Provides a reusable SQLite mixin class that implements common CRUD operations and schema management for news and RSS data. It encapsulates connection handling, batch operations, schema migration (e.g., adding guid column), and row-count queries. Both LocalStorageBackend and RemoteStorageBackend inherit from this mixin, demonstrating a clean template-method pattern that isolates SQL logic from storage backend specifics. This component is self-contained and could be extracted to provide a generic SQLite data access layer for any project requiring structured storage with minimal overhead.

Implements a byte-aware text splitter for push notifications that respects per-channel message size limits. It uses `_split_text_into_batches` to break long messages at line boundaries while preserving truncation markers and footers (e.g., '...' placeholders). The component handles overlapping start/end markers ('<<', '>>') and per-platform max-byte configurations, ensuring no message exceeds the channel's allowed payload size. This is highly reusable in any multi-channel notification system where message content varies in length and channels impose hard byte limits, and it demonstrates careful consideration of edge cases in text segmentation.

Implements a resilient multi-source content fetcher that attempts to download from a prioritized list of CDN or direct URLs, caching the last successful source in session memory for subsequent requests. It uses `urllib.request` with proper error handling, timeout, and a fallback chain (e.g., `url1 → url2 → url3`). The `get_content` function returns the first successful response, and `get_cdn_content` adds a session-level cache of the winning source to avoid re-probing on every call. This pattern is directly usable in any project needing robust resource fetching from multiple mirrors, such as version checks, asset downloads, or config updates from distributed origins.