Merge branch 'dev' into mqtt_stack_part_2

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

.clang-tidy.hash

@@ -1 +1 @@
-d272a88e8ca28ae9340a9a03295a566432a52cb696501908f57764475bf7ca65
+15dc295268b2dcf75942f42759b3ddec64eba89f75525698eb39c95a7f4b14ce

.github/workflows/sync-device-classes.yml

@@ -41,7 +41,7 @@ jobs:
           python script/run-in-env.py pre-commit run --all-files
 
       - name: Commit changes
-        uses: peter-evans/create-pull-request@98357b18bf14b5342f975ff684046ec3b2a07725 # v8.0.0
+        uses: peter-evans/create-pull-request@c0f553fe549906ede9cf27b5156039d195d2ece0 # v8.1.0
         with:
           commit-message: "Synchronise Device Classes from Home Assistant"
           committer: esphomebot <esphome@openhomefoundation.org>

esphome/__main__.py

@@ -1,5 +1,6 @@
 # PYTHON_ARGCOMPLETE_OK
 import argparse
+from collections.abc import Callable
 from datetime import datetime
 import functools
 import getpass
@@ -42,6 +43,7 @@ from esphome.const import (
     CONF_SUBSTITUTIONS,
     CONF_TOPIC,
     ENV_NOGITIGNORE,
+    KEY_NATIVE_IDF,
     PLATFORM_ESP32,
     PLATFORM_ESP8266,
     PLATFORM_RP2040,
@@ -115,6 +117,7 @@ class ArgsProtocol(Protocol):
     configuration: str
     name: str
     upload_speed: str | None
+    native_idf: bool
 
 
 def choose_prompt(options, purpose: str = None):
@@ -499,12 +502,15 @@ def wrap_to_code(name, comp):
     return wrapped
 
 
-def write_cpp(config: ConfigType) -> int:
+def write_cpp(config: ConfigType, native_idf: bool = False) -> int:
     if not get_bool_env(ENV_NOGITIGNORE):
         writer.write_gitignore()
 
+    # Store native_idf flag so esp32 component can check it
+    CORE.data[KEY_NATIVE_IDF] = native_idf
+
     generate_cpp_contents(config)
-    return write_cpp_file()
+    return write_cpp_file(native_idf=native_idf)
 
 
 def generate_cpp_contents(config: ConfigType) -> None:
@@ -518,32 +524,54 @@ def generate_cpp_contents(config: ConfigType) -> None:
     CORE.flush_tasks()
 
 
-def write_cpp_file() -> int:
+def write_cpp_file(native_idf: bool = False) -> int:
     code_s = indent(CORE.cpp_main_section)
     writer.write_cpp(code_s)
 
-    from esphome.build_gen import platformio
+    if native_idf and CORE.is_esp32 and CORE.target_framework == "esp-idf":
+        from esphome.build_gen import espidf
 
-    platformio.write_project()
+        espidf.write_project()
+    else:
+        from esphome.build_gen import platformio
+
+        platformio.write_project()
 
     return 0
 
 
 def compile_program(args: ArgsProtocol, config: ConfigType) -> int:
-    from esphome import platformio_api
+    native_idf = getattr(args, "native_idf", False)
 
     # NOTE: "Build path:" format is parsed by script/ci_memory_impact_extract.py
     # If you change this format, update the regex in that script as well
     _LOGGER.info("Compiling app... Build path: %s", CORE.build_path)
-    rc = platformio_api.run_compile(config, CORE.verbose)
-    if rc != 0:
-        return rc
+
+    if native_idf and CORE.is_esp32 and CORE.target_framework == "esp-idf":
+        from esphome import espidf_api
+
+        rc = espidf_api.run_compile(config, CORE.verbose)
+        if rc != 0:
+            return rc
+
+        # Create factory.bin and ota.bin
+        espidf_api.create_factory_bin()
+        espidf_api.create_ota_bin()
+    else:
+        from esphome import platformio_api
+
+        rc = platformio_api.run_compile(config, CORE.verbose)
+        if rc != 0:
+            return rc
+
+        idedata = platformio_api.get_idedata(config)
+        if idedata is None:
+            return 1
 
     # Check if firmware was rebuilt and emit build_info + create manifest
     _check_and_emit_build_info()
 
-    idedata = platformio_api.get_idedata(config)
-    return 0 if idedata is not None else 1
+    return 0
 
 
 def _check_and_emit_build_info() -> None:
@@ -800,7 +828,8 @@ def command_vscode(args: ArgsProtocol) -> int | None:
 
 
 def command_compile(args: ArgsProtocol, config: ConfigType) -> int | None:
-    exit_code = write_cpp(config)
+    native_idf = getattr(args, "native_idf", False)
+    exit_code = write_cpp(config, native_idf=native_idf)
     if exit_code != 0:
         return exit_code
     if args.only_generate:
@@ -855,7 +884,8 @@ def command_logs(args: ArgsProtocol, config: ConfigType) -> int | None:
 
 
 def command_run(args: ArgsProtocol, config: ConfigType) -> int | None:
-    exit_code = write_cpp(config)
+    native_idf = getattr(args, "native_idf", False)
+    exit_code = write_cpp(config, native_idf=native_idf)
     if exit_code != 0:
         return exit_code
     exit_code = compile_program(args, config)
@@ -936,11 +966,21 @@ def command_dashboard(args: ArgsProtocol) -> int | None:
     return dashboard.start_dashboard(args)
 
 
-def command_update_all(args: ArgsProtocol) -> int | None:
+def run_multiple_configs(
+    files: list, command_builder: Callable[[str], list[str]]
+) -> int:
+    """Run a command for each configuration file in a subprocess.
+
+    Args:
+        files: List of configuration files to process.
+        command_builder: Callable that takes a file path and returns a command list.
+
+    Returns:
+        Number of failed files.
+    """
     import click
 
     success = {}
-    files = list_yaml_files(args.configuration)
     twidth = 60
 
     def print_bar(middle_text):
@@ -950,17 +990,19 @@ def command_update_all(args: ArgsProtocol) -> int | None:
         safe_print(f"{half_line}{middle_text}{half_line}")
 
     for f in files:
-        safe_print(f"Updating {color(AnsiFore.CYAN, str(f))}")
+        f_path = Path(f) if not isinstance(f, Path) else f
+
+        if any(f_path.name == x for x in SECRETS_FILES):
+            _LOGGER.warning("Skipping secrets file %s", f_path)
+            continue
+
+        safe_print(f"Processing {color(AnsiFore.CYAN, str(f))}")
         safe_print("-" * twidth)
         safe_print()
-        if CORE.dashboard:
-            rc = run_external_process(
-                "esphome", "--dashboard", "run", f, "--no-logs", "--device", "OTA"
-            )
-        else:
-            rc = run_external_process(
-                "esphome", "run", f, "--no-logs", "--device", "OTA"
-            )
+
+        cmd = command_builder(f)
+        rc = run_external_process(*cmd)
+
         if rc == 0:
             print_bar(f"[{color(AnsiFore.BOLD_GREEN, 'SUCCESS')}] {str(f)}")
             success[f] = True
@@ -975,6 +1017,8 @@ def command_update_all(args: ArgsProtocol) -> int | None:
     print_bar(f"[{color(AnsiFore.BOLD_WHITE, 'SUMMARY')}]")
     failed = 0
     for f in files:
+        if f not in success:
+            continue  # Skipped file
         if success[f]:
             safe_print(f"  - {str(f)}: {color(AnsiFore.GREEN, 'SUCCESS')}")
         else:
@@ -983,6 +1027,17 @@ def command_update_all(args: ArgsProtocol) -> int | None:
     return failed
 
 
+def command_update_all(args: ArgsProtocol) -> int | None:
+    files = list_yaml_files(args.configuration)
+
+    def build_command(f):
+        if CORE.dashboard:
+            return ["esphome", "--dashboard", "run", f, "--no-logs", "--device", "OTA"]
+        return ["esphome", "run", f, "--no-logs", "--device", "OTA"]
+
+    return run_multiple_configs(files, build_command)
+
+
 def command_idedata(args: ArgsProtocol, config: ConfigType) -> int:
     import json
 
@@ -1284,6 +1339,11 @@ def parse_args(argv):
         help="Only generate source code, do not compile.",
         action="store_true",
     )
+    parser_compile.add_argument(
+        "--native-idf",
+        help="Build with native ESP-IDF instead of PlatformIO (ESP32 esp-idf framework only).",
+        action="store_true",
+    )
 
     parser_upload = subparsers.add_parser(
         "upload",
@@ -1365,6 +1425,11 @@ def parse_args(argv):
         help="Reset the device before starting serial logs.",
         default=os.getenv("ESPHOME_SERIAL_LOGGING_RESET"),
     )
+    parser_run.add_argument(
+        "--native-idf",
+        help="Build with native ESP-IDF instead of PlatformIO (ESP32 esp-idf framework only).",
+        action="store_true",
+    )
 
     parser_clean = subparsers.add_parser(
         "clean-mqtt",
@@ -1533,38 +1598,48 @@ def run_esphome(argv):
 
     _LOGGER.info("ESPHome %s", const.__version__)
 
-    for conf_path in args.configuration:
-        conf_path = Path(conf_path)
-        if any(conf_path.name == x for x in SECRETS_FILES):
-            _LOGGER.warning("Skipping secrets file %s", conf_path)
-            continue
+    # Multiple configurations: use subprocesses to avoid state leakage
+    # between compilations (e.g., LVGL touchscreen state in module globals)
+    if len(args.configuration) > 1:
+        # Build command by reusing argv, replacing all configs with single file
+        # argv[0] is the program path, skip it since we prefix with "esphome"
+        def build_command(f):
+            return (
+                ["esphome"]
+                + [arg for arg in argv[1:] if arg not in args.configuration]
+                + [str(f)]
+            )
 
-        CORE.config_path = conf_path
-        CORE.dashboard = args.dashboard
+        return run_multiple_configs(args.configuration, build_command)
 
-        # For logs command, skip updating external components
-        skip_external = args.command == "logs"
-        config = read_config(
-            dict(args.substitution) if args.substitution else {},
-            skip_external_update=skip_external,
-        )
-        if config is None:
-            return 2
-        CORE.config = config
+    # Single configuration
+    conf_path = Path(args.configuration[0])
+    if any(conf_path.name == x for x in SECRETS_FILES):
+        _LOGGER.warning("Skipping secrets file %s", conf_path)
+        return 0
 
-        if args.command not in POST_CONFIG_ACTIONS:
-            safe_print(f"Unknown command {args.command}")
+    CORE.config_path = conf_path
+    CORE.dashboard = args.dashboard
 
-        try:
-            rc = POST_CONFIG_ACTIONS[args.command](args, config)
-        except EsphomeError as e:
-            _LOGGER.error(e, exc_info=args.verbose)
-            return 1
-        if rc != 0:
-            return rc
+    # For logs command, skip updating external components
+    skip_external = args.command == "logs"
+    config = read_config(
+        dict(args.substitution) if args.substitution else {},
+        skip_external_update=skip_external,
+    )
+    if config is None:
+        return 2
+    CORE.config = config
 
-        CORE.reset()
-    return 0
+    if args.command not in POST_CONFIG_ACTIONS:
+        safe_print(f"Unknown command {args.command}")
+        return 1
+
+    try:
+        return POST_CONFIG_ACTIONS[args.command](args, config)
+    except EsphomeError as e:
+        _LOGGER.error(e, exc_info=args.verbose)
+        return 1
 
 
 def main():

esphome/build_gen/espidf.py

@@ -0,0 +1,139 @@
+"""ESP-IDF direct build generator for ESPHome."""
+
+import json
+from pathlib import Path
+
+from esphome.components.esp32 import get_esp32_variant
+from esphome.core import CORE
+from esphome.helpers import mkdir_p, write_file_if_changed
+
+
+def get_available_components() -> list[str] | None:
+    """Get list of available ESP-IDF components from project_description.json.
+
+    Returns only internal ESP-IDF components, excluding external/managed
+    components (from idf_component.yml).
+    """
+    project_desc = Path(CORE.build_path) / "build" / "project_description.json"
+    if not project_desc.exists():
+        return None
+
+    try:
+        with open(project_desc, encoding="utf-8") as f:
+            data = json.load(f)
+
+        component_info = data.get("build_component_info", {})
+
+        result = []
+        for name, info in component_info.items():
+            # Exclude our own src component
+            if name == "src":
+                continue
+
+            # Exclude managed/external components
+            comp_dir = info.get("dir", "")
+            if "managed_components" in comp_dir:
+                continue
+
+            result.append(name)
+
+        return result
+    except (json.JSONDecodeError, OSError):
+        return None
+
+
+def has_discovered_components() -> bool:
+    """Check if we have discovered components from a previous configure."""
+    return get_available_components() is not None
+
+
+def get_project_cmakelists() -> str:
+    """Generate the top-level CMakeLists.txt for ESP-IDF project."""
+    # Get IDF target from ESP32 variant (e.g., ESP32S3 -> esp32s3)
+    variant = get_esp32_variant()
+    idf_target = variant.lower().replace("-", "")
+
+    return f"""\
+# Auto-generated by ESPHome
+cmake_minimum_required(VERSION 3.16)
+
+set(IDF_TARGET {idf_target})
+set(EXTRA_COMPONENT_DIRS ${{CMAKE_SOURCE_DIR}}/src)
+
+include($ENV{{IDF_PATH}}/tools/cmake/project.cmake)
+project({CORE.name})
+"""
+
+
+def get_component_cmakelists(minimal: bool = False) -> str:
+    """Generate the main component CMakeLists.txt."""
+    idf_requires = [] if minimal else (get_available_components() or [])
+    requires_str = " ".join(idf_requires)
+
+    # Extract compile definitions from build flags (-DXXX -> XXX)
+    compile_defs = [flag[2:] for flag in CORE.build_flags if flag.startswith("-D")]
+    compile_defs_str = "\n    ".join(compile_defs) if compile_defs else ""
+
+    # Extract compile options (-W flags, excluding linker flags)
+    compile_opts = [
+        flag
+        for flag in CORE.build_flags
+        if flag.startswith("-W") and not flag.startswith("-Wl,")
+    ]
+    compile_opts_str = "\n    ".join(compile_opts) if compile_opts else ""
+
+    # Extract linker options (-Wl, flags)
+    link_opts = [flag for flag in CORE.build_flags if flag.startswith("-Wl,")]
+    link_opts_str = "\n    ".join(link_opts) if link_opts else ""
+
+    return f"""\
+# Auto-generated by ESPHome
+file(GLOB_RECURSE app_sources
+    "${{CMAKE_CURRENT_SOURCE_DIR}}/*.cpp"
+    "${{CMAKE_CURRENT_SOURCE_DIR}}/*.c"
+    "${{CMAKE_CURRENT_SOURCE_DIR}}/esphome/*.cpp"
+    "${{CMAKE_CURRENT_SOURCE_DIR}}/esphome/*.c"
+)
+
+idf_component_register(
+    SRCS ${{app_sources}}
+    INCLUDE_DIRS "." "esphome"
+    REQUIRES {requires_str}
+)
+
+# Apply C++ standard
+target_compile_features(${{COMPONENT_LIB}} PUBLIC cxx_std_20)
+
+# ESPHome compile definitions
+target_compile_definitions(${{COMPONENT_LIB}} PUBLIC
+    {compile_defs_str}
+)
+
+# ESPHome compile options
+target_compile_options(${{COMPONENT_LIB}} PUBLIC
+    {compile_opts_str}
+)
+
+# ESPHome linker options
+target_link_options(${{COMPONENT_LIB}} PUBLIC
+    {link_opts_str}
+)
+"""
+
+
+def write_project(minimal: bool = False) -> None:
+    """Write ESP-IDF project files."""
+    mkdir_p(CORE.build_path)
+    mkdir_p(CORE.relative_src_path())
+
+    # Write top-level CMakeLists.txt
+    write_file_if_changed(
+        CORE.relative_build_path("CMakeLists.txt"),
+        get_project_cmakelists(),
+    )
+
+    # Write component CMakeLists.txt in src/
+    write_file_if_changed(
+        CORE.relative_src_path("CMakeLists.txt"),
+        get_component_cmakelists(minimal=minimal),
+    )

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/adc/sensor.py

@@ -160,21 +160,21 @@ async def to_code(config):
         zephyr_add_user("io-channels", f"<&adc {channel_id}>")
         zephyr_add_overlay(
             f"""
-&adc {{
-    #address-cells = <1>;
-    #size-cells = <0>;
+                &adc {{
+                    #address-cells = <1>;
+                    #size-cells = <0>;
 
-    channel@{channel_id} {{
-        reg = <{channel_id}>;
-        zephyr,gain = "{gain}";
-        zephyr,reference = "ADC_REF_INTERNAL";
-        zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
-        zephyr,input-positive = <NRF_SAADC_{pin_number}>;
-        zephyr,resolution = <14>;
-        zephyr,oversampling = <8>;
-    }};
-}};
-"""
+                    channel@{channel_id} {{
+                        reg = <{channel_id}>;
+                        zephyr,gain = "{gain}";
+                        zephyr,reference = "ADC_REF_INTERNAL";
+                        zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
+                        zephyr,input-positive = <NRF_SAADC_{pin_number}>;
+                        zephyr,resolution = <14>;
+                        zephyr,oversampling = <8>;
+                    }};
+                }};
+            """
         )
 
 

esphome/components/alarm_control_panel/alarm_control_panel.cpp

@@ -67,52 +67,29 @@ void AlarmControlPanel::add_on_ready_callback(std::function<void()> &&callback)
   this->ready_callback_.add(std::move(callback));
 }
 
-void AlarmControlPanel::arm_away(optional<std::string> code) {
+void AlarmControlPanel::arm_with_code_(AlarmControlPanelCall &(AlarmControlPanelCall::*arm_method)(),
+                                       const char *code) {
   auto call = this->make_call();
-  call.arm_away();
-  if (code.has_value())
-    call.set_code(code.value());
+  (call.*arm_method)();
+  if (code != nullptr)
+    call.set_code(code);
   call.perform();
 }
 
-void AlarmControlPanel::arm_home(optional<std::string> code) {
-  auto call = this->make_call();
-  call.arm_home();
-  if (code.has_value())
-    call.set_code(code.value());
-  call.perform();
+void AlarmControlPanel::arm_away(const char *code) { this->arm_with_code_(&AlarmControlPanelCall::arm_away, code); }
+
+void AlarmControlPanel::arm_home(const char *code) { this->arm_with_code_(&AlarmControlPanelCall::arm_home, code); }
+
+void AlarmControlPanel::arm_night(const char *code) { this->arm_with_code_(&AlarmControlPanelCall::arm_night, code); }
+
+void AlarmControlPanel::arm_vacation(const char *code) {
+  this->arm_with_code_(&AlarmControlPanelCall::arm_vacation, code);
 }
 
-void AlarmControlPanel::arm_night(optional<std::string> code) {
-  auto call = this->make_call();
-  call.arm_night();
-  if (code.has_value())
-    call.set_code(code.value());
-  call.perform();
+void AlarmControlPanel::arm_custom_bypass(const char *code) {
+  this->arm_with_code_(&AlarmControlPanelCall::arm_custom_bypass, code);
 }
 
-void AlarmControlPanel::arm_vacation(optional<std::string> code) {
-  auto call = this->make_call();
-  call.arm_vacation();
-  if (code.has_value())
-    call.set_code(code.value());
-  call.perform();
-}
-
-void AlarmControlPanel::arm_custom_bypass(optional<std::string> code) {
-  auto call = this->make_call();
-  call.arm_custom_bypass();
-  if (code.has_value())
-    call.set_code(code.value());
-  call.perform();
-}
-
-void AlarmControlPanel::disarm(optional<std::string> code) {
-  auto call = this->make_call();
-  call.disarm();
-  if (code.has_value())
-    call.set_code(code.value());
-  call.perform();
-}
+void AlarmControlPanel::disarm(const char *code) { this->arm_with_code_(&AlarmControlPanelCall::disarm, code); }
 
 }  // namespace esphome::alarm_control_panel

esphome/components/alarm_control_panel/alarm_control_panel.h

@@ -76,37 +76,53 @@ class AlarmControlPanel : public EntityBase {
    *
    * @param code The code
    */
-  void arm_away(optional<std::string> code = nullopt);
+  void arm_away(const char *code = nullptr);
+  void arm_away(const optional<std::string> &code) {
+    this->arm_away(code.has_value() ? code.value().c_str() : nullptr);
+  }
 
   /** arm the alarm in home mode
    *
    * @param code The code
    */
-  void arm_home(optional<std::string> code = nullopt);
+  void arm_home(const char *code = nullptr);
+  void arm_home(const optional<std::string> &code) {
+    this->arm_home(code.has_value() ? code.value().c_str() : nullptr);
+  }
 
   /** arm the alarm in night mode
    *
    * @param code The code
    */
-  void arm_night(optional<std::string> code = nullopt);
+  void arm_night(const char *code = nullptr);
+  void arm_night(const optional<std::string> &code) {
+    this->arm_night(code.has_value() ? code.value().c_str() : nullptr);
+  }
 
   /** arm the alarm in vacation mode
    *
    * @param code The code
    */
-  void arm_vacation(optional<std::string> code = nullopt);
+  void arm_vacation(const char *code = nullptr);
+  void arm_vacation(const optional<std::string> &code) {
+    this->arm_vacation(code.has_value() ? code.value().c_str() : nullptr);
+  }
 
   /** arm the alarm in custom bypass mode
    *
    * @param code The code
    */
-  void arm_custom_bypass(optional<std::string> code = nullopt);
+  void arm_custom_bypass(const char *code = nullptr);
+  void arm_custom_bypass(const optional<std::string> &code) {
+    this->arm_custom_bypass(code.has_value() ? code.value().c_str() : nullptr);
+  }
 
   /** disarm the alarm
    *
    * @param code The code
    */
-  void disarm(optional<std::string> code = nullopt);
+  void disarm(const char *code = nullptr);
+  void disarm(const optional<std::string> &code) { this->disarm(code.has_value() ? code.value().c_str() : nullptr); }
 
   /** Get the state
    *
@@ -118,6 +134,8 @@ class AlarmControlPanel : public EntityBase {
 
  protected:
   friend AlarmControlPanelCall;
+  // Helper to reduce code duplication for arm/disarm methods
+  void arm_with_code_(AlarmControlPanelCall &(AlarmControlPanelCall::*arm_method)(), const char *code);
   // in order to store last panel state in flash
   ESPPreferenceObject pref_;
   // current state

esphome/components/alarm_control_panel/alarm_control_panel_call.cpp

@@ -10,8 +10,10 @@ static const char *const TAG = "alarm_control_panel";
 
 AlarmControlPanelCall::AlarmControlPanelCall(AlarmControlPanel *parent) : parent_(parent) {}
 
-AlarmControlPanelCall &AlarmControlPanelCall::set_code(const std::string &code) {
-  this->code_ = code;
+AlarmControlPanelCall &AlarmControlPanelCall::set_code(const char *code) {
+  if (code != nullptr) {
+    this->code_ = std::string(code);
+  }
   return *this;
 }
 

esphome/components/alarm_control_panel/alarm_control_panel_call.h

@@ -14,7 +14,8 @@ class AlarmControlPanelCall {
  public:
   AlarmControlPanelCall(AlarmControlPanel *parent);
 
-  AlarmControlPanelCall &set_code(const std::string &code);
+  AlarmControlPanelCall &set_code(const char *code);
+  AlarmControlPanelCall &set_code(const std::string &code) { return this->set_code(code.c_str()); }
   AlarmControlPanelCall &arm_away();
   AlarmControlPanelCall &arm_home();
   AlarmControlPanelCall &arm_night();

esphome/components/alarm_control_panel/automation.h

@@ -66,15 +66,7 @@ template<typename... Ts> class ArmAwayAction : public Action<Ts...> {
 
   TEMPLATABLE_VALUE(std::string, code)
 
-  void play(const Ts &...x) override {
-    auto call = this->alarm_control_panel_->make_call();
-    auto code = this->code_.optional_value(x...);
-    if (code.has_value()) {
-      call.set_code(code.value());
-    }
-    call.arm_away();
-    call.perform();
-  }
+  void play(const Ts &...x) override { this->alarm_control_panel_->arm_away(this->code_.optional_value(x...)); }
 
  protected:
   AlarmControlPanel *alarm_control_panel_;
@@ -86,15 +78,7 @@ template<typename... Ts> class ArmHomeAction : public Action<Ts...> {
 
   TEMPLATABLE_VALUE(std::string, code)
 
-  void play(const Ts &...x) override {
-    auto call = this->alarm_control_panel_->make_call();
-    auto code = this->code_.optional_value(x...);
-    if (code.has_value()) {
-      call.set_code(code.value());
-    }
-    call.arm_home();
-    call.perform();
-  }
+  void play(const Ts &...x) override { this->alarm_control_panel_->arm_home(this->code_.optional_value(x...)); }
 
  protected:
   AlarmControlPanel *alarm_control_panel_;
@@ -106,15 +90,7 @@ template<typename... Ts> class ArmNightAction : public Action<Ts...> {
 
   TEMPLATABLE_VALUE(std::string, code)
 
-  void play(const Ts &...x) override {
-    auto call = this->alarm_control_panel_->make_call();
-    auto code = this->code_.optional_value(x...);
-    if (code.has_value()) {
-      call.set_code(code.value());
-    }
-    call.arm_night();
-    call.perform();
-  }
+  void play(const Ts &...x) override { this->alarm_control_panel_->arm_night(this->code_.optional_value(x...)); }
 
  protected:
   AlarmControlPanel *alarm_control_panel_;

esphome/components/am43/am43_base.cpp

@@ -1,21 +1,12 @@
 #include "am43_base.h"
+#include "esphome/core/helpers.h"
 #include <cstring>
-#include <cstdio>
 
 namespace esphome {
 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;
-}
-
 Am43Packet *Am43Encoder::get_battery_level_request() {
   uint8_t data = 0x1;
   return this->encode_(0xA2, &data, 1);
@@ -73,7 +64,9 @@ Am43Packet *Am43Encoder::encode_(uint8_t command, uint8_t *data, uint8_t length)
   memcpy(&this->packet_.data[7], data, length);
   this->packet_.length = length + 7;
   this->checksum_();
-  ESP_LOGV("am43", "ENC(%d): 0x%s", packet_.length, pkt_to_hex(packet_.data, packet_.length).c_str());
+  char hex_buf[format_hex_size(sizeof(this->packet_.data))];
+  ESP_LOGV("am43", "ENC(%d): 0x%s", this->packet_.length,
+           format_hex_to(hex_buf, this->packet_.data, this->packet_.length));
   return &this->packet_;
 }
 
@@ -88,7 +81,8 @@ void Am43Decoder::decode(const uint8_t *data, uint16_t length) {
   this->has_set_state_response_ = false;
   this->has_position_ = false;
   this->has_pin_response_ = false;
-  ESP_LOGV("am43", "DEC(%d): 0x%s", length, pkt_to_hex(data, length).c_str());
+  char hex_buf[format_hex_size(24)];  // Max expected packet size
+  ESP_LOGV("am43", "DEC(%d): 0x%s", length, format_hex_to(hex_buf, data, length));
 
   if (length < 2 || data[0] != 0x9a)
     return;

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);
+  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_READ_DEVICE_STATUS);
   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);
+  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_READ_TARGET_TEMP);
   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);
+  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_READ_CURRENT_TEMP);
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_read_unit_request() {
   this->current_query_ = READ_UNIT;
-  sprintf((char *) this->packet_.data, "%s", CMD_READ_UNIT);
+  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_READ_UNIT);
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_read_data_request() {
   this->current_query_ = READ_DATA;
-  sprintf((char *) this->packet_.data, "%s", CMD_READ_DATA);
+  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_READ_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);
+  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_START);
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_stop_request() {
   this->current_query_ = STOP;
-  sprintf((char *) this->packet_.data, CMD_STOP);
+  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_STOP);
   return this->clean_packet_();
 }
 

esphome/components/api/api_connection.cpp

@@ -1715,7 +1715,7 @@ void APIConnection::on_home_assistant_state_response(const HomeAssistantStateRes
     // HA state max length is 255 characters, but attributes can be much longer
     // Use stack buffer for common case (states), heap fallback for large attributes
     size_t state_len = msg.state.size();
-    SmallBufferWithHeapFallback<256> state_buf_alloc(state_len + 1);
+    SmallBufferWithHeapFallback<MAX_STATE_LEN + 1> state_buf_alloc(state_len + 1);
     char *state_buf = reinterpret_cast<char *>(state_buf_alloc.get());
     if (state_len > 0) {
       memcpy(state_buf, msg.state.c_str(), state_len);

esphome/components/api/api_frame_helper_noise.cpp

@@ -3,6 +3,7 @@
 #ifdef USE_API_NOISE
 #include "api_connection.h"  // For ClientInfo struct
 #include "esphome/core/application.h"
+#include "esphome/core/entity_base.h"
 #include "esphome/core/hal.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
@@ -256,28 +257,30 @@ APIError APINoiseFrameHelper::state_action_() {
   }
   if (state_ == State::SERVER_HELLO) {
     // send server hello
-    constexpr size_t mac_len = 13;  // 12 hex chars + null terminator
     const std::string &name = App.get_name();
-    char mac[mac_len];
+    char mac[MAC_ADDRESS_BUFFER_SIZE];
     get_mac_address_into_buffer(mac);
 
     // Calculate positions and sizes
     size_t name_len = name.size() + 1;  // including null terminator
     size_t name_offset = 1;
     size_t mac_offset = name_offset + name_len;
-    size_t total_size = 1 + name_len + mac_len;
+    size_t total_size = 1 + name_len + MAC_ADDRESS_BUFFER_SIZE;
 
-    auto msg = std::make_unique<uint8_t[]>(total_size);
+    // 1 (proto) + name (max ESPHOME_DEVICE_NAME_MAX_LEN) + 1 (name null)
+    // + mac (MAC_ADDRESS_BUFFER_SIZE - 1) + 1 (mac null)
+    constexpr size_t max_msg_size = 1 + ESPHOME_DEVICE_NAME_MAX_LEN + 1 + MAC_ADDRESS_BUFFER_SIZE;
+    uint8_t msg[max_msg_size];
 
     // chosen proto
     msg[0] = 0x01;
 
     // node name, terminated by null byte
-    std::memcpy(msg.get() + name_offset, name.c_str(), name_len);
+    std::memcpy(msg + name_offset, name.c_str(), name_len);
     // node mac, terminated by null byte
-    std::memcpy(msg.get() + mac_offset, mac, mac_len);
+    std::memcpy(msg + mac_offset, mac, MAC_ADDRESS_BUFFER_SIZE);
 
-    aerr = write_frame_(msg.get(), total_size);
+    aerr = write_frame_(msg, total_size);
     if (aerr != APIError::OK)
       return aerr;
 
@@ -353,35 +356,32 @@ APIError APINoiseFrameHelper::state_action_() {
   return APIError::OK;
 }
 void APINoiseFrameHelper::send_explicit_handshake_reject_(const LogString *reason) {
+  // Max reject message: "Bad handshake packet len" (24) + 1 (failure byte) = 25 bytes
+  uint8_t data[32];
+  data[0] = 0x01;  // failure
+
 #ifdef USE_STORE_LOG_STR_IN_FLASH
   // On ESP8266 with flash strings, we need to use PROGMEM-aware functions
   size_t reason_len = strlen_P(reinterpret_cast<PGM_P>(reason));
-  size_t data_size = reason_len + 1;
-  auto data = std::make_unique<uint8_t[]>(data_size);
-  data[0] = 0x01;  // failure
-
-  // Copy error message from PROGMEM
   if (reason_len > 0) {
-    memcpy_P(data.get() + 1, reinterpret_cast<PGM_P>(reason), reason_len);
+    memcpy_P(data + 1, reinterpret_cast<PGM_P>(reason), reason_len);
   }
 #else
   // Normal memory access
   const char *reason_str = LOG_STR_ARG(reason);
   size_t reason_len = strlen(reason_str);
-  size_t data_size = reason_len + 1;
-  auto data = std::make_unique<uint8_t[]>(data_size);
-  data[0] = 0x01;  // failure
-
-  // Copy error message in bulk
   if (reason_len > 0) {
-    std::memcpy(data.get() + 1, reason_str, reason_len);
+    // NOLINTNEXTLINE(bugprone-not-null-terminated-result) - binary protocol, not a C string
+    std::memcpy(data + 1, reason_str, reason_len);
   }
 #endif
 
+  size_t data_size = reason_len + 1;
+
   // temporarily remove failed state
   auto orig_state = state_;
   state_ = State::EXPLICIT_REJECT;
-  write_frame_(data.get(), data_size);
+  write_frame_(data, data_size);
   state_ = orig_state;
 }
 APIError APINoiseFrameHelper::read_packet(ReadPacketBuffer *buffer) {

esphome/components/audio/__init__.py

@@ -1,4 +1,5 @@
 import esphome.codegen as cg
+from esphome.components.esp32 import add_idf_component
 import esphome.config_validation as cv
 from esphome.const import CONF_BITS_PER_SAMPLE, CONF_NUM_CHANNELS, CONF_SAMPLE_RATE
 import esphome.final_validate as fv
@@ -165,4 +166,7 @@ def final_validate_audio_schema(
 
 
 async def to_code(config):
-    cg.add_library("esphome/esp-audio-libs", "2.0.1")
+    add_idf_component(
+        name="esphome/esp-audio-libs",
+        ref="2.0.3",
+    )

esphome/components/audio/audio_decoder.cpp

@@ -300,7 +300,7 @@ FileDecoderState AudioDecoder::decode_mp3_() {
 
   // Advance read pointer to match the offset for the syncword
   this->input_transfer_buffer_->decrease_buffer_length(offset);
-  uint8_t *buffer_start = this->input_transfer_buffer_->get_buffer_start();
+  const uint8_t *buffer_start = this->input_transfer_buffer_->get_buffer_start();
 
   buffer_length = (int) this->input_transfer_buffer_->available();
   int err = esp_audio_libs::helix_decoder::MP3Decode(this->mp3_decoder_, &buffer_start, &buffer_length,

esphome/components/bluetooth_proxy/bluetooth_connection.cpp

@@ -135,8 +135,8 @@ void BluetoothConnection::loop() {
   // - For V3_WITH_CACHE: Services are never sent, disable after INIT state
   // - For V3_WITHOUT_CACHE: Disable only after service discovery is complete
   //   (send_service_ == DONE_SENDING_SERVICES, which is only set after services are sent)
-  if (this->state_ != espbt::ClientState::INIT && (this->connection_type_ == espbt::ConnectionType::V3_WITH_CACHE ||
-                                                   this->send_service_ == DONE_SENDING_SERVICES)) {
+  if (this->state() != espbt::ClientState::INIT && (this->connection_type_ == espbt::ConnectionType::V3_WITH_CACHE ||
+                                                    this->send_service_ == DONE_SENDING_SERVICES)) {
     this->disable_loop();
   }
 }

esphome/components/cc1101/cc1101.cpp

@@ -152,6 +152,13 @@ void CC1101Component::setup() {
   }
 }
 
+void CC1101Component::call_listeners_(const std::vector<uint8_t> &packet, float freq_offset, float rssi, uint8_t lqi) {
+  for (auto &listener : this->listeners_) {
+    listener->on_packet(packet, freq_offset, rssi, lqi);
+  }
+  this->packet_trigger_->trigger(packet, freq_offset, rssi, lqi);
+}
+
 void CC1101Component::loop() {
   if (this->state_.PKT_FORMAT != static_cast<uint8_t>(PacketFormat::PACKET_FORMAT_FIFO) || this->gdo0_pin_ == nullptr ||
       !this->gdo0_pin_->digital_read()) {
@@ -198,7 +205,7 @@ void CC1101Component::loop() {
   bool crc_ok = (this->state_.LQI & STATUS_CRC_OK_MASK) != 0;
   uint8_t lqi = this->state_.LQI & STATUS_LQI_MASK;
   if (this->state_.CRC_EN == 0 || crc_ok) {
-    this->packet_trigger_->trigger(this->packet_, freq_offset, rssi, lqi);
+    this->call_listeners_(this->packet_, freq_offset, rssi, lqi);
   }
 
   // Return to rx

esphome/components/cc1101/cc1101.h

@@ -11,6 +11,11 @@ namespace esphome::cc1101 {
 
 enum class CC1101Error { NONE = 0, TIMEOUT, PARAMS, CRC_ERROR, FIFO_OVERFLOW, PLL_LOCK };
 
+class CC1101Listener {
+ public:
+  virtual void on_packet(const std::vector<uint8_t> &packet, float freq_offset, float rssi, uint8_t lqi) = 0;
+};
+
 class CC1101Component : public Component,
                         public spi::SPIDevice<spi::BIT_ORDER_MSB_FIRST, spi::CLOCK_POLARITY_LOW,
                                               spi::CLOCK_PHASE_LEADING, spi::DATA_RATE_1MHZ> {
@@ -73,6 +78,7 @@ class CC1101Component : public Component,
 
   // Packet mode operations
   CC1101Error transmit_packet(const std::vector<uint8_t> &packet);
+  void register_listener(CC1101Listener *listener) { this->listeners_.push_back(listener); }
   Trigger<std::vector<uint8_t>, float, float, uint8_t> *get_packet_trigger() const { return this->packet_trigger_; }
 
  protected:
@@ -89,9 +95,11 @@ class CC1101Component : public Component,
   InternalGPIOPin *gdo0_pin_{nullptr};
 
   // Packet handling
+  void call_listeners_(const std::vector<uint8_t> &packet, float freq_offset, float rssi, uint8_t lqi);
   Trigger<std::vector<uint8_t>, float, float, uint8_t> *packet_trigger_{
       new Trigger<std::vector<uint8_t>, float, float, uint8_t>()};
   std::vector<uint8_t> packet_;
+  std::vector<CC1101Listener *> listeners_;
 
   // Low-level Helpers
   uint8_t strobe_(Command cmd);

esphome/components/cs5460a/cs5460a.h

@@ -76,7 +76,6 @@ class CS5460AComponent : public Component,
   void restart() { restart_(); }
 
   void setup() override;
-  void loop() override {}
   void dump_config() override;
 
  protected:

esphome/components/datetime/date_entity.cpp

@@ -106,9 +106,9 @@ DateCall &DateCall::set_date(uint16_t year, uint8_t month, uint8_t day) {
 
 DateCall &DateCall::set_date(ESPTime time) { return this->set_date(time.year, time.month, time.day_of_month); };
 
-DateCall &DateCall::set_date(const std::string &date) {
+DateCall &DateCall::set_date(const char *date, size_t len) {
   ESPTime val{};
-  if (!ESPTime::strptime(date, val)) {
+  if (!ESPTime::strptime(date, len, val)) {
     ESP_LOGE(TAG, "Could not convert the date string to an ESPTime object");
     return *this;
   }

esphome/components/datetime/date_entity.h

@@ -67,7 +67,9 @@ class DateCall {
   void perform();
   DateCall &set_date(uint16_t year, uint8_t month, uint8_t day);
   DateCall &set_date(ESPTime time);
-  DateCall &set_date(const std::string &date);
+  DateCall &set_date(const char *date, size_t len);
+  DateCall &set_date(const char *date) { return this->set_date(date, strlen(date)); }
+  DateCall &set_date(const std::string &date) { return this->set_date(date.c_str(), date.size()); }
 
   DateCall &set_year(uint16_t year) {
     this->year_ = year;

esphome/components/datetime/datetime_entity.cpp

@@ -163,9 +163,9 @@ DateTimeCall &DateTimeCall::set_datetime(ESPTime datetime) {
                             datetime.second);
 };
 
-DateTimeCall &DateTimeCall::set_datetime(const std::string &datetime) {
+DateTimeCall &DateTimeCall::set_datetime(const char *datetime, size_t len) {
   ESPTime val{};
-  if (!ESPTime::strptime(datetime, val)) {
+  if (!ESPTime::strptime(datetime, len, val)) {
     ESP_LOGE(TAG, "Could not convert the time string to an ESPTime object");
     return *this;
   }

esphome/components/datetime/datetime_entity.h

@@ -71,7 +71,11 @@ class DateTimeCall {
   void perform();
   DateTimeCall &set_datetime(uint16_t year, uint8_t month, uint8_t day, uint8_t hour, uint8_t minute, uint8_t second);
   DateTimeCall &set_datetime(ESPTime datetime);
-  DateTimeCall &set_datetime(const std::string &datetime);
+  DateTimeCall &set_datetime(const char *datetime, size_t len);
+  DateTimeCall &set_datetime(const char *datetime) { return this->set_datetime(datetime, strlen(datetime)); }
+  DateTimeCall &set_datetime(const std::string &datetime) {
+    return this->set_datetime(datetime.c_str(), datetime.size());
+  }
   DateTimeCall &set_datetime(time_t epoch_seconds);
 
   DateTimeCall &set_year(uint16_t year) {

esphome/components/datetime/time_entity.cpp

@@ -74,9 +74,9 @@ TimeCall &TimeCall::set_time(uint8_t hour, uint8_t minute, uint8_t second) {
 
 TimeCall &TimeCall::set_time(ESPTime time) { return this->set_time(time.hour, time.minute, time.second); };
 
-TimeCall &TimeCall::set_time(const std::string &time) {
+TimeCall &TimeCall::set_time(const char *time, size_t len) {
   ESPTime val{};
-  if (!ESPTime::strptime(time, val)) {
+  if (!ESPTime::strptime(time, len, val)) {
     ESP_LOGE(TAG, "Could not convert the time string to an ESPTime object");
     return *this;
   }

esphome/components/datetime/time_entity.h

@@ -69,7 +69,9 @@ class TimeCall {
   void perform();
   TimeCall &set_time(uint8_t hour, uint8_t minute, uint8_t second);
   TimeCall &set_time(ESPTime time);
-  TimeCall &set_time(const std::string &time);
+  TimeCall &set_time(const char *time, size_t len);
+  TimeCall &set_time(const char *time) { return this->set_time(time, strlen(time)); }
+  TimeCall &set_time(const std::string &time) { return this->set_time(time.c_str(), time.size()); }
 
   TimeCall &set_hour(uint8_t hour) {
     this->hour_ = hour;

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

@@ -3,21 +3,80 @@
 #include "esphome/core/log.h"
 #include <Esp.h>
 
+extern "C" {
+#include <user_interface.h>
+
+// Global reset info struct populated by SDK at boot
+extern struct rst_info resetInfo;
+
+// Core version - either a string pointer or a version number to format as hex
+extern uint32_t core_version;
+extern const char *core_release;
+}
+
 namespace esphome {
 namespace debug {
 
 static const char *const TAG = "debug";
 
+// Get reset reason string from reason code (no heap allocation)
+// Returns LogString* pointing to flash (PROGMEM) on ESP8266
+static const LogString *get_reset_reason_str(uint32_t reason) {
+  switch (reason) {
+    case REASON_DEFAULT_RST:
+      return LOG_STR("Power On");
+    case REASON_WDT_RST:
+      return LOG_STR("Hardware Watchdog");
+    case REASON_EXCEPTION_RST:
+      return LOG_STR("Exception");
+    case REASON_SOFT_WDT_RST:
+      return LOG_STR("Software Watchdog");
+    case REASON_SOFT_RESTART:
+      return LOG_STR("Software/System restart");
+    case REASON_DEEP_SLEEP_AWAKE:
+      return LOG_STR("Deep-Sleep Wake");
+    case REASON_EXT_SYS_RST:
+      return LOG_STR("External System");
+    default:
+      return LOG_STR("Unknown");
+  }
+}
+
+// Size for core version hex buffer
+static constexpr size_t CORE_VERSION_BUFFER_SIZE = 12;
+
+// Get core version string (no heap allocation)
+// Returns either core_release directly or formats core_version as hex into provided buffer
+static const char *get_core_version_str(std::span<char, CORE_VERSION_BUFFER_SIZE> buffer) {
+  if (core_release != nullptr) {
+    return core_release;
+  }
+  snprintf_P(buffer.data(), CORE_VERSION_BUFFER_SIZE, PSTR("%08x"), core_version);
+  return buffer.data();
+}
+
+// Size for reset info buffer
+static constexpr size_t RESET_INFO_BUFFER_SIZE = 200;
+
+// Get detailed reset info string (no heap allocation)
+// For watchdog/exception resets, includes detailed exception info
+static const char *get_reset_info_str(std::span<char, RESET_INFO_BUFFER_SIZE> buffer, uint32_t reason) {
+  if (reason >= REASON_WDT_RST && reason <= REASON_SOFT_WDT_RST) {
+    snprintf_P(buffer.data(), RESET_INFO_BUFFER_SIZE,
+               PSTR("Fatal exception:%d flag:%d (%s) epc1:0x%08x epc2:0x%08x epc3:0x%08x excvaddr:0x%08x depc:0x%08x"),
+               static_cast<int>(resetInfo.exccause), static_cast<int>(reason),
+               LOG_STR_ARG(get_reset_reason_str(reason)), resetInfo.epc1, resetInfo.epc2, resetInfo.epc3,
+               resetInfo.excvaddr, resetInfo.depc);
+    return buffer.data();
+  }
+  return LOG_STR_ARG(get_reset_reason_str(reason));
+}
+
 const char *DebugComponent::get_reset_reason_(std::span<char, RESET_REASON_BUFFER_SIZE> buffer) {
-  char *buf = buffer.data();
-#if !defined(CLANG_TIDY)
-  String reason = ESP.getResetReason();  // NOLINT
-  snprintf_P(buf, RESET_REASON_BUFFER_SIZE, PSTR("%s"), reason.c_str());
-  return buf;
-#else
-  buf[0] = '\0';
-  return buf;
-#endif
+  // Copy from flash to provided buffer
+  strncpy_P(buffer.data(), (PGM_P) get_reset_reason_str(resetInfo.reason), RESET_REASON_BUFFER_SIZE - 1);
+  buffer[RESET_REASON_BUFFER_SIZE - 1] = '\0';
+  return buffer.data();
 }
 
 const char *DebugComponent::get_wakeup_cause_(std::span<char, RESET_REASON_BUFFER_SIZE> buffer) {
@@ -33,37 +92,42 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
   constexpr size_t size = DEVICE_INFO_BUFFER_SIZE;
   char *buf = buffer.data();
 
-  const char *flash_mode;
+  const LogString *flash_mode;
   switch (ESP.getFlashChipMode()) {  // NOLINT(readability-static-accessed-through-instance)
     case FM_QIO:
-      flash_mode = "QIO";
+      flash_mode = LOG_STR("QIO");
       break;
     case FM_QOUT:
-      flash_mode = "QOUT";
+      flash_mode = LOG_STR("QOUT");
       break;
     case FM_DIO:
-      flash_mode = "DIO";
+      flash_mode = LOG_STR("DIO");
       break;
     case FM_DOUT:
-      flash_mode = "DOUT";
+      flash_mode = LOG_STR("DOUT");
       break;
     default:
-      flash_mode = "UNKNOWN";
+      flash_mode = LOG_STR("UNKNOWN");
   }
-  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);
+  uint32_t flash_size = ESP.getFlashChipSize() / 1024;       // NOLINT(readability-static-accessed-through-instance)
+  uint32_t flash_speed = ESP.getFlashChipSpeed() / 1000000;  // NOLINT(readability-static-accessed-through-instance)
+  ESP_LOGD(TAG, "Flash Chip: Size=%" PRIu32 "kB Speed=%" PRIu32 "MHz Mode=%s", flash_size, flash_speed,
+           LOG_STR_ARG(flash_mode));
+  pos = buf_append_printf(buf, size, pos, "|Flash: %" PRIu32 "kB Speed:%" PRIu32 "MHz Mode:%s", flash_size, flash_speed,
+                          LOG_STR_ARG(flash_mode));
 
-#if !defined(CLANG_TIDY)
   char reason_buffer[RESET_REASON_BUFFER_SIZE];
-  const char *reset_reason = get_reset_reason_(std::span<char, RESET_REASON_BUFFER_SIZE>(reason_buffer));
+  const char *reset_reason = get_reset_reason_(reason_buffer);
+  char core_version_buffer[CORE_VERSION_BUFFER_SIZE];
+  char reset_info_buffer[RESET_INFO_BUFFER_SIZE];
+  // NOLINTBEGIN(readability-static-accessed-through-instance)
   uint32_t chip_id = ESP.getChipId();
   uint8_t boot_version = ESP.getBootVersion();
   uint8_t boot_mode = ESP.getBootMode();
   uint8_t cpu_freq = ESP.getCpuFreqMHz();
   uint32_t flash_chip_id = ESP.getFlashChipId();
+  const char *sdk_version = ESP.getSdkVersion();
+  // NOLINTEND(readability-static-accessed-through-instance)
 
   ESP_LOGD(TAG,
            "Chip ID: 0x%08" PRIX32 "\n"
@@ -74,19 +138,18 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
            "Flash Chip ID=0x%08" PRIX32 "\n"
            "Reset Reason: %s\n"
            "Reset Info: %s",
-           chip_id, ESP.getSdkVersion(), ESP.getCoreVersion().c_str(), boot_version, boot_mode, cpu_freq, flash_chip_id,
-           reset_reason, ESP.getResetInfo().c_str());
+           chip_id, sdk_version, get_core_version_str(core_version_buffer), boot_version, boot_mode, cpu_freq,
+           flash_chip_id, reset_reason, get_reset_info_str(reset_info_buffer, resetInfo.reason));
 
-  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());
-#endif
+  pos = buf_append_printf(buf, size, pos, "|Chip: 0x%08" PRIX32, chip_id);
+  pos = buf_append_printf(buf, size, pos, "|SDK: %s", sdk_version);
+  pos = buf_append_printf(buf, size, pos, "|Core: %s", get_core_version_str(core_version_buffer));
+  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", get_reset_info_str(reset_info_buffer, resetInfo.reason));
 
   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) {
@@ -132,6 +132,26 @@ void DebugComponent::log_partition_info_() {
   flash_area_foreach(fa_cb, nullptr);
 }
 
+static const char *regout0_to_str(uint32_t value) {
+  switch (value) {
+    case (UICR_REGOUT0_VOUT_DEFAULT):
+      return "1.8V (default)";
+    case (UICR_REGOUT0_VOUT_1V8):
+      return "1.8V";
+    case (UICR_REGOUT0_VOUT_2V1):
+      return "2.1V";
+    case (UICR_REGOUT0_VOUT_2V4):
+      return "2.4V";
+    case (UICR_REGOUT0_VOUT_2V7):
+      return "2.7V";
+    case (UICR_REGOUT0_VOUT_3V0):
+      return "3.0V";
+    case (UICR_REGOUT0_VOUT_3V3):
+      return "3.3V";
+  }
+  return "???V";
+}
+
 size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE> buffer, size_t pos) {
   constexpr size_t size = DEVICE_INFO_BUFFER_SIZE;
   char *buf = buffer.data();
@@ -140,48 +160,28 @@ 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) {
     const char *reg0_type = nrf_power_dcdcen_vddh_get(NRF_POWER) ? "DC/DC" : "LDO";
-    const char *reg0_voltage;
-    switch (NRF_UICR->REGOUT0 & UICR_REGOUT0_VOUT_Msk) {
-      case (UICR_REGOUT0_VOUT_DEFAULT << UICR_REGOUT0_VOUT_Pos):
-        reg0_voltage = "1.8V (default)";
-        break;
-      case (UICR_REGOUT0_VOUT_1V8 << UICR_REGOUT0_VOUT_Pos):
-        reg0_voltage = "1.8V";
-        break;
-      case (UICR_REGOUT0_VOUT_2V1 << UICR_REGOUT0_VOUT_Pos):
-        reg0_voltage = "2.1V";
-        break;
-      case (UICR_REGOUT0_VOUT_2V4 << UICR_REGOUT0_VOUT_Pos):
-        reg0_voltage = "2.4V";
-        break;
-      case (UICR_REGOUT0_VOUT_2V7 << UICR_REGOUT0_VOUT_Pos):
-        reg0_voltage = "2.7V";
-        break;
-      case (UICR_REGOUT0_VOUT_3V0 << UICR_REGOUT0_VOUT_Pos):
-        reg0_voltage = "3.0V";
-        break;
-      case (UICR_REGOUT0_VOUT_3V3 << UICR_REGOUT0_VOUT_Pos):
-        reg0_voltage = "3.3V";
-        break;
-      default:
-        reg0_voltage = "???V";
-    }
+    const char *reg0_voltage = regout0_to_str((NRF_UICR->REGOUT0 & UICR_REGOUT0_VOUT_Msk) >> UICR_REGOUT0_VOUT_Pos);
     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);
+#ifdef USE_NRF52_REG0_VOUT
+    if ((NRF_UICR->REGOUT0 & UICR_REGOUT0_VOUT_Msk) >> UICR_REGOUT0_VOUT_Pos != USE_NRF52_REG0_VOUT) {
+      ESP_LOGE(TAG, "Regulator stage 0: expected %s", regout0_to_str(USE_NRF52_REG0_VOUT));
+    }
+#endif
   } 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.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/dsmr/__init__.py

@@ -25,29 +25,13 @@ dsmr_ns = cg.esphome_ns.namespace("esphome::dsmr")
 Dsmr = dsmr_ns.class_("Dsmr", cg.Component, uart.UARTDevice)
 
 
-def _validate_key(value):
-    value = cv.string_strict(value)
-    parts = [value[i : i + 2] for i in range(0, len(value), 2)]
-    if len(parts) != 16:
-        raise cv.Invalid("Decryption key must consist of 16 hexadecimal numbers")
-    parts_int = []
-    if any(len(part) != 2 for part in parts):
-        raise cv.Invalid("Decryption key must be format XX")
-    for part in parts:
-        try:
-            parts_int.append(int(part, 16))
-        except ValueError:
-            # pylint: disable=raise-missing-from
-            raise cv.Invalid("Decryption key must be hex values from 00 to FF")
-
-    return "".join(f"{part:02X}" for part in parts_int)
-
-
 CONFIG_SCHEMA = cv.All(
     cv.Schema(
         {
             cv.GenerateID(): cv.declare_id(Dsmr),
-            cv.Optional(CONF_DECRYPTION_KEY): _validate_key,
+            cv.Optional(CONF_DECRYPTION_KEY): lambda value: cv.bind_key(
+                value, name="Decryption key"
+            ),
             cv.Optional(CONF_CRC_CHECK, default=True): cv.boolean,
             cv.Optional(CONF_GAS_MBUS_ID, default=1): cv.int_,
             cv.Optional(CONF_WATER_MBUS_ID, default=2): cv.int_,

esphome/components/dsmr/dsmr.cpp

@@ -1,4 +1,5 @@
 #include "dsmr.h"
+#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
 #include <AES.h>
@@ -294,8 +295,8 @@ void Dsmr::dump_config() {
   DSMR_TEXT_SENSOR_LIST(DSMR_LOG_TEXT_SENSOR, )
 }
 
-void Dsmr::set_decryption_key(const std::string &decryption_key) {
-  if (decryption_key.empty()) {
+void Dsmr::set_decryption_key(const char *decryption_key) {
+  if (decryption_key == nullptr || decryption_key[0] == '\0') {
     ESP_LOGI(TAG, "Disabling decryption");
     this->decryption_key_.clear();
     if (this->crypt_telegram_ != nullptr) {
@@ -305,21 +306,15 @@ void Dsmr::set_decryption_key(const std::string &decryption_key) {
     return;
   }
 
-  if (decryption_key.length() != 32) {
-    ESP_LOGE(TAG, "Error, decryption key must be 32 character long");
+  if (!parse_hex(decryption_key, this->decryption_key_, 16)) {
+    ESP_LOGE(TAG, "Error, decryption key must be 32 hex characters");
+    this->decryption_key_.clear();
     return;
   }
-  this->decryption_key_.clear();
 
   ESP_LOGI(TAG, "Decryption key is set");
   // Verbose level prints decryption key
-  ESP_LOGV(TAG, "Using decryption key: %s", decryption_key.c_str());
-
-  char temp[3] = {0};
-  for (int i = 0; i < 16; i++) {
-    strncpy(temp, &(decryption_key.c_str()[i * 2]), 2);
-    this->decryption_key_.push_back(std::strtoul(temp, nullptr, 16));
-  }
+  ESP_LOGV(TAG, "Using decryption key: %s", decryption_key);
 
   if (this->crypt_telegram_ == nullptr) {
     this->crypt_telegram_ = new uint8_t[this->max_telegram_len_];  // NOLINT

esphome/components/dsmr/dsmr.h

@@ -63,7 +63,7 @@ class Dsmr : public Component, public uart::UARTDevice {
 
   void dump_config() override;
 
-  void set_decryption_key(const std::string &decryption_key);
+  void set_decryption_key(const char *decryption_key);
   void set_max_telegram_length(size_t length) { this->max_telegram_len_ = length; }
   void set_request_pin(GPIOPin *request_pin) { this->request_pin_ = request_pin; }
   void set_request_interval(uint32_t interval) { this->request_interval_ = interval; }

esphome/components/epaper_spi/display.py

@@ -190,7 +190,7 @@ async def to_code(config):
     # Rotation is handled by setting the transform
     display_config = {k: v for k, v in config.items() if k != CONF_ROTATION}
     await display.register_display(var, display_config)
-    await spi.register_spi_device(var, config)
+    await spi.register_spi_device(var, config, write_only=True)
 
     dc = await cg.gpio_pin_expression(config[CONF_DC_PIN])
     cg.add(var.set_dc_pin(dc))

esphome/components/esp32/__init__.py

@@ -34,6 +34,7 @@ from esphome.const import (
     KEY_CORE,
     KEY_FRAMEWORK_VERSION,
     KEY_NAME,
+    KEY_NATIVE_IDF,
     KEY_TARGET_FRAMEWORK,
     KEY_TARGET_PLATFORM,
     PLATFORM_ESP32,
@@ -53,6 +54,7 @@ from .const import (  # noqa
     KEY_COMPONENTS,
     KEY_ESP32,
     KEY_EXTRA_BUILD_FILES,
+    KEY_FLASH_SIZE,
     KEY_PATH,
     KEY_REF,
     KEY_REPO,
@@ -180,6 +182,12 @@ def set_core_data(config):
             path=[CONF_CPU_FREQUENCY],
         )
 
+    if variant == VARIANT_ESP32P4 and cpu_frequency == "400MHZ":
+        _LOGGER.warning(
+            "400MHz on ESP32-P4 is experimental and may not boot. "
+            "Consider using 360MHz instead. See https://github.com/esphome/esphome/issues/13425"
+        )
+
     CORE.data[KEY_ESP32] = {}
     CORE.data[KEY_CORE][KEY_TARGET_PLATFORM] = PLATFORM_ESP32
     conf = config[CONF_FRAMEWORK]
@@ -199,6 +207,7 @@ def set_core_data(config):
     )
 
     CORE.data[KEY_ESP32][KEY_BOARD] = config[CONF_BOARD]
+    CORE.data[KEY_ESP32][KEY_FLASH_SIZE] = config[CONF_FLASH_SIZE]
     CORE.data[KEY_ESP32][KEY_VARIANT] = variant
     CORE.data[KEY_ESP32][KEY_EXTRA_BUILD_FILES] = {}
 
@@ -339,7 +348,12 @@ def add_extra_build_file(filename: str, path: Path) -> bool:
 def _format_framework_arduino_version(ver: cv.Version) -> str:
     # format the given arduino (https://github.com/espressif/arduino-esp32/releases) version to
     # a PIO pioarduino/framework-arduinoespressif32 value
-    return f"pioarduino/framework-arduinoespressif32@https://github.com/espressif/arduino-esp32/releases/download/{str(ver)}/esp32-{str(ver)}.zip"
+    # 3.3.6+ changed filename from esp32-{ver}.zip to esp32-core-{ver}.tar.xz
+    if ver >= cv.Version(3, 3, 6):
+        filename = f"esp32-core-{ver}.tar.xz"
+    else:
+        filename = f"esp32-{ver}.zip"
+    return f"pioarduino/framework-arduinoespressif32@https://github.com/espressif/arduino-esp32/releases/download/{ver}/{filename}"
 
 
 def _format_framework_espidf_version(ver: cv.Version, release: str) -> str:
@@ -374,11 +388,12 @@ def _is_framework_url(source: str) -> bool:
 # The default/recommended arduino framework version
 #  - https://github.com/espressif/arduino-esp32/releases
 ARDUINO_FRAMEWORK_VERSION_LOOKUP = {
-    "recommended": cv.Version(3, 3, 5),
-    "latest": cv.Version(3, 3, 5),
-    "dev": cv.Version(3, 3, 5),
+    "recommended": cv.Version(3, 3, 6),
+    "latest": cv.Version(3, 3, 6),
+    "dev": cv.Version(3, 3, 6),
 }
 ARDUINO_PLATFORM_VERSION_LOOKUP = {
+    cv.Version(3, 3, 6): cv.Version(55, 3, 36),
     cv.Version(3, 3, 5): cv.Version(55, 3, 35),
     cv.Version(3, 3, 4): cv.Version(55, 3, 31, "2"),
     cv.Version(3, 3, 3): cv.Version(55, 3, 31, "2"),
@@ -396,6 +411,7 @@ ARDUINO_PLATFORM_VERSION_LOOKUP = {
 # These versions correspond to pioarduino/esp-idf releases
 # See: https://github.com/pioarduino/esp-idf/releases
 ARDUINO_IDF_VERSION_LOOKUP = {
+    cv.Version(3, 3, 6): cv.Version(5, 5, 2),
     cv.Version(3, 3, 5): cv.Version(5, 5, 2),
     cv.Version(3, 3, 4): cv.Version(5, 5, 1),
     cv.Version(3, 3, 3): cv.Version(5, 5, 1),
@@ -418,7 +434,7 @@ ESP_IDF_FRAMEWORK_VERSION_LOOKUP = {
     "dev": cv.Version(5, 5, 2),
 }
 ESP_IDF_PLATFORM_VERSION_LOOKUP = {
-    cv.Version(5, 5, 2): cv.Version(55, 3, 35),
+    cv.Version(5, 5, 2): cv.Version(55, 3, 36),
     cv.Version(5, 5, 1): cv.Version(55, 3, 31, "2"),
     cv.Version(5, 5, 0): cv.Version(55, 3, 31, "2"),
     cv.Version(5, 4, 3): cv.Version(55, 3, 32),
@@ -435,9 +451,9 @@ ESP_IDF_PLATFORM_VERSION_LOOKUP = {
 # The platform-espressif32 version
 #  - https://github.com/pioarduino/platform-espressif32/releases
 PLATFORM_VERSION_LOOKUP = {
-    "recommended": cv.Version(55, 3, 35),
-    "latest": cv.Version(55, 3, 35),
-    "dev": cv.Version(55, 3, 35),
+    "recommended": cv.Version(55, 3, 36),
+    "latest": cv.Version(55, 3, 36),
+    "dev": cv.Version(55, 3, 36),
 }
 
 
@@ -962,12 +978,54 @@ async def _add_yaml_idf_components(components: list[ConfigType]):
 
 
 async def to_code(config):
-    cg.add_platformio_option("board", config[CONF_BOARD])
-    cg.add_platformio_option("board_upload.flash_size", config[CONF_FLASH_SIZE])
-    cg.add_platformio_option(
-        "board_upload.maximum_size",
-        int(config[CONF_FLASH_SIZE].removesuffix("MB")) * 1024 * 1024,
-    )
+    framework_ver: cv.Version = CORE.data[KEY_CORE][KEY_FRAMEWORK_VERSION]
+    conf = config[CONF_FRAMEWORK]
+
+    # Check if using native ESP-IDF build (--native-idf)
+    use_platformio = not CORE.data.get(KEY_NATIVE_IDF, False)
+    if use_platformio:
+        # Clear IDF environment variables to avoid conflicts with PlatformIO's ESP-IDF
+        # but keep them when using --native-idf for native ESP-IDF builds
+        for clean_var in ("IDF_PATH", "IDF_TOOLS_PATH"):
+            os.environ.pop(clean_var, None)
+
+        cg.add_platformio_option("lib_ldf_mode", "off")
+        cg.add_platformio_option("lib_compat_mode", "strict")
+        cg.add_platformio_option("platform", conf[CONF_PLATFORM_VERSION])
+        cg.add_platformio_option("board", config[CONF_BOARD])
+        cg.add_platformio_option("board_upload.flash_size", config[CONF_FLASH_SIZE])
+        cg.add_platformio_option(
+            "board_upload.maximum_size",
+            int(config[CONF_FLASH_SIZE].removesuffix("MB")) * 1024 * 1024,
+        )
+
+        if CONF_SOURCE in conf:
+            cg.add_platformio_option("platform_packages", [conf[CONF_SOURCE]])
+
+        add_extra_script(
+            "pre",
+            "pre_build.py",
+            Path(__file__).parent / "pre_build.py.script",
+        )
+
+        add_extra_script(
+            "post",
+            "post_build.py",
+            Path(__file__).parent / "post_build.py.script",
+        )
+
+        # In testing mode, add IRAM fix script to allow linking grouped component tests
+        # Similar to ESP8266's approach but for ESP-IDF
+        if CORE.testing_mode:
+            cg.add_build_flag("-DESPHOME_TESTING_MODE")
+            add_extra_script(
+                "pre",
+                "iram_fix.py",
+                Path(__file__).parent / "iram_fix.py.script",
+            )
+    else:
+        cg.add_build_flag("-Wno-error=format")
+
     cg.set_cpp_standard("gnu++20")
     cg.add_build_flag("-DUSE_ESP32")
     cg.add_build_flag("-Wl,-z,noexecstack")
@@ -977,79 +1035,49 @@ async def to_code(config):
     cg.add_define("ESPHOME_VARIANT", VARIANT_FRIENDLY[variant])
     cg.add_define(ThreadModel.MULTI_ATOMICS)
 
-    cg.add_platformio_option("lib_ldf_mode", "off")
-    cg.add_platformio_option("lib_compat_mode", "strict")
-
-    framework_ver: cv.Version = CORE.data[KEY_CORE][KEY_FRAMEWORK_VERSION]
-
-    conf = config[CONF_FRAMEWORK]
-    cg.add_platformio_option("platform", conf[CONF_PLATFORM_VERSION])
-    if CONF_SOURCE in conf:
-        cg.add_platformio_option("platform_packages", [conf[CONF_SOURCE]])
-
     if conf[CONF_ADVANCED][CONF_IGNORE_EFUSE_CUSTOM_MAC]:
         cg.add_define("USE_ESP32_IGNORE_EFUSE_CUSTOM_MAC")
 
-    for clean_var in ("IDF_PATH", "IDF_TOOLS_PATH"):
-        os.environ.pop(clean_var, None)
-
     # Set the location of the IDF component manager cache
     os.environ["IDF_COMPONENT_CACHE_PATH"] = str(
         CORE.relative_internal_path(".espressif")
     )
 
-    add_extra_script(
-        "pre",
-        "pre_build.py",
-        Path(__file__).parent / "pre_build.py.script",
-    )
-
-    add_extra_script(
-        "post",
-        "post_build.py",
-        Path(__file__).parent / "post_build.py.script",
-    )
-
-    # In testing mode, add IRAM fix script to allow linking grouped component tests
-    # Similar to ESP8266's approach but for ESP-IDF
-    if CORE.testing_mode:
-        cg.add_build_flag("-DESPHOME_TESTING_MODE")
-        add_extra_script(
-            "pre",
-            "iram_fix.py",
-            Path(__file__).parent / "iram_fix.py.script",
-        )
-
     if conf[CONF_TYPE] == FRAMEWORK_ESP_IDF:
-        cg.add_platformio_option("framework", "espidf")
         cg.add_build_flag("-DUSE_ESP_IDF")
         cg.add_build_flag("-DUSE_ESP32_FRAMEWORK_ESP_IDF")
+        if use_platformio:
+            cg.add_platformio_option("framework", "espidf")
     else:
-        cg.add_platformio_option("framework", "arduino, espidf")
         cg.add_build_flag("-DUSE_ARDUINO")
         cg.add_build_flag("-DUSE_ESP32_FRAMEWORK_ARDUINO")
+        if use_platformio:
+            cg.add_platformio_option("framework", "arduino, espidf")
+
+            # Add IDF framework source for Arduino builds to ensure it uses the same version as
+            # the ESP-IDF framework
+            if (idf_ver := ARDUINO_IDF_VERSION_LOOKUP.get(framework_ver)) is not None:
+                cg.add_platformio_option(
+                    "platform_packages",
+                    [_format_framework_espidf_version(idf_ver, None)],
+                )
+
+            # ESP32-S2 Arduino: Disable USB Serial on boot to avoid TinyUSB dependency
+            if get_esp32_variant() == VARIANT_ESP32S2:
+                cg.add_build_unflag("-DARDUINO_USB_CDC_ON_BOOT=1")
+                cg.add_build_unflag("-DARDUINO_USB_CDC_ON_BOOT=0")
+                cg.add_build_flag("-DARDUINO_USB_CDC_ON_BOOT=0")
+
         cg.add_define(
             "USE_ARDUINO_VERSION_CODE",
             cg.RawExpression(
                 f"VERSION_CODE({framework_ver.major}, {framework_ver.minor}, {framework_ver.patch})"
             ),
         )
+
         add_idf_sdkconfig_option("CONFIG_MBEDTLS_PSK_MODES", True)
         add_idf_sdkconfig_option("CONFIG_MBEDTLS_CERTIFICATE_BUNDLE", True)
 
-        # Add IDF framework source for Arduino builds to ensure it uses the same version as
-        # the ESP-IDF framework
-        if (idf_ver := ARDUINO_IDF_VERSION_LOOKUP.get(framework_ver)) is not None:
-            cg.add_platformio_option(
-                "platform_packages", [_format_framework_espidf_version(idf_ver, None)]
-            )
-
-        # ESP32-S2 Arduino: Disable USB Serial on boot to avoid TinyUSB dependency
-        if get_esp32_variant() == VARIANT_ESP32S2:
-            cg.add_build_unflag("-DARDUINO_USB_CDC_ON_BOOT=1")
-            cg.add_build_unflag("-DARDUINO_USB_CDC_ON_BOOT=0")
-            cg.add_build_flag("-DARDUINO_USB_CDC_ON_BOOT=0")
-
     cg.add_build_flag("-Wno-nonnull-compare")
 
     add_idf_sdkconfig_option(f"CONFIG_IDF_TARGET_{variant}", True)
@@ -1196,7 +1224,8 @@ async def to_code(config):
             "CONFIG_VFS_SUPPORT_DIR", not advanced[CONF_DISABLE_VFS_SUPPORT_DIR]
         )
 
-    cg.add_platformio_option("board_build.partitions", "partitions.csv")
+    if use_platformio:
+        cg.add_platformio_option("board_build.partitions", "partitions.csv")
     if CONF_PARTITIONS in config:
         add_extra_build_file(
             "partitions.csv", CORE.relative_config_path(config[CONF_PARTITIONS])
@@ -1361,19 +1390,16 @@ def copy_files():
     _write_idf_component_yml()
 
     if "partitions.csv" not in CORE.data[KEY_ESP32][KEY_EXTRA_BUILD_FILES]:
+        flash_size = CORE.data[KEY_ESP32][KEY_FLASH_SIZE]
         if CORE.using_arduino:
             write_file_if_changed(
                 CORE.relative_build_path("partitions.csv"),
-                get_arduino_partition_csv(
-                    CORE.platformio_options.get("board_upload.flash_size")
-                ),
+                get_arduino_partition_csv(flash_size),
             )
         else:
             write_file_if_changed(
                 CORE.relative_build_path("partitions.csv"),
-                get_idf_partition_csv(
-                    CORE.platformio_options.get("board_upload.flash_size")
-                ),
+                get_idf_partition_csv(flash_size),
             )
     # IDF build scripts look for version string to put in the build.
     # However, if the build path does not have an initialized git repo,

esphome/components/esp32/const.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 
 KEY_ESP32 = "esp32"
 KEY_BOARD = "board"
+KEY_FLASH_SIZE = "flash_size"
 KEY_VARIANT = "variant"
 KEY_SDKCONFIG_OPTIONS = "sdkconfig_options"
 KEY_COMPONENTS = "components"

esphome/components/esp32/preferences.cpp

@@ -181,7 +181,8 @@ class ESP32Preferences : public ESPPreferences {
     if (actual_len != to_save.len) {
       return true;
     }
-    auto stored_data = std::make_unique<uint8_t[]>(actual_len);
+    // Most preferences are small, use stack buffer with heap fallback for large ones
+    SmallBufferWithHeapFallback<256> stored_data(actual_len);
     err = nvs_get_blob(nvs_handle, key_str, stored_data.get(), &actual_len);
     if (err != 0) {
       ESP_LOGV(TAG, "nvs_get_blob('%s') failed: %s", key_str, esp_err_to_name(err));

esphome/components/esp32_ble/ble_uuid.h

@@ -46,6 +46,8 @@ class ESPBTUUID {
 
   esp_bt_uuid_t get_uuid() const;
 
+  // Remove before 2026.8.0
+  ESPDEPRECATED("Use to_str() instead. Removed in 2026.8.0", "2026.2.0")
   std::string to_string() const;
   const char *to_str(std::span<char, UUID_STR_LEN> output) const;
 

esphome/components/esp32_ble_client/ble_client_base.cpp

@@ -50,7 +50,7 @@ void BLEClientBase::loop() {
     this->set_state(espbt::ClientState::INIT);
     return;
   }
-  if (this->state_ == espbt::ClientState::INIT) {
+  if (this->state() == espbt::ClientState::INIT) {
     auto ret = esp_ble_gattc_app_register(this->app_id);
     if (ret) {
       ESP_LOGE(TAG, "gattc app register failed. app_id=%d code=%d", this->app_id, ret);
@@ -60,7 +60,7 @@ void BLEClientBase::loop() {
   }
   // If idle, we can disable the loop as connect()
   // will enable it again when a connection is needed.
-  else if (this->state_ == espbt::ClientState::IDLE) {
+  else if (this->state() == espbt::ClientState::IDLE) {
     this->disable_loop();
   }
 }
@@ -86,7 +86,7 @@ bool BLEClientBase::parse_device(const espbt::ESPBTDevice &device) {
     return false;
   if (this->address_ == 0 || device.address_uint64() != this->address_)
     return false;
-  if (this->state_ != espbt::ClientState::IDLE)
+  if (this->state() != espbt::ClientState::IDLE)
     return false;
 
   this->log_event_("Found device");
@@ -102,10 +102,10 @@ bool BLEClientBase::parse_device(const espbt::ESPBTDevice &device) {
 
 void BLEClientBase::connect() {
   // Prevent duplicate connection attempts
-  if (this->state_ == espbt::ClientState::CONNECTING || this->state_ == espbt::ClientState::CONNECTED ||
-      this->state_ == espbt::ClientState::ESTABLISHED) {
+  if (this->state() == espbt::ClientState::CONNECTING || this->state() == espbt::ClientState::CONNECTED ||
+      this->state() == espbt::ClientState::ESTABLISHED) {
     ESP_LOGW(TAG, "[%d] [%s] Connection already in progress, state=%s", this->connection_index_, this->address_str_,
-             espbt::client_state_to_string(this->state_));
+             espbt::client_state_to_string(this->state()));
     return;
   }
   ESP_LOGI(TAG, "[%d] [%s] 0x%02x Connecting", this->connection_index_, this->address_str_, this->remote_addr_type_);
@@ -133,12 +133,12 @@ void BLEClientBase::connect() {
 esp_err_t BLEClientBase::pair() { return esp_ble_set_encryption(this->remote_bda_, ESP_BLE_SEC_ENCRYPT); }
 
 void BLEClientBase::disconnect() {
-  if (this->state_ == espbt::ClientState::IDLE || this->state_ == espbt::ClientState::DISCONNECTING) {
+  if (this->state() == espbt::ClientState::IDLE || this->state() == espbt::ClientState::DISCONNECTING) {
     ESP_LOGI(TAG, "[%d] [%s] Disconnect requested, but already %s", this->connection_index_, this->address_str_,
-             espbt::client_state_to_string(this->state_));
+             espbt::client_state_to_string(this->state()));
     return;
   }
-  if (this->state_ == espbt::ClientState::CONNECTING || this->conn_id_ == UNSET_CONN_ID) {
+  if (this->state() == espbt::ClientState::CONNECTING || this->conn_id_ == UNSET_CONN_ID) {
     ESP_LOGD(TAG, "[%d] [%s] Disconnect before connected, disconnect scheduled", this->connection_index_,
              this->address_str_);
     this->want_disconnect_ = true;
@@ -150,7 +150,7 @@ void BLEClientBase::disconnect() {
 void BLEClientBase::unconditional_disconnect() {
   // Disconnect without checking the state.
   ESP_LOGI(TAG, "[%d] [%s] Disconnecting (conn_id: %d).", this->connection_index_, this->address_str_, this->conn_id_);
-  if (this->state_ == espbt::ClientState::DISCONNECTING) {
+  if (this->state() == espbt::ClientState::DISCONNECTING) {
     this->log_error_("Already disconnecting");
     return;
   }
@@ -170,7 +170,7 @@ void BLEClientBase::unconditional_disconnect() {
     this->log_gattc_warning_("esp_ble_gattc_close", err);
   }
 
-  if (this->state_ == espbt::ClientState::DISCOVERED) {
+  if (this->state() == espbt::ClientState::DISCOVERED) {
     this->set_address(0);
     this->set_state(espbt::ClientState::IDLE);
   } else {
@@ -295,18 +295,18 @@ bool BLEClientBase::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_
       // ESP-IDF's BLE stack may send ESP_GATTC_OPEN_EVT after esp_ble_gattc_open() returns an
       // error, if the error occurred at the BTA/GATT layer. This can result in the event
       // arriving after we've already transitioned to IDLE state.
-      if (this->state_ == espbt::ClientState::IDLE) {
+      if (this->state() == espbt::ClientState::IDLE) {
         ESP_LOGD(TAG, "[%d] [%s] ESP_GATTC_OPEN_EVT in IDLE state (status=%d), ignoring", this->connection_index_,
                  this->address_str_, param->open.status);
         break;
       }
 
-      if (this->state_ != espbt::ClientState::CONNECTING) {
+      if (this->state() != espbt::ClientState::CONNECTING) {
         // This should not happen but lets log it in case it does
         // because it means we have a bad assumption about how the
         // ESP BT stack works.
         ESP_LOGE(TAG, "[%d] [%s] ESP_GATTC_OPEN_EVT in %s state (status=%d)", this->connection_index_,
-                 this->address_str_, espbt::client_state_to_string(this->state_), param->open.status);
+                 this->address_str_, espbt::client_state_to_string(this->state()), param->open.status);
       }
       if (param->open.status != ESP_GATT_OK && param->open.status != ESP_GATT_ALREADY_OPEN) {
         this->log_gattc_warning_("Connection open", param->open.status);
@@ -327,7 +327,7 @@ bool BLEClientBase::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_
       if (this->connection_type_ == espbt::ConnectionType::V3_WITH_CACHE) {
         // Cached connections already connected with medium parameters, no update needed
         // only set our state, subclients might have more stuff to do yet.
-        this->state_ = espbt::ClientState::ESTABLISHED;
+        this->set_state_internal_(espbt::ClientState::ESTABLISHED);
         break;
       }
       // For V3_WITHOUT_CACHE, we already set fast params before connecting
@@ -356,7 +356,7 @@ bool BLEClientBase::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_
         return false;
       // Check if we were disconnected while waiting for service discovery
       if (param->disconnect.reason == ESP_GATT_CONN_TERMINATE_PEER_USER &&
-          this->state_ == espbt::ClientState::CONNECTED) {
+          this->state() == espbt::ClientState::CONNECTED) {
         this->log_warning_("Remote closed during discovery");
       } else {
         ESP_LOGD(TAG, "[%d] [%s] ESP_GATTC_DISCONNECT_EVT, reason 0x%02x", this->connection_index_, this->address_str_,
@@ -433,7 +433,7 @@ bool BLEClientBase::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_
 #endif
       }
       ESP_LOGI(TAG, "[%d] [%s] Service discovery complete", this->connection_index_, this->address_str_);
-      this->state_ = espbt::ClientState::ESTABLISHED;
+      this->set_state_internal_(espbt::ClientState::ESTABLISHED);
       break;
     }
     case ESP_GATTC_READ_DESCR_EVT: {

esphome/components/esp32_ble_client/ble_client_base.h

@@ -44,7 +44,7 @@ class BLEClientBase : public espbt::ESPBTClient, public Component {
   void unconditional_disconnect();
   void release_services();
 
-  bool connected() { return this->state_ == espbt::ClientState::ESTABLISHED; }
+  bool connected() { return this->state() == espbt::ClientState::ESTABLISHED; }
 
   void set_auto_connect(bool auto_connect) { this->auto_connect_ = auto_connect; }
 

esphome/components/esp32_ble_tracker/esp32_ble_tracker.cpp

@@ -105,15 +105,13 @@ void ESP32BLETracker::loop() {
   }
 
   // Check for scan timeout - moved here from scheduler to avoid false reboots
-  // when the loop is blocked
+  // when the loop is blocked. This must run every iteration for safety.
   if (this->scanner_state_ == ScannerState::RUNNING) {
     switch (this->scan_timeout_state_) {
       case ScanTimeoutState::MONITORING: {
-        uint32_t now = App.get_loop_component_start_time();
-        uint32_t timeout_ms = this->scan_duration_ * 2000;
         // Robust time comparison that handles rollover correctly
         // This works because unsigned arithmetic wraps around predictably
-        if ((now - this->scan_start_time_) > timeout_ms) {
+        if ((App.get_loop_component_start_time() - this->scan_start_time_) > this->scan_timeout_ms_) {
           // First time we've seen the timeout exceeded - wait one more loop iteration
           // This ensures all components have had a chance to process pending events
           // This is because esp32_ble may not have run yet and called
@@ -128,13 +126,31 @@ void ESP32BLETracker::loop() {
         ESP_LOGE(TAG, "Scan never terminated, rebooting");
         App.reboot();
         break;
-
       case ScanTimeoutState::INACTIVE:
-        // This case should be unreachable - scanner and timeout states are always synchronized
         break;
     }
   }
 
+  // Fast path: skip expensive client state counting and processing
+  // if no state has changed since last loop iteration.
+  //
+  // How state changes ensure we reach the code below:
+  // - handle_scanner_failure_(): scanner_state_ becomes FAILED via set_scanner_state_(), or
+  //   scan_set_param_failed_ requires scanner_state_==RUNNING which can only be reached via
+  //   set_scanner_state_(RUNNING) in gap_scan_start_complete_() (scan params are set during
+  //   STARTING, not RUNNING, so version is always incremented before this condition is true)
+  // - start_scan_(): scanner_state_ becomes IDLE via set_scanner_state_() in cleanup_scan_state_()
+  // - try_promote_discovered_clients_(): client enters DISCOVERED via set_state(), or
+  //   connecting client finishes (state change), or scanner reaches RUNNING/IDLE
+  //
+  // All conditions that affect the logic below are tied to state changes that increment
+  // state_version_, so the fast path is safe.
+  if (this->state_version_ == this->last_processed_version_) {
+    return;
+  }
+  this->last_processed_version_ = this->state_version_;
+
+  // State changed - do full processing
   ClientStateCounts counts = this->count_client_states_();
   if (counts != this->client_state_counts_) {
     this->client_state_counts_ = counts;
@@ -142,6 +158,7 @@ void ESP32BLETracker::loop() {
              this->client_state_counts_.discovered, this->client_state_counts_.disconnecting);
   }
 
+  // Scanner failure: reached when set_scanner_state_(FAILED) or scan_set_param_failed_ set
   if (this->scanner_state_ == ScannerState::FAILED ||
       (this->scan_set_param_failed_ && this->scanner_state_ == ScannerState::RUNNING)) {
     this->handle_scanner_failure_();
@@ -160,6 +177,8 @@ void ESP32BLETracker::loop() {
 
   */
 
+  // Start scan: reached when scanner_state_ becomes IDLE (via set_scanner_state_()) and
+  // all clients are idle (their state changes increment version when they finish)
   if (this->scanner_state_ == ScannerState::IDLE && !counts.connecting && !counts.disconnecting && !counts.discovered) {
 #ifdef USE_ESP32_BLE_SOFTWARE_COEXISTENCE
     this->update_coex_preference_(false);
@@ -168,8 +187,9 @@ void ESP32BLETracker::loop() {
       this->start_scan_(false);  // first = false
     }
   }
-  // If there is a discovered client and no connecting
-  // clients, then promote the discovered client to ready to connect.
+  // Promote discovered clients: reached when a client's state becomes DISCOVERED (via set_state()),
+  // or when a blocking condition clears (connecting client finishes, scanner reaches RUNNING/IDLE).
+  // All these trigger state_version_ increment, so we'll process and check promotion eligibility.
   // We check both RUNNING and IDLE states because:
   // - RUNNING: gap_scan_event_handler initiates stop_scan_() but promotion can happen immediately
   // - IDLE: Scanner has already stopped (naturally or by gap_scan_event_handler)
@@ -236,6 +256,7 @@ void ESP32BLETracker::start_scan_(bool first) {
   // Start timeout monitoring in loop() instead of using scheduler
   // This prevents false reboots when the loop is blocked
   this->scan_start_time_ = App.get_loop_component_start_time();
+  this->scan_timeout_ms_ = this->scan_duration_ * 2000;
   this->scan_timeout_state_ = ScanTimeoutState::MONITORING;
 
   esp_err_t err = esp_ble_gap_set_scan_params(&this->scan_params_);
@@ -253,6 +274,10 @@ void ESP32BLETracker::start_scan_(bool first) {
 void ESP32BLETracker::register_client(ESPBTClient *client) {
 #ifdef ESPHOME_ESP32_BLE_TRACKER_CLIENT_COUNT
   client->app_id = ++this->app_id_;
+  // Give client a pointer to our state_version_ so it can notify us of state changes.
+  // This enables loop() fast-path optimization - we skip expensive work when no state changed.
+  // Safe because ESP32BLETracker (singleton) outlives all registered clients.
+  client->set_tracker_state_version(&this->state_version_);
   this->clients_.push_back(client);
   this->recalculate_advertisement_parser_types();
 #endif
@@ -382,6 +407,7 @@ void ESP32BLETracker::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_i
 
 void ESP32BLETracker::set_scanner_state_(ScannerState state) {
   this->scanner_state_ = state;
+  this->state_version_++;
   for (auto *listener : this->scanner_state_listeners_) {
     listener->on_scanner_state(state);
   }

esphome/components/esp32_ble_tracker/esp32_ble_tracker.h

@@ -216,6 +216,19 @@ enum class ConnectionType : uint8_t {
   V3_WITHOUT_CACHE
 };
 
+/// Base class for BLE GATT clients that connect to remote devices.
+///
+/// State Change Tracking Design:
+/// -----------------------------
+/// ESP32BLETracker::loop() needs to know when client states change to avoid
+/// expensive polling. Rather than checking all clients every iteration (~7000/min),
+/// we use a version counter owned by ESP32BLETracker that clients increment on
+/// state changes. The tracker compares versions to skip work when nothing changed.
+///
+/// Ownership: ESP32BLETracker owns state_version_. Clients hold a non-owning
+/// pointer (tracker_state_version_) set during register_client(). Clients
+/// increment the counter through this pointer when their state changes.
+/// The pointer may be null if the client is not registered with a tracker.
 class ESPBTClient : public ESPBTDeviceListener {
  public:
   virtual bool gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_t gattc_if,
@@ -225,26 +238,49 @@ class ESPBTClient : public ESPBTDeviceListener {
   virtual void disconnect() = 0;
   bool disconnect_pending() const { return this->want_disconnect_; }
   void cancel_pending_disconnect() { this->want_disconnect_ = false; }
+
+  /// Set the client state with IDLE handling (clears want_disconnect_).
+  /// Notifies the tracker of state change for loop optimization.
   virtual void set_state(ClientState st) {
-    this->state_ = st;
+    this->set_state_internal_(st);
     if (st == ClientState::IDLE) {
       this->want_disconnect_ = false;
     }
   }
-  ClientState state() const { return state_; }
+  ClientState state() const { return this->state_; }
+
+  /// Called by ESP32BLETracker::register_client() to enable state change notifications.
+  /// The pointer must remain valid for the lifetime of the client (guaranteed since
+  /// ESP32BLETracker is a singleton that outlives all clients).
+  void set_tracker_state_version(uint8_t *version) { this->tracker_state_version_ = version; }
 
   // Memory optimized layout
   uint8_t app_id;  // App IDs are small integers assigned sequentially
 
  protected:
-  // Group 1: 1-byte types
-  ClientState state_{ClientState::INIT};
+  /// Set state without IDLE handling - use for direct state transitions.
+  /// Increments the tracker's state version counter to signal that loop()
+  /// should do full processing on the next iteration.
+  void set_state_internal_(ClientState st) {
+    this->state_ = st;
+    // Notify tracker that state changed (tracker_state_version_ is owned by ESP32BLETracker)
+    if (this->tracker_state_version_ != nullptr) {
+      (*this->tracker_state_version_)++;
+    }
+  }
+
   // want_disconnect_ is set to true when a disconnect is requested
   // while the client is connecting. This is used to disconnect the
   // client as soon as we get the connection id (conn_id_) from the
   // ESP_GATTC_OPEN_EVT event.
   bool want_disconnect_{false};
-  // 2 bytes used, 2 bytes padding
+
+ private:
+  ClientState state_{ClientState::INIT};
+  /// Non-owning pointer to ESP32BLETracker::state_version_. When this client's
+  /// state changes, we increment the tracker's counter to signal that loop()
+  /// should perform full processing. Null if client not registered with tracker.
+  uint8_t *tracker_state_version_{nullptr};
 };
 
 class ESP32BLETracker : public Component,
@@ -380,6 +416,16 @@ class ESP32BLETracker : public Component,
   // Group 4: 1-byte types (enums, uint8_t, bool)
   uint8_t app_id_{0};
   uint8_t scan_start_fail_count_{0};
+  /// Version counter for loop() fast-path optimization. Incremented when:
+  /// - Scanner state changes (via set_scanner_state_())
+  /// - Any registered client's state changes (clients hold pointer to this counter)
+  /// Owned by this class; clients receive non-owning pointer via register_client().
+  /// When loop() sees state_version_ == last_processed_version_, it skips expensive
+  /// client state counting and takes the fast path (just timeout check + return).
+  uint8_t state_version_{0};
+  /// Last state_version_ value when loop() did full processing. Compared against
+  /// state_version_ to detect if any state changed since last iteration.
+  uint8_t last_processed_version_{0};
   ScannerState scanner_state_{ScannerState::IDLE};
   bool scan_continuous_;
   bool scan_active_;
@@ -396,6 +442,8 @@ class ESP32BLETracker : public Component,
     EXCEEDED_WAIT,  // Timeout exceeded, waiting one loop before reboot
   };
   uint32_t scan_start_time_{0};
+  /// Precomputed timeout value: scan_duration_ * 2000
+  uint32_t scan_timeout_ms_{0};
   ScanTimeoutState scan_timeout_state_{ScanTimeoutState::INACTIVE};
 };
 

esphome/components/esp8266/preferences.cpp

@@ -12,7 +12,6 @@ extern "C" {
 #include "preferences.h"
 
 #include <cstring>
-#include <memory>
 
 namespace esphome::esp8266 {
 
@@ -143,16 +142,8 @@ class ESP8266PreferenceBackend : public ESPPreferenceBackend {
       return false;
 
     const size_t buffer_size = static_cast<size_t>(this->length_words) + 1;
-    uint32_t stack_buffer[PREF_BUFFER_WORDS];
-    std::unique_ptr<uint32_t[]> heap_buffer;
-    uint32_t *buffer;
-
-    if (buffer_size <= PREF_BUFFER_WORDS) {
-      buffer = stack_buffer;
-    } else {
-      heap_buffer = make_unique<uint32_t[]>(buffer_size);
-      buffer = heap_buffer.get();
-    }
+    SmallBufferWithHeapFallback<PREF_BUFFER_WORDS, uint32_t> buffer_alloc(buffer_size);
+    uint32_t *buffer = buffer_alloc.get();
     memset(buffer, 0, buffer_size * sizeof(uint32_t));
 
     memcpy(buffer, data, len);
@@ -167,16 +158,8 @@ class ESP8266PreferenceBackend : public ESPPreferenceBackend {
       return false;
 
     const size_t buffer_size = static_cast<size_t>(this->length_words) + 1;
-    uint32_t stack_buffer[PREF_BUFFER_WORDS];
-    std::unique_ptr<uint32_t[]> heap_buffer;
-    uint32_t *buffer;
-
-    if (buffer_size <= PREF_BUFFER_WORDS) {
-      buffer = stack_buffer;
-    } else {
-      heap_buffer = make_unique<uint32_t[]>(buffer_size);
-      buffer = heap_buffer.get();
-    }
+    SmallBufferWithHeapFallback<PREF_BUFFER_WORDS, uint32_t> buffer_alloc(buffer_size);
+    uint32_t *buffer = buffer_alloc.get();
 
     bool ret = this->in_flash ? load_from_flash(this->offset, buffer, buffer_size)
                               : load_from_rtc(this->offset, buffer, buffer_size);

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_pmp/ezo_pmp.cpp

@@ -318,90 +318,93 @@ 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), "%s", this->arbitrary_command_);
       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/globals/__init__.py

@@ -9,55 +9,29 @@ from esphome.const import (
     CONF_VALUE,
 )
 from esphome.core import CoroPriority, coroutine_with_priority
-from esphome.types import ConfigType
 
 CODEOWNERS = ["@esphome/core"]
 globals_ns = cg.esphome_ns.namespace("globals")
 GlobalsComponent = globals_ns.class_("GlobalsComponent", cg.Component)
-RestoringGlobalsComponent = globals_ns.class_(
-    "RestoringGlobalsComponent", cg.PollingComponent
-)
+RestoringGlobalsComponent = globals_ns.class_("RestoringGlobalsComponent", cg.Component)
 RestoringGlobalStringComponent = globals_ns.class_(
-    "RestoringGlobalStringComponent", cg.PollingComponent
+    "RestoringGlobalStringComponent", cg.Component
 )
 GlobalVarSetAction = globals_ns.class_("GlobalVarSetAction", automation.Action)
 
 CONF_MAX_RESTORE_DATA_LENGTH = "max_restore_data_length"
 
-# Base schema fields shared by both variants
-_BASE_SCHEMA = {
-    cv.Required(CONF_ID): cv.declare_id(GlobalsComponent),
-    cv.Required(CONF_TYPE): cv.string_strict,
-    cv.Optional(CONF_INITIAL_VALUE): cv.string_strict,
-    cv.Optional(CONF_MAX_RESTORE_DATA_LENGTH): cv.int_range(0, 254),
-}
-
-# Non-restoring globals: regular Component (no polling needed)
-_NON_RESTORING_SCHEMA = cv.Schema(
-    {
-        **_BASE_SCHEMA,
-        cv.Optional(CONF_RESTORE_VALUE, default=False): cv.boolean,
-    }
-).extend(cv.COMPONENT_SCHEMA)
-
-# Restoring globals: PollingComponent with configurable update_interval
-_RESTORING_SCHEMA = cv.Schema(
-    {
-        **_BASE_SCHEMA,
-        cv.Optional(CONF_RESTORE_VALUE, default=True): cv.boolean,
-    }
-).extend(cv.polling_component_schema("1s"))
-
-
-def _globals_schema(config: ConfigType) -> ConfigType:
-    """Select schema based on restore_value setting."""
-    if config.get(CONF_RESTORE_VALUE, False):
-        return _RESTORING_SCHEMA(config)
-    return _NON_RESTORING_SCHEMA(config)
-
 
 MULTI_CONF = True
-CONFIG_SCHEMA = _globals_schema
+CONFIG_SCHEMA = cv.Schema(
+    {
+        cv.Required(CONF_ID): cv.declare_id(GlobalsComponent),
+        cv.Required(CONF_TYPE): cv.string_strict,
+        cv.Optional(CONF_INITIAL_VALUE): cv.string_strict,
+        cv.Optional(CONF_RESTORE_VALUE, default=False): cv.boolean,
+        cv.Optional(CONF_MAX_RESTORE_DATA_LENGTH): cv.int_range(0, 254),
+    }
+).extend(cv.COMPONENT_SCHEMA)
 
 
 # Run with low priority so that namespaces are registered first

esphome/components/globals/globals_component.h

@@ -5,7 +5,8 @@
 #include "esphome/core/helpers.h"
 #include <cstring>
 
-namespace esphome::globals {
+namespace esphome {
+namespace globals {
 
 template<typename T> class GlobalsComponent : public Component {
  public:
@@ -23,14 +24,13 @@ template<typename T> class GlobalsComponent : public Component {
   T value_{};
 };
 
-template<typename T> class RestoringGlobalsComponent : public PollingComponent {
+template<typename T> class RestoringGlobalsComponent : public Component {
  public:
   using value_type = T;
-  explicit RestoringGlobalsComponent() : PollingComponent(1000) {}
-  explicit RestoringGlobalsComponent(T initial_value) : PollingComponent(1000), value_(initial_value) {}
+  explicit RestoringGlobalsComponent() = default;
+  explicit RestoringGlobalsComponent(T initial_value) : value_(initial_value) {}
   explicit RestoringGlobalsComponent(
-      std::array<typename std::remove_extent<T>::type, std::extent<T>::value> initial_value)
-      : PollingComponent(1000) {
+      std::array<typename std::remove_extent<T>::type, std::extent<T>::value> initial_value) {
     memcpy(this->value_, initial_value.data(), sizeof(T));
   }
 
@@ -44,7 +44,7 @@ template<typename T> class RestoringGlobalsComponent : public PollingComponent {
 
   float get_setup_priority() const override { return setup_priority::HARDWARE; }
 
-  void update() override { store_value_(); }
+  void loop() override { store_value_(); }
 
   void on_shutdown() override { store_value_(); }
 
@@ -66,14 +66,13 @@ template<typename T> class RestoringGlobalsComponent : public PollingComponent {
 };
 
 // Use with string or subclasses of strings
-template<typename T, uint8_t SZ> class RestoringGlobalStringComponent : public PollingComponent {
+template<typename T, uint8_t SZ> class RestoringGlobalStringComponent : public Component {
  public:
   using value_type = T;
-  explicit RestoringGlobalStringComponent() : PollingComponent(1000) {}
-  explicit RestoringGlobalStringComponent(T initial_value) : PollingComponent(1000) { this->value_ = initial_value; }
+  explicit RestoringGlobalStringComponent() = default;
+  explicit RestoringGlobalStringComponent(T initial_value) { this->value_ = initial_value; }
   explicit RestoringGlobalStringComponent(
-      std::array<typename std::remove_extent<T>::type, std::extent<T>::value> initial_value)
-      : PollingComponent(1000) {
+      std::array<typename std::remove_extent<T>::type, std::extent<T>::value> initial_value) {
     memcpy(this->value_, initial_value.data(), sizeof(T));
   }
 
@@ -91,7 +90,7 @@ template<typename T, uint8_t SZ> class RestoringGlobalStringComponent : public P
 
   float get_setup_priority() const override { return setup_priority::HARDWARE; }
 
-  void update() override { store_value_(); }
+  void loop() override { store_value_(); }
 
   void on_shutdown() override { store_value_(); }
 
@@ -145,4 +144,5 @@ template<typename T> T &id(GlobalsComponent<T> *value) { return value->value();
 template<typename T> T &id(RestoringGlobalsComponent<T> *value) { return value->value(); }
 template<typename T, uint8_t SZ> T &id(RestoringGlobalStringComponent<T, SZ> *value) { return value->value(); }
 
-}  // namespace esphome::globals
+}  // namespace globals
+}  // namespace esphome

esphome/components/hc8/sensor.py

@@ -6,6 +6,7 @@ from esphome.const import (
     CONF_BASELINE,
     CONF_CO2,
     CONF_ID,
+    CONF_WARMUP_TIME,
     DEVICE_CLASS_CARBON_DIOXIDE,
     ICON_MOLECULE_CO2,
     STATE_CLASS_MEASUREMENT,
@@ -14,8 +15,6 @@ from esphome.const import (
 
 DEPENDENCIES = ["uart"]
 
-CONF_WARMUP_TIME = "warmup_time"
-
 hc8_ns = cg.esphome_ns.namespace("hc8")
 HC8Component = hc8_ns.class_("HC8Component", cg.PollingComponent, uart.UARTDevice)
 HC8CalibrateAction = hc8_ns.class_("HC8CalibrateAction", automation.Action)

esphome/components/heatpumpir/climate.py

@@ -107,7 +107,7 @@ CONFIG_SCHEMA = cv.All(
             cv.Required(CONF_MAX_TEMPERATURE): cv.temperature,
         }
     ),
-    cv.only_with_arduino,
+    cv.Any(cv.only_with_arduino, cv.only_on_esp32),
 )
 
 
@@ -126,6 +126,6 @@ async def to_code(config):
     cg.add(var.set_max_temperature(config[CONF_MAX_TEMPERATURE]))
     cg.add(var.set_min_temperature(config[CONF_MIN_TEMPERATURE]))
 
-    cg.add_library("tonia/HeatpumpIR", "1.0.37")
+    cg.add_library("tonia/HeatpumpIR", "1.0.40")
     if CORE.is_libretiny or CORE.is_esp32:
         CORE.add_platformio_option("lib_ignore", ["IRremoteESP8266"])

esphome/components/heatpumpir/heatpumpir.cpp

@@ -1,6 +1,6 @@
 #include "heatpumpir.h"
 
-#ifdef USE_ARDUINO
+#if defined(USE_ARDUINO) || defined(USE_ESP32)
 
 #include <map>
 #include "ir_sender_esphome.h"

esphome/components/heatpumpir/heatpumpir.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#ifdef USE_ARDUINO
+#if defined(USE_ARDUINO) || defined(USE_ESP32)
 
 #include "esphome/components/climate_ir/climate_ir.h"
 

esphome/components/heatpumpir/ir_sender_esphome.cpp

@@ -1,6 +1,6 @@
 #include "ir_sender_esphome.h"
 
-#ifdef USE_ARDUINO
+#if defined(USE_ARDUINO) || defined(USE_ESP32)
 
 namespace esphome {
 namespace heatpumpir {

esphome/components/heatpumpir/ir_sender_esphome.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#ifdef USE_ARDUINO
+#if defined(USE_ARDUINO) || defined(USE_ESP32)
 
 #include "esphome/components/remote_base/remote_base.h"
 #include <IRSender.h>  // arduino-heatpump library

esphome/components/http_request/__init__.py

@@ -157,6 +157,7 @@ async def to_code(config):
     if CORE.is_esp32:
         cg.add(var.set_buffer_size_rx(config[CONF_BUFFER_SIZE_RX]))
         cg.add(var.set_buffer_size_tx(config[CONF_BUFFER_SIZE_TX]))
+        cg.add(var.set_verify_ssl(config[CONF_VERIFY_SSL]))
 
         if config.get(CONF_VERIFY_SSL):
             esp32.add_idf_sdkconfig_option("CONFIG_MBEDTLS_CERTIFICATE_BUNDLE", True)

esphome/components/http_request/http_request_idf.cpp

@@ -89,7 +89,7 @@ std::shared_ptr<HttpContainer> HttpRequestIDF::perform(const std::string &url, c
   config.max_redirection_count = this->redirect_limit_;
   config.auth_type = HTTP_AUTH_TYPE_BASIC;
 #if CONFIG_MBEDTLS_CERTIFICATE_BUNDLE
-  if (secure) {
+  if (secure && this->verify_ssl_) {
     config.crt_bundle_attach = esp_crt_bundle_attach;
   }
 #endif

esphome/components/http_request/http_request_idf.h

@@ -34,6 +34,7 @@ class HttpRequestIDF : public HttpRequestComponent {
 
   void set_buffer_size_rx(uint16_t buffer_size_rx) { this->buffer_size_rx_ = buffer_size_rx; }
   void set_buffer_size_tx(uint16_t buffer_size_tx) { this->buffer_size_tx_ = buffer_size_tx; }
+  void set_verify_ssl(bool verify_ssl) { this->verify_ssl_ = verify_ssl; }
 
  protected:
   std::shared_ptr<HttpContainer> perform(const std::string &url, const std::string &method, const std::string &body,
@@ -42,6 +43,7 @@ class HttpRequestIDF : public HttpRequestComponent {
   // if zero ESP-IDF will use DEFAULT_HTTP_BUF_SIZE
   uint16_t buffer_size_rx_{};
   uint16_t buffer_size_tx_{};
+  bool verify_ssl_{true};
 
   /// @brief Monitors the http client events to gather response headers
   static esp_err_t http_event_handler(esp_http_client_event_t *evt);

esphome/components/ili9xxx/display.py

@@ -223,7 +223,7 @@ async def to_code(config):
     var = cg.Pvariable(config[CONF_ID], rhs)
 
     await display.register_display(var, config)
-    await spi.register_spi_device(var, config)
+    await spi.register_spi_device(var, config, write_only=True)
     dc = await cg.gpio_pin_expression(config[CONF_DC_PIN])
     cg.add(var.set_dc_pin(dc))
     if init_sequences := config.get(CONF_INIT_SEQUENCE):

esphome/components/json/__init__.py

@@ -1,6 +1,6 @@
 import esphome.codegen as cg
 import esphome.config_validation as cv
-from esphome.core import CoroPriority, coroutine_with_priority
+from esphome.core import CORE, CoroPriority, coroutine_with_priority
 
 CODEOWNERS = ["@esphome/core"]
 json_ns = cg.esphome_ns.namespace("json")
@@ -12,6 +12,11 @@ CONFIG_SCHEMA = cv.All(
 
 @coroutine_with_priority(CoroPriority.BUS)
 async def to_code(config):
-    cg.add_library("bblanchon/ArduinoJson", "7.4.2")
+    if CORE.is_esp32:
+        from esphome.components.esp32 import add_idf_component
+
+        add_idf_component(name="bblanchon/arduinojson", ref="7.4.2")
+    else:
+        cg.add_library("bblanchon/ArduinoJson", "7.4.2")
     cg.add_define("USE_JSON")
     cg.add_global(json_ns.using)

esphome/components/libretiny/__init__.py

@@ -382,4 +382,11 @@ async def component_to_code(config):
             "custom_options.sys_config#h", _BK7231N_SYS_CONFIG_OPTIONS
         )
 
+    # Disable LWIP statistics to save RAM - not needed in production
+    # Must explicitly disable all sub-stats to avoid redefinition warnings
+    cg.add_platformio_option(
+        "custom_options.lwip",
+        ["LWIP_STATS=0", "MEM_STATS=0", "MEMP_STATS=0"],
+    )
+
     await cg.register_component(var, config)

esphome/components/libretiny/preferences.cpp

@@ -166,8 +166,8 @@ class LibreTinyPreferences : public ESPPreferences {
       return true;
     }
 
-    // Allocate buffer on heap to avoid stack allocation for large data
-    auto stored_data = std::make_unique<uint8_t[]>(kv.value_len);
+    // Most preferences are small, use stack buffer with heap fallback for large ones
+    SmallBufferWithHeapFallback<256> stored_data(kv.value_len);
     fdb_blob_make(&this->blob, stored_data.get(), kv.value_len);
     size_t actual_len = fdb_kv_get_blob(db, key_str, &this->blob);
     if (actual_len != kv.value_len) {

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/lock/lock.cpp

@@ -28,16 +28,14 @@ const LogString *lock_state_to_string(LockState state) {
 Lock::Lock() : state(LOCK_STATE_NONE) {}
 LockCall Lock::make_call() { return LockCall(this); }
 
-void Lock::lock() {
+void Lock::set_state_(LockState state) {
   auto call = this->make_call();
-  call.set_state(LOCK_STATE_LOCKED);
-  this->control(call);
-}
-void Lock::unlock() {
-  auto call = this->make_call();
-  call.set_state(LOCK_STATE_UNLOCKED);
+  call.set_state(state);
   this->control(call);
 }
+
+void Lock::lock() { this->set_state_(LOCK_STATE_LOCKED); }
+void Lock::unlock() { this->set_state_(LOCK_STATE_UNLOCKED); }
 void Lock::open() {
   if (traits.get_supports_open()) {
     ESP_LOGD(TAG, "'%s' Opening.", this->get_name().c_str());

esphome/components/lock/lock.h

@@ -156,6 +156,9 @@ class Lock : public EntityBase {
  protected:
   friend LockCall;
 
+  /// Helper for lock/unlock convenience methods
+  void set_state_(LockState state);
+
   /** Perform the open latch action with hardware. This method is optional to implement
    * when creating a new lock.
    *

esphome/components/logger/logger.cpp

@@ -1,8 +1,5 @@
 #include "logger.h"
 #include <cinttypes>
-#ifdef USE_ESPHOME_TASK_LOG_BUFFER
-#include <memory>  // For unique_ptr
-#endif
 
 #include "esphome/core/application.h"
 #include "esphome/core/hal.h"
@@ -199,7 +196,8 @@ inline uint8_t Logger::level_for(const char *tag) {
 
 Logger::Logger(uint32_t baud_rate, size_t tx_buffer_size) : baud_rate_(baud_rate), tx_buffer_size_(tx_buffer_size) {
   // add 1 to buffer size for null terminator
-  this->tx_buffer_ = new char[this->tx_buffer_size_ + 1];  // NOLINT
+  // NOLINTNEXTLINE(cppcoreguidelines-owning-memory) - allocated once, never freed
+  this->tx_buffer_ = new char[this->tx_buffer_size_ + 1];
 #if defined(USE_ESP32) || defined(USE_LIBRETINY)
   this->main_task_ = xTaskGetCurrentTaskHandle();
 #elif defined(USE_ZEPHYR)
@@ -212,11 +210,14 @@ Logger::Logger(uint32_t baud_rate, size_t tx_buffer_size) : baud_rate_(baud_rate
 void Logger::init_log_buffer(size_t total_buffer_size) {
 #ifdef USE_HOST
   // Host uses slot count instead of byte size
-  this->log_buffer_ = esphome::make_unique<logger::TaskLogBufferHost>(total_buffer_size);
+  // NOLINTNEXTLINE(cppcoreguidelines-owning-memory) - allocated once, never freed
+  this->log_buffer_ = new logger::TaskLogBufferHost(total_buffer_size);
 #elif defined(USE_ESP32)
-  this->log_buffer_ = esphome::make_unique<logger::TaskLogBuffer>(total_buffer_size);
+  // NOLINTNEXTLINE(cppcoreguidelines-owning-memory) - allocated once, never freed
+  this->log_buffer_ = new logger::TaskLogBuffer(total_buffer_size);
 #elif defined(USE_LIBRETINY)
-  this->log_buffer_ = esphome::make_unique<logger::TaskLogBufferLibreTiny>(total_buffer_size);
+  // NOLINTNEXTLINE(cppcoreguidelines-owning-memory) - allocated once, never freed
+  this->log_buffer_ = new logger::TaskLogBufferLibreTiny(total_buffer_size);
 #endif
 
 #if defined(USE_ESP32) || defined(USE_LIBRETINY)

esphome/components/logger/logger.h

@@ -412,11 +412,11 @@ class Logger : public Component {
 #endif
 #ifdef USE_ESPHOME_TASK_LOG_BUFFER
 #ifdef USE_HOST
-  std::unique_ptr<logger::TaskLogBufferHost> log_buffer_;  // Will be initialized with init_log_buffer
+  logger::TaskLogBufferHost *log_buffer_{nullptr};  // Allocated once, never freed
 #elif defined(USE_ESP32)
-  std::unique_ptr<logger::TaskLogBuffer> log_buffer_;  // Will be initialized with init_log_buffer
+  logger::TaskLogBuffer *log_buffer_{nullptr};  // Allocated once, never freed
 #elif defined(USE_LIBRETINY)
-  std::unique_ptr<logger::TaskLogBufferLibreTiny> log_buffer_;  // Will be initialized with init_log_buffer
+  logger::TaskLogBufferLibreTiny *log_buffer_{nullptr};  // Allocated once, never freed
 #endif
 #endif
 

esphome/components/lvgl/widgets/dropdown.py

@@ -1,3 +1,4 @@
+from esphome import codegen as cg
 import esphome.config_validation as cv
 from esphome.const import CONF_OPTIONS
 
@@ -24,6 +25,34 @@ from .label import CONF_LABEL
 CONF_DROPDOWN = "dropdown"
 CONF_DROPDOWN_LIST = "dropdown_list"
 
+# Example valid dropdown symbol (left arrow) for error messages
+EXAMPLE_DROPDOWN_SYMBOL = "\U00002190"  # ←
+
+
+def dropdown_symbol_validator(value):
+    """
+    Validate that the dropdown symbol is a single Unicode character
+    with a codepoint of 0x100 (256) or greater.
+    This is required because LVGL uses codepoints below 0x100 for internal symbols.
+    """
+    value = cv.string(value)
+    # len(value) counts Unicode code points, not grapheme clusters or bytes
+    if len(value) != 1:
+        raise cv.Invalid(
+            f"Dropdown symbol must be a single character, got '{value}' with length {len(value)}"
+        )
+    codepoint = ord(value)
+    if codepoint < 0x100:
+        # Format the example symbol as a Unicode escape for the error message
+        example_escape = f"\\U{ord(EXAMPLE_DROPDOWN_SYMBOL):08X}"
+        raise cv.Invalid(
+            f"Dropdown symbol must have a Unicode codepoint of 0x100 (256) or greater. "
+            f"'{value}' has codepoint {codepoint} (0x{codepoint:X}). "
+            f"Use a character like '{example_escape}' ({EXAMPLE_DROPDOWN_SYMBOL}) or other Unicode symbols with codepoint >= 0x100."
+        )
+    return value
+
+
 lv_dropdown_t = LvSelect("LvDropdownType", parents=(LvCompound,))
 
 lv_dropdown_list_t = LvType("lv_dropdown_list_t")
@@ -33,7 +62,7 @@ dropdown_list_spec = WidgetType(
 
 DROPDOWN_BASE_SCHEMA = cv.Schema(
     {
-        cv.Optional(CONF_SYMBOL): lv_text,
+        cv.Optional(CONF_SYMBOL): dropdown_symbol_validator,
         cv.Exclusive(CONF_SELECTED_INDEX, CONF_SELECTED_TEXT): lv_int,
         cv.Exclusive(CONF_SELECTED_TEXT, CONF_SELECTED_TEXT): lv_text,
         cv.Optional(CONF_DROPDOWN_LIST): part_schema(dropdown_list_spec.parts),
@@ -70,7 +99,7 @@ class DropdownType(WidgetType):
         if options := config.get(CONF_OPTIONS):
             lv_add(w.var.set_options(options))
         if symbol := config.get(CONF_SYMBOL):
-            lv.dropdown_set_symbol(w.var.obj, await lv_text.process(symbol))
+            lv.dropdown_set_symbol(w.var.obj, cg.safe_exp(symbol))
         if (selected := config.get(CONF_SELECTED_INDEX)) is not None:
             value = await lv_int.process(selected)
             lv_add(w.var.set_selected_index(value, literal("LV_ANIM_OFF")))

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/max7219/display.py

@@ -29,7 +29,7 @@ CONFIG_SCHEMA = (
 
 async def to_code(config):
     var = cg.new_Pvariable(config[CONF_ID])
-    await spi.register_spi_device(var, config)
+    await spi.register_spi_device(var, config, write_only=True)
     await display.register_display(var, config)
 
     cg.add(var.set_num_chips(config[CONF_NUM_CHIPS]))

esphome/components/max7219digit/display.py

@@ -86,7 +86,7 @@ CONFIG_SCHEMA = (
 
 async def to_code(config):
     var = cg.new_Pvariable(config[CONF_ID])
-    await spi.register_spi_device(var, config)
+    await spi.register_spi_device(var, config, write_only=True)
     await display.register_display(var, config)
 
     cg.add(var.set_num_chips(config[CONF_NUM_CHIPS]))

esphome/components/mdns/mdns_esp32.cpp

@@ -24,13 +24,14 @@ static void register_esp32(MDNSComponent *comp, StaticVector<MDNSService, MDNS_S
   mdns_instance_name_set(hostname);
 
   for (const auto &service : services) {
-    auto txt_records = std::make_unique<mdns_txt_item_t[]>(service.txt_records.size());
+    // Stack buffer for up to 16 txt records, heap fallback for more
+    SmallBufferWithHeapFallback<16, mdns_txt_item_t> txt_records(service.txt_records.size());
     for (size_t i = 0; i < service.txt_records.size(); i++) {
       const auto &record = service.txt_records[i];
       // key and value are either compile-time string literals in flash or pointers to dynamic_txt_values_
       // Both remain valid for the lifetime of this function, and ESP-IDF makes internal copies
-      txt_records[i].key = MDNS_STR_ARG(record.key);
-      txt_records[i].value = MDNS_STR_ARG(record.value);
+      txt_records.get()[i].key = MDNS_STR_ARG(record.key);
+      txt_records.get()[i].value = MDNS_STR_ARG(record.value);
     }
     uint16_t port = const_cast<TemplatableValue<uint16_t> &>(service.port).value();
     err = mdns_service_add(nullptr, MDNS_STR_ARG(service.service_type), MDNS_STR_ARG(service.proto), port,

esphome/components/mhz19/sensor.py

@@ -7,6 +7,7 @@ from esphome.const import (
     CONF_CO2,
     CONF_ID,
     CONF_TEMPERATURE,
+    CONF_WARMUP_TIME,
     DEVICE_CLASS_CARBON_DIOXIDE,
     DEVICE_CLASS_TEMPERATURE,
     ICON_MOLECULE_CO2,
@@ -18,7 +19,6 @@ from esphome.const import (
 DEPENDENCIES = ["uart"]
 
 CONF_AUTOMATIC_BASELINE_CALIBRATION = "automatic_baseline_calibration"
-CONF_WARMUP_TIME = "warmup_time"
 CONF_DETECTION_RANGE = "detection_range"
 
 mhz19_ns = cg.esphome_ns.namespace("mhz19")

esphome/components/mipi_rgb/display.py

@@ -260,7 +260,7 @@ async def to_code(config):
         cg.add(var.set_enable_pins(enable))
 
     if CONF_SPI_ID in config:
-        await spi.register_spi_device(var, config)
+        await spi.register_spi_device(var, config, write_only=True)
         sequence, madctl = model.get_sequence(config)
         cg.add(var.set_init_sequence(sequence))
         cg.add(var.set_madctl(madctl))

esphome/components/mipi_spi/display.py

@@ -443,6 +443,4 @@ async def to_code(config):
         )
         cg.add(var.set_writer(lambda_))
     await display.register_display(var, config)
-    await spi.register_spi_device(var, config)
-    # Displays are write-only, set the SPI device to write-only as well
-    cg.add(var.set_write_only(True))
+    await spi.register_spi_device(var, config, write_only=True)

esphome/components/mipi_spi/mipi_spi.h

@@ -224,12 +224,9 @@ class MipiSpi : public display::Display,
                     this->madctl_ & MADCTL_BGR ? "BGR" : "RGB", DISPLAYPIXEL * 8, IS_BIG_ENDIAN ? "Big" : "Little");
     if (this->brightness_.has_value())
       esph_log_config(TAG, "  Brightness: %u", this->brightness_.value());
-    if (this->cs_ != nullptr)
-      esph_log_config(TAG, "  CS Pin: %s", this->cs_->dump_summary().c_str());
-    if (this->reset_pin_ != nullptr)
-      esph_log_config(TAG, "  Reset Pin: %s", this->reset_pin_->dump_summary().c_str());
-    if (this->dc_pin_ != nullptr)
-      esph_log_config(TAG, "  DC Pin: %s", this->dc_pin_->dump_summary().c_str());
+    log_pin(TAG, "  CS Pin: ", this->cs_);
+    log_pin(TAG, "  Reset Pin: ", this->reset_pin_);
+    log_pin(TAG, "  DC Pin: ", this->dc_pin_);
     esph_log_config(TAG,
                     "  SPI Mode: %d\n"
                     "  SPI Data rate: %dMHz\n"

esphome/components/mipi_spi/models/adafruit.py

@@ -26,5 +26,3 @@ ST7789V.extend(
     reset_pin=40,
     invert_colors=True,
 )
-
-models = {}

esphome/components/mipi_spi/models/amoled.py

@@ -105,6 +105,3 @@ CO5300 = DriverChip(
         (WCE, 0x00),
     ),
 )
-
-
-models = {}

esphome/components/mipi_spi/models/cyd.py

@@ -1,10 +1,45 @@
-from .ili import ILI9341
+from .ili import ILI9341, ILI9342, ST7789V
 
 ILI9341.extend(
+    # ESP32-2432S028 CYD board with Micro USB, has ILI9341 controller
     "ESP32-2432S028",
     data_rate="40MHz",
-    cs_pin=15,
-    dc_pin=2,
+    cs_pin={"number": 15, "ignore_strapping_warning": True},
+    dc_pin={"number": 2, "ignore_strapping_warning": True},
 )
 
-models = {}
+ST7789V.extend(
+    # ESP32-2432S028 CYD board with USB C + Micro USB, has ST7789V controller
+    "ESP32-2432S028-7789",
+    data_rate="40MHz",
+    cs_pin={"number": 15, "ignore_strapping_warning": True},
+    dc_pin={"number": 2, "ignore_strapping_warning": True},
+)
+
+# fmt: off
+
+ILI9342.extend(
+    # ESP32-2432S028 CYD board with USB C + Micro USB, has ILI9342 controller
+    "ESP32-2432S028-9342",
+    data_rate="40MHz",
+    cs_pin={"number": 15, "ignore_strapping_warning": True},
+    dc_pin={"number": 2, "ignore_strapping_warning": True},
+    initsequence=(
+        (0xCB, 0x39, 0x2C, 0x00, 0x34, 0x02),  # Power Control A
+        (0xCF, 0x00, 0xC1, 0x30),  # Power Control B
+        (0xE8, 0x85, 0x00, 0x78),  # Driver timing control A
+        (0xEA, 0x00, 0x00),  # Driver timing control B
+        (0xED, 0x64, 0x03, 0x12, 0x81),  # Power on sequence control
+        (0xF7, 0x20),  # Pump ratio control
+        (0xC0, 0x23),  # Power Control 1
+        (0xC1, 0x10),  # Power Control 2
+        (0xC5, 0x3E, 0x28),  # VCOM Control 1
+        (0xC7, 0x86),  # VCOM Control 2
+        (0xB1, 0x00, 0x1B),  # Frame Rate Control
+        (0xB6, 0x0A, 0xA2, 0x27, 0x00),  # Display Function Control
+        (0xF2, 0x00),  # Enable 3G
+        (0x26, 0x01),  # Gamma Set
+        (0xE0, 0x00, 0x0C, 0x11, 0x04, 0x11, 0x08, 0x37, 0x89, 0x4C, 0x06, 0x0C, 0x0A, 0x2E, 0x34, 0x0F),  # Positive Gamma Correction
+        (0xE1, 0x00, 0x0B, 0x11, 0x05, 0x13, 0x09, 0x33, 0x67, 0x48, 0x07, 0x0E, 0x0B, 0x23, 0x33, 0x0F),  # Negative Gamma Correction
+    )
+)

esphome/components/mipi_spi/models/ili.py

@@ -148,6 +148,34 @@ ILI9341 = DriverChip(
         ),
     ),
 )
+
+# fmt: off
+
+ILI9342 = DriverChip(
+    "ILI9342",
+    width=320,
+    height=240,
+    mirror_x=True,
+    initsequence=(
+        (0xCB, 0x39, 0x2C, 0x00, 0x34, 0x02),  # Power Control A
+        (0xCF, 0x00, 0xC1, 0x30),  # Power Control B
+        (0xE8, 0x85, 0x00, 0x78),  # Driver timing control A
+        (0xEA, 0x00, 0x00),  # Driver timing control B
+        (0xED, 0x64, 0x03, 0x12, 0x81),  # Power on sequence control
+        (0xF7, 0x20),  # Pump ratio control
+        (0xC0, 0x23),  # Power Control 1
+        (0xC1, 0x10),  # Power Control 2
+        (0xC5, 0x3E, 0x28),  # VCOM Control 1
+        (0xC7, 0x86),  # VCOM Control 2
+        (0xB1, 0x00, 0x1B),  # Frame Rate Control
+        (0xB6, 0x0A, 0xA2, 0x27, 0x00),  # Display Function Control
+        (0xF2, 0x00),  # Enable 3G
+        (0x26, 0x01),  # Gamma Set
+        (0xE0, 0x0F, 0x1F, 0x1C, 0x0C, 0x0F, 0x08, 0x48, 0x98, 0x37, 0x0A, 0x13, 0x04, 0x11, 0x0D, 0x00),  # Positive Gamma
+        (0xE1, 0x0F, 0x32, 0x2E, 0x0B, 0x0D, 0x05, 0x47, 0x75, 0x37, 0x06, 0x10, 0x03, 0x24, 0x20, 0x00),  # Negative Gamma
+    ),
+)
+
 # M5Stack Core2 uses ILI9341 chip - mirror_x disabled for correct orientation
 ILI9341.extend(
     "M5CORE2",
@@ -758,5 +786,3 @@ ST7796.extend(
     dc_pin=0,
     invert_colors=True,
 )
-
-models = {}

esphome/components/mipi_spi/models/jc.py

@@ -588,5 +588,3 @@ DriverChip(
         (0x29, 0x00),
     ),
 )
-
-models = {}

esphome/components/mipi_spi/models/lanbon.py

@@ -11,5 +11,3 @@ ST7789V.extend(
     dc_pin=21,
     reset_pin=18,
 )
-
-models = {}

esphome/components/mipi_spi/models/lilygo.py

@@ -56,5 +56,3 @@ ST7796.extend(
     backlight_pin=48,
     invert_colors=True,
 )
-
-models = {}

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_alarm_control_panel.cpp

@@ -43,7 +43,7 @@ void MQTTAlarmControlPanelComponent::setup() {
 
 void MQTTAlarmControlPanelComponent::dump_config() {
   ESP_LOGCONFIG(TAG, "MQTT alarm_control_panel '%s':", this->alarm_control_panel_->get_name().c_str());
-  LOG_MQTT_COMPONENT(true, true)
+  LOG_MQTT_COMPONENT(true, true);
   ESP_LOGCONFIG(TAG,
                 "  Supported Features: %" PRIu32 "\n"
                 "  Requires Code to Disarm: %s\n"
@@ -119,7 +119,8 @@ bool MQTTAlarmControlPanelComponent::publish_state() {
     default:
       state_s = "unknown";
   }
-  return this->publish(this->get_state_topic_(), state_s);
+  char topic_buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
+  return this->publish(this->get_state_topic_to_(topic_buf), state_s);
 }
 
 }  // namespace esphome::mqtt

esphome/components/mqtt/mqtt_binary_sensor.cpp

@@ -19,7 +19,7 @@ void MQTTBinarySensorComponent::setup() {
 
 void MQTTBinarySensorComponent::dump_config() {
   ESP_LOGCONFIG(TAG, "MQTT Binary Sensor '%s':", this->binary_sensor_->get_name().c_str());
-  LOG_MQTT_COMPONENT(true, false)
+  LOG_MQTT_COMPONENT(true, false);
 }
 MQTTBinarySensorComponent::MQTTBinarySensorComponent(binary_sensor::BinarySensor *binary_sensor)
     : binary_sensor_(binary_sensor) {
@@ -52,8 +52,9 @@ bool MQTTBinarySensorComponent::publish_state(bool state) {
   if (this->binary_sensor_->is_status_binary_sensor())
     return true;
 
+  char topic_buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
   const char *state_s = state ? "ON" : "OFF";
-  return this->publish(this->get_state_topic_(), state_s);
+  return this->publish(this->get_state_topic_to_(topic_buf), state_s);
 }
 
 }  // namespace esphome::mqtt

esphome/components/mqtt/mqtt_client.cpp

@@ -5,6 +5,7 @@
 #include <utility>
 #include "esphome/components/network/util.h"
 #include "esphome/core/application.h"
+#include "esphome/core/entity_base.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 #include "esphome/core/version.h"
@@ -66,10 +67,13 @@ void MQTTClientComponent::setup() {
         "esphome/discover", [this](const std::string &topic, const std::string &payload) { this->send_device_info_(); },
         2);
 
-    std::string topic = "esphome/ping/";
-    topic.append(App.get_name());
+    // Format topic on stack - subscribe() copies it
+    // "esphome/ping/" (13) + name (ESPHOME_DEVICE_NAME_MAX_LEN) + null (1)
+    constexpr size_t ping_topic_buffer_size = 13 + ESPHOME_DEVICE_NAME_MAX_LEN + 1;
+    char ping_topic[ping_topic_buffer_size];
+    buf_append_printf(ping_topic, sizeof(ping_topic), 0, "esphome/ping/%s", App.get_name().c_str());
     this->subscribe(
-        topic, [this](const std::string &topic, const std::string &payload) { this->send_device_info_(); }, 2);
+        ping_topic, [this](const std::string &topic, const std::string &payload) { this->send_device_info_(); }, 2);
   }
 
   if (this->enable_on_boot_) {
@@ -81,8 +85,11 @@ void MQTTClientComponent::send_device_info_() {
   if (!this->is_connected() or !this->is_discovery_ip_enabled()) {
     return;
   }
-  std::string topic = "esphome/discover/";
-  topic.append(App.get_name());
+  // Format topic on stack to avoid heap allocation
+  // "esphome/discover/" (17) + name (ESPHOME_DEVICE_NAME_MAX_LEN) + null (1)
+  constexpr size_t topic_buffer_size = 17 + ESPHOME_DEVICE_NAME_MAX_LEN + 1;
+  char topic[topic_buffer_size];
+  buf_append_printf(topic, sizeof(topic), 0, "esphome/discover/%s", App.get_name().c_str());
 
   // NOLINTBEGIN(clang-analyzer-cplusplus.NewDeleteLeaks) false positive with ArduinoJson
   this->publish_json(
@@ -91,7 +98,17 @@ 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++;
           }
         }
@@ -396,6 +413,12 @@ void MQTTClientComponent::loop() {
 
         this->last_connected_ = now;
         this->resubscribe_subscriptions_();
+
+        // Process pending resends for all MQTT components centrally
+        // This is more efficient than each component polling in its own loop
+        for (MQTTComponent *component : this->children_) {
+          component->process_resend();
+        }
       }
       break;
   }
@@ -500,39 +523,49 @@ bool MQTTClientComponent::publish(const std::string &topic, const std::string &p
 
 bool MQTTClientComponent::publish(const std::string &topic, const char *payload, size_t payload_length, uint8_t qos,
                                   bool retain) {
-  return publish({.topic = topic, .payload = std::string(payload, payload_length), .qos = qos, .retain = retain});
+  return this->publish(topic.c_str(), payload, payload_length, qos, retain);
 }
 
 bool MQTTClientComponent::publish(const MQTTMessage &message) {
+  return this->publish(message.topic.c_str(), message.payload.c_str(), message.payload.length(), message.qos,
+                       message.retain);
+}
+bool MQTTClientComponent::publish_json(const std::string &topic, const json::json_build_t &f, uint8_t qos,
+                                       bool retain) {
+  return this->publish_json(topic.c_str(), f, qos, retain);
+}
+
+bool MQTTClientComponent::publish(const char *topic, const char *payload, size_t payload_length, uint8_t qos,
+                                  bool retain) {
   if (!this->is_connected()) {
-    // critical components will re-transmit their messages
     return false;
   }
-  bool logging_topic = this->log_message_.topic == message.topic;
-  bool ret = this->mqtt_backend_.publish(message);
+  size_t topic_len = strlen(topic);
+  bool logging_topic = (topic_len == this->log_message_.topic.size()) &&
+                       (memcmp(this->log_message_.topic.c_str(), topic, topic_len) == 0);
+  bool ret = this->mqtt_backend_.publish(topic, payload, payload_length, qos, retain);
   delay(0);
   if (!ret && !logging_topic && this->is_connected()) {
     delay(0);
-    ret = this->mqtt_backend_.publish(message);
+    ret = this->mqtt_backend_.publish(topic, payload, payload_length, qos, retain);
     delay(0);
   }
 
   if (!logging_topic) {
     if (ret) {
-      ESP_LOGV(TAG, "Publish(topic='%s' payload='%s' retain=%d qos=%d)", message.topic.c_str(), message.payload.c_str(),
-               message.retain, message.qos);
+      ESP_LOGV(TAG, "Publish(topic='%s' retain=%d qos=%d)", topic, retain, qos);
+      ESP_LOGVV(TAG, "Publish payload (len=%u): '%.*s'", payload_length, static_cast<int>(payload_length), payload);
     } else {
-      ESP_LOGV(TAG, "Publish failed for topic='%s' (len=%u). Will retry", message.topic.c_str(),
-               message.payload.length());
+      ESP_LOGV(TAG, "Publish failed for topic='%s' (len=%u). Will retry", topic, payload_length);
       this->status_momentary_warning("publish", 1000);
     }
   }
   return ret != 0;
 }
-bool MQTTClientComponent::publish_json(const std::string &topic, const json::json_build_t &f, uint8_t qos,
-                                       bool retain) {
+
+bool MQTTClientComponent::publish_json(const char *topic, const json::json_build_t &f, uint8_t qos, bool retain) {
   std::string message = json::build_json(f);
-  return this->publish(topic, message, qos, retain);
+  return this->publish(topic, message.c_str(), message.length(), qos, retain);
 }
 
 void MQTTClientComponent::enable() {
@@ -610,18 +643,10 @@ static bool topic_match(const char *message, const char *subscription) {
 }
 
 void MQTTClientComponent::on_message(const std::string &topic, const std::string &payload) {
-#ifdef USE_ESP8266
-  // on ESP8266, this is called in lwIP/AsyncTCP task; some components do not like running
-  // from a different task.
-  this->defer([this, topic, payload]() {
-#endif
-    for (auto &subscription : this->subscriptions_) {
-      if (topic_match(topic.c_str(), subscription.topic.c_str()))
-        subscription.callback(topic, payload);
-    }
-#ifdef USE_ESP8266
-  });
-#endif
+  for (auto &subscription : this->subscriptions_) {
+    if (topic_match(topic.c_str(), subscription.topic.c_str()))
+      subscription.callback(topic, payload);
+  }
 }
 
 // Setters

esphome/components/mqtt/mqtt_client.h

@@ -229,6 +229,9 @@ class MQTTClientComponent : public Component
   bool publish(const std::string &topic, const char *payload, size_t payload_length, uint8_t qos = 0,
                bool retain = false);
 
+  /// Publish directly without creating MQTTMessage (avoids heap allocation for topic)
+  bool publish(const char *topic, const char *payload, size_t payload_length, uint8_t qos = 0, bool retain = false);
+
   /** Construct and send a JSON MQTT message.
    *
    * @param topic The topic.
@@ -237,6 +240,9 @@ class MQTTClientComponent : public Component
    */
   bool publish_json(const std::string &topic, const json::json_build_t &f, uint8_t qos = 0, bool retain = false);
 
+  /// Publish JSON directly without heap allocation for topic
+  bool publish_json(const char *topic, const json::json_build_t &f, uint8_t qos = 0, bool retain = false);
+
   /// Setup the MQTT client, registering a bunch of callbacks and attempting to connect.
   void setup() override;
   void dump_config() override;

esphome/components/mqtt/mqtt_component.cpp

@@ -27,20 +27,23 @@ inline char *append_char(char *p, char c) {
 // Max lengths for stack-based topic building.
 // These limits are enforced at Python config validation time in mqtt/__init__.py
 // using cv.Length() validators for topic_prefix and discovery_prefix.
-// MQTT_COMPONENT_TYPE_MAX_LEN and MQTT_SUFFIX_MAX_LEN are defined in mqtt_component.h.
+// MQTT_COMPONENT_TYPE_MAX_LEN, MQTT_SUFFIX_MAX_LEN, and MQTT_DEFAULT_TOPIC_MAX_LEN are in mqtt_component.h.
 // ESPHOME_DEVICE_NAME_MAX_LEN and OBJECT_ID_MAX_LEN are defined in entity_base.h.
 // This ensures the stack buffers below are always large enough.
-static constexpr size_t TOPIC_PREFIX_MAX_LEN = 64;      // Validated in Python: cv.Length(max=64)
 static constexpr size_t DISCOVERY_PREFIX_MAX_LEN = 64;  // Validated in Python: cv.Length(max=64)
-
-// Stack buffer sizes - safe because all inputs are length-validated at config time
-// Format: prefix + "/" + type + "/" + object_id + "/" + suffix + null
-static constexpr size_t DEFAULT_TOPIC_MAX_LEN =
-    TOPIC_PREFIX_MAX_LEN + 1 + MQTT_COMPONENT_TYPE_MAX_LEN + 1 + OBJECT_ID_MAX_LEN + 1 + MQTT_SUFFIX_MAX_LEN + 1;
 // Format: prefix + "/" + type + "/" + name + "/" + object_id + "/config" + null
 static constexpr size_t DISCOVERY_TOPIC_MAX_LEN = DISCOVERY_PREFIX_MAX_LEN + 1 + MQTT_COMPONENT_TYPE_MAX_LEN + 1 +
                                                   ESPHOME_DEVICE_NAME_MAX_LEN + 1 + OBJECT_ID_MAX_LEN + 7 + 1;
 
+// Function implementation of LOG_MQTT_COMPONENT macro to reduce code size
+void log_mqtt_component(const char *tag, MQTTComponent *obj, bool state_topic, bool command_topic) {
+  char buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
+  if (state_topic)
+    ESP_LOGCONFIG(tag, "  State Topic: '%s'", obj->get_state_topic_to_(buf).c_str());
+  if (command_topic)
+    ESP_LOGCONFIG(tag, "  Command Topic: '%s'", obj->get_command_topic_to_(buf).c_str());
+}
+
 void MQTTComponent::set_qos(uint8_t qos) { this->qos_ = qos; }
 
 void MQTTComponent::set_subscribe_qos(uint8_t qos) { this->subscribe_qos_ = qos; }
@@ -69,19 +72,18 @@ std::string MQTTComponent::get_discovery_topic_(const MQTTDiscoveryInfo &discove
   return std::string(buf, p - buf);
 }
 
-std::string MQTTComponent::get_default_topic_for_(const std::string &suffix) const {
+StringRef MQTTComponent::get_default_topic_for_to_(std::span<char, MQTT_DEFAULT_TOPIC_MAX_LEN> buf, const char *suffix,
+                                                   size_t suffix_len) const {
   const std::string &topic_prefix = global_mqtt_client->get_topic_prefix();
   if (topic_prefix.empty()) {
-    // If the topic_prefix is null, the default topic should be null
-    return "";
+    return StringRef();  // Empty topic_prefix means no default topic
   }
 
   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);
 
-  char buf[DEFAULT_TOPIC_MAX_LEN];
-  char *p = buf;
+  char *p = buf.data();
 
   p = append_str(p, topic_prefix.data(), topic_prefix.size());
   p = append_char(p, '/');
@@ -89,35 +91,70 @@ std::string MQTTComponent::get_default_topic_for_(const std::string &suffix) con
   p = append_char(p, '/');
   p = append_str(p, object_id.c_str(), object_id.size());
   p = append_char(p, '/');
-  p = append_str(p, suffix.data(), suffix.size());
+  p = append_str(p, suffix, suffix_len);
+  *p = '\0';
 
-  return std::string(buf, p - buf);
+  return StringRef(buf.data(), p - buf.data());
+}
+
+std::string MQTTComponent::get_default_topic_for_(const std::string &suffix) const {
+  char buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
+  StringRef ref = this->get_default_topic_for_to_(buf, suffix.data(), suffix.size());
+  return std::string(ref.c_str(), ref.size());
+}
+
+StringRef MQTTComponent::get_state_topic_to_(std::span<char, MQTT_DEFAULT_TOPIC_MAX_LEN> buf) const {
+  if (this->custom_state_topic_.has_value()) {
+    // Returns ref to existing data for static/value, uses buf only for lambda case
+    return this->custom_state_topic_.ref_or_copy_to(buf.data(), buf.size());
+  }
+  return this->get_default_topic_for_to_(buf, "state", 5);
+}
+
+StringRef MQTTComponent::get_command_topic_to_(std::span<char, MQTT_DEFAULT_TOPIC_MAX_LEN> buf) const {
+  if (this->custom_command_topic_.has_value()) {
+    // Returns ref to existing data for static/value, uses buf only for lambda case
+    return this->custom_command_topic_.ref_or_copy_to(buf.data(), buf.size());
+  }
+  return this->get_default_topic_for_to_(buf, "command", 7);
 }
 
 std::string MQTTComponent::get_state_topic_() const {
-  if (this->custom_state_topic_.has_value())
-    return this->custom_state_topic_.value();
-  return this->get_default_topic_for_("state");
+  char buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
+  StringRef ref = this->get_state_topic_to_(buf);
+  return std::string(ref.c_str(), ref.size());
 }
 
 std::string MQTTComponent::get_command_topic_() const {
-  if (this->custom_command_topic_.has_value())
-    return this->custom_command_topic_.value();
-  return this->get_default_topic_for_("command");
+  char buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
+  StringRef ref = this->get_command_topic_to_(buf);
+  return std::string(ref.c_str(), ref.size());
 }
 
 bool MQTTComponent::publish(const std::string &topic, const std::string &payload) {
-  return this->publish(topic, payload.data(), payload.size());
+  return this->publish(topic.c_str(), payload.data(), payload.size());
 }
 
 bool MQTTComponent::publish(const std::string &topic, const char *payload, size_t payload_length) {
-  if (topic.empty())
+  return this->publish(topic.c_str(), payload, payload_length);
+}
+
+bool MQTTComponent::publish(const char *topic, const char *payload, size_t payload_length) {
+  if (topic[0] == '\0')
     return false;
   return global_mqtt_client->publish(topic, payload, payload_length, this->qos_, this->retain_);
 }
 
+bool MQTTComponent::publish(const char *topic, const char *payload) {
+  return this->publish(topic, payload, strlen(payload));
+}
+
 bool MQTTComponent::publish_json(const std::string &topic, const json::json_build_t &f) {
-  if (topic.empty())
+  return this->publish_json(topic.c_str(), f);
+}
+
+bool MQTTComponent::publish_json(const char *topic, const json::json_build_t &f) {
+  if (topic[0] == '\0')
     return false;
   return global_mqtt_client->publish_json(topic, f, this->qos_, this->retain_);
 }
@@ -168,10 +205,14 @@ bool MQTTComponent::send_discovery_() {
             break;
         }
 
-        if (config.state_topic)
-          root[MQTT_STATE_TOPIC] = this->get_state_topic_();
-        if (config.command_topic)
-          root[MQTT_COMMAND_TOPIC] = this->get_command_topic_();
+        if (config.state_topic) {
+          char state_topic_buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
+          root[MQTT_STATE_TOPIC] = this->get_state_topic_to_(state_topic_buf);
+        }
+        if (config.command_topic) {
+          char command_topic_buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
+          root[MQTT_COMMAND_TOPIC] = this->get_command_topic_to_(command_topic_buf);
+        }
         if (this->command_retain_)
           root[MQTT_COMMAND_RETAIN] = true;
 
@@ -190,27 +231,37 @@ 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];
@@ -221,18 +272,29 @@ 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";
@@ -246,7 +308,7 @@ 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;
         }
 
@@ -288,7 +350,9 @@ void MQTTComponent::set_availability(std::string topic, std::string payload_avai
 }
 void MQTTComponent::disable_availability() { this->set_availability("", "", ""); }
 void MQTTComponent::call_setup() {
-  if (this->is_internal())
+  // Cache is_internal result once during setup - topics don't change after this
+  this->is_internal_ = this->compute_is_internal_();
+  if (this->is_internal_)
     return;
 
   this->setup();
@@ -308,16 +372,12 @@ void MQTTComponent::call_setup() {
   }
 }
 
-void MQTTComponent::call_loop() {
-  if (this->is_internal())
+void MQTTComponent::process_resend() {
+  // Called by MQTTClientComponent when connected to process pending resends
+  // Note: is_internal() check not needed - internal components are never registered
+  if (!this->resend_state_)
     return;
 
-  this->loop();
-
-  if (!this->resend_state_ || !this->is_connected_()) {
-    return;
-  }
-
   this->resend_state_ = false;
   if (this->is_discovery_enabled()) {
     if (!this->send_discovery_()) {
@@ -344,26 +404,28 @@ StringRef MQTTComponent::get_default_object_id_to_(std::span<char, OBJECT_ID_MAX
 }
 StringRef MQTTComponent::get_icon_ref_() const { return this->get_entity()->get_icon_ref(); }
 bool MQTTComponent::is_disabled_by_default_() const { return this->get_entity()->is_disabled_by_default(); }
-bool MQTTComponent::is_internal() {
+bool MQTTComponent::compute_is_internal_() {
   if (this->custom_state_topic_.has_value()) {
-    // If the custom state_topic is null, return true as it is internal and should not publish
+    // If the custom state_topic is empty, return true as it is internal and should not publish
     // else, return false, as it is explicitly set to a topic, so it is not internal and should publish
-    return this->get_state_topic_().empty();
+    // Using is_empty() avoids heap allocation for non-lambda cases
+    return this->custom_state_topic_.is_empty();
   }
 
   if (this->custom_command_topic_.has_value()) {
-    // If the custom command_topic is null, return true as it is internal and should not publish
+    // If the custom command_topic is empty, return true as it is internal and should not publish
     // else, return false, as it is explicitly set to a topic, so it is not internal and should publish
-    return this->get_command_topic_().empty();
+    // Using is_empty() avoids heap allocation for non-lambda cases
+    return this->custom_command_topic_.is_empty();
   }
 
-  // No custom topics have been set
-  if (this->get_default_topic_for_("").empty()) {
-    // If the default topic prefix is null, then the component, by default, is internal and should not publish
+  // No custom topics have been set - check topic_prefix directly to avoid allocation
+  if (global_mqtt_client->get_topic_prefix().empty()) {
+    // If the default topic prefix is empty, then the component, by default, is internal and should not publish
     return true;
   }
 
-  // Use ESPHome's component internal state if topic_prefix is not null with no custom state_topic or command_topic
+  // Use ESPHome's component internal state if topic_prefix is not empty with no custom state_topic or command_topic
   return this->get_entity()->is_internal();
 }
 

esphome/components/mqtt/mqtt_component.h

@@ -20,17 +20,22 @@ struct SendDiscoveryConfig {
   bool command_topic{true};  ///< If the command topic should be included. Default to true.
 };
 
-// Max lengths for stack-based topic building (must match mqtt_component.cpp)
+// Max lengths for stack-based topic building.
+// These limits are enforced at Python config validation time in mqtt/__init__.py
+// using cv.Length() validators for topic_prefix and discovery_prefix.
+// This ensures the stack buffers are always large enough.
 static constexpr size_t MQTT_COMPONENT_TYPE_MAX_LEN = 20;
 static constexpr size_t MQTT_SUFFIX_MAX_LEN = 32;
+static constexpr size_t MQTT_TOPIC_PREFIX_MAX_LEN = 64;  // Validated in Python: cv.Length(max=64)
+// Stack buffer size - safe because all inputs are length-validated at config time
+// Format: prefix + "/" + type + "/" + object_id + "/" + suffix + null
+static constexpr size_t MQTT_DEFAULT_TOPIC_MAX_LEN =
+    MQTT_TOPIC_PREFIX_MAX_LEN + 1 + MQTT_COMPONENT_TYPE_MAX_LEN + 1 + OBJECT_ID_MAX_LEN + 1 + MQTT_SUFFIX_MAX_LEN + 1;
 
-#define LOG_MQTT_COMPONENT(state_topic, command_topic) \
-  if (state_topic) { \
-    ESP_LOGCONFIG(TAG, "  State Topic: '%s'", this->get_state_topic_().c_str()); \
-  } \
-  if (command_topic) { \
-    ESP_LOGCONFIG(TAG, "  Command Topic: '%s'", this->get_command_topic_().c_str()); \
-  }
+class MQTTComponent;  // Forward declaration
+void log_mqtt_component(const char *tag, MQTTComponent *obj, bool state_topic, bool command_topic);
+
+#define LOG_MQTT_COMPONENT(state_topic, command_topic) log_mqtt_component(TAG, this, state_topic, command_topic)
 
 // Macro to define component_type() with compile-time length verification
 // Usage: MQTT_COMPONENT_TYPE(MQTTSensorComponent, "sensor")
@@ -74,6 +79,8 @@ static constexpr size_t MQTT_SUFFIX_MAX_LEN = 32;
  * a clean separation.
  */
 class MQTTComponent : public Component {
+  friend void log_mqtt_component(const char *tag, MQTTComponent *obj, bool state_topic, bool command_topic);
+
  public:
   /// Constructs a MQTTComponent.
   explicit MQTTComponent();
@@ -81,8 +88,6 @@ class MQTTComponent : public Component {
   /// Override setup_ so that we can call send_discovery() when needed.
   void call_setup() override;
 
-  void call_loop() override;
-
   void call_dump_config() override;
 
   /// Send discovery info the Home Assistant, override this.
@@ -90,7 +95,8 @@ class MQTTComponent : public Component {
 
   virtual bool send_initial_state() = 0;
 
-  virtual bool is_internal();
+  /// Returns cached is_internal result (computed once during setup).
+  bool is_internal() const { return this->is_internal_; }
 
   /// Set QOS for state messages.
   void set_qos(uint8_t qos);
@@ -133,6 +139,9 @@ class MQTTComponent : public Component {
   /// Internal method for the MQTT client base to schedule a resend of the state on reconnect.
   void schedule_resend_state();
 
+  /// Process pending resend if needed (called by MQTTClientComponent)
+  void process_resend();
+
   /** Send a MQTT message.
    *
    * @param topic The topic.
@@ -148,6 +157,38 @@ class MQTTComponent : public Component {
    */
   bool publish(const std::string &topic, const char *payload, size_t payload_length);
 
+  /** Send a MQTT message (no heap allocation for topic).
+   *
+   * @param topic The topic as C string.
+   * @param payload The payload buffer.
+   * @param payload_length The length of the payload.
+   */
+  bool publish(const char *topic, const char *payload, size_t payload_length);
+
+  /** Send a MQTT message (no heap allocation for topic).
+   *
+   * @param topic The topic as StringRef (for use with get_state_topic_to_()).
+   * @param payload The payload buffer.
+   * @param payload_length The length of the payload.
+   */
+  bool publish(StringRef topic, const char *payload, size_t payload_length) {
+    return this->publish(topic.c_str(), payload, payload_length);
+  }
+
+  /** Send a MQTT message (no heap allocation for topic).
+   *
+   * @param topic The topic as C string.
+   * @param payload The null-terminated payload.
+   */
+  bool publish(const char *topic, const char *payload);
+
+  /** Send a MQTT message (no heap allocation for topic).
+   *
+   * @param topic The topic as StringRef (for use with get_state_topic_to_()).
+   * @param payload The null-terminated payload.
+   */
+  bool publish(StringRef topic, const char *payload) { return this->publish(topic.c_str(), payload); }
+
   /** Construct and send a JSON MQTT message.
    *
    * @param topic The topic.
@@ -155,6 +196,20 @@ class MQTTComponent : public Component {
    */
   bool publish_json(const std::string &topic, const json::json_build_t &f);
 
+  /** Construct and send a JSON MQTT message (no heap allocation for topic).
+   *
+   * @param topic The topic as C string.
+   * @param f The Json Message builder.
+   */
+  bool publish_json(const char *topic, const json::json_build_t &f);
+
+  /** Construct and send a JSON MQTT message (no heap allocation for topic).
+   *
+   * @param topic The topic as StringRef (for use with get_state_topic_to_()).
+   * @param f The Json Message builder.
+   */
+  bool publish_json(StringRef topic, const json::json_build_t &f) { return this->publish_json(topic.c_str(), f); }
+
   /** Subscribe to a MQTT topic.
    *
    * @param topic The topic. Wildcards are currently not supported.
@@ -178,7 +233,16 @@ class MQTTComponent : public Component {
   /// Helper method to get the discovery topic for this component.
   std::string get_discovery_topic_(const MQTTDiscoveryInfo &discovery_info) const;
 
-  /** Get this components state/command/... topic.
+  /** Get this components state/command/... topic into a buffer.
+   *
+   * @param buf The buffer to write to (must be exactly MQTT_DEFAULT_TOPIC_MAX_LEN).
+   * @param suffix The suffix/key such as "state" or "command".
+   * @return StringRef pointing to the buffer with the topic.
+   */
+  StringRef get_default_topic_for_to_(std::span<char, MQTT_DEFAULT_TOPIC_MAX_LEN> buf, const char *suffix,
+                                      size_t suffix_len) const;
+
+  /** Get this components state/command/... topic (allocates std::string).
    *
    * @param suffix The suffix/key such as "state" or "command".
    * @return The full topic.
@@ -199,10 +263,20 @@ class MQTTComponent : public Component {
   /// Get whether the underlying Entity is disabled by default
   bool is_disabled_by_default_() const;
 
-  /// Get the MQTT topic that new states will be shared to.
+  /// Get the MQTT state topic into a buffer (no heap allocation for non-lambda custom topics).
+  /// @param buf Buffer of exactly MQTT_DEFAULT_TOPIC_MAX_LEN bytes.
+  /// @return StringRef pointing to the topic in the buffer.
+  StringRef get_state_topic_to_(std::span<char, MQTT_DEFAULT_TOPIC_MAX_LEN> buf) const;
+
+  /// Get the MQTT command topic into a buffer (no heap allocation for non-lambda custom topics).
+  /// @param buf Buffer of exactly MQTT_DEFAULT_TOPIC_MAX_LEN bytes.
+  /// @return StringRef pointing to the topic in the buffer.
+  StringRef get_command_topic_to_(std::span<char, MQTT_DEFAULT_TOPIC_MAX_LEN> buf) const;
+
+  /// Get the MQTT topic that new states will be shared to (allocates std::string).
   std::string get_state_topic_() const;
 
-  /// Get the MQTT topic for listening to commands.
+  /// Get the MQTT topic for listening to commands (allocates std::string).
   std::string get_command_topic_() const;
 
   bool is_connected_() const;
@@ -220,12 +294,18 @@ class MQTTComponent : public Component {
 
   std::unique_ptr<Availability> availability_;
 
-  bool command_retain_{false};
-  bool retain_{true};
-  uint8_t qos_{0};
-  uint8_t subscribe_qos_{0};
-  bool discovery_enabled_{true};
-  bool resend_state_{false};
+  // Packed bitfields - QoS values are 0-2, bools are flags
+  uint8_t qos_ : 2 {0};
+  uint8_t subscribe_qos_ : 2 {0};
+  bool command_retain_ : 1 {false};
+  bool retain_ : 1 {true};
+  bool discovery_enabled_ : 1 {true};
+  bool resend_state_ : 1 {false};
+  bool is_internal_ : 1 {false};  ///< Cached result of compute_is_internal_(), set during setup
+
+  /// Compute is_internal status based on topics and entity state.
+  /// Called once during setup to cache the result.
+  bool compute_is_internal_();
 };
 
 }  // namespace esphome::mqtt

esphome/components/mqtt/mqtt_cover.cpp

@@ -51,7 +51,7 @@ void MQTTCoverComponent::dump_config() {
   ESP_LOGCONFIG(TAG, "MQTT cover '%s':", this->cover_->get_name().c_str());
   auto traits = this->cover_->get_traits();
   bool has_command_topic = traits.get_supports_position() || !traits.get_supports_tilt();
-  LOG_MQTT_COMPONENT(true, has_command_topic)
+  LOG_MQTT_COMPONENT(true, has_command_topic);
   if (traits.get_supports_position()) {
     ESP_LOGCONFIG(TAG,
                   "  Position State Topic: '%s'\n"
@@ -115,7 +115,8 @@ bool MQTTCoverComponent::publish_state() {
                         : this->cover_->position == COVER_OPEN                       ? "open"
                         : traits.get_supports_position()                             ? "open"
                                                                                      : "unknown";
-  if (!this->publish(this->get_state_topic_(), state_s))
+  char topic_buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
+  if (!this->publish(this->get_state_topic_to_(topic_buf), state_s))
     success = false;
   return success;
 }

esphome/components/mqtt/mqtt_date.cpp

@@ -36,7 +36,7 @@ void MQTTDateComponent::setup() {
 
 void MQTTDateComponent::dump_config() {
   ESP_LOGCONFIG(TAG, "MQTT Date '%s':", this->date_->get_name().c_str());
-  LOG_MQTT_COMPONENT(true, true)
+  LOG_MQTT_COMPONENT(true, true);
 }
 
 MQTT_COMPONENT_TYPE(MQTTDateComponent, "date")
@@ -53,7 +53,8 @@ bool MQTTDateComponent::send_initial_state() {
   }
 }
 bool MQTTDateComponent::publish_state(uint16_t year, uint8_t month, uint8_t day) {
-  return this->publish_json(this->get_state_topic_(), [year, month, day](JsonObject root) {
+  char topic_buf[MQTT_DEFAULT_TOPIC_MAX_LEN];
+  return this->publish_json(this->get_state_topic_to_(topic_buf), [year, month, day](JsonObject root) {
     // NOLINTNEXTLINE(clang-analyzer-cplusplus.NewDeleteLeaks) false positive with ArduinoJson
     root[ESPHOME_F("year")] = year;
     root[ESPHOME_F("month")] = month;