[langgraph]: graph.get_state_history(config) cannot output the complete snapshot history

[wanjundegithub]

Type of issue

issue / bug

Language

Python

Description

`class State(TypedDict):
foo:str
bar:Annotated[list[str], add]

def node_a(state:State):
return {"foo":"a", "bar":["a"]}

def node_b(state:State):
return {"foo":"b", "bar":["b"]}

persistence_builder = StateGraph(State)
persistence_builder.add_edge(START, "node_a")
persistence_builder.add_node(node_a)
persistence_builder.add_node(node_b)
persistence_builder.add_edge("node_a", "node_b")
persistence_builder.add_edge("node_b", END)

check_pointer = InMemorySaver()
persistence_graph = persistence_builder.compile(checkpointer=check_pointer)

config:RunnableConfig = {"configurable": {"thread_id": "1"}}

state = persistence_graph.invoke({"foo":""}, config)

print(list(persistence_graph.get_state_history(config)))
`

output: [StateSnapshot(values={'foo': 'b', 'bar': ['a', 'b']}, next=(), config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f0a5883-f508-6445-8002-701f70e8f22a'}}, metadata={'source': 'loop', 'step': 2, 'parents': {}}, created_at='2025-10-10T03:21:44.486179+00:00', parent_config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f0a5883-f4f8-67af-8001-ce8aef2b5253'}}, tasks=(), interrupts=()), StateSnapshot(values={'foo': 'a', 'bar': ['a']}, next=('node_b',), config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f0a5883-f4f8-67af-8001-ce8aef2b5253'}}, metadata={'source': 'loop', 'step': 1, 'parents': {}}, created_at='2025-10-10T03:21:44.479705+00:00', parent_config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f0a5883-f4e7-6fb6-8000-87ba2ef2d74a'}}, tasks=(PregelTask(id='102ccb05-ebba-0be7-a94a-43774140780c', name='node_b', path=('__pregel_pull', 'node_b'), error=None, interrupts=(), state=None, result={'foo': 'b', 'bar': ['b']}),), interrupts=()), StateSnapshot(values={'foo': '', 'bar': []}, next=('node_a',), config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f0a5883-f4e7-6fb6-8000-87ba2ef2d74a'}}, metadata={'source': 'loop', 'step': 0, 'parents': {}}, created_at='2025-10-10T03:21:44.472932+00:00', parent_config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f0a5883-f4e3-640a-bfff-8ec73f5fda2a'}}, tasks=(PregelTask(id='bb822f24-ead6-bb34-ad7a-bae03c77ac0f', name='node_a', path=('__pregel_pull', 'node_a'), error=None, interrupts=(), state=None, result={'foo': 'a', 'bar': ['a']}),), interrupts=()), StateSnapshot(values={'bar': []}, next=('start',), config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f0a5883-f4e3-640a-bfff-8ec73f5fda2a'}}, metadata={'source': 'input', 'step': -1, 'parents': {}}, created_at='2025-10-10T03:21:44.471016+00:00', parent_config=None, tasks=(PregelTask(id='e406c385-4665-8ad2-ed2c-4fb5200cc0bb', name='start', path=('__pregel_pull', 'start'), error=None, interrupts=(), state=None, result={'foo': ''}),), interrupts=())]
Client disconnected

only this code works:
for event in persistence_graph.stream({"foo": ""}, config): if isinstance(event, dict): for node_name, result in event.items(): print(f"Node: {node_name}") print("Partial:", result) print("Merged:", persistence_graph.get_state(config).values) print("-----")