Prevent restored file trees from crashing desktop startup (#2595)

* fix(explorer): prevent persisted trees from crashing startup

Persisted expansion restored every directory and recursively flattened the resulting tree during render. Limit automatic restoration to five rendered directory levels and flatten iteratively so deep or broad workspaces cannot exhaust the JavaScript stack.

* fix(explorer): preserve expansion changes during restore

Reconcile completed restoration against the current expansion set atomically so folder interactions made while directory requests are in flight are not overwritten.

* fix(explorer): show hidden files before restoration

* fix(explorer): apply directory toggles atomically

packages/app/src/hooks/use-file-explorer-actions.ts

@@ -1,6 +1,10 @@
 import { useCallback, useMemo } from "react";
 import { useTranslation } from "react-i18next";
-import { useSessionStore, type AgentFileExplorerState } from "@/stores/session-store";
+import {
+  useSessionStore,
+  type AgentFileExplorerState,
+  type ExplorerDirectory,
+} from "@/stores/session-store";
 import { explorerFileFromReadResult } from "@/file-explorer/read-result";
 
 function createExplorerState(): AgentFileExplorerState {
@@ -88,9 +92,9 @@ export function useFileExplorerActions(params: { serverId: string } & FileExplor
     async (
       path: string,
       options?: { recordHistory?: boolean; setCurrentPath?: boolean },
-    ): Promise<boolean> => {
+    ): Promise<ExplorerDirectory | null> => {
       if (!workspaceStateKey) {
-        return false;
+        return null;
       }
       const normalizedPath = path && path.length > 0 ? path : ".";
       const shouldSetCurrentPath = options?.setCurrentPath ?? true;
@@ -119,7 +123,7 @@ export function useFileExplorerActions(params: { serverId: string } & FileExplor
           lastError: t("workspace.fileExplorer.states.unavailable"),
           pendingRequest: null,
         }));
-        return false;
+        return null;
       }
 
       if (!client) {
@@ -129,7 +133,7 @@ export function useFileExplorerActions(params: { serverId: string } & FileExplor
           lastError: t("workspace.terminal.hostDisconnected"),
           pendingRequest: null,
         }));
-        return false;
+        return null;
       }
 
       try {
@@ -150,7 +154,7 @@ export function useFileExplorerActions(params: { serverId: string } & FileExplor
 
           return nextState;
         });
-        return true;
+        return directory;
       } catch (error) {
         updateExplorerState((state) => ({
           ...state,
@@ -161,7 +165,7 @@ export function useFileExplorerActions(params: { serverId: string } & FileExplor
               : t("workspace.fileExplorer.errors.failedToListDirectory"),
           pendingRequest: null,
         }));
-        return false;
+        return null;
       }
     },
     [client, normalizedWorkspaceRoot, t, updateExplorerState, workspaceStateKey],