feat: Basic trip planner agent

agent/trip-planner/types.ts

@@ -0,0 +1,18 @@
+import { Annotation } from "@langchain/langgraph";
+import { GenerativeUIAnnotation } from "../types";
+
+export type TripDetails = {
+  location: string;
+  startDate: Date;
+  endDate: Date;
+  numberOfGuests: number;
+};
+
+export const TripPlannerAnnotation = Annotation.Root({
+  messages: GenerativeUIAnnotation.spec.messages,
+  ui: GenerativeUIAnnotation.spec.ui,
+  timestamp: GenerativeUIAnnotation.spec.timestamp,
+  tripDetails: Annotation<TripDetails | undefined>(),
+});
+
+export type TripPlannerState = typeof TripPlannerAnnotation.State;