fix(library): ignore current library during folder prescan

Prevent an edited library from treating its own persisted folders as conflicts while preserving overlap warnings for other libraries.

Fixes #1340

server/src/modules/library/dto/prescan-library.dto.ts

@@ -1,6 +1,11 @@
-import { ArrayMinSize, IsArray, IsNotEmpty, IsString, MaxLength } from 'class-validator';
+import { ArrayMinSize, IsArray, IsInt, IsNotEmpty, IsOptional, IsString, MaxLength, Min } from 'class-validator';
 
 export class PrescanLibraryDto {
+  @IsOptional()
+  @IsInt()
+  @Min(1)
+  libraryId?: number;
+
   @IsArray()
   @ArrayMinSize(1)
   @IsString({ each: true })

server/src/modules/library/library.dto.test.ts

@@ -61,9 +61,13 @@ describe('Library DTO validation', () => {
     expect(await hasErrors(plainToInstance(UpdateLibraryAccessDto, { accessLevel: 'owner' }))).toBe(false);
   });
 
-  it('PrescanLibraryDto requires at least one non-empty path', async () => {
+  it('PrescanLibraryDto requires at least one non-empty path and validates an optional library ID', async () => {
     expect(await hasErrors(plainToInstance(PrescanLibraryDto, { paths: [''] }))).toBe(true);
     expect(await hasErrors(plainToInstance(PrescanLibraryDto, { paths: ['/books'] }))).toBe(false);
+    expect(await hasErrors(plainToInstance(PrescanLibraryDto, { paths: ['/books'], libraryId: 12 }))).toBe(false);
+    expect(await hasErrors(plainToInstance(PrescanLibraryDto, { paths: ['/books'], libraryId: 0 }))).toBe(true);
+    expect(await hasErrors(plainToInstance(PrescanLibraryDto, { paths: ['/books'], libraryId: 1.5 }))).toBe(true);
+    expect(await hasErrors(plainToInstance(PrescanLibraryDto, { paths: ['/books'], libraryId: '12' }))).toBe(true);
   });
 
   it('ReorderLibrariesDto validates nested order items', async () => {

server/src/modules/library/library.service.test.ts

@@ -462,7 +462,7 @@ describe('LibraryService', () => {
   });
 
   it('prescan counts primary files recursively and flags overlapping paths', async () => {
-    libraryRepo.findAllFolderPaths.mockResolvedValue([{ path: '/books/existing', libraryName: 'Existing Library' }]);
+    libraryRepo.findAllFolderPaths.mockResolvedValue([{ libraryId: 1, path: '/books/existing', libraryName: 'Existing Library' }]);
 
     mockReaddir.mockImplementation((path: Parameters<typeof readdir>[0]) => {
       if (path === '/books/new') {
@@ -483,6 +483,34 @@ describe('LibraryService', () => {
     expect(result.paths[1]).toEqual(expect.objectContaining({ overlapLibrary: 'Existing Library' }));
   });
 
+  it('prescan ignores persisted folders from the library being edited', async () => {
+    libraryRepo.findAllFolderPaths.mockResolvedValue([
+      { libraryId: 10, path: '/books/audiobooks', libraryName: 'Audiobooks' },
+      { libraryId: 20, path: '/books/ebooks', libraryName: 'eBooks' },
+    ]);
+
+    const result = await service.prescan({ paths: ['/books/audiobooks'], libraryId: 10 });
+
+    expect(result.paths[0]).toEqual({
+      path: '/books/audiobooks',
+      accessible: true,
+      fileCount: 0,
+      overlapLibrary: undefined,
+      error: undefined,
+    });
+  });
+
+  it('prescan still reports a different overlapping library after ignoring the edited library', async () => {
+    libraryRepo.findAllFolderPaths.mockResolvedValue([
+      { libraryId: 10, path: '/books/audiobooks', libraryName: 'Audiobooks' },
+      { libraryId: 20, path: '/books', libraryName: 'All Books' },
+    ]);
+
+    const result = await service.prescan({ paths: ['/books/audiobooks'], libraryId: 10 });
+
+    expect(result.paths[0]).toEqual(expect.objectContaining({ overlapLibrary: 'All Books' }));
+  });
+
   it('prescan reports paths outside the configured browse root without touching the filesystem', async () => {
     libraryRepo.findAllFolderPaths.mockResolvedValue([]);
     pathPolicy.resolveBrowsePath.mockRejectedValue(new ForbiddenException('outside root'));

server/src/modules/library/library.service.ts

@@ -292,6 +292,7 @@ export class LibraryService {
         }
 
         for (const existing of allFolderPaths) {
+          if (dto.libraryId !== undefined && existing.libraryId === dto.libraryId) continue;
           if (pathsOverlap(resolvedInputPath, existing.path)) {
             overlapLibrary = existing.libraryName;
             break;

server/test/library-admin-workflows.e2e-spec.ts

@@ -308,6 +308,25 @@ describe('Library admin workflows (e2e)', { timeout: SCENARIO_TIMEOUT_MS }, () =
         },
       ]);
 
+      const editPrescanResponse = await ctx.app.inject({
+        method: 'POST',
+        url: '/api/v1/libraries/prescan',
+        headers: authHeader(manager.accessToken),
+        payload: { paths: [overlapLibrary.folderPath], libraryId: overlapLibrary.libraryId },
+      });
+
+      expect(editPrescanResponse.statusCode).toBe(201);
+      expect(editPrescanResponse.json()).toEqual({
+        totalFiles: 0,
+        paths: [
+          {
+            path: overlapLibrary.folderPath,
+            accessible: true,
+            fileCount: 0,
+          },
+        ],
+      });
+
       const forbiddenPrescanResponse = await ctx.app.inject({
         method: 'POST',
         url: '/api/v1/libraries/prescan',