feat: send analytics event for token usage (#37)

packages/bolt/app/routes/api.chat.ts

@@ -4,6 +4,8 @@ import { CONTINUE_PROMPT } from '~/lib/.server/llm/prompts';
 import { streamText, type Messages, type StreamingOptions } from '~/lib/.server/llm/stream-text';
 import SwitchableStream from '~/lib/.server/llm/switchable-stream';
 import { handleWithAuth } from '~/lib/.server/login';
+import { getSession } from '~/lib/.server/sessions';
+import { AnalyticsAction, AnalyticsTrackEvent, sendEventInternal } from '~/lib/analytics';
 
 export async function action(args: ActionFunctionArgs) {
   return handleWithAuth(args, chatAction);
@@ -17,8 +19,21 @@ async function chatAction({ context, request }: ActionFunctionArgs) {
   try {
     const options: StreamingOptions = {
       toolChoice: 'none',
-      onFinish: async ({ text: content, finishReason }) => {
+      onFinish: async ({ text: content, finishReason, usage }) => {
         if (finishReason !== 'length') {
+          const { session } = await getSession(request, context.cloudflare.env);
+
+          await sendEventInternal(session.data, {
+            action: AnalyticsAction.Track,
+            payload: {
+              event: AnalyticsTrackEvent.MessageComplete,
+              properties: {
+                usage,
+                finishReason,
+              },
+            },
+          });
+
           return stream.close();
         }