fix: preserve blank-name backups and open linked bill editors

src/export/json.test.ts

@@ -6,6 +6,7 @@ import {
   ImportValidationError,
   exportFilename,
 } from "./json.ts";
+import { addRecurringCost, updatePost, updateRecurringCost } from "../store/actions.ts";
 import { createSeedDataset } from "../domain/seed.ts";
 import { monthView, yearView } from "../domain/views.ts";
 import type { Dataset } from "../domain/types.ts";
@@ -164,21 +165,33 @@ describe("import rejects invalid folder graph", () => {
     expect(() => parse(data)).toThrow(ImportValidationError);
   });
 
-  test("rejects a blank post name", () => {
+  test.each([
+    ["", "Rent"], ["  ", "Rent"], ["Games", ""], ["Games", "  "],
+  ])("blank item names (%j, %j) survive saved dataset round trips and v7 import", (postName, billName) => {
     const data = populated();
-    data.posts[0]!.name = "  ";
-    expect(() => parse(data)).toThrow(ImportValidationError);
-  });
-
-  test("rejects a blank recurring-cost name", () => {
-    const data = populated();
-    data.recurring.push({
-      id: "rent", name: "  ", order: 3, folderId: null, archived: false,
+    const bill = addRecurringCost(data, {
+      name: "Rent", folderId: null, archived: false,
       amount: { amount: 100, currency: "DKK" }, startDate: "2026-01",
       recurrence: { kind: "everyNMonths", n: 1 }, anchoring: "calendar",
       splitMode: "percent", splits: [{ postId: data.posts[0]!.id, value: 100, absorbsRemainder: true }],
     });
-    expect(() => parse(data)).toThrow(ImportValidationError);
+    updatePost(data, data.posts[0]!.id, { name: postName });
+    updateRecurringCost(data, bill.id, { name: billName });
+    expect(parseDatasetJson(exportDatasetJson(data))).toEqual(data);
+    const legacy = JSON.parse(exportDatasetJson(data));
+    legacy.settings.schemaVersion = 7;
+    delete legacy.folders;
+    for (const item of [...legacy.posts, ...legacy.recurring]) delete item.folderId;
+    const imported = parseDatasetJson(JSON.stringify(legacy));
+    expect(imported.posts[0]!.name).toBe(postName);
+    expect(imported.recurring[0]!.name).toBe(billName);
+    expect(imported.folders).toEqual([]);
+  });
+
+  test.each(["", "  "])("still rejects blank folder names %j", name => {
+    const data = populated();
+    data.folders = [{ ...folder("home", null, data.posts.length), name }];
+    expect(() => parse(data)).toThrow(/empty name/);
   });
 });