**Fault Tolerance**:
- `FaultTolerantClient` wrapper (retry, circuit breaker)
- Graceful degradation (e.g., robots.txt parsing continues on errors)

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## Key Components

### Crawler (`Crawler.java`)

Main orchestrator for crawling operations.

**Key Methods**:
```java
String execute()                // Start crawling, return session ID
void addUrl(String url)         // Add URL to queue