[web_server] Match the blank page remedy to the actual cause

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Co-authored-by: J. Nick Koston <nick@koston.org>

.github/actions/restore-python/action.yml

@@ -49,7 +49,7 @@ runs:
         python -m venv venv
         source venv/bin/activate
         python --version
-        uv pip install -r requirements.txt -r requirements_test.txt
+        uv pip install -r requirements.txt -r requirements_dev.txt -r requirements_test.txt
         uv pip install -e .
     - name: Create Python virtual environment
       if: steps.cache-venv.outputs.cache-hit != 'true' && runner.os == 'Windows'
@@ -58,5 +58,5 @@ runs:
         python -m venv venv
         source ./venv/Scripts/activate
         python --version
-        uv pip install -r requirements.txt -r requirements_test.txt
+        uv pip install -r requirements.txt -r requirements_dev.txt -r requirements_test.txt
         uv pip install -e .

.github/workflows/ci-api-proto.yml

@@ -41,10 +41,32 @@ jobs:
           version: "0.11.15"
 
       - name: Install apt dependencies
+        # PR-only workflow, so nothing on dev could seed a shared apt cache
+        # entry; the cached apt action would save one copy per PR. Plain apt
+        # with every call bounded: the apt.conf.d timeouts make a dead
+        # mirror fail over in seconds, and timeout runs under sudo so it can
+        # kill apt-get itself. Install without update first: image lists are
+        # fresh, and the index refresh is what a congested mirror makes slow.
+        timeout-minutes: 15
         run: |
-          sudo apt update
-          sudo apt-cache show protobuf-compiler
-          sudo apt install -y protobuf-compiler
+          sudo tee /etc/apt/apt.conf.d/99ci-acquire-timeouts >/dev/null <<'EOF'
+          Acquire::Retries "1";
+          Acquire::http::Timeout "15";
+          Acquire::https::Timeout "15";
+          EOF
+          # Common path: the image's package lists are fresh enough.
+          if sudo DEBIAN_FRONTEND=noninteractive timeout -k 15 90 \
+              apt-get install -y protobuf-compiler; then
+            protoc --version
+            exit 0
+          fi
+          # Rescue path: refresh the lists once with a generous bound; the
+          # apt config already fails a stalled mirror over quickly.
+          sudo DEBIAN_FRONTEND=noninteractive timeout -k 10 30 \
+            dpkg --configure -a || true
+          sudo timeout -k 15 300 apt-get update
+          sudo DEBIAN_FRONTEND=noninteractive timeout -k 15 300 \
+            apt-get install -y protobuf-compiler
           protoc --version
       - name: Install python dependencies
         run: uv pip install --system aioesphomeapi -c requirements.txt -r requirements_dev.txt

.github/workflows/ci.yml

@@ -68,6 +68,22 @@ jobs:
           uv pip install -r requirements.txt -r requirements_dev.txt -r requirements_test.txt
           uv pip install -e .
 
+  seed-apt-cache:
+    name: Seed apt package cache
+    runs-on: ubuntu-24.04
+    # PR-branch cache saves are invisible to other PRs, so dev/beta/release
+    # pushes seed the one shared entry PR jobs restore. The key is derived
+    # only from the package list and version; keep both identical in every
+    # step that restores it. In ci-status needs so a broken seed fails dev.
+    if: github.event_name == 'push'
+    timeout-minutes: 10
+    steps:
+      - name: Install apt packages (cached)
+        uses: awalsh128/cache-apt-pkgs-action@553a35bb8ebd9fcabcb1c9451aa4c98e1b4ca8a9 # v1.6.3
+        with:
+          packages: libsdl2-dev ccache
+          version: 1.1
+
   determine-jobs:
     name: Determine which jobs to run
     runs-on: ubuntu-24.04
@@ -323,7 +339,8 @@ jobs:
 
   integration-tests:
     name: Run integration tests (${{ matrix.bucket.name }})
-    runs-on: ubuntu-latest
+    # Must match seed-apt-cache's image: the apt cache key has no OS in it.
+    runs-on: ubuntu-24.04
     needs:
       - common
       - determine-jobs
@@ -335,24 +352,16 @@ jobs:
     steps:
       - name: Check out code from GitHub
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
-      - name: Install ccache
-        # Speeds up the host compiles: tests in a bucket compile overlapping
-        # component sets, so later tests reuse earlier tests' objects.
-        run: |
-          sudo apt-get update -qq
-          sudo apt-get install -y --no-install-recommends ccache
-      - name: Restore ccache (restore-only)
-        # esphome stores the PlatformIO ccache under the machine-global cache
-        # dir (see _ccache_env() in esphome/platformio/toolchain.py). The
-        # bucket-name prefix prefers a same-bucket seed; the bare prefix falls
-        # back to any seed when the bucket layout differs from dev.
-        uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+      - name: Install apt packages (cached)
+        # ccache speeds up the host compiles. A cache hit never touches apt
+        # (mirror outages cannot hang the job); the timeout bounds the cold
+        # path. Packages and version must match seed-apt-cache exactly;
+        # libsdl2-dev is unused here and carried only for cache-key parity.
+        timeout-minutes: 10
+        uses: awalsh128/cache-apt-pkgs-action@553a35bb8ebd9fcabcb1c9451aa4c98e1b4ca8a9 # v1.6.3
         with:
-          path: ~/.cache/esphome/platformio-ccache
-          key: integration-ccache-${{ matrix.bucket.name }}-${{ github.sha }}
-          restore-keys: |
-            integration-ccache-${{ matrix.bucket.name }}-
-            integration-ccache-
+          packages: libsdl2-dev ccache
+          version: 1.1
       - name: Set up Python 3.13
         id: python
         uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
@@ -401,14 +410,6 @@ jobs:
         # esphome stores the PlatformIO ccache under the machine-global cache
         # dir (see _ccache_env() in esphome/platformio/toolchain.py).
         run: CCACHE_DIR="$HOME/.cache/esphome/platformio-ccache" ccache -s
-      - name: Save ccache
-        # Pull request saves land in per-PR scopes nothing else can reuse;
-        # dev pushes seed the shared copy instead.
-        if: github.event_name != 'pull_request'
-        uses: actions/cache/save@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
-        with:
-          path: ~/.cache/esphome/platformio-ccache
-          key: integration-ccache-${{ matrix.bucket.name }}-${{ github.sha }}
 
   import-time:
     name: Check import esphome.__main__ time
@@ -441,6 +442,7 @@ jobs:
   benchmarks:
     name: Run CodSpeed benchmarks
     runs-on: ubuntu-24.04
+    timeout-minutes: 30
     needs:
       - common
       - determine-jobs
@@ -464,12 +466,58 @@ jobs:
       - name: Build benchmarks
         id: build
         run: |
+          # pipefail: without it a failed build is masked by the grep/cut
+          # pipeline below, leaving BINARY empty and silently dropping every
+          # C++ benchmark from the run while the job still reports success.
+          set -o pipefail
           . venv/bin/activate
-          export BENCHMARK_LIB_CONFIG=$(python script/setup_codspeed_lib.py)
-          # --build-only prints BUILD_BINARY=<path> to stdout
-          BINARY=$(script/cpp_benchmark.py --all --build-only | grep '^BUILD_BINARY=' | tail -1 | cut -d= -f2-)
+          BENCHMARK_LIB_CONFIG=$(python script/setup_codspeed_lib.py)
+          export BENCHMARK_LIB_CONFIG
+          # --build-only prints BUILD_BINARY=<path> to stdout; the grep is
+          # non-fatal so a missing marker reaches the check below instead of
+          # tripping errexit at this assignment
+          BINARY=$(script/cpp_benchmark.py --all --build-only | { grep '^BUILD_BINARY=' || true; } | tail -1 | cut -d= -f2-)
+          if [ -z "$BINARY" ]; then
+            echo "::error::Benchmark build did not report a binary path"
+            exit 1
+          fi
           echo "binary=$BINARY" >> $GITHUB_OUTPUT
 
+      - name: Bound apt fetches and pre-install libc6-dbg
+        # The CodSpeed runner installs valgrind + libc6-dbg via its own
+        # unbounded apt-get update; per-invocation apt options cannot reach
+        # it. The apt.conf.d timeouts below bound every later apt call in
+        # this job, the runner's included. Pre-installing libc6-dbg lets the
+        # runner skip apt once its valgrind cache is restored (it checks
+        # ``dpkg -s libc6-dbg``, so the cache action's unregistered restores
+        # would not count). Install without update first: image lists are
+        # fresh, and the index refresh is what a congested mirror makes
+        # slow. Best effort; the job timeout is the last backstop.
+        timeout-minutes: 15
+        continue-on-error: true
+        run: |
+          sudo tee /etc/apt/apt.conf.d/99ci-acquire-timeouts >/dev/null <<'EOF'
+          Acquire::Retries "1";
+          Acquire::http::Timeout "15";
+          Acquire::https::Timeout "15";
+          EOF
+          if dpkg -s libc6-dbg >/dev/null 2>&1; then
+            echo "libc6-dbg already installed"
+            exit 0
+          fi
+          # Common path: the image's package lists are fresh enough.
+          if sudo DEBIAN_FRONTEND=noninteractive timeout -k 15 90 \
+              apt-get install -y libc6-dbg; then
+            exit 0
+          fi
+          # Rescue path: refresh the lists once with a generous bound; the
+          # apt config already fails a stalled mirror over quickly.
+          sudo DEBIAN_FRONTEND=noninteractive timeout -k 10 30 \
+            dpkg --configure -a || true
+          sudo timeout -k 15 300 apt-get update
+          sudo DEBIAN_FRONTEND=noninteractive timeout -k 15 300 \
+            apt-get install -y libc6-dbg
+
       - name: Run CodSpeed benchmarks
         uses: CodSpeedHQ/action@4296e51e7041e24dadb86d1d6e8b9320d223dbe8 # v5.0.3
         with:
@@ -554,24 +602,29 @@ jobs:
           fetch-depth: 2
 
       - name: Restore Python
+        id: restore-python
         uses: ./.github/actions/restore-python
         with:
           python-version: ${{ env.DEFAULT_PYTHON }}
           cache-key: ${{ needs.common.outputs.cache-key }}
 
+      # Key on the exact Python version as well: LibreTiny creates a venv under
+      # ~/.platformio/penv whose interpreter is a symlink into the runner's
+      # hosted toolcache, so a cache saved on an older runner image breaks once
+      # a new image ships a newer patch release and drops the old interpreter.
       - name: Cache platformio
         if: github.ref == 'refs/heads/dev' && matrix.pio_cache_key
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:
           path: ~/.platformio
-          key: platformio-${{ matrix.pio_cache_key }}-${{ hashFiles('platformio.ini') }}
+          key: platformio-${{ matrix.pio_cache_key }}-${{ steps.restore-python.outputs.python-version }}-${{ hashFiles('platformio.ini') }}
 
       - name: Cache platformio
         if: github.ref != 'refs/heads/dev' && matrix.pio_cache_key
         uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:
           path: ~/.platformio
-          key: platformio-${{ matrix.pio_cache_key }}-${{ hashFiles('platformio.ini') }}
+          key: platformio-${{ matrix.pio_cache_key }}-${{ steps.restore-python.outputs.python-version }}-${{ hashFiles('platformio.ini') }}
 
       - name: Cache ESP-IDF install
         if: matrix.cache_idf
@@ -888,12 +941,17 @@ jobs:
       - name: List components
         run: echo ${{ matrix.batch.components }}
 
-      - name: Install apt packages
-        # Not cached: this job is pull-request-only, so a cache save could
-        # never be shared and would only consume quota.
-        run: |
-          sudo apt-get update -qq
-          sudo apt-get install -y --no-install-recommends libsdl2-dev ccache
+      - name: Install apt packages (cached)
+        # A cache hit (seeded on dev by seed-apt-cache) never touches apt,
+        # so mirror outages cannot hang this PR-only job; the timeout bounds
+        # the cold path. Packages and version must match seed-apt-cache
+        # exactly. The action has no --no-install-recommends; same package
+        # set this job used before #17463.
+        timeout-minutes: 10
+        uses: awalsh128/cache-apt-pkgs-action@553a35bb8ebd9fcabcb1c9451aa4c98e1b4ca8a9 # v1.6.3
+        with:
+          packages: libsdl2-dev ccache
+          version: 1.1
 
       - name: Check out code from GitHub
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -1428,6 +1486,7 @@ jobs:
     # this check.
     needs:
       - common
+      - seed-apt-cache
       - determine-jobs
       - ci-custom
       - pylint

AGENTS.md

@@ -763,3 +763,13 @@ The project uses English for non-code content. When drafting documentation, code
 PR descriptions, and similar text, avoid technical jargon. Instead, express concepts in plain English,
 using standard technical terms only when required. Ensure the text is readily comprehensible to a wide
 audience, including non-native English speakers.
+
+## 10. Code Comments
+
+Code comments on individual lines should be used only where necessary to flag issues that may not be obvious
+on a simple reading of the code. Keep them short (e.g. 1 or 2 lines).
+
+Function and method comment blocks may include more detail as required to make
+calling contracts clear and document parameter usage, but should still be kept concise.
+
+Avoid redundancy and repetition; comments should never simply restate what the code already says.

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==1.11.0
+RUN uv pip install --no-cache-dir esphome-device-builder==1.12.0
 
 RUN \
     platformio settings set enable_telemetry No \

esphome/components/api/__init__.py

@@ -497,7 +497,7 @@ 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", "0.1.18")
+        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")

esphome/components/beken_spi_led_strip/led_strip.cpp

@@ -300,46 +300,12 @@ void BekenSPILEDStripLightOutput::write_state(light::LightState *state) {
 }
 
 light::ESPColorView BekenSPILEDStripLightOutput::get_view_internal(int32_t index) const {
-  int32_t r = 0, g = 0, b = 0;
-  switch (this->rgb_order_) {
-    case ORDER_RGB:
-      r = 0;
-      g = 1;
-      b = 2;
-      break;
-    case ORDER_RBG:
-      r = 0;
-      g = 2;
-      b = 1;
-      break;
-    case ORDER_GRB:
-      r = 1;
-      g = 0;
-      b = 2;
-      break;
-    case ORDER_GBR:
-      r = 2;
-      g = 0;
-      b = 1;
-      break;
-    case ORDER_BGR:
-      r = 2;
-      g = 1;
-      b = 0;
-      break;
-    case ORDER_BRG:
-      r = 1;
-      g = 2;
-      b = 0;
-      break;
-  }
-  uint8_t multiplier = this->is_rgbw_ || this->is_wrgb_ ? 4 : 3;
-  uint8_t white = this->is_wrgb_ ? 0 : 3;
-
-  return {this->buf_ + (index * multiplier) + r + this->is_wrgb_,
-          this->buf_ + (index * multiplier) + g + this->is_wrgb_,
-          this->buf_ + (index * multiplier) + b + this->is_wrgb_,
-          this->is_rgbw_ || this->is_wrgb_ ? this->buf_ + (index * multiplier) + white : nullptr,
+  const light::ChannelColors &colors = this->channel_colors_;
+  uint8_t *led = this->buf_ + (index * colors.bytes_per_led());
+  return {led + colors.r,
+          led + colors.g,
+          led + colors.b,
+          colors.has_white() ? led + colors.w : nullptr,
           &this->effect_data_[index],
           &this->correction_};
 }
@@ -349,35 +315,12 @@ void BekenSPILEDStripLightOutput::dump_config() {
                 "Beken SPI LED Strip:\n"
                 "  Pin: %u",
                 this->pin_);
-  const char *rgb_order;
-  switch (this->rgb_order_) {
-    case ORDER_RGB:
-      rgb_order = "RGB";
-      break;
-    case ORDER_RBG:
-      rgb_order = "RBG";
-      break;
-    case ORDER_GRB:
-      rgb_order = "GRB";
-      break;
-    case ORDER_GBR:
-      rgb_order = "GBR";
-      break;
-    case ORDER_BGR:
-      rgb_order = "BGR";
-      break;
-    case ORDER_BRG:
-      rgb_order = "BRG";
-      break;
-    default:
-      rgb_order = "UNKNOWN";
-      break;
-  }
+  char channel_colors[5];
   ESP_LOGCONFIG(TAG,
-                "  RGB Order: %s\n"
+                "  Channel colors: %s\n"
                 "  Max refresh rate: %" PRIu32 "\n"
                 "  Number of LEDs: %u",
-                rgb_order, this->max_refresh_rate_.value_or(0), this->num_leds_);
+                this->channel_colors_.to_string(channel_colors), this->max_refresh_rate_.value_or(0), this->num_leds_);
 }
 
 float BekenSPILEDStripLightOutput::get_setup_priority() const { return setup_priority::HARDWARE; }

esphome/components/beken_spi_led_strip/led_strip.h

@@ -3,6 +3,7 @@
 #ifdef USE_BK72XX
 
 #include "esphome/components/light/addressable_light.h"
+#include "esphome/components/light/channel_colors.h"
 #include "esphome/components/light/light_output.h"
 #include "esphome/core/color.h"
 #include "esphome/core/component.h"
@@ -10,15 +11,6 @@
 
 namespace esphome::beken_spi_led_strip {
 
-enum RGBOrder : uint8_t {
-  ORDER_RGB,
-  ORDER_RBG,
-  ORDER_GRB,
-  ORDER_GBR,
-  ORDER_BGR,
-  ORDER_BRG,
-};
-
 class BekenSPILEDStripLightOutput final : public light::AddressableLight {
  public:
   void setup() override;
@@ -28,7 +20,7 @@ class BekenSPILEDStripLightOutput final : public light::AddressableLight {
   int32_t size() const override { return this->num_leds_; }
   light::LightTraits get_traits() override {
     auto traits = light::LightTraits();
-    if (this->is_rgbw_ || this->is_wrgb_) {
+    if (this->channel_colors_.has_white()) {
       traits.set_supported_color_modes({light::ColorMode::RGB_WHITE, light::ColorMode::WHITE});
     } else {
       traits.set_supported_color_modes({light::ColorMode::RGB});
@@ -38,16 +30,13 @@ class BekenSPILEDStripLightOutput final : public light::AddressableLight {
 
   void set_pin(uint8_t pin) { this->pin_ = pin; }
   void set_num_leds(uint16_t num_leds) { this->num_leds_ = num_leds; }
-  void set_is_rgbw(bool is_rgbw) { this->is_rgbw_ = is_rgbw; }
-  void set_is_wrgb(bool is_wrgb) { this->is_wrgb_ = is_wrgb; }
+  void set_channel_colors(light::ChannelColors channel_colors) { this->channel_colors_ = channel_colors; }
 
   /// Set a maximum refresh rate in µs as some lights do not like being updated too often.
   void set_max_refresh_rate(uint32_t interval_us) { this->max_refresh_rate_ = interval_us; }
 
   void set_led_params(uint8_t bit0, uint8_t bit1, uint32_t spi_frequency);
 
-  void set_rgb_order(RGBOrder rgb_order) { this->rgb_order_ = rgb_order; }
-
   void clear_effect_data() override {
     for (int i = 0; i < this->size(); i++)
       this->effect_data_[i] = 0;
@@ -58,7 +47,7 @@ class BekenSPILEDStripLightOutput final : public light::AddressableLight {
  protected:
   light::ESPColorView get_view_internal(int32_t index) const override;
 
-  size_t get_buffer_size_() const { return this->num_leds_ * (this->is_rgbw_ || this->is_wrgb_ ? 4 : 3); }
+  size_t get_buffer_size_() const { return this->num_leds_ * this->channel_colors_.bytes_per_led(); }
 
   uint8_t *buf_{nullptr};
   uint8_t *effect_data_{nullptr};
@@ -66,13 +55,11 @@ class BekenSPILEDStripLightOutput final : public light::AddressableLight {
 
   uint8_t pin_;
   uint16_t num_leds_;
-  bool is_rgbw_;
-  bool is_wrgb_;
 
   uint32_t spi_frequency_{6666666};
   uint8_t bit0_{0xE0};
   uint8_t bit1_{0xFC};
-  RGBOrder rgb_order_;
+  light::ChannelColors channel_colors_{0, 1, 2, light::ChannelColors::NO_WHITE};
 
   uint32_t last_refresh_{0};
   optional<uint32_t> max_refresh_rate_{};

esphome/components/beken_spi_led_strip/light.py

@@ -3,6 +3,7 @@ from dataclasses import dataclass
 from esphome import pins
 import esphome.codegen as cg
 from esphome.components import libretiny, light
+from esphome.components.const import CONF_CHANNEL_COLORS, CONF_IS_WRGB
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_CHIPSET,
@@ -13,6 +14,7 @@ from esphome.const import (
     CONF_PIN,
     CONF_RGB_ORDER,
 )
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@Mat931"]
 DEPENDENCIES = ["libretiny"]
@@ -22,17 +24,6 @@ BekenSPILEDStripLightOutput = beken_spi_led_strip_ns.class_(
     "BekenSPILEDStripLightOutput", light.AddressableLight
 )
 
-RGBOrder = beken_spi_led_strip_ns.enum("RGBOrder")
-
-RGB_ORDERS = {
-    "RGB": RGBOrder.ORDER_RGB,
-    "RBG": RGBOrder.ORDER_RBG,
-    "GRB": RGBOrder.ORDER_GRB,
-    "GBR": RGBOrder.ORDER_GBR,
-    "BGR": RGBOrder.ORDER_BGR,
-    "BRG": RGBOrder.ORDER_BRG,
-}
-
 
 @dataclass
 class LEDStripTimings:
@@ -57,8 +48,6 @@ CHIPSETS = {
 }
 
 
-CONF_IS_WRGB = "is_wrgb"
-
 SUPPORTED_PINS = {
     libretiny.const.FAMILY_BK7231N: [16],
     libretiny.const.FAMILY_BK7231T: [16],
@@ -79,10 +68,9 @@ def _validate_pin(value):
     return value
 
 
-def _validate_num_leds(value):
-    max_num_leds = 165  # 170
-    if value[CONF_IS_RGBW] or value[CONF_IS_WRGB]:
-        max_num_leds = 123  # 127
+def _validate_num_leds(value: ConfigType) -> ConfigType:
+    # A white channel makes each LED one byte wider, so fewer of them fit in the DMA buffer.
+    max_num_leds = 123 if "W" in value[CONF_CHANNEL_COLORS] else 165  # 127 / 170
     if value[CONF_NUM_LEDS] > max_num_leds:
         raise cv.Invalid(
             f"The maximum number of LEDs for this configuration is {max_num_leds}.",
@@ -99,18 +87,23 @@ CONFIG_SCHEMA = cv.All(
                 pins.internal_gpio_output_pin_number, _validate_pin
             ),
             cv.Required(CONF_NUM_LEDS): cv.positive_not_null_int,
-            cv.Required(CONF_RGB_ORDER): cv.enum(RGB_ORDERS, upper=True),
+            cv.Optional(CONF_CHANNEL_COLORS): light.validate_channel_colors,
+            # Deprecated in favour of CONF_CHANNEL_COLORS, remove in 2027.3.0
+            cv.Optional(CONF_RGB_ORDER): cv.one_of(*light.RGB_ORDERS, upper=True),
+            cv.Optional(CONF_IS_RGBW): cv.boolean,
+            cv.Optional(CONF_IS_WRGB): cv.boolean,
             cv.Optional(CONF_MAX_REFRESH_RATE): cv.positive_time_period_microseconds,
             cv.Required(CONF_CHIPSET): cv.one_of(*CHIPSETS, upper=True),
-            cv.Optional(CONF_IS_RGBW, default=False): cv.boolean,
-            cv.Optional(CONF_IS_WRGB, default=False): cv.boolean,
         }
     ),
+    light.migrate_channel_colors(
+        removed_in="2027.3.0", component="beken_spi_led_strip"
+    ),
     _validate_num_leds,
 )
 
 
-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)
     await cg.register_component(var, config)
@@ -130,6 +123,6 @@ async def to_code(config):
         )
     )
 
-    cg.add(var.set_rgb_order(config[CONF_RGB_ORDER]))
-    cg.add(var.set_is_rgbw(config[CONF_IS_RGBW]))
-    cg.add(var.set_is_wrgb(config[CONF_IS_WRGB]))
+    cg.add(
+        var.set_channel_colors(light.channel_colors_struct(config[CONF_CHANNEL_COLORS]))
+    )

esphome/components/captive_portal/__init__.py

@@ -3,7 +3,6 @@ import logging
 import esphome.codegen as cg
 from esphome.components import web_server_base, wifi
 from esphome.components.web_server_base import CONF_WEB_SERVER_BASE_ID
-from esphome.config_helpers import filter_source_files_from_platform
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_AP,
@@ -15,7 +14,6 @@ from esphome.const import (
     PLATFORM_LN882X,
     PLATFORM_RP2,
     PLATFORM_RTL87XX,
-    PlatformFramework,
 )
 from esphome.core import CORE, coroutine_with_priority
 from esphome.coroutine import CoroPriority
@@ -76,17 +74,7 @@ def _final_validate(config: ConfigType) -> None:
             "Add 'ap:' to your WiFi configuration to enable the captive portal."
         )
 
-    # Register socket needs for DNS server and additional HTTP connections
-    # - 1 UDP socket for DNS server
-    # - 3 TCP sockets for captive portal detection probes + configuration requests
-    #   OS captive portal detection makes multiple probe requests that stay in TIME_WAIT.
-    #   Need headroom for actual user configuration requests.
-    #   LRU purging will reclaim idle sockets to prevent exhaustion from repeated attempts.
-    # The listening socket is registered by web_server_base (shared HTTP server).
-    from esphome.components import socket
-
-    socket.consume_sockets(3, "captive_portal")(config)
-    socket.consume_sockets(1, "captive_portal", socket.SocketType.UDP)(config)
+    web_server_base.consume_captive_dns_sockets(config, "captive_portal")
 
 
 FINAL_VALIDATE_SCHEMA = _final_validate
@@ -106,16 +94,4 @@ async def to_code(config):
     if config[CONF_COMPRESSION] == "gzip":
         cg.add_define("USE_CAPTIVE_PORTAL_GZIP")
 
-    if CORE.using_arduino and (CORE.is_esp8266 or CORE.is_libretiny or CORE.is_rp2):
-        cg.add_library("DNSServer", None)
-
-
-# Only compile the ESP-IDF DNS server when using ESP-IDF framework
-FILTER_SOURCE_FILES = filter_source_files_from_platform(
-    {
-        "dns_server_esp32_idf.cpp": {
-            PlatformFramework.ESP32_ARDUINO,
-            PlatformFramework.ESP32_IDF,
-        },
-    }
-)
+    web_server_base.add_captive_dns_library()

esphome/components/captive_portal/captive_portal.cpp

@@ -82,17 +82,7 @@ void CaptivePortal::start() {
     this->base_->add_handler_without_auth(this);
   }
 
-  network::IPAddress ip = wifi::global_wifi_component->wifi_soft_ap_ip();
-
-#if defined(USE_ESP32)
-  // Create DNS server instance for ESP-IDF
-  this->dns_server_ = make_unique<DNSServer>();
-  this->dns_server_->start(ip);
-#elif defined(USE_ARDUINO)
-  this->dns_server_ = make_unique<DNSServer>();
-  this->dns_server_->setErrorReplyCode(DNSReplyCode::NoError);
-  this->dns_server_->start(53, ESPHOME_F("*"), ip);
-#endif
+  this->dns_.start(wifi::global_wifi_component->wifi_soft_ap_ip());
 
   this->initialized_ = true;
   this->active_ = true;

esphome/components/captive_portal/captive_portal.h

@@ -1,16 +1,11 @@
 #pragma once
 #include "esphome/core/defines.h"
 #ifdef USE_CAPTIVE_PORTAL
-#include <memory>
-#if defined(USE_ESP32)
-#include "dns_server_esp32_idf.h"
-#elif defined(USE_ARDUINO)
-#include <DNSServer.h>
-#endif
 #include "esphome/core/component.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/preferences.h"
 #include "esphome/components/web_server_base/web_server_base.h"
+#include "esphome/components/web_server_base/captive_dns.h"
 
 namespace esphome::captive_portal {
 
@@ -19,17 +14,7 @@ class CaptivePortal final : public AsyncWebHandler, public Component {
   CaptivePortal(web_server_base::WebServerBase *base);
   void setup() override;
   void dump_config() override;
-  void loop() override {
-#if defined(USE_ESP32)
-    if (this->dns_server_ != nullptr) {
-      this->dns_server_->process_next_request();
-    }
-#elif defined(USE_ARDUINO)
-    if (this->dns_server_ != nullptr) {
-      this->dns_server_->processNextRequest();
-    }
-#endif
-  }
+  void loop() override { this->dns_.loop(); }
   float get_setup_priority() const override;
   void start();
   bool is_active() const { return this->active_; }
@@ -37,10 +22,7 @@ class CaptivePortal final : public AsyncWebHandler, public Component {
     this->active_ = false;
     this->disable_loop();  // Stop processing DNS requests
     this->base_->deinit();
-    if (this->dns_server_ != nullptr) {
-      this->dns_server_->stop();
-      this->dns_server_ = nullptr;
-    }
+    this->dns_.stop();
   }
 
   bool canHandle(AsyncWebServerRequest *request) const override {
@@ -60,9 +42,7 @@ class CaptivePortal final : public AsyncWebHandler, public Component {
   web_server_base::WebServerBase *base_;
   bool initialized_{false};
   bool active_{false};
-#if defined(USE_ARDUINO) || defined(USE_ESP32)
-  std::unique_ptr<DNSServer> dns_server_{nullptr};
-#endif
+  web_server_base::CaptiveDNS dns_;
 };
 
 extern CaptivePortal *global_captive_portal;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)

esphome/components/const/__init__.py

@@ -10,6 +10,7 @@ CONF_ACCELEROMETER_RANGE = "accelerometer_range"
 CONF_B_CONSTANT = "b_constant"
 CONF_BREATH_VOC_EQUIVALENT = "breath_voc_equivalent"
 CONF_BYTE_ORDER = "byte_order"
+CONF_CHANNEL_COLORS = "channel_colors"
 CONF_CLIMATE_ID = "climate_id"
 CONF_CO2_EQUIVALENT = "co2_equivalent"
 CONF_COLOR_DEPTH = "color_depth"
@@ -22,6 +23,7 @@ CONF_GYROSCOPE_ODR = "gyroscope_odr"
 CONF_GYROSCOPE_RANGE = "gyroscope_range"
 CONF_IAQ = "iaq"
 CONF_IGNORE_NOT_FOUND = "ignore_not_found"
+CONF_IS_WRGB = "is_wrgb"
 CONF_LABEL = "label"
 CONF_LIBRETINY = "libretiny"
 CONF_LOOP = "loop"

esphome/components/esp32/__init__.py

@@ -1073,6 +1073,26 @@ def _parse_pio_platform_version(value):
         return value
 
 
+def _normalize_p4_engineering_sample(value: ConfigType) -> bool:
+    """Fill in CONF_ENGINEERING_SAMPLE when unset, warning that production
+    silicon (rev3) is assumed. Returns the normalized flag."""
+    if (engineering_sample := value.get(CONF_ENGINEERING_SAMPLE)) is None:
+        _LOGGER.warning(
+            "Defaulting to ESP32-P4 production silicon (rev3).\n"
+            "If you have an early engineering sample (pre-rev3), add this to your config:\n"
+            "\n"
+            "  esp32:\n"
+            "    engineering_sample: true\n"
+            "\n"
+            "To check your chip revision, look for 'chip revision: vX.Y' in the boot log.\n"
+            "Engineering samples will show a revision below v3.0.\n"
+            "The 'debug:' component also reports the revision (e.g. Revision: 100 = v1.0, 300 = v3.0)."
+        )
+        engineering_sample = False
+        value[CONF_ENGINEERING_SAMPLE] = engineering_sample
+    return engineering_sample
+
+
 def _detect_variant(value):
     board = value.get(CONF_BOARD)
     variant = value.get(CONF_VARIANT)
@@ -1085,6 +1105,8 @@ def _detect_variant(value):
         # name rather than carrying a PIO board name through the IDF build.
         if CORE.using_toolchain_esp_idf:
             value = value.copy()
+            if variant == VARIANT_ESP32P4:
+                _normalize_p4_engineering_sample(value)
             value[CONF_BOARD] = VARIANT_FRIENDLY[variant].lower()
             return value
         if variant not in STANDARD_BOARDS:
@@ -1095,22 +1117,8 @@ def _detect_variant(value):
             )
         value = value.copy()
         value[CONF_BOARD] = STANDARD_BOARDS[variant]
-        if variant == VARIANT_ESP32P4:
-            engineering_sample = value.get(CONF_ENGINEERING_SAMPLE)
-            if engineering_sample is None:
-                _LOGGER.warning(
-                    "No board specified for ESP32-P4. Defaulting to production silicon (rev3).\n"
-                    "If you have an early engineering sample (pre-rev3), add this to your config:\n"
-                    "\n"
-                    "  esp32:\n"
-                    "    engineering_sample: true\n"
-                    "\n"
-                    "To check your chip revision, look for 'chip revision: vX.Y' in the boot log.\n"
-                    "Engineering samples will show a revision below v3.0.\n"
-                    "The 'debug:' component also reports the revision (e.g. Revision: 100 = v1.0, 300 = v3.0)."
-                )
-            elif engineering_sample:
-                value[CONF_BOARD] = "esp32-p4-evboard"
+        if variant == VARIANT_ESP32P4 and _normalize_p4_engineering_sample(value):
+            value[CONF_BOARD] = "esp32-p4-evboard"
     elif board in BOARDS:
         variant = variant or BOARDS[board][KEY_VARIANT]
         if variant != BOARDS[board][KEY_VARIANT]:
@@ -1120,6 +1128,14 @@ def _detect_variant(value):
             )
         value = value.copy()
         value[CONF_VARIANT] = variant
+        if variant == VARIANT_ESP32P4:
+            board_is_es = BOARDS[board].get("engineering_sample", False)
+            engineering_sample = value.setdefault(CONF_ENGINEERING_SAMPLE, board_is_es)
+            if engineering_sample != board_is_es:
+                raise cv.Invalid(
+                    f"'{CONF_ENGINEERING_SAMPLE}' does not match board '{board}'",
+                    path=[CONF_ENGINEERING_SAMPLE],
+                )
     elif not variant:
         raise cv.Invalid(
             "This board is unknown, if you are sure you want to compile with this board selection, "
@@ -1131,6 +1147,9 @@ def _detect_variant(value):
             "This board is unknown; the specified variant '%s' will be used but this may not work as expected.",
             variant,
         )
+        if variant == VARIANT_ESP32P4:
+            value = value.copy()
+            _normalize_p4_engineering_sample(value)
     return value
 
 
@@ -1434,20 +1453,6 @@ def final_validate(config) -> None:
                 path=[CONF_ENGINEERING_SAMPLE],
             )
         )
-    if (
-        config[CONF_VARIANT] == VARIANT_ESP32P4
-        and config.get(CONF_ENGINEERING_SAMPLE) is not None
-    ):
-        board_is_es = BOARDS.get(config[CONF_BOARD], {}).get(
-            "engineering_sample", False
-        )
-        if config[CONF_ENGINEERING_SAMPLE] != board_is_es:
-            errs.append(
-                cv.Invalid(
-                    f"'{CONF_ENGINEERING_SAMPLE}' does not match board '{config[CONF_BOARD]}'",
-                    path=[CONF_ENGINEERING_SAMPLE],
-                )
-            )
     if advanced[CONF_EXECUTE_FROM_PSRAM]:
         if config[CONF_VARIANT] not in {VARIANT_ESP32S3, VARIANT_ESP32P4}:
             errs.append(
@@ -2518,15 +2523,14 @@ async def to_code(config):
             f"CONFIG_ESPTOOLPY_FLASHFREQ_{flash_frequency[:-3]}M", True
         )
 
-    # ESP32-P4: ESP-IDF 5.5.3 changed the default of ESP32P4_SELECTS_REV_LESS_V3
-    # from y to n. PlatformIO uses sections.ld.in (for rev <3) or
-    # sections.rev3.ld.in (for rev >=3) based on board definition.
-    # Set the sdkconfig option to match the board's chip revision.
+    # ESP32-P4: pre-v3 and rev3 (v3.0+) silicon are not binary compatible.
+    # CONFIG_ESP32P4_SELECTS_REV_LESS_V3 selects which layout ESP-IDF links;
+    # validation normalizes CONF_ENGINEERING_SAMPLE from the board when unset.
     if variant == VARIANT_ESP32P4:
-        is_eng_sample = BOARDS.get(config[CONF_BOARD], {}).get(
-            "engineering_sample", False
+        add_idf_sdkconfig_option(
+            "CONFIG_ESP32P4_SELECTS_REV_LESS_V3",
+            config.get(CONF_ENGINEERING_SAMPLE, False),
         )
-        add_idf_sdkconfig_option("CONFIG_ESP32P4_SELECTS_REV_LESS_V3", is_eng_sample)
 
     # Set minimum chip revision for ESP32 variant
     # Setting this to 3.0 or higher reduces flash size by excluding workaround code,

esphome/components/esp32_rmt_led_strip/led_strip.cpp

@@ -221,46 +221,12 @@ void ESP32RMTLEDStripLightOutput::write_state(light::LightState *state) {
 }
 
 light::ESPColorView ESP32RMTLEDStripLightOutput::get_view_internal(int32_t index) const {
-  int32_t r = 0, g = 0, b = 0;
-  switch (this->rgb_order_) {
-    case ORDER_RGB:
-      r = 0;
-      g = 1;
-      b = 2;
-      break;
-    case ORDER_RBG:
-      r = 0;
-      g = 2;
-      b = 1;
-      break;
-    case ORDER_GRB:
-      r = 1;
-      g = 0;
-      b = 2;
-      break;
-    case ORDER_GBR:
-      r = 2;
-      g = 0;
-      b = 1;
-      break;
-    case ORDER_BGR:
-      r = 2;
-      g = 1;
-      b = 0;
-      break;
-    case ORDER_BRG:
-      r = 1;
-      g = 2;
-      b = 0;
-      break;
-  }
-  uint8_t multiplier = this->is_rgbw_ || this->is_wrgb_ ? 4 : 3;
-  uint8_t white = this->is_wrgb_ ? 0 : this->white_index_;
-
-  return {this->buf_ + (index * multiplier) + r + (white <= r),
-          this->buf_ + (index * multiplier) + g + (white <= g),
-          this->buf_ + (index * multiplier) + b + (white <= b),
-          this->is_rgbw_ || this->is_wrgb_ ? this->buf_ + (index * multiplier) + white : nullptr,
+  const light::ChannelColors &colors = this->channel_colors_;
+  uint8_t *led = this->buf_ + (index * colors.bytes_per_led());
+  return {led + colors.r,
+          led + colors.g,
+          led + colors.b,
+          colors.has_white() ? led + colors.w : nullptr,
           &this->effect_data_[index],
           &this->correction_};
 }
@@ -271,46 +237,12 @@ void ESP32RMTLEDStripLightOutput::dump_config() {
                 "  Pin: %u",
                 this->pin_);
   ESP_LOGCONFIG(TAG, "  RMT Symbols: %" PRIu32, this->rmt_symbols_);
-  const char *rgb_order;
-  switch (this->rgb_order_) {
-    case ORDER_RGB:
-      rgb_order = "RGB";
-      break;
-    case ORDER_RBG:
-      rgb_order = "RBG";
-      break;
-    case ORDER_GRB:
-      rgb_order = "GRB";
-      break;
-    case ORDER_GBR:
-      rgb_order = "GBR";
-      break;
-    case ORDER_BGR:
-      rgb_order = "BGR";
-      break;
-    case ORDER_BRG:
-      rgb_order = "BRG";
-      break;
-    default:
-      rgb_order = "UNKNOWN";
-      break;
-  }
-  if (this->is_rgbw_ || this->is_wrgb_) {
-    char rgbw_order[5];
-    uint8_t white = this->is_wrgb_ ? 0 : this->white_index_;
-    uint8_t rgb_index = 0;
-    for (uint8_t i = 0; i < 4; i++) {
-      rgbw_order[i] = i == white ? 'W' : rgb_order[rgb_index++];
-    }
-    rgbw_order[4] = '\0';
-    ESP_LOGCONFIG(TAG, "  RGBW Order: %s", rgbw_order);
-  } else {
-    ESP_LOGCONFIG(TAG, "  RGB Order: %s", rgb_order);
-  }
+  char channel_colors[5];
   ESP_LOGCONFIG(TAG,
+                "  Channel colors: %s\n"
                 "  Max refresh rate: %" PRIu32 "\n"
                 "  Number of LEDs: %u",
-                this->max_refresh_rate_.value_or(0), this->num_leds_);
+                this->channel_colors_.to_string(channel_colors), this->max_refresh_rate_.value_or(0), this->num_leds_);
 }
 
 float ESP32RMTLEDStripLightOutput::get_setup_priority() const { return setup_priority::HARDWARE; }

esphome/components/esp32_rmt_led_strip/led_strip.h

@@ -3,6 +3,7 @@
 #ifdef USE_ESP32
 
 #include "esphome/components/light/addressable_light.h"
+#include "esphome/components/light/channel_colors.h"
 #include "esphome/components/light/light_output.h"
 #include "esphome/core/color.h"
 #include "esphome/core/component.h"
@@ -15,15 +16,6 @@
 
 namespace esphome::esp32_rmt_led_strip {
 
-enum RGBOrder : uint8_t {
-  ORDER_RGB,
-  ORDER_RBG,
-  ORDER_GRB,
-  ORDER_GBR,
-  ORDER_BGR,
-  ORDER_BRG,
-};
-
 struct LedParams {
   rmt_symbol_word_t bit0;
   rmt_symbol_word_t bit1;
@@ -39,7 +31,7 @@ class ESP32RMTLEDStripLightOutput final : public light::AddressableLight {
   int32_t size() const override { return this->num_leds_; }
   light::LightTraits get_traits() override {
     auto traits = light::LightTraits();
-    if (this->is_rgbw_ || this->is_wrgb_) {
+    if (this->channel_colors_.has_white()) {
       traits.set_supported_color_modes({light::ColorMode::RGB_WHITE, light::ColorMode::WHITE});
     } else {
       traits.set_supported_color_modes({light::ColorMode::RGB});
@@ -50,13 +42,7 @@ class ESP32RMTLEDStripLightOutput final : public light::AddressableLight {
   void set_pin(uint8_t pin) { this->pin_ = pin; }
   void set_inverted(bool inverted) { this->invert_out_ = inverted; }
   void set_num_leds(uint16_t num_leds) { this->num_leds_ = num_leds; }
-  void set_is_rgbw(bool is_rgbw) { this->is_rgbw_ = is_rgbw; }
-  void set_is_wrgb(bool is_wrgb) { this->is_wrgb_ = is_wrgb; }
-  void set_rgbw_order(uint8_t white_index) {
-    this->is_rgbw_ = true;
-    this->is_wrgb_ = false;
-    this->white_index_ = white_index;
-  }
+  void set_channel_colors(light::ChannelColors channel_colors) { this->channel_colors_ = channel_colors; }
   void set_use_dma(bool use_dma) { this->use_dma_ = use_dma; }
   void set_use_psram(bool use_psram) { this->use_psram_ = use_psram; }
 
@@ -66,7 +52,6 @@ class ESP32RMTLEDStripLightOutput final : public light::AddressableLight {
   void set_led_params(uint32_t bit0_high, uint32_t bit0_low, uint32_t bit1_high, uint32_t bit1_low,
                       uint32_t reset_time_high, uint32_t reset_time_low);
 
-  void set_rgb_order(RGBOrder rgb_order) { this->rgb_order_ = rgb_order; }
   void set_rmt_symbols(uint32_t rmt_symbols) { this->rmt_symbols_ = rmt_symbols; }
 
   void clear_effect_data() override {
@@ -79,7 +64,7 @@ class ESP32RMTLEDStripLightOutput final : public light::AddressableLight {
  protected:
   light::ESPColorView get_view_internal(int32_t index) const override;
 
-  size_t get_buffer_size_() const { return this->num_leds_ * (this->is_rgbw_ || this->is_wrgb_ ? 4 : 3); }
+  size_t get_buffer_size_() const { return this->num_leds_ * this->channel_colors_.bytes_per_led(); }
 
   uint8_t *buf_{nullptr};
   uint8_t *effect_data_{nullptr};
@@ -94,15 +79,11 @@ class ESP32RMTLEDStripLightOutput final : public light::AddressableLight {
   uint32_t rmt_symbols_{48};
   uint8_t pin_;
   uint16_t num_leds_;
-  bool is_rgbw_{false};
-  bool is_wrgb_{false};
-  // An index after the RGB channels makes offset adjustment a no-op for three-channel strips.
-  uint8_t white_index_{3};
   bool use_dma_{false};
   bool use_psram_{false};
   bool invert_out_{false};
 
-  RGBOrder rgb_order_{ORDER_RGB};
+  light::ChannelColors channel_colors_{0, 1, 2, light::ChannelColors::NO_WHITE};
 
   uint32_t last_refresh_{0};
   optional<uint32_t> max_refresh_rate_{};

esphome/components/esp32_rmt_led_strip/light.py

@@ -1,10 +1,9 @@
 from dataclasses import dataclass
-import logging
 
 from esphome import pins
 import esphome.codegen as cg
 from esphome.components import esp32, esp32_rmt, light
-from esphome.components.const import CONF_USE_PSRAM
+from esphome.components.const import CONF_CHANNEL_COLORS, CONF_IS_WRGB, CONF_USE_PSRAM
 from esphome.components.esp32 import include_builtin_idf_component
 import esphome.config_validation as cv
 from esphome.const import (
@@ -22,8 +21,6 @@ from esphome.const import (
 )
 from esphome.types import ConfigType
 
-_LOGGER = logging.getLogger(__name__)
-
 CODEOWNERS = ["@jesserockz"]
 DEPENDENCIES = ["esp32"]
 
@@ -32,17 +29,6 @@ ESP32RMTLEDStripLightOutput = esp32_rmt_led_strip_ns.class_(
     "ESP32RMTLEDStripLightOutput", light.AddressableLight
 )
 
-RGBOrder = esp32_rmt_led_strip_ns.enum("RGBOrder")
-
-RGB_ORDERS = {
-    "RGB": RGBOrder.ORDER_RGB,
-    "RBG": RGBOrder.ORDER_RBG,
-    "GRB": RGBOrder.ORDER_GRB,
-    "GBR": RGBOrder.ORDER_GBR,
-    "BGR": RGBOrder.ORDER_BGR,
-    "BRG": RGBOrder.ORDER_BRG,
-}
-
 
 @dataclass
 class LEDStripTimings:
@@ -62,8 +48,6 @@ CHIPSETS = {
     "SM16703": LEDStripTimings(300, 900, 900, 300, 0, 0),
 }
 
-CONF_IS_WRGB = "is_wrgb"
-CONF_RGBW_ORDER = "rgbw_order"
 CONF_BIT0_HIGH = "bit0_high"
 CONF_BIT0_LOW = "bit0_low"
 CONF_BIT1_HIGH = "bit1_high"
@@ -72,26 +56,6 @@ CONF_RESET_HIGH = "reset_high"
 CONF_RESET_LOW = "reset_low"
 
 
-def _validate_rgbw_order(value: str) -> str:
-    value = cv.string(value).upper()
-    if len(value) != 4 or set(value) != set("RGBW"):
-        raise cv.Invalid("RGBW order must be a permutation of RGBW")
-    return value
-
-
-def _split_rgbw_order(rgbw_order: str) -> tuple[str, int]:
-    return rgbw_order.replace("W", ""), rgbw_order.index("W")
-
-
-def _validate_rgbw_order_exclusivity(config: ConfigType) -> ConfigType:
-    if CONF_RGBW_ORDER in config and (config[CONF_IS_RGBW] or config[CONF_IS_WRGB]):
-        raise cv.Invalid(
-            f"'{CONF_RGBW_ORDER}' cannot be used with '{CONF_IS_RGBW}' or "
-            f"'{CONF_IS_WRGB}'"
-        )
-    return config
-
-
 CONFIG_SCHEMA = cv.All(
     esp32.only_on_variant(
         unsupported=list(esp32_rmt.VARIANTS_NO_RMT),
@@ -102,8 +66,11 @@ CONFIG_SCHEMA = cv.All(
             cv.GenerateID(CONF_OUTPUT_ID): cv.declare_id(ESP32RMTLEDStripLightOutput),
             cv.Required(CONF_PIN): pins.internal_gpio_output_pin_schema,
             cv.Required(CONF_NUM_LEDS): cv.positive_not_null_int,
-            cv.Optional(CONF_RGB_ORDER): cv.enum(RGB_ORDERS, upper=True),
-            cv.Optional(CONF_RGBW_ORDER): _validate_rgbw_order,
+            cv.Optional(CONF_CHANNEL_COLORS): light.validate_channel_colors,
+            # Deprecated in favour of CONF_CHANNEL_COLORS, remove in 2027.3.0
+            cv.Optional(CONF_RGB_ORDER): cv.one_of(*light.RGB_ORDERS, upper=True),
+            cv.Optional(CONF_IS_RGBW): cv.boolean,
+            cv.Optional(CONF_IS_WRGB): cv.boolean,
             cv.SplitDefault(
                 CONF_RMT_SYMBOLS,
                 esp32=192,
@@ -117,8 +84,6 @@ CONFIG_SCHEMA = cv.All(
             ): cv.int_range(min=2),
             cv.Optional(CONF_MAX_REFRESH_RATE): cv.positive_time_period_microseconds,
             cv.Optional(CONF_CHIPSET): cv.one_of(*CHIPSETS, upper=True),
-            cv.Optional(CONF_IS_RGBW, default=False): cv.boolean,
-            cv.Optional(CONF_IS_WRGB, default=False): cv.boolean,
             cv.Optional(CONF_USE_DMA): cv.All(
                 esp32.only_on_variant(
                     supported=[esp32.VARIANT_ESP32P4, esp32.VARIANT_ESP32S3]
@@ -153,12 +118,13 @@ CONFIG_SCHEMA = cv.All(
         }
     ).extend(cv.COMPONENT_SCHEMA),
     cv.has_exactly_one_key(CONF_CHIPSET, CONF_BIT0_HIGH),
-    cv.has_exactly_one_key(CONF_RGB_ORDER, CONF_RGBW_ORDER),
-    _validate_rgbw_order_exclusivity,
+    light.migrate_channel_colors(
+        removed_in="2027.3.0", component="esp32_rmt_led_strip"
+    ),
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     # Re-enable ESP-IDF's RMT driver (excluded by default to save compile time)
     include_builtin_idf_component("esp_driver_rmt")
 
@@ -198,14 +164,9 @@ async def to_code(config):
             )
         )
 
-    if (rgbw_order := config.get(CONF_RGBW_ORDER)) is not None:
-        rgb_order, white_index = _split_rgbw_order(rgbw_order)
-        cg.add(var.set_rgb_order(RGB_ORDERS[rgb_order]))
-        cg.add(var.set_rgbw_order(white_index))
-    else:
-        cg.add(var.set_rgb_order(config[CONF_RGB_ORDER]))
-        cg.add(var.set_is_rgbw(config[CONF_IS_RGBW]))
-        cg.add(var.set_is_wrgb(config[CONF_IS_WRGB]))
+    cg.add(
+        var.set_channel_colors(light.channel_colors_struct(config[CONF_CHANNEL_COLORS]))
+    )
     cg.add(var.set_use_psram(config[CONF_USE_PSRAM]))
     cg.add(var.set_rmt_symbols(config[CONF_RMT_SYMBOLS]))
     if CONF_USE_DMA in config:

esphome/components/file/image.py

@@ -23,6 +23,7 @@ from esphome.components.image import (
     get_image_type_enum,
     get_transparency_enum,
     is_svg_file,
+    validate_byte_order,
     validate_settings,
     validate_transparency,
     validate_type,
@@ -200,7 +201,7 @@ OPTIONS_SCHEMA = {
         "NONE", "FLOYDSTEINBERG", upper=True
     ),
     cv.Optional(CONF_INVERT_ALPHA, default=False): cv.boolean,
-    cv.Optional(CONF_BYTE_ORDER): cv.one_of("BIG_ENDIAN", "LITTLE_ENDIAN", upper=True),
+    cv.Optional(CONF_BYTE_ORDER): validate_byte_order,
     cv.Optional(CONF_TRANSPARENCY, default=CONF_OPAQUE): validate_transparency(),
 }
 

esphome/components/gpio_expander/__init__.py

@@ -0,0 +1,22 @@
+from esphome import pins
+import esphome.config_validation as cv
+from esphome.const import CONF_ALLOW_OTHER_USES, CONF_INTERRUPT_PIN, CONF_INVERTED
+from esphome.types import ConfigType
+
+
+def validate_interrupt_pin(value: ConfigType) -> ConfigType:
+    # The expander components own INT polarity (active-low, hardcoded falling-edge ISR)
+    # and install a single ISR per GPIO, so neither inversion nor sharing is supported.
+    value = pins.internal_gpio_input_pin_schema(value)
+    if value.get(CONF_INVERTED):
+        raise cv.Invalid(
+            f"'{CONF_INVERTED}: true' is not supported on '{CONF_INTERRUPT_PIN}'; "
+            "the expander INT line is fixed active-low"
+        )
+    if value.get(CONF_ALLOW_OTHER_USES):
+        raise cv.Invalid(
+            f"'{CONF_ALLOW_OTHER_USES}: true' is not supported on '{CONF_INTERRUPT_PIN}'; "
+            "sharing the interrupt pin between multiple components is not implemented. "
+            f"Remove the '{CONF_INTERRUPT_PIN}' to fall back to polling."
+        )
+    return value

esphome/components/image/__init__.py

@@ -10,7 +10,14 @@ from PIL import Image, UnidentifiedImageError
 import esphome.codegen as cg
 from esphome.components.const import CONF_BYTE_ORDER, KEY_METADATA
 import esphome.config_validation as cv
-from esphome.const import CONF_DEFAULTS, CONF_FILE, CONF_ID, CONF_PLATFORM, CONF_TYPE
+from esphome.const import (
+    CONF_DEFAULTS,
+    CONF_FILE,
+    CONF_FILES,
+    CONF_ID,
+    CONF_PLATFORM,
+    CONF_TYPE,
+)
 from esphome.core import CORE
 from esphome.types import ConfigType
 
@@ -48,6 +55,9 @@ TRANSPARENCY_TYPES = (
     CONF_ALPHA_CHANNEL,
 )
 
+# Shared validator for the image platform schemas and `_drop_incompatible_byte_order`.
+validate_byte_order = cv.one_of("BIG_ENDIAN", "LITTLE_ENDIAN", upper=True)
+
 
 def get_image_type_enum(type):
     return getattr(ImageType, f"IMAGE_TYPE_{type.upper()}")
@@ -404,6 +414,120 @@ def get_image_metadata(image_id: str) -> ImageMetaData | None:
     return get_all_image_metadata().get(image_id)
 
 
+# ---------------------------------------------------------------------------
+# `defaults:`/`files:` expansion: a `platform:` entry merges shared `defaults:`
+# into every `files:` entry; the platform's CONFIG_SCHEMA validates each.
+# Permanent, unlike the legacy migration below.
+# ---------------------------------------------------------------------------
+
+
+def _drop_incompatible_byte_order(
+    merged: dict, explicit: dict, *, index: int | None = None
+) -> dict:
+    """Drop `byte_order` when the resolved type doesn't support it, unless written directly on `explicit`.
+
+    With `index`, inherited values are validated before being dropped (the legacy flattener always drops).
+    """
+    if CONF_BYTE_ORDER in explicit:
+        return merged
+    type_class = IMAGE_TYPE.get(str(merged.get(CONF_TYPE, "")).upper())
+    if (
+        CONF_BYTE_ORDER in merged
+        and isinstance(type_class, type)
+        and issubclass(type_class, ImageEncoder)
+        and not type_class.is_endian()
+    ):
+        if index is not None:
+            try:
+                validate_byte_order(merged[CONF_BYTE_ORDER])
+            except cv.Invalid as exc:
+                exc.prepend([index])
+                raise
+        del merged[CONF_BYTE_ORDER]
+    return merged
+
+
+def _expand_platform_entry(index: int, entry: dict) -> list[dict]:
+    if CONF_FILES not in entry:
+        if CONF_DEFAULTS in entry:
+            raise cv.Invalid(
+                f"'{CONF_DEFAULTS}' may only be used together with '{CONF_FILES}'",
+                path=[index],
+            )
+        return [entry]
+
+    extra_keys = set(entry) - {CONF_PLATFORM, CONF_DEFAULTS, CONF_FILES}
+    if extra_keys:
+        raise cv.Invalid(
+            f"'{CONF_FILES}' cannot be combined with "
+            f"{', '.join(sorted(extra_keys))} on the same entry",
+            path=[index],
+        )
+
+    files = entry[CONF_FILES]
+    if files is None:
+        raise cv.Invalid(f"'{CONF_FILES}' must not be empty", path=[index])
+    if not isinstance(files, list):
+        raise cv.Invalid(f"'{CONF_FILES}' must be a list", path=[index])
+    if not files:
+        raise cv.Invalid(f"'{CONF_FILES}' must not be empty", path=[index])
+
+    defaults = entry.get(CONF_DEFAULTS, {})
+    if defaults is None:
+        defaults = {}
+    if not isinstance(defaults, dict):
+        raise cv.Invalid(f"'{CONF_DEFAULTS}' must be a mapping", path=[index])
+    # Neither `id:` nor `platform:` makes sense inside `defaults:`.
+    for disallowed in (CONF_ID, CONF_PLATFORM):
+        if disallowed in defaults:
+            raise cv.Invalid(
+                f"'{disallowed}' is not allowed inside '{CONF_DEFAULTS}'",
+                path=[index],
+            )
+
+    from esphome import yaml_util
+
+    platform = entry[CONF_PLATFORM]
+    result: list[dict] = []
+    for file_entry in files:
+        if not isinstance(file_entry, dict):
+            raise cv.Invalid(
+                f"each entry in '{CONF_FILES}' must be a mapping", path=[index]
+            )
+        # The platform is chosen by the entry's own `platform:` key, not per file.
+        if CONF_PLATFORM in file_entry:
+            raise cv.Invalid(
+                f"'{CONF_PLATFORM}' is not allowed inside '{CONF_FILES}'",
+                path=[index],
+            )
+        # Keep the `files:` item's source range so whole-entry errors anchor there;
+        # `make_data_base` needs a real ESPHomeDataBase, so skip it for plain dicts.
+        source = (
+            file_entry if isinstance(file_entry, yaml_util.ESPHomeDataBase) else None
+        )
+        merged = yaml_util.make_data_base(
+            {CONF_PLATFORM: platform, **defaults, **file_entry}, source
+        )
+        result.append(_drop_incompatible_byte_order(merged, file_entry, index=index))
+    return result
+
+
+def expand_platform_config(config: list) -> list:
+    """Expand `defaults:`/`files:` entries; the platform's own CONFIG_SCHEMA validates each result."""
+    result = []
+    for i, entry in enumerate(config):
+        if isinstance(entry, dict) and CONF_PLATFORM in entry:
+            result.extend(_expand_platform_entry(i, entry))
+        else:
+            result.append(entry)
+    return result
+
+
+EXPAND_PLATFORM_CONFIG = expand_platform_config
+
+# --------------------- end defaults/files expansion -------------------------
+
+
 # ---------------------------------------------------------------------------
 # Legacy top-level component -> `image:` platform deprecation helpers
 # -- REMOVE after 2027.1.0 together with the `animation:`/`online_image:` shims.
@@ -496,11 +620,17 @@ def _is_legacy_image_format(config: object) -> bool:
     proper error instead of the migration silently dropping the input.
     """
     if isinstance(config, list):
-        # A bare list of (not-yet-platform-tagged) image dicts.
+        # Exclude `files:` entries -- the list branch would otherwise silently
+        # migrate them to `platform: file` instead of raising the missing-platform error.
         return bool(config) and all(
-            isinstance(entry, dict) and CONF_PLATFORM not in entry for entry in config
+            isinstance(entry, dict)
+            and CONF_PLATFORM not in entry
+            and CONF_FILES not in entry
+            for entry in config
         )
-    if not isinstance(config, dict):
+    if not isinstance(config, dict) or CONF_PLATFORM in config or CONF_FILES in config:
+        # `platform:`/`files:` dicts are new-format (left for list-wrapping +
+        # expansion); the legacy flattener has no `files:` branch and would drop them.
         return False
     # A single image dict, or the grouped `defaults:`/`images:`/type-key form.
     return (
@@ -532,18 +662,8 @@ def _flatten_legacy_image_config(config: object) -> list[dict]:
 
     def _add(entry: dict, extra: dict) -> None:
         merged = {**defaults, **extra, **entry}
-        # The legacy `defaults:`/type-grouped forms only applied `byte_order` to
-        # types that support it. Replicate that so an endian default merged into
-        # e.g. a binary image stays valid.
-        type_class = IMAGE_TYPE.get(str(merged.get(CONF_TYPE, "")).upper())
-        if (
-            CONF_BYTE_ORDER in merged
-            and isinstance(type_class, type)
-            and issubclass(type_class, ImageEncoder)
-            and not type_class.is_endian()
-        ):
-            del merged[CONF_BYTE_ORDER]
-        result.append(merged)
+        # Always drop, matching the pre-platform behavior -- see `_drop_incompatible_byte_order`.
+        result.append(_drop_incompatible_byte_order(merged, {}))
 
     def _add_entries(entries: object, extra: dict) -> None:
         # `entries` may be a single image dict or a list of them; non-dict

esphome/components/light/__init__.py

@@ -1,9 +1,12 @@
+from collections.abc import Callable
 from dataclasses import dataclass, field
 import enum
+import logging
 
 import esphome.automation as auto
 import esphome.codegen as cg
 from esphome.components import mqtt, power_supply, web_server
+from esphome.components.const import CONF_CHANNEL_COLORS, CONF_IS_WRGB
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_BLUE,
@@ -23,6 +26,7 @@ from esphome.const import (
     CONF_ICON,
     CONF_ID,
     CONF_INITIAL_STATE,
+    CONF_IS_RGBW,
     CONF_MQTT_ID,
     CONF_NAME,
     CONF_ON_STATE,
@@ -32,6 +36,7 @@ from esphome.const import (
     CONF_POWER_SUPPLY,
     CONF_RED,
     CONF_RESTORE_MODE,
+    CONF_RGB_ORDER,
     CONF_STATE,
     CONF_TRIGGER_ID,
     CONF_WARM_WHITE,
@@ -61,6 +66,7 @@ from .effects import (
 from .types import (  # noqa: F401
     AddressableLight,
     AddressableLightState,
+    ChannelColors,
     ColorMode,
     LightOutput,
     LightState,
@@ -71,6 +77,8 @@ from .types import (  # noqa: F401
     light_ns,
 )
 
+_LOGGER = logging.getLogger(__name__)
+
 CODEOWNERS = ["@esphome/core"]
 IS_PLATFORM_COMPONENT = True
 
@@ -165,6 +173,104 @@ def available_effects_str(effects: list) -> str:
     return ", ".join(f"'{name}'" for name in available) if available else "none"
 
 
+# Accepted values of the deprecated `rgb_order` key.
+RGB_ORDERS = ("RGB", "RBG", "GRB", "GBR", "BGR", "BRG")
+
+_RGB_CHANNELS = frozenset("RGB")
+_RGBW_CHANNELS = frozenset("RGBW")
+
+
+def validate_channel_colors(value: str) -> str:
+    """Validate the channel order of an addressable strip, e.g. "GRB" or "WRGB"."""
+    value = cv.string_strict(value).upper()
+    channels = frozenset(value)
+    if len(channels) != len(value) or channels not in (_RGB_CHANNELS, _RGBW_CHANNELS):
+        raise cv.Invalid(
+            f"'{value}' is not a valid channel order. List each of R, G and B exactly "
+            "once, optionally with a single W, in the order the strip expects them "
+            "(for example GRB, GRBW or WRGB)"
+        )
+    return value
+
+
+def channel_colors_struct(value: str) -> cg.StructInitializer:
+    """Build the C++ `light::ChannelColors` for a validated channel order string."""
+    return cg.StructInitializer(
+        ChannelColors,
+        ("r", value.index("R")),
+        ("g", value.index("G")),
+        ("b", value.index("B")),
+        (
+            "w",
+            value.index("W")
+            if "W" in value
+            else cg.RawExpression(f"{ChannelColors}::NO_WHITE"),
+        ),
+    )
+
+
+def _quote_and_join(keys: list[str]) -> str:
+    """Quote each key and join them into a readable list, e.g. "'a', 'b' and 'c'"."""
+    quoted = [f"'{key}'" for key in keys]
+    if len(quoted) == 1:
+        return quoted[0]
+    return f"{', '.join(quoted[:-1])} and {quoted[-1]}"
+
+
+def migrate_channel_colors(
+    *, removed_in: str, component: str
+) -> Callable[[ConfigType], ConfigType]:
+    """Fold the deprecated `rgb_order`, `is_rgbw` and `is_wrgb` keys into `channel_colors`.
+
+    This also enforces that `channel_colors` is set, which the schema cannot do on its
+    own while the deprecated keys are still accepted. After this runs, `to_code` only
+    ever sees `channel_colors`.
+    """
+
+    def validator(config: ConfigType) -> ConfigType:
+        config = config.copy()
+        deprecated = [
+            key for key in (CONF_RGB_ORDER, CONF_IS_RGBW, CONF_IS_WRGB) if key in config
+        ]
+        if CONF_CHANNEL_COLORS in config:
+            if deprecated:
+                raise cv.Invalid(
+                    f"'{CONF_CHANNEL_COLORS}' cannot be combined with "
+                    f"{_quote_and_join(deprecated)}"
+                )
+            return config
+        if CONF_RGB_ORDER not in config:
+            raise cv.Invalid(
+                f"'{CONF_CHANNEL_COLORS}' is required", path=[CONF_CHANNEL_COLORS]
+            )
+        rgb_order = config.pop(CONF_RGB_ORDER)
+        is_rgbw = config.pop(CONF_IS_RGBW, False)
+        is_wrgb = config.pop(CONF_IS_WRGB, False)
+        if is_rgbw and is_wrgb:
+            raise cv.Invalid(
+                f"'{CONF_IS_RGBW}' and '{CONF_IS_WRGB}' cannot both be enabled"
+            )
+        if is_wrgb:
+            channel_colors = f"W{rgb_order}"
+        elif is_rgbw:
+            channel_colors = f"{rgb_order}W"
+        else:
+            channel_colors = rgb_order
+        _LOGGER.warning(
+            "[%s] %s %s deprecated, use '%s: %s'. Will be removed in %s",
+            component,
+            _quote_and_join(deprecated),
+            "are" if len(deprecated) > 1 else "is",
+            CONF_CHANNEL_COLORS,
+            channel_colors,
+            removed_in,
+        )
+        config[CONF_CHANNEL_COLORS] = channel_colors
+        return config
+
+    return validator
+
+
 def _final_validate(config: ConfigType) -> None:
     """Validate all recorded effect name references against their target lights.
 

esphome/components/light/channel_colors.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <cstdint>
+
+namespace esphome::light {
+
+/// Which byte of an addressable LED's data carries each colour.
+///
+/// Built from a configuration string such as "GRB" or "WRGB": every field holds the
+/// position that colour occupies in the bytes the strip expects. `w` is NO_WHITE when
+/// the strip has no separate white channel.
+struct ChannelColors {
+  /// Value of `w` for a strip that only has red, green and blue channels.
+  static constexpr uint8_t NO_WHITE = 0xFF;
+
+  uint8_t r;
+  uint8_t g;
+  uint8_t b;
+  uint8_t w;
+
+  bool has_white() const { return this->w != NO_WHITE; }
+
+  uint8_t bytes_per_led() const { return this->has_white() ? 4 : 3; }
+
+  /// Write the order back out as text, e.g. "GRBW".
+  ///
+  /// `buf` must have room for at least 5 characters. Returns `buf` so the result can be
+  /// passed straight to a log call.
+  const char *to_string(char *buf) const {
+    buf[this->r] = 'R';
+    buf[this->g] = 'G';
+    buf[this->b] = 'B';
+    if (this->has_white()) {
+      buf[this->w] = 'W';
+    }
+    buf[this->bytes_per_led()] = '\0';
+    return buf;
+  }
+};
+
+}  // namespace esphome::light

esphome/components/light/types.py

@@ -16,6 +16,9 @@ LightColorValues = light_ns.class_("LightColorValues")
 LightStateRTCState = light_ns.struct("LightStateRTCState")
 LightCall = light_ns.class_("LightCall")
 
+# Addressable strips
+ChannelColors = light_ns.struct("ChannelColors")
+
 # Color modes
 ColorMode = light_ns.enum("ColorMode", is_class=True)
 COLOR_MODES = {

esphome/components/mcp23016/__init__.py

@@ -1,6 +1,6 @@
 from esphome import pins
 import esphome.codegen as cg
-from esphome.components import i2c
+from esphome.components import gpio_expander, i2c
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_ID,
@@ -25,7 +25,7 @@ CONFIG_SCHEMA = (
     cv.Schema(
         {
             cv.Required(CONF_ID): cv.declare_id(MCP23016),
-            cv.Optional(CONF_INTERRUPT_PIN): pins.internal_gpio_input_pin_schema,
+            cv.Optional(CONF_INTERRUPT_PIN): gpio_expander.validate_interrupt_pin,
         }
     )
     .extend(cv.COMPONENT_SCHEMA)

esphome/components/mcp23xxx_base/__init__.py

@@ -1,8 +1,8 @@
 from esphome import pins
 import esphome.codegen as cg
+from esphome.components import gpio_expander
 import esphome.config_validation as cv
 from esphome.const import (
-    CONF_ALLOW_OTHER_USES,
     CONF_ID,
     CONF_INPUT,
     CONF_INTERRUPT,
@@ -32,28 +32,10 @@ MCP23XXX_INTERRUPT_MODES = {
 }
 
 
-def _validate_interrupt_pin(value):
-    # The MCP component owns INT polarity (active-low, hardcoded falling-edge ISR)
-    # and installs a single ISR per GPIO, so neither inversion nor sharing is supported.
-    value = pins.internal_gpio_input_pin_schema(value)
-    if value.get(CONF_INVERTED):
-        raise cv.Invalid(
-            f"'{CONF_INVERTED}: true' is not supported on '{CONF_INTERRUPT_PIN}'; "
-            "the MCP23xxx INT line is fixed active-low"
-        )
-    if value.get(CONF_ALLOW_OTHER_USES):
-        raise cv.Invalid(
-            f"'{CONF_ALLOW_OTHER_USES}: true' is not supported on '{CONF_INTERRUPT_PIN}'; "
-            "sharing the interrupt pin between multiple MCP23xxx (or other components) "
-            "is not implemented. Remove the interrupt_pin to fall back to polling."
-        )
-    return value
-
-
 MCP23XXX_CONFIG_SCHEMA = cv.Schema(
     {
         cv.Optional(CONF_OPEN_DRAIN_INTERRUPT, default=False): cv.boolean,
-        cv.Optional(CONF_INTERRUPT_PIN): _validate_interrupt_pin,
+        cv.Optional(CONF_INTERRUPT_PIN): gpio_expander.validate_interrupt_pin,
     }
 ).extend(cv.COMPONENT_SCHEMA)
 

esphome/components/modbus/modbus.cpp

@@ -219,14 +219,25 @@ void ModbusServerHub::parse_modbus_frames() {
     this->clear_rx_buffer_(LOG_STR("timeout after partial response"), true);
 }
 
-uint16_t Modbus::find_custom_frame_end_(uint16_t min_length) const {
-  // Custom functions could be any length - we have to rely on the CRC to determine completeness.
+uint16_t Modbus::find_frame_end_by_crc_(uint16_t min_length) const {
+  // Unknown-length functions (user-defined codes, unimplemented management codes, unassigned values)
+  // could be any length - we have to rely on the CRC to determine completeness.
   // If a CRC match is never found, the buffer will eventually overflow and be cleared.
   const uint8_t *raw = &this->rx_buffer_[0];
   const size_t size = this->rx_buffer_.size();
-  for (uint16_t len = min_length; len <= std::min(size, size_t(MAX_FRAME_SIZE)); len++) {
-    if (crc16(raw, len) == 0)
-      return len;
+  const auto max_len = static_cast<uint16_t>(std::min(size, size_t(MAX_FRAME_SIZE)));
+  if (min_length > max_len)
+    return 0;
+  // The Modbus CRC (poly 0xa001, refin/refout false) keeps its running state in the returned value,
+  // so we seed once over the first min_length bytes and extend one byte at a time instead of
+  // recomputing the whole prefix for every candidate length.
+  uint16_t crc = crc16(raw, min_length);
+  if (crc == 0)
+    return min_length;
+  for (uint16_t len = min_length; len < max_len; len++) {
+    crc = crc16(&raw[len], 1, crc);
+    if (crc == 0)
+      return len + 1;
   }
   return 0;
 }
@@ -241,11 +252,11 @@ bool Modbus::parse_modbus_server_frame_() {
   uint8_t address = this->rx_buffer_[0];
   uint8_t function_code = this->rx_buffer_[1];
 
-  if (helpers::is_function_code_custom(function_code)) {
-    frame_length = this->find_custom_frame_end_(frame_length);
+  if (helpers::is_function_code_unknown_length(function_code)) {
+    frame_length = this->find_frame_end_by_crc_(frame_length);
     if (frame_length == 0)
       return size < MAX_FRAME_SIZE;  // Continue to parse until we hit max size
-    ESP_LOGD(TAG, "User-defined function %02X found", function_code);
+    ESP_LOGD(TAG, "Unknown-length function %02X found", function_code);
   } else {
     if (crc16(&this->rx_buffer_[0], frame_length) != 0)
       return false;
@@ -272,11 +283,11 @@ bool ModbusServerHub::parse_modbus_client_frame_() {
   uint8_t address = this->rx_buffer_[0];
   uint8_t function_code = this->rx_buffer_[1];
 
-  if (helpers::is_function_code_custom(function_code)) {
-    frame_length = this->find_custom_frame_end_(frame_length);
+  if (helpers::is_function_code_unknown_length(function_code)) {
+    frame_length = this->find_frame_end_by_crc_(frame_length);
     if (frame_length == 0)
       return size < MAX_FRAME_SIZE;  // Continue to parse until we hit max size
-    ESP_LOGD(TAG, "User-defined function %02X found", function_code);
+    ESP_LOGD(TAG, "Unknown-length function %02X found", function_code);
   } else {
     if (crc16(&this->rx_buffer_[0], frame_length) != 0)
       return false;

esphome/components/modbus/modbus.h

@@ -82,7 +82,7 @@ class Modbus : public uart::UARTDevice, public Component {
   bool send_frame_(const ModbusFrame &frame);
   // Scans forward from min_length to find a frame boundary by CRC match for custom function codes.
   // Returns the matched frame length, or 0 if no valid CRC was found within MAX_FRAME_SIZE.
-  uint16_t find_custom_frame_end_(uint16_t min_length) const;
+  uint16_t find_frame_end_by_crc_(uint16_t min_length) const;
 
   uint32_t last_modbus_byte_{0};
   uint32_t last_receive_check_{0};

esphome/components/modbus/modbus_helpers.h

@@ -55,6 +55,38 @@ inline bool is_function_code_custom(uint8_t function_code) {
           masked_function_code <= FUNCTION_CODE_USER_DEFINED_SPACE_2_END);
 }
 
+/// True for any function code whose frame length the parsers cannot predict - everything the
+/// server_pdu_length()/client_pdu_length() switches fall through to `default` on (keep the case list
+/// in step with those switches). Deliberately wider than is_function_code_custom(): the user-defined
+/// ranges are unknown to the parser too, but so are the assigned-but-unimplemented codes
+/// (READ_EXCEPTION_STATUS, DIAGNOSTICS, GET_COMM_EVENT_*, REPORT_SERVER_ID) and every unassigned value.
+/// The 0x80 exception flag is masked off first, so a frame with it set classifies by its base code -
+/// even though a spec exception reply has a known 2-byte PDU. That is deliberate, matching what
+/// is_function_code_custom() has always done: some vendors use codes with the 0x80 bit set as ordinary
+/// codes with longer payloads, so the response parser CRC-scans these rather than assuming the spec
+/// length. For an intact spec exception the scan matches at its first candidate, so only a corrupt one
+/// pays (recovery by timeout instead of an immediate CRC failure).
+inline bool is_function_code_unknown_length(uint8_t function_code) {
+  switch (static_cast<FunctionCode>(function_code & FUNCTION_CODE_MASK)) {
+    case FunctionCode::READ_COILS:
+    case FunctionCode::READ_DISCRETE_INPUTS:
+    case FunctionCode::READ_HOLDING_REGISTERS:
+    case FunctionCode::READ_INPUT_REGISTERS:
+    case FunctionCode::WRITE_SINGLE_COIL:
+    case FunctionCode::WRITE_SINGLE_REGISTER:
+    case FunctionCode::WRITE_MULTIPLE_COILS:
+    case FunctionCode::WRITE_MULTIPLE_REGISTERS:
+    case FunctionCode::READ_FILE_RECORD:
+    case FunctionCode::WRITE_FILE_RECORD:
+    case FunctionCode::MASK_WRITE_REGISTER:
+    case FunctionCode::READ_WRITE_MULTIPLE_REGISTERS:
+    case FunctionCode::READ_FIFO_QUEUE:
+      return false;
+    default:
+      return true;
+  }
+}
+
 // Returns the expected length of a server response PDU based on the function code.
 // If too few bytes have arrived to determine the length, returns the minimum length. `size` is the
 // number of bytes available so far, which may exceed the eventual PDU (e.g. include the frame's CRC

esphome/components/pca6416a/__init__.py

@@ -1,6 +1,6 @@
 from esphome import pins
 import esphome.codegen as cg
-from esphome.components import i2c
+from esphome.components import gpio_expander, i2c
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_ID,
@@ -29,7 +29,7 @@ CONFIG_SCHEMA = (
     cv.Schema(
         {
             cv.Required(CONF_ID): cv.declare_id(PCA6416AComponent),
-            cv.Optional(CONF_INTERRUPT_PIN): pins.internal_gpio_input_pin_schema,
+            cv.Optional(CONF_INTERRUPT_PIN): gpio_expander.validate_interrupt_pin,
         }
     )
     .extend(cv.COMPONENT_SCHEMA)

esphome/components/pca9554/__init__.py

@@ -1,6 +1,6 @@
 from esphome import pins
 import esphome.codegen as cg
-from esphome.components import i2c
+from esphome.components import gpio_expander, i2c
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_ID,
@@ -30,7 +30,7 @@ CONFIG_SCHEMA = (
         {
             cv.Required(CONF_ID): cv.declare_id(PCA9554Component),
             cv.Optional(CONF_PIN_COUNT, default=8): cv.one_of(4, 8, 16),
-            cv.Optional(CONF_INTERRUPT_PIN): pins.internal_gpio_input_pin_schema,
+            cv.Optional(CONF_INTERRUPT_PIN): gpio_expander.validate_interrupt_pin,
         }
     )
     .extend(cv.COMPONENT_SCHEMA)

esphome/components/pcf8574/__init__.py

@@ -1,6 +1,6 @@
 from esphome import pins
 import esphome.codegen as cg
-from esphome.components import i2c
+from esphome.components import gpio_expander, i2c
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_ID,
@@ -28,7 +28,7 @@ CONFIG_SCHEMA = (
         {
             cv.Required(CONF_ID): cv.declare_id(PCF8574Component),
             cv.Optional(CONF_PCF8575, default=False): cv.boolean,
-            cv.Optional(CONF_INTERRUPT_PIN): pins.internal_gpio_input_pin_schema,
+            cv.Optional(CONF_INTERRUPT_PIN): gpio_expander.validate_interrupt_pin,
         }
     )
     .extend(cv.COMPONENT_SCHEMA)

esphome/components/pi4ioe5v6408/__init__.py

@@ -1,6 +1,6 @@
 from esphome import pins
 import esphome.codegen as cg
-from esphome.components import i2c
+from esphome.components import gpio_expander, i2c
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_ID,
@@ -34,7 +34,7 @@ CONFIG_SCHEMA = (
         {
             cv.Required(CONF_ID): cv.declare_id(PI4IOE5V6408Component),
             cv.Optional(CONF_RESET, default=True): cv.boolean,
-            cv.Optional(CONF_INTERRUPT_PIN): pins.internal_gpio_input_pin_schema,
+            cv.Optional(CONF_INTERRUPT_PIN): gpio_expander.validate_interrupt_pin,
         }
     )
     .extend(cv.COMPONENT_SCHEMA)

esphome/components/rp2040_pio_led_strip/led_strip.cpp

@@ -107,10 +107,10 @@ void RP2040PIOLEDStripLightOutput::setup() {
                           pio_get_dreq(this->pio_, this->sm_, true));  // set the DREQ to the state machine's TX FIFO
 
   dma_channel_configure(this->dma_chan_, &this->dma_config_,
-                        &this->pio_->txf[this->sm_],                     // write to the state machine's TX FIFO
-                        this->buf_,                                      // read from memory
-                        this->is_rgbw_ ? num_leds_ * 4 : num_leds_ * 3,  // number of bytes to transfer
-                        false                                            // don't start yet
+                        &this->pio_->txf[this->sm_],  // write to the state machine's TX FIFO
+                        this->buf_,                   // read from memory
+                        this->get_buffer_size_(),     // number of bytes to transfer
+                        false                         // don't start yet
   );
 
   // Initialize the semaphore for this DMA channel
@@ -142,58 +142,25 @@ void RP2040PIOLEDStripLightOutput::write_state(light::LightState *state) {
 }
 
 light::ESPColorView RP2040PIOLEDStripLightOutput::get_view_internal(int32_t index) const {
-  int32_t r = 0, g = 0, b = 0;
-  switch (this->rgb_order_) {
-    case ORDER_RGB:
-      r = 0;
-      g = 1;
-      b = 2;
-      break;
-    case ORDER_RBG:
-      r = 0;
-      g = 2;
-      b = 1;
-      break;
-    case ORDER_GRB:
-      r = 1;
-      g = 0;
-      b = 2;
-      break;
-    case ORDER_GBR:
-      r = 2;
-      g = 0;
-      b = 1;
-      break;
-    case ORDER_BGR:
-      r = 2;
-      g = 1;
-      b = 0;
-      break;
-    case ORDER_BRG:
-      r = 1;
-      g = 2;
-      b = 0;
-      break;
-  }
-  uint8_t multiplier = this->is_rgbw_ ? 4 : 3;
-  return {this->buf_ + (index * multiplier) + r,
-          this->buf_ + (index * multiplier) + g,
-          this->buf_ + (index * multiplier) + b,
-          this->is_rgbw_ ? this->buf_ + (index * multiplier) + 3 : nullptr,
+  const light::ChannelColors &colors = this->channel_colors_;
+  uint8_t *led = this->buf_ + (index * colors.bytes_per_led());
+  return {led + colors.r,
+          led + colors.g,
+          led + colors.b,
+          colors.has_white() ? led + colors.w : nullptr,
           &this->effect_data_[index],
           &this->correction_};
 }
 
 void RP2040PIOLEDStripLightOutput::dump_config() {
+  char channel_colors[5];
   ESP_LOGCONFIG(TAG,
                 "RP2040 PIO LED Strip Light Output:\n"
                 "  Pin: GPIO%d\n"
                 "  Number of LEDs: %d\n"
-                "  RGBW: %s\n"
-                "  RGB Order: %s\n"
+                "  Channel colors: %s\n"
                 "  Max Refresh Rate: %f Hz",
-                this->pin_, this->num_leds_, YESNO(this->is_rgbw_), rgb_order_to_string(this->rgb_order_),
-                this->max_refresh_rate_);
+                this->pin_, this->num_leds_, this->channel_colors_.to_string(channel_colors), this->max_refresh_rate_);
 }
 
 float RP2040PIOLEDStripLightOutput::get_setup_priority() const { return setup_priority::HARDWARE; }

esphome/components/rp2040_pio_led_strip/led_strip.h

@@ -7,6 +7,7 @@
 #include "esphome/core/helpers.h"
 
 #include "esphome/components/light/addressable_light.h"
+#include "esphome/components/light/channel_colors.h"
 #include "esphome/components/light/light_output.h"
 
 #include <hardware/dma.h>
@@ -18,15 +19,6 @@
 
 namespace esphome::rp2040_pio_led_strip {
 
-enum RGBOrder : uint8_t {
-  ORDER_RGB,
-  ORDER_RBG,
-  ORDER_GRB,
-  ORDER_GBR,
-  ORDER_BGR,
-  ORDER_BRG,
-};
-
 enum Chipset : uint8_t {
   CHIPSET_WS2812,
   CHIPSET_WS2812B,
@@ -36,25 +28,6 @@ enum Chipset : uint8_t {
   CHIPSET_CUSTOM = 0xFF,
 };
 
-inline const char *rgb_order_to_string(RGBOrder order) {
-  switch (order) {
-    case ORDER_RGB:
-      return "RGB";
-    case ORDER_RBG:
-      return "RBG";
-    case ORDER_GRB:
-      return "GRB";
-    case ORDER_GBR:
-      return "GBR";
-    case ORDER_BGR:
-      return "BGR";
-    case ORDER_BRG:
-      return "BRG";
-    default:
-      return "UNKNOWN";
-  }
-}
-
 using init_fn = void (*)(PIO pio, uint sm, uint offset, uint pin, float freq);
 
 class RP2040PIOLEDStripLightOutput final : public light::AddressableLight {
@@ -66,13 +39,14 @@ class RP2040PIOLEDStripLightOutput final : public light::AddressableLight {
   int32_t size() const override { return this->num_leds_; }
   light::LightTraits get_traits() override {
     auto traits = light::LightTraits();
-    this->is_rgbw_ ? traits.set_supported_color_modes({light::ColorMode::RGB_WHITE, light::ColorMode::WHITE})
-                   : traits.set_supported_color_modes({light::ColorMode::RGB});
+    this->channel_colors_.has_white()
+        ? traits.set_supported_color_modes({light::ColorMode::RGB_WHITE, light::ColorMode::WHITE})
+        : traits.set_supported_color_modes({light::ColorMode::RGB});
     return traits;
   }
   void set_pin(uint8_t pin) { this->pin_ = pin; }
   void set_num_leds(uint32_t num_leds) { this->num_leds_ = num_leds; }
-  void set_is_rgbw(bool is_rgbw) { this->is_rgbw_ = is_rgbw; }
+  void set_channel_colors(light::ChannelColors channel_colors) { this->channel_colors_ = channel_colors; }
 
   void set_max_refresh_rate(float interval_us) { this->max_refresh_rate_ = interval_us; }
 
@@ -81,7 +55,6 @@ class RP2040PIOLEDStripLightOutput final : public light::AddressableLight {
   void set_init_function(init_fn init) { this->init_ = init; }
 
   void set_chipset(Chipset chipset) { this->chipset_ = chipset; };
-  void set_rgb_order(RGBOrder rgb_order) { this->rgb_order_ = rgb_order; }
   void clear_effect_data() override {
     for (int i = 0; i < this->size(); i++) {
       this->effect_data_[i] = 0;
@@ -93,7 +66,7 @@ class RP2040PIOLEDStripLightOutput final : public light::AddressableLight {
  protected:
   light::ESPColorView get_view_internal(int32_t index) const override;
 
-  size_t get_buffer_size_() const { return this->num_leds_ * (3 + this->is_rgbw_); }
+  size_t get_buffer_size_() const { return this->num_leds_ * this->channel_colors_.bytes_per_led(); }
 
   static void dma_write_complete_handler();
 
@@ -102,14 +75,13 @@ class RP2040PIOLEDStripLightOutput final : public light::AddressableLight {
 
   uint8_t pin_;
   uint32_t num_leds_;
-  bool is_rgbw_;
 
   pio_hw_t *pio_;
   uint sm_;
   uint dma_chan_;
   dma_channel_config dma_config_;
 
-  RGBOrder rgb_order_{ORDER_RGB};
+  light::ChannelColors channel_colors_{0, 1, 2, light::ChannelColors::NO_WHITE};
   Chipset chipset_{CHIPSET_CUSTOM};
 
   uint32_t last_refresh_{0};

esphome/components/rp2040_pio_led_strip/light.py

@@ -3,6 +3,7 @@ from dataclasses import dataclass
 from esphome import pins
 import esphome.codegen as cg
 from esphome.components import light, rp2
+from esphome.components.const import CONF_CHANNEL_COLORS
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_CHIPSET,
@@ -13,6 +14,7 @@ from esphome.const import (
     CONF_PIN,
     CONF_RGB_ORDER,
 )
+from esphome.types import ConfigType
 from esphome.util import _LOGGER
 
 
@@ -37,7 +39,7 @@ def get_nops(timing):
     return nops
 
 
-def generate_assembly_code(id, rgbw, t0h, t0l, t1h, t1l):
+def generate_assembly_code(id, t0h, t0l, t1h, t1l):
     """
     Generate assembly code with the given timing values.
     """
@@ -139,8 +141,6 @@ RP2040PIOLEDStripLightOutput = rp2040_pio_led_strip_ns.class_(
     "RP2040PIOLEDStripLightOutput", light.AddressableLight
 )
 
-RGBOrder = rp2040_pio_led_strip_ns.enum("RGBOrder")
-
 Chipset = rp2040_pio_led_strip_ns.enum("Chipset")
 
 CHIPSETS = {
@@ -159,15 +159,6 @@ class LEDStripTimings:
     T1L: int
 
 
-RGB_ORDERS = {
-    "RGB": RGBOrder.ORDER_RGB,
-    "RBG": RGBOrder.ORDER_RBG,
-    "GRB": RGBOrder.ORDER_GRB,
-    "GBR": RGBOrder.ORDER_GBR,
-    "BGR": RGBOrder.ORDER_BGR,
-    "BRG": RGBOrder.ORDER_BRG,
-}
-
 CHIPSET_TIMINGS = {
     "WS2812": LEDStripTimings(20, 40, 46, 34),
     "WS2812B": LEDStripTimings(23, 49, 46, 26),
@@ -199,10 +190,12 @@ CONFIG_SCHEMA = cv.All(
             cv.GenerateID(CONF_OUTPUT_ID): cv.declare_id(RP2040PIOLEDStripLightOutput),
             cv.Required(CONF_PIN): pins.internal_gpio_output_pin_number,
             cv.Required(CONF_NUM_LEDS): cv.positive_not_null_int,
-            cv.Required(CONF_RGB_ORDER): cv.enum(RGB_ORDERS, upper=True),
+            cv.Optional(CONF_CHANNEL_COLORS): light.validate_channel_colors,
+            # Deprecated in favour of CONF_CHANNEL_COLORS, remove in 2027.3.0
+            cv.Optional(CONF_RGB_ORDER): cv.one_of(*light.RGB_ORDERS, upper=True),
+            cv.Optional(CONF_IS_RGBW): cv.boolean,
             cv.Required(CONF_PIO): cv.one_of(0, 1, int=True),
             cv.Optional(CONF_CHIPSET): cv.enum(CHIPSETS, upper=True),
-            cv.Optional(CONF_IS_RGBW, default=False): cv.boolean,
             cv.Inclusive(
                 CONF_BIT0_HIGH,
                 "custom",
@@ -222,10 +215,13 @@ CONFIG_SCHEMA = cv.All(
         }
     ),
     cv.has_exactly_one_key(CONF_CHIPSET, CONF_BIT0_HIGH),
+    light.migrate_channel_colors(
+        removed_in="2027.3.0", component="rp2040_pio_led_strip"
+    ),
 )
 
 
-async def to_code(config):
+async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_OUTPUT_ID])
     id = config[CONF_ID].id
     await light.register_light(var, config)
@@ -234,8 +230,9 @@ async def to_code(config):
     cg.add(var.set_num_leds(config[CONF_NUM_LEDS]))
     cg.add(var.set_pin(config[CONF_PIN]))
 
-    cg.add(var.set_rgb_order(config[CONF_RGB_ORDER]))
-    cg.add(var.set_is_rgbw(config[CONF_IS_RGBW]))
+    cg.add(
+        var.set_channel_colors(light.channel_colors_struct(config[CONF_CHANNEL_COLORS]))
+    )
 
     cg.add(var.set_pio(config[CONF_PIO]))
     cg.add(var.set_program(cg.RawExpression(f"&rp2040_pio_led_strip_{id}_program")))
@@ -255,7 +252,6 @@ async def to_code(config):
             key,
             generate_assembly_code(
                 id,
-                config[CONF_IS_RGBW],
                 CHIPSET_TIMINGS[chipset].T0H,
                 CHIPSET_TIMINGS[chipset].T0L,
                 CHIPSET_TIMINGS[chipset].T1H,
@@ -270,7 +266,6 @@ async def to_code(config):
             key,
             generate_assembly_code(
                 id,
-                config[CONF_IS_RGBW],
                 time_to_cycles(config[CONF_BIT0_HIGH]),
                 time_to_cycles(config[CONF_BIT0_LOW]),
                 time_to_cycles(config[CONF_BIT1_HIGH]),

esphome/components/runtime_image/__init__.py

@@ -5,6 +5,7 @@ from esphome.components.const import CONF_BYTE_ORDER
 from esphome.components.image import (
     IMAGE_TYPE,
     Image_,
+    validate_byte_order,
     validate_settings,
     validate_transparency,
     validate_type,
@@ -128,9 +129,7 @@ def runtime_image_schema(image_class: cg.MockObjClass = RuntimeImage) -> cv.Sche
             cv.Required(CONF_FORMAT): cv.one_of(*IMAGE_FORMATS, upper=True),
             cv.Optional(CONF_RESIZE): cv.dimensions,
             cv.Required(CONF_TYPE): validate_type(IMAGE_TYPE),
-            cv.Optional(CONF_BYTE_ORDER): cv.one_of(
-                "BIG_ENDIAN", "LITTLE_ENDIAN", upper=True
-            ),
+            cv.Optional(CONF_BYTE_ORDER): validate_byte_order,
             cv.Optional(CONF_TRANSPARENCY, default="OPAQUE"): validate_transparency(),
             cv.Optional(CONF_PLACEHOLDER): cv.use_id(Image_),
         }

esphome/components/socket/lwip_raw_tcp_impl.cpp

@@ -45,6 +45,11 @@ namespace esphome::socket {
 
 static const char *const TAG = "socket";
 
+#ifdef USE_ESP8266
+// optimistic_yield() rate limit in microseconds of CONT time; cheap when hot.
+static constexpr uint32_t ESP8266_YIELD_INTERVAL_US = 1000;
+#endif
+
 // set to 1 to enable verbose lwip logging
 #if 0  // NOLINT(readability-avoid-unconditional-preprocessor-if)
 #define LWIP_LOG(msg, ...) ESP_LOGVV(TAG, "socket %p: " msg, this, ##__VA_ARGS__)
@@ -535,6 +540,14 @@ ssize_t LWIPRawImpl::read_locked_(void *buf, size_t len) {
 }
 
 ssize_t LWIPRawImpl::read(void *buf, size_t len) {
+#ifdef USE_ESP8266
+  // Would block: yield to SYS so queued WiFi RX reaches lwip and this read
+  // may succeed. Without this, inbound segments can sit unprocessed for
+  // seconds while the main loop polls (CONT/SYS are cooperative on ESP8266).
+  if (this->waiting_for_data_()) {
+    optimistic_yield(ESP8266_YIELD_INTERVAL_US);
+  }
+#endif
   // See waiting_for_data_() for safety of unlocked reads.
   if (this->recv_timeout_cs_ > 0 && this->waiting_for_data_()) {
     this->wait_for_data_();
@@ -545,6 +558,8 @@ ssize_t LWIPRawImpl::read(void *buf, size_t len) {
 }
 
 ssize_t LWIPRawImpl::readv(const struct iovec *iov, int iovcnt) {
+  // No ESP8266 SYS yield here: only read() needs it today. If a consumer
+  // switches to scatter-gather reads, mirror the yield from read().
   // See waiting_for_data_() for safety of unlocked reads.
   if (this->recv_timeout_cs_ > 0 && this->waiting_for_data_()) {
     this->wait_for_data_();
@@ -609,19 +624,24 @@ int LWIPRawImpl::internal_output_() {
   }
   LWIP_LOG("tcp_output(%p)", this->pcb_);
   err_t err = tcp_output(this->pcb_);
-  if (err == ERR_ABRT) {
-    // sometimes lwip returns ERR_ABRT for no apparent reason
-    // the connection works fine afterwards, and back with ESPAsyncTCP we
-    // indirectly also ignored this error
-    // FIXME: figure out where this is returned and what it means in this context
-    LWIP_LOG("  -> err ERR_ABRT");
-    return 0;
-  }
   if (err != ERR_OK) {
     LWIP_LOG("  -> err %d", err);
-    errno = ECONNRESET;
-    return -1;
+    // ERR_ABRT: sometimes lwip returns it for no apparent reason; the
+    // connection works fine afterwards, and back with ESPAsyncTCP we
+    // indirectly also ignored this error, so treat it as success for
+    // flush purposes too.
+    // FIXME: figure out where this is returned and what it means in this context
+    if (err != ERR_ABRT) {
+      errno = ECONNRESET;
+      return -1;
+    }
   }
+#ifdef USE_ESP8266
+  // Flushed: yield to SYS so the queued segments reach the WiFi driver
+  // instead of waiting seconds for an unrelated SYS slot. Callers only get
+  // here after a successful tcp_write, so idle paths never yield.
+  optimistic_yield(ESP8266_YIELD_INTERVAL_US);
+#endif
   return 0;
 }
 

esphome/components/tca9555/__init__.py

@@ -1,6 +1,6 @@
 from esphome import pins
 import esphome.codegen as cg
-from esphome.components import i2c
+from esphome.components import gpio_expander, i2c
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_ID,
@@ -28,7 +28,7 @@ CONFIG_SCHEMA = (
     cv.Schema(
         {
             cv.Required(CONF_ID): cv.declare_id(TCA9555Component),
-            cv.Optional(CONF_INTERRUPT_PIN): pins.internal_gpio_input_pin_schema,
+            cv.Optional(CONF_INTERRUPT_PIN): gpio_expander.validate_interrupt_pin,
         }
     )
     .extend(cv.COMPONENT_SCHEMA)

esphome/components/web_server/__init__.py

@@ -11,6 +11,7 @@ from esphome.components.logger import request_log_listener
 from esphome.components.web_server_base import CONF_WEB_SERVER_BASE_ID
 import esphome.config_validation as cv
 from esphome.const import (
+    CONF_AP,
     CONF_AUTH,
     CONF_COMPRESSION,
     CONF_CSS_INCLUDE,
@@ -22,15 +23,19 @@ from esphome.const import (
     CONF_JS_URL,
     CONF_LOCAL,
     CONF_LOG,
+    CONF_MANUAL_IP,
     CONF_NAME,
+    CONF_NETWORKS,
     CONF_OTA,
     CONF_PASSWORD,
     CONF_PORT,
+    CONF_STATIC_IP,
     CONF_TYPE,
     CONF_USERNAME,
     CONF_VERSION,
     CONF_WEB_SERVER,
     CONF_WEB_SERVER_ID,
+    CONF_WIFI,
     PLATFORM_BK72XX,
     PLATFORM_ESP32,
     PLATFORM_ESP8266,
@@ -44,7 +49,23 @@ from esphome.types import ConfigType
 
 _LOGGER = logging.getLogger(__name__)
 
-AUTO_LOAD = ["json", "web_server_base"]
+
+def AUTO_LOAD() -> list[str]:
+    # No config parameter on purpose: that would make this a late (dynamic) auto-load and
+    # ota.web_server's dependency on web_server_base would not be satisfied in time.
+    auto_load = ["json", "web_server_base"]
+    # The AP mode DNS server (web_server_base/dns_server_esp32_idf) uses socket; only
+    # configs with a WiFi access point can end up in AP mode. CORE.raw_config is set
+    # after package merging, so a wifi block from a package is visible here.
+    wifi = CORE.raw_config.get(CONF_WIFI) if CORE.raw_config else None
+    if (
+        CORE.is_esp32
+        and wifi is not None
+        and (not isinstance(wifi, dict) or CONF_AP in wifi)
+    ):
+        auto_load.append("socket")
+    return auto_load
+
 
 AUTH_TYPE_BASIC = "basic"
 AUTH_TYPE_DIGEST = "digest"
@@ -203,9 +224,6 @@ def _final_validate_sorting(config: ConfigType) -> None:
         )
 
 
-FINAL_VALIDATE_SCHEMA = _final_validate_sorting
-
-
 def _consume_web_server_sockets(config: ConfigType) -> ConfigType:
     """Register socket needs for web_server component."""
     from esphome.components import socket
@@ -332,6 +350,95 @@ async def add_entity_config(entity, config):
     )
 
 
+def wifi_is_ap_only(wifi_config: ConfigType | None) -> bool:
+    """AP only: an access point and no network to join, so the device is only ever reached
+    through its own AP."""
+    return (
+        wifi_config is not None
+        and CONF_AP in wifi_config
+        and not wifi_config.get(CONF_NETWORKS)
+    )
+
+
+def serve_local(config: ConfigType, wifi_config: ConfigType | None) -> bool:
+    """Embed the interface unless ``local:`` says otherwise; AP only WiFi has no internet
+    for the hosted page. Version 1 has no local mode."""
+    if (local := config.get(CONF_LOCAL)) is not None:
+        return local
+    return config[CONF_VERSION] != 1 and wifi_is_ap_only(wifi_config)
+
+
+def serve_captive(config: ConfigType, full_config: ConfigType) -> bool:
+    """web_server runs its own captive portal while the AP is up: embedded interface plus
+    an access point, unless captive_portal (which owns that role) is configured. Only on
+    port 80: the OS captive portal probes and the DHCP portal URI always use port 80, so
+    a portal on another port could never be discovered."""
+    wifi_config = full_config.get(CONF_WIFI)
+    return (
+        "captive_portal" not in full_config
+        and config[CONF_PORT] == 80
+        and wifi_config is not None
+        and CONF_AP in wifi_config
+        and serve_local(config, wifi_config)
+    )
+
+
+def _final_validate_ap_mode(config: ConfigType) -> None:
+    full_config = fv.full_config.get()
+    wifi_config = full_config.get(CONF_WIFI)
+    captive = serve_captive(config, full_config)
+    local = serve_local(config, wifi_config)
+    if captive:
+        web_server_base.consume_captive_dns_sockets(config, "web_server")
+    # Surface behavior that the config does not spell out.
+    if local and CONF_LOCAL not in config:
+        _LOGGER.info(
+            "WiFi is AP only: embedding the web interface in the firmware "
+            "(local: true, roughly 13 KB of flash for version 2, 78 KB for version 3)%s. "
+            "Set 'local: false' to load it from the internet instead.",
+            " and serving it as a captive portal on the access point"
+            if captive
+            else "",
+        )
+    elif captive:
+        _LOGGER.info(
+            "web_server will act as a captive portal while the %saccess point is active.",
+            "" if wifi_is_ap_only(wifi_config) else "fallback ",
+        )
+    if not wifi_is_ap_only(wifi_config):
+        return
+    if not local:
+        _LOGGER.warning(
+            "WiFi is AP only and the web_server interface is loaded from the internet, "
+            "which browsers on the access point usually cannot reach; the page stays "
+            "blank. %s so the interface is embedded in the firmware.",
+            "Remove 'local: false'"
+            if config.get(CONF_LOCAL) is False
+            else "Migrate to version 2 or 3",
+        )
+    elif config[CONF_PORT] != 80:
+        ap_ip = "192.168.4.1"
+        if (manual_ip := wifi_config[CONF_AP].get(CONF_MANUAL_IP)) is not None:
+            ap_ip = str(manual_ip[CONF_STATIC_IP])
+        _LOGGER.warning(
+            "WiFi is AP only and web_server uses port %d. The interface cannot open "
+            "automatically on the access point (captive portal detection only works on "
+            "port 80); open http://%s:%d/ manually, or remove 'port:' to use 80.",
+            config[CONF_PORT],
+            ap_ip,
+            config[CONF_PORT],
+        )
+
+
+def _final_validate(config: ConfigType) -> None:
+    # Called one after the other rather than via cv.All: these return None.
+    _final_validate_sorting(config)
+    _final_validate_ap_mode(config)
+
+
+FINAL_VALIDATE_SCHEMA = _final_validate
+
+
 def build_index_html(config) -> str:
     html = "<!DOCTYPE html><html><head><meta charset=UTF-8><link rel=icon href=data:>"
     css_include = config.get(CONF_CSS_INCLUDE)
@@ -432,8 +539,12 @@ async def to_code(config):
         with path.open(encoding="utf-8") as js_file:
             add_resource_as_progmem("JS_INCLUDE", js_file.read())
     cg.add(var.set_include_internal(config[CONF_INCLUDE_INTERNAL]))
-    if CONF_LOCAL in config and config[CONF_LOCAL]:
+    if serve_local(config, CORE.config.get(CONF_WIFI)):
         cg.add_define("USE_WEBSERVER_LOCAL")
+    if serve_captive(config, CORE.config):
+        # AP mode: DNS server plus redirect of unknown URLs so phones open the interface
+        cg.add_define("USE_WEBSERVER_CAPTIVE")
+        web_server_base.add_captive_dns_library()
     if config[CONF_COMPRESSION] == "gzip":
         cg.add_define("USE_WEBSERVER_GZIP")
 

esphome/components/web_server/web_server.cpp

@@ -44,6 +44,10 @@
 #include "esphome/components/radio_frequency/radio_frequency.h"
 #endif
 
+#ifdef USE_WEBSERVER_CAPTIVE
+#include "esphome/components/wifi/wifi_component.h"
+#endif
+
 #ifdef USE_WEBSERVER_LOCAL
 #if USE_WEBSERVER_VERSION == 2
 #include "server_index_v2.h"
@@ -340,7 +344,15 @@ void DeferredUpdateEventSourceList::on_client_disconnect_(DeferredUpdateEventSou
 }
 #endif
 
-WebServer::WebServer(web_server_base::WebServerBase *base) : base_(base) {}
+#ifdef USE_WEBSERVER_CAPTIVE
+WebServer *global_web_server = nullptr;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+#endif
+
+WebServer::WebServer(web_server_base::WebServerBase *base) : base_(base) {
+#ifdef USE_WEBSERVER_CAPTIVE
+  global_web_server = this;
+#endif
+}
 
 #ifdef USE_WEBSERVER_CSS_INCLUDE
 void WebServer::set_css_include(const char *css_include) { this->css_include_ = css_include; }
@@ -386,6 +398,11 @@ void WebServer::setup() {
   this->base_->add_handler(&this->events_);
 #endif
   this->base_->add_handler(this);
+#ifdef USE_WEBSERVER_CAPTIVE
+  // Not-found fallback (outside the auth middleware): the OS captive portal probes hit
+  // arbitrary URLs and must get the redirect without credentials.
+  this->base_->get_server()->onNotFound([this](AsyncWebServerRequest *request) { this->handle_not_found_(request); });
+#endif
 
   // OTA is now handled by the web_server OTA platform
 
@@ -401,16 +418,52 @@ void WebServer::setup() {
   });
 }
 void WebServer::loop() {
-  // No SSE clients connected; stop looping until a new client connects via
+  bool keep_looping = this->events_.loop();
+#ifdef USE_WEBSERVER_CAPTIVE
+  this->dns_.loop();
+  keep_looping |= this->dns_.is_running();
+#endif
+  // No SSE clients connected (and no captive DNS to serve); stop looping until a new client connects via
   // enable_loop_soon_any_context(). This is safe because:
   // - set_interval/set_timeout/defer run via the Scheduler, independent of loop()
   // - deferrable_send_state early-outs when no clients are connected
   // - try_send_nodefer (log, ping) iterates sessions which are empty
   // - REST API handlers use defer() which runs via the Scheduler
-  if (!this->events_.loop())
+  if (!keep_looping)
     this->disable_loop();
 }
 
+#ifdef USE_WEBSERVER_CAPTIVE
+void WebServer::start_captive() {
+  // CaptiveDNS::start() no-ops too; this guard just avoids repeating the log and enable_loop
+  if (this->dns_.is_running())
+    return;
+  network::IPAddress ip = wifi::global_wifi_component->wifi_soft_ap_ip();
+  this->dns_.start(ip);
+  this->enable_loop();
+  char ip_buf[network::IP_ADDRESS_BUFFER_SIZE];
+  ESP_LOGI(TAG, "AP mode: serving the web interface as captive portal at http://%s/", ip.str_to(ip_buf));
+}
+
+void WebServer::end_captive() { this->dns_.stop(); }
+
+void WebServer::handle_not_found_(AsyncWebServerRequest *request) {
+  // OS captive portal probe (or any other unknown page) while the AP is up: send the browser
+  // to the real page. A redirect rather than the page itself, because the interface resolves
+  // its /events and REST paths relative to the page URL.
+  if (this->dns_.is_running() && request->method() == HTTP_GET) {
+    // Captive mode requires port 80 (enforced at validation), so no port suffix is needed.
+    char location[7 + network::IP_ADDRESS_BUFFER_SIZE + 1];
+    size_t pos = buf_append_str(location, sizeof(location), 0, "http://");
+    wifi::global_wifi_component->wifi_soft_ap_ip().str_to(location + pos);
+    buf_append_str(location, sizeof(location), strlen(location), "/");
+    request->redirect(location);
+    return;
+  }
+  request->send(404);
+}
+#endif
+
 #ifdef USE_LOGGER
 void WebServer::on_log(uint8_t level, const char *tag, const char *message, size_t message_len) {
   (void) level;

esphome/components/web_server/web_server.h

@@ -4,6 +4,9 @@
 
 #include "esphome/components/json/json_util.h"
 #include "esphome/components/web_server_base/web_server_base.h"
+#ifdef USE_WEBSERVER_CAPTIVE
+#include "esphome/components/web_server_base/captive_dns.h"
+#endif
 #ifdef USE_WEBSERVER
 #include "esphome/core/component.h"
 #include "esphome/core/controller.h"
@@ -276,6 +279,18 @@ class WebServer final : public Controller, public Component, public AsyncWebHand
   /// Handle an index request under '/'.
   void handle_index_request(AsyncWebServerRequest *request);
 
+#ifdef USE_WEBSERVER_CAPTIVE
+  /** AP mode: run a DNS server that answers every name with the AP address and redirect any
+   * unknown URL to the interface, so a phone joining the AP opens it through the OS captive
+   * portal check. Started and ended by the wifi component with the access point. start may run
+   * before setup() (wifi sets up first): safe because enable_loop() is a no-op before setup;
+   * nothing but the DNS server may be touched, in particular not base_ or the handlers.
+   */
+  void start_captive();
+  void end_captive();
+  bool is_captive() const { return this->dns_.is_running(); }
+#endif
+
   /// Return the webserver configuration as JSON.
   json::SerializationBuffer<> get_config_json();
 
@@ -597,6 +612,10 @@ class WebServer final : public Controller, public Component, public AsyncWebHand
 #elif USE_ARDUINO
   DeferredUpdateEventSourceList events_;
 #endif
+#ifdef USE_WEBSERVER_CAPTIVE
+  void handle_not_found_(AsyncWebServerRequest *request);
+  web_server_base::CaptiveDNS dns_;
+#endif
 
 #if USE_WEBSERVER_VERSION == 1
   const char *css_url_{nullptr};
@@ -696,5 +715,9 @@ class WebServer final : public Controller, public Component, public AsyncWebHand
 #endif
 };
 
+#ifdef USE_WEBSERVER_CAPTIVE
+extern WebServer *global_web_server;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+#endif
+
 }  // namespace esphome::web_server
 #endif

esphome/components/web_server_base/__init__.py

@@ -1,11 +1,13 @@
 from pathlib import Path
 
 import esphome.codegen as cg
+from esphome.config_helpers import filter_source_files_from_platform
 import esphome.config_validation as cv
-from esphome.const import CONF_ID
+from esphome.const import CONF_ID, PlatformFramework
 from esphome.core import CORE, coroutine_with_priority
 from esphome.coroutine import CoroPriority
 from esphome.helpers import copy_file_if_changed
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@esphome/core"]
 DEPENDENCIES = ["network"]
@@ -25,6 +27,22 @@ WebServerBase = web_server_base_ns.class_("WebServerBase")
 CONF_WEB_SERVER_BASE_ID = "web_server_base_id"
 
 
+def consume_captive_dns_sockets(config: ConfigType, name: str) -> None:
+    """Register the sockets a captive portal needs on top of the shared HTTP server:
+    1 UDP socket for the DNS server and 3 TCP sockets for the OS captive portal probes,
+    which make several requests that linger in TIME_WAIT."""
+    from esphome.components import socket
+
+    socket.consume_sockets(3, name)(config)
+    socket.consume_sockets(1, name, socket.SocketType.UDP)(config)
+
+
+def add_captive_dns_library() -> None:
+    """Pull in the Arduino DNSServer library used by CaptiveDNS off ESP32."""
+    if CORE.using_arduino and (CORE.is_esp8266 or CORE.is_libretiny or CORE.is_rp2):
+        cg.add_library("DNSServer", None)
+
+
 def _consume_web_server_base_sockets(config):
     """Register the shared listening socket for the HTTP server.
 
@@ -80,3 +98,15 @@ async def to_code(config):
             cg.add_platformio_option("extra_scripts", ["pre:fix_rp2040_hash.py"])
         # https://github.com/ESP32Async/ESPAsyncWebServer/blob/main/library.json
         cg.add_library("ESP32Async/ESPAsyncWebServer", "3.9.6")
+
+
+# The DNS server used for captive portals on ESP32; other platforms use the Arduino
+# DNSServer library. Its source is also guarded by USE_CAPTIVE_PORTAL / USE_WEBSERVER_CAPTIVE.
+FILTER_SOURCE_FILES = filter_source_files_from_platform(
+    {
+        "dns_server_esp32_idf.cpp": {
+            PlatformFramework.ESP32_ARDUINO,
+            PlatformFramework.ESP32_IDF,
+        },
+    }
+)

esphome/components/web_server_base/captive_dns.h

@@ -0,0 +1,58 @@
+#pragma once
+#include "esphome/core/defines.h"
+// DNS server that answers every name with the access point address, so a phone joining the
+// AP runs its captive portal check against the device. Shared by captive_portal and the
+// web_server AP mode; hides the ESP32 (own implementation) vs Arduino (DNSServer library) split.
+#if defined(USE_CAPTIVE_PORTAL) || defined(USE_WEBSERVER_CAPTIVE)
+#include <memory>
+
+#include "esphome/components/network/ip_address.h"
+#include "esphome/core/helpers.h"
+#include "esphome/core/progmem.h"
+#if defined(USE_ESP32)
+#include "dns_server_esp32_idf.h"
+#elif defined(USE_ARDUINO)
+#include <DNSServer.h>
+#endif
+
+namespace esphome::web_server_base {
+
+// The server object only exists while running, so an idle owner (AP not up) pays one pointer.
+class CaptiveDNS {
+ public:
+  void start(const network::IPAddress &ip) {
+    if (this->dns_server_ != nullptr)
+      return;
+    this->dns_server_ = make_unique<DNSServer>();
+#if defined(USE_ESP32)
+    this->dns_server_->start(ip);
+#elif defined(USE_ARDUINO)
+    this->dns_server_->setErrorReplyCode(DNSReplyCode::NoError);
+    this->dns_server_->start(53, ESPHOME_F("*"), ip);
+#endif
+  }
+  void stop() {
+    if (this->dns_server_ == nullptr)
+      return;
+    this->dns_server_->stop();
+    this->dns_server_ = nullptr;
+  }
+  /// Answer one pending query; call from the owner's loop() while running.
+  void loop() {
+    if (this->dns_server_ == nullptr)
+      return;
+#if defined(USE_ESP32)
+    this->dns_server_->process_next_request();
+#elif defined(USE_ARDUINO)
+    this->dns_server_->processNextRequest();
+#endif
+  }
+  bool is_running() const { return this->dns_server_ != nullptr; }
+
+ protected:
+  // ESP32: web_server_base::DNSServer from dns_server_esp32_idf.h; Arduino: the library class.
+  std::unique_ptr<DNSServer> dns_server_;
+};
+
+}  // namespace esphome::web_server_base
+#endif  // USE_CAPTIVE_PORTAL || USE_WEBSERVER_CAPTIVE

esphome/components/web_server_base/dns_server_esp32_idf.cpp

@@ -1,5 +1,5 @@
 #include "dns_server_esp32_idf.h"
-#ifdef USE_ESP32
+#if defined(USE_ESP32) && (defined(USE_CAPTIVE_PORTAL) || defined(USE_WEBSERVER_CAPTIVE))
 
 #include "esphome/core/log.h"
 #include "esphome/core/hal.h"
@@ -7,9 +7,9 @@
 #include <lwip/sockets.h>
 #include <lwip/inet.h>
 
-namespace esphome::captive_portal {
+namespace esphome::web_server_base {
 
-static const char *const TAG = "captive_portal.dns";
+static const char *const TAG = "web_server_base.dns";
 
 // DNS constants
 static constexpr uint16_t DNS_PORT = 53;
@@ -202,6 +202,6 @@ void DNSServer::process_next_request() {
   }
 }
 
-}  // namespace esphome::captive_portal
+}  // namespace esphome::web_server_base
 
-#endif  // USE_ESP32
+#endif  // USE_ESP32 && (USE_CAPTIVE_PORTAL || USE_WEBSERVER_CAPTIVE)

esphome/components/web_server_base/dns_server_esp32_idf.h

@@ -1,11 +1,15 @@
 #pragma once
-#ifdef USE_ESP32
+#include "esphome/core/defines.h"
+// Small DNS server that answers every query with the access point address, so a
+// phone joining the AP opens the captive portal or web_server page on its own.
+// Shared by captive_portal and the web_server AP mode.
+#if defined(USE_ESP32) && (defined(USE_CAPTIVE_PORTAL) || defined(USE_WEBSERVER_CAPTIVE))
 
 #include "esphome/core/helpers.h"
 #include "esphome/components/network/ip_address.h"
 #include "esphome/components/socket/socket.h"
 
-namespace esphome::captive_portal {
+namespace esphome::web_server_base {
 
 class DNSServer {
  public:
@@ -27,6 +31,6 @@ class DNSServer {
   uint8_t buffer_[DNS_BUFFER_SIZE];
 };
 
-}  // namespace esphome::captive_portal
+}  // namespace esphome::web_server_base
 
-#endif  // USE_ESP32
+#endif  // USE_ESP32 && (USE_CAPTIVE_PORTAL || USE_WEBSERVER_CAPTIVE)

esphome/components/web_server_idf/web_server_idf.cpp

@@ -325,9 +325,9 @@ StringRef AsyncWebServerRequest::url_to(std::span<char, URL_BUF_SIZE> buffer) co
   return StringRef(buffer.data(), decoded_len);
 }
 
-void AsyncWebServerRequest::redirect(const std::string &url) {
+void AsyncWebServerRequest::redirect(const char *url) {
   httpd_resp_set_status(*this, "302 Found");
-  httpd_resp_set_hdr(*this, "Location", url.c_str());
+  httpd_resp_set_hdr(*this, "Location", url);
   httpd_resp_set_hdr(*this, "Connection", "close");
   httpd_resp_send(*this, nullptr, 0);
 }

esphome/components/web_server_idf/web_server_idf.h

@@ -132,7 +132,8 @@ class AsyncWebServerRequest {
   void requestAuthentication() const;
 #endif
 
-  void redirect(const std::string &url);
+  void redirect(const char *url);
+  void redirect(const std::string &url) { this->redirect(url.c_str()); }
 
   inline void ESPHOME_ALWAYS_INLINE send(AsyncWebServerResponse *response) {
     httpd_resp_send(*this, response->get_content_data(), response->get_content_size());

esphome/components/wifi/wifi_component.cpp

@@ -36,6 +36,9 @@
 #ifdef USE_CAPTIVE_PORTAL
 #include "esphome/components/captive_portal/captive_portal.h"
 #endif
+#ifdef USE_WEBSERVER_CAPTIVE
+#include "esphome/components/web_server/web_server.h"
+#endif
 
 #ifdef USE_IMPROV
 #include "esphome/components/esp32_improv/esp32_improv_component.h"
@@ -728,9 +731,9 @@ void WiFiComponent::start() {
     if (captive_portal::global_captive_portal != nullptr) {
       this->wifi_sta_pre_setup_();
       this->start_scanning();
-      captive_portal::global_captive_portal->start();
     }
 #endif
+    this->start_ap_portal_();
 #endif  // USE_WIFI_AP
   }
 #ifdef USE_IMPROV
@@ -791,8 +794,8 @@ void WiFiComponent::loop() {
           this->check_connecting_finished(now);
           break;
         }
-        // Use longer cooldown when captive portal/improv is active to avoid disrupting user config
-        bool portal_active = this->is_captive_portal_active_() || this->is_esp32_improv_active_();
+        // Use longer cooldown when a portal/improv is active to avoid disrupting a user on the AP
+        bool portal_active = this->is_ap_portal_active_() || this->is_esp32_improv_active_();
         uint32_t cooldown_duration = portal_active ? WIFI_COOLDOWN_WITH_AP_ACTIVE_MS : WIFI_COOLDOWN_DURATION_MS;
         if (now - this->action_started_ > cooldown_duration) {
           // After cooldown we either restarted the adapter because of
@@ -861,13 +864,11 @@ void WiFiComponent::loop() {
         ESP_LOGI(TAG, "Starting fallback AP");
         this->setup_ap_config_();
 #ifdef USE_CAPTIVE_PORTAL
-        if (captive_portal::global_captive_portal != nullptr) {
-          // Reset so we force one full scan after captive portal starts
-          // (previous scans were filtered because captive portal wasn't active yet)
-          this->has_completed_scan_after_captive_portal_start_ = false;
-          captive_portal::global_captive_portal->start();
-        }
+        // Reset so we force one full scan after captive portal starts
+        // (previous scans were filtered because captive portal wasn't active yet)
+        this->has_completed_scan_after_captive_portal_start_ = false;
 #endif
+        this->start_ap_portal_();
       }
     }
 #endif  // USE_WIFI_AP
@@ -1618,10 +1619,8 @@ void WiFiComponent::check_connecting_finished(uint32_t now) {
     this->retry_phase_ = WiFiRetryPhase::INITIAL_CONNECT;
     this->num_retried_ = 0;
     if (this->has_ap()) {
-#ifdef USE_CAPTIVE_PORTAL
-      if (this->is_captive_portal_active_()) {
-        captive_portal::global_captive_portal->end();
-      }
+#ifdef USE_WIFI_AP
+      this->end_ap_portal_();
 #endif
       ESP_LOGD(TAG, "Disabling AP");
       this->wifi_mode_({}, false);
@@ -1948,10 +1947,10 @@ bool WiFiComponent::transition_to_phase_(WiFiRetryPhase new_phase) {
       break;
 
     case WiFiRetryPhase::RESTARTING_ADAPTER:
-      // Skip actual adapter restart if captive portal/improv is active
+      // Skip actual adapter restart if a portal/improv is active
       // This allows state machine to reset num_retried_ and trigger fresh scan
-      // without disrupting the captive portal/improv connection
-      if (!this->is_captive_portal_active_() && !this->is_esp32_improv_active_()) {
+      // without disrupting the portal/improv connection
+      if (!this->is_ap_portal_active_() && !this->is_esp32_improv_active_()) {
         this->restart_adapter();
       } else {
         // Even when skipping full restart, disconnect to clear driver state
@@ -2213,6 +2212,38 @@ bool WiFiComponent::is_captive_portal_active_() {
   return false;
 #endif
 }
+
+bool WiFiComponent::is_ap_portal_active_() {
+#ifdef USE_WEBSERVER_CAPTIVE
+  if (web_server::global_web_server->is_captive())
+    return true;
+#endif
+  return this->is_captive_portal_active_();
+}
+
+#ifdef USE_WIFI_AP
+// global_web_server needs no null check: codegen always instantiates WebServer when
+// USE_WEBSERVER_CAPTIVE is defined, and the constructor assigns the global.
+void WiFiComponent::start_ap_portal_() {
+#ifdef USE_CAPTIVE_PORTAL
+  if (captive_portal::global_captive_portal != nullptr)
+    captive_portal::global_captive_portal->start();
+#endif
+#ifdef USE_WEBSERVER_CAPTIVE
+  web_server::global_web_server->start_captive();
+#endif
+}
+
+void WiFiComponent::end_ap_portal_() {
+#ifdef USE_CAPTIVE_PORTAL
+  if (this->is_captive_portal_active_())
+    captive_portal::global_captive_portal->end();
+#endif
+#ifdef USE_WEBSERVER_CAPTIVE
+  web_server::global_web_server->end_captive();
+#endif
+}
+#endif  // USE_WIFI_AP
 bool WiFiComponent::is_esp32_improv_active_() {
 #ifdef USE_IMPROV
   return esp32_improv::global_improv_component != nullptr && esp32_improv::global_improv_component->is_active();

esphome/components/wifi/wifi_component.h

@@ -789,6 +789,12 @@ class WiFiComponent final : public Component {
   network::IPAddress wifi_dns_ip_(int num);
 
   bool is_captive_portal_active_();
+  /// captive_portal or the web_server AP mode is serving a user on the access point
+  bool is_ap_portal_active_();
+#ifdef USE_WIFI_AP
+  void start_ap_portal_();
+  void end_ap_portal_();
+#endif
   bool is_esp32_improv_active_();
 
 #ifdef USE_WIFI_FAST_CONNECT

esphome/components/wifi/wifi_component_esp_idf.cpp

@@ -1128,10 +1128,16 @@ bool WiFiComponent::wifi_ap_ip_config_(const optional<ManualIP> &manual_ip) {
     return false;
   }
 
-#if defined(USE_CAPTIVE_PORTAL) && ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(5, 4, 0)
-  // Configure DHCP Option 114 (Captive Portal URI) if captive portal is enabled
-  // This provides a standards-compliant way for clients to discover the captive portal
-  if (captive_portal::global_captive_portal != nullptr) {
+#if (defined(USE_CAPTIVE_PORTAL) || defined(USE_WEBSERVER_CAPTIVE)) && ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(5, 4, 0)
+  // Configure DHCP Option 114 (Captive Portal URI) if captive portal or the web_server AP
+  // mode is enabled. This provides a standards-compliant way for clients to discover the portal
+#ifdef USE_WEBSERVER_CAPTIVE
+  // web_server AP mode always serves the portal when compiled in
+  const bool has_portal = true;
+#else
+  const bool has_portal = captive_portal::global_captive_portal != nullptr;
+#endif
+  if (has_portal) {
     // Buffer must be static - dhcps_set_option_info stores pointer, doesn't copy
     static char captive_portal_uri[24];        // "http://" (7) + IPv4 max (15) + null
     memcpy(captive_portal_uri, "http://", 7);  // NOLINT(bugprone-not-null-terminated-result) - str_to null-terminates

esphome/config.py

@@ -620,6 +620,23 @@ class LoadValidationStep(ConfigValidationStep):
             elif not isinstance(self.conf, list):
                 result[self.domain] = self.conf = [self.conf]
 
+            # Permanent expansion hook: a platform-tagged entry may expand into
+            # several (e.g. `image`'s `defaults:`/`files:`), for `platform:`-tagged dicts only.
+            if (expand := component.expand_platform_config) is not None and all(
+                isinstance(entry, dict) and CONF_PLATFORM in entry
+                for entry in self.conf
+            ):
+                with result.catch_error(path):
+                    expanded = expand(self.conf)
+                    if not isinstance(expanded, list):
+                        # A non-list return is a component bug (not a user error):
+                        # raise explicitly (survives -O/-OO) so it escapes catch_error.
+                        raise TypeError(
+                            f"{self.domain}: EXPAND_PLATFORM_CONFIG must "
+                            f"return a list, got {type(expanded).__name__}"
+                        )
+                    result[self.domain] = self.conf = expanded
+
         # Process AUTO_LOAD
         _process_auto_load(result, component, path)
 

esphome/core/defines.h

@@ -353,6 +353,7 @@
 #define USE_WEBSERVER
 #define USE_WEBSERVER_AUTH
 #define USE_WEBSERVER_AUTH_DIGEST
+#define USE_WEBSERVER_CAPTIVE
 #define USE_WEBSERVER_OTA
 #define USE_WEBSERVER_PORT 80  // NOLINT
 #define USE_WEBSERVER_GZIP
@@ -466,6 +467,7 @@
 #define USE_WEBSERVER
 #define USE_WEBSERVER_AUTH
 #define USE_WEBSERVER_AUTH_DIGEST
+#define USE_WEBSERVER_CAPTIVE
 #define USE_WEBSERVER_PORT 80  // NOLINT
 #endif
 
@@ -523,6 +525,7 @@
 #define USE_WEBSERVER
 #define USE_WEBSERVER_AUTH
 #define USE_WEBSERVER_AUTH_DIGEST
+#define USE_WEBSERVER_CAPTIVE
 #define USE_WEBSERVER_PORT 80  // NOLINT
 #define USE_ESPHOME_TASK_LOG_BUFFER
 #define ESPHOME_TASK_LOG_BUFFER_SIZE 768

esphome/loader.py

@@ -164,6 +164,14 @@ class ComponentManifest:
         """
         return getattr(self.module, "LEGACY_CONFIG_MIGRATE", None)
 
+    @property
+    def expand_platform_config(
+        self,
+    ) -> Callable[[list[ConfigType]], list[ConfigType]] | None:
+        """Optional `EXPAND_PLATFORM_CONFIG` callable; runs on the normalized `platform:`-tagged
+        entry list before per-entry CONFIG_SCHEMA. Must return a list (raise `cv.Invalid` for user errors)."""
+        return getattr(self.module, "EXPAND_PLATFORM_CONFIG", None)
+
     @property
     def resources(self) -> list[FileResource]:
         """Return a list of all file resources defined in the package of this component.

esphome/platformio/ccache.py.script

@@ -1,5 +1,4 @@
 import os
-import shutil
 
 # pylint: disable=E0602
 Import("env")  # noqa
@@ -9,15 +8,17 @@ Import("env")  # noqa
 # esphome/platformio/toolchain.py); this script only supplies the SCons-level
 # mechanism.
 #
+# The binary comes pre-resolved in ESPHOME_CCACHE_PATH; _ccache_env() has
+# already stripped the Windows \\?\ prefix that cmd.exe cannot run.
+#
 # This is a "pre" script, so the platform's builder (which sets CC/CXX and
 # clones the construction environment for framework and library builds) runs
 # after it. Replacing CC/CXX here would be overwritten, and replacing them in
 # a "post" script would miss the already-cloned library environments. Wrapping
 # SPAWN instead is ordering-proof: clones copy the wrapper, and every compiler
 # invocation from every environment funnels through it at execution time.
-if (
-    os.environ.get("ESPHOME_CCACHE_ENABLE") == "1"
-    and (ccache_path := shutil.which("ccache")) is not None
+if os.environ.get("ESPHOME_CCACHE_ENABLE") == "1" and (
+    ccache_path := os.environ.get("ESPHOME_CCACHE_PATH")
 ):
     original_spawn = env["SPAWN"]
 

esphome/platformio/toolchain.py

@@ -60,6 +60,9 @@ def _strip_win_long_path_prefix(path: str) -> str:
     "The system cannot find the path specified." Stripping the prefix early
     keeps the path shell-quotable.
 
+    Also applied to the ccache path exported by ``_ccache_env()``, which
+    ``shutil.which`` can return with the same prefix.
+
     No-op on non-Windows platforms.
     """
     if sys.platform != "win32":
@@ -235,8 +238,8 @@ def _check_platformio_python_stamp(config: "ProjectConfig") -> None:
         _write_pio_stamp_python(stamp_file, current)
 
 
-def _ccache_usable() -> bool:
-    """Return True when the ``ccache`` on PATH actually runs.
+def _ccache_runs(ccache: str) -> bool:
+    """Return True when the ``ccache`` found on PATH actually runs.
 
     ``shutil.which`` proves existence, not runnability: on Windows it also
     matches ``.bat``/``.cmd`` wrappers and stale package-manager shims whose
@@ -244,9 +247,6 @@ def _ccache_usable() -> bool:
     step with an opaque OS error, so probe once and fall back to compiling
     without ccache when the probe fails.
     """
-    ccache = shutil.which("ccache")
-    if ccache is None:
-        return False
     try:
         subprocess.run(
             [ccache, "--version"],
@@ -265,14 +265,29 @@ def _ccache_usable() -> bool:
 
 
 def _ccache_env() -> dict[str, str]:
-    """Return ccache settings for PlatformIO builds.
+    r"""Return ccache settings for PlatformIO builds.
 
     Enabled by default whenever the ``ccache`` binary is on PATH; set
     ``ESPHOME_CCACHE_ENABLE=0`` in the environment to opt out (or ``1`` to
-    force it on). The decision is normalized into ``ESPHOME_CCACHE_ENABLE``
-    so platform build scripts (e.g. the esp8266 ``ccache.py`` extra script,
-    which wraps compiler invocations inside SCons) only have to check for
-    ``"1"`` instead of re-implementing the policy.
+    force it on without the runnability probe; a binary is still needed).
+    The decision is normalized into ``ESPHOME_CCACHE_ENABLE`` and the
+    binary's location into ``ESPHOME_CCACHE_PATH`` so platform build scripts
+    (the shared ``ccache.py`` extra script, which wraps compiler invocations
+    inside SCons) only have to check for ``"1"`` and use the path as given
+    instead of re-implementing the policy.
+
+    The path is exported rather than looked up again inside SCons because
+    ``shutil.which`` can return a Windows extended-length ``\\?\`` path
+    (ESPHome Desktop puts its bundled ccache on PATH that way). Such a path
+    runs fine through ``CreateProcess``, which is how ESP-IDF invokes it,
+    but SCons runs every compile through ``cmd.exe``, which fails on it with
+    "The system cannot find the path specified." (#18399), so the prefix is
+    stripped here with ``_strip_win_long_path_prefix()`` before the
+    runnability probe, which therefore validates the exact string the build
+    will execute.
+    ``ESPHOME_CCACHE_PATH`` is an internal channel, not a user setting: the
+    script only honours it together with ``ESPHOME_CCACHE_ENABLE=1``, and this
+    function always sets both or neither.
 
     The returned values are merged into the environment of the PlatformIO
     subprocess only, never into ``os.environ``: a long-running process
@@ -293,13 +308,27 @@ def _ccache_env() -> dict[str, str]:
     build dir. The other ``CCACHE_*`` values the user already set in the
     environment are respected.
     """
-    if "ESPHOME_CCACHE_ENABLE" in os.environ:
-        enabled = get_bool_env("ESPHOME_CCACHE_ENABLE")
-    else:
-        enabled = _ccache_usable()
-    env = {"ESPHOME_CCACHE_ENABLE": "1" if enabled else "0"}
-    if not enabled:
-        return env
+    explicit = "ESPHOME_CCACHE_ENABLE" in os.environ
+    if explicit and not get_bool_env("ESPHOME_CCACHE_ENABLE"):
+        return {"ESPHOME_CCACHE_ENABLE": "0"}
+    ccache_path = shutil.which("ccache")
+    if ccache_path is None:
+        if explicit:
+            _LOGGER.warning(
+                "ESPHOME_CCACHE_ENABLE is set but no ccache binary is on PATH; "
+                "compiling without ccache"
+            )
+        return {"ESPHOME_CCACHE_ENABLE": "0"}
+    # Strip before probing so the probe validates (and the failure warning
+    # names) the exact string the build will execute through cmd.exe.
+    ccache_path = _strip_win_long_path_prefix(ccache_path)
+    # An explicit opt-in skips the runnability probe.
+    if not explicit and not _ccache_runs(ccache_path):
+        return {"ESPHOME_CCACHE_ENABLE": "0"}
+    env = {
+        "ESPHOME_CCACHE_ENABLE": "1",
+        "ESPHOME_CCACHE_PATH": ccache_path,
+    }
     # build_path is set during preload for every config-loading command, so it
     # being unset means a caller built the environment too early; fail loudly
     # rather than with an opaque TypeError from Path(None).

esphome/vscode.py

@@ -3,12 +3,14 @@ from __future__ import annotations
 from io import StringIO
 import json
 from pathlib import Path
+import sys
+import traceback
 from typing import Any
 
 from esphome.config import Config, _format_vol_invalid, validate_config
 import esphome.config_validation as cv
 from esphome.const import __version__ as ESPHOME_VERSION
-from esphome.core import CORE, DocumentRange
+from esphome.core import CORE, DocumentRange, EsphomeError
 from esphome.yaml_util import parse_yaml
 
 
@@ -97,6 +99,16 @@ def _ace_loader(fname: Path) -> dict[str, Any]:
     return parse_yaml(fname, raw_yaml_stream)
 
 
+def _format_unexpected_error(err: Exception) -> str:
+    """Describe a crash inside validation with the frame it came from."""
+    message = f"Unexpected error while validating: {type(err).__name__}: {err}"
+    frames = traceback.extract_tb(err.__traceback__)
+    if not frames:
+        return message
+    frame = frames[-1]
+    return f"{message} ({frame.filename}:{frame.lineno} in {frame.name})"
+
+
 def _print_version():
     """Print ESPHome version."""
     print(
@@ -134,8 +146,12 @@ def read_config(args):
         try:
             config = loader(file_name)
             res = validate_config(config, command_line_substitutions)
-        except Exception as err:  # noqa: BLE001  # pylint: disable=broad-except
+        except (EsphomeError, cv.Invalid) as err:
             vs.add_yaml_error(str(err))
+        except Exception as err:  # noqa: BLE001  # pylint: disable=broad-except
+            # stdout carries the JSON protocol; the full chain goes to stderr.
+            traceback.print_exc(file=sys.stderr)
+            vs.add_yaml_error(_format_unexpected_error(err))
         else:
             for err in res.errors:
                 try:

platformio.ini

@@ -45,7 +45,7 @@ lib_deps_base =
 lib_deps =
     ${common.lib_deps_base}
     https://github.com/dudanov/MideaUART.git#eeea6c3e9b4474f067054592b435be1c4e466815 ; midea
-    esphome/noise-c@0.1.18                 ; api
+    esphome/noise-c@0.1.21                 ; api
     improv/Improv@1.2.6                    ; improv_serial / esp32_improv
     kikuchan98/pngle@1.1.0                 ; online_image
     ; Using the repository directly, otherwise ESP-IDF can't use the library
@@ -244,7 +244,7 @@ lib_deps =
     ${common:idf-component-libs.lib_deps}
     ESP32Async/ESPAsyncWebServer@3.9.6    ; web_server_base
     droscy/esp_wireguard@0.4.5            ; wireguard
-    esphome/noise-c@0.1.18                ; api
+    esphome/noise-c@0.1.21                ; api
     ESP32Async/AsyncTCP@3.4.5             ; async_tcp
     DNSServer                             ; captive_portal
     heman/AsyncMqttClient-esphome@2.0.0   ; mqtt
@@ -641,7 +641,7 @@ build_unflags =
 extends = common
 platform = platformio/native
 lib_deps =
-    esphome/noise-c@0.1.18  ; used by api
+    esphome/noise-c@0.1.21  ; used by api
     lvgl/lvgl@9.5.0         ; lvgl
 build_flags =
     ${common.build_flags}

pyproject.toml

@@ -1,5 +1,5 @@
 [build-system]
-requires = ["setuptools==84.0.0", "wheel>=0.43,<0.48"]
+requires = ["setuptools==84.0.0", "wheel>=0.43,<0.49"]
 build-backend = "setuptools.build_meta"
 
 [project]

requirements.txt

@@ -12,7 +12,7 @@ pyserial==3.5
 platformio==6.1.19
 esptool==5.3.1
 click==8.3.3
-aioesphomeapi==45.10.3
+aioesphomeapi==45.12.0
 aiohappyeyeballs==2.7.1  # Happy Eyeballs for requests downloads; already pulled in by aioesphomeapi
 zeroconf==0.150.0
 puremagic==2.2.0
@@ -20,14 +20,14 @@ ruamel.yaml==0.19.1 # dashboard_import
 ruamel.yaml.clib==0.2.15 # dashboard_import
 esphome-glyphsets==0.2.0
 pillow==12.3.0
-resvg-py==0.3.4
+resvg-py==0.4.0
 freetype-py==2.5.1
 jinja2==3.1.6
 bleak==3.0.2
 smpclient==7.2.0
 requests==2.34.2
 py7zr==1.1.3
-platformdirs==4.11.2  # native esp-idf toolchain global cache dir
+platformdirs==4.11.3  # native esp-idf toolchain global cache dir
 filelock==3.32.3  # inter-process locks (PlatformIO cache heal, git clone cache); >=3.32 for FileLock(fallback_to_soft=...), older versions silently drop the kwarg
 
 # esp-idf >= 5.0 requires this

script/build_language_schema.py

@@ -250,6 +250,16 @@ def add_pin_validators():
         "modes": ["input"],
     }
 
+    from esphome.components import gpio_expander
+
+    # Wraps pins.internal_gpio_input_pin_schema, so the editor schema must keep
+    # treating the config var as a pin
+    pin_validators[repr(gpio_expander.validate_interrupt_pin)] = {
+        "schema": True,
+        "internal": True,
+        "modes": ["input"],
+    }
+
 
 def add_module_registries(domain, module):
     for attr_name in dir(module):

script/helpers.py

@@ -558,8 +558,9 @@ def _get_changed_files_github_actions() -> list[str] | None:
             try:
                 return _get_changed_files_from_command(cmd)
             except Exception as e:
-                # If it fails due to the 300 file limit, use the API method
-                if "maximum" in str(e) and "files" in str(e):
+                # If it fails due to a diff limit (300 files or 20000 lines),
+                # use the API method which only returns filenames
+                if "diff exceeded the maximum" in str(e):
                     cmd = [
                         "gh",
                         "api",

tests/benchmarks/components/api/__init__.py

@@ -15,6 +15,7 @@ def override_manifest(manifest: ComponentManifestOverride) -> None:
         # components have hardware dependencies (BLE/UART/RMT); lightweight
         # stub headers in tests/benchmarks/stubs/ satisfy the includes.
         cg.add_define("USE_BLUETOOTH_PROXY")
+        cg.add_define("USE_BLUETOOTH_PROXY_CONNECTIONS")
         cg.add_define("BLUETOOTH_PROXY_MAX_CONNECTIONS", 3)
         cg.add_define("BLUETOOTH_PROXY_ADVERTISEMENT_BATCH_SIZE", 16)
         cg.add_define("USE_ZWAVE_PROXY")

tests/component_tests/gpio_expander/test_init.py

@@ -0,0 +1,61 @@
+"""Tests for the shared io expander interrupt_pin validator."""
+
+from __future__ import annotations
+
+import importlib
+
+import pytest
+
+from esphome import config_validation as cv
+from esphome.components.esp32 import KEY_BOARD, KEY_VARIANT, VARIANT_ESP32
+from esphome.components.gpio_expander import validate_interrupt_pin
+from esphome.const import PlatformFramework
+from tests.component_tests.types import SetCoreConfigCallable
+
+
+@pytest.fixture
+def stage_esp32(set_core_config: SetCoreConfigCallable) -> None:
+    set_core_config(
+        PlatformFramework.ESP32_IDF,
+        platform_data={KEY_BOARD: "esp32dev", KEY_VARIANT: VARIANT_ESP32},
+    )
+
+
+def test_plain_pin_accepted(stage_esp32: None) -> None:
+    value = validate_interrupt_pin(
+        {"number": 16, "mode": {"input": True, "pullup": True}}
+    )
+    assert value["number"] == 16
+
+
+def test_inverted_rejected(stage_esp32: None) -> None:
+    with pytest.raises(cv.Invalid, match="'inverted: true' is not supported"):
+        validate_interrupt_pin({"number": 16, "inverted": True})
+
+
+def test_allow_other_uses_rejected(stage_esp32: None) -> None:
+    with pytest.raises(cv.Invalid, match="'allow_other_uses: true' is not supported"):
+        validate_interrupt_pin({"number": 16, "allow_other_uses": True})
+
+
+# mcp23017 covers the shared mcp23xxx_base schema
+@pytest.mark.parametrize(
+    "component",
+    [
+        "pcf8574",
+        "pca9554",
+        "tca9555",
+        "pca6416a",
+        "pi4ioe5v6408",
+        "mcp23016",
+        "mcp23017",
+    ],
+)
+def test_component_schemas_route_through_validator(
+    stage_esp32: None, component: str
+) -> None:
+    module = importlib.import_module(f"esphome.components.{component}")
+    with pytest.raises(cv.Invalid, match="'inverted: true' is not supported"):
+        module.CONFIG_SCHEMA(
+            {"id": "expander_hub", "interrupt_pin": {"number": 16, "inverted": True}}
+        )

tests/component_tests/image/test_init.py

@@ -21,16 +21,20 @@ from esphome.components.image import (
     CONF_OPAQUE,
     CONF_TRANSPARENCY,
     PLATFORM_FILE,
+    _expand_platform_entry,
     _flatten_legacy_image_config,
     _is_legacy_image_format,
     _is_new_image_format,
     _migrate_legacy_image_config,
+    expand_platform_config,
     get_all_image_metadata,
     get_image_metadata,
 )
 from esphome.const import (
+    CONF_DEFAULTS,
     CONF_DITHER,
     CONF_FILE,
+    CONF_FILES,
     CONF_ID,
     CONF_PLATFORM,
     CONF_RAW_DATA_ID,
@@ -259,6 +263,15 @@ def test_flatten_keeps_byte_order_for_endian_type() -> None:
     assert out[0][CONF_BYTE_ORDER] == "little_endian"
 
 
+def test_flatten_drops_byte_order_written_directly_on_legacy_entry() -> None:
+    """The legacy flattener drops an incompatible byte_order even when written directly on the entry."""
+    out = _flatten_legacy_image_config(
+        {"binary": [{"id": "a", "file": "x.png", "byte_order": "little_endian"}]}
+    )
+    assert out == [{"id": "a", "file": "x.png", "type": "binary"}]
+    assert CONF_BYTE_ORDER not in out[0]
+
+
 def test_flatten_skips_meta_and_unknown_keys() -> None:
     out = _flatten_legacy_image_config(
         {
@@ -342,6 +355,42 @@ def test_migrate_legacy_warns_and_prepends_platform(
         ),
         pytest.param({"foo": 1}, False, id="dict_unknown_keys"),
         pytest.param("a string", False, id="scalar"),
+        # A `platform:`-tagged dict is the new format written without list brackets.
+        pytest.param(
+            {CONF_PLATFORM: "file", "id": "a", "file": "x.png"},
+            False,
+            id="platform_tagged_flat_dict",
+        ),
+        pytest.param(
+            {
+                CONF_PLATFORM: "file",
+                "defaults": {"type": "rgb565"},
+                "files": [{"id": "a", "file": "x.png"}],
+            },
+            False,
+            id="platform_tagged_defaults_files_dict",
+        ),
+        # `files:` without `platform:` is not legacy either -- the flattener has no branch for it.
+        pytest.param(
+            {
+                "defaults": {"type": "rgb565"},
+                "files": [{"id": "a", "file": "x.png"}],
+            },
+            False,
+            id="defaults_files_dict_without_platform",
+        ),
+        # Same as above in a list -- without this exclusion it would be silently
+        # migrated to a hard-coded `platform: file` instead of raising the error.
+        pytest.param(
+            [
+                {
+                    "defaults": {"type": "rgb565"},
+                    "files": [{"id": "a", "file": "x.png"}],
+                }
+            ],
+            False,
+            id="defaults_files_list_entry_without_platform",
+        ),
     ],
 )
 def test_is_legacy_image_format(config: object, expected: bool) -> None:
@@ -359,17 +408,290 @@ def test_is_legacy_image_format(config: object, expected: bool) -> None:
 def test_migrate_returns_none_for_invalid_legacy_shapes(
     config: object, caplog: pytest.LogCaptureFixture
 ) -> None:
-    """Unrecognised shapes are not migrated (and emit no warning) so normal
-    platform validation surfaces a proper error instead of silently dropping
-    the offending input."""
+    """Unrecognised shapes are not migrated (and emit no warning), so normal platform validation reports them."""
     with caplog.at_level(logging.WARNING):
         assert _migrate_legacy_image_config(config) is None
     assert "deprecated" not in caplog.text
 
 
+def test_migrate_returns_none_for_mapping_form_defaults_files() -> None:
+    """A `platform:`-tagged `defaults:`/`files:` mapping must not be swallowed by the legacy migrator."""
+    config = {
+        CONF_PLATFORM: "file",
+        "defaults": {"type": "rgb565"},
+        "files": [{"id": "a", "file": "a.png"}],
+    }
+    assert _migrate_legacy_image_config(config) is None
+
+
+def test_migrate_returns_none_for_defaults_files_dict_without_platform() -> None:
+    """`defaults:`/`files:` without `platform:` must not be swallowed either -- the flattener has
+    no `files:` branch and would silently return `[]`."""
+    config = {
+        "defaults": {"type": "rgb565"},
+        "files": [{"id": "a", "file": "a.png"}],
+    }
+    assert _migrate_legacy_image_config(config) is None
+
+
+def test_migrate_returns_none_for_defaults_files_list_entry_without_platform() -> None:
+    """Same, in a list -- previously the list branch migrated it to a hard-coded
+    `platform: file` instead of raising a missing-platform error."""
+    config = [
+        {
+            "defaults": {"type": "rgb565"},
+            "files": [{"id": "a", "file": "a.png"}],
+        }
+    ]
+    assert _migrate_legacy_image_config(config) is None
+
+
 # --------------------------- end legacy migration --------------------------
 
 
+def test_expand_platform_entry_passes_through_plain_entry() -> None:
+    entry = {CONF_PLATFORM: "file", "id": "a", "file": "x.png"}
+    assert _expand_platform_entry(0, entry) == [entry]
+
+
+def test_expand_platform_entry_expands_files_with_defaults() -> None:
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_DEFAULTS: {"type": "RGB565", "transparency": "opaque"},
+        CONF_FILES: [
+            {"id": "img1", "file": "foo.png"},
+            {"id": "img2", "file": "bar.png", "type": "GRAYSCALE"},
+        ],
+    }
+    assert _expand_platform_entry(0, entry) == [
+        {
+            CONF_PLATFORM: "file",
+            "id": "img1",
+            "file": "foo.png",
+            "type": "RGB565",
+            "transparency": "opaque",
+        },
+        {
+            CONF_PLATFORM: "file",
+            "id": "img2",
+            "file": "bar.png",
+            "type": "GRAYSCALE",
+            "transparency": "opaque",
+        },
+    ]
+
+
+def test_expand_platform_entry_files_without_defaults() -> None:
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_FILES: [{"id": "img1", "file": "foo.png"}],
+    }
+    assert _expand_platform_entry(0, entry) == [
+        {CONF_PLATFORM: "file", "id": "img1", "file": "foo.png"}
+    ]
+
+
+def test_expand_platform_entry_preserves_source_range() -> None:
+    """A merged entry keeps the source range of its `files:` item so whole-entry errors anchor there."""
+    from esphome import yaml_util
+
+    file_entry = yaml_util.make_data_base({"id": "img1", "file": "foo.png"})
+    file_entry._esp_range = "sentinel-range"
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_DEFAULTS: {"type": "RGB565"},
+        CONF_FILES: [file_entry],
+    }
+    [out] = _expand_platform_entry(0, entry)
+    assert isinstance(out, yaml_util.ESPHomeDataBase)
+    assert out.esp_range == "sentinel-range"
+
+
+def test_expand_platform_entry_plain_dict_file_entry_has_no_source_range() -> None:
+    """Plain-dict `files:` items must not crash -- `from_database` reads `.esp_range` unconditionally."""
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_FILES: [{"id": "img1", "file": "foo.png"}],
+    }
+    [out] = _expand_platform_entry(0, entry)
+    assert out == {CONF_PLATFORM: "file", "id": "img1", "file": "foo.png"}
+
+
+def test_expand_platform_entry_per_file_overrides_win() -> None:
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_DEFAULTS: {"type": "RGB565"},
+        CONF_FILES: [{"id": "img1", "file": "foo.png", "type": "BINARY"}],
+    }
+    [out] = _expand_platform_entry(0, entry)
+    assert out["type"] == "BINARY"
+
+
+def test_expand_platform_entry_drops_byte_order_for_non_endian_override() -> None:
+    """A `byte_order` default merged into a non-endian override is dropped, as the legacy flattener did."""
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_DEFAULTS: {"type": "rgb565", "byte_order": "little_endian"},
+        CONF_FILES: [
+            {"id": "a", "file": "x.png"},
+            {"id": "b", "file": "y.png", "type": "binary"},
+        ],
+    }
+    out = _expand_platform_entry(0, entry)
+    assert out[0]["byte_order"] == "little_endian"
+    assert "byte_order" not in out[1]
+
+
+def test_expand_platform_entry_invalid_byte_order_in_defaults_raises() -> None:
+    """A dropped `byte_order` inherited from `defaults:` is still validated, so a typo raises."""
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_DEFAULTS: {"type": "rgb565", "byte_order": "little_andian"},
+        CONF_FILES: [{"id": "a", "file": "x.png", "type": "binary"}],
+    }
+    with pytest.raises(cv.Invalid, match="did you mean") as excinfo:
+        _expand_platform_entry(0, entry)
+    assert excinfo.value.path == [0]
+
+
+def test_expand_platform_entry_keeps_byte_order_for_endian_override() -> None:
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_DEFAULTS: {"type": "rgb565", "byte_order": "big_endian"},
+        CONF_FILES: [{"id": "a", "file": "x.png", "type": "rgb565"}],
+    }
+    [out] = _expand_platform_entry(0, entry)
+    assert out["byte_order"] == "big_endian"
+
+
+def test_expand_platform_entry_keeps_explicit_byte_order_conflict() -> None:
+    """A `byte_order` written directly on the entry is kept so validate_settings raises the normal error."""
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_DEFAULTS: {"type": "rgb565"},
+        CONF_FILES: [
+            {
+                "id": "a",
+                "file": "x.png",
+                "type": "binary",
+                "byte_order": "little_endian",
+            }
+        ],
+    }
+    [out] = _expand_platform_entry(0, entry)
+    assert out["byte_order"] == "little_endian"
+
+
+def test_expand_platform_entry_defaults_without_files_raises() -> None:
+    entry = {CONF_PLATFORM: "file", CONF_DEFAULTS: {"type": "RGB565"}}
+    with pytest.raises(cv.Invalid, match="may only be used together with") as excinfo:
+        _expand_platform_entry(0, entry)
+    assert excinfo.value.path == [0]
+
+
+def test_expand_platform_entry_null_files_raises_not_empty() -> None:
+    """A `files:` key with no value parses to `None` and must be reported clearly."""
+    entry = {CONF_PLATFORM: "file", CONF_DEFAULTS: {"type": "RGB565"}, CONF_FILES: None}
+    with pytest.raises(cv.Invalid, match="must not be empty"):
+        _expand_platform_entry(0, entry)
+
+
+def test_expand_platform_entry_empty_files_list_raises_not_empty() -> None:
+    """An explicit `files: []` must not silently drop the whole platform entry."""
+    entry = {CONF_PLATFORM: "file", CONF_FILES: []}
+    with pytest.raises(cv.Invalid, match="must not be empty"):
+        _expand_platform_entry(0, entry)
+
+
+def test_expand_platform_entry_files_with_stray_key_raises() -> None:
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_FILES: [{"id": "a", "file": "x.png"}],
+        "extra": 1,
+    }
+    with pytest.raises(cv.Invalid, match="cannot be combined with"):
+        _expand_platform_entry(0, entry)
+
+
+def test_expand_platform_entry_id_in_defaults_raises() -> None:
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_DEFAULTS: {CONF_ID: "a"},
+        CONF_FILES: [{"file": "x.png"}],
+    }
+    with pytest.raises(cv.Invalid, match="not allowed inside"):
+        _expand_platform_entry(0, entry)
+
+
+def test_expand_platform_entry_platform_in_defaults_raises() -> None:
+    """`platform:` inside `defaults:` would silently reassign every file's platform."""
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_DEFAULTS: {CONF_PLATFORM: "animation"},
+        CONF_FILES: [{"id": "a", "file": "x.png"}],
+    }
+    with pytest.raises(cv.Invalid, match="not allowed inside"):
+        _expand_platform_entry(0, entry)
+
+
+def test_expand_platform_entry_platform_in_file_entry_raises() -> None:
+    """`platform:` on a `files:` item must not silently override the entry's platform."""
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_FILES: [{"id": "a", "file": "x.png", CONF_PLATFORM: "animation"}],
+    }
+    with pytest.raises(cv.Invalid, match="not allowed inside"):
+        _expand_platform_entry(0, entry)
+
+
+def test_expand_platform_entry_files_not_list_raises() -> None:
+    entry = {CONF_PLATFORM: "file", CONF_FILES: "not-a-list"}
+    with pytest.raises(cv.Invalid, match="must be a list"):
+        _expand_platform_entry(0, entry)
+
+
+def test_expand_platform_entry_defaults_not_mapping_raises() -> None:
+    entry = {
+        CONF_PLATFORM: "file",
+        CONF_DEFAULTS: "not-a-mapping",
+        CONF_FILES: [{"id": "a", "file": "x.png"}],
+    }
+    with pytest.raises(cv.Invalid, match="must be a mapping"):
+        _expand_platform_entry(0, entry)
+
+
+def test_expand_platform_entry_file_item_not_mapping_raises() -> None:
+    entry = {CONF_PLATFORM: "file", CONF_FILES: [1, 2]}
+    with pytest.raises(cv.Invalid, match="must be a mapping"):
+        _expand_platform_entry(0, entry)
+
+
+def test_expand_platform_config_mixes_plain_and_expanded_entries() -> None:
+    config = [
+        {
+            CONF_PLATFORM: "file",
+            CONF_DEFAULTS: {"type": "RGB565"},
+            CONF_FILES: [
+                {"id": "img1", "file": "foo.png"},
+                {"id": "img2", "file": "bar.png"},
+            ],
+        },
+        {CONF_PLATFORM: "file", "id": "plain", "file": "baz.png", "type": "BINARY"},
+    ]
+    out = expand_platform_config(config)
+    assert [entry["id"] for entry in out] == ["img1", "img2", "plain"]
+
+
+def test_expand_platform_config_ignores_non_platform_entries() -> None:
+    # Not expanded here -- legacy_config_migrate runs before this hook and is
+    # responsible for tagging/flattening pre-platform shapes.
+    config = ["not-a-platform-entry"]
+    assert expand_platform_config(config) == config
+
+
+# --------------------- end defaults/files expansion -------------------------
+
+
 def test_validate_image_final_defaults_to_little_endian() -> None:
     config = {CONF_FILE: "x.png"}
     validate_image_final(config)

tests/components/addressable_light/common-ard-esp32_rmt_led_strip.yaml

@@ -3,7 +3,7 @@ light:
     id: led_matrix_32x8
     default_transition_length: 500ms
     chipset: ws2812
-    rgb_order: GRB
+    channel_colors: GRB
     num_leds: 256
     pin: ${pin}
 

tests/components/addressable_light/common-idf-esp32_rmt_led_strip.yaml

@@ -3,7 +3,7 @@ light:
     id: led_matrix_32x8
     default_transition_length: 500ms
     chipset: ws2812
-    rgb_order: GRB
+    channel_colors: GRB
     num_leds: 256
     pin: ${pin}
 

tests/components/animation/validate-platform-defaults.host.yaml

@@ -0,0 +1,21 @@
+# `platform: animation` entry exercising the shared `defaults:`/`files:` expansion.
+display:
+  - platform: sdl
+    id: animation_display
+    auto_clear_enabled: false
+    dimensions:
+      width: 480
+      height: 480
+
+image:
+  - platform: animation
+    defaults:
+      type: rgb565
+      transparency: opaque
+      resize: 50x50
+    files:
+      - id: platform_defaults_animation
+        file: $component_dir/anim.gif
+      - id: platform_defaults_animation_rgb
+        file: $component_dir/anim.apng
+        type: rgb

tests/components/beken_spi_led_strip/test.bk72xx-ard.yaml

@@ -1,6 +1,6 @@
 light:
   - platform: beken_spi_led_strip
-    rgb_order: GRB
+    channel_colors: GRB
     pin: P16
     num_leds: 30
     chipset: ws2812

tests/components/beken_spi_led_strip/validate-legacy.bk72xx-ard.yaml

@@ -0,0 +1,10 @@
+# The deprecated rgb_order / is_rgbw / is_wrgb keys, kept working until 2027.3.0.
+# Config-only, and only one strip because P16 is the sole supported pin.
+light:
+  - platform: beken_spi_led_strip
+    name: Legacy RGBW
+    pin: P16
+    num_leds: 30
+    chipset: sk6812
+    rgb_order: GRB
+    is_rgbw: true # -> GRBW

tests/components/e131/common-ard.yaml

@@ -5,7 +5,7 @@ light:
     id: led_matrix_32x8
     default_transition_length: 500ms
     chipset: ws2812
-    rgb_order: GRB
+    channel_colors: GRB
     num_leds: 256
     pin: ${pin}
     effects:

tests/components/e131/common-idf.yaml

@@ -5,7 +5,7 @@ light:
     id: led_matrix_32x8
     default_transition_length: 500ms
     chipset: ws2812
-    rgb_order: GRB
+    channel_colors: GRB
     num_leds: 256
     pin: ${pin}
     effects:

tests/components/e131/test.rp2040-ard.yaml

@@ -6,7 +6,7 @@ light:
     pin: 2
     pio: 0
     num_leds: 256
-    rgb_order: GRB
+    channel_colors: GRB
     chipset: WS2812
     effects:
       - e131:

tests/components/esp32_rmt_led_strip/common.yaml

@@ -3,13 +3,13 @@ light:
     id: led_strip1
     pin: ${pin1}
     num_leds: 60
-    rgb_order: GRB
+    channel_colors: GRB
     chipset: ws2812
   - platform: esp32_rmt_led_strip
     id: led_strip2
     pin: ${pin2}
     num_leds: 60
-    rgbw_order: RWGB
+    channel_colors: RWGB
     bit0_high: 100us
     bit0_low: 100us
     bit1_high: 100us

tests/components/esp32_rmt_led_strip/test.esp32-s3-idf.yaml

@@ -8,14 +8,14 @@ light:
     id: led_strip1
     pin: ${pin1}
     num_leds: 60
-    rgb_order: GRB
+    channel_colors: GRB
     chipset: ws2812
     use_dma: "true"
   - platform: esp32_rmt_led_strip
     id: led_strip2
     pin: ${pin2}
     num_leds: 60
-    rgb_order: RGB
+    channel_colors: RGB
     bit0_high: 100us
     bit0_low: 100us
     bit1_high: 100us

tests/components/esp32_rmt_led_strip/validate-legacy.esp32-idf.yaml

@@ -0,0 +1,23 @@
+# The deprecated rgb_order / is_rgbw / is_wrgb keys, kept working until 2027.3.0.
+# Config-only: each strip below must migrate to the channel_colors shown in the comment.
+light:
+  - platform: esp32_rmt_led_strip
+    id: legacy_rgb
+    pin: GPIO13
+    num_leds: 60
+    chipset: ws2812
+    rgb_order: GRB # -> GRB
+  - platform: esp32_rmt_led_strip
+    id: legacy_rgbw
+    pin: GPIO14
+    num_leds: 60
+    chipset: sk6812
+    rgb_order: GRB
+    is_rgbw: true # -> GRBW
+  - platform: esp32_rmt_led_strip
+    id: legacy_wrgb
+    pin: GPIO15
+    num_leds: 60
+    chipset: sk6812
+    rgb_order: GRB
+    is_wrgb: true # -> WGRB

tests/components/image/validate-platform-defaults.host.yaml

@@ -0,0 +1,24 @@
+# `platform: file` entry using the `defaults:`/`files:` shape, including the
+# per-type byte_order drop when an entry overrides to a non-endian type.
+display:
+  - platform: sdl
+    id: image_display
+    auto_clear_enabled: false
+    dimensions:
+      width: 480
+      height: 480
+
+image:
+  - platform: file
+    defaults:
+      type: rgb565
+      transparency: opaque
+      byte_order: little_endian
+      resize: 50x50
+      dither: FloydSteinberg
+    files:
+      - id: platform_defaults_image
+        file: ../../pnglogo.png
+      - id: platform_defaults_binary
+        file: ../../pnglogo.png
+        type: binary

tests/components/modbus/common.h

@@ -1,7 +1,10 @@
 #pragma once
 #include <cstdint>
+#include <cstring>
+#include <span>
 #include <vector>
 #include "esphome/components/uart/uart_component.h"
+#include "esphome/core/helpers.h"
 
 namespace esphome::modbus::testing {
 
@@ -30,4 +33,37 @@ class RecordingUART : public NullUART {
   std::vector<uint8_t> written;
 };
 
+// A UART the test can inject received bytes into, so frames travel the full receive path
+// (receive_modbus_frames -> parse -> dispatch) through hub.loop(). Writes are recorded.
+class InjectableUART : public RecordingUART {
+ public:
+  bool peek_byte(uint8_t *data) override {
+    if (this->rx_.empty())
+      return false;
+    *data = this->rx_.front();
+    return true;
+  }
+  bool read_array(uint8_t *data, size_t len) override {
+    if (len > this->rx_.size())
+      return false;
+    memcpy(data, this->rx_.data(), len);
+    this->rx_.erase(this->rx_.begin(), this->rx_.begin() + len);
+    return true;
+  }
+  size_t available() override { return this->rx_.size(); }
+
+  // Queues a complete wire frame: address + PDU + CRC16 (low byte first).
+  void inject_frame(uint8_t address, std::span<const uint8_t> pdu) {
+    size_t start = this->rx_.size();
+    this->rx_.push_back(address);
+    this->rx_.insert(this->rx_.end(), pdu.begin(), pdu.end());
+    uint16_t crc = crc16(this->rx_.data() + start, this->rx_.size() - start);
+    this->rx_.push_back(crc & 0xFF);
+    this->rx_.push_back(crc >> 8);
+  }
+
+ private:
+  std::vector<uint8_t> rx_;
+};
+
 }  // namespace esphome::modbus::testing

tests/components/modbus/modbus_unknown_function_test.cpp

@@ -0,0 +1,141 @@
+#include <gtest/gtest.h>
+
+#include <cstdint>
+#include <span>
+#include <vector>
+
+#include "common.h"
+#include "esphome/components/modbus/modbus.h"
+
+namespace esphome::modbus::testing {
+
+namespace {
+
+// Records custom-response dispatches so tests can assert an unknown-length frame reached the device.
+class CustomRecordingDevice : public ModbusClientDevice {
+ public:
+  using ModbusClientDevice::ModbusClientDevice;
+  void on_custom_response(std::span<const uint8_t> request_pdu, std::span<const uint8_t> response_pdu,
+                          ResponseStatus status) override {
+    this->requests.emplace_back(request_pdu.begin(), request_pdu.end());
+    this->responses.emplace_back(response_pdu.begin(), response_pdu.end());
+    this->statuses.push_back(status);
+  }
+  std::vector<std::vector<uint8_t>> requests;
+  std::vector<std::vector<uint8_t>> responses;
+  std::vector<ResponseStatus> statuses;
+};
+
+// Every handler keeps its ILLEGAL_FUNCTION default; the hub's dispatch is what is under test.
+class SilentServerDevice : public ModbusServerDevice {};
+
+// Drives full client frames through the server hub's receive path (same shape as the broadcast tests).
+class TestServerHub : public ModbusServerHub {
+ public:
+  bool tx_blocked() override { return false; }
+
+  // Builds a complete client frame (address + FC + data + CRC) and runs the full receive-side parser.
+  // Returns true once the buffer has fully drained.
+  bool run_receive_parser_for_test(uint8_t address, uint8_t function_code, std::span<const uint8_t> data) {
+    this->rx_buffer_.clear();
+    this->rx_buffer_.reserve(data.size() + 4);
+    this->rx_buffer_.push_back(address);
+    this->rx_buffer_.push_back(function_code);
+    this->rx_buffer_.insert(this->rx_buffer_.end(), data.begin(), data.end());
+    uint16_t crc = crc16(this->rx_buffer_.data(), this->rx_buffer_.size());
+    this->rx_buffer_.push_back(crc & 0xFF);
+    this->rx_buffer_.push_back(crc >> 8);
+    this->parse_modbus_frames();
+    return this->rx_buffer_.empty();
+  }
+};
+
+}  // namespace
+
+// The frame-length parsers have explicit cases for exactly these 13 codes; every other value - the
+// assigned-but-unimplemented management codes, both user-defined ranges, and all unassigned codes -
+// must classify as unknown length. The exception flag masks off first.
+TEST(ModbusUnknownFunction, HelperMatchesParserCoverage) {
+  for (uint8_t fc : {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x0F, 0x10, 0x14, 0x15, 0x16, 0x17, 0x18}) {
+    EXPECT_FALSE(helpers::is_function_code_unknown_length(fc)) << "fc 0x" << std::hex << int(fc);
+  }
+  for (uint8_t fc : {0x07, 0x08, 0x0B, 0x0C, 0x11, 0x2A, 0x41, 0x48, 0x49, 0x64, 0x6E, 0x00, 0x7F}) {
+    EXPECT_TRUE(helpers::is_function_code_unknown_length(fc)) << "fc 0x" << std::hex << int(fc);
+  }
+  // Exception replies classify by their base code.
+  EXPECT_FALSE(helpers::is_function_code_unknown_length(0x83));
+  EXPECT_TRUE(helpers::is_function_code_unknown_length(0x87));
+  // Strictly wider than the user-defined ranges: every custom code is unknown-length, but not vice versa.
+  for (int fc = 0; fc <= 0xFF; fc++) {
+    if (helpers::is_function_code_custom(fc))
+      EXPECT_TRUE(helpers::is_function_code_unknown_length(fc)) << "fc 0x" << std::hex << fc;
+  }
+  EXPECT_FALSE(helpers::is_function_code_custom(0x49));
+
+  // Derived contract check: the helper must say "unknown" exactly when both length parsers fall
+  // through to default. With a zero-filled max-size PDU every explicit case returns at least 2
+  // (file records bottom out at 2, FIFO at 3) and only default returns MIN_PDU_SIZE, so comparing
+  // against MIN_PDU_SIZE detects a case added to either switch without updating the helper. The
+  // loop stops at 0x7F: above it the helper masks the exception flag off while client_pdu_length()
+  // switches on the unmasked byte and server_pdu_length() early-returns the exception length.
+  for (int fc = 0; fc <= 0x7F; fc++) {
+    const uint8_t pdu[MAX_PDU_SIZE] = {static_cast<uint8_t>(fc)};  // zero header fields
+    EXPECT_EQ(helpers::is_function_code_unknown_length(fc),
+              helpers::client_pdu_length(pdu, sizeof(pdu)) == MIN_PDU_SIZE)
+        << "client_pdu_length disagrees for fc 0x" << std::hex << fc;
+    EXPECT_EQ(helpers::is_function_code_unknown_length(fc),
+              helpers::server_pdu_length(pdu, sizeof(pdu)) == MIN_PDU_SIZE)
+        << "server_pdu_length disagrees for fc 0x" << std::hex << fc;
+  }
+}
+
+// A response with a function code outside the user-defined ranges (0x49) has no length case in
+// server_pdu_length(), so the parser must find the frame end by CRC scan - the same way it already
+// handles user-defined codes. Frame: address + FC 0x49 + 3 data bytes + CRC = 7 bytes. Without the
+// scan the parser assumes a 4-byte frame, fails the CRC, and the response never reaches the device.
+TEST(ModbusUnknownFunction, ClientParsesUnknownLengthResponse) {
+  InjectableUART uart;
+  ModbusClientHub hub;
+  hub.set_uart_parent(&uart);
+  hub.setup();  // computes frame timing from the baud rate
+  CustomRecordingDevice device(&hub, 0x02);
+
+  const uint8_t request[] = {0x49, 0x01};
+  ASSERT_TRUE(device.queue_pdu(request));
+  hub.loop();  // transmit
+  ASSERT_FALSE(uart.written.empty());
+
+  const uint8_t response_pdu[] = {0x49, 0x02, 0xAA, 0xBB};
+  uart.inject_frame(0x02, response_pdu);
+  hub.loop();  // receive + parse + match + dispatch
+
+  ASSERT_EQ(device.responses.size(), 1u);
+  EXPECT_EQ(device.requests[0], std::vector<uint8_t>(request, request + sizeof(request)));
+  EXPECT_EQ(device.responses[0], std::vector<uint8_t>(response_pdu, response_pdu + sizeof(response_pdu)));
+  EXPECT_FALSE(device.statuses[0].has_value());
+}
+
+// The server side of the same gap: a request with FC 0x49 for a registered device must parse (CRC
+// scan again) so the hub can answer ILLEGAL_FUNCTION per the spec. Without the scan the frame fails
+// to parse and the client gets silence instead of the exception.
+TEST(ModbusUnknownFunction, ServerRepliesIllegalFunctionToUnknownLengthRequest) {
+  TestServerHub hub;
+  RecordingUART uart;
+  hub.set_uart_parent(&uart);
+
+  SilentServerDevice device;
+  device.set_address(0x02);
+  hub.register_device(&device);
+
+  const uint8_t data[] = {0x02, 0xAA, 0xBB};
+  ASSERT_TRUE(hub.run_receive_parser_for_test(0x02, 0x49, data));
+
+  // Expected reply: address + FC with exception flag + ILLEGAL_FUNCTION + CRC.
+  std::vector<uint8_t> expected = {0x02, 0xC9, 0x01};
+  uint16_t crc = crc16(expected.data(), expected.size());
+  expected.push_back(crc & 0xFF);
+  expected.push_back(crc >> 8);
+  EXPECT_EQ(uart.written, expected);
+}
+
+}  // namespace esphome::modbus::testing

tests/components/partition/common-ard.yaml

@@ -4,7 +4,7 @@ light:
     default_transition_length: 500ms
     chipset: ws2812
     num_leds: 256
-    rgb_order: GRB
+    channel_colors: GRB
     pin: ${pin}
   - platform: partition
     name: Partition Light

tests/components/partition/common-idf.yaml

@@ -4,7 +4,7 @@ light:
     default_transition_length: 500ms
     chipset: ws2812
     num_leds: 256
-    rgb_order: GRB
+    channel_colors: GRB
     pin: ${pin}
   - platform: partition
     name: Partition Light

tests/components/rp2040_pio_led_strip/common.yaml

@@ -4,14 +4,14 @@ light:
     pin: 4
     num_leds: 60
     pio: 0
-    rgb_order: GRB
+    channel_colors: GRB
     chipset: WS2812
   - platform: rp2040_pio_led_strip
     id: led_strip_custom_timings
     pin: 5
     num_leds: 60
     pio: 1
-    rgb_order: GRB
+    channel_colors: GRB
     bit0_high: .1us
     bit0_low: 1.2us
     bit1_high: .69us

tests/components/rp2040_pio_led_strip/validate-legacy.rp2040-ard.yaml

@@ -0,0 +1,18 @@
+# The deprecated rgb_order / is_rgbw keys, kept working until 2027.3.0.
+# Config-only: each strip below must migrate to the channel_colors shown in the comment.
+light:
+  - platform: rp2040_pio_led_strip
+    id: legacy_rgb
+    pin: 4
+    num_leds: 60
+    pio: 0
+    chipset: WS2812
+    rgb_order: GRB # -> GRB
+  - platform: rp2040_pio_led_strip
+    id: legacy_rgbw
+    pin: 5
+    num_leds: 60
+    pio: 1
+    chipset: SK6812
+    rgb_order: GRB
+    is_rgbw: true # -> GRBW

tests/components/web_server/common-ap-fallback.yaml

@@ -0,0 +1,11 @@
+# STA with AP fallback plus local: true opts the fallback into captive AP mode; exercises
+# the runtime start (fallback branch in wifi loop) and end (on STA connect) paths.
+wifi:
+  ssid: MySSID
+  password: password1
+  ap:
+    ssid: "ESPHome-Test"
+    password: "Test1234!"
+
+web_server:
+  local: true

tests/components/web_server/common-ap-mode.yaml

@@ -0,0 +1,9 @@
+# AP mode: with a WiFi access point and the interface embedded in the firmware, web_server
+# runs its own captive portal (DNS server, unknown URLs redirect to the page).
+wifi:
+  ap:
+    ssid: "ESPHome-Test"
+    password: "Test1234!"
+
+web_server:
+  local: true

tests/components/web_server/test-ap-fallback.esp32-idf.yaml

@@ -0,0 +1,2 @@
+packages:
+  web_server: !include common-ap-fallback.yaml

tests/components/web_server/test-ap-mode.esp32-idf.yaml

@@ -0,0 +1,2 @@
+packages:
+  web_server: !include common-ap-mode.yaml

tests/components/web_server/test-ap-mode.esp8266-ard.yaml

@@ -0,0 +1,2 @@
+packages:
+  web_server: !include common-ap-mode.yaml

tests/components/wled/test.esp32-ard.yaml

@@ -9,7 +9,7 @@ light:
     id: led_matrix_32x8
     default_transition_length: 500ms
     chipset: ws2812
-    rgb_order: GRB
+    channel_colors: GRB
     num_leds: 256
     pin: 2
     effects:

tests/script/test_helpers.py

@@ -244,6 +244,44 @@ def test_get_changed_files_github_actions_pull_request_large_pr(
         assert result == expected_files
 
 
+def test_get_changed_files_github_actions_pull_request_large_diff(
+    monkeypatch: MonkeyPatch,
+) -> None:
+    """Test _get_changed_files_github_actions fallback for PRs with >20000 diff lines."""
+    monkeypatch.setenv("GITHUB_EVENT_NAME", "pull_request")
+
+    expected_files = ["file1.py", "file2.cpp"]
+
+    with (
+        patch("helpers._get_pr_number_from_github_env", return_value="17909"),
+        patch("helpers._get_changed_files_from_command") as mock_get,
+    ):
+        # First call fails with too many diff lines error, second succeeds with API method
+        mock_get.side_effect = [
+            Exception(
+                "could not find pull request diff: HTTP 406: Sorry, "
+                "the diff exceeded the maximum number of lines (20000)"
+            ),
+            expected_files,
+        ]
+
+        result = _get_changed_files_github_actions()
+
+        assert mock_get.call_count == 2
+        mock_get.assert_any_call(["gh", "pr", "diff", "17909", "--name-only"])
+        mock_get.assert_any_call(
+            [
+                "gh",
+                "api",
+                "repos/esphome/esphome/pulls/17909/files",
+                "--paginate",
+                "--jq",
+                ".[].filename",
+            ]
+        )
+        assert result == expected_files
+
+
 def test_get_changed_files_github_actions_pull_request_other_error(
     monkeypatch: MonkeyPatch,
 ) -> None:

tests/unit_tests/components/light/test_channel_colors.py

@@ -0,0 +1,144 @@
+"""Tests for the shared addressable-strip channel order helpers."""
+
+import logging
+
+import pytest
+
+from esphome.components.const import CONF_CHANNEL_COLORS, CONF_IS_WRGB
+from esphome.components.light import (
+    channel_colors_struct,
+    migrate_channel_colors,
+    validate_channel_colors,
+)
+import esphome.config_validation as cv
+from esphome.const import CONF_IS_RGBW, CONF_RGB_ORDER
+from esphome.types import ConfigType
+
+NO_WHITE = "light::ChannelColors::NO_WHITE"
+
+
+@pytest.mark.parametrize(
+    ("value", "expected"),
+    [
+        ("RGB", "RGB"),
+        ("grb", "GRB"),
+        ("BRG", "BRG"),
+        ("rgbw", "RGBW"),
+        ("WRGB", "WRGB"),
+        ("GWRB", "GWRB"),
+    ],
+)
+def test_validate_channel_colors(value: str, expected: str) -> None:
+    assert validate_channel_colors(value) == expected
+
+
+@pytest.mark.parametrize(
+    "value",
+    [
+        "RG",  # missing a channel
+        "RGBB",  # duplicate channel
+        "RRGB",  # duplicate channel, correct length
+        "RGBWW",  # two white channels
+        "RGBX",  # unknown channel
+        "RGBWX",  # unknown channel, correct length
+        "",
+    ],
+)
+def test_validate_channel_colors_rejects_invalid(value: str) -> None:
+    with pytest.raises(cv.Invalid, match="is not a valid channel order"):
+        validate_channel_colors(value)
+
+
+@pytest.mark.parametrize(
+    ("value", "expected"),
+    [
+        ("RGB", (0, 1, 2, NO_WHITE)),
+        ("GRB", (1, 0, 2, NO_WHITE)),
+        ("BRG", (1, 2, 0, NO_WHITE)),
+        ("RGBW", (0, 1, 2, 3)),
+        ("GRBW", (1, 0, 2, 3)),
+        ("WRGB", (1, 2, 3, 0)),
+        ("GWRB", (2, 0, 3, 1)),
+    ],
+)
+def test_channel_colors_struct(value: str, expected: tuple[int, int, int, int]) -> None:
+    struct = channel_colors_struct(value)
+    assert str(struct.base) == "light::ChannelColors"
+    assert tuple(str(arg) for arg in struct.args.values()) == tuple(
+        str(field) for field in expected
+    )
+
+
+def _migrate(config: ConfigType) -> ConfigType:
+    return migrate_channel_colors(removed_in="2027.3.0", component="test_strip")(config)
+
+
+def test_migrate_passes_through_channel_colors() -> None:
+    config = {CONF_CHANNEL_COLORS: "GRBW"}
+    assert _migrate(config) == {CONF_CHANNEL_COLORS: "GRBW"}
+
+
+@pytest.mark.parametrize(
+    ("deprecated", "expected", "named"),
+    [
+        ({}, "GRB", "'rgb_order' is"),
+        (
+            {CONF_IS_RGBW: False, CONF_IS_WRGB: False},
+            "GRB",
+            "'rgb_order', 'is_rgbw' and 'is_wrgb' are",
+        ),
+        ({CONF_IS_RGBW: True}, "GRBW", "'rgb_order' and 'is_rgbw' are"),
+        ({CONF_IS_WRGB: True}, "WGRB", "'rgb_order' and 'is_wrgb' are"),
+    ],
+)
+def test_migrate_folds_deprecated_keys(
+    deprecated: ConfigType,
+    expected: str,
+    named: str,
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    config = {CONF_RGB_ORDER: "GRB", "num_leds": 1, **deprecated}
+    with caplog.at_level(logging.WARNING):
+        result = _migrate(config)
+
+    assert result == {CONF_CHANNEL_COLORS: expected, "num_leds": 1}
+    assert f"[test_strip] {named} deprecated" in caplog.text
+    assert f"'{CONF_CHANNEL_COLORS}: {expected}'" in caplog.text
+    assert "2027.3.0" in caplog.text
+
+
+def test_migrate_does_not_mutate_input() -> None:
+    config = {CONF_RGB_ORDER: "GRB", CONF_IS_RGBW: True}
+    _migrate(config)
+    assert config == {CONF_RGB_ORDER: "GRB", CONF_IS_RGBW: True}
+
+
+@pytest.mark.parametrize("deprecated", [CONF_RGB_ORDER, CONF_IS_RGBW, CONF_IS_WRGB])
+def test_migrate_rejects_mixing_old_and_new(deprecated: str) -> None:
+    config = {CONF_CHANNEL_COLORS: "GRBW", deprecated: "GRB"}
+    with pytest.raises(cv.Invalid, match=f"cannot be combined with '{deprecated}'"):
+        _migrate(config)
+
+
+def test_migrate_reports_every_conflicting_key() -> None:
+    config = {
+        CONF_CHANNEL_COLORS: "GRBW",
+        CONF_RGB_ORDER: "GRB",
+        CONF_IS_RGBW: True,
+        CONF_IS_WRGB: False,
+    }
+    with pytest.raises(
+        cv.Invalid, match="cannot be combined with 'rgb_order', 'is_rgbw' and 'is_wrgb'"
+    ):
+        _migrate(config)
+
+
+def test_migrate_requires_channel_colors() -> None:
+    with pytest.raises(cv.Invalid, match=f"'{CONF_CHANNEL_COLORS}' is required"):
+        _migrate({"num_leds": 1})
+
+
+def test_migrate_rejects_is_rgbw_with_is_wrgb() -> None:
+    config = {CONF_RGB_ORDER: "GRB", CONF_IS_RGBW: True, CONF_IS_WRGB: True}
+    with pytest.raises(cv.Invalid, match="cannot both be enabled"):
+        _migrate(config)

tests/unit_tests/components/test_esp32_rmt_led_strip.py

@@ -1,57 +0,0 @@
-import pytest
-
-from esphome.components.esp32_rmt_led_strip.light import (
-    CONF_IS_WRGB,
-    CONF_RGBW_ORDER,
-    _split_rgbw_order,
-    _validate_rgbw_order,
-    _validate_rgbw_order_exclusivity,
-)
-import esphome.config_validation as cv
-from esphome.const import CONF_IS_RGBW
-
-
-def test_validate_rgbw_order() -> None:
-    assert _validate_rgbw_order("rwgb") == "RWGB"
-
-
-@pytest.mark.parametrize("rgbw_order", ["RGB", "RRGB", "RGBWW"])
-def test_validate_rgbw_order_rejects_invalid_order(rgbw_order: str) -> None:
-    with pytest.raises(cv.Invalid, match="permutation of RGBW"):
-        _validate_rgbw_order(rgbw_order)
-
-
-@pytest.mark.parametrize(
-    ("rgbw_order", "expected"),
-    [
-        ("WRGB", ("RGB", 0)),
-        ("RWGB", ("RGB", 1)),
-        ("GWRB", ("GRB", 1)),
-        ("RGBW", ("RGB", 3)),
-    ],
-)
-def test_split_rgbw_order(rgbw_order: str, expected: tuple[str, int]) -> None:
-    assert _split_rgbw_order(rgbw_order) == expected
-
-
-@pytest.mark.parametrize("conflict", [CONF_IS_RGBW, CONF_IS_WRGB])
-def test_rgbw_order_is_mutually_exclusive(conflict: str) -> None:
-    with pytest.raises(cv.Invalid, match="cannot be used with"):
-        _validate_rgbw_order_exclusivity(
-            {
-                CONF_RGBW_ORDER: "RGBW",
-                CONF_IS_RGBW: conflict == CONF_IS_RGBW,
-                CONF_IS_WRGB: conflict == CONF_IS_WRGB,
-            }
-        )
-
-
-@pytest.mark.parametrize("legacy_option", [CONF_IS_RGBW, CONF_IS_WRGB])
-def test_rgbw_order_allows_disabled_legacy_options(legacy_option: str) -> None:
-    config = {
-        CONF_RGBW_ORDER: "RGBW",
-        CONF_IS_RGBW: False,
-        CONF_IS_WRGB: False,
-    }
-    config[legacy_option] = False
-    assert _validate_rgbw_order_exclusivity(config) is config

tests/unit_tests/components/test_web_server.py

@@ -0,0 +1,150 @@
+"""Tests for the web_server AP mode helpers."""
+
+import logging
+
+import pytest
+
+from esphome.components.web_server import (
+    _final_validate_ap_mode,
+    serve_captive,
+    serve_local,
+)
+from esphome.const import (
+    CONF_AP,
+    CONF_LOCAL,
+    CONF_NETWORKS,
+    CONF_PORT,
+    CONF_SSID,
+    CONF_VERSION,
+    CONF_WIFI,
+)
+import esphome.final_validate as fv
+
+AP_ONLY = {CONF_AP: {}}
+AP_FALLBACK = {CONF_AP: {}, CONF_NETWORKS: [{CONF_SSID: "x"}]}
+STA_ONLY = {CONF_NETWORKS: [{CONF_SSID: "x"}]}
+
+
+@pytest.mark.parametrize(
+    ("web_server_config", "wifi_config", "expected"),
+    [
+        # AP only: embed the interface, the AP has no internet.
+        ({CONF_VERSION: 2}, AP_ONLY, True),
+        ({CONF_VERSION: 3}, AP_ONLY, True),
+        # Explicit setting always wins.
+        ({CONF_VERSION: 2, CONF_LOCAL: False}, AP_ONLY, False),
+        ({CONF_VERSION: 2, CONF_LOCAL: True}, STA_ONLY, True),
+        # AP fallback, no AP, no wifi, or version 1 (no local mode): hosted page.
+        ({CONF_VERSION: 2}, AP_FALLBACK, False),
+        ({CONF_VERSION: 2}, STA_ONLY, False),
+        ({CONF_VERSION: 2}, None, False),
+        ({CONF_VERSION: 1}, AP_ONLY, False),
+    ],
+)
+def test_serve_local(
+    web_server_config: dict, wifi_config: dict | None, expected: bool
+) -> None:
+    """The interface is embedded for AP only WiFi unless local is set explicitly."""
+    assert serve_local(web_server_config, wifi_config) is expected
+
+
+@pytest.mark.parametrize(
+    ("web_server_config", "full_config", "expected"),
+    [
+        # AP only: local is implied, web_server is the captive portal.
+        ({CONF_VERSION: 2}, {CONF_WIFI: AP_ONLY}, True),
+        # Captive portal probes only work on port 80.
+        ({CONF_VERSION: 2, CONF_PORT: 8080}, {CONF_WIFI: AP_ONLY}, False),
+        # AP fallback needs an explicit local: true to be captive.
+        ({CONF_VERSION: 2}, {CONF_WIFI: AP_FALLBACK}, False),
+        ({CONF_VERSION: 2, CONF_LOCAL: True}, {CONF_WIFI: AP_FALLBACK}, True),
+        # captive_portal owns the role when configured.
+        ({CONF_VERSION: 2}, {CONF_WIFI: AP_ONLY, "captive_portal": {}}, False),
+        # No AP, no wifi, hosted page, or version 1: never captive.
+        ({CONF_VERSION: 2, CONF_LOCAL: True}, {CONF_WIFI: STA_ONLY}, False),
+        ({CONF_VERSION: 2, CONF_LOCAL: True}, {}, False),
+        ({CONF_VERSION: 2, CONF_LOCAL: False}, {CONF_WIFI: AP_ONLY}, False),
+        ({CONF_VERSION: 1}, {CONF_WIFI: AP_ONLY}, False),
+    ],
+)
+def test_serve_captive(
+    web_server_config: dict, full_config: dict, expected: bool
+) -> None:
+    web_server_config.setdefault(CONF_PORT, 80)
+    assert serve_captive(web_server_config, full_config) is expected
+
+
+@pytest.mark.parametrize(
+    ("web_server_config", "expect_warning"),
+    [
+        # Explicit local: false on an AP only device: the hosted page will stay blank.
+        ({CONF_VERSION: 2, CONF_PORT: 80, CONF_LOCAL: False}, True),
+        # Default: embedded and captive, nothing to warn about.
+        ({CONF_VERSION: 2, CONF_PORT: 80}, False),
+    ],
+)
+def test_final_validate_ap_mode_warns_for_hosted_page(
+    web_server_config: dict, expect_warning: bool, caplog: pytest.LogCaptureFixture
+) -> None:
+    token = fv.full_config.set({"web_server": web_server_config, CONF_WIFI: AP_ONLY})
+    try:
+        with caplog.at_level(logging.WARNING):
+            _final_validate_ap_mode(web_server_config)
+    finally:
+        fv.full_config.reset(token)
+    assert ("stays blank" in caplog.text) is expect_warning
+
+
+def test_final_validate_ap_mode_warns_for_non_default_port(
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    """Captive portal detection needs port 80; other ports get a hint, not captive mode."""
+    config = {CONF_VERSION: 2, CONF_PORT: 8080}
+    token = fv.full_config.set({"web_server": config, CONF_WIFI: AP_ONLY})
+    try:
+        with caplog.at_level(logging.WARNING):
+            _final_validate_ap_mode(config)
+    finally:
+        fv.full_config.reset(token)
+    assert "cannot open automatically" in caplog.text
+    assert "http://192.168.4.1:8080/" in caplog.text
+
+
+def test_final_validate_ap_mode_port_warning_uses_manual_ip(
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    """The manual URL in the port warning honors wifi.ap.manual_ip."""
+    from esphome.const import CONF_MANUAL_IP, CONF_STATIC_IP
+
+    config = {CONF_VERSION: 2, CONF_PORT: 8080}
+    wifi = {CONF_AP: {CONF_MANUAL_IP: {CONF_STATIC_IP: "10.0.0.1"}}}
+    token = fv.full_config.set({"web_server": config, CONF_WIFI: wifi})
+    try:
+        with caplog.at_level(logging.WARNING):
+            _final_validate_ap_mode(config)
+    finally:
+        fv.full_config.reset(token)
+    assert "http://10.0.0.1:8080/" in caplog.text
+
+
+@pytest.mark.parametrize(
+    ("wifi_config", "expected"),
+    [
+        # Explicit local: true on a fallback AP: announce the captive fallback role.
+        (AP_FALLBACK, "fallback access point"),
+        # Explicit local: true on AP only skips the implied-local info; still announce.
+        (AP_ONLY, "captive portal while the access point"),
+    ],
+)
+def test_final_validate_ap_mode_informs_explicit_local_captive(
+    wifi_config: dict, expected: str, caplog: pytest.LogCaptureFixture
+) -> None:
+    """Explicit local: true logs that web_server becomes the captive portal."""
+    config = {CONF_VERSION: 2, CONF_PORT: 80, CONF_LOCAL: True}
+    token = fv.full_config.set({"web_server": config, CONF_WIFI: wifi_config})
+    try:
+        with caplog.at_level(logging.INFO):
+            _final_validate_ap_mode(config)
+    finally:
+        fv.full_config.reset(token)
+    assert expected in caplog.text

tests/unit_tests/test_config_normalization.py

@@ -7,7 +7,7 @@ from unittest.mock import MagicMock, Mock, patch
 
 import pytest
 
-from esphome import config, yaml_util
+from esphome import config, config_validation as cv, yaml_util
 from esphome.core import CORE, AutoLoad
 from esphome.types import ConfigType
 
@@ -127,12 +127,14 @@ def _run_load_step(
     domain: str,
     conf: object,
     migrate: Callable[[ConfigType], list | None] | None,
+    expand: Callable[[list], list] | None = None,
 ) -> config.Config:
-    """Run a LoadValidationStep for a platform component with a given migrate hook."""
+    """Run a LoadValidationStep for a platform component with given hooks."""
     component = Mock()
     component.is_platform_component = True
     component.multi_conf_no_default = False
     component.legacy_config_migrate = migrate
+    component.expand_platform_config = expand
 
     result = config.Config()
     with (
@@ -197,6 +199,124 @@ def test_legacy_migrate_skipped_for_autoload() -> None:
     assert result["image"] == [auto]
 
 
+# ---------------------------------------------------------------------------
+# EXPAND_PLATFORM_CONFIG hook on LoadValidationStep -- permanent counterpart
+# to legacy_config_migrate; runs after legacy migration/list normalization.
+# ---------------------------------------------------------------------------
+
+
+def test_expand_hook_rewrites_conf() -> None:
+    """A config the expand hook rewrites is replaced with the expanded list."""
+    expanded = [{"platform": "file", "id": "a"}, {"platform": "file", "id": "b"}]
+    expand = Mock(return_value=expanded)
+
+    result = _run_load_step("image", [{"platform": "file", "id": "a"}], None, expand)
+
+    expand.assert_called_once_with([{"platform": "file", "id": "a"}])
+    assert result["image"] == expanded
+
+
+def test_expand_hook_absent_is_noop() -> None:
+    """A platform component without the hook is left as normalized by the
+    existing list-wrapping logic."""
+    result = _run_load_step("image", [{"platform": "file", "id": "a"}], None, None)
+
+    assert result["image"] == [{"platform": "file", "id": "a"}]
+
+
+def test_expand_hook_runs_after_legacy_migrate() -> None:
+    """The expand hook sees the already-migrated list, not the raw legacy conf."""
+    migrated = [{"platform": "file", "id": "a"}]
+    migrate = Mock(return_value=migrated)
+    expand = Mock(side_effect=lambda conf: conf)
+
+    _run_load_step("image", [{"id": "a", "file": "x.png"}], migrate, expand)
+
+    expand.assert_called_once_with(migrated)
+
+
+def test_expand_hook_skipped_for_non_dict_entry() -> None:
+    """Malformed entries are left alone; the hook only sees `platform:`-tagged dicts."""
+    expand = Mock(side_effect=lambda conf: conf)
+
+    result = _run_load_step("image", ["not-a-dict"], None, expand)
+
+    expand.assert_not_called()
+    assert result["image"] == ["not-a-dict"]
+
+
+def test_expand_hook_skipped_for_entry_missing_platform_key() -> None:
+    """A dict entry missing the `platform:` key is left alone -- the normal
+    per-entry error reporting further down catches this case instead."""
+    expand = Mock(side_effect=lambda conf: conf)
+
+    result = _run_load_step("image", [{"id": "a"}], None, expand)
+
+    expand.assert_not_called()
+    assert result["image"] == [{"id": "a"}]
+
+
+def test_expand_hook_skipped_for_autoload() -> None:
+    """A non-empty AutoLoad reaching the hook stage is left alone."""
+    expand = Mock(side_effect=lambda conf: conf)
+    auto = AutoLoad()
+    auto["id"] = "a"
+
+    result = _run_load_step("image", auto, None, expand)
+
+    expand.assert_not_called()
+    assert result["image"] == [auto]
+
+
+def test_expand_hook_runs_when_all_entries_are_platform_tagged_dicts() -> None:
+    """The guard does not block the normal, well-formed case."""
+    expand = Mock(side_effect=lambda conf: conf)
+    conf = [{"platform": "file", "id": "a"}, {"platform": "animation", "id": "b"}]
+
+    result = _run_load_step("image", conf, None, expand)
+
+    expand.assert_called_once_with(conf)
+    assert result["image"] == conf
+
+
+def test_expand_hook_invalid_reports_single_error_at_domain_path() -> None:
+    """A `cv.Invalid` from the hook is reported once with the domain path prepended; no further validation runs."""
+    expand = Mock(side_effect=cv.Invalid("bad shape"))
+    pre_expand_conf = [{"platform": "file", "id": "a"}]
+
+    result = _run_load_step("image", pre_expand_conf, None, expand)
+
+    assert len(result.errors) == 1
+    assert result.errors[0].path == ["image"]
+    assert "bad shape" in str(result.errors[0])
+    assert result["image"] == pre_expand_conf
+
+
+def test_expand_hook_final_external_invalid_reports_without_path_prepend() -> None:
+    """`cv.FinalExternalInvalid` keeps its already-resolved path (no domain path prepended)."""
+    already_resolved_error = cv.FinalExternalInvalid(
+        "bad shape", path=["image", 3, "files"]
+    )
+    expand = Mock(side_effect=already_resolved_error)
+    pre_expand_conf = [{"platform": "file", "id": "a"}]
+
+    result = _run_load_step("image", pre_expand_conf, None, expand)
+
+    assert len(result.errors) == 1
+    assert result.errors[0] is already_resolved_error
+    assert result.errors[0].path == ["image", 3, "files"]
+    assert result["image"] == pre_expand_conf
+
+
+def test_expand_hook_non_list_return_raises_type_error() -> None:
+    """A non-list return is a component bug: it escapes as an uncaught TypeError
+    (explicit raise survives -O/-OO)."""
+    expand = Mock(return_value={"not": "a list"})
+
+    with pytest.raises(TypeError, match="must return a list"):
+        _run_load_step("image", [{"platform": "file", "id": "a"}], None, expand)
+
+
 def _write_merge_conflict_config(tmp_path: Path, *, suppress: bool) -> Path:
     """Create a config where two `<<` includes both define `logger:`.
 

tests/unit_tests/test_platformio_toolchain.py

@@ -2,7 +2,7 @@
 
 # pylint: disable=protected-access
 
-from collections.abc import Generator
+from collections.abc import Callable, Generator
 from contextlib import contextmanager
 from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 import json
@@ -437,6 +437,7 @@ def test_ccache_env_enabled_by_default(setup_core: Path) -> None:
         env = toolchain._ccache_env()
 
     assert env["ESPHOME_CCACHE_ENABLE"] == "1"
+    assert env["ESPHOME_CCACHE_PATH"] == "/usr/bin/ccache"
     assert env["CCACHE_BASEDIR"] == str((setup_core / "build" / "test").resolve())
     assert env["CCACHE_DIR"].endswith("platformio-ccache")
     assert env["CCACHE_NOHASHDIR"] == "true"
@@ -446,17 +447,35 @@ def test_ccache_env_enabled_by_default(setup_core: Path) -> None:
     assert "ESPHOME_CCACHE_ENABLE" not in os.environ
 
 
-def test_ccache_env_disabled_without_binary(setup_core: Path) -> None:
-    """Ccache stays off when the binary is not on PATH."""
+@pytest.mark.parametrize(
+    ("env_vars", "expect_warning"),
+    [
+        pytest.param({}, False, id="default"),
+        pytest.param({"ESPHOME_CCACHE_ENABLE": "1"}, True, id="forced-on"),
+    ],
+)
+def test_ccache_env_disabled_without_binary(
+    setup_core: Path,
+    caplog: pytest.LogCaptureFixture,
+    env_vars: dict[str, str],
+    expect_warning: bool,
+) -> None:
+    """Ccache stays off when the binary is not on PATH, even when forced on.
+
+    A deliberate opt-in that finds no binary is downgraded with a warning so
+    the user can tell why it had no effect; the default path stays quiet.
+    """
     CORE.build_path = setup_core / "build" / "test"
 
     with (
-        patch.dict(os.environ, {}, clear=True),
+        patch.dict(os.environ, env_vars, clear=True),
         patch.object(toolchain.shutil, "which", return_value=None),
+        caplog.at_level("WARNING"),
     ):
         env = toolchain._ccache_env()
 
     assert env == {"ESPHOME_CCACHE_ENABLE": "0"}
+    assert ("no ccache binary is on PATH" in caplog.text) is expect_warning
 
 
 @pytest.mark.parametrize(
@@ -489,14 +508,47 @@ def test_ccache_env_forced_on_skips_probe(setup_core: Path) -> None:
 
     with (
         patch.dict(os.environ, {"ESPHOME_CCACHE_ENABLE": "1"}, clear=True),
+        patch.object(toolchain.shutil, "which", return_value="/usr/bin/ccache"),
         patch.object(toolchain.subprocess, "run") as mock_probe,
     ):
         env = toolchain._ccache_env()
 
     assert env["ESPHOME_CCACHE_ENABLE"] == "1"
+    # The binary's location is still handed to the build script.
+    assert env["ESPHOME_CCACHE_PATH"] == "/usr/bin/ccache"
     mock_probe.assert_not_called()
 
 
+def test_ccache_env_strips_win_long_path_prefix(setup_core: Path) -> None:
+    r"""A ``\\?\`` ccache path from PATH is exported without the prefix.
+
+    That is the shape ESPHome Desktop puts on PATH (#18399); see ``_ccache_env``.
+    """
+    CORE.build_path = setup_core / "build" / "test"
+    prefixed = (
+        "\\\\?\\C:\\Users\\jesse\\AppData\\Local\\ESPHome Device Builder"
+        "\\ccache\\ccache.exe"
+    )
+    stripped = (
+        "C:\\Users\\jesse\\AppData\\Local\\ESPHome Device Builder\\ccache\\ccache.exe"
+    )
+
+    with (
+        patch.dict(os.environ, {}, clear=True),
+        # shutil.which is patched, so the win32 code path of the real
+        # implementation (which crashes on a POSIX host) is never reached.
+        patch("esphome.platformio.toolchain.sys.platform", "win32"),
+        patch.object(toolchain.shutil, "which", return_value=prefixed),
+        patch.object(toolchain.subprocess, "run") as mock_probe,
+    ):
+        env = toolchain._ccache_env()
+
+    assert env["ESPHOME_CCACHE_ENABLE"] == "1"
+    assert env["ESPHOME_CCACHE_PATH"] == stripped
+    # The probe validates the exact string the build will execute.
+    assert mock_probe.call_args[0][0] == [stripped, "--version"]
+
+
 def test_ccache_env_opt_out(setup_core: Path) -> None:
     """ESPHOME_CCACHE_ENABLE=0 disables ccache even with the binary present."""
     CORE.build_path = setup_core / "build" / "test"
@@ -516,7 +568,7 @@ def test_ccache_env_normalizes_enable_value(setup_core: Path) -> None:
 
     with (
         patch.dict(os.environ, {"ESPHOME_CCACHE_ENABLE": "yes"}, clear=True),
-        patch.object(toolchain.shutil, "which", return_value=None),
+        patch.object(toolchain.shutil, "which", return_value="/usr/bin/ccache"),
     ):
         env = toolchain._ccache_env()
 
@@ -563,8 +615,10 @@ def test_run_platformio_cli_passes_ccache_env_to_subprocess_only(
 
         env = mock_run_external_process.call_args[1]["env"]
         assert env["ESPHOME_CCACHE_ENABLE"] == "1"
+        assert env["ESPHOME_CCACHE_PATH"] == "/usr/bin/ccache"
         assert env["CCACHE_BASEDIR"] == str((setup_core / "build" / "test").resolve())
         assert "ESPHOME_CCACHE_ENABLE" not in os.environ
+        assert "ESPHOME_CCACHE_PATH" not in os.environ
         assert "CCACHE_BASEDIR" not in os.environ
 
 
@@ -613,6 +667,182 @@ def test_copy_ccache_script(setup_core: Path) -> None:
     assert dest.read_text() == source.read_text()
 
 
+class _FakeSConsEnv(dict):
+    """Just enough of a SCons construction environment for ccache.py."""
+
+    def Replace(self, **kwargs: object) -> None:  # noqa: N802
+        self.update(kwargs)
+
+
+def _load_ccache_script(
+    env_vars: dict[str, str], original_spawn: Callable[..., int] | None = None
+) -> tuple[_FakeSConsEnv, Callable[..., int]]:
+    """Run ccache.py.script against a fake SCons env and return (env, original SPAWN)."""
+    if original_spawn is None:
+        original_spawn = Mock(name="original_spawn", return_value=0)
+    scons_env = _FakeSConsEnv(SPAWN=original_spawn)
+    source = (Path(toolchain.__file__).parent / "ccache.py.script").read_text()
+    with patch.dict(os.environ, env_vars, clear=True):
+        exec(  # noqa: S102
+            compile(source, "ccache.py", "exec"),
+            {"Import": lambda *_names: None, "env": scons_env},
+        )
+    return scons_env, original_spawn
+
+
+def _scons_win32_escape(x: str) -> str:
+    """Copy of ``SCons.Platform.win32.escape``: quote, guarding a trailing backslash."""
+    if x[-1] == "\\":
+        x = x + "\\"
+    return '"' + x + '"'
+
+
+def test_ccache_script_wraps_compiles_with_exported_path() -> None:
+    """The SCons script uses ESPHOME_CCACHE_PATH as given, without a PATH lookup."""
+    ccache_path = "C:\\Users\\jesse\\ESPHome Device Builder\\ccache\\ccache.exe"
+    scons_env, original_spawn = _load_ccache_script(
+        {"ESPHOME_CCACHE_ENABLE": "1", "ESPHOME_CCACHE_PATH": ccache_path}
+    )
+    spawn = scons_env["SPAWN"]
+    assert spawn is not original_spawn
+
+    # A compile step is routed through ccache, with the same path used for
+    # the program and (escaped) as the first argument.
+    compile_args = ["xtensa-lx106-elf-g++", "-o", "main.o", "-c", "main.cpp"]
+    spawn("cmd.exe", _scons_win32_escape, "xtensa-lx106-elf-g++", compile_args, {})
+    original_spawn.assert_called_once_with(
+        "cmd.exe",
+        _scons_win32_escape,
+        ccache_path,
+        [_scons_win32_escape(ccache_path), *compile_args],
+        {},
+    )
+
+    # Link steps pass through untouched.
+    original_spawn.reset_mock()
+    link_args = ["xtensa-lx106-elf-g++", "-o", "firmware.elf", "main.o"]
+    spawn("cmd.exe", _scons_win32_escape, "xtensa-lx106-elf-g++", link_args, {})
+    original_spawn.assert_called_once_with(
+        "cmd.exe", _scons_win32_escape, "xtensa-lx106-elf-g++", link_args, {}
+    )
+
+
+@pytest.mark.parametrize(
+    "env_vars",
+    [
+        pytest.param({"ESPHOME_CCACHE_ENABLE": "0"}, id="disabled"),
+        pytest.param({"ESPHOME_CCACHE_ENABLE": "1"}, id="enabled-without-path"),
+        pytest.param({}, id="unset"),
+    ],
+)
+def test_ccache_script_leaves_spawn_alone_without_path(
+    env_vars: dict[str, str],
+) -> None:
+    """Without both the enable flag and a path, SPAWN is not replaced."""
+    scons_env, original_spawn = _load_ccache_script(env_vars)
+    assert scons_env["SPAWN"] is original_spawn
+
+
+def _scons_win32_spawn(
+    sh: str, escape: Callable[[str], str], cmd: str, args: list[str], env: dict
+) -> int:
+    r"""Mirror of ``SCons.Platform.win32.spawn``: every command runs via ``cmd.exe /C``.
+
+    SCons is not importable in the test environment (PlatformIO fetches it at
+    build time), so the lines that matter are mirrored here. The command line
+    SCons hands ``os.spawnve`` goes to ``CreateProcess`` via ``subprocess``
+    instead (identical on Windows, where a string passes through untouched);
+    ``spawnve`` itself crashes inside pytest.
+    """
+    return subprocess.run(
+        " ".join([sh, "/C", escape(" ".join(args))]), env=env, check=False
+    ).returncode
+
+
+_MARKER_ENV = "ESPHOME_TEST_CCACHE_MARKER"
+# Stands in for a compile: the "ccache" is really the Python interpreter, and
+# the compile "flags" make it write a marker file so the test can tell whether
+# the wrapped command actually ran to completion.
+_FAKE_COMPILE_ARGS = [
+    "-c",
+    f"import os, pathlib; pathlib.Path(os.environ['{_MARKER_ENV}']).write_text('compiled')",
+]
+
+
+def _spawn_fake_compile_via_cmd_exe(scons_env: _FakeSConsEnv, marker: Path) -> int:
+    """Run one wrapped compile step the way SCons does on Windows."""
+    child_env = {**os.environ, _MARKER_ENV: str(marker)}
+    return scons_env["SPAWN"](
+        os.environ.get("COMSPEC", "cmd.exe"),
+        _scons_win32_escape,
+        "xtensa-lx106-elf-gcc",
+        [_scons_win32_escape(arg) if " " in arg else arg for arg in _FAKE_COMPILE_ARGS],
+        child_env,
+    )
+
+
+_WINDOWS_ONLY = pytest.mark.skipif(
+    sys.platform != "win32", reason="drives cmd.exe, which SCons uses only on Windows"
+)
+
+
+@_WINDOWS_ONLY
+def test_ccache_env_real_probe_runs_stripped_path(setup_core: Path) -> None:
+    r"""With a ``\\?\`` which result, the real probe runs the stripped binary.
+
+    The probe therefore validates the exact string the build will execute
+    through ``cmd.exe``; probing the verbatim path instead would pass even
+    when the stripped path is unusable (``CreateProcess`` accepts
+    extended-length paths, ``cmd.exe`` does not).
+    """
+    CORE.build_path = setup_core / "build" / "test"
+    assert not sys.executable.startswith("\\\\?\\")
+
+    with (
+        patch.dict(os.environ, {}, clear=False),
+        patch.object(
+            toolchain.shutil, "which", return_value="\\\\?\\" + sys.executable
+        ),
+    ):
+        os.environ.pop("ESPHOME_CCACHE_ENABLE", None)
+        env = toolchain._ccache_env()
+
+    assert env["ESPHOME_CCACHE_ENABLE"] == "1"
+    assert env["ESPHOME_CCACHE_PATH"] == sys.executable
+
+
+@_WINDOWS_ONLY
+@pytest.mark.parametrize(
+    ("prefix", "expect_ok"),
+    [
+        pytest.param("", True, id="stripped-path-compiles"),
+        pytest.param("\\\\?\\", False, id="verbatim-path-fails"),
+    ],
+)
+def test_ccache_wrapper_through_cmd_exe(
+    tmp_path: Path, prefix: str, expect_ok: bool
+) -> None:
+    r"""End to end through ``cmd.exe``: the exported path works, a ``\\?\`` one does not.
+
+    The interpreter stands in for ccache; the spawn mirrors SCons on Windows.
+    The failing case is the mechanism behind #18399 ("The system cannot find
+    the path specified." on every compile step); should it ever start passing,
+    ``cmd.exe`` learned extended-length paths and the strip is no longer needed.
+    """
+    marker = tmp_path / "compiled.txt"
+    scons_env, _ = _load_ccache_script(
+        {"ESPHOME_CCACHE_ENABLE": "1", "ESPHOME_CCACHE_PATH": prefix + sys.executable},
+        original_spawn=_scons_win32_spawn,
+    )
+    assert scons_env["SPAWN"] is not _scons_win32_spawn
+
+    rc = _spawn_fake_compile_via_cmd_exe(scons_env, marker)
+    assert (rc == 0) is expect_ok
+    assert marker.exists() is expect_ok
+    if expect_ok:
+        assert marker.read_text() == "compiled"
+
+
 @pytest.mark.parametrize(
     ("platform", "input_path", "expected"),
     [

tests/unit_tests/test_vscode.py

@@ -3,6 +3,8 @@ from pathlib import Path
 from unittest.mock import Mock, patch
 
 from esphome import vscode
+import esphome.config_validation as cv
+from esphome.core import EsphomeError
 
 
 def _run_repl_test(input_data):
@@ -126,3 +128,67 @@ packages:
     assert range["start_col"] == 2
     assert range["end_line"] == 1
     assert range["end_col"] == 7
+
+
+def _explode(*_args: object, **_kwargs: object) -> None:
+    raise AttributeError("'NoneType' object has no attribute 'get'")
+
+
+def test_unexpected_error_reports_origin() -> None:
+    source_path = str(Path("dir_path", "x.yaml"))
+    with patch("esphome.vscode.validate_config", _explode):
+        output_lines = _run_repl_test(
+            [
+                _validate(source_path),
+                _file_response("""esphome:
+  name: test1
+"""),
+            ]
+        )
+
+    result = json.loads(output_lines[-1])
+    assert result["validation_errors"] == []
+    (error,) = result["yaml_errors"]
+    assert error["message"].startswith(
+        "Unexpected error while validating: AttributeError: "
+        "'NoneType' object has no attribute 'get' ("
+    )
+    assert "test_vscode.py" in error["message"]
+    assert error["message"].endswith(" in _explode)")
+
+
+def test_esphome_error_stays_plain() -> None:
+    source_path = str(Path("dir_path", "x.yaml"))
+    with patch("esphome.vscode.validate_config", side_effect=EsphomeError("boom")):
+        output_lines = _run_repl_test(
+            [
+                _validate(source_path),
+                _file_response("""esphome:
+  name: test1
+"""),
+            ]
+        )
+
+    result = json.loads(output_lines[-1])
+    assert result["yaml_errors"] == [{"message": "boom"}]
+
+
+def test_invalid_stays_plain() -> None:
+    source_path = str(Path("dir_path", "x.yaml"))
+    with patch("esphome.vscode.validate_config", side_effect=cv.Invalid("bad value")):
+        output_lines = _run_repl_test(
+            [
+                _validate(source_path),
+                _file_response("""esphome:
+  name: test1
+"""),
+            ]
+        )
+
+    result = json.loads(output_lines[-1])
+    assert result["yaml_errors"] == [{"message": "bad value"}]
+
+
+def test_format_unexpected_error_without_traceback() -> None:
+    message = vscode._format_unexpected_error(ValueError("boom"))
+    assert message == "Unexpected error while validating: ValueError: boom"