agentic-json-repair

Repair and validate AI-generated JSON with auto-generated retry prompts. Perfect for building reliable AI agents and LLM pipelines.

Features

• 🔧 Auto-repair malformed JSON (missing quotes, trailing commas, etc.)
• 📝 Extract JSON from markdown code blocks or mixed prose
• ✅ Validate against Zod schemas with full type inference
• 🔄 Auto-generate retry prompts when validation fails

Installation

npm install agentic-json-repair zod

Usage

import { safeParseAI } from 'agentic-json-repair';
import { z } from 'zod';

// Define your expected schema
const UserSchema = z.object({
  name: z.string(),
  age: z.number(),
});

// Parse messy AI output
const aiOutput = `
  Sure! Here is the user data:
  \`\`\`json
  {
    name: "Alice",
    age: 30,
  }
  \`\`\`
`;

const result = safeParseAI(aiOutput, UserSchema);

if (result.success) {
  console.log(result.data); // { name: "Alice", age: 30 } - fully typed!
} else {
  // Use retry prompt to ask the AI to fix the output
  console.log(result.retryPrompt);
}

API

safeParseAI<T>(aiOutput: string, schema: ZodType<T>): AgenticParseResult<T>

Attempts to extract, repair, and validate JSON from an AI's text output.

Returns:

// On success
{ success: true; data: T }

// On failure
{ success: false; error: string; retryPrompt: string }

What it handles

| Problem | Example | Fixed | |---------|---------|-------| | Markdown code blocks | ```json {...} ``` | ✅ | | Surrounding prose | "Here's the JSON: {...}" | ✅ | | Unquoted keys | { name: "Alice" } | ✅ | | Trailing commas | { "a": 1, } | ✅ | | Schema mismatches | Wrong types, missing fields | ✅ (retry prompt) |

Agentic Loop Example

async function getStructuredData(prompt: string, schema: z.ZodType) {
  let attempts = 0;
  let currentPrompt = prompt;
  
  while (attempts < 3) {
    const aiOutput = await callLLM(currentPrompt);
    const result = safeParseAI(aiOutput, schema);
    
    if (result.success) {
      return result.data;
    }
    
    // Use the auto-generated retry prompt
    currentPrompt = result.retryPrompt;
    attempts++;
  }
  
  throw new Error('Failed to get valid structured data');
}

License

MIT