Function session_frame_to_frame 

pub fn session_frame_to_frame(frame: &SessionFrame, seq: u64) -> Frame

Wrap one SessionFrame in a SESSION-lane Frame.

The envelope carries the v1 defaults (envelope_version, payload_encoding = NONE, no deadline, empty trace context) from Frame::request, with payload_protocol pinned to SESSION_PAYLOAD_PROTOCOL, request_id set to the session-local seq, and kind derived from the frame’s direction. A SessionFrame with no kind set (an empty oneof — never produced by the pump) defaults to REQUEST; it still round-trips, carrying an empty payload.