Update chat tracking contexts after reattaching

Fixes #1490

src/Tgstation.Server.Host/Components/Chat/ChatManager.cs

@@ -232,7 +232,6 @@ namespace Tgstation.Server.Host.Components.Chat
 					channelIdCounter += (ulong)results.Count;
 				}
 
-				Task trackingContextUpdateTask;
 				lock (mappedChannels)
 				{
 					lock (providers)
@@ -245,16 +244,9 @@ namespace Tgstation.Server.Host.Components.Chat
 						mappedChannels.Add(newId, newMapping);
 						newMapping.Channel.RealId = newId;
 					}
-
-					lock (trackingContexts)
-						trackingContextUpdateTask = Task.WhenAll(
-							trackingContexts.Select(
-								x => x.UpdateChannels(
-									mappedChannels.Select(y => y.Value.Channel).ToList(),
-									cancellationToken)));
 				}
 
-				await trackingContextUpdateTask;
+				await UpdateTrackingContexts(cancellationToken);
 			}
 			finally
 			{
@@ -472,6 +464,18 @@ namespace Tgstation.Server.Host.Components.Chat
 			return context;
 		}
 
+		/// <inheritdoc />
+		public Task UpdateTrackingContexts(CancellationToken cancellationToken)
+		{
+			lock (mappedChannels)
+				lock (trackingContexts)
+					return Task.WhenAll(
+						trackingContexts.Select(
+							x => x.UpdateChannels(
+								mappedChannels.Select(y => y.Value.Channel).ToList(),
+								cancellationToken)));
+		}
+
 		/// <inheritdoc />
 		public void RegisterCommandHandler(ICustomCommandHandler customCommandHandler)
 		{

src/Tgstation.Server.Host/Components/Chat/IChatManager.cs

@@ -84,5 +84,12 @@ namespace Tgstation.Server.Host.Components.Chat
 		/// </summary>
 		/// <returns>A new <see cref="IChatTrackingContext"/>.</returns>
 		IChatTrackingContext CreateTrackingContext();
+
+		/// <summary>
+		/// Force an update with the active channels on all active <see cref="IChatTrackingContext"/>s.
+		/// </summary>
+		/// <param name="cancellationToken">The <see cref="CancellationToken"/> for the operation.</param>
+		/// <returns>A <see cref="Task"/> representing the running operation.</returns>
+		Task UpdateTrackingContexts(CancellationToken cancellationToken);
 	}
 }

src/Tgstation.Server.Host/Components/Watchdog/WatchdogBase.cs

@@ -384,8 +384,11 @@ namespace Tgstation.Server.Host.Components.Watchdog
 				{
 					if (core.Watchdog != this)
 						throw new InvalidOperationException(Instance.DifferentCoreExceptionMessage);
+
 					using (await SemaphoreSlimContext.Lock(synchronizationSemaphore, ct))
 						await LaunchNoLock(true, true, true, reattachInfo, ct);
+
+					await Chat.UpdateTrackingContexts(ct);
 				},
 				cancellationToken)
 				;