feat: Cancel streaming LLM when user sends new message

- Add active_streams HashMap to AppState to track streaming sessions
- Create cancellation channel for each streaming session
- Cancel existing streaming when new message arrives
- Prevents overlapping responses and improves UX

src/core/bot/mod.rs

@@ -825,18 +825,29 @@ impl BotOrchestrator {
         // #[cfg(feature = "drive")]
         // set_llm_streaming(true);
 
-        let stream_tx_clone = stream_tx.clone();
-        tokio::spawn(async move {
-            if let Err(e) = llm
-                .generate_stream("", &messages_clone, stream_tx_clone, &model_clone, &key_clone, tools_for_llm.as_ref())
-                .await
-            {
-                error!("LLM streaming error: {}", e);
-            }
-            // REMOVED: LLM streaming lock was causing deadlocks
-            // #[cfg(feature = "drive")]
-            // set_llm_streaming(false);
-        });
+    let stream_tx_clone = stream_tx.clone();
+    
+    // Create cancellation channel for this streaming session
+    let (cancel_tx, mut cancel_rx) = mpsc::channel::<()>(1);
+    let session_id_str = session.id.to_string();
+    
+    // Register this streaming session for potential cancellation
+    {
+        let mut active_streams = self.state.active_streams.lock().await;
+        active_streams.insert(session_id_str.clone(), cancel_tx);
+    }
+    
+    tokio::spawn(async move {
+        if let Err(e) = llm
+        .generate_stream("", &messages_clone, stream_tx_clone, &model_clone, &key_clone, tools_for_llm.as_ref())
+        .await
+        {
+            error!("LLM streaming error: {}", e);
+        }
+        // REMOVED: LLM streaming lock was causing deadlocks
+        // #[cfg(feature = "drive")]
+        // set_llm_streaming(false);
+    });
 
         let mut full_response = String::new();
         let mut analysis_buffer = String::new();
@@ -872,11 +883,17 @@ impl BotOrchestrator {
             }
         }
 
-        while let Some(chunk) = stream_rx.recv().await {
-            chunk_count += 1;
-            if chunk_count <= 3 || chunk_count % 50 == 0 {
-                info!("LLM chunk #{chunk_count} received for session {} (len={})", session.id, chunk.len());
-            }
+    while let Some(chunk) = stream_rx.recv().await {
+        // Check if cancellation was requested (user sent new message)
+        if cancel_rx.try_recv().is_ok() {
+            info!("Streaming cancelled for session {} - user sent new message", session.id);
+            break;
+        }
+        
+        chunk_count += 1;
+        if chunk_count <= 3 || chunk_count % 50 == 0 {
+            info!("LLM chunk #{chunk_count} received for session {} (len={})", session.id, chunk.len());
+        }
 
             // ===== GENERIC TOOL EXECUTION =====
             // Add chunk to tool_call_buffer and try to parse
@@ -1718,25 +1735,37 @@ let mut send_task = tokio::spawn(async move {
                         };
 
                         if let Some(tx_clone) = tx_opt {
-                            let corrected_msg = UserMessage {
-                                bot_id: bot_id.to_string(),
-                                user_id: session.user_id.to_string(),
-                                session_id: session.id.to_string(),
-                                ..user_msg
-                            };
-                            info!("Calling orchestrator for session {}", session_id);
+                    // CANCEL any existing streaming for this session first
+                    let session_id_str = session_id.to_string();
+                    {
+                        let mut active_streams = state_clone.active_streams.lock().await;
+                        if let Some(cancel_tx) = active_streams.remove(&session_id_str) {
+                            info!("Cancelling existing streaming for session {}", session_id);
+                            let _ = cancel_tx.send(()).await;
+                            // Give a moment for the streaming to stop
+                            tokio::time::sleep(tokio::time::Duration::from_millis(50)).await;
+                        }
+                    }
+                    
+                    let corrected_msg = UserMessage {
+                        bot_id: bot_id.to_string(),
+                        user_id: session.user_id.to_string(),
+                        session_id: session.id.to_string(),
+                        ..user_msg
+                    };
+                    info!("Calling orchestrator for session {}", session_id);
 
-                            // Spawn LLM in its own task so recv_task stays free to handle
-                            // new messages — prevents one hung LLM from locking the session.
-                            let orch = BotOrchestrator::new(state_clone.clone());
-                            tokio::spawn(async move {
-                                if let Err(e) = orch
-                                    .stream_response(corrected_msg, tx_clone)
-                                    .await
-                                {
-                                    error!("Failed to stream response: {}", e);
-                                }
-                            });
+                    // Spawn LLM in its own task so recv_task stays free to handle
+                    // new messages — prevents one hung LLM from locking the session.
+                    let orch = BotOrchestrator::new(state_clone.clone());
+                    tokio::spawn(async move {
+                        if let Err(e) = orch
+                        .stream_response(corrected_msg, tx_clone)
+                        .await
+                        {
+                            error!("Failed to stream response: {}", e);
+                        }
+                    });
                         } else {
                             warn!("Response channel NOT found for session: {}", session_id);
                         }

src/core/shared/state.rs

@@ -398,6 +398,8 @@ pub struct AppState {
     pub auth_service: Arc<tokio::sync::Mutex<AuthService>>,
     pub channels: Arc<tokio::sync::Mutex<HashMap<String, Arc<dyn ChannelAdapter>>>>,
     pub response_channels: Arc<tokio::sync::Mutex<HashMap<String, mpsc::Sender<BotResponse>>>>,
+    /// Active streaming sessions for cancellation: session_id → cancellation sender
+    pub active_streams: Arc<tokio::sync::Mutex<HashMap<String, mpsc::Sender<()>>>>,
     /// Blocking channels for HEAR: session_id → sender. Rhai thread blocks on receiver.
     pub hear_channels: Arc<std::sync::Mutex<HashMap<uuid::Uuid, std::sync::mpsc::SyncSender<String>>>>,
     pub web_adapter: Arc<WebChannelAdapter>,
@@ -450,6 +452,7 @@ impl Clone for AppState {
             kb_manager: self.kb_manager.clone(),
             channels: Arc::clone(&self.channels),
             response_channels: Arc::clone(&self.response_channels),
+            active_streams: Arc::clone(&self.active_streams),
             hear_channels: Arc::clone(&self.hear_channels),
             web_adapter: Arc::clone(&self.web_adapter),
             voice_adapter: Arc::clone(&self.voice_adapter),
@@ -665,6 +668,7 @@ impl Default for AppState {
             auth_service: Arc::new(tokio::sync::Mutex::new(create_mock_auth_service())),
             channels: Arc::new(tokio::sync::Mutex::new(HashMap::new())),
             response_channels: Arc::new(tokio::sync::Mutex::new(HashMap::new())),
+            active_streams: Arc::new(tokio::sync::Mutex::new(HashMap::new())),
             hear_channels: Arc::new(std::sync::Mutex::new(HashMap::new())),
             web_adapter: Arc::new(WebChannelAdapter::new()),
             voice_adapter: Arc::new(VoiceAdapter::new()),

src/main_module/bootstrap.rs

@@ -606,16 +606,17 @@ pub async fn create_app_state(
         dynamic_llm_provider: Some(dynamic_llm_provider.clone()),
         #[cfg(feature = "directory")]
         auth_service: auth_service.clone(),
-        channels: Arc::new(tokio::sync::Mutex::new({
-            let mut map = HashMap::new();
-            map.insert(
-                "web".to_string(),
-                web_adapter.clone() as Arc<dyn crate::core::bot::channels::ChannelAdapter>,
-            );
-            map
-        })),
-        response_channels: Arc::new(tokio::sync::Mutex::new(HashMap::new())),
-        hear_channels: Arc::new(std::sync::Mutex::new(HashMap::new())),
+            channels: Arc::new(tokio::sync::Mutex::new({
+                let mut map = HashMap::new();
+                map.insert(
+                    "web".to_string(),
+                    web_adapter.clone() as Arc<dyn crate::core::bot::channels::ChannelAdapter>,
+                );
+                map
+            })),
+            response_channels: Arc::new(tokio::sync::Mutex::new(HashMap::new())),
+            active_streams: Arc::new(tokio::sync::Mutex::new(HashMap::new())),
+            hear_channels: Arc::new(std::sync::Mutex::new(HashMap::new())),
         web_adapter: web_adapter.clone(),
         voice_adapter: voice_adapter.clone(),
         #[cfg(any(feature = "research", feature = "llm"))]