MetadataSys.dll

Source	src/MetadataSys/
CMake target	MetadataSys
Type	Win32 COM DLL
Family	Platform services targets

At a glance

The property handler DLL: exposes media metadata through the Windows property system (propsys) so Explorer and other apps can read/write the metadata Movie Maker cares about (title, rating, tags, ...).

Public surface

From MetadataSys.def:

WLXPSGetItemPropertyHandler @1
DllCanUnloadNow            @2
DllGetClassObject          @3
DllRegisterServer          @4
DllUnregisterServer        @5

Implementation notes

• WLXPSGetItemPropertyHandler is the primary API entry (the "WLXPS" prefix = Windows Live eXPerience property system). It returns the handler for a given item's metadata.
• Links propsys (shell property system) — one of the few modules with a shell-system dependency beyond the common set.
• Metadata writes and thumbnail fallback behavior are a current reconstruction priority (see the TODO audit) — reads are real, some write/fallback paths remain guarded stubs.
• Property-store behavior is split: CMediaMetadataStore (the read-only extension store) returns STG_E_ACCESSDENIED from SetValue and persists nothing on Commit; write-back is instead delegated through CSafePropertyStore to the inner property handler when opened read-write (and fails with STG_E_ACCESSDENIED otherwise). The module itself performs no registry writes — the "Registry ops" category in Stub Design applies to modules such as WLXPhotoCinematic.

Testing

• Contract coverage for the handler entry + COM quartet in tests/mmr-python.
• Exercise app: apps/metadata-editor (submodule).

Analysis artifacts

analysis/MetadataSys/, analysis/RegRes/.