diff --git a/src/web-ui/src/flow_chat/components/modern/VirtualMessageList.tsx b/src/web-ui/src/flow_chat/components/modern/VirtualMessageList.tsx
index cf3c4476e..1b0e0c577 100644
--- a/src/web-ui/src/flow_chat/components/modern/VirtualMessageList.tsx
+++ b/src/web-ui/src/flow_chat/components/modern/VirtualMessageList.tsx
@@ -1553,15 +1553,15 @@ export const VirtualMessageList = forwardRef<VirtualMessageListRef>((_, ref) =>
   }, [activeSession, isProcessing]);
 
   const scrollToLatestEndPositionInternal = useCallback((behavior: 'auto' | 'smooth') => {
-    if (virtuosoRef.current && virtualItems.length > 0) {
+    const scroller = scrollerElementRef.current;
+    if (scroller) {
       clearAllBottomReservationsForUserNavigation();
-      virtuosoRef.current.scrollToIndex({
-        index: virtualItems.length - 1,
-        align: 'end',
+      scroller.scrollTo({
+        top: Math.max(0, scroller.scrollHeight - scroller.clientHeight),
         behavior,
       });
     }
-  }, [clearAllBottomReservationsForUserNavigation, virtualItems.length]);
+  }, [clearAllBottomReservationsForUserNavigation]);
 
   const requestTurnPinToTop = useCallback((turnId: string, options?: { behavior?: ScrollBehavior; pinMode?: FlowChatPinTurnToTopMode }) => {
     const requestedPinMode = options?.pinMode ?? 'transient';
@@ -1896,15 +1896,15 @@ export const VirtualMessageList = forwardRef<VirtualMessageListRef>((_, ref) =>
   });
 
   const scrollToPhysicalBottomAndClearPin = useCallback(() => {
-    if (virtuosoRef.current && virtualItems.length > 0) {
+    const scroller = scrollerElementRef.current;
+    if (scroller) {
       clearAllBottomReservationsForUserNavigation();
-      virtuosoRef.current.scrollToIndex({
-        index: virtualItems.length - 1,
-        align: 'end',
+      scroller.scrollTo({
+        top: Math.max(0, scroller.scrollHeight - scroller.clientHeight),
         behavior: 'smooth',
       });
     }
-  }, [clearAllBottomReservationsForUserNavigation, virtualItems.length]);
+  }, [clearAllBottomReservationsForUserNavigation]);
 
   const scrollToLatestEndPosition = useCallback(() => {
     enterFollowOutput('jump-to-latest');
diff --git a/src/web-ui/src/flow_chat/utils/flowChatScrollLayout.ts b/src/web-ui/src/flow_chat/utils/flowChatScrollLayout.ts
index e02e0c044..5ea2e7b7f 100644
--- a/src/web-ui/src/flow_chat/utils/flowChatScrollLayout.ts
+++ b/src/web-ui/src/flow_chat/utils/flowChatScrollLayout.ts
@@ -14,6 +14,7 @@ export const SCROLL_TO_LATEST_INPUT_CLEARANCE_PX = 6;
 
 const FALLBACK_INPUT_BLOCK_ACTIVE_PX = 96;
 const FALLBACK_INPUT_BLOCK_COLLAPSED_PX = 54;
+const NORMAL_INPUT_BLOCK_SAFE_PX = 96;
 
 /**
  * Height of the Virtuoso footer spacer needed so the last message clears the floating input.
@@ -23,11 +24,11 @@ export function computeFlowChatInputStackFooterPx(
   measuredInputHeight: number,
   isInputActive: boolean,
 ): number {
-  const inputBlock =
-    measuredInputHeight > 0
-      ? measuredInputHeight
-      : isInputActive
-        ? FALLBACK_INPUT_BLOCK_ACTIVE_PX
-        : FALLBACK_INPUT_BLOCK_COLLAPSED_PX;
+  const measuredInputBlock = measuredInputHeight > 0
+    ? measuredInputHeight
+    : isInputActive
+      ? FALLBACK_INPUT_BLOCK_ACTIVE_PX
+      : FALLBACK_INPUT_BLOCK_COLLAPSED_PX;
+  const inputBlock = Math.max(measuredInputBlock, NORMAL_INPUT_BLOCK_SAFE_PX);
   return inputBlock + CHAT_INPUT_DROP_ZONE_BOTTOM_PX + FLOWCHAT_MESSAGE_TAIL_CLEARANCE_PX;
 }