fix(web): prevent subagent sessions from leaking into chat sidebar

- Skip updateIndex for session IDs containing :subagent: so they don't
  appear as top-level "New Chat" entries in the sidebar
- Filter subagent IDs in the sidebar component as a safety net
- Clean up existing leaked entries from index.json

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/web/app/components/workspace/chat-sessions-sidebar.tsx

@@ -220,8 +220,13 @@ export function ChatSessionsSidebar({
 		return map;
 	}, [subagents]);
 
+	const filteredSessions = useMemo(
+		() => sessions.filter((s) => !s.id.includes(":subagent:")),
+		[sessions],
+	);
+
 	// Group sessions: today, yesterday, this week, this month, older
-	const grouped = groupSessions(sessions);
+	const grouped = groupSessions(filteredSessions);
 
 	const width = mobile ? "280px" : (widthProp ?? 260);
 	const headerHeight = 40; // px — match padding so list content clears the overlay

apps/web/lib/active-runs.ts

@@ -1557,12 +1557,17 @@ function upsertMessage(
 
 	if (!found) {
 		updated.push(JSON.stringify(message));
-		updateIndex(sessionId, { incrementCount: 1 });
-	} else {
-		updateIndex(sessionId, {});
 	}
 
 	writeFileSync(fp, updated.join("\n") + "\n");
+
+	if (!sessionId.includes(":subagent:")) {
+		if (!found) {
+			updateIndex(sessionId, { incrementCount: 1 });
+		} else {
+			updateIndex(sessionId, {});
+		}
+	}
 }
 
 function cleanupRun(sessionId: string) {