fix: prevent admin page redirect during token refresh

adminFetch called logout() directly on 401/403 responses, which cleared
roles and caused RequireAdmin to redirect to /exchanges while users were
editing forms. Now adminFetch attempts a token refresh before failing,
and RequireAdmin tolerates a transient empty-roles state during refresh.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/api/queries/admin/admin-api.ts

@@ -1,9 +1,40 @@
 import { config } from '../../../config';
 import { useAuthStore } from '../../../auth/auth-store';
 
+/**
+ * Shared fetch helper for admin API endpoints.
+ *
+ * On a 401 response the helper attempts a single token refresh and retries
+ * the original request.  Only if the retry also fails (or there is no refresh
+ * token) does it fall through to the normal error path.
+ *
+ * Previously this function called `logout()` directly on 401/403 which could
+ * race with background polling: when an access-token expired while the user
+ * was editing a form, the immediate logout cleared `roles`, causing
+ * `RequireAdmin` to redirect to `/` -> `/exchanges` and losing unsaved state.
+ */
 export async function adminFetch<T>(path: string, options?: RequestInit): Promise<T> {
+  const res = await _doFetch(path, options);
+
+  // 401 — attempt a token refresh and retry once
+  if (res.status === 401) {
+    const refreshed = await useAuthStore.getState().refresh();
+    if (refreshed) {
+      const retry = await _doFetch(path, options);
+      return _handleResponse<T>(retry);
+    }
+    // Refresh failed — throw without calling logout().
+    // The central onUnauthorized handler (use-auth.ts) will take care of
+    // redirecting to /login if appropriate.
+    throw new Error('Unauthorized');
+  }
+
+  return _handleResponse<T>(res);
+}
+
+async function _doFetch(path: string, options?: RequestInit): Promise<Response> {
   const token = useAuthStore.getState().accessToken;
-  const res = await fetch(`${config.apiBaseUrl}/admin${path}`, {
+  return fetch(`${config.apiBaseUrl}/admin${path}`, {
     ...options,
     headers: {
       'Content-Type': 'application/json',
@@ -12,8 +43,10 @@ export async function adminFetch<T>(path: string, options?: RequestInit): Promis
       ...options?.headers,
     },
   });
+}
+
+async function _handleResponse<T>(res: Response): Promise<T> {
   if (res.status === 401 || res.status === 403) {
-    useAuthStore.getState().logout();
     throw new Error('Unauthorized');
   }
   if (!res.ok) {