diff --git a/src/lib/integrations/__tests__/http-status-classifier.test.ts b/src/lib/integrations/__tests__/http-status-classifier.test.ts
new file mode 100644
index 000000000..6754fe085
--- /dev/null
+++ b/src/lib/integrations/__tests__/http-status-classifier.test.ts
@@ -0,0 +1,204 @@
+import { describe, expect, it } from "vitest";
+import {
+  classifyHttpStatus,
+  classifyIntegrationError,
+  IntegrationApiError,
+  isOAuthInvalidGrant,
+} from "../http-status-classifier";
+import { toFailureKind } from "../status";
+
+describe("classifyHttpStatus", () => {
+  it("classifies 2xx as success", () => {
+    for (const status of [200, 201, 204, 299]) {
+      const v = classifyHttpStatus(status);
+      expect(v.classification).toBe("success");
+      expect(v.httpStatus).toBe(status);
+      expect(v.reason).toBe("ok");
+    }
+  });
+
+  it("classifies 429 as transient (rate-limit)", () => {
+    const v = classifyHttpStatus(429);
+    expect(v.classification).toBe("transient");
+    expect(v.reason).toBe("http_429");
+  });
+
+  it("classifies 401 and 403 as reauth_required", () => {
+    expect(classifyHttpStatus(401).classification).toBe("reauth_required");
+    expect(classifyHttpStatus(403).classification).toBe("reauth_required");
+    expect(classifyHttpStatus(401).reason).toBe("http_401");
+  });
+
+  it("classifies other 4xx as persistent", () => {
+    for (const status of [400, 404, 422]) {
+      const v = classifyHttpStatus(status);
+      expect(v.classification).toBe("persistent");
+      expect(v.reason).toBe(`http_${status}`);
+    }
+  });
+
+  it("classifies 5xx as transient", () => {
+    for (const status of [500, 502, 503]) {
+      expect(classifyHttpStatus(status).classification).toBe("transient");
+    }
+  });
+
+  it("classifies an unknown / 3xx status as transient with _unknown reason", () => {
+    const v = classifyHttpStatus(302);
+    expect(v.classification).toBe("transient");
+    expect(v.reason).toBe("http_302_unknown");
+  });
+});
+
+describe("IntegrationApiError", () => {
+  it("carries the vendor label in the message prefix and on the field", () => {
+    const err = new IntegrationApiError({
+      vendor: "Acme",
+      verb: "fetch",
+      classification: "reauth_required",
+      httpStatus: 401,
+      reason: "http_401",
+    });
+    expect(err.message).toBe("Acme fetch error: 401");
+    expect(err.vendor).toBe("Acme");
+    expect(err.classification).toBe("reauth_required");
+  });
+
+  it("appends the upstream error segment and caps at 1024 chars", () => {
+    const err = new IntegrationApiError({
+      vendor: "Acme",
+      verb: "token",
+      classification: "persistent",
+      httpStatus: 400,
+      reason: "http_400",
+      upstreamError: "invalid_grant",
+    });
+    expect(err.message).toBe("Acme token error: 400 - invalid_grant");
+
+    const huge = new IntegrationApiError({
+      vendor: "Acme",
+      verb: "fetch",
+      classification: "transient",
+      httpStatus: 500,
+      reason: "http_500",
+      upstreamError: "x".repeat(5000),
+    });
+    expect(huge.message.length).toBe(1024);
+  });
+});
+
+describe("isOAuthInvalidGrant", () => {
+  it("lifts a 400 invalid_grant from the upstreamError field", () => {
+    const err = new IntegrationApiError({
+      vendor: "Acme",
+      verb: "token",
+      classification: "persistent",
+      httpStatus: 400,
+      reason: "http_400",
+      upstreamError: "invalid_grant",
+    });
+    expect(isOAuthInvalidGrant(err, "Acme")).toBe(true);
+  });
+
+  it("does not lift a non-400 or a non-invalid_grant body", () => {
+    const wrongStatus = new IntegrationApiError({
+      vendor: "Acme",
+      verb: "token",
+      classification: "reauth_required",
+      httpStatus: 401,
+      reason: "http_401",
+      upstreamError: "invalid_grant",
+    });
+    expect(isOAuthInvalidGrant(wrongStatus, "Acme")).toBe(false);
+
+    const wrongBody = new IntegrationApiError({
+      vendor: "Acme",
+      verb: "token",
+      classification: "persistent",
+      httpStatus: 400,
+      reason: "http_400",
+      upstreamError: "invalid_client",
+    });
+    expect(isOAuthInvalidGrant(wrongBody, "Acme")).toBe(false);
+  });
+
+  it("falls back to the vendor-scoped message shape across a lost prototype", () => {
+    expect(
+      isOAuthInvalidGrant(
+        new Error("Acme token error: 400 - invalid_grant"),
+        "Acme",
+      ),
+    ).toBe(true);
+    // Wrong vendor label in the message → no match.
+    expect(
+      isOAuthInvalidGrant(
+        new Error("Other token error: 400 - invalid_grant"),
+        "Acme",
+      ),
+    ).toBe(false);
+  });
+
+  it("returns false for a plain non-API error", () => {
+    expect(isOAuthInvalidGrant(new Error("network down"), "Acme")).toBe(false);
+    expect(isOAuthInvalidGrant("boom", "Acme")).toBe(false);
+  });
+});
+
+describe("classifyIntegrationError", () => {
+  it("reads the classification off an IntegrationApiError", () => {
+    const err = new IntegrationApiError({
+      vendor: "Acme",
+      verb: "fetch",
+      classification: "persistent",
+      httpStatus: 404,
+      reason: "http_404",
+    });
+    expect(classifyIntegrationError(err, "Acme")).toBe("persistent");
+  });
+
+  it("parses the status out of a legacy vendor-scoped message", () => {
+    expect(
+      classifyIntegrationError(new Error("Acme fetch error: 503"), "Acme"),
+    ).toBe("transient");
+    expect(
+      classifyIntegrationError(new Error("Acme fetch error: 401"), "Acme"),
+    ).toBe("reauth_required");
+  });
+
+  it("defaults to transient for an unparseable error", () => {
+    expect(classifyIntegrationError(new Error("network down"), "Acme")).toBe(
+      "transient",
+    );
+    expect(classifyIntegrationError("boom", "Acme")).toBe("transient");
+  });
+});
+
+describe("toFailureKind", () => {
+  it("maps reauth_required and persistent through unchanged", () => {
+    expect(toFailureKind("reauth_required")).toBe("reauth_required");
+    expect(toFailureKind("persistent")).toBe("persistent");
+  });
+
+  it("collapses success and transient onto transient", () => {
+    expect(toFailureKind("transient")).toBe("transient");
+    expect(toFailureKind("success")).toBe("transient");
+  });
+
+  it("maps the boundary HTTP codes end-to-end", () => {
+    expect(toFailureKind(classifyHttpStatus(401).classification)).toBe(
+      "reauth_required",
+    );
+    expect(toFailureKind(classifyHttpStatus(403).classification)).toBe(
+      "reauth_required",
+    );
+    expect(toFailureKind(classifyHttpStatus(404).classification)).toBe(
+      "persistent",
+    );
+    expect(toFailureKind(classifyHttpStatus(500).classification)).toBe(
+      "transient",
+    );
+    expect(toFailureKind(classifyHttpStatus(429).classification)).toBe(
+      "transient",
+    );
+  });
+});
diff --git a/src/lib/integrations/http-status-classifier.ts b/src/lib/integrations/http-status-classifier.ts
new file mode 100644
index 000000000..fe10349c8
--- /dev/null
+++ b/src/lib/integrations/http-status-classifier.ts
@@ -0,0 +1,182 @@
+/**
+ * v1.17.0 — shared HTTP-status response classifier for OAuth integrations.
+ *
+ * Polar, Oura, WHOOP and Fitbit all signal failure through the HTTP status
+ * code itself (no `status` field embedded in a 200 body), so their off-response
+ * classifiers were byte-identical copies of one another. This module lifts the
+ * shared core; each vendor module re-exports it under its existing names so
+ * call sites keep their current types.
+ *
+ * Classification buckets:
+ *
+ *   - `success`         → HTTP 2xx (incl. 204 No Content).
+ *   - `transient`       → retryable: 429 (rate-limited), 5xx upstream outages,
+ *                         3xx CDN/redirect glitches, and an unknown status.
+ *   - `reauth_required` → 401 / 403 — the access token is rejected or the grant
+ *                         was revoked; the user must reconnect.
+ *   - `persistent`      → any other 4xx — a malformed request / contract
+ *                         mismatch that a retry won't fix.
+ *
+ * The classifier is conservative: anything it doesn't recognise defaults to
+ * `transient` so a single unknown response doesn't hard-disable the
+ * integration. The 3-strike admin-alert ladder in `recordSyncFailure` already
+ * catches the "keeps happening" case for recurring transients.
+ */
+
+/** Outcome buckets shared across the HTTP-status-driven integrations. */
+export type IntegrationClassification =
+  | "success"
+  | "transient"
+  | "reauth_required"
+  | "persistent";
+
+export interface ClassifiedHttpResponse {
+  classification: IntegrationClassification;
+  /** The HTTP status code that drove the verdict (undefined if none seen). */
+  httpStatus: number | undefined;
+  /** Short human-readable label for logs / audit details. */
+  reason: string;
+}
+
+/**
+ * Classify a single integration API response by its HTTP status code.
+ *
+ * @param httpStatus  The HTTP status from fetch.
+ */
+export function classifyHttpStatus(httpStatus: number): ClassifiedHttpResponse {
+  if (httpStatus >= 200 && httpStatus < 300) {
+    return { classification: "success", httpStatus, reason: "ok" };
+  }
+  // 429 is rate-limit — honour the vendor's backoff header at the call site,
+  // but the verdict is a plain transient so the next sync retries.
+  if (httpStatus === 429) {
+    return { classification: "transient", httpStatus, reason: "http_429" };
+  }
+  // 401/403 — the bearer token is rejected or the grant revoked. The user has
+  // to reconnect; do not retry silently.
+  if (httpStatus === 401 || httpStatus === 403) {
+    return {
+      classification: "reauth_required",
+      httpStatus,
+      reason: `http_${httpStatus}`,
+    };
+  }
+  // Any other 4xx is a malformed request / contract mismatch — persistent.
+  if (httpStatus >= 400 && httpStatus < 500) {
+    return {
+      classification: "persistent",
+      httpStatus,
+      reason: `http_${httpStatus}`,
+    };
+  }
+  // 5xx upstream outage — retryable.
+  if (httpStatus >= 500 && httpStatus < 600) {
+    return {
+      classification: "transient",
+      httpStatus,
+      reason: `http_${httpStatus}`,
+    };
+  }
+  // 3xx (a CDN / redirect glitch — safeFetch uses redirect:"manual", so a
+  // surfaced 3xx is unexpected) and everything else defaults to transient.
+  return {
+    classification: "transient",
+    httpStatus,
+    reason: `http_${httpStatus}_unknown`,
+  };
+}
+
+/**
+ * Typed Error base carrying the classification verdict so downstream
+ * `try/catch` blocks can branch without re-parsing the message. Each vendor
+ * subclass sets `vendor` (the wire label used in the message prefix) and its
+ * own `name`; the message shape (`<Vendor> <verb> error: <status> - <err>`,
+ * capped at 1024 chars) is identical across vendors.
+ */
+export class IntegrationApiError extends Error {
+  readonly vendor: string;
+  readonly classification: IntegrationClassification;
+  readonly httpStatus: number | undefined;
+  readonly reason: string;
+  readonly verb: string;
+  /**
+   * The OAuth `error` code from a token-endpoint failure body (e.g.
+   * `invalid_grant` when a refresh token is revoked). Undefined for the
+   * collection endpoints, which signal failure through the status code alone.
+   */
+  readonly upstreamError: string | undefined;
+
+  constructor(opts: {
+    vendor: string;
+    verb: string;
+    classification: IntegrationClassification;
+    httpStatus: number | undefined;
+    reason: string;
+    upstreamError?: string;
+  }) {
+    const statusLabel =
+      typeof opts.httpStatus === "number" ? opts.httpStatus : "?";
+    const errSegment = opts.upstreamError ? ` - ${opts.upstreamError}` : "";
+    // Cap the message at 1024 chars so a misbehaving upstream returning a
+    // multi-MB error body can't bloat an AuditLog row downstream.
+    const raw = `${opts.vendor} ${opts.verb} error: ${statusLabel}${errSegment}`;
+    super(raw.slice(0, 1024));
+    this.name = "IntegrationApiError";
+    this.vendor = opts.vendor;
+    this.verb = opts.verb;
+    this.classification = opts.classification;
+    this.httpStatus = opts.httpStatus;
+    this.reason = opts.reason;
+    this.upstreamError = opts.upstreamError;
+  }
+}
+
+/**
+ * True when a caught error is an OAuth `invalid_grant` on a 400 from the token
+ * endpoint — the canonical signal that the stored refresh token was revoked
+ * (the user disconnected the app, or the upstream expired the grant). A plain
+ * `classifyHttpStatus(400)` buckets this as `persistent`, which never prompts a
+ * reconnect; lifting it to `reauth_required` makes the connection surface the
+ * reauth prompt. Scoped tightly to a 400 carrying `invalid_grant` so other
+ * 400s (a malformed request, a bad client_secret → `invalid_client`) stay
+ * persistent.
+ *
+ * Robust to a lost prototype across a pg-boss retry: it reads the dedicated
+ * `upstreamError` field when present, else falls back to the
+ * `"<Vendor> <verb> error: 400 - invalid_grant"` message segment. The `vendor`
+ * label scopes the message-shape fallback to the calling integration.
+ */
+export function isOAuthInvalidGrant(err: unknown, vendor: string): boolean {
+  if (err instanceof IntegrationApiError) {
+    if (err.httpStatus !== 400) return false;
+    if (err.upstreamError === "invalid_grant") return true;
+    return /\binvalid_grant\b/.test(err.message);
+  }
+  const msg = err instanceof Error ? err.message : String(err);
+  const re = new RegExp(
+    `${vendor}\\s+\\w+\\s+error:\\s*400\\b[\\s\\S]*\\binvalid_grant\\b`,
+  );
+  return re.test(msg);
+}
+
+/**
+ * Read the classification from any caught `IntegrationApiError`, falling back
+ * to parsing the HTTP status out of the legacy `"<Vendor> <verb> error:
+ * <status>"` message shape for callers that lose the original prototype across
+ * a pg-boss retry. A non-`IntegrationApiError` with no parseable status
+ * defaults to `transient` so a plain `Error` retries rather than permanently
+ * disabling the integration.
+ */
+export function classifyIntegrationError(
+  err: unknown,
+  vendor: string,
+): IntegrationClassification {
+  if (err instanceof IntegrationApiError) return err.classification;
+  const msg = err instanceof Error ? err.message : String(err);
+  const re = new RegExp(`${vendor}\\s+\\w+\\s+error:\\s*(\\d+)`);
+  const m = re.exec(msg);
+  if (!m) return "transient";
+  const status = Number.parseInt(m[1]!, 10);
+  if (!Number.isFinite(status)) return "transient";
+  return classifyHttpStatus(status).classification;
+}
diff --git a/src/lib/integrations/status.ts b/src/lib/integrations/status.ts
index ef0fd09c9..41c3fda75 100644
--- a/src/lib/integrations/status.ts
+++ b/src/lib/integrations/status.ts
@@ -38,6 +38,7 @@ import { encrypt, decrypt } from "@/lib/crypto";
 import { auditLog } from "@/lib/auth/audit";
 import { getEvent } from "@/lib/logging/context";
 import { dispatchNotification } from "@/lib/notifications/dispatcher";
+import type { IntegrationClassification } from "@/lib/integrations/http-status-classifier";
 
 export type IntegrationKey =
   | "withings"
@@ -74,6 +75,23 @@ export type IntegrationKey =
  */
 export type FailureKind = "transient" | "reauth_required" | "persistent";
 
+/**
+ * Map a shared `IntegrationClassification` onto the ledger `FailureKind`.
+ *
+ * `success` never reaches a failure path, so it collapses into `transient`
+ * alongside the genuinely-retryable verdicts; `reauth_required` and
+ * `persistent` pass through unchanged. Lifted out of the per-vendor
+ * `classifyXFailure` adapters (Polar / Oura / Nightscout), which each carried a
+ * byte-identical copy of this mapping.
+ */
+export function toFailureKind(
+  classification: IntegrationClassification,
+): FailureKind {
+  if (classification === "reauth_required") return "reauth_required";
+  if (classification === "persistent") return "persistent";
+  return "transient";
+}
+
 /**
  * Recognised IntegrationStatus states.
  *
diff --git a/src/lib/nightscout/__tests__/sync.test.ts b/src/lib/nightscout/__tests__/sync.test.ts
index 764c0fb71..cfd6fefc8 100644
--- a/src/lib/nightscout/__tests__/sync.test.ts
+++ b/src/lib/nightscout/__tests__/sync.test.ts
@@ -26,7 +26,8 @@ vi.mock("@/lib/db", () => ({
   prisma: { measurement: { upsert: upsertMock } },
 }));
 
-vi.mock("@/lib/integrations/status", () => ({
+vi.mock("@/lib/integrations/status", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("@/lib/integrations/status")>()),
   recordSyncSuccess: recordSuccessMock,
   recordSyncFailure: recordFailureMock,
 }));
diff --git a/src/lib/nightscout/sync.ts b/src/lib/nightscout/sync.ts
index 06e5e39c9..185b2e417 100644
--- a/src/lib/nightscout/sync.ts
+++ b/src/lib/nightscout/sync.ts
@@ -25,8 +25,10 @@ import { getEvent } from "@/lib/logging/context";
 import {
   recordSyncFailure,
   recordSyncSuccess,
+  toFailureKind,
   type FailureKind,
 } from "@/lib/integrations/status";
+import type { IntegrationClassification } from "@/lib/integrations/http-status-classifier";
 import {
   collapseToTypeDayKeys,
   recomputeBucketsForMeasurement,
@@ -72,14 +74,18 @@ export function redactNightscoutSecret(message: string): string {
 
 /** Map a Nightscout HTTP status / network error onto the shared ledger kind. */
 export function classifyNightscoutFailure(err: unknown): FailureKind {
+  let classification: IntegrationClassification = "transient";
   if (err instanceof NightscoutApiError && err.status != null) {
     // Wrong / missing token, or a token whose role can't read SGV.
-    if (err.status === 401 || err.status === 403) return "reauth_required";
-    // 4xx other than auth = a contract / config problem worth surfacing.
-    if (err.status >= 400 && err.status < 500) return "persistent";
+    if (err.status === 401 || err.status === 403) {
+      classification = "reauth_required";
+    } else if (err.status >= 400 && err.status < 500) {
+      // 4xx other than auth = a contract / config problem worth surfacing.
+      classification = "persistent";
+    }
   }
-  // 5xx, timeout, DNS, connection refused — retry on the next tick.
-  return "transient";
+  // 5xx, timeout, DNS, connection refused stay `transient` — retry next tick.
+  return toFailureKind(classification);
 }
 
 /**
diff --git a/src/lib/oura/__tests__/sync.test.ts b/src/lib/oura/__tests__/sync.test.ts
index e242401d5..2d0fc91eb 100644
--- a/src/lib/oura/__tests__/sync.test.ts
+++ b/src/lib/oura/__tests__/sync.test.ts
@@ -37,7 +37,8 @@ vi.mock("@/lib/db", () => ({
   prisma: { measurement: { upsert: upsertMock } },
 }));
 
-vi.mock("@/lib/integrations/status", () => ({
+vi.mock("@/lib/integrations/status", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("@/lib/integrations/status")>()),
   recordSyncSuccess: recordSuccessMock,
   recordSyncFailure: recordFailureMock,
 }));
diff --git a/src/lib/oura/response-classifier.ts b/src/lib/oura/response-classifier.ts
index 0f3e39ea8..0477cee1d 100644
--- a/src/lib/oura/response-classifier.ts
+++ b/src/lib/oura/response-classifier.ts
@@ -1,6 +1,8 @@
 /**
  * v1.17.0 (F4) — off-response classifier for Oura Cloud API v2 replies.
- * Mirrors the WHOOP / Polar classifiers: HTTP-status-driven.
+ * HTTP-status-driven; the shared core lives in
+ * `src/lib/integrations/http-status-classifier.ts` and is re-exported here
+ * under the Oura-specific names callers already use.
  *
  *   - `success`         → HTTP 2xx
  *   - `transient`       → 429 (rate-limited), 5xx, 3xx, unknown.
@@ -8,62 +10,26 @@
  *   - `persistent`      → any other 4xx — malformed request / contract drift.
  */
 
-export type OuraClassification =
-  | "success"
-  | "transient"
-  | "reauth_required"
-  | "persistent";
+import {
+  classifyHttpStatus,
+  classifyIntegrationError,
+  IntegrationApiError,
+  isOAuthInvalidGrant,
+  type ClassifiedHttpResponse,
+  type IntegrationClassification,
+} from "@/lib/integrations/http-status-classifier";
 
-export interface ClassifiedOuraResponse {
-  classification: OuraClassification;
-  httpStatus: number | undefined;
-  reason: string;
-}
+export type OuraClassification = IntegrationClassification;
+
+export type ClassifiedOuraResponse = ClassifiedHttpResponse;
 
 export function classifyOuraResponse(
   httpStatus: number,
 ): ClassifiedOuraResponse {
-  if (httpStatus >= 200 && httpStatus < 300) {
-    return { classification: "success", httpStatus, reason: "ok" };
-  }
-  if (httpStatus === 429) {
-    return { classification: "transient", httpStatus, reason: "http_429" };
-  }
-  if (httpStatus === 401 || httpStatus === 403) {
-    return {
-      classification: "reauth_required",
-      httpStatus,
-      reason: `http_${httpStatus}`,
-    };
-  }
-  if (httpStatus >= 400 && httpStatus < 500) {
-    return {
-      classification: "persistent",
-      httpStatus,
-      reason: `http_${httpStatus}`,
-    };
-  }
-  if (httpStatus >= 500 && httpStatus < 600) {
-    return {
-      classification: "transient",
-      httpStatus,
-      reason: `http_${httpStatus}`,
-    };
-  }
-  return {
-    classification: "transient",
-    httpStatus,
-    reason: `http_${httpStatus}_unknown`,
-  };
+  return classifyHttpStatus(httpStatus);
 }
 
-export class OuraApiError extends Error {
-  readonly classification: OuraClassification;
-  readonly httpStatus: number | undefined;
-  readonly reason: string;
-  readonly verb: string;
-  readonly upstreamError: string | undefined;
-
+export class OuraApiError extends IntegrationApiError {
   constructor(opts: {
     verb: string;
     classification: OuraClassification;
@@ -71,17 +37,8 @@ export class OuraApiError extends Error {
     reason: string;
     upstreamError?: string;
   }) {
-    const statusLabel =
-      typeof opts.httpStatus === "number" ? opts.httpStatus : "?";
-    const errSegment = opts.upstreamError ? ` - ${opts.upstreamError}` : "";
-    const raw = `Oura ${opts.verb} error: ${statusLabel}${errSegment}`;
-    super(raw.slice(0, 1024));
+    super({ vendor: "Oura", ...opts });
     this.name = "OuraApiError";
-    this.verb = opts.verb;
-    this.classification = opts.classification;
-    this.httpStatus = opts.httpStatus;
-    this.reason = opts.reason;
-    this.upstreamError = opts.upstreamError;
   }
 }
 
@@ -92,22 +49,10 @@ export class OuraApiError extends Error {
  * surfaces the reconnect prompt.
  */
 export function isInvalidGrant(err: unknown): boolean {
-  if (err instanceof OuraApiError) {
-    if (err.httpStatus !== 400) return false;
-    if (err.upstreamError === "invalid_grant") return true;
-    return /\binvalid_grant\b/.test(err.message);
-  }
-  const msg = err instanceof Error ? err.message : String(err);
-  return /Oura\s+\w+\s+error:\s*400\b[\s\S]*\binvalid_grant\b/.test(msg);
+  return isOAuthInvalidGrant(err, "Oura");
 }
 
 export function classifyOuraError(err: unknown): OuraClassification {
   if (isInvalidGrant(err)) return "reauth_required";
-  if (err instanceof OuraApiError) return err.classification;
-  const msg = err instanceof Error ? err.message : String(err);
-  const m = /Oura\s+\w+\s+error:\s*(\d+)/.exec(msg);
-  if (!m) return "transient";
-  const status = Number.parseInt(m[1]!, 10);
-  if (!Number.isFinite(status)) return "transient";
-  return classifyOuraResponse(status).classification;
+  return classifyIntegrationError(err, "Oura");
 }
diff --git a/src/lib/oura/sync.ts b/src/lib/oura/sync.ts
index cfdafba35..58d110e54 100644
--- a/src/lib/oura/sync.ts
+++ b/src/lib/oura/sync.ts
@@ -23,6 +23,7 @@ import { getEvent } from "@/lib/logging/context";
 import {
   recordSyncFailure,
   recordSyncSuccess,
+  toFailureKind,
   type FailureKind,
 } from "@/lib/integrations/status";
 import {
@@ -50,10 +51,7 @@ import { OuraApiError, classifyOuraError } from "./response-classifier";
 export const OURA_SYNC_LOOKBACK_DAYS = 7;
 
 export function classifyOuraFailure(err: unknown): FailureKind {
-  const c = classifyOuraError(err);
-  if (c === "reauth_required") return "reauth_required";
-  if (c === "persistent") return "persistent";
-  return "transient";
+  return toFailureKind(classifyOuraError(err));
 }
 
 function ymd(d: Date): string {
diff --git a/src/lib/polar/__tests__/sync.test.ts b/src/lib/polar/__tests__/sync.test.ts
index c2bebb1a1..dda649bf6 100644
--- a/src/lib/polar/__tests__/sync.test.ts
+++ b/src/lib/polar/__tests__/sync.test.ts
@@ -30,7 +30,8 @@ vi.mock("@/lib/db", () => ({
   prisma: { measurement: { upsert: upsertMock } },
 }));
 
-vi.mock("@/lib/integrations/status", () => ({
+vi.mock("@/lib/integrations/status", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("@/lib/integrations/status")>()),
   recordSyncSuccess: recordSuccessMock,
   recordSyncFailure: recordFailureMock,
 }));
diff --git a/src/lib/polar/response-classifier.ts b/src/lib/polar/response-classifier.ts
index 7ec824425..30297e60b 100644
--- a/src/lib/polar/response-classifier.ts
+++ b/src/lib/polar/response-classifier.ts
@@ -1,9 +1,10 @@
 /**
  * v1.17.0 (F4) — off-response classifier for Polar AccessLink replies.
  *
- * Mirrors the WHOOP classifier (`src/lib/whoop/response-classifier.ts`): Polar
- * signals failure through the HTTP status code, so the classifier is
- * status-driven.
+ * Polar signals failure through the HTTP status code, so the classification is
+ * status-driven. The shared core lives in
+ * `src/lib/integrations/http-status-classifier.ts`; this module re-exports it
+ * under the Polar-specific names callers already use.
  *
  *   - `success`         → HTTP 2xx (incl. 204 No Content — Polar returns 204
  *                         when a collection window holds no records).
@@ -15,63 +16,26 @@
  *                         mismatch that a retry won't fix.
  */
 
-export type PolarClassification =
-  | "success"
-  | "transient"
-  | "reauth_required"
-  | "persistent";
+import {
+  classifyHttpStatus,
+  classifyIntegrationError,
+  IntegrationApiError,
+  type ClassifiedHttpResponse,
+  type IntegrationClassification,
+} from "@/lib/integrations/http-status-classifier";
 
-export interface ClassifiedPolarResponse {
-  classification: PolarClassification;
-  httpStatus: number | undefined;
-  reason: string;
-}
+export type PolarClassification = IntegrationClassification;
+
+export type ClassifiedPolarResponse = ClassifiedHttpResponse;
 
 export function classifyPolarResponse(
   httpStatus: number,
 ): ClassifiedPolarResponse {
-  if (httpStatus >= 200 && httpStatus < 300) {
-    return { classification: "success", httpStatus, reason: "ok" };
-  }
-  if (httpStatus === 429) {
-    return { classification: "transient", httpStatus, reason: "http_429" };
-  }
-  if (httpStatus === 401 || httpStatus === 403) {
-    return {
-      classification: "reauth_required",
-      httpStatus,
-      reason: `http_${httpStatus}`,
-    };
-  }
-  if (httpStatus >= 400 && httpStatus < 500) {
-    return {
-      classification: "persistent",
-      httpStatus,
-      reason: `http_${httpStatus}`,
-    };
-  }
-  if (httpStatus >= 500 && httpStatus < 600) {
-    return {
-      classification: "transient",
-      httpStatus,
-      reason: `http_${httpStatus}`,
-    };
-  }
-  return {
-    classification: "transient",
-    httpStatus,
-    reason: `http_${httpStatus}_unknown`,
-  };
+  return classifyHttpStatus(httpStatus);
 }
 
-/** Typed error carrying the classification verdict. Mirrors `WhoopApiError`. */
-export class PolarApiError extends Error {
-  readonly classification: PolarClassification;
-  readonly httpStatus: number | undefined;
-  readonly reason: string;
-  readonly verb: string;
-  readonly upstreamError: string | undefined;
-
+/** Typed error carrying the classification verdict. Extends the shared base. */
+export class PolarApiError extends IntegrationApiError {
   constructor(opts: {
     verb: string;
     classification: PolarClassification;
@@ -79,17 +43,8 @@ export class PolarApiError extends Error {
     reason: string;
     upstreamError?: string;
   }) {
-    const statusLabel =
-      typeof opts.httpStatus === "number" ? opts.httpStatus : "?";
-    const errSegment = opts.upstreamError ? ` - ${opts.upstreamError}` : "";
-    const raw = `Polar ${opts.verb} error: ${statusLabel}${errSegment}`;
-    super(raw.slice(0, 1024));
+    super({ vendor: "Polar", ...opts });
     this.name = "PolarApiError";
-    this.verb = opts.verb;
-    this.classification = opts.classification;
-    this.httpStatus = opts.httpStatus;
-    this.reason = opts.reason;
-    this.upstreamError = opts.upstreamError;
   }
 }
 
@@ -100,11 +55,5 @@ export class PolarApiError extends Error {
  * caller that lost the prototype across a pg-boss retry.
  */
 export function classifyPolarError(err: unknown): PolarClassification {
-  if (err instanceof PolarApiError) return err.classification;
-  const msg = err instanceof Error ? err.message : String(err);
-  const m = /Polar\s+\w+\s+error:\s*(\d+)/.exec(msg);
-  if (!m) return "transient";
-  const status = Number.parseInt(m[1]!, 10);
-  if (!Number.isFinite(status)) return "transient";
-  return classifyPolarResponse(status).classification;
+  return classifyIntegrationError(err, "Polar");
 }
diff --git a/src/lib/polar/sync.ts b/src/lib/polar/sync.ts
index 329b02a27..38ec71e69 100644
--- a/src/lib/polar/sync.ts
+++ b/src/lib/polar/sync.ts
@@ -26,6 +26,7 @@ import { getEvent } from "@/lib/logging/context";
 import {
   recordSyncFailure,
   recordSyncSuccess,
+  toFailureKind,
   type FailureKind,
 } from "@/lib/integrations/status";
 import {
@@ -47,10 +48,7 @@ import { PolarApiError, classifyPolarError } from "./response-classifier";
 
 /** Map a Polar error onto the shared integration-ledger failure kind. */
 export function classifyPolarFailure(err: unknown): FailureKind {
-  const c = classifyPolarError(err);
-  if (c === "reauth_required") return "reauth_required";
-  if (c === "persistent") return "persistent";
-  return "transient";
+  return toFailureKind(classifyPolarError(err));
 }
 
 /** One mapped reading with its `externalId` resolved. */