Prevent error redirect loops with beforeEach circuit breaker

This adds a circuit breaker for uncaught failures in beforeEach. The first failure still goes through the normal ERROR/RESTART recovery path; a second consecutive failure redirects to the static error page instead of looping.
- New before-each-error-recovery module tracks recovery attempts in sessionStorage (with an in-memory fallback).
- ERROR/RESTART routes skip normal guard logic so the counter can accumulate across bounce-backs.
- The counter clears only after a fully successful navigation.
- redirectToStaticErrorPage centralizes hard-error bailout: logs, clears poisoned sessionStorage keys (submittedState, heritage redirect count, recovery count, externalParameterState), then navigates to /fmg/static/error.
- The static error page RESTART flow clears the same sessionStorage keys so bad state does not re-enter the funnel.
- Session storage key strings are centralized in session-storage.js.
- Unit tests cover recovery counting, bailout clearing, and navigation fallbacks.
Expected impact: Stops repeated ERROR → RESTART → ERROR cycles (including corrupt submittedState JSON.parse failures and recurring automation errors in us-east-1/us-east-2) by bailing out to the static error page after one failed recovery attempt.

public/static/error/index.html

@@ -258,10 +258,36 @@ body {
                 return match?.value;
             }
 
+            // Refactor opportunity: sessionStorage keys and cookie names below are duplicated from the
+            // Vue app because this static page is not webpack-bundled. Canonical sources:
+            //   - src/constants/session-storage.js (sessionStorageKeyConstants)
+            //   - src/constants/cookie-names.js (cookieNames; env-suffixed funnel cookies)
+            //   - src/router/methods/error.js (clearBailoutSessionStorage — keep in sync on bailout keys)
+            // Options: build-time inject into this file, shared plain JS under public/static/, or generate
+            // from constants during CI. Until then, update all three places when keys change.
             function clearApplicationData() {
                 window.localStorage.removeItem('vuex');
 
+                // Keys match sessionStorageKeyConstants in src/constants/session-storage.js and
+                // clearBailoutSessionStorage() in src/router/methods/error.js — keep in sync.
+                const sessionStorageKeysToClear = [
+                    'submittedState',
+                    'heritageSuppressRedirectCount',
+                    'beforeEachErrorRecoveryCount',
+                    'externalParameterState',
+                ];
+                // Clear sessionStorage keys that can re-poison the funnel on re-entry.
+                sessionStorageKeysToClear.forEach((key) => {
+                    try {
+                        window.sessionStorage.removeItem(key);
+                    } catch {
+                        // sessionStorage unavailable
+                    }
+                });
+
                 const environmentData = getCurrentEnvironmentData();
+                // Funnel cookie prefixes match cookie-names.js; suffix is environmentData.name here
+                // (equivalent to applicationConfig.CURRENT_ENVIRONMENT in the Vue app).
                 const cookieNames = [
                     `FunnelUserId-${environmentData?.name}`,
                     `FunnelSessionKey-${environmentData?.name}`,

src/constants/session-storage.js

@@ -2,4 +2,8 @@ export const sessionStorageKeyConstants = {
     SUBMITTED_STATE: "submittedState",
     /** Counts SuppressConceptFunnel → heritage redirects to avoid an infinite loop in one tab session. */
     HERITAGE_SUPPRESS_REDIRECT_COUNT: "heritageSuppressRedirectCount",
+    /** Counts beforeEach uncaught-exception recovery attempts to avoid an infinite ERROR redirect loop. */
+    BEFORE_EACH_ERROR_RECOVERY_COUNT: "beforeEachErrorRecoveryCount",
+    /** Persists deep-link / querystring funnel entry state across navigations. */
+    EXTERNAL_PARAMETER_STATE: "externalParameterState",
 };

src/router/methods/before-each-error-recovery.js

@@ -0,0 +1,51 @@
+import { sessionStorageKeyConstants } from "@/constants/session-storage";
+
+const recoveryKey = sessionStorageKeyConstants.BEFORE_EACH_ERROR_RECOVERY_COUNT;
+
+/** Used when sessionStorage is missing, throws, or does not persist (e.g. some bots). */
+let inMemoryRecoveryCount = 0;
+
+export function getBeforeEachErrorRecoveryCount() {
+    try {
+        const stored = window.sessionStorage?.getItem(recoveryKey);
+        if (stored !== null && stored !== undefined) {
+            return Number(stored) || 0;
+        }
+    } catch {
+        // sessionStorage unavailable; use in-memory fallback
+    }
+
+    return inMemoryRecoveryCount;
+}
+
+export function incrementBeforeEachErrorRecoveryCount() {
+    const nextCount = getBeforeEachErrorRecoveryCount() + 1;
+    inMemoryRecoveryCount = nextCount;
+
+    try {
+        window.sessionStorage?.setItem(recoveryKey, String(nextCount));
+    } catch {
+        // in-memory count already updated
+    }
+
+    return nextCount;
+}
+
+export function clearBeforeEachErrorRecoveryCount() {
+    inMemoryRecoveryCount = 0;
+
+    try {
+        window.sessionStorage?.removeItem(recoveryKey);
+    } catch {
+        // in-memory count already cleared
+    }
+}
+
+export function hasBeforeEachErrorRecoveryBeenAttempted() {
+    return getBeforeEachErrorRecoveryCount() >= 1;
+}
+
+/** Test-only: resets in-memory and sessionStorage recovery state between unit tests. */
+export function resetBeforeEachErrorRecoveryStateForTests() {
+    clearBeforeEachErrorRecoveryCount();
+}

src/router/methods/before-each-error-recovery.spec.js

@@ -0,0 +1,80 @@
+import {
+    clearBeforeEachErrorRecoveryCount,
+    getBeforeEachErrorRecoveryCount,
+    hasBeforeEachErrorRecoveryBeenAttempted,
+    incrementBeforeEachErrorRecoveryCount,
+    resetBeforeEachErrorRecoveryStateForTests,
+} from "./before-each-error-recovery";
+import { sessionStorageKeyConstants } from "@/constants/session-storage";
+
+describe("router/methods/before-each-error-recovery", () => {
+    const recoveryKey = sessionStorageKeyConstants.BEFORE_EACH_ERROR_RECOVERY_COUNT;
+    let originalSessionStorage;
+
+    beforeEach(() => {
+        resetBeforeEachErrorRecoveryStateForTests();
+        originalSessionStorage = window.sessionStorage;
+    });
+
+    afterEach(() => {
+        Object.defineProperty(window, "sessionStorage", {
+            configurable: true,
+            value: originalSessionStorage,
+        });
+        resetBeforeEachErrorRecoveryStateForTests();
+    });
+
+    it("reads and writes recovery count via sessionStorage when available", () => {
+        incrementBeforeEachErrorRecoveryCount();
+
+        expect(window.sessionStorage.getItem(recoveryKey)).toBe("1");
+        expect(getBeforeEachErrorRecoveryCount()).toBe(1);
+        expect(hasBeforeEachErrorRecoveryBeenAttempted()).toBe(true);
+    });
+
+    it("clears sessionStorage and in-memory count", () => {
+        incrementBeforeEachErrorRecoveryCount();
+        clearBeforeEachErrorRecoveryCount();
+
+        expect(window.sessionStorage.getItem(recoveryKey)).toBeNull();
+        expect(getBeforeEachErrorRecoveryCount()).toBe(0);
+        expect(hasBeforeEachErrorRecoveryBeenAttempted()).toBe(false);
+    });
+
+    it("uses in-memory count when sessionStorage getItem throws", () => {
+        Object.defineProperty(window, "sessionStorage", {
+            configurable: true,
+            value: {
+                getItem: () => {
+                    throw new Error("sessionStorage blocked");
+                },
+                setItem: jest.fn(),
+                removeItem: jest.fn(),
+            },
+        });
+
+        incrementBeforeEachErrorRecoveryCount();
+        incrementBeforeEachErrorRecoveryCount();
+
+        expect(hasBeforeEachErrorRecoveryBeenAttempted()).toBe(true);
+        expect(getBeforeEachErrorRecoveryCount()).toBe(2);
+    });
+
+    it("uses in-memory count when sessionStorage setItem throws", () => {
+        Object.defineProperty(window, "sessionStorage", {
+            configurable: true,
+            value: {
+                getItem: () => null,
+                setItem: () => {
+                    throw new Error("sessionStorage blocked");
+                },
+                removeItem: jest.fn(),
+            },
+        });
+
+        incrementBeforeEachErrorRecoveryCount();
+
+        expect(hasBeforeEachErrorRecoveryBeenAttempted()).toBe(true);
+        expect(getBeforeEachErrorRecoveryCount()).toBe(1);
+    });
+});

src/router/methods/before-each.js

@@ -9,7 +9,16 @@ import { routeData, FUNNEL_START_PAGE } from "@/router/constants/routes";
 import { runExperiments } from "@/router/methods/helpers/run-experiments";
 import { navigateToHeritageFunnel } from "@/helpers/heritage-integration/navigation-helper";
 
-import { handleSoftError, handleHardError } from "@/router/methods/error";
+import {
+    handleSoftError,
+    handleHardError,
+    redirectToStaticErrorPage,
+} from "@/router/methods/error";
+import {
+    clearBeforeEachErrorRecoveryCount,
+    hasBeforeEachErrorRecoveryBeenAttempted,
+    incrementBeforeEachErrorRecoveryCount,
+} from "@/router/methods/before-each-error-recovery";
 import { checkPagePrerequisites } from "@/router/methods/page-prerequisites";
 import { checkLogParam } from "@/helpers/debug-log-helper";
 import { debugLog } from "@/helpers/debug-log-helper";
@@ -19,8 +28,21 @@ import router from "@/router";
 
 const MAX_HERITAGE_SUPPRESS_REDIRECTS_PER_SESSION = 5;
 
+function isRecoveryRoute(routeName) {
+    return routeName === routeData.ERROR.name || routeName === routeData.RESTART.name;
+}
+
 export async function beforeEach(to, from) {
     try {
+        if (isRecoveryRoute(to.name)) {
+            debugLog(`--- before-each.js recovery route ${to.name} ---`);
+            // Do NOT clear the recovery counter here. The counter must accumulate across
+            // consecutive failures that bounce through the ERROR/RESTART route so the
+            // circuit breaker can trip and fall back to the static error page. It is only
+            // cleared after a fully successful guard pass (end of try block).
+            return;
+        }
+
         await analyticsMixin.methods.validateSession();
 
         // prettier-ignore
@@ -63,7 +85,7 @@ export async function beforeEach(to, from) {
             }
         }
 
-        // Ensure session has not expired
+        // Ensure session has not expired - not primary check for session expiration and uses FunnelSessionInfo-{environment} cookie.
         if (getFunnelCookie() !== null && !isSavedSessionStillActive()) {
             const errorPayload = {
                 cause: "expired session",
@@ -141,18 +163,31 @@ export async function beforeEach(to, from) {
         {
             debugLog("--- before-each.js end ---");
         }
+
+        clearBeforeEachErrorRecoveryCount();
     } catch (error) {
         const errorPayload = {
             cause: "Uncaught exception in `beforeEach`.",
             currentPage: from?.name,
             nextPage: to?.name,
+            errorMessage: error?.message,
+            errorStack: error?.stack,
         };
 
         console.log(error);
+        global.$logger?.logError("beforeEach uncaught exception", errorPayload);
+
+        if (to.name === routeData.ERROR.name || hasBeforeEachErrorRecoveryBeenAttempted()) {
+            clearBeforeEachErrorRecoveryCount();
+            await redirectToStaticErrorPage(errorPayload);
+            return false;
+        }
+
+        incrementBeforeEachErrorRecoveryCount();
 
         // Eject user from Vue app in this scenario and clear localstorage.
         await handleHardError(errorPayload);
-        return;
+        return false;
     }
 }
 

src/router/methods/before-each.spec.js

@@ -0,0 +1,257 @@
+import analyticsMixin from "@/mixins/analytics-mixin";
+import { runExperiments } from "@/router/methods/helpers/run-experiments";
+import { handleHardError, redirectToStaticErrorPage } from "@/router/methods/error";
+import { sessionStorageKeyConstants } from "@/constants/session-storage";
+import { routeData } from "@/router/constants/routes";
+import { debugLog } from "@/helpers/debug-log-helper";
+
+jest.mock("@/mixins/analytics-mixin", () => ({
+    __esModule: true,
+    default: {
+        methods: {
+            validateSession: jest.fn(() => Promise.resolve()),
+        },
+    },
+}));
+
+jest.mock("@/router/methods/helpers/run-experiments", () => ({
+    runExperiments: jest.fn(() => Promise.resolve()),
+}));
+
+jest.mock("@/helpers/heritage-integration/cookie-helper", () => ({
+    getFunnelCookie: jest.fn(() => null),
+    updateOrCreateFunnelCookie: jest.fn(),
+}));
+
+jest.mock("@/helpers/heritage-integration/session-helper", () => ({
+    isSavedSessionStillActive: jest.fn(() => true),
+    getDateForSavedSessionTimeout: jest.fn(() => "2099-01-01T00:00:00.000Z"),
+}));
+
+jest.mock("@/helpers/heritage-integration/navigation-helper", () => ({
+    navigateToHeritageFunnel: jest.fn(),
+}));
+
+jest.mock("@/router/methods/helpers/handle-heritage-return", () => ({
+    handleHeritageReturn: jest.fn(() => Promise.resolve()),
+}));
+
+jest.mock("@/router/methods/page-prerequisites", () => ({
+    checkPagePrerequisites: jest.fn(() => Promise.resolve(true)),
+}));
+
+jest.mock("@/helpers/debug-log-helper", () => ({
+    debugLog: jest.fn(),
+    checkLogParam: jest.fn(),
+}));
+
+jest.mock("@/router/methods/error", () => ({
+    handleSoftError: jest.fn(() => Promise.resolve()),
+    handleHardError: jest.fn(() => Promise.resolve()),
+    redirectToStaticErrorPage: jest.fn(() => Promise.resolve()),
+}));
+
+jest.mock("@/router", () => ({
+    __esModule: true,
+    default: {
+        push: jest.fn(),
+    },
+}));
+
+import { beforeEach as routerBeforeEach } from "./before-each";
+import {
+    hasBeforeEachErrorRecoveryBeenAttempted,
+    incrementBeforeEachErrorRecoveryCount,
+    resetBeforeEachErrorRecoveryStateForTests,
+} from "./before-each-error-recovery";
+
+describe("router/methods/before-each", () => {
+    const recoveryKey = sessionStorageKeyConstants.BEFORE_EACH_ERROR_RECOVERY_COUNT;
+
+    beforeEach(() => {
+        jest.clearAllMocks();
+        resetBeforeEachErrorRecoveryStateForTests();
+        window.sessionStorage.removeItem(recoveryKey);
+        window.sessionStorage.removeItem(sessionStorageKeyConstants.SUBMITTED_STATE);
+        analyticsMixin.methods.validateSession.mockResolvedValue(undefined);
+        debugLog.mockImplementation(() => undefined);
+        global.$logger = {
+            logError: jest.fn(),
+        };
+    });
+
+    it("skips validateSession and runExperiments when navigating to ERROR", async () => {
+        await routerBeforeEach({ name: routeData.ERROR.name }, { name: routeData.VEHICLE.name });
+
+        expect(analyticsMixin.methods.validateSession).not.toHaveBeenCalled();
+        expect(runExperiments).not.toHaveBeenCalled();
+    });
+
+    it("skips validateSession and runExperiments when navigating to RESTART", async () => {
+        await routerBeforeEach({ name: routeData.RESTART.name }, { name: routeData.VEHICLE.name });
+
+        expect(analyticsMixin.methods.validateSession).not.toHaveBeenCalled();
+        expect(runExperiments).not.toHaveBeenCalled();
+    });
+
+    it("clears recovery counter after successful funnel navigation", async () => {
+        incrementBeforeEachErrorRecoveryCount();
+        expect(hasBeforeEachErrorRecoveryBeenAttempted()).toBe(true);
+
+        await routerBeforeEach(
+            { name: routeData.VEHICLE_DAMAGE.name },
+            { name: routeData.VEHICLE.name }
+        );
+
+        expect(hasBeforeEachErrorRecoveryBeenAttempted()).toBe(false);
+        expect(window.sessionStorage.getItem(recoveryKey)).toBeNull();
+    });
+
+    it("preserves recovery counter when passing through the ERROR recovery route", async () => {
+        incrementBeforeEachErrorRecoveryCount();
+        expect(hasBeforeEachErrorRecoveryBeenAttempted()).toBe(true);
+
+        await routerBeforeEach({ name: routeData.ERROR.name }, { name: routeData.VEHICLE.name });
+
+        // The counter must survive the ERROR bounce so consecutive failures can trip the
+        // circuit breaker; it is only cleared after a fully successful guard pass.
+        expect(hasBeforeEachErrorRecoveryBeenAttempted()).toBe(true);
+        expect(window.sessionStorage.getItem(recoveryKey)).toBe("1");
+    });
+
+    it("runs validateSession on a normal funnel page", async () => {
+        await routerBeforeEach(
+            { name: routeData.VEHICLE_DAMAGE.name },
+            { name: routeData.VEHICLE.name }
+        );
+
+        expect(analyticsMixin.methods.validateSession).toHaveBeenCalled();
+        expect(runExperiments).toHaveBeenCalledWith(routeData.VEHICLE_DAMAGE.name);
+    });
+
+    it("calls handleHardError once on uncaught exception", async () => {
+        analyticsMixin.methods.validateSession.mockRejectedValue(new Error("session failure"));
+
+        const result = await routerBeforeEach(
+            { name: routeData.VEHICLE_DAMAGE.name },
+            { name: routeData.VEHICLE.name }
+        );
+
+        expect(handleHardError).toHaveBeenCalledTimes(1);
+        expect(handleHardError).toHaveBeenCalledWith(
+            expect.objectContaining({
+                cause: "Uncaught exception in `beforeEach`.",
+                errorMessage: "session failure",
+                errorStack: expect.any(String),
+            })
+        );
+        expect(global.$logger.logError).toHaveBeenCalledWith(
+            "beforeEach uncaught exception",
+            expect.objectContaining({ errorMessage: "session failure" })
+        );
+        expect(redirectToStaticErrorPage).not.toHaveBeenCalled();
+        expect(window.sessionStorage.getItem(recoveryKey)).toBe("1");
+        expect(result).toBe(false);
+    });
+
+    it("redirects to static error page when exception occurs on ERROR route", async () => {
+        debugLog.mockImplementation(() => {
+            throw new Error("recovery route failure");
+        });
+
+        const result = await routerBeforeEach(
+            { name: routeData.ERROR.name },
+            { name: routeData.VEHICLE.name }
+        );
+
+        expect(global.$logger.logError).toHaveBeenCalledWith(
+            "beforeEach uncaught exception",
+            expect.objectContaining({
+                errorMessage: "recovery route failure",
+                nextPage: routeData.ERROR.name,
+            })
+        );
+        expect(redirectToStaticErrorPage).toHaveBeenCalledWith(
+            expect.objectContaining({
+                cause: "Uncaught exception in `beforeEach`.",
+                errorMessage: "recovery route failure",
+                nextPage: routeData.ERROR.name,
+            })
+        );
+        expect(handleHardError).not.toHaveBeenCalled();
+        expect(window.sessionStorage.getItem(recoveryKey)).toBeNull();
+        expect(result).toBe(false);
+    });
+
+    it("redirects to static error page on second uncaught exception in session", async () => {
+        analyticsMixin.methods.validateSession.mockRejectedValue(new Error("session failure"));
+        window.sessionStorage.setItem(recoveryKey, "1");
+
+        const result = await routerBeforeEach(
+            { name: routeData.VEHICLE_DAMAGE.name },
+            { name: routeData.VEHICLE.name }
+        );
+
+        expect(global.$logger.logError).toHaveBeenCalledWith(
+            "beforeEach uncaught exception",
+            expect.objectContaining({ cause: "Uncaught exception in `beforeEach`." })
+        );
+        expect(redirectToStaticErrorPage).toHaveBeenCalled();
+        expect(handleHardError).not.toHaveBeenCalled();
+        expect(window.sessionStorage.getItem(recoveryKey)).toBeNull();
+        expect(result).toBe(false);
+    });
+
+    it("redirects to static error page on second failure when sessionStorage throws", async () => {
+        analyticsMixin.methods.validateSession.mockRejectedValue(new Error("session failure"));
+
+        const storageBlockedError = new Error("sessionStorage blocked");
+        const underlyingStorage = window.sessionStorage;
+        Object.defineProperty(window, "sessionStorage", {
+            configurable: true,
+            value: {
+                getItem(key) {
+                    if (key === recoveryKey) {
+                        throw storageBlockedError;
+                    }
+                    return underlyingStorage.getItem(key);
+                },
+                setItem(key, value) {
+                    if (key === recoveryKey) {
+                        throw storageBlockedError;
+                    }
+                    underlyingStorage.setItem(key, value);
+                },
+                removeItem(key) {
+                    if (key === recoveryKey) {
+                        throw storageBlockedError;
+                    }
+                    underlyingStorage.removeItem(key);
+                },
+            },
+        });
+
+        await routerBeforeEach(
+            { name: routeData.VEHICLE_DAMAGE.name },
+            { name: routeData.VEHICLE.name }
+        );
+        expect(handleHardError).toHaveBeenCalledTimes(1);
+        expect(redirectToStaticErrorPage).not.toHaveBeenCalled();
+
+        jest.clearAllMocks();
+
+        const result = await routerBeforeEach(
+            { name: routeData.VEHICLE_DAMAGE.name },
+            { name: routeData.VEHICLE.name }
+        );
+
+        expect(redirectToStaticErrorPage).toHaveBeenCalled();
+        expect(handleHardError).not.toHaveBeenCalled();
+        expect(result).toBe(false);
+
+        Object.defineProperty(window, "sessionStorage", {
+            configurable: true,
+            value: underlyingStorage,
+        });
+    });
+});

src/router/methods/error.js

@@ -3,9 +3,41 @@ import { routeData } from "@/router/constants/routes";
 import router from "@/router";
 import store from "@/store";
 import { storeActions } from "@/constants/store-actions";
+import { sessionStorageKeyConstants } from "@/constants/session-storage";
 import { deleteFunnelCookie } from "@/helpers/heritage-integration/cookie-helper";
+import { clearBeforeEachErrorRecoveryCount } from "@/router/methods/before-each-error-recovery";
 import experimentMixin from "../../mixins/experiment-mixin";
 
+const STATIC_ERROR_PAGE_PATH = "/fmg/static/error";
+
+/** Clears sessionStorage keys that can re-poison the funnel after a bailout. */
+export function clearBailoutSessionStorage() {
+    clearBeforeEachErrorRecoveryCount();
+
+    try {
+        window.sessionStorage?.removeItem(sessionStorageKeyConstants.SUBMITTED_STATE);
+        window.sessionStorage?.removeItem(
+            sessionStorageKeyConstants.HERITAGE_SUPPRESS_REDIRECT_COUNT
+        );
+        window.sessionStorage?.removeItem(sessionStorageKeyConstants.EXTERNAL_PARAMETER_STATE);
+    } catch {
+        // sessionStorage unavailable
+    }
+}
+
+export async function redirectToStaticErrorPage(errorPayload) {
+    await logErrorToDataLayerAndLogger("redirectToStaticErrorPage", errorPayload, null);
+    clearBailoutSessionStorage();
+
+    // Prefer top-level navigation so the static page loads outside any iframe wrapper.
+    // Assigning window.top.location throws SecurityError when cross-origin; fall back to this frame.
+    try {
+        window.top.location = STATIC_ERROR_PAGE_PATH;
+    } catch {
+        window.location = STATIC_ERROR_PAGE_PATH;
+    }
+}
+
 export async function handleSoftError(errorPayload, forceRestart = false) {
     if (forceRestart) {
         await store.dispatch(storeActions.RESET_STATE);
@@ -27,8 +59,7 @@ export async function handleHardError(errorPayload) {
         );
 
         if (isInStaticErrorExperiment) {
-            logErrorToDataLayerAndLogger("handleHardError", errorPayload, null);
-            window.top.location = "/fmg/static/error";
+            await redirectToStaticErrorPage(errorPayload);
             return;
         } else {
             await handleSoftError(errorPayload, true);

src/router/methods/error.spec.js

@@ -1,10 +1,11 @@
-import { handleSoftError, handleHardError } from "./error";
+import { handleSoftError, handleHardError, redirectToStaticErrorPage } from "./error";
 import router from "@/router";
 import store from "@/store";
 import analyticsMixin from "@/mixins/analytics-mixin";
 import experimentMixin from "../../mixins/experiment-mixin";
 import { deleteFunnelCookie } from "@/helpers/heritage-integration/cookie-helper";
 import { storeActions } from "@/constants/store-actions";
+import { sessionStorageKeyConstants } from "@/constants/session-storage";
 import { routeData } from "@/router/constants/routes";
 
 jest.mock("@/router", () => ({
@@ -98,6 +99,126 @@ describe("router/methods/error", () => {
         });
     });
 
+    describe("redirectToStaticErrorPage", () => {
+        let topLocationValue;
+
+        beforeEach(() => {
+            topLocationValue = undefined;
+            Object.defineProperty(window, "top", {
+                configurable: true,
+                value: {},
+            });
+            Object.defineProperty(window.top, "location", {
+                configurable: true,
+                set(value) {
+                    topLocationValue = value;
+                },
+                get() {
+                    return topLocationValue;
+                },
+            });
+        });
+
+        it("logs and sets static error location", async () => {
+            await redirectToStaticErrorPage(errorPayload);
+
+            expect(analyticsMixin.methods.pushPageErrorToDataLayer).toHaveBeenCalledWith(
+                errorPayload
+            );
+            expect(global.$logger.logError).toHaveBeenCalledWith(
+                "redirectToStaticErrorPage: test cause",
+                errorPayload
+            );
+            expect(topLocationValue).toBe("/fmg/static/error");
+        });
+
+        it("clears bailout sessionStorage keys before navigating away", async () => {
+            window.sessionStorage.setItem(sessionStorageKeyConstants.SUBMITTED_STATE, "not-json");
+            window.sessionStorage.setItem(
+                sessionStorageKeyConstants.HERITAGE_SUPPRESS_REDIRECT_COUNT,
+                "3"
+            );
+            window.sessionStorage.setItem(
+                sessionStorageKeyConstants.BEFORE_EACH_ERROR_RECOVERY_COUNT,
+                "1"
+            );
+            window.sessionStorage.setItem(
+                sessionStorageKeyConstants.EXTERNAL_PARAMETER_STATE,
+                "{}"
+            );
+
+            await redirectToStaticErrorPage(errorPayload);
+
+            expect(
+                window.sessionStorage.getItem(sessionStorageKeyConstants.SUBMITTED_STATE)
+            ).toBeNull();
+            expect(
+                window.sessionStorage.getItem(
+                    sessionStorageKeyConstants.HERITAGE_SUPPRESS_REDIRECT_COUNT
+                )
+            ).toBeNull();
+            expect(
+                window.sessionStorage.getItem(
+                    sessionStorageKeyConstants.BEFORE_EACH_ERROR_RECOVERY_COUNT
+                )
+            ).toBeNull();
+            expect(
+                window.sessionStorage.getItem(sessionStorageKeyConstants.EXTERNAL_PARAMETER_STATE)
+            ).toBeNull();
+        });
+
+        it("falls back to window.location when window.top.location setter throws", async () => {
+            let windowLocationValue;
+            Object.defineProperty(window, "location", {
+                configurable: true,
+                set(value) {
+                    windowLocationValue = value;
+                },
+                get() {
+                    return windowLocationValue;
+                },
+            });
+            Object.defineProperty(window.top, "location", {
+                configurable: true,
+                set() {
+                    throw new Error("cross-origin frame");
+                },
+                get() {
+                    return undefined;
+                },
+            });
+
+            await redirectToStaticErrorPage(errorPayload);
+
+            expect(windowLocationValue).toBe("/fmg/static/error");
+            expect(topLocationValue).toBeUndefined();
+        });
+
+        it("awaits logging before navigating away", async () => {
+            const callOrder = [];
+            analyticsMixin.methods.pushPageErrorToDataLayer.mockImplementation(() => {
+                callOrder.push("datalayer");
+            });
+            global.$logger.logError.mockImplementation(() => {
+                callOrder.push("logger");
+            });
+            Object.defineProperty(window.top, "location", {
+                configurable: true,
+                set(value) {
+                    callOrder.push("navigate");
+                    topLocationValue = value;
+                },
+                get() {
+                    return topLocationValue;
+                },
+            });
+
+            await redirectToStaticErrorPage(errorPayload);
+
+            expect(callOrder).toEqual(["datalayer", "logger", "navigate"]);
+        });
+    });
+
     describe("handleHardError", () => {
         let topLocationValue;
 
@@ -131,7 +252,7 @@ describe("router/methods/error", () => {
                 errorPayload
             );
             expect(global.$logger.logError).toHaveBeenCalledWith(
-                "handleHardError: test cause",
+                "redirectToStaticErrorPage: test cause",
                 errorPayload
             );
             expect(topLocationValue).toBe("/fmg/static/error");

src/router/methods/route-logic/error.js

@@ -25,6 +25,8 @@ export async function errorBeforeEnter(to, from) {
 
     // If we've already encountered one error, clear session to avoid more.
     // Otherwise mark that we encountered an error here.
+    // Note: an earlier breaker also runs in before-each.js via before-each-error-recovery.js
+    // (consecutive uncaught guard failures before this route handler runs).
     if (store.getters.applicationUser.hasAlreadyTriggeredError) {
         const errorPayload = {
             cause: "Successive errors triggered.",

src/store/index.js

@@ -3733,7 +3733,7 @@ export const actions = {
         context.commit(storeMutations.UPDATE_EXPERIMENTS, experiments);
 
         //clear externalParameter session storage
-        window.sessionStorage.removeItem("externalParameterState");
+        window.sessionStorage.removeItem(sessionStorageKeyConstants.EXTERNAL_PARAMETER_STATE);
 
         //restore affiliate cookies
         context.commit(storeMutations.UPDATE_AFFILIATE_COOKIES, affiliateCookies);
@@ -4447,14 +4447,21 @@ function createExternalParameterDefaultState() {
     saveExternalParameterState(externalParameterDefaultState);
 }
 function getExternalParameterDefaultState() {
-    const externalParameterState = window.sessionStorage.getItem("externalParameterState");
+    const externalParameterState = window.sessionStorage.getItem(
+        sessionStorageKeyConstants.EXTERNAL_PARAMETER_STATE
+    );
     if (externalParameterState === null) {
         createExternalParameterDefaultState();
     }
-    return JSON.parse(window.sessionStorage.getItem("externalParameterState"));
+    return JSON.parse(
+        window.sessionStorage.getItem(sessionStorageKeyConstants.EXTERNAL_PARAMETER_STATE)
+    );
 }
 function saveExternalParameterState(externalParameterState) {
-    window.sessionStorage.setItem("externalParameterState", JSON.stringify(externalParameterState));
+    window.sessionStorage.setItem(
+        sessionStorageKeyConstants.EXTERNAL_PARAMETER_STATE,
+        JSON.stringify(externalParameterState)
+    );
 }
 
 const timeSlotCallFlags = {