Update libs/langgraph-checkpoint-aws/langgraph_checkpoint_aws/store/dynamodb/base.py

Co-authored-by: Copilot <[email protected]>

Author: 5enxia

libs/langgraph-checkpoint-aws/langgraph_checkpoint_aws/store/dynamodb/base.py

@@ -278,23 +278,34 @@ def _construct_composite_key(
         Returns:
             Tuple of (PK, SK) for DynamoDB.
         """
-        namespace_str = ":".join(namespace)
+        # Serialize namespace tuple as JSON string for unambiguous encoding
+        namespace_str = orjson.dumps(namespace).decode("utf-8")
         return (namespace_str, key)
 
     def _deconstruct_namespace(self, namespace: str) -> tuple[str, ...]:
         """Deconstruct namespace string back to tuple.
 
         Args:
-            namespace: Namespace string (e.g., "users:123").
+            namespace: Namespace string (JSON-encoded).
 
         Returns:
             Namespace tuple (e.g., ("users", "123")).
         """
         if not namespace:
             return ()
-        if ":" in namespace:
-            return tuple(namespace.split(":"))
-        return (namespace,)
+        try:
+            # Deserialize JSON string back to tuple
+            ns = orjson.loads(namespace)
+            # Ensure result is tuple
+            if isinstance(ns, (list, tuple)):
+                return tuple(ns)
+            # Fallback: single string
+            return (str(ns),)
+        except Exception:
+            # Fallback for legacy colon-separated format
+            if ":" in namespace:
+                return tuple(namespace.split(":"))
+            return (namespace,)
 
     def _map_to_item(self, result_dict: dict[str, Any], item_type: type = Item) -> Item:
         """Map DynamoDB item to store Item.