Agregarr is a full-stack Plex collection management application built with Next.js and Express, written in TypeScript. It automates the creation, synchronization, and visual customization of Plex collections by integrating with numerous external media sources and APIs including Trakt, TMDB, IMDb, Letterboxd, MDBList, AniList, MyAnimeList, Tautulli, Overseerr, Radarr, and Sonarr. The core architecture follows a monolithic pattern: a single server process running both the React frontend and Express backend, with SQLite persistence via TypeORM and a robust migration system. In production, Agregarr performs scheduled full syncs and incremental quick syncs of collection definitions to Plex, applies poster overlays based on configurable conditions (ratings, resolution, audio codecs, HDR formats), manages placeholder items for upcoming content, and can auto-request missing media through Radarr/Sonarr or Overseerr. The UI provides per-library collection views with drag-and-drop reordering, a visual poster editor with snap-to-guides and layering, an overlay editor with condition evaluation, and dashboard statistics from Tautulli. The codebase demonstrates solid engineering with clear separation of concerns, a template method pattern for collection sources (`BaseCollectionSync`), consistent API client wrappers, and modular UI form sections. However, it carries significant maintenance overhead from fragile web scraping (IMDb WAF, Cloudflare bypass), a large dependency surface including Chromium and Playwright, commented-out legacy code from its Overseerr fork, and reliance on external APIs that may change unexpectedly. The project is actively maintained with frequent migrations and feature additions.