fix: Resolve mypy lint errors

- Use isinstance(gen, ChatGeneration) to type-narrow in callback handler
- Declare model as Any to accommodate Runnable return type from bind_tools
- Fix bind_kwargs type annotation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: jsonbailey

packages/ai-providers/server-ai-langchain/src/ldai_langchain/langgraph_agent_graph_runner.py

@@ -141,10 +141,11 @@ def handle_traversal(node: AgentGraphNode, ctx: dict) -> None:
                     handoff_fns.append(_make_handoff_tool(edge.target_config, description))
 
             all_tools = tool_fns + handoff_fns
+            model: Any
             if lc_model and all_tools:
                 # When handoff tools are present, disable parallel tool calls so the LLM
                 # picks exactly one destination rather than routing to multiple children.
-                bind_kwargs = {'parallel_tool_calls': False} if handoff_fns else {}
+                bind_kwargs: Dict[str, Any] = {'parallel_tool_calls': False} if handoff_fns else {}
                 model = lc_model.bind_tools(all_tools, **bind_kwargs)
             else:
                 model = lc_model

packages/ai-providers/server-ai-langchain/src/ldai_langchain/langgraph_callback_handler.py

@@ -3,7 +3,7 @@
 from uuid import UUID
 
 from langchain_core.callbacks import BaseCallbackHandler
-from langchain_core.outputs import LLMResult
+from langchain_core.outputs import ChatGeneration, LLMResult
 from ldai.agent_graph import AgentGraphDefinition
 from ldai.tracker import TokenUsage
 
@@ -140,9 +140,12 @@ def on_llm_end(
             return
 
         try:
-            message = response.generations[0][0].message
-        except (IndexError, AttributeError, TypeError):
+            gen = response.generations[0][0]
+        except (IndexError, TypeError):
             return
+        if not isinstance(gen, ChatGeneration):
+            return
+        message = gen.message
         usage = get_ai_usage_from_response(message)
         if usage is None:
             return
@@ -215,4 +218,3 @@ def flush(self, graph: AgentGraphDefinition, graph_tracker: Any) -> None:
 
             for tool_key in self._node_tool_calls.get(node_key, []):
                 config_tracker.track_tool_call(tool_key, graph_key=gk)
-