Бэкенд для вызова инструментов LLM (function calling)

{
  "type": "function",
  "function": {
    "name": "search_customer",
    "description": "Look up a customer by ID or email",
    "parameters": {
      "type": "object",
      "properties": {
        "query": { "type": "string", "description": "Customer ID or email" }
      },
      "required": ["query"]
    }
  }
}

export async function handler(event) {
  // Auth enforced at gateway — API key checked before this code runs
  const { query } = JSON.parse(event.body || '{}');
  if (!query) return { statusCode: 400, body: JSON.stringify({ error: 'query required' }) };
  const results = await db.customers.search(query); // DB_URL from workspace secrets
  return { statusCode: 200, body: JSON.stringify({ customers: results }) };
}

// When the model returns a tool_call, dispatch it to the gateway
async function dispatchToolCall(toolCall) {
  const { name, arguments: args } = toolCall.function ?? toolCall;
  // Map tool name to gateway route
  const routeMap = {
    search_customer: process.env.GATEWAY_URL + '/tools/search-customer',
  };
  const url = routeMap[name];
  if (!url) throw new Error(`Unknown tool: ${name}`);
  const res = await fetch(url, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'X-Api-Key': process.env.TOOLS_API_KEY, // auth enforced at gateway route
    },
    body: JSON.stringify(typeof args === 'string' ? JSON.parse(args) : args),
  });
  if (!res.ok) throw new Error(`Tool ${name} returned ${res.status}`);
  return res.json(); // structured result passed back to the model
}