- Create ScanService class (src/server/services/scan_service.py)
- Use 'key' as primary series identifier throughout
- Include 'folder' as metadata only for display purposes
- Implement scan progress tracking via ProgressService
- Add callback classes for progress, error, and completion
- Support scan event subscription and broadcasting
- Maintain scan history with configurable limit
- Provide cancellation support for in-progress scans
- Create comprehensive unit tests (tests/unit/test_scan_service.py)
- 38 tests covering all functionality
- Test ScanProgress dataclass serialization
- Test callback classes (progress, error, completion)
- Test service lifecycle (start, cancel, status)
- Test event subscription and broadcasting
- Test key-based identification throughout
- Test singleton pattern
- Update infrastructure.md with ScanService documentation
- Document service overview and key features
- Document components and event types
- Document integration points
- Include usage example
- Update instructions.md
- Mark Task 3.4 as complete
- Mark Phase 3 as fully complete
- Remove finished task definition
Task: Phase 3, Task 3.4 - Update ScanService to Use Key
Completion Date: November 27, 2025
