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Zhongwei Li
437
templates/ai-text-generation.ts
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437
templates/ai-text-generation.ts
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/**
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* Cloudflare Workers AI - Text Generation Examples
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*
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* This template demonstrates:
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* - Basic text generation (prompt and messages)
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* - Streaming responses (RECOMMENDED for production)
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* - Chat completions with conversation history
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* - Structured output with JSON
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* - Error handling and retry logic
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* - Rate limit management
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*/
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import { Hono } from 'hono';
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type Bindings = {
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AI: Ai;
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};
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const app = new Hono<{ Bindings: Bindings }>();
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// ============================================================================
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// Basic Text Generation
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// ============================================================================
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// Simple prompt (deprecated pattern, use messages instead)
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app.post('/simple', async (c) => {
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try {
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const { prompt } = await c.req.json<{ prompt: string }>();
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const response = await c.env.AI.run('@cf/meta/llama-3.1-8b-instruct', {
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prompt,
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});
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return c.json({
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success: true,
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response: response.response,
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});
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} catch (error) {
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return c.json(
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{
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success: false,
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error: (error as Error).message,
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},
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500
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);
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}
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});
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// ============================================================================
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// Streaming Text Generation (RECOMMENDED)
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// ============================================================================
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/**
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* Streaming is ESSENTIAL for production:
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* - Prevents buffering large responses in memory
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* - Faster time-to-first-token
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* - Better user experience
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* - Avoids Worker timeout issues
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*/
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app.post('/stream', async (c) => {
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try {
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const { prompt } = await c.req.json<{ prompt: string }>();
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const stream = await c.env.AI.run('@cf/meta/llama-3.1-8b-instruct', {
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messages: [{ role: 'user', content: prompt }],
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stream: true, // Enable streaming
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});
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return new Response(stream, {
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headers: {
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'content-type': 'text/event-stream',
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'cache-control': 'no-cache',
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connection: 'keep-alive',
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},
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});
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} catch (error) {
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return c.json(
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{
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success: false,
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error: (error as Error).message,
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},
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500
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);
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}
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});
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// ============================================================================
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// Chat Completions with History
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// ============================================================================
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app.post('/chat', async (c) => {
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try {
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const { messages } = await c.req.json<{
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messages: Array<{ role: 'system' | 'user' | 'assistant'; content: string }>;
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}>();
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// Validate messages
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if (!messages || messages.length === 0) {
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return c.json({ error: 'Messages array is required' }, 400);
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}
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const stream = await c.env.AI.run('@cf/meta/llama-3.1-8b-instruct', {
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messages,
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stream: true,
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max_tokens: 512, // Limit response length
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});
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return new Response(stream, {
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headers: { 'content-type': 'text/event-stream' },
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});
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} catch (error) {
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return c.json(
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{
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success: false,
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error: (error as Error).message,
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},
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500
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);
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}
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});
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// ============================================================================
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// Streaming with Custom Parameters
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// ============================================================================
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app.post('/stream/custom', async (c) => {
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try {
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const { prompt, temperature = 0.7, max_tokens = 512 } = await c.req.json<{
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prompt: string;
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temperature?: number;
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max_tokens?: number;
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}>();
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const stream = await c.env.AI.run('@cf/meta/llama-3.1-8b-instruct', {
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messages: [
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{
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role: 'system',
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content: 'You are a helpful AI assistant.',
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},
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{
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role: 'user',
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content: prompt,
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},
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],
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stream: true,
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max_tokens,
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temperature, // Controls randomness (0.0-1.0)
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});
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return new Response(stream, {
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headers: { 'content-type': 'text/event-stream' },
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});
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} catch (error) {
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return c.json(
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{
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success: false,
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error: (error as Error).message,
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},
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500
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);
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}
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});
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// ============================================================================
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// Structured Output (JSON)
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// ============================================================================
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/**
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* Generate structured JSON output
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* Useful for extracting data, generating schemas, etc.
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*/
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app.post('/structured', async (c) => {
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try {
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const { topic } = await c.req.json<{ topic: string }>();
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const response = await c.env.AI.run('@cf/meta/llama-3.1-8b-instruct', {
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messages: [
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{
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role: 'system',
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content:
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'You are a helpful assistant that ONLY returns valid JSON. Never include explanations or markdown, just raw JSON.',
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},
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{
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role: 'user',
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content: `Generate a recipe for ${topic}. Return JSON with keys: name, ingredients (array), instructions (array), prepTime (number in minutes)`,
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},
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],
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max_tokens: 1024,
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});
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// Parse JSON response
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const data = JSON.parse(response.response);
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return c.json({
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success: true,
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data,
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});
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} catch (error) {
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return c.json(
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{
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success: false,
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error: (error as Error).message,
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},
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500
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);
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}
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});
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// ============================================================================
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// Model Comparison
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// ============================================================================
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/**
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* Compare different models side-by-side
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*/
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app.post('/compare', async (c) => {
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try {
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const { prompt } = await c.req.json<{ prompt: string }>();
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const models = [
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'@cf/meta/llama-3.1-8b-instruct', // Balanced
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'@cf/meta/llama-3.2-1b-instruct', // Fast
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'@cf/qwen/qwen1.5-14b-chat-awq', // High quality
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];
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const results = await Promise.all(
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models.map(async (model) => {
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const start = Date.now();
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const response = await c.env.AI.run(model, {
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messages: [{ role: 'user', content: prompt }],
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max_tokens: 256,
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});
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const duration = Date.now() - start;
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return {
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model,
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response: response.response,
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duration,
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};
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})
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);
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return c.json({
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success: true,
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results,
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});
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} catch (error) {
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return c.json(
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{
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success: false,
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error: (error as Error).message,
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},
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500
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);
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}
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});
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// ============================================================================
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// Error Handling with Retry
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// ============================================================================
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/**
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* Retry logic for rate limits and transient errors
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*/
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async function runWithRetry(
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ai: Ai,
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model: string,
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inputs: any,
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maxRetries = 3
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): Promise<any> {
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let lastError: Error;
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for (let i = 0; i < maxRetries; i++) {
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try {
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return await ai.run(model, inputs);
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} catch (error) {
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lastError = error as Error;
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const message = lastError.message.toLowerCase();
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// Rate limit (429) - retry with exponential backoff
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if (message.includes('429') || message.includes('rate limit')) {
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if (i < maxRetries - 1) {
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const delay = Math.pow(2, i) * 1000; // 1s, 2s, 4s
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console.log(`Rate limited. Retrying in ${delay}ms...`);
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await new Promise((resolve) => setTimeout(resolve, delay));
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continue;
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}
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}
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// Model unavailable - try fallback model
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if (message.includes('model') && message.includes('unavailable')) {
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if (i === 0) {
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console.log('Model unavailable, trying fallback...');
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model = '@cf/meta/llama-3.2-1b-instruct'; // Faster fallback
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continue;
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}
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}
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// Other errors - throw immediately
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throw error;
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}
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}
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throw lastError!;
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}
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app.post('/reliable', async (c) => {
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try {
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const { prompt } = await c.req.json<{ prompt: string }>();
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const response = await runWithRetry(c.env.AI, '@cf/meta/llama-3.1-8b-instruct', {
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messages: [{ role: 'user', content: prompt }],
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});
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return c.json({
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success: true,
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response: response.response,
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});
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} catch (error) {
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return c.json(
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{
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success: false,
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error: (error as Error).message,
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},
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500
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);
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}
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});
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// ============================================================================
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// Token Length Validation
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// ============================================================================
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/**
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* Validate input length to prevent token limit errors
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* Approximate: 1 token ≈ 4 characters
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*/
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function estimateTokens(text: string): number {
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return Math.ceil(text.length / 4);
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}
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app.post('/validate', async (c) => {
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try {
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const { prompt } = await c.req.json<{ prompt: string }>();
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const estimatedTokens = estimateTokens(prompt);
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const maxInputTokens = 2048; // Most models support 2K-128K
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if (estimatedTokens > maxInputTokens) {
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return c.json(
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{
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success: false,
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error: `Input too long: ${estimatedTokens} tokens (max: ${maxInputTokens})`,
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},
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400
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);
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}
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const response = await c.env.AI.run('@cf/meta/llama-3.1-8b-instruct', {
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messages: [{ role: 'user', content: prompt }],
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});
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return c.json({
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success: true,
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response: response.response,
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estimatedTokens,
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});
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} catch (error) {
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return c.json(
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{
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success: false,
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error: (error as Error).message,
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},
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500
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);
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}
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});
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// ============================================================================
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// System Prompts & Personas
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// ============================================================================
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const PERSONAS = {
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helpful: 'You are a helpful AI assistant.',
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concise: 'You are a concise AI assistant. Keep responses brief.',
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technical: 'You are a technical AI assistant. Provide detailed, accurate information.',
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creative: 'You are a creative AI assistant. Be imaginative and original.',
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};
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app.post('/persona/:persona', async (c) => {
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try {
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const persona = c.req.param('persona') as keyof typeof PERSONAS;
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const { prompt } = await c.req.json<{ prompt: string }>();
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if (!PERSONAS[persona]) {
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return c.json({ error: 'Invalid persona' }, 400);
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}
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const stream = await c.env.AI.run('@cf/meta/llama-3.1-8b-instruct', {
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messages: [
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{ role: 'system', content: PERSONAS[persona] },
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{ role: 'user', content: prompt },
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],
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stream: true,
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});
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return new Response(stream, {
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headers: { 'content-type': 'text/event-stream' },
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});
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} catch (error) {
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return c.json(
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{
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success: false,
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error: (error as Error).message,
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},
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500
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);
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}
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});
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// ============================================================================
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// Health Check
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// ============================================================================
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app.get('/health', (c) => {
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return c.json({
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status: 'ok',
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timestamp: new Date().toISOString(),
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});
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});
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export default app;
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