Week One: Working Prototype

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import OpenAI from 'openai';

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

async function generateResponse(userInput: string): Promise<string> {
  const startTime = Date.now();
  
  try {
    const completion = await openai.chat.completions.create({
      model: 'gpt-4-turbo-preview',

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import OpenAI from 'openai';
import { APIError, RateLimitError, AuthenticationError } from 'openai';

class AIService {
  private openai: OpenAI;
  private maxRetries = 3;

  constructor() {
    this.openai = new OpenAI({ apiKey: process.env.OPENAI_API_KEY });
  }

  async generate(prompt: string): Promise<{ success: boolean; data?: string; error?: string }> {

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// Next.js + Vercel AI SDK - Complete Day 2 setup
import { useChat } from 'ai/react';
import { useState } from 'react';

export default function Prototype() {
  const [showDebug, setShowDebug] = useState(true);
  const { messages, input, handleInputChange, handleSubmit, isLoading, error } = useChat({
    api: '/api/chat',
    onResponse: (response) => {
      console.log('Response started:', response.status);
    },
    onFinish: (message) => {

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// Robust API call with specific error handling
async function callAIWithErrorHandling(input: string, context: string) {
  const startTime = Date.now();
  
  try {
    // Check input validity before API call
    if (!input.trim()) {
      return { error: 'empty_input', message: 'Please enter something to analyze.' };
    }
    
    const tokenCount = estimateTokens(input + context);
    if (tokenCount > 14000) {

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import OpenAI from 'openai';
import { RateLimiter } from 'limiter';

const client = new OpenAI({ apiKey: process.env.OPENAI_API_KEY });
const limiter = new RateLimiter({ tokensPerInterval: 50, interval: 'minute' });

interface AIResponse {
  content: string;
  usage: { prompt_tokens: number; completion_tokens: number };
  latency_ms: number;
}

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type ErrorType = 'rate_limit' | 'timeout' | 'auth' | 'content_filter' | 'network' | 'unknown';

interface HandledError {
  type: ErrorType;
  userMessage: string;
  retryable: boolean;
  retryAfterMs?: number;
}

const ERROR_MESSAGES: Record<ErrorType, string> = {
  rate_limit: "We're experiencing high demand. Your request is queued and will process shortly.",
  timeout: "This request is taking longer than usual. Would you like to try again with a shorter prompt?",

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// Minimal analytics for prototype testing - no external dependencies
const ANALYTICS_ENDPOINT = '/api/analytics';

interface AnalyticsEvent {
  event: string;
  properties?: Record<string, any>;
  timestamp: number;
  sessionId: string;
}

const sessionId = crypto.randomUUID();
const eventQueue: AnalyticsEvent[] = [];