Preserve QExcell hidden sheets in XLSX

src/io/excellOffice.test.ts

@@ -513,6 +513,16 @@ describe("excellOffice OOXML helpers", () => {
       })
     ).toEqual([{ id: "sheet-7", name: "Бюджет", relationshipId: "rId3" }]);
 
+    expect(
+      workbookSheetRefs({
+        workbook: {
+          sheets: {
+            sheet: { name: "Архив", sheetId: "8", "r:id": "rId4", state: "hidden" }
+          }
+        }
+      })
+    ).toEqual([{ id: "sheet-8", name: "Архив", visibility: "hidden", relationshipId: "rId4" }]);
+
     expect(
       workbookRelationshipTargets({
         Relationships: {
@@ -555,6 +565,28 @@ describe("excellOffice OOXML helpers", () => {
     expect(imported.activeSheet).toBe("sheet-2");
   });
 
+  it("сохраняет и импортирует скрытые листы XLSX через sheet state", async () => {
+    const blob = await exportXlsxBlob({
+      id: "book-1",
+      title: "Скрытые листы.xlsx",
+      updatedAt: "2026-06-01T00:00:00.000Z",
+      activeSheet: "sheet-1",
+      sheets: [
+        { id: "sheet-1", name: "Рабочий", cells: { A1: "Открыт" } },
+        { id: "sheet-2", name: "Архив", visibility: "hidden", cells: { A1: "Скрыт" } },
+        { id: "sheet-3", name: "Служебный", visibility: "veryHidden", cells: { A1: "Очень скрыт" } }
+      ]
+    });
+    const zip = await JSZip.loadAsync(await blob.arrayBuffer());
+    const workbookXml = await zip.file("xl/workbook.xml")?.async("string");
+    const imported = await importXlsxFile(new File([blob], "Скрытые листы.xlsx", { type: blob.type }));
+
+    expect(workbookXml).toContain('<sheet name="Архив" sheetId="2" r:id="rId2" state="hidden"/>');
+    expect(workbookXml).toContain('<sheet name="Служебный" sheetId="3" r:id="rId3" state="veryHidden"/>');
+    expect(imported.sheets[1]).toMatchObject({ id: "sheet-2", name: "Архив", visibility: "hidden" });
+    expect(imported.sheets[2]).toMatchObject({ id: "sheet-3", name: "Служебный", visibility: "veryHidden" });
+  });
+
   it("создает OOXML chart part для диаграммы XLSX", () => {
     const xml = buildChartXml(
       {