feat: support tool call

app/api/langchain/tool/agent/agentapi.ts

@@ -7,7 +7,10 @@ import { BaseCallbackHandler } from "langchain/callbacks";
 
 import { AIMessage, HumanMessage, SystemMessage } from "langchain/schema";
 import { BufferMemory, ChatMessageHistory } from "langchain/memory";
-import { initializeAgentExecutorWithOptions } from "langchain/agents";
+import {
+  AgentExecutor,
+  initializeAgentExecutorWithOptions,
+} from "langchain/agents";
 import { ACCESS_CODE_PREFIX, ServiceProvider } from "@/app/constant";
 
 import * as langchainTools from "langchain/tools";
@@ -17,6 +20,14 @@ import { DynamicTool, Tool } from "langchain/tools";
 import { BaiduSearch } from "@/app/api/langchain-tools/baidu_search";
 import { GoogleSearch } from "@/app/api/langchain-tools/google_search";
 import { useAccessStore } from "@/app/store";
+import { DynamicStructuredTool, formatToOpenAITool } from "langchain/tools";
+import { formatToOpenAIToolMessages } from "langchain/agents/format_scratchpad/openai_tools";
+import {
+  OpenAIToolsAgentOutputParser,
+  type ToolsAgentStep,
+} from "langchain/agents/openai/output_parser";
+import { RunnableSequence } from "langchain/schema/runnable";
+import { ChatPromptTemplate, MessagesPlaceholder } from "langchain/prompts";
 
 export interface RequestMessage {
   role: string;
@@ -92,9 +103,9 @@ export class AgentApi {
         await writer.close();
       },
       async handleChainEnd(outputs, runId, parentRunId, tags) {
-        console.log("[handleChainEnd]");
-        await writer.ready;
-        await writer.close();
+        // console.log("[handleChainEnd]");
+        // await writer.ready;
+        // await writer.close();
       },
       async handleLLMEnd() {
         // await writer.ready;
@@ -111,10 +122,10 @@ export class AgentApi {
         );
         await writer.close();
       },
-      handleLLMStart(llm, _prompts: string[]) {
+      async handleLLMStart(llm, _prompts: string[]) {
         // console.log("handleLLMStart: I'm the second handler!!", { llm });
       },
-      handleChainStart(chain) {
+      async handleChainStart(chain) {
         // console.log("handleChainStart: I'm the second handler!!", { chain });
       },
       async handleAgentAction(action) {
@@ -141,14 +152,16 @@ export class AgentApi {
           await writer.close();
         }
       },
-      handleToolStart(tool, input) {
+      async handleToolStart(tool, input) {
         // console.log("[handleToolStart]", { tool });
       },
       async handleToolEnd(output, runId, parentRunId, tags) {
         // console.log("[handleToolEnd]", { output, runId, parentRunId, tags });
       },
-      handleAgentEnd(action, runId, parentRunId, tags) {
-        // console.log("[handleAgentEnd]");
+      async handleAgentEnd(action, runId, parentRunId, tags) {
+        console.log("[handleAgentEnd]");
+        await writer.ready;
+        await writer.close();
       },
     });
   }
@@ -288,13 +301,13 @@ export class AgentApi {
             pastMessages.push(new AIMessage(message.content));
         });
 
-      const memory = new BufferMemory({
-        memoryKey: "chat_history",
-        returnMessages: true,
-        inputKey: "input",
-        outputKey: "output",
-        chatHistory: new ChatMessageHistory(pastMessages),
-      });
+      // const memory = new BufferMemory({
+      //   memoryKey: "chat_history",
+      //   returnMessages: true,
+      //   inputKey: "input",
+      //   outputKey: "output",
+      //   chatHistory: new ChatMessageHistory(pastMessages),
+      // });
 
       let llm = new ChatOpenAI(
         {
@@ -324,13 +337,48 @@ export class AgentApi {
           azureOpenAIBasePath: baseUrl,
         });
       }
-
-      const executor = await initializeAgentExecutorWithOptions(tools, llm, {
-        agentType: "openai-functions",
-        returnIntermediateSteps: reqBody.returnIntermediateSteps,
-        maxIterations: reqBody.maxIterations,
-        memory: memory,
+      const memory = new BufferMemory({
+        memoryKey: "history",
+        inputKey: "question",
+        outputKey: "answer",
+        returnMessages: true,
+        chatHistory: new ChatMessageHistory(pastMessages),
       });
+      const prompt = ChatPromptTemplate.fromMessages([
+        new MessagesPlaceholder("chat_history"),
+        ["human", "{input}"],
+        new MessagesPlaceholder("agent_scratchpad"),
+      ]);
+      const modelWithTools = llm.bind({ tools: tools.map(formatToOpenAITool) });
+      const runnableAgent = RunnableSequence.from([
+        {
+          input: (i: { input: string; steps: ToolsAgentStep[] }) => i.input,
+          agent_scratchpad: (i: { input: string; steps: ToolsAgentStep[] }) =>
+            formatToOpenAIToolMessages(i.steps),
+          chat_history: async (_: {
+            input: string;
+            steps: ToolsAgentStep[];
+          }) => {
+            const { history } = await memory.loadMemoryVariables({});
+            return history;
+          },
+        },
+        prompt,
+        modelWithTools,
+        new OpenAIToolsAgentOutputParser(),
+      ]).withConfig({ runName: "OpenAIToolsAgent" });
+
+      const executor = AgentExecutor.fromAgentAndTools({
+        agent: runnableAgent,
+        tools,
+      });
+
+      // const executor = await initializeAgentExecutorWithOptions(tools, llm, {
+      //   agentType: "openai-functions",
+      //   returnIntermediateSteps: reqBody.returnIntermediateSteps,
+      //   maxIterations: reqBody.maxIterations,
+      //   memory: memory,
+      // });
 
       executor.call(
         {