Quickstart Guide

// app/api/chat/route.ts - withUsage wrapper (recommended)
import OpenAI from 'openai';
import { UsageTapClient } from '@usagetap/sdk';

const usageTap = new UsageTapClient({
  apiKey: process.env.USAGETAP_API_KEY!,
  baseUrl: process.env.USAGETAP_BASE_URL!,
});

const openai = new OpenAI({ apiKey: process.env.OPENAI_API_KEY! });

function selectCapabilities(allowed: {
  standard?: boolean;
  premium?: boolean;
  reasoningLevel?: 'LOW' | 'MEDIUM' | 'HIGH' | null;
  search?: boolean;
}) {
  const tier = allowed.premium ? 'premium' : 'standard';
  const model = tier === 'premium' ? 'gpt5' : 'gpt5-mini';
  const reasoningEffort =
    allowed.reasoningLevel === 'HIGH'
      ? 'high'
      : allowed.reasoningLevel === 'MEDIUM'
        ? 'medium'
        : allowed.reasoningLevel === 'LOW'
          ? 'low'
          : undefined;

  return {
    model,
    reasoning: reasoningEffort ? { effort: reasoningEffort } : undefined,
    tools: allowed.search ? [{ type: 'web_search' as const }] : undefined,
  };
}

export async function POST(req: Request) {
  const { messages } = await req.json();
  const prompt = messages
    .map((m: { role: string; content: string }) => `${m.role{'}'}: ${m.content{'}'}`)
    .join('
');

  const completion = await usageTap.withUsage(
    {
      customerId: 'quickstart-user',
      feature: 'chat.send',
      requested: { standard: true, premium: true, search: true, reasoningLevel: 'HIGH' },
    },
    async ({ begin, setUsage }) => {
      const { model, reasoning, tools } = selectCapabilities(begin.data.allowed);

      const response = await openai.responses.create({
        model,
        input: prompt,
        reasoning,
        tools,
      });

      setUsage({
        modelUsed: model,
        inputTokens: response.usage?.input_tokens ?? response.usage?.prompt_tokens ?? 0,
        responseTokens: response.usage?.output_tokens ?? response.usage?.completion_tokens ?? 0,
        reasoningTokens: reasoning ? response.usage?.reasoning_tokens ?? 0 : 0,
        searches: tools?.length ? response.usage?.web_search_queries ?? 0 : 0,
      });

      return response;
    },
  );

  return new Response(completion.output_text ?? '', {
    headers: { 'Content-Type': 'text/plain' },
  });
}

// app/api/chat/route.ts - Minimal wrapOpenAI
import OpenAI from 'openai';
import { UsageTapClient } from '@usagetap/sdk';
import { wrapOpenAI } from '@usagetap/sdk/openai';

const usageTap = new UsageTapClient({
  apiKey: process.env.USAGETAP_API_KEY!,
  baseUrl: process.env.USAGETAP_BASE_URL!,
});

const openai = new OpenAI({ apiKey: process.env.OPENAI_API_KEY! });

const ai = wrapOpenAI(openai, usageTap, {
  defaultContext: {
    customerId: 'quickstart-user',
    feature: 'chat.send',
    requested: { standard: true, premium: true, search: true, reasoningLevel: 'HIGH' },
  },
});

export async function POST(req: Request) {
  const { messages } = await req.json();

  // wrapOpenAI automatically selects gpt5 (premium) or gpt5-mini (standard)
  // based on begin.data.allowed
  const completion = await ai.chat.completions.create(
    { messages },
    {
      usageTap: {
        requested: { standard: true, premium: true, search: true, reasoningLevel: 'MEDIUM' },
      },
    },
  );

  return new Response(completion.choices[0]?.message?.content ?? '', {
    headers: { 'Content-Type': 'text/plain' },
  });
}