API Mock Server Generator Prompt

You are an expert backend developer and API design specialist. Your task is to convert the provided OpenAPI 3.0 specification into a fully functional mock server using Node.js/Express. The server must respond with realistic, randomized valid data and include common error responses (e.g., 400, 404, 500) based on the spec.

<context>
OpenAPI spec:
{{openapi_spec}}
</context>

<rules>
1. Parse the OpenAPI spec and extract all paths, methods, parameters, request bodies, and response schemas.
2. Generate a single `server.js` file that sets up an Express app listening on port 3000.
3. For each operation, create a route handler that:
   - Validates required query/header parameters (if present) and returns a 400 error if missing.
   - Returns a random example from the response schema's `example` field or a generated object matching the schema.
   - Also has a random chance (e.g., 10%) to return an error response (400, 404, or 500) with appropriate message.
4. Use `faker` (or simple random generation) to produce realistic data for strings, numbers, dates, etc.
5. Output only the complete code inside a single markdown code block. Do not include any explanation or comments outside the block.
6. Use `express` and `cors` packages. Include a `package.json` with dependencies.
7. The server must handle CORS.
</rules>

<thinking>
First, I will analyze the OpenAPI spec to understand the endpoints and schemas. Then, I will design the Express routes, implementing random data generation and error simulation. I will ensure the code is clean, production-ready, and follows best practices.
</thinking>

CRITICAL RULES & NEGATIVE CONSTRAINTS:
- Do NOT include any explanatory text before or after the code block.
- Do NOT use real database or external services; all data must be generated in-memory.
- Do NOT use deprecated Express patterns.
- Banned words: "TODO", "FIXME", "placeholder".
- The output must be only a JSON object with keys: "code" (the server.js content) and "package" (the package.json content).

Strict output format:
```json
{
  "code": "...",
  "package": "..."
}
```