fix: animations modifying animations during callback is now safe

tests/regression/recursive_animation_callback_segfault.py

@@ -0,0 +1,46 @@
+# Regression test: Recursive animation callbacks
+# Issue: Animation callbacks that started new animations caused segfault in AnimationManager::update
+# Fixed by: Deferring animation removal during update loop iteration
+#
+# This test verifies that:
+# 1. Animation callbacks can start new animations on the same property (REPLACE mode)
+# 2. No segfault occurs from iterator invalidation
+# 3. The animation chain completes properly
+
+import mcrfpy
+import sys
+
+scene = mcrfpy.Scene("test")
+mcrfpy.current_scene = scene
+
+frame = mcrfpy.Frame(pos=(100, 100), size=(50, 50), fill_color=mcrfpy.Color(255, 0, 0))
+scene.children.append(frame)
+
+callback_count = 0
+MAX_CALLBACKS = 10
+
+def recursive_callback(target, prop, value):
+    """Animation callback that starts another animation on the same property"""
+    global callback_count
+    callback_count += 1
+
+    if callback_count >= MAX_CALLBACKS:
+        print(f"PASS - {callback_count} recursive animation callbacks completed without segfault")
+        sys.exit(0)
+
+    # Chain another animation - this used to cause segfault due to iterator invalidation
+    target.animate("x", 100 + (callback_count * 20), 0.1, mcrfpy.Easing.LINEAR, callback=recursive_callback)
+
+# Start the chain
+frame.animate("x", 200, 0.1, mcrfpy.Easing.LINEAR, callback=recursive_callback)
+
+def timeout_check(timer, runtime):
+    """Safety timeout"""
+    if callback_count >= MAX_CALLBACKS:
+        print(f"PASS - {callback_count} callbacks completed")
+        sys.exit(0)
+    else:
+        print(f"FAIL - only {callback_count}/{MAX_CALLBACKS} callbacks executed")
+        sys.exit(1)
+
+safety_timer = mcrfpy.Timer("safety", timeout_check, 5000, once=True)