fix: persist OIDC token in localStorage instead of sessionStorage

Bug: opening calendar in a new browser tab forced a re-login every time,
even when the user was authenticated in another tab.

Root cause: tokenSet/userData/redirectState were stored in sessionStorage,
which is per-tab by design. New tab → empty sessionStorage → app
redirects to OIDC. With Dex's password-DB connector (no IdP-side session
cookie), Dex re-prompts for credentials.

Mail (tmail-flutter) has the same OIDC flow but persists tokens in
IndexedDB (Hive box `tokenoidccache`) which IS shared across tabs —
hence mail SSO worked but calendar didn't.

Fix: replace sessionStorage with localStorage for the auth-related keys
(tokenSet, userData, redirectState). localStorage is shared across tabs
of the same origin. Other sessionStorage usages (e.g. eventUpdateModalReopen)
are unchanged — they are genuinely per-tab.

Files touched:
- src/features/User/useInitializeApp.ts (load + setup redirect state)
- src/features/User/LoginCallback.tsx (save tokens after callback,
  read pending redirectState, removeItem on completion)
- src/utils/apiUtils.ts (write redirectState during 401-driven SSO redirect)
- src/components/Calendar/hooks/useUtilMenus.ts (logout cleanup)

Verified: open clean tab → login alice → open another tab on
calendar.workavia.local → loaded silently with avatar visible, no
login form prompted.

src/components/Calendar/hooks/useUtilMenus.ts

@@ -58,7 +58,7 @@ export const useUtilMenus = (): {
     } catch (error) {
       console.error('Logout failed:', error)
     } finally {
-      sessionStorage.removeItem('tokenSet')
+      localStorage.removeItem('tokenSet')
       handleUserMenuClose()
     }
   }

src/features/User/LoginCallback.tsx

@@ -27,26 +27,26 @@ export function CallbackResume() {
 
     const runCallback = async () => {
       // Read redirectState inside useEffect to avoid stale closures
-      const saved = sessionStorage.getItem('redirectState')
-        ? JSON.parse(sessionStorage.getItem('redirectState') ?? '{}')
+      const saved = localStorage.getItem('redirectState')
+        ? JSON.parse(localStorage.getItem('redirectState') ?? '{}')
         : null
 
       // Check if we have saved tokens (already logged in)
-      const savedToken = sessionStorage.getItem('tokenSet')
-        ? JSON.parse(sessionStorage.getItem('tokenSet') ?? '{}')
+      const savedToken = localStorage.getItem('tokenSet')
+        ? JSON.parse(localStorage.getItem('tokenSet') ?? '{}')
         : null
 
       // If no redirectState but we have saved session, just go home
       // This can happen if user refreshes callback page or gets redirected here after already logged in
       if (!saved?.code_verifier) {
         if (savedToken) {
-          sessionStorage.removeItem('redirectState')
+          localStorage.removeItem('redirectState')
           dispatch(replace('/'))
           return
         }
 
         console.warn('Missing redirectState')
-        sessionStorage.removeItem('redirectState')
+        localStorage.removeItem('redirectState')
         dispatch(replace('/'))
         return
       }
@@ -60,10 +60,14 @@ export function CallbackResume() {
           throw new Error('OAuth callback failed')
         }
 
-        // IMPORTANT: Save tokens to sessionStorage FIRST before making any API calls
-        // because API calls will read token from sessionStorage
-        sessionStorage.setItem('tokenSet', JSON.stringify(data.tokenSet))
-        sessionStorage.setItem('userData', JSON.stringify(data.userinfo))
+        // IMPORTANT: Save tokens to localStorage FIRST before making any API calls
+        // because API calls will read token from localStorage.
+        // localStorage (not sessionStorage) so the OIDC session is shared
+        // across browser tabs — otherwise each new tab forces a re-login
+        // since Dex (with enablePasswordDB connector) does NOT keep an
+        // IdP-side session cookie.
+        localStorage.setItem('tokenSet', JSON.stringify(data.tokenSet))
+        localStorage.setItem('userData', JSON.stringify(data.userinfo))
 
         dispatch(setUserData(data.userinfo))
         dispatch(setTokens(data.tokenSet))
@@ -71,7 +75,7 @@ export function CallbackResume() {
         await dispatch(getOpenPaasUserDataAsync())
         await dispatch(getCalendarsListAsync())
 
-        sessionStorage.removeItem('redirectState')
+        localStorage.removeItem('redirectState')
       } catch (e) {
         console.error('OIDC callback error:', e)
         dispatch(setAppLoading(false))

src/features/User/useInitializeApp.ts

@@ -23,11 +23,11 @@ export function useInitializeApp() {
     hasInitiatedRef.current = true
 
     const initiateLogin = async () => {
-      const savedToken = sessionStorage.getItem('tokenSet')
-        ? JSON.parse(sessionStorage.getItem('tokenSet') ?? '{}')
+      const savedToken = localStorage.getItem('tokenSet')
+        ? JSON.parse(localStorage.getItem('tokenSet') ?? '{}')
         : null
-      const savedUser = sessionStorage.getItem('userData')
-        ? JSON.parse(sessionStorage.getItem('userData') ?? '{}')
+      const savedUser = localStorage.getItem('userData')
+        ? JSON.parse(localStorage.getItem('userData') ?? '{}')
         : null
 
       if (savedToken && savedUser) {
@@ -45,7 +45,7 @@ export function useInitializeApp() {
       }
 
       const loginurl = await Auth()
-      sessionStorage.setItem(
+      localStorage.setItem(
         'redirectState',
         JSON.stringify({
           code_verifier: loginurl.code_verifier,

src/utils/apiUtils.ts

@@ -35,7 +35,7 @@ const redirectSSO = async (
   try {
     const loginurl = await Auth()
 
-    sessionStorage.setItem(
+    localStorage.setItem(
       'redirectState',
       JSON.stringify({
         code_verifier: loginurl.code_verifier,
@@ -85,9 +85,9 @@ export const api: KyInstance = ky.extend({
   hooks: {
     beforeRequest: [
       async (request: KyRequest): Promise<KyRequest> => {
-        const saved = sessionStorage.getItem('tokenSet')
+        const saved = localStorage.getItem('tokenSet')
           ? (JSON.parse(
-              sessionStorage.getItem('tokenSet') ?? '{}'
+              localStorage.getItem('tokenSet') ?? '{}'
             ) as TokenEndpointResponse & TokenEndpointResponseHelpers)
           : null
         const access_token = saved?.access_token as string