Telemirror is a Telegram message mirroring application that uses the client API (Telethon) to forward messages between channels, chats, and topics in real-time. It supports one-to-one, many-to-one, and many-to-many mappings with per-direction filter pipelines. The system handles new messages, edits, deletions, and albums, and can operate with either an in-memory cache (backed by an LRU dict) or a PostgreSQL database for persisting message ID mappings. It includes a plugin-based filter system for message transformation (URL removal, keyword replacement, forward formatting, content skipping) and patches Telethon's sending functions to support topic replies. The application is designed to run as a long-lived service with a health endpoint for PaaS deployment (Heroku, Docker). The codebase is well-structured with clean separation of concerns, async-first design, and modern Python features (dataclasses, protocols, enums, pattern matching).