Merge remote-tracking branch 'origin/dev' into api-reverse-connection

# Conflicts: # tests/integration/test_light_initial_state.py
2026-09-09 14:28:46 +00:00 · 2026-09-08 18:13:24 +02:00 · 2026-09-08 18:11:39 +02:00 · 2026-09-08 18:10:45 +02:00 · 2026-09-05 13:07:37 +02:00 · 2026-09-05 11:23:59 +02:00
80 changed files with 2236 additions and 6414 deletions
@@ -1,39 +0,0 @@
-name: Cache Arduino ESP8266
-description: >
-  Resolve the pinned Arduino core and xtensa toolchain versions and cache the
-  native ESP8266 install (~110 MB framework + toolchain; no ccache store, the
-  seed job saves before any compile runs). Exports
-  ESPHOME_ARDUINO8266_PREFIX to the job so every later step installs into
-  the cached path; the Python venv must already be restored. Mirrors
-  cache-esp-idf: only dev-branch pushes write the shared cache, everything
-  else restores.
-runs:
-  using: composite
-  steps:
-    - name: Resolve the native toolchain cache key
-      # Versions are pinned in code, not a hashable file; resolve them so a
-      # bump changes the cache key. Assignment form so errexit catches a
-      # resolver failure.
-      id: version
-      shell: bash
-      run: |
-        # One owner for the install prefix: exported here and referenced by
-        # the cache steps below via env, so the caller's install and the
-        # cached path cannot diverge.
-        echo "ESPHOME_ARDUINO8266_PREFIX=$HOME/.esphome-arduino8266" >> "$GITHUB_ENV"
-        . venv/bin/activate
-        key=$(python -c 'from esphome.components.esp8266 import RECOMMENDED_ARDUINO_FRAMEWORK_VERSION as f; from esphome.arduino8266.framework import TOOLCHAIN_VERSION as t; print(f"{f}-{t}")')
-        [ -n "$key" ] || exit 1
-        echo "key=$key" >> "$GITHUB_OUTPUT"
-    - name: Cache the native toolchain (write on dev)
-      if: github.ref == 'refs/heads/dev'
-      uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
-      with:
-        path: ${{ env.ESPHOME_ARDUINO8266_PREFIX }}
-        key: ${{ runner.os }}-esp8266-native-${{ steps.version.outputs.key }}
-    - name: Restore the native toolchain (off dev)
-      if: github.ref != 'refs/heads/dev'
-      uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
-      with:
-        path: ${{ env.ESPHOME_ARDUINO8266_PREFIX }}
-        key: ${{ runner.os }}-esp8266-native-${{ steps.version.outputs.key }}
@@ -102,8 +102,6 @@ jobs:
      device-builder: ${{ steps.determine.outputs.device-builder }}
      esp32-platformio: ${{ steps.determine.outputs.esp32-platformio }}
      esp32-platformio-components: ${{ steps.determine.outputs.esp32-platformio-components }}
-      esp8266-native: ${{ steps.determine.outputs.esp8266-native }}
-      esp8266-native-components: ${{ steps.determine.outputs.esp8266-native-components }}
      changed-components: ${{ steps.determine.outputs.changed-components }}
      changed-components-with-tests: ${{ steps.determine.outputs.changed-components-with-tests }}
      directly-changed-components-with-tests: ${{ steps.determine.outputs.directly-changed-components-with-tests }}
@@ -167,8 +165,6 @@ jobs:
          echo "device-builder=$(echo "$output" | jq -r '.device_builder')" >> $GITHUB_OUTPUT
          echo "esp32-platformio=$(echo "$output" | jq -r '.esp32_platformio')" >> $GITHUB_OUTPUT
          echo "esp32-platformio-components=$(echo "$output" | jq -r '.esp32_platformio_components')" >> $GITHUB_OUTPUT
-          echo "esp8266-native=$(echo "$output" | jq -r '.esp8266_native')" >> $GITHUB_OUTPUT
-          echo "esp8266-native-components=$(echo "$output" | jq -r '.esp8266_native_components')" >> $GITHUB_OUTPUT
          echo "changed-components=$(echo "$output" | jq -c '.changed_components')" >> $GITHUB_OUTPUT
          echo "changed-components-with-tests=$(echo "$output" | jq -c '.changed_components_with_tests')" >> $GITHUB_OUTPUT
          echo "directly-changed-components-with-tests=$(echo "$output" | jq -c '.directly_changed_components_with_tests')" >> $GITHUB_OUTPUT
@@ -187,32 +183,6 @@ jobs:
          path: .temp/components_graph.json
          key: components-graph-${{ hashFiles('esphome/components/**/*.py') }}

-  seed-esp8266-native-cache:
-    name: Seed the esp8266 native toolchain cache
-    runs-on: ubuntu-24.04
-    needs:
-      - common
-    # PR-branch cache saves are invisible to other PRs, so dev pushes seed
-    # the shared entry test-esp8266-native restores. Only dev: the composite
-    # action saves nowhere else, so a beta/release push would download the
-    # toolchain and discard it.
-    if: github.event_name == 'push' && github.ref == 'refs/heads/dev'
-    timeout-minutes: 15
-    steps:
-      - name: Check out code from GitHub
-        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
-      - name: Restore Python
-        uses: ./.github/actions/restore-python
-        with:
-          python-version: ${{ env.DEFAULT_PYTHON }}
-          cache-key: ${{ needs.common.outputs.cache-key }}
-      - name: Cache the native toolchain
-        uses: ./.github/actions/cache-arduino8266
-      - name: Install the native toolchain
-        run: |
-          . venv/bin/activate
-          python -c "from esphome.arduino8266.framework import check_and_install; from esphome.components.esp8266 import RECOMMENDED_ARDUINO_FRAMEWORK_VERSION; check_and_install(RECOMMENDED_ARDUINO_FRAMEWORK_VERSION)"
-
  ci-custom:
    name: Run script/ci-custom
    runs-on: ubuntu-24.04
@@ -1267,7 +1237,7 @@ jobs:

          # compile validates config first, so a separate config pass is
          # redundant for this smoke test. ESP-IDF framework via PlatformIO:
-          python3 script/test_build_components.py -e compile -t esp32-idf -c "$TEST_COMPONENTS" -f --toolchain platformio --fail-on-no-tests
+          python3 script/test_build_components.py -e compile -t esp32-idf -c "$TEST_COMPONENTS" -f --toolchain platformio

          echo ""
          echo "ESP-IDF-via-PlatformIO build passed! Starting Arduino smoke test..."
@@ -1276,40 +1246,6 @@ jobs:
          # Arduino framework via PlatformIO (only components with an esp32-ard test are built):
          python3 script/test_build_components.py -e compile -t esp32-ard -c "$TEST_COMPONENTS" -f --toolchain platformio

-  test-esp8266-native:
-    name: Test esp8266 components with the native toolchain
-    runs-on: ubuntu-24.04
-    needs:
-      - common
-      - determine-jobs
-    if: github.event_name == 'pull_request' && needs.determine-jobs.outputs.esp8266-native == 'true'
-    env:
-      # Computed by script/determine-jobs.py (ESP8266_NATIVE_TEST_COMPONENTS)
-      TEST_COMPONENTS: ${{ needs.determine-jobs.outputs.esp8266-native-components }}
-    steps:
-      - name: Check out code from GitHub
-        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
-
-      - name: Restore Python
-        uses: ./.github/actions/restore-python
-        with:
-          python-version: ${{ env.DEFAULT_PYTHON }}
-          cache-key: ${{ needs.common.outputs.cache-key }}
-
-      - name: Cache the native toolchain
-        uses: ./.github/actions/cache-arduino8266
-
-      - name: Run native toolchain compile test
-        run: |
-          . venv/bin/activate
-
-          echo "Testing components: $TEST_COMPONENTS"
-          echo ""
-
-          # ESP8266 Arduino built directly (no PlatformIO); compile validates
-          # config first, so a separate config pass is redundant.
-          python3 script/test_build_components.py -e compile -t esp8266-ard -c "$TEST_COMPONENTS" -f --toolchain arduino --fail-on-no-tests
-
  device-builder:
    name: Test downstream esphome/device-builder
    runs-on: ubuntu-24.04
@@ -1672,7 +1608,6 @@ jobs:
    needs:
      - common
      - seed-apt-cache
-      - seed-esp8266-native-cache
      - determine-jobs
      - ci-custom
      - pylint
@@ -1688,7 +1623,6 @@ jobs:
      - clang-tidy-esp32-variants
      - test-build-components-split
      - test-esp32-platformio
-      - test-esp8266-native
      - device-builder
      - memory-impact-target-branch
      - memory-impact-pr-branch
@@ -817,9 +817,7 @@ def write_cpp_file() -> int:
        from esphome.build_gen import espidf

        espidf.write_project()
-    elif not CORE.using_native_toolchain:
-        # Other native builds generate their project at compile time;
-        # never write a platformio.ini for them
+    else:
        from esphome.build_gen import platformio

        platformio.write_project()
@@ -861,14 +859,20 @@ def compile_program(args: ArgsProtocol, config: ConfigType) -> int:
        toolchain.create_factory_bin()
        toolchain.create_ota_bin()
        toolchain.create_elf_copy()
-        from esphome.build_helpers.idedata import warn_if_idedata_missing
+        from esphome.build_helpers.idedata import IDEDATA_BEST_EFFORT_ERRORS

-        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"
-        )
+        try:
+            if toolchain.get_idedata() is None:
+                _LOGGER.warning("No idedata was generated for this build")
+        except IDEDATA_BEST_EFFORT_ERRORS as err:
+            # The firmware already built; an idedata failure must not fail
+            # a successful build.
+            _LOGGER.warning(
+                "Could not generate idedata: %s (IDE, clang-tidy, and "
+                "memory-analysis data will be unavailable for this build)",
+                err,
+            )
+            _LOGGER.debug("Idedata failure detail", exc_info=True)
    else:
        from esphome.platformio import toolchain

@@ -971,15 +975,12 @@ def upload_using_esptool(

    if file is not None:
        flash_images = [FlashImage(path=file, offset="0x0")]
-    elif (native := _native_toolchain_module()) 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")]
+    elif CORE.using_toolchain_esp_idf:
+        from esphome.espidf import toolchain
+
+        flash_images = [
+            FlashImage(path=toolchain.get_factory_firmware_path(), offset="0x0")
+        ]
    else:
        from esphome.platformio import toolchain

@@ -1961,39 +1962,15 @@ def command_update_all(args: ArgsProtocol) -> int | None:
    return run_multiple_configs(files, build_command)


-# Native build backend per (target platform, toolchain). Keyed here rather
-# than through a platform hook so the serial upload/logs fast path never
-# imports the platform component package (see the esp32 variant comment in
-# upload_using_esptool); the platform half comes from CORE.data the same way.
-_NATIVE_TOOLCHAIN_MODULES = {
-    ("esp32", Toolchain.ESP_IDF): "esphome.espidf.toolchain",
-    ("esp8266", Toolchain.ARDUINO): "esphome.arduino8266.toolchain",
-}
-
-
-def _native_toolchain_module():
-    """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)
-
-
 def command_idedata(args: ArgsProtocol, config: ConfigType) -> int:
    import json

-    native_toolchain = _native_toolchain_module()
+    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

-    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()
+        idedata = espidf_toolchain.get_idedata()
        if idedata is None:
            _LOGGER.error(
                "No idedata available; compile the configuration first",
@@ -2032,17 +2009,6 @@ 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
-    native_toolchain = _native_toolchain_module()
-    if native_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:
@@ -2054,31 +2020,13 @@ def command_analyze_memory(args: ArgsProtocol, config: ConfigType) -> int:

    # Get idedata for analysis
    idedata = None
-    if native_toolchain is not None:
-        objdump = native_toolchain.get_objdump_path()
-        readelf = native_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. clean-all is heavy for
-                # ESP-IDF, so suggest a recompile first.
-                _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)
+    if CORE.using_toolchain_esp_idf:
+        from esphome.espidf import toolchain

-        firmware_elf = native_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
+        objdump_path = str(toolchain.get_objdump_path())
+        readelf_path = str(toolchain.get_readelf_path())
+
+        firmware_elf = toolchain.get_elf_path()
    else:
        from esphome.platformio import toolchain

@@ -1,329 +0,0 @@
-"""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 Any
-
-from esphome.arduino8266 import framework
-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_if_changed
-from esphome.types import ConfigType
-
-_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.
-
-    The consumed set is exported by core/config.py next to the routing that
-    stores these options, so the two cannot drift; YAML upload_speed never
-    reaches CORE.platformio_options here.
-    """
-    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:
-    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.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 per build: the resolution probes PATH and spawns the
-    # runnability check, and three consumers need the same answer
-    ccache = resolve_ccache_path()
-    ninja_changed = build_gen.write_project(paths, ccache)
-
-    build_dir = get_build_dir()
-    env = framework.get_build_env(paths.toolchain, ccache)
-
-    # Regenerate the compile DB before the build (a pure function of
-    # build.ninja); skip only when it is at least as fresh as build.ninja
-    # (an interrupted previous run may have rewritten the manifest without
-    # regenerating the DB).
-    compdb = build_dir / "compile_commands.json"
-    compdb_stamp = build_dir / ".compile_commands.stamp"
-    ninja_file = build_dir / "build.ninja"
-    # Freshness rides a stamp: the DB itself is written through
-    # write_file_if_changed (its mtime feeds get_idedata's cache), so a
-    # regeneration with identical content would stay "stale" forever
-    if (
-        ninja_changed
-        or not compdb.is_file()
-        or not compdb_stamp.is_file()
-        or compdb_stamp.stat().st_mtime < ninja_file.stat().st_mtime
-    ):
-        _write_compile_commands(paths.ninja, build_dir, env)
-        compdb_stamp.touch()
-
-    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, not the default statement: a generator defect that
-    # drops them fails loudly with "unknown target" instead of a green
-    # no-op run that leaves stale artifacts in place
-    targets = ["firmware.factory.bin", "firmware.ota.bin"]
-    cmd += targets
-
-    # A dry-run probe keeps a no-op rebuild quiet: ninja would only print
-    # "no work to do". A freshly rewritten manifest all but guarantees work,
-    # so skip the probe (and its full stat pass) on that path. cwd instead
-    # of -C also drops the "Entering directory" banner on real builds.
-    skip_build = False
-    if not ninja_changed:
-        probe = subprocess.run(
-            [str(paths.ninja), "-n", *targets],
-            cwd=build_dir,
-            env=env,
-            capture_output=True,
-            text=True,
-            check=False,
-            close_fds=False,
-        )
-        if probe.stderr.strip():
-            # A load-time diagnostic (e.g. "multiple rules generate X")
-            # flags a generator bug; the skip branch would otherwise
-            # swallow it forever
-            _LOGGER.warning("ninja: %s", probe.stderr.strip())
-        if probe.returncode != 0:
-            # An unknown target here is the defective-manifest case; fall
-            # through to the real build so the error prints attributably
-            _LOGGER.debug("ninja probe failed; running the full build")
-        skip_build = probe.returncode == 0 and "no work to do" in probe.stdout
-    if skip_build:
-        _LOGGER.debug("ninja: nothing to rebuild")
-    else:
-        _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 a manifest missing the explicit targets above;
-    # existence covers the remaining hole (a rule that ran but wrote
-    # elsewhere). The factory/ota copies are what upload and OTA consume.
-    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):
-        # The cause was already warned; name the consequence so a build
-        # contributing no RAM/Flash metric is visible to 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_if_changed keeps the mtime stable on no-op builds so the
-    # idedata cache in get_idedata() stays valid.
-    write_file_if_changed(compdb, result.stdout)
-
-
-def _parse_app_size(build_dir: Path, paths: framework.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:
-        # UnicodeDecodeError: a truncated/corrupt script must degrade to
-        # the same warning, never abort an already-linked build
-        _LOGGER.warning("Cannot read linker script for the Flash summary: %s", err)
-        return None
-    app_size = segment_length(ld_text, "irom0_0_seg")
-    if app_size is None:
-        _LOGGER.warning("irom0_0_seg not found in %s; skipping Flash summary", ld_path)
-        return None
-    if app_size == 0:
-        _LOGGER.warning(
-            "irom0_0_seg has zero length in %s; skipping Flash summary", ld_path
-        )
-        return None
-    return app_size
-
-
-def _print_size_summary(build_dir: Path, paths: framework.InstalledPaths) -> bool:
-    """Print the PlatformIO-shaped RAM/Flash lines; False when skipped.
-
-    The exact shape (including the bar) is parsed by
-    ``script/ci_memory_impact_extract.py``; ``print_size_line`` matches it.
-    """
-    from esphome.build_helpers.size_summary import print_size_line
-
-    size_tool = _toolchain_tool("size")
-    try:
-        result = subprocess.run(
-            [str(size_tool), "-A", "-d", str(get_elf_path())],
-            capture_output=True,
-            text=True,
-            check=False,
-            close_fds=False,
-        )
-    except OSError 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
-    if result.returncode != 0:
-        _LOGGER.warning("Could not summarize firmware size: %s", result.stderr)
-        return False
-    sections: dict[str, int] = {}
-    for line in result.stdout.splitlines():
-        parts = line.split()
-        if len(parts) >= 2 and parts[0].startswith("."):
-            try:
-                sections[parts[0]] = int(parts[1])
-            except ValueError:
-                # An unparsed RAM/Flash section trips the missing-sections
-                # guard below, so no total is built on a dropped value
-                _LOGGER.warning("Unparsable size output for section %s", parts[0])
-    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 anything: a RAM line without
-    # its Flash line would let CI's memory-impact extraction sum the two
-    # metrics over different build counts (_parse_app_size already warned).
-    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
-
-
-# Sentinel: "resolve for me"; None is a real value meaning disabled.
-_CCACHE_UNRESOLVED: Any = object()
-
-
-def get_idedata(ccache: str | None = _CCACHE_UNRESOLVED) -> dict | None:
-    """Derive idedata from the build's compile_commands.json.
-
-    Same contract as ``espidf.toolchain.get_idedata``: the fields IDE
-    integrations, clang-tidy, and the memory analyzer expect.
-    """
-    from esphome.build_helpers.idedata import load_or_build_idedata
-
-    if ccache is _CCACHE_UNRESOLVED:
-        # Deliberately uncached: env/PATH can change between builds in a
-        # long-lived host process
-        ccache = 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(ccache) if ccache else None,
-    )
@@ -11,7 +11,6 @@ consumers (IDE integration, clang-tidy) expect:

 from __future__ import annotations

-from collections.abc import Callable
 import json
 import logging
 import os
@@ -22,8 +21,6 @@ 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 = (
@@ -34,30 +31,7 @@ IDEDATA_BEST_EFFORT_ERRORS = (
    ValueError,
 )

-
-def warn_if_idedata_missing(get_idedata: Callable[[], dict | None]) -> None:
-    """Run an idedata generator, downgrading any failure to a warning.
-
-    Shared by the native backends: the firmware already built, so a missing
-    or broken idedata must not fail a successful build.
-    """
-    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,
-        )
-        if isinstance(err, (EsphomeError, OSError)):
-            # Routine environmental failures keep the detail at debug
-            _LOGGER.debug("Idedata failure detail", exc_info=True)
-        else:
-            # LookupError/ValueError/RuntimeError smell like a parsing bug;
-            # a permanently masked traceback would hide it on every build
-            _LOGGER.warning("Idedata failure detail", exc_info=True)
-
+_LOGGER = logging.getLogger(__name__)

 # C++ translation-unit suffixes used to identify ESPHome source files.
 _CXX_SUFFIXES = (".cpp", ".cc")
@@ -5,7 +5,7 @@ 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.const import CONF_DESCRIPTION, CONF_HOST
 from esphome.components.logger import request_log_listener

 # ENCRYPTION_SCHEMA and validate_encryption_key are re-exported for external
@@ -25,6 +25,8 @@ from esphome.const import (
    CONF_CAPTURE_RESPONSE,
    CONF_DATA,
    CONF_DATA_TEMPLATE,
+    CONF_DELAY,
+    CONF_ENABLE_IPV6,
    CONF_ENCRYPTION,
    CONF_EVENT,
    CONF_ID,
@@ -48,6 +50,7 @@ from esphome.const import (
 )
 from esphome.core import CORE, ID, CoroPriority, EsphomeError, coroutine_with_priority
 from esphome.cpp_generator import MockObj, TemplateArgsType
+import esphome.final_validate as fv
 from esphome.helpers import fnv1_hash
 from esphome.types import ConfigFragmentType, ConfigType

@@ -134,6 +137,7 @@ CONF_HOMEASSISTANT_SERVICES = "homeassistant_services"
 CONF_HOMEASSISTANT_STATES = "homeassistant_states"
 CONF_LISTEN_BACKLOG = "listen_backlog"
 CONF_MAX_SEND_QUEUE = "max_send_queue"
+CONF_OUTGOING_CONNECTION = "outgoing_connection"
 CONF_STATE_SUBSCRIPTION_ONLY = "state_subscription_only"


@@ -285,9 +289,44 @@ def _consume_api_sockets(config: ConfigType) -> ConfigType:
    # (not max_connections, which is the upper limit rarely reached)
    socket.consume_sockets(3, "api")(config)
    socket.consume_sockets(1, "api", socket.SocketType.TCP_LISTEN)(config)
+    if CONF_OUTGOING_CONNECTION in config:
+        socket.consume_sockets(1, "api_outgoing_connection")(config)
    return config


+def _validate_outgoing_connection(config: ConfigType) -> ConfigType:
+    if CONF_OUTGOING_CONNECTION not in config:
+        return config
+    if CONF_ENCRYPTION not in config:
+        raise cv.Invalid(
+            "outgoing_connection requires 'encryption' so the peer is verified by key",
+            path=[CONF_OUTGOING_CONNECTION],
+        )
+    return config
+
+
+_OUTGOING_CONNECTION_SCHEMA = cv.Schema(
+    {
+        cv.Optional(CONF_HOST): cv.ipaddress,
+        cv.Optional(CONF_PORT, default=6054): cv.port,
+        # Bounded to half the device's uint32 millisecond range so the wait
+        # always elapses under a wrapping clock
+        cv.Optional(CONF_DELAY, default="60s"): cv.All(
+            cv.positive_time_period_milliseconds,
+            cv.Range(max=cv.TimePeriod(milliseconds=2147483647)),
+        ),
+    }
+)
+
+
+def _outgoing_connection_schema(config: ConfigType | None) -> ConfigType:
+    # A bare `outgoing_connection:` block is valid; without a host the device
+    # dials the remembered last dial-back client
+    if config is None:
+        config = {}
+    return _OUTGOING_CONNECTION_SCHEMA(config)
+
+
 CONFIG_SCHEMA = cv.All(
    cv.Schema(
        {
@@ -312,6 +351,7 @@ CONFIG_SCHEMA = cv.All(
            ): ACTIONS_SCHEMA,
            cv.Exclusive(CONF_ACTIONS, group_of_exclusion=CONF_ACTIONS): ACTIONS_SCHEMA,
            cv.Optional(CONF_ENCRYPTION): encryption_schema,
+            cv.Optional(CONF_OUTGOING_CONNECTION): _outgoing_connection_schema,
            cv.Optional(CONF_BATCH_DELAY, default="100ms"): cv.All(
                cv.positive_time_period_milliseconds,
                cv.Range(max=cv.TimePeriod(milliseconds=65535)),
@@ -368,6 +408,7 @@ CONFIG_SCHEMA = cv.All(
        }
    ).extend(cv.COMPONENT_SCHEMA),
    cv.rename_key(CONF_SERVICES, CONF_ACTIONS),
+    _validate_outgoing_connection,
    _consume_api_sockets,
    _register_provisioning_source,
 )
@@ -424,7 +465,52 @@ def _validate_esp8266_action_strings(config: ConfigType) -> ConfigType:
    return config


-FINAL_VALIDATE_SCHEMA = _validate_esp8266_action_strings
+def _validate_outgoing_socket_implementation(config: ConfigType) -> ConfigType:
+    """Reject the raw lwip_tcp socket, the only option on ESP8266 and RP2040.
+
+    Checked against the resolved implementation so an explicit selection on
+    another platform is caught the same way as the platform default.
+    """
+    if CONF_OUTGOING_CONNECTION not in config:
+        return config
+    from esphome.components import socket
+
+    socket_conf = fv.full_config.get().get("socket") or {}
+    if (
+        impl := socket_conf.get(socket.CONF_IMPLEMENTATION)
+    ) in socket.IMPLEMENTATIONS_WITHOUT_CONNECT:
+        raise cv.Invalid(
+            f"outgoing_connection is not supported with the {impl} socket "
+            "implementation (the only one on ESP8266 and RP2040) because it "
+            "cannot make outgoing connections",
+            path=[CONF_OUTGOING_CONNECTION],
+        )
+    return config
+
+
+def _validate_outgoing_host_ipv6(config: ConfigType) -> ConfigType:
+    """An IPv6 host can never be parsed, so never dialed, without IPv6."""
+    if (
+        (outgoing := config.get(CONF_OUTGOING_CONNECTION)) is None
+        or (host := outgoing.get(CONF_HOST)) is None
+        or host.version != 6
+    ):
+        return config
+    network_conf = fv.full_config.get().get("network") or {}
+    if not network_conf.get(CONF_ENABLE_IPV6):
+        raise cv.Invalid(
+            "outgoing_connection host is an IPv6 address but IPv6 is not "
+            "enabled; set 'network: enable_ipv6: true'",
+            path=[CONF_OUTGOING_CONNECTION, CONF_HOST],
+        )
+    return config
+
+
+FINAL_VALIDATE_SCHEMA = cv.All(
+    _validate_esp8266_action_strings,
+    _validate_outgoing_socket_implementation,
+    _validate_outgoing_host_ipv6,
+)


 def _add_action_strings(
@@ -606,6 +692,13 @@ async def to_code(config: ConfigType) -> None:
    else:
        cg.add_define("USE_API_PLAINTEXT")

+    if (outgoing := config.get(CONF_OUTGOING_CONNECTION)) is not None:
+        cg.add_define("USE_API_OUTGOING_CONNECTION")
+        if (host := outgoing.get(CONF_HOST)) is not None:
+            cg.add_define("API_OUTGOING_CONNECTION_HOST", str(host))
+        cg.add_define("API_OUTGOING_CONNECTION_PORT", outgoing[CONF_PORT])
+        cg.add_define("API_OUTGOING_CONNECTION_DELAY", outgoing[CONF_DELAY])
+
    cg.add_define("USE_API")
    cg.add_global(api_ns.using)

@@ -992,6 +1085,7 @@ _define_filter = filter_source_files_from_defines(
        "user_services.cpp": "USE_API_USER_DEFINED_ACTIONS",
        "api_frame_helper_noise.cpp": "USE_API_NOISE",
        "api_frame_helper_plaintext.cpp": "USE_API_PLAINTEXT",
+        "api_outgoing_connection.cpp": "USE_API_OUTGOING_CONNECTION",
    }
 )

@@ -112,6 +112,11 @@ message HelloRequest {
  string client_info = 1;
  uint32 api_version_major = 2;
  uint32 api_version_minor = 3;
+
+  // Set by clients that can accept connections the device opens to them
+  // (see api: outgoing_connection:). The device remembers this client's
+  // address as the target to dial when no such client is connected.
+  bool outgoing_connection_target = 4 [(field_ifdef) = "USE_API_OUTGOING_CONNECTION"];
 }

 // Confirmation of successful connection request.
@@ -331,6 +336,10 @@ message DeviceInfoResponse {
  // all-zeros PSK, so the api encryption key can be provisioned without being
  // sent in plaintext (protects against passive sniffing, not active MITM)
  bool api_encryption_provisionable = 26 [(field_ifdef) = "USE_API_NOISE"];
+
+  // Device is built with the api outgoing_connection option and can open
+  // the TCP connection to a dial-back target itself
+  bool api_outgoing_connection_supported = 27 [(field_ifdef) = "USE_API_OUTGOING_CONNECTION"];
 }

 // ==================== DEVICE CAPABILITIES ====================
@@ -1822,6 +1822,19 @@ bool APIConnection::send_hello_response_(const HelloRequest &msg) {
  // Auto-authenticate - password auth was removed in ESPHome 2026.1.0
  this->complete_authentication_();

+#ifdef USE_API_OUTGOING_CONNECTION
+  // With a PSK set only key-verified transports reach hello: plaintext and
+  // zero-PSK are rejected, and pre-activation sessions are force-closed
+  if (msg.outgoing_connection_target && !this->flags_.outgoing_connection_target) {
+    if (this->parent_->get_noise_ctx().has_psk()) {
+      this->flags_.outgoing_connection_target = true;
+      this->parent_->on_outgoing_target_client(this);
+    } else {
+      this->log_client_(ESPHOME_LOG_LEVEL_WARN, LOG_STR("Dial-back target refused; no key active"));
+    }
+  }
+#endif
+
  return this->send_message(resp);
 }

@@ -1944,6 +1957,9 @@ bool APIConnection::send_device_info_response_() {
  // one) so this advertisement survives the plaintext removal in 2027.2.0.
  resp.api_encryption_provisionable = !this->parent_->get_noise_ctx().has_psk();
 #endif
+#ifdef USE_API_OUTGOING_CONNECTION
+  resp.api_outgoing_connection_supported = true;
+#endif
 #endif
 #ifdef USE_DEVICES
  size_t device_index = 0;
@@ -375,6 +375,21 @@ class APIConnection final : public APIServerConnectionBase {
    return this->helper_->get_peername_to(buf);
  }

+#ifdef USE_API_OUTGOING_CONNECTION
+  /// Outgoing connection: send our server hello immediately so the peer can
+  /// pick the matching key. Outgoing connections are only dialed when a PSK
+  /// is set, so the helper is always the noise helper. Call after start().
+  void mark_outgoing() {
+    if (this->flags_.remove) {
+      return;  // start() failed; the connection is already being torn down
+    }
+    APIError err = static_cast<APINoiseFrameHelper *>(this->helper_.get())->send_server_hello_first();
+    if (err != APIError::OK) {
+      this->fatal_error_with_log_(LOG_STR("Server hello failed"), err);
+    }
+  }
+#endif
+
 protected:
  bool try_to_clear_buffer_slow_(bool log_out_of_space);

@@ -745,6 +760,9 @@ class APIConnection final : public APIServerConnectionBase {
    uint8_t batch_first_message : 1;          // For batch buffer allocation
    uint8_t should_try_send_immediately : 1;  // True after initial states are sent
    uint8_t may_have_remaining_data : 1;      // Read loop hit limit, retry without ready check
+#ifdef USE_API_OUTGOING_CONNECTION
+    uint8_t outgoing_connection_target : 1;  // Client declared itself a dial-back target in its hello
+#endif
 #ifdef HAS_PROTO_MESSAGE_DUMP
    uint8_t log_only_mode : 1;
 #endif
@@ -282,7 +282,8 @@ class APIFrameHelper {
    DATA = 5,
    CLOSED = 6,
    FAILED = 7,
-    EXPLICIT_REJECT = 8,  // Noise only
+    EXPLICIT_REJECT = 8,        // Noise only
+    CLIENT_HELLO_OUTGOING = 9,  // Noise only: like CLIENT_HELLO but the server hello already went out (outgoing conn)
  };

  // Fast inline state check for read_packet/write_protobuf_messages hot path.
@@ -81,6 +81,13 @@ APIError APINoiseFrameHelper::init() {
  state_ = State::CLIENT_HELLO;
  return APIError::OK;
 }
+#ifdef USE_API_OUTGOING_CONNECTION
+APIError APINoiseFrameHelper::send_server_hello_first() {
+  // The peer needs our name and MAC to pick the key before its first message
+  this->state_ = State::CLIENT_HELLO_OUTGOING;
+  return this->send_server_hello_frame_();
+}
+#endif
 #ifdef USE_API_PLAINTEXT
 APIError APINoiseFrameHelper::init_from_handoff(const uint8_t *header, uint8_t header_len) {
  APIError err = this->init();
@@ -253,6 +260,9 @@ APIError APINoiseFrameHelper::state_action_() {
      HELPER_LOG("Bad state for method: %d", (int) this->state_);
      return APIError::BAD_STATE;
    case State::CLIENT_HELLO:
+#ifdef USE_API_OUTGOING_CONNECTION
+    case State::CLIENT_HELLO_OUTGOING:
+#endif
      return this->state_action_client_hello_();
    case State::SERVER_HELLO:
      return this->state_action_server_hello_();
@@ -285,11 +295,16 @@ APIError APINoiseFrameHelper::state_action_client_hello_() {
    std::memcpy(this->prologue_.data() + old_size + 2, this->rx_buf_.data(), rx_size);
  }

+#ifdef USE_API_OUTGOING_CONNECTION
+  if (this->state_ == State::CLIENT_HELLO_OUTGOING) {
+    // Server hello already went out at handoff
+    return this->start_handshake_();
+  }
+#endif
  state_ = State::SERVER_HELLO;
  return APIError::OK;
 }
-APIError APINoiseFrameHelper::state_action_server_hello_() {
-  // send server hello
+APIError APINoiseFrameHelper::send_server_hello_frame_() {
  const auto &name = App.get_name();
  char mac[MAC_ADDRESS_BUFFER_SIZE];
  get_mac_address_into_buffer(mac);
@@ -313,15 +328,18 @@ APIError APINoiseFrameHelper::state_action_server_hello_() {
  // node mac, terminated by null byte
  std::memcpy(msg + mac_offset, mac, MAC_ADDRESS_BUFFER_SIZE);

-  APIError aerr = write_frame_(msg, total_size);
+  return write_frame_(msg, total_size);
+}
+APIError APINoiseFrameHelper::state_action_server_hello_() {
+  APIError aerr = this->send_server_hello_frame_();
  if (aerr != APIError::OK)
    return aerr;
-
-  // start handshake
-  aerr = init_handshake_();
+  return this->start_handshake_();
+}
+APIError APINoiseFrameHelper::start_handshake_() {
+  APIError aerr = init_handshake_();
  if (aerr != APIError::OK)
    return aerr;
-
  state_ = State::HANDSHAKE;
  return APIError::OK;
 }
@@ -28,6 +28,12 @@ class APINoiseFrameHelper final : public APIFrameHelper {
  // Seeds the already-read header bytes and pumps the handshake state machine
  // until it would block.
  APIError init_from_handoff(const uint8_t *header, uint8_t header_len);
+#endif
+#ifdef USE_API_OUTGOING_CONNECTION
+  // Send the server hello immediately so the peer can pick the key before
+  // its PSK-mixed message. Call after init(); the mode is tracked in state_
+  // so the helper does not grow.
+  APIError send_server_hello_first();
 #endif
  APIError loop() override;
  APIError read_packet(ReadPacketBuffer *buffer) override;
@@ -39,6 +45,8 @@ class APINoiseFrameHelper final : public APIFrameHelper {
  APIError state_action_();
  APIError state_action_client_hello_();
  APIError state_action_server_hello_();
+  APIError send_server_hello_frame_();
+  APIError start_handshake_();
  APIError state_action_handshake_();
  APIError state_action_handshake_read_();
  APIError state_action_handshake_write_();
@@ -0,0 +1,236 @@
+#include "api_outgoing_connection.h"
+#if defined(USE_API) && defined(USE_API_OUTGOING_CONNECTION)
+
+#include "api_connection.h"
+#include "api_server.h"
+#include "esphome/components/network/util.h"
+#include "esphome/core/application.h"
+#include "esphome/core/helpers.h"
+#include "esphome/core/log.h"
+
+#include <cerrno>
+#include <cinttypes>
+#include <cstring>
+
+namespace esphome::api {
+
+static const char *const TAG = "api.outgoing";
+
+void OutgoingConnectionManager::setup() {
+#ifndef API_OUTGOING_CONNECTION_HOST
+  this->target_pref_ = global_preferences->make_preference<SavedOutgoingTarget>(629847102UL, true);
+  if (this->target_pref_.load(&this->saved_)) {
+    // Defend against a corrupt or truncated blob before the first read
+    this->saved_.host[sizeof(this->saved_.host) - 1] = '\0';
+    this->host_persisted_ = true;
+    ESP_LOGD(TAG, "Loaded target %s", this->saved_.host);
+  } else {
+    // Never saved, or the blob failed its size/CRC check
+    ESP_LOGD(TAG, "No saved target");
+    this->saved_ = {};
+  }
+#endif
+}
+
+void OutgoingConnectionManager::loop(APIServer *server) {
+  if (server->has_outgoing_target_client_()) {
+    return;  // on_target_client() already reset the dial state
+  }
+  if (this->dialed_conn_ != nullptr) {
+    // A live dialed session (flagged or not, e.g. a host: peer) is the
+    // target; a silent one dies on the handshake timeout
+    return;
+  }
+  const uint32_t now = App.get_loop_component_start_time();
+  switch (this->state_) {
+    case DialState::DIAL_STATE_IDLE:
+#ifdef USE_DEEP_SLEEP
+      // A deep sleep wake window is too short to spend on the delay
+      this->schedule_wait_(now, BACKOFF_MIN_MS);
+#else
+      // Target went away; give it the configured delay to reconnect first
+      this->schedule_wait_(now, API_OUTGOING_CONNECTION_DELAY);
+#endif
+      break;
+    case DialState::DIAL_STATE_WAITING:
+      if (now - this->state_ts_ >= this->wait_) {
+        this->try_dial_(server, now);
+      }
+      break;
+    case DialState::DIAL_STATE_CONNECTING:
+      this->poll_connect_(server, now);
+      break;
+  }
+}
+
+void OutgoingConnectionManager::try_dial_(APIServer *server, uint32_t now) {
+  if (!network::is_connected()) {
+    // Flips within seconds of boot; recheck fast so a deep sleep wake
+    // window is not spent waiting
+    this->schedule_wait_(now, NETWORK_RETRY_MS);
+    return;
+  }
+  const char *host = this->target_host_();
+  if (host == nullptr) {
+    // The steady state until a dial-back client has ever connected
+    ESP_LOGV(TAG, "Not dialing: no target");
+    this->schedule_wait_(now, PRECONDITION_RETRY_MS);
+    return;
+  }
+  const bool at_limit = server->at_client_limit_();
+  if (at_limit || !server->noise_ctx_.has_psk()) {
+    ESP_LOGD(TAG, "Not dialing: %s", at_limit ? "max connections" : "no key");
+    // Not a dial failure; retry without escalating the backoff
+    this->schedule_wait_(now, PRECONDITION_RETRY_MS);
+    return;
+  }
+  struct sockaddr_storage addr;
+  socklen_t addr_len =
+      socket::set_sockaddr((struct sockaddr *) &addr, sizeof(addr), host, API_OUTGOING_CONNECTION_PORT);
+  if (addr_len == 0) {
+    ESP_LOGW(TAG, "Invalid target %s", host);
+#ifndef API_OUTGOING_CONNECTION_HOST
+    // A corrupt remembered value can never become dialable; forget it
+    // (covers an IPv6 literal left by an earlier enable_ipv6 build too)
+    this->saved_ = {};
+    if (!this->persist_target_()) {
+      ESP_LOGW(TAG, "Failed to clear target");
+    }
+#endif
+    this->schedule_retry_(now);
+    return;
+  }
+  this->dial_socket_ = socket::socket_loop_monitored(((struct sockaddr *) &addr)->sa_family, SOCK_STREAM, IPPROTO_TCP);
+  if (!this->dial_socket_ || this->dial_socket_->setblocking(false) != 0) {
+    ESP_LOGW(TAG, "Socket %s failed: errno %d", this->dial_socket_ ? "setblocking" : "create", errno);
+    this->schedule_retry_(now);
+    return;
+  }
+  ESP_LOGD(TAG, "Dialing %s:%u", host, API_OUTGOING_CONNECTION_PORT);
+  int err = this->dial_socket_->connect((struct sockaddr *) &addr, addr_len);
+  if (err == 0) {
+    // Immediate success (possible for localhost)
+    this->handoff_(server, now);
+    return;
+  }
+  if (errno != EINPROGRESS) {
+    ESP_LOGW(TAG, "Connect failed: errno %d", errno);
+    this->schedule_retry_(now);
+    return;
+  }
+  this->state_ = DialState::DIAL_STATE_CONNECTING;
+  this->state_ts_ = now;
+  this->last_poll_ = now;
+}
+
+void OutgoingConnectionManager::poll_connect_(APIServer *server, uint32_t now) {
+  if (now - this->state_ts_ >= CONNECT_TIMEOUT_MS) {
+    ESP_LOGW(TAG, "Connect timeout");
+    this->schedule_retry_(now);
+    return;
+  }
+  if (now - this->last_poll_ < CONNECT_POLL_INTERVAL_MS) {
+    return;
+  }
+  this->last_poll_ = now;
+  int err = 0;
+  switch (socket::poll_connect(*this->dial_socket_, err)) {
+    case socket::ConnectPollResult::CONNECT_POLL_PENDING:
+      break;
+    case socket::ConnectPollResult::CONNECT_POLL_CONNECTED:
+      this->handoff_(server, now);
+      break;
+    case socket::ConnectPollResult::CONNECT_POLL_ERROR:
+      ESP_LOGW(TAG, "Connect failed: %d", err);
+      this->schedule_retry_(now);
+      break;
+  }
+}
+
+void OutgoingConnectionManager::handoff_(APIServer *server, uint32_t now) {
+  this->dialed_conn_ = server->add_outgoing_client_(std::move(this->dial_socket_));
+  if (this->dialed_conn_ == nullptr) {
+    // Only preconditions (slot limit, key cleared) refuse the handoff; the
+    // peer is reachable, so do not escalate the backoff
+    this->schedule_wait_(now, PRECONDITION_RETRY_MS);
+    return;
+  }
+  // Connected; dialed_conn_ gates further dialing until the session settles
+  this->state_ = DialState::DIAL_STATE_IDLE;
+}
+
+void OutgoingConnectionManager::schedule_wait_(uint32_t now, uint32_t wait) {
+  this->dial_socket_.reset();  // no-op when the socket was handed off
+  this->state_ = DialState::DIAL_STATE_WAITING;
+  this->state_ts_ = now;
+  this->wait_ = wait;
+}
+
+void OutgoingConnectionManager::schedule_retry_(uint32_t now) {
+  // +/-20% jitter so a fleet of devices does not retry one server in lockstep
+  const uint32_t jitter_span = this->backoff_ / 5;
+  this->schedule_wait_(now, this->backoff_ - jitter_span + (random_uint32() % (2 * jitter_span + 1)));
+  this->backoff_ = std::min(this->backoff_ * 2, BACKOFF_MAX_MS);
+}
+
+void OutgoingConnectionManager::on_client_removed(APIConnection *conn, bool was_authenticated) {
+  if (conn != this->dialed_conn_) {
+    return;
+  }
+  this->dialed_conn_ = nullptr;
+  if (was_authenticated) {
+    // A working peer (e.g. a host: target that never sends the flag)
+    // disconnected normally; state is IDLE, so loop() applies the delay
+    this->backoff_ = BACKOFF_MIN_MS;
+  } else {
+    this->schedule_retry_(App.get_loop_component_start_time());
+  }
+}
+
+void OutgoingConnectionManager::on_target_client(APIConnection *conn) {
+  // The target is connected; stop any dial in flight and reset the backoff.
+  // A dialed connection stays tracked unless it is this one: an inbound
+  // target must not orphan a still-open dial.
+  this->dial_socket_.reset();
+  if (conn == this->dialed_conn_) {
+    this->dialed_conn_ = nullptr;
+  }
+  this->state_ = DialState::DIAL_STATE_IDLE;
+  this->backoff_ = BACKOFF_MIN_MS;
+#ifndef API_OUTGOING_CONNECTION_HOST
+  SavedOutgoingTarget target{};
+  conn->get_peername_to(target.host);
+  if (target.host[0] == '\0') {
+    ESP_LOGW(TAG, "Could not read peer address; not remembering target");
+    return;
+  }
+  if (this->host_persisted_ && strcmp(target.host, this->saved_.host) == 0) {
+    return;  // unchanged and already on flash; avoid flash wear
+  }
+  // Use the fresh address this boot even if the flash write fails; a failed
+  // write is retried on the next flagged hello via host_persisted_
+  this->saved_ = target;
+  if (!this->persist_target_()) {
+    ESP_LOGW(TAG, "Failed to save target");
+    return;
+  }
+  ESP_LOGD(TAG, "Saved %s as outgoing connection target", this->saved_.host);
+#endif
+}
+
+void OutgoingConnectionManager::dump_config() const {
+  const char *host = this->target_host_();
+  if (host == nullptr) {
+    host = "none remembered yet";
+  }
+  // The boot delay differs from delay: on deep sleep builds, so print the
+  // value that actually applies
+  ESP_LOGCONFIG(TAG,
+                "  Outgoing connection port: %u\n"
+                "  Outgoing connection host: %s\n"
+                "  Outgoing connection boot delay: %" PRIu32 "ms",
+                API_OUTGOING_CONNECTION_PORT, host, BOOT_WAIT_MS);
+}
+
+}  // namespace esphome::api
+#endif  // USE_API && USE_API_OUTGOING_CONNECTION
@@ -0,0 +1,117 @@
+#pragma once
+
+#include "esphome/core/defines.h"
+#if defined(USE_API) && defined(USE_API_OUTGOING_CONNECTION)
+
+#ifdef USE_SOCKET_IMPL_LWIP_TCP
+#error "api outgoing_connection needs a socket implementation that can make outgoing connections"
+#endif
+#ifndef USE_API_NOISE
+#error "api outgoing_connection needs noise encryption so the peer is verified by key"
+#endif
+
+#include "esphome/components/socket/socket.h"
+#include "esphome/core/preferences.h"
+
+#include <memory>
+
+namespace esphome::api {
+
+class APIServer;
+class APIConnection;
+
+// Follows the build's address family (ifdef'd in socket/headers.h): toggling
+// enable_ipv6 changes the blob size, load() rejects the old blob, and the
+// target is simply relearned
+static constexpr size_t SAVED_TARGET_HOST_LEN = socket::SOCKADDR_STR_LEN;
+
+struct SavedOutgoingTarget {
+  // IP as text so the socket component's v4-mapped-IPv6 normalization is
+  // reused on both ends; empty = none remembered
+  char host[SAVED_TARGET_HOST_LEN];
+} PACKED;  // NOLINT
+
+/// Dials out when no dial-back target client is connected. Only the TCP
+/// direction flips: the device stays the Noise responder, so both sides
+/// still verify by key. Targets the YAML host or the last remembered client.
+class OutgoingConnectionManager {
+ public:
+  void setup();
+  void loop(APIServer *server);
+  /// A key-verified client declared itself a dial-back target; last one wins
+  void on_target_client(APIConnection *conn);
+  /// Clears the dialed-connection gate; dying unauthenticated escalates the backoff
+  void on_client_removed(APIConnection *conn, bool was_authenticated);
+  void on_shutdown() { this->dial_socket_.reset(); }
+  void dump_config() const;
+
+ protected:
+  enum class DialState : uint8_t {
+    DIAL_STATE_IDLE,
+    DIAL_STATE_WAITING,
+    DIAL_STATE_CONNECTING,
+  };
+
+  static constexpr uint32_t BACKOFF_MIN_MS = 5000;
+  static constexpr uint32_t BACKOFF_MAX_MS = 300000;
+  static constexpr uint32_t CONNECT_TIMEOUT_MS = 10000;
+  static constexpr uint32_t CONNECT_POLL_INTERVAL_MS = 250;
+  static constexpr uint32_t NETWORK_RETRY_MS = 500;
+  static constexpr uint32_t PRECONDITION_RETRY_MS = 5000;
+  // Boot waits for the client to connect in first; a deep sleep wake window
+  // is short, so connecting out immediately is the wake state
+#ifdef USE_DEEP_SLEEP
+  static constexpr uint32_t BOOT_WAIT_MS = 0;
+#else
+  static constexpr uint32_t BOOT_WAIT_MS = API_OUTGOING_CONNECTION_DELAY;
+#endif
+
+  void try_dial_(APIServer *server, uint32_t now);
+  void poll_connect_(APIServer *server, uint32_t now);
+  // Hand the connected socket to the server and gate on the new connection
+  void handoff_(APIServer *server, uint32_t now);
+  // Close any half-open dial and wait a jittered backoff before retrying
+  void schedule_retry_(uint32_t now);
+  // Wait without escalating the backoff (used for unmet preconditions)
+  void schedule_wait_(uint32_t now, uint32_t wait);
+#ifndef API_OUTGOING_CONNECTION_HOST
+  // Write saved_ to flash, tracking success in host_persisted_
+  bool persist_target_() {
+    this->host_persisted_ = this->target_pref_.save(&this->saved_) && global_preferences->sync();
+    return this->host_persisted_;
+  }
+#endif
+  const char *target_host_() const {
+#ifdef API_OUTGOING_CONNECTION_HOST
+    return API_OUTGOING_CONNECTION_HOST;
+#else
+    return this->saved_.host[0] != '\0' ? this->saved_.host : nullptr;
+#endif
+  }
+
+  // Pointers first (4 bytes each on 32-bit)
+  std::unique_ptr<socket::Socket> dial_socket_;
+  // Compared only, never dereferenced
+  APIConnection *dialed_conn_{nullptr};
+#ifndef API_OUTGOING_CONNECTION_HOST
+  ESPPreferenceObject target_pref_;
+#endif
+
+  // 4-byte types
+  uint32_t backoff_{BACKOFF_MIN_MS};
+  uint32_t wait_{BOOT_WAIT_MS};
+  uint32_t state_ts_{0};
+  uint32_t last_poll_{0};
+
+  // Byte-aligned types last
+#ifndef API_OUTGOING_CONNECTION_HOST
+  SavedOutgoingTarget saved_{};
+  // False while saved_ holds a value the flash write failed for; retried on
+  // the next flagged hello
+  bool host_persisted_{false};
+#endif
+  DialState state_{DialState::DIAL_STATE_WAITING};
+};
+
+}  // namespace esphome::api
+#endif  // USE_API && USE_API_OUTGOING_CONNECTION
@@ -15,6 +15,11 @@ bool HelloRequest::decode_varint(uint32_t field_id, proto_varint_value_t value)
    case 3:
      this->api_version_minor = value;
      break;
+#ifdef USE_API_OUTGOING_CONNECTION
+    case 4:
+      this->outgoing_connection_target = value != 0;
+      break;
+#endif
    default:
      return false;
  }
@@ -175,6 +180,9 @@ uint8_t *DeviceInfoResponse::encode(ProtoWriteBuffer &buffer PROTO_ENCODE_DEBUG_
 #endif
 #ifdef USE_API_NOISE
  ProtoEncode::encode_bool(pos PROTO_ENCODE_DEBUG_ARG, 26, this->api_encryption_provisionable);
+#endif
+#ifdef USE_API_OUTGOING_CONNECTION
+  ProtoEncode::encode_bool(pos PROTO_ENCODE_DEBUG_ARG, 27, this->api_outgoing_connection_supported);
 #endif
  return pos;
 }
@@ -240,6 +248,9 @@ uint32_t DeviceInfoResponse::calculate_size() const {
 #endif
 #ifdef USE_API_NOISE
  size += ProtoSize::calc_bool(2, this->api_encryption_provisionable);
+#endif
+#ifdef USE_API_OUTGOING_CONNECTION
+  size += ProtoSize::calc_bool(2, this->api_outgoing_connection_supported);
 #endif
  return size;
 }
@@ -412,13 +412,16 @@ class CommandProtoMessage : public ProtoDecodableMessage {
 class HelloRequest final : public ProtoDecodableMessage {
 public:
  static constexpr uint16_t MESSAGE_TYPE = 1;
-  static constexpr uint8_t ESTIMATED_SIZE = 17;
+  static constexpr uint8_t ESTIMATED_SIZE = 19;
 #ifdef HAS_PROTO_MESSAGE_DUMP
  const LogString *message_name() const override { return LOG_STR("hello_request"); }
 #endif
  StringRef client_info{};
  uint32_t api_version_major{0};
  uint32_t api_version_minor{0};
+#ifdef USE_API_OUTGOING_CONNECTION
+  bool outgoing_connection_target{false};
+#endif
 #ifdef HAS_PROTO_MESSAGE_DUMP
  const char *dump_to(DumpBuffer &out) const override;
 #endif
@@ -549,7 +552,7 @@ class SerialProxyInfo final : public ProtoMessage {
 class DeviceInfoResponse final : public ProtoMessage {
 public:
  static constexpr uint16_t MESSAGE_TYPE = 10;
-  static constexpr uint16_t ESTIMATED_SIZE = 312;
+  static constexpr uint16_t ESTIMATED_SIZE = 315;
 #ifdef HAS_PROTO_MESSAGE_DUMP
  const LogString *message_name() const override { return LOG_STR("device_info_response"); }
 #endif
@@ -607,6 +610,9 @@ class DeviceInfoResponse final : public ProtoMessage {
 #endif
 #ifdef USE_API_NOISE
  bool api_encryption_provisionable{false};
+#endif
+#ifdef USE_API_OUTGOING_CONNECTION
+  bool api_outgoing_connection_supported{false};
 #endif
  uint8_t *encode(ProtoWriteBuffer &buffer PROTO_ENCODE_DEBUG_PARAM) const;
  uint32_t calculate_size() const;
@@ -885,6 +885,9 @@ const char *HelloRequest::dump_to(DumpBuffer &out) const {
  dump_field(out, ESPHOME_PSTR("client_info"), this->client_info);
  dump_field(out, ESPHOME_PSTR("api_version_major"), this->api_version_major);
  dump_field(out, ESPHOME_PSTR("api_version_minor"), this->api_version_minor);
+#ifdef USE_API_OUTGOING_CONNECTION
+  dump_field(out, ESPHOME_PSTR("outgoing_connection_target"), this->outgoing_connection_target);
+#endif
  return out.c_str();
 }
 const char *HelloResponse::dump_to(DumpBuffer &out) const {
@@ -1008,6 +1011,9 @@ const char *DeviceInfoResponse::dump_to(DumpBuffer &out) const {
 #endif
 #ifdef USE_API_NOISE
  dump_field(out, ESPHOME_PSTR("api_encryption_provisionable"), this->api_encryption_provisionable);
+#endif
+#ifdef USE_API_OUTGOING_CONNECTION
+  dump_field(out, ESPHOME_PSTR("api_outgoing_connection_supported"), this->api_outgoing_connection_supported);
 #endif
  return out.c_str();
 }
@@ -34,7 +34,46 @@ APIServer::APIServer() { global_api_server = this; }
 void APIServer::socket_failed_(const LogString *msg) {
  ESP_LOGW(TAG, "Socket %s: errno %d", LOG_STR_ARG(msg), errno);
  this->destroy_socket_();
-  this->mark_failed();
+}
+
+bool APIServer::create_listen_socket_() {
+  this->socket_ = socket::socket_ip_loop_monitored(SOCK_STREAM, 0).release();  // monitored for incoming connections
+  if (this->socket_ == nullptr) {
+    this->socket_failed_(LOG_STR("creation"));
+    return false;
+  }
+  int enable = 1;
+  int err = this->socket_->setsockopt(SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int));
+  if (err != 0) {
+    ESP_LOGW(TAG, "Socket reuseaddr: errno %d", errno);
+    // we can still continue
+  }
+  err = this->socket_->setblocking(false);
+  if (err != 0) {
+    this->socket_failed_(LOG_STR("nonblocking"));
+    return false;
+  }
+
+  struct sockaddr_storage server;
+
+  socklen_t sl = socket::set_sockaddr_any((struct sockaddr *) &server, sizeof(server), this->port_);
+  if (sl == 0) {
+    this->socket_failed_(LOG_STR("set sockaddr"));
+    return false;
+  }
+
+  err = this->socket_->bind((struct sockaddr *) &server, sl);
+  if (err != 0) {
+    this->socket_failed_(LOG_STR("bind"));
+    return false;
+  }
+
+  err = this->socket_->listen(this->listen_backlog_);
+  if (err != 0) {
+    this->socket_failed_(LOG_STR("listen"));
+    return false;
+  }
+  return true;
 }

 void APIServer::setup() {
@@ -53,41 +92,14 @@ void APIServer::setup() {
 #endif
 #endif

-  this->socket_ = socket::socket_ip_loop_monitored(SOCK_STREAM, 0).release();  // monitored for incoming connections
-  if (this->socket_ == nullptr) {
-    this->socket_failed_(LOG_STR("creation"));
-    return;
-  }
-  int enable = 1;
-  int err = this->socket_->setsockopt(SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int));
-  if (err != 0) {
-    ESP_LOGW(TAG, "Socket reuseaddr: errno %d", errno);
-    // we can still continue
-  }
-  err = this->socket_->setblocking(false);
-  if (err != 0) {
-    this->socket_failed_(LOG_STR("nonblocking"));
-    return;
-  }
-
-  struct sockaddr_storage server;
-
-  socklen_t sl = socket::set_sockaddr_any((struct sockaddr *) &server, sizeof(server), this->port_);
-  if (sl == 0) {
-    this->socket_failed_(LOG_STR("set sockaddr"));
-    return;
-  }
-
-  err = this->socket_->bind((struct sockaddr *) &server, sl);
-  if (err != 0) {
-    this->socket_failed_(LOG_STR("bind"));
-    return;
-  }
-
-  err = this->socket_->listen(this->listen_backlog_);
-  if (err != 0) {
-    this->socket_failed_(LOG_STR("listen"));
+  if (!this->create_listen_socket_()) {
+#ifdef USE_API_OUTGOING_CONNECTION
+    // Dial-out needs no listener; degrade instead of stopping the component
+    this->status_set_error(LOG_STR("listen socket failed"));
+#else
+    this->mark_failed();
    return;
+#endif
  }

 #ifdef USE_LOGGER
@@ -135,6 +147,9 @@ void APIServer::setup() {
  if (this->reboot_timeout_ != 0 && !this->provisioning_pending_()) {
    this->status_set_warning(LOG_STR("waiting for client connection"));
  }
+#ifdef USE_API_OUTGOING_CONNECTION
+  this->outgoing_conn_.setup();
+#endif
 }

 void APIServer::loop() {
@@ -143,6 +158,12 @@ void APIServer::loop() {
    this->accept_new_connections_();
  }

+#ifdef USE_API_OUTGOING_CONNECTION
+  if (!this->shutting_down_) {
+    this->outgoing_conn_.loop(this);
+  }
+#endif
+
  if (this->api_connection_count_ == 0) {
    // Check reboot timeout - done in loop to avoid scheduler heap churn
    // (cancelled scheduler items sit in heap memory until their scheduled time).
@@ -151,7 +172,12 @@ void APIServer::loop() {
    if (this->reboot_timeout_ != 0 && !this->provisioning_pending_()) {
      const uint32_t now = App.get_loop_component_start_time();
      if (now - this->last_connected_ > this->reboot_timeout_) {
-        ESP_LOGE(TAG, "No clients; rebooting");
+        // Distinguish a wrong-key peer from nothing connecting at all
+        if (this->saw_unauthenticated_client_) {
+          ESP_LOGE(TAG, "Clients connected but none authenticated; rebooting");
+        } else {
+          ESP_LOGE(TAG, "No clients; rebooting");
+        }
        App.reboot();
      }
    }
@@ -203,6 +229,15 @@ void APIServer::remove_client_(uint8_t client_index) {
  std::string client_peername(client->get_peername_to(peername_buf));
 #endif

+  // Read before the swap-and-reset below destroys the connection
+  const bool was_authenticated = client->is_authenticated();
+#ifdef USE_API_OUTGOING_CONNECTION
+  if (client->flags_.outgoing_connection_target) {
+    this->outgoing_target_count_--;
+  }
+  this->outgoing_conn_.on_client_removed(client.get(), was_authenticated);
+#endif
+
  // Close socket now (was deferred from on_fatal_error to allow getpeername)
  client->helper_->close();

@@ -221,9 +256,18 @@ void APIServer::remove_client_(uint8_t client_index) {

  // Last client disconnected - set warning and start tracking for reboot timeout
  // (suppressed while provisioning is pending - see loop()).
+  // Refresh on every authenticated removal, not just the last one, so an
+  // unauthenticated straggler removed later (e.g. a port scan, or a dial to
+  // a host that accepts TCP but never speaks the API) cannot discard a
+  // healthy session's timestamp and trigger a spurious reboot
+  if (was_authenticated) {
+    this->last_connected_ = App.get_loop_component_start_time();
+    this->saw_unauthenticated_client_ = false;
+  } else {
+    this->saw_unauthenticated_client_ = true;
+  }
  if (this->api_connection_count_ == 0 && this->reboot_timeout_ != 0 && !this->provisioning_pending_()) {
    this->status_set_warning(LOG_STR("waiting for client connection"));
-    this->last_connected_ = App.get_loop_component_start_time();
  }

 #ifdef USE_API_CLIENT_DISCONNECTED_TRIGGER
@@ -245,7 +289,7 @@ void __attribute__((flatten)) APIServer::accept_new_connections_() {
    sock->getpeername_to(peername);

    // Check if we're at the connection limit
-    if (this->api_connection_count_ >= MAX_API_CONNECTIONS) {
+    if (this->at_client_limit_()) {
      ESP_LOGW(TAG, "Max connections (%d), rejecting %s", MAX_API_CONNECTIONS, peername);
      // Immediately close - socket destructor will handle cleanup
      sock.reset();
@@ -254,18 +298,54 @@ void __attribute__((flatten)) APIServer::accept_new_connections_() {

    ESP_LOGD(TAG, "Accept %s", peername);

-    auto *conn = new APIConnection(std::move(sock), this);
-    this->clients_[this->api_connection_count_++].reset(conn);
-    conn->start();
-
-    // First client connected - clear warning and update timestamp
-    if (this->api_connection_count_ == 1 && this->reboot_timeout_ != 0 && !this->provisioning_pending_()) {
-      this->status_clear_warning();
-      this->last_connected_ = App.get_loop_component_start_time();
-    }
+    this->add_client_(new APIConnection(std::move(sock), this));
  }
 }

+bool APIServer::add_client_(APIConnection *conn) {
+  if (this->at_client_limit_()) {
+    // The accept path checks first to skip the allocation; the outgoing
+    // handoff relies on this check
+    ESP_LOGW(TAG, "Max connections (%d), dropping client", MAX_API_CONNECTIONS);
+    delete conn;
+    return false;
+  }
+  this->clients_[this->api_connection_count_++].reset(conn);
+  conn->start();
+
+  // First client connected - clear warning. The reboot watchdog timestamp is
+  // refreshed when an authenticated client is removed (see remove_client_),
+  // never on bare TCP connects.
+  if (this->api_connection_count_ == 1 && this->reboot_timeout_ != 0 && !this->provisioning_pending_()) {
+    this->status_clear_warning();
+  }
+  return true;
+}
+
+#ifdef USE_API_OUTGOING_CONNECTION
+APIConnection *APIServer::add_outgoing_client_(std::unique_ptr<socket::Socket> sock) {
+  // Re-check at the handoff: the PSK may have been cleared since the dial
+  // started (mark_outgoing() needs the noise helper); add_client_ re-checks
+  // the slot limit
+  if (!this->noise_ctx_.has_psk()) {
+    ESP_LOGW(TAG, "Dropping outgoing connection (no key)");
+    return nullptr;
+  }
+  auto *conn = new APIConnection(std::move(sock), this);
+  if (!this->add_client_(conn)) {
+    return nullptr;
+  }
+  // After start(): sends our server hello first so the peer can pick the key
+  conn->mark_outgoing();
+  return conn;
+}
+
+void APIServer::on_outgoing_target_client(APIConnection *conn) {
+  this->outgoing_target_count_++;
+  this->outgoing_conn_.on_target_client(conn);
+}
+#endif
+
 void APIServer::dump_config() {
  char addr_buf[network::USE_ADDRESS_BUFFER_SIZE];
  ESP_LOGCONFIG(TAG,
@@ -282,6 +362,9 @@ void APIServer::dump_config() {
 #else
  ESP_LOGCONFIG(TAG, "  Noise encryption: NO");
 #endif
+#ifdef USE_API_OUTGOING_CONNECTION
+  this->outgoing_conn_.dump_config();
+#endif
 }

 void APIServer::handle_disconnect(APIConnection *conn) {}
@@ -577,6 +660,8 @@ bool APIServer::update_noise_psk_(const SavedNoisePsk &new_psk, const LogString
        if (!c->send_message(req)) {
          API_LOG_MSG_DROPPED(TAG, "Disconnect request");
        }
+        // Force it: a session from before the key was active must not survive
+        c->flags_.next_close = true;
      }
    });
  }
@@ -678,6 +763,9 @@ void APIServer::on_shutdown() {

  // Close the listening socket to prevent new connections
  this->destroy_socket_();
+#ifdef USE_API_OUTGOING_CONNECTION
+  this->outgoing_conn_.on_shutdown();
+#endif

  // Change batch delay to 5ms for quick flushing during shutdown
  this->batch_delay_ = 5;
@@ -11,6 +11,7 @@
 #endif
 #include "api_pb2.h"
 #include "api_pb2_service.h"
+#include "api_outgoing_connection.h"
 #include "esphome/components/socket/socket.h"
 #include "esphome/core/automation.h"
 #include "esphome/core/component.h"
@@ -86,6 +87,10 @@ class APIServer final : public Component,
  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
+#ifdef USE_API_OUTGOING_CONNECTION
+  // Called by APIConnection when a client declares itself a dial-back target in its hello
+  void on_outgoing_target_client(APIConnection *conn);
+#endif

  void handle_disconnect(APIConnection *conn);
 #ifdef USE_BINARY_SENSOR
@@ -263,6 +268,16 @@ class APIServer final : public Component,
 protected:
  // Accept incoming socket connections. Only called when socket has pending connections.
  void __attribute__((noinline)) accept_new_connections_();
+  // Insert a constructed connection into the client slots and start it.
+  // Takes ownership; deletes the connection and returns false at the limit
+  bool add_client_(APIConnection *conn);
+  bool at_client_limit_() const { return this->api_connection_count_ >= MAX_API_CONNECTIONS; }
+#ifdef USE_API_OUTGOING_CONNECTION
+  // Returns the new connection, or nullptr (socket dropped) when at the limit
+  APIConnection *add_outgoing_client_(std::unique_ptr<socket::Socket> sock);
+  bool has_outgoing_target_client_() const { return this->outgoing_target_count_ != 0; }
+  friend class OutgoingConnectionManager;
+#endif
  // Remove a disconnected client by index. Swaps with the last populated slot and resets it.
  void __attribute__((noinline)) remove_client_(uint8_t client_index);

@@ -304,6 +319,7 @@ class APIServer final : public Component,
    this->socket_ = nullptr;
  }
  void socket_failed_(const LogString *msg);
+  bool create_listen_socket_();
  // Pointers and pointer-like types first (4 bytes each)
  socket::ListenSocket *socket_{nullptr};
 #ifdef USE_API_CLIENT_CONNECTED_TRIGGER
@@ -356,8 +372,16 @@ class APIServer final : public Component,
  // 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};
-  bool shutting_down_ = false;
+  // Bit-packed so the two flags share one byte
+  bool shutting_down_ : 1 = false;
+  // For the reboot log: whether any removal since the last watchdog refresh
+  // was an unauthenticated session (e.g. a wrong-key peer)
+  bool saw_unauthenticated_client_ : 1 = false;
  uint8_t api_connection_count_{0};
+#ifdef USE_API_OUTGOING_CONNECTION
+  // Connected clients whose hello declared them a dial-back target
+  uint8_t outgoing_target_count_{0};
+#endif
 #if defined(USE_PROVISIONING) && defined(USE_API_NOISE)
  // Index assigned by the provisioning manager for reporting this transport's state.
  uint8_t provisioning_source_{0};
@@ -370,6 +394,9 @@ class APIServer final : public Component,
 #endif
  ESPPreferenceObject noise_pref_;
 #endif  // USE_API_NOISE
+#ifdef USE_API_OUTGOING_CONNECTION
+  OutgoingConnectionManager outgoing_conn_;
+#endif
 };

 extern APIServer *global_api_server;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
@@ -42,7 +42,16 @@ bool AsyncClient::connect(const char *host, uint16_t port) {
    return false;
  }

-  socket_->setblocking(false);
+  if (socket_->setblocking(false) != 0) {
+    // Capture before the log and reset() below can clobber errno; a blocking
+    // connect()/read() would otherwise stall the whole loop
+    const int saved_errno = errno;
+    ESP_LOGE(TAG, "Failed to set nonblocking: errno %d", saved_errno);
+    socket_.reset();
+    if (error_cb_)
+      error_cb_(error_arg_, this, saved_errno);
+    return false;
+  }

  int err = socket_->connect((struct sockaddr *) &addr, addrlen);
  if (err == 0) {
@@ -97,45 +106,22 @@ void AsyncClient::loop() {
    return;

  if (connecting_) {
-    // For connecting, we need to check writability, not readability
-    // The Application's select() only monitors read FDs, so we do our own check here
-    // For ESP platforms lwip_select() might be faster, but this code isn't used
-    // on those platforms anyway. If it was, we'd fix the Application select()
-    // to report writability instead of doing it this way.
-    int fd = socket_->get_fd();
-    if (fd < 0) {
-      ESP_LOGW(TAG, "Invalid socket fd");
-      close();
-      return;
-    }
-
-    fd_set writefds;
-    FD_ZERO(&writefds);
-    FD_SET(fd, &writefds);
-
-    struct timeval tv = {0, 0};
-    int ret = select(fd + 1, nullptr, &writefds, nullptr, &tv);
-
-    if (ret > 0 && FD_ISSET(fd, &writefds)) {
-      int error = 0;
-      socklen_t len = sizeof(error);
-      if (socket_->getsockopt(SOL_SOCKET, SO_ERROR, &error, &len) == 0 && error == 0) {
+    int err = 0;
+    switch (socket::poll_connect(*socket_, err)) {
+      case socket::ConnectPollResult::CONNECT_POLL_PENDING:
+        break;
+      case socket::ConnectPollResult::CONNECT_POLL_CONNECTED:
        connecting_ = false;
        connected_ = true;
        if (connect_cb_)
          connect_cb_(connect_arg_, this);
-      } else {
-        ESP_LOGW(TAG, "Connection failed: %d", error);
+        break;
+      case socket::ConnectPollResult::CONNECT_POLL_ERROR:
+        ESP_LOGW(TAG, "Connection failed: %d", err);
        close();
        if (error_cb_)
-          error_cb_(error_arg_, this, error);
-      }
-    } else if (ret < 0) {
-      const int err = errno;
-      ESP_LOGE(TAG, "Select error: %d", err);
-      close();
-      if (error_cb_)
-        error_cb_(error_arg_, this, err);
+          error_cb_(error_arg_, this, err);
+        break;
    }
  } else if (connected_) {
    // For connected sockets, use the Application's select() results
@@ -23,6 +23,7 @@ CONF_ENABLE_OTA_DOWNGRADE_PROTECTION = "enable_ota_downgrade_protection"
 CONF_ENABLED = "enabled"
 CONF_GYROSCOPE_ODR = "gyroscope_odr"
 CONF_GYROSCOPE_RANGE = "gyroscope_range"
+CONF_HOST = "host"
 CONF_IAQ = "iaq"
 CONF_IGNORE_NOT_FOUND = "ignore_not_found"
 CONF_IS_WRGB = "is_wrgb"
@@ -3,7 +3,6 @@ from pathlib import Path
 import platform
 import re
 import subprocess
-import time
 from typing import Any

 import esphome.codegen as cg
@@ -15,7 +14,6 @@ from esphome.const import (
    CONF_FRAMEWORK,
    CONF_PLATFORM_VERSION,
    CONF_SOURCE,
-    CONF_TOOLCHAIN,
    CONF_VERSION,
    KEY_CORE,
    KEY_FRAMEWORK_VERSION,
@@ -23,7 +21,6 @@ from esphome.const import (
    KEY_TARGET_PLATFORM,
    PLATFORM_ESP8266,
    ThreadModel,
-    Toolchain,
 )
 from esphome.core import (
    CORE,
@@ -38,9 +35,8 @@ from esphome.platformio.toolchain import copy_ccache_script
 from esphome.storage_json import StorageJSON
 from esphome.types import ConfigType

-from .boards import BOARDS, ESP8266_BOARD_BUILD, board_ld_script
+from .boards import BOARDS, board_ld_script
 from .const import (
-    BUILD_FLASH_MODES,
    CONF_EARLY_PIN_INIT,
    CONF_ENABLE_SERIAL,
    CONF_ENABLE_SERIAL1,
@@ -48,7 +44,6 @@ from .const import (
    KEY_BOARD,
    KEY_ESP8266,
    KEY_PIN_INITIAL_STATES,
-    KEY_SCANF_FLOAT,
    KEY_SERIAL1_REQUIRED,
    KEY_SERIAL_REQUIRED,
    KEY_WAVEFORM_REQUIRED,
@@ -108,53 +103,6 @@ def set_core_data(config: ConfigType) -> ConfigType:
    return config


-_TOOLCHAINS = (Toolchain.PLATFORMIO, Toolchain.ARDUINO)
-_validate_toolchain = cv.toolchain_enum(_TOOLCHAINS)
-_resolve_toolchain = cv.resolve_toolchain("ESP8266", _TOOLCHAINS, Toolchain.PLATFORMIO)
-
-
-def _validate_native_toolchain(config: ConfigType) -> ConfigType:
-    """Constraints of the native (non-PlatformIO) Arduino toolchain."""
-    if not CORE.using_toolchain_arduino:
-        return config
-    from esphome.arduino8266.framework import MIN_FRAMEWORK_VERSION
-
-    conf = config[CONF_FRAMEWORK]
-    version = cv.Version.parse(conf[CONF_VERSION])
-    if version < MIN_FRAMEWORK_VERSION:
-        raise cv.Invalid(
-            "'toolchain: arduino' requires framework version "
-            f"{MIN_FRAMEWORK_VERSION} or newer"
-        )
-    # platform_version is a PlatformIO concept; drop it (as esp32's native
-    # toolchain does), warning when a custom pin is discarded. The floor
-    # above guarantees the schema-derived default is the ARDUINO_4 spec.
-    if (
-        conf.pop(CONF_PLATFORM_VERSION, _ARDUINO_4_PLATFORM_SPEC)
-        != _ARDUINO_4_PLATFORM_SPEC
-    ):
-        _LOGGER.warning(
-            "'platform_version' is ignored by 'toolchain: arduino'; the native "
-            "toolchain downloads the framework and compiler directly"
-        )
-    if conf[CONF_SOURCE] != _format_framework_arduino_version(version):
-        raise cv.Invalid(
-            "'toolchain: arduino' does not support a custom framework source; "
-            "use 'toolchain: platformio'"
-        )
-    # BOARDS is a subset of ESP8266_BOARD_BUILD today; the second clause is
-    # a drift guard for the independently regenerated tables
-    if (
-        config[CONF_BOARD] not in BOARDS
-        or config[CONF_BOARD] not in ESP8266_BOARD_BUILD
-    ):
-        raise cv.Invalid(
-            f"Board '{config[CONF_BOARD]}' is not supported by "
-            "'toolchain: arduino'; use 'toolchain: platformio'"
-        )
-    return config
-
-
 def get_download_types(storage_json: StorageJSON) -> list[dict[str, str]]:
    """Binary-download entries for a built ESP8266 firmware.

@@ -184,7 +132,7 @@ def _format_framework_arduino_version(ver: cv.Version) -> str:
    # a PIO platformio/framework-arduinoespressif8266 value
    # List of package versions: https://api.registry.platformio.org/v3/packages/platformio/tool/framework-arduinoespressif8266
    # Same encoding the native toolchain uses for its package download, so a
-    # custom-source check against this value cannot drift from what it fetches.
+    # version bump cannot drift between the two paths.
    from esphome.arduino8266.framework import framework_package_version

    try:
@@ -246,7 +194,7 @@ def _arduino_check_versions(value: ConfigType) -> ConfigType:
    platform_version = value.get(CONF_PLATFORM_VERSION)
    if platform_version is None:
        if version >= cv.Version(3, 1, 0):
-            platform_version = _ARDUINO_4_PLATFORM_SPEC
+            platform_version = _parse_platform_version(str(ARDUINO_4_PLATFORM_VERSION))
        else:
            platform_version = _parse_platform_version(str(ARDUINO_3_PLATFORM_VERSION))
    value[CONF_PLATFORM_VERSION] = platform_version
@@ -269,10 +217,6 @@ def _parse_platform_version(value: Any) -> str:
        return value


-# The platform_version derived for every core >= 3.1.0 config
-_ARDUINO_4_PLATFORM_SPEC = _parse_platform_version(str(ARDUINO_4_PLATFORM_VERSION))
-
-
 ARDUINO_FRAMEWORK_SCHEMA = cv.All(
    cv.Schema(
        {
@@ -289,6 +233,7 @@ ARDUINO_FRAMEWORK_SCHEMA = cv.All(
 )


+BUILD_FLASH_MODES = ["qio", "qout", "dio", "dout"]
 CONFIG_SCHEMA = cv.All(
    cv.Schema(
        {
@@ -305,30 +250,15 @@ CONFIG_SCHEMA = cv.All(
            cv.Optional(CONF_ENABLE_SERIAL1): cv.boolean,
            cv.Optional(CONF_ENABLE_FULL_PRINTF, default=False): cv.boolean,
            cv.Optional(CONF_ENABLE_SCANF_FLOAT): cv.boolean,
-            cv.Optional(
-                CONF_TOOLCHAIN, visibility=cv.Visibility.ADVANCED
-            ): _validate_toolchain,
        }
    ),
-    _resolve_toolchain,
-    _validate_native_toolchain,
+    # Until the native toolchain lands, PlatformIO is the only backend;
+    # reject a --toolchain this platform cannot serve yet.
+    cv.require_platformio_toolchain("ESP8266"),
    set_core_data,
 )


-def native_toolchain_module():
-    """The native build backend for the resolved toolchain, if any.
-
-    ``__main__`` dispatches from its own toolchain-keyed table; this helper
-    serves the component's internal callers.
-    """
-    if not CORE.using_toolchain_arduino:
-        return None
-    from esphome.arduino8266 import toolchain
-
-    return toolchain
-
-
 def check_rosetta() -> None:
    """Fail fast when the x86_64 ESP8266 toolchain cannot run on this Mac.

@@ -364,13 +294,12 @@ def _choose_ld_script(board: str) -> str:

@coroutine_with_priority(CoroPriority.PLATFORM)
 async def to_code(config: ConfigType) -> None:
-    use_platformio = CORE.using_toolchain_platformio
    cg.add(esp8266_ns.setup_preferences())

-    if use_platformio:
-        cg.add_platformio_option("lib_ldf_mode", "off")
-        cg.add_platformio_option("lib_compat_mode", "strict")
-        cg.add_platformio_option("board", config[CONF_BOARD])
+    cg.add_platformio_option("lib_ldf_mode", "off")
+    cg.add_platformio_option("lib_compat_mode", "strict")
+
+    cg.add_platformio_option("board", config[CONF_BOARD])
    cg.add_build_flag("-DUSE_ESP8266")
    cg.set_cpp_standard("gnu++20")
    cg.add_define("ESPHOME_BOARD", config[CONF_BOARD])
@@ -386,32 +315,28 @@ async def to_code(config: ConfigType) -> None:
            "enabling scanf float support (~8KB flash)"
        )

-    # The native generator reads the same decision (KEY_SCANF_FLOAT)
-    CORE.data[KEY_ESP8266][KEY_SCANF_FLOAT] = bool(enable_scanf_float)
-    if use_platformio:
-        extra_scripts = [
-            "pre:ccache.py",
-            "pre:testing_mode.py",
-            "pre:exclude_updater.py",
-            "pre:exclude_waveform.py",
-            "pre:relocate_ratetable.py",
-        ]
-        if not enable_scanf_float:
-            extra_scripts.append("pre:remove_float_scanf.py")
-        extra_scripts.append("post:post_build.py")
-        cg.add_platformio_option("extra_scripts", extra_scripts)
+    extra_scripts = [
+        "pre:ccache.py",
+        "pre:testing_mode.py",
+        "pre:exclude_updater.py",
+        "pre:exclude_waveform.py",
+        "pre:relocate_ratetable.py",
+    ]
+    if not enable_scanf_float:
+        extra_scripts.append("pre:remove_float_scanf.py")
+    extra_scripts.append("post:post_build.py")
+    cg.add_platformio_option("extra_scripts", extra_scripts)

    conf = config[CONF_FRAMEWORK]
+    cg.add_platformio_option("framework", "arduino")
    cg.add_build_flag("-DUSE_ARDUINO")
    cg.add_build_flag("-DUSE_ESP8266_FRAMEWORK_ARDUINO")
    cg.add_build_flag("-Wno-nonnull-compare")
-    if use_platformio:
-        cg.add_platformio_option("framework", "arduino")
-        cg.add_platformio_option("platform", conf[CONF_PLATFORM_VERSION])
-        cg.add_platformio_option(
-            "platform_packages",
-            [f"platformio/framework-arduinoespressif8266@{conf[CONF_SOURCE]}"],
-        )
+    cg.add_platformio_option("platform", conf[CONF_PLATFORM_VERSION])
+    cg.add_platformio_option(
+        "platform_packages",
+        [f"platformio/framework-arduinoespressif8266@{conf[CONF_SOURCE]}"],
+    )

    # Default for platformio is LWIP2_LOW_MEMORY with:
    #  - MSS=536
@@ -449,8 +374,7 @@ async def to_code(config: ConfigType) -> None:
    # Force-include inline std::__throw_* overrides so GCC dead-strips the unused
    # libstdc++ error message strings (e.g. "basic_string::_M_create") from DRAM.
    # See throw_stubs.h for details. Must be prepended before <string>, so this
-    # uses build_src_flags with -include. Unconditional: the native build
-    # generator reads the same option, keeping one source of truth.
+    # uses build_src_flags with -include.
    cg.add_platformio_option(
        "build_src_flags", "-include esphome/components/esp8266/throw_stubs.h"
    )
@@ -480,8 +404,6 @@ async def to_code(config: ConfigType) -> None:
    # implementation in the Arduino ESP8266 core.
    cg.add_build_flag("-Wl,--wrap=millis")

-    # Unconditional: the native build generator reads the same option,
-    # keeping one source of truth
    cg.add_platformio_option("board_build.flash_mode", config[CONF_BOARD_FLASH_MODE])

    ver: cv.Version = CORE.data[KEY_CORE][KEY_FRAMEWORK_VERSION]
@@ -490,7 +412,7 @@ async def to_code(config: ConfigType) -> None:
        cg.RawExpression(f"VERSION_CODE({ver.major}, {ver.minor}, {ver.patch})"),
    )

-    if use_platformio and config[CONF_BOARD] in BOARDS:
+    if config[CONF_BOARD] in BOARDS:
        cg.add_platformio_option(
            "board_build.ldscript", _choose_ld_script(config[CONF_BOARD])
        )
@@ -531,24 +453,8 @@ async def finalize_serial_config() -> None:
        cg.add_build_flag("-DNO_GLOBAL_SERIAL1")


-# Called by __main__.compile_program; returning False falls through to the
-# PlatformIO toolchain.
-def run_compile(args, config: ConfigType) -> bool:
-    # Positive check: the native backend only runs when explicitly resolved
-    toolchain = native_toolchain_module()
-    if toolchain is None:
-        return False
-    if toolchain.run_compile(config, CORE.verbose) != 0:
-        raise EsphomeError("ESP8266 native build failed")
-    return True
-
-
 # Called by writer.py
 def copy_files() -> None:
-    # Native builds skip the PlatformIO extra scripts; the build generator
-    # carries their logic
-    if CORE.using_toolchain_arduino:
-        return
    dir = Path(__file__).parent
    for script in (
        "post_build",
@@ -605,75 +511,22 @@ ESP8266_EXCEPTION_CODES = {
 }


-_DECODE_WARNED_AT: dict[str, float] = {}
+def _decode_pc(config: ConfigType, addr: str) -> None:
+    from esphome.platformio import toolchain

-
-def _warn_decode_problem(key: str, message: str, *args) -> bool:
-    """Warn, deduplicated briefly so a burst of stack-dump addresses warns
-    once but a later dump warns again; returns whether it warned so the
-    caller can mark suppressed addresses individually."""
-    now = time.monotonic()
-    last = _DECODE_WARNED_AT.get(key)
-    if last is not None and now - last < 30:
-        return False
-    _DECODE_WARNED_AT[key] = now
-    _LOGGER.warning(message, *args)
-    return True
-
-
-def _decode_pc(config: ConfigType, addr: str, *, bulk: bool = False) -> None:
-    """Decode one crash address. ``bulk``: the caller is scanning every
-    8-hex stack word, most of which are not code addresses -- unmappable
-    ones log at debug so real frames are not buried."""
-    if (native_toolchain := native_toolchain_module()) is not None:
-        addr2line = native_toolchain.get_addr2line_path()
-        elf = native_toolchain.get_elf_path()
-        for path in (addr2line, elf):
-            if not path.is_file():
-                _warn_decode_problem(
-                    str(path), "Cannot decode crash addresses: %s missing", path
-                )
-                # The detailed warning names no address; mark named
-                # registers, but bulk stack words at debug (~150 per dump)
-                log = _LOGGER.debug if bulk else _LOGGER.warning
-                log("Not decoded %s (toolchain file missing)", addr)
-                return
-        addr2line, elf = str(addr2line), str(elf)
-    else:
-        from esphome.platformio import toolchain
-
-        idedata = toolchain.get_idedata(config)
-        if not idedata.addr2line_path or not idedata.firmware_elf_path:
-            _warn_decode_problem(
-                "no-addr2line",
-                "Cannot decode crash addresses: no addr2line or ELF in idedata",
-            )
-            log = _LOGGER.debug if bulk else _LOGGER.warning
-            log("Not decoded %s (no addr2line or ELF)", addr)
-            return
-        addr2line, elf = idedata.addr2line_path, idedata.firmware_elf_path
-    command = [addr2line, "-pfiaC", "-e", elf, addr]
+    idedata = toolchain.get_idedata(config)
+    if not idedata.addr2line_path or not idedata.firmware_elf_path:
+        _LOGGER.debug("decode_pc no addr2line")
+        return
+    command = [idedata.addr2line_path, "-pfiaC", "-e", idedata.firmware_elf_path, addr]
    try:
        translation = subprocess.check_output(command, close_fds=False).decode().strip()
-    except Exception as err:  # noqa: BLE001  # pylint: disable=broad-except
-        # Warn, not debug: a failing addr2line must be visible. The warning
-        # is rate-limited across a dump, so mark every undecoded address
-        # inline or the rest read as merely unmappable
-        if not _warn_decode_problem(
-            "addr2line-failed", "Could not decode crash address %s (%s)", addr, err
-        ):
-            # The detailed warning already named this address; mark only
-            # the rate-limited ones, and bulk stack words at debug
-            log = _LOGGER.debug if bulk else _LOGGER.warning
-            log("Not decoded %s (addr2line failed)", addr)
+    except Exception:  # noqa: BLE001  # pylint: disable=broad-except
        _LOGGER.debug("Caught exception for command %s", command, exc_info=1)
        return

    if "?? ??:0" in translation:
-        # A named register that fails to decode is confusing silence; a
-        # bulk stack word failing is the expected common case
-        log = _LOGGER.debug if bulk else _LOGGER.warning
-        log("Not decoded %s (address not in %s)", addr, elf)
+        # Nothing useful
        return
    translation = translation.replace(" at ??:?", "").replace(":?", "")
    _LOGGER.warning("Decoded %s", translation)
@@ -743,6 +596,6 @@ def process_stacktrace(config: ConfigType, line: str, backtrace_state: bool) ->

    if backtrace_state:
        for addr in re.finditer(STACKTRACE_ESP8266_BACKTRACE_PC_RE, line):
-            _decode_pc(config, addr.group(), bulk=True)
+            _decode_pc(config, addr.group())

    return backtrace_state
@@ -16,6 +16,7 @@ KEY_WAVEFORM_REQUIRED = "waveform_required"
 KEY_SERIAL_REQUIRED = "serial_required"
 KEY_SERIAL1_REQUIRED = "serial1_required"
 # Set for the native (non-PlatformIO) toolchain's build generator
+KEY_FLASH_MODE = "flash_mode"
 KEY_SCANF_FLOAT = "scanf_float"
 # Per-board flash-layout override consumed by board_ld_script()
 KEY_LDSCRIPT = "ldscript"
@@ -72,6 +73,3 @@ def enable_serial1() -> None:
            enable_serial1()
    """
    CORE.data.setdefault(KEY_ESP8266, {})[KEY_SERIAL1_REQUIRED] = True
-
-
-BUILD_FLASH_MODES = ("qio", "qout", "dio", "dout")
@@ -444,7 +444,10 @@ void ESPHomeOTAComponent::handle_data_() {
  tv.tv_usec = 0;
  this->client_->setsockopt(SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
  this->client_->setsockopt(SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
-  this->client_->setblocking(true);
+  if (this->client_->setblocking(true) != 0) {
+    this->log_socket_error_(LOG_STR("blocking"));
+    goto error;  // NOLINT(cppcoreguidelines-avoid-goto)
+  }

  // Acknowledge auth OK - 1 byte
  this->data_write_byte_(ota::OTA_RESPONSE_AUTH_OK);
@@ -17,6 +17,8 @@ CONF_IMPLEMENTATION = "implementation"
 IMPLEMENTATION_LWIP_TCP = "lwip_tcp"
 IMPLEMENTATION_LWIP_SOCKETS = "lwip_sockets"
 IMPLEMENTATION_BSD_SOCKETS = "bsd_sockets"
+# Implementations whose sockets cannot make outgoing connections
+IMPLEMENTATIONS_WITHOUT_CONNECT = frozenset({IMPLEMENTATION_LWIP_TCP})

 # Socket tracking infrastructure
 # Components register their socket needs and platforms read this to configure appropriately
@@ -59,13 +59,15 @@ int BSDSocketImpl::close() {

 int BSDSocketImpl::setblocking(bool blocking) {
  int fl = ::fcntl(this->fd_, F_GETFL, 0);
+  if (fl < 0) {
+    return fl;
+  }
  if (blocking) {
    fl &= ~O_NONBLOCK;
  } else {
    fl |= O_NONBLOCK;
  }
-  ::fcntl(this->fd_, F_SETFL, fl);
-  return 0;
+  return ::fcntl(this->fd_, F_SETFL, fl);
 }

 size_t BSDSocketImpl::getpeername_to(std::span<char, SOCKADDR_STR_LEN> buf) {
@@ -49,13 +49,15 @@ int LwIPSocketImpl::close() {

 int LwIPSocketImpl::setblocking(bool blocking) {
  int fl = lwip_fcntl(this->fd_, F_GETFL, 0);
+  if (fl < 0) {
+    return fl;
+  }
  if (blocking) {
    fl &= ~O_NONBLOCK;
  } else {
    fl |= O_NONBLOCK;
  }
-  lwip_fcntl(this->fd_, F_SETFL, fl);
-  return 0;
+  return lwip_fcntl(this->fd_, F_SETFL, fl);
 }

 size_t LwIPSocketImpl::getpeername_to(std::span<char, SOCKADDR_STR_LEN> buf) {
@@ -2,6 +2,9 @@
 #if defined(USE_SOCKET_IMPL_LWIP_TCP) || defined(USE_SOCKET_IMPL_LWIP_SOCKETS) || defined(USE_SOCKET_IMPL_BSD_SOCKETS)
 #include <cerrno>
 #include <cstring>
+#ifdef USE_SOCKET_IMPL_BSD_SOCKETS
+#include <sys/select.h>
+#endif
 #include <string>
 #include "esphome/core/log.h"
 #include "esphome/core/application.h"
@@ -165,7 +168,10 @@ socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const char *ip_
 #else
    // Use LWIP-specific functions
    ip6_addr_t ip6;
-    inet6_aton(ip_address, &ip6);
+    if (inet6_aton(ip_address, &ip6) == 0) {
+      errno = EINVAL;
+      return 0;
+    }
    memcpy(server->sin6_addr.un.u32_addr, ip6.addr, sizeof(ip6.addr));
 #endif
    return sizeof(sockaddr_in6);
@@ -185,12 +191,58 @@ socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const char *ip_
    return 0;
  }
 #else
-  server->sin_addr.s_addr = inet_addr(ip_address);
+  // Unlike inet_addr(), inet_aton() can signal failure while still
+  // accepting the broadcast address 255.255.255.255
+  if (inet_aton(ip_address, &server->sin_addr) == 0) {
+    errno = EINVAL;
+    return 0;
+  }
 #endif
  server->sin_port = htons(port);
  return sizeof(sockaddr_in);
 }

+#if defined(USE_SOCKET_IMPL_BSD_SOCKETS) || defined(USE_SOCKET_IMPL_LWIP_SOCKETS)
+ConnectPollResult poll_connect(Socket &sock, int &err_out) {
+  int fd = sock.get_fd();
+  if (fd < 0 || fd >= FD_SETSIZE) {
+    // FD_SET on either is undefined behavior
+    err_out = EBADF;
+    return ConnectPollResult::CONNECT_POLL_ERROR;
+  }
+  // Connect completion is a write event; the main loop only selects on reads
+  fd_set writefds;
+  FD_ZERO(&writefds);
+  FD_SET(fd, &writefds);
+  struct timeval tv = {0, 0};
+#ifdef USE_SOCKET_IMPL_LWIP_SOCKETS
+  // LWIP_COMPAT_SOCKETS may be off (LibreTiny), so use the lwip symbol directly
+  int ret = lwip_select(fd + 1, nullptr, &writefds, nullptr, &tv);
+#else
+  // Global-scope select: the entity namespace esphome::select shadows it here
+  int ret = ::select(fd + 1, nullptr, &writefds, nullptr, &tv);
+#endif
+  if (ret < 0) {
+    err_out = errno;
+    return ConnectPollResult::CONNECT_POLL_ERROR;
+  }
+  if (ret == 0 || !FD_ISSET(fd, &writefds)) {
+    return ConnectPollResult::CONNECT_POLL_PENDING;
+  }
+  int error = 0;
+  socklen_t len = sizeof(error);
+  if (sock.getsockopt(SOL_SOCKET, SO_ERROR, &error, &len) != 0) {
+    err_out = errno;
+    return ConnectPollResult::CONNECT_POLL_ERROR;
+  }
+  if (error != 0) {
+    err_out = error;
+    return ConnectPollResult::CONNECT_POLL_ERROR;
+  }
+  return ConnectPollResult::CONNECT_POLL_CONNECTED;
+}
+#endif
+
 socklen_t set_sockaddr_any(struct sockaddr *addr, socklen_t addrlen, uint16_t port) {
 #if USE_NETWORK_IPV6
  if (addrlen < sizeof(sockaddr_in6)) {
@@ -145,6 +145,19 @@ inline socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const st
 /// Set a sockaddr to the any address and specified port for the IP version used by socket_ip().
 socklen_t set_sockaddr_any(struct sockaddr *addr, socklen_t addrlen, uint16_t port);

+#if defined(USE_SOCKET_IMPL_BSD_SOCKETS) || defined(USE_SOCKET_IMPL_LWIP_SOCKETS)
+enum class ConnectPollResult : uint8_t {
+  CONNECT_POLL_PENDING,
+  CONNECT_POLL_CONNECTED,
+  CONNECT_POLL_ERROR,
+};
+
+/// Check a non-blocking connect() for completion without blocking. On
+/// CONNECT_POLL_ERROR, err_out holds the socket's SO_ERROR, or errno when the
+/// poll itself failed.
+ConnectPollResult poll_connect(Socket &sock, int &err_out);
+#endif
+
 /// Format sockaddr into caller-provided buffer, returns length written (excluding null)
 size_t format_sockaddr_to(const struct sockaddr *addr_ptr, socklen_t len, std::span<char, SOCKADDR_STR_LEN> buf);

@@ -1,5 +1,6 @@
 import esphome.codegen as cg
 from esphome.components import binary_sensor, sensor
+from esphome.components.const import CONF_HOST
 import esphome.config_validation as cv
 from esphome.const import (
    CONF_BINARY_SENSORS,
@@ -14,7 +15,6 @@ AUTO_LOAD = ["socket"]
 CODEOWNERS = ["@Links2004"]
 DEPENDENCIES = ["network"]

-CONF_HOST = "host"
 CONF_PREFIX = "prefix"

 statsd_component_ns = cg.esphome_ns.namespace("statsd")
@@ -13,9 +13,16 @@ void UDPComponent::setup() {
 #if defined(USE_SOCKET_IMPL_BSD_SOCKETS) || defined(USE_SOCKET_IMPL_LWIP_SOCKETS)
  for (const auto &address : this->addresses_) {
    struct sockaddr saddr {};
-    socket::set_sockaddr(&saddr, sizeof(saddr), address, this->broadcast_port_);
+    if (socket::set_sockaddr(&saddr, sizeof(saddr), address, this->broadcast_port_) == 0) {
+      ESP_LOGW(TAG, "Invalid address %s", address);
+      continue;
+    }
    this->sockaddrs_.push_back(saddr);
  }
+  if (this->sockaddrs_.size() != this->addresses_.size()) {
+    // A dropped address silently receives nothing; surface the misconfiguration
+    this->status_set_warning(LOG_STR("invalid address"));
+  }
  // set up broadcast socket
  if (this->should_broadcast_) {
    this->broadcast_socket_ = socket::socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
@@ -94,9 +101,15 @@ void UDPComponent::setup() {
  // 8266 and RP2040 `Duino
  for (const auto &address : this->addresses_) {
    auto ipaddr = IPAddress();
-    ipaddr.fromString(address);
+    if (!ipaddr.fromString(address)) {
+      ESP_LOGW(TAG, "Invalid address %s", address);
+      continue;
+    }
    this->ipaddrs_.push_back(ipaddr);
  }
+  if (this->ipaddrs_.size() != this->addresses_.size()) {
+    this->status_set_warning(LOG_STR("invalid address"));
+  }
  if (this->should_listen_)
    this->udp_client_.begin(this->listen_port_);
 #endif
@@ -34,6 +34,10 @@ void WakeOnLanButton::press_action() {
  struct sockaddr_storage saddr {};
  auto addr_len =
      socket::set_sockaddr(reinterpret_cast<sockaddr *>(&saddr), sizeof(saddr), "255.255.255.255", this->port_);
+  if (addr_len == 0) {
+    ESP_LOGW(TAG, "Invalid broadcast address");
+    return;
+  }
  uint8_t buffer[6 + sizeof this->macaddr_ * 16];
  memcpy(buffer, PREFIX, sizeof(PREFIX));
  for (size_t i = 0; i != 16; i++) {
@@ -555,14 +555,7 @@ NATIVE_ARDUINO_PIO_OPTIONS = frozenset({"board_build.f_cpu", "board_build.ldscri
 # that is stored rather than translated away. Consumed by the esp8266 native
 # backend (later in this chain) for its ignored-option warning; defined here
 # so it stays adjacent to the routing.
-# build_src_flags and board_build.flash_mode: set unconditionally by
-# esp8266/__init__ and read by the native generator; not user-routable, so
-# not in the set above
-NATIVE_ARDUINO_CONSUMED_PIO_OPTIONS = NATIVE_ARDUINO_PIO_OPTIONS | {
-    "lib_ignore",
-    "build_src_flags",
-    "board_build.flash_mode",
-}
+NATIVE_ARDUINO_CONSUMED_PIO_OPTIONS = NATIVE_ARDUINO_PIO_OPTIONS | {"lib_ignore"}


@coroutine_with_priority(CoroPriority.FINAL)
@@ -216,6 +216,11 @@
 #define USE_API_HOMEASSISTANT_SERVICES
 #define USE_API_HOMEASSISTANT_STATES
 #define USE_API_NOISE
+#if !defined(USE_ESP8266) && !defined(USE_RP2)  // raw-lwip sockets cannot make outgoing connections
+#define USE_API_OUTGOING_CONNECTION
+#define API_OUTGOING_CONNECTION_PORT 6054
+#define API_OUTGOING_CONNECTION_DELAY 60000
+#endif
 #define USE_API_VARINT64
 #define USE_API_PLAINTEXT
 #define USE_API_USER_DEFINED_ACTIONS
@@ -610,15 +610,10 @@ def clean_build(clear_pio_cache: bool = True, *, full: bool = False):
                _LOGGER.info("Deleting %s", idf_path)
                rmtree(idf_path)

-    # The idedata caches are derived from the build but live under the data
-    # dir, not the build path, so they must be removed separately in both
-    # modes. Globbed (name.json plus name.<backend>.json) so a future
-    # backend suffix cannot silently drift out of clean-all.
-    idedata_dir = CORE.relative_internal_path("idedata")
-    for idedata_cache in (
-        *idedata_dir.glob(f"{CORE.name}.json"),
-        *idedata_dir.glob(f"{CORE.name}.*.json"),
-    ):
+    # The idedata cache is derived from the build but lives under the data dir,
+    # not the build path, so it must be removed separately in both modes.
+    idedata_cache = CORE.relative_internal_path("idedata", f"{CORE.name}.json")
+    if idedata_cache.is_file():
        _LOGGER.info("Deleting %s", idedata_cache)
        idedata_cache.unlink()

@@ -50,7 +50,6 @@ from __future__ import annotations

 import argparse
 from collections import Counter
-from collections.abc import Callable
 from enum import StrEnum
 from functools import cache
 import json
@@ -532,53 +531,37 @@ ESP32_PLATFORMIO_TRIGGER_PATH_PREFIXES = ("esphome/platformio/",)
 #   - esphome/build_gen/platformio.py -- the PlatformIO build generator
 #   - script/test_build_components.py -- the harness the job invokes
 #   - .github/workflows/ci.yml -- the job's own definition
-# Shared by every toolchain smoke-test job: the harness it invokes and the
-# workflow that defines it
-_SMOKE_HARNESS_TRIGGER_FILES = frozenset(
+ESP32_PLATFORMIO_TRIGGER_FILES = frozenset(
    {
+        "esphome/build_gen/platformio.py",
        "script/test_build_components.py",
        ".github/workflows/ci.yml",
    }
 )

-ESP32_PLATFORMIO_TRIGGER_FILES = _SMOKE_HARNESS_TRIGGER_FILES | {
-    "esphome/build_gen/platformio.py",
-}
-
-
-def _path_or_file_trigger(
-    files: list[str],
-    trigger_files: frozenset[str],
-    trigger_prefixes: tuple[str, ...],
-) -> bool:
-    """Whether any changed file matches the given infrastructure triggers."""
-    return any(
-        file in trigger_files or file.startswith(trigger_prefixes) for file in files
-    )
-
-
-@cache
-def _cached_components_closure(files: tuple[str, ...]) -> frozenset[str]:
-    """Dependency closure of the changed components, from the changed files.
-
-    The walk is expensive and every toolchain smoke-test job asks for the
-    same file list, so compute it once per run."""
-    component_files = [f for f in files if filter_component_and_test_files(f)]
-    return frozenset(get_components_with_dependencies(component_files, True))
-

 def _esp32_platformio_path_or_file_trigger(files: list[str]) -> bool:
    """Whether any changed file is a PlatformIO infrastructure / harness trigger."""
-    return _path_or_file_trigger(
-        files, ESP32_PLATFORMIO_TRIGGER_FILES, ESP32_PLATFORMIO_TRIGGER_PATH_PREFIXES
-    )
+    for file in files:
+        if file in ESP32_PLATFORMIO_TRIGGER_FILES:
+            return True
+        if any(
+            file.startswith(prefix) for prefix in ESP32_PLATFORMIO_TRIGGER_PATH_PREFIXES
+        ):
+            return True
+    return False


 def _esp_idf_infra_changed(files: list[str]) -> bool:
    """Whether any changed file is ESP-IDF build/runner infrastructure."""
-    return _path_or_file_trigger(
-        files, ESP_IDF_INFRA_TRIGGER_FILES, ESP_IDF_INFRA_TRIGGER_PATH_PREFIXES
-    )
+    for file in files:
+        if file in ESP_IDF_INFRA_TRIGGER_FILES:
+            return True
+        if any(
+            file.startswith(prefix) for prefix in ESP_IDF_INFRA_TRIGGER_PATH_PREFIXES
+        ):
+            return True
+    return False


 def esp32_platformio_components_to_test(branch: str | None = None) -> list[str]:
@@ -616,23 +599,15 @@ def esp32_platformio_components_to_test(branch: str | None = None) -> list[str]:
    Returns:
        Sorted list of component names to compile.
    """
-    return _toolchain_components_to_test(
-        branch, ESP32_PLATFORMIO_TEST_COMPONENTS, _esp32_platformio_path_or_file_trigger
-    )
-
-
-def _toolchain_components_to_test(
-    branch: str | None,
-    test_set: frozenset[str],
-    infra_trigger: Callable[[list[str]], bool],
-) -> list[str]:
-    """The shared narrowing rule for the per-toolchain smoke-test jobs."""
    files = changed_files(branch)

-    if core_changed(files) or infra_trigger(files):
-        return sorted(test_set)
+    if core_changed(files) or _esp32_platformio_path_or_file_trigger(files):
+        return sorted(ESP32_PLATFORMIO_TEST_COMPONENTS)

-    return sorted(test_set & _cached_components_closure(tuple(files)))
+    component_files = [f for f in files if filter_component_and_test_files(f)]
+    changed = get_components_with_dependencies(component_files, True)
+
+    return sorted(ESP32_PLATFORMIO_TEST_COMPONENTS & set(changed))


 def should_run_esp32_platformio(branch: str | None = None) -> bool:
@@ -653,83 +628,6 @@ def should_run_esp32_platformio(branch: str | None = None) -> bool:
    return bool(esp32_platformio_components_to_test(branch))


-# The `--toolchain arduino` smoke-test set: covers the core, the bundled and
-# converted registry libraries, and the waveform path.
-ESP8266_NATIVE_TEST_COMPONENTS = frozenset(
-    {
-        "esp8266",
-        "api",
-        "web_server",
-        "captive_portal",
-        "mqtt",
-        "esp8266_pwm",
-        "neopixelbus",
-        "bme280_i2c",
-        "uart",
-    }
-)
-
-# Infrastructure whose changes always trigger the native ESP8266 compile
-# test. esphome/build_helpers/ holds the idedata and size-summary helpers
-# the backend shares with the native ESP-IDF build.
-ESP8266_NATIVE_TRIGGER_PATH_PREFIXES = (
-    "esphome/arduino8266/",
-    "esphome/arduino/",
-    "esphome/build_helpers/",
-)
-# Shared library-conversion modules every native build imports; espidf-only
-# infra (build_gen/espidf.py) deliberately stays out of the esp8266 set.
-_NATIVE_SHARED_TRIGGER_FILES = frozenset(
-    {
-        "esphome/framework_helpers.py",
-        "esphome/platformio/library.py",
-        "esphome/platformio/extra_script.py",
-    }
-)
-# Tripwire: the shared modules must stay in the ESP-IDF trigger set too
-# (now defined in clang_tidy_hash), or its smoke test silently skips them
-assert _NATIVE_SHARED_TRIGGER_FILES <= ESP_IDF_INFRA_TRIGGER_FILES
-ESP8266_NATIVE_TRIGGER_FILES = (
-    _NATIVE_SHARED_TRIGGER_FILES
-    | _SMOKE_HARNESS_TRIGGER_FILES
-    | {
-        "esphome/build_gen/arduino8266.py",
-        "esphome/build_gen/build_tool.py",
-        "esphome/components/esp8266/build_surgery.py",
-        "esphome/components/esp8266/boards.py",
-        "esphome/platformio/registry.py",
-        # esp8266/__init__.py imports copy_ccache_script from it
-        "esphome/platformio/toolchain.py",
-        ".github/actions/cache-arduino8266/action.yml",
-    }
-)
-
-
-def _esp8266_native_path_or_file_trigger(files: list[str]) -> bool:
-    """Whether any changed file is native-ESP8266 infrastructure / harness."""
-    # base_python_changed covers the top-level esphome/*.py modules the
-    # native backend imports directly (framework_helpers, helpers, writer,
-    # __main__); without it a change there would silently skip this job.
-    # base_python_changed is deliberately broad (any top-level esphome/*.py)
-    # as belt-and-braces while the backend is new; narrow it to the modules
-    # the backend imports once the toolchain has soaked a few releases
-    return base_python_changed(files) or _path_or_file_trigger(
-        files, ESP8266_NATIVE_TRIGGER_FILES, ESP8266_NATIVE_TRIGGER_PATH_PREFIXES
-    )
-
-
-def esp8266_native_components_to_test(branch: str | None = None) -> list[str]:
-    """Subset of ``ESP8266_NATIVE_TEST_COMPONENTS`` the job needs to compile.
-
-    Same narrowing logic as ``esp32_platformio_components_to_test``: the full
-    list on core or infrastructure changes, otherwise the intersection with
-    the changed-component dependency closure (empty list skips the job).
-    """
-    return _toolchain_components_to_test(
-        branch, ESP8266_NATIVE_TEST_COMPONENTS, _esp8266_native_path_or_file_trigger
-    )
-
-
 def determine_cpp_unit_tests(
    branch: str | None = None,
 ) -> tuple[bool, list[str]]:
@@ -1328,8 +1226,6 @@ def main() -> None:
        run_device_builder = True
        esp32_platformio_components = sorted(ESP32_PLATFORMIO_TEST_COMPONENTS)
        run_esp32_platformio = True
-        esp8266_native_components = sorted(ESP8266_NATIVE_TEST_COMPONENTS)
-        run_esp8266_native = True
    else:
        integration_run_all, integration_test_files = determine_integration_tests(
            args.branch
@@ -1341,8 +1237,6 @@ def main() -> None:
        run_device_builder = should_run_device_builder(args.branch)
        esp32_platformio_components = esp32_platformio_components_to_test(args.branch)
        run_esp32_platformio = bool(esp32_platformio_components)
-        esp8266_native_components = esp8266_native_components_to_test(args.branch)
-        run_esp8266_native = bool(esp8266_native_components)
    run_integration, integration_test_buckets = _compute_integration_test_buckets(
        integration_run_all, integration_test_files
    )
@@ -1538,8 +1432,6 @@ def main() -> None:
        "device_builder": run_device_builder,
        "esp32_platformio": run_esp32_platformio,
        "esp32_platformio_components": ",".join(esp32_platformio_components),
-        "esp8266_native": run_esp8266_native,
-        "esp8266_native_components": ",".join(esp8266_native_components),
        "changed_components": changed_components,
        "changed_components_with_tests": changed_components_with_tests,
        "directly_changed_components_with_tests": list(directly_changed_with_tests),
@@ -1104,6 +1104,10 @@ def get_components_per_integration_fixture() -> dict[str, set[str]]:


 _TEST_FUNC_RE = re.compile(r"async def (test_\w+)")
+# Any usage form (decorator, pytestmark assignment or list element); only
+# test_*.py files are scanned, so the marker docs elsewhere cannot false-hit
+_SHARED_YAML_USE_RE = re.compile(r"\bmark\.shared_yaml")
+_SHARED_YAML_ARG_RE = re.compile(r"\(\s*[\"'](\w+)[\"']\s*\)")


@cache
@@ -1123,6 +1127,19 @@ def get_fixture_to_test_files() -> dict[str, frozenset[str]]:
        for func in _TEST_FUNC_RE.findall(content):
            base_name = func.replace("test_", "").partition("[")[0]
            result.setdefault(base_name, set()).add(rel_path)
+        # Shared fixtures are named by marker, not by a test function; each
+        # decorator must carry a string literal or its fixture would silently
+        # map to no tests
+        for use in _SHARED_YAML_USE_RE.finditer(content):
+            arg = _SHARED_YAML_ARG_RE.match(content, use.end())
+            if arg is None:
+                line = content.count("\n", 0, use.start()) + 1
+                raise ValueError(
+                    f"{rel_path}:{line}: shared_yaml marker must take a "
+                    "single-line string literal so CI test selection can map "
+                    "its fixture"
+                )
+            result.setdefault(arg.group(1), set()).add(rel_path)

    return {k: frozenset(v) for k, v in result.items()}

@@ -1027,7 +1027,6 @@ def test_components(
    isolated_components: set[str] | None = None,
    base_only: bool = False,
    toolchain: str | None = None,
-    fail_on_no_tests: bool = False,
 ) -> int:
    """Test components with optional intelligent grouping.

@@ -1062,34 +1061,20 @@ def test_components(
    # toolchain build.
    include_validate = esphome_command != "compile"

-    # Find all component tests; remember which components each pattern
-    # (wildcards included) matched, for the deferred no-tests accounting
+    # Find all component tests
    all_tests = {}
-    pattern_components: dict[str, set[str]] = {}
    for pattern in component_patterns:
        # Skip empty patterns (happens when components list is empty string)
        if not pattern:
            continue
-        found = find_component_tests(
-            tests_dir, pattern, base_only, include_validate=include_validate
+        all_tests.update(
+            find_component_tests(
+                tests_dir, pattern, base_only, include_validate=include_validate
+            )
        )
-        pattern_components[pattern] = set(found)
-        all_tests.update(found)
-
-    # The flag's contract is "no test matched fails": a fully blank pattern
-    # list would otherwise slide into the reference-baseline fallback and
-    # exit green while building nothing a caller asked for
-    if fail_on_no_tests and not any(component_patterns):
-        print("No components requested (blank component list)")
-        return 1
-
-    if fail_on_no_tests and not all_tests:
-        # Nothing matched at all: fail before the synthetic baseline build,
-        # which would spend a compile reporting success on nothing. Partial
-        # matches defer to the per-pattern accounting after the summary.
-        print(f"No components found matching: {component_patterns}")
-        return 1

+    # If no components found, build a reference configuration for baseline comparison
+    # Create a synthetic "empty" component test that will build just the base config
    if not all_tests:
        print(f"No components found matching: {component_patterns}")
        print(
@@ -1193,26 +1178,6 @@ def test_components(
                        toolchain=toolchain,
                    )

-    silent: list[str] = []
-    if fail_on_no_tests:
-        # A green run that built nothing for a requested pattern (renamed
-        # fixture, missing base file, version-suffix mismatch, a wildcard
-        # matching no component) must not pass CI. Per pattern: an
-        # all-or-nothing check would let one silent pattern hide behind the
-        # others. Opt-in: some legs (the esp32-ard smoke subset)
-        # legitimately match nothing. Failing is deferred past the summary
-        # so a real failure's reproduce commands still print.
-        built = {c for r in test_results for c in r.components}
-        # A pattern is silent when it matched no fixture, or when none of
-        # its matched components produced a build (wildcards included)
-        silent = [
-            p
-            for p in component_patterns
-            if p and not (pattern_components.get(p, set()) & built)
-        ]
-        if silent:
-            print(f"No tests ran for requested pattern(s): {', '.join(silent)}")
-
    # Separate results into passed and failed
    passed_results = [r for r in test_results if r.success]
    failed_results = [r for r in test_results if not r.success]
@@ -1244,7 +1209,7 @@ def test_components(
    if os.environ.get("GITHUB_STEP_SUMMARY"):
        write_github_summary(test_results, toolchain=toolchain)

-    if failed_results or silent:
+    if failed_results:
        return 1

    return 0
@@ -1299,12 +1264,6 @@ def main() -> int:
        "--toolchain",
        help="Select toolchain for compiling.",
    )
-    parser.add_argument(
-        "--fail-on-no-tests",
-        action="store_true",
-        help="Exit non-zero when no test matched (for CI legs whose "
-        "components must all have fixtures)",
-    )

    args = parser.parse_args()

@@ -1323,7 +1282,6 @@ def main() -> int:
        continue_on_fail=args.continue_on_fail,
        enable_grouping=not args.no_grouping,
        isolated_components=isolated_components,
-        fail_on_no_tests=args.fail_on_no_tests,
        base_only=args.base_only,
        toolchain=args.toolchain,
    )
@@ -0,0 +1,148 @@
+"""Tests for the api outgoing_connection option."""
+
+from collections.abc import Callable
+from pathlib import Path
+
+import pytest
+
+from esphome.components import socket
+from esphome.components.api import (
+    CONFIG_SCHEMA,
+    _validate_outgoing_host_ipv6,
+    _validate_outgoing_socket_implementation,
+)
+from esphome.components.esp32 import KEY_BOARD, KEY_VARIANT, VARIANT_ESP32
+import esphome.config_validation as cv
+from esphome.const import PlatformFramework
+from esphome.core import CORE
+import esphome.final_validate as fv
+from esphome.types import ConfigType
+from tests.component_tests.types import SetCoreConfigCallable
+
+KEY = "bOFFzzvfpg5DB94DuBGLXD/hMnhpDKgP9UQyBulwWVU="
+ESP32_PLATFORM_DATA = {KEY_BOARD: "esp32dev", KEY_VARIANT: VARIANT_ESP32}
+
+
+def _api_config(outgoing: ConfigType, *, encryption: bool = True) -> ConfigType:
+    config: ConfigType = {"outgoing_connection": outgoing}
+    if encryption:
+        config["encryption"] = {"key": KEY}
+    return config
+
+
+def test_outgoing_connection_generates_defines(
+    generate_main: Callable[[str | Path], str],
+) -> None:
+    """A valid config emits the compile-time defines with defaults applied."""
+    generate_main("tests/component_tests/api/test_outgoing_connection.yaml")
+
+    defines = {define.name: define.value for define in CORE.defines}
+    assert "USE_API_OUTGOING_CONNECTION" in defines
+    assert str(defines["API_OUTGOING_CONNECTION_HOST"]) == '"192.168.1.2"'
+    assert str(defines["API_OUTGOING_CONNECTION_PORT"]) == "6054"
+    assert str(defines["API_OUTGOING_CONNECTION_DELAY"]) == "60000"
+
+
+def test_outgoing_connection_defaults(
+    set_core_config: SetCoreConfigCallable,
+) -> None:
+    set_core_config(PlatformFramework.ESP32_IDF, platform_data=ESP32_PLATFORM_DATA)
+    config = CONFIG_SCHEMA(_api_config({"host": "192.168.1.2"}))
+    outgoing = config["outgoing_connection"]
+    assert outgoing["port"] == 6054
+    assert outgoing["delay"].total_milliseconds == 60000
+
+
+def test_outgoing_connection_bare_block(
+    set_core_config: SetCoreConfigCallable,
+) -> None:
+    """A bare outgoing_connection: block is valid; the device dials the
+    remembered last dial-back client."""
+    set_core_config(PlatformFramework.ESP32_IDF, platform_data=ESP32_PLATFORM_DATA)
+    config = CONFIG_SCHEMA(_api_config(None))
+    outgoing = config["outgoing_connection"]
+    assert "host" not in outgoing
+    assert outgoing["port"] == 6054
+
+
+def test_outgoing_connection_delay_bounded(
+    set_core_config: SetCoreConfigCallable,
+) -> None:
+    """A delay past half the uint32 millisecond range is rejected, not wrapped."""
+    set_core_config(PlatformFramework.ESP32_IDF, platform_data=ESP32_PLATFORM_DATA)
+    with pytest.raises(cv.Invalid, match="value must be at most"):
+        CONFIG_SCHEMA(_api_config({"delay": "60d"}))
+
+
+def test_outgoing_connection_requires_encryption(
+    set_core_config: SetCoreConfigCallable,
+) -> None:
+    set_core_config(PlatformFramework.ESP32_IDF, platform_data=ESP32_PLATFORM_DATA)
+    with pytest.raises(cv.Invalid, match="requires 'encryption'"):
+        CONFIG_SCHEMA(_api_config({"host": "192.168.1.2"}, encryption=False))
+
+
+@pytest.mark.parametrize(
+    ("platform_framework", "platform_data", "socket_conf"),
+    [
+        # The platform default on these two, resolved like AUTO_LOAD does
+        (PlatformFramework.ESP8266_ARDUINO, None, None),
+        (PlatformFramework.RP2040_ARDUINO, None, None),
+        # An explicit selection elsewhere
+        (
+            PlatformFramework.ESP32_IDF,
+            ESP32_PLATFORM_DATA,
+            {"implementation": "lwip_tcp"},
+        ),
+    ],
+)
+def test_outgoing_connection_rejects_lwip_tcp(
+    set_core_config: SetCoreConfigCallable,
+    platform_framework: PlatformFramework,
+    platform_data: ConfigType | None,
+    socket_conf: ConfigType | None,
+) -> None:
+    """The resolved lwip_tcp socket is rejected at final validate."""
+    set_core_config(platform_framework, platform_data=platform_data)
+    fv.full_config.set({"socket": socket_conf or socket.CONFIG_SCHEMA({})})
+    config = CONFIG_SCHEMA(_api_config({"host": "192.168.1.2"}))
+    with pytest.raises(cv.Invalid, match="lwip_tcp"):
+        _validate_outgoing_socket_implementation(config)
+
+
+def test_outgoing_connection_rejects_hostnames(
+    set_core_config: SetCoreConfigCallable,
+) -> None:
+    set_core_config(PlatformFramework.ESP32_IDF, platform_data=ESP32_PLATFORM_DATA)
+    with pytest.raises(cv.Invalid, match="not a valid IP address"):
+        CONFIG_SCHEMA(_api_config({"host": "homeassistant.local"}))
+
+
+def test_outgoing_connection_ipv6_host_requires_ipv6(
+    set_core_config: SetCoreConfigCallable,
+) -> None:
+    set_core_config(PlatformFramework.ESP32_IDF, platform_data=ESP32_PLATFORM_DATA)
+    config = CONFIG_SCHEMA(_api_config({"host": "fd00::1"}))
+    with pytest.raises(cv.Invalid, match="IPv6 is not"):
+        _validate_outgoing_host_ipv6(config)
+
+
+def test_outgoing_connection_ipv6_host_passes_with_ipv6_enabled(
+    set_core_config: SetCoreConfigCallable,
+) -> None:
+    set_core_config(
+        PlatformFramework.ESP32_IDF,
+        platform_data=ESP32_PLATFORM_DATA,
+        full_config={"network": {"enable_ipv6": True}},
+    )
+    config = CONFIG_SCHEMA(_api_config({"host": "fd00::1"}))
+    assert _validate_outgoing_host_ipv6(config) is config
+
+
+def test_outgoing_connection_ipv6_host_with_ipv6(
+    generate_main: Callable[[str | Path], str],
+) -> None:
+    generate_main("tests/component_tests/api/test_outgoing_connection_ipv6.yaml")
+
+    defines = {define.name: define.value for define in CORE.defines}
+    assert str(defines["API_OUTGOING_CONNECTION_HOST"]) == '"fd00::1"'
@@ -0,0 +1,17 @@
+esphome:
+  name: test
+
+esp32:
+  board: esp32dev
+
+wifi:
+  ssid: SomeNetwork
+  password: SomePassword
+
+logger:
+
+api:
+  encryption:
+    key: bOFFzzvfpg5DB94DuBGLXD/hMnhpDKgP9UQyBulwWVU=
+  outgoing_connection:
+    host: 192.168.1.2
@@ -0,0 +1,20 @@
+esphome:
+  name: test
+
+esp32:
+  board: esp32dev
+
+wifi:
+  ssid: SomeNetwork
+  password: SomePassword
+
+network:
+  enable_ipv6: true
+
+logger:
+
+api:
+  encryption:
+    key: bOFFzzvfpg5DB94DuBGLXD/hMnhpDKgP9UQyBulwWVU=
+  outgoing_connection:
+    host: fd00::1
@@ -0,0 +1,13 @@
+packages:
+  common: !include common-base.yaml
+
+wifi:
+  ssid: MySSID
+  password: password1
+
+# Outgoing connection on the lwip_sockets implementation used by LibreTiny
+api:
+  encryption:
+    key: bOFFzzvfpg5DB94DuBGLXD/hMnhpDKgP9UQyBulwWVU=
+  outgoing_connection:
+    host: 192.168.1.2
@@ -0,0 +1,16 @@
+packages:
+  common: !include common-base.yaml
+
+wifi:
+  ssid: MySSID
+  password: password1
+
+# Outgoing connection: the device dials out when no dial-back client is
+# connected. Requires encryption so the peer is verified by key.
+api:
+  encryption:
+    key: bOFFzzvfpg5DB94DuBGLXD/hMnhpDKgP9UQyBulwWVU=
+  outgoing_connection:
+    host: 192.168.1.2
+    port: 6054
+    delay: 60s
@@ -0,0 +1,11 @@
+packages:
+  common: !include common-base.yaml
+
+network:
+
+# No host set: the device dials the last remembered Home Assistant address
+api:
+  encryption:
+    key: bOFFzzvfpg5DB94DuBGLXD/hMnhpDKgP9UQyBulwWVU=
+  outgoing_connection:
+    delay: 30s
@@ -21,6 +21,13 @@ The `yaml_config` fixture automatically loads YAML configurations based on the t
 - The fixture file must exist or the test will fail with a clear error message
 - The fixture automatically injects a dynamic port number into the API configuration

+Tests marked `@pytest.mark.shared_yaml("name")` load `fixtures/name.yaml` instead
+of the test-named file and compile it in a shared, hash-keyed build directory, so
+the whole group pays one full compile and each test only a relink. The marker
+argument must be a single-line string literal (CI test selection maps fixtures to
+test files by scanning for it), and marked tests must hand the `yaml_config`
+content to `run_compiled` unmodified.
+
 ### Key Fixtures

 - `run_compiled` - Combines write, compile, and run operations into a single context manager
@@ -4,17 +4,22 @@ from __future__ import annotations

 import asyncio
 from collections.abc import AsyncGenerator, Callable, Generator
-from contextlib import AbstractAsyncContextManager, asynccontextmanager
+from contextlib import AbstractAsyncContextManager, asynccontextmanager, suppress
 import fcntl
+from functools import cache
+import hashlib
 import logging
 import os
 from pathlib import Path
 import platform
+import re
+import shutil
 import signal
 import socket
 import subprocess
 import sys
 import tempfile
+import time
 from typing import TextIO

 from aioesphomeapi import APIClient, APIConnectionError, LogParser, ReconnectLogic
@@ -23,7 +28,13 @@ import pytest_asyncio

 import esphome.config
 from esphome.core import CORE
-from esphome.helpers import get_usable_cpu_count
+from esphome.helpers import (
+    get_usable_cpu_count,
+    read_file,
+    rmtree,
+    write_file,
+    write_file_if_changed,
+)
 from esphome.platformio.toolchain import get_idedata

 from .const import (
@@ -56,6 +67,21 @@ import pty  # not available on Windows
 pytest.register_assert_rewrite("tests.integration.entity_utils")


+def pytest_configure(config: pytest.Config) -> None:
+    config.addinivalue_line(
+        "markers",
+        "shared_yaml(name): load fixtures/<name>.yaml and compile it in a shared, "
+        "hash-keyed incremental build directory",
+    )
+
+
+FIXTURES_DIR = Path(__file__).parent / "fixtures"
+REPO_ROOT = Path(__file__).resolve().parent.parent.parent
+
+# CI caches parts of this path; keep in sync with ci.yml integration-tests.
+INTEGRATION_TESTS_ROOT = Path.home() / ".esphome-integration-tests"
+
+
 def _get_platformio_env(cache_dir: Path) -> dict[str, str]:
    """Get environment variables for PlatformIO with shared cache."""
    env = os.environ.copy()
@@ -78,7 +104,7 @@ def _get_platformio_env(cache_dir: Path) -> dict[str, str]:
        )
    # Compile with THIS tree's esphome sources, not wherever the venv's editable
    # install points (which may be a different git worktree or checkout).
-    repo_root = str(Path(__file__).resolve().parent.parent.parent)
+    repo_root = str(REPO_ROOT)
    existing = env.get("PYTHONPATH")
    env["PYTHONPATH"] = f"{repo_root}{os.pathsep}{existing}" if existing else repo_root
    return env
@@ -88,8 +114,7 @@ def _get_platformio_env(cache_dir: Path) -> dict[str, str]:
 def shared_platformio_cache() -> Generator[Path]:
    """Initialize a shared PlatformIO cache for all integration tests."""
    # Use a dedicated directory for integration tests to avoid conflicts.
-    # CI caches parts of this path; keep in sync with ci.yml integration-tests.
-    test_cache_dir = Path.home() / ".esphome-integration-tests"
+    test_cache_dir = INTEGRATION_TESTS_ROOT
    cache_dir = test_cache_dir / "platformio"

    # Use a lock file in the home directory to ensure only one process initializes the cache
@@ -112,7 +137,9 @@ def shared_platformio_cache() -> Generator[Path]:
                init_dir = Path(tmpdir)
                fixture_path = Path(__file__).parent / "fixtures" / "cache_init.yaml"
                config_path = init_dir / "cache_init.yaml"
-                config_path.write_text(fixture_path.read_text())
+                config_path.write_text(
+                    fixture_path.read_text(encoding="utf-8"), encoding="utf-8"
+                )

                # Run compilation to populate the cache
                # We must succeed here to avoid race conditions where multiple
@@ -162,13 +189,6 @@ def integration_test_dir() -> Generator[Path]:
        yield Path(tmpdir)


-@pytest.fixture
-def isolated_preferences(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> None:
-    """Host preferences persist per device name; give the test its own so a
-    provisioned key never leaks into another run."""
-    monkeypatch.setenv("ESPHOME_PREFDIR", str(tmp_path / "prefs"))
-
-
@pytest.fixture
 def reserved_tcp_port() -> Generator[tuple[int, socket.socket]]:
    """Reserve an unused TCP port by holding the socket open."""
@@ -188,21 +208,29 @@ def unused_tcp_port(reserved_tcp_port: tuple[int, socket.socket]) -> int:
    return reserved_tcp_port[0]


+@pytest.fixture(autouse=True)
+def isolated_preferences(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> Path:
+    """Give every test its own host prefs dir; prefs are keyed only by device
+    name, which tests sharing a fixture also share."""
+    prefdir = tmp_path / "prefs"
+    monkeypatch.setenv("ESPHOME_PREFDIR", str(prefdir))
+    return prefdir
+
+
@pytest_asyncio.fixture
 async def yaml_config(request: pytest.FixtureRequest, unused_tcp_port: int) -> str:
    """Load YAML configuration based on test name."""
-    # Get the test function name
-    test_name: str = request.node.name
-    # Extract the base test name (remove test_ prefix and any parametrization)
-    base_name = test_name.replace("test_", "").partition("[")[0]
+    shared_name = _shared_yaml_name(request)
+    # Base test name: test_ prefix and any parametrization stripped
+    base_name = shared_name or request.node.name.replace("test_", "").partition("[")[0]

    # Load the fixture file
-    fixture_path = Path(__file__).parent / "fixtures" / f"{base_name}.yaml"
+    fixture_path = FIXTURES_DIR / f"{base_name}.yaml"
    if not fixture_path.exists():
        raise FileNotFoundError(f"Fixture file not found: {fixture_path}")

    loop = asyncio.get_running_loop()
-    content = await loop.run_in_executor(None, fixture_path.read_text)
+    content = await loop.run_in_executor(None, read_file, fixture_path)

    # Replace the port in the config if it contains api section
    if "api:" in content:
@@ -226,11 +254,13 @@ async def yaml_config(request: pytest.FixtureRequest, unused_tcp_port: int) -> s

    # Replace external component path placeholder if present
    if "EXTERNAL_COMPONENT_PATH" in content:
-        external_components_path = str(
-            Path(__file__).parent / "fixtures" / "external_components"
-        )
+        external_components_path = str(FIXTURES_DIR / "external_components")
        content = content.replace("EXTERNAL_COMPONENT_PATH", external_components_path)

+    if shared_name is not None:
+        # _compile verifies the marked test compiles this content unmodified
+        request.node._shared_yaml_content = content
+
    return content


@@ -240,24 +270,218 @@ async def write_yaml_config(
 ) -> AsyncGenerator[ConfigWriter]:
    """Write YAML configuration to a file."""
    # Get the test name for default filename
-    test_name = request.node.name
-    base_name = test_name.replace("test_", "").split("[")[0]
+    base_name = request.node.name.replace("test_", "").partition("[")[0]

    async def _write_config(content: str, filename: str | None = None) -> Path:
        if filename is None:
            filename = f"{base_name}.yaml"
        config_path = integration_test_dir / filename
        loop = asyncio.get_running_loop()
-        await loop.run_in_executor(None, config_path.write_text, content)
+        await loop.run_in_executor(None, write_file, config_path, content)
        return config_path

    yield _write_config


+# Deliberately not CI-cached (ci.yml caches only platformio/ subpaths); stale
+# dirs for a fixture are pruned when its content hash changes.
+SHARED_BUILDS_ROOT = INTEGRATION_TESTS_ROOT / "builds"
+
+# In the dir name (not just the hash) so pruning stays inside this checkout
+_REPO_KEY = hashlib.sha256(str(REPO_ROOT).encode()).hexdigest()[:8]
+
+# Give a contended shared build lock time for a full cold compile ahead of us
+_SHARED_LOCK_TIMEOUT_S = 900
+_SHARED_LOCK_POLL_S = 0.1
+_SHARED_LOCK_REPORT_S = 30
+
+# Reclaims dirs orphaned by fixture renames or deleted checkouts
+_STALE_BUILD_MAX_AGE_S = 30 * 24 * 3600
+
+# ELF path per shared build dir; constant once compiled, so resolve it only once
+_shared_elf_paths: dict[Path, Path] = {}
+
+# Dirs this process already swept; pruning is session-scoped work
+_pruned_dirs: set[Path] = set()
+
+
+def _shared_yaml_name(request: pytest.FixtureRequest) -> str | None:
+    """Name passed to the shared_yaml marker, or None when unmarked."""
+    marker = request.node.get_closest_marker("shared_yaml")
+    if marker is None:
+        return None
+    # Exactly one \w+ positional arg: the name doubles as a build dir
+    # component, and CI test selection (script/helpers.py) parses the same shape
+    if (
+        len(marker.args) != 1
+        or marker.kwargs
+        or not re.fullmatch(r"\w+", str(marker.args[0]))
+    ):
+        raise ValueError(
+            "shared_yaml marker requires exactly one \\w+ fixture name literal"
+        )
+    return marker.args[0]
+
+
+def _shared_build_prefix(name: str) -> str:
+    return f"{name}-{_REPO_KEY}-"
+
+
+@cache
+def _shared_build_dir(name: str) -> Path:
+    """Dir keyed by checkout and fixture source, before per-test injections."""
+    key = hashlib.sha256((FIXTURES_DIR / f"{name}.yaml").read_bytes()).hexdigest()[:16]
+    return SHARED_BUILDS_ROOT / (_shared_build_prefix(name) + key)
+
+
+def _read_stamp(stamp: Path, shared_dir: Path) -> Path | None:
+    """ELF path recorded by the last completed compile, or None."""
+    try:
+        text = stamp.read_text(encoding="utf-8").strip()
+    except FileNotFoundError:
+        return None
+    except OSError as err:
+        print(f"Cannot read {stamp}: {err}")
+        return None
+    if not text:
+        print(f"Ignoring empty stamp {stamp}")
+        return None
+    built = Path(text)
+    # Never trust a stamp pointing outside its own build dir as an unlink target
+    if shared_dir.resolve() in built.resolve().parents:
+        return built
+    print(f"Ignoring stamp {stamp} pointing outside {shared_dir}")
+    return None
+
+
+def _unused_since(stale: Path, cutoff: float) -> bool:
+    """Whether a build dir looks untouched since cutoff; unknown counts as used."""
+    # Newest of the .built stamp (rewritten by every completed compile) and the
+    # dir itself (freshened by a worker claiming the dir before locking)
+    newest: float | None = None
+    for probe in (stale / ".built", stale):
+        try:
+            mtime = probe.stat().st_mtime
+        except FileNotFoundError:
+            continue
+        except NotADirectoryError:
+            return True  # a stray file where a dir should be; reclaimable
+        except OSError as err:
+            print(f"Cannot age-probe {stale}: {err}")
+            return False  # unknown never authorizes deletion
+        newest = mtime if newest is None else max(newest, mtime)
+    return newest is not None and newest < cutoff
+
+
+def _prune_stale_builds(name: str, keep: Path) -> None:
+    """Remove outdated build dirs (blocking, run in executor): this checkout's
+    other dirs for the fixture, plus anything untouched for 30 days. Tolerates
+    other workers pruning the same dirs concurrently."""
+    cutoff = time.time() - _STALE_BUILD_MAX_AGE_S
+    prefix = _shared_build_prefix(name)
+    for stale in SHARED_BUILDS_ROOT.iterdir():
+        if stale == keep:
+            continue
+        same_fixture = stale.name.startswith(prefix)
+        if not same_fixture and not _unused_since(stale, cutoff):
+            continue
+        # Creating .lock bumps the dir mtime, so remember whether the re-probe
+        # under the lock can trust it
+        lock_preexisting = (stale / ".lock").exists()
+        try:
+            lock_file = (stale / ".lock").open("w")
+        except FileNotFoundError:
+            continue  # pruned by another worker meanwhile
+        except NotADirectoryError:
+            print(f"Removing stray file {stale}")
+            stale.unlink(missing_ok=True)
+            continue
+        except OSError as err:
+            print(f"Cannot prune {stale}: {err}")
+            continue
+        with lock_file:
+            try:
+                fcntl.flock(lock_file.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
+            except BlockingIOError:
+                continue  # still in use by another run
+            # Re-probe under the lock: a worker freshens its dir before
+            # locking, so a just-claimed dir no longer looks unused. A dir
+            # whose .lock we just created cannot be held by anyone, and our
+            # own open bumped its mtime, so its pre-open probe stands
+            if (
+                lock_preexisting
+                and not same_fixture
+                and not _unused_since(stale, cutoff)
+            ):
+                continue
+            # rmtree tolerates races; a leftover partial tree only costs a
+            # rebuild, since the ELF is deleted before every compile
+            try:
+                rmtree(stale)
+            except OSError as err:
+                print(f"Failed to prune {stale}: {err}")
+
+
+async def _run_esphome_compile(
+    config_path: Path, cwd: Path, env: dict[str, str]
+) -> None:
+    """Run `esphome compile`, retrying up to 3 times on a segfault."""
+    max_retries = 3
+    for attempt in range(max_retries):
+        # Compile using subprocess, inheriting stdout/stderr to show progress
+        proc = await asyncio.create_subprocess_exec(
+            sys.executable,
+            "-m",
+            "esphome",
+            "compile",
+            str(config_path),
+            cwd=cwd,
+            stdout=None,  # Inherit stdout
+            stderr=None,  # Inherit stderr
+            stdin=asyncio.subprocess.DEVNULL,
+            # Start in a new process group to isolate signal handling
+            start_new_session=True,
+            env=env,
+            close_fds=False,
+        )
+        await proc.wait()
+
+        if proc.returncode == 0:
+            break
+        if proc.returncode == -11 and attempt < max_retries - 1:
+            # Segfault (-11 = SIGSEGV), retry
+            print(
+                f"Compilation segfaulted (attempt {attempt + 1}/{max_retries}), retrying..."
+            )
+            await asyncio.sleep(1)  # Brief pause before retry
+            continue
+        raise RuntimeError(
+            f"Failed to compile {config_path}, return code: {proc.returncode}. "
+            f"Run with 'pytest -s' to see compilation output."
+        )
+
+
+def _resolve_compiled_binary(config_path: Path) -> Path:
+    """Load the config to learn the compiled ELF path (blocking, run in executor)."""
+    CORE.reset()  # Reset CORE state between test runs
+    CORE.config_path = config_path
+    config = esphome.config.read_config(
+        {"command": "compile", "config": str(config_path)}
+    )
+    if config is None:
+        raise RuntimeError(f"Failed to read config from {config_path}")
+    idedata = get_idedata(config)
+    binary_path = Path(idedata.firmware_elf_path)
+    if not binary_path.exists():
+        raise RuntimeError(f"Compiled binary not found at {binary_path}")
+    return binary_path
+
+
@pytest_asyncio.fixture
 async def compile_esphome(
    integration_test_dir: Path,
    shared_platformio_cache: Path,
+    request: pytest.FixtureRequest,
 ) -> AsyncGenerator[CompileFunction]:
    """Compile an ESPHome configuration and return the binary path."""

@@ -265,66 +489,96 @@ async def compile_esphome(
        # Use the shared PlatformIO cache for faster compilation
        # This avoids re-downloading dependencies for each test
        env = _get_platformio_env(shared_platformio_cache)
-
-        # Retry compilation up to 3 times if we get a segfault
-        max_retries = 3
-        for attempt in range(max_retries):
-            # Compile using subprocess, inheriting stdout/stderr to show progress
-            proc = await asyncio.create_subprocess_exec(
-                sys.executable,
-                "-m",
-                "esphome",
-                "compile",
-                str(config_path),
-                cwd=integration_test_dir,
-                stdout=None,  # Inherit stdout
-                stderr=None,  # Inherit stderr
-                stdin=asyncio.subprocess.DEVNULL,
-                # Start in a new process group to isolate signal handling
-                start_new_session=True,
-                env=env,
-                close_fds=False,
-            )
-            await proc.wait()
-
-            if proc.returncode == 0:
-                # Success!
-                break
-            if proc.returncode == -11 and attempt < max_retries - 1:
-                # Segfault (-11 = SIGSEGV), retry
-                print(
-                    f"Compilation segfaulted (attempt {attempt + 1}/{max_retries}), retrying..."
-                )
-                await asyncio.sleep(1)  # Brief pause before retry
-                continue
-            # Other error or final retry
-            raise RuntimeError(
-                f"Failed to compile {config_path}, return code: {proc.returncode}. "
-                f"Run with 'pytest -s' to see compilation output."
-            )
-
-        # Load the config to get idedata (blocking call, must use executor)
        loop = asyncio.get_running_loop()

-        def _read_config_and_get_binary():
-            CORE.reset()  # Reset CORE state between test runs
-            CORE.config_path = config_path
-            config = esphome.config.read_config(
-                {"command": "compile", "config": str(config_path)}
+        name = _shared_yaml_name(request)
+        if name is None:
+            await _run_esphome_compile(config_path, integration_test_dir, env)
+            return await loop.run_in_executor(
+                None, _resolve_compiled_binary, config_path
            )
-            if config is None:
-                raise RuntimeError(f"Failed to read config from {config_path}")

-            # Get the compiled binary path
-            idedata = get_idedata(config)
-            return Path(idedata.firmware_elf_path)
-
-        binary_path = await loop.run_in_executor(None, _read_config_and_get_binary)
-
-        if not binary_path.exists():
-            raise RuntimeError(f"Compiled binary not found at {binary_path}")
-
-        return binary_path
+        # Shared fixture: build in a hash-keyed dir so tests sharing a config
+        # pay one full compile and later only a main.cpp (port) rebuild + relink
+        shared_dir = _shared_build_dir(name)
+        shared_dir.mkdir(parents=True, exist_ok=True)
+        # Freshen the dir before locking so a concurrent age sweep, which
+        # re-probes under the lock, never reaps a dir a worker just claimed;
+        # if a peer reaped it already, the guarded lock open recreates it
+        with suppress(FileNotFoundError):
+            os.utime(shared_dir)
+        if shared_dir not in _pruned_dirs:
+            _pruned_dirs.add(shared_dir)
+            await loop.run_in_executor(None, _prune_stale_builds, name, shared_dir)
+        shared_config = shared_dir / f"{name}.yaml"
+        private_binary = integration_test_dir / f"{name}.elf"
+        content = await loop.run_in_executor(None, read_file, config_path)
+        if content != getattr(request.node, "_shared_yaml_content", None):
+            # The dir is keyed by the fixture source; a mutated config would be
+            # cached under a hash that does not describe it
+            raise RuntimeError(
+                "shared_yaml tests must compile the yaml_config content unmodified"
+            )
+        # flock serializes concurrent xdist workers; closing the fd releases it.
+        # Hand-rolled rather than filelock.FileLock: non-blocking retries keep
+        # the wait cancellable, while a blocking acquire in an executor thread
+        # would survive test cancellation holding the fd
+        try:
+            lock_file = (shared_dir / ".lock").open("w")
+        except FileNotFoundError:
+            # A peer run pruning divergent hashes reaped the dir between our
+            # mkdir and this open; recreate it and pay a full rebuild
+            shared_dir.mkdir(parents=True, exist_ok=True)
+            lock_file = (shared_dir / ".lock").open("w")
+        with lock_file:
+            start = time.monotonic()
+            last_report = start
+            while True:
+                try:
+                    fcntl.flock(lock_file.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
+                    break
+                except BlockingIOError:
+                    now = time.monotonic()
+                    if now - start > _SHARED_LOCK_TIMEOUT_S:
+                        raise RuntimeError(
+                            f"Timed out waiting for the {shared_dir} lock"
+                        ) from None
+                    if now - last_report >= _SHARED_LOCK_REPORT_S:
+                        last_report = now
+                        print(
+                            f"Waited {now - start:.0f}s for another worker's "
+                            f"build of {shared_dir.name}"
+                        )
+                    await asyncio.sleep(_SHARED_LOCK_POLL_S)
+            # .built carries the ELF path of the last completed compile, so
+            # later workers skip the config re-read in _resolve_compiled_binary
+            stamp = shared_dir / ".built"
+            if (built := _shared_elf_paths.get(shared_dir)) is None:
+                built = await loop.run_in_executor(None, _read_stamp, stamp, shared_dir)
+            # Delete the ELF before compiling: whatever exists afterwards is
+            # this compile's output, so no staleness check is ever needed.
+            # With no usable stamp, sweep any leftover at the known layout
+            if built is not None:
+                built.unlink(missing_ok=True)
+            else:
+                # Layout-agnostic: ESPHOME_BUILD_PATH can move the build tree
+                for leftover in shared_dir.rglob("program"):
+                    if leftover.is_file():
+                        leftover.unlink()
+            await loop.run_in_executor(
+                None, write_file_if_changed, shared_config, content
+            )
+            await _run_esphome_compile(shared_config, shared_dir, env)
+            if built is None or not built.exists():
+                built = await loop.run_in_executor(
+                    None, _resolve_compiled_binary, shared_config
+                )
+            _shared_elf_paths[shared_dir] = built
+            await loop.run_in_executor(None, write_file, stamp, str(built))
+            # Copy out before unlocking: another worker may relink firmware.elf
+            # while this test is still running its private copy
+            await loop.run_in_executor(None, shutil.copy2, built, private_binary)
+        return private_binary

    yield _compile

@@ -0,0 +1,14 @@
+esphome:
+  name: outgoing-conn-test
+
+host:
+
+logger:
+
+api:
+  encryption:
+    key: bOFFzzvfpg5DB94DuBGLXD/hMnhpDKgP9UQyBulwWVU=
+  outgoing_connection:
+    host: 127.0.0.1
+    port: OUTGOING_PORT
+    delay: 1s
@@ -0,0 +1,13 @@
+esphome:
+  name: outgoing-conn-test
+
+host:
+
+logger:
+
+api:
+  encryption:
+    key: bOFFzzvfpg5DB94DuBGLXD/hMnhpDKgP9UQyBulwWVU=
+  outgoing_connection:
+    port: OUTGOING_PORT
+    delay: 1s
@@ -0,0 +1,7 @@
+esphome:
+  name: api-reboot-test
+host:
+api:
+  reboot_timeout: 2s  # Headroom to connect and authenticate a client first
+logger:
+  level: DEBUG
@@ -1,58 +0,0 @@
-esphome:
-  name: test-batch-window-filters
-
-host:
-api:
-  batch_delay: 0ms  # Disable batching to receive all state updates
-logger:
-  level: DEBUG
-
-# Template sensor that we'll use to publish values
-sensor:
-  - platform: template
-    name: "Source Sensor"
-    id: source_sensor
-    accuracy_decimals: 2
-
-  # Batch window filters (window_size == send_every) - use streaming filters
-  - platform: copy
-    source_id: source_sensor
-    name: "Min Sensor"
-    id: min_sensor
-    filters:
-      - min:
-          window_size: 5
-          send_every: 5
-          send_first_at: 1
-
-  - platform: copy
-    source_id: source_sensor
-    name: "Max Sensor"
-    id: max_sensor
-    filters:
-      - max:
-          window_size: 5
-          send_every: 5
-          send_first_at: 1
-
-  - platform: copy
-    source_id: source_sensor
-    name: "Moving Avg Sensor"
-    id: moving_avg_sensor
-    filters:
-      - sliding_window_moving_average:
-          window_size: 5
-          send_every: 5
-          send_first_at: 1
-
-# Button to trigger publishing test values
-button:
-  - platform: template
-    name: "Publish Values Button"
-    id: publish_button
-    on_press:
-      - lambda: |-
-          // Publish 10 values: 1.0, 2.0, ..., 10.0
-          for (int i = 1; i <= 10; i++) {
-            id(source_sensor).publish_state(float(i));
-          }
@@ -1,111 +0,0 @@
-esphome:
-  name: uart-mock-modbus-cli-rw
-
-host:
-api:
-logger:
-  level: VERBOSE
-
-external_components:
-  - source:
-      type: local
-      path: EXTERNAL_COMPONENT_PATH
-
-# Dummy uart entry to satisfy modbus's DEPENDENCIES = ["uart"]
-# The actual UART bus used is the uart_mock component below
-uart:
-  baud_rate: 115200
-  port: /dev/null
-
-# Two virtual buses looped back to each other: the client's transmissions reach the server and the
-# server's replies reach the client. auto_start so forwarding is active before the button fires.
-uart_mock:
-  - id: virtual_uart_server
-    baud_rate: 9600
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_client
-              data: !lambda return data;
-  - id: virtual_uart_client
-    baud_rate: 9600
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_server
-              data: !lambda return data;
-
-globals:
-  - id: stored_1
-    type: uint16_t
-    initial_value: "0"
-
-modbus:
-  - uart_id: virtual_uart_server
-    id: virtual_modbus_server
-    role: server
-  - uart_id: virtual_uart_client
-    id: virtual_modbus_client
-    role: client
-    turnaround_time: 10ms
-
-modbus_server:
-  - address: 1
-    modbus_id: virtual_modbus_server
-    registers:
-      # Writable + readable register: the read publishes what it returns, so the test can confirm the
-      # write half of the 0x17 ran before the read half (Modbus 6.17).
-      - address: 0x01
-        value_type: U_WORD
-        read_lambda: |-
-          id(srv_read_1).publish_state(id(stored_1));
-          return id(stored_1);
-        write_lambda: |-
-          id(stored_1) = x;
-          id(srv_write_1).publish_state(x);
-          return true;
-      # Read-only register, returned together with 0x01 by the 2-register read half.
-      - address: 0x02
-        value_type: U_WORD
-        read_lambda: return 0x00AA;
-
-sensor:
-  # Server-side observations.
-  - platform: template
-    name: "srv_write_1"
-    id: srv_write_1
-  - platform: template
-    name: "srv_read_1"
-    id: srv_read_1
-  # Client-side read-back: the values the client's on_response received.
-  - platform: template
-    name: "client_read_0"
-    id: client_read_0
-  - platform: template
-    name: "client_read_1"
-    id: client_read_1
-
-button:
-  - platform: template
-    name: "Start Scenario"
-    id: start_scenario_btn
-    on_press:
-      # FC 0x17: write reg 0x0001 = 0x1234, then read regs 0x0001..0x0002 back in the same transaction.
-      - modbus_client.read_write_multiple_registers:
-          address: 0x01
-          read_address: 0x0001
-          read_count: 2
-          write_address: 0x0001
-          values: [0x1234]
-          on_response:
-            then:
-              - lambda: |-
-                  // values is the read-back block: reg 0x0001 (must be the just-written 0x1234) and reg 0x0002.
-                  if (values.size() >= 2) {
-                    id(client_read_0).publish_state(values[0]);
-                    id(client_read_1).publish_state(values[1]);
-                  }
@@ -1,88 +0,0 @@
-esphome:
-  name: uart-mock-modbus-custom-pdu
-
-host:
-api:
-logger:
-  level: VERBOSE
-
-external_components:
-  - source:
-      type: local
-      path: EXTERNAL_COMPONENT_PATH
-
-# Dummy uart entry to satisfy modbus's DEPENDENCIES = ["uart"]
-# The actual UART bus used is the uart_mock component below
-uart:
-  baud_rate: 115200
-  port: /dev/null
-
-uart_mock:
-  - id: virtual_uart_server
-    baud_rate: 9600
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_controller
-              data: !lambda return data;
-  - id: virtual_uart_controller
-    baud_rate: 9600
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_server
-              data: !lambda return data;
-
-modbus:
-  - uart_id: virtual_uart_server
-    id: virtual_modbus_server
-    role: server
-  - uart_id: virtual_uart_controller
-    id: virtual_modbus_controller
-    role: client
-    turnaround_time: 10ms
-
-modbus_controller:
-  - address: 1
-    modbus_id: virtual_modbus_controller
-    id: modbus_controller_1
-    update_interval: 1s
-
-modbus_server:
-  - address: 1
-    modbus_id: virtual_modbus_server
-    id: modbus_server_1
-    registers:
-      - address: 0x01
-        value_type: U_WORD
-        read_lambda: return 259;
-
-sensor:
-  # Plain read to confirm the controller <-> server link is up.
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "plain_read"
-    address: 0x01
-    register_type: holding
-    value_type: U_WORD
-  # Custom PDU: read holding register 0x0001, count 1. The PDU is
-  # {function code, address hi, address lo, count hi, count lo}; the device
-  # address and CRC are added by the hub. The lambda parses the response payload
-  # (the register value, big-endian).
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "custom_read"
-    custom_pdu: [0x03, 0x00, 0x01, 0x00, 0x01]
-    lambda: |-
-      if (data.size() < 2) return {};
-      return (float) ((data[0] << 8) | data[1]);
-
-button:
-  - platform: template
-    name: "Start Scenario"
-    id: start_scenario_btn
-    # This test does not have anything to start (mock is autostart)
@@ -1,106 +0,0 @@
-esphome:
-  name: uart-mock-modbus-dep-buffer
-
-host:
-api:
-logger:
-  level: VERBOSE
-
-external_components:
-  - source:
-      type: local
-      path: EXTERNAL_COMPONENT_PATH
-
-# Dummy uart entry to satisfy modbus's DEPENDENCIES = ["uart"]
-# The actual UART bus used is the uart_mock component below
-uart:
-  baud_rate: 115200
-  port: /dev/null
-
-uart_mock:
-  - id: virtual_uart_server
-    baud_rate: 9600
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_controller
-              data: !lambda return data;
-  - id: virtual_uart_controller
-    baud_rate: 9600
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_server
-              data: !lambda return data;
-
-globals:
-  - id: reg10
-    type: uint16_t
-    initial_value: "0"
-
-modbus:
-  - uart_id: virtual_uart_server
-    id: virtual_modbus_server
-    role: server
-  - uart_id: virtual_uart_controller
-    id: virtual_modbus_controller
-    role: client
-    turnaround_time: 10ms
-
-modbus_controller:
-  - address: 1
-    modbus_id: virtual_modbus_controller
-    id: modbus_controller_1
-    update_interval: 1s
-
-modbus_server:
-  - address: 1
-    modbus_id: virtual_modbus_server
-    id: modbus_server_1
-    registers:
-      - address: 0x10
-        value_type: U_WORD
-        read_lambda: return id(reg10);
-        write_lambda: |-
-          id(reg10) = x;
-          return true;
-
-# A number whose write_lambda uses the DEPRECATED buffer parameter (fills `payload` with a legacy raw
-# frame as words: device address + function code + data) instead of the new item->write_* API. The write
-# must still land with its legacy semantics, and the one-time deprecation warning must fire only once per
-# entity no matter how many writes happen.
-number:
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "buf_number"
-    id: buf_number
-    address: 0x10
-    register_type: holding
-    value_type: U_WORD
-    min_value: 0
-    max_value: 1000
-    step: 1
-    write_lambda: |-
-      // Legacy raw frame as words: [addr 0x01 | fc 0x06], register 0x0010, value.
-      payload.push_back(0x0106);
-      payload.push_back(0x0010);
-      payload.push_back((uint16_t) x);
-      return {};
-
-# Reports the server-side register so the test can observe that the deprecated buffer write landed.
-sensor:
-  - platform: template
-    name: "written_value"
-    id: written_value
-    update_interval: 0.5s
-    lambda: "return id(reg10);"
-
-button:
-  - platform: template
-    name: "Start Scenario"
-    id: start_scenario_btn
-    # The test drives the writes via number_command; the mock is autostart.
@@ -1,95 +0,0 @@
-esphome:
-  name: uart-mock-modbus-lambda-invert
-
-host:
-api:
-logger:
-  level: VERBOSE
-
-external_components:
-  - source:
-      type: local
-      path: EXTERNAL_COMPONENT_PATH
-
-# Dummy uart entry to satisfy modbus's DEPENDENCIES = ["uart"]
-# The actual UART bus used is the uart_mock component below
-uart:
-  baud_rate: 115200
-  port: /dev/null
-
-uart_mock:
-  - id: virtual_uart_server
-    baud_rate: 9600
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_controller
-              data: !lambda return data;
-  - id: virtual_uart_controller
-    baud_rate: 9600
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_server
-              data: !lambda return data;
-
-globals:
-  - id: reg40
-    type: uint16_t
-    initial_value: "5"
-
-modbus:
-  - uart_id: virtual_uart_server
-    id: virtual_modbus_server
-    role: server
-  - uart_id: virtual_uart_controller
-    id: virtual_modbus_controller
-    role: client
-    turnaround_time: 10ms
-
-modbus_controller:
-  - address: 1
-    modbus_id: virtual_modbus_controller
-    id: modbus_controller_1
-    update_interval: 1s
-
-modbus_server:
-  - address: 1
-    modbus_id: virtual_modbus_server
-    id: modbus_server_1
-    registers:
-      - address: 0x40
-        value_type: U_WORD
-        read_lambda: return id(reg40);
-        write_lambda: id(reg40) = x; return true;
-
-# An active-low holding switch: the write_lambda inverts the wire value, but the entity must still
-# report the REQUESTED state. assumed_state keeps the register unpolled, so the published state comes
-# only from write_state() - turning ON writes 0x0000 yet the switch shows ON.
-switch:
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "invert_switch"
-    register_type: holding
-    address: 0x40
-    assumed_state: true
-    write_lambda: |-
-      return !x;
-
-sensor:
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "reg_40"
-    address: 0x40
-    register_type: holding
-    value_type: U_WORD
-
-button:
-  - platform: template
-    name: "Start Scenario"
-    id: start_scenario_btn
-    # This test does not have anything to start (mock is autostart)
@@ -1,97 +0,0 @@
-esphome:
-  name: uart-mock-modbus-lambda-write
-
-host:
-api:
-logger:
-  level: VERBOSE
-
-external_components:
-  - source:
-      type: local
-      path: EXTERNAL_COMPONENT_PATH
-
-# Dummy uart entry to satisfy modbus's DEPENDENCIES = ["uart"]
-# The actual UART bus used is the uart_mock component below
-uart:
-  baud_rate: 115200
-  port: /dev/null
-
-uart_mock:
-  - id: virtual_uart_server
-    baud_rate: 9600
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_controller
-              data: !lambda return data;
-  - id: virtual_uart_controller
-    baud_rate: 9600
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_server
-              data: !lambda return data;
-
-globals:
-  - id: reg30
-    type: uint16_t
-    initial_value: "0"
-
-modbus:
-  - uart_id: virtual_uart_server
-    id: virtual_modbus_server
-    role: server
-  - uart_id: virtual_uart_controller
-    id: virtual_modbus_controller
-    role: client
-    turnaround_time: 10ms
-
-modbus_controller:
-  - address: 1
-    modbus_id: virtual_modbus_controller
-    id: modbus_controller_1
-    update_interval: 1s
-
-modbus_server:
-  - address: 1
-    modbus_id: virtual_modbus_server
-    id: modbus_server_1
-    registers:
-      - address: 0x30
-        value_type: U_WORD
-        read_lambda: return id(reg30);
-        write_lambda: id(reg30) = x; return true;
-
-# A COIL-type switch (assumed_state, write-only) whose write_lambda ignores its own coil type and instead
-# drives a HOLDING-REGISTER write on the mock server through the entity itself: `item` IS the command, so
-# item->write_single_register() sends a register write from a coil entity (cross-type). Returning nothing
-# (an empty optional) tells the write path the lambda already dispatched the frame - no default coil write.
-switch:
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "cross_switch"
-    register_type: coil
-    address: 0x00
-    assumed_state: true
-    write_lambda: |-
-      item->write_single_register(0x30, x ? 1234 : 0);
-      return {};
-
-sensor:
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "reg_30"
-    address: 0x30
-    register_type: holding
-    value_type: U_WORD
-
-button:
-  - platform: template
-    name: "Start Scenario"
-    id: start_scenario_btn
-    # This test does not have anything to start (mock is autostart)
@@ -0,0 +1,233 @@
+esphome:
+  name: uart-mock-modbus-loopback
+
+host:
+api:
+logger:
+  level: VERBOSE
+
+external_components:
+  - source:
+      type: local
+      path: EXTERNAL_COMPONENT_PATH
+
+# Dummy uart entry to satisfy modbus's DEPENDENCIES = ["uart"]
+# The actual UART bus used is the uart_mock component below
+uart:
+  baud_rate: 115200
+  port: /dev/null
+
+# Shared loopback fixture (see the shared_yaml markers in the test file);
+# register spaces are disjoint so each test only observes its own entities.
+uart_mock:
+  - id: virtual_uart_server
+    baud_rate: 9600
+    auto_start: true
+    debug:
+    on_tx:
+      - then:
+          - uart_mock.inject_rx:
+              id: virtual_uart_controller
+              data: !lambda return data;
+  - id: virtual_uart_controller
+    baud_rate: 9600
+    auto_start: true
+    debug:
+    on_tx:
+      - then:
+          - uart_mock.inject_rx:
+              id: virtual_uart_server
+              data: !lambda return data;
+
+globals:
+  - id: reg10
+    type: uint16_t
+    initial_value: "100"
+  - id: reg11
+    type: uint16_t
+    initial_value: "200"
+  - id: reg12
+    type: uint16_t
+    initial_value: "300"
+  - id: reg13
+    type: uint16_t
+    initial_value: "0xABCD"
+  - id: reg30
+    type: uint16_t
+    initial_value: "0"
+  - id: reg40
+    type: uint16_t
+    initial_value: "5"
+  - id: reg50
+    type: uint16_t
+    initial_value: "0"
+
+modbus:
+  - uart_id: virtual_uart_server
+    id: virtual_modbus_server
+    role: server
+  - uart_id: virtual_uart_controller
+    id: virtual_modbus_controller
+    role: client
+    turnaround_time: 10ms
+
+modbus_controller:
+  - address: 1
+    modbus_id: virtual_modbus_controller
+    id: modbus_controller_1
+    update_interval: 1s
+
+modbus_server:
+  - address: 1
+    modbus_id: virtual_modbus_server
+    registers:
+      - address: 0x01
+        value_type: U_WORD
+        read_lambda: return 259;
+      - address: 0x10
+        value_type: U_WORD
+        read_lambda: return id(reg10);
+        write_lambda: id(reg10) = x; return true;
+      - address: 0x11
+        value_type: U_WORD
+        read_lambda: return id(reg11);
+        write_lambda: id(reg11) = x; return true;
+      - address: 0x12
+        value_type: U_WORD
+        read_lambda: return id(reg12);
+        write_lambda: id(reg12) = x; return true;
+      - address: 0x13
+        value_type: U_WORD
+        read_lambda: return id(reg13);
+      - address: 0x30
+        value_type: U_WORD
+        read_lambda: return id(reg30);
+        write_lambda: id(reg30) = x; return true;
+      - address: 0x40
+        value_type: U_WORD
+        read_lambda: return id(reg40);
+        write_lambda: id(reg40) = x; return true;
+      - address: 0x50
+        value_type: U_WORD
+        read_lambda: return id(reg50);
+        write_lambda: id(reg50) = x; return true;
+
+# Byte-based offset: 2 bytes -> register 0x11 (the old code folded it in as a
+# register count, hitting 0x12). assumed_state keeps the switch write-only.
+switch:
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_1
+    name: "offset_switch"
+    register_type: holding
+    address: 0x10
+    offset: 2
+    assumed_state: true
+  # Reading switch, byte offset 6 -> register 0x13; the pre-fix resolution (0x16)
+  # would draw ILLEGAL_DATA_ADDRESS and never publish.
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_1
+    name: "read_offset_switch"
+    register_type: holding
+    address: 0x10
+    offset: 6
+    bitmask: 0x1
+  # Coil switch whose write_lambda dispatches a holding-register write via `item`;
+  # returning an empty optional suppresses the default coil write.
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_1
+    name: "cross_switch"
+    register_type: coil
+    address: 0x00
+    assumed_state: true
+    write_lambda: |-
+      item->write_single_register(0x30, x ? 1234 : 0);
+      return {};
+  # Active-low: the write_lambda inverts the wire value but the entity must still
+  # report the requested state (assumed_state keeps the register unpolled).
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_1
+    name: "invert_switch"
+    register_type: holding
+    address: 0x40
+    assumed_state: true
+    write_lambda: |-
+      return !x;
+
+# Uses the deprecated buffer parameter (legacy raw frame as words); the write
+# must land and the deprecation warning must fire only once per entity.
+number:
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_1
+    name: "buf_number"
+    id: buf_number
+    address: 0x50
+    register_type: holding
+    value_type: U_WORD
+    min_value: 0
+    max_value: 1000
+    step: 1
+    write_lambda: |-
+      // Legacy raw frame as words: [addr 0x01 | fc 0x06], register 0x0050, value.
+      payload.push_back(0x0106);
+      payload.push_back(0x0050);
+      payload.push_back((uint16_t) x);
+      return {};
+
+sensor:
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_1
+    name: "plain_read"
+    address: 0x01
+    register_type: holding
+    value_type: U_WORD
+  # Custom PDU: read holding register 0x0001; device address and CRC are added
+  # by the hub. The lambda parses the big-endian register value.
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_1
+    name: "custom_read"
+    custom_pdu: [0x03, 0x00, 0x01, 0x00, 0x01]
+    lambda: |-
+      if (data.size() < 2) return {};
+      return (float) ((data[0] << 8) | data[1]);
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_1
+    name: "reg_10"
+    address: 0x10
+    register_type: holding
+    value_type: U_WORD
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_1
+    name: "reg_11"
+    address: 0x11
+    register_type: holding
+    value_type: U_WORD
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_1
+    name: "reg_12"
+    address: 0x12
+    register_type: holding
+    value_type: U_WORD
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_1
+    name: "reg_30"
+    address: 0x30
+    register_type: holding
+    value_type: U_WORD
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_1
+    name: "reg_40"
+    address: 0x40
+    register_type: holding
+    value_type: U_WORD
+  # Reports the server-side register so the test can observe that the deprecated buffer write landed.
+  - platform: template
+    name: "written_value"
+    id: written_value
+    update_interval: 0.5s
+    lambda: "return id(reg50);"
+
+button:
+  - platform: template
+    name: "Start Scenario"
+    id: start_scenario_btn
+    # Nothing to start (mock is autostart); tests drive entities directly
@@ -1,5 +1,5 @@
 esphome:
-  name: uart-mock-modbus-server-contro
+  name: uart-mock-modbus-mesh

 host:
 api:
@@ -17,13 +17,14 @@ uart:
  baud_rate: 115200
  port: /dev/null

+# Shared 3-bus mesh (see the shared_yaml markers): addr 1 = typed read-only
+# registers, addr 5 = the read/write 0x17 target, addr 2/3 on the second
+# server hub. auto_start everywhere: the controller polls at boot, so the
+# forwarding must already be live or early requests generate warnings.
+# Every test presses Start Scenario, so all merged actions fire in every test.
 uart_mock:
  - id: virtual_uart_server
    baud_rate: 9600
-    # auto_start must be true for loopback fixtures: the modbus controller
-    # polls on its update_interval immediately at boot, so the uart_mock
-    # forwarding must already be active or early requests are lost and
-    # generate modbus warnings.
    auto_start: true
    debug:
    on_tx:
@@ -31,35 +32,68 @@ uart_mock:
          - uart_mock.inject_rx:
              id: virtual_uart_controller
              data: !lambda return data;
-  - id: virtual_uart_controller
+          - uart_mock.inject_rx:
+              id: virtual_uart_server_2
+              data: !lambda return data;
+  - id: virtual_uart_server_2
    baud_rate: 9600
-    auto_start: true # See comment on virtual_uart_server above
+    auto_start: true
    debug:
    on_tx:
      - then:
          - uart_mock.inject_rx:
              id: virtual_uart_server
              data: !lambda return data;
+          - uart_mock.inject_rx:
+              id: virtual_uart_controller
+              data: !lambda return data;
+  - id: virtual_uart_controller
+    baud_rate: 9600
+    auto_start: true
+    debug:
+    on_tx:
+      - then:
+          - uart_mock.inject_rx:
+              id: virtual_uart_server
+              data: !lambda return data;
+          - uart_mock.inject_rx:
+              id: virtual_uart_server_2
+              data: !lambda return data;
+
+globals:
+  - id: stored_1
+    type: uint16_t
+    initial_value: "0"

 modbus:
  - uart_id: virtual_uart_server
    id: virtual_modbus_server
    role: server
+  - uart_id: virtual_uart_server_2
+    id: virtual_modbus_server_2
+    role: server
  - uart_id: virtual_uart_controller
-    id: virtual_modbus_controller
+    id: virtual_modbus_client
    role: client
    turnaround_time: 10ms

 modbus_controller:
  - address: 1
-    modbus_id: virtual_modbus_controller
+    modbus_id: virtual_modbus_client
    id: modbus_controller_1
    update_interval: 1s
+  - address: 2
+    modbus_id: virtual_modbus_client
+    id: modbus_controller_2
+    update_interval: 1s
+  - address: 3
+    modbus_id: virtual_modbus_client
+    id: modbus_controller_3
+    update_interval: 1s

 modbus_server:
  - address: 1
    modbus_id: virtual_modbus_server
-    id: modbus_server_1
    registers:
      - address: 0x01
        value_type: U_WORD
@@ -103,6 +137,34 @@ modbus_server:
      - address: 0x28
        value_type: FP32_R
        read_lambda: return 3.14;
+  - address: 5
+    modbus_id: virtual_modbus_server
+    registers:
+      # Writable + readable register: srv_write_1 plus the client's read-back
+      # confirm the write half of the 0x17 ran before the read half (Modbus 6.17).
+      - address: 0x01
+        value_type: U_WORD
+        read_lambda: return id(stored_1);
+        write_lambda: |-
+          id(stored_1) = x;
+          id(srv_write_1).publish_state(x);
+          return true;
+      # Read-only register, returned together with 0x01 by the 2-register read half.
+      - address: 0x02
+        value_type: U_WORD
+        read_lambda: return 0x00AA;
+  - address: 2
+    modbus_id: virtual_modbus_server_2
+    registers:
+      - address: 0x01
+        value_type: U_WORD
+        read_lambda: return 919;
+  - address: 3
+    modbus_id: virtual_modbus_server_2
+    registers:
+      - address: 0x01
+        value_type: U_WORD
+        read_lambda: return 929;

 sensor:
  - platform: modbus_controller
@@ -195,9 +257,46 @@ sensor:
    address: 0x28
    register_type: holding
    value_type: FP32_R
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_2
+    name: "multi_reg_a"
+    address: 0x01
+    register_type: holding
+    value_type: U_WORD
+  - platform: modbus_controller
+    modbus_controller_id: modbus_controller_3
+    name: "multi_reg_b"
+    address: 0x01
+    register_type: holding
+    value_type: U_WORD
+  # client_read_write observations, server- and client-side.
+  - platform: template
+    name: "srv_write_1"
+    id: srv_write_1
+  - platform: template
+    name: "client_read_0"
+    id: client_read_0
+  - platform: template
+    name: "client_read_1"
+    id: client_read_1

 button:
  - platform: template
    name: "Start Scenario"
    id: start_scenario_btn
-    # This test does not have anything to start (mock is autostart)
+    on_press:
+      # FC 0x17: write reg 0x0001 = 0x1234, then read regs 0x0001..0x0002 back in the same transaction.
+      - modbus_client.read_write_multiple_registers:
+          address: 5
+          read_address: 0x0001
+          read_count: 2
+          write_address: 0x0001
+          values: [0x1234]
+          on_response:
+            then:
+              - lambda: |-
+                  // values is the read-back block: reg 0x0001 (must be the just-written 0x1234) and reg 0x0002.
+                  if (values.size() >= 2) {
+                    id(client_read_0).publish_state(values[0]);
+                    id(client_read_1).publish_state(values[1]);
+                  }
@@ -1,138 +0,0 @@
-esphome:
-  name: uart-mock-modbus-reg-offset
-
-host:
-api:
-logger:
-  level: VERBOSE
-
-external_components:
-  - source:
-      type: local
-      path: EXTERNAL_COMPONENT_PATH
-
-# Dummy uart entry to satisfy modbus's DEPENDENCIES = ["uart"]
-# The actual UART bus used is the uart_mock component below
-uart:
-  baud_rate: 115200
-  port: /dev/null
-
-uart_mock:
-  - id: virtual_uart_server
-    baud_rate: 9600
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_controller
-              data: !lambda return data;
-  - id: virtual_uart_controller
-    baud_rate: 9600
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_server
-              data: !lambda return data;
-
-globals:
-  - id: reg10
-    type: uint16_t
-    initial_value: "100"
-  - id: reg11
-    type: uint16_t
-    initial_value: "200"
-  - id: reg12
-    type: uint16_t
-    initial_value: "300"
-  - id: reg13
-    type: uint16_t
-    initial_value: "0xABCD"
-
-modbus:
-  - uart_id: virtual_uart_server
-    id: virtual_modbus_server
-    role: server
-  - uart_id: virtual_uart_controller
-    id: virtual_modbus_controller
-    role: client
-    turnaround_time: 10ms
-
-modbus_controller:
-  - address: 1
-    modbus_id: virtual_modbus_controller
-    id: modbus_controller_1
-    update_interval: 1s
-
-modbus_server:
-  - address: 1
-    modbus_id: virtual_modbus_server
-    id: modbus_server_1
-    registers:
-      - address: 0x10
-        value_type: U_WORD
-        read_lambda: return id(reg10);
-        write_lambda: id(reg10) = x; return true;
-      - address: 0x11
-        value_type: U_WORD
-        read_lambda: return id(reg11);
-        write_lambda: id(reg11) = x; return true;
-      - address: 0x12
-        value_type: U_WORD
-        read_lambda: return id(reg12);
-        write_lambda: id(reg12) = x; return true;
-      - address: 0x13
-        value_type: U_WORD
-        read_lambda: return id(reg13);
-        write_lambda: id(reg13) = x; return true;
-
-# A holding-register switch at 0x10 with a 2-BYTE offset. offset is byte-based, so the write must target
-# register 0x10 + 2/2 = 0x11. The old (pre-fix) behavior folded offset into the address as a register
-# count, hitting 0x12 instead. assumed_state keeps the switch write-only so it does not read any register.
-switch:
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "offset_switch"
-    register_type: holding
-    address: 0x10
-    offset: 2
-    assumed_state: true
-  # A holding-register switch that READS its state. Byte offset 6 -> register 0x10 + 6/2 = 0x13. Post-fix
-  # the switch itself resolves to 0x13 (the even byte offset folds into the address as whole registers) and
-  # joins the 0x10..0x13 range, so no separate 0x13 sensor is needed. Pre-fix the whole byte offset folds
-  # into the address (0x16), where the server answers ILLEGAL_DATA_ADDRESS and the switch never publishes.
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "read_offset_switch"
-    register_type: holding
-    address: 0x10
-    offset: 6
-    bitmask: 0x1
-
-sensor:
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "reg_10"
-    address: 0x10
-    register_type: holding
-    value_type: U_WORD
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "reg_11"
-    address: 0x11
-    register_type: holding
-    value_type: U_WORD
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "reg_12"
-    address: 0x12
-    register_type: holding
-    value_type: U_WORD
-
-button:
-  - platform: template
-    name: "Start Scenario"
-    id: start_scenario_btn
-    # This test does not have anything to start (mock is autostart)
@@ -1,124 +0,0 @@
-esphome:
-  name: uart-mock-modbus-server-test
-
-host:
-api:
-logger:
-  level: VERBOSE
-
-external_components:
-  - source:
-      type: local
-      path: EXTERNAL_COMPONENT_PATH
-
-# Dummy uart entry to satisfy modbus's DEPENDENCIES = ["uart"]
-# The actual UART bus used is the uart_mock component below
-uart:
-  baud_rate: 115200
-  port: /dev/null
-
-uart_mock:
-  - id: virtual_uart_dev
-    baud_rate: 9600
-    rx_full_threshold: 120
-    rx_timeout: 2
-    auto_start: false
-    debug:
-    injections:
-      - delay: 100ms
-        inject_rx: [0x01, 0x03, 0x00, 0x03, 0x00, 0x01, 0x74, 0x0A] #  Read holding register 3 on device 1 (basic_read)
-      - delay: 100ms
-        #  Read holding register 7 on device 2
-        #  Reply from device 2
-        #  Read holding register 5 on device 1 (read_after_peer_response)
-        inject_rx:
-          [
-            0x02,
-            0x03,
-            0x00,
-            0x07,
-            0x00,
-            0x01,
-            0x35,
-            0xF8,
-            0x02,
-            0x03,
-            0x02,
-            0x00,
-            0xF0,
-            0xFC,
-            0x00,
-            0x01,
-            0x03,
-            0x00,
-            0x05,
-            0x00,
-            0x01,
-            0x94,
-            0x0B,
-          ]
-      - delay: 100ms
-        inject_rx: [0x02, 0x03, 0x00, 0x07, 0x00, 0x01, 0x35, 0xF8] #  Read holding register 7 on device 2, with no response
-      - delay: 100ms
-        #  Read holding register 7 on device 2, with no response
-        #  Read holding register A on device 1 (read_after_peer_timeout)
-        inject_rx:
-          [
-            0x02,
-            0x03,
-            0x00,
-            0x07,
-            0x00,
-            0x01,
-            0x35,
-            0xF8,
-            0x01,
-            0x03,
-            0x00,
-            0x0A,
-            0x00,
-            0x01,
-            0xA4,
-            0x08,
-          ]
-
-modbus:
-  uart_id: virtual_uart_dev
-  role: server
-
-modbus_server:
-  - address: 1
-    registers:
-      - address: 0x03
-        value_type: U_WORD
-        read_lambda: |-
-          id(basic_read).publish_state(1);
-          return 1;
-      - address: 0x05
-        value_type: U_WORD
-        read_lambda: |-
-          id(read_after_peer_response).publish_state(1);
-          return 1;
-      - address: 0x0A
-        value_type: U_WORD
-        read_lambda: |-
-          id(read_after_peer_timeout).publish_state(1);
-          return 1;
-
-sensor:
-  - platform: template
-    name: "basic_read"
-    id: basic_read
-  - platform: template
-    name: "read_after_peer_response"
-    id: read_after_peer_response
-  - platform: template
-    name: "read_after_peer_timeout"
-    id: read_after_peer_timeout
-
-button:
-  - platform: template
-    name: "Start Scenario"
-    id: start_scenario_btn
-    on_press:
-      - lambda: "id(virtual_uart_dev).start_scenario();"
@@ -1,116 +0,0 @@
-esphome:
-  name: uart-mock-modbus-server-mult
-
-host:
-api:
-logger:
-  level: VERBOSE
-
-external_components:
-  - source:
-      type: local
-      path: EXTERNAL_COMPONENT_PATH
-
-# Dummy uart entry to satisfy modbus's DEPENDENCIES = ["uart"]
-# The actual UART bus used is the uart_mock component below
-uart:
-  baud_rate: 115200
-  port: /dev/null
-
-uart_mock:
-  - id: virtual_uart_server
-    baud_rate: 9600
-    # auto_start must be true for loopback fixtures: the modbus controller
-    # polls on its update_interval immediately at boot, so the uart_mock
-    # forwarding must already be active or early requests are lost and
-    # generate modbus warnings.
-    auto_start: true
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_controller
-              data: !lambda return data;
-          - uart_mock.inject_rx:
-              id: virtual_uart_server_2
-              data: !lambda return data;
-  - id: virtual_uart_server_2
-    baud_rate: 9600
-    auto_start: true # See comment on virtual_uart_server above
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_server
-              data: !lambda return data;
-          - uart_mock.inject_rx:
-              id: virtual_uart_controller
-              data: !lambda return data;
-  - id: virtual_uart_controller
-    baud_rate: 9600
-    auto_start: true # See comment on virtual_uart_server above
-    debug:
-    on_tx:
-      - then:
-          - uart_mock.inject_rx:
-              id: virtual_uart_server
-              data: !lambda return data;
-          - uart_mock.inject_rx:
-              id: virtual_uart_server_2
-              data: !lambda return data;
-
-modbus:
-  - uart_id: virtual_uart_server
-    id: virtual_modbus_server
-    role: server
-  - uart_id: virtual_uart_server_2
-    id: virtual_modbus_server_2
-    role: server
-  - uart_id: virtual_uart_controller
-    id: virtual_modbus_client
-    role: client
-    turnaround_time: 10ms
-
-modbus_controller:
-  - address: 1
-    modbus_id: virtual_modbus_client
-    update_interval: 1s
-    id: modbus_controller_1
-  - address: 2
-    modbus_id: virtual_modbus_client
-    update_interval: 1s
-    id: modbus_controller_2
-
-modbus_server:
-  - address: 1
-    modbus_id: virtual_modbus_server
-    registers:
-      - address: 0x01
-        value_type: U_WORD
-        read_lambda: return 919;
-  - address: 2
-    modbus_id: virtual_modbus_server_2
-    registers:
-      - address: 0x01
-        value_type: U_WORD
-        read_lambda: return 929;
-
-sensor:
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_1
-    name: "reg_u_word"
-    address: 0x01
-    register_type: holding
-    value_type: U_WORD
-  - platform: modbus_controller
-    modbus_controller_id: modbus_controller_2
-    name: "reg_u_word_2"
-    address: 0x01
-    register_type: holding
-    value_type: U_WORD
-
-button:
-  - platform: template
-    name: "Start Scenario"
-    id: start_scenario_btn
-    # This test does not have anything to start (mock is autostart)
@@ -1,5 +1,5 @@
 esphome:
-  name: uart-mock-modbus-srv-rw
+  name: uart-mock-modbus-srv-injected

 host:
 api:
@@ -17,6 +17,8 @@ uart:
  baud_rate: 115200
  port: /dev/null

+# Shared server-role fixture (see the shared_yaml markers in the test file);
+# the injections concatenate and each test waits only on its own sensors.
 uart_mock:
  - id: virtual_uart_dev
    baud_rate: 9600
@@ -25,18 +27,31 @@ uart_mock:
    auto_start: false
    debug:
    injections:
-      # FC 0x17 Read/Write Multiple Registers on device 1:
-      #   write reg 0x0001 = 0x1234 (qty 1), then read regs 0x0001..0x0002 (qty 2).
-      # Per Modbus 6.17 the write is performed before the read, so reg 0x0001 must
-      # read back the just-written 0x1234 in the same request.
+      - delay: 100ms
+        inject_rx: [0x01, 0x03, 0x00, 0x03, 0x00, 0x01, 0x74, 0x0A] #  Read holding register 3 on device 1 (basic_read)
+      - delay: 100ms
+        #  Read holding register 7 on device 2, its reply, then read holding
+        #  register 5 on device 1 (read_after_peer_response)
+        inject_rx: [0x02, 0x03, 0x00, 0x07, 0x00, 0x01, 0x35, 0xF8,
+                    0x02, 0x03, 0x02, 0x00, 0xF0, 0xFC,
+                    0x00, 0x01, 0x03, 0x00, 0x05, 0x00, 0x01, 0x94, 0x0B]
+      - delay: 100ms
+        inject_rx: [0x02, 0x03, 0x00, 0x07, 0x00, 0x01, 0x35, 0xF8] #  Read holding register 7 on device 2, with no response
+      - delay: 100ms
+        #  Read holding register 7 on device 2 with no response, then read
+        #  holding register A on device 1 (read_after_peer_timeout)
+        inject_rx: [0x02, 0x03, 0x00, 0x07, 0x00, 0x01, 0x35, 0xF8,
+                    0x01, 0x03, 0x00, 0x0A, 0x00, 0x01, 0xA4, 0x08]
+      # FC 0x17 on device 1: write reg 0x0001 = 0x1234 then read 0x0001..0x0002;
+      # per Modbus 6.17 the write runs first, so 0x0001 must read back 0x1234.
      - delay: 100ms
        inject_rx:
          [0x01, 0x17, 0x00, 0x01, 0x00, 0x02, 0x00, 0x01, 0x00, 0x01, 0x02, 0x12, 0x34, 0x49, 0xD8]
-      # FC 0x17: write reg 0x0003 = 0x5678 (qty 1), then read reg 0x0003 (qty 1) -
+      # FC 0x17: write reg 0x0006 = 0x5678 (qty 1), then read reg 0x0006 (qty 1) -
      # a write and read targeting a different register block.
      - delay: 100ms
        inject_rx:
-          [0x01, 0x17, 0x00, 0x03, 0x00, 0x01, 0x00, 0x03, 0x00, 0x01, 0x02, 0x56, 0x78, 0x9B, 0x10]
+          [0x01, 0x17, 0x00, 0x06, 0x00, 0x01, 0x00, 0x06, 0x00, 0x01, 0x02, 0x56, 0x78, 0x8B, 0x55]

 globals:
  - id: stored_1
@@ -70,8 +85,18 @@ modbus_server:
        read_lambda: |-
          id(rw_read_2).publish_state(0x00AA);
          return 0x00AA;
-      # Second writable + readable register, targeted by the second request.
      - address: 0x03
+        value_type: U_WORD
+        read_lambda: |-
+          id(basic_read).publish_state(1);
+          return 1;
+      - address: 0x05
+        value_type: U_WORD
+        read_lambda: |-
+          id(read_after_peer_response).publish_state(1);
+          return 1;
+      # Second writable + readable register, targeted by the second FC 0x17 request.
+      - address: 0x06
        value_type: U_WORD
        read_lambda: |-
          id(rw_read_3).publish_state(id(stored_3));
@@ -80,8 +105,22 @@ modbus_server:
          id(stored_3) = x;
          id(rw_write_3).publish_state(x);
          return true;
+      - address: 0x0A
+        value_type: U_WORD
+        read_lambda: |-
+          id(read_after_peer_timeout).publish_state(1);
+          return 1;

 sensor:
+  - platform: template
+    name: "basic_read"
+    id: basic_read
+  - platform: template
+    name: "read_after_peer_response"
+    id: read_after_peer_response
+  - platform: template
+    name: "read_after_peer_timeout"
+    id: read_after_peer_timeout
  - platform: template
    name: "rw_write_1"
    id: rw_write_1
@@ -1,7 +1,7 @@
 """Helpers for manipulating the host platform's preferences file.

 ESPHome's host platform stores preferences in
-``~/.esphome/prefs/<app_name>.prefs`` using a simple binary layout that
+``$ESPHOME_PREFDIR/<app_name>.prefs`` using a simple binary layout that
 mirrors ``HostPreferences::sync()``:
 ``[uint32_t key][uint8_t len][uint8_t data[len]]`` per entry.

@@ -11,13 +11,21 @@ boot (e.g. forcing safe mode) or to clear stale state between runs.

 from __future__ import annotations

+import os
 from pathlib import Path
 import struct


 def host_prefs_path(device_name: str) -> Path:
-    """Return the on-disk prefs file path for a host-platform device."""
-    return Path.home() / ".esphome" / "prefs" / f"{device_name}.prefs"
+    """Return the on-disk prefs file path for a host-platform device.
+
+    Requires ESPHOME_PREFDIR, which the autouse isolated_preferences fixture
+    sets; refusing the ~/.esphome/prefs fallback keeps tests off real user
+    data if the fixture is ever bypassed."""
+    prefdir = os.environ.get("ESPHOME_PREFDIR")
+    if not prefdir:
+        raise RuntimeError("ESPHOME_PREFDIR is not set; refusing the real prefs dir")
+    return Path(prefdir) / f"{device_name}.prefs"


 def clear_host_prefs(device_name: str) -> None:
@@ -0,0 +1,175 @@
+"""Integration tests for the api outgoing_connection option.
+
+The device dials out to the test's listener when no dial-back target client is
+connected. The listener plays the Home Assistant side over the accepted socket
+using aioesphomeapi's sans-IO Noise handshake: the device sends its server
+hello first so the listener could pick the right key, and the NNpsk0 handshake
+then verifies both sides. Protocol roles stay unchanged, so the client speaks
+exactly the same frames as over a normal connection. A client becomes the
+remembered dial-back target by setting the outgoing_connection_target flag in
+its hello.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import socket
+from typing import Any
+
+from aioesphomeapi import api_pb2
+import pytest
+
+from .raw_api_client import MESSAGE_TYPE_OF
+from .types import RunCompiledFunction
+
+KEY = "bOFFzzvfpg5DB94DuBGLXD/hMnhpDKgP9UQyBulwWVU="
+DEVICE_NAME = "outgoing-conn-test"
+HA_CLIENT_INFO = "Home Assistant 2026.8.0"
+# HelloRequest field 4 (outgoing_connection_target) as raw protobuf bytes; the
+# installed aioesphomeapi's api_pb2 predates the field, so append it manually.
+HELLO_TARGET_FLAG = b"\x20\x01"
+
+
+def _frame(payload: bytes) -> bytes:
+    return bytes((0x01, len(payload) >> 8, len(payload) & 0xFF)) + payload
+
+
+async def _read_frame(reader: asyncio.StreamReader, timeout: float = 10.0) -> bytes:
+    header = await asyncio.wait_for(reader.readexactly(3), timeout)
+    assert header[0] == 0x01, f"Bad frame indicator: {header[0]}"
+    return await asyncio.wait_for(
+        reader.readexactly((header[1] << 8) | header[2]), timeout
+    )
+
+
+def _check_server_hello(server_hello: bytes) -> None:
+    assert server_hello[0] == 0x01, "Bad chosen proto in server hello"
+    name, mac, _rest = server_hello[1:].split(b"\x00", 2)
+    assert name.decode() == DEVICE_NAME
+    assert len(mac) == 12, f"Expected bare MAC, got {mac!r}"
+
+
+async def _run_ha_session(
+    reader: asyncio.StreamReader,
+    writer: asyncio.StreamWriter,
+    *,
+    device_dialed_out: bool,
+) -> None:
+    """Handshake and exchange the usual first messages as Home Assistant would."""
+    # Lazy import per the module's own contract (pulls in the noise stack)
+    from aioesphomeapi.noise import NoiseHandshake
+
+    if device_dialed_out:
+        # On an outgoing connection the device announces itself first so the
+        # peer can pick the matching key before its PSK-mixed first message.
+        _check_server_hello(await _read_frame(reader))
+
+    handshake = NoiseHandshake(KEY, b"NoiseAPIInit\x00\x00")
+    writer.write(b"\x01\x00\x00" + _frame(b"\x00" + handshake.write_message()))
+    await writer.drain()
+
+    if not device_dialed_out:
+        _check_server_hello(await _read_frame(reader))
+
+    reply = await _read_frame(reader)
+    assert reply[0] == 0, f"Handshake rejected: {reply[1:].decode(errors='replace')}"
+    handshake.read_message(reply[1:])
+    encrypt_cipher, decrypt_cipher = handshake.get_ciphers()
+
+    async def transact(msg: Any, response_cls: Any, extra_payload: bytes = b"") -> Any:
+        msg_type = MESSAGE_TYPE_OF[type(msg)]
+        payload = msg.SerializeToString() + extra_payload
+        plaintext = (
+            bytes(
+                (msg_type >> 8, msg_type & 0xFF, len(payload) >> 8, len(payload) & 0xFF)
+            )
+            + payload
+        )
+        writer.write(_frame(encrypt_cipher.encrypt(plaintext)))
+        await writer.drain()
+        want = MESSAGE_TYPE_OF[response_cls]
+        while True:
+            plain = decrypt_cipher.decrypt(await _read_frame(reader))
+            if ((plain[0] << 8) | plain[1]) == want:
+                response = response_cls()
+                response.ParseFromString(bytes(plain[4:]))
+                return response
+
+    # Declare this client a dial-back target in the hello
+    await transact(
+        api_pb2.HelloRequest(client_info=HA_CLIENT_INFO),
+        api_pb2.HelloResponse,
+        extra_payload=HELLO_TARGET_FLAG,
+    )
+    device_info = await transact(
+        api_pb2.DeviceInfoRequest(), api_pb2.DeviceInfoResponse
+    )
+    assert device_info.name == DEVICE_NAME
+
+
+async def _serve_home_assistant(listener: socket.socket) -> None:
+    """Accept one dial-in from the device and run the client side over it."""
+    loop = asyncio.get_running_loop()
+    conn, _ = await asyncio.wait_for(loop.sock_accept(listener), timeout=30)
+    reader, writer = await asyncio.open_connection(sock=conn)
+    try:
+        await _run_ha_session(reader, writer, device_dialed_out=True)
+    finally:
+        writer.close()
+
+
+@pytest.mark.asyncio
+async def test_api_outgoing_connection(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+) -> None:
+    """With a configured host the device dials out and speaks the normal API."""
+    listener = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    listener.bind(("127.0.0.1", 0))
+    listener.listen(2)
+    listener.setblocking(False)
+    port = listener.getsockname()[1]
+
+    try:
+        yaml = yaml_config.replace("OUTGOING_PORT", str(port))
+        async with run_compiled(yaml):
+            await _serve_home_assistant(listener)
+    finally:
+        listener.close()
+
+
+@pytest.mark.asyncio
+async def test_api_outgoing_connection_remembered(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    unused_tcp_port: int,
+) -> None:
+    """No host configured: the device remembers the client whose hello carried
+    the dial-back flag and dials that address after a restart."""
+    listener = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    # Bound but not yet listening so first-phase dials cannot queue stale
+    # connections; whether the device attempts any dial before the restart
+    # is timing dependent and not asserted here.
+    listener.bind(("127.0.0.1", 0))
+    port = listener.getsockname()[1]
+
+    try:
+        yaml = yaml_config.replace("OUTGOING_PORT", str(port))
+
+        async with run_compiled(yaml):
+            # Connect inbound with the dial-back flag; the device persists the
+            # peer address during the hello.
+            reader, writer = await asyncio.open_connection("127.0.0.1", unused_tcp_port)
+            try:
+                await _run_ha_session(reader, writer, device_dialed_out=False)
+            finally:
+                writer.close()
+
+        # Restart with the same preferences: the device now dials the
+        # remembered address on its own.
+        listener.listen(2)
+        listener.setblocking(False)
+        async with run_compiled(yaml):
+            await _serve_home_assistant(listener)
+    finally:
+        listener.close()
@@ -5,7 +5,7 @@ import re

 import pytest

-from .types import RunCompiledFunction
+from .types import APIClientConnectedFactory, RunCompiledFunction


@pytest.mark.asyncio
@@ -16,7 +16,9 @@ async def test_api_reboot_timeout(
    """Test that the device reboots when no API clients connect within the timeout."""
    loop = asyncio.get_running_loop()
    reboot_future = loop.create_future()
-    reboot_pattern = re.compile(r"No clients; rebooting")
+    # The harness port probe always connects without authenticating, so the
+    # reboot deterministically reports the unauthenticated form
+    reboot_pattern = re.compile(r"none authenticated; rebooting")

    def check_output(line: str) -> None:
        """Check output for reboot message."""
@@ -33,3 +35,30 @@ async def test_api_reboot_timeout(
            pytest.fail("Device did not reboot within expected timeout")

    # Test passes if we get here - reboot was detected
+
+
+@pytest.mark.asyncio
+async def test_api_reboot_timeout_after_authenticated_disconnect(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """An authenticated disconnect resets the flag; the clean branch reboots."""
+    loop = asyncio.get_running_loop()
+    reboot_future = loop.create_future()
+    reboot_pattern = re.compile(r"No clients; rebooting")
+
+    def check_output(line: str) -> None:
+        """Check output for reboot message."""
+        if not reboot_future.done() and reboot_pattern.search(line):
+            reboot_future.set_result(True)
+
+    async with run_compiled(yaml_config, line_callback=check_output):
+        # An authenticated session refreshes the watchdog and clears the
+        # unauthenticated flag the harness probe set
+        async with api_client_connected() as client:
+            await client.device_info()
+        try:
+            await asyncio.wait_for(reboot_future, timeout=5.0)
+        except TimeoutError:
+            pytest.fail("Device did not reboot within expected timeout")
@@ -24,7 +24,6 @@ from .types import (
    RunCompiledFunction,
 )

-pytestmark = pytest.mark.usefixtures("isolated_preferences")
 NEW_KEY = PROVISIONING_PSK


@@ -41,15 +41,6 @@ async def _poll_until_exists(path: Path) -> None:
        await asyncio.sleep(0.05)


-@pytest.fixture(autouse=True)
-def isolated_preferences(monkeypatch: pytest.MonkeyPatch, tmp_path) -> Path:
-    """Keep host preferences per-test so this test never touches the real
-    ~/.esphome/prefs and never races other tests over ESPHOME_PREFDIR."""
-    prefdir = tmp_path / "prefs"
-    monkeypatch.setenv("ESPHOME_PREFDIR", str(prefdir))
-    return prefdir / f"{DEVICE_NAME}.prefs"
-
-
@pytest.mark.asyncio
 async def test_host_preferences_suspend_resume(
    yaml_config: str,
@@ -58,7 +49,7 @@ async def test_host_preferences_suspend_resume(
    isolated_preferences: Path,
 ) -> None:
    """Test that a running syncer flushes, a suspended one doesn't, and resume restores flushing."""
-    pref_file = isolated_preferences
+    pref_file = isolated_preferences / f"{DEVICE_NAME}.prefs"

    loop = asyncio.get_running_loop()
    saved_in_memory = loop.create_future()
@@ -11,14 +11,6 @@ from .state_utils import InitialStateHelper, require_entity
 from .types import APIClientConnectedFactory, RunCompiledFunction


-@pytest.fixture(autouse=True)
-def isolated_preferences(monkeypatch: pytest.MonkeyPatch, tmp_path) -> None:
-    """Keep host preferences per-test so RESTORE_AND_ON never loads a stale value left
-    behind by a previous run (host preferences otherwise persist to ~/.esphome/prefs,
-    keyed only by device name)."""
-    monkeypatch.setenv("ESPHOME_PREFDIR", str(tmp_path / "prefs"))
-
-
@pytest.mark.asyncio
 async def test_light_initial_state(
    yaml_config: str,
@@ -173,6 +173,7 @@ async def test_uart_mock_modbus_no_threshold(
        _assert_no_modbus_errors(error_log_lines, warning_log_lines)


+@pytest.mark.shared_yaml("uart_mock_modbus_server_injected")
@pytest.mark.asyncio
 async def test_uart_mock_modbus_server(
    yaml_config: str,
@@ -203,6 +204,7 @@ async def test_uart_mock_modbus_server(
        _assert_no_modbus_errors(error_log_lines, warning_log_lines)


+@pytest.mark.shared_yaml("uart_mock_modbus_server_injected")
@pytest.mark.asyncio
 async def test_uart_mock_modbus_server_read_write(
    yaml_config: str,
@@ -231,8 +233,8 @@ async def test_uart_mock_modbus_server_read_write(
            "rw_write_1": 4660,  # 0x1234 written to reg 0x0001
            "rw_read_1": 4660,  # reg 0x0001 reads back the just-written value
            "rw_read_2": 170,  # 0x00AA read from reg 0x0002 in the same request
-            "rw_write_3": 22136,  # 0x5678 written to reg 0x0003
-            "rw_read_3": 22136,  # reg 0x0003 reads back the just-written value
+            "rw_write_3": 22136,  # 0x5678 written to reg 0x0006
+            "rw_read_3": 22136,  # reg 0x0006 reads back the just-written value
        }
    )

@@ -241,7 +243,8 @@ async def test_uart_mock_modbus_server_read_write(
        api_client_connected() as client,
    ):
        await tracker.setup_and_start_scenario(client)
-        await tracker.await_all(futures)
+        # The FC 0x17 injections fire last, behind four earlier 100ms delays
+        await tracker.await_all(futures, timeout=4.0)
        _assert_no_modbus_errors(error_log_lines, warning_log_lines)


@@ -296,6 +299,7 @@ async def test_uart_mock_modbus_server_read_write_invalid(
    )


+@pytest.mark.shared_yaml("uart_mock_modbus_mesh")
@pytest.mark.asyncio
 async def test_uart_mock_modbus_server_controller(
    yaml_config: str,
@@ -485,6 +489,7 @@ async def test_uart_mock_modbus_server_controller_bits(
        _assert_no_modbus_errors(error_log_lines, warning_log_lines)


+@pytest.mark.shared_yaml("uart_mock_modbus_mesh")
@pytest.mark.asyncio
 async def test_uart_mock_modbus_server_controller_multiple(
    yaml_config: str,
@@ -495,7 +500,7 @@ async def test_uart_mock_modbus_server_controller_multiple(

    line_callback, error_log_lines, warning_log_lines = _make_modbus_line_callback()

-    expected_values = {"reg_u_word": 919, "reg_u_word_2": 929}
+    expected_values = {"multi_reg_a": 919, "multi_reg_b": 929}
    tracker = SensorTracker(list(expected_values.keys()))
    futures = tracker.expect_all(expected_values)

@@ -706,6 +711,7 @@ async def test_uart_mock_modbus_shared_address(
        _assert_no_modbus_errors(error_log_lines, warning_log_lines)


+@pytest.mark.shared_yaml("uart_mock_modbus_loopback")
@pytest.mark.asyncio
 async def test_uart_mock_modbus_custom_pdu(
    yaml_config: str,
@@ -932,6 +938,7 @@ async def test_uart_mock_modbus_broadcast_write(
        _assert_no_modbus_errors(error_log_lines, warning_log_lines)


+@pytest.mark.shared_yaml("uart_mock_modbus_mesh")
@pytest.mark.asyncio
 async def test_uart_mock_modbus_client_read_write(
    yaml_config: str,
@@ -947,9 +954,7 @@ async def test_uart_mock_modbus_client_read_write(
    """
    line_callback, error_log_lines, warning_log_lines = _make_modbus_line_callback()

-    tracker = SensorTracker(
-        ["srv_write_1", "srv_read_1", "client_read_0", "client_read_1"]
-    )
+    tracker = SensorTracker(["srv_write_1", "client_read_0", "client_read_1"])
    futures = tracker.expect_all(
        {
            "srv_write_1": 4660,  # server wrote 0x1234 to reg 0x0001
@@ -967,6 +972,7 @@ async def test_uart_mock_modbus_client_read_write(
        _assert_no_modbus_errors(error_log_lines, warning_log_lines)


+@pytest.mark.shared_yaml("uart_mock_modbus_loopback")
@pytest.mark.asyncio
 async def test_uart_mock_modbus_register_offset(
    yaml_config: str,
@@ -1022,6 +1028,7 @@ async def test_uart_mock_modbus_register_offset(
        )


+@pytest.mark.shared_yaml("uart_mock_modbus_loopback")
@pytest.mark.asyncio
 async def test_uart_mock_modbus_lambda_write(
    yaml_config: str,
@@ -1058,6 +1065,7 @@ async def test_uart_mock_modbus_lambda_write(
        await tracker.await_change(wrote_30, "reg_30", timeout=4.0)


+@pytest.mark.shared_yaml("uart_mock_modbus_loopback")
@pytest.mark.asyncio
 async def test_uart_mock_modbus_lambda_invert(
    yaml_config: str,
@@ -1113,6 +1121,7 @@ async def test_uart_mock_modbus_lambda_invert(
        )


+@pytest.mark.shared_yaml("uart_mock_modbus_loopback")
@pytest.mark.asyncio
 async def test_uart_mock_modbus_deprecated_write_buffer(
    yaml_config: str,
@@ -78,17 +78,6 @@ def mock_esp32_platformio_components_to_test() -> Generator[Mock, None, None]:
        yield mock


-@pytest.fixture
-def mock_esp8266_native_components_to_test() -> Generator[Mock, None, None]:
-    """Mock esp8266_native_components_to_test from determine_jobs.
-
-    main() drives both the ``esp8266_native`` boolean output and the
-    ``esp8266_native_components`` CSV from this one function.
-    """
-    with patch.object(determine_jobs, "esp8266_native_components_to_test") as mock:
-        yield mock
-
-
@pytest.fixture
 def mock_determine_cpp_unit_tests() -> Generator[Mock, None, None]:
    """Mock determine_cpp_unit_tests from helpers."""
@@ -117,7 +106,6 @@ def clear_determine_jobs_caches() -> None:
    """Clear all cached functions before each test."""
    determine_jobs._is_clang_tidy_full_scan.cache_clear()
    determine_jobs._component_has_tests.cache_clear()
-    determine_jobs._cached_components_closure.cache_clear()


 def test_main_all_tests_should_run(
@@ -128,7 +116,6 @@ def test_main_all_tests_should_run(
    mock_should_run_import_time: Mock,
    mock_should_run_device_builder: Mock,
    mock_esp32_platformio_components_to_test: Mock,
-    mock_esp8266_native_components_to_test: Mock,
    mock_changed_files: Mock,
    mock_determine_cpp_unit_tests: Mock,
    capsys: pytest.CaptureFixture[str],
@@ -145,7 +132,6 @@ def test_main_all_tests_should_run(
    mock_should_run_import_time.return_value = True
    mock_should_run_device_builder.return_value = True
    mock_esp32_platformio_components_to_test.return_value = ["api", "esp32"]
-    mock_esp8266_native_components_to_test.return_value = ["api", "logger"]
    mock_determine_cpp_unit_tests.return_value = (False, ["wifi", "api", "sensor"])

    # Mock changed_files to return non-component files (to avoid memory impact)
@@ -222,8 +208,6 @@ def test_main_all_tests_should_run(
    assert output["device_builder"] is True
    assert output["esp32_platformio"] is True
    assert output["esp32_platformio_components"] == "api,esp32"
-    assert output["esp8266_native"] is True
-    assert output["esp8266_native_components"] == "api,logger"
    assert output["changed_components"] == ["wifi", "api", "sensor"]
    # changed_components_with_tests will only include components that actually have test files
    assert "changed_components_with_tests" in output
@@ -260,7 +244,6 @@ def test_main_no_tests_should_run(
    mock_should_run_import_time: Mock,
    mock_should_run_device_builder: Mock,
    mock_esp32_platformio_components_to_test: Mock,
-    mock_esp8266_native_components_to_test: Mock,
    mock_changed_files: Mock,
    mock_determine_cpp_unit_tests: Mock,
    capsys: pytest.CaptureFixture[str],
@@ -277,7 +260,6 @@ def test_main_no_tests_should_run(
    mock_should_run_import_time.return_value = False
    mock_should_run_device_builder.return_value = False
    mock_esp32_platformio_components_to_test.return_value = []
-    mock_esp8266_native_components_to_test.return_value = []
    mock_determine_cpp_unit_tests.return_value = (False, [])

    # Mock changed_files to return no component files
@@ -320,8 +302,6 @@ def test_main_no_tests_should_run(
    assert output["device_builder"] is False
    assert output["esp32_platformio"] is False
    assert output["esp32_platformio_components"] == ""
-    assert output["esp8266_native"] is False
-    assert output["esp8266_native_components"] == ""
    assert output["changed_components"] == []
    assert output["changed_components_with_tests"] == []
    assert output["component_test_count"] == 0
@@ -3171,78 +3151,6 @@ def test_memory_impact_elf_layouts_are_found(tmp_path: Path) -> None:
        assert find_elf_path(build_path) == elf, f"{platform} ELF not found"


-@pytest.mark.parametrize(
-    "changed",
-    [
-        "esphome/arduino8266/framework.py",
-        "esphome/build_gen/arduino8266.py",
-        "esphome/components/esp8266/build_surgery.py",
-        # Shared modules the native build depends on
-        "esphome/build_helpers/idedata.py",
-        "esphome/platformio/library.py",
-        # Top-level esphome/*.py modules the backend imports directly
-        "esphome/framework_helpers.py",
-        "esphome/writer.py",
-        # esp8266/__init__.py imports copy_ccache_script from it
-        "esphome/platformio/toolchain.py",
-        # The composite cache action must not ship unexercised
-        ".github/actions/cache-arduino8266/action.yml",
-    ],
-)
-def test_esp8266_native_components_full_list_on_infra_change(changed: str) -> None:
-    """Native-ESP8266 infrastructure changes run the full test list."""
-    with (
-        patch.object(determine_jobs, "changed_files", return_value=[changed]),
-        patch.object(
-            determine_jobs,
-            "get_components_with_dependencies",
-            return_value=["wifi"],
-        ),
-    ):
-        result = determine_jobs.esp8266_native_components_to_test()
-        assert result == sorted(determine_jobs.ESP8266_NATIVE_TEST_COMPONENTS)
-
-
-@pytest.mark.parametrize(
-    ("changed_files", "dependency_closure", "expected"),
-    [
-        # Tested component changed -- narrow to the intersection.
-        (
-            ["esphome/components/mqtt/mqtt_client.cpp"],
-            ["mqtt", "json"],
-            ["mqtt"],
-        ),
-        # Components outside the test set return an empty list (job skipped).
-        (
-            ["esphome/components/wifi/wifi_component.cpp"],
-            ["wifi", "network"],
-            [],
-        ),
-        # espidf infrastructure is not an esp8266-native trigger; the
-        # native backend depends on esphome/build_helpers/ instead.
-        (["esphome/build_gen/espidf.py"], [], []),
-        (["esphome/espidf/toolchain.py"], [], []),
-        (["README.md"], [], []),
-    ],
-)
-def test_esp8266_native_components_to_test_narrowing(
-    changed_files: list[str],
-    dependency_closure: list[str],
-    expected: list[str],
-) -> None:
-    """Component changes narrow the native-ESP8266 test list."""
-    with (
-        patch.object(determine_jobs, "changed_files", return_value=changed_files),
-        patch.object(
-            determine_jobs,
-            "get_components_with_dependencies",
-            return_value=dependency_closure,
-        ),
-    ):
-        result = determine_jobs.esp8266_native_components_to_test()
-        assert result == expected
-
-
 def test_compute_integration_test_buckets_no_durations_full_fanout() -> None:
    """Without recorded durations the fan-out stays at the maximum."""
    files = [f"tests/integration/test_{i:03d}.py" for i in range(15)]
@@ -2122,6 +2122,34 @@ def test_get_cpp_changed_components_independent_of_cwd(
    ) == ["time"]


+def test_fixture_map_includes_shared_yaml_markers() -> None:
+    """Fixtures named only by shared_yaml markers must map to their test file."""
+    helpers.get_fixture_to_test_files.cache_clear()
+    mapping = helpers.get_fixture_to_test_files()
+    for fixture in (
+        "uart_mock_modbus_loopback",
+        "uart_mock_modbus_mesh",
+        "uart_mock_modbus_server_injected",
+    ):
+        assert mapping[fixture] == frozenset(
+            {"tests/integration/test_uart_mock_modbus.py"}
+        )
+
+
+def test_no_orphan_integration_fixtures() -> None:
+    """Every fixture must reach CI test selection; an orphan selects nothing."""
+    helpers.get_fixture_to_test_files.cache_clear()
+    mapping = helpers.get_fixture_to_test_files()
+    fixtures_dir = (Path(__file__).parent.parent / "integration" / "fixtures").resolve()
+    fixtures = list(fixtures_dir.glob("*.yaml"))
+    assert fixtures, f"no fixtures found under {fixtures_dir}"
+    # cache_init is covered via INTEGRATION_TESTS_TRIGGER_FILES instead
+    orphans = [
+        f.stem for f in fixtures if f.stem != "cache_init" and f.stem not in mapping
+    ]
+    assert not orphans, f"fixtures invisible to CI test selection: {orphans}"
+
+
 def test_lpt_partition_balances_skewed_weights() -> None:
    """Heavy items spread across groups instead of clustering."""
    items = [f"i{n}" for n in range(6)]
@@ -236,98 +236,3 @@ def test_run_grouped_test_closes_group_when_subprocess_raises(
        )

    assert "::endgroup::" in capsys.readouterr().out
-
-
-def test_components_empty_match_fails_with_flag(
-    capsys: pytest.CaptureFixture[str],
-) -> None:
-    """Under --fail-on-no-tests, a real component filtered to a platform
-    with no matching test file must not pass CI as a green zero-component
-    compile."""
-    rc = tbc.test_components(
-        ["logger"],
-        "zz-none",
-        "compile",
-        False,
-        enable_grouping=False,
-        fail_on_no_tests=True,
-    )
-    assert rc == 1
-    assert "No tests ran for requested pattern(s): logger" in (capsys.readouterr().out)
-
-
-def test_components_component_with_no_base_file_fails_with_flag(
-    capsys: pytest.CaptureFixture[str],
-    monkeypatch: pytest.MonkeyPatch,
-) -> None:
-    """A component whose fixture matches the platform but whose platform has
-    no base file builds nothing; under the flag that silent zero fails by
-    component name instead of hiding behind other components."""
-    monkeypatch.setattr(tbc, "get_platform_base_files", lambda base_dir: {})
-    rc = tbc.test_components(
-        ["logger"],
-        "esp8266-ard",
-        "compile",
-        False,
-        enable_grouping=False,
-        fail_on_no_tests=True,
-    )
-    assert rc == 1
-    assert "No tests ran for requested pattern(s): logger" in (capsys.readouterr().out)
-
-
-def test_components_blank_list_fails_with_flag(
-    capsys: pytest.CaptureFixture[str],
-) -> None:
-    """A fully blank component list must not slide into the baseline
-    fallback and exit green under the flag."""
-    rc = tbc.test_components(
-        [""], "esp8266-ard", "compile", False, fail_on_no_tests=True
-    )
-    assert rc == 1
-    assert "blank component list" in capsys.readouterr().out
-
-
-def test_components_wildcard_no_match_fails_with_flag(
-    capsys: pytest.CaptureFixture[str],
-) -> None:
-    """A wildcard matching nothing must not degrade to the synthetic
-    baseline build and exit green under the flag."""
-    rc = tbc.test_components(
-        ["zz_no_such*"],
-        "esp8266-ard",
-        "compile",
-        False,
-        enable_grouping=False,
-        fail_on_no_tests=True,
-    )
-    assert rc == 1
-    assert "No components found matching" in capsys.readouterr().out
-
-
-def test_components_empty_match_tolerated_without_flag() -> None:
-    """The esp32-ard smoke leg deliberately builds only the subset with a
-    matching fixture; without the flag an empty match stays green."""
-    assert (
-        tbc.test_components(
-            ["logger"], "zz-none", "compile", False, enable_grouping=False
-        )
-        == 0
-    )
-
-
-def test_components_unknown_component_fails_with_flag(
-    capsys: pytest.CaptureFixture[str],
-) -> None:
-    """A renamed smoke-test component must shrink coverage loudly, not fall
-    into the reference-baseline build."""
-    rc = tbc.test_components(
-        ["no_such_component_xyz"],
-        "esp8266-ard",
-        "compile",
-        False,
-        enable_grouping=False,
-        fail_on_no_tests=True,
-    )
-    assert rc == 1
-    assert "No components found matching" in capsys.readouterr().out
@@ -1,193 +0,0 @@
-"""Tests for the native (non-PlatformIO) toolchain config validation."""
-
-from __future__ import annotations
-
-from collections.abc import Generator
-from pathlib import Path
-from types import SimpleNamespace
-from unittest.mock import patch
-
-import pytest
-
-from esphome.components import esp8266
-from esphome.components.esp8266 import (
-    ARDUINO_FRAMEWORK_SCHEMA,
-    _resolve_toolchain,
-    _validate_native_toolchain,
-)
-import esphome.config_validation as cv
-from esphome.const import (
-    CONF_BOARD,
-    CONF_FRAMEWORK,
-    CONF_PLATFORM_VERSION,
-    CONF_SOURCE,
-    CONF_TOOLCHAIN,
-    CONF_VERSION,
-    Toolchain,
-)
-from esphome.core import CORE, EsphomeError
-from esphome.types import ConfigType
-
-
-@pytest.fixture(autouse=True)
-def _arduino_toolchain() -> Generator[None]:
-    # The suite-wide reset_core fixture clears CORE.toolchain after each test
-    CORE.toolchain = Toolchain.ARDUINO
-    esp8266._DECODE_WARNED_AT.clear()
-    yield
-    esp8266._DECODE_WARNED_AT.clear()
-
-
-def _config(
-    board: str = "nodemcuv2",
-    version: str = "3.1.2",
-    source: str | None = None,
-    platform_version: str | None = None,
-) -> ConfigType:
-    framework: dict[str, str] = {CONF_VERSION: version}
-    if source is not None:
-        framework[CONF_SOURCE] = source
-    if platform_version is not None:
-        framework[CONF_PLATFORM_VERSION] = platform_version
-    # The real schema fills the source/platform_version defaults, so these
-    # tests validate against what config validation actually emits
-    return {
-        CONF_FRAMEWORK: ARDUINO_FRAMEWORK_SCHEMA(framework),
-        CONF_BOARD: board,
-    }
-
-
-def test_valid_config_passes() -> None:
-    config = _config()
-    assert _validate_native_toolchain(config) is config
-
-
-def test_platformio_toolchain_skips_checks() -> None:
-    # 3.0.2 is pio-legal (>= the global 3.0.0 floor) but below the native
-    # toolchain's own 3.1.1 floor; the bogus board only the native path checks
-    CORE.toolchain = Toolchain.PLATFORMIO
-    config = _config(board="not_a_board", version="3.0.2")
-    assert _validate_native_toolchain(config) is config
-
-
-def test_version_below_floor_rejected() -> None:
-    # 3.1.0 has no registry package, so the native floor is 3.1.1
-    with pytest.raises(cv.Invalid, match="3.1.1 or newer"):
-        _validate_native_toolchain(_config(version="3.1.0"))
-
-
-def test_version_at_floor_accepted() -> None:
-    _validate_native_toolchain(_config(version="3.1.1"))
-
-
-def test_custom_platform_version_warns_and_is_dropped(
-    caplog: pytest.LogCaptureFixture,
-) -> None:
-    config = _config(platform_version="platformio/espressif8266@4.0.1")
-    _validate_native_toolchain(config)
-    assert "'platform_version' is ignored" in caplog.text
-    assert CONF_PLATFORM_VERSION not in config[CONF_FRAMEWORK]
-
-
-def test_default_platform_version_does_not_warn(
-    caplog: pytest.LogCaptureFixture,
-) -> None:
-    config = _config()
-    _validate_native_toolchain(config)
-    assert "'platform_version' is ignored" not in caplog.text
-    assert CONF_PLATFORM_VERSION not in config[CONF_FRAMEWORK]
-
-
-def test_custom_source_rejected() -> None:
-    with pytest.raises(cv.Invalid, match="custom framework source"):
-        _validate_native_toolchain(
-            _config(source="https://github.com/esp8266/Arduino.git")
-        )
-
-
-def test_unsupported_board_rejected() -> None:
-    with pytest.raises(cv.Invalid, match="not supported by"):
-        _validate_native_toolchain(_config(board="not_a_board"))
-
-
-def test_yaml_toolchain_key_resolves() -> None:
-    """The documented `toolchain: arduino` YAML key selects the native path."""
-    CORE.toolchain = None
-    _resolve_toolchain({CONF_TOOLCHAIN: Toolchain.ARDUINO})
-    assert CORE.toolchain == Toolchain.ARDUINO
-    assert CORE.using_toolchain_arduino
-
-
-def test_yaml_toolchain_key_defaults_to_platformio() -> None:
-    CORE.toolchain = None
-    _resolve_toolchain({})
-    assert CORE.toolchain == Toolchain.PLATFORMIO
-
-
-def test_decode_pc_native_missing_tools_warns_once(
-    tmp_path: Path, caplog: pytest.LogCaptureFixture
-) -> None:
-    """A stack dump of many addresses produces one missing-tool warning."""
-
-    with (
-        patch(
-            "esphome.arduino8266.toolchain.get_addr2line_path",
-            return_value=tmp_path / "missing-addr2line",
-        ),
-        patch(
-            "esphome.arduino8266.toolchain.get_elf_path",
-            return_value=tmp_path / "missing.elf",
-        ),
-    ):
-        esp8266._decode_pc({}, "40201234")
-        esp8266._decode_pc({}, "40201238")
-    assert caplog.text.count("Cannot decode crash addresses") == 1
-
-
-def test_decode_pc_platformio_missing_tools_warns_once(
-    caplog: pytest.LogCaptureFixture,
-) -> None:
-    """The PlatformIO branch reports a missing addr2line/ELF at the same
-    warning level as the native one; raw undecoded addresses with no
-    stated reason are undiagnosable at default log level."""
-
-    CORE.toolchain = Toolchain.PLATFORMIO
-    idedata = SimpleNamespace(addr2line_path=None, firmware_elf_path=None)
-    with patch("esphome.platformio.toolchain.get_idedata", return_value=idedata):
-        esp8266._decode_pc({}, "40201234")
-        esp8266._decode_pc({}, "40201238")
-    assert caplog.text.count("Cannot decode crash addresses") == 1
-
-
-def test_resolve_toolchain_rejects_unsupported() -> None:
-    """ESP8266 rejects a CLI toolchain it cannot serve, like every platform."""
-
-    CORE.toolchain = Toolchain.SDK_NRF
-    with pytest.raises(cv.Invalid, match="Unsupported toolchain 'sdk-nrf'"):
-        _resolve_toolchain({})
-
-
-def test_run_compile_platformio_falls_through() -> None:
-    """Under toolchain: platformio the hook returns False without touching
-    the native backend; this is what keeps existing users on PlatformIO."""
-    CORE.toolchain = Toolchain.PLATFORMIO
-    with patch("esphome.arduino8266.toolchain.run_compile") as mock_native:
-        assert esp8266.run_compile(SimpleNamespace(), {}) is False
-    mock_native.assert_not_called()
-
-
-def test_run_compile_arduino_failure_raises() -> None:
-    """A non-zero native build fails by name instead of returning success."""
-    CORE.verbose = False
-    with (
-        patch("esphome.arduino8266.toolchain.run_compile", return_value=1),
-        pytest.raises(EsphomeError, match="native build failed"),
-    ):
-        esp8266.run_compile(SimpleNamespace(), {})
-
-
-def test_copy_files_native_skips_platformio_scripts(tmp_path: Path) -> None:
-    """The native build writes no PlatformIO extra scripts."""
-    CORE.build_path = tmp_path
-    esp8266.copy_files()
-    assert list(tmp_path.iterdir()) == []
@@ -1429,3 +1429,12 @@ async def test_add_platformio_options_native_arduino(
    assert "board_build.ldscript is ignored" in caplog.text
    assert "'arduino' toolchain" in caplog.text
    assert "upload_speed" not in caplog.text
+
+
+def test_esp8266_rejects_unsupported_cli_toolchain() -> None:
+    """Until the native backend lands, ESP8266 serves only PlatformIO."""
+    from esphome.components.esp8266 import CONFIG_SCHEMA
+
+    CORE.toolchain = Toolchain.ARDUINO
+    with pytest.raises(cv.Invalid, match="Unsupported toolchain 'arduino'"):
+        CONFIG_SCHEMA({"board": "nodemcuv2"})
@@ -1,65 +0,0 @@
-"""Run the native-toolchain serial-upload path and report heavy modules.
-
-Executed as a subprocess by test_lazy_imports.py: heavy module names come
-in on argv, the ones found in sys.modules afterwards go out on stdout.
-``upload_using_esptool`` dispatches native toolchains through a
-toolchain-keyed table; if someone routes it back through the platform
-component packages (esp32 or esp8266), this reports the leak.
-"""
-
-import os
-from pathlib import Path
-import sys
-import tempfile
-from unittest.mock import patch
-
-from _leak_report import print_leaked_modules
-
-from esphome.__main__ import upload_using_esptool
-from esphome.const import (
-    CONF_ESPHOME,
-    KEY_CORE,
-    KEY_ESP32,
-    KEY_TARGET_PLATFORM,
-    KEY_VARIANT,
-    Toolchain,
-)
-from esphome.core import CORE
-
-# An ambient ESPHOME_USE_SUBPROCESS would route past the patched
-# run_external_command into run_external_process and confuse the checks.
-os.environ.pop("ESPHOME_USE_SUBPROCESS", None)
-
-config = {CONF_ESPHOME: {"platformio_options": {}}}
-
-with tempfile.TemporaryDirectory() as build_dir:
-    CORE.name = "leaktest"
-    CORE.build_path = build_dir
-
-    for platform, toolchain, backend in (
-        ("esp8266", Toolchain.ARDUINO, "esphome.arduino8266.toolchain"),
-        ("esp32", Toolchain.ESP_IDF, "esphome.espidf.toolchain"),
-    ):
-        CORE.data[KEY_CORE] = {KEY_TARGET_PLATFORM: platform}
-        if platform == "esp32":
-            CORE.data[KEY_ESP32] = {KEY_VARIANT: "ESP32S3"}
-        CORE.toolchain = toolchain
-
-        import importlib
-
-        image = importlib.import_module(backend).get_factory_firmware_path()
-        image.parent.mkdir(parents=True, exist_ok=True)
-        image.write_bytes(b"\x00")
-
-        with patch("esphome.__main__.run_external_command", return_value=0) as mock_run:
-            rc = upload_using_esptool(config, "/dev/ttyUSB0", None, None)
-
-        # Fail loudly if the upload path stopped doing its work; otherwise
-        # an empty leak list could just mean nothing ran.
-        if rc != 0:
-            sys.exit(f"upload_using_esptool({platform}) returned {rc}")
-        cmd = list(mock_run.call_args[0][1:])
-        if str(image) not in [str(Path(c)) for c in cmd]:
-            sys.exit(f"native factory image did not reach esptool: {cmd}")
-
-print_leaked_modules()
@@ -1,631 +0,0 @@
-"""Tests for esphome.arduino8266.toolchain (the ninja build driver)."""
-
-from __future__ import annotations
-
-import os
-from pathlib import Path
-from unittest.mock import MagicMock, patch
-
-import pytest
-
-from esphome.arduino8266 import framework, toolchain
-import esphome.config_validation as cv
-from esphome.const import (
-    CONF_COMPILE_PROCESS_LIMIT,
-    CONF_ESPHOME,
-    KEY_CORE,
-    KEY_FRAMEWORK_VERSION,
-)
-from esphome.core import CORE, EsphomeError
-
-_SIZE_OUTPUT = """\
-firmware.elf  :
-section       size    addr
-.data         1924    1073643520
-.noinit       56      1073645444
-.text         496     1074790400
-.irom0.text   342804  1075843088
-.text1        27489   1074790896
-.rodata       2588    1073645504
-.bss          26504   1073648096
-Total         401861
-"""
-
-
-@pytest.fixture(autouse=True)
-def _setup_core(tmp_path: Path) -> None:
-    CORE.name = "test8266"
-    CORE.config_path = tmp_path / "test8266.yaml"
-    CORE.build_path = tmp_path
-    CORE.data[KEY_CORE] = {KEY_FRAMEWORK_VERSION: cv.Version(3, 1, 2)}
-    # run_compile verifies the produced artifacts; give every test a build
-    # that "produced" them (tests for the guard delete them again). The
-    # manifest comes first: artifacts must not be older than build.ninja.
-    build_dir = CORE.relative_pioenvs_path("test8266")
-    build_dir.mkdir(parents=True, exist_ok=True)
-    (build_dir / "build.ninja").write_text("# manifest")
-    for artifact in (
-        "firmware.elf",
-        "firmware.bin",
-        "firmware.factory.bin",
-        "firmware.ota.bin",
-    ):
-        (build_dir / artifact).write_bytes(b"")
-
-
-def _paths(tmp_path: Path) -> framework.InstalledPaths:
-    return framework.InstalledPaths(
-        framework=tmp_path / "framework",
-        toolchain=tmp_path / "toolchain",
-        ninja=tmp_path / "ninja",
-    )
-
-
-def test_path_getters(tmp_path: Path) -> None:
-    assert toolchain.get_build_dir() == CORE.relative_pioenvs_path("test8266")
-    assert toolchain.get_elf_path().name == "firmware.elf"
-    # The framework accessor owns the layout and the Windows suffix
-    suffix = ".exe" if os.name == "nt" else ""
-    assert toolchain.get_addr2line_path().name == f"xtensa-lx106-elf-addr2line{suffix}"
-    assert toolchain.get_objdump_path().name == f"xtensa-lx106-elf-objdump{suffix}"
-    assert toolchain.get_readelf_path().name == f"xtensa-lx106-elf-readelf{suffix}"
-
-
-def test_run_compile_build_failure(tmp_path: Path) -> None:
-    with (
-        patch.object(framework, "check_and_install", return_value=_paths(tmp_path)),
-        patch.object(framework, "get_build_env", return_value={}),
-        patch("esphome.build_gen.arduino8266.write_project"),
-        patch.object(
-            toolchain.subprocess, "run", return_value=MagicMock(returncode=2)
-        ) as mock_run,
-        patch.object(toolchain, "_write_compile_commands") as mock_compdb,
-    ):
-        assert toolchain.run_compile({CONF_ESPHOME: {}}, verbose=True) == 2
-    cmd = mock_run.call_args[0][0]
-    assert "-v" in cmd
-    # The compile database is generated before the build runs, so a failed
-    # build cannot leave a stale database behind.
-    mock_compdb.assert_called_once()
-
-
-def test_run_compile_success(tmp_path: Path) -> None:
-    with (
-        patch.object(framework, "check_and_install", return_value=_paths(tmp_path)),
-        patch.object(framework, "get_build_env", return_value={}),
-        # An unchanged manifest is what makes the -n probe run
-        patch("esphome.build_gen.arduino8266.write_project", return_value=False),
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(returncode=0, stdout="", stderr=""),
-        ) as mock_run,
-        patch.object(toolchain, "_write_compile_commands") as mock_compdb,
-        patch.object(toolchain, "_print_size_summary") as mock_size,
-        patch.object(toolchain, "get_idedata") as mock_idedata,
-    ):
-        rc = toolchain.run_compile(
-            {CONF_ESPHOME: {CONF_COMPILE_PROCESS_LIMIT: 4}}, verbose=False
-        )
-    assert rc == 0
-    # The -n probe runs first, then the real build (cwd, no -C banner)
-    ninja_calls = [c for c in mock_run.call_args_list if "ninja" in str(c[0][0][0])]
-    assert "-n" in ninja_calls[0][0][0]
-    # Explicit targets: a manifest missing them fails as "unknown target"
-    assert ninja_calls[0][0][0][-1] == "firmware.ota.bin"
-    cmd = ninja_calls[1][0][0]
-    assert cmd[-4:] == ["-j", "4", "firmware.factory.bin", "firmware.ota.bin"]
-    assert "-C" not in cmd
-    assert ninja_calls[1][1]["cwd"] is not None
-    mock_compdb.assert_called_once()
-    mock_size.assert_called_once()
-    mock_idedata.assert_called_once()
-
-
-def test_run_compile_noop_skips_the_build_spawn(tmp_path: Path) -> None:
-    """A no-op rebuild stays quiet: the -n probe answers "no work to do"
-    and the real ninja spawn (and its banner) never happens."""
-    with (
-        patch.object(framework, "check_and_install", return_value=_paths(tmp_path)),
-        patch.object(framework, "get_build_env", return_value={}),
-        # An unchanged manifest is what makes the -n probe run
-        patch("esphome.build_gen.arduino8266.write_project", return_value=False),
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(
-                returncode=0, stdout="ninja: no work to do.\n", stderr=""
-            ),
-        ) as mock_run,
-        patch.object(toolchain, "_write_compile_commands"),
-        patch.object(toolchain, "_print_size_summary"),
-        patch.object(toolchain, "get_idedata"),
-    ):
-        rc = toolchain.run_compile({CONF_ESPHOME: {}}, verbose=False)
-    assert rc == 0
-    ninja_calls = [c for c in mock_run.call_args_list if "ninja" in str(c[0][0][0])]
-    assert len(ninja_calls) == 1
-    assert "-n" in ninja_calls[0][0][0]
-    # Explicit targets: a manifest missing them fails as "unknown target"
-    assert ninja_calls[0][0][0][-1] == "firmware.ota.bin"
-
-
-def test_run_compile_regenerates_stale_compdb(tmp_path: Path) -> None:
-    """An interrupted run can leave build.ninja newer than the compile DB;
-    mere existence must not skip regeneration."""
-    build_dir = toolchain.get_build_dir()
-    build_dir.mkdir(parents=True, exist_ok=True)
-    (build_dir / "build.ninja").write_text("")
-    compdb = build_dir / "compile_commands.json"
-    compdb.write_text("[]")
-    os.utime(compdb, ((build_dir / "build.ninja").stat().st_mtime - 5,) * 2)
-    with (
-        patch.object(framework, "check_and_install", return_value=_paths(tmp_path)),
-        patch.object(framework, "get_build_env", return_value={}),
-        patch("esphome.build_gen.arduino8266.write_project", return_value=False),
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(
-                returncode=0, stdout="ninja: no work to do.\n", stderr=""
-            ),
-        ),
-        patch.object(toolchain, "_write_compile_commands") as mock_compdb,
-        patch.object(toolchain, "_print_size_summary"),
-        patch.object(toolchain, "get_idedata"),
-    ):
-        assert toolchain.run_compile({CONF_ESPHOME: {}}, verbose=False) == 0
-    mock_compdb.assert_called_once()
-
-
-def test_run_compile_surfaces_probe_diagnostics(
-    tmp_path: Path, caplog: pytest.LogCaptureFixture
-) -> None:
-    """A load-time ninja diagnostic (a generator bug signal) reaches the
-    user even when the no-work branch skips the real spawn."""
-    with (
-        patch.object(framework, "check_and_install", return_value=_paths(tmp_path)),
-        patch.object(framework, "get_build_env", return_value={}),
-        # An unchanged manifest is what makes the -n probe run
-        patch("esphome.build_gen.arduino8266.write_project", return_value=False),
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(
-                returncode=0,
-                stdout="ninja: no work to do.\n",
-                stderr="ninja: warning: multiple rules generate x\n",
-            ),
-        ),
-        patch.object(toolchain, "_write_compile_commands"),
-        patch.object(toolchain, "_print_size_summary"),
-        patch.object(toolchain, "get_idedata"),
-    ):
-        rc = toolchain.run_compile({CONF_ESPHOME: {}}, verbose=False)
-    assert rc == 0
-    assert "multiple rules generate x" in caplog.text
-
-
-def test_run_compile_missing_artifact_fails(
-    tmp_path: Path, caplog: pytest.LogCaptureFixture
-) -> None:
-    """A zero ninja exit that produced no firmware must not be a green
-    build (size summary and idedata only warn)."""
-    (toolchain.get_build_dir() / "firmware.elf").unlink()
-    with (
-        patch.object(framework, "check_and_install", return_value=_paths(tmp_path)),
-        patch.object(framework, "get_build_env", return_value={}),
-        patch("esphome.build_gen.arduino8266.write_project"),
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(returncode=0, stdout="", stderr=""),
-        ),
-        patch.object(toolchain, "_write_compile_commands"),
-        patch.object(toolchain, "_print_size_summary") as mock_size,
-        patch.object(toolchain, "get_idedata"),
-    ):
-        rc = toolchain.run_compile({CONF_ESPHOME: {}}, verbose=False)
-    assert rc == 1
-    assert "Build produced no" in caplog.text
-    mock_size.assert_not_called()
-
-
-def test_run_compile_warns_when_idedata_fails(
-    tmp_path: Path, caplog: pytest.LogCaptureFixture
-) -> None:
-    """A failed idedata generation right after a successful build is visible,
-    not deferred to a misleading error in a later command."""
-    with (
-        patch.object(framework, "check_and_install", return_value=_paths(tmp_path)),
-        patch.object(framework, "get_build_env", return_value={}),
-        patch("esphome.build_gen.arduino8266.write_project"),
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(returncode=0, stdout="", stderr=""),
-        ),
-        patch.object(toolchain, "_write_compile_commands"),
-        patch.object(toolchain, "_print_size_summary"),
-        patch.object(toolchain, "get_idedata", return_value=None),
-    ):
-        assert toolchain.run_compile({CONF_ESPHOME: {}}, verbose=False) == 0
-    assert "No idedata was generated for this build" in caplog.text
-
-
-def test_write_compile_commands(tmp_path: Path) -> None:
-    build_dir = tmp_path / "build"
-    build_dir.mkdir()
-    entries = '[{"file": "a.cpp", "command": "cc"}]\n'
-    with patch.object(
-        toolchain.subprocess,
-        "run",
-        return_value=MagicMock(returncode=0, stdout=entries),
-    ):
-        toolchain._write_compile_commands(tmp_path / "ninja", build_dir, {})
-    assert (build_dir / "compile_commands.json").read_text() == entries
-
-
-@pytest.mark.parametrize(
-    ("stdout", "match"),
-    [
-        ("[]\n", "empty compile database"),
-        # A parse failure names its cause, not the rule-name story
-        ("not json", "unparsable compile database.*not json"),
-    ],
-)
-def test_write_compile_commands_bad_db_raises(
-    tmp_path: Path, stdout: str, match: str
-) -> None:
-    """An empty or unparsable compile database fails the build with its
-    actual cause and drops any stale database."""
-    build_dir = tmp_path / "build"
-    build_dir.mkdir()
-    (build_dir / "compile_commands.json").write_text("[stale]")
-    with (
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(returncode=0, stdout=stdout),
-        ),
-        pytest.raises(EsphomeError, match=match),
-    ):
-        toolchain._write_compile_commands(tmp_path / "ninja", build_dir, {})
-    assert not (build_dir / "compile_commands.json").exists()
-
-
-def test_write_compile_commands_failure_removes_stale_db(tmp_path: Path) -> None:
-    """A failed compdb run must not leave a stale database behind."""
-    stale = tmp_path / "compile_commands.json"
-    stale.write_text("[]")
-    with (
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(returncode=1, stderr="boom"),
-        ),
-        pytest.raises(EsphomeError, match="compile_commands"),
-    ):
-        toolchain._write_compile_commands(tmp_path / "ninja", tmp_path, {})
-    assert not stale.exists()
-
-
-def test_parse_app_size(tmp_path: Path) -> None:
-    ld = tmp_path / "eagle.flash.4m.ld"
-    ld.write_text("MEMORY\n{\n  irom0_0_seg :  org = 0x40201010, len = 0xfeff0\n}\n")
-    with patch("esphome.build_gen.arduino8266.get_flash_ld_path", return_value=ld):
-        assert toolchain._parse_app_size(tmp_path, _paths(tmp_path)) == 0xFEFF0
-
-    ld.write_text("MEMORY { }\n")
-    with patch("esphome.build_gen.arduino8266.get_flash_ld_path", return_value=ld):
-        assert toolchain._parse_app_size(tmp_path, _paths(tmp_path)) is None
-
-    # A zero-length segment is bad data, not a budget; warn and drop it
-    ld.write_text("MEMORY\n{\n  irom0_0_seg :  org = 0x40201010, len = 0x0\n}\n")
-    with patch("esphome.build_gen.arduino8266.get_flash_ld_path", return_value=ld):
-        assert toolchain._parse_app_size(tmp_path, _paths(tmp_path)) is None
-
-    with patch(
-        "esphome.build_gen.arduino8266.get_flash_ld_path",
-        return_value=tmp_path / "missing.ld",
-    ):
-        assert toolchain._parse_app_size(tmp_path, _paths(tmp_path)) is None
-
-
-def test_print_size_summary(tmp_path: Path, capsys: pytest.CaptureFixture[str]) -> None:
-    with (
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(returncode=0, stdout=_SIZE_OUTPUT),
-        ),
-        patch.object(toolchain, "_parse_app_size", return_value=1044464),
-    ):
-        toolchain._print_size_summary(tmp_path, _paths(tmp_path))
-    out = capsys.readouterr().out
-    # Exact PlatformIO shape so script/ci_memory_impact_extract.py can parse it
-    assert "RAM:   [====      ]  37.9% (used 31016 bytes from 81920 bytes)" in out
-    assert "Flash: [====      ]  35.9% (used 375301 bytes from 1044464 bytes)" in out
-
-
-def test_print_size_summary_missing_size_tool_warns(
-    tmp_path: Path, caplog: pytest.LogCaptureFixture
-) -> None:
-    """A missing size binary degrades to a warning; the firmware already
-    linked and must not be discarded."""
-    with patch.object(
-        toolchain.subprocess, "run", side_effect=FileNotFoundError("no size")
-    ):
-        toolchain._print_size_summary(tmp_path, _paths(tmp_path))
-    assert "Could not summarize firmware size" in caplog.text
-
-
-def test_print_size_summary_no_app_size(
-    tmp_path: Path, capsys: pytest.CaptureFixture[str]
-) -> None:
-    with (
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(returncode=0, stdout=_SIZE_OUTPUT),
-        ),
-        patch.object(toolchain, "_parse_app_size", return_value=None),
-    ):
-        toolchain._print_size_summary(tmp_path, _paths(tmp_path))
-    out = capsys.readouterr().out
-    # Both lines are skipped together: a RAM line without Flash would skew
-    # CI's memory-impact sums across builds
-    assert out == ""
-
-
-def test_print_size_summary_size_tool_failure(
-    tmp_path: Path,
-    capsys: pytest.CaptureFixture[str],
-    caplog: pytest.LogCaptureFixture,
-) -> None:
-    with patch.object(
-        toolchain.subprocess,
-        "run",
-        return_value=MagicMock(returncode=1, stdout="", stderr="bad elf"),
-    ):
-        toolchain._print_size_summary(tmp_path, _paths(tmp_path))
-    assert capsys.readouterr().out == ""
-    assert "Could not summarize firmware size" in caplog.text
-
-
-def test_get_idedata_delegates(tmp_path: Path) -> None:
-    with (
-        patch(
-            "esphome.build_helpers.idedata.load_or_build_idedata",
-            return_value={"cc_path": "x"},
-        ) as mock_load,
-        patch.object(toolchain, "resolve_ccache_path", return_value="/cc/ccache"),
-    ):
-        assert toolchain.get_idedata() == {"cc_path": "x"}
-    compile_commands, elf, cache = mock_load.call_args[0]
-    assert compile_commands.name == "compile_commands.json"
-    assert elf.name == "firmware.elf"
-    assert cache.name == "test8266.arduino.json"
-    # The exact configured launcher string is passed for compile DB parsing
-    # (resolve_ccache_path returns a str, untouched on every platform)
-    assert mock_load.call_args.kwargs["launcher"] == "/cc/ccache"
-
-
-def test_get_idedata_no_ccache(tmp_path: Path) -> None:
-    with (
-        patch(
-            "esphome.build_helpers.idedata.load_or_build_idedata", return_value={}
-        ) as mock_load,
-        patch.object(toolchain, "resolve_ccache_path", return_value=None),
-    ):
-        toolchain.get_idedata()
-    assert mock_load.call_args.kwargs["launcher"] is None
-
-
-def test_run_compile_skips_compdb_when_ninja_unchanged(tmp_path: Path) -> None:
-    """An unchanged build.ninja means the compile DB is already current."""
-    build_dir = toolchain.get_build_dir()
-    build_dir.mkdir(parents=True, exist_ok=True)
-    # write_project (stubbed below) always leaves a build.ninja behind
-    (build_dir / "build.ninja").write_text("# manifest")
-
-    def run(regenerate_expected: bool) -> None:
-        with (
-            patch.object(framework, "check_and_install", return_value=_paths(tmp_path)),
-            patch.object(framework, "get_build_env", return_value={}),
-            patch("esphome.build_gen.arduino8266.write_project", return_value=False),
-            patch.object(
-                toolchain.subprocess,
-                "run",
-                return_value=MagicMock(returncode=0, stdout="", stderr=""),
-            ),
-            patch.object(toolchain, "_write_compile_commands") as mock_compdb,
-            patch.object(toolchain, "_print_size_summary"),
-            patch.object(toolchain, "get_idedata"),
-        ):
-            assert toolchain.run_compile({CONF_ESPHOME: {}}, verbose=False) == 0
-        assert mock_compdb.called == regenerate_expected
-
-    # Missing compile DB: regenerated even though build.ninja is unchanged
-    run(regenerate_expected=True)
-    # Present compile DB + unchanged build.ninja: skipped
-    (build_dir / "compile_commands.json").write_text("[]")
-    run(regenerate_expected=False)
-
-
-def test_print_size_summary_unparsable_section(
-    tmp_path: Path,
-    capsys: pytest.CaptureFixture[str],
-    caplog: pytest.LogCaptureFixture,
-) -> None:
-    """A totals-relevant section that fails to parse must not produce a
-    confident wrong number; an irrelevant one only warns."""
-    bad = _SIZE_OUTPUT.replace(".bss          26504", ".bss          abc")
-    with patch.object(
-        toolchain.subprocess,
-        "run",
-        return_value=MagicMock(returncode=0, stdout=bad),
-    ):
-        toolchain._print_size_summary(tmp_path, _paths(tmp_path))
-    assert capsys.readouterr().out == ""
-    assert "Unparsable size output" in caplog.text
-
-    caplog.clear()
-    harmless = _SIZE_OUTPUT + ".broken   abc   0\n"
-    with (
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(returncode=0, stdout=harmless),
-        ),
-        patch.object(toolchain, "_parse_app_size", return_value=1044464),
-    ):
-        toolchain._print_size_summary(tmp_path, _paths(tmp_path))
-    assert "RAM:" in capsys.readouterr().out
-    assert "Unparsable size output" in caplog.text
-
-
-def test_print_size_summary_missing_section_skips_summary(
-    tmp_path: Path,
-    capsys: pytest.CaptureFixture[str],
-    caplog: pytest.LogCaptureFixture,
-) -> None:
-    """A totals section absent from the output must not default to zero."""
-    without_bss = "\n".join(
-        line for line in _SIZE_OUTPUT.splitlines() if ".bss" not in line
-    )
-    with patch.object(
-        toolchain.subprocess,
-        "run",
-        return_value=MagicMock(returncode=0, stdout=without_bss),
-    ):
-        toolchain._print_size_summary(tmp_path, _paths(tmp_path))
-    assert capsys.readouterr().out == ""
-    assert "missing section(s) .bss" in caplog.text
-
-
-def test_warn_ignored_platformio_options(caplog: pytest.LogCaptureFixture) -> None:
-    """Component-added options the native build drops are warned by name;
-    the honored ones (lib_ignore, f_cpu, ldscript, build_src_flags,
-    flash_mode) stay quiet."""
-    CORE.platformio_options = {
-        "board_build.ldscript": "eagle.flash.4m2m.ld",
-        "board_build.f_cpu": "160000000L",
-        "board_build.filesystem": "littlefs",
-        "board_build.flash_mode": "dio",
-        "build_src_flags": "-include throw_stubs.h",
-        "lib_ignore": ["Updater"],
-        "upload_speed": "460800",
-    }
-    toolchain._warn_ignored_platformio_options()
-    assert "platformio_options->board_build.filesystem is ignored" in caplog.text
-    assert "native 'arduino' toolchain" in caplog.text
-    assert "board_build.ldscript is ignored" not in caplog.text
-    assert "board_build.f_cpu is ignored" not in caplog.text
-    assert "lib_ignore" not in caplog.text
-    assert "build_src_flags" not in caplog.text
-    assert "flash_mode" not in caplog.text
-    # Component-added upload_speed never gets read under the native
-    # toolchain, so it must warn
-    assert "upload_speed" in caplog.text
-
-
-def test_run_compile_idedata_error_does_not_fail_build(
-    tmp_path: Path, caplog: pytest.LogCaptureFixture
-) -> None:
-    """An unusable compile DB after a successful build warns, never fails."""
-    with (
-        patch.object(framework, "check_and_install", return_value=_paths(tmp_path)),
-        patch.object(framework, "get_build_env", return_value={}),
-        patch("esphome.build_gen.arduino8266.write_project"),
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(returncode=0, stdout="", stderr=""),
-        ),
-        patch.object(toolchain, "_write_compile_commands"),
-        patch.object(toolchain, "_print_size_summary"),
-        patch.object(
-            toolchain,
-            "get_idedata",
-            side_effect=EsphomeError("compile database is unusable"),
-        ),
-    ):
-        assert toolchain.run_compile({CONF_ESPHOME: {}}, verbose=False) == 0
-    assert "Could not generate idedata: compile database is unusable" in caplog.text
-
-
-def test_run_compile_skipped_size_summary_names_consequence(
-    tmp_path: Path, caplog: pytest.LogCaptureFixture
-) -> None:
-    """A skipped RAM/Flash summary warns about the missing metric; the
-    per-cause warnings alone are invisible to CI harnesses."""
-    with (
-        patch.object(framework, "check_and_install", return_value=_paths(tmp_path)),
-        patch.object(framework, "get_build_env", return_value={}),
-        patch("esphome.build_gen.arduino8266.write_project"),
-        patch.object(
-            toolchain.subprocess,
-            "run",
-            return_value=MagicMock(returncode=0, stdout="", stderr=""),
-        ),
-        patch.object(toolchain, "_write_compile_commands"),
-        patch.object(toolchain, "_print_size_summary", return_value=False),
-        patch.object(toolchain, "get_idedata", return_value=None),
-    ):
-        assert toolchain.run_compile({CONF_ESPHOME: {}}, verbose=False) == 0
-    assert "Firmware size summary unavailable for this build" in caplog.text
-
-
-def test_parse_app_size_non_utf8_ld_warns(
-    tmp_path: Path, caplog: pytest.LogCaptureFixture
-) -> None:
-    """A corrupt (non-UTF-8) linker script degrades to the same warning as
-    an unreadable one, never a traceback after a successful link."""
-    paths = _paths(tmp_path)
-    ld = tmp_path / "corrupt.ld"
-    ld.write_bytes(b"\xff\xfe not utf8")
-    with patch("esphome.build_gen.arduino8266.get_flash_ld_path", return_value=ld):
-        assert toolchain._parse_app_size(tmp_path, paths) is None
-    assert "Cannot read linker script" in caplog.text
-
-
-def test_run_compile_failed_probe_runs_full_build(tmp_path: Path) -> None:
-    """A failing -n probe (e.g. unknown target from a defective manifest)
-    falls through to the real build so the error prints attributably."""
-    probe = MagicMock(returncode=1, stdout="", stderr="")
-    ok = MagicMock(returncode=0, stdout="", stderr="")
-
-    def fake_run(cmd, *args, **kwargs):
-        return probe if "-n" in cmd else ok
-
-    with (
-        patch.object(framework, "check_and_install", return_value=_paths(tmp_path)),
-        patch.object(framework, "get_build_env", return_value={}),
-        patch("esphome.build_gen.arduino8266.write_project", return_value=False),
-        patch.object(toolchain.subprocess, "run", side_effect=fake_run) as mock_run,
-        patch.object(toolchain, "_write_compile_commands"),
-        patch.object(toolchain, "_print_size_summary", return_value=True),
-        patch.object(toolchain, "get_idedata", return_value={}),
-    ):
-        assert toolchain.run_compile({CONF_ESPHOME: {}}, verbose=False) == 0
-    # The real build ran after the failed probe
-    assert any(
-        "firmware.ota.bin" in c[0][0] and "-n" not in c[0][0]
-        for c in mock_run.call_args_list
-    )
-
-
-def test_get_idedata_accepts_preresolved_ccache() -> None:
-    """run_compile threads its resolved ccache through; the probe must not
-    run again."""
-    with (
-        patch(
-            "esphome.build_helpers.idedata.load_or_build_idedata",
-            return_value={"ok": True},
-        ) as mock_build,
-        patch.object(toolchain, "resolve_ccache_path") as mock_resolve,
-    ):
-        assert toolchain.get_idedata("/usr/bin/ccache") == {"ok": True}
-    mock_resolve.assert_not_called()
-    assert mock_build.call_args.kwargs["launcher"] == "/usr/bin/ccache"
@@ -175,27 +175,6 @@ def test_esptool_upload_fast_path_does_not_import_heavy_modules(
    )


-def test_native_upload_fast_path_does_not_import_heavy_modules(
-    fixture_path: Path,
-    probe_env: dict[str, str],
-) -> None:
-    """The native-toolchain serial upload dispatches through a
-    toolchain-keyed backend table; resolving the flash image must not drag
-    in the esp32 or esp8266 component package or the validation stack.
-    """
-    leaked = _leaked_from_fixture(
-        fixture_path,
-        probe_env,
-        "native_upload_fast_path.py",
-        extra=("esphome.components.esp8266",),
-    )
-    assert not leaked, (
-        f"native upload_using_esptool pulls in heavy modules: {leaked}. "
-        "The upload fast path skips validation; importing a platform "
-        "component package executes its codegen module by design."
-    )
-
-
 def test_api_client_does_not_import_heavy_modules() -> None:
    """``esphome.api_client`` is on the logs fast path and must stay light.

@@ -13,7 +13,7 @@ import sys
 import time
 from types import SimpleNamespace
 from typing import Any, Self
-from unittest.mock import AsyncMock, MagicMock, Mock, PropertyMock, patch
+from unittest.mock import AsyncMock, MagicMock, Mock, patch

 import pytest
 from pytest import CaptureFixture
@@ -25,7 +25,6 @@ from esphome.__main__ import (
    Purpose,
    _get_configured_xtal_freq,
    _make_crystal_freq_callback,
-    _native_toolchain_module,
    _redact_with_legacy_fallback,
    _resolve_network_devices,
    _should_subscribe_states,
@@ -7133,7 +7132,7 @@ def test_command_run_rp2040_bootsel_redetects_serial_port() -> None:

 def test_command_idedata_esp_idf_prints_json(capsys: CaptureFixture) -> None:
    """Under the native ESP-IDF toolchain, idedata is emitted as JSON."""
-    setup_core(platform=PLATFORM_ESP32)
+    setup_core()
    CORE.toolchain = Toolchain.ESP_IDF
    data = {"cxx_path": "g++", "prog_path": "/build/firmware.elf"}

@@ -7147,7 +7146,7 @@ def test_command_idedata_esp_idf_prints_json(capsys: CaptureFixture) -> None:

 def test_command_idedata_esp_idf_no_build_errors() -> None:
    """Under ESP-IDF, a missing build (no idedata) returns an error, not a crash."""
-    setup_core(platform=PLATFORM_ESP32)
+    setup_core()
    CORE.toolchain = Toolchain.ESP_IDF

    with patch("esphome.espidf.toolchain.get_idedata", return_value=None):
@@ -7321,201 +7320,6 @@ def test_warn_source_tree_mismatch_falls_back_when_stat_fails(
    assert not caplog.text


-def test_upload_using_esptool_arduino_toolchain(
-    tmp_path: Path,
-    mock_run_external_command_main: Mock,
-) -> None:
-    """The native ESP8266 Arduino toolchain flashes its factory image at
-    0x0, resolved from the toolchain-keyed backend table (deliberately not
-    the platform hook: that import would break the upload fast path)."""
-    setup_core(platform=PLATFORM_ESP8266, tmp_path=tmp_path, name="test")
-    CORE.toolchain = Toolchain.ARDUINO
-    from esphome.arduino8266 import toolchain as native
-
-    factory = native.get_factory_firmware_path()
-    factory.parent.mkdir(parents=True, exist_ok=True)
-    factory.touch()
-
-    config = {CONF_ESPHOME: {"platformio_options": {}}}
-    result = upload_using_esptool(config, "/dev/ttyUSB0", None, None)
-
-    assert result == 0
-    cmd_list = list(mock_run_external_command_main.call_args[0][1:])
-    firmware_offset_idx = cmd_list.index("write-flash") + 4
-    assert cmd_list[firmware_offset_idx] == "0x0"
-    assert cmd_list[firmware_offset_idx + 1] == str(factory)
-
-
-@pytest.mark.parametrize(
-    ("toolchain", "pio_project_written"),
-    [
-        # The native toolchain generates its project at compile time, so
-        # write_cpp_file must not write a platformio.ini; the default
-        # toolchain writes the PlatformIO project files.
-        (Toolchain.ARDUINO, False),
-        (None, True),
-    ],
-)
-def test_write_cpp_file_project_generation_follows_toolchain(
-    tmp_path: Path, toolchain: Toolchain | None, pio_project_written: bool
-) -> None:
-    setup_core(platform=PLATFORM_ESP8266, tmp_path=tmp_path, name="test")
-    CORE.toolchain = toolchain
-
-    with (
-        patch("esphome.writer.write_cpp") as mock_write_cpp,
-        patch("esphome.build_gen.platformio.write_project") as mock_pio_project,
-        patch.object(
-            type(CORE), "cpp_main_section", new_callable=PropertyMock
-        ) as mock_section,
-    ):
-        mock_section.return_value = ""
-        assert main.write_cpp_file() == 0
-
-    mock_write_cpp.assert_called_once()
-    assert mock_pio_project.called is pio_project_written
-
-
-def test_command_idedata_arduino_prints_json(
-    tmp_path: Path, capsys: CaptureFixture
-) -> None:
-    """Under the native ESP8266 Arduino toolchain, idedata is emitted as JSON."""
-    setup_core(platform=PLATFORM_ESP8266, tmp_path=tmp_path)
-    CORE.toolchain = Toolchain.ARDUINO
-    data = {"cxx_path": "g++", "prog_path": "/build/firmware.elf"}
-
-    with patch(
-        "esphome.arduino8266.toolchain.get_idedata", return_value=data
-    ) as mock_get:
-        result = command_idedata(MagicMock(), CORE.config)
-
-    assert result == 0
-    mock_get.assert_called_once_with()
-    assert json.loads(capsys.readouterr().out) == data
-
-
-def test_command_idedata_arduino_no_build_errors(tmp_path: Path) -> None:
-    """A missing native build (no idedata) returns an error, not a crash."""
-    setup_core(platform=PLATFORM_ESP8266, tmp_path=tmp_path)
-    CORE.toolchain = Toolchain.ARDUINO
-
-    with patch("esphome.arduino8266.toolchain.get_idedata", return_value=None):
-        result = command_idedata(MagicMock(), CORE.config)
-
-    assert result == 1
-
-
-@pytest.mark.parametrize(
-    ("platform", "toolchain", "module"),
-    [
-        (PLATFORM_ESP8266, Toolchain.ARDUINO, "esphome.arduino8266.toolchain"),
-        (PLATFORM_ESP32, Toolchain.ESP_IDF, "esphome.espidf.toolchain"),
-    ],
-)
-def test_command_analyze_memory_native_toolchains(
-    tmp_path: Path,
-    mock_write_cpp: Mock,
-    mock_compile_program: Mock,
-    mock_get_esphome_components: Mock,
-    mock_memory_analyzer_cli: Mock,
-    mock_ram_strings_analyzer: Mock,
-    platform: str,
-    toolchain: Toolchain,
-    module: str,
-) -> None:
-    """analyze-memory uses the native toolchain's binutils instead of
-    falling into the PlatformIO branch."""
-    setup_core(platform=platform, tmp_path=tmp_path, name="test_device")
-    CORE.toolchain = toolchain
-
-    config = {CONF_ESPHOME: {CONF_NAME: "test_device"}}
-    # The tools must exist: a missing binutils now fails by name instead of
-    # silently falling back to host tools
-    objdump = tmp_path / "objdump"
-    readelf = tmp_path / "readelf"
-    objdump.write_text("")
-    readelf.write_text("")
-    # The ELF must exist too: the analyzer swallows tool failures, so a
-    # missing image would report zeroes with exit 0
-    firmware_elf = tmp_path / "firmware.elf"
-    firmware_elf.write_text("")
-    with (
-        patch(f"{module}.get_objdump_path", return_value=objdump),
-        patch(f"{module}.get_readelf_path", return_value=readelf),
-        patch(f"{module}.get_elf_path", return_value=firmware_elf),
-    ):
-        result = command_analyze_memory(MockArgs(), config)
-
-    assert result == 0
-    mock_memory_analyzer_cli.assert_called_once_with(
-        str(firmware_elf),
-        str(objdump),
-        str(readelf),
-        set(),
-        idedata=None,
-    )
-
-
-def test_command_analyze_memory_native_missing_elf_fails(
-    tmp_path: Path,
-    mock_write_cpp: Mock,
-    mock_compile_program: Mock,
-    mock_get_esphome_components: Mock,
-    mock_memory_analyzer_cli: Mock,
-    mock_ram_strings_analyzer: Mock,
-    caplog: pytest.LogCaptureFixture,
-) -> None:
-    """A missing firmware.elf fails by name instead of an exit-0 zeroed
-    report."""
-    setup_core(platform=PLATFORM_ESP8266, tmp_path=tmp_path, name="test_device")
-    CORE.toolchain = Toolchain.ARDUINO
-
-    config = {CONF_ESPHOME: {CONF_NAME: "test_device"}}
-    objdump = tmp_path / "objdump"
-    readelf = tmp_path / "readelf"
-    objdump.write_text("")
-    readelf.write_text("")
-    module = "esphome.arduino8266.toolchain"
-    with (
-        patch(f"{module}.get_objdump_path", return_value=objdump),
-        patch(f"{module}.get_readelf_path", return_value=readelf),
-        patch(f"{module}.get_elf_path", return_value=tmp_path / "missing.elf"),
-    ):
-        result = command_analyze_memory(MockArgs(), config)
-
-    assert result == 1
-    assert "compile the configuration first" in caplog.text
-    mock_memory_analyzer_cli.assert_not_called()
-
-
-def test_command_analyze_memory_missing_binutils_fails_by_name(
-    tmp_path: Path, caplog: pytest.LogCaptureFixture
-) -> None:
-    """A truncated toolchain install fails naming the missing tool instead
-    of silently analyzing with host binutils."""
-    setup_core(platform="esp8266", tmp_path=tmp_path, name="test_device")
-    CORE.toolchain = Toolchain.ARDUINO
-    config = {CONF_ESPHOME: {CONF_NAME: "test_device"}}
-    module = "esphome.arduino8266.toolchain"
-    with (
-        patch(f"{module}.get_objdump_path", return_value=tmp_path / "missing-objdump"),
-        patch(f"{module}.get_readelf_path", return_value=tmp_path / "readelf"),
-        patch("esphome.__main__.write_cpp", return_value=0),
-        patch("esphome.__main__.compile_program", return_value=0),
-    ):
-        assert command_analyze_memory(MockArgs(), config) == 1
-    assert "missing-objdump" in caplog.text
-    assert "toolchain install may be incomplete" in caplog.text
-
-
-def test_command_idedata_incompatible_toolchain(tmp_path: Path) -> None:
-    """A non-native, non-platformio toolchain errors out cleanly."""
-    setup_core(platform=PLATFORM_ESP32, tmp_path=tmp_path)
-    CORE.toolchain = Toolchain.SDK_NRF
-
-    assert command_idedata(MagicMock(), CORE.config) == 1
-
-
@pytest.mark.parametrize(
    "error",
    [
@@ -7592,46 +7396,6 @@ def test_compile_program_espidf_idedata_none_warns(
    assert "No idedata was generated" in caplog.text


-def test_native_toolchain_table_serves_every_native_toolchain() -> None:
-    """Every member of NATIVE_TOOLCHAINS has a backend entry; a gap would
-    surface as a targeted EsphomeError on the one affected config, and this
-    pin keeps the table from drifting when a toolchain is added."""
-    from esphome.const import NATIVE_TOOLCHAINS
-
-    assert {tc for _, tc in main._NATIVE_TOOLCHAIN_MODULES} == set(NATIVE_TOOLCHAINS)
-
-
-def test_native_toolchain_module_missing_backend_raises(tmp_path: Path) -> None:
-    """A native toolchain missing from the backend table is a bug and must
-    fail, not silently degrade to the PlatformIO path."""
-    setup_core(platform=PLATFORM_ESP8266, tmp_path=tmp_path, name="test_device")
-    CORE.toolchain = Toolchain.ARDUINO
-    with (
-        patch.dict(main._NATIVE_TOOLCHAIN_MODULES, clear=True),
-        pytest.raises(EsphomeError, match="no native build backend"),
-    ):
-        _native_toolchain_module()
-
-
-def test_command_analyze_memory_unsupported_toolchain(
-    tmp_path: Path,
-    mock_write_cpp: Mock,
-    mock_compile_program: Mock,
-    caplog: pytest.LogCaptureFixture,
-) -> None:
-    """A hook-less non-PlatformIO toolchain is refused by name, never routed
-    into the PlatformIO branch."""
-    setup_core(platform=PLATFORM_NRF52, tmp_path=tmp_path, name="test_device")
-    CORE.toolchain = Toolchain.SDK_NRF
-    mock_write_cpp.return_value = 0
-    mock_compile_program.return_value = 0
-
-    result = command_analyze_memory(MockArgs(), {CONF_ESPHOME: {CONF_NAME: "t"}})
-
-    assert result == 1
-    assert "analyze-memory is not supported" in caplog.text
-
-
 def test_cli_toolchain_skips_the_validated_config_cache(tmp_path: Path) -> None:
    """An explicit --toolchain must run the per-platform validators, so the
    upload/logs fast path becomes a cache miss."""
@@ -7647,29 +7411,6 @@ def test_cli_toolchain_skips_the_validated_config_cache(tmp_path: Path) -> None:
    mock_read.assert_called_once()


-def test_upload_using_esptool_native_missing_firmware_raises(
-    tmp_path: Path,
-) -> None:
-    """A stale or absent firmware.bin fails by name instead of flashing air."""
-    setup_core(platform=PLATFORM_ESP8266, tmp_path=tmp_path, name="test")
-    CORE.toolchain = Toolchain.ARDUINO
-    with pytest.raises(EsphomeError, match="compile the configuration first"):
-        upload_using_esptool(
-            {CONF_ESPHOME: {"platformio_options": {}}}, "/dev/ttyUSB0", None, None
-        )
-
-
-def test_compile_program_unclaimed_native_toolchain_raises(
-    tmp_path: Path,
-) -> None:
-    """A resolved native toolchain no platform backend claims must fail,
-    never fall through to the PlatformIO project path."""
-    setup_core(platform=PLATFORM_ESP32, tmp_path=tmp_path, name="test_device")
-    CORE.toolchain = Toolchain.ARDUINO  # esp32 has no arduino-native backend
-    with pytest.raises(EsphomeError, match="no platform backend claimed"):
-        compile_program(MockArgs(), {})
-
-
 def test_cli_toolchain_still_refreshes_the_validated_config_cache(
    tmp_path: Path,
 ) -> None:
@@ -516,13 +516,10 @@ def test_clean_build(
    dependencies_lock = tmp_path / "dependencies.lock"
    dependencies_lock.write_text("lock file")

-    # idedata caches live under the data dir, not the build path; the
-    # .arduino.json variant is the native esp8266 toolchain's.
+    # idedata cache lives under the data dir, not the build path.
    idedata_cache = tmp_path / "idedata" / "test.json"
    idedata_cache.parent.mkdir()
    idedata_cache.write_text("{}")
-    arduino_idedata_cache = tmp_path / "idedata" / "test.arduino.json"
-    arduino_idedata_cache.write_text("{}")

    # Native ESP-IDF toolchain artifacts.
    idf_build_dir = tmp_path / "build"
@@ -583,7 +580,6 @@ def test_clean_build(
    assert not piolibdeps_dir.exists()
    assert not dependencies_lock.exists()
    assert not idedata_cache.exists()
-    assert not arduino_idedata_cache.exists()
    assert not idf_build_dir.exists()
    assert not managed_components_dir.exists()
    assert not pio_components_dir.exists()
Author	SHA1	Message	Date
J. Nick Koston	b984f63c49	Merge remote-tracking branch 'origin/dev' into api-reverse-connection # Conflicts: # tests/integration/test_light_initial_state.py	2026-09-08 18:13:24 +02:00
J. Nick Koston	78f055299c	Merge remote-tracking branch 'origin/dev' into api-reverse-connection # Conflicts: # tests/integration/test_api_zero_psk_provisioning.py	2026-09-08 18:11:39 +02:00
J. Nick Koston	1ce0bed3f6	[core] Share compiled binaries across modbus integration tests (#18945 )	2026-09-08 18:10:45 +02:00
J. Nick Koston	7f9812cef6	Terminate the loaded target before logging it, validate udp addresses on the raw lwip branch too, and resolve the socket default in the lwip_tcp test	2026-09-05 13:07:37 +02:00
J. Nick Koston	a684e7e67d	Decide the listener failure policy in setup, enforce the slot limit once, and reject lwip_tcp through the resolved socket implementation only	2026-09-05 11:23:59 +02:00
J. Nick Koston	afc93a4dc8	Warn when any UDP address is dropped and print the boot delay with PRIu32	2026-09-04 21:21:50 +02:00
J. Nick Koston	0a74cb4e89	Apply the dial delay the same way at boot and after a disconnect, tell socket create and setblocking failures apart, and cap the delay so the wait always elapses	2026-09-04 12:42:07 +02:00
J. Nick Koston	9c4a08aaad	Capture errno before it can be clobbered, warn when no UDP address is valid, and give the reboot test timing headroom	2026-09-04 07:25:50 +02:00
J. Nick Koston	68d5968405	Skip the dial delay when no inbound path waits, keep dial-out alive when the listener fails, check the socket results this PR made meaningful, and cover the clean reboot branch	2026-09-04 06:14:00 +02:00
J. Nick Koston	30da0e81fa	Adopt the shared connect poll in async_tcp and name the refused implementation	2026-09-03 18:54:23 +02:00
J. Nick Koston	900638463a	Move the connect poll into the socket component and dedupe target persistence	2026-09-03 17:41:48 +02:00
J. Nick Koston	1665d509d4	Bound the delay against uint32 wrap and print the effective boot delay	2026-09-03 12:16:42 +02:00
J. Nick Koston	29d8f9c7c6	Name the reboot cause and log the loaded target at setup	2026-09-03 11:28:32 +02:00
J. Nick Koston	18b5277254	Accept a bare outgoing_connection block and log the bound enforcement	2026-09-02 12:26:19 +02:00
J. Nick Koston	b110cee973	Keep the platform level error message alongside the socket implementation check	2026-09-02 12:18:32 +02:00
J. Nick Koston	1171fbf892	Extract a reusable connect poll helper and enforce bounds at the write	2026-09-02 11:58:51 +02:00
J. Nick Koston	ae549b25bb	Report address parse failures from set_sockaddr and drop duplicated policy	2026-09-02 11:36:57 +02:00
J. Nick Koston	35ab455c10	Use the portable INADDR_NONE, self heal a bad remembered target, retry failed saves	2026-09-02 11:18:37 +02:00
J. Nick Koston	dae9a5d1a6	Harden dial target validation and keep a fresh address on flash failure	2026-08-31 21:31:06 -04:00
J. Nick Koston	bf380037a6	Refresh the watchdog on every authenticated removal	2026-08-31 21:01:03 -04:00
J. Nick Koston	493c7265ab	Fix the IPv6 target guard so it actually compiles in	2026-08-31 20:44:29 -04:00
J. Nick Koston	238b6bb0b7	Simplify dial bookkeeping and settle the watchdog policy	2026-08-31 20:20:50 -04:00
J. Nick Koston	0211bdf2c0	Address review round: backoff fairness, watchdog integrity, silent failures	2026-08-31 19:26:01 -04:00
J. Nick Koston	a95bfe0bcb	Tighten comments and member ordering	2026-08-31 18:42:28 -04:00
J. Nick Koston	3a0bbc4c17	Merge remote-tracking branch 'origin/dev' into api-reverse-connection	2026-08-31 18:40:27 -04:00
J. Nick Koston	cc9dc95cab	Only dial immediately at boot for deep sleep devices	2026-08-31 18:24:40 -04:00
J. Nick Koston	79325fe59a	Dial immediately when no client has ever connected and polish review nits	2026-08-31 17:36:57 -04:00
pre-commit-ci-lite[bot]	5fbe09b68c	apply automatic formatting fixes	2026-08-31 21:28:10 +00:00
J. Nick Koston	f41ff5aaeb	Merge remote-tracking branch 'origin/dev' into api-reverse-connection	2026-08-31 17:26:02 -04:00
J. Nick Koston	7b57fdd35c	Gate the dial-back flag on this connection's transport and tune redial policy	2026-08-31 17:19:17 -04:00
J. Nick Koston	fc671d38e5	Address review findings and advertise support in device info	2026-08-31 16:44:49 -04:00
J. Nick Koston	4e0cda0287	Select the dial-back target with an explicit hello flag instead of guessing from client info	2026-08-31 15:40:15 -04:00
J. Nick Koston	676eac7686	[api] Add outgoing connections so the device can dial Home Assistant	2026-08-31 14:06:05 -05:00