fix: unique ZIP folders for same-named batch PDFs

Readme.md

@@ -11,6 +11,7 @@ This project is a comprehensive full‑stack web app for doing simple, local fil
 **PDF Tools:**
 
 - Convert PDF pages to PNG (single page, range, or all pages)
+- Batch-convert multiple PDFs to PNG with unique ZIP folders for same-named files
 - Merge multiple PDF files into one document, including files with the same name
 - Split a PDF by extracting a page range into a new document
 - Convert PDF to DOCX

frontend/src/pages/PdfPngBatch.tsx

@@ -17,6 +17,7 @@ import {
 import { clsx } from "clsx";
 import { twMerge } from "tailwind-merge";
 import PrimaryButton from "../components/UI/PrimaryButton";
+import { uniqueZipFolderName } from "../utils/uniqueZipFolderName";
 
 pdfjsLib.GlobalWorkerOptions.workerSrc = pdfWorker;
 
@@ -120,6 +121,7 @@ export default function PdfPngBatch() {
 
     const zip = new JSZip();
     let done = 0;
+    const usedFolderNames = new Set<string>();
 
     try {
       for (let i = 0; i < files.length; i++) {
@@ -129,7 +131,8 @@ export default function PdfPngBatch() {
           setFileProgress(Math.round((page / total) * 100));
         });
         // If a batch contains multiple files, namespace PNGs into a folder per file.
-        const folder = files.length > 1 ? zip.folder(result.name) : zip;
+        const folderName = uniqueZipFolderName(result.name, usedFolderNames);
+        const folder = files.length > 1 ? zip.folder(folderName) : zip;
         for (const p of result.pages) {
           folder.file(p.name, p.blob);
         }

frontend/src/utils/uniqueZipFolderName.test.ts

@@ -0,0 +1,20 @@
+import { describe, expect, it } from "vitest";
+
+import { uniqueZipFolderName } from "./uniqueZipFolderName";
+
+describe("uniqueZipFolderName", () => {
+  it("keeps the first name and suffixes later collisions", () => {
+    const used = new Set<string>();
+
+    expect(uniqueZipFolderName("report", used)).toBe("report");
+    expect(uniqueZipFolderName("report", used)).toBe("report-2");
+    expect(uniqueZipFolderName("report", used)).toBe("report-3");
+    expect(uniqueZipFolderName("invoice", used)).toBe("invoice");
+  });
+
+  it("skips suffixes that are already claimed", () => {
+    const used = new Set<string>(["report", "report-2"]);
+
+    expect(uniqueZipFolderName("report", used)).toBe("report-3");
+  });
+});

frontend/src/utils/uniqueZipFolderName.ts

@@ -0,0 +1,22 @@
+/**
+ * Pick a ZIP folder name that does not collide with names already claimed
+ * in the current archive. First use keeps the base name; later collisions
+ * get a numeric suffix (`report`, `report-2`, ...).
+ */
+export function uniqueZipFolderName(baseName: string, usedNames: Set<string>) {
+  const normalized = baseName.trim() || "document";
+  if (!usedNames.has(normalized)) {
+    usedNames.add(normalized);
+    return normalized;
+  }
+
+  let suffix = 2;
+  let candidate = `${normalized}-${suffix}`;
+  while (usedNames.has(candidate)) {
+    suffix += 1;
+    candidate = `${normalized}-${suffix}`;
+  }
+
+  usedNames.add(candidate);
+  return candidate;
+}