Pick the nRF52 ELF layout by SDK version

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.agents/skills/code-review/SKILL.md

@@ -0,0 +1,116 @@
+---
+name: code-review
+description: Review guidance for ESPHome pull requests. Use this when reviewing a pull request that changes ESPHome Python, C++, or component code, to check it against the project's coding conventions, embedded-systems memory rules, testing requirements, and breaking-change policy.
+---
+
+# Reviewing ESPHome pull requests
+
+ESPHome parses YAML into C++ firmware for memory-constrained microcontrollers
+(ESP32, ESP8266, RP2040, LibreTiny). Review changes with that in mind: RAM and
+flash are scarce, and code runs unattended for months.
+
+`AGENTS.md` in the repository root is the full contributor guide and the
+authority when it disagrees with this summary. The developer documentation at
+https://developers.esphome.io explains the component lifecycle and the reasoning
+behind these rules. This skill lists the concrete things worth flagging in a
+review; read `AGENTS.md` for the detail behind any item.
+
+Only raise findings that the diff actually introduces or changes. Do not ask for
+drive-by cleanup of pre-existing code the PR did not touch.
+
+## Memory and embedded constraints (highest value)
+
+Heap allocation after `setup()` is treated as a reliability bug, not a
+performance nit, because it fragments a small shared heap. Flag:
+
+- New heap allocation on a hot path or after setup that could be avoided.
+- `std::vector` where the size is known at compile time (use `std::array`, or
+  `StaticVector<T, N>` when a `push_back` API is needed) or fixed at runtime
+  init (use `FixedVector<T>`).
+- Listener / child-entity registration lists stored as `std::vector`; these have
+  a compile-time-known count and should use `cg.slot_counter()` plus
+  `StaticVector`.
+- `std::vector<uint8_t>` for a byte buffer that never grows: prefer
+  `std::unique_ptr<uint8_t[]>` or `std::array`.
+- `std::map` / `std::set` / `std::unordered_map` for small datasets (1-16
+  elements): a `std::vector` of a small struct with linear search is lighter.
+- `std::deque` anywhere: it allocates 512-byte blocks and should be avoided.
+- `std::string` storing a value set once from config: prefer `StringRef` (the
+  literal already lives in flash).
+- `std::string` / `std::to_string` / string-returning helpers on hot paths where
+  a buffer or view API exists.
+
+## C++ conventions
+
+- Include what you use: a file referencing a symbol must include the header that
+  declares it, even if it currently arrives transitively. New or changed uses of
+  a symbol need the matching include.
+- Prefix all member access with `this->`.
+- Naming: `lower_snake_case` for functions/methods/variables, `UpperCamelCase`
+  for classes/structs/enums, `UPPER_SNAKE_CASE` for namespace-scope constants,
+  trailing underscore on protected/private fields.
+- `enum class` values must be prefixed with the enum name in `UPPER_SNAKE_CASE`
+  (e.g. `UARTFlushResult::UART_FLUSH_RESULT_SUCCESS`). Bare names like `SUCCESS`,
+  `FAIL`, or `OK` collide with SDK macros on some platforms and break the build.
+- Prefer `const`/`enum` over `#define`; `#define` is only for conditional
+  compilation and code-generation sizes.
+- Never call `millis()` in a `loop()` body; use
+  `App.get_loop_component_start_time()`. A rate-limit gate below ~16 ms (the loop
+  period) does nothing.
+- Pick the timing primitive by cadence: gated `loop()` under 250 ms,
+  `set_interval` at 500 ms and above.
+- Do not override a base method to return the value it already returns (e.g.
+  `get_setup_priority()` returning `setup_priority::DATA`).
+- Wrap string literals passed as printf `%s` args in `LOG_STR_LITERAL()`.
+- Required, invariant dependencies should be constructor parameters, not setters.
+- Callback registration methods must be templated (`template<typename F>`), not
+  typed as `std::function`, so lightweight forwarders avoid a heap allocation.
+- Two-space indent, `using` over `typedef`, wrap at 120 columns.
+
+## Python conventions
+
+- Type-annotate every new function signature (params and return), new dataclass
+  fields, and new module-level variables. Import `ConfigType` from
+  `esphome.types`.
+- Use the walrus operator to avoid a double lookup, e.g.
+  `if (blah := config.get(CONF_BLAH)) is not None:`.
+- Reuse existing validators from `config_validation.py` (`cv.rename_key`,
+  `cv.has_exactly_one_key`, etc.) via `cv.All(...)` instead of hand-rolling.
+- `esphome/const.py` is frozen: no new `CONF_` constants there. Define them in
+  the component's own `.py`, or in `esphome/components/const/__init__.py` when
+  shared. The same constant defined in three or more component files fails CI.
+- State that must persist during code generation goes in `CORE.data` namespaced
+  under the component `DOMAIN` (a `@dataclass`), not module-level mutable globals.
+- Prefer callback-based triggers via `build_callback_automation()`; only use a
+  `Trigger<Ts...>` subclass when the forwarder needs mutable state.
+
+## Testing and coverage
+
+- New and changed lines and branches need test coverage, including defensive
+  early-returns, error paths, and no-op guards. A mocked-out function is not
+  covered; exercise the real call path too.
+- Component YAML tests live in `tests/components/<component>/`. Never define
+  buses (uart, i2c, spi, modbus) directly in a test file: pull them from
+  `tests/test_build_components/common/` through dict-style `packages:` so CI can
+  group builds. List-style packages or top-level merge keys block grouping.
+- Config-only checks use the `validate.*.yaml` prefix; compiled checks use
+  `test.*.yaml`.
+
+## Breaking changes and public API
+
+- Base classes under `esphome/core/` and documented config options are public
+  API. Undocumented `public` members of a component are internal.
+- A breaking change needs justification, a migration path in the PR description,
+  and a deprecation window where feasible (`ESPDEPRECATED` in C++,
+  `cv.rename_key(..., removed_in=...)` in Python). Changing a codegen-injected
+  lambda signature is not a breaking change.
+
+## Process and PR hygiene
+
+- PR titles start with a `[tag]` prefix: the component name (e.g. `[uart] ...`)
+  or `[core]` for shared code.
+- Prose in docs, comments, and commit messages should be plain English. Keep
+  inline comments short and only where the code is not self-explanatory; do not
+  restate what the code says.
+- Verify the PR fills out `.github/PULL_REQUEST_TEMPLATE.md` and adds
+  `CODEOWNERS` entries for a new component.

.claude/settings.json

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

.claude/skills

@@ -0,0 +1 @@
+../.agents/skills

.devcontainer/Dockerfile

@@ -31,7 +31,4 @@ RUN \
     platformio settings set enable_telemetry No \
     && platformio settings set check_platformio_interval 1000000
 
-COPY script/platformio_install_deps.py platformio.ini ./
-RUN ./platformio_install_deps.py platformio.ini --libraries --platforms --tools
-
 WORKDIR /workspaces

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -9,6 +9,29 @@ body:
         If you have a feature request or enhancement, please [request them here instead][fr].
 
         [fr]: https://github.com/orgs/esphome/discussions
+  - type: markdown
+    attributes:
+      value: |
+        ## Use of AI in bug reports
+
+        AI tools are good at carrying out well-defined tasks, but they are not good at troubleshooting.
+        Please do NOT paste an AI-generated wall of text into the issue template - if the AI hasn't solved
+        your problem, its wild guesses are not likely to help.
+
+        Please DO include your own words and observations, compile/boot logs, and
+        especially a minimal reproducible example of your YAML configuration that demonstrates the problem.
+
+        It is however quite acceptable to use AI to translate your *own* report,
+        if you aren't a competent English speaker.
+
+        If you really think it will be useful to include an AI's analysis, preferably wrap it in a `<details>` block which will be collapsed by default.
+
+        If you are using AI to help solve a problem, rather than asking it to speculate about what the problem is,
+        it can be more useful to ask it to create a step-by-step troubleshooting procedure.
+        AI is also useful for generating boilerplate code, such as a minimal reproducible example of your YAML
+        configuration that demonstrates the problem.
+
+        Used properly, AI can be a useful tool to help you solve your problem, but don't let it get in the way.
   - type: textarea
     validations:
       required: true

.github/actions/build-image/action.yaml

@@ -42,7 +42,7 @@ runs:
 
     - name: Build and push to ghcr by digest
       id: build-ghcr
-      uses: docker/build-push-action@53b7df96c91f9c12dcc8a07bcb9ccacbed38856a # v7.3.0
+      uses: docker/build-push-action@c3c9e263c25d99ce0380d002d59b67737d91b0dc # v7.4.0
       env:
         DOCKER_BUILD_SUMMARY: false
         DOCKER_BUILD_RECORD_UPLOAD: false
@@ -67,7 +67,7 @@ runs:
 
     - name: Build and push to dockerhub by digest
       id: build-dockerhub
-      uses: docker/build-push-action@53b7df96c91f9c12dcc8a07bcb9ccacbed38856a # v7.3.0
+      uses: docker/build-push-action@c3c9e263c25d99ce0380d002d59b67737d91b0dc # v7.4.0
       env:
         DOCKER_BUILD_SUMMARY: false
         DOCKER_BUILD_RECORD_UPLOAD: false

.github/actions/cache-clang-tidy-idedata/action.yml

@@ -0,0 +1,50 @@
+name: Cache clang-tidy idedata
+description: >
+  Cache the clang-tidy idedata and the headers it references under .temp
+  (headers only, about 30MB per env). Run after restore-python and cache-esp-idf.
+inputs:
+  environment:
+    description: 'clang-tidy environment (e.g. esp32-idf-tidy).'
+    required: true
+runs:
+  using: composite
+  steps:
+    - name: Compute cache key
+      id: key
+      shell: bash
+      run: |
+        . venv/bin/activate
+        [ -n "${{ inputs.environment }}" ] || { echo "::error::cache-clang-tidy-idedata: 'environment' input is empty"; exit 1; }
+        hash=$(python -c 'import sys; sys.path.insert(0, "script"); from clang_tidy_hash import idedata_cache_hash; print(idedata_cache_hash("${{ inputs.environment }}"))')
+        pyver=$(python -c 'import platform; print(platform.python_version())')
+        # Generating idedata is what installs ESP-IDF; never skip it over a missing
+        # install. This also skips the save, so a dev run that installs ESP-IDF
+        # warms the idedata cache on the next run.
+        if [ -d ~/.esphome-idf/frameworks ]; then
+          echo "skip=false" >> "$GITHUB_OUTPUT"
+        else
+          echo "ESP-IDF install missing, not using the clang-tidy idedata cache"
+          echo "skip=true" >> "$GITHUB_OUTPUT"
+        fi
+        echo "key=${{ runner.os }}-tidy-idedata-${{ inputs.environment }}-$hash-py$pyver" >> "$GITHUB_OUTPUT"
+        {
+          echo "path<<EOF"
+          printf '%s\n' '.temp/idedata-*.json' '.temp/idedata-*.hash'
+          printf '.temp/**/*.%s\n' h hpp hh hxx inc inl ipp tpp
+          echo "EOF"
+        } >> "$GITHUB_OUTPUT"
+    # Mirror cache-esp-idf: write on dev, restore-only on PRs. The post-step
+    # save only runs when the job succeeded, so a failed generation is never saved.
+    # Extend the extension list if a component ships extensionless headers.
+    - name: Cache clang-tidy idedata (write on dev)
+      if: (github.ref == 'refs/heads/dev' || contains(github.event.pull_request.labels.*.name, 'ci-cache-write')) && steps.key.outputs.skip != 'true'
+      uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+      with:
+        path: ${{ steps.key.outputs.path }}
+        key: ${{ steps.key.outputs.key }}
+    - name: Cache clang-tidy idedata (restore-only off dev)
+      if: github.ref != 'refs/heads/dev' && !contains(github.event.pull_request.labels.*.name, 'ci-cache-write') && steps.key.outputs.skip != 'true'
+      uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+      with:
+        path: ${{ steps.key.outputs.path }}
+        key: ${{ steps.key.outputs.key }}

.github/actions/cache-esp-idf/action.yml

@@ -26,6 +26,9 @@ runs:
       # The native-IDF version is pinned in code, not in any file that feeds the
       # other cache keys, so resolve it explicitly. Keying on it means the cache
       # invalidates on a version bump (actions/cache never overwrites a key).
+      # Also key on the Python version: the cached IDF venv links to the
+      # runner's toolcache interpreter and is reinstalled every run after a
+      # runner image bump.
       id: version
       shell: bash
       run: |
@@ -36,19 +39,32 @@ runs:
           version=$(python -c 'from esphome.components.esp32 import ESP_IDF_FRAMEWORK_VERSION_LOOKUP as L; print(L["recommended"])')
         fi
         echo "version=$version" >> "$GITHUB_OUTPUT"
+        echo "python-version=$(python -c 'import platform; print(platform.python_version())')" >> "$GITHUB_OUTPUT"
     # Mirror the adjacent PlatformIO cache: only dev-branch runs write the
     # shared cache (so it lives in the default-branch scope readable by all
     # PRs), and PRs are restore-only -- they never push multi-GB artifacts into
-    # their own scope / the repo quota (e.g. on a version-bump PR).
+    # their own scope / the repo quota (e.g. on a version-bump PR). The
+    # ci-cache-write label lets a PR write into its own scope to test the hit path;
+    # that costs about 1GB of the repo cache quota per run, so remove it when done.
+    # -slim: bump when prune-esp-idf changes what it removes; a key is never overwritten.
     - name: Cache ESP-IDF install (write on dev)
-      if: github.ref == 'refs/heads/dev' && inputs.restore-only != 'true'
+      if: (github.ref == 'refs/heads/dev' || contains(github.event.pull_request.labels.*.name, 'ci-cache-write')) && inputs.restore-only != 'true'
       uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
       with:
         path: ~/.esphome-idf
-        key: ${{ runner.os }}-esphome-idf-${{ steps.version.outputs.version }}
+        key: ${{ runner.os }}-esphome-idf-${{ steps.version.outputs.version }}-py${{ steps.version.outputs.python-version }}-slim
     - name: Cache ESP-IDF install (restore-only off dev)
-      if: github.ref != 'refs/heads/dev' || inputs.restore-only == 'true'
+      if: github.ref != 'refs/heads/dev' && !contains(github.event.pull_request.labels.*.name, 'ci-cache-write') || inputs.restore-only == 'true'
       uses: actions/cache/restore@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
       with:
         path: ~/.esphome-idf
-        key: ${{ runner.os }}-esphome-idf-${{ steps.version.outputs.version }}
+        key: ${{ runner.os }}-esphome-idf-${{ steps.version.outputs.version }}-py${{ steps.version.outputs.python-version }}-slim
+    # Install explicitly so the prune below sees the toolchains on a cache miss
+    # too, instead of the install happening inside the first build step.
+    - name: Install ESP-IDF
+      shell: bash
+      run: |
+        . venv/bin/activate
+        python -c 'from esphome.espidf.framework import check_esp_idf_install; check_esp_idf_install("${{ steps.version.outputs.version }}")'
+    - name: Prune ESP-IDF install
+      uses: ./.github/actions/prune-esp-idf

.github/actions/prune-esp-idf/action.yml

@@ -0,0 +1,34 @@
+name: Prune ESP-IDF install
+description: >
+  Remove the picolibc sysroots (1.1GB of the 3.9GB install) from the native
+  ESP-IDF toolchains; IDF 5.x links newlib. Skipped when an IDF 6 install is
+  present, which links picolibc (see esp32/__init__.py).
+runs:
+  using: composite
+  steps:
+    - name: Prune picolibc
+      shell: bash
+      run: |
+        shopt -s nullglob
+        prefix="${ESPHOME_ESP_IDF_PREFIX:-$HOME/.esphome-idf}"
+        prefix="${prefix/#\~/$HOME}"
+        for fw in "$prefix"/frameworks/*/; do
+          case "$(basename "$fw")" in
+            [6-9].*) echo "IDF $(basename "$fw") installed, keeping picolibc"; exit 0 ;;
+          esac
+        done
+        n=0
+        for dir in "$prefix"/tools/*-esp-elf/*/*-esp-elf/picolibc; do
+          echo "Removing $dir ($(du -sh "$dir" | cut -f1))"
+          rm -rf "$dir"
+          n=$((n + 1))
+        done
+        # The marker rides along in the cache entry so a restored slim tree stays quiet.
+        if [ "$n" -gt 0 ]; then
+          touch "$prefix/.picolibc-pruned"
+        elif [ -d "$prefix/tools" ] && [ ! -f "$prefix/.picolibc-pruned" ]; then
+          echo "::warning::no picolibc sysroots matched under $prefix/tools"
+        fi
+        if [ -d "$prefix" ]; then
+          du -sh "$prefix"
+        fi

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

@@ -32,7 +32,7 @@ runs:
       # detects the activated venv via ``VIRTUAL_ENV`` so the venv layout
       # downstream jobs rely on is preserved.
       if: steps.cache-venv.outputs.cache-hit != 'true'
-      uses: astral-sh/setup-uv@20cfd1bf945f4377ade1205e4dbc17946fc9a30d # v10.0.1
+      uses: astral-sh/setup-uv@c18668ad3cf93ea998bef934396af7bb5c839dc7 # v10.2.0
       with:
         enable-cache: true
         # Pull request saves land in per-PR scopes nothing else can

.github/skills

@@ -0,0 +1 @@
+../.agents/skills

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

@@ -29,7 +29,7 @@ jobs:
       - name: Set up uv
         # ``--system`` (below) installs into the setup-python interpreter;
         # no venv is created or restored by this workflow.
-        uses: astral-sh/setup-uv@20cfd1bf945f4377ade1205e4dbc17946fc9a30d # v10.0.1
+        uses: astral-sh/setup-uv@c18668ad3cf93ea998bef934396af7bb5c839dc7 # v10.2.0
         with:
           enable-cache: true
           # Pull-request-only workflow: a save could never be shared and

.github/workflows/ci-docker.yml

@@ -12,9 +12,7 @@ on:
       - ".github/workflows/ci-docker.yml"
       - "requirements*.txt"
       - "pyproject.toml"
-      - "platformio.ini"
       - "esphome/idf_component.yml"
-      - "script/platformio_install_deps.py"
       # Core, build pipeline, toolchain, and target-platform changes can change
       # how a toolchain is set up or built, so re-run the per-toolchain compile
       # smoke test when they change.
@@ -67,7 +65,7 @@ jobs:
         with:
           python-version: "3.12"
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@37fe631027851001ddb9b187196cc803df7f5f0e # v4.3.0
+        uses: docker/setup-buildx-action@594f3bf4285d9ea8dc53c9a0c9c4092420091003 # v4.4.0
 
       - name: Determine tag and whether to push
         id: tag
@@ -119,16 +117,22 @@ jobs:
       # pushed image) keeps it working for fork PRs, which never push to ghcr.io.
       - name: Export image for compile-test
         if: matrix.os == 'ubuntu-24.04' && matrix.build_type == 'docker'
-        run: docker save "ghcr.io/esphome/esphome-amd64:${{ steps.tag.outputs.tag }}" | gzip > compile-test-image.tar.gz
+        # zstd over gzip: docker save is on the critical path for every
+        # compile-test job, and zstd -T0 is multithreaded (export 50s -> 9s).
+        # docker load auto-detects the format; its time is layer extraction,
+        # not decompression, so it is unchanged. shell: bash adds pipefail so
+        # a failed docker save cannot upload a truncated artifact.
+        shell: bash
+        run: docker save "ghcr.io/esphome/esphome-amd64:${{ steps.tag.outputs.tag }}" | zstd -T0 -3 > compile-test-image.tar.zst
 
       - name: Upload compile-test image artifact
         if: matrix.os == 'ubuntu-24.04' && matrix.build_type == 'docker'
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
-          # The tar is already gzipped, so upload it as-is. archive: false skips
-          # the redundant zip and makes the file name the artifact name (the
-          # `name` input is ignored in that mode).
-          path: compile-test-image.tar.gz
+          # The tar is already compressed, so upload it as-is. archive: false
+          # skips the redundant zip and makes the file name the artifact name
+          # (the `name` input is ignored in that mode).
+          path: compile-test-image.tar.zst
           retention-days: 1
           archive: false
 
@@ -153,7 +157,7 @@ jobs:
         with:
           python-version: "3.12"
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@37fe631027851001ddb9b187196cc803df7f5f0e # v4.3.0
+        uses: docker/setup-buildx-action@594f3bf4285d9ea8dc53c9a0c9c4092420091003 # v4.4.0
 
       - name: Log in to the GitHub container registry
         uses: docker/login-action@dbcb813823bdd20940b903addbd779551569679f # v4.6.0
@@ -182,8 +186,6 @@ jobs:
       contents: read  # actions/checkout to load the test configs
     strategy:
       fail-fast: false
-      # Modest cap so this smoke test leaves room on the shared runner pool.
-      max-parallel: 8
       matrix:
         # One entry per distinct toolchain. ESP32 variants (c3/c6/s2/s3/p4)
         # share a toolchain bundle, so esp32 is exercised on the base variant
@@ -208,9 +210,9 @@ jobs:
       - name: Download image artifact
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
-          name: compile-test-image.tar.gz
+          name: compile-test-image.tar.zst
       - name: Load image
-        run: docker load --input compile-test-image.tar.gz
+        run: docker load --input compile-test-image.tar.zst
       - name: Compile ${{ matrix.id }}
         run: |
           docker run --rm \

.github/workflows/ci.yml

@@ -49,7 +49,7 @@ jobs:
         # detects the activated venv via ``VIRTUAL_ENV`` so downstream jobs
         # that ``. venv/bin/activate`` see an identical layout.
         if: steps.cache-venv.outputs.cache-hit != 'true'
-        uses: astral-sh/setup-uv@20cfd1bf945f4377ade1205e4dbc17946fc9a30d # v10.0.1
+        uses: astral-sh/setup-uv@c18668ad3cf93ea998bef934396af7bb5c839dc7 # v10.2.0
         with:
           enable-cache: true
           # Pull request saves land in per-PR scopes nothing else can
@@ -92,6 +92,7 @@ jobs:
     outputs:
       core-ci: ${{ steps.determine.outputs.core-ci }}
       integration-tests: ${{ steps.determine.outputs.integration-tests }}
+      integration-run-all: ${{ steps.determine.outputs.integration-run-all }}
       integration-test-buckets: ${{ steps.determine.outputs.integration-test-buckets }}
       clang-tidy: ${{ steps.determine.outputs.clang-tidy }}
       clang-tidy-mode: ${{ steps.determine.outputs.clang-tidy-mode }}
@@ -112,6 +113,12 @@ jobs:
       component-test-batches: ${{ steps.determine.outputs.component-test-batches }}
       validate-only-components: ${{ steps.determine.outputs.validate-only-components }}
       benchmarks: ${{ steps.determine.outputs.benchmarks }}
+      # "true" when this run is a pull request into one of the release
+      # branches. Those pull requests are batches of changes already tested on
+      # their original dev pull requests, so several jobs below trade coverage
+      # for turnaround time on them. Matched exactly, not by prefix, so an
+      # ordinary branch named e.g. "release-notes" is not caught by it.
+      release-pr: ${{ github.base_ref == 'beta' || github.base_ref == 'release' }}
     steps:
       - name: Check out code from GitHub
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -146,6 +153,9 @@ jobs:
           # Extract individual fields
           echo "core-ci=$(echo "$output" | jq -r '.core_ci')" >> $GITHUB_OUTPUT
           echo "integration-tests=$(echo "$output" | jq -r '.integration_tests')" >> $GITHUB_OUTPUT
+          # A missing key must fail here, not silently disable the junit upload
+          run_all=$(echo "$output" | jq -r 'if has("integration_run_all") then .integration_run_all else error("integration_run_all missing") end')
+          echo "integration-run-all=${run_all}" >> $GITHUB_OUTPUT
           echo "integration-test-buckets=$(echo "$output" | jq -c '.integration_test_buckets')" >> $GITHUB_OUTPUT
           echo "clang-tidy=$(echo "$output" | jq -r '.clang_tidy')" >> $GITHUB_OUTPUT
           echo "clang-tidy-mode=$(echo "$output" | jq -r '.clang_tidy_mode')" >> $GITHUB_OUTPUT
@@ -230,15 +240,24 @@ jobs:
     runs-on: ubuntu-latest
     needs:
       - determine-jobs
-    if: github.event_name == 'pull_request' && !startsWith(github.base_ref, 'beta') && !startsWith(github.base_ref, 'release') && needs.determine-jobs.outputs.core-ci == 'true'
+    if: github.event_name == 'pull_request' && needs.determine-jobs.outputs.release-pr == 'false' && needs.determine-jobs.outputs.core-ci == 'true'
     steps:
       - name: Check out code from GitHub
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - name: Read prek version from requirements_test.txt
+        id: prek
+        # requirements_test.txt is the only place the version is pinned, so a
+        # Dependabot bump there is picked up here without a second edit.
+        run: |
+          if ! version=$(sed -nE 's/^prek==([^[:space:]#]+).*/\1/p' requirements_test.txt) || [ -z "$version" ]; then
+            echo "::error::No prek== pin found in requirements_test.txt."
+            exit 1
+          fi
+          echo "version=$version" >> "$GITHUB_OUTPUT"
       - name: Run prek
         uses: j178/prek-action@4e14d07f9231acabce116ccfca13b13dd9755ece # v3.0.0
         with:
-          # Keep in sync with requirements_test.txt.
-          prek-version: "0.4.11"
+          prek-version: ${{ steps.prek.outputs.version }}
           # This job only runs on pull requests, so nothing ever populates
           # the cache on dev. Every run would miss and then write a per-pull
           # request copy, which is what the old seed-cache job existed to
@@ -302,7 +321,7 @@ jobs:
           . venv/bin/activate
           pytest -vv --cov-report=xml --tb=native --durations=30 -n auto tests --ignore=tests/integration/
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@fb8b3582c8e4def4969c97caa2f19720cb33a72f # v7.0.0
+        uses: codecov/codecov-action@303a32d7a59b442fa8d48b6a1cc6825c09c847a5 # v7.1.1
       - name: Save Python virtual environment cache
         if: github.ref == 'refs/heads/dev'
         uses: actions/cache/save@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
@@ -331,7 +350,7 @@ jobs:
       - name: Check out code from GitHub
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - name: Report empty upload to Codecov
-        uses: codecov/codecov-action@fb8b3582c8e4def4969c97caa2f19720cb33a72f # v7.0.0
+        uses: codecov/codecov-action@303a32d7a59b442fa8d48b6a1cc6825c09c847a5 # v7.1.1
         with:
           run_command: empty-upload
           force: true
@@ -349,14 +368,24 @@ jobs:
       fail-fast: false
       matrix:
         bucket: ${{ fromJson(needs.determine-jobs.outputs.integration-test-buckets) }}
+    env:
+      # What the cache steps persist; libdeps is excluded (keyed per xdist
+      # worker and env, it never crosses runs).
+      INTEGRATION_PIO_CACHE_PATH: |
+        ~/.esphome-integration-tests/platformio/platforms
+        ~/.esphome-integration-tests/platformio/packages
+        ~/.esphome-integration-tests/platformio/appstate.json
+        ~/.esphome-integration-tests/platformio/.cache
+        ~/.esphome-integration-tests/platformio/.esphome.pio.stamp.json
     steps:
       - name: Check out code from GitHub
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - 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.
+        # path. Packages and version must match seed-apt-cache exactly.
+        # libsdl2-dev is needed by the headless display tests, which capture
+        # screenshots.
         timeout-minutes: 10
         uses: awalsh128/cache-apt-pkgs-action@553a35bb8ebd9fcabcb1c9451aa4c98e1b4ca8a9 # v1.6.3
         with:
@@ -367,6 +396,14 @@ jobs:
         uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
         with:
           python-version: "3.13"
+      - name: Restore integration PlatformIO cache
+        # Native platform + toolchain installed by shared_platformio_cache in
+        # tests/integration/conftest.py; a miss self-heals, so no restore-keys.
+        id: pio-cache
+        uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+        with:
+          path: ${{ env.INTEGRATION_PIO_CACHE_PATH }}
+          key: integration-pio-v1-${{ runner.os }}-py${{ steps.python.outputs.python-version }}-${{ hashFiles('requirements.txt', 'tests/integration/fixtures/cache_init.yaml', 'esphome/components/host/__init__.py') }}
       - name: Restore Python virtual environment
         id: cache-venv
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
@@ -376,7 +413,7 @@ jobs:
       - name: Set up uv
         # Only needed on cache miss to populate the venv.
         if: steps.cache-venv.outputs.cache-hit != 'true'
-        uses: astral-sh/setup-uv@20cfd1bf945f4377ade1205e4dbc17946fc9a30d # v10.0.1
+        uses: astral-sh/setup-uv@c18668ad3cf93ea998bef934396af7bb5c839dc7 # v10.2.0
         with:
           enable-cache: true
           # Pull request saves land in per-PR scopes nothing else can
@@ -404,12 +441,46 @@ jobs:
         run: |
           . venv/bin/activate
           mapfile -t test_files < <(echo "$BUCKET_TESTS" | jq -r '.[]')
+          if [ "${#test_files[@]}" -eq 0 ]; then
+            echo "::error::Empty integration test bucket; pytest would collect the whole tree"
+            exit 1
+          fi
           echo "Bucket ${{ matrix.bucket.name }}: running ${#test_files[@]} integration tests"
-          pytest -vv --no-cov --tb=native --durations=30 -n auto "${test_files[@]}"
+          pytest -vv --no-cov --tb=native --durations=30 -n auto --dist worksteal \
+            --junitxml=junit-integration.xml "${test_files[@]}"
+      - name: Upload test artifacts
+        # Tests that compare rendered output write the image they actually got here, so a
+        # failure can be looked at without reproducing the whole build locally.
+        if: failure()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: integration-test-artifacts-${{ matrix.bucket.name }}
+          path: test_artifacts/
+          if-no-files-found: ignore
+          retention-days: 7
+      - name: Upload junit timings
+        # Consumed by sync-integration-durations.yml through
+        # script/update_integration_test_durations.py; only full matrix dev
+        # runs produce usable data.
+        if: github.ref == 'refs/heads/dev' && needs.determine-jobs.outputs.integration-run-all == 'true'
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: junit-integration-${{ strategy.job-index }}
+          path: junit-integration.xml
+          if-no-files-found: error
+          # A full cron period of margin for the weekly refresh
+          retention-days: 14
       - name: Print ccache statistics
         # esphome stores the PlatformIO ccache under the machine-global cache
         # dir (see _ccache_env() in esphome/platformio/toolchain.py).
         run: CCACHE_DIR="$HOME/.cache/esphome/platformio-ccache" ccache -s
+      - name: Save integration PlatformIO cache
+        # Bucket 0 only; the others would race the same immutable key.
+        if: success() && (github.ref == 'refs/heads/dev' || contains(github.event.pull_request.labels.*.name, 'ci-cache-write')) && strategy.job-index == 0 && steps.pio-cache.outputs.cache-hit != 'true'
+        uses: actions/cache/save@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+        with:
+          path: ${{ env.INTEGRATION_PIO_CACHE_PATH }}
+          key: ${{ steps.pio-cache.outputs.cache-primary-key }}
 
   import-time:
     name: Check import esphome.__main__ time
@@ -449,10 +520,21 @@ jobs:
     if: >-
       github.repository == 'esphome/esphome' && (
         (github.event_name == 'push' && github.ref_name == 'dev') ||
-        (github.event_name == 'pull_request' && needs.determine-jobs.outputs.benchmarks == 'true')
+        (
+          github.event_name == 'pull_request' &&
+          needs.determine-jobs.outputs.release-pr == 'false' &&
+          needs.determine-jobs.outputs.benchmarks == 'true'
+        )
       )
     # CodSpeed benchmarks require a CodSpeed account linked to the repository to run
     # (https://codspeed.io) -- disabled on forks that aren't esphome/esphome itself.
+    #
+    # Pull requests into beta and release are skipped as well. CodSpeed compares a
+    # pull request against the newest commit of its base branch that has a benchmark
+    # run of its own, and only dev is benchmarked. A release pull request therefore
+    # falls back to dev's latest run, so every speed-up merged into dev since the
+    # release branched is reported as a regression in the release. The changes there
+    # have already been benchmarked on their original dev pull requests.
     steps:
       - name: Check out code from GitHub
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -519,7 +601,7 @@ jobs:
             apt-get install -y libc6-dbg
 
       - name: Run CodSpeed benchmarks
-        uses: CodSpeedHQ/action@4296e51e7041e24dadb86d1d6e8b9320d223dbe8 # v5.0.3
+        uses: CodSpeedHQ/action@373d6868929f444bc08d901fd0eb0ad52a8875ea # v5.2.1
         with:
           run: |
             . venv/bin/activate
@@ -632,6 +714,12 @@ jobs:
         with:
           framework: arduino
 
+      - name: Cache clang-tidy idedata
+        if: matrix.cache_idf
+        uses: ./.github/actions/cache-clang-tidy-idedata
+        with:
+          environment: esp32-arduino-tidy
+
       - name: Cache nRF Connect SDK install
         if: matrix.cache_sdk_nrf
         uses: ./.github/actions/cache-sdk-nrf
@@ -681,6 +769,10 @@ jobs:
           # Also cache libdeps, store them in a ~/.platformio subfolder
           PLATFORMIO_LIBDEPS_DIR: ~/.platformio/libdeps
 
+      - name: Prune ESP-IDF install before cache save
+        if: matrix.cache_idf && (github.ref == 'refs/heads/dev' || contains(github.event.pull_request.labels.*.name, 'ci-cache-write'))
+        uses: ./.github/actions/prune-esp-idf
+
       - name: Suggested changes
         run: script/ci-suggest-changes ${{ matrix.ignore_errors && '|| true' || '' }}
         # yamllint disable-line rule:line-length
@@ -713,6 +805,11 @@ jobs:
       - name: Cache ESP-IDF install
         uses: ./.github/actions/cache-esp-idf
 
+      - name: Cache clang-tidy idedata
+        uses: ./.github/actions/cache-clang-tidy-idedata
+        with:
+          environment: esp32-idf-tidy
+
       - name: Register problem matchers
         run: |
           echo "::add-matcher::.github/workflows/matchers/gcc.json"
@@ -747,6 +844,10 @@ jobs:
           # Also cache libdeps, store them in a ~/.platformio subfolder
           PLATFORMIO_LIBDEPS_DIR: ~/.platformio/libdeps
 
+      - name: Prune ESP-IDF install before cache save
+        if: (github.ref == 'refs/heads/dev' || contains(github.event.pull_request.labels.*.name, 'ci-cache-write'))
+        uses: ./.github/actions/prune-esp-idf
+
       - name: Suggested changes
         run: script/ci-suggest-changes
         if: always()
@@ -792,6 +893,11 @@ jobs:
       - name: Cache ESP-IDF install
         uses: ./.github/actions/cache-esp-idf
 
+      - name: Cache clang-tidy idedata
+        uses: ./.github/actions/cache-clang-tidy-idedata
+        with:
+          environment: esp32-idf-tidy
+
       - name: Register problem matchers
         run: |
           echo "::add-matcher::.github/workflows/matchers/gcc.json"
@@ -826,6 +932,10 @@ jobs:
           # Also cache libdeps, store them in a ~/.platformio subfolder
           PLATFORMIO_LIBDEPS_DIR: ~/.platformio/libdeps
 
+      - name: Prune ESP-IDF install before cache save
+        if: (github.ref == 'refs/heads/dev' || contains(github.event.pull_request.labels.*.name, 'ci-cache-write'))
+        uses: ./.github/actions/prune-esp-idf
+
       - name: Suggested changes
         run: script/ci-suggest-changes
         if: always()
@@ -849,16 +959,19 @@ jobs:
             name: Run script/clang-tidy for ESP32 S3
             # yamllint disable-line rule:line-length
             options: --environment esp32s3-idf-tidy --grep SOC_TEMP_SENSOR_SUPPORTED --grep USE_ESP32_VARIANT_ESP32S3 --grep USE_LOGGER_USB_CDC
+            tidy_environment: esp32s3-idf-tidy
           - id: clang-tidy
             name: Run script/clang-tidy for ESP32 P4
             # P4 has no native Wi-Fi/BLE; those run over the hosted co-processor,
             # so their code paths differ -- lint them under the P4 build too.
             # yamllint disable-line rule:line-length
             options: --environment esp32p4-idf-tidy --grep USE_ESP32_VARIANT_ESP32P4 --grep USE_ESP32_HOSTED --grep USE_WIFI --grep USE_BLE
+            tidy_environment: esp32p4-idf-tidy
           - id: clang-tidy
             name: Run script/clang-tidy for ESP32 C6
             # yamllint disable-line rule:line-length
             options: --environment esp32c6-idf-tidy --grep SOC_LP_I2C_SUPPORTED --grep USE_ESP32_VARIANT_ESP32C6 --grep USE_OPENTHREAD --grep USE_ZIGBEE
+            tidy_environment: esp32c6-idf-tidy
 
     steps:
       - name: Check out code from GitHub
@@ -876,6 +989,11 @@ jobs:
       - name: Cache ESP-IDF install
         uses: ./.github/actions/cache-esp-idf
 
+      - name: Cache clang-tidy idedata
+        uses: ./.github/actions/cache-clang-tidy-idedata
+        with:
+          environment: ${{ matrix.tidy_environment }}
+
       - name: Register problem matchers
         run: |
           echo "::add-matcher::.github/workflows/matchers/gcc.json"
@@ -909,6 +1027,10 @@ jobs:
             script/clang-tidy --fix --changed ${{ matrix.options }}
           fi
 
+      - name: Prune ESP-IDF install before cache save
+        if: (github.ref == 'refs/heads/dev' || contains(github.event.pull_request.labels.*.name, 'ci-cache-write'))
+        uses: ./.github/actions/prune-esp-idf
+
       - name: Suggested changes
         run: script/ci-suggest-changes
         if: always()
@@ -929,7 +1051,6 @@ jobs:
       ESPHOME_SDK_NRF_PREFIX: ~/.esphome-sdk-nrf
     strategy:
       fail-fast: false
-      max-parallel: ${{ (startsWith(github.base_ref, 'beta') || startsWith(github.base_ref, 'release')) && 32 || 16 }}
       matrix:
         batch: ${{ fromJson(needs.determine-jobs.outputs.component-test-batches) }}
     steps:
@@ -1016,7 +1137,7 @@ jobs:
           # - This catches pin conflicts and other issues in directly changed code
           # - Grouped tests use --testing-mode to allow config merging (disables some checks)
           # - Dependencies are safe to group since they weren't modified in this PR
-          if [[ "${{ github.base_ref }}" == beta* ]] || [[ "${{ github.base_ref }}" == release* ]]; then
+          if [[ "${{ needs.determine-jobs.outputs.release-pr }}" == "true" ]]; then
             directly_changed_csv=""
             echo "Testing components: $components_csv"
             echo "Target branch: ${{ github.base_ref }} - grouping all components"
@@ -1153,7 +1274,7 @@ jobs:
         # install step (order-of-magnitude faster on cold boots,
         # with its own wheel cache). actions/setup-python still
         # provides the interpreter.
-        uses: astral-sh/setup-uv@20cfd1bf945f4377ade1205e4dbc17946fc9a30d # v10.0.1
+        uses: astral-sh/setup-uv@c18668ad3cf93ea998bef934396af7bb5c839dc7 # v10.2.0
         with:
           enable-cache: true
           # Pull request saves land in per-PR scopes nothing else can

.github/workflows/codeql.yml

@@ -56,7 +56,7 @@ jobs:
 
       # Initializes the CodeQL tools for scanning.
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@ff2f1c621b7f889edc0d3c761ac2e6a3f8cdb0dd # v4.37.7
+        uses: github/codeql-action/init@1c5b675653bb5c22dbe9b12b556ec555138e09fd # v4.38.1
         with:
           languages: ${{ matrix.language }}
           build-mode: ${{ matrix.build-mode }}
@@ -84,6 +84,6 @@ jobs:
           exit 1
 
       - name: Perform CodeQL Analysis
-        uses: github/codeql-action/analyze@ff2f1c621b7f889edc0d3c761ac2e6a3f8cdb0dd # v4.37.7
+        uses: github/codeql-action/analyze@1c5b675653bb5c22dbe9b12b556ec555138e09fd # v4.38.1
         with:
           category: "/language:${{matrix.language}}"

.github/workflows/lock.yml

@@ -14,4 +14,4 @@ jobs:
     permissions:
       issues: write         # issues.lock on closed issues
       pull-requests: write  # issues.lock on closed pull requests
-    uses: esphome/workflows/.github/workflows/lock.yml@0fdd5e311b7e744069166696072a1a9cbc5fbeb6  # 2026.8.1
+    uses: esphome/workflows/.github/workflows/lock.yml@cc3e76de337dc59bc1cba8da58d963cd23b873f1  # 2026.9.0

.github/workflows/release.yml

@@ -123,7 +123,7 @@ jobs:
           python-version: "3.12"
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@37fe631027851001ddb9b187196cc803df7f5f0e # v4.3.0
+        uses: docker/setup-buildx-action@594f3bf4285d9ea8dc53c9a0c9c4092420091003 # v4.4.0
 
       - name: Log in to docker hub
         uses: docker/login-action@dbcb813823bdd20940b903addbd779551569679f # v4.6.0
@@ -202,7 +202,7 @@ jobs:
           merge-multiple: true
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@37fe631027851001ddb9b187196cc803df7f5f0e # v4.3.0
+        uses: docker/setup-buildx-action@594f3bf4285d9ea8dc53c9a0c9c4092420091003 # v4.4.0
 
       - name: Log in to docker hub
         if: matrix.registry == 'dockerhub'

.github/workflows/stale.yml

@@ -16,7 +16,7 @@ jobs:
     # No GITHUB_TOKEN permissions: the reusable workflow mints an ESPHome
     # GitHub App token so the labels, comments and closures come from
     # esphome[bot] instead of github-actions[bot].
-    uses: esphome/workflows/.github/workflows/stale.yml@a1c1485ab46ef41a84a6a9d8abd7fa4b7628fd70  # main
+    uses: esphome/workflows/.github/workflows/stale.yml@cc3e76de337dc59bc1cba8da58d963cd23b873f1  # main
     secrets:
       ESPHOME_GITHUB_APP_PRIVATE_KEY: ${{ secrets.ESPHOME_GITHUB_APP_PRIVATE_KEY }}
     with:
@@ -33,7 +33,7 @@ jobs:
         and will be closed if no further activity occurs within 7 days.
 
         If you are the author of this PR, please leave a comment if you want
-        to keep it open. Also, please rebase your PR onto the latest dev
+        to keep it open. Also, please merge the latest dev branch into your
         branch to ensure that it's up to date with the latest changes.
 
         Thank you for your contribution!

.github/workflows/sync-dependency-versions.yml

@@ -0,0 +1,94 @@
+# Keeps pre-commit hook revs in sync with the requirements files.
+#
+# Dependabot only bumps the pins in requirements*.txt. Some of those tools
+# are pinned again as hook revs in .pre-commit-config.yaml. This workflow
+# runs script/sync_dependency_versions.py against the pull request branch
+# and pushes a commit with the revs updated.
+
+name: Sync dependency versions
+
+on:
+  # pull_request_target rather than pull_request so the App secret is
+  # available on Dependabot pull requests (pull_request runs opened by
+  # Dependabot only see Dependabot secrets). The job below only touches
+  # branches in this repository and only ever executes the script from the
+  # base branch checkout, so fork code never runs with the token.
+  pull_request_target:
+    types: [opened, synchronize, reopened]
+    paths:
+      - requirements_dev.txt
+      - requirements_test.txt
+      - .pre-commit-config.yaml
+      - script/sync_dependency_versions.py
+
+# The push to the pull request branch uses the App token minted below, so
+# the workflow's GITHUB_TOKEN does not need any scopes.
+permissions: {}
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+jobs:
+  sync:
+    name: Sync pinned versions
+    runs-on: ubuntu-latest
+    # Same-repository branches only: a push to a fork is not possible with
+    # this token, and it keeps untrusted heads out of a privileged job.
+    if: >-
+      github.repository == 'esphome/esphome'
+      && github.event.pull_request.head.repo.full_name == github.repository
+    steps:
+      - name: Generate a token
+        id: generate-token
+        uses: actions/create-github-app-token@bcd2ba49218906704ab6c1aa796996da409d3eb1 # v3.2.0
+        with:
+          client-id: ${{ vars.ESPHOME_GITHUB_APP_CLIENT_ID }}
+          private-key: ${{ secrets.ESPHOME_GITHUB_APP_PRIVATE_KEY }}
+          # A push made with the workflow's own GITHUB_TOKEN would not start
+          # CI on the new commit; a push with the App token does.
+          permission-contents: write  # git push of the sync commit to the pull request branch
+
+      - name: Check out base branch
+        # Provides the script that runs below. Deliberately the base branch
+        # so the pull request cannot change what executes here.
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          ref: ${{ github.event.pull_request.base.sha }}
+          persist-credentials: false
+
+      - name: Check out pull request branch
+        # No allow-unsafe-pr-checkout here on purpose: checkout v7 only
+        # refuses heads that live in a different repository, and the job
+        # condition above already limits runs to same-repository branches.
+        # Leaving it off keeps that refusal as a backstop for fork heads.
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          ref: ${{ github.event.pull_request.head.ref }}
+          path: pull-request
+          token: ${{ steps.generate-token.outputs.token }}
+
+      - name: Set up Python
+        uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+        with:
+          python-version: "3.12"
+
+      - name: Install yamlrocks
+        # The script edits YAML through yamlrocks. Take the pin from the
+        # base branch requirements so this workflow has no copy of its own.
+        run: pip install "$(grep -E '^yamlrocks==' requirements_test.txt | cut -d'#' -f1)"
+
+      - name: Sync pinned versions
+        run: python script/sync_dependency_versions.py --root pull-request
+
+      - name: Push changes
+        working-directory: pull-request
+        run: |
+          if git diff --quiet; then
+            echo "All pinned versions already match the requirements files."
+            exit 0
+          fi
+          git config user.name "esphome[bot]"
+          git config user.email "115708604+esphome[bot]@users.noreply.github.com"
+          git commit -am "Sync pinned tool versions with requirements files"
+          git push

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

@@ -47,7 +47,7 @@ jobs:
         # setup-python interpreter so subsequent ``prek`` /
         # ``script/run-in-env.py`` steps find the deps without a
         # ``uv run`` prefix.
-        uses: astral-sh/setup-uv@20cfd1bf945f4377ade1205e4dbc17946fc9a30d # v10.0.1
+        uses: astral-sh/setup-uv@c18668ad3cf93ea998bef934396af7bb5c839dc7 # v10.2.0
         with:
           enable-cache: true
           # Pin uv version so the action does not have to fetch the

.github/workflows/sync-integration-durations.yml

@@ -0,0 +1,98 @@
+---
+name: Refresh integration test durations
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: "45 5 * * 1"
+
+# Repo writes (branch push, PR open) happen via the App token minted below,
+# so the workflow's GITHUB_TOKEN does not need any write scopes.
+permissions:
+  contents: read
+  actions: read  # gh api / gh run download for the CI junit artifacts
+
+jobs:
+  sync:
+    name: Refresh integration test durations
+    runs-on: ubuntu-latest
+    if: github.repository == 'esphome/esphome'
+    steps:
+      - name: Generate a token
+        id: generate-token
+        uses: actions/create-github-app-token@bcd2ba49218906704ab6c1aa796996da409d3eb1 # v3.2.0
+        with:
+          client-id: ${{ vars.ESPHOME_GITHUB_APP_CLIENT_ID }}
+          private-key: ${{ secrets.ESPHOME_GITHUB_APP_PRIVATE_KEY }}
+          permission-contents: write       # push the sync branch
+          permission-pull-requests: write  # open or refresh the sync PR
+
+      - name: Checkout
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+      - name: Setup Python
+        uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+        with:
+          python-version: "3.13"
+
+      - name: Refresh from the newest usable dev run
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          # Only full matrix dev runs upload junit-integration-* artifacts
+          # (see the integration-tests job); the merge script re-checks
+          # coverage regardless.
+          # Newest-first candidates via their bucket-0 artifact. Fork PRs run
+          # their own ci.yml, so name and branch are spoofable; require
+          # same-repo. Assignment failures trip set -e and fail loudly.
+          candidates=$(
+            gh api "repos/${GITHUB_REPOSITORY}/actions/artifacts?name=junit-integration-0&per_page=100" \
+              --jq '.artifacts[] | select(.expired | not) | .workflow_run
+                    | select(.head_branch == "dev" and .head_repository_id != null
+                             and .head_repository_id == .repository_id)
+                    | .id'
+          )
+          # Green runs first, then the rest newest first; a run missing a
+          # bucket fails the coverage check and the next one is tried
+          green=""
+          rest=""
+          for id in ${candidates}; do
+            conclusion=$(gh api "repos/${GITHUB_REPOSITORY}/actions/runs/${id}" --jq '.conclusion // ""')
+            if [ "${conclusion}" = "success" ]; then
+              green="${green} ${id}"
+            elif [ -n "${conclusion}" ]; then
+              rest="${rest} ${id}"
+            fi
+          done
+          # helpers.py imports colorama; the script needs nothing else
+          pip install colorama
+          for id in ${green} ${rest}; do
+            rm -rf /tmp/junit
+            if ! gh run download "${id}" --repo "${GITHUB_REPOSITORY}" -p "junit-integration-*" -D /tmp/junit; then
+              echo "::warning::Could not download artifacts for run ${id}; trying the next"
+              continue
+            fi
+            status=0
+            python script/update_integration_test_durations.py /tmp/junit || status=$?
+            if [ "${status}" -eq 0 ]; then
+              echo "Refreshed from run ${id}"
+              exit 0
+            fi
+            # Only EXIT_LOW_COVERAGE (3) from the script advances to the next run
+            [ "${status}" -eq 3 ] || exit 1
+            echo "::warning::Run ${id} covers too few test files; trying the next"
+          done
+          echo "::error::No dev CI run with usable junit artifacts in range; the feed is starved"
+          exit 1
+
+      - name: Commit changes
+        uses: peter-evans/create-pull-request@5f6978faf089d4d20b00c7766989d076bb2fc7f1 # v8.1.1
+        with:
+          commit-message: "[ci] Refresh integration test durations"
+          committer: esphome[bot] <115708604+esphome[bot]@users.noreply.github.com>
+          author: esphome[bot] <115708604+esphome[bot]@users.noreply.github.com>
+          branch: sync/integration-durations
+          delete-branch: true
+          title: "[ci] Refresh integration test durations"
+          body-path: .github/PULL_REQUEST_TEMPLATE.md
+          token: ${{ steps.generate-token.outputs.token }}

.gitignore

@@ -137,6 +137,8 @@ config/
 !tests/component_tests/**/config/
 tests/build/
 tests/.esphome/
+# Output kept by failing tests for inspection; uploaded by CI
+test_artifacts/
 /.temp-clang-tidy.cpp
 /.temp/
 .pio/

.pre-commit-config.yaml

@@ -1,7 +1,6 @@
 ---
 # See https://pre-commit.com for more information
 # See https://pre-commit.com/hooks.html for more hooks
-
 ci:
   autoupdate_commit_msg: 'pre-commit: autoupdate'
   autoupdate_schedule: off  # Disabled until ruff versions are synced between deps and pre-commit
@@ -11,7 +10,7 @@ ci:
 repos:
   - repo: https://github.com/astral-sh/ruff-pre-commit
     # Ruff version.
-    rev: v0.16.3
+    rev: v0.16.8
     hooks:
       # Run the linter.
       - id: ruff
@@ -42,7 +41,7 @@ repos:
       - id: pyupgrade
         args: [--py312-plus]
   - repo: https://github.com/adrienverge/yamllint.git
-    rev: v1.37.1
+    rev: v1.38.0
     hooks:
       - id: yamllint
         exclude: ^(\.clang-format|\.clang-tidy)$

AGENTS.md

@@ -44,6 +44,16 @@ This document provides essential context for AI models interacting with this pro
 
 ## 4. Coding Conventions & Style Guide
 
+**Read the developer documentation before writing a component.** https://developers.esphome.io covers the
+component lifecycle, the main loop, and the reasoning behind the rules below in far more depth than this
+file does, and it is the authority when they disagree. The most useful starting points:
+
+*   https://developers.esphome.io/architecture/components/ - component lifecycle, `setup()`, `loop()`,
+    setup priorities, and how a component is registered.
+*   https://developers.esphome.io/architecture/components/advanced/ - choosing between `loop()`,
+    `set_interval`, `set_timeout` and `defer`; waking the loop from another thread; the RAM cost of each.
+*   https://developers.esphome.io/contributing/code/ - contribution rules, public API and breaking changes.
+
 *   **Formatting:**
     *   **Python:** Uses `ruff` and `flake8` for linting and formatting. Configuration is in `pyproject.toml`.
     *   **C++:** Uses `clang-format` for formatting. Configuration is in `.clang-format`.
@@ -142,6 +152,47 @@ This document provides essential context for AI models interacting with this pro
     *   **Indentation:** Use spaces (two per indentation level), not tabs
     *   **Type aliases:** Prefer `using type_t = int;` over `typedef int type_t;`
     *   **Line length:** Wrap lines at no more than 120 characters
+    *   **Timing in `loop()`:** Never call `millis()` in a `loop()` body. The current tick's timestamp is
+        already cached - use `App.get_loop_component_start_time()` (from `esphome/core/application.h`).
+        Only reach for `millis()` when you genuinely need sub-tick resolution inside a long operation.
+    *   **The main loop runs every 16 ms.** A rate-limit gate shorter than that does nothing: the check
+        passes on essentially every pass of the loop, so it costs a comparison and buys nothing. Pick an
+        interval comfortably coarser than 16 ms, or drop the gate entirely and accept running every loop.
+        ```cpp
+        // Bad - a 10ms gate against a 16ms loop never holds anything back
+        static constexpr uint32_t POLL_INTERVAL_MS = 10;
+        const uint32_t now = millis();
+        if (now - this->last_poll_ < POLL_INTERVAL_MS)
+          return;
+        this->last_poll_ = now;
+        ```
+        ```cpp
+        // Good - an interval that actually rate limits, off the cached timestamp
+        static constexpr uint32_t POLL_INTERVAL_MS = 100;
+        const uint32_t now = App.get_loop_component_start_time();
+        if (now - this->last_poll_ < POLL_INTERVAL_MS)
+          return;
+        this->last_poll_ = now;
+        ```
+        Pick the primitive by cadence: under 250 ms use a gated `loop()`; 500 ms and above use
+        `set_interval`. Full reasoning, including why `set_interval` costs more below 500 ms:
+        https://developers.esphome.io/architecture/components/advanced/#quick-rule-of-thumb
+    *   **Don't override a default with the same value:** if a base class method already returns what you
+        want, do not override it. `Component::get_setup_priority()` returns `setup_priority::DATA`, so a
+        component that wants `DATA` should simply leave it alone.
+        ```cpp
+        // Bad - this is exactly what the base class already does
+        float get_setup_priority() const override { return setup_priority::DATA; }
+        ```
+    *   **Logging string literals:** wrap literals passed as `%s` arguments in `LOG_STR_LITERAL()` so they
+        can be stored in flash rather than RAM.
+        ```cpp
+        // Bad
+        ESP_LOGV(TAG, "Key %u %s", key, pressed ? "pressed" : "released");
+
+        // Good
+        ESP_LOGV(TAG, "Key %u %s", key, pressed ? LOG_STR_LITERAL("pressed") : LOG_STR_LITERAL("released"));
+        ```
     *   **Constructor parameters vs setters:** Component properties that are both **required** and **invariant**
         (never change after construction) should be constructor parameters rather than set via setter methods.
         This makes the dependency explicit and prevents use of the object in an incompletely-initialized state.
@@ -380,7 +431,31 @@ This document provides essential context for AI models interacting with this pro
           MyComponent *parent_;
         };
         ```
-        Register with `@automation.register_action("my_component.do_something", MyAction, schema, synchronous=True)`. Use `synchronous=True` for actions that run to completion inside `play()` without deferring. Use `synchronous=False` if the action may suspend/defer execution (e.g. `delay`, `wait_until`, `script.wait`) or store trigger arguments for later use.
+        Register it without writing a builder:
+        ```python
+        automation.register_simple_action(
+            "my_component.do_something", MyAction, schema, synchronous=True
+        )
+        ```
+        The constructor receives the object named by `config[CONF_ID]`. Use `register_bare_action` for a
+        no-argument constructor, `register_parented_action` for a class deriving from `Parented<T>`, and
+        the `@automation.register_action(...)` decorator only when the builder must also set fields.
+
+        Use `synchronous=True` for actions that run to completion inside `play()` without deferring. Use `synchronous=False` if the action may suspend/defer execution (e.g. `delay`, `wait_until`, `script.wait`) or store trigger arguments for later use.
+
+        **Actions that only forward templatable values to their parent need no C++ class.** Register them
+        with `register_apply_action`; do not write a `TEMPLATABLE_VALUE` class or a builder for this shape.
+        ```python
+        automation.register_apply_action(
+            "my_component.set_gains",
+            schema,
+            automation.ApplyField(CONF_KP, "set_kp", cg.float_),
+            automation.ApplyField(CONF_KI, "set_ki", cg.float_),
+        )
+        ```
+        The `ApplyField`, `ApplyCall` and `register_apply_action` docstrings in `esphome/automation.py` cover
+        the rest; `cover.control` and `cover.template.publish` are in-tree examples. `TEMPLATABLE_VALUE` with
+        `cg.templatable` stays for actions whose `play()` has real logic beyond forwarding values.
 
     *   **Conditions:**
         ```cpp
@@ -392,7 +467,21 @@ This document provides essential context for AI models interacting with this pro
           MyComponent *parent_;
         };
         ```
-        Register with `@automation.register_condition("my_component.is_active", MyCondition, schema)`.
+        Register with `automation.register_simple_condition("my_component.is_active", MyCondition, schema)`;
+        `register_bare_condition`, `register_parented_condition` and the decorator follow the action rules.
+
+        **Conditions that only test their parent need no C++ class either.** Register them with
+        `register_apply_condition`; the expression is applied to the parent, and an `ApplyCall` compares
+        against config values.
+        ```python
+        automation.register_apply_condition("my_component.is_active", schema, "is_active()")
+        automation.register_apply_condition(
+            "my_component.state_is",
+            schema,
+            automation.ApplyCall("state == {}", ((CONF_STATE, cg.bool_),)),
+        )
+        ```
+        `cover.is_open`, `rtttl.is_playing` and `component.is_idle` are in-tree examples.
 
 *   **Type Hints:** Type-hint all function signatures, including test functions and config validators (e.g. `def validate_x(config: ConfigType) -> ConfigType:`, `def test_x() -> None:`). Import `ConfigType` from `esphome.types`.
 
@@ -502,6 +591,7 @@ This document provides essential context for AI models interacting with this pro
     4.  **Lint:** Run `prek` to ensure code is compliant.
     5.  **Commit:** Commit your changes. There is no strict format for commit messages.
     6.  **Pull Request:** Submit a PR against the `dev` branch. The Pull Request title must start with a `[tag]` prefix. For component work, use the component name (e.g., `[display] Fix bug`, `[abc123] Add new component`); for changes to shared/core code that isn't tied to a single component, use `[core]` (e.g., `[core] Add validator`). Update documentation, examples, and add `CODEOWNERS` entries as needed. Pull requests should always be made using the `.github/PULL_REQUEST_TEMPLATE.md` template - fill out all sections completely without removing any parts of the template.
+    7.  **Comments:** When commenting on GitHub PRs or issues, don't tag contributors, especially bots. Avoid referring to list items (e.g. from reviews) with the form #nn - this will be interpreted by GitHub as a reference to issue or PR nn. Keep comments short and exclude irrelevant details, backstories, restatement of previous comments and anything that is already obvious to the reader.
 
 *   **Documentation Contributions:**
     *   Documentation is hosted in the separate `esphome/esphome.io` repository.
@@ -562,6 +652,36 @@ This document provides essential context for AI models interacting with this pro
            Use `cg.add_define("MAX_SERVICES", count)` to set the size from Python configuration.
            Like `std::array` but with vector-like API (`push_back()`, `size()`) and no STL reallocation code.
 
+           **Listener and child-entity registration lists are the most common case, and the most commonly
+           missed.** A `register_*()` method called once per child at code generation time has a count that
+           is known at compile time, so it should never be a `std::vector`. Use `cg.slot_counter()`: it
+           returns a function that each consumer calls once per slot it will occupy, and after every
+           `to_code` has run it emits the define with the final count. When nothing registers, no define is
+           emitted and the storage plus its registration method compile out entirely.
+           ```python
+           # hub component's __init__.py
+           _request_listener_slot = cg.slot_counter("MY_COMPONENT_LISTENER_COUNT")
+
+
+           async def register_listener(hub: MockObj, var: MockObj) -> None:
+               _request_listener_slot()
+               cg.add(hub.register_listener(var))
+           ```
+           When several instances each own a list declared at the same size (one per hub of a
+           `MULTI_CONF` component), pass the owning object as the key, `_request_listener_slot(str(hub))`;
+           the define is then the largest count any one key requested instead of the total.
+           ```cpp
+           #ifdef MY_COMPONENT_LISTENER_COUNT
+             void register_listener(MyComponentListener *listener);
+           #endif
+            protected:
+           #ifdef MY_COMPONENT_LISTENER_COUNT
+             StaticVector<MyComponentListener *, MY_COMPONENT_LISTENER_COUNT> listeners_;
+           #endif
+           ```
+           Request slots from `to_code`, not from a job that runs after `CoroPriority.FINAL` - a late
+           request raises rather than silently undercounting.
+
         3. **Runtime-known sizes:** Use `FixedVector` from `esphome/core/helpers.h` when the size is only known at runtime initialization.
            ```cpp
            // Bad - generates STL realloc code (_M_realloc_insert)
@@ -599,9 +719,27 @@ This document provides essential context for AI models interacting with this pro
            ```
            Linear search on small datasets (1-16 elements) is often faster than hashing/tree overhead, but this depends on lookup frequency and access patterns. For frequent lookups in hot code paths, the O(1) vs O(n) complexity difference may still matter even for small datasets. `std::vector` with simple structs is usually fine—it's the heavy containers (`map`, `set`, `unordered_map`) that should be avoided for small datasets unless profiling shows otherwise.
 
-        5. **Avoid `std::deque`:** It allocates in 512-byte blocks regardless of element size, guaranteeing at least 512 bytes of RAM usage immediately. This is a major source of crashes on memory-constrained devices.
+        5. **Strings set once from configuration:** Use `StringRef` (`esphome/core/string_ref.h`) rather than
+           `std::string`. Code generation passes a string literal that lives in flash for the life of the
+           program, so storing a `std::string` copies it onto the heap for nothing. `StringRef` is a
+           non-owning pointer plus length; it does not copy, and it must only ever refer to storage that
+           outlives it (a string literal, or a buffer owned elsewhere).
+           ```cpp
+           // Bad - heap copy of a literal that is already in flash
+           void set_keys(std::string keys) { this->keys_ = std::move(keys); }
+           std::string keys_;
+           ```
+           ```cpp
+           // Good - no allocation
+           void set_keys(const char *keys) { this->keys_ = StringRef(keys); }
+           StringRef keys_;
+           ```
 
-        6. **Detection:** Look for these patterns in compiler output:
+        6. **Avoid `std::deque`:** It allocates in 512-byte blocks regardless of element size, guaranteeing at least 512 bytes of RAM usage immediately. This is a major source of crashes on memory-constrained devices.
+
+        7. **Never use `new (std::nothrow)`:** On ESP-IDF exceptions are disabled, so a failed nothrow allocation aborts instead of returning `nullptr`. Use `RAMAllocator` from `esphome/core/helpers.h`; CI rejects `std::nothrow`.
+
+        8. **Detection:** Look for these patterns in compiler output:
            - Large code sections with STL symbols (vector, map, set)
            - `alloc`, `realloc`, `dealloc` in symbol names
            - `_M_realloc_insert`, `_M_default_append` (vector reallocation)
@@ -745,7 +883,7 @@ This document provides essential context for AI models interacting with this pro
         cv.rename_key(
             CONF_OLD_KEY, CONF_NEW_KEY, removed_in="2026.6.0", component="my_component"
         ),
-        cv.Schema({ ... }),
+        cv.Schema({...}),
     )
     ```
     For other deprecations, warn manually during validation:

CODEOWNERS

@@ -100,6 +100,7 @@ esphome/components/bmp581_i2c/* @danielkent-net @kahrendt
 esphome/components/bmp581_spi/* @danielkent-net @kahrendt
 esphome/components/bp1658cj/* @Cossid
 esphome/components/bp5758d/* @Cossid
+esphome/components/bridge/* @kbx81
 esphome/components/bthome_mithermometer/* @nagyrobi
 esphome/components/button/* @esphome/core
 esphome/components/bytebuffer/* @clydebarrow
@@ -111,6 +112,8 @@ esphome/components/captive_portal/* @esphome/core
 esphome/components/cc1101/* @gabest11 @lygris
 esphome/components/ccs811/* @habbie
 esphome/components/cd74hc4067/* @asoehlke
+esphome/components/cdc_acm_uart/* @kbx81
+esphome/components/cdc_acm_uart/bridge/* @kbx81
 esphome/components/ch422g/* @clydebarrow @jesterret
 esphome/components/ch423/* @dwmw2
 esphome/components/chsc6x/* @kkosik20
@@ -131,6 +134,7 @@ esphome/components/cst816/* @clydebarrow
 esphome/components/cst9220/* @clydebarrow
 esphome/components/ct_clamp/* @jesserockz
 esphome/components/current_based/* @djwmarcx
+esphome/components/d01/* @ch604
 esphome/components/dac7678/* @NickB1
 esphome/components/daikin_arc/* @MagicBear
 esphome/components/daikin_brc/* @hagak
@@ -148,6 +152,7 @@ esphome/components/display_menu_base/* @numo68
 esphome/components/dlms_meter/* @latonita @PolarGoose @SimonFischer04 @Tomer27cz
 esphome/components/dps310/* @kbx81
 esphome/components/ds1307/* @badbadc0ffee
+esphome/components/ds1603l/* @JakeLC15
 esphome/components/ds2484/* @mrk-its
 esphome/components/ds248x/* @tomwellnitz
 esphome/components/dsmr/* @glmnet @PolarGoose
@@ -177,7 +182,6 @@ esphome/components/esp32_camera_web_server/* @ayufan
 esphome/components/esp32_can/* @Sympatron
 esphome/components/esp32_hosted/* @swoboda1337
 esphome/components/esp32_hosted/update/* @swoboda1337
-esphome/components/esp32_improv/* @jesserockz
 esphome/components/esp32_rmt/* @jesserockz
 esphome/components/esp32_rmt_led_strip/* @jesserockz
 esphome/components/esp8266/* @esphome/core
@@ -261,8 +265,10 @@ esphome/components/i2s_audio/* @jesserockz
 esphome/components/i2s_audio/microphone/* @jesserockz
 esphome/components/i2s_audio/speaker/* @jesserockz @kahrendt
 esphome/components/iaqcore/* @yozik04
+esphome/components/icnt86/* @danepowell
 esphome/components/ili9xxx/* @clydebarrow @nielsnl68
 esphome/components/improv_base/* @esphome/core
+esphome/components/improv_ble/* @jesserockz
 esphome/components/improv_serial/* @esphome/core
 esphome/components/ina226/* @latonita @Sergio303
 esphome/components/ina260/* @mreditor97
@@ -350,6 +356,7 @@ esphome/components/mipi_spi/* @clydebarrow
 esphome/components/mitsubishi/* @RubyBailey
 esphome/components/mitsubishi_cn105/* @crnjan
 esphome/components/mixer/speaker/* @kahrendt
+esphome/components/mk2pvrouter/* @FredM67
 esphome/components/mlx90393/* @functionpointer
 esphome/components/mlx90614/* @jesserockz
 esphome/components/mmc5603/* @benhoff
@@ -415,6 +422,7 @@ esphome/components/pn7150_i2c/* @jesserockz @kbx81
 esphome/components/pn7160/* @jesserockz @kbx81
 esphome/components/pn7160_i2c/* @jesserockz @kbx81
 esphome/components/pn7160_spi/* @jesserockz @kbx81
+esphome/components/pn71xx/* @jesserockz @kbx81
 esphome/components/power_supply/* @esphome/core
 esphome/components/preferences/* @esphome/core
 esphome/components/provisioning/* @esphome/core
@@ -422,6 +430,7 @@ esphome/components/psram/* @esphome/core
 esphome/components/pulse_meter/* @cstaahl @stevebaxter @TrentHouliston
 esphome/components/pvvx_mithermometer/* @pasiz
 esphome/components/pylontech/* @functionpointer
+esphome/components/pzem6l24/* @nuttytree
 esphome/components/qmi8658/* @clydebarrow
 esphome/components/qmp6988/* @andrewpc
 esphome/components/qr_code/* @wjtje
@@ -450,6 +459,7 @@ esphome/components/rtl87xx/* @kuba2k2
 esphome/components/rtttl/* @glmnet @ximex
 esphome/components/runtime_image/* @clydebarrow @guillempages @kahrendt
 esphome/components/runtime_stats/* @bdraco
+esphome/components/rx8025t/* @remcom
 esphome/components/rx8130/* @beormund
 esphome/components/safe_mode/* @jsuanet @kbx81 @paulmonigatti
 esphome/components/scd4x/* @martgras @sjtrny
@@ -471,11 +481,13 @@ esphome/components/sendspin/image/* @kahrendt
 esphome/components/sendspin/media_player/* @kahrendt
 esphome/components/sendspin/media_source/* @kahrendt
 esphome/components/sendspin/sensor/* @kahrendt
+esphome/components/sendspin/switch/* @kahrendt
 esphome/components/sendspin/text_sensor/* @kahrendt
 esphome/components/sensirion_common/* @martgras
 esphome/components/sensor/* @esphome/core
 esphome/components/serial_proxy/* @kbx81
 esphome/components/sfa30/* @ghsensdev
+esphome/components/sfa40/* @NoQuarrel
 esphome/components/sgp40/* @SenexCrenshaw
 esphome/components/sgp4x/* @martgras @SenexCrenshaw
 esphome/components/sha256/* @esphome/core
@@ -492,6 +504,7 @@ esphome/components/sm2335/* @Cossid
 esphome/components/sml/* @alengwenus
 esphome/components/smt100/* @piechade
 esphome/components/sn74hc165/* @jesserockz
+esphome/components/snapshot/* @clydebarrow
 esphome/components/socket/* @esphome/core
 esphome/components/sonoff_d1/* @anatoly-savchenkov
 esphome/components/sound_level/* @kahrendt
@@ -537,7 +550,9 @@ esphome/components/sx126x/* @swoboda1337
 esphome/components/sx127x/* @swoboda1337
 esphome/components/sy6970/* @linkedupbits
 esphome/components/syslog/* @clydebarrow
+esphome/components/systa_bus/* @Mat931
 esphome/components/t6615/* @tylermenezes
+esphome/components/tas2780/* @remcom
 esphome/components/tc74/* @sethgirvan
 esphome/components/tca9548a/* @andreashergert1984
 esphome/components/tca9555/* @mobrembski
@@ -550,6 +565,7 @@ esphome/components/template/datetime/* @rfdarter
 esphome/components/template/event/* @nohat
 esphome/components/template/fan/* @ssieb
 esphome/components/text/* @mauritskorse
+esphome/components/tfluna/* @candrews
 esphome/components/thermopro_ble/* @sittner
 esphome/components/thermostat/* @kbx81
 esphome/components/time/* @esphome/core
@@ -576,10 +592,12 @@ esphome/components/tuya/select/* @bearpawmaxim
 esphome/components/tuya/sensor/* @jesserockz
 esphome/components/tuya/switch/* @jesserockz
 esphome/components/tuya/text_sensor/* @dentra
+esphome/components/tuya/water_heater/* @iago-veiga
 esphome/components/uart/* @esphome/core
 esphome/components/uart/button/* @ssieb
 esphome/components/uart/event/* @eoasmxd
 esphome/components/uart/packet_transport/* @clydebarrow
+esphome/components/uart_mux/* @kbx81
 esphome/components/udp/* @clydebarrow
 esphome/components/ufire_ec/* @pvizeli
 esphome/components/ufire_ise/* @pvizeli
@@ -624,6 +642,7 @@ esphome/components/wts01/* @alepee
 esphome/components/x9c/* @EtienneMD
 esphome/components/xdb401/* @RT530
 esphome/components/xgzp68xx/* @gcormier
+esphome/components/xiaomi_body_scale/* @dckiller51
 esphome/components/xiaomi_hhccjcy10/* @fariouche
 esphome/components/xiaomi_lywsd02mmc/* @juanluss31
 esphome/components/xiaomi_lywsd03mmc/* @ahpohl

Doxyfile

@@ -48,7 +48,7 @@ PROJECT_NAME           = ESPHome
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 2026.9.0-dev
+PROJECT_NUMBER         = 2026.10.0-dev
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a

THREAT_MODEL.md

@@ -23,7 +23,8 @@ For this repository there are two trusted inputs by design:
 1. **The configuration.** Anyone who can supply or edit a YAML config is trusted
    (see below).
 2. **Authenticated peers of a running device** — clients holding the device's
-   API encryption key / password, OTA password, or web server credentials.
+   API/OTA encryption key, API password, OTA password, or web server
+   credentials.
 
 The security boundary is therefore **unauthenticated network traffic vs. those
 trusted inputs.** A bug that lets an unauthenticated attacker cross it is a
@@ -76,8 +77,8 @@ These *are* security bugs in this repo, and we want to hear about them privately
   captive portal, etc.) **without** valid credentials.
 - Authentication or encryption bypass on the device — reaching API calls, OTA
   updates, or the web server without the configured key/password.
-- Flaws that weaken the device's API encryption (Noise), OTA, or web server auth
-  below their documented guarantees.
+- Flaws that weaken the device's API or OTA encryption (Noise), OTA auth, or
+  web server auth below their documented guarantees.
 
 ## The web server is an open HTTP API by design
 
@@ -121,6 +122,54 @@ and any memory-safety or protocol bug in the server reachable without credential
 This section documents the current design and scope; it is not a judgment that the
 design is optimal or that it will not change.
 
+## OTA update encryption
+
+The `esphome` OTA platform optionally encrypts updates with the same Noise
+`NNpsk0` pattern the native API uses; one key protects the device. A device
+whose `api:` block has an encryption key, static in the YAML or provisioned at
+runtime, compiles in the transport and offers it on every OTA connection once
+it holds a key, so an uploader presenting that key gets the guarantees below
+even without an `ota: encryption:` block; only that block makes the device
+require encryption. The guarantees are: the firmware image is confidential in
+transit, the uploader is authenticated by the pre-shared key, and the plaintext
+negotiation preceding the handshake is bound into the handshake prologue, so
+stripping or tampering with it fails the first MAC. With `ota: encryption:`
+configured both ends fail closed with no override: the device refuses
+plaintext uploads, and the CLI refuses to send plaintext when a key is
+configured. Without that block the CLI tries a static api key when the device
+offers and, until 2027.3.0, falls back to plaintext with a warning when the
+offer is missing or the handshake fails; a runtime provisioned key never
+reaches the CLI, so those uploads stay plaintext.
+
+Defeating any of that without the key is in scope: a device that requires
+encryption accepting a plaintext or downgraded upload, getting past the MAC,
+or recovering image contents from captured traffic.
+
+The following are **not** vulnerabilities, by design:
+
+- Plaintext OTA on a device with no `ota: encryption:` block, including one
+  that offers encryption because it has an api key. That is the documented
+  default, authenticated (if at all) by the OTA password. An uploader that
+  takes the offer skips the password; the key authenticates it. With a
+  runtime provisioned key and no `provisioning:` window, whoever provisions
+  the key gains that upload path too; validation warns about the pair.
+- The CLI plaintext fallback until 2027.3.0: without `ota: encryption:` an
+  active attacker who strips the offer or breaks the handshake can make a
+  keyed CLI upload plaintext, with the pre-existing plaintext exposure. A
+  device that requires encryption still refuses that upload.
+- The enablement window: firmware built with a static api key already offers
+  encryption, so turning on `ota: encryption:` is itself an encrypted upload.
+  Older firmware needs one last plaintext upload of an offering build, with
+  the pre-existing plaintext exposure.
+- The web OTA `/update` endpoint alongside encryption. With the `web_server`
+  or `prometheus` component the shared listener is always up, so the endpoint
+  stays reachable and validation warns about that combination;
+  `captive_portal:` alone brings the listener up only for the fallback AP
+  window, which is the intended recovery path, so that is not warned about.
+- CLI retry behavior on transport or MAC failures; every attempt renegotiates
+  a fresh handshake with fresh ephemerals, so retrying does not weaken
+  authentication.
+
 ## Explicitly out of scope
 
 - Local attackers who already have shell access on the host that runs `esphome`.

docker/Dockerfile

@@ -22,16 +22,13 @@ RUN \
     -r /requirements.txt
 
 # Install the ESPHome Device Builder dashboard.
-RUN uv pip install --no-cache-dir esphome-device-builder==1.12.4
+RUN uv pip install --no-cache-dir esphome-device-builder==1.16.0
 
 RUN \
     platformio settings set enable_telemetry No \
     && platformio settings set check_platformio_interval 1000000 \
     && mkdir -p /piolibs
 
-COPY script/platformio_install_deps.py platformio.ini /
-RUN /platformio_install_deps.py /platformio.ini --libraries
-
 ARG BUILD_VERSION
 
 LABEL \

docker/generate_tags.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 import argparse
+import os
 import re
 
 CHANNEL_DEV = "dev"
@@ -64,7 +65,10 @@ def main():
 
     suffix = f"-{args.suffix}" if args.suffix else ""
 
-    image_name = f"esphome/esphome{suffix}"
+    repository = (
+        (os.environ.get("GITHUB_REPOSITORY") or "esphome/esphome").strip().lower()
+    )
+    image_name = f"{repository}{suffix}"
 
     print(f"channel={channel}")
 

docker/ha-addon-rootfs/etc/s6-overlay/s6-rc.d/discovery/run

@@ -4,7 +4,6 @@
 # Home Assistant Add-on: ESPHome
 # Sends discovery information to Home Assistant.
 # ==============================================================================
-declare config
 declare port
 
 # We only disable it when disabled explicitly
@@ -19,14 +18,17 @@ port=$(bashio::addon.ingress_port)
 # Wait for the ESPHome Device Builder to become available
 bashio::net.wait_for "${port}" "127.0.0.1" 300
 
-config=$(\
-    bashio::var.json \
-        host "127.0.0.1" \
-        port "^${port}" \
-)
+# Send one discovery message; the config is a JSON string built with bashio::var.json.
+send_discovery() {
+    local service=$1
+    local config=$2
+    if bashio::discovery "${service}" "${config}" > /dev/null; then
+        bashio::log.info "Successfully send ${service} discovery information to Home Assistant."
+    else
+        bashio::log.error "${service} discovery message to Home Assistant failed!"
+    fi
+}
 
-if bashio::discovery "esphome" "${config}" > /dev/null; then
-    bashio::log.info "Successfully send discovery information to Home Assistant."
-else
-    bashio::log.error "Discovery message to Home Assistant failed!"
-fi
+send_discovery "esphome" "$(bashio::var.json host "127.0.0.1" port "^${port}")"
+# The Device Builder MCP server, consumed by Home Assistant's mcp integration.
+send_discovery "mcp" "$(bashio::var.json url "http://127.0.0.1:${port}/api/mcp")"

docker/test_configs/bk72xx-arduino.yaml

@@ -5,3 +5,15 @@ bk72xx:
   board: generic-bk7231n-qfn32-tuya
 
 logger:
+
+wifi:
+  ssid: MySSID
+  password: password1
+  ap:
+
+# mqtt and captive_portal together pull in AsyncTCP and ESPAsyncWebServer;
+# a stray ESP32 AsyncTCP copy on the library search path breaks this build
+captive_portal:
+
+mqtt:
+  broker: 192.168.178.84

esphome/__main__.py

@@ -16,6 +16,7 @@ from typing import TYPE_CHECKING, Protocol
 # cause them to be loaded before external components are processed, resulting
 # in the built-in version being used instead of the external component one.
 from esphome import const, platform_hooks
+from esphome.build_helpers.native import analysis_backend, native_backend
 from esphome.const import (
     ALLOWED_NAME_CHARS,
     ARGUMENT_HELP_DEVICE,
@@ -26,7 +27,9 @@ from esphome.const import (
     CONF_DEASSERT_RTS_DTR,
     CONF_DISABLED,
     CONF_DISCOVER_IP,
+    CONF_ENCRYPTION,
     CONF_ESPHOME,
+    CONF_KEY,
     CONF_LEVEL,
     CONF_LOG,
     CONF_LOG_TOPIC,
@@ -815,7 +818,9 @@ def write_cpp_file() -> int:
         from esphome.build_gen import espidf
 
         espidf.write_project()
-    else:
+    elif not CORE.using_native_toolchain:
+        # Other native builds generate their project at compile time;
+        # never write a platformio.ini for them
         from esphome.build_gen import platformio
 
         platformio.write_project()
@@ -857,7 +862,14 @@ def compile_program(args: ArgsProtocol, config: ConfigType) -> int:
         toolchain.create_factory_bin()
         toolchain.create_ota_bin()
         toolchain.create_elf_copy()
-        toolchain.get_idedata()
+        from esphome.build_helpers.idedata import warn_if_idedata_missing
+
+        warn_if_idedata_missing(toolchain.get_idedata)
+    elif CORE.using_native_toolchain:
+        raise EsphomeError(
+            f"Toolchain '{CORE.toolchain.value}' resolved but no platform "
+            "backend claimed the build"
+        )
     else:
         from esphome.platformio import toolchain
 
@@ -960,12 +972,15 @@ def upload_using_esptool(
 
     if file is not None:
         flash_images = [FlashImage(path=file, offset="0x0")]
-    elif CORE.using_toolchain_esp_idf:
-        from esphome.espidf import toolchain
-
-        flash_images = [
-            FlashImage(path=toolchain.get_factory_firmware_path(), offset="0x0")
-        ]
+    elif (native := native_backend()) is not None:
+        # Every native backend supplies its own 0x0 flash image (bootloader
+        # and partitions included where the target needs them)
+        image = native.get_factory_firmware_path()
+        if not image.is_file():
+            raise EsphomeError(
+                f"{image} does not exist; compile the configuration first"
+            )
+        flash_images = [FlashImage(path=image, offset="0x0")]
     else:
         from esphome.platformio import toolchain
 
@@ -1320,9 +1335,32 @@ def _upload_via_native_api(
             break
 
     from esphome import espota2
+    from esphome.components.noise import static_encryption_key
 
     remote_port = int(ota_conf[CONF_PORT])
     password = ota_conf.get(CONF_PASSWORD)
+    # Fail closed: an encryption block whose key did not resolve must never
+    # fall back to a plaintext upload
+    noise_psk = None
+    plaintext_fallback = False
+    allow_plaintext_upload = False
+    if (encryption_conf := ota_conf.get(CONF_ENCRYPTION)) is not None:
+        noise_psk = encryption_conf.get(CONF_KEY)
+        allow_plaintext_upload = bool(
+            encryption_conf.get(espota2.CONF_ALLOW_PLAINTEXT_UPLOAD)
+        )
+        if not noise_psk:
+            raise EsphomeError(
+                "OTA encryption is configured but no key was resolved; "
+                "set the key under 'ota: encryption:' or 'api: encryption:'"
+            )
+        # Ensure the key is a string, as required by the underlying OTA implementation.
+        # It arrives here as a SensitiveStr which aioesphomeapi rejects.
+        noise_psk = str(noise_psk)
+    elif api_key := static_encryption_key(config.get(CONF_API) or {}):
+        # Remove before 2027.3.0: the api key is tried, falling back to plaintext
+        noise_psk = str(api_key)
+        plaintext_fallback = True
 
     def check_partition_access(option_string: str) -> None:
         if not ota_conf.get("allow_partition_access"):
@@ -1353,7 +1391,16 @@ def _upload_via_native_api(
     if ota_type == espota2.OTA_TYPE_UPDATE_BOOTLOADER:
         _validate_bootloader_binary(binary)
 
-    return espota2.run_ota(network_devices, remote_port, password, binary, ota_type)
+    return espota2.run_ota(
+        network_devices,
+        remote_port,
+        password,
+        binary,
+        ota_type,
+        noise_psk,
+        plaintext_fallback=plaintext_fallback,
+        allow_plaintext_upload=allow_plaintext_upload,
+    )
 
 
 def _upload_via_web_server(
@@ -1362,6 +1409,16 @@ def _upload_via_web_server(
     from esphome import web_server_ota
     from esphome.web_server_helpers import get_web_server_connection
 
+    if any(
+        ota_item.get(CONF_PLATFORM) == CONF_ESPHOME
+        and ota_item.get(CONF_ENCRYPTION) is not None
+        for ota_item in config.get(CONF_OTA, [])
+    ):
+        _LOGGER.warning(
+            "This config has OTA encryption, but the web_server OTA path sends "
+            "the image over plaintext HTTP; use the esphome OTA platform to "
+            "keep it confidential"
+        )
     remote_port, username, password = get_web_server_connection(config)
     return web_server_ota.run_ota(
         network_devices, remote_port, username, password, binary
@@ -1657,20 +1714,26 @@ def command_compile(args: ArgsProtocol, config: ConfigType) -> int | None:
     if exit_code != 0:
         return exit_code
     if CORE.is_host:
-        if CORE.using_toolchain_esp_idf:
-            from esphome.espidf import toolchain
-
-            program_path = str(toolchain.get_elf_path())
-        else:
-            from esphome.platformio.toolchain import get_idedata
-
-            program_path = str(get_idedata(config).firmware_elf_path)
-        _LOGGER.info("Successfully compiled program to path '%s'", program_path)
+        _LOGGER.info(
+            "Successfully compiled program to path '%s'", _host_program_path(config)
+        )
     else:
         _LOGGER.info("Successfully compiled program.")
     return 0
 
 
+def _host_program_path(config: ConfigType) -> str:
+    """Return the compiled host ELF path."""
+    if CORE.using_toolchain_esp_idf:
+        from esphome.espidf import toolchain
+
+        return str(toolchain.get_elf_path())
+    from esphome.platformio.toolchain import get_idedata
+
+    # Memoized by compile_program's own call; this is a dict lookup
+    return str(get_idedata(config).firmware_elf_path)
+
+
 def command_upload(args: ArgsProtocol, config: ConfigType) -> int | None:
     # Get devices, resolving special identifiers like OTA
     devices = choose_upload_log_host(
@@ -1715,14 +1778,7 @@ def command_run(args: ArgsProtocol, config: ConfigType) -> int | None:
         return exit_code
     _LOGGER.info("Successfully compiled program.")
     if CORE.is_host:
-        if CORE.using_toolchain_esp_idf:
-            from esphome.espidf import toolchain
-
-            program_path = str(toolchain.get_elf_path())
-        else:
-            from esphome.platformio.toolchain import get_idedata
-
-            program_path = str(get_idedata(config).firmware_elf_path)
+        program_path = _host_program_path(config)
         _LOGGER.info("Running program from path '%s'", program_path)
         return run_external_process(program_path)
 
@@ -1914,12 +1970,12 @@ def command_update_all(args: ArgsProtocol) -> int | None:
 def command_idedata(args: ArgsProtocol, config: ConfigType) -> int:
     import json
 
-    if CORE.using_toolchain_esp_idf:
-        # Native ESP-IDF derives idedata from the build's compile_commands.json,
-        # so the configuration must already be compiled.
-        from esphome.espidf import toolchain as espidf_toolchain
+    native_toolchain = native_backend()
 
-        idedata = espidf_toolchain.get_idedata()
+    if native_toolchain is not None:
+        # Native toolchains derive idedata from the build's
+        # compile_commands.json, so the configuration must already be compiled.
+        idedata = native_toolchain.get_idedata()
         if idedata is None:
             _LOGGER.error(
                 "No idedata available; compile the configuration first",
@@ -1958,6 +2014,17 @@ def command_analyze_memory(args: ArgsProtocol, config: ConfigType) -> int:
     from esphome.analyze_memory.cli import MemoryAnalyzerCLI
     from esphome.analyze_memory.ram_strings import RamStringsAnalyzer
 
+    # Refuse an unsupported toolchain before paying for a full compile
+    analysis_toolchain = analysis_backend()
+    if analysis_toolchain is None and not CORE.using_toolchain_platformio:
+        _LOGGER.error(
+            "analyze-memory is not supported with the '%s' toolchain on %s; "
+            "re-run with --toolchain platformio",
+            CORE.toolchain.value if CORE.toolchain else "unresolved",
+            CORE.target_platform,
+        )
+        return 1
+
     # Always compile to ensure fresh data (fast if no changes - just relinks)
     exit_code = write_cpp(config)
     if exit_code != 0:
@@ -1969,13 +2036,30 @@ def command_analyze_memory(args: ArgsProtocol, config: ConfigType) -> int:
 
     # Get idedata for analysis
     idedata = None
-    if CORE.using_toolchain_esp_idf:
-        from esphome.espidf import toolchain
+    if analysis_toolchain is not None:
+        objdump = analysis_toolchain.get_objdump_path()
+        readelf = analysis_toolchain.get_readelf_path()
+        for tool in (objdump, readelf):
+            if not tool.is_file():
+                # The analyzer would silently fall back to host
+                # binutils, which cannot read the target ELF
+                _LOGGER.error(
+                    "%s is missing; the toolchain install may be incomplete "
+                    "(recompile, or run 'esphome clean-all' if it persists)",
+                    tool,
+                )
+                return 1
+        objdump_path = str(objdump)
+        readelf_path = str(readelf)
 
-        objdump_path = str(toolchain.get_objdump_path())
-        readelf_path = str(toolchain.get_readelf_path())
-
-        firmware_elf = toolchain.get_elf_path()
+        firmware_elf = analysis_toolchain.get_elf_path()
+        if not firmware_elf.is_file():
+            # The analyzer swallows tool failures, so a missing ELF would
+            # produce an exit-0 zeroed report
+            _LOGGER.error(
+                "%s is missing; compile the configuration first", firmware_elf
+            )
+            return 1
     else:
         from esphome.platformio import toolchain
 
@@ -2721,10 +2805,14 @@ def run_esphome(argv):
     # Skipped when -s overrides are passed, since the cache was written
     # against the previous substitution set.
     config: ConfigType | None = None
-    cache_eligible = (
+    cache_write_eligible = (
         args.command in ("upload", "logs") and not command_line_substitutions
     )
-    if cache_eligible:
+    # An explicit --toolchain must re-run the per-platform validators, so
+    # gate only the cache read; the refresh below saves the result unless
+    # the sidecar records a different toolchain.
+    cache_read_eligible = cache_write_eligible and args.toolchain is None
+    if cache_read_eligible:
         from esphome.compiled_config import load_compiled_config
 
         config = load_compiled_config(conf_path)
@@ -2748,17 +2836,14 @@ def run_esphome(argv):
             return 2
     CORE.config = config
 
-    # Fallback for platforms whose validators didn't set the toolchain
-    # (only the esp32 component reads esp32.framework.toolchain). All
-    # other platforms only support PlatformIO today. Must run before the
-    # cache refresh below so its sidecar records the same toolchain a
-    # compile would.
+    # The cache fast path skips validation, and legacy sidecars lack the
+    # toolchain field. Must run before the cache refresh below.
     if CORE.toolchain is None:
         CORE.toolchain = Toolchain.PLATFORMIO
 
     # Refresh the cache so the next upload/logs hits the fast path
     # instead of re-running read_config.
-    if cache_eligible and cache_missed:
+    if cache_write_eligible and cache_missed:
         from esphome.compiled_config import save_compiled_config_and_sidecar
 
         save_compiled_config_and_sidecar(config)

esphome/analyze_memory/toolchain.py

@@ -68,12 +68,16 @@ def idedata_candidates(build_path: Path) -> list[Path]:
         The candidate idedata JSON paths, most specific first
     """
     name = build_path.name
+    data_dir = build_path.parent.parent / "idedata"
+    # Native backends suffix the cache by toolchain (<name>.arduino.json)
+    suffixed = sorted(data_dir.glob(f"{name}.*.json")) if data_dir.is_dir() else []
     return [
         # In .pioenvs for test builds
         build_path / ".pioenvs" / name / "idedata.json",
         # Both toolchains cache it in the data dir, which holds this build dir:
         # <data_dir>/idedata/<name>.json next to <data_dir>/build/<name>
         build_path.parent.parent / "idedata" / f"{name}.json",
+        *suffixed,
         # Regular builds, invoked from the config dir or from anywhere
         Path.cwd() / ".esphome" / "idedata" / f"{name}.json",
         Path.home() / ".esphome" / "idedata" / f"{name}.json",

esphome/api_client.py

@@ -23,9 +23,7 @@ from esphome.util import safe_print
 if TYPE_CHECKING:
     from collections.abc import Callable
 
-    from aioesphomeapi.api_pb2 import (
-        SubscribeLogsResponse,  # pylint: disable=no-name-in-module
-    )
+    from aioesphomeapi.api_pb2 import SubscribeLogsResponse  # pylint: disable=no-name-in-module
 
 
 _LOGGER = logging.getLogger(__name__)

esphome/arduino/library.py

@@ -0,0 +1,531 @@
+"""Arduino-core backend for the shared PlatformIO library converter.
+
+Bundled names build straight from the framework tree; everything else goes
+through ``esphome.platformio.library``. Mirrors ``lib_ldf_mode=off``: each
+library builds its own archive; all include dirs join one global path.
+
+Deviations from PlatformIO: flat-layout libraries get the recursive default
+source filter; ``dot_a_linkage`` is honored; bundled libraries never run a
+manifest ``extraScript``; manifest ``-I`` flags join the global include path;
+``precompiled``/``ldflags`` properties are refused by name.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+import logging
+from pathlib import Path
+import re
+
+from esphome.core import CORE, EsphomeError, Library
+from esphome.helpers import walk_files
+from esphome.platformio.extra_script import apply_extra_script
+from esphome.platformio.library import (
+    DEFAULT_BUILD_INCLUDE_DIR,
+    DEFAULT_BUILD_SRC_FILTER,
+    ESPHOME_DATA_KEY,
+    ESPHOME_DATA_LINK_FLAGS_KEY,
+    LIBRARY_HEADER_SUFFIXES,
+    SRC_FILE_EXTENSIONS,
+    ConvertedLibrary,
+    IncompatiblePlatform,
+    InvalidLibrary,
+    LibraryBackend,
+    _url_or_none,
+    check_library_data,
+    collect_filtered_files,
+    convert_libraries,
+    ensure_list,
+    is_lib_ignored,
+    lex_build_flags,
+    lib_ignore_set,
+    normalize_dependencies,
+    parse_library_json,
+    parse_library_properties,
+    warn_properties_depends,
+)
+
+_LOGGER = logging.getLogger(__name__)
+
+
+@dataclass
+class ArduinoLibrary:
+    """One resolved library, ready for the ninja generator."""
+
+    name: str
+    sources: list[Path] = field(default_factory=list)
+    include_dirs: list[Path] = field(default_factory=list)
+    # Extra compile flags private to this library's own sources
+    flags: list[str] = field(default_factory=list)
+    # PlatformIO's build.libArchive / Arduino's dot_a_linkage: when False the
+    # objects go to the linker directly (symbols nothing references survive)
+    lib_archive: bool = True
+    # Link inputs the library contributes (-L dirs / -l libs, e.g. from
+    # precompiled vendor blobs) and -Wl, options for the firmware link
+    link_dirs: list[Path] = field(default_factory=list)
+    link_libs: list[str] = field(default_factory=list)
+    link_flags: list[str] = field(default_factory=list)
+
+
+# Source-like suffixes the case-sensitive suffix map rejects
+_UNMAPPED_SOURCE_SUFFIXES = frozenset(
+    {s.lower() for s in SRC_FILE_EXTENSIONS} | {".ino"}
+)
+
+# Filename-plain names: an allowlist excludes separators, drive colons,
+# and dot-only names by shape
+_SAFE_LIBRARY_NAME_RE = re.compile(r"[A-Za-z0-9_][A-Za-z0-9_. +-]*\Z")
+
+
+def _is_safe_library_name(name: object) -> bool:
+    """Whether a name may be joined under the framework's libraries dir."""
+    return isinstance(name, str) and _SAFE_LIBRARY_NAME_RE.fullmatch(name) is not None
+
+
+def _manifest_build(name: str, data: object) -> dict:
+    """The manifest's ``build`` section; malformed manifests fail by name."""
+    build = data.get("build", {}) if isinstance(data, dict) else None
+    if not isinstance(build, dict):
+        raise EsphomeError(f"Library {name} has a malformed manifest")
+    return build
+
+
+def _resolve_src_dir(name: str, read_path: Path, build: dict) -> str:
+    """Resolve PIO's source dir: manifest srcDir, else src/Src, else the root."""
+    if "srcDir" not in build:
+        return next((d for d in ("src", "Src") if (read_path / d).is_dir()), ".")
+    # A declared srcDir (falsy included) that does not resolve is a manifest error
+    src_dir = build["srcDir"]
+    if not (isinstance(src_dir, str) and src_dir and (read_path / src_dir).is_dir()):
+        raise EsphomeError(
+            f"Library {name} declares srcDir {src_dir!r} which does not exist"
+        )
+    return src_dir
+
+
+def _reject_unsupported_link_fields(name: str, data: dict) -> None:
+    # PIO honors these; ignoring them would fail at link with no stated
+    # cause. Property values are strings, so "false" is not a declaration.
+    precompiled = data.get("precompiled")
+    if precompiled and str(precompiled).strip().lower() != "false":
+        raise EsphomeError(
+            f"Library {name} declares precompiled, which this backend does not support"
+        )
+    if data.get("ldflags"):
+        raise EsphomeError(
+            f"Library {name} declares ldflags, which this backend does not support"
+        )
+
+
+def _resolve_lib_archive(name: str, data: dict, build: dict) -> bool:
+    """build.libArchive, else dot_a_linkage (an Arduino IDE property PIO
+    ignores; a deliberate extra), else archive."""
+
+    # Strict parse: bool("false") is True
+    def _parse(key: str, raw: object) -> bool:
+        if isinstance(raw, bool):
+            return raw
+        value = str(raw).strip().lower()
+        if value in ("true", "false"):
+            return value == "true"
+        raise EsphomeError(f"Library {name} has a malformed {key} value {raw!r}")
+
+    if "libArchive" in build:
+        return _parse("libArchive", build["libArchive"])
+    if "dot_a_linkage" in data:
+        return _parse("dot_a_linkage", data["dot_a_linkage"])
+    return True
+
+
+def _classify_build_flags(
+    name: str, read_path: Path, lib: ArduinoLibrary, flag_tokens: list[str]
+) -> list[str]:
+    """Route the lexed build.flags into the library's flag lists.
+
+    Returns the ``-I`` arguments for the include-dir resolution.
+    """
+    include_flags: list[str] = []
+    for tok in flag_tokens:
+        if tok.startswith("-I"):
+            include_flags.append(tok[2:])
+        elif tok.startswith("-L"):
+            link_dir = (read_path / tok[2:]).resolve()
+            if not link_dir.is_dir():
+                # Kept (the linker ignores missing -L dirs); the warning
+                # names the culprit before a bare "cannot find -lfoo"
+                _LOGGER.warning(
+                    "Library %s declares library dir %s which does not exist",
+                    name,
+                    tok[2:],
+                )
+            lib.link_dirs.append(link_dir)
+        elif tok.startswith("-l"):
+            lib.link_libs.append(tok[2:])
+        elif tok.startswith("-Wl,"):
+            lib.link_flags.append(tok)
+        else:
+            lib.flags.append(tok)
+    return include_flags
+
+
+def _resolve_include_dirs(
+    name: str,
+    read_path: Path,
+    lib: ArduinoLibrary,
+    build: dict,
+    src_dir: str,
+    include_flags: list[str],
+) -> None:
+    include_dir = build.get("includeDir", DEFAULT_BUILD_INCLUDE_DIR)
+    if not isinstance(include_dir, str):
+        raise EsphomeError(f"Library {name} has a malformed includeDir")
+    for d, explicit in [
+        (include_dir, "includeDir" in build),
+        (src_dir, False),  # _resolve_src_dir already validated it
+        *((flag, True) for flag in include_flags),
+    ]:
+        if (path := (read_path / d)).is_dir():
+            lib.include_dirs.append(path.resolve())
+        elif explicit:
+            # Warn-and-drop (unlike srcDir): a missing include dir is
+            # harmless until a header is needed, and the compile names it
+            _LOGGER.warning(
+                "Library %s declares include dir %s which does not exist", name, d
+            )
+
+
+def _collect_lib_sources(
+    name: str,
+    read_path: Path,
+    lib: ArduinoLibrary,
+    src_dir: str,
+    src_filter: list[str],
+) -> None:
+    sources: list[Path] = []
+    dropped: list[str] = []
+    saw_header = False
+    for f in collect_filtered_files(read_path / src_dir, src_filter):
+        path = Path(f)
+        suffix = path.suffix
+        if suffix in SRC_FILE_EXTENSIONS:
+            # resolve() per file: srcFilter patterns may escape src_dir
+            sources.append(path.resolve())
+        elif suffix.lower() in _UNMAPPED_SOURCE_SUFFIXES:
+            # A source-like suffix the case-sensitive map rejects (.CPP,
+            # .ino) is a dropped compilation unit; headers fall through
+            dropped.append(path.name)
+        elif suffix.lower() in LIBRARY_HEADER_SUFFIXES:
+            saw_header = True
+    lib.sources = sorted(sources)
+    if dropped:
+        _LOGGER.warning(
+            "Library %s: %d file(s) with unmapped source suffixes are not compiled: %s",
+            name,
+            len(dropped),
+            ", ".join(sorted(dropped)),
+        )
+    if not lib.sources and not saw_header:
+        # Matched headers mean header-only; a filter matching nothing is
+        # a manifest/tree problem (a truly empty tree raises elsewhere)
+        _LOGGER.warning("Library %s: no source files matched", name)
+
+
+def _library_info(name: str, read_path: Path, data: dict) -> ArduinoLibrary:
+    """Resolve one library's sources, include dirs, and flags (PIO semantics)."""
+    build = _manifest_build(name, data)
+    _reject_unsupported_link_fields(name, data)
+    src_dir = _resolve_src_dir(name, read_path, build)
+    src_filter = ensure_list(build.get("srcFilter", DEFAULT_BUILD_SRC_FILTER))
+    if not all(isinstance(entry, str) for entry in src_filter):
+        raise EsphomeError(f"Library {name} has a malformed srcFilter")
+    lib = ArduinoLibrary(name=name, lib_archive=_resolve_lib_archive(name, data, build))
+    # PlatformIO shell-lexes each build.flags entry
+    include_flags = _classify_build_flags(
+        name, read_path, lib, lex_build_flags(build.get("flags", []), f"library {name}")
+    )
+    _resolve_include_dirs(name, read_path, lib, build, src_dir, include_flags)
+    _collect_lib_sources(name, read_path, lib, src_dir, src_filter)
+    return lib
+
+
+def _bundled_library(framework_path: Path, name: str) -> ArduinoLibrary:
+    """A library bundled with the Arduino core, read from the framework tree.
+
+    ``library.json`` wins over ``library.properties`` when both exist, as in
+    PlatformIO's LibBuilderFactory; only the JSON manifest can carry a
+    ``build`` section (srcDir, srcFilter, flags).
+    """
+    lib_dir = framework_path / "libraries" / name
+    manifest_json = lib_dir / "library.json"
+    if manifest_json.is_file():
+        try:
+            data = parse_library_json(manifest_json)
+        except ValueError as err:  # JSONDecodeError
+            raise EsphomeError(
+                f"Bundled library {name} has a corrupt library.json ({err}); "
+                "the framework install may be incomplete (run 'esphome clean-all')"
+            ) from err
+    elif (manifest := lib_dir / "library.properties").is_file():
+        data = parse_library_properties(manifest)
+    else:
+        # Debug, not warning: the legacy manifest-less layout is legal and
+        # the 3.1.2 core ships one such library (FSTools), so a warning
+        # would be unactionable noise on every build using it
+        _LOGGER.debug("Bundled library %s has no manifest; using defaults", name)
+        data = {}
+    if isinstance(data, dict):
+        # Bundled manifest deps are never walked; make the skip visible
+        if data.get("dependencies"):
+            _LOGGER.warning(
+                "Bundled library %s declares dependencies, which are not "
+                "resolved automatically; add them with add_library() if needed",
+                name,
+            )
+        warn_properties_depends(name, data)
+        build = data.get("build")
+        if isinstance(build, dict) and build.get("extraScript"):
+            # Scripts only run on the converted path; building without
+            # the script's flags would miscompile
+            raise EsphomeError(
+                f"Bundled library {name} declares an extraScript, which is "
+                "not run for bundled libraries"
+            )
+    lib = _library_info(name, lib_dir, data)
+    _assert_tree_has_code(
+        name,
+        lib_dir,
+        "the framework install may be incomplete (run 'esphome clean-all')",
+    )
+    return lib
+
+
+def _assert_tree_has_code(name: str, root: Path, hint: str) -> None:
+    """An empty or half-extracted tree can never link; fail by name (a
+    warning would scroll away and resurface as undefined symbols)."""
+    if not any(
+        Path(p).suffix in SRC_FILE_EXTENSIONS
+        or Path(p).suffix.lower() in LIBRARY_HEADER_SUFFIXES
+        for p in walk_files(root)
+    ):
+        raise EsphomeError(f"Library {name} has no sources or headers; {hint}")
+
+
+def _external_short_name(name: str) -> str:
+    """The short library name of a requested spec.
+
+    "owner/Name" and plain names take the last path segment; "Name=<url>"
+    takes the declared name. Git tails (".git", "#ref") are stripped like
+    the walk's URL normalization; the comparand is a manifest dependency
+    name, never a spec.
+    """
+    head, sep, tail = name.partition("=")
+    if sep and "://" in tail:
+        return head
+    short = name.rsplit("/", maxsplit=1)[-1]
+    return short.partition("#")[0].removesuffix(".git")
+
+
+def _check_unfulfilled_provides(
+    provided_requests: set[str], satisfied: set[str], still_requested: set[str]
+) -> None:
+    """Fail by name when a walk-skipped dependency was never added.
+
+    An unfulfilled provides() promise only surfaces as undefined symbols
+    at link. The walk records across re-resolutions, so a name no final
+    manifest still requests is stale state, never a failure.
+    """
+    if missing := sorted((provided_requests & still_requested) - satisfied):
+        raise EsphomeError(
+            "provides() skipped these dependencies but nothing added them: "
+            f"{', '.join(missing)}; the build is missing libraries"
+        )
+
+
+def resolve_libraries(
+    framework_path: Path, *, pio_platform: str, board_mcu: str, cache_key: str
+) -> list[ArduinoLibrary]:
+    """Resolve every ``cg.add_library()`` entry into an :class:`ArduinoLibrary`.
+
+    ``pio_platform``/``board_mcu`` filter manifests the way PlatformIO would
+    for that core (e.g. ``espressif8266``/``esp8266``); ``cache_key`` keys the
+    shared converter's download cache.
+
+    The returned list is not topologically sorted, so the caller must link
+    the archives inside one ``--start-group``/``--end-group`` pair (the
+    bundled-first grouping is incidental).
+    """
+    bundled: list[ArduinoLibrary] = []
+    external: list[Library] = []
+    # PlatformIO's lib_ignore covers framework-bundled libraries too; the
+    # shared converter only filters the registry/git ones.
+    lib_ignore = lib_ignore_set()
+    # Exact directory names keep membership case-sensitive everywhere
+    # (an is_dir() probe would match "wire" on macOS/Windows and build
+    # the bundled Wire twice)
+    libraries_dir = framework_path / "libraries"
+    if not libraries_dir.is_dir():
+        # A registry fallback would fail later with a misleading
+        # package-not-found error per bundled name
+        raise EsphomeError(
+            f"{libraries_dir} is missing; the framework install may be "
+            "incomplete (run 'esphome clean-all')"
+        )
+    bundled_dir_names = frozenset(p.name for p in libraries_dir.iterdir() if p.is_dir())
+
+    def _provided(name: object) -> bool:
+        return _is_safe_library_name(name) and name in bundled_dir_names
+
+    for library in CORE.platformio_libraries.values():
+        if is_lib_ignored(library.name, lib_ignore):
+            continue
+        # Bundled only for a bare name with a matching framework dir; pinned
+        # or unmatched names resolve from the registry, as under PlatformIO.
+        if not library.repository and not library.version and _provided(library.name):
+            # Bundled manifest deps are not walked; _bundled_library warns
+            bundled.append(_bundled_library(framework_path, library.name))
+        else:
+            external.append(library)
+
+    converted: list[ArduinoLibrary] = []
+    bundled_names = {lib.name for lib in bundled}
+    converted_manifest_names: set[str] = set()
+    # Bundled candidates skipped on purpose (platform filter); the
+    # provides() reconciliation must count them as satisfied
+    knowingly_skipped: set[str] = set()
+    # Dependency names of the manifests actually emitted; a walk recording
+    # for a since-re-resolved manifest must not fail the reconciliation
+    final_dep_names: set[str] = set()
+    # Ordered set of bundled dependency names to add once conversion is done
+    pending_bundled: dict[str, None] = {}
+    # Deps matching a separately-requested external are already in the build
+    # (a duplicate archive means duplicate-symbol link errors)
+    external_short_names = {
+        _external_short_name(lib.name) for lib in external if lib.name
+    }
+
+    def _add_bundled_dependencies(component: ConvertedLibrary) -> None:
+        # A version-less bare name ("Hash") is a core-bundled library the
+        # shared converter cannot resolve from the registry
+        for dep in normalize_dependencies(
+            component.data.get("dependencies"), component.name
+        ):
+            # normalize_dependencies guarantees a non-empty str name
+            name = dep["name"]
+            final_dep_names.add(name)
+            if "/" in name:
+                owner, _, pkg = name.partition("/")
+                if _is_safe_library_name(owner) and _is_safe_library_name(pkg):
+                    # Owner-qualified; the converter resolves it from the registry
+                    continue
+            if not _is_safe_library_name(name):
+                # The name becomes a path component; never join a traversal
+                _LOGGER.warning(
+                    "Ignoring malformed dependency entry %r of library %s",
+                    dep,
+                    component.name,
+                )
+                continue
+            if name in external_short_names:
+                if _provided(name):
+                    # A bundled copy is suppressed; a coincidental name
+                    # collision would surface as link errors
+                    _LOGGER.warning(
+                        "Dependency %s of %s is assumed satisfied by a "
+                        "requested external library; the bundled copy is "
+                        "not added",
+                        name,
+                        component.name,
+                    )
+                else:
+                    _LOGGER.debug(
+                        "Dependency %s of %s assumed satisfied by a requested "
+                        "external library",
+                        name,
+                        component.name,
+                    )
+                continue
+            if name in bundled_names or is_lib_ignored(name, lib_ignore):
+                continue
+            if _url_or_none(dep.get("version")) is not None:
+                # A URL names one specific source; never add the bundled copy
+                continue
+            if dep.get("owner") or not _provided(name):
+                # Only owner-less framework-tree names take the bundled
+                # copy (PIO's process_dependencies); the walk reports drops
+                continue
+            try:
+                # framework=None: the walk already warned for non-platform
+                # causes; debug keeps one fault from warning twice (pinned
+                # by test_nonplatform_rejection_warns_once_through_real_converter)
+                check_library_data(dep, pio_platform, None)
+            except IncompatiblePlatform as err:
+                # A knowing skip (platform filter), not a broken promise
+                knowingly_skipped.add(name)
+                _LOGGER.debug("Skip bundled candidate %s: %s", name, err)
+                continue
+            except InvalidLibrary as err:
+                # Malformed manifest data never counts as satisfied; the
+                # walk owns the warning (see the warns-once test above)
+                _LOGGER.debug("Skip malformed bundled candidate %s: %s", name, err)
+                continue
+            # Deferred: a later manifest name may satisfy this
+            pending_bundled.setdefault(name)
+
+    def _emit(component: ConvertedLibrary) -> None:
+        apply_extra_script(
+            component, board_mcu=lambda: board_mcu, pio_platform=pio_platform
+        )
+        _assert_tree_has_code(
+            component.get_require_name(),
+            component.source_dir,
+            "the download may be incomplete (run 'esphome clean-all')",
+        )
+        if isinstance(manifest_name := component.data.get("name"), str):
+            converted_manifest_names.add(manifest_name)
+        lib = _library_info(
+            component.get_require_name(), component.source_dir, component.data
+        )
+        # Extra-script LINKFLAGS travel outside build.flags; dropping
+        # them would link wrong with no stated cause
+        lib.link_flags.extend(
+            component.data.get(ESPHOME_DATA_KEY, {}).get(
+                ESPHOME_DATA_LINK_FLAGS_KEY, []
+            )
+        )
+        converted.append(lib)
+        _add_bundled_dependencies(component)
+
+    backend = LibraryBackend(
+        platform=pio_platform,
+        framework="arduino",
+        emit=_emit,
+        cache_key=cache_key,
+        # The walk must not resolve bundled names from the registry;
+        # _add_bundled_dependencies adds them after emit
+        provides=_provided,
+    )
+    if external:
+        convert_libraries(external, backend)
+    for name in pending_bundled:
+        if name in converted_manifest_names:
+            # The converted library is this one; the bundled copy would
+            # double the archive. Warn like the external_short_names twin.
+            _LOGGER.warning(
+                "Dependency %s is assumed satisfied by a converted library's "
+                "manifest name; the bundled copy is not added",
+                name,
+            )
+            continue
+        bundled_names.add(name)
+        bundled.append(_bundled_library(framework_path, name))
+
+    _check_unfulfilled_provides(
+        backend.provided_requests,
+        bundled_names
+        | converted_manifest_names
+        | external_short_names
+        | knowingly_skipped,
+        final_dep_names,
+    )
+
+    return bundled + converted

esphome/arduino8266/__init__.py

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

esphome/arduino8266/framework.py

@@ -0,0 +1,159 @@
+"""Download and install the Arduino ESP8266 core, toolchain, and ninja.
+
+Artifacts land in a machine-global cache (shared across projects, like the
+ESP-IDF install in ``esphome.espidf.framework``):
+
+    <cache>/arduino8266/frameworks/<version>/   framework-arduinoespressif8266
+    <cache>/arduino8266/toolchains/<version>/   toolchain-xtensa (gcc 10.3)
+
+Packages come from the PlatformIO registry (identical bits to the PlatformIO
+backend); ``ESPHOME_ARDUINO8266_*_MIRRORS`` overrides the URLs. ninja comes
+from PATH or the ninja PyPI wheel.
+"""
+
+from __future__ import annotations
+
+import os
+from pathlib import Path
+from typing import NamedTuple
+
+from esphome.build_helpers.ccache import ccache_defaults_env
+from esphome.build_helpers.ninja import find_ninja
+from esphome.build_helpers.tools_cache import ARDUINO8266_TOOLS_CACHE, tools_cache_path
+from esphome.core import EsphomeError, Version
+from esphome.framework_helpers import str_to_lst_of_str
+from esphome.platformio.registry import install_package, prefetch_packages
+
+FRAMEWORK_PACKAGE = "framework-arduinoespressif8266"
+TOOLCHAIN_PACKAGE = "toolchain-xtensa"
+# gcc 10.3, the toolchain Arduino core 3.x builds with; the build
+# generator's compile flags are tuned to it.
+TOOLCHAIN_VERSION = "2.100300.220621"
+
+ESPHOME_ARDUINO8266_FRAMEWORK_MIRRORS = str_to_lst_of_str(
+    os.environ.get("ESPHOME_ARDUINO8266_FRAMEWORK_MIRRORS", "")
+)
+ESPHOME_ARDUINO8266_TOOLCHAIN_MIRRORS = str_to_lst_of_str(
+    os.environ.get("ESPHOME_ARDUINO8266_TOOLCHAIN_MIRRORS", "")
+)
+
+
+def get_arduino8266_tools_path() -> Path:
+    # Machine-global so all projects share one install; see
+    # espidf.framework.get_idf_tools_path for the location rationale.
+    return tools_cache_path(*ARDUINO8266_TOOLS_CACHE)
+
+
+# 3.1.1 rather than 3.1.0: the registry has no packages for 3.0.0, 3.0.1 or 3.1.0
+MIN_FRAMEWORK_VERSION = Version(3, 1, 1)
+
+
+def framework_package_version(ver: Version) -> str:
+    """Map an Arduino core version to its registry package version (3.1.2 ->
+    3.30102.0; the leading 3 is the package major).
+
+    Exact registry names for 3.x cores; callers floor at MIN_FRAMEWORK_VERSION.
+    """
+    if ver.major > 3:
+        raise EsphomeError(
+            f"Arduino core {ver} is not supported yet; "
+            "the newest known core series is 3.x"
+        )
+    if ver.major < 3:
+        raise EsphomeError(
+            f"Arduino core {ver} is not supported; ESPHome requires core 3.x"
+        )
+    return f"3.{ver.major}{ver.minor:02d}{ver.patch:02d}.0"
+
+
+def get_framework_path(package_version: str) -> Path:
+    return get_arduino8266_tools_path() / "frameworks" / package_version
+
+
+def get_toolchain_path() -> Path:
+    return get_arduino8266_tools_path() / "toolchains" / TOOLCHAIN_VERSION
+
+
+class InstalledPaths(NamedTuple):
+    """Locations of the installed framework, toolchain, and ninja binary."""
+
+    framework: Path
+    toolchain: Path
+    ninja: Path
+
+
+def check_and_install(framework_version: Version) -> InstalledPaths:
+    """Ensure framework, toolchain, and ninja are installed; return their paths."""
+    if framework_version < MIN_FRAMEWORK_VERSION:
+        # Config validation enforces this too; keep the module honest when
+        # called directly.
+        raise EsphomeError(
+            f"The native toolchain requires the Arduino core "
+            f">= {MIN_FRAMEWORK_VERSION}, got {framework_version}"
+        )
+    # Probe the cheap local dependency before ~110 MB of downloads
+    ninja_path = find_ninja()
+    package_version = framework_package_version(framework_version)
+    framework_path = get_framework_path(package_version)
+    downloads_dir = get_arduino8266_tools_path() / "downloads"
+    toolchain_path = get_toolchain_path()
+    # One spec per package: the prefetch and the installs must agree
+    specs = (
+        (
+            FRAMEWORK_PACKAGE,
+            package_version,
+            framework_path,
+            ESPHOME_ARDUINO8266_FRAMEWORK_MIRRORS,
+            ("cores/esp8266", "tools/sdk", "libraries"),
+        ),
+        (
+            TOOLCHAIN_PACKAGE,
+            TOOLCHAIN_VERSION,
+            toolchain_path,
+            ESPHOME_ARDUINO8266_TOOLCHAIN_MIRRORS,
+            # xtensa-lx106-elf pins the target: every gcc package has a bin/
+            ("bin", "xtensa-lx106-elf"),
+        ),
+    )
+    # Fetch both archives at once; the installs below verify and extract
+    prefetch_packages([spec[:4] for spec in specs], downloads_dir)
+    for name, version, dest, mirrors, expect in specs:
+        install_package(name, version, dest, mirrors, downloads_dir, expect=expect)
+    return InstalledPaths(
+        framework=framework_path, toolchain=toolchain_path, ninja=ninja_path
+    )
+
+
+def toolchain_tool(toolchain_path: Path, name: str) -> Path:
+    """Path to one toolchain tool (gcc, g++, ar, size, addr2line, ...).
+
+    The single owner of the ``bin/xtensa-lx106-elf-<name>`` layout and the
+    Windows suffix, so a toolchain package bump touches one spot.
+    """
+    suffix = ".exe" if os.name == "nt" else ""
+    return toolchain_path / "bin" / f"xtensa-lx106-elf-{name}{suffix}"
+
+
+def get_build_env(toolchain_path: Path, ccache: str | None) -> dict[str, str]:
+    env = os.environ.copy()
+    # Drop empty entries: a trailing separator from an absent PATH would
+    # make the shell search the current directory for tools
+    parts = [
+        str(toolchain_path / "bin"),
+        *filter(None, env.get("PATH", "").split(os.pathsep)),
+    ]
+    env["PATH"] = os.pathsep.join(parts)
+    env.update(ccache_env(ccache))
+    return env
+
+
+def ccache_env(ccache: str | None) -> dict[str, str]:
+    """Return ccache settings for the build subprocess (not os.environ).
+
+    ``ccache`` is the pre-resolved binary (resolve_ccache_path), or None
+    when disabled. Values the user already set in the environment are
+    respected.
+    """
+    if ccache is None:
+        return {}
+    return ccache_defaults_env(get_arduino8266_tools_path() / "ccache")

esphome/arduino8266/toolchain.py

@@ -0,0 +1,266 @@
+"""Native Arduino ESP8266 build driver (the PlatformIO ``run`` equivalent)."""
+
+from __future__ import annotations
+
+import json
+import logging
+from pathlib import Path
+import subprocess
+from typing import TYPE_CHECKING
+
+from esphome.build_helpers.ccache import resolve_ccache_path
+from esphome.const import (
+    CONF_COMPILE_PROCESS_LIMIT,
+    CONF_ESPHOME,
+    KEY_CORE,
+    KEY_FRAMEWORK_VERSION,
+)
+from esphome.core import CORE, EsphomeError
+from esphome.helpers import write_file
+from esphome.types import ConfigType
+
+if TYPE_CHECKING:
+    from esphome.arduino8266.framework import InstalledPaths
+
+_LOGGER = logging.getLogger(__name__)
+
+# ESP8266 user RAM (matches upload.maximum_ram_size in every board manifest)
+_MAX_RAM_SIZE = 81920
+
+
+def _warn_ignored_platformio_options() -> None:
+    """Warn for component-added platformio options the native build drops."""
+    from esphome.core.config import NATIVE_ARDUINO_CONSUMED_PIO_OPTIONS
+
+    consumed = NATIVE_ARDUINO_CONSUMED_PIO_OPTIONS
+    for key in sorted(CORE.platformio_options or {}):
+        if key not in consumed:
+            _LOGGER.warning(
+                "platformio_options->%s is ignored when building with the "
+                "native 'arduino' toolchain",
+                key,
+            )
+
+
+_RAM_SECTIONS = (".data", ".rodata", ".bss")
+_FLASH_SECTIONS = (".irom0.text", ".text", ".text1", ".data", ".rodata")
+
+
+def get_build_dir() -> Path:
+    return CORE.relative_pioenvs_path(CORE.name)
+
+
+def get_elf_path() -> Path:
+    return get_build_dir() / "firmware.elf"
+
+
+def _toolchain_tool(name: str) -> Path:
+    # Imported here, not at module scope: the serial upload/logs fast path
+    # resolves this module for its artifact paths alone, and framework
+    # pulls in the whole package-download stack
+    from esphome.arduino8266 import framework
+
+    return framework.toolchain_tool(framework.get_toolchain_path(), name)
+
+
+def get_factory_firmware_path() -> Path:
+    """The image to serial-flash at 0x0 (same bytes as firmware.bin: the
+    8266 factory copy exists for artifact-contract parity, not content)."""
+    return get_build_dir() / "firmware.factory.bin"
+
+
+def get_addr2line_path() -> Path:
+    return _toolchain_tool("addr2line")
+
+
+def get_objdump_path() -> Path:
+    return _toolchain_tool("objdump")
+
+
+def get_readelf_path() -> Path:
+    return _toolchain_tool("readelf")
+
+
+def run_compile(config: ConfigType, verbose: bool) -> int:
+    from esphome.arduino8266 import framework
+    from esphome.build_gen import arduino8266 as build_gen
+
+    _warn_ignored_platformio_options()
+    paths = framework.check_and_install(CORE.data[KEY_CORE][KEY_FRAMEWORK_VERSION])
+    # Resolved once: the probe is not free and three consumers need it
+    ccache = resolve_ccache_path()
+    build_gen.write_project(paths, ccache)
+
+    build_dir = get_build_dir()
+    env = framework.get_build_env(paths.toolchain, ccache)
+
+    # The DB is a pure function of build.ninja; regenerate when it is older
+    compdb = build_dir / "compile_commands.json"
+    ninja_file = build_dir / "build.ninja"
+    if not compdb.is_file() or compdb.stat().st_mtime < ninja_file.stat().st_mtime:
+        _write_compile_commands(paths.ninja, build_dir, env)
+
+    cmd = [str(paths.ninja)]
+    if verbose:
+        cmd.append("-v")
+    if jobs := config[CONF_ESPHOME].get(CONF_COMPILE_PROCESS_LIMIT):
+        cmd += ["-j", str(jobs)]
+    # Explicit targets: a generator defect that drops them fails loudly
+    # instead of a green no-op run leaving stale artifacts in place
+    targets = ["firmware.factory.bin", "firmware.ota.bin"]
+    cmd += targets
+
+    # cwd, not -C: drops ninja's "Entering directory" banner
+    _LOGGER.debug("Running: %s", " ".join(cmd))
+    rc = subprocess.run(
+        cmd, cwd=build_dir, env=env, check=False, close_fds=False
+    ).returncode
+    if rc != 0:
+        return rc
+
+    # ninja already refused missing targets; existence covers a rule that
+    # ran but wrote elsewhere
+    build_dir_artifacts = (
+        get_elf_path(),
+        build_dir / "firmware.bin",
+        get_factory_firmware_path(),
+        build_dir / "firmware.ota.bin",
+    )
+    for artifact in build_dir_artifacts:
+        if not artifact.is_file():
+            _LOGGER.error("Build produced no %s", artifact)
+            return 1
+
+    if not _print_size_summary(build_dir, paths):
+        # Cause already warned; name the consequence for CI harnesses
+        _LOGGER.warning("Firmware size summary unavailable for this build")
+    from esphome.build_helpers.idedata import warn_if_idedata_missing
+
+    warn_if_idedata_missing(lambda: get_idedata(ccache))
+    return 0
+
+
+def _write_compile_commands(
+    ninja_path: Path, build_dir: Path, env: dict[str, str]
+) -> None:
+    compdb = build_dir / "compile_commands.json"
+    result = subprocess.run(
+        [str(ninja_path), "-C", str(build_dir), "-t", "compdb", "c", "cxx", "asm"],
+        env=env,
+        capture_output=True,
+        text=True,
+        check=False,
+        close_fds=False,
+    )
+    if result.returncode != 0:
+        # Drop any stale database so consumers (IDE integration, clang-tidy,
+        # the memory analyzer) can't silently read outdated data.
+        compdb.unlink(missing_ok=True)
+        raise EsphomeError(f"Could not generate compile_commands.json: {result.stderr}")
+    try:
+        entries = json.loads(result.stdout)
+    except ValueError as err:
+        compdb.unlink(missing_ok=True)
+        raise EsphomeError(
+            f"ninja produced an unparsable compile database: {err} "
+            f"(output starts {result.stdout[:120]!r})"
+        ) from err
+    if not entries:
+        # compdb exits 0 with [] for unknown rule names; a renamed compile
+        # rule must fail the build, not silently strand every consumer
+        compdb.unlink(missing_ok=True)
+        raise EsphomeError(
+            "ninja produced an empty compile database; the generator's rule "
+            "names no longer match"
+        )
+    write_file(compdb, result.stdout)
+
+
+def _parse_app_size(build_dir: Path, paths: InstalledPaths) -> int | None:
+    """Read the app flash budget (irom0_0_seg length) from the linker script."""
+    from esphome.build_gen.arduino8266 import get_flash_ld_path
+    from esphome.components.esp8266.build_surgery import segment_length
+
+    # Warnings, not debug: without the app size the Flash summary line is
+    # dropped and CI's memory-impact extraction loses its flash metric.
+    ld_path = get_flash_ld_path(build_dir, paths)
+    try:
+        ld_text = ld_path.read_text(encoding="utf-8")
+    except (OSError, UnicodeDecodeError) as err:
+        # A corrupt script degrades the same way, never aborts the build
+        _LOGGER.warning("Cannot read linker script for the Flash summary: %s", err)
+        return None
+    if not (app_size := segment_length(ld_text, "irom0_0_seg")):
+        _LOGGER.warning("No usable irom0_0_seg in %s; skipping Flash summary", ld_path)
+        return None
+    return app_size
+
+
+def _print_size_summary(build_dir: Path, paths: InstalledPaths) -> bool:
+    """Print the RAM/Flash lines ``ci_memory_impact_extract.py`` parses;
+    False when skipped."""
+    from esphome.arduino8266.framework import toolchain_tool
+    from esphome.build_helpers.size_summary import print_size_line
+
+    try:
+        result = subprocess.run(
+            [
+                str(toolchain_tool(paths.toolchain, "size")),
+                "-A",
+                "-d",
+                str(build_dir / "firmware.elf"),
+            ],
+            capture_output=True,
+            text=True,
+            check=True,
+            close_fds=False,
+        )
+    except (OSError, subprocess.CalledProcessError) as err:
+        # The summary is a bonus artifact like idedata; a truncated
+        # toolchain extraction must not discard an already-linked build
+        _LOGGER.warning("Could not summarize firmware size: %s", err)
+        return False
+    # -d prints decimal sizes; anything else trips the missing-sections guard
+    sections = {
+        parts[0]: int(parts[1])
+        for line in result.stdout.splitlines()
+        if (parts := line.split())[:1] and parts[0].startswith(".") and len(parts) >= 2
+        if parts[1].isdigit()
+    }
+    if missing := set(_RAM_SECTIONS + _FLASH_SECTIONS) - set(sections):
+        # A defaulted 0 would print a confidently wrong total for CI's metric
+        _LOGGER.warning(
+            "Size output is missing section(s) %s; skipping the size summary",
+            ", ".join(sorted(missing)),
+        )
+        return False
+    # Resolve the flash budget before printing: a RAM line without its
+    # Flash line would skew CI's memory-impact extraction
+    app_size = _parse_app_size(build_dir, paths)
+    if not app_size:
+        return False
+    ram = sum(sections[s] for s in _RAM_SECTIONS)
+    flash = sum(sections[s] for s in _FLASH_SECTIONS)
+    print_size_line("RAM", ram, _MAX_RAM_SIZE)
+    print_size_line("Flash", flash, app_size)
+    return True
+
+
+def get_idedata(ccache: str | None = None) -> dict | None:
+    """Derive idedata from the build's compile_commands.json (same
+    contract as ``espidf.toolchain.get_idedata``)."""
+    from esphome.build_helpers.idedata import load_or_build_idedata
+
+    # A disabled ccache resolves to None without spawning anything, so
+    # re-resolving here costs nothing when the caller has no answer
+    launcher = ccache or resolve_ccache_path()
+    return load_or_build_idedata(
+        get_build_dir() / "compile_commands.json",
+        get_elf_path(),
+        # Suffixed so a platformio->arduino->platformio round trip on one
+        # config never serves the other toolchain's cache shape
+        CORE.relative_internal_path("idedata", f"{CORE.name}.arduino.json"),
+        # The compile DB's commands carry the same ccache prefix the ninja
+        # rules were generated with
+        launcher=str(launcher) if launcher else None,
+    )

esphome/automation.py

@@ -1,5 +1,8 @@
+from collections.abc import Callable
 from dataclasses import dataclass, field
 import logging
+import string
+from typing import Any
 
 import esphome.codegen as cg
 import esphome.config_validation as cv
@@ -18,15 +21,17 @@ from esphome.const import (
     CONF_TYPE_ID,
     CONF_UPDATE_INTERVAL,
 )
-from esphome.core import ID, Lambda
+from esphome.core import CORE, ID, EsphomeError, Lambda
 from esphome.cpp_generator import (
+    FlashStringLiteral,
     LambdaExpression,
     MockObj,
     MockObjClass,
     TemplateArgsType,
+    call_lambda,
 )
 from esphome.schema_extractors import SCHEMA_EXTRACT, schema_extractor
-from esphome.types import ConfigType
+from esphome.types import ConfigType, SafeExpType
 from esphome.util import Registry
 
 
@@ -57,6 +62,7 @@ def maybe_conf(conf, *validators):
         with cv.remove_prepend_path([conf]):
             return validator({conf: value})
 
+    validate.inner_schema = validator
     return validate
 
 
@@ -102,6 +108,101 @@ def register_condition(name: str, condition_type: MockObjClass, schema: cv.Schem
     return CONDITION_REGISTRY.register(name, condition_type, schema)
 
 
+async def _build_with_parent(
+    config: ConfigType,
+    automation_id: ID,
+    template_arg: cg.TemplateArguments,
+    args: TemplateArgsType,
+) -> MockObj:
+    parent = await cg.get_variable(config[CONF_ID])
+    return cg.new_Pvariable(automation_id, template_arg, parent)
+
+
+async def _build_without_parent(
+    config: ConfigType,
+    automation_id: ID,
+    template_arg: cg.TemplateArguments,
+    args: TemplateArgsType,
+) -> MockObj:
+    return cg.new_Pvariable(automation_id, template_arg)
+
+
+async def _build_parented(
+    config: ConfigType,
+    automation_id: ID,
+    template_arg: cg.TemplateArguments,
+    args: TemplateArgsType,
+) -> MockObj:
+    var = cg.new_Pvariable(automation_id, template_arg)
+    await cg.register_parented(var, config[CONF_ID])
+    return var
+
+
+def register_simple_action(
+    name: str,
+    action_type: MockObjClass,
+    schema: cv.Schema,
+    *,
+    synchronous: bool,
+) -> None:
+    """Register an action whose constructor takes the object named by ``config[CONF_ID]``.
+
+    Use the ``register_action`` decorator instead when the builder must also set fields.
+    """
+    register_action(name, action_type, schema, synchronous=synchronous)(
+        _build_with_parent
+    )
+
+
+def register_simple_condition(
+    name: str, condition_type: MockObjClass, schema: cv.Schema
+) -> None:
+    """Condition counterpart of ``register_simple_action``."""
+    register_condition(name, condition_type, schema)(_build_with_parent)
+
+
+def register_bare_action(
+    name: str,
+    action_type: MockObjClass,
+    schema: cv.Schema,
+    *,
+    synchronous: bool,
+) -> None:
+    """Register an action whose constructor takes no arguments."""
+    register_action(name, action_type, schema, synchronous=synchronous)(
+        _build_without_parent
+    )
+
+
+def register_bare_condition(
+    name: str, condition_type: MockObjClass, schema: cv.Schema
+) -> None:
+    """Condition counterpart of ``register_bare_action``."""
+    register_condition(name, condition_type, schema)(_build_without_parent)
+
+
+def register_parented_action(
+    name: str,
+    action_type: MockObjClass,
+    schema: cv.Schema,
+    *,
+    synchronous: bool,
+) -> None:
+    """Register an action deriving from ``Parented<T>``.
+
+    The object is constructed without arguments and ``set_parent()`` receives the object
+    named by ``config[CONF_ID]``.
+    """
+    register_action(name, action_type, schema, synchronous=synchronous)(_build_parented)
+
+
+def register_parented_condition(
+    name: str, condition_type: MockObjClass, schema: cv.Schema
+) -> None:
+    """Condition counterpart of ``register_parented_action``."""
+    register_condition(name, condition_type, schema)(_build_parented)
+
+
 Action = cg.esphome_ns.class_("Action")
 Trigger = cg.esphome_ns.class_("Trigger")
 ACTION_REGISTRY = Registry()
@@ -112,6 +213,295 @@ validate_action_list = cv.validate_registry("action", ACTION_REGISTRY)
 validate_condition = cv.validate_registry_entry("condition", CONDITION_REGISTRY)
 validate_condition_list = cv.validate_registry("condition", CONDITION_REGISTRY)
 
+ApplyAction = cg.esphome_ns.class_("ApplyAction", Action)
+ApplyCondition = cg.esphome_ns.class_("ApplyCondition", Condition)
+
+
+def flash_string(config: ConfigType, value: str) -> str:
+    """Default renderer for ``std::string`` constants; copies the literal out of flash on ESP8266."""
+    if CORE.is_esp8266:
+        return f"progmem_string({FlashStringLiteral(value)})"
+    return str(cg.safe_exp(value))
+
+
+def literal_with_length(config: ConfigType, value: str) -> str:
+    """Renderer for a ``(const char *, size_t)`` target: a plain literal plus its byte length.
+
+    The target compares or copies the bytes in place, so it needs the RAM literal rather than
+    the PROGMEM rendering on ESP8266, and the length saves a strlen.
+    """
+    return f"{cg.safe_exp(value)}, {len(value.encode('utf-8'))}"
+
+
+@dataclass(frozen=True)
+class ApplyCall:
+    """One statement from config keys, e.g. ``"set_range({}, {})"`` with ``((CONF_LOW, cg.float_), ...)``.
+
+    Each arg is ``(conf_key, type_)`` or ``(conf_key, type_, const_fn)``. A ``conf_key`` may be a
+    path into nested sections. A plain ``str`` ``type_`` is raw C++ type text and may use
+    ``{parent}``. ``const_fn(config, value)`` renders a constant's argument text; a lambda or an
+    id bypasses it. The statement is skipped when none of its keys is set, always emitted when it
+    has no keys, and a partial set is a config error.
+    """
+
+    target: str
+    args: tuple[tuple[Any, ...], ...] = ()
+
+    def __post_init__(self) -> None:
+        fields = [
+            f for _, f, _, _ in string.Formatter().parse(self.target) if f is not None
+        ]
+        if any(fields):
+            raise ValueError(
+                f"apply target {self.target!r}: only bare {{}} placeholders"
+            )
+        if len(fields) != len(self.args):
+            raise ValueError(
+                f"apply target {self.target!r} has {len(fields)} "
+                f"placeholder(s) for {len(self.args)} config key(s)"
+            )
+        if any(len(arg) not in (2, 3) for arg in self.args):
+            raise ValueError(
+                f"apply target {self.target!r}: each arg is (conf_key, type_[, const_fn])"
+            )
+
+    @property
+    def members(self) -> list[tuple[Any, Any, Any]]:
+        """Each arg as ``(conf_key, type_, const_fn or None)``."""
+        return [
+            (arg[0], arg[1], arg[2] if len(arg) == 3 else None) for arg in self.args
+        ]
+
+
+@dataclass(frozen=True)
+class ApplyField:
+    """One config key forwarded as ``target(value)``, or as statement ``target`` when it has ``{}``.
+
+    Double a literal brace in a template. ``conf_key`` may be a path into nested sections.
+    ``type_`` may be a C++ type string using ``{parent}`` when the type is only known per
+    instance. ``const_fn(config, value)`` renders a constant's argument text when ``cg.safe_exp``
+    is not the right spelling (unit conversion belongs in the validator); a lambda or an id
+    bypasses it, so the target must also take a plain ``type_``. An absent key emits nothing.
+    """
+
+    conf_key: str | tuple[str, ...]
+    target: str
+    type_: SafeExpType
+    const_fn: Callable[[ConfigType, Any], str] | None = None
+
+    def call(self) -> ApplyCall:
+        target = self.target if "{}" in self.target else f"{self.target}({{}})"
+        return ApplyCall(target, ((self.conf_key, self.type_, self.const_fn),))
+
+
+def _config_lookup(config: ConfigType, key: str | tuple[str, ...]) -> Any:
+    if isinstance(key, str):
+        return config.get(key)
+    for part in key:
+        if (config := config.get(part)) is None:
+            return None
+    return config
+
+
+def _dict_schema(schema: Any) -> Any:
+    """The dict-backed cv.Schema inside cv.All and maybe_* wrappers, or None; cv.Any is not inspected."""
+    if isinstance(schema, dict):
+        return cv.Schema(schema)
+    if isinstance(getattr(schema, "schema", None), dict):
+        return schema
+    if isinstance(schema, cv.All):
+        inner = schema.validators
+    else:
+        inner = (
+            getattr(schema, "inner_schema", None),
+        )  # maybe_conf / maybe_simple_value
+    for candidate in inner:
+        if candidate is not None and (found := _dict_schema(candidate)) is not None:
+            return found
+    return None
+
+
+def _check_key_in_schema(
+    name: str, schema: Any, conf_key: str | tuple[str, ...]
+) -> None:
+    """Reject a key path the schema does not have; a typo would otherwise be a silent no-op.
+
+    Only dict-backed schemas, also inside cv.All and maybe_* wrappers, can be checked.
+    """
+    for part in (conf_key,) if isinstance(conf_key, str) else conf_key:
+        if (schema := _dict_schema(schema)) is None:
+            return
+        markers = {
+            getattr(marker, "schema", marker): marker for marker in schema.schema
+        }
+        if part not in markers:
+            raise ValueError(f"{name}: config key {part!r} is not in the schema")
+        schema = schema.schema[markers[part]]
+
+
+async def _apply_parent(config: ConfigType, id_key: str = CONF_ID) -> str:
+    # Global-scope qualified so a trigger arg named like the id cannot shadow it.
+    return f"::{await cg.get_variable(config[id_key])}"
+
+
+def _apply_lambda_args(args: TemplateArgsType) -> TemplateArgsType:
+    # Must match ApplyAction::ApplyFn and ApplyCondition::CheckFn exactly for the function
+    # pointer conversion.
+    return [
+        (cg.RawExpression(f"const std::remove_cvref_t<{cg.safe_exp(t)}> &"), arg)
+        for t, arg in args
+    ]
+
+
+async def _render_values(
+    name: str,
+    target: str,
+    members: list[tuple[Any, Any, Any]],
+    values: list[Any],
+    config: ConfigType,
+    parent: str,
+    lambda_args: TemplateArgsType,
+    compare: bool = False,
+) -> list[str]:
+    """Render the argument text of one statement; every key must be present.
+
+    ``compare``: an inlined lambda expression is parenthesized so it binds as a whole
+    beside an operator.
+    """
+    if any(value is None for value in values):
+        keys = [key for key, _, _ in members]
+        raise EsphomeError(f"{name}: {target!r} needs all of {keys}")
+    exprs: list[str] = []
+    for (_, type_, const_fn), value in zip(members, values, strict=True):
+        if isinstance(value, Lambda):
+            if isinstance(type_, str):
+                type_ = cg.RawExpression(type_.format(parent=parent))
+            inner = await cg.process_lambda(value, lambda_args, return_type=type_)
+            expr = call_lambda(inner)
+            bare = compare and isinstance(expr, cg.RawExpression)
+            exprs.append(f"({expr})" if bare else str(expr))
+        elif isinstance(value, ID):
+            # Qualified like the parent, so a trigger arg named like the id cannot shadow it.
+            exprs.append(f"::{await cg.get_variable(value)}")
+        elif const_fn is not None:
+            exprs.append(const_fn(config, value))
+        else:
+            exprs.append(str(cg.safe_exp(value)))
+    return exprs
+
+
+def _apply_values(config: ConfigType, members: list[tuple[Any, Any, Any]]) -> list[Any]:
+    return [_config_lookup(config, key) for key, _, _ in members]
+
+
+def register_apply_action(
+    name: str,
+    schema: cv.Schema,
+    *fields: ApplyField | ApplyCall,
+    call: str | None = None,
+    id_key: str = CONF_ID,
+) -> None:
+    """Register an action that only forwards config values to its parent, with no C++ class.
+
+    Generates one stateless function for ``ApplyAction<Ts...>``: the parent (read from
+    ``id_key``) and constants are baked in, lambdas are called inline with the trigger args.
+    A constant that is an id (``cv.use_id`` under ``cv.templatable``) is the object it names.
+    With ``call`` every statement targets the call object ``auto apply_call = parent->call()``,
+    and ``apply_call.perform()`` is appended.
+    """
+    # An action stores the value, so a std::string constant stays in flash on ESP8266.
+    statements_spec = [
+        (
+            c.target,
+            [
+                (key, t, fn or (flash_string if t is cg.std_string else None))
+                for key, t, fn in c.members
+            ],
+        )
+        for c in (f if isinstance(f, ApplyCall) else f.call() for f in fields)
+    ]
+    _check_key_in_schema(name, schema, id_key)
+    for _, members in statements_spec:
+        for conf_key, _, _ in members:
+            _check_key_in_schema(name, schema, conf_key)
+
+    async def builder(
+        config: ConfigType,
+        action_id: ID,
+        template_arg: cg.TemplateArguments,
+        args: TemplateArgsType,
+    ) -> MockObj:
+        parent = await _apply_parent(config, id_key)
+        lambda_args = _apply_lambda_args(args)
+        receiver = "apply_call." if call else f"{parent}->"
+        statements: list[str] = []
+        for target, members in statements_spec:
+            values = _apply_values(config, members)
+            if members and all(value is None for value in values):
+                continue
+            exprs = await _render_values(
+                name, target, members, values, config, parent, lambda_args
+            )
+            statements.append(f"{receiver}{target.format(*exprs)};")
+        if call:
+            statements = [
+                f"auto apply_call = {parent}->{call}();",
+                *statements,
+                "apply_call.perform();",
+            ]
+        apply_lambda = LambdaExpression(
+            ["\n".join(statements)], lambda_args, capture="", return_type=cg.void
+        )
+        return cg.new_Pvariable(action_id, template_arg, apply_lambda)
+
+    register_action(name, ApplyAction, schema, synchronous=True)(builder)
+
+
+def register_apply_condition(
+    name: str, schema: cv.Schema, check: str | ApplyCall, id_key: str = CONF_ID
+) -> None:
+    """Register a condition that is one expression on its parent, with no C++ class.
+
+    ``check`` is applied to the parent: ``"is_playing()"`` becomes ``parent->is_playing()``; an
+    ``ApplyCall`` such as ``ApplyCall("state == {}", ((CONF_STATE, cg.bool_),))`` compares
+    against config values, all of which must be present. Write ``== false`` to negate.
+    String constants are plain literals, so compare a ``std::string`` or ``StringRef`` member.
+    Generates one stateless function for ``ApplyCondition<Ts...>``.
+    """
+    call = check if isinstance(check, ApplyCall) else ApplyCall(check)
+    members = call.members
+    _check_key_in_schema(name, schema, id_key)
+    for conf_key, _, _ in members:
+        _check_key_in_schema(name, schema, conf_key)
+
+    async def builder(
+        config: ConfigType,
+        condition_id: ID,
+        template_arg: cg.TemplateArguments,
+        args: TemplateArgsType,
+    ) -> MockObj:
+        parent = await _apply_parent(config, id_key)
+        lambda_args = _apply_lambda_args(args)
+        exprs = await _render_values(
+            name,
+            call.target,
+            members,
+            _apply_values(config, members),
+            config,
+            parent,
+            lambda_args,
+            compare=True,
+        )
+        check_lambda = LambdaExpression(
+            [f"return {parent}->{call.target.format(*exprs)};"],
+            lambda_args,
+            capture="",
+            return_type=cg.bool_,
+        )
+        return cg.new_Pvariable(condition_id, template_arg, check_lambda)
+
+    register_condition(name, ApplyCondition, schema)(builder)
+
 
 def validate_potentially_and_condition(value):
     if isinstance(value, list):
@@ -359,28 +749,15 @@ async def for_condition_to_code(
     return var
 
 
-@register_condition(
+register_apply_condition(
     "component.is_idle",
-    LambdaCondition,
     maybe_simple_id(
         {
             cv.Required(CONF_ID): cv.use_id(cg.Component),
         }
     ),
+    "is_idle()",
 )
-async def component_is_idle_condition_to_code(
-    config: ConfigType,
-    condition_id: ID,
-    template_arg: cg.TemplateArguments,
-    args: TemplateArgsType,
-) -> MockObj:
-    comp = await cg.get_variable(config[CONF_ID])
-    lambda_ = await cg.process_lambda(
-        Lambda(f"return {comp}->is_idle();"), args, return_type=bool
-    )
-    return new_lambda_pvariable(
-        condition_id, lambda_, StatelessLambdaCondition, template_arg
-    )
 
 
 @register_action(
@@ -534,44 +911,20 @@ async def lambda_action_to_code(
     return new_lambda_pvariable(action_id, lambda_, StatelessLambdaAction, template_arg)
 
 
-@register_action(
+register_simple_action(
     "component.update",
     UpdateComponentAction,
-    maybe_simple_id(
-        {
-            cv.Required(CONF_ID): cv.use_id(cg.PollingComponent),
-        }
-    ),
+    maybe_simple_id({cv.Required(CONF_ID): cv.use_id(cg.PollingComponent)}),
     synchronous=True,
 )
-async def component_update_action_to_code(
-    config: ConfigType,
-    action_id: ID,
-    template_arg: cg.TemplateArguments,
-    args: TemplateArgsType,
-) -> MockObj:
-    comp = await cg.get_variable(config[CONF_ID])
-    return cg.new_Pvariable(action_id, template_arg, comp)
 
 
-@register_action(
+register_simple_action(
     "component.suspend",
     SuspendComponentAction,
-    maybe_simple_id(
-        {
-            cv.Required(CONF_ID): cv.use_id(cg.PollingComponent),
-        }
-    ),
+    maybe_simple_id({cv.Required(CONF_ID): cv.use_id(cg.PollingComponent)}),
     synchronous=True,
 )
-async def component_suspend_action_to_code(
-    config: ConfigType,
-    action_id: ID,
-    template_arg: cg.TemplateArguments,
-    args: TemplateArgsType,
-) -> MockObj:
-    comp = await cg.get_variable(config[CONF_ID])
-    return cg.new_Pvariable(action_id, template_arg, comp)
 
 
 @register_action(

esphome/build_gen/build_tool.py

@@ -0,0 +1,108 @@
+"""Tiny cross-platform build steps invoked from the generated ninja file.
+
+Plain script (not ``python -m``): it runs from ninja with whatever Python
+started esphome and must not depend on the package being importable.
+
+Subcommands:
+    ar <ar-binary> <archive> <rspfile>   remove stale archive, then ``ar rcs``
+    copy <src> <dst>                     copy a file
+
+The ar rspfile carries one object path per line (the generating rule must
+use ``$in_newline``, never ``$in``).
+"""
+
+from pathlib import Path
+import shutil
+import subprocess
+import sys
+
+
+def _read_rspfile(rspfile: str) -> list[str]:
+    r"""The object paths listed in ``rspfile``, unquoted.
+
+    GNU ar treats backslashes in response files as escapes (corrupts
+    Windows paths), so the caller expands the list into argv; strip the
+    simple surrounding quote ninja adds to special paths, then undo
+    ninja's POSIX escape for an embedded quote ('a'\\''b.o' -> a'b.o).
+    """
+    return [
+        line[1:-1].replace("'\\''", "'")
+        if len(line) >= 2 and line[0] == line[-1] and line[0] in "'\""
+        else line
+        for line in Path(rspfile).read_text(encoding="utf-8").splitlines()
+        if line
+    ]
+
+
+def _run_ar(ar: str, archive: str, rspfile: str) -> int:
+    # Remove first: ``ar rcs`` replaces members but never drops ones whose
+    # source was removed from the build, which would leak stale objects.
+    Path(archive).unlink(missing_ok=True)
+    objects = _read_rspfile(rspfile)
+    if not objects:
+        # An empty archive would "succeed" here and fail far away at link
+        print(f"ar: no objects listed in {rspfile} for {archive}", file=sys.stderr)
+        return 1
+    # Batch by argv length: expanding the rspfile gives back the Windows
+    # 32767-char command-line limit it existed to avoid. "rcs" creates,
+    # "qs" appends; the s keeps the symbol index explicit on every ar.
+    op = "rcs"
+    ok = False
+    try:
+        while objects:
+            batch = [objects.pop(0)]
+            batch_len = len(batch[0])
+            while objects and batch_len + len(objects[0]) < 25000:
+                batch_len += len(objects[0]) + 1
+                batch.append(objects.pop(0))
+            rc = subprocess.run(
+                [ar, op, archive, *batch], check=False, close_fds=False
+            ).returncode
+            if rc != 0:
+                return rc
+            op = "qs"
+        ok = True
+        return 0
+    finally:
+        if not ok:
+            # Any failure (bad exit, missing ar binary, interrupt) must not
+            # leave a truncated archive behind
+            Path(archive).unlink(missing_ok=True)
+
+
+def _run_copy(src: str, dst: str) -> int:
+    try:
+        shutil.copyfile(src, dst)
+    except OSError as err:
+        # Never leave a partially written output (e.g. a firmware image);
+        # SameFileError means dst IS src, where unlinking destroys the input
+        if not isinstance(err, shutil.SameFileError):
+            Path(dst).unlink(missing_ok=True)
+        print(f"copy: {src} -> {dst} failed: {err}", file=sys.stderr)
+        return 1
+    return 0
+
+
+# mode -> (handler, expected operand count); surplus argv means a
+# mis-specified ninja rule and must error, not silently drop operands
+_MODES = {"ar": (_run_ar, 3), "copy": (_run_copy, 2)}
+
+
+def main() -> int:
+    mode = sys.argv[1] if len(sys.argv) > 1 else ""
+    if entry := _MODES.get(mode):
+        handler, argc = entry
+        args = sys.argv[2:]
+        if len(args) != argc:
+            print(
+                f"build_tool {mode}: expected {argc} arguments, got {len(args)}",
+                file=sys.stderr,
+            )
+            return 1
+        return handler(*args)
+    print(f"unknown build_tool mode: {mode}", file=sys.stderr)
+    return 1
+
+
+if __name__ == "__main__":  # pragma: no cover
+    sys.exit(main())

esphome/build_gen/espidf.py

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

esphome/build_helpers/__init__.py

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

esphome/build_helpers/ccache.py

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

esphome/build_helpers/idedata.py

@@ -0,0 +1,397 @@
+"""Derive idedata from a native (non-PlatformIO) build's ``compile_commands.json``.
+
+PlatformIO exposes a curated ``pio run -t idedata`` JSON; the native
+toolchains have no such command, but each build produces a
+``compile_commands.json`` (CMAKE_EXPORT_COMPILE_COMMANDS for ESP-IDF, ninja's
+compdb tool otherwise). This module turns that file into the same fields
+consumers (IDE integration, clang-tidy) expect:
+
+    {cc_path, cxx_path, cxx_flags, defines, includes: {build, toolchain}}
+"""
+
+from __future__ import annotations
+
+from collections.abc import Callable
+import json
+import logging
+import os
+from pathlib import Path
+import shlex
+import subprocess
+
+from esphome.core import EsphomeError
+from esphome.helpers import write_file
+
+_LOGGER = logging.getLogger(__name__)
+
+# Everything idedata generation may raise after a successful link; idedata
+# is a bonus artifact, so consumers warn instead of failing the build
+IDEDATA_BEST_EFFORT_ERRORS = (
+    EsphomeError,
+    LookupError,
+    OSError,
+    RuntimeError,
+    ValueError,
+)
+
+
+def warn_if_idedata_missing(get_idedata: Callable[[], dict | None]) -> None:
+    """Run an idedata generator, downgrading any failure to a warning:
+    the firmware already built."""
+    try:
+        if get_idedata() is None:
+            _LOGGER.warning("No idedata was generated for this build")
+    except IDEDATA_BEST_EFFORT_ERRORS as err:
+        _LOGGER.warning(
+            "Could not generate idedata: %s (IDE, clang-tidy, and "
+            "memory-analysis data will be unavailable for this build)",
+            err,
+        )
+        _LOGGER.debug("Idedata failure detail", exc_info=True)
+
+
+# C++ translation-unit suffixes used to identify ESPHome source files.
+_CXX_SUFFIXES = (".cpp", ".cc")
+# Suffixes of input/output files that appear bare on the command line (and so
+# must not be mistaken for compiler flags).
+_INPUT_FILE_SUFFIXES = (*_CXX_SUFFIXES, ".c", ".o", ".S", ".s")
+# Path marker identifying an ESPHome source translation unit.
+_ESPHOME_SRC_MARKER = "/src/esphome/"
+
+
+def _is_esphome_src(file: str) -> bool:
+    """Whether ``file`` is an ESPHome C++ translation unit; normalized to
+    ``/`` first since Windows compile DBs use backslashes."""
+    return _ESPHOME_SRC_MARKER in file.replace("\\", "/") and file.endswith(
+        _CXX_SUFFIXES
+    )
+
+
+def _split_command(command: str) -> list[str]:
+    r"""Tokenize a compile_commands.json / response-file command string.
+
+    On Windows, tokenize per Windows ``argv`` rules via ``CommandLineToArgvW``.
+    ESP-IDF's compile_commands.json there mixes two backslash conventions in one
+    string: literal path separators in the compiler path (``C:\Users\...g++.exe``,
+    no quote follows) and shell quote-escaping in -D defines (``-DVER=\"1.2.3\"``).
+    Only the real Windows parser — where a backslash escapes solely a following
+    quote — handles both, and it is the exact tokenizer the compiler is launched
+    with. ``shlex`` cannot: POSIX mode eats the path separators, and disabling
+    its escape mangles the defines.
+    """
+    if os.name != "nt":
+        return shlex.split(command)
+
+    import ctypes
+    from ctypes import wintypes
+
+    # CommandLineToArgvW("") returns the current process name, not []; guard it
+    # so an empty response file tokenizes the same as it would via shlex.
+    if not command.strip():
+        return []
+
+    CommandLineToArgvW = ctypes.windll.shell32.CommandLineToArgvW
+    CommandLineToArgvW.argtypes = [wintypes.LPCWSTR, ctypes.POINTER(ctypes.c_int)]
+    CommandLineToArgvW.restype = ctypes.POINTER(wintypes.LPWSTR)
+    argc = ctypes.c_int()
+    argv = CommandLineToArgvW(command, ctypes.byref(argc))
+    if not argv:  # pragma: no cover
+        raise ctypes.WinError()
+    try:
+        return [argv[i] for i in range(argc.value)]
+    finally:
+        ctypes.windll.kernel32.LocalFree(argv)
+
+
+def _expand_response_files(tokens: list[str], directory: Path) -> list[str]:
+    """Inline any ``@response-file`` arguments (paths relative to ``directory``).
+
+    GCC response files embed flags that must be expanded so GCC-only flags
+    inside them (e.g. ``-mlongcalls``) can be filtered downstream; left as
+    ``@file`` clang would read them and choke.
+    """
+    out: list[str] = []
+    for tok in tokens:
+        if tok.startswith("@"):
+            rf = Path(tok[1:])
+            if not rf.is_absolute():
+                rf = directory / rf
+            try:
+                out.extend(
+                    _expand_response_files(
+                        _split_command(rf.read_text(encoding="utf-8")), directory
+                    )
+                )
+                continue
+            except OSError as err:
+                # Keep the literal token if the file can't be read, but log it
+                # so the (otherwise opaque) downstream clang failure is traceable.
+                _LOGGER.warning("Could not read response file %s: %s", rf, err)
+        out.append(tok)
+    return out
+
+
+def _pick_entry(entries: list[dict]) -> dict:
+    """Pick a representative ESPHome C++ TU; all share the same component
+    flags/defines."""
+    for entry in entries:
+        if _is_esphome_src(entry["file"]):
+            return entry
+    for entry in entries:
+        if entry["file"].endswith(_CXX_SUFFIXES):
+            return entry
+    raise ValueError("no C++ translation unit found in compile_commands.json")
+
+
+# Compiler launchers that may prefix a compile command; a closed launcher
+# denylist beats enumerating compiler names, an open set.
+_LAUNCHER_STEMS = frozenset({"ccache", "sccache", "distcc", "icecc", "buildcache"})
+
+
+def _is_launcher(token: str) -> bool:
+    return Path(token).stem.lower() in _LAUNCHER_STEMS
+
+
+def parse_entry(
+    entry: dict, launcher: str | None = None
+) -> tuple[str, list[str], list[str], list[str]]:
+    """Parse one compile_commands entry -> (cxx_path, defines, includes, cxx_flags)."""
+    directory = Path(entry["directory"])
+    tokens = _expand_response_files(_split_command(entry["command"]), directory)
+
+    def _include(raw: str) -> str:
+        # Resolve against the entry's ``directory`` so cached idedata works
+        # from any cwd; emit forward slashes to match the JSON's own entries
+        raw = raw.strip()
+        if raw and not Path(raw).is_absolute():
+            raw = os.path.normpath(directory / raw)
+        return raw.replace("\\", "/")
+
+    # A launcher-wrapped command ("ccache g++ ...") names the compiler second
+    if launcher is not None and tokens[:1] == [launcher]:
+        tokens = tokens[1:]
+    if not tokens:
+        # An empty command, or one that was only the launcher; fail by name
+        raise ValueError(f"empty compile command for {entry.get('file')}")
+    if _is_launcher(tokens[0]) and len(tokens) > 1 and not tokens[1].startswith("-"):
+        # Stale DB built with a launcher this run no longer configures; the
+        # real compiler is the next token
+        _LOGGER.warning("Stripping unconfigured launcher %s", tokens[0])
+        tokens = tokens[1:]
+    # token0 is the compiler path; the rest of the command already uses forward
+    # slashes on Windows, so normalize it too for a consistent idedata file.
+    cxx_path = tokens[0].replace("\\", "/")
+    # Enforced here so no caller can record ccache as the compiler
+    reject_launcher_compiler(cxx_path)
+    defines: list[str] = []
+    includes: list[str] = []
+    cxx_flags: list[str] = []
+
+    it = iter(tokens[1:])
+    for tok in it:
+        if tok in ("-c", "-o"):
+            next(it, None)  # drop the flag and its argument (input/output)
+        elif tok.startswith("-D"):
+            # ``.strip()`` handles tokens like ``-D CONFIGURED=1`` (a single
+            # quoted arg with a space after -D) that some flags arrive as.
+            defines.append(tok[2:].strip() if len(tok) > 2 else next(it, "").strip())
+        elif tok.startswith("-I"):
+            includes.append(_include(tok[2:] if len(tok) > 2 else next(it, "")))
+        elif tok == "-isystem":
+            includes.append(_include(next(it, "")))
+        elif tok.startswith("-isystem"):
+            includes.append(_include(tok[len("-isystem") :]))
+        elif tok in ("-MT", "-MF", "-MQ"):
+            next(it, None)  # dependency-file flag + its argument
+        elif tok.startswith(("-MD", "-MMD", "-MP", "-MM")):
+            pass  # dependency-generation flags, no argument
+        elif tok.endswith(_INPUT_FILE_SUFFIXES):
+            pass  # input/output files
+        else:
+            cxx_flags.append(tok)
+    return cxx_path, defines, includes, cxx_flags
+
+
+def get_toolchain_includes(cxx_path: str) -> list[str]:
+    """Query the compiler for its builtin ``#include <...>`` search dirs."""
+    result = subprocess.run(
+        [cxx_path, "-E", "-x", "c++", "-", "-v"],
+        input="",
+        text=True,
+        stdout=subprocess.DEVNULL,
+        stderr=subprocess.PIPE,
+        check=False,
+        close_fds=False,
+    )
+    includes: list[str] = []
+    capture = False
+    for line in result.stderr.splitlines():
+        if "#include <...> search starts here:" in line:
+            capture = True
+            continue
+        if "End of search list." in line:
+            break
+        if capture:
+            includes.append(line.strip())
+    if result.returncode != 0 or not includes:
+        raise RuntimeError(
+            f"Could not query builtin include dirs from {cxx_path} "
+            f"(return code {result.returncode}); stderr:\n{result.stderr.strip()}"
+        )
+    return includes
+
+
+def _cc_path_from_cxx(cxx_path: str) -> str:
+    """Derive the C compiler path from the C++ compiler path.
+
+    compile_commands.json only names the C++ compiler, but consumers reach the
+    rest of the toolchain (objdump, readelf, addr2line) by rewriting the tail of
+    ``cc_path``, so they need the ``gcc``-suffixed name.
+    """
+    stem, suffix = (
+        (cxx_path[: -len(".exe")], ".exe")
+        if cxx_path.endswith(".exe")
+        else (cxx_path, "")
+    )
+    # Rewrite the program name only when it is g++ itself, or a toolchain
+    # prefixed one such as xtensa-esp32-elf-g++ -> xtensa-esp32-elf-gcc.
+    # Requiring a separator before the "g++" keeps names that merely end in
+    # those three characters intact: "clang++" must not become "clangcc".
+    head = stem[: -len("g++")]
+    if stem.endswith("g++") and (not head or head.endswith(("-", "/", "\\"))):
+        stem = f"{head}gcc"
+    return f"{stem}{suffix}"
+
+
+def _cache_usable(cached: object) -> bool:
+    """Check a cached idedata dict against the guarantees of the write path.
+
+    Caches written by older versions predate the launcher rejection and the
+    include-union shape; serving one would bypass both. The dict check also
+    keeps "in" from substring-matching a bare JSON string.
+    """
+    if not isinstance(cached, dict) or "cc_path" not in cached:
+        return False
+    cxx_path = cached.get("cxx_path")
+    if not isinstance(cxx_path, str) or _is_launcher(cxx_path):
+        return False
+    includes = cached.get("includes")
+    return isinstance(includes, dict) and isinstance(includes.get("build"), list)
+
+
+def load_or_build_idedata(
+    compile_commands: Path,
+    elf_path: Path,
+    cache: Path,
+    launcher: str | None = None,
+) -> dict | None:
+    """Return idedata for a compile_commands.json build, cached on mtime.
+
+    Shared by the native ESP-IDF and ESP8266 Arduino toolchains. Returns None
+    when the compile DB doesn't exist yet (nothing was built). ``launcher``
+    is the compiler-launcher path (ccache) the build was generated with, if
+    any; commands in the compile DB are prefixed with it.
+    """
+    if not compile_commands.is_file():
+        _LOGGER.debug("No %s yet; skipping idedata generation", compile_commands)
+        return None
+
+    if cache.is_file() and cache.stat().st_mtime >= compile_commands.stat().st_mtime:
+        try:
+            cached = json.loads(cache.read_text(encoding="utf-8"))
+        except (ValueError, OSError) as err:
+            # A recurring cause (interrupted write, disk full) would otherwise
+            # look like unexplained slow builds
+            _LOGGER.warning("Discarding unreadable idedata cache %s: %s", cache, err)
+        else:
+            if _cache_usable(cached):
+                # Re-stamp so a relocated build dir cannot serve a stale ELF path
+                cached["prog_path"] = str(elf_path)
+                return cached
+            _LOGGER.debug("Regenerating idedata: cache %s fails validation", cache)
+
+    data = idedata_from_build(compile_commands, launcher)
+    data["prog_path"] = str(elf_path)
+    cache.parent.mkdir(parents=True, exist_ok=True)
+    # Atomic so a crash mid-write cannot leave a truncated cache
+    write_file(cache, json.dumps(data, indent=2) + "\n")
+    return data
+
+
+def reject_launcher_compiler(cxx_path: str) -> None:
+    """Reject a compile DB naming a launcher (ccache) as the compiler; it
+    must never be probed, cached, or consumed."""
+    if _is_launcher(cxx_path):
+        raise EsphomeError(
+            f"compile_commands.json names the launcher {cxx_path} as the "
+            "compiler; the compile database is unusable"
+        )
+
+
+def idedata_from_build(compile_commands: Path, launcher: str | None = None) -> dict:
+    """Parse compile_commands.json into the idedata fields consumers expect.
+
+    A single compile entry only carries the include set its own translation
+    unit was built with (per-component under ESP-IDF), but consumers
+    (clang-tidy) analyze ESPHome headers that transitively pull in other
+    components. So take cxx_path / cxx_flags / defines from a representative
+    ESPHome TU, but union the include dirs across all ESPHome TUs to get a
+    project-wide superset (as PlatformIO's idedata provides).
+    """
+    entries = json.loads(Path(compile_commands).read_text(encoding="utf-8"))
+    if not isinstance(entries, list) or not all(isinstance(e, dict) for e in entries):
+        # A TypeError here would escape IDEDATA_BEST_EFFORT_ERRORS
+        raise EsphomeError(f"{compile_commands} is not a compile-command list")
+
+    representative = _pick_entry(entries)
+    cxx_path, defines, rep_includes, cxx_flags = parse_entry(representative, launcher)
+
+    # Seed with the representative's includes so it is not parsed twice
+    has_esphome_tu = _is_esphome_src(representative["file"])
+    build_includes: dict[str, None] = dict.fromkeys(
+        rep_includes if has_esphome_tu else ()
+    )
+
+    def _shape(entry: dict) -> str:
+        # directory + command minus TU-specific paths: same shape means the
+        # same include set, so tokenize once per shape. Response-file
+        # commands never dedupe (the .rsp contents differ per object)
+        command = entry["command"]
+        directory = entry.get("directory", "")
+        if "@" in command:
+            return f"unique:{directory}|{entry.get('output') or command}"
+        stripped = command.replace(entry.get("file", ""), "").replace(
+            entry.get("output", ""), ""
+        )
+        return f"{directory}|{stripped}"
+
+    seen_shapes = {_shape(representative)}
+    for entry in entries:
+        if entry is representative or not _is_esphome_src(entry["file"]):
+            continue
+        has_esphome_tu = True
+        if (shape := _shape(entry)) in seen_shapes:
+            _LOGGER.debug("Include union: %s shares a command shape", entry["file"])
+            continue
+        seen_shapes.add(shape)
+        for inc in parse_entry(entry, launcher)[2]:
+            build_includes.setdefault(inc, None)
+
+    if not has_esphome_tu:
+        # An arbitrary fallback TU breaks clang-tidy/IDE consumers, and a
+        # warning would be cached into permanence; call sites downgrade this
+        raise EsphomeError(
+            f"No ESPHome translation unit found in {compile_commands}; "
+            "refusing to cache unusable idedata"
+        )
+
+    return {
+        "cc_path": _cc_path_from_cxx(cxx_path),
+        "cxx_path": cxx_path,
+        "cxx_flags": cxx_flags,
+        "defines": defines,
+        "includes": {
+            "build": list(build_includes),
+            "toolchain": get_toolchain_includes(cxx_path),
+        },
+    }

esphome/build_helpers/native.py

@@ -0,0 +1,52 @@
+"""Resolution of the native (non-PlatformIO) build backend for a config.
+
+Kept deliberately light: the serial upload and logs fast path resolves a
+backend for its artifact paths alone, so importing this must not pull in a
+platform component package or the backend itself.
+"""
+
+from __future__ import annotations
+
+import importlib
+from types import ModuleType
+
+from esphome.const import Toolchain
+from esphome.core import CORE, EsphomeError
+
+# Native build backend per (target platform, toolchain)
+NATIVE_TOOLCHAIN_MODULES = {
+    ("esp32", Toolchain.ESP_IDF): "esphome.espidf.toolchain",
+    ("esp8266", Toolchain.ARDUINO): "esphome.arduino8266.toolchain",
+}
+
+
+def native_backend() -> ModuleType | None:
+    """The native build backend module for the resolved toolchain."""
+    if not CORE.using_native_toolchain:
+        return None
+    key = (CORE.target_platform, CORE.toolchain)
+    if (module_path := NATIVE_TOOLCHAIN_MODULES.get(key)) is None:
+        # Degrading to the PlatformIO path would build with the wrong backend
+        raise EsphomeError(
+            f"Toolchain '{CORE.toolchain.value}' has no native build backend "
+            f"module for platform {CORE.target_platform}"
+        )
+    return importlib.import_module(module_path)
+
+
+# Binutils and the linked image for memory analysis, for toolchains that build
+# without PlatformIO but have no native build backend (which supplies them)
+ANALYSIS_TOOLCHAIN_MODULES = {
+    ("nrf52", Toolchain.SDK_NRF): "esphome.components.nrf52.toolchain",
+}
+
+
+def analysis_backend() -> ModuleType | None:
+    """The module giving objdump, readelf and the ELF of a non-PlatformIO build.
+
+    None means PlatformIO's idedata supplies them (or nothing can).
+    """
+    if (native := native_backend()) is not None:
+        return native
+    module_path = ANALYSIS_TOOLCHAIN_MODULES.get((CORE.target_platform, CORE.toolchain))
+    return importlib.import_module(module_path) if module_path else None

esphome/build_helpers/ninja.py

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

esphome/build_helpers/size_summary.py

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

esphome/build_helpers/tools_cache.py

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

esphome/codegen.py

@@ -64,7 +64,6 @@ from esphome.cpp_types import (  # noqa: F401
     Application,
     Component,
     ComponentPtr,
-    Controller,
     EntityBase,
     EntityCategory,
     ESPTime,
@@ -78,6 +77,7 @@ from esphome.cpp_types import (  # noqa: F401
     StringRef,
     arduino_json_ns,
     bool_,
+    char,
     const_char_ptr,
     double,
     esphome_ns,

esphome/compiled_config.py

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

esphome/component_aliases.py

@@ -6,5 +6,6 @@ See the component-alias section of esphome/loader.py.
 
 # alias -> (canonical component, removal version or None)
 COMPONENT_ALIASES: dict[str, tuple[str, str | None]] = {
+    "esp32_improv": ("improv_ble", "2027.4.0"),
     "rp2040": ("rp2", "2027.7.0"),
 }

esphome/components/adc/__init__.py

@@ -13,6 +13,7 @@ from esphome.components.esp32 import (
     VARIANT_ESP32P4,
     VARIANT_ESP32S2,
     VARIANT_ESP32S3,
+    VARIANT_ESP32S31,
     get_esp32_variant,
 )
 import esphome.config_validation as cv
@@ -156,6 +157,17 @@ ESP32_VARIANT_ADC1_PIN_TO_CHANNEL = {
         9: adc_channel_t.ADC_CHANNEL_8,
         10: adc_channel_t.ADC_CHANNEL_9,
     },
+    # https://github.com/espressif/esp-idf/blob/master/components/soc/esp32s31/include/soc/adc_channel.h
+    VARIANT_ESP32S31: {
+        42: adc_channel_t.ADC_CHANNEL_0,
+        43: adc_channel_t.ADC_CHANNEL_1,
+        44: adc_channel_t.ADC_CHANNEL_2,
+        45: adc_channel_t.ADC_CHANNEL_3,
+        46: adc_channel_t.ADC_CHANNEL_4,
+        47: adc_channel_t.ADC_CHANNEL_5,
+        48: adc_channel_t.ADC_CHANNEL_6,
+        49: adc_channel_t.ADC_CHANNEL_7,
+    },
 }
 
 # pin to adc2 channel mapping
@@ -225,6 +237,17 @@ ESP32_VARIANT_ADC2_PIN_TO_CHANNEL = {
         19: adc_channel_t.ADC_CHANNEL_8,
         20: adc_channel_t.ADC_CHANNEL_9,
     },
+    # https://github.com/espressif/esp-idf/blob/master/components/soc/esp32s31/include/soc/adc_channel.h
+    VARIANT_ESP32S31: {
+        50: adc_channel_t.ADC_CHANNEL_0,
+        51: adc_channel_t.ADC_CHANNEL_1,
+        52: adc_channel_t.ADC_CHANNEL_2,
+        53: adc_channel_t.ADC_CHANNEL_3,
+        54: adc_channel_t.ADC_CHANNEL_4,
+        55: adc_channel_t.ADC_CHANNEL_5,
+        56: adc_channel_t.ADC_CHANNEL_6,
+        57: adc_channel_t.ADC_CHANNEL_7,
+    },
 }
 
 

esphome/components/adc/adc_sensor.h

@@ -94,7 +94,7 @@ class ADCSensor final : public sensor::Sensor, public PollingComponent, public v
   ///   - SamplingMode::MIN: Use the lowest sample value
   ///   - SamplingMode::MAX: Use the highest sample value
   /// @param sampling_mode The desired sampling mode to use for aggregating ADC samples.
-  void set_sampling_mode(SamplingMode sampling_mode);
+  void set_sampling_mode(SamplingMode sampling_mode) { this->sampling_mode_ = sampling_mode; }
 
   /// Perform a single ADC sampling operation and return the measured value.
   /// This function handles raw readings, calibration, and averaging as needed.

esphome/components/adc/adc_sensor_common.cpp

@@ -76,6 +76,4 @@ void ADCSensor::set_sample_count(uint8_t sample_count) {
   }
 }
 
-void ADCSensor::set_sampling_mode(SamplingMode sampling_mode) { this->sampling_mode_ = sampling_mode; }
-
 }  // namespace esphome::adc

esphome/components/adc/adc_sensor_esp32.cpp

@@ -74,9 +74,7 @@ void ADCSensor::setup() {
   if (this->calibration_handle_ == nullptr) {
     adc_cali_handle_t handle = nullptr;
 
-#if USE_ESP32_VARIANT_ESP32C3 || USE_ESP32_VARIANT_ESP32C5 || USE_ESP32_VARIANT_ESP32C6 || \
-    USE_ESP32_VARIANT_ESP32C61 || USE_ESP32_VARIANT_ESP32H2 || USE_ESP32_VARIANT_ESP32P4 || USE_ESP32_VARIANT_ESP32S3
-    // RISC-V variants (except C2) and S3 use curve fitting calibration
+#if defined(ADC_CALI_SCHEME_CURVE_FITTING_SUPPORTED)
     adc_cali_curve_fitting_config_t cali_config = {};  // Zero initialize first
 #if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(5, 3, 0)
     cali_config.chan = this->channel_;
@@ -94,7 +92,7 @@ void ADCSensor::setup() {
       ESP_LOGW(TAG, "Curve fitting calibration failed with error %d, will use uncalibrated readings", err);
       this->setup_flags_.calibration_complete = false;
     }
-#else  // ESP32, ESP32-S2, and ESP32-C2 use line fitting calibration
+#elif defined(ADC_CALI_SCHEME_LINE_FITTING_SUPPORTED)
     adc_cali_line_fitting_config_t cali_config = {
       .unit_id = this->adc_unit_,
       .atten = this->attenuation_,
@@ -112,7 +110,11 @@ void ADCSensor::setup() {
       ESP_LOGW(TAG, "Line fitting calibration failed with error %d, will use uncalibrated readings", err);
       this->setup_flags_.calibration_complete = false;
     }
-#endif  // ESP32C3 || ESP32C5 || ESP32C6 || ESP32C61 || ESP32H2 || ESP32P4 || ESP32S3
+#else   // No calibration scheme available
+    (void) handle;
+    ESP_LOGD(TAG, "No calibration scheme for this variant, readings are uncalibrated");
+    this->setup_flags_.calibration_complete = false;
+#endif
   }
 
   this->setup_flags_.init_complete = true;
@@ -121,23 +123,28 @@ void ADCSensor::setup() {
 void ADCSensor::dump_config() {
   LOG_SENSOR("", "ADC Sensor", this);
   LOG_PIN("  Pin: ", this->pin_);
-  ESP_LOGCONFIG(
-      TAG,
-      "  Channel:       %d\n"
-      "  Unit:          %s\n"
-      "  Attenuation:   %s\n"
-      "  Samples:       %i\n"
-      "  Sampling mode: %s\n"
-      "  Setup Status:\n"
-      "    Handle Init:  %s\n"
-      "    Config:       %s\n"
-      "    Calibration:  %s\n"
-      "    Overall Init: %s",
-      this->channel_, LOG_STR_ARG(adc_unit_to_str(this->adc_unit_)),
-      this->autorange_ ? "Auto" : LOG_STR_ARG(attenuation_to_str(this->attenuation_)), this->sample_count_,
-      LOG_STR_ARG(sampling_mode_to_str(this->sampling_mode_)),
-      this->setup_flags_.handle_init_complete ? "OK" : "FAILED", this->setup_flags_.config_complete ? "OK" : "FAILED",
-      this->setup_flags_.calibration_complete ? "OK" : "FAILED", this->setup_flags_.init_complete ? "OK" : "FAILED");
+#if defined(ADC_CALI_SCHEME_CURVE_FITTING_SUPPORTED) || defined(ADC_CALI_SCHEME_LINE_FITTING_SUPPORTED)
+  const char *calibration_status = this->setup_flags_.calibration_complete ? "OK" : "FAILED";
+#else
+  const char *calibration_status = "N/A";  // This variant has no calibration scheme
+#endif
+  ESP_LOGCONFIG(TAG,
+                "  Channel:       %d\n"
+                "  Unit:          %s\n"
+                "  Attenuation:   %s\n"
+                "  Samples:       %i\n"
+                "  Sampling mode: %s\n"
+                "  Setup Status:\n"
+                "    Handle Init:  %s\n"
+                "    Config:       %s\n"
+                "    Calibration:  %s\n"
+                "    Overall Init: %s",
+                this->channel_, LOG_STR_ARG(adc_unit_to_str(this->adc_unit_)),
+                this->autorange_ ? "Auto" : LOG_STR_ARG(attenuation_to_str(this->attenuation_)), this->sample_count_,
+                LOG_STR_ARG(sampling_mode_to_str(this->sampling_mode_)),
+                this->setup_flags_.handle_init_complete ? "OK" : "FAILED",
+                this->setup_flags_.config_complete ? "OK" : "FAILED", calibration_status,
+                this->setup_flags_.init_complete ? "OK" : "FAILED");
 
   LOG_UPDATE_INTERVAL(this);
 }
@@ -184,12 +191,11 @@ float ADCSensor::sample_fixed_attenuation_() {
     } else {
       ESP_LOGW(TAG, "ADC calibration conversion failed with error %d, disabling calibration", err);
       if (this->calibration_handle_ != nullptr) {
-#if USE_ESP32_VARIANT_ESP32C3 || USE_ESP32_VARIANT_ESP32C5 || USE_ESP32_VARIANT_ESP32C6 || \
-    USE_ESP32_VARIANT_ESP32C61 || USE_ESP32_VARIANT_ESP32H2 || USE_ESP32_VARIANT_ESP32P4 || USE_ESP32_VARIANT_ESP32S3
+#if defined(ADC_CALI_SCHEME_CURVE_FITTING_SUPPORTED)
         adc_cali_delete_scheme_curve_fitting(this->calibration_handle_);
-#else   // Other ESP32 variants use line fitting calibration
+#elif defined(ADC_CALI_SCHEME_LINE_FITTING_SUPPORTED)
         adc_cali_delete_scheme_line_fitting(this->calibration_handle_);
-#endif  // ESP32C3 || ESP32C5 || ESP32C6 || ESP32C61 || ESP32H2 || ESP32P4 || ESP32S3
+#endif
         this->calibration_handle_ = nullptr;
       }
     }
@@ -217,10 +223,9 @@ float ADCSensor::sample_autorange_() {
     // Need to recalibrate for the new attenuation
     if (this->calibration_handle_ != nullptr) {
       // Delete old calibration handle
-#if USE_ESP32_VARIANT_ESP32C3 || USE_ESP32_VARIANT_ESP32C5 || USE_ESP32_VARIANT_ESP32C6 || \
-    USE_ESP32_VARIANT_ESP32C61 || USE_ESP32_VARIANT_ESP32H2 || USE_ESP32_VARIANT_ESP32P4 || USE_ESP32_VARIANT_ESP32S3
+#if defined(ADC_CALI_SCHEME_CURVE_FITTING_SUPPORTED)
       adc_cali_delete_scheme_curve_fitting(this->calibration_handle_);
-#else
+#elif defined(ADC_CALI_SCHEME_LINE_FITTING_SUPPORTED)
       adc_cali_delete_scheme_line_fitting(this->calibration_handle_);
 #endif
       this->calibration_handle_ = nullptr;
@@ -229,8 +234,7 @@ float ADCSensor::sample_autorange_() {
     // Create new calibration handle for this attenuation
     adc_cali_handle_t handle = nullptr;
 
-#if USE_ESP32_VARIANT_ESP32C3 || USE_ESP32_VARIANT_ESP32C5 || USE_ESP32_VARIANT_ESP32C6 || \
-    USE_ESP32_VARIANT_ESP32C61 || USE_ESP32_VARIANT_ESP32H2 || USE_ESP32_VARIANT_ESP32P4 || USE_ESP32_VARIANT_ESP32S3
+#if defined(ADC_CALI_SCHEME_CURVE_FITTING_SUPPORTED)
     adc_cali_curve_fitting_config_t cali_config = {};
 #if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(5, 3, 0)
     cali_config.chan = this->channel_;
@@ -242,7 +246,7 @@ float ADCSensor::sample_autorange_() {
     err = adc_cali_create_scheme_curve_fitting(&cali_config, &handle);
     ESP_LOGVV(TAG, "Autorange atten=%d: Calibration handle creation %s (err=%d)", atten,
               (err == ESP_OK) ? "SUCCESS" : "FAILED", err);
-#else
+#elif defined(ADC_CALI_SCHEME_LINE_FITTING_SUPPORTED)
     adc_cali_line_fitting_config_t cali_config = {
       .unit_id = this->adc_unit_,
       .atten = atten,
@@ -264,10 +268,9 @@ float ADCSensor::sample_autorange_() {
     if (err != ESP_OK) {
       ESP_LOGW(TAG, "ADC read failed in autorange with error %d", err);
       if (handle != nullptr) {
-#if USE_ESP32_VARIANT_ESP32C3 || USE_ESP32_VARIANT_ESP32C5 || USE_ESP32_VARIANT_ESP32C6 || \
-    USE_ESP32_VARIANT_ESP32C61 || USE_ESP32_VARIANT_ESP32H2 || USE_ESP32_VARIANT_ESP32P4 || USE_ESP32_VARIANT_ESP32S3
+#if defined(ADC_CALI_SCHEME_CURVE_FITTING_SUPPORTED)
         adc_cali_delete_scheme_curve_fitting(handle);
-#else
+#elif defined(ADC_CALI_SCHEME_LINE_FITTING_SUPPORTED)
         adc_cali_delete_scheme_line_fitting(handle);
 #endif
       }
@@ -286,10 +289,9 @@ float ADCSensor::sample_autorange_() {
         ESP_LOGVV(TAG, "Autorange atten=%d: UNCALIBRATED FALLBACK - raw=%d -> %.6fV (3.3V ref)", atten, raw, voltage);
       }
       // Clean up calibration handle
-#if USE_ESP32_VARIANT_ESP32C3 || USE_ESP32_VARIANT_ESP32C5 || USE_ESP32_VARIANT_ESP32C6 || \
-    USE_ESP32_VARIANT_ESP32C61 || USE_ESP32_VARIANT_ESP32H2 || USE_ESP32_VARIANT_ESP32P4 || USE_ESP32_VARIANT_ESP32S3
+#if defined(ADC_CALI_SCHEME_CURVE_FITTING_SUPPORTED)
       adc_cali_delete_scheme_curve_fitting(handle);
-#else
+#elif defined(ADC_CALI_SCHEME_LINE_FITTING_SUPPORTED)
       adc_cali_delete_scheme_line_fitting(handle);
 #endif
     } else {

esphome/components/adc/sensor.py

@@ -3,6 +3,7 @@ import logging
 import esphome.codegen as cg
 from esphome.components import sensor, voltage_sampler
 from esphome.components.esp32 import (
+    VARIANT_ESP32S31,
     get_esp32_variant,
     include_builtin_idf_component,
     require_adc_oneshot_iram,
@@ -56,6 +57,14 @@ def validate_config(config: ConfigType) -> ConfigType:
     if config[CONF_RAW] and config.get(CONF_ATTENUATION, None) == "auto":
         raise cv.Invalid("Automatic attenuation cannot be used when raw output is set")
 
+    # The S31 ADC supports a single attenuation level (SOC_ADC_ATTEN_NUM is 1)
+    if (
+        CORE.is_esp32
+        and get_esp32_variant() == VARIANT_ESP32S31
+        and config.get(CONF_ATTENUATION, "0db") != "0db"
+    ):
+        raise cv.Invalid("ESP32-S31 only supports 'attenuation: 0db'")
+
     if config.get(CONF_ATTENUATION, None) == "auto" and config.get(CONF_SAMPLES, 1) > 1:
         raise cv.Invalid(
             "Automatic attenuation cannot be used when multisampling is set"

esphome/components/ags10/ags10.cpp

@@ -106,6 +106,20 @@ bool AGS10Component::set_zero_point_with_factory_defaults() { return this->set_z
 
 bool AGS10Component::set_zero_point_with_current_resistance() { return this->set_zero_point_with(ZP_CURRENT); }
 
+void AGS10Component::set_zero_point(AGS10SetZeroPointActionMode mode, uint16_t value) {
+  switch (mode) {
+    case FACTORY_DEFAULT:
+      this->set_zero_point_with_factory_defaults();
+      break;
+    case CURRENT_VALUE:
+      this->set_zero_point_with_current_resistance();
+      break;
+    case CUSTOM_VALUE:
+      this->set_zero_point_with(value);
+      break;
+  }
+}
+
 bool AGS10Component::set_zero_point_with(uint16_t value) {
   std::array<uint8_t, 5> data{0x00, 0x0C, (uint8_t) ((value >> 8) & 0xFF), (uint8_t) (value & 0xFF), 0};
   data[4] = crc8(data.data(), 4, 0xFF, 0x31, true);

esphome/components/ags10/ags10.h

@@ -2,11 +2,19 @@
 
 #include "esphome/components/i2c/i2c.h"
 #include "esphome/components/sensor/sensor.h"
-#include "esphome/core/automation.h"
 #include "esphome/core/component.h"
 
 namespace esphome::ags10 {
 
+enum AGS10SetZeroPointActionMode {
+  // Zero-point reset.
+  FACTORY_DEFAULT,
+  // Zero-point calibration with current resistance.
+  CURRENT_VALUE,
+  // Zero-point calibration with custom resistance.
+  CUSTOM_VALUE,
+};
+
 class AGS10Component final : public PollingComponent, public i2c::I2CDevice {
  public:
   /**
@@ -47,6 +55,11 @@ class AGS10Component final : public PollingComponent, public i2c::I2CDevice {
    */
   bool set_zero_point_with_current_resistance();
 
+  /**
+   * Sets zero-point by mode; the value is only used for CUSTOM_VALUE.
+   */
+  void set_zero_point(AGS10SetZeroPointActionMode mode, uint16_t value);
+
   /**
    * Sets zero-point with the value.
    */
@@ -100,39 +113,4 @@ class AGS10Component final : public PollingComponent, public i2c::I2CDevice {
   template<size_t N> optional<std::array<uint8_t, N>> read_and_check_(uint8_t a_register);
 };
 
-template<typename... Ts> class AGS10NewI2cAddressAction final : public Action<Ts...>, public Parented<AGS10Component> {
- public:
-  TEMPLATABLE_VALUE(uint8_t, new_address)
-
-  void play(const Ts &...x) override { this->parent_->new_i2c_address(this->new_address_.value(x...)); }
-};
-
-enum AGS10SetZeroPointActionMode {
-  // Zero-point reset.
-  FACTORY_DEFAULT,
-  // Zero-point calibration with current resistance.
-  CURRENT_VALUE,
-  // Zero-point calibration with custom resistance.
-  CUSTOM_VALUE,
-};
-
-template<typename... Ts> class AGS10SetZeroPointAction final : public Action<Ts...>, public Parented<AGS10Component> {
- public:
-  TEMPLATABLE_VALUE(uint16_t, value)
-  TEMPLATABLE_VALUE(AGS10SetZeroPointActionMode, mode)
-
-  void play(const Ts &...x) override {
-    switch (this->mode_.value(x...)) {
-      case FACTORY_DEFAULT:
-        this->parent_->set_zero_point_with_factory_defaults();
-        break;
-      case CURRENT_VALUE:
-        this->parent_->set_zero_point_with_current_resistance();
-        break;
-      case CUSTOM_VALUE:
-        this->parent_->set_zero_point_with(this->value_.value(x...));
-        break;
-    }
-  }
-};
 }  // namespace esphome::ags10

esphome/components/ags10/sensor.py

@@ -17,8 +17,6 @@ from esphome.const import (
     UNIT_OHM,
     UNIT_PARTS_PER_BILLION,
 )
-from esphome.core import ID
-from esphome.cpp_generator import MockObj, TemplateArgsType
 from esphome.types import ConfigType
 
 CONF_RESISTANCE = "resistance"
@@ -28,12 +26,6 @@ DEPENDENCIES = ["i2c"]
 ags10_ns = cg.esphome_ns.namespace("ags10")
 AGS10Component = ags10_ns.class_("AGS10Component", cg.PollingComponent, i2c.I2CDevice)
 
-# Actions
-AGS10NewI2cAddressAction = ags10_ns.class_(
-    "AGS10NewI2cAddressAction", automation.Action
-)
-AGS10SetZeroPointAction = ags10_ns.class_("AGS10SetZeroPointAction", automation.Action)
-
 CONFIG_SCHEMA = (
     cv.Schema(
         {
@@ -91,24 +83,11 @@ AGS10_NEW_I2C_ADDRESS_SCHEMA = cv.maybe_simple_value(
 )
 
 
-@automation.register_action(
+automation.register_apply_action(
     "ags10.new_i2c_address",
-    AGS10NewI2cAddressAction,
     AGS10_NEW_I2C_ADDRESS_SCHEMA,
-    synchronous=True,
+    automation.ApplyField(CONF_ADDRESS, "new_i2c_address", cg.uint8),
 )
-async def ags10newi2caddress_to_code(
-    config: ConfigType,
-    action_id: ID,
-    template_arg: cg.TemplateArguments,
-    args: TemplateArgsType,
-) -> MockObj:
-    var = cg.new_Pvariable(action_id, template_arg)
-    await cg.register_parented(var, config[CONF_ID])
-    address = await cg.templatable(config[CONF_ADDRESS], args, cg.uint8)
-    cg.add(var.set_new_address(address))
-    return var
-
 
 AGS10SetZeroPointActionMode = ags10_ns.enum("AGS10SetZeroPointActionMode")
 AGS10_SET_ZERO_POINT_ACTION_MODE = {
@@ -128,24 +107,11 @@ AGS10_SET_ZERO_POINT_SCHEMA = cv.Schema(
 )
 
 
-@automation.register_action(
+automation.register_apply_action(
     "ags10.set_zero_point",
-    AGS10SetZeroPointAction,
     AGS10_SET_ZERO_POINT_SCHEMA,
-    synchronous=True,
+    automation.ApplyCall(
+        "set_zero_point({}, {})",
+        ((CONF_MODE, AGS10SetZeroPointActionMode), (CONF_VALUE, cg.uint16)),
+    ),
 )
-async def ags10setzeropoint_to_code(
-    config: ConfigType,
-    action_id: ID,
-    template_arg: cg.TemplateArguments,
-    args: TemplateArgsType,
-) -> MockObj:
-    var = cg.new_Pvariable(action_id, template_arg)
-    await cg.register_parented(var, config[CONF_ID])
-    mode = await cg.templatable(
-        config.get(CONF_MODE), args, AGS10SetZeroPointActionMode
-    )
-    cg.add(var.set_mode(mode))
-    value = await cg.templatable(config[CONF_VALUE], args, cg.uint16)
-    cg.add(var.set_value(value))
-    return var

esphome/components/aic3204/audio_dac.py

@@ -4,8 +4,6 @@ from esphome.components import i2c
 from esphome.components.audio_dac import AudioDac
 import esphome.config_validation as cv
 from esphome.const import CONF_ID, CONF_MODE
-from esphome.core import ID
-from esphome.cpp_generator import MockObj, TemplateArgsType
 from esphome.types import ConfigType
 
 CODEOWNERS = ["@kbx81"]
@@ -14,7 +12,6 @@ DEPENDENCIES = ["i2c"]
 aic3204_ns = cg.esphome_ns.namespace("aic3204")
 AIC3204 = aic3204_ns.class_("AIC3204", AudioDac, cg.Component, i2c.I2CDevice)
 
-SetAutoMuteAction = aic3204_ns.class_("SetAutoMuteAction", automation.Action)
 
 CONFIG_SCHEMA = (
     cv.Schema(
@@ -36,25 +33,11 @@ SET_AUTO_MUTE_ACTION_SCHEMA = cv.maybe_simple_value(
 )
 
 
-@automation.register_action(
+automation.register_apply_action(
     "aic3204.set_auto_mute_mode",
-    SetAutoMuteAction,
     SET_AUTO_MUTE_ACTION_SCHEMA,
-    synchronous=True,
+    automation.ApplyField(CONF_MODE, "set_auto_mute_mode", cg.uint8),
 )
-async def aic3204_set_volume_to_code(
-    config: ConfigType,
-    action_id: ID,
-    template_arg: cg.TemplateArguments,
-    args: TemplateArgsType,
-) -> MockObj:
-    paren = await cg.get_variable(config[CONF_ID])
-    var = cg.new_Pvariable(action_id, template_arg, paren)
-
-    template_ = await cg.templatable(config.get(CONF_MODE), args, cg.uint8)
-    cg.add(var.set_auto_mute_mode(template_))
-
-    return var
 
 
 async def to_code(config: ConfigType) -> None:

esphome/components/aic3204/automation.h

@@ -1,21 +0,0 @@
-#pragma once
-
-#include "esphome/core/automation.h"
-#include "esphome/core/component.h"
-#include "aic3204.h"
-
-namespace esphome::aic3204 {
-
-template<typename... Ts> class SetAutoMuteAction final : public Action<Ts...> {
- public:
-  explicit SetAutoMuteAction(AIC3204 *aic3204) : aic3204_(aic3204) {}
-
-  TEMPLATABLE_VALUE(uint8_t, auto_mute_mode)
-
-  void play(const Ts &...x) override { this->aic3204_->set_auto_mute_mode(this->auto_mute_mode_.value(x...)); }
-
- protected:
-  AIC3204 *aic3204_;
-};
-
-}  // namespace esphome::aic3204

esphome/components/alarm_control_panel/__init__.py

@@ -41,18 +41,6 @@ StateAnyForwarder = alarm_control_panel_ns.class_("StateAnyForwarder")
 StateEnterForwarder = alarm_control_panel_ns.class_("StateEnterForwarder")
 AlarmControlPanelState = alarm_control_panel_ns.enum("AlarmControlPanelState")
 
-ArmAwayAction = alarm_control_panel_ns.class_("ArmAwayAction", automation.Action)
-ArmHomeAction = alarm_control_panel_ns.class_("ArmHomeAction", automation.Action)
-ArmNightAction = alarm_control_panel_ns.class_("ArmNightAction", automation.Action)
-DisarmAction = alarm_control_panel_ns.class_("DisarmAction", automation.Action)
-PendingAction = alarm_control_panel_ns.class_("PendingAction", automation.Action)
-TriggeredAction = alarm_control_panel_ns.class_("TriggeredAction", automation.Action)
-ChimeAction = alarm_control_panel_ns.class_("ChimeAction", automation.Action)
-ReadyAction = alarm_control_panel_ns.class_("ReadyAction", automation.Action)
-
-AlarmControlPanelCondition = alarm_control_panel_ns.class_(
-    "AlarmControlPanelCondition", automation.Condition
-)
 
 _ALARM_CONTROL_PANEL_SCHEMA = (
     cv.ENTITY_BASE_SCHEMA.extend(web_server.WEBSERVER_SORTING_SCHEMA)
@@ -196,125 +184,38 @@ async def new_alarm_control_panel(config, *args):
     return var
 
 
-@automation.register_action(
-    "alarm_control_panel.arm_away",
-    ArmAwayAction,
-    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
-    synchronous=True,
-)
-async def alarm_action_arm_away_to_code(config, action_id, template_arg, args):
-    paren = await cg.get_variable(config[CONF_ID])
-    var = cg.new_Pvariable(action_id, template_arg, paren)
-    if code_config := config.get(CONF_CODE):
-        templatable_ = await cg.templatable(code_config, args, cg.std_string)
-        cg.add(var.set_code(templatable_))
-    return var
-
-
-@automation.register_action(
-    "alarm_control_panel.arm_home",
-    ArmHomeAction,
-    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
-    synchronous=True,
-)
-async def alarm_action_arm_home_to_code(config, action_id, template_arg, args):
-    paren = await cg.get_variable(config[CONF_ID])
-    var = cg.new_Pvariable(action_id, template_arg, paren)
-    if code_config := config.get(CONF_CODE):
-        templatable_ = await cg.templatable(code_config, args, cg.std_string)
-        cg.add(var.set_code(templatable_))
-    return var
-
-
-@automation.register_action(
-    "alarm_control_panel.arm_night",
-    ArmNightAction,
-    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
-    synchronous=True,
-)
-async def alarm_action_arm_night_to_code(config, action_id, template_arg, args):
-    paren = await cg.get_variable(config[CONF_ID])
-    var = cg.new_Pvariable(action_id, template_arg, paren)
-    if CONF_CODE in config:
-        templatable_ = await cg.templatable(config[CONF_CODE], args, cg.std_string)
-        cg.add(var.set_code(templatable_))
-    return var
-
-
-@automation.register_action(
-    "alarm_control_panel.disarm",
-    DisarmAction,
-    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
-    synchronous=True,
-)
-async def alarm_action_disarm_to_code(config, action_id, template_arg, args):
-    paren = await cg.get_variable(config[CONF_ID])
-    var = cg.new_Pvariable(action_id, template_arg, paren)
-    if code_config := config.get(CONF_CODE):
-        templatable_ = await cg.templatable(code_config, args, cg.std_string)
-        cg.add(var.set_code(templatable_))
-    return var
-
-
-@automation.register_action(
-    "alarm_control_panel.pending",
-    PendingAction,
-    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
-    synchronous=True,
-)
-async def alarm_action_pending_to_code(config, action_id, template_arg, args):
-    paren = await cg.get_variable(config[CONF_ID])
-    return cg.new_Pvariable(action_id, template_arg, paren)
-
-
-@automation.register_action(
-    "alarm_control_panel.triggered",
-    TriggeredAction,
-    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
-    synchronous=True,
-)
-async def alarm_action_trigger_to_code(config, action_id, template_arg, args):
-    paren = await cg.get_variable(config[CONF_ID])
-    return cg.new_Pvariable(action_id, template_arg, paren)
-
-
-@automation.register_action(
-    "alarm_control_panel.chime",
-    ChimeAction,
-    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
-    synchronous=True,
-)
-async def alarm_action_chime_to_code(config, action_id, template_arg, args):
-    paren = await cg.get_variable(config[CONF_ID])
-    return cg.new_Pvariable(action_id, template_arg, paren)
-
-
-@automation.register_action(
-    "alarm_control_panel.ready",
-    ReadyAction,
-    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
-    synchronous=True,
-)
-@automation.register_condition(
-    "alarm_control_panel.ready",
-    AlarmControlPanelCondition,
-    ALARM_CONTROL_PANEL_CONDITION_SCHEMA,
-)
-async def alarm_action_ready_to_code(config, action_id, template_arg, args):
-    paren = await cg.get_variable(config[CONF_ID])
-    return cg.new_Pvariable(action_id, template_arg, paren)
-
-
-@automation.register_condition(
-    "alarm_control_panel.is_armed",
-    AlarmControlPanelCondition,
-    ALARM_CONTROL_PANEL_CONDITION_SCHEMA,
-)
-async def alarm_control_panel_is_armed_to_code(
-    config, condition_id, template_arg, args
+# Mirrors AlarmControlPanel::arm_with_code_: arm first, set the code only when given.
+for _name, _arm in (
+    ("alarm_control_panel.arm_away", "arm_away()"),
+    ("alarm_control_panel.arm_home", "arm_home()"),
+    ("alarm_control_panel.arm_night", "arm_night()"),
+    ("alarm_control_panel.disarm", "disarm()"),
 ):
-    paren = await cg.get_variable(config[CONF_ID])
-    return cg.new_Pvariable(condition_id, template_arg, paren)
+    automation.register_apply_action(
+        _name,
+        ALARM_CONTROL_PANEL_ACTION_SCHEMA,
+        automation.ApplyCall(_arm),
+        automation.ApplyField(CONF_CODE, "set_code", cg.std_string),
+        call="make_call",
+    )
+
+
+for _name, _call in (
+    ("alarm_control_panel.pending", "pending()"),
+    ("alarm_control_panel.triggered", "triggered()"),
+):
+    automation.register_apply_action(
+        _name,
+        ALARM_CONTROL_PANEL_ACTION_SCHEMA,
+        automation.ApplyCall(_call),
+        call="make_call",
+    )
+
+
+for _name in ("alarm_control_panel.ready", "alarm_control_panel.is_armed"):
+    automation.register_apply_condition(
+        _name, ALARM_CONTROL_PANEL_CONDITION_SCHEMA, "is_armed_pending_or_triggered()"
+    )
 
 
 @coroutine_with_priority(CoroPriority.CORE)

esphome/components/alarm_control_panel/alarm_control_panel.h

@@ -130,6 +130,12 @@ class AlarmControlPanel : public EntityBase {
 
   // is the state one of the armed states
   bool is_state_armed(AlarmControlPanelState state);
+  /// Armed, pending (entry delay) or triggered; not ARMING (exit delay). Backs the is_armed and ready
+  /// conditions.
+  bool is_armed_pending_or_triggered() {
+    auto state = this->get_state();
+    return this->is_state_armed(state) || state == ACP_STATE_PENDING || state == ACP_STATE_TRIGGERED;
+  }
 
  protected:
   friend AlarmControlPanelCall;
@@ -138,11 +144,11 @@ class AlarmControlPanel : public EntityBase {
   // in order to store last panel state in flash
   ESPPreferenceObject pref_;
   // current state
-  AlarmControlPanelState current_state_;
+  AlarmControlPanelState current_state_{ACP_STATE_DISARMED};
   // the desired (or previous) state
-  AlarmControlPanelState desired_state_;
+  AlarmControlPanelState desired_state_{ACP_STATE_DISARMED};
   // last time the state was updated
-  uint32_t last_update_;
+  uint32_t last_update_{0};
   // the call control function
   virtual void control(const AlarmControlPanelCall &call) = 0;
   // state callback - passes the new state to listeners

esphome/components/alarm_control_panel/automation.h

@@ -27,84 +27,4 @@ static_assert(std::is_trivially_copyable_v<StateAnyForwarder>);
 static_assert(sizeof(StateEnterForwarder<ACP_STATE_TRIGGERED>) <= sizeof(void *));
 static_assert(std::is_trivially_copyable_v<StateEnterForwarder<ACP_STATE_TRIGGERED>>);
 
-template<typename... Ts> class ArmAwayAction final : public Action<Ts...> {
- public:
-  explicit ArmAwayAction(AlarmControlPanel *alarm_control_panel) : alarm_control_panel_(alarm_control_panel) {}
-
-  TEMPLATABLE_VALUE(std::string, code)
-
-  void play(const Ts &...x) override { this->alarm_control_panel_->arm_away(this->code_.optional_value(x...)); }
-
- protected:
-  AlarmControlPanel *alarm_control_panel_;
-};
-
-template<typename... Ts> class ArmHomeAction final : public Action<Ts...> {
- public:
-  explicit ArmHomeAction(AlarmControlPanel *alarm_control_panel) : alarm_control_panel_(alarm_control_panel) {}
-
-  TEMPLATABLE_VALUE(std::string, code)
-
-  void play(const Ts &...x) override { this->alarm_control_panel_->arm_home(this->code_.optional_value(x...)); }
-
- protected:
-  AlarmControlPanel *alarm_control_panel_;
-};
-
-template<typename... Ts> class ArmNightAction final : public Action<Ts...> {
- public:
-  explicit ArmNightAction(AlarmControlPanel *alarm_control_panel) : alarm_control_panel_(alarm_control_panel) {}
-
-  TEMPLATABLE_VALUE(std::string, code)
-
-  void play(const Ts &...x) override { this->alarm_control_panel_->arm_night(this->code_.optional_value(x...)); }
-
- protected:
-  AlarmControlPanel *alarm_control_panel_;
-};
-
-template<typename... Ts> class DisarmAction final : public Action<Ts...> {
- public:
-  explicit DisarmAction(AlarmControlPanel *alarm_control_panel) : alarm_control_panel_(alarm_control_panel) {}
-
-  TEMPLATABLE_VALUE(std::string, code)
-
-  void play(const Ts &...x) override { this->alarm_control_panel_->disarm(this->code_.optional_value(x...)); }
-
- protected:
-  AlarmControlPanel *alarm_control_panel_;
-};
-
-template<typename... Ts> class PendingAction final : public Action<Ts...> {
- public:
-  explicit PendingAction(AlarmControlPanel *alarm_control_panel) : alarm_control_panel_(alarm_control_panel) {}
-
-  void play(const Ts &...x) override { this->alarm_control_panel_->make_call().pending().perform(); }
-
- protected:
-  AlarmControlPanel *alarm_control_panel_;
-};
-
-template<typename... Ts> class TriggeredAction final : public Action<Ts...> {
- public:
-  explicit TriggeredAction(AlarmControlPanel *alarm_control_panel) : alarm_control_panel_(alarm_control_panel) {}
-
-  void play(const Ts &...x) override { this->alarm_control_panel_->make_call().triggered().perform(); }
-
- protected:
-  AlarmControlPanel *alarm_control_panel_;
-};
-
-template<typename... Ts> class AlarmControlPanelCondition final : public Condition<Ts...> {
- public:
-  AlarmControlPanelCondition(AlarmControlPanel *parent) : parent_(parent) {}
-  bool check(const Ts &...x) override {
-    return this->parent_->is_state_armed(this->parent_->get_state()) ||
-           this->parent_->get_state() == ACP_STATE_PENDING || this->parent_->get_state() == ACP_STATE_TRIGGERED;
-  }
-
- protected:
-  AlarmControlPanel *parent_;
-};
-
 }  // namespace esphome::alarm_control_panel

esphome/components/alpha3/alpha3.cpp

@@ -162,8 +162,9 @@ void Alpha3::send_request_(uint8_t *request, size_t len) {
   auto status =
       esp_ble_gattc_write_char(this->parent_->get_gattc_if(), this->parent_->get_conn_id(), this->geni_handle_, len,
                                request, ESP_GATT_WRITE_TYPE_NO_RSP, ESP_GATT_AUTH_REQ_NONE);
-  if (status)
+  if (status) {
     ESP_LOGW(TAG, "[%s] esp_ble_gattc_write_char failed, status=%d", this->parent_->address_str(), status);
+  }
 }
 
 void Alpha3::update() {

esphome/components/animation/animation.h

@@ -1,8 +1,6 @@
 #pragma once
 #include "esphome/components/image/image.h"
 
-#include "esphome/core/automation.h"
-
 namespace esphome::animation {
 
 class Animation final : public image::Image {
@@ -35,32 +33,4 @@ class Animation final : public image::Image {
   int loop_current_iteration_;
 };
 
-template<typename... Ts> class AnimationNextFrameAction final : public Action<Ts...> {
- public:
-  AnimationNextFrameAction(Animation *parent) : parent_(parent) {}
-  void play(const Ts &...x) override { this->parent_->next_frame(); }
-
- protected:
-  Animation *parent_;
-};
-
-template<typename... Ts> class AnimationPrevFrameAction final : public Action<Ts...> {
- public:
-  AnimationPrevFrameAction(Animation *parent) : parent_(parent) {}
-  void play(const Ts &...x) override { this->parent_->prev_frame(); }
-
- protected:
-  Animation *parent_;
-};
-
-template<typename... Ts> class AnimationSetFrameAction final : public Action<Ts...> {
- public:
-  AnimationSetFrameAction(Animation *parent) : parent_(parent) {}
-  TEMPLATABLE_VALUE(uint16_t, frame)
-  void play(const Ts &...x) override { this->parent_->set_frame(this->frame_.value(x...)); }
-
- protected:
-  Animation *parent_;
-};
-
 }  // namespace esphome::animation

esphome/components/animation/image.py

@@ -6,8 +6,6 @@ from esphome.components.file.image import image_schema, write_image
 from esphome.components.image import Image_, validate_settings
 import esphome.config_validation as cv
 from esphome.const import CONF_ID, CONF_REPEAT
-from esphome.core import ID
-from esphome.cpp_generator import MockObj, TemplateArgsType
 from esphome.types import ConfigType
 
 CODEOWNERS = ["@syndlex"]
@@ -26,17 +24,6 @@ animation_ns = cg.esphome_ns.namespace("animation")
 
 Animation_ = animation_ns.class_("Animation", Image_)
 
-# Actions
-NextFrameAction = animation_ns.class_(
-    "AnimationNextFrameAction", automation.Action, cg.Parented.template(Animation_)
-)
-PrevFrameAction = animation_ns.class_(
-    "AnimationPrevFrameAction", automation.Action, cg.Parented.template(Animation_)
-)
-SetFrameAction = animation_ns.class_(
-    "AnimationSetFrameAction", automation.Action, cg.Parented.template(Animation_)
-)
-
 ANIMATION_SCHEMA = image_schema(Animation_).extend(
     {
         cv.Optional(CONF_LOOP): cv.All(
@@ -72,28 +59,17 @@ SET_FRAME_SCHEMA = cv.Schema(
 )
 
 
-@automation.register_action(
-    "animation.next_frame", NextFrameAction, NEXT_FRAME_SCHEMA, synchronous=True
+automation.register_apply_action(
+    "animation.next_frame", NEXT_FRAME_SCHEMA, automation.ApplyCall("next_frame()")
 )
-@automation.register_action(
-    "animation.prev_frame", PrevFrameAction, PREV_FRAME_SCHEMA, synchronous=True
+automation.register_apply_action(
+    "animation.prev_frame", PREV_FRAME_SCHEMA, automation.ApplyCall("prev_frame()")
 )
-@automation.register_action(
-    "animation.set_frame", SetFrameAction, SET_FRAME_SCHEMA, synchronous=True
+automation.register_apply_action(
+    "animation.set_frame",
+    SET_FRAME_SCHEMA,
+    automation.ApplyField(CONF_FRAME, "set_frame", cg.uint16),
 )
-async def animation_action_to_code(
-    config: ConfigType,
-    action_id: ID,
-    template_arg: cg.TemplateArguments,
-    args: TemplateArgsType,
-) -> MockObj:
-    paren = await cg.get_variable(config[CONF_ID])
-    var = cg.new_Pvariable(action_id, template_arg, paren)
-
-    if (frame := config.get(CONF_FRAME)) is not None:
-        template_ = await cg.templatable(frame, args, cg.uint16)
-        cg.add(var.set_frame(template_))
-    return var
 
 
 async def setup_animation(config: ConfigType) -> None:

esphome/components/anova/anova.cpp

@@ -13,7 +13,7 @@ void Anova::dump_config() { LOG_CLIMATE("", "Anova BLE Cooker", this); }
 
 void Anova::setup() {
   this->codec_ = make_unique<AnovaCodec>();
-  this->current_request_ = 0;
+  this->poll_step_ = PollStep::IDLE;
 }
 
 void Anova::loop() {
@@ -22,6 +22,15 @@ void Anova::loop() {
   this->disable_loop();
 }
 
+void Anova::write_request_(AnovaPacket *pkt) {
+  auto status =
+      esp_ble_gattc_write_char(this->parent_->get_gattc_if(), this->parent_->get_conn_id(), this->char_handle_,
+                               pkt->length, pkt->data, ESP_GATT_WRITE_TYPE_NO_RSP, ESP_GATT_AUTH_REQ_NONE);
+  if (status) {
+    ESP_LOGW(TAG, "[%s] esp_ble_gattc_write_char failed, status=%d", this->parent_->address_str(), status);
+  }
+}
+
 void Anova::control(const ClimateCall &call) {
   auto mode_val = call.get_mode();
   if (mode_val.has_value()) {
@@ -38,22 +47,11 @@ void Anova::control(const ClimateCall &call) {
         ESP_LOGW(TAG, "Unsupported mode: %d", mode);
         return;
     }
-    auto status =
-        esp_ble_gattc_write_char(this->parent_->get_gattc_if(), this->parent_->get_conn_id(), this->char_handle_,
-                                 pkt->length, pkt->data, ESP_GATT_WRITE_TYPE_NO_RSP, ESP_GATT_AUTH_REQ_NONE);
-    if (status) {
-      ESP_LOGW(TAG, "[%s] esp_ble_gattc_write_char failed, status=%d", this->parent_->address_str(), status);
-    }
+    this->write_request_(pkt);
   }
   auto target_temp = call.get_target_temperature();
   if (target_temp.has_value()) {
-    auto *pkt = this->codec_->get_set_target_temp_request(*target_temp);
-    auto status =
-        esp_ble_gattc_write_char(this->parent_->get_gattc_if(), this->parent_->get_conn_id(), this->char_handle_,
-                                 pkt->length, pkt->data, ESP_GATT_WRITE_TYPE_NO_RSP, ESP_GATT_AUTH_REQ_NONE);
-    if (status) {
-      ESP_LOGW(TAG, "[%s] esp_ble_gattc_write_char failed, status=%d", this->parent_->address_str(), status);
-    }
+    this->write_request_(this->codec_->get_set_target_temp_request(*target_temp));
   }
 }
 
@@ -62,6 +60,7 @@ void Anova::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_t gattc_
     case ESP_GATTC_DISCONNECT_EVT: {
       this->current_temperature = NAN;
       this->target_temperature = NAN;
+      this->poll_step_ = PollStep::IDLE;
       this->publish_state();
       break;
     }
@@ -83,8 +82,8 @@ void Anova::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_t gattc_
     }
     case ESP_GATTC_REG_FOR_NOTIFY_EVT: {
       this->node_state = espbt::ClientState::ESTABLISHED;
-      this->current_request_ = 0;
-      this->update();
+      this->poll_step_ = PollStep::IDLE;
+      this->update();  // begin the first poll cycle immediately
       break;
     }
     case ESP_GATTC_NOTIFY_EVT: {
@@ -101,33 +100,30 @@ void Anova::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_t gattc_
         this->mode = this->codec_->running_ ? climate::CLIMATE_MODE_HEAT : climate::CLIMATE_MODE_OFF;
       }
       if (this->codec_->has_unit()) {
-        this->fahrenheit_ = (this->codec_->unit_ == 'f');
-        ESP_LOGD(TAG, "Anova units is %s", this->fahrenheit_ ? "fahrenheit" : "celsius");
-        this->current_request_++;
+        ESP_LOGD(TAG, "Anova units is %s", (this->codec_->unit_ == 'f') ? "fahrenheit" : "celsius");
       }
       this->publish_state();
 
-      if (this->current_request_ > 1) {
-        AnovaPacket *pkt = nullptr;
-        switch (this->current_request_++) {
-          case 2:
-            pkt = this->codec_->get_read_target_temp_request();
-            break;
-          case 3:
-            pkt = this->codec_->get_read_current_temp_request();
-            break;
-          default:
-            this->current_request_ = 1;
-            break;
-        }
-        if (pkt != nullptr) {
-          auto status =
-              esp_ble_gattc_write_char(this->parent_->get_gattc_if(), this->parent_->get_conn_id(), this->char_handle_,
-                                       pkt->length, pkt->data, ESP_GATT_WRITE_TYPE_NO_RSP, ESP_GATT_AUTH_REQ_NONE);
-          if (status) {
-            ESP_LOGW(TAG, "[%s] esp_ble_gattc_write_char failed, status=%d", this->parent_->address_str(), status);
-          }
-        }
+      // Advance the poll cycle to its next request based on the reply we got.
+      switch (this->poll_step_) {
+        case PollStep::SET_UNIT:
+          this->poll_step_ = PollStep::STATUS;
+          this->write_request_(this->codec_->get_read_device_status_request());
+          break;
+        case PollStep::STATUS:
+          this->poll_step_ = PollStep::TARGET;
+          this->write_request_(this->codec_->get_read_target_temp_request());
+          break;
+        case PollStep::TARGET:
+          this->poll_step_ = PollStep::CURRENT;
+          this->write_request_(this->codec_->get_read_current_temp_request());
+          break;
+        case PollStep::CURRENT:
+          this->poll_step_ = PollStep::IDLE;  // full cycle complete
+          break;
+        default:
+          // A reply to an ad-hoc control() write, outside a managed cycle.
+          break;
       }
       break;
     }
@@ -136,27 +132,26 @@ void Anova::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_t gattc_
   }
 }
 
-void Anova::set_unit_of_measurement(const char *unit) { this->fahrenheit_ = !strncmp(unit, "f", 1); }
+void Anova::set_unit_of_measurement(const char *unit) { this->want_fahrenheit_ = !strncmp(unit, "f", 1); }
 
 void Anova::update() {
   if (this->node_state != espbt::ClientState::ESTABLISHED)
     return;
-
-  if (this->current_request_ < 2) {
-    AnovaPacket *pkt;
-    if (this->current_request_ == 0) {
-      pkt = this->codec_->get_set_unit_request(this->fahrenheit_ ? 'f' : 'c');
-    } else {
-      pkt = this->codec_->get_read_device_status_request();
-    }
-    auto status =
-        esp_ble_gattc_write_char(this->parent_->get_gattc_if(), this->parent_->get_conn_id(), this->char_handle_,
-                                 pkt->length, pkt->data, ESP_GATT_WRITE_TYPE_NO_RSP, ESP_GATT_AUTH_REQ_NONE);
-    if (status) {
-      ESP_LOGW(TAG, "[%s] esp_ble_gattc_write_char failed, status=%d", this->parent_->address_str(), status);
-    }
-    this->current_request_++;
+  if (this->poll_step_ != PollStep::IDLE) {
+    // The previous cycle never finished within a full polling interval -- a
+    // reply was missed or a write failed. Restart the cycle rather than stall;
+    // the polling interval itself acts as the timeout. A late reply from the
+    // abandoned cycle is harmless: state decoding happens on every notify
+    // regardless of step, and each notify sends at most one follow-up request.
+    ESP_LOGW(TAG, "[%s] Poll cycle incomplete (step %u); restarting cycle", this->parent_->address_str(),
+             static_cast<uint8_t>(this->poll_step_));
   }
+  // Re-assert the configured unit at the start of every poll cycle, then fall
+  // through the status/temperature reads via the notification handler. Always
+  // command the configured unit (want_fahrenheit_) -- never the last value the
+  // device reported, or a drift to 'c' would lock itself in.
+  this->poll_step_ = PollStep::SET_UNIT;
+  this->write_request_(this->codec_->get_set_unit_request(this->want_fahrenheit_ ? 'f' : 'c'));
 }
 
 }  // namespace esphome::anova

esphome/components/anova/anova.h

@@ -37,11 +37,20 @@ class Anova final : public climate::Climate, public esphome::ble_client::BLEClie
   void set_unit_of_measurement(const char *unit);
 
  protected:
+  // A poll cycle re-asserts the configured unit, then reads device state.
+  // Re-asserting every cycle prevents the cooker from silently reverting to
+  // its default (Celsius); previously the unit was only set once on
+  // connection, so a drift persisted (and corrupted the F/C interpretation of
+  // subsequent readings) until the BLE link was re-established.
+  enum class PollStep : uint8_t { SET_UNIT, STATUS, TARGET, CURRENT, IDLE };
+
+  void write_request_(AnovaPacket *pkt);
+
   std::unique_ptr<AnovaCodec> codec_;
   void control(const climate::ClimateCall &call) override;
   uint16_t char_handle_;
-  uint8_t current_request_;
-  bool fahrenheit_;
+  bool want_fahrenheit_{true};  // configured target unit; never overwritten by device replies
+  PollStep poll_step_{PollStep::IDLE};
 };
 
 }  // namespace esphome::anova

esphome/components/api/__init__.py

@@ -1,9 +1,11 @@
 import logging
+import re
 from typing import Any
 
 from esphome import automation
 from esphome.automation import Condition
 import esphome.codegen as cg
+from esphome.components.const import CONF_DESCRIPTION
 from esphome.components.logger import request_log_listener
 
 # ENCRYPTION_SCHEMA and validate_encryption_key are re-exported for external
@@ -12,6 +14,7 @@ from esphome.components.noise import (  # noqa: F401
     ENCRYPTION_SCHEMA,
     decode_encryption_key,
     encryption_schema,
+    new_psk_progmem,
     validate_encryption_key,
 )
 from esphome.config_helpers import filter_source_files_from_defines, get_logger_level
@@ -40,10 +43,12 @@ from esphome.const import (
     CONF_TAG,
     CONF_THEN,
     CONF_TRIGGER_ID,
+    CONF_TYPE,
     CONF_VARIABLES,
 )
 from esphome.core import CORE, ID, CoroPriority, EsphomeError, coroutine_with_priority
 from esphome.cpp_generator import MockObj, TemplateArgsType
+from esphome.helpers import fnv1_hash
 from esphome.types import ConfigFragmentType, ConfigType
 
 # Compat alias: downstream consumers (e.g. device-builder) referenced the
@@ -76,7 +81,7 @@ def AUTO_LOAD(config: ConfigType) -> list[str]:
 
 
 api_ns = cg.esphome_ns.namespace("api")
-APIServer = api_ns.class_("APIServer", cg.Component, cg.Controller)
+APIServer = api_ns.class_("APIServer", cg.Component)
 HomeAssistantServiceCallAction = api_ns.class_(
     "HomeAssistantServiceCallAction", automation.Action
 )
@@ -124,12 +129,19 @@ SERVICE_ARG_FALLBACK_TYPES: dict[str, MockObj] = {
 }
 CONF_BATCH_DELAY = "batch_delay"
 CONF_CUSTOM_SERVICES = "custom_services"
+CONF_EXAMPLE = "example"
 CONF_HOMEASSISTANT_SERVICES = "homeassistant_services"
 CONF_HOMEASSISTANT_STATES = "homeassistant_states"
 CONF_LISTEN_BACKLOG = "listen_backlog"
 CONF_MAX_SEND_QUEUE = "max_send_queue"
 CONF_STATE_SUBSCRIPTION_ONLY = "state_subscription_only"
 
+# Schema defaults that also match the C++ initializers in api_server.h; codegen
+# skips the setter when the config equals them.
+DEFAULT_PORT = 6053
+DEFAULT_REBOOT_TIMEOUT = "15min"
+DEFAULT_BATCH_DELAY = "100ms"
+
 
 def _register_provisioning_source(config: ConfigType) -> ConfigType:
     """Register the API as a provisioning source when encryption is enabled.
@@ -227,14 +239,30 @@ def _validate_supports_response(value: Any) -> str:
     return cv.enum(SUPPORTS_RESPONSE_OPTIONS, lower=True)(value)
 
 
+# ESP8266 copies every string of an action into a stack buffer sized by codegen; keep it small
+ESP8266_ACTION_STRINGS_MAX_TOTAL = 384
+
+VARIABLE_SCHEMA = cv.Schema(
+    {
+        cv.Required(CONF_TYPE): cv.one_of(*SERVICE_ARG_NATIVE_TYPES, lower=True),
+        cv.Optional(CONF_DESCRIPTION): cv.string_strict,
+        cv.Optional(CONF_EXAMPLE): cv.string_strict,
+    }
+)
+
+# Accepts the plain `name: type` shorthand or the full mapping form
+validate_variable = cv.maybe_simple_value(VARIABLE_SCHEMA, key=CONF_TYPE)
+
+
 ACTIONS_SCHEMA = automation.validate_automation(
     {
         cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(UserServiceTrigger),
         cv.Exclusive(CONF_SERVICE, group_of_exclusion=CONF_ACTION): cv.valid_name,
         cv.Exclusive(CONF_ACTION, group_of_exclusion=CONF_ACTION): cv.valid_name,
+        cv.Optional(CONF_DESCRIPTION): cv.string_strict,
         cv.Optional(CONF_VARIABLES, default={}): cv.Schema(
             {
-                cv.validate_id_name: cv.one_of(*SERVICE_ARG_NATIVE_TYPES, lower=True),
+                cv.validate_id_name: validate_variable,
             }
         ),
         # No default - auto-detected by _auto_detect_supports_response
@@ -270,7 +298,7 @@ CONFIG_SCHEMA = cv.All(
     cv.Schema(
         {
             cv.GenerateID(): cv.declare_id(APIServer),
-            cv.Optional(CONF_PORT, default=6053): cv.port,
+            cv.Optional(CONF_PORT, default=DEFAULT_PORT): cv.port,
             # Removed in 2026.1.0 - kept to provide helpful error message
             cv.Optional(CONF_PASSWORD): cv.invalid(
                 "The 'password' option has been removed in ESPHome 2026.1.0.\n"
@@ -283,14 +311,14 @@ CONFIG_SCHEMA = cv.All(
                 "Or visit https://esphome.io/components/api/#configuration-variables"
             ),
             cv.Optional(
-                CONF_REBOOT_TIMEOUT, default="15min"
+                CONF_REBOOT_TIMEOUT, default=DEFAULT_REBOOT_TIMEOUT
             ): cv.positive_time_period_milliseconds,
             cv.Exclusive(
                 CONF_SERVICES, group_of_exclusion=CONF_ACTIONS
             ): ACTIONS_SCHEMA,
             cv.Exclusive(CONF_ACTIONS, group_of_exclusion=CONF_ACTIONS): ACTIONS_SCHEMA,
             cv.Optional(CONF_ENCRYPTION): encryption_schema,
-            cv.Optional(CONF_BATCH_DELAY, default="100ms"): cv.All(
+            cv.Optional(CONF_BATCH_DELAY, default=DEFAULT_BATCH_DELAY): cv.All(
                 cv.positive_time_period_milliseconds,
                 cv.Range(max=cv.TimePeriod(milliseconds=65535)),
             ),
@@ -328,10 +356,9 @@ CONFIG_SCHEMA = cv.All(
                 ln882x=5,  # Moderate RAM
                 nrf52=4,  # ~256KB RAM, BSD sockets, Thread (single HA controller)
             ): cv.int_range(min=1, max=20),
-            # Maximum queued send buffers per connection before dropping connection
-            # Each buffer uses ~8-12 bytes overhead plus actual message size
+            # Max queued messages per connection, and 2 KB of backlog per slot up
+            # to 64 KB (a lone message is exempt), before the connection is dropped
             # Platform defaults based on available RAM and typical message rates:
-            # CONF_MAX_SEND_QUEUE defaults are power of 2 for efficient modulo
             cv.SplitDefault(
                 CONF_MAX_SEND_QUEUE,
                 esp8266=4,  # Limited RAM, need to fail fast
@@ -351,27 +378,113 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
+def _has_action_metadata(actions: list[ConfigType]) -> bool:
+    # Empty strings count as unset, matching _action_strings
+    return any(
+        conf.get(CONF_DESCRIPTION)
+        or any(
+            var_.get(CONF_DESCRIPTION) or var_.get(CONF_EXAMPLE)
+            for var_ in conf[CONF_VARIABLES].values()
+        )
+        for conf in actions
+    )
+
+
+def _action_strings(conf: ConfigType, has_metadata: bool) -> list[str | None]:
+    """Strings of one action in the table order UserServiceStatic (user_services.h) expects."""
+    # An empty description or example is treated as unset
+    strings: list[str | None] = [conf[CONF_ACTION]]
+    if has_metadata:
+        strings.append(conf.get(CONF_DESCRIPTION) or None)
+    for name, var_ in conf[CONF_VARIABLES].items():
+        strings.append(name)
+        if has_metadata:
+            strings += [
+                var_.get(CONF_DESCRIPTION) or None,
+                var_.get(CONF_EXAMPLE) or None,
+            ]
+    return strings
+
+
+def _action_strings_size(strings: list[str | None]) -> int:
+    """Bytes needed to copy every string out of flash, each with its terminator."""
+    return sum(
+        len(string.encode("utf-8")) + 1 for string in strings if string is not None
+    )
+
+
+def _validate_esp8266_action_strings(config: ConfigType) -> ConfigType:
+    if not CORE.is_esp8266:
+        return config
+    actions = config.get(CONF_ACTIONS, [])
+    has_metadata = _has_action_metadata(actions)
+    for conf in actions:
+        size = _action_strings_size(_action_strings(conf, has_metadata))
+        if size > ESP8266_ACTION_STRINGS_MAX_TOTAL:
+            raise cv.Invalid(
+                f"Action '{conf[CONF_ACTION]}' has {size} bytes of name, variable name, "
+                f"description and example text; ESP8266 allows at most "
+                f"{ESP8266_ACTION_STRINGS_MAX_TOTAL} bytes per action"
+            )
+    return config
+
+
+FINAL_VALIDATE_SCHEMA = _validate_esp8266_action_strings
+
+
+def _add_action_strings(
+    index: int, strings: list[str | None], interned: dict[str, MockObj]
+) -> MockObj:
+    """Emit the PROGMEM string table for one action.
+
+    Each string is its own PROGMEM array because on ESP8266 .rodata is RAM, and identical
+    strings are shared between actions through `interned`.
+    """
+    entries: list[MockObj] = []
+    for string in strings:
+        if string is None:
+            entries.append(cg.nullptr)
+            continue
+        if (var := interned.get(string)) is None:
+            var = interned[string] = cg.progmem_array(
+                ID(f"api_action_str{len(interned)}", is_declaration=True, type=cg.char),
+                string,
+            )
+        entries.append(var)
+    return cg.progmem_array(
+        ID(f"api_action{index}_strings", is_declaration=True, type=cg.const_char_ptr),
+        entries,
+    )
+
+
 @coroutine_with_priority(CoroPriority.WEB)
 async def to_code(config: ConfigType) -> None:
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
 
-    # Track controller registration for StaticVector sizing
-    CORE.register_controller()
+    CORE.register_controller(var)
 
     # Request a log listener slot for API log streaming
     request_log_listener()
 
-    cg.add(var.set_port(config[CONF_PORT]))
-    cg.add(var.set_reboot_timeout(config[CONF_REBOOT_TIMEOUT]))
-    cg.add(var.set_batch_delay(config[CONF_BATCH_DELAY]))
+    # Skip the setters when the config matches the C++ initializers (DEFAULT_*).
+    if (port := config[CONF_PORT]) != DEFAULT_PORT:
+        cg.add(var.set_port(port))
+    if (reboot_timeout := config[CONF_REBOOT_TIMEOUT]) != cv.time_period(
+        DEFAULT_REBOOT_TIMEOUT
+    ):
+        cg.add(var.set_reboot_timeout(reboot_timeout))
+    if (batch_delay := config[CONF_BATCH_DELAY]) != cv.time_period(DEFAULT_BATCH_DELAY):
+        cg.add(var.set_batch_delay(batch_delay))
     if CONF_LISTEN_BACKLOG in config:
         cg.add(var.set_listen_backlog(config[CONF_LISTEN_BACKLOG]))
     cg.add_define("MAX_API_CONNECTIONS", config[CONF_MAX_CONNECTIONS])
     cg.add_define("API_MAX_SEND_QUEUE", config[CONF_MAX_SEND_QUEUE])
 
+    actions = config.get(CONF_ACTIONS, [])
+    has_user_actions = bool(actions) or config[CONF_CUSTOM_SERVICES]
     # Set USE_API_USER_DEFINED_ACTIONS if any services are enabled
-    if config.get(CONF_ACTIONS) or config[CONF_CUSTOM_SERVICES]:
+    if has_user_actions:
         cg.add_define("USE_API_USER_DEFINED_ACTIONS")
 
     # Set USE_API_CUSTOM_SERVICES if external components need dynamic service registration
@@ -384,10 +497,17 @@ async def to_code(config: ConfigType) -> None:
     if config[CONF_HOMEASSISTANT_STATES]:
         cg.add_define("USE_API_HOMEASSISTANT_STATES")
 
-    if actions := config.get(CONF_ACTIONS, []):
+    scratch_size = 0
+    if actions:
+        # Metadata is compiled in for every action once any action declares it, because the
+        # string table layout is fixed by the define rather than per action
+        has_metadata = _has_action_metadata(actions)
+        if has_metadata:
+            cg.add_define("USE_API_USER_DEFINED_ACTION_METADATA")
+        interned_strings: dict[str, MockObj] = {}
         # Collect all triggers first, then register all at once with initializer_list
         triggers: list[cg.MockObj] = []
-        for conf in actions:
+        for index, conf in enumerate(actions):
             func_args: list[tuple[MockObj, str]] = []
             service_template_args: list[MockObj] = []  # User service argument types
 
@@ -420,22 +540,23 @@ async def to_code(config: ConfigType) -> None:
                 conf.get(CONF_THEN, [])
             )
 
-            service_arg_names: list[str] = []
             for name, var_ in conf[CONF_VARIABLES].items():
-                if has_non_synchronous and var_ in SERVICE_ARG_FALLBACK_TYPES:
-                    native = SERVICE_ARG_FALLBACK_TYPES[var_]
+                var_type = var_[CONF_TYPE]
+                if has_non_synchronous and var_type in SERVICE_ARG_FALLBACK_TYPES:
+                    native = SERVICE_ARG_FALLBACK_TYPES[var_type]
                 else:
-                    native = SERVICE_ARG_NATIVE_TYPES[var_]
+                    native = SERVICE_ARG_NATIVE_TYPES[var_type]
                 service_template_args.append(native)
                 func_args.append((native, name))
-                service_arg_names.append(name)
+            strings = _action_strings(conf, has_metadata)
+            table = _add_action_strings(index, strings, interned_strings)
+            if CORE.is_esp8266:
+                scratch_size = max(scratch_size, _action_strings_size(strings))
             # Template args: supports_response mode, then user service arg types
             templ = cg.TemplateArguments(supports_response, *service_template_args)
+            # Key is hashed here because the name is not readable at runtime on ESP8266
             trigger = cg.new_Pvariable(
-                conf[CONF_TRIGGER_ID],
-                templ,
-                conf[CONF_ACTION],
-                service_arg_names,
+                conf[CONF_TRIGGER_ID], templ, table, fnv1_hash(conf[CONF_ACTION])
             )
             triggers.append(trigger)
             auto = await automation.build_automation(trigger, func_args, conf)
@@ -457,6 +578,9 @@ async def to_code(config: ConfigType) -> None:
                 cg.add(auto.add_actions([unregister_action]))
         # Register all services at once - single allocation, no reallocations
         cg.add(var.initialize_user_services(triggers))
+    if CORE.is_esp8266 and has_user_actions:
+        # Stack buffer that list-entities copies PROGMEM strings into, sized for the largest action
+        cg.add_define("API_USER_ACTION_STRINGS_SCRATCH_SIZE", max(scratch_size, 1))
 
     if CONF_ON_CLIENT_CONNECTED in config:
         cg.add_define("USE_API_CLIENT_CONNECTED_TRIGGER")
@@ -476,8 +600,7 @@ async def to_code(config: ConfigType) -> None:
 
     if (encryption_config := config.get(CONF_ENCRYPTION, None)) is not None:
         if key := encryption_config.get(CONF_KEY):
-            decoded = decode_encryption_key(key)
-            cg.add(var.set_noise_psk(list(decoded)))
+            cg.add(var.set_noise_psk(new_psk_progmem(config[CONF_ID], key)))
             cg.add_define("USE_API_NOISE_PSK_FROM_YAML")
         else:
             # No key provided, but encryption desired
@@ -499,6 +622,40 @@ async def to_code(config: ConfigType) -> None:
 
 KEY_VALUE_SCHEMA = cv.Schema({cv.string: cv.templatable(cv.string_strict)})
 
+_ID_CALL_PROG = re.compile(r"\bid\s*\(")
+
+
+# Remove before 2027.3.0: untagged strings that look like lambda source keep
+# being compiled as lambdas during the deprecation window
+def _coerce_implicit_lambda(value: Any) -> Any:
+    if not isinstance(value, str):
+        return value
+    if cv.looks_like_returning_lambda(value):
+        _LOGGER.warning(
+            "[api] The 'variables' value '%s' looks like a lambda but is "
+            "missing the !lambda tag. It is compiled as a lambda for now but "
+            "will be sent as literal text from 2027.3.0. Add !lambda to keep "
+            "it evaluated; literal text belongs under 'data:'.",
+            value,
+        )
+        # cv.templatable runs returning_lambda on the coerced Lambda
+        return cv.lambda_(value)
+    if _ID_CALL_PROG.search(value):
+        # lambda source without a return: issue 5394's mistake class
+        _LOGGER.warning(
+            "[api] The 'variables' value '%s' is sent as literal text; wrap "
+            "it in !lambda 'return ...;' to evaluate it instead.",
+            value,
+        )
+    return value
+
+
+# Static strings or !lambda values. cv.templatable stays introspectable for
+# schema tooling; removing the shim leaves KEY_VALUE_SCHEMA.
+VARIABLES_SCHEMA = cv.Schema(
+    {cv.string: cv.All(_coerce_implicit_lambda, cv.templatable(cv.string_strict))}
+)
+
 
 def _validate_response_config(config: ConfigType) -> ConfigType:
     # Validate dependencies:
@@ -535,9 +692,7 @@ HOMEASSISTANT_ACTION_ACTION_SCHEMA = cv.All(
             ),
             cv.Optional(CONF_DATA, default={}): KEY_VALUE_SCHEMA,
             cv.Optional(CONF_DATA_TEMPLATE, default={}): KEY_VALUE_SCHEMA,
-            cv.Optional(CONF_VARIABLES, default={}): cv.Schema(
-                {cv.string: cv.returning_lambda}
-            ),
+            cv.Optional(CONF_VARIABLES, default={}): VARIABLES_SCHEMA,
             cv.Optional(CONF_RESPONSE_TEMPLATE): cv.templatable(cv.string),
             cv.Optional(CONF_CAPTURE_RESPONSE, default=False): cv.boolean,
             cv.Optional(CONF_ON_SUCCESS): automation.validate_automation(single=True),
@@ -598,6 +753,8 @@ async def homeassistant_service_to_code(
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
         templ = await cg.templatable(value, args, None)
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
         cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
     if on_error := config.get(CONF_ON_ERROR):
@@ -652,7 +809,7 @@ HOMEASSISTANT_EVENT_ACTION_SCHEMA = cv.Schema(
         cv.Required(CONF_EVENT): validate_homeassistant_event,
         cv.Optional(CONF_DATA, default={}): KEY_VALUE_SCHEMA,
         cv.Optional(CONF_DATA_TEMPLATE, default={}): KEY_VALUE_SCHEMA,
-        cv.Optional(CONF_VARIABLES, default={}): KEY_VALUE_SCHEMA,
+        cv.Optional(CONF_VARIABLES, default={}): VARIABLES_SCHEMA,
     }
 )
 
@@ -698,6 +855,8 @@ async def homeassistant_event_to_code(
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
         templ = await cg.templatable(value, args, None)
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
         cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
     return var

esphome/components/api/api.proto

@@ -77,6 +77,7 @@ service APIConnection {
   rpc serial_proxy_set_modem_pins(SerialProxySetModemPinsRequest) returns (void) {}
   rpc serial_proxy_get_modem_pins(SerialProxyGetModemPinsRequest) returns (void) {}
   rpc serial_proxy_request(SerialProxyRequest) returns (void) {}
+  rpc serial_proxy_set_mode(SerialProxySetModeRequest) returns (void) {}
 }
 
 
@@ -232,6 +233,7 @@ enum SerialProxyPortType {
 message SerialProxyInfo {
   string name = 1;                    // Human-readable port name
   SerialProxyPortType port_type = 2;  // Port type (RS232, RS485)
+  uint32 configured_line_states = 3;  // Bitmask of SerialProxyLineStateFlags this instance can drive
 }
 
 // DeviceInfoResponse max_data_length values:
@@ -801,6 +803,9 @@ message SwitchStateResponse {
   fixed32 key = 1 [(force) = true];
   bool state = 2;
   uint32 device_id = 3 [(field_ifdef) = "USE_DEVICES"];
+  // If the switch does not have a valid state yet.
+  // Equivalent to `!obj->has_state()` - inverse logic to make state packets smaller
+  bool missing_state = 4;
 }
 message SwitchCommandRequest {
   option (id) = 33;
@@ -1033,6 +1038,8 @@ message ListEntitiesServicesArgument {
   option (ifdef) = "USE_API_USER_DEFINED_ACTIONS";
   string name = 1;
   ServiceArgType type = 2;
+  string description = 3 [(field_ifdef) = "USE_API_USER_DEFINED_ACTION_METADATA"];
+  string example = 4 [(field_ifdef) = "USE_API_USER_DEFINED_ACTION_METADATA"];
 }
 message ListEntitiesServicesResponse {
   option (id) = 41;
@@ -1043,6 +1050,7 @@ message ListEntitiesServicesResponse {
   fixed32 key = 2 [(force) = true];
   repeated ListEntitiesServicesArgument args = 3 [(fixed_vector) = true];
   SupportsResponseType supports_response = 4;
+  string description = 5 [(field_ifdef) = "USE_API_USER_DEFINED_ACTION_METADATA"];
 }
 message ExecuteServiceArgument {
   option (ifdef) = "USE_API_USER_DEFINED_ACTIONS";
@@ -1239,6 +1247,9 @@ message ClimateStateResponse {
   float current_humidity = 14;
   float target_humidity = 15;
   uint32 device_id = 16 [(field_ifdef) = "USE_DEVICES"];
+  // If the climate device does not have a valid state yet.
+  // Equivalent to `!obj->has_state()` - inverse logic to make state packets smaller
+  bool missing_state = 17;
 }
 message ClimateCommandRequest {
   option (id) = 48;
@@ -1325,6 +1336,9 @@ message WaterHeaterStateResponse {
   uint32 state = 6;
   float target_temperature_low = 7;
   float target_temperature_high = 8;
+  // If the water heater does not have a valid state yet.
+  // Equivalent to `!obj->has_state()` - inverse logic to make state packets smaller
+  bool missing_state = 9;
 }
 
 // Bitmask for WaterHeaterCommandRequest.has_fields
@@ -1653,7 +1667,8 @@ message ListEntitiesMediaPlayerResponse {
   bool disabled_by_default = 6;
   EntityCategory entity_category = 7;
 
-  bool supports_pause = 8;
+  // Deprecated in ESPHome 2026.9.0; use feature_flags instead.
+  bool supports_pause = 8 [deprecated = true];
 
   repeated MediaPlayerSupportedFormat supported_formats = 9;
 
@@ -2626,6 +2641,22 @@ message ZWaveProxyRequest {
   bytes data = 2;
 }
 
+enum ZWaveProxyStatus {
+  ZWAVE_PROXY_STATUS_OK = 0;             // Request completed successfully
+  ZWAVE_PROXY_STATUS_IN_USE = 1;         // Denied: another client is already subscribed
+  ZWAVE_PROXY_STATUS_NOT_SUPPORTED = 2;  // Request type not supported
+}
+
+// Acknowledges a ZWaveProxyRequest (subscribe/unsubscribe). Sent since API 1.16.
+message ZWaveProxyRequestResponse {
+  option (id) = 151;
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_ZWAVE_PROXY";
+
+  ZWaveProxyRequestType type = 1;  // Which request type this responds to
+  ZWaveProxyStatus status = 2;     // Result status
+}
+
 // ==================== INFRARED ====================
 // Note: Feature and capability flag enums are defined in
 // esphome/components/infrared/infrared.h
@@ -2705,7 +2736,8 @@ enum SerialProxyParity {
   SERIAL_PROXY_PARITY_ODD = 2;
 }
 
-// Configure UART parameters for a serial proxy instance
+// Configure UART parameters for a serial proxy instance. Only the subscribed client may
+// configure the port; others are refused with PORT_IN_USE (since API 1.17).
 message SerialProxyConfigureRequest {
   option (id) = 138;
   option (source) = SOURCE_CLIENT;
@@ -2731,7 +2763,8 @@ message SerialProxyDataReceived {
   bytes data = 2;               // Raw data received from the serial device
 }
 
-// Write data to a serial device
+// Write data to a serial device. Only the subscribed client may write; writes from
+// others are ignored (since API 1.17).
 message SerialProxyWriteRequest {
   option (id) = 140;
   option (source) = SOURCE_CLIENT;
@@ -2742,7 +2775,8 @@ message SerialProxyWriteRequest {
   bytes data = 2;               // Raw data to write to the serial device
 }
 
-// Set modem control pin states (RTS and DTR)
+// Set modem control pin states (RTS and DTR). Only the subscribed client may set them;
+// others are refused with PORT_IN_USE (since API 1.17).
 message SerialProxySetModemPinsRequest {
   option (id) = 141;
   option (source) = SOURCE_CLIENT;
@@ -2769,12 +2803,19 @@ message SerialProxyGetModemPinsResponse {
 
   uint32 instance = 1;          // Instance index (0-based)
   uint32 line_states = 2;       // Bitmask of SerialProxyLineStateFlags
+  SerialProxyStatus status = 3; // INVALID_ARGUMENT if the instance index is out of range (since API 1.16)
 }
 
 enum SerialProxyRequestType {
   SERIAL_PROXY_REQUEST_TYPE_SUBSCRIBE = 0;   // Subscribe to receive data from this serial proxy instance
   SERIAL_PROXY_REQUEST_TYPE_UNSUBSCRIBE = 1; // Unsubscribe from this serial proxy instance
   SERIAL_PROXY_REQUEST_TYPE_FLUSH = 2;       // Flush the serial port (block until all TX data is sent)
+  // Values below are only valid in SerialProxyRequestResponse.type, identifying which
+  // operation is being acknowledged. Sending them in SerialProxyRequest.type is an
+  // error the device answers with INVALID_ARGUMENT.
+  SERIAL_PROXY_REQUEST_TYPE_CONFIGURE = 3;      // Acknowledges a SerialProxyConfigureRequest
+  SERIAL_PROXY_REQUEST_TYPE_SET_MODEM_PINS = 4; // Acknowledges a SerialProxySetModemPinsRequest
+  SERIAL_PROXY_REQUEST_TYPE_SET_MODE = 5;       // Acknowledges a SerialProxySetModeRequest (since API 1.17)
 }
 
 enum SerialProxyStatus {
@@ -2783,9 +2824,12 @@ enum SerialProxyStatus {
   SERIAL_PROXY_STATUS_ERROR = 2;           // Driver or hardware error
   SERIAL_PROXY_STATUS_TIMEOUT = 3;         // Timed out before TX completed
   SERIAL_PROXY_STATUS_NOT_SUPPORTED = 4;   // Request type not supported by this instance
+  SERIAL_PROXY_STATUS_PORT_IN_USE = 5;     // Denied: another client holds the port
+  SERIAL_PROXY_STATUS_INVALID_ARGUMENT = 6; // Invalid instance index or parameter value
 }
 
-// Generic request message for simple serial proxy operations
+// Generic request message for simple serial proxy operations. FLUSH requires an active
+// subscription; it is refused with PORT_IN_USE otherwise (since API 1.17).
 message SerialProxyRequest {
   option (id) = 144;
   option (source) = SOURCE_CLIENT;
@@ -2795,7 +2839,9 @@ message SerialProxyRequest {
   SerialProxyRequestType type = 2;      // Request type
 }
 
-// Response to a SerialProxyRequest (e.g. flush completion or failure)
+// Acknowledges a serial proxy operation; the type field identifies which
+// operation is being acknowledged. Flush has been acknowledged since the
+// message was introduced; all other acknowledgements are sent since API 1.16.
 message SerialProxyRequestResponse {
   option (id) = 147;
   option (source) = SOURCE_SERVER;
@@ -2807,6 +2853,29 @@ message SerialProxyRequestResponse {
   string error_message = 4;            // Additional detail on failure (optional)
 }
 
+// How a port treats the bytes passing through it. RAW is a plain byte pipe; PROTOCOL
+// activates the port's protocol-aware tap (if one is configured), letting it observe
+// traffic and inject protocol bytes such as acknowledgements. Which protocol the tap
+// speaks is a property of the device configuration, discoverable from the tap
+// component's own API surface. A client that is about to flash firmware selects RAW
+// first, which definitively disables that injection.
+enum SerialProxyMode {
+  SERIAL_PROXY_MODE_RAW = 0;
+  SERIAL_PROXY_MODE_PROTOCOL = 1;
+}
+
+// Only the subscribed client may change the mode; any other caller -- including one that
+// never subscribed -- is refused with PORT_IN_USE. PROTOCOL is refused with NOT_SUPPORTED
+// when the port has no protocol-aware tap configured.
+message SerialProxySetModeRequest {
+  option (id) = 152;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;
+  SerialProxyMode mode = 2;
+}
+
 // ==================== BLUETOOTH CONNECTION PARAMS ====================
 message BluetoothSetConnectionParamsRequest {
   option (id) = 145;

esphome/components/api/api_buffer.cpp

@@ -1,13 +1,37 @@
 #include "api_buffer.h"
+#ifdef ESPHOME_DEBUG_API
+#include "esphome/core/log.h"
+#endif
 
 namespace esphome::api {
 
-void APIBuffer::grow_(size_t n) {
-  auto new_data = make_buffer(n);
-  if (this->size_)
-    std::memcpy(new_data.get(), this->data_.get(), this->size_);
-  this->data_ = std::move(new_data);
+#ifdef ESPHOME_DEBUG_API
+void APIBuffer::debug_check_drop_(size_t drop) const {
+  if (drop > this->size_) {
+    ESP_LOGE("api.buffer", "drop_front: drop=%zu size=%u", drop, this->size_);
+    abort();
+  }
+}
+#endif
+
+bool APIBuffer::grow_(size_t n) {
+  if (n > MAX_SIZE)
+    return false;
+  // realloc extends in place when it can, avoiding the copy
+  uint8_t *grown = RAMAllocator<uint8_t>().reallocate(this->data_.get(), n);
+  if (grown == nullptr)
+    return false;
+  (void) this->data_.release();  // realloc already freed or reused the old block
+  this->data_.reset(grown);
   this->capacity_ = n;
+  return true;
+}
+
+uint8_t *APIBuffer::append(size_t n) {
+  const size_t old_size = this->size_;
+  if (!this->resize(old_size + n))
+    return nullptr;
+  return this->data_.get() + old_size;
 }
 
 }  // namespace esphome::api

esphome/components/api/api_buffer.h

@@ -9,16 +9,6 @@
 
 namespace esphome::api {
 
-/// Helper to use make_unique_for_overwrite where available (skips zero-fill),
-/// falling back to make_unique on older GCC (ESP8266, LibreTiny).
-inline std::unique_ptr<uint8_t[]> make_buffer(size_t n) {
-#if defined(USE_ESP8266) || defined(USE_LIBRETINY)
-  return std::make_unique<uint8_t[]>(n);
-#else
-  return std::make_unique_for_overwrite<uint8_t[]>(n);
-#endif
-}
-
 /// Byte buffer that skips zero-initialization on resize().
 ///
 /// std::vector<uint8_t>::resize() zero-fills new bytes via memset. For the
@@ -35,24 +25,35 @@ inline std::unique_ptr<uint8_t[]> make_buffer(size_t n) {
 /// writes in debug builds.
 class APIBuffer {
  public:
+  static constexpr size_t MAX_SIZE = UINT16_MAX;  // API frames carry 16 bit lengths
   void clear() { this->size_ = 0; }
-  inline void reserve(size_t n) ESPHOME_ALWAYS_INLINE {
-    if (n > this->capacity_)
-      this->grow_(n);
-  }
-  inline void resize(size_t n) ESPHOME_ALWAYS_INLINE {
-    this->reserve(n);
-    this->size_ = n;  // no zero-fill
-  }
+  /// Returns false if allocation fails; the buffer is left unchanged.
+  [[nodiscard]] inline bool reserve(size_t n) ESPHOME_ALWAYS_INLINE { return n <= this->capacity_ || this->grow_(n); }
+  /// Returns false if allocation fails; the buffer is left unchanged. No zero-fill.
+  [[nodiscard]] inline bool resize(size_t n) ESPHOME_ALWAYS_INLINE { return this->reserve_and_resize(n, n); }
   /// Reserve capacity for max(reserve_size, new_size) bytes, then set size to new_size.
   /// Single grow_ check regardless of argument order.
-  inline void reserve_and_resize(size_t reserve_size, size_t new_size) ESPHOME_ALWAYS_INLINE {
-    this->reserve(std::max(reserve_size, new_size));
-    this->size_ = new_size;
+  /// Returns false if allocation fails; the buffer is left unchanged.
+  [[nodiscard]] inline bool reserve_and_resize(size_t reserve_size, size_t new_size) ESPHOME_ALWAYS_INLINE {
+    if (!this->reserve(std::max(reserve_size, new_size)))
+      return false;
+    this->size_ = static_cast<uint16_t>(new_size);
+    return true;
+  }
+  /// Grow by n bytes; returns the new bytes, or nullptr on allocation failure.
+  [[nodiscard]] uint8_t *append(size_t n);
+  /// Drop the first `drop` bytes, sliding the rest down. Precondition: drop <= size().
+  void drop_front(size_t drop) {
+#ifdef ESPHOME_DEBUG_API
+    this->debug_check_drop_(drop);
+#endif
+    this->size_ -= drop;
+    std::memmove(this->data_.get(), this->data_.get() + drop, this->size_);
   }
   uint8_t *data() { return this->data_.get(); }
   const uint8_t *data() const { return this->data_.get(); }
   size_t size() const { return this->size_; }
+  size_t capacity() const { return this->capacity_; }
   bool empty() const { return this->size_ == 0; }
   uint8_t &operator[](size_t i) { return this->data_[i]; }
   const uint8_t &operator[](size_t i) const { return this->data_[i]; }
@@ -64,10 +65,15 @@ class APIBuffer {
   }
 
  protected:
-  void grow_(size_t n);
-  std::unique_ptr<uint8_t[]> data_;
-  size_t size_{0};
-  size_t capacity_{0};
+  bool grow_(size_t n);
+#ifdef ESPHOME_DEBUG_API
+  void debug_check_drop_(size_t drop) const;
+#endif
+  // RAMAllocator: PSRAM when available, and it reports failure where
+  // new (std::nothrow) still aborts on ESP-IDF without exceptions
+  RAMUniquePtr<uint8_t[]> data_;
+  uint16_t size_{0};
+  uint16_t capacity_{0};
 };
 
 }  // namespace esphome::api

esphome/components/api/api_connection.cpp

@@ -1,6 +1,6 @@
 #include "api_connection.h"
 #ifdef USE_API
-#include "api_connection_buffer.h"  // for encode_to_buffer / get_batch_delay_ms_ inlines
+#include "api_connection_buffer.h"  // for the APIServer-dependent APIConnection inlines
 #ifdef USE_API_NOISE
 #include "api_frame_helper_noise.h"
 #endif
@@ -364,7 +364,10 @@ void APIConnection::check_keepalive_(uint32_t now) {
     ESP_LOGVV(TAG, "Sending keepalive PING");
     PingRequest req;
     this->flags_.sent_ping = this->send_message(req);
-    if (!this->flags_.sent_ping) {
+    if (this->flags_.sent_ping) {
+      // Quiet for a keepalive period and the ping is on its way: a one-off stall's storage can go
+      this->helper_->release_overflow_buffer();
+    } else {
       // If we can't send the ping request directly (tx_buffer full),
       // schedule it at the front of the batch so it will be sent with priority
       ESP_LOGW(TAG, "Buffer full, ping queued");
@@ -597,7 +600,7 @@ bool APIConnection::send_light_state(light::LightState *light) {
 uint16_t APIConnection::try_send_light_state(EntityBase *entity, APIConnection *conn, uint32_t remaining_size) {
   auto *light = static_cast<light::LightState *>(entity);
   LightStateResponse resp;
-  auto values = light->remote_values;
+  auto values = light->get_reported_values();
   auto color_mode = values.get_color_mode();
   resp.state = values.is_on();
   resp.color_mode = static_cast<enums::ColorMode>(color_mode);
@@ -706,6 +709,7 @@ uint16_t APIConnection::try_send_switch_state(EntityBase *entity, APIConnection
   auto *a_switch = static_cast<switch_::Switch *>(entity);
   SwitchStateResponse resp;
   resp.state = a_switch->state;
+  resp.missing_state = !a_switch->has_state();
   return fill_and_encode_entity_state(a_switch, resp, conn, remaining_size);
 }
 
@@ -717,12 +721,7 @@ uint16_t APIConnection::try_send_switch_info(EntityBase *entity, APIConnection *
 }
 void APIConnection::on_switch_command_request(const SwitchCommandRequest &msg) {
   ENTITY_COMMAND_GET(switch_::Switch, a_switch, switch)
-
-  if (msg.state) {
-    a_switch->turn_on();
-  } else {
-    a_switch->turn_off();
-  }
+  a_switch->control(msg.state);
 }
 #endif
 
@@ -756,6 +755,7 @@ uint16_t APIConnection::try_send_climate_state(EntityBase *entity, APIConnection
   auto traits = climate->get_traits();
   resp.mode = static_cast<enums::ClimateMode>(climate->mode);
   resp.action = static_cast<enums::ClimateAction>(climate->action);
+  resp.missing_state = !climate->has_state();
   if (traits.has_feature_flags(climate::CLIMATE_SUPPORTS_CURRENT_TEMPERATURE))
     resp.current_temperature = climate->current_temperature;
   if (traits.has_feature_flags(climate::CLIMATE_SUPPORTS_TWO_POINT_TARGET_TEMPERATURE |
@@ -1099,7 +1099,6 @@ uint16_t APIConnection::try_send_media_player_info(EntityBase *entity, APIConnec
   auto *media_player = static_cast<media_player::MediaPlayer *>(entity);
   ListEntitiesMediaPlayerResponse msg;
   auto traits = media_player->get_traits();
-  msg.supports_pause = traits.get_supports_pause();
   msg.feature_flags = traits.get_feature_flags();
   for (auto &supported_format : traits.get_supported_formats()) {
     msg.supported_formats.emplace_back();
@@ -1381,7 +1380,12 @@ void APIConnection::on_z_wave_proxy_frame(const ZWaveProxyFrame &msg) {
 }
 
 void APIConnection::on_z_wave_proxy_request(const ZWaveProxyRequest &msg) {
-  zwave_proxy::global_zwave_proxy->zwave_proxy_request(this, msg.type);
+  ZWaveProxyRequestResponse resp{};
+  resp.type = msg.type;
+  resp.status = zwave_proxy::global_zwave_proxy->zwave_proxy_request(this, msg.type);
+  if (!this->send_message(resp)) {
+    API_LOG_MSG_DROPPED(TAG, "Z-Wave proxy response");
+  }
 }
 #endif
 
@@ -1445,6 +1449,7 @@ uint16_t APIConnection::try_send_water_heater_state(EntityBase *entity, APIConne
   auto *wh = static_cast<water_heater::WaterHeater *>(entity);
   WaterHeaterStateResponse resp;
   resp.mode = static_cast<enums::WaterHeaterMode>(wh->get_mode());
+  resp.missing_state = !wh->has_state();
   resp.current_temperature = wh->get_current_temperature();
   resp.target_temperature = wh->get_target_temperature();
   resp.target_temperature_low = wh->get_target_temperature_low();
@@ -1550,15 +1555,50 @@ void APIConnection::send_infrared_rf_receive_event(const InfraredRFReceiveEvent
 #endif
 
 #ifdef USE_SERIAL_PROXY
+static enums::SerialProxyStatus serial_proxy_result_to_status(serial_proxy::SerialProxyResult result) {
+  switch (result) {
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_OK:
+      return enums::SERIAL_PROXY_STATUS_OK;
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_ASSUMED_SUCCESS:
+      return enums::SERIAL_PROXY_STATUS_ASSUMED_SUCCESS;
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_PORT_IN_USE:
+      return enums::SERIAL_PROXY_STATUS_PORT_IN_USE;
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_INVALID_ARGUMENT:
+      return enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT;
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_TIMEOUT:
+      return enums::SERIAL_PROXY_STATUS_TIMEOUT;
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_NOT_SUPPORTED:
+      return enums::SERIAL_PROXY_STATUS_NOT_SUPPORTED;
+    case serial_proxy::SerialProxyResult::SERIAL_PROXY_RESULT_ERROR:
+      return enums::SERIAL_PROXY_STATUS_ERROR;
+  }
+  return enums::SERIAL_PROXY_STATUS_ERROR;  // Unreachable; all enum values handled above
+}
+
+static void send_serial_proxy_ack(APIConnection *conn, uint32_t instance, enums::SerialProxyRequestType type,
+                                  enums::SerialProxyStatus status) {
+  SerialProxyRequestResponse resp{};
+  resp.instance = instance;
+  resp.type = type;
+  resp.status = status;
+  if (!conn->send_message(resp)) {
+    API_LOG_MSG_DROPPED(TAG, "Serial proxy response");
+  }
+}
+
 void APIConnection::on_serial_proxy_configure_request(const SerialProxyConfigureRequest &msg) {
   auto &proxies = App.get_serial_proxies();
   if (msg.instance >= proxies.size()) {
     ESP_LOGW(TAG, "Serial proxy instance %" PRIu32 " out of range (max %" PRIu32 ")", msg.instance,
              static_cast<uint32_t>(proxies.size()));
+    send_serial_proxy_ack(this, msg.instance, enums::SERIAL_PROXY_REQUEST_TYPE_CONFIGURE,
+                          enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT);
     return;
   }
-  proxies[msg.instance]->configure(this, msg.baudrate, msg.flow_control, static_cast<uint8_t>(msg.parity),
-                                   msg.stop_bits, msg.data_size);
+  serial_proxy::SerialProxyResult result = proxies[msg.instance]->configure(
+      this, msg.baudrate, msg.flow_control, static_cast<uint8_t>(msg.parity), msg.stop_bits, msg.data_size);
+  send_serial_proxy_ack(this, msg.instance, enums::SERIAL_PROXY_REQUEST_TYPE_CONFIGURE,
+                        serial_proxy_result_to_status(result));
 }
 
 void APIConnection::on_serial_proxy_write_request(const SerialProxyWriteRequest &msg) {
@@ -1574,20 +1614,30 @@ void APIConnection::on_serial_proxy_set_modem_pins_request(const SerialProxySetM
   auto &proxies = App.get_serial_proxies();
   if (msg.instance >= proxies.size()) {
     ESP_LOGW(TAG, "Serial proxy instance %" PRIu32 " out of range", msg.instance);
+    send_serial_proxy_ack(this, msg.instance, enums::SERIAL_PROXY_REQUEST_TYPE_SET_MODEM_PINS,
+                          enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT);
     return;
   }
-  proxies[msg.instance]->set_modem_pins(this, msg.line_states);
+  serial_proxy::SerialProxyResult result = proxies[msg.instance]->set_modem_pins(this, msg.line_states);
+  send_serial_proxy_ack(this, msg.instance, enums::SERIAL_PROXY_REQUEST_TYPE_SET_MODEM_PINS,
+                        serial_proxy_result_to_status(result));
 }
 
 void APIConnection::on_serial_proxy_get_modem_pins_request(const SerialProxyGetModemPinsRequest &msg) {
   auto &proxies = App.get_serial_proxies();
-  if (msg.instance >= proxies.size()) {
-    ESP_LOGW(TAG, "Serial proxy instance %" PRIu32 " out of range", msg.instance);
-    return;
-  }
   SerialProxyGetModemPinsResponse resp{};
   resp.instance = msg.instance;
-  resp.line_states = proxies[msg.instance]->get_modem_pins();
+  if (msg.instance >= proxies.size()) {
+    ESP_LOGW(TAG, "Serial proxy instance %" PRIu32 " out of range", msg.instance);
+    // Pre-1.16 clients do not read the status field and would take this error
+    // for a successful "both pins deasserted" answer; let them time out as before
+    if (!this->client_supports_api_version(1, 16)) {
+      return;
+    }
+    resp.status = enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT;
+  } else {
+    resp.line_states = proxies[msg.instance]->get_modem_pins();
+  }
   if (!this->send_message(resp)) {
     API_LOG_MSG_DROPPED(TAG, "Serial proxy response");
   }
@@ -1597,40 +1647,45 @@ void APIConnection::on_serial_proxy_request(const SerialProxyRequest &msg) {
   auto &proxies = App.get_serial_proxies();
   if (msg.instance >= proxies.size()) {
     ESP_LOGW(TAG, "Serial proxy instance %" PRIu32 " out of range", msg.instance);
+    send_serial_proxy_ack(this, msg.instance, msg.type, enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT);
     return;
   }
+  auto *proxy = proxies[msg.instance];
+  enums::SerialProxyStatus status;
   switch (msg.type) {
     case enums::SERIAL_PROXY_REQUEST_TYPE_SUBSCRIBE:
     case enums::SERIAL_PROXY_REQUEST_TYPE_UNSUBSCRIBE:
-      proxies[msg.instance]->serial_proxy_request(this, msg.type);
+      status = serial_proxy_result_to_status(proxy->serial_proxy_request(this, msg.type));
       break;
-    case enums::SERIAL_PROXY_REQUEST_TYPE_FLUSH: {
-      SerialProxyRequestResponse resp{};
-      resp.instance = msg.instance;
-      resp.type = enums::SERIAL_PROXY_REQUEST_TYPE_FLUSH;
-      switch (proxies[msg.instance]->flush_port()) {
-        case uart::UARTFlushResult::UART_FLUSH_RESULT_SUCCESS:
-          resp.status = enums::SERIAL_PROXY_STATUS_OK;
-          break;
-        case uart::UARTFlushResult::UART_FLUSH_RESULT_ASSUMED_SUCCESS:
-          resp.status = enums::SERIAL_PROXY_STATUS_ASSUMED_SUCCESS;
-          break;
-        case uart::UARTFlushResult::UART_FLUSH_RESULT_TIMEOUT:
-          resp.status = enums::SERIAL_PROXY_STATUS_TIMEOUT;
-          break;
-        case uart::UARTFlushResult::UART_FLUSH_RESULT_FAILED:
-          resp.status = enums::SERIAL_PROXY_STATUS_ERROR;
-          break;
-      }
-      if (!this->send_message(resp)) {
-        API_LOG_MSG_DROPPED(TAG, "Serial proxy response");
-      }
+    case enums::SERIAL_PROXY_REQUEST_TYPE_FLUSH:
+      status = serial_proxy_result_to_status(proxy->flush_port(this));
+      break;
+    case enums::SERIAL_PROXY_REQUEST_TYPE_CONFIGURE:
+    case enums::SERIAL_PROXY_REQUEST_TYPE_SET_MODEM_PINS:
+    case enums::SERIAL_PROXY_REQUEST_TYPE_SET_MODE:
+      // Response-only discriminators; never valid in a request
+      ESP_LOGW(TAG, "Response-only serial proxy request type: %" PRIu32, static_cast<uint32_t>(msg.type));
+      status = enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT;
       break;
-    }
     default:
       ESP_LOGW(TAG, "Unknown serial proxy request type: %" PRIu32, static_cast<uint32_t>(msg.type));
+      status = enums::SERIAL_PROXY_STATUS_NOT_SUPPORTED;
       break;
   }
+  send_serial_proxy_ack(this, msg.instance, msg.type, status);
+}
+
+void APIConnection::on_serial_proxy_set_mode_request(const SerialProxySetModeRequest &msg) {
+  auto &proxies = App.get_serial_proxies();
+  if (msg.instance >= proxies.size()) {
+    ESP_LOGW(TAG, "Serial proxy instance %" PRIu32 " out of range", msg.instance);
+    send_serial_proxy_ack(this, msg.instance, enums::SERIAL_PROXY_REQUEST_TYPE_SET_MODE,
+                          enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT);
+    return;
+  }
+  serial_proxy::SerialProxyResult result = proxies[msg.instance]->set_mode_from_client(this, msg.mode);
+  send_serial_proxy_ack(this, msg.instance, enums::SERIAL_PROXY_REQUEST_TYPE_SET_MODE,
+                        serial_proxy_result_to_status(result));
 }
 
 void APIConnection::send_serial_proxy_data(const SerialProxyDataReceived &msg) {
@@ -1749,15 +1804,17 @@ void APIConnection::complete_authentication_() {
 bool APIConnection::send_hello_response_(const HelloRequest &msg) {
   // Copy client name with truncation if needed (set_client_name handles truncation)
   this->helper_->set_client_name(msg.client_info.c_str(), msg.client_info.size());
-  this->client_api_version_major_ = msg.api_version_major;
-  this->client_api_version_minor_ = msg.api_version_minor;
+  this->client_api_version_major_ =
+      static_cast<uint8_t>(std::min<uint32_t>(msg.api_version_major, std::numeric_limits<uint8_t>::max()));
+  this->client_api_version_minor_ =
+      static_cast<uint8_t>(std::min<uint32_t>(msg.api_version_minor, std::numeric_limits<uint8_t>::max()));
   char peername[socket::SOCKADDR_STR_LEN];
-  ESP_LOGV(TAG, "Hello from client: '%s' | %s | API Version %" PRIu16 ".%" PRIu16, this->helper_->get_client_name(),
+  ESP_LOGV(TAG, "Hello from client: '%s' | %s | API Version %u.%u", this->helper_->get_client_name(),
            this->helper_->get_peername_to(peername), this->client_api_version_major_, this->client_api_version_minor_);
 
   HelloResponse resp;
   resp.api_version_major = 1;
-  resp.api_version_minor = 15;
+  resp.api_version_minor = 17;
   // Send only the version string - the client only logs this for debugging and doesn't use it otherwise
   resp.server_info = ESPHOME_VERSION_REF;
   resp.name = StringRef(App.get_name());
@@ -1891,6 +1948,7 @@ bool APIConnection::send_device_info_response_() {
     auto &info = resp.serial_proxies[serial_proxy_index++];
     info.name = StringRef(proxy->get_name());
     info.port_type = proxy->get_port_type();
+    info.configured_line_states = proxy->get_configured_modem_pins();
   }
 #endif
 #ifdef USE_API_NOISE
@@ -1951,6 +2009,7 @@ bool APIConnection::send_device_capabilities_response_() {
     auto &info = resp.serial_proxies[serial_proxy_index++];
     info.name = StringRef(proxy->get_name());
     info.port_type = proxy->get_port_type();
+    info.configured_line_states = proxy->get_configured_modem_pins();
   }
 #endif
   return this->send_message(resp);
@@ -2117,7 +2176,10 @@ void APIConnection::on_homeassistant_action_response(const HomeassistantActionRe
 bool APIConnection::send_noise_encryption_set_key_response_(const NoiseEncryptionSetKeyRequest &msg) {
   NoiseEncryptionSetKeyResponse resp;
   resp.success = false;
-
+#ifdef USE_API_NOISE_PSK_FROM_YAML
+  // A yaml key cannot be changed at runtime, so no decode or save path is built
+  ESP_LOGW(TAG, "Key set in YAML");
+#else
 #ifdef USE_PROVISIONING
   // Refuse to set a key once the provisioning window has closed (defense in depth;
   // such connections are already rejected at hello).
@@ -2152,6 +2214,7 @@ bool APIConnection::send_noise_encryption_set_key_response_(const NoiseEncryptio
     }
 #endif
   }
+#endif  // USE_API_NOISE_PSK_FROM_YAML
 
   return this->send_message(resp);
 }
@@ -2181,7 +2244,7 @@ bool APIConnection::try_to_clear_buffer_slow_(bool log_out_of_space) {
   }
   return false;
 }
-bool APIConnection::send_message_(uint32_t payload_size, uint8_t message_type, MessageEncodeFn encode_fn,
+bool APIConnection::send_message_(uint32_t payload_size, uint16_t message_type, MessageEncodeFn encode_fn,
                                   const void *msg) {
 #ifdef HAS_PROTO_MESSAGE_DUMP
   // Skip dump for log messages (recursive logging risk) and camera frames (high-frequency noise)
@@ -2195,12 +2258,24 @@ bool APIConnection::send_message_(uint32_t payload_size, uint8_t message_type, M
     this->log_send_message_(proto_msg->message_name(), proto_msg->dump_to(dump_buf));
   }
 #endif
+  if (!this->prepare_first_message_buffer(payload_size)) [[unlikely]] {
+    this->fatal_out_of_memory_();
+    return false;
+  }
   auto &shared_buf = this->parent_->get_shared_buffer_ref();
-  this->prepare_first_message_buffer(shared_buf, payload_size);
   size_t write_start = shared_buf.size();
-  shared_buf.resize(write_start + payload_size);
+#ifdef ESPHOME_DEBUG_API
+  assert(shared_buf.capacity() >= write_start + payload_size);
+#endif
+  // Capacity reserved above, cannot fail
+  (void) shared_buf.resize(write_start + payload_size);
   ProtoWriteBuffer buffer{&shared_buf, write_start};
-  encode_fn(msg, buffer PROTO_ENCODE_DEBUG_INIT(&shared_buf));
+  uint8_t *end = encode_fn(msg, buffer PROTO_ENCODE_DEBUG_INIT(&shared_buf));
+#ifdef ESPHOME_DEBUG_API
+  proto_check_encode_end(end, shared_buf.data() + shared_buf.size());
+#else
+  (void) end;
+#endif
   return this->send_buffer(ProtoWriteBuffer{&shared_buf}, message_type);
 }
 // encode_to_buffer is defined inline in api_connection.h (ESPHOME_ALWAYS_INLINE)
@@ -2210,7 +2285,7 @@ uint16_t APIConnection::encode_to_buffer_slow(uint32_t calculated_size, MessageE
                                               APIConnection *conn, uint32_t remaining_size) {
   return encode_to_buffer(calculated_size, encode_fn, msg, conn, remaining_size);
 }
-bool APIConnection::send_buffer(ProtoWriteBuffer buffer, uint8_t message_type) {
+bool APIConnection::send_buffer(ProtoWriteBuffer buffer, uint16_t message_type) {
   const bool is_log_message = (message_type == SubscribeLogsResponse::MESSAGE_TYPE);
 
   if (!this->try_to_clear_buffer(!is_log_message)) {
@@ -2234,30 +2309,42 @@ void APIConnection::on_no_setup_connection() {
   this->on_fatal_error();
   this->log_client_(ESPHOME_LOG_LEVEL_DEBUG, LOG_STR("no connection setup"));
 }
+void APIConnection::fatal_out_of_memory_() {
+  this->fatal_error_with_log_(LOG_STR("Out of memory"), APIError::OUT_OF_MEMORY);
+}
 void APIConnection::on_fatal_error() {
   // Don't close socket here - keep it open so getpeername() works for logging
   // Socket will be closed when client is removed from the list in APIServer::loop()
   this->flags_.remove = true;
 }
 
-bool APIConnection::schedule_message_front_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size) {
+bool APIConnection::schedule_message_front_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size) {
   this->deferred_batch_.add_item_front(entity, message_type, estimated_size);
   return this->schedule_batch_();
 }
 
-bool APIConnection::send_message_smart_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
+bool APIConnection::send_message_smart_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size,
                                         uint8_t aux_data_index) {
   if (this->should_send_immediately_(message_type) && this->helper_->can_write_without_blocking()) {
-    auto &shared_buf = this->parent_->get_shared_buffer_ref();
-    this->prepare_first_message_buffer(shared_buf, estimated_size);
+    // No local for the shared buffer here: keeping it live across
+    // dispatch_message_ costs a register and spills message_type into the
+    // batching path's dedup loop (measured on x86 GCC -Os)
+    if (!this->prepare_first_message_buffer(estimated_size)) [[unlikely]] {
+      this->fatal_out_of_memory_();
+      return false;
+    }
     DeferredBatch::BatchItem item{entity, message_type, estimated_size, aux_data_index};
     if (this->dispatch_message_(item, MAX_BATCH_PACKET_SIZE, true) &&
-        this->send_buffer(ProtoWriteBuffer{&shared_buf}, message_type)) {
+        this->send_buffer(ProtoWriteBuffer{&this->parent_->get_shared_buffer_ref()}, message_type)) {
 #ifdef HAS_PROTO_MESSAGE_DUMP
       this->log_batch_item_(item);
 #endif
       return true;
     }
+    // An OOM during the immediate attempt marks the connection for removal;
+    // don't queue more work (schedule_message_'s push_back may allocate again)
+    if (this->flags_.remove) [[unlikely]]
+      return false;
   }
   return this->schedule_message_(entity, message_type, estimated_size, aux_data_index);
 }
@@ -2307,7 +2394,11 @@ void APIConnection::process_batch_() {
     total_estimated_size = MAX_BATCH_PACKET_SIZE;
   }
 
-  this->prepare_first_message_buffer(shared_buf, header_padding, total_estimated_size);
+  if (!this->prepare_first_message_buffer(header_padding, total_estimated_size)) [[unlikely]] {
+    this->fatal_out_of_memory_();
+    this->clear_batch_();
+    return;
+  }
 
   // Fast path for single message - buffer already allocated above
   if (num_items == 1) {
@@ -2322,8 +2413,11 @@ void APIConnection::process_batch_() {
 #endif
       this->clear_batch_();
     } else if (payload_size == 0) {
-      // Message too large to fit in available space
-      ESP_LOGW(TAG, "Message too large to send: type=%u", item.message_type);
+      // payload_size == 0 with remove set means encoding hit OOM and the
+      // connection is being dropped; warn only for a genuinely oversized message
+      if (!this->flags_.remove) {
+        ESP_LOGW(TAG, "Message too large to send: type=%u", item.message_type);
+      }
       this->clear_batch_();
     }
     return;
@@ -2386,8 +2480,10 @@ void APIConnection::process_batch_multi_(APIBuffer &shared_buf, size_t num_items
 
   if (items_processed > 0) {
     // Add footer space for the last message (for Noise protocol MAC)
-    if (footer_size > 0) {
-      shared_buf.resize(shared_buf.size() + footer_size);
+    if (footer_size > 0 && !shared_buf.resize(shared_buf.size() + footer_size)) [[unlikely]] {
+      this->fatal_out_of_memory_();
+      this->clear_batch_();
+      return;
     }
 
     // Send all collected messages

esphome/components/api/api_connection.h

@@ -244,6 +244,7 @@ class APIConnection final : public APIServerConnectionBase {
   void on_serial_proxy_set_modem_pins_request(const SerialProxySetModemPinsRequest &msg);
   void on_serial_proxy_get_modem_pins_request(const SerialProxyGetModemPinsRequest &msg);
   void on_serial_proxy_request(const SerialProxyRequest &msg);
+  void on_serial_proxy_set_mode_request(const SerialProxySetModeRequest &msg);
   void send_serial_proxy_data(const SerialProxyDataReceived &msg);
 #endif
 
@@ -326,8 +327,10 @@ class APIConnection final : public APIServerConnectionBase {
   bool is_marked_for_removal() const { return this->flags_.remove; }
   uint8_t get_log_subscription_level() const { return this->flags_.log_subscription; }
 
-  // Get client API version for feature detection
-  bool client_supports_api_version(uint16_t major, uint16_t minor) const {
+  // Get client API version for feature detection.
+  // Stored versions saturate at 255 (see send_hello_response_), so requesting
+  // a minimum above that can never match.
+  bool client_supports_api_version(uint8_t major, uint8_t minor) const {
     return this->client_api_version_major_ > major ||
            (this->client_api_version_major_ == major && this->client_api_version_minor_ >= minor);
   }
@@ -343,29 +346,16 @@ class APIConnection final : public APIServerConnectionBase {
   /// Returns false as soon as the TCP buffer is full. Marked nodiscard so we
   /// have no silent failures: every caller must handle (or log) a refusal.
   template<typename T> [[nodiscard]] bool send_message(const T &msg) {
-    if constexpr (T::ESTIMATED_SIZE == 0) {
-      return this->send_message_(0, T::MESSAGE_TYPE, &encode_msg_noop, &msg);
-    } else {
-      return this->send_message_(msg.calculate_size(), T::MESSAGE_TYPE, &proto_encode_msg<T>, &msg);
-    }
+    return this->send_message_(T::calc_size_msg(&msg), T::MESSAGE_TYPE, &T::encode_msg, &msg);
   }
 
-  void prepare_first_message_buffer(APIBuffer &shared_buf, size_t header_padding, size_t total_size) {
-    shared_buf.clear();
-    // Reserve space for header padding + message + footer
-    // - Header padding: space for protocol headers (7 bytes for Noise, 6 for Plaintext)
-    // - Footer: space for MAC (16 bytes for Noise, 0 for Plaintext)
-    // Reserve full size but only set initial size to header padding
-    // so message encoding starts at the correct position
-    shared_buf.reserve_and_resize(total_size, header_padding);
-  }
+  /// Clear the shared write buffer and reserve space for the first message.
+  /// Returns false if the allocation fails (out of memory).
+  /// Defined in api_connection_buffer.h (needs APIServer complete).
+  [[nodiscard]] bool prepare_first_message_buffer(size_t header_padding, size_t total_size);
 
   // Convenience overload - computes frame overhead internally
-  void prepare_first_message_buffer(APIBuffer &shared_buf, size_t payload_size) {
-    const uint8_t header_padding = this->helper_->frame_header_padding();
-    const uint8_t footer_size = this->helper_->frame_footer_size();
-    this->prepare_first_message_buffer(shared_buf, header_padding, payload_size + header_padding + footer_size);
-  }
+  [[nodiscard]] bool prepare_first_message_buffer(size_t payload_size);
 
   bool try_to_clear_buffer(bool log_out_of_space) {
     if (this->flags_.remove)
@@ -374,7 +364,7 @@ class APIConnection final : public APIServerConnectionBase {
       return true;
     return this->try_to_clear_buffer_slow_(log_out_of_space);
   }
-  bool send_buffer(ProtoWriteBuffer buffer, uint8_t message_type);
+  bool send_buffer(ProtoWriteBuffer buffer, uint16_t message_type);
 
   const char *get_name() const { return this->helper_->get_client_name(); }
   /// Get peer name (IP address) into caller-provided buffer, returns buf for convenience
@@ -412,18 +402,8 @@ class APIConnection final : public APIServerConnectionBase {
   void process_state_subscriptions_();
 #endif
 
-  // Size thunk — converts void* back to concrete type for direct calculate_size() call
-  template<typename T> static uint32_t calc_size(const void *msg) {
-    return static_cast<const T *>(msg)->calculate_size();
-  }
-
-  // Shared no-op encode thunk for empty messages (ESTIMATED_SIZE == 0)
-  static uint8_t *encode_msg_noop(const void *, ProtoWriteBuffer &buf PROTO_ENCODE_DEBUG_PARAM) {
-    return buf.get_pos();
-  }
-
   // Non-template buffer management for send_message
-  bool send_message_(uint32_t payload_size, uint8_t message_type, MessageEncodeFn encode_fn, const void *msg);
+  bool send_message_(uint32_t payload_size, uint16_t message_type, MessageEncodeFn encode_fn, const void *msg);
 
   // Core batch encoding logic. ALWAYS_INLINE so encode_fn devirtualizes at hot call sites.
   // Defined in api_connection_buffer.h (needs APIServer complete).
@@ -440,11 +420,7 @@ class APIConnection final : public APIServerConnectionBase {
   // Hot paths (state/info) go through fill_and_encode_entity_state/info instead.
   // batch_message_type_ is already set by dispatch_message_ before reaching here.
   template<typename T> static uint16_t encode_message_to_buffer(T &msg, APIConnection *conn, uint32_t remaining_size) {
-    if constexpr (T::ESTIMATED_SIZE == 0) {
-      return encode_to_buffer_slow(0, &encode_msg_noop, &msg, conn, remaining_size);
-    } else {
-      return encode_to_buffer_slow(msg.calculate_size(), &proto_encode_msg<T>, &msg, conn, remaining_size);
-    }
+    return encode_to_buffer_slow(T::calc_size_msg(&msg), &T::encode_msg, &msg, conn, remaining_size);
   }
 
   // Non-template core — fills state fields and encodes
@@ -456,7 +432,7 @@ class APIConnection final : public APIServerConnectionBase {
   template<typename T>
   static uint16_t fill_and_encode_entity_state(EntityBase *entity, T &msg, APIConnection *conn,
                                                uint32_t remaining_size) {
-    return fill_and_encode_entity_state(entity, msg, &calc_size<T>, &proto_encode_msg<T>, conn, remaining_size);
+    return fill_and_encode_entity_state(entity, msg, &T::calc_size_msg, &T::encode_msg, conn, remaining_size);
   }
 
   // Non-template core — fills info fields, allocates buffers, and encodes
@@ -468,7 +444,7 @@ class APIConnection final : public APIServerConnectionBase {
   template<typename T>
   static uint16_t fill_and_encode_entity_info(EntityBase *entity, T &msg, APIConnection *conn,
                                               uint32_t remaining_size) {
-    return fill_and_encode_entity_info(entity, msg, &calc_size<T>, &proto_encode_msg<T>, conn, remaining_size);
+    return fill_and_encode_entity_info(entity, msg, &T::calc_size_msg, &T::encode_msg, conn, remaining_size);
   }
 
   // Non-template core — fills device_class, then delegates to fill_and_encode_entity_info
@@ -482,8 +458,8 @@ class APIConnection final : public APIServerConnectionBase {
   static uint16_t fill_and_encode_entity_info_with_device_class(EntityBase *entity, T &msg,
                                                                 StringRef &device_class_field, APIConnection *conn,
                                                                 uint32_t remaining_size) {
-    return fill_and_encode_entity_info_with_device_class(entity, msg, device_class_field, &calc_size<T>,
-                                                         &proto_encode_msg<T>, conn, remaining_size);
+    return fill_and_encode_entity_info_with_device_class(entity, msg, device_class_field, &T::calc_size_msg,
+                                                         &T::encode_msg, conn, remaining_size);
   }
 
 #ifdef USE_VOICE_ASSISTANT
@@ -664,10 +640,9 @@ class APIConnection final : public APIServerConnectionBase {
 
     struct BatchItem {
       EntityBase *entity;                       // 4 bytes - Entity pointer
-      uint8_t message_type;                     // 1 byte - Message type for protocol and dispatch
+      uint16_t message_type;                    // 2 bytes - Message type for protocol and dispatch
       uint8_t estimated_size;                   // 1 byte - Estimated message size (max 255 bytes)
       uint8_t aux_data_index{AUX_DATA_UNUSED};  // 1 byte - For events: index into entity's event_types
-      // 1 byte padding
     };
 
     std::vector<BatchItem> items;
@@ -677,7 +652,7 @@ class APIConnection final : public APIServerConnectionBase {
     // connections that do, buffers are released after initial sync anyway
 
     // Add item to the batch (with deduplication)
-    void add_item(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
+    void add_item(EntityBase *entity, uint16_t message_type, uint8_t estimated_size,
                   uint8_t aux_data_index = AUX_DATA_UNUSED) {
       // Dedup: O(n) scan but optimized for RAM over performance
       // Skip deduplication for events - they are edge-triggered, every occurrence matters
@@ -693,7 +668,7 @@ class APIConnection final : public APIServerConnectionBase {
       this->items.push_back({entity, message_type, estimated_size, aux_data_index});
     }
     // Add item to the front of the batch (for high priority messages like ping)
-    void add_item_front(EntityBase *entity, uint8_t message_type, uint8_t estimated_size) {
+    void add_item_front(EntityBase *entity, uint16_t message_type, uint8_t estimated_size) {
       // Swap to front avoids expensive vector::insert which shifts all elements
       this->items.push_back({entity, message_type, estimated_size, AUX_DATA_UNUSED});
       if (this->items.size() > 1) {
@@ -758,13 +733,15 @@ class APIConnection final : public APIServerConnectionBase {
 #endif
   } flags_{};  // 2 bytes total
 
-  // 2-byte types immediately after flags_ (no padding between them)
-  uint16_t client_api_version_major_{0};
-  uint16_t client_api_version_minor_{0};
+  // 2-byte type immediately after flags_ (no padding between them)
+  uint16_t batch_message_type_{0};  // Current message type during batch encoding
   // 1-byte types to fill remaining space before next 4-byte boundary
+  // Client API versions are clamped to 255 on receive (see send_hello_response_)
+  uint8_t client_api_version_major_{0};
+  uint8_t client_api_version_minor_{0};
   ActiveIterator active_iterator_{ActiveIterator::NONE};
-  uint8_t batch_message_type_{0};  // Current message type during batch encoding
-  // Total: 2 (flags) + 2 + 2 + 1 + 1 = 8 bytes, aligned to 4-byte boundary
+  // Total: 2 (flags) + 2 + 1 + 1 + 1 + 1 (batch_header_size_ below) = 8 bytes,
+  // aligned to 4-byte boundary
 
   // Actual header size used by encode_to_buffer for the current message.
   // Read by process_batch_multi_ to pass into MessageInfo.
@@ -813,7 +790,7 @@ class APIConnection final : public APIServerConnectionBase {
   // 2. It's an EventResponse (events are edge-triggered - every occurrence matters)
   // 3. OR: User has opted into immediate sending (should_try_send_immediately = true
   //    AND batch_delay = 0)
-  inline bool should_send_immediately_(uint8_t message_type) const {
+  inline bool should_send_immediately_(uint16_t message_type) const {
     return (
 #ifdef USE_UPDATE
         message_type == UpdateStateResponse::MESSAGE_TYPE ||
@@ -827,11 +804,11 @@ class APIConnection final : public APIServerConnectionBase {
   // Helper method to send a message either immediately or via batching
   // Tries immediate send if should_send_immediately_() returns true and buffer has space
   // Falls back to batching if immediate send fails or isn't applicable
-  bool send_message_smart_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
+  bool send_message_smart_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size,
                            uint8_t aux_data_index = DeferredBatch::AUX_DATA_UNUSED);
 
   // Helper function to schedule a deferred message with known message type
-  bool schedule_message_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
+  bool schedule_message_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size,
                          uint8_t aux_data_index = DeferredBatch::AUX_DATA_UNUSED) {
     this->deferred_batch_.add_item(entity, message_type, estimated_size, aux_data_index);
     return this->schedule_batch_();
@@ -839,7 +816,7 @@ class APIConnection final : public APIServerConnectionBase {
 
   // Helper function to schedule a high priority message at the front of the batch
   // Out-of-line: callers (on_shutdown, check_keepalive_) are cold paths
-  bool schedule_message_front_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size);
+  bool schedule_message_front_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size);
 
   // Helper function to log client messages with name and peername
   void log_client_(int level, const LogString *message);
@@ -850,6 +827,9 @@ class APIConnection final : public APIServerConnectionBase {
     this->on_fatal_error();
     this->log_warning_(message, err);
   }
+  // Shared cold path for buffer allocation failures — noinline keeps the
+  // OOM handling out of the hot send paths
+  void __attribute__((noinline)) fatal_out_of_memory_();
 };
 
 }  // namespace esphome::api

esphome/components/api/api_connection_buffer.h

@@ -3,8 +3,8 @@
 #include "esphome/core/defines.h"
 #ifdef USE_API
 
-// Inline APIConnection methods that need APIServer complete. Include this
-// instead of api_connection.h when calling encode_to_buffer or get_batch_delay_ms_.
+// Inline APIConnection members that need APIServer complete. Include this
+// instead of api_connection.h when calling them.
 
 #include "api_connection.h"
 #include "api_server.h"
@@ -41,14 +41,40 @@ inline uint16_t ESPHOME_ALWAYS_INLINE APIConnection::encode_to_buffer(uint32_t c
     return 0;
 
   auto &shared_buf = conn->parent_->get_shared_buffer_ref();
-  shared_buf.resize(shared_buf.size() + to_add);
+  if (!shared_buf.resize(shared_buf.size() + to_add)) [[unlikely]] {
+    conn->fatal_out_of_memory_();
+    return 0;
+  }
   ProtoWriteBuffer buffer{&shared_buf, shared_buf.size() - calculated_size};
-  encode_fn(msg, buffer PROTO_ENCODE_DEBUG_INIT(&shared_buf));
+  uint8_t *end = encode_fn(msg, buffer PROTO_ENCODE_DEBUG_INIT(&shared_buf));
+#ifdef ESPHOME_DEBUG_API
+  // A body that writes fewer bytes than calculate_size() promised would ship stale buffer bytes
+  proto_check_encode_end(end, shared_buf.data() + shared_buf.size());
+#else
+  (void) end;
+#endif
 
   return total_calculated_size;
 }
 
 inline uint32_t APIConnection::get_batch_delay_ms_() const { return this->parent_->get_batch_delay(); }
 
+inline bool APIConnection::prepare_first_message_buffer(size_t header_padding, size_t total_size) {
+  auto &shared_buf = this->parent_->get_shared_buffer_ref();
+  shared_buf.clear();
+  // Reserve space for header padding + message + footer
+  // - Header padding: space for protocol headers (7 bytes for Noise, 6 for Plaintext)
+  // - Footer: space for MAC (16 bytes for Noise, 0 for Plaintext)
+  // Reserve full size but only set initial size to header padding
+  // so message encoding starts at the correct position
+  return shared_buf.reserve_and_resize(total_size, header_padding);
+}
+
+inline bool APIConnection::prepare_first_message_buffer(size_t payload_size) {
+  const uint8_t header_padding = this->helper_->frame_header_padding();
+  const uint8_t footer_size = this->helper_->frame_footer_size();
+  return this->prepare_first_message_buffer(header_padding, payload_size + header_padding + footer_size);
+}
+
 }  // namespace esphome::api
 #endif

esphome/components/api/api_frame_helper.cpp

@@ -171,8 +171,8 @@ APIError APIFrameHelper::write_raw_iov_(const struct iovec *iov, int iovcnt, uin
     return APIError::OK;
 
   // Queue unsent data into overflow buffer
-  if (!this->overflow_buf_.enqueue_iov(iov, iovcnt, total_write_len, static_cast<uint16_t>(sent))) {
-    HELPER_LOG("Overflow buffer full, dropping connection");
+  if (!this->overflow_buf_.enqueue_iov(iov, iovcnt, total_write_len, sent)) {
+    HELPER_LOG("Overflow buffer full or out of memory, dropping connection");
     this->state_ = State::FAILED;
     return APIError::SOCKET_WRITE_FAILED;
   }

esphome/components/api/api_frame_helper.h

@@ -49,16 +49,16 @@ struct ReadPacketBuffer {
 };
 
 // Packed message info structure to minimize memory usage
-// Note: message_type is uint8_t — all current protobuf message types fit in 8 bits.
-// The noise wire format encodes types as 16-bit, but the high byte is always 0.
-// If message types ever exceed 255, this and encrypt_noise_message_ must be updated.
+// message_type matches the wire formats: noise carries a fixed 16-bit type
+// field, plaintext a type varint. The proto codegen caps message IDs at 16383
+// so the plaintext type varint fits the 2 bytes budgeted in HEADER_PADDING.
 struct MessageInfo {
   uint16_t offset;        // Offset in buffer where message starts
   uint16_t payload_size;  // Size of the message payload
-  uint8_t message_type;   // Message type (0-255)
+  uint16_t message_type;  // Message type (0-16383)
   uint8_t header_size;    // Actual header size used (avoids recomputation in write path)
 
-  MessageInfo(uint8_t type, uint16_t off, uint16_t size, uint8_t hdr)
+  MessageInfo(uint16_t type, uint16_t off, uint16_t size, uint8_t hdr)
       : offset(off), payload_size(size), message_type(type), header_size(hdr) {}
 };
 
@@ -173,7 +173,7 @@ class APIFrameHelper {
   }
   // Write a single protobuf message - the hot path (87-100% of all writes).
   // Caller must ensure state is DATA before calling.
-  virtual APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) = 0;
+  virtual APIError write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) = 0;
   // Write multiple protobuf messages in a single batched operation.
   // Caller must ensure state is DATA and messages is not empty.
   // messages contains (message_type, offset, length) for each message in the buffer.
@@ -187,15 +187,15 @@ class APIFrameHelper {
   // Distinguishes protocols via frame_footer_size_ (noise always has a non-zero MAC
   // footer, plaintext has footer=0). If a protocol with a plaintext footer is ever
   // added, this should become a virtual method.
-  uint8_t frame_header_size(uint16_t payload_size, uint8_t message_type) const {
+  uint8_t frame_header_size(uint16_t payload_size, uint16_t message_type) const {
 #if defined(USE_API_NOISE) && defined(USE_API_PLAINTEXT)
     return this->frame_footer_size_
                ? this->frame_header_padding_
-               : static_cast<uint8_t>(1 + ProtoSize::varint16(payload_size) + ProtoSize::varint8(message_type));
+               : static_cast<uint8_t>(1 + ProtoSize::varint16(payload_size) + ProtoSize::varint16(message_type));
 #elif defined(USE_API_NOISE)
     return this->frame_header_padding_;
 #else  // USE_API_PLAINTEXT only
-    return static_cast<uint8_t>(1 + ProtoSize::varint16(payload_size) + ProtoSize::varint8(message_type));
+    return static_cast<uint8_t>(1 + ProtoSize::varint16(payload_size) + ProtoSize::varint16(message_type));
 #endif
   }
   // Get the frame footer size required by this protocol
@@ -219,7 +219,10 @@ class APIFrameHelper {
     if (this->rx_buf_len_ == 0) {
       this->rx_buf_.release();
     }
+    this->release_overflow_buffer();
   }
+  // Free the send backlog storage once it has drained
+  void release_overflow_buffer() { this->overflow_buf_.release(); }
 
  protected:
   // Drain backlogged overflow data to the socket and handle errors.

esphome/components/api/api_frame_helper_noise.cpp

@@ -5,16 +5,13 @@
 #include "esphome/components/noise/noise.h"
 #include "esphome/core/application.h"
 #include "esphome/core/entity_base.h"
+#include "esphome/core/hal.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 #include "proto.h"
 #include <cstring>
 #include <cinttypes>
 
-#ifdef USE_ESP8266
-#include <pgmspace.h>
-#endif
-
 namespace esphome::api {
 
 using noise::noise_err_to_logstr;
@@ -26,11 +23,7 @@ static_assert(MAX_HANDSHAKE_SIZE == noise::MAX_HANDSHAKE_SIZE,
               "api and noise component handshake size limits must match");
 
 static const char *const TAG = "api.noise";
-#ifdef USE_ESP8266
 static constexpr char PROLOGUE_INIT[] PROGMEM = "NoiseAPIInit";
-#else
-static const char *const PROLOGUE_INIT = "NoiseAPIInit";
-#endif
 static constexpr size_t PROLOGUE_INIT_LEN = 12;  // strlen("NoiseAPIInit")
 
 // Maximum bytes to log in hex format (168 * 3 = 504, under TX buffer size of 512)
@@ -67,13 +60,12 @@ APIError APINoiseFrameHelper::init() {
   }
 
   // init prologue
-  size_t old_size = prologue_.size();
-  prologue_.resize(old_size + PROLOGUE_INIT_LEN);
-#ifdef USE_ESP8266
-  memcpy_P(prologue_.data() + old_size, PROLOGUE_INIT, PROLOGUE_INIT_LEN);
-#else
-  std::memcpy(prologue_.data() + old_size, PROLOGUE_INIT, PROLOGUE_INIT_LEN);
-#endif
+  uint8_t *dst = prologue_.append(PROLOGUE_INIT_LEN);
+  if (dst == nullptr) [[unlikely]] {
+    state_ = State::FAILED;
+    return APIError::OUT_OF_MEMORY;
+  }
+  progmem_memcpy(dst, PROLOGUE_INIT, PROLOGUE_INIT_LEN);
 
   state_ = State::CLIENT_HELLO;
   return APIError::OK;
@@ -202,7 +194,10 @@ APIError APINoiseFrameHelper::try_read_frame_() {
   // During handshake, rx_buf_.size() is used in prologue construction, so
   // the buffer must be exactly msg_size to avoid prologue mismatch.)
   uint16_t alloc_size = msg_size + (is_data ? RX_BUF_NULL_TERMINATOR : 0);
-  this->rx_buf_.resize(alloc_size);
+  if (!this->rx_buf_.resize(alloc_size)) [[unlikely]] {
+    state_ = State::FAILED;
+    return APIError::OUT_OF_MEMORY;
+  }
 
   if (rx_buf_len_ < msg_size) {
     // more data to read
@@ -266,14 +261,17 @@ APIError APINoiseFrameHelper::state_action_client_hello_() {
     return handle_handshake_frame_error_(aerr);
   }
   // ignore contents, may be used in future for flags
-  // Resize for: existing prologue + 2 size bytes + frame data
-  size_t old_size = this->prologue_.size();
+  // Append 2 size bytes + frame data to the prologue
   size_t rx_size = this->rx_buf_.size();
-  this->prologue_.resize(old_size + 2 + rx_size);
-  this->prologue_[old_size] = (uint8_t) (rx_size >> 8);
-  this->prologue_[old_size + 1] = (uint8_t) rx_size;
+  uint8_t *dst = this->prologue_.append(2 + rx_size);
+  if (dst == nullptr) [[unlikely]] {
+    state_ = State::FAILED;
+    return APIError::OUT_OF_MEMORY;
+  }
+  dst[0] = (uint8_t) (rx_size >> 8);
+  dst[1] = (uint8_t) rx_size;
   if (rx_size > 0) {
-    std::memcpy(this->prologue_.data() + old_size + 2, this->rx_buf_.data(), rx_size);
+    std::memcpy(dst + 2, this->rx_buf_.data(), rx_size);
   }
 
   state_ = State::SERVER_HELLO;
@@ -442,7 +440,7 @@ APIError APINoiseFrameHelper::read_packet(ReadPacketBuffer *buffer) {
 }
 // Encrypt a single noise message in place and return the encrypted frame length.
 // Returns APIError::OK on success.
-APIError APINoiseFrameHelper::encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint8_t message_type,
+APIError APINoiseFrameHelper::encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint16_t message_type,
                                                      uint16_t &encrypted_len_out) {
   // The noise frame header is written after encryption, when the size is known
 
@@ -472,18 +470,20 @@ APIError APINoiseFrameHelper::encrypt_noise_message_(uint8_t *buf_start, uint16_
   return APIError::OK;
 }
 
-APIError APINoiseFrameHelper::write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) {
+APIError APINoiseFrameHelper::write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) {
 #ifdef ESPHOME_DEBUG_API
   assert(this->state_ == State::DATA);
 #endif
 
+  APIBuffer *buf = buffer.get_buffer();
   // Resize buffer to include footer space for Noise MAC
-  if (this->frame_footer_size_)
-    buffer.get_buffer()->resize(buffer.get_buffer()->size() + this->frame_footer_size_);
+  if (this->frame_footer_size_ && !buf->resize(buf->size() + this->frame_footer_size_)) [[unlikely]] {
+    state_ = State::FAILED;
+    return APIError::OUT_OF_MEMORY;
+  }
 
-  uint16_t payload_size =
-      static_cast<uint16_t>(buffer.get_buffer()->size() - HEADER_PADDING - this->frame_footer_size_);
-  uint8_t *buf_start = buffer.get_buffer()->data();
+  uint16_t payload_size = static_cast<uint16_t>(buf->size() - HEADER_PADDING - this->frame_footer_size_);
+  uint8_t *buf_start = buf->data();
   uint16_t encrypted_len;
   APIError aerr = this->encrypt_noise_message_(buf_start, payload_size, type, encrypted_len);
   if (aerr != APIError::OK)
@@ -537,7 +537,7 @@ APIError APINoiseFrameHelper::write_frame_(const uint8_t *data, uint16_t len) {
  * @return 0 on success, -1 on error (check errno)
  */
 APIError APINoiseFrameHelper::init_handshake_() {
-  int err = this->handshake_.init(this->ctx_.get_psk(), prologue_.data(), prologue_.size());
+  int err = this->handshake_.init(this->ctx_, prologue_.data(), prologue_.size());
   APIError aerr = handle_noise_error_(err, LOG_STR("noise_handshake_init"), APIError::HANDSHAKESTATE_SETUP_FAILED);
   if (aerr != APIError::OK)
     return aerr;

esphome/components/api/api_frame_helper_noise.h

@@ -31,7 +31,7 @@ class APINoiseFrameHelper final : public APIFrameHelper {
 #endif
   APIError loop() override;
   APIError read_packet(ReadPacketBuffer *buffer) override;
-  APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) override;
+  APIError write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) override;
   APIError write_protobuf_messages(ProtoWriteBuffer buffer, std::span<const MessageInfo> messages) override;
 
  protected:
@@ -44,7 +44,7 @@ class APINoiseFrameHelper final : public APIFrameHelper {
   APIError state_action_handshake_write_();
   APIError try_read_frame_();
   APIError write_frame_(const uint8_t *data, uint16_t len);
-  APIError encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint8_t message_type,
+  APIError encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint16_t message_type,
                                   uint16_t &encrypted_len_out);
   APIError init_handshake_();
   APIError check_handshake_finished_();

esphome/components/api/api_frame_helper_plaintext.cpp

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

esphome/components/api/api_frame_helper_plaintext.h

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

esphome/components/api/api_overflow_buffer.cpp

@@ -4,83 +4,88 @@
 
 namespace esphome::api {
 
-APIOverflowBuffer::~APIOverflowBuffer() {
-  for (auto *entry : this->queue_) {
-    if (entry != nullptr)
-      Entry::destroy(entry);
-  }
-}
-
 ssize_t APIOverflowBuffer::try_drain(socket::Socket *socket) {
-  // socket->write() can re-enter this function: a log message emitted from an
-  // lwip callback during the write goes out over the API and lands back in the
-  // frame helper's write/drain path. If a nested drain ran here it would send
-  // and free the entry the outer drain is still holding, causing a double free.
-  // Report "no progress" instead; the outer drain keeps draining, and the
-  // nested send is enqueued behind the existing backlog.
+  // Nested call from inside socket->write(); see draining_
   if (this->draining_)
     return 0;
 
-  // RAII so the flag is cleared on every return path
   struct DrainGuard {
-    explicit DrainGuard(bool &flag) : flag_(flag) { flag_ = true; }
-    ~DrainGuard() { this->flag_ = false; }
-    bool &flag_;
-  } guard(this->draining_);
+    APIOverflowBuffer &owner;
+    ~DrainGuard() { this->owner.draining_ = false; }
+  } guard{*this};
+  this->draining_ = true;
 
   while (this->count_ > 0) {
-    Entry *front = this->queue_[this->head_];
+    uint8_t *msg = this->buf_.data() + this->head_;
+    size_t len = msg[0] | (msg[1] << 8);
 
-    ssize_t sent = socket->write(front->current_data(), front->remaining());
-
-    if (sent <= 0) {
-      // -1 = error (caller checks errno for EWOULDBLOCK vs hard error)
-      // 0 = nothing sent (treat as no progress)
+    ssize_t sent = socket->write(msg + LEN_PREFIX, len);
+    if (sent <= 0)
+      return sent;
+    if (static_cast<size_t>(sent) < len) {
+      // Step past the sent bytes and rewrite the prefix there; it lands on bytes already sent
+      this->head_ += sent;
+      len -= sent;
+      msg += sent;
+      msg[0] = len;
+      msg[1] = len >> 8;
       return sent;
     }
-
-    if (static_cast<uint16_t>(sent) < front->remaining()) {
-      // Partially sent, update offset and stop
-      front->offset += static_cast<uint16_t>(sent);
-      return sent;
-    }
-
-    // Entry fully sent — unlink it before freeing so a freed pointer is never
-    // reachable from the queue
-    this->queue_[this->head_] = nullptr;
-    this->head_ = (this->head_ + 1) % API_MAX_SEND_QUEUE;
+    this->head_ += LEN_PREFIX + len;
     this->count_--;
-    Entry::destroy(front);
   }
 
-  return 0;  // All drained
+  this->head_ = 0;
+  if (this->release_when_drained_) {
+    this->release_when_drained_ = false;
+    this->buf_.release();
+  } else {
+    this->buf_.clear();
+  }
+  return 0;
 }
 
-bool APIOverflowBuffer::enqueue_iov(const struct iovec *iov, int iovcnt, uint16_t total_len, uint16_t skip) {
+bool APIOverflowBuffer::enqueue_iov(const struct iovec *iov, int iovcnt, size_t total_len, size_t skip) {
   if (this->count_ >= API_MAX_SEND_QUEUE)
     return false;
 
-  uint16_t buffer_size = total_len - skip;
-  // NOLINTNEXTLINE(cppcoreguidelines-owning-memory)
-  auto *entry = new Entry{new uint8_t[buffer_size], buffer_size, 0};
-  this->queue_[this->tail_] = entry;
+  const size_t new_len = total_len - skip;
+  const size_t new_bytes = LEN_PREFIX + new_len;
+  const size_t live = this->buf_.size() - this->head_;
+  // A lone message is only bound by the buffer; refusing it would just drop the connection
+  if (live + new_bytes > (this->count_ > 0 ? MAX_BYTES : MAX_LONE_BYTES))
+    return false;
 
-  uint16_t to_skip = skip;
-  uint16_t write_pos = 0;
+  if (this->buf_.size() + new_bytes > this->buf_.capacity()) {
+    // Storage would move under an outer drain's write()
+    if (this->draining_)
+      return false;
+    if (this->head_ > 0) {
+      // Reclaim the sent prefix before growing
+      this->buf_.drop_front(this->head_);
+      this->head_ = 0;
+    }
+    if (!this->buf_.reserve(reserve_for(live + new_bytes)))
+      return false;
+  }
 
-  for (int i = 0; i < iovcnt; i++) {
-    if (to_skip >= iov[i].iov_len) {
-      to_skip -= static_cast<uint16_t>(iov[i].iov_len);
+  uint8_t *dst = this->buf_.append(new_bytes);
+  if (dst == nullptr)
+    return false;
+  dst[0] = new_len;
+  dst[1] = new_len >> 8;
+  dst += LEN_PREFIX;
+  for (const struct iovec *end = iov + iovcnt; iov != end; iov++) {
+    if (skip >= iov->iov_len) {
+      skip -= iov->iov_len;
     } else {
-      const uint8_t *src = reinterpret_cast<uint8_t *>(iov[i].iov_base) + to_skip;
-      uint16_t len = static_cast<uint16_t>(iov[i].iov_len) - to_skip;
-      std::memcpy(entry->data + write_pos, src, len);
-      write_pos += len;
-      to_skip = 0;
+      const size_t len = iov->iov_len - skip;
+      std::memcpy(dst, static_cast<const uint8_t *>(iov->iov_base) + skip, len);
+      dst += len;
+      skip = 0;
     }
   }
 
-  this->tail_ = (this->tail_ + 1) % API_MAX_SEND_QUEUE;
   this->count_++;
   return true;
 }

esphome/components/api/api_overflow_buffer.h

@@ -1,5 +1,6 @@
 #pragma once
-#include <array>
+#include <algorithm>
+#include <cstddef>
 #include <cstdint>
 #include <sys/types.h>
 
@@ -8,71 +9,57 @@
 
 #include "esphome/components/socket/headers.h"
 #include "esphome/components/socket/socket.h"
-#include "esphome/core/helpers.h"
+#include "api_buffer.h"
 
 namespace esphome::api {
 
-/// Circular queue of heap-allocated byte buffers used as a TCP send backlog.
-///
-/// Under normal operation this buffer is **never used** — data goes straight
-/// from the frame helper to the socket.  It only fills when the LWIP TCP
-/// send buffer is full (slow client, congested network, heavy logging).
-/// The queue drains automatically on subsequent write/loop calls once the
-/// socket becomes writable again.
-///
-/// Capacity is compile-time-fixed via API_MAX_SEND_QUEUE (set from Python
-/// config).  If the queue fills completely the connection is marked failed.
+/// TCP send backlog, only used when the socket send buffer is full.
+/// One contiguous buffer per connection, allocated on the first stall and
+/// kept at its high-water mark so a lossy link does not churn the heap.
+/// Messages are stored as a 2 byte length prefix plus payload.
+/// API_MAX_SEND_QUEUE bounds queued messages and, at 2 KB per slot, queued
+/// bytes; exceeding either fails the connection.
 class APIOverflowBuffer {
  public:
-  /// A single heap-allocated send-backlog entry.
-  /// Lifetime is manually managed — see destroy().
-  struct Entry {
-    uint8_t *data;
-    uint16_t size;    // Total size of the buffer
-    uint16_t offset;  // Current send offset within the buffer
-
-    uint16_t remaining() const { return this->size - this->offset; }
-    const uint8_t *current_data() const { return this->data + this->offset; }
-
-    /// Free this entry and its data buffer.
-    static ESPHOME_ALWAYS_INLINE void destroy(Entry *entry) {
-      delete[] entry->data;
-      delete entry;  // NOLINT(cppcoreguidelines-owning-memory)
-    }
-  };
-
-  ~APIOverflowBuffer();
-
   /// True when no backlogged data is waiting.
   bool empty() const { return this->count_ == 0; }
 
-  /// True when the queue has no room for another entry.
-  bool full() const { return this->count_ >= API_MAX_SEND_QUEUE; }
-
-  /// Number of entries currently queued.
-  uint8_t count() const { return this->count_; }
-
-  /// Try to drain queued data to the socket.
-  /// Returns bytes-written > 0 on success/partial, 0 if all drained or no progress,
-  /// -1 on error (caller must check errno to distinguish EWOULDBLOCK from hard errors).
-  /// Callers only need to act on -1; 0 and positive values both mean "no error".
-  /// Frees entries as they are fully sent.
+  /// Drain queued messages to the socket.
+  /// Returns bytes written, 0 for a re-entrant call, -1 on error (check errno
+  /// for EWOULDBLOCK); callers only need to act on -1.
   ssize_t try_drain(socket::Socket *socket);
 
-  /// Enqueue unsent IOV data into the backlog.
-  /// Copies iov data starting at byte offset `skip` into a new entry.
-  /// Returns false if the queue is full (caller should fail the connection).
-  bool enqueue_iov(const struct iovec *iov, int iovcnt, uint16_t total_len, uint16_t skip);
+  /// Queue iov data from byte offset `skip` as one message.
+  /// Returns false when a limit is hit, allocation fails, or storage would move
+  /// during a drain; the caller should fail the connection.
+  bool enqueue_iov(const struct iovec *iov, int iovcnt, size_t total_len, size_t skip);
+
+  /// Free the retained storage, now if empty, otherwise once it has drained.
+  void release() {
+    if (this->count_ == 0) {
+      this->buf_.release();
+    } else {
+      this->release_when_drained_ = true;
+    }
+  }
 
  protected:
-  std::array<Entry *, API_MAX_SEND_QUEUE> queue_{};
-  uint8_t head_{0};
-  uint8_t tail_{0};
+  static constexpr size_t LEN_PREFIX = 2;
+  static constexpr size_t BYTES_PER_SLOT = 2048;
+  // Reserve in 256 byte steps so a creeping high-water mark settles quickly
+  static constexpr size_t GROW_QUANTUM = 256;
+  // Lone message ceiling, rounded down so reserve_for() never exceeds the buffer limit
+  static constexpr size_t MAX_LONE_BYTES = APIBuffer::MAX_SIZE & ~(GROW_QUANTUM - 1);
+  static constexpr size_t MAX_BYTES = std::min(API_MAX_SEND_QUEUE * BYTES_PER_SLOT, MAX_LONE_BYTES);
+  static constexpr size_t reserve_for(size_t want) { return (want + GROW_QUANTUM - 1) & ~(GROW_QUANTUM - 1); }
+
+  APIBuffer buf_;
+  uint16_t head_{0};  // offset of the front message's length prefix; bytes before it are sent
   uint8_t count_{0};
-  // Guards against re-entrant drains: socket->write() can re-enter the API
-  // send path (e.g. a log message emitted from an lwip callback), and a nested
-  // drain would free the entry the outer drain is still holding.
-  bool draining_{false};
+  // socket->write() can re-enter the send path (log from an lwip callback):
+  // a nested drain makes no progress and a nested enqueue never moves storage
+  bool draining_ : 1 {false};
+  bool release_when_drained_ : 1 {false};
 };
 
 }  // namespace esphome::api

esphome/components/api/api_pb2_dump.cpp

@@ -816,6 +816,18 @@ template<> const char *proto_enum_to_string<enums::ZWaveProxyRequestType>(enums:
       return ESPHOME_PSTR("UNKNOWN");
   }
 }
+template<> const char *proto_enum_to_string<enums::ZWaveProxyStatus>(enums::ZWaveProxyStatus value) {
+  switch (value) {
+    case enums::ZWAVE_PROXY_STATUS_OK:
+      return ESPHOME_PSTR("ZWAVE_PROXY_STATUS_OK");
+    case enums::ZWAVE_PROXY_STATUS_IN_USE:
+      return ESPHOME_PSTR("ZWAVE_PROXY_STATUS_IN_USE");
+    case enums::ZWAVE_PROXY_STATUS_NOT_SUPPORTED:
+      return ESPHOME_PSTR("ZWAVE_PROXY_STATUS_NOT_SUPPORTED");
+    default:
+      return ESPHOME_PSTR("UNKNOWN");
+  }
+}
 #endif
 #ifdef USE_SERIAL_PROXY
 template<> const char *proto_enum_to_string<enums::SerialProxyParity>(enums::SerialProxyParity value) {
@@ -838,6 +850,12 @@ template<> const char *proto_enum_to_string<enums::SerialProxyRequestType>(enums
       return ESPHOME_PSTR("SERIAL_PROXY_REQUEST_TYPE_UNSUBSCRIBE");
     case enums::SERIAL_PROXY_REQUEST_TYPE_FLUSH:
       return ESPHOME_PSTR("SERIAL_PROXY_REQUEST_TYPE_FLUSH");
+    case enums::SERIAL_PROXY_REQUEST_TYPE_CONFIGURE:
+      return ESPHOME_PSTR("SERIAL_PROXY_REQUEST_TYPE_CONFIGURE");
+    case enums::SERIAL_PROXY_REQUEST_TYPE_SET_MODEM_PINS:
+      return ESPHOME_PSTR("SERIAL_PROXY_REQUEST_TYPE_SET_MODEM_PINS");
+    case enums::SERIAL_PROXY_REQUEST_TYPE_SET_MODE:
+      return ESPHOME_PSTR("SERIAL_PROXY_REQUEST_TYPE_SET_MODE");
     default:
       return ESPHOME_PSTR("UNKNOWN");
   }
@@ -854,6 +872,20 @@ template<> const char *proto_enum_to_string<enums::SerialProxyStatus>(enums::Ser
       return ESPHOME_PSTR("SERIAL_PROXY_STATUS_TIMEOUT");
     case enums::SERIAL_PROXY_STATUS_NOT_SUPPORTED:
       return ESPHOME_PSTR("SERIAL_PROXY_STATUS_NOT_SUPPORTED");
+    case enums::SERIAL_PROXY_STATUS_PORT_IN_USE:
+      return ESPHOME_PSTR("SERIAL_PROXY_STATUS_PORT_IN_USE");
+    case enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT:
+      return ESPHOME_PSTR("SERIAL_PROXY_STATUS_INVALID_ARGUMENT");
+    default:
+      return ESPHOME_PSTR("UNKNOWN");
+  }
+}
+template<> const char *proto_enum_to_string<enums::SerialProxyMode>(enums::SerialProxyMode value) {
+  switch (value) {
+    case enums::SERIAL_PROXY_MODE_RAW:
+      return ESPHOME_PSTR("SERIAL_PROXY_MODE_RAW");
+    case enums::SERIAL_PROXY_MODE_PROTOCOL:
+      return ESPHOME_PSTR("SERIAL_PROXY_MODE_PROTOCOL");
     default:
       return ESPHOME_PSTR("UNKNOWN");
   }
@@ -914,6 +946,7 @@ const char *SerialProxyInfo::dump_to(DumpBuffer &out) const {
   MessageDumpHelper helper(out, ESPHOME_PSTR("SerialProxyInfo"));
   dump_field(out, ESPHOME_PSTR("name"), this->name);
   dump_field(out, ESPHOME_PSTR("port_type"), static_cast<enums::SerialProxyPortType>(this->port_type));
+  dump_field(out, ESPHOME_PSTR("configured_line_states"), this->configured_line_states);
   return out.c_str();
 }
 #endif
@@ -1309,6 +1342,7 @@ const char *SwitchStateResponse::dump_to(DumpBuffer &out) const {
 #ifdef USE_DEVICES
   dump_field(out, ESPHOME_PSTR("device_id"), this->device_id);
 #endif
+  dump_field(out, ESPHOME_PSTR("missing_state"), this->missing_state);
   return out.c_str();
 }
 const char *SwitchCommandRequest::dump_to(DumpBuffer &out) const {
@@ -1479,6 +1513,12 @@ const char *ListEntitiesServicesArgument::dump_to(DumpBuffer &out) const {
   MessageDumpHelper helper(out, ESPHOME_PSTR("ListEntitiesServicesArgument"));
   dump_field(out, ESPHOME_PSTR("name"), this->name);
   dump_field(out, ESPHOME_PSTR("type"), static_cast<enums::ServiceArgType>(this->type));
+#ifdef USE_API_USER_DEFINED_ACTION_METADATA
+  dump_field(out, ESPHOME_PSTR("description"), this->description);
+#endif
+#ifdef USE_API_USER_DEFINED_ACTION_METADATA
+  dump_field(out, ESPHOME_PSTR("example"), this->example);
+#endif
   return out.c_str();
 }
 const char *ListEntitiesServicesResponse::dump_to(DumpBuffer &out) const {
@@ -1491,6 +1531,9 @@ const char *ListEntitiesServicesResponse::dump_to(DumpBuffer &out) const {
     out.append("\n");
   }
   dump_field(out, ESPHOME_PSTR("supports_response"), static_cast<enums::SupportsResponseType>(this->supports_response));
+#ifdef USE_API_USER_DEFINED_ACTION_METADATA
+  dump_field(out, ESPHOME_PSTR("description"), this->description);
+#endif
   return out.c_str();
 }
 const char *ExecuteServiceArgument::dump_to(DumpBuffer &out) const {
@@ -1642,6 +1685,7 @@ const char *ClimateStateResponse::dump_to(DumpBuffer &out) const {
 #ifdef USE_DEVICES
   dump_field(out, ESPHOME_PSTR("device_id"), this->device_id);
 #endif
+  dump_field(out, ESPHOME_PSTR("missing_state"), this->missing_state);
   return out.c_str();
 }
 const char *ClimateCommandRequest::dump_to(DumpBuffer &out) const {
@@ -1709,6 +1753,7 @@ const char *WaterHeaterStateResponse::dump_to(DumpBuffer &out) const {
   dump_field(out, ESPHOME_PSTR("state"), this->state);
   dump_field(out, ESPHOME_PSTR("target_temperature_low"), this->target_temperature_low);
   dump_field(out, ESPHOME_PSTR("target_temperature_high"), this->target_temperature_high);
+  dump_field(out, ESPHOME_PSTR("missing_state"), this->missing_state);
   return out.c_str();
 }
 const char *WaterHeaterCommandRequest::dump_to(DumpBuffer &out) const {
@@ -1941,7 +1986,6 @@ const char *ListEntitiesMediaPlayerResponse::dump_to(DumpBuffer &out) const {
 #endif
   dump_field(out, ESPHOME_PSTR("disabled_by_default"), this->disabled_by_default);
   dump_field(out, ESPHOME_PSTR("entity_category"), static_cast<enums::EntityCategory>(this->entity_category));
-  dump_field(out, ESPHOME_PSTR("supports_pause"), this->supports_pause);
   for (const auto &it : this->supported_formats) {
     out.append(4, ' ').append_p(ESPHOME_PSTR("supported_formats")).append(": ");
     it.dump_to(out);
@@ -2644,6 +2688,12 @@ const char *ZWaveProxyRequest::dump_to(DumpBuffer &out) const {
   dump_bytes_field(out, ESPHOME_PSTR("data"), this->data, this->data_len);
   return out.c_str();
 }
+const char *ZWaveProxyRequestResponse::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, ESPHOME_PSTR("ZWaveProxyRequestResponse"));
+  dump_field(out, ESPHOME_PSTR("type"), static_cast<enums::ZWaveProxyRequestType>(this->type));
+  dump_field(out, ESPHOME_PSTR("status"), static_cast<enums::ZWaveProxyStatus>(this->status));
+  return out.c_str();
+}
 #endif
 #ifdef USE_INFRARED
 const char *ListEntitiesInfraredResponse::dump_to(DumpBuffer &out) const {
@@ -2753,6 +2803,7 @@ const char *SerialProxyGetModemPinsResponse::dump_to(DumpBuffer &out) const {
   MessageDumpHelper helper(out, ESPHOME_PSTR("SerialProxyGetModemPinsResponse"));
   dump_field(out, ESPHOME_PSTR("instance"), this->instance);
   dump_field(out, ESPHOME_PSTR("line_states"), this->line_states);
+  dump_field(out, ESPHOME_PSTR("status"), static_cast<enums::SerialProxyStatus>(this->status));
   return out.c_str();
 }
 const char *SerialProxyRequest::dump_to(DumpBuffer &out) const {
@@ -2769,6 +2820,12 @@ const char *SerialProxyRequestResponse::dump_to(DumpBuffer &out) const {
   dump_field(out, ESPHOME_PSTR("error_message"), this->error_message);
   return out.c_str();
 }
+const char *SerialProxySetModeRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, ESPHOME_PSTR("SerialProxySetModeRequest"));
+  dump_field(out, ESPHOME_PSTR("instance"), this->instance);
+  dump_field(out, ESPHOME_PSTR("mode"), static_cast<enums::SerialProxyMode>(this->mode));
+  return out.c_str();
+}
 #endif
 #ifdef USE_BLUETOOTH_PROXY_CONNECTIONS
 const char *BluetoothSetConnectionParamsRequest::dump_to(DumpBuffer &out) const {

esphome/components/api/api_pb2_service.cpp

@@ -712,6 +712,17 @@ void APIConnection::read_message_(uint32_t msg_size, uint32_t msg_type, const ui
       this->on_device_capabilities_request();
       break;
     }
+#ifdef USE_SERIAL_PROXY
+    case SerialProxySetModeRequest::MESSAGE_TYPE: {
+      SerialProxySetModeRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_serial_proxy_set_mode_request"), msg);
+#endif
+      this->on_serial_proxy_set_mode_request(msg);
+      break;
+    }
+#endif
     default:
       break;
   }

esphome/components/api/api_pb2_service.h

@@ -235,6 +235,9 @@ class APIServerConnectionBase {
   void on_serial_proxy_request(const SerialProxyRequest &value){};
 #endif
 
+#ifdef USE_SERIAL_PROXY
+  void on_serial_proxy_set_mode_request(const SerialProxySetModeRequest &value){};
+#endif
 #ifdef USE_BLUETOOTH_PROXY_CONNECTIONS
   void on_bluetooth_set_connection_params_request(const BluetoothSetConnectionParamsRequest &value){};
 #endif

esphome/components/api/api_server.cpp

@@ -5,7 +5,6 @@
 #include "api_connection.h"
 #include "esphome/components/network/util.h"
 #include "esphome/core/application.h"
-#include "esphome/core/controller_registry.h"
 #include "esphome/core/defines.h"
 #include "esphome/core/hal.h"
 #include "esphome/core/log.h"
@@ -29,6 +28,29 @@ static const char *const TAG = "api";
 // APIServer
 APIServer *global_api_server = nullptr;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 
+#ifdef USE_API_NOISE
+static constexpr uint32_t NOISE_PSK_PREF_HASH = 88491486UL;
+#endif
+
+#if defined(USE_API_NOISE) && defined(USE_OTA_ENCRYPTION_PROVISIONED)
+bool load_saved_noise_psk(noise::psk_t &out) {
+  SavedNoisePsk saved;
+#ifdef USE_PREFERENCE_KEY_LOOKUP
+  const bool loaded =
+      global_preferences->load_from_key(NOISE_PSK_PREF_HASH, reinterpret_cast<uint8_t *>(&saved), sizeof(saved));
+#else
+  // Slot backends need the reservation walk; it only lands on the record when the reservations before
+  // it match a normal boot, otherwise the type checked checksum fails the load
+  const bool loaded = global_preferences->make_preference<SavedNoisePsk>(NOISE_PSK_PREF_HASH, true).load(&saved);
+#endif
+  // The all-zeros record means no key
+  if (!loaded || noise::NoiseContext::is_all_zeros(saved.psk))
+    return false;
+  out = saved.psk;
+  return true;
+}
+#endif
+
 APIServer::APIServer() { global_api_server = this; }
 
 void APIServer::socket_failed_(const LogString *msg) {
@@ -38,16 +60,13 @@ void APIServer::socket_failed_(const LogString *msg) {
 }
 
 void APIServer::setup() {
-  ControllerRegistry::register_controller(this);
-
 #ifdef USE_API_NOISE
-  uint32_t hash = 88491486UL;
-
-  this->noise_pref_ = global_preferences->make_preference<SavedNoisePsk>(hash, true);
-
+  // Always reserve the slot: flash preferences are positional on esp8266, so
+  // a yaml key build must keep the layout of a runtime key build
+  this->noise_pref_ = global_preferences->make_preference<SavedNoisePsk>(NOISE_PSK_PREF_HASH, true);
 #ifndef USE_API_NOISE_PSK_FROM_YAML
-  // Only load saved PSK if not set from YAML
-  if (this->load_and_apply_noise_psk_()) {
+  // A cleared record loads fine but holds no key
+  if (this->load_and_apply_noise_psk_() && this->noise_ctx_.has_psk()) {
     ESP_LOGD(TAG, "Loaded saved Noise PSK");
   }
 #endif
@@ -433,8 +452,11 @@ void APIServer::send_homeassistant_action(const HomeassistantActionRequest &call
     // Home Assistant subscribes to actions shortly *after* authenticating, so actions
     // fired right at connection time (on_client_connected, on_time_sync, ...) can
     // arrive before the subscription and are lost - warn instead of failing silently.
-    ESP_LOGW(TAG, "Home Assistant %s '%s' dropped; %s", call.is_event ? "event" : "action", call.service.c_str(),
-             this->is_connected() ? "client has not subscribed to actions (yet)" : "no client connected");
+    ESP_LOGW(TAG, "Home Assistant %s '%.*s' dropped; %s",
+             call.is_event ? LOG_STR_LITERAL("event") : LOG_STR_LITERAL("action"),
+             static_cast<int>(call.service.size()), call.service.empty() ? "" : call.service.c_str(),
+             this->is_connected() ? LOG_STR_LITERAL("client has not subscribed to actions (yet)")
+                                  : LOG_STR_LITERAL("no client connected"));
   }
 }
 #ifdef USE_API_HOMEASSISTANT_ACTION_RESPONSES
@@ -548,6 +570,7 @@ const std::vector<APIServer::HomeAssistantStateSubscription> &APIServer::get_sta
 #endif
 
 #ifdef USE_API_NOISE
+#ifndef USE_API_NOISE_PSK_FROM_YAML
 bool APIServer::update_noise_psk_(const SavedNoisePsk &new_psk, const LogString *save_log_msg,
                                   const LogString *fail_log_msg, bool make_active) {
   if (!this->noise_pref_.save(&new_psk)) {
@@ -581,22 +604,19 @@ bool APIServer::update_noise_psk_(const SavedNoisePsk &new_psk, const LogString
 }
 
 bool APIServer::load_and_apply_noise_psk_() {
-  SavedNoisePsk saved{};
-  if (!this->noise_pref_.load(&saved))
+  // Load into a temp so a failed read cannot disturb the key in use
+  SavedNoisePsk loaded{};
+  if (!this->noise_pref_.load(&loaded))
     return false;
-  this->set_noise_psk(saved.psk);
+  this->saved_psk_ = loaded;
+  // An unprovisioned device stores the reserved all-zeros key, which is no key
+  const bool has_key = !noise::NoiseContext::is_all_zeros(this->saved_psk_.psk);
+  this->noise_ctx_.set_psk(has_key ? this->saved_psk_.psk.data() : nullptr);
   return true;
 }
 
 bool APIServer::save_noise_psk(noise::psk_t psk, bool make_active) {
-#ifdef USE_API_NOISE_PSK_FROM_YAML
-  // When PSK is set from YAML, this function should never be called
-  // but if it is, reject the change
-  ESP_LOGW(TAG, "Key set in YAML");
-  return false;
-#else
-  auto &old_psk = this->noise_ctx_.get_psk();
-  if (std::equal(old_psk.begin(), old_psk.end(), psk.begin())) {
+  if (this->saved_psk_.psk == psk) {
     ESP_LOGW(TAG, "New PSK matches old");
     return true;
   }
@@ -612,15 +632,8 @@ bool APIServer::save_noise_psk(noise::psk_t psk, bool make_active) {
   }
 #endif
   return result;
-#endif
 }
 bool APIServer::clear_noise_psk(bool make_active) {
-#ifdef USE_API_NOISE_PSK_FROM_YAML
-  // When PSK is set from YAML, this function should never be called
-  // but if it is, reject the change
-  ESP_LOGW(TAG, "Key set in YAML");
-  return false;
-#else
   SavedNoisePsk empty_psk{};
   bool result = this->update_noise_psk_(empty_psk, LOG_STR("Noise PSK cleared"), LOG_STR("Failed to clear Noise PSK"),
                                         make_active);
@@ -632,8 +645,8 @@ bool APIServer::clear_noise_psk(bool make_active) {
   }
 #endif
   return result;
-#endif
 }
+#endif  // USE_API_NOISE_PSK_FROM_YAML
 #endif
 
 #ifdef USE_HOMEASSISTANT_TIME

esphome/components/api/api_server.h

@@ -14,7 +14,7 @@
 #include "esphome/components/socket/socket.h"
 #include "esphome/core/automation.h"
 #include "esphome/core/component.h"
-#include "esphome/core/controller.h"
+#include "esphome/core/entity_includes.h"
 #include "esphome/core/log.h"
 #include "esphome/core/string_ref.h"
 #ifdef USE_PROVISIONING
@@ -43,9 +43,13 @@ struct SavedNoisePsk {
   noise::psk_t psk;
 } PACKED;  // NOLINT
 #endif
+#if defined(USE_API_NOISE) && defined(USE_OTA_ENCRYPTION_PROVISIONED)
+/// One-shot read of the provisioned key for a boot without an api server (safe mode); false when
+/// there is no key
+bool load_saved_noise_psk(noise::psk_t &out);
+#endif
 
-class APIServer final : public Component,
-                        public Controller
+class APIServer final : public Component
 #ifdef USE_CAMERA
     ,
                         public camera::CameraListener
@@ -76,66 +80,71 @@ class APIServer final : public Component,
   APIBuffer &get_shared_buffer_ref() { return shared_write_buffer_; }
 
 #ifdef USE_API_NOISE
+#ifndef USE_API_NOISE_PSK_FROM_YAML
+  // Runtime key changes exist for the provisioning path only (not lambdas);
+  // with a yaml key they compile out
   bool save_noise_psk(noise::psk_t psk, bool make_active = true);
   bool clear_noise_psk(bool make_active = true);
-  void set_noise_psk(noise::psk_t psk) { this->noise_ctx_.set_psk(psk); }
+#endif
+  /// psk points at 32 bytes that live in flash for the life of the program
+  void set_noise_psk(const uint8_t *psk) { this->noise_ctx_.set_psk(psk); }
   noise::NoiseContext &get_noise_ctx() { return this->noise_ctx_; }
 #endif  // USE_API_NOISE
 
   void handle_disconnect(APIConnection *conn);
 #ifdef USE_BINARY_SENSOR
-  void on_binary_sensor_update(binary_sensor::BinarySensor *obj) override;
+  void on_binary_sensor_update(binary_sensor::BinarySensor *obj);
 #endif
 #ifdef USE_COVER
-  void on_cover_update(cover::Cover *obj) override;
+  void on_cover_update(cover::Cover *obj);
 #endif
 #ifdef USE_FAN
-  void on_fan_update(fan::Fan *obj) override;
+  void on_fan_update(fan::Fan *obj);
 #endif
 #ifdef USE_LIGHT
-  void on_light_update(light::LightState *obj) override;
+  void on_light_update(light::LightState *obj);
 #endif
 #ifdef USE_SENSOR
-  void on_sensor_update(sensor::Sensor *obj) override;
+  void on_sensor_update(sensor::Sensor *obj);
 #endif
 #ifdef USE_SWITCH
-  void on_switch_update(switch_::Switch *obj) override;
+  void on_switch_update(switch_::Switch *obj);
 #endif
 #ifdef USE_TEXT_SENSOR
-  void on_text_sensor_update(text_sensor::TextSensor *obj) override;
+  void on_text_sensor_update(text_sensor::TextSensor *obj);
 #endif
 #ifdef USE_CLIMATE
-  void on_climate_update(climate::Climate *obj) override;
+  void on_climate_update(climate::Climate *obj);
 #endif
 #ifdef USE_NUMBER
-  void on_number_update(number::Number *obj) override;
+  void on_number_update(number::Number *obj);
 #endif
 #ifdef USE_DATETIME_DATE
-  void on_date_update(datetime::DateEntity *obj) override;
+  void on_date_update(datetime::DateEntity *obj);
 #endif
 #ifdef USE_DATETIME_TIME
-  void on_time_update(datetime::TimeEntity *obj) override;
+  void on_time_update(datetime::TimeEntity *obj);
 #endif
 #ifdef USE_DATETIME_DATETIME
-  void on_datetime_update(datetime::DateTimeEntity *obj) override;
+  void on_datetime_update(datetime::DateTimeEntity *obj);
 #endif
 #ifdef USE_TEXT
-  void on_text_update(text::Text *obj) override;
+  void on_text_update(text::Text *obj);
 #endif
 #ifdef USE_SELECT
-  void on_select_update(select::Select *obj) override;
+  void on_select_update(select::Select *obj);
 #endif
 #ifdef USE_LOCK
-  void on_lock_update(lock::Lock *obj) override;
+  void on_lock_update(lock::Lock *obj);
 #endif
 #ifdef USE_VALVE
-  void on_valve_update(valve::Valve *obj) override;
+  void on_valve_update(valve::Valve *obj);
 #endif
 #ifdef USE_MEDIA_PLAYER
-  void on_media_player_update(media_player::MediaPlayer *obj) override;
+  void on_media_player_update(media_player::MediaPlayer *obj);
 #endif
 #ifdef USE_WATER_HEATER
-  void on_water_heater_update(water_heater::WaterHeater *obj) override;
+  void on_water_heater_update(water_heater::WaterHeater *obj);
 #endif
 #ifdef USE_API_HOMEASSISTANT_SERVICES
   void send_homeassistant_action(const HomeassistantActionRequest &call);
@@ -178,13 +187,13 @@ class APIServer final : public Component,
 #endif
 
 #ifdef USE_ALARM_CONTROL_PANEL
-  void on_alarm_control_panel_update(alarm_control_panel::AlarmControlPanel *obj) override;
+  void on_alarm_control_panel_update(alarm_control_panel::AlarmControlPanel *obj);
 #endif
 #ifdef USE_EVENT
-  void on_event(event::Event *obj) override;
+  void on_event(event::Event *obj);
 #endif
 #ifdef USE_UPDATE
-  void on_update(update::UpdateEntity *obj) override;
+  void on_update(update::UpdateEntity *obj);
 #endif
 #ifdef USE_ZWAVE_PROXY
   void on_zwave_proxy_request(const ZWaveProxyRequest &msg);
@@ -275,10 +284,12 @@ class APIServer final : public Component,
 #endif
 
 #ifdef USE_API_NOISE
+#ifndef USE_API_NOISE_PSK_FROM_YAML
   bool update_noise_psk_(const SavedNoisePsk &new_psk, const LogString *save_log_msg, const LogString *fail_log_msg,
                          bool make_active);
   // Load saved PSK from preferences and apply it. Returns true on success.
   bool load_and_apply_noise_psk_();
+#endif  // USE_API_NOISE_PSK_FROM_YAML
 #endif  // USE_API_NOISE
 #ifdef USE_API_HOMEASSISTANT_STATES
   // Helper methods to reduce code duplication
@@ -307,7 +318,7 @@ class APIServer final : public Component,
 #endif
 
   // 4-byte aligned types
-  uint32_t reboot_timeout_{300000};
+  uint32_t reboot_timeout_{900000};  // Keep in sync with DEFAULT_REBOOT_TIMEOUT in __init__.py
   uint32_t last_connected_{0};
 
   // Slots [0, api_connection_count_) are populated; trailing slots are always nullptr.
@@ -344,8 +355,8 @@ class APIServer final : public Component,
 #endif
 
   // Group smaller types together
-  uint16_t port_{6053};
-  uint16_t batch_delay_{100};
+  uint16_t port_{6053};        // Keep in sync with DEFAULT_PORT in __init__.py
+  uint16_t batch_delay_{100};  // Keep in sync with DEFAULT_BATCH_DELAY in __init__.py
   // Connection limits - these defaults will be overridden by config values
   // from cv.SplitDefault in __init__.py which sets platform-specific defaults.
   uint8_t listen_backlog_{4};
@@ -358,6 +369,9 @@ class APIServer final : public Component,
 
 #ifdef USE_API_NOISE
   noise::NoiseContext noise_ctx_;
+#ifndef USE_API_NOISE_PSK_FROM_YAML
+  SavedNoisePsk saved_psk_{};  // backs noise_ctx_ for a runtime provisioned key
+#endif
   ESPPreferenceObject noise_pref_;
 #endif  // USE_API_NOISE
 };

esphome/components/api/list_entities.cpp

@@ -99,7 +99,8 @@ ListEntitiesIterator::ListEntitiesIterator(APIConnection *client) : client_(clie
 static constexpr uint8_t SERVICE_YIELD_INTERVAL = 3;
 
 bool ListEntitiesIterator::on_service(UserServiceDescriptor *service) {
-  auto resp = service->encode_list_service_response();
+  UserActionScratch scratch;
+  auto resp = service->encode_list_service_response(scratch);
   if (!this->client_->send_message(resp))
     return false;
   // at_ is this service's index

esphome/components/api/proto.cpp

@@ -195,6 +195,12 @@ void proto_check_bounds_failed(const uint8_t *pos, size_t bytes, const uint8_t *
   ESP_LOGE(TAG, "Proto encode bounds check failed in %s: need %zu bytes, %td available", caller, bytes, end - pos);
   abort();
 }
+void proto_check_encode_end(const uint8_t *end, const uint8_t *expected) {
+  if (end == expected)
+    return;
+  ESP_LOGE(TAG, "Proto encode ended %td bytes off the calculated size", end - expected);
+  abort();
+}
 void ProtoWriteBuffer::debug_check_bounds_(size_t bytes, const char *caller) {
   if (this->pos_ + bytes > this->buffer_->data() + this->buffer_->size()) {
     ESP_LOGE(TAG, "ProtoWriteBuffer bounds check failed in %s: bytes=%zu offset=%td buf_size=%zu", caller, bytes,
@@ -210,77 +216,78 @@ void ProtoWriteBuffer::debug_check_encode_size_(uint32_t field_id, uint32_t expe
 
 #endif
 
-void ProtoDecodableMessage::decode(const uint8_t *buffer, size_t length) {
+void ProtoDecodableMessage::decode_fields(void *msg, const uint8_t *buffer, size_t length, DecodeFieldFn field) {
   const uint8_t *ptr = buffer;
   const uint8_t *end = buffer + length;
 
-  while (ptr < end) {
-    // Parse field header - ptr < end guarantees len >= 1
+  // Single-byte varints dominate, so that case advances the cursor inline.
+  auto read_varint = [&](proto_varint_value_t &value) ESPHOME_ALWAYS_INLINE {
+    if (ptr == end)
+      return false;
+    if (*ptr < 0x80) [[likely]] {
+      value = *ptr++;
+      return true;
+    }
     auto res = ProtoVarInt::parse_non_empty(ptr, end - ptr);
-    if (!res.has_value()) {
+    if (!res.has_value())
+      return false;
+    value = res.value;
+    ptr += res.consumed;
+    return true;
+  };
+
+  while (ptr < end) {
+    proto_varint_value_t tag_value;
+    if (!read_varint(tag_value)) {
       ESP_LOGV(TAG, "Invalid field start at offset %ld", (long) (ptr - buffer));
       return;
     }
 
-    uint32_t tag = static_cast<uint32_t>(res.value);
+    uint32_t tag = static_cast<uint32_t>(tag_value);
     uint32_t field_type = tag & WIRE_TYPE_MASK;
-    uint32_t field_id = tag >> 3;
-    ptr += res.consumed;
+    // Length-delimited fields move this past the length prefix
+    const uint8_t *data = ptr;
+    proto_varint_value_t scalar;
 
-    switch (field_type) {
-      case WIRE_TYPE_VARINT: {  // VarInt
-        res = ProtoVarInt::parse(ptr, end - ptr);
-        if (!res.has_value()) {
-          ESP_LOGV(TAG, "Invalid VarInt at offset %ld", (long) (ptr - buffer));
-          return;
-        }
-        if (!this->decode_varint(field_id, res.value)) {
-          ESP_LOGV(TAG, "Cannot decode VarInt field %" PRIu32 " with value %" PRIu64 "!", field_id,
-                   static_cast<uint64_t>(res.value));
-        }
-        ptr += res.consumed;
-        break;
-      }
-      case WIRE_TYPE_LENGTH_DELIMITED: {  // Length-delimited
-        res = ProtoVarInt::parse(ptr, end - ptr);
-        if (!res.has_value()) {
-          ESP_LOGV(TAG, "Invalid Length Delimited at offset %ld", (long) (ptr - buffer));
-          return;
-        }
-        uint32_t field_length = static_cast<uint32_t>(res.value);
-        ptr += res.consumed;
-        if (field_length > static_cast<size_t>(end - ptr)) {
-          ESP_LOGV(TAG, "Out-of-bounds Length Delimited at offset %ld", (long) (ptr - buffer));
-          return;
-        }
-        if (!this->decode_length(field_id, ProtoLengthDelimited(ptr, field_length))) {
-          ESP_LOGV(TAG, "Cannot decode Length Delimited field %" PRIu32 "!", field_id);
-        }
-        ptr += field_length;
-        break;
-      }
-      case WIRE_TYPE_FIXED32: {  // 32-bit
-        if (end - ptr < 4) {
-          ESP_LOGV(TAG, "Out-of-bounds Fixed32-bit at offset %ld", (long) (ptr - buffer));
-          return;
-        }
-        uint32_t val;
-#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-        // Protobuf fixed32 is little-endian — direct load on LE platforms
-        memcpy(&val, ptr, 4);
-#else
-        val = encode_uint32(ptr[3], ptr[2], ptr[1], ptr[0]);
-#endif
-        if (!this->decode_32bit(field_id, Proto32Bit(val))) {
-          ESP_LOGV(TAG, "Cannot decode 32-bit field %" PRIu32 " with value %" PRIu32 "!", field_id, val);
-        }
-        ptr += 4;
-        break;
-      }
-      default:
-        ESP_LOGV(TAG, "Invalid field type %" PRIu32 " at offset %ld", field_type, (long) (ptr - buffer));
+    if (field_type == WIRE_TYPE_VARINT) [[likely]] {
+      if (!read_varint(scalar)) {
+        ESP_LOGV(TAG, "Invalid VarInt at offset %ld", (long) (ptr - buffer));
         return;
+      }
+    } else {
+      switch (field_type) {
+        case WIRE_TYPE_LENGTH_DELIMITED: {
+          proto_varint_value_t length_value;
+          if (!read_varint(length_value)) {
+            ESP_LOGV(TAG, "Invalid Length Delimited at offset %ld", (long) (ptr - buffer));
+            return;
+          }
+          uint32_t field_length = static_cast<uint32_t>(length_value);
+          if (field_length > static_cast<size_t>(end - ptr)) {
+            ESP_LOGV(TAG, "Out-of-bounds Length Delimited at offset %ld", (long) (ptr - buffer));
+            return;
+          }
+          data = ptr;
+          scalar = field_length;
+          ptr += field_length;
+          break;
+        }
+        case WIRE_TYPE_FIXED32: {
+          if (end - ptr < 4) {
+            ESP_LOGV(TAG, "Out-of-bounds Fixed32-bit at offset %ld", (long) (ptr - buffer));
+            return;
+          }
+          // Byte loads instead of memcpy: ESP-IDF passes -fno-builtin-memcpy, which made this a call
+          scalar = encode_uint32(ptr[3], ptr[2], ptr[1], ptr[0]);
+          ptr += 4;
+          break;
+        }
+        default:
+          ESP_LOGV(TAG, "Invalid field type %" PRIu32 " at offset %ld", field_type, (long) (ptr - buffer));
+          return;
+      }
     }
+    field(msg, tag, data, scalar);
   }
 }
 

esphome/components/api/proto.h

@@ -10,6 +10,7 @@
 
 #include <cassert>
 #include <cstring>
+#include <type_traits>
 #include <vector>
 
 #ifdef ESPHOME_LOG_HAS_VERY_VERBOSE
@@ -170,40 +171,43 @@ class ProtoVarInt {
 class ProtoMessage;
 class ProtoSize;
 
-class ProtoLengthDelimited {
+/// Case label for decode_field(): the wire tag of a field, so a field that arrives with another wire
+/// type matches no case.
+constexpr uint32_t proto_tag(uint32_t field_id, uint32_t wire_type) { return (field_id << 3) | wire_type; }
+
+/// One decoded field: the payload pointer and a scalar holding the varint or fixed32 value, or the
+/// length of a length-delimited field. The wire type in the tag says which applies; accessors do not check.
+class ProtoFieldValue {
  public:
-  explicit ProtoLengthDelimited(const uint8_t *value, size_t length) : value_(value), length_(length) {}
-  std::string as_string() const { return std::string(reinterpret_cast<const char *>(this->value_), this->length_); }
+  ProtoFieldValue(const uint8_t *data, proto_varint_value_t scalar) : data_(data), scalar_(scalar) {}
 
-  // Direct access to raw data without string allocation
-  const uint8_t *data() const { return this->value_; }
-  size_t size() const { return this->length_; }
+  proto_varint_value_t as_varint() const { return this->scalar_; }
+  // A bool is sent as 0 or 1, so the low word is enough and saves a second compare with 64 bit varints
+  bool as_bool() const { return static_cast<uint32_t>(this->scalar_) != 0; }
 
-  /// Decode the length-delimited data into a message instance.
+  // Length-delimited accessors
+  const uint8_t *data() const { return this->data_; }
+  size_t size() const { return static_cast<size_t>(this->scalar_); }
+  std::string as_string() const { return std::string(reinterpret_cast<const char *>(this->data_), this->size()); }
+  /// Decode the length-delimited payload into a message instance.
   /// Template preserves concrete type so decode() resolves statically.
-  template<typename T> void decode_to_message(T &msg) const;
+  template<typename T> void decode_to_message(T &msg) const { msg.decode(this->data_, this->size()); }
 
- protected:
-  const uint8_t *const value_;
-  const size_t length_;
-};
-
-class Proto32Bit {
- public:
-  explicit Proto32Bit(uint32_t value) : value_(value) {}
-  uint32_t as_fixed32() const { return this->value_; }
-  int32_t as_sfixed32() const { return static_cast<int32_t>(this->value_); }
+  // Fixed32 accessors
+  uint32_t as_fixed32() const { return static_cast<uint32_t>(this->scalar_); }
+  int32_t as_sfixed32() const { return static_cast<int32_t>(this->as_fixed32()); }
   float as_float() const {
     union {
       uint32_t raw;
       float value;
     } s{};
-    s.raw = this->value_;
+    s.raw = this->as_fixed32();
     return s.value;
   }
 
- protected:
-  const uint32_t value_;
+ private:
+  const uint8_t *data_;
+  proto_varint_value_t scalar_;
 };
 
 // NOTE: Proto64Bit class removed - wire type 1 (64-bit fixed) not supported
@@ -221,6 +225,9 @@ class Proto32Bit {
       proto_check_bounds_failed(pos, n, proto_debug_end_, __builtin_FUNCTION()); \
   } while (0)
 void proto_check_bounds_failed(const uint8_t *pos, size_t bytes, const uint8_t *end, const char *caller);
+/// Aborts unless an encode body ended exactly where calculate_size() promised. A plain check rather than
+/// assert(), so NDEBUG cannot switch it off.
+void proto_check_encode_end(const uint8_t *end, const uint8_t *expected);
 #else
 #define PROTO_ENCODE_DEBUG_PARAM
 #define PROTO_ENCODE_DEBUG_ARG
@@ -252,7 +259,7 @@ class ProtoWriteBuffer {
    *
    * Following https://protobuf.dev/programming-guides/encoding/#structure
    */
-  void encode_field_raw(uint32_t field_id, uint32_t type) { this->encode_varint_raw((field_id << 3) | type); }
+  void encode_field_raw(uint32_t field_id, uint32_t type) { this->encode_varint_raw(proto_tag(field_id, type)); }
   /// Single-pass encode for repeated submessage elements.
   /// Thin template wrapper; all buffer work is in the non-template core.
   template<typename T> void encode_sub_message(uint32_t field_id, const T &value);
@@ -287,19 +294,31 @@ class ProtoWriteBuffer {
   uint8_t *pos_;
 };
 
+// A four byte unaligned store is a memcpy call on ESP-IDF (-fno-builtin-memcpy) and on ARM cores without
+// unaligned access (Cortex-M0+, ARM9), so those targets share one outlined byte store helper per fixed32
+// field. Elsewhere the write inlines to a single store, or on ESP8266 to a few stores that measured
+// faster than a call, so it stays inline.
+#if defined(USE_ESP32) || (defined(__arm__) && !defined(__ARM_FEATURE_UNALIGNED))
+#define PROTO_OUTLINE_FOR_SIZE __attribute__((noinline))
+#define PROTO_FIXED32_BYTE_STORES true
+#else
+#define PROTO_OUTLINE_FOR_SIZE inline
+#define PROTO_FIXED32_BYTE_STORES false
+#endif
+
 // Varint encoding thresholds — used by both proto_encode_* free functions and ProtoSize.
 constexpr uint32_t VARINT_MAX_1_BYTE = 1 << 7;   // 128
 constexpr uint32_t VARINT_MAX_2_BYTE = 1 << 14;  // 16384
 
-/// Static encode helpers for generated encode() functions.
-/// Generated code hoists buffer.pos_ into a local uint8_t *__restrict__ pos,
-/// then calls these methods which take pos by reference. No struct, no overhead.
-/// For sub-messages, pos is synced back to buffer before the call and reloaded after.
+/// Static encode helpers for the generated encode bodies. Each takes the write cursor by value and
+/// returns it advanced, so outlined calls at -Os chain through the return register instead of a
+/// stack slot. Helpers without a _force suffix skip fields holding the proto3 default.
 class ProtoEncode {
  public:
   /// Write a multi-byte varint directly through a pos pointer.
   template<typename T>
-  static inline void encode_varint_raw_loop(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, T value) {
+  [[nodiscard]] static inline uint8_t *encode_varint_raw_loop(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                              T value) {
     do {
       PROTO_ENCODE_CHECK_BOUNDS(pos, 1);
       *pos++ = static_cast<uint8_t>(value | 0x80);
@@ -307,48 +326,49 @@ class ProtoEncode {
     } while (value > 0x7F);
     PROTO_ENCODE_CHECK_BOUNDS(pos, 1);
     *pos++ = static_cast<uint8_t>(value);
+    return pos;
   }
-  static inline void ESPHOME_ALWAYS_INLINE encode_varint_raw(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM,
-                                                             uint32_t value) {
+  [[nodiscard]] static inline uint8_t *ESPHOME_ALWAYS_INLINE
+  encode_varint_raw(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM, uint32_t value) {
     if (value < VARINT_MAX_1_BYTE) [[likely]] {
       PROTO_ENCODE_CHECK_BOUNDS(pos, 1);
       *pos++ = static_cast<uint8_t>(value);
-      return;
+      return pos;
     }
-    encode_varint_raw_loop(pos PROTO_ENCODE_DEBUG_ARG, value);
+    return encode_varint_raw_loop(pos PROTO_ENCODE_DEBUG_ARG, value);
   }
   /// Encode a varint that is expected to be 1-2 bytes (e.g. zigzag RSSI, small lengths).
-  static inline void ESPHOME_ALWAYS_INLINE encode_varint_raw_short(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM,
-                                                                   uint32_t value) {
+  [[nodiscard]] static inline uint8_t *ESPHOME_ALWAYS_INLINE
+  encode_varint_raw_short(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM, uint32_t value) {
     if (value < VARINT_MAX_1_BYTE) [[likely]] {
       PROTO_ENCODE_CHECK_BOUNDS(pos, 1);
       *pos++ = static_cast<uint8_t>(value);
-      return;
+      return pos;
     }
     if (value < VARINT_MAX_2_BYTE) [[likely]] {
       PROTO_ENCODE_CHECK_BOUNDS(pos, 2);
       *pos++ = static_cast<uint8_t>(value | 0x80);
       *pos++ = static_cast<uint8_t>(value >> 7);
-      return;
+      return pos;
     }
-    encode_varint_raw_loop(pos PROTO_ENCODE_DEBUG_ARG, value);
+    return encode_varint_raw_loop(pos PROTO_ENCODE_DEBUG_ARG, value);
   }
-  static inline void ESPHOME_ALWAYS_INLINE encode_varint_raw_64(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM,
-                                                                uint64_t value) {
+  [[nodiscard]] static inline uint8_t *ESPHOME_ALWAYS_INLINE
+  encode_varint_raw_64(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM, uint64_t value) {
     if (value < VARINT_MAX_1_BYTE) [[likely]] {
       PROTO_ENCODE_CHECK_BOUNDS(pos, 1);
       *pos++ = static_cast<uint8_t>(value);
-      return;
+      return pos;
     }
-    encode_varint_raw_loop(pos PROTO_ENCODE_DEBUG_ARG, value);
+    return encode_varint_raw_loop(pos PROTO_ENCODE_DEBUG_ARG, value);
   }
   /// Encode a 48-bit MAC address (stored in a uint64) as varint.
   /// Real MAC addresses occupy the full 48 bits (OUI in upper 24), so the
   /// fast path -- any non-zero bit in the top 6 of 48 -- emits exactly 7 bytes
   /// with no per-byte branch. Falls back to the general loop otherwise.
   /// Caller must guarantee value fits in 48 bits (checked in debug builds).
-  static inline void ESPHOME_ALWAYS_INLINE encode_varint_raw_48bit(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM,
-                                                                   uint64_t value) {
+  [[nodiscard]] static inline uint8_t *ESPHOME_ALWAYS_INLINE
+  encode_varint_raw_48bit(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM, uint64_t value) {
 #ifdef ESPHOME_DEBUG_API
     assert(value < (1ULL << (MAC_ADDRESS_SIZE * 8)) && "encode_varint_raw_48bit: value exceeds 48 bits");
 #endif
@@ -363,38 +383,39 @@ class ProtoEncode {
       pos[4] = static_cast<uint8_t>((value >> 28) | 0x80);
       pos[5] = static_cast<uint8_t>((value >> 35) | 0x80);
       pos[6] = static_cast<uint8_t>(value >> 42);
-      pos += 7;
-      return;
+      return pos + 7;
     }
-    encode_varint_raw_64(pos PROTO_ENCODE_DEBUG_ARG, value);
+    return encode_varint_raw_64(pos PROTO_ENCODE_DEBUG_ARG, value);
   }
-  static inline void ESPHOME_ALWAYS_INLINE encode_field_raw(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM,
-                                                            uint32_t field_id, uint32_t type) {
-    encode_varint_raw(pos PROTO_ENCODE_DEBUG_ARG, (field_id << 3) | type);
+  [[nodiscard]] static inline uint8_t *ESPHOME_ALWAYS_INLINE
+  encode_field_raw(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id, uint32_t type) {
+    return encode_varint_raw(pos PROTO_ENCODE_DEBUG_ARG, proto_tag(field_id, type));
   }
   /// Write a single precomputed tag byte. Tag must be < 128.
-  static inline void ESPHOME_ALWAYS_INLINE write_raw_byte(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM,
-                                                          uint8_t b) {
+  [[nodiscard]] static inline uint8_t *ESPHOME_ALWAYS_INLINE
+  write_raw_byte(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM, uint8_t b) {
     PROTO_ENCODE_CHECK_BOUNDS(pos, 1);
     *pos++ = b;
+    return pos;
   }
   /// Reserve one byte for later backpatch (e.g., sub-message length).
   /// Advances pos past the reserved byte without writing a value.
-  static inline void ESPHOME_ALWAYS_INLINE reserve_byte(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM) {
+  [[nodiscard]] static inline uint8_t *ESPHOME_ALWAYS_INLINE
+  reserve_byte(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM) {
     PROTO_ENCODE_CHECK_BOUNDS(pos, 1);
-    pos++;
+    return pos + 1;
   }
   /// Write raw bytes to the buffer (no tag, no length prefix).
-  static inline void ESPHOME_ALWAYS_INLINE encode_raw(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM,
-                                                      const void *data, size_t len) {
+  [[nodiscard]] static inline uint8_t *ESPHOME_ALWAYS_INLINE
+  encode_raw(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM, const void *data, size_t len) {
     PROTO_ENCODE_CHECK_BOUNDS(pos, len);
     std::memcpy(pos, data, len);
-    pos += len;
+    return pos + len;
   }
   /// Encode tag + 1-byte length + raw string data. For strings with max_data_length < 128.
   /// Tag must be a single-byte varint (< 128). Always encodes (no zero check).
-  static inline void encode_short_string_force(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint8_t tag,
-                                               const StringRef &ref) {
+  [[nodiscard]] static inline uint8_t *encode_short_string_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                                 uint8_t tag, const StringRef &ref) {
 #ifdef ESPHOME_DEBUG_API
     assert(ref.size() < 128 && "encode_short_string_force: string exceeds max_data_length < 128");
 #endif
@@ -402,137 +423,191 @@ class ProtoEncode {
     pos[0] = tag;
     pos[1] = static_cast<uint8_t>(ref.size());
     std::memcpy(pos + 2, ref.c_str(), ref.size());
-    pos += 2 + ref.size();
+    return pos + 2 + ref.size();
   }
-  /// Write a precomputed tag byte + 32-bit value in one operation.
-  static inline void ESPHOME_ALWAYS_INLINE write_tag_and_fixed32(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM,
-                                                                 uint8_t tag, uint32_t value) {
+  /// Write a precomputed tag byte + 32-bit value. Outlined on embedded: one copy beats inline stores per field.
+  [[nodiscard]] static PROTO_OUTLINE_FOR_SIZE uint8_t *write_tag_and_fixed32(
+      uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM, uint8_t tag, uint32_t value) {
     PROTO_ENCODE_CHECK_BOUNDS(pos, 5);
     pos[0] = tag;
-#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-    std::memcpy(pos + 1, &value, 4);
-#else
-    pos[1] = static_cast<uint8_t>(value & 0xFF);
-    pos[2] = static_cast<uint8_t>((value >> 8) & 0xFF);
-    pos[3] = static_cast<uint8_t>((value >> 16) & 0xFF);
-    pos[4] = static_cast<uint8_t>((value >> 24) & 0xFF);
-#endif
-    pos += 5;
+    write_fixed32_le(pos + 1, value);
+    return pos + 5;
   }
-  static inline void encode_string(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id,
-                                   const char *string, size_t len, bool force = false) {
-    if (len == 0 && !force)
-      return;
-    encode_field_raw(pos PROTO_ENCODE_DEBUG_ARG, field_id, 2);  // type 2: Length-delimited string
+  [[nodiscard]] static inline uint8_t *encode_string_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                           uint32_t field_id, const char *string, size_t len) {
+    pos = encode_field_raw(pos PROTO_ENCODE_DEBUG_ARG, field_id, 2);  // type 2: Length-delimited string
     // NOLINTNEXTLINE(readability-inconsistent-ifelse-braces) -- false positive on [[likely]] attribute
     if (len < VARINT_MAX_1_BYTE) [[likely]] {
       PROTO_ENCODE_CHECK_BOUNDS(pos, 1 + len);
       *pos++ = static_cast<uint8_t>(len);
     } else {
-      encode_varint_raw_loop(pos PROTO_ENCODE_DEBUG_ARG, len);
+      pos = encode_varint_raw_loop(pos PROTO_ENCODE_DEBUG_ARG, len);
       PROTO_ENCODE_CHECK_BOUNDS(pos, len);
     }
     std::memcpy(pos, string, len);
-    pos += len;
+    return pos + len;
   }
-  static inline void encode_string(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id,
-                                   const std::string &value, bool force = false) {
-    encode_string(pos PROTO_ENCODE_DEBUG_ARG, field_id, value.data(), value.size(), force);
+  [[nodiscard]] static inline uint8_t *encode_string(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                     uint32_t field_id, const char *string, size_t len) {
+    if (len == 0)
+      return pos;
+    return encode_string_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, string, len);
   }
-  static inline void encode_string(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id,
-                                   const StringRef &ref, bool force = false) {
-    encode_string(pos PROTO_ENCODE_DEBUG_ARG, field_id, ref.c_str(), ref.size(), force);
+  [[nodiscard]] static inline uint8_t *encode_string_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                           uint32_t field_id, const std::string &value) {
+    return encode_string_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, value.data(), value.size());
   }
-  static inline void encode_bytes(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id,
-                                  const uint8_t *data, size_t len, bool force = false) {
-    encode_string(pos PROTO_ENCODE_DEBUG_ARG, field_id, reinterpret_cast<const char *>(data), len, force);
+  [[nodiscard]] static inline uint8_t *encode_string(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                     uint32_t field_id, const StringRef &ref) {
+    return encode_string(pos PROTO_ENCODE_DEBUG_ARG, field_id, ref.c_str(), ref.size());
   }
-  static inline void encode_uint32(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id,
-                                   uint32_t value, bool force = false) {
-    if (value == 0 && !force)
-      return;
-    encode_field_raw(pos PROTO_ENCODE_DEBUG_ARG, field_id, 0);
-    encode_varint_raw(pos PROTO_ENCODE_DEBUG_ARG, value);
+  [[nodiscard]] static inline uint8_t *encode_string_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                           uint32_t field_id, const StringRef &ref) {
+    return encode_string_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, ref.c_str(), ref.size());
   }
-  static inline void encode_uint64(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id,
-                                   uint64_t value, bool force = false) {
-    if (value == 0 && !force)
-      return;
-    encode_field_raw(pos PROTO_ENCODE_DEBUG_ARG, field_id, 0);
-    encode_varint_raw_64(pos PROTO_ENCODE_DEBUG_ARG, value);
+  [[nodiscard]] static inline uint8_t *encode_bytes(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                    uint32_t field_id, const uint8_t *data, size_t len) {
+    return encode_string(pos PROTO_ENCODE_DEBUG_ARG, field_id, reinterpret_cast<const char *>(data), len);
   }
-  static inline void encode_bool(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id, bool value,
-                                 bool force = false) {
-    if (!value && !force)
-      return;
-    encode_field_raw(pos PROTO_ENCODE_DEBUG_ARG, field_id, 0);
+  [[nodiscard]] static inline uint8_t *encode_bytes_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                          uint32_t field_id, const uint8_t *data, size_t len) {
+    return encode_string_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, reinterpret_cast<const char *>(data), len);
+  }
+  [[nodiscard]] static inline uint8_t *encode_uint32_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                           uint32_t field_id, uint32_t value) {
+    pos = encode_field_raw(pos PROTO_ENCODE_DEBUG_ARG, field_id, 0);
+    return encode_varint_raw(pos PROTO_ENCODE_DEBUG_ARG, value);
+  }
+  [[nodiscard]] static inline uint8_t *encode_uint32(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                     uint32_t field_id, uint32_t value) {
+    if (value == 0)
+      return pos;
+    return encode_uint32_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, value);
+  }
+  [[nodiscard]] static inline uint8_t *encode_uint64_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                           uint32_t field_id, uint64_t value) {
+    pos = encode_field_raw(pos PROTO_ENCODE_DEBUG_ARG, field_id, 0);
+    return encode_varint_raw_64(pos PROTO_ENCODE_DEBUG_ARG, value);
+  }
+  [[nodiscard]] static inline uint8_t *encode_uint64(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                     uint32_t field_id, uint64_t value) {
+    if (value == 0)
+      return pos;
+    return encode_uint64_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, value);
+  }
+  [[nodiscard]] static inline uint8_t *encode_bool_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                         uint32_t field_id, bool value) {
+    pos = encode_field_raw(pos PROTO_ENCODE_DEBUG_ARG, field_id, 0);
     PROTO_ENCODE_CHECK_BOUNDS(pos, 1);
     *pos++ = value ? 0x01 : 0x00;
+    return pos;
   }
-  static inline void encode_fixed32(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id,
-                                    uint32_t value, bool force = false) {
-    if (value == 0 && !force)
-      return;
-    encode_field_raw(pos PROTO_ENCODE_DEBUG_ARG, field_id, 5);
+  [[nodiscard]] static inline uint8_t *encode_bool(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                   uint32_t field_id, bool value) {
+    if (!value)
+      return pos;
+    return encode_bool_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, value);
+  }
+  /// Tag + fixed32 for multi-byte tags; single-byte tags use write_tag_and_fixed32.
+  [[nodiscard]] static PROTO_OUTLINE_FOR_SIZE uint8_t *encode_fixed32_force(
+      uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id, uint32_t value) {
+    pos = encode_field_raw(pos PROTO_ENCODE_DEBUG_ARG, field_id, 5);
     PROTO_ENCODE_CHECK_BOUNDS(pos, 4);
-#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-    std::memcpy(pos, &value, 4);
-    pos += 4;
-#else
-    *pos++ = (value >> 0) & 0xFF;
-    *pos++ = (value >> 8) & 0xFF;
-    *pos++ = (value >> 16) & 0xFF;
-    *pos++ = (value >> 24) & 0xFF;
-#endif
+    write_fixed32_le(pos, value);
+    return pos + 4;
+  }
+  [[nodiscard]] static inline uint8_t *encode_fixed32(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                      uint32_t field_id, uint32_t value) {
+    if (value == 0)
+      return pos;
+    return encode_fixed32_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, value);
   }
   // NOTE: Wire type 1 (64-bit fixed: double, fixed64, sfixed64) is intentionally
   // not supported to reduce overhead on embedded systems. All ESPHome devices are
   // 32-bit microcontrollers where 64-bit operations are expensive. If 64-bit support
   // is needed in the future, the necessary encoding/decoding functions must be added.
-  static inline void encode_float(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id, float value,
-                                  bool force = false) {
-    uint32_t raw = float_to_raw(value);
-    if (raw == 0 && !force)
-      return;
-    encode_fixed32(pos PROTO_ENCODE_DEBUG_ARG, field_id, raw);
+  [[nodiscard]] static inline uint8_t *encode_float(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                    uint32_t field_id, float value) {
+    return encode_fixed32(pos PROTO_ENCODE_DEBUG_ARG, field_id, float_to_raw(value));
   }
-  static inline void encode_int32(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id, int32_t value,
-                                  bool force = false) {
+  [[nodiscard]] static inline uint8_t *encode_float_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                          uint32_t field_id, float value) {
+    return encode_fixed32_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, float_to_raw(value));
+  }
+  [[nodiscard]] static inline uint8_t *encode_int32_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                          uint32_t field_id, int32_t value) {
     if (value < 0) {
       // negative int32 is always 10 byte long
-      encode_uint64(pos PROTO_ENCODE_DEBUG_ARG, field_id, static_cast<uint64_t>(value), force);
-      return;
+      return encode_uint64_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, static_cast<uint64_t>(value));
     }
-    encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, field_id, static_cast<uint32_t>(value), force);
+    return encode_uint32_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, static_cast<uint32_t>(value));
   }
-  static inline void encode_int64(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id, int64_t value,
-                                  bool force = false) {
-    encode_uint64(pos PROTO_ENCODE_DEBUG_ARG, field_id, static_cast<uint64_t>(value), force);
+  [[nodiscard]] static inline uint8_t *encode_int32(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                    uint32_t field_id, int32_t value) {
+    if (value == 0)
+      return pos;
+    return encode_int32_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, value);
   }
-  static inline void encode_sint32(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id,
-                                   int32_t value, bool force = false) {
-    encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, field_id, encode_zigzag32(value), force);
+  [[nodiscard]] static inline uint8_t *encode_int64(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                    uint32_t field_id, int64_t value) {
+    return encode_uint64(pos PROTO_ENCODE_DEBUG_ARG, field_id, static_cast<uint64_t>(value));
   }
-  static inline void encode_sint64(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, uint32_t field_id,
-                                   int64_t value, bool force = false) {
-    encode_uint64(pos PROTO_ENCODE_DEBUG_ARG, field_id, encode_zigzag64(value), force);
+  [[nodiscard]] static inline uint8_t *encode_int64_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                          uint32_t field_id, int64_t value) {
+    return encode_uint64_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, static_cast<uint64_t>(value));
   }
-  /// Sub-message encoding: sync pos to buffer, delegate, get pos from return value.
+  [[nodiscard]] static inline uint8_t *encode_sint32(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                     uint32_t field_id, int32_t value) {
+    return encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, field_id, encode_zigzag32(value));
+  }
+  [[nodiscard]] static inline uint8_t *encode_sint32_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                           uint32_t field_id, int32_t value) {
+    return encode_uint32_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, encode_zigzag32(value));
+  }
+  [[nodiscard]] static inline uint8_t *encode_sint64(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                     uint32_t field_id, int64_t value) {
+    return encode_uint64(pos PROTO_ENCODE_DEBUG_ARG, field_id, encode_zigzag64(value));
+  }
+  [[nodiscard]] static inline uint8_t *encode_sint64_force(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                           uint32_t field_id, int64_t value) {
+    return encode_uint64_force(pos PROTO_ENCODE_DEBUG_ARG, field_id, encode_zigzag64(value));
+  }
+  /// Sub-message encoding: sync pos to buffer, delegate, read the cursor back.
   template<typename T>
-  static inline void encode_sub_message(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM, ProtoWriteBuffer &buffer,
-                                        uint32_t field_id, const T &value) {
+  [[nodiscard]] static inline uint8_t *encode_sub_message(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                          ProtoWriteBuffer &buffer, uint32_t field_id, const T &value) {
     buffer.set_pos(pos);
     buffer.encode_sub_message(field_id, value);
-    pos = buffer.get_pos();
+    return buffer.get_pos();
   }
   template<typename T>
-  static inline void encode_optional_sub_message(uint8_t *__restrict__ &pos PROTO_ENCODE_DEBUG_PARAM,
-                                                 ProtoWriteBuffer &buffer, uint32_t field_id, const T &value) {
+  [[nodiscard]] static inline uint8_t *encode_optional_sub_message(uint8_t *__restrict__ pos PROTO_ENCODE_DEBUG_PARAM,
+                                                                   ProtoWriteBuffer &buffer, uint32_t field_id,
+                                                                   const T &value) {
     buffer.set_pos(pos);
     buffer.encode_optional_sub_message(field_id, value);
-    pos = buffer.get_pos();
+    return buffer.get_pos();
+  }
+
+ private:
+  /// Unaligned little endian store of four bytes: byte stores where the outlined helper lives (ESP-IDF, ARM
+  /// without unaligned access), otherwise a memcpy the compiler folds into one store. Callers bounds check
+  /// and advance the cursor themselves.
+  static inline void ESPHOME_ALWAYS_INLINE write_fixed32_le(uint8_t *__restrict__ pos, uint32_t value) {
+    if constexpr (PROTO_FIXED32_BYTE_STORES) {
+      // Spelled out so the outlined helper does not itself become a memcpy call
+      pos[0] = static_cast<uint8_t>(value);
+      pos[1] = static_cast<uint8_t>(value >> 8);
+      pos[2] = static_cast<uint8_t>(value >> 16);
+      pos[3] = static_cast<uint8_t>(value >> 24);
+    } else {
+      const uint32_t le = convert_little_endian(value);
+      __builtin_memcpy(pos, &le, 4);
+    }
   }
 };
+#undef PROTO_OUTLINE_FOR_SIZE
+#undef PROTO_FIXED32_BYTE_STORES
 
 #ifdef HAS_PROTO_MESSAGE_DUMP
 /**
@@ -624,11 +699,12 @@ class DumpBuffer {
 
 class ProtoMessage {
  public:
-  // Non-virtual defaults for messages with no fields.
-  // Concrete message classes hide these with their own implementations.
-  // All call sites use templates to preserve the concrete type, so virtual
-  // dispatch is not needed. This eliminates per-message vtable entries for
-  // encode/calculate_size, saving ~1.3 KB of flash across all message types.
+  // Non-virtual defaults for messages with no fields; generated classes hide all four. The
+  // static encode_msg/calc_size_msg take const void * so &T::encode_msg needs no thunk.
+  static uint8_t *encode_msg(const void *self, ProtoWriteBuffer &buffer PROTO_ENCODE_DEBUG_PARAM) {
+    return buffer.get_pos();
+  }
+  static uint32_t calc_size_msg(const void *self) { return 0; }
   uint8_t *encode(ProtoWriteBuffer &buffer PROTO_ENCODE_DEBUG_PARAM) const { return buffer.get_pos(); }
   uint32_t calculate_size() const { return 0; }
 #ifdef HAS_PROTO_MESSAGE_DUMP
@@ -648,7 +724,13 @@ class ProtoMessage {
 // Base class for messages that support decoding
 class ProtoDecodableMessage : public ProtoMessage {
  public:
-  void decode(const uint8_t *buffer, size_t length);
+  /// Stores one decoded field into \p msg; generated per message type. \p scalar is the varint or
+  /// fixed32 value, or the length of the length-delimited payload at \p data. An unknown field or
+  /// wrong wire type matches no case and is skipped.
+  using DecodeFieldFn = void (*)(void *msg, uint32_t tag, const uint8_t *data, proto_varint_value_t scalar);
+  /// Walk \p buffer and hand every field to \p field. The generated decode() passes the message's
+  /// own decode_field, so decodable messages carry no vtable.
+  static void decode_fields(void *msg, const uint8_t *buffer, size_t length, DecodeFieldFn field);
 
   /**
    * Count occurrences of a repeated field in a protobuf buffer.
@@ -660,14 +742,15 @@ class ProtoDecodableMessage : public ProtoMessage {
    * @return Number of times the field appears in the buffer
    */
   static uint32_t count_repeated_field(const uint8_t *buffer, size_t length, uint32_t target_field_id);
-
- protected:
-  ~ProtoDecodableMessage() = default;
-  virtual bool decode_varint(uint32_t field_id, proto_varint_value_t value) { return false; }
-  virtual bool decode_length(uint32_t field_id, ProtoLengthDelimited value) { return false; }
-  virtual bool decode_32bit(uint32_t field_id, Proto32Bit value) { return false; }
-  // NOTE: decode_64bit removed - wire type 1 not supported
+  // The destructor stays accessible on purpose: the generated messages are aggregates that brace
+  // initialise sub message members, which copies a base temporary. That trades away the compile time
+  // guard against deleting through this type; messages are stack locals and never owned through a base
+  // pointer. ProtoMessage keeps its guard for the dump builds.
 };
+#ifndef HAS_PROTO_MESSAGE_DUMP
+// decode() passes decode_field explicitly, so nothing here may add a vtable
+static_assert(!std::is_polymorphic_v<ProtoDecodableMessage>, "decodable messages carry no vtable");
+#endif
 
 class ProtoSize {
  public:
@@ -684,11 +767,6 @@ class ProtoSize {
     return value < VARINT_THRESHOLD_1_BYTE ? 1 : (value < VARINT_THRESHOLD_2_BYTE ? 2 : 3);
   }
 
-  // Varint encoded length for an 8-bit value (1 or 2 bytes).
-  static constexpr inline uint8_t ESPHOME_ALWAYS_INLINE varint8(uint8_t value) {
-    return value < VARINT_THRESHOLD_1_BYTE ? 1 : 2;
-  }
-
   /**
    * @brief Calculates the size in bytes needed to encode a uint32_t value as a varint
    *
@@ -797,7 +875,7 @@ class ProtoSize {
    * @return The number of bytes needed to encode the field ID and wire type
    */
   static constexpr uint32_t field(uint32_t field_id, uint32_t type) {
-    uint32_t tag = (field_id << 3) | (type & WIRE_TYPE_MASK);
+    uint32_t tag = proto_tag(field_id, type & WIRE_TYPE_MASK);
     return varint(tag);
   }
 
@@ -881,24 +959,14 @@ class ProtoSize {
 
 // Implementation of methods that depend on ProtoSize being fully defined
 
-// Encode thunk — converts void* back to concrete type for direct encode() call
-template<typename T> uint8_t *proto_encode_msg(const void *msg, ProtoWriteBuffer &buf PROTO_ENCODE_DEBUG_PARAM) {
-  return static_cast<const T *>(msg)->encode(buf PROTO_ENCODE_DEBUG_ARG);
-}
-
 // Thin template wrapper; delegates to non-template core in proto.cpp.
 template<typename T> inline void ProtoWriteBuffer::encode_sub_message(uint32_t field_id, const T &value) {
-  this->encode_sub_message(field_id, &value, &proto_encode_msg<T>);
+  this->encode_sub_message(field_id, &value, &T::encode_msg);
 }
 
 // Thin template wrapper; delegates to non-template core.
 template<typename T> inline void ProtoWriteBuffer::encode_optional_sub_message(uint32_t field_id, const T &value) {
-  this->encode_optional_sub_message(field_id, value.calculate_size(), &value, &proto_encode_msg<T>);
-}
-
-// Template decode_to_message - preserves concrete type so decode() resolves statically
-template<typename T> void ProtoLengthDelimited::decode_to_message(T &msg) const {
-  msg.decode(this->value_, this->length_);
+  this->encode_optional_sub_message(field_id, T::calc_size_msg(&value), &value, &T::encode_msg);
 }
 
 template<typename T> const char *proto_enum_to_string(T value);

esphome/components/api/subscribe_state.h

@@ -4,7 +4,6 @@
 #ifdef USE_API
 #include "esphome/core/component.h"
 #include "esphome/core/component_iterator.h"
-#include "esphome/core/controller.h"
 namespace esphome::api {
 
 class APIConnection;

esphome/components/api/user_services.cpp

@@ -1,9 +1,52 @@
 #include "user_services.h"
+#include "esphome/core/hal.h"
 #include "esphome/core/log.h"
 #include "esphome/core/string_ref.h"
 
 namespace esphome::api {
 
+StringRef UserServiceStatic::str_(size_t idx, std::span<char> &scratch) const {
+  const char *s = progmem_read_ptr(&this->strings_[idx]);
+  if (s == nullptr)
+    return {};
+#ifdef USE_ESP8266
+  // Codegen sizes the scratch buffer for the largest service; the bound only guards other callers
+  if (scratch.empty())
+    return {};
+  size_t len = strnlen_P(s, scratch.size() - 1);
+  progmem_memcpy(scratch.data(), s, len);
+  scratch[len] = '\0';
+  StringRef ref(scratch.data(), len);
+  scratch = scratch.subspan(len + 1);
+  return ref;
+#else
+  return StringRef(s);
+#endif
+}
+
+ListEntitiesServicesResponse UserServiceStatic::encode_list_service_response_(
+    std::span<const enums::ServiceArgType> arg_types, std::span<char> scratch) const {
+  ListEntitiesServicesResponse msg;
+  msg.name = this->str_(0, scratch);
+  msg.key = this->key_;
+  msg.supports_response = this->supports_response_;
+#ifdef USE_API_USER_DEFINED_ACTION_METADATA
+  msg.description = this->str_(1, scratch);
+#endif
+  msg.args.init(arg_types.size());
+  for (size_t i = 0; i < arg_types.size(); i++) {
+    size_t base = USER_ACTION_HEADER_STRINGS + i * USER_ACTION_ARG_STRINGS;
+    auto &arg = msg.args.emplace_back();
+    arg.type = arg_types[i];
+    arg.name = this->str_(base, scratch);
+#ifdef USE_API_USER_DEFINED_ACTION_METADATA
+    arg.description = this->str_(base + 1, scratch);
+    arg.example = this->str_(base + 2, scratch);
+#endif
+  }
+  return msg;
+}
+
 template<> bool get_execute_arg_value<bool>(const ExecuteServiceArgument &arg) { return arg.bool_; }
 template<> int32_t get_execute_arg_value<int32_t>(const ExecuteServiceArgument &arg) {
   if (arg.legacy_int != 0)

esphome/components/api/user_services.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <span>
 #include <tuple>
 #include <utility>
 #include <vector>
@@ -19,7 +20,9 @@ class APIServer;
 
 class UserServiceDescriptor {
  public:
-  virtual ListEntitiesServicesResponse encode_list_service_response() = 0;
+  /// Build the list-entities message. On ESP8266 the strings live in PROGMEM and are copied into
+  /// `scratch`, so the returned message is only valid while `scratch` is; other platforms ignore it.
+  virtual ListEntitiesServicesResponse encode_list_service_response(std::span<char> scratch) = 0;
 
   virtual bool execute_service(const ExecuteServiceRequest &req) = 0;
 #ifdef USE_API_USER_DEFINED_ACTION_RESPONSES
@@ -34,29 +37,51 @@ template<typename T> T get_execute_arg_value(const ExecuteServiceArgument &arg);
 
 template<typename T> enums::ServiceArgType to_service_arg_type();
 
-// Base class for YAML-defined services (most common case)
-// Stores only pointers to string literals in flash - no heap allocation
-template<typename... Ts> class UserServiceBase : public UserServiceDescriptor {
- public:
-  UserServiceBase(const char *name, const std::array<const char *, sizeof...(Ts)> &arg_names,
-                  enums::SupportsResponseType supports_response = enums::SUPPORTS_RESPONSE_NONE)
-      : name_(name), arg_names_(arg_names), supports_response_(supports_response) {
-    this->key_ = fnv1_hash(name);
-  }
+// Scratch buffer list-entities hands to encode_list_service_response(); only ESP8266 copies into it
+#ifdef USE_ESP8266
+using UserActionScratch = std::array<char, API_USER_ACTION_STRINGS_SCRATCH_SIZE>;
+#else
+using UserActionScratch = std::array<char, 0>;
+#endif
 
-  ListEntitiesServicesResponse encode_list_service_response() override {
-    ListEntitiesServicesResponse msg;
-    msg.name = StringRef(this->name_);
-    msg.key = this->key_;
-    msg.supports_response = this->supports_response_;
+// Non-template base for YAML-defined services so the list-entities encoder is compiled once.
+// All strings live in one PROGMEM pointer table emitted by codegen (see _action_strings in
+// __init__.py), so each service costs a single pointer of RAM. Layout: the action name, then
+// each argument name; with USE_API_USER_DEFINED_ACTION_METADATA the action description follows
+// the name and every argument is (name, description, example). Unset metadata is nullptr.
+#ifdef USE_API_USER_DEFINED_ACTION_METADATA
+static constexpr size_t USER_ACTION_HEADER_STRINGS = 2;
+static constexpr size_t USER_ACTION_ARG_STRINGS = 3;
+#else
+static constexpr size_t USER_ACTION_HEADER_STRINGS = 1;
+static constexpr size_t USER_ACTION_ARG_STRINGS = 1;
+#endif
+class UserServiceStatic : public UserServiceDescriptor {
+ public:
+  UserServiceStatic(const char *const *strings, uint32_t key,
+                    enums::SupportsResponseType supports_response = enums::SUPPORTS_RESPONSE_NONE)
+      : strings_(strings), key_(key), supports_response_(supports_response) {}
+
+ protected:
+  ListEntitiesServicesResponse encode_list_service_response_(std::span<const enums::ServiceArgType> arg_types,
+                                                             std::span<char> scratch) const;
+  /// Reference table entry `idx`; nullptr gives an empty StringRef.
+  /// On ESP8266 the bytes are copied out of PROGMEM into `scratch` with a terminator, and the span
+  /// is advanced past the copy.
+  StringRef str_(size_t idx, std::span<char> &scratch) const;
+
+  const char *const *strings_;  // PROGMEM pointer table, read with progmem_read_ptr()
+  uint32_t key_;
+  enums::SupportsResponseType supports_response_;
+};
+
+template<typename... Ts> class UserServiceBase : public UserServiceStatic {
+ public:
+  using UserServiceStatic::UserServiceStatic;
+
+  ListEntitiesServicesResponse encode_list_service_response(std::span<char> scratch) override {
     std::array<enums::ServiceArgType, sizeof...(Ts)> arg_types = {to_service_arg_type<Ts>()...};
-    msg.args.init(sizeof...(Ts));
-    for (size_t i = 0; i < sizeof...(Ts); i++) {
-      auto &arg = msg.args.emplace_back();
-      arg.type = arg_types[i];
-      arg.name = StringRef(this->arg_names_[i]);
-    }
-    return msg;
+    return this->encode_list_service_response_(arg_types, scratch);
   }
 
   bool execute_service(const ExecuteServiceRequest &req) override {
@@ -89,12 +114,6 @@ template<typename... Ts> class UserServiceBase : public UserServiceDescriptor {
   void execute_(const ArgsContainer &args, uint32_t call_id, bool return_response, std::index_sequence<S...> /*type*/) {
     this->execute(call_id, return_response, (get_execute_arg_value<Ts>(args[S]))...);
   }
-
-  // Pointers to string literals in flash - no heap allocation
-  const char *name_;
-  std::array<const char *, sizeof...(Ts)> arg_names_;
-  uint32_t key_{0};
-  enums::SupportsResponseType supports_response_{enums::SUPPORTS_RESPONSE_NONE};
 };
 
 // Separate class for custom_api_device services (rare case)
@@ -106,7 +125,7 @@ template<typename... Ts> class UserServiceDynamic : public UserServiceDescriptor
     this->key_ = fnv1_hash(this->name_.c_str());
   }
 
-  ListEntitiesServicesResponse encode_list_service_response() override {
+  ListEntitiesServicesResponse encode_list_service_response(std::span<char> /*scratch*/) override {
     ListEntitiesServicesResponse msg;
     msg.name = StringRef(this->name_);
     msg.key = this->key_;
@@ -167,8 +186,8 @@ template<typename... Ts>
 class UserServiceTrigger<enums::SUPPORTS_RESPONSE_NONE, Ts...> final : public UserServiceBase<Ts...>,
                                                                        public Trigger<Ts...> {
  public:
-  UserServiceTrigger(const char *name, const std::array<const char *, sizeof...(Ts)> &arg_names)
-      : UserServiceBase<Ts...>(name, arg_names, enums::SUPPORTS_RESPONSE_NONE) {}
+  UserServiceTrigger(const char *const *strings, uint32_t key)
+      : UserServiceBase<Ts...>(strings, key, enums::SUPPORTS_RESPONSE_NONE) {}
 
  protected:
   void execute(uint32_t /*call_id*/, bool /*return_response*/, Ts... x) override { this->trigger(x...); }
@@ -179,8 +198,8 @@ template<typename... Ts>
 class UserServiceTrigger<enums::SUPPORTS_RESPONSE_OPTIONAL, Ts...> final : public UserServiceBase<Ts...>,
                                                                            public Trigger<uint32_t, bool, Ts...> {
  public:
-  UserServiceTrigger(const char *name, const std::array<const char *, sizeof...(Ts)> &arg_names)
-      : UserServiceBase<Ts...>(name, arg_names, enums::SUPPORTS_RESPONSE_OPTIONAL) {}
+  UserServiceTrigger(const char *const *strings, uint32_t key)
+      : UserServiceBase<Ts...>(strings, key, enums::SUPPORTS_RESPONSE_OPTIONAL) {}
 
  protected:
   void execute(uint32_t call_id, bool return_response, Ts... x) override {
@@ -193,8 +212,8 @@ template<typename... Ts>
 class UserServiceTrigger<enums::SUPPORTS_RESPONSE_ONLY, Ts...> final : public UserServiceBase<Ts...>,
                                                                        public Trigger<uint32_t, Ts...> {
  public:
-  UserServiceTrigger(const char *name, const std::array<const char *, sizeof...(Ts)> &arg_names)
-      : UserServiceBase<Ts...>(name, arg_names, enums::SUPPORTS_RESPONSE_ONLY) {}
+  UserServiceTrigger(const char *const *strings, uint32_t key)
+      : UserServiceBase<Ts...>(strings, key, enums::SUPPORTS_RESPONSE_ONLY) {}
 
  protected:
   void execute(uint32_t call_id, bool /*return_response*/, Ts... x) override { this->trigger(call_id, x...); }
@@ -205,8 +224,8 @@ template<typename... Ts>
 class UserServiceTrigger<enums::SUPPORTS_RESPONSE_STATUS, Ts...> final : public UserServiceBase<Ts...>,
                                                                          public Trigger<uint32_t, Ts...> {
  public:
-  UserServiceTrigger(const char *name, const std::array<const char *, sizeof...(Ts)> &arg_names)
-      : UserServiceBase<Ts...>(name, arg_names, enums::SUPPORTS_RESPONSE_STATUS) {}
+  UserServiceTrigger(const char *const *strings, uint32_t key)
+      : UserServiceBase<Ts...>(strings, key, enums::SUPPORTS_RESPONSE_STATUS) {}
 
  protected:
   void execute(uint32_t call_id, bool /*return_response*/, Ts... x) override { this->trigger(call_id, x...); }