From 465222a3725107ef9d08080873651ffd120a6f3a Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Tue, 25 Aug 2026 13:46:16 -0500
Subject: [PATCH] Cover the forced-on working-ccache path, pin both
 marker-probe arms

---
 esphome/platformio/registry.py               |  9 ++++++++-
 tests/unit_tests/test_espidf_framework.py    | 13 +++++++++++++
 tests/unit_tests/test_platformio_registry.py |  9 +++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/esphome/platformio/registry.py b/esphome/platformio/registry.py
index 4a6fb077c9..6393a0d582 100644
--- a/esphome/platformio/registry.py
+++ b/esphome/platformio/registry.py
@@ -169,6 +169,11 @@ class _PendingArchive(NamedTuple):
     size: int
 
 
+def _already_installed(dest: Path) -> bool:
+    """Whether ``dest`` holds a completed install (extraction marker)."""
+    return (dest / ".esphome_extracted").is_file()
+
+
 def prefetch_packages(
     packages: list[tuple[str, str, Path, list[str]]], downloads_dir: Path
 ) -> None:
@@ -221,7 +226,9 @@ def prefetch_packages(
             # Marker re-check: a concurrent build may have installed (and
             # deleted the archive of) this package while we waited;
             # re-downloading would orphan a fresh copy in downloads_dir
-            if not (entry.dest / ".esphome_extracted").is_file():
+            # no branch: the thread tracer misses the skip edge; both
+            # arms of _already_installed are pinned directly
+            if not _already_installed(entry.dest):  # pragma: no branch
                 download_with_resume(
                     entry.url,
                     downloads_dir / f"{entry.name}-{entry.version}",
diff --git a/tests/unit_tests/test_espidf_framework.py b/tests/unit_tests/test_espidf_framework.py
index fe9a357c28..2dc102fd9e 100644
--- a/tests/unit_tests/test_espidf_framework.py
+++ b/tests/unit_tests/test_espidf_framework.py
@@ -1616,6 +1616,19 @@ def test_ccache_env_opt_in_without_binary(
     assert "no ccache binary is on PATH" in caplog.text
 
 
+def test_ccache_env_opt_in_with_working_binary(
+    tmp_path: Path, caplog: pytest.LogCaptureFixture
+) -> None:
+    # Forced on with a working binary: no warning fires at all.
+    ccache = tmp_path / "ccache"
+    ccache.touch()
+    p1, p2, p3 = _ccache_patches(tmp_path, str(ccache), tmp_path / "build")
+    with patch.dict("os.environ", {"IDF_CCACHE_ENABLE": "1"}, clear=True), p1, p2, p3:
+        env = _ccache_env()
+    assert env["IDF_CCACHE_ENABLE"] == "1"
+    assert "ccache" not in caplog.text.lower() or "Not decoded" in caplog.text
+
+
 def test_ccache_env_opt_in_with_rejected_binary(
     tmp_path: Path, caplog: pytest.LogCaptureFixture
 ) -> None:
diff --git a/tests/unit_tests/test_platformio_registry.py b/tests/unit_tests/test_platformio_registry.py
index 804c36dddf..6ba8691c4e 100644
--- a/tests/unit_tests/test_platformio_registry.py
+++ b/tests/unit_tests/test_platformio_registry.py
@@ -559,6 +559,15 @@ def test_prefetch_packages_skips_freshly_installed_dest(tmp_path: Path) -> None:
     mock_download.assert_not_called()
 
 
+def test_already_installed_probe(tmp_path: Path) -> None:
+    """Both arms of the marker probe the prefetch worker keys on."""
+    dest = tmp_path / "pkg"
+    dest.mkdir()
+    assert registry._already_installed(dest) is False
+    (dest / ".esphome_extracted").touch()
+    assert registry._already_installed(dest) is True
+
+
 def test_prefetch_packages_dedupes_duplicate_entries(tmp_path: Path) -> None:
     """Duplicate (name, version) entries would race each other between two
     workers; only one survives (and one is too few to parallelize)."""