default_render_envelope

def default_render_envelope(envelope: Envelope) -> str | None:
    """Default ``render_envelope``: project ``EV_TEXT`` only.

    Returns the envelope's text payload, or ``None`` for any other
    event type (so the view skips it). Adapters that emit additional
    substantive event types override ``render_envelope`` and fall
    through to this helper for ``EV_TEXT``.
    """
    if envelope.event_type == EV_TEXT:
        text = envelope.event_data.get("text", "")
        return text if isinstance(text, str) else None
    return None