fix(web): preserve overflow toggle spacing

Author: maria-rcks

apps/web/src/components/chat/MessagesTimeline.logic.test.ts

@@ -1683,7 +1683,7 @@ describe("deriveMessagesTimelineRows", () => {
   });
 
   it("labels mixed-group overflow from the entries actually hidden", () => {
-    const rows = deriveMessagesTimelineRows({
+    const input = {
       timelineEntries: [
         {
           id: "tool-entry-1",
@@ -1724,12 +1724,23 @@ describe("deriveMessagesTimelineRows", () => {
       activeTurnStartedAt: null,
       turnDiffSummaryByAssistantMessageId: new Map(),
       revertTurnCountByUserMessageId: new Map(),
+    } satisfies Parameters<typeof deriveMessagesTimelineRows>[0];
+    const rows = deriveMessagesTimelineRows(input);
+    const expandedRows = deriveMessagesTimelineRows({
+      ...input,
+      expandedWorkGroupIds: new Set(["work-group:tool-entry-1"]),
     });
 
     expect(rows.find((row) => row.kind === "work-toggle")).toMatchObject({
       hiddenCount: 1,
       onlyToolEntries: true,
     });
+    expect(expandedRows.at(-1)).toMatchObject({
+      kind: "work-toggle",
+      expanded: true,
+      onlyToolEntries: true,
+      summary: null,
+    });
   });
 
   it("keeps error entries visible instead of summarizing them as tools", () => {

apps/web/src/components/chat/MessagesTimeline.tsx

@@ -915,7 +915,7 @@ const TimelineRowContent = memo(function TimelineRowContent({ row }: { row: Time
   const isExpandedToolGroupEntry = row.kind === "work" && row.isExpandedToolGroupEntry;
   const isLastExpandedToolGroupEntry = row.kind === "work" && row.isLastExpandedToolGroupEntry;
   const isExpandedToolGroupHeader =
-    (row.kind === "work-toggle" && row.onlyToolEntries && row.expanded) ||
+    (row.kind === "work-toggle" && row.summary !== null && row.onlyToolEntries && row.expanded) ||
     (row.kind === "work-live" && row.expanded);
 
   return (