[fix] avoid false Windows privacy screen obstruction failures

apps/desktop/src/platform/windows/privacy/privacy_backend_win.cpp

@@ -21,6 +21,7 @@
 #include "privacy_input_guard.h"
 #include "privacy_probe_pattern.h"
 #include "privacy_probe_renderer.h"
+#include "privacy_window_visibility.h"
 #include "rd_log.h"
 
 #ifndef WDA_EXCLUDEFROMCAPTURE
@@ -379,6 +380,7 @@ class WindowsPrivacyBackend final : public PrivacyBackend {
           continue;
         if (GetWindowRect(above, &bounds) &&
             IntersectRect(&intersection, &bounds, &w.rect)) {
+          if (IsNonObstructingPrivacyWindow(above, bounds)) continue;
           char window_class[128]{};
           DWORD process_id = 0;
           GetClassNameA(above, window_class, sizeof(window_class));
@@ -387,16 +389,19 @@ class WindowsPrivacyBackend final : public PrivacyBackend {
           if (above != last_obstruction_ ||
               now - last_obstruction_log_ >= 1000) {
             LOG_WARN(
-                "Privacy cover obstructed: class={}, process={}; "
+                "Potential privacy cover overlap: class={}, process={}, "
+                "band={}, bounds=({}, {})-({}, {}), exstyle=0x{:x}; "
                 "remote operation paused",
-                window_class, process_id);
+                window_class, process_id, above_band, bounds.left, bounds.top,
+                bounds.right, bounds.bottom,
+                GetWindowLongPtrW(above, GWL_EXSTYLE));
             last_obstruction_ = above;
             last_obstruction_log_ = now;
           }
-          // A higher-band/system window cannot be repaired by raising an
-          // ordinary cover. Retain protection and require explicit recovery.
+          // HWND order cannot prove compositor order, but this window may
+          // display content. Retain protection and require explicit recovery.
           return {
-              "A system or higher-band window overrides privacy coverage; "
+              "A visible window may overlap privacy coverage; "
               "remote operation paused. Turn privacy off to recover.",
               false};
         }

apps/desktop/src/platform/windows/privacy/privacy_window_visibility.h

@@ -0,0 +1,42 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2026-09-11
+ * Copyright (c) 2026 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _PRIVACY_WINDOW_VISIBILITY_H_
+#define _PRIVACY_WINDOW_VISIBILITY_H_
+
+#include <Windows.h>
+
+#include <cstdint>
+
+namespace crossdesk {
+
+// Called for a visible foreign window whose full bounds intersect a cover.
+// Inspect it on every check: an OSD helper can grow into a content window.
+inline bool IsNonObstructingPrivacyWindow(HWND window, const RECT& bounds) {
+  const auto styles = GetWindowLongPtrW(window, GWL_EXSTYLE);
+  if (!(styles & WS_EX_LAYERED)) return false;
+
+  BYTE alpha = 0;
+  DWORD flags = 0;
+  // WS_EX_TRANSPARENT alone does not imply invisible pixels. Likewise,
+  // UpdateLayeredWindow windows can reject this query; failure proves nothing.
+  if (GetLayeredWindowAttributes(window, nullptr, &alpha, &flags) &&
+      (flags & LWA_ALPHA) && alpha == 0)
+    return true;
+
+  constexpr LONG_PTR helper_styles =
+      WS_EX_TOOLWINDOW | WS_EX_NOACTIVATE | WS_EX_TRANSPARENT;
+  const auto width = static_cast<int64_t>(bounds.right) - bounds.left;
+  const auto height = static_cast<int64_t>(bounds.bottom) - bounds.top;
+  // Single-pixel, nonactivating OSD placeholders cannot display meaningful
+  // desktop content. Use the whole window, never its clipped intersection;
+  // larger OSDs and windows with unknown opacity still require coverage checks.
+  return (styles & helper_styles) == helper_styles && width == 1 && height == 1;
+}
+
+}  // namespace crossdesk
+
+#endif  // _PRIVACY_WINDOW_VISIBILITY_H_