> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ai-stats.phaseo.app/llms.txt
> Use this file to discover all available pages before exploring further.

# Structured Output Validation

> Server-side validation, retries, and fallback strategies for structured output.

Even with schema-constrained generation, always validate output on your server.

## Recommended loop

1. Request schema-constrained output.
2. Parse JSON.
3. Validate against your server schema.
4. Retry once with a corrective prompt if invalid.
5. Fallback to safe failure if still invalid.

## Validation example (TypeScript)

```typescript theme={null}
import { z } from "zod";

const Summary = z.object({
  order_id: z.string(),
  total_usd: z.number(),
  status: z.enum(["pending", "paid", "failed"]),
});

function parseStructuredContent(content: string) {
  const data = JSON.parse(content);
  return Summary.parse(data);
}
```

## Corrective retry prompt

When validation fails, send a short corrective instruction:

`Your previous output did not match schema. Return valid JSON only, with required fields and no extra keys.`

## Production guidance

* Keep one schema per use case and version it.
* Track validation failure rates by model id.
* Alert on sudden schema failure spikes after model changes.