diff --git a/demo/src/custom-cards/ha-demo-card.ts b/demo/src/custom-cards/ha-demo-card.ts
index 999aff5afc..2a464c2c1b 100644
--- a/demo/src/custom-cards/ha-demo-card.ts
+++ b/demo/src/custom-cards/ha-demo-card.ts
@@ -26,7 +26,7 @@ export class HADemoCard extends LitElement implements LovelaceCard {
 
   @state() private _switching = false;
 
-  private _hidden = localStorage.hide_demo_card;
+  private _hidden = window.localStorage.getItem("hide_demo_card");
 
   public getCardSize() {
     return this._hidden ? 0 : 2;
diff --git a/landing-page/src/ha-landing-page.ts b/landing-page/src/ha-landing-page.ts
index 338fdbeafb..af8fec7d19 100644
--- a/landing-page/src/ha-landing-page.ts
+++ b/landing-page/src/ha-landing-page.ts
@@ -122,7 +122,10 @@ class HaLandingPage extends LandingPageBaseElement {
     if (language !== this.language && language) {
       this.language = language;
       try {
-        localStorage.setItem("selectedLanguage", JSON.stringify(language));
+        window.localStorage.setItem(
+          "selectedLanguage",
+          JSON.stringify(language)
+        );
       } catch (err: any) {
         // Ignore
       }
diff --git a/package.json b/package.json
index d0d75bfd31..21e1cc5cef 100644
--- a/package.json
+++ b/package.json
@@ -213,6 +213,7 @@
     "gulp-rename": "2.0.0",
     "html-minifier-terser": "7.2.0",
     "husky": "9.1.7",
+    "jsdom": "25.0.1",
     "jszip": "3.10.1",
     "lint-staged": "15.2.10",
     "lit-analyzer": "2.0.3",
diff --git a/src/auth/ha-authorize.ts b/src/auth/ha-authorize.ts
index 6cfb67b696..ae2d3abcd4 100644
--- a/src/auth/ha-authorize.ts
+++ b/src/auth/ha-authorize.ts
@@ -327,7 +327,7 @@ export class HaAuthorize extends litLocalizeLiteMixin(LitElement) {
     this.language = language;
 
     try {
-      localStorage.setItem("selectedLanguage", JSON.stringify(language));
+      window.localStorage.setItem("selectedLanguage", JSON.stringify(language));
     } catch (err: any) {
       // Ignore
     }
diff --git a/src/common/auth/token_storage.ts b/src/common/auth/token_storage.ts
index 4bfe18981c..5bcd7a64f2 100644
--- a/src/common/auth/token_storage.ts
+++ b/src/common/auth/token_storage.ts
@@ -1,8 +1,6 @@
 import type { AuthData } from "home-assistant-js-websocket";
 import { extractSearchParam } from "../url/search-params";
 
-const storage = window.localStorage || {};
-
 declare global {
   interface Window {
     __tokenCache: {
@@ -38,9 +36,15 @@ export function saveTokens(tokens: AuthData | null) {
 
   if (tokenCache.writeEnabled) {
     try {
-      storage.hassTokens = JSON.stringify(tokens);
+      window.localStorage.setItem("hassTokens", JSON.stringify(tokens));
     } catch (err: any) {
       // write failed, ignore it. Happens if storage is full or private mode.
+      // eslint-disable-next-line no-console
+      console.warn(
+        "Failed to store tokens; Are you in private mode or is your storage full?"
+      );
+      // eslint-disable-next-line no-console
+      console.error("Error storing tokens:", err);
     }
   }
 }
@@ -51,12 +55,11 @@ export function enableWrite() {
     saveTokens(tokenCache.tokens);
   }
 }
+
 export function loadTokens() {
   if (tokenCache.tokens === undefined) {
     try {
-      // Delete the old token cache.
-      delete storage.tokens;
-      const tokens = storage.hassTokens;
+      const tokens = window.localStorage.getItem("hassTokens");
       if (tokens) {
         tokenCache.tokens = JSON.parse(tokens);
         tokenCache.writeEnabled = true;
diff --git a/src/data/panel.ts b/src/data/panel.ts
index e6470e315e..14012b1059 100644
--- a/src/data/panel.ts
+++ b/src/data/panel.ts
@@ -4,10 +4,11 @@ import type { HomeAssistant, PanelInfo } from "../types";
 /** Panel to show when no panel is picked. */
 export const DEFAULT_PANEL = "lovelace";
 
-export const getStorageDefaultPanelUrlPath = (): string =>
-  localStorage.defaultPanel
-    ? JSON.parse(localStorage.defaultPanel)
-    : DEFAULT_PANEL;
+export const getStorageDefaultPanelUrlPath = (): string => {
+  const defaultPanel = window.localStorage.getItem("defaultPanel");
+
+  return defaultPanel ? JSON.parse(defaultPanel) : DEFAULT_PANEL;
+};
 
 export const setDefaultPanel = (
   element: HTMLElement,
diff --git a/src/onboarding/ha-onboarding.ts b/src/onboarding/ha-onboarding.ts
index 4716165ebe..5c82e575d8 100644
--- a/src/onboarding/ha-onboarding.ts
+++ b/src/onboarding/ha-onboarding.ts
@@ -482,7 +482,10 @@ class HaOnboarding extends litLocalizeLiteMixin(HassElement) {
       storeState(this.hass!);
     } else {
       try {
-        localStorage.setItem("selectedLanguage", JSON.stringify(language));
+        window.localStorage.setItem(
+          "selectedLanguage",
+          JSON.stringify(language)
+        );
       } catch (err: any) {
         // Ignore
       }
diff --git a/src/panels/config/automation/ha-automation-trace.ts b/src/panels/config/automation/ha-automation-trace.ts
index 536cdbbf45..1a21545e43 100644
--- a/src/panels/config/automation/ha-automation-trace.ts
+++ b/src/panels/config/automation/ha-automation-trace.ts
@@ -481,13 +481,14 @@ export class HaAutomationTrace extends LitElement {
     if (!traceText) {
       return;
     }
-    localStorage.devTrace = traceText;
+    window.localStorage.setItem("devTrace", traceText);
     this._loadLocalTrace(traceText);
   }
 
   private _loadLocalStorageTrace() {
-    if (localStorage.devTrace) {
-      this._loadLocalTrace(localStorage.devTrace);
+    const devTrace = window.localStorage.getItem("devTrace");
+    if (devTrace) {
+      this._loadLocalTrace(devTrace);
     }
   }
 
diff --git a/src/panels/config/script/ha-script-trace.ts b/src/panels/config/script/ha-script-trace.ts
index 1551c0fe3c..08b0561312 100644
--- a/src/panels/config/script/ha-script-trace.ts
+++ b/src/panels/config/script/ha-script-trace.ts
@@ -487,13 +487,15 @@ export class HaScriptTrace extends LitElement {
     if (!traceText) {
       return;
     }
-    localStorage.devTrace = traceText;
+
+    window.localStorage.setItem("devTrace", traceText);
     this._loadLocalTrace(traceText);
   }
 
   private _loadLocalStorageTrace() {
-    if (localStorage.devTrace) {
-      this._loadLocalTrace(localStorage.devTrace);
+    const devTrace = window.localStorage.getItem("devTrace");
+    if (devTrace) {
+      this._loadLocalTrace(devTrace);
     }
   }
 
diff --git a/src/util/ha-pref-storage.ts b/src/util/ha-pref-storage.ts
index 2f38739217..4ef259ff0c 100644
--- a/src/util/ha-pref-storage.ts
+++ b/src/util/ha-pref-storage.ts
@@ -10,16 +10,24 @@ const STORED_STATE = [
   "enableShortcuts",
   "defaultPanel",
 ];
-const STORAGE = window.localStorage || {};
 
 export function storeState(hass: HomeAssistant) {
   try {
     STORED_STATE.forEach((key) => {
       const value = hass[key];
-      STORAGE[key] = JSON.stringify(value === undefined ? null : value);
+      window.localStorage.setItem(
+        key,
+        JSON.stringify(value === undefined ? null : value)
+      );
     });
   } catch (err: any) {
     // Safari throws exception in private mode
+    // eslint-disable-next-line no-console
+    console.warn(
+      "Cannot store state; Are you in private mode or is your storage full?"
+    );
+    // eslint-disable-next-line no-console
+    console.error(err);
   }
 }
 
@@ -27,8 +35,9 @@ export function getState() {
   const state = {};
 
   STORED_STATE.forEach((key) => {
-    if (key in STORAGE) {
-      let value = JSON.parse(STORAGE[key]);
+    const storageItem = window.localStorage.getItem(key);
+    if (storageItem !== null) {
+      let value = JSON.parse(storageItem);
       // selectedTheme went from string to object on 20200718
       if (key === "selectedTheme" && typeof value === "string") {
         value = { theme: value };
@@ -44,8 +53,5 @@ export function getState() {
 }
 
 export function clearState() {
-  // STORAGE is an object if localStorage not available.
-  if (STORAGE.clear) {
-    STORAGE.clear();
-  }
+  window.localStorage.clear();
 }
diff --git a/test/common/auth/token_storage/askWrite.test.ts b/test/common/auth/token_storage/askWrite.test.ts
new file mode 100644
index 0000000000..2357d23edd
--- /dev/null
+++ b/test/common/auth/token_storage/askWrite.test.ts
@@ -0,0 +1,62 @@
+import { afterEach, describe, expect, test, vi } from "vitest";
+
+let askWrite;
+
+describe("token_storage.askWrite", () => {
+  afterEach(() => {
+    vi.resetModules();
+  });
+
+  test("askWrite", async () => {
+    vi.stubGlobal(
+      "window.__tokenCache",
+      (window.__tokenCache = {
+        tokens: undefined,
+        writeEnabled: true,
+      })
+    );
+
+    ({ askWrite } = await import("../../../../src/common/auth/token_storage"));
+    expect(askWrite()).toBe(false);
+  });
+
+  test("askWrite prefilled token", async () => {
+    vi.stubGlobal(
+      "window.__tokenCache",
+      (window.__tokenCache = {
+        tokens: {
+          access_token: "test",
+          expires: 1800,
+          expires_in: 1800,
+          hassUrl: "http://localhost",
+          refresh_token: "refresh",
+          clientId: "client",
+        },
+        writeEnabled: undefined,
+      })
+    );
+
+    ({ askWrite } = await import("../../../../src/common/auth/token_storage"));
+    expect(askWrite()).toBe(true);
+  });
+
+  test("askWrite prefilled token, write enabled", async () => {
+    vi.stubGlobal(
+      "window.__tokenCache",
+      (window.__tokenCache = {
+        tokens: {
+          access_token: "test",
+          expires: 1800,
+          expires_in: 1800,
+          hassUrl: "http://localhost",
+          refresh_token: "refresh",
+          clientId: "client",
+        },
+        writeEnabled: true,
+      })
+    );
+
+    ({ askWrite } = await import("../../../../src/common/auth/token_storage"));
+    expect(askWrite()).toBe(false);
+  });
+});
diff --git a/test/common/auth/token_storage/saveTokens.test.ts b/test/common/auth/token_storage/saveTokens.test.ts
new file mode 100644
index 0000000000..b98d310cf3
--- /dev/null
+++ b/test/common/auth/token_storage/saveTokens.test.ts
@@ -0,0 +1,140 @@
+import { afterEach, beforeEach, describe, expect, test, vi } from "vitest";
+import type { AuthData } from "home-assistant-js-websocket";
+import { FallbackStorage } from "../../../test_helper/local-storage-fallback";
+
+let saveTokens;
+
+describe("token_storage.saveTokens", () => {
+  beforeEach(() => {
+    window.localStorage = new FallbackStorage();
+  });
+
+  afterEach(() => {
+    vi.resetModules();
+    vi.resetAllMocks();
+  });
+
+  test("saveTokens", async () => {
+    const tokens: AuthData = {
+      access_token: "test",
+      expires: 1800,
+      expires_in: 1800,
+      hassUrl: "http://localhost",
+      refresh_token: "refresh",
+      clientId: "client",
+    };
+
+    vi.stubGlobal(
+      "window.__tokenCache",
+      (window.__tokenCache = {
+        tokens: undefined,
+        writeEnabled: undefined,
+      })
+    );
+
+    ({ saveTokens } = await import(
+      "../../../../src/common/auth/token_storage"
+    ));
+    saveTokens(tokens);
+    expect(window.__tokenCache.tokens).toEqual(tokens);
+  });
+
+  test("saveTokens write enabled", async () => {
+    const tokens: AuthData = {
+      access_token: "test",
+      expires: 1800,
+      expires_in: 1800,
+      hassUrl: "http://localhost",
+      refresh_token: "refresh",
+      clientId: "client",
+    };
+
+    vi.stubGlobal(
+      "window.__tokenCache",
+      (window.__tokenCache = {
+        tokens: undefined,
+        writeEnabled: undefined,
+      })
+    );
+
+    const extractSearchParamSpy = vi.fn().mockReturnValue("true");
+
+    vi.doMock("../../../../src/common/url/search-params", () => ({
+      extractSearchParam: extractSearchParamSpy,
+    }));
+    const setItemSpy = vi.fn();
+    window.localStorage.setItem = setItemSpy;
+
+    ({ saveTokens } = await import(
+      "../../../../src/common/auth/token_storage"
+    ));
+    saveTokens(tokens);
+    expect(window.__tokenCache.tokens).toEqual(tokens);
+    expect(window.__tokenCache.writeEnabled).toBe(true);
+    expect(extractSearchParamSpy).toHaveBeenCalledOnce();
+    expect(extractSearchParamSpy).toHaveBeenCalledWith("storeToken");
+    expect(setItemSpy).toHaveBeenCalledOnce();
+    expect(setItemSpy).toHaveBeenCalledWith(
+      "hassTokens",
+      JSON.stringify(tokens)
+    );
+  });
+
+  test("saveTokens write enabled full storage", async () => {
+    const tokens: AuthData = {
+      access_token: "test",
+      expires: 1800,
+      expires_in: 1800,
+      hassUrl: "http://localhost",
+      refresh_token: "refresh",
+      clientId: "client",
+    };
+
+    vi.stubGlobal(
+      "window.__tokenCache",
+      (window.__tokenCache = {
+        tokens: undefined,
+        writeEnabled: true,
+      })
+    );
+
+    const extractSearchParamSpy = vi.fn();
+
+    vi.doMock("../../../../src/common/url/search-params", () => ({
+      extractSearchParam: extractSearchParamSpy,
+    }));
+
+    const setItemSpy = vi.fn(() => {
+      throw new Error("Full storage");
+    });
+
+    window.localStorage.setItem = setItemSpy;
+
+    // eslint-disable-next-line no-global-assign
+    console = {
+      warn: vi.fn(),
+      error: vi.fn(),
+    } as unknown as Console;
+
+    ({ saveTokens } = await import(
+      "../../../../src/common/auth/token_storage"
+    ));
+    saveTokens(tokens);
+    expect(window.__tokenCache.tokens).toEqual(tokens);
+    expect(window.__tokenCache.writeEnabled).toBe(true);
+    expect(extractSearchParamSpy).toBeCalledTimes(0);
+    expect(setItemSpy).toHaveBeenCalledOnce();
+    expect(setItemSpy).toHaveBeenCalledWith(
+      "hassTokens",
+      JSON.stringify(tokens)
+    );
+    // eslint-disable-next-line no-console
+    expect(console.warn).toHaveBeenCalledOnce();
+    // eslint-disable-next-line no-console
+    expect(console.warn).toHaveBeenCalledWith(
+      "Failed to store tokens; Are you in private mode or is your storage full?"
+    );
+    // eslint-disable-next-line no-console
+    expect(console.error).toHaveBeenCalledOnce();
+  });
+});
diff --git a/test/common/auth/token_storage/token_storage.test.ts b/test/common/auth/token_storage/token_storage.test.ts
new file mode 100644
index 0000000000..42ed3ead23
--- /dev/null
+++ b/test/common/auth/token_storage/token_storage.test.ts
@@ -0,0 +1,110 @@
+import { describe, it, expect, test, vi, afterEach, beforeEach } from "vitest";
+import type { AuthData } from "home-assistant-js-websocket";
+import { FallbackStorage } from "../../../test_helper/local-storage-fallback";
+
+describe("token_storage", () => {
+  beforeEach(() => {
+    vi.stubGlobal(
+      "window.__tokenCache",
+      (window.__tokenCache = {
+        tokens: undefined,
+        writeEnabled: undefined,
+      })
+    );
+    window.localStorage = new FallbackStorage();
+  });
+
+  afterEach(() => {
+    vi.resetAllMocks();
+    vi.resetModules();
+  });
+
+  test("initialize tokenCache", async () => {
+    vi.stubGlobal(
+      "window.__tokenCache",
+      (window.__tokenCache = undefined as any)
+    );
+
+    await import("../../../../src/common/auth/token_storage");
+
+    expect(window.__tokenCache).toEqual({
+      tokens: undefined,
+      writeEnabled: undefined,
+    });
+  });
+
+  test("should load tokens", async () => {
+    const tokens: AuthData = {
+      access_token: "test",
+      expires: 1800,
+      expires_in: 1800,
+      hassUrl: "http://localhost",
+      refresh_token: "refresh",
+      clientId: "client",
+    };
+
+    const getItemSpy = vi.fn(() => JSON.stringify(tokens));
+    window.localStorage.getItem = getItemSpy;
+
+    const { loadTokens } = await import(
+      "../../../../src/common/auth/token_storage"
+    );
+
+    const loadedTokens = loadTokens();
+    expect(loadedTokens).toEqual(tokens);
+
+    expect(window.__tokenCache.tokens).toEqual(tokens);
+    expect(window.__tokenCache.writeEnabled).toBe(true);
+    expect(getItemSpy).toHaveBeenCalledOnce();
+    expect(getItemSpy).toHaveBeenCalledWith("hassTokens");
+  });
+
+  test("should load null tokens", async () => {
+    const getItemSpy = vi.fn(() => "hello");
+    window.localStorage.getItem = getItemSpy;
+
+    const { loadTokens } = await import(
+      "../../../../src/common/auth/token_storage"
+    );
+
+    const loadedTokens = loadTokens();
+    expect(loadedTokens).toEqual(null);
+
+    expect(window.__tokenCache.tokens).toEqual(null);
+    expect(window.__tokenCache.writeEnabled).toBe(undefined);
+    expect(getItemSpy).toHaveBeenCalledOnce();
+    expect(getItemSpy).toHaveBeenCalledWith("hassTokens");
+  });
+
+  it("should enable write", async () => {
+    const { enableWrite } = await import(
+      "../../../../src/common/auth/token_storage"
+    );
+    enableWrite();
+    expect(window.__tokenCache.writeEnabled).toBe(true);
+  });
+
+  it("should enable write with tokens", async () => {
+    vi.stubGlobal(
+      "window.__tokenCache",
+      (window.__tokenCache = {
+        tokens: "testToken" as any,
+      })
+    );
+
+    const setItemSpy = vi.fn();
+    window.localStorage.setItem = setItemSpy;
+
+    const { enableWrite } = await import(
+      "../../../../src/common/auth/token_storage"
+    );
+
+    enableWrite();
+    expect(window.__tokenCache.writeEnabled).toBe(true);
+    expect(setItemSpy).toHaveBeenCalledOnce();
+    expect(setItemSpy).toHaveBeenCalledWith(
+      "hassTokens",
+      JSON.stringify("testToken")
+    );
+  });
+});
diff --git a/test/test_helper/local-storage-fallback.test.ts b/test/test_helper/local-storage-fallback.test.ts
new file mode 100644
index 0000000000..67215444fe
--- /dev/null
+++ b/test/test_helper/local-storage-fallback.test.ts
@@ -0,0 +1,52 @@
+import { describe, test, expect, beforeEach } from "vitest";
+import { FallbackStorage } from "./local-storage-fallback";
+
+describe("FallbackStorage", () => {
+  let storage;
+
+  beforeEach(() => {
+    storage = new FallbackStorage();
+  });
+
+  test("should set and get an item", () => {
+    storage.setItem("key1", "value1");
+    expect(storage.getItem("key1")).toBe("value1");
+  });
+
+  test("should return null for non-existing item", () => {
+    expect(storage.getItem("nonExistingKey")).toBeNull();
+  });
+
+  test("should remove an item", () => {
+    storage.setItem("key2", "value2");
+    storage.removeItem("key2");
+    expect(storage.getItem("key2")).toBeNull();
+  });
+
+  test("should clear all items", () => {
+    storage.setItem("key3", "value3");
+    storage.setItem("key4", "value4");
+    storage.clear();
+    expect(storage.getItem("key3")).toBeNull();
+    expect(storage.getItem("key4")).toBeNull();
+  });
+
+  test("should return the correct key for an index", () => {
+    storage.setItem("key5", "value5");
+    storage.setItem("key6", "value6");
+    expect(storage.key(0)).toBe("key5");
+    expect(storage.key(1)).toBe("key6");
+  });
+
+  test("should throw TypeError if key method is called without arguments", () => {
+    expect(() => storage.key()).toThrow(TypeError);
+  });
+
+  test("should return the correct length", () => {
+    storage.setItem("key7", "value7");
+    storage.setItem("key8", "value8");
+    expect(storage.length).toBe(2);
+    storage.removeItem("key7");
+    expect(storage.length).toBe(1);
+  });
+});
diff --git a/test/test_helper/local-storage-fallback.ts b/test/test_helper/local-storage-fallback.ts
new file mode 100644
index 0000000000..b598902806
--- /dev/null
+++ b/test/test_helper/local-storage-fallback.ts
@@ -0,0 +1,38 @@
+export class FallbackStorage implements Storage {
+  private valuesMap = new Map();
+
+  getItem(key) {
+    const stringKey = String(key);
+    if (this.valuesMap.has(key)) {
+      return String(this.valuesMap.get(stringKey));
+    }
+    return null;
+  }
+
+  setItem(key, val) {
+    this.valuesMap.set(String(key), String(val));
+  }
+
+  removeItem(key) {
+    this.valuesMap.delete(key);
+  }
+
+  clear() {
+    this.valuesMap.clear();
+  }
+
+  key(i) {
+    if (arguments.length === 0) {
+      // this is a TypeError implemented on Chrome, Firefox throws Not enough arguments to Storage.key.
+      throw new TypeError(
+        "Failed to execute 'key' on 'Storage': 1 argument required, but only 0 present."
+      );
+    }
+    const arr = Array.from(this.valuesMap.keys());
+    return arr[i];
+  }
+
+  get length() {
+    return this.valuesMap.size;
+  }
+}
diff --git a/test/util/ha-pref-storage.test.ts b/test/util/ha-pref-storage.test.ts
new file mode 100644
index 0000000000..c984b7112b
--- /dev/null
+++ b/test/util/ha-pref-storage.test.ts
@@ -0,0 +1,113 @@
+import { describe, expect, afterEach, vi, test, beforeEach } from "vitest";
+import type { HomeAssistant } from "../../src/types";
+import { FallbackStorage } from "../test_helper/local-storage-fallback";
+
+describe("ha-pref-storage", () => {
+  const mockHass = {
+    dockedSidebar: "auto",
+    selectedTheme: { theme: "default" },
+    unknownKey: "unknownValue",
+  };
+
+  beforeEach(() => {
+    window.localStorage = new FallbackStorage();
+  });
+
+  afterEach(() => {
+    vi.resetModules();
+    vi.resetAllMocks();
+  });
+
+  test("storeState", async () => {
+    const { storeState } = await import("../../src/util/ha-pref-storage");
+
+    window.localStorage.setItem = vi.fn();
+
+    storeState(mockHass as unknown as HomeAssistant);
+    expect(window.localStorage.setItem).toHaveBeenCalledTimes(8);
+    expect(window.localStorage.setItem).toHaveBeenCalledWith(
+      "dockedSidebar",
+      JSON.stringify("auto")
+    );
+    expect(window.localStorage.setItem).toHaveBeenCalledWith(
+      "selectedTheme",
+      JSON.stringify({ theme: "default" })
+    );
+    expect(window.localStorage.setItem).toHaveBeenCalledWith(
+      "selectedLanguage",
+      JSON.stringify(null)
+    );
+    expect(window.localStorage.setItem).not.toHaveBeenCalledWith(
+      "unknownKey",
+      JSON.stringify("unknownValue")
+    );
+  });
+
+  test("storeState fails", async () => {
+    const { storeState } = await import("../../src/util/ha-pref-storage");
+
+    window.localStorage.setItem = vi.fn((key) => {
+      if (key === "selectedTheme") {
+        throw new Error("Test error");
+      }
+    });
+
+    // eslint-disable-next-line no-global-assign
+    console = {
+      warn: vi.fn(),
+      error: vi.fn(),
+    } as unknown as Console;
+
+    storeState(mockHass as unknown as HomeAssistant);
+    expect(window.localStorage.setItem).toHaveBeenCalledTimes(2);
+    expect(window.localStorage.setItem).toHaveBeenCalledWith(
+      "dockedSidebar",
+      JSON.stringify("auto")
+    );
+    expect(window.localStorage.setItem).toHaveBeenCalledWith(
+      "selectedTheme",
+      JSON.stringify({ theme: "default" })
+    );
+    expect(window.localStorage.setItem).not.toHaveBeenCalledWith(
+      "selectedLanguage",
+      JSON.stringify(null)
+    );
+    // eslint-disable-next-line no-console
+    expect(console.warn).toHaveBeenCalledOnce();
+    // eslint-disable-next-line no-console
+    expect(console.warn).toHaveBeenCalledWith(
+      "Cannot store state; Are you in private mode or is your storage full?"
+    );
+    // eslint-disable-next-line no-console
+    expect(console.error).toHaveBeenCalledOnce();
+  });
+
+  test("getState", async () => {
+    const { getState } = await import("../../src/util/ha-pref-storage");
+
+    window.localStorage.setItem("selectedTheme", JSON.stringify("test"));
+    window.localStorage.setItem("dockedSidebar", JSON.stringify(true));
+    window.localStorage.setItem("selectedLanguage", JSON.stringify("german"));
+
+    // should not be in state
+    window.localStorage.setItem("testEntry", JSON.stringify("this is a test"));
+
+    const state = getState();
+    expect(state).toEqual({
+      dockedSidebar: "docked",
+      selectedTheme: { theme: "test" },
+      selectedLanguage: "german",
+    });
+  });
+
+  test("clearState", async () => {
+    const { clearState } = await import("../../src/util/ha-pref-storage");
+
+    window.localStorage.setItem("test", "test");
+
+    expect(window.localStorage.length).toEqual(1);
+
+    clearState();
+    expect(window.localStorage.length).toEqual(0);
+  });
+});
diff --git a/test/vitest.config.ts b/test/vitest.config.ts
index ad284c6805..811a8a8a7d 100644
--- a/test/vitest.config.ts
+++ b/test/vitest.config.ts
@@ -2,13 +2,21 @@ import { defineConfig } from "vitest/config";
 
 export default defineConfig({
   test: {
+    environment: "jsdom", // to run in browser-like environment
     env: {
       TZ: "Etc/UTC",
       IS_TEST: "true",
     },
     setupFiles: ["./test/setup.ts"],
     coverage: {
-      include: ["src/data/**/*", "src/common/**/*"],
+      include: [
+        "src/data/**/*",
+        "src/common/**/*",
+        "src/external_app/**/*",
+        "src/hassio/**/*",
+        "src/panels/**/*",
+        "src/util/**/*",
+      ],
       reporter: ["text", "html"],
       provider: "v8",
       reportsDirectory: "test/coverage",
diff --git a/yarn.lock b/yarn.lock
index 46301df641..3de7c2b5b5 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -6888,6 +6888,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"cssstyle@npm:^4.1.0":
+  version: 4.1.0
+  resolution: "cssstyle@npm:4.1.0"
+  dependencies:
+    rrweb-cssom: "npm:^0.7.1"
+  checksum: 10/8ca9e2d1f1b24f93bb5f3f20a7a1e271e58060957880e985ee55614e196a798ffab309ec6bac105af8a439a6764546761813835ebb7f929d60823637ee838a8f
+  languageName: node
+  linkType: hard
+
 "csstype@npm:^3.1.0":
   version: 3.1.3
   resolution: "csstype@npm:3.1.3"
@@ -6895,6 +6904,16 @@ __metadata:
   languageName: node
   linkType: hard
 
+"data-urls@npm:^5.0.0":
+  version: 5.0.0
+  resolution: "data-urls@npm:5.0.0"
+  dependencies:
+    whatwg-mimetype: "npm:^4.0.0"
+    whatwg-url: "npm:^14.0.0"
+  checksum: 10/5c40568c31b02641a70204ff233bc4e42d33717485d074244a98661e5f2a1e80e38fe05a5755dfaf2ee549f2ab509d6a3af2a85f4b2ad2c984e5d176695eaf46
+  languageName: node
+  linkType: hard
+
 "data-view-buffer@npm:^1.0.1":
   version: 1.0.1
   resolution: "data-view-buffer@npm:1.0.1"
@@ -6995,6 +7014,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"decimal.js@npm:^10.4.3":
+  version: 10.4.3
+  resolution: "decimal.js@npm:10.4.3"
+  checksum: 10/de663a7bc4d368e3877db95fcd5c87b965569b58d16cdc4258c063d231ca7118748738df17cd638f7e9dd0be8e34cec08d7234b20f1f2a756a52fc5a38b188d0
+  languageName: node
+  linkType: hard
+
 "deep-clone-simple@npm:1.1.1":
   version: 1.1.1
   resolution: "deep-clone-simple@npm:1.1.1"
@@ -9240,6 +9266,7 @@ __metadata:
     idb-keyval: "npm:6.2.1"
     intl-messageformat: "npm:10.7.7"
     js-yaml: "npm:4.1.0"
+    jsdom: "npm:25.0.1"
     jszip: "npm:3.10.1"
     leaflet: "npm:1.9.4"
     leaflet-draw: "patch:leaflet-draw@npm%3A1.0.4#./.yarn/patches/leaflet-draw-npm-1.0.4-0ca0ebcf65.patch"
@@ -9328,6 +9355,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"html-encoding-sniffer@npm:^4.0.0":
+  version: 4.0.0
+  resolution: "html-encoding-sniffer@npm:4.0.0"
+  dependencies:
+    whatwg-encoding: "npm:^3.1.1"
+  checksum: 10/e86efd493293a5671b8239bd099d42128433bb3c7b0fdc7819282ef8e118a21f5dead0ad6f358e024a4e5c84f17ebb7a9b36075220fac0a6222b207248bede6f
+  languageName: node
+  linkType: hard
+
 "html-entities@npm:^2.4.0":
   version: 2.5.2
   resolution: "html-entities@npm:2.5.2"
@@ -9422,7 +9458,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"http-proxy-agent@npm:^7.0.0":
+"http-proxy-agent@npm:^7.0.0, http-proxy-agent@npm:^7.0.2":
   version: 7.0.2
   resolution: "http-proxy-agent@npm:7.0.2"
   dependencies:
@@ -9461,7 +9497,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"https-proxy-agent@npm:^7.0.1":
+"https-proxy-agent@npm:^7.0.1, https-proxy-agent@npm:^7.0.5":
   version: 7.0.5
   resolution: "https-proxy-agent@npm:7.0.5"
   dependencies:
@@ -9510,7 +9546,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"iconv-lite@npm:^0.6.2, iconv-lite@npm:^0.6.3":
+"iconv-lite@npm:0.6.3, iconv-lite@npm:^0.6.2, iconv-lite@npm:^0.6.3":
   version: 0.6.3
   resolution: "iconv-lite@npm:0.6.3"
   dependencies:
@@ -9949,7 +9985,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"is-potential-custom-element-name@npm:^1.0.0":
+"is-potential-custom-element-name@npm:^1.0.0, is-potential-custom-element-name@npm:^1.0.1":
   version: 1.0.1
   resolution: "is-potential-custom-element-name@npm:1.0.1"
   checksum: 10/ced7bbbb6433a5b684af581872afe0e1767e2d1146b2207ca0068a648fb5cab9d898495d1ac0583524faaf24ca98176a7d9876363097c2d14fee6dd324f3a1ab
@@ -10255,6 +10291,40 @@ __metadata:
   languageName: node
   linkType: hard
 
+"jsdom@npm:25.0.1":
+  version: 25.0.1
+  resolution: "jsdom@npm:25.0.1"
+  dependencies:
+    cssstyle: "npm:^4.1.0"
+    data-urls: "npm:^5.0.0"
+    decimal.js: "npm:^10.4.3"
+    form-data: "npm:^4.0.0"
+    html-encoding-sniffer: "npm:^4.0.0"
+    http-proxy-agent: "npm:^7.0.2"
+    https-proxy-agent: "npm:^7.0.5"
+    is-potential-custom-element-name: "npm:^1.0.1"
+    nwsapi: "npm:^2.2.12"
+    parse5: "npm:^7.1.2"
+    rrweb-cssom: "npm:^0.7.1"
+    saxes: "npm:^6.0.0"
+    symbol-tree: "npm:^3.2.4"
+    tough-cookie: "npm:^5.0.0"
+    w3c-xmlserializer: "npm:^5.0.0"
+    webidl-conversions: "npm:^7.0.0"
+    whatwg-encoding: "npm:^3.1.1"
+    whatwg-mimetype: "npm:^4.0.0"
+    whatwg-url: "npm:^14.0.0"
+    ws: "npm:^8.18.0"
+    xml-name-validator: "npm:^5.0.0"
+  peerDependencies:
+    canvas: ^2.11.2
+  peerDependenciesMeta:
+    canvas:
+      optional: true
+  checksum: 10/e6bf7250ddd2fbcf68da0ea041a0dc63545dc4bf77fa3ff40a46ae45b1dac1ca55b87574ab904d1f8baeeb547c52cec493a22f545d7d413b320011f41150ec49
+  languageName: node
+  linkType: hard
+
 "jsesc@npm:^3.0.2, jsesc@npm:~3.0.2":
   version: 3.0.2
   resolution: "jsesc@npm:3.0.2"
@@ -11389,6 +11459,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"nwsapi@npm:^2.2.12":
+  version: 2.2.16
+  resolution: "nwsapi@npm:2.2.16"
+  checksum: 10/1e5e086cdd4ca4a45f414d37f49bf0ca81d84ed31c6871ac68f531917d2910845db61f77c6d844430dc90fda202d43fce9603024e74038675de95229eb834dba
+  languageName: node
+  linkType: hard
+
 "object-assign@npm:^4":
   version: 4.1.1
   resolution: "object-assign@npm:4.1.1"
@@ -12220,7 +12297,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"punycode@npm:2.3.1, punycode@npm:^2.1.0":
+"punycode@npm:2.3.1, punycode@npm:^2.1.0, punycode@npm:^2.3.1":
   version: 2.3.1
   resolution: "punycode@npm:2.3.1"
   checksum: 10/febdc4362bead22f9e2608ff0171713230b57aff9dddc1c273aa2a651fbd366f94b7d6a71d78342a7c0819906750351ca7f2edd26ea41b626d87d6a13d1bd059
@@ -12673,8 +12750,8 @@ __metadata:
   linkType: hard
 
 "rollup@npm:^2.43.1":
-  version: 2.79.2
-  resolution: "rollup@npm:2.79.2"
+  version: 2.79.1
+  resolution: "rollup@npm:2.79.1"
   dependencies:
     fsevents: "npm:~2.3.2"
   dependenciesMeta:
@@ -12682,7 +12759,7 @@ __metadata:
       optional: true
   bin:
     rollup: dist/bin/rollup
-  checksum: 10/095ba0a82811b1866a76d826987743278db0a87c45092656986bfff490326b66187d5f9ff0c24cf8d5682bc470aa00c36654e0044d6b6335ac0c1201b8280880
+  checksum: 10/df087b701304432f30922bbee5f534ab189aa6938bd383b5686c03147e0d00cd1789ea10a462361326ce6b6ebe448ce272ad3f3cc40b82eeb3157df12f33663c
   languageName: node
   linkType: hard
 
@@ -12764,6 +12841,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"rrweb-cssom@npm:^0.7.1":
+  version: 0.7.1
+  resolution: "rrweb-cssom@npm:0.7.1"
+  checksum: 10/e80cf25c223a823921d7ab57c0ce78f5b7ebceab857b400cce99dd4913420ce679834bc5707e8ada47d062e21ad368108a9534c314dc8d72c20aa4a4fa0ed16a
+  languageName: node
+  linkType: hard
+
 "rslog@npm:^1.2.3":
   version: 1.2.3
   resolution: "rslog@npm:1.2.3"
@@ -12852,6 +12936,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"saxes@npm:^6.0.0":
+  version: 6.0.0
+  resolution: "saxes@npm:6.0.0"
+  dependencies:
+    xmlchars: "npm:^2.2.0"
+  checksum: 10/97b50daf6ca3a153e89842efa18a862e446248296622b7473c169c84c823ee8a16e4a43bac2f73f11fc8cb9168c73fbb0d73340f26552bac17970e9052367aa9
+  languageName: node
+  linkType: hard
+
 "schema-utils@npm:^3.1.1":
   version: 3.3.0
   resolution: "schema-utils@npm:3.3.0"
@@ -13721,6 +13814,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"symbol-tree@npm:^3.2.4":
+  version: 3.2.4
+  resolution: "symbol-tree@npm:3.2.4"
+  checksum: 10/c09a00aadf279d47d0c5c46ca3b6b2fbaeb45f0a184976d599637d412d3a70bbdc043ff33effe1206dea0e36e0ad226cb957112e7ce9a4bf2daedf7fa4f85c53
+  languageName: node
+  linkType: hard
+
 "systemjs@npm:6.15.1":
   version: 6.15.1
   resolution: "systemjs@npm:6.15.1"
@@ -13966,6 +14066,24 @@ __metadata:
   languageName: node
   linkType: hard
 
+"tldts-core@npm:^6.1.65":
+  version: 6.1.65
+  resolution: "tldts-core@npm:6.1.65"
+  checksum: 10/06ae49ae935674163d806aa14abf6bb49a6099878ef3940de035c6bf577cf31b78122df02d2e82d84d0a59faf8a837235d537ee7cbf9a5b0b97b44b7a5f19799
+  languageName: node
+  linkType: hard
+
+"tldts@npm:^6.1.32":
+  version: 6.1.65
+  resolution: "tldts@npm:6.1.65"
+  dependencies:
+    tldts-core: "npm:^6.1.65"
+  bin:
+    tldts: bin/cli.js
+  checksum: 10/dc8afe3ac8af4f2dc4b4307d447b6877ee5942e4b8164ae170edf034a318241ca7f9bdf89d4560204363141344959aa4d28edc532397b210532e160acbf77b6a
+  languageName: node
+  linkType: hard
+
 "to-regex-range@npm:^5.0.1":
   version: 5.0.1
   resolution: "to-regex-range@npm:5.0.1"
@@ -14015,6 +14133,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"tough-cookie@npm:^5.0.0":
+  version: 5.0.0
+  resolution: "tough-cookie@npm:5.0.0"
+  dependencies:
+    tldts: "npm:^6.1.32"
+  checksum: 10/a98d3846ed386e399e8b470c1eb08a6a296944246eabc55c9fe79d629bd2cdaa62f5a6572f271fe0060987906bd20468d72a219a3b4cbe51086bea48d2d677b6
+  languageName: node
+  linkType: hard
+
 "tr46@npm:^1.0.1":
   version: 1.0.1
   resolution: "tr46@npm:1.0.1"
@@ -14024,6 +14151,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"tr46@npm:^5.0.0":
+  version: 5.0.0
+  resolution: "tr46@npm:5.0.0"
+  dependencies:
+    punycode: "npm:^2.3.1"
+  checksum: 10/29155adb167d048d3c95d181f7cb5ac71948b4e8f3070ec455986e1f34634acae50ae02a3c8d448121c3afe35b76951cd46ed4c128fd80264280ca9502237a3e
+  languageName: node
+  linkType: hard
+
 "tree-dump@npm:^1.0.1":
   version: 1.0.2
   resolution: "tree-dump@npm:1.0.2"
@@ -14836,6 +14972,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"w3c-xmlserializer@npm:^5.0.0":
+  version: 5.0.0
+  resolution: "w3c-xmlserializer@npm:5.0.0"
+  dependencies:
+    xml-name-validator: "npm:^5.0.0"
+  checksum: 10/d78f59e6b4f924aa53b6dfc56949959229cae7fe05ea9374eb38d11edcec01398b7f5d7a12576bd5acc57ff446abb5c9115cd83b9d882555015437cf858d42f0
+  languageName: node
+  linkType: hard
+
 "wbuf@npm:^1.1.0, wbuf@npm:^1.7.3":
   version: 1.7.3
   resolution: "wbuf@npm:1.7.3"
@@ -14876,6 +15021,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"webidl-conversions@npm:^7.0.0":
+  version: 7.0.0
+  resolution: "webidl-conversions@npm:7.0.0"
+  checksum: 10/4c4f65472c010eddbe648c11b977d048dd96956a625f7f8b9d64e1b30c3c1f23ea1acfd654648426ce5c743c2108a5a757c0592f02902cf7367adb7d14e67721
+  languageName: node
+  linkType: hard
+
 "webpack-bundle-analyzer@npm:4.6.1":
   version: 4.6.1
   resolution: "webpack-bundle-analyzer@npm:4.6.1"
@@ -15035,6 +15187,32 @@ __metadata:
   languageName: node
   linkType: hard
 
+"whatwg-encoding@npm:^3.1.1":
+  version: 3.1.1
+  resolution: "whatwg-encoding@npm:3.1.1"
+  dependencies:
+    iconv-lite: "npm:0.6.3"
+  checksum: 10/bbef815eb67f91487c7f2ef96329743f5fd8357d7d62b1119237d25d41c7e452dff8197235b2d3c031365a17f61d3bb73ca49d0ed1582475aa4a670815e79534
+  languageName: node
+  linkType: hard
+
+"whatwg-mimetype@npm:^4.0.0":
+  version: 4.0.0
+  resolution: "whatwg-mimetype@npm:4.0.0"
+  checksum: 10/894a618e2d90bf444b6f309f3ceb6e58cf21b2beaa00c8b333696958c4076f0c7b30b9d33413c9ffff7c5832a0a0c8569e5bb347ef44beded72aeefd0acd62e8
+  languageName: node
+  linkType: hard
+
+"whatwg-url@npm:^14.0.0":
+  version: 14.1.0
+  resolution: "whatwg-url@npm:14.1.0"
+  dependencies:
+    tr46: "npm:^5.0.0"
+    webidl-conversions: "npm:^7.0.0"
+  checksum: 10/3afd325de6cf3a367820ce7c3566a1f78eb1409c4f27b1867c74c76dab096d26acedf49a8b9b71db53df7d806ec2e9ae9ed96990b2f7d1abe6ecf1fe753af6eb
+  languageName: node
+  linkType: hard
+
 "whatwg-url@npm:^7.0.0":
   version: 7.1.0
   resolution: "whatwg-url@npm:7.1.0"
@@ -15494,7 +15672,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"ws@npm:^8.16.0":
+"ws@npm:^8.16.0, ws@npm:^8.18.0":
   version: 8.18.0
   resolution: "ws@npm:8.18.0"
   peerDependencies:
@@ -15536,6 +15714,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"xml-name-validator@npm:^5.0.0":
+  version: 5.0.0
+  resolution: "xml-name-validator@npm:5.0.0"
+  checksum: 10/43f30f3f6786e406dd665acf08cd742d5f8a46486bd72517edb04b27d1bcd1599664c2a4a99fc3f1e56a3194bff588b12f178b7972bc45c8047bdc4c3ac8d4a1
+  languageName: node
+  linkType: hard
+
 "xml-parse-from-string@npm:^1.0.0":
   version: 1.0.1
   resolution: "xml-parse-from-string@npm:1.0.1"
@@ -15560,6 +15745,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"xmlchars@npm:^2.2.0":
+  version: 2.2.0
+  resolution: "xmlchars@npm:2.2.0"
+  checksum: 10/4ad5924974efd004a47cce6acf5c0269aee0e62f9a805a426db3337af7bcbd331099df174b024ace4fb18971b8a56de386d2e73a1c4b020e3abd63a4a9b917f1
+  languageName: node
+  linkType: hard
+
 "xss@npm:1.0.15":
   version: 1.0.15
   resolution: "xss@npm:1.0.15"