fix(auth): reject load() when persist read fails

clients/web/src/App.tsx

@@ -2191,7 +2191,15 @@ function App() {
     }
 
     void (async () => {
-      await webOAuthStorage.load();
+      try {
+        await webOAuthStorage.load();
+      } catch (err) {
+        connectStartRef.current = undefined;
+        queueMicrotask(() => {
+          showReAuthBanner(server.id, err instanceof Error ? err : String(err));
+        });
+        return;
+      }
       const client = setupClientForServer(server, sessionId);
       setActiveServerId(server.id);
       try {

clients/web/src/test/core/auth/storage-remote.test.ts

@@ -1,5 +1,9 @@
 import { describe, it, expect, beforeEach, vi } from "vitest";
 import { RemoteOAuthStorage } from "@inspector/core/auth/remote/storage-remote.js";
+import {
+  type OAuthStore,
+  waitForOAuthStorePersistLoad,
+} from "@inspector/core/auth/store.js";
 
 const NOOP_FETCH = vi.fn(
   async () =>
@@ -121,6 +125,12 @@ describe("RemoteOAuthStorage (unit, mocked fetch)", () => {
     expect(s).toBeInstanceOf(RemoteOAuthStorage);
   });
 
+  it("waitForOAuthStorePersistLoad resolves for an unregistered store handle", async () => {
+    await expect(
+      waitForOAuthStorePersistLoad({} as OAuthStore),
+    ).resolves.toBeUndefined();
+  });
+
   it("load() waits for remote GET before sync reads see persisted state", async () => {
     const persisted = {
       state: {
@@ -155,4 +165,20 @@ describe("RemoteOAuthStorage (unit, mocked fetch)", () => {
       "persisted-verifier",
     );
   });
+
+  it("load() rejects when remote GET fails instead of hanging", async () => {
+    const failingFetch = vi.fn(
+      async () => new Response("server error", { status: 500 }),
+    ) as unknown as typeof fetch;
+
+    const failingStorage = new RemoteOAuthStorage({
+      baseUrl: "http://remote.example",
+      storeId: `fail-${Math.random().toString(36).slice(2)}`,
+      fetchFn: failingFetch,
+    });
+
+    await expect(failingStorage.load()).rejects.toThrow(
+      "Failed to read store: 500",
+    );
+  });
 });

core/auth/oauth-storage.ts

@@ -8,7 +8,11 @@ import {
   OAuthTokensSchema,
 } from "@modelcontextprotocol/sdk/shared/auth.js";
 import type { OAuthStorage } from "./storage.js";
-import { type createOAuthStore, type ServerOAuthState } from "./store.js";
+import {
+  type OAuthStore,
+  type ServerOAuthState,
+  waitForOAuthStorePersistLoad,
+} from "./store.js";
 import type {
   IdpSessionState,
   OAuthClientRegistrationKind,
@@ -16,10 +20,9 @@ import type {
   SaveTokensOptions,
 } from "./storage.js";
 
-type OAuthStoreWithPersist = ReturnType<typeof createOAuthStore> & {
+type OAuthStoreWithPersist = OAuthStore & {
   persist: {
     hasHydrated: () => boolean;
-    onFinishHydration: (fn: () => void) => void;
   };
 };
 
@@ -32,19 +35,18 @@ export class OAuthStorageBase implements OAuthStorage {
   private readonly store: OAuthStoreWithPersist;
   private loadedPromise: Promise<void> | undefined;
 
-  constructor(store: ReturnType<typeof createOAuthStore>) {
+  constructor(store: OAuthStore) {
     this.store = store as OAuthStoreWithPersist;
   }
 
   load(): Promise<void> {
     if (!this.loadedPromise) {
-      this.loadedPromise = new Promise((resolve) => {
+      this.loadedPromise = (async () => {
         if (this.store.persist.hasHydrated()) {
-          resolve();
           return;
         }
-        this.store.persist.onFinishHydration(() => resolve());
+        await waitForOAuthStorePersistLoad(this.store);
-      });
+      })();
     }
     return this.loadedPromise;
   }

core/auth/store.ts

@@ -43,6 +43,23 @@ export interface OAuthStoreState {
   clearEnterpriseManagedResourceServers: () => void;
 }
 
+export type OAuthStore = ReturnType<typeof createOAuthStore>;
+
+const persistLoadByStore = new WeakMap<OAuthStore, Promise<void>>();
+
+/**
+ * Wait until the store's initial persist read has finished (success or failure).
+ * Used by {@link OAuthStorageBase.load}; resolves on success, rejects when the
+ * storage adapter's getItem fails (Zustand does not fire onFinishHydration on error).
+ */
+export function waitForOAuthStorePersistLoad(store: OAuthStore): Promise<void> {
+  const promise = persistLoadByStore.get(store);
+  if (!promise) {
+    return Promise.resolve();
+  }
+  return promise;
+}
+
 /**
  * Creates a Zustand store for OAuth state with the given storage adapter.
  * The storage adapter handles persistence (file, remote HTTP, sessionStorage, etc.).
@@ -53,7 +70,29 @@ export interface OAuthStoreState {
 export function createOAuthStore(
   storage: ReturnType<typeof createJSONStorage>,
 ) {
-  return createStore<OAuthStoreState>()(
+  let resolvePersistLoad!: () => void;
+  let rejectPersistLoad!: (error: unknown) => void;
+  let persistLoadSettled = false;
+
+  const persistLoadPromise = new Promise<void>((resolve, reject) => {
+    resolvePersistLoad = resolve;
+    rejectPersistLoad = reject;
+  });
+
+  const settlePersistLoad = (error?: unknown) => {
+    if (persistLoadSettled) {
+      /* v8 ignore next -- idempotent if persist signals completion more than once */
+      return;
+    }
+    persistLoadSettled = true;
+    if (error) {
+      rejectPersistLoad(error);
+      return;
+    }
+    resolvePersistLoad();
+  };
+
+  const store = createStore<OAuthStoreState>()(
     persist(
       (set, get) => ({
         servers: {},
@@ -118,7 +157,13 @@ export function createOAuthStore(
       {
         name: "mcp-inspector-oauth",
         storage,
+        onRehydrateStorage: () => (_state, error) => {
+          settlePersistLoad(error);
+        },
       },
     ),
   );
+
+  persistLoadByStore.set(store, persistLoadPromise);
+  return store;
 }