review: theme-owned drop mask token, overlay fade-in, stable gallery keys, close-button stacking, stale note defaults

packages/client/ui-attachment/src/DropOverlay.module.css

@@ -1,6 +1,7 @@
 /* Full-viewport drop invitation (DeepSeek Chat DragMask). pointer-events:
    none — the layer is decoration; drag events must keep hitting the page so
-   the owner's enter/leave count stays balanced. */
+   the owner's enter/leave count stays balanced. The frosted sheet color is
+   the theme's drop-mask alias (dark override lives with the theme owner). */
 .mask {
   position: fixed;
   inset: 0;
@@ -9,12 +10,20 @@
   align-items: center;
   justify-content: center;
   pointer-events: none;
-  background-color: rgba(255, 255, 255, 0.7);
+  background-color: var(--dsw-alias-bg-mask-drop);
   backdrop-filter: blur(10px);
+  animation: fade-in 160ms ease-out;
 }
 
-:global(body[data-ds-dark-theme]) .mask {
-  background-color: rgba(39, 39, 48, 0.7);
+@keyframes fade-in {
+  from { opacity: 0; }
+  to { opacity: 1; }
+}
+
+@media (prefers-reduced-motion: reduce) {
+  .mask {
+    animation: none;
+  }
 }
 
 .wrap {