Introduce `cached_get_chat` in `tg_cache` to store channel metadata on disk with a configurable TTL (default 12 hours). Use the `tg_rpc` throttling context for RPC calls. Update `rss_generator` to use the cached version and document related environment variables in `dockercompose.yml`.
Convert delayed_delete_file to async and use asyncio.sleep.
Add pre‑semaphore cache hit to serve cached files without acquiring the download semaphore.
Set SQLite busy_timeout to reduce lock errors.
Introduce a diagnostics counter for pending _persist_media_file_id_async tasks.
Refactor flag extraction to accept pre‑generated HTML and compute html body once.
Batch reply enrichment in RSS generator to minimize API calls.
Store cached messages directly in tg_cache and add fallback for legacy double‑pickle format.
BREAKING CHANGE: delayed_delete_file is now async and must be awaited.
vvzvlad