feat(experimental): FunctionsAgent, uses new function payload for tooling

api/app/langchain/agents/Functions/initializeFunctionsAgent.js

@@ -0,0 +1,33 @@
+const FunctionsAgent = require('./FunctionsAgent');
+const { AgentExecutor } = require('langchain/agents');
+const { BufferMemory, ChatMessageHistory } = require('langchain/memory');
+
+const initializeFunctionsAgent = async ({
+  tools,
+  model,
+  pastMessages,
+  currentDateString,
+  ...rest
+}) => {
+  const agent = FunctionsAgent.fromLLMAndTools(
+    model,
+    tools, 
+    {
+      currentDateString,
+    });
+
+  const memory = new BufferMemory({
+    chatHistory: new ChatMessageHistory(pastMessages),
+    // returnMessages: true, // commenting this out retains memory
+    memoryKey: 'chat_history',
+    humanPrefix: 'User',
+    aiPrefix: 'Assistant',
+    inputKey: 'input',
+    outputKey: 'output'
+  });
+
+  return AgentExecutor.fromAgentAndTools({ agent, tools, memory, ...rest });
+};
+
+module.exports = initializeFunctionsAgent;
+