feat: Basic trip planner agent

agent/trip-planner/index.tsx

@@ -0,0 +1,51 @@
+import { StateGraph, START, END } from "@langchain/langgraph";
+import { TripPlannerAnnotation, TripPlannerState } from "./types";
+import { extraction } from "./nodes/extraction";
+import { callTools } from "./nodes/tools";
+import { classify } from "./nodes/classify";
+
+function routeStart(state: TripPlannerState): "classify" | "extraction" {
+  if (!state.tripDetails) {
+    return "extraction";
+  }
+
+  return "classify";
+}
+
+function routeAfterClassifying(
+  state: TripPlannerState,
+): "callTools" | "extraction" {
+  // if `tripDetails` is undefined, this means they are not relevant to the conversation
+  if (!state.tripDetails) {
+    return "extraction";
+  }
+
+  // otherwise, they are relevant, and we should route to callTools
+  return "callTools";
+}
+
+function routeAfterExtraction(
+  state: TripPlannerState,
+): "callTools" | typeof END {
+  // if `tripDetails` is undefined, this means they're missing some fields.
+  if (!state.tripDetails) {
+    return END;
+  }
+
+  return "callTools";
+}
+
+const builder = new StateGraph(TripPlannerAnnotation)
+  .addNode("classify", classify)
+  .addNode("extraction", extraction)
+  .addNode("callTools", callTools)
+  .addConditionalEdges(START, routeStart, ["classify", "extraction"])
+  .addConditionalEdges("classify", routeAfterClassifying, [
+    "callTools",
+    "extraction",
+  ])
+  .addConditionalEdges("extraction", routeAfterExtraction, ["callTools", END])
+  .addEdge("callTools", END);
+
+export const tripPlannerGraph = builder.compile();
+tripPlannerGraph.name = "Trip Planner";