Name malformed registry elements, parse ESPHOME_CCACHE_ENABLE strictly, require a package layout check

Registry version and file entries that are not dicts now raise the same
Unexpected-response error as the other shape guards instead of an
AttributeError traceback. install_package rejects an empty expect so
every install is layout-validated before the marker is written.
ESPHOME_CCACHE_ENABLE values outside 1/true/yes/on and 0/false/no/off
warn and are treated as unset instead of bool(str) flipping them to
enabled. The strip_win_long_path_prefix test moved next to the function
in test_framework_helpers, and a stale comment naming its old module is
fixed.

esphome/build_helpers/ccache.py

@@ -54,16 +54,28 @@ def resolve_ccache_path() -> str | None:
 
     Shared policy for every backend: on by default when a runnable ccache is
     on PATH, ``ESPHOME_CCACHE_ENABLE=0`` opts out, and an explicit ``=1``
-    warns when no binary is found and skips the runnability probe. The
+    warns when no binary is found and skips the runnability probe;
+    any other value warns and is treated as unset. The
     Windows extended-length prefix is stripped before probing so the probe
     validates the exact string the build will execute (#18399).
     """
     import shutil
 
-    from esphome.helpers import get_bool_env
-
-    explicit = "ESPHOME_CCACHE_ENABLE" in os.environ
-    if explicit and not get_bool_env("ESPHOME_CCACHE_ENABLE"):
+    # Strict parse: bool(str) truthiness would flip "no"/"off" to enabled
+    # and silently skip the probe
+    raw = os.environ.get("ESPHOME_CCACHE_ENABLE")
+    explicit: bool | None = None
+    if raw is not None:
+        lowered = raw.strip().lower()
+        if lowered in ("1", "true", "yes", "on"):
+            explicit = True
+        elif lowered in ("0", "false", "no", "off"):
+            explicit = False
+        else:
+            _LOGGER.warning(
+                "Ignoring unrecognized ESPHOME_CCACHE_ENABLE=%r; use 1 or 0", raw
+            )
+    if explicit is False:
         return None
     ccache = shutil.which("ccache")
     if ccache is None:

esphome/platformio/registry.py

@@ -79,6 +79,10 @@ def registry_download(package: str, version: str) -> tuple[str, str, int | None]
             f"Unexpected package registry response for {package}: {str(data)[:200]}"
         )
     for ver in versions:
+        if not isinstance(ver, dict):
+            raise EsphomeError(
+                f"Unexpected package registry response for {package}: {str(data)[:200]}"
+            )
         if ver.get("name") != version:
             continue
         files = ver.get("files")
@@ -87,6 +91,11 @@ def registry_download(package: str, version: str) -> tuple[str, str, int | None]
                 f"Unexpected package registry response for {package}: {str(ver)[:200]}"
             )
         for file in files:
+            if not isinstance(file, dict):
+                raise EsphomeError(
+                    f"Unexpected package registry response for {package}: "
+                    f"{str(ver)[:200]}"
+                )
             # Only a MISSING key means "any system"; an explicitly empty
             # list must not match (a wrong-architecture download would be
             # cached as a good install). A bare string would make ``in`` a
@@ -133,6 +142,10 @@ def install_package(
     substitution) is trusted as configured. ``downloads_dir`` holds the
     archive between runs so an interrupted download resumes.
     """
+    if not expect:
+        # Layout validation before marker.touch() is the only guard against
+        # caching a truncated mirror archive as a good install
+        raise ValueError("install_package requires a non-empty expect")
     marker = dest / ".esphome_extracted"
     if marker.is_file():
         return