Constant NOTICE_SIGNAL 

pub const NOTICE_SIGNAL: u8 = 0x84; // 132u8

Console-stream signal from a USB host: it has just printed a device notice (USB: WiFi dongle connected (xhci)) over whatever the console showed, and the program reading the console may want to put its own line back. The shell redraws its prompt with the half-typed line under the notice; anything else ignores it, because it is not a key. The hosts pushed a real Enter (\n) for this until 2026-10-24, and an Enter is an ANSWER: a plug while godspeed install asked [y/N] answered it N, and at the prompt it ran the half-typed line (the VisionFive card). Outside ASCII, so no typed key produces it, and read from here by both ends.