From 99d3da467e6dfc57e5ebc96606f839c5340abbe9 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Tue, 24 Mar 2026 17:45:06 +0100
Subject: [PATCH] Fix deadlock when hot-reloading scripts in Editor while
 `Animation` asset gets auto-saved

#3942
---
 Source/Engine/Content/Assets/Animation.cpp | 23 +++++++++++++++++-----
 Source/Engine/Content/Assets/Animation.h   |  4 ++++
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/Source/Engine/Content/Assets/Animation.cpp b/Source/Engine/Content/Assets/Animation.cpp
index 917db28ac..86fa41f89 100644
--- a/Source/Engine/Content/Assets/Animation.cpp
+++ b/Source/Engine/Content/Assets/Animation.cpp
@@ -691,11 +691,7 @@ Asset::LoadResult Animation::load()
                     continue;
                 }
 #if USE_EDITOR
-                if (!_registeredForScriptingReload)
-                {
-                    _registeredForScriptingReload = true;
-                    Level::ScriptsReloadStart.Bind<Animation, &Animation::OnScriptsReloadStart>(this);
-                }
+                _registerForScriptingReload = true;
 #endif
             }
         }
@@ -733,6 +729,7 @@ void Animation::unload(bool isReloading)
 {
     ScopeWriteLock systemScope(Animations::SystemLocker);
 #if USE_EDITOR
+    _registerForScriptingReload = false;
     if (_registeredForScriptingReload)
     {
         _registeredForScriptingReload = false;
@@ -752,6 +749,22 @@ void Animation::unload(bool isReloading)
     NestedAnims.Clear();
 }
 
+#if USE_EDITOR
+
+void Animation::onLoaded_MainThread()
+{
+    if (_registerForScriptingReload && !_registeredForScriptingReload)
+    {
+        _registeredForScriptingReload = true;
+        Level::ScriptsReloadStart.Bind<Animation, &Animation::OnScriptsReloadStart>(this);
+    }
+    _registerForScriptingReload = false;
+
+    BinaryAsset::onLoaded_MainThread();
+}
+
+#endif
+
 AssetChunksFlag Animation::getChunksToPreload() const
 {
     return GET_CHUNK_FLAG(0);
diff --git a/Source/Engine/Content/Assets/Animation.h b/Source/Engine/Content/Assets/Animation.h
index 4f4a773b4..c342cc64c 100644
--- a/Source/Engine/Content/Assets/Animation.h
+++ b/Source/Engine/Content/Assets/Animation.h
@@ -78,6 +78,7 @@ API_CLASS(NoSpawn) class FLAXENGINE_API Animation : public BinaryAsset
 
 private:
 #if USE_EDITOR
+    bool _registerForScriptingReload = false;
     bool _registeredForScriptingReload = false;
     void OnScriptsReloadStart();
 #endif
@@ -163,5 +164,8 @@ protected:
     // [BinaryAsset]
     LoadResult load() override;
     void unload(bool isReloading) override;
+#if USE_EDITOR
+    void onLoaded_MainThread() override;
+#endif
     AssetChunksFlag getChunksToPreload() const override;
 };