Constant FORWARDING_RETIRED_NOTICE 

pub const FORWARDING_RETIRED_NOTICE: &[u8] = b"HERMIT_DETLOG_RECORD_LOST 0 0 socket retired\n";

The message an in-guest runtime sends on the forwarding socket when it has to give the socket up (reverie-liteinst’s reserve_tool_output_fd retirement message): a FORWARDING_LOSS_NOTICE, since no later record can arrive.