Function relay_device_session 

pub fn relay_device_session<R: BufRead, W: Write>(
    reader: R,
    writer: W,
    device: &str,
    platform: &str,
    token: &str,
    injector: &dyn Injector,
) -> Result<SessionEnd, AppError>

Register to a relay as a DEVICE over reader/writer, then drain bare InjectionCommand lines, replaying each via injector. One pass over a connected stream (no reconnect); returns how the session ended.

Errors

AppError::internal on a write/read I/O error.