fix: add session storage caching for branding logo and favicon

Problem:
- Logo loader makes multiple 404 HEAD requests on every page load while
  detecting the correct image format (jpg, jpeg, png, gif, webp, svg)
- Favicon update is delayed until cluster config API responds

Solution:
- Cache detected logo format path in session storage to skip format
  detection on subsequent page loads
- Cache favicon in session storage and load it immediately during
  preload phase before React bootstrap starts
- Move favicon update logic from bootstrap to brandingLoader with
  exported updateFavicon function for bootstrap to cache new values

This eliminates redundant network requests and provides immediate
logo and favicon display on subsequent page loads within the same session.

Signed-off-by: Oleksii Orel <oorel@redhat.com>

Author: olexii4

packages/dashboard-frontend/index.html

@@ -18,7 +18,7 @@
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <meta http-equiv="X-UA-Compatible" content="ie=edge">
   <title>Dashboard</title>
-  <link rel="shortcut icon" href="/dashboard/assets/branding/favicon.ico" id="dashboardFavicon">
+  <link rel="shortcut icon" href="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7">
   <link rel="stylesheet" type="text/css" href="/dashboard/assets/branding/branding.css">
   <link rel="manifest" crossorigin="use-credentials" href="/dashboard/assets/branding/manifest.json"/>
 </head>

packages/dashboard-frontend/src/preload/__tests__/brandingLoader.spec.ts

@@ -0,0 +1,282 @@
+/*
+ * Copyright (c) 2018-2025 Red Hat, Inc.
+ * This program and the accompanying materials are made
+ * available under the terms of the Eclipse Public License 2.0
+ * which is available at https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *   Red Hat, Inc. - initial API and implementation
+ */
+
+describe('brandingLoader', () => {
+  // These keys must match the constants in brandingLoader.ts and SessionStorageKey enum
+  const BRANDING_LOGO_PATH_KEY = 'branding-logo-path';
+  const BRANDING_FAVICON_KEY = 'branding-favicon';
+
+  let mockSessionStorage: Record<string, string>;
+  let mockFetch: jest.Mock;
+  let mockImgElement: { src: string };
+  let mockFaviconElement: { setAttribute: jest.Mock };
+  let mockQuerySelector: jest.Mock;
+
+  beforeEach(() => {
+    // Reset mocks
+    mockSessionStorage = {};
+    mockImgElement = { src: '' };
+    mockFaviconElement = { setAttribute: jest.fn() };
+
+    // Mock sessionStorage directly on window
+    Object.defineProperty(window, 'sessionStorage', {
+      value: {
+        getItem: jest.fn((key: string) => mockSessionStorage[key] || null),
+        setItem: jest.fn((key: string, value: string) => {
+          mockSessionStorage[key] = value;
+        }),
+        removeItem: jest.fn((key: string) => {
+          delete mockSessionStorage[key];
+        }),
+      },
+      writable: true,
+    });
+
+    // Mock fetch
+    mockFetch = jest.fn();
+    global.fetch = mockFetch;
+
+    // Mock document.querySelector to return appropriate elements based on selector
+    mockQuerySelector = jest.fn().mockImplementation((selector: string) => {
+      if (selector === '.ide-page-loader-content img') {
+        return mockImgElement;
+      }
+      if (selector === 'link[rel="shortcut icon"]') {
+        return mockFaviconElement;
+      }
+      return null;
+    });
+    Object.defineProperty(document, 'querySelector', {
+      value: mockQuerySelector,
+      writable: true,
+    });
+
+    // Mock document.readyState
+    Object.defineProperty(document, 'readyState', {
+      value: 'complete',
+      writable: true,
+    });
+
+    // Reset modules to reload brandingLoader
+    jest.resetModules();
+  });
+
+  afterEach(() => {
+    jest.clearAllMocks();
+  });
+
+  describe('logo loading with cache', () => {
+    it('should use cached logo path if available', async () => {
+      mockSessionStorage[BRANDING_LOGO_PATH_KEY] = '/dashboard/assets/branding/loader.png';
+
+      // Import module to trigger initialization
+      await import('../brandingLoader');
+
+      // Should not make any fetch requests
+      expect(mockFetch).not.toHaveBeenCalled();
+
+      // Should set the cached path
+      expect(mockImgElement.src).toBe('/dashboard/assets/branding/loader.png');
+    });
+
+    it('should detect format with parallel requests and cache when found', async () => {
+      // Mock fetch to return 404 for jpg, jpeg, png and 200 for gif (and svg)
+      mockFetch.mockImplementation((url: string) => {
+        if (url.includes('loader.gif')) {
+          return Promise.resolve({ ok: true });
+        }
+        if (url.includes('loader.svg')) {
+          return Promise.resolve({ ok: true });
+        }
+        return Promise.resolve({ ok: false });
+      });
+
+      // Import module to trigger initialization
+      await import('../brandingLoader');
+
+      // Wait for async operations
+      await new Promise(resolve => setTimeout(resolve, 50));
+
+      // Should have sent parallel requests for all formats including svg
+      expect(mockFetch).toHaveBeenCalledWith('/dashboard/assets/branding/loader.jpg', {
+        method: 'HEAD',
+      });
+      expect(mockFetch).toHaveBeenCalledWith('/dashboard/assets/branding/loader.jpeg', {
+        method: 'HEAD',
+      });
+      expect(mockFetch).toHaveBeenCalledWith('/dashboard/assets/branding/loader.png', {
+        method: 'HEAD',
+      });
+      expect(mockFetch).toHaveBeenCalledWith('/dashboard/assets/branding/loader.gif', {
+        method: 'HEAD',
+      });
+      expect(mockFetch).toHaveBeenCalledWith('/dashboard/assets/branding/loader.webp', {
+        method: 'HEAD',
+      });
+      expect(mockFetch).toHaveBeenCalledWith('/dashboard/assets/branding/loader.svg', {
+        method: 'HEAD',
+      });
+
+      // Should have cached the successful path (gif comes before svg in priority order)
+      expect(mockSessionStorage[BRANDING_LOGO_PATH_KEY]).toBe(
+        '/dashboard/assets/branding/loader.gif',
+      );
+
+      // Should have set the src
+      expect(mockImgElement.src).toBe('/dashboard/assets/branding/loader.gif');
+    });
+
+    it('should use SVG when no other format is found (all checked in parallel)', async () => {
+      // Mock fetch to return 404 for all formats except svg
+      mockFetch.mockImplementation((url: string) => {
+        if (url.includes('loader.svg')) {
+          return Promise.resolve({ ok: true });
+        }
+        return Promise.resolve({ ok: false });
+      });
+
+      // Import module to trigger initialization
+      await import('../brandingLoader');
+
+      // Wait for async operations
+      await new Promise(resolve => setTimeout(resolve, 50));
+
+      // Should have checked all formats in parallel including SVG
+      expect(mockFetch).toHaveBeenCalledWith('/dashboard/assets/branding/loader.svg', {
+        method: 'HEAD',
+      });
+
+      // Should have cached the SVG path
+      expect(mockSessionStorage[BRANDING_LOGO_PATH_KEY]).toBe(
+        '/dashboard/assets/branding/loader.svg',
+      );
+
+      // Should have set the src to SVG
+      expect(mockImgElement.src).toBe('/dashboard/assets/branding/loader.svg');
+    });
+
+    it('should not make requests when image element is not found', async () => {
+      mockQuerySelector.mockImplementation((selector: string) => {
+        if (selector === 'link[rel="shortcut icon"]') {
+          return mockFaviconElement;
+        }
+        return null;
+      });
+
+      // Import module to trigger initialization
+      await import('../brandingLoader');
+
+      // Wait for async operations
+      await new Promise(resolve => setTimeout(resolve, 50));
+
+      // Should not make any fetch requests for logo
+      expect(mockFetch).not.toHaveBeenCalled();
+    });
+  });
+
+  describe('favicon loading with cache', () => {
+    it('should load cached favicon immediately', async () => {
+      const cachedHref = 'data:image/png;base64,testdata';
+      mockSessionStorage[BRANDING_FAVICON_KEY] = cachedHref;
+
+      // Import module to trigger initialization
+      await import('../brandingLoader');
+
+      // Should have updated favicon element
+      expect(mockFaviconElement.setAttribute).toHaveBeenCalledWith('href', cachedHref);
+    });
+
+    it('should not update favicon if no cache exists', async () => {
+      // Import module to trigger initialization
+      await import('../brandingLoader');
+
+      // Should not have updated favicon element (from cached source)
+      expect(mockFaviconElement.setAttribute).not.toHaveBeenCalled();
+    });
+  });
+
+  describe('updateFavicon export', () => {
+    it('should cache and update favicon when dashboardFavicon is provided', async () => {
+      const { updateFavicon } = await import('../brandingLoader');
+
+      await updateFavicon({ base64data: 'base64data', mediatype: 'image/png' });
+
+      // Should cache the favicon
+      expect(mockSessionStorage[BRANDING_FAVICON_KEY]).toBe('data:image/png;base64,base64data');
+
+      // Should update favicon element
+      expect(mockFaviconElement.setAttribute).toHaveBeenCalledWith(
+        'href',
+        'data:image/png;base64,base64data',
+      );
+    });
+
+    it('should fetch default favicon.ico when dashboardFavicon is undefined', async () => {
+      const mockBlob = new Blob(['test'], { type: 'image/x-icon' });
+      const mockDataUrl = 'data:image/x-icon;base64,dGVzdA==';
+
+      mockFetch.mockResolvedValue({
+        ok: true,
+        blob: () => Promise.resolve(mockBlob),
+      });
+
+      // Mock FileReader
+      const mockFileReader = {
+        readAsDataURL: jest.fn(),
+        onloadend: null as (() => void) | null,
+        result: mockDataUrl,
+      };
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      (global as any).FileReader = jest.fn(() => mockFileReader);
+
+      const { updateFavicon } = await import('../brandingLoader');
+
+      const updatePromise = updateFavicon(undefined);
+
+      // Wait for fetch to be called
+      await new Promise(resolve => setTimeout(resolve, 10));
+
+      // Trigger FileReader onloadend
+      if (mockFileReader.onloadend) {
+        mockFileReader.onloadend();
+      }
+
+      await updatePromise;
+
+      // Should have fetched favicon.ico
+      expect(mockFetch).toHaveBeenCalledWith('/dashboard/assets/branding/favicon.ico');
+
+      // Should cache the fetched favicon
+      expect(mockSessionStorage[BRANDING_FAVICON_KEY]).toBe(mockDataUrl);
+
+      // Should update favicon element
+      expect(mockFaviconElement.setAttribute).toHaveBeenCalledWith('href', mockDataUrl);
+    });
+
+    it('should not update favicon when fetch fails and dashboardFavicon is undefined', async () => {
+      mockFetch.mockResolvedValue({
+        ok: false,
+      });
+
+      const { updateFavicon } = await import('../brandingLoader');
+
+      await updateFavicon(undefined);
+
+      // Should have tried to fetch favicon.ico
+      expect(mockFetch).toHaveBeenCalledWith('/dashboard/assets/branding/favicon.ico');
+
+      // Should not cache or update anything
+      expect(mockSessionStorage[BRANDING_FAVICON_KEY]).toBeUndefined();
+      expect(mockFaviconElement.setAttribute).not.toHaveBeenCalled();
+    });
+  });
+});