Close the four diagnostic gaps in the library backend

An owner-qualified dependency name (Owner/Pkg, both halves safe) is the
converter's to resolve and no longer draws the malformed-entry warning,
which stays for genuinely unsafe shapes. A declared srcFilter matching
only inert files now warns like one matching nothing, while matched
headers still read as a header-only library. The short-name suppression
logs the assumed external at debug so an accidental collision is
attributable. A failing ar batch unlinks the truncated archive before
returning its exit code.

esphome/arduino/library.py

@@ -219,9 +219,13 @@ def _collect_lib_sources(
             len(dropped),
             ", ".join(sorted(dropped)),
         )
-    if not lib.sources and not matched 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.
+    if (
+        not lib.sources
+        and ("srcFilter" in build or "srcDir" in build)
+        and not any(Path(f).suffix.lower() in HEADER_FILE_EXTENSIONS for f in matched)
+    ):
+        # A declared filter matching nothing (or only inert files) is a
+        # manifest/tree problem; matched headers mean a header-only library
         _LOGGER.warning(
             "Library %s declares srcFilter/srcDir but no source files matched",
             name,
@@ -361,6 +365,12 @@ def resolve_libraries(
             component.data.get("dependencies"), component.name
         ):
             name = dep.get("name")
+            if isinstance(name, str) and "/" in name:
+                owner, _, pkg = name.partition("/")
+                if _is_safe_library_name(owner) and _is_safe_library_name(pkg):
+                    # PIO's owner-qualified spelling ("Owner/Pkg"); the
+                    # converter resolves it from the registry
+                    continue
             if not _is_safe_library_name(name):
                 # The name becomes a path component under the framework
                 # tree; never join a traversal or a non-string
@@ -370,11 +380,17 @@ def resolve_libraries(
                     component.name,
                 )
                 continue
-            if (
-                name in bundled_names
-                or name in external_short_names
-                or is_lib_ignored(name, lib_ignore)
-            ):
+            if name in external_short_names:
+                # Deliberate when the external really is this library;
+                # attributable when the short-name match is accidental
+                _LOGGER.debug(
+                    "Dependency %s of %s assumed satisfied by a requested "
+                    "external library",
+                    name,
+                    component.name,
+                )
+                continue
+            if name in bundled_names or is_lib_ignored(name, lib_ignore):
                 continue
             if dep.get("owner") or not _provided(name):
                 # Owner-less names in the framework tree prefer the bundled

esphome/build_gen/build_tool.py

@@ -57,6 +57,8 @@ def _run_ar(ar: str, archive: str, rspfile: str) -> int:
             [ar, op, archive, *batch], check=False, close_fds=False
         ).returncode
         if rc != 0:
+            # A failed batch must not leave a truncated archive behind
+            Path(archive).unlink(missing_ok=True)
             return rc
         op = "q"
     return 0

tests/unit_tests/build_gen/test_build_tool.py

@@ -164,8 +164,15 @@ def test_ar_batch_failure_stops(tmp_path: Path) -> None:
             ["build_tool", "ar", "ar-bin", str(archive), str(rsp)],
         ),
         patch.object(
-            build_tool.subprocess, "run", return_value=MagicMock(returncode=3)
+            build_tool.subprocess,
+            "run",
+            side_effect=lambda cmd, **kw: (
+                archive.write_text("partial"),
+                MagicMock(returncode=3),
+            )[1],
         ) as mock_run,
     ):
         assert build_tool.main() == 3
     assert mock_run.call_count == 1
+    # The failed batch must not leave a truncated archive behind
+    assert not archive.exists()

tests/unit_tests/test_arduino_library.py

@@ -490,6 +490,29 @@ def test_library_info_unmapped_sources_warn(
     assert "not compiled: impl.CPP, sketch.ino" in caplog.text
 
 
+def test_library_info_inert_only_filter_warns(
+    tmp_path: Path, caplog: pytest.LogCaptureFixture
+) -> None:
+    """A declared srcFilter matching only inert files (no sources, no
+    headers) warns like one matching nothing at all."""
+    read_path = tmp_path / "lib"
+    (read_path / "src").mkdir(parents=True)
+    (read_path / "src" / "keywords.txt").write_text("")
+    component._library_info("x", read_path, {"build": {"srcFilter": ["+<*>"]}})
+    assert "no source files matched" in caplog.text
+
+
+def test_library_info_declared_filter_matching_headers_stays_quiet(
+    tmp_path: Path, caplog: pytest.LogCaptureFixture
+) -> None:
+    """A declared filter matching real headers is a header-only library."""
+    read_path = tmp_path / "lib"
+    (read_path / "src").mkdir(parents=True)
+    (read_path / "src" / "api.h").write_text("")
+    component._library_info("x", read_path, {"build": {"srcFilter": ["+<*>"]}})
+    assert "no source files matched" not in caplog.text
+
+
 def test_library_info_header_only_src_stays_quiet(
     tmp_path: Path, caplog: pytest.LogCaptureFixture
 ) -> None:
@@ -695,7 +718,6 @@ def test_dict_shorthand_dependency_skips_registry_through_real_converter(
         # A non-string name never leaves the shared normalizer
         (1, "Ignoring unrecognized dependency entry"),
         ("../escape", "Ignoring malformed dependency entry"),
-        ("a/b", "Ignoring malformed dependency entry"),
         ("..", "Ignoring malformed dependency entry"),
     ],
 )
@@ -713,6 +735,24 @@ def test_bundled_dependency_bad_name_is_malformed(
     assert message in caplog.text
 
 
+def test_owner_qualified_dependency_is_silent(
+    tmp_path: Path, caplog: pytest.LogCaptureFixture
+) -> None:
+    """The owner-qualified dependency spelling (PIO's Owner/Pkg) resolves via
+    the converter; it must not draw the malformed-entry warning."""
+    framework = _make_framework(tmp_path)
+    converted = _webserver(
+        tmp_path,
+        {
+            "build": {},
+            "dependencies": [{"name": "ESP32Async/AsyncTCP", "version": "^3.0"}],
+        },
+    )
+    with _emitting_converter(converted):
+        _resolve(framework)
+    assert "malformed" not in caplog.text
+
+
 def test_bundled_dependency_string_list_form(
     tmp_path: Path, caplog: pytest.LogCaptureFixture
 ) -> None: