Manual timezone is the single source of local-time truth (task 7e173881) (#285)

Co-authored-by: dev_agent <dev_agent@cubecraftlabs.com>
Co-committed-by: dev_agent <dev_agent@cubecraftlabs.com>

admin/src/schedule/OverrideEditor.test.tsx

@@ -74,6 +74,10 @@ 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 application timezone first ("" = none published).
+  if (path.endsWith("/admin/settings")) {
+    return jsonResponse({ timezone: "", effective_timezone: "" });
+  }
   if (path.endsWith("/admin/children")) return jsonResponse({ children: CHILDREN });
   const patternsMatch = /\/children\/(\d+)\/presence-patterns$/.exec(path);
   if (patternsMatch) {

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, effective_timezone = timezone) {
+    fetchMock = vi.fn(async (url: string, init?: RequestInit) =>
+      String(url).endsWith("/api/v1/admin/settings")
+        ? jsonResponse({ timezone, effective_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 today in the API host's published 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");
+  });
+});

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);

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);