feat(packing): drag a category by its head to move it among the others

Categories showed in the order they were created, which a list kept per day
cannot undo once the days swap. A grip in each category's head band moves
the whole category onto another's place on desktop. A category has no
position of its own, it shows where its first item is, so the move reorders
the items as one block through the item reorder the list already has: no
new column, and the order reaches everyone the way a dragged item does. The
other view's categories keep their order.

client/src/components/Packing/PackingListPanelCategoryGroup.tsx

@@ -4,7 +4,7 @@ import { useToast } from '../shared/Toast'
 import { useTranslation } from '../../i18n'
 import {
   Trash2, Plus, ChevronDown, ChevronRight,
-  X, Pencil, Check, MoreHorizontal, CheckCheck, RotateCcw, UserPlus,
+  X, Pencil, Check, MoreHorizontal, CheckCheck, RotateCcw, UserPlus, GripVertical,
 } from 'lucide-react'
 import type { PackingItem, PackingBag } from '../../types'
 import { katColor } from './packingListPanel.helpers'
@@ -38,6 +38,18 @@ interface KategorieGruppeProps {
   // Off while the list is shown A-Z: a drop there would move an item in an order
   // the reader cannot see.
   reorderable?: boolean
+  // Moving the whole category among the others, wired by the list, which sees every
+  // card. `active` is true while any category is being dragged, so a dragged ITEM
+  // passing over a card is left to the item rows.
+  categoryDrag?: {
+    active: boolean
+    isDragging: boolean
+    isOver: boolean
+    onStart: () => void
+    onOver: () => void
+    onEnd: () => void
+    onDrop: () => void
+  }
   // Three-tier sharing (#858) — threaded down to each item's share control.
   currentUserId?: number
   onSetSharing?: (id: number, visibility: 'common' | 'personal' | 'shared', recipientIds: number[]) => void
@@ -46,7 +58,7 @@ interface KategorieGruppeProps {
   onLeave?: (id: number, userId: number) => void
 }
 
-export function KategorieGruppe({ kategorie, items, tripId, allCategories, onRename, onDeleteAll, onDeleteItem, onAddItem, assignees, tripMembers, onSetAssignees, bagTrackingEnabled, bags, onCreateBag, canEdit = true, allItems, onReorder, reorderable = true, currentUserId, onSetSharing, onClone, onJoin, onLeave }: KategorieGruppeProps) {
+export function KategorieGruppe({ kategorie, items, tripId, allCategories, onRename, onDeleteAll, onDeleteItem, onAddItem, assignees, tripMembers, onSetAssignees, bagTrackingEnabled, bags, onCreateBag, canEdit = true, allItems, onReorder, reorderable = true, categoryDrag, currentUserId, onSetSharing, onClone, onJoin, onLeave }: KategorieGruppeProps) {
   const [offen, setOffen] = useState(true)
   const [dragId, setDragId] = useState<number | null>(null)
   const [overId, setOverId] = useState<number | null>(null)
@@ -120,8 +132,9 @@ export function KategorieGruppe({ kategorie, items, tripId, allCategories, onRen
   return (
     // Shaped after the phone's category card: a tinted head band carrying the
     // name as written, the count, and the fold arrow on the far right.
-    <div style={{ marginBottom: 6, background: 'var(--bg-card)', borderRadius: 16, border: '1px solid var(--border-secondary)', overflow: 'visible' }}>
+    <CategoryDropFrame drag={categoryDrag}>
       <div style={{ display: 'flex', alignItems: 'center', gap: 8, paddingBlock: 11, paddingInlineEnd: 12, paddingInlineStart: 14, background: 'var(--bg-tertiary)', borderRadius: offen ? '15px 15px 0 0' : 15 }}>
+        <CategoryGrip drag={categoryDrag} kategorie={kategorie} label={t('packing.dragCategory')} />
         <span style={{ width: 10, height: 10, borderRadius: '50%', background: dot, flexShrink: 0 }} />
 
         {editingName && canEdit ? (
@@ -344,6 +357,48 @@ export function KategorieGruppe({ kategorie, items, tripId, allCategories, onRen
           ))}
         </div>
       )}
+    </CategoryDropFrame>
+  )
+}
+
+type CategoryDrag = NonNullable<KategorieGruppeProps['categoryDrag']>
+
+/**
+ * The card, and while a category is dragged its drop target. Captured, because
+ * the item rows stop their own drops from bubbling.
+ */
+function CategoryDropFrame({ drag, children }: { drag?: CategoryDrag; children: React.ReactNode }) {
+  const target = drag?.active ? drag : null
+  return (
+    <div
+      onDragOverCapture={target ? (e => { e.preventDefault(); e.dataTransfer.dropEffect = 'move'; target.onOver() }) : undefined}
+      onDropCapture={target ? (e => { e.preventDefault(); e.stopPropagation(); target.onDrop() }) : undefined}
+      style={{
+        marginBottom: 6, background: 'var(--bg-card)', borderRadius: 16, border: '1px solid var(--border-secondary)', overflow: 'visible',
+        opacity: drag?.isDragging ? 0.4 : 1,
+        boxShadow: drag?.isOver ? '0 0 0 2px var(--accent)' : 'none',
+        transition: 'opacity 0.15s, box-shadow 0.15s',
+      }}
+    >
+      {children}
     </div>
   )
 }
+
+/** The handle a category is dragged by, in the head band before its colour dot. */
+function CategoryGrip({ drag, kategorie, label }: { drag?: CategoryDrag; kategorie: string; label: string }) {
+  if (!drag) return null
+  return (
+    <span
+      draggable
+      role="button"
+      aria-label={label}
+      title={label}
+      onDragStart={e => { e.dataTransfer.effectAllowed = 'move'; e.dataTransfer.setData('text/plain', kategorie); drag.onStart() }}
+      onDragEnd={drag.onEnd}
+      style={{ cursor: 'grab', display: 'flex', alignItems: 'center', color: 'var(--text-faint)', flexShrink: 0, marginInlineStart: -6 }}
+    >
+      <GripVertical size={14} />
+    </span>
+  )
+}

client/src/components/Packing/PackingListPanelList.tsx

@@ -1,3 +1,4 @@
+import { useState } from 'react'
 import type { PackingState } from './usePackingListPanel'
 import { KategorieGruppe } from './PackingListPanelCategoryGroup'
 import EmptyState from '../shared/EmptyState'
@@ -7,8 +8,13 @@ export function PackingList(S: PackingState) {
     items, gruppiert, t, tripId, allCategories, handleRenameCategory, handleDeleteCategory, handleDeleteItem,
     handleAddItemToCategory, categoryAssignees, tripMembers, handleSetAssignees,
     bagTrackingEnabled, bags, handleCreateBagByName, canEdit, reorderPackingItems,
-    currentUserId, handleSetSharing, handleCloneItem, handleJoinItem, handleLeaveItem, sort,
+    currentUserId, handleSetSharing, handleCloneItem, handleJoinItem, handleLeaveItem, sort, moveCategory,
   } = S
+  // Which category is being dragged and which card it is over. Held here, above
+  // the cards, because the drag starts in one card and ends in another.
+  const [draggedCategory, setDraggedCategory] = useState<string | null>(null)
+  const [overCategory, setOverCategory] = useState<string | null>(null)
+  const endCategoryDrag = () => { setDraggedCategory(null); setOverCategory(null) }
   return (
     <div style={{ flex: 1, overflowY: 'auto', padding: '10px 0 16px' }}>
       {items.length === 0 ? (
@@ -40,6 +46,18 @@ export function PackingList(S: PackingState) {
               allItems={items}
               onReorder={(orderedIds) => reorderPackingItems(tripId, orderedIds)}
               reorderable={sort === 'manual'}
+              categoryDrag={canEdit ? {
+                active: draggedCategory !== null,
+                isDragging: draggedCategory === kat,
+                isOver: overCategory === kat && draggedCategory !== null && draggedCategory !== kat,
+                onStart: () => { setDraggedCategory(kat); setOverCategory(null) },
+                onOver: () => setOverCategory(kat),
+                onEnd: endCategoryDrag,
+                onDrop: () => {
+                  if (draggedCategory !== null) moveCategory(draggedCategory, kat)
+                  endCategoryDrag()
+                },
+              } : undefined}
               currentUserId={currentUserId}
               onSetSharing={handleSetSharing}
               onClone={handleCloneItem}

client/src/components/Packing/packingListModel.test.ts

@@ -6,6 +6,7 @@ import {
   groupPackingItems,
   isLastCustomItemInCategory,
   isPackingPlaceholder,
+  itemOrderWithCategoryMoved,
   packingCategoryOrder,
   packingItemWeight,
   packingProgress,
@@ -14,7 +15,7 @@ import {
 } from './packingListModel';
 import { PACKING_PLACEHOLDER_NAME } from './packingListPanel.constants';
 
-// FE-PACK-MODEL-001 to FE-PACK-MODEL-008
+// FE-PACK-MODEL-001 to FE-PACK-MODEL-009
 
 const shared = buildPackingItem({ id: 1, name: 'Tent', category: 'Camp', checked: 1 });
 const mine = buildPackingItem({ id: 2, name: 'Socks', category: 'Clothes', is_private: 1 });
@@ -76,4 +77,28 @@ describe('packingListModel', () => {
     expect(isPackingPlaceholder({ name: PACKING_PLACEHOLDER_NAME })).toBe(true);
     expect(isPackingPlaceholder({ name: 'Tent' })).toBe(false);
   });
+  it('FE-PACK-MODEL-009: moving a category moves its items as a block, the other view stays as it was', () => {
+    const day1 = buildPackingItem({ id: 11, name: 'Shirt', category: 'Day 1' });
+    const day2a = buildPackingItem({ id: 12, name: 'Shorts', category: 'Day 2' });
+    const own = buildPackingItem({ id: 13, name: 'Pills', category: 'Day 2', is_private: 1 });
+    const day3 = buildPackingItem({ id: 14, name: 'Jacket', category: 'Day 3' });
+    const day2b = buildPackingItem({ id: 15, name: 'Hat', category: 'Day 2' });
+    const items = [day1, day2a, own, day3, day2b];
+    const common = packingViewItems(items, 'common');
+
+    const order = itemOrderWithCategoryMoved(items, common, 'Day 3', 'Day 1', 'Other');
+    expect(order).toEqual([14, 11, 12, 15, 13]);
+    const moved = (order ?? []).flatMap((id) => items.filter((i) => i.id === id));
+    expect(packingCategoryOrder(packingViewItems(moved, 'common'), 'Other')).toEqual(['Day 3', 'Day 1', 'Day 2']);
+    expect(packingCategoryOrder(packingViewItems(moved, 'personal'), 'Other')).toEqual(['Day 2']);
+
+    expect(itemOrderWithCategoryMoved(items, common, 'Day 1', 'Day 3', 'Other')).toEqual([12, 15, 14, 11, 13]);
+  });
+
+  it('FE-PACK-MODEL-009b: nothing moves for the same category or one the view does not show', () => {
+    const items = [shared, stove, loose];
+    expect(itemOrderWithCategoryMoved(items, items, 'Camp', 'Camp', 'Other')).toBeNull();
+    expect(itemOrderWithCategoryMoved(items, items, 'Clothes', 'Camp', 'Other')).toBeNull();
+    expect(itemOrderWithCategoryMoved(items, items, 'Other', 'Camp', 'Other')).toEqual([4, 1, 3]);
+  });
 });

client/src/components/Packing/packingListModel.ts

@@ -25,6 +25,34 @@ export function packingCategoryOrder(viewItems: PackingItem[], defaultCategory:
   return seen;
 }
 
+/**
+ * The whole list's item order with category `from` moved to where `to` stands.
+ *
+ * A category has no position of its own: it shows where its first item is. So a
+ * category is moved by moving its items, as one block, through the item reorder
+ * the list already has; nothing new is stored, and the order reaches every device
+ * the way a dragged item does. The view's items come first, grouped in the new
+ * order with each group in its own order; the other view's items follow in theirs,
+ * which leaves that view's categories as they were. Null when nothing would move.
+ */
+export function itemOrderWithCategoryMoved(
+  items: PackingItem[],
+  viewItems: PackingItem[],
+  from: string,
+  to: string,
+  defaultCategory: string
+): number[] | null {
+  const order = packingCategoryOrder(viewItems, defaultCategory);
+  const fromIndex = order.indexOf(from);
+  const toIndex = order.indexOf(to);
+  if (fromIndex < 0 || toIndex < 0 || fromIndex === toIndex) return null;
+  order.splice(fromIndex, 1);
+  order.splice(toIndex, 0, from);
+  const inView = new Set(viewItems.map((i) => i.id));
+  const grouped = order.flatMap((cat) => viewItems.filter((i) => (i.category || defaultCategory) === cat));
+  return [...grouped, ...items.filter((i) => !inView.has(i.id))].map((i) => i.id);
+}
+
 export function packingStatusFiltered(items: PackingItem[], status: PackingStatusFilter): PackingItem[] {
   if (status === 'open') return items.filter((i) => !i.checked);
   if (status === 'done') return items.filter((i) => !!i.checked);

client/src/components/Packing/usePackingListPanel.ts

@@ -8,7 +8,7 @@ import { tripsApi } from '../../api/client'
 import { useAddonStore } from '../../store/addonStore'
 import type { PackingItem } from '../../types'
 import { parseImportLines, sortItemsByName } from './packingListPanel.helpers'
-import { groupPackingItems, packingCategoryOrder, packingProgress, packingViewItems } from './packingListModel'
+import { groupPackingItems, itemOrderWithCategoryMoved, packingCategoryOrder, packingProgress, packingViewItems } from './packingListModel'
 import { usePackingBags } from './usePackingBags'
 import { usePackingCategoryAssignees } from './usePackingCategoryAssignees'
 import { usePackingImport } from './usePackingImport'
@@ -106,6 +106,13 @@ export function usePackingList({ tripId, items, openImportSignal = 0, addCategor
 
   const { checked: abgehakt, pct: fortschritt } = packingProgress(viewItems)
 
+  // A category dropped onto another takes its place; the slice reorders
+  // optimistically and rolls back with a toast of its own.
+  const moveCategory = (from: string, to: string) => {
+    const orderedIds = itemOrderWithCategoryMoved(items, viewItems, from, to, t('packing.defaultCategory'))
+    if (orderedIds) void reorderPackingItems(tripId, orderedIds)
+  }
+
   const {
     addingCategory, setAddingCategory, newCategoryName: newCatName, setNewCategoryName: setNewCatName,
     addItemToCategory: handleAddItemToCategory, deleteItem: handleDeleteItem, addNewCategory: handleAddNewCategory,
@@ -213,7 +220,7 @@ export function usePackingList({ tripId, items, openImportSignal = 0, addCategor
     handleSetSharing, handleCloneItem, handleJoinItem, handleLeaveItem,
     tripId, items, inlineHeader, t, canEdit, isAdmin, font, reorderPackingItems,
     filter, setFilter, sort, setSort, addingCategory, setAddingCategory, newCatName, setNewCatName,
-    tripMembers, categoryAssignees, handleSetAssignees, allCategories, gruppiert, abgehakt, fortschritt,
+    tripMembers, categoryAssignees, handleSetAssignees, allCategories, gruppiert, abgehakt, fortschritt, moveCategory,
     handleAddItemToCategory, handleAddNewCategory, handleRenameCategory, handleDeleteCategory, handleDeleteItem, handleClearChecked,
     bagTrackingEnabled, bags, unassignedWeightGrams, serverWeightsFresh, newBagName, setNewBagName, showAddBag, setShowAddBag, showBagModal, setShowBagModal,
     handleCreateBag, handleCreateBagByName, handleDeleteBag, handleUpdateBag, handleSetBagMembers,