diff --git a/src/lib/withings/__tests__/sync-activity.test.ts b/src/lib/withings/__tests__/sync-activity.test.ts
index 5a2dcc55f..691de676f 100644
--- a/src/lib/withings/__tests__/sync-activity.test.ts
+++ b/src/lib/withings/__tests__/sync-activity.test.ts
@@ -45,7 +45,7 @@ vi.mock("@/lib/logging/context", () => ({
 }));
 
 import { prisma } from "@/lib/db";
-import { recordSyncSuccess } from "@/lib/integrations/status";
+import { recordSyncFailure, recordSyncSuccess } from "@/lib/integrations/status";
 
 import { fetchWithingsActivity, syncUserActivity } from "../sync-activity";
 
@@ -74,6 +74,14 @@ function installFetchMock(entries: FakeActivity[]) {
 
 beforeEach(() => {
   vi.resetAllMocks();
+  // v1.4.26 — every syncUserActivity call now reads the connection's
+  // scope to short-circuit legacy `user.metrics`-only connections.
+  // Default-mock to "scope is fine" so the existing field-mapping +
+  // idempotency tests stay focused on the write path. The scope-skip
+  // case has its own dedicated tests below.
+  vi.mocked(prisma.withingsConnection.findUnique).mockResolvedValue({
+    scope: "user.metrics,user.activity",
+  } as never);
 });
 
 afterEach(() => {
@@ -255,3 +263,88 @@ describe("syncUserActivity — field mapping + idempotency", () => {
     );
   });
 });
+
+describe("syncUserActivity — scope-skip guard (v1.4.26)", () => {
+  it("returns 0 without firing the Withings call when scope lacks user.activity", async () => {
+    // Legacy v1.4.24- connection — scope holds `user.metrics` only.
+    // The sync must short-circuit BEFORE the upstream fetch so a
+    // guaranteed 403 doesn't park as `transient` and spam pg-boss
+    // retries.
+    vi.mocked(prisma.withingsConnection.findUnique).mockResolvedValue({
+      scope: "user.metrics",
+    } as never);
+    const fetchMock = vi.fn();
+    vi.stubGlobal("fetch", fetchMock);
+
+    const imported = await syncUserActivity("user-1");
+
+    expect(imported).toBe(0);
+    expect(fetchMock).not.toHaveBeenCalled();
+    expect(prisma.measurement.create).not.toHaveBeenCalled();
+    expect(recordSyncSuccess).not.toHaveBeenCalled();
+  });
+
+  it("parks the connection at error_reauth with kind=reauth_required + errorCode=scope_missing", async () => {
+    vi.mocked(prisma.withingsConnection.findUnique).mockResolvedValue({
+      scope: "user.metrics",
+    } as never);
+    vi.stubGlobal("fetch", vi.fn());
+
+    await syncUserActivity("user-1");
+
+    expect(recordSyncFailure).toHaveBeenCalledTimes(1);
+    expect(recordSyncFailure).toHaveBeenCalledWith(
+      expect.objectContaining({
+        userId: "user-1",
+        integration: "withings",
+        kind: "reauth_required",
+        errorCode: "scope_missing",
+      }),
+    );
+  });
+
+  it("treats a null scope (pre-v1.4.25 connection) as missing user.activity", async () => {
+    vi.mocked(prisma.withingsConnection.findUnique).mockResolvedValue({
+      scope: null,
+    } as never);
+    const fetchMock = vi.fn();
+    vi.stubGlobal("fetch", fetchMock);
+
+    const imported = await syncUserActivity("user-1");
+
+    expect(imported).toBe(0);
+    expect(fetchMock).not.toHaveBeenCalled();
+    expect(recordSyncFailure).toHaveBeenCalledWith(
+      expect.objectContaining({ kind: "reauth_required" }),
+    );
+  });
+
+  it("classifies a Withings 403 in the catch-block as reauth_required (defence-in-depth)", async () => {
+    // The scope-skip above is the primary guard. This test covers the
+    // race where Withings revokes scope between OAuth and the next
+    // sync without invalidating the refresh token — `getValidToken`
+    // succeeds, the connection scope still claims `user.activity`,
+    // but the resource call 403s. Must park at reauth_required, not
+    // transient, so pg-boss stops retrying.
+    vi.mocked(prisma.withingsConnection.findUnique).mockResolvedValue({
+      scope: "user.metrics,user.activity",
+    } as never);
+    vi.stubGlobal(
+      "fetch",
+      vi.fn(async () => ({
+        status: 200,
+        json: async () => ({ status: 403, error: "insufficient scope" }),
+      })),
+    );
+
+    await expect(syncUserActivity("user-1")).rejects.toThrow(
+      /Withings activity error: 403/,
+    );
+    expect(recordSyncFailure).toHaveBeenCalledWith(
+      expect.objectContaining({
+        kind: "reauth_required",
+        errorCode: "403",
+      }),
+    );
+  });
+});
diff --git a/src/lib/withings/__tests__/sync-sleep.test.ts b/src/lib/withings/__tests__/sync-sleep.test.ts
index 9ec91f931..1ec9d1ee0 100644
--- a/src/lib/withings/__tests__/sync-sleep.test.ts
+++ b/src/lib/withings/__tests__/sync-sleep.test.ts
@@ -44,7 +44,7 @@ vi.mock("@/lib/logging/context", () => ({
 }));
 
 import { prisma } from "@/lib/db";
-import { recordSyncSuccess } from "@/lib/integrations/status";
+import { recordSyncFailure, recordSyncSuccess } from "@/lib/integrations/status";
 
 import {
   fetchWithingsSleep,
@@ -73,6 +73,14 @@ function installFetchMock(segments: FakeSegment[]) {
 
 beforeEach(() => {
   vi.resetAllMocks();
+  // v1.4.26 — every syncUserSleep call now reads the connection's
+  // scope to short-circuit legacy `user.metrics`-only connections.
+  // Default-mock to "scope is fine" so the existing segment-mapping
+  // tests stay focused on the write path. The scope-skip case has
+  // its own dedicated tests below.
+  vi.mocked(prisma.withingsConnection.findUnique).mockResolvedValue({
+    scope: "user.metrics,user.activity",
+  } as never);
 });
 
 afterEach(() => {
@@ -254,3 +262,82 @@ describe("syncUserSleep — segment writes + idempotency", () => {
     expect(stages).not.toContain("REM");
   });
 });
+
+describe("syncUserSleep — scope-skip guard (v1.4.26)", () => {
+  it("returns 0 without firing the Withings call when scope lacks user.activity", async () => {
+    vi.mocked(prisma.withingsConnection.findUnique).mockResolvedValue({
+      scope: "user.metrics",
+    } as never);
+    const fetchMock = vi.fn();
+    vi.stubGlobal("fetch", fetchMock);
+
+    const imported = await syncUserSleep("user-1");
+
+    expect(imported).toBe(0);
+    expect(fetchMock).not.toHaveBeenCalled();
+    expect(prisma.measurement.create).not.toHaveBeenCalled();
+    expect(recordSyncSuccess).not.toHaveBeenCalled();
+  });
+
+  it("parks the connection at error_reauth with kind=reauth_required + errorCode=scope_missing", async () => {
+    vi.mocked(prisma.withingsConnection.findUnique).mockResolvedValue({
+      scope: "user.metrics",
+    } as never);
+    vi.stubGlobal("fetch", vi.fn());
+
+    await syncUserSleep("user-1");
+
+    expect(recordSyncFailure).toHaveBeenCalledTimes(1);
+    expect(recordSyncFailure).toHaveBeenCalledWith(
+      expect.objectContaining({
+        userId: "user-1",
+        integration: "withings",
+        kind: "reauth_required",
+        errorCode: "scope_missing",
+      }),
+    );
+  });
+
+  it("treats a null scope (pre-v1.4.25 connection) as missing user.activity", async () => {
+    vi.mocked(prisma.withingsConnection.findUnique).mockResolvedValue({
+      scope: null,
+    } as never);
+    const fetchMock = vi.fn();
+    vi.stubGlobal("fetch", fetchMock);
+
+    const imported = await syncUserSleep("user-1");
+
+    expect(imported).toBe(0);
+    expect(fetchMock).not.toHaveBeenCalled();
+    expect(recordSyncFailure).toHaveBeenCalledWith(
+      expect.objectContaining({ kind: "reauth_required" }),
+    );
+  });
+
+  it("classifies a Withings 403 in the catch-block as reauth_required (defence-in-depth)", async () => {
+    // Scope claim says we're fine but the resource call 403s — the
+    // race where Withings revokes scope without invalidating the
+    // refresh token. Must park at reauth_required, not transient,
+    // so pg-boss stops retrying.
+    vi.mocked(prisma.withingsConnection.findUnique).mockResolvedValue({
+      scope: "user.metrics,user.activity",
+    } as never);
+    vi.stubGlobal(
+      "fetch",
+      vi.fn(async () => ({
+        status: 200,
+        json: async () => ({ status: 403, error: "insufficient scope" }),
+      })),
+    );
+
+    await expect(syncUserSleep("user-1")).rejects.toThrow(
+      /Withings sleep error: 403/,
+    );
+    expect(recordSyncFailure).toHaveBeenCalledWith(
+      expect.objectContaining({
+        kind: "reauth_required",
+        errorCode: "403",
+      }),
+    );
+  });
+});
diff --git a/src/lib/withings/sync-activity.ts b/src/lib/withings/sync-activity.ts
index 83ba8e599..018eea583 100644
--- a/src/lib/withings/sync-activity.ts
+++ b/src/lib/withings/sync-activity.ts
@@ -39,6 +39,7 @@ import { prisma } from "@/lib/db";
 import { getEvent } from "@/lib/logging/context";
 import { getUnitForType } from "@/lib/validations/measurement";
 
+import { hasActivityScope } from "./client";
 import {
   extractWithingsStatus,
   isWithingsRefreshReauthFailure,
@@ -202,6 +203,40 @@ export async function syncUserActivity(
   const tokenInfo = await getValidToken(userId);
   if (!tokenInfo) return 0;
 
+  // v1.4.26 — scope-skip guard. The W17b activity endpoint is gated on
+  // `user.activity`; legacy v1.4.24-and-earlier connections sit on
+  // `user.metrics` only and Withings returns HTTP 200 / status 403 for
+  // every request. Without this short-circuit the call fires, the
+  // catch-block classifies the 403 as `"transient"` (the refresh-token
+  // worked; only the resource call failed), pg-boss retries, and the
+  // 3-strike alert fires for every legacy user that hasn't reconnected
+  // since W5d. The Settings reconnect-banner is already in place — the
+  // sync just has to stop hammering the endpoint until the user acts.
+  //
+  // Park behaviour: mark the connection `error_reauth` so the next
+  // hourly cron tick also short-circuits via `isReauthRequired` above
+  // (cheap query, no upstream call). `getValidToken` already fetched
+  // the connection row to refresh the access token; we re-read the
+  // `scope` column with a `select` so the call is one indexed lookup.
+  const connection = await prisma.withingsConnection.findUnique({
+    where: { userId },
+    select: { scope: true },
+  });
+  if (!hasActivityScope(connection?.scope ?? null)) {
+    getEvent()?.addWarning(
+      `withings activity sync skipped for ${userId}: missing user.activity scope (legacy connection — reconnect required)`,
+    );
+    await recordSyncFailure({
+      userId,
+      integration: "withings",
+      kind: "reauth_required",
+      message:
+        "Withings connection is missing the user.activity scope. Reconnect Withings in Settings to enable activity sync.",
+      errorCode: "scope_missing",
+    });
+    return 0;
+  }
+
   // 30-day rolling window keeps the call cheap (≤ one page) and
   // self-heals stale rows from a clock skew or a backfill replay.
   // The webhook-driven path narrows naturally to today/yesterday;
@@ -222,14 +257,22 @@ export async function syncUserActivity(
     );
   } catch (err) {
     const message = err instanceof Error ? err.message : String(err);
+    const status = extractWithingsStatus(message);
+    // v1.4.26 defence-in-depth — a 403 from a scope-gated endpoint
+    // always means scope-missing or token-revoked. Park at
+    // `error_reauth` rather than `transient` so pg-boss stops
+    // retrying and the 3-strike alert doesn't fire. The early
+    // scope-skip above covers the common case; this catches the
+    // race where Withings revokes scope between OAuth and the next
+    // sync without invalidating the refresh token.
+    const isReauth =
+      isWithingsRefreshReauthFailure(message) || status === "403";
     await recordSyncFailure({
       userId,
       integration: "withings",
-      kind: isWithingsRefreshReauthFailure(message)
-        ? "reauth_required"
-        : "transient",
+      kind: isReauth ? "reauth_required" : "transient",
       message,
-      errorCode: extractWithingsStatus(message),
+      errorCode: status,
     });
     throw err;
   }
diff --git a/src/lib/withings/sync-sleep.ts b/src/lib/withings/sync-sleep.ts
index 881f4c094..c3c4a8f78 100644
--- a/src/lib/withings/sync-sleep.ts
+++ b/src/lib/withings/sync-sleep.ts
@@ -37,6 +37,7 @@ import { prisma } from "@/lib/db";
 import { getEvent } from "@/lib/logging/context";
 import { getUnitForType } from "@/lib/validations/measurement";
 
+import { hasActivityScope } from "./client";
 import {
   extractWithingsStatus,
   isWithingsRefreshReauthFailure,
@@ -158,6 +159,31 @@ export async function syncUserSleep(
   const tokenInfo = await getValidToken(userId);
   if (!tokenInfo) return 0;
 
+  // v1.4.26 — scope-skip guard. Sleep v2 shares the `user.activity`
+  // scope gate with the activity endpoints; legacy v1.4.24- connections
+  // 403 on every call. Park at `error_reauth` rather than retrying so
+  // pg-boss stops queuing and the 3-strike alert doesn't fire for users
+  // who haven't reconnected since W5d. See `sync-activity.ts` for the
+  // full rationale.
+  const connection = await prisma.withingsConnection.findUnique({
+    where: { userId },
+    select: { scope: true },
+  });
+  if (!hasActivityScope(connection?.scope ?? null)) {
+    getEvent()?.addWarning(
+      `withings sleep sync skipped for ${userId}: missing user.activity scope (legacy connection — reconnect required)`,
+    );
+    await recordSyncFailure({
+      userId,
+      integration: "withings",
+      kind: "reauth_required",
+      message:
+        "Withings connection is missing the user.activity scope. Reconnect Withings in Settings to enable sleep sync.",
+      errorCode: "scope_missing",
+    });
+    return 0;
+  }
+
   void opts.fullSync;
   const now = new Date();
   const start = new Date(
@@ -175,14 +201,17 @@ export async function syncUserSleep(
     );
   } catch (err) {
     const message = err instanceof Error ? err.message : String(err);
+    const status = extractWithingsStatus(message);
+    // v1.4.26 defence-in-depth — see sync-activity.ts. A 403 on a
+    // scope-gated endpoint always means scope-missing or token-revoked.
+    const isReauth =
+      isWithingsRefreshReauthFailure(message) || status === "403";
     await recordSyncFailure({
       userId,
       integration: "withings",
-      kind: isWithingsRefreshReauthFailure(message)
-        ? "reauth_required"
-        : "transient",
+      kind: isReauth ? "reauth_required" : "transient",
       message,
-      errorCode: extractWithingsStatus(message),
+      errorCode: status,
     });
     throw err;
   }