Refactor calendar datasource architecture

Centralizes date calculation logic into DateColumnDataSource
Improves separation of concerns across rendering components

Key changes:
- Introduces IColumnInfo interface for flexible column data
- Moves date calculation from multiple managers to dedicated datasource
- Removes duplicate date rendering logic
- Prepares architecture for future resource-based views

.claude/settings.local.json

@@ -0,0 +1,9 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(npm run build:*)"
+    ],
+    "deny": [],
+    "ask": []
+  }
+}

coding-sessions/2025-11-13-datasource-architecture-implementation.md

@@ -0,0 +1,769 @@
+# DataSource Architecture Implementation
+
+**Date:** November 13, 2025
+**Type:** Architecture refactoring, Data flow optimization
+**Status:** ✅ Complete (with course corrections)
+**Main Goal:** Implement DataSource pattern to centralize date calculation and prepare for dual-mode calendar (date-based vs resource-based)
+
+---
+
+## Executive Summary
+
+Successfully implemented DataSource architecture to centralize date calculations and clean up rendering responsibilities. Initial implementation had architectural violations that were corrected through user guidance.
+
+**Key Outcomes:**
+- ✅ DateColumnDataSource created as single source of truth for dates
+- ✅ GridRenderer responsibility corrected (structure only, not event rendering)
+- ✅ ColumnRenderer receives dates instead of calculating them
+- ✅ Navigation flow fixed (no duplicate rendering)
+- ✅ Clean separation of concerns restored
+- ⚠️ Initial conversation compaction caused architectural mistakes
+
+**Code Volume:**
+- Created: 2 new files (DateColumnDataSource.ts, ColumnDataSource.ts interface)
+- Modified: 5 files (GridManager.ts, NavigationManager.ts, GridRenderer.ts, ColumnRenderer.ts, EventTypes.ts)
+
+---
+
+## User Corrections & Course Changes
+
+### Correction #1: GridRenderer Event Rendering Violation
+
+**What Happened:**
+After conversation compaction, I mistakenly added event rendering logic directly into GridRenderer.
+
+**Code I Added (WRONG):**
+```typescript
+// GridRenderer.ts - renderColumnContainer()
+private renderColumnContainer(dates: Date[], events: ICalendarEvent[]): void {
+  dates.forEach(date => {
+    const eventsForDate = events.filter(event => {...});
+
+    // Created columns...
+
+    // ❌ WRONG: Rendering events directly in GridRenderer
+    this.renderColumnEvents(eventsForDate, eventsLayer);
+  });
+}
+
+// Added entire event layout logic to GridRenderer
+private renderColumnEvents() { ... }
+private renderGridGroup() { ... }
+private renderEvent() { ... }
+```
+
+**User Intervention:**
+```
+"hvorfor har du flyttet eventrendering iind i griidrendere?
+det er jo columnsrenderes opgave"
+```
+
+followed by:
+
+```
+"ja naturligivs da"
+```
+
+**Problem:**
+- GridRenderer should ONLY create grid structure (skeleton)
+- Event rendering is EventRenderingService's responsibility
+- ColumnRenderer creates columns, not GridRenderer's loop
+- Violated separation of concerns
+- Duplicated logic that already existed in DateEventRenderer
+
+**Correct Solution:**
+```typescript
+// GridRenderer.ts - renderColumnContainer()
+private renderColumnContainer(dates: Date[], events: ICalendarEvent[]): void {
+  // Delegate to ColumnRenderer
+  this.columnRenderer.render(columnContainer, {
+    dates: dates,
+    config: this.config
+  });
+  // Events rendered by EventRenderingService via GRID_RENDERED event
+}
+```
+
+**Lesson:** After conversation compaction, I lost context about architectural boundaries. GridRenderer = structure, EventRenderingService = events, ColumnRenderer = columns. Never mix responsibilities.
+
+---
+
+### Correction #2: NavigationManager Configuration Injection
+
+**What Happened:**
+I attempted to inject Configuration into NavigationManager so it could calculate dates.
+
+**User Intervention:**
+```
+"hvad er det her du har lavet... NavigationManager skal bruge Configuration
+for at få adgang til workweek settings, så den kan beregne dates.
+Lad mig opdatere det:
+
+ja det vi nok. Men hva dbruger GridManager det event tiil?"
+```
+
+**Problem:**
+- NavigationManager doesn't need to know about workweek settings
+- Date calculation should be DataSource's responsibility
+- NavigationManager should focus on animation, not data
+
+**Initial Wrong Approach:**
+```typescript
+// NavigationManager.ts
+constructor(..., config: Configuration) {
+  this.config = config;
+}
+
+private animateTransition() {
+  const workWeekSettings = this.config.getWorkWeekSettings();
+  const dates = this.dateService.getWorkWeekDates(targetWeek, workWeekSettings.workDays);
+  // ❌ NavigationManager calculating dates manually
+}
+```
+
+**Correct Solution:**
+```typescript
+// NavigationManager.ts
+constructor(..., config: Configuration) {
+  this.config = config;
+  this.dataSource = new DateColumnDataSource(dateService, config, this.currentWeek, 'week');
+}
+
+private animateTransition() {
+  this.dataSource.setCurrentDate(targetWeek);
+  const dates = this.dataSource.getColumns();
+  // ✅ DataSource calculates dates
+}
+```
+
+**Lesson:** NavigationManager needed Configuration, but not to calculate dates itself. It needed it to create a DataSource instance, which handles date calculation.
+
+---
+
+### Correction #3: GridManager Navigation Rendering Conflict
+
+**What Happened:**
+GridManager was calling `render()` when receiving NAVIGATION_COMPLETED event, creating conflict with NavigationManager's animation.
+
+**User Analysis:**
+I explained the problem flow:
+```
+1. NavigationManager creates NEW grid with animation
+2. After animation: emits NAVIGATION_COMPLETED
+3. GridManager listens and calls render() → updates OLD grid
+4. Result: Two grids, broken state
+```
+
+User response:
+```
+"ja" (approved the fix)
+```
+
+**Problem:**
+```typescript
+// GridManager.ts - BEFORE (WRONG)
+eventBus.on(CoreEvents.NAVIGATION_COMPLETED, (e: Event) => {
+  this.currentDate = detail.newDate;
+  this.dataSource.setCurrentDate(this.currentDate);
+  this.render(); // ❌ Re-renders, conflicts with NavigationManager's new grid
+});
+```
+
+**Correct Solution:**
+```typescript
+// GridManager.ts - AFTER (CORRECT)
+// Listen for navigation events from NavigationManager
+// NavigationManager has already created new grid with animation
+// GridManager only needs to update state, NOT re-render
+eventBus.on(CoreEvents.NAVIGATION_COMPLETED, (e: Event) => {
+  this.currentDate = detail.newDate;
+  this.dataSource.setCurrentDate(this.currentDate);
+  // Do NOT call render() - NavigationManager already created new grid
+});
+```
+
+**Lesson:** Two managers can't both render during navigation. NavigationManager owns animation rendering, GridManager only syncs state.
+
+---
+
+## Implementation Details
+
+### Phase 1: DateColumnDataSource Creation
+
+**File Created:** `src/datasources/DateColumnDataSource.ts`
+
+**Purpose:** Single source of truth for date calculation based on workweek settings.
+
+```typescript
+export class DateColumnDataSource implements IColumnDataSource {
+  private dateService: DateService;
+  private config: Configuration;
+  private currentDate: Date;
+  private currentView: CalendarView;
+
+  public getColumns(): Date[] {
+    switch (this.currentView) {
+      case 'week':
+        return this.getWeekDates();
+      case 'month':
+        return this.getMonthDates();
+      case 'day':
+        return [this.currentDate];
+    }
+  }
+
+  private getWeekDates(): Date[] {
+    const weekStart = this.getISOWeekStart(this.currentDate);
+    const workWeekSettings = this.config.getWorkWeekSettings();
+    return this.dateService.getWorkWeekDates(weekStart, workWeekSettings.workDays);
+  }
+}
+```
+
+**Key Methods:**
+- `getColumns()` - Returns Date[] based on current view
+- `setCurrentDate(date)` - Updates current date
+- `setCurrentView(view)` - Switches between day/week/month
+- `getType()` - Returns 'date' (vs 'resource' for future mode)
+
+---
+
+### Phase 2: GridManager Integration
+
+**File Modified:** `src/managers/GridManager.ts`
+
+**Before:**
+```typescript
+// GridManager calculated dates itself
+const weekStart = this.getISOWeekStart(this.currentDate);
+const workWeekSettings = this.config.getWorkWeekSettings();
+const dates = this.dateService.getWorkWeekDates(weekStart, workWeekSettings.workDays);
+```
+
+**After:**
+```typescript
+// GridManager uses DataSource
+constructor(...) {
+  this.dataSource = new DateColumnDataSource(dateService, config, this.currentDate, this.currentView);
+}
+
+public async render(): Promise<void> {
+  const dates = this.dataSource.getColumns(); // Single source of truth
+  const events = await this.eventManager.getEventsForPeriod(dates[0], dates[dates.length - 1]);
+
+  this.gridRenderer.renderGrid(this.container, this.currentDate, this.currentView, dates, events);
+
+  eventBus.emit(CoreEvents.GRID_RENDERED, {
+    container: this.container,
+    currentDate: this.currentDate,
+    dates: dates
+  });
+}
+```
+
+**Navigation Handling Fixed:**
+```typescript
+eventBus.on(CoreEvents.NAVIGATION_COMPLETED, (e: Event) => {
+  this.currentDate = detail.newDate;
+  this.dataSource.setCurrentDate(this.currentDate);
+  // Removed render() call - NavigationManager already created new grid
+});
+```
+
+---
+
+### Phase 3: NavigationManager DataSource Integration
+
+**File Modified:** `src/managers/NavigationManager.ts`
+
+**Added:**
+```typescript
+import { DateColumnDataSource } from '../datasources/DateColumnDataSource';
+import { Configuration } from '../configurations/CalendarConfig';
+
+constructor(..., config: Configuration) {
+  this.config = config;
+  this.dataSource = new DateColumnDataSource(dateService, config, this.currentWeek, 'week');
+}
+```
+
+**Animation Flow Updated:**
+```typescript
+private animateTransition(direction: 'prev' | 'next', targetWeek: Date): void {
+  // Update DataSource with target week and get dates
+  this.dataSource.setCurrentDate(targetWeek);
+  const dates = this.dataSource.getColumns();
+
+  // Create new grid with correct dates
+  newGrid = this.gridRenderer.createNavigationGrid(container, dates);
+
+  // Animate transition...
+
+  // After animation: emit NAVIGATION_COMPLETED
+  this.eventBus.emit(CoreEvents.NAVIGATION_COMPLETED, {
+    direction,
+    newDate: this.currentWeek
+  });
+}
+```
+
+---
+
+### Phase 4: GridRenderer Responsibility Cleanup
+
+**File Modified:** `src/renderers/GridRenderer.ts`
+
+**Removed:**
+- WorkHoursManager injection (ColumnRenderer handles it)
+- Event rendering logic (EventRenderingService handles it)
+- Column creation loop (ColumnRenderer handles it)
+
+**Kept:**
+- Grid skeleton creation (swp-grid-container, swp-time-grid)
+- Time axis rendering
+- Delegation to ColumnRenderer
+
+**Before (WRONG - after conversation compaction):**
+```typescript
+private renderColumnContainer(dates: Date[], events: ICalendarEvent[]): void {
+  dates.forEach(date => {
+    const column = document.createElement('swp-day-column');
+    // Apply work hours styling
+    this.applyWorkHoursStyling(column, date);
+    // Render events
+    this.renderColumnEvents(eventsForDate, eventsLayer);
+  });
+}
+```
+
+**After (CORRECT):**
+```typescript
+private renderColumnContainer(dates: Date[], events: ICalendarEvent[]): void {
+  // Delegate to ColumnRenderer
+  this.columnRenderer.render(columnContainer, {
+    dates: dates,
+    config: this.config
+  });
+  // Events rendered by EventRenderingService via GRID_RENDERED event
+}
+```
+
+---
+
+### Phase 5: ColumnRenderer Context Update
+
+**File Modified:** `src/renderers/ColumnRenderer.ts`
+
+**Context Interface Changed:**
+```typescript
+// Before
+export interface IColumnRenderContext {
+  currentWeek: Date;
+  config: Configuration;
+}
+
+// After
+export interface IColumnRenderContext {
+  dates: Date[];  // ← Receives dates instead of calculating them
+  config: Configuration;
+}
+```
+
+**Render Method Updated:**
+```typescript
+// Before
+render(columnContainer: HTMLElement, context: IColumnRenderContext): void {
+  const { currentWeek, config } = context;
+  const workWeekSettings = config.getWorkWeekSettings();
+  const dates = this.dateService.getWorkWeekDates(currentWeek, workWeekSettings.workDays);
+  // ❌ ColumnRenderer calculating dates
+}
+
+// After
+render(columnContainer: HTMLElement, context: IColumnRenderContext): void {
+  const { dates } = context;
+  // ✅ ColumnRenderer receives dates from DataSource
+
+  dates.forEach((date) => {
+    const column = document.createElement('swp-day-column');
+    this.applyWorkHoursToColumn(column, date);
+    // ...
+  });
+}
+```
+
+---
+
+## Architecture Flow
+
+### Before DataSource:
+
+```
+┌──────────────────┐
+│  GridManager     │ ← Calculates dates manually
+└────────┬─────────┘
+         │
+         ▼
+┌──────────────────┐
+│  GridRenderer    │ ← No dates parameter
+└────────┬─────────┘
+         │
+         ▼
+┌──────────────────┐
+│ ColumnRenderer   │ ← Calculates dates again (duplicate logic)
+└──────────────────┘
+
+NavigationManager: Also calculates dates separately
+```
+
+### After DataSource:
+
+```
+┌─────────────────────┐
+│ DateColumnDataSource│ ← Single source of truth for dates
+└──────────┬──────────┘
+           │
+      ┌────┴────────────────────┐
+      │                         │
+┌─────▼────────┐       ┌────────▼──────────┐
+│ GridManager  │       │ NavigationManager │
+└─────┬────────┘       └────────┬──────────┘
+      │                         │
+      │  dates[]                │  dates[]
+      │                         │
+      ▼                         ▼
+┌──────────────────┐   ┌──────────────────┐
+│  GridRenderer    │   │  GridRenderer    │
+└────────┬─────────┘   │ (createNavGrid)  │
+         │             └──────────────────┘
+         ▼
+┌──────────────────┐
+│ ColumnRenderer   │ ← Receives dates, creates columns
+└────────┬─────────┘
+         │
+         ▼
+┌──────────────────┐
+│ swp-day-column   │ ← Column structure with work hours
+└──────────────────┘
+
+EventRenderingService ← Listens to GRID_RENDERED, renders events
+```
+
+---
+
+## Responsibilities After Refactoring
+
+### DateColumnDataSource
+- ✅ Calculate dates based on view (day/week/month)
+- ✅ Apply workweek settings
+- ✅ Single source of truth for dates
+
+### GridManager
+- ✅ Coordinate rendering flow
+- ✅ Get dates from DataSource
+- ✅ Fetch events from EventManager
+- ✅ Call GridRenderer with dates + events
+- ✅ Emit GRID_RENDERED event
+- ❌ NOT calculate dates itself
+- ❌ NOT render during NAVIGATION_COMPLETED
+
+### NavigationManager
+- ✅ Handle animation
+- ✅ Use DataSource to get dates for new grid
+- ✅ Create new grid via GridRenderer.createNavigationGrid()
+- ✅ Emit NAVIGATION_COMPLETED after animation
+- ❌ NOT calculate dates manually
+
+### GridRenderer
+- ✅ Create grid skeleton structure
+- ✅ Render time axis
+- ✅ Delegate column creation to ColumnRenderer
+- ❌ NOT create columns directly
+- ❌ NOT render events
+- ❌ NOT handle work hours styling
+
+### ColumnRenderer
+- ✅ Receive dates from context
+- ✅ Create swp-day-column elements
+- ✅ Apply work hours styling
+- ✅ Create eventsLayer structure
+- ❌ NOT calculate dates itself
+
+### EventRenderingService
+- ✅ Listen to GRID_RENDERED event
+- ✅ Render events into columns
+- ✅ Handle event layout (stacked vs grid)
+- ❌ NOT be called directly by GridRenderer
+
+---
+
+## Challenges & Solutions
+
+### Challenge 1: Conversation Compaction Memory Loss
+
+**Issue:** After conversation compaction, I lost context about architectural boundaries and started violating separation of concerns.
+
+**Impact:**
+- Added event rendering to GridRenderer
+- Added column creation loop to GridRenderer
+- Duplicated logic that already existed
+
+**Solution:**
+User corrections guided me back to correct architecture:
+1. GridRenderer delegates to ColumnRenderer
+2. EventRenderingService handles events via GRID_RENDERED
+3. DataSource calculates dates, not managers
+
+**Lesson:** After conversation compaction, explicitly review architectural boundaries before implementing. Ask about responsibilities if unsure.
+
+---
+
+### Challenge 2: Navigation Rendering Conflict
+
+**Issue:** Both NavigationManager and GridManager tried to render during navigation, creating duplicate grids.
+
+**Root Cause:**
+```
+NavigationManager: Creates NEW grid with animation
+GridManager: Receives NAVIGATION_COMPLETED → renders AGAIN
+Result: Two grids, broken state
+```
+
+**Solution:**
+GridManager only updates state on NAVIGATION_COMPLETED, doesn't re-render:
+```typescript
+eventBus.on(CoreEvents.NAVIGATION_COMPLETED, (e: Event) => {
+  this.currentDate = detail.newDate;
+  this.dataSource.setCurrentDate(this.currentDate);
+  // Removed render() call
+});
+```
+
+---
+
+### Challenge 3: DataSource Scope Confusion
+
+**Issue:** Initially unsure whether NavigationManager should calculate dates or use DataSource.
+
+**User Guidance:**
+NavigationManager should use DateColumnDataSource just like GridManager, ensuring consistent date calculation.
+
+**Solution:**
+Both managers create their own DataSource instances:
+```typescript
+// GridManager
+this.dataSource = new DateColumnDataSource(dateService, config, this.currentDate, this.currentView);
+
+// NavigationManager
+this.dataSource = new DateColumnDataSource(dateService, config, this.currentWeek, 'week');
+```
+
+---
+
+## Navigation Flow (Final)
+
+### User Clicks "Next Week":
+
+```
+1. NavigationButtons
+   ├─ Calculates newDate (next week)
+   └─ emit NAV_BUTTON_CLICKED { direction: 'next', newDate }
+
+2. NavigationManager (listens to NAV_BUTTON_CLICKED)
+   ├─ Updates DataSource with newDate
+   ├─ Gets dates from DataSource.getColumns()
+   ├─ Creates NEW grid: createNavigationGrid(dates)
+   ├─ Animates slide transition (old grid out, new grid in)
+   └─ After animation: emit NAVIGATION_COMPLETED { direction: 'next', newDate }
+
+3. GridManager (listens to NAVIGATION_COMPLETED)
+   ├─ Updates currentDate
+   ├─ Updates dataSource.setCurrentDate()
+   └─ Does NOT call render() ← Key fix!
+
+4. EventRenderingService (listens to GRID_RENDERED - emitted during step 2)
+   ├─ Reads GRID_RENDERED payload { container, dates }
+   ├─ Fetches events for date range
+   └─ Renders events into new grid's columns
+```
+
+**Result:** Single grid created by NavigationManager with animation, events rendered by EventRenderingService, GridManager stays in sync.
+
+---
+
+## Files Modified
+
+### Created:
+1. `src/types/ColumnDataSource.ts` - IColumnDataSource interface
+2. `src/datasources/DateColumnDataSource.ts` - Date-based DataSource implementation
+
+### Modified:
+1. `src/managers/GridManager.ts`
+   - Added DateColumnDataSource
+   - Removed date calculation logic
+   - Fixed NAVIGATION_COMPLETED handler (removed render() call)
+
+2. `src/managers/NavigationManager.ts`
+   - Added DateColumnDataSource
+   - Uses DataSource.getColumns() instead of manual calculation
+   - Added Configuration injection
+
+3. `src/renderers/GridRenderer.ts`
+   - Removed WorkHoursManager dependency
+   - Removed event rendering logic (corrected after mistake)
+   - Removed column creation loop (delegates to ColumnRenderer)
+   - Updated createNavigationGrid() to accept dates array
+
+4. `src/renderers/ColumnRenderer.ts`
+   - Changed IColumnRenderContext to receive dates array
+   - Removed date calculation logic
+   - Simplified render() method
+
+5. `src/types/EventTypes.ts`
+   - No changes needed (considered adding skipRender flag but not required)
+
+---
+
+## Test Results
+
+### Build Status:
+```bash
+npm run build
+# ✅ Success
+# Total transform time: 1105.12ms
+# No TypeScript errors
+```
+
+### Manual Testing Required:
+- ❓ Navigation animation works correctly
+- ❓ Events render after navigation
+- ❓ Work hours styling applied
+- ❓ Workweek preset changes reflected
+
+**Note:** No automated tests exist for navigation flow or DataSource.
+
+---
+
+## Lessons Learned
+
+### 1. Conversation Compaction Awareness
+- **Problem:** Lost architectural context after compaction
+- **Impact:** Violated separation of concerns, added code to wrong places
+- **Solution:** After compaction, explicitly review architectural boundaries before coding
+- **Prevention:** Ask user to confirm responsibilities if unsure
+
+### 2. Separation of Concerns Is Critical
+- **GridRenderer:** Structure only
+- **ColumnRenderer:** Columns only
+- **EventRenderingService:** Events only
+- **DataSource:** Dates only
+- **Mixing these leads to maintenance hell**
+
+### 3. Single Source of Truth Pattern
+- **Before:** 3 places calculated dates (GridManager, ColumnRenderer, NavigationManager)
+- **After:** 1 place calculates dates (DateColumnDataSource)
+- **Benefit:** Change workweek logic once, applies everywhere
+
+### 4. Event-Driven Rendering Conflicts
+- Two managers can't both render on same event
+- NavigationManager owns animation rendering
+- GridManager only syncs state during navigation
+- Clear ownership prevents bugs
+
+### 5. Dependency Injection Must Match Responsibility
+- GridRenderer doesn't need WorkHoursManager (ColumnRenderer does)
+- NavigationManager needs Configuration (to create DataSource)
+- Only inject what's actually used
+
+---
+
+## Future Considerations
+
+### Potential Improvements
+
+1. **Resource-Based View Support**
+   - Create `ResourceColumnDataSource` implementing `IColumnDataSource`
+   - Returns resource columns instead of date columns
+   - Switch between DateColumnDataSource and ResourceColumnDataSource based on view mode
+
+2. **DataSource Caching**
+   - Cache calculated dates to avoid recalculation
+   - Invalidate cache on workweek settings change
+   - Performance optimization for frequent navigation
+
+3. **Navigation Testing**
+   - Add integration tests for navigation flow
+   - Test animation + event rendering coordination
+   - Verify no duplicate grids created
+
+4. **DataSource Configuration**
+   - Allow DataSource to be configured via DI container
+   - Support custom DataSource implementations
+   - Enable A/B testing of different date calculation strategies
+
+---
+
+## Code Statistics
+
+### Lines Changed:
+- Created: ~150 lines (DateColumnDataSource + interface)
+- Modified: ~80 lines (GridManager, NavigationManager, GridRenderer, ColumnRenderer)
+- Removed: ~60 lines (duplicate date calculations, event rendering in GridRenderer)
+- Net: +170 lines
+
+### Complexity:
+- Cyclomatic complexity reduced (centralized date logic)
+- Coupling reduced (fewer dependencies in GridRenderer)
+- Cohesion improved (each class has single responsibility)
+
+---
+
+## Production Readiness
+
+### ✅ Ready for Testing
+
+**Confidence Level:** Medium-High
+
+**Reasons:**
+1. Build succeeds without errors
+2. Architecture follows separation of concerns
+3. All architectural violations corrected
+4. User-guided course corrections applied
+
+**Concerns:**
+1. No automated tests for navigation flow
+2. Manual testing required
+3. Event rendering after navigation not verified
+4. DataSource not tested with different workweek configs
+
+**Testing Checklist:**
+- [ ] Navigate next/previous week
+- [ ] Verify events render after animation
+- [ ] Check work hours styling applied
+- [ ] Change workweek preset and navigate
+- [ ] Verify no duplicate grids created
+- [ ] Test navigation while events are being dragged (edge case)
+
+**Rollback Plan:**
+If navigation breaks:
+1. Git revert to before DataSource implementation
+2. Restore direct date calculations in managers
+3. Restore GridManager render() call on NAVIGATION_COMPLETED
+
+---
+
+## Conclusion
+
+Successfully implemented DataSource architecture despite initial architectural violations caused by conversation compaction. User corrections guided the implementation back to correct separation of concerns.
+
+The migration process revealed:
+1. Importance of maintaining architectural awareness after conversation compaction
+2. Value of centralized data calculation (DataSource pattern)
+3. Critical need for clear responsibility boundaries
+4. How event-driven architecture requires careful coordination
+
+**Key Success:** Single source of truth for dates, clean separation of structure/columns/events rendering, navigation rendering conflict resolved.
+
+**Key Learning:** After conversation compaction, always verify architectural boundaries before implementing.
+
+**Status:** ✅ Implementation complete, ready for manual testing.

src/datasources/DateColumnDataSource.ts

@@ -1,4 +1,4 @@
-import { IColumnDataSource } from '../types/ColumnDataSource';
+import { IColumnDataSource, IColumnInfo } from '../types/ColumnDataSource';
 import { DateService } from '../utils/DateService';
 import { Configuration } from '../configurations/CalendarConfig';
 import { CalendarView } from '../types/CalendarTypes';
@@ -32,17 +32,28 @@ export class DateColumnDataSource implements IColumnDataSource {
   /**
    * Get columns (dates) to display
    */
-  public getColumns(): Date[] {
+  public getColumns(): IColumnInfo[] {
+    let dates: Date[];
+
     switch (this.currentView) {
       case 'week':
-        return this.getWeekDates();
+        dates = this.getWeekDates();
+        break;
       case 'month':
-        return this.getMonthDates();
+        dates = this.getMonthDates();
+        break;
       case 'day':
-        return [this.currentDate];
+        dates = [this.currentDate];
+        break;
       default:
-        return this.getWeekDates();
+        dates = this.getWeekDates();
     }
+
+    // Convert Date[] to IColumnInfo[]
+    return dates.map(date => ({
+      identifier: this.dateService.formatISODate(date),
+      data: date
+    }));
   }
 
   /**

src/managers/DragDropManager.ts

@@ -738,7 +738,7 @@ export class DragDropManager {
     }
 
     const dragMouseLeavePayload: IDragMouseLeaveHeaderEventPayload = {
-      targetDate: targetColumn.date,
+      targetColumn: targetColumn,
       mousePosition: position,
       originalElement: this.originalElement,
       draggedClone: this.draggedClone

src/managers/GridManager.ts

@@ -87,20 +87,21 @@ export class GridManager {
       return;
     }
 
-    // Get dates from datasource - single source of truth
+    // Get columns from datasource - single source of truth
-    const dates = this.dataSource.getColumns();
+    const columns = this.dataSource.getColumns();
 
-    // Get events for the period from EventManager
+    // Extract dates for EventManager query
+    const dates = columns.map(col => col.data as Date);
     const startDate = dates[0];
     const endDate = dates[dates.length - 1];
     const events = await this.eventManager.getEventsForPeriod(startDate, endDate);
 
-    // Delegate to GridRenderer with dates and events
+    // Delegate to GridRenderer with columns and events
     this.gridRenderer.renderGrid(
       this.container,
       this.currentDate,
       this.currentView,
-      dates,
+      columns,
       events
     );
 
@@ -108,7 +109,7 @@ export class GridManager {
     eventBus.emit(CoreEvents.GRID_RENDERED, {
       container: this.container,
       currentDate: this.currentDate,
-      dates: dates
+      columns: columns
     });
   }
 }

src/managers/HeaderManager.ts

@@ -4,6 +4,7 @@ import { CoreEvents } from '../constants/CoreEvents';
 import { IHeaderRenderer, IHeaderRenderContext } from '../renderers/DateHeaderRenderer';
 import { IDragMouseEnterHeaderEventPayload, IDragMouseLeaveHeaderEventPayload, IHeaderReadyEventPayload } from '../types/EventTypes';
 import { ColumnDetectionUtils } from '../utils/ColumnDetectionUtils';
+import { DateColumnDataSource } from '../datasources/DateColumnDataSource';
 
 /**
  * HeaderManager - Handles all header-related event logic
@@ -13,10 +14,12 @@ import { ColumnDetectionUtils } from '../utils/ColumnDetectionUtils';
 export class HeaderManager {
   private headerRenderer: IHeaderRenderer;
   private config: Configuration;
+  private dataSource: DateColumnDataSource;
 
-  constructor(headerRenderer: IHeaderRenderer, config: Configuration) {
+  constructor(headerRenderer: IHeaderRenderer, config: Configuration, dataSource: DateColumnDataSource) {
     this.headerRenderer = headerRenderer;
     this.config = config;
+    this.dataSource = dataSource;
 
     // Bind handler methods for event listeners
     this.handleDragMouseEnterHeader = this.handleDragMouseEnterHeader.bind(this);
@@ -43,11 +46,11 @@ export class HeaderManager {
    * Handle drag mouse enter header event
    */
   private handleDragMouseEnterHeader(event: Event): void {
-    const { targetColumn: targetDate, mousePosition, originalElement, draggedClone: cloneElement } =
+    const { targetColumn, mousePosition, originalElement, draggedClone: cloneElement } =
       (event as CustomEvent<IDragMouseEnterHeaderEventPayload>).detail;
 
     console.log('🎯 HeaderManager: Received drag:mouseenter-header', {
-      targetDate,
+      targetColumn: targetColumn.identifier,
       originalElement: !!originalElement,
       cloneElement: !!cloneElement
     });
@@ -57,11 +60,11 @@ export class HeaderManager {
    * Handle drag mouse leave header event
    */
   private handleDragMouseLeaveHeader(event: Event): void {
-    const { targetDate, mousePosition, originalElement, draggedClone: cloneElement } =
+    const { targetColumn, mousePosition, originalElement, draggedClone: cloneElement } =
       (event as CustomEvent<IDragMouseLeaveHeaderEventPayload>).detail;
 
     console.log('🚪 HeaderManager: Received drag:mouseleave-header', {
-      targetDate,
+      targetColumn: targetColumn?.identifier,
       originalElement: !!originalElement,
       cloneElement: !!cloneElement
     });
@@ -111,9 +114,13 @@ export class HeaderManager {
     // Clear existing content
     calendarHeader.innerHTML = '';
 
+    // Update DataSource with current date and get columns
+    this.dataSource.setCurrentDate(currentDate);
+    const columns = this.dataSource.getColumns();
+
     // Render new header content using injected renderer
     const context: IHeaderRenderContext = {
-      currentWeek: currentDate,
+      columns: columns,
       config: this.config
     };
 

src/managers/NavigationManager.ts

@@ -191,12 +191,12 @@ export class NavigationManager {
     console.log('Calling GridRenderer instead of NavigationRenderer');
     console.log('Target week:', targetWeek);
 
-    // Update DataSource with target week and get dates
+    // Update DataSource with target week and get columns
     this.dataSource.setCurrentDate(targetWeek);
-    const dates = this.dataSource.getColumns();
+    const columns = this.dataSource.getColumns();
 
     // Always create a fresh container for consistent behavior
-    newGrid = this.gridRenderer.createNavigationGrid(container, dates);
+    newGrid = this.gridRenderer.createNavigationGrid(container, columns);
 
     console.groupEnd();
 

src/renderers/ColumnRenderer.ts

@@ -3,6 +3,7 @@
 import { Configuration } from '../configurations/CalendarConfig';
 import { DateService } from '../utils/DateService';
 import { WorkHoursManager } from '../managers/WorkHoursManager';
+import { IColumnInfo } from '../types/ColumnDataSource';
 
 /**
  * Interface for column rendering strategies
@@ -15,7 +16,7 @@ export interface IColumnRenderer {
  * Context for column rendering
  */
 export interface IColumnRenderContext {
-  dates: Date[];
+  columns: IColumnInfo[];
   config: Configuration;
 }
 
@@ -35,11 +36,13 @@ export class DateColumnRenderer implements IColumnRenderer {
   }
 
   render(columnContainer: HTMLElement, context: IColumnRenderContext): void {
-    const { dates } = context;
+    const { columns } = context;
 
-    dates.forEach((date) => {
+    columns.forEach((columnInfo) => {
+      const date = columnInfo.data as Date;
       const column = document.createElement('swp-day-column');
-      (column as any).dataset.date = this.dateService.formatISODate(date);
+
+      column.dataset.columnId = columnInfo.identifier;
 
       // Apply work hours styling
       this.applyWorkHoursToColumn(column, date);

src/renderers/DateHeaderRenderer.ts

@@ -2,6 +2,7 @@
 
 import { Configuration } from '../configurations/CalendarConfig';
 import { DateService } from '../utils/DateService';
+import { IColumnInfo } from '../types/ColumnDataSource';
 
 /**
  * Interface for header rendering strategies
@@ -15,7 +16,7 @@ export interface IHeaderRenderer {
  * Context for header rendering
  */
 export interface IHeaderRenderContext {
-  currentWeek: Date;
+  columns: IColumnInfo[];
   config: Configuration;
 }
 
@@ -26,26 +27,22 @@ export class DateHeaderRenderer implements IHeaderRenderer {
   private dateService!: DateService;
 
   render(calendarHeader: HTMLElement, context: IHeaderRenderContext): void {
-    const { currentWeek, config } = context;
+    const { columns, config } = context;
 
     // FIRST: Always create all-day container as part of standard header structure
     const allDayContainer = document.createElement('swp-allday-container');
     calendarHeader.appendChild(allDayContainer);
 
     // Initialize date service with timezone and locale from config
-    const timezone = config.timeFormatConfig.timezone;
     const locale = config.timeFormatConfig.locale;
     this.dateService = new DateService(config);
 
-    const workWeekSettings = config.getWorkWeekSettings();
+    columns.forEach((columnInfo) => {
-    const dates = this.dateService.getWorkWeekDates(currentWeek, workWeekSettings.workDays);
+      const date = columnInfo.data as Date;
-    const weekDays = config.dateViewSettings.weekDays;
-    const daysToShow = dates.slice(0, weekDays);
-
-    daysToShow.forEach((date, index) => {
       const header = document.createElement('swp-day-header');
+
       if (this.dateService.isSameDay(date, new Date())) {
-        (header as any).dataset.today = 'true';
+        header.dataset.today = 'true';
       }
 
       const dayName = this.dateService.getDayName(date, 'long', locale).toUpperCase();
@@ -54,7 +51,8 @@ export class DateHeaderRenderer implements IHeaderRenderer {
         <swp-day-name>${dayName}</swp-day-name>
         <swp-day-date>${date.getDate()}</swp-day-date>
       `;
-      (header as any).dataset.date = this.dateService.formatISODate(date);
+
+      header.dataset.columnId = columnInfo.identifier;
 
       calendarHeader.appendChild(header);
     });

src/renderers/EventRenderer.ts

@@ -390,14 +390,15 @@ export class DateEventRenderer implements IEventRenderer {
   }
 
   protected getEventsForColumn(column: HTMLElement, events: ICalendarEvent[]): ICalendarEvent[] {
-    const columnDate = column.dataset.date;
+    const columnId = column.dataset.columnId;
-    if (!columnDate) {
+    if (!columnId) {
       return [];
     }
 
     // Create start and end of day for interval overlap check
-    const columnStart = this.dateService.parseISO(`${columnDate}T00:00:00`);
+    // In date-mode, columnId is ISO date string like "2024-11-13"
-    const columnEnd = this.dateService.parseISO(`${columnDate}T23:59:59.999`);
+    const columnStart = this.dateService.parseISO(`${columnId}T00:00:00`);
+    const columnEnd = this.dateService.parseISO(`${columnId}T23:59:59.999`);
 
     const columnEvents = events.filter(event => {
       // Interval overlap: event overlaps with column day if event.start < columnEnd AND event.end > columnStart

src/renderers/EventRendererManager.ts

@@ -91,12 +91,15 @@ export class EventRenderingService {
      * Handle GRID_RENDERED event - render events in the current grid
      */
     private handleGridRendered(event: CustomEvent): void {
-        const { container, dates } = event.detail;
+        const { container, columns } = event.detail;
 
-        if (!container || !dates || dates.length === 0) {
+        if (!container || !columns || columns.length === 0) {
             return;
         }
 
+        // Extract dates from columns
+        const dates = columns.map((col: any) => col.data as Date);
+
         // Calculate startDate and endDate from dates array
         const startDate = dates[0];
         const endDate = dates[dates.length - 1];

src/renderers/GridRenderer.ts

@@ -5,6 +5,7 @@ import { eventBus } from '../core/EventBus';
 import { DateService } from '../utils/DateService';
 import { CoreEvents } from '../constants/CoreEvents';
 import { TimeFormatter } from '../utils/TimeFormatter';
+import { IColumnInfo } from '../types/ColumnDataSource';
 
 /**
  * GridRenderer - Centralized DOM rendering for calendar grid structure
@@ -111,7 +112,7 @@ export class GridRenderer {
     grid: HTMLElement,
     currentDate: Date,
     view: CalendarView = 'week',
-    dates: Date[] = [],
+    columns: IColumnInfo[] = [],
     events: ICalendarEvent[] = []
   ): void {
 
@@ -124,10 +125,10 @@ export class GridRenderer {
 
     // Only clear and rebuild if grid is empty (first render)
     if (grid.children.length === 0) {
-      this.createCompleteGridStructure(grid, currentDate, view, dates, events);
+      this.createCompleteGridStructure(grid, currentDate, view, columns, events);
     } else {
       // Optimized update - only refresh dynamic content
-      this.updateGridContent(grid, currentDate, view, dates, events);
+      this.updateGridContent(grid, currentDate, view, columns, events);
     }
   }
 
@@ -151,7 +152,7 @@ export class GridRenderer {
     grid: HTMLElement,
     currentDate: Date,
     view: CalendarView,
-    dates: Date[],
+    columns: IColumnInfo[],
     events: ICalendarEvent[]
   ): void {
     // Create all elements in memory first for better performance
@@ -167,7 +168,7 @@ export class GridRenderer {
     fragment.appendChild(timeAxis);
 
     // Create grid container with caching
-    const gridContainer = this.createOptimizedGridContainer(dates, events);
+    const gridContainer = this.createOptimizedGridContainer(columns, events);
     this.cachedGridContainer = gridContainer;
     fragment.appendChild(gridContainer);
 
@@ -218,7 +219,7 @@ export class GridRenderer {
    * @returns Complete grid container element
    */
   private createOptimizedGridContainer(
-    dates: Date[],
+    columns: IColumnInfo[],
     events: ICalendarEvent[]
   ): HTMLElement {
     const gridContainer = document.createElement('swp-grid-container');
@@ -237,7 +238,7 @@ export class GridRenderer {
 
     // Create column container
     const columnContainer = document.createElement('swp-day-columns');
-    this.renderColumnContainer(columnContainer, dates, events);
+    this.renderColumnContainer(columnContainer, columns, events);
     timeGrid.appendChild(columnContainer);
 
     scrollableContent.appendChild(timeGrid);
@@ -259,12 +260,12 @@ export class GridRenderer {
    */
   private renderColumnContainer(
     columnContainer: HTMLElement,
-    dates: Date[],
+    columns: IColumnInfo[],
     events: ICalendarEvent[]
   ): void {
     // Delegate to ColumnRenderer
     this.columnRenderer.render(columnContainer, {
-      dates: dates,
+      columns: columns,
       config: this.config
     });
   }
@@ -285,14 +286,14 @@ export class GridRenderer {
     grid: HTMLElement,
     currentDate: Date,
     view: CalendarView,
-    dates: Date[],
+    columns: IColumnInfo[],
     events: ICalendarEvent[]
   ): void {
     // Update column container if needed
     const columnContainer = grid.querySelector('swp-day-columns');
     if (columnContainer) {
       columnContainer.innerHTML = '';
-      this.renderColumnContainer(columnContainer as HTMLElement, dates, events);
+      this.renderColumnContainer(columnContainer as HTMLElement, columns, events);
     }
   }
   /**
@@ -308,9 +309,9 @@ export class GridRenderer {
    * @param dates - Array of dates to render
    * @returns New grid element ready for animation
    */
-  public createNavigationGrid(parentContainer: HTMLElement, dates: Date[]): HTMLElement {
+  public createNavigationGrid(parentContainer: HTMLElement, columns: IColumnInfo[]): HTMLElement {
     // Create grid structure without events (events rendered by EventRenderingService)
-    const newGrid = this.createOptimizedGridContainer(dates, []);
+    const newGrid = this.createOptimizedGridContainer(columns, []);
 
     // Position new grid for animation - NO transform here, let Animation API handle it
     newGrid.style.position = 'absolute';

src/types/ColumnDataSource.ts

@@ -1,3 +1,12 @@
+/**
+ * Column information container
+ * Contains both identifier and actual data for a column
+ */
+export interface IColumnInfo {
+  identifier: string;      // "2024-11-13" (date mode) or "person-1" (resource mode)
+  data: Date | any;        // Date for date-mode, IResource for resource-mode
+}
+
 /**
  * IColumnDataSource - Defines the contract for providing column data
  *
@@ -6,10 +15,10 @@
  */
 export interface IColumnDataSource {
   /**
-   * Get the list of column identifiers to render
+   * Get the list of columns to render
-   * @returns Array of identifiers (dates or resource IDs)
+   * @returns Array of column information
    */
-  getColumns(): Date[];
+  getColumns(): IColumnInfo[];
 
   /**
    * Get the type of columns this datasource provides

src/types/EventTypes.ts

@@ -60,7 +60,7 @@ export interface IDragMouseEnterHeaderEventPayload {
 
 // Drag mouse leave header event payload
 export interface IDragMouseLeaveHeaderEventPayload {
-  targetDate: string | null;
+  targetColumn: IColumnBounds | null;
   mousePosition: IMousePosition;
   originalElement: HTMLElement| null;
   draggedClone: HTMLElement| null;

src/utils/ColumnDetectionUtils.ts

@@ -7,7 +7,7 @@ import { IMousePosition } from "../types/DragDropTypes";
 
 
 export interface IColumnBounds {
-    date: string;
+    identifier: string;
     left: number;
     right: number;
     boundingClientRect: DOMRect,
@@ -31,15 +31,15 @@ export class ColumnDetectionUtils {
         // Cache hver kolonnes x-grænser
         columns.forEach(column => {
             const rect = column.getBoundingClientRect();
-            const date = (column as HTMLElement).dataset.date;
+            const identifier = (column as HTMLElement).dataset.columnId;
 
-            if (date) {
+            if (identifier) {
                 this.columnBoundsCache.push({
                     boundingClientRect : rect,
                     element: column as HTMLElement,
-                    date,
+                    identifier,
                     left: rect.left,
-                    right: rect.right, 
+                    right: rect.right,
                     index: index++
                 });
             }
@@ -68,18 +68,15 @@ export class ColumnDetectionUtils {
     }
 
     /**
-     * Get column bounds by Date
+     * Get column bounds by identifier
      */
-    public static getColumnBoundsByDate(date: Date): IColumnBounds | null {
+    public static getColumnBoundsByIdentifier(identifier: string): IColumnBounds | null {
         if (this.columnBoundsCache.length === 0) {
             this.updateColumnBoundsCache();
         }
 
-        // Convert Date to YYYY-MM-DD format
+        // Find column that matches the identifier
-        let dateString = date.toISOString().split('T')[0];
+        let column = this.columnBoundsCache.find(col => col.identifier === identifier);
-
-        // Find column that matches the date
-        let column = this.columnBoundsCache.find(col => col.date === dateString);
         return column || null;
     }
 
@@ -96,15 +93,15 @@ export class ColumnDetectionUtils {
         // Cache hver kolonnes x-grænser
         dayColumns.forEach(column => {
             const rect = column.getBoundingClientRect();
-            const date = (column as HTMLElement).dataset.date;
+            const identifier = (column as HTMLElement).dataset.columnId;
 
-            if (date) {
+            if (identifier) {
                 dayHeaders.push({
                     boundingClientRect : rect,
                     element: column as HTMLElement,
-                    date,
+                    identifier,
                     left: rect.left,
-                    right: rect.right, 
+                    right: rect.right,
                     index: index++
                 });
             }