diff --git a/frontend/src/app/dashboard/service/user/download/download.service.spec.ts b/frontend/src/app/dashboard/service/user/download/download.service.spec.ts
index 30bd0533814..7bc180e7377 100644
--- a/frontend/src/app/dashboard/service/user/download/download.service.spec.ts
+++ b/frontend/src/app/dashboard/service/user/download/download.service.spec.ts
@@ -29,6 +29,7 @@ import { commonTestProviders } from "../../../../common/testing/test-utils";
 import type { Mocked } from "vitest";
 import { WORKFLOW_EXECUTIONS_API_BASE_URL } from "../workflow-executions/workflow-executions.service";
 import { DashboardWorkflowComputingUnit } from "../../../../common/type/workflow-computing-unit";
+import JSZip from "jszip";
 
 function computingUnit(type: string, cuid: number): DashboardWorkflowComputingUnit {
   return { computingUnit: { cuid, type } } as unknown as DashboardWorkflowComputingUnit;
@@ -224,6 +225,47 @@ describe("DownloadService", () => {
     expect(notificationServiceSpy.error).toHaveBeenCalledWith("Error downloading workflows as ZIP");
   });
 
+  // ─── createWorkflowsZip / nameWorkflow (real zip assembly) ────────────────
+  // These drive downloadWorkflowsAsZip through the real (un-mocked) private
+  // createWorkflowsZip → downloadWorkflow → nameWorkflow chain, so the produced
+  // blob is a genuine zip we can load back and inspect.
+
+  it("assembles a real zip with one JSON entry per workflow", async () => {
+    workflowPersistServiceSpy.retrieveWorkflow.mockReturnValue(of({ content: { op: "x" } } as any));
+
+    const result = await firstValueFrom(
+      downloadService.downloadWorkflowsAsZip([
+        { id: 1, name: "Alpha" },
+        { id: 2, name: "Beta" },
+      ])
+    );
+
+    expect(result).toBeInstanceOf(Blob);
+    expect(workflowPersistServiceSpy.retrieveWorkflow).toHaveBeenCalledWith(1);
+    expect(workflowPersistServiceSpy.retrieveWorkflow).toHaveBeenCalledWith(2);
+    expect(fileSaverServiceSpy.saveAs).toHaveBeenCalledWith(result, expect.stringMatching(/^workflowExports-.*\.zip$/));
+    expect(notificationServiceSpy.success).toHaveBeenCalledWith("Workflows have been downloaded as ZIP");
+
+    const loaded = await JSZip.loadAsync(result);
+    expect(Object.keys(loaded.files).sort()).toEqual(["Alpha.json", "Beta.json"]);
+  });
+
+  it("de-duplicates colliding workflow filenames inside the zip", async () => {
+    workflowPersistServiceSpy.retrieveWorkflow.mockReturnValue(of({ content: { op: "x" } } as any));
+
+    const result = await firstValueFrom(
+      downloadService.downloadWorkflowsAsZip([
+        { id: 1, name: "Dup" },
+        { id: 2, name: "Dup" },
+        { id: 3, name: "Dup" },
+      ])
+    );
+
+    // nameWorkflow appends -1, -2, ... on each collision so no entry is lost.
+    const loaded = await JSZip.loadAsync(result);
+    expect(Object.keys(loaded.files).sort()).toEqual(["Dup-1.json", "Dup-2.json", "Dup.json"]);
+  });
+
   // ─── downloadOperatorsResult ──────────────────────────────────────────────
 
   it("downloads a single operator file directly when there's exactly one file", async () => {
@@ -241,14 +283,10 @@ describe("DownloadService", () => {
     expect(notificationServiceSpy.success).toHaveBeenCalledWith("Operator result has been downloaded");
   });
 
-  // The multi-file zip path goes through `new JSZip()` against the
-  // `import * as JSZip from "jszip"` namespace, which the build flags as
-  // `Constructing "JSZip" will crash at run-time because it's an import
-  // namespace object`. Vitest reproduces the failure (`__vite_ssr_import_*
-  // is not a constructor`). Tracked as a separate cleanup in the codebase;
-  // the test is here as a placeholder so we re-enable it once the import
-  // is normalised to a default import.
-  it.skip("zips multiple operator files into a workflow-named archive", async () => {
+  // The multi-file zip path goes through `new JSZip()`; now that the source
+  // imports JSZip as a default import (rather than an import namespace object),
+  // it constructs correctly under Vitest so this exercises the real archive.
+  it("zips multiple operator files into a workflow-named archive", async () => {
     const a = new Blob(["a"], { type: "text/plain" });
     const b = new Blob(["b"], { type: "text/plain" });
     const result = await firstValueFrom(
@@ -264,8 +302,32 @@ describe("DownloadService", () => {
     );
 
     expect(result).toBeInstanceOf(Blob);
+    expect(notificationServiceSpy.info).toHaveBeenCalledWith("Starting to download operator results as ZIP");
     expect(fileSaverServiceSpy.saveAs).toHaveBeenCalledWith(expect.any(Blob), "results_7_TwoFile.zip");
     expect(notificationServiceSpy.success).toHaveBeenCalledWith("Operator results have been downloaded as ZIP");
+
+    // The produced blob is a real zip carrying both operator files.
+    const loaded = await JSZip.loadAsync(result);
+    expect(Object.keys(loaded.files).sort()).toEqual(["a.csv", "b.csv"]);
+  });
+
+  it("flattens operator result batches before deciding single vs zip", async () => {
+    // Two source observables, each emitting one file: flat() merges them into
+    // two files, which routes through the multi-file zip branch.
+    const result = await firstValueFrom(
+      downloadService.downloadOperatorsResult(
+        [
+          of([{ filename: "first.csv", blob: new Blob(["1"], { type: "text/plain" }) }]),
+          of([{ filename: "second.csv", blob: new Blob(["2"], { type: "text/plain" }) }]),
+        ],
+        { wid: 3, name: "Flat" } as any
+      )
+    );
+
+    expect(result).toBeInstanceOf(Blob);
+    expect(fileSaverServiceSpy.saveAs).toHaveBeenCalledWith(expect.any(Blob), "results_3_Flat.zip");
+    const loaded = await JSZip.loadAsync(result);
+    expect(Object.keys(loaded.files).sort()).toEqual(["first.csv", "second.csv"]);
   });
 
   it("errors out cleanly when no operator result files are provided", async () => {
@@ -409,6 +471,30 @@ describe("DownloadService", () => {
       expect(document.querySelector('iframe[name="download-iframe"]')).toBeNull();
     });
 
+    it("falls back to an empty token when none is stored", () => {
+      // Override the beforeEach stub so getItem returns null, exercising the
+      // `?? ""` fallback on the auth token.
+      vi.stubGlobal("localStorage", {
+        getItem: vi.fn().mockReturnValue(null),
+        setItem: vi.fn(),
+        removeItem: vi.fn(),
+      });
+
+      downloadService.exportWorkflowResultToLocal(
+        "csv",
+        1,
+        "WF",
+        EXPORT_OPERATORS,
+        0,
+        0,
+        "out.csv",
+        computingUnit("local", 5)
+      );
+
+      const form = document.querySelector('form[target="download-iframe"]') as HTMLFormElement;
+      expect((form.querySelector('input[name="token"]') as HTMLInputElement).value).toBe("");
+    });
+
     it("targets the cuid-scoped endpoint for a kubernetes computing unit", () => {
       downloadService.exportWorkflowResultToLocal(
         "csv",
diff --git a/frontend/src/app/dashboard/service/user/download/download.service.ts b/frontend/src/app/dashboard/service/user/download/download.service.ts
index 811ebe37f47..2b7e5544e2a 100644
--- a/frontend/src/app/dashboard/service/user/download/download.service.ts
+++ b/frontend/src/app/dashboard/service/user/download/download.service.ts
@@ -24,7 +24,7 @@ import { FileSaverService } from "../file/file-saver.service";
 import { NotificationService } from "../../../../common/service/notification/notification.service";
 import { DatasetService } from "../dataset/dataset.service";
 import { WorkflowPersistService } from "src/app/common/service/workflow-persist/workflow-persist.service";
-import * as JSZip from "jszip";
+import JSZip from "jszip";
 import { Workflow } from "../../../../common/type/workflow";
 import { HttpClient, HttpResponse } from "@angular/common/http";
 import { WORKFLOW_EXECUTIONS_API_BASE_URL } from "../workflow-executions/workflow-executions.service";