From cf170214a6afd54a2604d5356fd305a539991331 Mon Sep 17 00:00:00 2001
From: dev_agent <dev_agent@cubecraftlabs.com>
Date: Wed, 30 Sep 2026 09:50:25 -0400
Subject: [PATCH] Format the panel and admin date and clock in the stored
 application timezone

The panel snapshot now carries the admin-saved `timezone` ("" when unset);
the coordinator threads it onto the household due-today sensor, and the
Party Board and Quest Log cards format their kicker, header and dock
date and clock in it, falling back to Home Assistant's zone only when
none is stored. The admin app loads the stored zone once
(AppTimezoneProvider) and uses it for completion clocks, History day
grouping, clocks and lateness, and "today" in Schedule, History and new
task defaults; Settings publishes a saved zone app-wide at once.

Resolves review finding TZ-001 (task 7e173881).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 admin/src/App.test.tsx                        |  53 +++++++--
 admin/src/App.tsx                             |  22 ++--
 admin/src/definitions/DefinitionsTab.test.tsx |  54 ++++++++-
 admin/src/definitions/DefinitionsTab.tsx      |  42 ++++---
 admin/src/history/HistoryTab.test.tsx         | 112 ++++++++++++++++++
 admin/src/history/HistoryTab.tsx              |  18 +--
 admin/src/history/format.ts                   |  45 ++++---
 admin/src/schedule/OverrideEditor.test.tsx    |   2 +
 admin/src/schedule/ScheduleTab.test.tsx       |  55 ++++++++-
 admin/src/schedule/ScheduleTab.tsx            |   9 +-
 admin/src/schedule/cycle.ts                   |   7 --
 admin/src/settings/SettingsScreen.test.tsx    |  40 +++++++
 admin/src/settings/SettingsScreen.tsx         |  10 +-
 admin/src/time/AppTimezone.tsx                |  91 ++++++++++++++
 admin/src/time/zone.test.ts                   |  60 ++++++++++
 admin/src/time/zone.ts                        |  79 ++++++++++++
 admin/src/today/TodayTab.test.tsx             |  54 +++++++++
 admin/src/today/TodayTab.tsx                  |   4 +-
 admin/src/today/format.ts                     |  14 ++-
 api/routes_panel.py                           |  12 +-
 custom_components/nestquest/coordinator.py    |   3 +
 custom_components/nestquest/core/snapshot.py  |   5 +
 custom_components/nestquest/sensor.py         |   3 +
 .../nestquest/www/nestquest-cards.js          |  60 ++++++----
 frontend/src/cards/party-board.ts             |  10 +-
 frontend/src/cards/quest-log.ts               |  10 +-
 frontend/tests/render-party-board.mjs         |  25 +++-
 tests/conftest.py                             |   1 +
 tests/test_api_admin_snapshot.py              |   6 +-
 tests/test_api_household_clock.py             |  18 +++
 tests/test_binary_sensors.py                  |   1 +
 tests/test_complete_quest_proxy.py            |   1 +
 tests/test_coordinator.py                     |   8 +-
 tests/test_core_snapshot.py                   |   1 +
 tests/test_entity_lifecycle.py                |   1 +
 tests/test_entity_matrix.py                   |   1 +
 tests/test_events.py                          |   1 +
 tests/test_panel_cards.py                     |  74 +++++++++++-
 tests/test_sensors.py                         |  17 +++
 tests/test_sse_subscription.py                |   7 +-
 40 files changed, 910 insertions(+), 126 deletions(-)
 create mode 100644 admin/src/time/AppTimezone.tsx
 create mode 100644 admin/src/time/zone.test.ts
 create mode 100644 admin/src/time/zone.ts

diff --git a/admin/src/App.test.tsx b/admin/src/App.test.tsx
index 7a38e6a..442f2ee 100644
--- a/admin/src/App.test.tsx
+++ b/admin/src/App.test.tsx
@@ -2,10 +2,28 @@ import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { cleanup, fireEvent, render, screen } from "@testing-library/react";
 import App from "./App";
 
+function jsonResponse(body: unknown, status = 200): Response {
+  return new Response(JSON.stringify(body), {
+    status,
+    headers: { "Content-Type": "application/json" },
+  });
+}
+
+let settingsResponse: () => Promise<Response>;
+
 describe("NestQuest Admin shell", () => {
   beforeEach(() => {
-    // The Today tab fetches the admin snapshot; keep the shell tests offline.
-    vi.stubGlobal("fetch", vi.fn(() => new Promise<Response>(() => {})));
+    settingsResponse = () => Promise.resolve(jsonResponse({ timezone: "" }));
+    // The shell loads the stored application timezone; every tab's own
+    // requests stay pending so the shell tests remain offline.
+    vi.stubGlobal(
+      "fetch",
+      vi.fn((url: string) =>
+        String(url).endsWith("/api/v1/admin/settings")
+          ? settingsResponse()
+          : new Promise<Response>(() => {}),
+      ),
+    );
   });
 
   afterEach(() => {
@@ -22,10 +40,10 @@ describe("NestQuest Admin shell", () => {
     }
   });
 
-  it("starts on the Today screen and switches on tab click", () => {
+  it("starts on the Today screen and switches on tab click", async () => {
     render(<App />);
 
-    expect(screen.getByRole("heading", { name: "Today" })).toBeTruthy();
+    expect(await screen.findByRole("heading", { name: "Today" })).toBeTruthy();
 
     fireEvent.click(screen.getByRole("tab", { name: "History" }));
 
@@ -36,12 +54,33 @@ describe("NestQuest Admin shell", () => {
     );
   });
 
-  it("the Tasks tab renders the definitions screen", () => {
+  it("the Tasks tab renders the definitions screen", async () => {
     render(<App />);
 
     fireEvent.click(screen.getByRole("tab", { name: "Tasks" }));
 
-    expect(screen.getByRole("heading", { name: "Tasks" })).toBeTruthy();
+    expect(await screen.findByRole("heading", { name: "Tasks" })).toBeTruthy();
     expect(screen.getByRole("tabpanel").textContent).not.toContain("placeholder");
   });
-});
\ No newline at end of file
+
+  it("renders no screen until the stored application timezone is known", async () => {
+    settingsResponse = () => new Promise<Response>(() => {});
+    render(<App />);
+
+    expect(screen.getByTestId("timezone-loading")).toBeTruthy();
+    expect(screen.queryByRole("heading", { name: "Today" })).toBeNull();
+  });
+
+  it("a failed timezone load says so and retries", async () => {
+    settingsResponse = () => Promise.resolve(jsonResponse({ detail: "boom" }, 500));
+    render(<App />);
+
+    await screen.findByTestId("timezone-error");
+    expect(screen.queryByRole("heading", { name: "Today" })).toBeNull();
+
+    settingsResponse = () => Promise.resolve(jsonResponse({ timezone: "Pacific/Auckland" }));
+    fireEvent.click(screen.getByRole("button", { name: "Try again" }));
+
+    expect(await screen.findByRole("heading", { name: "Today" })).toBeTruthy();
+  });
+});
diff --git a/admin/src/App.tsx b/admin/src/App.tsx
index 5f44fad..31ab78a 100644
--- a/admin/src/App.tsx
+++ b/admin/src/App.tsx
@@ -4,6 +4,7 @@ import { TransitionsProvider } from "./api/useTransitions";
 import DefinitionsTab from "./definitions/DefinitionsTab";
 import HistoryTab from "./history/HistoryTab";
 import ScheduleTab from "./schedule/ScheduleTab";
+import { AppTimezoneProvider } from "./time/AppTimezone";
 import TodayTab from "./today/TodayTab";
 
 const TABS = [
@@ -32,15 +33,18 @@ export default function App() {
           role="tabpanel"
           aria-labelledby={`tab-${active}`}
         >
-          {active === "today" ? (
-            <TodayTab />
-          ) : active === "tasks" ? (
-            <DefinitionsTab />
-          ) : active === "schedule" ? (
-            <ScheduleTab />
-          ) : (
-            <HistoryTab />
-          )}
+          {/* Every screen's local time is the stored application timezone. */}
+          <AppTimezoneProvider>
+            {active === "today" ? (
+              <TodayTab />
+            ) : active === "tasks" ? (
+              <DefinitionsTab />
+            ) : active === "schedule" ? (
+              <ScheduleTab />
+            ) : (
+              <HistoryTab />
+            )}
+          </AppTimezoneProvider>
         </main>
         <nav className="admin-tabbar" aria-label="Admin sections">
           {TABS.map((tab) => (
diff --git a/admin/src/definitions/DefinitionsTab.test.tsx b/admin/src/definitions/DefinitionsTab.test.tsx
index 3a24638..1337f13 100644
--- a/admin/src/definitions/DefinitionsTab.test.tsx
+++ b/admin/src/definitions/DefinitionsTab.test.tsx
@@ -1,4 +1,4 @@
-import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { afterAll, afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
 import { act, cleanup, fireEvent, render, screen, waitFor, within } from "@testing-library/react";
 import DefinitionsTab from "./DefinitionsTab";
 import {
@@ -12,6 +12,7 @@ import {
 } from "./definitionIcons";
 import type { AdminChild, DefinitionRule, QuestDefinition } from "../api/definitions";
 import { storeTokens } from "../auth/oidc";
+import { AppTimezoneProvider } from "../time/AppTimezone";
 
 function child(id: number, name: string, overrides: Partial<AdminChild> = {}): AdminChild {
   return {
@@ -1723,3 +1724,54 @@ describe("DefinitionsTab start date", () => {
     expect(within(s).getByText("Pick a start date.")).toBeTruthy();
   });
 });
+
+describe("DefinitionsTab start date in the stored application timezone", () => {
+  async function newSheetStartDate(timezone: string): Promise<string> {
+    api = fakeApi([BRUSH]);
+    vi.stubGlobal(
+      "fetch",
+      vi.fn((input: RequestInfo | URL, init?: RequestInit) =>
+        String(input).endsWith("/api/v1/admin/settings")
+          ? Promise.resolve(jsonResponse({ timezone }))
+          : api.fetchMock(input, init),
+      ),
+    );
+    render(
+      <AppTimezoneProvider>
+        <DefinitionsTab />
+      </AppTimezoneProvider>,
+    );
+    await screen.findByText("Brush teeth");
+    fireEvent.click(screen.getByRole("button", { name: "New" }));
+    return startDateInput(sheet()).value;
+  }
+
+  beforeAll(() => {
+    vi.stubEnv("TZ", "UTC");
+  });
+
+  afterAll(() => {
+    vi.unstubAllEnvs();
+  });
+
+  beforeEach(() => {
+    sessionStorage.clear();
+    storeTokens({ access_token: "at-123", expires_in: 600 });
+    // Wed 23 Sep 13:00 UTC is already Thu 24 Sep 01:00 in Auckland.
+    vi.useFakeTimers({ toFake: ["Date"], now: new Date("2026-09-23T13:00:00Z") });
+  });
+
+  afterEach(() => {
+    cleanup();
+    vi.unstubAllGlobals();
+    vi.useRealTimers();
+  });
+
+  it("a new task defaults to today in the stored zone", async () => {
+    expect(await newSheetStartDate("Pacific/Auckland")).toBe("2026-09-24");
+  });
+
+  it("an empty stored zone defaults to the browser's local today", async () => {
+    expect(await newSheetStartDate("")).toBe("2026-09-23");
+  });
+});
diff --git a/admin/src/definitions/DefinitionsTab.tsx b/admin/src/definitions/DefinitionsTab.tsx
index a3ff02a..bea4353 100644
--- a/admin/src/definitions/DefinitionsTab.tsx
+++ b/admin/src/definitions/DefinitionsTab.tsx
@@ -57,6 +57,9 @@ import {
   normalizeDefinitionIconName,
 } from "./definitionIcons";
 import { GlyphSvg } from "../icons/GlyphSvg";
+import { weekdayOf } from "../schedule/cycle";
+import { useAppTimezone } from "../time/AppTimezone";
+import { todayIn } from "../time/zone";
 import "./DefinitionsTab.css";
 
 /** ADMIN-SPEC §1: every scroll column ends with 92px so content clears the tab bar. */
@@ -121,20 +124,13 @@ type LoadState =
 /** `null` = closed, `"new"` = creating, a definition = editing it. */
 type SheetTarget = null | "new" | QuestDefinition;
 
-function pad2(n: number): string {
-  return String(n).padStart(2, "0");
-}
-
-function localIsoDate(date: Date): string {
-  return `${date.getFullYear()}-${pad2(date.getMonth() + 1)}-${pad2(date.getDate())}`;
-}
-
 function emptyDueTimes(): Record<WindowName, string> {
   return { morning: "", afternoon: "", evening: "" };
 }
 
-function newDraft(activeChildren: AdminChild[]): Draft {
-  const today = new Date();
+/** Draft defaults take `today` ("YYYY-MM-DD") in the application timezone. */
+function newDraft(activeChildren: AdminChild[], today: string): Draft {
+  const [, month, day] = today.split("-").map(Number);
   return {
     title: "",
     icon: null,
@@ -142,22 +138,22 @@ function newDraft(activeChildren: AdminChild[]): Draft {
     assigneeIds: activeChildren.length === 1 ? [activeChildren[0].id] : [],
     repeats: "daily",
     interval: "1",
-    weekdays: [(today.getDay() + 6) % 7],
-    dayOfMonth: String(today.getDate()),
-    month: String(today.getMonth() + 1),
+    weekdays: [weekdayOf(today)],
+    dayOfMonth: String(day),
+    month: String(month),
     monthlyWeekday: null,
     windows: [],
     dueTimes: emptyDueTimes(),
     // Mirrors the API's create default: no instance on an away day.
     skipOnAway: true,
-    startDate: localIsoDate(today),
+    startDate: today,
     endDate: null,
   };
 }
 
-function draftFrom(definition: QuestDefinition, activeChildren: AdminChild[]): Draft {
+function draftFrom(definition: QuestDefinition, activeChildren: AdminChild[], today: string): Draft {
   const { rule } = definition;
-  const today = new Date();
+  const [, month, day] = today.split("-").map(Number);
   const active = new Set(activeChildren.map((child) => child.id));
   const dueTimes = emptyDueTimes();
   for (const w of definition.windows) dueTimes[w.window] = w.due_time ?? "";
@@ -172,9 +168,9 @@ function draftFrom(definition: QuestDefinition, activeChildren: AdminChild[]): D
     weekdays:
       rule.rule_type === "weekly" || rule.rule_type === "custom_days"
         ? [...(rule.weekday_set ?? [])]
-        : [(today.getDay() + 6) % 7],
-    dayOfMonth: String(rule.day_of_month ?? today.getDate()),
-    month: String(rule.month ?? today.getMonth() + 1),
+        : [weekdayOf(today)],
+    dayOfMonth: String(rule.day_of_month ?? day),
+    month: String(rule.month ?? month),
     monthlyWeekday:
       rule.rule_type === "monthly_weekday"
         ? { nth: rule.nth_weekday ?? 1, weekday: rule.nth_weekday_weekday ?? 0 }
@@ -465,9 +461,11 @@ function EditSheet({
   onSaved: () => void;
   onDeleted: (result: DefinitionDeleteResult) => void;
 }) {
-  const [draft, setDraft] = useState<Draft>(() =>
-    target === "new" ? newDraft(activeChildren) : draftFrom(target, activeChildren),
-  );
+  const timeZone = useAppTimezone();
+  const [draft, setDraft] = useState<Draft>(() => {
+    const today = todayIn(timeZone);
+    return target === "new" ? newDraft(activeChildren, today) : draftFrom(target, activeChildren, today);
+  });
   // The active selection as loaded: while it is unchanged, the PATCH omits
   // assignee_child_ids, because the API replaces the whole set and inactive
   // children cannot be sent back.
diff --git a/admin/src/history/HistoryTab.test.tsx b/admin/src/history/HistoryTab.test.tsx
index 506bd08..5ab8aa0 100644
--- a/admin/src/history/HistoryTab.test.tsx
+++ b/admin/src/history/HistoryTab.test.tsx
@@ -5,6 +5,7 @@ import type { HistoryFilter, HistoryRow } from "../api/history";
 import { storeTokens } from "../auth/oidc";
 import { TransitionsProvider } from "../api/useTransitions";
 import { frame, testStream, type TestStream } from "../api/testStream";
+import { AppTimezoneProvider } from "../time/AppTimezone";
 
 const TODAY = "2026-09-23";
 
@@ -629,3 +630,114 @@ describe("HistoryTab live updates", () => {
     expect(screen.getAllByTestId("history-row")).toHaveLength(ROWS.all.length);
   });
 });
+
+describe("HistoryTab in the stored application timezone", () => {
+  // 13:00 UTC on Sep 23 is 01:00 on Sep 24 in Auckland (NZST, UTC+12).
+  const NOW = new Date("2026-09-23T13:00:00Z");
+  // Due 00:10 Auckland on Sep 24, done 00:30 Auckland (12:30 UTC on Sep 23).
+  const LATE_NZ = row({
+    instance_id: 7,
+    quest_title: "Feed cat",
+    due_date: "2026-09-24",
+    due_time: "00:10",
+    occurred_at: "2026-09-23T12:30:00Z",
+    was_on_time: false,
+  });
+  // 22:00 Auckland on Sep 23; 10:00 UTC.
+  const EVENING_NZ = row({ instance_id: 8, occurred_at: "2026-09-23T10:00:00Z" });
+
+  let fetchMock: ReturnType<typeof vi.fn>;
+
+  function historyRequests(): URL[] {
+    return fetchMock.mock.calls
+      .map(([url]) => new URL(String(url), "http://x"))
+      .filter((url) => url.pathname === "/api/v1/admin/history");
+  }
+
+  async function renderWithZone(timezone: string) {
+    fetchMock = vi.fn((url: string) => {
+      const parsed = new URL(url, "http://x");
+      if (parsed.pathname.endsWith("/api/v1/admin/settings")) {
+        return Promise.resolve(jsonResponse({ timezone }));
+      }
+      const filter = parsed.searchParams.get("filter");
+      const rows = filter === "all" ? [EVENING_NZ, LATE_NZ] : [];
+      return Promise.resolve(
+        jsonResponse({
+          filter,
+          start: parsed.searchParams.get("start"),
+          end: parsed.searchParams.get("end"),
+          count: rows.length,
+          rows,
+        }),
+      );
+    });
+    vi.stubGlobal("fetch", fetchMock);
+    render(
+      <AppTimezoneProvider>
+        <HistoryTab />
+      </AppTimezoneProvider>,
+    );
+    await screen.findByTestId("stat-on-time");
+  }
+
+  function times(section: HTMLElement): string[] {
+    return Array.from(section.querySelectorAll(".history-event-time")).map(
+      (el) => el.textContent ?? "",
+    );
+  }
+
+  beforeAll(() => {
+    vi.stubEnv("TZ", "UTC");
+  });
+
+  afterAll(() => {
+    vi.unstubAllEnvs();
+  });
+
+  beforeEach(() => {
+    sessionStorage.clear();
+    storeTokens({ access_token: "at-123", expires_in: 600 });
+    vi.useFakeTimers({ toFake: ["Date"], now: NOW });
+  });
+
+  afterEach(() => {
+    cleanup();
+    vi.useRealTimers();
+    vi.unstubAllGlobals();
+  });
+
+  it("today, day grouping, clock and lateness follow the stored zone", async () => {
+    await renderWithZone("Pacific/Auckland");
+
+    for (const url of historyRequests()) {
+      expect(url.searchParams.get("end")).toBe("2026-09-24");
+      expect(url.searchParams.get("start")).toBe("2026-09-11");
+    }
+    const today = screen.getByTestId("day-2026-09-24");
+    expect(within(today).getByText("Today")).toBeTruthy();
+    expect(times(today)).toEqual(["12:30 AM"]);
+    expect(metas(today)).toEqual(["completed · panel (Declan) · late 20 min"]);
+
+    const yesterday = screen.getByTestId("day-2026-09-23");
+    expect(within(yesterday).getByText("Yesterday")).toBeTruthy();
+    expect(times(yesterday)).toEqual(["10:00 PM"]);
+  });
+
+  it("an empty stored zone keeps the browser's local day and clock", async () => {
+    await renderWithZone("");
+
+    for (const url of historyRequests()) {
+      expect(url.searchParams.get("end")).toBe("2026-09-23");
+    }
+    expect(screen.queryByTestId("day-2026-09-24")).toBeNull();
+    const today = screen.getByTestId("day-2026-09-23");
+    expect(within(today).getByText("Today")).toBeTruthy();
+    expect(times(today)).toEqual(["12:30 PM", "10:00 AM"]);
+    // Due 00:10 UTC on Sep 24 is after the 12:30 UTC completion: no minutes.
+    expect(metas(today)).toEqual([
+      "completed · panel (Declan) · late",
+      "completed · panel (Declan) · on time",
+    ]);
+  });
+});
diff --git a/admin/src/history/HistoryTab.tsx b/admin/src/history/HistoryTab.tsx
index 33ab53d..098beba 100644
--- a/admin/src/history/HistoryTab.tsx
+++ b/admin/src/history/HistoryTab.tsx
@@ -9,9 +9,10 @@ import { ApiForbiddenError } from "../api/client";
 import type { TransitionEvent } from "../api/events";
 import { useTransitions } from "../api/useTransitions";
 import { exportHistoryCsv, fetchHistory, type HistoryFilter, type HistoryRow } from "../api/history";
-import { localTodayIso } from "../schedule/cycle";
 import { dayLabel, groupByDay, rowMeta, rowTime, shiftIso } from "./format";
 import { DownloadGlyph, LockGlyph } from "./glyphs";
+import { useAppTimezone } from "../time/AppTimezone";
+import { todayIn } from "../time/zone";
 import "./HistoryTab.css";
 
 /** ADMIN-SPEC §1: every scroll column ends with 92px so content clears the tab bar. */
@@ -129,7 +130,7 @@ function StatRow({ stats }: { stats: HistoryStats }) {
   );
 }
 
-function EventRow({ row }: { row: HistoryRow }) {
+function EventRow({ row, timeZone }: { row: HistoryRow; timeZone: string }) {
   return (
     <li className="history-event" data-testid="history-row">
       <span
@@ -142,10 +143,10 @@ function EventRow({ row }: { row: HistoryRow }) {
           {row.quest_title} · {row.child_name}
         </div>
         <div className="history-event-meta" data-testid="history-meta">
-          {rowMeta(row)}
+          {rowMeta(row, timeZone)}
         </div>
       </div>
-      <span className="history-event-time">{rowTime(row)}</span>
+      <span className="history-event-time">{rowTime(row, timeZone)}</span>
     </li>
   );
 }
@@ -161,7 +162,10 @@ function FooterNote() {
   );
 }
 
-export default function HistoryTab({ today = localTodayIso() }: { today?: string }) {
+/** `today` ("YYYY-MM-DD") defaults to today in the application timezone. */
+export default function HistoryTab({ today: todayProp }: { today?: string }) {
+  const timeZone = useAppTimezone();
+  const today = todayProp ?? todayIn(timeZone);
   const [filter, setFilter] = useState<HistoryFilter>("all");
   const [state, setState] = useState<LoadState>({ kind: "loading" });
   const [attempt, setAttempt] = useState(0);
@@ -244,7 +248,7 @@ export default function HistoryTab({ today = localTodayIso() }: { today?: string
       </div>
     );
   } else {
-    const groups = groupByDay(shown.data.rows);
+    const groups = groupByDay(shown.data.rows, timeZone);
     body =
       groups.length > 0 ? (
         groups.map((group) => (
@@ -252,7 +256,7 @@ export default function HistoryTab({ today = localTodayIso() }: { today?: string
             <h3 className="history-section-label">{dayLabel(group.day, today)}</h3>
             <ul className="history-card history-list">
               {group.rows.map((row, index) => (
-                <EventRow key={`${row.instance_id}-${row.event_type}-${row.occurred_at ?? ""}-${index}`} row={row} />
+                <EventRow key={`${row.instance_id}-${row.event_type}-${row.occurred_at ?? ""}-${index}`} row={row} timeZone={timeZone} />
               ))}
             </ul>
           </section>
diff --git a/admin/src/history/format.ts b/admin/src/history/format.ts
index 7575563..5b64058 100644
--- a/admin/src/history/format.ts
+++ b/admin/src/history/format.ts
@@ -4,12 +4,13 @@
  * Calendar dates ("YYYY-MM-DD") are handled by their components (never
  * `new Date("YYYY-MM-DD")`, which is UTC midnight and reads as the previous
  * day in negative-offset zones); event stamps are UTC and shown in the
- * viewer's local time.
+ * application timezone (`timeZone`: the stored IANA zone, "" = browser).
  */
 import type { HistoryRow } from "../api/history";
-import { dayNumber, isoFromDayNumber, localTodayIso } from "../schedule/cycle";
+import { dayNumber, isoFromDayNumber } from "../schedule/cycle";
 import { shortDate } from "../schedule/format";
 import { formatClockTime, formatDueTime } from "../today/format";
+import { isoDateIn, wallClockInstant } from "../time/zone";
 
 const MS_PER_MINUTE = 60_000;
 
@@ -19,25 +20,21 @@ export function shiftIso(iso: string, days: number): string {
 }
 
 /** The local calendar day an event belongs to (due_date for missed rows). */
-export function rowDay(row: HistoryRow): string {
-  return row.occurred_at ? localTodayIso(new Date(row.occurred_at)) : row.due_date;
+export function rowDay(row: HistoryRow, timeZone: string): string {
+  return row.occurred_at ? isoDateIn(new Date(row.occurred_at), timeZone) : row.due_date;
 }
 
-/** The row's due moment as local wall-clock time, or null without a due time. */
-function dueMoment(row: HistoryRow): Date | null {
+/** The row's due moment (epoch ms) as local wall-clock time, or null without a due time. */
+function dueMoment(row: HistoryRow, timeZone: string): number | null {
   const match = /^(\d{2}):(\d{2})/.exec(row.due_time ?? "");
   if (!match) return null;
-  const [year, month, day] = row.due_date.split("-").map(Number);
-  return new Date(year, month - 1, day, Number(match[1]), Number(match[2]));
+  return wallClockInstant(row.due_date, Number(match[1]), Number(match[2]), timeZone);
 }
 
 /** Newest first; a missed row sorts at its due moment (or the end of its day). */
-function sortKey(row: HistoryRow): number {
+function sortKey(row: HistoryRow, timeZone: string): number {
   if (row.occurred_at) return Date.parse(row.occurred_at);
-  const due = dueMoment(row);
-  if (due) return due.getTime();
-  const [year, month, day] = row.due_date.split("-").map(Number);
-  return new Date(year, month - 1, day, 23, 59).getTime();
+  return dueMoment(row, timeZone) ?? wallClockInstant(row.due_date, 23, 59, timeZone);
 }
 
 export interface DayGroup {
@@ -46,10 +43,10 @@ export interface DayGroup {
 }
 
 /** Rows grouped by day, newest day first and newest row first within a day. */
-export function groupByDay(rows: HistoryRow[]): DayGroup[] {
+export function groupByDay(rows: HistoryRow[], timeZone: string): DayGroup[] {
   const groups = new Map<string, HistoryRow[]>();
   for (const row of rows) {
-    const day = rowDay(row);
+    const day = rowDay(row, timeZone);
     groups.set(day, [...(groups.get(day) ?? []), row]);
   }
   return [...groups.entries()]
@@ -57,7 +54,7 @@ export function groupByDay(rows: HistoryRow[]): DayGroup[] {
     .map(([day, dayRows]) => ({
       day,
       // Stable sort: rows at the same moment keep the API's append order.
-      rows: [...dayRows].sort((a, b) => sortKey(b) - sortKey(a)),
+      rows: [...dayRows].sort((a, b) => sortKey(b, timeZone) - sortKey(a, timeZone)),
     }));
 }
 
@@ -72,23 +69,23 @@ export function dayLabel(day: string, today: string): string {
 }
 
 /** "on time", "late 22 min", or "late" when the lateness is not derivable. */
-function onTimeFlag(row: HistoryRow): string | null {
+function onTimeFlag(row: HistoryRow, timeZone: string): string | null {
   if (row.event_type !== "completed" || row.was_on_time === null) return null;
   if (row.was_on_time) return "on time";
-  const due = dueMoment(row);
-  if (!due || !row.occurred_at) return "late";
-  const minutes = Math.round((Date.parse(row.occurred_at) - due.getTime()) / MS_PER_MINUTE);
+  const due = dueMoment(row, timeZone);
+  if (due === null || !row.occurred_at) return "late";
+  const minutes = Math.round((Date.parse(row.occurred_at) - due) / MS_PER_MINUTE);
   return minutes > 0 ? `late ${minutes} min` : "late";
 }
 
 /** `<event type> · <actor>` plus the on-time flag for completions. */
-export function rowMeta(row: HistoryRow): string {
-  const flag = onTimeFlag(row);
+export function rowMeta(row: HistoryRow, timeZone: string): string {
+  const flag = onTimeFlag(row, timeZone);
   return [row.event_type, row.actor, flag].filter(Boolean).join(" · ");
 }
 
 /** The event's local clock time; a missed row shows its due time, if any. */
-export function rowTime(row: HistoryRow): string {
-  if (row.occurred_at) return formatClockTime(row.occurred_at);
+export function rowTime(row: HistoryRow, timeZone: string): string {
+  if (row.occurred_at) return formatClockTime(row.occurred_at, timeZone);
   return row.due_time ? formatDueTime(row.due_time) : "";
 }
diff --git a/admin/src/schedule/OverrideEditor.test.tsx b/admin/src/schedule/OverrideEditor.test.tsx
index c57c5d5..8e57c6c 100644
--- a/admin/src/schedule/OverrideEditor.test.tsx
+++ b/admin/src/schedule/OverrideEditor.test.tsx
@@ -74,6 +74,8 @@ async function routeFetch(url: string, init: RequestInit = {}): Promise<Response
     overrides = overrides.filter((o) => o.id !== Number(deleteMatch[1]));
     return jsonResponse({ status: "ok" });
   }
+  // The shell loads the stored application timezone first ("" = unset).
+  if (path.endsWith("/admin/settings")) return jsonResponse({ timezone: "" });
   if (path.endsWith("/admin/children")) return jsonResponse({ children: CHILDREN });
   const patternsMatch = /\/children\/(\d+)\/presence-patterns$/.exec(path);
   if (patternsMatch) {
diff --git a/admin/src/schedule/ScheduleTab.test.tsx b/admin/src/schedule/ScheduleTab.test.tsx
index 91b0e62..087c0b8 100644
--- a/admin/src/schedule/ScheduleTab.test.tsx
+++ b/admin/src/schedule/ScheduleTab.test.tsx
@@ -1,9 +1,10 @@
-import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { afterAll, afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
 import { cleanup, fireEvent, render, screen, waitFor, within } from "@testing-library/react";
 import ScheduleTab from "./ScheduleTab";
 import type { AdminChild } from "../api/definitions";
 import type { PresenceOverride, PresencePattern } from "../api/presence";
 import { storeTokens } from "../auth/oidc";
+import { AppTimezoneProvider } from "../time/AppTimezone";
 import { cycleWeekIndex, monthDates, weekdayOf } from "./cycle";
 
 function child(id: number, display_name: string, sort_order: number, is_active = true): AdminChild {
@@ -655,3 +656,55 @@ describe("ScheduleTab", () => {
     expect(await screen.findByTestId("pattern-1")).toBeTruthy();
   });
 });
+
+describe("ScheduleTab today in the stored application timezone", () => {
+  async function renderWithZone(timezone: string) {
+    fetchMock = vi.fn(async (url: string, init?: RequestInit) =>
+      String(url).endsWith("/api/v1/admin/settings")
+        ? jsonResponse({ timezone })
+        : routeFetch(url, init),
+    );
+    vi.stubGlobal("fetch", fetchMock);
+    render(
+      <AppTimezoneProvider>
+        <ScheduleTab />
+      </AppTimezoneProvider>,
+    );
+    await screen.findByTestId("pattern-1");
+  }
+
+  beforeAll(() => {
+    vi.stubEnv("TZ", "UTC");
+  });
+
+  afterAll(() => {
+    vi.unstubAllEnvs();
+  });
+
+  beforeEach(() => {
+    sessionStorage.clear();
+    storeTokens({ access_token: "at-123", expires_in: 600 });
+    patterns = { 1: [DECLAN_HOME], 2: [MAEVE_THU_FRI, MAEVE_WEEKENDS], 3: [] };
+    writeFailure = null;
+    // 13:00 UTC on Sep 23 is already 01:00 on Sep 24 in Auckland.
+    vi.useFakeTimers({ toFake: ["Date"], now: new Date("2026-09-23T13:00:00Z") });
+  });
+
+  afterEach(() => {
+    cleanup();
+    vi.useRealTimers();
+    vi.unstubAllGlobals();
+  });
+
+  it("marks today in the stored zone", async () => {
+    await renderWithZone("Pacific/Auckland");
+    expect(day("2026-09-24").className).toContain("schedule-day--today");
+    expect(day("2026-09-23").className).not.toContain("schedule-day--today");
+  });
+
+  it("an empty stored zone marks the browser's local today", async () => {
+    await renderWithZone("");
+    expect(day("2026-09-23").className).toContain("schedule-day--today");
+    expect(day("2026-09-24").className).not.toContain("schedule-day--today");
+  });
+});
diff --git a/admin/src/schedule/ScheduleTab.tsx b/admin/src/schedule/ScheduleTab.tsx
index 06074ac..16243f2 100644
--- a/admin/src/schedule/ScheduleTab.tsx
+++ b/admin/src/schedule/ScheduleTab.tsx
@@ -20,7 +20,6 @@ import {
 import {
   cycleLabel,
   dayState,
-  localTodayIso,
   monthDates,
   monthStart,
   patternDaysLabel,
@@ -38,6 +37,8 @@ import {
 } from "./glyphs";
 import OverrideEditor from "./OverrideEditor";
 import PatternEditor from "./PatternEditor";
+import { useAppTimezone } from "../time/AppTimezone";
+import { todayIn } from "../time/zone";
 import "./ScheduleTab.css";
 
 /** ADMIN-SPEC §1: every scroll column ends with 92px so content clears the tab bar. */
@@ -324,11 +325,13 @@ function OverrideRow({ override, childName, deletion, onAskDelete, onKeep, onDel
 }
 
 export interface ScheduleTabProps {
-  /** "YYYY-MM-DD"; defaults to the viewer's local date. */
+  /** "YYYY-MM-DD"; defaults to today in the application timezone. */
   today?: string;
 }
 
-export default function ScheduleTab({ today = localTodayIso() }: ScheduleTabProps) {
+export default function ScheduleTab({ today: todayProp }: ScheduleTabProps) {
+  const timeZone = useAppTimezone();
+  const today = todayProp ?? todayIn(timeZone);
   const [state, setState] = useState<LoadState>({ kind: "loading" });
   const [attempt, setAttempt] = useState(0);
   const [selectedId, setSelectedId] = useState<number | null>(null);
diff --git a/admin/src/schedule/cycle.ts b/admin/src/schedule/cycle.ts
index d8e3491..9701b88 100644
--- a/admin/src/schedule/cycle.ts
+++ b/admin/src/schedule/cycle.ts
@@ -55,13 +55,6 @@ export function cycleWeekIndex(anchorDate: string, date: string, cycleLengthWeek
   return mod(Math.floor(days / 7), cycleLengthWeeks);
 }
 
-/** The viewer's local calendar date. */
-export function localTodayIso(now: Date = new Date()): string {
-  const month = String(now.getMonth() + 1).padStart(2, "0");
-  const day = String(now.getDate()).padStart(2, "0");
-  return `${now.getFullYear()}-${month}-${day}`;
-}
-
 /** "YYYY-MM-01" of the month containing `iso`, shifted by `delta` months. */
 export function monthStart(iso: string, delta = 0): string {
   const [year, month] = iso.split("-").map(Number);
diff --git a/admin/src/settings/SettingsScreen.test.tsx b/admin/src/settings/SettingsScreen.test.tsx
index 3c4cfc2..3be1e5d 100644
--- a/admin/src/settings/SettingsScreen.test.tsx
+++ b/admin/src/settings/SettingsScreen.test.tsx
@@ -6,6 +6,7 @@ import SettingsScreen, { SCROLL_BOTTOM_PADDING } from "./SettingsScreen";
 import type { AdminChild } from "../api/definitions";
 import type { HouseholdSettings } from "../api/settings";
 import { storeTokens } from "../auth/oidc";
+import { AppTimezoneProvider, useAppTimezone } from "../time/AppTimezone";
 
 const CHILDREN_PATH = "/api/v1/admin/children";
 const REORDER_PATH = `${CHILDREN_PATH}/reorder`;
@@ -791,3 +792,42 @@ describe("SettingsScreen — manual timezone control", () => {
     }
   });
 });
+
+describe("SettingsScreen — the saved zone applies app-wide", () => {
+  function ZoneProbe() {
+    return <output data-testid="app-zone">{useAppTimezone() || "(browser)"}</output>;
+  }
+
+  beforeEach(() => {
+    sessionStorage.clear();
+    storeTokens({ access_token: "at-123", expires_in: 600 });
+    children = [child(1, "Declan", 1)];
+    settings = { ...DEFAULT_SETTINGS, timezone: "" };
+    writeResponse = null;
+    fetchMock = vi.fn(async (url: string, init?: RequestInit) => routeFetch(url, init));
+    vi.stubGlobal("fetch", fetchMock);
+  });
+
+  afterEach(() => {
+    cleanup();
+    vi.unstubAllGlobals();
+  });
+
+  it("a saved zone becomes the application timezone at once", async () => {
+    render(
+      <AppTimezoneProvider>
+        <ZoneProbe />
+        <SettingsScreen onClose={vi.fn()} />
+      </AppTimezoneProvider>,
+    );
+    const form = await screen.findByRole("form", { name: "Preferences" });
+    expect(screen.getByTestId("app-zone").textContent).toBe("(browser)");
+
+    fireEvent.change(within(form).getByRole("combobox", { name: "Timezone" }), {
+      target: { value: "America/New_York" },
+    });
+    fireEvent.click(within(form).getByRole("button", { name: "Save preferences" }));
+    await screen.findByText("Preferences saved.");
+    expect(screen.getByTestId("app-zone").textContent).toBe("America/New_York");
+  });
+});
diff --git a/admin/src/settings/SettingsScreen.tsx b/admin/src/settings/SettingsScreen.tsx
index 1f31baa..6a176ee 100644
--- a/admin/src/settings/SettingsScreen.tsx
+++ b/admin/src/settings/SettingsScreen.tsx
@@ -7,7 +7,8 @@
  * Preferences: the household settings (planning horizon, day rollover,
  * timezone, notifications). Save patches only the changed fields. The
  * timezone — the application's source of local time — is only ever set by
- * the admin picking or typing a zone here and saving it.
+ * the admin picking or typing a zone here and saving it; every zone loaded
+ * or saved here is published app-wide (time/AppTimezone.tsx).
  *
  * One write at a time across both sections.
  */
@@ -35,6 +36,7 @@ import {
   type SettingsChanges,
 } from "../api/settings";
 import { FOCUSABLE, inertOutside } from "../schedule/OverrideEditor";
+import { usePublishAppTimezone } from "../time/AppTimezone";
 import { ArrowDownGlyph, ArrowUpGlyph, ChevronLeftGlyph, PlusGlyph } from "./glyphs";
 import "./SettingsScreen.css";
 
@@ -593,6 +595,7 @@ export default function SettingsScreen({ onClose }: { onClose: () => void }) {
   const titleRef = useRef<HTMLHeadingElement>(null);
   const addRef = useRef<HTMLButtonElement>(null);
   const formWasOpen = useRef(false);
+  const publishTimezone = usePublishAppTimezone();
 
   // Modal focus: move in on open, keep the background out of reach, and hand
   // focus back to the opener (the Settings button) on close.
@@ -634,7 +637,9 @@ export default function SettingsScreen({ onClose }: { onClose: () => void }) {
     setPreferences({ kind: "loading" });
     fetchSettings()
       .then((settings) => {
-        if (!cancelled) setPreferences({ kind: "ready", settings });
+        if (cancelled) return;
+        setPreferences({ kind: "ready", settings });
+        publishTimezone(settings.timezone);
       })
       .catch((error: unknown) => {
         if (cancelled) return;
@@ -728,6 +733,7 @@ export default function SettingsScreen({ onClose }: { onClose: () => void }) {
     try {
       const settings = await updateSettings(changes);
       setPreferences({ kind: "ready", settings });
+      publishTimezone(settings.timezone);
       setPreferencesMessage({ kind: "info", text: "Preferences saved." });
     } catch (error) {
       setPreferencesMessage({
diff --git a/admin/src/time/AppTimezone.tsx b/admin/src/time/AppTimezone.tsx
new file mode 100644
index 0000000..b31a440
--- /dev/null
+++ b/admin/src/time/AppTimezone.tsx
@@ -0,0 +1,91 @@
+/**
+ * The stored application timezone, loaded once per signed-in shell.
+ *
+ * <AppTimezoneProvider> fetches the household settings and renders its
+ * screens only once the zone is known (a failed load says so and offers a
+ * retry), so no screen ever computes local time in a zone it will not keep.
+ * The Settings screen publishes every zone it loads or saves, so a change
+ * applies app-wide at once.
+ *
+ * Without a provider (a screen rendered on its own, e.g. in a test)
+ * useAppTimezone() is "" — the documented unset value, i.e. browser-local.
+ */
+import { createContext, useContext, useEffect, useState, type ReactNode } from "react";
+import { ApiForbiddenError } from "../api/client";
+import { fetchSettings } from "../api/settings";
+
+interface ZoneHub {
+  timeZone: string;
+  publish(timeZone: string): void;
+}
+
+const AppTimezoneContext = createContext<ZoneHub | null>(null);
+
+type LoadState =
+  | { kind: "loading" }
+  | { kind: "error"; message: string }
+  | { kind: "ready"; timeZone: string };
+
+export function AppTimezoneProvider({ children }: { children: ReactNode }) {
+  const [state, setState] = useState<LoadState>({ kind: "loading" });
+  const [attempt, setAttempt] = useState(0);
+
+  useEffect(() => {
+    let cancelled = false;
+    setState({ kind: "loading" });
+    fetchSettings()
+      .then((settings) => {
+        if (!cancelled) setState({ kind: "ready", timeZone: settings.timezone });
+      })
+      .catch((error: unknown) => {
+        if (cancelled) return;
+        setState({
+          kind: "error",
+          message:
+            error instanceof ApiForbiddenError
+              ? error.message
+              : "The application timezone could not be loaded. Check your connection and try again.",
+        });
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, [attempt]);
+
+  if (state.kind === "loading") {
+    return (
+      <div className="admin-loading" role="status" data-testid="timezone-loading">
+        Loading…
+      </div>
+    );
+  }
+  if (state.kind === "error") {
+    return (
+      <div className="admin-error" role="alert" data-testid="timezone-error">
+        <p>{state.message}</p>
+        <button type="button" onClick={() => setAttempt((n) => n + 1)}>
+          Try again
+        </button>
+      </div>
+    );
+  }
+  const hub: ZoneHub = {
+    timeZone: state.timeZone,
+    publish: (timeZone) =>
+      setState((prev) =>
+        prev.kind === "ready" && prev.timeZone === timeZone ? prev : { kind: "ready", timeZone },
+      ),
+  };
+  return <AppTimezoneContext.Provider value={hub}>{children}</AppTimezoneContext.Provider>;
+}
+
+/** The stored application timezone: an IANA name, or "" (browser-local). */
+export function useAppTimezone(): string {
+  return useContext(AppTimezoneContext)?.timeZone ?? "";
+}
+
+/** Publish a zone just loaded or saved; a no-op without a provider. */
+export function usePublishAppTimezone(): (timeZone: string) => void {
+  const hub = useContext(AppTimezoneContext);
+  return (timeZone) => hub?.publish(timeZone);
+}
diff --git a/admin/src/time/zone.test.ts b/admin/src/time/zone.test.ts
new file mode 100644
index 0000000..03c3511
--- /dev/null
+++ b/admin/src/time/zone.test.ts
@@ -0,0 +1,60 @@
+import { afterAll, beforeAll, describe, expect, it, vi } from "vitest";
+import { isoDateIn, todayIn, wallClockInstant, zoneOption } from "./zone";
+import { formatClockTime } from "../today/format";
+
+// 13:00 UTC on Sep 23 is already 01:00 on Sep 24 in Auckland (NZST, UTC+12).
+const NOW = new Date("2026-09-23T13:00:00Z");
+
+describe("application timezone helpers (process in UTC)", () => {
+  beforeAll(() => {
+    vi.stubEnv("TZ", "UTC");
+  });
+
+  afterAll(() => {
+    vi.unstubAllEnvs();
+  });
+
+  it("a stored zone decides the calendar date; empty means the browser's zone", () => {
+    expect(todayIn("Pacific/Auckland", NOW)).toBe("2026-09-24");
+    expect(isoDateIn(NOW, "Pacific/Auckland")).toBe("2026-09-24");
+    expect(todayIn("", NOW)).toBe("2026-09-23");
+  });
+
+  it("wall-clock time converts in the stored zone, across its DST change", () => {
+    // NZST (UTC+12) before 27 Sep 2026, NZDT (UTC+13) after.
+    expect(wallClockInstant("2026-09-24", 0, 10, "Pacific/Auckland")).toBe(
+      Date.parse("2026-09-23T12:10:00Z"),
+    );
+    expect(wallClockInstant("2026-09-28", 7, 30, "Pacific/Auckland")).toBe(
+      Date.parse("2026-09-27T18:30:00Z"),
+    );
+    expect(wallClockInstant("2026-09-24", 0, 10, "")).toBe(Date.parse("2026-09-24T00:10:00Z"));
+  });
+
+  it("the completion clock reads in the stored zone", () => {
+    expect(formatClockTime("2026-09-23T11:04:00Z", "Pacific/Auckland")).toBe("11:04 PM");
+    expect(formatClockTime("2026-09-23T11:04:00Z", "")).toBe("11:04 AM");
+  });
+
+  it("an invalid stored zone fails fast", () => {
+    expect(zoneOption("")).toBeUndefined();
+    expect(() => todayIn("Not/AZone", NOW)).toThrow(RangeError);
+  });
+});
+
+describe("empty zone keeps browser-local behavior", () => {
+  beforeAll(() => {
+    vi.stubEnv("TZ", "America/Los_Angeles");
+  });
+
+  afterAll(() => {
+    vi.unstubAllEnvs();
+  });
+
+  it("matches the browser's own calendar and wall clock", () => {
+    // 13:00 UTC is 06:00 PDT on Sep 23.
+    expect(todayIn("", NOW)).toBe("2026-09-23");
+    expect(wallClockInstant("2026-09-23", 7, 30, "")).toBe(new Date(2026, 8, 23, 7, 30).getTime());
+    expect(formatClockTime("2026-09-23T14:04:00Z", "")).toBe("7:04 AM");
+  });
+});
diff --git a/admin/src/time/zone.ts b/admin/src/time/zone.ts
new file mode 100644
index 0000000..ea8b1de
--- /dev/null
+++ b/admin/src/time/zone.ts
@@ -0,0 +1,79 @@
+/**
+ * Local time in the application timezone.
+ *
+ * The admin-saved zone (settings `timezone`, an IANA name) is the single
+ * source of local-time truth for the whole application. "" means no zone is
+ * stored, and only then does the browser's own zone apply. Every helper takes
+ * that stored value as-is; an invalid zone name throws (Intl's RangeError).
+ */
+
+/** The `timeZone` option for Intl: the stored zone, or undefined (browser) for "". */
+export function zoneOption(timeZone: string): string | undefined {
+  return timeZone === "" ? undefined : timeZone;
+}
+
+interface WallClock {
+  year: number;
+  month: number;
+  day: number;
+  hour: number;
+  minute: number;
+  second: number;
+}
+
+function wallClock(instant: number, timeZone: string): WallClock {
+  const parts = new Intl.DateTimeFormat("en-US", {
+    timeZone: zoneOption(timeZone),
+    hourCycle: "h23",
+    year: "numeric",
+    month: "2-digit",
+    day: "2-digit",
+    hour: "2-digit",
+    minute: "2-digit",
+    second: "2-digit",
+  }).formatToParts(instant);
+  const part = (type: Intl.DateTimeFormatPartTypes) =>
+    Number(parts.find((p) => p.type === type)?.value);
+  return {
+    year: part("year"),
+    month: part("month"),
+    day: part("day"),
+    hour: part("hour"),
+    minute: part("minute"),
+    second: part("second"),
+  };
+}
+
+/** The "YYYY-MM-DD" calendar date of `instant` in the zone. */
+export function isoDateIn(instant: Date, timeZone: string): string {
+  const { year, month, day } = wallClock(instant.getTime(), timeZone);
+  return `${year}-${String(month).padStart(2, "0")}-${String(day).padStart(2, "0")}`;
+}
+
+/** Today's calendar date in the zone. */
+export function todayIn(timeZone: string, now: Date = new Date()): string {
+  return isoDateIn(now, timeZone);
+}
+
+/** The zone's UTC offset in ms at `instant` (wall clock minus UTC). */
+function offsetAt(instant: number, timeZone: string): number {
+  const c = wallClock(instant, timeZone);
+  const wholeSeconds = Math.floor(instant / 1000) * 1000;
+  return Date.UTC(c.year, c.month - 1, c.day, c.hour, c.minute, c.second) - wholeSeconds;
+}
+
+/**
+ * Epoch ms at which the zone's wall clock reads `hour:minute` on the
+ * "YYYY-MM-DD" date. Two passes settle the offset across a DST change.
+ */
+export function wallClockInstant(
+  iso: string,
+  hour: number,
+  minute: number,
+  timeZone: string,
+): number {
+  const [year, month, day] = iso.split("-").map(Number);
+  const asUtc = Date.UTC(year, month - 1, day, hour, minute);
+  const guess = asUtc - offsetAt(asUtc, timeZone);
+  return asUtc - offsetAt(guess, timeZone);
+}
diff --git a/admin/src/today/TodayTab.test.tsx b/admin/src/today/TodayTab.test.tsx
index 41a59b7..9fd54c9 100644
--- a/admin/src/today/TodayTab.test.tsx
+++ b/admin/src/today/TodayTab.test.tsx
@@ -5,6 +5,7 @@ import type { AdminSnapshot, SnapshotInstance } from "../api/snapshot";
 import { TransitionsProvider } from "../api/useTransitions";
 import { frame, testStream, type TestStream } from "../api/testStream";
 import { storeTokens } from "../auth/oidc";
+import { AppTimezoneProvider } from "../time/AppTimezone";
 
 function instance(overrides: Partial<SnapshotInstance>): SnapshotInstance {
   return {
@@ -406,3 +407,56 @@ describe("TodayTab Undo and live updates", () => {
     await waitFor(() => expect(streams[0].cancelled()).toBe(true));
   });
 });
+
+describe("TodayTab in the stored application timezone", () => {
+  function renderWithZone(timezone: string) {
+    fetchMock.mockImplementation((url: string) =>
+      Promise.resolve(
+        String(url).endsWith("/api/v1/admin/settings")
+          ? jsonResponse({ timezone })
+          : jsonResponse(SNAPSHOT),
+      ),
+    );
+    render(
+      <AppTimezoneProvider>
+        <TodayTab />
+      </AppTimezoneProvider>,
+    );
+  }
+
+  beforeAll(() => {
+    // The browser runs in UTC; the household lives in Auckland (UTC+12 on Sep 23).
+    vi.stubEnv("TZ", "UTC");
+  });
+
+  afterAll(() => {
+    vi.unstubAllEnvs();
+  });
+
+  beforeEach(() => {
+    sessionStorage.clear();
+    storeTokens({ access_token: "at-123", expires_in: 600 });
+    fetchMock = vi.fn();
+    vi.stubGlobal("fetch", fetchMock);
+  });
+
+  afterEach(() => {
+    cleanup();
+    vi.unstubAllGlobals();
+  });
+
+  it("shows the completion clock in the stored zone, not the browser's", async () => {
+    renderWithZone("Pacific/Auckland");
+    const completed = await screen.findByTestId("attention-12");
+    // 11:04 UTC is 11:04 PM in Auckland.
+    expect(within(completed).getByText("Completed 11:04 PM")).toBeTruthy();
+    // The header's day is the API's household-local today_iso, as-is.
+    expect(screen.getByText("Wednesday, September 23 · cycle day 5 of 14")).toBeTruthy();
+  });
+
+  it("an empty stored zone keeps the browser's local clock", async () => {
+    renderWithZone("");
+    const completed = await screen.findByTestId("attention-12");
+    expect(within(completed).getByText("Completed 11:04 AM")).toBeTruthy();
+  });
+});
diff --git a/admin/src/today/TodayTab.tsx b/admin/src/today/TodayTab.tsx
index 7646b87..a9519ec 100644
--- a/admin/src/today/TodayTab.tsx
+++ b/admin/src/today/TodayTab.tsx
@@ -13,6 +13,7 @@ import { ApiRequestError } from "../api/definitions";
 import { uncompleteInstance } from "../api/instances";
 import { useTransitions } from "../api/useTransitions";
 import SettingsScreen from "../settings/SettingsScreen";
+import { useAppTimezone } from "../time/AppTimezone";
 import {
   formatClockTime,
   formatDueTime,
@@ -165,6 +166,7 @@ function AttentionRow({ item, undo }: { item: AttentionItem; undo: UndoControl }
   const { instance, childName } = item;
   const overdue = isOverdueOpen(instance);
   const undoing = undo.pendingId === instance.id;
+  const timeZone = useAppTimezone();
   // TODO(e57facc2): wire "Mark done". The admin plane has no complete route
   // yet, so that action is inert here.
   return (
@@ -187,7 +189,7 @@ function AttentionRow({ item, undo }: { item: AttentionItem; undo: UndoControl }
         ) : (
           // The snapshot carries no completion actor, so "from panel" is not printed.
           <div className="today-event-meta">
-            Completed {formatClockTime(instance.completed_at as string)}
+            Completed {formatClockTime(instance.completed_at as string, timeZone)}
           </div>
         )}
       </div>
diff --git a/admin/src/today/format.ts b/admin/src/today/format.ts
index 80537c0..bfbfe97 100644
--- a/admin/src/today/format.ts
+++ b/admin/src/today/format.ts
@@ -4,8 +4,10 @@
  * Calendar dates ("YYYY-MM-DD") are parsed by their components and formatted
  * in UTC, so the printed day never shifts with the viewer's offset — unlike
  * `new Date("YYYY-MM-DD")`, which is UTC midnight and reads as the previous
- * day in negative-offset zones.
+ * day in negative-offset zones. Instants are shown in the application
+ * timezone (time/zone.ts).
  */
+import { zoneOption } from "../time/zone";
 
 const LOCALE = "en-US";
 
@@ -44,7 +46,11 @@ export function formatDueTime(hhmm: string): string {
   return format(date, { hour: "numeric", minute: "2-digit", timeZone: "UTC" });
 }
 
-/** A UTC ISO timestamp shown as the viewer's local time, "7:04 AM". */
-export function formatClockTime(isoTimestamp: string): string {
-  return format(new Date(isoTimestamp), { hour: "numeric", minute: "2-digit" });
+/** A UTC ISO timestamp shown as wall-clock time in `timeZone` ("" = browser), "7:04 AM". */
+export function formatClockTime(isoTimestamp: string, timeZone: string): string {
+  return format(new Date(isoTimestamp), {
+    hour: "numeric",
+    minute: "2-digit",
+    timeZone: zoneOption(timeZone),
+  });
 }
diff --git a/api/routes_panel.py b/api/routes_panel.py
index eb84e4d..54dde57 100644
--- a/api/routes_panel.py
+++ b/api/routes_panel.py
@@ -21,6 +21,7 @@ panel payload), and returns the documented JSON shape:
     {
       "today_iso": "2026-09-22",
       "cycle_day": 2,
+      "timezone": "Pacific/Auckland",
       "children": [
         {
           "child_id": 1,
@@ -45,7 +46,9 @@ panel payload), and returns the documented JSON shape:
 active children ``ORDER BY sort_order, id``); ``state`` is the
 documented panel spelling ``open`` | ``completed`` (§1 of
 design/ENTITIES-AND-SERVICES.md); ``cycle_day`` is today's 1-based day
-in the first scheduled child's custody cycle (0 when no child has one).
+in the first scheduled child's custody cycle (0 when no child has one);
+``timezone`` is the application timezone the admin stored (``""`` when
+unset), which the panel cards format their visible date and clock in.
 The same :class:`PanelSnapshotResponse` Pydantic model is the route's
 ``response_model``, so the OpenAPI document carries the shape too.
 """
@@ -126,12 +129,14 @@ class PanelSnapshotResponse(BaseModel):
 
     ``today_iso`` anchors the payload's day; ``cycle_day`` is today's
     1-based day in the first scheduled child's custody cycle (0 when no
-    child has a schedule); ``children`` is in the household's sort
-    order.
+    child has a schedule); ``timezone`` is the stored application
+    timezone (``""`` when unset); ``children`` is in the household's
+    sort order.
     """
 
     today_iso: str
     cycle_day: int
+    timezone: str
     children: list[PanelChildPayload]
 
 
@@ -218,6 +223,7 @@ async def panel_snapshot(request: Request) -> PanelSnapshotResponse:
     return PanelSnapshotResponse(
         today_iso=snapshot.today_iso,
         cycle_day=snapshot.cycle_day,
+        timezone=snapshot.timezone,
         children=[
             PanelChildPayload(
                 child_id=child.child_id,
diff --git a/custom_components/nestquest/coordinator.py b/custom_components/nestquest/coordinator.py
index 22cbb24..1f26b27 100644
--- a/custom_components/nestquest/coordinator.py
+++ b/custom_components/nestquest/coordinator.py
@@ -111,6 +111,8 @@ def snapshot_from_api_payload(payload: dict[str, Any]) -> NestQuestSnapshot:
       through verbatim;
     - ``present`` and ``next_present`` pass through verbatim (the API
       resolved them through the same presence engine server-side);
+    - ``timezone`` (the stored application timezone, ``""`` when unset)
+      passes through verbatim for the cards' date and clock;
     - the instance list is rebuilt IN ORDER, so the panel payload the
       sensors emit matches the route's order byte for byte.
 
@@ -161,6 +163,7 @@ def snapshot_from_api_payload(payload: dict[str, Any]) -> NestQuestSnapshot:
         today_iso=payload["today_iso"],
         children=tuple(children),
         cycle_day=payload["cycle_day"],
+        timezone=payload["timezone"],
     )
 
 
diff --git a/custom_components/nestquest/core/snapshot.py b/custom_components/nestquest/core/snapshot.py
index 88679be..5e438ee 100644
--- a/custom_components/nestquest/core/snapshot.py
+++ b/custom_components/nestquest/core/snapshot.py
@@ -96,6 +96,10 @@ class NestQuestSnapshot:
     today_iso: str
     children: tuple[ChildDaySnapshot, ...]
     cycle_day: int
+    #: The application timezone the admin stored (``""`` when unset —
+    #: the host's local time).  The panel cards format their visible
+    #: date and clock in it; it never re-resolves the day itself.
+    timezone: str = ""
 
 
 def _cycle_day(
@@ -319,4 +323,5 @@ async def build_snapshot(
         today_iso=today_iso,
         children=tuple(snapshots),
         cycle_day=_cycle_day(patterns, children, today),
+        timezone=settings.timezone,
     )
diff --git a/custom_components/nestquest/sensor.py b/custom_components/nestquest/sensor.py
index 7bfdfc1..2475dda 100644
--- a/custom_components/nestquest/sensor.py
+++ b/custom_components/nestquest/sensor.py
@@ -441,6 +441,9 @@ class NestQuestHouseholdDueTodaySensor(_NestQuestHouseholdSensor):
                 for child in data.children
             },
             "child_roster": _child_roster(data.children),
+            # The stored application timezone ("" when unset): the
+            # panel cards format their visible date and clock in it.
+            "timezone": data.timezone,
         }
 
 
diff --git a/custom_components/nestquest/www/nestquest-cards.js b/custom_components/nestquest/www/nestquest-cards.js
index a819a0b..594df65 100644
--- a/custom_components/nestquest/www/nestquest-cards.js
+++ b/custom_components/nestquest/www/nestquest-cards.js
@@ -65,7 +65,7 @@ const { is: nt, defineProperty: it, getOwnPropertyDescriptor: st, getOwnProperty
   return t;
 } }, Ze = (i, e) => !nt(i, e), ye = { attribute: !0, type: String, converter: ae, reflect: !1, useDefault: !1, hasChanged: Ze };
 Symbol.metadata ??= /* @__PURE__ */ Symbol("metadata"), K.litPropertyMetadata ??= /* @__PURE__ */ new WeakMap();
-let T = class extends HTMLElement {
+let z = class extends HTMLElement {
   static addInitializer(e) {
     this._$Ei(), (this.l ??= []).push(e);
   }
@@ -246,7 +246,7 @@ let T = class extends HTMLElement {
   firstUpdated(e) {
   }
 };
-T.elementStyles = [], T.shadowRootOptions = { mode: "open" }, T[I("elementProperties")] = /* @__PURE__ */ new Map(), T[I("finalized")] = /* @__PURE__ */ new Map(), ct?.({ ReactiveElement: T }), (K.reactiveElementVersions ??= []).push("2.1.2");
+z.elementStyles = [], z.shadowRootOptions = { mode: "open" }, z[I("elementProperties")] = /* @__PURE__ */ new Map(), z[I("finalized")] = /* @__PURE__ */ new Map(), ct?.({ ReactiveElement: z }), (K.reactiveElementVersions ??= []).push("2.1.2");
 const pe = globalThis, be = (i) => i, V = pe.trustedTypes, ve = V ? V.createPolicy("lit-html", { createHTML: (i) => i }) : void 0, Qe = "$lit$", k = `lit$${Math.random().toFixed(9).slice(2)}$`, We = "?" + k, dt = `<${We}>`, A = document, P = () => A.createComment(""), H = (i) => i === null || typeof i != "object" && typeof i != "function", he = Array.isArray, pt = (i) => he(i) || typeof i?.[Symbol.iterator] == "function", Y = `[ 	
 \f\r]`, L = /<(?:(!--|\/[^a-zA-Z])|(\/?[a-zA-Z][^>\s]*)|(\/?$))/g, xe = /-->/g, we = />/g, $ = RegExp(`>|${Y}(?:([^\\s"'>=/]+)(${Y}*=${Y}*(?:[^ 	
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@@ -303,11 +303,11 @@ class R {
     return n.innerHTML = e, n;
   }
 }
-function z(i, e, t = i, n) {
+function T(i, e, t = i, n) {
   if (e === S) return e;
   let s = n !== void 0 ? t._$Co?.[n] : t._$Cl;
   const a = H(e) ? void 0 : e._$litDirective$;
-  return s?.constructor !== a && (s?._$AO?.(!1), a === void 0 ? s = void 0 : (s = new a(i), s._$AT(i, t, n)), n !== void 0 ? (t._$Co ??= [])[n] = s : t._$Cl = s), s !== void 0 && (e = z(i, s._$AS(i, e.values), s, n)), e;
+  return s?.constructor !== a && (s?._$AO?.(!1), a === void 0 ? s = void 0 : (s = new a(i), s._$AT(i, t, n)), n !== void 0 ? (t._$Co ??= [])[n] = s : t._$Cl = s), s !== void 0 && (e = T(i, s._$AS(i, e.values), s, n)), e;
 }
 class ut {
   constructor(e, t) {
@@ -356,7 +356,7 @@ class N {
     return this._$AB;
   }
   _$AI(e, t = this) {
-    e = z(this, e, t), H(e) ? e === g || e == null || e === "" ? (this._$AH !== g && this._$AR(), this._$AH = g) : e !== this._$AH && e !== S && this._(e) : e._$litType$ !== void 0 ? this.$(e) : e.nodeType !== void 0 ? this.T(e) : pt(e) ? this.k(e) : this._(e);
+    e = T(this, e, t), H(e) ? e === g || e == null || e === "" ? (this._$AH !== g && this._$AR(), this._$AH = g) : e !== this._$AH && e !== S && this._(e) : e._$litType$ !== void 0 ? this.$(e) : e.nodeType !== void 0 ? this.T(e) : pt(e) ? this.k(e) : this._(e);
   }
   O(e) {
     return this._$AA.parentNode.insertBefore(e, this._$AB);
@@ -409,11 +409,11 @@ class J {
   _$AI(e, t = this, n, s) {
     const a = this.strings;
     let r = !1;
-    if (a === void 0) e = z(this, e, t, 0), r = !H(e) || e !== this._$AH && e !== S, r && (this._$AH = e);
+    if (a === void 0) e = T(this, e, t, 0), r = !H(e) || e !== this._$AH && e !== S, r && (this._$AH = e);
     else {
       const l = e;
       let o, p;
-      for (e = a[0], o = 0; o < a.length - 1; o++) p = z(this, l[n + o], t, o), p === S && (p = this._$AH[o]), r ||= !H(p) || p !== this._$AH[o], p === g ? e = g : e !== g && (e += (p ?? "") + a[o + 1]), this._$AH[o] = p;
+      for (e = a[0], o = 0; o < a.length - 1; o++) p = T(this, l[n + o], t, o), p === S && (p = this._$AH[o]), r ||= !H(p) || p !== this._$AH[o], p === g ? e = g : e !== g && (e += (p ?? "") + a[o + 1]), this._$AH[o] = p;
     }
     r && !s && this.j(e);
   }
@@ -442,7 +442,7 @@ class gt extends J {
     super(e, t, n, s, a), this.type = 5;
   }
   _$AI(e, t = this) {
-    if ((e = z(this, e, t, 0) ?? g) === S) return;
+    if ((e = T(this, e, t, 0) ?? g) === S) return;
     const n = this._$AH, s = e === g && n !== g || e.capture !== n.capture || e.once !== n.once || e.passive !== n.passive, a = e !== g && (n === g || s);
     s && this.element.removeEventListener(this.name, this, n), a && this.element.addEventListener(this.name, this, e), this._$AH = e;
   }
@@ -458,7 +458,7 @@ class _t {
     return this._$AM._$AU;
   }
   _$AI(e) {
-    z(this, e);
+    T(this, e);
   }
 }
 const yt = { I: N }, bt = pe.litHtmlPolyfillSupport;
@@ -473,7 +473,7 @@ const vt = (i, e, t) => {
   return s._$AI(i), s;
 };
 const ue = globalThis;
-let C = class extends T {
+let C = class extends z {
   constructor() {
     super(...arguments), this.renderOptions = { host: this }, this._$Do = void 0;
   }
@@ -592,7 +592,7 @@ function Ct(i) {
 function Se(i) {
   return Number.isFinite(i) ? Math.min(100, Math.max(0, i)) : 0;
 }
-function Te(i) {
+function ze(i) {
   return Math.max(0, Math.round(i));
 }
 function At(i) {
@@ -620,7 +620,7 @@ function St(i, e) {
   );
   return Number.isFinite(s) ? s - i : 0;
 }
-function Tt(i, e) {
+function zt(i, e) {
   if (typeof i != "string")
     return null;
   const t = i.split("-");
@@ -636,14 +636,14 @@ function Tt(i, e) {
   const r = Date.UTC(n, s - 1, a), l = new Date(r - St(r, e));
   return Number.isNaN(l.getTime()) ? null : l;
 }
-function zt(i) {
+function Tt(i) {
   const e = qt[i];
   return e || i.charAt(0).toUpperCase() + i.slice(1);
 }
 function Et(i, e) {
   return Mt[i] ?? e;
 }
-const ze = "polygon(0 0, 100% 0, 100% 62%, 50% 100%, 0 62%)", Ee = "M50 3 44.5 24.1 50 26 55.5 24.1Z M100 50 75.9 44.5 74 50 75.9 55.5Z M50 97 55.5 75.9 50 74 44.5 75.9Z M0 50 24.1 55.5 26 50 24.1 44.5Z M29.1 29.1 29.7 36.3 36.3 29.7Z M70.9 29.1 63.7 29.7 70.3 36.3Z M70.9 70.9 70.3 63.7 63.7 70.3Z M29.1 70.9 36.3 70.3 29.7 63.7Z", Nt = "M50 26.5 70.4 38.2 70.4 61.8 50 73.5 29.6 61.8 29.6 38.2Z", Lt = "M29.6 38.2H70.4M29.6 61.8H70.4M50 26.5 36.5 38.2M50 26.5 63.5 38.2M50 73.5 36.5 61.8M50 73.5 63.5 61.8M36.5 38.2V61.8M63.5 38.2V61.8M29.6 38.2 36.5 61.8M36.5 38.2 29.6 61.8M70.4 38.2 63.5 61.8M63.5 38.2 70.4 61.8", Ot = d`<svg
+const Te = "polygon(0 0, 100% 0, 100% 62%, 50% 100%, 0 62%)", Ee = "M50 3 44.5 24.1 50 26 55.5 24.1Z M100 50 75.9 44.5 74 50 75.9 55.5Z M50 97 55.5 75.9 50 74 44.5 75.9Z M0 50 24.1 55.5 26 50 24.1 44.5Z M29.1 29.1 29.7 36.3 36.3 29.7Z M70.9 29.1 63.7 29.7 70.3 36.3Z M70.9 70.9 70.3 63.7 63.7 70.3Z M29.1 70.9 36.3 70.3 29.7 63.7Z", Nt = "M50 26.5 70.4 38.2 70.4 61.8 50 73.5 29.6 61.8 29.6 38.2Z", Lt = "M29.6 38.2H70.4M29.6 61.8H70.4M50 26.5 36.5 38.2M50 26.5 63.5 38.2M50 73.5 36.5 61.8M50 73.5 63.5 61.8M36.5 38.2V61.8M63.5 38.2V61.8M29.6 38.2 36.5 61.8M36.5 38.2 29.6 61.8M70.4 38.2 63.5 61.8M63.5 38.2 70.4 61.8", Ot = d`<svg
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@@ -850,7 +850,7 @@ const ze = "polygon(0 0, 100% 0, 100% 62%, 50% 100%, 0 62%)", Ee = "M50 3 44.5 2
     width: 188px;
     height: 214px;
     padding: 4px;
-    clip-path: ${x(ze)};
+    clip-path: ${x(Te)};
     background: rgba(255, 255, 255, 0.22);
   }
 
@@ -861,7 +861,7 @@ const ze = "polygon(0 0, 100% 0, 100% 62%, 50% 100%, 0 62%)", Ee = "M50 3 44.5 2
     align-items: center;
     justify-content: center;
     padding-bottom: 70px;
-    clip-path: ${x(ze)};
+    clip-path: ${x(Te)};
     background: var(--nq-p-crest);
   }
 
@@ -1243,8 +1243,13 @@ const ze = "polygon(0 0, 100% 0, 100% 62%, 50% 100%, 0 62%)", Ee = "M50 3 44.5 2
       </div>
     `;
   }
+  /** The zone the visible date and clock render in: the application
+   *  timezone the admin stored (published on the household rollup by
+   *  custom_components/nestquest/sensor.py — ``timezone``).  Only when
+   *  none is stored does Home Assistant's zone (or the browser's) apply. */
   _timeZone() {
-    return kt(this.hass);
+    const e = this._state("sensor.nestquest_household_quests_due_today")?.attributes?.timezone;
+    return typeof e == "string" && e.trim() ? e.trim() : kt(this.hass);
   }
   _state(e) {
     const n = this.hass?.states?.[e];
@@ -1280,7 +1285,7 @@ const ze = "polygon(0 0, 100% 0, 100% 62%, 50% 100%, 0 62%)", Ee = "M50 3 44.5 2
       `sensor.nestquest_${e}_completion_pct_today`
     ), r = this._state(
       `binary_sensor.nestquest_${e}_present_today`
-    ), l = n?.attributes ?? {}, o = Te(te(n?.state, 0)), p = Te(te(s?.state, 0)), u = a ? te(a.state, Number.NaN) : Number.NaN, c = Number.isFinite(u) ? Se(u) : o > 0 ? Se(p / o * 100) : 0;
+    ), l = n?.attributes ?? {}, o = ze(te(n?.state, 0)), p = ze(te(s?.state, 0)), u = a ? te(a.state, Number.NaN) : Number.NaN, c = Number.isFinite(u) ? Se(u) : o > 0 ? Se(p / o * 100) : 0;
     let f = !0;
     const h = l.present;
     typeof h == "boolean" ? f = h : r && (f = String(r.state ?? "").trim().toLowerCase() === "on");
@@ -1293,7 +1298,7 @@ const ze = "polygon(0 0, 100% 0, 100% 62%, 50% 100%, 0 62%)", Ee = "M50 3 44.5 2
       typeof X == "string" && X.trim() && (m = X.trim());
     }
     m || (m = At(e));
-    const v = Tt(
+    const v = zt(
       r?.attributes?.next_present,
       this._timeZone()
     ), U = v ? `Returns ${ee(v, this._timeZone())}` : null;
@@ -1439,7 +1444,7 @@ const ze = "polygon(0 0, 100% 0, 100% 62%, 50% 100%, 0 62%)", Ee = "M50 3 44.5 2
           <span class="clock">${$t(this._now, this._timeZone())}</span>
         </div>
       `;
-    const t = zt(e.condition), n = Et(e.condition, t), s = e.temperature === null ? g : d`<span class="temp">${Math.round(e.temperature)}°</span>`, a = e.high === null || e.low === null ? null : `${Math.round(e.high)}° / ${Math.round(e.low)}°`;
+    const t = Tt(e.condition), n = Et(e.condition, t), s = e.temperature === null ? g : d`<span class="temp">${Math.round(e.temperature)}°</span>`, a = e.high === null || e.low === null ? null : `${Math.round(e.high)}° / ${Math.round(e.low)}°`;
     return d`
       <div class="dock">
         ${Dt}
@@ -3501,11 +3506,11 @@ const Ue = "polygon(0 0, 100% 0, 100% 62%, 50% 100%, 0 62%)", yn = "polygon(50%
   icon: qn,
   headline: "No adventurer chosen",
   body: "Open The Party and tap your crest to open your quest log."
-}, Tn = {
+}, zn = {
   icon: Mn,
   headline: "NestQuest is not set up yet",
   body: "A parent needs to finish setting up NestQuest."
-}, zn = {
+}, Tn = {
   icon: Cn,
   headline: "The records cannot be reached",
   body: "The party's records are quiet right now. NestQuest will return shortly."
@@ -3597,9 +3602,9 @@ const Ue = "polygon(0 0, 100% 0, 100% 62%, 50% 100%, 0 62%)", yn = "polygon(50%
       case "no-adventurer":
         return this._renderNotice(Sn);
       case "not-set-up":
-        return this._renderNotice(Tn);
-      case "unreachable":
         return this._renderNotice(zn);
+      case "unreachable":
+        return this._renderNotice(Tn);
       case "away": {
         const t = ["The quest log unlocks when they return."];
         return e.returns && t.push(`Returns ${e.returns}`), d`
@@ -3727,8 +3732,13 @@ const Ue = "polygon(0 0, 100% 0, 100% 62%, 50% 100%, 0 62%)", yn = "polygon(50%
       </div>
     `;
   }
+  /** The zone the visible date and clock render in: the application
+   *  timezone the admin stored (published on the household rollup by
+   *  custom_components/nestquest/sensor.py — ``timezone``).  Only when
+   *  none is stored does Home Assistant's zone (or the browser's) apply. */
   _timeZone() {
-    return rn(this.hass);
+    const e = this._state("sensor.nestquest_household_quests_due_today")?.attributes?.timezone;
+    return typeof e == "string" && e.trim() ? e.trim() : rn(this.hass);
   }
   _state(e) {
     const n = this.hass?.states?.[e];
diff --git a/frontend/src/cards/party-board.ts b/frontend/src/cards/party-board.ts
index 8a7c8eb..c28c977 100644
--- a/frontend/src/cards/party-board.ts
+++ b/frontend/src/cards/party-board.ts
@@ -937,8 +937,16 @@ export class NestQuestPartyBoardCard extends LitElement {
     `;
   }
 
+  /** The zone the visible date and clock render in: the application
+   *  timezone the admin stored (published on the household rollup by
+   *  custom_components/nestquest/sensor.py — ``timezone``).  Only when
+   *  none is stored does Home Assistant's zone (or the browser's) apply. */
   private _timeZone(): string | undefined {
-    return hassTimeZone(this.hass);
+    const stored = this._state("sensor.nestquest_household_quests_due_today")
+      ?.attributes?.timezone;
+    return typeof stored === "string" && stored.trim()
+      ? stored.trim()
+      : hassTimeZone(this.hass);
   }
 
   private _state(entityId: string): StateObject | null {
diff --git a/frontend/src/cards/quest-log.ts b/frontend/src/cards/quest-log.ts
index 9e49bfe..d3e5882 100644
--- a/frontend/src/cards/quest-log.ts
+++ b/frontend/src/cards/quest-log.ts
@@ -1749,8 +1749,16 @@ export class NestQuestQuestLogCard extends LitElement {
     `;
   }
 
+  /** The zone the visible date and clock render in: the application
+   *  timezone the admin stored (published on the household rollup by
+   *  custom_components/nestquest/sensor.py — ``timezone``).  Only when
+   *  none is stored does Home Assistant's zone (or the browser's) apply. */
   private _timeZone(): string | undefined {
-    return hassTimeZone(this.hass);
+    const stored = this._state("sensor.nestquest_household_quests_due_today")
+      ?.attributes?.timezone;
+    return typeof stored === "string" && stored.trim()
+      ? stored.trim()
+      : hassTimeZone(this.hass);
   }
 
   private _state(entityId: string): StateObject | null {
diff --git a/frontend/tests/render-party-board.mjs b/frontend/tests/render-party-board.mjs
index 4b0309f..59346d7 100644
--- a/frontend/tests/render-party-board.mjs
+++ b/frontend/tests/render-party-board.mjs
@@ -3,13 +3,15 @@
  *
  * Usage: node render-party-board.mjs < spec.json
  *
- * The spec JSON carries {bundle, tag, config, hass, url?, click_plate?};
+ * The spec JSON carries {bundle, tag, config, hass, url?, click_plate?, now?};
  * stdout receives one JSON object {plates, tappable, location, html} where
  * plates is the ordered plate list the shadow DOM renders (name +
  * present/away/unknown kind), tappable the plate names rendered as tappable
  * <button> plates, and location the window pathname after the optional plate
- * tap. The Python panel tests drive this harness so the assertions run
- * against the exact bundle HACS ships.
+ * tap. With now: <ISO instant> the card's clock is pinned there
+ * (argument-less new Date() and Date.now() return it; the process TZ
+ * decides its local wall time). The Python panel tests drive this harness
+ * so the assertions run against the exact bundle HACS ships.
  */
 import { readFileSync } from "node:fs";
 import { pathToFileURL } from "node:url";
@@ -39,6 +41,23 @@ globalThis.window = dom.window;
 // jsdom Event must shadow it for the dispatched event to be delivered.
 globalThis.Event = dom.window.Event;
 
+// Pin the clock: argument-less construction and Date.now() read `pinned`,
+// every other Date use is the real class.
+if (spec.now !== undefined) {
+  const pinned = new Date(spec.now).getTime();
+  const RealDate = Date;
+  class PinnedDate extends RealDate {
+    constructor(...args) {
+      super(...(args.length === 0 ? [pinned] : args));
+    }
+    static now() {
+      return pinned;
+    }
+  }
+  globalThis.Date = PinnedDate;
+  dom.window.Date = PinnedDate;
+}
+
 await import(pathToFileURL(spec.bundle).href);
 
 const element = document.createElement(spec.tag);
diff --git a/tests/conftest.py b/tests/conftest.py
index 1ae82cb..2204796 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -910,6 +910,7 @@ def coordinator_client_from_test_override():
             {
                 "today_iso": datetime.date.today().isoformat(),
                 "cycle_day": 0,
+                "timezone": "",
                 "children": [],
             }
         )
diff --git a/tests/test_api_admin_snapshot.py b/tests/test_api_admin_snapshot.py
index 52652ac..f976dac 100644
--- a/tests/test_api_admin_snapshot.py
+++ b/tests/test_api_admin_snapshot.py
@@ -165,7 +165,9 @@ async def test_admin_jwt_returns_documented_snapshot(
 
     Every field is asserted as an explicit literal, with ONE clock
     read for the request.  With no missed view in the real snapshot,
-    the admin body equals the panel body for the same household.
+    the admin body equals the panel body for the same household — the
+    panel body additionally carries the stored ``timezone`` its cards
+    format the visible date and clock in (unset here).
     """
     client = snapshot_household.client
     seed = snapshot_household.seed
@@ -241,7 +243,7 @@ async def test_admin_jwt_returns_documented_snapshot(
         "/api/v1/panel/snapshot", headers=_panel_headers()
     )
     assert panel.status_code == 200
-    assert panel.json() == body
+    assert panel.json() == {**body, "timezone": ""}
 
 
 async def test_admin_keeps_missed_instance_panel_omits_it(
diff --git a/tests/test_api_household_clock.py b/tests/test_api_household_clock.py
index 13c05f0..6fd2961 100644
--- a/tests/test_api_household_clock.py
+++ b/tests/test_api_household_clock.py
@@ -632,6 +632,24 @@ async def test_admin_saved_zone_is_authoritative_across_surfaces(
     assert delays[1] == pytest.approx(299)
 
 
+async def test_panel_snapshot_publishes_the_stored_zone(
+    household: SimpleNamespace,
+) -> None:
+    """The panel snapshot carries the stored application zone verbatim so
+    the cards format their visible date and clock in it — ``""`` until the
+    admin saves one, then exactly the saved zone."""
+    async def panel_zone() -> str:
+        response = await household.client.get(
+            "/api/v1/panel/snapshot", headers=_panel_headers()
+        )
+        assert response.status_code == 200
+        return response.json()["timezone"]
+
+    assert await panel_zone() == ""
+    await _set_zone(household, "Pacific/Auckland")
+    assert await panel_zone() == "Pacific/Auckland"
+
+
 # --- settings writes are serialised with planning and sweeping (TZ-003) ------
 #
 # A zone write racing the loop's own settings reads must never leave a
diff --git a/tests/test_binary_sensors.py b/tests/test_binary_sensors.py
index d7d7b80..09c67c8 100644
--- a/tests/test_binary_sensors.py
+++ b/tests/test_binary_sensors.py
@@ -60,6 +60,7 @@ def _payload(children) -> dict:
     return {
         "today_iso": "2026-09-23",
         "cycle_day": 0,
+        "timezone": "",
         "children": list(children),
     }
 
diff --git a/tests/test_complete_quest_proxy.py b/tests/test_complete_quest_proxy.py
index 4097b23..873374b 100644
--- a/tests/test_complete_quest_proxy.py
+++ b/tests/test_complete_quest_proxy.py
@@ -55,6 +55,7 @@ def _empty_snapshot() -> dict:
     return {
         "today_iso": "2026-09-23",
         "cycle_day": 0,
+        "timezone": "",
         "children": [],
     }
 
diff --git a/tests/test_coordinator.py b/tests/test_coordinator.py
index d7baf23..2fdb440 100644
--- a/tests/test_coordinator.py
+++ b/tests/test_coordinator.py
@@ -93,6 +93,7 @@ class FakeMonotonic:
 FIXTURE_SNAPSHOT = {
     "today_iso": _today_iso(),
     "cycle_day": 3,
+    "timezone": "",
     "children": [
         {
             "child_id": 1,
@@ -793,7 +794,12 @@ async def test_snapshot_from_api_payload_empty_household() -> None:
     """An empty household (no children) is a valid snapshot: empty
     children tuple, cycle day passes through."""
     snapshot = snapshot_from_api_payload(
-        {"today_iso": "2026-09-23", "cycle_day": 0, "children": []}
+        {
+            "today_iso": "2026-09-23",
+            "cycle_day": 0,
+            "timezone": "",
+            "children": [],
+        }
     )
     assert snapshot.children == ()
     assert snapshot.cycle_day == 0
diff --git a/tests/test_core_snapshot.py b/tests/test_core_snapshot.py
index 700f8a5..9e7c23d 100644
--- a/tests/test_core_snapshot.py
+++ b/tests/test_core_snapshot.py
@@ -332,6 +332,7 @@ async def test_build_snapshot_explicit_values(hass, make_entry, tmp_path) -> Non
             return {
                 "today_iso": built.today_iso,
                 "cycle_day": built.cycle_day,
+                "timezone": built.timezone,
                 "children": [
                     {
                         "child_id": child.child_id,
diff --git a/tests/test_entity_lifecycle.py b/tests/test_entity_lifecycle.py
index 4dd384f..3811129 100644
--- a/tests/test_entity_lifecycle.py
+++ b/tests/test_entity_lifecycle.py
@@ -67,6 +67,7 @@ def _payload(children) -> dict:
     return {
         "today_iso": "2026-09-23",
         "cycle_day": 0,
+        "timezone": "",
         "children": list(children),
     }
 
diff --git a/tests/test_entity_matrix.py b/tests/test_entity_matrix.py
index dcd9497..dc16a50 100644
--- a/tests/test_entity_matrix.py
+++ b/tests/test_entity_matrix.py
@@ -76,6 +76,7 @@ def _payload(children, cycle_day=0) -> dict:
     return {
         "today_iso": "2026-09-23",
         "cycle_day": cycle_day,
+        "timezone": "",
         "children": list(children),
     }
 
diff --git a/tests/test_events.py b/tests/test_events.py
index ac45112..4114e71 100644
--- a/tests/test_events.py
+++ b/tests/test_events.py
@@ -70,6 +70,7 @@ def _payload(children) -> dict:
     return {
         "today_iso": "2026-09-23",
         "cycle_day": 0,
+        "timezone": "",
         "children": list(children),
     }
 
diff --git a/tests/test_panel_cards.py b/tests/test_panel_cards.py
index 7065bbe..f65af8e 100644
--- a/tests/test_panel_cards.py
+++ b/tests/test_panel_cards.py
@@ -567,6 +567,8 @@ def _render_party_board(
     states: dict,
     url: str | None = None,
     click_plate: str | None = None,
+    now: str | None = None,
+    tz: str | None = None,
 ) -> dict:
     """Render the built bundle's party board and return its plates.
 
@@ -575,7 +577,9 @@ def _render_party_board(
     mounts the card with the given config and hass snapshot, optionally
     taps the named plate, and prints the ordered plates its shadow DOM
     renders, which of them are tappable buttons, and the pathname after
-    the optional tap.
+    the optional tap.  ``now`` pins the card's clock to an ISO instant
+    and ``tz`` sets the node process's ``TZ`` — the panel browser's
+    local zone.
     """
     assert BUNDLE_PATH.is_file(), "bundle missing: run cd frontend && npm run build"
     assert RENDER_HARNESS.is_file()
@@ -589,12 +593,15 @@ def _render_party_board(
         spec["url"] = url
     if click_plate is not None:
         spec["click_plate"] = click_plate
+    if now is not None:
+        spec["now"] = now
     completed = subprocess.run(
         ["node", str(RENDER_HARNESS)],
         input=json.dumps(spec),
         capture_output=True,
         text=True,
         timeout=120,
+        env={**os.environ, "TZ": tz} if tz is not None else None,
     )
     assert completed.returncode == 0, (
         f"render harness failed: {completed.stderr}"
@@ -1235,6 +1242,71 @@ def test_quest_log_overdue_follows_the_api_snapshot_not_the_panel_clock() -> Non
     assert after == {"42": overdue, "43": due_by}, after
 
 
+def test_panel_date_and_clock_follow_the_stored_application_timezone() -> None:
+    """The stored application timezone is the single source of local-time
+    truth for the panel's visible date and clock too: the household rollup
+    publishes it (``timezone``) and both cards format in it — the party
+    board's kicker and dock date and clock, the quest log's header date —
+    even though Home Assistant's zone and the panel browser's zone are both
+    UTC.  At 2026-09-29T23:30Z it is still Tuesday 11:30 PM in UTC but
+    already Wednesday 12:30 PM in Pacific/Auckland (NZDT)."""
+    generated = _generate_dashboard(
+        {}, _three_child_states(), url="http://homeassistant.local/nestquest"
+    )
+    states = _three_child_states()
+    states["sensor.nestquest_household_quests_due_today"]["attributes"][
+        "timezone"
+    ] = "Pacific/Auckland"
+    now = "2026-09-29T23:30:00Z"
+
+    def text(html: str) -> str:
+        return re.sub(r"<!--.*?-->", "", html).replace("\u202f", " ")
+
+    def board_date_and_clock(html: str) -> tuple[str, str, str]:
+        found = re.search(
+            r'<p class="kicker">The Party · (.*?)</p>.*?'
+            r'<span class="date">(.*?)</span>.*?<span class="clock">(.*?)</span>',
+            text(html),
+            re.DOTALL,
+        )
+        assert found is not None, html
+        return found.group(1), found.group(2), found.group(3)
+
+    board = _render_party_board(
+        generated["views"][0]["cards"][0], states, now=now, tz="UTC"
+    )["html"]
+    assert board_date_and_clock(board) == (
+        "Wednesday, Sep 30",
+        "Wednesday, Sep 30",
+        "12:30 PM",
+    )
+
+    log = _render_quest_log(
+        generated["views"][1]["cards"][0],
+        states,
+        url="http://homeassistant.local/nestquest/ada",
+        now=now,
+        tz="UTC",
+    )["html"]
+    sub = re.search(r'<p class="sub">\s*(.*?) ·', text(log), re.DOTALL)
+    assert sub is not None, log
+    assert sub.group(1) == "Wednesday, Sep 30"
+
+    # With no stored zone the documented fallback applies: Home
+    # Assistant's zone (UTC here) formats the same instant.
+    del states["sensor.nestquest_household_quests_due_today"]["attributes"][
+        "timezone"
+    ]
+    fallback = _render_party_board(
+        generated["views"][0]["cards"][0], states, now=now, tz="UTC"
+    )["html"]
+    assert board_date_and_clock(fallback) == (
+        "Tuesday, Sep 29",
+        "Tuesday, Sep 29",
+        "11:30 PM",
+    )
+
+
 def test_quest_log_crest_matches_the_spec_geometry() -> None:
     """PANEL-SPEC §3 header crest: 96x110 shield, 4px ring of
     rgba(255,255,255,.22) around the --nq-p-crest face, 44px/700 display
diff --git a/tests/test_sensors.py b/tests/test_sensors.py
index 7a54df0..a6b44cf 100644
--- a/tests/test_sensors.py
+++ b/tests/test_sensors.py
@@ -76,6 +76,7 @@ def _payload(children) -> dict:
     return {
         "today_iso": _today_iso(),
         "cycle_day": 0,
+        "timezone": "",
         "children": list(children),
     }
 
@@ -569,6 +570,22 @@ async def test_household_due_sensor_publishes_the_ordered_child_roster(
     }
 
 
+async def test_household_due_sensor_publishes_the_stored_zone(
+    hass, make_entry
+) -> None:
+    """The rollup carries the snapshot's stored application zone verbatim
+    (the panel cards format their date and clock in it); ``""`` — no zone
+    stored — passes through unchanged for the cards' documented fallback."""
+    zoned = {**_seeded_payload(), "timezone": "Pacific/Auckland"}
+    entry, coordinator, _client = await _setup_entry(
+        hass, make_entry, zoned, _seeded_payload()
+    )
+    rollup = hass.entities["nestquest_household_quests_due_today"]
+    assert rollup.extra_state_attributes["timezone"] == "Pacific/Auckland"
+    await coordinator.async_refresh()
+    assert rollup.extra_state_attributes["timezone"] == ""
+
+
 async def test_household_roster_tracks_the_snapshot_on_refresh(
     hass, make_entry
 ) -> None:
diff --git a/tests/test_sse_subscription.py b/tests/test_sse_subscription.py
index 0a5c26d..e0b0b62 100644
--- a/tests/test_sse_subscription.py
+++ b/tests/test_sse_subscription.py
@@ -151,7 +151,12 @@ DOCUMENTED_FIELDS = {
 
 #: A minimal panel snapshot payload for the full-setup wiring tests
 #: (the shape ``snapshot_from_api_payload`` consumes; no children).
-MINIMAL_SNAPSHOT = {"today_iso": "2026-09-23", "cycle_day": 1, "children": []}
+MINIMAL_SNAPSHOT = {
+    "today_iso": "2026-09-23",
+    "cycle_day": 1,
+    "timezone": "",
+    "children": [],
+}
 
 
 # ---------------------------------------------------------------------------