Fix organizer collisions for nested duplicate track names

src/lib/utils/file-organizer.ts

@@ -298,9 +298,13 @@ export class FileOrganizer {
       // Determine if file renaming should be applied
       const shouldRename = renameConfig?.enabled && renameConfig.template;
       const isMultiFile = audioFiles.length > 1;
+      const duplicateBasenames = this.findDuplicateBasenames(audioFiles);
+      const usedTargetFilenames = new Set<string>();
 
       if (shouldRename) {
         await logger?.info(`File renaming enabled with template: ${renameConfig.template}${isMultiFile ? ` (${audioFiles.length} files, indices will be appended)` : ''}`);
+      } else if (duplicateBasenames.size > 0) {
+        await logger?.info(`Detected ${duplicateBasenames.size} duplicate source filename(s); applying folder-aware naming to avoid collisions`);
       }
 
       // Copy audio files (do NOT delete originals - needed for seeding)
@@ -333,8 +337,13 @@ export class FileOrganizer {
             ext,
             isMultiFile ? i + 1 : undefined,
           );
+          filename = this.makeUniqueFilename(filename, usedTargetFilenames);
         } else {
-          filename = path.basename(audioFile);
+          filename = this.buildSourceAwareFilename(
+            audioFile,
+            duplicateBasenames,
+            usedTargetFilenames
+          );
         }
 
         const targetFilePath = path.join(targetPath, filename);
@@ -628,6 +637,72 @@ export class FileOrganizer {
     );
   }
 
+  private findDuplicateBasenames(files: string[]): Set<string> {
+    const counts = new Map<string, number>();
+
+    for (const file of files) {
+      const basename = path.basename(file);
+      counts.set(basename, (counts.get(basename) || 0) + 1);
+    }
+
+    return new Set(
+      Array.from(counts.entries())
+        .filter(([, count]) => count > 1)
+        .map(([basename]) => basename)
+    );
+  }
+
+  private buildSourceAwareFilename(
+    sourcePath: string,
+    duplicateBasenames: Set<string>,
+    usedFilenames: Set<string>
+  ): string {
+    const basename = path.basename(sourcePath);
+    const ext = path.extname(basename);
+    const stem = path.basename(basename, ext);
+
+    let candidate = basename;
+
+    // Preserve folder context for duplicate track names (e.g. CD1/Track01.mp3,
+    // CD2/Track01.mp3) so each file keeps a unique target name.
+    if (duplicateBasenames.has(basename) && !path.isAbsolute(sourcePath)) {
+      const folder = path.dirname(sourcePath);
+      if (folder !== '.') {
+        const folderPrefix = folder
+          .split(path.sep)
+          .filter(Boolean)
+          .map((segment) => this.sanitizePath(segment))
+          .join('-');
+
+        if (folderPrefix) {
+          candidate = `${folderPrefix}-${stem}${ext}`;
+        }
+      }
+    }
+
+    return this.makeUniqueFilename(candidate, usedFilenames);
+  }
+
+  private makeUniqueFilename(filename: string, usedFilenames: Set<string>): string {
+    if (!usedFilenames.has(filename)) {
+      usedFilenames.add(filename);
+      return filename;
+    }
+
+    const ext = path.extname(filename);
+    const stem = path.basename(filename, ext);
+    let suffix = 2;
+
+    while (true) {
+      const candidate = `${stem} (${suffix})${ext}`;
+      if (!usedFilenames.has(candidate)) {
+        usedFilenames.add(candidate);
+        return candidate;
+      }
+      suffix++;
+    }
+  }
+
   /**
    * Download cover art from URL or copy from local cache
    */

tests/utils/file-organizer.test.ts

@@ -468,6 +468,55 @@ describe('file organizer', () => {
     expect(result.isFile).toBe(false);
   });
 
+  it('keeps nested duplicate track names unique when renaming is disabled', async () => {
+    configState.values.set('metadata_tagging_enabled', 'false');
+
+    const organizer = new FileOrganizer('/media', '/tmp');
+    (organizer as any).findAudiobookFiles = vi.fn().mockResolvedValue({
+      audioFiles: [
+        path.join('CD1', 'Track01.mp3'),
+        path.join('CD1', 'Track02.mp3'),
+        path.join('CD2', 'Track01.mp3'),
+        path.join('CD2', 'Track02.mp3'),
+      ],
+      coverFile: undefined,
+      isFile: false,
+    });
+
+    const sourceRoot = path.normalize('/downloads/book');
+    fsMock.access.mockImplementation(async (filePath: string) => {
+      const normalized = path.normalize(filePath);
+      if (normalized.startsWith(sourceRoot)) return undefined;
+      throw new Error('missing');
+    });
+    fsMock.mkdir.mockResolvedValue(undefined);
+    copyFileMock.copyFile.mockResolvedValue(undefined);
+    fsMock.chmod.mockResolvedValue(undefined);
+
+    const result = await organizer.organize('/downloads/book', {
+      title: 'Book',
+      author: 'Author',
+    }, '{author}/{title}');
+
+    const expectedDir = path.join('/media', 'Author', 'Book');
+    expect(result.success).toBe(true);
+    expect(result.filesMovedCount).toBe(4);
+    expect(result.audioFiles).toEqual([
+      path.join(expectedDir, 'CD1-Track01.mp3'),
+      path.join(expectedDir, 'CD1-Track02.mp3'),
+      path.join(expectedDir, 'CD2-Track01.mp3'),
+      path.join(expectedDir, 'CD2-Track02.mp3'),
+    ]);
+    expect(copyFileMock.copyFile).toHaveBeenCalledWith(
+      path.join('/downloads', 'book', 'CD1', 'Track01.mp3'),
+      path.join(expectedDir, 'CD1-Track01.mp3')
+    );
+    expect(copyFileMock.copyFile).toHaveBeenCalledWith(
+      path.join('/downloads', 'book', 'CD2', 'Track01.mp3'),
+      path.join(expectedDir, 'CD2-Track01.mp3')
+    );
+  });
+
   it('returns no audio files for unsupported single files', async () => {
     const organizer = new FileOrganizer('/media', '/tmp');
     fsMock.stat.mockResolvedValue({ isFile: () => true });