Preserve registration form while rechecking access

frontend/src/app/register/page.tsx

@@ -307,7 +307,10 @@ export default function Register() {
     }
   };
 
-  if (registration.state !== "allowed") {
+  if (
+    registration.state !== "allowed" &&
+    !(registration.state === "loading" && registration.previouslyAllowed)
+  ) {
     return (
       <RegistrationAccessNotice
         state={registration.state}
@@ -355,6 +358,12 @@ export default function Register() {
             </div>
           )}
 
+          {registration.state === "loading" && (
+            <p className="app-text-muted mb-4 text-sm" role="status">
+              Проверяем доступность регистрации…
+            </p>
+          )}
+
           <form onSubmit={handleSubmit} className="space-y-6">
             {/* Шаг 1: Личные данные */}
             {currentStep === 1 && (
@@ -710,7 +719,7 @@ export default function Register() {
 
               <button
                 type="submit"
-                disabled={isLoading}
+                disabled={isLoading || registration.state !== "allowed"}
                 className="app-action-primary flex-1 rounded-lg px-4 py-3 text-sm font-semibold disabled:cursor-not-allowed disabled:opacity-50"
               >
                 {isLoading ? (

frontend/src/hooks/useRegistrationAvailability.ts

@@ -53,6 +53,7 @@ export function useRegistrationAvailability() {
       result?.generation === generation
         ? result.state
         : ("loading" as RegistrationAvailability),
+    previouslyAllowed: result?.state === "allowed",
     refresh,
   };
 }