Merge pull request #1 from langchain-ai/jacob/updates

Update comments and documentation

.env.example

@@ -1,4 +1,3 @@
 # Copy this over:
 # cp .env.example .env
-# Then modify to suit your needs
-ANTHROPIC_API_KEY=...
+# Then modify to suit your needs

README.md

@@ -16,23 +16,20 @@ The simple chatbot:
 
 1. Takes a user **message** as input
 2. Maintains a history of the conversation
-3. Generates a response based on the current message and conversation history
-4. Updates the conversation history with the new interaction
+3. Returns a placeholder response, updating the conversation history
 
 This template provides a foundation that can be easily customized and extended to create more complex conversational agents.
 
 ## Getting Started
 
 Assuming you have already [installed LangGraph Studio](https://github.com/langchain-ai/langgraph-studio?tab=readme-ov-file#download), to set up:
 
-1. Create a `.env` file.
+1. Create a `.env` file. This template does not require any environment variables by default, but you will likely want to add some when customizing.
 
 ```bash
 cp .env.example .env
 ```
 
-2. Define required API keys in your `.env` file.
-
 <!--
 Setup instruction auto-generated by `langgraph template lock`. DO NOT EDIT MANUALLY.
 -->
@@ -41,20 +38,19 @@ Setup instruction auto-generated by `langgraph template lock`. DO NOT EDIT MANUA
 End setup instructions
 -->
 
+2. Open the folder in LangGraph Studio!
 3. Customize the code as needed.
-4. Open the folder in LangGraph Studio!
 
 ## How to customize
 
-1. **Modify the system prompt**: The default system prompt is defined in [configuration.ts](./src/agent/configuration.ts). You can easily update this via configuration in the studio to change the chatbot's personality or behavior.
-2. **Select a different model**: We default to Anthropic's Claude 3 Sonnet. You can select a compatible chat model using `provider/model-name` via configuration. Example: `openai/gpt-4-turbo-preview`.
-3. **Extend the graph**: The core logic of the chatbot is defined in [graph.ts](./src/agent/graph.ts). You can modify this file to add new nodes, edges, or change the flow of the conversation.
+1. **Add an LLM call**: You can select and install a chat model wrapper from [the LangChain.js ecosystem](https://js.langchain.com/docs/integrations/chat/), or use LangGraph.js without LangChain.js.
+2. **Extend the graph**: The core logic of the chatbot is defined in [graph.ts](./src/agent/graph.ts). You can modify this file to add new nodes, edges, or change the flow of the conversation.
 
-You can also quickly extend this template by:
+You can also extend this template by:
 
-- Adding custom tools or functions to enhance the chatbot's capabilities.
+- Adding [custom tools or functions](https://js.langchain.com/docs/how_to/tool_calling) to enhance the chatbot's capabilities.
 - Implementing additional logic for handling specific types of user queries or tasks.
-- Integrating external APIs or databases to provide more dynamic responses.
+- Add retrieval-augmented generation (RAG) capabilities by integrating [external APIs or databases](https://langchain-ai.github.io/langgraphjs/tutorials/rag/langgraph_agentic_rag/) to provide more customized responses.
 
 ## Development
 
@@ -81,4 +77,3 @@ Configuration auto-generated by `langgraph template lock`. DO NOT EDIT MANUALLY.
   }
 }
 -->
-

langgraph.json

@@ -1,7 +1,7 @@
 {
   "node_version": "20",
   "graphs": {
-    "agent": "./src/agent.ts:graph"
+    "agent": "./src/agent/graph.ts:graph"
   },
   "env": ".env"
 }

package.json

@@ -21,13 +21,12 @@
     "test:all": "yarn test && yarn test:int && yarn lint:langgraph"
   },
   "dependencies": {
-    "@langchain/core": "^0.3.1",
-    "@langchain/langgraph": "^0.2.3"
+    "@langchain/core": "^0.3.2",
+    "@langchain/langgraph": "^0.2.5"
   },
   "devDependencies": {
     "@eslint/eslintrc": "^3.1.0",
     "@eslint/js": "^9.9.1",
-    "@langchain/openai": "^0.2.7",
     "@tsconfig/recommended": "^1.0.7",
     "@types/jest": "^29.5.0",
     "@typescript-eslint/eslint-plugin": "^5.59.8",

src/agent/graph.ts

@@ -1,35 +1,82 @@
 /**
- * Empty LangGraph Template
- *
+ * Starter LangGraph.js Template
  * Make this code your own!
  */
-
 import { StateGraph } from "@langchain/langgraph";
-import { StateAnnotation, State } from "./state.js";
-import { AIMessage } from "@langchain/core/messages";
-import { ensureConfiguration } from "./configuration.js";
 import { RunnableConfig } from "@langchain/core/runnables";
+import { StateAnnotation } from "./state.js";
 
-// Define nodes, these do the work:
-
-const callModel = async (_state: State, config: RunnableConfig) => {
-  // Do some work... (e.g. call an LLM)
-  const configuration = ensureConfiguration(config);
+/**
+ * Define a node, these do the work of the graph and should have most of the logic.
+ * Must return a subset of the properties set in StateAnnotation.
+ * @param state The current state of the graph.
+ * @param config Extra parameters passed into the state graph.
+ * @returns Some subset of parameters of the graph state, used to update the state
+ * for the edges and nodes executed next.
+ */
+const callModel = async (
+  state: typeof StateAnnotation.State,
+  _config: RunnableConfig,
+): Promise<typeof StateAnnotation.Update> => {
+  /**
+   * Do some work... (e.g. call an LLM)
+   * For example, with LangChain you could do something like:
+   *
+   * ```bash
+   * $ npm i @langchain/anthropic
+   * ```
+   *
+   * ```ts
+   * import { ChatAnthropic } from "@langchain/anthropic";
+   * const model = new ChatAnthropic({
+   *   model: "claude-3-5-sonnet-20240620",
+   *   apiKey: process.env.ANTHROPIC_API_KEY,
+   * });
+   * const res = await model.invoke(state.messages);
+   * ```
+   *
+   * Or, with an SDK directly:
+   *
+   * ```bash
+   * $ npm i openai
+   * ```
+   *
+   * ```ts
+   * import OpenAI from "openai";
+   * const openai = new OpenAI({
+   *   apiKey: process.env.OPENAI_API_KEY,
+   * });
+   *
+   * const chatCompletion = await openai.chat.completions.create({
+   *   messages: [{
+   *     role: state.messages[0]._getType(),
+   *     content: state.messages[0].content,
+   *   }],
+   *   model: "gpt-4o-mini",
+   * });
+   * ```
+   */
+  console.log("Current state:", state);
   return {
-    messages: [new AIMessage(`Hi, there! This is ${configuration.modelName}`)],
+    messages: [
+      {
+        role: "assistant",
+        content: `Hi there! How are you?`,
+      },
+    ],
   };
 };
 
-// Define conditional edge logic:
-
 /**
  * Routing function: Determines whether to continue research or end the builder.
  * This function decides if the gathered information is satisfactory or if more research is needed.
  *
  * @param state - The current state of the research builder
  * @returns Either "callModel" to continue research or END to finish the builder
  */
-export const _route = (state: State): "__end__" | "callModel" => {
+export const route = (
+  state: typeof StateAnnotation.State,
+): "__end__" | "callModel" => {
   if (state.messages.length > 0) {
     return "__end__";
   }
@@ -50,8 +97,8 @@ const builder = new StateGraph(StateAnnotation)
   // and represent the beginning and end of the builder.
   .addEdge("__start__", "callModel")
   // Conditional edges optionally route to different nodes (or end)
-  //
-  .addConditionalEdges("callModel", _route);
+  .addConditionalEdges("callModel", route);
 
 export const graph = builder.compile();
+
 graph.name = "New Agent";

src/agent/state.ts

@@ -1,50 +1,59 @@
-import { BaseMessage } from "@langchain/core/messages";
+import { BaseMessage, BaseMessageLike } from "@langchain/core/messages";
 import { Annotation, messagesStateReducer } from "@langchain/langgraph";
 
 /**
- * A graph's StateAnnotation defines three main thing:
+ * A graph's StateAnnotation defines three main things:
  * 1. The structure of the data to be passed between nodes (which "channels" to read from/write to and their types)
- * 2. Default values each field
- * 3. Rducers for the state's. Reducers are functions that determine how to apply updates to the state.
+ * 2. Default values for each field
+ * 3. Reducers for the state's. Reducers are functions that determine how to apply updates to the state.
  * See [Reducers](https://langchain-ai.github.io/langgraphjs/concepts/low_level/#reducers) for more information.
  */
 
 // This is the primary state of your agent, where you can store any information
 export const StateAnnotation = Annotation.Root({
   /**
    * Messages track the primary execution state of the agent.
-
-    Typically accumulates a pattern of:
-
-    1. HumanMessage - user input
-    2. AIMessage with .tool_calls - agent picking tool(s) to use to collect
-         information
-    3. ToolMessage(s) - the responses (or errors) from the executed tools
-    
-        (... repeat steps 2 and 3 as needed ...)
-    4. AIMessage without .tool_calls - agent responding in unstructured
-        format to the user.
-
-    5. HumanMessage - user responds with the next conversational turn.
-
-        (... repeat steps 2-5 as needed ... )
-    
-    Merges two lists of messages, updating existing messages by ID.
-
-    By default, this ensures the state is "append-only", unless the
-    new message has the same ID as an existing message.
-
-    Returns:
-        A new list of messages with the messages from \`right\` merged into \`left\`.
-        If a message in \`right\` has the same ID as a message in \`left\`, the
-        message from \`right\` will replace the message from \`left\`.`
+   *
+   * Typically accumulates a pattern of:
+   *
+   * 1. HumanMessage - user input
+   * 2. AIMessage with .tool_calls - agent picking tool(s) to use to collect
+   *     information
+   * 3. ToolMessage(s) - the responses (or errors) from the executed tools
+   *
+   *     (... repeat steps 2 and 3 as needed ...)
+   * 4. AIMessage without .tool_calls - agent responding in unstructured
+   *     format to the user.
+   *
+   * 5. HumanMessage - user responds with the next conversational turn.
+   *
+   *     (... repeat steps 2-5 as needed ... )
+   *
+   * Merges two lists of messages or message-like objects with role and content,
+   * updating existing messages by ID.
+   *
+   * Message-like objects are automatically coerced by `messagesStateReducer` into
+   * LangChain message classes. If a message does not have a given id,
+   * LangGraph will automatically assign one.
+   *
+   * By default, this ensures the state is "append-only", unless the
+   * new message has the same ID as an existing message.
+   *
+   * Returns:
+   *     A new list of messages with the messages from \`right\` merged into \`left\`.
+   *     If a message in \`right\` has the same ID as a message in \`left\`, the
+   *     message from \`right\` will replace the message from \`left\`.`
    */
-  messages: Annotation<BaseMessage[]>({
+  messages: Annotation<BaseMessage[], BaseMessageLike[]>({
     reducer: messagesStateReducer,
     default: () => [],
   }),
-  // Feel free to add additional attributes to your state as needed.
-  // Common examples include retrieved documents, extracted entities, API connections, etc.
+  /**
+   * Feel free to add additional attributes to your state as needed.
+   * Common examples include retrieved documents, extracted entities, API connections, etc.
+   *
+   * For simple fields whose value should be overwritten by the return value of a node,
+   * you don't need to define a reducer or default.
+   */
+  // additionalField: Annotation<string>,
 });
-
-export type State = typeof StateAnnotation.State;

tests/agent.test.ts

@@ -1,8 +1,8 @@
 import { describe, it, expect } from "@jest/globals";
-import { _route } from "../src/agent/graph.js";
+import { route } from "../src/agent/graph.js";
 describe("Routers", () => {
   it("Test route", async () => {
-    const res = _route({ messages: [] });
+    const res = route({ messages: [] });
     expect(res).toEqual("callModel");
   }, 100_000);
 });