feat(import): one Import-file entry + vault notebooks

Phase 3. Import becomes a single top-level action beside "Create
notebook" and the library is vault-backed.

- VaultService.createNotebook copies a picked file into a fresh
  (de-duplicated) notebook folder under the vault; its sidecar lives
  beside it, so annotations travel with the file.
- Home screen: one "Import file" action with a multi-extension picker
  (pdf / docx / pptx); routes to the editor by extension.
- The document list is now a vault scan (folders with a source file),
  not the SQLite documents table — no cache, always correct.
- PPTX soffice detection fix; DOCX convert-on-import is best-effort
  and fails gracefully when LibreOffice is unavailable.

analyze clean, tests green.

lib/l10n/app_en.arb

@@ -5,6 +5,19 @@
   "search": "Search",
   "importPdf": "Import PDF",
   "importPpt": "Import PPT",
+  "importFile": "Import file",
+  "createNotebook": "Create notebook",
+  "noDocumentsYet": "No documents yet — tap Import file",
+  "processingImport": "Importing…",
+  "importFailed": "Couldn't import that file: {error}",
+  "@importFailed": {
+    "placeholders": { "error": { "type": "String" } }
+  },
+  "convertNeedsLibreOffice": "Importing Word documents needs LibreOffice installed. Convert to PDF first, or install LibreOffice.",
+  "unsupportedFileType": "Unsupported file type: {ext}",
+  "@unsupportedFileType": {
+    "placeholders": { "ext": { "type": "String" } }
+  },
   "penCanvasBeta": "Pen Canvas (beta)",
   "newNote": "New Note",
   "open": "Open",

lib/l10n/app_localizations.dart

@@ -128,6 +128,48 @@ abstract class AppLocalizations {
   /// **'Import PPT'**
   String get importPpt;
 
+  /// No description provided for @importFile.
+  ///
+  /// In en, this message translates to:
+  /// **'Import file'**
+  String get importFile;
+
+  /// No description provided for @createNotebook.
+  ///
+  /// In en, this message translates to:
+  /// **'Create notebook'**
+  String get createNotebook;
+
+  /// No description provided for @noDocumentsYet.
+  ///
+  /// In en, this message translates to:
+  /// **'No documents yet — tap Import file'**
+  String get noDocumentsYet;
+
+  /// No description provided for @processingImport.
+  ///
+  /// In en, this message translates to:
+  /// **'Importing…'**
+  String get processingImport;
+
+  /// No description provided for @importFailed.
+  ///
+  /// In en, this message translates to:
+  /// **'Couldn\'t import that file: {error}'**
+  String importFailed(String error);
+
+  /// No description provided for @convertNeedsLibreOffice.
+  ///
+  /// In en, this message translates to:
+  /// **'Importing Word documents needs LibreOffice installed. Convert to PDF first, or install LibreOffice.'**
+  String get convertNeedsLibreOffice;
+
+  /// No description provided for @unsupportedFileType.
+  ///
+  /// In en, this message translates to:
+  /// **'Unsupported file type: {ext}'**
+  String unsupportedFileType(String ext);
+
   /// No description provided for @penCanvasBeta.
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_en.dart

@@ -23,6 +23,32 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get importPpt => 'Import PPT';
 
+  @override
+  String get importFile => 'Import file';
+
+  @override
+  String get createNotebook => 'Create notebook';
+
+  @override
+  String get noDocumentsYet => 'No documents yet — tap Import file';
+
+  @override
+  String get processingImport => 'Importing…';
+
+  @override
+  String importFailed(String error) {
+    return 'Couldn\'t import that file: $error';
+  }
+
+  @override
+  String get convertNeedsLibreOffice =>
+      'Importing Word documents needs LibreOffice installed. Convert to PDF first, or install LibreOffice.';
+
+  @override
+  String unsupportedFileType(String ext) {
+    return 'Unsupported file type: $ext';
+  }
+
   @override
   String get penCanvasBeta => 'Pen Canvas (beta)';
 

lib/l10n/app_localizations_zh.dart

@@ -23,6 +23,32 @@ class AppLocalizationsZh extends AppLocalizations {
   @override
   String get importPpt => '导入 PPT';
 
+  @override
+  String get importFile => '导入文件';
+
+  @override
+  String get createNotebook => '新建笔记本';
+
+  @override
+  String get noDocumentsYet => '暂无文档——点按“导入文件”';
+
+  @override
+  String get processingImport => '正在导入…';
+
+  @override
+  String importFailed(String error) {
+    return '无法导入该文件：$error';
+  }
+
+  @override
+  String get convertNeedsLibreOffice =>
+      '导入 Word 文档需要安装 LibreOffice。请先转换为 PDF，或安装 LibreOffice。';
+
+  @override
+  String unsupportedFileType(String ext) {
+    return '不支持的文件类型：$ext';
+  }
+
   @override
   String get penCanvasBeta => '手写画布（测试版）';
 

lib/l10n/app_zh.arb

@@ -5,6 +5,13 @@
   "search": "搜索",
   "importPdf": "导入 PDF",
   "importPpt": "导入 PPT",
+  "importFile": "导入文件",
+  "createNotebook": "新建笔记本",
+  "noDocumentsYet": "暂无文档——点按“导入文件”",
+  "processingImport": "正在导入…",
+  "importFailed": "无法导入该文件：{error}",
+  "convertNeedsLibreOffice": "导入 Word 文档需要安装 LibreOffice。请先转换为 PDF，或安装 LibreOffice。",
+  "unsupportedFileType": "不支持的文件类型：{ext}",
   "penCanvasBeta": "手写画布（测试版）",
   "newNote": "新建笔记",
   "open": "打开",

lib/providers/document_provider.dart

@@ -1,61 +1,68 @@
+import 'dart:io';
+
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:uuid/uuid.dart';
 
 import '../models/document.dart';
-import '../services/database_service.dart';
-import 'note_provider.dart';
+import '../services/vault_service.dart';
 
-const _uuid = Uuid();
+final vaultServiceProvider = FutureProvider<VaultService>((ref) async {
+  return VaultService.getInstance();
+});
 
 final documentListProvider =
     AsyncNotifierProvider<DocumentListNotifier, List<Document>>(
       DocumentListNotifier.new,
     );
 
+/// The home-screen document list is now sourced from a VAULT SCAN (folders
+/// under the vault root containing a source file + optional sidecar), NOT the
+/// SQLite `documents` table. The sidecar that travels with the file is the
+/// source of truth; there is no SQLite cache for this list (the scan is cheap —
+/// one directory listing — and always correct).
 class DocumentListNotifier extends AsyncNotifier<List<Document>> {
-  Future<DatabaseService> get _db => ref.read(databaseServiceProvider.future);
+  Future<VaultService> get _vault =>
+      ref.read(vaultServiceProvider.future);
 
   @override
   Future<List<Document>> build() async {
-    final db = await _db;
-    return db.getAllDocuments();
+    return _scan();
   }
 
-  /// Reloads documents from the database and publishes the result to [state]
-  /// so the UI rebuilds. Used by pull-to-refresh.
+  Future<List<Document>> _scan() async {
+    final vault = await _vault;
+    final notebooks = await vault.scanNotebooks();
+    return notebooks.map(_toDocument).toList();
+  }
+
+  /// Adapt a scanned [VaultNotebook] into the [Document] shape the home-screen
+  /// tiles already render. The notebook folder path doubles as a stable id.
+  Document _toDocument(VaultNotebook nb) {
+    return Document(
+      id: nb.folderPath,
+      filename: nb.filename,
+      docType: nb.docType,
+      filePath: nb.sourceFilePath,
+      pageCount: 0,
+      createdAt: nb.modified,
+      updatedAt: nb.modified,
+    );
+  }
+
+  /// Re-scan the vault and publish the result. Used by pull-to-refresh and
+  /// after an import.
   Future<void> loadDocuments() async {
     state = const AsyncLoading();
-    state = await AsyncValue.guard(() async {
-      final db = await _db;
-      return db.getAllDocuments();
-    });
-  }
-
-  Future<Document> addDocument({
-    required String filename,
-    required String docType,
-    required String filePath,
-    int pageCount = 0,
-  }) async {
-    final db = await _db;
-    final now = DateTime.now();
-    final document = Document(
-      id: _uuid.v4(),
-      filename: filename,
-      docType: docType,
-      filePath: filePath,
-      pageCount: pageCount,
-      createdAt: now,
-      updatedAt: now,
-    );
-    await db.insertDocument(document);
-    state = AsyncData([document, ...state.value ?? []]);
-    return document;
+    state = await AsyncValue.guard(_scan);
   }
 
+  /// Remove a notebook by deleting its folder (source file + sidecar travel
+  /// together, so removing the folder removes the whole notebook). [id] is the
+  /// notebook folder path produced by [_toDocument].
   Future<void> removeDocument(String id) async {
-    final db = await _db;
-    await db.deleteDocument(id);
+    final dir = Directory(id);
+    if (await dir.exists()) {
+      await dir.delete(recursive: true);
+    }
     final current = state.value ?? [];
     state = AsyncData(current.where((d) => d.id != id).toList());
   }

lib/screens/home_screen.dart

@@ -1,5 +1,7 @@
+import 'package:file_picker/file_picker.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:path/path.dart' as p;
 import '../l10n/app_localizations.dart';
 import '../models/document.dart';
 import '../models/note.dart';
@@ -7,8 +9,8 @@ import '../providers/document_provider.dart';
 import '../providers/note_provider.dart';
 import '../providers/ocr_provider.dart';
 import '../editor/canvas/pen_editor_screen.dart';
-import '../services/pdf_service.dart';
 import '../services/pptx_service.dart';
+import '../services/vault_service.dart';
 import '../editor/canvas/pen_note_screen.dart';
 import '../editor/canvas/pen_slide_screen.dart';
 import 'search_screen.dart';
@@ -50,14 +52,9 @@ class HomeScreen extends ConsumerWidget {
             },
           ),
           IconButton(
-            icon: const Icon(Icons.picture_as_pdf),
-            tooltip: l.importPdf,
-            onPressed: () => _importPdf(context),
-          ),
-          IconButton(
-            icon: const Icon(Icons.slideshow),
-            tooltip: l.importPpt,
-            onPressed: () => _importPptx(context),
+            icon: const Icon(Icons.file_open),
+            tooltip: l.importFile,
+            onPressed: () => _importFile(context, ref),
           ),
           IconButton(
             icon: const Icon(Icons.search),
@@ -163,7 +160,7 @@ class HomeScreen extends ConsumerWidget {
                       ),
                       child: Center(
                         child: Text(
-                          'No documents yet — import a PDF or PPT',
+                          l.noDocumentsYet,
                           style: Theme.of(context).textTheme.bodyMedium
                               ?.copyWith(
                                 color: Theme.of(
@@ -192,43 +189,112 @@ class HomeScreen extends ConsumerWidget {
     }
   }
 
-  Future<void> _importPdf(BuildContext context) async {
-    final pdfService = PdfService();
-    final filePath = await pdfService.pickPdfFile();
-    if (filePath != null && context.mounted) {
-      Navigator.of(context).push(
-        MaterialPageRoute(
-          builder: (_) => PenEditorScreen(pdfPath: filePath),
-        ),
-      );
+  /// Single top-level "Import file" action (sibling of "Create notebook"):
+  /// pick a pdf/docx/pptx/ppt, copy it into a new vault notebook folder, then
+  /// open the IN-VAULT copy in the right editor (routed by extension).
+  Future<void> _importFile(BuildContext context, WidgetRef ref) async {
+    final l = AppLocalizations.of(context);
+    final result = await FilePicker.platform.pickFiles(
+      type: FileType.custom,
+      allowedExtensions: VaultService.importableExtensions.toList(),
+    );
+    final picked = result?.files;
+    if (picked == null || picked.isEmpty) return;
+    final pickedPath = picked.first.path;
+    if (pickedPath == null) return;
+
+    final messenger = context.mounted ? ScaffoldMessenger.of(context) : null;
+    messenger?.showSnackBar(SnackBar(content: Text(l.processingImport)));
+
+    try {
+      final vault = await ref.read(vaultServiceProvider.future);
+      final vaultPath = await vault.createNotebook(pickedPath);
+      // Refresh the documents list so the new notebook shows on return.
+      await ref.read(documentListProvider.notifier).loadDocuments();
+      if (!context.mounted) return;
+      await _openVaultFile(context, ref, vaultPath);
+    } catch (e) {
+      messenger?.showSnackBar(SnackBar(content: Text(l.importFailed('$e'))));
     }
   }
 
-  Future<void> _importPptx(BuildContext context) async {
-    final pptxService = PptxService();
-    final filePath = await pptxService.openPptxFile();
-    if (filePath == null || !context.mounted) return;
+  /// Route an in-vault [filePath] to the correct editor by extension:
+  /// pdf → [PenEditorScreen]; pptx/ppt → [PenSlideScreen]; docx → convert to
+  /// PDF (best-effort, LibreOffice) then open as PDF. Unsupported / failed
+  /// conversions surface a friendly message instead of crashing.
+  Future<void> _openVaultFile(
+    BuildContext context,
+    WidgetRef ref,
+    String filePath,
+  ) async {
+    final l = AppLocalizations.of(context);
+    final ext = p.extension(filePath).replaceFirst('.', '').toLowerCase();
 
-    if (context.mounted) {
-      ScaffoldMessenger.of(
-        context,
-      ).showSnackBar(const SnackBar(content: Text('Processing PPTX...')));
-    }
-
-    final slideImages = await pptxService.convertToImages(filePath);
-    final extractedText = await pptxService.extractText(filePath);
-
-    if (context.mounted) {
-      Navigator.of(context).push(
-        MaterialPageRoute(
-          builder: (_) => PenSlideScreen(
-            filePath: filePath,
-            slideImagePaths: slideImages,
-            extractedText: extractedText.isEmpty ? null : extractedText,
+    switch (ext) {
+      case 'pdf':
+        Navigator.of(context).push(
+          MaterialPageRoute(
+            builder: (_) => PenEditorScreen(pdfPath: filePath),
           ),
-        ),
+        );
+      case 'pptx':
+      case 'ppt':
+        await _openPresentation(context, filePath);
+      case 'docx':
+        final pptxService = PptxService();
+        final pdfPath = await pptxService.convertToPdf(filePath);
+        if (!context.mounted) return;
+        if (pdfPath == null) {
+          ScaffoldMessenger.of(context).showSnackBar(
+            SnackBar(content: Text(l.convertNeedsLibreOffice)),
+          );
+          return;
+        }
+        // The converted PDF lives next to the docx in the notebook folder, so
+        // it becomes the annotatable artifact; re-scan picks it up.
+        await ref.read(documentListProvider.notifier).loadDocuments();
+        if (!context.mounted) return;
+        Navigator.of(context).push(
+          MaterialPageRoute(
+            builder: (_) => PenEditorScreen(pdfPath: pdfPath),
+          ),
+        );
+      default:
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(content: Text(l.unsupportedFileType(ext))),
+        );
+    }
+  }
+
+  Future<void> _openPresentation(
+    BuildContext context,
+    String filePath,
+  ) async {
+    final l = AppLocalizations.of(context);
+    final pptxService = PptxService();
+    if (context.mounted) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(content: Text(l.processingPresentation)),
       );
     }
+    final slideImages = await pptxService.convertToImages(filePath);
+    final extractedText = await pptxService.extractText(filePath);
+    if (!context.mounted) return;
+    if (slideImages.isEmpty) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(content: Text(l.couldNotOpenPresentation)),
+      );
+      return;
+    }
+    Navigator.of(context).push(
+      MaterialPageRoute(
+        builder: (_) => PenSlideScreen(
+          filePath: filePath,
+          slideImagePaths: slideImages,
+          extractedText: extractedText.isEmpty ? null : extractedText,
+        ),
+      ),
+    );
   }
 
   Widget _buildEmptyState(BuildContext context, WidgetRef ref) {
@@ -259,19 +325,13 @@ class HomeScreen extends ConsumerWidget {
           FilledButton.icon(
             onPressed: () => _createAndOpenNote(context, ref),
             icon: const Icon(Icons.add),
-            label: Text(AppLocalizations.of(context).newNote),
+            label: Text(AppLocalizations.of(context).createNotebook),
           ),
           const SizedBox(height: 12),
           OutlinedButton.icon(
-            onPressed: () => _importPdf(context),
-            icon: const Icon(Icons.picture_as_pdf),
-            label: Text(AppLocalizations.of(context).importPdf),
-          ),
-          const SizedBox(height: 12),
-          OutlinedButton.icon(
-            onPressed: () => _importPptx(context),
-            icon: const Icon(Icons.slideshow),
-            label: Text(AppLocalizations.of(context).importPpt),
+            onPressed: () => _importFile(context, ref),
+            icon: const Icon(Icons.file_open),
+            label: Text(AppLocalizations.of(context).importFile),
           ),
         ],
       ),
@@ -512,22 +572,45 @@ class _DocumentTileState extends ConsumerState<_DocumentTile> {
     );
   }
 
-  // [L2] Route by docType: pdf → PenEditorScreen (pen-first), ppt/pptx → PenSlideScreen
+  // Route by docType: pdf → PenEditorScreen (pen-first), ppt/pptx → PenSlideScreen,
+  // docx → best-effort convert-to-PDF then open as PDF.
   Future<void> _openDocument(BuildContext context) async {
     final document = widget.document;
-    final isPdf = document.docType == 'pdf';
+    final l = AppLocalizations.of(context);
 
-    if (isPdf) {
+    if (document.docType == 'pdf') {
       Navigator.of(context).push(
         MaterialPageRoute(
           builder: (_) => PenEditorScreen(pdfPath: document.filePath),
         ),
       );
-    } else {
+      return;
+    }
+
+    if (document.docType == 'docx') {
+      final pdfPath = await PptxService().convertToPdf(document.filePath);
+      if (!mounted) return;
+      if (pdfPath == null) {
+        ScaffoldMessenger.of(this.context).showSnackBar(
+          SnackBar(content: Text(l.convertNeedsLibreOffice)),
+        );
+        return;
+      }
+      await ref.read(documentListProvider.notifier).loadDocuments();
+      if (!mounted) return;
+      Navigator.of(this.context).push(
+        MaterialPageRoute(
+          builder: (_) => PenEditorScreen(pdfPath: pdfPath),
+        ),
+      );
+      return;
+    }
+
+    {
       // PPT/PPTX: convert to images then push PenSlideScreen
       if (mounted) {
         ScaffoldMessenger.of(this.context).showSnackBar(
-          const SnackBar(content: Text('Processing presentation...')),
+          SnackBar(content: Text(l.processingPresentation)),
         );
       }
       final pptxService = PptxService();
@@ -536,7 +619,7 @@ class _DocumentTileState extends ConsumerState<_DocumentTile> {
       if (!mounted) return;
       if (slideImages.isEmpty) {
         ScaffoldMessenger.of(this.context).showSnackBar(
-          const SnackBar(content: Text('Could not open presentation.')),
+          SnackBar(content: Text(l.couldNotOpenPresentation)),
         );
         return;
       }

lib/services/pptx_service.dart

@@ -127,13 +127,15 @@ class PptxService {
   /// Try converting via LibreOffice headless.
   Future<List<String>> _convertViaLibreOffice(String pptxPath) async {
     try {
-      // Check if LibreOffice is available
-      final which = await Process.run('which', ['libreoffice']);
-      if (which.exitCode != 0) return [];
+      // Resolve the LibreOffice binary across platforms. On Windows the binary
+      // is `soffice.exe` (not on PATH for `which`, which is POSIX-only), so we
+      // probe the standard install locations as well — see resolveSoffice().
+      final soffice = await resolveSoffice();
+      if (soffice == null) return [];
 
       final outDir = await _makeTmpDir('pptx_images');
 
-      final result = await Process.run('libreoffice', [
+      final result = await Process.run(soffice, [
         '--headless',
         '--convert-to',
         'png',
@@ -174,6 +176,73 @@ class PptxService {
     }
   }
 
+  /// Resolve the LibreOffice CLI binary for the current platform, or null when
+  /// it cannot be found.
+  ///
+  /// Order:
+  ///   1. Windows: `soffice.exe` at the standard install paths
+  ///      (`C:\Program Files\LibreOffice\program\soffice.exe`, and the 32-bit
+  ///      `Program Files (x86)` variant). The POSIX `which` can't find these.
+  ///   2. POSIX: `which libreoffice`, then `which soffice` (macOS/some distros).
+  ///   3. Otherwise null → callers fall back gracefully.
+  static Future<String?> resolveSoffice() async {
+    if (Platform.isWindows) {
+      const candidates = [
+        r'C:\Program Files\LibreOffice\program\soffice.exe',
+        r'C:\Program Files (x86)\LibreOffice\program\soffice.exe',
+      ];
+      for (final c in candidates) {
+        if (await File(c).exists()) return c;
+      }
+      // Last resort: maybe soffice is on PATH (e.g. a portable install).
+      if (await _whichOk('soffice')) return 'soffice';
+      return null;
+    }
+    if (await _whichOk('libreoffice')) return 'libreoffice';
+    if (await _whichOk('soffice')) return 'soffice';
+    return null;
+  }
+
+  static Future<bool> _whichOk(String cmd) async {
+    try {
+      final r = await Process.run('which', [cmd]);
+      return r.exitCode == 0;
+    } catch (_) {
+      return false;
+    }
+  }
+
+  /// Convert an arbitrary office document (e.g. DOCX) to PDF via LibreOffice
+  /// headless, writing the PDF NEXT TO [sourcePath] (same folder, same
+  /// basename + `.pdf`). Returns the PDF path on success, or null when
+  /// LibreOffice is unavailable or the conversion fails — callers MUST handle
+  /// null and surface a friendly message rather than crash.
+  Future<String?> convertToPdf(String sourcePath) async {
+    final soffice = await resolveSoffice();
+    if (soffice == null) return null;
+
+    final outDir = p.dirname(sourcePath);
+    try {
+      final result = await Process.run(soffice, [
+        '--headless',
+        '--convert-to',
+        'pdf',
+        '--outdir',
+        outDir,
+        sourcePath,
+      ]);
+      if (result.exitCode != 0) return null;
+      final pdfPath = p.join(
+        outDir,
+        '${p.basenameWithoutExtension(sourcePath)}.pdf',
+      );
+      if (await File(pdfPath).exists()) return pdfPath;
+      return null;
+    } catch (_) {
+      return null;
+    }
+  }
+
   /// Generate placeholder slide images when LibreOffice is not available.
   ///
   /// Uses ImageMagick `convert` to create PNG files with slide numbers.

lib/services/vault_service.dart

@@ -1,8 +1,46 @@
 import 'dart:io';
 
 import 'package:flutter/foundation.dart' show visibleForTesting;
+import 'package:path/path.dart' as p;
 import 'package:shared_preferences/shared_preferences.dart';
 
+/// Suffix appended to a source-file path to form its sidecar path. Kept in sync
+/// with [SidecarRepository.kSidecarSuffix]; duplicated here to avoid a layering
+/// dependency from the service onto the editor.
+const String kVaultSidecarSuffix = '.badnote.json';
+
+/// A notebook discovered by scanning the vault: one folder holding a source
+/// file (and, optionally, its sidecar). This is the file-backed source of truth
+/// for the home screen list (the SQLite `documents` table is no longer read).
+class VaultNotebook {
+  const VaultNotebook({
+    required this.folderPath,
+    required this.sourceFilePath,
+    required this.filename,
+    required this.docType,
+    required this.modified,
+    this.hasSidecar = false,
+  });
+
+  /// Absolute path to the notebook folder.
+  final String folderPath;
+
+  /// Absolute path to the annotatable source file inside the folder.
+  final String sourceFilePath;
+
+  /// Source filename including extension, e.g. `Calculus Lecture 3.pdf`.
+  final String filename;
+
+  /// Lowercased extension without the dot: `pdf` / `pptx` / `ppt` / `docx`.
+  final String docType;
+
+  /// Last-modified time of the source file (used for recency sorting).
+  final DateTime modified;
+
+  /// Whether a `<file>.badnote.json` sidecar exists next to the source file.
+  final bool hasSidecar;
+}
+
 /// Records the user-picked vault root folder (an Obsidian-style vault) and
 /// gates app startup behind a valid choice.
 ///
@@ -67,4 +105,115 @@ class VaultService {
     if (path == null || path.isEmpty) return false;
     return Directory(path).exists();
   }
+
+  /// Source-file extensions BadNote can import as notebooks.
+  static const Set<String> importableExtensions = {'pdf', 'docx', 'pptx', 'ppt'};
+
+  /// Create a notebook FOLDER under the vault root, COPY the source file at
+  /// [sourceFilePath] into it, and return the path of the in-vault copy.
+  ///
+  /// The folder name is the sanitized source basename (without extension),
+  /// de-duplicated with a numeric suffix on collision (`Lecture`, `Lecture 2`,
+  /// …). The sidecar (`<file>.badnote.json`) will live next to the copy — the
+  /// [SidecarRepository] keys off the returned path, so nothing else is needed.
+  ///
+  /// Throws [StateError] if no valid vault root is set.
+  Future<String> createNotebook(String sourceFilePath) async {
+    final root = vaultRoot;
+    if (root == null || root.isEmpty) {
+      throw StateError('No vault root is set; cannot create a notebook.');
+    }
+    final source = File(sourceFilePath);
+    final filename = p.basename(sourceFilePath);
+    final baseName = _sanitizeFolderName(p.basenameWithoutExtension(filename));
+
+    final folder = await _uniqueNotebookFolder(root, baseName);
+    await folder.create(recursive: true);
+
+    final destPath = p.join(folder.path, filename);
+    await source.copy(destPath);
+    return destPath;
+  }
+
+  /// Scan the vault root for notebook folders. A notebook is a direct
+  /// subfolder (excluding the hidden `.badnote` metadata folder) that contains
+  /// at least one importable source file. Returns the notebooks sorted by
+  /// source-file mtime, most-recent first. An empty / missing vault yields an
+  /// empty list (never throws).
+  Future<List<VaultNotebook>> scanNotebooks() async {
+    final root = vaultRoot;
+    if (root == null || root.isEmpty) return const [];
+    final dir = Directory(root);
+    if (!await dir.exists()) return const [];
+
+    final notebooks = <VaultNotebook>[];
+    await for (final entity in dir.list(followLinks: false)) {
+      if (entity is! Directory) continue;
+      final folderName = p.basename(entity.path);
+      if (folderName.startsWith('.')) continue; // skip .badnote etc.
+
+      final notebook = await _readNotebookFolder(entity);
+      if (notebook != null) notebooks.add(notebook);
+    }
+
+    notebooks.sort((a, b) => b.modified.compareTo(a.modified));
+    return notebooks;
+  }
+
+  /// Inspect a single notebook folder, returning a [VaultNotebook] when it
+  /// holds an importable source file, else null. Picks the first importable
+  /// file (prefers a `.pdf` so a DOCX→PDF-converted notebook opens as its PDF).
+  Future<VaultNotebook?> _readNotebookFolder(Directory folder) async {
+    File? chosen;
+    String? chosenExt;
+    await for (final entity in folder.list(followLinks: false)) {
+      if (entity is! File) continue;
+      final name = p.basename(entity.path);
+      if (name.endsWith(kVaultSidecarSuffix)) continue;
+      final ext = p.extension(name).replaceFirst('.', '').toLowerCase();
+      if (!importableExtensions.contains(ext)) continue;
+      // Prefer a PDF artifact when present (DOCX-converted notebooks keep both).
+      if (chosen == null || (ext == 'pdf' && chosenExt != 'pdf')) {
+        chosen = entity;
+        chosenExt = ext;
+      }
+    }
+    if (chosen == null || chosenExt == null) return null;
+
+    final stat = await chosen.stat();
+    final sidecar = File('${chosen.path}$kVaultSidecarSuffix');
+    return VaultNotebook(
+      folderPath: folder.path,
+      sourceFilePath: chosen.path,
+      filename: p.basename(chosen.path),
+      docType: chosenExt,
+      modified: stat.modified,
+      hasSidecar: await sidecar.exists(),
+    );
+  }
+
+  /// Find an unused notebook folder under [root] for [baseName], appending a
+  /// ` 2`, ` 3`, … suffix on collision.
+  Future<Directory> _uniqueNotebookFolder(String root, String baseName) async {
+    final safeBase = baseName.isEmpty ? 'Untitled' : baseName;
+    var candidate = Directory(p.join(root, safeBase));
+    var n = 2;
+    while (await candidate.exists()) {
+      candidate = Directory(p.join(root, '$safeBase $n'));
+      n++;
+    }
+    return candidate;
+  }
+
+  /// Sanitize a basename into a safe folder name: strip characters illegal on
+  /// Windows/POSIX (`\ / : * ? " < > |`) and control chars, collapse
+  /// whitespace, and trim trailing dots/spaces (illegal on Windows).
+  static String _sanitizeFolderName(String name) {
+    final cleaned = name
+        .replaceAll(RegExp(r'[\\/:*?"<>|\x00-\x1f]'), ' ')
+        .replaceAll(RegExp(r'\s+'), ' ')
+        .trim()
+        .replaceAll(RegExp(r'[. ]+$'), '');
+    return cleaned;
+  }
 }

test/vault_service_test.dart

@@ -78,4 +78,139 @@ void main() {
     await vault.setVaultRoot('');
     expect(await vault.vaultRootValid(), isFalse);
   });
+
+  group('createNotebook', () {
+    late Directory srcDir;
+
+    setUp(() async {
+      srcDir = await Directory.systemTemp.createTemp('vault_src');
+    });
+
+    tearDown(() async {
+      if (await srcDir.exists()) await srcDir.delete(recursive: true);
+    });
+
+    Future<String> makeSource(String name, [String content = 'pdf-bytes']) async {
+      final f = File('${srcDir.path}${Platform.pathSeparator}$name');
+      await f.writeAsString(content);
+      return f.path;
+    }
+
+    test('creates folder, copies file, returns the in-vault path', () async {
+      final vault = await makeService();
+      await vault.setVaultRoot(tempDir.path);
+      final src = await makeSource('Calculus Lecture 3.pdf', 'hello');
+
+      final vaultPath = await vault.createNotebook(src);
+
+      // Returned path is inside the vault, in a folder named from the file.
+      final expectedFolder =
+          '${tempDir.path}${Platform.pathSeparator}Calculus Lecture 3';
+      expect(Directory(expectedFolder).existsSync(), isTrue);
+      expect(
+        vaultPath,
+        '$expectedFolder${Platform.pathSeparator}Calculus Lecture 3.pdf',
+      );
+      // The file was copied with its contents intact.
+      expect(File(vaultPath).existsSync(), isTrue);
+      expect(File(vaultPath).readAsStringSync(), 'hello');
+      // The original is untouched (copy, not move).
+      expect(File(src).existsSync(), isTrue);
+    });
+
+    test('de-duplicates the folder name on collision', () async {
+      final vault = await makeService();
+      await vault.setVaultRoot(tempDir.path);
+
+      final a = await makeSource('Notes.pdf', 'A');
+      final firstPath = await vault.createNotebook(a);
+      expect(
+        firstPath,
+        '${tempDir.path}${Platform.pathSeparator}Notes${Platform.pathSeparator}Notes.pdf',
+      );
+
+      // Re-import a file with the same basename → suffixed folder.
+      final b = await makeSource('Notes.pdf', 'B');
+      final secondPath = await vault.createNotebook(b);
+      expect(
+        secondPath,
+        '${tempDir.path}${Platform.pathSeparator}Notes 2${Platform.pathSeparator}Notes.pdf',
+      );
+      expect(File(secondPath).readAsStringSync(), 'B');
+      // First copy still intact.
+      expect(File(firstPath).readAsStringSync(), 'A');
+    });
+
+    test('throws when no vault root is set', () async {
+      final vault = await makeService();
+      final src = await makeSource('x.pdf');
+      expect(() => vault.createNotebook(src), throwsStateError);
+    });
+  });
+
+  group('scanNotebooks', () {
+    Future<String> writeFile(String path, [String content = 'x']) async {
+      final f = File(path);
+      await f.create(recursive: true);
+      await f.writeAsString(content);
+      return f.path;
+    }
+
+    test('empty / missing vault yields an empty list', () async {
+      final vault = await makeService();
+      // No root set.
+      expect(await vault.scanNotebooks(), isEmpty);
+      // Root set but empty.
+      await vault.setVaultRoot(tempDir.path);
+      expect(await vault.scanNotebooks(), isEmpty);
+    });
+
+    test('lists notebook folders that contain a source file', () async {
+      final vault = await makeService();
+      await vault.setVaultRoot(tempDir.path);
+      final sep = Platform.pathSeparator;
+
+      // A PDF notebook with a sidecar.
+      await writeFile('${tempDir.path}${sep}Lecture${sep}Lecture.pdf');
+      await writeFile(
+        '${tempDir.path}${sep}Lecture${sep}Lecture.pdf.badnote.json',
+        '{}',
+      );
+      // A PPTX notebook without a sidecar.
+      await writeFile('${tempDir.path}${sep}Deck${sep}Deck.pptx');
+      // A hidden vault-metadata folder is skipped.
+      await writeFile('${tempDir.path}$sep.badnote${sep}vault.json', '{}');
+      // A folder with no importable file is skipped.
+      await writeFile('${tempDir.path}${sep}Empty${sep}readme.txt');
+
+      final notebooks = await vault.scanNotebooks();
+      final byName = {for (final n in notebooks) n.filename: n};
+
+      expect(byName.keys, containsAll(['Lecture.pdf', 'Deck.pptx']));
+      expect(notebooks.length, 2);
+
+      expect(byName['Lecture.pdf']!.docType, 'pdf');
+      expect(byName['Lecture.pdf']!.hasSidecar, isTrue);
+      expect(byName['Deck.pptx']!.docType, 'pptx');
+      expect(byName['Deck.pptx']!.hasSidecar, isFalse);
+    });
+
+    test('a created notebook is discoverable by the scan', () async {
+      final vault = await makeService();
+      await vault.setVaultRoot(tempDir.path);
+      final srcDir = await Directory.systemTemp.createTemp('vault_scan_src');
+      try {
+        final src = '${srcDir.path}${Platform.pathSeparator}Doc.pdf';
+        await File(src).writeAsString('bytes');
+        await vault.createNotebook(src);
+
+        final notebooks = await vault.scanNotebooks();
+        expect(notebooks.length, 1);
+        expect(notebooks.first.filename, 'Doc.pdf');
+        expect(notebooks.first.docType, 'pdf');
+      } finally {
+        await srcDir.delete(recursive: true);
+      }
+    });
+  });
 }