Simulate the unreadable partitions.csv instead of chmod

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: J. Nick Koston <nick@koston.org>

.claude/settings.json

@@ -0,0 +1,16 @@
+{
+  "hooks": {
+    "SessionStart": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "d=\"${CLAUDE_PROJECT_DIR:-.}\"; [ -x \"$d/venv/bin/python\" ] || { mkdir -p \"$d/.temp\"; env -u VIRTUAL_ENV \"$d/script/setup\" >\"$d/.temp/setup.log\" 2>&1 || echo '{\"systemMessage\":\"script/setup failed; see .temp/setup.log\"}'; }",
+            "statusMessage": "Setting up dev environment (script/setup)...",
+            "timeout": 900
+          }
+        ]
+      }
+    ]
+  }
+}

.github/workflows/ci-docker.yml

@@ -119,16 +119,22 @@ jobs:
       # pushed image) keeps it working for fork PRs, which never push to ghcr.io.
       - name: Export image for compile-test
         if: matrix.os == 'ubuntu-24.04' && matrix.build_type == 'docker'
-        run: docker save "ghcr.io/esphome/esphome-amd64:${{ steps.tag.outputs.tag }}" | gzip > compile-test-image.tar.gz
+        # zstd over gzip: docker save is on the critical path for every
+        # compile-test job, and zstd -T0 is multithreaded (export 50s -> 9s).
+        # docker load auto-detects the format; its time is layer extraction,
+        # not decompression, so it is unchanged. shell: bash adds pipefail so
+        # a failed docker save cannot upload a truncated artifact.
+        shell: bash
+        run: docker save "ghcr.io/esphome/esphome-amd64:${{ steps.tag.outputs.tag }}" | zstd -T0 -3 > compile-test-image.tar.zst
 
       - name: Upload compile-test image artifact
         if: matrix.os == 'ubuntu-24.04' && matrix.build_type == 'docker'
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
-          # The tar is already gzipped, so upload it as-is. archive: false skips
-          # the redundant zip and makes the file name the artifact name (the
-          # `name` input is ignored in that mode).
-          path: compile-test-image.tar.gz
+          # The tar is already compressed, so upload it as-is. archive: false
+          # skips the redundant zip and makes the file name the artifact name
+          # (the `name` input is ignored in that mode).
+          path: compile-test-image.tar.zst
           retention-days: 1
           archive: false
 
@@ -182,8 +188,6 @@ jobs:
       contents: read  # actions/checkout to load the test configs
     strategy:
       fail-fast: false
-      # Modest cap so this smoke test leaves room on the shared runner pool.
-      max-parallel: 8
       matrix:
         # One entry per distinct toolchain. ESP32 variants (c3/c6/s2/s3/p4)
         # share a toolchain bundle, so esp32 is exercised on the base variant
@@ -208,9 +212,9 @@ jobs:
       - name: Download image artifact
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
-          name: compile-test-image.tar.gz
+          name: compile-test-image.tar.zst
       - name: Load image
-        run: docker load --input compile-test-image.tar.gz
+        run: docker load --input compile-test-image.tar.zst
       - name: Compile ${{ matrix.id }}
         run: |
           docker run --rm \

.github/workflows/ci.yml

@@ -112,6 +112,12 @@ jobs:
       component-test-batches: ${{ steps.determine.outputs.component-test-batches }}
       validate-only-components: ${{ steps.determine.outputs.validate-only-components }}
       benchmarks: ${{ steps.determine.outputs.benchmarks }}
+      # "true" when this run is a pull request into one of the release
+      # branches. Those pull requests are batches of changes already tested on
+      # their original dev pull requests, so several jobs below trade coverage
+      # for turnaround time on them. Matched exactly, not by prefix, so an
+      # ordinary branch named e.g. "release-notes" is not caught by it.
+      release-pr: ${{ github.base_ref == 'beta' || github.base_ref == 'release' }}
     steps:
       - name: Check out code from GitHub
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -230,7 +236,7 @@ jobs:
     runs-on: ubuntu-latest
     needs:
       - determine-jobs
-    if: github.event_name == 'pull_request' && !startsWith(github.base_ref, 'beta') && !startsWith(github.base_ref, 'release') && needs.determine-jobs.outputs.core-ci == 'true'
+    if: github.event_name == 'pull_request' && needs.determine-jobs.outputs.release-pr == 'false' && needs.determine-jobs.outputs.core-ci == 'true'
     steps:
       - name: Check out code from GitHub
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -449,10 +455,21 @@ jobs:
     if: >-
       github.repository == 'esphome/esphome' && (
         (github.event_name == 'push' && github.ref_name == 'dev') ||
-        (github.event_name == 'pull_request' && needs.determine-jobs.outputs.benchmarks == 'true')
+        (
+          github.event_name == 'pull_request' &&
+          needs.determine-jobs.outputs.release-pr == 'false' &&
+          needs.determine-jobs.outputs.benchmarks == 'true'
+        )
       )
     # CodSpeed benchmarks require a CodSpeed account linked to the repository to run
     # (https://codspeed.io) -- disabled on forks that aren't esphome/esphome itself.
+    #
+    # Pull requests into beta and release are skipped as well. CodSpeed compares a
+    # pull request against the newest commit of its base branch that has a benchmark
+    # run of its own, and only dev is benchmarked. A release pull request therefore
+    # falls back to dev's latest run, so every speed-up merged into dev since the
+    # release branched is reported as a regression in the release. The changes there
+    # have already been benchmarked on their original dev pull requests.
     steps:
       - name: Check out code from GitHub
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -519,7 +536,7 @@ jobs:
             apt-get install -y libc6-dbg
 
       - name: Run CodSpeed benchmarks
-        uses: CodSpeedHQ/action@4296e51e7041e24dadb86d1d6e8b9320d223dbe8 # v5.0.3
+        uses: CodSpeedHQ/action@373d6868929f444bc08d901fd0eb0ad52a8875ea # v5.2.1
         with:
           run: |
             . venv/bin/activate
@@ -929,7 +946,6 @@ jobs:
       ESPHOME_SDK_NRF_PREFIX: ~/.esphome-sdk-nrf
     strategy:
       fail-fast: false
-      max-parallel: ${{ (startsWith(github.base_ref, 'beta') || startsWith(github.base_ref, 'release')) && 32 || 16 }}
       matrix:
         batch: ${{ fromJson(needs.determine-jobs.outputs.component-test-batches) }}
     steps:
@@ -1016,7 +1032,7 @@ jobs:
           # - This catches pin conflicts and other issues in directly changed code
           # - Grouped tests use --testing-mode to allow config merging (disables some checks)
           # - Dependencies are safe to group since they weren't modified in this PR
-          if [[ "${{ github.base_ref }}" == beta* ]] || [[ "${{ github.base_ref }}" == release* ]]; then
+          if [[ "${{ needs.determine-jobs.outputs.release-pr }}" == "true" ]]; then
             directly_changed_csv=""
             echo "Testing components: $components_csv"
             echo "Target branch: ${{ github.base_ref }} - grouping all components"

.github/workflows/codeql.yml

@@ -56,7 +56,7 @@ jobs:
 
       # Initializes the CodeQL tools for scanning.
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@ff2f1c621b7f889edc0d3c761ac2e6a3f8cdb0dd # v4.37.7
+        uses: github/codeql-action/init@db488ddef3bf6cb639b32c2e9a7c0a7ea8271d28 # v4.37.8
         with:
           languages: ${{ matrix.language }}
           build-mode: ${{ matrix.build-mode }}
@@ -84,6 +84,6 @@ jobs:
           exit 1
 
       - name: Perform CodeQL Analysis
-        uses: github/codeql-action/analyze@ff2f1c621b7f889edc0d3c761ac2e6a3f8cdb0dd # v4.37.7
+        uses: github/codeql-action/analyze@db488ddef3bf6cb639b32c2e9a7c0a7ea8271d28 # v4.37.8
         with:
           category: "/language:${{matrix.language}}"

CODEOWNERS

@@ -381,6 +381,7 @@ esphome/components/nextion/switch/* @senexcrenshaw
 esphome/components/nextion/text_sensor/* @senexcrenshaw
 esphome/components/nfc/* @jesserockz @kbx81
 esphome/components/noblex/* @AGalfra
+esphome/components/noise/* @esphome/core
 esphome/components/npi19/* @bakerkj
 esphome/components/nrf52/* @tomaszduda23
 esphome/components/number/* @esphome/core
@@ -475,6 +476,7 @@ esphome/components/sensirion_common/* @martgras
 esphome/components/sensor/* @esphome/core
 esphome/components/serial_proxy/* @kbx81
 esphome/components/sfa30/* @ghsensdev
+esphome/components/sfa40/* @NoQuarrel
 esphome/components/sgp40/* @SenexCrenshaw
 esphome/components/sgp4x/* @martgras @SenexCrenshaw
 esphome/components/sha256/* @esphome/core
@@ -575,6 +577,7 @@ esphome/components/tuya/select/* @bearpawmaxim
 esphome/components/tuya/sensor/* @jesserockz
 esphome/components/tuya/switch/* @jesserockz
 esphome/components/tuya/text_sensor/* @dentra
+esphome/components/tuya/water_heater/* @iago-veiga
 esphome/components/uart/* @esphome/core
 esphome/components/uart/button/* @ssieb
 esphome/components/uart/event/* @eoasmxd

docker/Dockerfile

@@ -22,7 +22,7 @@ RUN \
     -r /requirements.txt
 
 # Install the ESPHome Device Builder dashboard.
-RUN uv pip install --no-cache-dir esphome-device-builder==1.12.4
+RUN uv pip install --no-cache-dir esphome-device-builder==1.13.1
 
 RUN \
     platformio settings set enable_telemetry No \

esphome/__main__.py

@@ -857,7 +857,20 @@ def compile_program(args: ArgsProtocol, config: ConfigType) -> int:
         toolchain.create_factory_bin()
         toolchain.create_ota_bin()
         toolchain.create_elf_copy()
-        toolchain.get_idedata()
+        from esphome.build_helpers.idedata import IDEDATA_BEST_EFFORT_ERRORS
+
+        try:
+            if toolchain.get_idedata() is None:
+                _LOGGER.warning("No idedata was generated for this build")
+        except IDEDATA_BEST_EFFORT_ERRORS as err:
+            # The firmware already built; an idedata failure must not fail
+            # a successful build.
+            _LOGGER.warning(
+                "Could not generate idedata: %s (IDE, clang-tidy, and "
+                "memory-analysis data will be unavailable for this build)",
+                err,
+            )
+            _LOGGER.debug("Idedata failure detail", exc_info=True)
     else:
         from esphome.platformio import toolchain
 
@@ -2721,10 +2734,14 @@ def run_esphome(argv):
     # Skipped when -s overrides are passed, since the cache was written
     # against the previous substitution set.
     config: ConfigType | None = None
-    cache_eligible = (
+    cache_write_eligible = (
         args.command in ("upload", "logs") and not command_line_substitutions
     )
-    if cache_eligible:
+    # An explicit --toolchain must re-run the per-platform validators, so
+    # gate only the cache read; the refresh below saves the result unless
+    # the sidecar records a different toolchain.
+    cache_read_eligible = cache_write_eligible and args.toolchain is None
+    if cache_read_eligible:
         from esphome.compiled_config import load_compiled_config
 
         config = load_compiled_config(conf_path)
@@ -2748,17 +2765,14 @@ def run_esphome(argv):
             return 2
     CORE.config = config
 
-    # Fallback for platforms whose validators didn't set the toolchain
-    # (only the esp32 component reads esp32.framework.toolchain). All
-    # other platforms only support PlatformIO today. Must run before the
-    # cache refresh below so its sidecar records the same toolchain a
-    # compile would.
+    # The cache fast path skips validation, and legacy sidecars lack the
+    # toolchain field. Must run before the cache refresh below.
     if CORE.toolchain is None:
         CORE.toolchain = Toolchain.PLATFORMIO
 
     # Refresh the cache so the next upload/logs hits the fast path
     # instead of re-running read_config.
-    if cache_eligible and cache_missed:
+    if cache_write_eligible and cache_missed:
         from esphome.compiled_config import save_compiled_config_and_sidecar
 
         save_compiled_config_and_sidecar(config)

esphome/arduino8266/__init__.py

@@ -0,0 +1,9 @@
+"""Native (PlatformIO-free) build support for the ESP8266 Arduino core.
+
+This package downloads the Arduino ESP8266 core and the xtensa-lx106
+toolchain, generates a ninja build for them plus the ESPHome sources, and
+drives the build directly — the ESP8266 equivalent of ``esphome.espidf``.
+
+Deliberately importable without the esp8266 component to avoid circular
+imports; the component wires these modules in via lazy imports.
+"""

esphome/arduino8266/framework.py

@@ -0,0 +1,164 @@
+"""Download and install the Arduino ESP8266 core, toolchain, and ninja.
+
+Artifacts land in a machine-global cache (shared across projects, like the
+ESP-IDF install in ``esphome.espidf.framework``):
+
+    <cache>/arduino8266/frameworks/<version>/   framework-arduinoespressif8266
+    <cache>/arduino8266/toolchains/<version>/   toolchain-xtensa (gcc 10.3)
+
+Packages come from the PlatformIO registry (identical bits to the PlatformIO
+backend); ``ESPHOME_ARDUINO8266_*_MIRRORS`` overrides the URLs. ninja comes
+from PATH or the ninja PyPI wheel.
+"""
+
+from __future__ import annotations
+
+import os
+from pathlib import Path
+from typing import NamedTuple
+
+from esphome.build_helpers.ccache import ccache_defaults_env
+from esphome.build_helpers.ninja import find_ninja
+from esphome.build_helpers.tools_cache import ARDUINO8266_TOOLS_CACHE, tools_cache_path
+from esphome.core import EsphomeError, Version
+from esphome.framework_helpers import str_to_lst_of_str
+from esphome.platformio.registry import install_package, prefetch_packages
+
+FRAMEWORK_PACKAGE = "framework-arduinoespressif8266"
+TOOLCHAIN_PACKAGE = "toolchain-xtensa"
+# gcc 10.3, the toolchain Arduino core 3.x builds with; the build
+# generator's compile flags are tuned to it.
+TOOLCHAIN_VERSION = "2.100300.220621"
+
+ESPHOME_ARDUINO8266_FRAMEWORK_MIRRORS = str_to_lst_of_str(
+    os.environ.get("ESPHOME_ARDUINO8266_FRAMEWORK_MIRRORS", "")
+)
+ESPHOME_ARDUINO8266_TOOLCHAIN_MIRRORS = str_to_lst_of_str(
+    os.environ.get("ESPHOME_ARDUINO8266_TOOLCHAIN_MIRRORS", "")
+)
+
+
+def get_arduino8266_tools_path() -> Path:
+    # Machine-global so all projects share one install; see
+    # espidf.framework.get_idf_tools_path for the location rationale.
+    return tools_cache_path(*ARDUINO8266_TOOLS_CACHE)
+
+
+# 3.1.1 rather than 3.1.0: the registry has no package for 3.1.0, and the
+# encoder below cannot name 3.0.0/3.0.1 either (see its docstring)
+MIN_FRAMEWORK_VERSION = Version(3, 1, 1)
+
+
+def framework_package_version(ver: Version) -> str:
+    """Map an Arduino core version to its registry package version (3.1.2 ->
+    3.30102.0; the leading 3 is the package major).
+
+    Exact registry names only for cores > 2.6.2 and >= 3.0.2; callers floor
+    at MIN_FRAMEWORK_VERSION.
+    """
+    if ver.major > 3:
+        raise EsphomeError(
+            f"Arduino core {ver} is not supported yet; "
+            "the newest known core series is 3.x"
+        )
+    if ver <= Version(2, 6, 2):
+        # Cores <= 2.6.2 use the older 1.x/2.x package-major encodings (same
+        # boundary as _format_framework_arduino_version's era guard)
+        raise EsphomeError(
+            f"Arduino core {ver} uses an older package encoding than this "
+            "helper implements (newer than 2.6.2)"
+        )
+    return f"3.{ver.major}{ver.minor:02d}{ver.patch:02d}.0"
+
+
+def get_framework_path(package_version: str) -> Path:
+    return get_arduino8266_tools_path() / "frameworks" / package_version
+
+
+def get_toolchain_path() -> Path:
+    return get_arduino8266_tools_path() / "toolchains" / TOOLCHAIN_VERSION
+
+
+class InstalledPaths(NamedTuple):
+    """Locations of the installed framework, toolchain, and ninja binary."""
+
+    framework: Path
+    toolchain: Path
+    ninja: Path
+
+
+def check_and_install(framework_version: Version) -> InstalledPaths:
+    """Ensure framework, toolchain, and ninja are installed; return their paths."""
+    if framework_version < MIN_FRAMEWORK_VERSION:
+        # Config validation enforces this too; keep the module honest when
+        # called directly.
+        raise EsphomeError(
+            f"The native toolchain requires the Arduino core "
+            f">= {MIN_FRAMEWORK_VERSION}, got {framework_version}"
+        )
+    # Probe the cheap local dependency before ~110 MB of downloads
+    ninja_path = find_ninja()
+    package_version = framework_package_version(framework_version)
+    framework_path = get_framework_path(package_version)
+    downloads_dir = get_arduino8266_tools_path() / "downloads"
+    toolchain_path = get_toolchain_path()
+    # One spec per package: the prefetch and the installs must agree
+    specs = (
+        (
+            FRAMEWORK_PACKAGE,
+            package_version,
+            framework_path,
+            ESPHOME_ARDUINO8266_FRAMEWORK_MIRRORS,
+            ("cores/esp8266", "tools/sdk", "libraries"),
+        ),
+        (
+            TOOLCHAIN_PACKAGE,
+            TOOLCHAIN_VERSION,
+            toolchain_path,
+            ESPHOME_ARDUINO8266_TOOLCHAIN_MIRRORS,
+            # xtensa-lx106-elf pins the target: every gcc package has a bin/
+            ("bin", "xtensa-lx106-elf"),
+        ),
+    )
+    # Fetch both archives at once; the installs below verify and extract
+    prefetch_packages([spec[:4] for spec in specs], downloads_dir)
+    for name, version, dest, mirrors, expect in specs:
+        install_package(name, version, dest, mirrors, downloads_dir, expect=expect)
+    return InstalledPaths(
+        framework=framework_path, toolchain=toolchain_path, ninja=ninja_path
+    )
+
+
+def toolchain_tool(toolchain_path: Path, name: str) -> Path:
+    """Path to one toolchain tool (gcc, g++, ar, size, addr2line, ...).
+
+    The single owner of the ``bin/xtensa-lx106-elf-<name>`` layout and the
+    Windows suffix, so a toolchain package bump touches one spot.
+    """
+    suffix = ".exe" if os.name == "nt" else ""
+    return toolchain_path / "bin" / f"xtensa-lx106-elf-{name}{suffix}"
+
+
+def get_build_env(toolchain_path: Path, ccache: str | None) -> dict[str, str]:
+    env = os.environ.copy()
+    # Drop empty entries: a trailing separator from an absent PATH would
+    # make the shell search the current directory for tools
+    parts = [
+        str(toolchain_path / "bin"),
+        *filter(None, env.get("PATH", "").split(os.pathsep)),
+    ]
+    env["PATH"] = os.pathsep.join(parts)
+    env.update(ccache_env(ccache))
+    return env
+
+
+def ccache_env(ccache: str | None) -> dict[str, str]:
+    """Return ccache settings for the build subprocess (not os.environ).
+
+    ``ccache`` is the pre-resolved binary (resolve_ccache_path), or None
+    when disabled. Values the user already set in the environment are
+    respected.
+    """
+    if ccache is None:
+        return {}
+    return ccache_defaults_env(get_arduino8266_tools_path() / "ccache")

esphome/build_gen/espidf.py

@@ -1,6 +1,7 @@
 """ESP-IDF direct build generator for ESPHome."""
 
 import json
+import logging
 from pathlib import Path
 
 from esphome.components.esp32 import (
@@ -11,6 +12,7 @@ from esphome.components.esp32 import (
 )
 import esphome.config_validation as cv
 from esphome.core import CORE
+from esphome.espidf import variant_to_idf_target
 from esphome.framework_helpers import (
     get_project_compile_flags,
     get_project_cxx_compile_flags,
@@ -18,6 +20,8 @@ from esphome.framework_helpers import (
 )
 from esphome.helpers import mkdir_p, write_file_if_changed
 
+_LOGGER = logging.getLogger(__name__)
+
 # Replaces the IDF default C++ standard (-std=gnu++2b appended to
 # CXX_COMPILE_OPTIONS by project.cmake's __build_init) with the one set via
 # cg.set_cpp_standard(). Emitted between include(project.cmake) and project(),
@@ -31,11 +35,12 @@ idf_build_set_property(CXX_COMPILE_OPTIONS "${{esphome_cxx_compile_options}}")""
 
 
 def get_available_components() -> list[str] | None:
-    """Get list of built-in ESP-IDF components from project_description.json.
+    """List the built-in ESP-IDF components from ``project_description.json``.
 
-    Excludes ``src``, IDF-managed components (``managed_components/``), and
-    converted PIO libs (``pio_components/``). Returns ``None`` if the build
-    dir or ``project_description.json`` isn't ready yet.
+    Only components below its ``idf_path/components`` count, which leaves out
+    ``src``, IDF-managed components, converted PIO libs and project local
+    ones such as the Arduino ``component_stubs``. Returns ``None`` if the
+    build dir or ``project_description.json`` isn't ready yet.
     """
     if CORE.build_path is None:
         return None
@@ -46,30 +51,24 @@ def get_available_components() -> list[str] | None:
     try:
         with project_desc.open(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 IDF-managed and converted-PIO components (external).
-            comp_dir = info.get("dir", "")
-            if "managed_components" in comp_dir or "pio_components" in comp_dir:
-                continue
-
-            result.append(name)
-
-        return result
-    except (json.JSONDecodeError, OSError):
+        root = (Path(data["idf_path"]) / "components").resolve()
+        result = [
+            name
+            for name, info in data.get("build_component_info", {}).items()
+            if (comp_dir := info.get("dir"))
+            and Path(comp_dir).resolve().is_relative_to(root)
+        ]
+    except (json.JSONDecodeError, KeyError, OSError) as err:
+        _LOGGER.debug("Could not read %s: %s", project_desc, err)
         return None
+    if not result:
+        _LOGGER.warning("No ESP-IDF components found under %s", root)
+    return result
 
 
 def has_discovered_components() -> bool:
-    """Check if we have discovered components from a previous configure."""
-    return get_available_components() is not None
+    """Check if a previous configure discovered any built-in components."""
+    return bool(get_available_components())
 
 
 def _cmake_quote(value: str) -> str:
@@ -79,19 +78,22 @@ def _cmake_quote(value: str) -> str:
     return f'"{escaped}"'
 
 
-def get_project_cmakelists(minimal: bool = False) -> str:
+def get_project_cmakelists(
+    minimal: bool = False, builtin_components: list[str] | None = None
+) -> str:
     """Generate the top-level CMakeLists.txt for ESP-IDF project.
 
     When ``minimal`` is true, omit ``ESPHOME_PROJECT_BUILTIN_COMPONENTS``
     since ``project_description.json`` may be stale on the first write.
+    ``builtin_components`` supplies the discovered list (from the cache)
+    instead of reading it from ``project_description.json``.
     """
-    # Get IDF target from ESP32 variant (e.g., ESP32S3 -> esp32s3)
-    variant = get_esp32_variant()
-    idf_target = variant.lower().replace("-", "")
+    idf_target = variant_to_idf_target(get_esp32_variant())
 
-    # esp_idf_size 2.x (bundled with IDF >=6.0) made NG the default and
-    # removed the --ng flag; on 1.x (IDF 5.5) --ng is required to get
-    # --format=raw because the legacy mode doesn't support it.
+    # esp_idf_size 2.x (IDF >=6.0) made NG the default and removed --ng;
+    # 1.x (IDF 5.5) needs --ng for --format=json2. 1.x json2 also lacks
+    # total_size, hence the ELF fallback in espidf/size_summary.py; both
+    # go away together when 1.x support is dropped.
     size_ng_flag = "--ng" if idf_version() < cv.Version(6, 0, 0) else ""
 
     # Project-wide compile options: -D defines and -W warning flags (skip
@@ -162,9 +164,11 @@ def get_project_cmakelists(minimal: bool = False) -> str:
         else "\n".join(
             f"idf_build_set_property(ESPHOME_PROJECT_BUILTIN_COMPONENTS {name} APPEND)"
             for name in sorted(
-                set(get_available_components() or []).difference(
-                    CORE.cmake_args.get("EXCLUDE_COMPONENTS", "").split(";")
-                )
+                set(
+                    builtin_components
+                    if builtin_components is not None
+                    else get_available_components() or []
+                ).difference(CORE.cmake_args.get("EXCLUDE_COMPONENTS", "").split(";"))
             )
         )
     )
@@ -208,10 +212,12 @@ include($ENV{{IDF_PATH}}/tools/cmake/project.cmake)
 
 project({CORE.name})
 
-# Emit raw JSON size data for ESPHome to read post-build.
+# Emit per-memory-type JSON size data for ESPHome to read post-build.
+# json2 stays small; raw dumps every symbol (~2s on a large map) and
+# this command runs inside the link edge, blocking everything downstream.
 add_custom_command(
     TARGET ${{CMAKE_PROJECT_NAME}}.elf POST_BUILD
-    COMMAND ${{PYTHON}} -m esp_idf_size {size_ng_flag} --format=raw
+    COMMAND ${{PYTHON}} -m esp_idf_size {size_ng_flag} --format=json2
             -o ${{CMAKE_BINARY_DIR}}/esp_idf_size.json
             ${{CMAKE_PROJECT_NAME}}.map
     WORKING_DIRECTORY ${{CMAKE_BINARY_DIR}}
@@ -279,7 +285,9 @@ target_link_options(${{COMPONENT_LIB}} PUBLIC
 """
 
 
-def write_project(minimal: bool = False) -> None:
+def write_project(
+    minimal: bool = False, builtin_components: list[str] | None = None
+) -> None:
     """Write ESP-IDF project files."""
     mkdir_p(CORE.build_path)
     mkdir_p(CORE.relative_src_path())
@@ -287,7 +295,7 @@ def write_project(minimal: bool = False) -> None:
     # Write top-level CMakeLists.txt
     write_file_if_changed(
         CORE.relative_build_path("CMakeLists.txt"),
-        get_project_cmakelists(minimal=minimal),
+        get_project_cmakelists(minimal=minimal, builtin_components=builtin_components),
     )
 
     # Write component CMakeLists.txt in src/

esphome/build_helpers/__init__.py

@@ -0,0 +1 @@
+"""Build helpers shared by the native (non-PlatformIO) toolchains."""

esphome/build_helpers/ccache.py

@@ -0,0 +1,92 @@
+"""Shared ccache policy for build backends: env-knob parsing, binary
+resolution, and default ``CCACHE_*`` values."""
+
+from __future__ import annotations
+
+import logging
+import os
+from pathlib import Path
+
+from esphome.framework_helpers import strip_win_long_path_prefix, tool_version_runs
+from esphome.helpers import FALSY_ENV_STRINGS, TRUTHY_ENV_STRINGS
+
+_LOGGER = logging.getLogger(__name__)
+
+
+def _ccache_runs(ccache: str) -> bool:
+    """Return True when the ``ccache`` found on PATH actually runs."""
+    return tool_version_runs(
+        ccache,
+        "Ignoring ccache at %s because it failed to run; compiling without ccache",
+    )
+
+
+def parse_enable_env(name: str) -> bool | None:
+    """Strictly parse an on/off environment knob; None when unset or invalid.
+
+    ``bool(str)`` truthiness would flip ``no``/``off`` to enabled, so only
+    1/true/yes/on and 0/false/no/off count; anything else warns and reads
+    as unset so the caller's default policy applies.
+    """
+    raw = os.environ.get(name)
+    if raw is None:
+        return None
+    lowered = raw.strip().lower()
+    if not lowered:
+        # ENV KNOB= (Docker/CI) has always read as a disable
+        return False
+    if lowered in TRUTHY_ENV_STRINGS:
+        return True
+    if lowered in FALSY_ENV_STRINGS:
+        return False
+    _LOGGER.warning("Ignoring unrecognized %s=%r; use 1 or 0", name, raw)
+    return None
+
+
+def resolve_ccache_path() -> str | None:
+    """The ccache binary to wrap compiles with, or None when disabled.
+
+    An explicit ``ESPHOME_CCACHE_ENABLE=1`` skips the runnability probe; the
+    Windows extended-length prefix is stripped before probing (#18399).
+    """
+    import shutil
+
+    explicit = parse_enable_env("ESPHOME_CCACHE_ENABLE")
+    if explicit is False:
+        return None
+    ccache = shutil.which("ccache")
+    if ccache is None:
+        if explicit:
+            _LOGGER.warning(
+                "ESPHOME_CCACHE_ENABLE is set but no ccache binary is on PATH; "
+                "compiling without ccache"
+            )
+        return None
+    ccache = strip_win_long_path_prefix(ccache)
+    if not explicit and not _ccache_runs(ccache):
+        return None
+    return ccache
+
+
+def ccache_defaults_env(cache_dir: Path) -> dict[str, str]:
+    """Default ``CCACHE_*`` values for a build subprocess (not os.environ).
+
+    Values the user already set in the environment are respected. Depend
+    mode is on: both native backends emit depfiles (-MMD / CMake), which
+    keeps cache-miss overhead low.
+    """
+    from esphome.core import CORE
+
+    # An unset build_path means the env was built before preload; fail loudly
+    # rather than silently drop CCACHE_BASEDIR.
+    if CORE.build_path is None:
+        raise ValueError(
+            "CORE.build_path must be set before constructing the build environment"
+        )
+    defaults = {
+        "CCACHE_DIR": str(cache_dir),
+        "CCACHE_NOHASHDIR": "true",
+        "CCACHE_DEPEND": "1",
+        "CCACHE_BASEDIR": str(Path(CORE.build_path).resolve()),
+    }
+    return {k: v for k, v in defaults.items() if k not in os.environ}

esphome/build_helpers/idedata.py

@@ -1,10 +1,10 @@
-"""Derive idedata from an ESP-IDF native-toolchain ``compile_commands.json``.
+"""Derive idedata from a native (non-PlatformIO) build's ``compile_commands.json``.
 
-PlatformIO exposes a curated ``pio run -t idedata`` JSON; the native ESP-IDF
-toolchain has no such command, but its CMake build emits
-``build/compile_commands.json`` (CMAKE_EXPORT_COMPILE_COMMANDS). This module
-turns that file into the same fields consumers (IDE integration, clang-tidy)
-expect:
+PlatformIO exposes a curated ``pio run -t idedata`` JSON; the native
+toolchains have no such command, but each build produces a
+``compile_commands.json`` (CMAKE_EXPORT_COMPILE_COMMANDS for ESP-IDF, ninja's
+compdb tool otherwise). This module turns that file into the same fields
+consumers (IDE integration, clang-tidy) expect:
 
     {cc_path, cxx_path, cxx_flags, defines, includes: {build, toolchain}}
 """
@@ -18,6 +18,19 @@ from pathlib import Path
 import shlex
 import subprocess
 
+from esphome.core import EsphomeError
+from esphome.helpers import write_file
+
+# Everything idedata generation may raise after a successful link; idedata
+# is a bonus artifact, so consumers warn instead of failing the build
+IDEDATA_BEST_EFFORT_ERRORS = (
+    EsphomeError,
+    LookupError,
+    OSError,
+    RuntimeError,
+    ValueError,
+)
+
 _LOGGER = logging.getLogger(__name__)
 
 # C++ translation-unit suffixes used to identify ESPHome source files.
@@ -30,12 +43,8 @@ _ESPHOME_SRC_MARKER = "/src/esphome/"
 
 
 def _is_esphome_src(file: str) -> bool:
-    """Whether ``file`` is an ESPHome C++ translation unit.
-
-    ``compile_commands.json`` ``file`` paths use the OS-native separator, so on
-    Windows they contain backslashes; normalize to ``/`` before testing the
-    marker, otherwise no source matches and the build-include union is empty.
-    """
+    """Whether ``file`` is an ESPHome C++ translation unit; normalized to
+    ``/`` first since Windows compile DBs use backslashes."""
     return _ESPHOME_SRC_MARKER in file.replace("\\", "/") and file.endswith(
         _CXX_SUFFIXES
     )
@@ -106,11 +115,8 @@ def _expand_response_files(tokens: list[str], directory: Path) -> list[str]:
 
 
 def _pick_entry(entries: list[dict]) -> dict:
-    """Pick a representative ESPHome C++ translation unit.
-
-    All ESPHome sources share the same component flags/defines, so any one of
-    them yields the cxx_path / cxx_flags / defines we need.
-    """
+    """Pick a representative ESPHome C++ TU; all share the same component
+    flags/defines."""
     for entry in entries:
         if _is_esphome_src(entry["file"]):
             return entry
@@ -120,25 +126,46 @@ def _pick_entry(entries: list[dict]) -> dict:
     raise ValueError("no C++ translation unit found in compile_commands.json")
 
 
-def _parse_entry(entry: dict) -> tuple[str, list[str], list[str], list[str]]:
+# Compiler launchers that may prefix a compile command; a closed launcher
+# denylist beats enumerating compiler names, an open set.
+_LAUNCHER_STEMS = frozenset({"ccache", "sccache", "distcc", "icecc", "buildcache"})
+
+
+def _is_launcher(token: str) -> bool:
+    return Path(token).stem.lower() in _LAUNCHER_STEMS
+
+
+def parse_entry(
+    entry: dict, launcher: str | None = None
+) -> tuple[str, list[str], list[str], list[str]]:
     """Parse one compile_commands entry -> (cxx_path, defines, includes, cxx_flags)."""
     directory = Path(entry["directory"])
     tokens = _expand_response_files(_split_command(entry["command"]), directory)
 
     def _include(raw: str) -> str:
-        # Include paths in compile_commands are interpreted relative to the
-        # entry's ``directory`` (e.g. build-local ``-Iconfig``); resolve them
-        # so the cached idedata is usable regardless of the consumer's cwd.
-        # Emit forward slashes (``normpath`` yields ``\`` on Windows) so the
-        # paths match the absolute, already-forward-slash entries in the JSON.
+        # Resolve against the entry's ``directory`` so cached idedata works
+        # from any cwd; emit forward slashes to match the JSON's own entries
         raw = raw.strip()
         if raw and not Path(raw).is_absolute():
             raw = os.path.normpath(directory / raw)
         return raw.replace("\\", "/")
 
+    # A launcher-wrapped command ("ccache g++ ...") names the compiler second
+    if launcher is not None and tokens[:1] == [launcher]:
+        tokens = tokens[1:]
+    if not tokens:
+        # An empty command, or one that was only the launcher; fail by name
+        raise ValueError(f"empty compile command for {entry.get('file')}")
+    if _is_launcher(tokens[0]) and len(tokens) > 1 and not tokens[1].startswith("-"):
+        # Stale DB built with a launcher this run no longer configures; the
+        # real compiler is the next token
+        _LOGGER.warning("Stripping unconfigured launcher %s", tokens[0])
+        tokens = tokens[1:]
     # token0 is the compiler path; the rest of the command already uses forward
     # slashes on Windows, so normalize it too for a consistent idedata file.
     cxx_path = tokens[0].replace("\\", "/")
+    # Enforced here so no caller can record ccache as the compiler
+    reject_launcher_compiler(cxx_path)
     defines: list[str] = []
     includes: list[str] = []
     cxx_flags: list[str] = []
@@ -168,7 +195,7 @@ def _parse_entry(entry: dict) -> tuple[str, list[str], list[str], list[str]]:
     return cxx_path, defines, includes, cxx_flags
 
 
-def _get_toolchain_includes(cxx_path: str) -> list[str]:
+def get_toolchain_includes(cxx_path: str) -> list[str]:
     """Query the compiler for its builtin ``#include <...>`` search dirs."""
     result = subprocess.run(
         [cxx_path, "-E", "-x", "c++", "-", "-v"],
@@ -219,26 +246,128 @@ def _cc_path_from_cxx(cxx_path: str) -> str:
     return f"{stem}{suffix}"
 
 
-def idedata_from_build(compile_commands: Path) -> dict:
+def _cache_usable(cached: object) -> bool:
+    """Check a cached idedata dict against the guarantees of the write path.
+
+    Caches written by older versions predate the launcher rejection and the
+    include-union shape; serving one would bypass both. The dict check also
+    keeps "in" from substring-matching a bare JSON string.
+    """
+    if not isinstance(cached, dict) or "cc_path" not in cached:
+        return False
+    cxx_path = cached.get("cxx_path")
+    if not isinstance(cxx_path, str) or _is_launcher(cxx_path):
+        return False
+    includes = cached.get("includes")
+    return isinstance(includes, dict) and isinstance(includes.get("build"), list)
+
+
+def load_or_build_idedata(
+    compile_commands: Path,
+    elf_path: Path,
+    cache: Path,
+    launcher: str | None = None,
+) -> dict | None:
+    """Return idedata for a compile_commands.json build, cached on mtime.
+
+    Shared by the native ESP-IDF and ESP8266 Arduino toolchains. Returns None
+    when the compile DB doesn't exist yet (nothing was built). ``launcher``
+    is the compiler-launcher path (ccache) the build was generated with, if
+    any; commands in the compile DB are prefixed with it.
+    """
+    if not compile_commands.is_file():
+        _LOGGER.debug("No %s yet; skipping idedata generation", compile_commands)
+        return None
+
+    if cache.is_file() and cache.stat().st_mtime >= compile_commands.stat().st_mtime:
+        try:
+            cached = json.loads(cache.read_text(encoding="utf-8"))
+        except (ValueError, OSError) as err:
+            # A recurring cause (interrupted write, disk full) would otherwise
+            # look like unexplained slow builds
+            _LOGGER.warning("Discarding unreadable idedata cache %s: %s", cache, err)
+        else:
+            if _cache_usable(cached):
+                # Re-stamp so a relocated build dir cannot serve a stale ELF path
+                cached["prog_path"] = str(elf_path)
+                return cached
+            _LOGGER.debug("Regenerating idedata: cache %s fails validation", cache)
+
+    data = idedata_from_build(compile_commands, launcher)
+    data["prog_path"] = str(elf_path)
+    cache.parent.mkdir(parents=True, exist_ok=True)
+    # Atomic so a crash mid-write cannot leave a truncated cache
+    write_file(cache, json.dumps(data, indent=2) + "\n")
+    return data
+
+
+def reject_launcher_compiler(cxx_path: str) -> None:
+    """Reject a compile DB naming a launcher (ccache) as the compiler; it
+    must never be probed, cached, or consumed."""
+    if _is_launcher(cxx_path):
+        raise EsphomeError(
+            f"compile_commands.json names the launcher {cxx_path} as the "
+            "compiler; the compile database is unusable"
+        )
+
+
+def idedata_from_build(compile_commands: Path, launcher: str | None = None) -> dict:
     """Parse compile_commands.json into the idedata fields consumers expect.
 
-    A single ESP-IDF compile entry only carries its own component's REQUIRES
-    include set, but consumers (clang-tidy) analyze ESPHome headers that
-    transitively pull in other components. So take cxx_path / cxx_flags /
-    defines from a representative ESPHome TU, but union the include dirs across
-    all ESPHome TUs to get a project-wide superset (as PlatformIO's idedata
-    provides).
+    A single compile entry only carries the include set its own translation
+    unit was built with (per-component under ESP-IDF), but consumers
+    (clang-tidy) analyze ESPHome headers that transitively pull in other
+    components. So take cxx_path / cxx_flags / defines from a representative
+    ESPHome TU, but union the include dirs across all ESPHome TUs to get a
+    project-wide superset (as PlatformIO's idedata provides).
     """
     entries = json.loads(Path(compile_commands).read_text(encoding="utf-8"))
-    cxx_path, defines, _, cxx_flags = _parse_entry(_pick_entry(entries))
+    if not isinstance(entries, list) or not all(isinstance(e, dict) for e in entries):
+        # A TypeError here would escape IDEDATA_BEST_EFFORT_ERRORS
+        raise EsphomeError(f"{compile_commands} is not a compile-command list")
 
-    build_includes: dict[str, None] = {}
+    representative = _pick_entry(entries)
+    cxx_path, defines, rep_includes, cxx_flags = parse_entry(representative, launcher)
+
+    # Seed with the representative's includes so it is not parsed twice
+    has_esphome_tu = _is_esphome_src(representative["file"])
+    build_includes: dict[str, None] = dict.fromkeys(
+        rep_includes if has_esphome_tu else ()
+    )
+
+    def _shape(entry: dict) -> str:
+        # directory + command minus TU-specific paths: same shape means the
+        # same include set, so tokenize once per shape. Response-file
+        # commands never dedupe (the .rsp contents differ per object)
+        command = entry["command"]
+        directory = entry.get("directory", "")
+        if "@" in command:
+            return f"unique:{directory}|{entry.get('output') or command}"
+        stripped = command.replace(entry.get("file", ""), "").replace(
+            entry.get("output", ""), ""
+        )
+        return f"{directory}|{stripped}"
+
+    seen_shapes = {_shape(representative)}
     for entry in entries:
-        if not _is_esphome_src(entry["file"]):
+        if entry is representative or not _is_esphome_src(entry["file"]):
             continue
-        for inc in _parse_entry(entry)[2]:
+        has_esphome_tu = True
+        if (shape := _shape(entry)) in seen_shapes:
+            _LOGGER.debug("Include union: %s shares a command shape", entry["file"])
+            continue
+        seen_shapes.add(shape)
+        for inc in parse_entry(entry, launcher)[2]:
             build_includes.setdefault(inc, None)
 
+    if not has_esphome_tu:
+        # An arbitrary fallback TU breaks clang-tidy/IDE consumers, and a
+        # warning would be cached into permanence; call sites downgrade this
+        raise EsphomeError(
+            f"No ESPHome translation unit found in {compile_commands}; "
+            "refusing to cache unusable idedata"
+        )
+
     return {
         "cc_path": _cc_path_from_cxx(cxx_path),
         "cxx_path": cxx_path,
@@ -246,6 +375,6 @@ def idedata_from_build(compile_commands: Path) -> dict:
         "defines": defines,
         "includes": {
             "build": list(build_includes),
-            "toolchain": _get_toolchain_includes(cxx_path),
+            "toolchain": get_toolchain_includes(cxx_path),
         },
     }

esphome/build_helpers/ninja.py

@@ -0,0 +1,92 @@
+"""Platform-neutral helpers for ninja-driven native builds."""
+
+from __future__ import annotations
+
+import logging
+import os
+from pathlib import Path
+import re
+import shutil
+
+from esphome.core import EsphomeError
+from esphome.framework_helpers import strip_win_long_path_prefix, tool_version_runs
+
+_LOGGER = logging.getLogger(__name__)
+
+
+def _ninja_runs(binary: str) -> bool:
+    """Whether the ninja found on PATH actually runs (see tool_version_runs)."""
+    return tool_version_runs(
+        binary,
+        "Ignoring ninja at %s because it failed to run; "
+        "falling back to the bundled wheel",
+    )
+
+
+def find_ninja() -> Path:
+    """Locate the ninja binary: a runnable PATH hit first, else the ninja
+    PyPI wheel."""
+    if binary := shutil.which("ninja"):
+        binary = strip_win_long_path_prefix(binary)
+        if _ninja_runs(binary):
+            return Path(binary)
+    import_error: ImportError | None = None
+    try:
+        import ninja
+    except ImportError as err:
+        import_error = err
+        wheel_binary = None
+    else:
+        wheel_binary = Path(ninja.BIN_DIR) / (
+            "ninja.exe" if os.name == "nt" else "ninja"
+        )
+    if wheel_binary is None or not wheel_binary.is_file():
+        raise EsphomeError(
+            "ninja not found on PATH or in the ninja package; reinstall the "
+            "esphome Python environment"
+        ) from import_error
+    return wheel_binary
+
+
+def escape(value: Path | str) -> str:
+    """Escape a path or token for a ninja file."""
+    return str(value).replace("$", "$$").replace(":", "$:").replace(" ", "$ ")
+
+
+def quote_arg(tok: str) -> str:
+    """Quote with the CreateProcess argv rule (as ``subprocess.list2cmdline``):
+    backslash runs double only before a quote. Windows-only; ``$`` must
+    already be doubled for ninja.
+    """
+    quoted = re.sub(r'(\\*)"', lambda m: m.group(1) * 2 + '\\"', tok)
+    quoted = re.sub(r"(\\+)\Z", lambda m: m.group(1) * 2, quoted)
+    return f'"{quoted}"'
+
+
+# Force-quote any token containing a character outside the shlex.quote-style
+# safe set: ninja hands POSIX commands to /bin/sh -c, so bare (, ;, <, *, `
+# and friends would be re-parsed as shell syntax.
+_NEEDS_QUOTE = re.compile(r"[^\w@%+=:,./-]")
+
+
+def shell_token(tok: str, force: bool = False) -> str:
+    """Re-quote a lexed token for the platform shell; ``force`` always quotes.
+
+    Single quotes on POSIX (/bin/sh), the argv rule on Windows
+    (CreateProcess). ``$`` is doubled first because ninja expands it before
+    the command reaches the shell.
+    """
+    tok = tok.replace("$", "$$")  # ninja would expand a bare $ to nothing
+    if not (force or not tok or _NEEDS_QUOTE.search(tok)):
+        return tok
+    # An empty token must become '' / "" or it vanishes from the argv
+    if os.name == "nt":
+        return quote_arg(tok)
+    # shlex.quote's rule; inlined because the $-doubled token must not be
+    # re-examined for safe characters
+    return "'" + tok.replace("'", "'\"'\"'") + "'"
+
+
+def quote_path(value: Path | str) -> str:
+    """Force-quote a path for the ninja command line (shell/CreateProcess)."""
+    return shell_token(str(value), force=True)

esphome/build_helpers/size_summary.py

@@ -0,0 +1,24 @@
+"""The PlatformIO-format size bar shared by the native toolchains."""
+
+from __future__ import annotations
+
+
+def format_bar(used: int, total: int) -> str:
+    """Match PlatformIO's ``_format_availale_bytes`` (sic, pioupload.py) exactly."""
+    pct_raw = used / total if total else 0
+    blocks = 10
+    filled = min(int(round(blocks * pct_raw)), blocks)
+    progress = "=" * filled
+    return (
+        f"[{progress:<{blocks}}] {pct_raw: 6.1%} "
+        f"(used {used:d} bytes from {total:d} bytes)"
+    )
+
+
+def print_size_line(label: str, used: int, total: int) -> None:
+    """One PlatformIO-format summary line (``RAM``/``Flash``).
+
+    The label padding is part of the format: ``script/ci_memory_impact_extract.py``
+    matches these lines verbatim.
+    """
+    print(f"{label + ':':<7}{format_bar(used, total)}")

esphome/build_helpers/tools_cache.py

@@ -0,0 +1,36 @@
+"""Machine-global tools cache location shared by the native backends."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+
+def tools_cache_path(env_var: str, subdir: str) -> Path:
+    """A backend's machine-global tools directory, with an env override.
+
+    A blank/whitespace override is treated as unset: ``Path("")`` resolves
+    to the CWD, which ``clean-all`` would then delete.
+    """
+    import platformdirs
+
+    from esphome.helpers import get_str_env
+
+    if prefix := get_str_env(env_var, "").strip():
+        # resolve(): symlinked prefixes otherwise trip idf.py's
+        # venv-mismatch warning on every build
+        return Path(prefix).expanduser().resolve()
+    # appauthor=False keeps the Windows path short (no vendor segment);
+    # deep IDF trees run into MAX_PATH otherwise
+    return (
+        Path(platformdirs.user_cache_dir("esphome", appauthor=False)) / subdir
+    ).resolve()
+
+
+# (env override, cache subdir) per native backend. writer.clean_all wipes
+# every entry via tools_cache_path, so listing a cache here is the single
+# step that registers it for removal; the backends' own path getters use
+# the same named pairs so the two cannot drift.
+IDF_TOOLS_CACHE = ("ESPHOME_ESP_IDF_PREFIX", "idf")
+SDK_NRF_TOOLS_CACHE = ("ESPHOME_SDK_NRF_PREFIX", "sdk-nrf")
+ARDUINO8266_TOOLS_CACHE = ("ESPHOME_ARDUINO8266_PREFIX", "arduino8266")
+TOOLS_CACHE_SPECS = (IDF_TOOLS_CACHE, SDK_NRF_TOOLS_CACHE, ARDUINO8266_TOOLS_CACHE)

esphome/compiled_config.py

@@ -100,6 +100,21 @@ def _refresh_sidecar() -> bool:
             )
             return False
         if old is not None and old.can_apply_to_core():
+            if (
+                old.toolchain is not None
+                and CORE.toolchain is not None
+                and old.toolchain != CORE.toolchain.value
+            ):
+                # Platforms normalize toolchain-sensitive keys differently;
+                # never cache a config validated under a different toolchain
+                # than the compile's
+                _LOGGER.debug(
+                    "Not caching: config validated with toolchain %r but the "
+                    "last compile used %r",
+                    CORE.toolchain.value,
+                    old.toolchain,
+                )
+                return False
             # Compile-written; nothing to refresh.
             return True
         if CORE.build_path is not None and CORE.build_path.exists():

esphome/components/a01nyub/sensor.py

@@ -6,6 +6,7 @@ from esphome.const import (
     STATE_CLASS_MEASUREMENT,
     UNIT_METER,
 )
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@MrSuicideParrot"]
 DEPENDENCIES = ["uart"]
@@ -35,7 +36,7 @@ FINAL_VALIDATE_SCHEMA = uart.final_validate_device_schema(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await sensor.new_sensor(config)
     await cg.register_component(var, config)
     await uart.register_uart_device(var, config)

esphome/components/a02yyuw/sensor.py

@@ -6,6 +6,7 @@ from esphome.const import (
     STATE_CLASS_MEASUREMENT,
     UNIT_MILLIMETER,
 )
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@TH-Braemer"]
 DEPENDENCIES = ["uart"]
@@ -35,7 +36,7 @@ FINAL_VALIDATE_SCHEMA = uart.final_validate_device_schema(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await sensor.new_sensor(config)
     await cg.register_component(var, config)
     await uart.register_uart_device(var, config)

esphome/components/a4988/stepper.py

@@ -3,6 +3,7 @@ import esphome.codegen as cg
 from esphome.components import stepper
 import esphome.config_validation as cv
 from esphome.const import CONF_DIR_PIN, CONF_ID, CONF_SLEEP_PIN, CONF_STEP_PIN
+from esphome.types import ConfigType
 
 a4988_ns = cg.esphome_ns.namespace("a4988")
 A4988 = a4988_ns.class_("A4988", stepper.Stepper, cg.Component)
@@ -17,7 +18,7 @@ CONFIG_SCHEMA = stepper.STEPPER_SCHEMA.extend(
 ).extend(cv.COMPONENT_SCHEMA)
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await stepper.register_stepper(var, config)

esphome/components/absolute_humidity/sensor.py

@@ -9,6 +9,7 @@ from esphome.const import (
     STATE_CLASS_MEASUREMENT,
     UNIT_GRAMS_PER_CUBIC_METER,
 )
+from esphome.types import ConfigType
 
 absolute_humidity_ns = cg.esphome_ns.namespace("absolute_humidity")
 AbsoluteHumidityComponent = absolute_humidity_ns.class_(
@@ -43,7 +44,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await sensor.new_sensor(config)
     await cg.register_component(var, config)
 

esphome/components/ac_dimmer/output.py

@@ -4,6 +4,7 @@ from esphome.components import output
 import esphome.config_validation as cv
 from esphome.const import CONF_ID, CONF_METHOD, CONF_MIN_POWER
 from esphome.core import CORE
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@glmnet"]
 
@@ -48,7 +49,7 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     if CORE.is_esp32:
         from esphome.components.esp32 import include_builtin_idf_component
 

esphome/components/adalight/__init__.py

@@ -4,6 +4,9 @@ from esphome.components.light.effects import register_addressable_effect
 from esphome.components.light.types import AddressableLightEffect
 import esphome.config_validation as cv
 from esphome.const import CONF_NAME, CONF_UART_ID
+from esphome.core import ID
+from esphome.cpp_generator import MockObj
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["uart"]
 
@@ -21,7 +24,7 @@ CONFIG_SCHEMA = cv.Schema({})
     "Adalight",
     {cv.GenerateID(CONF_UART_ID): cv.use_id(uart.UARTComponent)},
 )
-async def adalight_light_effect_to_code(config, effect_id):
+async def adalight_light_effect_to_code(config: ConfigType, effect_id: ID) -> MockObj:
     effect = cg.new_Pvariable(effect_id, config[CONF_NAME])
     await uart.register_uart_device(effect, config)
     return effect

esphome/components/adc128s102/__init__.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import spi
 import esphome.config_validation as cv
 from esphome.const import CONF_ID
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["spi"]
 MULTI_CONF = True
@@ -17,7 +18,7 @@ CONFIG_SCHEMA = cv.Schema(
 ).extend(spi.spi_device_schema(cs_pin_required=True))
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await spi.register_spi_device(var, config)

esphome/components/adc128s102/sensor/__init__.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import sensor, voltage_sampler
 import esphome.config_validation as cv
 from esphome.const import CONF_CHANNEL, CONF_ID
+from esphome.types import ConfigType
 
 from .. import ADC128S102, adc128s102_ns
 
@@ -28,7 +29,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(
         config[CONF_ID],
         config[CONF_CHANNEL],

esphome/components/addressable_light/display.py

@@ -11,6 +11,7 @@ from esphome.const import (
     CONF_UPDATE_INTERVAL,
     CONF_WIDTH,
 )
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@justfalter"]
 
@@ -38,7 +39,7 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     wrapped_light = await cg.get_variable(config[CONF_ADDRESSABLE_LIGHT_ID])
     cg.add(var.set_width(config[CONF_WIDTH]))

esphome/components/ade7880/sensor.py

@@ -36,6 +36,7 @@ from esphome.const import (
     UNIT_WATT,
     UNIT_WATT_HOURS,
 )
+from esphome.cpp_generator import MockObj
 from esphome.types import ConfigType
 
 DEPENDENCIES = ["i2c"]
@@ -243,7 +244,7 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def neutral_channel(config):
+async def neutral_channel(config: ConfigType) -> MockObj:
     var = cg.new_Pvariable(config[CONF_ID])
 
     current = config[CONF_CURRENT]
@@ -257,7 +258,7 @@ async def neutral_channel(config):
     return var
 
 
-async def power_channel(config):
+async def power_channel(config: ConfigType) -> MockObj:
     var = cg.new_Pvariable(config[CONF_ID])
 
     for sensor_type in POWER_SENSOR_TYPES:
@@ -280,7 +281,7 @@ async def power_channel(config):
     return var
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await i2c.register_i2c_device(var, config)

esphome/components/ade7953_base/__init__.py

@@ -23,6 +23,8 @@ from esphome.const import (
     UNIT_VOLT_AMPS_REACTIVE,
     UNIT_WATT,
 )
+from esphome.cpp_generator import MockObj
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@angelnu"]
 
@@ -163,7 +165,7 @@ ADE7953_CONFIG_SCHEMA = cv.Schema(
 ).extend(cv.polling_component_schema("60s"))
 
 
-async def register_ade7953(var, config):
+async def register_ade7953(var: MockObj, config: ConfigType) -> None:
     await cg.register_component(var, config)
 
     if irq_pin_config := config.get(CONF_IRQ_PIN):

esphome/components/ade7953_i2c/sensor.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import ade7953_base, i2c
 import esphome.config_validation as cv
 from esphome.const import CONF_ID
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["i2c"]
 AUTO_LOAD = ["ade7953_base"]
@@ -20,7 +21,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await i2c.register_i2c_device(var, config)
     await ade7953_base.register_ade7953(var, config)

esphome/components/ade7953_spi/sensor.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import ade7953_base, spi
 import esphome.config_validation as cv
 from esphome.const import CONF_ID
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["spi"]
 AUTO_LOAD = ["ade7953_base"]
@@ -20,7 +21,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await spi.register_spi_device(var, config)
     await ade7953_base.register_ade7953(var, config)

esphome/components/ads1115/__init__.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import i2c
 import esphome.config_validation as cv
 from esphome.const import CONF_ID
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["i2c"]
 MULTI_CONF = True
@@ -24,7 +25,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await i2c.register_i2c_device(var, config)

esphome/components/ads1115/sensor/__init__.py

@@ -11,6 +11,7 @@ from esphome.const import (
     STATE_CLASS_MEASUREMENT,
     UNIT_VOLT,
 )
+from esphome.types import ConfigType
 
 from .. import CONF_ADS1115_ID, ADS1115Component, ads1115_ns
 
@@ -86,7 +87,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await sensor.register_sensor(var, config)
     await cg.register_component(var, config)

esphome/components/ads1118/__init__.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import spi
 import esphome.config_validation as cv
 from esphome.const import CONF_ID
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@solomondg1"]
 DEPENDENCIES = ["spi"]
@@ -23,7 +24,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await spi.register_spi_device(var, config)

esphome/components/ads1118/sensor/__init__.py

@@ -11,6 +11,7 @@ from esphome.const import (
     UNIT_CELSIUS,
     UNIT_VOLT,
 )
+from esphome.types import ConfigType
 
 from .. import ADS1118, CONF_ADS1118_ID, ads1118_ns
 
@@ -86,7 +87,7 @@ CONFIG_SCHEMA = cv.typed_schema(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await sensor.new_sensor(config)
     await cg.register_component(var, config)
     await cg.register_parented(var, config[CONF_ADS1118_ID])

esphome/components/aht10/sensor.py

@@ -12,6 +12,7 @@ from esphome.const import (
     UNIT_CELSIUS,
     UNIT_PERCENT,
 )
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["i2c"]
 
@@ -50,7 +51,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await i2c.register_i2c_device(var, config)

esphome/components/airthings_ble/__init__.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import ble_device_base
 import esphome.config_validation as cv
 from esphome.const import CONF_ID
+from esphome.types import ConfigType
 
 AUTO_LOAD = ["ble_device_base"]
 CODEOWNERS = ["@jeromelaban"]
@@ -21,6 +22,6 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await ble_device_base.register_ble_device(var, config)

esphome/components/airthings_wave_base/__init__.py

@@ -20,6 +20,8 @@ from esphome.const import (
     UNIT_PERCENT,
     UNIT_VOLT,
 )
+from esphome.cpp_generator import MockObj
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@ncareau", "@jeromelaban"]
 
@@ -78,7 +80,7 @@ BASE_SCHEMA = (
 )
 
 
-async def wave_base_to_code(var, config):
+async def wave_base_to_code(var: MockObj, config: ConfigType) -> None:
     await cg.register_component(var, config)
 
     await ble_client.register_ble_node(var, config)

esphome/components/airthings_wave_mini/sensor.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import airthings_wave_base
 import esphome.config_validation as cv
 from esphome.const import CONF_ID
+from esphome.types import ConfigType
 
 DEPENDENCIES = airthings_wave_base.DEPENDENCIES
 
@@ -20,6 +21,6 @@ CONFIG_SCHEMA = airthings_wave_base.BASE_SCHEMA.extend(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await airthings_wave_base.wave_base_to_code(var, config)

esphome/components/airthings_wave_plus/sensor.py

@@ -83,7 +83,7 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await airthings_wave_base.wave_base_to_code(var, config)
 

esphome/components/alpha3/sensor.py

@@ -20,6 +20,7 @@ from esphome.const import (
     UNIT_VOLT,
     UNIT_WATT,
 )
+from esphome.types import ConfigType
 
 alpha3_ns = cg.esphome_ns.namespace("alpha3")
 Alpha3 = alpha3_ns.class_("Alpha3", ble_client.BLEClientNode, cg.PollingComponent)
@@ -68,7 +69,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await ble_client.register_ble_node(var, config)

esphome/components/am2315c/sensor.py

@@ -11,6 +11,7 @@ from esphome.const import (
     UNIT_CELSIUS,
     UNIT_PERCENT,
 )
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["i2c"]
 
@@ -40,7 +41,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await i2c.register_i2c_device(var, config)

esphome/components/am2320/sensor.py

@@ -11,6 +11,7 @@ from esphome.const import (
     UNIT_CELSIUS,
     UNIT_PERCENT,
 )
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["i2c"]
 
@@ -42,7 +43,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await i2c.register_i2c_device(var, config)

esphome/components/am43/cover/__init__.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import ble_client, cover
 import esphome.config_validation as cv
 from esphome.const import CONF_PIN
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@buxtronix"]
 DEPENDENCIES = ["ble_client"]
@@ -27,7 +28,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await cover.new_cover(config)
     cg.add(var.set_pin(config[CONF_PIN]))
     cg.add(var.set_invert_position(config[CONF_INVERT_POSITION]))

esphome/components/am43/sensor/__init__.py

@@ -11,6 +11,7 @@ from esphome.const import (
     STATE_CLASS_MEASUREMENT,
     UNIT_PERCENT,
 )
+from esphome.types import ConfigType
 
 AUTO_LOAD = ["am43"]
 CODEOWNERS = ["@buxtronix"]
@@ -42,7 +43,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await ble_client.register_ble_node(var, config)

esphome/components/analog_threshold/binary_sensor.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import binary_sensor, sensor
 import esphome.config_validation as cv
 from esphome.const import CONF_SENSOR_ID, CONF_THRESHOLD
+from esphome.types import ConfigType
 
 analog_threshold_ns = cg.esphome_ns.namespace("analog_threshold")
 
@@ -32,7 +33,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await binary_sensor.new_binary_sensor(config)
     await cg.register_component(var, config)
 

esphome/components/anova/climate.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import ble_client, climate
 import esphome.config_validation as cv
 from esphome.const import CONF_UNIT_OF_MEASUREMENT
+from esphome.types import ConfigType
 
 UNITS = {
     "f": "f",
@@ -28,7 +29,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await climate.new_climate(config)
     await cg.register_component(var, config)
     await ble_client.register_ble_node(var, config)

esphome/components/apds9306/sensor.py

@@ -1,6 +1,8 @@
 # Based on this datasheet:
 # https://www.mouser.ca/datasheet/2/678/AVGO_S_A0002854364_1-2574547.pdf
 
+from typing import Any
+
 import esphome.codegen as cg
 from esphome.components import i2c, sensor
 import esphome.config_validation as cv
@@ -11,6 +13,8 @@ from esphome.const import (
     STATE_CLASS_MEASUREMENT,
     UNIT_LUX,
 )
+from esphome.cpp_generator import MockObj
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["i2c"]
 
@@ -55,7 +59,7 @@ AMBIENT_LIGHT_GAINS = {
 }
 
 
-def _validate_measurement_rate(value):
+def _validate_measurement_rate(value: Any) -> MockObj:
     value = cv.positive_time_period_milliseconds(value)
     return cv.enum(MEASUREMENT_RATES, int=True)(value.total_milliseconds)
 
@@ -85,7 +89,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await sensor.new_sensor(config)
     await cg.register_component(var, config)
     await i2c.register_i2c_device(var, config)

esphome/components/api/__init__.py

@@ -1,12 +1,21 @@
-import base64
 import logging
+import re
 from typing import Any
 
 from esphome import automation
 from esphome.automation import Condition
 import esphome.codegen as cg
 from esphome.components.logger import request_log_listener
-from esphome.config_helpers import get_logger_level
+
+# ENCRYPTION_SCHEMA and validate_encryption_key are re-exported for external
+# components and downstream consumers that import them from api
+from esphome.components.noise import (  # noqa: F401
+    ENCRYPTION_SCHEMA,
+    decode_encryption_key,
+    encryption_schema,
+    validate_encryption_key,
+)
+from esphome.config_helpers import filter_source_files_from_defines, get_logger_level
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_ACTION,
@@ -38,6 +47,10 @@ from esphome.core import CORE, ID, CoroPriority, EsphomeError, coroutine_with_pr
 from esphome.cpp_generator import MockObj, TemplateArgsType
 from esphome.types import ConfigFragmentType, ConfigType
 
+# Compat alias: downstream consumers (e.g. device-builder) referenced the
+# schema by its old private name before it moved to the noise component
+_encryption_schema = encryption_schema
+
 _LOGGER = logging.getLogger(__name__)
 
 DOMAIN = "api"
@@ -46,9 +59,15 @@ CODEOWNERS = ["@esphome/core"]
 
 
 def AUTO_LOAD(config: ConfigType) -> list[str]:
-    """Conditionally auto-load json only when capture_response is used."""
+    """Conditionally auto-load noise (encryption) and json (capture_response)."""
     base = ["socket"]
 
+    # A falsy config is a tooling probe for the maximal set (None from
+    # dependency resolution, {} from the components-graph platform probe);
+    # a validated config always carries defaults, never empty
+    if not config or CONF_ENCRYPTION in config:
+        base = base + ["noise"]
+
     # Check if any homeassistant.action/homeassistant.service has capture_response: true
     # This flag is set during config validation in _validate_response_config
     if not config or CORE.data.get(DOMAIN, {}).get(CONF_CAPTURE_RESPONSE, False):
@@ -130,20 +149,6 @@ def _register_provisioning_source(config: ConfigType) -> ConfigType:
     return config
 
 
-def validate_encryption_key(value: Any) -> str:
-    value = cv.string_strict(value)
-    try:
-        decoded = base64.b64decode(value, validate=True)
-    except ValueError as err:
-        raise cv.Invalid("Invalid key format, please check it's using base64") from err
-
-    if len(decoded) != 32:
-        raise cv.Invalid("Encryption key must be base64 and 32 bytes long")
-
-    # Return original data for roundtrip conversion
-    return value
-
-
 CONF_SUPPORTS_RESPONSE = "supports_response"
 
 # Enum values in api::enums namespace
@@ -250,18 +255,6 @@ ACTIONS_SCHEMA = automation.validate_automation(
     ),
 )
 
-ENCRYPTION_SCHEMA = cv.Schema(
-    {
-        cv.Optional(CONF_KEY): cv.sensitive(validate_encryption_key),
-    }
-)
-
-
-def _encryption_schema(config: ConfigType | None) -> ConfigType:
-    if config is None:
-        config = {}
-    return ENCRYPTION_SCHEMA(config)
-
 
 def _consume_api_sockets(config: ConfigType) -> ConfigType:
     """Register socket needs for API component."""
@@ -297,7 +290,7 @@ CONFIG_SCHEMA = cv.All(
                 CONF_SERVICES, group_of_exclusion=CONF_ACTIONS
             ): ACTIONS_SCHEMA,
             cv.Exclusive(CONF_ACTIONS, group_of_exclusion=CONF_ACTIONS): ACTIONS_SCHEMA,
-            cv.Optional(CONF_ENCRYPTION): _encryption_schema,
+            cv.Optional(CONF_ENCRYPTION): encryption_schema,
             cv.Optional(CONF_BATCH_DELAY, default="100ms"): cv.All(
                 cv.positive_time_period_milliseconds,
                 cv.Range(max=cv.TimePeriod(milliseconds=65535)),
@@ -484,7 +477,7 @@ async def to_code(config: ConfigType) -> None:
 
     if (encryption_config := config.get(CONF_ENCRYPTION, None)) is not None:
         if key := encryption_config.get(CONF_KEY):
-            decoded = base64.b64decode(key)
+            decoded = decode_encryption_key(key)
             cg.add(var.set_noise_psk(list(decoded)))
             cg.add_define("USE_API_NOISE_PSK_FROM_YAML")
         else:
@@ -498,10 +491,6 @@ async def to_code(config: ConfigType) -> None:
             # and plaintext disabled. Only a factory reset can remove it.
             cg.add_define("USE_API_PLAINTEXT")
         cg.add_define("USE_API_NOISE")
-        cg.add_library("esphome/noise-c", "0.1.21")
-        # Enable optimized memzero/memcmp in libsodium instead of volatile byte loops
-        cg.add_build_flag("-DHAVE_WEAK_SYMBOLS=1")
-        cg.add_build_flag("-DHAVE_INLINE_ASM=1")
     else:
         cg.add_define("USE_API_PLAINTEXT")
 
@@ -511,6 +500,40 @@ async def to_code(config: ConfigType) -> None:
 
 KEY_VALUE_SCHEMA = cv.Schema({cv.string: cv.templatable(cv.string_strict)})
 
+_ID_CALL_PROG = re.compile(r"\bid\s*\(")
+
+
+# Remove before 2027.3.0: untagged strings that look like lambda source keep
+# being compiled as lambdas during the deprecation window
+def _coerce_implicit_lambda(value: Any) -> Any:
+    if not isinstance(value, str):
+        return value
+    if cv.looks_like_returning_lambda(value):
+        _LOGGER.warning(
+            "[api] The 'variables' value '%s' looks like a lambda but is "
+            "missing the !lambda tag. It is compiled as a lambda for now but "
+            "will be sent as literal text from 2027.3.0. Add !lambda to keep "
+            "it evaluated; literal text belongs under 'data:'.",
+            value,
+        )
+        # cv.templatable runs returning_lambda on the coerced Lambda
+        return cv.lambda_(value)
+    if _ID_CALL_PROG.search(value):
+        # lambda source without a return: issue 5394's mistake class
+        _LOGGER.warning(
+            "[api] The 'variables' value '%s' is sent as literal text; wrap "
+            "it in !lambda 'return ...;' to evaluate it instead.",
+            value,
+        )
+    return value
+
+
+# Static strings or !lambda values. cv.templatable stays introspectable for
+# schema tooling; removing the shim leaves KEY_VALUE_SCHEMA.
+VARIABLES_SCHEMA = cv.Schema(
+    {cv.string: cv.All(_coerce_implicit_lambda, cv.templatable(cv.string_strict))}
+)
+
 
 def _validate_response_config(config: ConfigType) -> ConfigType:
     # Validate dependencies:
@@ -547,9 +570,7 @@ HOMEASSISTANT_ACTION_ACTION_SCHEMA = cv.All(
             ),
             cv.Optional(CONF_DATA, default={}): KEY_VALUE_SCHEMA,
             cv.Optional(CONF_DATA_TEMPLATE, default={}): KEY_VALUE_SCHEMA,
-            cv.Optional(CONF_VARIABLES, default={}): cv.Schema(
-                {cv.string: cv.returning_lambda}
-            ),
+            cv.Optional(CONF_VARIABLES, default={}): VARIABLES_SCHEMA,
             cv.Optional(CONF_RESPONSE_TEMPLATE): cv.templatable(cv.string),
             cv.Optional(CONF_CAPTURE_RESPONSE, default=False): cv.boolean,
             cv.Optional(CONF_ON_SUCCESS): automation.validate_automation(single=True),
@@ -610,6 +631,8 @@ async def homeassistant_service_to_code(
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
         templ = await cg.templatable(value, args, None)
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
         cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
     if on_error := config.get(CONF_ON_ERROR):
@@ -664,7 +687,7 @@ HOMEASSISTANT_EVENT_ACTION_SCHEMA = cv.Schema(
         cv.Required(CONF_EVENT): validate_homeassistant_event,
         cv.Optional(CONF_DATA, default={}): KEY_VALUE_SCHEMA,
         cv.Optional(CONF_DATA_TEMPLATE, default={}): KEY_VALUE_SCHEMA,
-        cv.Optional(CONF_VARIABLES, default={}): KEY_VALUE_SCHEMA,
+        cv.Optional(CONF_VARIABLES, default={}): VARIABLES_SCHEMA,
     }
 )
 
@@ -710,6 +733,8 @@ async def homeassistant_event_to_code(
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
         templ = await cg.templatable(value, args, None)
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
         cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
     return var
@@ -847,11 +872,20 @@ async def api_connected_to_code(
     return var
 
 
+# user_services.cpp is only needed when user defined actions exist; the
+# frame helpers are fully #ifdef'd on the protocol defines set in to_code
+# (both are set when encryption is configured without a key).
+_define_filter = filter_source_files_from_defines(
+    {
+        "user_services.cpp": "USE_API_USER_DEFINED_ACTIONS",
+        "api_frame_helper_noise.cpp": "USE_API_NOISE",
+        "api_frame_helper_plaintext.cpp": "USE_API_PLAINTEXT",
+    }
+)
+
+
 def FILTER_SOURCE_FILES() -> list[str]:
-    """Filter out api_pb2_dump.cpp when proto message dumping is not enabled,
-    user_services.cpp when no services are defined, and protocol-specific
-    implementations based on encryption configuration."""
-    files_to_filter: list[str] = []
+    files_to_filter = _define_filter()
 
     # api_pb2_dump.cpp is only needed when HAS_PROTO_MESSAGE_DUMP is defined
     # This is a particularly large file that still needs to be opened and read
@@ -862,21 +896,4 @@ def FILTER_SOURCE_FILES() -> list[str]:
     if get_logger_level() != "VERY_VERBOSE":
         files_to_filter.append("api_pb2_dump.cpp")
 
-    # user_services.cpp is only needed when services are defined
-    config = CORE.config.get(DOMAIN, {})
-    if config and not config.get(CONF_ACTIONS) and not config[CONF_CUSTOM_SERVICES]:
-        files_to_filter.append("user_services.cpp")
-
-    # Filter protocol-specific implementations based on encryption configuration
-    encryption_config = config.get(CONF_ENCRYPTION) if config else None
-
-    # If encryption is not configured at all, we only need plaintext
-    if encryption_config is None:
-        files_to_filter.append("api_frame_helper_noise.cpp")
-    # If encryption is configured with a key, we only need noise
-    elif encryption_config.get(CONF_KEY):
-        files_to_filter.append("api_frame_helper_plaintext.cpp")
-    # If encryption is configured but no key is provided, we need both
-    # (this allows a plaintext client to provide a noise key)
-
     return files_to_filter

esphome/components/api/api.proto

@@ -232,6 +232,7 @@ enum SerialProxyPortType {
 message SerialProxyInfo {
   string name = 1;                    // Human-readable port name
   SerialProxyPortType port_type = 2;  // Port type (RS232, RS485)
+  uint32 configured_line_states = 3;  // Bitmask of SerialProxyLineStateFlags this instance can drive
 }
 
 // DeviceInfoResponse max_data_length values:
@@ -1002,8 +1003,12 @@ message GetTimeResponse {
   option (no_delay) = true;
 
   fixed32 epoch_seconds = 1;
-  string timezone = 2;
-  ParsedTimezone parsed_timezone = 3;
+  // Deprecated in 2026.9.0: clients still send this string for older firmware,
+  // but new firmware only reads parsed_timezone. Clients older than Home
+  // Assistant 2026.3.0 that send only the string leave the device on its
+  // codegen-configured timezone (or UTC).
+  string timezone = 2 [deprecated = true];
+  ParsedTimezone parsed_timezone = 3 [(track_presence) = true];
 }
 
 // ==================== USER-DEFINES SERVICES ====================
@@ -1649,7 +1654,8 @@ message ListEntitiesMediaPlayerResponse {
   bool disabled_by_default = 6;
   EntityCategory entity_category = 7;
 
-  bool supports_pause = 8;
+  // Deprecated in ESPHome 2026.9.0; use feature_flags instead.
+  bool supports_pause = 8 [deprecated = true];
 
   repeated MediaPlayerSupportedFormat supported_formats = 9;
 
@@ -2622,6 +2628,22 @@ message ZWaveProxyRequest {
   bytes data = 2;
 }
 
+enum ZWaveProxyStatus {
+  ZWAVE_PROXY_STATUS_OK = 0;             // Request completed successfully
+  ZWAVE_PROXY_STATUS_IN_USE = 1;         // Denied: another client is already subscribed
+  ZWAVE_PROXY_STATUS_NOT_SUPPORTED = 2;  // Request type not supported
+}
+
+// Acknowledges a ZWaveProxyRequest (subscribe/unsubscribe). Sent since API 1.16.
+message ZWaveProxyRequestResponse {
+  option (id) = 151;
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_ZWAVE_PROXY";
+
+  ZWaveProxyRequestType type = 1;  // Which request type this responds to
+  ZWaveProxyStatus status = 2;     // Result status
+}
+
 // ==================== INFRARED ====================
 // Note: Feature and capability flag enums are defined in
 // esphome/components/infrared/infrared.h
@@ -2765,12 +2787,18 @@ message SerialProxyGetModemPinsResponse {
 
   uint32 instance = 1;          // Instance index (0-based)
   uint32 line_states = 2;       // Bitmask of SerialProxyLineStateFlags
+  SerialProxyStatus status = 3; // INVALID_ARGUMENT if the instance index is out of range (since API 1.16)
 }
 
 enum SerialProxyRequestType {
   SERIAL_PROXY_REQUEST_TYPE_SUBSCRIBE = 0;   // Subscribe to receive data from this serial proxy instance
   SERIAL_PROXY_REQUEST_TYPE_UNSUBSCRIBE = 1; // Unsubscribe from this serial proxy instance
   SERIAL_PROXY_REQUEST_TYPE_FLUSH = 2;       // Flush the serial port (block until all TX data is sent)
+  // Values below are only valid in SerialProxyRequestResponse.type, identifying which
+  // operation is being acknowledged. Sending them in SerialProxyRequest.type is an
+  // error the device answers with INVALID_ARGUMENT.
+  SERIAL_PROXY_REQUEST_TYPE_CONFIGURE = 3;      // Acknowledges a SerialProxyConfigureRequest
+  SERIAL_PROXY_REQUEST_TYPE_SET_MODEM_PINS = 4; // Acknowledges a SerialProxySetModemPinsRequest
 }
 
 enum SerialProxyStatus {
@@ -2779,6 +2807,8 @@ enum SerialProxyStatus {
   SERIAL_PROXY_STATUS_ERROR = 2;           // Driver or hardware error
   SERIAL_PROXY_STATUS_TIMEOUT = 3;         // Timed out before TX completed
   SERIAL_PROXY_STATUS_NOT_SUPPORTED = 4;   // Request type not supported by this instance
+  SERIAL_PROXY_STATUS_PORT_IN_USE = 5;     // Denied: another client holds the port
+  SERIAL_PROXY_STATUS_INVALID_ARGUMENT = 6; // Invalid instance index or parameter value
 }
 
 // Generic request message for simple serial proxy operations
@@ -2791,7 +2821,9 @@ message SerialProxyRequest {
   SerialProxyRequestType type = 2;      // Request type
 }
 
-// Response to a SerialProxyRequest (e.g. flush completion or failure)
+// Acknowledges a serial proxy operation; the type field identifies which
+// operation is being acknowledged. Flush has been acknowledged since the
+// message was introduced; all other acknowledgements are sent since API 1.16.
 message SerialProxyRequestResponse {
   option (id) = 147;
   option (source) = SOURCE_SERVER;

esphome/components/api/api_buffer.cpp

@@ -1,13 +1,20 @@
 #include "api_buffer.h"
+#include <new>
 
 namespace esphome::api {
 
-void APIBuffer::grow_(size_t n) {
-  auto new_data = make_buffer(n);
+bool APIBuffer::grow_(size_t n) {
+  // nothrow (no zero-fill) so OOM is reportable; plain new aborts instead
+  // (NEW_OOM_ABORT on ESP8266 Arduino, exception stub on ESP-IDF).
+  // RAMAllocator is no fit here: unique_ptr needs delete[]-compatible memory.
+  std::unique_ptr<uint8_t[]> new_data(new (std::nothrow) uint8_t[n]);
+  if (new_data == nullptr)
+    return false;
   if (this->size_)
     std::memcpy(new_data.get(), this->data_.get(), this->size_);
   this->data_ = std::move(new_data);
   this->capacity_ = n;
+  return true;
 }
 
 }  // namespace esphome::api

esphome/components/api/api_buffer.h

@@ -9,16 +9,6 @@
 
 namespace esphome::api {
 
-/// Helper to use make_unique_for_overwrite where available (skips zero-fill),
-/// falling back to make_unique on older GCC (ESP8266, LibreTiny).
-inline std::unique_ptr<uint8_t[]> make_buffer(size_t n) {
-#if defined(USE_ESP8266) || defined(USE_LIBRETINY)
-  return std::make_unique<uint8_t[]>(n);
-#else
-  return std::make_unique_for_overwrite<uint8_t[]>(n);
-#endif
-}
-
 /// Byte buffer that skips zero-initialization on resize().
 ///
 /// std::vector<uint8_t>::resize() zero-fills new bytes via memset. For the
@@ -36,23 +26,23 @@ inline std::unique_ptr<uint8_t[]> make_buffer(size_t n) {
 class APIBuffer {
  public:
   void clear() { this->size_ = 0; }
-  inline void reserve(size_t n) ESPHOME_ALWAYS_INLINE {
-    if (n > this->capacity_)
-      this->grow_(n);
-  }
-  inline void resize(size_t n) ESPHOME_ALWAYS_INLINE {
-    this->reserve(n);
-    this->size_ = n;  // no zero-fill
-  }
+  /// Returns false if allocation fails; the buffer is left unchanged.
+  [[nodiscard]] inline bool reserve(size_t n) ESPHOME_ALWAYS_INLINE { return n <= this->capacity_ || this->grow_(n); }
+  /// Returns false if allocation fails; the buffer is left unchanged. No zero-fill.
+  [[nodiscard]] inline bool resize(size_t n) ESPHOME_ALWAYS_INLINE { return this->reserve_and_resize(n, n); }
   /// Reserve capacity for max(reserve_size, new_size) bytes, then set size to new_size.
   /// Single grow_ check regardless of argument order.
-  inline void reserve_and_resize(size_t reserve_size, size_t new_size) ESPHOME_ALWAYS_INLINE {
-    this->reserve(std::max(reserve_size, new_size));
+  /// Returns false if allocation fails; the buffer is left unchanged.
+  [[nodiscard]] inline bool reserve_and_resize(size_t reserve_size, size_t new_size) ESPHOME_ALWAYS_INLINE {
+    if (!this->reserve(std::max(reserve_size, new_size)))
+      return false;
     this->size_ = new_size;
+    return true;
   }
   uint8_t *data() { return this->data_.get(); }
   const uint8_t *data() const { return this->data_.get(); }
   size_t size() const { return this->size_; }
+  size_t capacity() const { return this->capacity_; }
   bool empty() const { return this->size_ == 0; }
   uint8_t &operator[](size_t i) { return this->data_[i]; }
   const uint8_t &operator[](size_t i) const { return this->data_[i]; }
@@ -64,7 +54,7 @@ class APIBuffer {
   }
 
  protected:
-  void grow_(size_t n);
+  bool grow_(size_t n);
   std::unique_ptr<uint8_t[]> data_;
   size_t size_{0};
   size_t capacity_{0};

esphome/components/api/api_connection.cpp

@@ -1,6 +1,6 @@
 #include "api_connection.h"
 #ifdef USE_API
-#include "api_connection_buffer.h"  // for encode_to_buffer / get_batch_delay_ms_ inlines
+#include "api_connection_buffer.h"  // for the APIServer-dependent APIConnection inlines
 #ifdef USE_API_NOISE
 #include "api_frame_helper_noise.h"
 #endif
@@ -412,15 +412,15 @@ void APIConnection::finalize_iterator_sync_() {
 }
 
 void APIConnection::process_iterator_batch_(ComponentIterator &iterator) {
-  size_t initial_size = this->deferred_batch_.size();
-  size_t max_batch = MAX_INITIAL_PER_BATCH;
-  while (!iterator.completed() && (this->deferred_batch_.size() - initial_size) < max_batch) {
-    iterator.advance();
-  }
+  // Budget by remaining batch capacity so a pass cannot overfill the batch;
+  // stops early on a refused send and resumes next loop pass
+  size_t batch_size = this->deferred_batch_.size();
+  if (batch_size < MAX_INITIAL_BATCH_SIZE)
+    iterator.try_advance(MAX_INITIAL_BATCH_SIZE - batch_size);
 
-  // If the batch is full, process it immediately
-  // Note: iterator.advance() already calls schedule_batch_() via schedule_message_()
-  if (this->deferred_batch_.size() >= max_batch) {
+  // Flush immediately once enough is queued (not guaranteed every pass);
+  // partial batches go out via the batch timer or finalize_iterator_sync_()
+  if (this->deferred_batch_.size() >= MAX_INITIAL_BATCH_SIZE) {
     this->process_batch_();
   }
 }
@@ -1099,7 +1099,6 @@ uint16_t APIConnection::try_send_media_player_info(EntityBase *entity, APIConnec
   auto *media_player = static_cast<media_player::MediaPlayer *>(entity);
   ListEntitiesMediaPlayerResponse msg;
   auto traits = media_player->get_traits();
-  msg.supports_pause = traits.get_supports_pause();
   msg.feature_flags = traits.get_feature_flags();
   for (auto &supported_format : traits.get_supported_formats()) {
     msg.supported_formats.emplace_back();
@@ -1204,31 +1203,28 @@ void APIConnection::on_get_time_response(const GetTimeResponse &value) {
   if (homeassistant::global_homeassistant_time != nullptr) {
     homeassistant::global_homeassistant_time->set_epoch_time(value.epoch_seconds);
 #if defined(USE_HOMEASSISTANT_TIMEZONE) && defined(USE_TIME_TIMEZONE)
-    if (!value.timezone.empty()) {
-      // Check if the sender provided pre-parsed timezone data.
-      // If std_offset is non-zero or DST rules are present, the parsed data was populated.
-      // For UTC (all zeros), string parsing produces the same result, so the fallback is equivalent.
+    // Apply only if the sender provided pre-parsed timezone data (Home Assistant 2026.3.0
+    // and newer); field presence distinguishes a genuine all-zero UTC timezone from an
+    // absent field. Older clients send only the deprecated timezone string, which is no
+    // longer decoded; for them the device keeps its codegen-configured timezone.
+    if (value.has_parsed_timezone) {
       const auto &pt = value.parsed_timezone;
-      if (pt.std_offset_seconds != 0 || pt.dst_start.type != enums::DST_RULE_TYPE_NONE) {
-        time::ParsedTimezone tz{};
-        tz.std_offset_seconds = pt.std_offset_seconds;
-        tz.dst_offset_seconds = pt.dst_offset_seconds;
-        tz.dst_start.time_seconds = pt.dst_start.time_seconds;
-        tz.dst_start.day = static_cast<uint16_t>(pt.dst_start.day);
-        tz.dst_start.type = static_cast<time::DSTRuleType>(pt.dst_start.type);
-        tz.dst_start.month = static_cast<uint8_t>(pt.dst_start.month);
-        tz.dst_start.week = static_cast<uint8_t>(pt.dst_start.week);
-        tz.dst_start.day_of_week = static_cast<uint8_t>(pt.dst_start.day_of_week);
-        tz.dst_end.time_seconds = pt.dst_end.time_seconds;
-        tz.dst_end.day = static_cast<uint16_t>(pt.dst_end.day);
-        tz.dst_end.type = static_cast<time::DSTRuleType>(pt.dst_end.type);
-        tz.dst_end.month = static_cast<uint8_t>(pt.dst_end.month);
-        tz.dst_end.week = static_cast<uint8_t>(pt.dst_end.week);
-        tz.dst_end.day_of_week = static_cast<uint8_t>(pt.dst_end.day_of_week);
-        time::set_global_tz(tz);
-      } else {
-        homeassistant::global_homeassistant_time->set_timezone(value.timezone.c_str(), value.timezone.size());
-      }
+      time::ParsedTimezone tz{};
+      tz.std_offset_seconds = pt.std_offset_seconds;
+      tz.dst_offset_seconds = pt.dst_offset_seconds;
+      tz.dst_start.time_seconds = pt.dst_start.time_seconds;
+      tz.dst_start.day = static_cast<uint16_t>(pt.dst_start.day);
+      tz.dst_start.type = static_cast<time::DSTRuleType>(pt.dst_start.type);
+      tz.dst_start.month = static_cast<uint8_t>(pt.dst_start.month);
+      tz.dst_start.week = static_cast<uint8_t>(pt.dst_start.week);
+      tz.dst_start.day_of_week = static_cast<uint8_t>(pt.dst_start.day_of_week);
+      tz.dst_end.time_seconds = pt.dst_end.time_seconds;
+      tz.dst_end.day = static_cast<uint16_t>(pt.dst_end.day);
+      tz.dst_end.type = static_cast<time::DSTRuleType>(pt.dst_end.type);
+      tz.dst_end.month = static_cast<uint8_t>(pt.dst_end.month);
+      tz.dst_end.week = static_cast<uint8_t>(pt.dst_end.week);
+      tz.dst_end.day_of_week = static_cast<uint8_t>(pt.dst_end.day_of_week);
+      time::set_global_tz(tz);
     }
 #endif
   }
@@ -1384,7 +1380,12 @@ void APIConnection::on_z_wave_proxy_frame(const ZWaveProxyFrame &msg) {
 }
 
 void APIConnection::on_z_wave_proxy_request(const ZWaveProxyRequest &msg) {
-  zwave_proxy::global_zwave_proxy->zwave_proxy_request(this, msg.type);
+  ZWaveProxyRequestResponse resp{};
+  resp.type = msg.type;
+  resp.status = zwave_proxy::global_zwave_proxy->zwave_proxy_request(this, msg.type);
+  if (!this->send_message(resp)) {
+    API_LOG_MSG_DROPPED(TAG, "Z-Wave proxy response");
+  }
 }
 #endif
 
@@ -1553,15 +1554,50 @@ void APIConnection::send_infrared_rf_receive_event(const InfraredRFReceiveEvent
 #endif
 
 #ifdef USE_SERIAL_PROXY
+static enums::SerialProxyStatus serial_proxy_result_to_status(serial_proxy::SerialProxyResult result) {
+  switch (result) {
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_OK:
+      return enums::SERIAL_PROXY_STATUS_OK;
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_ASSUMED_SUCCESS:
+      return enums::SERIAL_PROXY_STATUS_ASSUMED_SUCCESS;
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_PORT_IN_USE:
+      return enums::SERIAL_PROXY_STATUS_PORT_IN_USE;
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_INVALID_ARGUMENT:
+      return enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT;
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_TIMEOUT:
+      return enums::SERIAL_PROXY_STATUS_TIMEOUT;
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_NOT_SUPPORTED:
+      return enums::SERIAL_PROXY_STATUS_NOT_SUPPORTED;
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_ERROR:
+      return enums::SERIAL_PROXY_STATUS_ERROR;
+  }
+  return enums::SERIAL_PROXY_STATUS_ERROR;  // Unreachable; all enum values handled above
+}
+
+static void send_serial_proxy_ack(APIConnection *conn, uint32_t instance, enums::SerialProxyRequestType type,
+                                  enums::SerialProxyStatus status) {
+  SerialProxyRequestResponse resp{};
+  resp.instance = instance;
+  resp.type = type;
+  resp.status = status;
+  if (!conn->send_message(resp)) {
+    API_LOG_MSG_DROPPED(TAG, "Serial proxy response");
+  }
+}
+
 void APIConnection::on_serial_proxy_configure_request(const SerialProxyConfigureRequest &msg) {
   auto &proxies = App.get_serial_proxies();
   if (msg.instance >= proxies.size()) {
     ESP_LOGW(TAG, "Serial proxy instance %" PRIu32 " out of range (max %" PRIu32 ")", msg.instance,
              static_cast<uint32_t>(proxies.size()));
+    send_serial_proxy_ack(this, msg.instance, enums::SERIAL_PROXY_REQUEST_TYPE_CONFIGURE,
+                          enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT);
     return;
   }
-  proxies[msg.instance]->configure(this, msg.baudrate, msg.flow_control, static_cast<uint8_t>(msg.parity),
-                                   msg.stop_bits, msg.data_size);
+  serial_proxy::SerialProxyResult result = proxies[msg.instance]->configure(
+      this, msg.baudrate, msg.flow_control, static_cast<uint8_t>(msg.parity), msg.stop_bits, msg.data_size);
+  send_serial_proxy_ack(this, msg.instance, enums::SERIAL_PROXY_REQUEST_TYPE_CONFIGURE,
+                        serial_proxy_result_to_status(result));
 }
 
 void APIConnection::on_serial_proxy_write_request(const SerialProxyWriteRequest &msg) {
@@ -1577,20 +1613,30 @@ void APIConnection::on_serial_proxy_set_modem_pins_request(const SerialProxySetM
   auto &proxies = App.get_serial_proxies();
   if (msg.instance >= proxies.size()) {
     ESP_LOGW(TAG, "Serial proxy instance %" PRIu32 " out of range", msg.instance);
+    send_serial_proxy_ack(this, msg.instance, enums::SERIAL_PROXY_REQUEST_TYPE_SET_MODEM_PINS,
+                          enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT);
     return;
   }
-  proxies[msg.instance]->set_modem_pins(this, msg.line_states);
+  serial_proxy::SerialProxyResult result = proxies[msg.instance]->set_modem_pins(this, msg.line_states);
+  send_serial_proxy_ack(this, msg.instance, enums::SERIAL_PROXY_REQUEST_TYPE_SET_MODEM_PINS,
+                        serial_proxy_result_to_status(result));
 }
 
 void APIConnection::on_serial_proxy_get_modem_pins_request(const SerialProxyGetModemPinsRequest &msg) {
   auto &proxies = App.get_serial_proxies();
-  if (msg.instance >= proxies.size()) {
-    ESP_LOGW(TAG, "Serial proxy instance %" PRIu32 " out of range", msg.instance);
-    return;
-  }
   SerialProxyGetModemPinsResponse resp{};
   resp.instance = msg.instance;
-  resp.line_states = proxies[msg.instance]->get_modem_pins();
+  if (msg.instance >= proxies.size()) {
+    ESP_LOGW(TAG, "Serial proxy instance %" PRIu32 " out of range", msg.instance);
+    // Pre-1.16 clients do not read the status field and would take this error
+    // for a successful "both pins deasserted" answer; let them time out as before
+    if (!this->client_supports_api_version(1, 16)) {
+      return;
+    }
+    resp.status = enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT;
+  } else {
+    resp.line_states = proxies[msg.instance]->get_modem_pins();
+  }
   if (!this->send_message(resp)) {
     API_LOG_MSG_DROPPED(TAG, "Serial proxy response");
   }
@@ -1600,40 +1646,31 @@ void APIConnection::on_serial_proxy_request(const SerialProxyRequest &msg) {
   auto &proxies = App.get_serial_proxies();
   if (msg.instance >= proxies.size()) {
     ESP_LOGW(TAG, "Serial proxy instance %" PRIu32 " out of range", msg.instance);
+    send_serial_proxy_ack(this, msg.instance, msg.type, enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT);
     return;
   }
+  auto *proxy = proxies[msg.instance];
+  enums::SerialProxyStatus status;
   switch (msg.type) {
     case enums::SERIAL_PROXY_REQUEST_TYPE_SUBSCRIBE:
     case enums::SERIAL_PROXY_REQUEST_TYPE_UNSUBSCRIBE:
-      proxies[msg.instance]->serial_proxy_request(this, msg.type);
+      status = serial_proxy_result_to_status(proxy->serial_proxy_request(this, msg.type));
       break;
-    case enums::SERIAL_PROXY_REQUEST_TYPE_FLUSH: {
-      SerialProxyRequestResponse resp{};
-      resp.instance = msg.instance;
-      resp.type = enums::SERIAL_PROXY_REQUEST_TYPE_FLUSH;
-      switch (proxies[msg.instance]->flush_port()) {
-        case uart::UARTFlushResult::UART_FLUSH_RESULT_SUCCESS:
-          resp.status = enums::SERIAL_PROXY_STATUS_OK;
-          break;
-        case uart::UARTFlushResult::UART_FLUSH_RESULT_ASSUMED_SUCCESS:
-          resp.status = enums::SERIAL_PROXY_STATUS_ASSUMED_SUCCESS;
-          break;
-        case uart::UARTFlushResult::UART_FLUSH_RESULT_TIMEOUT:
-          resp.status = enums::SERIAL_PROXY_STATUS_TIMEOUT;
-          break;
-        case uart::UARTFlushResult::UART_FLUSH_RESULT_FAILED:
-          resp.status = enums::SERIAL_PROXY_STATUS_ERROR;
-          break;
-      }
-      if (!this->send_message(resp)) {
-        API_LOG_MSG_DROPPED(TAG, "Serial proxy response");
-      }
+    case enums::SERIAL_PROXY_REQUEST_TYPE_FLUSH:
+      status = serial_proxy_result_to_status(proxy->flush_port(this));
+      break;
+    case enums::SERIAL_PROXY_REQUEST_TYPE_CONFIGURE:
+    case enums::SERIAL_PROXY_REQUEST_TYPE_SET_MODEM_PINS:
+      // Response-only discriminators; never valid in a request
+      ESP_LOGW(TAG, "Response-only serial proxy request type: %" PRIu32, static_cast<uint32_t>(msg.type));
+      status = enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT;
       break;
-    }
     default:
       ESP_LOGW(TAG, "Unknown serial proxy request type: %" PRIu32, static_cast<uint32_t>(msg.type));
+      status = enums::SERIAL_PROXY_STATUS_NOT_SUPPORTED;
       break;
   }
+  send_serial_proxy_ack(this, msg.instance, msg.type, status);
 }
 
 void APIConnection::send_serial_proxy_data(const SerialProxyDataReceived &msg) {
@@ -1752,15 +1789,17 @@ void APIConnection::complete_authentication_() {
 bool APIConnection::send_hello_response_(const HelloRequest &msg) {
   // Copy client name with truncation if needed (set_client_name handles truncation)
   this->helper_->set_client_name(msg.client_info.c_str(), msg.client_info.size());
-  this->client_api_version_major_ = msg.api_version_major;
-  this->client_api_version_minor_ = msg.api_version_minor;
+  this->client_api_version_major_ =
+      static_cast<uint8_t>(std::min<uint32_t>(msg.api_version_major, std::numeric_limits<uint8_t>::max()));
+  this->client_api_version_minor_ =
+      static_cast<uint8_t>(std::min<uint32_t>(msg.api_version_minor, std::numeric_limits<uint8_t>::max()));
   char peername[socket::SOCKADDR_STR_LEN];
-  ESP_LOGV(TAG, "Hello from client: '%s' | %s | API Version %" PRIu16 ".%" PRIu16, this->helper_->get_client_name(),
+  ESP_LOGV(TAG, "Hello from client: '%s' | %s | API Version %u.%u", this->helper_->get_client_name(),
            this->helper_->get_peername_to(peername), this->client_api_version_major_, this->client_api_version_minor_);
 
   HelloResponse resp;
   resp.api_version_major = 1;
-  resp.api_version_minor = 15;
+  resp.api_version_minor = 16;
   // Send only the version string - the client only logs this for debugging and doesn't use it otherwise
   resp.server_info = ESPHOME_VERSION_REF;
   resp.name = StringRef(App.get_name());
@@ -1894,6 +1933,7 @@ bool APIConnection::send_device_info_response_() {
     auto &info = resp.serial_proxies[serial_proxy_index++];
     info.name = StringRef(proxy->get_name());
     info.port_type = proxy->get_port_type();
+    info.configured_line_states = proxy->get_configured_modem_pins();
   }
 #endif
 #ifdef USE_API_NOISE
@@ -1954,6 +1994,7 @@ bool APIConnection::send_device_capabilities_response_() {
     auto &info = resp.serial_proxies[serial_proxy_index++];
     info.name = StringRef(proxy->get_name());
     info.port_type = proxy->get_port_type();
+    info.configured_line_states = proxy->get_configured_modem_pins();
   }
 #endif
   return this->send_message(resp);
@@ -2130,7 +2171,7 @@ bool APIConnection::send_noise_encryption_set_key_response_(const NoiseEncryptio
   }
 #endif
 
-  psk_t psk{};
+  noise::psk_t psk{};
   if (msg.key_len == 0) {
     if (this->parent_->clear_noise_psk(true)) {
       resp.success = true;
@@ -2139,7 +2180,7 @@ bool APIConnection::send_noise_encryption_set_key_response_(const NoiseEncryptio
     }
   } else if (base64_decode(msg.key, msg.key_len, psk.data(), psk.size()) != psk.size()) {
     ESP_LOGW(TAG, "Invalid encryption key length");
-  } else if (APINoiseContext::is_all_zeros(psk)) {
+  } else if (noise::NoiseContext::is_all_zeros(psk)) {
     // Accepting the reserved provisioning PSK would report success without
     // enabling encryption (or silently clear an existing key)
     ESP_LOGW(TAG, "Rejecting all-zero encryption key");
@@ -2184,7 +2225,7 @@ bool APIConnection::try_to_clear_buffer_slow_(bool log_out_of_space) {
   }
   return false;
 }
-bool APIConnection::send_message_(uint32_t payload_size, uint8_t message_type, MessageEncodeFn encode_fn,
+bool APIConnection::send_message_(uint32_t payload_size, uint16_t message_type, MessageEncodeFn encode_fn,
                                   const void *msg) {
 #ifdef HAS_PROTO_MESSAGE_DUMP
   // Skip dump for log messages (recursive logging risk) and camera frames (high-frequency noise)
@@ -2198,10 +2239,17 @@ bool APIConnection::send_message_(uint32_t payload_size, uint8_t message_type, M
     this->log_send_message_(proto_msg->message_name(), proto_msg->dump_to(dump_buf));
   }
 #endif
+  if (!this->prepare_first_message_buffer(payload_size)) [[unlikely]] {
+    this->fatal_out_of_memory_();
+    return false;
+  }
   auto &shared_buf = this->parent_->get_shared_buffer_ref();
-  this->prepare_first_message_buffer(shared_buf, payload_size);
   size_t write_start = shared_buf.size();
-  shared_buf.resize(write_start + payload_size);
+#ifdef ESPHOME_DEBUG_API
+  assert(shared_buf.capacity() >= write_start + payload_size);
+#endif
+  // Capacity reserved above, cannot fail
+  (void) shared_buf.resize(write_start + payload_size);
   ProtoWriteBuffer buffer{&shared_buf, write_start};
   encode_fn(msg, buffer PROTO_ENCODE_DEBUG_INIT(&shared_buf));
   return this->send_buffer(ProtoWriteBuffer{&shared_buf}, message_type);
@@ -2213,7 +2261,7 @@ uint16_t APIConnection::encode_to_buffer_slow(uint32_t calculated_size, MessageE
                                               APIConnection *conn, uint32_t remaining_size) {
   return encode_to_buffer(calculated_size, encode_fn, msg, conn, remaining_size);
 }
-bool APIConnection::send_buffer(ProtoWriteBuffer buffer, uint8_t message_type) {
+bool APIConnection::send_buffer(ProtoWriteBuffer buffer, uint16_t message_type) {
   const bool is_log_message = (message_type == SubscribeLogsResponse::MESSAGE_TYPE);
 
   if (!this->try_to_clear_buffer(!is_log_message)) {
@@ -2237,30 +2285,42 @@ void APIConnection::on_no_setup_connection() {
   this->on_fatal_error();
   this->log_client_(ESPHOME_LOG_LEVEL_DEBUG, LOG_STR("no connection setup"));
 }
+void APIConnection::fatal_out_of_memory_() {
+  this->fatal_error_with_log_(LOG_STR("Out of memory"), APIError::OUT_OF_MEMORY);
+}
 void APIConnection::on_fatal_error() {
   // Don't close socket here - keep it open so getpeername() works for logging
   // Socket will be closed when client is removed from the list in APIServer::loop()
   this->flags_.remove = true;
 }
 
-bool APIConnection::schedule_message_front_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size) {
+bool APIConnection::schedule_message_front_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size) {
   this->deferred_batch_.add_item_front(entity, message_type, estimated_size);
   return this->schedule_batch_();
 }
 
-bool APIConnection::send_message_smart_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
+bool APIConnection::send_message_smart_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size,
                                         uint8_t aux_data_index) {
   if (this->should_send_immediately_(message_type) && this->helper_->can_write_without_blocking()) {
-    auto &shared_buf = this->parent_->get_shared_buffer_ref();
-    this->prepare_first_message_buffer(shared_buf, estimated_size);
+    // No local for the shared buffer here: keeping it live across
+    // dispatch_message_ costs a register and spills message_type into the
+    // batching path's dedup loop (measured on x86 GCC -Os)
+    if (!this->prepare_first_message_buffer(estimated_size)) [[unlikely]] {
+      this->fatal_out_of_memory_();
+      return false;
+    }
     DeferredBatch::BatchItem item{entity, message_type, estimated_size, aux_data_index};
     if (this->dispatch_message_(item, MAX_BATCH_PACKET_SIZE, true) &&
-        this->send_buffer(ProtoWriteBuffer{&shared_buf}, message_type)) {
+        this->send_buffer(ProtoWriteBuffer{&this->parent_->get_shared_buffer_ref()}, message_type)) {
 #ifdef HAS_PROTO_MESSAGE_DUMP
       this->log_batch_item_(item);
 #endif
       return true;
     }
+    // An OOM during the immediate attempt marks the connection for removal;
+    // don't queue more work (schedule_message_'s push_back may allocate again)
+    if (this->flags_.remove) [[unlikely]]
+      return false;
   }
   return this->schedule_message_(entity, message_type, estimated_size, aux_data_index);
 }
@@ -2310,7 +2370,11 @@ void APIConnection::process_batch_() {
     total_estimated_size = MAX_BATCH_PACKET_SIZE;
   }
 
-  this->prepare_first_message_buffer(shared_buf, header_padding, total_estimated_size);
+  if (!this->prepare_first_message_buffer(header_padding, total_estimated_size)) [[unlikely]] {
+    this->fatal_out_of_memory_();
+    this->clear_batch_();
+    return;
+  }
 
   // Fast path for single message - buffer already allocated above
   if (num_items == 1) {
@@ -2325,8 +2389,10 @@ void APIConnection::process_batch_() {
 #endif
       this->clear_batch_();
     } else if (payload_size == 0) {
-      // Message too large to fit in available space
-      ESP_LOGW(TAG, "Message too large to send: type=%u", item.message_type);
+      // payload_size == 0 with remove set means encoding hit OOM and the
+      // connection is being dropped; warn only for a genuinely oversized message
+      if (!this->flags_.remove)
+        ESP_LOGW(TAG, "Message too large to send: type=%u", item.message_type);
       this->clear_batch_();
     }
     return;
@@ -2389,8 +2455,10 @@ void APIConnection::process_batch_multi_(APIBuffer &shared_buf, size_t num_items
 
   if (items_processed > 0) {
     // Add footer space for the last message (for Noise protocol MAC)
-    if (footer_size > 0) {
-      shared_buf.resize(shared_buf.size() + footer_size);
+    if (footer_size > 0 && !shared_buf.resize(shared_buf.size() + footer_size)) [[unlikely]] {
+      this->fatal_out_of_memory_();
+      this->clear_batch_();
+      return;
     }
 
     // Send all collected messages

esphome/components/api/api_connection.h

@@ -53,11 +53,11 @@ void log_dropped_message(const char *tag, int line, const LogString *what);
 
 // Keepalive timeout in milliseconds
 static constexpr uint32_t KEEPALIVE_TIMEOUT_MS = 60000;
-// Maximum number of entities to process in a single batch during initial state/info sending
-static constexpr size_t MAX_INITIAL_PER_BATCH = 34;
+// Deferred batch size cap during initial state/info sync
+static constexpr size_t MAX_INITIAL_BATCH_SIZE = 34;
 // Verify MAX_MESSAGES_PER_BATCH (defined in api_frame_helper.h) can hold the initial batch
-static_assert(MAX_MESSAGES_PER_BATCH >= MAX_INITIAL_PER_BATCH,
-              "MAX_MESSAGES_PER_BATCH must be >= MAX_INITIAL_PER_BATCH");
+static_assert(MAX_MESSAGES_PER_BATCH >= MAX_INITIAL_BATCH_SIZE,
+              "MAX_MESSAGES_PER_BATCH must be >= MAX_INITIAL_BATCH_SIZE");
 
 #ifdef USE_BENCHMARK
 class APIConnection;
@@ -326,8 +326,10 @@ class APIConnection final : public APIServerConnectionBase {
   bool is_marked_for_removal() const { return this->flags_.remove; }
   uint8_t get_log_subscription_level() const { return this->flags_.log_subscription; }
 
-  // Get client API version for feature detection
-  bool client_supports_api_version(uint16_t major, uint16_t minor) const {
+  // Get client API version for feature detection.
+  // Stored versions saturate at 255 (see send_hello_response_), so requesting
+  // a minimum above that can never match.
+  bool client_supports_api_version(uint8_t major, uint8_t minor) const {
     return this->client_api_version_major_ > major ||
            (this->client_api_version_major_ == major && this->client_api_version_minor_ >= minor);
   }
@@ -350,22 +352,13 @@ class APIConnection final : public APIServerConnectionBase {
     }
   }
 
-  void prepare_first_message_buffer(APIBuffer &shared_buf, size_t header_padding, size_t total_size) {
-    shared_buf.clear();
-    // Reserve space for header padding + message + footer
-    // - Header padding: space for protocol headers (7 bytes for Noise, 6 for Plaintext)
-    // - Footer: space for MAC (16 bytes for Noise, 0 for Plaintext)
-    // Reserve full size but only set initial size to header padding
-    // so message encoding starts at the correct position
-    shared_buf.reserve_and_resize(total_size, header_padding);
-  }
+  /// Clear the shared write buffer and reserve space for the first message.
+  /// Returns false if the allocation fails (out of memory).
+  /// Defined in api_connection_buffer.h (needs APIServer complete).
+  [[nodiscard]] bool prepare_first_message_buffer(size_t header_padding, size_t total_size);
 
   // Convenience overload - computes frame overhead internally
-  void prepare_first_message_buffer(APIBuffer &shared_buf, size_t payload_size) {
-    const uint8_t header_padding = this->helper_->frame_header_padding();
-    const uint8_t footer_size = this->helper_->frame_footer_size();
-    this->prepare_first_message_buffer(shared_buf, header_padding, payload_size + header_padding + footer_size);
-  }
+  [[nodiscard]] bool prepare_first_message_buffer(size_t payload_size);
 
   bool try_to_clear_buffer(bool log_out_of_space) {
     if (this->flags_.remove)
@@ -374,7 +367,7 @@ class APIConnection final : public APIServerConnectionBase {
       return true;
     return this->try_to_clear_buffer_slow_(log_out_of_space);
   }
-  bool send_buffer(ProtoWriteBuffer buffer, uint8_t message_type);
+  bool send_buffer(ProtoWriteBuffer buffer, uint16_t message_type);
 
   const char *get_name() const { return this->helper_->get_client_name(); }
   /// Get peer name (IP address) into caller-provided buffer, returns buf for convenience
@@ -423,7 +416,7 @@ class APIConnection final : public APIServerConnectionBase {
   }
 
   // Non-template buffer management for send_message
-  bool send_message_(uint32_t payload_size, uint8_t message_type, MessageEncodeFn encode_fn, const void *msg);
+  bool send_message_(uint32_t payload_size, uint16_t message_type, MessageEncodeFn encode_fn, const void *msg);
 
   // Core batch encoding logic. ALWAYS_INLINE so encode_fn devirtualizes at hot call sites.
   // Defined in api_connection_buffer.h (needs APIServer complete).
@@ -664,10 +657,9 @@ class APIConnection final : public APIServerConnectionBase {
 
     struct BatchItem {
       EntityBase *entity;                       // 4 bytes - Entity pointer
-      uint8_t message_type;                     // 1 byte - Message type for protocol and dispatch
+      uint16_t message_type;                    // 2 bytes - Message type for protocol and dispatch
       uint8_t estimated_size;                   // 1 byte - Estimated message size (max 255 bytes)
       uint8_t aux_data_index{AUX_DATA_UNUSED};  // 1 byte - For events: index into entity's event_types
-      // 1 byte padding
     };
 
     std::vector<BatchItem> items;
@@ -677,7 +669,7 @@ class APIConnection final : public APIServerConnectionBase {
     // connections that do, buffers are released after initial sync anyway
 
     // Add item to the batch (with deduplication)
-    void add_item(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
+    void add_item(EntityBase *entity, uint16_t message_type, uint8_t estimated_size,
                   uint8_t aux_data_index = AUX_DATA_UNUSED) {
       // Dedup: O(n) scan but optimized for RAM over performance
       // Skip deduplication for events - they are edge-triggered, every occurrence matters
@@ -693,7 +685,7 @@ class APIConnection final : public APIServerConnectionBase {
       this->items.push_back({entity, message_type, estimated_size, aux_data_index});
     }
     // Add item to the front of the batch (for high priority messages like ping)
-    void add_item_front(EntityBase *entity, uint8_t message_type, uint8_t estimated_size) {
+    void add_item_front(EntityBase *entity, uint16_t message_type, uint8_t estimated_size) {
       // Swap to front avoids expensive vector::insert which shifts all elements
       this->items.push_back({entity, message_type, estimated_size, AUX_DATA_UNUSED});
       if (this->items.size() > 1) {
@@ -758,13 +750,15 @@ class APIConnection final : public APIServerConnectionBase {
 #endif
   } flags_{};  // 2 bytes total
 
-  // 2-byte types immediately after flags_ (no padding between them)
-  uint16_t client_api_version_major_{0};
-  uint16_t client_api_version_minor_{0};
+  // 2-byte type immediately after flags_ (no padding between them)
+  uint16_t batch_message_type_{0};  // Current message type during batch encoding
   // 1-byte types to fill remaining space before next 4-byte boundary
+  // Client API versions are clamped to 255 on receive (see send_hello_response_)
+  uint8_t client_api_version_major_{0};
+  uint8_t client_api_version_minor_{0};
   ActiveIterator active_iterator_{ActiveIterator::NONE};
-  uint8_t batch_message_type_{0};  // Current message type during batch encoding
-  // Total: 2 (flags) + 2 + 2 + 1 + 1 = 8 bytes, aligned to 4-byte boundary
+  // Total: 2 (flags) + 2 + 1 + 1 + 1 + 1 (batch_header_size_ below) = 8 bytes,
+  // aligned to 4-byte boundary
 
   // Actual header size used by encode_to_buffer for the current message.
   // Read by process_batch_multi_ to pass into MessageInfo.
@@ -813,7 +807,7 @@ class APIConnection final : public APIServerConnectionBase {
   // 2. It's an EventResponse (events are edge-triggered - every occurrence matters)
   // 3. OR: User has opted into immediate sending (should_try_send_immediately = true
   //    AND batch_delay = 0)
-  inline bool should_send_immediately_(uint8_t message_type) const {
+  inline bool should_send_immediately_(uint16_t message_type) const {
     return (
 #ifdef USE_UPDATE
         message_type == UpdateStateResponse::MESSAGE_TYPE ||
@@ -827,11 +821,11 @@ class APIConnection final : public APIServerConnectionBase {
   // Helper method to send a message either immediately or via batching
   // Tries immediate send if should_send_immediately_() returns true and buffer has space
   // Falls back to batching if immediate send fails or isn't applicable
-  bool send_message_smart_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
+  bool send_message_smart_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size,
                            uint8_t aux_data_index = DeferredBatch::AUX_DATA_UNUSED);
 
   // Helper function to schedule a deferred message with known message type
-  bool schedule_message_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
+  bool schedule_message_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size,
                          uint8_t aux_data_index = DeferredBatch::AUX_DATA_UNUSED) {
     this->deferred_batch_.add_item(entity, message_type, estimated_size, aux_data_index);
     return this->schedule_batch_();
@@ -839,7 +833,7 @@ class APIConnection final : public APIServerConnectionBase {
 
   // Helper function to schedule a high priority message at the front of the batch
   // Out-of-line: callers (on_shutdown, check_keepalive_) are cold paths
-  bool schedule_message_front_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size);
+  bool schedule_message_front_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size);
 
   // Helper function to log client messages with name and peername
   void log_client_(int level, const LogString *message);
@@ -850,6 +844,9 @@ class APIConnection final : public APIServerConnectionBase {
     this->on_fatal_error();
     this->log_warning_(message, err);
   }
+  // Shared cold path for buffer allocation failures — noinline keeps the
+  // OOM handling out of the hot send paths
+  void __attribute__((noinline)) fatal_out_of_memory_();
 };
 
 }  // namespace esphome::api

esphome/components/api/api_connection_buffer.h

@@ -3,8 +3,8 @@
 #include "esphome/core/defines.h"
 #ifdef USE_API
 
-// Inline APIConnection methods that need APIServer complete. Include this
-// instead of api_connection.h when calling encode_to_buffer or get_batch_delay_ms_.
+// Inline APIConnection members that need APIServer complete. Include this
+// instead of api_connection.h when calling them.
 
 #include "api_connection.h"
 #include "api_server.h"
@@ -41,7 +41,10 @@ inline uint16_t ESPHOME_ALWAYS_INLINE APIConnection::encode_to_buffer(uint32_t c
     return 0;
 
   auto &shared_buf = conn->parent_->get_shared_buffer_ref();
-  shared_buf.resize(shared_buf.size() + to_add);
+  if (!shared_buf.resize(shared_buf.size() + to_add)) [[unlikely]] {
+    conn->fatal_out_of_memory_();
+    return 0;
+  }
   ProtoWriteBuffer buffer{&shared_buf, shared_buf.size() - calculated_size};
   encode_fn(msg, buffer PROTO_ENCODE_DEBUG_INIT(&shared_buf));
 
@@ -50,5 +53,22 @@ inline uint16_t ESPHOME_ALWAYS_INLINE APIConnection::encode_to_buffer(uint32_t c
 
 inline uint32_t APIConnection::get_batch_delay_ms_() const { return this->parent_->get_batch_delay(); }
 
+inline bool APIConnection::prepare_first_message_buffer(size_t header_padding, size_t total_size) {
+  auto &shared_buf = this->parent_->get_shared_buffer_ref();
+  shared_buf.clear();
+  // Reserve space for header padding + message + footer
+  // - Header padding: space for protocol headers (7 bytes for Noise, 6 for Plaintext)
+  // - Footer: space for MAC (16 bytes for Noise, 0 for Plaintext)
+  // Reserve full size but only set initial size to header padding
+  // so message encoding starts at the correct position
+  return shared_buf.reserve_and_resize(total_size, header_padding);
+}
+
+inline bool APIConnection::prepare_first_message_buffer(size_t payload_size) {
+  const uint8_t header_padding = this->helper_->frame_header_padding();
+  const uint8_t footer_size = this->helper_->frame_footer_size();
+  return this->prepare_first_message_buffer(header_padding, payload_size + header_padding + footer_size);
+}
+
 }  // namespace esphome::api
 #endif

esphome/components/api/api_frame_helper.cpp

@@ -172,7 +172,7 @@ APIError APIFrameHelper::write_raw_iov_(const struct iovec *iov, int iovcnt, uin
 
   // Queue unsent data into overflow buffer
   if (!this->overflow_buf_.enqueue_iov(iov, iovcnt, total_write_len, static_cast<uint16_t>(sent))) {
-    HELPER_LOG("Overflow buffer full, dropping connection");
+    HELPER_LOG("Overflow buffer full or out of memory, dropping connection");
     this->state_ = State::FAILED;
     return APIError::SOCKET_WRITE_FAILED;
   }

esphome/components/api/api_frame_helper.h

@@ -36,7 +36,7 @@ static constexpr uint16_t MAX_MESSAGE_SIZE = 32768;  // 32 KiB for ESP32 and oth
 static constexpr uint16_t RX_BUF_NULL_TERMINATOR = 1;
 
 // Maximum number of messages to batch in a single write operation
-// Must be >= MAX_INITIAL_PER_BATCH in api_connection.h (enforced by static_assert there)
+// Must be >= MAX_INITIAL_BATCH_SIZE in api_connection.h (enforced by static_assert there)
 static constexpr size_t MAX_MESSAGES_PER_BATCH = 34;
 
 // Max client name length (e.g., "Home Assistant 2026.1.0.dev0" = 28 chars)
@@ -49,16 +49,16 @@ struct ReadPacketBuffer {
 };
 
 // Packed message info structure to minimize memory usage
-// Note: message_type is uint8_t — all current protobuf message types fit in 8 bits.
-// The noise wire format encodes types as 16-bit, but the high byte is always 0.
-// If message types ever exceed 255, this and encrypt_noise_message_ must be updated.
+// message_type matches the wire formats: noise carries a fixed 16-bit type
+// field, plaintext a type varint. The proto codegen caps message IDs at 16383
+// so the plaintext type varint fits the 2 bytes budgeted in HEADER_PADDING.
 struct MessageInfo {
   uint16_t offset;        // Offset in buffer where message starts
   uint16_t payload_size;  // Size of the message payload
-  uint8_t message_type;   // Message type (0-255)
+  uint16_t message_type;  // Message type (0-16383)
   uint8_t header_size;    // Actual header size used (avoids recomputation in write path)
 
-  MessageInfo(uint8_t type, uint16_t off, uint16_t size, uint8_t hdr)
+  MessageInfo(uint16_t type, uint16_t off, uint16_t size, uint8_t hdr)
       : offset(off), payload_size(size), message_type(type), header_size(hdr) {}
 };
 
@@ -173,7 +173,7 @@ class APIFrameHelper {
   }
   // Write a single protobuf message - the hot path (87-100% of all writes).
   // Caller must ensure state is DATA before calling.
-  virtual APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) = 0;
+  virtual APIError write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) = 0;
   // Write multiple protobuf messages in a single batched operation.
   // Caller must ensure state is DATA and messages is not empty.
   // messages contains (message_type, offset, length) for each message in the buffer.
@@ -187,15 +187,15 @@ class APIFrameHelper {
   // Distinguishes protocols via frame_footer_size_ (noise always has a non-zero MAC
   // footer, plaintext has footer=0). If a protocol with a plaintext footer is ever
   // added, this should become a virtual method.
-  uint8_t frame_header_size(uint16_t payload_size, uint8_t message_type) const {
+  uint8_t frame_header_size(uint16_t payload_size, uint16_t message_type) const {
 #if defined(USE_API_NOISE) && defined(USE_API_PLAINTEXT)
     return this->frame_footer_size_
                ? this->frame_header_padding_
-               : static_cast<uint8_t>(1 + ProtoSize::varint16(payload_size) + ProtoSize::varint8(message_type));
+               : static_cast<uint8_t>(1 + ProtoSize::varint16(payload_size) + ProtoSize::varint16(message_type));
 #elif defined(USE_API_NOISE)
     return this->frame_header_padding_;
 #else  // USE_API_PLAINTEXT only
-    return static_cast<uint8_t>(1 + ProtoSize::varint16(payload_size) + ProtoSize::varint8(message_type));
+    return static_cast<uint8_t>(1 + ProtoSize::varint16(payload_size) + ProtoSize::varint16(message_type));
 #endif
   }
   // Get the frame footer size required by this protocol

esphome/components/api/api_frame_helper_noise.cpp

@@ -2,9 +2,9 @@
 #ifdef USE_API
 #ifdef USE_API_NOISE
 #include "api_connection.h"  // For ClientInfo struct
+#include "esphome/components/noise/noise.h"
 #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"
 #include "proto.h"
@@ -17,6 +17,14 @@
 
 namespace esphome::api {
 
+using noise::noise_err_to_logstr;
+
+// api_frame_helper.h keeps its own MAX_HANDSHAKE_SIZE because that header is
+// also compiled in plaintext-only builds without the noise component; keep
+// the two definitions from drifting apart.
+static_assert(MAX_HANDSHAKE_SIZE == noise::MAX_HANDSHAKE_SIZE,
+              "api and noise component handshake size limits must match");
+
 static const char *const TAG = "api.noise";
 #ifdef USE_ESP8266
 static constexpr char PROLOGUE_INIT[] PROGMEM = "NoiseAPIInit";
@@ -51,45 +59,6 @@ static constexpr size_t API_MAX_LOG_BYTES = 168;
 #define LOG_PACKET_RECEIVED(buffer) ((void) 0)
 #endif
 
-/// Convert a noise error code to a readable error
-const LogString *noise_err_to_logstr(int err) {
-  if (err == NOISE_ERROR_NO_MEMORY)
-    return LOG_STR("NO_MEMORY");
-  if (err == NOISE_ERROR_UNKNOWN_ID)
-    return LOG_STR("UNKNOWN_ID");
-  if (err == NOISE_ERROR_UNKNOWN_NAME)
-    return LOG_STR("UNKNOWN_NAME");
-  if (err == NOISE_ERROR_MAC_FAILURE)
-    return LOG_STR("MAC_FAILURE");
-  if (err == NOISE_ERROR_NOT_APPLICABLE)
-    return LOG_STR("NOT_APPLICABLE");
-  if (err == NOISE_ERROR_SYSTEM)
-    return LOG_STR("SYSTEM");
-  if (err == NOISE_ERROR_REMOTE_KEY_REQUIRED)
-    return LOG_STR("REMOTE_KEY_REQUIRED");
-  if (err == NOISE_ERROR_LOCAL_KEY_REQUIRED)
-    return LOG_STR("LOCAL_KEY_REQUIRED");
-  if (err == NOISE_ERROR_PSK_REQUIRED)
-    return LOG_STR("PSK_REQUIRED");
-  if (err == NOISE_ERROR_INVALID_LENGTH)
-    return LOG_STR("INVALID_LENGTH");
-  if (err == NOISE_ERROR_INVALID_PARAM)
-    return LOG_STR("INVALID_PARAM");
-  if (err == NOISE_ERROR_INVALID_STATE)
-    return LOG_STR("INVALID_STATE");
-  if (err == NOISE_ERROR_INVALID_NONCE)
-    return LOG_STR("INVALID_NONCE");
-  if (err == NOISE_ERROR_INVALID_PRIVATE_KEY)
-    return LOG_STR("INVALID_PRIVATE_KEY");
-  if (err == NOISE_ERROR_INVALID_PUBLIC_KEY)
-    return LOG_STR("INVALID_PUBLIC_KEY");
-  if (err == NOISE_ERROR_INVALID_FORMAT)
-    return LOG_STR("INVALID_FORMAT");
-  if (err == NOISE_ERROR_INVALID_SIGNATURE)
-    return LOG_STR("INVALID_SIGNATURE");
-  return LOG_STR("UNKNOWN");
-}
-
 /// Initialize the frame helper, returns OK if successful.
 APIError APINoiseFrameHelper::init() {
   APIError err = init_common_();
@@ -99,7 +68,10 @@ APIError APINoiseFrameHelper::init() {
 
   // init prologue
   size_t old_size = prologue_.size();
-  prologue_.resize(old_size + PROLOGUE_INIT_LEN);
+  if (!prologue_.resize(old_size + PROLOGUE_INIT_LEN)) [[unlikely]] {
+    state_ = State::FAILED;
+    return APIError::OUT_OF_MEMORY;
+  }
 #ifdef USE_ESP8266
   memcpy_P(prologue_.data() + old_size, PROLOGUE_INIT, PROLOGUE_INIT_LEN);
 #else
@@ -194,9 +166,9 @@ APIError APINoiseFrameHelper::loop() {
  */
 APIError APINoiseFrameHelper::try_read_frame_() {
   // read header
-  if (rx_header_buf_len_ < 3) {
+  if (rx_header_buf_len_ < noise::FRAME_HEADER_SIZE) {
     // no header information yet
-    uint8_t to_read = 3 - rx_header_buf_len_;
+    uint8_t to_read = static_cast<uint8_t>(noise::FRAME_HEADER_SIZE) - rx_header_buf_len_;
     ssize_t received = this->socket_->read(&rx_header_buf_[rx_header_buf_len_], to_read);
     APIError err = handle_socket_read_result_(received);
     if (err != APIError::OK) {
@@ -208,7 +180,7 @@ APIError APINoiseFrameHelper::try_read_frame_() {
       return APIError::WOULD_BLOCK;
     }
 
-    if (rx_header_buf_[0] != 0x01) {
+    if (rx_header_buf_[0] != noise::FRAME_INDICATOR) {
       state_ = State::FAILED;
       HELPER_LOG("Bad indicator byte %u", rx_header_buf_[0]);
       return APIError::BAD_INDICATOR;
@@ -233,7 +205,10 @@ APIError APINoiseFrameHelper::try_read_frame_() {
   // During handshake, rx_buf_.size() is used in prologue construction, so
   // the buffer must be exactly msg_size to avoid prologue mismatch.)
   uint16_t alloc_size = msg_size + (is_data ? RX_BUF_NULL_TERMINATOR : 0);
-  this->rx_buf_.resize(alloc_size);
+  if (!this->rx_buf_.resize(alloc_size)) [[unlikely]] {
+    state_ = State::FAILED;
+    return APIError::OUT_OF_MEMORY;
+  }
 
   if (rx_buf_len_ < msg_size) {
     // more data to read
@@ -300,7 +275,10 @@ APIError APINoiseFrameHelper::state_action_client_hello_() {
   // Resize for: existing prologue + 2 size bytes + frame data
   size_t old_size = this->prologue_.size();
   size_t rx_size = this->rx_buf_.size();
-  this->prologue_.resize(old_size + 2 + rx_size);
+  if (!this->prologue_.resize(old_size + 2 + rx_size)) [[unlikely]] {
+    state_ = State::FAILED;
+    return APIError::OUT_OF_MEMORY;
+  }
   this->prologue_[old_size] = (uint8_t) (rx_size >> 8);
   this->prologue_[old_size + 1] = (uint8_t) rx_size;
   if (rx_size > 0) {
@@ -348,15 +326,15 @@ APIError APINoiseFrameHelper::state_action_server_hello_() {
   return APIError::OK;
 }
 APIError APINoiseFrameHelper::state_action_handshake_() {
-  int action = noise_handshakestate_get_action(this->handshake_);
-  if (action == NOISE_ACTION_READ_MESSAGE) {
+  noise::NoiseResponderHandshake::Action action = this->handshake_.action();
+  if (action == noise::NoiseResponderHandshake::Action::ACTION_READ) {
     return this->state_action_handshake_read_();
-  } else if (action == NOISE_ACTION_WRITE_MESSAGE) {
+  } else if (action == noise::NoiseResponderHandshake::Action::ACTION_WRITE) {
     return this->state_action_handshake_write_();
   }
   // bad state for action
   this->state_ = State::FAILED;
-  HELPER_LOG("Bad action for handshake: %d", action);
+  HELPER_LOG("Bad action for handshake: %d", (int) action);
   return APIError::HANDSHAKESTATE_BAD_STATE;
 }
 APIError APINoiseFrameHelper::state_action_handshake_read_() {
@@ -368,20 +346,16 @@ APIError APINoiseFrameHelper::state_action_handshake_read_() {
   if (this->rx_buf_.empty()) {
     this->send_explicit_handshake_reject_(LOG_STR("Empty handshake message"));
     return APIError::BAD_HANDSHAKE_ERROR_BYTE;
-  } else if (this->rx_buf_[0] != 0x00) {
+  } else if (this->rx_buf_[0] != noise::HANDSHAKE_STATUS_OK) {
     HELPER_LOG("Bad handshake error byte: %u", this->rx_buf_[0]);
     this->send_explicit_handshake_reject_(LOG_STR("Bad handshake error byte"));
     return APIError::BAD_HANDSHAKE_ERROR_BYTE;
   }
 
-  NoiseBuffer mbuf;
-  noise_buffer_init(mbuf);
-  noise_buffer_set_input(mbuf, this->rx_buf_.data() + 1, this->rx_buf_.size() - 1);
-  int err = noise_handshakestate_read_message(this->handshake_, &mbuf, nullptr);
+  int err = this->handshake_.read_message(this->rx_buf_.data() + 1, this->rx_buf_.size() - 1);
   if (err != 0) {
     // Special handling for MAC failure
-    this->send_explicit_handshake_reject_(err == NOISE_ERROR_MAC_FAILURE ? LOG_STR("Handshake MAC failure")
-                                                                         : LOG_STR("Handshake error"));
+    this->send_explicit_handshake_reject_(noise::reject_reason_for(err));
     return this->handle_noise_error_(err, LOG_STR("noise_handshakestate_read_message"),
                                      APIError::HANDSHAKESTATE_READ_FAILED);
   }
@@ -390,18 +364,16 @@ APIError APINoiseFrameHelper::state_action_handshake_read_() {
 }
 APIError APINoiseFrameHelper::state_action_handshake_write_() {
   uint8_t buffer[65];
-  NoiseBuffer mbuf;
-  noise_buffer_init(mbuf);
-  noise_buffer_set_output(mbuf, buffer + 1, sizeof(buffer) - 1);
+  size_t msg_len = 0;
 
-  int err = noise_handshakestate_write_message(this->handshake_, &mbuf, nullptr);
+  int err = this->handshake_.write_message(buffer + 1, sizeof(buffer) - 1, msg_len);
   APIError aerr = this->handle_noise_error_(err, LOG_STR("noise_handshakestate_write_message"),
                                             APIError::HANDSHAKESTATE_WRITE_FAILED);
   if (aerr != APIError::OK)
     return aerr;
-  buffer[0] = 0x00;  // success
+  buffer[0] = noise::HANDSHAKE_STATUS_OK;
 
-  aerr = this->write_frame_(buffer, mbuf.size + 1);
+  aerr = this->write_frame_(buffer, msg_len + 1);
   if (aerr != APIError::OK)
     return aerr;
   return this->check_handshake_finished_();
@@ -409,33 +381,22 @@ APIError APINoiseFrameHelper::state_action_handshake_write_() {
 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));
-  reason_len = std::min(reason_len, sizeof(data) - 1);
-  if (reason_len > 0) {
-    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);
-  reason_len = std::min(reason_len, sizeof(data) - 1);
-  if (reason_len > 0) {
-    // 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;
+  static_assert(sizeof(data) >= noise::MAC_FAILURE_PAYLOAD_SIZE,
+                "reject buffer must fit the MAC failure wire contract");
+  size_t data_size = noise::format_reject_payload(data, sizeof(data), reason);
 
   // temporarily remove failed state
   auto orig_state = state_;
   state_ = State::EXPLICIT_REJECT;
-  write_frame_(data, data_size);
-  state_ = orig_state;
+  APIError aerr = write_frame_(data, data_size);
+  if (aerr != APIError::OK) {
+    // Best effort; the reject reason is a diagnosis aid, not a protocol step
+    ESP_LOGW(TAG, "Sending handshake reject failed: %d", (int) aerr);
+  }
+  if (state_ == State::EXPLICIT_REJECT) {
+    // write_frame_ may have moved the state to FAILED; keep that decision
+    state_ = orig_state;
+  }
 }
 APIError APINoiseFrameHelper::read_packet(ReadPacketBuffer *buffer) {
   APIError aerr = this->check_data_state_();
@@ -490,14 +451,12 @@ APIError APINoiseFrameHelper::read_packet(ReadPacketBuffer *buffer) {
 }
 // Encrypt a single noise message in place and return the encrypted frame length.
 // Returns APIError::OK on success.
-APIError APINoiseFrameHelper::encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint8_t message_type,
+APIError APINoiseFrameHelper::encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint16_t message_type,
                                                      uint16_t &encrypted_len_out) {
-  // Write noise header
-  buf_start[0] = 0x01;  // indicator
-  // buf_start[1], buf_start[2] to be set after encryption
+  // The noise frame header is written after encryption, when the size is known
 
   // Write message header (to be encrypted)
-  constexpr uint8_t msg_offset = 3;
+  constexpr uint8_t msg_offset = noise::FRAME_HEADER_SIZE;
   buf_start[msg_offset] = static_cast<uint8_t>(message_type >> 8);      // type high byte
   buf_start[msg_offset + 1] = static_cast<uint8_t>(message_type);       // type low byte
   buf_start[msg_offset + 2] = static_cast<uint8_t>(payload_size >> 8);  // data_len high byte
@@ -515,26 +474,27 @@ APIError APINoiseFrameHelper::encrypt_noise_message_(uint8_t *buf_start, uint16_
   if (aerr != APIError::OK)
     return aerr;
 
-  // Fill in the encrypted size
-  buf_start[1] = static_cast<uint8_t>(mbuf.size >> 8);
-  buf_start[2] = static_cast<uint8_t>(mbuf.size);
+  // Fill in the frame header now that the encrypted size is known
+  noise::write_frame_header(buf_start, static_cast<uint16_t>(mbuf.size));
 
-  encrypted_len_out = static_cast<uint16_t>(3 + mbuf.size);  // indicator + size + encrypted data
+  encrypted_len_out = static_cast<uint16_t>(noise::FRAME_HEADER_SIZE + mbuf.size);
   return APIError::OK;
 }
 
-APIError APINoiseFrameHelper::write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) {
+APIError APINoiseFrameHelper::write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) {
 #ifdef ESPHOME_DEBUG_API
   assert(this->state_ == State::DATA);
 #endif
 
+  APIBuffer *buf = buffer.get_buffer();
   // Resize buffer to include footer space for Noise MAC
-  if (this->frame_footer_size_)
-    buffer.get_buffer()->resize(buffer.get_buffer()->size() + this->frame_footer_size_);
+  if (this->frame_footer_size_ && !buf->resize(buf->size() + this->frame_footer_size_)) [[unlikely]] {
+    state_ = State::FAILED;
+    return APIError::OUT_OF_MEMORY;
+  }
 
-  uint16_t payload_size =
-      static_cast<uint16_t>(buffer.get_buffer()->size() - HEADER_PADDING - this->frame_footer_size_);
-  uint8_t *buf_start = buffer.get_buffer()->data();
+  uint16_t payload_size = static_cast<uint16_t>(buf->size() - HEADER_PADDING - this->frame_footer_size_);
+  uint8_t *buf_start = buf->data();
   uint16_t encrypted_len;
   APIError aerr = this->encrypt_noise_message_(buf_start, payload_size, type, encrypted_len);
   if (aerr != APIError::OK)
@@ -568,21 +528,19 @@ APIError APINoiseFrameHelper::write_protobuf_messages(ProtoWriteBuffer buffer, s
 }
 
 APIError APINoiseFrameHelper::write_frame_(const uint8_t *data, uint16_t len) {
-  uint8_t header[3];
-  header[0] = 0x01;  // indicator
-  header[1] = (uint8_t) (len >> 8);
-  header[2] = (uint8_t) len;
+  uint8_t header[noise::FRAME_HEADER_SIZE];
+  noise::write_frame_header(header, len);
 
   if (len == 0) {
-    return this->write_raw_buf_(header, 3);
+    return this->write_raw_buf_(header, noise::FRAME_HEADER_SIZE);
   }
   struct iovec iov[2];
   iov[0].iov_base = header;
-  iov[0].iov_len = 3;
+  iov[0].iov_len = noise::FRAME_HEADER_SIZE;
   iov[1].iov_base = const_cast<uint8_t *>(data);
   iov[1].iov_len = len;
 
-  return this->write_raw_iov_(iov, 2, 3 + len);
+  return this->write_raw_iov_(iov, 2, noise::FRAME_HEADER_SIZE + len);
 }
 
 /** Initiate the data structures for the handshake.
@@ -590,45 +548,12 @@ APIError APINoiseFrameHelper::write_frame_(const uint8_t *data, uint16_t len) {
  * @return 0 on success, -1 on error (check errno)
  */
 APIError APINoiseFrameHelper::init_handshake_() {
-  int err;
-  // Noise_NNpsk0_25519_ChaChaPoly_SHA256, built on the stack:
-  // noise_handshakestate_new_by_id copies it, so a member would waste
-  // 104 bytes per connection, and a static const would sit in RAM on
-  // ESP8266 (.rodata is DRAM there).
-  const NoiseProtocolId nid = {
-      .prefix_id = NOISE_PREFIX_STANDARD,
-      .pattern_id = NOISE_PATTERN_NN,
-      .modifier_ids = {NOISE_MODIFIER_PSK0},
-      .dh_id = NOISE_DH_CURVE25519,
-      .cipher_id = NOISE_CIPHER_CHACHAPOLY,
-      .hash_id = NOISE_HASH_SHA256,
-      .hybrid_id = NOISE_DH_NONE,
-  };
-
-  err = noise_handshakestate_new_by_id(&handshake_, &nid, NOISE_ROLE_RESPONDER);
-  APIError aerr =
-      handle_noise_error_(err, LOG_STR("noise_handshakestate_new_by_id"), APIError::HANDSHAKESTATE_SETUP_FAILED);
+  int err = this->handshake_.init(this->ctx_.get_psk(), prologue_.data(), prologue_.size());
+  APIError aerr = handle_noise_error_(err, LOG_STR("noise_handshake_init"), APIError::HANDSHAKESTATE_SETUP_FAILED);
   if (aerr != APIError::OK)
     return aerr;
-
-  const auto &psk = this->ctx_.get_psk();
-  err = noise_handshakestate_set_pre_shared_key(handshake_, psk.data(), psk.size());
-  aerr = handle_noise_error_(err, LOG_STR("noise_handshakestate_set_pre_shared_key"),
-                             APIError::HANDSHAKESTATE_SETUP_FAILED);
-  if (aerr != APIError::OK)
-    return aerr;
-
-  err = noise_handshakestate_set_prologue(handshake_, prologue_.data(), prologue_.size());
-  aerr = handle_noise_error_(err, LOG_STR("noise_handshakestate_set_prologue"), APIError::HANDSHAKESTATE_SETUP_FAILED);
-  if (aerr != APIError::OK)
-    return aerr;
-  // set_prologue copies it into handshakestate, so we can get rid of it now
+  // init copies the prologue into the handshakestate, so we can get rid of it now
   prologue_.release();
-
-  err = noise_handshakestate_start(handshake_);
-  aerr = handle_noise_error_(err, LOG_STR("noise_handshakestate_start"), APIError::HANDSHAKESTATE_SETUP_FAILED);
-  if (aerr != APIError::OK)
-    return aerr;
   return APIError::OK;
 }
 
@@ -637,15 +562,17 @@ APIError APINoiseFrameHelper::check_handshake_finished_() {
   assert(state_ == State::HANDSHAKE);
 #endif
 
-  int action = noise_handshakestate_get_action(handshake_);
-  if (action == NOISE_ACTION_READ_MESSAGE || action == NOISE_ACTION_WRITE_MESSAGE)
+  noise::NoiseResponderHandshake::Action action = this->handshake_.action();
+  if (action == noise::NoiseResponderHandshake::Action::ACTION_READ ||
+      action == noise::NoiseResponderHandshake::Action::ACTION_WRITE)
     return APIError::OK;
-  if (action != NOISE_ACTION_SPLIT) {
+  if (action != noise::NoiseResponderHandshake::Action::ACTION_SPLIT) {
     state_ = State::FAILED;
-    HELPER_LOG("Bad action for handshake: %d", action);
+    HELPER_LOG("Bad action for handshake: %d", (int) action);
     return APIError::HANDSHAKESTATE_BAD_STATE;
   }
-  int err = noise_handshakestate_split(handshake_, &send_cipher_, &recv_cipher_);
+  // split() also frees the handshake state
+  int err = this->handshake_.split(send_cipher_, recv_cipher_);
   APIError aerr =
       handle_noise_error_(err, LOG_STR("noise_handshakestate_split"), APIError::HANDSHAKESTATE_SPLIT_FAILED);
   if (aerr != APIError::OK)
@@ -654,17 +581,11 @@ APIError APINoiseFrameHelper::check_handshake_finished_() {
   this->frame_footer_size_ = noise_cipherstate_get_mac_length(send_cipher_);
 
   HELPER_LOG("Handshake complete!");
-  noise_handshakestate_free(handshake_);
-  handshake_ = nullptr;
   state_ = State::DATA;
   return APIError::OK;
 }
 
 APINoiseFrameHelper::~APINoiseFrameHelper() {
-  if (handshake_ != nullptr) {
-    noise_handshakestate_free(handshake_);
-    handshake_ = nullptr;
-  }
   if (send_cipher_ != nullptr) {
     noise_cipherstate_free(send_cipher_);
     send_cipher_ = nullptr;
@@ -675,16 +596,6 @@ APINoiseFrameHelper::~APINoiseFrameHelper() {
   }
 }
 
-extern "C" {
-// declare how noise generates random bytes (here with a good HWRNG based on the RF system)
-void noise_rand_bytes(void *output, size_t len) {
-  if (!esphome::random_bytes(reinterpret_cast<uint8_t *>(output), len)) {
-    ESP_LOGE(TAG, "Acquiring random bytes failed; rebooting");
-    arch_restart();
-  }
-}
-}
-
 }  // namespace esphome::api
 #endif  // USE_API_NOISE
 #endif  // USE_API

esphome/components/api/api_frame_helper_noise.h

@@ -3,7 +3,7 @@
 #ifdef USE_API
 #ifdef USE_API_NOISE
 #include "noise/protocol.h"
-#include "api_noise_context.h"
+#include "esphome/components/noise/noise_handshake.h"
 
 namespace esphome::api {
 
@@ -14,9 +14,9 @@ class APINoiseFrameHelper final : public APIFrameHelper {
   // Pos 1-2: encrypted payload size (16-bit big-endian)
   // Pos 3-6: encrypted type (16-bit) + data_len (16-bit)
   // Pos 7+: actual payload data
-  static constexpr uint8_t HEADER_PADDING = 1 + 2 + 2 + 2;  // indicator + size + type + data_len
+  static constexpr uint8_t HEADER_PADDING = noise::FRAME_HEADER_SIZE + 2 + 2;  // frame header + type + data_len
 
-  APINoiseFrameHelper(std::unique_ptr<socket::Socket> socket, APINoiseContext &ctx)
+  APINoiseFrameHelper(std::unique_ptr<socket::Socket> socket, noise::NoiseContext &ctx)
       : APIFrameHelper(std::move(socket)), ctx_(ctx) {
     frame_header_padding_ = HEADER_PADDING;
   }
@@ -31,7 +31,7 @@ class APINoiseFrameHelper final : public APIFrameHelper {
 #endif
   APIError loop() override;
   APIError read_packet(ReadPacketBuffer *buffer) override;
-  APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) override;
+  APIError write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) override;
   APIError write_protobuf_messages(ProtoWriteBuffer buffer, std::span<const MessageInfo> messages) override;
 
  protected:
@@ -44,7 +44,7 @@ class APINoiseFrameHelper final : public APIFrameHelper {
   APIError state_action_handshake_write_();
   APIError try_read_frame_();
   APIError write_frame_(const uint8_t *data, uint16_t len);
-  APIError encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint8_t message_type,
+  APIError encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint16_t message_type,
                                   uint16_t &encrypted_len_out);
   APIError init_handshake_();
   APIError check_handshake_finished_();
@@ -52,13 +52,13 @@ class APINoiseFrameHelper final : public APIFrameHelper {
   APIError handle_handshake_frame_error_(APIError aerr);
   APIError handle_noise_error_(int err, const LogString *func_name, APIError api_err);
 
-  // Pointers first (4 bytes each)
-  NoiseHandshakeState *handshake_{nullptr};
+  // Pointers first (4 bytes each; the handshake wrapper holds one pointer)
+  noise::NoiseResponderHandshake handshake_;
   NoiseCipherState *send_cipher_{nullptr};
   NoiseCipherState *recv_cipher_{nullptr};
 
   // Reference to noise context (4 bytes on 32-bit)
-  APINoiseContext &ctx_;
+  noise::NoiseContext &ctx_;
 
   // Buffer for noise handshake prologue (released after handshake)
   APIBuffer prologue_;
@@ -67,7 +67,7 @@ class APINoiseFrameHelper final : public APIFrameHelper {
   // Fixed-size header buffer for noise protocol:
   // 1 byte for indicator + 2 bytes for message size (16-bit value, not varint)
   // Note: Maximum message size is UINT16_MAX (65535), with a limit of 128 bytes during handshake phase
-  uint8_t rx_header_buf_[3];
+  uint8_t rx_header_buf_[noise::FRAME_HEADER_SIZE];
   uint8_t rx_header_buf_len_ = 0;
   // 4 bytes total, no padding
 };

esphome/components/api/api_frame_helper_plaintext.cpp

@@ -5,6 +5,7 @@
 #include "esphome/core/hal.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
+#include "api_pb2.h"
 #include "proto.h"
 #include <cstring>
 #include <cinttypes>
@@ -171,7 +172,10 @@ APIError APIPlaintextFrameHelper::try_read_frame_() {
 
   // Reserve space for body (+ null terminator so protobuf StringRef fields
   // can be safely null-terminated in-place after decode)
-  this->rx_buf_.resize(this->rx_header_parsed_len_ + RX_BUF_NULL_TERMINATOR);
+  if (!this->rx_buf_.resize(this->rx_header_parsed_len_ + RX_BUF_NULL_TERMINATOR)) [[unlikely]] {
+    state_ = State::FAILED;
+    return APIError::OUT_OF_MEMORY;
+  }
 
   if (rx_buf_len_ < rx_header_parsed_len_) {
     // more data to read
@@ -252,24 +256,21 @@ ESPHOME_ALWAYS_INLINE static inline void encode_varint_16(uint16_t value, uint8_
   *p = static_cast<uint8_t>(value);
 }
 
-// Encode an 8-bit varint (1-2 bytes) using pre-computed length.
-ESPHOME_ALWAYS_INLINE static inline void encode_varint_8(uint8_t value, uint8_t varint_len, uint8_t *p) {
-  if (varint_len == 2) {
-    *p++ = static_cast<uint8_t>(value | 0x80);
-    *p = static_cast<uint8_t>(value >> 7);
-  } else {
-    *p = value;
-  }
-}
+// The generator rejects message IDs above MAX_MESSAGE_TYPE, so the type varint
+// can never outgrow the 2 bytes HEADER_PADDING budgets for it. Without this
+// bound, write_plaintext_header's header_offset would underflow for the first
+// message in a batch and the header write would land outside the buffer.
+static_assert(1 + 3 + ProtoSize::varint16(MAX_MESSAGE_TYPE) <= APIPlaintextFrameHelper::HEADER_PADDING,
+              "HEADER_PADDING cannot fit the type varint of the largest message ID");
 
 // Write plaintext header into pre-allocated padding before payload.
 // padding_size: bytes reserved before payload (HEADER_PADDING for first/single msg,
 //               actual header size for contiguous batch messages).
 // Returns the total header length (indicator + varints).
 ESPHOME_ALWAYS_INLINE static inline uint8_t write_plaintext_header(uint8_t *buf_start, uint16_t payload_size,
-                                                                   uint8_t message_type, uint8_t padding_size) {
+                                                                   uint16_t message_type, uint8_t padding_size) {
   uint8_t size_varint_len = ProtoSize::varint16(payload_size);
-  uint8_t type_varint_len = ProtoSize::varint8(message_type);
+  uint8_t type_varint_len = ProtoSize::varint16(message_type);
   uint8_t total_header_len = 1 + size_varint_len + type_varint_len;
 
   // The header is right-justified within the padding so it sits immediately before payload.
@@ -292,12 +293,12 @@ ESPHOME_ALWAYS_INLINE static inline uint8_t write_plaintext_header(uint8_t *buf_
 
   // Encode varints directly into buffer using pre-computed lengths
   encode_varint_16(payload_size, size_varint_len, buf_start + header_offset + 1);
-  encode_varint_8(message_type, type_varint_len, buf_start + header_offset + 1 + size_varint_len);
+  encode_varint_16(message_type, type_varint_len, buf_start + header_offset + 1 + size_varint_len);
 
   return total_header_len;
 }
 
-APIError APIPlaintextFrameHelper::write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) {
+APIError APIPlaintextFrameHelper::write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) {
 #ifdef ESPHOME_DEBUG_API
   assert(this->state_ == State::DATA);
 #endif

esphome/components/api/api_frame_helper_plaintext.h

@@ -10,7 +10,8 @@ class APIPlaintextFrameHelper final : public APIFrameHelper {
   // Plaintext header structure (worst case):
   // Pos 0: indicator (0x00)
   // Pos 1-3: payload size varint (up to 3 bytes)
-  // Pos 4-5: message type varint (up to 2 bytes)
+  // Pos 4-5: message type varint (up to 2 bytes; covers message IDs up to
+  //          16383, enforced by the proto codegen)
   // Pos 6+: actual payload data
   static constexpr uint8_t HEADER_PADDING = 1 + 3 + 2;  // indicator + size varint + type varint
 
@@ -21,7 +22,7 @@ class APIPlaintextFrameHelper final : public APIFrameHelper {
   APIError init() override;
   APIError loop() override;
   APIError read_packet(ReadPacketBuffer *buffer) override;
-  APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) override;
+  APIError write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) override;
   APIError write_protobuf_messages(ProtoWriteBuffer buffer, std::span<const MessageInfo> messages) override;
 #ifdef USE_API_NOISE
   // After try_read_frame_ returned PROTOCOL_SWITCH_TO_NOISE: copy out the

esphome/components/api/api_noise_context.h

@@ -1,37 +0,0 @@
-#pragma once
-#include <array>
-#include <cstdint>
-#include "esphome/core/defines.h"
-
-namespace esphome::api {
-
-#ifdef USE_API_NOISE
-using psk_t = std::array<uint8_t, 32>;
-
-class APINoiseContext {
- public:
-  // The all-zeros PSK is reserved: it marks the device as unprovisioned and
-  // doubles as the well-known provisioning PSK that unprovisioned devices
-  // accept for Noise handshakes (passive-sniffing protection only, no
-  // authentication). It is never a valid real key.
-  static bool is_all_zeros(const psk_t &psk) {
-    uint8_t acc = 0;
-    for (uint8_t b : psk) {
-      acc |= b;
-    }
-    return acc == 0;
-  }
-  void set_psk(psk_t psk) {
-    this->psk_ = psk;
-    this->has_psk_ = !is_all_zeros(psk);
-  }
-  const psk_t &get_psk() const { return this->psk_; }
-  bool has_psk() const { return this->has_psk_; }
-
- protected:
-  psk_t psk_{};
-  bool has_psk_{false};
-};
-#endif  // USE_API_NOISE
-
-}  // namespace esphome::api

esphome/components/api/api_options.proto

@@ -116,4 +116,10 @@ extend google.protobuf.FieldOptions {
     // the per-byte loop when the upper bits are non-zero (the common case
     // for real MAC addresses, since OUIs occupy the top 24 bits).
     optional bool mac_address = 50019 [default=false];
+
+    // track_presence: Track whether this message-typed field was present on the wire.
+    // Generates a `bool has_<field>{false};` member on the decoding side that is set
+    // to true when the field arrives, so an all-default submessage can be told apart
+    // from an absent one (e.g. a UTC ParsedTimezone, which is all zeros).
+    optional bool track_presence = 50020 [default=false];
 }

esphome/components/api/api_overflow_buffer.cpp

@@ -1,6 +1,7 @@
 #include "api_overflow_buffer.h"
 #ifdef USE_API
 #include <cstring>
+#include <new>
 
 namespace esphome::api {
 
@@ -61,9 +62,18 @@ bool APIOverflowBuffer::enqueue_iov(const struct iovec *iov, int iovcnt, uint16_
     return false;
 
   uint16_t buffer_size = total_len - skip;
+  // nothrow: a failed allocation returns nullptr so the connection is dropped
+  // cleanly instead of plain new's crash or abort on OOM
   // NOLINTNEXTLINE(cppcoreguidelines-owning-memory)
-  auto *entry = new Entry{new uint8_t[buffer_size], buffer_size, 0};
-  this->queue_[this->tail_] = entry;
+  auto *data = new (std::nothrow) uint8_t[buffer_size];
+  if (data == nullptr)
+    return false;
+  // NOLINTNEXTLINE(cppcoreguidelines-owning-memory)
+  auto *entry = new (std::nothrow) Entry{data, buffer_size, 0};
+  if (entry == nullptr) {
+    delete[] data;
+    return false;
+  }
 
   uint16_t to_skip = skip;
   uint16_t write_pos = 0;
@@ -80,6 +90,8 @@ bool APIOverflowBuffer::enqueue_iov(const struct iovec *iov, int iovcnt, uint16_
     }
   }
 
+  // Publish only after the copy completes so a half-built entry is never reachable
+  this->queue_[this->tail_] = entry;
   this->tail_ = (this->tail_ + 1) % API_MAX_SEND_QUEUE;
   this->count_++;
   return true;

esphome/components/api/api_overflow_buffer.h

@@ -61,7 +61,7 @@ class APIOverflowBuffer {
 
   /// Enqueue unsent IOV data into the backlog.
   /// Copies iov data starting at byte offset `skip` into a new entry.
-  /// Returns false if the queue is full (caller should fail the connection).
+  /// Returns false if the queue is full or allocation fails (caller should fail the connection).
   bool enqueue_iov(const struct iovec *iov, int iovcnt, uint16_t total_len, uint16_t skip);
 
  protected:

esphome/components/api/api_pb2.cpp

@@ -102,12 +102,14 @@ uint8_t *SerialProxyInfo::encode(ProtoWriteBuffer &buffer PROTO_ENCODE_DEBUG_PAR
   uint8_t *__restrict__ pos = buffer.get_pos();
   ProtoEncode::encode_string(pos PROTO_ENCODE_DEBUG_ARG, 1, this->name);
   ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 2, static_cast<uint32_t>(this->port_type));
+  ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 3, this->configured_line_states);
   return pos;
 }
 uint32_t SerialProxyInfo::calculate_size() const {
   uint32_t size = 0;
   size += ProtoSize::calc_length(1, this->name.size());
   size += this->port_type ? 2 : 0;
+  size += ProtoSize::calc_uint32(1, this->configured_line_states);
   return size;
 }
 #endif
@@ -1249,12 +1251,9 @@ bool ParsedTimezone::decode_length(uint32_t field_id, ProtoLengthDelimited value
 }
 bool GetTimeResponse::decode_length(uint32_t field_id, ProtoLengthDelimited value) {
   switch (field_id) {
-    case 2: {
-      this->timezone = StringRef(reinterpret_cast<const char *>(value.data()), value.size());
-      break;
-    }
     case 3:
       value.decode_to_message(this->parsed_timezone);
+      this->has_parsed_timezone = true;
       break;
     default:
       return false;
@@ -2324,7 +2323,6 @@ uint8_t *ListEntitiesMediaPlayerResponse::encode(ProtoWriteBuffer &buffer PROTO_
 #endif
   ProtoEncode::encode_bool(pos PROTO_ENCODE_DEBUG_ARG, 6, this->disabled_by_default);
   ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 7, static_cast<uint32_t>(this->entity_category));
-  ProtoEncode::encode_bool(pos PROTO_ENCODE_DEBUG_ARG, 8, this->supports_pause);
   for (auto &it : this->supported_formats) {
     ProtoEncode::encode_sub_message(pos PROTO_ENCODE_DEBUG_ARG, buffer, 9, it);
   }
@@ -2344,7 +2342,6 @@ uint32_t ListEntitiesMediaPlayerResponse::calculate_size() const {
 #endif
   size += ProtoSize::calc_bool(1, this->disabled_by_default);
   size += this->entity_category ? 2 : 0;
-  size += ProtoSize::calc_bool(1, this->supports_pause);
   if (!this->supported_formats.empty()) {
     for (const auto &it : this->supported_formats) {
       size += ProtoSize::calc_message_force(1, it.calculate_size());
@@ -3945,6 +3942,18 @@ uint32_t ZWaveProxyRequest::calculate_size() const {
   size += ProtoSize::calc_length(1, this->data_len);
   return size;
 }
+uint8_t *ZWaveProxyRequestResponse::encode(ProtoWriteBuffer &buffer PROTO_ENCODE_DEBUG_PARAM) const {
+  uint8_t *__restrict__ pos = buffer.get_pos();
+  ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 1, static_cast<uint32_t>(this->type));
+  ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 2, static_cast<uint32_t>(this->status));
+  return pos;
+}
+uint32_t ZWaveProxyRequestResponse::calculate_size() const {
+  uint32_t size = 0;
+  size += this->type ? 2 : 0;
+  size += this->status ? 2 : 0;
+  return size;
+}
 #endif
 #ifdef USE_INFRARED
 uint8_t *ListEntitiesInfraredResponse::encode(ProtoWriteBuffer &buffer PROTO_ENCODE_DEBUG_PARAM) const {
@@ -4187,12 +4196,14 @@ uint8_t *SerialProxyGetModemPinsResponse::encode(ProtoWriteBuffer &buffer PROTO_
   uint8_t *__restrict__ pos = buffer.get_pos();
   ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 1, this->instance);
   ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 2, this->line_states);
+  ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 3, static_cast<uint32_t>(this->status));
   return pos;
 }
 uint32_t SerialProxyGetModemPinsResponse::calculate_size() const {
   uint32_t size = 0;
   size += ProtoSize::calc_uint32(1, this->instance);
   size += ProtoSize::calc_uint32(1, this->line_states);
+  size += this->status ? 2 : 0;
   return size;
 }
 bool SerialProxyRequest::decode_varint(uint32_t field_id, proto_varint_value_t value) {

esphome/components/api/api_pb2_dump.cpp

@@ -816,6 +816,18 @@ template<> const char *proto_enum_to_string<enums::ZWaveProxyRequestType>(enums:
       return ESPHOME_PSTR("UNKNOWN");
   }
 }
+template<> const char *proto_enum_to_string<enums::ZWaveProxyStatus>(enums::ZWaveProxyStatus value) {
+  switch (value) {
+    case enums::ZWAVE_PROXY_STATUS_OK:
+      return ESPHOME_PSTR("ZWAVE_PROXY_STATUS_OK");
+    case enums::ZWAVE_PROXY_STATUS_IN_USE:
+      return ESPHOME_PSTR("ZWAVE_PROXY_STATUS_IN_USE");
+    case enums::ZWAVE_PROXY_STATUS_NOT_SUPPORTED:
+      return ESPHOME_PSTR("ZWAVE_PROXY_STATUS_NOT_SUPPORTED");
+    default:
+      return ESPHOME_PSTR("UNKNOWN");
+  }
+}
 #endif
 #ifdef USE_SERIAL_PROXY
 template<> const char *proto_enum_to_string<enums::SerialProxyParity>(enums::SerialProxyParity value) {
@@ -838,6 +850,10 @@ template<> const char *proto_enum_to_string<enums::SerialProxyRequestType>(enums
       return ESPHOME_PSTR("SERIAL_PROXY_REQUEST_TYPE_UNSUBSCRIBE");
     case enums::SERIAL_PROXY_REQUEST_TYPE_FLUSH:
       return ESPHOME_PSTR("SERIAL_PROXY_REQUEST_TYPE_FLUSH");
+    case enums::SERIAL_PROXY_REQUEST_TYPE_CONFIGURE:
+      return ESPHOME_PSTR("SERIAL_PROXY_REQUEST_TYPE_CONFIGURE");
+    case enums::SERIAL_PROXY_REQUEST_TYPE_SET_MODEM_PINS:
+      return ESPHOME_PSTR("SERIAL_PROXY_REQUEST_TYPE_SET_MODEM_PINS");
     default:
       return ESPHOME_PSTR("UNKNOWN");
   }
@@ -854,6 +870,10 @@ template<> const char *proto_enum_to_string<enums::SerialProxyStatus>(enums::Ser
       return ESPHOME_PSTR("SERIAL_PROXY_STATUS_TIMEOUT");
     case enums::SERIAL_PROXY_STATUS_NOT_SUPPORTED:
       return ESPHOME_PSTR("SERIAL_PROXY_STATUS_NOT_SUPPORTED");
+    case enums::SERIAL_PROXY_STATUS_PORT_IN_USE:
+      return ESPHOME_PSTR("SERIAL_PROXY_STATUS_PORT_IN_USE");
+    case enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT:
+      return ESPHOME_PSTR("SERIAL_PROXY_STATUS_INVALID_ARGUMENT");
     default:
       return ESPHOME_PSTR("UNKNOWN");
   }
@@ -914,6 +934,7 @@ const char *SerialProxyInfo::dump_to(DumpBuffer &out) const {
   MessageDumpHelper helper(out, ESPHOME_PSTR("SerialProxyInfo"));
   dump_field(out, ESPHOME_PSTR("name"), this->name);
   dump_field(out, ESPHOME_PSTR("port_type"), static_cast<enums::SerialProxyPortType>(this->port_type));
+  dump_field(out, ESPHOME_PSTR("configured_line_states"), this->configured_line_states);
   return out.c_str();
 }
 #endif
@@ -1468,7 +1489,7 @@ const char *ParsedTimezone::dump_to(DumpBuffer &out) const {
 const char *GetTimeResponse::dump_to(DumpBuffer &out) const {
   MessageDumpHelper helper(out, ESPHOME_PSTR("GetTimeResponse"));
   dump_field(out, ESPHOME_PSTR("epoch_seconds"), this->epoch_seconds);
-  dump_field(out, ESPHOME_PSTR("timezone"), this->timezone);
+  dump_field(out, ESPHOME_PSTR("has_parsed_timezone"), this->has_parsed_timezone);
   out.append(2, ' ').append_p(ESPHOME_PSTR("parsed_timezone")).append(": ");
   this->parsed_timezone.dump_to(out);
   out.append("\n");
@@ -1941,7 +1962,6 @@ const char *ListEntitiesMediaPlayerResponse::dump_to(DumpBuffer &out) const {
 #endif
   dump_field(out, ESPHOME_PSTR("disabled_by_default"), this->disabled_by_default);
   dump_field(out, ESPHOME_PSTR("entity_category"), static_cast<enums::EntityCategory>(this->entity_category));
-  dump_field(out, ESPHOME_PSTR("supports_pause"), this->supports_pause);
   for (const auto &it : this->supported_formats) {
     out.append(4, ' ').append_p(ESPHOME_PSTR("supported_formats")).append(": ");
     it.dump_to(out);
@@ -2644,6 +2664,12 @@ const char *ZWaveProxyRequest::dump_to(DumpBuffer &out) const {
   dump_bytes_field(out, ESPHOME_PSTR("data"), this->data, this->data_len);
   return out.c_str();
 }
+const char *ZWaveProxyRequestResponse::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, ESPHOME_PSTR("ZWaveProxyRequestResponse"));
+  dump_field(out, ESPHOME_PSTR("type"), static_cast<enums::ZWaveProxyRequestType>(this->type));
+  dump_field(out, ESPHOME_PSTR("status"), static_cast<enums::ZWaveProxyStatus>(this->status));
+  return out.c_str();
+}
 #endif
 #ifdef USE_INFRARED
 const char *ListEntitiesInfraredResponse::dump_to(DumpBuffer &out) const {
@@ -2753,6 +2779,7 @@ const char *SerialProxyGetModemPinsResponse::dump_to(DumpBuffer &out) const {
   MessageDumpHelper helper(out, ESPHOME_PSTR("SerialProxyGetModemPinsResponse"));
   dump_field(out, ESPHOME_PSTR("instance"), this->instance);
   dump_field(out, ESPHOME_PSTR("line_states"), this->line_states);
+  dump_field(out, ESPHOME_PSTR("status"), static_cast<enums::SerialProxyStatus>(this->status));
   return out.c_str();
 }
 const char *SerialProxyRequest::dump_to(DumpBuffer &out) const {

esphome/components/api/api_server.cpp

@@ -588,7 +588,7 @@ bool APIServer::load_and_apply_noise_psk_() {
   return true;
 }
 
-bool APIServer::save_noise_psk(psk_t psk, bool make_active) {
+bool APIServer::save_noise_psk(noise::psk_t psk, bool make_active) {
 #ifdef USE_API_NOISE_PSK_FROM_YAML
   // When PSK is set from YAML, this function should never be called
   // but if it is, reject the change

esphome/components/api/api_server.h

@@ -5,7 +5,10 @@
 #include "api_buffer.h"
 // Must precede clients_ so APIConnection is complete for default_delete (libc++).
 #include "api_connection.h"
-#include "api_noise_context.h"
+#ifdef USE_API_NOISE
+// Only present in the build when the noise component is loaded
+#include "esphome/components/noise/noise.h"
+#endif
 #include "api_pb2.h"
 #include "api_pb2_service.h"
 #include "esphome/components/socket/socket.h"
@@ -37,7 +40,7 @@ class UserServiceDescriptor;
 
 #ifdef USE_API_NOISE
 struct SavedNoisePsk {
-  psk_t psk;
+  noise::psk_t psk;
 } PACKED;  // NOLINT
 #endif
 
@@ -73,10 +76,10 @@ class APIServer final : public Component,
   APIBuffer &get_shared_buffer_ref() { return shared_write_buffer_; }
 
 #ifdef USE_API_NOISE
-  bool save_noise_psk(psk_t psk, bool make_active = true);
+  bool save_noise_psk(noise::psk_t psk, bool make_active = true);
   bool clear_noise_psk(bool make_active = true);
-  void set_noise_psk(psk_t psk) { this->noise_ctx_.set_psk(psk); }
-  APINoiseContext &get_noise_ctx() { return this->noise_ctx_; }
+  void set_noise_psk(noise::psk_t psk) { this->noise_ctx_.set_psk(psk); }
+  noise::NoiseContext &get_noise_ctx() { return this->noise_ctx_; }
 #endif  // USE_API_NOISE
 
   void handle_disconnect(APIConnection *conn);
@@ -354,7 +357,7 @@ class APIServer final : public Component,
 #endif
 
 #ifdef USE_API_NOISE
-  APINoiseContext noise_ctx_;
+  noise::NoiseContext noise_ctx_;
   ESPPreferenceObject noise_pref_;
 #endif  // USE_API_NOISE
 };

esphome/components/api/list_entities.cpp

@@ -95,9 +95,17 @@ bool ListEntitiesIterator::on_end() { return this->client_->send_list_info_done(
 ListEntitiesIterator::ListEntitiesIterator(APIConnection *client) : client_(client) {}
 
 #ifdef USE_API_USER_DEFINED_ACTIONS
+// Yield after every Nth service; bounds direct (non-batched) writes per loop pass
+static constexpr uint8_t SERVICE_YIELD_INTERVAL = 3;
+
 bool ListEntitiesIterator::on_service(UserServiceDescriptor *service) {
   auto resp = service->encode_list_service_response();
-  return this->client_->send_message(resp);
+  if (!this->client_->send_message(resp))
+    return false;
+  // at_ is this service's index
+  if ((this->at_ + 1) % SERVICE_YIELD_INTERVAL == 0)
+    this->yield_after_step_();
+  return true;
 }
 #endif
 

esphome/components/api/proto.h

@@ -684,11 +684,6 @@ class ProtoSize {
     return value < VARINT_THRESHOLD_1_BYTE ? 1 : (value < VARINT_THRESHOLD_2_BYTE ? 2 : 3);
   }
 
-  // Varint encoded length for an 8-bit value (1 or 2 bytes).
-  static constexpr inline uint8_t ESPHOME_ALWAYS_INLINE varint8(uint8_t value) {
-    return value < VARINT_THRESHOLD_1_BYTE ? 1 : 2;
-  }
-
   /**
    * @brief Calculates the size in bytes needed to encode a uint32_t value as a varint
    *

esphome/components/aqi/sensor.py

@@ -7,6 +7,7 @@ from esphome.const import (
     DEVICE_CLASS_AQI,
     STATE_CLASS_MEASUREMENT,
 )
+from esphome.types import ConfigType
 
 from . import AQI_CALCULATION_TYPE, CONF_CALCULATION_TYPE, CONF_EXTENDED_RANGE, aqi_ns
 
@@ -16,7 +17,7 @@ DEPENDENCIES = ["sensor"]
 AQISensor = aqi_ns.class_("AQISensor", sensor.Sensor, cg.Component)
 
 
-def _validate_extended_range(config):
+def _validate_extended_range(config: ConfigType) -> ConfigType:
     if CONF_EXTENDED_RANGE in config and config[CONF_CALCULATION_TYPE] == "CAQI":
         raise cv.Invalid(
             f"'{CONF_EXTENDED_RANGE}' is not supported with 'calculation_type: CAQI'. "
@@ -48,7 +49,7 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await sensor.new_sensor(config)
     await cg.register_component(var, config)
 

esphome/components/as3935_i2c/__init__.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import as3935, i2c
 import esphome.config_validation as cv
 from esphome.const import CONF_ID
+from esphome.types import ConfigType
 
 AUTO_LOAD = ["as3935"]
 DEPENDENCIES = ["i2c"]
@@ -20,7 +21,7 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await as3935.setup_as3935(var, config)
     await i2c.register_i2c_device(var, config)

esphome/components/as3935_spi/__init__.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import as3935, spi
 import esphome.config_validation as cv
 from esphome.const import CONF_ID
+from esphome.types import ConfigType
 
 AUTO_LOAD = ["as3935"]
 DEPENDENCIES = ["spi"]
@@ -20,7 +21,7 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await as3935.setup_as3935(var, config)
     await spi.register_spi_device(var, config)

esphome/components/as7341/sensor.py

@@ -9,6 +9,7 @@ from esphome.const import (
     ICON_BRIGHTNESS_5,
     STATE_CLASS_MEASUREMENT,
 )
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@mrgnr"]
 DEPENDENCIES = ["i2c"]
@@ -96,7 +97,7 @@ SENSORS = {
 }
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await i2c.register_i2c_device(var, config)

esphome/components/async_tcp/__init__.py

@@ -2,6 +2,7 @@
 import esphome.codegen as cg
 import esphome.config_validation as cv
 from esphome.core import CORE, CoroPriority, coroutine_with_priority
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@esphome/core"]
 DEPENDENCIES = ["network"]
@@ -25,7 +26,7 @@ CONFIG_SCHEMA = cv.Schema({})
 
 
 @coroutine_with_priority(CoroPriority.NETWORK_TRANSPORT)
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     if CORE.is_esp32:
         # https://github.com/ESP32Async/AsyncTCP
         from esphome.components.esp32 import add_idf_component

esphome/components/atc_mithermometer/sensor.py

@@ -21,6 +21,7 @@ from esphome.const import (
     UNIT_PERCENT,
     UNIT_VOLT,
 )
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@ahpohl"]
 
@@ -77,7 +78,7 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await ble_device_base.register_ble_device(var, config)

esphome/components/atm90e26/sensor.py

@@ -30,6 +30,7 @@ from esphome.const import (
     UNIT_WATT,
     UNIT_WATT_HOURS,
 )
+from esphome.types import ConfigType
 
 CONF_METER_CONSTANT = "meter_constant"
 CONF_PL_CONST = "pl_const"
@@ -123,7 +124,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await spi.register_spi_device(var, config)

esphome/components/audio/__init__.py

@@ -7,6 +7,7 @@ from esphome.components.esp32 import (
     add_idf_component,
     add_idf_sdkconfig_option,
     include_builtin_idf_component,
+    require_certificate_bundle,
 )
 import esphome.config_validation as cv
 from esphome.const import (
@@ -335,6 +336,8 @@ def _emit_memory_pair(value: str | None, psram_key: str, internal_key: str) -> N
 async def to_code(config: ConfigType) -> None:
     # Re-enable ESP-IDF's HTTP client (excluded by default to save compile time)
     include_builtin_idf_component("esp_http_client")
+    # HTTPS streams verify the server against the root certificate bundle
+    require_certificate_bundle()
 
     add_idf_component(
         name="esphome/esp-audio-libs",

esphome/components/audio_http/audio_http_media_source.cpp

@@ -30,8 +30,9 @@ void AudioHTTPMediaSource::dump_config() {
   ESP_LOGCONFIG(TAG,
                 "Audio HTTP Media Source:\n"
                 "  Buffer Size: %zu bytes\n"
+                "  Persistent Ring Buffer: %s\n"
                 "  Decoder Task Stack in PSRAM: %s",
-                this->buffer_size_, YESNO(this->decoder_task_stack_in_psram_));
+                this->buffer_size_, YESNO(this->persistent_ring_buffer_), YESNO(this->decoder_task_stack_in_psram_));
 }
 
 void AudioHTTPMediaSource::setup() {
@@ -39,6 +40,7 @@ void AudioHTTPMediaSource::setup() {
 
   micro_decoder::DecoderConfig config;
   config.ring_buffer_size = this->buffer_size_;
+  config.persistent_ring_buffer = this->persistent_ring_buffer_;
   // Keep the transfer buffer smaller than the ring buffer so the reader can top up the ring
   // while the decoder is still draining it, instead of oscillating between empty and full.
   config.transfer_buffer_size = std::min(DEFAULT_TRANSFER_BUFFER_SIZE, this->buffer_size_ / 2);

esphome/components/audio_http/audio_http_media_source.h

@@ -33,6 +33,7 @@ class AudioHTTPMediaSource final : public Component,
 
   void set_buffer_size(size_t buffer_size) { this->buffer_size_ = buffer_size; }
   void set_task_stack_in_psram(bool task_stack_in_psram) { this->decoder_task_stack_in_psram_ = task_stack_in_psram; }
+  void set_persistent_ring_buffer(bool persistent) { this->persistent_ring_buffer_ = persistent; }
 
   // MediaSource interface implementation
   bool play_uri(const std::string &uri) override;
@@ -54,6 +55,7 @@ class AudioHTTPMediaSource final : public Component,
   // on_audio_write(). Must be atomic to avoid a data race.
   std::atomic<bool> pause_{false};
   bool decoder_task_stack_in_psram_{false};
+  bool persistent_ring_buffer_{false};
 };
 
 }  // namespace esphome::audio_http

esphome/components/audio_http/media_source.py

@@ -7,6 +7,8 @@ from esphome.types import ConfigType
 CODEOWNERS = ["@kahrendt"]
 AUTO_LOAD = ["audio"]
 
+CONF_PERSISTENT_RING_BUFFER = "persistent_ring_buffer"
+
 audio_http_ns = cg.esphome_ns.namespace("audio_http")
 AudioHTTPMediaSource = audio_http_ns.class_(
     "AudioHTTPMediaSource", cg.Component, media_source.MediaSource
@@ -28,6 +30,7 @@ CONFIG_SCHEMA = cv.All(
                 min=5000, max=1000000
             ),
             cv.Optional(CONF_TASK_STACK_IN_PSRAM): psram.validate_task_stack_in_psram,
+            cv.Optional(CONF_PERSISTENT_RING_BUFFER, default=False): cv.boolean,
         }
     )
     .extend(cv.COMPONENT_SCHEMA),
@@ -45,3 +48,4 @@ async def to_code(config: ConfigType) -> None:
         cg.add(var.set_task_stack_in_psram(True))
         psram.request_external_task_stack()
     cg.add(var.set_buffer_size(config[CONF_BUFFER_SIZE]))
+    cg.add(var.set_persistent_ring_buffer(config[CONF_PERSISTENT_RING_BUFFER]))

esphome/components/axs15231/touchscreen/__init__.py

@@ -3,6 +3,7 @@ import esphome.codegen as cg
 from esphome.components import i2c, touchscreen
 import esphome.config_validation as cv
 from esphome.const import CONF_ID, CONF_INTERRUPT_PIN, CONF_RESET_PIN
+from esphome.types import ConfigType
 
 from .. import axs15231_ns
 
@@ -25,7 +26,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await touchscreen.register_touchscreen(var, config)
     await i2c.register_i2c_device(var, config)

esphome/components/b_parasite/sensor.py

@@ -20,6 +20,7 @@ from esphome.const import (
     UNIT_PERCENT,
     UNIT_VOLT,
 )
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@rbaron"]
 
@@ -74,7 +75,7 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await ble_device_base.register_ble_device(var, config)

esphome/components/ballu/climate.py

@@ -1,5 +1,6 @@
 import esphome.codegen as cg
 from esphome.components import climate_ir
+from esphome.types import ConfigType
 
 AUTO_LOAD = ["climate_ir"]
 CODEOWNERS = ["@bazuchan"]
@@ -10,5 +11,5 @@ BalluClimate = ballu_ns.class_("BalluClimate", climate_ir.ClimateIR)
 CONFIG_SCHEMA = climate_ir.climate_ir_with_receiver_schema(BalluClimate)
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     await climate_ir.new_climate_ir(config)

esphome/components/bang_bang/climate.py

@@ -12,6 +12,7 @@ from esphome.const import (
     CONF_IDLE_ACTION,
     CONF_SENSOR,
 )
+from esphome.types import ConfigType
 
 bang_bang_ns = cg.esphome_ns.namespace("bang_bang")
 BangBangClimate = bang_bang_ns.class_("BangBangClimate", climate.Climate, cg.Component)
@@ -41,7 +42,7 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await climate.new_climate(config)
     await cg.register_component(var, config)
 

esphome/components/beken_spi_led_strip/light.py

@@ -56,7 +56,7 @@ SUPPORTED_PINS = {
 }
 
 
-def _validate_pin(value):
+def _validate_pin(value: int) -> int:
     family = libretiny.get_libretiny_family()
     if family not in SUPPORTED_PINS:
         raise cv.Invalid(f"Chip family {family} is not supported.")

esphome/components/bh1750/sensor.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import i2c, sensor
 import esphome.config_validation as cv
 from esphome.const import DEVICE_CLASS_ILLUMINANCE, STATE_CLASS_MEASUREMENT, UNIT_LUX
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["i2c"]
 CODEOWNERS = ["@OttoWinter"]
@@ -25,7 +26,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await sensor.new_sensor(config)
     await cg.register_component(var, config)
     await i2c.register_i2c_device(var, config)

esphome/components/bh1900nux/sensor.py

@@ -6,6 +6,7 @@ from esphome.const import (
     STATE_CLASS_MEASUREMENT,
     UNIT_CELSIUS,
 )
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["i2c"]
 CODEOWNERS = ["@B48D81EFCC"]
@@ -28,7 +29,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await sensor.new_sensor(config)
     await cg.register_component(var, config)
     await i2c.register_i2c_device(var, config)

esphome/components/binary/fan/__init__.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import fan, output
 import esphome.config_validation as cv
 from esphome.const import CONF_DIRECTION_OUTPUT, CONF_OSCILLATION_OUTPUT, CONF_OUTPUT
+from esphome.types import ConfigType
 
 from .. import binary_ns
 
@@ -20,7 +21,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await fan.new_fan(config)
     await cg.register_component(var, config)
 

esphome/components/binary/light/__init__.py

@@ -2,6 +2,7 @@ import esphome.codegen as cg
 from esphome.components import light, output
 import esphome.config_validation as cv
 from esphome.const import CONF_OUTPUT, CONF_OUTPUT_ID
+from esphome.types import ConfigType
 
 from .. import binary_ns
 
@@ -15,7 +16,7 @@ CONFIG_SCHEMA = light.BINARY_LIGHT_SCHEMA.extend(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_OUTPUT_ID])
     await light.register_light(var, config)
 

esphome/components/binary_sensor/__init__.py

@@ -5,6 +5,7 @@ from esphome.automation import Condition, maybe_simple_id
 import esphome.codegen as cg
 from esphome.components import mqtt, web_server, zigbee
 from esphome.components.const import CONF_ON_STATE_CHANGE
+from esphome.config_helpers import filter_source_files_from_defines
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_DELAY,
@@ -560,6 +561,11 @@ _CALLBACK_AUTOMATIONS = (
 async def _build_binary_sensor_automations(var, config):
     await automation.build_callback_automations(var, config, _CALLBACK_AUTOMATIONS)
 
+    if config.get(CONF_ON_CLICK) or config.get(CONF_ON_DOUBLE_CLICK):
+        cg.add_define("USE_BINARY_SENSOR_CLICK_TRIGGER")
+    if config.get(CONF_ON_MULTI_CLICK):
+        cg.add_define("USE_BINARY_SENSOR_MULTI_CLICK_TRIGGER")
+
     for conf in config.get(CONF_ON_CLICK, []):
         trigger = cg.new_Pvariable(
             conf[CONF_TRIGGER_ID], var, conf[CONF_MIN_LENGTH], conf[CONF_MAX_LENGTH]
@@ -673,3 +679,15 @@ async def to_code(config):
 async def binary_sensor_invalidate_state_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
     return cg.new_Pvariable(action_id, template_arg, paren)
+
+
+# automation.cpp only implements the click/double_click/multi_click triggers
+FILTER_SOURCE_FILES = filter_source_files_from_defines(
+    {
+        "automation.cpp": (
+            "USE_BINARY_SENSOR_CLICK_TRIGGER",
+            "USE_BINARY_SENSOR_MULTI_CLICK_TRIGGER",
+        ),
+        "filter.cpp": "USE_BINARY_SENSOR_FILTER",
+    }
+)

esphome/components/binary_sensor/automation.cpp

@@ -1,8 +1,13 @@
+#include "esphome/core/defines.h"
+#if defined(USE_BINARY_SENSOR_CLICK_TRIGGER) || defined(USE_BINARY_SENSOR_MULTI_CLICK_TRIGGER)
+
 #include "automation.h"
 #include "esphome/core/log.h"
 
 namespace esphome::binary_sensor {
 
+#ifdef USE_BINARY_SENSOR_MULTI_CLICK_TRIGGER
+
 static const char *const TAG = "binary_sensor.automation";
 
 // MultiClickTrigger timeout IDs.
@@ -120,6 +125,9 @@ void MultiClickTriggerBase::trigger_() {
   this->trigger();
 }
 
+#endif  // USE_BINARY_SENSOR_MULTI_CLICK_TRIGGER
+
+#ifdef USE_BINARY_SENSOR_CLICK_TRIGGER
 bool match_interval(uint32_t min_length, uint32_t max_length, uint32_t length) {
   if (max_length == 0) {
     return length >= min_length;
@@ -127,4 +135,8 @@ bool match_interval(uint32_t min_length, uint32_t max_length, uint32_t length) {
     return length >= min_length && length <= max_length;
   }
 }
+#endif  // USE_BINARY_SENSOR_CLICK_TRIGGER
+
 }  // namespace esphome::binary_sensor
+
+#endif  // USE_BINARY_SENSOR_CLICK_TRIGGER || USE_BINARY_SENSOR_MULTI_CLICK_TRIGGER

esphome/components/binary_sensor_map/sensor.py

@@ -10,6 +10,7 @@ from esphome.const import (
     CONF_VALUE,
     ICON_CHECK_CIRCLE_OUTLINE,
 )
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["binary_sensor"]
 
@@ -82,7 +83,7 @@ CONFIG_SCHEMA = cv.typed_schema(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await sensor.new_sensor(config)
     await cg.register_component(var, config)
 

esphome/components/bk72xx/__init__.py

@@ -28,6 +28,8 @@ from esphome.components.libretiny.const import (
     LibreTinyComponent,
 )
 from esphome.core import CORE
+from esphome.cpp_generator import MockObj
+from esphome.types import ConfigType
 
 from .boards import BK72XX_BOARD_PINS, BK72XX_BOARDS
 
@@ -45,7 +47,7 @@ COMPONENT_DATA = LibreTinyComponent(
 )
 
 
-def _set_core_data(config):
+def _set_core_data(config: ConfigType) -> ConfigType:
     CORE.data[KEY_LIBRETINY] = {}
     CORE.data[KEY_LIBRETINY][KEY_COMPONENT_DATA] = COMPONENT_DATA
     return config
@@ -62,12 +64,12 @@ PIN_SCHEMA = libretiny.gpio.BASE_PIN_SCHEMA
 CONFIG_SCHEMA.prepend_extra(_set_core_data)
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> MockObj:
     return await libretiny.component_to_code(config)
 
 
 @pins.PIN_SCHEMA_REGISTRY.register("bk72xx", PIN_SCHEMA)
-async def pin_to_code(config):
+async def pin_to_code(config: ConfigType) -> MockObj:
     return await libretiny.gpio.component_pin_to_code(config)
 
 

esphome/components/bl0939/sensor.py

@@ -15,6 +15,7 @@ from esphome.const import (
     UNIT_VOLT,
     UNIT_WATT,
 )
+from esphome.types import ConfigType
 
 DEPENDENCIES = ["uart"]
 
@@ -88,7 +89,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await uart.register_uart_device(var, config)

esphome/components/bl0942/sensor.py

@@ -24,6 +24,7 @@ from esphome.const import (
     UNIT_VOLT,
     UNIT_WATT,
 )
+from esphome.types import ConfigType
 
 CONF_CURRENT_REFERENCE = "current_reference"
 CONF_ENERGY_REFERENCE = "energy_reference"
@@ -95,7 +96,7 @@ CONFIG_SCHEMA = (
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await uart.register_uart_device(var, config)

esphome/components/ble_device_base/__init__.py

@@ -206,32 +206,36 @@ def validate_scan_parameters(config: ConfigType) -> ConfigType:
     interval = config[CONF_INTERVAL]
     window = config[CONF_WINDOW]
 
-    if window > interval:
-        raise cv.Invalid(
-            f"Scan window ({window}) needs to be smaller than scan interval ({interval})"
-        )
+    # Labels are reused in every error below; the optional one names its key.
+    windows = [("Scan window", window)]
+    if (connection_window := config.get(CONF_CONNECTION_SCAN_WINDOW)) is not None:
+        windows.append((CONF_CONNECTION_SCAN_WINDOW, connection_window))
+
+    for name, value in windows:
+        if value > interval:
+            raise cv.Invalid(
+                f"{name} ({value}) needs to be smaller than scan interval ({interval})"
+            )
 
     # BLE scan interval/window are programmed in 0.625 ms units as a 16-bit value; the
     # controller only accepts 2.5 ms .. 10240 ms (0x0004 .. 0x4000). Reject out-of-range
     # values here instead of letting the unit conversion silently overflow.
-    for name, value in (("interval", interval), ("window", window)):
+    for name, value in (("Scan interval", interval), *windows):
         if value.total_microseconds < 2500 or value.total_microseconds > 10_240_000:
-            raise cv.Invalid(
-                f"Scan {name} ({value}) must be between 2.5 ms and 10240 ms"
-            )
+            raise cv.Invalid(f"{name} ({value}) must be between 2.5 ms and 10240 ms")
 
     # Validate what actually reaches the controller: both values are truncated to
     # whole 0.625 ms units, so a window/interval pair that differs by less than one
     # unit collapses to the same value — silently programming a 100 % duty cycle
     # (radio permanently on) from a config that asked for less.
     interval_units = to_ble_units(interval)
-    window_units = to_ble_units(window)
-    if window_units == interval_units and window < interval:
-        raise cv.Invalid(
-            f"Scan window ({window}) and interval ({interval}) both truncate to "
-            f"{interval_units} x 0.625 ms, which the controller scans at a 100 % duty "
-            f"cycle. Separate them by at least 0.625 ms."
-        )
+    for name, value in windows:
+        if to_ble_units(value) == interval_units and value < interval:
+            raise cv.Invalid(
+                f"{name} ({value}) and interval ({interval}) both truncate to "
+                f"{interval_units} x 0.625 ms, which the controller scans at a 100 % duty "
+                f"cycle. Separate them by at least 0.625 ms."
+            )
 
     if interval.total_microseconds * 3 > duration.total_microseconds:
         raise cv.Invalid(
@@ -247,11 +251,14 @@ def validate_scan_parameters(config: ConfigType) -> ConfigType:
 # their own; also the fallback for esp32's conditional default.
 DEFAULT_SCAN_WINDOW = "30ms"
 
+CONF_CONNECTION_SCAN_WINDOW = "connection_scan_window"
+
 
 def scan_parameters_schema(
     interval_default: str,
     *,
     window_default: str | Callable[[], TimePeriod] = DEFAULT_SCAN_WINDOW,
+    connection_window: bool = False,
 ) -> cv.All:
     """Build the scan_parameters value schema shared by all BLE trackers.
 
@@ -263,7 +270,9 @@ def scan_parameters_schema(
     can adjust it once sibling keys are resolved). The `active` option
     (default on) is unconditional: active scanning is part of the tracker
     contract — every current proxy client assumes it, so a passive-only
-    tracker must not share this schema.
+    tracker must not share this schema. connection_window opts in to the
+    `connection_scan_window` option for trackers that can fall back to a
+    smaller window while a GATT connection is active.
     """
     schema = {
         cv.Optional(CONF_DURATION, default="5min"): cv.positive_time_period_seconds,
@@ -272,6 +281,8 @@ def scan_parameters_schema(
         cv.Optional(CONF_CONTINUOUS, default=True): cv.boolean,
         cv.Optional(CONF_ACTIVE, default=True): cv.boolean,
     }
+    if connection_window:
+        schema[cv.Optional(CONF_CONNECTION_SCAN_WINDOW)] = cv.positive_time_period
     return cv.All(cv.Schema(schema), validate_scan_parameters)
 
 

esphome/components/ble_device_base/automation.py

@@ -1,5 +1,6 @@
 """Shared codegen for the neutral BLE advertisement triggers (automation.h)."""
 
+from collections.abc import Callable
 from typing import Any
 
 from esphome import automation
@@ -52,7 +53,7 @@ _UUID_WIDTHS = {
 
 def uuid_trigger_schema(
     trigger_class: MockObjClass, extra: dict[Any, Any] | None = None
-):
+) -> Callable[[Any], Any]:
     """Schema for a UUID-filtered trigger — pairs with uuid_trigger_to_code().
 
     `extra` carries the required UUID key (a cv marker, so a dict rather than
@@ -68,7 +69,7 @@ def uuid_trigger_schema(
     )
 
 
-def advertise_trigger_schema(trigger_class: MockObjClass):
+def advertise_trigger_schema(trigger_class: MockObjClass) -> Callable[[Any], Any]:
     """on_ble_advertise schema: multi-mac list filter, unlike the single-mac
     uuid_trigger_schema() — pairs with advertise_trigger_to_code()."""
     return automation.validate_automation(
@@ -79,7 +80,7 @@ def advertise_trigger_schema(trigger_class: MockObjClass):
     )
 
 
-def scan_end_trigger_schema(trigger_class: MockObjClass):
+def scan_end_trigger_schema(trigger_class: MockObjClass) -> Callable[[Any], Any]:
     """on_scan_end schema: id only — pairs with scan_end_trigger_to_code()."""
     return automation.validate_automation(
         {cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(trigger_class)}

esphome/components/ble_presence/binary_sensor.py

@@ -10,6 +10,7 @@ from esphome.const import (
     CONF_SERVICE_UUID,
     CONF_TIMEOUT,
 )
+from esphome.types import ConfigType
 
 CONF_IRK = "irk"
 
@@ -24,7 +25,7 @@ BLEPresenceDevice = ble_presence_ns.class_(
 )
 
 
-def _validate(config):
+def _validate(config: ConfigType) -> ConfigType:
     if CONF_IBEACON_MAJOR in config and CONF_IBEACON_UUID not in config:
         raise cv.Invalid("iBeacon major identifier requires iBeacon UUID")
     if CONF_IBEACON_MINOR in config and CONF_IBEACON_UUID not in config:
@@ -58,7 +59,7 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = await binary_sensor.new_binary_sensor(config)
     await cg.register_component(var, config)
     await ble_device_base.register_ble_device(var, config)