Design playlist syncing for multiple media servers#193
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This design document provides a complete architectural blueprint for implementing bidirectional playlist synchronization with Jellyfin, Emby, and Plex media servers. Key architectural components: - PlaylistSyncProvider interface for server-agnostic sync operations - PlaylistSyncCoordinator for managing sync lifecycle - Persistent sync queue with retry logic and priority handling - Conflict detection and resolution strategies - Repository interceptor pattern for change tracking The design follows Clean Architecture principles and maintains backward compatibility while providing a scalable, resilient foundation for bidirectional sync. Addresses: #102
Resolved all open questions from architecture review: 1. Default Conflict Resolution: Safe Auto-Merge - Union merge for additive operations (preserve all content) - User prompts only for destructive conflicts - Aligns with user expectation of not losing changes 2. Sync Frequency: Daily (user configurable) - Default: Daily background sync (battery-friendly) - Options: 15 min, hourly, 6 hours, daily, manual only - Manual "Sync Now" button for immediate sync 3. Sync Scope: Global per media server - Settings per server type (Jellyfin/Emby/Plex) - All playlists from enabled servers sync automatically - Simpler UX with less configuration overhead 4. Smart Playlists: No sync - Smart playlists are query-based and read-only - Focus sync effort on regular user playlists - Keep them local-only or read-only from server Additional enhancements: - Added detailed WorkManager configuration with constraints - Added PlaylistSyncPreferences structure for user settings - Expanded conflict resolution examples with scenarios - Added shouldSync() helper to exclude smart playlists - Updated document version to 1.1 with changelog Status: Ready for implementation Addresses: #102
This commit implements the foundational infrastructure for bidirectional playlist synchronization as outlined in PLAYLIST_SYNC_ARCHITECTURE.md. New Components: 1. Room Entities - SyncOperation: Persistent queue for sync operations - PlaylistSyncState: Tracks sync state and conflicts per playlist - Added enums: OperationType, SyncStatus, PlaylistSyncStatus 2. Database Layer - SyncOperationDao: CRUD operations for sync queue - PlaylistSyncStateDao: Sync state management - MIGRATION_40_41: Creates new tables with proper indexes and foreign keys - Updated Converters with Instant and enum type converters 3. Repository Layer - PlaylistSyncProvider: Interface for server-specific sync operations - SyncQueueRepository: Interface for sync queue management - LocalSyncQueueRepository: Room-based implementation 4. Dependency Injection - Added SyncQueueRepository to RepositoryModule - Database updated to version 41 with new entities Features: - Persistent sync queue survives app restarts - Priority-based operation ordering - Retry logic with configurable max retries - Conflict detection via content hashing - Foreign key constraints for data integrity - Comprehensive query support for sync status This establishes the foundation for: - Change tracking (Phase 3) - Background sync worker (Phase 4) - Conflict resolution (Phase 5) - Server-specific implementations (Phase 2, 7) Addresses: #102 Related: PLAYLIST_SYNC_ARCHITECTURE.md Phase 1
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📋 Overview
This PR introduces a comprehensive architecture design document for implementing bidirectional playlist synchronization between Shuttle2 and media servers (Jellyfin, Emby, Plex).
Addresses: #102 - Sync S2 playlist actions with Jellyfin server
🎯 Problem Statement
Currently, Shuttle2 supports one-way sync (pull playlists from media servers), but modifications made locally (adding/removing songs, renaming, deleting) don't sync back to the server. This creates:
Divergence between Shuttle2 and server state
Manual maintenance burden across multiple clients
Confusion when playlists differ between devices
✨ What's Included
Complete Architecture Document (PLAYLIST_SYNC_ARCHITECTURE.md)
A production-ready design covering:
Core Components
PlaylistSyncProvider interface for server-agnostic sync operations
PlaylistSyncCoordinator for managing sync lifecycle
SyncQueueRepository with persistent queue and retry logic
Repository interceptor pattern for non-invasive change tracking
Conflict Resolution Strategy
Safe Auto-Merge (default): Preserves all content when safe
User prompts only for destructive conflicts (renames, deletions)
Configurable preferences: Auto-merge, Always Local, Always Remote, Ask Me
Sync Configuration
Daily background sync (default, battery-friendly)
User configurable: 15 min, hourly, 6 hours, daily, or manual only
Global enable/disable per server type (Jellyfin/Emby/Plex)
Smart playlists excluded (query-based, read-only)
Media Server API Analysis
Jellyfin: Full CRUD support (with known bugs documented + workarounds)
Emby: Most stable API, excellent documentation
Plex: Comprehensive but different paradigm (URI-based)
Implementation Roadmap
8 phases over 12 weeks
Feature flags for gradual rollout
Backward compatible (no breaking changes)
Clear success criteria for each phase
🏗️ Architecture Highlights
Clean Architecture Principles
Presentation → Domain (Sync Coordinator) → Data (Repository + Providers) → Network
✅ SOLID principles throughout
✅ Repository pattern with reactive streams (Flow)
✅ Plugin architecture for media providers
✅ Offline-first with persistent sync queue
✅ Resilient error handling and conflict resolution
✅ Testable with clear component boundaries
Key Technical Decisions
| Decision | Choice | Rationale | |----------|--------|-----------| | Change Tracking | Repository Interceptor | Non-invasive, decorator pattern | | Sync Queue | Room database | Survives app restarts, queryable | | Conflict Detection | Content hashing | Efficient state comparison | | Background Sync | WorkManager | Battery-aware, constraint-based | | Scope | Global per server | Simple UX, less overhead |
📊 Design Decisions (Resolved)
All open questions have been answered:
✅ Conflict Resolution: Safe Auto-Merge (preserve content, minimize prompts)
✅ Sync Frequency: Daily default (user configurable)
✅ Sync Scope: Global per server type (Jellyfin/Emby/Plex toggles)
✅ Smart Playlists: No sync (query-based, read-only)
🚀 Next Steps
This PR contains architecture design only (no implementation code).
After merge:
Create implementation tickets for Phase 1 (Foundation)
Set up feature flags in build configuration
Begin database schema implementation
Follow the 8-phase rollout plan
📝 Document Details
Version: 1.1
Status: Ready for Implementation
Estimated Effort: 12 weeks (1 developer)
Priority: High (community requested)
Lines: ~1,230 lines of comprehensive documentation
🔍 Review Focus Areas
When reviewing, please pay attention to:
Architecture soundness - Does the component design follow best practices?
Scalability - Can this handle thousands of playlists across multiple servers?
User experience - Are the defaults sensible? Is conflict resolution intuitive?
Implementation feasibility - Is the phased approach realistic?
API compatibility - Are the server API capabilities accurately represented?