changed poll and some UI bugs.

frontend/src/App.jsx

@@ -36,7 +36,6 @@ export default function App() {
   const [loading, setLoading] = useState(true);
 
   async function refresh() {
-    setError('');
     try {
       const [healthResult, vmsResult, jobsResult, schedulesResult, nodesResult] = await Promise.allSettled([
         api.get('/health'),
@@ -47,20 +46,20 @@ export default function App() {
       ]);
 
       if (healthResult.status === 'fulfilled') {
-        setHealth(healthResult.value.data);
+        setStableState(setHealth, healthResult.value.data);
       } else {
-        setHealth(healthResult.reason.response?.data || { ok: false, checks: {} });
+        setStableState(setHealth, healthResult.reason.response?.data || { ok: false, checks: {} });
       }
 
-      if (vmsResult.status === 'fulfilled') setVms(vmsResult.value.data);
-      if (jobsResult.status === 'fulfilled') setJobs(jobsResult.value.data);
-      if (schedulesResult.status === 'fulfilled') setSchedules(schedulesResult.value.data);
-      if (nodesResult.status === 'fulfilled') setNodes(nodesResult.value.data);
+      if (vmsResult.status === 'fulfilled') setStableState(setVms, vmsResult.value.data);
+      if (jobsResult.status === 'fulfilled') setStableState(setJobs, jobsResult.value.data);
+      if (schedulesResult.status === 'fulfilled') setStableState(setSchedules, schedulesResult.value.data);
+      if (nodesResult.status === 'fulfilled') setStableState(setNodes, nodesResult.value.data);
 
       const firstFailure = [healthResult, vmsResult, jobsResult, schedulesResult, nodesResult].find((result) => result.status === 'rejected');
-      if (firstFailure) setError(errorMessage(firstFailure.reason));
+      setStableState(setError, firstFailure ? errorMessage(firstFailure.reason) : '');
     } catch (requestError) {
-      setError(errorMessage(requestError));
+      setStableState(setError, errorMessage(requestError));
     } finally {
       setLoading(false);
     }
@@ -227,6 +226,16 @@ export default function App() {
   }
 }
 
+function setStableState(setter, nextValue) {
+  setter((currentValue) => (
+    stableStringify(currentValue) === stableStringify(nextValue) ? currentValue : nextValue
+  ));
+}
+
+function stableStringify(value) {
+  return JSON.stringify(value);
+}
+
 function NavButton({ active, icon: Icon, label, onClick }) {
   return (
     <button