fix: preserve plain-language current understanding

components/scenario-form.jsx

@@ -195,6 +195,7 @@ export default function ScenarioForm() {
   const [updateError, setUpdateError] = useState(null);
   const [updateResult, setUpdateResult] = useState(null);
   const [lastSubmittedAnswer, setLastSubmittedAnswer] = useState("");
+  const [currentUnderstanding, setCurrentUnderstanding] = useState(null);
   const textareaRef = useRef(null);
 
   /* Inject mock globals so the interceptor can read them at runtime */
@@ -219,8 +220,7 @@ export default function ScenarioForm() {
     setUpdateResult(null);
     setLastSubmittedAnswer("");
     setUpdateError(null);
-    setResult(null);
-    setUpdateResult(null);
+    setCurrentUnderstanding(null);
 
     try {
       const res = await submitScenarioForStartCase(MOCK_ENABLED ? mockFetch : fetch, scenario);
@@ -229,9 +229,11 @@ export default function ScenarioForm() {
 
       if (res.ok && data.success) {
         setStatus("success");
+        setCurrentUnderstanding(data.summary ?? null);
         setResult(normaliseStartResult(data));
       } else {
         setStatus("error");
+        setCurrentUnderstanding(data.summary ?? null);
         setResult(normaliseStartResult(data));
       }
     } catch (err) {
@@ -271,6 +273,9 @@ export default function ScenarioForm() {
 
       if (submission.ok && outcome.success) {
         setUpdateStatus("success");
+        setCurrentUnderstanding(
+          outcome.summary ? outcome.summary : currentUnderstanding,
+        );
         setUpdateResult({
           ...outcome,
           previousSituationGraph: result?.situationGraph ?? null,
@@ -340,6 +345,7 @@ export default function ScenarioForm() {
           scenario={scenario}
           status={status}
           updateStatus={updateStatus}
+          currentUnderstanding={currentUnderstanding}
           result={{
             ...(result || {}),
             situationGraph: updateResult?.updatedSituationGraph ?? result?.situationGraph,
@@ -367,6 +373,7 @@ export default function ScenarioForm() {
               setUpdateStatus("idle");
               setUpdateResult(null);
               setLastSubmittedAnswer("");
+              setCurrentUnderstanding(null);
               setUpdateError(null);
             }}
             className="rounded-lg border border-gray-300 px-4 py-2 text-sm font-medium text-gray-600 transition hover:bg-gray-50"