diff --git a/gui-ts/src/ui/App.tsx b/gui-ts/src/ui/App.tsx
index 6629924..ae2f8e1 100644
--- a/gui-ts/src/ui/App.tsx
+++ b/gui-ts/src/ui/App.tsx
@@ -48,6 +48,7 @@ export function App() {
   const [surfaceCardQaError, setSurfaceCardQaError] = useState<string | null>(null);
   const [validatingSurfaceCard, setValidatingSurfaceCard] = useState(false);
   const hydrated = useRef(false);
+  const latestRunToken = useRef(0);
   const engineeringChecks = useMemo(() => runEngineeringChecks(store.state), [store.state]);
 
   useEffect(() => {
@@ -96,6 +97,8 @@ export function App() {
   }, [parsedSurfaceCard]);
 
   const handleRun = useCallback(async () => {
+    const runToken = latestRunToken.current + 1;
+    latestRunToken.current = runToken;
     if (engineeringChecks.hasBlockingError) {
       setError("Please fix blocking engineering checks before running the solver.");
       setStatusMessage("Blocked by engineering checks");
@@ -133,6 +136,9 @@ export function App() {
           fourierHarmonics: runSettings.outputOptions.fourierHarmonics
         }
       });
+      if (latestRunToken.current !== runToken) {
+        return;
+      }
       setResult(resp);
       const dt = (performance.now() - t0) / 1000;
       setElapsed(dt);
@@ -140,10 +146,15 @@ export function App() {
       setStatusMessage(`Done in ${dt.toFixed(1)}s`);
       setActiveTab("tab-results");
     } catch (e) {
+      if (latestRunToken.current !== runToken) {
+        return;
+      }
       setError(e instanceof Error ? e.message : String(e));
       setStatusMessage("Error");
     } finally {
-      setLoading(false);
+      if (latestRunToken.current === runToken) {
+        setLoading(false);
+      }
     }
   }, [engineeringChecks.hasBlockingError, parsedSurfaceCard, runSettings, store.state]);
 
diff --git a/gui-ts/src/ui/tabs/ResultsTab.tsx b/gui-ts/src/ui/tabs/ResultsTab.tsx
index c105564..6934d4f 100644
--- a/gui-ts/src/ui/tabs/ResultsTab.tsx
+++ b/gui-ts/src/ui/tabs/ResultsTab.tsx
@@ -122,6 +122,12 @@ export function ResultsTab({
     }
     return [fdmSeries.position, fdmSeries.polished, fdmSeries.downhole] as AlignedData;
   }, [fdm, fea]);
+  const hasCardLengthMismatch = useMemo(() => {
+    const fdmSeries = toSeries(fdm ?? undefined);
+    const feaSeries = toSeries(fea ?? undefined);
+    if (!fdmSeries || !feaSeries) return false;
+    return fdmSeries.position.length !== feaSeries.position.length;
+  }, [fdm, fea]);
 
   const dynacardOptions = useMemo<Options>(() => {
     const seriesCount = fea ? 5 : 3;
@@ -364,6 +370,11 @@ export function ResultsTab({
           </Fieldset>
 
           <Fieldset legend="Dynamometer Card">
+            {hasCardLengthMismatch && (
+              <div className="callout">
+                FDM and FEA card lengths differ; chart overlay is limited to FDM series for this run.
+              </div>
+            )}
             {dynacardData ? (
               <UPlotChart data={dynacardData} options={dynacardOptions} height={340} />
             ) : (