fix: prevent cmd-k scroll reset on catalog poll refresh

The searchData useMemo recomputed on every catalog poll cycle because
catalogData got a new array reference even when content was unchanged.
This caused the CommandPalette list to re-render and reset scroll.

Use a ref with deep equality check to keep a stable catalog reference,
only updating when the actual data changes.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/components/LayoutShell.tsx

@@ -5,7 +5,7 @@ import { useRouteCatalog } from '../api/queries/catalog';
 import { useAgents } from '../api/queries/agents';
 import { useSearchExecutions } from '../api/queries/executions';
 import { useAuthStore } from '../auth/auth-store';
-import { useState, useMemo, useCallback, useEffect } from 'react';
+import { useState, useMemo, useCallback, useEffect, useRef } from 'react';
 import { ContentTabs } from './ContentTabs';
 import { useScope } from '../hooks/useScope';
 
@@ -145,6 +145,13 @@ function LayoutContent() {
     [catalog, agents],
   );
 
+  // Stable reference for catalog data — only changes when catalog/agents actually change,
+  // not on every poll cycle (prevents cmd-k scroll reset)
+  const catalogRef = useRef(catalogData);
+  if (catalogData !== catalogRef.current && JSON.stringify(catalogData) !== JSON.stringify(catalogRef.current)) {
+    catalogRef.current = catalogData;
+  }
+
   const searchData: SearchResult[] = useMemo(() => {
     const exchangeItems: SearchResult[] = (exchangeResults?.data || []).map((e: any) => ({
       id: e.executionId,
@@ -178,8 +185,8 @@ function LayoutContent() {
       }
     }
 
-    return [...catalogData, ...exchangeItems, ...attributeItems];
-  }, [catalogData, exchangeResults, debouncedQuery]);
+    return [...catalogRef.current, ...exchangeItems, ...attributeItems];
+  }, [catalogRef.current, exchangeResults, debouncedQuery]);
 
   const isAdminPage = location.pathname.startsWith('/admin');
   const breadcrumb = useMemo(() => {