Fix task conversation scroll reset

desktop/src/features/agents/ui/AgentConversationScreen.tsx

@@ -811,10 +811,10 @@ export function AgentConversationScreen({
         emptyTitle="No conversation messages yet"
         hasComposerOverlay
         isLoading={messagesQuery.isLoading && timelineMessages.length === 0}
-        layoutShiftKey={conversation.id}
         messageListPlacement="top"
         messages={timelineMessages}
         profiles={profiles}
+        scrollResetKey={conversation.id}
         scrollContainerRef={timelineScrollRef}
         showInitialDayDivider={false}
         trailingContent={

desktop/src/features/channels/ui/ChannelPane.tsx

@@ -794,7 +794,6 @@ export const ChannelPane = React.memo(function ChannelPane({
                 hasComposerOverlay={hasMainComposerOverlay}
                 hasOlderMessages={hasOlderMessages}
                 isFetchingOlder={isFetchingOlder}
-                layoutShiftKey={useSplitAuxiliaryPane ? "split" : "overlay"}
                 isFollowingThreadById={isFollowingThreadById}
                 isMessageUnreadById={isMessageUnreadById}
                 personaLookup={personaLookup}

desktop/src/features/messages/ui/MessageTimeline.tsx

@@ -56,7 +56,7 @@ type MessageTimelineProps = {
   hasComposerOverlay?: boolean;
   contentTopPadding?: "chrome" | "compact";
   isFetchingOlder?: boolean;
-  layoutShiftKey?: string | number | null;
+  scrollResetKey?: string | number | null;
   messageListPlacement?: "bottom" | "top";
   messageFooters?: Record<string, React.ReactNode>;
   /** Map from lowercase pubkey → persona display name for bot members. */
@@ -164,7 +164,7 @@ const MessageTimelineBase = React.forwardRef<
     contentTopPadding = "chrome",
     hasOlderMessages = true,
     isFetchingOlder = false,
-    layoutShiftKey = null,
+    scrollResetKey = null,
     messageListPlacement = "bottom",
     followThreadById,
     huddleMemberPubkeys,
@@ -233,16 +233,15 @@ const MessageTimelineBase = React.forwardRef<
     liveSnapshot,
   });
   const isRenderPending = deferredSnapshot !== liveSnapshot;
-  const scrollRouteKey = `${channelId ?? "none"}:${layoutShiftKey ?? "none"}`;
+  const scrollIdentityKey = `${channelId ?? "none"}:${scrollResetKey ?? "none"}`;
   const scrollRestorationId = targetMessageId
-    ? `message-timeline:${scrollRouteKey}:target:${targetMessageId}`
-    : `message-timeline:${scrollRouteKey}`;
-  // Keep the scroll node's DOM lifetime scoped to a channel. TanStack Router's
-  // scroll-restoration listener runs outside React and may write a saved
-  // scrollTop into the current scroll element during navigation; reusing the
-  // same node across channel routes can leave the newly-loaded message list
-  // painted at a stale offset until the user's next scroll event forces layout.
-  const scrollContainerDomKey = scrollRouteKey;
+    ? `message-timeline:${scrollIdentityKey}:target:${targetMessageId}`
+    : `message-timeline:${scrollIdentityKey}`;
+  // Keep the scroll node's DOM lifetime scoped to the rendered conversation.
+  // Channel layout changes (for example opening the thread panel) should keep
+  // this stable, while switching task conversations should start from a fresh
+  // scroll state.
+  const scrollContainerDomKey = scrollIdentityKey;
 
   const timelineBodySurface = selectTimelineBodySurface({
     deferredCount: deferredMessages.length,
@@ -265,7 +264,7 @@ const MessageTimelineBase = React.forwardRef<
     isLoading: showTimelineSkeleton,
     messages: deferredMessages,
     onTargetReached,
-    resetKey: scrollRouteKey,
+    resetKey: scrollIdentityKey,
     scrollContainerRef,
     targetMessageId,
   });

desktop/src/features/messages/ui/useAnchoredScroll.ts

@@ -38,10 +38,10 @@ type UseAnchoredScrollOptions = {
   /** Inner content element — must wrap every renderable row, including the
    *  sentinel and bottom anchor. Used to schedule layout work on resize. */
   contentRef: React.RefObject<HTMLDivElement | null>;
-  /** Resets when changed; lets us drop anchor + scroll state across channels. */
+  /** Scopes channel-level side effects and observer subscriptions. */
   channelId?: string | null;
   /** Resets when changed; includes channel plus route-specific layout state. */
-  resetKey?: string | null;
+  resetKey?: string | number | null;
   /** Suppresses initial scroll-to-bottom while a skeleton is showing. */
   isLoading: boolean;
   /** Source of truth for the rendered list. Used to detect new-at-bottom

desktop/tests/e2e/stream.spec.ts

@@ -42,10 +42,14 @@ async function ensureTimelineScrollable(
 ) {
   const input = senderPage.getByTestId("message-input");
   const sendButton = senderPage.getByTestId("send-message");
+  const minimumSeedMessages = 8;
 
   for (let index = 0; index < 24; index += 1) {
     const metrics = await getTimelineMetrics(receiverPage);
-    if (metrics.scrollHeight > metrics.clientHeight + 160) {
+    if (
+      index >= minimumSeedMessages &&
+      metrics.scrollHeight > metrics.clientHeight + 160
+    ) {
       return;
     }