Fix incremental thread event UI state seeding and remove redundant useShallow

- Call syncThreads in applyEventBatch for thread.created/thread.deleted events
  so incrementally created threads get their seedVisitedAt populated in
  threadLastVisitedAtById, matching the snapshot recovery path behavior.

- Remove unnecessary useShallow wrapper from store.projects and store.threads
  selectors in Sidebar. Zustand's default Object.is comparison already skips
  re-renders when these array references are unchanged, making the O(n)
  shallow comparison pure overhead.

Author: cursoragent

apps/web/src/components/Sidebar.tsx

@@ -436,8 +436,8 @@ function SortableProjectItem({
 }
 
 export default function Sidebar() {
-  const projects = useStore(useShallow((store) => store.projects));
-  const serverThreads = useStore(useShallow((store) => store.threads));
+  const projects = useStore((store) => store.projects);
+  const serverThreads = useStore((store) => store.threads);
   const { projectExpandedById, projectOrder, threadLastVisitedAtById } = useUiStateStore(
     useShallow((store) => ({
       projectExpandedById: store.projectExpandedById,

apps/web/src/routes/__root.tsx

@@ -230,6 +230,18 @@ function EventRouter() {
         const projects = useStore.getState().projects;
         syncProjects(projects.map((project) => ({ id: project.id, cwd: project.cwd })));
       }
+      const needsThreadUiSync = nextEvents.some(
+        (event) => event.type === "thread.created" || event.type === "thread.deleted",
+      );
+      if (needsThreadUiSync) {
+        const threads = useStore.getState().threads;
+        syncThreads(
+          threads.map((thread) => ({
+            id: thread.id,
+            seedVisitedAt: thread.updatedAt ?? thread.createdAt,
+          })),
+        );
+      }
       const draftStore = useComposerDraftStore.getState();
       for (const threadId of batchEffects.clearPromotedDraftThreadIds) {
         clearPromotedDraftThread(threadId);