Probe forced-on ccache directly so the warnings cannot contradict, carry the traceback on unexpected prefetch failures

esphome/espidf/framework.py

@@ -33,6 +33,7 @@ from esphome.framework_helpers import (
     run_command,
     run_command_ok,
     str_to_lst_of_str,
+    tool_version_runs,
 )
 from esphome.helpers import write_file_if_changed
 
@@ -1210,22 +1211,23 @@ def _ccache_env() -> dict[str, str]:
         return {"IDF_CCACHE_ENABLE": "0"}
     if idf_knob is True:
         # Forced on ignores the runnability verdict, but the outcome is
-        # worth saying out loud. Only the truly-missing case means idf.py
-        # compiles without ccache; a present-but-rejected binary (probe
-        # failure or shared opt-out) is still used, since idf.py does its
-        # own PATH lookup.
-        if resolve_ccache_path() is None:
-            if shutil.which("ccache") is None:
-                _LOGGER.warning(
-                    "IDF_CCACHE_ENABLE=1 but no ccache binary is on PATH; "
-                    "idf.py will compile without ccache"
-                )
-            else:
-                _LOGGER.warning(
-                    "IDF_CCACHE_ENABLE=1 forces ccache on even though it "
-                    "was rejected here (probe failure or "
-                    "ESPHOME_CCACHE_ENABLE=0); idf.py will use it anyway"
-                )
+        # worth saying out loud. Probed directly (not via the resolver,
+        # whose failure message says "compiling without ccache" -- exactly
+        # what forced-on does NOT do): only the truly-missing case means
+        # idf.py compiles without ccache; a broken binary is still used,
+        # since idf.py does its own PATH lookup.
+        if (ccache := shutil.which("ccache")) is None:
+            _LOGGER.warning(
+                "IDF_CCACHE_ENABLE=1 but no ccache binary is on PATH; "
+                "idf.py will compile without ccache"
+            )
+        else:
+            # The probe warns with this message iff the binary fails
+            tool_version_runs(
+                ccache,
+                "IDF_CCACHE_ENABLE=1 forces on the ccache at %s even though "
+                "it failed to run; idf.py will use it anyway",
+            )
     elif resolve_ccache_path() is None:
         # ESP-IDF silently skips ccache without the binary; export the
         # canonical off spelling so an unparsable inherited value (or a

esphome/platformio/registry.py

@@ -249,7 +249,7 @@ def prefetch_packages(
         else:
             # Anything else is a programming error that would otherwise
             # become a permanent silent no-op
-            _LOGGER.warning("Prefetch of %s failed: %r", name, err)
+            _LOGGER.warning("Prefetch of %s failed: %r", name, err, exc_info=err)
 
 
 def install_package(

tests/unit_tests/test_espidf_framework.py

@@ -1623,7 +1623,14 @@ def test_ccache_env_opt_in_with_working_binary(
     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:
+    with (
+        patch.dict("os.environ", {"IDF_CCACHE_ENABLE": "1"}, clear=True),
+        patch("esphome.espidf.framework.shutil.which", return_value=str(ccache)),
+        patch("esphome.espidf.framework.tool_version_runs", return_value=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
@@ -1635,10 +1642,14 @@ def test_ccache_env_opt_in_with_rejected_binary(
     # Forced on with a present-but-rejected binary: idf.py does its own
     # PATH lookup and uses it anyway; the warning must say so, not claim
     # the build runs without ccache.
+    # A present but non-executable file: the real probe fails and logs
+    # the forced-on message (patching the probe would silence it)
+    broken = tmp_path / "broken-ccache"
+    broken.touch()
     p1, p2, p3 = _ccache_patches(tmp_path, None, tmp_path / "build")
     with (
         patch.dict("os.environ", {"IDF_CCACHE_ENABLE": "1"}, clear=True),
-        patch("esphome.espidf.framework.shutil.which", return_value="/usr/bin/ccache"),
+        patch("esphome.espidf.framework.shutil.which", return_value=str(broken)),
         p1,
         p2,
         p3,
@@ -1646,6 +1657,9 @@ def test_ccache_env_opt_in_with_rejected_binary(
         env = _ccache_env()
     assert env["IDF_CCACHE_ENABLE"] == "1"
     assert "idf.py will use it anyway" in caplog.text
+    # Exactly one story: the resolver's contradictory "compiling without
+    # ccache" must not precede it
+    assert "compiling without ccache" not in caplog.text
 
 
 def test_ccache_env_honors_shared_esphome_opt_out(tmp_path: Path) -> None: