feat: Basic trip planner agent

agent/trip-planner/nodes/classify.ts

@@ -0,0 +1,70 @@
+import { ChatOpenAI } from "@langchain/openai";
+import { TripPlannerState } from "../types";
+import { z } from "zod";
+import { formatMessages } from "agent/utils/format-messages";
+
+export async function classify(
+  state: TripPlannerState,
+): Promise<Partial<TripPlannerState>> {
+  if (!state.tripDetails) {
+    // Can not classify if tripDetails are undefined
+    return {};
+  }
+
+  const schema = z.object({
+    isRelevant: z
+      .boolean()
+      .describe(
+        "Whether the trip details are still relevant to the user's request.",
+      ),
+  });
+
+  const model = new ChatOpenAI({ model: "gpt-4o", temperature: 0 }).bindTools(
+    [
+      {
+        name: "classify",
+        description:
+          "A tool to classify whether or not the trip details are still relevant to the user's request.",
+        schema,
+      },
+    ],
+    {
+      tool_choice: "classify",
+    },
+  );
+
+  const prompt = `You're an AI assistant for planning trips. The user has already specified the following details for their trip:
+- location - ${state.tripDetails.location}
+- startDate - ${state.tripDetails.startDate}
+- endDate - ${state.tripDetails.endDate}
+- numberOfGuests - ${state.tripDetails.numberOfGuests}
+
+Your task is to carefully read over the user's conversation, and determine if their trip details are still relevant to their most recent request.
+You should set is relevant to false if they are now asking about a new location, trip duration, or number of guests.
+If they do NOT change their request details (or they never specified them), please set is relevant to true.
+`;
+
+  const humanMessage = `Here is the entire conversation so far:\n${formatMessages(state.messages)}`;
+
+  const response = await model.invoke([
+    { role: "system", content: prompt },
+    { role: "human", content: humanMessage },
+  ]);
+
+  const classificationDetails = response.tool_calls?.[0]?.args as
+    | z.infer<typeof schema>
+    | undefined;
+
+  if (!classificationDetails) {
+    throw new Error("Could not classify trip details");
+  }
+
+  if (!classificationDetails.isRelevant) {
+    return {
+      tripDetails: undefined,
+    };
+  }
+
+  // If it is relevant, return the state unchanged
+  return {};
+}