diff --git a/esphome/platformio/library.py b/esphome/platformio/library.py
index 6c472d3455..fc163964c8 100644
--- a/esphome/platformio/library.py
+++ b/esphome/platformio/library.py
@@ -739,6 +739,15 @@ def normalize_dependencies(
                     manifest_name,
                 )
                 continue
+            if "version" in entry and not isinstance(entry["version"], str):
+                # A container would raise from set.add(); an int fails
+                # opaquely inside the registry resolution
+                _LOGGER.warning(
+                    "Ignoring unrecognized dependency entry %r of %s",
+                    entry,
+                    manifest_name,
+                )
+                continue
             normalized.append(entry)
         return normalized
     if not isinstance(dependencies, (list, tuple)):
@@ -761,6 +770,15 @@ def normalize_dependencies(
                     manifest_name,
                 )
                 continue
+            if "version" in entry and not isinstance(entry["version"], str):
+                # A container would raise from set.add(); an int fails
+                # opaquely inside the registry resolution
+                _LOGGER.warning(
+                    "Ignoring unrecognized dependency entry %r of %s",
+                    entry,
+                    manifest_name,
+                )
+                continue
             normalized.append(entry)
         elif isinstance(entry, str) and entry:
             # PIO also accepts a bare list of names ("dependencies": ["Wire"])
@@ -948,8 +966,12 @@ def _content_lengths(urls: list[str]) -> list[int]:
     def head(url: str) -> int:
         try:
             resp = requests.head(url, timeout=10, allow_redirects=True)
+            if not resp.ok:
+                _LOGGER.debug("HEAD %s returned %s", url, resp.status_code)
+                return 0
             return int(resp.headers.get("content-length", 0))
-        except Exception:  # noqa: BLE001  # pylint: disable=broad-exception-caught
+        except Exception as err:  # noqa: BLE001  # pylint: disable=broad-exception-caught
+            _LOGGER.debug("HEAD %s failed: %s", url, err)
             return 0
 
     with ThreadPoolExecutor(max_workers=min(_DOWNLOAD_WORKERS, len(urls))) as ex:
@@ -1000,16 +1022,19 @@ def _prefetch_wave(
         tracker = progress.tracker()
         try:
             component.download(salt=salt, namespace=namespace, progress=tracker)
-        except Exception:  # noqa: BLE001  # pylint: disable=broad-exception-caught
+        except Exception as err:  # noqa: BLE001  # pylint: disable=broad-exception-caught
             # The sequential call below retries and reports the failure
+            _LOGGER.debug("Prefetch of %s failed: %s", component.name, err)
             tracker(0)
 
+    ex = ThreadPoolExecutor(max_workers=min(_DOWNLOAD_WORKERS, len(components)))
     try:
-        with ThreadPoolExecutor(
-            max_workers=min(_DOWNLOAD_WORKERS, len(components))
-        ) as ex:
-            list(ex.map(_fetch, components))
+        for future in [ex.submit(_fetch, component) for component in components]:
+            future.result()
     finally:
+        # On Ctrl-C drop the queued archives instead of downloading them
+        # all before the process can exit; in-flight ones still finish.
+        ex.shutdown(wait=True, cancel_futures=True)
         progress.done()
 
 
diff --git a/tests/unit_tests/test_platformio_library.py b/tests/unit_tests/test_platformio_library.py
index 6a578b4979..e36a7fa353 100644
--- a/tests/unit_tests/test_platformio_library.py
+++ b/tests/unit_tests/test_platformio_library.py
@@ -631,7 +631,7 @@ def test_lex_build_flags_dangling_flag_does_not_cross_entries(
 
 
 def test_prefetch_wave_downloads_registry_archives_in_parallel(
-    monkeypatch: pytest.MonkeyPatch,
+    setup_core, monkeypatch: pytest.MonkeyPatch
 ) -> None:
     """Registry archives in one wave download concurrently, deduped by URL;
     git/local sources and failures are left to the sequential call."""
@@ -670,12 +670,18 @@ def test_content_lengths_head_requests(monkeypatch: pytest.MonkeyPatch) -> None:
     def fake_head(url, timeout, allow_redirects):
         if "bad" in url:
             raise requests.ConnectionError("down")
-        return SimpleNamespace(headers={"content-length": "123"})
+        if "gone" in url:
+            return SimpleNamespace(ok=False, status_code=404, headers={})
+        return SimpleNamespace(ok=True, headers={"content-length": "123"})
 
     monkeypatch.setattr(
         lib.requests if hasattr(lib, "requests") else requests, "head", fake_head
     )
-    assert lib._content_lengths(["https://x/a", "https://x/bad"]) == [123, 0]
+    assert lib._content_lengths(["https://x/a", "https://x/bad", "https://x/gone"]) == [
+        123,
+        0,
+        0,
+    ]
 
 
 def test_prefetch_wave_cache_probe_failure_still_prefetches(
@@ -766,6 +772,11 @@ def test_normalize_dependencies_forms(caplog) -> None:
         {"": "1.0", "Wire": {"name": 123, "version": "1.0"}, "SPI": "*"}, "libx"
     ) == [{"name": "SPI", "owner": None, "version": "*"}]
     assert caplog.text.count("unrecognized dependency entry") == 5
+    # A container or numeric version would raise from set.add() or fail
+    # opaquely in the registry; both spellings warn and drop
+    assert normalize_dependencies({"Foo": ["1.0", "2.0"]}, "libx") == []
+    assert normalize_dependencies([{"name": "Foo", "version": 1}], "libx") == []
+    assert caplog.text.count("unrecognized dependency entry") == 7
 
 
 @pytest.mark.parametrize(