fix assistant streaming scroll lock

apps/docs/docs/management/assistant.mdx

@@ -22,6 +22,8 @@ While a response is running, a compact activity bar appears at the bottom of the
 avatar shows a thinking indicator. The activity bar can be opened to follow the response. Completed
 responses add an unread count to the user menu until they are opened or dismissed. The expanded
 conversation has a minimize action that returns it to the activity bar without interrupting a response.
+The transcript follows streamed output while it is already at the bottom, including fast responses. Scrolling
+up releases that follow state until **Scroll to latest** is selected or the user returns to the bottom.
 
 `Shift + A` opens the compact conversation panel directly. The shortcut is ignored while typing in text
 fields, selectors, and editable content.

apps/nextjs/src/components/assistant/assistant-panel.module.css

@@ -330,7 +330,6 @@
   flex: 1;
   flex-direction: column;
   overflow-y: auto;
-  scroll-behavior: smooth;
 }
 
 .messages {
@@ -1313,8 +1312,4 @@
     animation: none;
     transition: none;
   }
-
-  .viewport {
-    scroll-behavior: auto;
-  }
 }

apps/nextjs/src/components/assistant/assistant-panel.tsx

@@ -53,7 +53,7 @@ import {
   UnstyledButton,
   useCombobox,
 } from "@mantine/core";
-import { useWindowEvent } from "@mantine/hooks";
+import { useReducedMotion, useWindowEvent } from "@mantine/hooks";
 import {
   IconActivityHeartbeat,
   IconAlertTriangle,
@@ -2058,7 +2058,9 @@ export const AssistantConversationSurface = ({
   onMinimize,
 }: AssistantConversationSurfaceProps) => {
   const t = useScopedI18n("common.assistant");
+  const reducedMotion = useReducedMotion();
   const [questionPortalTarget, setQuestionPortalTarget] = useState<HTMLDivElement | null>(null);
+  const scrollToLatestBehavior = isRunning || reducedMotion ? "instant" : "smooth";
 
   return (
     <>
@@ -2122,7 +2124,7 @@ export const AssistantConversationSurface = ({
       </Group>
       <AssistantQuestionPortalProvider target={questionPortalTarget}>
         <ThreadPrimitive.Root className={classes.thread}>
-          <ThreadPrimitive.Viewport className={classes.viewport}>
+          <ThreadPrimitive.Viewport className={classes.viewport} autoScroll>
             <Box className={classes.messages}>
               <EmptyThread />
               <ThreadPrimitive.Messages components={{ UserMessage, AssistantMessage }} />
@@ -2134,7 +2136,7 @@ export const AssistantConversationSurface = ({
                 </Button>
               </SelectionToolbarPrimitive.Quote>
             </SelectionToolbarPrimitive.Root>
-            <ThreadPrimitive.ScrollToBottom asChild>
+            <ThreadPrimitive.ScrollToBottom behavior={scrollToLatestBehavior} asChild>
               <ActionIcon
                 className={classes.scrollToBottom}
                 variant="default"