claude-agent-sdk

# Claude Agent SDK - Structured Outputs & Error Prevention Guide

**Package**: @anthropic-ai/claude-agent-sdk@0.2.12
**Breaking Changes**: v0.1.45 - Structured outputs (Nov 2025), v0.1.0 - No default system prompt, settingSources required

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## What's New in v0.1.45+ (Nov 2025)

**Major Features:**

### 1. Structured Outputs (v0.1.45, Nov 14, 2025)
- **JSON schema validation** - Guarantees responses match exact schemas
- **`outputFormat` parameter** - Define output structure with JSON schema or Zod
- **Access validated results** - Via `message.structured_output`
- **Beta header required**: `structured-outputs-2025-11-13`
- **Type safety** - Full TypeScript inference with Zod schemas

**Example:**
```typescript
import { query } from "@anthropic-ai/claude-agent-sdk";
import { z } from "zod";
import { zodToJsonSchema } from "zod-to-json-schema";

const schema = z.object({
  summary: z.string(),
  sentiment: z.enum(['positive', 'neutral', 'negative']),
  confidence: z.number().min(0).max(1)
});

const response = query({
  prompt: "Analyze this code review feedback",
  options: {
    model: "claude-sonnet-4-5",
    outputFormat: {
      type: "json_schema",
      json_schema: {
        name: "AnalysisResult",
        strict: true,
        schema: zodToJsonSchema(schema)
      }
    }
  }
});

for await (const message of response) {
  if (message.type === 'result' && message.structured_output) {
    // Guaranteed to match schema
    const validated = schema.parse(message.structured_output);
    console.log(`Sentiment: ${validated.sentiment}`);
  }
}
```

**Zod Compatibility (v0.1.71+):** SDK supports both Zod v3.24.1+ and Zod v4.0.0+ as peer dependencies. Import remains `import { z } from "zod"` for either version.

### 2. Plugins System (v0.1.27)
- **`plugins` array** - Load local plugin paths
- **Custom plugin support** - Extend agent capabilities

### 3. Hooks System (v0.1.0+)

**All 12 Hook Events:**

| Hook | When Fired | Use Case |
|------|------------|----------