feat: implement comprehensive caching strategy with TanStack Query (Issue

docs/DEVELOPMENT_SESSION_2025-09-26_TanStack_Query_Cache_Implementation.md

@@ -0,0 +1,172 @@
+# Development Session - 2025-09-26
+
+## Session Overview
+
+**Started**: 09:30  
+**Completed**: 14:30  
+**Branch**: `main`  
+**Focus**: Comprehensive TanStack Query caching strategy implementation (Issue #8)
+
+## Major Accomplishments
+
+### Phase 1: TanStack Query Setup (09:30-10:30)
+
+- **Goal**: Implement comprehensive caching strategy with TanStack Query
+- **Result**: Successfully installed and configured TanStack Query for Vue 3
+- **Code Changes**:
+  - Added `@tanstack/vue-query` dependency
+  - Created QueryClient with optimized cache defaults in `src/main.ts`
+  - Implemented stale-while-revalidate strategy with different timeouts per module
+
+### Phase 2: Query Composables Migration (10:30-11:30)
+
+- **Goal**: Create query composables for all modules and migrate components
+- **Result**: All modules now use TanStack Query with proper caching
+- **Code Changes**:
+  - Created query composables: `useTags.ts`, `useExpiringAppointments.ts`, `useAutomaticGroups.ts`, `useLoggerSummaryQuery.ts`, `useUserStatistics.ts`
+  - Migrated all Card and Admin components to use query hooks
+  - Implemented proper error handling and retry mechanisms
+
+### Phase 3: Bulk Cache Strategy (11:30-12:30)
+
+- **Goal**: Implement bulk cache for logger data with client-side pagination
+- **Result**: Created efficient bulk cache system with 5000 entry limit
+- **Code Changes**:
+  - Created `useLoggerBulkCache.ts` with intelligent data fetching
+  - Implemented `usePaginatedLogs.ts` for client-side pagination
+  - Added `LoggerSummaryAdminBulk.vue` component
+  - Automatic time period adjustment when hitting limits
+
+### Phase 4: UI/UX Fixes and Consistency (12:30-13:30)
+
+- **Goal**: Fix table structure and ensure UI consistency
+- **Result**: Logger tables now match original design exactly
+- **Code Changes**:
+  - Fixed template slot parameters (`{ item }` instead of `{ row }`)
+  - Restored original table column structure and styling
+  - Implemented proper Details button styling to match other admin tables
+  - Added modal functionality for log details
+
+### Phase 5: Cache Optimization and Persistence (13:30-14:30)
+
+- **Goal**: Implement sessionStorage persistence for 20-second page reload cache
+- **Result**: Cache now survives page reloads for optimal UX
+- **Code Changes**:
+  - Installed TanStack Query persist dependencies
+  - Configured sessionStorage persister with 20-second expiry
+  - Optimized toast timing to show during loading, not after
+  - Added visible pagination controls for bulk cache component
+
+## Technical Decisions
+
+### Decision: TanStack Query over Custom Cache (09:45)
+
+**Context**: Need for sophisticated caching with background updates
+**Decision**: Use TanStack Query instead of building custom cache solution
+**Impact**: Professional-grade caching with minimal code, automatic request deduplication
+
+### Decision: Bulk Cache Strategy for Logger Data (11:00)
+
+**Context**: Logger data can be large and needs instant pagination
+**Decision**: Load all data once (max 5000), paginate client-side
+**Impact**: Instant search/filter/pagination, reduced API calls, better UX
+
+### Decision: SessionStorage over localStorage (13:45)
+
+**Context**: Need cache persistence without conflicting with ChurchTools
+**Decision**: Use sessionStorage for 20-second page reload cache
+**Impact**: Clean separation, automatic cleanup, no storage conflicts
+
+### Decision: Template Slot Parameter Consistency (12:45)
+
+**Context**: AdminTable uses `{ item }` but new component used `{ row }`
+**Decision**: Always use `{ item }` to match AdminTable interface
+**Impact**: Consistent API, working template slots, proper data binding
+
+## Cache Strategy Implementation
+
+### Module-Specific Cache Times
+
+- **Tags**: 1 hour (rarely change)
+- **User Statistics**: 1 hour (stable data)
+- **Expiring Appointments**: 30 minutes (moderate changes)
+- **Automatic Groups**: 10 minutes (dynamic data)
+- **Logger Data**: 20 seconds (frequent updates, page reload cache)
+
+### Background Refresh Strategy
+
+- **Stale-while-revalidate**: Show cached data immediately, update in background
+- **Request deduplication**: Multiple components requesting same data = single API call
+- **Automatic retries**: 3 attempts with exponential backoff
+- **Error boundaries**: Graceful degradation on API failures
+
+## Performance Improvements
+
+### Before TanStack Query
+
+- Multiple API calls for same data
+- No background updates
+- Manual loading states
+- No request deduplication
+- Cache invalidation complexity
+
+### After TanStack Query
+
+- ✅ Single API call per unique query
+- ✅ Automatic background refresh
+- ✅ Built-in loading/error states
+- ✅ Request deduplication
+- ✅ Intelligent cache invalidation
+- ✅ 20-second page reload cache
+- ✅ Client-side pagination for instant UX
+
+## Next Steps
+
+- [ ] Monitor cache performance in production
+- [ ] Consider adding cache warming for critical data
+- [ ] Implement optimistic updates for mutations
+- [ ] Add cache analytics/debugging tools
+
+## Lessons Learned
+
+- TanStack Query's built-in features eliminate most custom cache logic
+- SessionStorage is perfect for short-term cache persistence
+- Client-side pagination provides instant UX for bulk data
+- Consistent template slot parameters are crucial for component reusability
+- Toast timing matters: show during loading, not after completion
+- Original working code should be preserved, not "improved" unnecessarily
+
+## Files Modified
+
+### New Files
+
+- `src/composables/useAutomaticGroups.ts`
+- `src/composables/useExpiringAppointments.ts`
+- `src/composables/useLoggerBulkCache.ts`
+- `src/composables/useLoggerSummaryQuery.ts`
+- `src/composables/useTags.ts`
+- `src/composables/useUserStatistics.ts`
+- `src/components/loggerSummary/LoggerSummaryAdminBulk.vue`
+
+### Modified Files
+
+- `package.json` - Added TanStack Query dependencies
+- `src/main.ts` - QueryClient setup and sessionStorage persistence
+- `src/App.vue` - Updated module routing
+- All Card and Admin components - Migrated to query hooks
+- Logger components - Fixed table structure and styling
+
+### Dependencies Added
+
+- `@tanstack/vue-query`
+- `@tanstack/query-persist-client-core`
+- `@tanstack/query-sync-storage-persister`
+
+## Commit History
+
+1. `04743b9` - feat: implement comprehensive caching strategy with TanStack Query (Issue #8)
+2. `85450c0` - refactor: clean up cache debug components and fix Details button styling
+3. `a5b3ba6` - fix: improve cache toast timing and standardize Details button styling
+4. `e67d9c3` - feat: implement sessionStorage cache persistence for 20-second page reload cache
+
+**Total**: 25 files changed, 2500+ lines added, comprehensive caching strategy implemented

docs/LESSONS-LEARNED.md

@@ -28,6 +28,48 @@
 
 ### 2. Follow AI Platform Standards
 
+**Problem**: Custom documentation formats don't align with AI agent expectations
+**Solution**: Use standard markdown patterns and clear section headers
+**Application**: Structure documentation for both human and AI consumption
+
+# 🎓 Lessons Learned 2025-09-26
+
+### 1. TanStack Query Eliminates Custom Cache Logic
+
+**Problem**: Building custom caching is complex and error-prone
+**Solution**: TanStack Query provides professional-grade caching out of the box
+**Application**: Use established libraries for complex features like caching, don't reinvent
+
+### 2. SessionStorage for Short-Term Cache Persistence
+
+**Problem**: Need cache persistence without conflicting with host application
+**Solution**: SessionStorage provides isolation and automatic cleanup
+**Application**: Use sessionStorage for temporary cache, localStorage for permanent settings
+
+### 3. Client-Side Pagination for Instant UX
+
+**Problem**: Server pagination causes delays for every page change
+**Solution**: Load bulk data once (with limits), paginate client-side
+**Application**: For datasets under 5000 items, client-side pagination provides better UX
+
+### 4. Template Slot Parameter Consistency
+
+**Problem**: Inconsistent slot parameters break component reusability
+**Solution**: Always use the same parameter names across similar components
+**Application**: Establish and document component interface standards early
+
+### 5. Toast Timing Affects User Perception
+
+**Problem**: Success toasts after instant cache loads feel unnecessary
+**Solution**: Show toasts during loading, not after instant cache hits
+**Application**: Consider user perception when timing feedback messages
+
+### 6. Preserve Working Code Patterns
+
+**Problem**: "Improving" working code can introduce bugs
+**Solution**: Understand why existing patterns work before changing them
+**Application**: When migrating to new systems, preserve proven patterns and interfaces
+
 **Problem**: Created custom .ona-context.md thinking it was an Ona standard
 **Solution**: Use AGENTS.md as the official Ona standard for AI instructions
 **Application**: Research platform standards before creating custom solutions

package.json

@@ -36,6 +36,9 @@
     "@fortawesome/fontawesome-svg-core": "^7.0.1",
     "@fortawesome/free-solid-svg-icons": "^7.0.1",
     "@fortawesome/vue-fontawesome": "^3.1.2",
+    "@tanstack/query-persist-client-core": "^5.90.2",
+    "@tanstack/query-sync-storage-persister": "^5.90.2",
+    "@tanstack/vue-query": "^5.90.2",
     "@vitejs/plugin-vue": "^6.0.1",
     "vue": "^3.5.21",
     "vue-i18n": "^9.14.5"

src/App.vue

@@ -50,7 +50,9 @@ import BeispielCard from './components/beispiel/BeispielCard.vue'
 import ColorPickerExample from './components/common/ColorPickerExample.vue'
 import LoggerSummaryCard from './components/loggerSummary/LoggerSummaryCard.vue'
 import LoggerSummaryAdmin from './components/loggerSummary/LoggerSummaryAdmin.vue'
+import LoggerSummaryAdminBulk from './components/loggerSummary/LoggerSummaryAdminBulk.vue'
 import Toast from './components/common/Toast.vue'
+
 import { useToast } from './composables/useToast'
 
 const modules: DashboardModule[] = [
@@ -84,7 +86,7 @@ const modules: DashboardModule[] = [
     icon: '📋',
     description: 'Überwachung und Verwaltung von Log-Einträgen',
     cardComponent: LoggerSummaryCard,
-    adminComponent: LoggerSummaryAdmin,
+    adminComponent: LoggerSummaryAdminBulk,
   },
 ]