fix: clean up stale file tree paths on startup

Removes missing expanded folders from persisted Files state
Prevents repeated 404 noise for stale file tree paths
Avoids startup SDK race when restoring sessions

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

@@ -220,6 +220,21 @@ function createChildStores(entries: Array<[string, StoreApi<DirectoryStore>]>) {
   } as unknown as import("./child-store").ChildStoreManager
 }
 
+describe("fetchMessagesForSession startup race", () => {
+  test("does not reject before sync action refs are initialized", async () => {
+    const { fetchMessagesForSession } = await import("./session-actions")
+
+    let error: unknown = null
+    try {
+      await fetchMessagesForSession("session-a", "/test/project")
+    } catch (err) {
+      error = err
+    }
+
+    expect(error).toBe(null)
+  })
+})
+
 describe("shareSession live state", () => {
   beforeEach(() => {
     replyCalls.length = 0

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

@@ -1126,19 +1126,19 @@ export async function fetchMessagesForSession(sessionID: string, directory?: str
   const resolvedDir = directory ?? dir()
   if (!resolvedDir) return
 
-  const s = sdk()
-  const store = directory
-    ? dirStoreForDirectory(directory)
-    : dirStore()
-
-  if (getSessionMaterializationStatus(store.getState(), sessionID).renderable) return
-
   const loadingKey = `${resolvedDir}:${sessionID}`
   if (FETCH_MESSAGES_LOADING.has(loadingKey)) return
 
   FETCH_MESSAGES_LOADING.add(loadingKey)
 
   try {
+    const s = sdk()
+    const store = directory
+      ? dirStoreForDirectory(directory)
+      : dirStore()
+
+    if (getSessionMaterializationStatus(store.getState(), sessionID).renderable) return
+
     const result = await retry(async () => {
       const response = await s.session.messages({
         sessionID,