Anthropic Reliability Patterns

Overview

Build fault-tolerant Claude integrations with built-in SDK retries, model fallback chains (Sonnet → Haiku), circuit breakers to avoid hammering a failing API, graceful degradation with cached/static responses, and per-request timeout configuration.

Built-In SDK Retries

The SDK retries 429 (rate limit) and 529 (overloaded) automatically:

const client = new Anthropic({
  maxRetries: 3, // default: 2
  timeout: 120_000, // 2 minutes
});

Model Fallback Chain

const FALLBACK_CHAIN = ['claude-sonnet-4-20250514', 'claude-haiku-4-5-20251001'];

async function callWithFallback(params: Anthropic.MessageCreateParams) {
  for (const model of FALLBACK_CHAIN) {
    try {
      return await client.messages.create({ ...params, model });
    } catch (err) {
      if (err instanceof Anthropic.APIError && err.status >= 500) {
        console.warn(`${model} failed (${err.status}), trying next...`);
        continue;
      }
      throw err; // Don't retry client errors (4xx)
    }
  }
  throw new Error('All models failed');
}

Circuit Breaker

class ClaudeCircuitBreaker {
  private failures = 0;
  private lastFailure = 0;
  private readonly threshold = 5;
  private readonly resetMs = 60_000;

  async call(params: Anthropic.MessageCreateParams) {
    if (this.failures >= this.threshold && Date.now() - this.lastFailure < this.resetMs) {
      throw new Error('Circuit open — Claude API unavailable');
    }

    try {
      const result = await client.messages.create(params);
      this.failures = 0;
      return result;
    } catch (err) {
      if (err instanceof Anthropic.APIError && err.status >= 500) {
        this.failures++;
        this.lastFailure = Date.now();
      }
      throw err;
    }
  }
}

Graceful Degradation

async function getResponse(userInput: string): Promise<string> {
  try {
    const message = await client.messages.create({
      model: 'claude-sonnet-4-20250514',
      max_tokens: 1024,
      messages: [{ role: 'user', content: userInput }],
    });
    return message.content[0].text;
  } catch (err) {
    // Return cached/static response instead of failing
    console.error('Claude unavailable, using fallback');
    return "I'm temporarily unable to process your request. Please try again shortly.";
  }
}

Timeout Handling

const client = new Anthropic({
  timeout: 30_000, // 30s for most requests
});

// Override per-request for long-running tasks
const message = await client.messages.create(params, {
  timeout: 120_000, // 2 minutes for complex prompts
});

Output

• SDK configured with appropriate maxRetries and timeout
• Model fallback chain automatically trying cheaper models on failure
• Circuit breaker preventing cascading failures during outages
• Graceful degradation returning static responses when Claude is unavailable

Error Handling

Error	Cause	Solution
API Error	Check error type and status code	See clade-common-errors

Examples

See Built-In SDK Retries, Model Fallback Chain, Circuit Breaker class, Graceful Degradation handler, and Timeout Handling above.

Resources

• Error Types
• SDK Retries

Next Steps

See clade-policy-guardrails for content safety patterns.

Prerequisites

• Completed clade-install-auth
• Production Claude integration requiring high availability
• Understanding of fault tolerance patterns (retries, circuit breakers)

Instructions

Step 1: Review the patterns below

Each section contains production-ready code examples. Copy and adapt them to your use case.

Step 2: Apply to your codebase

Integrate the patterns that match your requirements. Test each change individually.

Step 3: Verify

Run your test suite to confirm the integration works correctly.