fix(mobile): navigation back behavior, scroll button position

- New Chat → Chat uses replaceState so back skips new chat screen
- Active tab persisted to sessionStorage, restored on back navigation
- Scroll-to-bottom button positioned relative to footer (not hardcoded)
- overscroll-behavior: none to prevent iOS rubber-band

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/App.tsx

@@ -36,7 +36,7 @@ function persistView(view: View) {
   sessionStorage.setItem('currentView', JSON.stringify(view));
 }
 
-function navigateTo(view: View) {
+function navigateTo(view: View, replace = false) {
   persistView(view);
   let url = '/';
   if (view.name === 'chat' && view.sessionId) {
@@ -45,8 +45,12 @@ function navigateTo(view: View) {
   } else if (view.name === 'settings') {
     url = '/?view=settings';
   }
+  if (replace) {
+    window.history.replaceState({ view }, '', url);
+  } else {
     window.history.pushState({ view }, '', url);
   }
+}
 
 export function App() {
   const [authed, setAuthed] = useState(isAuthenticated());
@@ -225,7 +229,7 @@ export function App() {
     // Navigate to chat view with cwd — ChatView will pick up globals and send the prompt
     const chatCwd = view.name === 'newchat' ? view.cwd : undefined;
     const v: View = { name: 'chat', cwd: chatCwd, initialPrompt: options.prompt, adapter: options.adapter };
-    navigateTo(v);
+    navigateTo(v, true); // replace newchat → chat so back goes to session list
     setView(v);
   }, [view]);
 

src/components/ChatBody.tsx

@@ -253,16 +253,18 @@ export function ChatBody({
         )}
       </div>
 
-      {/* Scroll-to-bottom button */}
+      {/* Scroll-to-bottom button — sits just above the footer area */}
+      <div className="relative shrink-0">
         {userScrolled && (
           <button
             onClick={() => { setUserScrolled(false); scrollToBottom(true); }}
-          className="absolute bottom-20 right-4 w-8 h-8 rounded-full bg-surface border border-border flex items-center justify-center shadow-lg hover:bg-surface-light transition-colors z-10"
+            className="absolute -top-10 right-4 w-8 h-8 rounded-full bg-surface border border-border flex items-center justify-center shadow-lg hover:bg-surface-light transition-colors z-10"
             aria-label="Scroll to bottom"
           >
             <ArrowDownToLine className="w-4 h-4 text-text-secondary" />
           </button>
         )}
+      </div>
 
       {renderAboveInput?.()}
 

src/hooks/useSessions.ts

@@ -8,7 +8,14 @@ export function useSessions() {
     () => localStorage.getItem(STORAGE.PROJECT_DIR)
   );
   const [loading, setLoading] = useState(true);
-  const [activeTab, setActiveTab] = useState<'projects' | 'active'>('projects');
+  const [activeTab, _setActiveTab] = useState<'projects' | 'active'>(() => {
+    const stored = sessionStorage.getItem(STORAGE.SESSIONS_TAB);
+    return stored === 'active' ? 'active' : 'projects';
+  });
+  const setActiveTab = useCallback((tab: 'projects' | 'active') => {
+    _setActiveTab(tab);
+    sessionStorage.setItem(STORAGE.SESSIONS_TAB, tab);
+  }, []);
   const [activeSessions, setActiveSessions] = useState<any[]>([]);
 
   const fetchAll = useCallback(async () => {

src/lib/storage-keys.ts

@@ -5,6 +5,7 @@ export const STORAGE = {
   PROJECT_DIR: 'clawtap:projectDir',
   DRAFT: 'clawtap:draft',
   INSTALL_DISMISSED: 'clawtap:install-dismissed',
+  SESSIONS_TAB: 'clawtap:sessionsTab',
   adapterPrefs: (id: string) => `clawtap:adapterPrefs:${id}` as const,
 } as const;