Imported from coco-research/coco (skills/ai-product/SKILL.md). Install upstream with npx skills add coco-research/coco --skill ai-product. Copyright stays with the author.

AI Product Development

Expert in shipping production-grade AI-powered features — LLM integration patterns, RAG architecture, prompt engineering that scales, AI UX that users trust, safety and guardrails, streaming, and cost optimization. Treats prompts as code, validates all outputs, and never trusts an LLM blindly.

Use when: building AI features into a product, integrating LLMs, designing RAG pipelines, implementing AI safety/guardrails, optimizing AI costs, building AI UX patterns, prompt engineering for production, handling hallucinations, streaming LLM responses, or evaluating AI output quality.

When This Skill Is Activated

1. Read this file fully before proceeding
2. Understand what AI feature the user is building
3. Apply the relevant patterns below (integration, RAG, UX, safety, cost)
4. Always address: output validation, error handling, cost awareness, user trust

Core Principle

Demos are easy. Production is hard. Every pattern below exists because something broke in production.

LLM Integration Patterns

Structured Output with Validation

Never parse free-text LLM output with regex. Use structured output modes and validate with a schema.

import { z } from "zod";
import OpenAI from "openai";

// 1. Define your schema
const ProductReviewSchema = z.object({
  sentiment: z.enum(["positive", "negative", "neutral"]),
  score: z.number().min(0).max(10),
  summary: z.string().max(200),
  keyTopics: z.array(z.string()).max(5),
});

type ProductReview = z.infer<typeof ProductReviewSchema>;

// 2. Call with structured output
const openai = new OpenAI();

async function analyzeReview(reviewText: string): Promise<ProductReview> {
  const response = await openai.chat.completions.create({
    model: "gpt-4o-mini",
    response_format: { type: "json_object" },
    messages: [
      {
        role: "system",
        content: `Analyze the product review. Return JSON matching this schema:
          { sentiment: "positive"|"negative"|"neutral", score: 0-10, summary: string, keyTopics: string[] }`,
      },
      { role: "user", content: reviewText },
    ],
  });

  const raw = JSON.parse(response.choices[0].message.content!);

  // 3. Always validate — the model can return anything
  const result = ProductReviewSchema.parse(raw);
  return result;
}

Streaming with Progress

Stream LLM responses to reduce perceived latency. Show users something is happening immediately.

async function streamResponse(prompt: string, onChunk: (text: string) => void) {
  const stream = await openai.chat.completions.create({
    model: "gpt-4o-mini",
    messages: [{ role: "user", content: prompt }],
    stream: true,
  });

  let fullText = "";
  for await (const chunk of stream) {
    const delta = chunk.choices[0]?.delta?.content || "";
    fullText += delta;
    onChunk(delta); // Update UI incrementally
  }

  return fullText;
}

// React example: streaming into state
function useStreamingAI() {
  const [text, setText] = useState("");
  const [isStreaming, setIsStreaming] = useState(false);

  const generate = async (prompt: string) => {
    setIsStreaming(true);
    setText("");
    await streamResponse(prompt, (chunk) => {
      setText((prev) => prev + chunk);
    });
    setIsStreaming(false);
  };

  return { text, isStreaming, generate };
}

Prompt Versioning and Testing

Treat prompts as code. Version them. Test with regression suites.

// prompts/v3-review-analyzer.ts
export const REVIEW_ANALYZER_PROMPT = {
  version: "3.0",
  system: `You are a product review analyst. Extract sentiment, score, summary, and topics.
    Always return valid JSON. Never hallucinate topics not mentioned in the review.`,
  temperature: 0.1, // Low temp for consistent structured output
  maxTokens: 500,
};

// tests/prompts/review-analyzer.test.ts
describe("Review Analyzer Prompt v3", () => {
  const testCases = [
    {
      input: "This product is amazing! Great battery life and beautiful screen.",
      expected: { sentiment: "positive", minScore: 7 },
    },
    {
      input: "Terrible. Broke after 2 days. Worst purchase ever.",
      expected: { sentiment: "negative", maxScore: 3 },
    },
    {
      input: "It's okay. Does what it says but nothing special.",
      expected: { sentiment: "neutral", minScore: 4, maxScore: 6 },
    },
  ];

  test.each(testCases)("correctly analyzes: $input", async ({ input, expected }) => {
    const result = await analyzeReview(input);
    expect(result.sentiment).toBe(expected.sentiment);
    if (expected.minScore) expect(result.score).toBeGreaterThanOrEqual(expected.minScore);
    if (expected.maxScore) expect(result.score).toBeLessThanOrEqual(expected.maxScore);
  });
});

RAG Architecture

When to Use RAG

RAG Pipeline

User Query
    ↓
Query Processing (rewrite, expand, decompose)
    ↓
Embedding (text → vector)
    ↓
Vector Search (find relevant chunks)
    ↓
Re-ranking (order by relevance)
    ↓
Context Assembly (fit within token budget)
    ↓
LLM Generation (with retrieved context)
    ↓
Citation Extraction + Validation
    ↓
Response with Sources

Implementation

import { OpenAI } from "openai";

const openai = new OpenAI();

// 1. Chunk documents at ingest time
function chunkDocument(text: string, maxChunkSize = 500, overlap = 50): string[] {
  const sentences = text.split(/(?<=[.!?])\s+/);
  const chunks: string[] = [];
  let current = "";

  for (const sentence of sentences) {
    if ((current + sentence).length > maxChunkSize && current) {
      chunks.push(current.trim());
      // Keep overlap for context continuity
      const words = current.split(" ");
      current = words.slice(-overlap).join(" ") + " " + sentence;
    } else {
      current += " " + sentence;
    }
  }
  if (current.trim()) chunks.push(current.trim());
  return chunks;
}

// 2. Embed and store
async function embedChunks(chunks: string[]) {
  const response = await openai.embeddings.create({
    model: "text-embedding-3-small",
    input: chunks,
  });
  return response.data.map((d, i) => ({
    text: chunks[i],
    embedding: d.embedding,
  }));
}

// 3. Retrieve relevant context
async function retrieve(query: string, topK = 5) {
  const queryEmbedding = await openai.embeddings.create({
    model: "text-embedding-3-small",
    input: query,
  });

  // Search your vector DB (Pinecone, Weaviate, pgvector, etc.)
  const results = await vectorDB.search({
    vector: queryEmbedding.data[0].embedding,
    topK,
  });

  return results.map((r) => r.metadata.text);
}

// 4. Generate with context
async function ragGenerate(query: string) {
  const context = await retrieve(query);

  const response = await openai.chat.completions.create({
    model: "gpt-4o-mini",
    messages: [
      {
        role: "system",
        content: `Answer based ONLY on the provided context. If the context doesn't contain the answer, say "I don't have enough information to answer that."
        
Context:
${context.map((c, i) => `[${i + 1}] ${c}`).join("\n\n")}`,
      },
      { role: "user", content: query },
    ],
  });

  return response.choices[0].message.content;
}

RAG Quality Checklist

• Chunk size tuned for your content type (code: larger, FAQ: smaller)
• Overlap between chunks prevents losing context at boundaries
• Query rewriting improves retrieval for vague user questions
• Re-ranking (Cohere, cross-encoder) boosts relevance over pure vector similarity
• Token budget management — don't exceed context window
• Citation tracking — map output claims back to source chunks
• Evaluation set — measure retrieval recall and answer quality regularly

AI UX Patterns — Building Trust

Show Your Work

Users trust AI more when they can see why it produced an answer.

Loading States for AI

// Bad: Spinner for 10 seconds with no context
<Spinner />

// Good: Progressive disclosure
function AILoadingState({ stage }: { stage: string }) {
  return (
    <div className="ai-loading">
      <div className="pulse-dot" />
      <span className="text-sm text-muted">{stage}</span>
    </div>
  );
}

// Usage with stages
const stages = [
  "Understanding your question...",
  "Searching relevant documents...",
  "Generating response...",
];

Error States

// Always have AI-specific error handling
function AIErrorBoundary({ error, onRetry }: { error: Error; onRetry: () => void }) {
  const messages: Record<string, string> = {
    RATE_LIMITED: "Too many requests. Please wait a moment.",
    CONTEXT_TOO_LONG: "Your input is too long. Try shortening it.",
    SAFETY_FILTERED: "This request couldn't be processed. Try rephrasing.",
    API_ERROR: "AI service is temporarily unavailable.",
  };

  return (
    <div className="ai-error">
      <p>{messages[error.message] || "Something went wrong."}</p>
      <button onClick={onRetry}>Try Again</button>
    </div>
  );
}

Safety and Guardrails

Input Sanitization

function sanitizeInput(userInput: string): string {
  // 1. Length limit
  if (userInput.length > 10_000) {
    throw new Error("CONTEXT_TOO_LONG");
  }

  // 2. Strip known injection patterns
  const cleaned = userInput
    .replace(/ignore (all |previous |above )?instructions/gi, "[filtered]")
    .replace(/you are now/gi, "[filtered]")
    .replace(/system:\s/gi, "[filtered]");

  return cleaned;
}

Output Validation

async function safeGenerate(prompt: string) {
  const response = await generate(prompt);

  // 1. Check for refusal (model declined to answer)
  if (response.includes("I cannot") || response.includes("I'm not able to")) {
    return { type: "refused", content: response };
  }

  // 2. Check for hallucinated URLs/emails
  const urls = response.match(/https?:\/\/[^\s]+/g) || [];
  const validatedUrls = await Promise.all(urls.map(validateUrl));
  if (validatedUrls.some((v) => !v)) {
    return { type: "contains_hallucinated_links", content: stripInvalidUrls(response) };
  }

  // 3. Content policy check (use a classifier or moderation endpoint)
  const moderation = await openai.moderations.create({ input: response });
  if (moderation.results[0].flagged) {
    return { type: "flagged", content: "Response filtered for safety." };
  }

  return { type: "ok", content: response };
}

Guardrail Layers

Cost Optimization

Token Budget Management

function estimateTokens(text: string): number {
  // Rough estimate: 1 token ≈ 4 characters for English
  return Math.ceil(text.length / 4);
}

function fitWithinBudget(
  systemPrompt: string,
  context: string[],
  userQuery: string,
  maxTokens: number = 120_000 // model context window
): string[] {
  const reservedForOutput = 4_000;
  const systemTokens = estimateTokens(systemPrompt);
  const queryTokens = estimateTokens(userQuery);
  let budget = maxTokens - reservedForOutput - systemTokens - queryTokens;

  const fitted: string[] = [];
  for (const chunk of context) {
    const chunkTokens = estimateTokens(chunk);
    if (chunkTokens <= budget) {
      fitted.push(chunk);
      budget -= chunkTokens;
    } else {
      break;
    }
  }
  return fitted;
}

Cost Tracking Per Feature

async function trackAICost(feature: string, userId: string, apiCall: () => Promise<any>) {
  const start = Date.now();
  const result = await apiCall();
  const duration = Date.now() - start;

  await analytics.track("ai_usage", {
    feature,         // "review-analyzer", "chat", "summarizer"
    userId,
    model: result.model,
    inputTokens: result.usage.prompt_tokens,
    outputTokens: result.usage.completion_tokens,
    cost: calculateCost(result.model, result.usage),
    latency: duration,
    cached: result.usage.prompt_tokens_details?.cached_tokens > 0,
  });

  return result;
}

Cost Reduction Playbook

Resilience Patterns

Retry with Fallback

async function resilientGenerate(prompt: string) {
  const providers = [
    { name: "openai", fn: () => callOpenAI(prompt) },
    { name: "anthropic", fn: () => callAnthropic(prompt) },
    { name: "cached", fn: () => getCachedFallback(prompt) },
  ];

  for (const provider of providers) {
    try {
      return await withRetry(provider.fn, { maxRetries: 2, backoff: "exponential" });
    } catch (error) {
      console.error(`${provider.name} failed:`, error);
      continue;
    }
  }

  throw new Error("API_ERROR");
}

async function withRetry<T>(
  fn: () => Promise<T>,
  opts: { maxRetries: number; backoff: "exponential" }
): Promise<T> {
  let lastError: Error;
  for (let i = 0; i <= opts.maxRetries; i++) {
    try {
      return await fn();
    } catch (error) {
      lastError = error as Error;
      if (i < opts.maxRetries) {
        await sleep(Math.pow(2, i) * 1000); // 1s, 2s, 4s
      }
    }
  }
  throw lastError!;
}

Async Processing for Heavy AI Tasks

// Don't block request handlers with LLM calls

// API: enqueue the job
app.post("/api/analyze", async (req, res) => {
  const jobId = await queue.add("analyze", {
    userId: req.user.id,
    input: req.body.input,
  });
  res.json({ jobId, status: "processing" });
});

// Worker: process async
queue.process("analyze", async (job) => {
  const result = await analyzeWithAI(job.data.input);
  await db.results.create({ jobId: job.id, ...result });
  await notify(job.data.userId, { jobId: job.id, status: "complete" });
});

// Client: poll or use websocket
app.get("/api/analyze/:jobId", async (req, res) => {
  const result = await db.results.findUnique({ where: { jobId: req.params.jobId } });
  res.json(result || { status: "processing" });
});

Anti-Patterns

Demo-ware

Why it fails: Demos deceive. "Works on my laptop" with hand-picked inputs. Production reveals every edge case — hallucinations, latency spikes, cost overruns, adversarial users.

Instead: Test with adversarial inputs from day one. Build evaluation sets. Monitor output quality in production. Ship with guardrails, not just a happy path.

Context Window Stuffing

Why it fails: Expensive (paying for irrelevant tokens), slow (larger prompts = higher latency), hits context limits, dilutes relevant signal with noise.

Instead: Retrieve only the most relevant context. Use re-ranking. Calculate token budget before sending. Summarize long documents before injecting.

Unstructured Output Parsing

Why it fails: Regex on free-text breaks randomly. Format changes between calls. Injection risks when users control part of the prompt.

Instead: Use JSON mode / function calling. Validate with Zod or similar schema library. Always have a fallback for malformed output.

Sharp Edges — Quick Reference

Related Skills

Works well with: ai-wrapper-product, openai-api, openai-agents, api-design-principles, frontend-design