[EPIC] Critical Data Persistence Implementation

[DrunkOnJava]

📋 Epic Overview

Problem Statement

The app currently uses in-memory storage causing complete data loss on app restart. This epic tracks the implementation of proper Core Data persistence across all repositories.

Success Criteria

• Core Data stack properly configured
• All repositories migrated from mock to Core Data implementations
• Data persists between app launches
• Migration strategy implemented for future schema changes
• Performance meets requirements (<100ms for common operations)

Sub-Issues

• #TBD - Implement Core Data Stack and PersistenceController
• #TBD - Create CoreDataItemRepository
• #TBD - Create CoreDataLocationRepository
• #TBD - Create CoreDataPhotoRepository
• #TBD - Create CoreDataReceiptRepository
• #TBD - Implement Data Migration Strategy
• #TBD - Update AppCoordinator Dependency Injection
• #TBD - Add Core Data Performance Tests

Technical Approach

1. Create centralized PersistenceController with Core Data stack
2. Implement repository protocols with Core Data backing
3. Replace mock implementations in AppCoordinator
4. Add comprehensive error handling
5. Implement migration strategy for schema evolution

Timeline

• Estimated Duration: 2-3 weeks
• Priority: P0 (Production Blocker)

Dependencies

• Core Data framework (already in project)
• No external dependencies

Risks & Mitigations

• Risk: Data migration failures
  • Mitigation: Implement versioned migration with fallback
• Risk: Performance degradation with large datasets
  • Mitigation: Add batch processing and background contexts

Acceptance Criteria

• All data persists between app launches
• Handles edge cases (disk full, corruption)
• Unit test coverage >90% for repositories
• Performance benchmarks pass (10,000+ items)
• Migration from v1 to v2 schema tested