diff --git a/prisma/migrations/0079_v1449_user_notification_prefs/migration.sql b/prisma/migrations/0079_v1449_user_notification_prefs/migration.sql
new file mode 100644
index 000000000..26961682e
--- /dev/null
+++ b/prisma/migrations/0079_v1449_user_notification_prefs/migration.sql
@@ -0,0 +1,41 @@
+-- v1.4.49 M-DOUBLE-REMINDER — per-user notification preferences blob.
+--
+-- iOS v0.6.0.7 wires local SpeziScheduler banners for medication doses.
+-- Once the client has confirmed (a) APNs permission = `.authorized`,
+-- (b) Spezi reminders are actively scheduled, and (c) the binary is
+-- >= v0.6.0.7, it flips `notification_prefs.medication.clientManaged`
+-- to true via `PATCH /api/auth/me/notification-prefs`. The server-side
+-- MEDICATION_REMINDER cron then suppresses the redundant APNs push for
+-- that user so the dose only buzzes once.
+--
+-- Shape (additive — future categories slot in next to `medication`):
+--   {
+--     "medication": { "clientManaged": boolean }
+--   }
+--
+-- Default `NULL` (the column itself), which the application layer
+-- resolves to `{ medication: { clientManaged: false } }` so every
+-- existing user keeps the legacy server-side push until the iOS app
+-- explicitly opts them in. This preserves UX for clients that don't
+-- have working local reminders yet (e.g. the
+-- `healthlog-iOS#10` notification-permission-stuck-`notDetermined`
+-- scenario).
+--
+-- Idempotent guard (`IF NOT EXISTS`) matches the 0067 / 0070 / 0071 /
+-- 0075 / 0078 pattern so reruns are safe on prod where the migration
+-- has already been applied.
+--
+-- Reversibility: down migration is
+--   ALTER TABLE "users" DROP COLUMN IF EXISTS "notification_prefs";
+-- A roll-back loses opt-in state for every user that had flipped
+-- `clientManaged` (they fall back to server-side reminders) but the
+-- application reads tolerate a missing column / null row and default
+-- to `clientManaged: false`, so a partial deploy where the schema is
+-- rolled back ahead of the app code keeps working.
+
+-- No additional index — reads at cron time are per-user
+-- (`WHERE id = $1`), matching the convention set by
+-- `source_priority_json` and `doctor_report_prefs_json` on the same
+-- table (no GIN index on either).
+ALTER TABLE "users"
+    ADD COLUMN IF NOT EXISTS "notification_prefs" JSONB;
diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index c40f16d52..52ca861bc 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -223,6 +223,30 @@ model User {
   // payload when the toggle is off so the data never leaves the DB row.
   doctorReportPrefsJson Json? @map("doctor_report_prefs_json")
 
+  // v1.4.49 M-DOUBLE-REMINDER — per-user notification preferences blob.
+  //
+  // Opt-in suppression for redundant server-side pushes. Shape:
+  //   { "medication": { "clientManaged": boolean } }
+  //
+  // When `medication.clientManaged === true`, the reminder cron skips
+  // the APNs `MEDICATION_REMINDER` for this user — iOS v0.6.0.7+
+  // schedules local SpeziScheduler banners that cover the same dose.
+  // The iOS app flips the flag to true on first launch after it has
+  // confirmed (a) APNs permission = `.authorized`, (b) local Spezi
+  // reminders are actively scheduled, and (c) the binary is
+  // >= v0.6.0.7. Default `null` (resolved as `clientManaged: false`)
+  // so existing installs see zero regression — server reminders flow
+  // unchanged until the iOS client explicitly opts the user in.
+  //
+  // Only `MEDICATION_REMINDER` is gated by this flag; MOOD_REMINDER,
+  // PERSONAL_RECORD, SYSTEM_ALERT, and anomaly pushes flow unchanged.
+  //
+  // Persisted via `PATCH /api/auth/me/notification-prefs` with
+  // deep-merge semantics so future categories (e.g. mood,
+  // personal_records) slot in next to `medication` without
+  // overwriting siblings.
+  notificationPrefs Json? @map("notification_prefs")
+
   // v1.4.47 W3 — per-user Coach opt-out (privacy-leaning users).
   //
   // When `true`, every Coach mount point on the web client renders
diff --git a/src/app/api/auth/me/notification-prefs/__tests__/route.test.ts b/src/app/api/auth/me/notification-prefs/__tests__/route.test.ts
new file mode 100644
index 000000000..c16c9d6b4
--- /dev/null
+++ b/src/app/api/auth/me/notification-prefs/__tests__/route.test.ts
@@ -0,0 +1,270 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("@/lib/db", () => ({
+  prisma: {
+    user: {
+      findUnique: vi.fn(),
+      update: vi.fn(),
+    },
+  },
+  toJson: <T,>(v: T) => v,
+}));
+
+vi.mock("@/lib/auth/session", () => ({ getSession: vi.fn() }));
+
+vi.mock("@/lib/auth/audit", () => ({
+  auditLog: vi.fn().mockResolvedValue(undefined),
+}));
+
+vi.mock("@/lib/logging/transports", () => ({ emitIfSampled: vi.fn() }));
+
+vi.mock("@/lib/db-compat", () => ({
+  ensureDbCompatibility: vi.fn().mockResolvedValue(undefined),
+}));
+
+vi.mock("@/lib/rate-limit", () => ({
+  checkRateLimit: vi.fn().mockResolvedValue({
+    allowed: true,
+    remaining: 59,
+    resetAt: Date.now() + 60_000,
+  }),
+  rateLimitHeaders: () => ({}),
+}));
+
+vi.mock("next/headers", () => ({
+  headers: vi.fn(async () => ({ get: () => null })),
+  cookies: vi.fn(async () => ({
+    get: () => undefined,
+    set: () => {},
+    delete: () => {},
+  })),
+}));
+
+import { GET, PATCH } from "../route";
+import { prisma } from "@/lib/db";
+import { getSession } from "@/lib/auth/session";
+import { auditLog } from "@/lib/auth/audit";
+import { checkRateLimit } from "@/lib/rate-limit";
+
+const SESSION_OK = {
+  session: { id: "sess-1", expiresAt: new Date(Date.now() + 3_600_000) },
+  user: { id: "user-1", username: "marc", role: "USER" as const },
+};
+
+function mkPatch(body: unknown): Request {
+  return new Request("http://localhost/api/auth/me/notification-prefs", {
+    method: "PATCH",
+    body: JSON.stringify(body),
+    headers: { "Content-Type": "application/json" },
+  });
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+});
+
+describe("GET /api/auth/me/notification-prefs", () => {
+  it("rejects an unauthenticated request with 401", async () => {
+    vi.mocked(getSession).mockResolvedValue(null);
+
+    const res = await (GET as (r: Request) => Promise<Response>)(
+      new Request("http://localhost/api/auth/me/notification-prefs"),
+    );
+    expect(res.status).toBe(401);
+    expect(prisma.user.findUnique).not.toHaveBeenCalled();
+  });
+
+  it("returns the documented defaults for a fresh user (null row)", async () => {
+    vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
+    vi.mocked(prisma.user.findUnique).mockResolvedValue({
+      notificationPrefs: null,
+    } as never);
+
+    const res = await (GET as (r: Request) => Promise<Response>)(
+      new Request("http://localhost/api/auth/me/notification-prefs"),
+    );
+    expect(res.status).toBe(200);
+    const env = (await res.json()) as {
+      data: { medication: { clientManaged: boolean } };
+    };
+    expect(env.data).toEqual({ medication: { clientManaged: false } });
+  });
+
+  it("returns the resolved prefs when the row holds a value", async () => {
+    vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
+    vi.mocked(prisma.user.findUnique).mockResolvedValue({
+      notificationPrefs: { medication: { clientManaged: true } },
+    } as never);
+
+    const res = await (GET as (r: Request) => Promise<Response>)(
+      new Request("http://localhost/api/auth/me/notification-prefs"),
+    );
+    expect(res.status).toBe(200);
+    const env = (await res.json()) as {
+      data: { medication: { clientManaged: boolean } };
+    };
+    expect(env.data).toEqual({ medication: { clientManaged: true } });
+  });
+
+  it("returns defaults when the persisted shape has drifted", async () => {
+    // Forward-compat: an admin hand-edit / future-rename should not
+    // crash the GET.
+    vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
+    vi.mocked(prisma.user.findUnique).mockResolvedValue({
+      notificationPrefs: { unknownCategory: { foo: "bar" } },
+    } as never);
+
+    const res = await (GET as (r: Request) => Promise<Response>)(
+      new Request("http://localhost/api/auth/me/notification-prefs"),
+    );
+    expect(res.status).toBe(200);
+    const env = (await res.json()) as {
+      data: { medication: { clientManaged: boolean } };
+    };
+    expect(env.data).toEqual({ medication: { clientManaged: false } });
+  });
+});
+
+describe("PATCH /api/auth/me/notification-prefs", () => {
+  it("rejects an unauthenticated request with 401", async () => {
+    vi.mocked(getSession).mockResolvedValue(null);
+
+    const res = await (PATCH as (r: Request) => Promise<Response>)(
+      mkPatch({ medication: { clientManaged: true } }),
+    );
+    expect(res.status).toBe(401);
+    expect(prisma.user.update).not.toHaveBeenCalled();
+  });
+
+  it("flips medication.clientManaged on and writes the audit row", async () => {
+    vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
+    vi.mocked(prisma.user.findUnique).mockResolvedValue({
+      notificationPrefs: null,
+    } as never);
+    vi.mocked(prisma.user.update).mockResolvedValue({} as never);
+
+    const res = await (PATCH as (r: Request) => Promise<Response>)(
+      mkPatch({ medication: { clientManaged: true } }),
+    );
+    expect(res.status).toBe(200);
+    const env = (await res.json()) as {
+      data: { medication: { clientManaged: boolean } };
+    };
+    expect(env.data).toEqual({ medication: { clientManaged: true } });
+
+    expect(prisma.user.update).toHaveBeenCalledWith({
+      where: { id: "user-1" },
+      data: {
+        notificationPrefs: { medication: { clientManaged: true } },
+      },
+    });
+
+    expect(auditLog).toHaveBeenCalledWith(
+      "user.notification-prefs.update",
+      expect.objectContaining({
+        userId: "user-1",
+        details: expect.objectContaining({
+          previous: { medication: { clientManaged: false } },
+          next: { medication: { clientManaged: true } },
+          changed: ["medication"],
+        }),
+      }),
+    );
+  });
+
+  it("rejects malformed JSON with 422", async () => {
+    vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
+
+    const req = new Request(
+      "http://localhost/api/auth/me/notification-prefs",
+      {
+        method: "PATCH",
+        body: "{ not valid json",
+        headers: { "Content-Type": "application/json" },
+      },
+    );
+
+    const res = await (PATCH as (r: Request) => Promise<Response>)(req);
+    expect(res.status).toBe(422);
+    expect(prisma.user.update).not.toHaveBeenCalled();
+  });
+
+  it("rejects a non-boolean clientManaged with 422", async () => {
+    vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
+
+    const res = await (PATCH as (r: Request) => Promise<Response>)(
+      mkPatch({ medication: { clientManaged: "yes" } }),
+    );
+    expect(res.status).toBe(422);
+    expect(prisma.user.update).not.toHaveBeenCalled();
+  });
+
+  it("deep-merges over existing siblings without overwriting them", async () => {
+    // Forward-compat: a row that already carries an unknown sibling
+    // category (e.g. a future "mood" key persisted by a newer client)
+    // must survive a PATCH that only touches `medication`. The route
+    // parses with the current zod schema first, then deep-merges the
+    // input over the parsed (defaulted) base. Today, "unknown sibling"
+    // resolves back to defaults; the test pins that the medication
+    // PATCH still lands and that future schema growth (adding new
+    // siblings to the zod shape) will preserve them.
+    vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
+    vi.mocked(prisma.user.findUnique).mockResolvedValue({
+      notificationPrefs: { medication: { clientManaged: false } },
+    } as never);
+    vi.mocked(prisma.user.update).mockResolvedValue({} as never);
+
+    const res = await (PATCH as (r: Request) => Promise<Response>)(
+      mkPatch({ medication: { clientManaged: true } }),
+    );
+    expect(res.status).toBe(200);
+
+    expect(prisma.user.update).toHaveBeenCalledWith({
+      where: { id: "user-1" },
+      data: {
+        notificationPrefs: { medication: { clientManaged: true } },
+      },
+    });
+  });
+
+  it("returns the merged shape unchanged on an empty PATCH body", async () => {
+    // Idempotent — an empty body keeps the row as-is and still writes
+    // the audit trail (mirrors the disable-coach posture).
+    vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
+    vi.mocked(prisma.user.findUnique).mockResolvedValue({
+      notificationPrefs: { medication: { clientManaged: true } },
+    } as never);
+    vi.mocked(prisma.user.update).mockResolvedValue({} as never);
+
+    const res = await (PATCH as (r: Request) => Promise<Response>)(
+      mkPatch({}),
+    );
+    expect(res.status).toBe(200);
+    const env = (await res.json()) as {
+      data: { medication: { clientManaged: boolean } };
+    };
+    expect(env.data).toEqual({ medication: { clientManaged: true } });
+
+    expect(prisma.user.update).toHaveBeenCalledWith({
+      where: { id: "user-1" },
+      data: {
+        notificationPrefs: { medication: { clientManaged: true } },
+      },
+    });
+  });
+
+  it("returns 429 when the per-user rate-limit fires", async () => {
+    vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
+    vi.mocked(checkRateLimit).mockResolvedValueOnce({
+      allowed: false,
+      remaining: 0,
+      resetAt: Date.now() + 30_000,
+    });
+
+    const res = await (PATCH as (r: Request) => Promise<Response>)(
+      mkPatch({ medication: { clientManaged: true } }),
+    );
+    expect(res.status).toBe(429);
+    expect(prisma.user.update).not.toHaveBeenCalled();
+  });
+});
diff --git a/src/app/api/auth/me/notification-prefs/route.ts b/src/app/api/auth/me/notification-prefs/route.ts
new file mode 100644
index 000000000..f22c1b1f6
--- /dev/null
+++ b/src/app/api/auth/me/notification-prefs/route.ts
@@ -0,0 +1,133 @@
+/**
+ * v1.4.49 M-DOUBLE-REMINDER — per-user notification preferences endpoint.
+ *
+ *  GET    /api/auth/me/notification-prefs  — current resolved prefs.
+ *  PATCH  /api/auth/me/notification-prefs  — body `{ medication?: { clientManaged?: boolean } }`.
+ *                                            Deep-merges the supplied
+ *                                            shape over the persisted
+ *                                            row so future categories
+ *                                            slot in next to
+ *                                            `medication` without
+ *                                            overwriting siblings.
+ *
+ * Auth is shared via `requireAuth()` so cookie sessions + Bearer
+ * tokens both work (the iOS app uses Bearer). Default shape lives in
+ * `parseNotificationPrefs` — a null DB row resolves to
+ * `{ medication: { clientManaged: false } }`, preserving the legacy
+ * server-side reminder behaviour for any user the iOS client has not
+ * yet opted in.
+ *
+ * Idempotent. The endpoint always returns the fully-resolved next
+ * state so the client can hard-set the optimistic update without an
+ * extra round-trip. Rate-limit is intentionally generous (60/min) —
+ * matches the disable-coach route which is the closest analogue.
+ */
+import { apiHandler, requireAuth, HttpError } from "@/lib/api-handler";
+import {
+  apiError,
+  apiSuccess,
+  getClientIp,
+  returnAllZodIssues,
+} from "@/lib/api-response";
+import { annotate } from "@/lib/logging/context";
+import { auditLog } from "@/lib/auth/audit";
+import { prisma, toJson } from "@/lib/db";
+import { checkRateLimit, rateLimitHeaders } from "@/lib/rate-limit";
+import {
+  notificationPrefsSchema,
+  parseNotificationPrefs,
+  resolveNotificationPrefs,
+} from "@/lib/validations/notification-prefs";
+
+export const dynamic = "force-dynamic";
+
+const PATCH_RATE_LIMIT = 60;
+const PATCH_WINDOW_MS = 60_000;
+
+export const GET = apiHandler(async () => {
+  const { user } = await requireAuth();
+  annotate({ action: { name: "auth.me.notification-prefs.get" } });
+
+  const row = await prisma.user.findUnique({
+    where: { id: user.id },
+    select: { notificationPrefs: true },
+  });
+  return apiSuccess(parseNotificationPrefs(row?.notificationPrefs ?? null));
+});
+
+export const PATCH = apiHandler(async (req: Request) => {
+  const { user } = await requireAuth();
+
+  const rl = await checkRateLimit(
+    `notification-prefs:patch:${user.id}`,
+    PATCH_RATE_LIMIT,
+    PATCH_WINDOW_MS,
+  );
+  if (!rl.allowed) {
+    const response = apiError("Too many requests", 429);
+    for (const [k, v] of Object.entries(rateLimitHeaders(rl))) {
+      response.headers.set(k, v);
+    }
+    return response;
+  }
+
+  let body: unknown;
+  try {
+    body = await req.json();
+  } catch {
+    throw new HttpError(422, "notification-prefs.body.invalid_json");
+  }
+
+  const parsed = notificationPrefsSchema.safeParse(body ?? {});
+  if (!parsed.success) {
+    annotate({
+      action: { name: "auth.me.notification-prefs.patch.invalid_shape" },
+      meta: { issues: parsed.error.issues.length },
+    });
+    return returnAllZodIssues(parsed.error, 422);
+  }
+
+  // Deep-merge the partial input over the current row so a PATCH that
+  // only touches `medication` does not overwrite future sibling
+  // categories (mood, personal_records, ...). The full resolved shape
+  // is persisted so the column layout stays stable across schema
+  // additions.
+  const current = await prisma.user.findUnique({
+    where: { id: user.id },
+    select: { notificationPrefs: true },
+  });
+  const previous = parseNotificationPrefs(current?.notificationPrefs ?? null);
+  const merged = resolveNotificationPrefs(
+    current?.notificationPrefs ?? null,
+    parsed.data,
+  );
+
+  await prisma.user.update({
+    where: { id: user.id },
+    data: { notificationPrefs: toJson(merged) },
+  });
+
+  // Capture which categories the PATCH actually touched so the audit
+  // trail records the user's intent, not just the full resolved row.
+  const changedCategories = Object.keys(parsed.data);
+
+  await auditLog("user.notification-prefs.update", {
+    userId: user.id,
+    ipAddress: getClientIp(req),
+    details: {
+      previous,
+      next: merged,
+      changed: changedCategories,
+    },
+  });
+
+  annotate({
+    action: { name: "user.notification_prefs.update" },
+    meta: {
+      changed: changedCategories,
+      medication_client_managed: merged.medication.clientManaged,
+    },
+  });
+
+  return apiSuccess(merged);
+});
diff --git a/src/lib/jobs/reminder-worker.ts b/src/lib/jobs/reminder-worker.ts
index e61b6d35d..9d8f9a16e 100644
--- a/src/lib/jobs/reminder-worker.ts
+++ b/src/lib/jobs/reminder-worker.ts
@@ -110,6 +110,7 @@ import {
   getPhaseKeyboard,
 } from "@/lib/jobs/reminder-phases";
 import { runMoodReminderTick } from "@/lib/jobs/mood-reminder";
+import { isMedicationReminderClientManaged } from "@/lib/validations/notification-prefs";
 import { withBackgroundEvent } from "@/lib/logging/background";
 import { assertSubsystemEnabled } from "@/lib/process-type";
 import { runOffhostBackup } from "@/lib/jobs/offhost-backup";
@@ -459,6 +460,12 @@ async function handleReminderCheck(jobs: Job<ReminderCheckPayload>[]) {
               // Used to localise the reminder title / message / keyboard
               // labels per user. Null falls back to the app default.
               locale: true,
+              // v1.4.49 M-DOUBLE-REMINDER — read the per-user prefs
+              // blob so the dispatch step can skip APNs sends for users
+              // whose iOS client has opted in to local SpeziScheduler
+              // reminders. Null = legacy default (clientManaged: false),
+              // i.e. the server reminder fires as before.
+              notificationPrefs: true,
             },
           },
         },
@@ -623,6 +630,42 @@ async function handleReminderCheck(jobs: Job<ReminderCheckPayload>[]) {
 
           // Send notification if enabled
           if (med.notificationsEnabled) {
+            // v1.4.49 M-DOUBLE-REMINDER — opt-in client-managed
+            // suppression. When the iOS app has confirmed local
+            // SpeziScheduler banners cover the dose, the server-side
+            // APNs push is redundant. Skip the dispatch and emit a
+            // wide-event annotation so the operator can audit the
+            // skip path. ONLY suppresses MEDICATION_REMINDER — other
+            // notification kinds (MOOD_REMINDER, PERSONAL_RECORD,
+            // SYSTEM_ALERT, anomaly alerts) flow unchanged.
+            if (
+              isMedicationReminderClientManaged(med.user.notificationPrefs)
+            ) {
+              const [winH, winM] = schedule.windowStart.split(":").map(Number);
+              const doseAtIso = localHmAsUtc(
+                now,
+                med.user.timezone,
+                winH,
+                winM,
+              ).toISOString();
+              evt.addMeta(
+                "medication_reminder_suppressed_client_managed",
+                `${med.name}:${schedule.windowStart}-${schedule.windowEnd}`,
+              );
+              evt.addMeta(
+                "medication_reminder_suppressed_meta",
+                {
+                  user_id: med.user.id,
+                  medication_id: med.id,
+                  schedule_id: schedule.id,
+                  phase: currentPhase,
+                  dose_at: doseAtIso,
+                },
+              );
+              schedulesProcessed++;
+              continue;
+            }
+
             const { title, message } = getPhaseMessage(
               currentPhase,
               med.name,
diff --git a/src/lib/validations/__tests__/notification-prefs.test.ts b/src/lib/validations/__tests__/notification-prefs.test.ts
new file mode 100644
index 000000000..2b45a6c46
--- /dev/null
+++ b/src/lib/validations/__tests__/notification-prefs.test.ts
@@ -0,0 +1,146 @@
+import { describe, expect, it } from "vitest";
+
+import {
+  DEFAULT_NOTIFICATION_PREFS,
+  isMedicationReminderClientManaged,
+  notificationPrefsSchema,
+  parseNotificationPrefs,
+  resolveNotificationPrefs,
+} from "../notification-prefs";
+
+/**
+ * v1.4.49 M-DOUBLE-REMINDER — per-user notification preferences blob.
+ *
+ * The cron at `src/lib/jobs/reminder-worker.ts` reads
+ * `user.notificationPrefs` and calls
+ * `isMedicationReminderClientManaged` to decide whether to skip the
+ * MEDICATION_REMINDER APNs dispatch. These tests pin the helper's
+ * contract so the cron skip is deterministic across schema drift.
+ */
+describe("notificationPrefsSchema", () => {
+  it("accepts an empty object (every key is optional)", () => {
+    const out = notificationPrefsSchema.parse({});
+    expect(out).toEqual({});
+  });
+
+  it("accepts the medication.clientManaged shape", () => {
+    const input = { medication: { clientManaged: true } };
+    const out = notificationPrefsSchema.parse(input);
+    expect(out).toEqual(input);
+  });
+
+  it("rejects a non-boolean clientManaged", () => {
+    const res = notificationPrefsSchema.safeParse({
+      medication: { clientManaged: "yes" },
+    });
+    expect(res.success).toBe(false);
+  });
+});
+
+describe("parseNotificationPrefs", () => {
+  it("returns documented defaults for null", () => {
+    expect(parseNotificationPrefs(null)).toEqual(DEFAULT_NOTIFICATION_PREFS);
+  });
+
+  it("returns documented defaults for undefined", () => {
+    expect(parseNotificationPrefs(undefined)).toEqual(
+      DEFAULT_NOTIFICATION_PREFS,
+    );
+  });
+
+  it("returns defaults when the persisted shape has drifted", () => {
+    expect(parseNotificationPrefs({ unknown: "shape" })).toEqual(
+      DEFAULT_NOTIFICATION_PREFS,
+    );
+  });
+
+  it("returns the persisted shape when valid", () => {
+    expect(
+      parseNotificationPrefs({ medication: { clientManaged: true } }),
+    ).toEqual({ medication: { clientManaged: true } });
+  });
+
+  it("fills missing keys from the defaults", () => {
+    expect(parseNotificationPrefs({ medication: {} })).toEqual({
+      medication: { clientManaged: false },
+    });
+  });
+});
+
+describe("resolveNotificationPrefs (deep-merge)", () => {
+  it("layers the input over the persisted row", () => {
+    const out = resolveNotificationPrefs(
+      { medication: { clientManaged: false } },
+      { medication: { clientManaged: true } },
+    );
+    expect(out).toEqual({ medication: { clientManaged: true } });
+  });
+
+  it("preserves the persisted medication keys when the input only touches new sub-keys", () => {
+    // Future-proof: the route hands the merged shape to Prisma, so
+    // sibling keys inside `medication` must survive a partial PATCH.
+    const out = resolveNotificationPrefs(
+      { medication: { clientManaged: true } },
+      { medication: {} },
+    );
+    expect(out).toEqual({ medication: { clientManaged: true } });
+  });
+
+  it("falls back to defaults when the persisted row is null", () => {
+    const out = resolveNotificationPrefs(null, {
+      medication: { clientManaged: true },
+    });
+    expect(out).toEqual({ medication: { clientManaged: true } });
+  });
+
+  it("returns the defaults when neither side carries a value", () => {
+    const out = resolveNotificationPrefs(null, {});
+    expect(out).toEqual(DEFAULT_NOTIFICATION_PREFS);
+  });
+});
+
+describe("isMedicationReminderClientManaged — cron-skip gate", () => {
+  it("returns false for a null row (legacy server-managed default)", () => {
+    expect(isMedicationReminderClientManaged(null)).toBe(false);
+  });
+
+  it("returns false for undefined (Prisma findUnique miss)", () => {
+    expect(isMedicationReminderClientManaged(undefined)).toBe(false);
+  });
+
+  it("returns false when the user has not opted in", () => {
+    expect(
+      isMedicationReminderClientManaged({
+        medication: { clientManaged: false },
+      }),
+    ).toBe(false);
+  });
+
+  it("returns true when the user has opted in via the iOS app", () => {
+    expect(
+      isMedicationReminderClientManaged({
+        medication: { clientManaged: true },
+      }),
+    ).toBe(true);
+  });
+
+  it("returns false for a drifted persisted shape (forward-compat)", () => {
+    expect(
+      isMedicationReminderClientManaged({ notACategory: { foo: "bar" } }),
+    ).toBe(false);
+  });
+
+  it("returns false when only sibling categories are present", () => {
+    // Future-proof: another (future) category set to true must NOT
+    // gate MEDICATION_REMINDER — only `medication.clientManaged`
+    // affects the medication cron.
+    expect(
+      isMedicationReminderClientManaged({
+        // Cast through unknown — the production runtime sees this as
+        // a JSONB value that bypasses the zod schema, but the helper
+        // must still resolve to the safe default.
+        otherCategory: { enabled: true },
+      } as unknown),
+    ).toBe(false);
+  });
+});
diff --git a/src/lib/validations/notification-prefs.ts b/src/lib/validations/notification-prefs.ts
new file mode 100644
index 000000000..c10c3ed50
--- /dev/null
+++ b/src/lib/validations/notification-prefs.ts
@@ -0,0 +1,128 @@
+/**
+ * v1.4.49 M-DOUBLE-REMINDER — per-user notification preferences blob.
+ *
+ * Persisted on `User.notificationPrefs` as Postgres jsonb. Null = the
+ * documented defaults (every category off). The flag is opt-in: the
+ * iOS app flips it to `true` only after confirming local Spezi
+ * reminders are wired, so existing users without a working local
+ * notification path see zero regression.
+ *
+ * Shape (additive — future categories slot in next to `medication`):
+ *   {
+ *     "medication": { "clientManaged": boolean }
+ *   }
+ *
+ * The schema is intentionally additive — every new category grows the
+ * schema with a new optional sub-object plus an entry in
+ * `DEFAULT_NOTIFICATION_PREFS`. Forward-compat: an unknown / drifted
+ * shape falls back to defaults rather than throwing.
+ */
+import { z } from "zod/v4";
+
+/**
+ * Medication category schema. Currently a single boolean
+ * (`clientManaged`); the sub-object exists so future per-category
+ * knobs (e.g. quiet-hours overrides) can be added without breaking
+ * the persisted layout.
+ */
+const medicationPrefsSchema = z
+  .object({
+    clientManaged: z.boolean(),
+  })
+  .partial();
+
+/**
+ * Top-level prefs schema. Every category is optional so a PATCH that
+ * only touches `medication` doesn't have to re-state future siblings.
+ * The route layer deep-merges the partial input over the persisted
+ * row before persisting so the column shape stays stable.
+ */
+export const notificationPrefsSchema = z
+  .object({
+    medication: medicationPrefsSchema,
+  })
+  .partial();
+
+export type NotificationPrefsInput = z.infer<typeof notificationPrefsSchema>;
+
+/**
+ * Fully-resolved prefs. Every key required so consumers (cron
+ * suppression, GET response) don't need to thread "is this present?"
+ * checks through their paths.
+ */
+export interface NotificationPrefs {
+  medication: {
+    clientManaged: boolean;
+  };
+}
+
+/**
+ * Safe defaults. Every category is off so the server reminders flow
+ * unchanged for any user the iOS app has not explicitly opted in.
+ * Marc's directive: zero regression for clients without working
+ * local reminders.
+ */
+export const DEFAULT_NOTIFICATION_PREFS: NotificationPrefs = {
+  medication: {
+    clientManaged: false,
+  },
+};
+
+/**
+ * Parse the persisted `notificationPrefs` JSON blob into a typed
+ * `NotificationPrefs`, falling back to the defaults when the row is
+ * null OR the persisted shape has drifted (a forward-compat field
+ * rename, an admin-side hand-edit, etc.). Missing keys are filled
+ * from the defaults so callers always get a fully-resolved object.
+ */
+export function parseNotificationPrefs(raw: unknown): NotificationPrefs {
+  if (raw == null) return cloneDefaults();
+  const parsed = notificationPrefsSchema.safeParse(raw);
+  if (!parsed.success) return cloneDefaults();
+  return mergeOverDefaults(parsed.data);
+}
+
+/**
+ * Deep-merge a partial input (typically from a PATCH body) over the
+ * current persisted row, layering each supplied category's keys over
+ * the existing category sub-object so future siblings are not
+ * overwritten when the client only PATCHes `medication`.
+ */
+export function resolveNotificationPrefs(
+  current: unknown,
+  incoming: NotificationPrefsInput,
+): NotificationPrefs {
+  const base = parseNotificationPrefs(current);
+  return {
+    medication: {
+      ...base.medication,
+      ...(incoming.medication ?? {}),
+    },
+  };
+}
+
+/**
+ * Cron-side helper. Returns `true` when the user has opted in to
+ * client-managed medication reminders and the server-side push
+ * should be suppressed. Tolerates a null / missing prefs row.
+ */
+export function isMedicationReminderClientManaged(raw: unknown): boolean {
+  return parseNotificationPrefs(raw).medication.clientManaged === true;
+}
+
+function cloneDefaults(): NotificationPrefs {
+  return {
+    medication: { ...DEFAULT_NOTIFICATION_PREFS.medication },
+  };
+}
+
+function mergeOverDefaults(
+  input: NotificationPrefsInput,
+): NotificationPrefs {
+  return {
+    medication: {
+      ...DEFAULT_NOTIFICATION_PREFS.medication,
+      ...(input.medication ?? {}),
+    },
+  };
+}