Fix weak DI container memory leak

src/core/di/weak_container.py

@@ -71,12 +71,19 @@ def register_instance(
         if cleanup_callback:
             self._cleanup_callbacks[service_type] = cleanup_callback
 
-            # Set up weak reference callback for cleanup
-            def on_delete(ref):
+            instance_ref = weakref.ref(instance)
+
+            # Set up weak reference callback for cleanup without strong reference cycles
+            def on_delete(_: weakref.ReferenceType[Any]) -> None:
+                service_instance = instance_ref()
+                if service_instance is None:
+                    return
                 try:
-                    cleanup_callback(instance)
-                except Exception as e:
-                    logger.warning(f"Error in cleanup callback for {service_type}: {e}")
+                    cleanup_callback(service_instance)
+                except Exception as exc:
+                    logger.warning(
+                        f"Error in cleanup callback for {service_type}: {exc}",
+                    )
 
             weakref.ref(instance, on_delete)
 
@@ -123,13 +130,17 @@ async def get_service(self, service_type: type[T]) -> T:
                     # Set up cleanup callback if registered
                     cleanup_callback = self._cleanup_callbacks.get(service_type)
                     if cleanup_callback:
+                        instance_ref = weakref.ref(instance)
 
-                        def on_delete(ref):
+                        def on_delete(_: weakref.ReferenceType[Any]) -> None:
+                            service_instance = instance_ref()
+                            if service_instance is None:
+                                return
                             try:
-                                cleanup_callback(instance)
-                            except Exception as e:
+                                cleanup_callback(service_instance)
+                            except Exception as exc:
                                 logger.warning(
-                                    f"Error in cleanup callback for {service_type}: {e}"
+                                    f"Error in cleanup callback for {service_type}: {exc}",
                                 )
 
                         weakref.ref(instance, on_delete)

tests/unit/core/di/test_weak_container.py

@@ -0,0 +1,36 @@
+"""Tests for the weak DI container memory management."""
+
+from __future__ import annotations
+
+import gc
+import weakref
+
+import pytest
+from src.core.di.weak_container import WeakDIContainer
+
+
+class _DummyService:
+    """Simple service used to verify garbage collection behavior."""
+
+
+@pytest.mark.asyncio
+async def test_weak_container_allows_garbage_collection() -> None:
+    """Instances registered in the weak container should not be leaked."""
+
+    container = WeakDIContainer()
+
+    def factory() -> _DummyService:
+        return _DummyService()
+
+    container.register_factory(_DummyService, factory)
+
+    service = await container.get_service(_DummyService)
+    service_ref = weakref.ref(service)
+
+    # Drop the strong reference held by the test
+    del service
+
+    # Force garbage collection to trigger weakref callbacks
+    gc.collect()
+
+    assert service_ref() is None