fix(websocket): stop LogCallbackEvent broadcast recursion in shutdown

CHANGELOG.md

@@ -12,6 +12,26 @@ pulls notes from — it's the minimum, the GitHub release page is the maximum.
 
 ## [Unreleased]
 
+### Fixed
+
+- **No more stack overflow from `LogCallbackEvent` re-entrancy during
+  shutdown.** `EventBroadcaster` subscribed to `LogCallbackEvent` and
+  broadcast each fired log message over the WebSocket. When KC was
+  mid-shutdown and the WebSocket manager had already stopped, the
+  inner `Broadcast` threw ("The current state of the manager is not
+  Start.") and the catch block called `Log.Warning(...)` — which fired
+  another `LogCallbackEvent`, re-entered the same subscriber, threw
+  again, logged again, and recursed until the stack overflowed and KC
+  crashed. Observed live on a Windows prod box: a botched
+  `GracefulRestart` left the WS manager stopped while the event bus
+  was still alive, and KC logged "Error in event handler for
+  LogCallbackEvent: The requested operation caused a stack overflow."
+  dozens of times before the service died. Fix: a `[ThreadStatic]`
+  re-entrancy guard scoped to the `LogCallbackEvent` path only (other
+  events don't loop back into the logger), and the failure path on
+  that path writes to `Console.Error` instead of `Log.Warning` so the
+  recursion can't restart.
+
 ## [2.8.1] - 2026-05-29
 
 > [Full notes](https://github.com/Kitsune-Den/KitsuneCommand/releases/tag/v2.8.1)

src/KitsuneCommand/WebSocket/EventBroadcaster.cs

@@ -15,6 +15,29 @@ public static class EventBroadcaster
             ContractResolver = new Newtonsoft.Json.Serialization.CamelCasePropertyNamesContractResolver()
         };
 
+        /// <summary>
+        /// Thread-local re-entrancy guard for <see cref="LogCallbackEvent"/> only.
+        ///
+        /// 7DTD routes its Log.* writes through the same logging chain that fires
+        /// LogCallbackEvent. If Broadcast() throws while handling a LogCallbackEvent
+        /// (typical during shutdown once the WebSocketServer manager has stopped:
+        /// "The current state of the manager is not Start.") and we then call
+        /// Log.Warning(...) to report it, that Log.Warning fires another
+        /// LogCallbackEvent, re-enters this subscriber, throws again, logs again,
+        /// and recurses until the stack overflows and KC crashes.
+        ///
+        /// Observed live on a Windows prod box: a botched GracefulRestart left the
+        /// WS manager stopped while the event bus was still alive, and KC logged
+        /// "Error in event handler for LogCallbackEvent: The requested operation
+        /// caused a stack overflow." dozens of times before the service died.
+        ///
+        /// Scope is intentionally narrow: other event types don't loop back into
+        /// the logger from their failure path, so they keep the normal
+        /// Log.Warning-on-failure behavior to surface real broadcast bugs.
+        /// </summary>
+        [ThreadStatic]
+        private static bool _inLogBroadcast;
+
         public static void Initialize(WebSocketServer server, ModEventBus eventBus)
         {
             _server = server;
@@ -32,15 +55,41 @@ public static void Initialize(WebSocketServer server, ModEventBus eventBus)
             eventBus.Subscribe<EntityKilledEvent>(e => Broadcast("EntityKilled", e));
             eventBus.Subscribe<ChatMessageEvent>(e => Broadcast("ChatMessage", e));
             eventBus.Subscribe<SkyChangedEvent>(e => Broadcast("SkyChanged", e));
-            eventBus.Subscribe<LogCallbackEvent>(e => Broadcast("LogCallback", e));
+            eventBus.Subscribe<LogCallbackEvent>(BroadcastLogCallback);
             eventBus.Subscribe<PlayersPositionUpdateEvent>(e => Broadcast("PlayersPositionUpdate", e));
             eventBus.Subscribe<PointsUpdateEvent>(e => Broadcast("PointsUpdate", e));
             eventBus.Subscribe<BloodMoonVoteUpdateEvent>(e => Broadcast("BloodMoonVoteUpdate", e));
             eventBus.Subscribe<TicketCreatedEvent>(e => Broadcast("TicketCreated", e));
             eventBus.Subscribe<TicketUpdatedEvent>(e => Broadcast("TicketUpdated", e));
         }
 
-        private static void Broadcast<T>(string eventType, T data)
+        /// <summary>
+        /// Re-entrancy-safe LogCallbackEvent broadcaster.
+        ///
+        /// If we're already inside a LogCallbackEvent broadcast on this thread,
+        /// drop the event silently — anything we'd log here would just fire
+        /// another LogCallbackEvent and we'd be back to the recursion bug this
+        /// guard exists to prevent. Likewise, if the inner broadcast throws,
+        /// we deliberately do NOT route the failure through Log.Warning.
+        /// Console.Error.WriteLine is the closest we'll get to surfacing it,
+        /// and even that is wasted noise during shutdown — but it's bounded.
+        /// </summary>
+        internal static void BroadcastLogCallback(LogCallbackEvent e)
+        {
+            if (_inLogBroadcast) return;
+
+            _inLogBroadcast = true;
+            try
+            {
+                Broadcast("LogCallback", e, suppressFailureLogging: true);
+            }
+            finally
+            {
+                _inLogBroadcast = false;
+            }
+        }
+
+        private static void Broadcast<T>(string eventType, T data, bool suppressFailureLogging = false)
         {
             if (_server == null) return;
 
@@ -58,7 +107,25 @@ private static void Broadcast<T>(string eventType, T data)
             catch (Exception ex)
             {
                 // Don't let broadcast failures crash the game
-                Log.Warning($"[KitsuneCommand] Broadcast error for {eventType}: {ex.Message}");
+                if (suppressFailureLogging)
+                {
+                    // LogCallbackEvent path: Log.* feeds back into the broadcaster,
+                    // so any logger call here is a recursion hazard. Use the bare
+                    // Console.Error channel instead — bounded and won't re-enter.
+                    try
+                    {
+                        Console.Error.WriteLine(
+                            $"[KitsuneCommand] Broadcast error for {eventType}: {ex.Message}");
+                    }
+                    catch
+                    {
+                        // Last-resort: stderr itself failed. Nothing safe left to do.
+                    }
+                }
+                else
+                {
+                    Log.Warning($"[KitsuneCommand] Broadcast error for {eventType}: {ex.Message}");
+                }
             }
         }
     }