Merge branch 'fix/tz-correctness' into release/v1.27.30

src/components/insights/__tests__/hero-strip.test.tsx

@@ -33,11 +33,13 @@ const sampleBriefing: DailyBriefingPayload = {
   keyFindings: [],
 };
 
-// `getHours()` reads from the local representation. Force a known
-// local hour by constructing from a local-time fields tuple.
-const morningLocal = new Date(2026, 4, 10, 9, 0, 0); // May 10, 09:00 local
-const afternoonLocal = new Date(2026, 4, 10, 14, 0, 0); // May 10, 14:00 local
-const eveningLocal = new Date(2026, 4, 10, 20, 0, 0); // May 10, 20:00 local
+// The greeting bucket is now computed in the user's configured zone
+// (the mocked `Europe/Berlin`), not the host's — so pin explicit UTC
+// instants and translate them to the intended Berlin wall-clock hour.
+// May 10 2026 is CEST (UTC+2), so Berlin = UTC + 2h.
+const morningLocal = new Date("2026-05-10T07:00:00Z"); // 09:00 Berlin
+const afternoonLocal = new Date("2026-05-10T12:00:00Z"); // 14:00 Berlin
+const eveningLocal = new Date("2026-05-10T18:00:00Z"); // 20:00 Berlin
 
 describe("<HeroStrip>", () => {
   it("renders the slot wrapper + Dracula gradient utility", () => {
@@ -178,9 +180,10 @@ describe("<HeroStrip>", () => {
   });
 
   it("uses the now override deterministically (smoke for greeting-bucket logic)", () => {
-    // Five different hours map to four different greeting buckets:
-    // 09:00 → morning, 14:00 → afternoon, 20:00 → evening, 02:00 → night.
-    const earlyMorning = new Date(2026, 4, 10, 2, 0, 0);
+    // Buckets are read in the mocked user's Berlin zone: 09:00 → morning,
+    // 14:00 → afternoon, 20:00 → evening, 02:00 → night. 00:00 UTC is
+    // 02:00 Berlin (CEST).
+    const earlyMorning = new Date("2026-05-10T00:00:00Z"); // 02:00 Berlin
     const html = render(<HeroStrip briefing={null} now={earlyMorning} />);
     // Night maps to "Good evening" in EN per the resolver mapping.
     expect(html).toContain("Good evening");
@@ -188,12 +191,24 @@ describe("<HeroStrip>", () => {
     expect(html).not.toContain("Good morning");
   });
 
-  it("uses the morning bucket at noon-1 (11:59 boundary)", () => {
-    const justBeforeNoon = new Date(2026, 4, 10, 11, 59, 0);
+  it("uses the morning bucket at noon-1 (11:59 Berlin boundary)", () => {
+    const justBeforeNoon = new Date("2026-05-10T09:59:00Z"); // 11:59 Berlin
     const html = render(<HeroStrip briefing={null} now={justBeforeNoon} />);
     expect(html).toContain("Good morning");
   });
 
+  it("resolves the greeting hour in the user's stored zone, not the browser", () => {
+    // 11:30 UTC is still MORNING in UTC but 13:30 (AFTERNOON) in the mocked
+    // Berlin user's zone. The afternoon greeting proves the hour comes from
+    // the stored zone — the /insights hero used to read the browser clock.
+    const utcMorningBerlinAfternoon = new Date("2026-05-10T11:30:00Z");
+    const html = render(
+      <HeroStrip briefing={null} now={utcMorningBerlinAfternoon} />,
+    );
+    expect(html).toContain("Good afternoon");
+    expect(html).not.toContain("Good morning");
+  });
+
   // ── B4 — Weekly-report banner card ─────────────────────────────────
   // v1.4.28 retired the weekly-report path. The banner, the report
   // route, the schema slot and the i18n keys are gone; the hero

src/components/insights/hero-strip.tsx

@@ -7,6 +7,7 @@ import { useTranslations, useFormatters } from "@/lib/i18n/context";
 import { formatUpdatedLabel } from "@/lib/i18n/relative-time";
 import { useAuth } from "@/hooks/use-auth";
 import { useModuleEnabled } from "@/hooks/use-module-enabled";
+import { hourInTz, DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { ProseBlocks } from "@/components/insights/prose-blocks";
 import { cn } from "@/lib/utils";
 import {
@@ -138,8 +139,7 @@ interface HeroStripProps {
  *                        rare to see /insights at 03:00 and "Guten
  *                        Morgen" pre-5am reads odd)
  */
-function resolveGreetingKey(now: Date): string {
-  const hour = now.getHours();
+function resolveGreetingKey(hour: number): string {
   if (hour >= 5 && hour < 12) return "insights.heroGreetingMorning";
   if (hour >= 12 && hour < 18) return "insights.heroGreetingAfternoon";
   // 18:00-22:59 maps to "Good evening"; 23:00-04:59 also maps to
@@ -221,7 +221,14 @@ export function HeroStrip({
   // pillar from the number itself). SSR-safe + default-on, matching the
   // disabled-allowlist gate.
   const moodEnabled = useModuleEnabled("mood");
-  const greetingKey = resolveGreetingKey(now ?? new Date());
+  // Greeting hour in the user's configured zone, not the browser's — a
+  // traveller / VPN user / wrong device clock otherwise sees the wrong
+  // salutation. Mirrors the dashboard hero (`hourInTimezone(now, userTz)`).
+  const greetingHour = hourInTz(
+    now ?? new Date(),
+    user?.timezone ?? DEFAULT_TIMEZONE,
+  );
+  const greetingKey = resolveGreetingKey(greetingHour);
   const greetingBase = t(greetingKey);
   const greeting = userName ? `${greetingBase}, ${userName}` : greetingBase;
   const subtitle = briefing?.paragraph ?? t("insights.heroFallbackSubtitle");

src/lib/analytics/__tests__/compliance-bundle.test.ts

@@ -23,6 +23,8 @@ import {
   tallyLedgerRows,
   type ComplianceSchedule,
 } from "../compliance";
+import type { DoseHistoryRow } from "@/lib/medications/scheduling/dose-history";
+import { zonedWallClockToUtc } from "@/lib/tz/wall-clock";
 
 const TZ = "UTC";
 const DAY_MS = 24 * 60 * 60 * 1000;
@@ -273,7 +275,7 @@ describe("dailyComplianceRatesFromLedger — cadence-aware per-day series", () =
       (r) =>
         r.at.getTime() >= from.getTime() && r.at.getTime() <= NOW.getTime(),
     );
-    const series = dailyComplianceRatesFromLedger(windowRows);
+    const series = dailyComplianceRatesFromLedger(windowRows, TZ);
 
     // Only the Mondays in the window produce a point — Tuesday…Sunday emit
     // nothing, so a 7×-denser daily denominator can never drag the rate down.
@@ -319,7 +321,7 @@ describe("dailyComplianceRatesFromLedger — cadence-aware per-day series", () =
       (r) =>
         r.at.getTime() >= from.getTime() && r.at.getTime() <= NOW.getTime(),
     );
-    const series = dailyComplianceRatesFromLedger(windowRows);
+    const series = dailyComplianceRatesFromLedger(windowRows, TZ);
 
     // Still one point per due Monday — never a point on a non-due weekday.
     // Five Mondays in the window; the skipped take leaves one as a miss.
@@ -334,6 +336,41 @@ describe("dailyComplianceRatesFromLedger — cadence-aware per-day series", () =
     const aggregateRate = Math.round((taken / (taken + missed)) * 100);
     expect(aggregateRate).toBe(bundle.compliance30.rate);
   });
+
+  it("buckets a non-Berlin user's two same-local-day doses into ONE day", () => {
+    // America/Los_Angeles user, twice-daily 08:00 + 20:00 LOCAL on the same
+    // local calendar day (2026-06-15). The 20:00 PDT dose is 03:00 UTC the
+    // NEXT day — and 05:00 the next Berlin day — so a fixed-Berlin day key
+    // splits one local day's two doses across two buckets.
+    const takenOnTime = (h: number, m: number): DoseHistoryRow => {
+      const at = zonedWallClockToUtc(
+        { year: 2026, month: 6, day: 15, hour: h, minute: m },
+        "America/Los_Angeles",
+      );
+      return {
+        kind: "slot",
+        at,
+        timeOfDay: `${String(h).padStart(2, "0")}:${String(m).padStart(2, "0")}`,
+        status: "taken_on_time",
+        intake: null,
+      };
+    };
+    const rows: DoseHistoryRow[] = [takenOnTime(8, 0), takenOnTime(20, 0)];
+
+    // Bucketed in the user's own zone: one local day, two taken.
+    const laSeries = dailyComplianceRatesFromLedger(
+      rows,
+      "America/Los_Angeles",
+    );
+    expect(laSeries.length).toBe(1);
+    expect(laSeries[0].taken).toBe(2);
+    expect(laSeries[0].rate).toBe(100);
+
+    // Sanity: the fixed-Berlin key (the pre-fix behaviour) would split these
+    // same two doses across two calendar buckets — the defect the fix closes.
+    const berlinSeries = dailyComplianceRatesFromLedger(rows, "Europe/Berlin");
+    expect(berlinSeries.length).toBe(2);
+  });
 });
 
 describe("tallyLedgerRows — windowed tallies over one shared ledger", () => {

src/lib/analytics/__tests__/compliance.test.ts

@@ -1367,6 +1367,28 @@ describe("classifyIntakeTiming", () => {
       "very_late",
     );
   });
+
+  it("interprets the window HH:mm in the supplied tz (non-UTC user)", () => {
+    // America/Los_Angeles is UTC-7 in summer. An "08:00" slot means 08:00
+    // LOCAL = 15:00 UTC on 2026-06-15; a dose taken 15 min into the window
+    // is 15:15 UTC. The slot's canonical instant is the anchor date.
+    const slotInstant = new Date("2026-06-15T15:00:00Z"); // 08:00 LA
+    const takenAt = new Date("2026-06-15T15:15:00Z"); // 08:15 LA
+
+    // With the user's zone the dose is on time.
+    expect(
+      classifyIntakeTiming(takenAt, "08:00", "09:00", slotInstant, {
+        tz: "America/Los_Angeles",
+      }),
+    ).toBe("on_time");
+
+    // Without a tz the window HH:mm is read as UTC (08:00 UTC), so the very
+    // same on-time dose reads as 7h15m off — very_late. This is the defect
+    // the achievements perfect-day check hit for users far from UTC.
+    expect(classifyIntakeTiming(takenAt, "08:00", "09:00", slotInstant)).toBe(
+      "very_late",
+    );
+  });
 });
 
 // v1.8.5 — the cadence-density rule + the per-dose uptime strip.

src/lib/analytics/compliance.ts

@@ -52,7 +52,8 @@ import {
   type RecurrenceContext,
   type ScheduleType,
 } from "@/lib/medications/scheduling/recurrence";
-import { toBerlinDayKey } from "@/lib/tz/resolver";
+import { userDayKey } from "@/lib/tz/resolver";
+import { localHmAsUtc } from "@/lib/tz/local-day";
 
 export interface IntakeEvent {
   takenAt: Date | null;
@@ -126,10 +127,19 @@ function parseHHmm(time: string): { hours: number; minutes: number } {
 }
 
 /**
- * Build a Date for a given "HH:mm" on a specific date.
+ * Build the UTC instant of local "HH:mm" on the calendar day `day` falls on.
+ *
+ * When `tz` is supplied the window `HH:mm` is interpreted in the user's zone
+ * (via {@link localHmAsUtc}) on the local day of `day` — so an "08:00" slot is
+ * 08:00 LOCAL, not 08:00 UTC. Without `tz` it keeps the legacy UTC anchoring
+ * (`setUTCHours`), which is only correct for a UTC user; a caller far from UTC
+ * must pass its zone or the punctuality band is offset by the zone's offset.
  */
-function toDateOnDay(time: string, day: Date): Date {
+function toDateOnDay(time: string, day: Date, tz?: string): Date {
   const { hours, minutes } = parseHHmm(time);
+  if (tz) {
+    return localHmAsUtc(day, tz, hours, minutes);
+  }
   const d = new Date(day);
   d.setUTCHours(hours, minutes, 0, 0);
   return d;
@@ -157,18 +167,21 @@ function toDateOnDay(time: string, day: Date): Date {
  * @param options.lateMinutes Width of the `late` band beyond the 3-hour
  *   on-time tolerance, in minutes. Defaults to 120. Doses past this
  *   tail land in `very_late`.
+ * @param options.tz IANA zone the window `HH:mm` is interpreted in. Supply
+ *   the user's zone so an "08:00" slot means 08:00 LOCAL; omitting it keeps
+ *   the legacy UTC interpretation (correct only for a UTC user).
  */
 export function classifyIntakeTiming(
   takenAt: Date | null,
   windowStart: string, // "HH:mm"
   windowEnd: string, // "HH:mm"
   scheduledDate: Date, // the date this was scheduled
-  options?: { lateMinutes?: number },
+  options?: { lateMinutes?: number; tz?: string },
 ): IntakeTimingClass {
   if (takenAt === null) return "missed";
 
-  const start = toDateOnDay(windowStart, scheduledDate);
-  let end = toDateOnDay(windowEnd, scheduledDate);
+  const start = toDateOnDay(windowStart, scheduledDate, options?.tz);
+  let end = toDateOnDay(windowEnd, scheduledDate, options?.tz);
 
   // Handle overnight windows (e.g. windowStart="23:00", windowEnd="01:00")
   if (end <= start) {
@@ -1967,9 +1980,16 @@ export interface DailyComplianceRate {
  * rows (the window hasn't opened) are dropped before grouping, exactly as the
  * window tally excludes them. A day whose only ledger rows are skips yields no
  * point (zero denominator) rather than a misleading 0%.
+ *
+ * Days are bucketed in the USER's timezone (`tz`). Passing the caller's real
+ * zone keeps an evening dose on the local day it was actually due: a fixed
+ * Berlin key filed a `20:00 America/Los_Angeles` dose (04:00 UTC next day)
+ * into the following Berlin day, splitting one local day's two doses across
+ * two buckets and skewing every per-day rate for non-Berlin users.
  */
 export function dailyComplianceRatesFromLedger(
   ledgerRows: DoseHistoryRow[],
+  tz: string,
 ): DailyComplianceRate[] {
   const byDay = new Map<
     string,
@@ -1987,7 +2007,7 @@ export function dailyComplianceRatesFromLedger(
     // counter — they never enter the day's denominator.
     if (!isTaken && !isMissed) continue;
 
-    const dayKey = toBerlinDayKey(row.at);
+    const dayKey = userDayKey(row.at, tz);
     const bucket = byDay.get(dayKey) ?? { taken: 0, missed: 0, date: row.at };
     if (isTaken) bucket.taken += 1;
     else bucket.missed += 1;

src/lib/analytics/schedule-anchored-compliance.ts

@@ -27,6 +27,7 @@ import {
   buildComplianceMedicationContext,
   expectedSlotCountForDay,
   lastNonSkippedTakenAt,
+  SCHEDULE_COMPLIANCE_SELECT,
 } from "@/lib/analytics/compliance";
 import { getUserTodayBounds } from "@/lib/tz/local-day";
 import { userDayKey } from "@/lib/tz/resolver";
@@ -50,7 +51,9 @@ export async function buildScheduleAnchoredComplianceBuckets(
   const medications = await prisma.medication.findMany({
     where: { userId, active: true },
     include: {
-      schedules: true,
+      // v1.15.20 — the shared compliance select so a future engine column
+      // reaches this surface the moment it joins SCHEDULE_COMPLIANCE_SELECT.
+      schedules: { select: SCHEDULE_COMPLIANCE_SELECT },
       // v1.16.3 — archived schedule eras for era-aware expected counts.
       scheduleRevisions: { orderBy: { validFrom: "asc" } },
       // v1.25 H-MED1 — pause eras so paused days drop out of the denominator.

src/lib/doctor-report-data.ts

@@ -47,6 +47,7 @@ import {
   buildComplianceMedicationContext,
   lastNonSkippedTakenAt,
   tallyComplianceFromLedger,
+  SCHEDULE_COMPLIANCE_SELECT,
   type ComplianceSchedule,
   type IntakeEvent,
   type MedicationPauseEraLike,
@@ -828,7 +829,10 @@ export async function collectDoctorReportData(
       prisma.medication.findMany({
         where: { userId, active: true },
         include: {
-          schedules: true,
+          // v1.15.20 — the shared compliance select (plus `label`, which the
+          // FHIR schedule mapping below needs) so a future engine column added
+          // to SCHEDULE_COMPLIANCE_SELECT reaches the doctor-report surface.
+          schedules: { select: { ...SCHEDULE_COMPLIANCE_SELECT, label: true } },
           // v1.17 W1a — archived schedule eras so the ledger compliance
           // builder segments expected-slot expansion against the schedule
           // that was live on each past day (matches the detail page).

src/lib/gamification/achievements-result.ts

@@ -40,6 +40,7 @@ import {
   classifyPulse,
 } from "@/lib/analytics/classifications";
 import { classifyIntakeTiming } from "@/lib/analytics/compliance";
+import { wallClockInTz } from "@/lib/tz/wall-clock";
 
 export type AuthedUser = Awaited<ReturnType<typeof requireAuth>>["user"];
 
@@ -270,6 +271,7 @@ function getHealthGreenDaySeries(
 function getOnTimePerfectDaySeries(
   intakeEvents: IntakeEventRecord[],
   schedulesByMedicationId: Map<string, MedicationScheduleRecord[]>,
+  tz: string,
 ) {
   const eventsByDay = new Map<string, IntakeEventRecord[]>();
 
@@ -285,7 +287,6 @@ function getOnTimePerfectDaySeries(
   for (const [dayKey, events] of eventsByDay.entries()) {
     if (events.length === 0) continue;
 
-    const scheduledDate = dayKeyToDate(dayKey);
     let isPerfectDay = true;
 
     for (const event of events) {
@@ -299,9 +300,11 @@ function getOnTimePerfectDaySeries(
         continue;
       }
 
-      const eventMinutes =
-        event.scheduledFor.getUTCHours() * 60 +
-        event.scheduledFor.getUTCMinutes();
+      // The scheduled minute-of-day must be read in the user's zone: the raw
+      // `getUTCHours()` would push a non-UTC user's on-time dose past the 3h
+      // grace and misread a genuinely-perfect day as imperfect.
+      const scheduledWall = wallClockInTz(event.scheduledFor, tz);
+      const eventMinutes = scheduledWall.hour * 60 + scheduledWall.minute;
 
       let bestSchedule = schedules[0];
       let bestDistance = Infinity;
@@ -316,11 +319,15 @@ function getOnTimePerfectDaySeries(
         }
       }
 
+      // Classify punctuality against the slot's real local day: pass the
+      // canonical instant as the anchor and the user's zone so the window
+      // `HH:mm` resolves to the correct local wall time, not 08:00 UTC.
       const timing = classifyIntakeTiming(
         event.takenAt,
         bestSchedule.windowStart,
         bestSchedule.windowEnd,
-        scheduledDate,
+        event.scheduledFor,
+        { tz },
       );
 
       // v1.4.34 IW-C — `early` is also a compliant bucket (dose taken
@@ -722,6 +729,7 @@ export async function buildAchievementsResult(
   const onTimeSeries = getOnTimePerfectDaySeries(
     intakeEvents,
     schedulesByMedicationId,
+    user.timezone,
   );
   const complianceSeries = getCompliance80DaySeries(
     intakeEvents,

src/lib/insights/medication-compliance-status.ts

@@ -297,12 +297,13 @@ export async function prepareMedicationComplianceStatusForUser(
     // calendar day as fully dose-due — which made a weekly-cadence med's
     // per-day series contradict its own compliance30. Reusing the canonical
     // ledger fixes that by construction.
-    const perDayRecords = dailyComplianceRatesFromLedger(bundle.ledgerRows).map(
-      (day) => ({
-        measuredAt: day.date,
-        value: round(day.rate, 1),
-      }),
-    );
+    const perDayRecords = dailyComplianceRatesFromLedger(
+      bundle.ledgerRows,
+      userTz,
+    ).map((day) => ({
+      measuredAt: day.date,
+      value: round(day.rate, 1),
+    }));
 
     // `applyPayloadBudget` gives the latest-day focus; the compact
     // graded series is what reaches the prompt.

src/lib/tz/__tests__/local-day.test.ts

@@ -1,7 +1,9 @@
 import { describe, expect, it } from "vitest";
-import { startOfLocalDayInTz } from "@/lib/tz/local-day";
+import { getUserTodayBounds, startOfLocalDayInTz } from "@/lib/tz/local-day";
 import { wallClockInTz, zonedWallClockToUtc } from "@/lib/tz/wall-clock";
 
+const HOUR_MS = 60 * 60 * 1000;
+
 describe("zonedWallClockToUtc", () => {
   it("resolves a wall clock in a positive-offset zone to the right UTC instant", () => {
     // 00:30 CEST (UTC+2) on 2026-05-11 → 22:30 UTC on 2026-05-10.
@@ -82,3 +84,70 @@ describe("startOfLocalDayInTz", () => {
     expect(floor.getDate()).toBe(15);
   });
 });
+
+describe("getUserTodayBounds — DST-safe local-day window", () => {
+  it("spans a full 24h on an ordinary (non-transition) day", () => {
+    const now = new Date("2026-06-15T14:30:00.000Z");
+    const { start, end } = getUserTodayBounds(now, "Europe/Berlin");
+    // Berlin is CEST (UTC+2) in June: local midnight = 2026-06-14T22:00Z.
+    expect(start.toISOString()).toBe("2026-06-14T22:00:00.000Z");
+    // Inclusive end is the last ms before the next local midnight.
+    expect(end.getTime() - start.getTime()).toBe(24 * HOUR_MS - 1);
+  });
+
+  it("fall-back day is 25h and keeps a 23:30-local dose inside 'today'", () => {
+    // Europe/Berlin falls back 2026-10-25 03:00→02:00 (a 25-hour local day).
+    // A read taken at 23:30 local that evening.
+    const now = zonedWallClockToUtc(
+      { year: 2026, month: 10, day: 25, hour: 23, minute: 30 },
+      "Europe/Berlin",
+    );
+    const { start, end } = getUserTodayBounds(now, "Europe/Berlin");
+
+    // The window covers the real 25-hour local day, not a hardcoded 24h.
+    expect(end.getTime() - start.getTime()).toBe(25 * HOUR_MS - 1);
+
+    // The 23:30 dose — which the old 24h window dropped off the med cards —
+    // now falls inside [start, end].
+    const dose2330 = zonedWallClockToUtc(
+      { year: 2026, month: 10, day: 25, hour: 23, minute: 30 },
+      "Europe/Berlin",
+    );
+    expect(dose2330.getTime()).toBeGreaterThanOrEqual(start.getTime());
+    expect(dose2330.getTime()).toBeLessThanOrEqual(end.getTime());
+
+    // Both bounds sit at local midnight of their respective calendar days.
+    expect(wallClockInTz(start, "Europe/Berlin").hour).toBe(0);
+    expect(wallClockInTz(start, "Europe/Berlin").day).toBe(25);
+  });
+
+  it("spring-forward day is 23h and does not bleed into tomorrow's 00:30 dose", () => {
+    // Europe/Berlin springs forward 2026-03-29 02:00→03:00 (a 23-hour day).
+    const now = zonedWallClockToUtc(
+      { year: 2026, month: 3, day: 29, hour: 20, minute: 0 },
+      "Europe/Berlin",
+    );
+    const { start, end } = getUserTodayBounds(now, "Europe/Berlin");
+
+    // The window covers only the real 23-hour local day.
+    expect(end.getTime() - start.getTime()).toBe(23 * HOUR_MS - 1);
+
+    // Tomorrow's 00:30 dose belongs to 2026-03-30, so it must fall OUTSIDE
+    // today — the old fixed-24h window double-counted it as "today".
+    const tomorrow0030 = zonedWallClockToUtc(
+      { year: 2026, month: 3, day: 30, hour: 0, minute: 30 },
+      "Europe/Berlin",
+    );
+    expect(tomorrow0030.getTime()).toBeGreaterThan(end.getTime());
+  });
+
+  it("is correct for a negative-offset zone (America/Los_Angeles)", () => {
+    // 2026-06-15 20:00 PDT (UTC-7) → 2026-06-16T03:00Z. The local day is
+    // still the 15th, so the window must anchor on LA's 2026-06-15 midnight.
+    const now = new Date("2026-06-16T03:00:00.000Z");
+    const { start, end } = getUserTodayBounds(now, "America/Los_Angeles");
+    expect(start.toISOString()).toBe("2026-06-15T07:00:00.000Z");
+    expect(end.getTime() - start.getTime()).toBe(24 * HOUR_MS - 1);
+    expect(wallClockInTz(start, "America/Los_Angeles").day).toBe(15);
+  });
+});

src/lib/tz/__tests__/resolver.test.ts

@@ -23,6 +23,7 @@ import {
   formatInUserTz,
   invalidateServerDefaultTimezone,
   invalidateUserTimezone,
+  hourInTz,
   isNearUtc,
   isValidTimezone,
   resolveServerDefaultTimezone,
@@ -262,6 +263,30 @@ describe("userDayKey", () => {
   });
 });
 
+describe("hourInTz", () => {
+  it("reads the wall-clock hour in the user's zone, not UTC", () => {
+    // 2026-06-15T03:00Z is 20:00 the previous day in Los Angeles (UTC-7),
+    // 05:00 in Berlin (UTC+2), 12:00 in Tokyo (UTC+9).
+    const instant = new Date("2026-06-15T03:00:00.000Z");
+    expect(hourInTz(instant, "UTC")).toBe(3);
+    expect(hourInTz(instant, "America/Los_Angeles")).toBe(20);
+    expect(hourInTz(instant, "Europe/Berlin")).toBe(5);
+    expect(hourInTz(instant, "Asia/Tokyo")).toBe(12);
+  });
+
+  it("normalises local midnight to 0, never 24", () => {
+    const instant = new Date("2026-06-14T22:00:00.000Z"); // 00:00 Berlin
+    expect(hourInTz(instant, "Europe/Berlin")).toBe(0);
+  });
+
+  it("falls back to the default zone for an unusable tz string", () => {
+    // Mirrors formatInUserTz / userDayKey: an invalid zone degrades to
+    // DEFAULT_TIMEZONE (Europe/Berlin), which is UTC+2 in summer.
+    const instant = new Date("2026-06-15T09:00:00.000Z");
+    expect(hourInTz(instant, "Mars/Olympus")).toBe(11);
+  });
+});
+
 describe("isNearUtc", () => {
   // Pin a summer-side instant so DST is on for Berlin (+2) and off for
   // most southern-hemisphere zones — keeps the assertions readable.

src/lib/tz/format.ts

@@ -191,6 +191,18 @@ export function userDayKey(date: Date, tz: string): string {
   return formatInUserTz(date, tz, "date");
 }
 
+/**
+ * Wall-clock hour (0–23) an observer in `tz` reads off the clock at
+ * `date`. Used for the time-of-day greeting so a traveller whose device
+ * clock differs from their configured HealthLog zone still sees the right
+ * salutation. Falls back to the UTC hour if the zone is unusable.
+ */
+export function hourInTz(date: Date, tz: string): number {
+  const safeTz = isValidTimezone(tz) ? tz : DEFAULT_TIMEZONE;
+  const parsed = parseInt(wallClockParts(date, safeTz).hour, 10);
+  return Number.isFinite(parsed) ? parsed % 24 : date.getUTCHours();
+}
+
 interface WallClockParts {
   year: string;
   month: string;

src/lib/tz/local-day.ts

@@ -13,38 +13,30 @@ import { wallClockInTz } from "./wall-clock";
 /**
  * Get the start (midnight) and end (23:59:59.999) of "today" in the user's
  * timezone, returned as UTC Date objects suitable for database queries.
+ *
+ * DST-safe. Both bounds route through {@link startOfLocalDayInTz}, whose
+ * two-pass solver settles the zone offset AT the target local midnight —
+ * not at `now`. The window therefore spans the user's real local day even
+ * when it is 23 h (spring-forward) or 25 h (fall-back): the previous
+ * implementation sampled the offset at `now` and hardcoded a 24 h length,
+ * so on a fall-back day the last local hour (e.g. a 23:30 dose) fell
+ * OUTSIDE `[midnight, midnight+24h)` and on a spring-forward day the window
+ * bled one hour into the next local day.
  */
 export function getUserTodayBounds(
   now: Date,
   tz: string,
 ): { start: Date; end: Date } {
-  const parts = wallClockInTz(now, tz);
-
-  // Build a UTC date that represents the user's local midnight
-  // by computing the offset between the real UTC time and the local
-  // representation.
-  const localMidnightAsUtc = new Date(
-    Date.UTC(parts.year, parts.month - 1, parts.day, 0, 0, 0, 0),
+  const start = startOfLocalDayInTz(now, tz);
+  // Start of the NEXT local day. Advancing 25 h always crosses into the next
+  // calendar day (a real day is 23–25 h, never ≤ 12.5 h, so 25 h can neither
+  // fall short of the next day nor skip past it), then floor back to that
+  // day's local midnight. `end` is the inclusive last millisecond of today.
+  const nextDayStart = startOfLocalDayInTz(
+    new Date(start.getTime() + 25 * 60 * 60 * 1000),
+    tz,
   );
-
-  // Compute offset: how far ahead (positive) or behind (negative) the tz is
-  // from UTC. localMidnightAsUtc represents "midnight in tz as if it were
-  // UTC"; we need the UTC instant that corresponds to midnight in the tz.
-  const localNowAsUtc = new Date(
-    Date.UTC(
-      parts.year,
-      parts.month - 1,
-      parts.day,
-      parts.hour,
-      parts.minute,
-      parts.second,
-    ),
-  );
-  const offsetMs =
-    Math.round((localNowAsUtc.getTime() - now.getTime()) / 60000) * 60000;
-
-  const start = new Date(localMidnightAsUtc.getTime() - offsetMs);
-  const end = new Date(start.getTime() + 24 * 60 * 60 * 1000 - 1);
+  const end = new Date(nextDayStart.getTime() - 1);
 
   return { start, end };
 }

src/lib/tz/resolver.ts

@@ -48,6 +48,7 @@ export {
   detectBrowserTimezone,
   formatInUserTz,
   userDayKey,
+  hourInTz,
   type FormatInUserTzShape,
 } from "./format";