fix(vorsorge): key due status on the local calendar day

src/components/measurement-reminders/__tests__/vorsorge-section.test.tsx

@@ -136,6 +136,68 @@ describe("<VorsorgeSection> loading + empty", () => {
     expect(html).not.toContain("Log value");
   });
 
+  it("reads a same-day due time as 'today' (calendar-day delta, not rolling 24h)", () => {
+    // v1.18.9 recon — a reminder whose nextDue falls on the SAME local
+    // calendar day must read "Due today" with the green status hue, even when
+    // the wall-clock gap to now exceeds the 24h a rolling delta would key on.
+    // Anchor the due instant to local noon today so the floored calendar-day
+    // delta is 0 regardless of the hour the suite runs.
+    const todayNoon = new Date();
+    todayNoon.setHours(12, 0, 0, 0);
+    const reminder: MeasurementReminder = {
+      id: "due-today",
+      label: "Blood pressure check",
+      measurementType: "BLOOD_PRESSURE_SYS",
+      intervalDays: 7,
+      rrule: null,
+      anchorDate: null,
+      endsOn: null,
+      origin: "VORSORGE",
+      nextDueAt: todayNoon.toISOString(),
+      notifyHour: 9,
+      location: null,
+      lastSatisfiedAt: null,
+      enabled: true,
+      createdAt: "2030-01-01T00:00:00.000Z",
+      updatedAt: "2030-01-01T00:00:00.000Z",
+    } as MeasurementReminder;
+    remindersMock.mockReturnValue({ data: [reminder], isLoading: false });
+    const html = render(<VorsorgeSection />);
+    expect(html).toContain("Due today");
+    // The status hue is the discreet success colour, never a card-bg tint.
+    expect(html).toContain("text-success");
+  });
+
+  it("reads a prior-day due time as 'overdue' once the calendar day has passed", () => {
+    // A reminder whose due CALENDAR day is before today reads "Overdue", with
+    // the warning hue — a rolling-24h delta would mis-bucket a yesterday-evening
+    // due viewed this morning as "today".
+    const yesterday = new Date();
+    yesterday.setDate(yesterday.getDate() - 1);
+    yesterday.setHours(20, 0, 0, 0);
+    const reminder: MeasurementReminder = {
+      id: "overdue",
+      label: "Annual physical",
+      measurementType: null,
+      intervalDays: 365,
+      rrule: null,
+      anchorDate: null,
+      endsOn: null,
+      origin: "VORSORGE",
+      nextDueAt: yesterday.toISOString(),
+      notifyHour: 9,
+      location: null,
+      lastSatisfiedAt: null,
+      enabled: true,
+      createdAt: "2030-01-01T00:00:00.000Z",
+      updatedAt: "2030-01-01T00:00:00.000Z",
+    } as MeasurementReminder;
+    remindersMock.mockReturnValue({ data: [reminder], isLoading: false });
+    const html = render(<VorsorgeSection />);
+    expect(html).toContain("Overdue by 1 days");
+    expect(html).toContain("text-warning");
+  });
+
   it("translates a COACH-origin label i18n key and shows the neutral badge", () => {
     const reminder: MeasurementReminder = {
       id: "c1",

src/components/measurement-reminders/vorsorge-section.tsx

@@ -40,6 +40,7 @@ import {
 
 import { useFormatters, useTranslations } from "@/lib/i18n/context";
 import { relativeCalendarDate } from "@/lib/i18n/relative-time";
+import { startOfLocalDayInTz } from "@/lib/tz/local-day";
 import { cn } from "@/lib/utils";
 import { applyOrder, useModuleListPrefs } from "@/lib/module-list-prefs";
 import { SettingsCardHeader } from "@/components/settings/_card-header";
@@ -124,9 +125,17 @@ function relativeDueKey(
   now: number,
 ): { key: string; days: number } {
   if (!nextDueAt) return { key: "nextDue.none", days: 0 };
-  const due = new Date(nextDueAt).getTime();
-  // Compare calendar-day deltas so "today" / "in 1 day" read cleanly.
-  const deltaDays = Math.round((due - now) / DAY_MS);
+  const due = new Date(nextDueAt);
+  if (Number.isNaN(due.getTime())) return { key: "nextDue.none", days: 0 };
+  // v1.18.9 (recon) — compare CALENDAR-day deltas in the user's local zone,
+  // not a rolling-24h delta. A reminder due at 09:00 viewed the same evening
+  // at 20:00 must still read "heute", and one whose due calendar-day is before
+  // today must read "überfällig" — a raw `(due - now) / DAY_MS` round would
+  // mis-bucket both. Floor each instant to its local day start (host-local zone
+  // = the browser user's zone for this client component) before differencing.
+  const dueDay = startOfLocalDayInTz(due, undefined).getTime();
+  const nowDay = startOfLocalDayInTz(new Date(now), undefined).getTime();
+  const deltaDays = Math.round((dueDay - nowDay) / DAY_MS);
   if (deltaDays < 0) return { key: "overdueByDays", days: Math.abs(deltaDays) };
   if (deltaDays === 0) return { key: "nextDue.today", days: 0 };
   if (deltaDays === 1) return { key: "nextDue.tomorrow", days: 1 };