.prettierignore

@@ -0,0 +1,4 @@
+node_modules
+coverage
+dist
+*.zip

.prettierrc.json

@@ -0,0 +1,6 @@
+{
+  "singleQuote": true,
+  "semi": true,
+  "trailingComma": "es5",
+  "printWidth": 80
+}

CHANGELOG.md

@@ -4,6 +4,42 @@ All notable changes to `pdf-tools` are documented here.
 
 The project follows a pragmatic versioning scheme while the app is still below `1.0.0`: minor versions mark coherent user-facing milestones; patch versions mark fixes and small improvements.
 
+## 0.3.0 — Selection workspace and maintenance release
+
+### Added
+
+- Added “Open selection as workspace” to create a new unsaved active workspace from the selected pages in current visual order.
+- Added selection-workspace helper tests for visual-order selection and derived naming.
+- Added TypeScript type-check, ESLint, Prettier, and aggregate `check` scripts.
+- Added ESLint flat config with TypeScript, React Hooks, React Refresh, browser, and Node config support.
+- Added Prettier configuration and ignore file.
+- Added Vite client type declarations for worker URL imports.
+- Added Vitest-based test scripts for one-off and watch-mode test runs.
+- Added pure tests for workspace command cloning, snapshot command stability, and serializable command record round-tripping.
+- Added hook-level tests for workspace load/replace behavior, command execution, undo, redo, history, redo clearing, dirty-state updates, and content-change callbacks.
+
+### Changed
+
+- Bumped the app/package version to `0.3.0`.
+- Switched to `@vitejs/plugin-react`.
+- Marked the package as an ES module package to remove the Vite CJS Node API deprecation warning during local tooling runs.
+- Ran Prettier across the project after adding the formatting configuration.
+- Split the former monolithic `ReorderPanel` into focused page-workspace components: `PageGrid`, `PageCard`, `PageSelectionToolbar`, `DropIndicator`, and `CopyPagesDialog`.
+- Kept drag/drop move, Ctrl/⌘ copy-drag, selection, rotation, deletion, preview opening, and copy-by-position behavior wired through the existing `ReorderPanel` API.
+- Extracted generated PDF download URL creation and cleanup for split, extract, and export results into `src/hooks/usePdfGeneratedOutputs.ts`.
+- Updated `ActionsPanel` to render prepared download objects instead of creating object URLs during render.
+- Extracted workspace page, selection, dirty-state, message, undo/redo history, command creation, command execution, and reset/load helpers from `App.tsx` into `src/workspace/useWorkspaceState.ts`.
+- Extracted thumbnail state, caching, invalidation, progressive rendering, rotation-aware rendering, copied-page thumbnail reuse, and thumbnail error reporting into `src/pdf/usePdfThumbnails.ts`.
+- Kept PDF loading, IndexedDB persistence, dialogs, preview, merge, export, and split orchestration in `App.tsx` for now.
+
+### Fixed
+
+- Renamed Prettier config files to `.prettierrc.json` and `.prettierignore` so Prettier picks them up automatically.
+- Fixed existing `tsc --noEmit` failures for Vite worker URL imports and `Uint8Array`/`BlobPart` PDF byte handling.
+- Removed a duplicate copy-dialog validation error assignment in `ReorderPanel`.
+- Rotated thumbnails from loaded/saved workspaces are now regenerated from the actual current page rotation instead of relying only on rotation changes after load.
+- Copied/duplicated pages now receive thumbnails through the shared thumbnail hook/cache path instead of ad-hoc copy handling in `App.tsx`.
+
 ## 0.2.0 — Browser-only PDF workspace baseline
 
 ### Added

README

@@ -4,7 +4,7 @@
 
 Current hosted version: <https://pdftools.add-ideas.de>
 
-Current baseline: **v0.2.0 — Browser-only PDF workspace baseline**. See [`CHANGELOG.md`](CHANGELOG.md) for the release notes and milestone history.
+Current release: **v0.3.0 — Selection workspace and maintenance release**. See [`CHANGELOG.md`](CHANGELOG.md) for release notes and milestone history.
 
 The app is a static React/Vite single-page application. There is no backend service, no server-side queue, and no server-side document storage. When hosted correctly, the server only delivers HTML, JavaScript, CSS, and static assets; PDF processing happens in the user's browser.
 
@@ -70,13 +70,14 @@ This makes the project especially useful for self-hosted environments, public-se
 
 - Export the current reordered/rotated/duplicated/deleted workspace as a new PDF.
 - Extract selected pages into a new PDF.
+- Open selected pages as a new active workspace for continued editing.
 - Split the source PDF into single-page PDFs.
 - Merge another PDF by replacing, appending, or inserting it into the current workspace.
 
 ### Keyboard shortcuts
 
 | Shortcut                   | Action                                              |
-| --- | --- |
+| -------------------------- | --------------------------------------------------- |
 | `F1` / `?`                 | Open in-app help and tutorial                       |
 | `Ctrl`/`⌘` + `A`           | Select all pages                                    |
 | `Delete` / `Backspace`     | Delete selected pages after confirmation            |
@@ -115,25 +116,35 @@ browser  <-- HTTPS -->  static web server / reverse proxy  -->  built app assets
 
 There is no application server to operate. Administrators only need to host the built files from `dist/`.
 
-### Build from source
+### Build and test from source
 
 ```bash
 npm ci
+npm run check
+```
+
+`npm run check` runs the main project quality gate:
+
+```bash
+npm run typecheck
+npm run lint
+npm run test
 npm run build
 ```
 
 The production build is written to `dist/`.
 
-To preview the production build locally:
+Useful individual development commands:
 
 ```bash
-npm run preview
+npm run dev           # start the Vite development server
-```
+npm run preview       # preview the production build locally
-
+npm run test          # run tests once
-For development:
+npm run test:watch    # run tests in watch mode
-
+npm run typecheck     # run TypeScript without emitting files
-```bash
+npm run lint          # run ESLint
-npm run dev
+npm run format        # format the project with Prettier
+npm run format:check  # verify Prettier formatting
 ```
 
 ### Static hosting
@@ -216,14 +227,16 @@ The application version shown in the header is defined in `src/version.ts`. The
 The current development baseline is:
 
 ```text
-v0.2.0 — Browser-only PDF workspace baseline
+v0.3.0 — Selection workspace and maintenance release
 ```
 
+This release preserves the browser-only workspace baseline and adds the first post-refactor feature: opening selected pages as a new active workspace. Workspace state, thumbnail handling, generated download URLs, page-grid components, tests, type-checking, linting, and formatting are separated enough to support additional feature work without turning `App.tsx` back into a monolith.
+
 ## Project structure
 
 ```text
 src/
-  App.tsx                         Main application state and orchestration
+  App.tsx                         Main application orchestration and UI wiring
   components/
     ActionDialog.tsx              Reusable confirmation/action dialog
     ActionsPanel.tsx              Export, extract, and split actions
@@ -270,7 +283,7 @@ src/
 - [x] Add command history as a foundation for undo/redo.
 - [x] Add undo/redo.
 - [x] Display undo/redo history with redo entries visually separated.
-- [ ] Extract selection as a new active workspace.
+- [x] Extract selection as a new active workspace.
 - [ ] Reduce undo/redo storage footprint if large documents make snapshots too heavy.
 - [ ] Add grid/list view toggle.
 

eslint.config.mjs

@@ -0,0 +1,55 @@
+import js from '@eslint/js';
+import eslintConfigPrettier from 'eslint-config-prettier';
+import reactHooks from 'eslint-plugin-react-hooks';
+import reactRefresh from 'eslint-plugin-react-refresh';
+import globals from 'globals';
+import tseslint from 'typescript-eslint';
+
+export default tseslint.config(
+  {
+    ignores: ['dist', 'coverage', 'node_modules'],
+  },
+  js.configs.recommended,
+  ...tseslint.configs.recommended,
+  {
+    files: ['**/*.{ts,tsx}'],
+    languageOptions: {
+      ecmaVersion: 2022,
+      sourceType: 'module',
+      globals: {
+        ...globals.browser,
+        ...globals.es2022,
+      },
+    },
+    plugins: {
+      'react-hooks': reactHooks,
+      'react-refresh': reactRefresh,
+    },
+    rules: {
+      ...reactHooks.configs.recommended.rules,
+      'react-refresh/only-export-components': [
+        'warn',
+        { allowConstantExport: true },
+      ],
+      'react-hooks/set-state-in-effect': 'off',
+      '@typescript-eslint/no-unused-vars': [
+        'warn',
+        {
+          argsIgnorePattern: '^_',
+          varsIgnorePattern: '^_',
+          caughtErrorsIgnorePattern: '^_',
+        },
+      ],
+    },
+  },
+  {
+    files: ['*.config.{js,ts}', 'eslint.config.js'],
+    languageOptions: {
+      globals: {
+        ...globals.node,
+        ...globals.es2022,
+      },
+    },
+  },
+  eslintConfigPrettier
+);

package.json

@@ -1,25 +1,45 @@
 {
   "name": "pdf-tools",
-  "version": "0.2.0",
+  "version": "0.3.0",
   "private": true,
+  "type": "module",
   "scripts": {
     "dev": "vite",
     "build": "vite build",
     "preview": "vite preview",
-    "lint": "echo \"no lint configured\""
+    "typecheck": "tsc --noEmit",
+    "lint": "eslint .",
+    "format": "prettier --write .",
+    "format:check": "prettier --check .",
+    "test": "vitest run --environment jsdom",
+    "test:watch": "vitest --environment jsdom",
+    "check": "npm run typecheck && npm run lint && npm run test && npm run build"
   },
   "dependencies": {
     "pdf-lib": "^1.17.1",
-    "pdfjs-dist": "^4.6.82",
+    "pdfjs-dist": "^5.7.284",
-    "react": "^18.3.1",
+    "react": "^19.2.6",
-    "react-dom": "^18.3.1"
+    "react-dom": "^19.2.6"
   },
   "devDependencies": {
-    "@types/react": "^18.3.11",
+    "@eslint/js": "^10.0.1",
-    "@types/react-dom": "^18.3.2",
+    "@testing-library/react": "^16.3.2",
-    "@vitejs/plugin-react-swc": "^3.7.0",
+    "@testing-library/user-event": "^14.6.1",
-    "typescript": "^5.6.3",
+    "@types/node": "^25.8.0",
-    "vite": "^5.4.10"
+    "@types/react": "^19.2.14",
+    "@types/react-dom": "^19.2.3",
+    "@vitejs/plugin-react": "^6.0.2",
+    "eslint": "^10.4.0",
+    "eslint-config-prettier": "^10.1.8",
+    "eslint-plugin-react-hooks": "^7.1.1",
+    "eslint-plugin-react-refresh": "^0.5.2",
+    "globals": "^17.6.0",
+    "jsdom": "^29.1.1",
+    "prettier": "^3.8.3",
+    "typescript": "^6.0.3",
+    "typescript-eslint": "^8.59.3",
+    "vite": "^8.0.13",
+    "vitest": "^4.1.6"
   },
   "description": "Browser-only, self-hostable PDF workbench for page-level PDF operations."
 }

src/components/ActionsPanel.tsx

@@ -1,5 +1,8 @@
 import React from 'react';
-import type { SplitResult } from '../pdf/pdfTypes';
+import type {
+  PdfDownload,
+  SplitPdfDownload,
+} from '../hooks/usePdfGeneratedOutputs';
 
 interface ActionsPanelProps {
   hasPdf: boolean;
@@ -9,13 +12,12 @@ interface ActionsPanelProps {
 
   onSplit: () => void;
   onExtractSelected: () => void;
+  onOpenSelectionAsWorkspace: () => void;
   onExportReordered: () => void;
 
-  splitResults: SplitResult[];
+  splitDownloads: SplitPdfDownload[];
-  subsetDownloadUrl: string | null;
+  subsetDownload: PdfDownload | null;
-  subsetFilename: string | null;
+  exportDownload: PdfDownload | null;
-  exportDownloadUrl: string | null;
-  exportFilename: string | null;
 }
 
 const ActionsPanel: React.FC<ActionsPanelProps> = ({
@@ -24,12 +26,11 @@ const ActionsPanel: React.FC<ActionsPanelProps> = ({
   selectedCount,
   onSplit,
   onExtractSelected,
+  onOpenSelectionAsWorkspace,
   onExportReordered,
-  splitResults,
+  splitDownloads,
-  subsetDownloadUrl,
+  subsetDownload,
-  subsetFilename,
+  exportDownload,
-  exportDownloadUrl,
-  exportFilename,
 }) => {
   const disabled = !hasPdf || isBusy;
 
@@ -38,6 +39,11 @@ const ActionsPanel: React.FC<ActionsPanelProps> = ({
     onExtractSelected();
   };
 
+  const handleOpenSelectionAsWorkspaceClick = () => {
+    if (selectedCount === 0) return;
+    onOpenSelectionAsWorkspace();
+  };
+
   return (
     <div className="card">
       <h2>Tools</h2>
@@ -73,6 +79,20 @@ const ActionsPanel: React.FC<ActionsPanelProps> = ({
           📤 Extract selected ({selectedCount})
         </button>
 
+        <button
+          className="secondary"
+          disabled={disabled || selectedCount === 0}
+          onClick={handleOpenSelectionAsWorkspaceClick}
+          style={{ flex: '1 1 45%' }}
+          title={
+            selectedCount === 0
+              ? 'Select at least one page'
+              : 'Open selected pages as a new unsaved workspace'
+          }
+        >
+          🧩 Open selection as workspace
+        </button>
+
         <button
           className="secondary"
           disabled={disabled}
@@ -83,52 +103,46 @@ const ActionsPanel: React.FC<ActionsPanelProps> = ({
         </button>
       </div>
 
-      {subsetDownloadUrl && subsetFilename && (
+      {subsetDownload && (
         <div style={{ marginTop: '0.5rem', fontSize: '0.9rem' }}>
           <strong>Subset result:</strong>{' '}
           <a
             className="download-link"
-            href={subsetDownloadUrl}
+            href={subsetDownload.url}
-            download={subsetFilename}
+            download={subsetDownload.filename}
           >
-            Download {subsetFilename}
+            Download {subsetDownload.filename}
           </a>
         </div>
       )}
 
-      {exportDownloadUrl && exportFilename && (
+      {exportDownload && (
         <div style={{ marginTop: '0.5rem', fontSize: '0.9rem' }}>
           <strong>Exported document:</strong>{' '}
           <a
             className="download-link"
-            href={exportDownloadUrl}
+            href={exportDownload.url}
-            download={exportFilename}
+            download={exportDownload.filename}
           >
-            Download {exportFilename}
+            Download {exportDownload.filename}
           </a>
         </div>
       )}
 
-      {splitResults.length > 0 && (
+      {splitDownloads.length > 0 && (
         <div style={{ marginTop: '0.75rem', fontSize: '0.9rem' }}>
           <strong>Single-page PDFs:</strong>
           <div>
-            {splitResults.map((r) => {
+            {splitDownloads.map((download) => (
-              const url = URL.createObjectURL(r.blob);
-              return (
               <a
-                  key={r.pageIndex}
+                key={download.id}
                 className="download-link"
-                  href={url}
+                href={download.url}
-                  download={r.filename}
+                download={download.filename}
-                  onClick={() => {
-                    setTimeout(() => URL.revokeObjectURL(url), 5000);
-                  }}
               >
-                  {r.filename}
+                {download.filename}
               </a>
-              );
+            ))}
-            })}
           </div>
         </div>
       )}

src/components/HelpDialog.tsx

@@ -7,13 +7,28 @@ interface HelpDialogProps {
 
 const shortcuts = [
   { keys: 'F1 / ?', description: 'Open this help and tutorial dialog' },
-  { keys: 'Ctrl/⌘ + A', description: 'Select all pages in the current workspace' },
+  {
-  { keys: 'Delete / Backspace', description: 'Delete the selected pages after confirmation' },
+    keys: 'Ctrl/⌘ + A',
-  { keys: 'Esc', description: 'Clear the page selection or close an open dialog' },
+    description: 'Select all pages in the current workspace',
+  },
+  {
+    keys: 'Delete / Backspace',
+    description: 'Delete the selected pages after confirmation',
+  },
+  {
+    keys: 'Esc',
+    description: 'Clear the page selection or close an open dialog',
+  },
   { keys: 'Ctrl/⌘ + Z', description: 'Undo the latest workspace command' },
-  { keys: 'Ctrl/⌘ + Shift + Z', description: 'Redo the next workspace command' },
+  {
+    keys: 'Ctrl/⌘ + Shift + Z',
+    description: 'Redo the next workspace command',
+  },
   { keys: 'Ctrl/⌘ + Y', description: 'Redo the next workspace command' },
-  { keys: '← / → in preview', description: 'Move to the previous or next page in the preview overlay' },
+  {
+    keys: '← / → in preview',
+    description: 'Move to the previous or next page in the preview overlay',
+  },
 ];
 
 const tutorialSteps = [
@@ -30,11 +45,15 @@ const tutorialSteps = [
     body: 'Use the checkbox on a page card to select it. Shift-click extends a range. Dragging a selected page moves the whole selection; the copy controls duplicate selected pages into a chosen slot.',
   },
   {
-    title: '4. Save your workspace or export a PDF',
+    title: '4. Extract selected pages or branch into a new workspace',
+    body: 'Extract selected pages when you only need a download. Open the selection as a new workspace when you want to continue working on that subset.',
+  },
+  {
+    title: '5. Save your workspace or export a PDF',
     body: 'Saving a workspace keeps the current working state in this browser. Exporting creates a new PDF file for download.',
   },
   {
-    title: '5. Use history deliberately',
+    title: '6. Use history deliberately',
     body: 'Each workspace operation is stored as a command with label and timestamp. Undo and redo walk through that command history.',
   },
 ];
@@ -79,8 +98,8 @@ const HelpDialog: React.FC<HelpDialogProps> = ({ open, onClose }) => {
             <h2 id="help-dialog-title">Help & tutorial</h2>
             <p>
               PDF Workbench is a browser-only page workspace. Use it to quickly
-              rearrange, split, merge, rotate, duplicate, and export PDFs without
+              rearrange, split, merge, rotate, duplicate, and export PDFs
-              uploading documents to a server.
+              without uploading documents to a server.
             </p>
           </div>
 
@@ -119,8 +138,8 @@ const HelpDialog: React.FC<HelpDialogProps> = ({ open, onClose }) => {
               ))}
             </div>
             <p className="help-note">
-              Shortcuts are ignored while typing in text fields or other editable
+              Shortcuts are ignored while typing in text fields or other
-              controls.
+              editable controls.
             </p>
           </section>
 

src/components/PagePreviewModal.tsx

@@ -134,6 +134,7 @@ const PagePreviewModal: React.FC<PagePreviewModalProps> = ({
         baseCanvas.height = scaledViewport.height;
 
         const renderTask = page.render({
+          canvas: baseCanvas,
           canvasContext: baseCtx,
           viewport: scaledViewport,
         });

src/components/PageWorkspace/CopyPagesDialog.tsx

@@ -0,0 +1,224 @@
+import React, { useEffect } from 'react';
+
+interface CopyPagesDialogProps {
+  selectedCount: number;
+  pageCount: number;
+  targetPosition: string;
+  error: string | null;
+  onTargetPositionChange: (value: string) => void;
+  onCancel: () => void;
+  onConfirm: (e?: React.FormEvent) => void;
+}
+
+const CopyPagesDialog: React.FC<CopyPagesDialogProps> = ({
+  selectedCount,
+  pageCount,
+  targetPosition,
+  error,
+  onTargetPositionChange,
+  onCancel,
+  onConfirm,
+}) => {
+  useEffect(() => {
+    const handleKeyDown = (e: KeyboardEvent) => {
+      if (e.key === 'Escape') {
+        e.preventDefault();
+        onCancel();
+      }
+    };
+
+    window.addEventListener('keydown', handleKeyDown);
+
+    return () => {
+      window.removeEventListener('keydown', handleKeyDown);
+    };
+  }, [onCancel]);
+
+  return (
+    <div
+      role="dialog"
+      aria-modal="true"
+      aria-labelledby="copy-pages-dialog-title"
+      onPointerDown={(e) => {
+        if (e.target === e.currentTarget) {
+          onCancel();
+        }
+      }}
+      style={{
+        position: 'fixed',
+        inset: 0,
+        zIndex: 60,
+        background: 'rgba(15, 23, 42, 0.55)',
+        display: 'flex',
+        alignItems: 'center',
+        justifyContent: 'center',
+        padding: '1rem',
+      }}
+    >
+      <form
+        onSubmit={onConfirm}
+        style={{
+          width: '100%',
+          maxWidth: '420px',
+          background: 'white',
+          borderRadius: '0.75rem',
+          boxShadow: '0 20px 40px rgba(15, 23, 42, 0.35)',
+          padding: '1rem',
+          display: 'flex',
+          flexDirection: 'column',
+          gap: '0.75rem',
+        }}
+      >
+        <div
+          style={{
+            display: 'flex',
+            justifyContent: 'space-between',
+            alignItems: 'center',
+            gap: '0.75rem',
+          }}
+        >
+          <h2
+            id="copy-pages-dialog-title"
+            style={{
+              margin: 0,
+              fontSize: '1rem',
+            }}
+          >
+            Copy selected pages
+          </h2>
+
+          <button
+            type="button"
+            onClick={onCancel}
+            style={{
+              border: 'none',
+              borderRadius: '999px',
+              width: '1.8rem',
+              height: '1.8rem',
+              background: '#e5e7eb',
+              color: '#111827',
+              cursor: 'pointer',
+              fontSize: '1.1rem',
+              lineHeight: 1,
+              display: 'flex',
+              alignItems: 'center',
+              justifyContent: 'center',
+            }}
+            aria-label="Close copy dialog"
+          >
+            ×
+          </button>
+        </div>
+
+        <p
+          style={{
+            margin: 0,
+            fontSize: '0.9rem',
+            color: '#4b5563',
+          }}
+        >
+          Copy{' '}
+          <strong>
+            {selectedCount === 1
+              ? '1 selected page'
+              : `${selectedCount} selected pages`}
+          </strong>{' '}
+          to a new position.
+        </p>
+
+        <label
+          style={{
+            display: 'flex',
+            flexDirection: 'column',
+            gap: '0.25rem',
+            fontSize: '0.9rem',
+          }}
+        >
+          Insert before position
+          <input
+            type="number"
+            min={1}
+            max={pageCount + 1}
+            value={targetPosition}
+            autoFocus
+            onChange={(e) => onTargetPositionChange(e.target.value)}
+            style={{
+              padding: '0.45rem 0.55rem',
+              borderRadius: '0.5rem',
+              border: '1px solid #d1d5db',
+              fontSize: '0.95rem',
+            }}
+          />
+        </label>
+
+        <div
+          style={{
+            fontSize: '0.8rem',
+            color: '#6b7280',
+            lineHeight: 1.4,
+          }}
+        >
+          <div>1 = before the first page</div>
+          <div>{pageCount + 1} = after the last page</div>
+        </div>
+
+        {error && (
+          <div
+            style={{
+              borderRadius: '0.5rem',
+              background: '#fef2f2',
+              border: '1px solid #fecaca',
+              color: '#b91c1c',
+              padding: '0.5rem',
+              fontSize: '0.85rem',
+            }}
+          >
+            {error}
+          </div>
+        )}
+
+        <div
+          style={{
+            display: 'flex',
+            justifyContent: 'flex-end',
+            gap: '0.5rem',
+            marginTop: '0.25rem',
+          }}
+        >
+          <button
+            type="button"
+            onClick={onCancel}
+            style={{
+              border: 'none',
+              borderRadius: '0.5rem',
+              padding: '0.45rem 0.8rem',
+              background: '#e5e7eb',
+              color: '#111827',
+              cursor: 'pointer',
+              fontSize: '0.9rem',
+            }}
+          >
+            Cancel
+          </button>
+
+          <button
+            type="submit"
+            style={{
+              border: 'none',
+              borderRadius: '0.5rem',
+              padding: '0.45rem 0.8rem',
+              background: '#16a34a',
+              color: 'white',
+              cursor: 'pointer',
+              fontSize: '0.9rem',
+            }}
+          >
+            Copy pages
+          </button>
+        </div>
+      </form>
+    </div>
+  );
+};
+
+export default CopyPagesDialog;

src/components/PageWorkspace/DropIndicator.tsx

@@ -0,0 +1,27 @@
+import React from 'react';
+
+interface DropIndicatorProps {
+  side: 'left' | 'right' | 'end';
+  color: string;
+}
+
+const DropIndicator: React.FC<DropIndicatorProps> = ({ side, color }) => {
+  const isEnd = side === 'end';
+
+  return (
+    <div
+      style={{
+        position: 'absolute',
+        left: side === 'left' ? '-4px' : isEnd ? '8px' : undefined,
+        right: side === 'right' ? '-4px' : undefined,
+        top: '4px',
+        bottom: '4px',
+        width: '3px',
+        borderRadius: '999px',
+        background: color,
+      }}
+    />
+  );
+};
+
+export default DropIndicator;

src/components/PageWorkspace/PageCard.tsx

@@ -0,0 +1,213 @@
+import React from 'react';
+import type { PageRef } from '../../pdf/pdfTypes';
+import DropIndicator from './DropIndicator';
+
+interface PageCardProps {
+  page: PageRef;
+  visualIndex: number;
+  thumbnail?: string;
+  selected: boolean;
+  isDraggingCard: boolean;
+  isBusy: boolean;
+  isCopyDragging: boolean;
+  showLeftLine: boolean;
+  showRightLine: boolean;
+  dropIndicatorColor: string;
+  onDragStart: React.DragEventHandler<HTMLDivElement>;
+  onDragEnd: React.DragEventHandler<HTMLDivElement>;
+  onDragOver: React.DragEventHandler<HTMLDivElement>;
+  onOpenPreview: () => void;
+  onToggleSelect: React.MouseEventHandler<HTMLButtonElement>;
+  onRotateClockwise: () => void;
+  onRotateCounterclockwise: () => void;
+  onDelete: () => void;
+}
+
+const pageActionButtonStyle: React.CSSProperties = {
+  border: 'none',
+  borderRadius: '999px',
+  padding: '0.15rem 0.4rem',
+  fontSize: '0.75rem',
+  cursor: 'pointer',
+};
+
+const PageCard: React.FC<PageCardProps> = ({
+  page,
+  visualIndex,
+  thumbnail,
+  selected,
+  isDraggingCard,
+  isBusy,
+  isCopyDragging,
+  showLeftLine,
+  showRightLine,
+  dropIndicatorColor,
+  onDragStart,
+  onDragEnd,
+  onDragOver,
+  onOpenPreview,
+  onToggleSelect,
+  onRotateClockwise,
+  onRotateCounterclockwise,
+  onDelete,
+}) => {
+  const background = isDraggingCard
+    ? isCopyDragging
+      ? '#dcfce7'
+      : '#dbeafe'
+    : selected
+      ? '#eff6ff'
+      : '#f9fafb';
+
+  return (
+    <div
+      draggable
+      onDragStart={onDragStart}
+      onDragEnd={onDragEnd}
+      onDragOver={onDragOver}
+      onClick={onOpenPreview}
+      style={{
+        position: 'relative',
+        width: '162px',
+        padding: '0.4rem',
+        borderRadius: '0.5rem',
+        border: '1px solid #e5e7eb',
+        background,
+        display: 'flex',
+        flexDirection: 'column',
+        alignItems: 'center',
+        gap: '0.25rem',
+        cursor: isBusy ? 'default' : isCopyDragging ? 'copy' : 'grab',
+        opacity: isBusy ? 0.7 : 1,
+      }}
+    >
+      <button
+        type="button"
+        onClick={onToggleSelect}
+        style={{
+          position: 'absolute',
+          top: '4px',
+          left: '4px',
+          width: '20px',
+          height: '20px',
+          borderRadius: '0.4rem',
+          border: '1px solid #9ca3af',
+          background: selected ? '#2563eb' : 'rgba(255,255,255,0.9)',
+          color: selected ? 'white' : 'transparent',
+          fontSize: '0.8rem',
+          display: 'flex',
+          alignItems: 'center',
+          justifyContent: 'center',
+          padding: 0,
+          cursor: 'pointer',
+        }}
+        title="Select page"
+      >
+        ✓
+      </button>
+
+      {showLeftLine && <DropIndicator side="left" color={dropIndicatorColor} />}
+      {showRightLine && (
+        <DropIndicator side="right" color={dropIndicatorColor} />
+      )}
+
+      <div
+        style={{
+          width: '110px',
+          height: '90px',
+          display: 'flex',
+          alignItems: 'center',
+          justifyContent: 'center',
+        }}
+      >
+        {thumbnail ? (
+          <img
+            src={thumbnail}
+            alt={`Page ${page.sourcePageIndex + 1}`}
+            style={{
+              maxWidth: '100%',
+              maxHeight: '100%',
+              width: 'auto',
+              height: 'auto',
+              objectFit: 'contain',
+              borderRadius: '0.25rem',
+              border: '1px solid #e5e7eb',
+              background: 'white',
+            }}
+          />
+        ) : (
+          <div
+            style={{
+              width: '60px',
+              height: '80px',
+              borderRadius: '0.25rem',
+              border: '1px dashed #d1d5db',
+              background: '#f3f4f6',
+            }}
+          />
+        )}
+      </div>
+
+      <span style={{ fontSize: '0.8rem' }}>
+        Page {page.sourcePageIndex + 1}
+      </span>
+      <span style={{ fontSize: '0.7rem', color: '#6b7280' }}>
+        Pos {visualIndex + 1} · Rot {page.rotation}°
+      </span>
+
+      <div
+        style={{
+          display: 'flex',
+          gap: '0.25rem',
+          marginTop: '0.25rem',
+        }}
+      >
+        <button
+          type="button"
+          onClick={(e) => {
+            e.stopPropagation();
+            onRotateClockwise();
+          }}
+          style={{
+            ...pageActionButtonStyle,
+            background: '#e5e7eb',
+          }}
+        >
+          ↻ 90°
+        </button>
+
+        <button
+          type="button"
+          onClick={(e) => {
+            e.stopPropagation();
+            onRotateCounterclockwise();
+          }}
+          style={{
+            ...pageActionButtonStyle,
+            background: '#e5e7eb',
+          }}
+        >
+          ↺ 90°
+        </button>
+
+        <button
+          type="button"
+          onClick={(e) => {
+            e.stopPropagation();
+            onDelete();
+          }}
+          style={{
+            ...pageActionButtonStyle,
+            background: '#fecaca',
+            color: '#b91c1c',
+          }}
+          title="Remove this page from the exported PDF"
+        >
+          ✕
+        </button>
+      </div>
+    </div>
+  );
+};
+
+export default PageCard;

src/components/PageWorkspace/PageGrid.tsx

@@ -0,0 +1,130 @@
+import React from 'react';
+import type { PageRef } from '../../pdf/pdfTypes';
+import DropIndicator from './DropIndicator';
+import PageCard from './PageCard';
+
+interface PageGridProps {
+  pages: PageRef[];
+  thumbnails: Record<string, string>;
+  selectedPageIds: string[];
+  isBusy: boolean;
+  draggingIndex: number | null;
+  dropIndex: number | null;
+  draggingSelectionActive: boolean;
+  isCopyDragging: boolean;
+  dropIndicatorColor: string;
+  onDragStart: (visualIndex: number) => React.DragEventHandler<HTMLDivElement>;
+  onDragEnd: React.DragEventHandler<HTMLDivElement>;
+  onCardDragOver: (
+    visualIndex: number
+  ) => React.DragEventHandler<HTMLDivElement>;
+  onEndSlotDragOver: React.DragEventHandler<HTMLDivElement>;
+  onDrop: React.DragEventHandler<HTMLDivElement>;
+  onOpenPreview: (pageId: string) => void;
+  onToggleSelect: (
+    pageId: string,
+    visualIndex: number
+  ) => React.MouseEventHandler<HTMLButtonElement>;
+  onRotateClockwise: (pageId: string) => void;
+  onRotateCounterclockwise: (pageId: string) => void;
+  onDelete: (pageId: string) => void;
+}
+
+const PageGrid: React.FC<PageGridProps> = ({
+  pages,
+  thumbnails,
+  selectedPageIds,
+  isBusy,
+  draggingIndex,
+  dropIndex,
+  draggingSelectionActive,
+  isCopyDragging,
+  dropIndicatorColor,
+  onDragStart,
+  onDragEnd,
+  onCardDragOver,
+  onEndSlotDragOver,
+  onDrop,
+  onOpenPreview,
+  onToggleSelect,
+  onRotateClockwise,
+  onRotateCounterclockwise,
+  onDelete,
+}) => {
+  const isSelected = (pageId: string) => selectedPageIds.includes(pageId);
+
+  const showLeftLine = (visualIndex: number) =>
+    dropIndex !== null && dropIndex === visualIndex && draggingIndex !== null;
+
+  const showRightLine = (visualIndex: number) =>
+    dropIndex !== null &&
+    dropIndex === visualIndex + 1 &&
+    draggingIndex !== null;
+
+  const showEndLine = () =>
+    dropIndex !== null && dropIndex === pages.length && draggingIndex !== null;
+
+  return (
+    <div
+      style={{
+        display: 'flex',
+        flexWrap: 'wrap',
+        gap: '0.5rem',
+        alignItems: 'flex-start',
+        marginBottom: '0.75rem',
+      }}
+      onDrop={onDrop}
+    >
+      {pages.map((page, visualIndex) => {
+        const selected = isSelected(page.id);
+        const isDraggingCard =
+          draggingIndex != null &&
+          ((draggingSelectionActive && selected) ||
+            (!draggingSelectionActive && visualIndex === draggingIndex));
+
+        return (
+          <PageCard
+            key={page.id}
+            page={page}
+            visualIndex={visualIndex}
+            thumbnail={thumbnails[page.id]}
+            selected={selected}
+            isDraggingCard={isDraggingCard}
+            isBusy={isBusy}
+            isCopyDragging={isCopyDragging}
+            showLeftLine={showLeftLine(visualIndex)}
+            showRightLine={showRightLine(visualIndex)}
+            dropIndicatorColor={dropIndicatorColor}
+            onDragStart={onDragStart(visualIndex)}
+            onDragEnd={onDragEnd}
+            onDragOver={onCardDragOver(visualIndex)}
+            onOpenPreview={() => onOpenPreview(page.id)}
+            onToggleSelect={onToggleSelect(page.id, visualIndex)}
+            onRotateClockwise={() => onRotateClockwise(page.id)}
+            onRotateCounterclockwise={() => onRotateCounterclockwise(page.id)}
+            onDelete={() => onDelete(page.id)}
+          />
+        );
+      })}
+
+      {pages.length > 0 && (
+        <div
+          onDragOver={onEndSlotDragOver}
+          onDrop={onDrop}
+          style={{
+            width: '20px',
+            height: '120px',
+            position: 'relative',
+            alignSelf: 'stretch',
+          }}
+        >
+          {showEndLine() && (
+            <DropIndicator side="end" color={dropIndicatorColor} />
+          )}
+        </div>
+      )}
+    </div>
+  );
+};
+
+export default PageGrid;

src/components/PageWorkspace/PageSelectionToolbar.tsx

@@ -0,0 +1,112 @@
+import React from 'react';
+
+interface PageSelectionToolbarProps {
+  selectedCount: number;
+  onCopySelected: () => void;
+  onDeleteSelected: () => void;
+  onSelectAll: () => void;
+  onClearSelection: () => void;
+}
+
+const pillButtonStyle: React.CSSProperties = {
+  border: 'none',
+  borderRadius: '999px',
+  padding: '0.15rem 0.6rem',
+  fontSize: '0.8rem',
+};
+
+const PageSelectionToolbar: React.FC<PageSelectionToolbarProps> = ({
+  selectedCount,
+  onCopySelected,
+  onDeleteSelected,
+  onSelectAll,
+  onClearSelection,
+}) => {
+  const hasSelection = selectedCount > 0;
+
+  return (
+    <div
+      style={{
+        display: 'flex',
+        justifyContent: 'space-between',
+        alignItems: 'center',
+        marginBottom: '0.5rem',
+        fontSize: '0.85rem',
+      }}
+    >
+      <span>
+        Selected: <strong>{selectedCount}</strong>
+      </span>
+
+      <div
+        style={{
+          display: 'flex',
+          gap: '0.4rem',
+          flexWrap: 'wrap',
+          justifyContent: 'flex-end',
+        }}
+      >
+        {hasSelection && (
+          <button
+            type="button"
+            onClick={onCopySelected}
+            disabled={!hasSelection}
+            style={{
+              ...pillButtonStyle,
+              background: '#dcfce7',
+              color: '#166534',
+              cursor: 'pointer',
+            }}
+            title="Copy selected pages to another position"
+          >
+            Copy selected
+          </button>
+        )}
+
+        {hasSelection && (
+          <button
+            type="button"
+            onClick={onDeleteSelected}
+            style={{
+              ...pillButtonStyle,
+              background: '#fee2e2',
+              color: '#b91c1c',
+              cursor: 'pointer',
+            }}
+          >
+            Delete selected
+          </button>
+        )}
+
+        <button
+          type="button"
+          onClick={onSelectAll}
+          style={{
+            ...pillButtonStyle,
+            background: '#8dcd8d',
+            color: '#111827',
+            cursor: 'pointer',
+          }}
+        >
+          Select all
+        </button>
+
+        <button
+          type="button"
+          onClick={onClearSelection}
+          disabled={!hasSelection}
+          style={{
+            ...pillButtonStyle,
+            background: '#e5e7eb',
+            color: hasSelection ? '#111827' : '#6b7280',
+            cursor: hasSelection ? 'pointer' : 'default',
+          }}
+        >
+          Clear selection
+        </button>
+      </div>
+    </div>
+  );
+};
+
+export default PageSelectionToolbar;

src/components/ReorderPanel.tsx

@@ -1,5 +1,8 @@
-import React, { useEffect, useState, useRef } from 'react';
+import React, { useRef, useState } from 'react';
 import type { PageRef } from '../pdf/pdfTypes';
+import CopyPagesDialog from './PageWorkspace/CopyPagesDialog';
+import PageGrid from './PageWorkspace/PageGrid';
+import PageSelectionToolbar from './PageWorkspace/PageSelectionToolbar';
 
 interface ReorderPanelProps {
   pages: PageRef[];
@@ -53,8 +56,6 @@ const ReorderPanel: React.FC<ReorderPanelProps> = ({
 
   const dragGhostRef = useRef<HTMLDivElement | null>(null);
 
-  const isSelected = (pageId: string) => selectedPageIds.includes(pageId);
-
   const cleanupDragGhost = () => {
     if (dragGhostRef.current && dragGhostRef.current.parentNode) {
       dragGhostRef.current.parentNode.removeChild(dragGhostRef.current);
@@ -106,6 +107,13 @@ const ReorderPanel: React.FC<ReorderPanelProps> = ({
     e.dataTransfer.setDragImage(ghost, rect.width / 2, rect.height / 2);
   };
 
+  const resetDragState = () => {
+    cleanupDragGhost();
+    setDraggingIndex(null);
+    setDropIndex(null);
+    setIsCopyDragging(false);
+  };
+
   const handleDragStart = (visualIndex: number) => (e: React.DragEvent) => {
     setDraggingIndex(visualIndex);
     setDropIndex(visualIndex);
@@ -122,10 +130,7 @@ const ReorderPanel: React.FC<ReorderPanelProps> = ({
   };
 
   const handleDragEnd = () => {
-    cleanupDragGhost();
+    resetDragState();
-    setDraggingIndex(null);
-    setDropIndex(null);
-    setIsCopyDragging(false);
   };
 
   const handleCardDragOver = (visualIndex: number) => (e: React.DragEvent) => {
@@ -207,35 +212,23 @@ const ReorderPanel: React.FC<ReorderPanelProps> = ({
     setIsCopyDragging(false);
   };
 
-  const handleDeleteClick = (pageId: string) => () => {
+  const handleDeleteClick = (pageId: string) => {
     onDelete(pageId);
     setDraggingIndex(null);
     setDropIndex(null);
   };
 
-  const handleRotateClickClockwise = (pageId: string) => () => {
-    onRotateClockwise(pageId);
-  };
-
-  const handleRotateClickCounterclockwise = (pageId: string) => () => {
-    onRotateCounterclockwise(pageId);
-  };
-
-  const handleCardClick = (pageId: string) => () => {
-    onOpenPreview(pageId);
-  };
-
   const handleCheckboxClick =
     (pageId: string, visualIndex: number) =>
     (e: React.MouseEvent<HTMLButtonElement>) => {
-        e.stopPropagation(); // don't trigger preview
+      e.stopPropagation();
       onToggleSelect(pageId, visualIndex, e);
     };
 
   const handleCopySelectedClick = () => {
     if (selectedPageIds.length === 0) return;
 
-    setCopyTargetPosition(String(pages.length + 1)); // default: after last page
+    setCopyTargetPosition(String(pages.length + 1));
     setCopyDialogError(null);
     setCopyDialogOpen(true);
   };
@@ -245,6 +238,11 @@ const ReorderPanel: React.FC<ReorderPanelProps> = ({
     setCopyDialogError(null);
   };
 
+  const handleCopyTargetPositionChange = (value: string) => {
+    setCopyTargetPosition(value);
+    setCopyDialogError(null);
+  };
+
   const handleCopyDialogConfirm = (e?: React.FormEvent) => {
     e?.preventDefault();
 
@@ -267,23 +265,6 @@ const ReorderPanel: React.FC<ReorderPanelProps> = ({
     setCopyDialogError(null);
   };
 
-  useEffect(() => {
-    if (!copyDialogOpen) return;
-
-    const handleKeyDown = (e: KeyboardEvent) => {
-      if (e.key === 'Escape') {
-        e.preventDefault();
-        handleCopyDialogCancel();
-      }
-    };
-
-    window.addEventListener('keydown', handleKeyDown);
-
-    return () => {
-      window.removeEventListener('keydown', handleKeyDown);
-    };
-  }, [copyDialogOpen]);
-
   if (!hasPdf) {
     return (
       <div className="card">
@@ -293,18 +274,6 @@ const ReorderPanel: React.FC<ReorderPanelProps> = ({
     );
   }
 
-  const showLeftLine = (visualIndex: number) =>
-    dropIndex !== null && dropIndex === visualIndex && draggingIndex !== null;
-
-  const showRightLine = (visualIndex: number) =>
-    dropIndex !== null &&
-    dropIndex === visualIndex + 1 &&
-    draggingIndex !== null;
-
-  const showEndLine = () =>
-    dropIndex !== null && dropIndex === pages.length && draggingIndex !== null;
-
-  // For highlighting the whole selection while dragging it
   const draggingPage = draggingIndex != null ? pages[draggingIndex] : null;
   const draggingSelectionActive =
     draggingPage != null &&
@@ -318,529 +287,53 @@ const ReorderPanel: React.FC<ReorderPanelProps> = ({
         <h2>Pages</h2>
         <p style={{ fontSize: '0.85rem', color: '#6b7280' }}>
           Tap/click a page to preview it. Use the checkbox to select pages
-          (Shift for ranges). Drag to reorder; dragging a selected page moves the
+          (Shift for ranges). Drag to reorder; dragging a selected page moves
-          whole selection. Hold Ctrl/⌘ while dropping to copy instead of move.
+          the whole selection. Hold Ctrl/⌘ while dropping to copy instead of
-          Shortcuts: Ctrl/⌘+A selects all, Delete removes selected pages, Esc clears
+          move. Shortcuts: Ctrl/⌘+A selects all, Delete removes selected pages,
-          selection.
+          Esc clears selection.
         </p>
 
-        <div
+        <PageSelectionToolbar
-          style={{
+          selectedCount={selectedPageIds.length}
-            display: 'flex',
+          onCopySelected={handleCopySelectedClick}
-            justifyContent: 'space-between',
+          onDeleteSelected={onDeleteSelected}
-            alignItems: 'center',
+          onSelectAll={onSelectAll}
-            marginBottom: '0.5rem',
+          onClearSelection={onClearSelection}
-            fontSize: '0.85rem',
+        />
-          }}
-        >
-          <span>
-            Selected: <strong>{selectedPageIds.length}</strong>
-          </span>
-          <div
-            style={{
-              display: 'flex',
-              gap: '0.4rem',
-            }}
-          >
-            {selectedPageIds.length > 0 && (
-              <button
-                type="button"
-                onClick={handleCopySelectedClick}
-                disabled={selectedPageIds.length === 0}
-                style={{
-                  border: 'none',
-                  borderRadius: '999px',
-                  padding: '0.15rem 0.6rem',
-                  fontSize: '0.8rem',
-                  background: '#dcfce7',
-                  color: '#166534',
-                  cursor: 'pointer',
-                }}
-                title={'Copy selected pages to another position'}
-              >
-                Copy selected
-              </button>
-            )}
-            {selectedPageIds.length > 0 && (
-              <button
-                type="button"
-                onClick={onDeleteSelected}
-                style={{
-                  border: 'none',
-                  borderRadius: '999px',
-                  padding: '0.15rem 0.6rem',
-                  fontSize: '0.8rem',
-                  background: '#fee2e2',
-                  color: '#b91c1c',
-                  cursor: 'pointer',
-                }}
-              >
-                Delete selected
-              </button>
-            )}
-            <button
-              type="button"
-              onClick={onSelectAll}
-              style={{
-                border: 'none',
-                borderRadius: '999px',
-                padding: '0.15rem 0.6rem',
-                fontSize: '0.8rem',
-                background: '#8dcd8d',
-                color: '#111827',
-                cursor: 'pointer',
-              }}
-            >
-              Select all
-            </button>
-            <button
-              type="button"
-              onClick={onClearSelection}
-              disabled={selectedPageIds.length === 0}
-              style={{
-                border: 'none',
-                borderRadius: '999px',
-                padding: '0.15rem 0.6rem',
-                fontSize: '0.8rem',
-                background: '#e5e7eb',
-                color: selectedPageIds.length === 0 ? '#6b7280' : '#111827',
-                cursor: selectedPageIds.length === 0 ? 'default' : 'pointer',
-              }}
-            >
-              Clear selection
-            </button>
-          </div>
-        </div>
 
-        <div
+        <PageGrid
-          style={{
+          pages={pages}
-            display: 'flex',
+          thumbnails={thumbnails}
-            flexWrap: 'wrap',
+          selectedPageIds={selectedPageIds}
-            gap: '0.5rem',
+          isBusy={isBusy}
-            alignItems: 'flex-start',
+          draggingIndex={draggingIndex}
-            marginBottom: '0.75rem',
+          dropIndex={dropIndex}
-          }}
+          draggingSelectionActive={draggingSelectionActive}
-          onDrop={handleDrop}
+          isCopyDragging={isCopyDragging}
-        >
+          dropIndicatorColor={dropIndicatorColor}
-          {pages.map((page, visualIndex) => {
+          onDragStart={handleDragStart}
-            const thumb = thumbnails[page.id];
-            const rotation = page.rotation;
-            const selected = isSelected(page.id);
-
-            const isDraggingCard =
-              draggingIndex != null &&
-              ((draggingSelectionActive && selected) ||
-                (!draggingSelectionActive && visualIndex === draggingIndex));
-
-            return (
-              <div
-                key={page.id}
-                draggable
-                onDragStart={handleDragStart(visualIndex)}
           onDragEnd={handleDragEnd}
-                onDragOver={handleCardDragOver(visualIndex)}
+          onCardDragOver={handleCardDragOver}
-                onClick={handleCardClick(page.id)}
+          onEndSlotDragOver={handleEndSlotDragOver}
-                style={{
-                  position: 'relative',
-                  width: '162px',
-                  padding: '0.4rem',
-                  borderRadius: '0.5rem',
-                  border: '1px solid #e5e7eb',
-                  background: isDraggingCard
-                    ? isCopyDragging
-                      ? '#dcfce7'
-                      : '#dbeafe'
-                    : selected
-                    ? '#eff6ff'
-                    : '#f9fafb',
-                  display: 'flex',
-                  flexDirection: 'column',
-                  alignItems: 'center',
-                  gap: '0.25rem',
-                  cursor: isBusy ? 'default' : isCopyDragging ? 'copy' : 'grab',
-                  opacity: isBusy ? 0.7 : 1,
-                }}
-              >
-                {/* selection checkbox */}
-                <button
-                  type="button"
-                  onClick={handleCheckboxClick(page.id, visualIndex)}
-                  style={{
-                    position: 'absolute',
-                    top: '4px',
-                    left: '4px',
-                    width: '20px',
-                    height: '20px',
-                    borderRadius: '0.4rem',
-                    border: '1px solid #9ca3af',
-                    background: selected ? '#2563eb' : 'rgba(255,255,255,0.9)',
-                    color: selected ? 'white' : 'transparent',
-                    fontSize: '0.8rem',
-                    display: 'flex',
-                    alignItems: 'center',
-                    justifyContent: 'center',
-                    padding: 0,
-                    cursor: 'pointer',
-                  }}
-                  title="Select page"
-                >
-                  ✓
-                </button>
-
-                {/* left drop indicator */}
-                {showLeftLine(visualIndex) && (
-                  <div
-                    style={{
-                      position: 'absolute',
-                      left: '-4px',
-                      top: '4px',
-                      bottom: '4px',
-                      width: '3px',
-                      borderRadius: '999px',
-                      background: dropIndicatorColor,
-                    }}
-                  />
-                )}
-
-                {/* right drop indicator */}
-                {showRightLine(visualIndex) && (
-                  <div
-                    style={{
-                      position: 'absolute',
-                      right: '-4px',
-                      top: '4px',
-                      bottom: '4px',
-                      width: '3px',
-                      borderRadius: '999px',
-                      background: dropIndicatorColor,
-                    }}
-                  />
-                )}
-
-                <div
-                  style={{
-                    width: '110px',
-                    height: '90px',
-                    display: 'flex',
-                    alignItems: 'center',
-                    justifyContent: 'center',
-                  }}
-                >
-                  {thumb ? (
-                    <img
-                      src={thumb}
-                      alt={`Page ${page.sourcePageIndex + 1}`}
-                      style={{
-                        maxWidth: '100%',
-                        maxHeight: '100%',
-                        width: 'auto',
-                        height: 'auto',
-                        objectFit: 'contain',
-                        borderRadius: '0.25rem',
-                        border: '1px solid #e5e7eb',
-                        background: 'white',
-                      }}
-                    />
-                  ) : (
-                    <div
-                      style={{
-                        width: '60px',
-                        height: '80px',
-                        borderRadius: '0.25rem',
-                        border: '1px dashed #d1d5db',
-                        background: '#f3f4f6',
-                      }}
-                    />
-                  )}
-                </div>
-
-                <span style={{ fontSize: '0.8rem' }}>Page {page.sourcePageIndex + 1}</span>
-                <span style={{ fontSize: '0.7rem', color: '#6b7280' }}>
-                  Pos {visualIndex + 1} · Rot {rotation}°
-                </span>
-
-                <div
-                  style={{
-                    display: 'flex',
-                    gap: '0.25rem',
-                    marginTop: '0.25rem',
-                  }}
-                >
-                  <button
-                    type="button"
-                    onClick={(e) => {
-                      e.stopPropagation();
-                      handleRotateClickClockwise(page.id)();
-                    }}
-                    style={{
-                      border: 'none',
-                      borderRadius: '999px',
-                      padding: '0.15rem 0.4rem',
-                      fontSize: '0.75rem',
-                      background: '#e5e7eb',
-                      cursor: 'pointer',
-                    }}
-                  >
-                    ↻ 90°
-                  </button>
-                  <button
-                    type="button"
-                    onClick={(e) => {
-                      e.stopPropagation();
-                      handleRotateClickCounterclockwise(page.id)();
-                    }}
-                    style={{
-                      border: 'none',
-                      borderRadius: '999px',
-                      padding: '0.15rem 0.4rem',
-                      fontSize: '0.75rem',
-                      background: '#e5e7eb',
-                      cursor: 'pointer',
-                    }}
-                  >
-                    ↺ 90°
-                  </button>
-                  <button
-                    type="button"
-                    onClick={(e) => {
-                      e.stopPropagation();
-                      handleDeleteClick(page.id)();
-                    }}
-                    style={{
-                      border: 'none',
-                      borderRadius: '999px',
-                      padding: '0.15rem 0.4rem',
-                      fontSize: '0.75rem',
-                      background: '#fecaca',
-                      color: '#b91c1c',
-                      cursor: 'pointer',
-                    }}
-                    title="Remove this page from the exported PDF"
-                  >
-                    ✕
-                  </button>
-                </div>
-              </div>
-            );
-          })}
-
-          {/* end slot for dropping after the last card */}
-          {pages.length > 0 && (
-            <div
-              onDragOver={handleEndSlotDragOver}
           onDrop={handleDrop}
-              style={{
+          onOpenPreview={onOpenPreview}
-                width: '20px',
+          onToggleSelect={handleCheckboxClick}
-                height: '120px',
+          onRotateClockwise={onRotateClockwise}
-                position: 'relative',
+          onRotateCounterclockwise={onRotateCounterclockwise}
-                alignSelf: 'stretch',
+          onDelete={handleDeleteClick}
-              }}
-            >
-              {showEndLine() && (
-                <div
-                  style={{
-                    position: 'absolute',
-                    left: '8px',
-                    top: '4px',
-                    bottom: '4px',
-                    width: '3px',
-                    borderRadius: '999px',
-                    background: dropIndicatorColor,
-                  }}
         />
-              )}
-            </div>
-          )}
-        </div>
       </div>
 
       {copyDialogOpen && (
-        <div
+        <CopyPagesDialog
-          role="dialog"
+          selectedCount={selectedPageIds.length}
-          aria-modal="true"
+          pageCount={pages.length}
-          aria-labelledby="copy-pages-dialog-title"
+          targetPosition={copyTargetPosition}
-          onPointerDown={(e) => {
+          error={copyDialogError}
-            if (e.target === e.currentTarget) {
+          onTargetPositionChange={handleCopyTargetPositionChange}
-              handleCopyDialogCancel();
+          onCancel={handleCopyDialogCancel}
-            }
+          onConfirm={handleCopyDialogConfirm}
-          }}
-          style={{
-            position: 'fixed',
-            inset: 0,
-            zIndex: 60,
-            background: 'rgba(15, 23, 42, 0.55)',
-            display: 'flex',
-            alignItems: 'center',
-            justifyContent: 'center',
-            padding: '1rem',
-          }}
-        >
-          <form
-            onSubmit={handleCopyDialogConfirm}
-            style={{
-              width: '100%',
-              maxWidth: '420px',
-              background: 'white',
-              borderRadius: '0.75rem',
-              boxShadow: '0 20px 40px rgba(15, 23, 42, 0.35)',
-              padding: '1rem',
-              display: 'flex',
-              flexDirection: 'column',
-              gap: '0.75rem',
-            }}
-          >
-            <div
-              style={{
-                display: 'flex',
-                justifyContent: 'space-between',
-                alignItems: 'center',
-                gap: '0.75rem',
-              }}
-            >
-              <h2
-                id="copy-pages-dialog-title"
-                style={{
-                  margin: 0,
-                  fontSize: '1rem',
-                }}
-              >
-                Copy selected pages
-              </h2>
-
-              <button
-                type="button"
-                onClick={handleCopyDialogCancel}
-                style={{
-                  border: 'none',
-                  borderRadius: '999px',
-                  width: '1.8rem',
-                  height: '1.8rem',
-                  background: '#e5e7eb',
-                  color: '#111827',
-                  cursor: 'pointer',
-                  fontSize: '1.1rem',
-                  lineHeight: 1,
-                  display: 'flex',
-                  alignItems: 'center',
-                  justifyContent: 'center',
-                }}
-                aria-label="Close copy dialog"
-              >
-                ×
-              </button>
-            </div>
-
-            <p
-              style={{
-                margin: 0,
-                fontSize: '0.9rem',
-                color: '#4b5563',
-              }}
-            >
-              Copy{' '}
-              <strong>
-                {selectedPageIds.length === 1
-                  ? '1 selected page'
-                  : `${selectedPageIds.length} selected pages`}
-              </strong>{' '}
-              to a new position.
-            </p>
-
-            <label
-              style={{
-                display: 'flex',
-                flexDirection: 'column',
-                gap: '0.25rem',
-                fontSize: '0.9rem',
-              }}
-            >
-              Insert before position
-              <input
-                type="number"
-                min={1}
-                max={pages.length + 1}
-                value={copyTargetPosition}
-                autoFocus
-                onChange={(e) => {
-                  setCopyTargetPosition(e.target.value);
-                  setCopyDialogError(null);
-                }}
-                style={{
-                  padding: '0.45rem 0.55rem',
-                  borderRadius: '0.5rem',
-                  border: '1px solid #d1d5db',
-                  fontSize: '0.95rem',
-                }}
         />
-            </label>
-
-            <div
-              style={{
-                fontSize: '0.8rem',
-                color: '#6b7280',
-                lineHeight: 1.4,
-              }}
-            >
-              <div>1 = before the first page</div>
-              <div>{pages.length + 1} = after the last page</div>
-            </div>
-
-            {copyDialogError && (
-              <div
-                style={{
-                  borderRadius: '0.5rem',
-                  background: '#fef2f2',
-                  border: '1px solid #fecaca',
-                  color: '#b91c1c',
-                  padding: '0.5rem',
-                  fontSize: '0.85rem',
-                }}
-              >
-                {copyDialogError}
-              </div>
-            )}
-
-            <div
-              style={{
-                display: 'flex',
-                justifyContent: 'flex-end',
-                gap: '0.5rem',
-                marginTop: '0.25rem',
-              }}
-            >
-              <button
-                type="button"
-                onClick={handleCopyDialogCancel}
-                style={{
-                  border: 'none',
-                  borderRadius: '0.5rem',
-                  padding: '0.45rem 0.8rem',
-                  background: '#e5e7eb',
-                  color: '#111827',
-                  cursor: 'pointer',
-                  fontSize: '0.9rem',
-                }}
-              >
-                Cancel
-              </button>
-
-              <button
-                type="submit"
-                style={{
-                  border: 'none',
-                  borderRadius: '0.5rem',
-                  padding: '0.45rem 0.8rem',
-                  background: '#16a34a',
-                  color: 'white',
-                  cursor: 'pointer',
-                  fontSize: '0.9rem',
-                }}
-              >
-                Copy pages
-              </button>
-            </div>
-          </form>
-        </div>
       )}
     </>
   );

src/components/WorkspacePanel.tsx

@@ -118,7 +118,9 @@ const WorkspacePanel: React.FC<WorkspacePanelProps> = ({
           className="secondary"
           onClick={onResetWorkspace}
           disabled={!hasPdf || isBusy}
-                    title={!hasPdf ? 'No active workspace' : 'Close the current workspace'}
+          title={
+            !hasPdf ? 'No active workspace' : 'Close the current workspace'
+          }
         >
           Reset workspace
         </button>
@@ -199,8 +201,8 @@ const WorkspacePanel: React.FC<WorkspacePanelProps> = ({
                       {workspace.pdfName} · source pages:{' '}
                       {workspace.sourcePageCount} · workspace pages:{' '}
                       {workspace.workspacePageCount} · undo:{' '}
-                                            {workspace.historyCount} · redo: {workspace.redoCount} · updated{' '}
+                      {workspace.historyCount} · redo: {workspace.redoCount} ·
-                                            {new Date(workspace.updatedAt).toLocaleString()}
+                      updated {new Date(workspace.updatedAt).toLocaleString()}
                     </div>
                   </div>
 
@@ -288,9 +290,7 @@ const WorkspacePanel: React.FC<WorkspacePanelProps> = ({
                 border: '2px solid #166534',
                 width: '100%',
               }}
-                        >
+            ></div>
-                            
-                        </div>
 
             {redoHistory
               .slice()

src/hooks/usePdfGeneratedOutputs.ts

@@ -0,0 +1,128 @@
+import { useCallback, useEffect, useRef, useState } from 'react';
+import type { SplitResult } from '../pdf/pdfTypes';
+
+export interface PdfDownload {
+  id: string;
+  filename: string;
+  url: string;
+}
+
+export interface SplitPdfDownload extends PdfDownload {
+  pageIndex: number;
+}
+
+function revokeDownload(download: PdfDownload | null): void {
+  if (download) {
+    URL.revokeObjectURL(download.url);
+  }
+}
+
+function revokeDownloads(downloads: PdfDownload[]): void {
+  downloads.forEach(revokeDownload);
+}
+
+function createDownload(id: string, filename: string, blob: Blob): PdfDownload {
+  return {
+    id,
+    filename,
+    url: URL.createObjectURL(blob),
+  };
+}
+
+export function usePdfGeneratedOutputs() {
+  const [splitDownloads, setSplitDownloads] = useState<SplitPdfDownload[]>([]);
+  const [subsetDownload, setSubsetDownload] = useState<PdfDownload | null>(
+    null
+  );
+  const [exportDownload, setExportDownload] = useState<PdfDownload | null>(
+    null
+  );
+
+  const splitDownloadsRef = useRef<SplitPdfDownload[]>([]);
+  const subsetDownloadRef = useRef<PdfDownload | null>(null);
+  const exportDownloadRef = useRef<PdfDownload | null>(null);
+
+  const replaceSplitResults = useCallback((results: SplitResult[]) => {
+    const nextDownloads: SplitPdfDownload[] = results.map((result) => ({
+      ...createDownload(
+        `split-${result.pageIndex}-${result.filename}`,
+        result.filename,
+        result.blob
+      ),
+      pageIndex: result.pageIndex,
+    }));
+
+    revokeDownloads(splitDownloadsRef.current);
+    splitDownloadsRef.current = nextDownloads;
+    setSplitDownloads(nextDownloads);
+  }, []);
+
+  const clearSplitResults = useCallback(() => {
+    revokeDownloads(splitDownloadsRef.current);
+    splitDownloadsRef.current = [];
+    setSplitDownloads([]);
+  }, []);
+
+  const replaceSubsetResult = useCallback((blob: Blob, filename: string) => {
+    const nextDownload = createDownload('subset', filename, blob);
+
+    revokeDownload(subsetDownloadRef.current);
+    subsetDownloadRef.current = nextDownload;
+    setSubsetDownload(nextDownload);
+  }, []);
+
+  const clearSubsetResult = useCallback(() => {
+    revokeDownload(subsetDownloadRef.current);
+    subsetDownloadRef.current = null;
+    setSubsetDownload(null);
+  }, []);
+
+  const replaceExportResult = useCallback((blob: Blob, filename: string) => {
+    const nextDownload = createDownload('export', filename, blob);
+
+    revokeDownload(exportDownloadRef.current);
+    exportDownloadRef.current = nextDownload;
+    setExportDownload(nextDownload);
+  }, []);
+
+  const clearExportResult = useCallback(() => {
+    revokeDownload(exportDownloadRef.current);
+    exportDownloadRef.current = null;
+    setExportDownload(null);
+  }, []);
+
+  const clearAllResults = useCallback(() => {
+    revokeDownloads(splitDownloadsRef.current);
+    revokeDownload(subsetDownloadRef.current);
+    revokeDownload(exportDownloadRef.current);
+
+    splitDownloadsRef.current = [];
+    subsetDownloadRef.current = null;
+    exportDownloadRef.current = null;
+
+    setSplitDownloads([]);
+    setSubsetDownload(null);
+    setExportDownload(null);
+  }, []);
+
+  useEffect(() => {
+    return () => {
+      revokeDownloads(splitDownloadsRef.current);
+      revokeDownload(subsetDownloadRef.current);
+      revokeDownload(exportDownloadRef.current);
+    };
+  }, []);
+
+  return {
+    splitDownloads,
+    subsetDownload,
+    exportDownload,
+    replaceSplitResults,
+    clearSplitResults,
+    replaceSubsetResult,
+    clearSubsetResult,
+    replaceExportResult,
+    clearExportResult,
+    clearAllResults,
+  };
+}

src/pdf/pdfService.ts

@@ -5,6 +5,16 @@ function createId() {
   return Math.random().toString(36).slice(2);
 }
 
+function pdfBytesToArrayBuffer(bytes: Uint8Array): ArrayBuffer {
+  const buffer = new ArrayBuffer(bytes.byteLength);
+  new Uint8Array(buffer).set(bytes);
+  return buffer;
+}
+
+function pdfBytesToBlob(bytes: Uint8Array): Blob {
+  return new Blob([pdfBytesToArrayBuffer(bytes)], { type: 'application/pdf' });
+}
+
 export async function loadPdfFromFile(file: File): Promise<PdfFile> {
   const arrayBuffer = await file.arrayBuffer();
   const doc = await PDFDocument.load(arrayBuffer);
@@ -23,8 +33,8 @@ export async function mergePdfFiles(
   newPdf: PdfFile,
   insertAt: number
 ): Promise<PdfFile> {
-  const baseDoc = basePdf.doc ?? await PDFDocument.load(basePdf.arrayBuffer);
+  const baseDoc = basePdf.doc ?? (await PDFDocument.load(basePdf.arrayBuffer));
-  const newDoc = newPdf.doc ?? await PDFDocument.load(newPdf.arrayBuffer);
+  const newDoc = newPdf.doc ?? (await PDFDocument.load(newPdf.arrayBuffer));
 
   const mergedDoc = await PDFDocument.create();
 
@@ -53,8 +63,7 @@ export async function mergePdfFiles(
   }
 
   const bytes = await mergedDoc.save();
-  const buffer = new ArrayBuffer(bytes.byteLength);
+  const buffer = pdfBytesToArrayBuffer(bytes);
-  new Uint8Array(buffer).set(bytes);
 
   const baseName = basePdf.name.replace(/\.pdf$/i, '');
   const newName = newPdf.name.replace(/\.pdf$/i, '');
@@ -99,7 +108,7 @@ export async function splitIntoSinglePages(
     if (modificationDate) newDoc.setModificationDate(modificationDate);
 
     const bytes = await newDoc.save();
-    const blob = new Blob([bytes], { type: 'application/pdf' });
+    const blob = pdfBytesToBlob(bytes);
 
     const base = name.replace(/\.pdf$/i, '');
     const filename = `${base}_page_${String(i + 1).padStart(3, '0')}.pdf`;
@@ -114,10 +123,7 @@ export async function splitIntoSinglePages(
   return results;
 }
 
-export async function extractRange(
+export async function extractRange(pdf: PdfFile, range: Range): Promise<Blob> {
-  pdf: PdfFile,
-  range: Range
-): Promise<Blob> {
   const { doc } = pdf;
   const pageCount = doc.getPageCount();
 
@@ -136,7 +142,7 @@ export async function extractRange(
   copiedPages.forEach((p) => newDoc.addPage(p));
 
   const bytes = await newDoc.save();
-  return new Blob([bytes], { type: 'application/pdf' });
+  return pdfBytesToBlob(bytes);
 }
 
 export async function mergePdfs(pdfs: PdfFile[]): Promise<Blob> {
@@ -150,7 +156,7 @@ export async function mergePdfs(pdfs: PdfFile[]): Promise<Blob> {
   }
 
   const bytes = await newDoc.save();
-  return new Blob([bytes], { type: 'application/pdf' });
+  return pdfBytesToBlob(bytes);
 }
 
 export async function exportPages(
@@ -188,7 +194,7 @@ export async function exportPages(
   });
 
   const bytes = await newDoc.save();
-  return new Blob([bytes], { type: 'application/pdf' });
+  return pdfBytesToBlob(bytes);
 }
 
 export async function exportReordered(

src/pdf/pdfThumbnailService.ts

@@ -37,7 +37,6 @@ interface ThumbnailGenerationOptions {
   onThumbnail?: (update: ThumbnailUpdate) => void;
 }
 
-
 /**
  * Unrotated thumbnails – used e.g. in the Split/Extract view.
  */
@@ -133,7 +132,11 @@ async function generateThumbnailsInternal(
 }
 
 async function renderPageThumbnail(
-  page: Awaited<ReturnType<Awaited<ReturnType<typeof pdfjsLib.getDocument>['promise']>['getPage']>>,
+  page: Awaited<
+    ReturnType<
+      Awaited<ReturnType<typeof pdfjsLib.getDocument>['promise']>['getPage']
+    >
+  >,
   originalIndex: number,
   rotations: RotationsMap,
   maxHeight: number,
@@ -154,6 +157,7 @@ async function renderPageThumbnail(
   baseCanvas.height = scaledViewport.height;
 
   const renderTask = page.render({
+    canvas: baseCanvas,
     canvasContext: baseCtx,
     viewport: scaledViewport,
   });

src/pdf/usePdfThumbnails.ts

@@ -0,0 +1,212 @@
+import { useCallback, useEffect, useRef, useState } from 'react';
+import type { PageRef, PdfFile } from './pdfTypes';
+import { generateThumbnailsWithRotationsProgressive } from './pdfThumbnailService';
+import { normalizeRotation } from '../workspace/useWorkspaceState';
+
+const DEFAULT_MAX_HEIGHT = 150;
+const DEFAULT_MAX_WIDTH = 140;
+const DEFAULT_CONCURRENCY = 3;
+
+interface UsePdfThumbnailsOptions {
+  pdf: PdfFile | null;
+  pages: PageRef[];
+  maxHeight?: number;
+  maxWidth?: number;
+  concurrency?: number;
+  onError?: (message: string, error: unknown) => void;
+}
+
+interface UsePdfThumbnailsResult {
+  thumbnails: Record<string, string>;
+  resetThumbnails: () => void;
+  clearThumbnailCache: () => void;
+}
+
+function thumbnailCacheKey(
+  pdfId: string,
+  sourcePageIndex: number,
+  rotation: number,
+  maxWidth: number,
+  maxHeight: number
+): string {
+  return [
+    pdfId,
+    sourcePageIndex,
+    normalizeRotation(rotation),
+    maxWidth,
+    maxHeight,
+  ].join(':');
+}
+
+function pruneAndMergeThumbnails(
+  previous: Record<string, string>,
+  pages: PageRef[],
+  updates: Record<string, string>
+): Record<string, string> {
+  const pageIds = new Set(pages.map((page) => page.id));
+  const next: Record<string, string> = {};
+
+  for (const [pageId, thumbnail] of Object.entries(previous)) {
+    if (pageIds.has(pageId)) {
+      next[pageId] = thumbnail;
+    }
+  }
+
+  return {
+    ...next,
+    ...updates,
+  };
+}
+
+export function usePdfThumbnails({
+  pdf,
+  pages,
+  maxHeight = DEFAULT_MAX_HEIGHT,
+  maxWidth = DEFAULT_MAX_WIDTH,
+  concurrency = DEFAULT_CONCURRENCY,
+  onError,
+}: UsePdfThumbnailsOptions): UsePdfThumbnailsResult {
+  const [thumbnails, setThumbnails] = useState<Record<string, string>>({});
+  const thumbnailCacheRef = useRef<Map<string, string>>(new Map());
+  const latestPagesRef = useRef<PageRef[]>(pages);
+  const previousPdfIdRef = useRef<string | null>(null);
+
+  useEffect(() => {
+    latestPagesRef.current = pages;
+  }, [pages]);
+
+  const resetThumbnails = useCallback(() => {
+    setThumbnails({});
+  }, []);
+
+  const clearThumbnailCache = useCallback(() => {
+    thumbnailCacheRef.current.clear();
+    setThumbnails({});
+  }, []);
+
+  useEffect(() => {
+    const currentPdfId = pdf?.id ?? null;
+
+    if (!pdf) {
+      previousPdfIdRef.current = null;
+      clearThumbnailCache();
+      return;
+    }
+
+    if (previousPdfIdRef.current !== currentPdfId) {
+      previousPdfIdRef.current = currentPdfId;
+      clearThumbnailCache();
+    }
+  }, [clearThumbnailCache, pdf]);
+
+  useEffect(() => {
+    if (!pdf) return;
+
+    const controller = new AbortController();
+    const cachedUpdates: Record<string, string> = {};
+    const renderGroups = new Map<number, Set<number>>();
+
+    for (const page of pages) {
+      const rotation = normalizeRotation(page.rotation);
+      const cacheKey = thumbnailCacheKey(
+        pdf.id,
+        page.sourcePageIndex,
+        rotation,
+        maxWidth,
+        maxHeight
+      );
+      const cached = thumbnailCacheRef.current.get(cacheKey);
+
+      if (cached) {
+        cachedUpdates[page.id] = cached;
+        continue;
+      }
+
+      const pageIndices = renderGroups.get(rotation) ?? new Set<number>();
+      pageIndices.add(page.sourcePageIndex);
+      renderGroups.set(rotation, pageIndices);
+    }
+
+    setThumbnails((previous) =>
+      pruneAndMergeThumbnails(previous, pages, cachedUpdates)
+    );
+
+    if (renderGroups.size === 0) return;
+
+    const renderMissingThumbnails = async () => {
+      for (const [rotation, pageIndexSet] of renderGroups) {
+        if (controller.signal.aborted) return;
+
+        const pageIndices = Array.from(pageIndexSet);
+        const rotationsBySourcePage: Record<number, number> = {};
+
+        for (const pageIndex of pageIndices) {
+          rotationsBySourcePage[pageIndex] = rotation;
+        }
+
+        await generateThumbnailsWithRotationsProgressive(
+          pdf.arrayBuffer,
+          rotationsBySourcePage,
+          {
+            maxHeight,
+            maxWidth,
+            concurrency: Math.min(concurrency, pageIndices.length),
+            pageIndices,
+            signal: controller.signal,
+            onThumbnail: ({ pageIndex, dataUrl }) => {
+              if (controller.signal.aborted) return;
+
+              thumbnailCacheRef.current.set(
+                thumbnailCacheKey(
+                  pdf.id,
+                  pageIndex,
+                  rotation,
+                  maxWidth,
+                  maxHeight
+                ),
+                dataUrl
+              );
+
+              const updates: Record<string, string> = {};
+
+              for (const page of latestPagesRef.current) {
+                if (
+                  page.sourcePageIndex === pageIndex &&
+                  normalizeRotation(page.rotation) === rotation
+                ) {
+                  updates[page.id] = dataUrl;
+                }
+              }
+
+              if (Object.keys(updates).length === 0) return;
+
+              setThumbnails((previous) =>
+                pruneAndMergeThumbnails(
+                  previous,
+                  latestPagesRef.current,
+                  updates
+                )
+              );
+            },
+          }
+        );
+      }
+    };
+
+    void renderMissingThumbnails().catch((error) => {
+      if (!controller.signal.aborted) {
+        onError?.('Failed to generate thumbnails (see console).', error);
+      }
+    });
+
+    return () => {
+      controller.abort();
+    };
+  }, [concurrency, maxHeight, maxWidth, onError, pages, pdf]);
+
+  return {
+    thumbnails,
+    resetThumbnails,
+    clearThumbnailCache,
+  };
+}

src/styles.css

@@ -6,7 +6,11 @@
 
 body {
   margin: 0;
-  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI',
+  font-family:
+    system-ui,
+    -apple-system,
+    BlinkMacSystemFont,
+    'Segoe UI',
     sans-serif;
   background-color: #f3f4f6;
   color: #111827;

src/version.ts

@@ -1 +1 @@
-export const APP_VERSION = '0.2.0';
+export const APP_VERSION = '0.3.0';

src/vite-env.d.ts

@@ -0,0 +1 @@
+/// <reference types="vite/client" />

src/workspace/useWorkspaceState.test.tsx

@@ -0,0 +1,208 @@
+import React, { forwardRef, useImperativeHandle } from 'react';
+import { act, render } from '@testing-library/react';
+import { describe, expect, it, vi } from 'vitest';
+import type { PageRef } from '../pdf/pdfTypes';
+import type {
+  WorkspaceCommandRecord,
+  WorkspaceCommandState,
+} from './workspaceCommands';
+import { useWorkspaceState } from './useWorkspaceState';
+
+function page(id: string, sourcePageIndex: number, rotation = 0): PageRef {
+  return { id, sourcePageIndex, rotation };
+}
+
+function state(
+  pages: PageRef[],
+  selectedPageIds: string[] = [],
+  lastSelectedVisualIndex: number | null = null
+): WorkspaceCommandState {
+  return { pages, selectedPageIds, lastSelectedVisualIndex };
+}
+
+interface HarnessRef {
+  snapshot: () => {
+    pages: PageRef[];
+    selectedPageIds: string[];
+    lastSelectedVisualIndex: number | null;
+    workspaceDirty: boolean;
+    workspaceMessage: string | null;
+    workspaceHistory: WorkspaceCommandRecord[];
+    redoHistory: WorkspaceCommandRecord[];
+  };
+  replaceWorkspaceState: ReturnType<
+    typeof useWorkspaceState
+  >['replaceWorkspaceState'];
+  getCurrentCommandState: ReturnType<
+    typeof useWorkspaceState
+  >['getCurrentCommandState'];
+  createWorkspaceCommand: ReturnType<
+    typeof useWorkspaceState
+  >['createWorkspaceCommand'];
+  executeWorkspaceCommand: ReturnType<
+    typeof useWorkspaceState
+  >['executeWorkspaceCommand'];
+  handleUndo: ReturnType<typeof useWorkspaceState>['handleUndo'];
+  handleRedo: ReturnType<typeof useWorkspaceState>['handleRedo'];
+}
+
+const Harness = forwardRef<HarnessRef, { onContentChanged?: () => void }>(
+  ({ onContentChanged }, ref) => {
+    const workspace = useWorkspaceState({ onContentChanged });
+
+    useImperativeHandle(ref, () => ({
+      snapshot: () => ({
+        pages: workspace.pages,
+        selectedPageIds: workspace.selectedPageIds,
+        lastSelectedVisualIndex: workspace.lastSelectedVisualIndex,
+        workspaceDirty: workspace.workspaceDirty,
+        workspaceMessage: workspace.workspaceMessage,
+        workspaceHistory: workspace.workspaceHistory,
+        redoHistory: workspace.redoHistory,
+      }),
+      replaceWorkspaceState: workspace.replaceWorkspaceState,
+      getCurrentCommandState: workspace.getCurrentCommandState,
+      createWorkspaceCommand: workspace.createWorkspaceCommand,
+      executeWorkspaceCommand: workspace.executeWorkspaceCommand,
+      handleUndo: workspace.handleUndo,
+      handleRedo: workspace.handleRedo,
+    }));
+
+    return null;
+  }
+);
+
+function renderHarness(onContentChanged = vi.fn()) {
+  const ref = React.createRef<HarnessRef>();
+  render(<Harness ref={ref} onContentChanged={onContentChanged} />);
+
+  if (!ref.current) {
+    throw new Error('Harness ref was not initialized');
+  }
+
+  return { ref, onContentChanged };
+}
+
+describe('useWorkspaceState', () => {
+  it('replaces workspace state from loaded data without marking it dirty', () => {
+    const { ref } = renderHarness();
+    const loadedPages = [page('p1', 0), page('p2', 1, 90)];
+
+    act(() => {
+      ref.current?.replaceWorkspaceState({
+        pages: loadedPages,
+        selectedPageIds: ['p2'],
+        lastSelectedVisualIndex: 1,
+        history: [],
+        redoHistory: [],
+        dirty: false,
+        message: 'Workspace loaded.',
+      });
+    });
+
+    expect(ref.current?.snapshot()).toMatchObject({
+      pages: loadedPages,
+      selectedPageIds: ['p2'],
+      lastSelectedVisualIndex: 1,
+      workspaceDirty: false,
+      workspaceMessage: 'Workspace loaded.',
+      workspaceHistory: [],
+      redoHistory: [],
+    });
+  });
+
+  it('executes commands, stores history, clears redo, and marks content changed', () => {
+    const { ref, onContentChanged } = renderHarness();
+    const before = state([page('p1', 0), page('p2', 1)], ['p1'], 0);
+    const after = state([page('p2', 1), page('p1', 0)], ['p2'], 0);
+
+    act(() => {
+      ref.current?.replaceWorkspaceState({
+        ...before,
+        redoHistory: [
+          {
+            id: 'redo-record',
+            type: 'old-redo',
+            label: 'Old redo',
+            timestamp: '2026-05-17T10:00:00.000Z',
+            payload: { before, after },
+          },
+        ],
+      });
+    });
+
+    act(() => {
+      const command = ref.current?.createWorkspaceCommand({
+        type: 'reorder-pages',
+        label: 'Move page 2 before page 1',
+        before,
+        after,
+      });
+
+      if (!command) throw new Error('Command was not created');
+      ref.current?.executeWorkspaceCommand(command);
+    });
+
+    const snapshot = ref.current?.snapshot();
+    expect(snapshot?.pages).toEqual(after.pages);
+    expect(snapshot?.selectedPageIds).toEqual(['p2']);
+    expect(snapshot?.workspaceDirty).toBe(true);
+    expect(snapshot?.workspaceMessage).toBeNull();
+    expect(snapshot?.workspaceHistory).toHaveLength(1);
+    expect(snapshot?.workspaceHistory[0]).toMatchObject({
+      type: 'reorder-pages',
+      label: 'Move page 2 before page 1',
+    });
+    expect(snapshot?.redoHistory).toHaveLength(0);
+    expect(onContentChanged).toHaveBeenCalledTimes(1);
+  });
+
+  it('undoes and redoes command records in stack order', () => {
+    const { ref, onContentChanged } = renderHarness();
+    const initial = state([page('p1', 0), page('p2', 1)], ['p1'], 0);
+    const reordered = state([page('p2', 1), page('p1', 0)], ['p2'], 0);
+
+    act(() => {
+      ref.current?.replaceWorkspaceState(initial);
+    });
+
+    act(() => {
+      const command = ref.current?.createWorkspaceCommand({
+        type: 'reorder-pages',
+        label: 'Move page',
+        before: initial,
+        after: reordered,
+      });
+
+      if (!command) throw new Error('Command was not created');
+      ref.current?.executeWorkspaceCommand(command);
+    });
+
+    act(() => {
+      ref.current?.handleUndo();
+    });
+
+    expect(ref.current?.snapshot()).toMatchObject({
+      pages: initial.pages,
+      selectedPageIds: initial.selectedPageIds,
+      lastSelectedVisualIndex: initial.lastSelectedVisualIndex,
+      workspaceDirty: true,
+    });
+    expect(ref.current?.snapshot().workspaceHistory).toHaveLength(0);
+    expect(ref.current?.snapshot().redoHistory).toHaveLength(1);
+
+    act(() => {
+      ref.current?.handleRedo();
+    });
+
+    expect(ref.current?.snapshot()).toMatchObject({
+      pages: reordered.pages,
+      selectedPageIds: reordered.selectedPageIds,
+      lastSelectedVisualIndex: reordered.lastSelectedVisualIndex,
+      workspaceDirty: true,
+    });
+    expect(ref.current?.snapshot().workspaceHistory).toHaveLength(1);
+    expect(ref.current?.snapshot().redoHistory).toHaveLength(0);
+    expect(onContentChanged).toHaveBeenCalledTimes(3);
+  });
+});

src/workspace/useWorkspaceState.ts

@@ -0,0 +1,250 @@
+import { useCallback, useRef, useState } from 'react';
+import type { PageRef } from '../pdf/pdfTypes';
+import type {
+  WorkspaceCommand,
+  WorkspaceCommandRecord,
+  WorkspaceCommandState,
+} from './workspaceCommands';
+import {
+  createSnapshotCommand,
+  reviveWorkspaceCommand,
+  toWorkspaceCommandRecord,
+} from './workspaceCommands';
+
+function createId(prefix: string): string {
+  if (typeof crypto !== 'undefined' && crypto.randomUUID) {
+    return crypto.randomUUID();
+  }
+
+  return `${prefix}_${Date.now()}_${Math.random().toString(36).slice(2)}`;
+}
+
+export function createWorkspaceId(): string {
+  return createId('workspace');
+}
+
+export function createPdfId(): string {
+  return createId('pdf');
+}
+
+export function defaultWorkspaceNameFromPdfName(pdfName: string): string {
+  return pdfName.replace(/\.pdf$/i, '') || 'Untitled workspace';
+}
+
+export function createPageRefId(): string {
+  return createId('page');
+}
+
+export function createInitialPageRefs(pageCount: number): PageRef[] {
+  return Array.from({ length: pageCount }, (_, sourcePageIndex) => ({
+    id: createPageRefId(),
+    sourcePageIndex,
+    rotation: 0,
+  }));
+}
+
+export function normalizeRotation(rotation: number | undefined): number {
+  return (((rotation ?? 0) % 360) + 360) % 360;
+}
+
+type SetStateAction<T> = T | ((previous: T) => T);
+
+interface UseWorkspaceStateOptions {
+  onContentChanged?: () => void;
+}
+
+interface ReplaceWorkspaceStateOptions {
+  pages?: PageRef[];
+  selectedPageIds?: string[];
+  lastSelectedVisualIndex?: number | null;
+  history?: WorkspaceCommandRecord[];
+  redoHistory?: WorkspaceCommandRecord[];
+  dirty?: boolean;
+  message?: string | null;
+}
+
+export function useWorkspaceState({
+  onContentChanged,
+}: UseWorkspaceStateOptions = {}) {
+  const [pages, setPagesState] = useState<PageRef[]>([]);
+  const [selectedPageIds, setSelectedPageIdsState] = useState<string[]>([]);
+  const [lastSelectedVisualIndex, setLastSelectedVisualIndexState] = useState<
+    number | null
+  >(null);
+  const [workspaceDirty, setWorkspaceDirty] = useState(false);
+  const [workspaceMessage, setWorkspaceMessage] = useState<string | null>(null);
+  const [workspaceHistory, setWorkspaceHistory] = useState<
+    WorkspaceCommandRecord[]
+  >([]);
+  const [redoHistory, setRedoHistory] = useState<WorkspaceCommandRecord[]>([]);
+
+  const latestPagesRef = useRef<PageRef[]>([]);
+  const selectedPageIdsRef = useRef<string[]>([]);
+  const lastSelectedVisualIndexRef = useRef<number | null>(null);
+
+  const setPages = useCallback((action: SetStateAction<PageRef[]>) => {
+    setPagesState((previous) => {
+      const next = typeof action === 'function' ? action(previous) : action;
+      latestPagesRef.current = next;
+      return next;
+    });
+  }, []);
+
+  const setSelectedPageIds = useCallback((action: SetStateAction<string[]>) => {
+    setSelectedPageIdsState((previous) => {
+      const next = typeof action === 'function' ? action(previous) : action;
+      selectedPageIdsRef.current = next;
+      return next;
+    });
+  }, []);
+
+  const setLastSelectedVisualIndex = useCallback(
+    (action: SetStateAction<number | null>) => {
+      setLastSelectedVisualIndexState((previous) => {
+        const next = typeof action === 'function' ? action(previous) : action;
+        lastSelectedVisualIndexRef.current = next;
+        return next;
+      });
+    },
+    []
+  );
+
+  const getCurrentCommandState = useCallback(
+    (): WorkspaceCommandState => ({
+      pages: latestPagesRef.current,
+      selectedPageIds: selectedPageIdsRef.current,
+      lastSelectedVisualIndex: lastSelectedVisualIndexRef.current,
+    }),
+    []
+  );
+
+  const applyCommandState = useCallback(
+    (state: WorkspaceCommandState) => {
+      setPages(state.pages);
+      setSelectedPageIds(state.selectedPageIds);
+      setLastSelectedVisualIndex(state.lastSelectedVisualIndex);
+    },
+    [setLastSelectedVisualIndex, setPages, setSelectedPageIds]
+  );
+
+  const markWorkspaceChanged = useCallback(() => {
+    setWorkspaceDirty(true);
+    setWorkspaceMessage(null);
+    onContentChanged?.();
+  }, [onContentChanged]);
+
+  const createWorkspaceCommand = useCallback(
+    (params: {
+      type: string;
+      label: string;
+      before: WorkspaceCommandState;
+      after: WorkspaceCommandState;
+      details?: Record<string, unknown>;
+    }): WorkspaceCommand =>
+      createSnapshotCommand({
+        id: createId('command'),
+        type: params.type,
+        label: params.label,
+        before: params.before,
+        after: params.after,
+        details: params.details,
+      }),
+    []
+  );
+
+  const executeWorkspaceCommand = useCallback(
+    (command: WorkspaceCommand) => {
+      const nextState = command.do(getCurrentCommandState());
+
+      applyCommandState(nextState);
+      setWorkspaceHistory((previous) => [
+        ...previous,
+        toWorkspaceCommandRecord(command),
+      ]);
+      setRedoHistory([]);
+      markWorkspaceChanged();
+    },
+    [applyCommandState, getCurrentCommandState, markWorkspaceChanged]
+  );
+
+  const handleUndo = useCallback(() => {
+    const record = workspaceHistory[workspaceHistory.length - 1];
+    if (!record) return;
+
+    const command = reviveWorkspaceCommand(record);
+    const previousState = command.undo(getCurrentCommandState());
+
+    applyCommandState(previousState);
+    setWorkspaceHistory((previous) => previous.slice(0, -1));
+    setRedoHistory((previous) => [...previous, record]);
+    markWorkspaceChanged();
+  }, [
+    applyCommandState,
+    getCurrentCommandState,
+    markWorkspaceChanged,
+    workspaceHistory,
+  ]);
+
+  const handleRedo = useCallback(() => {
+    const record = redoHistory[redoHistory.length - 1];
+    if (!record) return;
+
+    const command = reviveWorkspaceCommand(record);
+    const nextState = command.do(getCurrentCommandState());
+
+    applyCommandState(nextState);
+    setRedoHistory((previous) => previous.slice(0, -1));
+    setWorkspaceHistory((previous) => [...previous, record]);
+    markWorkspaceChanged();
+  }, [
+    applyCommandState,
+    getCurrentCommandState,
+    markWorkspaceChanged,
+    redoHistory,
+  ]);
+
+  const replaceWorkspaceState = useCallback(
+    (state: ReplaceWorkspaceStateOptions = {}) => {
+      setPages(state.pages ?? []);
+      setSelectedPageIds(state.selectedPageIds ?? []);
+      setLastSelectedVisualIndex(state.lastSelectedVisualIndex ?? null);
+      setWorkspaceHistory(state.history ?? []);
+      setRedoHistory(state.redoHistory ?? []);
+      setWorkspaceDirty(state.dirty ?? false);
+      setWorkspaceMessage(state.message ?? null);
+    },
+    [setLastSelectedVisualIndex, setPages, setSelectedPageIds]
+  );
+
+  const resetWorkspaceState = useCallback(() => {
+    replaceWorkspaceState();
+  }, [replaceWorkspaceState]);
+
+  return {
+    pages,
+    setPages,
+    selectedPageIds,
+    setSelectedPageIds,
+    lastSelectedVisualIndex,
+    setLastSelectedVisualIndex,
+    latestPagesRef,
+
+    workspaceDirty,
+    setWorkspaceDirty,
+    workspaceMessage,
+    setWorkspaceMessage,
+    workspaceHistory,
+    setWorkspaceHistory,
+    redoHistory,
+    setRedoHistory,
+
+    getCurrentCommandState,
+    applyCommandState,
+    createWorkspaceCommand,
+    executeWorkspaceCommand,
+    handleUndo,
+    handleRedo,
+    replaceWorkspaceState,
+    resetWorkspaceState,
+  };
+}

src/workspace/workspaceCommands.test.ts

@@ -0,0 +1,105 @@
+import { describe, expect, it } from 'vitest';
+import type { WorkspaceCommandState } from './workspaceCommands';
+import {
+  cloneCommandState,
+  createSnapshotCommand,
+  reviveWorkspaceCommand,
+  toWorkspaceCommandRecord,
+} from './workspaceCommands';
+
+function makeState(pageIds: string[]): WorkspaceCommandState {
+  return {
+    pages: pageIds.map((id, index) => ({
+      id,
+      sourcePageIndex: index,
+      rotation: index * 90,
+    })),
+    selectedPageIds: pageIds.slice(0, 1),
+    lastSelectedVisualIndex: pageIds.length > 0 ? 0 : null,
+  };
+}
+
+describe('workspaceCommands', () => {
+  it('clones command state deeply enough for page and selection changes', () => {
+    const original = makeState(['a', 'b']);
+    const cloned = cloneCommandState(original);
+
+    original.pages[0].rotation = 270;
+    original.selectedPageIds.push('b');
+    original.lastSelectedVisualIndex = 1;
+
+    expect(cloned).toEqual({
+      pages: [
+        { id: 'a', sourcePageIndex: 0, rotation: 0 },
+        { id: 'b', sourcePageIndex: 1, rotation: 90 },
+      ],
+      selectedPageIds: ['a'],
+      lastSelectedVisualIndex: 0,
+    });
+  });
+
+  it('creates snapshot commands that are stable after source states mutate', () => {
+    const before = makeState(['a', 'b']);
+    const after = makeState(['b', 'a']);
+    after.selectedPageIds = ['b'];
+    after.lastSelectedVisualIndex = 0;
+
+    const command = createSnapshotCommand({
+      id: 'cmd-1',
+      type: 'reorder-pages',
+      label: 'Move page',
+      timestamp: '2026-05-17T10:00:00.000Z',
+      before,
+      after,
+      details: { moved: 1 },
+    });
+
+    before.pages.length = 0;
+    after.pages[0].rotation = 180;
+    after.selectedPageIds.push('a');
+
+    expect(command.undo(makeState(['ignored']))).toEqual({
+      pages: [
+        { id: 'a', sourcePageIndex: 0, rotation: 0 },
+        { id: 'b', sourcePageIndex: 1, rotation: 90 },
+      ],
+      selectedPageIds: ['a'],
+      lastSelectedVisualIndex: 0,
+    });
+
+    expect(command.do(makeState(['ignored']))).toEqual({
+      pages: [
+        { id: 'b', sourcePageIndex: 0, rotation: 0 },
+        { id: 'a', sourcePageIndex: 1, rotation: 90 },
+      ],
+      selectedPageIds: ['b'],
+      lastSelectedVisualIndex: 0,
+    });
+  });
+
+  it('round-trips commands through serializable records', () => {
+    const before = makeState(['a', 'b', 'c']);
+    const after: WorkspaceCommandState = {
+      pages: [before.pages[2], before.pages[0], before.pages[1]],
+      selectedPageIds: ['c'],
+      lastSelectedVisualIndex: 0,
+    };
+
+    const command = createSnapshotCommand({
+      id: 'cmd-2',
+      type: 'copy-pages',
+      label: 'Copy pages',
+      timestamp: '2026-05-17T10:05:00.000Z',
+      before,
+      after,
+    });
+
+    const record = toWorkspaceCommandRecord(command);
+    const revived = reviveWorkspaceCommand(record);
+
+    expect(record).not.toHaveProperty('do');
+    expect(record).not.toHaveProperty('undo');
+    expect(revived.do(before)).toEqual(after);
+    expect(revived.undo(after)).toEqual(before);
+  });
+});

src/workspace/workspaceSelection.test.ts

@@ -0,0 +1,39 @@
+import { describe, expect, it } from 'vitest';
+import type { PageRef } from '../pdf/pdfTypes';
+import {
+  createSelectionPdfName,
+  createSelectionWorkspaceName,
+  getSelectedPagesInVisualOrder,
+} from './workspaceSelection';
+
+function page(id: string, sourcePageIndex: number): PageRef {
+  return { id, sourcePageIndex, rotation: 0 };
+}
+
+describe('workspaceSelection', () => {
+  it('returns selected pages in current visual order', () => {
+    const pages = [page('page-3', 2), page('page-1', 0), page('page-2', 1)];
+
+    expect(getSelectedPagesInVisualOrder(pages, ['page-2', 'page-3'])).toEqual([
+      pages[0],
+      pages[2],
+    ]);
+  });
+
+  it('ignores selected ids that are no longer present', () => {
+    const pages = [page('page-1', 0), page('page-2', 1)];
+
+    expect(getSelectedPagesInVisualOrder(pages, ['missing', 'page-2'])).toEqual(
+      [pages[1]]
+    );
+  });
+
+  it('creates readable derived workspace and PDF names', () => {
+    expect(createSelectionWorkspaceName('contract.pdf', 3)).toBe(
+      'contract - 3-page-selection'
+    );
+    expect(createSelectionPdfName('contract.pdf', 1)).toBe(
+      'contract - 1-page-selection.pdf'
+    );
+  });
+});

src/workspace/workspaceSelection.ts

@@ -0,0 +1,31 @@
+import type { PageRef } from '../pdf/pdfTypes';
+
+export function getSelectedPagesInVisualOrder(
+  pages: PageRef[],
+  selectedPageIds: string[]
+): PageRef[] {
+  if (pages.length === 0 || selectedPageIds.length === 0) return [];
+
+  const selectedSet = new Set(selectedPageIds);
+  return pages.filter((page) => selectedSet.has(page.id));
+}
+
+export function createSelectionWorkspaceName(
+  pdfName: string,
+  selectedPageCount: number
+): string {
+  const baseName = pdfName.replace(/\.pdf$/i, '') || 'Untitled';
+  const suffix =
+    selectedPageCount === 1
+      ? '1-page-selection'
+      : `${selectedPageCount}-page-selection`;
+
+  return `${baseName} - ${suffix}`;
+}
+
+export function createSelectionPdfName(
+  pdfName: string,
+  selectedPageCount: number
+): string {
+  return `${createSelectionWorkspaceName(pdfName, selectedPageCount)}.pdf`;
+}

vite.config.ts

@@ -1,5 +1,5 @@
 import { defineConfig } from 'vite';
-import react from '@vitejs/plugin-react-swc';
+import react from '@vitejs/plugin-react';
 
 export default defineConfig({
   plugins: [react()],
@@ -8,4 +8,3 @@ export default defineConfig({
     allowedHosts: ['pdftools.add-ideas.de'], // ← ADD THIS
   },
 });
-