Add distributed settings and workspace import/export (M5)

src/app/stores/DatasetStore.ts

@@ -69,6 +69,14 @@ export interface DatasetState {
 
   /** Low-level: add a fully-formed dataset and select it. */
   add: (dataset: Dataset) => void;
+  /**
+   * Append imported datasets (spec §08 → datasets imported before snippets). Each
+   * is given a fresh monotonic numeric id so a batch never collides on the
+   * `Date.now()` default (the `add` TODO) nor with existing ids — safe because
+   * datasets are referenced by **name**, not id (docs/architecture/07 §1). Names
+   * are assumed already de-duped by the import service. Selection is unchanged.
+   */
+  addDatasets: (incoming: Dataset[]) => void;
   /** Low-level: merge a patch into a dataset, advancing `modified`. */
   update: (id: number, patch: Partial<Dataset>, now?: Date) => void;
   /** Low-level: remove a dataset; clears the selection if it was selected. */
@@ -237,6 +245,15 @@ export const useDatasetStore = create<DatasetState>((set, get) => ({
   // before wiring import.
   add: (dataset) => set((s) => ({ datasets: [dataset, ...s.datasets], selectedId: dataset.id })),
 
+  addDatasets: (incoming) => {
+    if (incoming.length === 0) return;
+    set((s) => {
+      let nextId = s.datasets.reduce((max, d) => Math.max(max, d.id), 0) + 1;
+      const withIds = incoming.map((d) => ({ ...d, id: nextId++ }));
+      return { datasets: [...withIds, ...s.datasets] };
+    });
+  },
+
   update: (id, patch, now) => {
     const modified = patch.modified ?? (now ?? new Date()).toISOString();
     set((s) => ({