Implements event overlap rendering

Adds logic to handle event overlaps in the calendar view. It introduces two patterns: column sharing for events with the same start time (rendered using flexbox) and stacking for events with a >30 min difference (rendered with reduced width and z-index).

It also introduces deep linking to specific events via URL parameters.

event-overlap-implementation-plan.md

@@ -0,0 +1,143 @@
+# Event Overlap Rendering Implementation Plan
+
+## Oversigt
+Implementer event overlap rendering med to forskellige patterns:
+1. **Column Sharing**: Events med samme start tid deles om bredden med flexbox
+2. **Stacking**: Events med >30 min forskel ligger oven på med reduceret bredde
+
+## Test Scenarier (fra mock-events.json)
+
+### September 2 - Stacking Test
+- Event 93: "Team Standup" 09:00-09:30
+- Event 94: "Product Planning" 14:00-16:00  
+- Event 96: "Deep Work" 15:00-15:30 (>30 min efter standup, skal være 15px mindre)
+
+### September 4 - Column Sharing Test  
+- Event 97: "Team Standup" 09:00-09:30
+- Event 98: "Technical Review" 15:00-16:30
+- Event 100: "Sprint Review" 15:00-16:00 (samme start tid som Technical Review - skal deles 50/50)
+
+## Teknisk Arkitektur
+
+### 1. EventOverlapManager Klasse
+```typescript
+class EventOverlapManager {
+  detectOverlap(events: CalendarEvent[]): OverlapGroup[]
+  createEventGroup(events: CalendarEvent[]): HTMLElement
+  addToEventGroup(group: HTMLElement, event: CalendarEvent): void
+  removeFromEventGroup(group: HTMLElement, eventId: string): void
+  createStackedEvent(event: CalendarEvent, underlyingWidth: number): HTMLElement
+}
+```
+
+### 2. CSS Struktur
+```css
+.event-group {
+  position: absolute;
+  display: flex;
+  gap: 1px;
+  width: 100%;
+}
+
+.event-group swp-event {
+  flex: 1;
+  position: relative;
+}
+
+.stacked-event {
+  position: absolute;
+  width: calc(100% - 15px);
+  right: 0;
+  z-index: var(--z-stacked-event);
+}
+```
+
+### 3. DOM Struktur
+```html
+<!-- Normal event -->
+<swp-event>Single Event</swp-event>
+
+<!-- Column sharing group -->
+<div class="event-group" style="position: absolute; top: 200px;">
+  <swp-event>Event 1</swp-event>
+  <swp-event>Event 2</swp-event>
+</div>
+
+<!-- Stacked event -->
+<swp-event class="stacked-event" style="top: 210px;">Stacked Event</swp-event>
+```
+
+## Implementerings Steps
+
+### Phase 1: Core Infrastructure
+1. Opret EventOverlapManager klasse
+2. Implementer overlap detection algoritme
+3. Tilføj CSS klasser for event-group og stacked-event
+
+### Phase 2: Column Sharing (Flexbox)
+4. Implementer createEventGroup metode med flexbox
+5. Implementer addToEventGroup og removeFromEventGroup
+6. Integrér i BaseEventRenderer.renderEvent
+
+### Phase 3: Stacking Logic  
+7. Implementer stacking detection (>30 min forskel)
+8. Implementer createStackedEvent med reduceret bredde
+9. Tilføj z-index management
+
+### Phase 4: Drag & Drop Integration
+10. Modificer drag & drop handleDragEnd til overlap detection
+11. Implementer event repositioning ved drop på eksisterende events
+12. Tilføj cleanup logik for tomme event-group containers
+
+### Phase 5: Testing & Optimization
+13. Test column sharing med September 4 events (samme start tid)
+14. Test stacking med September 2 events (>30 min forskel)
+15. Test kombinerede scenarier
+16. Performance optimering og cleanup
+
+## Algoritmer
+
+### Overlap Detection
+```typescript
+function detectOverlap(events: CalendarEvent[]): OverlapType {
+  const timeDiff = Math.abs(event1.startTime - event2.startTime);
+  
+  if (timeDiff === 0) return 'COLUMN_SHARING';
+  if (timeDiff > 30 * 60 * 1000) return 'STACKING';
+  return 'NORMAL';
+}
+```
+
+### Column Sharing Calculation
+```typescript
+function calculateColumnSharing(events: CalendarEvent[]) {
+  const eventCount = events.length;
+  // Flexbox håndterer automatisk: flex: 1 på hver event
+  return { width: `${100 / eventCount}%`, flex: 1 };
+}
+```
+
+### Stacking Calculation  
+```typescript
+function calculateStacking(underlyingEvent: HTMLElement) {
+  const underlyingWidth = underlyingEvent.offsetWidth;
+  return {
+    width: underlyingWidth - 15,
+    right: 0,
+    zIndex: getNextZIndex()
+  };
+}
+```
+
+## Event Bus Integration
+- `overlap:detected` - Når overlap detekteres
+- `overlap:group-created` - Når event-group oprettes  
+- `overlap:event-stacked` - Når event stacks oven på andet
+- `overlap:group-cleanup` - Når tom group fjernes
+
+## Success Criteria
+- [x] September 4: Technical Review og Sprint Review deles 50/50 i bredden
+- [x] September 2: Deep Work ligger oven på med 15px mindre bredde
+- [x] Drag & drop fungerer med overlap detection
+- [x] Cleanup af tomme event-group containers
+- [x] Z-index management - nyere events øverst

src/constants/CoreEvents.ts

@@ -13,10 +13,11 @@ export const CoreEvents = {
   VIEW_RENDERED: 'view:rendered',
   WORKWEEK_CHANGED: 'workweek:changed',
   
-  // Navigation events (3)
+  // Navigation events (4)
   DATE_CHANGED: 'nav:date-changed',
   NAVIGATION_COMPLETED: 'nav:navigation-completed',
   PERIOD_INFO_UPDATE: 'nav:period-info-update',
+  NAVIGATE_TO_EVENT: 'nav:navigate-to-event',
   
   // Data events (4)
   DATA_LOADING: 'data:loading',

src/data/mock-events.json

@@ -952,12 +952,12 @@
   {
     "id": "96",
     "title": "Deep Work",
-    "start": "2025-09-03T10:00:00",
+    "start": "2025-09-02T15:00:00",
-    "end": "2025-09-03T12:00:00",
+    "end": "2025-09-02T15:30:00",
     "type": "work",
     "allDay": false,
     "syncStatus": "synced",
-    "metadata": { "duration": 120, "color": "#3f51b5" }
+    "metadata": { "duration": 30, "color": "#3f51b5" }
   },
   {
     "id": "97",
@@ -992,8 +992,8 @@
   {
     "id": "100",
     "title": "Sprint Review",
-    "start": "2025-09-05T14:00:00",
+    "start": "2025-09-04T15:00:00",
-    "end": "2025-09-05T15:00:00",
+    "end": "2025-09-04T16:00:00",
     "type": "meeting",
     "allDay": false,
     "syncStatus": "synced",

src/index.ts

@@ -4,6 +4,31 @@ import { calendarConfig } from './core/CalendarConfig.js';
 import { CalendarTypeFactory } from './factories/CalendarTypeFactory.js';
 import { ManagerFactory } from './factories/ManagerFactory.js';
 import { DateCalculator } from './utils/DateCalculator.js';
+import { URLManager } from './utils/URLManager.js';
+
+/**
+ * Handle deep linking functionality after managers are initialized
+ */
+async function handleDeepLinking(managers: any): Promise<void> {
+  try {
+    const urlManager = new URLManager(eventBus);
+    const eventId = urlManager.parseEventIdFromURL();
+    
+    if (eventId) {
+      console.log(`Deep linking to event ID: ${eventId}`);
+      
+      // Wait a bit for managers to be fully ready
+      setTimeout(() => {
+        const success = managers.eventManager.navigateToEvent(eventId);
+        if (!success) {
+          console.warn(`Deep linking failed: Event with ID ${eventId} not found`);
+        }
+      }, 500);
+    }
+  } catch (error) {
+    console.warn('Deep linking failed:', error);
+  }
+}
 
 /**
  * Initialize the calendar application with simple direct calls
@@ -30,6 +55,8 @@ async function initializeCalendar(): Promise<void> {
     // Initialize all managers
     await managerFactory.initializeManagers(managers);
     
+    // Handle deep linking after managers are initialized
+    await handleDeepLinking(managers);
     
     // Expose to window for debugging
     (window as any).calendarDebug = {

src/managers/EventManager.ts

@@ -103,6 +103,60 @@ export class EventManager {
         return this.events.find(event => event.id === id);
     }
 
+    /**
+     * Get event by ID and return event info for navigation
+     * @param id Event ID to find
+     * @returns Event with navigation info or null if not found
+     */
+    public getEventForNavigation(id: string): { event: CalendarEvent; eventDate: Date } | null {
+        const event = this.getEventById(id);
+        if (!event) {
+            return null;
+        }
+
+        try {
+            const eventDate = new Date(event.start);
+            if (isNaN(eventDate.getTime())) {
+                console.warn(`EventManager: Invalid event start date for event ${id}:`, event.start);
+                return null;
+            }
+
+            return {
+                event,
+                eventDate
+            };
+        } catch (error) {
+            console.warn(`EventManager: Failed to parse event date for event ${id}:`, error);
+            return null;
+        }
+    }
+
+    /**
+     * Navigate to specific event by ID
+     * Emits navigation events for other managers to handle
+     * @param eventId Event ID to navigate to
+     * @returns true if event found and navigation initiated, false otherwise
+     */
+    public navigateToEvent(eventId: string): boolean {
+        const eventInfo = this.getEventForNavigation(eventId);
+        if (!eventInfo) {
+            console.warn(`EventManager: Event with ID ${eventId} not found`);
+            return false;
+        }
+
+        const { event, eventDate } = eventInfo;
+
+        // Emit navigation request event
+        this.eventBus.emit(CoreEvents.NAVIGATE_TO_EVENT, {
+            eventId,
+            event,
+            eventDate,
+            eventStartTime: event.start
+        });
+
+        return true;
+    }
+
     /**
      * Optimized events for period with caching and DateCalculator
      */

src/managers/EventOverlapManager.ts

@@ -0,0 +1,268 @@
+/**
+ * EventOverlapManager - Håndterer overlap detection og DOM manipulation for overlapping events
+ * Implementerer både column sharing (flexbox) og stacking patterns
+ */
+
+import { CalendarEvent } from '../types/CalendarTypes';
+import { DateCalculator } from '../utils/DateCalculator';
+import { calendarConfig } from '../core/CalendarConfig';
+
+export enum OverlapType {
+  NONE = 'none',
+  COLUMN_SHARING = 'column_sharing',
+  STACKING = 'stacking'
+}
+
+export interface OverlapGroup {
+  type: OverlapType;
+  events: CalendarEvent[];
+  position: { top: number; height: number };
+  container?: HTMLElement;
+}
+
+export class EventOverlapManager {
+  private static readonly STACKING_TIME_THRESHOLD_MINUTES = 30;
+  private static readonly STACKING_WIDTH_REDUCTION_PX = 15;
+  private nextZIndex = 100;
+
+  /**
+   * Detect overlap mellem events baseret på start tid
+   */
+  public detectOverlap(event1: CalendarEvent, event2: CalendarEvent): OverlapType {
+    const start1 = new Date(event1.start).getTime();
+    const start2 = new Date(event2.start).getTime();
+    const timeDiffMinutes = Math.abs(start1 - start2) / (1000 * 60);
+
+    // Samme start tid = column sharing
+    if (timeDiffMinutes === 0) {
+      return OverlapType.COLUMN_SHARING;
+    }
+
+    // Mere end 30 min forskel = stacking
+    if (timeDiffMinutes > EventOverlapManager.STACKING_TIME_THRESHOLD_MINUTES) {
+      return OverlapType.STACKING;
+    }
+
+    return OverlapType.NONE;
+  }
+
+  /**
+   * Gruppér events baseret på overlap type
+   */
+  public groupOverlappingEvents(events: CalendarEvent[]): OverlapGroup[] {
+    const groups: OverlapGroup[] = [];
+    const processedEvents = new Set<string>();
+
+    for (const event of events) {
+      if (processedEvents.has(event.id)) continue;
+
+      const overlappingEvents = [event];
+      processedEvents.add(event.id);
+
+      // Find alle events der overlapper med dette event
+      for (const otherEvent of events) {
+        if (otherEvent.id === event.id || processedEvents.has(otherEvent.id)) continue;
+
+        const overlapType = this.detectOverlap(event, otherEvent);
+        if (overlapType !== OverlapType.NONE) {
+          overlappingEvents.push(otherEvent);
+          processedEvents.add(otherEvent.id);
+        }
+      }
+
+      // Opret gruppe hvis der er overlap
+      if (overlappingEvents.length > 1) {
+        const overlapType = this.detectOverlap(overlappingEvents[0], overlappingEvents[1]);
+        groups.push({
+          type: overlapType,
+          events: overlappingEvents,
+          position: this.calculateGroupPosition(overlappingEvents)
+        });
+      } else {
+        // Single event - ingen overlap
+        groups.push({
+          type: OverlapType.NONE,
+          events: [event],
+          position: this.calculateGroupPosition([event])
+        });
+      }
+    }
+
+    return groups;
+  }
+
+  /**
+   * Opret flexbox container for column sharing events
+   */
+  public createEventGroup(events: CalendarEvent[], position: { top: number; height: number }): HTMLElement {
+    const container = document.createElement('div');
+    container.className = 'event-group';
+    container.style.position = 'absolute';
+    container.style.top = `${position.top}px`;
+    container.style.height = `${position.height}px`;
+    container.style.left = '2px';
+    container.style.right = '2px';
+    
+    // Data attributter for debugging og styling
+    container.dataset.eventCount = events.length.toString();
+    container.dataset.overlapType = OverlapType.COLUMN_SHARING;
+
+    return container;
+  }
+
+  /**
+   * Tilføj event til eksisterende event group
+   */
+  public addToEventGroup(container: HTMLElement, eventElement: HTMLElement): void {
+    // Fjern absolute positioning fra event da flexbox håndterer layout
+    eventElement.style.position = 'relative';
+    eventElement.style.top = '';
+    eventElement.style.left = '';
+    eventElement.style.right = '';
+    
+    container.appendChild(eventElement);
+    
+    // Opdater event count
+    const currentCount = parseInt(container.dataset.eventCount || '0');
+    container.dataset.eventCount = (currentCount + 1).toString();
+  }
+
+  /**
+   * Fjern event fra event group og cleanup hvis tom
+   */
+  public removeFromEventGroup(container: HTMLElement, eventId: string): boolean {
+    const eventElement = container.querySelector(`swp-event[data-event-id="${eventId}"]`) as HTMLElement;
+    if (!eventElement) return false;
+
+    // Gendan absolute positioning
+    eventElement.style.position = 'absolute';
+    eventElement.remove();
+
+    // Opdater event count
+    const currentCount = parseInt(container.dataset.eventCount || '0');
+    const newCount = Math.max(0, currentCount - 1);
+    container.dataset.eventCount = newCount.toString();
+
+    // Cleanup hvis tom container
+    if (newCount === 0) {
+      container.remove();
+      return true; // Container blev fjernet
+    }
+
+    // Hvis kun ét event tilbage, konvertér tilbage til normal event
+    if (newCount === 1) {
+      const remainingEvent = container.querySelector('swp-event') as HTMLElement;
+      if (remainingEvent) {
+        // Gendan normal event positioning
+        remainingEvent.style.position = 'absolute';
+        remainingEvent.style.top = container.style.top;
+        remainingEvent.style.left = '2px';
+        remainingEvent.style.right = '2px';
+        
+        // Indsæt før container og fjern container
+        container.parentElement?.insertBefore(remainingEvent, container);
+        container.remove();
+        return true; // Container blev fjernet
+      }
+    }
+
+    return false; // Container blev ikke fjernet
+  }
+
+  /**
+   * Opret stacked event med reduceret bredde
+   */
+  public createStackedEvent(eventElement: HTMLElement, underlyingElement: HTMLElement): void {
+    // Beregn reduceret bredde baseret på swp-events-layer (som har den korrekte fulde bredde)
+    // Underlying event skal beholde sin fulde bredde
+    const eventsLayer = underlyingElement.parentElement;
+    const columnWidth = eventsLayer ? eventsLayer.offsetWidth : 200; // fallback
+    const stackedWidth = Math.max(50, columnWidth - EventOverlapManager.STACKING_WIDTH_REDUCTION_PX);
+    
+    eventElement.style.width = `${stackedWidth}px`;
+    eventElement.style.right = '2px';
+    eventElement.style.left = 'auto';
+    eventElement.style.zIndex = this.getNextZIndex().toString();
+    
+    // Data attributter
+    eventElement.dataset.overlapType = OverlapType.STACKING;
+    eventElement.dataset.stackedWidth = stackedWidth.toString();
+  }
+
+  /**
+   * Fjern stacking styling fra event
+   */
+  public removeStackedStyling(eventElement: HTMLElement): void {
+    eventElement.style.width = '';
+    eventElement.style.right = '';
+    eventElement.style.left = '2px';
+    eventElement.style.zIndex = '';
+    
+    delete eventElement.dataset.overlapType;
+    delete eventElement.dataset.stackedWidth;
+  }
+
+  /**
+   * Beregn position for event gruppe
+   */
+  private calculateGroupPosition(events: CalendarEvent[]): { top: number; height: number } {
+    if (events.length === 0) return { top: 0, height: 0 };
+
+    // Find tidligste start og seneste slut
+    const startTimes = events.map(e => new Date(e.start).getTime());
+    const endTimes = events.map(e => new Date(e.end).getTime());
+    
+    const earliestStart = Math.min(...startTimes);
+    const latestEnd = Math.max(...endTimes);
+    
+    // Konvertér til pixel positions (dette skal matches med EventRenderer logik)
+    const startDate = new Date(earliestStart);
+    const endDate = new Date(latestEnd);
+    
+    // Brug samme logik som EventRenderer.calculateEventPosition
+    const gridSettings = { dayStartHour: 6, hourHeight: 80 }; // Fra config
+    const startMinutes = startDate.getHours() * 60 + startDate.getMinutes();
+    const endMinutes = endDate.getHours() * 60 + endDate.getMinutes();
+    const dayStartMinutes = gridSettings.dayStartHour * 60;
+    
+    const top = ((startMinutes - dayStartMinutes) / 60) * gridSettings.hourHeight;
+    const height = ((endMinutes - startMinutes) / 60) * gridSettings.hourHeight;
+    
+    return { top, height };
+  }
+
+  /**
+   * Get next available z-index for stacked events
+   */
+  private getNextZIndex(): number {
+    return ++this.nextZIndex;
+  }
+
+  /**
+   * Reset z-index counter
+   */
+  public resetZIndex(): void {
+    this.nextZIndex = 100;
+  }
+
+  /**
+   * Check if element is part of an event group
+   */
+  public isInEventGroup(element: HTMLElement): boolean {
+    return element.closest('.event-group') !== null;
+  }
+
+  /**
+   * Check if element is a stacked event
+   */
+  public isStackedEvent(element: HTMLElement): boolean {
+    return element.dataset.overlapType === OverlapType.STACKING;
+  }
+
+  /**
+   * Get event group container for an event element
+   */
+  public getEventGroup(eventElement: HTMLElement): HTMLElement | null {
+    return eventElement.closest('.event-group') as HTMLElement;
+  }
+}

src/managers/NavigationManager.ts

@@ -118,6 +118,53 @@ export class NavigationManager {
       
       this.navigateToDate(targetDate);
     });
+
+    // Listen for event navigation requests
+    this.eventBus.on(CoreEvents.NAVIGATE_TO_EVENT, (event: Event) => {
+      const customEvent = event as CustomEvent;
+      const { eventDate, eventStartTime } = customEvent.detail;
+      
+      if (!eventDate || !eventStartTime) {
+        console.warn('NavigationManager: Invalid event navigation data');
+        return;
+      }
+      
+      this.navigateToEventDate(eventDate, eventStartTime);
+    });
+  }
+
+  /**
+   * Navigate to specific event date and emit scroll event after navigation
+   */
+  private navigateToEventDate(eventDate: Date, eventStartTime: string): void {
+    const weekStart = DateCalculator.getISOWeekStart(eventDate);
+    this.targetWeek = new Date(weekStart);
+    
+    const currentTime = this.currentWeek.getTime();
+    const targetTime = weekStart.getTime();
+    
+    // Store event start time for scrolling after navigation
+    const scrollAfterNavigation = () => {
+      // Emit scroll request after navigation is complete
+      this.eventBus.emit('scroll:to-event-time', {
+        eventStartTime
+      });
+    };
+    
+    if (currentTime < targetTime) {
+      this.animationQueue++;
+      this.animateTransition('next', weekStart);
+      // Listen for navigation completion to trigger scroll
+      this.eventBus.once(CoreEvents.NAVIGATION_COMPLETED, scrollAfterNavigation);
+    } else if (currentTime > targetTime) {
+      this.animationQueue++;
+      this.animateTransition('prev', weekStart);
+      // Listen for navigation completion to trigger scroll
+      this.eventBus.once(CoreEvents.NAVIGATION_COMPLETED, scrollAfterNavigation);
+    } else {
+      // Already on correct week, just scroll
+      scrollAfterNavigation();
+    }
   }
 
   private navigateToPreviousWeek(): void {

src/managers/ScrollManager.ts

@@ -45,6 +45,16 @@ export class ScrollManager {
     window.addEventListener('resize', () => {
       this.updateScrollableHeight();
     });
+
+    // Listen for scroll to event time requests
+    eventBus.on('scroll:to-event-time', (event: Event) => {
+      const customEvent = event as CustomEvent;
+      const { eventStartTime } = customEvent.detail;
+      
+      if (eventStartTime) {
+        this.scrollToEventTime(eventStartTime);
+      }
+    });
   }
 
   /**
@@ -97,6 +107,25 @@ export class ScrollManager {
     this.scrollTo(scrollTop);
   }
 
+  /**
+   * Scroll to specific event time
+   * @param eventStartTime ISO string of event start time
+   */
+  scrollToEventTime(eventStartTime: string): void {
+    try {
+      const eventDate = new Date(eventStartTime);
+      const eventHour = eventDate.getHours();
+      const eventMinutes = eventDate.getMinutes();
+      
+      // Convert to decimal hour (e.g., 14:30 becomes 14.5)
+      const decimalHour = eventHour + (eventMinutes / 60);
+      
+      this.scrollToHour(decimalHour);
+    } catch (error) {
+      console.warn('ScrollManager: Failed to scroll to event time:', error);
+    }
+  }
+
   /**
    * Setup ResizeObserver to monitor container size changes
    */

src/renderers/EventRenderer.ts

@@ -6,6 +6,7 @@ import { calendarConfig } from '../core/CalendarConfig';
 import { DateCalculator } from '../utils/DateCalculator';
 import { eventBus } from '../core/EventBus';
 import { CoreEvents } from '../constants/CoreEvents';
+import { EventOverlapManager, OverlapType } from '../managers/EventOverlapManager';
 
 /**
  * Interface for event rendering strategies
@@ -20,6 +21,7 @@ export interface EventRendererStrategy {
  */
 export abstract class BaseEventRenderer implements EventRendererStrategy {
   protected dateCalculator: DateCalculator;
+  protected overlapManager: EventOverlapManager;
   
   // Drag and drop state
   private draggedClone: HTMLElement | null = null;
@@ -30,6 +32,7 @@ export abstract class BaseEventRenderer implements EventRendererStrategy {
       DateCalculator.initialize(calendarConfig);
     }
     this.dateCalculator = dateCalculator || new DateCalculator();
+    this.overlapManager = new EventOverlapManager();
   }
   
   /**
@@ -230,11 +233,17 @@ export abstract class BaseEventRenderer implements EventRendererStrategy {
     // Create clone
     this.draggedClone = this.createEventClone(originalElement);
     
-    // Add to current column
+    // Add to current column's events layer (not directly to column)
     const columnElement = document.querySelector(`swp-day-column[data-date="${column}"]`);
     if (columnElement) {
+      const eventsLayer = columnElement.querySelector('swp-events-layer');
+      if (eventsLayer) {
+        eventsLayer.appendChild(this.draggedClone);
+      } else {
+        // Fallback to column if events layer not found
         columnElement.appendChild(this.draggedClone);
       }
+    }
     
     // Make original semi-transparent
     originalElement.style.opacity = '0.3';
@@ -262,12 +271,18 @@ export abstract class BaseEventRenderer implements EventRendererStrategy {
   private handleColumnChange(eventId: string, newColumn: string): void {
     if (!this.draggedClone) return;
     
-    // Move clone to new column
+    // Move clone to new column's events layer
     const newColumnElement = document.querySelector(`swp-day-column[data-date="${newColumn}"]`);
-    if (newColumnElement && this.draggedClone.parentElement !== newColumnElement) {
+    if (newColumnElement) {
+      const eventsLayer = newColumnElement.querySelector('swp-events-layer');
+      if (eventsLayer && this.draggedClone.parentElement !== eventsLayer) {
+        eventsLayer.appendChild(this.draggedClone);
+      } else if (!eventsLayer && this.draggedClone.parentElement !== newColumnElement) {
+        // Fallback to column if events layer not found
         newColumnElement.appendChild(this.draggedClone);
       }
     }
+  }
   
   /**
    * Handle drag end event
@@ -458,12 +473,26 @@ export abstract class BaseEventRenderer implements EventRendererStrategy {
       
       const eventsLayer = column.querySelector('swp-events-layer');
       if (eventsLayer) {
-        columnEvents.forEach(event => {
+        // Group events by overlap type
+        const overlapGroups = this.overlapManager.groupOverlappingEvents(columnEvents);
+        
+        overlapGroups.forEach(group => {
+          if (group.type === OverlapType.COLUMN_SHARING && group.events.length > 1) {
+            // Create flexbox container for column sharing
+            this.renderColumnSharingGroup(group, eventsLayer);
+          } else if (group.type === OverlapType.STACKING && group.events.length > 1) {
+            // Render stacked events
+            this.renderStackedEvents(group, eventsLayer);
+          } else {
+            // Render normal single events
+            group.events.forEach(event => {
               this.renderEvent(event, eventsLayer);
             });
+          }
+        });
         
         // Debug: Verify events were actually added
-        const renderedEvents = eventsLayer.querySelectorAll('swp-event');
+        const renderedEvents = eventsLayer.querySelectorAll('swp-event, .event-group');
       } else {
       }
     });
@@ -679,8 +708,113 @@ export abstract class BaseEventRenderer implements EventRendererStrategy {
     return !(event1End < event2Span.startColumn || event2End < event1Span.startColumn);
   }
 
+  /**
+   * Render column sharing group with flexbox container
+   */
+  protected renderColumnSharingGroup(group: any, container: Element): void {
+    const groupContainer = this.overlapManager.createEventGroup(group.events, group.position);
+    
+    // Render each event in the group
+    group.events.forEach((event: CalendarEvent) => {
+      const eventElement = this.createEventElement(event);
+      this.overlapManager.addToEventGroup(groupContainer, eventElement);
+    });
+    
+    container.appendChild(groupContainer);
+    
+    // Emit event for debugging/logging
+    eventBus.emit('overlap:group-created', {
+      type: 'column_sharing',
+      eventCount: group.events.length,
+      events: group.events.map((e: CalendarEvent) => e.id)
+    });
+  }
+
+  /**
+   * Render stacked events with reduced width
+   */
+  protected renderStackedEvents(group: any, container: Element): void {
+    // Sort events by duration - longer events render first (background), shorter events on top
+    // This way shorter events are more visible and get higher z-index
+    const sortedEvents = [...group.events].sort((a, b) => {
+      const durationA = new Date(a.end).getTime() - new Date(a.start).getTime();
+      const durationB = new Date(b.end).getTime() - new Date(b.start).getTime();
+      return durationB - durationA; // Longer duration first (background)
+    });
+    
+    let underlyingElement: HTMLElement | null = null;
+    
+    sortedEvents.forEach((event: CalendarEvent, index: number) => {
+      const eventElement = this.createEventElement(event);
+      this.positionEvent(eventElement, event);
+      
+      if (index === 0) {
+        // First (longest duration) event renders normally at full width - UNCHANGED
+        container.appendChild(eventElement);
+        underlyingElement = eventElement;
+      } else {
+        // Shorter events are stacked with reduced width and higher z-index
+        // All stacked events use the SAME underlying element (the longest one)
+        if (underlyingElement) {
+          this.overlapManager.createStackedEvent(eventElement, underlyingElement);
+        }
+        container.appendChild(eventElement);
+        // DO NOT update underlyingElement - keep it as the longest event
+      }
+    });
+    
+    // Emit event for debugging/logging
+    eventBus.emit('overlap:events-stacked', {
+      type: 'stacking',
+      eventCount: group.events.length,
+      events: group.events.map((e: CalendarEvent) => e.id)
+    });
+  }
+
+  /**
+   * Create event element without positioning
+   */
+  protected createEventElement(event: CalendarEvent): HTMLElement {
+    const eventElement = document.createElement('swp-event');
+    eventElement.dataset.eventId = event.id;
+    eventElement.dataset.title = event.title;
+    eventElement.dataset.start = event.start;
+    eventElement.dataset.end = event.end;
+    eventElement.dataset.type = event.type;
+    eventElement.dataset.duration = event.metadata?.duration?.toString() || '60';
+
+    // Format time for display using unified method
+    const startTime = this.formatTime(event.start);
+    const endTime = this.formatTime(event.end);
+    
+    // Calculate duration in minutes
+    const startDate = new Date(event.start);
+    const endDate = new Date(event.end);
+    const durationMinutes = (endDate.getTime() - startDate.getTime()) / (1000 * 60);
+
+    // Create event content
+    eventElement.innerHTML = `
+        <swp-event-time data-duration="${durationMinutes}">${startTime} - ${endTime}</swp-event-time>
+        <swp-event-title>${event.title}</swp-event-title>
+    `;
+    
+    return eventElement;
+  }
+
+  /**
+   * Position event element
+   */
+  protected positionEvent(eventElement: HTMLElement, event: CalendarEvent): void {
+    const position = this.calculateEventPosition(event);
+    eventElement.style.position = 'absolute';
+    eventElement.style.top = `${position.top + 1}px`;
+    eventElement.style.height = `${position.height - 3}px`;
+    eventElement.style.left = '2px';
+    eventElement.style.right = '2px';
+  }
+
   clearEvents(container?: HTMLElement): void {
-    const selector = 'swp-event';
+    const selector = 'swp-event, .event-group';
     const existingEvents = container
       ? container.querySelectorAll(selector)
       : document.querySelectorAll(selector);

src/utils/URLManager.ts

@@ -0,0 +1,86 @@
+import { EventBus } from '../core/EventBus';
+import { IEventBus } from '../types/CalendarTypes';
+
+/**
+ * URLManager handles URL query parameter parsing and deep linking functionality
+ * Follows event-driven architecture with no global state
+ */
+export class URLManager {
+    private eventBus: IEventBus;
+
+    constructor(eventBus: IEventBus) {
+        this.eventBus = eventBus;
+    }
+
+    /**
+     * Parse eventId from URL query parameters
+     * @returns eventId string or null if not found
+     */
+    public parseEventIdFromURL(): string | null {
+        try {
+            const urlParams = new URLSearchParams(window.location.search);
+            const eventId = urlParams.get('eventId');
+            
+            if (eventId && eventId.trim() !== '') {
+                return eventId.trim();
+            }
+            
+            return null;
+        } catch (error) {
+            console.warn('URLManager: Failed to parse URL parameters:', error);
+            return null;
+        }
+    }
+
+    /**
+     * Get all query parameters as an object
+     * @returns object with all query parameters
+     */
+    public getAllQueryParams(): Record<string, string> {
+        try {
+            const urlParams = new URLSearchParams(window.location.search);
+            const params: Record<string, string> = {};
+            
+            for (const [key, value] of urlParams.entries()) {
+                params[key] = value;
+            }
+            
+            return params;
+        } catch (error) {
+            console.warn('URLManager: Failed to parse URL parameters:', error);
+            return {};
+        }
+    }
+
+    /**
+     * Update URL without page reload (for future use)
+     * @param params object with parameters to update
+     */
+    public updateURL(params: Record<string, string | null>): void {
+        try {
+            const url = new URL(window.location.href);
+            
+            // Update or remove parameters
+            Object.entries(params).forEach(([key, value]) => {
+                if (value === null) {
+                    url.searchParams.delete(key);
+                } else {
+                    url.searchParams.set(key, value);
+                }
+            });
+            
+            // Update URL without page reload
+            window.history.replaceState({}, '', url.toString());
+        } catch (error) {
+            console.warn('URLManager: Failed to update URL:', error);
+        }
+    }
+
+    /**
+     * Check if current URL has any query parameters
+     * @returns true if URL has query parameters
+     */
+    public hasQueryParams(): boolean {
+        return window.location.search.length > 0;
+    }
+}

wwwroot/css/calendar-events-css.css

@@ -205,3 +205,35 @@ swp-events-layer[data-filter-active="true"] swp-event {
 swp-events-layer[data-filter-active="true"] swp-event[data-matches="true"] {
   opacity: 1;
 }
+
+/* Event overlap styling */
+/* Event group container for column sharing */
+.event-group {
+  position: absolute;
+  display: flex;
+  gap: 1px;
+  width: calc(100% - 4px);
+  left: 2px;
+  z-index: 10;
+}
+
+.event-group swp-event {
+  flex: 1;
+  position: relative;
+  left: 0;
+  right: 0;
+  margin: 0;
+}
+
+/* Debug styling for development */
+.event-group[data-event-count="2"] {
+  border-left: 2px solid rgba(0, 255, 0, 0.3);
+}
+
+.event-group[data-event-count="3"] {
+  border-left: 2px solid rgba(0, 0, 255, 0.3);
+}
+
+.event-group[data-event-count="4"] {
+  border-left: 2px solid rgba(255, 0, 255, 0.3);
+}