Summary

• Implement complete fault tolerance API to enable test_fault_tolerance.cpp
• Close issue [TEST] Implement fault tolerance API for test_fault_tolerance.cpp (ARC-001 Phase 1) #329 (ARC-001 Phase 1)

Changes

circuit_breaker.h

• Modify execute() to return result<T> instead of throwing exceptions
• Add validate() method to circuit_breaker_config
• Add get_success_rate() method to circuit_breaker_metrics

retry_policy.h

• Implement retry_executor<T> template class with configurable retry logic
• Add retry_metrics struct for tracking retry statistics
• Add factory functions: create_exponential_backoff_config(), create_fixed_delay_config(), create_fibonacci_backoff_config()
• Add validate() method to retry_config
• Support custom should_retry predicate

fault_tolerance_manager.h

• Implement fault_tolerance_manager<T> template class combining circuit breaker and retry
• Add fault_tolerance_config with enable flags and config options
• Add fault_tolerance_metrics for operation tracking
• Implement execute() and execute_with_timeout() methods
• Add is_healthy() method to check circuit breaker state
• Implement global registries:
  • global_circuit_breaker_registry()
  • global_retry_executor_registry()
  • global_fault_tolerance_registry()

test_fault_tolerance.cpp

• Update test assertions to use is_ok()/is_err() instead of bool conversion
• Enable test in CMakeLists.txt

Documentation

• Update KNOWN_ISSUES.md to reflect test enablement

Test plan

• All 27 fault tolerance tests pass
• Full test suite passes (570/571, 1 pre-existing failure unrelated to this PR)
• Build succeeds on macOS

Closes

Closes #329