diff --git a/web/pages/Assistants.tsx b/web/pages/Assistants.tsx
index b1dea9e..9c9be45 100644
--- a/web/pages/Assistants.tsx
+++ b/web/pages/Assistants.tsx
@@ -1065,6 +1065,7 @@ export const DebugDrawer: React.FC<{
   const assistantDraftIndexRef = useRef<number | null>(null);
   const audioCtxRef = useRef<AudioContext | null>(null);
   const playbackTimeRef = useRef<number>(0);
+  const activeAudioSourcesRef = useRef<Set<AudioBufferSourceNode>>(new Set());
 
   const [devices, setDevices] = useState<MediaDeviceInfo[]>([]);
   const [selectedCamera, setSelectedCamera] = useState<string>('');
@@ -1151,6 +1152,19 @@ export const DebugDrawer: React.FC<{
     playbackTimeRef.current = ctx.currentTime;
   };
 
+  const stopPlaybackImmediately = () => {
+    activeAudioSourcesRef.current.forEach((source) => {
+      try {
+        source.stop();
+      } catch {
+        // no-op
+      }
+      source.disconnect();
+    });
+    activeAudioSourcesRef.current.clear();
+    clearPlaybackQueue();
+  };
+
   const playPcm16Chunk = async (pcmBuffer: ArrayBuffer) => {
     if (!textTtsEnabled) return;
     if (mode !== 'text') return;
@@ -1170,6 +1184,15 @@ export const DebugDrawer: React.FC<{
     const source = ctx.createBufferSource();
     source.buffer = audioBuffer;
     source.connect(ctx.destination);
+    activeAudioSourcesRef.current.add(source);
+    source.onended = () => {
+      activeAudioSourcesRef.current.delete(source);
+      try {
+        source.disconnect();
+      } catch {
+        // no-op
+      }
+    };
 
     const startAt = Math.max(ctx.currentTime + 0.02, playbackTimeRef.current);
     source.start(startAt);
@@ -1228,6 +1251,11 @@ export const DebugDrawer: React.FC<{
       if (mode === 'text') {
         if (textTtsEnabled) await ensureAudioContext();
         await ensureWsSession();
+        // Interrupt any in-flight response/audio before sending new user utterance.
+        if (wsRef.current?.readyState === WebSocket.OPEN) {
+          wsRef.current.send(JSON.stringify({ type: 'response.cancel', graceful: false }));
+        }
+        stopPlaybackImmediately();
         wsRef.current?.send(JSON.stringify({ type: 'input.text', text: userMsg }));
       } else {
         setTimeout(() => {
@@ -1391,7 +1419,7 @@ export const DebugDrawer: React.FC<{
     pendingRejectRef.current = null;
     assistantDraftIndexRef.current = null;
     setTextSessionStarted(false);
-    clearPlaybackQueue();
+    stopPlaybackImmediately();
     if (isOpen) setWsStatus('disconnected');
   };
 
@@ -1456,7 +1484,15 @@ export const DebugDrawer: React.FC<{
           return;
         }
         if (type === 'output.audio.start') {
-          clearPlaybackQueue();
+          // New utterance audio starts: cancel old queued/playing audio to avoid overlap.
+          stopPlaybackImmediately();
+          return;
+        }
+
+        if (type === 'response.interrupted') {
+          assistantDraftIndexRef.current = null;
+          setIsLoading(false);
+          stopPlaybackImmediately();
           return;
         }
 
@@ -1541,7 +1577,7 @@ export const DebugDrawer: React.FC<{
       ws.onclose = () => {
         wsReadyRef.current = false;
         setTextSessionStarted(false);
-        clearPlaybackQueue();
+        stopPlaybackImmediately();
         if (wsStatus !== 'error') setWsStatus('disconnected');
       };
     });
@@ -1549,7 +1585,7 @@ export const DebugDrawer: React.FC<{
 
   useEffect(() => {
     if (!textTtsEnabled) {
-      clearPlaybackQueue();
+      stopPlaybackImmediately();
     }
   }, [textTtsEnabled]);
 
@@ -1660,13 +1696,10 @@ export const DebugDrawer: React.FC<{
             <div className="flex-1 overflow-hidden flex flex-col min-h-0 mb-4">
               {mode === 'text' ? (
                 textSessionStarted ? (
-                  <div className="flex-1 flex flex-col min-h-0 space-y-2">
-                    <div className="flex flex-col h-full animate-in fade-in">
+                  <div className="flex-1 flex flex-col min-h-0 animate-in fade-in">
+                    <div className="h-[52vh] min-h-[260px] max-h-[52vh]">
                       <TranscriptionLog />
                     </div>
-                    <Button variant="destructive" size="sm" className="w-full h-10 font-bold" onClick={closeWs}>
-                      <PhoneOff className="mr-2 h-4 w-4" /> 结束测试
-                    </Button>
                   </div>
                 ) : wsStatus === 'connecting' ? (
                   <div className="flex-1 flex flex-col items-center justify-center space-y-6">
@@ -1769,6 +1802,11 @@ export const DebugDrawer: React.FC<{
 
             <div className="shrink-0 space-y-2">
               <div className="flex space-x-2">
+                {mode === 'text' && textSessionStarted && (
+                  <Button variant="destructive" size="sm" className="h-9 font-bold shrink-0" onClick={closeWs}>
+                    <PhoneOff className="mr-2 h-4 w-4" /> 结束测试
+                  </Button>
+                )}
                 <Input
                   value={inputText}
                   onChange={e => setInputText(e.target.value)}