fix: Demo navigation via history API and route sync.

Replace unreliable pathname assignment with pushState and central route syncing so the demo opens from the login screen and responds to browser back/forward.

Co-authored-by: Cursor <cursoragent@cursor.com>

client/src/App.tsx

@@ -1,4 +1,4 @@
-import { useState, useEffect } from 'react'
+import { useState, useEffect, useCallback } from 'react'
 import './App.css'
 import { DialogProvider } from './components/ModalDialog.tsx'
 import AuthOnboarding from './components/AuthOnboarding.tsx'
@@ -59,7 +59,7 @@ function App() {
   const [shareKey, setShareKey] = useState('')
 
   // Public demo mode (no account required)
-  const [isDemoMode, setIsDemoMode] = useState(false)
+  const [isDemoMode, setIsDemoMode] = useState(() => window.location.pathname === '/demo')
 
   const syncQueueCount = useLiveQuery(
     () => activeLogbookId ? db.syncQueue.where({ logbookId: activeLogbookId }).count() : db.syncQueue.count(),
@@ -138,26 +138,37 @@ function App() {
     }
   }, [isAuthenticated])
 
-  useEffect(() => {
+  const syncRouteFromLocation = useCallback(() => {
     const params = new URLSearchParams(window.location.search)
     const hashParams = new URLSearchParams(window.location.hash.substring(1))
+    const path = window.location.pathname
 
-    if (window.location.pathname === '/demo') {
+    if (path === '/demo') {
       setIsDemoMode(true)
+      setIsViewerMode(false)
+      setIsAcceptingInvite(false)
       return
     }
 
-    if (window.location.pathname === '/share' && params.has('token') && hashParams.has('key')) {
+    setIsDemoMode(false)
+
+    if (path === '/share' && params.has('token') && hashParams.has('key')) {
       setShareToken(params.get('token') || '')
       setShareKey(hashParams.get('key') || '')
       setIsViewerMode(true)
+      setIsAcceptingInvite(false)
       return
     }
 
+    setIsViewerMode(false)
+
     if (params.has('token')) {
       setIsAcceptingInvite(true)
+      return
     }
 
+    setIsAcceptingInvite(false)
+
     const savedUser = localStorage.getItem('active_username')
     const key = getActiveMasterKey()
     if (savedUser && key) {
@@ -171,6 +182,19 @@ function App() {
     }
   }, [])
 
+  useEffect(() => {
+    syncRouteFromLocation()
+    window.addEventListener('popstate', syncRouteFromLocation)
+    return () => window.removeEventListener('popstate', syncRouteFromLocation)
+  }, [syncRouteFromLocation])
+
+  const openDemo = useCallback(() => {
+    window.history.pushState({}, document.title, '/demo')
+    setIsDemoMode(true)
+    setIsViewerMode(false)
+    setIsAcceptingInvite(false)
+  }, [])
+
   useEffect(() => {
     registerNavigation({
       setActiveTab,
@@ -245,7 +269,7 @@ function App() {
 
   const handleExitDemo = () => {
     window.history.replaceState({}, document.title, '/')
-    setIsDemoMode(false)
+    syncRouteFromLocation()
   }
 
   if (isDemoMode) {
@@ -288,7 +312,7 @@ function App() {
   if (!isAuthenticated) {
     return (
       <div className="auth-screen">
-        <AuthOnboarding onAuthenticated={handleAuthenticated} />
+        <AuthOnboarding onAuthenticated={handleAuthenticated} onOpenDemo={openDemo} />
       </div>
     )
   }

client/src/components/AuthOnboarding.tsx

@@ -16,9 +16,10 @@ import RegistrationDisclaimer from './RegistrationDisclaimer.tsx'
 
 interface AuthOnboardingProps {
   onAuthenticated: () => void
+  onOpenDemo?: () => void
 }
 
-export default function AuthOnboarding({ onAuthenticated }: AuthOnboardingProps) {
+export default function AuthOnboarding({ onAuthenticated, onOpenDemo }: AuthOnboardingProps) {
   const { t, i18n } = useTranslation()
   const [username, setUsername] = useState('')
   const [loading, setLoading] = useState(false)
@@ -526,7 +527,7 @@ export default function AuthOnboarding({ onAuthenticated }: AuthOnboardingProps)
         <button
           type="button"
           className="btn secondary"
-          onClick={() => { window.location.pathname = '/demo' }}
+          onClick={() => onOpenDemo?.()}
           disabled={loading}
           style={{ width: '100%' }}
         >