Adjustments to Drag and Drop features, as well as theme features

components/board/category-lane.tsx

@@ -2,7 +2,7 @@
 
 import { useSortable } from "@dnd-kit/sortable";
 import { SortableContext, verticalListSortingStrategy } from "@dnd-kit/sortable";
-import { useDroppable } from "@dnd-kit/core";
+import { useDndContext, useDroppable } from "@dnd-kit/core";
 import { CSS } from "@dnd-kit/utilities";
 import { GripVertical, MoreVertical, Trash2 } from "lucide-react";
 
@@ -21,6 +21,19 @@ import type { CategoryDTO } from "@/types/board";
 export function CategoryLane({ category }: { category: CategoryDTO }) {
   const { removeCategory } = useBoard();
 
+  // The lane itself is sortable (so lanes can be reordered), which
+  // registers its *entire* rect -- header, cards, empty space, all of it --
+  // as a droppable. Dragging a group card over empty lane space then had
+  // two overlapping droppables to resolve against: this lane's own
+  // "category" droppable and the narrower "category-dropzone" below. With
+  // `closestCenter`, the much larger lane rect often won, so drop handling
+  // never saw a "group" or "category-dropzone" target and silently did
+  // nothing. Disabling this lane's droppable side while a *group* (not a
+  // lane) is being dragged removes it from collision detection entirely,
+  // leaving only the group cards and the dropzone as valid targets.
+  const { active } = useDndContext();
+  const isDraggingGroup = active?.data.current?.type === "group";
+
   const {
     setNodeRef,
     setActivatorNodeRef,
@@ -32,6 +45,7 @@ export function CategoryLane({ category }: { category: CategoryDTO }) {
   } = useSortable({
     id: category.id,
     data: { type: "category" },
+    disabled: { draggable: false, droppable: isDraggingGroup },
   });
 
   const { setNodeRef: setDropzoneRef } = useDroppable({
@@ -75,7 +89,7 @@ export function CategoryLane({ category }: { category: CategoryDTO }) {
           <DropdownMenuContent align="end">
             <DropdownMenuItem
               variant="destructive"
-              onSelect={() => removeCategory(category.id)}
+              onClick={() => removeCategory(category.id)}
             >
               <Trash2 className="size-4" />
               Delete category

components/board/group-card.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useState } from "react";
+import { useCallback, useState } from "react";
 import { useSortable } from "@dnd-kit/sortable";
 import { CSS } from "@dnd-kit/utilities";
 import { useTheme } from "next-themes";
@@ -47,10 +47,18 @@ export function GroupCard({ group }: { group: GroupDTO }) {
   // portaled Popover/Dialog content nested inside the card (the notes
   // editor, the "add to-do" popover). Wiring the same node as the
   // activator restores the target check.
-  function setCardRef(node: HTMLDivElement | null) {
+  //
+  // This must be memoized: a fresh function identity on every render makes
+  // React detach+reattach the ref each time, which during a drag (many
+  // re-renders as transform/isDragging change) resets dnd-kit's node
+  // registration and broke drop detection entirely.
+  const setCardRef = useCallback(
+    (node: HTMLDivElement | null) => {
       setNodeRef(node);
       setActivatorNodeRef(node);
-  }
+    },
+    [setNodeRef, setActivatorNodeRef]
+  );
 
   const color = getGroupColor(group.color);
   const borderColor = resolvedTheme === "dark" ? color.dark : color.light;
@@ -90,7 +98,7 @@ export function GroupCard({ group }: { group: GroupDTO }) {
               <DropdownMenuContent align="end">
                 <DropdownMenuItem
                   variant="destructive"
-                  onSelect={() => removeGroup(group.id, group.categoryId)}
+                  onClick={() => removeGroup(group.id, group.categoryId)}
                 >
                   <Trash2 className="size-4" />
                   Delete group

components/theme/theme-toggle.tsx

@@ -38,7 +38,7 @@ export function ThemeToggle({ collapsed }: { collapsed?: boolean }) {
       />
       <DropdownMenuContent align="start" side="right">
         {OPTIONS.map((option) => (
-          <DropdownMenuItem key={option.value} onSelect={() => setTheme(option.value)}>
+          <DropdownMenuItem key={option.value} onClick={() => setTheme(option.value)}>
             <option.icon className="size-4" />
             {option.label}
           </DropdownMenuItem>