fix: align chat agent with langgraph dev runtime

Author: blove

examples/chat-agent/pyproject.toml

@@ -12,7 +12,7 @@ dependencies = [
 [tool.uv]
 dev-dependencies = [
     "pytest>=8.0",
-    "langgraph-cli>=0.1",
+    "langgraph-cli[inmem]>=0.1",
 ]
 
 [build-system]

examples/chat-agent/src/chat_agent/agent.py

@@ -5,7 +5,6 @@
 from dotenv import load_dotenv
 from langchain_core.messages import SystemMessage
 from langchain_core.runnables import RunnableConfig
-from langgraph.checkpoint.memory import MemorySaver
 from langgraph.graph import END, START, MessagesState, StateGraph
 
 from chat_agent.config import Configuration
@@ -40,5 +39,6 @@ def call_model(state: MessagesState, config: RunnableConfig) -> dict:
 _builder.add_edge(START, "call_model")
 _builder.add_edge("call_model", END)
 
-# Compile with MemorySaver — persists thread state for the server lifetime
-graph = _builder.compile(checkpointer=MemorySaver())
+# LangGraph API manages persistence for deployed graphs, so keep the exported
+# graph free of a custom checkpointer.
+graph = _builder.compile()

examples/chat-agent/tests/test_agent_integration.py

@@ -28,8 +28,8 @@ def test_single_turn():
 
 @pytest.mark.integration
 @pytest.mark.skipif(not os.getenv("OPENAI_API_KEY"), reason=SKIP_REASON)
-def test_thread_persistence():
-    """MemorySaver persists messages across invocations on the same thread_id."""
+def test_repeated_invocation_with_thread_id():
+    """Repeated calls with the same thread_id should still produce valid responses."""
     from langchain_core.messages import AIMessage, HumanMessage
     from chat_agent.agent import graph
 
@@ -46,4 +46,4 @@ def test_thread_persistence():
     )
     last = result["messages"][-1]
     assert isinstance(last, AIMessage)
-    assert "PINEAPPLE" in last.content
+    assert len(last.content) > 0

examples/chat-agent/tests/test_agent_smoke.py

@@ -66,3 +66,22 @@ def test_graph_import_does_not_import_langchain_openai():
     spec.loader.exec_module(module)
 
     assert "langchain_openai" not in sys.modules
+
+
+@pytest.mark.smoke
+def test_graph_does_not_define_a_custom_checkpointer():
+    """LangGraph API manages persistence itself, so the exported graph should not set one."""
+    agent_path = Path(__file__).resolve().parents[1] / "src" / "chat_agent" / "agent.py"
+
+    import sys
+
+    sys.path.insert(0, str(agent_path.parents[1] / "src"))
+
+    spec = spec_from_file_location("deployed_agent_no_checkpointer", agent_path)
+    assert spec is not None
+    assert spec.loader is not None
+
+    module = module_from_spec(spec)
+    spec.loader.exec_module(module)
+
+    assert getattr(module.graph, "checkpointer", None) is None