TypeScript Interface & Type Guard Generator

import { GoogleGenAI } from '@google/genai';

const ai = new GoogleGenAI({ apiKey: process.env.GEMINI_API_KEY });

async function runPrompt(variables: Record<string, string>) {
  let promptText = `Convert this JSON payload into production-ready TypeScript interfaces.

JSON Input:
{{json_payload}}

Requirements:
- Proper naming conventions
- Optional fields marked with ?
- Nested objects separated into sub-interfaces
- Include a type guard function for runtime validation`;
  Object.entries(variables).forEach(([key, val]) => {
    promptText = promptText.replace(new RegExp(`{{\\s*${key}\\s*}}`, 'g'), val);
  });

  const response = await ai.models.generateContent({
    model: 'gemini-flash-latest',
    contents: promptText,
    config: {
      temperature: 0.7,
      systemInstruction: `You are a Senior Frontend Engineer who prioritizes strict type safety and modern TypeScript best practices.`,
    },
  });

  return response.text;
}