Fix slow typing in chat input with long running sessions (#3722)

ui/desktop/src/components/BaseChat.tsx

@@ -313,11 +313,15 @@ function BaseChatContent({
   };
   // Callback to handle scroll to bottom from ProgressiveMessageList
   const handleScrollToBottom = useCallback(() => {
-    setTimeout(() => {
-      if (scrollRef.current?.scrollToBottom) {
-        scrollRef.current.scrollToBottom();
-      }
-    }, 100);
+    // Only auto-scroll if user is not actively typing
+    const isUserTyping = document.activeElement?.id === 'dynamic-textarea';
+    if (!isUserTyping) {
+      setTimeout(() => {
+        if (scrollRef.current?.scrollToBottom) {
+          scrollRef.current.scrollToBottom();
+        }
+      }, 100);
+    }
   }, []);
 
   return (

ui/desktop/src/components/ChatInput.tsx

@@ -239,6 +239,7 @@ export default function ChatInput({
   const [isInGlobalHistory, setIsInGlobalHistory] = useState(false);
   const [hasUserTyped, setHasUserTyped] = useState(false);
   const textAreaRef = useRef<HTMLTextAreaElement>(null);
+  const timeoutRefsRef = useRef<Set<ReturnType<typeof setTimeout>>>(new Set());
 
   // Use shared file drop hook for ChatInput
   const {
@@ -441,25 +442,50 @@ export default function ChatInput({
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [numTokens, toolCount, tokenLimit, isTokenLimitLoaded, addAlert, clearAlerts]);
 
+  // Cleanup effect for component unmount - prevent memory leaks
+  useEffect(() => {
+    return () => {
+      // Clear any pending timeouts from image processing
+      setPastedImages((currentImages) => {
+        currentImages.forEach((img) => {
+          if (img.filePath) {
+            try {
+              window.electron.deleteTempFile(img.filePath);
+            } catch (error) {
+              console.error('Error deleting temp file:', error);
+            }
+          }
+        });
+        return [];
+      });
+
+      // Clear all tracked timeouts
+      // eslint-disable-next-line react-hooks/exhaustive-deps
+      const timeouts = timeoutRefsRef.current;
+      timeouts.forEach((timeoutId) => {
+        window.clearTimeout(timeoutId);
+      });
+      timeouts.clear();
+
+      // Clear alerts to prevent memory leaks
+      clearAlerts();
+    };
+  }, [clearAlerts]);
+
   const maxHeight = 10 * 24;
 
-  // Debounced function to update actual value
-  const debouncedSetValue = useMemo(
-    () =>
-      debounce((value: string) => {
-        setValue(value);
-      }, 150),
-    [setValue]
-  );
+  // Immediate function to update actual value - no debounce for better responsiveness
+  const updateValue = React.useCallback((value: string) => {
+    setValue(value);
+  }, []);
 
-  // Debounced autosize function
   const debouncedAutosize = useMemo(
     () =>
       debounce((element: HTMLTextAreaElement) => {
         element.style.height = '0px'; // Reset height
         const scrollHeight = element.scrollHeight;
         element.style.height = Math.min(scrollHeight, maxHeight) + 'px';
-      }, 150),
+      }, 50),
     [maxHeight]
   );
 
@@ -481,7 +507,7 @@ export default function ChatInput({
     const cursorPosition = evt.target.selectionStart;
 
     setDisplayValue(val); // Update display immediately
-    debouncedSetValue(val); // Debounce the actual state update
+    updateValue(val); // Update actual value immediately for better responsiveness
     debouncedSaveDraft(val); // Save draft with debounce
     // Mark that the user has typed something
     setHasUserTyped(true);
@@ -544,10 +570,12 @@ export default function ChatInput({
         },
       ]);
 
-      // Remove the error message after 5 seconds
-      setTimeout(() => {
+      // Remove the error message after 5 seconds with cleanup tracking
+      const timeoutId = setTimeout(() => {
         setPastedImages((prev) => prev.filter((img) => !img.id.startsWith('error-')));
+        timeoutRefsRef.current.delete(timeoutId);
       }, 5000);
+      timeoutRefsRef.current.add(timeoutId);
 
       return;
     }
@@ -568,10 +596,12 @@ export default function ChatInput({
           error: `Image too large (${Math.round(file.size / (1024 * 1024))}MB). Maximum ${MAX_IMAGE_SIZE_MB}MB allowed.`,
         });
 
-        // Remove the error message after 5 seconds
-        setTimeout(() => {
+        // Remove the error message after 5 seconds with cleanup tracking
+        const timeoutId = setTimeout(() => {
           setPastedImages((prev) => prev.filter((img) => img.id !== errorId));
+          timeoutRefsRef.current.delete(timeoutId);
         }, 5000);
+        timeoutRefsRef.current.add(timeoutId);
 
         continue;
       }
@@ -636,11 +666,10 @@ export default function ChatInput({
   // Cleanup debounced functions on unmount
   useEffect(() => {
     return () => {
-      debouncedSetValue.cancel?.();
       debouncedAutosize.cancel?.();
       debouncedSaveDraft.cancel?.();
     };
-  }, [debouncedSetValue, debouncedAutosize, debouncedSaveDraft]);
+  }, [debouncedAutosize, debouncedSaveDraft]);
 
   // Handlers for composition events, which are crucial for proper IME behavior
   const handleCompositionStart = () => {

ui/desktop/src/components/ProgressiveMessageList.tsx

@@ -47,9 +47,9 @@ export default function ProgressiveMessageList({
   appendMessage = () => {},
   isUserMessage,
   onScrollToBottom,
-  batchSize = 15, // Render 15 messages per batch (reduced for better UX)
-  batchDelay = 30, // 30ms delay between batches (faster)
-  showLoadingThreshold = 30, // Only show progressive loading for 30+ messages (lower threshold)
+  batchSize = 20,
+  batchDelay = 20,
+  showLoadingThreshold = 50,
   renderMessage, // Custom render function
   isStreamingMessage = false, // Whether messages are currently being streamed
 }: ProgressiveMessageListProps) {

ui/desktop/src/hooks/useFileDrop.ts

@@ -1,4 +1,4 @@
-import { useCallback, useState } from 'react';
+import { useCallback, useState, useRef, useEffect } from 'react';
 
 export interface DroppedFile {
   id: string;
@@ -13,6 +13,24 @@ export interface DroppedFile {
 
 export const useFileDrop = () => {
   const [droppedFiles, setDroppedFiles] = useState<DroppedFile[]>([]);
+  const activeReadersRef = useRef<Set<FileReader>>(new Set());
+
+  // Cleanup effect to prevent memory leaks
+  useEffect(() => {
+    return () => {
+      // Abort any active FileReaders on unmount
+      // eslint-disable-next-line react-hooks/exhaustive-deps
+      const readers = activeReadersRef.current;
+      readers.forEach((reader) => {
+        try {
+          reader.abort();
+        } catch (error) {
+          // Reader might already be done, ignore errors
+        }
+      });
+      readers.clear();
+    };
+  }, []);
 
   const handleDrop = useCallback(async (e: React.DragEvent<HTMLDivElement>) => {
     e.preventDefault();
@@ -56,12 +74,16 @@ export const useFileDrop = () => {
         // For images, generate a preview (only if successfully processed)
         if (droppedFile.isImage && !droppedFile.error) {
           const reader = new FileReader();
+          activeReadersRef.current.add(reader);
+
           reader.onload = (event) => {
             const dataUrl = event.target?.result as string;
             setDroppedFiles((prev) =>
               prev.map((f) => (f.id === droppedFile.id ? { ...f, dataUrl, isLoading: false } : f))
             );
+            activeReadersRef.current.delete(reader);
           };
+
           reader.onerror = () => {
             console.error('Failed to generate preview for:', file.name);
             setDroppedFiles((prev) =>
@@ -71,7 +93,13 @@ export const useFileDrop = () => {
                   : f
               )
             );
+            activeReadersRef.current.delete(reader);
           };
+
+          reader.onabort = () => {
+            activeReadersRef.current.delete(reader);
+          };
+
           reader.readAsDataURL(file);
         }
       }

ui/desktop/src/hooks/useWhisper.ts

@@ -199,13 +199,29 @@ export const useWhisper = ({ onTranscription, onError, onSizeWarning }: UseWhisp
     }
 
     // Close audio context
-    if (audioContext) {
-      audioContext.close();
+    if (audioContext && audioContext.state !== 'closed') {
+      audioContext.close().catch(console.error);
       setAudioContext(null);
       setAnalyser(null);
     }
   }, [audioContext]);
 
+  // Cleanup effect to prevent memory leaks
+  useEffect(() => {
+    return () => {
+      // Cleanup on unmount
+      if (durationIntervalRef.current) {
+        clearInterval(durationIntervalRef.current);
+      }
+      if (streamRef.current) {
+        streamRef.current.getTracks().forEach((track) => track.stop());
+      }
+      if (audioContext && audioContext.state !== 'closed') {
+        audioContext.close().catch(console.error);
+      }
+    };
+  }, [audioContext]);
+
   const startRecording = useCallback(async () => {
     if (!dictationSettings) {
       onError?.(new Error('Dictation settings not loaded'));