crates/rutster/tests/barge_in_integration.rs

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+// crates/rutster/tests/barge_in_integration.rs
+//
+// PRIMARY-path barge-in e2e proof (slice-4 spec §3.4, §6.1, §7 done-criteria #8).
+//
+// Constructs LocalVadReflex<Reflex<TapAudioPipe>> directly and proves that loud
+// caller audio kills playout within one tick, with only the local VAD as the
+// trigger source — no brain advisory is involved. This is wedge #1 from
+// README:98-100 and ARCHITECTURE.md:79-81.
+
+use rutster_media::{AudioSink, AudioSource, PcmFrame, VAD_DEBOUNCE_FRAMES};
+use rutster_media::{LocalVadReflex, Reflex, ReflexMetrics};
+use rutster_tap::{TapAudioPipe, TapMetrics};
+use tokio::sync::mpsc;
+
+#[tokio::test]
+async fn primary_path_local_vad_kills_playout_without_brain() {
+    let (tx_pcm_in, _rx_pcm_in) = mpsc::channel(32);
+    let (tx_audio_out, rx_audio_out) = mpsc::channel(32);
+    let tap_metrics = TapMetrics::new();
+    let pipe = TapAudioPipe::new(tx_pcm_in, rx_audio_out, tap_metrics);
+
+    let (advisory_tx, advisory_rx) = mpsc::channel(16);
+    let reflex_metrics = ReflexMetrics::new();
+    let reflex = Reflex::new(pipe, advisory_rx, reflex_metrics.clone());
+    let mut stack = LocalVadReflex::new(reflex, advisory_tx);
+
+    // Pre-load a brain audio_out frame into the ring (drain via next_pcm_frame).
+    tx_audio_out.send(PcmFrame::zeroed()).await.unwrap();
+    let _ = stack.next_pcm_frame(); // drain into ring
+    stack.next_pcm_frame(); // pop one (brain is playing)
+
+    // Loud caller audio × N → local VAD trips.
+    let mut loud = PcmFrame::zeroed();
+    for s in loud.samples.iter_mut() {
+        *s = 1000;
+    }
+    for _ in 0..VAD_DEBOUNCE_FRAMES {
+        stack.on_pcm_frame(loud.clone());
+    }
+
+    // Next playout tick: kill applied, None returned (ring cleared).
+    let f = stack.next_pcm_frame();
+    assert!(
+        f.is_none(),
+        "primary-path local VAD must kill playout within 1 tick"
+    );
+    assert_eq!(
+        reflex_metrics
+            .barge_in_count
+            .load(std::sync::atomic::Ordering::Relaxed),
+        1
+    );
+
+    // Fresh brain audio_out → resume.
+    tx_audio_out.send(PcmFrame::zeroed()).await.unwrap();
+    let resumed = stack.next_pcm_frame();
+    assert!(
+        resumed.is_some(),
+        "first fresh audio_out post-barge must resume playout"
+    );
+}