fix: individual yml download limit

src/renderer/pages/backup/BackupCreateFlow.tsx

@@ -21,6 +21,9 @@
 import environment from "shared/environment";
 import checks from "renderer/compatibility/checks";
 import { useTranslation } from "react-i18next";
+import legacyDownload from "js-file-download";
+import pLimit from "p-limit";
+import { delay } from "shared/tools";
 
 const notAvailable = !environment.isElectron && !checks.hasFilesystemApi;
 
@@ -179,7 +182,7 @@
     setProgress(0);
 
     const isoString = new Date().toISOString();
     const timestamp = isoString.replace(/[:.]/g, "-").split("T")[0]!;
 
     // Simulate progress
     const interval = setInterval(() => {
@@ -201,7 +204,7 @@
           includeLabels,
         },
       })
-        .then((result) => {
+        .then(async (result) => {
           clearInterval(interval);
           setProgress(100);
 
@@ -211,20 +214,23 @@
               base64Data: string;
             }[];
 
-            // Download each file
-            files.forEach((file: { fileName: string; base64Data: string }) => {
-              const blob = new Blob([Buffer.from(file.base64Data, "base64")], {
-                type: "application/octet-stream",
-              });
-              const url = URL.createObjectURL(blob);
-              const link = document.createElement("a");
-              link.href = url;
-              link.download = file.fileName;
-              document.body.appendChild(link);
-              link.click();
-              document.body.removeChild(link);
-              URL.revokeObjectURL(url);
-            });
+            // Limit concurrent downloads to avoid Chromium's rapid
+            // simultaneous download blocking (~10 at a time). Each slot
+            // holds for 200ms after triggering so Chromium registers it
+            // before the next batch starts.
+            const limit = pLimit(10);
+            await Promise.all(
+              files.map((file) =>
+                limit(async () => {
+                  legacyDownload(
+                    Buffer.from(file.base64Data, "base64"),
+                    file.fileName,
+                    "application/octet-stream"
+                  );
+                  await delay(200);
+                })
+              )
+            );
 
             void message.success(
               t(`{{count}} files downloaded`, { count: files.length })

src/renderer/pages/backup/__tests__/BackupCreateFlow.spec.tsx

@@ -1,9 +1,13 @@
 import React from "react";
 import { render } from "test-utils/testing-library";
-import { screen, waitFor } from "@testing-library/react";
+import { screen, waitFor, fireEvent } from "@testing-library/react";
 import { MockedProvider } from "@apollo/client/testing";
 import BackupCreateFlow from "renderer/pages/backup/BackupCreateFlow";
-import { describe, it, expect, vi, beforeAll, afterAll } from "vitest";
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import gql from "graphql-tag";
+import legacyDownload from "js-file-download";
+
+vi.mock("js-file-download");
 
 // Mock environment
 vi.mock("shared/environment", () => ({
@@ -20,29 +24,6 @@ vi.mock("renderer/compatibility/checks", () => ({
 }));
 
 describe("<BackupCreateFlow />", () => {
-  beforeAll(() => {
-    // Mock document.createElement for download links
-    const originalCreateElement = document.createElement.bind(document);
-    vi.spyOn(document, "createElement").mockImplementation(((
-      tagName: string
-    ) => {
-      const element = originalCreateElement(tagName);
-      if (tagName === "a") {
-        // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-explicit-any
-        (element as any).click = vi.fn();
-      }
-      return element;
-    }) as typeof document.createElement);
-
-    // Mock URL.createObjectURL and revokeObjectURL
-    global.URL.createObjectURL = vi.fn(() => "mock-url");
-    global.URL.revokeObjectURL = vi.fn();
-  });
-
-  afterAll(() => {
-    vi.restoreAllMocks();
-  });
-
   it("should render the component", () => {
     render(
       <MockedProvider mocks={[]}>
@@ -199,3 +180,173 @@ describe("<BackupCreateFlow />", () => {
     });
   });
 });
+
+describe("<BackupCreateFlow /> sequential individual download", () => {
+  let downloadedFiles: string[];
+  const mockLegacyDownload = vi.mocked(legacyDownload);
+
+  beforeEach(() => {
+    downloadedFiles = [];
+    mockLegacyDownload.mockImplementation((data: unknown, filename: string) => {
+      downloadedFiles.push(filename);
+    });
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it("should download all selected individual model files, not just the first 10", async () => {
+    const directoryId = "test-dir-id";
+    const modelCount = 11;
+    const modelNames = Array.from(
+      { length: modelCount },
+      (_, i) => `model${i + 1}`
+    );
+    const base64 = Buffer.from("content").toString("base64");
+
+    const mocks = [
+      {
+        request: {
+          query: gql`
+            mutation PickSdcardDirectory {
+              pickSdcardDirectory {
+                id
+              }
+            }
+          `,
+        },
+        result: {
+          data: {
+            pickSdcardDirectory: { id: directoryId },
+          },
+        },
+      },
+      {
+        request: {
+          query: gql`
+            query SdcardDirectoryInfo($directoryId: ID!) {
+              sdcardModelsDirectory(id: $directoryId) {
+                id
+                name
+                isValid
+                hasLabels
+                pack {
+                  target
+                  version
+                }
+              }
+            }
+          `,
+          variables: { directoryId },
+        },
+        result: {
+          data: {
+            sdcardModelsDirectory: {
+              id: directoryId,
+              name: "MODELS",
+              isValid: true,
+              hasLabels: false,
+              pack: null,
+            },
+          },
+        },
+      },
+      {
+        request: {
+          query: gql`
+            query SdcardModelsWithNames($directoryId: ID!) {
+              sdcardModelsWithNames(directoryId: $directoryId) {
+                fileName
+                displayName
+              }
+            }
+          `,
+          variables: { directoryId },
+        },
+        result: {
+          data: {
+            sdcardModelsWithNames: modelNames.map((name) => ({
+              fileName: name,
+              displayName: `Model ${name}`,
+            })),
+          },
+        },
+      },
+      {
+        request: {
+          query: gql`
+            mutation DownloadIndividualModels(
+              $directoryId: ID!
+              $selectedModels: [String!]!
+              $includeLabels: Boolean
+            ) {
+              downloadIndividualModels(
+                directoryId: $directoryId
+                selectedModels: $selectedModels
+                includeLabels: $includeLabels
+              ) {
+                fileName
+                base64Data
+              }
+            }
+          `,
+          variables: {
+            directoryId,
+            selectedModels: modelNames,
+            includeLabels: false,
+          },
+        },
+        result: {
+          data: {
+            downloadIndividualModels: modelNames.map((name) => ({
+              fileName: `${name}.yml`,
+              base64Data: base64,
+            })),
+          },
+        },
+      },
+    ];
+
+    render(
+      <MockedProvider mocks={mocks} addTypename={false}>
+        <BackupCreateFlow />
+      </MockedProvider>
+    );
+
+    // Trigger SD card selection
+    fireEvent.click(screen.getByText("Select SD Card"));
+
+    // Wait for Apollo mutation response and models to load
+    await waitFor(
+      () => {
+        expect(screen.getByText("Select all")).toBeInTheDocument();
+      },
+      { timeout: 3000 }
+    );
+
+    // Select all models
+    fireEvent.click(screen.getByText("Select all"));
+
+    // Switch to individual .yml format
+    fireEvent.click(screen.getByText("Individual .yml files"));
+
+    // Trigger backup download
+    fireEvent.click(screen.getByRole("button", { name: /create backup/i }));
+
+    // All 11 files should be downloaded (proves the 10-file Chromium limit is
+    // bypassed by downloading in batches of 10 with a 200ms delay per slot).
+    // With pLimit(10), 11 files need 2 batches (~400ms total).
+    await waitFor(
+      () => {
+        expect(downloadedFiles).toHaveLength(modelCount);
+      },
+      { timeout: 4000 }
+    );
+
+    // Verify each model file was included
+    modelNames.forEach((name) => {
+      expect(downloadedFiles).toContain(`${name}.yml`);
+    });
+  }, 10000); // extend test timeout to accommodate batched downloads with 200ms delay per slot
+});

src/shared/backend/__tests__/backup.spec.ts

@@ -1395,6 +1395,92 @@ describe("Backup", () => {
         expect(content).toContain("My Quad");
       });
 
+      it("should download all models when many are selected (e.g. 43)", async () => {
+        const modelsPath = await setupSdcardDirectory(tempDir.path);
+
+        // Create 43 model files to simulate a real-world scenario
+        const modelNames: string[] = [];
+        for (let i = 1; i <= 43; i += 1) {
+          const modelName = `model${i}`;
+          modelNames.push(modelName);
+          await fs.writeFile(
+            path.join(modelsPath, `${modelName}.yml`),
+            createModelYaml(`Model ${i}`)
+          );
+        }
+
+        // Pick directory
+        const handle = await getOriginPrivateDirectory(
+          nodeAdapter,
+          tempDir.path
+        );
+        // @ts-expect-error readonly but testing
+        handle.name = tempDir.path;
+        requestWritableDirectory.mockResolvedValueOnce(handle);
+
+        const pickResult = await backend.mutate({
+          mutation: gql`
+            mutation {
+              pickSdcardDirectory {
+                id
+              }
+            }
+          `,
+        });
+
+        const directoryId = (pickResult.data?.pickSdcardDirectory as any)?.id;
+
+        // Download all 43 models
+        const { data, errors } = await backend.mutate({
+          mutation: gql`
+            mutation DownloadModels(
+              $directoryId: ID!
+              $selectedModels: [String!]!
+            ) {
+              downloadIndividualModels(
+                directoryId: $directoryId
+                selectedModels: $selectedModels
+              ) {
+                fileName
+                base64Data
+              }
+            }
+          `,
+          variables: {
+            directoryId,
+            selectedModels: modelNames,
+          },
+        });
+
+        expect(errors).toBeFalsy();
+        expect(data?.downloadIndividualModels).toHaveLength(43);
+
+        // Verify all 43 files are present
+        const downloadedFiles = (
+          data?.downloadIndividualModels as {
+            fileName: string;
+            base64Data: string;
+          }[]
+        ).map((m) => m.fileName);
+
+        for (let i = 1; i <= 43; i += 1) {
+          expect(downloadedFiles).toContain(`model${i}.yml`);
+        }
+
+        // Verify content of a few samples
+        const model25 = (
+          data?.downloadIndividualModels as {
+            fileName: string;
+            base64Data: string;
+          }[]
+        ).find((m) => m.fileName === "model25.yml");
+        const content = Buffer.from(
+          model25?.base64Data ?? "",
+          "base64"
+        ).toString("utf-8");
+        expect(content).toContain("Model 25");
+      });
+
       it("should include labels file when requested", async () => {
         const modelsPath = await setupSdcardDirectory(tempDir.path);