->reset_telegram_();
+          return;
         }
       }
     }
-
-    // Store the byte in the buffer.
-    this->telegram_[this->bytes_read_] = c;
-    this->bytes_read_++;
-
-    // Check for a footer, i.e. exclamation mark, followed by a hex checksum.
-    if (c == '!') {
-      ESP_LOGV(TAG, "Footer of telegram found");
-      this->footer_found_ = true;
-      continue;
-    }
-    // Check for the end of the hex checksum, i.e. a newline.
-    if (this->footer_found_ && c == '\n') {
-      // Parse the telegram and publish sensor values.
-      this->parse_telegram();
-      this->reset_telegram_();
-      return;
-    }
   }
 }
 
 void Dsmr::receive_encrypted_telegram_() {
   while (this->available_within_timeout_()) {
-    const char c = this->read();
+    // Read all available bytes in batches to reduce UART call overhead.
+    uint8_t buf[64];
+    int avail = this->available();
+    while (avail > 0) {
+      size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+      if (!this->read_array(buf, to_read))
+        return;
+      avail -= to_read;
 
-    // Find a new telegram start byte.
-    if (!this->header_found_) {
-      if ((uint8_t) c != 0xDB) {
-        continue;
+      for (size_t i = 0; i < to_read; i++) {
+        const char c = static_cast<char>(buf[i]);
+
+        // Find a new telegram start byte.
+        if (!this->header_found_) {
+          if ((uint8_t) c != 0xDB) {
+            continue;
+          }
+          ESP_LOGV(TAG, "Start byte 0xDB of encrypted telegram found");
+          this->reset_telegram_();
+          this->header_found_ = true;
+        }
+
+        // Check for buffer overflow.
+        if (this->crypt_bytes_read_ >= this->max_telegram_len_) {
+          this->reset_telegram_();
+          ESP_LOGE(TAG, "Error: encrypted telegram larger than buffer (%d bytes)", this->max_telegram_len_);
+          return;
+        }
+
+        // Store the byte in the buffer.
+        this->crypt_telegram_[this->crypt_bytes_read_] = c;
+        this->crypt_bytes_read_++;
+
+        // Read the length of the incoming encrypted telegram.
+        if (this->crypt_telegram_len_ == 0 && this->crypt_bytes_read_ > 20) {
+          // Complete header + data bytes
+          this->crypt_telegram_len_ = 13 + (this->crypt_telegram_[11] << 8 | this->crypt_telegram_[12]);
+          ESP_LOGV(TAG, "Encrypted telegram length: %d bytes", this->crypt_telegram_len_);
+        }
+
+        // Check for the end of the encrypted telegram.
+        if (this->crypt_telegram_len_ == 0 || this->crypt_bytes_read_ != this->crypt_telegram_len_) {
+          continue;
+        }
+        ESP_LOGV(TAG, "End of encrypted telegram found");
+
+        // Decrypt the encrypted telegram.
+        GCM<AES128> *gcmaes128{new GCM<AES128>()};
+        gcmaes128->setKey(this->decryption_key_.data(), gcmaes128->keySize());
+        // the iv is 8 bytes of the system title + 4 bytes frame counter
+        // system title is at byte 2 and frame counter at byte 15
+        for (int i = 10; i < 14; i++)
+          this->crypt_telegram_[i] = this->crypt_telegram_[i + 4];
+        constexpr uint16_t iv_size{12};
+        gcmaes128->setIV(&this->crypt_telegram_[2], iv_size);
+        gcmaes128->decrypt(reinterpret_cast<uint8_t *>(this->telegram_),
+                           // the ciphertext start at byte 18
+                           &this->crypt_telegram_[18],
+                           // cipher size
+                           this->crypt_bytes_read_ - 17);
+        delete gcmaes128;  // NOLINT(cppcoreguidelines-owning-memory)
+
+        this->bytes_read_ = strnlen(this->telegram_, this->max_telegram_len_);
+        ESP_LOGV(TAG, "Decrypted telegram size: %d bytes", this->bytes_read_);
+        ESP_LOGVV(TAG, "Decrypted telegram: %s", this->telegram_);
+
+        // Parse the decrypted telegram and publish sensor values.
+        this->parse_telegram();
+        this->reset_telegram_();
+        return;
       }
-      ESP_LOGV(TAG, "Start byte 0xDB of encrypted telegram found");
-      this->reset_telegram_();
-      this->header_found_ = true;
     }
-
-    // Check for buffer overflow.
-    if (this->crypt_bytes_read_ >= this->max_telegram_len_) {
-      this->reset_telegram_();
-      ESP_LOGE(TAG, "Error: encrypted telegram larger than buffer (%d bytes)", this->max_telegram_len_);
-      return;
-    }
-
-    // Store the byte in the buffer.
-    this->crypt_telegram_[this->crypt_bytes_read_] = c;
-    this->crypt_bytes_read_++;
-
-    // Read the length of the incoming encrypted telegram.
-    if (this->crypt_telegram_len_ == 0 && this->crypt_bytes_read_ > 20) {
-      // Complete header + data bytes
-      this->crypt_telegram_len_ = 13 + (this->crypt_telegram_[11] << 8 | this->crypt_telegram_[12]);
-      ESP_LOGV(TAG, "Encrypted telegram length: %d bytes", this->crypt_telegram_len_);
-    }
-
-    // Check for the end of the encrypted telegram.
-    if (this->crypt_telegram_len_ == 0 || this->crypt_bytes_read_ != this->crypt_telegram_len_) {
-      continue;
-    }
-    ESP_LOGV(TAG, "End of encrypted telegram found");
-
-    // Decrypt the encrypted telegram.
-    GCM<AES128> *gcmaes128{new GCM<AES128>()};
-    gcmaes128->setKey(this->decryption_key_.data(), gcmaes128->keySize());
-    // the iv is 8 bytes of the system title + 4 bytes frame counter
-    // system title is at byte 2 and frame counter at byte 15
-    for (int i = 10; i < 14; i++)
-      this->crypt_telegram_[i] = this->crypt_telegram_[i + 4];
-    constexpr uint16_t iv_size{12};
-    gcmaes128->setIV(&this->crypt_telegram_[2], iv_size);
-    gcmaes128->decrypt(reinterpret_cast<uint8_t *>(this->telegram_),
-                       // the ciphertext start at byte 18
-                       &this->crypt_telegram_[18],
-                       // cipher size
-                       this->crypt_bytes_read_ - 17);
-    delete gcmaes128;  // NOLINT(cppcoreguidelines-owning-memory)
-
-    this->bytes_read_ = strnlen(this->telegram_, this->max_telegram_len_);
-    ESP_LOGV(TAG, "Decrypted telegram size: %d bytes", this->bytes_read_);
-    ESP_LOGVV(TAG, "Decrypted telegram: %s", this->telegram_);
-
-    // Parse the decrypted telegram and publish sensor values.
-    this->parse_telegram();
-    this->reset_telegram_();
-    return;
   }
 }
 
diff --git a/esphome/components/dsmr/dsmr.h b/esphome/components/dsmr/dsmr.h
index b7e05a22b3e..fafcf62b876 100644
--- a/esphome/components/dsmr/dsmr.h
+++ b/esphome/components/dsmr/dsmr.h
@@ -85,6 +85,7 @@ class Dsmr : public Component, public uart::UARTDevice {
   void receive_telegram_();
   void receive_encrypted_telegram_();
   void reset_telegram_();
+  void drain_rx_buffer_();
 
   /// Wait for UART data to become available within the read timeout.
   ///