diff --git a/CHANGELOG.md b/CHANGELOG.md
index d9c773c6a..85e4490d5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,41 @@
 
 ## [Unreleased]
 
+## [1.32.23] — 2026-07-24
+
+Sync status now tells the truth for the connected wearables and CGM sources. A
+few paths could report a sync as healthy when it had actually failed, which
+reset the failure streak, hid the reconnect prompt, and let a dead grant get
+retried on every hourly tick. This release closes those gaps so a failed sync
+reads as failed, an interrupted history import is retried instead of marked
+complete, and a couple of sources start pulling data sooner.
+
+- **A dead WHOOP token no longer reports a successful sync.** When the stored
+  grant is revoked, the connection stays parked with its reconnect prompt and
+  the last-synced time stays put, instead of flipping back to connected and
+  hammering the revoked token every hour. This holds on both the manual sync and
+  the hourly background path.
+- **An interrupted WHOOP history import is retried, not marked done.** A
+  full-history backfill that stops partway is no longer stamped complete, so the
+  gap is retried rather than frozen in place. To pull deep history after
+  connecting, run a full sync from Settings. It walks back to 2020.
+- **Withings ECG now syncs on its own schedule.** A watch-only account with no
+  scale previously never had its ECG recordings pulled. An hourly check now
+  brings them in without waiting on a webhook.
+- **Withings activity and sleep write failures now surface.** A failed write no
+  longer reads as a clean sync; it shows up on the integration's status instead
+  of leaving a green state over missing data.
+- **Oura, Polar, and Nightscout sync errors that previously vanished now
+  surface.** A write that fails partway through is recorded on the integration
+  status rather than being silently dropped, and each error is classified and
+  redacted by the source that owns it.
+- **Strava history import starts at connect time.** Deep history begins
+  importing right after you connect instead of waiting for the next server
+  restart.
+- **WHOOP cycle data uses a wider catch-up window.** A day's strain and energy
+  figures that are still being revised are re-fetched for a week, matching the
+  other WHOOP collections, so a late revision is not missed.
+
 ## [1.32.22] — 2026-07-24
 
 The concurrent-edit protection that reached the layout surfaces now covers the
diff --git a/docs/api/openapi.yaml b/docs/api/openapi.yaml
index 9e46f9cf7..b02b00b47 100644
--- a/docs/api/openapi.yaml
+++ b/docs/api/openapi.yaml
@@ -1,7 +1,7 @@
 openapi: 3.1.0
 info:
   title: HealthLog API
-  version: 1.32.22
+  version: 1.32.23
   description: >-
     Self-hosted personal-health-tracking PWA — public API surface for the iOS native client and external ingest.
 
diff --git a/package.json b/package.json
index 65445a089..3dbbb9edd 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "healthlog",
-  "version": "1.32.22",
+  "version": "1.32.23",
   "description": "Self-hosted personal-health-tracking PWA with Withings integration, AI insights, and doctor-report PDF export.",
   "license": "PolyForm-Noncommercial-1.0.0",
   "homepage": "https://healthlog.dev",
diff --git a/public/sw.js b/public/sw.js
index f5da796c6..e9d38b708 100644
--- a/public/sw.js
+++ b/public/sw.js
@@ -36,7 +36,7 @@ try {
 // v1.4.38.4 → v1.4.42. Do not hand-edit; bump `package.json` and rebuild.
 const CACHE_VERSION =
   (typeof self !== "undefined" && self.__APP_VERSION__) ||
-  /* @sw-version-fallback */ "v1.32.22";
+  /* @sw-version-fallback */ "v1.32.23";
 const STATIC_CACHE = `healthlog-static-${CACHE_VERSION}`;
 const PAGE_CACHE = `healthlog-pages-${CACHE_VERSION}`;
 // v1.18.6 — read-only data cache for a curated allowlist of safe GET `/api/*`
diff --git a/src/app/api/strava/callback/__tests__/route.test.ts b/src/app/api/strava/callback/__tests__/route.test.ts
new file mode 100644
index 000000000..ec238315d
--- /dev/null
+++ b/src/app/api/strava/callback/__tests__/route.test.ts
@@ -0,0 +1,109 @@
+/**
+ * S-1 — the Strava OAuth callback enqueues the self-converging history backfill
+ * at connect time (mirroring the WHOOP / Fitbit callbacks) so deep history
+ * lands within the hour instead of waiting for the next worker reboot. A missing
+ * boss instance is a warning, never a failure — boot discovery is the net.
+ */
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { NextRequest } from "next/server";
+
+const {
+  bossSend,
+  getGlobalBossMock,
+  exchangeCodeMock,
+  getCredsMock,
+  userFindUnique,
+  userUpdate,
+  markReconnectedMock,
+} = vi.hoisted(() => ({
+  bossSend: vi.fn(async () => "job-id"),
+  getGlobalBossMock: vi.fn(),
+  exchangeCodeMock: vi.fn(),
+  getCredsMock: vi.fn(),
+  userFindUnique: vi.fn(),
+  userUpdate: vi.fn(async () => ({})),
+  markReconnectedMock: vi.fn(async () => {}),
+}));
+
+vi.mock("@/lib/api-handler", () => ({
+  apiHandler: <T extends (...args: unknown[]) => unknown>(fn: T) => fn,
+}));
+vi.mock("@/lib/db", () => ({
+  prisma: { user: { findUnique: userFindUnique, update: userUpdate } },
+}));
+vi.mock("@/lib/auth/session", () => ({ getSession: vi.fn(async () => null) }));
+vi.mock("@/lib/logging/context", () => ({
+  annotate: vi.fn(),
+  getEvent: () => ({
+    setAuth: vi.fn(),
+    setError: vi.fn(),
+    addWarning: vi.fn(),
+  }),
+}));
+vi.mock("@/lib/auth/audit", () => ({ auditLog: vi.fn(async () => {}) }));
+vi.mock("@/lib/crypto", () => ({ encrypt: (s: string) => `enc(${s})` }));
+vi.mock("@/lib/strava/client", () => ({ exchangeCode: exchangeCodeMock }));
+vi.mock("@/lib/strava/credentials", () => ({
+  getStravaClientCredentials: getCredsMock,
+}));
+vi.mock("@/lib/oauth/signed-state", () => ({
+  oauthStateCookieName: () => "strava_oauth_state",
+  stateMatchesCookie: () => true,
+  verifySignedState: () => ({ userId: "u1" }),
+}));
+vi.mock("@/lib/integrations/status", () => ({
+  markReconnected: markReconnectedMock,
+}));
+vi.mock("@/lib/jobs/strava-backfill", () => ({
+  STRAVA_BACKFILL_QUEUE: "strava-backfill",
+}));
+vi.mock("@/lib/jobs/boss-instance", () => ({
+  getGlobalBoss: getGlobalBossMock,
+}));
+
+import { GET } from "../route";
+
+process.env.NEXT_PUBLIC_APP_URL = "https://app.example";
+
+function callback(): Promise<{ headers: { get(k: string): string | null } }> {
+  const req = new NextRequest(
+    "http://localhost/api/strava/callback?code=abc&state=signed-state",
+    { headers: { cookie: "strava_oauth_state=signed-state" } },
+  );
+  return (GET as unknown as (r: NextRequest) => Promise<never>)(req);
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  getCredsMock.mockResolvedValue({ clientId: "c", clientSecret: "s" });
+  exchangeCodeMock.mockResolvedValue({
+    access_token: "at",
+    refresh_token: "rt",
+    athlete: { id: 42 },
+  });
+  userFindUnique.mockResolvedValue({ stravaAthleteId: null });
+  getGlobalBossMock.mockReturnValue({ send: bossSend });
+});
+
+describe("GET /api/strava/callback — S-1 backfill enqueue", () => {
+  it("enqueues one STRAVA_BACKFILL_QUEUE job for the connecting user", async () => {
+    const res = await callback();
+
+    expect(res.headers.get("location")).toContain("strava=connected");
+    expect(markReconnectedMock).toHaveBeenCalledWith("u1", "strava");
+    expect(bossSend).toHaveBeenCalledTimes(1);
+    expect(bossSend).toHaveBeenCalledWith(
+      "strava-backfill",
+      expect.objectContaining({ userId: "u1" }),
+    );
+  });
+
+  it("still connects when the boss instance is unavailable (warning, not failure)", async () => {
+    getGlobalBossMock.mockReturnValue(null);
+
+    const res = await callback();
+
+    expect(res.headers.get("location")).toContain("strava=connected");
+    expect(bossSend).not.toHaveBeenCalled();
+  });
+});
diff --git a/src/app/api/strava/callback/route.ts b/src/app/api/strava/callback/route.ts
index dd093e0d6..40934189e 100644
--- a/src/app/api/strava/callback/route.ts
+++ b/src/app/api/strava/callback/route.ts
@@ -12,6 +12,8 @@ import {
   verifySignedState,
 } from "@/lib/oauth/signed-state";
 import { markReconnected } from "@/lib/integrations/status";
+import { STRAVA_BACKFILL_QUEUE } from "@/lib/jobs/strava-backfill";
+import { getGlobalBoss } from "@/lib/jobs/boss-instance";
 import { NextRequest, NextResponse } from "next/server";
 
 /**
@@ -107,6 +109,24 @@ export const GET = apiHandler(async (request: NextRequest) => {
     await auditLog("strava.connect", { userId });
     await markReconnected(userId, "strava");
 
+    // Enqueue the self-converging history backfill at connect time so deep
+    // history lands within the hour instead of waiting for the next worker
+    // reboot. Best-effort: the boot-time discovery query
+    // (`stravaBackfillCompletedAt IS NULL`) is the safety net, so a missing
+    // boss instance here never strands the connection. Mirrors the WHOOP /
+    // Fitbit callback enqueue.
+    const boss = getGlobalBoss();
+    if (boss) {
+      await boss
+        .send(STRAVA_BACKFILL_QUEUE, {
+          userId,
+          enqueuedAt: new Date().toISOString(),
+        })
+        .catch((err) =>
+          getEvent()?.addWarning(`strava-backfill enqueue failed: ${err}`),
+        );
+    }
+
     const response = NextResponse.redirect(
       new URL(
         "/settings/integrations?strava=connected",
diff --git a/src/app/api/whoop/sync/__tests__/route.test.ts b/src/app/api/whoop/sync/__tests__/route.test.ts
index 953ae2c02..6e5f461e7 100644
--- a/src/app/api/whoop/sync/__tests__/route.test.ts
+++ b/src/app/api/whoop/sync/__tests__/route.test.ts
@@ -30,7 +30,7 @@ describe("POST /api/whoop/sync", () => {
   beforeEach(() => vi.clearAllMocks());
 
   it("triggers an incremental sync by default", async () => {
-    sync.mockResolvedValue(7);
+    sync.mockResolvedValue({ imported: 7, failed: false });
     const res = (await (
       POST as unknown as (r: NextRequest) => Promise<{ data: unknown }>
     )(req({}))) as { data: { imported: number; fullSync: boolean } };
@@ -40,7 +40,7 @@ describe("POST /api/whoop/sync", () => {
   });
 
   it("honours fullSync: true", async () => {
-    sync.mockResolvedValue(99);
+    sync.mockResolvedValue({ imported: 99, failed: false });
     const res = (await (
       POST as unknown as (r: NextRequest) => Promise<{ data: unknown }>
     )(req({ fullSync: true }))) as { data: { fullSync: boolean } };
diff --git a/src/app/api/whoop/sync/route.ts b/src/app/api/whoop/sync/route.ts
index 17d069ad4..d3a331aca 100644
--- a/src/app/api/whoop/sync/route.ts
+++ b/src/app/api/whoop/sync/route.ts
@@ -27,6 +27,6 @@ export const POST = apiHandler(async (request: NextRequest) => {
     // no body provided -> default incremental sync
   }
 
-  const imported = await syncUserWhoop(user.id, { fullSync });
+  const { imported } = await syncUserWhoop(user.id, { fullSync });
   return apiSuccess({ imported, fullSync });
 });
diff --git a/src/lib/integrations/__tests__/status.test.ts b/src/lib/integrations/__tests__/status.test.ts
index 7098e511c..6d78f1f55 100644
--- a/src/lib/integrations/__tests__/status.test.ts
+++ b/src/lib/integrations/__tests__/status.test.ts
@@ -47,6 +47,8 @@ import {
   isReauthRequired,
   getPersistentFailureThreshold,
   resumeIntegrationFromPark,
+  markSyncFailureRecorded,
+  isSyncFailureRecorded,
 } from "../status";
 import { prisma } from "@/lib/db";
 import { auditLog } from "@/lib/auth/audit";
@@ -856,3 +858,36 @@ describe("resumeIntegrationFromPark", () => {
     expect(auditLog).not.toHaveBeenCalled();
   });
 });
+
+describe("sync-failure-recorded marker (§5)", () => {
+  it("round-trips: a marked error reads back as recorded", () => {
+    const err = new Error("boom");
+    expect(isSyncFailureRecorded(err)).toBe(false);
+    const returned = markSyncFailureRecorded(err);
+    // Returns the SAME object so `throw markSyncFailureRecorded(err)` works.
+    expect(returned).toBe(err);
+    expect(isSyncFailureRecorded(err)).toBe(true);
+  });
+
+  it("the marker is non-enumerable (never serialised into logs / JSON)", () => {
+    const err = markSyncFailureRecorded(new Error("boom"));
+    expect(Object.keys(err)).not.toContain("healthlog.syncFailureRecorded");
+    expect(JSON.stringify({ ...err })).not.toContain("syncFailureRecorded");
+  });
+
+  it("is a no-op on non-objects and never reports them as recorded", () => {
+    expect(markSyncFailureRecorded("boom")).toBe("boom");
+    expect(markSyncFailureRecorded(null)).toBe(null);
+    expect(markSyncFailureRecorded(undefined)).toBe(undefined);
+    expect(isSyncFailureRecorded("boom")).toBe(false);
+    expect(isSyncFailureRecorded(null)).toBe(false);
+    expect(isSyncFailureRecorded(undefined)).toBe(false);
+  });
+
+  it("tolerates a frozen error without throwing (falls back to unmarked)", () => {
+    const frozen = Object.freeze(new Error("frozen"));
+    expect(() => markSyncFailureRecorded(frozen)).not.toThrow();
+    // Frozen can't carry the marker, so the boundary records it once — safe.
+    expect(isSyncFailureRecorded(frozen)).toBe(false);
+  });
+});
diff --git a/src/lib/integrations/status.ts b/src/lib/integrations/status.ts
index 953e0f4b9..8e87682b6 100644
--- a/src/lib/integrations/status.ts
+++ b/src/lib/integrations/status.ts
@@ -98,6 +98,51 @@ export function toFailureKind(
   return "transient";
 }
 
+/**
+ * Non-enumerable marker stamped on an error a provider sync ALREADY recorded on
+ * the integration ledger before rethrowing. The poll-cohort boundary
+ * (`makePollCohortHandler`) reads it so a record-then-rethrow failure is not
+ * recorded a SECOND time when it surfaces in the cohort catch — a double-record
+ * would inflate the per-kind failure buckets (firing the 3-strike admin alert a
+ * tick early) and churn `lastError`. A provider-blind recorder at the boundary
+ * would also persist an UNREDACTED message (e.g. Nightscout's token-bearing
+ * URL), so the marker keeps classification + redaction provider-owned: only an
+ * UNMARKED escape reaches the boundary recorder.
+ *
+ * No-op on non-objects; tolerant of a frozen error (the boundary then records
+ * it once, which is the correct fallback — never a double-record).
+ */
+const SYNC_FAILURE_RECORDED: unique symbol = Symbol(
+  "healthlog.syncFailureRecorded",
+);
+
+/** Stamp `err` as already-recorded and return it (for `throw markSync…(err)`). */
+export function markSyncFailureRecorded<T>(err: T): T {
+  if (err !== null && typeof err === "object") {
+    try {
+      Object.defineProperty(err, SYNC_FAILURE_RECORDED, {
+        value: true,
+        enumerable: false,
+        configurable: true,
+        writable: true,
+      });
+    } catch {
+      // A frozen / sealed error can't carry the marker; the boundary records
+      // it once — the safe fallback, never a double-record.
+    }
+  }
+  return err;
+}
+
+/** True when `err` was already recorded on the ledger by its source site. */
+export function isSyncFailureRecorded(err: unknown): boolean {
+  return (
+    err !== null &&
+    typeof err === "object" &&
+    (err as Record<symbol, unknown>)[SYNC_FAILURE_RECORDED] === true
+  );
+}
+
 /**
  * Recognised IntegrationStatus states.
  *
diff --git a/src/lib/jobs/__tests__/sleep-timeline-backfill.test.ts b/src/lib/jobs/__tests__/sleep-timeline-backfill.test.ts
index 710f923b9..7b816dc90 100644
--- a/src/lib/jobs/__tests__/sleep-timeline-backfill.test.ts
+++ b/src/lib/jobs/__tests__/sleep-timeline-backfill.test.ts
@@ -107,7 +107,7 @@ describe("enqueueBootTimeSleepTimelineBackfill — discovery", () => {
 describe("runSleepTimelineBackfillForUser", () => {
   it("WHOOP: deletes the source's sleep rows, full-syncs, and stamps the marker", async () => {
     prismaMock.measurement.deleteMany.mockResolvedValue({ count: 5 });
-    syncUserWhoop.mockResolvedValue(42);
+    syncUserWhoop.mockResolvedValue({ imported: 42, failed: false });
     prismaMock.whoopConnection.update.mockResolvedValue({});
 
     const { deleted, imported } = await runSleepTimelineBackfillForUser(
@@ -126,6 +126,18 @@ describe("runSleepTimelineBackfillForUser", () => {
     expect(updateArg.data.sleepTimelineBackfillAt).toBeInstanceOf(Date);
   });
 
+  it("WHOOP: a failed verdict THROWS without stamping the marker (gated re-sync)", async () => {
+    // The rows were already deleted; a partial re-sync must not stamp the
+    // completion marker over the gap — it throws so pg-boss retries.
+    prismaMock.measurement.deleteMany.mockResolvedValue({ count: 5 });
+    syncUserWhoop.mockResolvedValue({ imported: 3, failed: true });
+
+    await expect(
+      runSleepTimelineBackfillForUser("w1", "WHOOP"),
+    ).rejects.toThrow(/incomplete/);
+    expect(prismaMock.whoopConnection.update).not.toHaveBeenCalled();
+  });
+
   it("WITHINGS: deletes the source's sleep rows, re-syncs, and stamps the marker", async () => {
     prismaMock.measurement.deleteMany.mockResolvedValue({ count: 3 });
     syncWithingsSleep.mockResolvedValue(7);
diff --git a/src/lib/jobs/__tests__/whoop-backfill.test.ts b/src/lib/jobs/__tests__/whoop-backfill.test.ts
index e6573ad2d..7cb6404e4 100644
--- a/src/lib/jobs/__tests__/whoop-backfill.test.ts
+++ b/src/lib/jobs/__tests__/whoop-backfill.test.ts
@@ -7,16 +7,18 @@
  */
 import { beforeEach, describe, expect, it, vi } from "vitest";
 
-const { prismaMock, bossSend, syncUserWhoop } = vi.hoisted(() => ({
-  prismaMock: {
-    whoopConnection: {
-      findMany: vi.fn(),
-      update: vi.fn(),
+const { prismaMock, bossSend, syncUserWhoop, isReauthRequiredMock } =
+  vi.hoisted(() => ({
+    prismaMock: {
+      whoopConnection: {
+        findMany: vi.fn(),
+        update: vi.fn(),
+      },
     },
-  },
-  bossSend: vi.fn(),
-  syncUserWhoop: vi.fn(),
-}));
+    bossSend: vi.fn(),
+    syncUserWhoop: vi.fn(),
+    isReauthRequiredMock: vi.fn(async () => false),
+  }));
 
 vi.mock("@/lib/db", () => ({ prisma: prismaMock }));
 
@@ -28,6 +30,10 @@ vi.mock("@/lib/whoop/sync", () => ({
   syncUserWhoop: (...a: unknown[]) => syncUserWhoop(...a),
 }));
 
+vi.mock("@/lib/integrations/status", () => ({
+  isReauthRequired: isReauthRequiredMock,
+}));
+
 vi.mock("@/lib/logging/context", () => ({
   annotate: () => {},
   getEvent: () => null,
@@ -40,6 +46,8 @@ import {
 
 beforeEach(() => {
   vi.clearAllMocks();
+  isReauthRequiredMock.mockResolvedValue(false);
+  prismaMock.whoopConnection.update.mockResolvedValue({});
 });
 
 describe("enqueueBootTimeWhoopBackfill — discovery", () => {
@@ -85,10 +93,9 @@ describe("enqueueBootTimeWhoopBackfill — discovery", () => {
   });
 });
 
-describe("runWhoopBackfillForUser", () => {
-  it("runs a full sync and stamps backfillCompletedAt", async () => {
-    syncUserWhoop.mockResolvedValue(123);
-    prismaMock.whoopConnection.update.mockResolvedValue({});
+describe("runWhoopBackfillForUser — verdict-gated marker", () => {
+  it("stamps backfillCompletedAt after a CLEAN full-history run", async () => {
+    syncUserWhoop.mockResolvedValue({ imported: 123, failed: false });
 
     const { imported } = await runWhoopBackfillForUser("u1");
 
@@ -98,4 +105,21 @@ describe("runWhoopBackfillForUser", () => {
     expect(updateArg.where).toEqual({ userId: "u1" });
     expect(updateArg.data.backfillCompletedAt).toBeInstanceOf(Date);
   });
+
+  it("a failed verdict THROWS without stamping — pg-boss retries become real", async () => {
+    syncUserWhoop.mockResolvedValue({ imported: 7, failed: true });
+
+    await expect(runWhoopBackfillForUser("u1")).rejects.toThrow(/incomplete/);
+    expect(prismaMock.whoopConnection.update).not.toHaveBeenCalled();
+  });
+
+  it("a connection parked at error_reauth returns WITHOUT running the sync or stamping", async () => {
+    isReauthRequiredMock.mockResolvedValue(true);
+
+    await expect(runWhoopBackfillForUser("u1")).resolves.toEqual({
+      imported: 0,
+    });
+    expect(syncUserWhoop).not.toHaveBeenCalled();
+    expect(prismaMock.whoopConnection.update).not.toHaveBeenCalled();
+  });
 });
diff --git a/src/lib/jobs/__tests__/whoop-resource-sync.test.ts b/src/lib/jobs/__tests__/whoop-resource-sync.test.ts
index a7469d718..295ae98e6 100644
--- a/src/lib/jobs/__tests__/whoop-resource-sync.test.ts
+++ b/src/lib/jobs/__tests__/whoop-resource-sync.test.ts
@@ -10,17 +10,38 @@
 import { beforeEach, describe, expect, it, vi } from "vitest";
 import type { Job } from "pg-boss";
 
-const { syncUserWorkout, syncWhoopWorkoutById, findManyMock } = vi.hoisted(
-  () => ({
-    syncUserWorkout: vi.fn<(...a: unknown[]) => Promise<number>>(async () => 0),
-    syncWhoopWorkoutById: vi.fn<(...a: unknown[]) => Promise<number>>(
-      async () => 0,
-    ),
-    findManyMock: vi.fn<
-      (...a: unknown[]) => Promise<Array<{ userId: string }>>
-    >(async () => []),
-  }),
-);
+const {
+  syncUserWorkout,
+  syncWhoopWorkoutById,
+  findManyMock,
+  recordWhoopSyncFailureMock,
+  recordSyncSuccessMock,
+} = vi.hoisted(() => ({
+  syncUserWorkout: vi.fn<(...a: unknown[]) => Promise<number>>(async () => 0),
+  syncWhoopWorkoutById: vi.fn<(...a: unknown[]) => Promise<number>>(
+    async () => 0,
+  ),
+  findManyMock: vi.fn<(...a: unknown[]) => Promise<Array<{ userId: string }>>>(
+    async () => [],
+  ),
+  recordWhoopSyncFailureMock: vi.fn<(...a: unknown[]) => Promise<void>>(
+    async () => {},
+  ),
+  recordSyncSuccessMock: vi.fn<(...a: unknown[]) => Promise<void>>(
+    async () => {},
+  ),
+}));
+
+// Keep the real marker helpers (isSyncFailureRecorded / markSyncFailureRecorded)
+// but stub the DB-touching writers so this stays a unit test.
+vi.mock("@/lib/integrations/status", async (orig) => ({
+  ...(await orig<typeof import("@/lib/integrations/status")>()),
+  recordSyncSuccess: recordSyncSuccessMock,
+}));
+vi.mock("@/lib/whoop/sync-core", async (orig) => ({
+  ...(await orig<typeof import("@/lib/whoop/sync-core")>()),
+  recordWhoopSyncFailure: recordWhoopSyncFailureMock,
+}));
 
 vi.mock("@/lib/whoop/sync-recovery", () => ({
   syncUserRecovery: vi.fn(async () => 0),
@@ -63,6 +84,7 @@ vi.mock("../reminder/shared", () => ({
 }));
 
 import { handleWhoopWorkoutSync } from "../reminder/whoop-sync";
+import { markSyncFailureRecorded } from "@/lib/integrations/status";
 
 function job(data: { userId?: string; resourceId?: string }): Job<{
   userId?: string;
@@ -111,3 +133,32 @@ describe("runWhoopResourceSync dispatch", () => {
     expect(syncUserWorkout).toHaveBeenCalledTimes(2);
   });
 });
+
+describe("runWhoopResourceSync — WH-4 write-path ledger honesty", () => {
+  it("records an UNMARKED write-path throw once (a stale-green pill otherwise)", async () => {
+    // A `MeasurementReconciliationError` out of the upsert reaches no ledger on
+    // the cron path before WH-4 — the pill stays green through a persistent
+    // write failure. The catch now records it once.
+    syncUserWorkout.mockRejectedValueOnce(new Error("write failed"));
+
+    await handleWhoopWorkoutSync([job({ userId: "u1" })]);
+
+    expect(recordWhoopSyncFailureMock).toHaveBeenCalledTimes(1);
+    expect(recordWhoopSyncFailureMock).toHaveBeenCalledWith(
+      "u1",
+      expect.objectContaining({ message: "write failed" }),
+    );
+  });
+
+  it("does NOT re-record a MARKED fetch error (no double-record)", async () => {
+    // A fetch hard-fail was already recorded + marked in
+    // `handleCollectionFetchError`; the cron catch must skip it.
+    syncUserWorkout.mockRejectedValueOnce(
+      markSyncFailureRecorded(new Error("already recorded fetch error")),
+    );
+
+    await handleWhoopWorkoutSync([job({ userId: "u1" })]);
+
+    expect(recordWhoopSyncFailureMock).not.toHaveBeenCalled();
+  });
+});
diff --git a/src/lib/jobs/__tests__/withings-ecg-worker.test.ts b/src/lib/jobs/__tests__/withings-ecg-worker.test.ts
index 05de54a0a..cb11bde9e 100644
--- a/src/lib/jobs/__tests__/withings-ecg-worker.test.ts
+++ b/src/lib/jobs/__tests__/withings-ecg-worker.test.ts
@@ -52,9 +52,15 @@ vi.mock("@/lib/logging/background", () => ({
 vi.mock("@/lib/logging/fire-and-forget", () => ({
   fireAndForget: vi.fn(),
 }));
+const { ecgFindMany } = vi.hoisted(() => ({
+  ecgFindMany: vi.fn<(...a: unknown[]) => Promise<Array<{ userId: string }>>>(
+    async () => [],
+  ),
+}));
+
 vi.mock("../reminder/shared", () => ({
   getWorkerPrisma: vi.fn(() => ({
-    withingsConnection: { findMany: vi.fn(async () => []) },
+    withingsConnection: { findMany: (...a: unknown[]) => ecgFindMany(...a) },
   })),
 }));
 
@@ -69,6 +75,7 @@ function job(data: WithingsEcgSyncPayload): Job<WithingsEcgSyncPayload> {
 
 beforeEach(() => {
   vi.clearAllMocks();
+  ecgFindMany.mockResolvedValue([]);
 });
 const registrarSource = readFileSync(
   join(process.cwd(), "src/lib/jobs/reminder/register-integration-sync.ts"),
@@ -76,10 +83,8 @@ const registrarSource = readFileSync(
 );
 
 describe("handleWithingsEcgSync", () => {
-  it("rejects a failed source write so pg-boss can retry the same job", async () => {
-    syncUserEcg
-      .mockRejectedValueOnce(new Error("source write failed"))
-      .mockResolvedValueOnce(1);
+  it("a webhook job (userId + window) does a targeted date-windowed sync", async () => {
+    syncUserEcg.mockResolvedValue(1);
     const queued = job({
       userId: "user-1",
       eventId: "wu-1:1:1715000000:1715000060",
@@ -88,20 +93,42 @@ describe("handleWithingsEcgSync", () => {
       enddate: 1715000060,
     });
 
-    await expect(handleWithingsEcgSync([queued])).rejects.toThrow(
-      "source write failed",
-    );
     await expect(handleWithingsEcgSync([queued])).resolves.toBeUndefined();
 
+    expect(ecgFindMany).not.toHaveBeenCalled();
+    expect(syncUserEcg).toHaveBeenCalledTimes(1);
+    expect(syncUserEcg).toHaveBeenCalledWith("user-1", {
+      startdate: 1715000000,
+      enddate: 1715000060,
+    });
+  });
+
+  it("a payload-less cron tick walks the connection cohort with the default window", async () => {
+    // W-1 — the catch-net that lets a watch-only account (no scale, appli 54
+    // unsubscribed) pull its ECG strips: no userId → iterate every connection
+    // with `syncUserEcg(userId)` (default trailing-30-day window).
+    ecgFindMany.mockResolvedValue([{ userId: "a" }, { userId: "b" }]);
+    syncUserEcg.mockResolvedValue(0);
+
+    await handleWithingsEcgSync([job({} as WithingsEcgSyncPayload)]);
+
+    expect(ecgFindMany).toHaveBeenCalledTimes(1);
+    expect(syncUserEcg).toHaveBeenCalledTimes(2);
+    expect(syncUserEcg).toHaveBeenNthCalledWith(1, "a", {});
+    expect(syncUserEcg).toHaveBeenNthCalledWith(2, "b", {});
+  });
+
+  it("one user's failure never starves the rest of the cohort", async () => {
+    ecgFindMany.mockResolvedValue([{ userId: "a" }, { userId: "b" }]);
+    syncUserEcg.mockRejectedValueOnce(new Error("boom for a"));
+
+    // Per-user catch-and-warn (mirrors the activity / sleep handlers): the
+    // handler resolves, both users attempted, the leaf records its own ledger
+    // failure so honesty is preserved without rejecting the whole batch.
+    await expect(
+      handleWithingsEcgSync([job({} as WithingsEcgSyncPayload)]),
+    ).resolves.toBeUndefined();
     expect(syncUserEcg).toHaveBeenCalledTimes(2);
-    expect(syncUserEcg).toHaveBeenNthCalledWith(1, "user-1", {
-      startdate: 1715000000,
-      enddate: 1715000060,
-    });
-    expect(syncUserEcg).toHaveBeenNthCalledWith(2, "user-1", {
-      startdate: 1715000000,
-      enddate: 1715000060,
-    });
   });
 });
 
diff --git a/src/lib/jobs/__tests__/withings-queues.test.ts b/src/lib/jobs/__tests__/withings-queues.test.ts
index c525e1a04..5dc7dac08 100644
--- a/src/lib/jobs/__tests__/withings-queues.test.ts
+++ b/src/lib/jobs/__tests__/withings-queues.test.ts
@@ -76,4 +76,15 @@ describe("reminder-worker — Withings activity + sleep v2 queues", () => {
     );
     expect(source).toMatch(/\[WITHINGS_SLEEP_QUEUE,\s*WITHINGS_SLEEP_CRON\]/);
   });
+
+  it("schedules the ECG catch-net cron at :41 so watch-only accounts pull strips", () => {
+    // The queue is already in allQueues + boss.work-bound; W-1 adds the missing
+    // schedule entry so a payload-less cron tick walks the connection cohort.
+    expect(source).toMatch(
+      /WITHINGS_ECG_SYNC_CRON\s*=\s*["']41 \* \* \* \*["']/,
+    );
+    expect(source).toMatch(
+      /\[WITHINGS_ECG_SYNC_QUEUE,\s*WITHINGS_ECG_SYNC_CRON\]/,
+    );
+  });
 });
diff --git a/src/lib/jobs/reminder/__tests__/polar-sync-legs.test.ts b/src/lib/jobs/reminder/__tests__/polar-sync-legs.test.ts
index 65ab44cd4..3d1c30923 100644
--- a/src/lib/jobs/reminder/__tests__/polar-sync-legs.test.ts
+++ b/src/lib/jobs/reminder/__tests__/polar-sync-legs.test.ts
@@ -5,7 +5,12 @@ const { syncUserPolar, syncUserPolarWorkouts } = vi.hoisted(() => ({
   syncUserPolarWorkouts: vi.fn(),
 }));
 
-vi.mock("@/lib/polar/sync", () => ({ syncUserPolar }));
+vi.mock("@/lib/polar/sync", () => ({
+  syncUserPolar,
+  // The cohort config wires `recordPolarSyncFailure` as its recorder; the legs
+  // handler imports the module, so the mock must expose it too.
+  recordPolarSyncFailure: vi.fn(async () => {}),
+}));
 vi.mock("@/lib/polar/sync-workouts", () => ({ syncUserPolarWorkouts }));
 
 import { syncUserPolarLegs } from "../polar-sync";
diff --git a/src/lib/jobs/reminder/__tests__/poll-cohort.test.ts b/src/lib/jobs/reminder/__tests__/poll-cohort.test.ts
new file mode 100644
index 000000000..f0dc9123d
--- /dev/null
+++ b/src/lib/jobs/reminder/__tests__/poll-cohort.test.ts
@@ -0,0 +1,115 @@
+/**
+ * §5 — the poll-cohort factory boundary. A provider that records-then-rethrows
+ * marks its error so the boundary does NOT record it a second time (which would
+ * inflate the per-kind buckets and, for Nightscout, risk re-persisting a
+ * token-bearing URL). An UNMARKED escape — today's Oura / Polar write-path throw
+ * — is recorded exactly once through the per-provider `recordFailure` callback.
+ * A recorder rejection never breaks the cohort loop.
+ */
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import type { Job } from "pg-boss";
+
+const warnings: string[] = [];
+
+vi.mock("@/lib/jobs/worker-status", () => ({ recordError: vi.fn() }));
+vi.mock("@/lib/jobs/reminder-satisfy", () => ({
+  enqueueReminderSatisfy: vi.fn(async () => undefined),
+}));
+vi.mock("@/lib/logging/fire-and-forget", () => ({ fireAndForget: vi.fn() }));
+vi.mock("@/lib/logging/background", () => ({
+  withBackgroundEvent: async (
+    _name: string,
+    fn: (evt: {
+      setBackground: () => void;
+      setError: () => void;
+      addWarning: (w: string) => void;
+    }) => Promise<void>,
+  ) =>
+    fn({
+      setBackground: vi.fn(),
+      setError: vi.fn(),
+      addWarning: (w: string) => warnings.push(w),
+    }),
+}));
+vi.mock("../shared", () => ({
+  getWorkerPrisma: () => ({}),
+}));
+
+import { makePollCohortHandler } from "../poll-cohort";
+import { markSyncFailureRecorded } from "@/lib/integrations/status";
+
+function job(userId?: string): Job<{ userId?: string }> {
+  return { data: userId ? { userId } : {} } as Job<{ userId?: string }>;
+}
+
+beforeEach(() => {
+  warnings.length = 0;
+  vi.clearAllMocks();
+});
+
+describe("makePollCohortHandler — marker-aware recordFailure boundary", () => {
+  it("records an UNMARKED escape once, then warns, and continues the cohort", async () => {
+    const recordFailure = vi.fn(async () => {});
+    const syncUser = vi.fn(async (userId: string) => {
+      if (userId === "boom") throw new Error("unmarked write failure");
+      return 1;
+    });
+    const handler = makePollCohortHandler({
+      taskName: "job.test_sync",
+      findCohort: async () => ["a", "boom", "b"],
+      syncUser,
+      recordFailure,
+    });
+
+    await handler([job()]);
+
+    // The failing user is recorded once and warned; the other two still sync.
+    expect(syncUser).toHaveBeenCalledTimes(3);
+    expect(recordFailure).toHaveBeenCalledTimes(1);
+    expect(recordFailure).toHaveBeenCalledWith(
+      "boom",
+      expect.objectContaining({ message: "unmarked write failure" }),
+    );
+    expect(warnings.some((w) => w.includes("boom"))).toBe(true);
+  });
+
+  it("does NOT record a MARKED error (the source already recorded it)", async () => {
+    const recordFailure = vi.fn(async () => {});
+    const syncUser = vi.fn(async () => {
+      throw markSyncFailureRecorded(new Error("already recorded at source"));
+    });
+    const handler = makePollCohortHandler({
+      taskName: "job.test_sync",
+      findCohort: async () => ["a"],
+      syncUser,
+      recordFailure,
+    });
+
+    await handler([job()]);
+
+    expect(recordFailure).not.toHaveBeenCalled();
+    // Still warned so the cohort event carries the failure.
+    expect(warnings.some((w) => w.includes("already recorded"))).toBe(true);
+  });
+
+  it("a recorder rejection never breaks the cohort loop", async () => {
+    const recordFailure = vi.fn(async () => {
+      throw new Error("recorder down");
+    });
+    const syncUser = vi.fn(async (userId: string) => {
+      if (userId === "boom") throw new Error("unmarked");
+      return 1;
+    });
+    const handler = makePollCohortHandler({
+      taskName: "job.test_sync",
+      findCohort: async () => ["boom", "next"],
+      syncUser,
+      recordFailure,
+    });
+
+    await expect(handler([job()])).resolves.toBeUndefined();
+    // The next user still synced despite the recorder throwing.
+    expect(syncUser).toHaveBeenCalledTimes(2);
+    expect(syncUser).toHaveBeenLastCalledWith("next");
+  });
+});
diff --git a/src/lib/jobs/reminder/nightscout-sync.ts b/src/lib/jobs/reminder/nightscout-sync.ts
index 1a97f24b1..76cbc7b57 100644
--- a/src/lib/jobs/reminder/nightscout-sync.ts
+++ b/src/lib/jobs/reminder/nightscout-sync.ts
@@ -9,7 +9,10 @@
  * `./poll-cohort`; reminder-worker.ts owns the queue name, cron schedule, and
  * boss.work registration.
  */
-import { syncUserNightscout } from "@/lib/nightscout/sync";
+import {
+  recordNightscoutSyncFailure,
+  syncUserNightscout,
+} from "@/lib/nightscout/sync";
 import { makePollCohortHandler, type PollCohortPayload } from "./poll-cohort";
 
 export type NightscoutSyncPayload = PollCohortPayload;
@@ -25,4 +28,8 @@ export const handleNightscoutSync = makePollCohortHandler({
     return users.map((u) => u.id);
   },
   syncUser: syncUserNightscout,
+  // The fetch path already records + marks its own failure (token-redacted), so
+  // this fires only for a future UNMARKED escape — and redacts the token before
+  // the message reaches the ledger.
+  recordFailure: recordNightscoutSyncFailure,
 });
diff --git a/src/lib/jobs/reminder/oura-sync.ts b/src/lib/jobs/reminder/oura-sync.ts
index 5ca264c4e..a22d2f9ad 100644
--- a/src/lib/jobs/reminder/oura-sync.ts
+++ b/src/lib/jobs/reminder/oura-sync.ts
@@ -7,7 +7,7 @@
  * lives in `./poll-cohort`; the queue name, cron schedule, and boss.work
  * registration live in reminder-worker.ts.
  */
-import { syncUserOura } from "@/lib/oura/sync";
+import { recordOuraSyncFailure, syncUserOura } from "@/lib/oura/sync";
 import { makePollCohortHandler, type PollCohortPayload } from "./poll-cohort";
 
 export type OuraSyncPayload = PollCohortPayload;
@@ -22,4 +22,7 @@ export const handleOuraSync = makePollCohortHandler({
     return users.map((u) => u.id);
   },
   syncUser: syncUserOura,
+  // Catches an UNMARKED escape — today the `upsertOuraMeasurements` write-path
+  // throw (the fetch/refresh path already records + marks its own failures).
+  recordFailure: recordOuraSyncFailure,
 });
diff --git a/src/lib/jobs/reminder/polar-sync.ts b/src/lib/jobs/reminder/polar-sync.ts
index b73efee48..ae06b02c9 100644
--- a/src/lib/jobs/reminder/polar-sync.ts
+++ b/src/lib/jobs/reminder/polar-sync.ts
@@ -13,7 +13,7 @@
  * reminder-worker.ts — no new queue: the workout leg rides the existing hourly
  * `polar-sync` tick (one extra request per connected user per hour).
  */
-import { syncUserPolar } from "@/lib/polar/sync";
+import { recordPolarSyncFailure, syncUserPolar } from "@/lib/polar/sync";
 import { syncUserPolarWorkouts } from "@/lib/polar/sync-workouts";
 import { makePollCohortHandler, type PollCohortPayload } from "./poll-cohort";
 
@@ -63,4 +63,8 @@ export const handlePolarSync = makePollCohortHandler({
     return users.map((u) => u.id);
   },
   syncUser: syncUserPolarLegs,
+  // Catches an UNMARKED escape — today the `upsertPolarMeasurements` /
+  // `upsertPolarWorkouts` write-path throws (the fetch paths record + mark
+  // their own failures, and the legs wrapper rethrows the marked error).
+  recordFailure: recordPolarSyncFailure,
 });
diff --git a/src/lib/jobs/reminder/poll-cohort.ts b/src/lib/jobs/reminder/poll-cohort.ts
index 2e716552b..a24a12ff3 100644
--- a/src/lib/jobs/reminder/poll-cohort.ts
+++ b/src/lib/jobs/reminder/poll-cohort.ts
@@ -23,6 +23,7 @@ import { fireAndForget } from "@/lib/logging/fire-and-forget";
 import { recordError } from "@/lib/jobs/worker-status";
 import { withBackgroundEvent } from "@/lib/logging/background";
 import { enqueueReminderSatisfy } from "@/lib/jobs/reminder-satisfy";
+import { isSyncFailureRecorded } from "@/lib/integrations/status";
 import { getWorkerPrisma } from "./shared";
 
 /** Every poll-cohort handler accepts an optional single-user payload. */
@@ -40,6 +41,16 @@ export interface PollCohortConfig {
   findCohort: (prisma: ReturnType<typeof getWorkerPrisma>) => Promise<string[]>;
   /** Sync one user; returns the count of measurements imported. */
   syncUser: (userId: string) => Promise<number>;
+  /**
+   * Record a per-user sync failure that escaped `syncUser` UNRECORDED. Called
+   * only for an error the source site did not already mark via
+   * `markSyncFailureRecorded` — so a provider that records-then-rethrows never
+   * double-records, and the recorder keeps classification + secret redaction
+   * provider-owned (a boundary-blind recorder would leak Nightscout's
+   * token-bearing URL into `lastError`). A rejection here never breaks the
+   * cohort loop.
+   */
+  recordFailure: (userId: string, err: unknown) => Promise<void>;
 }
 
 /**
@@ -52,6 +63,7 @@ export function makePollCohortHandler({
   taskName,
   findCohort,
   syncUser,
+  recordFailure,
 }: PollCohortConfig) {
   return async function handlePollCohort(jobs: Job<PollCohortPayload>[]) {
     await withBackgroundEvent(taskName, async (evt) => {
@@ -82,6 +94,18 @@ export function makePollCohortHandler({
               });
             }
           } catch (err) {
+            // A record-then-rethrow provider already stamped the ledger and
+            // marked the error; recording again would double-count the streak
+            // and (for Nightscout) risk re-persisting an unredacted message.
+            // Only an UNMARKED escape — today's Oura / Polar write-path throw,
+            // or any future provider path — is recorded here.
+            if (!isSyncFailureRecorded(err)) {
+              await recordFailure(userId, err).catch((recErr) => {
+                evt.addWarning(
+                  `${taskName} recordFailure failed for user ${userId}: ${recErr}`,
+                );
+              });
+            }
             evt.addWarning(`${taskName} failed for user ${userId}: ${err}`);
           }
         }
diff --git a/src/lib/jobs/reminder/register-integration-sync.ts b/src/lib/jobs/reminder/register-integration-sync.ts
index 6fe050510..eaaf55544 100644
--- a/src/lib/jobs/reminder/register-integration-sync.ts
+++ b/src/lib/jobs/reminder/register-integration-sync.ts
@@ -137,6 +137,14 @@ const WITHINGS_ACTIVITY_CRON = "0 * * * *"; // every hour at :00
 const WITHINGS_SLEEP_QUEUE = "withings-sleep-sync";
 
 const WITHINGS_SLEEP_CRON = "15 * * * *"; // every hour at :15
+// v1.32.23 — Withings ECG cron catch-net. The queue is webhook-primary
+// (appli=54 → `enqueueWithingsEcgSync`), but appli 54 is not in the
+// subscription set and the manual sync route measures only, so a ScanWatch-only
+// account (no scale) never had its ECG strips pulled. An hourly cohort walk
+// (one `v2/heart list` call per connected user, empty + cheap for non-ECG
+// devices) closes the gap. :41 is a free minute (used: 0,5,8,11,13,15,17,18,
+// 20,30,35,50) staggered off every other hourly sync tick.
+const WITHINGS_ECG_SYNC_CRON = "41 * * * *"; // every hour at :41
 
 const MOODLOG_SYNC_QUEUE = "moodlog-sync";
 
@@ -310,6 +318,9 @@ const schedules: ScheduleEntry[] = [
   [WITHINGS_SYNC_QUEUE, WITHINGS_SYNC_CRON],
   [WITHINGS_ACTIVITY_QUEUE, WITHINGS_ACTIVITY_CRON],
   [WITHINGS_SLEEP_QUEUE, WITHINGS_SLEEP_CRON],
+  // v1.32.23 — hourly ECG catch-net (:41) so watch-only accounts pull their
+  // strips without a webhook or a scale.
+  [WITHINGS_ECG_SYNC_QUEUE, WITHINGS_ECG_SYNC_CRON],
   [MOODLOG_SYNC_QUEUE, MOODLOG_SYNC_CRON],
   [WITHINGS_OAUTH_STATE_CLEANUP_QUEUE, WITHINGS_OAUTH_STATE_CLEANUP_CRON],
   // v1.11.0 — WHOOP poll-fallback crons. Recovery/sleep/workout catch
diff --git a/src/lib/jobs/reminder/strava-sync.ts b/src/lib/jobs/reminder/strava-sync.ts
index b3e6e1b0d..660d2a9d8 100644
--- a/src/lib/jobs/reminder/strava-sync.ts
+++ b/src/lib/jobs/reminder/strava-sync.ts
@@ -11,7 +11,7 @@
  * The queue name, cron schedule, and boss.work registration live in
  * `register-integration-sync.ts`.
  */
-import { syncUserStrava } from "@/lib/strava/sync";
+import { recordStravaFailure, syncUserStrava } from "@/lib/strava/sync";
 import { makePollCohortHandler, type PollCohortPayload } from "./poll-cohort";
 
 export type StravaSyncPayload = PollCohortPayload;
@@ -26,4 +26,8 @@ export const handleStravaSync = makePollCohortHandler({
     return users.map((u) => u.id);
   },
   syncUser: (userId) => syncUserStrava(userId),
+  // Strava records + marks every failure at its source today, so this is inert
+  // now — it's the net for a future unmarked escape (matching the cohort's
+  // contract that every provider supplies a recorder).
+  recordFailure: recordStravaFailure,
 });
diff --git a/src/lib/jobs/reminder/whoop-sync.ts b/src/lib/jobs/reminder/whoop-sync.ts
index a99c33358..b8df364f5 100644
--- a/src/lib/jobs/reminder/whoop-sync.ts
+++ b/src/lib/jobs/reminder/whoop-sync.ts
@@ -21,7 +21,11 @@ import {
   syncUserWorkout,
   syncWhoopWorkoutById,
 } from "@/lib/whoop/sync-workout";
-import { syncWhoopResourceWithStatus } from "@/lib/whoop/sync-core";
+import {
+  recordWhoopSyncFailure,
+  syncWhoopResourceWithStatus,
+} from "@/lib/whoop/sync-core";
+import { isSyncFailureRecorded } from "@/lib/integrations/status";
 import { enqueueReminderSatisfy } from "@/lib/jobs/reminder-satisfy";
 import { getWorkerPrisma } from "./shared";
 
@@ -110,6 +114,13 @@ export async function runWhoopResourceSync(
             });
           }
         } catch (err) {
+          // WH-4: a write-path throw on the hourly cron reaches no ledger
+          // otherwise (stale-green pill). Fetch hard-fails already recorded +
+          // marked in `handleCollectionFetchError`, so record only the UNMARKED
+          // escapes here.
+          if (!isSyncFailureRecorded(err)) {
+            await recordWhoopSyncFailure(userId, err);
+          }
           evt.addWarning(`${taskName} failed for user ${userId}: ${err}`);
         }
       }
diff --git a/src/lib/jobs/reminder/withings-sync.ts b/src/lib/jobs/reminder/withings-sync.ts
index fbfd828a8..96be0b354 100644
--- a/src/lib/jobs/reminder/withings-sync.ts
+++ b/src/lib/jobs/reminder/withings-sync.ts
@@ -108,25 +108,72 @@ export async function handleWithingsFallbackSync(
 }
 
 /**
- * Drain webhook-owned ECG events. A failed source read or write is allowed to
- * reject the handler so pg-boss retains the job and applies its retry policy.
+ * ECG sync handler. Two enqueue paths feed this queue, mirroring the
+ * activity / sleep handlers:
+ *
+ *   1. Webhook (appli=54) — payload carries `userId` (+ the source
+ *      `startdate`/`enddate` window); the handler runs `syncUserEcg` for that
+ *      one user over the windowed range.
+ *   2. Cron (`withings-ecg-sync` at :41) — payload has no `userId`, the handler
+ *      iterates every Withings connection and runs `syncUserEcg` over its
+ *      default trailing 30-day window. This is the catch-net that lets a
+ *      watch-only account (no scale, appli 54 unsubscribed) pull its ECG strips
+ *      without a webhook.
+ *
+ * Per-user failures are warned and the cohort carries on so one user's
+ * parked-at-reauth state (or a transient device outage) never starves the rest;
+ * the ECG leaf records its own classified failure on the shared `withings`
+ * ledger, so honesty is preserved without rejecting the whole batch.
  */
 export async function handleWithingsEcgSync(
   jobs: Job<WithingsEcgSyncPayload>[],
 ) {
   await withBackgroundEvent("job.withings_ecg_sync", async (evt) => {
+    const prisma = getWorkerPrisma();
     try {
-      let recordingsImported = 0;
+      const targets: Array<{
+        userId: string;
+        startdate?: number;
+        enddate?: number;
+      }> = [];
       for (const job of jobs) {
-        recordingsImported += await syncUserEcg(job.data.userId, {
-          startdate: job.data.startdate,
-          enddate: job.data.enddate,
-        });
+        if (job.data?.userId) {
+          targets.push({
+            userId: job.data.userId,
+            startdate: job.data.startdate,
+            enddate: job.data.enddate,
+          });
+        }
       }
+      // No user-specific enqueue → cron fallback iterating every connection.
+      if (targets.length === 0) {
+        const connections = await prisma.withingsConnection.findMany({
+          select: { userId: true },
+        });
+        targets.push(...connections);
+      }
+      if (targets.length === 0) return;
+
+      let usersSynced = 0;
+      let recordingsImported = 0;
+      for (const { userId, startdate, enddate } of targets) {
+        try {
+          const options =
+            startdate === undefined && enddate === undefined
+              ? {}
+              : { startdate, enddate };
+          recordingsImported += await syncUserEcg(userId, options);
+          usersSynced++;
+        } catch (err) {
+          evt.addWarning(`Withings ECG sync failed for user ${userId}: ${err}`);
+        }
+      }
+
       evt.setBackground({
         task_name: "job.withings_ecg_sync",
         result: {
-          events_processed: jobs.length,
+          users_synced: usersSynced,
+          total: targets.length,
           recordings_imported: recordingsImported,
         },
       });
diff --git a/src/lib/jobs/sleep-timeline-backfill.ts b/src/lib/jobs/sleep-timeline-backfill.ts
index 5cee00849..33aed68bf 100644
--- a/src/lib/jobs/sleep-timeline-backfill.ts
+++ b/src/lib/jobs/sleep-timeline-backfill.ts
@@ -71,7 +71,17 @@ export async function runSleepTimelineBackfillForUser(
 
   let imported = 0;
   if (provider === "WHOOP") {
-    imported = await syncUserWhoop(userId, { fullSync: true });
+    // `syncUserWhoop` now returns a verdict; gate the completion marker on a
+    // clean run so a partial re-sync (dead token, write failure) throws for a
+    // pg-boss retry instead of freezing the timeline gap under a stamped
+    // marker — the same discipline the WHOOP/Fitbit backfills use.
+    const result = await syncUserWhoop(userId, { fullSync: true });
+    imported = result.imported;
+    if (result.failed) {
+      throw new Error(
+        `sleep-timeline backfill incomplete for user ${userId} (whoop) — marker not stamped`,
+      );
+    }
     await prisma.whoopConnection.update({
       where: { userId },
       data: { sleepTimelineBackfillAt: new Date() },
diff --git a/src/lib/jobs/whoop-backfill.ts b/src/lib/jobs/whoop-backfill.ts
index aded98c8e..488ae6b1c 100644
--- a/src/lib/jobs/whoop-backfill.ts
+++ b/src/lib/jobs/whoop-backfill.ts
@@ -20,6 +20,7 @@ import { prisma } from "@/lib/db";
 import { annotate } from "@/lib/logging/context";
 import { getGlobalBoss } from "@/lib/jobs/boss-instance";
 import { integrationBackfillSourceOptions } from "@/lib/jobs/integration-backfill-admission";
+import { isReauthRequired } from "@/lib/integrations/status";
 import { syncUserWhoop } from "@/lib/whoop/sync";
 
 export const WHOOP_BACKFILL_QUEUE = "whoop-backfill";
@@ -37,15 +38,46 @@ export interface WhoopBackfillPayload {
 }
 
 /**
- * Per-user backfill handler. Runs a full-history sync for one account and
- * stamps `backfillCompletedAt` so the discovery query drops it. Idempotent:
- * the per-resource upserts are key-stable, so a re-run (e.g. a reboot mid-walk)
- * overwrites rather than duplicating.
+ * Per-user backfill handler. Runs a full-history sync for one account and stamps
+ * `backfillCompletedAt` ONLY on a clean run, so the discovery query drops it.
+ * Idempotent: the per-resource upserts are key-stable, so a re-run (e.g. a
+ * reboot mid-walk) overwrites rather than duplicating. Mirrors the landed
+ * `runFitbitBackfillForUser`.
+ *
+ * Verdict-gated: a partial hard failure (a dead token, a write failing, a
+ * fetch hard-fail) THROWS so pg-boss retries the job — stamping the marker over
+ * a partial multi-year walk would freeze the history gap forever and the
+ * configured `retryLimit` would be dead code. A connection parked at
+ * `error_reauth` is NOT clean either, but throwing against a dead grant would
+ * just burn the retry budget on the same no-op: return WITHOUT stamping — boot
+ * discovery re-offers the account after the user reconnects and a clean walk
+ * completes. `syncUserWhoop` has its own reauth short-circuit (returns
+ * `failed: true`), but the guard must still live here so a parked account
+ * RETURNS instead of throwing through three retries.
  */
 export async function runWhoopBackfillForUser(
   userId: string,
 ): Promise<{ imported: number }> {
-  const imported = await syncUserWhoop(userId, { fullSync: true });
+  if (await isReauthRequired(userId, "whoop")) {
+    annotate({
+      action: {
+        name: "whoop.backfill.skipped_reauth",
+        details: { imported: 0 },
+      },
+    });
+    return { imported: 0 };
+  }
+
+  const { imported, failed } = await syncUserWhoop(userId, { fullSync: true });
+
+  if (failed) {
+    // Surface through the pg-boss retry path (retryLimit + backoff set by
+    // `integrationBackfillSourceOptions`). If the failure parked the connection
+    // at error_reauth meanwhile, the next attempt takes the reauth return above.
+    throw new Error(
+      `whoop backfill incomplete for user ${userId} — marker not stamped`,
+    );
+  }
 
   await prisma.whoopConnection.update({
     where: { userId },
diff --git a/src/lib/nightscout/__tests__/sync.test.ts b/src/lib/nightscout/__tests__/sync.test.ts
index f9f46043a..770eb67d4 100644
--- a/src/lib/nightscout/__tests__/sync.test.ts
+++ b/src/lib/nightscout/__tests__/sync.test.ts
@@ -4,6 +4,8 @@ const {
   fetchSgvEntriesMock,
   getCredsMock,
   upsertMock,
+  findManyMock,
+  emitArrivalsMock,
   recordSuccessMock,
   recordFailureMock,
   recomputeMock,
@@ -12,6 +14,8 @@ const {
   fetchSgvEntriesMock: vi.fn(),
   getCredsMock: vi.fn(),
   upsertMock: vi.fn(),
+  findManyMock: vi.fn(),
+  emitArrivalsMock: vi.fn(),
   recordSuccessMock: vi.fn(),
   recordFailureMock: vi.fn(),
   recomputeMock: vi.fn(),
@@ -23,7 +27,11 @@ vi.mock("../credentials", () => ({
 }));
 
 vi.mock("@/lib/db", () => ({
-  prisma: { measurement: { upsert: upsertMock } },
+  prisma: { measurement: { upsert: upsertMock, findMany: findManyMock } },
+}));
+
+vi.mock("@/lib/arrivals/measurement-emit", () => ({
+  emitInsertedMeasurementArrivals: emitArrivalsMock,
 }));
 
 vi.mock("@/lib/integrations/status", async (importOriginal) => ({
@@ -63,12 +71,17 @@ beforeEach(() => {
   fetchSgvEntriesMock.mockReset();
   getCredsMock.mockReset();
   upsertMock.mockReset();
+  findManyMock.mockReset();
+  emitArrivalsMock.mockReset();
   recordSuccessMock.mockReset();
   recordFailureMock.mockReset();
   recomputeMock.mockReset();
   invalidateMock.mockReset();
   getCredsMock.mockResolvedValue(CREDS);
-  upsertMock.mockResolvedValue({});
+  upsertMock.mockResolvedValue({ id: "row" });
+  // Default: no rows pre-exist → every entry is a fresh insert.
+  findManyMock.mockResolvedValue([]);
+  emitArrivalsMock.mockResolvedValue(undefined);
   invalidateMock.mockResolvedValue(undefined);
 });
 
@@ -128,6 +141,51 @@ describe("syncUserNightscout", () => {
     expect(recordSuccessMock).toHaveBeenCalledWith("u1", "nightscout");
   });
 
+  it("N-1 — counts only fresh inserts and emits ONLY the newly-inserted rows", async () => {
+    fetchSgvEntriesMock.mockResolvedValue([ENTRY_A, ENTRY_B]);
+    // ENTRY_A already exists (a re-confirm); ENTRY_B is genuinely new.
+    findManyMock.mockResolvedValue([{ externalId: "ns:abc" }]);
+
+    const n = await syncUserNightscout("u1");
+
+    // The inflated insert+reconfirm count used to fire the reminder-satisfy
+    // trigger every tick; the honest count is the single fresh insert.
+    expect(n).toBe(1);
+    // Both rows are still written (idempotent), but only the fresh one emits.
+    expect(upsertMock).toHaveBeenCalledTimes(2);
+    expect(emitArrivalsMock).toHaveBeenCalledTimes(1);
+    const [uid, rows, source] = emitArrivalsMock.mock.calls[0]!;
+    expect(uid).toBe("u1");
+    expect(source).toBe("nightscout");
+    expect(rows).toHaveLength(1);
+    expect(rows[0]).toMatchObject({
+      type: "BLOOD_GLUCOSE",
+      measuredAt: new Date(1718000300000),
+    });
+    expect(recordSuccessMock).toHaveBeenCalledWith("u1", "nightscout");
+  });
+
+  it("N-2 — a partial row failure records a transient failure and SKIPS success", async () => {
+    fetchSgvEntriesMock.mockResolvedValue([ENTRY_A, ENTRY_B]);
+    findManyMock.mockResolvedValue([]);
+    upsertMock
+      .mockResolvedValueOnce({ id: "r1" })
+      .mockRejectedValueOnce(new Error("bad row"));
+
+    const n = await syncUserNightscout("u1");
+
+    // The one good row still landed; the tick is honest about the failed row.
+    expect(n).toBe(1);
+    expect(recordSuccessMock).not.toHaveBeenCalled();
+    expect(recordFailureMock).toHaveBeenCalledWith(
+      expect.objectContaining({
+        integration: "nightscout",
+        kind: "transient",
+        message: "1 of 2 SGV rows failed to write",
+      }),
+    );
+  });
+
   it("records a failure and rethrows when the instance is unreachable", async () => {
     fetchSgvEntriesMock.mockRejectedValue(
       new NightscoutApiError("Nightscout responded 401", 401),
diff --git a/src/lib/nightscout/sync.ts b/src/lib/nightscout/sync.ts
index 0a7ef96f7..44588d512 100644
--- a/src/lib/nightscout/sync.ts
+++ b/src/lib/nightscout/sync.ts
@@ -23,6 +23,7 @@ import { prisma } from "@/lib/db";
 import type { MeasurementType } from "@/generated/prisma/client";
 import { getEvent } from "@/lib/logging/context";
 import {
+  markSyncFailureRecorded,
   recordSyncFailure,
   recordSyncSuccess,
   toFailureKind,
@@ -33,6 +34,10 @@ import {
   collapseToTypeDayKeys,
   recomputeBucketsForMeasurement,
 } from "@/lib/rollups/measurement-rollups";
+import {
+  emitInsertedMeasurementArrivals,
+  type InsertedMeasurementArrivalRow,
+} from "@/lib/arrivals/measurement-emit";
 import { invalidateStatusInsightsForTypes } from "@/lib/insights/comprehensive-generate";
 import {
   fetchSgvEntries,
@@ -46,7 +51,12 @@ import { getUserNightscoutCredentials } from "./credentials";
  * How many recent SGV entries to pull per sync tick. A CGM emits one reading
  * every ~5 min (≈288/day); 576 covers ~48 h of catch-up so a missed hourly
  * tick (or a brief outage) still backfills on the next run without paging the
- * full instance. The far-history backfill walks larger windows separately.
+ * full instance.
+ *
+ * This ~48 h window is the ONLY history Nightscout imports: there is no
+ * far-history backfill queue, so connecting Nightscout brings in about two
+ * days of readings and every tick thereafter walks the same recent set. A
+ * deeper walk would need its own windowed-pagination queue; it is not built.
  */
 export const NIGHTSCOUT_SYNC_COUNT = 576;
 
@@ -69,6 +79,32 @@ export function redactNightscoutSecret(message: string): string {
   return message.replace(/\b(token|api-secret)=[^\s&"']+/gi, "$1=REDACTED");
 }
 
+/**
+ * Record a Nightscout sync failure on the shared `nightscout` ledger with the
+ * correct classification + HTTP code + the token STRIPPED from the message.
+ * Extracted so the poll-cohort boundary can record a future escape with the
+ * same provider-owned classification AND redaction the inline fetch catch
+ * applies — a boundary-blind recorder would persist the token-bearing URL a
+ * `SafeFetchError` embeds.
+ */
+export async function recordNightscoutSyncFailure(
+  userId: string,
+  err: unknown,
+): Promise<void> {
+  await recordSyncFailure({
+    userId,
+    integration: "nightscout",
+    kind: classifyNightscoutFailure(err),
+    message: redactNightscoutSecret(
+      err instanceof Error ? err.message : String(err),
+    ),
+    errorCode:
+      err instanceof NightscoutApiError && err.status != null
+        ? String(err.status)
+        : undefined,
+  });
+}
+
 /** Map a Nightscout HTTP status / network error onto the shared ledger kind. */
 export function classifyNightscoutFailure(err: unknown): FailureKind {
   let classification: IntegrationClassification = "transient";
@@ -86,9 +122,12 @@ export function classifyNightscoutFailure(err: unknown): FailureKind {
 }
 
 /**
- * Sync one user's recent SGV entries. Returns the count of rows written
- * (newly inserted or re-confirmed). A user with no configured instance is a
- * clean no-op (returns 0, touches no status row).
+ * Sync one user's recent SGV entries. Returns the count of rows FRESHLY
+ * INSERTED this tick (re-confirmed rows the upsert merely touched are not
+ * counted — the old insert+reconfirm total inflated the cohort's
+ * `measurements_imported` and fired the reminder-satisfy trigger every tick
+ * regardless of whether new glucose actually arrived). A user with no
+ * configured instance is a clean no-op (returns 0, touches no status row).
  */
 export async function syncUserNightscout(
   userId: string,
@@ -106,25 +145,34 @@ export async function syncUserNightscout(
       allowPrivateHost: creds.allowPrivateHost,
     });
   } catch (err) {
+    // Recorded here (token-redacted), then marked so the poll-cohort boundary
+    // does not double-record it — and never re-persists the token-bearing URL
+    // a boundary-blind recorder would.
+    await recordNightscoutSyncFailure(userId, err);
+    throw markSyncFailureRecorded(err);
+  }
+
+  const { inserted, failedRows } = await upsertNightscoutEntries(
+    userId,
+    entries,
+  );
+
+  if (failedRows > 0) {
+    // Partial write failure: keep the tick honest. `transient` because the
+    // ~48 h re-fetch window self-heals a transient DB hiccup, while a
+    // persistent malformed-row failure now accrues visible strikes instead of
+    // being invisibly reset by a success stamp. Do NOT stamp success.
     await recordSyncFailure({
       userId,
       integration: "nightscout",
-      kind: classifyNightscoutFailure(err),
-      message: redactNightscoutSecret(
-        err instanceof Error ? err.message : String(err),
-      ),
-      errorCode:
-        err instanceof NightscoutApiError && err.status != null
-          ? String(err.status)
-          : undefined,
+      kind: "transient",
+      message: `${failedRows} of ${entries.length} SGV rows failed to write`,
     });
-    throw err;
+    return inserted;
   }
 
-  const imported = await upsertNightscoutEntries(userId, entries);
-
   await recordSyncSuccess(userId, "nightscout");
-  return imported;
+  return inserted;
 }
 
 /**
@@ -132,38 +180,71 @@ export async function syncUserNightscout(
  * rollup tier + invalidate status-insight caches once at the end (mirrors the
  * Withings / WHOOP sync tail). First-write-wins: the `update` branch is empty
  * so a re-sync of the same reading is a no-op rather than a rewrite. Best-effort
- * on the per-row write + the rollup fold — one bad row never aborts the pass.
+ * on the per-row write + the rollup fold — one bad row never aborts the pass,
+ * and the count of failed rows is returned so the caller can surface a partial
+ * write failure instead of stamping success over it.
+ *
+ * Returns `inserted` (rows whose key was absent before this pass — the honest
+ * "new readings" count that also drives the arrival emit) and `failedRows`.
  */
 export async function upsertNightscoutEntries(
   userId: string,
   entries: ParsedSgvEntry[],
-): Promise<number> {
-  if (entries.length === 0) return 0;
+): Promise<{ inserted: number; failedRows: number }> {
+  if (entries.length === 0) return { inserted: 0, failedRows: 0 };
 
   const type = "BLOOD_GLUCOSE" as MeasurementType;
-  let imported = 0;
+  const mapped = entries.map((entry) => mapSgvEntryToMeasurement(entry));
+
+  // Probe which keys already exist so a re-confirmed reading (the upsert's
+  // no-op update branch) is not miscounted as a fresh import and the arrival
+  // spine emits ONLY the genuinely-new rows. Cohort passes are sequential per
+  // user, so no concurrent insert races this probe. A probe failure degrades
+  // to "treat every row as fresh" — the rollup fold + count self-correct on
+  // the next tick.
+  const existingKeys = new Set<string>();
+  try {
+    const existing = await prisma.measurement.findMany({
+      where: {
+        userId,
+        type,
+        source: "NIGHTSCOUT",
+        externalId: { in: mapped.map((m) => m.externalId) },
+      },
+      select: { externalId: true },
+    });
+    for (const row of existing) {
+      if (row.externalId) existingKeys.add(row.externalId);
+    }
+  } catch (err) {
+    getEvent()?.addWarning(
+      `nightscout: insert-probe failed for ${userId}: ${err}`,
+    );
+  }
+
+  let failedRows = 0;
+  const insertedRows: InsertedMeasurementArrivalRow[] = [];
   const touched: Array<{ type: MeasurementType; measuredAt: Date }> = [];
 
-  for (const entry of entries) {
-    const mapped = mapSgvEntryToMeasurement(entry);
+  for (const m of mapped) {
     try {
-      await prisma.measurement.upsert({
+      const row = await prisma.measurement.upsert({
         where: {
           userId_type_source_externalId: {
             userId,
             type,
             source: "NIGHTSCOUT",
-            externalId: mapped.externalId,
+            externalId: m.externalId,
           },
         },
         create: {
           userId,
           type,
           source: "NIGHTSCOUT",
-          value: mapped.value,
-          unit: mapped.unit,
-          measuredAt: mapped.measuredAt,
-          externalId: mapped.externalId,
+          value: m.value,
+          unit: m.unit,
+          measuredAt: m.measuredAt,
+          externalId: m.externalId,
         },
         // First-write-wins: a CGM sample is immutable, so a re-sync of the
         // same reading must not rewrite the stored value or measuredAt.
@@ -172,16 +253,32 @@ export async function upsertNightscoutEntries(
         // truth for its own rows, so a re-synced reading brings the row
         // back (mirrors Google / Fitbit).
         update: { deletedAt: null },
+        select: { id: true },
       });
-      touched.push({ type, measuredAt: mapped.measuredAt });
-      imported++;
+      touched.push({ type, measuredAt: m.measuredAt });
+      if (!existingKeys.has(m.externalId)) {
+        insertedRows.push({ type, measuredAt: m.measuredAt, id: row.id });
+      }
     } catch (err) {
       getEvent()?.addWarning(
         `nightscout: failed to upsert measurement: ${err}`,
       );
+      failedRows++;
     }
   }
 
+  // Spine parity with every other measurement writer: emit at most one arrival
+  // per supported kind for the rows freshly inserted. BLOOD_GLUCOSE is not yet
+  // an arrival kind (`ARRIVAL_MEASUREMENT_KIND`), so this is behaviourally
+  // inert for glucose today — it removes Nightscout as the spine's odd one out
+  // and lights up automatically once a `glucose` arrival kind + its consuming
+  // surface land in a later release.
+  void emitInsertedMeasurementArrivals(
+    userId,
+    insertedRows,
+    "nightscout",
+  ).catch(() => {});
+
   try {
     const keys = collapseToTypeDayKeys(touched);
     for (const k of keys) {
@@ -201,5 +298,5 @@ export async function upsertNightscoutEntries(
     );
   }
 
-  return imported;
+  return { inserted: insertedRows.length, failedRows };
 }
diff --git a/src/lib/oura/__tests__/sync.test.ts b/src/lib/oura/__tests__/sync.test.ts
index d59602a77..798947ed9 100644
--- a/src/lib/oura/__tests__/sync.test.ts
+++ b/src/lib/oura/__tests__/sync.test.ts
@@ -114,6 +114,7 @@ vi.mock("../client", async (importOriginal) => {
 
 import { syncUserOura, upsertOuraMeasurements } from "../sync";
 import { OuraApiError } from "../response-classifier";
+import { isSyncFailureRecorded } from "@/lib/integrations/status";
 
 const CONN = {
   accessToken: "acc",
@@ -284,13 +285,39 @@ describe("syncUserOura", () => {
         upstreamError: "invalid_grant",
       }),
     );
-    await expect(syncUserOura("u1")).rejects.toBeInstanceOf(OuraApiError);
+    const err = await syncUserOura("u1").catch((e) => e);
+    expect(err).toBeInstanceOf(OuraApiError);
+    // Recorded at the source AND marked, so the poll-cohort boundary does not
+    // record it a second time.
+    expect(isSyncFailureRecorded(err)).toBe(true);
+    expect(recordFailureMock).toHaveBeenCalledTimes(1);
     expect(recordFailureMock).toHaveBeenCalledWith(
       expect.objectContaining({ integration: "oura", kind: "reauth_required" }),
     );
     expect(recordSuccessMock).not.toHaveBeenCalled();
   });
 
+  it("leaves a write-path failure UNMARKED so the cohort boundary records it once", async () => {
+    // The `upsertOuraMeasurements` transaction throw escapes `syncUserOura`
+    // uncaught: no source-site record, no mark — the poll-cohort boundary is
+    // what records it (exactly once).
+    getConnMock.mockResolvedValue(CONN);
+    fetchReadinessMock.mockResolvedValue([
+      { id: "r1", day: "2026-06-10", score: 71 },
+    ]);
+    reconcileMock.mockResolvedValue({
+      status: "failed",
+      reason: "db_error",
+      error: new Error("write boom"),
+    });
+
+    const err = await syncUserOura("u1").catch((e) => e);
+    expect(err).toBeInstanceOf(Error);
+    expect(isSyncFailureRecorded(err)).toBe(false);
+    expect(recordFailureMock).not.toHaveBeenCalled();
+    expect(recordSuccessMock).not.toHaveBeenCalled();
+  });
+
   it("keeps a nap and the main sleep distinct via record-scoped externalIds (B2)", async () => {
     getConnMock.mockResolvedValue(CONN);
     // Two sleep records on the same day: a main sleep + a nap.
diff --git a/src/lib/oura/sync.ts b/src/lib/oura/sync.ts
index 779cf1bdf..9ed4bc39a 100644
--- a/src/lib/oura/sync.ts
+++ b/src/lib/oura/sync.ts
@@ -37,6 +37,7 @@ import { prisma } from "@/lib/db";
 import type { MeasurementType } from "@/generated/prisma/client";
 import { getEvent } from "@/lib/logging/context";
 import {
+  markSyncFailureRecorded,
   recordSyncFailure,
   recordSyncSuccess,
   toFailureKind,
@@ -97,6 +98,28 @@ export function classifyOuraFailure(err: unknown): FailureKind {
   return toFailureKind(classifyOuraError(err));
 }
 
+/**
+ * Record a whole-connection Oura sync failure on the shared `oura` ledger with
+ * the correct classification + HTTP code. Extracted so the poll-cohort boundary
+ * can record a future escape with the SAME provider-owned classification the
+ * inline catch already applies.
+ */
+export async function recordOuraSyncFailure(
+  userId: string,
+  err: unknown,
+): Promise<void> {
+  await recordSyncFailure({
+    userId,
+    integration: "oura",
+    kind: classifyOuraFailure(err),
+    message: err instanceof Error ? err.message : String(err),
+    errorCode:
+      err instanceof OuraApiError && err.httpStatus != null
+        ? String(err.httpStatus)
+        : undefined,
+  });
+}
+
 function ymd(d: Date): string {
   return d.toISOString().slice(0, 10);
 }
@@ -355,17 +378,10 @@ export async function syncUserOura(
   } catch (err) {
     // Only a whole-connection failure (a failed token refresh → reauth) reaches
     // here now; per-collection failures are captured on `result.failures`.
-    await recordSyncFailure({
-      userId,
-      integration: "oura",
-      kind: classifyOuraFailure(err),
-      message: err instanceof Error ? err.message : String(err),
-      errorCode:
-        err instanceof OuraApiError && err.httpStatus != null
-          ? String(err.httpStatus)
-          : undefined,
-    });
-    throw err;
+    // Recorded here, then marked so the poll-cohort boundary does not
+    // double-record it when it surfaces there.
+    await recordOuraSyncFailure(userId, err);
+    throw markSyncFailureRecorded(err);
   }
 
   // Clear whatever an earlier scoring left under the re-fetched sleep records
diff --git a/src/lib/polar/__tests__/sync.test.ts b/src/lib/polar/__tests__/sync.test.ts
index 9b717ee72..71aace68c 100644
--- a/src/lib/polar/__tests__/sync.test.ts
+++ b/src/lib/polar/__tests__/sync.test.ts
@@ -92,6 +92,7 @@ vi.mock("../client", async (importOriginal) => {
 });
 
 import { syncUserPolar, upsertPolarMeasurements } from "../sync";
+import { isSyncFailureRecorded } from "@/lib/integrations/status";
 import { PolarApiError } from "../response-classifier";
 
 const CONN = { accessToken: "tok", polarUserId: "42" };
@@ -340,7 +341,12 @@ describe("syncUserPolar", () => {
         reason: "http_401",
       }),
     );
-    await expect(syncUserPolar("u1")).rejects.toBeInstanceOf(PolarApiError);
+    const err = await syncUserPolar("u1").catch((e) => e);
+    expect(err).toBeInstanceOf(PolarApiError);
+    // Recorded at the source AND marked (the legs wrapper rethrows the marked
+    // error), so the poll-cohort boundary does not double-record it.
+    expect(isSyncFailureRecorded(err)).toBe(true);
+    expect(recordFailureMock).toHaveBeenCalledTimes(1);
     expect(recordFailureMock).toHaveBeenCalledWith(
       expect.objectContaining({
         userId: "u1",
@@ -351,6 +357,27 @@ describe("syncUserPolar", () => {
     );
     expect(recordSuccessMock).not.toHaveBeenCalled();
   });
+
+  it("leaves a write-path failure UNMARKED so the cohort boundary records it once", async () => {
+    // The `upsertPolarMeasurements` transaction throw escapes `syncUserPolar`
+    // uncaught: no source-site record, no mark — the poll-cohort boundary is
+    // what records it (exactly once).
+    getConnMock.mockResolvedValue(CONN);
+    fetchRechargesMock.mockResolvedValue([
+      { date: "2026-06-10", nightly_recharge_status: 6 },
+    ]);
+    reconcileMock.mockReset().mockResolvedValue({
+      status: "failed",
+      reason: "db_error",
+      error: new Error("write boom"),
+    });
+
+    const err = await syncUserPolar("u1").catch((e) => e);
+    expect(err).toBeInstanceOf(Error);
+    expect(isSyncFailureRecorded(err)).toBe(false);
+    expect(recordFailureMock).not.toHaveBeenCalled();
+    expect(recordSuccessMock).not.toHaveBeenCalled();
+  });
 });
 
 describe("upsertPolarMeasurements — exact insertion results", () => {
diff --git a/src/lib/polar/sync-workouts.ts b/src/lib/polar/sync-workouts.ts
index 5893e31d8..0f7e942c0 100644
--- a/src/lib/polar/sync-workouts.ts
+++ b/src/lib/polar/sync-workouts.ts
@@ -31,7 +31,11 @@
 import { prisma } from "@/lib/db";
 import { emitInsertedWorkoutArrival } from "@/lib/arrivals/workout-emit";
 import { annotate, getEvent } from "@/lib/logging/context";
-import { recordSyncFailure, toFailureKind } from "@/lib/integrations/status";
+import {
+  markSyncFailureRecorded,
+  recordSyncFailure,
+  toFailureKind,
+} from "@/lib/integrations/status";
 import { fetchExercises, mapExercise, type PolarWorkoutRow } from "./client";
 import { getPolarConnection } from "./credentials";
 import { PolarApiError, classifyPolarError } from "./response-classifier";
@@ -82,7 +86,7 @@ export async function syncUserPolarWorkouts(userId: string): Promise<number> {
     }
   } catch (err) {
     await recordPolarWorkoutFailure(userId, err);
-    throw err;
+    throw markSyncFailureRecorded(err);
   }
 
   let imported: number;
@@ -90,7 +94,7 @@ export async function syncUserPolarWorkouts(userId: string): Promise<number> {
     imported = await upsertPolarWorkouts(userId, rows);
   } catch (err) {
     await recordPolarWorkoutFailure(userId, err);
-    throw err;
+    throw markSyncFailureRecorded(err);
   }
 
   return imported;
diff --git a/src/lib/polar/sync.ts b/src/lib/polar/sync.ts
index f43c184d9..7878c4475 100644
--- a/src/lib/polar/sync.ts
+++ b/src/lib/polar/sync.ts
@@ -25,6 +25,7 @@ import { prisma } from "@/lib/db";
 import type { MeasurementType } from "@/generated/prisma/client";
 import { getEvent } from "@/lib/logging/context";
 import {
+  markSyncFailureRecorded,
   recordSyncFailure,
   recordSyncSuccess,
   toFailureKind,
@@ -69,6 +70,28 @@ export function classifyPolarFailure(err: unknown): FailureKind {
   return toFailureKind(classifyPolarError(err));
 }
 
+/**
+ * Record a Polar vitals-leg sync failure on the shared `polar` ledger with the
+ * correct classification + HTTP code. Extracted so the poll-cohort boundary can
+ * record a future escape with the SAME provider-owned classification the inline
+ * catch already applies.
+ */
+export async function recordPolarSyncFailure(
+  userId: string,
+  err: unknown,
+): Promise<void> {
+  await recordSyncFailure({
+    userId,
+    integration: "polar",
+    kind: classifyPolarFailure(err),
+    message: err instanceof Error ? err.message : String(err),
+    errorCode:
+      err instanceof PolarApiError && err.httpStatus != null
+        ? String(err.httpStatus)
+        : undefined,
+  });
+}
+
 /** One mapped reading with its `externalId` resolved. */
 export interface PolarMeasurementUpsert {
   type: string;
@@ -151,17 +174,10 @@ export async function syncUserPolar(userId: string): Promise<number> {
       readings.push(...toUpsert(mapSpo2(t), "spo2"));
     }
   } catch (err) {
-    await recordSyncFailure({
-      userId,
-      integration: "polar",
-      kind: classifyPolarFailure(err),
-      message: err instanceof Error ? err.message : String(err),
-      errorCode:
-        err instanceof PolarApiError && err.httpStatus != null
-          ? String(err.httpStatus)
-          : undefined,
-    });
-    throw err;
+    // Recorded here, then marked so the poll-cohort boundary does not
+    // double-record it when the legs wrapper rethrows it there.
+    await recordPolarSyncFailure(userId, err);
+    throw markSyncFailureRecorded(err);
   }
 
   // Clear whatever an earlier scoring left under the re-fetched nights before
diff --git a/src/lib/strava/__tests__/sync-cursor-durability.test.ts b/src/lib/strava/__tests__/sync-cursor-durability.test.ts
index 18019f19a..dc71edf55 100644
--- a/src/lib/strava/__tests__/sync-cursor-durability.test.ts
+++ b/src/lib/strava/__tests__/sync-cursor-durability.test.ts
@@ -39,6 +39,7 @@ vi.mock("@/lib/integrations/status", () => ({
   recordSyncFailure: mocks.recordSyncFailure,
   recordSyncSuccess: mocks.recordSyncSuccess,
   toFailureKind: vi.fn(() => "transient"),
+  markSyncFailureRecorded: <T>(err: T) => err,
 }));
 vi.mock("../credentials", () => ({
   getStravaConnection: mocks.getStravaConnection,
diff --git a/src/lib/strava/sync.ts b/src/lib/strava/sync.ts
index e416407c4..346850464 100644
--- a/src/lib/strava/sync.ts
+++ b/src/lib/strava/sync.ts
@@ -27,6 +27,7 @@ import { prisma } from "@/lib/db";
 import { emitInsertedWorkoutArrival } from "@/lib/arrivals/workout-emit";
 import { annotate, getEvent } from "@/lib/logging/context";
 import {
+  markSyncFailureRecorded,
   recordSyncFailure,
   recordSyncSuccess,
   toFailureKind,
@@ -68,7 +69,7 @@ export function classifyStravaFailure(err: unknown): FailureKind {
   return toFailureKind(classifyStravaError(err));
 }
 
-async function recordStravaFailure(
+export async function recordStravaFailure(
   userId: string,
   err: unknown,
 ): Promise<void> {
@@ -215,7 +216,7 @@ export async function syncUserStrava(
     }
   } catch (err) {
     await recordStravaFailure(userId, err);
-    throw err;
+    throw markSyncFailureRecorded(err);
   }
 
   let imported: number;
@@ -239,7 +240,7 @@ export async function syncUserStrava(
     }
   } catch (err) {
     await recordStravaFailure(userId, err);
-    throw err;
+    throw markSyncFailureRecorded(err);
   }
 
   await recordSyncSuccess(userId, "strava");
diff --git a/src/lib/whoop/__tests__/sync-cycle-overlap.test.ts b/src/lib/whoop/__tests__/sync-cycle-overlap.test.ts
new file mode 100644
index 000000000..27b865782
--- /dev/null
+++ b/src/lib/whoop/__tests__/sync-cycle-overlap.test.ts
@@ -0,0 +1,83 @@
+/**
+ * Q8 — WHOOP cycle ingest used the narrow 1 h default overlap while workout /
+ * recovery / sleep use the 7-day re-score overlap. A cycle re-scored through the
+ * day (or fetched just after the cursor stepped past it) then fell before the
+ * incremental `start` and its final value was never re-fetched. This pins cycle
+ * onto the SAME overlap the other collections use (the upsert is idempotent).
+ */
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const fetchCycles = vi.fn();
+
+vi.mock("../client", () => ({
+  fetchCycles: (...a: unknown[]) => fetchCycles(...a),
+  mapCycle: () => [],
+}));
+
+const getValidToken = vi.fn();
+const markResourceSynced = vi.fn();
+const upsertWhoopMeasurements = vi.fn();
+vi.mock("../sync-core", async () => {
+  const actual =
+    await vi.importActual<typeof import("../sync-core")>("../sync-core");
+  return {
+    ...actual,
+    getValidToken: (...a: unknown[]) => getValidToken(...a),
+    markResourceSynced: (...a: unknown[]) => markResourceSynced(...a),
+    upsertWhoopMeasurements: (...a: unknown[]) => upsertWhoopMeasurements(...a),
+  };
+});
+
+const whoopConnectionFindUnique = vi.fn();
+vi.mock("@/lib/db", () => ({
+  prisma: {
+    whoopConnection: {
+      findUnique: (...a: unknown[]) => whoopConnectionFindUnique(...a),
+    },
+  },
+}));
+
+import { syncUserCycle } from "../sync-cycle";
+import {
+  WHOOP_FULL_SYNC_ANCHOR,
+  WHOOP_RECOVERY_SLEEP_OVERLAP_MS,
+} from "../sync-core";
+
+const LAST_SYNCED = new Date("2026-06-10T12:00:00.000Z");
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  getValidToken.mockResolvedValue({
+    accessToken: "tok",
+    connection: { id: "c1", whoopUserId: "w1" },
+  });
+  whoopConnectionFindUnique.mockResolvedValue({
+    lastSyncedAt: LAST_SYNCED,
+    resourceCursors: null,
+  });
+  markResourceSynced.mockResolvedValue(undefined);
+  upsertWhoopMeasurements.mockResolvedValue(0);
+  fetchCycles.mockResolvedValue([]);
+});
+
+describe("syncUserCycle — 7-day re-score overlap window", () => {
+  it("fetches from lastSyncedAt minus the 7-day overlap, not 1 h", async () => {
+    await syncUserCycle("user-1");
+
+    expect(fetchCycles).toHaveBeenCalledTimes(1);
+    const arg = fetchCycles.mock.calls[0]![1] as { start?: Date };
+    expect(arg.start?.getTime()).toBe(
+      LAST_SYNCED.getTime() - WHOOP_RECOVERY_SLEEP_OVERLAP_MS,
+    );
+    // A cycle still settling 6 h after the cursor is inside the fetch range;
+    // under the old 1 h overlap it would be missed.
+    const sixHoursBefore = LAST_SYNCED.getTime() - 6 * 60 * 60 * 1000;
+    expect(arg.start!.getTime()).toBeLessThanOrEqual(sixHoursBefore);
+  });
+
+  it("fullSync anchors at the deep-history anchor, not the cursor", async () => {
+    await syncUserCycle("user-1", { fullSync: true });
+    const arg = fetchCycles.mock.calls[0]![1] as { start?: Date };
+    expect(arg.start).toEqual(WHOOP_FULL_SYNC_ANCHOR);
+  });
+});
diff --git a/src/lib/whoop/__tests__/sync-dead-token.test.ts b/src/lib/whoop/__tests__/sync-dead-token.test.ts
new file mode 100644
index 000000000..3065f74a2
--- /dev/null
+++ b/src/lib/whoop/__tests__/sync-dead-token.test.ts
@@ -0,0 +1,277 @@
+/**
+ * WH-1 — pins the dead-token verdict for WHOOP, the parity mirror of
+ * `fitbit/__tests__/sync-dead-token.test.ts`.
+ *
+ * `getValidToken`'s three null-return paths (credentials missing, refresh
+ * failure inside the advisory-lock transaction, and the in-lock vanished
+ * connection) must register on the cycle's hard-fail ledger, and a cycle whose
+ * token is dead must NOT stamp `recordSyncSuccess`. Otherwise every resource
+ * returns 0 without failures, the cycle reads as clean, `recordSyncSuccess`
+ * un-parks `error_reauth`, and the hourly cohort hammers the dead refresh token
+ * forever while `lastSyncedAt` advances past real data.
+ *
+ * Includes the WHOOP-specific pin Fitbit has no twin for: the per-resource
+ * driver `syncWhoopResourceWithStatus` (the dominant hourly-cron path) must
+ * also refuse the success stamp when a hard failure is noted inside `run`.
+ */
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const {
+  recordSyncFailureMock,
+  recordSyncSuccessMock,
+  isReauthRequiredMock,
+  prismaMock,
+  getUserWhoopCredentialsMock,
+  refreshAccessTokenMock,
+  resourceFake,
+} = vi.hoisted(() => ({
+  recordSyncFailureMock: vi.fn(async () => {}),
+  recordSyncSuccessMock: vi.fn(async () => {}),
+  isReauthRequiredMock: vi.fn(async () => false),
+  prismaMock: {
+    whoopConnection: {
+      findUnique: vi.fn(),
+      update: vi.fn(async () => ({})),
+    },
+    $transaction: vi.fn(),
+  },
+  getUserWhoopCredentialsMock: vi.fn(async (): Promise<unknown> => null),
+  refreshAccessTokenMock: vi.fn(),
+  // The dead-token cycle test drives the real `syncUserWhoop`; each resource
+  // module resolves the token first — exactly what the real leaves do — so the
+  // ledger registration happens inside the cycle's ALS scope.
+  resourceFake: async (userId: string): Promise<number> => {
+    const { getValidToken } = await import("../sync-core");
+    return (await getValidToken(userId)) ? 1 : 0;
+  },
+}));
+
+vi.mock("@/lib/db", () => ({ prisma: prismaMock }));
+vi.mock("@/lib/crypto", () => ({
+  encrypt: (s: string) => `enc(${s})`,
+  decrypt: (s: string) => s.replace(/^enc\(|\)$/g, ""),
+}));
+vi.mock("@/lib/integrations/status", () => ({
+  isReauthRequired: isReauthRequiredMock,
+  recordSyncFailure: recordSyncFailureMock,
+  recordSyncSuccess: recordSyncSuccessMock,
+  isSyncFailureRecorded: () => false,
+  markSyncFailureRecorded: <T>(err: T) => err,
+}));
+vi.mock("@/lib/integrations/oauth-refresh", () => ({
+  acquireProviderTokenRefreshLock: vi.fn(async () => {}),
+  PROVIDER_REFRESH_TRANSACTION_OPTIONS: { maxWait: 10_000, timeout: 60_000 },
+}));
+vi.mock("@/lib/measurements/reconcile-external-measurement", () => ({
+  reconcileExternalMeasurement: vi.fn(),
+  MeasurementReconciliationError: class extends Error {},
+}));
+vi.mock("@/lib/rollups/measurement-rollups", () => ({
+  collapseToTypeDayKeys: vi.fn(() => []),
+  recomputeBucketsForMeasurement: vi.fn(async () => {}),
+}));
+vi.mock("@/lib/insights/comprehensive-generate", () => ({
+  invalidateStatusInsightsForTypes: vi.fn(async () => {}),
+}));
+vi.mock("@/lib/arrivals/measurement-emit", () => ({
+  emitInsertedMeasurementArrivals: vi.fn(async () => {}),
+}));
+vi.mock("@/lib/logging/context", () => ({
+  getEvent: () => null,
+  annotate: () => {},
+}));
+vi.mock("../credentials", () => ({
+  getUserWhoopCredentials: getUserWhoopCredentialsMock,
+}));
+vi.mock("../client", async (orig) => {
+  const actual = await orig<typeof import("../client")>();
+  return { ...actual, refreshAccessToken: refreshAccessTokenMock };
+});
+
+// Each resource resolves the token first (the ledger-registration seam).
+vi.mock("../sync-recovery", () => ({ syncUserRecovery: resourceFake }));
+vi.mock("../sync-sleep", () => ({ syncUserSleep: resourceFake }));
+vi.mock("../sync-cycle", () => ({ syncUserCycle: resourceFake }));
+vi.mock("../sync-workout", () => ({ syncUserWorkout: resourceFake }));
+vi.mock("../sync-body", () => ({ syncUserBody: resourceFake }));
+
+import {
+  WHOOP_TOKEN_HARD_FAIL,
+  getValidToken,
+  hardFailStorage,
+  noteHardFailure,
+  syncWhoopResourceWithStatus,
+} from "../sync-core";
+import { syncUserWhoop } from "../sync";
+import { WhoopApiError } from "../response-classifier";
+
+/** Run `fn` inside a fresh hard-fail ledger scope and return its failures. */
+async function withLedger<T>(
+  fn: () => Promise<T>,
+): Promise<{ result: T; failures: string[] }> {
+  const tracker = { failures: [] as string[] };
+  const result = await hardFailStorage.run(tracker, fn);
+  return { result, failures: tracker.failures };
+}
+
+/** A connection whose access token is inside the 5-min refresh buffer. */
+const EXPIRED_CONNECTION = {
+  id: "conn-1",
+  whoopUserId: "wu-1",
+  accessToken: "enc(access)",
+  refreshToken: "enc(refresh)",
+  tokenExpiresAt: new Date(Date.now() - 60_000),
+  lastSyncedAt: new Date("2026-07-01T00:00:00.000Z"),
+};
+
+const CREDS = { clientId: "id", clientSecret: "secret" };
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  isReauthRequiredMock.mockResolvedValue(false);
+  prismaMock.whoopConnection.findUnique.mockReset();
+  prismaMock.whoopConnection.update.mockReset().mockResolvedValue({});
+  getUserWhoopCredentialsMock.mockReset().mockResolvedValue(null);
+  refreshAccessTokenMock.mockReset();
+  // The advisory-lock transaction runs its callback against the same mock.
+  prismaMock.$transaction
+    .mockReset()
+    .mockImplementation(async (run: (tx: unknown) => unknown) =>
+      run(prismaMock),
+    );
+});
+
+describe("getValidToken — dead-token cycle verdict", () => {
+  it("registers the credentials-missing path on the hard-fail ledger", async () => {
+    prismaMock.whoopConnection.findUnique.mockResolvedValue(
+      EXPIRED_CONNECTION as never,
+    );
+    getUserWhoopCredentialsMock.mockResolvedValue(null);
+
+    const { result, failures } = await withLedger(() =>
+      getValidToken("user-1"),
+    );
+
+    expect(result).toBeNull();
+    expect(failures).toEqual([WHOOP_TOKEN_HARD_FAIL]);
+    expect(recordSyncFailureMock).toHaveBeenCalledWith(
+      expect.objectContaining({
+        integration: "whoop",
+        kind: "reauth_required",
+        errorCode: "credentials_missing",
+      }),
+    );
+  });
+
+  it("registers a refresh failure on the hard-fail ledger", async () => {
+    prismaMock.whoopConnection.findUnique.mockResolvedValue(
+      EXPIRED_CONNECTION as never,
+    );
+    getUserWhoopCredentialsMock.mockResolvedValue(CREDS);
+    refreshAccessTokenMock.mockRejectedValue(
+      new WhoopApiError({
+        verb: "refreshToken",
+        classification: "reauth_required",
+        httpStatus: 401,
+        reason: "invalid_grant",
+      }),
+    );
+
+    const { result, failures } = await withLedger(() =>
+      getValidToken("user-1"),
+    );
+
+    expect(result).toBeNull();
+    expect(failures).toEqual([WHOOP_TOKEN_HARD_FAIL]);
+    expect(recordSyncFailureMock).toHaveBeenCalledWith(
+      expect.objectContaining({
+        integration: "whoop",
+        kind: "reauth_required",
+      }),
+    );
+  });
+
+  it("registers an in-lock vanished connection on the ledger", async () => {
+    // The connection was deleted between the first read and the in-lock re-read
+    // (disconnect / webhook race).
+    prismaMock.whoopConnection.findUnique
+      .mockResolvedValueOnce(EXPIRED_CONNECTION as never) // initial read
+      .mockResolvedValueOnce(null as never); // in-lock re-read: row gone
+    getUserWhoopCredentialsMock.mockResolvedValue(CREDS);
+
+    const { result, failures } = await withLedger(() =>
+      getValidToken("user-1"),
+    );
+
+    expect(result).toBeNull();
+    expect(failures).toEqual([WHOOP_TOKEN_HARD_FAIL]);
+    expect(refreshAccessTokenMock).not.toHaveBeenCalled();
+  });
+
+  it("a successful refresh leaves the ledger empty", async () => {
+    // Guard against over-failing: a healthy refresh must not touch the ledger.
+    prismaMock.whoopConnection.findUnique.mockResolvedValue(
+      EXPIRED_CONNECTION as never,
+    );
+    getUserWhoopCredentialsMock.mockResolvedValue(CREDS);
+    refreshAccessTokenMock.mockResolvedValue({
+      access_token: "new-access",
+      refresh_token: "rotated-refresh",
+      expires_in: 3600,
+    });
+
+    const { result, failures } = await withLedger(() =>
+      getValidToken("user-1"),
+    );
+
+    expect(result?.accessToken).toBe("new-access");
+    expect(failures).toEqual([]);
+  });
+});
+
+describe("syncUserWhoop — dead-token cycle refuses the success stamp", () => {
+  it("a dead-token cycle returns { imported: 0, failed: true } and never stamps success", async () => {
+    // Every resource resolves the token; the refresh fails each time — before
+    // the ledger fix the cycle read as CLEAN (all resources returned 0 without
+    // throwing), stamped success, and un-parked error_reauth.
+    prismaMock.whoopConnection.findUnique.mockResolvedValue(
+      EXPIRED_CONNECTION as never,
+    );
+    getUserWhoopCredentialsMock.mockResolvedValue(CREDS);
+    refreshAccessTokenMock.mockRejectedValue(
+      new WhoopApiError({
+        verb: "refreshToken",
+        classification: "reauth_required",
+        httpStatus: 401,
+        reason: "invalid_grant",
+      }),
+    );
+
+    const res = await syncUserWhoop("user-1");
+
+    expect(res).toEqual({ imported: 0, failed: true });
+    expect(recordSyncSuccessMock).not.toHaveBeenCalled();
+  });
+});
+
+describe("syncWhoopResourceWithStatus — dominant per-resource cron path", () => {
+  it("does NOT stamp success when a hard failure is noted inside run", async () => {
+    // The hourly-cron arm Fitbit has no twin for: a dead token noted by
+    // `getValidToken` inside `run` must block the per-resource success stamp,
+    // or the release is inert on the path that runs most often.
+    const imported = await syncWhoopResourceWithStatus("user-1", async () => {
+      noteHardFailure(WHOOP_TOKEN_HARD_FAIL);
+      return 0;
+    });
+
+    expect(imported).toBe(0);
+    expect(recordSyncSuccessMock).not.toHaveBeenCalled();
+  });
+
+  it("stamps success on a clean per-resource run (no hard failure)", async () => {
+    const imported = await syncWhoopResourceWithStatus("user-1", async () => 3);
+
+    expect(imported).toBe(3);
+    expect(recordSyncSuccessMock).toHaveBeenCalledWith("user-1", "whoop");
+  });
+});
diff --git a/src/lib/whoop/__tests__/sync-user-whoop.test.ts b/src/lib/whoop/__tests__/sync-user-whoop.test.ts
index a1ebab5b9..2c5fcfbdc 100644
--- a/src/lib/whoop/__tests__/sync-user-whoop.test.ts
+++ b/src/lib/whoop/__tests__/sync-user-whoop.test.ts
@@ -46,6 +46,8 @@ vi.mock("@/lib/integrations/status", () => ({
   recordSyncFailure: (...a: unknown[]) => recordSyncFailure(...a),
   recordSyncSuccess: (...a: unknown[]) => recordSyncSuccess(...a),
   isReauthRequired: (...a: unknown[]) => isReauthRequired(...a),
+  isSyncFailureRecorded: () => false,
+  markSyncFailureRecorded: <T>(err: T) => err,
 }));
 vi.mock("@/lib/rollups/measurement-rollups", () => ({
   collapseToTypeDayKeys: () => [],
@@ -109,7 +111,7 @@ describe("syncUserWhoop — all-403 looks-healthy guard", () => {
       fn.mockImplementation(softSkip403);
     }
 
-    const total = await syncUserWhoop("user1");
+    const { imported: total } = await syncUserWhoop("user1");
 
     expect(total).toBe(0);
     expect(recordSyncSuccess).not.toHaveBeenCalled();
@@ -125,7 +127,7 @@ describe("syncUserWhoop — all-403 looks-healthy guard", () => {
     syncUserWorkout.mockImplementation(softSkip403);
     syncUserBody.mockImplementation(softSkip403);
 
-    const total = await syncUserWhoop("user1");
+    const { imported: total } = await syncUserWhoop("user1");
 
     expect(total).toBe(3);
     expect(recordSyncSuccess).toHaveBeenCalledWith("user1", "whoop");
@@ -138,7 +140,7 @@ describe("syncUserWhoop — all-403 looks-healthy guard", () => {
     syncUserWorkout.mockResolvedValue(0);
     syncUserBody.mockResolvedValue(0);
 
-    const total = await syncUserWhoop("user1");
+    const { imported: total } = await syncUserWhoop("user1");
 
     expect(total).toBe(3);
     expect(recordSyncSuccess).toHaveBeenCalledWith("user1", "whoop");
@@ -155,7 +157,7 @@ describe("syncUserWhoop — all-403 looks-healthy guard", () => {
       fn.mockResolvedValue(0);
     }
 
-    const total = await syncUserWhoop("user1");
+    const { imported: total } = await syncUserWhoop("user1");
 
     expect(total).toBe(0);
     // No collection was 403'd → this is a genuine "nothing changed" tick.
@@ -165,7 +167,7 @@ describe("syncUserWhoop — all-403 looks-healthy guard", () => {
   it("short-circuits without stamping success when parked at error_reauth", async () => {
     isReauthRequired.mockResolvedValue(true);
 
-    const total = await syncUserWhoop("user1");
+    const { imported: total } = await syncUserWhoop("user1");
 
     expect(total).toBe(0);
     expect(recordSyncSuccess).not.toHaveBeenCalled();
diff --git a/src/lib/whoop/sync-core.ts b/src/lib/whoop/sync-core.ts
index 9c89cdf36..dc54db379 100644
--- a/src/lib/whoop/sync-core.ts
+++ b/src/lib/whoop/sync-core.ts
@@ -30,6 +30,7 @@ import type { MeasurementType } from "@/generated/prisma/client";
 import { encrypt, decrypt } from "@/lib/crypto";
 import { getEvent } from "@/lib/logging/context";
 import {
+  markSyncFailureRecorded,
   recordSyncFailure,
   recordSyncSuccess,
   type FailureKind,
@@ -97,6 +98,42 @@ export async function runWithWhoopSoftSkipTracking<T>(
   return { result, softSkipCount: tracker.count };
 }
 
+/**
+ * Per-cycle ledger of HARD failures that must fail the cycle's verdict WITHOUT
+ * aborting sibling resources — a dead token (`getValidToken` returning null on
+ * a missing-credentials, failed-refresh, or in-lock vanished-connection path).
+ * Every resource leaf short-circuits `if (!tokenInfo) return 0` on a null
+ * token, so without this ledger a dead-token cycle reads as CLEAN: every
+ * resource "succeeds" with 0 rows, no failure is recorded, and
+ * `recordSyncSuccess` un-parks `error_reauth`, resets the failure buckets +
+ * `alertedAt`, and the hourly cohort hammers the dead refresh token forever.
+ * The orchestrator + the per-resource driver read this ledger to refuse the
+ * success stamp. Ported from Fitbit R2 / Google Health's `hardFailStorage`.
+ * Scoped by AsyncLocalStorage so concurrent per-user jobs never cross-pollinate.
+ */
+export interface HardFailTracker {
+  failures: string[];
+}
+export const hardFailStorage = new AsyncLocalStorage<HardFailTracker>();
+
+/**
+ * Ledger label for a dead-token failure (`getValidToken` returning null on a
+ * missing-credentials, failed-refresh, or in-lock vanished-connection path).
+ * Ported from Fitbit's `FITBIT_TOKEN_HARD_FAIL`.
+ */
+export const WHOOP_TOKEN_HARD_FAIL = "token";
+
+/**
+ * Record a hard failure on the ambient per-cycle ledger, if one is in scope.
+ * No-op outside a ledger scope (e.g. a direct REPL call). Used by
+ * `getValidToken`'s dead-token paths — anything that must fail the cycle's
+ * verdict without aborting sibling work. Ported from Fitbit's `noteHardFailure`.
+ */
+export function noteHardFailure(label: string): void {
+  const tracker = hardFailStorage.getStore();
+  if (tracker) tracker.failures.push(label);
+}
+
 /**
  * Single-source the per-resource collection-fetch error handling. A 403 on one
  * data class soft-skips it (warn + return 0) so sibling resources still sync;
@@ -122,7 +159,9 @@ export async function handleCollectionFetchError(
     return 0;
   }
   await recordWhoopSyncFailure(userId, err);
-  throw err;
+  // Marked so the orchestrator / cron catch (which records unmarked write-path
+  // throws for WH-4) does not record this fetch failure a SECOND time.
+  throw markSyncFailureRecorded(err);
 }
 
 /** Refresh the access token this many ms before `tokenExpiresAt`. */
@@ -137,8 +176,14 @@ const TOKEN_REFRESH_BUFFER_MS = 5 * 60 * 1000;
  * narrow overlap; the night's per-stage rows then never reach the DB and
  * every sleep surface keeps showing the parallel coarse source for that
  * night. Seven days re-fetches a handful of records per tick (the upserts
- * are idempotent) and closes the gap for every realistic lag. Workout/cycle
- * settle fast — a smaller overlap suffices and keeps the page count down.
+ * are idempotent) and closes the gap for every realistic lag. Workout AND
+ * cycle now ride the same 7-day overlap: a workout can reach the WHOOP cloud
+ * days after a late phone sync, and a cycle is re-scored through the day —
+ * both collections filter on the record's own time range, so a narrow overlap
+ * steps the cursor past a still-settling record and misses it. One record per
+ * day keeps the re-fetch to a single page. `WHOOP_DEFAULT_OVERLAP_MS` stays
+ * the narrow fallback `incrementalStart` uses when no resource passes an
+ * explicit overlap.
  */
 export const WHOOP_RECOVERY_SLEEP_OVERLAP_MS = 7 * 24 * 60 * 60 * 1000;
 export const WHOOP_DEFAULT_OVERLAP_MS = 60 * 60 * 1000; // 1 h
@@ -242,6 +287,11 @@ export async function getValidToken(
       message: "WHOOP credentials missing — token refresh skipped",
       errorCode: "credentials_missing",
     });
+    // A dead token means every resource "succeeds" with 0 rows — without a
+    // ledger entry the cycle reads as clean and `recordSyncSuccess` un-parks
+    // `error_reauth` while the hourly cohort hammers the dead refresh token.
+    // Fail the cycle's verdict so the park holds.
+    noteHardFailure(WHOOP_TOKEN_HARD_FAIL);
     return null;
   }
 
@@ -252,7 +302,14 @@ export async function getValidToken(
       const current = await tx.whoopConnection.findUnique({
         where: { userId },
       });
-      if (!current?.whoopUserId) return null;
+      if (!current?.whoopUserId) {
+        // The connection vanished on the re-read inside the advisory lock
+        // (disconnect/webhook race). Register on the ledger so the cycle does
+        // not stamp success over a connection that no longer exists — the same
+        // invariant as the refresh branch below.
+        noteHardFailure(WHOOP_TOKEN_HARD_FAIL);
+        return null;
+      }
 
       if (
         current.tokenExpiresAt.getTime() - TOKEN_REFRESH_BUFFER_MS >=
@@ -295,6 +352,9 @@ export async function getValidToken(
       `WHOOP token refresh failed for user ${userId}: ${err}`,
     );
     await recordWhoopSyncFailure(userId, err);
+    // The WH-1 kill shot: an all-zeros refresh-failure run must not stamp
+    // success, un-park `error_reauth`, and re-arm the alert. Fail the verdict.
+    noteHardFailure(WHOOP_TOKEN_HARD_FAIL);
     return null;
   }
 }
@@ -535,10 +595,18 @@ export async function syncWhoopResourceWithStatus(
   userId: string,
   run: () => Promise<number>,
 ): Promise<number> {
+  // Run under BOTH trackers: soft-skip (a 403 scope gate) and hard-fail (a dead
+  // token noted by `getValidToken`). This is the dominant path — the four
+  // hourly crons walk every connection through here — so without the hard-fail
+  // gate a dead-token tick would stamp success, un-park `error_reauth`, and the
+  // whole release would be inert on the path that runs most often.
+  const hardFailTracker: HardFailTracker = { failures: [] };
   const { result: imported, softSkipCount } =
-    await runWithWhoopSoftSkipTracking(run);
+    await runWithWhoopSoftSkipTracking(() =>
+      hardFailStorage.run(hardFailTracker, run),
+    );
   const softSkippedOnly = softSkipCount > 0 && imported === 0;
-  if (!softSkippedOnly) {
+  if (!softSkippedOnly && hardFailTracker.failures.length === 0) {
     await recordSyncSuccess(userId, "whoop");
   }
   return imported;
diff --git a/src/lib/whoop/sync-cycle.ts b/src/lib/whoop/sync-cycle.ts
index c4068ca6f..39c0488ad 100644
--- a/src/lib/whoop/sync-cycle.ts
+++ b/src/lib/whoop/sync-cycle.ts
@@ -13,6 +13,7 @@ import {
   markResourceSynced,
   resolveResourceCursor,
   upsertWhoopMeasurements,
+  WHOOP_RECOVERY_SLEEP_OVERLAP_MS,
   type WhoopMeasurementUpsert,
 } from "./sync-core";
 import { prisma } from "@/lib/db";
@@ -30,8 +31,16 @@ export async function syncUserCycle(
   });
   if (!connection) return 0;
 
+  // WHOOP re-scores a cycle THROUGH the day (day strain + energy accrue and
+  // settle after the fact) and the collection filters on the cycle's own time
+  // range, not on when it updated — so a narrow 1 h overlap could step the
+  // cursor past a cycle still being revised and miss the final value. Ride the
+  // same 7-day re-score overlap workout/recovery/sleep already use; one cycle
+  // per day means ~7 records re-fetched per tick (one page), and the
+  // `cycle:<id>:<fieldTag>` upsert keeps the overwrite idempotent.
   const start = incrementalStart(resolveResourceCursor(connection, "cycle"), {
     fullSync: opts.fullSync,
+    overlapMs: WHOOP_RECOVERY_SLEEP_OVERLAP_MS,
   });
 
   let records: Awaited<ReturnType<typeof fetchCycles>>;
diff --git a/src/lib/whoop/sync.ts b/src/lib/whoop/sync.ts
index a7e74bc0c..06855227c 100644
--- a/src/lib/whoop/sync.ts
+++ b/src/lib/whoop/sync.ts
@@ -6,13 +6,22 @@
  * the static leaf graph and the full per-user sequencing policy.
  */
 import { getEvent } from "@/lib/logging/context";
-import { isReauthRequired, recordSyncSuccess } from "@/lib/integrations/status";
+import {
+  isReauthRequired,
+  isSyncFailureRecorded,
+  recordSyncSuccess,
+} from "@/lib/integrations/status";
 import { syncUserRecovery } from "./sync-recovery";
 import { syncUserSleep } from "./sync-sleep";
 import { syncUserCycle } from "./sync-cycle";
 import { syncUserWorkout } from "./sync-workout";
 import { syncUserBody } from "./sync-body";
-import { runWithWhoopSoftSkipTracking } from "./sync-core";
+import {
+  hardFailStorage,
+  recordWhoopSyncFailure,
+  runWithWhoopSoftSkipTracking,
+  type HardFailTracker,
+} from "./sync-core";
 
 /**
  * Full per-user sync across every WHOOP resource. Webhook-driven syncs enqueue
@@ -20,17 +29,18 @@ import { runWithWhoopSoftSkipTracking } from "./sync-core";
  * manual `/api/whoop/sync` trigger.
  *
  * Parks immediately when the connection is at `error_reauth` (the user must
- * reconnect first) — returns 0, matching the Withings no-op contract.
+ * reconnect first) — returns `{ imported: 0, failed: true }`, matching the
+ * landed Fitbit verdict contract so the backfill caller can gate its marker.
  */
 export async function syncUserWhoop(
   userId: string,
   opts: { fullSync?: boolean } = {},
-): Promise<number> {
+): Promise<{ imported: number; failed: boolean }> {
   if (await isReauthRequired(userId, "whoop")) {
     getEvent()?.addWarning(
       `whoop sync skipped for ${userId}: parked at error_reauth`,
     );
-    return 0;
+    return { imported: 0, failed: true };
   }
 
   const resources = [
@@ -42,23 +52,41 @@ export async function syncUserWhoop(
   ];
 
   let anyFailed = false;
+  // Nest the hard-fail ledger inside the soft-skip tracker (manual nest, not a
+  // combined wrapper) so a dead token noted by `getValidToken` — or a marked
+  // fetch hard-fail — fails the verdict just like a thrown resource error.
+  const hardFailTracker: HardFailTracker = { failures: [] };
   const { result: total, softSkipCount } = await runWithWhoopSoftSkipTracking(
-    async () => {
-      let imported = 0;
-      for (const fn of resources) {
-        try {
-          imported += await fn(userId, opts);
-        } catch (err) {
-          anyFailed = true;
-          getEvent()?.addWarning(
-            `whoop ${fn.name} failed for ${userId}: ${err}`,
-          );
+    () =>
+      hardFailStorage.run(hardFailTracker, async () => {
+        let imported = 0;
+        for (const fn of resources) {
+          try {
+            imported += await fn(userId, opts);
+          } catch (err) {
+            anyFailed = true;
+            // WH-4: a write-path throw (`MeasurementReconciliationError` out of
+            // `upsertWhoopMeasurements`) reaches no ledger otherwise — a
+            // stale-green pill during a persistent write failure. Fetch
+            // hard-fails already recorded + marked in `handleCollectionFetchError`,
+            // so record only the UNMARKED escapes here (no double-record).
+            if (!isSyncFailureRecorded(err)) {
+              await recordWhoopSyncFailure(userId, err);
+            }
+            getEvent()?.addWarning(
+              `whoop ${fn.name} failed for ${userId}: ${err}`,
+            );
+          }
         }
-      }
-      return imported;
-    },
+        return imported;
+      }),
   );
 
+  // A dead token / vanished connection notes the hard-fail ledger without
+  // throwing (each leaf short-circuits `if (!tokenInfo) return 0`); fold that
+  // into the verdict so an all-zeros dead-token cycle does not stamp success.
+  anyFailed = anyFailed || hardFailTracker.failures.length > 0;
+
   // A genuine grant-revoke 403s EVERY collection: each resource soft-skips
   // (returns 0, records no failure), so `anyFailed` stays false and `total` is
   // 0 — yet the connection is dead until the token-refresh path next catches
@@ -71,5 +99,5 @@ export async function syncUserWhoop(
   if (!anyFailed && !allSoftSkipped) {
     await recordSyncSuccess(userId, "whoop");
   }
-  return total;
+  return { imported: total, failed: anyFailed || allSoftSkipped };
 }
diff --git a/src/lib/withings/__tests__/sync-activity.test.ts b/src/lib/withings/__tests__/sync-activity.test.ts
index c34b0d512..0f9c2a80d 100644
--- a/src/lib/withings/__tests__/sync-activity.test.ts
+++ b/src/lib/withings/__tests__/sync-activity.test.ts
@@ -373,6 +373,31 @@ describe("syncUserActivity — field mapping + idempotency", () => {
     expect(recordSyncSuccess).toHaveBeenCalledWith("user-1", "withings");
   });
 
+  it("W-2 — records a transient failure and refuses the success stamp when the batch write throws", async () => {
+    // A swallowed batch-write used to fall through to recordSyncSuccess: green
+    // pill over lost data, and a PERSISTENT write bug green forever. The write
+    // failure now records a transient failure and the success stamp is skipped.
+    installFetchMock([
+      { date: "2026-05-12", steps: 8420, distance: 6720, calories: 412 },
+    ]);
+    vi.mocked(prisma.measurement.findMany).mockResolvedValue([] as never);
+    vi.mocked(prisma.measurement.createMany).mockRejectedValue(
+      new Error("db write blew up"),
+    );
+
+    // No rethrow — sibling chunks + the rollup fold still run (matches Google).
+    await expect(syncUserActivity("user-1")).resolves.toBeGreaterThanOrEqual(0);
+
+    expect(recordSyncSuccess).not.toHaveBeenCalled();
+    expect(recordSyncFailure).toHaveBeenCalledWith(
+      expect.objectContaining({
+        integration: "withings",
+        kind: "transient",
+        message: expect.stringContaining("activity batch write failed"),
+      }),
+    );
+  });
+
   it("tags every row with the canonical externalId so future replays dedup", async () => {
     installFetchMock([{ date: "2026-05-12", steps: 8420 }]);
     vi.mocked(prisma.measurement.findMany).mockResolvedValue([] as never);
diff --git a/src/lib/withings/__tests__/sync-sleep.test.ts b/src/lib/withings/__tests__/sync-sleep.test.ts
index 565455c02..98fcff22d 100644
--- a/src/lib/withings/__tests__/sync-sleep.test.ts
+++ b/src/lib/withings/__tests__/sync-sleep.test.ts
@@ -473,6 +473,32 @@ describe("syncUserSleep — segment writes + idempotency", () => {
     expect(recordSyncSuccess).toHaveBeenCalledWith("user-1", "withings");
   });
 
+  it("W-3 — records a transient failure and rethrows when a sleep write throws", async () => {
+    // A reconcile throw out of the stage transaction used to propagate past the
+    // success stamp and get swallowed by both callers: neither success NOR
+    // failure recorded, `lastAttemptAt` quietly stale. Now the source records a
+    // transient failure and rethrows (callers keep their warn-and-continue).
+    installFetchMock([
+      { startdate: 1715000000, enddate: 1715003600, state: 2, id: 1 },
+    ]);
+    reconcileMock.mockReset().mockResolvedValueOnce({
+      status: "failed",
+      reason: "db_error",
+      error: new Error("reconcile boom"),
+    });
+
+    await expect(syncUserSleep("user-1")).rejects.toThrow();
+
+    expect(recordSyncFailure).toHaveBeenCalledWith(
+      expect.objectContaining({
+        integration: "withings",
+        kind: "transient",
+        message: expect.stringContaining("sleep write failed"),
+      }),
+    );
+    expect(recordSyncSuccess).not.toHaveBeenCalled();
+  });
+
   it("upserts nightly vitals with stable per-vital externalIds (v1.18.10 P0)", async () => {
     const nightEnd = Math.floor(Date.UTC(2026, 4, 13, 6) / 1000);
     installSegmentThenSummaryFetch(
diff --git a/src/lib/withings/sync-activity.ts b/src/lib/withings/sync-activity.ts
index ca21ad6ca..05431f7ef 100644
--- a/src/lib/withings/sync-activity.ts
+++ b/src/lib/withings/sync-activity.ts
@@ -311,6 +311,11 @@ export async function syncUserActivity(
   }
 
   let imported = 0;
+  // W-2 — a swallowed batch-write must not read as a clean sync. The catch
+  // below sets this so the tail stamps success ONLY when the write landed; a
+  // persistent write bug then accrues strikes instead of being reset by its
+  // own success stamp every tick.
+  let writeFailed = false;
   // v1.4.39.1 — track every (type, measuredAt) we touched so the
   // persistent rollup tier can be re-folded at the end of the sync.
   // See sync.ts header for the full rationale; the chart's
@@ -446,9 +451,24 @@ export async function syncUserActivity(
         );
       }
     } catch (err) {
+      // Data is lost for this tick and the pill would otherwise read green. Keep
+      // the no-rethrow (sibling day-chunks + the rollup fold still run) but
+      // record a transient failure and refuse the success stamp below.
+      // `transient` because the next hourly tick re-walks the fixed 30-day
+      // window, so a transient DB error self-heals while a persistent one now
+      // surfaces on the status card instead of resetting itself.
+      writeFailed = true;
       getEvent()?.addWarning(
         `Failed to batch-upsert ${planned.length} activity rows for ${userId}: ${err}`,
       );
+      await recordSyncFailure({
+        userId,
+        integration: "withings",
+        kind: "transient",
+        message: `activity batch write failed: ${
+          err instanceof Error ? err.message : String(err)
+        }`,
+      });
     }
   }
 
@@ -477,6 +497,10 @@ export async function syncUserActivity(
     );
   }
 
-  await recordSyncSuccess(userId, "withings");
+  // W-2 — only a clean write stamps success. A swallowed batch-write left the
+  // ledger honest via the transient failure recorded above.
+  if (!writeFailed) {
+    await recordSyncSuccess(userId, "withings");
+  }
   return imported;
 }
diff --git a/src/lib/withings/sync-sleep.ts b/src/lib/withings/sync-sleep.ts
index f878d39a1..37ba27262 100644
--- a/src/lib/withings/sync-sleep.ts
+++ b/src/lib/withings/sync-sleep.ts
@@ -412,51 +412,74 @@ export async function syncUserSleep(
   // and are excluded (their `no-id` prefix would span every id-less night in
   // history, not just this fetch).
   const freshBySession = new Map<number, string[]>();
-  await prisma.$transaction(
-    async (tx) => {
-      for (const segment of segments) {
-        const stage = mapWithingsSleepState(segment.state);
-        if (!stage) continue;
 
-        const measuredAt = new Date(segment.enddate * 1000);
-        const durationSec = Math.max(0, segment.enddate - segment.startdate);
-        const minutes = Math.round(durationSec / 60);
-        const externalId = `withings:sleep:${userId}:${segment.id ?? "no-id"}:${segment.startdate}`;
-        if (typeof segment.id === "number") {
-          const fresh = freshBySession.get(segment.id) ?? [];
-          fresh.push(externalId);
-          freshBySession.set(segment.id, fresh);
-        }
+  // W-3 — a reconcile throw out of either sleep transaction propagated past the
+  // success stamp and both callers (cron + webhook) swallowed it: neither
+  // success NOR failure was recorded, so `lastAttemptAt` sat quietly stale
+  // during a persistent write failure. Record a transient failure at the source
+  // AND rethrow — preserving the callers' existing warn-and-continue cohort
+  // semantics — so the write failure surfaces on the status card without
+  // touching either caller. The fetch-side `WithingsApiError` path already
+  // records + rethrows above, so it never reaches these blocks.
+  const recordSleepWriteFailure = async (err: unknown): Promise<never> => {
+    await recordSyncFailure({
+      userId,
+      integration: "withings",
+      kind: "transient",
+      message: `sleep write failed: ${
+        err instanceof Error ? err.message : String(err)
+      }`,
+    });
+    throw err;
+  };
 
-        const verdict = await reconcileExternalMeasurement(
-          tx,
-          {
-            userId,
-            type: SLEEP_TYPE,
-            value: minutes,
-            unit: getUnitForType(SLEEP_TYPE),
-            measuredAt,
-            source: "WITHINGS",
-            sleepStage: stage,
-            externalId,
-          },
-          { exactExternalMatch: "update" },
-        );
-        if (verdict.status === "failed") {
-          throw new MeasurementReconciliationError(verdict);
+  await prisma
+    .$transaction(
+      async (tx) => {
+        for (const segment of segments) {
+          const stage = mapWithingsSleepState(segment.state);
+          if (!stage) continue;
+
+          const measuredAt = new Date(segment.enddate * 1000);
+          const durationSec = Math.max(0, segment.enddate - segment.startdate);
+          const minutes = Math.round(durationSec / 60);
+          const externalId = `withings:sleep:${userId}:${segment.id ?? "no-id"}:${segment.startdate}`;
+          if (typeof segment.id === "number") {
+            const fresh = freshBySession.get(segment.id) ?? [];
+            fresh.push(externalId);
+            freshBySession.set(segment.id, fresh);
+          }
+
+          const verdict = await reconcileExternalMeasurement(
+            tx,
+            {
+              userId,
+              type: SLEEP_TYPE,
+              value: minutes,
+              unit: getUnitForType(SLEEP_TYPE),
+              measuredAt,
+              source: "WITHINGS",
+              sleepStage: stage,
+              externalId,
+            },
+            { exactExternalMatch: "update" },
+          );
+          if (verdict.status === "failed") {
+            throw new MeasurementReconciliationError(verdict);
+          }
+          for (const dirty of verdict.dirtyIdentities ?? []) {
+            touched.push(dirty);
+          }
+          if (verdict.status === "inserted") {
+            insertedSleepMeasuredAts.push(measuredAt);
+          }
+          touched.push({ type: SLEEP_TYPE, measuredAt });
+          imported++;
         }
-        for (const dirty of verdict.dirtyIdentities ?? []) {
-          touched.push(dirty);
-        }
-        if (verdict.status === "inserted") {
-          insertedSleepMeasuredAts.push(measuredAt);
-        }
-        touched.push({ type: SLEEP_TYPE, measuredAt });
-        imported++;
-      }
-    },
-    { timeout: 60_000 },
-  );
+      },
+      { timeout: 60_000 },
+    )
+    .catch(recordSleepWriteFailure);
 
   // Session-scoped sweep (mirrors Google Health's replace-by-window): for each
   // session this fetch re-produced, soft-delete any live WITHINGS
@@ -489,38 +512,40 @@ export async function syncUserSleep(
     );
   }
 
-  await prisma.$transaction(
-    async (tx) => {
-      for (const summary of summaries) {
-        const measuredAt = new Date(summary.enddate * 1000);
-        const sessionId = summary.id ?? "no-id";
-        for (const vital of mapWithingsSleepSummary(summary.data)) {
-          const verdict = await reconcileExternalMeasurement(
-            tx,
-            {
-              userId,
-              type: vital.type,
-              value: vital.value,
-              unit: getUnitForType(vital.type),
-              measuredAt,
-              source: "WITHINGS",
-              externalId: `withings:sleep:${userId}:${sessionId}:${vital.fieldTag}`,
-            },
-            { exactExternalMatch: "update" },
-          );
-          if (verdict.status === "failed") {
-            throw new MeasurementReconciliationError(verdict);
+  await prisma
+    .$transaction(
+      async (tx) => {
+        for (const summary of summaries) {
+          const measuredAt = new Date(summary.enddate * 1000);
+          const sessionId = summary.id ?? "no-id";
+          for (const vital of mapWithingsSleepSummary(summary.data)) {
+            const verdict = await reconcileExternalMeasurement(
+              tx,
+              {
+                userId,
+                type: vital.type,
+                value: vital.value,
+                unit: getUnitForType(vital.type),
+                measuredAt,
+                source: "WITHINGS",
+                externalId: `withings:sleep:${userId}:${sessionId}:${vital.fieldTag}`,
+              },
+              { exactExternalMatch: "update" },
+            );
+            if (verdict.status === "failed") {
+              throw new MeasurementReconciliationError(verdict);
+            }
+            for (const dirty of verdict.dirtyIdentities ?? []) {
+              touched.push(dirty);
+            }
+            touched.push({ type: vital.type, measuredAt });
+            imported++;
           }
-          for (const dirty of verdict.dirtyIdentities ?? []) {
-            touched.push(dirty);
-          }
-          touched.push({ type: vital.type, measuredAt });
-          imported++;
         }
-      }
-    },
-    { timeout: 60_000 },
-  );
+      },
+      { timeout: 60_000 },
+    )
+    .catch(recordSleepWriteFailure);
 
   // v1.4.39.1 — refresh the persistent rollup table for every distinct
   // (type, day) the sync touched. Sleep segments collapse heavily —