feat(ui): show YouTube-confirmed live state in top bar

Normal ON-AIR stays red until YouTube reports lifeCycleStatus=live, then turns green; TEST stays gold and stop restores the idle color.

Status-color reference: https://www.carbondesignsystem.com/building-blocks/core/patterns/status-indicators

ViewModels/MainViewModel.Streaming.Operations.cs

@@ -234,6 +234,12 @@ public partial class MainViewModel : ViewModelBase
         EditingActive = false;
         await _framePump.StartAsync(); // never throws; failures log + surface via Failed
 
+        // Check promptly until YouTube confirms the broadcast is live. Health
+        // polling returns to its normal interval after that confirmation.
+        _healthPollTimer.Interval = TimeSpan.FromSeconds(2);
+        _healthPollTimer.Start();
+        _ = PollHealthAsync();
+
         string? liveChatId = null;
         try
         {
@@ -264,10 +270,6 @@ public partial class MainViewModel : ViewModelBase
             AppLog.Write($"Test session dock open for {_currentBroadcastId}");
         }
 
-        // Health polling (TASK 5 item 3): poll immediately, then every 30s while
-        // live. Report-by-exception — a banner appears only on warning/error.
-        _healthPollTimer.Start();
-        _ = PollHealthAsync();
     }
 
     private void OnHealthPollTick(object? sender, EventArgs e) => _ = PollHealthAsync();
@@ -293,19 +295,21 @@ public partial class MainViewModel : ViewModelBase
             {
                 AppLog.Write("Stream health poll failed; check the OAuth session",
                     AppLogMessageType.Error, AppLogErrorClass.Class2);
-                return;
             }
-            CurrentHealth.HealthStatus = health.HealthStatus;
-            CurrentHealth.HealthMessage = health.HealthStatus;
-            CurrentHealth.ConfigurationIssues.Clear();
-            CurrentHealth.ConfigurationIssues.AddRange(health.ConfigurationIssues);
-            OnPropertyChanged(nameof(CurrentHealth));
-            ApplyHealthIssue(health.ConfigurationIssues);
+            else
+            {
+                CurrentHealth.HealthStatus = health.HealthStatus;
+                CurrentHealth.HealthMessage = health.HealthStatus;
+                CurrentHealth.ConfigurationIssues.Clear();
+                CurrentHealth.ConfigurationIssues.AddRange(health.ConfigurationIssues);
+                OnPropertyChanged(nameof(CurrentHealth));
+                ApplyHealthIssue(health.ConfigurationIssues);
+            }
 
             if (!string.IsNullOrWhiteSpace(_currentBroadcastId) && !_broadcastSeenLive)
             {
                 var lifeCycle = await _youtubeStream.LogBroadcastDiagnosticsAsync(_currentBroadcastId, _reusableStream.Id);
-                if (lifeCycle is "live" or "liveStarting") _broadcastSeenLive = true;
+                ApplyBroadcastLifecycleStatus(lifeCycle);
             }
         }
         catch (Exception ex)
@@ -505,17 +509,23 @@ public partial class MainViewModel : ViewModelBase
     private void UpdateLiveVisuals()
     {
         var live = IsLive;
-        // A live TEST broadcast wears gold, not the live red — the TEST badge +
-        // gold are the "this is a rehearsal" cue (TASK 41).
+        // TEST keeps its gold identity. For a normal ON-AIR session, green means
+        // YouTube has confirmed live; before then it keeps the existing red color.
         TopBarBackground = live
-            ? ThemeBrush.Hex(IsTestStream ? "Brush.TestContainer" : "Brush.Primary")
+            ? IsTestStream
+                ? ThemeBrush.Hex("Brush.TestContainer")
+                : ThemeBrush.Hex(_youtubeBroadcastLive ? "Brush.Positive" : "Brush.Primary")
             : ThemeBrush.Hex("Brush.SurfaceContainer");
         PreviewGlowBrush = live
             ? ThemeBrush.Hex(IsTestStream ? "Brush.TestContainer" : "Brush.Primary")
             : "Transparent";
         PreviewGlowThickness = live ? new Thickness(3) : new Thickness(0);
 
-        if (!live) _healthPollTimer.Stop();
+        if (!live)
+        {
+            _healthPollTimer.Stop();
+            _healthPollTimer.Interval = TimeSpan.FromSeconds(30);
+        }
 
         // NOTE: the branding credit is deliberately NOT started/stopped here.
         // CREATOR RULING 2026-09-26 — it must appear in EVERY scene and in

ViewModels/MainViewModel.Streaming.cs

@@ -24,6 +24,7 @@ public partial class MainViewModel : ViewModelBase
     /// <summary>Latches once the broadcast reaches live so the per-poll broadcast
     /// diagnostic stops logging (2026-10-04). Reset at broadcast creation.</summary>
     private bool _broadcastSeenLive;
+    private bool _youtubeBroadcastLive;
     private string? _reusableStreamUrl;
     private ReusableStream? _reusableStream;
     private string? _healthIssueBanner;
@@ -63,6 +64,7 @@ public partial class MainViewModel : ViewModelBase
         {
             if (SetProperty(ref _streamStatus, value))
             {
+                _youtubeBroadcastLive = false;
                 OnPropertyChanged(nameof(IsOffline));
                 OnPropertyChanged(nameof(IsLive));
                 OnPropertyChanged(nameof(IsEditMode));
@@ -373,6 +375,22 @@ public partial class MainViewModel : ViewModelBase
         set => SetProperty(ref _topBarBackground, value);
     }
 
+    internal void ApplyBroadcastLifecycleStatus(string? lifeCycleStatus)
+    {
+        if (!IsLive) return;
+        if (!string.Equals(lifeCycleStatus, "live", StringComparison.OrdinalIgnoreCase))
+        {
+            if (!_broadcastSeenLive)
+                _healthPollTimer.Interval = TimeSpan.FromSeconds(2);
+            return;
+        }
+
+        _broadcastSeenLive = true;
+        _youtubeBroadcastLive = true;
+        _healthPollTimer.Interval = TimeSpan.FromSeconds(30);
+        UpdateLiveVisuals();
+    }
+
     public string PreviewGlowBrush
     {
         get => _previewGlowBrush;