diff --git a/esphome/arduino8266/build_tool.py b/esphome/arduino8266/build_tool.py
new file mode 100644
index 0000000000..bfcf4128eb
--- /dev/null
+++ b/esphome/arduino8266/build_tool.py
@@ -0,0 +1,36 @@
+"""Tiny cross-platform build steps invoked from the generated ninja file.
+
+Plain script (not ``python -m``): it runs from ninja with whatever Python
+started esphome and must not depend on the package being importable.
+
+Subcommands:
+    ar <ar-binary> <archive> <rspfile>   remove stale archive, then ``ar rc``
+    copy <src> <dst>                     copy a file
+"""
+
+from pathlib import Path
+import shutil
+import subprocess
+import sys
+
+
+def main() -> int:
+    mode = sys.argv[1]
+    if mode == "ar":
+        ar, archive, rspfile = sys.argv[2:5]
+        # Remove first: ``ar rc`` replaces members but never drops ones whose
+        # source was removed from the build, which would leak stale objects.
+        Path(archive).unlink(missing_ok=True)
+        return subprocess.run(
+            [ar, "rc", archive, f"@{rspfile}"], check=False
+        ).returncode
+    if mode == "copy":
+        src, dst = sys.argv[2:4]
+        shutil.copyfile(src, dst)
+        return 0
+    print(f"unknown build_tool mode: {mode}", file=sys.stderr)
+    return 1
+
+
+if __name__ == "__main__":  # pragma: no cover
+    sys.exit(main())
diff --git a/esphome/arduino8266/component.py b/esphome/arduino8266/component.py
new file mode 100644
index 0000000000..17fd5471b4
--- /dev/null
+++ b/esphome/arduino8266/component.py
@@ -0,0 +1,232 @@
+"""Arduino ESP8266 backend for the shared PlatformIO library converter.
+
+Turns the libraries registered via ``cg.add_library()`` into build inputs for
+the ninja generator. Bare names that exist under the framework's bundled
+``libraries/`` directory (ESP8266WiFi, Wire, SPI, ...) are read straight from
+the framework tree; everything else goes through the shared
+resolution/download pipeline in ``esphome.platformio.library``.
+
+Mirrors PlatformIO's ``lib_ldf_mode=off`` behavior: each library builds into
+its own static archive and every library's include dir joins one global
+include path.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+import logging
+from pathlib import Path
+
+from esphome.build_helpers.extra_script import apply_extra_script
+from esphome.core import CORE, EsphomeError, Library
+from esphome.platformio.library import (
+    DEFAULT_BUILD_INCLUDE_DIR,
+    DEFAULT_BUILD_SRC_FILTER,
+    SRC_FILE_EXTENSIONS,
+    ConvertedLibrary,
+    InvalidLibrary,
+    LibraryBackend,
+    check_library_data,
+    collect_filtered_files,
+    convert_libraries,
+    ensure_list,
+    is_lib_ignored,
+    join_flag_args,
+    lib_ignore_set,
+    normalize_dependencies,
+    parse_library_properties,
+    split_flag_entry,
+)
+
+_LOGGER = logging.getLogger(__name__)
+
+ESP8266_PLATFORM = "espressif8266"
+
+
+@dataclass
+class ArduinoLibrary:
+    """One resolved library, ready for the ninja generator."""
+
+    name: str
+    sources: list[Path] = field(default_factory=list)
+    include_dirs: list[Path] = field(default_factory=list)
+    # Extra compile flags private to this library's own sources
+    flags: list[str] = field(default_factory=list)
+    # Link inputs the library contributes (-L dirs / -l libs, e.g. from
+    # precompiled vendor blobs) and -Wl, options for the firmware link
+    link_dirs: list[Path] = field(default_factory=list)
+    link_libs: list[str] = field(default_factory=list)
+    link_flags: list[str] = field(default_factory=list)
+
+
+def _library_info(name: str, read_path: Path, data: dict) -> ArduinoLibrary:
+    """Resolve one library's sources, include dirs, and flags (PIO semantics)."""
+    build = data.get("build", {})
+
+    # PIO's source-dir resolution: manifest srcDir, else src/Src, else the root
+    src_dir = build.get("srcDir") or next(
+        (d for d in ("src", "Src") if (read_path / d).is_dir()), "."
+    )
+    if "srcDir" in build and not (read_path / src_dir).is_dir():
+        # Unlike the default probes, an explicitly declared srcDir that does
+        # not resolve is unambiguously a manifest/tree error; a silently
+        # empty source set would surface as link errors far from the cause
+        raise EsphomeError(
+            f"Library {name} declares srcDir {src_dir} which does not exist"
+        )
+
+    src_filter = ensure_list(build.get("srcFilter", DEFAULT_BUILD_SRC_FILTER))
+    # PlatformIO shell-lexes each build.flags entry
+    flag_tokens = join_flag_args(
+        (
+            token
+            for entry in ensure_list(build.get("flags", []))
+            for token in split_flag_entry(entry, f"library {name}")
+        ),
+        f"library {name}",
+    )
+
+    lib = ArduinoLibrary(name=name)
+    include_flags: list[str] = []
+    for tok in flag_tokens:
+        if tok.startswith("-I"):
+            include_flags.append(tok[2:])
+        elif tok.startswith("-L"):
+            link_dir = (read_path / tok[2:]).resolve()
+            if not link_dir.is_dir():
+                # Kept anyway (the linker ignores missing -L dirs); the
+                # warning names the culprit before a bare "cannot find -lfoo"
+                _LOGGER.warning(
+                    "Library %s declares library dir %s which does not exist",
+                    name,
+                    tok[2:],
+                )
+            lib.link_dirs.append(link_dir)
+        elif tok.startswith("-l"):
+            lib.link_libs.append(tok[2:])
+        elif tok.startswith("-Wl,"):
+            lib.link_flags.append(tok)
+        else:
+            lib.flags.append(tok)
+
+    include_dir = build.get("includeDir", DEFAULT_BUILD_INCLUDE_DIR)
+    for d in [include_dir, src_dir, *include_flags]:
+        if (path := (read_path / d)).is_dir():
+            lib.include_dirs.append(path.resolve())
+        elif d in include_flags or (d == include_dir and "includeDir" in build):
+            # The includeDir/srcDir defaults are probes; an explicitly
+            # declared path that does not resolve is a manifest error
+            _LOGGER.warning(
+                "Library %s declares include dir %s which does not exist", name, d
+            )
+
+    lib.sources = sorted(
+        path.resolve()
+        for f in collect_filtered_files(read_path / src_dir, src_filter)
+        if (path := Path(f)).suffix in SRC_FILE_EXTENSIONS
+    )
+    if not lib.sources and ("srcFilter" in build or "srcDir" in build):
+        # A default probe finding nothing is a header-only library; a
+        # declared filter matching nothing is a manifest/tree problem.
+        _LOGGER.warning(
+            "Library %s declares srcFilter/srcDir but no source files matched",
+            name,
+        )
+    return lib
+
+
+def _bundled_library(framework_path: Path, name: str) -> ArduinoLibrary:
+    """A library bundled with the Arduino core, read from the framework tree."""
+    lib_dir = framework_path / "libraries" / name
+    manifest = lib_dir / "library.properties"
+    data = parse_library_properties(manifest) if manifest.is_file() else {}
+    return _library_info(name, lib_dir, {"name": name, **data})
+
+
+def resolve_libraries(framework_path: Path) -> list[ArduinoLibrary]:
+    """Resolve every ``cg.add_library()`` entry into an :class:`ArduinoLibrary`."""
+    bundled: list[ArduinoLibrary] = []
+    external: list[Library] = []
+    # PlatformIO's lib_ignore covers framework-bundled libraries too; the
+    # shared converter only filters the registry/git ones.
+    lib_ignore = lib_ignore_set()
+    for library in CORE.platformio_libraries.values():
+        if is_lib_ignored(library.name, lib_ignore):
+            continue
+        # A version pin means a registry package ("pngle@1.1.0"), never a
+        # framework-bundled library.
+        if (
+            library.repository
+            or library.version
+            or not library.name
+            or "/" in library.name
+        ):
+            external.append(library)
+        elif (framework_path / "libraries" / library.name).is_dir():
+            bundled.append(_bundled_library(framework_path, library.name))
+        else:
+            # A bare registry name; resolved at the latest version, matching
+            # PlatformIO (a typo fails loudly as a registry lookup error).
+            external.append(library)
+
+    converted: list[ArduinoLibrary] = []
+    bundled_names = {lib.name for lib in bundled}
+
+    def _add_bundled_dependencies(component: ConvertedLibrary) -> None:
+        # A version-less bare-name dependency ("Hash" in ESPAsyncWebServer)
+        # is a core-bundled library; the shared converter skips it because
+        # it cannot be resolved from the registry.
+        for dep in normalize_dependencies(component.data.get("dependencies")):
+            name = dep.get("name")
+            if (
+                not name
+                or dep.get("owner")
+                or "version" in dep
+                or name in bundled_names
+                or is_lib_ignored(name, lib_ignore)
+            ):
+                continue
+            if not (framework_path / "libraries" / name).is_dir():
+                # The shared converter skips version-less deps too, so this
+                # is the only place the drop can be made visible before the
+                # missing sources surface as link errors.
+                _LOGGER.warning(
+                    "Dependency %s of library %s is not bundled with the "
+                    "framework and has no version to resolve; skipping",
+                    name,
+                    component.name,
+                )
+                continue
+            try:
+                check_library_data(dep, ESP8266_PLATFORM, "arduino")
+            except InvalidLibrary as err:
+                # check_library_data's only raise is the platform filter, and
+                # rejecting another platform's dependency of a cross-platform
+                # manifest is routine (every ESPAsyncWebServer build hits it);
+                # a warning here would be noise, and the reason is in the log.
+                _LOGGER.debug("Skipping bundled dependency %s: %s", name, err)
+                continue
+            bundled_names.add(name)
+            bundled.append(_bundled_library(framework_path, name))
+
+    def _emit(component: ConvertedLibrary) -> None:
+        apply_extra_script(component, "esp8266", pio_platform=ESP8266_PLATFORM)
+        converted.append(
+            _library_info(
+                component.get_require_name(), component.source_dir, component.data
+            )
+        )
+        _add_bundled_dependencies(component)
+
+    if external:
+        convert_libraries(
+            external,
+            LibraryBackend(
+                platform=ESP8266_PLATFORM,
+                framework="arduino",
+                emit=_emit,
+                cache_key="arduino8266",
+            ),
+        )
+
+    return bundled + converted
diff --git a/tests/unit_tests/test_arduino8266_build_tool.py b/tests/unit_tests/test_arduino8266_build_tool.py
new file mode 100644
index 0000000000..66d11a6700
--- /dev/null
+++ b/tests/unit_tests/test_arduino8266_build_tool.py
@@ -0,0 +1,63 @@
+"""Tests for the ninja build-tool helper script."""
+
+from __future__ import annotations
+
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from esphome.arduino8266 import build_tool
+
+
+def test_ar_removes_stale_archive(tmp_path: Path) -> None:
+    archive = tmp_path / "lib.a"
+    archive.write_text("stale")
+    rsp = tmp_path / "lib.a.rsp"
+    rsp.write_text("a.o\n")
+    with (
+        patch.object(
+            build_tool.sys,
+            "argv",
+            ["build_tool", "ar", "ar-bin", str(archive), str(rsp)],
+        ),
+        patch.object(
+            build_tool.subprocess, "run", return_value=MagicMock(returncode=0)
+        ) as mock_run,
+    ):
+        assert build_tool.main() == 0
+    assert not archive.exists()
+    assert mock_run.call_args[0][0] == ["ar-bin", "rc", str(archive), f"@{rsp}"]
+
+
+def test_copy(tmp_path: Path) -> None:
+    src = tmp_path / "firmware.bin"
+    src.write_text("data")
+    dst = tmp_path / "firmware.factory.bin"
+    with patch.object(
+        build_tool.sys, "argv", ["build_tool", "copy", str(src), str(dst)]
+    ):
+        assert build_tool.main() == 0
+    assert dst.read_text() == "data"
+
+
+def test_unknown_mode(capsys: pytest.CaptureFixture[str]) -> None:
+    with patch.object(build_tool.sys, "argv", ["build_tool", "bogus"]):
+        assert build_tool.main() == 1
+    assert "unknown build_tool mode" in capsys.readouterr().err
+
+
+def test_runs_as_script(tmp_path: Path) -> None:
+    """The ninja rules invoke the file as a plain script."""
+    import subprocess
+    import sys
+
+    src = tmp_path / "a.bin"
+    src.write_text("x")
+    dst = tmp_path / "b.bin"
+    result = subprocess.run(
+        [sys.executable, build_tool.__file__, "copy", str(src), str(dst)],
+        check=False,
+    )
+    assert result.returncode == 0
+    assert dst.read_text() == "x"
diff --git a/tests/unit_tests/test_arduino8266_component.py b/tests/unit_tests/test_arduino8266_component.py
new file mode 100644
index 0000000000..efe38a68dc
--- /dev/null
+++ b/tests/unit_tests/test_arduino8266_component.py
@@ -0,0 +1,310 @@
+"""Tests for esphome.arduino8266.component (library resolution)."""
+
+from __future__ import annotations
+
+from pathlib import Path
+from unittest.mock import patch
+
+import pytest
+
+from esphome.arduino8266 import component
+from esphome.const import KEY_CORE, KEY_TARGET_PLATFORM, PLATFORM_ESP8266
+from esphome.core import CORE, EsphomeError, Library
+from esphome.platformio.library import ConvertedLibrary, LibraryBackend
+
+
+@pytest.fixture(autouse=True)
+def _reset_libraries() -> None:
+    CORE.platformio_libraries = {}
+    CORE.data[KEY_CORE] = {KEY_TARGET_PLATFORM: PLATFORM_ESP8266}
+
+
+def _add_library(name: str, version: str | None, repository: str | None = None) -> None:
+    CORE.add_library(Library(name=name, version=version, repository=repository))
+
+
+def _make_framework(tmp_path: Path) -> Path:
+    framework = tmp_path / "framework"
+    lib = framework / "libraries" / "ESP8266WiFi" / "src"
+    lib.mkdir(parents=True)
+    (lib / "ESP8266WiFi.cpp").write_text("")
+    (lib / "ESP8266WiFi.h").write_text("")
+    (lib.parent / "library.properties").write_text("name=ESP8266WiFi\nversion=1.0\n")
+    root_lib = framework / "libraries" / "Wire"
+    root_lib.mkdir(parents=True)
+    (root_lib / "Wire.cpp").write_text("")
+    (root_lib / "examples").mkdir()
+    (root_lib / "examples" / "scan.ino").write_text("")
+    return framework
+
+
+def test_library_info_src_layout(tmp_path: Path) -> None:
+    framework = _make_framework(tmp_path)
+    lib = component._bundled_library(framework, "ESP8266WiFi")
+    assert lib.name == "ESP8266WiFi"
+    assert [p.name for p in lib.sources] == ["ESP8266WiFi.cpp"]
+    assert lib.include_dirs == [(framework / "libraries/ESP8266WiFi/src").resolve()]
+
+
+def test_library_info_root_layout_excludes_examples(tmp_path: Path) -> None:
+    framework = _make_framework(tmp_path)
+    lib = component._bundled_library(framework, "Wire")
+    assert [p.name for p in lib.sources] == ["Wire.cpp"]
+    assert lib.include_dirs == [(framework / "libraries/Wire").resolve()]
+
+
+def test_library_info_flags_parsing(tmp_path: Path) -> None:
+    read_path = tmp_path / "lib"
+    (read_path / "src").mkdir(parents=True)
+    (read_path / "src" / "a.cpp").write_text("")
+    (read_path / "inc").mkdir()
+    (read_path / "blobs").mkdir()
+    data = {
+        "build": {
+            "flags": [
+                "-DFOO=1 -I inc",
+                "-lalgobsec",
+                "-fno-lto",
+                "-Wl,--wrap=malloc",
+                "-l",
+                "m",
+                "-L",
+                "blobs",
+            ],
+        }
+    }
+    lib = component._library_info("x", read_path, data)
+    assert lib.flags == ["-DFOO=1", "-fno-lto"]
+    assert lib.include_dirs == [
+        (read_path / "src").resolve(),
+        (read_path / "inc").resolve(),
+    ]
+    assert lib.link_dirs == [(read_path / "blobs").resolve()]
+    assert lib.link_libs == ["algobsec", "m"]
+    assert lib.link_flags == ["-Wl,--wrap=malloc"]
+
+
+def test_library_info_missing_link_dir_warns(
+    tmp_path: Path, caplog: pytest.LogCaptureFixture
+) -> None:
+    read_path = tmp_path / "lib"
+    read_path.mkdir()
+    data = {"build": {"flags": ["-Lmissing_blobs"]}}
+    lib = component._library_info("x", read_path, data)
+    assert "declares library dir missing_blobs which does not exist" in caplog.text
+    # Kept anyway: the linker ignores missing -L dirs
+    assert lib.link_dirs == [(read_path / "missing_blobs").resolve()]
+
+
+def test_library_info_declared_filter_matches_nothing_warns(
+    tmp_path: Path, caplog: pytest.LogCaptureFixture
+) -> None:
+    read_path = tmp_path / "lib"
+    (read_path / "src").mkdir(parents=True)
+    data = {"build": {"srcFilter": ["+<nothing/*>"]}}
+    lib = component._library_info("x", read_path, data)
+    assert not lib.sources
+    assert "declares srcFilter/srcDir but no source files matched" in caplog.text
+
+
+def test_library_info_header_only_does_not_warn(
+    tmp_path: Path, caplog: pytest.LogCaptureFixture
+) -> None:
+    read_path = tmp_path / "lib"
+    (read_path / "src").mkdir(parents=True)
+    lib = component._library_info("x", read_path, {})
+    assert not lib.sources
+    assert "no source files matched" not in caplog.text
+
+
+def test_library_info_no_src_dir(tmp_path: Path) -> None:
+    read_path = tmp_path / "empty"
+    read_path.mkdir()
+    lib = component._library_info("x", read_path, {})
+    # With no manifest hints the source dir falls back to the library root
+    assert lib.sources == []
+    assert lib.include_dirs == [read_path.resolve()]
+
+
+def test_resolve_libraries_bundled(tmp_path: Path) -> None:
+    framework = _make_framework(tmp_path)
+    _add_library("ESP8266WiFi", None)
+    libs = component.resolve_libraries(framework)
+    assert [lib.name for lib in libs] == ["ESP8266WiFi"]
+
+
+def test_resolve_libraries_bare_registry_name_is_external(tmp_path: Path) -> None:
+    """A bare name that is not bundled resolves from the registry at the
+    latest version, matching PlatformIO and the documented libraries: key."""
+    framework = _make_framework(tmp_path)
+    _add_library("pngle", None)
+    with patch.object(component, "convert_libraries", return_value=[]) as mock_convert:
+        component.resolve_libraries(framework)
+    (libraries, _backend), _ = mock_convert.call_args
+    assert [lib.name for lib in libraries] == ["pngle"]
+
+
+def _converted(name: str, source_dir: Path, data: dict) -> ConvertedLibrary:
+    converted = ConvertedLibrary(name, "1.0.0", source=None)
+    converted.path = source_dir
+    converted.data = data
+    return converted
+
+
+def test_resolve_libraries_external_and_bundled_deps(tmp_path: Path) -> None:
+    framework = _make_framework(tmp_path)
+    _add_library("ESP32Async/ESPAsyncWebServer", "3.9.6")
+
+    lib_dir = tmp_path / "converted" / "webserver"
+    (lib_dir / "src").mkdir(parents=True)
+    (lib_dir / "src" / "server.cpp").write_text("")
+    converted = _converted(
+        "esp32async__ESPAsyncWebServer",
+        lib_dir,
+        {
+            "build": {},
+            "dependencies": [
+                # Version-less bundled dependency: resolved from the framework
+                {"name": "Wire", "platforms": "espressif8266"},
+                # Wrong platform: skipped
+                {"name": "ESP8266WiFi", "platforms": "espressif32"},
+                # Registry dependency with a version: handled by the converter
+                {"name": "ESPAsyncTCP", "owner": "ESP32Async", "version": "^2.0.0"},
+                # Not bundled: skipped
+                {"name": "NotBundled"},
+            ],
+        },
+    )
+
+    def fake_convert(libraries: list, backend: LibraryBackend) -> list:
+        assert backend.platform == "espressif8266"
+        assert backend.framework == "arduino"
+        assert backend.cache_key == "arduino8266"
+        backend.emit(converted)
+        return [converted]
+
+    with (
+        patch.object(component, "convert_libraries", side_effect=fake_convert),
+        patch.object(component, "apply_extra_script") as mock_extra,
+    ):
+        libs = component.resolve_libraries(framework)
+
+    mock_extra.assert_called_once_with(
+        converted, "esp8266", pio_platform="espressif8266"
+    )
+    assert [lib.name for lib in libs] == [
+        "Wire",
+        "esp32async__ESPAsyncWebServer",
+    ]
+
+
+def test_resolve_libraries_bundled_dep_already_present(tmp_path: Path) -> None:
+    framework = _make_framework(tmp_path)
+    _add_library("Wire", None)
+    _add_library("Some/External", "1.0.0")
+
+    lib_dir = tmp_path / "converted" / "external"
+    lib_dir.mkdir(parents=True)
+    converted = _converted(
+        "some__External", lib_dir, {"dependencies": [{"name": "Wire"}]}
+    )
+
+    def fake_convert(libraries: list, backend: LibraryBackend) -> list:
+        backend.emit(converted)
+        return [converted]
+
+    with (
+        patch.object(component, "convert_libraries", side_effect=fake_convert),
+        patch.object(component, "apply_extra_script"),
+    ):
+        libs = component.resolve_libraries(framework)
+
+    # Wire appears once (from the explicit registration), not twice
+    assert [lib.name for lib in libs] == ["Wire", "some__External"]
+
+
+def test_resolve_libraries_versioned_bare_name_is_external(tmp_path: Path) -> None:
+    """A bare name with a version pin ("pngle@1.1.0") is a registry package,
+    not a bundled library, and must reach the converter."""
+    framework = _make_framework(tmp_path)
+    _add_library("pngle", "1.1.0")
+
+    with patch.object(component, "convert_libraries", return_value=[]) as mock_convert:
+        component.resolve_libraries(framework)
+
+    (libraries, _backend), _ = mock_convert.call_args
+    assert [lib.name for lib in libraries] == ["pngle"]
+
+
+def test_library_info_trailing_bare_flag_warns(
+    tmp_path: Path, caplog: pytest.LogCaptureFixture
+) -> None:
+    read_path = tmp_path / "lib"
+    (read_path / "src").mkdir(parents=True)
+    lib = component._library_info("x", read_path, {"build": {"flags": ["-DA=1 -l"]}})
+    assert lib.flags == ["-DA=1"]
+    assert lib.link_libs == []
+    assert "Ignoring trailing '-l'" in caplog.text
+
+
+def test_library_info_missing_explicit_include_warns(
+    tmp_path: Path, caplog: pytest.LogCaptureFixture
+) -> None:
+    read_path = tmp_path / "lib"
+    (read_path / "src").mkdir(parents=True)
+    lib = component._library_info("x", read_path, {"build": {"flags": ["-Inope"]}})
+    assert lib.include_dirs == [(read_path / "src").resolve()]
+    assert "include dir nope which does not exist" in caplog.text
+
+
+def test_library_info_missing_declared_src_dir_raises(tmp_path: Path) -> None:
+    """An explicitly declared srcDir that does not exist is a manifest error."""
+    read_path = tmp_path / "lib"
+    read_path.mkdir()
+    with pytest.raises(EsphomeError, match="srcDir nosrc which does not exist"):
+        component._library_info("x", read_path, {"build": {"srcDir": "nosrc"}})
+
+
+def test_library_info_missing_declared_include_dir_warns(
+    tmp_path: Path, caplog: pytest.LogCaptureFixture
+) -> None:
+    read_path = tmp_path / "lib"
+    read_path.mkdir()
+    component._library_info("x", read_path, {"build": {"includeDir": "noinc"}})
+    assert "include dir noinc which does not exist" in caplog.text
+
+
+def test_resolve_libraries_lib_ignore_covers_bundled(tmp_path: Path) -> None:
+    """lib_ignore applies to framework-bundled libraries, as under PlatformIO."""
+    framework = _make_framework(tmp_path)
+    _add_library("ESP8266WiFi", None)
+    _add_library("Wire", None)
+    CORE.platformio_options = {"lib_ignore": ["Wire"]}
+    libs = component.resolve_libraries(framework)
+    assert [lib.name for lib in libs] == ["ESP8266WiFi"]
+
+
+def test_resolve_libraries_lib_ignore_covers_bundled_dependencies(
+    tmp_path: Path,
+) -> None:
+    framework = _make_framework(tmp_path)
+    _add_library("Some/External", "1.0.0")
+    CORE.platformio_options = {"lib_ignore": ["Wire"]}
+
+    lib_dir = tmp_path / "converted" / "external"
+    lib_dir.mkdir(parents=True)
+    converted = _converted(
+        "some__External", lib_dir, {"dependencies": [{"name": "Wire"}]}
+    )
+
+    def fake_convert(libraries: list, backend: LibraryBackend) -> list:
+        backend.emit(converted)
+        return [converted]
+
+    with (
+        patch.object(component, "convert_libraries", side_effect=fake_convert),
+        patch.object(component, "apply_extra_script"),
+    ):
+        libs = component.resolve_libraries(framework)
+
+    assert [lib.name for lib in libs] == ["some__External"]