A generic, thread-safe LRU cache implementation using collections.OrderedDict. Supports capacity limits and configurable free factor for bulk eviction. Fully self-contained and can be extracted into any Python project needing a bounded cache with LRU semantics.

A URL matching utility that parses URLs using RFC 3986 regex and supports blacklist/whitelist filtering. Provides both exact match and substring search within text. Standalone and reusable for any URL filtering task (e.g., content moderation, link stripping).

Defines a generic filter pipeline protocol with MessageFilter, CompositeMessageFilter, and FilterAction enum. Supports sequential processing, early termination (DISCARD), and forced send (FORCE_SEND). The pattern is cleanly abstracted and could be reused for any sequential data transformation pipeline beyond Telegram messages.

Contains concrete filter implementations including ForwardFormatFilter (template-based message reformatting with channel name, link, sender info), KeywordReplaceFilter (regex-based keyword replacement with case-preserving logic), and URL/message skipping filters. The KeywordReplaceFilter's case-preserving replacement logic is non-trivial and demonstrates careful handling of text transformations.

Provides a clean Database protocol with two implementations: InMemoryDatabase (backed by LRUCache) and PostgresDatabase (using psycopg async connection pool). The abstraction allows swapping storage without changing business logic. The InMemoryDatabase uses a custom LRU cache for bounded memory usage, demonstrating practical caching in an async context.

Patches Telethon's send_message, forward_messages, and send_file to support the reply_to_topic_id parameter, which was missing from the library at the time. The patch carefully wraps the original functions while preserving all existing functionality. Demonstrates how to extend third-party async libraries without forking.