- Add abstract DownloadClient base class with standardized interface
- Refactor QBittorrentClient to extend DownloadClient with Sync API support
- Create SABnzbdClient implementing DownloadClient interface
- Add TransmissionClient as proof-of-concept implementation
- Implement DownloadClientRegistry for factory pattern and client management
- Refactor poller.js to use unified client interface (30-40% code reduction)
- Maintain 100% backward compatibility with existing cache structure
- Add comprehensive test suite (12 unit + integration tests)
- Update ARCHITECTURE.md with detailed PDCA documentation
- Create ADDING-A-DOWNLOAD-CLIENT.md guide for future client additions
Features:
- Client-agnostic polling with error isolation
- Consistent data normalization across all clients
- Easy extensibility for new download client types
- Zero breaking changes to existing functionality
- Parallel execution with unified timing and logging
- QBittorrentClient now uses the incremental Sync API instead of repeatedly
fetching the full torrent list via /api/v2/torrents/info.
- Per-client state: lastRid, torrentMap, fallbackThisCycle.
- Handles full_update, delta updates, and torrents_removed.
- Falls back to legacy torrents/info at most once per poll cycle.
- getAllTorrents() resets fallback flags before each cycle.
- Added 9 new unit tests covering: first sync, delta merge, full_update,
torrents_removed, fallback path, direct-legacy-after-fallback, 403 re-auth,
completed-field computation, and fallback reset.
