Stop auto scrolling when agent responds and let scroll area handle scrolling to bottom (#4257)

ui/desktop/src/components/BaseChat.tsx

@@ -42,7 +42,7 @@
  * while remaining flexible enough to support different UI contexts (Hub vs Pair).
  */
 
-import React, { useEffect, useContext, createContext, useRef, useCallback } from 'react';
+import React, { useEffect, useContext, createContext, useRef } from 'react';
 import { useLocation } from 'react-router-dom';
 import { SearchView } from './conversation/SearchView';
 import { AgentHeader } from './AgentHeader';
@@ -163,13 +163,6 @@ function BaseChatContent({
     chat,
     setChat,
     onMessageStreamFinish: () => {
-      // Auto-scroll to bottom when message stream finishes
-      setTimeout(() => {
-        if (scrollRef.current?.scrollToBottom) {
-          scrollRef.current.scrollToBottom();
-        }
-      }, 300);
-
       // Call the original callback if provided
       onMessageStreamFinish?.();
     },
@@ -303,11 +296,6 @@ function BaseChatContent({
           scrollRef.current.scrollToBottom();
         }
       }, 200);
-    } else {
-      // Immediate scroll for regular submit
-      if (scrollRef.current?.scrollToBottom) {
-        scrollRef.current.scrollToBottom();
-      }
     }
   };
 
@@ -319,18 +307,6 @@ function BaseChatContent({
     }
     append(text);
   };
-  // Callback to handle scroll to bottom from ProgressiveMessageList
-  const handleScrollToBottom = useCallback(() => {
-    // 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);
-    }
-  }, []);
 
   // Listen for global scroll-to-bottom requests (e.g., from MCP UI prompt actions)
   useEffect(() => {
@@ -433,7 +409,6 @@ function BaseChatContent({
                         setMessages(updatedMessages);
                       }}
                       isUserMessage={isUserMessage}
-                      onScrollToBottom={handleScrollToBottom}
                       isStreamingMessage={chatState !== ChatState.Idle}
                       onMessageUpdate={onMessageUpdate}
                     />
@@ -450,7 +425,6 @@ function BaseChatContent({
                           setMessages(updatedMessages);
                         }}
                         isUserMessage={isUserMessage}
-                        onScrollToBottom={handleScrollToBottom}
                         isStreamingMessage={chatState !== ChatState.Idle}
                         onMessageUpdate={onMessageUpdate}
                       />

ui/desktop/src/components/ProgressiveMessageList.tsx

@@ -30,7 +30,6 @@ interface ProgressiveMessageListProps {
   append?: (value: string) => void; // Make optional
   appendMessage?: (message: Message) => void; // Make optional
   isUserMessage: (message: Message) => boolean;
-  onScrollToBottom?: () => void;
   batchSize?: number;
   batchDelay?: number;
   showLoadingThreshold?: number; // Only show loading if more than X messages
@@ -47,7 +46,6 @@ export default function ProgressiveMessageList({
   append = () => {},
   appendMessage = () => {},
   isUserMessage,
-  onScrollToBottom,
   batchSize = 20,
   batchDelay = 20,
   showLoadingThreshold = 50,
@@ -99,10 +97,6 @@ export default function ProgressiveMessageList({
 
         if (nextCount >= messages.length) {
           setIsLoading(false);
-          // Trigger scroll to bottom
-          window.setTimeout(() => {
-            onScrollToBottom?.();
-          }, 100);
         } else {
           // Schedule next batch
           timeoutRef.current = window.setTimeout(loadNextBatch, batchDelay);
@@ -121,14 +115,7 @@ export default function ProgressiveMessageList({
         timeoutRef.current = null;
       }
     };
-  }, [
-    messages.length,
-    batchSize,
-    batchDelay,
-    showLoadingThreshold,
-    onScrollToBottom,
-    renderedCount,
-  ]);
+  }, [messages.length, batchSize, batchDelay, showLoadingThreshold, renderedCount]);
 
   // Cleanup on unmount
   useEffect(() => {
@@ -203,9 +190,6 @@ export default function ProgressiveMessageList({
                     chatId={chat.id}
                     workingDir={window.appConfig.get('GOOSE_WORKING_DIR') as string}
                     contextType={getContextHandlerType!(message)}
-                    onSummaryComplete={() => {
-                      window.setTimeout(() => onScrollToBottom?.(), 100);
-                    }}
                   />
                 ) : (
                   !hasOnlyToolResponses(message) && (
@@ -222,9 +206,6 @@ export default function ProgressiveMessageList({
                     chatId={chat.id}
                     workingDir={window.appConfig.get('GOOSE_WORKING_DIR') as string}
                     contextType={getContextHandlerType!(message)}
-                    onSummaryComplete={() => {
-                      window.setTimeout(() => onScrollToBottom?.(), 100);
-                    }}
                   />
                 ) : (
                   <GooseMessage
@@ -265,7 +246,6 @@ export default function ProgressiveMessageList({
     onMessageUpdate,
     hasContextHandlerContent,
     getContextHandlerType,
-    onScrollToBottom,
   ]);
 
   return (

ui/desktop/src/components/ui/scroll-area.tsx

@@ -67,17 +67,28 @@ const ScrollArea = React.forwardRef<ScrollAreaHandle, ScrollAreaProps>(
       const { scrollHeight, scrollTop, clientHeight } = viewport;
 
       const scrollBottom = scrollTop + clientHeight;
-      // Allow a small tolerance (2px) for rounding errors
-      const isAtBottom = scrollHeight - scrollBottom <= 2;
+      const isAtBottom = scrollHeight - scrollBottom <= 10;
 
       setIsFollowing(isAtBottom);
       setIsScrolled(scrollTop > 0);
     }, []);
 
-    React.useEffect(() => {
-      if (!autoScroll || !isFollowing) return;
+    // Track previous scroll height to detect content changes
+    const prevScrollHeightRef = React.useRef<number>(0);
 
-      scrollToBottom();
+    React.useEffect(() => {
+      if (!autoScroll || !isFollowing || !viewportRef.current) return;
+
+      const viewport = viewportRef.current;
+      const currentScrollHeight = viewport.scrollHeight;
+
+      // Only auto-scroll if content has actually grown (new content added)
+      // and we were already following (at the bottom)
+      if (currentScrollHeight > prevScrollHeightRef.current) {
+        scrollToBottom();
+      }
+
+      prevScrollHeightRef.current = currentScrollHeight;
     }, [children, autoScroll, isFollowing, scrollToBottom]);
 
     // Add scroll event listener