fix: prevent mobile session resync flicker

Avoid unnecessary resync on clean initial stream connect
Skip no-op message snapshot writes during recovery
Only trigger mobile resume sync after real app resume

packages/ui/src/apps/MobileApp.tsx

@@ -202,19 +202,30 @@ const useNativeMobileChrome = (): void => {
 };
 
 const useNativeMobileLifecycle = (onResume: () => void): void => {
+  const wasInactiveRef = React.useRef(false);
+
   React.useEffect(() => {
     if (!isCapacitorMobileApp()) return;
 
     let disposed = false;
     const cleanup: Array<() => void> = [];
+    const resumeAfterInactive = () => {
+      if (!wasInactiveRef.current) return;
+      wasInactiveRef.current = false;
+      onResume();
+    };
 
     void import('@capacitor/app').then(async ({ App }) => {
       if (disposed) return;
       const state = await App.addListener('appStateChange', ({ isActive }) => {
         document.documentElement.classList.toggle('oc-native-app-active', isActive);
-        if (isActive) onResume();
+        if (!isActive) {
+          wasInactiveRef.current = true;
+          return;
+        }
+        resumeAfterInactive();
       });
-      const resume = await App.addListener('resume', onResume);
+      const resume = await App.addListener('resume', resumeAfterInactive);
       if (disposed) {
         void state.remove();
         void resume.remove();

packages/ui/src/sync/session-actions.ts

@@ -1169,6 +1169,10 @@ export async function fetchMessagesForSession(sessionID: string, directory?: str
     // can't repopulate (and un-evict) a session already navigated away from.
     if (useSessionUIStore.getState().currentSessionId !== sessionID) return
 
+    const latestState = store.getState()
+    const latestStatus = getSessionMaterializationStatus(latestState, sessionID)
+    if (latestStatus.renderable && (latestState.message[sessionID]?.length ?? 0) >= records.length) return
+
     store.setState((state) => {
       const materialized = materializeSessionSnapshots(
         state,
@@ -1179,6 +1183,7 @@ export async function fetchMessagesForSession(sessionID: string, directory?: str
         })),
         { skipPartTypes: MESSAGE_REFETCH_SKIP_PARTS },
       )
+      if (!materialized.messagesChanged && !materialized.partsChanged) return state
       return { message: materialized.message, part: materialized.part }
     })
   } catch {

packages/ui/src/sync/sync-context.tsx

@@ -286,6 +286,9 @@ async function materializeSessionFromServer(
       })),
       { skipPartTypes: RECONNECT_SKIP_PARTS },
     )
+    if (!materialized.messagesChanged && !materialized.partsChanged) {
+      return state
+    }
     return { message: materialized.message, part: materialized.part }
   })
 
@@ -1708,6 +1711,8 @@ export function SyncProvider(props: {
   const resyncingDirectoriesRef = useRef(new Set<string>())
   const statusPollingDirectoriesRef = useRef(new Set<string>())
   const pipelineReconnectRef = useRef<((reason?: string) => void) | null>(null)
+  const pipelineHasConnectedRef = useRef(false)
+  const pipelineDisconnectedBeforeFirstConnectRef = useRef(false)
 
   const system = useMemo<SyncSystem>(
     () => ({
@@ -1909,6 +1914,11 @@ export function SyncProvider(props: {
           hasEverConnected: true,
           connectionPhase: "connected",
         })
+        const isFirstConnect = !pipelineHasConnectedRef.current
+        pipelineHasConnectedRef.current = true
+        if (isFirstConnect && !pipelineDisconnectedBeforeFirstConnectRef.current) {
+          return
+        }
         if (isRecentBoot()) {
           return
         }
@@ -1917,6 +1927,9 @@ export function SyncProvider(props: {
         }
       },
       onDisconnect: (reason) => {
+        if (!pipelineHasConnectedRef.current) {
+          pipelineDisconnectedBeforeFirstConnectRef.current = true
+        }
         const { hasEverConnected } = useConfigStore.getState()
         useConfigStore.setState({
           isConnected: false,