diff --git a/src/memu/database/inmemory/repositories/memory_item_repo.py b/src/memu/database/inmemory/repositories/memory_item_repo.py
index da28e14f..a4442463 100644
--- a/src/memu/database/inmemory/repositories/memory_item_repo.py
+++ b/src/memu/database/inmemory/repositories/memory_item_repo.py
@@ -79,7 +79,7 @@ def _find_by_hash(self, content_hash: str, user_data: dict[str, Any]) -> MemoryI
     def create_item(
         self,
         *,
-        resource_id: str,
+        resource_id: str | None = None,
         memory_type: MemoryType,
         summary: str,
         embedding: list[float],
@@ -122,7 +122,7 @@ def create_item(
     def create_item_reinforce(
         self,
         *,
-        resource_id: str,
+        resource_id: str | None = None,
         memory_type: MemoryType,
         summary: str,
         embedding: list[float],
diff --git a/src/memu/database/repositories/memory_item.py b/src/memu/database/repositories/memory_item.py
index 39bb856b..a2124005 100644
--- a/src/memu/database/repositories/memory_item.py
+++ b/src/memu/database/repositories/memory_item.py
@@ -21,7 +21,7 @@ def clear_items(self, where: Mapping[str, Any] | None = None) -> dict[str, Memor
     def create_item(
         self,
         *,
-        resource_id: str,
+        resource_id: str | None = None,
         memory_type: MemoryType,
         summary: str,
         embedding: list[float],
diff --git a/src/memu/database/sqlite/repositories/memory_item_repo.py b/src/memu/database/sqlite/repositories/memory_item_repo.py
index 0bff124e..1ca32481 100644
--- a/src/memu/database/sqlite/repositories/memory_item_repo.py
+++ b/src/memu/database/sqlite/repositories/memory_item_repo.py
@@ -211,7 +211,7 @@ def clear_items(self, where: Mapping[str, Any] | None = None) -> dict[str, Memor
     def create_item(
         self,
         *,
-        resource_id: str,
+        resource_id: str | None = None,
         memory_type: MemoryType,
         summary: str,
         embedding: list[float],
@@ -285,7 +285,7 @@ def create_item(
     def create_item_reinforce(
         self,
         *,
-        resource_id: str,
+        resource_id: str | None = None,
         memory_type: MemoryType,
         summary: str,
         embedding: list[float],