Disable dataset Save until the form is valid (§05)

src/app/components/DatasetsModal.tsx

@@ -19,7 +19,12 @@ import { detectFormat, detectFormatFromUrl, type DataFormat } from '@core/format
 import { closeModal, openModal, resnapshot } from '../modals/ModalCoordinator';
 import { confirm } from '../stores/ConfirmStore';
 import { notify } from '../stores/NotificationStore';
-import { selectSelectedDataset, useDatasetStore, byModifiedDesc } from '../stores/DatasetStore';
+import {
+  selectCanSave,
+  selectSelectedDataset,
+  useDatasetStore,
+  byModifiedDesc,
+} from '../stores/DatasetStore';
 import { useSnippetStore } from '../stores/SnippetStore';
 import { SegmentedControl, type SegmentedOption } from './SegmentedControl';
 import { Icon } from './Icon';
@@ -338,6 +343,8 @@ function DatasetFormView({ editing }: { editing: boolean }) {
   const updateForm = useDatasetStore((s) => s.updateForm);
   const cancelForm = useDatasetStore((s) => s.cancelForm);
   const save = useDatasetStore((s) => s.save);
+  // Save stays disabled until a name and valid data/URL are present (spec §05).
+  const canSave = useDatasetStore(selectCanSave);
 
   // Live format/source hint from the current input (spec §05 → Auto-detection).
   const detected =
@@ -433,7 +440,12 @@ function DatasetFormView({ editing }: { editing: boolean }) {
         <button type="button" className={styles.action} onClick={handleCancel}>
           Cancel
         </button>
-        <button type="button" className={`${styles.action} ${styles.primary}`} onClick={handleSave}>
+        <button
+          type="button"
+          className={`${styles.action} ${styles.primary}`}
+          disabled={!canSave}
+          onClick={handleSave}
+        >
           {editing ? 'Save changes' : 'Create dataset'}
         </button>
       </div>