Keeps Radarr/Sonarr quality upgrades out of "Recently Added" by keeping a ledger of the first date added per logical medium (movie or episode, identified by provider ids and the series) and restoring it on upgrades. - core logic without Jellyfin types (Reconciler, MediaKeys, GuardProcessor) - thread-safe ledger with atomic, debounced persistence - event processing via channel and background worker, seed on first start - scheduled task "Ledger synchronisieren", status API, configuration page - xUnit tests and a Jellyfin 12.2 integration test - Gitea workflows: build/test, release with jprm and manifest branch Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>