diff --git a/esphome/build_gen/arduino8266.py b/esphome/build_gen/arduino8266.py
index d8ebf92a53..d93c1b7943 100644
--- a/esphome/build_gen/arduino8266.py
+++ b/esphome/build_gen/arduino8266.py
@@ -28,6 +28,7 @@ from typing import TYPE_CHECKING, NamedTuple
 
 from esphome.arduino8266.framework import toolchain_tool
 from esphome.build_helpers.ccache import effective_ccache_basedir
+from esphome.build_helpers.idedata import is_joined_include
 from esphome.build_helpers.ninja import (
     escape as _e,
     quote_path as _q,
@@ -1211,9 +1212,9 @@ def write_project(paths: InstalledPaths, ccache: str | None) -> bool:
                     "build_src_flags has a trailing '-include' with no header"
                 )
             src_includes.append(header)
-        elif tok.startswith("-include") and not tok.startswith("-include-"):
-            # Joined spelling; left in src_other it would precede the pch
-            # include and silently defeat the .gch
+        elif is_joined_include(tok):
+            # Left in src_other it would precede the pch include and
+            # silently defeat the .gch
             src_includes.append(tok[len("-include") :])
         else:
             src_other.append(_shell_token(tok))
diff --git a/esphome/build_helpers/idedata.py b/esphome/build_helpers/idedata.py
index 4f6b7f36fc..930fe983a6 100644
--- a/esphome/build_helpers/idedata.py
+++ b/esphome/build_helpers/idedata.py
@@ -161,6 +161,15 @@ def is_launcher(token: str) -> bool:
     return Path(token).stem.lower() in _LAUNCHER_STEMS
 
 
+def is_joined_include(tok: str) -> bool:
+    """The joined ``-includefoo.h`` spelling; excludes clang's -include-pch."""
+    return (
+        tok.startswith("-include")
+        and tok != "-include"
+        and not tok.startswith("-include-")
+    )
+
+
 def parse_entry(
     entry: dict, launcher: str | None = None
 ) -> tuple[str, list[str], list[str], list[str]]:
@@ -201,9 +210,7 @@ def parse_entry(
     for tok in it:
         if tok in ("-c", "-o"):
             next(it, None)  # drop the flag and its argument (input/output)
-        elif tok == "-include" or (
-            tok.startswith("-include") and not tok.startswith("-include-")
-        ):
+        elif tok == "-include" or is_joined_include(tok):
             # Re-anchor only names next to the compile (the pch); a name
             # meant for the -I chain must stay untouched
             raw = next(it, "") if tok == "-include" else tok[len("-include") :]
diff --git a/tests/unit_tests/build_helpers/test_pch.py b/tests/unit_tests/build_helpers/test_pch.py
index 0fc2378288..010c93bb66 100644
--- a/tests/unit_tests/build_helpers/test_pch.py
+++ b/tests/unit_tests/build_helpers/test_pch.py
@@ -205,3 +205,14 @@ def test_include_closure_walks_angle_includes_under_src(tmp_path: Path) -> None:
     (tmp_path / "local.h").write_text("")
     closure = pch._include_closure(tmp_path, ["a.h"])
     assert set(closure) == {"a.h", "local.h"}
+
+
+def test_ccache_pch_env_warns_on_falsy_extsum(
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    """A user CCACHE_PCH_EXTSUM=false makes ccache hash the .gch bytes."""
+    pch.mark_pch_emitted()
+    with patch.dict(os.environ, {"CCACHE_PCH_EXTSUM": "false"}, clear=True):
+        env = pch.ccache_pch_env()
+    assert "CCACHE_PCH_EXTSUM" not in env
+    assert "disables pch caching" in caplog.text