diff --git a/src/renderer/__helpers__/vitest.dom.setup.ts b/src/renderer/__helpers__/vitest.dom.setup.ts
new file mode 100644
index 000000000..32377700f
--- /dev/null
+++ b/src/renderer/__helpers__/vitest.dom.setup.ts
@@ -0,0 +1,55 @@
+/**
+ * Minimal DOM-globals setup for renderer .ts test files that run in the node project
+ * but opt into a DOM environment via `// @vitest-environment happy-dom`.
+ *
+ * This file is added to the node project's `setupFiles` so that it runs for
+ * every test in that project. The `typeof window !== 'undefined'` guard makes
+ * it a no-op for tests that stay in the real node environment, while tests
+ * that declare `// @vitest-environment happy-dom` at the top of their file
+ * get the full `window.gitify` context bridge mock they need.
+ */
+
+if (typeof window !== 'undefined') {
+  window.gitify = {
+    app: {
+      version: vi.fn().mockResolvedValue('v0.0.1'),
+      hide: vi.fn(),
+      quit: vi.fn(),
+      show: vi.fn(),
+    },
+    twemojiDirectory: vi.fn().mockResolvedValue('/mock/images/assets'),
+    openExternalLink: vi.fn(),
+    decryptValue: vi.fn().mockResolvedValue('decrypted'),
+    encryptValue: vi.fn().mockResolvedValue('encrypted'),
+    platform: {
+      isLinux: vi.fn().mockReturnValue(false),
+      isMacOS: vi.fn().mockReturnValue(true),
+      isWindows: vi.fn().mockReturnValue(false),
+    },
+    zoom: {
+      getLevel: vi.fn(),
+      setLevel: vi.fn(),
+    },
+    tray: {
+      updateColor: vi.fn(),
+      updateTitle: vi.fn(),
+      useAlternateIdleIcon: vi.fn(),
+      useUnreadActiveIcon: vi.fn(),
+    },
+    notificationSoundPath: vi.fn(),
+    onAuthCallback: vi.fn(),
+    onResetApp: vi.fn(),
+    onSystemThemeUpdate: vi.fn(),
+    setAutoLaunch: vi.fn(),
+    applyKeyboardShortcut: vi.fn().mockResolvedValue({ success: true }),
+    raiseNativeNotification: vi.fn(),
+  };
+
+  Object.defineProperty(navigator, 'clipboard', {
+    value: {
+      writeText: vi.fn().mockResolvedValue(undefined),
+      readText: vi.fn().mockResolvedValue(''),
+    },
+    configurable: true,
+  });
+}
diff --git a/src/renderer/hooks/useNotifications.test.ts b/src/renderer/hooks/useNotifications.test.ts
index d71df2328..15542d351 100644
--- a/src/renderer/hooks/useNotifications.test.ts
+++ b/src/renderer/hooks/useNotifications.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment happy-dom
 import { act, renderHook, waitFor } from '@testing-library/react';
 
 import {
diff --git a/src/renderer/stores/useFiltersStore.test.ts b/src/renderer/stores/useFiltersStore.test.ts
index 3d76f680c..ad7d3b36c 100644
--- a/src/renderer/stores/useFiltersStore.test.ts
+++ b/src/renderer/stores/useFiltersStore.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment happy-dom
 import { act, renderHook } from '@testing-library/react';
 
 import type { SearchToken } from '../types';
diff --git a/src/renderer/utils/api/octokit.test.ts b/src/renderer/utils/api/octokit.test.ts
index 2a394abb8..d375512c4 100644
--- a/src/renderer/utils/api/octokit.test.ts
+++ b/src/renderer/utils/api/octokit.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment happy-dom
 import {
   mockGitHubAppAccount,
   mockGitHubCloudAccount,
diff --git a/src/renderer/utils/auth/flows.test.ts b/src/renderer/utils/auth/flows.test.ts
index 73dacce24..ed9284544 100644
--- a/src/renderer/utils/auth/flows.test.ts
+++ b/src/renderer/utils/auth/flows.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment happy-dom
 // Use a hoist-safe mock factory for '@octokit/oauth-methods'
 vi.mock('@octokit/oauth-methods', async () => {
   const actual = await vi.importActual<typeof import('@octokit/oauth-methods')>(
diff --git a/src/renderer/utils/auth/utils.test.ts b/src/renderer/utils/auth/utils.test.ts
index 2cd041170..87d68ba76 100644
--- a/src/renderer/utils/auth/utils.test.ts
+++ b/src/renderer/utils/auth/utils.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment happy-dom
 import { mockGitHubCloudAccount } from '../../__mocks__/account-mocks';
 import { mockAuth } from '../../__mocks__/state-mocks';
 import { mockRawUser } from '../api/__mocks__/response-mocks';
diff --git a/src/renderer/utils/notifications/filters/filter.test.ts b/src/renderer/utils/notifications/filters/filter.test.ts
index 5b0b2c48f..dbdb23eca 100644
--- a/src/renderer/utils/notifications/filters/filter.test.ts
+++ b/src/renderer/utils/notifications/filters/filter.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment happy-dom
 import { mockPartialGitifyNotification } from '../../../__mocks__/notifications-mocks';
 import { mockSettings } from '../../../__mocks__/state-mocks';
 
@@ -8,6 +9,10 @@ import type { GitifyOwner, Link, SearchToken } from '../../../types';
 import { filterBaseNotifications, filterDetailedNotifications } from './filter';
 
 describe('renderer/utils/notifications/filters/filter.ts', () => {
+  beforeEach(() => {
+    useFiltersStore.getState().reset();
+  });
+
   describe('filterNotifications', () => {
     const mockNotifications = [
       mockPartialGitifyNotification(
diff --git a/src/renderer/utils/system/audio.test.ts b/src/renderer/utils/system/audio.test.ts
index d903105a8..359fa1b01 100644
--- a/src/renderer/utils/system/audio.test.ts
+++ b/src/renderer/utils/system/audio.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment happy-dom
 import type { Percentage } from '../../types';
 
 import { raiseSoundNotification } from './audio';
diff --git a/src/renderer/utils/system/comms.test.ts b/src/renderer/utils/system/comms.test.ts
index f3869d4e8..513f3737e 100644
--- a/src/renderer/utils/system/comms.test.ts
+++ b/src/renderer/utils/system/comms.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment happy-dom
 import { mockSettings } from '../../__mocks__/state-mocks';
 
 import { type Link, OpenPreference } from '../../types';
diff --git a/src/renderer/utils/system/keyboardShortcut.test.ts b/src/renderer/utils/system/keyboardShortcut.test.ts
index 2ea357e4e..7e8943e77 100644
--- a/src/renderer/utils/system/keyboardShortcut.test.ts
+++ b/src/renderer/utils/system/keyboardShortcut.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment happy-dom
 import {
   formatAcceleratorForDisplay,
   keyboardEventToAccelerator,
diff --git a/src/renderer/utils/system/native.test.ts b/src/renderer/utils/system/native.test.ts
index 5d5158af7..457675dad 100644
--- a/src/renderer/utils/system/native.test.ts
+++ b/src/renderer/utils/system/native.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment happy-dom
 import { waitFor } from '@testing-library/react';
 
 import {
diff --git a/src/renderer/utils/system/tray.test.ts b/src/renderer/utils/system/tray.test.ts
index 4d76bba35..886266e21 100644
--- a/src/renderer/utils/system/tray.test.ts
+++ b/src/renderer/utils/system/tray.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment happy-dom
 import { mockSettings } from '../../__mocks__/state-mocks';
 
 import type { SettingsState } from '../../types';
diff --git a/src/renderer/utils/ui/zoom.test.ts b/src/renderer/utils/ui/zoom.test.ts
index e602dc6c5..1749f8c05 100644
--- a/src/renderer/utils/ui/zoom.test.ts
+++ b/src/renderer/utils/ui/zoom.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment happy-dom
 import type { Percentage } from '../../types';
 
 import {
diff --git a/vitest.config.ts b/vitest.config.ts
index d099e8482..cebf7808d 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -37,21 +37,25 @@ export default defineConfig({
           css: true,
           include: [
             'src/preload/**/*.test.{ts,tsx}',
-            'src/renderer/**/*.test.{ts,tsx}',
+            'src/renderer/**/*.test.tsx',
           ],
           setupFiles: ['./src/renderer/__helpers__/vitest.setup.ts'],
         },
       },
       {
-        // TODO - Opportunity in future to move some of the renderer util tests to node environment
         extends: true,
         test: {
-          name: 'node [main, shared]',
+          name: 'node [main, shared, renderer utils]',
           environment: 'node',
           include: [
             'src/shared/**/*.test.{ts,tsx}',
             'src/main/**/*.test.{ts,tsx}',
+            'src/renderer/**/*.test.ts',
           ],
+          // Conditionally sets up window.gitify for .ts files that opt into
+          // happy-dom via the `// @vitest-environment happy-dom` file docblock.
+          // The guard in the setup file makes it a no-op for pure node tests.
+          setupFiles: ['./src/renderer/__helpers__/vitest.dom.setup.ts'],
         },
       },
     ],