Fix GraphConfigLoader to handle nested config top-level key requirements

- Wrap agent configs in 'agent:' key when loading graph nodes
- Wrap swarm configs in 'swarm:' key when loading graph nodes
- Wrap graph configs in 'graph:' key when loading nested graphs
- Fixes compatibility with ConfigLoader top-level key requirements
- Resolves graph loading errors in configuration-driven systems

Fixes issue where graph nodes failed to load with:
'Configuration must contain a top-level agent/swarm/graph key'

Author: vawsgit

src/strands/experimental/config_loader/graph/graph_config_loader.py

@@ -214,8 +214,10 @@ def _load_nodes(self, nodes_config: List[Dict[str, Any]]) -> Dict[str, GraphNode
             if node_type == "agent":
                 if "config" in node_config:
                     # Load agent from configuration
+                    # Wrap the agent config in the required top-level 'agent' key
                     agent_loader = self._get_agent_config_loader()
-                    agent = agent_loader.load_agent(node_config["config"])
+                    wrapped_agent_config = {"agent": node_config["config"]}
+                    agent = agent_loader.load_agent(wrapped_agent_config)
                 elif "reference" in node_config:
                     # Load agent from reference (string identifier)
                     agent = self._load_agent_reference(node_config["reference"])
@@ -227,8 +229,10 @@ def _load_nodes(self, nodes_config: List[Dict[str, Any]]) -> Dict[str, GraphNode
             elif node_type == "swarm":
                 if "config" in node_config:
                     # Load swarm from configuration
+                    # Wrap the swarm config in the required top-level 'swarm' key
                     swarm_loader = self._get_swarm_config_loader()
-                    swarm = swarm_loader.load_swarm(node_config["config"])
+                    wrapped_swarm_config = {"swarm": node_config["config"]}
+                    swarm = swarm_loader.load_swarm(wrapped_swarm_config)
                 elif "reference" in node_config:
                     # Load swarm from reference
                     swarm = self._load_swarm_reference(node_config["reference"])
@@ -240,7 +244,9 @@ def _load_nodes(self, nodes_config: List[Dict[str, Any]]) -> Dict[str, GraphNode
             elif node_type == "graph":
                 if "config" in node_config:
                     # Recursive graph loading
-                    sub_graph = self.load_graph(node_config["config"])
+                    # Wrap the graph config in the required top-level 'graph' key
+                    wrapped_graph_config = {"graph": node_config["config"]}
+                    sub_graph = self.load_graph(wrapped_graph_config)
                 elif "reference" in node_config:
                     # Load graph from reference
                     sub_graph = self._load_graph_reference(node_config["reference"])