default_extract_turn_input

def default_extract_turn_input(envelope: Envelope) -> str | None:
    """Default ``extract_turn_input``: decode ``EV_TEXT`` only.

    Adapters that don't handle additional substantive event types
    delegate to this helper from their ``extract_turn_input``.
    """
    if envelope.event_type == EV_TEXT:
        text = envelope.event_data.get("text", "")
        return text if isinstance(text, str) else None
    return None