fix: show extra usage credits from extra_usage fallback; preserve on refresh

windows/Models.cs

@@ -34,8 +34,10 @@ public class WindowData
 
 public class ExtraUsage
 {
-    [JsonPropertyName("is_enabled")] public bool    IsEnabled { get; set; }
+    [JsonPropertyName("is_enabled")]    public bool    IsEnabled    { get; set; }
-    [JsonPropertyName("currency")]   public string? Currency  { get; set; }
+    [JsonPropertyName("currency")]      public string? Currency     { get; set; }
+    [JsonPropertyName("used_credits")]  public double? UsedCredits  { get; set; }
+    [JsonPropertyName("monthly_limit")] public double? MonthlyLimit { get; set; }
 }
 
 public class BootstrapResponse

windows/PopupWindow.xaml.cs

@@ -247,9 +247,10 @@ public partial class PopupWindow : Window
         var prepaid  = VM.Prepaid;
         var currency = VM.ExtraUsage?.Currency ?? overage?.Currency ?? "$";
 
-        var spent   = overage?.UsedCredits         ?? 0;
+        // Fall back to extra_usage fields when the overage/prepaid endpoints return nothing
-        var limit   = overage?.MonthlyCreditLimit  ?? 0;
+        var spent   = overage?.UsedCredits        ?? VM.ExtraUsage?.UsedCredits  ?? 0;
-        var balance = prepaid?.Amount              ?? 0;
+        var limit   = overage?.MonthlyCreditLimit ?? VM.ExtraUsage?.MonthlyLimit ?? 0;
+        var balance = prepaid?.Amount             ?? 0;
 
         UIElement MakeRow(string label, string value)
         {

windows/UsageViewModel.cs

@@ -147,7 +147,15 @@ public class UsageViewModel : INotifyPropertyChanged
 
             await Application.Current.Dispatcher.InvokeAsync(() =>
             {
-                if (limits.Count > 0) { Limits = limits; Overage = overage; Prepaid = prepaid; ExtraUsage = extraUsage; }
+                if (limits.Count > 0)
+                {
+                    Limits    = limits;
+                    Overage   = overage;
+                    Prepaid   = prepaid;
+                    // Only clear ExtraUsage if the API explicitly disables it; keep cached value
+                    // if the HTTP endpoint omits the field (it often does for non-browser clients)
+                    if (extraUsage != null) ExtraUsage = extraUsage;
+                }
                 if (!string.IsNullOrEmpty(planLabel)) PlanLabel = planLabel;
                 if (!string.IsNullOrEmpty(email)) UserEmail = email;
                 IsSignedIn   = true;