InjectedStore

Example:

from typing_extensions import Annotated
from langgraph.store.memory import InMemoryStore
from langchain.tools import InjectedStore, ToolNode, tool

@tool
def save_preference(
    key: str,
    value: str,
    store: Annotated[Any, InjectedStore()]
) -> str:
    """Save user preference to persistent storage."""
    store.put(("preferences",), key, value)
    return f"Saved {key} = {value}"

@tool
def get_preference(
    key: str,
    store: Annotated[Any, InjectedStore()]
) -> str:
    """Retrieve user preference from persistent storage."""
    result = store.get(("preferences",), key)
    return result.value if result else "Not found"

Usage with ToolNode and graph compilation:

from langgraph.graph import StateGraph
from langgraph.store.memory import InMemoryStore

store = InMemoryStore()
tool_node = ToolNode([save_preference, get_preference])

graph = StateGraph(State)
graph.add_node("tools", tool_node)
compiled_graph = graph.compile(store=store)  # Store is injected automatically

Cross-session persistence:

# First session
result1 = graph.invoke({"messages": [HumanMessage("Save my favorite color as blue")]})

# Later session - data persists
result2 = graph.invoke({"messages": [HumanMessage("What's my favorite color?")]})

• InjectedStore arguments are automatically excluded from tool schemas presented to language models
• The store instance is automatically injected by ToolNode during execution
• Tools can access namespaced storage using the store's get/put methods
• Store injection requires the graph to be compiled with a store instance
• Multiple tools can share the same store instance for data consistency