diff --git a/ui/src/AppBoot.test.tsx b/ui/src/AppBoot.test.tsx
index 296feaddc..ce88957b8 100644
--- a/ui/src/AppBoot.test.tsx
+++ b/ui/src/AppBoot.test.tsx
@@ -20,18 +20,14 @@ const MockSettings = (defaultFilters: string[]) => {
     const filtersBase64 = btoa(JSON.stringify(defaultFilters));
     const settings = document.createElement("span");
     settings.id = "settings";
-    (settings as any).dataset = {
-      defaultFiltersBase64: filtersBase64,
-    };
+    settings.dataset.defaultFiltersBase64 = filtersBase64;
     return settings;
   });
 };
 
-const FiltersSetting = (filters: any) => {
+const FiltersSetting = (filters: unknown) => {
   const settings = document.createElement("span");
-  (settings as any).dataset = {
-    defaultFiltersBase64: btoa(JSON.stringify(filters)),
-  };
+  settings.dataset.defaultFiltersBase64 = btoa(JSON.stringify(filters));
   return ParseDefaultFilters(settings);
 };
 
@@ -45,20 +41,19 @@ describe("SettingsElement()", () => {
     const spy = MockSettings([]);
     const settings = SettingsElement();
     expect(spy).toHaveBeenCalledTimes(1);
-    expect((settings as any).id).toBe("settings");
+    expect(settings?.id).toBe("settings");
   });
 });
 
 describe("ParseDefaultFilters()", () => {
   it("returns [] on missing filters attr", () => {
     const settings = document.createElement("span");
-    (settings as any).dataset = {};
     expect(ParseDefaultFilters(settings)).toHaveLength(0);
   });
 
   it("returns [] on empty filters attr", () => {
     const settings = document.createElement("span");
-    (settings as any).dataset = { defaultFiltersBase64: "" };
+    settings.dataset.defaultFiltersBase64 = "";
     expect(ParseDefaultFilters(settings)).toHaveLength(0);
   });
 
@@ -82,9 +77,7 @@ describe("ParseDefaultFilters()", () => {
   it("ignores template placeholder values", () => {
     // Scenario: default filters attribute rendered with the literal template placeholder should be ignored
     const settings = document.createElement("span");
-    (settings as any).dataset = {
-      defaultFiltersBase64: "{{ .DefaultFilter }}",
-    };
+    settings.dataset.defaultFiltersBase64 = "{{ .DefaultFilter }}";
     expect(ParseDefaultFilters(settings)).toHaveLength(0);
   });
 });
diff --git a/ui/src/Components/AlertAck/index.test.tsx b/ui/src/Components/AlertAck/index.test.tsx
index 48db0086e..1508eb01f 100644
--- a/ui/src/Components/AlertAck/index.test.tsx
+++ b/ui/src/Components/AlertAck/index.test.tsx
@@ -310,7 +310,7 @@ describe("<AlertAck />", () => {
     silenceFormStore.data.setAuthor("karma/ui");
     await renderAndClick();
     expect(
-      JSON.parse((fetchMock.callHistory.lastCall()?.options as any).body),
+      JSON.parse(fetchMock.callHistory.lastCall()!.options.body as string),
     ).toEqual({
       comment: "COMMENT",
       createdBy: "karma/ui",
@@ -342,7 +342,7 @@ describe("<AlertAck />", () => {
     });
     await renderAndClick();
     expect(
-      JSON.parse((fetchMock.callHistory.lastCall()?.options as any).body),
+      JSON.parse(fetchMock.callHistory.lastCall()!.options.body as string),
     ).toEqual({
       comment: "comment",
       createdBy: "me",
@@ -374,7 +374,7 @@ describe("<AlertAck />", () => {
     });
     await renderAndClick();
     expect(
-      JSON.parse((fetchMock.callHistory.lastCall()?.options as any).body),
+      JSON.parse(fetchMock.callHistory.lastCall()!.options.body as string),
     ).toEqual({
       comment:
         "ACK! This alert was acknowledged using karma on Tue, 01 Feb 2000 00:00:00 GMT",
@@ -407,7 +407,7 @@ describe("<AlertAck />", () => {
     });
     await renderAndClick();
     const comment = JSON.parse(
-      (fetchMock.callHistory.lastCall()?.options as any).body,
+      fetchMock.callHistory.lastCall()!.options.body as string,
     ).comment;
     expect(comment).not.toEqual(
       "ACK! This alert was acknowledged using karma on Tue Feb 01 2000 00:00:00 GMT",
@@ -432,7 +432,7 @@ describe("<AlertAck />", () => {
     });
     await renderAndClick();
     expect(
-      JSON.parse((fetchMock.callHistory.lastCall()?.options as any).body),
+      JSON.parse(fetchMock.callHistory.lastCall()!.options.body as string),
     ).toEqual({
       comment: "FOO: bar",
       createdBy: "auth@example.com",
@@ -466,7 +466,7 @@ describe("<AlertAck />", () => {
     silenceFormStore.data.setAuthor("bob@example.com");
     await renderAndClick();
     expect(
-      JSON.parse((fetchMock.callHistory.lastCall()?.options as any).body),
+      JSON.parse(fetchMock.callHistory.lastCall()!.options.body as string),
     ).toEqual({
       comment: "FOO: bar",
       createdBy: "bob@example.com",
@@ -499,7 +499,7 @@ describe("<AlertAck />", () => {
     silenceFormStore.data.setAuthor("");
     await renderAndClick();
     expect(
-      JSON.parse((fetchMock.callHistory.lastCall()?.options as any).body),
+      JSON.parse(fetchMock.callHistory.lastCall()!.options.body as string),
     ).toEqual({
       comment: "FOO: bar",
       createdBy: "me",
diff --git a/ui/src/Components/AlertHistory/index.test.tsx b/ui/src/Components/AlertHistory/index.test.tsx
index a4193f4ec..923acbdc7 100644
--- a/ui/src/Components/AlertHistory/index.test.tsx
+++ b/ui/src/Components/AlertHistory/index.test.tsx
@@ -6,6 +6,7 @@ import fetchMock from "@fetch-mock/jest";
 
 import { useInView } from "react-intersection-observer";
 
+import { mockInViewResponse } from "__fixtures__/InView";
 import { MockAlertGroup, MockAlert } from "__fixtures__/Alerts";
 import {
   EmptyHistoryResponse,
@@ -289,10 +290,9 @@ describe("<AlertHistory />", () => {
       },
     );
 
-    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue([
-      jest.fn(),
-      false,
-    ] as any);
+    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue(
+      mockInViewResponse(false),
+    );
 
     MockAlerts(3);
     const { unmount } = render(
@@ -320,10 +320,9 @@ describe("<AlertHistory />", () => {
       },
     );
 
-    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue([
-      jest.fn(),
-      false,
-    ] as any);
+    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue(
+      mockInViewResponse(false),
+    );
 
     MockAlerts(3);
     const { rerender, unmount } = render(
@@ -334,10 +333,9 @@ describe("<AlertHistory />", () => {
     });
     expect(fetchMock.callHistory.calls()).toHaveLength(0);
 
-    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue([
-      jest.fn(),
-      true,
-    ] as any);
+    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue(
+      mockInViewResponse(true),
+    );
 
     rerender(<AlertHistory group={group} grid={grid}></AlertHistory>);
     await act(async () => {
@@ -361,11 +359,9 @@ describe("<AlertHistory />", () => {
       },
     );
 
-    const inView = true;
-    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue([
-      jest.fn(),
-      inView,
-    ] as any);
+    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue(
+      mockInViewResponse(true),
+    );
 
     MockAlerts(3);
     const { unmount } = render(
diff --git a/ui/src/Components/MainModal/Configuration/AlertGroupCollapseConfiguration.test.tsx b/ui/src/Components/MainModal/Configuration/AlertGroupCollapseConfiguration.test.tsx
index b6adec6ba..ba6b1a94d 100644
--- a/ui/src/Components/MainModal/Configuration/AlertGroupCollapseConfiguration.test.tsx
+++ b/ui/src/Components/MainModal/Configuration/AlertGroupCollapseConfiguration.test.tsx
@@ -1,7 +1,7 @@
 import { render, fireEvent, waitFor } from "@testing-library/react";
 
 import { MockThemeContext } from "__fixtures__/Theme";
-import { Settings } from "Stores/Settings";
+import { Settings, type CollapseStateT } from "Stores/Settings";
 import { ThemeContext } from "Components/Theme";
 import { AlertGroupCollapseConfiguration } from "./AlertGroupCollapseConfiguration";
 
@@ -26,7 +26,9 @@ describe("<AlertGroupCollapseConfiguration />", () => {
   });
 
   it("resets stored config to defaults if it is invalid", async () => {
-    settingsStore.alertGroupConfig.setDefaultCollapseState("foo" as any);
+    settingsStore.alertGroupConfig.setDefaultCollapseState(
+      "foo" as unknown as CollapseStateT,
+    );
     const { container } = renderConfiguration();
     const select = container.querySelector("div.react-select__value-container");
     expect(select?.textContent).toBe(
diff --git a/ui/src/Components/MainModal/Configuration/AlertGroupSortConfiguration.test.tsx b/ui/src/Components/MainModal/Configuration/AlertGroupSortConfiguration.test.tsx
index 8faeff5a5..ec4966889 100644
--- a/ui/src/Components/MainModal/Configuration/AlertGroupSortConfiguration.test.tsx
+++ b/ui/src/Components/MainModal/Configuration/AlertGroupSortConfiguration.test.tsx
@@ -2,7 +2,7 @@ import { render, fireEvent } from "@testing-library/react";
 
 import { MockThemeContext } from "__fixtures__/Theme";
 import { useFetchGetMock } from "__fixtures__/useFetchGet";
-import { Settings } from "Stores/Settings";
+import { Settings, type SortOrderT } from "Stores/Settings";
 import { ThemeContext } from "Components/Theme";
 import { AlertGroupSortConfiguration } from "./AlertGroupSortConfiguration";
 
@@ -43,7 +43,7 @@ describe("<AlertGroupSortConfiguration />", () => {
   });
 
   it("invalid sortOrder value is reset on mount", () => {
-    settingsStore.gridConfig.setSortOrder("badValue" as any);
+    settingsStore.gridConfig.setSortOrder("badValue" as unknown as SortOrderT);
     renderConfiguration();
     expect(settingsStore.gridConfig.config.sortOrder).toBe(
       settingsStore.gridConfig.options.default.value,
diff --git a/ui/src/Components/Modal/index.test.tsx b/ui/src/Components/Modal/index.test.tsx
index 35eba924f..20091a5ef 100644
--- a/ui/src/Components/Modal/index.test.tsx
+++ b/ui/src/Components/Modal/index.test.tsx
@@ -145,7 +145,7 @@ describe("<ModalInner />", () => {
 
   it("scroll isn't enabled if ref is null", () => {
     const useRefSpy = jest.spyOn(React, "useRef").mockImplementation(() =>
-      Object.defineProperty({} as any, "current", {
+      Object.defineProperty({} as { current: unknown }, "current", {
         get: () => null,
         set: () => {},
       }),
diff --git a/ui/src/Components/NavBar/FilterInput/History.test.tsx b/ui/src/Components/NavBar/FilterInput/History.test.tsx
index ea0133b13..96c58e33d 100644
--- a/ui/src/Components/NavBar/FilterInput/History.test.tsx
+++ b/ui/src/Components/NavBar/FilterInput/History.test.tsx
@@ -345,7 +345,7 @@ describe("History localStorage", () => {
   it("localStored persists observable changes to localStorage", () => {
     const { localStored } = require("Common/LocalStore");
     const { runInAction } = require("mobx");
-    const store = localStored("test_persist_key", { filters: [] as any[] });
+    const store = localStored("test_persist_key", { filters: [] as unknown[] });
 
     // Flush the initial write (reaction fires via setTimeout 0)
     jest.runAllTimers();
diff --git a/ui/src/ErrorBoundary.test.tsx b/ui/src/ErrorBoundary.test.tsx
index 7ec6eec74..faf394ff4 100644
--- a/ui/src/ErrorBoundary.test.tsx
+++ b/ui/src/ErrorBoundary.test.tsx
@@ -4,7 +4,7 @@ import { render, screen } from "@testing-library/react";
 
 import { ErrorBoundary } from "./ErrorBoundary";
 
-let consoleSpy: any;
+let consoleSpy: jest.SpyInstance;
 
 beforeEach(() => {
   jest.useFakeTimers();
@@ -76,7 +76,7 @@ describe("<ErrorBoundary />", () => {
     // Verifies that reloadApp uses functional setState to decrement reloadSeconds
     const boundary = new ErrorBoundary({ children: <span /> });
     const setStateSpy = jest.spyOn(boundary, "setState");
-    (boundary as any).state = { cachedError: null, reloadSeconds: 2 };
+    boundary.state = { cachedError: null, reloadSeconds: 2 };
 
     boundary.reloadApp();
 
@@ -91,7 +91,7 @@ describe("<ErrorBoundary />", () => {
     // Verifies that reloadApp calls window.location.reload when reloadSeconds <= 1 (line 65)
     const boundary = new ErrorBoundary({ children: <span /> });
     const setStateSpy = jest.spyOn(boundary, "setState");
-    (boundary as any).state = { cachedError: null, reloadSeconds: 1 };
+    boundary.state = { cachedError: null, reloadSeconds: 1 };
 
     boundary.reloadApp();
 
@@ -103,7 +103,7 @@ describe("<ErrorBoundary />", () => {
     const boundary = new ErrorBoundary({ children: <span /> });
     const setStateSpy = jest.spyOn(boundary, "setState");
     const error = new Error("Test error");
-    (boundary as any).state = { cachedError: error, reloadSeconds: 60 };
+    boundary.state = { cachedError: error, reloadSeconds: 60 };
 
     boundary.componentDidCatch(error, { componentStack: "" });
 
@@ -115,7 +115,7 @@ describe("<ErrorBoundary />", () => {
     const boundary = new ErrorBoundary({ children: <span /> });
     const setIntervalSpy = jest.spyOn(global, "setInterval");
     const error = new Error("Test error");
-    (boundary as any).timer = 123;
+    boundary.timer = 123 as unknown as ReturnType<typeof setInterval>;
 
     boundary.componentDidCatch(error, { componentStack: "" });
 
diff --git a/ui/src/Hooks/useFetchGet.test.tsx b/ui/src/Hooks/useFetchGet.test.tsx
index 0caf977d4..f7e5a939d 100644
--- a/ui/src/Hooks/useFetchGet.test.tsx
+++ b/ui/src/Hooks/useFetchGet.test.tsx
@@ -511,7 +511,7 @@ describe("useFetchGet", () => {
           });
           return "ok";
         },
-      } as any);
+      } as unknown as Response);
     jest.useRealTimers();
 
     const Component = () => {
diff --git a/ui/src/Hooks/useFlashTransition.test.tsx b/ui/src/Hooks/useFlashTransition.test.tsx
index a3bc81157..b1d9e5fdd 100644
--- a/ui/src/Hooks/useFlashTransition.test.tsx
+++ b/ui/src/Hooks/useFlashTransition.test.tsx
@@ -4,6 +4,8 @@ import { renderHook } from "@testing-library/react";
 
 import { useInView } from "react-intersection-observer";
 
+import { mockInViewResponse } from "__fixtures__/InView";
+
 import { useFlashTransition, defaultProps } from "./useFlashTransition";
 
 describe("useFlashTransition", () => {
@@ -12,10 +14,9 @@ describe("useFlashTransition", () => {
   });
 
   it("does nothing when value changes but element is out of viewport", () => {
-    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue([
-      jest.fn(),
-      false,
-    ] as any);
+    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue(
+      mockInViewResponse(false),
+    );
 
     let value = 0;
     const { result, rerender } = renderHook(() => useFlashTransition(value));
@@ -27,10 +28,9 @@ describe("useFlashTransition", () => {
   });
 
   it("flashes when value changes and element is in viewport", () => {
-    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue([
-      jest.fn(),
-      true,
-    ] as any);
+    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue(
+      mockInViewResponse(true),
+    );
 
     let value = 2;
     const { result, rerender } = renderHook(() => useFlashTransition(value));
@@ -46,10 +46,9 @@ describe("useFlashTransition", () => {
   });
 
   it("flashes when value changes and element moves into viewport", () => {
-    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue([
-      jest.fn(),
-      false,
-    ] as any);
+    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue(
+      mockInViewResponse(false),
+    );
 
     let value = 2;
     const { result, rerender } = renderHook(() => useFlashTransition(value));
@@ -59,10 +58,9 @@ describe("useFlashTransition", () => {
     expect(result.current.props).toMatchObject(defaultProps);
 
     act(() => {
-      (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue([
-        jest.fn(),
-        true,
-      ] as any);
+      (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue(
+        mockInViewResponse(true),
+      );
     });
     rerender();
     expect(result.current.props).toMatchObject({
@@ -73,10 +71,9 @@ describe("useFlashTransition", () => {
   });
 
   it("stops flashing props.onEntered is called", () => {
-    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue([
-      jest.fn(),
-      true,
-    ] as any);
+    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue(
+      mockInViewResponse(true),
+    );
 
     let value = 2;
     const { result, rerender } = renderHook(() => useFlashTransition(value));
@@ -89,25 +86,23 @@ describe("useFlashTransition", () => {
       enter: true,
     });
 
-    act(() => (result.current.props as any).onEntered());
+    act(() => result.current.props.onEntered!({} as HTMLElement, false));
     expect(result.current.props).toMatchObject(defaultProps);
   });
 
   it("unmounts cleanly when not flashing", () => {
-    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue([
-      jest.fn(),
-      false,
-    ] as any);
+    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue(
+      mockInViewResponse(false),
+    );
 
     const { unmount } = renderHook(() => useFlashTransition(4));
     unmount();
   });
 
   it("unmounts cleanly when flashing", () => {
-    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue([
-      jest.fn(),
-      false,
-    ] as any);
+    (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue(
+      mockInViewResponse(false),
+    );
 
     let value = 5;
     const { rerender, unmount } = renderHook(() => useFlashTransition(value));
diff --git a/ui/src/Stores/AlertStore.test.ts b/ui/src/Stores/AlertStore.test.ts
index 9597da954..2f733d049 100644
--- a/ui/src/Stores/AlertStore.test.ts
+++ b/ui/src/Stores/AlertStore.test.ts
@@ -12,7 +12,7 @@ import {
   NewUnappliedFilter,
 } from "Stores/AlertStore";
 
-declare let global: any;
+declare let global: typeof globalThis;
 
 beforeEach(() => {
   fetchMock.mockReset();
@@ -491,12 +491,16 @@ describe("UpdateLocationSearch", () => {
   });
 
   it("{a: foo} is not pushed to location.search", () => {
-    UpdateLocationSearch({ a: "foo" } as any);
+    UpdateLocationSearch({ a: "foo" } as unknown as Parameters<
+      typeof UpdateLocationSearch
+    >[0]);
     expect(window.location.search).toBe("?q=");
   });
 
   it("{a: foo, q: bar} is pushed to location.search", () => {
-    UpdateLocationSearch({ a: "foo", q: ["bar"] } as any);
+    UpdateLocationSearch({ a: "foo", q: ["bar"] } as unknown as Parameters<
+      typeof UpdateLocationSearch
+    >[0]);
     expect(window.location.search).toBe("?q=bar");
   });
 
@@ -649,7 +653,7 @@ describe("AlertStore.fetch", () => {
           type: "opaque",
           body: "auth needed",
           json: jest.fn(() => EmptyAPIResponse()),
-        }) as any,
+        }) as unknown as Promise<Response>,
     );
 
     await expect(
@@ -685,7 +689,9 @@ describe("AlertStore.fetch", () => {
     const store = new AlertStore(["label=value"]);
 
     // initial fetch, should update settings
-    store.settings.setValues({ foo: "bar" } as any);
+    store.settings.setValues({ foo: "bar" } as unknown as Parameters<
+      typeof store.settings.setValues
+    >[0]);
     await expect(
       store.fetch("", false, "", "", false, {}, 5, {}),
     ).resolves.toBeUndefined();
diff --git a/ui/src/__fixtures__/InView.ts b/ui/src/__fixtures__/InView.ts
new file mode 100644
index 000000000..b2a523bbc
--- /dev/null
+++ b/ui/src/__fixtures__/InView.ts
@@ -0,0 +1,13 @@
+import type { InViewHookResponse } from "react-intersection-observer";
+
+const mockInViewResponse = (inView: boolean): InViewHookResponse => {
+  const ref = jest.fn() as (node?: Element | null) => void;
+  const response = Object.assign([ref, inView, undefined] as const, {
+    ref,
+    inView,
+    entry: undefined,
+  });
+  return response as unknown as InViewHookResponse;
+};
+
+export { mockInViewResponse };
diff --git a/ui/src/index.test.tsx b/ui/src/index.test.tsx
index db9714407..b0b913913 100644
--- a/ui/src/index.test.tsx
+++ b/ui/src/index.test.tsx
@@ -20,11 +20,12 @@ import { EmptyAPIResponse } from "__fixtures__/Fetch";
 import { DefaultsBase64 } from "__fixtures__/Defaults";
 import { mockMatchMedia } from "__fixtures__/matchMedia";
 
-const settingsElement = {
-  dataset: {
-    defaultFiltersBase64: "WyJmb289YmFyIiwiYmFyPX5iYXoiXQ==",
-  },
-};
+const settingsElement = document.createElement("span");
+settingsElement.dataset.defaultFiltersBase64 =
+  "WyJmb289YmFyIiwiYmFyPX5iYXoiXQ==";
+
+const defaultsElement = document.createElement("span");
+defaultsElement.innerHTML = DefaultsBase64;
 
 beforeEach(() => {
   window.matchMedia = mockMatchMedia({});
@@ -41,7 +42,7 @@ it("renders without crashing with missing defaults div", async () => {
     .spyOn(global.document, "getElementById")
     .mockImplementation((name: string) => {
       return name === "settings"
-        ? (settingsElement as any)
+        ? settingsElement
         : name === "defaults"
           ? null
           : name === "root"
@@ -71,11 +72,9 @@ it("renders without crashing with defaults present", async () => {
     .spyOn(global.document, "getElementById")
     .mockImplementation((name: string) => {
       return name === "settings"
-        ? (settingsElement as any)
+        ? settingsElement
         : name === "defaults"
-          ? {
-              innerHTML: DefaultsBase64,
-            }
+          ? defaultsElement
           : name === "root"
             ? root
             : null;
diff --git a/ui/src/setupTests.ts b/ui/src/setupTests.ts
index 488d2a969..8a3c485d6 100644
--- a/ui/src/setupTests.ts
+++ b/ui/src/setupTests.ts
@@ -1,11 +1,11 @@
-import React from "react";
-
 import "@testing-library/jest-dom";
 
 import fetchMock, { manageFetchMockGlobally } from "@fetch-mock/jest";
 
 import { useInView } from "react-intersection-observer";
 
+import { mockInViewResponse } from "__fixtures__/InView";
+
 import { createMocks as createIdleTimerMocks } from "react-idle-timer";
 
 import { configure } from "mobx";
@@ -35,9 +35,6 @@ jest.mock("react-intersection-observer");
 FetchRetryConfig.minTimeout = 2;
 FetchRetryConfig.maxTimeout = 10;
 
-// floating-ui uses useLayoutEffect
-React.useLayoutEffect = React.useEffect;
-
 // Fail tests on any console output except explicitly allowed messages
 const allowedMessages = [
   // React.lazy suspended resource warnings (React 19 testing limitation)
@@ -66,9 +63,7 @@ beforeEach(() => {
     useFetchGet as jest.MockedFunction<typeof useFetchGetMock>
   ).mockImplementation(useFetchGetMock);
 
-  (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue([
-    jest.fn(),
-    true,
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  ] as any);
+  (useInView as jest.MockedFunction<typeof useInView>).mockReturnValue(
+    mockInViewResponse(true),
+  );
 });
diff --git a/ui/src/testEnvironment.ts b/ui/src/testEnvironment.ts
index 74f04f015..bb52b2c30 100644
--- a/ui/src/testEnvironment.ts
+++ b/ui/src/testEnvironment.ts
@@ -7,6 +7,11 @@ class ResizeObserverPolyfill {
   disconnect() {}
 }
 
+interface GlobalWithResizeObserver {
+  ResizeObserver: typeof ResizeObserverPolyfill;
+  window: { ResizeObserver: typeof ResizeObserverPolyfill };
+}
+
 export default class CustomTestEnvironment extends TestEnvironment {
   async setup() {
     await super.setup();
@@ -14,11 +19,8 @@ export default class CustomTestEnvironment extends TestEnvironment {
     this.global.Response = Response;
     this.global.ReadableStream = ReadableStream;
     this.global.fetch = fetch;
-    // Polyfill ResizeObserver for react-cool-dimensions (checks window.ResizeObserver)
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    (this.global as any).ResizeObserver = ResizeObserverPolyfill;
-    // Also set on window for libraries that check window.ResizeObserver
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    (this.global as any).window.ResizeObserver = ResizeObserverPolyfill;
+    const g = this.global as unknown as GlobalWithResizeObserver;
+    g.ResizeObserver = ResizeObserverPolyfill;
+    g.window.ResizeObserver = ResizeObserverPolyfill;
   }
 }