x

Move unit tests for ToolNode into the tool node testing code

docs/docs/agents/multi-agent.md

@@ -367,13 +367,13 @@ To implement handoffs with `createReactAgent`, you need to:
 
 3.  Define a parent graph that contains individual agents as nodes:
 
-        ```typescript
-        import { StateGraph, MessagesZodState } from "@langchain/langgraph";
-        const multiAgentGraph = new StateGraph(MessagesZodState)
-          .addNode("flight_assistant", flightAssistant)
-          .addNode("hotel_assistant", hotelAssistant)
-          // ...
-        ```
+    ```typescript
+    import { StateGraph, MessagesZodState } from "@langchain/langgraph";
+    const multiAgentGraph = new StateGraph(MessagesZodState)
+      .addNode("flight_assistant", flightAssistant)
+      .addNode("hotel_assistant", hotelAssistant)
+      // ...
+    ```
 
     :::
 
@@ -619,7 +619,8 @@ for await (const chunk of multiAgentGraph.stream({
 3. Name of the agent or node to hand off to.
 4. Take the agent's messages and **add** them to the parent's **state** as part of the handoff. The next agent will see the parent state.
 5. Indicate to LangGraph that we need to navigate to agent node in a **parent** multi-agent graph.
-   :::
+
+:::
 
 !!! Note
 

docs/docs/concepts/mcp.md

@@ -6,7 +6,14 @@
 
 Install the `langchain-mcp-adapters` library to use MCP tools in LangGraph:
 
+:::python
 ```bash
 pip install langchain-mcp-adapters
 ```
+:::
 
+:::js
+```bash
+npm install @langchain/mcp-adapters
+```
+:::

docs/docs/how-tos/multi_agent.md

@@ -22,6 +22,7 @@ To set up communication between the agents in a multi-agent system you can use [
 
 To implement handoffs, you can return `Command` objects from your agent nodes or tools:
 
+:::python
 ```python
 from typing import Annotated
 from langchain_core.tools import tool, InjectedToolCallId
@@ -73,25 +74,109 @@ def create_handoff_tool(*, agent_name: str, description: str | None = None):
         commands = [tools_by_name[tool_call["name"]].invoke(tool_call) for tool_call in tool_calls]
         return commands
     ```
+:::
+
+:::js
+```typescript
+import { tool } from "@langchain/core/tools";
+import { Command, MessagesZodState } from "@langchain/langgraph";
+import { z } from "zod";
+
+function createHandoffTool({
+  agentName,
+  description,
+}: {
+  agentName: string;
+  description?: string;
+}) {
+  const name = `transfer_to_${agentName}`;
+  const toolDescription = description || `Transfer to ${agentName}`;
+
+  return tool(
+    async (_, config) => {
+      // (1)!
+      const state = config.state;
+      const toolCallId = config.toolCall.id;
+
+      const toolMessage = {
+        role: "tool" as const,
+        content: `Successfully transferred to ${agentName}`,
+        name: name,
+        tool_call_id: toolCallId,
+      };
+
+      return new Command({
+        // (3)!
+        goto: agentName,
+        // (4)!
+        update: { messages: [...state.messages, toolMessage] },
+        // (5)!
+        graph: Command.PARENT,
+      });
+    },
+    {
+      name,
+      description: toolDescription,
+      schema: z.object({}),
+    }
+  );
+}
+```
+
+1. Access the [state](../concepts/low_level.md#state) of the agent that is calling the handoff tool through the `config` parameter.
+2. The `Command` primitive allows specifying a state update and a node transition as a single operation, making it useful for implementing handoffs.
+3. Name of the agent or node to hand off to.
+4. Take the agent's messages and **add** them to the parent's **state** as part of the handoff. The next agent will see the parent state.
+5. Indicate to LangGraph that we need to navigate to agent node in a **parent** multi-agent graph.
+
+!!! tip
+
+    If you want to use tools that return `Command`, you can either use prebuilt @[`create_react_agent`][create_react_agent] / @[`ToolNode`][ToolNode] components, or implement your own tool-executing node that collects `Command` objects returned by the tools and returns a list of them, e.g.:
+    
+    ```typescript
+    const callTools = async (state) => {
+      // ...
+      const commands = await Promise.all(
+        toolCalls.map(toolCall => toolsByName[toolCall.name].invoke(toolCall))
+      );
+      return commands;
+    };
+    ```
+:::
 
 !!! Important
 
     This handoff implementation assumes that:
     
-      - each agent receives overall message history (across all agents) in the multi-agent system as its input. If you want more control over agent inputs, see [this section](#control-agent-inputs)
-      - each agent outputs its internal messages history to the overall message history of the multi-agent system. If you want more control over **how agent outputs are added**, wrap the agent in a separate node function:
+    - each agent receives overall message history (across all agents) in the multi-agent system as its input. If you want more control over agent inputs, see [this section](#control-agent-inputs)
+    - each agent outputs its internal messages history to the overall message history of the multi-agent system. If you want more control over **how agent outputs are added**, wrap the agent in a separate node function:
 
-        ```python
-        def call_hotel_assistant(state):
-            # return agent's final response,
-            # excluding inner monologue
-            response = hotel_assistant.invoke(state)
-            # highlight-next-line
-            return {"messages": response["messages"][-1]}
-        ```
+      :::python
+      ```python
+      def call_hotel_assistant(state):
+          # return agent's final response,
+          # excluding inner monologue
+          response = hotel_assistant.invoke(state)
+          # highlight-next-line
+          return {"messages": response["messages"][-1]}
+      ```
+      :::
+
+      :::js
+      ```typescript
+      const callHotelAssistant = async (state) => {
+        // return agent's final response,
+        // excluding inner monologue
+        const response = await hotelAssistant.invoke(state);
+        // highlight-next-line
+        return { messages: [response.messages.at(-1)] };
+      };
+      ```
+      :::
 
 ### Control agent inputs
 
+:::python
 You can use the @[`Send()`][Send] primitive to directly send data to the worker agents during the handoff. For example, you can request that the calling agent populate a task description for the next agent:
 
 ```python
@@ -129,6 +214,63 @@ def create_task_description_handoff_tool(
 
     return handoff_tool
 ```
+:::
+
+:::js
+You can use the @[`Send()`][Send] primitive to directly send data to the worker agents during the handoff. For example, you can request that the calling agent populate a task description for the next agent:
+
+```typescript
+import { tool } from "@langchain/core/tools";
+import { Command, Send, MessagesZodState } from "@langchain/langgraph";
+import { z } from "zod";
+
+function createTaskDescriptionHandoffTool({
+  agentName,
+  description,
+}: {
+  agentName: string;
+  description?: string;
+}) {
+  const name = `transfer_to_${agentName}`;
+  const toolDescription = description || `Ask ${agentName} for help.`;
+
+  return tool(
+    async (
+      { taskDescription },
+      config
+    ) => {
+      const state = config.state;
+      
+      const taskDescriptionMessage = {
+        role: "user" as const,
+        content: taskDescription,
+      };
+      const agentInput = {
+        ...state,
+        messages: [taskDescriptionMessage],
+      };
+      
+      return new Command({
+        // highlight-next-line
+        goto: [new Send(agentName, agentInput)],
+        graph: Command.PARENT,
+      });
+    },
+    {
+      name,
+      description: toolDescription,
+      schema: z.object({
+        taskDescription: z
+          .string()
+          .describe(
+            "Description of what the next agent should do, including all of the relevant context."
+          ),
+      }),
+    }
+  );
+}
+```
+:::
 
 See the multi-agent [supervisor](../tutorials/multi_agent/agent_supervisor.md#4-create-delegation-tasks) example for a full example of using @[`Send()`][Send] in handoffs.
 
@@ -136,6 +278,7 @@ See the multi-agent [supervisor](../tutorials/multi_agent/agent_supervisor.md#4-
 
 You can use handoffs in any agents built with LangGraph. We recommend using the prebuilt [agent](../agents/overview.md) or [`ToolNode`](./tool-calling.md#toolnode), as they natively support handoffs tools returning `Command`. Below is an example of how you can implement a multi-agent system for booking travel using handoffs:
 
+:::python
 ```python
 from langgraph.prebuilt import create_react_agent
 from langgraph.graph import StateGraph, START, MessagesState
@@ -176,9 +319,65 @@ multi_agent_graph = (
     .compile()
 )
 ```
+:::
+
+:::js
+```typescript
+import { createReactAgent } from "@langchain/langgraph/prebuilt";
+import { StateGraph, START, MessagesZodState } from "@langchain/langgraph";
+import { z } from "zod";
+
+function createHandoffTool({
+  agentName,
+  description,
+}: {
+  agentName: string;
+  description?: string;
+}) {
+  // same implementation as above
+  // ...
+  return new Command(/* ... */);
+}
+
+// Handoffs
+const transferToHotelAssistant = createHandoffTool({
+  agentName: "hotel_assistant",
+});
+const transferToFlightAssistant = createHandoffTool({
+  agentName: "flight_assistant",
+});
+
+// Define agents
+const flightAssistant = createReactAgent({
+  llm: model,
+  // highlight-next-line
+  tools: [/* ... */, transferToHotelAssistant],
+  // highlight-next-line
+  name: "flight_assistant",
+});
+
+const hotelAssistant = createReactAgent({
+  llm: model,
+  // highlight-next-line
+  tools: [/* ... */, transferToFlightAssistant],
+  // highlight-next-line
+  name: "hotel_assistant",
+});
+
+// Define multi-agent graph
+const multiAgentGraph = new StateGraph(MessagesZodState)
+  // highlight-next-line
+  .addNode("flight_assistant", flightAssistant)
+  // highlight-next-line
+  .addNode("hotel_assistant", hotelAssistant)
+  .addEdge(START, "flight_assistant")
+  .compile();
+```
+:::
 
 ??? example "Full example: Multi-agent system for booking travel"
 
+    :::python
     ```python
     from typing import Annotated
     from langchain_core.messages import convert_to_messages
@@ -323,6 +522,183 @@ multi_agent_graph = (
     3. Name of the agent or node to hand off to.
     4. Take the agent's messages and **add** them to the parent's **state** as part of the handoff. The next agent will see the parent state.
     5. Indicate to LangGraph that we need to navigate to agent node in a **parent** multi-agent graph.
+    :::
+
+    :::js
+    ```typescript
+    import { tool } from "@langchain/core/tools";
+    import { createReactAgent } from "@langchain/langgraph/prebuilt";
+    import { StateGraph, START, MessagesZodState, Command } from "@langchain/langgraph";
+    import { ChatAnthropic } from "@langchain/anthropic";
+    import { isBaseMessage } from "@langchain/core/messages";
+    import { z } from "zod";
+
+    // We'll use a helper to render the streamed agent outputs nicely
+    const prettyPrintMessages = (update: Record<string, any>) => {
+      // Handle tuple case with namespace
+      if (Array.isArray(update)) {
+        const [ns, updateData] = update;
+        // Skip parent graph updates in the printouts
+        if (ns.length === 0) {
+          return;
+        }
+
+        const graphId = ns[ns.length - 1].split(":")[0];
+        console.log(`Update from subgraph ${graphId}:\n`);
+        update = updateData;
+      }
+
+      for (const [nodeName, updateValue] of Object.entries(update)) {
+        console.log(`Update from node ${nodeName}:\n`);
+
+        const messages = updateValue.messages || [];
+        for (const message of messages) {
+          if (isBaseMessage(message)) {
+            const textContent =
+              typeof message.content === "string"
+                ? message.content
+                : JSON.stringify(message.content);
+            console.log(`${message.getType()}: ${textContent}`);
+          }
+        }
+        console.log("\n");
+      }
+    };
+
+    function createHandoffTool({
+      agentName,
+      description,
+    }: {
+      agentName: string;
+      description?: string;
+    }) {
+      const name = `transfer_to_${agentName}`;
+      const toolDescription = description || `Transfer to ${agentName}`;
+
+      return tool(
+        async (_, config) => {
+          // highlight-next-line
+          const state = config.state; // (1)!
+          const toolCallId = config.toolCall.id;
+
+          const toolMessage = {
+            role: "tool" as const,
+            content: `Successfully transferred to ${agentName}`,
+            name: name,
+            tool_call_id: toolCallId,
+          };
+
+          return new Command({
+            // highlight-next-line
+            goto: agentName, // (3)!
+            // highlight-next-line
+            update: { messages: [...state.messages, toolMessage] }, // (4)!
+            // highlight-next-line
+            graph: Command.PARENT, // (5)!
+          });
+        },
+        {
+          name,
+          description: toolDescription,
+          schema: z.object({}),
+        }
+      );
+    }
+
+    // Handoffs
+    const transferToHotelAssistant = createHandoffTool({
+      agentName: "hotel_assistant",
+      description: "Transfer user to the hotel-booking assistant.",
+    });
+
+    const transferToFlightAssistant = createHandoffTool({
+      agentName: "flight_assistant",
+      description: "Transfer user to the flight-booking assistant.",
+    });
+
+    // Simple agent tools
+    const bookHotel = tool(
+      async ({ hotelName }) => {
+        return `Successfully booked a stay at ${hotelName}.`;
+      },
+      {
+        name: "book_hotel",
+        description: "Book a hotel",
+        schema: z.object({
+          hotelName: z.string(),
+        }),
+      }
+    );
+
+    const bookFlight = tool(
+      async ({ fromAirport, toAirport }) => {
+        return `Successfully booked a flight from ${fromAirport} to ${toAirport}.`;
+      },
+      {
+        name: "book_flight",
+        description: "Book a flight",
+        schema: z.object({
+          fromAirport: z.string(),
+          toAirport: z.string(),
+        }),
+      }
+    );
+
+    const model = new ChatAnthropic({
+      model: "claude-3-5-sonnet-latest",
+    });
+
+    // Define agents
+    const flightAssistant = createReactAgent({
+      llm: model,
+      // highlight-next-line
+      tools: [bookFlight, transferToHotelAssistant],
+      prompt: "You are a flight booking assistant",
+      // highlight-next-line
+      name: "flight_assistant",
+    });
+
+    const hotelAssistant = createReactAgent({
+      llm: model,
+      // highlight-next-line
+      tools: [bookHotel, transferToFlightAssistant],
+      prompt: "You are a hotel booking assistant",
+      // highlight-next-line
+      name: "hotel_assistant",
+    });
+
+    // Define multi-agent graph
+    const multiAgentGraph = new StateGraph(MessagesZodState)
+      .addNode("flight_assistant", flightAssistant)
+      .addNode("hotel_assistant", hotelAssistant)
+      .addEdge(START, "flight_assistant")
+      .compile();
+
+    // Run the multi-agent graph
+    const stream = await multiAgentGraph.stream(
+      {
+        messages: [
+          {
+            role: "user",
+            content: "book a flight from BOS to JFK and a stay at McKittrick Hotel",
+          },
+        ],
+      },
+      // highlight-next-line
+      { subgraphs: true }
+    );
+
+    for await (const chunk of stream) {
+      prettyPrintMessages(chunk);
+    }
+    ```
+
+    1. Access agent's state
+    2. The `Command` primitive allows specifying a state update and a node transition as a single operation, making it useful for implementing handoffs.
+    3. Name of the agent or node to hand off to.
+    4. Take the agent's messages and **add** them to the parent's **state** as part of the handoff. The next agent will see the parent state.
+    5. Indicate to LangGraph that we need to navigate to agent node in a **parent** multi-agent graph.
+    :::
 
 ## Multi-turn conversation
 
@@ -333,6 +709,7 @@ The agents can then be implemented as nodes in a graph that executes agent steps
 1. **Wait for user input** to continue the conversation, or  
 2. **Route to another agent** (or back to itself, such as in a loop) via a [handoff](#handoffs)
 
+:::python
 ```python
 def human(state) -> Command[Literal["agent", "another_agent"]]:
     """A node for collecting user input."""
@@ -360,6 +737,44 @@ def agent(state) -> Command[Literal["agent", "another_agent", "human"]]:
     else:
         return Command(goto="human") # Go to human node
 ```
+:::
+
+:::js
+```typescript
+import { interrupt, Command } from "@langchain/langgraph";
+
+function human(state: MessagesState): Command {
+  const userInput: string = interrupt("Ready for user input.");
+
+  // Determine the active agent
+  const activeAgent = /* ... */;
+
+  return new Command({
+    update: {
+      messages: [{
+        role: "human",
+        content: userInput,
+      }]
+    },
+    goto: activeAgent,
+  });
+}
+
+function agent(state: MessagesState): Command {
+  // The condition for routing/halting can be anything, e.g. LLM tool call / structured output, etc.
+  const goto = getNextAgent(/* ... */); // 'agent' / 'anotherAgent'
+
+  if (goto) {
+    return new Command({
+      goto,
+      update: { myStateKey: "myStateValue" }
+    });
+  }
+
+  return new Command({ goto: "human" });
+}
+```
+:::
 
 ??? example "Full example: multi-agent system for travel recommendations"
 
@@ -370,6 +785,7 @@ def agent(state) -> Command[Literal["agent", "another_agent", "human"]]:
     * travel_advisor: can help with travel destination recommendations. Can ask hotel_advisor for help.
     * hotel_advisor: can help with hotel recommendations. Can ask travel_advisor for help.
 
+    :::python
     ```python
     from langchain_anthropic import ChatAnthropic
     from langgraph.graph import MessagesState, StateGraph, START
@@ -571,10 +987,267 @@ def agent(state) -> Command[Literal["agent", "another_agent", "human"]]:
     
     Would you like more specific information about any of these activities or would you like to know about other options in the area?
     ```
+    :::
+
+    :::js
+    ```typescript
+    import { ChatAnthropic } from "@langchain/anthropic";
+    import { StateGraph, START, MessagesZodState, Command, interrupt, MemorySaver } from "@langchain/langgraph";
+    import { createReactAgent } from "@langchain/langgraph/prebuilt";
+    import { tool } from "@langchain/core/tools";
+    import { z } from "zod";
+
+    const model = new ChatAnthropic({ model: "claude-3-5-sonnet-latest" });
+
+    const MultiAgentState = MessagesZodState.extend({
+      lastActiveAgent: z.string().optional(),
+    });
+
+    // Define travel advisor tools
+    const getTravelRecommendations = tool(
+      async () => {
+        // Placeholder implementation
+        return "Based on current trends, I recommend visiting Japan, Portugal, or New Zealand.";
+      },
+      {
+        name: "get_travel_recommendations",
+        description: "Get current travel destination recommendations",
+        schema: z.object({}),
+      }
+    );
+
+    const makeHandoffTool = (agentName: string) => {
+      return tool(
+        async (_, config) => {
+          const state = config.state;
+          const toolCallId = config.toolCall.id;
+
+          const toolMessage = {
+            role: "tool" as const,
+            content: `Successfully transferred to ${agentName}`,
+            name: `transfer_to_${agentName}`,
+            tool_call_id: toolCallId,
+          };
+
+          return new Command({
+            goto: agentName,
+            update: { messages: [...state.messages, toolMessage] },
+            graph: Command.PARENT,
+          });
+        },
+        {
+          name: `transfer_to_${agentName}`,
+          description: `Transfer to ${agentName}`,
+          schema: z.object({}),
+        }
+      );
+    };
+
+    const travelAdvisorTools = [
+      getTravelRecommendations,
+      makeHandoffTool("hotel_advisor"),
+    ];
+
+    const travelAdvisor = createReactAgent({
+      llm: model,
+      tools: travelAdvisorTools,
+      prompt: [
+        "You are a general travel expert that can recommend travel destinations (e.g. countries, cities, etc). ",
+        "If you need hotel recommendations, ask 'hotel_advisor' for help. ",
+        "You MUST include human-readable response before transferring to another agent."
+      ].join("")
+    });
+
+    const callTravelAdvisor = async (
+      state: z.infer<typeof MultiAgentState>
+    ): Promise<Command> => {
+      const response = await travelAdvisor.invoke(state);
+      const update = { ...response, lastActiveAgent: "travel_advisor" };
+      return new Command({ update, goto: "human" });
+    };
+
+    // Define hotel advisor tools
+    const getHotelRecommendations = tool(
+      async () => {
+        // Placeholder implementation
+        return "I recommend the Ritz-Carlton for luxury stays or boutique hotels for unique experiences.";
+      },
+      {
+        name: "get_hotel_recommendations",
+        description: "Get hotel recommendations for destinations",
+        schema: z.object({}),
+      }
+    );
+
+    const hotelAdvisorTools = [
+      getHotelRecommendations,
+      makeHandoffTool("travel_advisor"),
+    ];
+
+    const hotelAdvisor = createReactAgent({
+      llm: model,
+      tools: hotelAdvisorTools,
+      prompt: [
+        "You are a hotel expert that can provide hotel recommendations for a given destination. ",
+        "If you need help picking travel destinations, ask 'travel_advisor' for help.",
+        "You MUST include human-readable response before transferring to another agent."
+      ].join("")
+    });
+
+    const callHotelAdvisor = async (
+      state: z.infer<typeof MultiAgentState>
+    ): Promise<Command> => {
+      const response = await hotelAdvisor.invoke(state);
+      const update = { ...response, lastActiveAgent: "hotel_advisor" };
+      return new Command({ update, goto: "human" });
+    };
+
+    const humanNode = async (
+      state: z.infer<typeof MultiAgentState>
+    ): Promise<Command> => {
+      const userInput: string = interrupt("Ready for user input.");
+      const activeAgent = state.lastActiveAgent || "travel_advisor";
+
+      return new Command({
+        update: {
+          messages: [
+            {
+              role: "human",
+              content: userInput,
+            }
+          ]
+        },
+        goto: activeAgent,
+      });
+    };
+
+    const builder = new StateGraph(MultiAgentState)
+      .addNode("travel_advisor", callTravelAdvisor)
+      .addNode("hotel_advisor", callHotelAdvisor)
+      .addNode("human", humanNode)
+      .addEdge(START, "travel_advisor");
+
+    const checkpointer = new MemorySaver();
+    const graph = builder.compile({ checkpointer });
+    ```
+    
+    Let's test a multi turn conversation with this application.
+
+    ```typescript
+    import { v4 as uuidv4 } from "uuid";
+    import { Command } from "@langchain/langgraph";
+
+    const threadConfig = { configurable: { thread_id: uuidv4() } };
+
+    const inputs = [
+      // 1st round of conversation
+      {
+        messages: [
+          { role: "user", content: "i wanna go somewhere warm in the caribbean" }
+        ]
+      },
+      // Since we're using `interrupt`, we'll need to resume using the Command primitive.
+      // 2nd round of conversation
+      new Command({
+        resume: "could you recommend a nice hotel in one of the areas and tell me which area it is."
+      }),
+      // 3rd round of conversation
+      new Command({
+        resume: "i like the first one. could you recommend something to do near the hotel?"
+      }),
+    ];
+
+    for (const [idx, userInput] of inputs.entries()) {
+      console.log();
+      console.log(`--- Conversation Turn ${idx + 1} ---`);
+      console.log();
+      console.log(`User: ${JSON.stringify(userInput)}`);
+      console.log();
+      
+      for await (const update of await graph.stream(
+        userInput,
+        { ...threadConfig, streamMode: "updates" }
+      )) {
+        for (const [nodeId, value] of Object.entries(update)) {
+          if (value?.messages?.length) {
+            const lastMessage = value.messages.at(-1);
+            if (lastMessage?.getType?.() === "ai") {
+              console.log(`${nodeId}: ${lastMessage.content}`);
+            }
+          }
+        }
+      }
+    }
+    ```
+    
+    ```
+    --- Conversation Turn 1 ---
+    
+    User: {"messages":[{"role":"user","content":"i wanna go somewhere warm in the caribbean"}]}
+    
+    travel_advisor: Based on the recommendations, Aruba would be an excellent choice for your Caribbean getaway! Aruba is known as "One Happy Island" and offers:
+    - Year-round warm weather with consistent temperatures around 82°F (28°C)
+    - Beautiful white sand beaches like Eagle Beach and Palm Beach
+    - Clear turquoise waters perfect for swimming and snorkeling
+    - Minimal rainfall and location outside the hurricane belt
+    - A blend of Caribbean and Dutch culture
+    - Great dining options and nightlife
+    - Various water sports and activities
+    
+    Would you like me to get some specific hotel recommendations in Aruba for your stay? I can transfer you to our hotel advisor who can help with accommodations.
+    
+    --- Conversation Turn 2 ---
+    
+    User: Command { resume: 'could you recommend a nice hotel in one of the areas and tell me which area it is.' }
+    
+    hotel_advisor: Based on the recommendations, I can suggest two excellent options:
+    
+    1. The Ritz-Carlton, Aruba - Located in Palm Beach
+    - This luxury resort is situated in the vibrant Palm Beach area
+    - Known for its exceptional service and amenities
+    - Perfect if you want to be close to dining, shopping, and entertainment
+    - Features multiple restaurants, a casino, and a world-class spa
+    - Located on a pristine stretch of Palm Beach
+    
+    2. Bucuti & Tara Beach Resort - Located in Eagle Beach
+    - An adults-only boutique resort on Eagle Beach
+    - Known for being more intimate and peaceful
+    - Award-winning for its sustainability practices
+    - Perfect for a romantic getaway or peaceful vacation
+    - Located on one of the most beautiful beaches in the Caribbean
+    
+    Would you like more specific information about either of these properties or their locations?
+    
+    --- Conversation Turn 3 ---
+    
+    User: Command { resume: 'i like the first one. could you recommend something to do near the hotel?' }
+    
+    travel_advisor: Near the Ritz-Carlton in Palm Beach, here are some highly recommended activities:
+    
+    1. Visit the Palm Beach Plaza Mall - Just a short walk from the hotel, featuring shopping, dining, and entertainment
+    2. Try your luck at the Stellaris Casino - It's right in the Ritz-Carlton
+    3. Take a sunset sailing cruise - Many depart from the nearby pier
+    4. Visit the California Lighthouse - A scenic landmark just north of Palm Beach
+    5. Enjoy water sports at Palm Beach:
+       - Jet skiing
+       - Parasailing
+       - Snorkeling
+       - Stand-up paddleboarding
+    
+    Would you like more specific information about any of these activities or would you like to know about other options in the area?
+    ```
+    :::
 
 ## Prebuilt implementations
 
 LangGraph comes with prebuilt implementations of two of the most popular multi-agent architectures:
 
+:::python
 - [supervisor](../agents/multi-agent.md#supervisor) — individual agents are coordinated by a central supervisor agent. The supervisor controls all communication flow and task delegation, making decisions about which agent to invoke based on the current context and task requirements. You can use [`langgraph-supervisor`](https://github.com/langchain-ai/langgraph-supervisor-py) library to create a supervisor multi-agent systems.
-- [swarm](../agents/multi-agent.md#supervisor) — agents dynamically hand off control to one another based on their specializations. The system remembers which agent was last active, ensuring that on subsequent interactions, the conversation resumes with that agent. You can use [`langgraph-swarm`](https://github.com/langchain-ai/langgraph-swarm-py) library to create a swarm multi-agent systems. 
+- [swarm](../agents/multi-agent.md#supervisor) — agents dynamically hand off control to one another based on their specializations. The system remembers which agent was last active, ensuring that on subsequent interactions, the conversation resumes with that agent. You can use [`langgraph-swarm`](https://github.com/langchain-ai/langgraph-swarm-py) library to create a swarm multi-agent systems.
+:::
+
+:::js
+- [supervisor](../agents/multi-agent.md#supervisor) — individual agents are coordinated by a central supervisor agent. The supervisor controls all communication flow and task delegation, making decisions about which agent to invoke based on the current context and task requirements. You can use [`langgraph-supervisor`](https://github.com/langchain-ai/langgraph-supervisor-js) library to create a supervisor multi-agent systems.
+- [swarm](../agents/multi-agent.md#supervisor) — agents dynamically hand off control to one another based on their specializations. The system remembers which agent was last active, ensuring that on subsequent interactions, the conversation resumes with that agent. You can use [`langgraph-swarm`](https://github.com/langchain-ai/langgraph-swarm-js) library to create a swarm multi-agent systems.
+:::

docs/docs/how-tos/subgraph.md

@@ -9,11 +9,20 @@ When adding subgraphs, you need to define how the parent graph and the subgraph
 
 ## Setup
 
+:::python
 ```bash
 pip install -U langgraph
 ```
+:::
+
+:::js
+```bash
+npm install @langchain/langgraph
+```
+:::
 
 !!! tip "Set up LangSmith for LangGraph development"
+
     Sign up for [LangSmith](https://smith.langchain.com) to quickly spot issues and improve the performance of your LangGraph projects. LangSmith lets you use trace data to debug, test, and monitor your LLM apps built with LangGraph — read more about how to get started [here](https://docs.smith.langchain.com).
 
 ## Shared state schemas
@@ -22,6 +31,7 @@ A common case is for the parent graph and subgraph to communicate over a shared
 
 If your subgraph shares state keys with the parent graph, you can follow these steps to add it to your graph:
 
+:::python
 1. Define the subgraph workflow (`subgraph_builder` in the example below) and compile it
 2. Pass compiled subgraph to the `.add_node` method when defining the parent graph workflow
 
@@ -49,9 +59,41 @@ builder.add_node("node_1", subgraph)
 builder.add_edge(START, "node_1")
 graph = builder.compile()
 ```
+:::
+
+:::js
+1. Define the subgraph workflow (`subgraphBuilder` in the example below) and compile it
+2. Pass compiled subgraph to the `.addNode` method when defining the parent graph workflow
+
+```typescript
+import { StateGraph, START } from "@langchain/langgraph";
+import { z } from "zod";
+
+const State = z.object({
+  foo: z.string(),
+});
+
+// Subgraph
+const subgraphBuilder = new StateGraph(State)
+  .addNode("subgraphNode1", (state) => {
+    return { foo: "hi! " + state.foo };
+  })
+  .addEdge(START, "subgraphNode1");
+
+const subgraph = subgraphBuilder.compile();
+
+// Parent graph
+const builder = new StateGraph(State)
+  .addNode("node1", subgraph)
+  .addEdge(START, "node1");
+
+const graph = builder.compile();
+```
+:::
 
 ??? example "Full example: shared state schemas"
 
+    :::python
     ```python
     from typing_extensions import TypedDict
     from langgraph.graph.state import StateGraph, START
@@ -101,6 +143,61 @@ graph = builder.compile()
     {'node_1': {'foo': 'hi! foo'}}
     {'node_2': {'foo': 'hi! foobar'}}
     ```
+    :::
+
+    :::js
+    ```typescript
+    import { StateGraph, START } from "@langchain/langgraph";
+    import { z } from "zod";
+
+    // Define subgraph
+    const SubgraphState = z.object({
+      foo: z.string(),  // (1)! 
+      bar: z.string(),  // (2)!
+    });
+    
+    const subgraphBuilder = new StateGraph(SubgraphState)
+      .addNode("subgraphNode1", (state) => {
+        return { bar: "bar" };
+      })
+      .addNode("subgraphNode2", (state) => {
+        // note that this node is using a state key ('bar') that is only available in the subgraph
+        // and is sending update on the shared state key ('foo')
+        return { foo: state.foo + state.bar };
+      })
+      .addEdge(START, "subgraphNode1")
+      .addEdge("subgraphNode1", "subgraphNode2");
+    
+    const subgraph = subgraphBuilder.compile();
+    
+    // Define parent graph
+    const ParentState = z.object({
+      foo: z.string(),
+    });
+    
+    const builder = new StateGraph(ParentState)
+      .addNode("node1", (state) => {
+        return { foo: "hi! " + state.foo };
+      })
+      .addNode("node2", subgraph)
+      .addEdge(START, "node1")
+      .addEdge("node1", "node2");
+    
+    const graph = builder.compile();
+    
+    for await (const chunk of await graph.stream({ foo: "foo" })) {
+      console.log(chunk);
+    }
+    ```
+
+    3. This key is shared with the parent graph state
+    4. This key is private to the `SubgraphState` and is not visible to the parent graph
+    
+    ```
+    { node1: { foo: 'hi! foo' } }
+    { node2: { foo: 'hi! foobar' } }
+    ```
+    :::
 
 ## Different state schemas
 
@@ -108,6 +205,7 @@ For more complex systems you might want to define subgraphs that have a **comple
 
 If that's the case for your application, you need to define a node **function that invokes the subgraph**. This function needs to transform the input (parent) state to the subgraph state before invoking the subgraph, and transform the results back to the parent state before returning the state update from the node.
 
+:::python
 ```python
 from typing_extensions import TypedDict
 from langgraph.graph.state import StateGraph, START
@@ -142,9 +240,48 @@ graph = builder.compile()
 
 1. Transform the state to the subgraph state
 2. Transform response back to the parent state
+:::
+
+:::js
+```typescript
+import { StateGraph, START } from "@langchain/langgraph";
+import { z } from "zod";
+
+const SubgraphState = z.object({
+  bar: z.string(),
+});
+
+// Subgraph
+const subgraphBuilder = new StateGraph(SubgraphState)
+  .addNode("subgraphNode1", (state) => {
+    return { bar: "hi! " + state.bar };
+  })
+  .addEdge(START, "subgraphNode1");
+
+const subgraph = subgraphBuilder.compile();
+
+// Parent graph
+const State = z.object({
+  foo: z.string(),
+});
+
+const builder = new StateGraph(State)
+  .addNode("node1", async (state) => {
+    const subgraphOutput = await subgraph.invoke({ bar: state.foo }); // (1)!
+    return { foo: subgraphOutput.bar }; // (2)!
+  })
+  .addEdge(START, "node1");
+
+const graph = builder.compile();
+```
+
+1. Transform the state to the subgraph state
+2. Transform response back to the parent state
+:::
 
 ??? example "Full example: different state schemas"
 
+    :::python
     ```python
     from typing_extensions import TypedDict
     from langgraph.graph.state import StateGraph, START
@@ -200,11 +337,74 @@ graph = builder.compile()
     (('node_2:9c36dd0f-151a-cb42-cbad-fa2f851f9ab7',), {'grandchild_2': {'bar': 'hi! foobaz'}})
     ((), {'node_2': {'foo': 'hi! foobaz'}})
     ```
+    :::
+
+    :::js
+    ```typescript
+    import { StateGraph, START } from "@langchain/langgraph";
+    import { z } from "zod";
+
+    // Define subgraph
+    const SubgraphState = z.object({
+      // note that none of these keys are shared with the parent graph state
+      bar: z.string(),
+      baz: z.string(),
+    });
+    
+    const subgraphBuilder = new StateGraph(SubgraphState)
+      .addNode("subgraphNode1", (state) => {
+        return { baz: "baz" };
+      })
+      .addNode("subgraphNode2", (state) => {
+        return { bar: state.bar + state.baz };
+      })
+      .addEdge(START, "subgraphNode1")
+      .addEdge("subgraphNode1", "subgraphNode2");
+    
+    const subgraph = subgraphBuilder.compile();
+    
+    // Define parent graph
+    const ParentState = z.object({
+      foo: z.string(),
+    });
+    
+    const builder = new StateGraph(ParentState)
+      .addNode("node1", (state) => {
+        return { foo: "hi! " + state.foo };
+      })
+      .addNode("node2", async (state) => {
+        const response = await subgraph.invoke({ bar: state.foo }); // (1)!
+        return { foo: response.bar }; // (2)!
+      })
+      .addEdge(START, "node1")
+      .addEdge("node1", "node2");
+    
+    const graph = builder.compile();
+    
+    for await (const chunk of await graph.stream(
+      { foo: "foo" }, 
+      { subgraphs: true }
+    )) {
+      console.log(chunk);
+    }
+    ```
+
+    3. Transform the state to the subgraph state
+    4. Transform response back to the parent state
+
+    ```
+    [[], { node1: { foo: 'hi! foo' } }]
+    [['node2:9c36dd0f-151a-cb42-cbad-fa2f851f9ab7'], { subgraphNode1: { baz: 'baz' } }]
+    [['node2:9c36dd0f-151a-cb42-cbad-fa2f851f9ab7'], { subgraphNode2: { bar: 'hi! foobaz' } }]
+    [[], { node2: { foo: 'hi! foobaz' } }]
+    ```
+    :::
 
 ??? example "Full example: different state schemas (two levels of subgraphs)"
 
     This is an example with two levels of subgraphs: parent -> child -> grandchild.
 
+    :::python
     ```python
     # Grandchild graph
     from typing_extensions import TypedDict
@@ -288,14 +488,102 @@ graph = builder.compile()
     ((), {'child': {'my_key': 'hi Bob, how are you today?'}})
     ((), {'parent_2': {'my_key': 'hi Bob, how are you today? bye!'}})
     ```
+    :::
+
+    :::js
+    ```typescript
+    import { StateGraph, START, END } from "@langchain/langgraph";
+    import { z } from "zod";
+
+    // Grandchild graph
+    const GrandChildState = z.object({
+      myGrandchildKey: z.string(),
+    });
+    
+    const grandchild = new StateGraph(GrandChildState)
+      .addNode("grandchild1", (state) => {
+        // NOTE: child or parent keys will not be accessible here
+        return { myGrandchildKey: state.myGrandchildKey + ", how are you" };
+      })
+      .addEdge(START, "grandchild1")
+      .addEdge("grandchild1", END);
+    
+    const grandchildGraph = grandchild.compile();
+    
+    // Child graph
+    const ChildState = z.object({
+      myChildKey: z.string(),
+    });
+    
+    const child = new StateGraph(ChildState)
+      .addNode("child1", async (state) => {
+        // NOTE: parent or grandchild keys won't be accessible here
+        const grandchildGraphInput = { myGrandchildKey: state.myChildKey }; // (1)!
+        const grandchildGraphOutput = await grandchildGraph.invoke(grandchildGraphInput);
+        return { myChildKey: grandchildGraphOutput.myGrandchildKey + " today?" }; // (2)!
+      }) // (3)!
+      .addEdge(START, "child1")
+      .addEdge("child1", END);
+    
+    const childGraph = child.compile();
+    
+    // Parent graph
+    const ParentState = z.object({
+      myKey: z.string(),
+    });
+    
+    const parent = new StateGraph(ParentState)
+      .addNode("parent1", (state) => {
+        // NOTE: child or grandchild keys won't be accessible here
+        return { myKey: "hi " + state.myKey };
+      })
+      .addNode("child", async (state) => {
+        const childGraphInput = { myChildKey: state.myKey }; // (4)!
+        const childGraphOutput = await childGraph.invoke(childGraphInput);
+        return { myKey: childGraphOutput.myChildKey }; // (5)!
+      }) // (6)!
+      .addNode("parent2", (state) => {
+        return { myKey: state.myKey + " bye!" };
+      })
+      .addEdge(START, "parent1")
+      .addEdge("parent1", "child")
+      .addEdge("child", "parent2")
+      .addEdge("parent2", END);
+    
+    const parentGraph = parent.compile();
+    
+    for await (const chunk of await parentGraph.stream(
+      { myKey: "Bob" }, 
+      { subgraphs: true }
+    )) {
+      console.log(chunk);
+    }
+    ```
+
+    7. We're transforming the state from the child state channels (`myChildKey`) to the grandchild state channels (`myGrandchildKey`)
+    8. We're transforming the state from the grandchild state channels (`myGrandchildKey`) back to the child state channels (`myChildKey`)
+    9. We're passing a function here instead of just compiled graph (`grandchildGraph`)
+    10. We're transforming the state from the parent state channels (`myKey`) to the child state channels (`myChildKey`)
+    11. We're transforming the state from the child state channels (`myChildKey`) back to the parent state channels (`myKey`)
+    12. We're passing a function here instead of just a compiled graph (`childGraph`)
+
+    ```
+    [[], { parent1: { myKey: 'hi Bob' } }]
+    [['child:2e26e9ce-602f-862c-aa66-1ea5a4655e3b', 'child1:781bb3b1-3971-84ce-810b-acf819a03f9c'], { grandchild1: { myGrandchildKey: 'hi Bob, how are you' } }]
+    [['child:2e26e9ce-602f-862c-aa66-1ea5a4655e3b'], { child1: { myChildKey: 'hi Bob, how are you today?' } }]
+    [[], { child: { myKey: 'hi Bob, how are you today?' } }]
+    [[], { parent2: { myKey: 'hi Bob, how are you today? bye!' } }]
+    ```
+    :::
 
 ## Add persistence 
 
 You only need to **provide the checkpointer when compiling the parent graph**. LangGraph will automatically propagate the checkpointer to the child subgraphs.
 
+:::python
 ```python
 from langgraph.graph import START, StateGraph
-from langgraph.checkpoint.memory import InMemorySaver
+from langgraph.checkpoint.memory import MemorySaver
 from typing_extensions import TypedDict
 
 class State(TypedDict):
@@ -317,20 +605,66 @@ builder = StateGraph(State)
 builder.add_node("node_1", subgraph)
 builder.add_edge(START, "node_1")
 
-checkpointer = InMemorySaver()
+checkpointer = MemorySaver()
 graph = builder.compile(checkpointer=checkpointer)
 ```    
+:::
 
-If you want the subgraph to **have its own memory**, you can compile it `with checkpointer=True`. This is useful in [multi-agent](../concepts/multi_agent.md) systems, if you want agents to keep track of their internal message histories:
+:::js
+```typescript
+import { StateGraph, START, MemorySaver } from "@langchain/langgraph";
+import { z } from "zod";
 
+const State = z.object({
+  foo: z.string(),
+});
+
+// Subgraph
+const subgraphBuilder = new StateGraph(State)
+  .addNode("subgraphNode1", (state) => {
+    return { foo: state.foo + "bar" };
+  })
+  .addEdge(START, "subgraphNode1");
+
+const subgraph = subgraphBuilder.compile();
+
+// Parent graph
+const builder = new StateGraph(State)
+  .addNode("node1", subgraph)
+  .addEdge(START, "node1");
+
+const checkpointer = new MemorySaver();
+const graph = builder.compile({ checkpointer });
+```    
+:::
+
+If you want the subgraph to **have its own memory**, you can compile it with the appropriate checkpointer option. This is useful in [multi-agent](../concepts/multi_agent.md) systems, if you want agents to keep track of their internal message histories:
+
+:::python
 ```python
 subgraph_builder = StateGraph(...)
 subgraph = subgraph_builder.compile(checkpointer=True)
 ```
+:::
+
+:::js
+```typescript
+const subgraphBuilder = new StateGraph(...)
+const subgraph = subgraphBuilder.compile({ checkpointer: true });
+```
+:::
 
 ## View subgraph state
 
-When you enable [persistence](../concepts/persistence.md), you can [inspect the graph state](../concepts/persistence.md#checkpoints) (checkpoint) via `graph.get_state(config)`. To view the subgraph state, you can use `graph.get_state(config, subgraphs=True)`.
+When you enable [persistence](../concepts/persistence.md), you can [inspect the graph state](../concepts/persistence.md#checkpoints) (checkpoint) via the appropriate method. To view the subgraph state, you can use the subgraphs option.
+
+:::python
+You can inspect the graph state via `graph.get_state(config)`. To view the subgraph state, you can use `graph.get_state(config, subgraphs=True)`.
+:::
+
+:::js
+You can inspect the graph state via `graph.getState(config)`. To view the subgraph state, you can use `graph.getState(config, { subgraphs: true })`.
+:::
 
 !!! important "Available **only** when interrupted"
 
@@ -338,9 +672,10 @@ When you enable [persistence](../concepts/persistence.md), you can [inspect the
 
 ??? example "View interrupted subgraph state"
 
+    :::python
     ```python
     from langgraph.graph import START, StateGraph
-    from langgraph.checkpoint.memory import InMemorySaver
+    from langgraph.checkpoint.memory import MemorySaver
     from langgraph.types import interrupt, Command
     from typing_extensions import TypedDict
     
@@ -365,7 +700,7 @@ When you enable [persistence](../concepts/persistence.md), you can [inspect the
     builder.add_node("node_1", subgraph)
     builder.add_edge(START, "node_1")
     
-    checkpointer = InMemorySaver()
+    checkpointer = MemorySaver()
     graph = builder.compile(checkpointer=checkpointer)
     
     config = {"configurable": {"thread_id": "1"}}
@@ -379,11 +714,53 @@ When you enable [persistence](../concepts/persistence.md), you can [inspect the
     ```
     
     1. This will be available only when the subgraph is interrupted. Once you resume the graph, you won't be able to access the subgraph state.
+    :::
+
+    :::js
+    ```typescript
+    import { StateGraph, START, MemorySaver, interrupt, Command } from "@langchain/langgraph";
+    import { z } from "zod";
+    
+    const State = z.object({
+      foo: z.string(),
+    });
+    
+    // Subgraph
+    const subgraphBuilder = new StateGraph(State)
+      .addNode("subgraphNode1", (state) => {
+        const value = interrupt("Provide value:");
+        return { foo: state.foo + value };
+      })
+      .addEdge(START, "subgraphNode1");
+    
+    const subgraph = subgraphBuilder.compile();
+    
+    // Parent graph
+    const builder = new StateGraph(State)
+      .addNode("node1", subgraph)
+      .addEdge(START, "node1");
+    
+    const checkpointer = new MemorySaver();
+    const graph = builder.compile({ checkpointer });
+    
+    const config = { configurable: { thread_id: "1" } };
+    
+    await graph.invoke({ foo: "" }, config);
+    const parentState = await graph.getState(config);
+    const subgraphState = (await graph.getState(config, { subgraphs: true })).tasks[0].state; // (1)!
+    
+    // resume the subgraph
+    await graph.invoke(new Command({ resume: "bar" }), config);
+    ```
+    
+    2. This will be available only when the subgraph is interrupted. Once you resume the graph, you won't be able to access the subgraph state.
+    :::
 
 ## Stream subgraph outputs
 
-To include outputs from subgraphs in the streamed outputs, you can set `subgraphs=True` in the `.stream()` method of the parent graph. This will stream outputs from both the parent graph and any subgraphs.
+To include outputs from subgraphs in the streamed outputs, you can set the subgraphs option in the stream method of the parent graph. This will stream outputs from both the parent graph and any subgraphs.
 
+:::python
 ```python
 for chunk in graph.stream(
     {"foo": "foo"},
@@ -394,9 +771,27 @@ for chunk in graph.stream(
 ```
 
 1. Set `subgraphs=True` to stream outputs from subgraphs.
+:::
+
+:::js
+```typescript
+for await (const chunk of await graph.stream(
+  { foo: "foo" },
+  {
+    subgraphs: true, // (1)!
+    streamMode: "updates",
+  }
+)) {
+  console.log(chunk);
+}
+```
+
+1. Set `subgraphs: true` to stream outputs from subgraphs.
+:::
 
 ??? example "Stream from subgraphs"
 
+    :::python
     ```python
     from typing_extensions import TypedDict
     from langgraph.graph.state import StateGraph, START
@@ -450,4 +845,66 @@ for chunk in graph.stream(
     (('node_2:e58e5673-a661-ebb0-70d4-e298a7fc28b7',), {'subgraph_node_1': {'bar': 'bar'}})
     (('node_2:e58e5673-a661-ebb0-70d4-e298a7fc28b7',), {'subgraph_node_2': {'foo': 'hi! foobar'}})
     ((), {'node_2': {'foo': 'hi! foobar'}})
-    
+    ```
+    :::
+
+    :::js
+    ```typescript
+    import { StateGraph, START } from "@langchain/langgraph";
+    import { z } from "zod";
+
+    // Define subgraph
+    const SubgraphState = z.object({
+      foo: z.string(),
+      bar: z.string(),
+    });
+    
+    const subgraphBuilder = new StateGraph(SubgraphState)
+      .addNode("subgraphNode1", (state) => {
+        return { bar: "bar" };
+      })
+      .addNode("subgraphNode2", (state) => {
+        // note that this node is using a state key ('bar') that is only available in the subgraph
+        // and is sending update on the shared state key ('foo')
+        return { foo: state.foo + state.bar };
+      })
+      .addEdge(START, "subgraphNode1")
+      .addEdge("subgraphNode1", "subgraphNode2");
+    
+    const subgraph = subgraphBuilder.compile();
+    
+    // Define parent graph
+    const ParentState = z.object({
+      foo: z.string(),
+    });
+    
+    const builder = new StateGraph(ParentState)
+      .addNode("node1", (state) => {
+        return { foo: "hi! " + state.foo };
+      })
+      .addNode("node2", subgraph)
+      .addEdge(START, "node1")
+      .addEdge("node1", "node2");
+    
+    const graph = builder.compile();
+
+    for await (const chunk of await graph.stream(
+      { foo: "foo" },
+      {
+        streamMode: "updates",
+        subgraphs: true, // (1)!
+      }
+    )) {
+      console.log(chunk);
+    }
+    ```
+  
+    2. Set `subgraphs: true` to stream outputs from subgraphs.
+
+    ```
+    [[], { node1: { foo: 'hi! foo' } }]
+    [['node2:e58e5673-a661-ebb0-70d4-e298a7fc28b7'], { subgraphNode1: { bar: 'bar' } }]
+    [['node2:e58e5673-a661-ebb0-70d4-e298a7fc28b7'], { subgraphNode2: { foo: 'hi! foobar' } }]
+    [[], { node2: { foo: 'hi! foobar' } }]
+    ```
+    :::

libs/prebuilt/Makefile

@@ -30,6 +30,9 @@ test_watch:
 	make stop-services; \
 	exit $$EXIT_CODE
 
+snapshot_upate:
+	LANGGRAPH_TEST_FAST=1 uv run pytest --snapshot-update $(TEST)
+
 ######################
 # LINTING AND FORMATTING
 ######################

libs/prebuilt/langgraph/prebuilt/tool_node.py

@@ -344,18 +344,18 @@ class ToolNode(RunnableCallable):
         self.handle_tool_errors = handle_tool_errors
         self.messages_key = messages_key
         for tool_ in tools:
-            if issubclass(tool_, BaseModel):
+            if inspect.isclass(tool_) and issubclass(tool_, BaseModel):
+                # Handle Pydantic model classes as structured output tools
                 self.tools_by_name[tool_.__name__] = tool_
                 self.tool_to_state_args[tool_.__name__] = {}
                 self.tool_to_store_arg[tool_.__name__] = None
                 self.structured_output_tools.append(tool_.__name__)
-                continue
-            elif not isinstance(tool_, BaseTool):
-                tool_ = create_tool(tool_)
-
-            self.tools_by_name[tool_.name] = tool_
-            self.tool_to_state_args[tool_.name] = _get_state_args(tool_)
-            self.tool_to_store_arg[tool_.name] = _get_store_arg(tool_)
+            else:
+                if not isinstance(tool_, BaseTool):
+                    tool_ = create_tool(tool_)
+                self.tools_by_name[tool_.name] = tool_
+                self.tool_to_state_args[tool_.name] = _get_state_args(tool_)
+                self.tool_to_store_arg[tool_.name] = _get_store_arg(tool_)
 
     def _func(
         self,
@@ -398,7 +398,7 @@ class ToolNode(RunnableCallable):
 
     def _combine_tool_outputs(
         self,
-        outputs: list[ToolMessage],
+        outputs: list[Union[ToolMessage, Command]],
         input_type: Literal["list", "dict", "tool_calls"],
     ) -> list[Union[Command, list[ToolMessage], dict[str, list[ToolMessage]]]]:
         # preserve existing behavior for non-command tool outputs for backwards
@@ -445,26 +445,28 @@ class ToolNode(RunnableCallable):
         call: ToolCall,
         input_type: Literal["list", "dict", "tool_calls"],
         config: RunnableConfig,
-    ) -> ToolMessage | Command:
+    ) -> Union[ToolMessage, Command]:
         """Run a single tool call synchronously."""
         if invalid_tool_message := self._validate_tool_call(call):
             return invalid_tool_message
+
+        # Handle structured output tools
+        if call["name"] in self.structured_output_tools:
+            response_schema = self.tools_by_name[call["name"]]
+            return Command(
+                update={
+                    "messages": [
+                        ToolMessage(
+                            content=msg_content_output(call["args"]),
+                            name=call["name"],
+                            tool_call_id=call["id"],
+                        )
+                    ],
+                    "structured_response": response_schema(**call["args"]),
+                }
+            )
+
         try:
-            if call["name"] in self.structured_output_tools:
-                response_schema = self.tools_by_name[call["name"]]
-                return Command(
-                    update={
-                        "messages": [
-                            ToolMessage(
-                                content="structured output generated",
-                                name="structured_output",
-                                tool_call_id=call["id"],
-                                status="success",
-                            ),
-                        ],
-                        "structured_response": response_schema(**call["args"]),
-                    }
-                )
             call_args = {**call, **{"type": "tool_call"}}
             response = self.tools_by_name[call["name"]].invoke(call_args, config)
 
@@ -516,11 +518,27 @@ class ToolNode(RunnableCallable):
         call: ToolCall,
         input_type: Literal["list", "dict", "tool_calls"],
         config: RunnableConfig,
-    ) -> ToolMessage:
+    ) -> Union[ToolMessage, Command]:
         """Run a single tool call asynchronously."""
         if invalid_tool_message := self._validate_tool_call(call):
             return invalid_tool_message
 
+        # Handle structured output tools
+        if call["name"] in self.structured_output_tools:
+            response_schema = self.tools_by_name[call["name"]]
+            return Command(
+                update={
+                    "messages": [
+                        ToolMessage(
+                            content=msg_content_output(call["args"]),
+                            name=call["name"],
+                            tool_call_id=call["id"],
+                        )
+                    ],
+                    "structured_response": response_schema(**call["args"]),
+                }
+            )
+
         try:
             call_args = {**call, **{"type": "tool_call"}}
             response = await self.tools_by_name[call["name"]].ainvoke(call_args, config)

libs/prebuilt/tests/__snapshots__/test_react_agent_graph.ambr

@@ -171,3 +171,191 @@
   
   '''
 # ---
+# name: test_react_agent_graph_structure_with_individual_nodes[no_response_format-no_post_hook-no_pre_hook-no_tools]
+  '''
+  graph TD;
+  	__start__ --> agent;
+  	agent --> __end__;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[no_response_format-no_post_hook-no_pre_hook-two_tools]
+  '''
+  graph TD;
+  	__start__ --> agent;
+  	agent -.-> __end__;
+  	agent -.-> tool;
+  	agent -.-> tool2;
+  	tool --> agent;
+  	tool2 --> agent;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[no_response_format-no_post_hook-with_pre_hook-no_tools]
+  '''
+  graph TD;
+  	__start__ --> pre_model_hook;
+  	pre_model_hook --> agent;
+  	agent --> __end__;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[no_response_format-no_post_hook-with_pre_hook-two_tools]
+  '''
+  graph TD;
+  	__start__ --> pre_model_hook;
+  	agent -.-> __end__;
+  	agent -.-> tool;
+  	agent -.-> tool2;
+  	pre_model_hook --> agent;
+  	tool --> pre_model_hook;
+  	tool2 --> pre_model_hook;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[no_response_format-with_post_hook-no_pre_hook-no_tools]
+  '''
+  graph TD;
+  	__start__ --> agent;
+  	agent --> post_model_hook;
+  	post_model_hook --> __end__;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[no_response_format-with_post_hook-no_pre_hook-two_tools]
+  '''
+  graph TD;
+  	__start__ --> agent;
+  	agent --> post_model_hook;
+  	post_model_hook -.-> __end__;
+  	post_model_hook -.-> agent;
+  	post_model_hook -.-> tool;
+  	post_model_hook -.-> tool2;
+  	tool --> agent;
+  	tool2 --> agent;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[no_response_format-with_post_hook-with_pre_hook-no_tools]
+  '''
+  graph TD;
+  	__start__ --> pre_model_hook;
+  	agent --> post_model_hook;
+  	pre_model_hook --> agent;
+  	post_model_hook --> __end__;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[no_response_format-with_post_hook-with_pre_hook-two_tools]
+  '''
+  graph TD;
+  	__start__ --> pre_model_hook;
+  	agent --> post_model_hook;
+  	post_model_hook -.-> __end__;
+  	post_model_hook -.-> pre_model_hook;
+  	post_model_hook -.-> tool;
+  	post_model_hook -.-> tool2;
+  	pre_model_hook --> agent;
+  	tool --> pre_model_hook;
+  	tool2 --> pre_model_hook;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[with_response_format-no_post_hook-no_pre_hook-no_tools]
+  '''
+  graph TD;
+  	__start__ --> agent;
+  	agent --> generate_structured_response;
+  	generate_structured_response --> __end__;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[with_response_format-no_post_hook-no_pre_hook-two_tools]
+  '''
+  graph TD;
+  	__start__ --> agent;
+  	agent -.-> generate_structured_response;
+  	agent -.-> tool;
+  	agent -.-> tool2;
+  	tool --> agent;
+  	tool2 --> agent;
+  	generate_structured_response --> __end__;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[with_response_format-no_post_hook-with_pre_hook-no_tools]
+  '''
+  graph TD;
+  	__start__ --> pre_model_hook;
+  	agent --> generate_structured_response;
+  	pre_model_hook --> agent;
+  	generate_structured_response --> __end__;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[with_response_format-no_post_hook-with_pre_hook-two_tools]
+  '''
+  graph TD;
+  	__start__ --> pre_model_hook;
+  	agent -.-> generate_structured_response;
+  	agent -.-> tool;
+  	agent -.-> tool2;
+  	pre_model_hook --> agent;
+  	tool --> pre_model_hook;
+  	tool2 --> pre_model_hook;
+  	generate_structured_response --> __end__;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[with_response_format-with_post_hook-no_pre_hook-no_tools]
+  '''
+  graph TD;
+  	__start__ --> agent;
+  	agent --> post_model_hook;
+  	post_model_hook --> generate_structured_response;
+  	generate_structured_response --> __end__;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[with_response_format-with_post_hook-no_pre_hook-two_tools]
+  '''
+  graph TD;
+  	__start__ --> agent;
+  	agent --> post_model_hook;
+  	post_model_hook -.-> agent;
+  	post_model_hook -.-> generate_structured_response;
+  	post_model_hook -.-> tool;
+  	post_model_hook -.-> tool2;
+  	tool --> agent;
+  	tool2 --> agent;
+  	generate_structured_response --> __end__;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[with_response_format-with_post_hook-with_pre_hook-no_tools]
+  '''
+  graph TD;
+  	__start__ --> pre_model_hook;
+  	agent --> post_model_hook;
+  	post_model_hook --> generate_structured_response;
+  	pre_model_hook --> agent;
+  	generate_structured_response --> __end__;
+  
+  '''
+# ---
+# name: test_react_agent_graph_structure_with_individual_nodes[with_response_format-with_post_hook-with_pre_hook-two_tools]
+  '''
+  graph TD;
+  	__start__ --> pre_model_hook;
+  	agent --> post_model_hook;
+  	post_model_hook -.-> generate_structured_response;
+  	post_model_hook -.-> pre_model_hook;
+  	post_model_hook -.-> tool;
+  	post_model_hook -.-> tool2;
+  	pre_model_hook --> agent;
+  	tool --> pre_model_hook;
+  	tool2 --> pre_model_hook;
+  	generate_structured_response --> __end__;
+  
+  '''
+# ---

libs/prebuilt/tests/test_react_agent.py

@@ -1,14 +1,9 @@
 import dataclasses
 import inspect
-import json
-from functools import partial
 from typing import (
     Annotated,
-    List,
     Literal,
     Optional,
-    Type,
-    TypeVar,
     Union,
 )
 
@@ -16,7 +11,6 @@ import pytest
 from langchain_core.language_models import BaseChatModel
 from langchain_core.messages import (
     AIMessage,
-    AnyMessage,
     HumanMessage,
     MessageLikeRepresentation,
     RemoveMessage,
@@ -28,17 +22,14 @@ from langchain_core.runnables import RunnableConfig, RunnableLambda
 from langchain_core.tools import InjectedToolCallId, ToolException
 from langchain_core.tools import tool as dec_tool
 from pydantic import BaseModel, Field
-from pydantic.v1 import BaseModel as BaseModelV1
 from typing_extensions import TypedDict
 
 from langgraph.checkpoint.base import BaseCheckpointSaver
-from langgraph.config import get_stream_writer
-from langgraph.graph import START, MessagesState, StateGraph, add_messages
+from langgraph.graph import START, MessagesState, StateGraph
 from langgraph.graph.message import REMOVE_ALL_MESSAGES
 from langgraph.prebuilt import (
     ToolNode,
     create_react_agent,
-    tools_condition,
 )
 from langgraph.prebuilt.chat_agent_executor import (
     AgentState,
@@ -184,7 +175,7 @@ def test_runnable_prompt():
 
 
 @pytest.mark.parametrize("version", REACT_TOOL_CALL_VERSIONS)
-def test_prompt_with_store(version: str):
+def test_prompt_with_store(version: Literal["v1", "v2"]):
     def add(a: int, b: int):
         """Adds a and b"""
         return a + b
@@ -654,124 +645,6 @@ def test_react_agent_parallel_tool_calls(
         assert get_weather_execution_count == 1
 
 
-class _InjectStateSchema(TypedDict):
-    messages: list
-    foo: str
-
-
-class _InjectedStatePydanticSchema(BaseModelV1):
-    messages: list
-    foo: str
-
-
-class _InjectedStatePydanticV2Schema(BaseModel):
-    messages: list
-    foo: str
-
-
-@dataclasses.dataclass
-class _InjectedStateDataclassSchema:
-    messages: list
-    foo: str
-
-
-T = TypeVar("T")
-
-
-@pytest.mark.parametrize(
-    "schema_",
-    [
-        _InjectStateSchema,
-        _InjectedStatePydanticSchema,
-        _InjectedStatePydanticV2Schema,
-        _InjectedStateDataclassSchema,
-    ],
-)
-def test_tool_node_inject_state(schema_: Type[T]) -> None:
-    def tool1(some_val: int, state: Annotated[T, InjectedState]) -> str:
-        """Tool 1 docstring."""
-        if isinstance(state, dict):
-            return state["foo"]
-        else:
-            return getattr(state, "foo")
-
-    def tool2(some_val: int, state: Annotated[T, InjectedState()]) -> str:
-        """Tool 2 docstring."""
-        if isinstance(state, dict):
-            return state["foo"]
-        else:
-            return getattr(state, "foo")
-
-    def tool3(
-        some_val: int,
-        foo: Annotated[str, InjectedState("foo")],
-        msgs: Annotated[List[AnyMessage], InjectedState("messages")],
-    ) -> str:
-        """Tool 1 docstring."""
-        return foo
-
-    def tool4(
-        some_val: int, msgs: Annotated[List[AnyMessage], InjectedState("messages")]
-    ) -> str:
-        """Tool 1 docstring."""
-        return msgs[0].content
-
-    node = ToolNode([tool1, tool2, tool3, tool4])
-    for tool_name in ("tool1", "tool2", "tool3"):
-        tool_call = {
-            "name": tool_name,
-            "args": {"some_val": 1},
-            "id": "some 0",
-            "type": "tool_call",
-        }
-        msg = AIMessage("hi?", tool_calls=[tool_call])
-        result = node.invoke(schema_(**{"messages": [msg], "foo": "bar"}))
-        tool_message = result["messages"][-1]
-        assert tool_message.content == "bar", f"Failed for tool={tool_name}"
-
-        if tool_name == "tool3":
-            failure_input = None
-            try:
-                failure_input = schema_(**{"messages": [msg], "notfoo": "bar"})
-            except Exception:
-                pass
-            if failure_input is not None:
-                with pytest.raises(KeyError):
-                    node.invoke(failure_input)
-
-                with pytest.raises(ValueError):
-                    node.invoke([msg])
-        else:
-            failure_input = None
-            try:
-                failure_input = schema_(**{"messages": [msg], "notfoo": "bar"})
-            except Exception:
-                # We'd get a validation error from pydantic state and wouldn't make it to the node
-                # anyway
-                pass
-            if failure_input is not None:
-                messages_ = node.invoke(failure_input)
-                tool_message = messages_["messages"][-1]
-                assert "KeyError" in tool_message.content
-                tool_message = node.invoke([msg])[-1]
-                assert "KeyError" in tool_message.content
-
-    tool_call = {
-        "name": "tool4",
-        "args": {"some_val": 1},
-        "id": "some 0",
-        "type": "tool_call",
-    }
-    msg = AIMessage("hi?", tool_calls=[tool_call])
-    result = node.invoke(schema_(**{"messages": [msg], "foo": ""}))
-    tool_message = result["messages"][-1]
-    assert tool_message.content == "hi?"
-
-    result = node.invoke([msg])
-    tool_message = result[-1]
-    assert tool_message.content == "hi?"
-
-
 class AgentStateExtraKey(AgentState):
     foo: int
 
@@ -780,14 +653,24 @@ class AgentStateExtraKeyPydantic(AgentStatePydantic):
     foo: int
 
 
-@pytest.mark.parametrize("version", REACT_TOOL_CALL_VERSIONS)
+@pytest.mark.parametrize("version", ["v1", "v2"])
 @pytest.mark.parametrize(
     "state_schema", [AgentStateExtraKey, AgentStateExtraKeyPydantic]
 )
+@pytest.mark.parametrize(
+    "use_individual_tool_nodes",
+    [False, True],
+    ids=["single_tool_node", "node_per_tool"],
+)
 def test_create_react_agent_inject_vars(
-    version: Literal["v1", "v2"], state_schema: StateSchemaType
+    version: Literal["v1", "v2"],
+    state_schema: StateSchemaType,
+    use_individual_tool_nodes: bool,
 ) -> None:
     """Test that the agent can inject state and store into tool functions."""
+    if version == "v1" and use_individual_tool_nodes:
+        pytest.skip("v1 does not support individual tool nodes")
+
     store = InMemoryStore()
     namespace = ("test",)
     store.put(namespace, "test_key", {"bar": 3})
@@ -826,6 +709,7 @@ def test_create_react_agent_inject_vars(
         state_schema=state_schema,
         store=store,
         version=version,
+        use_individual_tool_nodes=use_individual_tool_nodes,
     )
     result = agent.invoke({"messages": [{"role": "user", "content": "hi"}], "foo": 2})
     assert result["messages"] == [
@@ -837,137 +721,18 @@ def test_create_react_agent_inject_vars(
     assert result["foo"] == 2
 
 
-def test_tool_node_inject_store() -> None:
-    store = InMemoryStore()
-    namespace = ("test",)
-
-    def tool1(some_val: int, store: Annotated[BaseStore, InjectedStore()]) -> str:
-        """Tool 1 docstring."""
-        store_val = store.get(namespace, "test_key").value["foo"]
-        return f"Some val: {some_val}, store val: {store_val}"
-
-    def tool2(some_val: int, store: Annotated[BaseStore, InjectedStore()]) -> str:
-        """Tool 2 docstring."""
-        store_val = store.get(namespace, "test_key").value["foo"]
-        return f"Some val: {some_val}, store val: {store_val}"
-
-    def tool3(
-        some_val: int,
-        bar: Annotated[str, InjectedState("bar")],
-        store: Annotated[BaseStore, InjectedStore()],
-    ) -> str:
-        """Tool 3 docstring."""
-        store_val = store.get(namespace, "test_key").value["foo"]
-        return f"Some val: {some_val}, store val: {store_val}, state val: {bar}"
-
-    node = ToolNode([tool1, tool2, tool3], handle_tool_errors=True)
-    store.put(namespace, "test_key", {"foo": "bar"})
-
-    class State(MessagesState):
-        bar: str
-
-    builder = StateGraph(State)
-    builder.add_node("tools", node)
-    builder.add_edge(START, "tools")
-    graph = builder.compile(store=store)
-
-    for tool_name in ("tool1", "tool2"):
-        tool_call = {
-            "name": tool_name,
-            "args": {"some_val": 1},
-            "id": "some 0",
-            "type": "tool_call",
-        }
-        msg = AIMessage("hi?", tool_calls=[tool_call])
-        node_result = node.invoke({"messages": [msg]}, store=store)
-        graph_result = graph.invoke({"messages": [msg]})
-        for result in (node_result, graph_result):
-            result["messages"][-1]
-            tool_message = result["messages"][-1]
-            assert tool_message.content == "Some val: 1, store val: bar", (
-                f"Failed for tool={tool_name}"
-            )
-
-    tool_call = {
-        "name": "tool3",
-        "args": {"some_val": 1},
-        "id": "some 0",
-        "type": "tool_call",
-    }
-    msg = AIMessage("hi?", tool_calls=[tool_call])
-    node_result = node.invoke({"messages": [msg], "bar": "baz"}, store=store)
-    graph_result = graph.invoke({"messages": [msg], "bar": "baz"})
-    for result in (node_result, graph_result):
-        result["messages"][-1]
-        tool_message = result["messages"][-1]
-        assert tool_message.content == "Some val: 1, store val: bar, state val: baz", (
-            f"Failed for tool={tool_name}"
-        )
-
-    # test injected store without passing store to compiled graph
-    failing_graph = builder.compile()
-    with pytest.raises(ValueError):
-        failing_graph.invoke({"messages": [msg], "bar": "baz"})
-
-
-def test_tool_node_ensure_utf8() -> None:
-    @dec_tool
-    def get_day_list(days: list[str]) -> list[str]:
-        """choose days"""
-        return days
-
-    data = ["星期一", "水曜日", "목요일", "Friday"]
-    tools = [get_day_list]
-    tool_calls = [ToolCall(name=get_day_list.name, args={"days": data}, id="test_id")]
-    outputs: list[ToolMessage] = ToolNode(tools).invoke(
-        [AIMessage(content="", tool_calls=tool_calls)]
-    )
-    assert outputs[0].content == json.dumps(data, ensure_ascii=False)
-
-
-def test_tool_node_messages_key() -> None:
-    @dec_tool
-    def add(a: int, b: int):
-        """Adds a and b."""
-        return a + b
-
-    model = FakeToolCallingModel(
-        tool_calls=[[ToolCall(name=add.name, args={"a": 1, "b": 2}, id="test_id")]]
-    )
-
-    class State(TypedDict):
-        subgraph_messages: Annotated[list[AnyMessage], add_messages]
-
-    def call_model(state: State):
-        response = model.invoke(state["subgraph_messages"])
-        model.tool_calls = []
-        return {"subgraph_messages": response}
-
-    builder = StateGraph(State)
-    builder.add_node("agent", call_model)
-    builder.add_node("tools", ToolNode([add], messages_key="subgraph_messages"))
-    builder.add_conditional_edges(
-        "agent", partial(tools_condition, messages_key="subgraph_messages")
-    )
-    builder.add_edge(START, "agent")
-    builder.add_edge("tools", "agent")
-
-    graph = builder.compile()
-    result = graph.invoke({"subgraph_messages": [HumanMessage(content="hi")]})
-    assert result["subgraph_messages"] == [
-        _AnyIdHumanMessage(content="hi"),
-        AIMessage(
-            content="hi",
-            id="0",
-            tool_calls=[ToolCall(name=add.name, args={"a": 1, "b": 2}, id="test_id")],
-        ),
-        _AnyIdToolMessage(content="3", name=add.name, tool_call_id="test_id"),
-        AIMessage(content="hi-hi-3", id="1"),
-    ]
-
-
 @pytest.mark.parametrize("version", REACT_TOOL_CALL_VERSIONS)
-async def test_return_direct(version: str) -> None:
+@pytest.mark.parametrize(
+    "use_individual_tool_nodes",
+    [False, True],
+    ids=["single_tool_node", "node_per_tool"],
+)
+async def test_return_direct(
+    version: Literal["v1", "v2"], use_individual_tool_nodes: bool
+) -> None:
+    if version == "v1" and use_individual_tool_nodes:
+        pytest.skip("v1 does not support individual tool nodes")
+
     @dec_tool(return_direct=True)
     def tool_return_direct(input: str) -> str:
         """A tool that returns directly."""
@@ -995,6 +760,7 @@ async def test_return_direct(version: str) -> None:
         model,
         [tool_return_direct, tool_normal],
         version=version,
+        use_individual_tool_nodes=use_individual_tool_nodes,
     )
 
     # Test direct return for tool_return_direct
@@ -1088,15 +854,27 @@ def test__get_state_args() -> None:
 
 
 def test_inspect_react() -> None:
+    """Test that we can inspect the agent and its nodes."""
     model = FakeToolCallingModel(tool_calls=[])
     agent = create_react_agent(model, [])
     inspect.getclosurevars(agent.nodes["agent"].bound.func)
 
 
 @pytest.mark.parametrize("version", REACT_TOOL_CALL_VERSIONS)
+@pytest.mark.parametrize(
+    "use_individual_tool_nodes",
+    [False, True],
+    ids=["single_tool_node", "node_per_tool"],
+)
 def test_react_with_subgraph_tools(
-    sync_checkpointer: BaseCheckpointSaver, version: Literal["v1", "v2"]
+    sync_checkpointer: BaseCheckpointSaver,
+    version: Literal["v1", "v2"],
+    use_individual_tool_nodes: bool,
 ) -> None:
+    """Test React agent with subgraph tools."""
+    if version == "v1" and use_individual_tool_nodes:
+        pytest.skip("v1 does not support individual tool nodes")
+
     class State(TypedDict):
         a: int
         b: int
@@ -1152,6 +930,7 @@ def test_react_with_subgraph_tools(
         tool_node,
         checkpointer=sync_checkpointer,
         version=version,
+        use_individual_tool_nodes=use_individual_tool_nodes,
     )
     result = agent.invoke(
         {"messages": [HumanMessage(content="What's 2 + 3 and 2 * 3?")]},
@@ -1182,63 +961,18 @@ def test_react_with_subgraph_tools(
     ]
 
 
-def test_tool_node_stream_writer() -> None:
-    @dec_tool
-    def streaming_tool(x: int) -> str:
-        """Do something with writer."""
-        my_writer = get_stream_writer()
-        for value in ["foo", "bar", "baz"]:
-            my_writer({"custom_tool_value": value})
-
-        return x
-
-    tool_node = ToolNode([streaming_tool])
-    graph = (
-        StateGraph(MessagesState)
-        .add_node("tools", tool_node)
-        .add_edge(START, "tools")
-        .compile()
-    )
-
-    tool_call = {
-        "name": "streaming_tool",
-        "args": {"x": 1},
-        "id": "1",
-        "type": "tool_call",
-    }
-    inputs = {
-        "messages": [AIMessage("", tool_calls=[tool_call])],
-    }
-
-    assert list(graph.stream(inputs, stream_mode="custom")) == [
-        {"custom_tool_value": "foo"},
-        {"custom_tool_value": "bar"},
-        {"custom_tool_value": "baz"},
-    ]
-    assert list(graph.stream(inputs, stream_mode=["custom", "updates"])) == [
-        ("custom", {"custom_tool_value": "foo"}),
-        ("custom", {"custom_tool_value": "bar"}),
-        ("custom", {"custom_tool_value": "baz"}),
-        (
-            "updates",
-            {
-                "tools": {
-                    "messages": [
-                        _AnyIdToolMessage(
-                            content="1",
-                            name="streaming_tool",
-                            tool_call_id="1",
-                        ),
-                    ],
-                },
-            },
-        ),
-    ]
-
-
 @pytest.mark.parametrize("version", REACT_TOOL_CALL_VERSIONS)
-def test_react_agent_subgraph_streaming_sync(version: Literal["v1", "v2"]) -> None:
+@pytest.mark.parametrize(
+    "use_individual_tool_nodes",
+    [False, True],
+    ids=["single_tool_node", "node_per_tool"],
+)
+def test_react_agent_subgraph_streaming_sync(
+    version: Literal["v1", "v2"], use_individual_tool_nodes: bool
+) -> None:
     """Test React agent streaming when used as a subgraph node sync version"""
+    if version == "v1" and use_individual_tool_nodes:
+        pytest.skip("v1 does not support individual tool nodes")
 
     @dec_tool
     def get_weather(city: str) -> str:
@@ -1258,6 +992,7 @@ def test_react_agent_subgraph_streaming_sync(version: Literal["v1", "v2"]) -> No
         tools=[get_weather],
         prompt="You are a helpful travel assistant.",
         version=version,
+        use_individual_tool_nodes=use_individual_tool_nodes,
     )
 
     # Create a subgraph that uses the React agent as a node

libs/prebuilt/tests/test_react_agent_graph.py

@@ -15,6 +15,11 @@ def tool() -> None:
     ...
 
 
+def tool2() -> None:
+    """Another testing tool."""
+    ...
+
+
 def pre_model_hook() -> None:
     """Pre-model hook."""
     ...
@@ -49,4 +54,44 @@ def test_react_agent_graph_structure(
         post_model_hook=post_model_hook,
         response_format=response_format,
     )
+    try:
+        assert agent.get_graph().draw_mermaid(with_styles=False) == snapshot
+    except Exception as e:
+        raise ValueError(
+            "The graph structure has changed. Please update the snapshot."
+            "Configuration used:\n"
+            f"tools: {tools}, "
+            f"pre_model_hook: {pre_model_hook}, "
+            f"post_model_hook: {post_model_hook}, "
+            f"response_format: {response_format}"
+        ) from e
+
+
+@pytest.mark.parametrize("tools", [[], [tool, tool2]], ids=["no_tools", "two_tools"])
+@pytest.mark.parametrize(
+    "pre_model_hook", [None, pre_model_hook], ids=["no_pre_hook", "with_pre_hook"]
+)
+@pytest.mark.parametrize(
+    "post_model_hook", [None, post_model_hook], ids=["no_post_hook", "with_post_hook"]
+)
+@pytest.mark.parametrize(
+    "response_format",
+    [None, ResponseFormat],
+    ids=["no_response_format", "with_response_format"],
+)
+def test_react_agent_graph_structure_with_individual_nodes(
+    snapshot: SnapshotAssertion,
+    tools: list[Callable],
+    pre_model_hook: Union[Callable, None],
+    post_model_hook: Union[Callable, None],
+    response_format: Union[type[BaseModel], None],
+) -> None:
+    agent = create_react_agent(
+        model,
+        tools=tools,
+        pre_model_hook=pre_model_hook,
+        post_model_hook=post_model_hook,
+        response_format=response_format,
+        use_individual_tool_nodes=True,
+    )
     assert agent.get_graph().draw_mermaid(with_styles=False) == snapshot

libs/prebuilt/tests/test_tool_node.py

@@ -1,25 +1,49 @@
+import dataclasses
+import json
+from functools import partial
 from typing import (
     Annotated,
     Any,
+    List,
+    Type,
+    TypeVar,
     Union,
 )
 
 import pytest
 from langchain_core.messages import (
     AIMessage,
+    AnyMessage,
+    HumanMessage,
     RemoveMessage,
+    ToolCall,
     ToolMessage,
 )
 from langchain_core.tools import BaseTool, ToolException
 from langchain_core.tools import tool as dec_tool
 from pydantic import BaseModel, ValidationError
+from pydantic.v1 import BaseModel as BaseModelV1
 from pydantic.v1 import ValidationError as ValidationErrorV1
+from typing_extensions import TypedDict
 
+from langgraph.config import get_stream_writer
 from langgraph.errors import GraphBubbleUp, GraphInterrupt
-from langgraph.graph.message import REMOVE_ALL_MESSAGES
-from langgraph.prebuilt import ToolNode
-from langgraph.prebuilt.tool_node import TOOL_CALL_ERROR_TEMPLATE
+from langgraph.graph import START, MessagesState, StateGraph
+from langgraph.graph.message import REMOVE_ALL_MESSAGES, add_messages
+from langgraph.prebuilt import (
+    ToolNode,
+)
+from langgraph.prebuilt.tool_node import (
+    TOOL_CALL_ERROR_TEMPLATE,
+    InjectedState,
+    InjectedStore,
+    tools_condition,
+)
+from langgraph.store.base import BaseStore
+from langgraph.store.memory import InMemoryStore
 from langgraph.types import Command, Send
+from tests.messages import _AnyIdHumanMessage, _AnyIdToolMessage
+from tests.model import FakeToolCallingModel
 
 pytestmark = pytest.mark.anyio
 
@@ -1156,3 +1180,372 @@ async def test_tool_node_command_remove_all_messages():
     command = result[0]
     assert isinstance(command, Command)
     assert command.update == {"messages": [RemoveMessage(id=REMOVE_ALL_MESSAGES)]}
+
+
+class _InjectStateSchema(TypedDict):
+    messages: list
+    foo: str
+
+
+class _InjectedStatePydanticSchema(BaseModelV1):
+    messages: list
+    foo: str
+
+
+class _InjectedStatePydanticV2Schema(BaseModel):
+    messages: list
+    foo: str
+
+
+@dataclasses.dataclass
+class _InjectedStateDataclassSchema:
+    messages: list
+    foo: str
+
+
+T = TypeVar("T")
+
+
+@pytest.mark.parametrize(
+    "schema_",
+    [
+        _InjectStateSchema,
+        _InjectedStatePydanticSchema,
+        _InjectedStatePydanticV2Schema,
+        _InjectedStateDataclassSchema,
+    ],
+)
+def test_tool_node_inject_state(schema_: Type[T]) -> None:
+    def tool1(some_val: int, state: Annotated[T, InjectedState]) -> str:
+        """Tool 1 docstring."""
+        if isinstance(state, dict):
+            return state["foo"]
+        else:
+            return getattr(state, "foo")
+
+    def tool2(some_val: int, state: Annotated[T, InjectedState()]) -> str:
+        """Tool 2 docstring."""
+        if isinstance(state, dict):
+            return state["foo"]
+        else:
+            return getattr(state, "foo")
+
+    def tool3(
+        some_val: int,
+        foo: Annotated[str, InjectedState("foo")],
+        msgs: Annotated[List[AnyMessage], InjectedState("messages")],
+    ) -> str:
+        """Tool 1 docstring."""
+        return foo
+
+    def tool4(
+        some_val: int, msgs: Annotated[List[AnyMessage], InjectedState("messages")]
+    ) -> str:
+        """Tool 1 docstring."""
+        return msgs[0].content
+
+    node = ToolNode([tool1, tool2, tool3, tool4])
+    for tool_name in ("tool1", "tool2", "tool3"):
+        tool_call = {
+            "name": tool_name,
+            "args": {"some_val": 1},
+            "id": "some 0",
+            "type": "tool_call",
+        }
+        msg = AIMessage("hi?", tool_calls=[tool_call])
+        result = node.invoke(schema_(**{"messages": [msg], "foo": "bar"}))
+        tool_message = result["messages"][-1]
+        assert tool_message.content == "bar", f"Failed for tool={tool_name}"
+
+        if tool_name == "tool3":
+            failure_input = None
+            try:
+                failure_input = schema_(**{"messages": [msg], "notfoo": "bar"})
+            except Exception:
+                pass
+            if failure_input is not None:
+                with pytest.raises(KeyError):
+                    node.invoke(failure_input)
+
+                with pytest.raises(ValueError):
+                    node.invoke([msg])
+        else:
+            failure_input = None
+            try:
+                failure_input = schema_(**{"messages": [msg], "notfoo": "bar"})
+            except Exception:
+                # We'd get a validation error from pydantic state and wouldn't make it to the node
+                # anyway
+                pass
+            if failure_input is not None:
+                messages_ = node.invoke(failure_input)
+                tool_message = messages_["messages"][-1]
+                assert "KeyError" in tool_message.content
+                tool_message = node.invoke([msg])[-1]
+                assert "KeyError" in tool_message.content
+
+    tool_call = {
+        "name": "tool4",
+        "args": {"some_val": 1},
+        "id": "some 0",
+        "type": "tool_call",
+    }
+    msg = AIMessage("hi?", tool_calls=[tool_call])
+    result = node.invoke(schema_(**{"messages": [msg], "foo": ""}))
+    tool_message = result["messages"][-1]
+    assert tool_message.content == "hi?"
+
+    result = node.invoke([msg])
+    tool_message = result[-1]
+    assert tool_message.content == "hi?"
+
+
+def test_tool_node_inject_store() -> None:
+    store = InMemoryStore()
+    namespace = ("test",)
+
+    def tool1(some_val: int, store: Annotated[BaseStore, InjectedStore()]) -> str:
+        """Tool 1 docstring."""
+        store_val = store.get(namespace, "test_key").value["foo"]
+        return f"Some val: {some_val}, store val: {store_val}"
+
+    def tool2(some_val: int, store: Annotated[BaseStore, InjectedStore()]) -> str:
+        """Tool 2 docstring."""
+        store_val = store.get(namespace, "test_key").value["foo"]
+        return f"Some val: {some_val}, store val: {store_val}"
+
+    def tool3(
+        some_val: int,
+        bar: Annotated[str, InjectedState("bar")],
+        store: Annotated[BaseStore, InjectedStore()],
+    ) -> str:
+        """Tool 3 docstring."""
+        store_val = store.get(namespace, "test_key").value["foo"]
+        return f"Some val: {some_val}, store val: {store_val}, state val: {bar}"
+
+    node = ToolNode([tool1, tool2, tool3], handle_tool_errors=True)
+    store.put(namespace, "test_key", {"foo": "bar"})
+
+    class State(MessagesState):
+        bar: str
+
+    builder = StateGraph(State)
+    builder.add_node("tools", node)
+    builder.add_edge(START, "tools")
+    graph = builder.compile(store=store)
+
+    for tool_name in ("tool1", "tool2"):
+        tool_call = {
+            "name": tool_name,
+            "args": {"some_val": 1},
+            "id": "some 0",
+            "type": "tool_call",
+        }
+        msg = AIMessage("hi?", tool_calls=[tool_call])
+        node_result = node.invoke({"messages": [msg]}, store=store)
+        graph_result = graph.invoke({"messages": [msg]})
+        for result in (node_result, graph_result):
+            result["messages"][-1]
+            tool_message = result["messages"][-1]
+            assert tool_message.content == "Some val: 1, store val: bar", (
+                f"Failed for tool={tool_name}"
+            )
+
+    tool_call = {
+        "name": "tool3",
+        "args": {"some_val": 1},
+        "id": "some 0",
+        "type": "tool_call",
+    }
+    msg = AIMessage("hi?", tool_calls=[tool_call])
+    node_result = node.invoke({"messages": [msg], "bar": "baz"}, store=store)
+    graph_result = graph.invoke({"messages": [msg], "bar": "baz"})
+    for result in (node_result, graph_result):
+        result["messages"][-1]
+        tool_message = result["messages"][-1]
+        assert tool_message.content == "Some val: 1, store val: bar, state val: baz", (
+            f"Failed for tool={tool_name}"
+        )
+
+    # test injected store without passing store to compiled graph
+    failing_graph = builder.compile()
+    with pytest.raises(ValueError):
+        failing_graph.invoke({"messages": [msg], "bar": "baz"})
+
+
+def test_tool_node_ensure_utf8() -> None:
+    @dec_tool
+    def get_day_list(days: list[str]) -> list[str]:
+        """choose days"""
+        return days
+
+    data = ["星期一", "水曜日", "목요일", "Friday"]
+    tools = [get_day_list]
+    tool_calls = [ToolCall(name=get_day_list.name, args={"days": data}, id="test_id")]
+    outputs: list[ToolMessage] = ToolNode(tools).invoke(
+        [AIMessage(content="", tool_calls=tool_calls)]
+    )
+    assert outputs[0].content == json.dumps(data, ensure_ascii=False)
+
+
+def test_tool_node_messages_key() -> None:
+    @dec_tool
+    def add(a: int, b: int):
+        """Adds a and b."""
+        return a + b
+
+    model = FakeToolCallingModel(
+        tool_calls=[[ToolCall(name=add.name, args={"a": 1, "b": 2}, id="test_id")]]
+    )
+
+    class State(TypedDict):
+        subgraph_messages: Annotated[list[AnyMessage], add_messages]
+
+    def call_model(state: State):
+        response = model.invoke(state["subgraph_messages"])
+        model.tool_calls = []
+        return {"subgraph_messages": response}
+
+    builder = StateGraph(State)
+    builder.add_node("agent", call_model)
+    builder.add_node("tools", ToolNode([add], messages_key="subgraph_messages"))
+    builder.add_conditional_edges(
+        "agent", partial(tools_condition, messages_key="subgraph_messages")
+    )
+    builder.add_edge(START, "agent")
+    builder.add_edge("tools", "agent")
+
+    graph = builder.compile()
+    result = graph.invoke({"subgraph_messages": [HumanMessage(content="hi")]})
+    assert result["subgraph_messages"] == [
+        _AnyIdHumanMessage(content="hi"),
+        AIMessage(
+            content="hi",
+            id="0",
+            tool_calls=[ToolCall(name=add.name, args={"a": 1, "b": 2}, id="test_id")],
+        ),
+        _AnyIdToolMessage(content="3", name=add.name, tool_call_id="test_id"),
+        AIMessage(content="hi-hi-3", id="1"),
+    ]
+
+
+def test_tool_node_stream_writer() -> None:
+    @dec_tool
+    def streaming_tool(x: int) -> str:
+        """Do something with writer."""
+        my_writer = get_stream_writer()
+        for value in ["foo", "bar", "baz"]:
+            my_writer({"custom_tool_value": value})
+
+        return x
+
+    tool_node = ToolNode([streaming_tool])
+    graph = (
+        StateGraph(MessagesState)
+        .add_node("tools", tool_node)
+        .add_edge(START, "tools")
+        .compile()
+    )
+
+    tool_call = {
+        "name": "streaming_tool",
+        "args": {"x": 1},
+        "id": "1",
+        "type": "tool_call",
+    }
+    inputs = {
+        "messages": [AIMessage("", tool_calls=[tool_call])],
+    }
+
+    assert list(graph.stream(inputs, stream_mode="custom")) == [
+        {"custom_tool_value": "foo"},
+        {"custom_tool_value": "bar"},
+        {"custom_tool_value": "baz"},
+    ]
+    assert list(graph.stream(inputs, stream_mode=["custom", "updates"])) == [
+        ("custom", {"custom_tool_value": "foo"}),
+        ("custom", {"custom_tool_value": "bar"}),
+        ("custom", {"custom_tool_value": "baz"}),
+        (
+            "updates",
+            {
+                "tools": {
+                    "messages": [
+                        _AnyIdToolMessage(
+                            content="1",
+                            name="streaming_tool",
+                            tool_call_id="1",
+                        ),
+                    ],
+                },
+            },
+        ),
+    ]
+
+
+
+async def test_structured_output_tools():
+    """Test that ToolNode handles Pydantic model classes as structured output tools."""
+
+    class OutputSchema(BaseModel):
+        name: str
+        age: int
+        location: str
+
+    tool_node = ToolNode([OutputSchema])
+
+    # Test that the structured output tool is registered correctly
+    assert "OutputSchema" in tool_node.tools_by_name
+    assert "OutputSchema" in tool_node.structured_output_tools
+
+    # Create a tool call that matches the schema
+    tool_call = {
+        "name": "OutputSchema",
+        "args": {"name": "Alice", "age": 30, "location": "NYC"},
+        "id": "call_123",
+        "type": "tool_call",
+    }
+
+    # Test sync execution
+    result = tool_node.invoke(
+        {"messages": [AIMessage(content="", tool_calls=[tool_call])]}
+    )
+
+    # Should return a Command with structured response
+    assert isinstance(result, list)
+    assert len(result) == 1
+    command = result[0]
+    assert isinstance(command, Command)
+
+    # Check the update structure
+    assert "messages" in command.update
+    assert "structured_response" in command.update
+
+    # Check the tool message
+    tool_message = command.update["messages"][0]
+    assert isinstance(tool_message, ToolMessage)
+    assert tool_message.name == "OutputSchema"
+    assert tool_message.tool_call_id == "call_123"
+
+    # Check the structured response
+    structured_response = command.update["structured_response"]
+    assert isinstance(structured_response, OutputSchema)
+    assert structured_response.name == "Alice"
+    assert structured_response.age == 30
+    assert structured_response.location == "NYC"
+
+    # Test async execution
+    result_async = await tool_node.ainvoke(
+        {"messages": [AIMessage(content="", tool_calls=[tool_call])]}
+    )
+
+    # Should produce the same result
+    assert isinstance(result_async, list)
+    assert len(result_async) == 1
+    command_async = result_async[0]
+    assert isinstance(command_async, Command)
+    assert "structured_response" in command_async.update
+
+    structured_response_async = command_async.update["structured_response"]
+    assert isinstance(structured_response_async, OutputSchema)
+    assert structured_response_async.name == "Alice"