diff --git a/script/determine-jobs.py b/script/determine-jobs.py
index 570b1a762c..a0e04a256e 100755
--- a/script/determine-jobs.py
+++ b/script/determine-jobs.py
@@ -273,6 +273,9 @@ def detect_memory_impact_config(
     building a merged configuration with all changed components (like
     test_build_components.py does) to get comprehensive memory analysis.
 
+    For core C++ file changes without component changes, runs a fallback
+    analysis using a representative component to measure the impact.
+
     Args:
         branch: Branch to compare against
 
@@ -289,7 +292,7 @@ def detect_memory_impact_config(
 
     # Find all changed components (excluding core and base bus components)
     changed_component_set: set[str] = set()
-    has_core_changes = False
+    has_core_cpp_changes = False
 
     for file in files:
         component = get_component_from_path(file)
@@ -297,22 +300,23 @@ def detect_memory_impact_config(
             # Skip base bus components as they're used across many builds
             if component not in BASE_BUS_COMPONENTS:
                 changed_component_set.add(component)
-        elif file.startswith("esphome/"):
-            # Core ESPHome files changed (not component-specific)
-            has_core_changes = True
+        elif file.startswith("esphome/") and file.endswith(CPP_FILE_EXTENSIONS):
+            # Core ESPHome C++ files changed (not component-specific)
+            # Only C++ files affect memory usage
+            has_core_cpp_changes = True
 
-    # If no components changed but core changed, test representative component
+    # If no components changed but core C++ changed, test representative component
     force_fallback_platform = False
-    if not changed_component_set and has_core_changes:
+    if not changed_component_set and has_core_cpp_changes:
         print(
-            f"Memory impact: No components changed, but core files changed. "
+            f"Memory impact: No components changed, but core C++ files changed. "
             f"Testing {MEMORY_IMPACT_FALLBACK_COMPONENT} component on {MEMORY_IMPACT_FALLBACK_PLATFORM}.",
             file=sys.stderr,
         )
         changed_component_set.add(MEMORY_IMPACT_FALLBACK_COMPONENT)
         force_fallback_platform = True  # Use fallback platform (most representative)
     elif not changed_component_set:
-        # No components and no core changes
+        # No components and no core C++ changes
         return {"should_run": "false"}
 
     # Find components that have tests and collect their supported platforms
diff --git a/tests/script/test_determine_jobs.py b/tests/script/test_determine_jobs.py
index b479fc03c5..7587dbee69 100644
--- a/tests/script/test_determine_jobs.py
+++ b/tests/script/test_determine_jobs.py
@@ -545,7 +545,7 @@ def test_detect_memory_impact_config_with_common_platform(tmp_path: Path) -> Non
 
 
 def test_detect_memory_impact_config_core_only_changes(tmp_path: Path) -> None:
-    """Test memory impact detection with core-only changes (no component changes)."""
+    """Test memory impact detection with core C++ changes (no component changes)."""
     # Create test directory structure with fallback component
     tests_dir = tmp_path / "tests" / "components"
 
@@ -554,7 +554,7 @@ def test_detect_memory_impact_config_core_only_changes(tmp_path: Path) -> None:
     api_dir.mkdir(parents=True)
     (api_dir / "test.esp32-idf.yaml").write_text("test: api")
 
-    # Mock changed_files to return only core files (no component files)
+    # Mock changed_files to return only core C++ files (no component files)
     with (
         patch.object(determine_jobs, "root_path", str(tmp_path)),
         patch.object(helpers, "root_path", str(tmp_path)),
@@ -574,6 +574,35 @@ def test_detect_memory_impact_config_core_only_changes(tmp_path: Path) -> None:
     assert result["use_merged_config"] == "true"
 
 
+def test_detect_memory_impact_config_core_python_only_changes(tmp_path: Path) -> None:
+    """Test that Python-only core changes don't trigger memory impact analysis."""
+    # Create test directory structure with fallback component
+    tests_dir = tmp_path / "tests" / "components"
+
+    # api component (fallback component) with esp32-idf test
+    api_dir = tests_dir / "api"
+    api_dir.mkdir(parents=True)
+    (api_dir / "test.esp32-idf.yaml").write_text("test: api")
+
+    # Mock changed_files to return only core Python files (no C++ files)
+    with (
+        patch.object(determine_jobs, "root_path", str(tmp_path)),
+        patch.object(helpers, "root_path", str(tmp_path)),
+        patch.object(determine_jobs, "changed_files") as mock_changed_files,
+    ):
+        mock_changed_files.return_value = [
+            "esphome/__main__.py",
+            "esphome/config.py",
+            "esphome/core/config.py",
+        ]
+        determine_jobs._component_has_tests.cache_clear()
+
+        result = determine_jobs.detect_memory_impact_config()
+
+    # Python-only changes should NOT trigger memory impact analysis
+    assert result["should_run"] == "false"
+
+
 def test_detect_memory_impact_config_no_common_platform(tmp_path: Path) -> None:
     """Test memory impact detection when components have no common platform."""
     # Create test directory structure