Function fan_out_voice_at 

pub async fn fan_out_voice_at<P: Protocol>(
    socket: &UdpSocket,
    clients: &ClientPool<P>,
    from: SocketAddr,
    module: Module,
    bytes: &[u8],
    now: Instant,
) -> Result<FanOutReport, ShellError>

Same as fan_out_voice, but takes an injected now: Instant for deterministic rate-limiter testing.

Production callers use fan_out_voice which samples the wall clock itself; tests can drive this variant to advance the token bucket’s refill clock without waiting for real time.

Errors

Same as fan_out_voice: reserved for future fatal conditions.