From 55fe9e9c0cf044b4724f62751f5024b297e98807 Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Thu, 15 Oct 2026 01:00:25 +0000
Subject: [PATCH 1/2] fix(web): restore go-to-today now-cue pulse on repeated t
 presses

Co-authored-by: Tyler Dane <tyler-dane@users.noreply.github.com>
---
 .../src/common/utils/grid/grid.util.ts        | 33 +++++++++++--
 .../src/components/SelectView/SelectView.tsx  |  3 ++
 .../src/grid/components/TimedGrid.tsx         |  8 ++--
 .../src/grid/now-cue/now-cue.store.test.ts    | 48 +++++++++++++++++++
 .../src/grid/now-cue/now-cue.store.ts         | 26 +++++++---
 .../now-cue/scroll-to-now-or-pulse.test.ts    | 44 ++++++++++++++++-
 .../grid/now-cue/scroll-to-now-or-pulse.ts    | 21 +++++++-
 apps/calendar-web/src/index.css               | 14 ++++--
 .../Week/components/Header/DayLabels.test.tsx | 20 +++++++-
 .../Week/components/Header/DayLabels.tsx      |  4 ++
 e2e/now-cue-pulse.spec.ts                     | 33 +++++++++++++
 11 files changed, 230 insertions(+), 24 deletions(-)
 create mode 100644 apps/calendar-web/src/grid/now-cue/now-cue.store.test.ts
 create mode 100644 e2e/now-cue-pulse.spec.ts

diff --git a/apps/calendar-web/src/common/utils/grid/grid.util.ts b/apps/calendar-web/src/common/utils/grid/grid.util.ts
index 77feb3590..90f973bb7 100644
--- a/apps/calendar-web/src/common/utils/grid/grid.util.ts
+++ b/apps/calendar-web/src/common/utils/grid/grid.util.ts
@@ -63,14 +63,37 @@ export const SCROLL_TO_NOW_BUFFER_PX = 150;
 
 const SCROLL_TO_NOW_TOLERANCE_PX = 2;
 
+/** When the now line is visible and scroll is within this window, "t" pulses. */
+export const SCROLL_TO_NOW_PULSE_NEAR_MINUTES = 5;
+
 export const getScrollToNowTop = (clientHeight: number) =>
-  getCurrentMinute() * getMinuteHeight(clientHeight) - SCROLL_TO_NOW_BUFFER_PX;
+  Math.max(
+    0,
+    getCurrentMinute() * getMinuteHeight(clientHeight) -
+      SCROLL_TO_NOW_BUFFER_PX,
+  );
 
-export const isTimedGridScrolledToNow = (timedGrid: HTMLElement) => {
+export const getScrollToNowDelta = (timedGrid: HTMLElement) => {
   const targetTop = getScrollToNowTop(timedGrid.clientHeight);
-  return (
-    Math.abs(timedGrid.scrollTop - targetTop) <= SCROLL_TO_NOW_TOLERANCE_PX
-  );
+  return Math.abs(timedGrid.scrollTop - targetTop);
+};
+
+export const isTimedGridScrolledToNow = (timedGrid: HTMLElement) => {
+  return getScrollToNowDelta(timedGrid) <= SCROLL_TO_NOW_TOLERANCE_PX;
+};
+
+export const isTimedGridNearScrollToNow = (timedGrid: HTMLElement) => {
+  const nearPx =
+    getMinuteHeight(timedGrid.clientHeight) * SCROLL_TO_NOW_PULSE_NEAR_MINUTES;
+  return getScrollToNowDelta(timedGrid) <= nearPx;
+};
+
+/** Whether the live now line sits inside the timed grid's visible scroll area. */
+export const isNowLineInTimedGridViewport = (timedGrid: HTMLElement) => {
+  const nowLineY = getCurrentMinute() * getMinuteHeight(timedGrid.clientHeight);
+  const viewTop = timedGrid.scrollTop;
+  const viewBottom = viewTop + timedGrid.clientHeight;
+  return nowLineY >= viewTop && nowLineY <= viewBottom;
 };
 
 /** Returns true when the grid scroll position changed. */
diff --git a/apps/calendar-web/src/components/SelectView/SelectView.tsx b/apps/calendar-web/src/components/SelectView/SelectView.tsx
index 4b9ec76d1..47de58fef 100644
--- a/apps/calendar-web/src/components/SelectView/SelectView.tsx
+++ b/apps/calendar-web/src/components/SelectView/SelectView.tsx
@@ -20,6 +20,7 @@ import { Z_INDEX_FLOATING_MENU } from "@web/common/constants/web.constants";
 import { ShortcutKeys } from "@web/components/Shortcuts/ShortcutKeys";
 import {
   selectNowCueActive,
+  selectNowCuePulseGeneration,
   useNowCueStore,
 } from "@web/grid/now-cue/now-cue.store";
 import { useFloatingLayer } from "@web/shortcuts/floating-layer";
@@ -52,6 +53,7 @@ export const SelectView = ({
   const listRef = useRef<Array<HTMLElement | null>>([]);
   useFloatingLayer("viewSelect", isOpen);
   const pulseDayLabel = useNowCueStore(selectNowCueActive) && emphasizeDayLabel;
+  const pulseGeneration = useNowCueStore(selectNowCuePulseGeneration);
 
   const getCurrentView = (): "Day" | "Week" | "Life" => {
     const pathname = location.pathname;
@@ -190,6 +192,7 @@ export const SelectView = ({
               pulseDayLabel &&
                 "c-now-cue-label-pulse motion-reduce:transition-none",
             )}
+            key={emphasizeDayLabel ? pulseGeneration : undefined}
           >
             {label}
           </span>
diff --git a/apps/calendar-web/src/grid/components/TimedGrid.tsx b/apps/calendar-web/src/grid/components/TimedGrid.tsx
index c0a201f16..31682d466 100644
--- a/apps/calendar-web/src/grid/components/TimedGrid.tsx
+++ b/apps/calendar-web/src/grid/components/TimedGrid.tsx
@@ -25,6 +25,7 @@ import {
 import { useGridMarginLeft } from "@web/grid/grid-margin";
 import {
   selectNowCueActive,
+  selectNowCuePulseGeneration,
   useNowCueStore,
 } from "@web/grid/now-cue/now-cue.store";
 import { type GridVisibleDate } from "@web/grid/types/grid.types";
@@ -173,19 +174,18 @@ const CalendarNowLine = ({
   useMinuteTick();
   const percentOfDay = getCurrentPercentOfDay(effectiveTimeZone);
   const pulseNowLine = useNowCueStore(selectNowCueActive);
+  const pulseGeneration = useNowCueStore(selectNowCuePulseGeneration);
 
   return (
     <div
       aria-hidden="true"
       className={cn(
-        "absolute h-px motion-reduce:transition-none",
+        "c-now-line-rim absolute h-px motion-reduce:transition-none",
         pulseNowLine && "c-now-cue-pulse",
       )}
+      key={pulseGeneration}
       style={{
         background: accentGradient,
-        // Paper-colored rim: invisible on the grid, keeps the line readable
-        // where it crosses an event card filled with the accent color.
-        boxShadow: "0 0 0 1px var(--background)",
         top: `${percentOfDay}%`,
         left: `calc(${columnIndex} * 100% / ${columnCount})`,
         width: `calc(100% / ${columnCount})`,
diff --git a/apps/calendar-web/src/grid/now-cue/now-cue.store.test.ts b/apps/calendar-web/src/grid/now-cue/now-cue.store.test.ts
new file mode 100644
index 000000000..e15943773
--- /dev/null
+++ b/apps/calendar-web/src/grid/now-cue/now-cue.store.test.ts
@@ -0,0 +1,48 @@
+import {
+  NOW_CUE_PULSE_MS,
+  nowCueActions,
+  useNowCueStore,
+} from "@web/grid/now-cue/now-cue.store";
+import { afterEach, describe, expect, it } from "bun:test";
+
+describe("nowCueActions.pulse", () => {
+  afterEach(() => {
+    nowCueActions.resetForTests();
+  });
+
+  it("activates the cue and clears after the pulse duration", () => {
+    nowCueActions.pulse();
+
+    expect(useNowCueStore.getState().active).toBe(true);
+    expect(useNowCueStore.getState().pulseGeneration).toBe(1);
+
+    nowCueActions.resetForTests();
+    expect(useNowCueStore.getState().active).toBe(false);
+  });
+
+  it("bumps pulseGeneration on every press so animations can restart", () => {
+    nowCueActions.pulse();
+    nowCueActions.pulse();
+    nowCueActions.pulse();
+
+    expect(useNowCueStore.getState().pulseGeneration).toBe(3);
+    expect(useNowCueStore.getState().active).toBe(true);
+  });
+
+  it("extends the active window when pulsed again before it ends", () => {
+    nowCueActions.pulse();
+    nowCueActions.pulse();
+
+    expect(useNowCueStore.getState().pulseGeneration).toBe(2);
+
+    nowCueActions.resetForTests();
+    expect(useNowCueStore.getState().active).toBe(false);
+    expect(useNowCueStore.getState().pulseGeneration).toBe(0);
+  });
+});
+
+describe("NOW_CUE_PULSE_MS", () => {
+  it("matches the CSS animation duration", () => {
+    expect(NOW_CUE_PULSE_MS).toBe(700);
+  });
+});
diff --git a/apps/calendar-web/src/grid/now-cue/now-cue.store.ts b/apps/calendar-web/src/grid/now-cue/now-cue.store.ts
index 4dc7ae85a..aa893f846 100644
--- a/apps/calendar-web/src/grid/now-cue/now-cue.store.ts
+++ b/apps/calendar-web/src/grid/now-cue/now-cue.store.ts
@@ -7,9 +7,14 @@ export const NOW_CUE_PULSE_MS = 700;
 type NowCueState = {
   /** True for {@link NOW_CUE_PULSE_MS} after an already-at-now teach pulse. */
   active: boolean;
+  /** Increments on every pulse so CSS animations can restart on repeated presses. */
+  pulseGeneration: number;
 };
 
-export const initialNowCueState: NowCueState = { active: false };
+export const initialNowCueState: NowCueState = {
+  active: false,
+  pulseGeneration: 0,
+};
 
 let pulseTimer: ReturnType<typeof globalThis.setTimeout> | undefined;
 
@@ -26,14 +31,21 @@ const clearPulseTimer = () => {
   pulseTimer = undefined;
 };
 
+const schedulePulseEnd = () => {
+  pulseTimer = globalThis.setTimeout(() => {
+    pulseTimer = undefined;
+    useNowCueStore.setState({ active: false }, false, { type: "pulse-end" });
+  }, NOW_CUE_PULSE_MS);
+};
+
 export const nowCueActions = {
   pulse: () => {
     clearPulseTimer();
-    useNowCueStore.setState({ active: true }, false, { type: "pulse" });
-    pulseTimer = globalThis.setTimeout(() => {
-      pulseTimer = undefined;
-      useNowCueStore.setState({ active: false }, false, { type: "pulse-end" });
-    }, NOW_CUE_PULSE_MS);
+    const pulseGeneration = useNowCueStore.getState().pulseGeneration + 1;
+    useNowCueStore.setState({ active: true, pulseGeneration }, false, {
+      type: "pulse",
+    });
+    schedulePulseEnd();
   },
   resetForTests: () => {
     clearPulseTimer();
@@ -42,3 +54,5 @@ export const nowCueActions = {
 };
 
 export const selectNowCueActive = (state: NowCueState) => state.active;
+export const selectNowCuePulseGeneration = (state: NowCueState) =>
+  state.pulseGeneration;
diff --git a/apps/calendar-web/src/grid/now-cue/scroll-to-now-or-pulse.test.ts b/apps/calendar-web/src/grid/now-cue/scroll-to-now-or-pulse.test.ts
index b3334cc37..fffdfcb16 100644
--- a/apps/calendar-web/src/grid/now-cue/scroll-to-now-or-pulse.test.ts
+++ b/apps/calendar-web/src/grid/now-cue/scroll-to-now-or-pulse.test.ts
@@ -1,4 +1,7 @@
-import { getScrollToNowTop } from "@web/common/utils/grid/grid.util";
+import {
+  getMinuteHeight,
+  getScrollToNowTop,
+} from "@web/common/utils/grid/grid.util";
 import { nowCueActions, useNowCueStore } from "@web/grid/now-cue/now-cue.store";
 import { scrollToNowOrPulse } from "@web/grid/now-cue/scroll-to-now-or-pulse";
 import { afterEach, describe, expect, it, mock, setSystemTime } from "bun:test";
@@ -24,5 +27,44 @@ describe("scrollToNowOrPulse", () => {
 
     expect(scroll).not.toHaveBeenCalled();
     expect(useNowCueStore.getState().active).toBe(true);
+    expect(useNowCueStore.getState().pulseGeneration).toBe(1);
+  });
+
+  it("pulses when the now line is in view and scroll is near the teach target", () => {
+    setSystemTime(new Date("2026-02-05T12:00:00.000Z"));
+
+    const clientHeight = 1440;
+    const scroll = mock(() => {});
+    const targetTop = getScrollToNowTop(clientHeight);
+    const minuteHeight = getMinuteHeight(clientHeight);
+    const grid = {
+      clientHeight,
+      scrollTop: targetTop + minuteHeight * 2,
+      scroll,
+    } as unknown as HTMLElement;
+
+    scrollToNowOrPulse(grid);
+
+    expect(scroll).toHaveBeenCalled();
+    expect(useNowCueStore.getState().active).toBe(true);
+    expect(useNowCueStore.getState().pulseGeneration).toBe(1);
+  });
+
+  it("increments pulseGeneration on repeated already-at-now presses", () => {
+    setSystemTime(new Date("2026-02-05T12:00:00.000Z"));
+
+    const clientHeight = 1440;
+    const scroll = mock(() => {});
+    const grid = {
+      clientHeight,
+      scrollTop: getScrollToNowTop(clientHeight),
+      scroll,
+    } as unknown as HTMLElement;
+
+    scrollToNowOrPulse(grid);
+    scrollToNowOrPulse(grid);
+
+    expect(scroll).not.toHaveBeenCalled();
+    expect(useNowCueStore.getState().pulseGeneration).toBe(2);
   });
 });
diff --git a/apps/calendar-web/src/grid/now-cue/scroll-to-now-or-pulse.ts b/apps/calendar-web/src/grid/now-cue/scroll-to-now-or-pulse.ts
index c11d5840b..559e6d227 100644
--- a/apps/calendar-web/src/grid/now-cue/scroll-to-now-or-pulse.ts
+++ b/apps/calendar-web/src/grid/now-cue/scroll-to-now-or-pulse.ts
@@ -1,4 +1,9 @@
-import { scrollTimedGridToNow } from "@web/common/utils/grid/grid.util";
+import {
+  isNowLineInTimedGridViewport,
+  isTimedGridNearScrollToNow,
+  isTimedGridScrolledToNow,
+  scrollTimedGridToNow,
+} from "@web/common/utils/grid/grid.util";
 import { nowCueActions } from "@web/grid/now-cue/now-cue.store";
 
 export const scrollToNowOrPulse = (
@@ -7,7 +12,19 @@ export const scrollToNowOrPulse = (
 ) => {
   if (!timedGrid) return;
 
-  if (!scrollTimedGridToNow(timedGrid, behavior)) {
+  const strictAtNow = isTimedGridScrolledToNow(timedGrid);
+  const teachPulse =
+    strictAtNow ||
+    (isNowLineInTimedGridViewport(timedGrid) &&
+      isTimedGridNearScrollToNow(timedGrid));
+
+  if (teachPulse) {
+    if (!strictAtNow) {
+      scrollTimedGridToNow(timedGrid, behavior);
+    }
     nowCueActions.pulse();
+    return;
   }
+
+  scrollTimedGridToNow(timedGrid, behavior);
 };
diff --git a/apps/calendar-web/src/index.css b/apps/calendar-web/src/index.css
index 53a921861..bc61c1e28 100644
--- a/apps/calendar-web/src/index.css
+++ b/apps/calendar-web/src/index.css
@@ -267,7 +267,7 @@
   @keyframes nowCuePulse {
     0%,
     100% {
-      box-shadow: none;
+      box-shadow: 0 0 0 1px var(--color-background);
       opacity: 1;
     }
     45% {
@@ -281,12 +281,12 @@
   @keyframes nowCueLabelPulse {
     0%,
     100% {
-      color: inherit;
+      color: var(--color-accent);
       filter: brightness(1);
     }
     45% {
-      color: var(--color-accent);
-      filter: brightness(1.2);
+      color: var(--color-accent-hover);
+      filter: brightness(1.35);
     }
   }
 
@@ -297,7 +297,7 @@
       filter: brightness(1);
     }
     45% {
-      filter: brightness(1.35);
+      filter: brightness(1.45);
     }
   }
 
@@ -789,6 +789,10 @@
   @apply motion-reduce:animate-none;
 }
 
+@utility c-now-line-rim {
+  box-shadow: 0 0 0 1px var(--color-background);
+}
+
 @utility c-now-cue-pulse {
   animation: var(--animate-now-cue-pulse);
   @apply motion-reduce:animate-none;
diff --git a/apps/calendar-web/src/views/Week/components/Header/DayLabels.test.tsx b/apps/calendar-web/src/views/Week/components/Header/DayLabels.test.tsx
index ead64fb8b..a6ed5582b 100644
--- a/apps/calendar-web/src/views/Week/components/Header/DayLabels.test.tsx
+++ b/apps/calendar-web/src/views/Week/components/Header/DayLabels.test.tsx
@@ -1,4 +1,4 @@
-import { cleanup, render, screen } from "@testing-library/react";
+import { act, cleanup, render, screen } from "@testing-library/react";
 import dayjs from "@core/util/date/dayjs";
 import { nowCueActions, useNowCueStore } from "@web/grid/now-cue/now-cue.store";
 import { pageJumpHintActions } from "@web/shortcuts/page-jump/page-jump.store";
@@ -48,6 +48,24 @@ describe("DayLabels", () => {
     ).toBeNull();
   });
 
+  it("reapplies pulse classes when the now cue fires again", () => {
+    renderLabels();
+
+    act(() => {
+      nowCueActions.pulse();
+    });
+    expect(screen.getByText("Mon")).toHaveClass("c-now-cue-label-pulse");
+
+    act(() => {
+      nowCueActions.pulse();
+    });
+    expect(useNowCueStore.getState().pulseGeneration).toBe(2);
+    expect(screen.getByText("Mon")).toHaveClass("c-now-cue-label-pulse");
+    expect(screen.getByText("17")).toHaveClass(
+      "c-now-cue-label-gradient-pulse",
+    );
+  });
+
   it("shows the effective timezone in the grid corner", () => {
     renderLabels();
 
diff --git a/apps/calendar-web/src/views/Week/components/Header/DayLabels.tsx b/apps/calendar-web/src/views/Week/components/Header/DayLabels.tsx
index aba19c689..c1f54115d 100644
--- a/apps/calendar-web/src/views/Week/components/Header/DayLabels.tsx
+++ b/apps/calendar-web/src/views/Week/components/Header/DayLabels.tsx
@@ -12,6 +12,7 @@ import { EVENT_WIDTH_MINIMUM } from "@web/grid/grid.constants";
 import { useGridMarginLeft } from "@web/grid/grid-margin";
 import {
   selectNowCueActive,
+  selectNowCuePulseGeneration,
   useNowCueStore,
 } from "@web/grid/now-cue/now-cue.store";
 import {
@@ -55,6 +56,7 @@ export const DayLabels: FC<Props> = ({
     !isEventFormOpen && (pageJumpHintsVisible || isEventJumpActive);
   const marginLeft = useGridMarginLeft();
   const pulseTodayLabel = useNowCueStore(selectNowCueActive);
+  const pulseGeneration = useNowCueStore(selectNowCuePulseGeneration);
   const dayJumpHowTo = isEventJumpActive
     ? "Type the day key to focus that column."
     : "Hold Shift and press the day key to focus that column.";
@@ -128,6 +130,7 @@ export const DayLabels: FC<Props> = ({
                     pulseTodayLabel &&
                     "c-now-cue-label-gradient-pulse motion-reduce:transition-none",
                 )}
+                key={isToday ? `day-num-${pulseGeneration}` : undefined}
               >
                 {dayNumber}
               </span>
@@ -145,6 +148,7 @@ export const DayLabels: FC<Props> = ({
                       pulseTodayLabel &&
                       "c-now-cue-label-pulse motion-reduce:transition-none",
                   )}
+                  key={isToday ? `day-name-${pulseGeneration}` : undefined}
                 >
                   {day.format("ddd")}
                 </span>
diff --git a/e2e/now-cue-pulse.spec.ts b/e2e/now-cue-pulse.spec.ts
new file mode 100644
index 000000000..5a0bf089c
--- /dev/null
+++ b/e2e/now-cue-pulse.spec.ts
@@ -0,0 +1,33 @@
+import { expect, test } from "@playwright/test";
+import {
+  dispatchDocumentKey,
+  prepareTimedCalendarPage,
+} from "./utils/event-test-utils";
+
+test.describe("go-to-today now cue pulse", () => {
+  test("applies now-cue pulse classes on repeated t presses at now", async ({
+    page,
+  }) => {
+    await page.setViewportSize({ width: 1728, height: 1000 });
+    await prepareTimedCalendarPage(page);
+
+    const mainGrid = page.locator("#mainGrid");
+    await expect(mainGrid).toBeVisible();
+
+    const nowLine = mainGrid.locator(".c-now-line-rim").first();
+    await nowLine.waitFor({ state: "attached" });
+
+    await dispatchDocumentKey(page, "t");
+    await page.waitForTimeout(800);
+
+    await dispatchDocumentKey(page, "t");
+    await expect(nowLine).toHaveClass(/c-now-cue-pulse/);
+    await expect(nowLine).toHaveCSS("animation-name", "nowCuePulse");
+
+    await dispatchDocumentKey(page, "t");
+    await expect(nowLine).toHaveClass(/c-now-cue-pulse/);
+
+    const todayWeekday = page.getByText("Fri", { exact: true }).first();
+    await expect(todayWeekday).toHaveClass(/c-now-cue-label-pulse/);
+  });
+});

From 616e364c171630b1cb6dbd3360dd07623736fc47 Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Thu, 15 Oct 2026 01:55:18 +0000
Subject: [PATCH 2/2] test(web): pin grid height in scroll-to-now mount tests

Co-authored-by: Tyler Dane <tyler-dane@users.noreply.github.com>
---
 .../Calendar/DayCalendarGrid.test.tsx         |  7 ++++
 .../src/views/Week/WeekView.render.test.tsx   | 34 +++++++++++++++++--
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/apps/calendar-web/src/views/Day/components/Calendar/DayCalendarGrid.test.tsx b/apps/calendar-web/src/views/Day/components/Calendar/DayCalendarGrid.test.tsx
index e0467a9d3..176a915ab 100644
--- a/apps/calendar-web/src/views/Day/components/Calendar/DayCalendarGrid.test.tsx
+++ b/apps/calendar-web/src/views/Day/components/Calendar/DayCalendarGrid.test.tsx
@@ -758,10 +758,17 @@ describe("DayCalendarGrid", () => {
   });
 
   it("scrolls the Day timed grid to now when the Day view requests it", () => {
+    setSystemTime(new Date("2026-02-05T12:00:00.000Z"));
     const scroll = mock();
 
     HTMLElement.prototype.scroll = scroll;
     renderDayCalendarGrid();
+    const mainGrid = document.getElementById("mainGrid");
+    if (!(mainGrid instanceof HTMLElement)) {
+      throw new Error("expected main grid");
+    }
+    Object.defineProperty(mainGrid, "clientHeight", { value: 1440 });
+    mainGrid.scrollTop = 0;
     scroll.mockClear();
 
     emitViewCommand("SCROLL_TO_NOW_LINE");
diff --git a/apps/calendar-web/src/views/Week/WeekView.render.test.tsx b/apps/calendar-web/src/views/Week/WeekView.render.test.tsx
index 366b987c4..73baa001e 100644
--- a/apps/calendar-web/src/views/Week/WeekView.render.test.tsx
+++ b/apps/calendar-web/src/views/Week/WeekView.render.test.tsx
@@ -1,23 +1,51 @@
 import { type FC, useRef } from "react";
-import { describe, expect, it, spyOn } from "bun:test";
+import {
+  afterEach,
+  describe,
+  expect,
+  it,
+  setSystemTime,
+  spyOn,
+} from "bun:test";
 import "@testing-library/jest-dom";
 import { render } from "@testing-library/react";
 import { useScroll } from "@web/views/Week/hooks/grid/useScroll";
 
 describe("Scroll", () => {
+  afterEach(() => {
+    setSystemTime();
+  });
+
   it("only scrolls once", () => {
+    setSystemTime(new Date("2026-02-05T12:00:00.000Z"));
+
     const ScrollHarness: FC = () => {
       const ref = useRef<HTMLDivElement | null>(null);
       useScroll(ref);
       return <div ref={ref} />;
     };
 
+    const clientHeight = Object.getOwnPropertyDescriptor(
+      HTMLElement.prototype,
+      "clientHeight",
+    );
+    Object.defineProperty(HTMLElement.prototype, "clientHeight", {
+      configurable: true,
+      get: () => 1440,
+    });
+
     const scrollSpy = spyOn(window.HTMLElement.prototype, "scroll");
 
     render(<ScrollHarness />);
 
-    expect(scrollSpy).toHaveBeenCalled();
-    // A prototype spy outlives this file unless it is put back.
+    expect(scrollSpy).toHaveBeenCalledTimes(1);
     scrollSpy.mockRestore();
+    if (clientHeight) {
+      Object.defineProperty(
+        HTMLElement.prototype,
+        "clientHeight",
+        clientHeight,
+      );
+    }
   });
 });