diff --git a/esphome/components/feedback/feedback_cover.cpp b/esphome/components/feedback/feedback_cover.cpp
index 672e99949b..1139e6fa18 100644
--- a/esphome/components/feedback/feedback_cover.cpp
+++ b/esphome/components/feedback/feedback_cover.cpp
@@ -375,12 +375,10 @@ void FeedbackCover::start_direction_(CoverOperation dir) {
   // check if we have a wait time
   if (this->direction_change_waittime_.has_value() && dir != COVER_OPERATION_IDLE &&
       this->current_operation != COVER_OPERATION_IDLE && dir != this->current_operation) {
+    const uint32_t waittime = *this->direction_change_waittime_;
     ESP_LOGD(TAG, "'%s' - Reversing direction.", this->name_.c_str());
     this->start_direction_(COVER_OPERATION_IDLE);
-
-    this->set_timeout(DIRECTION_CHANGE_TIMEOUT_ID, *this->direction_change_waittime_,
-                      [this, dir]() { this->start_direction_(dir); });
-
+    this->set_timeout(DIRECTION_CHANGE_TIMEOUT_ID, waittime, [this, dir]() { this->start_direction_(dir); });
   } else {
     this->set_current_operation_(dir, true);
     this->prev_command_trigger_ = trig;
diff --git a/esphome/external_files.py b/esphome/external_files.py
index 8efebd047d..dfabc54f47 100644
--- a/esphome/external_files.py
+++ b/esphome/external_files.py
@@ -211,10 +211,11 @@ def download_content_many(
     """Run `download_content` for each (url, path) pair concurrently.
 
     Wall time drops from `sum(latency)` to roughly `max(latency)` for cached
-    files where the HEAD round-trip dominates. Worker exceptions propagate
-    when iteration reaches the corresponding input item (`ex.map` yields
-    results in input order), and remaining workers complete before this
-    returns.
+    files where the HEAD round-trip dominates. All workers run to
+    completion before this returns; every `cv.Invalid` raised by a worker
+    is collected and surfaced together as `cv.MultipleInvalid` so the user
+    sees every broken file in a single validation pass instead of fixing
+    them one round-trip at a time.
 
     Items are de-duplicated by `path` -- two callers asking for the same
     cache file (e.g. the same URL referenced twice in a config) would
@@ -238,9 +239,19 @@ def download_content_many(
         download_content(url, path, timeout)
 
     workers = max(1, min(max_workers, len(seen)))
+    errors: list[cv.Invalid] = []
     with ThreadPoolExecutor(max_workers=workers) as ex:
-        # list() forces iteration so exceptions surface here, not silently.
-        list(ex.map(_download_one, seen.items()))
+        futures = [ex.submit(_download_one, item) for item in seen.items()]
+        for future in futures:
+            try:
+                future.result()
+            except cv.Invalid as e:
+                errors.append(e)
+    if not errors:
+        return
+    if len(errors) == 1:
+        raise errors[0]
+    raise cv.MultipleInvalid(errors)
 
 
 # Each component that uses external_files defines its own local
diff --git a/script/build_helpers.py b/script/build_helpers.py
index 4cf2f93fbb..0e0e8170a0 100644
--- a/script/build_helpers.py
+++ b/script/build_helpers.py
@@ -57,6 +57,59 @@ def hash_components(components: list[str]) -> str:
     return hashlib.sha256(key.encode()).hexdigest()[:16]
 
 
+def populate_dependency_config(
+    config: dict,
+    component_names: list[str],
+    *,
+    get_component_fn: Callable[[str], object | None] = get_component,
+    register_platform_fn: Callable[[str], None] | None = None,
+) -> None:
+    """Populate ``config`` with empty entries for transitive dependencies.
+
+    For every name in ``component_names``:
+
+    * ``domain.platform`` form (e.g. ``sensor.gpio``) appends
+      ``{platform: <name>}`` to ``config[domain]``, creating the list if needed.
+    * Bare components are looked up via ``get_component_fn``. Platform
+      components (``IS_PLATFORM_COMPONENT``) and ``MULTI_CONF`` components are
+      initialised as ``[]`` so the sibling ``domain.platform`` branch can
+      ``append`` into them. Everything else is populated by running the
+      component's schema with ``{}`` so defaults exist; if the schema requires
+      explicit input, an empty ``{}`` is used as a fallback.
+
+    Platform components must always be a list here even when no
+    ``domain.platform`` entry follows, because the ``domain.platform`` branch
+    does ``config.setdefault(domain, []).append(...)`` and would crash on a
+    leftover dict.
+    """
+    if register_platform_fn is None:
+        register_platform_fn = CORE.testing_ensure_platform_registered
+    for component_name in component_names:
+        if "." in component_name:
+            domain, component = component_name.split(".", maxsplit=1)
+            domain_list = config.setdefault(domain, [])
+            register_platform_fn(domain)
+            domain_list.append({CONF_PLATFORM: component})
+            continue
+        # Skip "core" — it's a pseudo-component handled by the build
+        # system, not a real loadable component (get_component returns None)
+        component = get_component_fn(component_name)
+        if component is None:
+            continue
+        if component.multi_conf or component.is_platform_component:
+            config.setdefault(component_name, [])
+        elif component_name not in config:
+            schema = component.config_schema
+            try:
+                config[component_name] = schema({}) if schema is not None else {}
+            except Exception:  # noqa: BLE001
+                # Schema requires explicit input we can't synthesize; fall
+                # back to an empty mapping so subscripting at least returns
+                # KeyError on missing keys rather than crashing on the
+                # wrong type.
+                config[component_name] = {}
+
+
 def filter_components_with_files(components: list[str], tests_dir: Path) -> list[str]:
     """Filter out components that do not have .cpp or .h files in the tests dir.
 
@@ -316,31 +369,7 @@ def compile_and_get_binary(
 
     # Add remaining components and dependencies to the configuration after
     # validation, so their source files are included in the build.
-    for component_name in components_with_dependencies:
-        if "." in component_name:
-            domain, component = component_name.split(".", maxsplit=1)
-            domain_list = config.setdefault(domain, [])
-            CORE.testing_ensure_platform_registered(domain)
-            domain_list.append({CONF_PLATFORM: component})
-        # Skip "core" — it's a pseudo-component handled by the build
-        # system, not a real loadable component (get_component returns None)
-        elif (component := get_component(component_name)) is not None:
-            # MULTI_CONF components store their config as a list of dicts,
-            # everything else stores a single dict. Run the component's
-            # schema with {} so defaults get populated -- code paths like
-            # socket.FILTER_SOURCE_FILES expect a fully-populated mapping.
-            if component.multi_conf:
-                config.setdefault(component_name, [])
-            elif component_name not in config:
-                schema = component.config_schema
-                try:
-                    config[component_name] = schema({}) if schema is not None else {}
-                except Exception:  # noqa: BLE001
-                    # Schema requires explicit input we can't synthesize; fall
-                    # back to an empty mapping so subscripting at least returns
-                    # KeyError on missing keys rather than crashing on the
-                    # wrong type.
-                    config[component_name] = {}
+    populate_dependency_config(config, components_with_dependencies)
 
     # Register platforms from the extra config (benchmark.yaml) so
     # USE_SENSOR, USE_LIGHT, etc. defines are emitted without needing
diff --git a/tests/script/test_test_helpers.py b/tests/script/test_test_helpers.py
index 467940fc33..3149712563 100644
--- a/tests/script/test_test_helpers.py
+++ b/tests/script/test_test_helpers.py
@@ -258,3 +258,161 @@ def test_load_wraps_platform_component(tmp_path: Path) -> None:
     assert key == "bthome.sensor"
     assert isinstance(installed, ComponentManifestOverride)
     assert installed.to_code is None
+
+
+# ---------------------------------------------------------------------------
+# populate_dependency_config
+# ---------------------------------------------------------------------------
+
+
+def _make_component_stub(
+    *,
+    multi_conf: bool = False,
+    is_platform_component: bool = False,
+    config_schema=None,
+) -> MagicMock:
+    stub = MagicMock()
+    stub.multi_conf = multi_conf
+    stub.is_platform_component = is_platform_component
+    stub.config_schema = config_schema
+    return stub
+
+
+def test_populate_platform_component_listed_alone_uses_list() -> None:
+    """Regression: a platform component (sensor) with no `sensor.x` siblings
+    must land as `[]` in config. Previously it was populated as a dict via
+    `schema({})`, which then crashed the sibling `domain.platform` branch
+    when later dependencies tried `config.setdefault('sensor', []).append(...)`.
+    """
+    sensor = _make_component_stub(is_platform_component=True)
+    config: dict = {}
+
+    build_helpers.populate_dependency_config(
+        config,
+        ["sensor"],
+        get_component_fn=lambda name: sensor if name == "sensor" else None,
+        register_platform_fn=lambda _: None,
+    )
+
+    assert config["sensor"] == []
+
+
+def test_populate_platform_component_then_platform_entry() -> None:
+    """When `sensor` is processed before `sensor.gpio` (sorted order),
+    the bare-component branch must leave `config['sensor']` as a list so
+    the platform-entry branch can append into it.
+    """
+    sensor = _make_component_stub(is_platform_component=True)
+    gpio = _make_component_stub()  # the bare `gpio` component
+    components: dict[str, object] = {"sensor": sensor, "gpio": gpio}
+    config: dict = {}
+
+    build_helpers.populate_dependency_config(
+        config,
+        ["gpio", "sensor", "sensor.gpio"],
+        get_component_fn=components.get,
+        register_platform_fn=lambda _: None,
+    )
+
+    assert config["sensor"] == [{"platform": "gpio"}]
+
+
+def test_populate_multi_conf_component_uses_list() -> None:
+    multi = _make_component_stub(multi_conf=True)
+    config: dict = {}
+
+    build_helpers.populate_dependency_config(
+        config,
+        ["multi"],
+        get_component_fn=lambda name: multi if name == "multi" else None,
+        register_platform_fn=lambda _: None,
+    )
+
+    assert config["multi"] == []
+
+
+def test_populate_plain_component_uses_schema_defaults() -> None:
+    schema = MagicMock(return_value={"default_key": 42})
+    plain = _make_component_stub(config_schema=schema)
+    config: dict = {}
+
+    build_helpers.populate_dependency_config(
+        config,
+        ["plain"],
+        get_component_fn=lambda name: plain if name == "plain" else None,
+        register_platform_fn=lambda _: None,
+    )
+
+    schema.assert_called_once_with({})
+    assert config["plain"] == {"default_key": 42}
+
+
+def test_populate_plain_component_falls_back_when_schema_raises() -> None:
+    def picky_schema(_):
+        raise ValueError("required field missing")
+
+    plain = _make_component_stub(config_schema=picky_schema)
+    config: dict = {}
+
+    build_helpers.populate_dependency_config(
+        config,
+        ["plain"],
+        get_component_fn=lambda name: plain if name == "plain" else None,
+        register_platform_fn=lambda _: None,
+    )
+
+    assert config["plain"] == {}
+
+
+def test_populate_skips_unresolvable_pseudo_components() -> None:
+    """`core` and other names that get_component returns None for are skipped
+    silently without inserting anything into the config.
+    """
+    config: dict = {}
+
+    build_helpers.populate_dependency_config(
+        config,
+        ["core"],
+        get_component_fn=lambda _: None,
+        register_platform_fn=lambda _: None,
+    )
+
+    assert config == {}
+
+
+def test_populate_preserves_existing_plain_component_config() -> None:
+    """If a plain component already has a config entry (e.g. from the user's
+    YAML), the schema-defaults branch must not overwrite it.
+    """
+    schema = MagicMock()
+    plain = _make_component_stub(config_schema=schema)
+    config: dict = {"plain": {"user_key": "set_by_user"}}
+
+    build_helpers.populate_dependency_config(
+        config,
+        ["plain"],
+        get_component_fn=lambda name: plain if name == "plain" else None,
+        register_platform_fn=lambda _: None,
+    )
+
+    schema.assert_not_called()
+    assert config["plain"] == {"user_key": "set_by_user"}
+
+
+def test_populate_registers_platform_for_platform_entry() -> None:
+    """Each `domain.platform` entry triggers register_platform_fn(domain) so
+    USE_<DOMAIN> defines get emitted later in the build pipeline.
+    """
+    registered: list[str] = []
+    config: dict = {}
+
+    build_helpers.populate_dependency_config(
+        config,
+        ["sensor.gpio", "binary_sensor.gpio"],
+        get_component_fn=lambda _: None,
+        register_platform_fn=registered.append,
+    )
+
+    assert registered == ["sensor", "binary_sensor"]
+    assert config["sensor"] == [{"platform": "gpio"}]
+    assert config["binary_sensor"] == [{"platform": "gpio"}]
diff --git a/tests/unit_tests/test_external_files.py b/tests/unit_tests/test_external_files.py
index b816e986e0..0b545f9ed8 100644
--- a/tests/unit_tests/test_external_files.py
+++ b/tests/unit_tests/test_external_files.py
@@ -9,7 +9,7 @@ import pytest
 import requests
 
 from esphome import external_files
-from esphome.config_validation import Invalid
+from esphome.config_validation import Invalid, MultipleInvalid
 from esphome.core import CORE, EsphomeError, TimePeriod
 
 
@@ -574,65 +574,6 @@ def test_download_content_skip_external_update_downloads_when_missing(
     assert test_file.read_bytes() == new_content
 
 
-def test_download_content_saves_etag(
-    mock_has_remote_file_changed: MagicMock,
-    mock_requests_get: MagicMock,
-    setup_core: Path,
-) -> None:
-    """Test download_content writes the ETag sidecar after a successful download."""
-    test_file = setup_core / "fresh.txt"
-    new_content = b"fresh content"
-
-    mock_has_remote_file_changed.return_value = True
-    mock_response = MagicMock()
-    mock_response.content = new_content
-    mock_response.headers = {external_files.ETAG: '"deadbeef"'}
-    mock_response.raise_for_status = MagicMock()
-    mock_requests_get.return_value = mock_response
-
-    url = "https://example.com/file.txt"
-    external_files.download_content(url, test_file)
-
-    assert external_files._etag_sidecar_path(test_file).read_text() == '"deadbeef"'
-
-
-def test_download_content_atomic_write_no_partial_on_failure(
-    mock_has_remote_file_changed: MagicMock,
-    mock_requests_get: MagicMock,
-    mock_write_file: MagicMock,
-    setup_core: Path,
-) -> None:
-    """If `write_file` (the atomic-write helper) fails, the existing cache
-    file must remain untouched and no temp files may be left behind. Patching
-    `write_file` directly exercises the atomic-rename path -- a failure inside
-    `write_file` is the only reason the rename wouldn't have happened.
-    """
-    from esphome.core import EsphomeError
-
-    test_file = setup_core / "cached.txt"
-    original_content = b"original content"
-    test_file.write_bytes(original_content)
-
-    mock_has_remote_file_changed.return_value = True
-    mock_response = MagicMock()
-    mock_response.content = b"new content"
-    mock_response.headers = {}
-    mock_response.raise_for_status = MagicMock()
-    mock_requests_get.return_value = mock_response
-
-    mock_write_file.side_effect = EsphomeError("disk full")
-
-    with pytest.raises(EsphomeError, match="disk full"):
-        external_files.download_content("https://example.com/file.txt", test_file)
-
-    # Original file is untouched -- write_file aborted before its rename step.
-    assert test_file.read_bytes() == original_content
-    # write_file is responsible for cleaning its own temp files; nothing leaks
-    # into the cache directory either way.
-    leftover_tmps = list(setup_core.glob("tmp*"))
-    assert leftover_tmps == []
-
-
 def test_download_content_many_empty_is_noop(
     mock_download_content: MagicMock, setup_core: Path
 ) -> None:
@@ -676,10 +617,12 @@ def test_download_content_many_runs_in_parallel(
     assert mock_download_content.call_count == 3
 
 
-def test_download_content_many_propagates_errors(
+def test_download_content_many_propagates_single_error(
     mock_download_content: MagicMock, setup_core: Path
 ) -> None:
-    """An exception from any worker must propagate out of download_content_many."""
+    """A single failing worker should raise its `Invalid` directly, not wrap
+    it in a `MultipleInvalid` that the caller would have to unpack.
+    """
 
     def fake_download(url: str, path: Path, timeout: int) -> bytes:
         if url.endswith("bad"):
@@ -691,8 +634,37 @@ def test_download_content_many_propagates_errors(
         ("https://example.com/ok", setup_core / "ok"),
         ("https://example.com/bad", setup_core / "bad"),
     ]
-    with pytest.raises(Invalid, match="could not download"):
+    with pytest.raises(Invalid, match="could not download") as exc_info:
         external_files.download_content_many(items)
+    assert not isinstance(exc_info.value, MultipleInvalid)
+
+
+def test_download_content_many_aggregates_multiple_errors(
+    mock_download_content: MagicMock, setup_core: Path
+) -> None:
+    """Every failing worker should be reported in a single MultipleInvalid so
+    the user sees all broken URLs in one validation pass instead of fixing
+    them one network round-trip at a time.
+    """
+
+    def fake_download(url: str, path: Path, timeout: int) -> bytes:
+        if url.endswith("ok"):
+            return b""
+        raise Invalid(f"could not download {url}")
+
+    mock_download_content.side_effect = fake_download
+    items = [
+        ("https://example.com/ok", setup_core / "ok"),
+        ("https://example.com/bad1", setup_core / "bad1"),
+        ("https://example.com/bad2", setup_core / "bad2"),
+    ]
+    with pytest.raises(MultipleInvalid) as exc_info:
+        external_files.download_content_many(items)
+    messages = {str(e) for e in exc_info.value.errors}
+    assert messages == {
+        "could not download https://example.com/bad1",
+        "could not download https://example.com/bad2",
+    }
 
 
 def test_download_content_many_dedupes_by_path(
@@ -767,3 +739,62 @@ def test_download_web_files_in_config_no_web_entries(
     external_files.download_web_files_in_config(config, lambda _: setup_core / "x")
     mock_download_content_many.assert_called_once()
     assert list(mock_download_content_many.call_args[0][0]) == []
+
+
+def test_download_content_saves_etag(
+    mock_has_remote_file_changed: MagicMock,
+    mock_requests_get: MagicMock,
+    setup_core: Path,
+) -> None:
+    """Test download_content writes the ETag sidecar after a successful download."""
+    test_file = setup_core / "fresh.txt"
+    new_content = b"fresh content"
+
+    mock_has_remote_file_changed.return_value = True
+    mock_response = MagicMock()
+    mock_response.content = new_content
+    mock_response.headers = {external_files.ETAG: '"deadbeef"'}
+    mock_response.raise_for_status = MagicMock()
+    mock_requests_get.return_value = mock_response
+
+    url = "https://example.com/file.txt"
+    external_files.download_content(url, test_file)
+
+    assert external_files._etag_sidecar_path(test_file).read_text() == '"deadbeef"'
+
+
+def test_download_content_atomic_write_no_partial_on_failure(
+    mock_has_remote_file_changed: MagicMock,
+    mock_requests_get: MagicMock,
+    mock_write_file: MagicMock,
+    setup_core: Path,
+) -> None:
+    """If `write_file` (the atomic-write helper) fails, the existing cache
+    file must remain untouched and no temp files may be left behind. Patching
+    `write_file` directly exercises the atomic-rename path -- a failure inside
+    `write_file` is the only reason the rename wouldn't have happened.
+    """
+    from esphome.core import EsphomeError
+
+    test_file = setup_core / "cached.txt"
+    original_content = b"original content"
+    test_file.write_bytes(original_content)
+
+    mock_has_remote_file_changed.return_value = True
+    mock_response = MagicMock()
+    mock_response.content = b"new content"
+    mock_response.headers = {}
+    mock_response.raise_for_status = MagicMock()
+    mock_requests_get.return_value = mock_response
+
+    mock_write_file.side_effect = EsphomeError("disk full")
+
+    with pytest.raises(EsphomeError, match="disk full"):
+        external_files.download_content("https://example.com/file.txt", test_file)
+
+    # Original file is untouched -- write_file aborted before its rename step.
+    assert test_file.read_bytes() == original_content
+    # write_file is responsible for cleaning its own temp files; nothing leaks
+    # into the cache directory either way.
+    leftover_tmps = list(setup_core.glob("tmp*"))
+    assert leftover_tmps == []