fix(ENG-10424): Fix view files in files section using VOL (#904)

- Ticket: [ENG-10414]
- Feature flag: n/a

## Purpose
Fix view files in files section using VOL

## Summary of Changes
Added { queryParamsHandling: 'preserve' } to two                 
  router.navigate() calls in files.component.ts — one in
  handleRootFolderChange() (provider switching) and one in the          
  invalid-provider fallback effect

Author: Vlad0n20

src/app/features/files/pages/files/files.component.spec.ts

@@ -4,7 +4,7 @@ import { DialogService } from 'primeng/dynamicdialog';
 
 import { signal } from '@angular/core';
 import { ComponentFixture, TestBed } from '@angular/core/testing';
-import { ActivatedRoute } from '@angular/router';
+import { ActivatedRoute, Router } from '@angular/router';
 
 import { SENTRY_TOKEN } from '@core/provider/sentry.provider';
 import { FileUploadDialogComponent } from '@osf/shared/components/file-upload-dialog/file-upload-dialog.component';
@@ -18,8 +18,10 @@ import { CustomConfirmationService } from '@osf/shared/services/custom-confirmat
 import { FilesService } from '@osf/shared/services/files.service';
 import { CurrentResourceSelectors } from '@osf/shared/stores/current-resource';
 import { GoogleFilePickerComponent } from '@shared/components/google-file-picker/google-file-picker.component';
+import { FileLabelModel } from '@shared/models/files/file-label.model';
 
 import { FilesSelectionActionsComponent } from '../../components';
+import { FileProvider } from '../../constants';
 import { FilesSelectors } from '../../store';
 
 import { FilesComponent } from './files.component';
@@ -29,6 +31,8 @@ import { getNodeFilesMappedData } from '@testing/data/files/node.data';
 import { testNode } from '@testing/mocks/base-node.mock';
 import { OSFTestingModule } from '@testing/osf.testing.module';
 import { MockComponentWithSignal } from '@testing/providers/component-provider.mock';
+import { ActivatedRouteMock } from '@testing/providers/route-provider.mock';
+import { provideRouterMock, RouterMockType } from '@testing/providers/router-provider.mock';
 import { provideMockStore } from '@testing/providers/store-provider.mock';
 
 describe('Component: Files', () => {
@@ -188,4 +192,138 @@ describe('Component: Files', () => {
       expect(() => component.updateFilesList()).not.toThrow();
     });
   });
+
+  describe('handleRootFolderChange', () => {
+    it('should preserve view_only query param when switching storage providers', () => {
+      const router = TestBed.inject(Router);
+      const navigateSpy = jest.spyOn(router, 'navigate').mockResolvedValue(true);
+
+      const selectedFolder: FileLabelModel = {
+        label: 'Dropbox',
+        folder: { provider: FileProvider.Dropbox } as any,
+      };
+
+      component.handleRootFolderChange(selectedFolder);
+
+      expect(navigateSpy).toHaveBeenCalledWith([`/${component.resourceId()}/files`, FileProvider.Dropbox], {
+        queryParamsHandling: 'preserve',
+      });
+    });
+  });
+
+  describe('invalid provider fallback effect', () => {
+    let innerComponent: FilesComponent;
+    let innerFixture: ComponentFixture<FilesComponent>;
+    let routerMock: RouterMockType;
+
+    beforeEach(async () => {
+      jest.clearAllMocks();
+      routerMock = {
+        ...TestBed.inject(Router),
+        navigate: jest.fn().mockResolvedValue(true),
+        url: '/abc123/files/unknownprovider?view_only=testtoken',
+      } as RouterMockType;
+
+      await TestBed.configureTestingModule({
+        imports: [
+          FilesComponent,
+          OSFTestingModule,
+          ...MockComponents(
+            FileUploadDialogComponent,
+            FormSelectComponent,
+            GoogleFilePickerComponent,
+            LoadingSpinnerComponent,
+            SearchInputComponent,
+            SubHeaderComponent,
+            ViewOnlyLinkMessageComponent,
+            GoogleFilePickerComponent,
+            FilesSelectionActionsComponent
+          ),
+        ],
+        providers: [
+          FilesService,
+          MockProvider(CustomConfirmationService),
+          DialogService,
+          {
+            provide: SENTRY_TOKEN,
+            useValue: {
+              captureException: jest.fn(),
+              captureMessage: jest.fn(),
+              setUser: jest.fn(),
+            },
+          },
+          {
+            provide: ActivatedRoute,
+            useValue: ActivatedRouteMock.withParams({ fileProvider: 'unknownprovider' }).build(),
+          },
+          provideRouterMock(routerMock),
+          provideMockStore({
+            signals: [
+              {
+                selector: CurrentResourceSelectors.getResourceDetails,
+                value: testNode,
+              },
+              {
+                selector: FilesSelectors.getRootFolders,
+                value: getNodeFilesMappedData(),
+              },
+              {
+                selector: FilesSelectors.getCurrentFolder,
+                value: getNodeFilesMappedData(0),
+              },
+              {
+                selector: FilesSelectors.getConfiguredStorageAddons,
+                value: getConfiguredAddonsMappedData(),
+              },
+              {
+                selector: FilesSelectors.getProvider,
+                value: 'osfstorage',
+              },
+              {
+                selector: FilesSelectors.getStorageSupportedFeatures,
+                value: {
+                  osfstorage: ['AddUpdateFiles', 'DownloadAsZip', 'DeleteFiles', 'CopyInto'],
+                },
+              },
+            ],
+          }),
+        ],
+      })
+        .overrideComponent(FilesComponent, {
+          remove: {
+            imports: [FilesTreeComponent],
+          },
+          add: {
+            imports: [
+              MockComponentWithSignal('osf-files-tree', [
+                'files',
+                'currentFolder',
+                'isLoading',
+                'viewOnly',
+                'resourceId',
+                'provider',
+                'storage',
+                'totalCount',
+                'allowedMenuActions',
+                'supportUpload',
+                'selectedFiles',
+                'scrollHeight',
+              ]),
+            ],
+          },
+        })
+        .compileComponents();
+
+      innerFixture = TestBed.createComponent(FilesComponent);
+      innerComponent = innerFixture.componentInstance;
+      innerFixture.detectChanges();
+    });
+
+    it('should preserve view_only query param when redirecting to osfstorage for invalid provider', () => {
+      expect(routerMock.navigate).toHaveBeenCalledWith(
+        [`/${innerComponent.resourceId()}/files`, FileProvider.OsfStorage],
+        { queryParamsHandling: 'preserve' }
+      );
+    });
+  });
 });

src/app/features/files/pages/files/files.component.ts

@@ -292,7 +292,9 @@ export class FilesComponent {
         const rootFoldersOption = rootFoldersOptions.find((option) => option.folder.provider === providerName);
 
         if (!rootFoldersOption) {
-          this.router.navigate([`/${this.resourceId()}/files`, FileProvider.OsfStorage]);
+          this.router.navigate([`/${this.resourceId()}/files`, FileProvider.OsfStorage], {
+            queryParamsHandling: 'preserve',
+          });
         } else {
           this.currentRootFolder.set({
             label: rootFoldersOption.label,
@@ -688,6 +690,6 @@ export class FilesComponent {
   handleRootFolderChange(selectedFolder: FileLabelModel) {
     const provider = selectedFolder.folder?.provider;
     const resourceId = this.resourceId();
-    this.router.navigate([`/${resourceId}/files`, provider]);
+    this.router.navigate([`/${resourceId}/files`, provider], { queryParamsHandling: 'preserve' });
   }
 }