diff --git a/esphome/build_helpers/size_summary.py b/esphome/build_helpers/size_summary.py
index 5068e76d2d..72c429d095 100644
--- a/esphome/build_helpers/size_summary.py
+++ b/esphome/build_helpers/size_summary.py
@@ -17,3 +17,12 @@ def format_bar(used: int, total: int) -> str:
         f"[{progress:<{blocks}}] {pct_raw: 6.1%} "
         f"(used {used:d} bytes from {total:d} bytes)"
     )
+
+
+def print_size_line(label: str, used: int, total: int) -> None:
+    """One PlatformIO-format summary line (``RAM``/``Flash``).
+
+    The label padding is part of the format: ``script/ci_memory_impact_extract.py``
+    matches these lines verbatim.
+    """
+    print(f"{label + ':':<7}{format_bar(used, total)}")
diff --git a/esphome/espidf/size_summary.py b/esphome/espidf/size_summary.py
index 64f8edb98e..2be3634c69 100644
--- a/esphome/espidf/size_summary.py
+++ b/esphome/espidf/size_summary.py
@@ -28,7 +28,7 @@ import json
 import logging
 from pathlib import Path
 
-from esphome.build_helpers.size_summary import format_bar
+from esphome.build_helpers.size_summary import print_size_line
 
 _LOGGER = logging.getLogger(__name__)
 _SIZE_SUFFIXES = {"K": 1024, "M": 1024 * 1024}
@@ -89,7 +89,7 @@ def print_summary(size_json: Path, partitions_csv: Path | None) -> None:
     ram_used = ram_region.get("used")
     ram_total = ram_region.get("size")
     if ram_total and ram_used is not None:
-        print(f"RAM:   {format_bar(ram_used, ram_total)}")
+        print_size_line("RAM", ram_used, ram_total)
 
     image_size = data.get("image_size")
     if image_size is None or partitions_csv is None:
@@ -99,4 +99,4 @@ def print_summary(size_json: Path, partitions_csv: Path | None) -> None:
     except ValueError as e:
         _LOGGER.debug("Skipping Flash summary: %s", e)
         return
-    print(f"Flash: {format_bar(image_size, app_size)}")
+    print_size_line("Flash", image_size, app_size)
diff --git a/esphome/platformio/library.py b/esphome/platformio/library.py
index 4ae256444a..771570f872 100644
--- a/esphome/platformio/library.py
+++ b/esphome/platformio/library.py
@@ -48,20 +48,23 @@ DEFAULT_BUILD_SRC_FILTER = (
 DEFAULT_BUILD_SRC_DIRS = "src"
 DEFAULT_BUILD_INCLUDE_DIR = "include"
 DEFAULT_BUILD_FLAGS = []
-SRC_FILE_EXTENSIONS = [
-    ".c",
-    ".cpp",
-    ".cc",
-    ".cxx",
-    ".c++",
-    ".S",
-    ".spp",
-    ".SPP",
-    ".sx",
-    ".s",
-    ".asm",
-    ".ASM",
-]
+# Source suffix -> compiler kind, PlatformIO's CSUFFIXES/CXXSUFFIXES/ASSUFFIXES
+# split. Native build generators map the kind to their compile rules.
+SOURCE_KIND_FOR_SUFFIX: dict[str, str] = {
+    ".c": "c",
+    ".cpp": "cxx",
+    ".cc": "cxx",
+    ".cxx": "cxx",
+    ".c++": "cxx",
+    ".S": "asm",
+    ".spp": "asm",
+    ".SPP": "asm",
+    ".sx": "asm",
+    ".s": "asm",
+    ".asm": "asm",
+    ".ASM": "asm",
+}
+SRC_FILE_EXTENSIONS = list(SOURCE_KIND_FOR_SUFFIX)
 
 DOMAIN = "pio_components"
 
diff --git a/esphome/platformio/toolchain.py b/esphome/platformio/toolchain.py
index d76581d032..f454b81441 100644
--- a/esphome/platformio/toolchain.py
+++ b/esphome/platformio/toolchain.py
@@ -254,6 +254,7 @@ def _ccache_runs(ccache: str) -> bool:
             stdout=subprocess.DEVNULL,
             stderr=subprocess.DEVNULL,
             timeout=15,
+            close_fds=False,
         )
     except (OSError, subprocess.SubprocessError):
         _LOGGER.warning(
diff --git a/tests/unit_tests/build_helpers/test_size_summary.py b/tests/unit_tests/build_helpers/test_size_summary.py
index 2ccdb96613..231ae271b2 100644
--- a/tests/unit_tests/build_helpers/test_size_summary.py
+++ b/tests/unit_tests/build_helpers/test_size_summary.py
@@ -2,9 +2,21 @@
 
 from __future__ import annotations
 
-from esphome.build_helpers.size_summary import format_bar
+import pytest
+
+from esphome.build_helpers.size_summary import format_bar, print_size_line
 
 
 def test_format_bar_zero_total() -> None:
     """A zero total must not divide by zero."""
     assert format_bar(0, 0) == "[          ]   0.0% (used 0 bytes from 0 bytes)"
+
+
+def test_print_size_line_label_padding(capsys: pytest.CaptureFixture[str]) -> None:
+    """The label column is exactly what ci_memory_impact_extract.py greps."""
+    print_size_line("RAM", 47932, 180736)
+    print_size_line("Flash", 888511, 1835008)
+    out = capsys.readouterr().out.splitlines()
+    assert out[0].startswith("RAM:   [")
+    assert out[1].startswith("Flash: [")
+    assert "26.5% (used 47932 bytes from 180736 bytes)" in out[0]