fix: restore scroll position in mobile Plan and Places sidebars on reopen (issue #932)

Both DayPlanSidebar and PlacesSidebar have their own internal scroll
containers (overflowY: auto). Scroll events don't bubble, so previous
attempts that tracked scrollTop on the outer portal div never fired.

Each sidebar now accepts initialScrollTop and onScrollTopChange props.
The internal scroll container saves its scrollTop via onScrollTopChange
on every scroll event, and restores it via useLayoutEffect on mount
(before the browser paints, so no visible flash).

TripPlannerPage holds the saved values in refs (mobilePlanScrollTopRef,
mobilePlacesScrollTopRef) and passes them through on each portal mount.

client/src/components/Planner/DayPlanSidebar.tsx

@@ -2,7 +2,7 @@
 interface DragDataPayload { placeId?: string; assignmentId?: string; noteId?: string; reservationId?: string; fromDayId?: string; phase?: 'single' | 'start' | 'middle' | 'end' }
 declare global { interface Window { __dragData: DragDataPayload | null } }
 
-import React, { useState, useEffect, useRef, useMemo } from 'react'
+import React, { useState, useEffect, useLayoutEffect, useRef, useMemo } from 'react'
 import ReactDOM from 'react-dom'
 import { ChevronDown, ChevronRight, ChevronUp, ChevronsDownUp, ChevronsUpDown, Navigation, RotateCcw, ExternalLink, Clock, Pencil, GripVertical, Ticket, Plus, FileText, Check, Trash2, Info, MapPin, Star, Heart, Camera, Lightbulb, Flag, Bookmark, Train, Bus, Plane, Car, Ship, Coffee, ShoppingBag, AlertTriangle, FileDown, Lock, Hotel, Utensils, Users, Undo2, X, Route as RouteIcon } from 'lucide-react'
 
@@ -191,6 +191,8 @@ interface DayPlanSidebarProps {
   onEditTransport?: (reservation: Reservation) => void
   onEditReservation?: (reservation: Reservation) => void
   onAddBookingToAssignment?: (dayId: number, assignmentId: number) => void
+  initialScrollTop?: number
+  onScrollTopChange?: (top: number) => void
 }
 
 const DayPlanSidebar = React.memo(function DayPlanSidebar({
@@ -219,6 +221,8 @@ const DayPlanSidebar = React.memo(function DayPlanSidebar({
   onEditTransport,
   onEditReservation,
   onAddBookingToAssignment,
+  initialScrollTop,
+  onScrollTopChange,
 }: DayPlanSidebarProps) {
   const toast = useToast()
   const { t, language, locale } = useTranslation()
@@ -271,6 +275,12 @@ const DayPlanSidebar = React.memo(function DayPlanSidebar({
   } | null>(null)
   const inputRef = useRef(null)
   const dragDataRef = useRef(null)
+  const scrollContainerRef = useRef<HTMLDivElement | null>(null)
+  useLayoutEffect(() => {
+    if (scrollContainerRef.current && initialScrollTop) {
+      scrollContainerRef.current.scrollTop = initialScrollTop
+    }
+  }, [])
   const initedTransportIds = useRef(new Set<number>()) // Speichert Drag-Daten als Backup (dataTransfer geht bei Re-Render verloren)
   // Remember which assignment we last auto-scrolled into view so we don't
   // keep yanking the user back whenever they scroll away while the same
@@ -1118,7 +1128,7 @@ const DayPlanSidebar = React.memo(function DayPlanSidebar({
       </div>
 
       {/* Tagesliste */}
-      <div className={`scroll-container${draggingId ? '' : ' trek-stagger'}`} style={{ flex: 1, overflowY: 'auto', minHeight: 0 }}>
+      <div className={`scroll-container${draggingId ? '' : ' trek-stagger'}`} style={{ flex: 1, overflowY: 'auto', minHeight: 0 }} ref={scrollContainerRef} onScroll={(e) => onScrollTopChange?.((e.currentTarget as HTMLElement).scrollTop)}>
         {days.map((day, index) => {
           const isSelected = selectedDayId === day.id
           const isExpanded = expandedDays.has(day.id)

client/src/components/Planner/PlacesSidebar.tsx

@@ -1,6 +1,6 @@
 import React from 'react'
 import ReactDOM from 'react-dom'
-import { useState, useMemo, useEffect, useRef, useCallback } from 'react'
+import { useState, useMemo, useEffect, useLayoutEffect, useRef, useCallback } from 'react'
 import { Search, Plus, X, CalendarDays, Pencil, Trash2, ExternalLink, Navigation, Upload, ChevronDown, Check, MapPin, Eye, Route } from 'lucide-react'
 import PlaceAvatar from '../shared/PlaceAvatar'
 import { getCategoryIcon } from '../shared/categoryIcons'
@@ -34,6 +34,8 @@ interface PlacesSidebarProps {
   onCategoryFilterChange?: (categoryIds: Set<string>) => void
   onPlacesFilterChange?: (filter: string) => void
   pushUndo?: (label: string, undoFn: () => Promise<void> | void) => void
+  initialScrollTop?: number
+  onScrollTopChange?: (top: number) => void
 }
 
 interface MemoPlaceRowProps {
@@ -145,6 +147,7 @@ const MemoPlaceRow = React.memo(function MemoPlaceRow({
 const PlacesSidebar = React.memo(function PlacesSidebar({
   tripId, places, categories, assignments, selectedDayId, selectedPlaceId,
   onPlaceClick, onAddPlace, onAssignToDay, onEditPlace, onDeletePlace, onBulkDeletePlaces, onBulkDeleteConfirm, days, isMobile, onCategoryFilterChange, onPlacesFilterChange, pushUndo,
+  initialScrollTop, onScrollTopChange,
 }: PlacesSidebarProps) {
   const { t } = useTranslation()
   const toast = useToast()
@@ -159,6 +162,12 @@ const PlacesSidebar = React.memo(function PlacesSidebar({
   const [sidebarDropFile, setSidebarDropFile] = useState<File | null>(null)
   const [sidebarDragOver, setSidebarDragOver] = useState(false)
   const sidebarDragCounter = useRef(0)
+  const scrollContainerRef = useRef<HTMLDivElement | null>(null)
+  useLayoutEffect(() => {
+    if (scrollContainerRef.current && initialScrollTop) {
+      scrollContainerRef.current.scrollTop = initialScrollTop
+    }
+  }, [])
 
   const handleSidebarDragEnter = (e: React.DragEvent) => {
     if (!canEditPlaces) return
@@ -636,7 +645,7 @@ const PlacesSidebar = React.memo(function PlacesSidebar({
       )}
 
       {/* Liste */}
-      <div className="trek-stagger" style={{ flex: 1, overflowY: 'auto', minHeight: 0 }}>
+      <div className="trek-stagger" style={{ flex: 1, overflowY: 'auto', minHeight: 0 }} ref={scrollContainerRef} onScroll={(e) => onScrollTopChange?.((e.currentTarget as HTMLElement).scrollTop)}>
         {filtered.length === 0 ? (
           <div style={{ display: 'flex', flexDirection: 'column', alignItems: 'center', padding: '40px 16px', gap: 8 }}>
             <span style={{ fontSize: 13, color: 'var(--text-faint)' }}>

client/src/pages/TripPlannerPage.test.tsx

@@ -1474,6 +1474,56 @@ describe('TripPlannerPage', () => {
     });
   });
 
+  describe('FE-PAGE-PLANNER-051: Mobile Plan sidebar stays mounted after onPlaceClick (issue #932)', () => {
+    it('does not unmount the mobile Plan portal when a place is tapped, preserving scroll position', async () => {
+      vi.useFakeTimers();
+      Object.defineProperty(window, 'innerWidth', { writable: true, configurable: true, value: 375 });
+
+      const place = buildPlace({ id: 1, trip_id: 42, lat: 48.8566, lng: 2.3522 });
+      const assignment = buildAssignment({ id: 10, day_id: 99, place, order_index: 0 });
+      seedTripStore({ id: 42 });
+      seedStore(useTripStore, {
+        places: [place],
+        assignments: { '99': [assignment] },
+      } as any);
+
+      renderPlannerPage(42);
+      act(() => { vi.runAllTimers(); });
+      vi.useRealTimers();
+
+      await waitFor(() => {
+        expect(screen.getByTestId('day-plan-sidebar')).toBeInTheDocument();
+      });
+
+      // Open the mobile Plan portal via the bottom-nav Plan button (selector mirrors FE-PAGE-PLANNER-049).
+      const mobilePlanBtn = Array.from(document.body.querySelectorAll('button')).find(
+        b => b.textContent === 'Plan' && !b.getAttribute('title'),
+      );
+      expect(mobilePlanBtn).toBeTruthy();
+      await act(async () => { fireEvent.click(mobilePlanBtn!); });
+
+      await waitFor(() => {
+        expect(screen.getAllByTestId('day-plan-sidebar').length).toBe(2);
+      });
+
+      // The mock factory overwrites capturedDayPlanSidebarProps on each mount,
+      // so current holds the mobile portal instance's props.
+      const mobileOnPlaceClick = capturedDayPlanSidebarProps.current.onPlaceClick;
+      expect(typeof mobileOnPlaceClick).toBe('function');
+
+      await act(async () => {
+        mobileOnPlaceClick(place.id, assignment.id);
+      });
+
+      // Invariant: portal must NOT unmount — both instances persist.
+      // Pre-fix: collapses to 1 (setMobileSidebarOpen(null) destroyed scroll container).
+      // Post-fix: stays at 2, browser preserves scrollTop on the living DOM node.
+      expect(screen.getAllByTestId('day-plan-sidebar').length).toBe(2);
+
+      Object.defineProperty(window, 'innerWidth', { writable: true, configurable: true, value: 1024 });
+    });
+  });
+
   describe('FE-PAGE-PLANNER-037: onExpandedDaysChange covers mapPlaces hidden logic', () => {
     it('calls onExpandedDaysChange to trigger mapPlaces hidden set computation', async () => {
       vi.useFakeTimers();

client/src/pages/TripPlannerPage.tsx

@@ -272,6 +272,8 @@ export default function TripPlannerPage(): React.ReactElement | null {
   const [fitKey, setFitKey] = useState<number>(0)
   const initialFitTripId = useRef<number | null>(null)
   const [mobileSidebarOpen, setMobileSidebarOpen] = useState<'left' | 'right' | null>(null)
+  const mobilePlanScrollTopRef = useRef<number>(0)
+  const mobilePlacesScrollTopRef = useRef<number>(0)
   const [deletePlaceId, setDeletePlaceId] = useState<number | null>(null)
   const [deletePlaceIds, setDeletePlaceIds] = useState<number[] | null>(null)
 
@@ -1114,8 +1116,8 @@ export default function TripPlannerPage(): React.ReactElement | null {
                   </div>
                   <div style={{ flex: 1, overflow: 'auto' }}>
                     {mobileSidebarOpen === 'left'
-                      ? <DayPlanSidebar tripId={tripId} trip={trip} days={days} places={places} categories={categories} assignments={assignments} selectedDayId={selectedDayId} selectedPlaceId={selectedPlaceId} selectedAssignmentId={selectedAssignmentId} onSelectDay={(id) => { handleSelectDay(id); setMobileSidebarOpen(null) }} onPlaceClick={(placeId, assignmentId) => { handlePlaceClick(placeId, assignmentId); setMobileSidebarOpen(null) }} onReorder={handleReorder} onUpdateDayTitle={handleUpdateDayTitle} onAssignToDay={handleAssignToDay} onRouteCalculated={(r) => { if (r) { setRoute(r.coordinates); setRouteInfo({ distance: r.distanceText, duration: r.durationText }) } }} reservations={reservations} visibleConnectionIds={visibleConnections} onToggleConnection={toggleConnection} onAddReservation={(dayId) => { setEditingReservation(null); tripActions.setSelectedDay(dayId); setShowReservationModal(true); setMobileSidebarOpen(null) }} onAddPlace={() => { setEditingPlace(null); setShowPlaceForm(true); setMobileSidebarOpen(null) }} onDayDetail={(day) => { setShowDayDetail(day); setSelectedPlaceId(null); selectAssignment(null); setMobileSidebarOpen(null) }} accommodations={tripAccommodations} onNavigateToFiles={() => { setMobileSidebarOpen(null); handleTabChange('dateien') }} onExpandedDaysChange={setExpandedDayIds} pushUndo={pushUndo} canUndo={canUndo} lastActionLabel={lastActionLabel} onUndo={handleUndo} onEditTransport={can('day_edit', trip) ? (reservation) => { setEditingTransport(reservation); setTransportModalDayId(reservation.day_id ?? null); setShowTransportModal(true); setMobileSidebarOpen(null) } : undefined} onEditReservation={can('reservation_edit', trip) ? (r) => { setEditingReservation(r); setShowReservationModal(true); setMobileSidebarOpen(null) } : undefined} />
-                      : <PlacesSidebar tripId={tripId} places={places} categories={categories} assignments={assignments} selectedDayId={selectedDayId} selectedPlaceId={selectedPlaceId} onPlaceClick={(placeId) => { handlePlaceClick(placeId); setMobileSidebarOpen(null) }} onAddPlace={() => { setEditingPlace(null); setShowPlaceForm(true); setMobileSidebarOpen(null) }} onAssignToDay={handleAssignToDay} onEditPlace={(place) => { setEditingPlace(place); setEditingAssignmentId(null); setShowPlaceForm(true); setMobileSidebarOpen(null) }} onDeletePlace={(placeId) => handleDeletePlace(placeId)} onBulkDeletePlaces={(ids) => setDeletePlaceIds(ids)} onBulkDeleteConfirm={(ids) => confirmDeletePlaces(ids)} days={days} isMobile onCategoryFilterChange={setMapCategoryFilter} onPlacesFilterChange={setMapPlacesFilter} pushUndo={pushUndo} />
+                      ? <DayPlanSidebar tripId={tripId} trip={trip} days={days} places={places} categories={categories} assignments={assignments} selectedDayId={selectedDayId} selectedPlaceId={selectedPlaceId} selectedAssignmentId={selectedAssignmentId} onSelectDay={(id) => { handleSelectDay(id); setMobileSidebarOpen(null) }} onPlaceClick={(placeId, assignmentId) => { handlePlaceClick(placeId, assignmentId) }} onReorder={handleReorder} onUpdateDayTitle={handleUpdateDayTitle} onAssignToDay={handleAssignToDay} onRouteCalculated={(r) => { if (r) { setRoute(r.coordinates); setRouteInfo({ distance: r.distanceText, duration: r.durationText }) } }} reservations={reservations} visibleConnectionIds={visibleConnections} onToggleConnection={toggleConnection} onAddReservation={(dayId) => { setEditingReservation(null); tripActions.setSelectedDay(dayId); setShowReservationModal(true); setMobileSidebarOpen(null) }} onAddPlace={() => { setEditingPlace(null); setShowPlaceForm(true); setMobileSidebarOpen(null) }} onDayDetail={(day) => { setShowDayDetail(day); setSelectedPlaceId(null); selectAssignment(null); setMobileSidebarOpen(null) }} accommodations={tripAccommodations} onNavigateToFiles={() => { setMobileSidebarOpen(null); handleTabChange('dateien') }} onExpandedDaysChange={setExpandedDayIds} pushUndo={pushUndo} canUndo={canUndo} lastActionLabel={lastActionLabel} onUndo={handleUndo} onEditTransport={can('day_edit', trip) ? (reservation) => { setEditingTransport(reservation); setTransportModalDayId(reservation.day_id ?? null); setShowTransportModal(true); setMobileSidebarOpen(null) } : undefined} onEditReservation={can('reservation_edit', trip) ? (r) => { setEditingReservation(r); setShowReservationModal(true); setMobileSidebarOpen(null) } : undefined} initialScrollTop={mobilePlanScrollTopRef.current} onScrollTopChange={(top) => { mobilePlanScrollTopRef.current = top }} />
+                      : <PlacesSidebar tripId={tripId} places={places} categories={categories} assignments={assignments} selectedDayId={selectedDayId} selectedPlaceId={selectedPlaceId} onPlaceClick={(placeId) => { handlePlaceClick(placeId); setMobileSidebarOpen(null) }} onAddPlace={() => { setEditingPlace(null); setShowPlaceForm(true); setMobileSidebarOpen(null) }} onAssignToDay={handleAssignToDay} onEditPlace={(place) => { setEditingPlace(place); setEditingAssignmentId(null); setShowPlaceForm(true); setMobileSidebarOpen(null) }} onDeletePlace={(placeId) => handleDeletePlace(placeId)} onBulkDeletePlaces={(ids) => setDeletePlaceIds(ids)} onBulkDeleteConfirm={(ids) => confirmDeletePlaces(ids)} days={days} isMobile onCategoryFilterChange={setMapCategoryFilter} onPlacesFilterChange={setMapPlacesFilter} pushUndo={pushUndo} initialScrollTop={mobilePlacesScrollTopRef.current} onScrollTopChange={(top) => { mobilePlacesScrollTopRef.current = top }} />
                     }
                   </div>
                 </div>