pipsolar_teleinfo

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

esphome/__main__.py

@@ -800,6 +800,13 @@ def command_vscode(args: ArgsProtocol) -> int | None:
 
 
 def command_compile(args: ArgsProtocol, config: ConfigType) -> int | None:
+    # Set memory analysis options in config
+    if args.analyze_memory:
+        config.setdefault(CONF_ESPHOME, {})["analyze_memory"] = True
+
+    if args.memory_report:
+        config.setdefault(CONF_ESPHOME, {})["memory_report_file"] = args.memory_report
+
     exit_code = write_cpp(config)
     if exit_code != 0:
         return exit_code
@@ -1284,6 +1291,17 @@ def parse_args(argv):
         help="Only generate source code, do not compile.",
         action="store_true",
     )
+    parser_compile.add_argument(
+        "--analyze-memory",
+        help="Analyze and display memory usage by component after compilation.",
+        action="store_true",
+    )
+    parser_compile.add_argument(
+        "--memory-report",
+        help="Save memory analysis report to a file (supports .json or .txt).",
+        type=str,
+        metavar="FILE",
+    )
 
     parser_upload = subparsers.add_parser(
         "upload",

esphome/analyze_memory/cli.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 
 from collections import defaultdict
 from collections.abc import Callable
+import json
 import sys
 from typing import TYPE_CHECKING
 
@@ -438,6 +439,28 @@ class MemoryAnalyzerCLI(MemoryAnalyzer):
 
         return "\n".join(lines)
 
+    def to_json(self) -> str:
+        """Export analysis results as JSON."""
+        data = {
+            "components": {
+                name: {
+                    "text": mem.text_size,
+                    "rodata": mem.rodata_size,
+                    "data": mem.data_size,
+                    "bss": mem.bss_size,
+                    "flash_total": mem.flash_total,
+                    "ram_total": mem.ram_total,
+                    "symbol_count": mem.symbol_count,
+                }
+                for name, mem in self.components.items()
+            },
+            "totals": {
+                "flash": sum(c.flash_total for c in self.components.values()),
+                "ram": sum(c.ram_total for c in self.components.values()),
+            },
+        }
+        return json.dumps(data, indent=2)
+
     def dump_uncategorized_symbols(self, output_file: str | None = None) -> None:
         """Dump uncategorized symbols for analysis."""
         # Sort by size descending

esphome/codegen.py

@@ -69,6 +69,7 @@ from esphome.cpp_types import (  # noqa: F401
     JsonObjectConst,
     Parented,
     PollingComponent,
+    StringRef,
     arduino_json_ns,
     bool_,
     const_char_ptr,

esphome/components/am43/am43_base.cpp

@@ -1,6 +1,6 @@
 #include "am43_base.h"
+#include "esphome/core/helpers.h"
 #include <cstring>
-#include <cstdio>
 
 namespace esphome {
 namespace am43 {
@@ -8,12 +8,9 @@ namespace am43 {
 const uint8_t START_PACKET[5] = {0x00, 0xff, 0x00, 0x00, 0x9a};
 
 std::string pkt_to_hex(const uint8_t *data, uint16_t len) {
-  char buf[64];
-  memset(buf, 0, 64);
-  for (int i = 0; i < len; i++)
-    sprintf(&buf[i * 2], "%02x", data[i]);
-  std::string ret = buf;
-  return ret;
+  char buf[64];  // format_hex_size(31) = 63, fits 31 bytes of hex data
+  format_hex_to(buf, sizeof(buf), data, len);
+  return buf;
 }
 
 Am43Packet *Am43Encoder::get_battery_level_request() {

esphome/components/anova/anova_base.cpp

@@ -18,31 +18,31 @@ AnovaPacket *AnovaCodec::clean_packet_() {
 
 AnovaPacket *AnovaCodec::get_read_device_status_request() {
   this->current_query_ = READ_DEVICE_STATUS;
-  sprintf((char *) this->packet_.data, "%s", CMD_READ_DEVICE_STATUS);
+  strncpy((char *) this->packet_.data, CMD_READ_DEVICE_STATUS, sizeof(this->packet_.data));
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_read_target_temp_request() {
   this->current_query_ = READ_TARGET_TEMPERATURE;
-  sprintf((char *) this->packet_.data, "%s", CMD_READ_TARGET_TEMP);
+  strncpy((char *) this->packet_.data, CMD_READ_TARGET_TEMP, sizeof(this->packet_.data));
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_read_current_temp_request() {
   this->current_query_ = READ_CURRENT_TEMPERATURE;
-  sprintf((char *) this->packet_.data, "%s", CMD_READ_CURRENT_TEMP);
+  strncpy((char *) this->packet_.data, CMD_READ_CURRENT_TEMP, sizeof(this->packet_.data));
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_read_unit_request() {
   this->current_query_ = READ_UNIT;
-  sprintf((char *) this->packet_.data, "%s", CMD_READ_UNIT);
+  strncpy((char *) this->packet_.data, CMD_READ_UNIT, sizeof(this->packet_.data));
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_read_data_request() {
   this->current_query_ = READ_DATA;
-  sprintf((char *) this->packet_.data, "%s", CMD_READ_DATA);
+  strncpy((char *) this->packet_.data, CMD_READ_DATA, sizeof(this->packet_.data));
   return this->clean_packet_();
 }
 
@@ -50,25 +50,25 @@ AnovaPacket *AnovaCodec::get_set_target_temp_request(float temperature) {
   this->current_query_ = SET_TARGET_TEMPERATURE;
   if (this->fahrenheit_)
     temperature = ctof(temperature);
-  sprintf((char *) this->packet_.data, CMD_SET_TARGET_TEMP, temperature);
+  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), CMD_SET_TARGET_TEMP, temperature);
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_set_unit_request(char unit) {
   this->current_query_ = SET_UNIT;
-  sprintf((char *) this->packet_.data, CMD_SET_TEMP_UNIT, unit);
+  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), CMD_SET_TEMP_UNIT, unit);
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_start_request() {
   this->current_query_ = START;
-  sprintf((char *) this->packet_.data, CMD_START);
+  strncpy((char *) this->packet_.data, CMD_START, sizeof(this->packet_.data));
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_stop_request() {
   this->current_query_ = STOP;
-  sprintf((char *) this->packet_.data, CMD_STOP);
+  strncpy((char *) this->packet_.data, CMD_STOP, sizeof(this->packet_.data));
   return this->clean_packet_();
 }
 

esphome/components/atm90e32/atm90e32.cpp

@@ -158,12 +158,14 @@ void ATM90E32Component::setup() {
 
   if (this->enable_offset_calibration_) {
     // Initialize flash storage for offset calibrations
-    uint32_t o_hash = fnv1_hash(std::string("_offset_calibration_") + this->cs_summary_);
+    uint32_t o_hash = fnv1_hash("_offset_calibration_");
+    o_hash = fnv1_hash_extend(o_hash, this->cs_summary_);
     this->offset_pref_ = global_preferences->make_preference<OffsetCalibration[3]>(o_hash, true);
     this->restore_offset_calibrations_();
 
     // Initialize flash storage for power offset calibrations
-    uint32_t po_hash = fnv1_hash(std::string("_power_offset_calibration_") + this->cs_summary_);
+    uint32_t po_hash = fnv1_hash("_power_offset_calibration_");
+    po_hash = fnv1_hash_extend(po_hash, this->cs_summary_);
     this->power_offset_pref_ = global_preferences->make_preference<PowerOffsetCalibration[3]>(po_hash, true);
     this->restore_power_offset_calibrations_();
   } else {
@@ -183,7 +185,8 @@ void ATM90E32Component::setup() {
 
   if (this->enable_gain_calibration_) {
     // Initialize flash storage for gain calibration
-    uint32_t g_hash = fnv1_hash(std::string("_gain_calibration_") + this->cs_summary_);
+    uint32_t g_hash = fnv1_hash("_gain_calibration_");
+    g_hash = fnv1_hash_extend(g_hash, this->cs_summary_);
     this->gain_calibration_pref_ = global_preferences->make_preference<GainCalibration[3]>(g_hash, true);
     this->restore_gain_calibrations_();
 

esphome/components/audio/audio_reader.cpp

@@ -185,18 +185,16 @@ esp_err_t AudioReader::start(const std::string &uri, AudioFileType &file_type) {
       return err;
     }
 
-    std::string url_string = str_lower_case(url);
-
-    if (str_endswith(url_string, ".wav")) {
+    if (str_endswith_ignore_case(url, ".wav")) {
       file_type = AudioFileType::WAV;
     }
 #ifdef USE_AUDIO_MP3_SUPPORT
-    else if (str_endswith(url_string, ".mp3")) {
+    else if (str_endswith_ignore_case(url, ".mp3")) {
       file_type = AudioFileType::MP3;
     }
 #endif
 #ifdef USE_AUDIO_FLAC_SUPPORT
-    else if (str_endswith(url_string, ".flac")) {
+    else if (str_endswith_ignore_case(url, ".flac")) {
       file_type = AudioFileType::FLAC;
     }
 #endif

esphome/components/bedjet/bedjet_hub.cpp

@@ -3,6 +3,7 @@
 #include "bedjet_hub.h"
 #include "bedjet_child.h"
 #include "bedjet_const.h"
+#include "esphome/components/esp32_ble/ble_uuid.h"
 #include "esphome/core/application.h"
 #include <cinttypes>
 

esphome/components/ccs811/ccs811.cpp

@@ -81,8 +81,8 @@ void CCS811Component::setup() {
            bootloader_version, application_version);
   if (this->version_ != nullptr) {
     char version[20];  // "15.15.15 (0xffff)" is 17 chars, plus NUL, plus wiggle room
-    sprintf(version, "%d.%d.%d (0x%02x)", (application_version >> 12 & 15), (application_version >> 8 & 15),
-            (application_version >> 4 & 15), application_version);
+    buf_append_printf(version, sizeof(version), 0, "%d.%d.%d (0x%02x)", (application_version >> 12 & 15),
+                      (application_version >> 8 & 15), (application_version >> 4 & 15), application_version);
     ESP_LOGD(TAG, "publishing version state: %s", version);
     this->version_->publish_state(version);
   }

esphome/components/ch422g/ch422g.cpp

@@ -133,7 +133,7 @@ bool CH422GGPIOPin::digital_read() { return this->parent_->digital_read(this->pi
 
 void CH422GGPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value ^ this->inverted_); }
 size_t CH422GGPIOPin::dump_summary(char *buffer, size_t len) const {
-  return snprintf(buffer, len, "EXIO%u via CH422G", this->pin_);
+  return buf_append_printf(buffer, len, 0, "EXIO%u via CH422G", this->pin_);
 }
 void CH422GGPIOPin::set_flags(gpio::Flags flags) {
   flags_ = flags;

esphome/components/cse7766/cse7766.cpp

@@ -207,20 +207,24 @@ void CSE7766Component::parse_data_() {
 
 #if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERY_VERBOSE
   {
-    std::string buf = "Parsed:";
+    // Buffer: 7 + 15 + 33 + 15 + 25 = 95 chars max + null, rounded to 128 for safety margin.
+    // Float sizes with %.4f can be up to 11 chars for large values (e.g., 999999.9999).
+    char buf[128];
+    size_t pos = buf_append_printf(buf, sizeof(buf), 0, "Parsed:");
     if (have_voltage) {
-      buf += str_sprintf(" V=%fV", voltage);
+      pos = buf_append_printf(buf, sizeof(buf), pos, " V=%.4fV", voltage);
     }
     if (have_current) {
-      buf += str_sprintf(" I=%fmA (~%fmA)", current * 1000.0f, calculated_current * 1000.0f);
+      pos = buf_append_printf(buf, sizeof(buf), pos, " I=%.4fmA (~%.4fmA)", current * 1000.0f,
+                              calculated_current * 1000.0f);
     }
     if (have_power) {
-      buf += str_sprintf(" P=%fW", power);
+      pos = buf_append_printf(buf, sizeof(buf), pos, " P=%.4fW", power);
     }
     if (energy != 0.0f) {
-      buf += str_sprintf(" E=%fkWh (%u)", energy, cf_pulses);
+      buf_append_printf(buf, sizeof(buf), pos, " E=%.4fkWh (%u)", energy, cf_pulses);
     }
-    ESP_LOGVV(TAG, "%s", buf.c_str());
+    ESP_LOGVV(TAG, "%s", buf);
   }
 #endif
 }

esphome/components/daikin_arc/daikin_arc.cpp

@@ -258,8 +258,9 @@ bool DaikinArcClimate::parse_state_frame_(const uint8_t frame[]) {
   }
 
   char buf[DAIKIN_STATE_FRAME_SIZE * 3 + 1] = {0};
+  size_t pos = 0;
   for (size_t i = 0; i < DAIKIN_STATE_FRAME_SIZE; i++) {
-    sprintf(buf, "%s%02x ", buf, frame[i]);
+    pos = buf_append_printf(buf, sizeof(buf), pos, "%02x ", frame[i]);
   }
   ESP_LOGD(TAG, "FRAME %s", buf);
 
@@ -349,8 +350,9 @@ bool DaikinArcClimate::on_receive(remote_base::RemoteReceiveData data) {
   if (data.expect_item(DAIKIN_HEADER_MARK, DAIKIN_HEADER_SPACE)) {
     valid_daikin_frame = true;
     size_t bytes_count = data.size() / 2 / 8;
-    std::unique_ptr<char[]> buf(new char[bytes_count * 3 + 1]);
-    buf[0] = '\0';
+    size_t buf_size = bytes_count * 3 + 1;
+    std::unique_ptr<char[]> buf(new char[buf_size]());  // value-initialize (zero-fill)
+    size_t buf_pos = 0;
     for (size_t i = 0; i < bytes_count; i++) {
       uint8_t byte = 0;
       for (int8_t bit = 0; bit < 8; bit++) {
@@ -361,19 +363,19 @@ bool DaikinArcClimate::on_receive(remote_base::RemoteReceiveData data) {
           break;
         }
       }
-      sprintf(buf.get(), "%s%02x ", buf.get(), byte);
+      buf_pos = buf_append_printf(buf.get(), buf_size, buf_pos, "%02x ", byte);
     }
     ESP_LOGD(TAG, "WHOLE FRAME %s  size: %d", buf.get(), data.size());
   }
   if (!valid_daikin_frame) {
-    char sbuf[16 * 10 + 1];
-    sbuf[0] = '\0';
+    char sbuf[16 * 10 + 1] = {0};
+    size_t sbuf_pos = 0;
     for (size_t j = 0; j < static_cast<size_t>(data.size()); j++) {
       if ((j - 2) % 16 == 0) {
         if (j > 0) {
           ESP_LOGD(TAG, "DATA %04x: %s", (j - 16 > 0xffff ? 0 : j - 16), sbuf);
         }
-        sbuf[0] = '\0';
+        sbuf_pos = 0;
       }
       char type_ch = ' ';
       // debug_tolerance = 25%
@@ -401,9 +403,10 @@ bool DaikinArcClimate::on_receive(remote_base::RemoteReceiveData data) {
         type_ch = '0';
 
       if (abs(data[j]) > 100000) {
-        sprintf(sbuf, "%s%-5d[%c] ", sbuf, data[j] > 0 ? 99999 : -99999, type_ch);
+        sbuf_pos = buf_append_printf(sbuf, sizeof(sbuf), sbuf_pos, "%-5d[%c] ", data[j] > 0 ? 99999 : -99999, type_ch);
       } else {
-        sprintf(sbuf, "%s%-5d[%c] ", sbuf, (int) (round(data[j] / 10.) * 10), type_ch);
+        sbuf_pos =
+            buf_append_printf(sbuf, sizeof(sbuf), sbuf_pos, "%-5d[%c] ", (int) (round(data[j] / 10.) * 10), type_ch);
       }
       if (j + 1 == static_cast<size_t>(data.size())) {
         ESP_LOGD(TAG, "DATA %04x: %s", (j - 8 > 0xffff ? 0 : j - 8), sbuf);

esphome/components/debug/debug_component.cpp

@@ -30,7 +30,7 @@ void DebugComponent::dump_config() {
 
   char device_info_buffer[DEVICE_INFO_BUFFER_SIZE];
   ESP_LOGD(TAG, "ESPHome version %s", ESPHOME_VERSION);
-  size_t pos = buf_append(device_info_buffer, DEVICE_INFO_BUFFER_SIZE, 0, "%s", ESPHOME_VERSION);
+  size_t pos = buf_append_printf(device_info_buffer, DEVICE_INFO_BUFFER_SIZE, 0, "%s", ESPHOME_VERSION);
 
   this->free_heap_ = get_free_heap_();
   ESP_LOGD(TAG, "Free Heap Size: %" PRIu32 " bytes", this->free_heap_);

esphome/components/debug/debug_component.h

@@ -5,12 +5,6 @@
 #include "esphome/core/helpers.h"
 #include "esphome/core/macros.h"
 #include <span>
-#include <cstdarg>
-#include <cstdio>
-#include <algorithm>
-#ifdef USE_ESP8266
-#include <pgmspace.h>
-#endif
 
 #ifdef USE_SENSOR
 #include "esphome/components/sensor/sensor.h"
@@ -25,40 +19,7 @@ namespace debug {
 static constexpr size_t DEVICE_INFO_BUFFER_SIZE = 256;
 static constexpr size_t RESET_REASON_BUFFER_SIZE = 128;
 
-#ifdef USE_ESP8266
-// ESP8266: Use vsnprintf_P to keep format strings in flash (PROGMEM)
-// Format strings must be wrapped with PSTR() macro
-inline size_t buf_append_p(char *buf, size_t size, size_t pos, PGM_P fmt, ...) {
-  if (pos >= size) {
-    return size;
-  }
-  va_list args;
-  va_start(args, fmt);
-  int written = vsnprintf_P(buf + pos, size - pos, fmt, args);
-  va_end(args);
-  if (written < 0) {
-    return pos;  // encoding error
-  }
-  return std::min(pos + static_cast<size_t>(written), size);
-}
-#define buf_append(buf, size, pos, fmt, ...) buf_append_p(buf, size, pos, PSTR(fmt), ##__VA_ARGS__)
-#else
-/// Safely append formatted string to buffer, returning new position (capped at size)
-__attribute__((format(printf, 4, 5))) inline size_t buf_append(char *buf, size_t size, size_t pos, const char *fmt,
-                                                               ...) {
-  if (pos >= size) {
-    return size;
-  }
-  va_list args;
-  va_start(args, fmt);
-  int written = vsnprintf(buf + pos, size - pos, fmt, args);
-  va_end(args);
-  if (written < 0) {
-    return pos;  // encoding error
-  }
-  return std::min(pos + static_cast<size_t>(written), size);
-}
-#endif
+// buf_append_printf is now provided by esphome/core/helpers.h
 
 class DebugComponent : public PollingComponent {
  public:

esphome/components/debug/debug_esp32.cpp

@@ -173,8 +173,8 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
   uint32_t flash_size = ESP.getFlashChipSize() / 1024;       // NOLINT
   uint32_t flash_speed = ESP.getFlashChipSpeed() / 1000000;  // NOLINT
   ESP_LOGD(TAG, "Flash Chip: Size=%" PRIu32 "kB Speed=%" PRIu32 "MHz Mode=%s", flash_size, flash_speed, flash_mode);
-  pos = buf_append(buf, size, pos, "|Flash: %" PRIu32 "kB Speed:%" PRIu32 "MHz Mode:%s", flash_size, flash_speed,
-                   flash_mode);
+  pos = buf_append_printf(buf, size, pos, "|Flash: %" PRIu32 "kB Speed:%" PRIu32 "MHz Mode:%s", flash_size, flash_speed,
+                          flash_mode);
 #endif
 
   esp_chip_info_t info;
@@ -182,52 +182,52 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
   const char *model = ESPHOME_VARIANT;
 
   // Build features string
-  pos = buf_append(buf, size, pos, "|Chip: %s Features:", model);
+  pos = buf_append_printf(buf, size, pos, "|Chip: %s Features:", model);
   bool first_feature = true;
   for (const auto &feature : CHIP_FEATURES) {
     if (info.features & feature.bit) {
-      pos = buf_append(buf, size, pos, "%s%s", first_feature ? "" : ", ", feature.name);
+      pos = buf_append_printf(buf, size, pos, "%s%s", first_feature ? "" : ", ", feature.name);
       first_feature = false;
       info.features &= ~feature.bit;
     }
   }
   if (info.features != 0) {
-    pos = buf_append(buf, size, pos, "%sOther:0x%" PRIx32, first_feature ? "" : ", ", info.features);
+    pos = buf_append_printf(buf, size, pos, "%sOther:0x%" PRIx32, first_feature ? "" : ", ", info.features);
   }
   ESP_LOGD(TAG, "Chip: Model=%s, Cores=%u, Revision=%u", model, info.cores, info.revision);
-  pos = buf_append(buf, size, pos, " Cores:%u Revision:%u", info.cores, info.revision);
+  pos = buf_append_printf(buf, size, pos, " Cores:%u Revision:%u", info.cores, info.revision);
 
   uint32_t cpu_freq_mhz = arch_get_cpu_freq_hz() / 1000000;
   ESP_LOGD(TAG, "CPU Frequency: %" PRIu32 " MHz", cpu_freq_mhz);
-  pos = buf_append(buf, size, pos, "|CPU Frequency: %" PRIu32 " MHz", cpu_freq_mhz);
+  pos = buf_append_printf(buf, size, pos, "|CPU Frequency: %" PRIu32 " MHz", cpu_freq_mhz);
 
   // Framework detection
 #ifdef USE_ARDUINO
   ESP_LOGD(TAG, "Framework: Arduino");
-  pos = buf_append(buf, size, pos, "|Framework: Arduino");
+  pos = buf_append_printf(buf, size, pos, "|Framework: Arduino");
 #elif defined(USE_ESP32)
   ESP_LOGD(TAG, "Framework: ESP-IDF");
-  pos = buf_append(buf, size, pos, "|Framework: ESP-IDF");
+  pos = buf_append_printf(buf, size, pos, "|Framework: ESP-IDF");
 #else
   ESP_LOGW(TAG, "Framework: UNKNOWN");
-  pos = buf_append(buf, size, pos, "|Framework: UNKNOWN");
+  pos = buf_append_printf(buf, size, pos, "|Framework: UNKNOWN");
 #endif
 
   ESP_LOGD(TAG, "ESP-IDF Version: %s", esp_get_idf_version());
-  pos = buf_append(buf, size, pos, "|ESP-IDF: %s", esp_get_idf_version());
+  pos = buf_append_printf(buf, size, pos, "|ESP-IDF: %s", esp_get_idf_version());
 
   uint8_t mac[6];
   get_mac_address_raw(mac);
   ESP_LOGD(TAG, "EFuse MAC: %02X:%02X:%02X:%02X:%02X:%02X", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
-  pos = buf_append(buf, size, pos, "|EFuse MAC: %02X:%02X:%02X:%02X:%02X:%02X", mac[0], mac[1], mac[2], mac[3], mac[4],
-                   mac[5]);
+  pos = buf_append_printf(buf, size, pos, "|EFuse MAC: %02X:%02X:%02X:%02X:%02X:%02X", mac[0], mac[1], mac[2], mac[3],
+                          mac[4], mac[5]);
 
   char reason_buffer[RESET_REASON_BUFFER_SIZE];
   const char *reset_reason = get_reset_reason_(std::span<char, RESET_REASON_BUFFER_SIZE>(reason_buffer));
-  pos = buf_append(buf, size, pos, "|Reset: %s", reset_reason);
+  pos = buf_append_printf(buf, size, pos, "|Reset: %s", reset_reason);
 
   const char *wakeup_cause = get_wakeup_cause_(std::span<char, RESET_REASON_BUFFER_SIZE>(reason_buffer));
-  pos = buf_append(buf, size, pos, "|Wakeup: %s", wakeup_cause);
+  pos = buf_append_printf(buf, size, pos, "|Wakeup: %s", wakeup_cause);
 
   return pos;
 }

esphome/components/debug/debug_esp8266.cpp

@@ -53,8 +53,8 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
   uint32_t flash_size = ESP.getFlashChipSize() / 1024;       // NOLINT
   uint32_t flash_speed = ESP.getFlashChipSpeed() / 1000000;  // NOLINT
   ESP_LOGD(TAG, "Flash Chip: Size=%" PRIu32 "kB Speed=%" PRIu32 "MHz Mode=%s", flash_size, flash_speed, flash_mode);
-  pos = buf_append(buf, size, pos, "|Flash: %" PRIu32 "kB Speed:%" PRIu32 "MHz Mode:%s", flash_size, flash_speed,
-                   flash_mode);
+  pos = buf_append_printf(buf, size, pos, "|Flash: %" PRIu32 "kB Speed:%" PRIu32 "MHz Mode:%s", flash_size, flash_speed,
+                          flash_mode);
 
 #if !defined(CLANG_TIDY)
   char reason_buffer[RESET_REASON_BUFFER_SIZE];
@@ -77,15 +77,15 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
            chip_id, ESP.getSdkVersion(), ESP.getCoreVersion().c_str(), boot_version, boot_mode, cpu_freq, flash_chip_id,
            reset_reason, ESP.getResetInfo().c_str());
 
-  pos = buf_append(buf, size, pos, "|Chip: 0x%08" PRIX32, chip_id);
-  pos = buf_append(buf, size, pos, "|SDK: %s", ESP.getSdkVersion());
-  pos = buf_append(buf, size, pos, "|Core: %s", ESP.getCoreVersion().c_str());
-  pos = buf_append(buf, size, pos, "|Boot: %u", boot_version);
-  pos = buf_append(buf, size, pos, "|Mode: %u", boot_mode);
-  pos = buf_append(buf, size, pos, "|CPU: %u", cpu_freq);
-  pos = buf_append(buf, size, pos, "|Flash: 0x%08" PRIX32, flash_chip_id);
-  pos = buf_append(buf, size, pos, "|Reset: %s", reset_reason);
-  pos = buf_append(buf, size, pos, "|%s", ESP.getResetInfo().c_str());
+  pos = buf_append_printf(buf, size, pos, "|Chip: 0x%08" PRIX32, chip_id);
+  pos = buf_append_printf(buf, size, pos, "|SDK: %s", ESP.getSdkVersion());
+  pos = buf_append_printf(buf, size, pos, "|Core: %s", ESP.getCoreVersion().c_str());
+  pos = buf_append_printf(buf, size, pos, "|Boot: %u", boot_version);
+  pos = buf_append_printf(buf, size, pos, "|Mode: %u", boot_mode);
+  pos = buf_append_printf(buf, size, pos, "|CPU: %u", cpu_freq);
+  pos = buf_append_printf(buf, size, pos, "|Flash: 0x%08" PRIX32, flash_chip_id);
+  pos = buf_append_printf(buf, size, pos, "|Reset: %s", reset_reason);
+  pos = buf_append_printf(buf, size, pos, "|%s", ESP.getResetInfo().c_str());
 #endif
 
   return pos;

esphome/components/debug/debug_libretiny.cpp

@@ -36,12 +36,12 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
            lt_get_version(), lt_cpu_get_model_name(), lt_cpu_get_model(), lt_cpu_get_freq_mhz(), mac_id,
            lt_get_board_code(), flash_kib, ram_kib, reset_reason);
 
-  pos = buf_append(buf, size, pos, "|Version: %s", LT_BANNER_STR + 10);
-  pos = buf_append(buf, size, pos, "|Reset Reason: %s", reset_reason);
-  pos = buf_append(buf, size, pos, "|Chip Name: %s", lt_cpu_get_model_name());
-  pos = buf_append(buf, size, pos, "|Chip ID: 0x%06" PRIX32, mac_id);
-  pos = buf_append(buf, size, pos, "|Flash: %" PRIu32 " KiB", flash_kib);
-  pos = buf_append(buf, size, pos, "|RAM: %" PRIu32 " KiB", ram_kib);
+  pos = buf_append_printf(buf, size, pos, "|Version: %s", LT_BANNER_STR + 10);
+  pos = buf_append_printf(buf, size, pos, "|Reset Reason: %s", reset_reason);
+  pos = buf_append_printf(buf, size, pos, "|Chip Name: %s", lt_cpu_get_model_name());
+  pos = buf_append_printf(buf, size, pos, "|Chip ID: 0x%06" PRIX32, mac_id);
+  pos = buf_append_printf(buf, size, pos, "|Flash: %" PRIu32 " KiB", flash_kib);
+  pos = buf_append_printf(buf, size, pos, "|RAM: %" PRIu32 " KiB", ram_kib);
 
   return pos;
 }

esphome/components/debug/debug_rp2040.cpp

@@ -19,7 +19,7 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
 
   uint32_t cpu_freq = rp2040.f_cpu();
   ESP_LOGD(TAG, "CPU Frequency: %" PRIu32, cpu_freq);
-  pos = buf_append(buf, size, pos, "|CPU Frequency: %" PRIu32, cpu_freq);
+  pos = buf_append_printf(buf, size, pos, "|CPU Frequency: %" PRIu32, cpu_freq);
 
   return pos;
 }

esphome/components/debug/debug_zephyr.cpp

@@ -20,9 +20,9 @@ static size_t append_reset_reason(char *buf, size_t size, size_t pos, bool set,
     return pos;
   }
   if (pos > 0) {
-    pos = buf_append(buf, size, pos, ", ");
+    pos = buf_append_printf(buf, size, pos, ", ");
   }
-  return buf_append(buf, size, pos, "%s", reason);
+  return buf_append_printf(buf, size, pos, "%s", reason);
 }
 
 static inline uint32_t read_mem_u32(uintptr_t addr) {
@@ -140,7 +140,7 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
   const char *supply_status =
       (nrf_power_mainregstatus_get(NRF_POWER) == NRF_POWER_MAINREGSTATUS_NORMAL) ? "Normal voltage." : "High voltage.";
   ESP_LOGD(TAG, "Main supply status: %s", supply_status);
-  pos = buf_append(buf, size, pos, "|Main supply status: %s", supply_status);
+  pos = buf_append_printf(buf, size, pos, "|Main supply status: %s", supply_status);
 
   // Regulator stage 0
   if (nrf_power_mainregstatus_get(NRF_POWER) == NRF_POWER_MAINREGSTATUS_HIGH) {
@@ -172,16 +172,16 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
         reg0_voltage = "???V";
     }
     ESP_LOGD(TAG, "Regulator stage 0: %s, %s", reg0_type, reg0_voltage);
-    pos = buf_append(buf, size, pos, "|Regulator stage 0: %s, %s", reg0_type, reg0_voltage);
+    pos = buf_append_printf(buf, size, pos, "|Regulator stage 0: %s, %s", reg0_type, reg0_voltage);
   } else {
     ESP_LOGD(TAG, "Regulator stage 0: disabled");
-    pos = buf_append(buf, size, pos, "|Regulator stage 0: disabled");
+    pos = buf_append_printf(buf, size, pos, "|Regulator stage 0: disabled");
   }
 
   // Regulator stage 1
   const char *reg1_type = nrf_power_dcdcen_get(NRF_POWER) ? "DC/DC" : "LDO";
   ESP_LOGD(TAG, "Regulator stage 1: %s", reg1_type);
-  pos = buf_append(buf, size, pos, "|Regulator stage 1: %s", reg1_type);
+  pos = buf_append_printf(buf, size, pos, "|Regulator stage 1: %s", reg1_type);
 
   // USB power state
   const char *usb_state;
@@ -195,7 +195,7 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
     usb_state = "disconnected";
   }
   ESP_LOGD(TAG, "USB power state: %s", usb_state);
-  pos = buf_append(buf, size, pos, "|USB power state: %s", usb_state);
+  pos = buf_append_printf(buf, size, pos, "|USB power state: %s", usb_state);
 
   // Power-fail comparator
   bool enabled;
@@ -300,14 +300,14 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
           break;
       }
       ESP_LOGD(TAG, "Power-fail comparator: %s, VDDH: %s", pof_voltage, vddh_voltage);
-      pos = buf_append(buf, size, pos, "|Power-fail comparator: %s, VDDH: %s", pof_voltage, vddh_voltage);
+      pos = buf_append_printf(buf, size, pos, "|Power-fail comparator: %s, VDDH: %s", pof_voltage, vddh_voltage);
     } else {
       ESP_LOGD(TAG, "Power-fail comparator: %s", pof_voltage);
-      pos = buf_append(buf, size, pos, "|Power-fail comparator: %s", pof_voltage);
+      pos = buf_append_printf(buf, size, pos, "|Power-fail comparator: %s", pof_voltage);
     }
   } else {
     ESP_LOGD(TAG, "Power-fail comparator: disabled");
-    pos = buf_append(buf, size, pos, "|Power-fail comparator: disabled");
+    pos = buf_append_printf(buf, size, pos, "|Power-fail comparator: disabled");
   }
 
   auto package = [](uint32_t value) {

esphome/components/dfrobot_sen0395/commands.cpp

@@ -127,7 +127,9 @@ DetRangeCfgCommand::DetRangeCfgCommand(float min1, float max1, float min2, float
     this->min2_ = min2 = this->max2_ = max2 = this->min3_ = min3 = this->max3_ = max3 = this->min4_ = min4 =
         this->max4_ = max4 = -1;
 
-    this->cmd_ = str_sprintf("detRangeCfg -1 %.0f %.0f", min1 / 0.15, max1 / 0.15);
+    char buf[72];  // max 72: "detRangeCfg -1 "(15) + 8 * (float(5) + space(1)) + null
+    snprintf(buf, sizeof(buf), "detRangeCfg -1 %.0f %.0f", min1 / 0.15, max1 / 0.15);
+    this->cmd_ = buf;
   } else if (min3 < 0 || max3 < 0) {
     this->min1_ = min1 = round(min1 / 0.15) * 0.15;
     this->max1_ = max1 = round(max1 / 0.15) * 0.15;
@@ -135,7 +137,10 @@ DetRangeCfgCommand::DetRangeCfgCommand(float min1, float max1, float min2, float
     this->max2_ = max2 = round(max2 / 0.15) * 0.15;
     this->min3_ = min3 = this->max3_ = max3 = this->min4_ = min4 = this->max4_ = max4 = -1;
 
-    this->cmd_ = str_sprintf("detRangeCfg -1 %.0f %.0f %.0f %.0f", min1 / 0.15, max1 / 0.15, min2 / 0.15, max2 / 0.15);
+    char buf[72];  // max 72: "detRangeCfg -1 "(15) + 8 * (float(5) + space(1)) + null
+    snprintf(buf, sizeof(buf), "detRangeCfg -1 %.0f %.0f %.0f %.0f", min1 / 0.15, max1 / 0.15, min2 / 0.15,
+             max2 / 0.15);
+    this->cmd_ = buf;
   } else if (min4 < 0 || max4 < 0) {
     this->min1_ = min1 = round(min1 / 0.15) * 0.15;
     this->max1_ = max1 = round(max1 / 0.15) * 0.15;
@@ -145,9 +150,10 @@ DetRangeCfgCommand::DetRangeCfgCommand(float min1, float max1, float min2, float
     this->max3_ = max3 = round(max3 / 0.15) * 0.15;
     this->min4_ = min4 = this->max4_ = max4 = -1;
 
-    this->cmd_ = str_sprintf("detRangeCfg -1 "
-                             "%.0f %.0f %.0f %.0f %.0f %.0f",
-                             min1 / 0.15, max1 / 0.15, min2 / 0.15, max2 / 0.15, min3 / 0.15, max3 / 0.15);
+    char buf[72];  // max 72: "detRangeCfg -1 "(15) + 8 * (float(5) + space(1)) + null
+    snprintf(buf, sizeof(buf), "detRangeCfg -1 %.0f %.0f %.0f %.0f %.0f %.0f", min1 / 0.15, max1 / 0.15, min2 / 0.15,
+             max2 / 0.15, min3 / 0.15, max3 / 0.15);
+    this->cmd_ = buf;
   } else {
     this->min1_ = min1 = round(min1 / 0.15) * 0.15;
     this->max1_ = max1 = round(max1 / 0.15) * 0.15;
@@ -158,10 +164,10 @@ DetRangeCfgCommand::DetRangeCfgCommand(float min1, float max1, float min2, float
     this->min4_ = min4 = round(min4 / 0.15) * 0.15;
     this->max4_ = max4 = round(max4 / 0.15) * 0.15;
 
-    this->cmd_ = str_sprintf("detRangeCfg -1 "
-                             "%.0f %.0f %.0f %.0f %.0f %.0f %.0f %.0f",
-                             min1 / 0.15, max1 / 0.15, min2 / 0.15, max2 / 0.15, min3 / 0.15, max3 / 0.15, min4 / 0.15,
-                             max4 / 0.15);
+    char buf[72];  // max 72: "detRangeCfg -1 "(15) + 8 * (float(5) + space(1)) + null
+    snprintf(buf, sizeof(buf), "detRangeCfg -1 %.0f %.0f %.0f %.0f %.0f %.0f %.0f %.0f", min1 / 0.15, max1 / 0.15,
+             min2 / 0.15, max2 / 0.15, min3 / 0.15, max3 / 0.15, min4 / 0.15, max4 / 0.15);
+    this->cmd_ = buf;
   }
 
   this->min1_ = min1;
@@ -203,7 +209,10 @@ SetLatencyCommand::SetLatencyCommand(float delay_after_detection, float delay_af
   delay_after_disappear = std::round(delay_after_disappear / 0.025f) * 0.025f;
   this->delay_after_detection_ = clamp(delay_after_detection, 0.0f, 1638.375f);
   this->delay_after_disappear_ = clamp(delay_after_disappear, 0.0f, 1638.375f);
-  this->cmd_ = str_sprintf("setLatency %.03f %.03f", this->delay_after_detection_, this->delay_after_disappear_);
+  // max 32: "setLatency "(11) + float(8) + " "(1) + float(8) + null, rounded to 32
+  char buf[32];
+  snprintf(buf, sizeof(buf), "setLatency %.03f %.03f", this->delay_after_detection_, this->delay_after_disappear_);
+  this->cmd_ = buf;
 };
 
 uint8_t SetLatencyCommand::on_message(std::string &message) {

esphome/components/dfrobot_sen0395/commands.h

@@ -75,8 +75,8 @@ class SetLatencyCommand : public Command {
 class SensorCfgStartCommand : public Command {
  public:
   SensorCfgStartCommand(bool startup_mode) : startup_mode_(startup_mode) {
-    char tmp_cmd[20] = {0};
-    sprintf(tmp_cmd, "sensorCfgStart %d", startup_mode);
+    char tmp_cmd[20];  // "sensorCfgStart " (15) + "0/1" (1) + null = 17
+    buf_append_printf(tmp_cmd, sizeof(tmp_cmd), 0, "sensorCfgStart %d", startup_mode);
     cmd_ = std::string(tmp_cmd);
   }
   uint8_t on_message(std::string &message) override;
@@ -142,8 +142,8 @@ class SensitivityCommand : public Command {
   SensitivityCommand(uint8_t sensitivity) : sensitivity_(sensitivity) {
     if (sensitivity > 9)
       sensitivity_ = sensitivity = 9;
-    char tmp_cmd[20] = {0};
-    sprintf(tmp_cmd, "setSensitivity %d", sensitivity);
+    char tmp_cmd[20];  // "setSensitivity " (15) + "0-9" (1) + null = 17
+    buf_append_printf(tmp_cmd, sizeof(tmp_cmd), 0, "setSensitivity %d", sensitivity);
     cmd_ = std::string(tmp_cmd);
   };
   uint8_t on_message(std::string &message) override;

esphome/components/display/__init__.py

@@ -63,11 +63,13 @@ def validate_auto_clear(value):
     return cv.boolean(value)
 
 
-BASIC_DISPLAY_SCHEMA = cv.Schema(
-    {
-        cv.Exclusive(CONF_LAMBDA, CONF_LAMBDA): cv.lambda_,
-    }
-).extend(cv.polling_component_schema("1s"))
+def basic_display_schema(default_update_interval: str = "1s") -> cv.Schema:
+    """Create a basic display schema with configurable default update interval."""
+    return cv.Schema(
+        {
+            cv.Exclusive(CONF_LAMBDA, CONF_LAMBDA): cv.lambda_,
+        }
+    ).extend(cv.polling_component_schema(default_update_interval))
 
 
 def _validate_test_card(config):
@@ -81,34 +83,41 @@ def _validate_test_card(config):
     return config
 
 
-FULL_DISPLAY_SCHEMA = BASIC_DISPLAY_SCHEMA.extend(
-    {
-        cv.Optional(CONF_ROTATION): validate_rotation,
-        cv.Exclusive(CONF_PAGES, CONF_LAMBDA): cv.All(
-            cv.ensure_list(
+def full_display_schema(default_update_interval: str = "1s") -> cv.Schema:
+    """Create a full display schema with configurable default update interval."""
+    schema = basic_display_schema(default_update_interval).extend(
+        {
+            cv.Optional(CONF_ROTATION): validate_rotation,
+            cv.Exclusive(CONF_PAGES, CONF_LAMBDA): cv.All(
+                cv.ensure_list(
+                    {
+                        cv.GenerateID(): cv.declare_id(DisplayPage),
+                        cv.Required(CONF_LAMBDA): cv.lambda_,
+                    }
+                ),
+                cv.Length(min=1),
+            ),
+            cv.Optional(CONF_ON_PAGE_CHANGE): automation.validate_automation(
                 {
-                    cv.GenerateID(): cv.declare_id(DisplayPage),
-                    cv.Required(CONF_LAMBDA): cv.lambda_,
+                    cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(
+                        DisplayOnPageChangeTrigger
+                    ),
+                    cv.Optional(CONF_FROM): cv.use_id(DisplayPage),
+                    cv.Optional(CONF_TO): cv.use_id(DisplayPage),
                 }
             ),
-            cv.Length(min=1),
-        ),
-        cv.Optional(CONF_ON_PAGE_CHANGE): automation.validate_automation(
-            {
-                cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(
-                    DisplayOnPageChangeTrigger
-                ),
-                cv.Optional(CONF_FROM): cv.use_id(DisplayPage),
-                cv.Optional(CONF_TO): cv.use_id(DisplayPage),
-            }
-        ),
-        cv.Optional(
-            CONF_AUTO_CLEAR_ENABLED, default=CONF_UNSPECIFIED
-        ): validate_auto_clear,
-        cv.Optional(CONF_SHOW_TEST_CARD): cv.boolean,
-    }
-)
-FULL_DISPLAY_SCHEMA.add_extra(_validate_test_card)
+            cv.Optional(
+                CONF_AUTO_CLEAR_ENABLED, default=CONF_UNSPECIFIED
+            ): validate_auto_clear,
+            cv.Optional(CONF_SHOW_TEST_CARD): cv.boolean,
+        }
+    )
+    schema.add_extra(_validate_test_card)
+    return schema
+
+
+BASIC_DISPLAY_SCHEMA = basic_display_schema("1s")
+FULL_DISPLAY_SCHEMA = full_display_schema("1s")
 
 
 async def setup_display_core_(var, config):

esphome/components/epaper_spi/display.py

@@ -31,6 +31,7 @@ from esphome.const import (
     CONF_TRANSFORM,
     CONF_UPDATE_INTERVAL,
     CONF_WIDTH,
+    SCHEDULER_DONT_RUN,
 )
 from esphome.cpp_generator import RawExpression
 from esphome.final_validate import full_config
@@ -72,12 +73,10 @@ TRANSFORM_OPTIONS = {CONF_MIRROR_X, CONF_MIRROR_Y, CONF_SWAP_XY}
 def model_schema(config):
     model = MODELS[config[CONF_MODEL]]
     class_name = epaper_spi_ns.class_(model.class_name, EPaperBase)
-    minimum_update_interval = update_interval(
-        model.get_default(CONF_MINIMUM_UPDATE_INTERVAL, "1s")
-    )
     cv_dimensions = cv.Optional if model.get_default(CONF_WIDTH) else cv.Required
     return (
-        display.FULL_DISPLAY_SCHEMA.extend(
+        display.full_display_schema("60s")
+        .extend(
             spi.spi_device_schema(
                 cs_pin_required=False,
                 default_mode="MODE0",
@@ -94,9 +93,6 @@ def model_schema(config):
             {
                 cv.Optional(CONF_ROTATION, default=0): validate_rotation,
                 cv.Required(CONF_MODEL): cv.one_of(model.name, upper=True),
-                cv.Optional(CONF_UPDATE_INTERVAL, default=cv.UNDEFINED): cv.All(
-                    update_interval, cv.Range(min=minimum_update_interval)
-                ),
                 cv.Optional(CONF_TRANSFORM): cv.Schema(
                     {
                         cv.Required(CONF_MIRROR_X): cv.boolean,
@@ -150,15 +146,22 @@ def _final_validate(config):
     global_config = full_config.get()
     from esphome.components.lvgl import DOMAIN as LVGL_DOMAIN
 
-    if CONF_LAMBDA not in config and CONF_PAGES not in config:
-        if LVGL_DOMAIN in global_config:
-            if CONF_UPDATE_INTERVAL not in config:
-                config[CONF_UPDATE_INTERVAL] = update_interval("never")
-        else:
-            # If no drawing methods are configured, and LVGL is not enabled, show a test card
-            config[CONF_SHOW_TEST_CARD] = True
-    elif CONF_UPDATE_INTERVAL not in config:
-        config[CONF_UPDATE_INTERVAL] = update_interval("1min")
+    # If no drawing methods are configured, and LVGL is not enabled, show a test card
+    if (
+        CONF_LAMBDA not in config
+        and CONF_PAGES not in config
+        and LVGL_DOMAIN not in global_config
+    ):
+        config[CONF_SHOW_TEST_CARD] = True
+
+    interval = config[CONF_UPDATE_INTERVAL]
+    if interval != SCHEDULER_DONT_RUN:
+        model = MODELS[config[CONF_MODEL]]
+        minimum = update_interval(model.get_default(CONF_MINIMUM_UPDATE_INTERVAL, "1s"))
+        if interval < minimum:
+            raise cv.Invalid(
+                f"update_interval must be at least {minimum} for {model.name}, got {interval}"
+            )
     return config
 
 

esphome/components/esp32/__init__.py

@@ -660,6 +660,9 @@ CONF_LOOP_TASK_STACK_SIZE = "loop_task_stack_size"
 KEY_VFS_SELECT_REQUIRED = "vfs_select_required"
 KEY_VFS_DIR_REQUIRED = "vfs_dir_required"
 
+# Ring buffer IRAM requirement tracking
+KEY_RINGBUF_IN_IRAM = "ringbuf_in_iram"
+
 
 def require_vfs_select() -> None:
     """Mark that VFS select support is required by a component.
@@ -679,6 +682,17 @@ def require_vfs_dir() -> None:
     CORE.data[KEY_VFS_DIR_REQUIRED] = True
 
 
+def enable_ringbuf_in_iram() -> None:
+    """Keep ring buffer functions in IRAM instead of moving them to flash.
+
+    Call this from components that use esphome/core/ring_buffer.cpp and need
+    the ring buffer functions to remain in IRAM for performance reasons
+    (e.g., voice assistants, audio components).
+    This prevents CONFIG_RINGBUF_PLACE_FUNCTIONS_INTO_FLASH from being enabled.
+    """
+    CORE.data[KEY_RINGBUF_IN_IRAM] = True
+
+
 def _parse_idf_component(value: str) -> ConfigType:
     """Parse IDF component shorthand syntax like 'owner/component^version'"""
     # Match operator followed by version-like string (digit or *)
@@ -1090,14 +1104,18 @@ async def to_code(config):
         add_idf_sdkconfig_option("CONFIG_FREERTOS_PLACE_FUNCTIONS_INTO_FLASH", True)
 
     # Place ring buffer functions into flash instead of IRAM by default
-    # This saves IRAM. In ESP-IDF 6.0 flash placement becomes the default.
-    # Users can set ringbuf_in_iram: true as an escape hatch if they encounter issues.
-    if conf[CONF_ADVANCED][CONF_RINGBUF_IN_IRAM]:
-        # User requests ring buffer in IRAM
+    # This saves IRAM but may impact performance for audio/voice components.
+    # Components that need ring buffer in IRAM call enable_ringbuf_in_iram().
+    # Users can also set ringbuf_in_iram: true to force IRAM placement.
+    # In ESP-IDF 6.0 flash placement becomes the default.
+    if conf[CONF_ADVANCED][CONF_RINGBUF_IN_IRAM] or CORE.data.get(
+        KEY_RINGBUF_IN_IRAM, False
+    ):
+        # User config or component requires ring buffer in IRAM for performance
         # IDF 6.0+: will need CONFIG_RINGBUF_PLACE_ISR_FUNCTIONS_INTO_FLASH=n
         add_idf_sdkconfig_option("CONFIG_RINGBUF_PLACE_ISR_FUNCTIONS_INTO_FLASH", False)
     else:
-        # Place in flash to save IRAM (default)
+        # No component needs it - place in flash to save IRAM
         add_idf_sdkconfig_option("CONFIG_RINGBUF_PLACE_FUNCTIONS_INTO_FLASH", True)
 
     # Place heap functions into flash to save IRAM (~4-6KB savings)

esphome/components/esp32/gpio.cpp

@@ -85,7 +85,6 @@ void ESP32InternalGPIOPin::attach_interrupt(void (*func)(void *), void *arg, gpi
       break;
   }
   gpio_set_intr_type(this->get_pin_num(), idf_type);
-  gpio_intr_enable(this->get_pin_num());
   if (!isr_service_installed) {
     auto res = gpio_install_isr_service(ESP_INTR_FLAG_LEVEL3);
     if (res != ESP_OK) {
@@ -95,6 +94,7 @@ void ESP32InternalGPIOPin::attach_interrupt(void (*func)(void *), void *arg, gpi
     isr_service_installed = true;
   }
   gpio_isr_handler_add(this->get_pin_num(), func, arg);
+  gpio_intr_enable(this->get_pin_num());
 }
 
 size_t ESP32InternalGPIOPin::dump_summary(char *buffer, size_t len) const {

esphome/components/esp32/preferences.cpp

@@ -19,16 +19,7 @@ static constexpr size_t KEY_BUFFER_SIZE = 12;
 
 struct NVSData {
   uint32_t key;
-  std::unique_ptr<uint8_t[]> data;
-  size_t len;
-
-  void set_data(const uint8_t *src, size_t size) {
-    if (!this->data || this->len != size) {
-      this->data = std::make_unique<uint8_t[]>(size);
-      this->len = size;
-    }
-    memcpy(this->data.get(), src, size);
-  }
+  SmallInlineBuffer<8> data;  // Most prefs fit in 8 bytes (covers fan, cover, select, etc.)
 };
 
 static std::vector<NVSData> s_pending_save;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
@@ -41,14 +32,14 @@ class ESP32PreferenceBackend : public ESPPreferenceBackend {
     // try find in pending saves and update that
     for (auto &obj : s_pending_save) {
       if (obj.key == this->key) {
-        obj.set_data(data, len);
+        obj.data.set(data, len);
         return true;
       }
     }
     NVSData save{};
     save.key = this->key;
-    save.set_data(data, len);
-    s_pending_save.emplace_back(std::move(save));
+    save.data.set(data, len);
+    s_pending_save.push_back(std::move(save));
     ESP_LOGVV(TAG, "s_pending_save: key: %" PRIu32 ", len: %zu", this->key, len);
     return true;
   }
@@ -56,11 +47,11 @@ class ESP32PreferenceBackend : public ESPPreferenceBackend {
     // try find in pending saves and load from that
     for (auto &obj : s_pending_save) {
       if (obj.key == this->key) {
-        if (obj.len != len) {
+        if (obj.data.size() != len) {
           // size mismatch
           return false;
         }
-        memcpy(data, obj.data.get(), len);
+        memcpy(data, obj.data.data(), len);
         return true;
       }
     }
@@ -136,10 +127,10 @@ class ESP32Preferences : public ESPPreferences {
       snprintf(key_str, sizeof(key_str), "%" PRIu32, save.key);
       ESP_LOGVV(TAG, "Checking if NVS data %s has changed", key_str);
       if (this->is_changed_(this->nvs_handle, save, key_str)) {
-        esp_err_t err = nvs_set_blob(this->nvs_handle, key_str, save.data.get(), save.len);
-        ESP_LOGV(TAG, "sync: key: %s, len: %zu", key_str, save.len);
+        esp_err_t err = nvs_set_blob(this->nvs_handle, key_str, save.data.data(), save.data.size());
+        ESP_LOGV(TAG, "sync: key: %s, len: %zu", key_str, save.data.size());
         if (err != 0) {
-          ESP_LOGV(TAG, "nvs_set_blob('%s', len=%zu) failed: %s", key_str, save.len, esp_err_to_name(err));
+          ESP_LOGV(TAG, "nvs_set_blob('%s', len=%zu) failed: %s", key_str, save.data.size(), esp_err_to_name(err));
           failed++;
           last_err = err;
           last_key = save.key;
@@ -147,7 +138,7 @@ class ESP32Preferences : public ESPPreferences {
         }
         written++;
       } else {
-        ESP_LOGV(TAG, "NVS data not changed skipping %" PRIu32 "  len=%zu", save.key, save.len);
+        ESP_LOGV(TAG, "NVS data not changed skipping %" PRIu32 "  len=%zu", save.key, save.data.size());
         cached++;
       }
       s_pending_save.erase(s_pending_save.begin() + i);
@@ -178,7 +169,7 @@ class ESP32Preferences : public ESPPreferences {
       return true;
     }
     // Check size first before allocating memory
-    if (actual_len != to_save.len) {
+    if (actual_len != to_save.data.size()) {
       return true;
     }
     auto stored_data = std::make_unique<uint8_t[]>(actual_len);
@@ -187,7 +178,7 @@ class ESP32Preferences : public ESPPreferences {
       ESP_LOGV(TAG, "nvs_get_blob('%s') failed: %s", key_str, esp_err_to_name(err));
       return true;
     }
-    return memcmp(to_save.data.get(), stored_data.get(), to_save.len) != 0;
+    return memcmp(to_save.data.data(), stored_data.get(), to_save.data.size()) != 0;
   }
 
   bool reset() override {

esphome/components/esp32_ble/ble.cpp

@@ -98,6 +98,10 @@ void ESP32BLE::advertising_set_service_data(const std::vector<uint8_t> &data) {
 }
 
 void ESP32BLE::advertising_set_manufacturer_data(const std::vector<uint8_t> &data) {
+  this->advertising_set_manufacturer_data(std::span<const uint8_t>(data));
+}
+
+void ESP32BLE::advertising_set_manufacturer_data(std::span<const uint8_t> data) {
   this->advertising_init_();
   this->advertising_->set_manufacturer_data(data);
   this->advertising_start();

esphome/components/esp32_ble/ble.h

@@ -118,6 +118,7 @@ class ESP32BLE : public Component {
   void advertising_start();
   void advertising_set_service_data(const std::vector<uint8_t> &data);
   void advertising_set_manufacturer_data(const std::vector<uint8_t> &data);
+  void advertising_set_manufacturer_data(std::span<const uint8_t> data);
   void advertising_set_appearance(uint16_t appearance) { this->appearance_ = appearance; }
   void advertising_set_service_data_and_name(std::span<const uint8_t> data, bool include_name);
   void advertising_add_service_uuid(ESPBTUUID uuid);

esphome/components/esp32_ble/ble_advertising.cpp

@@ -59,6 +59,10 @@ void BLEAdvertising::set_service_data(const std::vector<uint8_t> &data) {
 }
 
 void BLEAdvertising::set_manufacturer_data(const std::vector<uint8_t> &data) {
+  this->set_manufacturer_data(std::span<const uint8_t>(data));
+}
+
+void BLEAdvertising::set_manufacturer_data(std::span<const uint8_t> data) {
   delete[] this->advertising_data_.p_manufacturer_data;
   this->advertising_data_.p_manufacturer_data = nullptr;
   this->advertising_data_.manufacturer_len = data.size();

esphome/components/esp32_ble/ble_advertising.h

@@ -37,6 +37,7 @@ class BLEAdvertising {
   void set_scan_response(bool scan_response) { this->scan_response_ = scan_response; }
   void set_min_preferred_interval(uint16_t interval) { this->advertising_data_.min_interval = interval; }
   void set_manufacturer_data(const std::vector<uint8_t> &data);
+  void set_manufacturer_data(std::span<const uint8_t> data);
   void set_appearance(uint16_t appearance) { this->advertising_data_.appearance = appearance; }
   void set_service_data(const std::vector<uint8_t> &data);
   void set_service_data(std::span<const uint8_t> data);

esphome/components/esp32_ble_beacon/esp32_ble_beacon.cpp

@@ -1,5 +1,6 @@
 #include "esp32_ble_beacon.h"
 #include "esphome/core/log.h"
+#include "esphome/core/helpers.h"
 
 #ifdef USE_ESP32
 

esphome/components/esp32_ble_server/ble_server_automations.cpp

@@ -15,7 +15,10 @@ Trigger<std::vector<uint8_t>, uint16_t> *BLETriggers::create_characteristic_on_w
   Trigger<std::vector<uint8_t>, uint16_t> *on_write_trigger =  // NOLINT(cppcoreguidelines-owning-memory)
       new Trigger<std::vector<uint8_t>, uint16_t>();
   characteristic->on_write([on_write_trigger](std::span<const uint8_t> data, uint16_t id) {
-    // Convert span to vector for trigger
+    // Convert span to vector for trigger - copy is necessary because:
+    // 1. Trigger stores the data for use in automation actions that execute later
+    // 2. The span is only valid during this callback (points to temporary BLE stack data)
+    // 3. User lambdas in automations need persistent data they can access asynchronously
     on_write_trigger->trigger(std::vector<uint8_t>(data.begin(), data.end()), id);
   });
   return on_write_trigger;
@@ -27,7 +30,10 @@ Trigger<std::vector<uint8_t>, uint16_t> *BLETriggers::create_descriptor_on_write
   Trigger<std::vector<uint8_t>, uint16_t> *on_write_trigger =  // NOLINT(cppcoreguidelines-owning-memory)
       new Trigger<std::vector<uint8_t>, uint16_t>();
   descriptor->on_write([on_write_trigger](std::span<const uint8_t> data, uint16_t id) {
-    // Convert span to vector for trigger
+    // Convert span to vector for trigger - copy is necessary because:
+    // 1. Trigger stores the data for use in automation actions that execute later
+    // 2. The span is only valid during this callback (points to temporary BLE stack data)
+    // 3. User lambdas in automations need persistent data they can access asynchronously
     on_write_trigger->trigger(std::vector<uint8_t>(data.begin(), data.end()), id);
   });
   return on_write_trigger;

esphome/components/esp32_hosted/update/esp32_hosted_update.cpp

@@ -69,7 +69,10 @@ void Esp32HostedUpdate::setup() {
   // Get coprocessor version
   esp_hosted_coprocessor_fwver_t ver_info;
   if (esp_hosted_get_coprocessor_fwversion(&ver_info) == ESP_OK) {
-    this->update_info_.current_version = str_sprintf("%d.%d.%d", ver_info.major1, ver_info.minor1, ver_info.patch1);
+    // 16 bytes: "255.255.255" (11 chars) + null + safety margin
+    char buf[16];
+    snprintf(buf, sizeof(buf), "%d.%d.%d", ver_info.major1, ver_info.minor1, ver_info.patch1);
+    this->update_info_.current_version = buf;
   } else {
     this->update_info_.current_version = "unknown";
   }

esphome/components/esp8266/gpio.cpp

@@ -99,7 +99,7 @@ void ESP8266GPIOPin::pin_mode(gpio::Flags flags) {
 }
 
 size_t ESP8266GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return snprintf(buffer, len, "GPIO%u", this->pin_);
+  return buf_append_printf(buffer, len, 0, "GPIO%u", this->pin_);
 }
 
 bool ESP8266GPIOPin::digital_read() {

esphome/components/ethernet/ethernet_component.cpp

@@ -802,8 +802,8 @@ void EthernetComponent::ksz8081_set_clock_reference_(esp_eth_mac_t *mac) {
   ESPHL_ERROR_CHECK(err, "Read PHY Control 2 failed");
 #if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERY_VERBOSE
   char hex_buf[format_hex_pretty_size(PHY_REG_SIZE)];
-#endif
   ESP_LOGVV(TAG, "KSZ8081 PHY Control 2: %s", format_hex_pretty_to(hex_buf, (uint8_t *) &phy_control_2, PHY_REG_SIZE));
+#endif
 
   /*
    * Bit 7 is `RMII Reference Clock Select`. Default is `0`.
@@ -820,8 +820,10 @@ void EthernetComponent::ksz8081_set_clock_reference_(esp_eth_mac_t *mac) {
     ESPHL_ERROR_CHECK(err, "Write PHY Control 2 failed");
     err = mac->read_phy_reg(mac, this->phy_addr_, KSZ80XX_PC2R_REG_ADDR, &(phy_control_2));
     ESPHL_ERROR_CHECK(err, "Read PHY Control 2 failed");
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERY_VERBOSE
     ESP_LOGVV(TAG, "KSZ8081 PHY Control 2: %s",
               format_hex_pretty_to(hex_buf, (uint8_t *) &phy_control_2, PHY_REG_SIZE));
+#endif
   }
 }
 #endif  // USE_ETHERNET_KSZ8081

esphome/components/event/__init__.py

@@ -90,9 +90,7 @@ async def setup_event_core_(var, config, *, event_types: list[str]):
 
     for conf in config.get(CONF_ON_EVENT, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(
-            trigger, [(cg.std_string, "event_type")], conf
-        )
+        await automation.build_automation(trigger, [(cg.StringRef, "event_type")], conf)
 
     cg.add(var.set_event_types(event_types))
 

esphome/components/event/automation.h

@@ -14,10 +14,10 @@ template<typename... Ts> class TriggerEventAction : public Action<Ts...>, public
   void play(const Ts &...x) override { this->parent_->trigger(this->event_type_.value(x...)); }
 };
 
-class EventTrigger : public Trigger<std::string> {
+class EventTrigger : public Trigger<StringRef> {
  public:
   EventTrigger(Event *event) {
-    event->add_on_event_callback([this](const std::string &event_type) { this->trigger(event_type); });
+    event->add_on_event_callback([this](StringRef event_type) { this->trigger(event_type); });
   }
 };
 

esphome/components/event/event.cpp

@@ -23,7 +23,7 @@ void Event::trigger(const std::string &event_type) {
   }
   this->last_event_type_ = found;
   ESP_LOGD(TAG, "'%s' >> '%s'", this->get_name().c_str(), this->last_event_type_);
-  this->event_callback_.call(event_type);
+  this->event_callback_.call(StringRef(found));
 #if defined(USE_EVENT) && defined(USE_CONTROLLER_REGISTRY)
   ControllerRegistry::notify_event(this);
 #endif
@@ -45,7 +45,7 @@ void Event::set_event_types(const std::vector<const char *> &event_types) {
   this->last_event_type_ = nullptr;  // Reset when types change
 }
 
-void Event::add_on_event_callback(std::function<void(const std::string &event_type)> &&callback) {
+void Event::add_on_event_callback(std::function<void(StringRef event_type)> &&callback) {
   this->event_callback_.add(std::move(callback));
 }
 

esphome/components/event/event.h

@@ -70,10 +70,10 @@ class Event : public EntityBase, public EntityBase_DeviceClass {
   /// Check if an event has been triggered.
   bool has_event() const { return this->last_event_type_ != nullptr; }
 
-  void add_on_event_callback(std::function<void(const std::string &event_type)> &&callback);
+  void add_on_event_callback(std::function<void(StringRef event_type)> &&callback);
 
  protected:
-  LazyCallbackManager<void(const std::string &event_type)> event_callback_;
+  LazyCallbackManager<void(StringRef event_type)> event_callback_;
   FixedVector<const char *> types_;
 
  private:

esphome/components/ezo/ezo.cpp

@@ -160,7 +160,7 @@ void EZOSensor::loop() {
   this->commands_.pop_front();
 }
 
-void EZOSensor::add_command_(const std::string &command, EzoCommandType command_type, uint16_t delay_ms) {
+void EZOSensor::add_command_(const char *command, EzoCommandType command_type, uint16_t delay_ms) {
   std::unique_ptr<EzoCommand> ezo_command(new EzoCommand);
   ezo_command->command = command;
   ezo_command->command_type = command_type;
@@ -169,13 +169,17 @@ void EZOSensor::add_command_(const std::string &command, EzoCommandType command_
 }
 
 void EZOSensor::set_calibration_point_(EzoCalibrationType type, float value) {
-  std::string payload = str_sprintf("Cal,%s,%0.2f", EZO_CALIBRATION_TYPE_STRINGS[type], value);
+  // max 21: "Cal,"(4) + type(4) + ","(1) + float(11) + null; use 24 for safety
+  char payload[24];
+  snprintf(payload, sizeof(payload), "Cal,%s,%0.2f", EZO_CALIBRATION_TYPE_STRINGS[type], value);
   this->add_command_(payload, EzoCommandType::EZO_CALIBRATION, 900);
 }
 
 void EZOSensor::set_address(uint8_t address) {
   if (address > 0 && address < 128) {
-    std::string payload = str_sprintf("I2C,%u", address);
+    // max 8: "I2C,"(4) + uint8(3) + null
+    char payload[8];
+    snprintf(payload, sizeof(payload), "I2C,%u", address);
     this->new_address_ = address;
     this->add_command_(payload, EzoCommandType::EZO_I2C);
   } else {
@@ -194,7 +198,9 @@ void EZOSensor::get_slope() { this->add_command_("Slope,?", EzoCommandType::EZO_
 void EZOSensor::get_t() { this->add_command_("T,?", EzoCommandType::EZO_T); }
 
 void EZOSensor::set_t(float value) {
-  std::string payload = str_sprintf("T,%0.2f", value);
+  // max 14 bytes: "T,"(2) + float with "%0.2f" (up to 11 chars) + null(1); use 16 for alignment
+  char payload[16];
+  snprintf(payload, sizeof(payload), "T,%0.2f", value);
   this->add_command_(payload, EzoCommandType::EZO_T);
 }
 
@@ -215,7 +221,9 @@ void EZOSensor::set_calibration_point_high(float value) {
 }
 
 void EZOSensor::set_calibration_generic(float value) {
-  std::string payload = str_sprintf("Cal,%0.2f", value);
+  // exact 16 bytes: "Cal," (4) + float with "%0.2f" (up to 11 chars, e.g. "-9999999.99") + null (1) = 16
+  char payload[16];
+  snprintf(payload, sizeof(payload), "Cal,%0.2f", value);
   this->add_command_(payload, EzoCommandType::EZO_CALIBRATION, 900);
 }
 
@@ -223,13 +231,11 @@ void EZOSensor::clear_calibration() { this->add_command_("Cal,clear", EzoCommand
 
 void EZOSensor::get_led_state() { this->add_command_("L,?", EzoCommandType::EZO_LED); }
 
-void EZOSensor::set_led_state(bool on) {
-  std::string to_send = "L,";
-  to_send += on ? "1" : "0";
-  this->add_command_(to_send, EzoCommandType::EZO_LED);
-}
+void EZOSensor::set_led_state(bool on) { this->add_command_(on ? "L,1" : "L,0", EzoCommandType::EZO_LED); }
 
-void EZOSensor::send_custom(const std::string &to_send) { this->add_command_(to_send, EzoCommandType::EZO_CUSTOM); }
+void EZOSensor::send_custom(const std::string &to_send) {
+  this->add_command_(to_send.c_str(), EzoCommandType::EZO_CUSTOM);
+}
 
 }  // namespace ezo
 }  // namespace esphome

esphome/components/ezo/ezo.h

@@ -92,7 +92,7 @@ class EZOSensor : public sensor::Sensor, public PollingComponent, public i2c::I2
   std::deque<std::unique_ptr<EzoCommand>> commands_;
   int new_address_;
 
-  void add_command_(const std::string &command, EzoCommandType command_type, uint16_t delay_ms = 300);
+  void add_command_(const char *command, EzoCommandType command_type, uint16_t delay_ms = 300);
 
   void set_calibration_point_(EzoCalibrationType type, float value);
 

esphome/components/ezo_pmp/ezo_pmp.cpp

@@ -318,90 +318,94 @@ void EzoPMP::send_next_command_() {
   switch (this->next_command_) {
     // Read Commands
     case EZO_PMP_COMMAND_READ_DOSING:  // Page 54
-      command_buffer_length = sprintf((char *) command_buffer, "D,?");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "D,?");
       break;
 
     case EZO_PMP_COMMAND_READ_SINGLE_REPORT:  // Single Report (page 53)
-      command_buffer_length = sprintf((char *) command_buffer, "R");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "R");
       break;
 
     case EZO_PMP_COMMAND_READ_MAX_FLOW_RATE:
-      command_buffer_length = sprintf((char *) command_buffer, "DC,?");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "DC,?");
       break;
 
     case EZO_PMP_COMMAND_READ_PAUSE_STATUS:
-      command_buffer_length = sprintf((char *) command_buffer, "P,?");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "P,?");
       break;
 
     case EZO_PMP_COMMAND_READ_TOTAL_VOLUME_DOSED:
-      command_buffer_length = sprintf((char *) command_buffer, "TV,?");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "TV,?");
       break;
 
     case EZO_PMP_COMMAND_READ_ABSOLUTE_TOTAL_VOLUME_DOSED:
-      command_buffer_length = sprintf((char *) command_buffer, "ATV,?");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "ATV,?");
       break;
 
     case EZO_PMP_COMMAND_READ_CALIBRATION_STATUS:
-      command_buffer_length = sprintf((char *) command_buffer, "Cal,?");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "Cal,?");
       break;
 
     case EZO_PMP_COMMAND_READ_PUMP_VOLTAGE:
-      command_buffer_length = sprintf((char *) command_buffer, "PV,?");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "PV,?");
       break;
 
       // Non-Read Commands
 
     case EZO_PMP_COMMAND_FIND:  // Find (page 52)
-      command_buffer_length = sprintf((char *) command_buffer, "Find");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "Find");
       wait_time_for_command = 60000;  // This command will block all updates for a minute
       break;
 
     case EZO_PMP_COMMAND_DOSE_CONTINUOUSLY:  // Continuous Dispensing (page 54)
-      command_buffer_length = sprintf((char *) command_buffer, "D,*");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "D,*");
       break;
 
     case EZO_PMP_COMMAND_CLEAR_TOTAL_VOLUME_DOSED:  // Clear Total Volume Dosed (page 64)
-      command_buffer_length = sprintf((char *) command_buffer, "Clear");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "Clear");
       break;
 
     case EZO_PMP_COMMAND_CLEAR_CALIBRATION:  // Clear Calibration (page 65)
-      command_buffer_length = sprintf((char *) command_buffer, "Cal,clear");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "Cal,clear");
       break;
 
     case EZO_PMP_COMMAND_PAUSE_DOSING:  // Pause (page 61)
-      command_buffer_length = sprintf((char *) command_buffer, "P");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "P");
       break;
 
     case EZO_PMP_COMMAND_STOP_DOSING:  // Stop (page 62)
-      command_buffer_length = sprintf((char *) command_buffer, "X");
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "X");
       break;
 
       // Non-Read commands with parameters
 
     case EZO_PMP_COMMAND_DOSE_VOLUME:  // Volume Dispensing (page 55)
-      command_buffer_length = sprintf((char *) command_buffer, "D,%0.1f", this->next_command_volume_);
+      command_buffer_length =
+          snprintf((char *) command_buffer, sizeof(command_buffer), "D,%0.1f", this->next_command_volume_);
       break;
 
     case EZO_PMP_COMMAND_DOSE_VOLUME_OVER_TIME:  // Dose over time (page 56)
-      command_buffer_length =
-          sprintf((char *) command_buffer, "D,%0.1f,%i", this->next_command_volume_, this->next_command_duration_);
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "D,%0.1f,%i",
+                                       this->next_command_volume_, this->next_command_duration_);
       break;
 
     case EZO_PMP_COMMAND_DOSE_WITH_CONSTANT_FLOW_RATE:  // Constant Flow Rate (page 57)
-      command_buffer_length =
-          sprintf((char *) command_buffer, "DC,%0.1f,%i", this->next_command_volume_, this->next_command_duration_);
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "DC,%0.1f,%i",
+                                       this->next_command_volume_, this->next_command_duration_);
       break;
 
     case EZO_PMP_COMMAND_SET_CALIBRATION_VOLUME:  // Set Calibration Volume (page 65)
-      command_buffer_length = sprintf((char *) command_buffer, "Cal,%0.2f", this->next_command_volume_);
+      command_buffer_length =
+          snprintf((char *) command_buffer, sizeof(command_buffer), "Cal,%0.2f", this->next_command_volume_);
       break;
 
     case EZO_PMP_COMMAND_CHANGE_I2C_ADDRESS:  // Change I2C Address (page 73)
-      command_buffer_length = sprintf((char *) command_buffer, "I2C,%i", this->next_command_duration_);
+      command_buffer_length =
+          snprintf((char *) command_buffer, sizeof(command_buffer), "I2C,%i", this->next_command_duration_);
       break;
 
     case EZO_PMP_COMMAND_EXEC_ARBITRARY_COMMAND_ADDRESS:  // Run an arbitrary command
-      command_buffer_length = sprintf((char *) command_buffer, this->arbitrary_command_, this->next_command_duration_);
+      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), this->arbitrary_command_,
+                                       this->next_command_duration_);
       ESP_LOGI(TAG, "Sending arbitrary command: %s", (char *) command_buffer);
       break;
 

esphome/components/fan/__init__.py

@@ -77,7 +77,7 @@ FanSpeedSetTrigger = fan_ns.class_(
     "FanSpeedSetTrigger", automation.Trigger.template(cg.int_)
 )
 FanPresetSetTrigger = fan_ns.class_(
-    "FanPresetSetTrigger", automation.Trigger.template(cg.std_string)
+    "FanPresetSetTrigger", automation.Trigger.template(cg.StringRef)
 )
 
 FanIsOnCondition = fan_ns.class_("FanIsOnCondition", automation.Condition.template())
@@ -287,7 +287,7 @@ async def setup_fan_core_(var, config):
         await automation.build_automation(trigger, [(cg.int_, "x")], conf)
     for conf in config.get(CONF_ON_PRESET_SET, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [(cg.std_string, "x")], conf)
+        await automation.build_automation(trigger, [(cg.StringRef, "x")], conf)
 
 
 async def register_fan(var, config):

esphome/components/fan/automation.h

@@ -208,7 +208,7 @@ class FanSpeedSetTrigger : public Trigger<int> {
   int last_speed_;
 };
 
-class FanPresetSetTrigger : public Trigger<std::string> {
+class FanPresetSetTrigger : public Trigger<StringRef> {
  public:
   FanPresetSetTrigger(Fan *state) {
     state->add_on_state_callback([this, state]() {
@@ -216,7 +216,7 @@ class FanPresetSetTrigger : public Trigger<std::string> {
       auto should_trigger = preset_mode != this->last_preset_mode_;
       this->last_preset_mode_ = preset_mode;
       if (should_trigger) {
-        this->trigger(std::string(preset_mode));
+        this->trigger(preset_mode);
       }
     });
     this->last_preset_mode_ = state->get_preset_mode();

esphome/components/fan/fan.cpp

@@ -71,7 +71,7 @@ void FanCall::validate_() {
   auto traits = this->parent_.get_traits();
 
   if (this->speed_.has_value()) {
-    this->speed_ = clamp(*this->speed_, 1, traits.supported_speed_count());
+    this->speed_ = clamp(*this->speed_, 1, static_cast<int>(traits.supported_speed_count()));
 
     // https://developers.home-assistant.io/docs/core/entity/fan/#preset-modes
     // "Manually setting a speed must disable any set preset mode"

esphome/components/fan/fan_traits.h

@@ -11,7 +11,7 @@ namespace fan {
 class FanTraits {
  public:
   FanTraits() = default;
-  FanTraits(bool oscillation, bool speed, bool direction, int speed_count)
+  FanTraits(bool oscillation, bool speed, bool direction, uint8_t speed_count)
       : oscillation_(oscillation), speed_(speed), direction_(direction), speed_count_(speed_count) {}
 
   /// Return if this fan supports oscillation.
@@ -23,9 +23,9 @@ class FanTraits {
   /// Set whether this fan supports speed levels.
   void set_speed(bool speed) { this->speed_ = speed; }
   /// Return how many speed levels the fan has
-  int supported_speed_count() const { return this->speed_count_; }
+  uint8_t supported_speed_count() const { return this->speed_count_; }
   /// Set how many speed levels this fan has.
-  void set_supported_speed_count(int speed_count) { this->speed_count_ = speed_count; }
+  void set_supported_speed_count(uint8_t speed_count) { this->speed_count_ = speed_count; }
   /// Return if this fan supports changing direction
   bool supports_direction() const { return this->direction_; }
   /// Set whether this fan supports changing direction
@@ -64,7 +64,7 @@ class FanTraits {
   bool oscillation_{false};
   bool speed_{false};
   bool direction_{false};
-  int speed_count_{};
+  uint8_t speed_count_{};
   std::vector<const char *> preset_modes_{};
 };
 

esphome/components/gdk101/gdk101.cpp

@@ -163,9 +163,10 @@ bool GDK101Component::read_fw_version_(uint8_t *data) {
       return false;
     }
 
-    const std::string fw_version_str = str_sprintf("%d.%d", data[0], data[1]);
-
-    this->fw_version_text_sensor_->publish_state(fw_version_str);
+    // max 8: "255.255" (7 chars) + null
+    char buf[8];
+    snprintf(buf, sizeof(buf), "%d.%d", data[0], data[1]);
+    this->fw_version_text_sensor_->publish_state(buf);
   }
 #endif  // USE_TEXT_SENSOR
   return true;

esphome/components/hbridge/fan/__init__.py

@@ -39,7 +39,7 @@ CONFIG_SCHEMA = (
             cv.Optional(CONF_DECAY_MODE, default="SLOW"): cv.enum(
                 DECAY_MODE_OPTIONS, upper=True
             ),
-            cv.Optional(CONF_SPEED_COUNT, default=100): cv.int_range(min=1),
+            cv.Optional(CONF_SPEED_COUNT, default=100): cv.int_range(min=1, max=255),
             cv.Optional(CONF_ENABLE_PIN): cv.use_id(output.FloatOutput),
             cv.Optional(CONF_PRESET_MODES): validate_preset_modes,
         }

esphome/components/hbridge/fan/hbridge_fan.h

@@ -15,7 +15,7 @@ enum DecayMode {
 
 class HBridgeFan : public Component, public fan::Fan {
  public:
-  HBridgeFan(int speed_count, DecayMode decay_mode) : speed_count_(speed_count), decay_mode_(decay_mode) {}
+  HBridgeFan(uint8_t speed_count, DecayMode decay_mode) : speed_count_(speed_count), decay_mode_(decay_mode) {}
 
   void set_pin_a(output::FloatOutput *pin_a) { pin_a_ = pin_a; }
   void set_pin_b(output::FloatOutput *pin_b) { pin_b_ = pin_b; }
@@ -33,7 +33,7 @@ class HBridgeFan : public Component, public fan::Fan {
   output::FloatOutput *pin_b_;
   output::FloatOutput *enable_{nullptr};
   output::BinaryOutput *oscillating_{nullptr};
-  int speed_count_{};
+  uint8_t speed_count_{};
   DecayMode decay_mode_{DECAY_MODE_SLOW};
   fan::FanTraits traits_;
   std::vector<const char *> preset_modes_{};

esphome/components/homeassistant/number/homeassistant_number.cpp

@@ -97,7 +97,7 @@ void HomeassistantNumber::control(float value) {
   entity_value.key = VALUE_KEY;
   // Stack buffer - no heap allocation; %g produces shortest representation
   char value_buf[16];
-  snprintf(value_buf, sizeof(value_buf), "%g", value);
+  buf_append_printf(value_buf, sizeof(value_buf), 0, "%g", value);
   entity_value.value = StringRef(value_buf);
 
   api::global_api_server->send_homeassistant_action(resp);

esphome/components/i2c/i2c_bus_esp_idf.cpp

@@ -119,7 +119,7 @@ void IDFI2CBus::dump_config() {
         if (s.second) {
           ESP_LOGCONFIG(TAG, "Found device at address 0x%02X", s.first);
         } else {
-          ESP_LOGE(TAG, "Unknown error at address 0x%02X", s.first);
+          ESP_LOGCONFIG(TAG, "Unknown error at address 0x%02X", s.first);
         }
       }
     }

esphome/components/i2s_audio/__init__.py

@@ -1,6 +1,11 @@
 from esphome import pins
 import esphome.codegen as cg
 from esphome.components.esp32 import (
+    add_idf_sdkconfig_option,
+    enable_ringbuf_in_iram,
+    get_esp32_variant,
+)
+from esphome.components.esp32.const import (
     VARIANT_ESP32,
     VARIANT_ESP32C3,
     VARIANT_ESP32C5,
@@ -10,8 +15,6 @@ from esphome.components.esp32 import (
     VARIANT_ESP32P4,
     VARIANT_ESP32S2,
     VARIANT_ESP32S3,
-    add_idf_sdkconfig_option,
-    get_esp32_variant,
 )
 import esphome.config_validation as cv
 from esphome.const import CONF_BITS_PER_SAMPLE, CONF_CHANNEL, CONF_ID, CONF_SAMPLE_RATE
@@ -278,6 +281,9 @@ async def to_code(config):
     # Helps avoid callbacks being skipped due to processor load
     add_idf_sdkconfig_option("CONFIG_I2S_ISR_IRAM_SAFE", True)
 
+    # Keep ring buffer functions in IRAM for audio performance
+    enable_ringbuf_in_iram()
+
     cg.add(var.set_lrclk_pin(config[CONF_I2S_LRCLK_PIN]))
     if CONF_I2S_BCLK_PIN in config:
         cg.add(var.set_bclk_pin(config[CONF_I2S_BCLK_PIN]))

esphome/components/kuntze/kuntze.cpp

@@ -11,7 +11,7 @@ static const char *const TAG = "kuntze";
 static const uint8_t CMD_READ_REG = 0x03;
 static const uint16_t REGISTER[] = {4136, 4160, 4680, 6000, 4688, 4728, 5832};
 
-// Maximum bytes to log for Modbus responses (2 registers = 4, plus count = 5)
+// Maximum bytes to log for Modbus responses (2 registers = 4 bytes, plus byte count = 5 bytes)
 static constexpr size_t KUNTZE_MAX_LOG_BYTES = 8;
 
 void Kuntze::on_modbus_data(const std::vector<uint8_t> &data) {

esphome/components/libretiny/preferences.cpp

@@ -18,16 +18,7 @@ static constexpr size_t KEY_BUFFER_SIZE = 12;
 
 struct NVSData {
   uint32_t key;
-  std::unique_ptr<uint8_t[]> data;
-  size_t len;
-
-  void set_data(const uint8_t *src, size_t size) {
-    if (!this->data || this->len != size) {
-      this->data = std::make_unique<uint8_t[]>(size);
-      this->len = size;
-    }
-    memcpy(this->data.get(), src, size);
-  }
+  SmallInlineBuffer<8> data;  // Most prefs fit in 8 bytes (covers fan, cover, select, etc.)
 };
 
 static std::vector<NVSData> s_pending_save;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
@@ -42,14 +33,14 @@ class LibreTinyPreferenceBackend : public ESPPreferenceBackend {
     // try find in pending saves and update that
     for (auto &obj : s_pending_save) {
       if (obj.key == this->key) {
-        obj.set_data(data, len);
+        obj.data.set(data, len);
         return true;
       }
     }
     NVSData save{};
     save.key = this->key;
-    save.set_data(data, len);
-    s_pending_save.emplace_back(std::move(save));
+    save.data.set(data, len);
+    s_pending_save.push_back(std::move(save));
     ESP_LOGVV(TAG, "s_pending_save: key: %" PRIu32 ", len: %zu", this->key, len);
     return true;
   }
@@ -58,11 +49,11 @@ class LibreTinyPreferenceBackend : public ESPPreferenceBackend {
     // try find in pending saves and load from that
     for (auto &obj : s_pending_save) {
       if (obj.key == this->key) {
-        if (obj.len != len) {
+        if (obj.data.size() != len) {
           // size mismatch
           return false;
         }
-        memcpy(data, obj.data.get(), len);
+        memcpy(data, obj.data.data(), len);
         return true;
       }
     }
@@ -126,11 +117,11 @@ class LibreTinyPreferences : public ESPPreferences {
       snprintf(key_str, sizeof(key_str), "%" PRIu32, save.key);
       ESP_LOGVV(TAG, "Checking if FDB data %s has changed", key_str);
       if (this->is_changed_(&this->db, save, key_str)) {
-        ESP_LOGV(TAG, "sync: key: %s, len: %zu", key_str, save.len);
-        fdb_blob_make(&this->blob, save.data.get(), save.len);
+        ESP_LOGV(TAG, "sync: key: %s, len: %zu", key_str, save.data.size());
+        fdb_blob_make(&this->blob, save.data.data(), save.data.size());
         fdb_err_t err = fdb_kv_set_blob(&this->db, key_str, &this->blob);
         if (err != FDB_NO_ERR) {
-          ESP_LOGV(TAG, "fdb_kv_set_blob('%s', len=%zu) failed: %d", key_str, save.len, err);
+          ESP_LOGV(TAG, "fdb_kv_set_blob('%s', len=%zu) failed: %d", key_str, save.data.size(), err);
           failed++;
           last_err = err;
           last_key = save.key;
@@ -138,7 +129,7 @@ class LibreTinyPreferences : public ESPPreferences {
         }
         written++;
       } else {
-        ESP_LOGD(TAG, "FDB data not changed; skipping %" PRIu32 "  len=%zu", save.key, save.len);
+        ESP_LOGD(TAG, "FDB data not changed; skipping %" PRIu32 "  len=%zu", save.key, save.data.size());
         cached++;
       }
       s_pending_save.erase(s_pending_save.begin() + i);
@@ -162,7 +153,7 @@ class LibreTinyPreferences : public ESPPreferences {
     }
 
     // Check size first - if different, data has changed
-    if (kv.value_len != to_save.len) {
+    if (kv.value_len != to_save.data.size()) {
       return true;
     }
 
@@ -176,7 +167,7 @@ class LibreTinyPreferences : public ESPPreferences {
     }
 
     // Compare the actual data
-    return memcmp(to_save.data.get(), stored_data.get(), kv.value_len) != 0;
+    return memcmp(to_save.data.data(), stored_data.get(), kv.value_len) != 0;
   }
 
   bool reset() override {

esphome/components/lightwaverf/lightwaverf.cpp

@@ -1,3 +1,4 @@
+#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
 #ifdef USE_ESP8266
@@ -44,13 +45,16 @@ void LightWaveRF::send_rx(const std::vector<uint8_t> &msg, uint8_t repeats, bool
 }
 
 void LightWaveRF::print_msg_(uint8_t *msg, uint8_t len) {
-  char buffer[65];
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_DEBUG
+  char buffer[65];  // max 10 entries * 6 chars + null
   ESP_LOGD(TAG, " Received code (len:%i): ", len);
 
+  size_t pos = 0;
   for (int i = 0; i < len; i++) {
-    sprintf(&buffer[i * 6], "0x%02x, ", msg[i]);
+    pos = buf_append_printf(buffer, sizeof(buffer), pos, "0x%02x, ", msg[i]);
   }
   ESP_LOGD(TAG, "[%s]", buffer);
+#endif
 }
 
 void LightWaveRF::dump_config() {

esphome/components/logger/logger_esp8266.cpp.bak

@@ -0,0 +1,51 @@
+#ifdef USE_ESP8266
+#include "logger.h"
+#include "esphome/core/log.h"
+
+namespace esphome::logger {
+
+static const char *const TAG = "logger";
+
+void Logger::pre_setup() {
+  if (this->baud_rate_ > 0) {
+    switch (this->uart_) {
+      case UART_SELECTION_UART0:
+      case UART_SELECTION_UART0_SWAP:
+        this->hw_serial_ = &Serial;
+        Serial.begin(this->baud_rate_);
+        if (this->uart_ == UART_SELECTION_UART0_SWAP) {
+          Serial.swap();
+        }
+        Serial.setDebugOutput(ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE);
+        break;
+      case UART_SELECTION_UART1:
+        this->hw_serial_ = &Serial1;
+        Serial1.begin(this->baud_rate_);
+        Serial1.setDebugOutput(ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE);
+        break;
+    }
+  } else {
+    uart_set_debug(UART_NO);
+  }
+
+  global_logger = this;
+
+  ESP_LOGI(TAG, "Log initialized");
+}
+
+void HOT Logger::write_msg_(const char *msg) { this->hw_serial_->println(msg); }
+
+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");
+    case UART_SELECTION_UART0_SWAP:
+    default:
+      return LOG_STR("UART0_SWAP");
+  }
+}
+
+}  // namespace esphome::logger
+#endif

esphome/components/logger/logger_host.cpp.bak

@@ -0,0 +1,22 @@
+#if defined(USE_HOST)
+#include "logger.h"
+
+namespace esphome::logger {
+
+void HOT Logger::write_msg_(const char *msg) {
+  time_t rawtime;
+  struct tm *timeinfo;
+  char buffer[80];
+
+  time(&rawtime);
+  timeinfo = localtime(&rawtime);
+  strftime(buffer, sizeof buffer, "[%H:%M:%S]", timeinfo);
+  fputs(buffer, stdout);
+  puts(msg);
+}
+
+void Logger::pre_setup() { global_logger = this; }
+
+}  // namespace esphome::logger
+
+#endif

esphome/components/logger/logger_libretiny.cpp.bak

@@ -0,0 +1,70 @@
+#ifdef USE_LIBRETINY
+#include "logger.h"
+
+namespace esphome::logger {
+
+static const char *const 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;
+        Serial0.begin(this->baud_rate_);
+        break;
+#endif
+#if LT_HW_UART1
+      case UART_SELECTION_UART1:
+        this->hw_serial_ = &Serial1;
+        Serial1.begin(this->baud_rate_);
+        break;
+#endif
+#if LT_HW_UART2
+      case UART_SELECTION_UART2:
+        this->hw_serial_ = &Serial2;
+        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;
+    }
+
+    // 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);
+    }
+  }
+
+  global_logger = this;
+  ESP_LOGI(TAG, "Log initialized");
+}
+
+void HOT Logger::write_msg_(const char *msg) { this->hw_serial_->println(msg); }
+
+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");
+  }
+}
+
+}  // namespace esphome::logger
+
+#endif  // USE_LIBRETINY

esphome/components/logger/logger_rp2040.cpp.bak

@@ -0,0 +1,48 @@
+#ifdef USE_RP2040
+#include "logger.h"
+#include "esphome/core/log.h"
+
+namespace esphome::logger {
+
+static const char *const TAG = "logger";
+
+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;
+    }
+  }
+  global_logger = this;
+  ESP_LOGI(TAG, "Log initialized");
+}
+
+void HOT Logger::write_msg_(const char *msg) { this->hw_serial_->println(msg); }
+
+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");
+  }
+}
+
+}  // namespace esphome::logger
+#endif  // USE_RP2040

esphome/components/logger/logger_zephyr.cpp.bak

@@ -0,0 +1,96 @@
+#ifdef USE_ZEPHYR
+
+#include "esphome/core/application.h"
+#include "esphome/core/log.h"
+#include "logger.h"
+
+#include <zephyr/device.h>
+#include <zephyr/drivers/uart.h>
+#include <zephyr/usb/usb_device.h>
+
+namespace esphome::logger {
+
+static const char *const TAG = "logger";
+
+#ifdef USE_LOGGER_USB_CDC
+void Logger::loop() {
+  if (this->uart_ != UART_SELECTION_USB_CDC || nullptr == this->uart_dev_) {
+    return;
+  }
+  static bool opened = false;
+  uint32_t dtr = 0;
+  uart_line_ctrl_get(this->uart_dev_, UART_LINE_CTRL_DTR, &dtr);
+
+  /* Poll if the DTR flag was set, optional */
+  if (opened == dtr) {
+    return;
+  }
+
+  if (!opened) {
+    App.schedule_dump_config();
+  }
+  opened = !opened;
+}
+#endif
+
+void Logger::pre_setup() {
+  if (this->baud_rate_ > 0) {
+    static const struct device *uart_dev = nullptr;
+    switch (this->uart_) {
+      case UART_SELECTION_UART0:
+        uart_dev = DEVICE_DT_GET_OR_NULL(DT_NODELABEL(uart0));
+        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:
+        uart_dev = DEVICE_DT_GET_OR_NULL(DT_NODELABEL(cdc_acm_uart0));
+        if (device_is_ready(uart_dev)) {
+          usb_enable(nullptr);
+        }
+        break;
+#endif
+    }
+    if (!device_is_ready(uart_dev)) {
+      ESP_LOGE(TAG, "%s is not ready.", LOG_STR_ARG(get_uart_selection_()));
+    } else {
+      this->uart_dev_ = uart_dev;
+    }
+  }
+  global_logger = this;
+  ESP_LOGI(TAG, "Log initialized");
+}
+
+void HOT Logger::write_msg_(const char *msg) {
+#ifdef CONFIG_PRINTK
+  printk("%s\n", msg);
+#endif
+  if (nullptr == this->uart_dev_) {
+    return;
+  }
+  while (*msg) {
+    uart_poll_out(this->uart_dev_, *msg);
+    ++msg;
+  }
+  uart_poll_out(this->uart_dev_, '\n');
+}
+
+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");
+  }
+}
+
+}  // namespace esphome::logger
+
+#endif

esphome/components/mapping/mapping.h

@@ -2,6 +2,7 @@
 
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
+#include <cinttypes>
 #include <map>
 #include <string>
 
@@ -43,8 +44,17 @@ template<typename K, typename V> class Mapping {
       esph_log_e(TAG, "Key '%p' not found in mapping", key);
     } else if constexpr (std::is_same_v<K, std::string>) {
       esph_log_e(TAG, "Key '%s' not found in mapping", key.c_str());
+    } else if constexpr (std::is_integral_v<K>) {
+      char buf[24];  // enough for 64-bit integer
+      if constexpr (std::is_unsigned_v<K>) {
+        buf_append_printf(buf, sizeof(buf), 0, "%" PRIu64, static_cast<uint64_t>(key));
+      } else {
+        buf_append_printf(buf, sizeof(buf), 0, "%" PRId64, static_cast<int64_t>(key));
+      }
+      esph_log_e(TAG, "Key '%s' not found in mapping", buf);
     } else {
-      esph_log_e(TAG, "Key '%s' not found in mapping", to_string(key).c_str());
+      // All supported key types are handled above - this should never be reached
+      static_assert(sizeof(K) == 0, "Unsupported key type for Mapping error logging");
     }
     return {};
   }

esphome/components/max6956/max6956.cpp

@@ -162,7 +162,7 @@ void MAX6956GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this-
 bool MAX6956GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void MAX6956GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
 size_t MAX6956GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return snprintf(buffer, len, "%u via Max6956", this->pin_);
+  return buf_append_printf(buffer, len, 0, "%u via Max6956", this->pin_);
 }
 
 }  // namespace max6956

esphome/components/mcp23016/mcp23016.cpp

@@ -56,7 +56,7 @@ void MCP23016::pin_mode(uint8_t pin, gpio::Flags flags) {
     this->update_reg_(pin, false, iodir);
   }
 }
-float MCP23016::get_setup_priority() const { return setup_priority::HARDWARE; }
+float MCP23016::get_setup_priority() const { return setup_priority::IO; }
 bool MCP23016::read_reg_(uint8_t reg, uint8_t *value) {
   if (this->is_failed())
     return false;
@@ -100,7 +100,7 @@ void MCP23016GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this
 bool MCP23016GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void MCP23016GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
 size_t MCP23016GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return snprintf(buffer, len, "%u via MCP23016", this->pin_);
+  return buf_append_printf(buffer, len, 0, "%u via MCP23016", this->pin_);
 }
 
 }  // namespace mcp23016

esphome/components/mcp23xxx_base/mcp23xxx_base.cpp

@@ -17,7 +17,7 @@ template<uint8_t N> void MCP23XXXGPIOPin<N>::digital_write(bool value) {
   this->parent_->digital_write(this->pin_, value != this->inverted_);
 }
 template<uint8_t N> size_t MCP23XXXGPIOPin<N>::dump_summary(char *buffer, size_t len) const {
-  return snprintf(buffer, len, "%u via MCP23XXX", this->pin_);
+  return buf_append_printf(buffer, len, 0, "%u via MCP23XXX", this->pin_);
 }
 
 template class MCP23XXXGPIOPin<8>;

esphome/components/micro_wake_word/__init__.py

@@ -448,6 +448,9 @@ async def to_code(config):
     # The inference task queues detection events that need immediate processing
     socket.require_wake_loop_threadsafe()
 
+    # Keep ring buffer functions in IRAM for audio performance
+    esp32.enable_ringbuf_in_iram()
+
     mic_source = await microphone.microphone_source_to_code(config[CONF_MICROPHONE])
     cg.add(var.set_microphone_source(mic_source))
 

esphome/components/modbus_controller/modbus_controller.h

@@ -271,24 +271,31 @@ class ServerRegister {
 
   // Formats a raw value into a string representation based on the value type for debugging
   std::string format_value(int64_t value) const {
+    // max 48: float with %.1f can be up to 42 chars (3.4e38 → 38 integer digits + decimal + 1 digit + sign + null)
+    // int64_t max is 20 chars + sign + null = 22, so 48 covers both
+    char buf[48];
     switch (this->value_type) {
       case SensorValueType::U_WORD:
       case SensorValueType::U_DWORD:
       case SensorValueType::U_DWORD_R:
       case SensorValueType::U_QWORD:
       case SensorValueType::U_QWORD_R:
-        return std::to_string(static_cast<uint64_t>(value));
+        buf_append_printf(buf, sizeof(buf), 0, "%" PRIu64, static_cast<uint64_t>(value));
+        return buf;
       case SensorValueType::S_WORD:
       case SensorValueType::S_DWORD:
       case SensorValueType::S_DWORD_R:
       case SensorValueType::S_QWORD:
       case SensorValueType::S_QWORD_R:
-        return std::to_string(value);
+        buf_append_printf(buf, sizeof(buf), 0, "%" PRId64, value);
+        return buf;
       case SensorValueType::FP32_R:
       case SensorValueType::FP32:
-        return str_sprintf("%.1f", bit_cast<float>(static_cast<uint32_t>(value)));
+        buf_append_printf(buf, sizeof(buf), 0, "%.1f", bit_cast<float>(static_cast<uint32_t>(value)));
+        return buf;
       default:
-        return std::to_string(value);
+        buf_append_printf(buf, sizeof(buf), 0, "%" PRId64, value);
+        return buf;
     }
   }
 

esphome/components/modbus_controller/text_sensor/modbus_textsensor.cpp

@@ -16,12 +16,20 @@ void ModbusTextSensor::parse_and_publish(const std::vector<uint8_t> &data) {
   while ((items_left > 0) && index < data.size()) {
     uint8_t b = data[index];
     switch (this->encode_) {
-      case RawEncoding::HEXBYTES:
-        output_str += str_snprintf("%02x", 2, b);
+      case RawEncoding::HEXBYTES: {
+        // max 3: 2 hex digits + null
+        char hex_buf[3];
+        snprintf(hex_buf, sizeof(hex_buf), "%02x", b);
+        output_str += hex_buf;
         break;
-      case RawEncoding::COMMA:
-        output_str += str_sprintf(index != this->offset ? ",%d" : "%d", b);
+      }
+      case RawEncoding::COMMA: {
+        // max 5: optional ','(1) + uint8(3) + null, for both ",%d" and "%d"
+        char dec_buf[5];
+        snprintf(dec_buf, sizeof(dec_buf), index != this->offset ? ",%d" : "%d", b);
+        output_str += dec_buf;
         break;
+      }
       case RawEncoding::ANSI:
         if (b < 0x20)
           break;

esphome/components/mpr121/mpr121.cpp

@@ -154,7 +154,7 @@ void MPR121GPIOPin::digital_write(bool value) {
 }
 
 size_t MPR121GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return snprintf(buffer, len, "ELE%u on MPR121", this->pin_);
+  return buf_append_printf(buffer, len, 0, "ELE%u on MPR121", this->pin_);
 }
 
 }  // namespace mpr121

esphome/components/mqtt/custom_mqtt_device.cpp

@@ -18,7 +18,7 @@ bool CustomMQTTDevice::publish(const std::string &topic, float value, int8_t num
 }
 bool CustomMQTTDevice::publish(const std::string &topic, int value) {
   char buffer[24];
-  int len = snprintf(buffer, sizeof(buffer), "%d", value);
+  size_t len = buf_append_printf(buffer, sizeof(buffer), 0, "%d", value);
   return global_mqtt_client->publish(topic, buffer, len);
 }
 bool CustomMQTTDevice::publish_json(const std::string &topic, const json::json_build_t &f, uint8_t qos, bool retain) {

esphome/components/mqtt/mqtt_client.cpp

@@ -91,7 +91,17 @@ void MQTTClientComponent::send_device_info_() {
         uint8_t index = 0;
         for (auto &ip : network::get_ip_addresses()) {
           if (ip.is_set()) {
-            root["ip" + (index == 0 ? "" : esphome::to_string(index))] = ip.str();
+            char key[8];  // "ip" + up to 3 digits + null
+            char ip_buf[network::IP_ADDRESS_BUFFER_SIZE];
+            if (index == 0) {
+              key[0] = 'i';
+              key[1] = 'p';
+              key[2] = '\0';
+            } else {
+              buf_append_printf(key, sizeof(key), 0, "ip%u", index);
+            }
+            ip.str_to(ip_buf);
+            root[key] = ip_buf;
             index++;
           }
         }
@@ -635,7 +645,8 @@ void MQTTClientComponent::set_log_message_template(MQTTMessage &&message) { this
 const MQTTDiscoveryInfo &MQTTClientComponent::get_discovery_info() const { return this->discovery_info_; }
 void MQTTClientComponent::set_topic_prefix(const std::string &topic_prefix, const std::string &check_topic_prefix) {
   if (App.is_name_add_mac_suffix_enabled() && (topic_prefix == check_topic_prefix)) {
-    this->topic_prefix_ = str_sanitize(App.get_name());
+    char buf[ESPHOME_DEVICE_NAME_MAX_LEN + 1];
+    this->topic_prefix_ = str_sanitize_to(buf, App.get_name().c_str());
   } else {
     this->topic_prefix_ = topic_prefix;
   }

esphome/components/mqtt/mqtt_component.cpp

@@ -48,7 +48,8 @@ void MQTTComponent::set_subscribe_qos(uint8_t qos) { this->subscribe_qos_ = qos;
 void MQTTComponent::set_retain(bool retain) { this->retain_ = retain; }
 
 std::string MQTTComponent::get_discovery_topic_(const MQTTDiscoveryInfo &discovery_info) const {
-  std::string sanitized_name = str_sanitize(App.get_name());
+  char sanitized_name[ESPHOME_DEVICE_NAME_MAX_LEN + 1];
+  str_sanitize_to(sanitized_name, App.get_name().c_str());
   const char *comp_type = this->component_type();
   char object_id_buf[OBJECT_ID_MAX_LEN];
   StringRef object_id = this->get_default_object_id_to_(object_id_buf);
@@ -60,7 +61,7 @@ std::string MQTTComponent::get_discovery_topic_(const MQTTDiscoveryInfo &discove
   p = append_char(p, '/');
   p = append_str(p, comp_type, strlen(comp_type));
   p = append_char(p, '/');
-  p = append_str(p, sanitized_name.data(), sanitized_name.size());
+  p = append_str(p, sanitized_name, strlen(sanitized_name));
   p = append_char(p, '/');
   p = append_str(p, object_id.c_str(), object_id.size());
   p = append_str(p, "/config", 7);
@@ -189,27 +190,37 @@ bool MQTTComponent::send_discovery_() {
         StringRef object_id = this->get_default_object_id_to_(object_id_buf);
         if (discovery_info.unique_id_generator == MQTT_MAC_ADDRESS_UNIQUE_ID_GENERATOR) {
           char friendly_name_hash[9];
-          snprintf(friendly_name_hash, sizeof(friendly_name_hash), "%08" PRIx32, fnv1_hash(this->friendly_name_()));
+          buf_append_printf(friendly_name_hash, sizeof(friendly_name_hash), 0, "%08" PRIx32,
+                            fnv1_hash(this->friendly_name_()));
           // Format: mac-component_type-hash (e.g. "aabbccddeeff-sensor-12345678")
           // MAC (12) + "-" (1) + domain (max 20) + "-" (1) + hash (8) + null (1) = 43
           char unique_id[MAC_ADDRESS_BUFFER_SIZE + ESPHOME_DOMAIN_MAX_LEN + 11];
           char mac_buf[MAC_ADDRESS_BUFFER_SIZE];
           get_mac_address_into_buffer(mac_buf);
-          snprintf(unique_id, sizeof(unique_id), "%s-%s-%s", mac_buf, this->component_type(), friendly_name_hash);
+          buf_append_printf(unique_id, sizeof(unique_id), 0, "%s-%s-%s", mac_buf, this->component_type(),
+                            friendly_name_hash);
           root[MQTT_UNIQUE_ID] = unique_id;
         } else {
           // default to almost-unique ID. It's a hack but the only way to get that
           // gorgeous device registry view.
-          root[MQTT_UNIQUE_ID] = "ESP" + std::string(this->component_type()) + object_id.c_str();
+          // "ESP" (3) + component_type (max 20) + object_id (max 128) + null
+          char unique_id_buf[3 + MQTT_COMPONENT_TYPE_MAX_LEN + OBJECT_ID_MAX_LEN + 1];
+          buf_append_printf(unique_id_buf, sizeof(unique_id_buf), 0, "ESP%s%s", this->component_type(),
+                            object_id.c_str());
+          root[MQTT_UNIQUE_ID] = unique_id_buf;
         }
 
         const std::string &node_name = App.get_name();
-        if (discovery_info.object_id_generator == MQTT_DEVICE_NAME_OBJECT_ID_GENERATOR)
-          root[MQTT_OBJECT_ID] = node_name + "_" + object_id.c_str();
+        if (discovery_info.object_id_generator == MQTT_DEVICE_NAME_OBJECT_ID_GENERATOR) {
+          // node_name (max 31) + "_" (1) + object_id (max 128) + null
+          char object_id_full[ESPHOME_DEVICE_NAME_MAX_LEN + 1 + OBJECT_ID_MAX_LEN + 1];
+          buf_append_printf(object_id_full, sizeof(object_id_full), 0, "%s_%s", node_name.c_str(), object_id.c_str());
+          root[MQTT_OBJECT_ID] = object_id_full;
+        }
 
         const std::string &friendly_name_ref = App.get_friendly_name();
         const std::string &node_friendly_name = friendly_name_ref.empty() ? node_name : friendly_name_ref;
-        std::string node_area = App.get_area();
+        const char *node_area = App.get_area();
 
         JsonObject device_info = root[MQTT_DEVICE].to<JsonObject>();
         char mac[MAC_ADDRESS_BUFFER_SIZE];
@@ -220,18 +231,29 @@ bool MQTTComponent::send_discovery_() {
         device_info[MQTT_DEVICE_SW_VERSION] = ESPHOME_PROJECT_VERSION " (ESPHome " ESPHOME_VERSION ")";
         const char *model = std::strchr(ESPHOME_PROJECT_NAME, '.');
         device_info[MQTT_DEVICE_MODEL] = model == nullptr ? ESPHOME_BOARD : model + 1;
-        device_info[MQTT_DEVICE_MANUFACTURER] =
-            model == nullptr ? ESPHOME_PROJECT_NAME : std::string(ESPHOME_PROJECT_NAME, model - ESPHOME_PROJECT_NAME);
+        if (model == nullptr) {
+          device_info[MQTT_DEVICE_MANUFACTURER] = ESPHOME_PROJECT_NAME;
+        } else {
+          // Extract manufacturer (part before '.') using stack buffer to avoid heap allocation
+          // memcpy is used instead of strncpy since we know the exact length and strncpy
+          // would still require manual null-termination
+          char manufacturer[sizeof(ESPHOME_PROJECT_NAME)];
+          size_t len = model - ESPHOME_PROJECT_NAME;
+          memcpy(manufacturer, ESPHOME_PROJECT_NAME, len);
+          manufacturer[len] = '\0';
+          device_info[MQTT_DEVICE_MANUFACTURER] = manufacturer;
+        }
 #else
         static const char ver_fmt[] PROGMEM = ESPHOME_VERSION " (config hash 0x%08" PRIx32 ")";
+        // Buffer sized for format string expansion: ~4 bytes net growth from format specifier to 8 hex digits, plus
+        // safety margin
+        char version_buf[sizeof(ver_fmt) + 8];
 #ifdef USE_ESP8266
-        char fmt_buf[sizeof(ver_fmt)];
-        strcpy_P(fmt_buf, ver_fmt);
-        const char *fmt = fmt_buf;
+        snprintf_P(version_buf, sizeof(version_buf), ver_fmt, App.get_config_hash());
 #else
-        const char *fmt = ver_fmt;
+        snprintf(version_buf, sizeof(version_buf), ver_fmt, App.get_config_hash());
 #endif
-        device_info[MQTT_DEVICE_SW_VERSION] = str_sprintf(fmt, App.get_config_hash());
+        device_info[MQTT_DEVICE_SW_VERSION] = version_buf;
         device_info[MQTT_DEVICE_MODEL] = ESPHOME_BOARD;
 #if defined(USE_ESP8266) || defined(USE_ESP32)
         device_info[MQTT_DEVICE_MANUFACTURER] = "Espressif";
@@ -245,7 +267,7 @@ bool MQTTComponent::send_discovery_() {
         device_info[MQTT_DEVICE_MANUFACTURER] = "Host";
 #endif
 #endif
-        if (!node_area.empty()) {
+        if (node_area[0] != '\0') {
           device_info[MQTT_DEVICE_SUGGESTED_AREA] = node_area;
         }
 

esphome/components/mqtt/mqtt_fan.cpp

@@ -175,7 +175,7 @@ bool MQTTFanComponent::publish_state() {
   auto traits = this->state_->get_traits();
   if (traits.supports_speed()) {
     char buf[12];
-    int len = snprintf(buf, sizeof(buf), "%d", this->state_->speed);
+    size_t len = buf_append_printf(buf, sizeof(buf), 0, "%d", this->state_->speed);
     bool success = this->publish(this->get_speed_level_state_topic(), buf, len);
     failed = failed || !success;
   }

esphome/components/mqtt/mqtt_number.cpp

@@ -75,7 +75,7 @@ bool MQTTNumberComponent::send_initial_state() {
 }
 bool MQTTNumberComponent::publish_state(float value) {
   char buffer[64];
-  snprintf(buffer, sizeof(buffer), "%f", value);
+  buf_append_printf(buffer, sizeof(buffer), 0, "%f", value);
   return this->publish(this->get_state_topic_(), buffer);
 }
 

esphome/components/network/ip_address.h

@@ -43,6 +43,14 @@ namespace network {
 /// Buffer size for IP address string (IPv6 max: 39 chars + null)
 static constexpr size_t IP_ADDRESS_BUFFER_SIZE = 40;
 
+/// Lowercase hex digits in IP address string (A-F -> a-f for IPv6 per RFC 5952)
+inline void lowercase_ip_str(char *buf) {
+  for (char *p = buf; *p; ++p) {
+    if (*p >= 'A' && *p <= 'F')
+      *p += 32;
+  }
+}
+
 struct IPAddress {
  public:
 #ifdef USE_HOST
@@ -52,10 +60,15 @@ struct IPAddress {
   }
   IPAddress(const std::string &in_address) { inet_aton(in_address.c_str(), &ip_addr_); }
   IPAddress(const ip_addr_t *other_ip) { ip_addr_ = *other_ip; }
-  std::string str() const { return str_lower_case(inet_ntoa(ip_addr_)); }
+  std::string str() const {
+    char buf[IP_ADDRESS_BUFFER_SIZE];
+    this->str_to(buf);
+    return buf;
+  }
   /// Write IP address to buffer. Buffer must be at least IP_ADDRESS_BUFFER_SIZE bytes.
   char *str_to(char *buf) const {
-    return const_cast<char *>(inet_ntop(AF_INET, &ip_addr_, buf, IP_ADDRESS_BUFFER_SIZE));
+    inet_ntop(AF_INET, &ip_addr_, buf, IP_ADDRESS_BUFFER_SIZE);
+    return buf;  // IPv4 only, no hex letters to lowercase
   }
 #else
   IPAddress() { ip_addr_set_zero(&ip_addr_); }
@@ -134,9 +147,18 @@ struct IPAddress {
   bool is_ip4() const { return IP_IS_V4(&ip_addr_); }
   bool is_ip6() const { return IP_IS_V6(&ip_addr_); }
   bool is_multicast() const { return ip_addr_ismulticast(&ip_addr_); }
-  std::string str() const { return str_lower_case(ipaddr_ntoa(&ip_addr_)); }
+  std::string str() const {
+    char buf[IP_ADDRESS_BUFFER_SIZE];
+    this->str_to(buf);
+    return buf;
+  }
   /// Write IP address to buffer. Buffer must be at least IP_ADDRESS_BUFFER_SIZE bytes.
-  char *str_to(char *buf) const { return ipaddr_ntoa_r(&ip_addr_, buf, IP_ADDRESS_BUFFER_SIZE); }
+  /// Output is lowercased per RFC 5952 (IPv6 hex digits a-f).
+  char *str_to(char *buf) const {
+    ipaddr_ntoa_r(&ip_addr_, buf, IP_ADDRESS_BUFFER_SIZE);
+    lowercase_ip_str(buf);
+    return buf;
+  }
   bool operator==(const IPAddress &other) const { return ip_addr_cmp(&ip_addr_, &other.ip_addr_); }
   bool operator!=(const IPAddress &other) const { return !ip_addr_cmp(&ip_addr_, &other.ip_addr_); }
   IPAddress &operator+=(uint8_t increase) {

esphome/components/nextion/nextion.cpp

@@ -1,6 +1,7 @@
 #include "nextion.h"
 #include <cinttypes>
 #include "esphome/core/application.h"
+#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 #include "esphome/core/util.h"
 
@@ -1283,8 +1284,9 @@ void Nextion::check_pending_waveform_() {
   size_t buffer_to_send = component->get_wave_buffer_size() < 255 ? component->get_wave_buffer_size()
                                                                   : 255;  // ADDT command can only send 255
 
-  std::string command = "addt " + to_string(component->get_component_id()) + "," +
-                        to_string(component->get_wave_channel_id()) + "," + to_string(buffer_to_send);
+  char command[24];  // "addt " + uint8 + "," + uint8 + "," + uint8 + null = max 17 chars
+  buf_append_printf(command, sizeof(command), 0, "addt %u,%u,%zu", component->get_component_id(),
+                    component->get_wave_channel_id(), buffer_to_send);
   if (!this->send_command_(command)) {
     delete nb;  // NOLINT(cppcoreguidelines-owning-memory)
     this->waveform_queue_.pop_front();

esphome/components/nextion/nextion_upload_arduino.cpp

@@ -34,7 +34,7 @@ int Nextion::upload_by_chunks_(HTTPClient &http_client, uint32_t &range_start) {
   }
 
   char range_header[32];
-  sprintf(range_header, "bytes=%" PRIu32 "-%" PRIu32, range_start, range_end);
+  buf_append_printf(range_header, sizeof(range_header), 0, "bytes=%" PRIu32 "-%" PRIu32, range_start, range_end);
   ESP_LOGV(TAG, "Range: %s", range_header);
   http_client.addHeader("Range", range_header);
   int code = http_client.GET();

esphome/components/nextion/nextion_upload_esp32.cpp

@@ -36,7 +36,7 @@ int Nextion::upload_by_chunks_(esp_http_client_handle_t http_client, uint32_t &r
   }
 
   char range_header[32];
-  sprintf(range_header, "bytes=%" PRIu32 "-%" PRIu32, range_start, range_end);
+  buf_append_printf(range_header, sizeof(range_header), 0, "bytes=%" PRIu32 "-%" PRIu32, range_start, range_end);
   ESP_LOGV(TAG, "Range: %s", range_header);
   esp_http_client_set_header(http_client, "Range", range_header);
   ESP_LOGV(TAG, "Open HTTP");

esphome/components/pca6416a/pca6416a.cpp

@@ -181,7 +181,7 @@ void PCA6416AGPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this
 bool PCA6416AGPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void PCA6416AGPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
 size_t PCA6416AGPIOPin::dump_summary(char *buffer, size_t len) const {
-  return snprintf(buffer, len, "%u via PCA6416A", this->pin_);
+  return buf_append_printf(buffer, len, 0, "%u via PCA6416A", this->pin_);
 }
 
 }  // namespace pca6416a

esphome/components/pca9554/pca9554.cpp

@@ -130,7 +130,7 @@ void PCA9554GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this-
 bool PCA9554GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void PCA9554GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
 size_t PCA9554GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return snprintf(buffer, len, "%u via PCA9554", this->pin_);
+  return buf_append_printf(buffer, len, 0, "%u via PCA9554", this->pin_);
 }
 
 }  // namespace pca9554

esphome/components/pcf8574/pcf8574.cpp

@@ -107,7 +107,7 @@ void PCF8574GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this-
 bool PCF8574GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void PCF8574GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
 size_t PCF8574GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return snprintf(buffer, len, "%u via PCF8574", this->pin_);
+  return buf_append_printf(buffer, len, 0, "%u via PCF8574", this->pin_);
 }
 
 }  // namespace pcf8574

esphome/components/pi4ioe5v6408/pi4ioe5v6408.cpp

@@ -165,7 +165,7 @@ void PI4IOE5V6408GPIOPin::digital_write(bool value) {
   this->parent_->digital_write(this->pin_, value != this->inverted_);
 }
 size_t PI4IOE5V6408GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return snprintf(buffer, len, "%u via PI4IOE5V6408", this->pin_);
+  return buf_append_printf(buffer, len, 0, "%u via PI4IOE5V6408", this->pin_);
 }
 
 }  // namespace pi4ioe5v6408

esphome/components/pipsolar/output/pipsolar_output.cpp

@@ -9,11 +9,11 @@ static const char *const TAG = "pipsolar.output";
 
 void PipsolarOutput::write_state(float state) {
   char tmp[10];
-  sprintf(tmp, this->set_command_.c_str(), state);
+  snprintf(tmp, sizeof(tmp), this->set_command_, state);
 
   if (std::find(this->possible_values_.begin(), this->possible_values_.end(), state) != this->possible_values_.end()) {
     ESP_LOGD(TAG, "Will write: %s out of value %f / %02.0f", tmp, state, state);
-    this->parent_->queue_command(std::string(tmp));
+    this->parent_->queue_command(tmp);
   } else {
     ESP_LOGD(TAG, "Will not write: %s as it is not in list of allowed values", tmp);
   }

esphome/components/pipsolar/output/pipsolar_output.h

@@ -15,13 +15,15 @@ class PipsolarOutput : public output::FloatOutput {
  public:
   PipsolarOutput() {}
   void set_parent(Pipsolar *parent) { this->parent_ = parent; }
-  void set_set_command(const std::string &command) { this->set_command_ = command; };
+  void set_set_command(const char *command) { this->set_command_ = command; }
+  /// Prevent accidental use of std::string which would dangle
+  void set_set_command(const std::string &command) = delete;
   void set_possible_values(std::vector<float> possible_values) { this->possible_values_ = std::move(possible_values); }
-  void set_value(float value) { this->write_state(value); };
+  void set_value(float value) { this->write_state(value); }
 
  protected:
   void write_state(float state) override;
-  std::string set_command_;
+  const char *set_command_{nullptr};
   Pipsolar *parent_;
   std::vector<float> possible_values_;
 };

esphome/components/pipsolar/pipsolar.cpp

@@ -45,20 +45,20 @@ void Pipsolar::loop() {
         } else {
           ESP_LOGD(TAG, "command not successful");
         }
-        this->command_queue_[this->command_queue_position_] = std::string("");
+        this->command_queue_[this->command_queue_position_].clear();
         this->command_queue_position_ = (command_queue_position_ + 1) % COMMAND_QUEUE_LENGTH;
         this->state_ = STATE_IDLE;
       } else {
         // crc failed
         // no log message necessary, check_incoming_crc_() logs
-        this->command_queue_[this->command_queue_position_] = std::string("");
+        this->command_queue_[this->command_queue_position_].clear();
         this->command_queue_position_ = (command_queue_position_ + 1) % COMMAND_QUEUE_LENGTH;
         this->state_ = STATE_IDLE;
       }
     } else {
       ESP_LOGD(TAG, "command %s response length not OK: with length %zu",
                this->command_queue_[this->command_queue_position_].c_str(), this->read_pos_);
-      this->command_queue_[this->command_queue_position_] = std::string("");
+      this->command_queue_[this->command_queue_position_].clear();
       this->command_queue_position_ = (command_queue_position_ + 1) % COMMAND_QUEUE_LENGTH;
       this->state_ = STATE_IDLE;
     }
@@ -127,7 +127,7 @@ void Pipsolar::loop() {
       const char *command = this->command_queue_[this->command_queue_position_].c_str();
       this->command_start_millis_ = millis();
       ESP_LOGD(TAG, "command %s timeout", command);
-      this->command_queue_[this->command_queue_position_] = std::string("");
+      this->command_queue_[this->command_queue_position_].clear();
       this->command_queue_position_ = (command_queue_position_ + 1) % COMMAND_QUEUE_LENGTH;
       this->state_ = STATE_IDLE;
       return;
@@ -722,7 +722,7 @@ void Pipsolar::publish_binary_sensor_(esphome::optional<bool> b, binary_sensor::
   }
 }
 
-esphome::optional<bool> Pipsolar::get_bit_(std::string bits, uint8_t bit_pos) {
+esphome::optional<bool> Pipsolar::get_bit_(const std::string &bits, uint8_t bit_pos) {
   if (bit_pos >= bits.length()) {
     return {};
   }

esphome/components/pipsolar/pipsolar.h

@@ -224,7 +224,7 @@ class Pipsolar : public uart::UARTDevice, public PollingComponent {
 
   void publish_binary_sensor_(esphome::optional<bool> b, binary_sensor::BinarySensor *sensor);
 
-  esphome::optional<bool> get_bit_(std::string bits, uint8_t bit_pos);
+  esphome::optional<bool> get_bit_(const std::string &bits, uint8_t bit_pos);
 
   std::string command_queue_[COMMAND_QUEUE_LENGTH];
   uint8_t command_queue_position_ = 0;

esphome/components/pipsolar/switch/pipsolar_switch.cpp

@@ -9,14 +9,9 @@ static const char *const TAG = "pipsolar.switch";
 
 void PipsolarSwitch::dump_config() { LOG_SWITCH("", "Pipsolar Switch", this); }
 void PipsolarSwitch::write_state(bool state) {
-  if (state) {
-    if (!this->on_command_.empty()) {
-      this->parent_->queue_command(this->on_command_);
-    }
-  } else {
-    if (!this->off_command_.empty()) {
-      this->parent_->queue_command(this->off_command_);
-    }
+  const char *command = state ? this->on_command_ : this->off_command_;
+  if (command != nullptr) {
+    this->parent_->queue_command(command);
   }
 }
 

esphome/components/pipsolar/switch/pipsolar_switch.h

@@ -9,15 +9,18 @@ namespace pipsolar {
 class Pipsolar;
 class PipsolarSwitch : public switch_::Switch, public Component {
  public:
-  void set_parent(Pipsolar *parent) { this->parent_ = parent; };
-  void set_on_command(const std::string &command) { this->on_command_ = command; };
-  void set_off_command(const std::string &command) { this->off_command_ = command; };
+  void set_parent(Pipsolar *parent) { this->parent_ = parent; }
+  void set_on_command(const char *command) { this->on_command_ = command; }
+  void set_off_command(const char *command) { this->off_command_ = command; }
+  /// Prevent accidental use of std::string which would dangle
+  void set_on_command(const std::string &command) = delete;
+  void set_off_command(const std::string &command) = delete;
   void dump_config() override;
 
  protected:
   void write_state(bool state) override;
-  std::string on_command_;
-  std::string off_command_;
+  const char *on_command_{nullptr};
+  const char *off_command_{nullptr};
   Pipsolar *parent_;
 };
 

esphome/components/rc522_spi/rc522_spi.cpp

@@ -1,4 +1,5 @@
 #include "rc522_spi.h"
+#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
 // Based on:
@@ -70,7 +71,7 @@ void RC522Spi::pcd_read_register(PcdRegister reg,  ///< The register to read fro
     index++;
 
 #ifdef ESPHOME_LOG_HAS_VERY_VERBOSE
-    sprintf(cstrb, " %x", values[0]);
+    buf_append_printf(cstrb, sizeof(cstrb), 0, " %x", values[0]);
     buf.append(cstrb);
 #endif
   }
@@ -78,7 +79,7 @@ void RC522Spi::pcd_read_register(PcdRegister reg,  ///< The register to read fro
     values[index] = transfer_byte(address);  // Read value and tell that we want to read the same address again.
 
 #ifdef ESPHOME_LOG_HAS_VERY_VERBOSE
-    sprintf(cstrb, " %x", values[index]);
+    buf_append_printf(cstrb, sizeof(cstrb), 0, " %x", values[index]);
     buf.append(cstrb);
 #endif
 
@@ -88,7 +89,7 @@ void RC522Spi::pcd_read_register(PcdRegister reg,  ///< The register to read fro
 
 #ifdef ESPHOME_LOG_HAS_VERY_VERBOSE
   buf = buf + " ";
-  sprintf(cstrb, "%x", values[index]);
+  buf_append_printf(cstrb, sizeof(cstrb), 0, "%x", values[index]);
   buf.append(cstrb);
 
   ESP_LOGVV(TAG, "read_register_array_(%x, %d, , %d) -> %s", reg, count, rx_align, buf.c_str());
@@ -127,7 +128,7 @@ void RC522Spi::pcd_write_register(PcdRegister reg,  ///< The register to write t
     transfer_byte(values[index]);
 
 #ifdef ESPHOME_LOG_HAS_VERY_VERBOSE
-    sprintf(cstrb, " %x", values[index]);
+    buf_append_printf(cstrb, sizeof(cstrb), 0, " %x", values[index]);
     buf.append(cstrb);
 #endif
   }

esphome/components/rf_bridge/rf_bridge.cpp

@@ -1,6 +1,7 @@
 #include "rf_bridge.h"
-#include "esphome/core/log.h"
 #include "esphome/core/application.h"
+#include "esphome/core/helpers.h"
+#include "esphome/core/log.h"
 #include <cinttypes>
 #include <cstring>
 
@@ -72,9 +73,9 @@ bool RFBridgeComponent::parse_bridge_byte_(uint8_t byte) {
 
       data.length = raw[2];
       data.protocol = raw[3];
-      char next_byte[3];
+      char next_byte[3];  // 2 hex chars + null
       for (uint8_t i = 0; i < data.length - 1; i++) {
-        sprintf(next_byte, "%02X", raw[4 + i]);
+        buf_append_printf(next_byte, sizeof(next_byte), 0, "%02X", raw[4 + i]);
         data.code += next_byte;
       }
 
@@ -90,10 +91,10 @@ bool RFBridgeComponent::parse_bridge_byte_(uint8_t byte) {
 
       uint8_t buckets = raw[2] << 1;
       std::string str;
-      char next_byte[3];
+      char next_byte[3];  // 2 hex chars + null
 
       for (uint32_t i = 0; i <= at; i++) {
-        sprintf(next_byte, "%02X", raw[i]);
+        buf_append_printf(next_byte, sizeof(next_byte), 0, "%02X", raw[i]);
         str += next_byte;
         if ((i > 3) && buckets) {
           buckets--;

esphome/components/select/__init__.py

@@ -33,7 +33,7 @@ SelectPtr = Select.operator("ptr")
 # Triggers
 SelectStateTrigger = select_ns.class_(
     "SelectStateTrigger",
-    automation.Trigger.template(cg.std_string, cg.size_t),
+    automation.Trigger.template(cg.StringRef, cg.size_t),
 )
 
 # Actions
@@ -100,7 +100,7 @@ async def setup_select_core_(var, config, *, options: list[str]):
     for conf in config.get(CONF_ON_VALUE, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
         await automation.build_automation(
-            trigger, [(cg.std_string, "x"), (cg.size_t, "i")], conf
+            trigger, [(cg.StringRef, "x"), (cg.size_t, "i")], conf
         )
 
     if (mqtt_id := config.get(CONF_MQTT_ID)) is not None:

esphome/components/select/automation.h

@@ -6,11 +6,11 @@
 
 namespace esphome::select {
 
-class SelectStateTrigger : public Trigger<std::string, size_t> {
+class SelectStateTrigger : public Trigger<StringRef, size_t> {
  public:
   explicit SelectStateTrigger(Select *parent) : parent_(parent) {
     parent->add_on_state_callback(
-        [this](size_t index) { this->trigger(std::string(this->parent_->option_at(index)), index); });
+        [this](size_t index) { this->trigger(StringRef(this->parent_->option_at(index)), index); });
   }
 
  protected:

esphome/components/select/select.h

@@ -80,23 +80,21 @@ class Select : public EntityBase {
 
   void add_on_state_callback(std::function<void(size_t)> &&callback);
 
- protected:
-  friend class SelectCall;
-
-  size_t active_index_{0};
-
   /** Set the value of the select by index, this is an optional virtual method.
-   *
-   * IMPORTANT: At least ONE of the two control() methods must be overridden by derived classes.
-   * Overriding this index-based version is PREFERRED as it avoids string conversions.
    *
    * This method is called by the SelectCall when the index is already known.
-   * Default implementation converts to string and calls control(const std::string&).
+   * Default implementation converts to string and calls control().
+   * Override this to work directly with indices and avoid string conversions.
    *
    * @param index The index as validated by the SelectCall.
    */
   virtual void control(size_t index) { this->control(this->option_at(index)); }
 
+ protected:
+  friend class SelectCall;
+
+  size_t active_index_{0};
+
   /** Set the value of the select, this is a virtual method that each select integration can implement.
    *
    * IMPORTANT: At least ONE of the two control() methods must be overridden by derived classes.

esphome/components/sim800l/sim800l.cpp

@@ -1,4 +1,5 @@
 #include "sim800l.h"
+#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 #include <cstring>
 
@@ -50,8 +51,8 @@ void Sim800LComponent::update() {
   } else if (state_ == STATE_RECEIVED_SMS) {
     // Serial Buffer should have flushed.
     // Send cmd to delete received sms
-    char delete_cmd[20];
-    sprintf(delete_cmd, "AT+CMGD=%d", this->parse_index_);
+    char delete_cmd[20];  // "AT+CMGD=" (8) + int (max 11) + null = 20
+    buf_append_printf(delete_cmd, sizeof(delete_cmd), 0, "AT+CMGD=%d", this->parse_index_);
     this->send_cmd_(delete_cmd);
     this->state_ = STATE_CHECK_SMS;
     this->expect_ack_ = true;

esphome/components/sml/sml_parser.cpp

@@ -104,7 +104,10 @@ std::vector<ObisInfo> SmlFile::get_obis_info() {
 std::string bytes_repr(const BytesView &buffer) {
   std::string repr;
   for (auto const value : buffer) {
-    repr += str_sprintf("%02x", value & 0xff);
+    // max 3: 2 hex digits + null
+    char hex_buf[3];
+    snprintf(hex_buf, sizeof(hex_buf), "%02x", value & 0xff);
+    repr += hex_buf;
   }
   return repr;
 }
@@ -146,7 +149,11 @@ ObisInfo::ObisInfo(const BytesView &server_id, const SmlNode &val_list_entry) :
 }
 
 std::string ObisInfo::code_repr() const {
-  return str_sprintf("%d-%d:%d.%d.%d", this->code[0], this->code[1], this->code[2], this->code[3], this->code[4]);
+  // max 20: "255-255:255.255.255" (19 chars) + null
+  char buf[20];
+  snprintf(buf, sizeof(buf), "%d-%d:%d.%d.%d", this->code[0], this->code[1], this->code[2], this->code[3],
+           this->code[4]);
+  return buf;
 }
 
 }  // namespace sml

esphome/components/sn74hc165/sn74hc165.cpp

@@ -65,7 +65,7 @@ float SN74HC165Component::get_setup_priority() const { return setup_priority::IO
 bool SN74HC165GPIOPin::digital_read() { return this->parent_->digital_read_(this->pin_) != this->inverted_; }
 
 size_t SN74HC165GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return snprintf(buffer, len, "%u via SN74HC165", this->pin_);
+  return buf_append_printf(buffer, len, 0, "%u via SN74HC165", this->pin_);
 }
 
 }  // namespace sn74hc165

esphome/components/sn74hc595/sn74hc595.cpp

@@ -94,7 +94,7 @@ void SN74HC595GPIOPin::digital_write(bool value) {
   this->parent_->digital_write_(this->pin_, value != this->inverted_);
 }
 size_t SN74HC595GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return snprintf(buffer, len, "%u via SN74HC595", this->pin_);
+  return buf_append_printf(buffer, len, 0, "%u via SN74HC595", this->pin_);
 }
 
 }  // namespace sn74hc595

esphome/components/socket/socket.cpp

@@ -107,9 +107,9 @@ std::unique_ptr<Socket> socket_ip_loop_monitored(int type, int protocol) {
 #endif /* USE_NETWORK_IPV6 */
 }
 
-socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const std::string &ip_address, uint16_t port) {
+socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const char *ip_address, uint16_t port) {
 #if USE_NETWORK_IPV6
-  if (ip_address.find(':') != std::string::npos) {
+  if (strchr(ip_address, ':') != nullptr) {
     if (addrlen < sizeof(sockaddr_in6)) {
       errno = EINVAL;
       return 0;
@@ -121,14 +121,14 @@ socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const std::stri
 
 #ifdef USE_SOCKET_IMPL_BSD_SOCKETS
     // Use standard inet_pton for BSD sockets
-    if (inet_pton(AF_INET6, ip_address.c_str(), &server->sin6_addr) != 1) {
+    if (inet_pton(AF_INET6, ip_address, &server->sin6_addr) != 1) {
       errno = EINVAL;
       return 0;
     }
 #else
     // Use LWIP-specific functions
     ip6_addr_t ip6;
-    inet6_aton(ip_address.c_str(), &ip6);
+    inet6_aton(ip_address, &ip6);
     memcpy(server->sin6_addr.un.u32_addr, ip6.addr, sizeof(ip6.addr));
 #endif
     return sizeof(sockaddr_in6);
@@ -141,7 +141,7 @@ socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const std::stri
   auto *server = reinterpret_cast<sockaddr_in *>(addr);
   memset(server, 0, sizeof(sockaddr_in));
   server->sin_family = AF_INET;
-  server->sin_addr.s_addr = inet_addr(ip_address.c_str());
+  server->sin_addr.s_addr = inet_addr(ip_address);
   server->sin_port = htons(port);
   return sizeof(sockaddr_in);
 }

esphome/components/socket/socket.h

@@ -87,7 +87,17 @@ std::unique_ptr<Socket> socket_loop_monitored(int domain, int type, int protocol
 std::unique_ptr<Socket> socket_ip_loop_monitored(int type, int protocol);
 
 /// Set a sockaddr to the specified address and port for the IP version used by socket_ip().
-socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const std::string &ip_address, uint16_t port);
+/// @param addr Destination sockaddr structure
+/// @param addrlen Size of the addr buffer
+/// @param ip_address Null-terminated IP address string (IPv4 or IPv6)
+/// @param port Port number in host byte order
+/// @return Size of the sockaddr structure used, or 0 on error
+socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const char *ip_address, uint16_t port);
+
+/// Convenience overload for std::string (backward compatible).
+inline socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const std::string &ip_address, uint16_t port) {
+  return set_sockaddr(addr, addrlen, ip_address.c_str(), port);
+}
 
 /// Set a sockaddr to the any address and specified port for the IP version used by socket_ip().
 socklen_t set_sockaddr_any(struct sockaddr *addr, socklen_t addrlen, uint16_t port);

esphome/components/speed/fan/__init__.py

@@ -25,7 +25,7 @@ CONFIG_SCHEMA = (
             cv.Optional(CONF_SPEED): cv.invalid(
                 "Configuring individual speeds is deprecated."
             ),
-            cv.Optional(CONF_SPEED_COUNT, default=100): cv.int_range(min=1),
+            cv.Optional(CONF_SPEED_COUNT, default=100): cv.int_range(min=1, max=255),
             cv.Optional(CONF_PRESET_MODES): validate_preset_modes,
         }
     )

esphome/components/speed/fan/speed_fan.h

@@ -10,7 +10,7 @@ namespace speed {
 
 class SpeedFan : public Component, public fan::Fan {
  public:
-  SpeedFan(int speed_count) : speed_count_(speed_count) {}
+  SpeedFan(uint8_t speed_count) : speed_count_(speed_count) {}
   void setup() override;
   void dump_config() override;
   void set_output(output::FloatOutput *output) { this->output_ = output; }
@@ -26,7 +26,7 @@ class SpeedFan : public Component, public fan::Fan {
   output::FloatOutput *output_;
   output::BinaryOutput *oscillating_{nullptr};
   output::BinaryOutput *direction_{nullptr};
-  int speed_count_{};
+  uint8_t speed_count_{};
   fan::FanTraits traits_;
   std::vector<const char *> preset_modes_{};
 };