#[cfg(coverage)]
#[tonic::async_trait]
impl Relay for Handler {
    type StreamKeyboardStream = ReceiverStream<Result<KeyboardReport, Status>>;
    type StreamMouseStream = ReceiverStream<Result<MouseReport, Status>>;
    type CaptureVideoStream = VideoStream;
    type CaptureAudioStream = AudioStream;
    type StreamMicrophoneStream = ReceiverStream<Result<Empty, Status>>;
    type StreamCameraStream = ReceiverStream<Result<Empty, Status>>;

    async fn stream_keyboard(
        &self,
        req: Request<tonic::Streaming<KeyboardReport>>,
    ) -> Result<Response<Self::StreamKeyboardStream>, Status> {
        let (tx, rx) = tokio::sync::mpsc::channel(32);
        let kb = self.kb.clone();
        let report_delay = live_keyboard_report_delay();

        tokio::spawn(async move {
            let mut s = req.into_inner();
            while let Some(pkt) = s.next().await.transpose()? {
                let _ = runtime_support::write_hid_report(&kb, &hid_endpoint(0), &pkt.data).await;
                tx.send(Ok(pkt)).await.ok();
                if !report_delay.is_zero() {
                    #[cfg(not(coverage))]
                    tokio::time::sleep(report_delay).await;
                }
            }
            Ok::<(), Status>(())
        });

        Ok(Response::new(ReceiverStream::new(rx)))
    }

    async fn stream_mouse(
        &self,
        req: Request<tonic::Streaming<MouseReport>>,
    ) -> Result<Response<Self::StreamMouseStream>, Status> {
        let (tx, rx) = tokio::sync::mpsc::channel(32);
        let ms = self.ms.clone();

        tokio::spawn(async move {
            let mut s = req.into_inner();
            while let Some(pkt) = s.next().await.transpose()? {
                let _ = runtime_support::write_hid_report(&ms, &hid_endpoint(1), &pkt.data).await;
                tx.send(Ok(pkt)).await.ok();
            }
            Ok::<(), Status>(())
        });

        Ok(Response::new(ReceiverStream::new(rx)))
    }

    async fn stream_microphone(
        &self,
        req: Request<tonic::Streaming<AudioPacket>>,
    ) -> Result<Response<Self::StreamMicrophoneStream>, Status> {
        let lease = self.upstream_media_rt.activate_microphone();
        let Some(microphone_sink_permit) = self
            .upstream_media_rt
            .reserve_microphone_sink(lease.generation)
            .await
        else {
            return Err(Status::aborted(
                "microphone stream superseded before sink became available",
            ));
        };
        let uac_dev = std::env::var("LESAVKA_UAC_DEV").unwrap_or_else(|_| "hw:UAC2Gadget,0".into());
        let mut sink = runtime_support::open_voice_with_retry(&uac_dev)
            .await
            .map_err(|e| {
                self.upstream_media_rt.close_microphone(lease.generation);
                Status::internal(format!("{e:#}"))
            })?;
        let (tx, rx) = tokio::sync::mpsc::channel(1);
        let upstream_media_rt = self.upstream_media_rt.clone();

        tokio::spawn(async move {
            let _microphone_sink_permit = microphone_sink_permit;
            let mut inbound = req.into_inner();
            loop {
                if !upstream_media_rt.is_microphone_active(lease.generation) {
                    break;
                }
                let next_packet = tokio::select! {
                    packet = inbound.next() => packet,
                    _ = tokio::time::sleep(Duration::from_millis(25)) => continue,
                };
                let Some(mut pkt) = next_packet.transpose()? else {
                    break;
                };
                let plan = upstream_media_rt.plan_audio_pts(pkt.pts);
                tokio::time::sleep_until(plan.due_at).await;
                pkt.pts = plan.local_pts_us;
                sink.push(&pkt);
            }
            sink.finish();
            upstream_media_rt.close_microphone(lease.generation);
            let _ = tx.send(Ok(Empty {})).await;
            Ok::<(), Status>(())
        });

        Ok(Response::new(ReceiverStream::new(rx)))
    }

    async fn stream_camera(
        &self,
        req: Request<tonic::Streaming<VideoPacket>>,
    ) -> Result<Response<Self::StreamCameraStream>, Status> {
        let cfg = camera::current_camera_config();
        let upstream_lease = self.upstream_media_rt.activate_camera();
        let (session_id, relay) = self.camera_rt.activate(&cfg).await?;
        let camera_rt = self.camera_rt.clone();
        let upstream_media_rt = self.upstream_media_rt.clone();
        let (tx, rx) = tokio::sync::mpsc::channel(1);
        let frame_step_us = (1_000_000u64 / u64::from(cfg.fps.max(1))).max(1);

        tokio::spawn(async move {
            let mut s = req.into_inner();
            loop {
                if !camera_rt.is_active(session_id)
                    || !upstream_media_rt.is_camera_active(upstream_lease.generation)
                {
                    break;
                }
                let next_packet = tokio::select! {
                    packet = s.next() => packet,
                    _ = tokio::time::sleep(Duration::from_millis(25)) => continue,
                };
                let Some(mut pkt) = next_packet.transpose()? else {
                    break;
                };
                let plan = upstream_media_rt.plan_video_pts(pkt.pts, frame_step_us);
                tokio::time::sleep_until(plan.due_at).await;
                pkt.pts = plan.local_pts_us;
                relay.feed(pkt);
            }
            upstream_media_rt.close_camera(upstream_lease.generation);
            tx.send(Ok(Empty {})).await.ok();
            Ok::<(), Status>(())
        });

        Ok(Response::new(ReceiverStream::new(rx)))
    }

    async fn capture_video(
        &self,
        req: Request<MonitorRequest>,
    ) -> Result<Response<Self::CaptureVideoStream>, Status> {
        self.capture_video_reply(req.into_inner()).await
    }

    async fn capture_audio(
        &self,
        _req: Request<MonitorRequest>,
    ) -> Result<Response<Self::CaptureAudioStream>, Status> {
        Err(Status::internal(
            "audio capture unavailable in coverage harness",
        ))
    }

    async fn paste_text(&self, req: Request<PasteRequest>) -> Result<Response<PasteReply>, Status> {
        self.paste_text_reply(req).await
    }

    async fn reset_usb(&self, _req: Request<Empty>) -> Result<Response<ResetUsbReply>, Status> {
        self.reset_usb_reply().await
    }

    async fn get_capture_power(
        &self,
        _req: Request<Empty>,
    ) -> Result<Response<CapturePowerState>, Status> {
        self.get_capture_power_reply().await
    }

    async fn set_capture_power(
        &self,
        req: Request<SetCapturePowerRequest>,
    ) -> Result<Response<CapturePowerState>, Status> {
        self.set_capture_power_reply(req).await
    }
}