fix: reset-state-on-new-session-click

src/hooks/useProjectsState.ts

@@ -261,6 +261,27 @@ export function useProjectsState({
   const [showSettings, setShowSettings] = useState(false);
   const [settingsInitialTab, setSettingsInitialTab] = useState('agents');
   const [externalMessageUpdate, setExternalMessageUpdate] = useState(0);
+  /**
+   * `newSessionTrigger` is an explicit, monotonic intent signal for user-driven
+   * New Session actions.
+   *
+   * It exists because `handleNewSession` can be invoked while the app is already in
+   * the same visible state (`selectedSession === null`, `activeTab === 'chat'`,
+   * route already `/`). In that case, React/router updates are idempotent and no
+   * downstream reset logic runs.
+   *
+   * Usage across the codebase:
+   * 1) Produced here in `handleNewSession` via increment (always changes).
+   * 2) Returned from this hook and threaded through:
+   *    useProjectsState -> AppContent -> MainContent -> ChatInterface.
+   * 3) Consumed in `useChatSessionState` as an effect dependency to forcibly clear
+   *    chat-local state (`currentSessionId`, pending draft message, streaming flags,
+   *    pending session storage keys, pagination/scroll artifacts).
+   *
+   * Keeping this signal dedicated avoids coupling resets to unrelated counters/events
+   * (for example websocket/project refresh updates) that could cause accidental resets.
+   */
+  const [newSessionTrigger, setNewSessionTrigger] = useState(0);
 
   const loadingProgressTimeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null);
   const lastHandledMessageRef = useRef<AppSocketMessage | null>(null);
@@ -587,6 +608,7 @@ export function useProjectsState({
       setSelectedProject(project);
       setSelectedSession(null);
       setActiveTab('chat');
+      setNewSessionTrigger((previous) => previous + 1);
       navigate('/');
 
       if (isMobile) {
@@ -806,6 +828,7 @@ export function useProjectsState({
     showSettings,
     settingsInitialTab,
     externalMessageUpdate,
+    newSessionTrigger,
     setActiveTab,
     setSidebarOpen,
     setIsInputFocused,