diff --git a/src/lib/jobs/__tests__/measurement-reminder-byhour.test.ts b/src/lib/jobs/__tests__/measurement-reminder-byhour.test.ts
new file mode 100644
index 000000000..511d06ff9
--- /dev/null
+++ b/src/lib/jobs/__tests__/measurement-reminder-byhour.test.ts
@@ -0,0 +1,119 @@
+/**
+ * A multi-hour protocol (`FREQ=DAILY;BYHOUR=7,19`, the morning-and-evening
+ * blood pressure course) must be sent at both hours. The tick used to gate
+ * on `notifyHour` alone and claim one send per local day, so the evening
+ * slot sat due until the next morning and was never sent in the evening.
+ *
+ * Drives the real tick every 15 minutes across two local days in several
+ * zones, with a claim ledger that behaves like the real one (a key claims
+ * once), and a Prisma double whose updates land on the row the next tick
+ * reads.
+ */
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const claimed = vi.hoisted(() => new Set<string>());
+vi.mock("@/lib/notifications/reminder-dedup", async () => {
+  const actual = await vi.importActual<
+    typeof import("@/lib/notifications/reminder-dedup")
+  >("@/lib/notifications/reminder-dedup");
+  return {
+    ...actual,
+    claimNotificationEvent: vi.fn(
+      async (_prisma: unknown, args: { dedupKey: string }) => {
+        if (claimed.has(args.dedupKey)) return false;
+        claimed.add(args.dedupKey);
+        return true;
+      },
+    ),
+  };
+});
+
+import { wallClockInTz, zonedWallClockToUtc } from "@/lib/tz/wall-clock";
+import { computeReminderNextDueAt } from "@/lib/measurement-reminders/scheduling";
+
+import { runMeasurementReminderTick } from "../measurement-reminder";
+
+const ZONES = [
+  "Europe/Berlin",
+  "America/New_York",
+  "America/Los_Angeles",
+  "Asia/Tokyo",
+  "Pacific/Auckland",
+] as const;
+
+beforeEach(() => {
+  claimed.clear();
+});
+
+function at(tz: string, day: number, hour: number, minute = 0): Date {
+  return zonedWallClockToUtc({ year: 2026, month: 9, day, hour, minute }, tz);
+}
+
+describe.each(ZONES)("BYHOUR=7,19 in %s", (tz) => {
+  it("sends at 07:00 and at 19:00 on each day", async () => {
+    const base = {
+      intervalDays: null,
+      rrule: "FREQ=DAILY;BYHOUR=7,19",
+      anchorDate: at(tz, 14, 0),
+      notifyHour: 7,
+      lastSatisfiedAt: null,
+      createdAt: at(tz, 13, 12),
+    };
+    const row: Record<string, unknown> = {
+      id: "r-bp",
+      userId: "u1",
+      origin: "COACH",
+      measurementType: null,
+      label: "BP",
+      location: null,
+      lastSkippedAt: null,
+      lastNotifiedAt: null,
+      enabled: true,
+      endsOn: null,
+      ...base,
+      nextDueAt: computeReminderNextDueAt(base, tz, at(tz, 14, 0)),
+      user: { id: "u1", timezone: tz, locale: "en" },
+    };
+    const prisma = {
+      measurementReminder: {
+        findMany: vi.fn(async () =>
+          (row.nextDueAt as Date | null) === null ? [] : [row],
+        ),
+        update: vi.fn(async ({ data }: { data: Record<string, unknown> }) => {
+          Object.assign(row, data);
+          return row;
+        }),
+        updateMany: vi.fn(async () => ({ count: 0 })),
+      },
+      measurement: { findFirst: vi.fn(async () => null) },
+      labResult: { findFirst: vi.fn(async () => null) },
+    };
+    const sent: string[] = [];
+    const dispatch = vi.fn(async () => ({
+      dispatched: true,
+      channelsAttempted: 1,
+      channelsSucceeded: 1,
+    }));
+
+    for (
+      let t = at(tz, 14, 0).getTime();
+      t < at(tz, 16, 0).getTime();
+      t += 15 * 60_000
+    ) {
+      const now = new Date(t);
+      const before = dispatch.mock.calls.length;
+      await runMeasurementReminderTick(prisma as never, now, {
+        dispatch: dispatch as never,
+        isModuleEnabled: async () => true,
+      });
+      if (dispatch.mock.calls.length > before) {
+        const p = wallClockInTz(now, tz);
+        sent.push(
+          `${p.day} ${String(p.hour).padStart(2, "0")}:${String(p.minute).padStart(2, "0")}`,
+        );
+      }
+    }
+
+    expect(sent).toEqual(["14 07:00", "14 19:00", "15 07:00", "15 19:00"]);
+  });
+});
diff --git a/src/lib/jobs/measurement-reminder.ts b/src/lib/jobs/measurement-reminder.ts
index 93ca3e0a0..407eb9489 100644
--- a/src/lib/jobs/measurement-reminder.ts
+++ b/src/lib/jobs/measurement-reminder.ts
@@ -50,6 +50,7 @@ import { getEvent } from "@/lib/logging/context";
 import { isModuleEnabled } from "@/lib/modules/gate";
 import type { ModuleKey } from "@/lib/modules/registry";
 import {
+  byHourTimesOfDay,
   computeReminderNextDueAt,
   type ReminderScheduleInput,
 } from "@/lib/measurement-reminders/scheduling";
@@ -169,12 +170,51 @@ async function cleanupExpiredCoachReminders(
 }
 
 /**
- * Pure due-predicate: at this instant, is the reminder due AND inside its
- * local notify-hour window?
+ * The local hours a reminder fires at: every `BYHOUR` of its rule (the
+ * twice-daily BP protocol `FREQ=DAILY;BYHOUR=7,19`), else its `notifyHour`.
+ */
+function reminderFireHours(reminder: {
+  notifyHour: number;
+  rrule?: string | null;
+}): number[] {
+  const byHour = byHourTimesOfDay(reminder.rrule ?? null);
+  return byHour
+    ? byHour.map((hhmm) => Number(hhmm.slice(0, 2)))
+    : [reminder.notifyHour];
+}
+
+/**
+ * The local hour the reminder's current slot belongs to: the hour of
+ * `nextDueAt` on the user's clock when that is one of its fire hours, else
+ * `notifyHour` (a slot stamped before the hour was edited, or a test
+ * fixture with no real slot). For a single-hour reminder this is always
+ * `notifyHour`; for `BYHOUR=7,19` the evening slot reads 19, so it is sent
+ * in the evening instead of waiting for the next morning.
+ */
+export function reminderSlotHour(
+  reminder: {
+    nextDueAt: Date | null;
+    notifyHour: number;
+    rrule?: string | null;
+  },
+  timezone: string,
+): number {
+  const hours = reminderFireHours(reminder);
+  if (reminder.nextDueAt !== null && hours.length > 1) {
+    const slotHour = wallClockInTz(reminder.nextDueAt, timezone).hour;
+    if (hours.includes(slotHour)) return slotHour;
+  }
+  return reminder.notifyHour;
+}
+
+/**
+ * Pure due-predicate: at this instant, is the reminder due AND inside the
+ * local hour of its current slot?
  *
  * "Due" = `nextDueAt != null` and `now >= nextDueAt`. The hour gate keeps
  * a reminder that became overdue overnight from firing at 03:00 — it
- * waits for the user's chosen `notifyHour` to come round in their local
+ * waits for its slot's hour (`reminderSlotHour`: the `notifyHour`, or the
+ * matching `BYHOUR` of a multi-hour rule) to come round in the user's
  * timezone. Pulled out so the unit tests can pin the window boundary
  * (08:59 → no, 09:00 → yes, 09:59 → yes, 10:00 → no) without the DB.
  */
@@ -183,6 +223,7 @@ export function evaluateMeasurementReminderDue(
     enabled: boolean;
     nextDueAt: Date | null;
     notifyHour: number;
+    rrule?: string | null;
   },
   timezone: string,
   now: Date,
@@ -190,9 +231,10 @@ export function evaluateMeasurementReminderDue(
   if (!reminder.enabled || reminder.nextDueAt === null) {
     return { fire: false, inHourWindow: false, isDue: false };
   }
+  const tz = timezone || "Europe/Berlin";
   const isDue = now.getTime() >= reminder.nextDueAt.getTime();
-  const parts = wallClockInTz(now, timezone || "Europe/Berlin");
-  const inHourWindow = parts.hour === reminder.notifyHour;
+  const parts = wallClockInTz(now, tz);
+  const inHourWindow = parts.hour === reminderSlotHour(reminder, tz);
   return { fire: isDue && inHourWindow, inHourWindow, isDue };
 }
 
@@ -298,7 +340,8 @@ export async function runMeasurementReminderTick(
         reminder.lastNotifiedAt != null &&
         reminder.nextDueAt !== null &&
         reminder.lastNotifiedAt.getTime() >= reminder.nextDueAt.getTime() &&
-        wallClockInTz(now, timezone).hour !== reminder.notifyHour
+        wallClockInTz(now, timezone).hour !==
+          reminderSlotHour(reminder, timezone)
       ) {
         summary.skippedOutsideWindow += 1;
         continue;
@@ -338,6 +381,7 @@ export async function runMeasurementReminderTick(
           enabled: reminder.enabled,
           nextDueAt: reminder.nextDueAt,
           notifyHour: reminder.notifyHour,
+          rrule: reminder.rrule,
         },
         timezone,
         now,
@@ -409,10 +453,16 @@ export async function runMeasurementReminderTick(
       const localDate = new Date(now).toLocaleDateString("sv-SE", {
         timeZone: timezone,
       });
+      // A multi-hour rule sends more than once a day, so its claim is per
+      // slot hour; a single-hour reminder keeps the per-day key.
+      const slotSuffix =
+        reminderFireHours(reminder).length > 1
+          ? `T${String(reminderSlotHour(reminder, timezone)).padStart(2, "0")}`
+          : "";
       const claimed = await claimNotificationEvent(prisma, {
         recordUserId: reminder.user.id,
         eventType: "MEASUREMENT_REMINDER",
-        dedupKey: `measurement:${reminder.id}:${localDate}`,
+        dedupKey: `measurement:${reminder.id}:${localDate}${slotSuffix}`,
         since: new Date(now.getTime() - REMINDER_DEDUP_LOOKBACK_MS),
       });
       if (!claimed) {