diff --git a/src/app/accountRepository.test.ts b/src/app/accountRepository.test.ts
index abdb89b8..14156a1e 100644
--- a/src/app/accountRepository.test.ts
+++ b/src/app/accountRepository.test.ts
@@ -4,6 +4,7 @@ import {
   createCharacter,
   createLocalAccount,
   createOfflineSession,
+  clearSession,
   listCharacters,
   loadAccountBossCards,
   saveAccountBossCards,
@@ -12,6 +13,7 @@ import {
   loadCombatPresentationSettings,
   loginLocalAccount,
   restoreSession,
+  saveSession,
   updateCharacterActionBindings,
   updateCharacterEquipment,
   updateCharacterDungeonRunCheckpoint,
@@ -165,6 +167,31 @@ describe("local profile repository", () => {
     expect(restoreSession(storage)?.roles).toEqual([]);
   });
 
+  it("keeps a login across browser sessions and clears it on sign-out", () => {
+    const persistent = new MemoryStorage();
+    const firstTab = new MemoryStorage();
+    const nextTab = new MemoryStorage();
+    const session = { kind: "account" as const, ownerId: "account-1", displayName: "Healer", accessToken: "server-token", roles: ["gm" as const] };
+    saveSession(session, persistent, firstTab);
+
+    expect(firstTab.getItem(PROFILE_STORAGE_KEYS.session)).toBeNull();
+    expect(restoreSession(persistent, nextTab)).toMatchObject({ ...session, roles: [] });
+
+    clearSession(persistent, nextTab);
+    expect(restoreSession(persistent, nextTab)).toBeNull();
+  });
+
+  it("moves a previous tab-scoped session into persistent storage", () => {
+    const persistent = new MemoryStorage();
+    const previousTab = new MemoryStorage();
+    const session = { kind: "offline" as const, ownerId: "offline-roster", displayName: "Offline" };
+    previousTab.setItem(PROFILE_STORAGE_KEYS.session, JSON.stringify(session));
+
+    expect(restoreSession(persistent, previousTab)).toMatchObject(session);
+    expect(previousTab.getItem(PROFILE_STORAGE_KEYS.session)).toBeNull();
+    expect(restoreSession(persistent, new MemoryStorage())).toMatchObject(session);
+  });
+
   it("normalizes legacy profiles and persists progression atomically", () => {
     const storage = new MemoryStorage();
     storage.setItem(PROFILE_STORAGE_KEYS.database, JSON.stringify({
diff --git a/src/app/accountRepository.ts b/src/app/accountRepository.ts
index 25143c09..0b1a8abc 100644
--- a/src/app/accountRepository.ts
+++ b/src/app/accountRepository.ts
@@ -429,11 +429,25 @@ export function createOfflineSession(): PlayerSession {
   return { kind: "offline", ownerId: OFFLINE_OWNER_ID, displayName: "Offline" };
 }
 
-export function saveSession(session: PlayerSession, storage: StorageLike | null = browserSessionStorage()): void {
-  storage?.setItem(SESSION_KEY, JSON.stringify(session));
+export function saveSession(
+  session: PlayerSession,
+  storage: StorageLike | null = browserLocalStorage(),
+  transientStorage: StorageLike | null = browserSessionStorage(),
+): void {
+  const serialized = JSON.stringify(session);
+  try {
+    if (storage) {
+      storage.setItem(SESSION_KEY, serialized);
+      if (transientStorage !== storage) {
+        try { transientStorage?.removeItem(SESSION_KEY); } catch { /* Storage may be disabled. */ }
+      }
+      return;
+    }
+  } catch { /* Fall back to tab-scoped storage when persistent storage is unavailable. */ }
+  try { transientStorage?.setItem(SESSION_KEY, serialized); } catch { /* Storage may be disabled. */ }
 }
 
-export function restoreSession(storage: StorageLike | null = browserSessionStorage()): PlayerSession | null {
+function readStoredSession(storage: StorageLike | null): PlayerSession | null {
   if (!storage) return null;
   try {
     const session = JSON.parse(storage.getItem(SESSION_KEY) ?? "null") as Partial<PlayerSession> | null;
@@ -451,8 +465,26 @@ export function restoreSession(storage: StorageLike | null = browserSessionStora
   }
 }
 
-export function clearSession(storage: StorageLike | null = browserSessionStorage()): void {
-  storage?.removeItem(SESSION_KEY);
+export function restoreSession(
+  storage: StorageLike | null = browserLocalStorage(),
+  transientStorage: StorageLike | null = browserSessionStorage(),
+): PlayerSession | null {
+  const persistent = readStoredSession(storage);
+  if (persistent) return persistent;
+  if (transientStorage === storage) return null;
+  const transient = readStoredSession(transientStorage);
+  if (transient) saveSession(transient, storage, transientStorage);
+  return transient;
+}
+
+export function clearSession(
+  storage: StorageLike | null = browserLocalStorage(),
+  transientStorage: StorageLike | null = browserSessionStorage(),
+): void {
+  try { storage?.removeItem(SESSION_KEY); } catch { /* Storage may be disabled. */ }
+  if (transientStorage !== storage) {
+    try { transientStorage?.removeItem(SESSION_KEY); } catch { /* Storage may be disabled. */ }
+  }
 }
 
 export function listCharacters(ownerId: string, storage: StorageLike | null = browserLocalStorage()): CharacterProfile[] {
diff --git a/src/app/onlineAccountClient.ts b/src/app/onlineAccountClient.ts
index cb461ef4..4e0a7481 100644
--- a/src/app/onlineAccountClient.ts
+++ b/src/app/onlineAccountClient.ts
@@ -38,6 +38,10 @@ class OnlineApiError extends Error {
   }
 }
 
+export function isOnlineAuthenticationError(error: unknown): boolean {
+  return error instanceof OnlineApiError && error.status === 401;
+}
+
 let activeSession: PlayerSession | null = null;
 let suppressUpload = false;
 let pendingCharacters: CharacterProfile[] | null = null;
@@ -135,11 +139,11 @@ function queueCloudSave(ownerId: string, characters: readonly CharacterProfile[]
 
 setRosterChangeListener(queueCloudSave);
 
-export function activateOnlineSession(session: PlayerSession): void {
-  if (activeSession?.ownerId !== session.ownerId && saveTimer) {
+export function activateOnlineSession(session: PlayerSession | null): void {
+  if (activeSession?.ownerId !== session?.ownerId && saveTimer) {
     clearTimeout(saveTimer); saveTimer = null; flushCloudSave();
   }
-  activeSession = session.accessToken ? session : null;
+  activeSession = session?.accessToken ? session : null;
 }
 
 export function retryCloudSave(): void {
diff --git a/src/app/shellStore.ts b/src/app/shellStore.ts
index b6444a06..d817a488 100644
--- a/src/app/shellStore.ts
+++ b/src/app/shellStore.ts
@@ -56,6 +56,7 @@ import { manastormShellRuntime } from "./manastormShellRuntimeBridge";
 import {
   activateOnlineSession,
   hydrateOnlineSession,
+  isOnlineAuthenticationError,
   logoutOnlineSession,
   refreshOnlineSession,
 } from "./onlineAccountClient";
@@ -642,15 +643,17 @@ export function selectedCharacter(state: ShellState): CharacterProfile | null {
   return state.characters.find((character) => character.id === state.selectedCharacterId) ?? null;
 }
 
-if (restored.session?.accessToken) {
-  activateOnlineSession(restored.session);
-  void Promise.all([
-    hydrateOnlineSession(restored.session),
-    refreshOnlineSession(restored.session),
-  ]).then(([characters, refreshedSession]) => {
-    const current = useShellStore.getState().session;
-    if (current?.ownerId !== restored.session?.ownerId) return;
+const restoredOnlineSession = restored.session?.accessToken ? restored.session : null;
+if (restoredOnlineSession) {
+  activateOnlineSession(restoredOnlineSession);
+  void (async () => {
+    const refreshedSession = await refreshOnlineSession(restoredOnlineSession);
+    if (useShellStore.getState().session?.accessToken !== restoredOnlineSession.accessToken) return;
     saveSession(refreshedSession);
+    useShellStore.setState({ session: refreshedSession });
+    const characters = await hydrateOnlineSession(refreshedSession);
+    const current = useShellStore.getState().session;
+    if (current?.accessToken !== restoredOnlineSession.accessToken) return;
     useShellStore.setState({
       session: refreshedSession,
       characters,
@@ -660,7 +663,22 @@ if (restored.session?.accessToken) {
         : characters[0]?.id ?? null,
       notice: "Cloud roster synchronized.",
     });
-  }).catch((error) => {
+  })().catch((error) => {
+    if (useShellStore.getState().session?.accessToken !== restoredOnlineSession.accessToken) return;
+    if (isOnlineAuthenticationError(error)) {
+      clearSession();
+      activateOnlineSession(null);
+      useShellStore.setState({
+        phase: "login",
+        session: null,
+        characters: [],
+        bossCards: emptyBossCardCollection(),
+        selectedCharacterId: null,
+        activeCharacter: null,
+        notice: "Your session has expired. Please sign in again.",
+      });
+      return;
+    }
     useShellStore.setState({
       notice: error instanceof Error
         ? `${error.message} Using the cached roster.`