fix(platform): fall back to the model's own name when displayName is left empty

ModelManagement shows the resolved model name as the display-name placeholder; WorkbenchModel save maps empty displayName to the model's cascader label so the workspace model picker never renders a blank option.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/frontend/platform/src/pages/BuildPage/bench/ModelManagement.tsx

@@ -43,6 +43,17 @@ export const ModelManagement = forwardRef<HTMLDivElement[], ModelManagementProps
         const { t } = useTranslation();
         const navigate = useNavigate();
 
+        // Resolve the selected model's name from the cascader options so the
+        // display-name input can fall back to it as placeholder when left empty.
+        const getModelLabel = (id: string) => {
+            if (!id) return '';
+            for (const group of assistantLlmOptions) {
+                const hit = group.children?.find((el) => el.value == id);
+                if (hit) return hit.label;
+            }
+            return '';
+        };
+
         const selectFooter = (
             <div
                 className="px-3 py-2 text-sm text-primary cursor-pointer hover:bg-[#EBF0FF] dark:hover:bg-gray-700"
@@ -125,7 +136,7 @@ export const ModelManagement = forwardRef<HTMLDivElement[], ModelManagementProps
                             <Input
                                 value={model.displayName}
                                 onChange={(e) => onNameChange(index, e.target.value)}
-                                placeholder={t('bench.displayName')}
+                                placeholder={getModelLabel(model.id) || t('bench.displayName')}
                             />
                             {errors[model.key] && <p className="text-red-500 text-xs mt-1">{errors[model.key]?.[1]}</p>}
                         </div>

src/frontend/platform/src/pages/ModelPage/manage/tabs/WorkbenchModel.tsx

@@ -76,6 +76,17 @@ export default function WorkbenchModel({ onBack }) {
 
     const { data: linsightConfig, isLoading: loading, refetch: refetchConfig, error } = useLinsightConfig();
 
+    // Look up the model's own name from the cascader options by id, used as
+    // the default displayName when the admin leaves it empty.
+    const findModelLabel = (id) => {
+        if (!id) return '';
+        for (const group of llmOptions) {
+            const hit = group.children?.find((el) => el.value == id);
+            if (hit) return hit.label;
+        }
+        return '';
+    };
+
     const handleSave = async () => {
         const { linsightDefaultModelId, sourceModelId, asrModelId, ttsModelId, chatTitleLlmId, models } = form;
         const errors = [];
@@ -86,7 +97,9 @@ export default function WorkbenchModel({ onBack }) {
         setSaveLoad(true);
         try {
             const data = {
-                models,
+                // Empty displayName falls back to the model's own name so the
+                // workspace model picker never renders a blank option.
+                models: models.map((m) => m.displayName ? m : { ...m, displayName: findModelLabel(m.id) }),
                 embedding_model: { id: String(sourceModelId) },
                 // Linsight default executor model: one of the workbench chat models' id.
                 linsight_default_model_id: linsightDefaultModelId ? String(linsightDefaultModelId) : null,