Memory support for OpenAI Functions Agent (#1638)

* Memory support for OpenAI Functions Agent

* Add test, fix .run() method

* Update executor.ts

* Update langchain/src/agents/tests/openai.int.test.ts

* Fix type

---------

Co-authored-by: Nuno Campos <nuno@boringbits.io>

langchain/src/agents/initialize.ts

@@ -86,7 +86,6 @@ export type InitializeAgentExecutorOptionsStructured =
   | ({
       agentType: "openai-functions";
       agentArgs?: Parameters<typeof OpenAIAgent.fromLLMAndTools>[2];
-      memory?: never;
     } & Omit<AgentExecutorInput, "agent" | "tools">);
 
 /**
@@ -169,10 +168,17 @@ export async function initializeAgentExecutorWithOptions(
       return executor;
     }
     case "openai-functions": {
-      const { agentArgs, ...rest } = options;
+      const { agentArgs, memory, ...rest } = options;
       const executor = AgentExecutor.fromAgentAndTools({
         agent: OpenAIAgent.fromLLMAndTools(llm, tools, agentArgs),
         tools,
+        memory:
+          memory ??
+          new BufferMemory({
+            returnMessages: true,
+            memoryKey: "chat_history",
+            inputKey: "input",
+          }),
         ...rest,
       });
       return executor;

langchain/src/agents/openai/index.ts

@@ -82,6 +82,7 @@ export class OpenAIAgent extends Agent {
     const { prefix = PREFIX } = fields || {};
     return ChatPromptTemplate.fromPromptMessages([
       SystemMessagePromptTemplate.fromTemplate(prefix),
+      new MessagesPlaceholder("chat_history"),
       HumanMessagePromptTemplate.fromTemplate("{input}"),
       new MessagesPlaceholder("agent_scratchpad"),
     ]);

langchain/src/agents/tests/openai.int.test.ts

@@ -25,6 +25,12 @@ test("OpenAIAgent", async () => {
   const result = await executor.run("What is the weather in New York?");
 
   console.log(result);
+
+  const result2 = await executor.run(
+    "And what is the weather like in the capital of that state?"
+  );
+
+  console.log(result2);
 });
 
 test("OpenAIAgent streaming", async () => {