The /help command was routed through _forward_command → _handle_message
→ is_allowed(), which denied access to users not in the allowFrom list.
Since /help is purely informational, it should be accessible to all
users — similar to how /start already works with its own handler.
Add a dedicated _on_help handler that replies directly without going
through the message bus access control.
Closes#687
- Added _split_message() helper for cleaner separation of concerns
- Simplified send() method by using the helper
- Net -18 lines for the message splitting feature
Telegram has a 4096 character limit per message. This fix:
- Splits messages longer than 4000 chars into multiple chunks
- Prefers breaking at newline boundaries to preserve formatting
- Falls back to space boundaries if no newlines available
- Forces split at max length if no good boundaries exist
- Adds comprehensive tests for message splitting logic
- Update sender ID construction to prioritize user ID while maintaining username for allowlist compatibility.
- Improve allowlist checking in BaseChannel to support sender IDs with multiple parts separated by '|'.
