backend old version request

src/app/pages/fastcheck-page/fastcheck-page.html

@@ -25,10 +25,11 @@
             type="text"
             class="input"
             [ngModel]="fastcheckNumber()"
-            (ngModelChange)="fastcheckNumber.set($event)"
+            (ngModelChange)="onNumberChange($event)"
             placeholder="1234-5678-0001"
             inputmode="numeric"
             autocomplete="off"
+            maxlength="14"
           />
           <a class="btn btn--ghost" routerLink="/new" aria-label="Создать новый fastCHECK">Новый</a>
         </div>
@@ -49,8 +50,12 @@
             step="1"
             inputmode="numeric"
             placeholder="0"
+            [readonly]="amountLoading() || fastcheckAmount() !== null"
           />
         </div>
+        @if (amountLoading()) {
+          <span class="field__hint">Проверяем…</span>
+        }
       </div>
 
       <!-- Code -->
@@ -61,10 +66,10 @@
           type="text"
           class="input"
           [ngModel]="fastcheckCode()"
-          (ngModelChange)="fastcheckCode.set($event)"
-          placeholder="0000"
+          (ngModelChange)="onCodeChange($event)"
+          placeholder="00000"
           inputmode="numeric"
-          maxlength="8"
+          maxlength="5"
           autocomplete="one-time-code"
         />
         @if (error()) {
@@ -72,7 +77,7 @@
         }
       </div>
 
-      <button class="pay-btn" type="button" (click)="pay()">
+      <button class="pay-btn" type="button" (click)="pay()" [disabled]="!canPay()">
         <span class="pay-btn__icon">
           <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor"
                stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round">